drivers/md/raid5.c

   1 /*
   2  * raid5.c : Multiple Devices driver for Linux
   3  *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
   4  *         Copyright (C) 1999, 2000 Ingo Molnar
   5  *         Copyright (C) 2002, 2003 H. Peter Anvin
   6  *
   7  * RAID-4/5/6 management functions.
   8  * Thanks to Penguin Computing for making the RAID-6 development possible
   9  * by donating a test server!
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * (for example /usr/src/linux/COPYING); if not, write to the Free
  18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 /*
  22  * BITMAP UNPLUGGING:
  23  *
  24  * The sequencing for updating the bitmap reliably is a little
  25  * subtle (and I got it wrong the first time) so it deserves some
  26  * explanation.
  27  *
  28  * We group bitmap updates into batches.  Each batch has a number.
  29  * We may write out several batches at once, but that isn't very important.
  30  * conf->seq_write is the number of the last batch successfully written.
  31  * conf->seq_flush is the number of the last batch that was closed to
  32  *    new additions.
  33  * When we discover that we will need to write to any block in a stripe
  34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
  35  * the number of the batch it will be in. This is seq_flush+1.
  36  * When we are ready to do a write, if that batch hasn't been written yet,
  37  *   we plug the array and queue the stripe for later.
  38  * When an unplug happens, we increment bm_flush, thus closing the current
  39  *   batch.
  40  * When we notice that bm_flush > bm_write, we write out all pending updates
  41  * to the bitmap, and advance bm_write to where bm_flush was.
  42  * This may occasionally write a bit out twice, but is sure never to
  43  * miss any bits.
  44  */
  45
  46 #include <linux/blkdev.h>
  47 #include <linux/kthread.h>
  48 #include <linux/raid/pq.h>
  49 #include <linux/async_tx.h>
  50 #include <linux/module.h>
  51 #include <linux/async.h>
  52 #include <linux/seq_file.h>
  53 #include <linux/cpu.h>
  54 #include <linux/slab.h>
  55 #include <linux/ratelimit.h>
  56 #include <linux/nodemask.h>
  57 #include <linux/flex_array.h>
  58 #include <linux/sched/signal.h>
  59
  60 #include <trace/events/block.h>
  61
  62 #include "md.h"
  63 #include "raid5.h"
  64 #include "raid0.h"
  65 #include "bitmap.h"
  66
  67 #define UNSUPPORTED_MDDEV_FLAGS (1L << MD_FAILFAST_SUPPORTED)
  68
  69 #define cpu_to_group(cpu) cpu_to_node(cpu)
  70 #define ANY_GROUP NUMA_NO_NODE
  71
  72 static bool devices_handle_discard_safely = false;
  73 module_param(devices_handle_discard_safely, bool, 0644);
  74 MODULE_PARM_DESC(devices_handle_discard_safely,
  75                  "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
  76 static struct workqueue_struct *raid5_wq;
  77
  78 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
  79 {
  80         int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
  81         return &conf->stripe_hashtbl[hash];
  82 }
  83
  84 static inline int stripe_hash_locks_hash(sector_t sect)
  85 {
  86         return (sect >> STRIPE_SHIFT) & STRIPE_HASH_LOCKS_MASK;
  87 }
  88
  89 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
  90 {
  91         spin_lock_irq(conf->hash_locks + hash);
  92         spin_lock(&conf->device_lock);
  93 }
  94
  95 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
  96 {
  97         spin_unlock(&conf->device_lock);
  98         spin_unlock_irq(conf->hash_locks + hash);
  99 }
 100
 101 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
 102 {
 103         int i;
 104         local_irq_disable();
 105         spin_lock(conf->hash_locks);
 106         for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
 107                 spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
 108         spin_lock(&conf->device_lock);
 109 }
 110
 111 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
 112 {
 113         int i;
 114         spin_unlock(&conf->device_lock);
 115         for (i = NR_STRIPE_HASH_LOCKS; i; i--)
 116                 spin_unlock(conf->hash_locks + i - 1);
 117         local_irq_enable();
 118 }
 119
 120 /* Find first data disk in a raid6 stripe */
 121 static inline int raid6_d0(struct stripe_head *sh)
 122 {
 123         if (sh->ddf_layout)
 124                 /* ddf always start from first device */
 125                 return 0;
 126         /* md starts just after Q block */
 127         if (sh->qd_idx == sh->disks - 1)
 128                 return 0;
 129         else
 130                 return sh->qd_idx + 1;
 131 }
 132 static inline int raid6_next_disk(int disk, int raid_disks)
 133 {
 134         disk++;
 135         return (disk < raid_disks) ? disk : 0;
 136 }
 137
 138 /* When walking through the disks in a raid5, starting at raid6_d0,
 139  * We need to map each disk to a 'slot', where the data disks are slot
 140  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
 141  * is raid_disks-1.  This help does that mapping.
 142  */
 143 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
 144                              int *count, int syndrome_disks)
 145 {
 146         int slot = *count;
 147
 148         if (sh->ddf_layout)
 149                 (*count)++;
 150         if (idx == sh->pd_idx)
 151                 return syndrome_disks;
 152         if (idx == sh->qd_idx)
 153                 return syndrome_disks + 1;
 154         if (!sh->ddf_layout)
 155                 (*count)++;
 156         return slot;
 157 }
 158
 159 static void return_io(struct bio_list *return_bi)
 160 {
 161         struct bio *bi;
 162         while ((bi = bio_list_pop(return_bi)) != NULL) {
 163                 bi->bi_iter.bi_size = 0;
 164                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
 165                                          bi, 0);
 166                 bio_endio(bi);
 167         }
 168 }
 169
 170 static void print_raid5_conf (struct r5conf *conf);
 171
 172 static int stripe_operations_active(struct stripe_head *sh)
 173 {
 174         return sh->check_state || sh->reconstruct_state ||
 175                test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
 176                test_bit(STRIPE_COMPUTE_RUN, &sh->state);
 177 }
 178
 179 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
 180 {
 181         struct r5conf *conf = sh->raid_conf;
 182         struct r5worker_group *group;
 183         int thread_cnt;
 184         int i, cpu = sh->cpu;
 185
 186         if (!cpu_online(cpu)) {
 187                 cpu = cpumask_any(cpu_online_mask);
 188                 sh->cpu = cpu;
 189         }
 190
 191         if (list_empty(&sh->lru)) {
 192                 struct r5worker_group *group;
 193                 group = conf->worker_groups + cpu_to_group(cpu);
 194                 list_add_tail(&sh->lru, &group->handle_list);
 195                 group->stripes_cnt++;
 196                 sh->group = group;
 197         }
 198
 199         if (conf->worker_cnt_per_group == 0) {
 200                 md_wakeup_thread(conf->mddev->thread);
 201                 return;
 202         }
 203
 204         group = conf->worker_groups + cpu_to_group(sh->cpu);
 205
 206         group->workers[0].working = true;
 207         /* at least one worker should run to avoid race */
 208         queue_work_on(sh->cpu, raid5_wq, &group->workers[0].work);
 209
 210         thread_cnt = group->stripes_cnt / MAX_STRIPE_BATCH - 1;
 211         /* wakeup more workers */
 212         for (i = 1; i < conf->worker_cnt_per_group && thread_cnt > 0; i++) {
 213                 if (group->workers[i].working == false) {
 214                         group->workers[i].working = true;
 215                         queue_work_on(sh->cpu, raid5_wq,
 216                                       &group->workers[i].work);
 217                         thread_cnt--;
 218                 }
 219         }
 220 }
 221
 222 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
 223                               struct list_head *temp_inactive_list)
 224 {
 225         int i;
 226         int injournal = 0;      /* number of date pages with R5_InJournal */
 227
 228         BUG_ON(!list_empty(&sh->lru));
 229         BUG_ON(atomic_read(&conf->active_stripes)==0);
 230
 231         if (r5c_is_writeback(conf->log))
 232                 for (i = sh->disks; i--; )
 233                         if (test_bit(R5_InJournal, &sh->dev[i].flags))
 234                                 injournal++;
 235         /*
 236          * When quiesce in r5c write back, set STRIPE_HANDLE for stripes with
 237          * data in journal, so they are not released to cached lists
 238          */
 239         if (conf->quiesce && r5c_is_writeback(conf->log) &&
 240             !test_bit(STRIPE_HANDLE, &sh->state) && injournal != 0) {
 241                 if (test_bit(STRIPE_R5C_CACHING, &sh->state))
 242                         r5c_make_stripe_write_out(sh);
 243                 set_bit(STRIPE_HANDLE, &sh->state);
 244         }
 245
 246         if (test_bit(STRIPE_HANDLE, &sh->state)) {
 247                 if (test_bit(STRIPE_DELAYED, &sh->state) &&
 248                     !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 249                         list_add_tail(&sh->lru, &conf->delayed_list);
 250                 else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
 251                            sh->bm_seq - conf->seq_write > 0)
 252                         list_add_tail(&sh->lru, &conf->bitmap_list);
 253                 else {
 254                         clear_bit(STRIPE_DELAYED, &sh->state);
 255                         clear_bit(STRIPE_BIT_DELAY, &sh->state);
 256                         if (conf->worker_cnt_per_group == 0) {
 257                                 list_add_tail(&sh->lru, &conf->handle_list);
 258                         } else {
 259                                 raid5_wakeup_stripe_thread(sh);
 260                                 return;
 261                         }
 262                 }
 263                 md_wakeup_thread(conf->mddev->thread);
 264         } else {
 265                 BUG_ON(stripe_operations_active(sh));
 266                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 267                         if (atomic_dec_return(&conf->preread_active_stripes)
 268                             < IO_THRESHOLD)
 269                                 md_wakeup_thread(conf->mddev->thread);
 270                 atomic_dec(&conf->active_stripes);
 271                 if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
 272                         if (!r5c_is_writeback(conf->log))
 273                                 list_add_tail(&sh->lru, temp_inactive_list);
 274                         else {
 275                                 WARN_ON(test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags));
 276                                 if (injournal == 0)
 277                                         list_add_tail(&sh->lru, temp_inactive_list);
 278                                 else if (injournal == conf->raid_disks - conf->max_degraded) {
 279                                         /* full stripe */
 280                                         if (!test_and_set_bit(STRIPE_R5C_FULL_STRIPE, &sh->state))
 281                                                 atomic_inc(&conf->r5c_cached_full_stripes);
 282                                         if (test_and_clear_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state))
 283                                                 atomic_dec(&conf->r5c_cached_partial_stripes);
 284                                         list_add_tail(&sh->lru, &conf->r5c_full_stripe_list);
 285                                         r5c_check_cached_full_stripe(conf);
 286                                 } else
 287                                         /*
 288                                          * STRIPE_R5C_PARTIAL_STRIPE is set in
 289                                          * r5c_try_caching_write(). No need to
 290                                          * set it again.
 291                                          */
 292                                         list_add_tail(&sh->lru, &conf->r5c_partial_stripe_list);
 293                         }
 294                 }
 295         }
 296 }
 297
 298 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
 299                              struct list_head *temp_inactive_list)
 300 {
 301         if (atomic_dec_and_test(&sh->count))
 302                 do_release_stripe(conf, sh, temp_inactive_list);
 303 }
 304
 305 /*
 306  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
 307  *
 308  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
 309  * given time. Adding stripes only takes device lock, while deleting stripes
 310  * only takes hash lock.
 311  */
 312 static void release_inactive_stripe_list(struct r5conf *conf,
 313                                          struct list_head *temp_inactive_list,
 314                                          int hash)
 315 {
 316         int size;
 317         bool do_wakeup = false;
 318         unsigned long flags;
 319
 320         if (hash == NR_STRIPE_HASH_LOCKS) {
 321                 size = NR_STRIPE_HASH_LOCKS;
 322                 hash = NR_STRIPE_HASH_LOCKS - 1;
 323         } else
 324                 size = 1;
 325         while (size) {
 326                 struct list_head *list = &temp_inactive_list[size - 1];
 327
 328                 /*
 329                  * We don't hold any lock here yet, raid5_get_active_stripe() might
 330                  * remove stripes from the list
 331                  */
 332                 if (!list_empty_careful(list)) {
 333                         spin_lock_irqsave(conf->hash_locks + hash, flags);
 334                         if (list_empty(conf->inactive_list + hash) &&
 335                             !list_empty(list))
 336                                 atomic_dec(&conf->empty_inactive_list_nr);
 337                         list_splice_tail_init(list, conf->inactive_list + hash);
 338                         do_wakeup = true;
 339                         spin_unlock_irqrestore(conf->hash_locks + hash, flags);
 340                 }
 341                 size--;
 342                 hash--;
 343         }
 344
 345         if (do_wakeup) {
 346                 wake_up(&conf->wait_for_stripe);
 347                 if (atomic_read(&conf->active_stripes) == 0)
 348                         wake_up(&conf->wait_for_quiescent);
 349                 if (conf->retry_read_aligned)
 350                         md_wakeup_thread(conf->mddev->thread);
 351         }
 352 }
 353
 354 /* should hold conf->device_lock already */
 355 static int release_stripe_list(struct r5conf *conf,
 356                                struct list_head *temp_inactive_list)
 357 {
 358         struct stripe_head *sh, *t;
 359         int count = 0;
 360         struct llist_node *head;
 361
 362         head = llist_del_all(&conf->released_stripes);
 363         head = llist_reverse_order(head);
 364         llist_for_each_entry_safe(sh, t, head, release_list) {
 365                 int hash;
 366
 367                 /* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
 368                 smp_mb();
 369                 clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
 370                 /*
 371                  * Don't worry the bit is set here, because if the bit is set
 372                  * again, the count is always > 1. This is true for
 373                  * STRIPE_ON_UNPLUG_LIST bit too.
 374                  */
 375                 hash = sh->hash_lock_index;
 376                 __release_stripe(conf, sh, &temp_inactive_list[hash]);
 377                 count++;
 378         }
 379
 380         return count;
 381 }
 382
 383 void raid5_release_stripe(struct stripe_head *sh)
 384 {
 385         struct r5conf *conf = sh->raid_conf;
 386         unsigned long flags;
 387         struct list_head list;
 388         int hash;
 389         bool wakeup;
 390
 391         /* Avoid release_list until the last reference.
 392          */
 393         if (atomic_add_unless(&sh->count, -1, 1))
 394                 return;
 395
 396         if (unlikely(!conf->mddev->thread) ||
 397                 test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
 398                 goto slow_path;
 399         wakeup = llist_add(&sh->release_list, &conf->released_stripes);
 400         if (wakeup)
 401                 md_wakeup_thread(conf->mddev->thread);
 402         return;
 403 slow_path:
 404         local_irq_save(flags);
 405         /* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
 406         if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
 407                 INIT_LIST_HEAD(&list);
 408                 hash = sh->hash_lock_index;
 409                 do_release_stripe(conf, sh, &list);
 410                 spin_unlock(&conf->device_lock);
 411                 release_inactive_stripe_list(conf, &list, hash);
 412         }
 413         local_irq_restore(flags);
 414 }
 415
 416 static inline void remove_hash(struct stripe_head *sh)
 417 {
 418         pr_debug("remove_hash(), stripe %llu\n",
 419                 (unsigned long long)sh->sector);
 420
 421         hlist_del_init(&sh->hash);
 422 }
 423
 424 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
 425 {
 426         struct hlist_head *hp = stripe_hash(conf, sh->sector);
 427
 428         pr_debug("insert_hash(), stripe %llu\n",
 429                 (unsigned long long)sh->sector);
 430
 431         hlist_add_head(&sh->hash, hp);
 432 }
 433
 434 /* find an idle stripe, make sure it is unhashed, and return it. */
 435 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
 436 {
 437         struct stripe_head *sh = NULL;
 438         struct list_head *first;
 439
 440         if (list_empty(conf->inactive_list + hash))
 441                 goto out;
 442         first = (conf->inactive_list + hash)->next;
 443         sh = list_entry(first, struct stripe_head, lru);
 444         list_del_init(first);
 445         remove_hash(sh);
 446         atomic_inc(&conf->active_stripes);
 447         BUG_ON(hash != sh->hash_lock_index);
 448         if (list_empty(conf->inactive_list + hash))
 449                 atomic_inc(&conf->empty_inactive_list_nr);
 450 out:
 451         return sh;
 452 }
 453
 454 static void shrink_buffers(struct stripe_head *sh)
 455 {
 456         struct page *p;
 457         int i;
 458         int num = sh->raid_conf->pool_size;
 459
 460         for (i = 0; i < num ; i++) {
 461                 WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
 462                 p = sh->dev[i].page;
 463                 if (!p)
 464                         continue;
 465                 sh->dev[i].page = NULL;
 466                 put_page(p);
 467         }
 468 }
 469
 470 static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
 471 {
 472         int i;
 473         int num = sh->raid_conf->pool_size;
 474
 475         for (i = 0; i < num; i++) {
 476                 struct page *page;
 477
 478                 if (!(page = alloc_page(gfp))) {
 479                         return 1;
 480                 }
 481                 sh->dev[i].page = page;
 482                 sh->dev[i].orig_page = page;
 483         }
 484         return 0;
 485 }
 486
 487 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
 488 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
 489                             struct stripe_head *sh);
 490
 491 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 492 {
 493         struct r5conf *conf = sh->raid_conf;
 494         int i, seq;
 495
 496         BUG_ON(atomic_read(&sh->count) != 0);
 497         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
 498         BUG_ON(stripe_operations_active(sh));
 499         BUG_ON(sh->batch_head);
 500
 501         pr_debug("init_stripe called, stripe %llu\n",
 502                 (unsigned long long)sector);
 503 retry:
 504         seq = read_seqcount_begin(&conf->gen_lock);
 505         sh->generation = conf->generation - previous;
 506         sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 507         sh->sector = sector;
 508         stripe_set_idx(sector, conf, previous, sh);
 509         sh->state = 0;
 510
 511         for (i = sh->disks; i--; ) {
 512                 struct r5dev *dev = &sh->dev[i];
 513
 514                 if (dev->toread || dev->read || dev->towrite || dev->written ||
 515                     test_bit(R5_LOCKED, &dev->flags)) {
 516                         pr_err("sector=%llx i=%d %p %p %p %p %d\n",
 517                                (unsigned long long)sh->sector, i, dev->toread,
 518                                dev->read, dev->towrite, dev->written,
 519                                test_bit(R5_LOCKED, &dev->flags));
 520                         WARN_ON(1);
 521                 }
 522                 dev->flags = 0;
 523                 raid5_build_block(sh, i, previous);
 524         }
 525         if (read_seqcount_retry(&conf->gen_lock, seq))
 526                 goto retry;
 527         sh->overwrite_disks = 0;
 528         insert_hash(conf, sh);
 529         sh->cpu = smp_processor_id();
 530         set_bit(STRIPE_BATCH_READY, &sh->state);
 531 }
 532
 533 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
 534                                          short generation)
 535 {
 536         struct stripe_head *sh;
 537
 538         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 539         hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
 540                 if (sh->sector == sector && sh->generation == generation)
 541                         return sh;
 542         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 543         return NULL;
 544 }
 545
 546 /*
 547  * Need to check if array has failed when deciding whether to:
 548  *  - start an array
 549  *  - remove non-faulty devices
 550  *  - add a spare
 551  *  - allow a reshape
 552  * This determination is simple when no reshape is happening.
 553  * However if there is a reshape, we need to carefully check
 554  * both the before and after sections.
 555  * This is because some failed devices may only affect one
 556  * of the two sections, and some non-in_sync devices may
 557  * be insync in the section most affected by failed devices.
 558  */
 559 int raid5_calc_degraded(struct r5conf *conf)
 560 {
 561         int degraded, degraded2;
 562         int i;
 563
 564         rcu_read_lock();
 565         degraded = 0;
 566         for (i = 0; i < conf->previous_raid_disks; i++) {
 567                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 568                 if (rdev && test_bit(Faulty, &rdev->flags))
 569                         rdev = rcu_dereference(conf->disks[i].replacement);
 570                 if (!rdev || test_bit(Faulty, &rdev->flags))
 571                         degraded++;
 572                 else if (test_bit(In_sync, &rdev->flags))
 573                         ;
 574                 else
 575                         /* not in-sync or faulty.
 576                          * If the reshape increases the number of devices,
 577                          * this is being recovered by the reshape, so
 578                          * this 'previous' section is not in_sync.
 579                          * If the number of devices is being reduced however,
 580                          * the device can only be part of the array if
 581                          * we are reverting a reshape, so this section will
 582                          * be in-sync.
 583                          */
 584                         if (conf->raid_disks >= conf->previous_raid_disks)
 585                                 degraded++;
 586         }
 587         rcu_read_unlock();
 588         if (conf->raid_disks == conf->previous_raid_disks)
 589                 return degraded;
 590         rcu_read_lock();
 591         degraded2 = 0;
 592         for (i = 0; i < conf->raid_disks; i++) {
 593                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 594                 if (rdev && test_bit(Faulty, &rdev->flags))
 595                         rdev = rcu_dereference(conf->disks[i].replacement);
 596                 if (!rdev || test_bit(Faulty, &rdev->flags))
 597                         degraded2++;
 598                 else if (test_bit(In_sync, &rdev->flags))
 599                         ;
 600                 else
 601                         /* not in-sync or faulty.
 602                          * If reshape increases the number of devices, this
 603                          * section has already been recovered, else it
 604                          * almost certainly hasn't.
 605                          */
 606                         if (conf->raid_disks <= conf->previous_raid_disks)
 607                                 degraded2++;
 608         }
 609         rcu_read_unlock();
 610         if (degraded2 > degraded)
 611                 return degraded2;
 612         return degraded;
 613 }
 614
 615 static int has_failed(struct r5conf *conf)
 616 {
 617         int degraded;
 618
 619         if (conf->mddev->reshape_position == MaxSector)
 620                 return conf->mddev->degraded > conf->max_degraded;
 621
 622         degraded = raid5_calc_degraded(conf);
 623         if (degraded > conf->max_degraded)
 624                 return 1;
 625         return 0;
 626 }
 627
 628 struct stripe_head *
 629 raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
 630                         int previous, int noblock, int noquiesce)
 631 {
 632         struct stripe_head *sh;
 633         int hash = stripe_hash_locks_hash(sector);
 634         int inc_empty_inactive_list_flag;
 635
 636         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 637
 638         spin_lock_irq(conf->hash_locks + hash);
 639
 640         do {
 641                 wait_event_lock_irq(conf->wait_for_quiescent,
 642                                     conf->quiesce == 0 || noquiesce,
 643                                     *(conf->hash_locks + hash));
 644                 sh = __find_stripe(conf, sector, conf->generation - previous);
 645                 if (!sh) {
 646                         if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
 647                                 sh = get_free_stripe(conf, hash);
 648                                 if (!sh && !test_bit(R5_DID_ALLOC,
 649                                                      &conf->cache_state))
 650                                         set_bit(R5_ALLOC_MORE,
 651                                                 &conf->cache_state);
 652                         }
 653                         if (noblock && sh == NULL)
 654                                 break;
 655
 656                         r5c_check_stripe_cache_usage(conf);
 657                         if (!sh) {
 658                                 set_bit(R5_INACTIVE_BLOCKED,
 659                                         &conf->cache_state);
 660                                 r5l_wake_reclaim(conf->log, 0);
 661                                 wait_event_lock_irq(
 662                                         conf->wait_for_stripe,
 663                                         !list_empty(conf->inactive_list + hash) &&
 664                                         (atomic_read(&conf->active_stripes)
 665                                          < (conf->max_nr_stripes * 3 / 4)
 666                                          || !test_bit(R5_INACTIVE_BLOCKED,
 667                                                       &conf->cache_state)),
 668                                         *(conf->hash_locks + hash));
 669                                 clear_bit(R5_INACTIVE_BLOCKED,
 670                                           &conf->cache_state);
 671                         } else {
 672                                 init_stripe(sh, sector, previous);
 673                                 atomic_inc(&sh->count);
 674                         }
 675                 } else if (!atomic_inc_not_zero(&sh->count)) {
 676                         spin_lock(&conf->device_lock);
 677                         if (!atomic_read(&sh->count)) {
 678                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 679                                         atomic_inc(&conf->active_stripes);
 680                                 BUG_ON(list_empty(&sh->lru) &&
 681                                        !test_bit(STRIPE_EXPANDING, &sh->state));
 682                                 inc_empty_inactive_list_flag = 0;
 683                                 if (!list_empty(conf->inactive_list + hash))
 684                                         inc_empty_inactive_list_flag = 1;
 685                                 list_del_init(&sh->lru);
 686                                 if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
 687                                         atomic_inc(&conf->empty_inactive_list_nr);
 688                                 if (sh->group) {
 689                                         sh->group->stripes_cnt--;
 690                                         sh->group = NULL;
 691                                 }
 692                         }
 693                         atomic_inc(&sh->count);
 694                         spin_unlock(&conf->device_lock);
 695                 }
 696         } while (sh == NULL);
 697
 698         spin_unlock_irq(conf->hash_locks + hash);
 699         return sh;
 700 }
 701
 702 static bool is_full_stripe_write(struct stripe_head *sh)
 703 {
 704         BUG_ON(sh->overwrite_disks > (sh->disks - sh->raid_conf->max_degraded));
 705         return sh->overwrite_disks == (sh->disks - sh->raid_conf->max_degraded);
 706 }
 707
 708 static void lock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
 709 {
 710         local_irq_disable();
 711         if (sh1 > sh2) {
 712                 spin_lock(&sh2->stripe_lock);
 713                 spin_lock_nested(&sh1->stripe_lock, 1);
 714         } else {
 715                 spin_lock(&sh1->stripe_lock);
 716                 spin_lock_nested(&sh2->stripe_lock, 1);
 717         }
 718 }
 719
 720 static void unlock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
 721 {
 722         spin_unlock(&sh1->stripe_lock);
 723         spin_unlock(&sh2->stripe_lock);
 724         local_irq_enable();
 725 }
 726
 727 /* Only freshly new full stripe normal write stripe can be added to a batch list */
 728 static bool stripe_can_batch(struct stripe_head *sh)
 729 {
 730         struct r5conf *conf = sh->raid_conf;
 731
 732         if (conf->log)
 733                 return false;
 734         return test_bit(STRIPE_BATCH_READY, &sh->state) &&
 735                 !test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
 736                 is_full_stripe_write(sh);
 737 }
 738
 739 /* we only do back search */
 740 static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh)
 741 {
 742         struct stripe_head *head;
 743         sector_t head_sector, tmp_sec;
 744         int hash;
 745         int dd_idx;
 746         int inc_empty_inactive_list_flag;
 747
 748         /* Don't cross chunks, so stripe pd_idx/qd_idx is the same */
 749         tmp_sec = sh->sector;
 750         if (!sector_div(tmp_sec, conf->chunk_sectors))
 751                 return;
 752         head_sector = sh->sector - STRIPE_SECTORS;
 753
 754         hash = stripe_hash_locks_hash(head_sector);
 755         spin_lock_irq(conf->hash_locks + hash);
 756         head = __find_stripe(conf, head_sector, conf->generation);
 757         if (head && !atomic_inc_not_zero(&head->count)) {
 758                 spin_lock(&conf->device_lock);
 759                 if (!atomic_read(&head->count)) {
 760                         if (!test_bit(STRIPE_HANDLE, &head->state))
 761                                 atomic_inc(&conf->active_stripes);
 762                         BUG_ON(list_empty(&head->lru) &&
 763                                !test_bit(STRIPE_EXPANDING, &head->state));
 764                         inc_empty_inactive_list_flag = 0;
 765                         if (!list_empty(conf->inactive_list + hash))
 766                                 inc_empty_inactive_list_flag = 1;
 767                         list_del_init(&head->lru);
 768                         if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
 769                                 atomic_inc(&conf->empty_inactive_list_nr);
 770                         if (head->group) {
 771                                 head->group->stripes_cnt--;
 772                                 head->group = NULL;
 773                         }
 774                 }
 775                 atomic_inc(&head->count);
 776                 spin_unlock(&conf->device_lock);
 777         }
 778         spin_unlock_irq(conf->hash_locks + hash);
 779
 780         if (!head)
 781                 return;
 782         if (!stripe_can_batch(head))
 783                 goto out;
 784
 785         lock_two_stripes(head, sh);
 786         /* clear_batch_ready clear the flag */
 787         if (!stripe_can_batch(head) || !stripe_can_batch(sh))
 788                 goto unlock_out;
 789
 790         if (sh->batch_head)
 791                 goto unlock_out;
 792
 793         dd_idx = 0;
 794         while (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
 795                 dd_idx++;
 796         if (head->dev[dd_idx].towrite->bi_opf != sh->dev[dd_idx].towrite->bi_opf ||
 797             bio_op(head->dev[dd_idx].towrite) != bio_op(sh->dev[dd_idx].towrite))
 798                 goto unlock_out;
 799
 800         if (head->batch_head) {
 801                 spin_lock(&head->batch_head->batch_lock);
 802                 /* This batch list is already running */
 803                 if (!stripe_can_batch(head)) {
 804                         spin_unlock(&head->batch_head->batch_lock);
 805                         goto unlock_out;
 806                 }
 807
 808                 /*
 809                  * at this point, head's BATCH_READY could be cleared, but we
 810                  * can still add the stripe to batch list
 811                  */
 812                 list_add(&sh->batch_list, &head->batch_list);
 813                 spin_unlock(&head->batch_head->batch_lock);
 814
 815                 sh->batch_head = head->batch_head;
 816         } else {
 817                 head->batch_head = head;
 818                 sh->batch_head = head->batch_head;
 819                 spin_lock(&head->batch_lock);
 820                 list_add_tail(&sh->batch_list, &head->batch_list);
 821                 spin_unlock(&head->batch_lock);
 822         }
 823
 824         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 825                 if (atomic_dec_return(&conf->preread_active_stripes)
 826                     < IO_THRESHOLD)
 827                         md_wakeup_thread(conf->mddev->thread);
 828
 829         if (test_and_clear_bit(STRIPE_BIT_DELAY, &sh->state)) {
 830                 int seq = sh->bm_seq;
 831                 if (test_bit(STRIPE_BIT_DELAY, &sh->batch_head->state) &&
 832                     sh->batch_head->bm_seq > seq)
 833                         seq = sh->batch_head->bm_seq;
 834                 set_bit(STRIPE_BIT_DELAY, &sh->batch_head->state);
 835                 sh->batch_head->bm_seq = seq;
 836         }
 837
 838         atomic_inc(&sh->count);
 839 unlock_out:
 840         unlock_two_stripes(head, sh);
 841 out:
 842         raid5_release_stripe(head);
 843 }
 844
 845 /* Determine if 'data_offset' or 'new_data_offset' should be used
 846  * in this stripe_head.
 847  */
 848 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
 849 {
 850         sector_t progress = conf->reshape_progress;
 851         /* Need a memory barrier to make sure we see the value
 852          * of conf->generation, or ->data_offset that was set before
 853          * reshape_progress was updated.
 854          */
 855         smp_rmb();
 856         if (progress == MaxSector)
 857                 return 0;
 858         if (sh->generation == conf->generation - 1)
 859                 return 0;
 860         /* We are in a reshape, and this is a new-generation stripe,
 861          * so use new_data_offset.
 862          */
 863         return 1;
 864 }
 865
 866 static void flush_deferred_bios(struct r5conf *conf)
 867 {
 868         struct bio_list tmp;
 869         struct bio *bio;
 870
 871         if (!conf->batch_bio_dispatch || !conf->group_cnt)
 872                 return;
 873
 874         bio_list_init(&tmp);
 875         spin_lock(&conf->pending_bios_lock);
 876         bio_list_merge(&tmp, &conf->pending_bios);
 877         bio_list_init(&conf->pending_bios);
 878         spin_unlock(&conf->pending_bios_lock);
 879
 880         while ((bio = bio_list_pop(&tmp)))
 881                 generic_make_request(bio);
 882 }
 883
 884 static void defer_bio_issue(struct r5conf *conf, struct bio *bio)
 885 {
 886         /*
 887          * change group_cnt will drain all bios, so this is safe
 888          *
 889          * A read generally means a read-modify-write, which usually means a
 890          * randwrite, so we don't delay it
 891          */
 892         if (!conf->batch_bio_dispatch || !conf->group_cnt ||
 893             bio_op(bio) == REQ_OP_READ) {
 894                 generic_make_request(bio);
 895                 return;
 896         }
 897         spin_lock(&conf->pending_bios_lock);
 898         bio_list_add(&conf->pending_bios, bio);
 899         spin_unlock(&conf->pending_bios_lock);
 900         md_wakeup_thread(conf->mddev->thread);
 901 }
 902
 903 static void
 904 raid5_end_read_request(struct bio *bi);
 905 static void
 906 raid5_end_write_request(struct bio *bi);
 907
 908 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 909 {
 910         struct r5conf *conf = sh->raid_conf;
 911         int i, disks = sh->disks;
 912         struct stripe_head *head_sh = sh;
 913
 914         might_sleep();
 915
 916         if (!test_bit(STRIPE_R5C_CACHING, &sh->state)) {
 917                 /* writing out phase */
 918                 if (s->waiting_extra_page)
 919                         return;
 920                 if (r5l_write_stripe(conf->log, sh) == 0)
 921                         return;
 922         } else {  /* caching phase */
 923                 if (test_bit(STRIPE_LOG_TRAPPED, &sh->state)) {
 924                         r5c_cache_data(conf->log, sh, s);
 925                         return;
 926                 }
 927         }
 928
 929         for (i = disks; i--; ) {
 930                 int op, op_flags = 0;
 931                 int replace_only = 0;
 932                 struct bio *bi, *rbi;
 933                 struct md_rdev *rdev, *rrdev = NULL;
 934
 935                 sh = head_sh;
 936                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
 937                         op = REQ_OP_WRITE;
 938                         if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
 939                                 op_flags = REQ_FUA;
 940                         if (test_bit(R5_Discard, &sh->dev[i].flags))
 941                                 op = REQ_OP_DISCARD;
 942                 } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
 943                         op = REQ_OP_READ;
 944                 else if (test_and_clear_bit(R5_WantReplace,
 945                                             &sh->dev[i].flags)) {
 946                         op = REQ_OP_WRITE;
 947                         replace_only = 1;
 948                 } else
 949                         continue;
 950                 if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
 951                         op_flags |= REQ_SYNC;
 952
 953 again:
 954                 bi = &sh->dev[i].req;
 955                 rbi = &sh->dev[i].rreq; /* For writing to replacement */
 956
 957                 rcu_read_lock();
 958                 rrdev = rcu_dereference(conf->disks[i].replacement);
 959                 smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
 960                 rdev = rcu_dereference(conf->disks[i].rdev);
 961                 if (!rdev) {
 962                         rdev = rrdev;
 963                         rrdev = NULL;
 964                 }
 965                 if (op_is_write(op)) {
 966                         if (replace_only)
 967                                 rdev = NULL;
 968                         if (rdev == rrdev)
 969                                 /* We raced and saw duplicates */
 970                                 rrdev = NULL;
 971                 } else {
 972                         if (test_bit(R5_ReadRepl, &head_sh->dev[i].flags) && rrdev)
 973                                 rdev = rrdev;
 974                         rrdev = NULL;
 975                 }
 976
 977                 if (rdev && test_bit(Faulty, &rdev->flags))
 978                         rdev = NULL;
 979                 if (rdev)
 980                         atomic_inc(&rdev->nr_pending);
 981                 if (rrdev && test_bit(Faulty, &rrdev->flags))
 982                         rrdev = NULL;
 983                 if (rrdev)
 984                         atomic_inc(&rrdev->nr_pending);
 985                 rcu_read_unlock();
 986
 987                 /* We have already checked bad blocks for reads.  Now
 988                  * need to check for writes.  We never accept write errors
 989                  * on the replacement, so we don't to check rrdev.
 990                  */
 991                 while (op_is_write(op) && rdev &&
 992                        test_bit(WriteErrorSeen, &rdev->flags)) {
 993                         sector_t first_bad;
 994                         int bad_sectors;
 995                         int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
 996                                               &first_bad, &bad_sectors);
 997                         if (!bad)
 998                                 break;
 999
1000                         if (bad < 0) {
1001                                 set_bit(BlockedBadBlocks, &rdev->flags);
1002                                 if (!conf->mddev->external &&
1003                                     conf->mddev->sb_flags) {
1004                                         /* It is very unlikely, but we might
1005                                          * still need to write out the
1006                                          * bad block log - better give it
1007                                          * a chance*/
1008                                         md_check_recovery(conf->mddev);
1009                                 }
1010                                 /*
1011                                  * Because md_wait_for_blocked_rdev
1012                                  * will dec nr_pending, we must
1013                                  * increment it first.
