drivers/md/raid10.c

   1 /*
   2  * raid10.c : Multiple Devices driver for Linux
   3  *
   4  * Copyright (C) 2000-2004 Neil Brown
   5  *
   6  * RAID-10 support for md.
   7  *
   8  * Base on code in raid1.c.  See raid1.c for further copyright information.
   9  *
  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 #include <linux/slab.h>
  22 #include <linux/delay.h>
  23 #include <linux/blkdev.h>
  24 #include <linux/seq_file.h>
  25 #include "md.h"
  26 #include "raid10.h"
  27 #include "raid0.h"
  28 #include "bitmap.h"
  29
  30 /*
  31  * RAID10 provides a combination of RAID0 and RAID1 functionality.
  32  * The layout of data is defined by
  33  *    chunk_size
  34  *    raid_disks
  35  *    near_copies (stored in low byte of layout)
  36  *    far_copies (stored in second byte of layout)
  37  *    far_offset (stored in bit 16 of layout )
  38  *
  39  * The data to be stored is divided into chunks using chunksize.
  40  * Each device is divided into far_copies sections.
  41  * In each section, chunks are laid out in a style similar to raid0, but
  42  * near_copies copies of each chunk is stored (each on a different drive).
  43  * The starting device for each section is offset near_copies from the starting
  44  * device of the previous section.
  45  * Thus they are (near_copies*far_copies) of each chunk, and each is on a different
  46  * drive.
  47  * near_copies and far_copies must be at least one, and their product is at most
  48  * raid_disks.
  49  *
  50  * If far_offset is true, then the far_copies are handled a bit differently.
  51  * The copies are still in different stripes, but instead of be very far apart
  52  * on disk, there are adjacent stripes.
  53  */
  54
  55 /*
  56  * Number of guaranteed r10bios in case of extreme VM load:
  57  */
  58 #define NR_RAID10_BIOS 256
  59
  60 static void allow_barrier(conf_t *conf);
  61 static void lower_barrier(conf_t *conf);
  62
  63 static void * r10bio_pool_alloc(gfp_t gfp_flags, void *data)
  64 {
  65         conf_t *conf = data;
  66         int size = offsetof(struct r10bio_s, devs[conf->copies]);
  67
  68         /* allocate a r10bio with room for raid_disks entries in the bios array */
  69         return kzalloc(size, gfp_flags);
  70 }
  71
  72 static void r10bio_pool_free(void *r10_bio, void *data)
  73 {
  74         kfree(r10_bio);
  75 }
  76
  77 /* Maximum size of each resync request */
  78 #define RESYNC_BLOCK_SIZE (64*1024)
  79 #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
  80 /* amount of memory to reserve for resync requests */
  81 #define RESYNC_WINDOW (1024*1024)
  82 /* maximum number of concurrent requests, memory permitting */
  83 #define RESYNC_DEPTH (32*1024*1024/RESYNC_BLOCK_SIZE)
  84
  85 /*
  86  * When performing a resync, we need to read and compare, so
  87  * we need as many pages are there are copies.
  88  * When performing a recovery, we need 2 bios, one for read,
  89  * one for write (we recover only one drive per r10buf)
  90  *
  91  */
  92 static void * r10buf_pool_alloc(gfp_t gfp_flags, void *data)
  93 {
  94         conf_t *conf = data;
  95         struct page *page;
  96         r10bio_t *r10_bio;
  97         struct bio *bio;
  98         int i, j;
  99         int nalloc;
 100
 101         r10_bio = r10bio_pool_alloc(gfp_flags, conf);
 102         if (!r10_bio)
 103                 return NULL;
 104
 105         if (test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
 106                 nalloc = conf->copies; /* resync */
 107         else
 108                 nalloc = 2; /* recovery */
 109
 110         /*
 111          * Allocate bios.
 112          */
 113         for (j = nalloc ; j-- ; ) {
 114                 bio = bio_kmalloc(gfp_flags, RESYNC_PAGES);
 115                 if (!bio)
 116                         goto out_free_bio;
 117                 r10_bio->devs[j].bio = bio;
 118         }
 119         /*
 120          * Allocate RESYNC_PAGES data pages and attach them
 121          * where needed.
 122          */
 123         for (j = 0 ; j < nalloc; j++) {
 124                 bio = r10_bio->devs[j].bio;
 125                 for (i = 0; i < RESYNC_PAGES; i++) {
 126                         page = alloc_page(gfp_flags);
 127                         if (unlikely(!page))
 128                                 goto out_free_pages;
 129
 130                         bio->bi_io_vec[i].bv_page = page;
 131                 }
 132         }
 133
 134         return r10_bio;
 135
 136 out_free_pages:
 137         for ( ; i > 0 ; i--)
 138                 safe_put_page(bio->bi_io_vec[i-1].bv_page);
 139         while (j--)
 140                 for (i = 0; i < RESYNC_PAGES ; i++)
 141                         safe_put_page(r10_bio->devs[j].bio->bi_io_vec[i].bv_page);
 142         j = -1;
 143 out_free_bio:
 144         while ( ++j < nalloc )
 145                 bio_put(r10_bio->devs[j].bio);
 146         r10bio_pool_free(r10_bio, conf);
 147         return NULL;
 148 }
 149
 150 static void r10buf_pool_free(void *__r10_bio, void *data)
 151 {
 152         int i;
 153         conf_t *conf = data;
 154         r10bio_t *r10bio = __r10_bio;
 155         int j;
 156
 157         for (j=0; j < conf->copies; j++) {
 158                 struct bio *bio = r10bio->devs[j].bio;
 159                 if (bio) {
 160                         for (i = 0; i < RESYNC_PAGES; i++) {
 161                                 safe_put_page(bio->bi_io_vec[i].bv_page);
 162                                 bio->bi_io_vec[i].bv_page = NULL;
 163                         }
 164                         bio_put(bio);
 165                 }
 166         }
 167         r10bio_pool_free(r10bio, conf);
 168 }
 169
 170 static void put_all_bios(conf_t *conf, r10bio_t *r10_bio)
 171 {
 172         int i;
 173
 174         for (i = 0; i < conf->copies; i++) {
 175                 struct bio **bio = & r10_bio->devs[i].bio;
 176                 if (*bio && *bio != IO_BLOCKED)
 177                         bio_put(*bio);
 178                 *bio = NULL;
 179         }
 180 }
 181
 182 static void free_r10bio(r10bio_t *r10_bio)
 183 {
 184         conf_t *conf = r10_bio->mddev->private;
 185
 186         /*
 187          * Wake up any possible resync thread that waits for the device
 188          * to go idle.
 189          */
 190         allow_barrier(conf);
 191
 192         put_all_bios(conf, r10_bio);
 193         mempool_free(r10_bio, conf->r10bio_pool);
 194 }
 195
 196 static void put_buf(r10bio_t *r10_bio)
 197 {
 198         conf_t *conf = r10_bio->mddev->private;
 199
 200         mempool_free(r10_bio, conf->r10buf_pool);
 201
 202         lower_barrier(conf);
 203 }
 204
 205 static void reschedule_retry(r10bio_t *r10_bio)
 206 {
 207         unsigned long flags;
 208         mddev_t *mddev = r10_bio->mddev;
 209         conf_t *conf = mddev->private;
 210
 211         spin_lock_irqsave(&conf->device_lock, flags);
 212         list_add(&r10_bio->retry_list, &conf->retry_list);
 213         conf->nr_queued ++;
 214         spin_unlock_irqrestore(&conf->device_lock, flags);
 215
 216         /* wake up frozen array... */
 217         wake_up(&conf->wait_barrier);
 218
 219         md_wakeup_thread(mddev->thread);
 220 }
 221
 222 /*
 223  * raid_end_bio_io() is called when we have finished servicing a mirrored
 224  * operation and are ready to return a success/failure code to the buffer
 225  * cache layer.
 226  */
 227 static void raid_end_bio_io(r10bio_t *r10_bio)
 228 {
 229         struct bio *bio = r10_bio->master_bio;
 230
 231         bio_endio(bio,
 232                 test_bit(R10BIO_Uptodate, &r10_bio->state) ? 0 : -EIO);
 233         free_r10bio(r10_bio);
 234 }
 235
 236 /*
 237  * Update disk head position estimator based on IRQ completion info.
 238  */
 239 static inline void update_head_pos(int slot, r10bio_t *r10_bio)
 240 {
 241         conf_t *conf = r10_bio->mddev->private;
 242
 243         conf->mirrors[r10_bio->devs[slot].devnum].head_position =
 244                 r10_bio->devs[slot].addr + (r10_bio->sectors);
 245 }
 246
 247 static void raid10_end_read_request(struct bio *bio, int error)
 248 {
 249         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 250         r10bio_t *r10_bio = bio->bi_private;
 251         int slot, dev;
 252         conf_t *conf = r10_bio->mddev->private;
 253
 254
 255         slot = r10_bio->read_slot;
 256         dev = r10_bio->devs[slot].devnum;
 257         /*
 258          * this branch is our 'one mirror IO has finished' event handler:
 259          */
 260         update_head_pos(slot, r10_bio);
 261
 262         if (uptodate) {
 263                 /*
 264                  * Set R10BIO_Uptodate in our master bio, so that
 265                  * we will return a good error code to the higher
 266                  * levels even if IO on some other mirrored buffer fails.
 267                  *
 268                  * The 'master' represents the composite IO operation to
 269                  * user-side. So if something waits for IO, then it will
 270                  * wait for the 'master' bio.
 271                  */
 272                 set_bit(R10BIO_Uptodate, &r10_bio->state);
 273                 raid_end_bio_io(r10_bio);
 274         } else {
 275                 /*
 276                  * oops, read error:
 277                  */
 278                 char b[BDEVNAME_SIZE];
 279                 if (printk_ratelimit())
 280                         printk(KERN_ERR "md/raid10:%s: %s: rescheduling sector %llu\n",
 281                                mdname(conf->mddev),
 282                                bdevname(conf->mirrors[dev].rdev->bdev,b), (unsigned long long)r10_bio->sector);
 283                 reschedule_retry(r10_bio);
 284         }
 285
 286         rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
 287 }
 288
 289 static void raid10_end_write_request(struct bio *bio, int error)
 290 {
 291         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 292         r10bio_t *r10_bio = bio->bi_private;
 293         int slot, dev;
 294         conf_t *conf = r10_bio->mddev->private;
 295
 296         for (slot = 0; slot < conf->copies; slot++)
 297                 if (r10_bio->devs[slot].bio == bio)
 298                         break;
 299         dev = r10_bio->devs[slot].devnum;
 300
 301         /*
 302          * this branch is our 'one mirror IO has finished' event handler:
 303          */
 304         if (!uptodate) {
 305                 md_error(r10_bio->mddev, conf->mirrors[dev].rdev);
 306                 /* an I/O failed, we can't clear the bitmap */
 307                 set_bit(R10BIO_Degraded, &r10_bio->state);
 308         } else
 309                 /*
 310                  * Set R10BIO_Uptodate in our master bio, so that
 311                  * we will return a good error code for to the higher
 312                  * levels even if IO on some other mirrored buffer fails.
 313                  *
 314                  * The 'master' represents the composite IO operation to
 315                  * user-side. So if something waits for IO, then it will
 316                  * wait for the 'master' bio.
 317                  */
 318                 set_bit(R10BIO_Uptodate, &r10_bio->state);
 319
 320         update_head_pos(slot, r10_bio);
 321
 322         /*
 323          *
 324          * Let's see if all mirrored write operations have finished
 325          * already.
