block/blk-mq.c

   1 /*
   2  * Block multiqueue core code
   3  *
   4  * Copyright (C) 2013-2014 Jens Axboe
   5  * Copyright (C) 2013-2014 Christoph Hellwig
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/backing-dev.h>
  10 #include <linux/bio.h>
  11 #include <linux/blkdev.h>
  12 #include <linux/mm.h>
  13 #include <linux/init.h>
  14 #include <linux/slab.h>
  15 #include <linux/workqueue.h>
  16 #include <linux/smp.h>
  17 #include <linux/llist.h>
  18 #include <linux/list_sort.h>
  19 #include <linux/cpu.h>
  20 #include <linux/cache.h>
  21 #include <linux/sched/sysctl.h>
  22 #include <linux/delay.h>
  23
  24 #include <trace/events/block.h>
  25
  26 #include <linux/blk-mq.h>
  27 #include "blk.h"
  28 #include "blk-mq.h"
  29 #include "blk-mq-tag.h"
  30
  31 static DEFINE_MUTEX(all_q_mutex);
  32 static LIST_HEAD(all_q_list);
  33
  34 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx);
  35
  36 /*
  37  * Check if any of the ctx's have pending work in this hardware queue
  38  */
  39 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
  40 {
  41         unsigned int i;
  42
  43         for (i = 0; i < hctx->ctx_map.map_size; i++)
  44                 if (hctx->ctx_map.map[i].word)
  45                         return true;
  46
  47         return false;
  48 }
  49
  50 static inline struct blk_align_bitmap *get_bm(struct blk_mq_hw_ctx *hctx,
  51                                               struct blk_mq_ctx *ctx)
  52 {
  53         return &hctx->ctx_map.map[ctx->index_hw / hctx->ctx_map.bits_per_word];
  54 }
  55
  56 #define CTX_TO_BIT(hctx, ctx)   \
  57         ((ctx)->index_hw & ((hctx)->ctx_map.bits_per_word - 1))
  58
  59 /*
  60  * Mark this ctx as having pending work in this hardware queue
  61  */
  62 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
  63                                      struct blk_mq_ctx *ctx)
  64 {
  65         struct blk_align_bitmap *bm = get_bm(hctx, ctx);
  66
  67         if (!test_bit(CTX_TO_BIT(hctx, ctx), &bm->word))
  68                 set_bit(CTX_TO_BIT(hctx, ctx), &bm->word);
  69 }
  70
  71 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
  72                                       struct blk_mq_ctx *ctx)
  73 {
  74         struct blk_align_bitmap *bm = get_bm(hctx, ctx);
  75
  76         clear_bit(CTX_TO_BIT(hctx, ctx), &bm->word);
  77 }
  78
  79 static int blk_mq_queue_enter(struct request_queue *q)
  80 {
  81         while (true) {
  82                 int ret;
  83
  84                 if (percpu_ref_tryget_live(&q->mq_usage_counter))
  85                         return 0;
  86
  87                 ret = wait_event_interruptible(q->mq_freeze_wq,
  88                                 !q->mq_freeze_depth || blk_queue_dying(q));
  89                 if (blk_queue_dying(q))
  90                         return -ENODEV;
  91                 if (ret)
  92                         return ret;
  93         }
  94 }
  95
  96 static void blk_mq_queue_exit(struct request_queue *q)
  97 {
  98         percpu_ref_put(&q->mq_usage_counter);
  99 }
 100
 101 static void blk_mq_usage_counter_release(struct percpu_ref *ref)
 102 {
 103         struct request_queue *q =
 104                 container_of(ref, struct request_queue, mq_usage_counter);
 105
 106         wake_up_all(&q->mq_freeze_wq);
 107 }
 108
 109 /*
 110  * Guarantee no request is in use, so we can change any data structure of
 111  * the queue afterward.
 112  */
 113 void blk_mq_freeze_queue(struct request_queue *q)
 114 {
 115         bool freeze;
 116
 117         spin_lock_irq(q->queue_lock);
 118         freeze = !q->mq_freeze_depth++;
 119         spin_unlock_irq(q->queue_lock);
 120
 121         if (freeze) {
 122                 percpu_ref_kill(&q->mq_usage_counter);
 123                 blk_mq_run_queues(q, false);
 124         }
 125         wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->mq_usage_counter));
 126 }
 127
 128 static void blk_mq_unfreeze_queue(struct request_queue *q)
 129 {
 130         bool wake;
 131
 132         spin_lock_irq(q->queue_lock);
 133         wake = !--q->mq_freeze_depth;
 134         WARN_ON_ONCE(q->mq_freeze_depth < 0);
 135         spin_unlock_irq(q->queue_lock);
 136         if (wake) {
 137                 percpu_ref_reinit(&q->mq_usage_counter);
 138                 wake_up_all(&q->mq_freeze_wq);
 139         }
 140 }
 141
 142 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
 143 {
 144         return blk_mq_has_free_tags(hctx->tags);
 145 }
 146 EXPORT_SYMBOL(blk_mq_can_queue);
 147
 148 static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
 149                                struct request *rq, unsigned int rw_flags)
 150 {
 151         if (blk_queue_io_stat(q))
 152                 rw_flags |= REQ_IO_STAT;
 153
 154         INIT_LIST_HEAD(&rq->queuelist);
 155         /* csd/requeue_work/fifo_time is initialized before use */
 156         rq->q = q;
 157         rq->mq_ctx = ctx;
 158         rq->cmd_flags |= rw_flags;
 159         /* do not touch atomic flags, it needs atomic ops against the timer */
 160         rq->cpu = -1;
 161         INIT_HLIST_NODE(&rq->hash);
 162         RB_CLEAR_NODE(&rq->rb_node);
 163         rq->rq_disk = NULL;
 164         rq->part = NULL;
 165         rq->start_time = jiffies;
 166 #ifdef CONFIG_BLK_CGROUP
 167         rq->rl = NULL;
 168         set_start_time_ns(rq);
 169         rq->io_start_time_ns = 0;
 170 #endif
 171         rq->nr_phys_segments = 0;
 172 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 173         rq->nr_integrity_segments = 0;
 174 #endif
 175         rq->special = NULL;
 176         /* tag was already set */
 177         rq->errors = 0;
 178
 179         rq->cmd = rq->__cmd;
 180
 181         rq->extra_len = 0;
 182         rq->sense_len = 0;
 183         rq->resid_len = 0;
 184         rq->sense = NULL;
 185
 186         INIT_LIST_HEAD(&rq->timeout_list);
 187         rq->timeout = 0;
 188
 189         rq->end_io = NULL;
 190         rq->end_io_data = NULL;
 191         rq->next_rq = NULL;
 192
 193         ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
 194 }
 195
 196 static struct request *
 197 __blk_mq_alloc_request(struct blk_mq_alloc_data *data, int rw)
 198 {
 199         struct request *rq;
 200         unsigned int tag;
 201
 202         tag = blk_mq_get_tag(data);
 203         if (tag != BLK_MQ_TAG_FAIL) {
 204                 rq = data->hctx->tags->rqs[tag];
 205
 206                 if (blk_mq_tag_busy(data->hctx)) {
 207                         rq->cmd_flags = REQ_MQ_INFLIGHT;
 208                         atomic_inc(&data->hctx->nr_active);
 209                 }
 210
 211                 rq->tag = tag;
 212                 blk_mq_rq_ctx_init(data->q, data->ctx, rq, rw);
 213                 return rq;
 214         }
 215
 216         return NULL;
 217 }
 218
 219 struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp,
 220                 bool reserved)
 221 {
 222         struct blk_mq_ctx *ctx;
 223         struct blk_mq_hw_ctx *hctx;
 224         struct request *rq;
 225         struct blk_mq_alloc_data alloc_data;
 226
 227         if (blk_mq_queue_enter(q))
 228                 return NULL;
 229
 230         ctx = blk_mq_get_ctx(q);