1014                                  */
1015                                 atomic_inc(&rdev->nr_pending);
1016                                 md_wait_for_blocked_rdev(rdev, conf->mddev);
1017                         } else {
1018                                 /* Acknowledged bad block - skip the write */
1019                                 rdev_dec_pending(rdev, conf->mddev);
1020                                 rdev = NULL;
1021                         }
1022                 }
1023
1024                 if (rdev) {
1025                         if (s->syncing || s->expanding || s->expanded
1026                             || s->replacing)
1027                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
1028
1029                         set_bit(STRIPE_IO_STARTED, &sh->state);
1030
1031                         bi->bi_bdev = rdev->bdev;
1032                         bio_set_op_attrs(bi, op, op_flags);
1033                         bi->bi_end_io = op_is_write(op)
1034                                 ? raid5_end_write_request
1035                                 : raid5_end_read_request;
1036                         bi->bi_private = sh;
1037
1038                         pr_debug("%s: for %llu schedule op %d on disc %d\n",
1039                                 __func__, (unsigned long long)sh->sector,
1040                                 bi->bi_opf, i);
1041                         atomic_inc(&sh->count);
1042                         if (sh != head_sh)
1043                                 atomic_inc(&head_sh->count);
1044                         if (use_new_offset(conf, sh))
1045                                 bi->bi_iter.bi_sector = (sh->sector
1046                                                  + rdev->new_data_offset);
1047                         else
1048                                 bi->bi_iter.bi_sector = (sh->sector
1049                                                  + rdev->data_offset);
1050                         if (test_bit(R5_ReadNoMerge, &head_sh->dev[i].flags))
1051                                 bi->bi_opf |= REQ_NOMERGE;
1052
1053                         if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1054                                 WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1055
1056                         if (!op_is_write(op) &&
1057                             test_bit(R5_InJournal, &sh->dev[i].flags))
1058                                 /*
1059                                  * issuing read for a page in journal, this
1060                                  * must be preparing for prexor in rmw; read
1061                                  * the data into orig_page
1062                                  */
1063                                 sh->dev[i].vec.bv_page = sh->dev[i].orig_page;
1064                         else
1065                                 sh->dev[i].vec.bv_page = sh->dev[i].page;
1066                         bi->bi_vcnt = 1;
1067                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1068                         bi->bi_io_vec[0].bv_offset = 0;
1069                         bi->bi_iter.bi_size = STRIPE_SIZE;
1070                         /*
1071                          * If this is discard request, set bi_vcnt 0. We don't
1072                          * want to confuse SCSI because SCSI will replace payload
1073                          */
1074                         if (op == REQ_OP_DISCARD)
1075                                 bi->bi_vcnt = 0;
1076                         if (rrdev)
1077                                 set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
1078
1079                         if (conf->mddev->gendisk)
1080                                 trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
1081                                                       bi, disk_devt(conf->mddev->gendisk),
1082                                                       sh->dev[i].sector);
1083                         defer_bio_issue(conf, bi);
1084                 }
1085                 if (rrdev) {
1086                         if (s->syncing || s->expanding || s->expanded
1087                             || s->replacing)
1088                                 md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
1089
1090                         set_bit(STRIPE_IO_STARTED, &sh->state);
1091
1092                         rbi->bi_bdev = rrdev->bdev;
1093                         bio_set_op_attrs(rbi, op, op_flags);
1094                         BUG_ON(!op_is_write(op));
1095                         rbi->bi_end_io = raid5_end_write_request;
1096                         rbi->bi_private = sh;
1097
1098                         pr_debug("%s: for %llu schedule op %d on "
1099                                  "replacement disc %d\n",
1100                                 __func__, (unsigned long long)sh->sector,
1101                                 rbi->bi_opf, i);
1102                         atomic_inc(&sh->count);
1103                         if (sh != head_sh)
1104                                 atomic_inc(&head_sh->count);
1105                         if (use_new_offset(conf, sh))
1106                                 rbi->bi_iter.bi_sector = (sh->sector
1107                                                   + rrdev->new_data_offset);
1108                         else
1109                                 rbi->bi_iter.bi_sector = (sh->sector
1110                                                   + rrdev->data_offset);
1111                         if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1112                                 WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1113                         sh->dev[i].rvec.bv_page = sh->dev[i].page;
1114                         rbi->bi_vcnt = 1;
1115                         rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1116                         rbi->bi_io_vec[0].bv_offset = 0;
1117                         rbi->bi_iter.bi_size = STRIPE_SIZE;
1118                         /*
1119                          * If this is discard request, set bi_vcnt 0. We don't
1120                          * want to confuse SCSI because SCSI will replace payload
1121                          */
1122                         if (op == REQ_OP_DISCARD)
1123                                 rbi->bi_vcnt = 0;
1124                         if (conf->mddev->gendisk)
1125                                 trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
1126                                                       rbi, disk_devt(conf->mddev->gendisk),
1127                                                       sh->dev[i].sector);
1128                         defer_bio_issue(conf, rbi);
1129                 }
1130                 if (!rdev && !rrdev) {
1131                         if (op_is_write(op))
1132                                 set_bit(STRIPE_DEGRADED, &sh->state);
1133                         pr_debug("skip op %d on disc %d for sector %llu\n",
1134                                 bi->bi_opf, i, (unsigned long long)sh->sector);
1135                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1136                         set_bit(STRIPE_HANDLE, &sh->state);
1137                 }
1138
1139                 if (!head_sh->batch_head)
1140                         continue;
1141                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1142                                       batch_list);
1143                 if (sh != head_sh)
1144                         goto again;
1145         }
1146 }
1147
1148 static struct dma_async_tx_descriptor *
1149 async_copy_data(int frombio, struct bio *bio, struct page **page,
1150         sector_t sector, struct dma_async_tx_descriptor *tx,
1151         struct stripe_head *sh, int no_skipcopy)
1152 {
1153         struct bio_vec bvl;
1154         struct bvec_iter iter;
1155         struct page *bio_page;
1156         int page_offset;
1157         struct async_submit_ctl submit;
1158         enum async_tx_flags flags = 0;
1159
1160         if (bio->bi_iter.bi_sector >= sector)
1161                 page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
1162         else
1163                 page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
1164
1165         if (frombio)
1166                 flags |= ASYNC_TX_FENCE;
1167         init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
1168
1169         bio_for_each_segment(bvl, bio, iter) {
1170                 int len = bvl.bv_len;
1171                 int clen;
1172                 int b_offset = 0;
1173
1174                 if (page_offset < 0) {
1175                         b_offset = -page_offset;
1176                         page_offset += b_offset;
1177                         len -= b_offset;
1178                 }
1179
1180                 if (len > 0 && page_offset + len > STRIPE_SIZE)
1181                         clen = STRIPE_SIZE - page_offset;
1182                 else
1183                         clen = len;
1184
1185                 if (clen > 0) {
1186                         b_offset += bvl.bv_offset;
1187                         bio_page = bvl.bv_page;
1188                         if (frombio) {
1189                                 if (sh->raid_conf->skip_copy &&
1190                                     b_offset == 0 && page_offset == 0 &&
1191                                     clen == STRIPE_SIZE &&
1192                                     !no_skipcopy)
1193                                         *page = bio_page;
1194                                 else
1195                                         tx = async_memcpy(*page, bio_page, page_offset,
1196                                                   b_offset, clen, &submit);
1197                         } else
1198                                 tx = async_memcpy(bio_page, *page, b_offset,
1199                                                   page_offset, clen, &submit);
1200                 }
1201                 /* chain the operations */
1202                 submit.depend_tx = tx;
1203
1204                 if (clen < len) /* hit end of page */
1205                         break;
1206                 page_offset +=  len;
1207         }
1208
1209         return tx;
1210 }
1211
1212 static void ops_complete_biofill(void *stripe_head_ref)
1213 {
1214         struct stripe_head *sh = stripe_head_ref;
1215         struct bio_list return_bi = BIO_EMPTY_LIST;
1216         int i;
1217
1218         pr_debug("%s: stripe %llu\n", __func__,
1219                 (unsigned long long)sh->sector);
1220
1221         /* clear completed biofills */
1222         for (i = sh->disks; i--; ) {
1223                 struct r5dev *dev = &sh->dev[i];
1224
1225                 /* acknowledge completion of a biofill operation */
1226                 /* and check if we need to reply to a read request,
1227                  * new R5_Wantfill requests are held off until
1228                  * !STRIPE_BIOFILL_RUN
1229                  */
1230                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1231                         struct bio *rbi, *rbi2;
1232
1233                         BUG_ON(!dev->read);
1234                         rbi = dev->read;
1235                         dev->read = NULL;
1236                         while (rbi && rbi->bi_iter.bi_sector <
1237                                 dev->sector + STRIPE_SECTORS) {
1238                                 rbi2 = r5_next_bio(rbi, dev->sector);
1239                                 if (!raid5_dec_bi_active_stripes(rbi))
1240                                         bio_list_add(&return_bi, rbi);
1241                                 rbi = rbi2;
1242                         }
1243                 }
1244         }
1245         clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1246
1247         return_io(&return_bi);
1248
1249         set_bit(STRIPE_HANDLE, &sh->state);
1250         raid5_release_stripe(sh);
1251 }
1252
1253 static void ops_run_biofill(struct stripe_head *sh)
1254 {
1255         struct dma_async_tx_descriptor *tx = NULL;
1256         struct async_submit_ctl submit;
1257         int i;
1258
1259         BUG_ON(sh->batch_head);
1260         pr_debug("%s: stripe %llu\n", __func__,
1261                 (unsigned long long)sh->sector);
1262
1263         for (i = sh->disks; i--; ) {
1264                 struct r5dev *dev = &sh->dev[i];
1265                 if (test_bit(R5_Wantfill, &dev->flags)) {
1266                         struct bio *rbi;
1267                         spin_lock_irq(&sh->stripe_lock);
1268                         dev->read = rbi = dev->toread;
1269                         dev->toread = NULL;
1270                         spin_unlock_irq(&sh->stripe_lock);
1271                         while (rbi && rbi->bi_iter.bi_sector <
1272                                 dev->sector + STRIPE_SECTORS) {
1273                                 tx = async_copy_data(0, rbi, &dev->page,
1274                                                      dev->sector, tx, sh, 0);
1275                                 rbi = r5_next_bio(rbi, dev->sector);
1276                         }
1277                 }
1278         }
1279
1280         atomic_inc(&sh->count);
1281         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1282         async_trigger_callback(&submit);
1283 }
1284
1285 static void mark_target_uptodate(struct stripe_head *sh, int target)
1286 {
1287         struct r5dev *tgt;
1288
1289         if (target < 0)
1290                 return;
1291
1292         tgt = &sh->dev[target];
1293         set_bit(R5_UPTODATE, &tgt->flags);
1294         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1295         clear_bit(R5_Wantcompute, &tgt->flags);
1296 }
1297
1298 static void ops_complete_compute(void *stripe_head_ref)
1299 {
1300         struct stripe_head *sh = stripe_head_ref;
1301
1302         pr_debug("%s: stripe %llu\n", __func__,
1303                 (unsigned long long)sh->sector);
1304
1305         /* mark the computed target(s) as uptodate */
1306         mark_target_uptodate(sh, sh->ops.target);
1307         mark_target_uptodate(sh, sh->ops.target2);
1308
1309         clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1310         if (sh->check_state == check_state_compute_run)
1311                 sh->check_state = check_state_compute_result;
1312         set_bit(STRIPE_HANDLE, &sh->state);
1313         raid5_release_stripe(sh);
1314 }
1315
1316 /* return a pointer to the address conversion region of the scribble buffer */
1317 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1318                                  struct raid5_percpu *percpu, int i)
1319 {
1320         void *addr;
1321
1322         addr = flex_array_get(percpu->scribble, i);
1323         return addr + sizeof(struct page *) * (sh->disks + 2);
1324 }
1325
1326 /* return a pointer to the address conversion region of the scribble buffer */
1327 static struct page **to_addr_page(struct raid5_percpu *percpu, int i)
1328 {
1329         void *addr;
1330
1331         addr = flex_array_get(percpu->scribble, i);
1332         return addr;
1333 }
1334
1335 static struct dma_async_tx_descriptor *
1336 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1337 {
1338         int disks = sh->disks;
1339         struct page **xor_srcs = to_addr_page(percpu, 0);
1340         int target = sh->ops.target;
1341         struct r5dev *tgt = &sh->dev[target];
1342         struct page *xor_dest = tgt->page;
1343         int count = 0;
1344         struct dma_async_tx_descriptor *tx;
1345         struct async_submit_ctl submit;
1346         int i;
1347
1348         BUG_ON(sh->batch_head);
1349
1350         pr_debug("%s: stripe %llu block: %d\n",
1351                 __func__, (unsigned long long)sh->sector, target);
1352         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1353
1354         for (i = disks; i--; )
1355                 if (i != target)
1356                         xor_srcs[count++] = sh->dev[i].page;
1357
1358         atomic_inc(&sh->count);
1359
1360         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1361                           ops_complete_compute, sh, to_addr_conv(sh, percpu, 0));
1362         if (unlikely(count == 1))
1363                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1364         else
1365                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1366
1367         return tx;
1368 }
1369
1370 /* set_syndrome_sources - populate source buffers for gen_syndrome
1371  * @srcs - (struct page *) array of size sh->disks
1372  * @sh - stripe_head to parse
1373  *
1374  * Populates srcs in proper layout order for the stripe and returns the
1375  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1376  * destination buffer is recorded in srcs[count] and the Q destination
1377  * is recorded in srcs[count+1]].
1378  */
1379 static int set_syndrome_sources(struct page **srcs,
1380                                 struct stripe_head *sh,
1381                                 int srctype)
1382 {
1383         int disks = sh->disks;
1384         int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1385         int d0_idx = raid6_d0(sh);
1386         int count;
1387         int i;
1388
1389         for (i = 0; i < disks; i++)
1390                 srcs[i] = NULL;
1391
1392         count = 0;
1393         i = d0_idx;
1394         do {
1395                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1396                 struct r5dev *dev = &sh->dev[i];
1397
1398                 if (i == sh->qd_idx || i == sh->pd_idx ||
1399                     (srctype == SYNDROME_SRC_ALL) ||
1400                     (srctype == SYNDROME_SRC_WANT_DRAIN &&
1401                      (test_bit(R5_Wantdrain, &dev->flags) ||
1402                       test_bit(R5_InJournal, &dev->flags))) ||
1403                     (srctype == SYNDROME_SRC_WRITTEN &&
1404                      dev->written)) {
1405                         if (test_bit(R5_InJournal, &dev->flags))
1406                                 srcs[slot] = sh->dev[i].orig_page;
1407                         else
1408                                 srcs[slot] = sh->dev[i].page;
1409                 }
1410                 i = raid6_next_disk(i, disks);
1411         } while (i != d0_idx);
1412
1413         return syndrome_disks;
1414 }
1415
1416 static struct dma_async_tx_descriptor *
1417 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1418 {
1419         int disks = sh->disks;
1420         struct page **blocks = to_addr_page(percpu, 0);
1421         int target;
1422         int qd_idx = sh->qd_idx;
1423         struct dma_async_tx_descriptor *tx;
1424         struct async_submit_ctl submit;
1425         struct r5dev *tgt;
1426         struct page *dest;
1427         int i;
1428         int count;
1429
1430         BUG_ON(sh->batch_head);
1431         if (sh->ops.target < 0)
1432                 target = sh->ops.target2;
1433         else if (sh->ops.target2 < 0)
1434                 target = sh->ops.target;
1435         else
1436                 /* we should only have one valid target */
1437                 BUG();
1438         BUG_ON(target < 0);
1439         pr_debug("%s: stripe %llu block: %d\n",
1440                 __func__, (unsigned long long)sh->sector, target);
1441
1442         tgt = &sh->dev[target];
1443         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1444         dest = tgt->page;
1445
1446         atomic_inc(&sh->count);
1447
1448         if (target == qd_idx) {
1449                 count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1450                 blocks[count] = NULL; /* regenerating p is not necessary */
1451                 BUG_ON(blocks[count+1] != dest); /* q should already be set */
1452                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1453                                   ops_complete_compute, sh,
1454                                   to_addr_conv(sh, percpu, 0));
1455                 tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1456         } else {
1457                 /* Compute any data- or p-drive using XOR */
1458                 count = 0;
1459                 for (i = disks; i-- ; ) {
1460                         if (i == target || i == qd_idx)
1461                                 continue;
1462                         blocks[count++] = sh->dev[i].page;
1463                 }
1464
1465                 init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1466                                   NULL, ops_complete_compute, sh,
1467                                   to_addr_conv(sh, percpu, 0));
1468                 tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1469         }
1470
1471         return tx;
1472 }
1473
1474 static struct dma_async_tx_descriptor *
1475 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1476 {
1477         int i, count, disks = sh->disks;
1478         int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1479         int d0_idx = raid6_d0(sh);
1480         int faila = -1, failb = -1;
1481         int target = sh->ops.target;
1482         int target2 = sh->ops.target2;
1483         struct r5dev *tgt = &sh->dev[target];
1484         struct r5dev *tgt2 = &sh->dev[target2];
1485         struct dma_async_tx_descriptor *tx;
1486         struct page **blocks = to_addr_page(percpu, 0);
1487         struct async_submit_ctl submit;
1488
1489         BUG_ON(sh->batch_head);
1490         pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1491                  __func__, (unsigned long long)sh->sector, target, target2);
1492         BUG_ON(target < 0 || target2 < 0);
1493         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1494         BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1495
1496         /* we need to open-code set_syndrome_sources to handle the
1497          * slot number conversion for 'faila' and 'failb'
1498          */
1499         for (i = 0; i < disks ; i++)
1500                 blocks[i] = NULL;
1501         count = 0;
1502         i = d0_idx;
1503         do {
1504                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1505
1506                 blocks[slot] = sh->dev[i].page;
1507
1508                 if (i == target)
1509                         faila = slot;
1510                 if (i == target2)
1511                         failb = slot;
1512                 i = raid6_next_disk(i, disks);
1513         } while (i != d0_idx);
1514
1515         BUG_ON(faila == failb);
1516         if (failb < faila)
1517                 swap(faila, failb);
1518         pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1519                  __func__, (unsigned long long)sh->sector, faila, failb);
1520
1521         atomic_inc(&sh->count);
1522
1523         if (failb == syndrome_disks+1) {
1524                 /* Q disk is one of the missing disks */
1525                 if (faila == syndrome_disks) {
1526                         /* Missing P+Q, just recompute */
1527                         init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1528                                           ops_complete_compute, sh,
1529                                           to_addr_conv(sh, percpu, 0));
1530                         return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1531                                                   STRIPE_SIZE, &submit);
1532                 } else {
1533                         struct page *dest;
1534                         int data_target;
1535                         int qd_idx = sh->qd_idx;
1536
1537                         /* Missing D+Q: recompute D from P, then recompute Q */
1538                         if (target == qd_idx)
1539                                 data_target = target2;
1540                         else
1541                                 data_target = target;
1542
1543                         count = 0;
1544                         for (i = disks; i-- ; ) {
1545                                 if (i == data_target || i == qd_idx)
1546                                         continue;
1547                                 blocks[count++] = sh->dev[i].page;
1548                         }
1549                         dest = sh->dev[data_target].page;
1550                         init_async_submit(&submit,
1551                                           ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1552                                           NULL, NULL, NULL,
1553                                           to_addr_conv(sh, percpu, 0));
1554                         tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1555                                        &submit);
1556
1557                         count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1558                         init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1559                                           ops_complete_compute, sh,
1560                                           to_addr_conv(sh, percpu, 0));
1561                         return async_gen_syndrome(blocks, 0, count+2,
1562                                                   STRIPE_SIZE, &submit);
1563                 }
1564         } else {
1565                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1566                                   ops_complete_compute, sh,
1567                                   to_addr_conv(sh, percpu, 0));
1568                 if (failb == syndrome_disks) {
1569                         /* We're missing D+P. */
1570                         return async_raid6_datap_recov(syndrome_disks+2,
1571                                                        STRIPE_SIZE, faila,
1572                                                        blocks, &submit);
1573                 } else {
1574                         /* We're missing D+D. */
1575                         return async_raid6_2data_recov(syndrome_disks+2,
1576                                                        STRIPE_SIZE, faila, failb,
1577                                                        blocks, &submit);
1578                 }
1579         }
1580 }
1581
1582 static void ops_complete_prexor(void *stripe_head_ref)
1583 {
1584         struct stripe_head *sh = stripe_head_ref;
1585
1586         pr_debug("%s: stripe %llu\n", __func__,
1587                 (unsigned long long)sh->sector);
1588
1589         if (r5c_is_writeback(sh->raid_conf->log))
1590                 /*
1591                  * raid5-cache write back uses orig_page during prexor.
1592                  * After prexor, it is time to free orig_page
1593                  */
1594                 r5c_release_extra_page(sh);
1595 }
1596
1597 static struct dma_async_tx_descriptor *
1598 ops_run_prexor5(struct stripe_head *sh, struct raid5_percpu *percpu,
1599                 struct dma_async_tx_descriptor *tx)
1600 {
1601         int disks = sh->disks;
1602         struct page **xor_srcs = to_addr_page(percpu, 0);
1603         int count = 0, pd_idx = sh->pd_idx, i;
1604         struct async_submit_ctl submit;
1605
1606         /* existing parity data subtracted */
1607         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1608
1609         BUG_ON(sh->batch_head);
1610         pr_debug("%s: stripe %llu\n", __func__,
1611                 (unsigned long long)sh->sector);
1612
1613         for (i = disks; i--; ) {
1614                 struct r5dev *dev = &sh->dev[i];
1615                 /* Only process blocks that are known to be uptodate */
1616                 if (test_bit(R5_InJournal, &dev->flags))
1617                         xor_srcs[count++] = dev->orig_page;
1618                 else if (test_bit(R5_Wantdrain, &dev->flags))
1619                         xor_srcs[count++] = dev->page;
1620         }
1621
1622         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1623                           ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1624         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1625
1626         return tx;
1627 }
1628
1629 static struct dma_async_tx_descriptor *
1630 ops_run_prexor6(struct stripe_head *sh, struct raid5_percpu *percpu,
1631                 struct dma_async_tx_descriptor *tx)
1632 {
1633         struct page **blocks = to_addr_page(percpu, 0);
1634         int count;
1635         struct async_submit_ctl submit;
1636
1637         pr_debug("%s: stripe %llu\n", __func__,
1638                 (unsigned long long)sh->sector);
1639
1640         count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_WANT_DRAIN);
1641
1642         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_PQ_XOR_DST, tx,
1643                           ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1644         tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1645
1646         return tx;
1647 }
1648
1649 static struct dma_async_tx_descriptor *
1650 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1651 {
1652         struct r5conf *conf = sh->raid_conf;
1653         int disks = sh->disks;
1654         int i;
1655         struct stripe_head *head_sh = sh;
1656
1657         pr_debug("%s: stripe %llu\n", __func__,
1658                 (unsigned long long)sh->sector);
1659
1660         for (i = disks; i--; ) {
1661                 struct r5dev *dev;
1662                 struct bio *chosen;
1663
1664                 sh = head_sh;
1665                 if (test_and_clear_bit(R5_Wantdrain, &head_sh->dev[i].flags)) {
1666                         struct bio *wbi;
1667
1668 again:
1669                         dev = &sh->dev[i];
1670                         /*
1671                          * clear R5_InJournal, so when rewriting a page in
1672                          * journal, it is not skipped by r5l_log_stripe()
1673                          */
1674                         clear_bit(R5_InJournal, &dev->flags);
1675                         spin_lock_irq(&sh->stripe_lock);
1676                         chosen = dev->towrite;
1677                         dev->towrite = NULL;
1678                         sh->overwrite_disks = 0;
1679                         BUG_ON(dev->written);
1680                         wbi = dev->written = chosen;
1681                         spin_unlock_irq(&sh->stripe_lock);
1682                         WARN_ON(dev->page != dev->orig_page);
1683
1684                         while (wbi && wbi->bi_iter.bi_sector <
1685                                 dev->sector + STRIPE_SECTORS) {
1686                                 if (wbi->bi_opf & REQ_FUA)
1687                                         set_bit(R5_WantFUA, &dev->flags);
1688                                 if (wbi->bi_opf & REQ_SYNC)
1689                                         set_bit(R5_SyncIO, &dev->flags);
1690                                 if (bio_op(wbi) == REQ_OP_DISCARD)
1691                                         set_bit(R5_Discard, &dev->flags);
1692                                 else {
1693                                         tx = async_copy_data(1, wbi, &dev->page,
1694                                                              dev->sector, tx, sh,
1695                                                              r5c_is_writeback(conf->log));
1696                                         if (dev->page != dev->orig_page &&
1697                                             !r5c_is_writeback(conf->log)) {
1698                                                 set_bit(R5_SkipCopy, &dev->flags);
1699                                                 clear_bit(R5_UPTODATE, &dev->flags);
1700                                                 clear_bit(R5_OVERWRITE, &dev->flags);
1701                                         }
1702                                 }
1703                                 wbi = r5_next_bio(wbi, dev->sector);
1704                         }
1705
1706                         if (head_sh->batch_head) {
1707                                 sh = list_first_entry(&sh->batch_list,
1708                                                       struct stripe_head,
1709                                                       batch_list);
1710                                 if (sh == head_sh)
1711                                         continue;
1712                                 goto again;
1713                         }
1714                 }
1715         }
1716
1717         return tx;
1718 }
1719
1720 static void ops_complete_reconstruct(void *stripe_head_ref)
1721 {
1722         struct stripe_head *sh = stripe_head_ref;
1723         int disks = sh->disks;
1724         int pd_idx = sh->pd_idx;
1725         int qd_idx = sh->qd_idx;
1726         int i;
1727         bool fua = false, sync = false, discard = false;
1728
1729         pr_debug("%s: stripe %llu\n", __func__,
1730                 (unsigned long long)sh->sector);
1731
1732         for (i = disks; i--; ) {
1733                 fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1734                 sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1735                 discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1736         }
1737
1738         for (i = disks; i--; ) {
1739                 struct r5dev *dev = &sh->dev[i];
1740
1741                 if (dev->written || i == pd_idx || i == qd_idx) {
1742                         if (!discard && !test_bit(R5_SkipCopy, &dev->flags))
1743                                 set_bit(R5_UPTODATE, &dev->flags);
1744                         if (fua)
1745                                 set_bit(R5_WantFUA, &dev->flags);
1746                         if (sync)
1747                                 set_bit(R5_SyncIO, &dev->flags);
1748                 }
1749         }
1750
1751         if (sh->reconstruct_state == reconstruct_state_drain_run)
1752                 sh->reconstruct_state = reconstruct_state_drain_result;
1753         else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1754                 sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1755         else {
1756                 BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1757                 sh->reconstruct_state = reconstruct_state_result;
1758         }
1759
1760         set_bit(STRIPE_HANDLE, &sh->state);
1761         raid5_release_stripe(sh);
1762 }
1763
1764 static void
1765 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1766                      struct dma_async_tx_descriptor *tx)
1767 {
1768         int disks = sh->disks;
1769         struct page **xor_srcs;
1770         struct async_submit_ctl submit;
1771         int count, pd_idx = sh->pd_idx, i;
1772         struct page *xor_dest;
1773         int prexor = 0;
1774         unsigned long flags;
1775         int j = 0;
1776         struct stripe_head *head_sh = sh;
1777         int last_stripe;
1778
1779         pr_debug("%s: stripe %llu\n", __func__,
1780                 (unsigned long long)sh->sector);
1781
1782         for (i = 0; i < sh->disks; i++) {
1783                 if (pd_idx == i)
1784                         continue;
1785                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1786                         break;
1787         }
1788         if (i >= sh->disks) {
1789                 atomic_inc(&sh->count);
1790                 set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1791                 ops_complete_reconstruct(sh);
1792                 return;
1793         }
1794 again:
1795         count = 0;
1796         xor_srcs = to_addr_page(percpu, j);
1797         /* check if prexor is active which means only process blocks
1798          * that are part of a read-modify-write (written)
1799          */
1800         if (head_sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1801                 prexor = 1;
1802                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1803                 for (i = disks; i--; ) {
1804                         struct r5dev *dev = &sh->dev[i];
1805                         if (head_sh->dev[i].written ||
1806                             test_bit(R5_InJournal, &head_sh->dev[i].flags))
1807                                 xor_srcs[count++] = dev->page;
1808                 }
1809         } else {
1810                 xor_dest = sh->dev[pd_idx].page;
1811                 for (i = disks; i--; ) {
1812                         struct r5dev *dev = &sh->dev[i];
1813                         if (i != pd_idx)
1814                                 xor_srcs[count++] = dev->page;
1815                 }
1816         }
1817
1818         /* 1/ if we prexor'd then the dest is reused as a source
1819          * 2/ if we did not prexor then we are redoing the parity
1820          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1821          * for the synchronous xor case
1822          */
1823         last_stripe = !head_sh->batch_head ||
1824                 list_first_entry(&sh->batch_list,
1825                                  struct stripe_head, batch_list) == head_sh;
1826         if (last_stripe) {
1827                 flags = ASYNC_TX_ACK |
1828                         (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1829
1830                 atomic_inc(&head_sh->count);
1831                 init_async_submit(&submit, flags, tx, ops_complete_reconstruct, head_sh,
1832                                   to_addr_conv(sh, percpu, j));
1833         } else {
1834                 flags = prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST;
1835                 init_async_submit(&submit, flags, tx, NULL, NULL,
1836                                   to_addr_conv(sh, percpu, j));
1837         }
1838
1839         if (unlikely(count == 1))
1840                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1841         else
1842                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1843         if (!last_stripe) {
1844                 j++;
1845                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1846                                       batch_list);
1847                 goto again;
1848         }
1849 }
1850
1851 static void
1852 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1853                      struct dma_async_tx_descriptor *tx)
1854 {
1855         struct async_submit_ctl submit;
1856         struct page **blocks;
1857         int count, i, j = 0;
1858         struct stripe_head *head_sh = sh;
1859         int last_stripe;
1860         int synflags;
1861         unsigned long txflags;
1862
1863         pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1864
1865         for (i = 0; i < sh->disks; i++) {
1866                 if (sh->pd_idx == i || sh->qd_idx == i)
1867                         continue;
1868                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1869                         break;
1870         }
1871         if (i >= sh->disks) {
1872                 atomic_inc(&sh->count);
1873                 set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1874                 set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1875                 ops_complete_reconstruct(sh);
1876                 return;
1877         }
1878
1879 again:
1880         blocks = to_addr_page(percpu, j);
1881
1882         if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1883                 synflags = SYNDROME_SRC_WRITTEN;
1884                 txflags = ASYNC_TX_ACK | ASYNC_TX_PQ_XOR_DST;
1885         } else {
1886                 synflags = SYNDROME_SRC_ALL;
1887                 txflags = ASYNC_TX_ACK;
1888         }
1889
1890         count = set_syndrome_sources(blocks, sh, synflags);
1891         last_stripe = !head_sh->batch_head ||
1892                 list_first_entry(&sh->batch_list,
1893                                  struct stripe_head, batch_list) == head_sh;
1894
1895         if (last_stripe) {
1896                 atomic_inc(&head_sh->count);
1897                 init_async_submit(&submit, txflags, tx, ops_complete_reconstruct,
1898                                   head_sh, to_addr_conv(sh, percpu, j));
1899         } else
1900                 init_async_submit(&submit, 0, tx, NULL, NULL,
1901                                   to_addr_conv(sh, percpu, j));
1902         tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1903         if (!last_stripe) {
1904                 j++;
1905                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1906                                       batch_list);
1907                 goto again;
1908         }
1909 }
1910
1911 static void ops_complete_check(void *stripe_head_ref)
1912 {
1913         struct stripe_head *sh = stripe_head_ref;
1914
1915         pr_debug("%s: stripe %llu\n", __func__,
1916                 (unsigned long long)sh->sector);
1917
1918         sh->check_state = check_state_check_result;
1919         set_bit(STRIPE_HANDLE, &sh->state);
1920         raid5_release_stripe(sh);
1921 }
1922
1923 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1924 {
1925         int disks = sh->disks;
1926         int pd_idx = sh->pd_idx;
1927         int qd_idx = sh->qd_idx;
1928         struct page *xor_dest;
1929         struct page **xor_srcs = to_addr_page(percpu, 0);
1930         struct dma_async_tx_descriptor *tx;
1931         struct async_submit_ctl submit;
1932         int count;
1933         int i;
1934
1935         pr_debug("%s: stripe %llu\n", __func__,
1936                 (unsigned long long)sh->sector);
1937
1938         BUG_ON(sh->batch_head);
1939         count = 0;
1940         xor_dest = sh->dev[pd_idx].page;
1941         xor_srcs[count++] = xor_dest;
1942         for (i = disks; i--; ) {
1943                 if (i == pd_idx || i == qd_idx)
1944                         continue;
1945                 xor_srcs[count++] = sh->dev[i].page;
1946         }
1947
1948         init_async_submit(&submit, 0, NULL, NULL, NULL,
1949                           to_addr_conv(sh, percpu, 0));
1950         tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1951                            &sh->ops.zero_sum_result, &submit);
1952
1953         atomic_inc(&sh->count);
1954         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1955         tx = async_trigger_callback(&submit);
1956 }
1957
1958 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1959 {
1960         struct page **srcs = to_addr_page(percpu, 0);
1961         struct async_submit_ctl submit;
1962         int count;
1963
1964         pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1965                 (unsigned long long)sh->sector, checkp);
1966
1967         BUG_ON(sh->batch_head);
1968         count = set_syndrome_sources(srcs, sh, SYNDROME_SRC_ALL);
1969         if (!checkp)
1970                 srcs[count] = NULL;
1971
1972         atomic_inc(&sh->count);
1973         init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1974                           sh, to_addr_conv(sh, percpu, 0));
1975         async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1976                            &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1977 }
1978
1979 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1980 {
1981         int overlap_clear = 0, i, disks = sh->disks;
1982         struct dma_async_tx_descriptor *tx = NULL;
1983         struct r5conf *conf = sh->raid_conf;
1984         int level = conf->level;
1985         struct raid5_percpu *percpu;
1986         unsigned long cpu;
1987
1988         cpu = get_cpu();
1989         percpu = per_cpu_ptr(conf->percpu, cpu);
1990         if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1991                 ops_run_biofill(sh);
1992                 overlap_clear++;
1993         }
1994
1995         if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1996                 if (level < 6)
1997                         tx = ops_run_compute5(sh, percpu);
1998                 else {
1999                         if (sh->ops.target2 < 0 || sh->ops.target < 0)
2000                                 tx = ops_run_compute6_1(sh, percpu);
2001                         else
2002                                 tx = ops_run_compute6_2(sh, percpu);
2003                 }
2004                 /* terminate the chain if reconstruct is not set to be run */
2005                 if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
2006                         async_tx_ack(tx);
2007         }
2008
2009         if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
2010                 if (level < 6)
2011                         tx = ops_run_prexor5(sh, percpu, tx);
2012                 else
2013                         tx = ops_run_prexor6(sh, percpu, tx);
2014         }
2015
2016         if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
2017                 tx = ops_run_biodrain(sh, tx);
2018                 overlap_clear++;
2019         }
2020
2021         if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
2022                 if (level < 6)
2023                         ops_run_reconstruct5(sh, percpu, tx);
2024                 else
2025                         ops_run_reconstruct6(sh, percpu, tx);
2026         }
2027
2028         if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
2029                 if (sh->check_state == check_state_run)
2030                         ops_run_check_p(sh, percpu);
2031                 else if (sh->check_state == check_state_run_q)
2032                         ops_run_check_pq(sh, percpu, 0);
2033                 else if (sh->check_state == check_state_run_pq)
2034                         ops_run_check_pq(sh, percpu, 1);
2035                 else
2036                         BUG();
2037         }
2038
2039         if (overlap_clear && !sh->batch_head)
2040                 for (i = disks; i--; ) {
2041                         struct r5dev *dev = &sh->dev[i];
2042                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
2043                                 wake_up(&sh->raid_conf->wait_for_overlap);
2044                 }
2045         put_cpu();
2046 }
2047
2048 static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp,
2049         int disks)
2050 {
2051         struct stripe_head *sh;
2052         int i;
2053
2054         sh = kmem_cache_zalloc(sc, gfp);
2055         if (sh) {
2056                 spin_lock_init(&sh->stripe_lock);
2057                 spin_lock_init(&sh->batch_lock);
2058                 INIT_LIST_HEAD(&sh->batch_list);
2059                 INIT_LIST_HEAD(&sh->lru);
2060                 INIT_LIST_HEAD(&sh->r5c);
2061                 INIT_LIST_HEAD(&sh->log_list);
2062                 atomic_set(&sh->count, 1);
2063                 sh->log_start = MaxSector;
2064                 for (i = 0; i < disks; i++) {
2065                         struct r5dev *dev = &sh->dev[i];
2066
2067                         bio_init(&dev->req, &dev->vec, 1);
2068                         bio_init(&dev->rreq, &dev->rvec, 1);
2069                 }
2070         }
2071         return sh;
2072 }
2073 static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
2074 {
2075         struct stripe_head *sh;
2076
2077         sh = alloc_stripe(conf->slab_cache, gfp, conf->pool_size);
2078         if (!sh)
2079                 return 0;
2080
2081         sh->raid_conf = conf;
2082
2083         if (grow_buffers(sh, gfp)) {
2084                 shrink_buffers(sh);
2085                 kmem_cache_free(conf->slab_cache, sh);
2086                 return 0;
2087         }
2088         sh->hash_lock_index =
2089                 conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
2090         /* we just created an active stripe so... */
2091         atomic_inc(&conf->active_stripes);
2092
2093         raid5_release_stripe(sh);
2094         conf->max_nr_stripes++;
2095         return 1;
2096 }
2097
2098 static int grow_stripes(struct r5conf *conf, int num)
2099 {
2100         struct kmem_cache *sc;
2101         int devs = max(conf->raid_disks, conf->previous_raid_disks);
2102
2103         if (conf->mddev->gendisk)
2104                 sprintf(conf->cache_name[0],
2105                         "raid%d-%s", conf->level, mdname(conf->mddev));
2106         else
2107                 sprintf(conf->cache_name[0],
2108                         "raid%d-%p", conf->level, conf->mddev);
2109         sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
2110
2111         conf->active_name = 0;
2112         sc = kmem_cache_create(conf->cache_name[conf->active_name],
2113                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
2114                                0, 0, NULL);
2115         if (!sc)
2116                 return 1;
2117         conf->slab_cache = sc;
2118         conf->pool_size = devs;
2119         while (num--)
2120                 if (!grow_one_stripe(conf, GFP_KERNEL))
2121                         return 1;
2122
2123         return 0;
2124 }
2125
2126 /**
2127  * scribble_len - return the required size of the scribble region
2128  * @num - total number of disks in the array
2129  *
2130  * The size must be enough to contain:
2131  * 1/ a struct page pointer for each device in the array +2
2132  * 2/ room to convert each entry in (1) to its corresponding dma
2133  *    (dma_map_page()) or page (page_address()) address.
2134  *
2135  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
2136  * calculate over all devices (not just the data blocks), using zeros in place
2137  * of the P and Q blocks.