 326          */
 327         if (atomic_dec_and_test(&r10_bio->remaining)) {
 328                 /* clear the bitmap if all writes complete successfully */
 329                 bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
 330                                 r10_bio->sectors,
 331                                 !test_bit(R10BIO_Degraded, &r10_bio->state),
 332                                 0);
 333                 md_write_end(r10_bio->mddev);
 334                 raid_end_bio_io(r10_bio);
 335         }
 336
 337         rdev_dec_pending(conf->mirrors[dev].rdev, conf->mddev);
 338 }
 339
 340
 341 /*
 342  * RAID10 layout manager
 343  * As well as the chunksize and raid_disks count, there are two
 344  * parameters: near_copies and far_copies.
 345  * near_copies * far_copies must be <= raid_disks.
 346  * Normally one of these will be 1.
 347  * If both are 1, we get raid0.
 348  * If near_copies == raid_disks, we get raid1.
 349  *
 350  * Chunks are laid out in raid0 style with near_copies copies of the
 351  * first chunk, followed by near_copies copies of the next chunk and
 352  * so on.
 353  * If far_copies > 1, then after 1/far_copies of the array has been assigned
 354  * as described above, we start again with a device offset of near_copies.
 355  * So we effectively have another copy of the whole array further down all
 356  * the drives, but with blocks on different drives.
 357  * With this layout, and block is never stored twice on the one device.
 358  *
 359  * raid10_find_phys finds the sector offset of a given virtual sector
 360  * on each device that it is on.
 361  *
 362  * raid10_find_virt does the reverse mapping, from a device and a
 363  * sector offset to a virtual address
 364  */
 365
 366 static void raid10_find_phys(conf_t *conf, r10bio_t *r10bio)
 367 {
 368         int n,f;
 369         sector_t sector;
 370         sector_t chunk;
 371         sector_t stripe;
 372         int dev;
 373
 374         int slot = 0;
 375
 376         /* now calculate first sector/dev */
 377         chunk = r10bio->sector >> conf->chunk_shift;
 378         sector = r10bio->sector & conf->chunk_mask;
 379
 380         chunk *= conf->near_copies;
 381         stripe = chunk;
 382         dev = sector_div(stripe, conf->raid_disks);
 383         if (conf->far_offset)
 384                 stripe *= conf->far_copies;
 385
 386         sector += stripe << conf->chunk_shift;
 387
 388         /* and calculate all the others */
 389         for (n=0; n < conf->near_copies; n++) {
 390                 int d = dev;
 391                 sector_t s = sector;
 392                 r10bio->devs[slot].addr = sector;
 393                 r10bio->devs[slot].devnum = d;
 394                 slot++;
 395
 396                 for (f = 1; f < conf->far_copies; f++) {
 397                         d += conf->near_copies;
 398                         if (d >= conf->raid_disks)
 399                                 d -= conf->raid_disks;
 400                         s += conf->stride;
 401                         r10bio->devs[slot].devnum = d;
 402                         r10bio->devs[slot].addr = s;
 403                         slot++;
 404                 }
 405                 dev++;
 406                 if (dev >= conf->raid_disks) {
 407                         dev = 0;
 408                         sector += (conf->chunk_mask + 1);
 409                 }
 410         }
 411         BUG_ON(slot != conf->copies);
 412 }
 413
 414 static sector_t raid10_find_virt(conf_t *conf, sector_t sector, int dev)
 415 {
 416         sector_t offset, chunk, vchunk;
 417
 418         offset = sector & conf->chunk_mask;
 419         if (conf->far_offset) {
 420                 int fc;
 421                 chunk = sector >> conf->chunk_shift;
 422                 fc = sector_div(chunk, conf->far_copies);
 423                 dev -= fc * conf->near_copies;
 424                 if (dev < 0)
 425                         dev += conf->raid_disks;
 426         } else {
 427                 while (sector >= conf->stride) {
 428                         sector -= conf->stride;
 429                         if (dev < conf->near_copies)
 430                                 dev += conf->raid_disks - conf->near_copies;
 431                         else
 432                                 dev -= conf->near_copies;
 433                 }
 434                 chunk = sector >> conf->chunk_shift;
 435         }
 436         vchunk = chunk * conf->raid_disks + dev;
 437         sector_div(vchunk, conf->near_copies);
 438         return (vchunk << conf->chunk_shift) + offset;
 439 }
 440
 441 /**
 442  *      raid10_mergeable_bvec -- tell bio layer if a two requests can be merged
 443  *      @q: request queue
 444  *      @bvm: properties of new bio
 445  *      @biovec: the request that could be merged to it.
 446  *
 447  *      Return amount of bytes we can accept at this offset
 448  *      If near_copies == raid_disk, there are no striping issues,
 449  *      but in that case, the function isn't called at all.
 450  */
 451 static int raid10_mergeable_bvec(struct request_queue *q,
 452                                  struct bvec_merge_data *bvm,
 453                                  struct bio_vec *biovec)
 454 {
 455         mddev_t *mddev = q->queuedata;
 456         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
 457         int max;
 458         unsigned int chunk_sectors = mddev->chunk_sectors;
 459         unsigned int bio_sectors = bvm->bi_size >> 9;
 460
 461         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
 462         if (max < 0) max = 0; /* bio_add cannot handle a negative return */
 463         if (max <= biovec->bv_len && bio_sectors == 0)
 464                 return biovec->bv_len;
 465         else
 466                 return max;
 467 }
 468
 469 /*
 470  * This routine returns the disk from which the requested read should
 471  * be done. There is a per-array 'next expected sequential IO' sector
 472  * number - if this matches on the next IO then we use the last disk.
 473  * There is also a per-disk 'last know head position' sector that is
 474  * maintained from IRQ contexts, both the normal and the resync IO
 475  * completion handlers update this position correctly. If there is no
 476  * perfect sequential match then we pick the disk whose head is closest.
 477  *
 478  * If there are 2 mirrors in the same 2 devices, performance degrades
 479  * because position is mirror, not device based.
 480  *
 481  * The rdev for the device selected will have nr_pending incremented.
 482  */
 483
 484 /*
 485  * FIXME: possibly should rethink readbalancing and do it differently
 486  * depending on near_copies / far_copies geometry.
 487  */
 488 static int read_balance(conf_t *conf, r10bio_t *r10_bio)
 489 {
 490         const sector_t this_sector = r10_bio->sector;
 491         int disk, slot;
 492         const int sectors = r10_bio->sectors;
 493         sector_t new_distance, best_dist;
 494         mdk_rdev_t *rdev;
 495         int do_balance;
 496         int best_slot;
 497
 498         raid10_find_phys(conf, r10_bio);
 499         rcu_read_lock();
 500 retry:
 501         best_slot = -1;
 502         best_dist = MaxSector;
 503         do_balance = 1;
 504         /*
 505          * Check if we can balance. We can balance on the whole
 506          * device if no resync is going on (recovery is ok), or below
 507          * the resync window. We take the first readable disk when
 508          * above the resync window.
 509          */
 510         if (conf->mddev->recovery_cp < MaxSector
 511             && (this_sector + sectors >= conf->next_resync))
 512                 do_balance = 0;
 513
 514         for (slot = 0; slot < conf->copies ; slot++) {
 515                 if (r10_bio->devs[slot].bio == IO_BLOCKED)
 516                         continue;
 517                 disk = r10_bio->devs[slot].devnum;
 518                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
 519                 if (rdev == NULL)
 520                         continue;
 521                 if (!test_bit(In_sync, &rdev->flags))
 522                         continue;
 523
 524                 if (!do_balance)
 525                         break;
 526
 527                 /* This optimisation is debatable, and completely destroys
 528                  * sequential read speed for 'far copies' arrays.  So only
 529                  * keep it for 'near' arrays, and review those later.
 530                  */
 531                 if (conf->near_copies > 1 && !atomic_read(&rdev->nr_pending))
 532                         break;
 533
 534                 /* for far > 1 always use the lowest address */
 535                 if (conf->far_copies > 1)
 536                         new_distance = r10_bio->devs[slot].addr;
 537                 else
 538                         new_distance = abs(r10_bio->devs[slot].addr -
 539                                            conf->mirrors[disk].head_position);
 540                 if (new_distance < best_dist) {
 541                         best_dist = new_distance;
 542                         best_slot = slot;
 543                 }
 544         }
 545         if (slot == conf->copies)
 546                 slot = best_slot;
 547
 548         if (slot >= 0) {
 549                 disk = r10_bio->devs[slot].devnum;
 550                 rdev = rcu_dereference(conf->mirrors[disk].rdev);
 551                 if (!rdev)
 552                         goto retry;
 553                 atomic_inc(&rdev->nr_pending);
 554                 if (test_bit(Faulty, &rdev->flags)) {
 555                         /* Cannot risk returning a device that failed
 556                          * before we inc'ed nr_pending
 557                          */
 558                         rdev_dec_pending(rdev, conf->mddev);
 559                         goto retry;
 560                 }
 561                 r10_bio->read_slot = slot;
 562         } else
 563                 disk = -1;
 564         rcu_read_unlock();
 565
 566         return disk;
 567 }
 568
 569 static int raid10_congested(void *data, int bits)
 570 {
 571         mddev_t *mddev = data;
 572         conf_t *conf = mddev->private;
 573         int i, ret = 0;
 574
 575         if (mddev_congested(mddev, bits))
 576                 return 1;
 577         rcu_read_lock();
 578         for (i = 0; i < conf->raid_disks && ret == 0; i++) {
 579                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);
 580                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 581                         struct request_queue *q = bdev_get_queue(rdev->bdev);
 582
 583                         ret |= bdi_congested(&q->backing_dev_info, bits);
 584                 }
 585         }
 586         rcu_read_unlock();
 587         return ret;
 588 }
 589
 590 static void flush_pending_writes(conf_t *conf)
 591 {
 592         /* Any writes that have been queued but are awaiting
 593          * bitmap updates get flushed here.
 594          */
 595         spin_lock_irq(&conf->device_lock);
 596
 597         if (conf->pending_bio_list.head) {
 598                 struct bio *bio;
 599                 bio = bio_list_get(&conf->pending_bio_list);
 600                 spin_unlock_irq(&conf->device_lock);
 601                 /* flush any pending bitmap writes to disk
 602                  * before proceeding w/ I/O */
 603                 bitmap_unplug(conf->mddev->bitmap);
 604
 605                 while (bio) { /* submit pending writes */
 606                         struct bio *next = bio->bi_next;
 607                         bio->bi_next = NULL;
 608                         generic_make_request(bio);
 609                         bio = next;
 610                 }
 611         } else
 612                 spin_unlock_irq(&conf->device_lock);
 613 }
 614
 615 /* Barriers....
 616  * Sometimes we need to suspend IO while we do something else,
 617  * either some resync/recovery, or reconfigure the array.
 618  * To do this we raise a 'barrier'.
 619  * The 'barrier' is a counter that can be raised multiple times
 620  * to count how many activities are happening which preclude
 621  * normal IO.
 622  * We can only raise the barrier if there is no pending IO.
 623  * i.e. if nr_pending == 0.
 624  * We choose only to raise the barrier if no-one is waiting for the
 625  * barrier to go down.  This means that as soon as an IO request
 626  * is ready, no other operations which require a barrier will start
 627  * until the IO request has had a chance.
 628  *
 629  * So: regular IO calls 'wait_barrier'.  When that returns there
 630  *    is no backgroup IO happening,  It must arrange to call
 631  *    allow_barrier when it has finished its IO.
 632  * backgroup IO calls must call raise_barrier.  Once that returns
 633  *    there is no normal IO happeing.  It must arrange to call
 634  *    lower_barrier when the particular background IO completes.