 231         hctx = q->mq_ops->map_queue(q, ctx->cpu);
 232         blk_mq_set_alloc_data(&alloc_data, q, gfp & ~__GFP_WAIT,
 233                         reserved, ctx, hctx);
 234
 235         rq = __blk_mq_alloc_request(&alloc_data, rw);
 236         if (!rq && (gfp & __GFP_WAIT)) {
 237                 __blk_mq_run_hw_queue(hctx);
 238                 blk_mq_put_ctx(ctx);
 239
 240                 ctx = blk_mq_get_ctx(q);
 241                 hctx = q->mq_ops->map_queue(q, ctx->cpu);
 242                 blk_mq_set_alloc_data(&alloc_data, q, gfp, reserved, ctx,
 243                                 hctx);
 244                 rq =  __blk_mq_alloc_request(&alloc_data, rw);
 245                 ctx = alloc_data.ctx;
 246         }
 247         blk_mq_put_ctx(ctx);
 248         return rq;
 249 }
 250 EXPORT_SYMBOL(blk_mq_alloc_request);
 251
 252 static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
 253                                   struct blk_mq_ctx *ctx, struct request *rq)
 254 {
 255         const int tag = rq->tag;
 256         struct request_queue *q = rq->q;
 257
 258         if (rq->cmd_flags & REQ_MQ_INFLIGHT)
 259                 atomic_dec(&hctx->nr_active);
 260         rq->cmd_flags = 0;
 261
 262         clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 263         blk_mq_put_tag(hctx, tag, &ctx->last_tag);
 264         blk_mq_queue_exit(q);
 265 }
 266
 267 void blk_mq_free_request(struct request *rq)
 268 {
 269         struct blk_mq_ctx *ctx = rq->mq_ctx;
 270         struct blk_mq_hw_ctx *hctx;
 271         struct request_queue *q = rq->q;
 272
 273         ctx->rq_completed[rq_is_sync(rq)]++;
 274
 275         hctx = q->mq_ops->map_queue(q, ctx->cpu);
 276         __blk_mq_free_request(hctx, ctx, rq);
 277 }
 278
 279 /*
 280  * Clone all relevant state from a request that has been put on hold in
 281  * the flush state machine into the preallocated flush request that hangs
 282  * off the request queue.
 283  *
 284  * For a driver the flush request should be invisible, that's why we are
 285  * impersonating the original request here.
 286  */
 287 void blk_mq_clone_flush_request(struct request *flush_rq,
 288                 struct request *orig_rq)
 289 {
 290         struct blk_mq_hw_ctx *hctx =
 291                 orig_rq->q->mq_ops->map_queue(orig_rq->q, orig_rq->mq_ctx->cpu);
 292
 293         flush_rq->mq_ctx = orig_rq->mq_ctx;
 294         flush_rq->tag = orig_rq->tag;
 295         memcpy(blk_mq_rq_to_pdu(flush_rq), blk_mq_rq_to_pdu(orig_rq),
 296                 hctx->cmd_size);
 297 }
 298
 299 inline void __blk_mq_end_io(struct request *rq, int error)
 300 {
 301         blk_account_io_done(rq);
 302
 303         if (rq->end_io) {
 304                 rq->end_io(rq, error);
 305         } else {
 306                 if (unlikely(blk_bidi_rq(rq)))
 307                         blk_mq_free_request(rq->next_rq);
 308                 blk_mq_free_request(rq);
 309         }
 310 }
 311 EXPORT_SYMBOL(__blk_mq_end_io);
 312
 313 void blk_mq_end_io(struct request *rq, int error)
 314 {
 315         if (blk_update_request(rq, error, blk_rq_bytes(rq)))
 316                 BUG();
 317         __blk_mq_end_io(rq, error);
 318 }
 319 EXPORT_SYMBOL(blk_mq_end_io);
 320
 321 static void __blk_mq_complete_request_remote(void *data)
 322 {
 323         struct request *rq = data;
 324
 325         rq->q->softirq_done_fn(rq);
 326 }
 327
 328 static void blk_mq_ipi_complete_request(struct request *rq)
 329 {
 330         struct blk_mq_ctx *ctx = rq->mq_ctx;
 331         bool shared = false;
 332         int cpu;
 333
 334         if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
 335                 rq->q->softirq_done_fn(rq);
 336                 return;
 337         }
 338
 339         cpu = get_cpu();
 340         if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
 341                 shared = cpus_share_cache(cpu, ctx->cpu);
 342
 343         if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
 344                 rq->csd.func = __blk_mq_complete_request_remote;
 345                 rq->csd.info = rq;
 346                 rq->csd.flags = 0;
 347                 smp_call_function_single_async(ctx->cpu, &rq->csd);
 348         } else {
 349                 rq->q->softirq_done_fn(rq);
 350         }
 351         put_cpu();
 352 }
 353
 354 void __blk_mq_complete_request(struct request *rq)
 355 {
 356         struct request_queue *q = rq->q;
 357
 358         if (!q->softirq_done_fn)
 359                 blk_mq_end_io(rq, rq->errors);
 360         else
 361                 blk_mq_ipi_complete_request(rq);
 362 }
 363
 364 /**
 365  * blk_mq_complete_request - end I/O on a request
 366  * @rq:         the request being processed
 367  *
 368  * Description:
 369  *      Ends all I/O on a request. It does not handle partial completions.
 370  *      The actual completion happens out-of-order, through a IPI handler.
 371  **/
 372 void blk_mq_complete_request(struct request *rq)
 373 {
 374         struct request_queue *q = rq->q;
 375
 376         if (unlikely(blk_should_fake_timeout(q)))
 377                 return;
 378         if (!blk_mark_rq_complete(rq))
 379                 __blk_mq_complete_request(rq);
 380 }
 381 EXPORT_SYMBOL(blk_mq_complete_request);
 382
 383 static void blk_mq_start_request(struct request *rq, bool last)
 384 {
 385         struct request_queue *q = rq->q;
 386
 387         trace_block_rq_issue(q, rq);
 388
 389         rq->resid_len = blk_rq_bytes(rq);
 390         if (unlikely(blk_bidi_rq(rq)))
 391                 rq->next_rq->resid_len = blk_rq_bytes(rq->next_rq);
 392
 393         blk_add_timer(rq);
 394
 395         /*
 396          * Ensure that ->deadline is visible before set the started
 397          * flag and clear the completed flag.
 398          */
 399         smp_mb__before_atomic();
 400
 401         /*
 402          * Mark us as started and clear complete. Complete might have been
 403          * set if requeue raced with timeout, which then marked it as
 404          * complete. So be sure to clear complete again when we start
 405          * the request, otherwise we'll ignore the completion event.
 406          */
 407         if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
 408                 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 409         if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
 410                 clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
 411
 412         if (q->dma_drain_size && blk_rq_bytes(rq)) {
 413                 /*
 414                  * Make sure space for the drain appears.  We know we can do
 415                  * this because max_hw_segments has been adjusted to be one
 416                  * fewer than the device can handle.
 417                  */
 418                 rq->nr_phys_segments++;
 419         }
 420
 421         /*
 422          * Flag the last request in the series so that drivers know when IO
 423          * should be kicked off, if they don't do it on a per-request basis.
 424          *
 425          * Note: the flag isn't the only condition drivers should do kick off.
 426          * If drive is busy, the last request might not have the bit set.