2138  */
2139 static struct flex_array *scribble_alloc(int num, int cnt, gfp_t flags)
2140 {
2141         struct flex_array *ret;
2142         size_t len;
2143
2144         len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
2145         ret = flex_array_alloc(len, cnt, flags);
2146         if (!ret)
2147                 return NULL;
2148         /* always prealloc all elements, so no locking is required */
2149         if (flex_array_prealloc(ret, 0, cnt, flags)) {
2150                 flex_array_free(ret);
2151                 return NULL;
2152         }
2153         return ret;
2154 }
2155
2156 static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
2157 {
2158         unsigned long cpu;
2159         int err = 0;
2160
2161         /*
2162          * Never shrink. And mddev_suspend() could deadlock if this is called
2163          * from raid5d. In that case, scribble_disks and scribble_sectors
2164          * should equal to new_disks and new_sectors
2165          */
2166         if (conf->scribble_disks >= new_disks &&
2167             conf->scribble_sectors >= new_sectors)
2168                 return 0;
2169         mddev_suspend(conf->mddev);
2170         get_online_cpus();
2171         for_each_present_cpu(cpu) {
2172                 struct raid5_percpu *percpu;
2173                 struct flex_array *scribble;
2174
2175                 percpu = per_cpu_ptr(conf->percpu, cpu);
2176                 scribble = scribble_alloc(new_disks,
2177                                           new_sectors / STRIPE_SECTORS,
2178                                           GFP_NOIO);
2179
2180                 if (scribble) {
2181                         flex_array_free(percpu->scribble);
2182                         percpu->scribble = scribble;
2183                 } else {
2184                         err = -ENOMEM;
2185                         break;
2186                 }
2187         }
2188         put_online_cpus();
2189         mddev_resume(conf->mddev);
2190         if (!err) {
2191                 conf->scribble_disks = new_disks;
2192                 conf->scribble_sectors = new_sectors;
2193         }
2194         return err;
2195 }
2196
2197 static int resize_stripes(struct r5conf *conf, int newsize)
2198 {
2199         /* Make all the stripes able to hold 'newsize' devices.
2200          * New slots in each stripe get 'page' set to a new page.
2201          *
2202          * This happens in stages:
2203          * 1/ create a new kmem_cache and allocate the required number of
2204          *    stripe_heads.
2205          * 2/ gather all the old stripe_heads and transfer the pages across
2206          *    to the new stripe_heads.  This will have the side effect of
2207          *    freezing the array as once all stripe_heads have been collected,
2208          *    no IO will be possible.  Old stripe heads are freed once their
2209          *    pages have been transferred over, and the old kmem_cache is
2210          *    freed when all stripes are done.
2211          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
2212          *    we simple return a failre status - no need to clean anything up.
2213          * 4/ allocate new pages for the new slots in the new stripe_heads.
2214          *    If this fails, we don't bother trying the shrink the
2215          *    stripe_heads down again, we just leave them as they are.
2216          *    As each stripe_head is processed the new one is released into
2217          *    active service.
2218          *
2219          * Once step2 is started, we cannot afford to wait for a write,
2220          * so we use GFP_NOIO allocations.
2221          */
2222         struct stripe_head *osh, *nsh;
2223         LIST_HEAD(newstripes);
2224         struct disk_info *ndisks;
2225         int err;
2226         struct kmem_cache *sc;
2227         int i;
2228         int hash, cnt;
2229
2230         if (newsize <= conf->pool_size)
2231                 return 0; /* never bother to shrink */
2232
2233         err = md_allow_write(conf->mddev);
2234         if (err)
2235                 return err;
2236
2237         /* Step 1 */
2238         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
2239                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
2240                                0, 0, NULL);
2241         if (!sc)
2242                 return -ENOMEM;
2243
2244         /* Need to ensure auto-resizing doesn't interfere */
2245         mutex_lock(&conf->cache_size_mutex);
2246
2247         for (i = conf->max_nr_stripes; i; i--) {
2248                 nsh = alloc_stripe(sc, GFP_KERNEL, newsize);
2249                 if (!nsh)
2250                         break;
2251
2252                 nsh->raid_conf = conf;
2253                 list_add(&nsh->lru, &newstripes);
2254         }
2255         if (i) {
2256                 /* didn't get enough, give up */
2257                 while (!list_empty(&newstripes)) {
2258                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
2259                         list_del(&nsh->lru);
2260                         kmem_cache_free(sc, nsh);
2261                 }
2262                 kmem_cache_destroy(sc);
2263                 mutex_unlock(&conf->cache_size_mutex);
2264                 return -ENOMEM;
2265         }
2266         /* Step 2 - Must use GFP_NOIO now.
2267          * OK, we have enough stripes, start collecting inactive
2268          * stripes and copying them over
2269          */
2270         hash = 0;
2271         cnt = 0;
2272         list_for_each_entry(nsh, &newstripes, lru) {
2273                 lock_device_hash_lock(conf, hash);
2274                 wait_event_cmd(conf->wait_for_stripe,
2275                                     !list_empty(conf->inactive_list + hash),
2276                                     unlock_device_hash_lock(conf, hash),
2277                                     lock_device_hash_lock(conf, hash));
2278                 osh = get_free_stripe(conf, hash);
2279                 unlock_device_hash_lock(conf, hash);
2280
2281                 for(i=0; i<conf->pool_size; i++) {
2282                         nsh->dev[i].page = osh->dev[i].page;
2283                         nsh->dev[i].orig_page = osh->dev[i].page;
2284                 }
2285                 nsh->hash_lock_index = hash;
2286                 kmem_cache_free(conf->slab_cache, osh);
2287                 cnt++;
2288                 if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
2289                     !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
2290                         hash++;
2291                         cnt = 0;
2292                 }
2293         }
2294         kmem_cache_destroy(conf->slab_cache);
2295
2296         /* Step 3.
2297          * At this point, we are holding all the stripes so the array
2298          * is completely stalled, so now is a good time to resize
2299          * conf->disks and the scribble region
2300          */
2301         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
2302         if (ndisks) {
2303                 for (i = 0; i < conf->pool_size; i++)
2304                         ndisks[i] = conf->disks[i];
2305
2306                 for (i = conf->pool_size; i < newsize; i++) {
2307                         ndisks[i].extra_page = alloc_page(GFP_NOIO);
2308                         if (!ndisks[i].extra_page)
2309                                 err = -ENOMEM;
2310                 }
2311
2312                 if (err) {
2313                         for (i = conf->pool_size; i < newsize; i++)
2314                                 if (ndisks[i].extra_page)
2315                                         put_page(ndisks[i].extra_page);
2316                         kfree(ndisks);
2317                 } else {
2318                         kfree(conf->disks);
2319                         conf->disks = ndisks;
2320                 }
2321         } else
2322                 err = -ENOMEM;
2323
2324         mutex_unlock(&conf->cache_size_mutex);
2325         /* Step 4, return new stripes to service */
2326         while(!list_empty(&newstripes)) {
2327                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
2328                 list_del_init(&nsh->lru);
2329
2330                 for (i=conf->raid_disks; i < newsize; i++)
2331                         if (nsh->dev[i].page == NULL) {
2332                                 struct page *p = alloc_page(GFP_NOIO);
2333                                 nsh->dev[i].page = p;
2334                                 nsh->dev[i].orig_page = p;
2335                                 if (!p)
2336                                         err = -ENOMEM;
2337                         }
2338                 raid5_release_stripe(nsh);
2339         }
2340         /* critical section pass, GFP_NOIO no longer needed */
2341
2342         conf->slab_cache = sc;
2343         conf->active_name = 1-conf->active_name;
2344         if (!err)
2345                 conf->pool_size = newsize;
2346         return err;
2347 }
2348
2349 static int drop_one_stripe(struct r5conf *conf)
2350 {
2351         struct stripe_head *sh;
2352         int hash = (conf->max_nr_stripes - 1) & STRIPE_HASH_LOCKS_MASK;
2353
2354         spin_lock_irq(conf->hash_locks + hash);
2355         sh = get_free_stripe(conf, hash);
2356         spin_unlock_irq(conf->hash_locks + hash);
2357         if (!sh)
2358                 return 0;
2359         BUG_ON(atomic_read(&sh->count));
2360         shrink_buffers(sh);
2361         kmem_cache_free(conf->slab_cache, sh);
2362         atomic_dec(&conf->active_stripes);
2363         conf->max_nr_stripes--;
2364         return 1;
2365 }
2366
2367 static void shrink_stripes(struct r5conf *conf)
2368 {
2369         while (conf->max_nr_stripes &&
2370                drop_one_stripe(conf))
2371                 ;
2372
2373         kmem_cache_destroy(conf->slab_cache);
2374         conf->slab_cache = NULL;
2375 }
2376
2377 static void raid5_end_read_request(struct bio * bi)
2378 {
2379         struct stripe_head *sh = bi->bi_private;
2380         struct r5conf *conf = sh->raid_conf;
2381         int disks = sh->disks, i;
2382         char b[BDEVNAME_SIZE];
2383         struct md_rdev *rdev = NULL;
2384         sector_t s;
2385
2386         for (i=0 ; i<disks; i++)
2387                 if (bi == &sh->dev[i].req)
2388                         break;
2389
2390         pr_debug("end_read_request %llu/%d, count: %d, error %d.\n",
2391                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
2392                 bi->bi_error);
2393         if (i == disks) {
2394                 bio_reset(bi);
2395                 BUG();
2396                 return;
2397         }
2398         if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2399                 /* If replacement finished while this request was outstanding,
2400                  * 'replacement' might be NULL already.
2401                  * In that case it moved down to 'rdev'.
2402                  * rdev is not removed until all requests are finished.
2403                  */
2404                 rdev = conf->disks[i].replacement;
2405         if (!rdev)
2406                 rdev = conf->disks[i].rdev;
2407
2408         if (use_new_offset(conf, sh))
2409                 s = sh->sector + rdev->new_data_offset;
2410         else
2411                 s = sh->sector + rdev->data_offset;
2412         if (!bi->bi_error) {
2413                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
2414                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2415                         /* Note that this cannot happen on a
2416                          * replacement device.  We just fail those on
2417                          * any error
2418                          */
2419                         pr_info_ratelimited(
2420                                 "md/raid:%s: read error corrected (%lu sectors at %llu on %s)\n",
2421                                 mdname(conf->mddev), STRIPE_SECTORS,
2422                                 (unsigned long long)s,
2423                                 bdevname(rdev->bdev, b));
2424                         atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2425                         clear_bit(R5_ReadError, &sh->dev[i].flags);
2426                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
2427                 } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2428                         clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2429
2430                 if (test_bit(R5_InJournal, &sh->dev[i].flags))
2431                         /*
2432                          * end read for a page in journal, this
2433                          * must be preparing for prexor in rmw
2434                          */
2435                         set_bit(R5_OrigPageUPTDODATE, &sh->dev[i].flags);
2436
2437                 if (atomic_read(&rdev->read_errors))
2438                         atomic_set(&rdev->read_errors, 0);
2439         } else {
2440                 const char *bdn = bdevname(rdev->bdev, b);
2441                 int retry = 0;
2442                 int set_bad = 0;
2443
2444                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2445                 atomic_inc(&rdev->read_errors);
2446                 if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2447                         pr_warn_ratelimited(
2448                                 "md/raid:%s: read error on replacement device (sector %llu on %s).\n",
2449                                 mdname(conf->mddev),
2450                                 (unsigned long long)s,
2451                                 bdn);
2452                 else if (conf->mddev->degraded >= conf->max_degraded) {
2453                         set_bad = 1;
2454                         pr_warn_ratelimited(
2455                                 "md/raid:%s: read error not correctable (sector %llu on %s).\n",
2456                                 mdname(conf->mddev),
2457                                 (unsigned long long)s,
2458                                 bdn);
2459                 } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2460                         /* Oh, no!!! */
2461                         set_bad = 1;
2462                         pr_warn_ratelimited(
2463                                 "md/raid:%s: read error NOT corrected!! (sector %llu on %s).\n",
2464                                 mdname(conf->mddev),
2465                                 (unsigned long long)s,
2466                                 bdn);
2467                 } else if (atomic_read(&rdev->read_errors)
2468                          > conf->max_nr_stripes)
2469                         pr_warn("md/raid:%s: Too many read errors, failing device %s.\n",
2470                                mdname(conf->mddev), bdn);
2471                 else
2472                         retry = 1;
2473                 if (set_bad && test_bit(In_sync, &rdev->flags)
2474                     && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2475                         retry = 1;
2476                 if (retry)
2477                         if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2478                                 set_bit(R5_ReadError, &sh->dev[i].flags);
2479                                 clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2480                         } else
2481                                 set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2482                 else {
2483                         clear_bit(R5_ReadError, &sh->dev[i].flags);
2484                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
2485                         if (!(set_bad
2486                               && test_bit(In_sync, &rdev->flags)
2487                               && rdev_set_badblocks(
2488                                       rdev, sh->sector, STRIPE_SECTORS, 0)))
2489                                 md_error(conf->mddev, rdev);
2490                 }
2491         }
2492         rdev_dec_pending(rdev, conf->mddev);
2493         bio_reset(bi);
2494         clear_bit(R5_LOCKED, &sh->dev[i].flags);
2495         set_bit(STRIPE_HANDLE, &sh->state);
2496         raid5_release_stripe(sh);
2497 }
2498
2499 static void raid5_end_write_request(struct bio *bi)
2500 {
2501         struct stripe_head *sh = bi->bi_private;
2502         struct r5conf *conf = sh->raid_conf;
2503         int disks = sh->disks, i;
2504         struct md_rdev *uninitialized_var(rdev);
2505         sector_t first_bad;
2506         int bad_sectors;
2507         int replacement = 0;
2508
2509         for (i = 0 ; i < disks; i++) {
2510                 if (bi == &sh->dev[i].req) {
2511                         rdev = conf->disks[i].rdev;
2512                         break;
2513                 }
2514                 if (bi == &sh->dev[i].rreq) {
2515                         rdev = conf->disks[i].replacement;
2516                         if (rdev)
2517                                 replacement = 1;
2518                         else
2519                                 /* rdev was removed and 'replacement'
2520                                  * replaced it.  rdev is not removed
2521                                  * until all requests are finished.
2522                                  */
2523                                 rdev = conf->disks[i].rdev;
2524                         break;
2525                 }
2526         }
2527         pr_debug("end_write_request %llu/%d, count %d, error: %d.\n",
2528                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
2529                 bi->bi_error);
2530         if (i == disks) {
2531                 bio_reset(bi);
2532                 BUG();
2533                 return;
2534         }
2535
2536         if (replacement) {
2537                 if (bi->bi_error)
2538                         md_error(conf->mddev, rdev);
2539                 else if (is_badblock(rdev, sh->sector,
2540                                      STRIPE_SECTORS,
2541                                      &first_bad, &bad_sectors))
2542                         set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2543         } else {
2544                 if (bi->bi_error) {
2545                         set_bit(STRIPE_DEGRADED, &sh->state);
2546                         set_bit(WriteErrorSeen, &rdev->flags);
2547                         set_bit(R5_WriteError, &sh->dev[i].flags);
2548                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
2549                                 set_bit(MD_RECOVERY_NEEDED,
2550                                         &rdev->mddev->recovery);
2551                 } else if (is_badblock(rdev, sh->sector,
2552                                        STRIPE_SECTORS,
2553                                        &first_bad, &bad_sectors)) {
2554                         set_bit(R5_MadeGood, &sh->dev[i].flags);
2555                         if (test_bit(R5_ReadError, &sh->dev[i].flags))
2556                                 /* That was a successful write so make
2557                                  * sure it looks like we already did
2558                                  * a re-write.
2559                                  */
2560                                 set_bit(R5_ReWrite, &sh->dev[i].flags);
2561                 }
2562         }
2563         rdev_dec_pending(rdev, conf->mddev);
2564
2565         if (sh->batch_head && bi->bi_error && !replacement)
2566                 set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);
2567
2568         bio_reset(bi);
2569         if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2570                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
2571         set_bit(STRIPE_HANDLE, &sh->state);
2572         raid5_release_stripe(sh);
2573
2574         if (sh->batch_head && sh != sh->batch_head)
2575                 raid5_release_stripe(sh->batch_head);
2576 }
2577
2578 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
2579 {
2580         struct r5dev *dev = &sh->dev[i];
2581
2582         dev->flags = 0;
2583         dev->sector = raid5_compute_blocknr(sh, i, previous);
2584 }
2585
2586 static void raid5_error(struct mddev *mddev, struct md_rdev *rdev)
2587 {
2588         char b[BDEVNAME_SIZE];
2589         struct r5conf *conf = mddev->private;
2590         unsigned long flags;
2591         pr_debug("raid456: error called\n");
2592
2593         spin_lock_irqsave(&conf->device_lock, flags);
2594         clear_bit(In_sync, &rdev->flags);
2595         mddev->degraded = raid5_calc_degraded(conf);
2596         spin_unlock_irqrestore(&conf->device_lock, flags);
2597         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2598
2599         set_bit(Blocked, &rdev->flags);
2600         set_bit(Faulty, &rdev->flags);
2601         set_mask_bits(&mddev->sb_flags, 0,
2602                       BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING));
2603         pr_crit("md/raid:%s: Disk failure on %s, disabling device.\n"
2604                 "md/raid:%s: Operation continuing on %d devices.\n",
2605                 mdname(mddev),
2606                 bdevname(rdev->bdev, b),
2607                 mdname(mddev),
2608                 conf->raid_disks - mddev->degraded);
2609         r5c_update_on_rdev_error(mddev);
2610 }
2611
2612 /*
2613  * Input: a 'big' sector number,
2614  * Output: index of the data and parity disk, and the sector # in them.
2615  */
2616 sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2617                               int previous, int *dd_idx,
2618                               struct stripe_head *sh)
2619 {
2620         sector_t stripe, stripe2;
2621         sector_t chunk_number;
2622         unsigned int chunk_offset;
2623         int pd_idx, qd_idx;
2624         int ddf_layout = 0;
2625         sector_t new_sector;
2626         int algorithm = previous ? conf->prev_algo
2627                                  : conf->algorithm;
2628         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2629                                          : conf->chunk_sectors;
2630         int raid_disks = previous ? conf->previous_raid_disks
2631                                   : conf->raid_disks;
2632         int data_disks = raid_disks - conf->max_degraded;
2633
2634         /* First compute the information on this sector */
2635
2636         /*
2637          * Compute the chunk number and the sector offset inside the chunk
2638          */
2639         chunk_offset = sector_div(r_sector, sectors_per_chunk);
2640         chunk_number = r_sector;
2641
2642         /*
2643          * Compute the stripe number
2644          */
2645         stripe = chunk_number;
2646         *dd_idx = sector_div(stripe, data_disks);
2647         stripe2 = stripe;
2648         /*
2649          * Select the parity disk based on the user selected algorithm.
2650          */
2651         pd_idx = qd_idx = -1;
2652         switch(conf->level) {
2653         case 4:
2654                 pd_idx = data_disks;
2655                 break;
2656         case 5:
2657                 switch (algorithm) {
2658                 case ALGORITHM_LEFT_ASYMMETRIC:
2659                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2660                         if (*dd_idx >= pd_idx)
2661                                 (*dd_idx)++;
2662                         break;
2663                 case ALGORITHM_RIGHT_ASYMMETRIC:
2664                         pd_idx = sector_div(stripe2, raid_disks);
2665                         if (*dd_idx >= pd_idx)
2666                                 (*dd_idx)++;
2667                         break;
2668                 case ALGORITHM_LEFT_SYMMETRIC:
2669                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2670                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2671                         break;
2672                 case ALGORITHM_RIGHT_SYMMETRIC:
2673                         pd_idx = sector_div(stripe2, raid_disks);
2674                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2675                         break;
2676                 case ALGORITHM_PARITY_0:
2677                         pd_idx = 0;
2678                         (*dd_idx)++;
2679                         break;
2680                 case ALGORITHM_PARITY_N:
2681                         pd_idx = data_disks;
2682                         break;
2683                 default:
2684                         BUG();
2685                 }
2686                 break;
2687         case 6:
2688
2689                 switch (algorithm) {
2690                 case ALGORITHM_LEFT_ASYMMETRIC:
2691                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2692                         qd_idx = pd_idx + 1;
2693                         if (pd_idx == raid_disks-1) {
2694                                 (*dd_idx)++;    /* Q D D D P */
2695                                 qd_idx = 0;
2696                         } else if (*dd_idx >= pd_idx)
2697                                 (*dd_idx) += 2; /* D D P Q D */
2698                         break;
2699                 case ALGORITHM_RIGHT_ASYMMETRIC:
2700                         pd_idx = sector_div(stripe2, raid_disks);
2701                         qd_idx = pd_idx + 1;
2702                         if (pd_idx == raid_disks-1) {
2703                                 (*dd_idx)++;    /* Q D D D P */
2704                                 qd_idx = 0;
2705                         } else if (*dd_idx >= pd_idx)
2706                                 (*dd_idx) += 2; /* D D P Q D */
2707                         break;
2708                 case ALGORITHM_LEFT_SYMMETRIC:
2709                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2710                         qd_idx = (pd_idx + 1) % raid_disks;
2711                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2712                         break;
2713                 case ALGORITHM_RIGHT_SYMMETRIC:
2714                         pd_idx = sector_div(stripe2, raid_disks);
2715                         qd_idx = (pd_idx + 1) % raid_disks;
2716                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2717                         break;
2718
2719                 case ALGORITHM_PARITY_0:
2720                         pd_idx = 0;
2721                         qd_idx = 1;
2722                         (*dd_idx) += 2;
2723                         break;
2724                 case ALGORITHM_PARITY_N:
2725                         pd_idx = data_disks;
2726                         qd_idx = data_disks + 1;
2727                         break;
2728
2729                 case ALGORITHM_ROTATING_ZERO_RESTART:
2730                         /* Exactly the same as RIGHT_ASYMMETRIC, but or
2731                          * of blocks for computing Q is different.
2732                          */
2733                         pd_idx = sector_div(stripe2, raid_disks);
2734                         qd_idx = pd_idx + 1;
2735                         if (pd_idx == raid_disks-1) {
2736                                 (*dd_idx)++;    /* Q D D D P */
2737                                 qd_idx = 0;
2738                         } else if (*dd_idx >= pd_idx)
2739                                 (*dd_idx) += 2; /* D D P Q D */
2740                         ddf_layout = 1;
2741                         break;
2742
2743                 case ALGORITHM_ROTATING_N_RESTART:
2744                         /* Same a left_asymmetric, by first stripe is
2745                          * D D D P Q  rather than
2746                          * Q D D D P
2747                          */
2748                         stripe2 += 1;
2749                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2750                         qd_idx = pd_idx + 1;
2751                         if (pd_idx == raid_disks-1) {
2752                                 (*dd_idx)++;    /* Q D D D P */
2753                                 qd_idx = 0;
2754                         } else if (*dd_idx >= pd_idx)
2755                                 (*dd_idx) += 2; /* D D P Q D */
2756                         ddf_layout = 1;
2757                         break;
2758
2759                 case ALGORITHM_ROTATING_N_CONTINUE:
2760                         /* Same as left_symmetric but Q is before P */
2761                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2762                         qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2763                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2764                         ddf_layout = 1;
2765                         break;
2766
2767                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2768                         /* RAID5 left_asymmetric, with Q on last device */
2769                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2770                         if (*dd_idx >= pd_idx)
2771                                 (*dd_idx)++;
2772                         qd_idx = raid_disks - 1;
2773                         break;
2774
2775                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2776                         pd_idx = sector_div(stripe2, raid_disks-1);
2777                         if (*dd_idx >= pd_idx)
2778                                 (*dd_idx)++;
2779                         qd_idx = raid_disks - 1;
2780                         break;
2781
2782                 case ALGORITHM_LEFT_SYMMETRIC_6:
2783                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2784                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2785                         qd_idx = raid_disks - 1;
2786                         break;
2787
2788                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2789                         pd_idx = sector_div(stripe2, raid_disks-1);
2790                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2791                         qd_idx = raid_disks - 1;
2792                         break;
2793
2794                 case ALGORITHM_PARITY_0_6:
2795                         pd_idx = 0;
2796                         (*dd_idx)++;
2797                         qd_idx = raid_disks - 1;
2798                         break;
2799
2800                 default:
2801                         BUG();
2802                 }
2803                 break;
2804         }
2805
2806         if (sh) {
2807                 sh->pd_idx = pd_idx;
2808                 sh->qd_idx = qd_idx;
2809                 sh->ddf_layout = ddf_layout;
2810         }
2811         /*
2812          * Finally, compute the new sector number
2813          */
2814         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2815         return new_sector;
2816 }
2817
2818 sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous)
2819 {
2820         struct r5conf *conf = sh->raid_conf;
2821         int raid_disks = sh->disks;
2822         int data_disks = raid_disks - conf->max_degraded;
2823         sector_t new_sector = sh->sector, check;
2824         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2825                                          : conf->chunk_sectors;
2826         int algorithm = previous ? conf->prev_algo
2827                                  : conf->algorithm;
2828         sector_t stripe;
2829         int chunk_offset;
2830         sector_t chunk_number;
2831         int dummy1, dd_idx = i;
2832         sector_t r_sector;
2833         struct stripe_head sh2;
2834
2835         chunk_offset = sector_div(new_sector, sectors_per_chunk);
2836         stripe = new_sector;
2837
2838         if (i == sh->pd_idx)
2839                 return 0;
2840         switch(conf->level) {
2841         case 4: break;
2842         case 5:
2843                 switch (algorithm) {
2844                 case ALGORITHM_LEFT_ASYMMETRIC:
2845                 case ALGORITHM_RIGHT_ASYMMETRIC:
2846                         if (i > sh->pd_idx)
2847                                 i--;
2848                         break;
2849                 case ALGORITHM_LEFT_SYMMETRIC:
2850                 case ALGORITHM_RIGHT_SYMMETRIC:
2851                         if (i < sh->pd_idx)
2852                                 i += raid_disks;
2853                         i -= (sh->pd_idx + 1);
2854                         break;
2855                 case ALGORITHM_PARITY_0:
2856                         i -= 1;
2857                         break;
2858                 case ALGORITHM_PARITY_N:
2859                         break;
2860                 default:
2861                         BUG();
2862                 }
2863                 break;
2864         case 6:
2865                 if (i == sh->qd_idx)
2866                         return 0; /* It is the Q disk */
2867                 switch (algorithm) {
2868                 case ALGORITHM_LEFT_ASYMMETRIC:
2869                 case ALGORITHM_RIGHT_ASYMMETRIC:
2870                 case ALGORITHM_ROTATING_ZERO_RESTART:
2871                 case ALGORITHM_ROTATING_N_RESTART:
2872                         if (sh->pd_idx == raid_disks-1)
2873                                 i--;    /* Q D D D P */
2874                         else if (i > sh->pd_idx)
2875                                 i -= 2; /* D D P Q D */
2876                         break;
2877                 case ALGORITHM_LEFT_SYMMETRIC:
2878                 case ALGORITHM_RIGHT_SYMMETRIC:
2879                         if (sh->pd_idx == raid_disks-1)
2880                                 i--; /* Q D D D P */
2881                         else {
2882                                 /* D D P Q D */
2883                                 if (i < sh->pd_idx)
2884                                         i += raid_disks;
2885                                 i -= (sh->pd_idx + 2);
2886                         }
2887                         break;
2888                 case ALGORITHM_PARITY_0:
2889                         i -= 2;
2890                         break;
2891                 case ALGORITHM_PARITY_N:
2892                         break;
2893                 case ALGORITHM_ROTATING_N_CONTINUE:
2894                         /* Like left_symmetric, but P is before Q */
2895                         if (sh->pd_idx == 0)
2896                                 i--;    /* P D D D Q */
2897                         else {
2898                                 /* D D Q P D */
2899                                 if (i < sh->pd_idx)
2900                                         i += raid_disks;
2901                                 i -= (sh->pd_idx + 1);
2902                         }
2903                         break;
2904                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2905                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2906                         if (i > sh->pd_idx)
2907                                 i--;
2908                         break;
2909                 case ALGORITHM_LEFT_SYMMETRIC_6:
2910                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2911                         if (i < sh->pd_idx)
2912                                 i += data_disks + 1;
2913                         i -= (sh->pd_idx + 1);
2914                         break;
2915                 case ALGORITHM_PARITY_0_6:
2916                         i -= 1;
2917                         break;
2918                 default:
2919                         BUG();
2920                 }
2921                 break;
2922         }
2923
2924         chunk_number = stripe * data_disks + i;
2925         r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2926
2927         check = raid5_compute_sector(conf, r_sector,
2928                                      previous, &dummy1, &sh2);
2929         if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2930                 || sh2.qd_idx != sh->qd_idx) {
2931                 pr_warn("md/raid:%s: compute_blocknr: map not correct\n",
2932                         mdname(conf->mddev));
2933                 return 0;
2934         }
2935         return r_sector;
2936 }
2937
2938 /*
2939  * There are cases where we want handle_stripe_dirtying() and
2940  * schedule_reconstruction() to delay towrite to some dev of a stripe.
2941  *
2942  * This function checks whether we want to delay the towrite. Specifically,
2943  * we delay the towrite when:
2944  *
2945  *   1. degraded stripe has a non-overwrite to the missing dev, AND this
2946  *      stripe has data in journal (for other devices).
2947  *
2948  *      In this case, when reading data for the non-overwrite dev, it is
2949  *      necessary to handle complex rmw of write back cache (prexor with
2950  *      orig_page, and xor with page). To keep read path simple, we would
2951  *      like to flush data in journal to RAID disks first, so complex rmw
2952  *      is handled in the write patch (handle_stripe_dirtying).
2953  *
2954  *   2. when journal space is critical (R5C_LOG_CRITICAL=1)
2955  *
2956  *      It is important to be able to flush all stripes in raid5-cache.
2957  *      Therefore, we need reserve some space on the journal device for
2958  *      these flushes. If flush operation includes pending writes to the
2959  *      stripe, we need to reserve (conf->raid_disk + 1) pages per stripe
2960  *      for the flush out. If we exclude these pending writes from flush
2961  *      operation, we only need (conf->max_degraded + 1) pages per stripe.
2962  *      Therefore, excluding pending writes in these cases enables more
2963  *      efficient use of the journal device.
2964  *
2965  *      Note: To make sure the stripe makes progress, we only delay
2966  *      towrite for stripes with data already in journal (injournal > 0).
2967  *      When LOG_CRITICAL, stripes with injournal == 0 will be sent to
2968  *      no_space_stripes list.
2969  *
2970  */
2971 static inline bool delay_towrite(struct r5conf *conf,
2972                                  struct r5dev *dev,
2973                                  struct stripe_head_state *s)
2974 {
2975         /* case 1 above */
2976         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
2977             !test_bit(R5_Insync, &dev->flags) && s->injournal)
2978                 return true;
2979         /* case 2 above */
2980         if (test_bit(R5C_LOG_CRITICAL, &conf->cache_state) &&
2981             s->injournal > 0)
2982                 return true;
2983         return false;
2984 }
2985
2986 static void
2987 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2988                          int rcw, int expand)
2989 {
2990         int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx, disks = sh->disks;
2991         struct r5conf *conf = sh->raid_conf;
2992         int level = conf->level;
2993
2994         if (rcw) {
2995                 /*
2996                  * In some cases, handle_stripe_dirtying initially decided to
2997                  * run rmw and allocates extra page for prexor. However, rcw is
2998                  * cheaper later on. We need to free the extra page now,
2999                  * because we won't be able to do that in ops_complete_prexor().
3000                  */
3001                 r5c_release_extra_page(sh);
3002
3003                 for (i = disks; i--; ) {
3004                         struct r5dev *dev = &sh->dev[i];
3005
3006                         if (dev->towrite && !delay_towrite(conf, dev, s)) {
3007                                 set_bit(R5_LOCKED, &dev->flags);
3008                                 set_bit(R5_Wantdrain, &dev->flags);
3009                                 if (!expand)
3010                                         clear_bit(R5_UPTODATE, &dev->flags);
3011                                 s->locked++;
3012                         } else if (test_bit(R5_InJournal, &dev->flags)) {
3013                                 set_bit(R5_LOCKED, &dev->flags);
3014                                 s->locked++;
3015                         }
3016                 }
3017                 /* if we are not expanding this is a proper write request, and
3018                  * there will be bios with new data to be drained into the
3019                  * stripe cache
3020                  */
3021                 if (!expand) {
3022                         if (!s->locked)
3023                                 /* False alarm, nothing to do */
3024                                 return;
3025                         sh->reconstruct_state = reconstruct_state_drain_run;
3026                         set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3027                 } else
3028                         sh->reconstruct_state = reconstruct_state_run;
3029
3030                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3031
3032                 if (s->locked + conf->max_degraded == disks)
3033                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
3034                                 atomic_inc(&conf->pending_full_writes);
3035         } else {
3036                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
3037                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
3038                 BUG_ON(level == 6 &&
3039                         (!(test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags) ||
3040                            test_bit(R5_Wantcompute, &sh->dev[qd_idx].flags))));
3041
3042                 for (i = disks; i--; ) {
3043                         struct r5dev *dev = &sh->dev[i];
3044                         if (i == pd_idx || i == qd_idx)
3045                                 continue;
3046
3047                         if (dev->towrite &&
3048                             (test_bit(R5_UPTODATE, &dev->flags) ||
3049                              test_bit(R5_Wantcompute, &dev->flags))) {
3050                                 set_bit(R5_Wantdrain, &dev->flags);
3051                                 set_bit(R5_LOCKED, &dev->flags);
3052                                 clear_bit(R5_UPTODATE, &dev->flags);
3053                                 s->locked++;
3054                         } else if (test_bit(R5_InJournal, &dev->flags)) {
3055                                 set_bit(R5_LOCKED, &dev->flags);
3056                                 s->locked++;
3057                         }
3058                 }
3059                 if (!s->locked)
3060                         /* False alarm - nothing to do */
3061                         return;
3062                 sh->reconstruct_state = reconstruct_state_prexor_drain_run;
3063                 set_bit(STRIPE_OP_PREXOR, &s->ops_request);
3064                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
3065                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
3066         }
3067
3068         /* keep the parity disk(s) locked while asynchronous operations
3069          * are in flight
3070          */
3071         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
3072         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3073         s->locked++;
3074
3075         if (level == 6) {
3076                 int qd_idx = sh->qd_idx;
3077                 struct r5dev *dev = &sh->dev[qd_idx];
3078
3079                 set_bit(R5_LOCKED, &dev->flags);
3080                 clear_bit(R5_UPTODATE, &dev->flags);
3081                 s->locked++;
3082         }
3083
3084         pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
3085                 __func__, (unsigned long long)sh->sector,
3086                 s->locked, s->ops_request);
3087 }
3088
3089 /*
3090  * Each stripe/dev can have one or more bion attached.
3091  * toread/towrite point to the first in a chain.
3092  * The bi_next chain must be in order.
3093  */
3094 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
3095                           int forwrite, int previous)
3096 {
3097         struct bio **bip;
3098         struct r5conf *conf = sh->raid_conf;
3099         int firstwrite=0;
3100
3101         pr_debug("adding bi b#%llu to stripe s#%llu\n",
3102                 (unsigned long long)bi->bi_iter.bi_sector,
3103                 (unsigned long long)sh->sector);
3104
3105         /*
3106          * If several bio share a stripe. The bio bi_phys_segments acts as a
3107          * reference count to avoid race. The reference count should already be
3108          * increased before this function is called (for example, in
3109          * raid5_make_request()), so other bio sharing this stripe will not free the
3110          * stripe. If a stripe is owned by one stripe, the stripe lock will
3111          * protect it.
3112          */
3113         spin_lock_irq(&sh->stripe_lock);
3114         /* Don't allow new IO added to stripes in batch list */
3115         if (sh->batch_head)
3116                 goto overlap;
3117         if (forwrite) {
3118                 bip = &sh->dev[dd_idx].towrite;
3119                 if (*bip == NULL)
3120                         firstwrite = 1;
3121         } else
3122                 bip = &sh->dev[dd_idx].toread;
3123         while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
3124                 if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
3125                         goto overlap;
3126                 bip = & (*bip)->bi_next;
3127         }
3128         if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
3129                 goto overlap;
3130
3131         if (!forwrite || previous)
3132                 clear_bit(STRIPE_BATCH_READY, &sh->state);
3133
3134         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
3135         if (*bip)
3136                 bi->bi_next = *bip;
3137         *bip = bi;
3138         raid5_inc_bi_active_stripes(bi);
3139
3140         if (forwrite) {
3141                 /* check if page is covered */
3142                 sector_t sector = sh->dev[dd_idx].sector;
3143                 for (bi=sh->dev[dd_idx].towrite;
3144                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
3145                              bi && bi->bi_iter.bi_sector <= sector;
3146                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
3147                         if (bio_end_sector(bi) >= sector)
3148                                 sector = bio_end_sector(bi);
3149                 }
3150                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
3151                         if (!test_and_set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags))
3152                                 sh->overwrite_disks++;
3153         }
3154
3155         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
3156                 (unsigned long long)(*bip)->bi_iter.bi_sector,
3157                 (unsigned long long)sh->sector, dd_idx);
3158
3159         if (conf->mddev->bitmap && firstwrite) {
3160                 /* Cannot hold spinlock over bitmap_startwrite,
3161                  * but must ensure this isn't added to a batch until
3162                  * we have added to the bitmap and set bm_seq.
3163                  * So set STRIPE_BITMAP_PENDING to prevent
3164                  * batching.
3165                  * If multiple add_stripe_bio() calls race here they
3166                  * much all set STRIPE_BITMAP_PENDING.  So only the first one
3167                  * to complete "bitmap_startwrite" gets to set
3168                  * STRIPE_BIT_DELAY.  This is important as once a stripe
3169                  * is added to a batch, STRIPE_BIT_DELAY cannot be changed
3170                  * any more.