 635  */
 636
 637 static void raise_barrier(conf_t *conf, int force)
 638 {
 639         BUG_ON(force && !conf->barrier);
 640         spin_lock_irq(&conf->resync_lock);
 641
 642         /* Wait until no block IO is waiting (unless 'force') */
 643         wait_event_lock_irq(conf->wait_barrier, force || !conf->nr_waiting,
 644                             conf->resync_lock, );
 645
 646         /* block any new IO from starting */
 647         conf->barrier++;
 648
 649         /* Now wait for all pending IO to complete */
 650         wait_event_lock_irq(conf->wait_barrier,
 651                             !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
 652                             conf->resync_lock, );
 653
 654         spin_unlock_irq(&conf->resync_lock);
 655 }
 656
 657 static void lower_barrier(conf_t *conf)
 658 {
 659         unsigned long flags;
 660         spin_lock_irqsave(&conf->resync_lock, flags);
 661         conf->barrier--;
 662         spin_unlock_irqrestore(&conf->resync_lock, flags);
 663         wake_up(&conf->wait_barrier);
 664 }
 665
 666 static void wait_barrier(conf_t *conf)
 667 {
 668         spin_lock_irq(&conf->resync_lock);
 669         if (conf->barrier) {
 670                 conf->nr_waiting++;
 671                 wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
 672                                     conf->resync_lock,
 673                                     );
 674                 conf->nr_waiting--;
 675         }
 676         conf->nr_pending++;
 677         spin_unlock_irq(&conf->resync_lock);
 678 }
 679
 680 static void allow_barrier(conf_t *conf)
 681 {
 682         unsigned long flags;
 683         spin_lock_irqsave(&conf->resync_lock, flags);
 684         conf->nr_pending--;
 685         spin_unlock_irqrestore(&conf->resync_lock, flags);
 686         wake_up(&conf->wait_barrier);
 687 }
 688
 689 static void freeze_array(conf_t *conf)
 690 {
 691         /* stop syncio and normal IO and wait for everything to
 692          * go quiet.
 693          * We increment barrier and nr_waiting, and then
 694          * wait until nr_pending match nr_queued+1
 695          * This is called in the context of one normal IO request
 696          * that has failed. Thus any sync request that might be pending
 697          * will be blocked by nr_pending, and we need to wait for
 698          * pending IO requests to complete or be queued for re-try.
 699          * Thus the number queued (nr_queued) plus this request (1)
 700          * must match the number of pending IOs (nr_pending) before
 701          * we continue.
 702          */
 703         spin_lock_irq(&conf->resync_lock);
 704         conf->barrier++;
 705         conf->nr_waiting++;
 706         wait_event_lock_irq(conf->wait_barrier,
 707                             conf->nr_pending == conf->nr_queued+1,
 708                             conf->resync_lock,
 709                             flush_pending_writes(conf));
 710
 711         spin_unlock_irq(&conf->resync_lock);
 712 }
 713
 714 static void unfreeze_array(conf_t *conf)
 715 {
 716         /* reverse the effect of the freeze */
 717         spin_lock_irq(&conf->resync_lock);
 718         conf->barrier--;
 719         conf->nr_waiting--;
 720         wake_up(&conf->wait_barrier);
 721         spin_unlock_irq(&conf->resync_lock);
 722 }
 723
 724 static int make_request(mddev_t *mddev, struct bio * bio)
 725 {
 726         conf_t *conf = mddev->private;
 727         mirror_info_t *mirror;
 728         r10bio_t *r10_bio;
 729         struct bio *read_bio;
 730         int i;
 731         int chunk_sects = conf->chunk_mask + 1;
 732         const int rw = bio_data_dir(bio);
 733         const unsigned long do_sync = (bio->bi_rw & REQ_SYNC);
 734         const unsigned long do_fua = (bio->bi_rw & REQ_FUA);
 735         unsigned long flags;
 736         mdk_rdev_t *blocked_rdev;
 737         int plugged;
 738
 739         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
 740                 md_flush_request(mddev, bio);
 741                 return 0;
 742         }
 743
 744         /* If this request crosses a chunk boundary, we need to
 745          * split it.  This will only happen for 1 PAGE (or less) requests.
 746          */
 747         if (unlikely( (bio->bi_sector & conf->chunk_mask) + (bio->bi_size >> 9)
 748                       > chunk_sects &&
 749                     conf->near_copies < conf->raid_disks)) {
 750                 struct bio_pair *bp;
 751                 /* Sanity check -- queue functions should prevent this happening */
 752                 if (bio->bi_vcnt != 1 ||
 753                     bio->bi_idx != 0)
 754                         goto bad_map;
 755                 /* This is a one page bio that upper layers
 756                  * refuse to split for us, so we need to split it.
 757                  */
 758                 bp = bio_split(bio,
 759                                chunk_sects - (bio->bi_sector & (chunk_sects - 1)) );
 760
 761                 /* Each of these 'make_request' calls will call 'wait_barrier'.
 762                  * If the first succeeds but the second blocks due to the resync
 763                  * thread raising the barrier, we will deadlock because the
 764                  * IO to the underlying device will be queued in generic_make_request
 765                  * and will never complete, so will never reduce nr_pending.
 766                  * So increment nr_waiting here so no new raise_barriers will
 767                  * succeed, and so the second wait_barrier cannot block.
 768                  */
 769                 spin_lock_irq(&conf->resync_lock);
 770                 conf->nr_waiting++;
 771                 spin_unlock_irq(&conf->resync_lock);
 772
 773                 if (make_request(mddev, &bp->bio1))
 774                         generic_make_request(&bp->bio1);
 775                 if (make_request(mddev, &bp->bio2))
 776                         generic_make_request(&bp->bio2);
 777
 778                 spin_lock_irq(&conf->resync_lock);
 779                 conf->nr_waiting--;
 780                 wake_up(&conf->wait_barrier);
 781                 spin_unlock_irq(&conf->resync_lock);
 782
 783                 bio_pair_release(bp);
 784                 return 0;
 785         bad_map:
 786                 printk("md/raid10:%s: make_request bug: can't convert block across chunks"
 787                        " or bigger than %dk %llu %d\n", mdname(mddev), chunk_sects/2,
 788                        (unsigned long long)bio->bi_sector, bio->bi_size >> 10);
 789
 790                 bio_io_error(bio);
 791                 return 0;
 792         }
 793
 794         md_write_start(mddev, bio);
 795
 796         /*
 797          * Register the new request and wait if the reconstruction
 798          * thread has put up a bar for new requests.
 799          * Continue immediately if no resync is active currently.
 800          */
 801         wait_barrier(conf);
 802
 803         r10_bio = mempool_alloc(conf->r10bio_pool, GFP_NOIO);
 804
 805         r10_bio->master_bio = bio;
 806         r10_bio->sectors = bio->bi_size >> 9;
 807
 808         r10_bio->mddev = mddev;
 809         r10_bio->sector = bio->bi_sector;
 810         r10_bio->state = 0;
 811
 812         if (rw == READ) {
 813                 /*
 814                  * read balancing logic:
 815                  */
 816                 int disk = read_balance(conf, r10_bio);
 817                 int slot = r10_bio->read_slot;
 818                 if (disk < 0) {
 819                         raid_end_bio_io(r10_bio);
 820                         return 0;
 821                 }
 822                 mirror = conf->mirrors + disk;
 823
 824                 read_bio = bio_clone_mddev(bio, GFP_NOIO, mddev);
 825
 826                 r10_bio->devs[slot].bio = read_bio;
 827
 828                 read_bio->bi_sector = r10_bio->devs[slot].addr +
 829                         mirror->rdev->data_offset;
 830                 read_bio->bi_bdev = mirror->rdev->bdev;
 831                 read_bio->bi_end_io = raid10_end_read_request;
 832                 read_bio->bi_rw = READ | do_sync;
 833                 read_bio->bi_private = r10_bio;
 834
 835                 generic_make_request(read_bio);
 836                 return 0;
 837         }
 838
 839         /*
 840          * WRITE:
 841          */
 842         /* first select target devices under rcu_lock and
 843          * inc refcount on their rdev.  Record them by setting
 844          * bios[x] to bio
 845          */
 846         plugged = mddev_check_plugged(mddev);
 847
 848         raid10_find_phys(conf, r10_bio);
 849  retry_write:
 850         blocked_rdev = NULL;
 851         rcu_read_lock();
 852         for (i = 0;  i < conf->copies; i++) {
 853                 int d = r10_bio->devs[i].devnum;
 854                 mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[d].rdev);
 855                 if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
 856                         atomic_inc(&rdev->nr_pending);
 857                         blocked_rdev = rdev;
 858                         break;
 859                 }
 860                 if (rdev && !test_bit(Faulty, &rdev->flags)) {
 861                         atomic_inc(&rdev->nr_pending);
 862                         r10_bio->devs[i].bio = bio;
 863                 } else {
 864                         r10_bio->devs[i].bio = NULL;
 865                         set_bit(R10BIO_Degraded, &r10_bio->state);
 866                 }
 867         }
 868         rcu_read_unlock();
 869
 870         if (unlikely(blocked_rdev)) {
 871                 /* Have to wait for this device to get unblocked, then retry */
 872                 int j;
 873                 int d;
 874
 875                 for (j = 0; j < i; j++)
 876                         if (r10_bio->devs[j].bio) {
 877                                 d = r10_bio->devs[j].devnum;
 878                                 rdev_dec_pending(conf->mirrors[d].rdev, mddev);
 879                         }
 880                 allow_barrier(conf);
 881                 md_wait_for_blocked_rdev(blocked_rdev, mddev);
 882                 wait_barrier(conf);
 883                 goto retry_write;
 884         }
 885
 886         atomic_set(&r10_bio->remaining, 1);
 887         bitmap_startwrite(mddev->bitmap, bio->bi_sector, r10_bio->sectors, 0);
 888
 889         for (i = 0; i < conf->copies; i++) {
 890                 struct bio *mbio;
 891                 int d = r10_bio->devs[i].devnum;
 892                 if (!r10_bio->devs[i].bio)
 893                         continue;
 894
 895                 mbio = bio_clone_mddev(bio, GFP_NOIO, mddev);
 896                 r10_bio->devs[i].bio = mbio;
 897
 898                 mbio->bi_sector = r10_bio->devs[i].addr+
 899                         conf->mirrors[d].rdev->data_offset;
 900                 mbio->bi_bdev = conf->mirrors[d].rdev->bdev;
 901                 mbio->bi_end_io = raid10_end_write_request;
 902                 mbio->bi_rw = WRITE | do_sync | do_fua;
 903                 mbio->bi_private = r10_bio;
 904
 905                 atomic_inc(&r10_bio->remaining);
 906                 spin_lock_irqsave(&conf->device_lock, flags);
 907                 bio_list_add(&conf->pending_bio_list, mbio);
 908                 spin_unlock_irqrestore(&conf->device_lock, flags);
 909         }
 910
 911         if (atomic_dec_and_test(&r10_bio->remaining)) {
 912                 /* This matches the end of raid10_end_write_request() */
 913                 bitmap_endwrite(r10_bio->mddev->bitmap, r10_bio->sector,
 914                                 r10_bio->sectors,
 915                                 !test_bit(R10BIO_Degraded, &r10_bio->state),
 916                                 0);
 917                 md_write_end(mddev);
 918                 raid_end_bio_io(r10_bio);
 919         }
 920
 921         /* In case raid10d snuck in to freeze_array */
 922         wake_up(&conf->wait_barrier);
 923
 924         if (do_sync || !mddev->bitmap || !plugged)
 925                 md_wakeup_thread(mddev->thread);
 926         return 0;
 927 }
 928
 929 static void status(struct seq_file *seq, mddev_t *mddev)
 930 {
 931         conf_t *conf = mddev->private;
 932         int i;
 933
 934         if (conf->near_copies < conf->raid_disks)
 935                 seq_printf(seq, " %dK chunks", mddev->chunk_sectors / 2);
 936         if (conf->near_copies > 1)
 937                 seq_printf(seq, " %d near-copies", conf->near_copies);
 938         if (conf->far_copies > 1) {
 939                 if (conf->far_offset)
 940                         seq_printf(seq, " %d offset-copies", conf->far_copies);
 941                 else
 942                         seq_printf(seq, " %d far-copies", conf->far_copies);
 943         }
 944         seq_printf(seq, " [%d/%d] [", conf->raid_disks,
 945                                         conf->raid_disks - mddev->degraded);
 946         for (i = 0; i < conf->raid_disks; i++)
 947                 seq_printf(seq, "%s",
 948                               conf->mirrors[i].rdev &&
 949                               test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_");
 950         seq_printf(seq, "]");
 951 }
 952
 953 static void error(mddev_t *mddev, mdk_rdev_t *rdev)
 954 {
 955         char b[BDEVNAME_SIZE];
 956         conf_t *conf = mddev->private;
 957
 958         /*
 959          * If it is not operational, then we have already marked it as dead
 960          * else if it is the last working disks, ignore the error, let the
 961          * next level up know.