 427          */
 428         if (last)
 429                 rq->cmd_flags |= REQ_END;
 430 }
 431
 432 static void __blk_mq_requeue_request(struct request *rq)
 433 {
 434         struct request_queue *q = rq->q;
 435
 436         trace_block_rq_requeue(q, rq);
 437         clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 438
 439         rq->cmd_flags &= ~REQ_END;
 440
 441         if (q->dma_drain_size && blk_rq_bytes(rq))
 442                 rq->nr_phys_segments--;
 443 }
 444
 445 void blk_mq_requeue_request(struct request *rq)
 446 {
 447         __blk_mq_requeue_request(rq);
 448         blk_clear_rq_complete(rq);
 449
 450         BUG_ON(blk_queued_rq(rq));
 451         blk_mq_add_to_requeue_list(rq, true);
 452 }
 453 EXPORT_SYMBOL(blk_mq_requeue_request);
 454
 455 static void blk_mq_requeue_work(struct work_struct *work)
 456 {
 457         struct request_queue *q =
 458                 container_of(work, struct request_queue, requeue_work);
 459         LIST_HEAD(rq_list);
 460         struct request *rq, *next;
 461         unsigned long flags;
 462
 463         spin_lock_irqsave(&q->requeue_lock, flags);
 464         list_splice_init(&q->requeue_list, &rq_list);
 465         spin_unlock_irqrestore(&q->requeue_lock, flags);
 466
 467         list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
 468                 if (!(rq->cmd_flags & REQ_SOFTBARRIER))
 469                         continue;
 470
 471                 rq->cmd_flags &= ~REQ_SOFTBARRIER;
 472                 list_del_init(&rq->queuelist);
 473                 blk_mq_insert_request(rq, true, false, false);
 474         }
 475
 476         while (!list_empty(&rq_list)) {
 477                 rq = list_entry(rq_list.next, struct request, queuelist);
 478                 list_del_init(&rq->queuelist);
 479                 blk_mq_insert_request(rq, false, false, false);
 480         }
 481
 482         blk_mq_run_queues(q, false);
 483 }
 484
 485 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head)
 486 {
 487         struct request_queue *q = rq->q;
 488         unsigned long flags;
 489
 490         /*
 491          * We abuse this flag that is otherwise used by the I/O scheduler to
 492          * request head insertation from the workqueue.
 493          */
 494         BUG_ON(rq->cmd_flags & REQ_SOFTBARRIER);
 495
 496         spin_lock_irqsave(&q->requeue_lock, flags);
 497         if (at_head) {
 498                 rq->cmd_flags |= REQ_SOFTBARRIER;
 499                 list_add(&rq->queuelist, &q->requeue_list);
 500         } else {
 501                 list_add_tail(&rq->queuelist, &q->requeue_list);
 502         }
 503         spin_unlock_irqrestore(&q->requeue_lock, flags);
 504 }
 505 EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
 506
 507 void blk_mq_kick_requeue_list(struct request_queue *q)
 508 {
 509         kblockd_schedule_work(&q->requeue_work);
 510 }
 511 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
 512
 513 static inline bool is_flush_request(struct request *rq, unsigned int tag)
 514 {
 515         return ((rq->cmd_flags & REQ_FLUSH_SEQ) &&
 516                         rq->q->flush_rq->tag == tag);
 517 }
 518
 519 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
 520 {
 521         struct request *rq = tags->rqs[tag];
 522
 523         if (!is_flush_request(rq, tag))
 524                 return rq;
 525
 526         return rq->q->flush_rq;
 527 }
 528 EXPORT_SYMBOL(blk_mq_tag_to_rq);
 529
 530 struct blk_mq_timeout_data {
 531         struct blk_mq_hw_ctx *hctx;
 532         unsigned long *next;
 533         unsigned int *next_set;
 534 };
 535
 536 static void blk_mq_timeout_check(void *__data, unsigned long *free_tags)
 537 {
 538         struct blk_mq_timeout_data *data = __data;
 539         struct blk_mq_hw_ctx *hctx = data->hctx;
 540         unsigned int tag;
 541
 542          /* It may not be in flight yet (this is where
 543          * the REQ_ATOMIC_STARTED flag comes in). The requests are
 544          * statically allocated, so we know it's always safe to access the
 545          * memory associated with a bit offset into ->rqs[].
 546          */
 547         tag = 0;
 548         do {
 549                 struct request *rq;
 550
 551                 tag = find_next_zero_bit(free_tags, hctx->tags->nr_tags, tag);
 552                 if (tag >= hctx->tags->nr_tags)
 553                         break;
 554
 555                 rq = blk_mq_tag_to_rq(hctx->tags, tag++);
 556                 if (rq->q != hctx->queue)
 557                         continue;
 558                 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
 559                         continue;
 560
 561                 blk_rq_check_expired(rq, data->next, data->next_set);
 562         } while (1);
 563 }
 564
 565 static void blk_mq_hw_ctx_check_timeout(struct blk_mq_hw_ctx *hctx,
 566                                         unsigned long *next,
 567                                         unsigned int *next_set)
 568 {
 569         struct blk_mq_timeout_data data = {
 570                 .hctx           = hctx,
 571                 .next           = next,
 572                 .next_set       = next_set,
 573         };
 574
 575         /*
 576          * Ask the tagging code to iterate busy requests, so we can
 577          * check them for timeout.
 578          */
 579         blk_mq_tag_busy_iter(hctx->tags, blk_mq_timeout_check, &data);
 580 }
 581
 582 static enum blk_eh_timer_return blk_mq_rq_timed_out(struct request *rq)
 583 {
 584         struct request_queue *q = rq->q;
 585
 586         /*
 587          * We know that complete is set at this point. If STARTED isn't set
 588          * anymore, then the request isn't active and the "timeout" should
 589          * just be ignored. This can happen due to the bitflag ordering.
 590          * Timeout first checks if STARTED is set, and if it is, assumes
 591          * the request is active. But if we race with completion, then
 592          * we both flags will get cleared. So check here again, and ignore
 593          * a timeout event with a request that isn't active.
 594          */
 595         if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
 596                 return BLK_EH_NOT_HANDLED;
 597
 598         if (!q->mq_ops->timeout)
 599                 return BLK_EH_RESET_TIMER;
 600
 601         return q->mq_ops->timeout(rq);
 602 }
 603
 604 static void blk_mq_rq_timer(unsigned long data)
 605 {
 606         struct request_queue *q = (struct request_queue *) data;
 607         struct blk_mq_hw_ctx *hctx;
 608         unsigned long next = 0;
 609         int i, next_set = 0;
 610
 611         queue_for_each_hw_ctx(q, hctx, i) {
 612                 /*
 613                  * If not software queues are currently mapped to this
 614                  * hardware queue, there's nothing to check
 615                  */
 616                 if (!hctx->nr_ctx || !hctx->tags)
 617                         continue;
 618
 619                 blk_mq_hw_ctx_check_timeout(hctx, &next, &next_set);
 620         }
 621
 622         if (next_set) {
 623                 next = blk_rq_timeout(round_jiffies_up(next));
 624                 mod_timer(&q->timeout, next);
 625         } else {
 626                 queue_for_each_hw_ctx(q, hctx, i)
 627                         blk_mq_tag_idle(hctx);
 628         }
 629 }
 630
 631 /*
 632  * Reverse check our software queue for entries that we could potentially
 633  * merge with. Currently includes a hand-wavy stop count of 8, to not spend
 634  * too much time checking for merges.