3171                  */
3172                 set_bit(STRIPE_BITMAP_PENDING, &sh->state);
3173                 spin_unlock_irq(&sh->stripe_lock);
3174                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
3175                                   STRIPE_SECTORS, 0);
3176                 spin_lock_irq(&sh->stripe_lock);
3177                 clear_bit(STRIPE_BITMAP_PENDING, &sh->state);
3178                 if (!sh->batch_head) {
3179                         sh->bm_seq = conf->seq_flush+1;
3180                         set_bit(STRIPE_BIT_DELAY, &sh->state);
3181                 }
3182         }
3183         spin_unlock_irq(&sh->stripe_lock);
3184
3185         if (stripe_can_batch(sh))
3186                 stripe_add_to_batch_list(conf, sh);
3187         return 1;
3188
3189  overlap:
3190         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
3191         spin_unlock_irq(&sh->stripe_lock);
3192         return 0;
3193 }
3194
3195 static void end_reshape(struct r5conf *conf);
3196
3197 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
3198                             struct stripe_head *sh)
3199 {
3200         int sectors_per_chunk =
3201                 previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
3202         int dd_idx;
3203         int chunk_offset = sector_div(stripe, sectors_per_chunk);
3204         int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
3205
3206         raid5_compute_sector(conf,
3207                              stripe * (disks - conf->max_degraded)
3208                              *sectors_per_chunk + chunk_offset,
3209                              previous,
3210                              &dd_idx, sh);
3211 }
3212
3213 static void
3214 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
3215                                 struct stripe_head_state *s, int disks,
3216                                 struct bio_list *return_bi)
3217 {
3218         int i;
3219         BUG_ON(sh->batch_head);
3220         for (i = disks; i--; ) {
3221                 struct bio *bi;
3222                 int bitmap_end = 0;
3223
3224                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
3225                         struct md_rdev *rdev;
3226                         rcu_read_lock();
3227                         rdev = rcu_dereference(conf->disks[i].rdev);
3228                         if (rdev && test_bit(In_sync, &rdev->flags) &&
3229                             !test_bit(Faulty, &rdev->flags))
3230                                 atomic_inc(&rdev->nr_pending);
3231                         else
3232                                 rdev = NULL;
3233                         rcu_read_unlock();
3234                         if (rdev) {
3235                                 if (!rdev_set_badblocks(
3236                                             rdev,
3237                                             sh->sector,
3238                                             STRIPE_SECTORS, 0))
3239                                         md_error(conf->mddev, rdev);
3240                                 rdev_dec_pending(rdev, conf->mddev);
3241                         }
3242                 }
3243                 spin_lock_irq(&sh->stripe_lock);
3244                 /* fail all writes first */
3245                 bi = sh->dev[i].towrite;
3246                 sh->dev[i].towrite = NULL;
3247                 sh->overwrite_disks = 0;
3248                 spin_unlock_irq(&sh->stripe_lock);
3249                 if (bi)
3250                         bitmap_end = 1;
3251
3252                 r5l_stripe_write_finished(sh);
3253
3254                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3255                         wake_up(&conf->wait_for_overlap);
3256
3257                 while (bi && bi->bi_iter.bi_sector <
3258                         sh->dev[i].sector + STRIPE_SECTORS) {
3259                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
3260
3261                         bi->bi_error = -EIO;
3262                         if (!raid5_dec_bi_active_stripes(bi)) {
3263                                 md_write_end(conf->mddev);
3264                                 bio_list_add(return_bi, bi);
3265                         }
3266                         bi = nextbi;
3267                 }
3268                 if (bitmap_end)
3269                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3270                                 STRIPE_SECTORS, 0, 0);
3271                 bitmap_end = 0;
3272                 /* and fail all 'written' */
3273                 bi = sh->dev[i].written;
3274                 sh->dev[i].written = NULL;
3275                 if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
3276                         WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
3277                         sh->dev[i].page = sh->dev[i].orig_page;
3278                 }
3279
3280                 if (bi) bitmap_end = 1;
3281                 while (bi && bi->bi_iter.bi_sector <
3282                        sh->dev[i].sector + STRIPE_SECTORS) {
3283                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
3284
3285                         bi->bi_error = -EIO;
3286                         if (!raid5_dec_bi_active_stripes(bi)) {
3287                                 md_write_end(conf->mddev);
3288                                 bio_list_add(return_bi, bi);
3289                         }
3290                         bi = bi2;
3291                 }
3292
3293                 /* fail any reads if this device is non-operational and
3294                  * the data has not reached the cache yet.
3295                  */
3296                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
3297                     s->failed > conf->max_degraded &&
3298                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
3299                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
3300                         spin_lock_irq(&sh->stripe_lock);
3301                         bi = sh->dev[i].toread;
3302                         sh->dev[i].toread = NULL;
3303                         spin_unlock_irq(&sh->stripe_lock);
3304                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3305                                 wake_up(&conf->wait_for_overlap);
3306                         if (bi)
3307                                 s->to_read--;
3308                         while (bi && bi->bi_iter.bi_sector <
3309                                sh->dev[i].sector + STRIPE_SECTORS) {
3310                                 struct bio *nextbi =
3311                                         r5_next_bio(bi, sh->dev[i].sector);
3312
3313                                 bi->bi_error = -EIO;
3314                                 if (!raid5_dec_bi_active_stripes(bi))
3315                                         bio_list_add(return_bi, bi);
3316                                 bi = nextbi;
3317                         }
3318                 }
3319                 if (bitmap_end)
3320                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3321                                         STRIPE_SECTORS, 0, 0);
3322                 /* If we were in the middle of a write the parity block might
3323                  * still be locked - so just clear all R5_LOCKED flags
3324                  */
3325                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
3326         }
3327         s->to_write = 0;
3328         s->written = 0;
3329
3330         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3331                 if (atomic_dec_and_test(&conf->pending_full_writes))
3332                         md_wakeup_thread(conf->mddev->thread);
3333 }
3334
3335 static void
3336 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
3337                    struct stripe_head_state *s)
3338 {
3339         int abort = 0;
3340         int i;
3341
3342         BUG_ON(sh->batch_head);
3343         clear_bit(STRIPE_SYNCING, &sh->state);
3344         if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3345                 wake_up(&conf->wait_for_overlap);
3346         s->syncing = 0;
3347         s->replacing = 0;
3348         /* There is nothing more to do for sync/check/repair.
3349          * Don't even need to abort as that is handled elsewhere
3350          * if needed, and not always wanted e.g. if there is a known
3351          * bad block here.
3352          * For recover/replace we need to record a bad block on all
3353          * non-sync devices, or abort the recovery
3354          */
3355         if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
3356                 /* During recovery devices cannot be removed, so
3357                  * locking and refcounting of rdevs is not needed
3358                  */
3359                 rcu_read_lock();
3360                 for (i = 0; i < conf->raid_disks; i++) {
3361                         struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
3362                         if (rdev
3363                             && !test_bit(Faulty, &rdev->flags)
3364                             && !test_bit(In_sync, &rdev->flags)
3365                             && !rdev_set_badblocks(rdev, sh->sector,
3366                                                    STRIPE_SECTORS, 0))
3367                                 abort = 1;
3368                         rdev = rcu_dereference(conf->disks[i].replacement);
3369                         if (rdev
3370                             && !test_bit(Faulty, &rdev->flags)
3371                             && !test_bit(In_sync, &rdev->flags)
3372                             && !rdev_set_badblocks(rdev, sh->sector,
3373                                                    STRIPE_SECTORS, 0))
3374                                 abort = 1;
3375                 }
3376                 rcu_read_unlock();
3377                 if (abort)
3378                         conf->recovery_disabled =
3379                                 conf->mddev->recovery_disabled;
3380         }
3381         md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
3382 }
3383
3384 static int want_replace(struct stripe_head *sh, int disk_idx)
3385 {
3386         struct md_rdev *rdev;
3387         int rv = 0;
3388
3389         rcu_read_lock();
3390         rdev = rcu_dereference(sh->raid_conf->disks[disk_idx].replacement);
3391         if (rdev
3392             && !test_bit(Faulty, &rdev->flags)
3393             && !test_bit(In_sync, &rdev->flags)
3394             && (rdev->recovery_offset <= sh->sector
3395                 || rdev->mddev->recovery_cp <= sh->sector))
3396                 rv = 1;
3397         rcu_read_unlock();
3398         return rv;
3399 }
3400
3401 static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
3402                            int disk_idx, int disks)
3403 {
3404         struct r5dev *dev = &sh->dev[disk_idx];
3405         struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
3406                                   &sh->dev[s->failed_num[1]] };
3407         int i;
3408
3409
3410         if (test_bit(R5_LOCKED, &dev->flags) ||
3411             test_bit(R5_UPTODATE, &dev->flags))
3412                 /* No point reading this as we already have it or have
3413                  * decided to get it.
3414                  */
3415                 return 0;
3416
3417         if (dev->toread ||
3418             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
3419                 /* We need this block to directly satisfy a request */
3420                 return 1;
3421
3422         if (s->syncing || s->expanding ||
3423             (s->replacing && want_replace(sh, disk_idx)))
3424                 /* When syncing, or expanding we read everything.
3425                  * When replacing, we need the replaced block.
3426                  */
3427                 return 1;
3428
3429         if ((s->failed >= 1 && fdev[0]->toread) ||
3430             (s->failed >= 2 && fdev[1]->toread))
3431                 /* If we want to read from a failed device, then
3432                  * we need to actually read every other device.
3433                  */
3434                 return 1;
3435
3436         /* Sometimes neither read-modify-write nor reconstruct-write
3437          * cycles can work.  In those cases we read every block we
3438          * can.  Then the parity-update is certain to have enough to
3439          * work with.
3440          * This can only be a problem when we need to write something,
3441          * and some device has failed.  If either of those tests
3442          * fail we need look no further.
3443          */
3444         if (!s->failed || !s->to_write)
3445                 return 0;
3446
3447         if (test_bit(R5_Insync, &dev->flags) &&
3448             !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3449                 /* Pre-reads at not permitted until after short delay
3450                  * to gather multiple requests.  However if this
3451                  * device is no Insync, the block could only be be computed
3452                  * and there is no need to delay that.
3453                  */
3454                 return 0;
3455
3456         for (i = 0; i < s->failed && i < 2; i++) {
3457                 if (fdev[i]->towrite &&
3458                     !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3459                     !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3460                         /* If we have a partial write to a failed
3461                          * device, then we will need to reconstruct
3462                          * the content of that device, so all other
3463                          * devices must be read.
3464                          */
3465                         return 1;
3466         }
3467
3468         /* If we are forced to do a reconstruct-write, either because
3469          * the current RAID6 implementation only supports that, or
3470          * or because parity cannot be trusted and we are currently
3471          * recovering it, there is extra need to be careful.
3472          * If one of the devices that we would need to read, because
3473          * it is not being overwritten (and maybe not written at all)
3474          * is missing/faulty, then we need to read everything we can.
3475          */
3476         if (sh->raid_conf->level != 6 &&
3477             sh->sector < sh->raid_conf->mddev->recovery_cp)
3478                 /* reconstruct-write isn't being forced */
3479                 return 0;
3480         for (i = 0; i < s->failed && i < 2; i++) {
3481                 if (s->failed_num[i] != sh->pd_idx &&
3482                     s->failed_num[i] != sh->qd_idx &&
3483                     !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3484                     !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3485                         return 1;
3486         }
3487
3488         return 0;
3489 }
3490
3491 /* fetch_block - checks the given member device to see if its data needs
3492  * to be read or computed to satisfy a request.
3493  *
3494  * Returns 1 when no more member devices need to be checked, otherwise returns
3495  * 0 to tell the loop in handle_stripe_fill to continue
3496  */
3497 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
3498                        int disk_idx, int disks)
3499 {
3500         struct r5dev *dev = &sh->dev[disk_idx];
3501
3502         /* is the data in this block needed, and can we get it? */
3503         if (need_this_block(sh, s, disk_idx, disks)) {
3504                 /* we would like to get this block, possibly by computing it,
3505                  * otherwise read it if the backing disk is insync
3506                  */
3507                 BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
3508                 BUG_ON(test_bit(R5_Wantread, &dev->flags));
3509                 BUG_ON(sh->batch_head);
3510                 if ((s->uptodate == disks - 1) &&
3511                     (s->failed && (disk_idx == s->failed_num[0] ||
3512                                    disk_idx == s->failed_num[1]))) {
3513                         /* have disk failed, and we're requested to fetch it;
3514                          * do compute it
3515                          */
3516                         pr_debug("Computing stripe %llu block %d\n",
3517                                (unsigned long long)sh->sector, disk_idx);
3518                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3519                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3520                         set_bit(R5_Wantcompute, &dev->flags);
3521                         sh->ops.target = disk_idx;
3522                         sh->ops.target2 = -1; /* no 2nd target */
3523                         s->req_compute = 1;
3524                         /* Careful: from this point on 'uptodate' is in the eye
3525                          * of raid_run_ops which services 'compute' operations
3526                          * before writes. R5_Wantcompute flags a block that will
3527                          * be R5_UPTODATE by the time it is needed for a
3528                          * subsequent operation.
3529                          */
3530                         s->uptodate++;
3531                         return 1;
3532                 } else if (s->uptodate == disks-2 && s->failed >= 2) {
3533                         /* Computing 2-failure is *very* expensive; only
3534                          * do it if failed >= 2
3535                          */
3536                         int other;
3537                         for (other = disks; other--; ) {
3538                                 if (other == disk_idx)
3539                                         continue;
3540                                 if (!test_bit(R5_UPTODATE,
3541                                       &sh->dev[other].flags))
3542                                         break;
3543                         }
3544                         BUG_ON(other < 0);
3545                         pr_debug("Computing stripe %llu blocks %d,%d\n",
3546                                (unsigned long long)sh->sector,
3547                                disk_idx, other);
3548                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3549                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3550                         set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
3551                         set_bit(R5_Wantcompute, &sh->dev[other].flags);
3552                         sh->ops.target = disk_idx;
3553                         sh->ops.target2 = other;
3554                         s->uptodate += 2;
3555                         s->req_compute = 1;
3556                         return 1;
3557                 } else if (test_bit(R5_Insync, &dev->flags)) {
3558                         set_bit(R5_LOCKED, &dev->flags);
3559                         set_bit(R5_Wantread, &dev->flags);
3560                         s->locked++;
3561                         pr_debug("Reading block %d (sync=%d)\n",
3562                                 disk_idx, s->syncing);
3563                 }
3564         }
3565
3566         return 0;
3567 }
3568
3569 /**
3570  * handle_stripe_fill - read or compute data to satisfy pending requests.
3571  */
3572 static void handle_stripe_fill(struct stripe_head *sh,
3573                                struct stripe_head_state *s,
3574                                int disks)
3575 {
3576         int i;
3577
3578         /* look for blocks to read/compute, skip this if a compute
3579          * is already in flight, or if the stripe contents are in the
3580          * midst of changing due to a write
3581          */
3582         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
3583             !sh->reconstruct_state) {
3584
3585                 /*
3586                  * For degraded stripe with data in journal, do not handle
3587                  * read requests yet, instead, flush the stripe to raid
3588                  * disks first, this avoids handling complex rmw of write
3589                  * back cache (prexor with orig_page, and then xor with
3590                  * page) in the read path
3591                  */
3592                 if (s->injournal && s->failed) {
3593                         if (test_bit(STRIPE_R5C_CACHING, &sh->state))
3594                                 r5c_make_stripe_write_out(sh);
3595                         goto out;
3596                 }
3597
3598                 for (i = disks; i--; )
3599                         if (fetch_block(sh, s, i, disks))
3600                                 break;
3601         }
3602 out:
3603         set_bit(STRIPE_HANDLE, &sh->state);
3604 }
3605
3606 static void break_stripe_batch_list(struct stripe_head *head_sh,
3607                                     unsigned long handle_flags);
3608 /* handle_stripe_clean_event
3609  * any written block on an uptodate or failed drive can be returned.
3610  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
3611  * never LOCKED, so we don't need to test 'failed' directly.
3612  */
3613 static void handle_stripe_clean_event(struct r5conf *conf,
3614         struct stripe_head *sh, int disks, struct bio_list *return_bi)
3615 {
3616         int i;
3617         struct r5dev *dev;
3618         int discard_pending = 0;
3619         struct stripe_head *head_sh = sh;
3620         bool do_endio = false;
3621
3622         for (i = disks; i--; )
3623                 if (sh->dev[i].written) {
3624                         dev = &sh->dev[i];
3625                         if (!test_bit(R5_LOCKED, &dev->flags) &&
3626                             (test_bit(R5_UPTODATE, &dev->flags) ||
3627                              test_bit(R5_Discard, &dev->flags) ||
3628                              test_bit(R5_SkipCopy, &dev->flags))) {
3629                                 /* We can return any write requests */
3630                                 struct bio *wbi, *wbi2;
3631                                 pr_debug("Return write for disc %d\n", i);
3632                                 if (test_and_clear_bit(R5_Discard, &dev->flags))
3633                                         clear_bit(R5_UPTODATE, &dev->flags);
3634                                 if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
3635                                         WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
3636                                 }
3637                                 do_endio = true;
3638
3639 returnbi:
3640                                 dev->page = dev->orig_page;
3641                                 wbi = dev->written;
3642                                 dev->written = NULL;
3643                                 while (wbi && wbi->bi_iter.bi_sector <
3644                                         dev->sector + STRIPE_SECTORS) {
3645                                         wbi2 = r5_next_bio(wbi, dev->sector);
3646                                         if (!raid5_dec_bi_active_stripes(wbi)) {
3647                                                 md_write_end(conf->mddev);
3648                                                 bio_list_add(return_bi, wbi);
3649                                         }
3650                                         wbi = wbi2;
3651                                 }
3652                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3653                                                 STRIPE_SECTORS,
3654                                          !test_bit(STRIPE_DEGRADED, &sh->state),
3655                                                 0);
3656                                 if (head_sh->batch_head) {
3657                                         sh = list_first_entry(&sh->batch_list,
3658                                                               struct stripe_head,
3659                                                               batch_list);
3660                                         if (sh != head_sh) {
3661                                                 dev = &sh->dev[i];
3662                                                 goto returnbi;
3663                                         }
3664                                 }
3665                                 sh = head_sh;
3666                                 dev = &sh->dev[i];
3667                         } else if (test_bit(R5_Discard, &dev->flags))
3668                                 discard_pending = 1;
3669                 }
3670
3671         r5l_stripe_write_finished(sh);
3672
3673         if (!discard_pending &&
3674             test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
3675                 int hash;
3676                 clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
3677                 clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3678                 if (sh->qd_idx >= 0) {
3679                         clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
3680                         clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
3681                 }
3682                 /* now that discard is done we can proceed with any sync */
3683                 clear_bit(STRIPE_DISCARD, &sh->state);
3684                 /*
3685                  * SCSI discard will change some bio fields and the stripe has
3686                  * no updated data, so remove it from hash list and the stripe
3687                  * will be reinitialized
3688                  */
3689 unhash:
3690                 hash = sh->hash_lock_index;
3691                 spin_lock_irq(conf->hash_locks + hash);
3692                 remove_hash(sh);
3693                 spin_unlock_irq(conf->hash_locks + hash);
3694                 if (head_sh->batch_head) {
3695                         sh = list_first_entry(&sh->batch_list,
3696                                               struct stripe_head, batch_list);
3697                         if (sh != head_sh)
3698                                         goto unhash;
3699                 }
3700                 sh = head_sh;
3701
3702                 if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
3703                         set_bit(STRIPE_HANDLE, &sh->state);
3704
3705         }
3706
3707         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3708                 if (atomic_dec_and_test(&conf->pending_full_writes))
3709                         md_wakeup_thread(conf->mddev->thread);
3710
3711         if (head_sh->batch_head && do_endio)
3712                 break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
3713 }
3714
3715 /*
3716  * For RMW in write back cache, we need extra page in prexor to store the
3717  * old data. This page is stored in dev->orig_page.
3718  *
3719  * This function checks whether we have data for prexor. The exact logic
3720  * is:
3721  *       R5_UPTODATE && (!R5_InJournal || R5_OrigPageUPTDODATE)
3722  */
3723 static inline bool uptodate_for_rmw(struct r5dev *dev)
3724 {
3725         return (test_bit(R5_UPTODATE, &dev->flags)) &&
3726                 (!test_bit(R5_InJournal, &dev->flags) ||
3727                  test_bit(R5_OrigPageUPTDODATE, &dev->flags));
3728 }
3729
3730 static int handle_stripe_dirtying(struct r5conf *conf,
3731                                   struct stripe_head *sh,
3732                                   struct stripe_head_state *s,
3733                                   int disks)
3734 {
3735         int rmw = 0, rcw = 0, i;
3736         sector_t recovery_cp = conf->mddev->recovery_cp;
3737
3738         /* Check whether resync is now happening or should start.
3739          * If yes, then the array is dirty (after unclean shutdown or
3740          * initial creation), so parity in some stripes might be inconsistent.
3741          * In this case, we need to always do reconstruct-write, to ensure
3742          * that in case of drive failure or read-error correction, we
3743          * generate correct data from the parity.
3744          */
3745         if (conf->rmw_level == PARITY_DISABLE_RMW ||
3746             (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
3747              s->failed == 0)) {
3748                 /* Calculate the real rcw later - for now make it
3749                  * look like rcw is cheaper
3750                  */
3751                 rcw = 1; rmw = 2;
3752                 pr_debug("force RCW rmw_level=%u, recovery_cp=%llu sh->sector=%llu\n",
3753                          conf->rmw_level, (unsigned long long)recovery_cp,
3754                          (unsigned long long)sh->sector);
3755         } else for (i = disks; i--; ) {
3756                 /* would I have to read this buffer for read_modify_write */
3757                 struct r5dev *dev = &sh->dev[i];
3758                 if (((dev->towrite && !delay_towrite(conf, dev, s)) ||
3759                      i == sh->pd_idx || i == sh->qd_idx ||
3760                      test_bit(R5_InJournal, &dev->flags)) &&
3761                     !test_bit(R5_LOCKED, &dev->flags) &&
3762                     !(uptodate_for_rmw(dev) ||
3763                       test_bit(R5_Wantcompute, &dev->flags))) {
3764                         if (test_bit(R5_Insync, &dev->flags))
3765                                 rmw++;
3766                         else
3767                                 rmw += 2*disks;  /* cannot read it */
3768                 }
3769                 /* Would I have to read this buffer for reconstruct_write */
3770                 if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3771                     i != sh->pd_idx && i != sh->qd_idx &&
3772                     !test_bit(R5_LOCKED, &dev->flags) &&
3773                     !(test_bit(R5_UPTODATE, &dev->flags) ||
3774                       test_bit(R5_Wantcompute, &dev->flags))) {
3775                         if (test_bit(R5_Insync, &dev->flags))
3776                                 rcw++;
3777                         else
3778                                 rcw += 2*disks;
3779                 }
3780         }
3781
3782         pr_debug("for sector %llu state 0x%lx, rmw=%d rcw=%d\n",
3783                  (unsigned long long)sh->sector, sh->state, rmw, rcw);
3784         set_bit(STRIPE_HANDLE, &sh->state);
3785         if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_PREFER_RMW)) && rmw > 0) {
3786                 /* prefer read-modify-write, but need to get some data */
3787                 if (conf->mddev->queue)
3788                         blk_add_trace_msg(conf->mddev->queue,
3789                                           "raid5 rmw %llu %d",
3790                                           (unsigned long long)sh->sector, rmw);
3791                 for (i = disks; i--; ) {
3792                         struct r5dev *dev = &sh->dev[i];
3793                         if (test_bit(R5_InJournal, &dev->flags) &&
3794                             dev->page == dev->orig_page &&
3795                             !test_bit(R5_LOCKED, &sh->dev[sh->pd_idx].flags)) {
3796                                 /* alloc page for prexor */
3797                                 struct page *p = alloc_page(GFP_NOIO);
3798
3799                                 if (p) {
3800                                         dev->orig_page = p;
3801                                         continue;
3802                                 }
3803
3804                                 /*
3805                                  * alloc_page() failed, try use
3806                                  * disk_info->extra_page
3807                                  */
3808                                 if (!test_and_set_bit(R5C_EXTRA_PAGE_IN_USE,
3809                                                       &conf->cache_state)) {
3810                                         r5c_use_extra_page(sh);
3811                                         break;
3812                                 }
3813
3814                                 /* extra_page in use, add to delayed_list */
3815                                 set_bit(STRIPE_DELAYED, &sh->state);
3816                                 s->waiting_extra_page = 1;
3817                                 return -EAGAIN;
3818                         }
3819                 }
3820
3821                 for (i = disks; i--; ) {
3822                         struct r5dev *dev = &sh->dev[i];
3823                         if (((dev->towrite && !delay_towrite(conf, dev, s)) ||
3824                              i == sh->pd_idx || i == sh->qd_idx ||
3825                              test_bit(R5_InJournal, &dev->flags)) &&
3826                             !test_bit(R5_LOCKED, &dev->flags) &&
3827                             !(uptodate_for_rmw(dev) ||
3828                               test_bit(R5_Wantcompute, &dev->flags)) &&
3829                             test_bit(R5_Insync, &dev->flags)) {
3830                                 if (test_bit(STRIPE_PREREAD_ACTIVE,
3831                                              &sh->state)) {
3832                                         pr_debug("Read_old block %d for r-m-w\n",
3833                                                  i);
3834                                         set_bit(R5_LOCKED, &dev->flags);
3835                                         set_bit(R5_Wantread, &dev->flags);
3836                                         s->locked++;
3837                                 } else {
3838                                         set_bit(STRIPE_DELAYED, &sh->state);
3839                                         set_bit(STRIPE_HANDLE, &sh->state);
3840                                 }
3841                         }
3842                 }
3843         }
3844         if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_PREFER_RMW)) && rcw > 0) {
3845                 /* want reconstruct write, but need to get some data */
3846                 int qread =0;
3847                 rcw = 0;
3848                 for (i = disks; i--; ) {
3849                         struct r5dev *dev = &sh->dev[i];
3850                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3851                             i != sh->pd_idx && i != sh->qd_idx &&
3852                             !test_bit(R5_LOCKED, &dev->flags) &&
3853                             !(test_bit(R5_UPTODATE, &dev->flags) ||
3854                               test_bit(R5_Wantcompute, &dev->flags))) {
3855                                 rcw++;
3856                                 if (test_bit(R5_Insync, &dev->flags) &&
3857                                     test_bit(STRIPE_PREREAD_ACTIVE,
3858                                              &sh->state)) {
3859                                         pr_debug("Read_old block "
3860                                                 "%d for Reconstruct\n", i);
3861                                         set_bit(R5_LOCKED, &dev->flags);
3862                                         set_bit(R5_Wantread, &dev->flags);
3863                                         s->locked++;
3864                                         qread++;
3865                                 } else {
3866                                         set_bit(STRIPE_DELAYED, &sh->state);
3867                                         set_bit(STRIPE_HANDLE, &sh->state);
3868                                 }
3869                         }
3870                 }
3871                 if (rcw && conf->mddev->queue)
3872                         blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
3873                                           (unsigned long long)sh->sector,
3874                                           rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
3875         }
3876
3877         if (rcw > disks && rmw > disks &&
3878             !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3879                 set_bit(STRIPE_DELAYED, &sh->state);
3880
3881         /* now if nothing is locked, and if we have enough data,
3882          * we can start a write request
3883          */
3884         /* since handle_stripe can be called at any time we need to handle the
3885          * case where a compute block operation has been submitted and then a
3886          * subsequent call wants to start a write request.  raid_run_ops only
3887          * handles the case where compute block and reconstruct are requested
3888          * simultaneously.  If this is not the case then new writes need to be
3889          * held off until the compute completes.
3890          */
3891         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
3892             (s->locked == 0 && (rcw == 0 || rmw == 0) &&
3893              !test_bit(STRIPE_BIT_DELAY, &sh->state)))
3894                 schedule_reconstruction(sh, s, rcw == 0, 0);
3895         return 0;
3896 }
3897
3898 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
3899                                 struct stripe_head_state *s, int disks)
3900 {
3901         struct r5dev *dev = NULL;
3902
3903         BUG_ON(sh->batch_head);
3904         set_bit(STRIPE_HANDLE, &sh->state);
3905
3906         switch (sh->check_state) {
3907         case check_state_idle:
3908                 /* start a new check operation if there are no failures */
3909                 if (s->failed == 0) {
3910                         BUG_ON(s->uptodate != disks);
3911                         sh->check_state = check_state_run;
3912                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
3913                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3914                         s->uptodate--;
3915                         break;
3916                 }
3917                 dev = &sh->dev[s->failed_num[0]];
3918                 /* fall through */
3919         case check_state_compute_result:
3920                 sh->check_state = check_state_idle;
3921                 if (!dev)
3922                         dev = &sh->dev[sh->pd_idx];
3923
3924                 /* check that a write has not made the stripe insync */
3925                 if (test_bit(STRIPE_INSYNC, &sh->state))
3926                         break;
3927
3928                 /* either failed parity check, or recovery is happening */
3929                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
3930                 BUG_ON(s->uptodate != disks);
3931
3932                 set_bit(R5_LOCKED, &dev->flags);
3933                 s->locked++;
3934                 set_bit(R5_Wantwrite, &dev->flags);
3935
3936                 clear_bit(STRIPE_DEGRADED, &sh->state);
3937                 set_bit(STRIPE_INSYNC, &sh->state);
3938                 break;
3939         case check_state_run:
3940                 break; /* we will be called again upon completion */
3941         case check_state_check_result:
3942                 sh->check_state = check_state_idle;
3943
3944                 /* if a failure occurred during the check operation, leave
3945                  * STRIPE_INSYNC not set and let the stripe be handled again
3946                  */
3947                 if (s->failed)
3948                         break;
3949
3950                 /* handle a successful check operation, if parity is correct
3951                  * we are done.  Otherwise update the mismatch count and repair
3952                  * parity if !MD_RECOVERY_CHECK
3953                  */
3954                 if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
3955                         /* parity is correct (on disc,
3956                          * not in buffer any more)
3957                          */
3958                         set_bit(STRIPE_INSYNC, &sh->state);
3959                 else {
3960                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3961                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3962                                 /* don't try to repair!! */
3963                                 set_bit(STRIPE_INSYNC, &sh->state);
3964                         else {
3965                                 sh->check_state = check_state_compute_run;
3966                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3967                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3968                                 set_bit(R5_Wantcompute,
3969                                         &sh->dev[sh->pd_idx].flags);
3970                                 sh->ops.target = sh->pd_idx;
3971                                 sh->ops.target2 = -1;
3972                                 s->uptodate++;
3973                         }
3974                 }
3975                 break;
3976         case check_state_compute_run:
3977                 break;
3978         default:
3979                 pr_err("%s: unknown check_state: %d sector: %llu\n",
3980                        __func__, sh->check_state,
3981                        (unsigned long long) sh->sector);
3982                 BUG();
3983         }
3984 }
3985
3986 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3987                                   struct stripe_head_state *s,
3988                                   int disks)
3989 {
3990         int pd_idx = sh->pd_idx;
3991         int qd_idx = sh->qd_idx;
3992         struct r5dev *dev;
3993
3994         BUG_ON(sh->batch_head);
3995         set_bit(STRIPE_HANDLE, &sh->state);
3996
3997         BUG_ON(s->failed > 2);
3998
3999         /* Want to check and possibly repair P and Q.
4000          * However there could be one 'failed' device, in which
4001          * case we can only check one of them, possibly using the
4002          * other to generate missing data
4003          */
4004
4005         switch (sh->check_state) {
4006         case check_state_idle:
4007                 /* start a new check operation if there are < 2 failures */
4008                 if (s->failed == s->q_failed) {
4009                         /* The only possible failed device holds Q, so it
4010                          * makes sense to check P (If anything else were failed,
4011                          * we would have used P to recreate it).
4012                          */
4013                         sh->check_state = check_state_run;
4014                 }
4015                 if (!s->q_failed && s->failed < 2) {
4016                         /* Q is not failed, and we didn't use it to generate
4017                          * anything, so it makes sense to check it
4018                          */
4019                         if (sh->check_state == check_state_run)
4020                                 sh->check_state = check_state_run_pq;
4021                         else
4022                                 sh->check_state = check_state_run_q;
4023                 }
4024
4025                 /* discard potentially stale zero_sum_result */
4026                 sh->ops.zero_sum_result = 0;
4027
4028                 if (sh->check_state == check_state_run) {
4029                         /* async_xor_zero_sum destroys the contents of P */
4030                         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
4031                         s->uptodate--;
4032                 }
4033                 if (sh->check_state >= check_state_run &&
4034                     sh->check_state <= check_state_run_pq) {
4035                         /* async_syndrome_zero_sum preserves P and Q, so
4036                          * no need to mark them !uptodate here
4037                          */
4038                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
4039                         break;
4040                 }
4041
4042                 /* we have 2-disk failure */
4043                 BUG_ON(s->failed != 2);
4044                 /* fall through */
4045         case check_state_compute_result:
4046                 sh->check_state = check_state_idle;
4047
4048                 /* check that a write has not made the stripe insync */
4049                 if (test_bit(STRIPE_INSYNC, &sh->state))
4050                         break;
4051
4052                 /* now write out any block on a failed drive,
4053                  * or P or Q if they were recomputed
4054                  */
4055                 BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
4056                 if (s->failed == 2) {
4057                         dev = &sh->dev[s->failed_num[1]];
4058                         s->locked++;
4059                         set_bit(R5_LOCKED, &dev->flags);
4060                         set_bit(R5_Wantwrite, &dev->flags);
4061                 }
4062                 if (s->failed >= 1) {
4063                         dev = &sh->dev[s->failed_num[0]];
4064                         s->locked++;
4065                         set_bit(R5_LOCKED, &dev->flags);
4066                         set_bit(R5_Wantwrite, &dev->flags);
4067                 }
4068                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4069                         dev = &sh->dev[pd_idx];
4070                         s->locked++;
4071                         set_bit(R5_LOCKED, &dev->flags);
4072                         set_bit(R5_Wantwrite, &dev->flags);
4073                 }
4074                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4075                         dev = &sh->dev[qd_idx];
4076                         s->locked++;
4077                         set_bit(R5_LOCKED, &dev->flags);
4078                         set_bit(R5_Wantwrite, &dev->flags);
4079                 }
4080                 clear_bit(STRIPE_DEGRADED, &sh->state);
4081
4082                 set_bit(STRIPE_INSYNC, &sh->state);
4083                 break;
4084         case check_state_run:
4085         case check_state_run_q:
4086         case check_state_run_pq:
4087                 break; /* we will be called again upon completion */
4088         case check_state_check_result:
4089                 sh->check_state = check_state_idle;
4090
4091                 /* handle a successful check operation, if parity is correct
4092                  * we are done.  Otherwise update the mismatch count and repair
4093                  * parity if !MD_RECOVERY_CHECK
4094                  */
4095                 if (sh->ops.zero_sum_result == 0) {
4096                         /* both parities are correct */
4097                         if (!s->failed)
4098                                 set_bit(STRIPE_INSYNC, &sh->state);
4099                         else {
4100                                 /* in contrast to the raid5 case we can validate
4101                                  * parity, but still have a failure to write
4102                                  * back
4103                                  */
4104                                 sh->check_state = check_state_compute_result;
4105                                 /* Returning at this point means that we may go
4106                                  * off and bring p and/or q uptodate again so
4107                                  * we make sure to check zero_sum_result again
4108                                  * to verify if p or q need writeback
4109                                  */
4110                         }
4111                 } else {
4112                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
4113                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
4114                                 /* don't try to repair!! */
4115                                 set_bit(STRIPE_INSYNC, &sh->state);
4116                         else {
4117                                 int *target = &sh->ops.target;
4118
4119                                 sh->ops.target = -1;
4120                                 sh->ops.target2 = -1;
4121                                 sh->check_state = check_state_compute_run;
4122                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
4123                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
4124                                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
4125                                         set_bit(R5_Wantcompute,
4126                                                 &sh->dev[pd_idx].flags);
4127                                         *target = pd_idx;
4128                                         target = &sh->ops.target2;
4129                                         s->uptodate++;
4130                                 }
4131                                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
4132                                         set_bit(R5_Wantcompute,
4133                                                 &sh->dev[qd_idx].flags);
4134                                         *target = qd_idx;
4135                                         s->uptodate++;
4136                                 }
4137                         }
4138                 }
4139                 break;
4140         case check_state_compute_run:
4141                 break;
4142         default:
4143                 pr_warn("%s: unknown check_state: %d sector: %llu\n",
4144                         __func__, sh->check_state,
4145                         (unsigned long long) sh->sector);
4146                 BUG();
4147         }
4148 }
4149
4150 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
4151 {
4152         int i;
4153
4154         /* We have read all the blocks in this stripe and now we need to
4155          * copy some of them into a target stripe for expand.
4156          */
4157         struct dma_async_tx_descriptor *tx = NULL;
4158         BUG_ON(sh->batch_head);
4159         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4160         for (i = 0; i < sh->disks; i++)
4161                 if (i != sh->pd_idx && i != sh->qd_idx) {
4162                         int dd_idx, j;
4163                         struct stripe_head *sh2;
4164                         struct async_submit_ctl submit;
4165
4166                         sector_t bn = raid5_compute_blocknr(sh, i, 1);
4167                         sector_t s = raid5_compute_sector(conf, bn, 0,
4168                                                           &dd_idx, NULL);
4169                         sh2 = raid5_get_active_stripe(conf, s, 0, 1, 1);
4170                         if (sh2 == NULL)
4171                                 /* so far only the early blocks of this stripe
4172                                  * have been requested.  When later blocks
4173                                  * get requested, we will try again
4174                                  */
4175                                 continue;
4176                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
4177                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
4178                                 /* must have already done this block */
4179                                 raid5_release_stripe(sh2);
4180                                 continue;
4181                         }
4182
4183                         /* place all the copies on one channel */
4184                         init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
4185                         tx = async_memcpy(sh2->dev[dd_idx].page,
4186                                           sh->dev[i].page, 0, 0, STRIPE_SIZE,
4187                                           &submit);
4188
4189                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
4190                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
4191                         for (j = 0; j < conf->raid_disks; j++)
4192                                 if (j != sh2->pd_idx &&
4193                                     j != sh2->qd_idx &&
4194                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
4195                                         break;
4196                         if (j == conf->raid_disks) {
4197                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
4198                                 set_bit(STRIPE_HANDLE, &sh2->state);
4199                         }
4200                         raid5_release_stripe(sh2);
4201
4202                 }
4203         /* done submitting copies, wait for them to complete */
4204         async_tx_quiesce(&tx);
4205 }
4206
4207 /*
4208  * handle_stripe - do things to a stripe.