 962          * else mark the drive as failed
 963          */
 964         if (test_bit(In_sync, &rdev->flags)
 965             && conf->raid_disks-mddev->degraded == 1)
 966                 /*
 967                  * Don't fail the drive, just return an IO error.
 968                  * The test should really be more sophisticated than
 969                  * "working_disks == 1", but it isn't critical, and
 970                  * can wait until we do more sophisticated "is the drive
 971                  * really dead" tests...
 972                  */
 973                 return;
 974         if (test_and_clear_bit(In_sync, &rdev->flags)) {
 975                 unsigned long flags;
 976                 spin_lock_irqsave(&conf->device_lock, flags);
 977                 mddev->degraded++;
 978                 spin_unlock_irqrestore(&conf->device_lock, flags);
 979                 /*
 980                  * if recovery is running, make sure it aborts.
 981                  */
 982                 set_bit(MD_RECOVERY_INTR, &mddev->recovery);
 983         }
 984         set_bit(Faulty, &rdev->flags);
 985         set_bit(MD_CHANGE_DEVS, &mddev->flags);
 986         printk(KERN_ALERT
 987                "md/raid10:%s: Disk failure on %s, disabling device.\n"
 988                "md/raid10:%s: Operation continuing on %d devices.\n",
 989                mdname(mddev), bdevname(rdev->bdev, b),
 990                mdname(mddev), conf->raid_disks - mddev->degraded);
 991 }
 992
 993 static void print_conf(conf_t *conf)
 994 {
 995         int i;
 996         mirror_info_t *tmp;
 997
 998         printk(KERN_DEBUG "RAID10 conf printout:\n");
 999         if (!conf) {
1000                 printk(KERN_DEBUG "(!conf)\n");
1001                 return;
1002         }
1003         printk(KERN_DEBUG " --- wd:%d rd:%d\n", conf->raid_disks - conf->mddev->degraded,
1004                 conf->raid_disks);
1005
1006         for (i = 0; i < conf->raid_disks; i++) {
1007                 char b[BDEVNAME_SIZE];
1008                 tmp = conf->mirrors + i;
1009                 if (tmp->rdev)
1010                         printk(KERN_DEBUG " disk %d, wo:%d, o:%d, dev:%s\n",
1011                                 i, !test_bit(In_sync, &tmp->rdev->flags),
1012                                 !test_bit(Faulty, &tmp->rdev->flags),
1013                                 bdevname(tmp->rdev->bdev,b));
1014         }
1015 }
1016
1017 static void close_sync(conf_t *conf)
1018 {
1019         wait_barrier(conf);
1020         allow_barrier(conf);
1021
1022         mempool_destroy(conf->r10buf_pool);
1023         conf->r10buf_pool = NULL;
1024 }
1025
1026 /* check if there are enough drives for
1027  * every block to appear on atleast one
1028  */
1029 static int enough(conf_t *conf)
1030 {
1031         int first = 0;
1032
1033         do {
1034                 int n = conf->copies;
1035                 int cnt = 0;
1036                 while (n--) {
1037                         if (conf->mirrors[first].rdev)
1038                                 cnt++;
1039                         first = (first+1) % conf->raid_disks;
1040                 }
1041                 if (cnt == 0)
1042                         return 0;
1043         } while (first != 0);
1044         return 1;
1045 }
1046
1047 static int raid10_spare_active(mddev_t *mddev)
1048 {
1049         int i;
1050         conf_t *conf = mddev->private;
1051         mirror_info_t *tmp;
1052         int count = 0;
1053         unsigned long flags;
1054
1055         /*
1056          * Find all non-in_sync disks within the RAID10 configuration
1057          * and mark them in_sync
1058          */
1059         for (i = 0; i < conf->raid_disks; i++) {
1060                 tmp = conf->mirrors + i;
1061                 if (tmp->rdev
1062                     && !test_bit(Faulty, &tmp->rdev->flags)
1063                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
1064                         count++;
1065                         sysfs_notify_dirent(tmp->rdev->sysfs_state);
1066                 }
1067         }
1068         spin_lock_irqsave(&conf->device_lock, flags);
1069         mddev->degraded -= count;
1070         spin_unlock_irqrestore(&conf->device_lock, flags);
1071
1072         print_conf(conf);
1073         return count;
1074 }
1075
1076
1077 static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
1078 {
1079         conf_t *conf = mddev->private;
1080         int err = -EEXIST;
1081         int mirror;
1082         mirror_info_t *p;
1083         int first = 0;
1084         int last = conf->raid_disks - 1;
1085
1086         if (mddev->recovery_cp < MaxSector)
1087                 /* only hot-add to in-sync arrays, as recovery is
1088                  * very different from resync
1089                  */
1090                 return -EBUSY;
1091         if (!enough(conf))
1092                 return -EINVAL;
1093
1094         if (rdev->raid_disk >= 0)
1095                 first = last = rdev->raid_disk;
1096
1097         if (rdev->saved_raid_disk >= 0 &&
1098             rdev->saved_raid_disk >= first &&
1099             conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
1100                 mirror = rdev->saved_raid_disk;
1101         else
1102                 mirror = first;
1103         for ( ; mirror <= last ; mirror++)
1104                 if ( !(p=conf->mirrors+mirror)->rdev) {
1105
1106                         disk_stack_limits(mddev->gendisk, rdev->bdev,
1107                                           rdev->data_offset << 9);
1108                         /* as we don't honour merge_bvec_fn, we must
1109                          * never risk violating it, so limit
1110                          * ->max_segments to one lying with a single
1111                          * page, as a one page request is never in
1112                          * violation.
1113                          */
1114                         if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
1115                                 blk_queue_max_segments(mddev->queue, 1);
1116                                 blk_queue_segment_boundary(mddev->queue,
1117                                                            PAGE_CACHE_SIZE - 1);
1118                         }
1119
1120                         p->head_position = 0;
1121                         rdev->raid_disk = mirror;
1122                         err = 0;
1123                         if (rdev->saved_raid_disk != mirror)
1124                                 conf->fullsync = 1;
1125                         rcu_assign_pointer(p->rdev, rdev);
1126                         break;
1127                 }
1128
1129         md_integrity_add_rdev(rdev, mddev);
1130         print_conf(conf);
1131         return err;
1132 }
1133
1134 static int raid10_remove_disk(mddev_t *mddev, int number)
1135 {
1136         conf_t *conf = mddev->private;
1137         int err = 0;
1138         mdk_rdev_t *rdev;
1139         mirror_info_t *p = conf->mirrors+ number;
1140
1141         print_conf(conf);
1142         rdev = p->rdev;
1143         if (rdev) {
1144                 if (test_bit(In_sync, &rdev->flags) ||
1145                     atomic_read(&rdev->nr_pending)) {
1146                         err = -EBUSY;
1147                         goto abort;
1148                 }
1149                 /* Only remove faulty devices in recovery
1150                  * is not possible.
1151                  */
1152                 if (!test_bit(Faulty, &rdev->flags) &&
1153                     enough(conf)) {
1154                         err = -EBUSY;
1155                         goto abort;
1156                 }
1157                 p->rdev = NULL;
1158                 synchronize_rcu();
1159                 if (atomic_read(&rdev->nr_pending)) {
1160                         /* lost the race, try later */
1161                         err = -EBUSY;
1162                         p->rdev = rdev;
1163                         goto abort;
1164                 }
1165                 err = md_integrity_register(mddev);
1166         }
1167 abort:
1168
1169         print_conf(conf);
1170         return err;
1171 }
1172
1173
1174 static void end_sync_read(struct bio *bio, int error)
1175 {
1176         r10bio_t *r10_bio = bio->bi_private;
1177         conf_t *conf = r10_bio->mddev->private;
1178         int i,d;
1179
1180         for (i=0; i<conf->copies; i++)
1181                 if (r10_bio->devs[i].bio == bio)
1182                         break;
1183         BUG_ON(i == conf->copies);
1184         update_head_pos(i, r10_bio);
1185         d = r10_bio->devs[i].devnum;
1186
1187         if (test_bit(BIO_UPTODATE, &bio->bi_flags))
1188                 set_bit(R10BIO_Uptodate, &r10_bio->state);
1189         else {
1190                 atomic_add(r10_bio->sectors,
1191                            &conf->mirrors[d].rdev->corrected_errors);
1192                 if (!test_bit(MD_RECOVERY_SYNC, &conf->mddev->recovery))
1193                         md_error(r10_bio->mddev,
1194                                  conf->mirrors[d].rdev);
1195         }
1196
1197         /* for reconstruct, we always reschedule after a read.
1198          * for resync, only after all reads
1199          */
1200         rdev_dec_pending(conf->mirrors[d].rdev, conf->mddev);
1201         if (test_bit(R10BIO_IsRecover, &r10_bio->state) ||
1202             atomic_dec_and_test(&r10_bio->remaining)) {
1203                 /* we have read all the blocks,
1204                  * do the comparison in process context in raid10d
1205                  */
1206                 reschedule_retry(r10_bio);
1207         }
1208 }
1209
1210 static void end_sync_write(struct bio *bio, int error)
1211 {
1212         int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
1213         r10bio_t *r10_bio = bio->bi_private;
1214         mddev_t *mddev = r10_bio->mddev;
1215         conf_t *conf = mddev->private;
1216         int i,d;
1217
1218         for (i = 0; i < conf->copies; i++)
1219                 if (r10_bio->devs[i].bio == bio)
1220                         break;
1221         d = r10_bio->devs[i].devnum;
1222
1223         if (!uptodate)
1224                 md_error(mddev, conf->mirrors[d].rdev);
1225
1226         update_head_pos(i, r10_bio);
1227
1228         rdev_dec_pending(conf->mirrors[d].rdev, mddev);
1229         while (atomic_dec_and_test(&r10_bio->remaining)) {
1230                 if (r10_bio->master_bio == NULL) {
1231                         /* the primary of several recovery bios */
1232                         sector_t s = r10_bio->sectors;
1233                         put_buf(r10_bio);
1234                         md_done_sync(mddev, s, 1);
1235                         break;
1236                 } else {
1237                         r10bio_t *r10_bio2 = (r10bio_t *)r10_bio->master_bio;
1238                         put_buf(r10_bio);
1239                         r10_bio = r10_bio2;
1240                 }
1241         }
1242 }
1243
1244 /*
1245  * Note: sync and recover and handled very differently for raid10
1246  * This code is for resync.
1247  * For resync, we read through virtual addresses and read all blocks.
1248  * If there is any error, we schedule a write.  The lowest numbered
1249  * drive is authoritative.
1250  * However requests come for physical address, so we need to map.
1251  * For every physical address there are raid_disks/copies virtual addresses,
1252  * which is always are least one, but is not necessarly an integer.
1253  * This means that a physical address can span multiple chunks, so we may
1254  * have to submit multiple io requests for a single sync request.