 635  */
 636 static bool blk_mq_attempt_merge(struct request_queue *q,
 637                                  struct blk_mq_ctx *ctx, struct bio *bio)
 638 {
 639         struct request *rq;
 640         int checked = 8;
 641
 642         list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
 643                 int el_ret;
 644
 645                 if (!checked--)
 646                         break;
 647
 648                 if (!blk_rq_merge_ok(rq, bio))
 649                         continue;
 650
 651                 el_ret = blk_try_merge(rq, bio);
 652                 if (el_ret == ELEVATOR_BACK_MERGE) {
 653                         if (bio_attempt_back_merge(q, rq, bio)) {
 654                                 ctx->rq_merged++;
 655                                 return true;
 656                         }
 657                         break;
 658                 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
 659                         if (bio_attempt_front_merge(q, rq, bio)) {
 660                                 ctx->rq_merged++;
 661                                 return true;
 662                         }
 663                         break;
 664                 }
 665         }
 666
 667         return false;
 668 }
 669
 670 /*
 671  * Process software queues that have been marked busy, splicing them
 672  * to the for-dispatch
 673  */
 674 static void flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
 675 {
 676         struct blk_mq_ctx *ctx;
 677         int i;
 678
 679         for (i = 0; i < hctx->ctx_map.map_size; i++) {
 680                 struct blk_align_bitmap *bm = &hctx->ctx_map.map[i];
 681                 unsigned int off, bit;
 682
 683                 if (!bm->word)
 684                         continue;
 685
 686                 bit = 0;
 687                 off = i * hctx->ctx_map.bits_per_word;
 688                 do {
 689                         bit = find_next_bit(&bm->word, bm->depth, bit);
 690                         if (bit >= bm->depth)
 691                                 break;
 692
 693                         ctx = hctx->ctxs[bit + off];
 694                         clear_bit(bit, &bm->word);
 695                         spin_lock(&ctx->lock);
 696                         list_splice_tail_init(&ctx->rq_list, list);
 697                         spin_unlock(&ctx->lock);
 698
 699                         bit++;
 700                 } while (1);
 701         }
 702 }
 703
 704 /*
 705  * Run this hardware queue, pulling any software queues mapped to it in.
 706  * Note that this function currently has various problems around ordering
 707  * of IO. In particular, we'd like FIFO behaviour on handling existing
 708  * items on the hctx->dispatch list. Ignore that for now.
 709  */
 710 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
 711 {
 712         struct request_queue *q = hctx->queue;
 713         struct request *rq;
 714         LIST_HEAD(rq_list);
 715         int queued;
 716
 717         WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask));
 718
 719         if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
 720                 return;
 721
 722         hctx->run++;
 723
 724         /*
 725          * Touch any software queue that has pending entries.
 726          */
 727         flush_busy_ctxs(hctx, &rq_list);
 728
 729         /*
 730          * If we have previous entries on our dispatch list, grab them
 731          * and stuff them at the front for more fair dispatch.
 732          */
 733         if (!list_empty_careful(&hctx->dispatch)) {
 734                 spin_lock(&hctx->lock);
 735                 if (!list_empty(&hctx->dispatch))
 736                         list_splice_init(&hctx->dispatch, &rq_list);
 737                 spin_unlock(&hctx->lock);
 738         }
 739
 740         /*
 741          * Now process all the entries, sending them to the driver.
 742          */
 743         queued = 0;
 744         while (!list_empty(&rq_list)) {
 745                 int ret;
 746
 747                 rq = list_first_entry(&rq_list, struct request, queuelist);
 748                 list_del_init(&rq->queuelist);
 749
 750                 blk_mq_start_request(rq, list_empty(&rq_list));
 751
 752                 ret = q->mq_ops->queue_rq(hctx, rq);
 753                 switch (ret) {
 754                 case BLK_MQ_RQ_QUEUE_OK:
 755                         queued++;
 756                         continue;
 757                 case BLK_MQ_RQ_QUEUE_BUSY:
 758                         list_add(&rq->queuelist, &rq_list);
 759                         __blk_mq_requeue_request(rq);
 760                         break;
 761                 default:
 762                         pr_err("blk-mq: bad return on queue: %d\n", ret);
 763                 case BLK_MQ_RQ_QUEUE_ERROR:
 764                         rq->errors = -EIO;
 765                         blk_mq_end_io(rq, rq->errors);
 766                         break;
 767                 }
 768
 769                 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
 770                         break;
 771         }
 772
 773         if (!queued)
 774                 hctx->dispatched[0]++;
 775         else if (queued < (1 << (BLK_MQ_MAX_DISPATCH_ORDER - 1)))
 776                 hctx->dispatched[ilog2(queued) + 1]++;
 777
 778         /*
 779          * Any items that need requeuing? Stuff them into hctx->dispatch,
 780          * that is where we will continue on next queue run.
 781          */
 782         if (!list_empty(&rq_list)) {
 783                 spin_lock(&hctx->lock);
 784                 list_splice(&rq_list, &hctx->dispatch);
 785                 spin_unlock(&hctx->lock);
 786         }
 787 }
 788
 789 /*
 790  * It'd be great if the workqueue API had a way to pass
 791  * in a mask and had some smarts for more clever placement.
 792  * For now we just round-robin here, switching for every
 793  * BLK_MQ_CPU_WORK_BATCH queued items.
 794  */
 795 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
 796 {
 797         int cpu = hctx->next_cpu;
 798
 799         if (--hctx->next_cpu_batch <= 0) {
 800                 int next_cpu;
 801
 802                 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
 803                 if (next_cpu >= nr_cpu_ids)
 804                         next_cpu = cpumask_first(hctx->cpumask);
 805
 806                 hctx->next_cpu = next_cpu;
 807                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
 808         }
 809
 810         return cpu;
 811 }
 812
 813 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
 814 {
 815         if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
 816                 return;
 817
 818         if (!async && cpumask_test_cpu(smp_processor_id(), hctx->cpumask))
 819                 __blk_mq_run_hw_queue(hctx);
 820         else if (hctx->queue->nr_hw_queues == 1)
 821                 kblockd_schedule_delayed_work(&hctx->run_work, 0);
 822         else {
 823                 unsigned int cpu;
 824
 825                 cpu = blk_mq_hctx_next_cpu(hctx);
 826                 kblockd_schedule_delayed_work_on(cpu, &hctx->run_work, 0);
 827         }
 828 }
 829
 830 void blk_mq_run_queues(struct request_queue *q, bool async)
 831 {
 832         struct blk_mq_hw_ctx *hctx;
 833         int i;
 834
 835         queue_for_each_hw_ctx(q, hctx, i) {
 836                 if ((!blk_mq_hctx_has_pending(hctx) &&
 837                     list_empty_careful(&hctx->dispatch)) ||
 838                     test_bit(BLK_MQ_S_STOPPED, &hctx->state))