4209  *
4210  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
4211  * state of various bits to see what needs to be done.
4212  * Possible results:
4213  *    return some read requests which now have data
4214  *    return some write requests which are safely on storage
4215  *    schedule a read on some buffers
4216  *    schedule a write of some buffers
4217  *    return confirmation of parity correctness
4218  *
4219  */
4220
4221 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
4222 {
4223         struct r5conf *conf = sh->raid_conf;
4224         int disks = sh->disks;
4225         struct r5dev *dev;
4226         int i;
4227         int do_recovery = 0;
4228
4229         memset(s, 0, sizeof(*s));
4230
4231         s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state) && !sh->batch_head;
4232         s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state) && !sh->batch_head;
4233         s->failed_num[0] = -1;
4234         s->failed_num[1] = -1;
4235         s->log_failed = r5l_log_disk_error(conf);
4236
4237         /* Now to look around and see what can be done */
4238         rcu_read_lock();
4239         for (i=disks; i--; ) {
4240                 struct md_rdev *rdev;
4241                 sector_t first_bad;
4242                 int bad_sectors;
4243                 int is_bad = 0;
4244
4245                 dev = &sh->dev[i];
4246
4247                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
4248                          i, dev->flags,
4249                          dev->toread, dev->towrite, dev->written);
4250                 /* maybe we can reply to a read
4251                  *
4252                  * new wantfill requests are only permitted while
4253                  * ops_complete_biofill is guaranteed to be inactive
4254                  */
4255                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
4256                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
4257                         set_bit(R5_Wantfill, &dev->flags);
4258
4259                 /* now count some things */
4260                 if (test_bit(R5_LOCKED, &dev->flags))
4261                         s->locked++;
4262                 if (test_bit(R5_UPTODATE, &dev->flags))
4263                         s->uptodate++;
4264                 if (test_bit(R5_Wantcompute, &dev->flags)) {
4265                         s->compute++;
4266                         BUG_ON(s->compute > 2);
4267                 }
4268
4269                 if (test_bit(R5_Wantfill, &dev->flags))
4270                         s->to_fill++;
4271                 else if (dev->toread)
4272                         s->to_read++;
4273                 if (dev->towrite) {
4274                         s->to_write++;
4275                         if (!test_bit(R5_OVERWRITE, &dev->flags))
4276                                 s->non_overwrite++;
4277                 }
4278                 if (dev->written)
4279                         s->written++;
4280                 /* Prefer to use the replacement for reads, but only
4281                  * if it is recovered enough and has no bad blocks.
4282                  */
4283                 rdev = rcu_dereference(conf->disks[i].replacement);
4284                 if (rdev && !test_bit(Faulty, &rdev->flags) &&
4285                     rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
4286                     !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4287                                  &first_bad, &bad_sectors))
4288                         set_bit(R5_ReadRepl, &dev->flags);
4289                 else {
4290                         if (rdev && !test_bit(Faulty, &rdev->flags))
4291                                 set_bit(R5_NeedReplace, &dev->flags);
4292                         else
4293                                 clear_bit(R5_NeedReplace, &dev->flags);
4294                         rdev = rcu_dereference(conf->disks[i].rdev);
4295                         clear_bit(R5_ReadRepl, &dev->flags);
4296                 }
4297                 if (rdev && test_bit(Faulty, &rdev->flags))
4298                         rdev = NULL;
4299                 if (rdev) {
4300                         is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4301                                              &first_bad, &bad_sectors);
4302                         if (s->blocked_rdev == NULL
4303                             && (test_bit(Blocked, &rdev->flags)
4304                                 || is_bad < 0)) {
4305                                 if (is_bad < 0)
4306                                         set_bit(BlockedBadBlocks,
4307                                                 &rdev->flags);
4308                                 s->blocked_rdev = rdev;
4309                                 atomic_inc(&rdev->nr_pending);
4310                         }
4311                 }
4312                 clear_bit(R5_Insync, &dev->flags);
4313                 if (!rdev)
4314                         /* Not in-sync */;
4315                 else if (is_bad) {
4316                         /* also not in-sync */
4317                         if (!test_bit(WriteErrorSeen, &rdev->flags) &&
4318                             test_bit(R5_UPTODATE, &dev->flags)) {
4319                                 /* treat as in-sync, but with a read error
4320                                  * which we can now try to correct
4321                                  */
4322                                 set_bit(R5_Insync, &dev->flags);
4323                                 set_bit(R5_ReadError, &dev->flags);
4324                         }
4325                 } else if (test_bit(In_sync, &rdev->flags))
4326                         set_bit(R5_Insync, &dev->flags);
4327                 else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
4328                         /* in sync if before recovery_offset */
4329                         set_bit(R5_Insync, &dev->flags);
4330                 else if (test_bit(R5_UPTODATE, &dev->flags) &&
4331                          test_bit(R5_Expanded, &dev->flags))
4332                         /* If we've reshaped into here, we assume it is Insync.
4333                          * We will shortly update recovery_offset to make
4334                          * it official.
4335                          */
4336                         set_bit(R5_Insync, &dev->flags);
4337
4338                 if (test_bit(R5_WriteError, &dev->flags)) {
4339                         /* This flag does not apply to '.replacement'
4340                          * only to .rdev, so make sure to check that*/
4341                         struct md_rdev *rdev2 = rcu_dereference(
4342                                 conf->disks[i].rdev);
4343                         if (rdev2 == rdev)
4344                                 clear_bit(R5_Insync, &dev->flags);
4345                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4346                                 s->handle_bad_blocks = 1;
4347                                 atomic_inc(&rdev2->nr_pending);
4348                         } else
4349                                 clear_bit(R5_WriteError, &dev->flags);
4350                 }
4351                 if (test_bit(R5_MadeGood, &dev->flags)) {
4352                         /* This flag does not apply to '.replacement'
4353                          * only to .rdev, so make sure to check that*/
4354                         struct md_rdev *rdev2 = rcu_dereference(
4355                                 conf->disks[i].rdev);
4356                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4357                                 s->handle_bad_blocks = 1;
4358                                 atomic_inc(&rdev2->nr_pending);
4359                         } else
4360                                 clear_bit(R5_MadeGood, &dev->flags);
4361                 }
4362                 if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
4363                         struct md_rdev *rdev2 = rcu_dereference(
4364                                 conf->disks[i].replacement);
4365                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4366                                 s->handle_bad_blocks = 1;
4367                                 atomic_inc(&rdev2->nr_pending);
4368                         } else
4369                                 clear_bit(R5_MadeGoodRepl, &dev->flags);
4370                 }
4371                 if (!test_bit(R5_Insync, &dev->flags)) {
4372                         /* The ReadError flag will just be confusing now */
4373                         clear_bit(R5_ReadError, &dev->flags);
4374                         clear_bit(R5_ReWrite, &dev->flags);
4375                 }
4376                 if (test_bit(R5_ReadError, &dev->flags))
4377                         clear_bit(R5_Insync, &dev->flags);
4378                 if (!test_bit(R5_Insync, &dev->flags)) {
4379                         if (s->failed < 2)
4380                                 s->failed_num[s->failed] = i;
4381                         s->failed++;
4382                         if (rdev && !test_bit(Faulty, &rdev->flags))
4383                                 do_recovery = 1;
4384                 }
4385
4386                 if (test_bit(R5_InJournal, &dev->flags))
4387                         s->injournal++;
4388                 if (test_bit(R5_InJournal, &dev->flags) && dev->written)
4389                         s->just_cached++;
4390         }
4391         if (test_bit(STRIPE_SYNCING, &sh->state)) {
4392                 /* If there is a failed device being replaced,
4393                  *     we must be recovering.
4394                  * else if we are after recovery_cp, we must be syncing
4395                  * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
4396                  * else we can only be replacing
4397                  * sync and recovery both need to read all devices, and so
4398                  * use the same flag.
4399                  */
4400                 if (do_recovery ||
4401                     sh->sector >= conf->mddev->recovery_cp ||
4402                     test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
4403                         s->syncing = 1;
4404                 else
4405                         s->replacing = 1;
4406         }
4407         rcu_read_unlock();
4408 }
4409
4410 static int clear_batch_ready(struct stripe_head *sh)
4411 {
4412         /* Return '1' if this is a member of batch, or
4413          * '0' if it is a lone stripe or a head which can now be
4414          * handled.
4415          */
4416         struct stripe_head *tmp;
4417         if (!test_and_clear_bit(STRIPE_BATCH_READY, &sh->state))
4418                 return (sh->batch_head && sh->batch_head != sh);
4419         spin_lock(&sh->stripe_lock);
4420         if (!sh->batch_head) {
4421                 spin_unlock(&sh->stripe_lock);
4422                 return 0;
4423         }
4424
4425         /*
4426          * this stripe could be added to a batch list before we check
4427          * BATCH_READY, skips it
4428          */
4429         if (sh->batch_head != sh) {
4430                 spin_unlock(&sh->stripe_lock);
4431                 return 1;
4432         }
4433         spin_lock(&sh->batch_lock);
4434         list_for_each_entry(tmp, &sh->batch_list, batch_list)
4435                 clear_bit(STRIPE_BATCH_READY, &tmp->state);
4436         spin_unlock(&sh->batch_lock);
4437         spin_unlock(&sh->stripe_lock);
4438
4439         /*
4440          * BATCH_READY is cleared, no new stripes can be added.
4441          * batch_list can be accessed without lock
4442          */
4443         return 0;
4444 }
4445
4446 static void break_stripe_batch_list(struct stripe_head *head_sh,
4447                                     unsigned long handle_flags)
4448 {
4449         struct stripe_head *sh, *next;
4450         int i;
4451         int do_wakeup = 0;
4452
4453         list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) {
4454
4455                 list_del_init(&sh->batch_list);
4456
4457                 WARN_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
4458                                           (1 << STRIPE_SYNCING) |
4459                                           (1 << STRIPE_REPLACED) |
4460                                           (1 << STRIPE_DELAYED) |
4461                                           (1 << STRIPE_BIT_DELAY) |
4462                                           (1 << STRIPE_FULL_WRITE) |
4463                                           (1 << STRIPE_BIOFILL_RUN) |
4464                                           (1 << STRIPE_COMPUTE_RUN)  |
4465                                           (1 << STRIPE_OPS_REQ_PENDING) |
4466                                           (1 << STRIPE_DISCARD) |
4467                                           (1 << STRIPE_BATCH_READY) |
4468                                           (1 << STRIPE_BATCH_ERR) |
4469                                           (1 << STRIPE_BITMAP_PENDING)),
4470                         "stripe state: %lx\n", sh->state);
4471                 WARN_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
4472                                               (1 << STRIPE_REPLACED)),
4473                         "head stripe state: %lx\n", head_sh->state);
4474
4475                 set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
4476                                             (1 << STRIPE_PREREAD_ACTIVE) |
4477                                             (1 << STRIPE_DEGRADED)),
4478                               head_sh->state & (1 << STRIPE_INSYNC));
4479
4480                 sh->check_state = head_sh->check_state;
4481                 sh->reconstruct_state = head_sh->reconstruct_state;
4482                 for (i = 0; i < sh->disks; i++) {
4483                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
4484                                 do_wakeup = 1;
4485                         sh->dev[i].flags = head_sh->dev[i].flags &
4486                                 (~((1 << R5_WriteError) | (1 << R5_Overlap)));
4487                 }
4488                 spin_lock_irq(&sh->stripe_lock);
4489                 sh->batch_head = NULL;
4490                 spin_unlock_irq(&sh->stripe_lock);
4491                 if (handle_flags == 0 ||
4492                     sh->state & handle_flags)
4493                         set_bit(STRIPE_HANDLE, &sh->state);
4494                 raid5_release_stripe(sh);
4495         }
4496         spin_lock_irq(&head_sh->stripe_lock);
4497         head_sh->batch_head = NULL;
4498         spin_unlock_irq(&head_sh->stripe_lock);
4499         for (i = 0; i < head_sh->disks; i++)
4500                 if (test_and_clear_bit(R5_Overlap, &head_sh->dev[i].flags))
4501                         do_wakeup = 1;
4502         if (head_sh->state & handle_flags)
4503                 set_bit(STRIPE_HANDLE, &head_sh->state);
4504
4505         if (do_wakeup)
4506                 wake_up(&head_sh->raid_conf->wait_for_overlap);
4507 }
4508
4509 static void handle_stripe(struct stripe_head *sh)
4510 {
4511         struct stripe_head_state s;
4512         struct r5conf *conf = sh->raid_conf;
4513         int i;
4514         int prexor;
4515         int disks = sh->disks;
4516         struct r5dev *pdev, *qdev;
4517
4518         clear_bit(STRIPE_HANDLE, &sh->state);
4519         if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
4520                 /* already being handled, ensure it gets handled
4521                  * again when current action finishes */
4522                 set_bit(STRIPE_HANDLE, &sh->state);
4523                 return;
4524         }
4525
4526         if (clear_batch_ready(sh) ) {
4527                 clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4528                 return;
4529         }
4530
4531         if (test_and_clear_bit(STRIPE_BATCH_ERR, &sh->state))
4532                 break_stripe_batch_list(sh, 0);
4533
4534         if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) && !sh->batch_head) {
4535                 spin_lock(&sh->stripe_lock);
4536                 /* Cannot process 'sync' concurrently with 'discard' */
4537                 if (!test_bit(STRIPE_DISCARD, &sh->state) &&
4538                     test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
4539                         set_bit(STRIPE_SYNCING, &sh->state);
4540                         clear_bit(STRIPE_INSYNC, &sh->state);
4541                         clear_bit(STRIPE_REPLACED, &sh->state);
4542                 }
4543                 spin_unlock(&sh->stripe_lock);
4544         }
4545         clear_bit(STRIPE_DELAYED, &sh->state);
4546
4547         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
4548                 "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
4549                (unsigned long long)sh->sector, sh->state,
4550                atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
4551                sh->check_state, sh->reconstruct_state);
4552
4553         analyse_stripe(sh, &s);
4554
4555         if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
4556                 goto finish;
4557
4558         if (s.handle_bad_blocks) {
4559                 set_bit(STRIPE_HANDLE, &sh->state);
4560                 goto finish;
4561         }
4562
4563         if (unlikely(s.blocked_rdev)) {
4564                 if (s.syncing || s.expanding || s.expanded ||
4565                     s.replacing || s.to_write || s.written) {
4566                         set_bit(STRIPE_HANDLE, &sh->state);
4567                         goto finish;
4568                 }
4569                 /* There is nothing for the blocked_rdev to block */
4570                 rdev_dec_pending(s.blocked_rdev, conf->mddev);
4571                 s.blocked_rdev = NULL;
4572         }
4573
4574         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
4575                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
4576                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
4577         }
4578
4579         pr_debug("locked=%d uptodate=%d to_read=%d"
4580                " to_write=%d failed=%d failed_num=%d,%d\n",
4581                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
4582                s.failed_num[0], s.failed_num[1]);
4583         /* check if the array has lost more than max_degraded devices and,
4584          * if so, some requests might need to be failed.
4585          */
4586         if (s.failed > conf->max_degraded || s.log_failed) {
4587                 sh->check_state = 0;
4588                 sh->reconstruct_state = 0;
4589                 break_stripe_batch_list(sh, 0);
4590                 if (s.to_read+s.to_write+s.written)
4591                         handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
4592                 if (s.syncing + s.replacing)
4593                         handle_failed_sync(conf, sh, &s);
4594         }
4595
4596         /* Now we check to see if any write operations have recently
4597          * completed
4598          */
4599         prexor = 0;
4600         if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
4601                 prexor = 1;
4602         if (sh->reconstruct_state == reconstruct_state_drain_result ||
4603             sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
4604                 sh->reconstruct_state = reconstruct_state_idle;
4605
4606                 /* All the 'written' buffers and the parity block are ready to
4607                  * be written back to disk
4608                  */
4609                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
4610                        !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
4611                 BUG_ON(sh->qd_idx >= 0 &&
4612                        !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
4613                        !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
4614                 for (i = disks; i--; ) {
4615                         struct r5dev *dev = &sh->dev[i];
4616                         if (test_bit(R5_LOCKED, &dev->flags) &&
4617                                 (i == sh->pd_idx || i == sh->qd_idx ||
4618                                  dev->written || test_bit(R5_InJournal,
4619                                                           &dev->flags))) {
4620                                 pr_debug("Writing block %d\n", i);
4621                                 set_bit(R5_Wantwrite, &dev->flags);
4622                                 if (prexor)
4623                                         continue;
4624                                 if (s.failed > 1)
4625                                         continue;
4626                                 if (!test_bit(R5_Insync, &dev->flags) ||
4627                                     ((i == sh->pd_idx || i == sh->qd_idx)  &&
4628                                      s.failed == 0))
4629                                         set_bit(STRIPE_INSYNC, &sh->state);
4630                         }
4631                 }
4632                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4633                         s.dec_preread_active = 1;
4634         }
4635
4636         /*
4637          * might be able to return some write requests if the parity blocks
4638          * are safe, or on a failed drive
4639          */
4640         pdev = &sh->dev[sh->pd_idx];
4641         s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
4642                 || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
4643         qdev = &sh->dev[sh->qd_idx];
4644         s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
4645                 || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
4646                 || conf->level < 6;
4647
4648         if (s.written &&
4649             (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
4650                              && !test_bit(R5_LOCKED, &pdev->flags)
4651                              && (test_bit(R5_UPTODATE, &pdev->flags) ||
4652                                  test_bit(R5_Discard, &pdev->flags))))) &&
4653             (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
4654                              && !test_bit(R5_LOCKED, &qdev->flags)
4655                              && (test_bit(R5_UPTODATE, &qdev->flags) ||
4656                                  test_bit(R5_Discard, &qdev->flags))))))
4657                 handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
4658
4659         if (s.just_cached)
4660                 r5c_handle_cached_data_endio(conf, sh, disks, &s.return_bi);
4661         r5l_stripe_write_finished(sh);
4662
4663         /* Now we might consider reading some blocks, either to check/generate
4664          * parity, or to satisfy requests
4665          * or to load a block that is being partially written.
4666          */
4667         if (s.to_read || s.non_overwrite
4668             || (conf->level == 6 && s.to_write && s.failed)
4669             || (s.syncing && (s.uptodate + s.compute < disks))
4670             || s.replacing
4671             || s.expanding)
4672                 handle_stripe_fill(sh, &s, disks);
4673
4674         /*
4675          * When the stripe finishes full journal write cycle (write to journal
4676          * and raid disk), this is the clean up procedure so it is ready for
4677          * next operation.
4678          */
4679         r5c_finish_stripe_write_out(conf, sh, &s);
4680
4681         /*
4682          * Now to consider new write requests, cache write back and what else,
4683          * if anything should be read.  We do not handle new writes when:
4684          * 1/ A 'write' operation (copy+xor) is already in flight.
4685          * 2/ A 'check' operation is in flight, as it may clobber the parity
4686          *    block.
4687          * 3/ A r5c cache log write is in flight.
4688          */
4689
4690         if (!sh->reconstruct_state && !sh->check_state && !sh->log_io) {
4691                 if (!r5c_is_writeback(conf->log)) {
4692                         if (s.to_write)
4693                                 handle_stripe_dirtying(conf, sh, &s, disks);
4694                 } else { /* write back cache */
4695                         int ret = 0;
4696
4697                         /* First, try handle writes in caching phase */
4698                         if (s.to_write)
4699                                 ret = r5c_try_caching_write(conf, sh, &s,
4700                                                             disks);
4701                         /*
4702                          * If caching phase failed: ret == -EAGAIN
4703                          *    OR
4704                          * stripe under reclaim: !caching && injournal
4705                          *
4706                          * fall back to handle_stripe_dirtying()
4707                          */
4708                         if (ret == -EAGAIN ||
4709                             /* stripe under reclaim: !caching && injournal */
4710                             (!test_bit(STRIPE_R5C_CACHING, &sh->state) &&
4711                              s.injournal > 0)) {
4712                                 ret = handle_stripe_dirtying(conf, sh, &s,
4713                                                              disks);
4714                                 if (ret == -EAGAIN)
4715                                         goto finish;
4716                         }
4717                 }
4718         }
4719
4720         /* maybe we need to check and possibly fix the parity for this stripe
4721          * Any reads will already have been scheduled, so we just see if enough
4722          * data is available.  The parity check is held off while parity
4723          * dependent operations are in flight.
4724          */
4725         if (sh->check_state ||
4726             (s.syncing && s.locked == 0 &&
4727              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4728              !test_bit(STRIPE_INSYNC, &sh->state))) {
4729                 if (conf->level == 6)
4730                         handle_parity_checks6(conf, sh, &s, disks);
4731                 else
4732                         handle_parity_checks5(conf, sh, &s, disks);
4733         }
4734
4735         if ((s.replacing || s.syncing) && s.locked == 0
4736             && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
4737             && !test_bit(STRIPE_REPLACED, &sh->state)) {
4738                 /* Write out to replacement devices where possible */
4739                 for (i = 0; i < conf->raid_disks; i++)
4740                         if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
4741                                 WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
4742                                 set_bit(R5_WantReplace, &sh->dev[i].flags);
4743                                 set_bit(R5_LOCKED, &sh->dev[i].flags);
4744                                 s.locked++;
4745                         }
4746                 if (s.replacing)
4747                         set_bit(STRIPE_INSYNC, &sh->state);
4748                 set_bit(STRIPE_REPLACED, &sh->state);
4749         }
4750         if ((s.syncing || s.replacing) && s.locked == 0 &&
4751             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4752             test_bit(STRIPE_INSYNC, &sh->state)) {
4753                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4754                 clear_bit(STRIPE_SYNCING, &sh->state);
4755                 if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
4756                         wake_up(&conf->wait_for_overlap);
4757         }
4758
4759         /* If the failed drives are just a ReadError, then we might need
4760          * to progress the repair/check process
4761          */
4762         if (s.failed <= conf->max_degraded && !conf->mddev->ro)
4763                 for (i = 0; i < s.failed; i++) {
4764                         struct r5dev *dev = &sh->dev[s.failed_num[i]];
4765                         if (test_bit(R5_ReadError, &dev->flags)
4766                             && !test_bit(R5_LOCKED, &dev->flags)
4767                             && test_bit(R5_UPTODATE, &dev->flags)
4768                                 ) {
4769                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
4770                                         set_bit(R5_Wantwrite, &dev->flags);
4771                                         set_bit(R5_ReWrite, &dev->flags);
4772                                         set_bit(R5_LOCKED, &dev->flags);
4773                                         s.locked++;
4774                                 } else {
4775                                         /* let's read it back */
4776                                         set_bit(R5_Wantread, &dev->flags);
4777                                         set_bit(R5_LOCKED, &dev->flags);
4778                                         s.locked++;
4779                                 }
4780                         }
4781                 }
4782
4783         /* Finish reconstruct operations initiated by the expansion process */
4784         if (sh->reconstruct_state == reconstruct_state_result) {
4785                 struct stripe_head *sh_src
4786                         = raid5_get_active_stripe(conf, sh->sector, 1, 1, 1);
4787                 if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
4788                         /* sh cannot be written until sh_src has been read.
4789                          * so arrange for sh to be delayed a little
4790                          */
4791                         set_bit(STRIPE_DELAYED, &sh->state);
4792                         set_bit(STRIPE_HANDLE, &sh->state);
4793                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
4794                                               &sh_src->state))
4795                                 atomic_inc(&conf->preread_active_stripes);
4796                         raid5_release_stripe(sh_src);
4797                         goto finish;
4798                 }
4799                 if (sh_src)
4800                         raid5_release_stripe(sh_src);
4801
4802                 sh->reconstruct_state = reconstruct_state_idle;
4803                 clear_bit(STRIPE_EXPANDING, &sh->state);
4804                 for (i = conf->raid_disks; i--; ) {
4805                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
4806                         set_bit(R5_LOCKED, &sh->dev[i].flags);
4807                         s.locked++;
4808                 }
4809         }
4810
4811         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
4812             !sh->reconstruct_state) {
4813                 /* Need to write out all blocks after computing parity */
4814                 sh->disks = conf->raid_disks;
4815                 stripe_set_idx(sh->sector, conf, 0, sh);
4816                 schedule_reconstruction(sh, &s, 1, 1);
4817         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
4818                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
4819                 atomic_dec(&conf->reshape_stripes);
4820                 wake_up(&conf->wait_for_overlap);
4821                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4822         }
4823
4824         if (s.expanding && s.locked == 0 &&
4825             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
4826                 handle_stripe_expansion(conf, sh);
4827
4828 finish:
4829         /* wait for this device to become unblocked */
4830         if (unlikely(s.blocked_rdev)) {
4831                 if (conf->mddev->external)
4832                         md_wait_for_blocked_rdev(s.blocked_rdev,
4833                                                  conf->mddev);
4834                 else
4835                         /* Internal metadata will immediately
4836                          * be written by raid5d, so we don't
4837                          * need to wait here.
4838                          */
4839                         rdev_dec_pending(s.blocked_rdev,
4840                                          conf->mddev);
4841         }
4842
4843         if (s.handle_bad_blocks)
4844                 for (i = disks; i--; ) {
4845                         struct md_rdev *rdev;
4846                         struct r5dev *dev = &sh->dev[i];
4847                         if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
4848                                 /* We own a safe reference to the rdev */
4849                                 rdev = conf->disks[i].rdev;
4850                                 if (!rdev_set_badblocks(rdev, sh->sector,
4851                                                         STRIPE_SECTORS, 0))
4852                                         md_error(conf->mddev, rdev);
4853                                 rdev_dec_pending(rdev, conf->mddev);
4854                         }
4855                         if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
4856                                 rdev = conf->disks[i].rdev;
4857                                 rdev_clear_badblocks(rdev, sh->sector,
4858                                                      STRIPE_SECTORS, 0);
4859                                 rdev_dec_pending(rdev, conf->mddev);
4860                         }
4861                         if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
4862                                 rdev = conf->disks[i].replacement;
4863                                 if (!rdev)
4864                                         /* rdev have been moved down */
4865                                         rdev = conf->disks[i].rdev;
4866                                 rdev_clear_badblocks(rdev, sh->sector,
4867                                                      STRIPE_SECTORS, 0);
4868                                 rdev_dec_pending(rdev, conf->mddev);
4869                         }
4870                 }
4871
4872         if (s.ops_request)
4873                 raid_run_ops(sh, s.ops_request);
4874
4875         ops_run_io(sh, &s);
4876
4877         if (s.dec_preread_active) {
4878                 /* We delay this until after ops_run_io so that if make_request
4879                  * is waiting on a flush, it won't continue until the writes
4880                  * have actually been submitted.
4881                  */
4882                 atomic_dec(&conf->preread_active_stripes);
4883                 if (atomic_read(&conf->preread_active_stripes) <
4884                     IO_THRESHOLD)
4885                         md_wakeup_thread(conf->mddev->thread);
4886         }
4887
4888         if (!bio_list_empty(&s.return_bi)) {
4889                 if (test_bit(MD_SB_CHANGE_PENDING, &conf->mddev->sb_flags)) {
4890                         spin_lock_irq(&conf->device_lock);
4891                         bio_list_merge(&conf->return_bi, &s.return_bi);
4892                         spin_unlock_irq(&conf->device_lock);
4893                         md_wakeup_thread(conf->mddev->thread);
4894                 } else
4895                         return_io(&s.return_bi);
4896         }
4897
4898         clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4899 }
4900
4901 static void raid5_activate_delayed(struct r5conf *conf)
4902 {
4903         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
4904                 while (!list_empty(&conf->delayed_list)) {
4905                         struct list_head *l = conf->delayed_list.next;
4906                         struct stripe_head *sh;
4907                         sh = list_entry(l, struct stripe_head, lru);
4908                         list_del_init(l);
4909                         clear_bit(STRIPE_DELAYED, &sh->state);
4910                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4911                                 atomic_inc(&conf->preread_active_stripes);
4912                         list_add_tail(&sh->lru, &conf->hold_list);
4913                         raid5_wakeup_stripe_thread(sh);
4914                 }
4915         }
4916 }
4917
4918 static void activate_bit_delay(struct r5conf *conf,
4919         struct list_head *temp_inactive_list)
4920 {
4921         /* device_lock is held */
4922         struct list_head head;
4923         list_add(&head, &conf->bitmap_list);
4924         list_del_init(&conf->bitmap_list);
4925         while (!list_empty(&head)) {
4926                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
4927                 int hash;
4928                 list_del_init(&sh->lru);
4929                 atomic_inc(&sh->count);
4930                 hash = sh->hash_lock_index;
4931                 __release_stripe(conf, sh, &temp_inactive_list[hash]);
4932         }
4933 }
4934
4935 static int raid5_congested(struct mddev *mddev, int bits)
4936 {
4937         struct r5conf *conf = mddev->private;
4938
4939         /* No difference between reads and writes.  Just check
4940          * how busy the stripe_cache is
4941          */
4942
4943         if (test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
4944                 return 1;
4945
4946         /* Also checks whether there is pressure on r5cache log space */
4947         if (test_bit(R5C_LOG_TIGHT, &conf->cache_state))
4948                 return 1;
4949         if (conf->quiesce)
4950                 return 1;
4951         if (atomic_read(&conf->empty_inactive_list_nr))
4952                 return 1;
4953
4954         return 0;
4955 }
4956
4957 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
4958 {
4959         struct r5conf *conf = mddev->private;
4960         sector_t sector = bio->bi_iter.bi_sector + get_start_sect(bio->bi_bdev);
4961         unsigned int chunk_sectors;
4962         unsigned int bio_sectors = bio_sectors(bio);
4963
4964         chunk_sectors = min(conf->chunk_sectors, conf->prev_chunk_sectors);
4965         return  chunk_sectors >=
4966                 ((sector & (chunk_sectors - 1)) + bio_sectors);
4967 }
4968
4969 /*
4970  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
4971  *  later sampled by raid5d.
4972  */
4973 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
4974 {
4975         unsigned long flags;
4976
4977         spin_lock_irqsave(&conf->device_lock, flags);
4978
4979         bi->bi_next = conf->retry_read_aligned_list;
4980         conf->retry_read_aligned_list = bi;
4981
4982         spin_unlock_irqrestore(&conf->device_lock, flags);
4983         md_wakeup_thread(conf->mddev->thread);
4984 }
4985
4986 static struct bio *remove_bio_from_retry(struct r5conf *conf)
4987 {
4988         struct bio *bi;
4989
4990         bi = conf->retry_read_aligned;
4991         if (bi) {
4992                 conf->retry_read_aligned = NULL;
4993                 return bi;
4994         }
4995         bi = conf->retry_read_aligned_list;
4996         if(bi) {
4997                 conf->retry_read_aligned_list = bi->bi_next;
4998                 bi->bi_next = NULL;
4999                 /*
5000                  * this sets the active strip count to 1 and the processed
5001                  * strip count to zero (upper 8 bits)
5002                  */
5003                 raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
5004         }
5005
5006         return bi;
5007 }
5008
5009 /*
5010  *  The "raid5_align_endio" should check if the read succeeded and if it
5011  *  did, call bio_endio on the original bio (having bio_put the new bio
5012  *  first).
5013  *  If the read failed..
5014  */
5015 static void raid5_align_endio(struct bio *bi)
5016 {
5017         struct bio* raid_bi  = bi->bi_private;
5018         struct mddev *mddev;
5019         struct r5conf *conf;
5020         struct md_rdev *rdev;
5021         int error = bi->bi_error;
5022
5023         bio_put(bi);
5024
5025         rdev = (void*)raid_bi->bi_next;
5026         raid_bi->bi_next = NULL;
5027         mddev = rdev->mddev;
5028         conf = mddev->private;
5029
5030         rdev_dec_pending(rdev, conf->mddev);
5031
5032         if (!error) {
5033                 trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
5034                                          raid_bi, 0);
5035                 bio_endio(raid_bi);
5036                 if (atomic_dec_and_test(&conf->active_aligned_reads))
5037                         wake_up(&conf->wait_for_quiescent);
5038                 return;
5039         }
5040
5041         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
5042
5043         add_bio_to_retry(raid_bi, conf);
5044 }
5045
5046 static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
5047 {
5048         struct r5conf *conf = mddev->private;
5049         int dd_idx;
5050         struct bio* align_bi;
5051         struct md_rdev *rdev;
5052         sector_t end_sector;
5053
5054         if (!in_chunk_boundary(mddev, raid_bio)) {
5055                 pr_debug("%s: non aligned\n", __func__);
5056                 return 0;
5057         }
5058         /*
5059          * use bio_clone_fast to make a copy of the bio
5060          */
5061         align_bi = bio_clone_fast(raid_bio, GFP_NOIO, mddev->bio_set);
5062         if (!align_bi)
5063                 return 0;
5064         /*
5065          *   set bi_end_io to a new function, and set bi_private to the
5066          *     original bio.
5067          */
5068         align_bi->bi_end_io  = raid5_align_endio;
5069         align_bi->bi_private = raid_bio;
5070         /*
5071          *      compute position
5072          */
5073         align_bi->bi_iter.bi_sector =
5074                 raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector,
5075                                      0, &dd_idx, NULL);
5076
5077         end_sector = bio_end_sector(align_bi);
5078         rcu_read_lock();
5079         rdev = rcu_dereference(conf->disks[dd_idx].replacement);
5080         if (!rdev || test_bit(Faulty, &rdev->flags) ||
5081             rdev->recovery_offset < end_sector) {
5082                 rdev = rcu_dereference(conf->disks[dd_idx].rdev);
5083                 if (rdev &&
5084                     (test_bit(Faulty, &rdev->flags) ||
5085                     !(test_bit(In_sync, &rdev->flags) ||
5086                       rdev->recovery_offset >= end_sector)))
5087                         rdev = NULL;
5088         }
5089
5090         if (r5c_big_stripe_cached(conf, align_bi->bi_iter.bi_sector)) {
5091                 rcu_read_unlock();
5092                 bio_put(align_bi);
5093                 return 0;
5094         }
5095
5096         if (rdev) {
5097                 sector_t first_bad;
5098                 int bad_sectors;
5099
5100                 atomic_inc(&rdev->nr_pending);
5101                 rcu_read_unlock();
5102                 raid_bio->bi_next = (void*)rdev;
5103                 align_bi->bi_bdev =  rdev->bdev;
5104                 bio_clear_flag(align_bi, BIO_SEG_VALID);
5105
5106                 if (is_badblock(rdev, align_bi->bi_iter.bi_sector,
5107                                 bio_sectors(align_bi),
5108                                 &first_bad, &bad_sectors)) {
5109                         bio_put(align_bi);
5110                         rdev_dec_pending(rdev, mddev);
5111                         return 0;
5112                 }
5113
5114                 /* No reshape active, so we can trust rdev->data_offset */
5115                 align_bi->bi_iter.bi_sector += rdev->data_offset;
5116
5117                 spin_lock_irq(&conf->device_lock);
5118                 wait_event_lock_irq(conf->wait_for_quiescent,
5119                                     conf->quiesce == 0,
5120                                     conf->device_lock);
5121                 atomic_inc(&conf->active_aligned_reads);
5122                 spin_unlock_irq(&conf->device_lock);
5123
5124                 if (mddev->gendisk)
5125                         trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
5126                                               align_bi, disk_devt(mddev->gendisk),
5127                                               raid_bio->bi_iter.bi_sector);
5128                 generic_make_request(align_bi);
5129                 return 1;
5130         } else {
5131                 rcu_read_unlock();
5132                 bio_put(align_bi);
5133                 return 0;
5134         }
5135 }
5136
5137 static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
5138 {
5139         struct bio *split;
5140
5141         do {
5142                 sector_t sector = raid_bio->bi_iter.bi_sector;
5143                 unsigned chunk_sects = mddev->chunk_sectors;
5144                 unsigned sectors = chunk_sects - (sector & (chunk_sects-1));
5145
5146                 if (sectors < bio_sectors(raid_bio)) {
5147                         split = bio_split(raid_bio, sectors, GFP_NOIO, fs_bio_set);
5148                         bio_chain(split, raid_bio);
5149                 } else
5150                         split = raid_bio;
5151
5152                 if (!raid5_read_one_chunk(mddev, split)) {
5153                         if (split != raid_bio)
5154                                 generic_make_request(raid_bio);
5155                         return split;
5156                 }
5157         } while (split != raid_bio);
5158
5159         return NULL;
5160 }
5161
5162 /* __get_priority_stripe - get the next stripe to process
5163  *
5164  * Full stripe writes are allowed to pass preread active stripes up until
5165  * the bypass_threshold is exceeded.  In general the bypass_count
5166  * increments when the handle_list is handled before the hold_list; however, it
5167  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
5168  * stripe with in flight i/o.  The bypass_count will be reset when the
5169  * head of the hold_list has changed, i.e. the head was promoted to the
5170  * handle_list.