1255  */
1256 /*
1257  * We check if all blocks are in-sync and only write to blocks that
1258  * aren't in sync
1259  */
1260 static void sync_request_write(mddev_t *mddev, r10bio_t *r10_bio)
1261 {
1262         conf_t *conf = mddev->private;
1263         int i, first;
1264         struct bio *tbio, *fbio;
1265
1266         atomic_set(&r10_bio->remaining, 1);
1267
1268         /* find the first device with a block */
1269         for (i=0; i<conf->copies; i++)
1270                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags))
1271                         break;
1272
1273         if (i == conf->copies)
1274                 goto done;
1275
1276         first = i;
1277         fbio = r10_bio->devs[i].bio;
1278
1279         /* now find blocks with errors */
1280         for (i=0 ; i < conf->copies ; i++) {
1281                 int  j, d;
1282                 int vcnt = r10_bio->sectors >> (PAGE_SHIFT-9);
1283
1284                 tbio = r10_bio->devs[i].bio;
1285
1286                 if (tbio->bi_end_io != end_sync_read)
1287                         continue;
1288                 if (i == first)
1289                         continue;
1290                 if (test_bit(BIO_UPTODATE, &r10_bio->devs[i].bio->bi_flags)) {
1291                         /* We know that the bi_io_vec layout is the same for
1292                          * both 'first' and 'i', so we just compare them.
1293                          * All vec entries are PAGE_SIZE;
1294                          */
1295                         for (j = 0; j < vcnt; j++)
1296                                 if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
1297                                            page_address(tbio->bi_io_vec[j].bv_page),
1298                                            PAGE_SIZE))
1299                                         break;
1300                         if (j == vcnt)
1301                                 continue;
1302                         mddev->resync_mismatches += r10_bio->sectors;
1303                 }
1304                 if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
1305                         /* Don't fix anything. */
1306                         continue;
1307                 /* Ok, we need to write this bio
1308                  * First we need to fixup bv_offset, bv_len and
1309                  * bi_vecs, as the read request might have corrupted these
1310                  */
1311                 tbio->bi_vcnt = vcnt;
1312                 tbio->bi_size = r10_bio->sectors << 9;
1313                 tbio->bi_idx = 0;
1314                 tbio->bi_phys_segments = 0;
1315                 tbio->bi_flags &= ~(BIO_POOL_MASK - 1);
1316                 tbio->bi_flags |= 1 << BIO_UPTODATE;
1317                 tbio->bi_next = NULL;
1318                 tbio->bi_rw = WRITE;
1319                 tbio->bi_private = r10_bio;
1320                 tbio->bi_sector = r10_bio->devs[i].addr;
1321
1322                 for (j=0; j < vcnt ; j++) {
1323                         tbio->bi_io_vec[j].bv_offset = 0;
1324                         tbio->bi_io_vec[j].bv_len = PAGE_SIZE;
1325
1326                         memcpy(page_address(tbio->bi_io_vec[j].bv_page),
1327                                page_address(fbio->bi_io_vec[j].bv_page),
1328                                PAGE_SIZE);
1329                 }
1330                 tbio->bi_end_io = end_sync_write;
1331
1332                 d = r10_bio->devs[i].devnum;
1333                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1334                 atomic_inc(&r10_bio->remaining);
1335                 md_sync_acct(conf->mirrors[d].rdev->bdev, tbio->bi_size >> 9);
1336
1337                 tbio->bi_sector += conf->mirrors[d].rdev->data_offset;
1338                 tbio->bi_bdev = conf->mirrors[d].rdev->bdev;
1339                 generic_make_request(tbio);
1340         }
1341
1342 done:
1343         if (atomic_dec_and_test(&r10_bio->remaining)) {
1344                 md_done_sync(mddev, r10_bio->sectors, 1);
1345                 put_buf(r10_bio);
1346         }
1347 }
1348
1349 /*
1350  * Now for the recovery code.
1351  * Recovery happens across physical sectors.
1352  * We recover all non-is_sync drives by finding the virtual address of
1353  * each, and then choose a working drive that also has that virt address.
1354  * There is a separate r10_bio for each non-in_sync drive.
1355  * Only the first two slots are in use. The first for reading,
1356  * The second for writing.
1357  *
1358  */
1359
1360 static void recovery_request_write(mddev_t *mddev, r10bio_t *r10_bio)
1361 {
1362         conf_t *conf = mddev->private;
1363         int i, d;
1364         struct bio *bio, *wbio;
1365
1366
1367         /* move the pages across to the second bio
1368          * and submit the write request
1369          */
1370         bio = r10_bio->devs[0].bio;
1371         wbio = r10_bio->devs[1].bio;
1372         for (i=0; i < wbio->bi_vcnt; i++) {
1373                 struct page *p = bio->bi_io_vec[i].bv_page;
1374                 bio->bi_io_vec[i].bv_page = wbio->bi_io_vec[i].bv_page;
1375                 wbio->bi_io_vec[i].bv_page = p;
1376         }
1377         d = r10_bio->devs[1].devnum;
1378
1379         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1380         md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9);
1381         if (test_bit(R10BIO_Uptodate, &r10_bio->state))
1382                 generic_make_request(wbio);
1383         else
1384                 bio_endio(wbio, -EIO);
1385 }
1386
1387
1388 /*
1389  * Used by fix_read_error() to decay the per rdev read_errors.
1390  * We halve the read error count for every hour that has elapsed
1391  * since the last recorded read error.
1392  *
1393  */
1394 static void check_decay_read_errors(mddev_t *mddev, mdk_rdev_t *rdev)
1395 {
1396         struct timespec cur_time_mon;
1397         unsigned long hours_since_last;
1398         unsigned int read_errors = atomic_read(&rdev->read_errors);
1399
1400         ktime_get_ts(&cur_time_mon);
1401
1402         if (rdev->last_read_error.tv_sec == 0 &&
1403             rdev->last_read_error.tv_nsec == 0) {
1404                 /* first time we've seen a read error */
1405                 rdev->last_read_error = cur_time_mon;
1406                 return;
1407         }
1408
1409         hours_since_last = (cur_time_mon.tv_sec -
1410                             rdev->last_read_error.tv_sec) / 3600;
1411
1412         rdev->last_read_error = cur_time_mon;
1413
1414         /*
1415          * if hours_since_last is > the number of bits in read_errors
1416          * just set read errors to 0. We do this to avoid
1417          * overflowing the shift of read_errors by hours_since_last.
1418          */
1419         if (hours_since_last >= 8 * sizeof(read_errors))
1420                 atomic_set(&rdev->read_errors, 0);
1421         else
1422                 atomic_set(&rdev->read_errors, read_errors >> hours_since_last);
1423 }
1424
1425 /*
1426  * This is a kernel thread which:
1427  *
1428  *      1.      Retries failed read operations on working mirrors.
1429  *      2.      Updates the raid superblock when problems encounter.
1430  *      3.      Performs writes following reads for array synchronising.
1431  */
1432
1433 static void fix_read_error(conf_t *conf, mddev_t *mddev, r10bio_t *r10_bio)
1434 {
1435         int sect = 0; /* Offset from r10_bio->sector */
1436         int sectors = r10_bio->sectors;
1437         mdk_rdev_t*rdev;
1438         int max_read_errors = atomic_read(&mddev->max_corr_read_errors);
1439         int d = r10_bio->devs[r10_bio->read_slot].devnum;
1440
1441         rcu_read_lock();
1442         rdev = rcu_dereference(conf->mirrors[d].rdev);
1443         if (rdev) { /* If rdev is not NULL */
1444                 char b[BDEVNAME_SIZE];
1445                 int cur_read_error_count = 0;
1446
1447                 bdevname(rdev->bdev, b);
1448
1449                 if (test_bit(Faulty, &rdev->flags)) {
1450                         rcu_read_unlock();
1451                         /* drive has already been failed, just ignore any
1452                            more fix_read_error() attempts */
1453                         return;
1454                 }
1455
1456                 check_decay_read_errors(mddev, rdev);
1457                 atomic_inc(&rdev->read_errors);
1458                 cur_read_error_count = atomic_read(&rdev->read_errors);
1459                 if (cur_read_error_count > max_read_errors) {
1460                         rcu_read_unlock();
1461                         printk(KERN_NOTICE
1462                                "md/raid10:%s: %s: Raid device exceeded "
1463                                "read_error threshold "
1464                                "[cur %d:max %d]\n",
1465                                mdname(mddev),
1466                                b, cur_read_error_count, max_read_errors);
1467                         printk(KERN_NOTICE
1468                                "md/raid10:%s: %s: Failing raid "
1469                                "device\n", mdname(mddev), b);
1470                         md_error(mddev, conf->mirrors[d].rdev);
1471                         return;
1472                 }
1473         }
1474         rcu_read_unlock();
1475
1476         while(sectors) {
1477                 int s = sectors;
1478                 int sl = r10_bio->read_slot;
1479                 int success = 0;
1480                 int start;
1481
1482                 if (s > (PAGE_SIZE>>9))
1483                         s = PAGE_SIZE >> 9;
1484
1485                 rcu_read_lock();
1486                 do {
1487                         d = r10_bio->devs[sl].devnum;
1488                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1489                         if (rdev &&
1490                             test_bit(In_sync, &rdev->flags)) {
1491                                 atomic_inc(&rdev->nr_pending);
1492                                 rcu_read_unlock();
1493                                 success = sync_page_io(rdev,
1494                                                        r10_bio->devs[sl].addr +
1495                                                        sect,
1496                                                        s<<9,
1497                                                        conf->tmppage, READ, false);
1498                                 rdev_dec_pending(rdev, mddev);
1499                                 rcu_read_lock();
1500                                 if (success)
1501                                         break;
1502                         }
1503                         sl++;
1504                         if (sl == conf->copies)
1505                                 sl = 0;
1506                 } while (!success && sl != r10_bio->read_slot);
1507                 rcu_read_unlock();
1508
1509                 if (!success) {
1510                         /* Cannot read from anywhere -- bye bye array */
1511                         int dn = r10_bio->devs[r10_bio->read_slot].devnum;
1512                         md_error(mddev, conf->mirrors[dn].rdev);
1513                         break;
1514                 }
1515
1516                 start = sl;
1517                 /* write it back and re-read */
1518                 rcu_read_lock();
1519                 while (sl != r10_bio->read_slot) {
1520                         char b[BDEVNAME_SIZE];
1521
1522                         if (sl==0)
1523                                 sl = conf->copies;
1524                         sl--;
1525                         d = r10_bio->devs[sl].devnum;
1526                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1527                         if (rdev &&
1528                             test_bit(In_sync, &rdev->flags)) {
1529                                 atomic_inc(&rdev->nr_pending);
1530                                 rcu_read_unlock();
1531                                 atomic_add(s, &rdev->corrected_errors);
1532                                 if (sync_page_io(rdev,
1533                                                  r10_bio->devs[sl].addr +
1534                                                  sect,
1535                                                  s<<9, conf->tmppage, WRITE, false)
1536                                     == 0) {
1537                                         /* Well, this device is dead */
1538                                         printk(KERN_NOTICE
1539                                                "md/raid10:%s: read correction "
1540                                                "write failed"
1541                                                " (%d sectors at %llu on %s)\n",
1542                                                mdname(mddev), s,
1543                                                (unsigned long long)(sect+
1544                                                rdev->data_offset),
1545                                                bdevname(rdev->bdev, b));
1546                                         printk(KERN_NOTICE "md/raid10:%s: %s: failing "
1547                                                "drive\n",
1548                                                mdname(mddev),
1549                                                bdevname(rdev->bdev, b));
1550                                         md_error(mddev, rdev);
1551                                 }
1552                                 rdev_dec_pending(rdev, mddev);
1553                                 rcu_read_lock();
1554                         }
1555                 }
1556                 sl = start;
1557                 while (sl != r10_bio->read_slot) {
1558
1559                         if (sl==0)
1560                                 sl = conf->copies;
1561                         sl--;
1562                         d = r10_bio->devs[sl].devnum;
1563                         rdev = rcu_dereference(conf->mirrors[d].rdev);
1564                         if (rdev &&
1565                             test_bit(In_sync, &rdev->flags)) {
1566                                 char b[BDEVNAME_SIZE];
1567                                 atomic_inc(&rdev->nr_pending);
1568                                 rcu_read_unlock();
1569                                 if (sync_page_io(rdev,
1570                                                  r10_bio->devs[sl].addr +
1571                                                  sect,
1572                                                  s<<9, conf->tmppage,
1573                                                  READ, false) == 0) {
1574                                         /* Well, this device is dead */
1575                                         printk(KERN_NOTICE
1576                                                "md/raid10:%s: unable to read back "
1577                                                "corrected sectors"
1578                                                " (%d sectors at %llu on %s)\n",
1579                                                mdname(mddev), s,
1580                                                (unsigned long long)(sect+
1581                                                     rdev->data_offset),
1582                                                bdevname(rdev->bdev, b));
1583                                         printk(KERN_NOTICE "md/raid10:%s: %s: failing drive\n",
1584                                                mdname(mddev),
1585                                                bdevname(rdev->bdev, b));
1586
1587                                         md_error(mddev, rdev);
1588                                 } else {
1589                                         printk(KERN_INFO
1590                                                "md/raid10:%s: read error corrected"
1591                                                " (%d sectors at %llu on %s)\n",
1592                                                mdname(mddev), s,
1593                                                (unsigned long long)(sect+
1594                                                     rdev->data_offset),
1595                                                bdevname(rdev->bdev, b));
1596                                 }
1597
1598                                 rdev_dec_pending(rdev, mddev);
1599                                 rcu_read_lock();
1600                         }
1601                 }
1602                 rcu_read_unlock();
1603
1604                 sectors -= s;
1605                 sect += s;
1606         }
1607 }
1608
1609 static void raid10d(mddev_t *mddev)
1610 {
1611         r10bio_t *r10_bio;
1612         struct bio *bio;
1613         unsigned long flags;
1614         conf_t *conf = mddev->private;
1615         struct list_head *head = &conf->retry_list;
1616         mdk_rdev_t *rdev;
1617         struct blk_plug plug;
1618
1619         md_check_recovery(mddev);
1620
1621         blk_start_plug(&plug);
1622         for (;;) {
1623                 char b[BDEVNAME_SIZE];
1624
1625                 flush_pending_writes(conf);
1626
1627                 spin_lock_irqsave(&conf->device_lock, flags);
1628                 if (list_empty(head)) {
1629                         spin_unlock_irqrestore(&conf->device_lock, flags);
1630                         break;
1631                 }
1632                 r10_bio = list_entry(head->prev, r10bio_t, retry_list);
1633                 list_del(head->prev);
1634                 conf->nr_queued--;
1635                 spin_unlock_irqrestore(&conf->device_lock, flags);
1636
1637                 mddev = r10_bio->mddev;
1638                 conf = mddev->private;
1639                 if (test_bit(R10BIO_IsSync, &r10_bio->state))
1640                         sync_request_write(mddev, r10_bio);
1641                 else if (test_bit(R10BIO_IsRecover, &r10_bio->state))
1642                         recovery_request_write(mddev, r10_bio);
1643                 else {
1644                         int mirror;
1645                         /* we got a read error. Maybe the drive is bad.  Maybe just
1646                          * the block and we can fix it.