 839                         continue;
 840
 841                 preempt_disable();
 842                 blk_mq_run_hw_queue(hctx, async);
 843                 preempt_enable();
 844         }
 845 }
 846 EXPORT_SYMBOL(blk_mq_run_queues);
 847
 848 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
 849 {
 850         cancel_delayed_work(&hctx->run_work);
 851         cancel_delayed_work(&hctx->delay_work);
 852         set_bit(BLK_MQ_S_STOPPED, &hctx->state);
 853 }
 854 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
 855
 856 void blk_mq_stop_hw_queues(struct request_queue *q)
 857 {
 858         struct blk_mq_hw_ctx *hctx;
 859         int i;
 860
 861         queue_for_each_hw_ctx(q, hctx, i)
 862                 blk_mq_stop_hw_queue(hctx);
 863 }
 864 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
 865
 866 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
 867 {
 868         clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
 869
 870         preempt_disable();
 871         blk_mq_run_hw_queue(hctx, false);
 872         preempt_enable();
 873 }
 874 EXPORT_SYMBOL(blk_mq_start_hw_queue);
 875
 876 void blk_mq_start_hw_queues(struct request_queue *q)
 877 {
 878         struct blk_mq_hw_ctx *hctx;
 879         int i;
 880
 881         queue_for_each_hw_ctx(q, hctx, i)
 882                 blk_mq_start_hw_queue(hctx);
 883 }
 884 EXPORT_SYMBOL(blk_mq_start_hw_queues);
 885
 886
 887 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
 888 {
 889         struct blk_mq_hw_ctx *hctx;
 890         int i;
 891
 892         queue_for_each_hw_ctx(q, hctx, i) {
 893                 if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
 894                         continue;
 895
 896                 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
 897                 preempt_disable();
 898                 blk_mq_run_hw_queue(hctx, async);
 899                 preempt_enable();
 900         }
 901 }
 902 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
 903
 904 static void blk_mq_run_work_fn(struct work_struct *work)
 905 {
 906         struct blk_mq_hw_ctx *hctx;
 907
 908         hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
 909
 910         __blk_mq_run_hw_queue(hctx);
 911 }
 912
 913 static void blk_mq_delay_work_fn(struct work_struct *work)
 914 {
 915         struct blk_mq_hw_ctx *hctx;
 916
 917         hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
 918
 919         if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
 920                 __blk_mq_run_hw_queue(hctx);
 921 }
 922
 923 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
 924 {
 925         unsigned long tmo = msecs_to_jiffies(msecs);
 926
 927         if (hctx->queue->nr_hw_queues == 1)
 928                 kblockd_schedule_delayed_work(&hctx->delay_work, tmo);
 929         else {
 930                 unsigned int cpu;
 931
 932                 cpu = blk_mq_hctx_next_cpu(hctx);
 933                 kblockd_schedule_delayed_work_on(cpu, &hctx->delay_work, tmo);
 934         }
 935 }
 936 EXPORT_SYMBOL(blk_mq_delay_queue);
 937
 938 static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
 939                                     struct request *rq, bool at_head)
 940 {
 941         struct blk_mq_ctx *ctx = rq->mq_ctx;
 942
 943         trace_block_rq_insert(hctx->queue, rq);
 944
 945         if (at_head)
 946                 list_add(&rq->queuelist, &ctx->rq_list);
 947         else
 948                 list_add_tail(&rq->queuelist, &ctx->rq_list);
 949
 950         blk_mq_hctx_mark_pending(hctx, ctx);
 951 }
 952
 953 void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
 954                 bool async)
 955 {
 956         struct request_queue *q = rq->q;
 957         struct blk_mq_hw_ctx *hctx;
 958         struct blk_mq_ctx *ctx = rq->mq_ctx, *current_ctx;
 959
 960         current_ctx = blk_mq_get_ctx(q);
 961         if (!cpu_online(ctx->cpu))
 962                 rq->mq_ctx = ctx = current_ctx;
 963
 964         hctx = q->mq_ops->map_queue(q, ctx->cpu);
 965
 966         spin_lock(&ctx->lock);
 967         __blk_mq_insert_request(hctx, rq, at_head);
 968         spin_unlock(&ctx->lock);
 969
 970         if (run_queue)
 971                 blk_mq_run_hw_queue(hctx, async);
 972
 973         blk_mq_put_ctx(current_ctx);
 974 }
 975
 976 static void blk_mq_insert_requests(struct request_queue *q,
 977                                      struct blk_mq_ctx *ctx,
 978                                      struct list_head *list,
 979                                      int depth,
 980                                      bool from_schedule)
 981
 982 {
 983         struct blk_mq_hw_ctx *hctx;
 984         struct blk_mq_ctx *current_ctx;
 985
 986         trace_block_unplug(q, depth, !from_schedule);
 987
 988         current_ctx = blk_mq_get_ctx(q);
 989
 990         if (!cpu_online(ctx->cpu))
 991                 ctx = current_ctx;
 992         hctx = q->mq_ops->map_queue(q, ctx->cpu);
 993
 994         /*
 995          * preemption doesn't flush plug list, so it's possible ctx->cpu is
 996          * offline now
 997          */
 998         spin_lock(&ctx->lock);
 999         while (!list_empty(list)) {
1000                 struct request *rq;
1001
1002                 rq = list_first_entry(list, struct request, queuelist);
1003                 list_del_init(&rq->queuelist);
1004                 rq->mq_ctx = ctx;
1005                 __blk_mq_insert_request(hctx, rq, false);
1006         }
1007         spin_unlock(&ctx->lock);
1008
1009         blk_mq_run_hw_queue(hctx, from_schedule);
1010         blk_mq_put_ctx(current_ctx);
1011 }
1012
1013 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1014 {
1015         struct request *rqa = container_of(a, struct request, queuelist);
1016         struct request *rqb = container_of(b, struct request, queuelist);
1017
1018         return !(rqa->mq_ctx < rqb->mq_ctx ||
1019                  (rqa->mq_ctx == rqb->mq_ctx &&
1020                   blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1021 }
1022
1023 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1024 {
1025         struct blk_mq_ctx *this_ctx;
1026         struct request_queue *this_q;
1027         struct request *rq;
1028         LIST_HEAD(list);
1029         LIST_HEAD(ctx_list);
1030         unsigned int depth;
1031
1032         list_splice_init(&plug->mq_list, &list);
1033
1034         list_sort(NULL, &list, plug_ctx_cmp);
1035
1036         this_q = NULL;
1037         this_ctx = NULL;
1038         depth = 0;
1039
1040         while (!list_empty(&list)) {
1041                 rq = list_entry_rq(list.next);
1042                 list_del_init(&rq->queuelist);
1043                 BUG_ON(!rq->q);
1044                 if (rq->mq_ctx != this_ctx) {
1045                         if (this_ctx) {
1046                                 blk_mq_insert_requests(this_q, this_ctx,
1047                                                         &ctx_list, depth,
1048                                                         from_schedule);
1049                         }
1050
1051                         this_ctx = rq->mq_ctx;
1052                         this_q = rq->q;
1053                         depth = 0;
1054                 }
1055
1056                 depth++;
1057                 list_add_tail(&rq->queuelist, &ctx_list);
1058         }
1059
1060         /*
1061          * If 'this_ctx' is set, we know we have entries to complete
1062          * on 'ctx_list'. Do those.