5171  */
5172 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
5173 {
5174         struct stripe_head *sh = NULL, *tmp;
5175         struct list_head *handle_list = NULL;
5176         struct r5worker_group *wg = NULL;
5177
5178         if (conf->worker_cnt_per_group == 0) {
5179                 handle_list = &conf->handle_list;
5180         } else if (group != ANY_GROUP) {
5181                 handle_list = &conf->worker_groups[group].handle_list;
5182                 wg = &conf->worker_groups[group];
5183         } else {
5184                 int i;
5185                 for (i = 0; i < conf->group_cnt; i++) {
5186                         handle_list = &conf->worker_groups[i].handle_list;
5187                         wg = &conf->worker_groups[i];
5188                         if (!list_empty(handle_list))
5189                                 break;
5190                 }
5191         }
5192
5193         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
5194                   __func__,
5195                   list_empty(handle_list) ? "empty" : "busy",
5196                   list_empty(&conf->hold_list) ? "empty" : "busy",
5197                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
5198
5199         if (!list_empty(handle_list)) {
5200                 sh = list_entry(handle_list->next, typeof(*sh), lru);
5201
5202                 if (list_empty(&conf->hold_list))
5203                         conf->bypass_count = 0;
5204                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
5205                         if (conf->hold_list.next == conf->last_hold)
5206                                 conf->bypass_count++;
5207                         else {
5208                                 conf->last_hold = conf->hold_list.next;
5209                                 conf->bypass_count -= conf->bypass_threshold;
5210                                 if (conf->bypass_count < 0)
5211                                         conf->bypass_count = 0;
5212                         }
5213                 }
5214         } else if (!list_empty(&conf->hold_list) &&
5215                    ((conf->bypass_threshold &&
5216                      conf->bypass_count > conf->bypass_threshold) ||
5217                     atomic_read(&conf->pending_full_writes) == 0)) {
5218
5219                 list_for_each_entry(tmp, &conf->hold_list,  lru) {
5220                         if (conf->worker_cnt_per_group == 0 ||
5221                             group == ANY_GROUP ||
5222                             !cpu_online(tmp->cpu) ||
5223                             cpu_to_group(tmp->cpu) == group) {
5224                                 sh = tmp;
5225                                 break;
5226                         }
5227                 }
5228
5229                 if (sh) {
5230                         conf->bypass_count -= conf->bypass_threshold;
5231                         if (conf->bypass_count < 0)
5232                                 conf->bypass_count = 0;
5233                 }
5234                 wg = NULL;
5235         }
5236
5237         if (!sh)
5238                 return NULL;
5239
5240         if (wg) {
5241                 wg->stripes_cnt--;
5242                 sh->group = NULL;
5243         }
5244         list_del_init(&sh->lru);
5245         BUG_ON(atomic_inc_return(&sh->count) != 1);
5246         return sh;
5247 }
5248
5249 struct raid5_plug_cb {
5250         struct blk_plug_cb      cb;
5251         struct list_head        list;
5252         struct list_head        temp_inactive_list[NR_STRIPE_HASH_LOCKS];
5253 };
5254
5255 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
5256 {
5257         struct raid5_plug_cb *cb = container_of(
5258                 blk_cb, struct raid5_plug_cb, cb);
5259         struct stripe_head *sh;
5260         struct mddev *mddev = cb->cb.data;
5261         struct r5conf *conf = mddev->private;
5262         int cnt = 0;
5263         int hash;
5264
5265         if (cb->list.next && !list_empty(&cb->list)) {
5266                 spin_lock_irq(&conf->device_lock);
5267                 while (!list_empty(&cb->list)) {
5268                         sh = list_first_entry(&cb->list, struct stripe_head, lru);
5269                         list_del_init(&sh->lru);
5270                         /*
5271                          * avoid race release_stripe_plug() sees
5272                          * STRIPE_ON_UNPLUG_LIST clear but the stripe
5273                          * is still in our list
5274                          */
5275                         smp_mb__before_atomic();
5276                         clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
5277                         /*
5278                          * STRIPE_ON_RELEASE_LIST could be set here. In that
5279                          * case, the count is always > 1 here
5280                          */
5281                         hash = sh->hash_lock_index;
5282                         __release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
5283                         cnt++;
5284                 }
5285                 spin_unlock_irq(&conf->device_lock);
5286         }
5287         release_inactive_stripe_list(conf, cb->temp_inactive_list,
5288                                      NR_STRIPE_HASH_LOCKS);
5289         if (mddev->queue)
5290                 trace_block_unplug(mddev->queue, cnt, !from_schedule);
5291         kfree(cb);
5292 }
5293
5294 static void release_stripe_plug(struct mddev *mddev,
5295                                 struct stripe_head *sh)
5296 {
5297         struct blk_plug_cb *blk_cb = blk_check_plugged(
5298                 raid5_unplug, mddev,
5299                 sizeof(struct raid5_plug_cb));
5300         struct raid5_plug_cb *cb;
5301
5302         if (!blk_cb) {
5303                 raid5_release_stripe(sh);
5304                 return;
5305         }
5306
5307         cb = container_of(blk_cb, struct raid5_plug_cb, cb);
5308
5309         if (cb->list.next == NULL) {
5310                 int i;
5311                 INIT_LIST_HEAD(&cb->list);
5312                 for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5313                         INIT_LIST_HEAD(cb->temp_inactive_list + i);
5314         }
5315
5316         if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
5317                 list_add_tail(&sh->lru, &cb->list);
5318         else
5319                 raid5_release_stripe(sh);
5320 }
5321
5322 static void make_discard_request(struct mddev *mddev, struct bio *bi)
5323 {
5324         struct r5conf *conf = mddev->private;
5325         sector_t logical_sector, last_sector;
5326         struct stripe_head *sh;
5327         int remaining;
5328         int stripe_sectors;
5329
5330         if (mddev->reshape_position != MaxSector)
5331                 /* Skip discard while reshape is happening */
5332                 return;
5333
5334         logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5335         last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9);
5336
5337         bi->bi_next = NULL;
5338         bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
5339
5340         stripe_sectors = conf->chunk_sectors *
5341                 (conf->raid_disks - conf->max_degraded);
5342         logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
5343                                                stripe_sectors);
5344         sector_div(last_sector, stripe_sectors);
5345
5346         logical_sector *= conf->chunk_sectors;
5347         last_sector *= conf->chunk_sectors;
5348
5349         for (; logical_sector < last_sector;
5350              logical_sector += STRIPE_SECTORS) {
5351                 DEFINE_WAIT(w);
5352                 int d;
5353         again:
5354                 sh = raid5_get_active_stripe(conf, logical_sector, 0, 0, 0);
5355                 prepare_to_wait(&conf->wait_for_overlap, &w,
5356                                 TASK_UNINTERRUPTIBLE);
5357                 set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5358                 if (test_bit(STRIPE_SYNCING, &sh->state)) {
5359                         raid5_release_stripe(sh);
5360                         schedule();
5361                         goto again;
5362                 }
5363                 clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5364                 spin_lock_irq(&sh->stripe_lock);
5365                 for (d = 0; d < conf->raid_disks; d++) {
5366                         if (d == sh->pd_idx || d == sh->qd_idx)
5367                                 continue;
5368                         if (sh->dev[d].towrite || sh->dev[d].toread) {
5369                                 set_bit(R5_Overlap, &sh->dev[d].flags);
5370                                 spin_unlock_irq(&sh->stripe_lock);
5371                                 raid5_release_stripe(sh);
5372                                 schedule();
5373                                 goto again;
5374                         }
5375                 }
5376                 set_bit(STRIPE_DISCARD, &sh->state);
5377                 finish_wait(&conf->wait_for_overlap, &w);
5378                 sh->overwrite_disks = 0;
5379                 for (d = 0; d < conf->raid_disks; d++) {
5380                         if (d == sh->pd_idx || d == sh->qd_idx)
5381                                 continue;
5382                         sh->dev[d].towrite = bi;
5383                         set_bit(R5_OVERWRITE, &sh->dev[d].flags);
5384                         raid5_inc_bi_active_stripes(bi);
5385                         sh->overwrite_disks++;
5386                 }
5387                 spin_unlock_irq(&sh->stripe_lock);
5388                 if (conf->mddev->bitmap) {
5389                         for (d = 0;
5390                              d < conf->raid_disks - conf->max_degraded;
5391                              d++)
5392                                 bitmap_startwrite(mddev->bitmap,
5393                                                   sh->sector,
5394                                                   STRIPE_SECTORS,
5395                                                   0);
5396                         sh->bm_seq = conf->seq_flush + 1;
5397                         set_bit(STRIPE_BIT_DELAY, &sh->state);
5398                 }
5399
5400                 set_bit(STRIPE_HANDLE, &sh->state);
5401                 clear_bit(STRIPE_DELAYED, &sh->state);
5402                 if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5403                         atomic_inc(&conf->preread_active_stripes);
5404                 release_stripe_plug(mddev, sh);
5405         }
5406
5407         remaining = raid5_dec_bi_active_stripes(bi);
5408         if (remaining == 0) {
5409                 md_write_end(mddev);
5410                 bio_endio(bi);
5411         }
5412 }
5413
5414 static void raid5_make_request(struct mddev *mddev, struct bio * bi)
5415 {
5416         struct r5conf *conf = mddev->private;
5417         int dd_idx;
5418         sector_t new_sector;
5419         sector_t logical_sector, last_sector;
5420         struct stripe_head *sh;
5421         const int rw = bio_data_dir(bi);
5422         int remaining;
5423         DEFINE_WAIT(w);
5424         bool do_prepare;
5425         bool do_flush = false;
5426
5427         if (unlikely(bi->bi_opf & REQ_PREFLUSH)) {
5428                 int ret = r5l_handle_flush_request(conf->log, bi);
5429
5430                 if (ret == 0)
5431                         return;
5432                 if (ret == -ENODEV) {
5433                         md_flush_request(mddev, bi);
5434                         return;
5435                 }
5436                 /* ret == -EAGAIN, fallback */
5437                 /*
5438                  * if r5l_handle_flush_request() didn't clear REQ_PREFLUSH,
5439                  * we need to flush journal device
5440                  */
5441                 do_flush = bi->bi_opf & REQ_PREFLUSH;
5442         }
5443
5444         md_write_start(mddev, bi);
5445
5446         /*
5447          * If array is degraded, better not do chunk aligned read because
5448          * later we might have to read it again in order to reconstruct
5449          * data on failed drives.
5450          */
5451         if (rw == READ && mddev->degraded == 0 &&
5452             mddev->reshape_position == MaxSector) {
5453                 bi = chunk_aligned_read(mddev, bi);
5454                 if (!bi)
5455                         return;
5456         }
5457
5458         if (unlikely(bio_op(bi) == REQ_OP_DISCARD)) {
5459                 make_discard_request(mddev, bi);
5460                 return;
5461         }
5462
5463         logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5464         last_sector = bio_end_sector(bi);
5465         bi->bi_next = NULL;
5466         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
5467
5468         prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
5469         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
5470                 int previous;
5471                 int seq;
5472
5473                 do_prepare = false;
5474         retry:
5475                 seq = read_seqcount_begin(&conf->gen_lock);
5476                 previous = 0;
5477                 if (do_prepare)
5478                         prepare_to_wait(&conf->wait_for_overlap, &w,
5479                                 TASK_UNINTERRUPTIBLE);
5480                 if (unlikely(conf->reshape_progress != MaxSector)) {
5481                         /* spinlock is needed as reshape_progress may be
5482                          * 64bit on a 32bit platform, and so it might be
5483                          * possible to see a half-updated value
5484                          * Of course reshape_progress could change after
5485                          * the lock is dropped, so once we get a reference
5486                          * to the stripe that we think it is, we will have
5487                          * to check again.
5488                          */
5489                         spin_lock_irq(&conf->device_lock);
5490                         if (mddev->reshape_backwards
5491                             ? logical_sector < conf->reshape_progress
5492                             : logical_sector >= conf->reshape_progress) {
5493                                 previous = 1;
5494                         } else {
5495                                 if (mddev->reshape_backwards
5496                                     ? logical_sector < conf->reshape_safe
5497                                     : logical_sector >= conf->reshape_safe) {
5498                                         spin_unlock_irq(&conf->device_lock);
5499                                         schedule();
5500                                         do_prepare = true;
5501                                         goto retry;
5502                                 }
5503                         }
5504                         spin_unlock_irq(&conf->device_lock);
5505                 }
5506
5507                 new_sector = raid5_compute_sector(conf, logical_sector,
5508                                                   previous,
5509                                                   &dd_idx, NULL);
5510                 pr_debug("raid456: raid5_make_request, sector %llu logical %llu\n",
5511                         (unsigned long long)new_sector,
5512                         (unsigned long long)logical_sector);
5513
5514                 sh = raid5_get_active_stripe(conf, new_sector, previous,
5515                                        (bi->bi_opf & REQ_RAHEAD), 0);
5516                 if (sh) {
5517                         if (unlikely(previous)) {
5518                                 /* expansion might have moved on while waiting for a
5519                                  * stripe, so we must do the range check again.
5520                                  * Expansion could still move past after this
5521                                  * test, but as we are holding a reference to
5522                                  * 'sh', we know that if that happens,
5523                                  *  STRIPE_EXPANDING will get set and the expansion
5524                                  * won't proceed until we finish with the stripe.
5525                                  */
5526                                 int must_retry = 0;
5527                                 spin_lock_irq(&conf->device_lock);
5528                                 if (mddev->reshape_backwards
5529                                     ? logical_sector >= conf->reshape_progress
5530                                     : logical_sector < conf->reshape_progress)
5531                                         /* mismatch, need to try again */
5532                                         must_retry = 1;
5533                                 spin_unlock_irq(&conf->device_lock);
5534                                 if (must_retry) {
5535                                         raid5_release_stripe(sh);
5536                                         schedule();
5537                                         do_prepare = true;
5538                                         goto retry;
5539                                 }
5540                         }
5541                         if (read_seqcount_retry(&conf->gen_lock, seq)) {
5542                                 /* Might have got the wrong stripe_head
5543                                  * by accident
5544                                  */
5545                                 raid5_release_stripe(sh);
5546                                 goto retry;
5547                         }
5548
5549                         if (rw == WRITE &&
5550                             logical_sector >= mddev->suspend_lo &&
5551                             logical_sector < mddev->suspend_hi) {
5552                                 raid5_release_stripe(sh);
5553                                 /* As the suspend_* range is controlled by
5554                                  * userspace, we want an interruptible
5555                                  * wait.
5556                                  */
5557                                 flush_signals(current);
5558                                 prepare_to_wait(&conf->wait_for_overlap,
5559                                                 &w, TASK_INTERRUPTIBLE);
5560                                 if (logical_sector >= mddev->suspend_lo &&
5561                                     logical_sector < mddev->suspend_hi) {
5562                                         schedule();
5563                                         do_prepare = true;
5564                                 }
5565                                 goto retry;
5566                         }
5567
5568                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
5569                             !add_stripe_bio(sh, bi, dd_idx, rw, previous)) {
5570                                 /* Stripe is busy expanding or
5571                                  * add failed due to overlap.  Flush everything
5572                                  * and wait a while
5573                                  */
5574                                 md_wakeup_thread(mddev->thread);
5575                                 raid5_release_stripe(sh);
5576                                 schedule();
5577                                 do_prepare = true;
5578                                 goto retry;
5579                         }
5580                         if (do_flush) {
5581                                 set_bit(STRIPE_R5C_PREFLUSH, &sh->state);
5582                                 /* we only need flush for one stripe */
5583                                 do_flush = false;
5584                         }
5585
5586                         set_bit(STRIPE_HANDLE, &sh->state);
5587                         clear_bit(STRIPE_DELAYED, &sh->state);
5588                         if ((!sh->batch_head || sh == sh->batch_head) &&
5589                             (bi->bi_opf & REQ_SYNC) &&
5590                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5591                                 atomic_inc(&conf->preread_active_stripes);
5592                         release_stripe_plug(mddev, sh);
5593                 } else {
5594                         /* cannot get stripe for read-ahead, just give-up */
5595                         bi->bi_error = -EIO;
5596                         break;
5597                 }
5598         }
5599         finish_wait(&conf->wait_for_overlap, &w);
5600
5601         remaining = raid5_dec_bi_active_stripes(bi);
5602         if (remaining == 0) {
5603
5604                 if ( rw == WRITE )
5605                         md_write_end(mddev);
5606
5607                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
5608                                          bi, 0);
5609                 bio_endio(bi);
5610         }
5611 }
5612
5613 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
5614
5615 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
5616 {
5617         /* reshaping is quite different to recovery/resync so it is
5618          * handled quite separately ... here.
5619          *
5620          * On each call to sync_request, we gather one chunk worth of
5621          * destination stripes and flag them as expanding.
5622          * Then we find all the source stripes and request reads.
5623          * As the reads complete, handle_stripe will copy the data
5624          * into the destination stripe and release that stripe.
5625          */
5626         struct r5conf *conf = mddev->private;
5627         struct stripe_head *sh;
5628         sector_t first_sector, last_sector;
5629         int raid_disks = conf->previous_raid_disks;
5630         int data_disks = raid_disks - conf->max_degraded;
5631         int new_data_disks = conf->raid_disks - conf->max_degraded;
5632         int i;
5633         int dd_idx;
5634         sector_t writepos, readpos, safepos;
5635         sector_t stripe_addr;
5636         int reshape_sectors;
5637         struct list_head stripes;
5638         sector_t retn;
5639
5640         if (sector_nr == 0) {
5641                 /* If restarting in the middle, skip the initial sectors */
5642                 if (mddev->reshape_backwards &&
5643                     conf->reshape_progress < raid5_size(mddev, 0, 0)) {
5644                         sector_nr = raid5_size(mddev, 0, 0)
5645                                 - conf->reshape_progress;
5646                 } else if (mddev->reshape_backwards &&
5647                            conf->reshape_progress == MaxSector) {
5648                         /* shouldn't happen, but just in case, finish up.*/
5649                         sector_nr = MaxSector;
5650                 } else if (!mddev->reshape_backwards &&
5651                            conf->reshape_progress > 0)
5652                         sector_nr = conf->reshape_progress;
5653                 sector_div(sector_nr, new_data_disks);
5654                 if (sector_nr) {
5655                         mddev->curr_resync_completed = sector_nr;
5656                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5657                         *skipped = 1;
5658                         retn = sector_nr;
5659                         goto finish;
5660                 }
5661         }
5662
5663         /* We need to process a full chunk at a time.
5664          * If old and new chunk sizes differ, we need to process the
5665          * largest of these
5666          */
5667
5668         reshape_sectors = max(conf->chunk_sectors, conf->prev_chunk_sectors);
5669
5670         /* We update the metadata at least every 10 seconds, or when
5671          * the data about to be copied would over-write the source of
5672          * the data at the front of the range.  i.e. one new_stripe
5673          * along from reshape_progress new_maps to after where
5674          * reshape_safe old_maps to
5675          */
5676         writepos = conf->reshape_progress;
5677         sector_div(writepos, new_data_disks);
5678         readpos = conf->reshape_progress;
5679         sector_div(readpos, data_disks);
5680         safepos = conf->reshape_safe;
5681         sector_div(safepos, data_disks);
5682         if (mddev->reshape_backwards) {
5683                 BUG_ON(writepos < reshape_sectors);
5684                 writepos -= reshape_sectors;
5685                 readpos += reshape_sectors;
5686                 safepos += reshape_sectors;
5687         } else {
5688                 writepos += reshape_sectors;
5689                 /* readpos and safepos are worst-case calculations.
5690                  * A negative number is overly pessimistic, and causes
5691                  * obvious problems for unsigned storage.  So clip to 0.
5692                  */
5693                 readpos -= min_t(sector_t, reshape_sectors, readpos);
5694                 safepos -= min_t(sector_t, reshape_sectors, safepos);
5695         }
5696
5697         /* Having calculated the 'writepos' possibly use it
5698          * to set 'stripe_addr' which is where we will write to.
5699          */
5700         if (mddev->reshape_backwards) {
5701                 BUG_ON(conf->reshape_progress == 0);
5702                 stripe_addr = writepos;
5703                 BUG_ON((mddev->dev_sectors &
5704                         ~((sector_t)reshape_sectors - 1))
5705                        - reshape_sectors - stripe_addr
5706                        != sector_nr);
5707         } else {
5708                 BUG_ON(writepos != sector_nr + reshape_sectors);
5709                 stripe_addr = sector_nr;
5710         }
5711
5712         /* 'writepos' is the most advanced device address we might write.
5713          * 'readpos' is the least advanced device address we might read.
5714          * 'safepos' is the least address recorded in the metadata as having
5715          *     been reshaped.
5716          * If there is a min_offset_diff, these are adjusted either by
5717          * increasing the safepos/readpos if diff is negative, or
5718          * increasing writepos if diff is positive.
5719          * If 'readpos' is then behind 'writepos', there is no way that we can
5720          * ensure safety in the face of a crash - that must be done by userspace
5721          * making a backup of the data.  So in that case there is no particular
5722          * rush to update metadata.
5723          * Otherwise if 'safepos' is behind 'writepos', then we really need to
5724          * update the metadata to advance 'safepos' to match 'readpos' so that
5725          * we can be safe in the event of a crash.
5726          * So we insist on updating metadata if safepos is behind writepos and
5727          * readpos is beyond writepos.
5728          * In any case, update the metadata every 10 seconds.
5729          * Maybe that number should be configurable, but I'm not sure it is
5730          * worth it.... maybe it could be a multiple of safemode_delay???
5731          */
5732         if (conf->min_offset_diff < 0) {
5733                 safepos += -conf->min_offset_diff;
5734                 readpos += -conf->min_offset_diff;
5735         } else
5736                 writepos += conf->min_offset_diff;
5737
5738         if ((mddev->reshape_backwards
5739              ? (safepos > writepos && readpos < writepos)
5740              : (safepos < writepos && readpos > writepos)) ||
5741             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
5742                 /* Cannot proceed until we've updated the superblock... */
5743                 wait_event(conf->wait_for_overlap,
5744                            atomic_read(&conf->reshape_stripes)==0
5745                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5746                 if (atomic_read(&conf->reshape_stripes) != 0)
5747                         return 0;
5748                 mddev->reshape_position = conf->reshape_progress;
5749                 mddev->curr_resync_completed = sector_nr;
5750                 conf->reshape_checkpoint = jiffies;
5751                 set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
5752                 md_wakeup_thread(mddev->thread);
5753                 wait_event(mddev->sb_wait, mddev->sb_flags == 0 ||
5754                            test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5755                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5756                         return 0;
5757                 spin_lock_irq(&conf->device_lock);
5758                 conf->reshape_safe = mddev->reshape_position;
5759                 spin_unlock_irq(&conf->device_lock);
5760                 wake_up(&conf->wait_for_overlap);
5761                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5762         }
5763
5764         INIT_LIST_HEAD(&stripes);
5765         for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
5766                 int j;
5767                 int skipped_disk = 0;
5768                 sh = raid5_get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
5769                 set_bit(STRIPE_EXPANDING, &sh->state);
5770                 atomic_inc(&conf->reshape_stripes);
5771                 /* If any of this stripe is beyond the end of the old
5772                  * array, then we need to zero those blocks
5773                  */
5774                 for (j=sh->disks; j--;) {
5775                         sector_t s;
5776                         if (j == sh->pd_idx)
5777                                 continue;
5778                         if (conf->level == 6 &&
5779                             j == sh->qd_idx)
5780                                 continue;
5781                         s = raid5_compute_blocknr(sh, j, 0);
5782                         if (s < raid5_size(mddev, 0, 0)) {
5783                                 skipped_disk = 1;
5784                                 continue;
5785                         }
5786                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
5787                         set_bit(R5_Expanded, &sh->dev[j].flags);
5788                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
5789                 }
5790                 if (!skipped_disk) {
5791                         set_bit(STRIPE_EXPAND_READY, &sh->state);
5792                         set_bit(STRIPE_HANDLE, &sh->state);
5793                 }
5794                 list_add(&sh->lru, &stripes);
5795         }
5796         spin_lock_irq(&conf->device_lock);
5797         if (mddev->reshape_backwards)
5798                 conf->reshape_progress -= reshape_sectors * new_data_disks;
5799         else
5800                 conf->reshape_progress += reshape_sectors * new_data_disks;
5801         spin_unlock_irq(&conf->device_lock);
5802         /* Ok, those stripe are ready. We can start scheduling
5803          * reads on the source stripes.
5804          * The source stripes are determined by mapping the first and last
5805          * block on the destination stripes.
5806          */
5807         first_sector =
5808                 raid5_compute_sector(conf, stripe_addr*(new_data_disks),
5809                                      1, &dd_idx, NULL);
5810         last_sector =
5811                 raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
5812                                             * new_data_disks - 1),
5813                                      1, &dd_idx, NULL);
5814         if (last_sector >= mddev->dev_sectors)
5815                 last_sector = mddev->dev_sectors - 1;
5816         while (first_sector <= last_sector) {
5817                 sh = raid5_get_active_stripe(conf, first_sector, 1, 0, 1);
5818                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
5819                 set_bit(STRIPE_HANDLE, &sh->state);
5820                 raid5_release_stripe(sh);
5821                 first_sector += STRIPE_SECTORS;
5822         }
5823         /* Now that the sources are clearly marked, we can release
5824          * the destination stripes
5825          */
5826         while (!list_empty(&stripes)) {
5827                 sh = list_entry(stripes.next, struct stripe_head, lru);
5828                 list_del_init(&sh->lru);
5829                 raid5_release_stripe(sh);
5830         }
5831         /* If this takes us to the resync_max point where we have to pause,
5832          * then we need to write out the superblock.
5833          */
5834         sector_nr += reshape_sectors;
5835         retn = reshape_sectors;
5836 finish:
5837         if (mddev->curr_resync_completed > mddev->resync_max ||
5838             (sector_nr - mddev->curr_resync_completed) * 2
5839             >= mddev->resync_max - mddev->curr_resync_completed) {
5840                 /* Cannot proceed until we've updated the superblock... */
5841                 wait_event(conf->wait_for_overlap,
5842                            atomic_read(&conf->reshape_stripes) == 0
5843                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5844                 if (atomic_read(&conf->reshape_stripes) != 0)
5845                         goto ret;
5846                 mddev->reshape_position = conf->reshape_progress;
5847                 mddev->curr_resync_completed = sector_nr;
5848                 conf->reshape_checkpoint = jiffies;
5849                 set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
5850                 md_wakeup_thread(mddev->thread);
5851                 wait_event(mddev->sb_wait,
5852                            !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags)
5853                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5854                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5855                         goto ret;
5856                 spin_lock_irq(&conf->device_lock);
5857                 conf->reshape_safe = mddev->reshape_position;
5858                 spin_unlock_irq(&conf->device_lock);
5859                 wake_up(&conf->wait_for_overlap);
5860                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5861         }
5862 ret:
5863         return retn;
5864 }
5865
5866 static inline sector_t raid5_sync_request(struct mddev *mddev, sector_t sector_nr,
5867                                           int *skipped)
5868 {
5869         struct r5conf *conf = mddev->private;
5870         struct stripe_head *sh;
5871         sector_t max_sector = mddev->dev_sectors;
5872         sector_t sync_blocks;
5873         int still_degraded = 0;
5874         int i;
5875
5876         if (sector_nr >= max_sector) {
5877                 /* just being told to finish up .. nothing much to do */
5878
5879                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
5880                         end_reshape(conf);
5881                         return 0;
5882                 }
5883
5884                 if (mddev->curr_resync < max_sector) /* aborted */
5885                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
5886                                         &sync_blocks, 1);
5887                 else /* completed sync */
5888                         conf->fullsync = 0;
5889                 bitmap_close_sync(mddev->bitmap);
5890
5891                 return 0;
5892         }
5893
5894         /* Allow raid5_quiesce to complete */
5895         wait_event(conf->wait_for_overlap, conf->quiesce != 2);
5896
5897         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
5898                 return reshape_request(mddev, sector_nr, skipped);
5899
5900         /* No need to check resync_max as we never do more than one
5901          * stripe, and as resync_max will always be on a chunk boundary,
5902          * if the check in md_do_sync didn't fire, there is no chance
5903          * of overstepping resync_max here
5904          */
5905
5906         /* if there is too many failed drives and we are trying
5907          * to resync, then assert that we are finished, because there is
5908          * nothing we can do.
5909          */
5910         if (mddev->degraded >= conf->max_degraded &&
5911             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
5912                 sector_t rv = mddev->dev_sectors - sector_nr;
5913                 *skipped = 1;
5914                 return rv;
5915         }
5916         if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
5917             !conf->fullsync &&
5918             !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
5919             sync_blocks >= STRIPE_SECTORS) {
5920                 /* we can skip this block, and probably more */
5921                 sync_blocks /= STRIPE_SECTORS;
5922                 *skipped = 1;
5923                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
5924         }
5925
5926         bitmap_cond_end_sync(mddev->bitmap, sector_nr, false);
5927
5928         sh = raid5_get_active_stripe(conf, sector_nr, 0, 1, 0);
5929         if (sh == NULL) {
5930                 sh = raid5_get_active_stripe(conf, sector_nr, 0, 0, 0);
5931                 /* make sure we don't swamp the stripe cache if someone else
5932                  * is trying to get access
5933                  */
5934                 schedule_timeout_uninterruptible(1);
5935         }
5936         /* Need to check if array will still be degraded after recovery/resync
5937          * Note in case of > 1 drive failures it's possible we're rebuilding
5938          * one drive while leaving another faulty drive in array.
5939          */
5940         rcu_read_lock();
5941         for (i = 0; i < conf->raid_disks; i++) {
5942                 struct md_rdev *rdev = ACCESS_ONCE(conf->disks[i].rdev);
5943
5944                 if (rdev == NULL || test_bit(Faulty, &rdev->flags))
5945                         still_degraded = 1;
5946         }
5947         rcu_read_unlock();
5948
5949         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
5950
5951         set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
5952         set_bit(STRIPE_HANDLE, &sh->state);
5953
5954         raid5_release_stripe(sh);
5955
5956         return STRIPE_SECTORS;
5957 }
5958
5959 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
5960 {
5961         /* We may not be able to submit a whole bio at once as there
5962          * may not be enough stripe_heads available.
5963          * We cannot pre-allocate enough stripe_heads as we may need
5964          * more than exist in the cache (if we allow ever large chunks).
5965          * So we do one stripe head at a time and record in
5966          * ->bi_hw_segments how many have been done.
5967          *
5968          * We *know* that this entire raid_bio is in one chunk, so
5969          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
5970          */
5971         struct stripe_head *sh;
5972         int dd_idx;
5973         sector_t sector, logical_sector, last_sector;
5974         int scnt = 0;
5975         int remaining;
5976         int handled = 0;
5977
5978         logical_sector = raid_bio->bi_iter.bi_sector &
5979                 ~((sector_t)STRIPE_SECTORS-1);
5980         sector = raid5_compute_sector(conf, logical_sector,
5981                                       0, &dd_idx, NULL);
5982         last_sector = bio_end_sector(raid_bio);
5983
5984         for (; logical_sector < last_sector;
5985              logical_sector += STRIPE_SECTORS,
5986                      sector += STRIPE_SECTORS,
5987                      scnt++) {
5988
5989                 if (scnt < raid5_bi_processed_stripes(raid_bio))
5990                         /* already done this stripe */
5991                         continue;
5992
5993                 sh = raid5_get_active_stripe(conf, sector, 0, 1, 1);
5994
5995                 if (!sh) {
5996                         /* failed to get a stripe - must wait */
5997                         raid5_set_bi_processed_stripes(raid_bio, scnt);
5998                         conf->retry_read_aligned = raid_bio;
5999                         return handled;
6000                 }
6001
6002                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
6003                         raid5_release_stripe(sh);
6004                         raid5_set_bi_processed_stripes(raid_bio, scnt);
6005                         conf->retry_read_aligned = raid_bio;
6006                         return handled;
6007                 }
6008
6009                 set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
6010                 handle_stripe(sh);
6011                 raid5_release_stripe(sh);
6012                 handled++;
6013         }
6014         remaining = raid5_dec_bi_active_stripes(raid_bio);
6015         if (remaining == 0) {
6016                 trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
6017                                          raid_bio, 0);
6018                 bio_endio(raid_bio);
6019         }
6020         if (atomic_dec_and_test(&conf->active_aligned_reads))
6021                 wake_up(&conf->wait_for_quiescent);
6022         return handled;
6023 }
6024
6025 static int handle_active_stripes(struct r5conf *conf, int group,
6026                                  struct r5worker *worker,
6027                                  struct list_head *temp_inactive_list)
6028 {
6029         struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
6030         int i, batch_size = 0, hash;
6031         bool release_inactive = false;
6032
6033         while (batch_size < MAX_STRIPE_BATCH &&
6034                         (sh = __get_priority_stripe(conf, group)) != NULL)
6035                 batch[batch_size++] = sh;
6036
6037         if (batch_size == 0) {
6038                 for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6039                         if (!list_empty(temp_inactive_list + i))
6040                                 break;
6041                 if (i == NR_STRIPE_HASH_LOCKS) {
6042                         spin_unlock_irq(&conf->device_lock);
6043                         r5l_flush_stripe_to_raid(conf->log);
6044                         spin_lock_irq(&conf->device_lock);
6045                         return batch_size;
6046                 }
6047                 release_inactive = true;
6048         }
6049         spin_unlock_irq(&conf->device_lock);
6050
6051         release_inactive_stripe_list(conf, temp_inactive_list,
6052                                      NR_STRIPE_HASH_LOCKS);
6053
6054         r5l_flush_stripe_to_raid(conf->log);
6055         if (release_inactive) {
6056                 spin_lock_irq(&conf->device_lock);
6057                 return 0;
6058         }
6059
6060         for (i = 0; i < batch_size; i++)
6061                 handle_stripe(batch[i]);
6062         r5l_write_stripe_run(conf->log);
6063
6064         cond_resched();
6065
6066         spin_lock_irq(&conf->device_lock);
6067         for (i = 0; i < batch_size; i++) {
6068                 hash = batch[i]->hash_lock_index;
6069                 __release_stripe(conf, batch[i], &temp_inactive_list[hash]);
6070         }
6071         return batch_size;
6072 }
6073
6074 static void raid5_do_work(struct work_struct *work)
6075 {
6076         struct r5worker *worker = container_of(work, struct r5worker, work);
6077         struct r5worker_group *group = worker->group;
6078         struct r5conf *conf = group->conf;
6079         int group_id = group - conf->worker_groups;
6080         int handled;
6081         struct blk_plug plug;
6082
6083         pr_debug("+++ raid5worker active\n");
6084
6085         blk_start_plug(&plug);
6086         handled = 0;
6087         spin_lock_irq(&conf->device_lock);
6088         while (1) {
6089                 int batch_size, released;
6090
6091                 released = release_stripe_list(conf, worker->temp_inactive_list);
6092
6093                 batch_size = handle_active_stripes(conf, group_id, worker,
6094                                                    worker->temp_inactive_list);
6095                 worker->working = false;
6096                 if (!batch_size && !released)
6097                         break;
6098                 handled += batch_size;
6099         }
6100         pr_debug("%d stripes handled\n", handled);
6101
6102         spin_unlock_irq(&conf->device_lock);
6103         blk_finish_plug(&plug);
6104
6105         pr_debug("--- raid5worker inactive\n");
6106 }
6107
6108 /*
6109  * This is our raid5 kernel thread.
6110  *
6111  * We scan the hash table for stripes which can be handled now.
6112  * During the scan, completed stripes are saved for us by the interrupt
6113  * handler, so that they will not have to wait for our next wakeup.