1647                          * We freeze all other IO, and try reading the block from
1648                          * other devices.  When we find one, we re-write
1649                          * and check it that fixes the read error.
1650                          * This is all done synchronously while the array is
1651                          * frozen.
1652                          */
1653                         if (mddev->ro == 0) {
1654                                 freeze_array(conf);
1655                                 fix_read_error(conf, mddev, r10_bio);
1656                                 unfreeze_array(conf);
1657                         }
1658
1659                         bio = r10_bio->devs[r10_bio->read_slot].bio;
1660                         r10_bio->devs[r10_bio->read_slot].bio =
1661                                 mddev->ro ? IO_BLOCKED : NULL;
1662                         mirror = read_balance(conf, r10_bio);
1663                         if (mirror == -1) {
1664                                 printk(KERN_ALERT "md/raid10:%s: %s: unrecoverable I/O"
1665                                        " read error for block %llu\n",
1666                                        mdname(mddev),
1667                                        bdevname(bio->bi_bdev,b),
1668                                        (unsigned long long)r10_bio->sector);
1669                                 raid_end_bio_io(r10_bio);
1670                                 bio_put(bio);
1671                         } else {
1672                                 const unsigned long do_sync = (r10_bio->master_bio->bi_rw & REQ_SYNC);
1673                                 bio_put(bio);
1674                                 rdev = conf->mirrors[mirror].rdev;
1675                                 if (printk_ratelimit())
1676                                         printk(KERN_ERR "md/raid10:%s: %s: redirecting sector %llu to"
1677                                                " another mirror\n",
1678                                                mdname(mddev),
1679                                                bdevname(rdev->bdev,b),
1680                                                (unsigned long long)r10_bio->sector);
1681                                 bio = bio_clone_mddev(r10_bio->master_bio,
1682                                                       GFP_NOIO, mddev);
1683                                 r10_bio->devs[r10_bio->read_slot].bio = bio;
1684                                 bio->bi_sector = r10_bio->devs[r10_bio->read_slot].addr
1685                                         + rdev->data_offset;
1686                                 bio->bi_bdev = rdev->bdev;
1687                                 bio->bi_rw = READ | do_sync;
1688                                 bio->bi_private = r10_bio;
1689                                 bio->bi_end_io = raid10_end_read_request;
1690                                 generic_make_request(bio);
1691                         }
1692                 }
1693                 cond_resched();
1694         }
1695         blk_finish_plug(&plug);
1696 }
1697
1698
1699 static int init_resync(conf_t *conf)
1700 {
1701         int buffs;
1702
1703         buffs = RESYNC_WINDOW / RESYNC_BLOCK_SIZE;
1704         BUG_ON(conf->r10buf_pool);
1705         conf->r10buf_pool = mempool_create(buffs, r10buf_pool_alloc, r10buf_pool_free, conf);
1706         if (!conf->r10buf_pool)
1707                 return -ENOMEM;
1708         conf->next_resync = 0;
1709         return 0;
1710 }
1711
1712 /*
1713  * perform a "sync" on one "block"
1714  *
1715  * We need to make sure that no normal I/O request - particularly write
1716  * requests - conflict with active sync requests.
1717  *
1718  * This is achieved by tracking pending requests and a 'barrier' concept
1719  * that can be installed to exclude normal IO requests.
1720  *
1721  * Resync and recovery are handled very differently.
1722  * We differentiate by looking at MD_RECOVERY_SYNC in mddev->recovery.
1723  *
1724  * For resync, we iterate over virtual addresses, read all copies,
1725  * and update if there are differences.  If only one copy is live,
1726  * skip it.
1727  * For recovery, we iterate over physical addresses, read a good
1728  * value for each non-in_sync drive, and over-write.
1729  *
1730  * So, for recovery we may have several outstanding complex requests for a
1731  * given address, one for each out-of-sync device.  We model this by allocating
1732  * a number of r10_bio structures, one for each out-of-sync device.
1733  * As we setup these structures, we collect all bio's together into a list
1734  * which we then process collectively to add pages, and then process again
1735  * to pass to generic_make_request.
1736  *
1737  * The r10_bio structures are linked using a borrowed master_bio pointer.
1738  * This link is counted in ->remaining.  When the r10_bio that points to NULL
1739  * has its remaining count decremented to 0, the whole complex operation
1740  * is complete.
1741  *
1742  */
1743
1744 static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster)
1745 {
1746         conf_t *conf = mddev->private;
1747         r10bio_t *r10_bio;
1748         struct bio *biolist = NULL, *bio;
1749         sector_t max_sector, nr_sectors;
1750         int disk;
1751         int i;
1752         int max_sync;
1753         sector_t sync_blocks;
1754
1755         sector_t sectors_skipped = 0;
1756         int chunks_skipped = 0;
1757
1758         if (!conf->r10buf_pool)
1759                 if (init_resync(conf))
1760                         return 0;
1761
1762  skipped:
1763         max_sector = mddev->dev_sectors;
1764         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
1765                 max_sector = mddev->resync_max_sectors;
1766         if (sector_nr >= max_sector) {
1767                 /* If we aborted, we need to abort the
1768                  * sync on the 'current' bitmap chucks (there can
1769                  * be several when recovering multiple devices).
1770                  * as we may have started syncing it but not finished.
1771                  * We can find the current address in
1772                  * mddev->curr_resync, but for recovery,
1773                  * we need to convert that to several
1774                  * virtual addresses.
1775                  */
1776                 if (mddev->curr_resync < max_sector) { /* aborted */
1777                         if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
1778                                 bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
1779                                                 &sync_blocks, 1);
1780                         else for (i=0; i<conf->raid_disks; i++) {
1781                                 sector_t sect =
1782                                         raid10_find_virt(conf, mddev->curr_resync, i);
1783                                 bitmap_end_sync(mddev->bitmap, sect,
1784                                                 &sync_blocks, 1);
1785                         }
1786                 } else /* completed sync */
1787                         conf->fullsync = 0;
1788
1789                 bitmap_close_sync(mddev->bitmap);
1790                 close_sync(conf);
1791                 *skipped = 1;
1792                 return sectors_skipped;
1793         }
1794         if (chunks_skipped >= conf->raid_disks) {
1795                 /* if there has been nothing to do on any drive,
1796                  * then there is nothing to do at all..
1797                  */
1798                 *skipped = 1;
1799                 return (max_sector - sector_nr) + sectors_skipped;
1800         }
1801
1802         if (max_sector > mddev->resync_max)
1803                 max_sector = mddev->resync_max; /* Don't do IO beyond here */
1804
1805         /* make sure whole request will fit in a chunk - if chunks
1806          * are meaningful
1807          */
1808         if (conf->near_copies < conf->raid_disks &&
1809             max_sector > (sector_nr | conf->chunk_mask))
1810                 max_sector = (sector_nr | conf->chunk_mask) + 1;
1811         /*
1812          * If there is non-resync activity waiting for us then
1813          * put in a delay to throttle resync.
1814          */
1815         if (!go_faster && conf->nr_waiting)
1816                 msleep_interruptible(1000);
1817
1818         /* Again, very different code for resync and recovery.
1819          * Both must result in an r10bio with a list of bios that
1820          * have bi_end_io, bi_sector, bi_bdev set,
1821          * and bi_private set to the r10bio.
1822          * For recovery, we may actually create several r10bios
1823          * with 2 bios in each, that correspond to the bios in the main one.
1824          * In this case, the subordinate r10bios link back through a
1825          * borrowed master_bio pointer, and the counter in the master
1826          * includes a ref from each subordinate.
1827          */
1828         /* First, we decide what to do and set ->bi_end_io
1829          * To end_sync_read if we want to read, and
1830          * end_sync_write if we will want to write.