1063          */
1064         if (this_ctx) {
1065                 blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
1066                                        from_schedule);
1067         }
1068 }
1069
1070 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1071 {
1072         init_request_from_bio(rq, bio);
1073
1074         if (blk_do_io_stat(rq))
1075                 blk_account_io_start(rq, 1);
1076 }
1077
1078 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
1079 {
1080         return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
1081                 !blk_queue_nomerges(hctx->queue);
1082 }
1083
1084 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
1085                                          struct blk_mq_ctx *ctx,
1086                                          struct request *rq, struct bio *bio)
1087 {
1088         if (!hctx_allow_merges(hctx)) {
1089                 blk_mq_bio_to_request(rq, bio);
1090                 spin_lock(&ctx->lock);
1091 insert_rq:
1092                 __blk_mq_insert_request(hctx, rq, false);
1093                 spin_unlock(&ctx->lock);
1094                 return false;
1095         } else {
1096                 struct request_queue *q = hctx->queue;
1097
1098                 spin_lock(&ctx->lock);
1099                 if (!blk_mq_attempt_merge(q, ctx, bio)) {
1100                         blk_mq_bio_to_request(rq, bio);
1101                         goto insert_rq;
1102                 }
1103
1104                 spin_unlock(&ctx->lock);
1105                 __blk_mq_free_request(hctx, ctx, rq);
1106                 return true;
1107         }
1108 }
1109
1110 struct blk_map_ctx {
1111         struct blk_mq_hw_ctx *hctx;
1112         struct blk_mq_ctx *ctx;
1113 };
1114
1115 static struct request *blk_mq_map_request(struct request_queue *q,
1116                                           struct bio *bio,
1117                                           struct blk_map_ctx *data)
1118 {
1119         struct blk_mq_hw_ctx *hctx;
1120         struct blk_mq_ctx *ctx;
1121         struct request *rq;
1122         int rw = bio_data_dir(bio);
1123         struct blk_mq_alloc_data alloc_data;
1124
1125         if (unlikely(blk_mq_queue_enter(q))) {
1126                 bio_endio(bio, -EIO);
1127                 return NULL;
1128         }
1129
1130         ctx = blk_mq_get_ctx(q);
1131         hctx = q->mq_ops->map_queue(q, ctx->cpu);
1132
1133         if (rw_is_sync(bio->bi_rw))
1134                 rw |= REQ_SYNC;
1135
1136         trace_block_getrq(q, bio, rw);
1137         blk_mq_set_alloc_data(&alloc_data, q, GFP_ATOMIC, false, ctx,
1138                         hctx);
1139         rq = __blk_mq_alloc_request(&alloc_data, rw);
1140         if (unlikely(!rq)) {
1141                 __blk_mq_run_hw_queue(hctx);
1142                 blk_mq_put_ctx(ctx);
1143                 trace_block_sleeprq(q, bio, rw);
1144
1145                 ctx = blk_mq_get_ctx(q);
1146                 hctx = q->mq_ops->map_queue(q, ctx->cpu);
1147                 blk_mq_set_alloc_data(&alloc_data, q,
1148                                 __GFP_WAIT|GFP_ATOMIC, false, ctx, hctx);
1149                 rq = __blk_mq_alloc_request(&alloc_data, rw);
1150                 ctx = alloc_data.ctx;
1151                 hctx = alloc_data.hctx;
1152         }
1153
1154         hctx->queued++;
1155         data->hctx = hctx;
1156         data->ctx = ctx;
1157         return rq;
1158 }
1159
1160 /*
1161  * Multiple hardware queue variant. This will not use per-process plugs,
1162  * but will attempt to bypass the hctx queueing if we can go straight to
1163  * hardware for SYNC IO.
1164  */
1165 static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
1166 {
1167         const int is_sync = rw_is_sync(bio->bi_rw);
1168         const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
1169         struct blk_map_ctx data;
1170         struct request *rq;
1171
1172         blk_queue_bounce(q, &bio);
1173
1174         if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1175                 bio_endio(bio, -EIO);
1176                 return;
1177         }
1178
1179         rq = blk_mq_map_request(q, bio, &data);
1180         if (unlikely(!rq))
1181                 return;
1182
1183         if (unlikely(is_flush_fua)) {
1184                 blk_mq_bio_to_request(rq, bio);
1185                 blk_insert_flush(rq);
1186                 goto run_queue;
1187         }
1188
1189         if (is_sync) {
1190                 int ret;
1191
1192                 blk_mq_bio_to_request(rq, bio);
1193                 blk_mq_start_request(rq, true);
1194
1195                 /*
1196                  * For OK queue, we are done. For error, kill it. Any other
1197                  * error (busy), just add it to our list as we previously
1198                  * would have done
1199                  */
1200                 ret = q->mq_ops->queue_rq(data.hctx, rq);
1201                 if (ret == BLK_MQ_RQ_QUEUE_OK)
1202                         goto done;
1203                 else {
1204                         __blk_mq_requeue_request(rq);
1205
1206                         if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
1207                                 rq->errors = -EIO;
1208                                 blk_mq_end_io(rq, rq->errors);
1209                                 goto done;
1210                         }
1211                 }
1212         }
1213
1214         if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1215                 /*
1216                  * For a SYNC request, send it to the hardware immediately. For
1217                  * an ASYNC request, just ensure that we run it later on. The
1218                  * latter allows for merging opportunities and more efficient
1219                  * dispatching.
1220                  */
1221 run_queue:
1222                 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1223         }
1224 done:
1225         blk_mq_put_ctx(data.ctx);
1226 }
1227
1228 /*
1229  * Single hardware queue variant. This will attempt to use any per-process
1230  * plug for merging and IO deferral.
1231  */
1232 static void blk_sq_make_request(struct request_queue *q, struct bio *bio)
1233 {
1234         const int is_sync = rw_is_sync(bio->bi_rw);
1235         const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
1236         unsigned int use_plug, request_count = 0;
1237         struct blk_map_ctx data;
1238         struct request *rq;
1239
1240         /*
1241          * If we have multiple hardware queues, just go directly to
1242          * one of those for sync IO.
1243          */
1244         use_plug = !is_flush_fua && !is_sync;
1245
1246         blk_queue_bounce(q, &bio);
1247
1248         if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1249                 bio_endio(bio, -EIO);
1250                 return;
1251         }
1252
1253         if (use_plug && !blk_queue_nomerges(q) &&
1254             blk_attempt_plug_merge(q, bio, &request_count))
1255                 return;
1256
1257         rq = blk_mq_map_request(q, bio, &data);
1258         if (unlikely(!rq))
1259                 return;
1260
1261         if (unlikely(is_flush_fua)) {
1262                 blk_mq_bio_to_request(rq, bio);
1263                 blk_insert_flush(rq);
1264                 goto run_queue;
1265         }
1266
1267         /*
1268          * A task plug currently exists. Since this is completely lockless,
1269          * utilize that to temporarily store requests until the task is
1270          * either done or scheduled away.
1271          */
1272         if (use_plug) {
1273                 struct blk_plug *plug = current->plug;
1274
1275                 if (plug) {
1276                         blk_mq_bio_to_request(rq, bio);
1277                         if (list_empty(&plug->mq_list))
1278                                 trace_block_plug(q);
1279                         else if (request_count >= BLK_MAX_REQUEST_COUNT) {
1280                                 blk_flush_plug_list(plug, false);
1281                                 trace_block_plug(q);
1282                         }
1283                         list_add_tail(&rq->queuelist, &plug->mq_list);
1284                         blk_mq_put_ctx(data.ctx);
1285                         return;
1286                 }
1287         }
1288
1289         if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1290                 /*
1291                  * For a SYNC request, send it to the hardware immediately. For
1292                  * an ASYNC request, just ensure that we run it later on. The
1293                  * latter allows for merging opportunities and more efficient
1294                  * dispatching.
1295                  */
1296 run_queue:
1297                 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1298         }
1299
1300         blk_mq_put_ctx(data.ctx);
1301 }
1302
1303 /*
1304  * Default mapping to a software queue, since we use one per CPU.