6114  */
6115 static void raid5d(struct md_thread *thread)
6116 {
6117         struct mddev *mddev = thread->mddev;
6118         struct r5conf *conf = mddev->private;
6119         int handled;
6120         struct blk_plug plug;
6121
6122         pr_debug("+++ raid5d active\n");
6123
6124         md_check_recovery(mddev);
6125
6126         if (!bio_list_empty(&conf->return_bi) &&
6127             !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
6128                 struct bio_list tmp = BIO_EMPTY_LIST;
6129                 spin_lock_irq(&conf->device_lock);
6130                 if (!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
6131                         bio_list_merge(&tmp, &conf->return_bi);
6132                         bio_list_init(&conf->return_bi);
6133                 }
6134                 spin_unlock_irq(&conf->device_lock);
6135                 return_io(&tmp);
6136         }
6137
6138         blk_start_plug(&plug);
6139         handled = 0;
6140         spin_lock_irq(&conf->device_lock);
6141         while (1) {
6142                 struct bio *bio;
6143                 int batch_size, released;
6144
6145                 released = release_stripe_list(conf, conf->temp_inactive_list);
6146                 if (released)
6147                         clear_bit(R5_DID_ALLOC, &conf->cache_state);
6148
6149                 if (
6150                     !list_empty(&conf->bitmap_list)) {
6151                         /* Now is a good time to flush some bitmap updates */
6152                         conf->seq_flush++;
6153                         spin_unlock_irq(&conf->device_lock);
6154                         bitmap_unplug(mddev->bitmap);
6155                         spin_lock_irq(&conf->device_lock);
6156                         conf->seq_write = conf->seq_flush;
6157                         activate_bit_delay(conf, conf->temp_inactive_list);
6158                 }
6159                 raid5_activate_delayed(conf);
6160
6161                 while ((bio = remove_bio_from_retry(conf))) {
6162                         int ok;
6163                         spin_unlock_irq(&conf->device_lock);
6164                         ok = retry_aligned_read(conf, bio);
6165                         spin_lock_irq(&conf->device_lock);
6166                         if (!ok)
6167                                 break;
6168                         handled++;
6169                 }
6170
6171                 batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
6172                                                    conf->temp_inactive_list);
6173                 if (!batch_size && !released)
6174                         break;
6175                 handled += batch_size;
6176
6177                 if (mddev->sb_flags & ~(1 << MD_SB_CHANGE_PENDING)) {
6178                         spin_unlock_irq(&conf->device_lock);
6179                         md_check_recovery(mddev);
6180                         spin_lock_irq(&conf->device_lock);
6181                 }
6182         }
6183         pr_debug("%d stripes handled\n", handled);
6184
6185         spin_unlock_irq(&conf->device_lock);
6186         if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state) &&
6187             mutex_trylock(&conf->cache_size_mutex)) {
6188                 grow_one_stripe(conf, __GFP_NOWARN);
6189                 /* Set flag even if allocation failed.  This helps
6190                  * slow down allocation requests when mem is short
6191                  */
6192                 set_bit(R5_DID_ALLOC, &conf->cache_state);
6193                 mutex_unlock(&conf->cache_size_mutex);
6194         }
6195
6196         flush_deferred_bios(conf);
6197
6198         r5l_flush_stripe_to_raid(conf->log);
6199
6200         async_tx_issue_pending_all();
6201         blk_finish_plug(&plug);
6202
6203         pr_debug("--- raid5d inactive\n");
6204 }
6205
6206 static ssize_t
6207 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
6208 {
6209         struct r5conf *conf;
6210         int ret = 0;
6211         spin_lock(&mddev->lock);
6212         conf = mddev->private;
6213         if (conf)
6214                 ret = sprintf(page, "%d\n", conf->min_nr_stripes);
6215         spin_unlock(&mddev->lock);
6216         return ret;
6217 }
6218
6219 int
6220 raid5_set_cache_size(struct mddev *mddev, int size)
6221 {
6222         struct r5conf *conf = mddev->private;
6223         int err;
6224
6225         if (size <= 16 || size > 32768)
6226                 return -EINVAL;
6227
6228         conf->min_nr_stripes = size;
6229         mutex_lock(&conf->cache_size_mutex);
6230         while (size < conf->max_nr_stripes &&
6231                drop_one_stripe(conf))
6232                 ;
6233         mutex_unlock(&conf->cache_size_mutex);
6234
6235
6236         err = md_allow_write(mddev);
6237         if (err)
6238                 return err;
6239
6240         mutex_lock(&conf->cache_size_mutex);
6241         while (size > conf->max_nr_stripes)
6242                 if (!grow_one_stripe(conf, GFP_KERNEL))
6243                         break;
6244         mutex_unlock(&conf->cache_size_mutex);
6245
6246         return 0;
6247 }
6248 EXPORT_SYMBOL(raid5_set_cache_size);
6249
6250 static ssize_t
6251 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
6252 {
6253         struct r5conf *conf;
6254         unsigned long new;
6255         int err;
6256
6257         if (len >= PAGE_SIZE)
6258                 return -EINVAL;
6259         if (kstrtoul(page, 10, &new))
6260                 return -EINVAL;
6261         err = mddev_lock(mddev);
6262         if (err)
6263                 return err;
6264         conf = mddev->private;
6265         if (!conf)
6266                 err = -ENODEV;
6267         else
6268                 err = raid5_set_cache_size(mddev, new);
6269         mddev_unlock(mddev);
6270
6271         return err ?: len;
6272 }
6273
6274 static struct md_sysfs_entry
6275 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
6276                                 raid5_show_stripe_cache_size,
6277                                 raid5_store_stripe_cache_size);
6278
6279 static ssize_t
6280 raid5_show_rmw_level(struct mddev  *mddev, char *page)
6281 {
6282         struct r5conf *conf = mddev->private;
6283         if (conf)
6284                 return sprintf(page, "%d\n", conf->rmw_level);
6285         else
6286                 return 0;
6287 }
6288
6289 static ssize_t
6290 raid5_store_rmw_level(struct mddev  *mddev, const char *page, size_t len)
6291 {
6292         struct r5conf *conf = mddev->private;
6293         unsigned long new;
6294
6295         if (!conf)
6296                 return -ENODEV;
6297
6298         if (len >= PAGE_SIZE)
6299                 return -EINVAL;
6300
6301         if (kstrtoul(page, 10, &new))
6302                 return -EINVAL;
6303
6304         if (new != PARITY_DISABLE_RMW && !raid6_call.xor_syndrome)
6305                 return -EINVAL;
6306
6307         if (new != PARITY_DISABLE_RMW &&
6308             new != PARITY_ENABLE_RMW &&
6309             new != PARITY_PREFER_RMW)
6310                 return -EINVAL;
6311
6312         conf->rmw_level = new;
6313         return len;
6314 }
6315
6316 static struct md_sysfs_entry
6317 raid5_rmw_level = __ATTR(rmw_level, S_IRUGO | S_IWUSR,
6318                          raid5_show_rmw_level,
6319                          raid5_store_rmw_level);
6320
6321
6322 static ssize_t
6323 raid5_show_preread_threshold(struct mddev *mddev, char *page)
6324 {
6325         struct r5conf *conf;
6326         int ret = 0;
6327         spin_lock(&mddev->lock);
6328         conf = mddev->private;
6329         if (conf)
6330                 ret = sprintf(page, "%d\n", conf->bypass_threshold);
6331         spin_unlock(&mddev->lock);
6332         return ret;
6333 }
6334
6335 static ssize_t
6336 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
6337 {
6338         struct r5conf *conf;
6339         unsigned long new;
6340         int err;
6341
6342         if (len >= PAGE_SIZE)
6343                 return -EINVAL;
6344         if (kstrtoul(page, 10, &new))
6345                 return -EINVAL;
6346
6347         err = mddev_lock(mddev);
6348         if (err)
6349                 return err;
6350         conf = mddev->private;
6351         if (!conf)
6352                 err = -ENODEV;
6353         else if (new > conf->min_nr_stripes)
6354                 err = -EINVAL;
6355         else
6356                 conf->bypass_threshold = new;
6357         mddev_unlock(mddev);
6358         return err ?: len;
6359 }
6360
6361 static struct md_sysfs_entry
6362 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
6363                                         S_IRUGO | S_IWUSR,
6364                                         raid5_show_preread_threshold,
6365                                         raid5_store_preread_threshold);
6366
6367 static ssize_t
6368 raid5_show_skip_copy(struct mddev *mddev, char *page)
6369 {
6370         struct r5conf *conf;
6371         int ret = 0;
6372         spin_lock(&mddev->lock);
6373         conf = mddev->private;
6374         if (conf)
6375                 ret = sprintf(page, "%d\n", conf->skip_copy);
6376         spin_unlock(&mddev->lock);
6377         return ret;
6378 }
6379
6380 static ssize_t
6381 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
6382 {
6383         struct r5conf *conf;
6384         unsigned long new;
6385         int err;
6386
6387         if (len >= PAGE_SIZE)
6388                 return -EINVAL;
6389         if (kstrtoul(page, 10, &new))
6390                 return -EINVAL;
6391         new = !!new;
6392
6393         err = mddev_lock(mddev);
6394         if (err)
6395                 return err;
6396         conf = mddev->private;
6397         if (!conf)
6398                 err = -ENODEV;
6399         else if (new != conf->skip_copy) {
6400                 mddev_suspend(mddev);
6401                 conf->skip_copy = new;
6402                 if (new)
6403                         mddev->queue->backing_dev_info->capabilities |=
6404                                 BDI_CAP_STABLE_WRITES;
6405                 else
6406                         mddev->queue->backing_dev_info->capabilities &=
6407                                 ~BDI_CAP_STABLE_WRITES;
6408                 mddev_resume(mddev);
6409         }
6410         mddev_unlock(mddev);
6411         return err ?: len;
6412 }
6413
6414 static struct md_sysfs_entry
6415 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
6416                                         raid5_show_skip_copy,
6417                                         raid5_store_skip_copy);
6418
6419 static ssize_t
6420 stripe_cache_active_show(struct mddev *mddev, char *page)
6421 {
6422         struct r5conf *conf = mddev->private;
6423         if (conf)
6424                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
6425         else
6426                 return 0;
6427 }
6428
6429 static struct md_sysfs_entry
6430 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
6431
6432 static ssize_t
6433 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
6434 {
6435         struct r5conf *conf;
6436         int ret = 0;
6437         spin_lock(&mddev->lock);
6438         conf = mddev->private;
6439         if (conf)
6440                 ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
6441         spin_unlock(&mddev->lock);
6442         return ret;
6443 }
6444
6445 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6446                                int *group_cnt,
6447                                int *worker_cnt_per_group,
6448                                struct r5worker_group **worker_groups);
6449 static ssize_t
6450 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
6451 {
6452         struct r5conf *conf;
6453         unsigned long new;
6454         int err;
6455         struct r5worker_group *new_groups, *old_groups;
6456         int group_cnt, worker_cnt_per_group;
6457
6458         if (len >= PAGE_SIZE)
6459                 return -EINVAL;
6460         if (kstrtoul(page, 10, &new))
6461                 return -EINVAL;
6462
6463         err = mddev_lock(mddev);
6464         if (err)
6465                 return err;
6466         conf = mddev->private;
6467         if (!conf)
6468                 err = -ENODEV;
6469         else if (new != conf->worker_cnt_per_group) {
6470                 mddev_suspend(mddev);
6471
6472                 old_groups = conf->worker_groups;
6473                 if (old_groups)
6474                         flush_workqueue(raid5_wq);
6475
6476                 err = alloc_thread_groups(conf, new,
6477                                           &group_cnt, &worker_cnt_per_group,
6478                                           &new_groups);
6479                 if (!err) {
6480                         spin_lock_irq(&conf->device_lock);
6481                         conf->group_cnt = group_cnt;
6482                         conf->worker_cnt_per_group = worker_cnt_per_group;
6483                         conf->worker_groups = new_groups;
6484                         spin_unlock_irq(&conf->device_lock);
6485
6486                         if (old_groups)
6487                                 kfree(old_groups[0].workers);
6488                         kfree(old_groups);
6489                 }
6490                 mddev_resume(mddev);
6491         }
6492         mddev_unlock(mddev);
6493
6494         return err ?: len;
6495 }
6496
6497 static struct md_sysfs_entry
6498 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
6499                                 raid5_show_group_thread_cnt,
6500                                 raid5_store_group_thread_cnt);
6501
6502 static struct attribute *raid5_attrs[] =  {
6503         &raid5_stripecache_size.attr,
6504         &raid5_stripecache_active.attr,
6505         &raid5_preread_bypass_threshold.attr,
6506         &raid5_group_thread_cnt.attr,
6507         &raid5_skip_copy.attr,
6508         &raid5_rmw_level.attr,
6509         &r5c_journal_mode.attr,
6510         NULL,
6511 };
6512 static struct attribute_group raid5_attrs_group = {
6513         .name = NULL,
6514         .attrs = raid5_attrs,
6515 };
6516
6517 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6518                                int *group_cnt,
6519                                int *worker_cnt_per_group,
6520                                struct r5worker_group **worker_groups)
6521 {
6522         int i, j, k;
6523         ssize_t size;
6524         struct r5worker *workers;
6525
6526         *worker_cnt_per_group = cnt;
6527         if (cnt == 0) {
6528                 *group_cnt = 0;
6529                 *worker_groups = NULL;
6530                 return 0;
6531         }
6532         *group_cnt = num_possible_nodes();
6533         size = sizeof(struct r5worker) * cnt;
6534         workers = kzalloc(size * *group_cnt, GFP_NOIO);
6535         *worker_groups = kzalloc(sizeof(struct r5worker_group) *
6536                                 *group_cnt, GFP_NOIO);
6537         if (!*worker_groups || !workers) {
6538                 kfree(workers);
6539                 kfree(*worker_groups);
6540                 return -ENOMEM;
6541         }
6542
6543         for (i = 0; i < *group_cnt; i++) {
6544                 struct r5worker_group *group;
6545
6546                 group = &(*worker_groups)[i];
6547                 INIT_LIST_HEAD(&group->handle_list);
6548                 group->conf = conf;
6549                 group->workers = workers + i * cnt;
6550
6551                 for (j = 0; j < cnt; j++) {
6552                         struct r5worker *worker = group->workers + j;
6553                         worker->group = group;
6554                         INIT_WORK(&worker->work, raid5_do_work);
6555
6556                         for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
6557                                 INIT_LIST_HEAD(worker->temp_inactive_list + k);
6558                 }
6559         }
6560
6561         return 0;
6562 }
6563
6564 static void free_thread_groups(struct r5conf *conf)
6565 {
6566         if (conf->worker_groups)
6567                 kfree(conf->worker_groups[0].workers);
6568         kfree(conf->worker_groups);
6569         conf->worker_groups = NULL;
6570 }
6571
6572 static sector_t
6573 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
6574 {
6575         struct r5conf *conf = mddev->private;
6576
6577         if (!sectors)
6578                 sectors = mddev->dev_sectors;
6579         if (!raid_disks)
6580                 /* size is defined by the smallest of previous and new size */
6581                 raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
6582
6583         sectors &= ~((sector_t)conf->chunk_sectors - 1);
6584         sectors &= ~((sector_t)conf->prev_chunk_sectors - 1);
6585         return sectors * (raid_disks - conf->max_degraded);
6586 }
6587
6588 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6589 {
6590         safe_put_page(percpu->spare_page);
6591         if (percpu->scribble)
6592                 flex_array_free(percpu->scribble);
6593         percpu->spare_page = NULL;
6594         percpu->scribble = NULL;
6595 }
6596
6597 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6598 {
6599         if (conf->level == 6 && !percpu->spare_page)
6600                 percpu->spare_page = alloc_page(GFP_KERNEL);
6601         if (!percpu->scribble)
6602                 percpu->scribble = scribble_alloc(max(conf->raid_disks,
6603                                                       conf->previous_raid_disks),
6604                                                   max(conf->chunk_sectors,
6605                                                       conf->prev_chunk_sectors)
6606                                                    / STRIPE_SECTORS,
6607                                                   GFP_KERNEL);
6608
6609         if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
6610                 free_scratch_buffer(conf, percpu);
6611                 return -ENOMEM;
6612         }
6613
6614         return 0;
6615 }
6616
6617 static int raid456_cpu_dead(unsigned int cpu, struct hlist_node *node)
6618 {
6619         struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
6620
6621         free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6622         return 0;
6623 }
6624
6625 static void raid5_free_percpu(struct r5conf *conf)
6626 {
6627         if (!conf->percpu)
6628                 return;
6629
6630         cpuhp_state_remove_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
6631         free_percpu(conf->percpu);
6632 }
6633
6634 static void free_conf(struct r5conf *conf)
6635 {
6636         int i;
6637
6638         if (conf->log)
6639                 r5l_exit_log(conf->log);
6640         if (conf->shrinker.nr_deferred)
6641                 unregister_shrinker(&conf->shrinker);
6642
6643         free_thread_groups(conf);
6644         shrink_stripes(conf);
6645         raid5_free_percpu(conf);
6646         for (i = 0; i < conf->pool_size; i++)
6647                 if (conf->disks[i].extra_page)
6648                         put_page(conf->disks[i].extra_page);
6649         kfree(conf->disks);
6650         kfree(conf->stripe_hashtbl);
6651         kfree(conf);
6652 }
6653
6654 static int raid456_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
6655 {
6656         struct r5conf *conf = hlist_entry_safe(node, struct r5conf, node);
6657         struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
6658
6659         if (alloc_scratch_buffer(conf, percpu)) {
6660                 pr_warn("%s: failed memory allocation for cpu%u\n",
6661                         __func__, cpu);
6662                 return -ENOMEM;
6663         }
6664         return 0;
6665 }
6666
6667 static int raid5_alloc_percpu(struct r5conf *conf)
6668 {
6669         int err = 0;
6670
6671         conf->percpu = alloc_percpu(struct raid5_percpu);
6672         if (!conf->percpu)
6673                 return -ENOMEM;
6674
6675         err = cpuhp_state_add_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
6676         if (!err) {
6677                 conf->scribble_disks = max(conf->raid_disks,
6678                         conf->previous_raid_disks);
6679                 conf->scribble_sectors = max(conf->chunk_sectors,
6680                         conf->prev_chunk_sectors);
6681         }
6682         return err;
6683 }
6684
6685 static unsigned long raid5_cache_scan(struct shrinker *shrink,
6686                                       struct shrink_control *sc)
6687 {
6688         struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6689         unsigned long ret = SHRINK_STOP;
6690
6691         if (mutex_trylock(&conf->cache_size_mutex)) {
6692                 ret= 0;
6693                 while (ret < sc->nr_to_scan &&
6694                        conf->max_nr_stripes > conf->min_nr_stripes) {
6695                         if (drop_one_stripe(conf) == 0) {
6696                                 ret = SHRINK_STOP;
6697                                 break;
6698                         }
6699                         ret++;
6700                 }
6701                 mutex_unlock(&conf->cache_size_mutex);
6702         }
6703         return ret;
6704 }
6705
6706 static unsigned long raid5_cache_count(struct shrinker *shrink,
6707                                        struct shrink_control *sc)
6708 {
6709         struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6710
6711         if (conf->max_nr_stripes < conf->min_nr_stripes)
6712                 /* unlikely, but not impossible */
6713                 return 0;
6714         return conf->max_nr_stripes - conf->min_nr_stripes;
6715 }
6716
6717 static struct r5conf *setup_conf(struct mddev *mddev)
6718 {
6719         struct r5conf *conf;
6720         int raid_disk, memory, max_disks;
6721         struct md_rdev *rdev;
6722         struct disk_info *disk;
6723         char pers_name[6];
6724         int i;
6725         int group_cnt, worker_cnt_per_group;
6726         struct r5worker_group *new_group;
6727
6728         if (mddev->new_level != 5
6729             && mddev->new_level != 4
6730             && mddev->new_level != 6) {
6731                 pr_warn("md/raid:%s: raid level not set to 4/5/6 (%d)\n",
6732                         mdname(mddev), mddev->new_level);
6733                 return ERR_PTR(-EIO);
6734         }
6735         if ((mddev->new_level == 5
6736              && !algorithm_valid_raid5(mddev->new_layout)) ||
6737             (mddev->new_level == 6
6738              && !algorithm_valid_raid6(mddev->new_layout))) {
6739                 pr_warn("md/raid:%s: layout %d not supported\n",
6740                         mdname(mddev), mddev->new_layout);
6741                 return ERR_PTR(-EIO);
6742         }
6743         if (mddev->new_level == 6 && mddev->raid_disks < 4) {
6744                 pr_warn("md/raid:%s: not enough configured devices (%d, minimum 4)\n",
6745                         mdname(mddev), mddev->raid_disks);
6746                 return ERR_PTR(-EINVAL);
6747         }
6748
6749         if (!mddev->new_chunk_sectors ||
6750             (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
6751             !is_power_of_2(mddev->new_chunk_sectors)) {
6752                 pr_warn("md/raid:%s: invalid chunk size %d\n",
6753                         mdname(mddev), mddev->new_chunk_sectors << 9);
6754                 return ERR_PTR(-EINVAL);
6755         }
6756
6757         conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
6758         if (conf == NULL)
6759                 goto abort;
6760         /* Don't enable multi-threading by default*/
6761         if (!alloc_thread_groups(conf, 0, &group_cnt, &worker_cnt_per_group,
6762                                  &new_group)) {
6763                 conf->group_cnt = group_cnt;
6764                 conf->worker_cnt_per_group = worker_cnt_per_group;
6765                 conf->worker_groups = new_group;
6766         } else
6767                 goto abort;
6768         spin_lock_init(&conf->device_lock);
6769         seqcount_init(&conf->gen_lock);
6770         mutex_init(&conf->cache_size_mutex);
6771         init_waitqueue_head(&conf->wait_for_quiescent);
6772         init_waitqueue_head(&conf->wait_for_stripe);
6773         init_waitqueue_head(&conf->wait_for_overlap);
6774         INIT_LIST_HEAD(&conf->handle_list);
6775         INIT_LIST_HEAD(&conf->hold_list);
6776         INIT_LIST_HEAD(&conf->delayed_list);
6777         INIT_LIST_HEAD(&conf->bitmap_list);
6778         bio_list_init(&conf->return_bi);
6779         init_llist_head(&conf->released_stripes);
6780         atomic_set(&conf->active_stripes, 0);
6781         atomic_set(&conf->preread_active_stripes, 0);
6782         atomic_set(&conf->active_aligned_reads, 0);
6783         bio_list_init(&conf->pending_bios);
6784         spin_lock_init(&conf->pending_bios_lock);
6785         conf->batch_bio_dispatch = true;
6786         rdev_for_each(rdev, mddev) {
6787                 if (test_bit(Journal, &rdev->flags))
6788                         continue;
6789                 if (blk_queue_nonrot(bdev_get_queue(rdev->bdev))) {
6790                         conf->batch_bio_dispatch = false;
6791                         break;
6792                 }
6793         }
6794
6795         conf->bypass_threshold = BYPASS_THRESHOLD;
6796         conf->recovery_disabled = mddev->recovery_disabled - 1;
6797
6798         conf->raid_disks = mddev->raid_disks;
6799         if (mddev->reshape_position == MaxSector)
6800                 conf->previous_raid_disks = mddev->raid_disks;
6801         else
6802                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
6803         max_disks = max(conf->raid_disks, conf->previous_raid_disks);
6804
6805         conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
6806                               GFP_KERNEL);
6807
6808         if (!conf->disks)
6809                 goto abort;
6810
6811         for (i = 0; i < max_disks; i++) {
6812                 conf->disks[i].extra_page = alloc_page(GFP_KERNEL);
6813                 if (!conf->disks[i].extra_page)
6814                         goto abort;
6815         }
6816
6817         conf->mddev = mddev;
6818
6819         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
6820                 goto abort;
6821
6822         /* We init hash_locks[0] separately to that it can be used
6823          * as the reference lock in the spin_lock_nest_lock() call
6824          * in lock_all_device_hash_locks_irq in order to convince
6825          * lockdep that we know what we are doing.
6826          */
6827         spin_lock_init(conf->hash_locks);
6828         for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
6829                 spin_lock_init(conf->hash_locks + i);
6830
6831         for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6832                 INIT_LIST_HEAD(conf->inactive_list + i);
6833
6834         for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6835                 INIT_LIST_HEAD(conf->temp_inactive_list + i);
6836
6837         atomic_set(&conf->r5c_cached_full_stripes, 0);
6838         INIT_LIST_HEAD(&conf->r5c_full_stripe_list);
6839         atomic_set(&conf->r5c_cached_partial_stripes, 0);
6840         INIT_LIST_HEAD(&conf->r5c_partial_stripe_list);
6841         atomic_set(&conf->r5c_flushing_full_stripes, 0);
6842         atomic_set(&conf->r5c_flushing_partial_stripes, 0);
6843
6844         conf->level = mddev->new_level;
6845         conf->chunk_sectors = mddev->new_chunk_sectors;
6846         if (raid5_alloc_percpu(conf) != 0)
6847                 goto abort;
6848
6849         pr_debug("raid456: run(%s) called.\n", mdname(mddev));
6850
6851         rdev_for_each(rdev, mddev) {
6852                 raid_disk = rdev->raid_disk;
6853                 if (raid_disk >= max_disks
6854                     || raid_disk < 0 || test_bit(Journal, &rdev->flags))
6855                         continue;
6856                 disk = conf->disks + raid_disk;
6857
6858                 if (test_bit(Replacement, &rdev->flags)) {
6859                         if (disk->replacement)
6860                                 goto abort;
6861                         disk->replacement = rdev;
6862                 } else {
6863                         if (disk->rdev)
6864                                 goto abort;
6865                         disk->rdev = rdev;
6866                 }
6867
6868                 if (test_bit(In_sync, &rdev->flags)) {
6869                         char b[BDEVNAME_SIZE];
6870                         pr_info("md/raid:%s: device %s operational as raid disk %d\n",
6871                                 mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
6872                 } else if (rdev->saved_raid_disk != raid_disk)
6873                         /* Cannot rely on bitmap to complete recovery */
6874                         conf->fullsync = 1;
6875         }
6876
6877         conf->level = mddev->new_level;
6878         if (conf->level == 6) {
6879                 conf->max_degraded = 2;
6880                 if (raid6_call.xor_syndrome)
6881                         conf->rmw_level = PARITY_ENABLE_RMW;
6882                 else
6883                         conf->rmw_level = PARITY_DISABLE_RMW;
6884         } else {
6885                 conf->max_degraded = 1;
6886                 conf->rmw_level = PARITY_ENABLE_RMW;
6887         }
6888         conf->algorithm = mddev->new_layout;
6889         conf->reshape_progress = mddev->reshape_position;
6890         if (conf->reshape_progress != MaxSector) {
6891                 conf->prev_chunk_sectors = mddev->chunk_sectors;
6892                 conf->prev_algo = mddev->layout;
6893         } else {
6894                 conf->prev_chunk_sectors = conf->chunk_sectors;
6895                 conf->prev_algo = conf->algorithm;
6896         }
6897
6898         conf->min_nr_stripes = NR_STRIPES;
6899         if (mddev->reshape_position != MaxSector) {
6900                 int stripes = max_t(int,
6901                         ((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4,
6902                         ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4);
6903                 conf->min_nr_stripes = max(NR_STRIPES, stripes);
6904                 if (conf->min_nr_stripes != NR_STRIPES)
6905                         pr_info("md/raid:%s: force stripe size %d for reshape\n",
6906                                 mdname(mddev), conf->min_nr_stripes);
6907         }
6908         memory = conf->min_nr_stripes * (sizeof(struct stripe_head) +
6909                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
6910         atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
6911         if (grow_stripes(conf, conf->min_nr_stripes)) {
6912                 pr_warn("md/raid:%s: couldn't allocate %dkB for buffers\n",
6913                         mdname(mddev), memory);
6914                 goto abort;
6915         } else
6916                 pr_debug("md/raid:%s: allocated %dkB\n", mdname(mddev), memory);
6917         /*
6918          * Losing a stripe head costs more than the time to refill it,
6919          * it reduces the queue depth and so can hurt throughput.
6920          * So set it rather large, scaled by number of devices.
6921          */
6922         conf->shrinker.seeks = DEFAULT_SEEKS * conf->raid_disks * 4;
6923         conf->shrinker.scan_objects = raid5_cache_scan;
6924         conf->shrinker.count_objects = raid5_cache_count;
6925         conf->shrinker.batch = 128;
6926         conf->shrinker.flags = 0;
6927         if (register_shrinker(&conf->shrinker)) {
6928                 pr_warn("md/raid:%s: couldn't register shrinker.\n",
6929                         mdname(mddev));
6930                 goto abort;
6931         }
6932
6933         sprintf(pers_name, "raid%d", mddev->new_level);
6934         conf->thread = md_register_thread(raid5d, mddev, pers_name);
6935         if (!conf->thread) {
6936                 pr_warn("md/raid:%s: couldn't allocate thread.\n",
6937                         mdname(mddev));
6938                 goto abort;
6939         }
6940
6941         return conf;
6942
6943  abort:
6944         if (conf) {
6945                 free_conf(conf);
6946                 return ERR_PTR(-EIO);
6947         } else
6948                 return ERR_PTR(-ENOMEM);
6949 }
6950
6951 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
6952 {
6953         switch (algo) {
6954         case ALGORITHM_PARITY_0:
6955                 if (raid_disk < max_degraded)
6956                         return 1;
6957                 break;
6958         case ALGORITHM_PARITY_N:
6959                 if (raid_disk >= raid_disks - max_degraded)
6960                         return 1;
6961                 break;
6962         case ALGORITHM_PARITY_0_6:
6963                 if (raid_disk == 0 ||
6964                     raid_disk == raid_disks - 1)
6965                         return 1;
6966                 break;
6967         case ALGORITHM_LEFT_ASYMMETRIC_6:
6968         case ALGORITHM_RIGHT_ASYMMETRIC_6:
6969         case ALGORITHM_LEFT_SYMMETRIC_6:
6970         case ALGORITHM_RIGHT_SYMMETRIC_6:
6971                 if (raid_disk == raid_disks - 1)
6972                         return 1;
6973         }
6974         return 0;
6975 }
6976
6977 static int raid5_run(struct mddev *mddev)
6978 {
6979         struct r5conf *conf;
6980         int working_disks = 0;
6981         int dirty_parity_disks = 0;
6982         struct md_rdev *rdev;
6983         struct md_rdev *journal_dev = NULL;
6984         sector_t reshape_offset = 0;
6985         int i;
6986         long long min_offset_diff = 0;
6987         int first = 1;
6988
6989         if (mddev->recovery_cp != MaxSector)
6990                 pr_notice("md/raid:%s: not clean -- starting background reconstruction\n",
6991                           mdname(mddev));
6992
6993         rdev_for_each(rdev, mddev) {
6994                 long long diff;
6995
6996                 if (test_bit(Journal, &rdev->flags)) {
6997                         journal_dev = rdev;
6998                         continue;
6999                 }
7000                 if (rdev->raid_disk < 0)
7001                         continue;
7002                 diff = (rdev->new_data_offset - rdev->data_offset);
7003                 if (first) {
7004                         min_offset_diff = diff;
7005                         first = 0;
7006                 } else if (mddev->reshape_backwards &&
7007                          diff < min_offset_diff)
7008                         min_offset_diff = diff;
7009                 else if (!mddev->reshape_backwards &&
7010                          diff > min_offset_diff)
7011                         min_offset_diff = diff;
7012         }
7013
7014         if (mddev->reshape_position != MaxSector) {
7015                 /* Check that we can continue the reshape.
7016                  * Difficulties arise if the stripe we would write to
7017                  * next is at or after the stripe we would read from next.
7018                  * For a reshape that changes the number of devices, this
7019                  * is only possible for a very short time, and mdadm makes
7020                  * sure that time appears to have past before assembling
7021                  * the array.  So we fail if that time hasn't passed.
7022                  * For a reshape that keeps the number of devices the same
7023                  * mdadm must be monitoring the reshape can keeping the
7024                  * critical areas read-only and backed up.  It will start
7025                  * the array in read-only mode, so we check for that.
7026                  */
7027                 sector_t here_new, here_old;
7028                 int old_disks;
7029                 int max_degraded = (mddev->level == 6 ? 2 : 1);
7030                 int chunk_sectors;
7031                 int new_data_disks;
7032
7033                 if (journal_dev) {
7034                         pr_warn("md/raid:%s: don't support reshape with journal - aborting.\n",
7035                                 mdname(mddev));
7036                         return -EINVAL;
7037                 }
7038
7039                 if (mddev->new_level != mddev->level) {
7040                         pr_warn("md/raid:%s: unsupported reshape required - aborting.\n",
7041                                 mdname(mddev));
7042                         return -EINVAL;
7043                 }
7044                 old_disks = mddev->raid_disks - mddev->delta_disks;
7045                 /* reshape_position must be on a new-stripe boundary, and one
7046                  * further up in new geometry must map after here in old
7047                  * geometry.
7048                  * If the chunk sizes are different, then as we perform reshape
7049                  * in units of the largest of the two, reshape_position needs
7050                  * be a multiple of the largest chunk size times new data disks.
7051                  */
7052                 here_new = mddev->reshape_position;
7053                 chunk_sectors = max(mddev->chunk_sectors, mddev->new_chunk_sectors);
7054                 new_data_disks = mddev->raid_disks - max_degraded;
7055                 if (sector_div(here_new, chunk_sectors * new_data_disks)) {
7056                         pr_warn("md/raid:%s: reshape_position not on a stripe boundary\n",
7057                                 mdname(mddev));
7058                         return -EINVAL;
7059                 }
7060                 reshape_offset = here_new * chunk_sectors;
7061                 /* here_new is the stripe we will write to */
7062                 here_old = mddev->reshape_position;
7063                 sector_div(here_old, chunk_sectors * (old_disks-max_degraded));
7064                 /* here_old is the first stripe that we might need to read
7065                  * from */
7066                 if (mddev->delta_disks == 0) {
7067                         /* We cannot be sure it is safe to start an in-place
7068                          * reshape.  It is only safe if user-space is monitoring
7069                          * and taking constant backups.
7070                          * mdadm always starts a situation like this in
7071                          * readonly mode so it can take control before
7072                          * allowing any writes.  So just check for that.
7073                          */
7074                         if (abs(min_offset_diff) >= mddev->chunk_sectors &&
7075                             abs(min_offset_diff) >= mddev->new_chunk_sectors)
7076                                 /* not really in-place - so OK */;
7077                         else if (mddev->ro == 0) {
7078                                 pr_warn("md/raid:%s: in-place reshape must be started in read-only mode - aborting\n",
7079                                         mdname(mddev));
7080                                 return -EINVAL;
7081                         }
7082                 } else if (mddev->reshape_backwards
7083                     ? (here_new * chunk_sectors + min_offset_diff <=
7084                        here_old * chunk_sectors)
7085                     : (here_new * chunk_sectors >=
7086                        here_old * chunk_sectors + (-min_offset_diff))) {
7087                         /* Reading from the same stripe as writing to - bad */
7088                         pr_warn("md/raid:%s: reshape_position too early for auto-recovery - aborting.\n",
7089                                 mdname(mddev));
7090                         return -EINVAL;
7091                 }
7092                 pr_debug("md/raid:%s: reshape will continue\n", mdname(mddev));
7093                 /* OK, we should be able to continue; */
7094         } else {
7095                 BUG_ON(mddev->level != mddev->new_level);
7096                 BUG_ON(mddev->layout != mddev->new_layout);
7097                 BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
7098                 BUG_ON(mddev->delta_disks != 0);
7099         }
7100
7101         if (mddev->private == NULL)
7102                 conf = setup_conf(mddev);
7103         else
7104                 conf = mddev->private;
7105
7106         if (IS_ERR(conf))
7107                 return PTR_ERR(conf);
7108
7109         if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
7110                 if (!journal_dev) {
7111                         pr_warn("md/raid:%s: journal disk is missing, force array readonly\n",
7112                                 mdname(mddev));
7113                         mddev->ro = 1;
7114                         set_disk_ro(mddev->gendisk, 1);
7115                 } else if (mddev->recovery_cp == MaxSector)
7116                         set_bit(MD_JOURNAL_CLEAN, &mddev->flags);
7117         }
7118
7119         conf->min_offset_diff = min_offset_diff;
7120         mddev->thread = conf->thread;
7121         conf->thread = NULL;
7122         mddev->private = conf;
7123
7124         for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
7125              i++) {
7126                 rdev = conf->disks[i].rdev;
7127                 if (!rdev && conf->disks[i].replacement) {
7128                         /* The replacement is all we have yet */
7129                         rdev = conf->disks[i].replacement;
7130                         conf->disks[i].replacement = NULL;
7131                         clear_bit(Replacement, &rdev->flags);
7132                         conf->disks[i].rdev = rdev;
7133                 }
7134                 if (!rdev)
7135                         continue;
7136                 if (conf->disks[i].replacement &&
7137                     conf->reshape_progress != MaxSector) {
7138                         /* replacements and reshape simply do not mix. */
7139                         pr_warn("md: cannot handle concurrent replacement and reshape.\n");
7140                         goto abort;
7141                 }
7142                 if (test_bit(In_sync, &rdev->flags)) {
7143                         working_disks++;
7144                         continue;
7145                 }
7146                 /* This disc is not fully in-sync.  However if it
7147                  * just stored parity (beyond the recovery_offset),
7148                  * when we don't need to be concerned about the
7149                  * array being dirty.
7150                  * When reshape goes 'backwards', we never have
7151                  * partially completed devices, so we only need
7152                  * to worry about reshape going forwards.
7153                  */
7154                 /* Hack because v0.91 doesn't store recovery_offset properly. */
7155                 if (mddev->major_version == 0 &&
7156                     mddev->minor_version > 90)
7157                         rdev->recovery_offset = reshape_offset;
7158
7159                 if (rdev->recovery_offset < reshape_offset) {
7160                         /* We need to check old and new layout */
7161                         if (!only_parity(rdev->raid_disk,
7162                                          conf->algorithm,
7163                                          conf->raid_disks,
7164                                          conf->max_degraded))
7165                                 continue;
7166                 }
7167                 if (!only_parity(rdev->raid_disk,
7168                                  conf->prev_algo,
7169                                  conf->previous_raid_disks,
7170                                  conf->max_degraded))
7171                         continue;
7172                 dirty_parity_disks++;
7173         }
7174
7175         /*
7176          * 0 for a fully functional array, 1 or 2 for a degraded array.
7177          */
7178         mddev->degraded = raid5_calc_degraded(conf);
7179
7180         if (has_failed(conf)) {
7181                 pr_crit("md/raid:%s: not enough operational devices (%d/%d failed)\n",
7182                         mdname(mddev), mddev->degraded, conf->raid_disks);
7183                 goto abort;
7184         }
7185
7186         /* device size must be a multiple of chunk size */
7187         mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
7188         mddev->resync_max_sectors = mddev->dev_sectors;
7189
7190         if (mddev->degraded > dirty_parity_disks &&
7191             mddev->recovery_cp != MaxSector) {
7192                 if (mddev->ok_start_degraded)
7193                         pr_crit("md/raid:%s: starting dirty degraded array - data corruption possible.\n",
7194                                 mdname(mddev));
7195                 else {
7196                         pr_crit("md/raid:%s: cannot start dirty degraded array.\n",
7197                                 mdname(mddev));
7198                         goto abort;
7199                 }
7200         }
7201
7202         pr_info("md/raid:%s: raid level %d active with %d out of %d devices, algorithm %d\n",
7203                 mdname(mddev), conf->level,
7204                 mddev->raid_disks-mddev->degraded, mddev->raid_disks,
7205                 mddev->new_layout);
7206
7207         print_raid5_conf(conf);
7208
7209         if (conf->reshape_progress != MaxSector) {
7210                 conf->reshape_safe = conf->reshape_progress;
7211                 atomic_set(&conf->reshape_stripes, 0);
7212                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7213                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7214                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7215                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7216                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7217                                                         "reshape");
7218         }
7219
7220         /* Ok, everything is just fine now */
7221         if (mddev->to_remove == &raid5_attrs_group)
7222                 mddev->to_remove = NULL;
7223         else if (mddev->kobj.sd &&
7224             sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
7225                 pr_warn("raid5: failed to create sysfs attributes for %s\n",
7226                         mdname(mddev));
7227         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7228
7229         if (mddev->queue) {
7230                 int chunk_size;
7231                 bool discard_supported = true;
7232                 /* read-ahead size must cover two whole stripes, which
7233                  * is 2 * (datadisks) * chunksize where 'n' is the
7234                  * number of raid devices
7235                  */
7236                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
7237                 int stripe = data_disks *
7238                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
7239                 if (mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
7240                         mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
7241
7242                 chunk_size = mddev->chunk_sectors << 9;
7243                 blk_queue_io_min(mddev->queue, chunk_size);
7244                 blk_queue_io_opt(mddev->queue, chunk_size *
7245                                  (conf->raid_disks - conf->max_degraded));
7246                 mddev->queue->limits.raid_partial_stripes_expensive = 1;
7247                 /*
7248                  * We can only discard a whole stripe. It doesn't make sense to
7249                  * discard data disk but write parity disk
7250                  */
7251                 stripe = stripe * PAGE_SIZE;
7252                 /* Round up to power of 2, as discard handling
7253                  * currently assumes that */
7254                 while ((stripe-1) & stripe)
7255                         stripe = (stripe | (stripe-1)) + 1;
7256                 mddev->queue->limits.discard_alignment = stripe;
7257                 mddev->queue->limits.discard_granularity = stripe;
7258
7259                 /*
7260                  * We use 16-bit counter of active stripes in bi_phys_segments
7261                  * (minus one for over-loaded initialization)
7262                  */
7263                 blk_queue_max_hw_sectors(mddev->queue, 0xfffe * STRIPE_SECTORS);
7264                 blk_queue_max_discard_sectors(mddev->queue,
7265                                               0xfffe * STRIPE_SECTORS);
7266
7267                 /*
7268                  * unaligned part of discard request will be ignored, so can't
7269                  * guarantee discard_zeroes_data
7270                  */
7271                 mddev->queue->limits.discard_zeroes_data = 0;
7272
7273                 blk_queue_max_write_same_sectors(mddev->queue, 0);
7274
7275                 rdev_for_each(rdev, mddev) {
7276                         disk_stack_limits(mddev->gendisk, rdev->bdev,
7277                                           rdev->data_offset << 9);
7278                         disk_stack_limits(mddev->gendisk, rdev->bdev,
7279                                           rdev->new_data_offset << 9);
7280                         /*
7281                          * discard_zeroes_data is required, otherwise data
7282                          * could be lost. Consider a scenario: discard a stripe
7283                          * (the stripe could be inconsistent if
7284                          * discard_zeroes_data is 0); write one disk of the
7285                          * stripe (the stripe could be inconsistent again
7286                          * depending on which disks are used to calculate
7287                          * parity); the disk is broken; The stripe data of this
7288                          * disk is lost.