1831          */
1832
1833         max_sync = RESYNC_PAGES << (PAGE_SHIFT-9);
1834         if (!test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
1835                 /* recovery... the complicated one */
1836                 int j, k;
1837                 r10_bio = NULL;
1838
1839                 for (i=0 ; i<conf->raid_disks; i++)
1840                         if (conf->mirrors[i].rdev &&
1841                             !test_bit(In_sync, &conf->mirrors[i].rdev->flags)) {
1842                                 int still_degraded = 0;
1843                                 /* want to reconstruct this device */
1844                                 r10bio_t *rb2 = r10_bio;
1845                                 sector_t sect = raid10_find_virt(conf, sector_nr, i);
1846                                 int must_sync;
1847                                 /* Unless we are doing a full sync, we only need
1848                                  * to recover the block if it is set in the bitmap
1849                                  */
1850                                 must_sync = bitmap_start_sync(mddev->bitmap, sect,
1851                                                               &sync_blocks, 1);
1852                                 if (sync_blocks < max_sync)
1853                                         max_sync = sync_blocks;
1854                                 if (!must_sync &&
1855                                     !conf->fullsync) {
1856                                         /* yep, skip the sync_blocks here, but don't assume
1857                                          * that there will never be anything to do here
1858                                          */
1859                                         chunks_skipped = -1;
1860                                         continue;
1861                                 }
1862
1863                                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
1864                                 raise_barrier(conf, rb2 != NULL);
1865                                 atomic_set(&r10_bio->remaining, 0);
1866
1867                                 r10_bio->master_bio = (struct bio*)rb2;
1868                                 if (rb2)
1869                                         atomic_inc(&rb2->remaining);
1870                                 r10_bio->mddev = mddev;
1871                                 set_bit(R10BIO_IsRecover, &r10_bio->state);
1872                                 r10_bio->sector = sect;
1873
1874                                 raid10_find_phys(conf, r10_bio);
1875
1876                                 /* Need to check if the array will still be
1877                                  * degraded
1878                                  */
1879                                 for (j=0; j<conf->raid_disks; j++)
1880                                         if (conf->mirrors[j].rdev == NULL ||
1881                                             test_bit(Faulty, &conf->mirrors[j].rdev->flags)) {
1882                                                 still_degraded = 1;
1883                                                 break;
1884                                         }
1885
1886                                 must_sync = bitmap_start_sync(mddev->bitmap, sect,
1887                                                               &sync_blocks, still_degraded);
1888
1889                                 for (j=0; j<conf->copies;j++) {
1890                                         int d = r10_bio->devs[j].devnum;
1891                                         if (conf->mirrors[d].rdev &&
1892                                             test_bit(In_sync, &conf->mirrors[d].rdev->flags)) {
1893                                                 /* This is where we read from */
1894                                                 bio = r10_bio->devs[0].bio;
1895                                                 bio->bi_next = biolist;
1896                                                 biolist = bio;
1897                                                 bio->bi_private = r10_bio;
1898                                                 bio->bi_end_io = end_sync_read;
1899                                                 bio->bi_rw = READ;
1900                                                 bio->bi_sector = r10_bio->devs[j].addr +
1901                                                         conf->mirrors[d].rdev->data_offset;
1902                                                 bio->bi_bdev = conf->mirrors[d].rdev->bdev;
1903                                                 atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1904                                                 atomic_inc(&r10_bio->remaining);
1905                                                 /* and we write to 'i' */
1906
1907                                                 for (k=0; k<conf->copies; k++)
1908                                                         if (r10_bio->devs[k].devnum == i)
1909                                                                 break;
1910                                                 BUG_ON(k == conf->copies);
1911                                                 bio = r10_bio->devs[1].bio;
1912                                                 bio->bi_next = biolist;
1913                                                 biolist = bio;
1914                                                 bio->bi_private = r10_bio;
1915                                                 bio->bi_end_io = end_sync_write;
1916                                                 bio->bi_rw = WRITE;
1917                                                 bio->bi_sector = r10_bio->devs[k].addr +
1918                                                         conf->mirrors[i].rdev->data_offset;
1919                                                 bio->bi_bdev = conf->mirrors[i].rdev->bdev;
1920
1921                                                 r10_bio->devs[0].devnum = d;
1922                                                 r10_bio->devs[1].devnum = i;
1923
1924                                                 break;
1925                                         }
1926                                 }
1927                                 if (j == conf->copies) {
1928                                         /* Cannot recover, so abort the recovery */
1929                                         put_buf(r10_bio);
1930                                         if (rb2)
1931                                                 atomic_dec(&rb2->remaining);
1932                                         r10_bio = rb2;
1933                                         if (!test_and_set_bit(MD_RECOVERY_INTR,
1934                                                               &mddev->recovery))
1935                                                 printk(KERN_INFO "md/raid10:%s: insufficient "
1936                                                        "working devices for recovery.\n",
1937                                                        mdname(mddev));
1938                                         break;
1939                                 }
1940                         }
1941                 if (biolist == NULL) {
1942                         while (r10_bio) {
1943                                 r10bio_t *rb2 = r10_bio;
1944                                 r10_bio = (r10bio_t*) rb2->master_bio;
1945                                 rb2->master_bio = NULL;
1946                                 put_buf(rb2);
1947                         }
1948                         goto giveup;
1949                 }
1950         } else {
1951                 /* resync. Schedule a read for every block at this virt offset */
1952                 int count = 0;
1953
1954                 bitmap_cond_end_sync(mddev->bitmap, sector_nr);
1955
1956                 if (!bitmap_start_sync(mddev->bitmap, sector_nr,
1957                                        &sync_blocks, mddev->degraded) &&
1958                     !conf->fullsync && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
1959                         /* We can skip this block */
1960                         *skipped = 1;
1961                         return sync_blocks + sectors_skipped;
1962                 }
1963                 if (sync_blocks < max_sync)
1964                         max_sync = sync_blocks;
1965                 r10_bio = mempool_alloc(conf->r10buf_pool, GFP_NOIO);
1966
1967                 r10_bio->mddev = mddev;
1968                 atomic_set(&r10_bio->remaining, 0);
1969                 raise_barrier(conf, 0);
1970                 conf->next_resync = sector_nr;
1971
1972                 r10_bio->master_bio = NULL;
1973                 r10_bio->sector = sector_nr;
1974                 set_bit(R10BIO_IsSync, &r10_bio->state);
1975                 raid10_find_phys(conf, r10_bio);
1976                 r10_bio->sectors = (sector_nr | conf->chunk_mask) - sector_nr +1;
1977
1978                 for (i=0; i<conf->copies; i++) {
1979                         int d = r10_bio->devs[i].devnum;
1980                         bio = r10_bio->devs[i].bio;
1981                         bio->bi_end_io = NULL;
1982                         clear_bit(BIO_UPTODATE, &bio->bi_flags);
1983                         if (conf->mirrors[d].rdev == NULL ||
1984                             test_bit(Faulty, &conf->mirrors[d].rdev->flags))
1985                                 continue;
1986                         atomic_inc(&conf->mirrors[d].rdev->nr_pending);
1987                         atomic_inc(&r10_bio->remaining);
1988                         bio->bi_next = biolist;
1989                         biolist = bio;
1990                         bio->bi_private = r10_bio;
1991                         bio->bi_end_io = end_sync_read;
1992                         bio->bi_rw = READ;
1993                         bio->bi_sector = r10_bio->devs[i].addr +
1994                                 conf->mirrors[d].rdev->data_offset;
1995                         bio->bi_bdev = conf->mirrors[d].rdev->bdev;
1996                         count++;
1997                 }
1998
1999                 if (count < 2) {
2000                         for (i=0; i<conf->copies; i++) {
2001                                 int d = r10_bio->devs[i].devnum;
2002                                 if (r10_bio->devs[i].bio->bi_end_io)
2003                                         rdev_dec_pending(conf->mirrors[d].rdev, mddev);
2004                         }
2005                         put_buf(r10_bio);
2006                         biolist = NULL;
2007                         goto giveup;
2008                 }
2009         }
2010
2011         for (bio = biolist; bio ; bio=bio->bi_next) {
2012
2013                 bio->bi_flags &= ~(BIO_POOL_MASK - 1);
2014                 if (bio->bi_end_io)
2015                         bio->bi_flags |= 1 << BIO_UPTODATE;
2016                 bio->bi_vcnt = 0;
2017                 bio->bi_idx = 0;
2018                 bio->bi_phys_segments = 0;
2019                 bio->bi_size = 0;
2020         }
2021
2022         nr_sectors = 0;
2023         if (sector_nr + max_sync < max_sector)
2024                 max_sector = sector_nr + max_sync;
2025         do {
2026                 struct page *page;
2027                 int len = PAGE_SIZE;
2028                 disk = 0;
2029                 if (sector_nr + (len>>9) > max_sector)
2030                         len = (max_sector - sector_nr) << 9;
2031                 if (len == 0)
2032                         break;
2033                 for (bio= biolist ; bio ; bio=bio->bi_next) {
2034                         page = bio->bi_io_vec[bio->bi_vcnt].bv_page;
2035                         if (bio_add_page(bio, page, len, 0) == 0) {
2036                                 /* stop here */
2037                                 struct bio *bio2;
2038                                 bio->bi_io_vec[bio->bi_vcnt].bv_page = page;
2039                                 for (bio2 = biolist; bio2 && bio2 != bio; bio2 = bio2->bi_next) {
2040                                         /* remove last page from this bio */
2041                                         bio2->bi_vcnt--;
2042                                         bio2->bi_size -= len;
2043                                         bio2->bi_flags &= ~(1<< BIO_SEG_VALID);
2044                                 }
2045                                 goto bio_full;
2046                         }
2047                         disk = i;
2048                 }
2049                 nr_sectors += len>>9;
2050                 sector_nr += len>>9;
2051         } while (biolist->bi_vcnt < RESYNC_PAGES);
2052  bio_full:
2053         r10_bio->sectors = nr_sectors;
2054
2055         while (biolist) {
2056                 bio = biolist;
2057                 biolist = biolist->bi_next;
2058
2059                 bio->bi_next = NULL;
2060                 r10_bio = bio->bi_private;
2061                 r10_bio->sectors = nr_sectors;
2062
2063                 if (bio->bi_end_io == end_sync_read) {
2064                         md_sync_acct(bio->bi_bdev, nr_sectors);
2065                         generic_make_request(bio);
2066                 }
2067         }
2068
2069         if (sectors_skipped)
2070                 /* pretend they weren't skipped, it makes
2071                  * no important difference in this case
2072                  */
2073                 md_done_sync(mddev, sectors_skipped, 1);
2074
2075         return sectors_skipped + nr_sectors;
2076  giveup:
2077         /* There is nowhere to write, so all non-sync
2078          * drives must be failed, so try the next chunk...
2079          */
2080         if (sector_nr + max_sync < max_sector)
2081                 max_sector = sector_nr + max_sync;
2082
2083         sectors_skipped += (max_sector - sector_nr);
2084         chunks_skipped ++;
2085         sector_nr = max_sector;
2086         goto skipped;
2087 }
2088
2089 static sector_t
2090 raid10_size(mddev_t *mddev, sector_t sectors, int raid_disks)
2091 {
2092         sector_t size;
2093         conf_t *conf = mddev->private;
2094
2095         if (!raid_disks)
2096                 raid_disks = conf->raid_disks;
2097         if (!sectors)
2098                 sectors = conf->dev_sectors;
2099
2100         size = sectors >> conf->chunk_shift;
2101         sector_div(size, conf->far_copies);
2102         size = size * raid_disks;
2103         sector_div(size, conf->near_copies);
2104
2105         return size << conf->chunk_shift;
2106 }
2107
2108
2109 static conf_t *setup_conf(mddev_t *mddev)
2110 {
2111         conf_t *conf = NULL;
2112         int nc, fc, fo;
2113         sector_t stride, size;
2114         int err = -EINVAL;
2115
2116         if (mddev->new_chunk_sectors < (PAGE_SIZE >> 9) ||
2117             !is_power_of_2(mddev->new_chunk_sectors)) {
2118                 printk(KERN_ERR "md/raid10:%s: chunk size must be "
2119                        "at least PAGE_SIZE(%ld) and be a power of 2.\n",
2120                        mdname(mddev), PAGE_SIZE);
2121                 goto out;
2122         }
2123
2124         nc = mddev->new_layout & 255;
2125         fc = (mddev->new_layout >> 8) & 255;
2126         fo = mddev->new_layout & (1<<16);
2127
2128         if ((nc*fc) <2 || (nc*fc) > mddev->raid_disks ||
2129             (mddev->new_layout >> 17)) {
2130                 printk(KERN_ERR "md/raid10:%s: unsupported raid10 layout: 0x%8x\n",
2131                        mdname(mddev), mddev->new_layout);
2132                 goto out;
2133         }
2134
2135         err = -ENOMEM;
2136         conf = kzalloc(sizeof(conf_t), GFP_KERNEL);
2137         if (!conf)
2138                 goto out;
2139
2140         conf->mirrors = kzalloc(sizeof(struct mirror_info)*mddev->raid_disks,
2141                                 GFP_KERNEL);
2142         if (!conf->mirrors)
2143                 goto out;
2144
2145         conf->tmppage = alloc_page(GFP_KERNEL);
2146         if (!conf->tmppage)
2147                 goto out;
2148
2149
2150         conf->raid_disks = mddev->raid_disks;
2151         conf->near_copies = nc;
2152         conf->far_copies = fc;
2153         conf->copies = nc*fc;
2154         conf->far_offset = fo;
2155         conf->chunk_mask = mddev->new_chunk_sectors - 1;
2156         conf->chunk_shift = ffz(~mddev->new_chunk_sectors);
2157
2158         conf->r10bio_pool = mempool_create(NR_RAID10_BIOS, r10bio_pool_alloc,
2159                                            r10bio_pool_free, conf);
2160         if (!conf->r10bio_pool)
2161                 goto out;
2162
2163         size = mddev->dev_sectors >> conf->chunk_shift;
2164         sector_div(size, fc);
2165         size = size * conf->raid_disks;
2166         sector_div(size, nc);
2167         /* 'size' is now the number of chunks in the array */
2168         /* calculate "used chunks per device" in 'stride' */
2169         stride = size * conf->copies;
2170
2171         /* We need to round up when dividing by raid_disks to
2172          * get the stride size.