1305  */
1306 struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q, const int cpu)
1307 {
1308         return q->queue_hw_ctx[q->mq_map[cpu]];
1309 }
1310 EXPORT_SYMBOL(blk_mq_map_queue);
1311
1312 static void blk_mq_free_rq_map(struct blk_mq_tag_set *set,
1313                 struct blk_mq_tags *tags, unsigned int hctx_idx)
1314 {
1315         struct page *page;
1316
1317         if (tags->rqs && set->ops->exit_request) {
1318                 int i;
1319
1320                 for (i = 0; i < tags->nr_tags; i++) {
1321                         if (!tags->rqs[i])
1322                                 continue;
1323                         set->ops->exit_request(set->driver_data, tags->rqs[i],
1324                                                 hctx_idx, i);
1325                         tags->rqs[i] = NULL;
1326                 }
1327         }
1328
1329         while (!list_empty(&tags->page_list)) {
1330                 page = list_first_entry(&tags->page_list, struct page, lru);
1331                 list_del_init(&page->lru);
1332                 __free_pages(page, page->private);
1333         }
1334
1335         kfree(tags->rqs);
1336
1337         blk_mq_free_tags(tags);
1338 }
1339
1340 static size_t order_to_size(unsigned int order)
1341 {
1342         return (size_t)PAGE_SIZE << order;
1343 }
1344
1345 static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
1346                 unsigned int hctx_idx)
1347 {
1348         struct blk_mq_tags *tags;
1349         unsigned int i, j, entries_per_page, max_order = 4;
1350         size_t rq_size, left;
1351
1352         tags = blk_mq_init_tags(set->queue_depth, set->reserved_tags,
1353                                 set->numa_node);
1354         if (!tags)
1355                 return NULL;
1356
1357         INIT_LIST_HEAD(&tags->page_list);
1358
1359         tags->rqs = kzalloc_node(set->queue_depth * sizeof(struct request *),
1360                                  GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
1361                                  set->numa_node);
1362         if (!tags->rqs) {
1363                 blk_mq_free_tags(tags);
1364                 return NULL;
1365         }
1366
1367         /*
1368          * rq_size is the size of the request plus driver payload, rounded
1369          * to the cacheline size
1370          */
1371         rq_size = round_up(sizeof(struct request) + set->cmd_size,
1372                                 cache_line_size());
1373         left = rq_size * set->queue_depth;
1374
1375         for (i = 0; i < set->queue_depth; ) {
1376                 int this_order = max_order;
1377                 struct page *page;
1378                 int to_do;
1379                 void *p;
1380
1381                 while (left < order_to_size(this_order - 1) && this_order)
1382                         this_order--;
1383
1384                 do {
1385                         page = alloc_pages_node(set->numa_node,
1386                                 GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
1387                                 this_order);
1388                         if (page)
1389                                 break;
1390                         if (!this_order--)
1391                                 break;
1392                         if (order_to_size(this_order) < rq_size)
1393                                 break;
1394                 } while (1);
1395
1396                 if (!page)
1397                         goto fail;
1398
1399                 page->private = this_order;
1400                 list_add_tail(&page->lru, &tags->page_list);
1401
1402                 p = page_address(page);
1403                 entries_per_page = order_to_size(this_order) / rq_size;
1404                 to_do = min(entries_per_page, set->queue_depth - i);
1405                 left -= to_do * rq_size;
1406                 for (j = 0; j < to_do; j++) {
1407                         tags->rqs[i] = p;
1408                         tags->rqs[i]->atomic_flags = 0;
1409                         tags->rqs[i]->cmd_flags = 0;
1410                         if (set->ops->init_request) {
1411                                 if (set->ops->init_request(set->driver_data,
1412                                                 tags->rqs[i], hctx_idx, i,
1413                                                 set->numa_node)) {
1414                                         tags->rqs[i] = NULL;
1415                                         goto fail;
1416                                 }
1417                         }
1418
1419                         p += rq_size;
1420                         i++;
1421                 }
1422         }
1423
1424         return tags;
1425
1426 fail:
1427         blk_mq_free_rq_map(set, tags, hctx_idx);
1428         return NULL;
1429 }
1430
1431 static void blk_mq_free_bitmap(struct blk_mq_ctxmap *bitmap)
1432 {
1433         kfree(bitmap->map);
1434 }
1435
1436 static int blk_mq_alloc_bitmap(struct blk_mq_ctxmap *bitmap, int node)
1437 {
1438         unsigned int bpw = 8, total, num_maps, i;
1439
1440         bitmap->bits_per_word = bpw;
1441
1442         num_maps = ALIGN(nr_cpu_ids, bpw) / bpw;
1443         bitmap->map = kzalloc_node(num_maps * sizeof(struct blk_align_bitmap),
1444                                         GFP_KERNEL, node);
1445         if (!bitmap->map)
1446                 return -ENOMEM;
1447
1448         bitmap->map_size = num_maps;
1449
1450         total = nr_cpu_ids;
1451         for (i = 0; i < num_maps; i++) {
1452                 bitmap->map[i].depth = min(total, bitmap->bits_per_word);
1453                 total -= bitmap->map[i].depth;
1454         }
1455
1456         return 0;
1457 }
1458
1459 static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx *hctx, int cpu)
1460 {
1461         struct request_queue *q = hctx->queue;
1462         struct blk_mq_ctx *ctx;
1463         LIST_HEAD(tmp);
1464
1465         /*
1466          * Move ctx entries to new CPU, if this one is going away.
1467          */
1468         ctx = __blk_mq_get_ctx(q, cpu);
1469
1470         spin_lock(&ctx->lock);
1471         if (!list_empty(&ctx->rq_list)) {
1472                 list_splice_init(&ctx->rq_list, &tmp);
1473                 blk_mq_hctx_clear_pending(hctx, ctx);
1474         }
1475         spin_unlock(&ctx->lock);
1476
1477         if (list_empty(&tmp))
1478                 return NOTIFY_OK;
1479
1480         ctx = blk_mq_get_ctx(q);
1481         spin_lock(&ctx->lock);
1482
1483         while (!list_empty(&tmp)) {
1484                 struct request *rq;
1485
1486                 rq = list_first_entry(&tmp, struct request, queuelist);
1487                 rq->mq_ctx = ctx;
1488                 list_move_tail(&rq->queuelist, &ctx->rq_list);
1489         }
1490
1491         hctx = q->mq_ops->map_queue(q, ctx->cpu);
1492         blk_mq_hctx_mark_pending(hctx, ctx);
1493
1494         spin_unlock(&ctx->lock);
1495
1496         blk_mq_run_hw_queue(hctx, true);
1497         blk_mq_put_ctx(ctx);
1498         return NOTIFY_OK;
1499 }
1500
1501 static int blk_mq_hctx_cpu_online(struct blk_mq_hw_ctx *hctx, int cpu)
1502 {
1503         struct request_queue *q = hctx->queue;
1504         struct blk_mq_tag_set *set = q->tag_set;
1505
1506         if (set->tags[hctx->queue_num])
1507                 return NOTIFY_OK;
1508
1509         set->tags[hctx->queue_num] = blk_mq_init_rq_map(set, hctx->queue_num);
1510         if (!set->tags[hctx->queue_num])
1511                 return NOTIFY_STOP;
1512
1513         hctx->tags = set->tags[hctx->queue_num];
1514         return NOTIFY_OK;
1515 }
1516
1517 static int blk_mq_hctx_notify(void *data, unsigned long action,
1518                               unsigned int cpu)
1519 {
1520         struct blk_mq_hw_ctx *hctx = data;
1521
1522         if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
1523                 return blk_mq_hctx_cpu_offline(hctx, cpu);
1524         else if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN)
1525                 return blk_mq_hctx_cpu_online(hctx, cpu);
1526
1527         return NOTIFY_OK;
1528 }
1529
1530 static void blk_mq_exit_hw_queues(struct request_queue *q,
1531                 struct blk_mq_tag_set *set, int nr_queue)
1532 {
1533         struct blk_mq_hw_ctx *hctx;
1534         unsigned int i;
1535
1536         queue_for_each_hw_ctx(q, hctx, i) {
1537                 if (i == nr_queue)
1538                         break;
1539
1540                 blk_mq_tag_idle(hctx);
1541
1542                 if (set->ops->exit_hctx)
1543                         set->ops->exit_hctx(hctx, i);
1544