7289                          */
7290                         if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
7291                             !bdev_get_queue(rdev->bdev)->
7292                                                 limits.discard_zeroes_data)
7293                                 discard_supported = false;
7294                         /* Unfortunately, discard_zeroes_data is not currently
7295                          * a guarantee - just a hint.  So we only allow DISCARD
7296                          * if the sysadmin has confirmed that only safe devices
7297                          * are in use by setting a module parameter.
7298                          */
7299                         if (!devices_handle_discard_safely) {
7300                                 if (discard_supported) {
7301                                         pr_info("md/raid456: discard support disabled due to uncertainty.\n");
7302                                         pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
7303                                 }
7304                                 discard_supported = false;
7305                         }
7306                 }
7307
7308                 if (discard_supported &&
7309                     mddev->queue->limits.max_discard_sectors >= (stripe >> 9) &&
7310                     mddev->queue->limits.discard_granularity >= stripe)
7311                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
7312                                                 mddev->queue);
7313                 else
7314                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
7315                                                 mddev->queue);
7316
7317                 blk_queue_max_hw_sectors(mddev->queue, UINT_MAX);
7318         }
7319
7320         if (journal_dev) {
7321                 char b[BDEVNAME_SIZE];
7322
7323                 pr_debug("md/raid:%s: using device %s as journal\n",
7324                          mdname(mddev), bdevname(journal_dev->bdev, b));
7325                 if (r5l_init_log(conf, journal_dev))
7326                         goto abort;
7327         }
7328
7329         return 0;
7330 abort:
7331         md_unregister_thread(&mddev->thread);
7332         print_raid5_conf(conf);
7333         free_conf(conf);
7334         mddev->private = NULL;
7335         pr_warn("md/raid:%s: failed to run raid set.\n", mdname(mddev));
7336         return -EIO;
7337 }
7338
7339 static void raid5_free(struct mddev *mddev, void *priv)
7340 {
7341         struct r5conf *conf = priv;
7342
7343         free_conf(conf);
7344         mddev->to_remove = &raid5_attrs_group;
7345 }
7346
7347 static void raid5_status(struct seq_file *seq, struct mddev *mddev)
7348 {
7349         struct r5conf *conf = mddev->private;
7350         int i;
7351
7352         seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
7353                 conf->chunk_sectors / 2, mddev->layout);
7354         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
7355         rcu_read_lock();
7356         for (i = 0; i < conf->raid_disks; i++) {
7357                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
7358                 seq_printf (seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
7359         }
7360         rcu_read_unlock();
7361         seq_printf (seq, "]");
7362 }
7363
7364 static void print_raid5_conf (struct r5conf *conf)
7365 {
7366         int i;
7367         struct disk_info *tmp;
7368
7369         pr_debug("RAID conf printout:\n");
7370         if (!conf) {
7371                 pr_debug("(conf==NULL)\n");
7372                 return;
7373         }
7374         pr_debug(" --- level:%d rd:%d wd:%d\n", conf->level,
7375                conf->raid_disks,
7376                conf->raid_disks - conf->mddev->degraded);
7377
7378         for (i = 0; i < conf->raid_disks; i++) {
7379                 char b[BDEVNAME_SIZE];
7380                 tmp = conf->disks + i;
7381                 if (tmp->rdev)
7382                         pr_debug(" disk %d, o:%d, dev:%s\n",
7383                                i, !test_bit(Faulty, &tmp->rdev->flags),
7384                                bdevname(tmp->rdev->bdev, b));
7385         }
7386 }
7387
7388 static int raid5_spare_active(struct mddev *mddev)
7389 {
7390         int i;
7391         struct r5conf *conf = mddev->private;
7392         struct disk_info *tmp;
7393         int count = 0;
7394         unsigned long flags;
7395
7396         for (i = 0; i < conf->raid_disks; i++) {
7397                 tmp = conf->disks + i;
7398                 if (tmp->replacement
7399                     && tmp->replacement->recovery_offset == MaxSector
7400                     && !test_bit(Faulty, &tmp->replacement->flags)
7401                     && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
7402                         /* Replacement has just become active. */
7403                         if (!tmp->rdev
7404                             || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
7405                                 count++;
7406                         if (tmp->rdev) {
7407                                 /* Replaced device not technically faulty,
7408                                  * but we need to be sure it gets removed
7409                                  * and never re-added.
7410                                  */
7411                                 set_bit(Faulty, &tmp->rdev->flags);
7412                                 sysfs_notify_dirent_safe(
7413                                         tmp->rdev->sysfs_state);
7414                         }
7415                         sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
7416                 } else if (tmp->rdev
7417                     && tmp->rdev->recovery_offset == MaxSector
7418                     && !test_bit(Faulty, &tmp->rdev->flags)
7419                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
7420                         count++;
7421                         sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
7422                 }
7423         }
7424         spin_lock_irqsave(&conf->device_lock, flags);
7425         mddev->degraded = raid5_calc_degraded(conf);
7426         spin_unlock_irqrestore(&conf->device_lock, flags);
7427         print_raid5_conf(conf);
7428         return count;
7429 }
7430
7431 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
7432 {
7433         struct r5conf *conf = mddev->private;
7434         int err = 0;
7435         int number = rdev->raid_disk;
7436         struct md_rdev **rdevp;
7437         struct disk_info *p = conf->disks + number;
7438
7439         print_raid5_conf(conf);
7440         if (test_bit(Journal, &rdev->flags) && conf->log) {
7441                 struct r5l_log *log;
7442                 /*
7443                  * we can't wait pending write here, as this is called in
7444                  * raid5d, wait will deadlock.
7445                  */
7446                 if (atomic_read(&mddev->writes_pending))
7447                         return -EBUSY;
7448                 log = conf->log;
7449                 conf->log = NULL;
7450                 synchronize_rcu();
7451                 r5l_exit_log(log);
7452                 return 0;
7453         }
7454         if (rdev == p->rdev)
7455                 rdevp = &p->rdev;
7456         else if (rdev == p->replacement)
7457                 rdevp = &p->replacement;
7458         else
7459                 return 0;
7460
7461         if (number >= conf->raid_disks &&
7462             conf->reshape_progress == MaxSector)
7463                 clear_bit(In_sync, &rdev->flags);
7464
7465         if (test_bit(In_sync, &rdev->flags) ||
7466             atomic_read(&rdev->nr_pending)) {
7467                 err = -EBUSY;
7468                 goto abort;
7469         }
7470         /* Only remove non-faulty devices if recovery
7471          * isn't possible.
7472          */
7473         if (!test_bit(Faulty, &rdev->flags) &&
7474             mddev->recovery_disabled != conf->recovery_disabled &&
7475             !has_failed(conf) &&
7476             (!p->replacement || p->replacement == rdev) &&
7477             number < conf->raid_disks) {
7478                 err = -EBUSY;
7479                 goto abort;
7480         }
7481         *rdevp = NULL;
7482         if (!test_bit(RemoveSynchronized, &rdev->flags)) {
7483                 synchronize_rcu();
7484                 if (atomic_read(&rdev->nr_pending)) {
7485                         /* lost the race, try later */
7486                         err = -EBUSY;
7487                         *rdevp = rdev;
7488                 }
7489         }
7490         if (p->replacement) {
7491                 /* We must have just cleared 'rdev' */
7492                 p->rdev = p->replacement;
7493                 clear_bit(Replacement, &p->replacement->flags);
7494                 smp_mb(); /* Make sure other CPUs may see both as identical
7495                            * but will never see neither - if they are careful
7496                            */
7497                 p->replacement = NULL;
7498                 clear_bit(WantReplacement, &rdev->flags);
7499         } else
7500                 /* We might have just removed the Replacement as faulty-
7501                  * clear the bit just in case
7502                  */
7503                 clear_bit(WantReplacement, &rdev->flags);
7504 abort:
7505
7506         print_raid5_conf(conf);
7507         return err;
7508 }
7509
7510 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
7511 {
7512         struct r5conf *conf = mddev->private;
7513         int err = -EEXIST;
7514         int disk;
7515         struct disk_info *p;
7516         int first = 0;
7517         int last = conf->raid_disks - 1;
7518
7519         if (test_bit(Journal, &rdev->flags)) {
7520                 char b[BDEVNAME_SIZE];
7521                 if (conf->log)
7522                         return -EBUSY;
7523
7524                 rdev->raid_disk = 0;
7525                 /*
7526                  * The array is in readonly mode if journal is missing, so no
7527                  * write requests running. We should be safe
7528                  */
7529                 r5l_init_log(conf, rdev);
7530                 pr_debug("md/raid:%s: using device %s as journal\n",
7531                          mdname(mddev), bdevname(rdev->bdev, b));
7532                 return 0;
7533         }
7534         if (mddev->recovery_disabled == conf->recovery_disabled)
7535                 return -EBUSY;
7536
7537         if (rdev->saved_raid_disk < 0 && has_failed(conf))
7538                 /* no point adding a device */
7539                 return -EINVAL;
7540
7541         if (rdev->raid_disk >= 0)
7542                 first = last = rdev->raid_disk;
7543
7544         /*
7545          * find the disk ... but prefer rdev->saved_raid_disk
7546          * if possible.
7547          */
7548         if (rdev->saved_raid_disk >= 0 &&
7549             rdev->saved_raid_disk >= first &&
7550             conf->disks[rdev->saved_raid_disk].rdev == NULL)
7551                 first = rdev->saved_raid_disk;
7552
7553         for (disk = first; disk <= last; disk++) {
7554                 p = conf->disks + disk;
7555                 if (p->rdev == NULL) {
7556                         clear_bit(In_sync, &rdev->flags);
7557                         rdev->raid_disk = disk;
7558                         err = 0;
7559                         if (rdev->saved_raid_disk != disk)
7560                                 conf->fullsync = 1;
7561                         rcu_assign_pointer(p->rdev, rdev);
7562                         goto out;
7563                 }
7564         }
7565         for (disk = first; disk <= last; disk++) {
7566                 p = conf->disks + disk;
7567                 if (test_bit(WantReplacement, &p->rdev->flags) &&
7568                     p->replacement == NULL) {
7569                         clear_bit(In_sync, &rdev->flags);
7570                         set_bit(Replacement, &rdev->flags);
7571                         rdev->raid_disk = disk;
7572                         err = 0;
7573                         conf->fullsync = 1;
7574                         rcu_assign_pointer(p->replacement, rdev);
7575                         break;
7576                 }
7577         }
7578 out:
7579         print_raid5_conf(conf);
7580         return err;
7581 }
7582
7583 static int raid5_resize(struct mddev *mddev, sector_t sectors)
7584 {
7585         /* no resync is happening, and there is enough space
7586          * on all devices, so we can resize.
7587          * We need to make sure resync covers any new space.
7588          * If the array is shrinking we should possibly wait until
7589          * any io in the removed space completes, but it hardly seems
7590          * worth it.
7591          */
7592         sector_t newsize;
7593         struct r5conf *conf = mddev->private;
7594
7595         if (conf->log)
7596                 return -EINVAL;
7597         sectors &= ~((sector_t)conf->chunk_sectors - 1);
7598         newsize = raid5_size(mddev, sectors, mddev->raid_disks);
7599         if (mddev->external_size &&
7600             mddev->array_sectors > newsize)
7601                 return -EINVAL;
7602         if (mddev->bitmap) {
7603                 int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
7604                 if (ret)
7605                         return ret;
7606         }
7607         md_set_array_sectors(mddev, newsize);
7608         set_capacity(mddev->gendisk, mddev->array_sectors);
7609         revalidate_disk(mddev->gendisk);
7610         if (sectors > mddev->dev_sectors &&
7611             mddev->recovery_cp > mddev->dev_sectors) {
7612                 mddev->recovery_cp = mddev->dev_sectors;
7613                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
7614         }
7615         mddev->dev_sectors = sectors;
7616         mddev->resync_max_sectors = sectors;
7617         return 0;
7618 }
7619
7620 static int check_stripe_cache(struct mddev *mddev)
7621 {
7622         /* Can only proceed if there are plenty of stripe_heads.
7623          * We need a minimum of one full stripe,, and for sensible progress
7624          * it is best to have about 4 times that.
7625          * If we require 4 times, then the default 256 4K stripe_heads will
7626          * allow for chunk sizes up to 256K, which is probably OK.
7627          * If the chunk size is greater, user-space should request more
7628          * stripe_heads first.
7629          */
7630         struct r5conf *conf = mddev->private;
7631         if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
7632             > conf->min_nr_stripes ||
7633             ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
7634             > conf->min_nr_stripes) {
7635                 pr_warn("md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
7636                         mdname(mddev),
7637                         ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
7638                          / STRIPE_SIZE)*4);
7639                 return 0;
7640         }
7641         return 1;
7642 }
7643
7644 static int check_reshape(struct mddev *mddev)
7645 {
7646         struct r5conf *conf = mddev->private;
7647
7648         if (conf->log)
7649                 return -EINVAL;
7650         if (mddev->delta_disks == 0 &&
7651             mddev->new_layout == mddev->layout &&
7652             mddev->new_chunk_sectors == mddev->chunk_sectors)
7653                 return 0; /* nothing to do */
7654         if (has_failed(conf))
7655                 return -EINVAL;
7656         if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
7657                 /* We might be able to shrink, but the devices must
7658                  * be made bigger first.
7659                  * For raid6, 4 is the minimum size.
7660                  * Otherwise 2 is the minimum
7661                  */
7662                 int min = 2;
7663                 if (mddev->level == 6)
7664                         min = 4;
7665                 if (mddev->raid_disks + mddev->delta_disks < min)
7666                         return -EINVAL;
7667         }
7668
7669         if (!check_stripe_cache(mddev))
7670                 return -ENOSPC;
7671
7672         if (mddev->new_chunk_sectors > mddev->chunk_sectors ||
7673             mddev->delta_disks > 0)
7674                 if (resize_chunks(conf,
7675                                   conf->previous_raid_disks
7676                                   + max(0, mddev->delta_disks),
7677                                   max(mddev->new_chunk_sectors,
7678                                       mddev->chunk_sectors)
7679                             ) < 0)
7680                         return -ENOMEM;
7681         return resize_stripes(conf, (conf->previous_raid_disks
7682                                      + mddev->delta_disks));
7683 }
7684
7685 static int raid5_start_reshape(struct mddev *mddev)
7686 {
7687         struct r5conf *conf = mddev->private;
7688         struct md_rdev *rdev;
7689         int spares = 0;
7690         unsigned long flags;
7691
7692         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
7693                 return -EBUSY;
7694
7695         if (!check_stripe_cache(mddev))
7696                 return -ENOSPC;
7697
7698         if (has_failed(conf))
7699                 return -EINVAL;
7700
7701         rdev_for_each(rdev, mddev) {
7702                 if (!test_bit(In_sync, &rdev->flags)
7703                     && !test_bit(Faulty, &rdev->flags))
7704                         spares++;
7705         }
7706
7707         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
7708                 /* Not enough devices even to make a degraded array
7709                  * of that size
7710                  */
7711                 return -EINVAL;
7712
7713         /* Refuse to reduce size of the array.  Any reductions in
7714          * array size must be through explicit setting of array_size
7715          * attribute.
7716          */
7717         if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
7718             < mddev->array_sectors) {
7719                 pr_warn("md/raid:%s: array size must be reduced before number of disks\n",
7720                         mdname(mddev));
7721                 return -EINVAL;
7722         }
7723
7724         atomic_set(&conf->reshape_stripes, 0);
7725         spin_lock_irq(&conf->device_lock);
7726         write_seqcount_begin(&conf->gen_lock);
7727         conf->previous_raid_disks = conf->raid_disks;
7728         conf->raid_disks += mddev->delta_disks;
7729         conf->prev_chunk_sectors = conf->chunk_sectors;
7730         conf->chunk_sectors = mddev->new_chunk_sectors;
7731         conf->prev_algo = conf->algorithm;
7732         conf->algorithm = mddev->new_layout;
7733         conf->generation++;
7734         /* Code that selects data_offset needs to see the generation update
7735          * if reshape_progress has been set - so a memory barrier needed.
7736          */
7737         smp_mb();
7738         if (mddev->reshape_backwards)
7739                 conf->reshape_progress = raid5_size(mddev, 0, 0);
7740         else
7741                 conf->reshape_progress = 0;
7742         conf->reshape_safe = conf->reshape_progress;
7743         write_seqcount_end(&conf->gen_lock);
7744         spin_unlock_irq(&conf->device_lock);
7745
7746         /* Now make sure any requests that proceeded on the assumption
7747          * the reshape wasn't running - like Discard or Read - have
7748          * completed.
7749          */
7750         mddev_suspend(mddev);
7751         mddev_resume(mddev);
7752
7753         /* Add some new drives, as many as will fit.
7754          * We know there are enough to make the newly sized array work.
7755          * Don't add devices if we are reducing the number of
7756          * devices in the array.  This is because it is not possible
7757          * to correctly record the "partially reconstructed" state of
7758          * such devices during the reshape and confusion could result.
7759          */
7760         if (mddev->delta_disks >= 0) {
7761                 rdev_for_each(rdev, mddev)
7762                         if (rdev->raid_disk < 0 &&
7763                             !test_bit(Faulty, &rdev->flags)) {
7764                                 if (raid5_add_disk(mddev, rdev) == 0) {
7765                                         if (rdev->raid_disk
7766                                             >= conf->previous_raid_disks)
7767                                                 set_bit(In_sync, &rdev->flags);
7768                                         else
7769                                                 rdev->recovery_offset = 0;
7770
7771                                         if (sysfs_link_rdev(mddev, rdev))
7772                                                 /* Failure here is OK */;
7773                                 }
7774                         } else if (rdev->raid_disk >= conf->previous_raid_disks
7775                                    && !test_bit(Faulty, &rdev->flags)) {
7776                                 /* This is a spare that was manually added */
7777                                 set_bit(In_sync, &rdev->flags);
7778                         }
7779
7780                 /* When a reshape changes the number of devices,
7781                  * ->degraded is measured against the larger of the
7782                  * pre and post number of devices.
7783                  */
7784                 spin_lock_irqsave(&conf->device_lock, flags);
7785                 mddev->degraded = raid5_calc_degraded(conf);
7786                 spin_unlock_irqrestore(&conf->device_lock, flags);
7787         }
7788         mddev->raid_disks = conf->raid_disks;
7789         mddev->reshape_position = conf->reshape_progress;
7790         set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
7791
7792         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7793         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7794         clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
7795         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7796         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7797         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7798                                                 "reshape");
7799         if (!mddev->sync_thread) {
7800                 mddev->recovery = 0;
7801                 spin_lock_irq(&conf->device_lock);
7802                 write_seqcount_begin(&conf->gen_lock);
7803                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
7804                 mddev->new_chunk_sectors =
7805                         conf->chunk_sectors = conf->prev_chunk_sectors;
7806                 mddev->new_layout = conf->algorithm = conf->prev_algo;
7807                 rdev_for_each(rdev, mddev)
7808                         rdev->new_data_offset = rdev->data_offset;
7809                 smp_wmb();
7810                 conf->generation --;
7811                 conf->reshape_progress = MaxSector;
7812                 mddev->reshape_position = MaxSector;
7813                 write_seqcount_end(&conf->gen_lock);
7814                 spin_unlock_irq(&conf->device_lock);
7815                 return -EAGAIN;
7816         }
7817         conf->reshape_checkpoint = jiffies;
7818         md_wakeup_thread(mddev->sync_thread);
7819         md_new_event(mddev);
7820         return 0;
7821 }
7822
7823 /* This is called from the reshape thread and should make any
7824  * changes needed in 'conf'
7825  */
7826 static void end_reshape(struct r5conf *conf)
7827 {
7828
7829         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
7830                 struct md_rdev *rdev;
7831
7832                 spin_lock_irq(&conf->device_lock);
7833                 conf->previous_raid_disks = conf->raid_disks;
7834                 rdev_for_each(rdev, conf->mddev)
7835                         rdev->data_offset = rdev->new_data_offset;
7836                 smp_wmb();
7837                 conf->reshape_progress = MaxSector;
7838                 conf->mddev->reshape_position = MaxSector;
7839                 spin_unlock_irq(&conf->device_lock);
7840                 wake_up(&conf->wait_for_overlap);
7841
7842                 /* read-ahead size must cover two whole stripes, which is
7843                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
7844                  */
7845                 if (conf->mddev->queue) {
7846                         int data_disks = conf->raid_disks - conf->max_degraded;
7847                         int stripe = data_disks * ((conf->chunk_sectors << 9)
7848                                                    / PAGE_SIZE);
7849                         if (conf->mddev->queue->backing_dev_info->ra_pages < 2 * stripe)
7850                                 conf->mddev->queue->backing_dev_info->ra_pages = 2 * stripe;
7851                 }
7852         }
7853 }
7854
7855 /* This is called from the raid5d thread with mddev_lock held.
7856  * It makes config changes to the device.
7857  */
7858 static void raid5_finish_reshape(struct mddev *mddev)
7859 {
7860         struct r5conf *conf = mddev->private;
7861
7862         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
7863
7864                 if (mddev->delta_disks > 0) {
7865                         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7866                         if (mddev->queue) {
7867                                 set_capacity(mddev->gendisk, mddev->array_sectors);
7868                                 revalidate_disk(mddev->gendisk);
7869                         }
7870                 } else {
7871                         int d;
7872                         spin_lock_irq(&conf->device_lock);
7873                         mddev->degraded = raid5_calc_degraded(conf);
7874                         spin_unlock_irq(&conf->device_lock);
7875                         for (d = conf->raid_disks ;
7876                              d < conf->raid_disks - mddev->delta_disks;
7877                              d++) {
7878                                 struct md_rdev *rdev = conf->disks[d].rdev;
7879                                 if (rdev)
7880                                         clear_bit(In_sync, &rdev->flags);
7881                                 rdev = conf->disks[d].replacement;
7882                                 if (rdev)
7883                                         clear_bit(In_sync, &rdev->flags);
7884                         }
7885                 }
7886                 mddev->layout = conf->algorithm;
7887                 mddev->chunk_sectors = conf->chunk_sectors;
7888                 mddev->reshape_position = MaxSector;
7889                 mddev->delta_disks = 0;
7890                 mddev->reshape_backwards = 0;
7891         }
7892 }
7893
7894 static void raid5_quiesce(struct mddev *mddev, int state)
7895 {
7896         struct r5conf *conf = mddev->private;
7897
7898         switch(state) {
7899         case 2: /* resume for a suspend */
7900                 wake_up(&conf->wait_for_overlap);
7901                 break;
7902
7903         case 1: /* stop all writes */
7904                 lock_all_device_hash_locks_irq(conf);
7905                 /* '2' tells resync/reshape to pause so that all
7906                  * active stripes can drain
7907                  */
7908                 r5c_flush_cache(conf, INT_MAX);
7909                 conf->quiesce = 2;
7910                 wait_event_cmd(conf->wait_for_quiescent,
7911                                     atomic_read(&conf->active_stripes) == 0 &&
7912                                     atomic_read(&conf->active_aligned_reads) == 0,
7913                                     unlock_all_device_hash_locks_irq(conf),
7914                                     lock_all_device_hash_locks_irq(conf));
7915                 conf->quiesce = 1;
7916                 unlock_all_device_hash_locks_irq(conf);
7917                 /* allow reshape to continue */
7918                 wake_up(&conf->wait_for_overlap);
7919                 break;
7920
7921         case 0: /* re-enable writes */
7922                 lock_all_device_hash_locks_irq(conf);
7923                 conf->quiesce = 0;
7924                 wake_up(&conf->wait_for_quiescent);
7925                 wake_up(&conf->wait_for_overlap);
7926                 unlock_all_device_hash_locks_irq(conf);
7927                 break;
7928         }
7929         r5l_quiesce(conf->log, state);
7930 }
7931
7932 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
7933 {
7934         struct r0conf *raid0_conf = mddev->private;
7935         sector_t sectors;
7936
7937         /* for raid0 takeover only one zone is supported */
7938         if (raid0_conf->nr_strip_zones > 1) {
7939                 pr_warn("md/raid:%s: cannot takeover raid0 with more than one zone.\n",
7940                         mdname(mddev));
7941                 return ERR_PTR(-EINVAL);
7942         }
7943
7944         sectors = raid0_conf->strip_zone[0].zone_end;
7945         sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
7946         mddev->dev_sectors = sectors;
7947         mddev->new_level = level;
7948         mddev->new_layout = ALGORITHM_PARITY_N;
7949         mddev->new_chunk_sectors = mddev->chunk_sectors;
7950         mddev->raid_disks += 1;
7951         mddev->delta_disks = 1;
7952         /* make sure it will be not marked as dirty */
7953         mddev->recovery_cp = MaxSector;
7954
7955         return setup_conf(mddev);
7956 }
7957
7958 static void *raid5_takeover_raid1(struct mddev *mddev)
7959 {
7960         int chunksect;
7961         void *ret;
7962
7963         if (mddev->raid_disks != 2 ||
7964             mddev->degraded > 1)
7965                 return ERR_PTR(-EINVAL);
7966
7967         /* Should check if there are write-behind devices? */
7968
7969         chunksect = 64*2; /* 64K by default */
7970
7971         /* The array must be an exact multiple of chunksize */
7972         while (chunksect && (mddev->array_sectors & (chunksect-1)))
7973                 chunksect >>= 1;
7974
7975         if ((chunksect<<9) < STRIPE_SIZE)
7976                 /* array size does not allow a suitable chunk size */
7977                 return ERR_PTR(-EINVAL);
7978
7979         mddev->new_level = 5;
7980         mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
7981         mddev->new_chunk_sectors = chunksect;
7982
7983         ret = setup_conf(mddev);
7984         if (!IS_ERR(ret))
7985                 mddev_clear_unsupported_flags(mddev,
7986                         UNSUPPORTED_MDDEV_FLAGS);
7987         return ret;
7988 }
7989
7990 static void *raid5_takeover_raid6(struct mddev *mddev)
7991 {
7992         int new_layout;
7993
7994         switch (mddev->layout) {
7995         case ALGORITHM_LEFT_ASYMMETRIC_6:
7996                 new_layout = ALGORITHM_LEFT_ASYMMETRIC;
7997                 break;
7998         case ALGORITHM_RIGHT_ASYMMETRIC_6:
7999                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
8000                 break;
8001         case ALGORITHM_LEFT_SYMMETRIC_6:
8002                 new_layout = ALGORITHM_LEFT_SYMMETRIC;
8003                 break;
8004         case ALGORITHM_RIGHT_SYMMETRIC_6:
8005                 new_layout = ALGORITHM_RIGHT_SYMMETRIC;
8006                 break;
8007         case ALGORITHM_PARITY_0_6:
8008                 new_layout = ALGORITHM_PARITY_0;
8009                 break;
8010         case ALGORITHM_PARITY_N:
8011                 new_layout = ALGORITHM_PARITY_N;
8012                 break;
8013         default:
8014                 return ERR_PTR(-EINVAL);
8015         }
8016         mddev->new_level = 5;
8017         mddev->new_layout = new_layout;
8018         mddev->delta_disks = -1;
8019         mddev->raid_disks -= 1;
8020         return setup_conf(mddev);
8021 }
8022
8023 static int raid5_check_reshape(struct mddev *mddev)
8024 {
8025         /* For a 2-drive array, the layout and chunk size can be changed
8026          * immediately as not restriping is needed.
8027          * For larger arrays we record the new value - after validation
8028          * to be used by a reshape pass.
8029          */
8030         struct r5conf *conf = mddev->private;
8031         int new_chunk = mddev->new_chunk_sectors;
8032
8033         if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
8034                 return -EINVAL;
8035         if (new_chunk > 0) {
8036                 if (!is_power_of_2(new_chunk))
8037                         return -EINVAL;
8038                 if (new_chunk < (PAGE_SIZE>>9))
8039                         return -EINVAL;
8040                 if (mddev->array_sectors & (new_chunk-1))
8041                         /* not factor of array size */
8042                         return -EINVAL;
8043         }
8044
8045         /* They look valid */
8046
8047         if (mddev->raid_disks == 2) {
8048                 /* can make the change immediately */
8049                 if (mddev->new_layout >= 0) {
8050                         conf->algorithm = mddev->new_layout;
8051                         mddev->layout = mddev->new_layout;
8052                 }
8053                 if (new_chunk > 0) {
8054                         conf->chunk_sectors = new_chunk ;
8055                         mddev->chunk_sectors = new_chunk;
8056                 }
8057                 set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
8058                 md_wakeup_thread(mddev->thread);
8059         }
8060         return check_reshape(mddev);
8061 }
8062
8063 static int raid6_check_reshape(struct mddev *mddev)
8064 {
8065         int new_chunk = mddev->new_chunk_sectors;
8066
8067         if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
8068                 return -EINVAL;
8069         if (new_chunk > 0) {
8070                 if (!is_power_of_2(new_chunk))
8071                         return -EINVAL;
8072                 if (new_chunk < (PAGE_SIZE >> 9))
8073                         return -EINVAL;
8074                 if (mddev->array_sectors & (new_chunk-1))
8075                         /* not factor of array size */
8076                         return -EINVAL;
8077         }
8078
8079         /* They look valid */
8080         return check_reshape(mddev);
8081 }
8082
8083 static void *raid5_takeover(struct mddev *mddev)
8084 {
8085         /* raid5 can take over:
8086          *  raid0 - if there is only one strip zone - make it a raid4 layout
8087          *  raid1 - if there are two drives.  We need to know the chunk size
8088          *  raid4 - trivial - just use a raid4 layout.
8089          *  raid6 - Providing it is a *_6 layout
8090          */
8091         if (mddev->level == 0)
8092                 return raid45_takeover_raid0(mddev, 5);
8093         if (mddev->level == 1)
8094                 return raid5_takeover_raid1(mddev);
8095         if (mddev->level == 4) {
8096                 mddev->new_layout = ALGORITHM_PARITY_N;
8097                 mddev->new_level = 5;
8098                 return setup_conf(mddev);
8099         }
8100         if (mddev->level == 6)
8101                 return raid5_takeover_raid6(mddev);
8102
8103         return ERR_PTR(-EINVAL);
8104 }
8105
8106 static void *raid4_takeover(struct mddev *mddev)
8107 {
8108         /* raid4 can take over:
8109          *  raid0 - if there is only one strip zone
8110          *  raid5 - if layout is right
8111          */
8112         if (mddev->level == 0)
8113                 return raid45_takeover_raid0(mddev, 4);
8114         if (mddev->level == 5 &&
8115             mddev->layout == ALGORITHM_PARITY_N) {
8116                 mddev->new_layout = 0;
8117                 mddev->new_level = 4;
8118                 return setup_conf(mddev);
8119         }
8120         return ERR_PTR(-EINVAL);
8121 }
8122
8123 static struct md_personality raid5_personality;
8124
8125 static void *raid6_takeover(struct mddev *mddev)
8126 {
8127         /* Currently can only take over a raid5.  We map the
8128          * personality to an equivalent raid6 personality
8129          * with the Q block at the end.
8130          */
8131         int new_layout;
8132
8133         if (mddev->pers != &raid5_personality)
8134                 return ERR_PTR(-EINVAL);
8135         if (mddev->degraded > 1)
8136                 return ERR_PTR(-EINVAL);
8137         if (mddev->raid_disks > 253)
8138                 return ERR_PTR(-EINVAL);
8139         if (mddev->raid_disks < 3)
8140                 return ERR_PTR(-EINVAL);
8141
8142         switch (mddev->layout) {
8143         case ALGORITHM_LEFT_ASYMMETRIC:
8144                 new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
8145                 break;
8146         case ALGORITHM_RIGHT_ASYMMETRIC:
8147                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
8148                 break;
8149         case ALGORITHM_LEFT_SYMMETRIC:
8150                 new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
8151                 break;
8152         case ALGORITHM_RIGHT_SYMMETRIC:
8153                 new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
8154                 break;
8155         case ALGORITHM_PARITY_0:
8156                 new_layout = ALGORITHM_PARITY_0_6;
8157                 break;
8158         case ALGORITHM_PARITY_N:
8159                 new_layout = ALGORITHM_PARITY_N;
8160                 break;
8161         default:
8162                 return ERR_PTR(-EINVAL);
8163         }
8164         mddev->new_level = 6;
8165         mddev->new_layout = new_layout;
8166         mddev->delta_disks = 1;
8167         mddev->raid_disks += 1;
8168         return setup_conf(mddev);
8169 }
8170
8171 static struct md_personality raid6_personality =
8172 {
8173         .name           = "raid6",
8174         .level          = 6,
8175         .owner          = THIS_MODULE,
8176         .make_request   = raid5_make_request,
8177         .run            = raid5_run,
8178         .free           = raid5_free,
8179         .status         = raid5_status,
8180         .error_handler  = raid5_error,
8181         .hot_add_disk   = raid5_add_disk,
8182         .hot_remove_disk= raid5_remove_disk,
8183         .spare_active   = raid5_spare_active,
8184         .sync_request   = raid5_sync_request,
8185         .resize         = raid5_resize,
8186         .size           = raid5_size,
8187         .check_reshape  = raid6_check_reshape,
8188         .start_reshape  = raid5_start_reshape,
8189         .finish_reshape = raid5_finish_reshape,
8190         .quiesce        = raid5_quiesce,
8191         .takeover       = raid6_takeover,
8192         .congested      = raid5_congested,
8193 };
8194 static struct md_personality raid5_personality =
8195 {
8196         .name           = "raid5",
8197         .level          = 5,
8198         .owner          = THIS_MODULE,
8199         .make_request   = raid5_make_request,
8200         .run            = raid5_run,
8201         .free           = raid5_free,
8202         .status         = raid5_status,
8203         .error_handler  = raid5_error,
8204         .hot_add_disk   = raid5_add_disk,
8205         .hot_remove_disk= raid5_remove_disk,
8206         .spare_active   = raid5_spare_active,
8207         .sync_request   = raid5_sync_request,
8208         .resize         = raid5_resize,
8209         .size           = raid5_size,
8210         .check_reshape  = raid5_check_reshape,
8211         .start_reshape  = raid5_start_reshape,
8212         .finish_reshape = raid5_finish_reshape,
8213         .quiesce        = raid5_quiesce,
8214         .takeover       = raid5_takeover,
8215         .congested      = raid5_congested,
8216 };
8217
8218 static struct md_personality raid4_personality =
8219 {
8220         .name           = "raid4",
8221         .level          = 4,
8222         .owner          = THIS_MODULE,
8223         .make_request   = raid5_make_request,
8224         .run            = raid5_run,
8225         .free           = raid5_free,
8226         .status         = raid5_status,
8227         .error_handler  = raid5_error,
8228         .hot_add_disk   = raid5_add_disk,
8229         .hot_remove_disk= raid5_remove_disk,
8230         .spare_active   = raid5_spare_active,
8231         .sync_request   = raid5_sync_request,
8232         .resize         = raid5_resize,
8233         .size           = raid5_size,
8234         .check_reshape  = raid5_check_reshape,
8235         .start_reshape  = raid5_start_reshape,
8236         .finish_reshape = raid5_finish_reshape,
8237         .quiesce        = raid5_quiesce,
8238         .takeover       = raid4_takeover,
8239         .congested      = raid5_congested,
8240 };
8241
8242 static int __init raid5_init(void)
8243 {
8244         int ret;
8245
8246         raid5_wq = alloc_workqueue("raid5wq",
8247                 WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
8248         if (!raid5_wq)
8249                 return -ENOMEM;
8250
8251         ret = cpuhp_setup_state_multi(CPUHP_MD_RAID5_PREPARE,
8252                                       "md/raid5:prepare",
8253                                       raid456_cpu_up_prepare,
8254                                       raid456_cpu_dead);
8255         if (ret) {
8256                 destroy_workqueue(raid5_wq);
8257                 return ret;
8258         }
8259         register_md_personality(&raid6_personality);
8260         register_md_personality(&raid5_personality);
8261         register_md_personality(&raid4_personality);
8262         return 0;
8263 }
8264
8265 static void raid5_exit(void)
8266 {
8267         unregister_md_personality(&raid6_personality);
8268         unregister_md_personality(&raid5_personality);
8269         unregister_md_personality(&raid4_personality);
8270         cpuhp_remove_multi_state(CPUHP_MD_RAID5_PREPARE);
8271         destroy_workqueue(raid5_wq);
8272 }
8273
8274 module_init(raid5_init);
8275 module_exit(raid5_exit);
8276 MODULE_LICENSE("GPL");
8277 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
8278 MODULE_ALIAS("md-personality-4"); /* RAID5 */
8279 MODULE_ALIAS("md-raid5");
8280 MODULE_ALIAS("md-raid4");
8281 MODULE_ALIAS("md-level-5");
8282 MODULE_ALIAS("md-level-4");
8283 MODULE_ALIAS("md-personality-8"); /* RAID6 */
8284 MODULE_ALIAS("md-raid6");
8285 MODULE_ALIAS("md-level-6");
8286
8287 /* This used to be two separate modules, they were: */
8288 MODULE_ALIAS("raid5");
8289 MODULE_ALIAS("raid6");