2173          */
2174         stride += conf->raid_disks - 1;
2175         sector_div(stride, conf->raid_disks);
2176
2177         conf->dev_sectors = stride << conf->chunk_shift;
2178
2179         if (fo)
2180                 stride = 1;
2181         else
2182                 sector_div(stride, fc);
2183         conf->stride = stride << conf->chunk_shift;
2184
2185
2186         spin_lock_init(&conf->device_lock);
2187         INIT_LIST_HEAD(&conf->retry_list);
2188
2189         spin_lock_init(&conf->resync_lock);
2190         init_waitqueue_head(&conf->wait_barrier);
2191
2192         conf->thread = md_register_thread(raid10d, mddev, NULL);
2193         if (!conf->thread)
2194                 goto out;
2195
2196         conf->mddev = mddev;
2197         return conf;
2198
2199  out:
2200         printk(KERN_ERR "md/raid10:%s: couldn't allocate memory.\n",
2201                mdname(mddev));
2202         if (conf) {
2203                 if (conf->r10bio_pool)
2204                         mempool_destroy(conf->r10bio_pool);
2205                 kfree(conf->mirrors);
2206                 safe_put_page(conf->tmppage);
2207                 kfree(conf);
2208         }
2209         return ERR_PTR(err);
2210 }
2211
2212 static int run(mddev_t *mddev)
2213 {
2214         conf_t *conf;
2215         int i, disk_idx, chunk_size;
2216         mirror_info_t *disk;
2217         mdk_rdev_t *rdev;
2218         sector_t size;
2219
2220         /*
2221          * copy the already verified devices into our private RAID10
2222          * bookkeeping area. [whatever we allocate in run(),
2223          * should be freed in stop()]
2224          */
2225
2226         if (mddev->private == NULL) {
2227                 conf = setup_conf(mddev);
2228                 if (IS_ERR(conf))
2229                         return PTR_ERR(conf);
2230                 mddev->private = conf;
2231         }
2232         conf = mddev->private;
2233         if (!conf)
2234                 goto out;
2235
2236         mddev->thread = conf->thread;
2237         conf->thread = NULL;
2238
2239         chunk_size = mddev->chunk_sectors << 9;
2240         blk_queue_io_min(mddev->queue, chunk_size);
2241         if (conf->raid_disks % conf->near_copies)
2242                 blk_queue_io_opt(mddev->queue, chunk_size * conf->raid_disks);
2243         else
2244                 blk_queue_io_opt(mddev->queue, chunk_size *
2245                                  (conf->raid_disks / conf->near_copies));
2246
2247         list_for_each_entry(rdev, &mddev->disks, same_set) {
2248                 disk_idx = rdev->raid_disk;
2249                 if (disk_idx >= conf->raid_disks
2250                     || disk_idx < 0)
2251                         continue;
2252                 disk = conf->mirrors + disk_idx;
2253
2254                 disk->rdev = rdev;
2255                 disk_stack_limits(mddev->gendisk, rdev->bdev,
2256                                   rdev->data_offset << 9);
2257                 /* as we don't honour merge_bvec_fn, we must never risk
2258                  * violating it, so limit max_segments to 1 lying
2259                  * within a single page.
2260                  */
2261                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
2262                         blk_queue_max_segments(mddev->queue, 1);
2263                         blk_queue_segment_boundary(mddev->queue,
2264                                                    PAGE_CACHE_SIZE - 1);
2265                 }
2266
2267                 disk->head_position = 0;
2268         }
2269         /* need to check that every block has at least one working mirror */
2270         if (!enough(conf)) {
2271                 printk(KERN_ERR "md/raid10:%s: not enough operational mirrors.\n",
2272                        mdname(mddev));
2273                 goto out_free_conf;
2274         }
2275
2276         mddev->degraded = 0;
2277         for (i = 0; i < conf->raid_disks; i++) {
2278
2279                 disk = conf->mirrors + i;
2280
2281                 if (!disk->rdev ||
2282                     !test_bit(In_sync, &disk->rdev->flags)) {
2283                         disk->head_position = 0;
2284                         mddev->degraded++;
2285                         if (disk->rdev)
2286                                 conf->fullsync = 1;
2287                 }
2288         }
2289
2290         if (mddev->recovery_cp != MaxSector)
2291                 printk(KERN_NOTICE "md/raid10:%s: not clean"
2292                        " -- starting background reconstruction\n",
2293                        mdname(mddev));
2294         printk(KERN_INFO
2295                 "md/raid10:%s: active with %d out of %d devices\n",
2296                 mdname(mddev), conf->raid_disks - mddev->degraded,
2297                 conf->raid_disks);
2298         /*
2299          * Ok, everything is just fine now
2300          */
2301         mddev->dev_sectors = conf->dev_sectors;
2302         size = raid10_size(mddev, 0, 0);
2303         md_set_array_sectors(mddev, size);
2304         mddev->resync_max_sectors = size;
2305
2306         mddev->queue->backing_dev_info.congested_fn = raid10_congested;
2307         mddev->queue->backing_dev_info.congested_data = mddev;
2308
2309         /* Calculate max read-ahead size.
2310          * We need to readahead at least twice a whole stripe....
2311          * maybe...
2312          */
2313         {
2314                 int stripe = conf->raid_disks *
2315                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
2316                 stripe /= conf->near_copies;
2317                 if (mddev->queue->backing_dev_info.ra_pages < 2* stripe)
2318                         mddev->queue->backing_dev_info.ra_pages = 2* stripe;
2319         }
2320
2321         if (conf->near_copies < conf->raid_disks)
2322                 blk_queue_merge_bvec(mddev->queue, raid10_mergeable_bvec);
2323
2324         if (md_integrity_register(mddev))
2325                 goto out_free_conf;
2326
2327         return 0;
2328
2329 out_free_conf:
2330         md_unregister_thread(mddev->thread);
2331         if (conf->r10bio_pool)
2332                 mempool_destroy(conf->r10bio_pool);
2333         safe_put_page(conf->tmppage);
2334         kfree(conf->mirrors);
2335         kfree(conf);
2336         mddev->private = NULL;
2337 out:
2338         return -EIO;
2339 }
2340
2341 static int stop(mddev_t *mddev)
2342 {
2343         conf_t *conf = mddev->private;
2344
2345         raise_barrier(conf, 0);
2346         lower_barrier(conf);
2347
2348         md_unregister_thread(mddev->thread);
2349         mddev->thread = NULL;
2350         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
2351         if (conf->r10bio_pool)
2352                 mempool_destroy(conf->r10bio_pool);
2353         kfree(conf->mirrors);
2354         kfree(conf);
2355         mddev->private = NULL;
2356         return 0;
2357 }
2358
2359 static void raid10_quiesce(mddev_t *mddev, int state)
2360 {
2361         conf_t *conf = mddev->private;
2362
2363         switch(state) {
2364         case 1:
2365                 raise_barrier(conf, 0);
2366                 break;
2367         case 0:
2368                 lower_barrier(conf);
2369                 break;
2370         }
2371 }
2372
2373 static void *raid10_takeover_raid0(mddev_t *mddev)
2374 {
2375         mdk_rdev_t *rdev;
2376         conf_t *conf;
2377
2378         if (mddev->degraded > 0) {
2379                 printk(KERN_ERR "md/raid10:%s: Error: degraded raid0!\n",
2380                        mdname(mddev));
2381                 return ERR_PTR(-EINVAL);
2382         }
2383
2384         /* Set new parameters */
2385         mddev->new_level = 10;
2386         /* new layout: far_copies = 1, near_copies = 2 */
2387         mddev->new_layout = (1<<8) + 2;
2388         mddev->new_chunk_sectors = mddev->chunk_sectors;
2389         mddev->delta_disks = mddev->raid_disks;
2390         mddev->raid_disks *= 2;
2391         /* make sure it will be not marked as dirty */
2392         mddev->recovery_cp = MaxSector;
2393
2394         conf = setup_conf(mddev);
2395         if (!IS_ERR(conf)) {
2396                 list_for_each_entry(rdev, &mddev->disks, same_set)
2397                         if (rdev->raid_disk >= 0)
2398                                 rdev->new_raid_disk = rdev->raid_disk * 2;
2399                 conf->barrier = 1;
2400         }
2401
2402         return conf;
2403 }
2404
2405 static void *raid10_takeover(mddev_t *mddev)
2406 {
2407         struct raid0_private_data *raid0_priv;
2408
2409         /* raid10 can take over:
2410          *  raid0 - providing it has only two drives
2411          */
2412         if (mddev->level == 0) {
2413                 /* for raid0 takeover only one zone is supported */
2414                 raid0_priv = mddev->private;
2415                 if (raid0_priv->nr_strip_zones > 1) {
2416                         printk(KERN_ERR "md/raid10:%s: cannot takeover raid 0"
2417                                " with more than one zone.\n",
2418                                mdname(mddev));
2419                         return ERR_PTR(-EINVAL);
2420                 }
2421                 return raid10_takeover_raid0(mddev);
2422         }
2423         return ERR_PTR(-EINVAL);
2424 }
2425
2426 static struct mdk_personality raid10_personality =
2427 {
2428         .name           = "raid10",
2429         .level          = 10,
2430         .owner          = THIS_MODULE,
2431         .make_request   = make_request,
2432         .run            = run,
2433         .stop           = stop,
2434         .status         = status,
2435         .error_handler  = error,
2436         .hot_add_disk   = raid10_add_disk,
2437         .hot_remove_disk= raid10_remove_disk,
2438         .spare_active   = raid10_spare_active,
2439         .sync_request   = sync_request,
2440         .quiesce        = raid10_quiesce,
2441         .size           = raid10_size,
2442         .takeover       = raid10_takeover,
2443 };
2444
2445 static int __init raid_init(void)
2446 {
2447         return register_md_personality(&raid10_personality);
2448 }
2449
2450 static void raid_exit(void)
2451 {
2452         unregister_md_personality(&raid10_personality);
2453 }
2454
2455 module_init(raid_init);
2456 module_exit(raid_exit);
2457 MODULE_LICENSE("GPL");
2458 MODULE_DESCRIPTION("RAID10 (striped mirror) personality for MD");
2459 MODULE_ALIAS("md-personality-9"); /* RAID10 */
2460 MODULE_ALIAS("md-raid10");
2461 MODULE_ALIAS("md-level-10");