1545                 blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1546                 kfree(hctx->ctxs);
1547                 blk_mq_free_bitmap(&hctx->ctx_map);
1548         }
1549
1550 }
1551
1552 static void blk_mq_free_hw_queues(struct request_queue *q,
1553                 struct blk_mq_tag_set *set)
1554 {
1555         struct blk_mq_hw_ctx *hctx;
1556         unsigned int i;
1557
1558         queue_for_each_hw_ctx(q, hctx, i) {
1559                 free_cpumask_var(hctx->cpumask);
1560                 kfree(hctx);
1561         }
1562 }
1563
1564 static int blk_mq_init_hw_queues(struct request_queue *q,
1565                 struct blk_mq_tag_set *set)
1566 {
1567         struct blk_mq_hw_ctx *hctx;
1568         unsigned int i;
1569
1570         /*
1571          * Initialize hardware queues
1572          */
1573         queue_for_each_hw_ctx(q, hctx, i) {
1574                 int node;
1575
1576                 node = hctx->numa_node;
1577                 if (node == NUMA_NO_NODE)
1578                         node = hctx->numa_node = set->numa_node;
1579
1580                 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
1581                 INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
1582                 spin_lock_init(&hctx->lock);
1583                 INIT_LIST_HEAD(&hctx->dispatch);
1584                 hctx->queue = q;
1585                 hctx->queue_num = i;
1586                 hctx->flags = set->flags;
1587                 hctx->cmd_size = set->cmd_size;
1588
1589                 blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
1590                                                 blk_mq_hctx_notify, hctx);
1591                 blk_mq_register_cpu_notifier(&hctx->cpu_notifier);
1592
1593                 hctx->tags = set->tags[i];
1594
1595                 /*
1596                  * Allocate space for all possible cpus to avoid allocation at
1597                  * runtime
1598                  */
1599                 hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1600                                                 GFP_KERNEL, node);
1601                 if (!hctx->ctxs)
1602                         break;
1603
1604                 if (blk_mq_alloc_bitmap(&hctx->ctx_map, node))
1605                         break;
1606
1607                 hctx->nr_ctx = 0;
1608
1609                 if (set->ops->init_hctx &&
1610                     set->ops->init_hctx(hctx, set->driver_data, i))
1611                         break;
1612         }
1613
1614         if (i == q->nr_hw_queues)
1615                 return 0;
1616
1617         /*
1618          * Init failed
1619          */
1620         blk_mq_exit_hw_queues(q, set, i);
1621
1622         return 1;
1623 }
1624
1625 static void blk_mq_init_cpu_queues(struct request_queue *q,
1626                                    unsigned int nr_hw_queues)
1627 {
1628         unsigned int i;
1629
1630         for_each_possible_cpu(i) {
1631                 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1632                 struct blk_mq_hw_ctx *hctx;
1633
1634                 memset(__ctx, 0, sizeof(*__ctx));
1635                 __ctx->cpu = i;
1636                 spin_lock_init(&__ctx->lock);
1637                 INIT_LIST_HEAD(&__ctx->rq_list);
1638                 __ctx->queue = q;
1639
1640                 /* If the cpu isn't online, the cpu is mapped to first hctx */
1641                 if (!cpu_online(i))
1642                         continue;
1643
1644                 hctx = q->mq_ops->map_queue(q, i);
1645                 cpumask_set_cpu(i, hctx->cpumask);
1646                 hctx->nr_ctx++;
1647
1648                 /*
1649                  * Set local node, IFF we have more than one hw queue. If
1650                  * not, we remain on the home node of the device
1651                  */
1652                 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
1653                         hctx->numa_node = cpu_to_node(i);
1654         }
1655 }
1656
1657 static void blk_mq_map_swqueue(struct request_queue *q)
1658 {
1659         unsigned int i;
1660         struct blk_mq_hw_ctx *hctx;
1661         struct blk_mq_ctx *ctx;
1662
1663         queue_for_each_hw_ctx(q, hctx, i) {
1664                 cpumask_clear(hctx->cpumask);
1665                 hctx->nr_ctx = 0;
1666         }
1667
1668         /*
1669          * Map software to hardware queues
1670          */
1671         queue_for_each_ctx(q, ctx, i) {
1672                 /* If the cpu isn't online, the cpu is mapped to first hctx */
1673                 if (!cpu_online(i))
1674                         continue;
1675
1676                 hctx = q->mq_ops->map_queue(q, i);
1677                 cpumask_set_cpu(i, hctx->cpumask);
1678                 ctx->index_hw = hctx->nr_ctx;
1679                 hctx->ctxs[hctx->nr_ctx++] = ctx;
1680         }
1681
1682         queue_for_each_hw_ctx(q, hctx, i) {
1683                 /*
1684                  * If no software queues are mapped to this hardware queue,
1685                  * disable it and free the request entries.
1686                  */
1687                 if (!hctx->nr_ctx) {
1688                         struct blk_mq_tag_set *set = q->tag_set;
1689
1690                         if (set->tags[i]) {
1691                                 blk_mq_free_rq_map(set, set->tags[i], i);
1692                                 set->tags[i] = NULL;
1693                                 hctx->tags = NULL;
1694                         }
1695                         continue;
1696                 }
1697
1698                 /*
1699                  * Initialize batch roundrobin counts
1700                  */
1701                 hctx->next_cpu = cpumask_first(hctx->cpumask);
1702                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1703         }
1704 }
1705
1706 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set)
1707 {
1708         struct blk_mq_hw_ctx *hctx;
1709         struct request_queue *q;
1710         bool shared;
1711         int i;
1712
1713         if (set->tag_list.next == set->tag_list.prev)
1714                 shared = false;
1715         else
1716                 shared = true;
1717
1718         list_for_each_entry(q, &set->tag_list, tag_set_list) {
1719                 blk_mq_freeze_queue(q);
1720
1721                 queue_for_each_hw_ctx(q, hctx, i) {
1722                         if (shared)
1723                                 hctx->flags |= BLK_MQ_F_TAG_SHARED;
1724                         else
1725                                 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
1726                 }
1727                 blk_mq_unfreeze_queue(q);
1728         }
1729 }
1730
1731 static void blk_mq_del_queue_tag_set(struct request_queue *q)
1732 {
1733         struct blk_mq_tag_set *set = q->tag_set;
1734
1735         mutex_lock(&set->tag_list_lock);
1736         list_del_init(&q->tag_set_list);
1737         blk_mq_update_tag_set_depth(set);
1738         mutex_unlock(&set->tag_list_lock);
1739 }
1740
1741 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
1742                                      struct request_queue *q)
1743 {
1744         q->tag_set = set;
1745
1746         mutex_lock(&set->tag_list_lock);
1747         list_add_tail(&q->tag_set_list, &set->tag_list);
1748         blk_mq_update_tag_set_depth(set);
1749         mutex_unlock(&set->tag_list_lock);
1750 }
1751
1752 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
1753 {
1754         struct blk_mq_hw_ctx **hctxs;
1755         struct blk_mq_ctx __percpu *ctx;
1756         struct request_queue *q;
1757         unsigned int *map;
1758         int i;
1759
1760         ctx = alloc_percpu(struct blk_mq_ctx);
1761         if (!ctx)
1762                 return ERR_PTR(-ENOMEM);
1763
1764         hctxs = kmalloc_node(set->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
1765                         set->numa_node);
1766
1767         if (!hctxs)
1768                 goto err_percpu;
1769
1770         map = blk_mq_make_queue_map(set);
1771         if (!map)
1772                 goto err_map;
1773
1774         for (i = 0; i < set->nr_hw_queues; i++) {
1775                 int node = blk_mq_hw_queue_to_node(map, i);
1776
1777                 hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
1778                                         GFP_KERNEL, node);
1779                 if (!hctxs[i])
1780                         goto err_hctxs;
1781
1782                 if (!zalloc_cpumask_var(&hctxs[i]->cpumask, GFP_KERNEL))
1783                         goto err_hctxs;
1784
1785                 atomic_set(&hctxs[i]->nr_active, 0);
1786                 hctxs[i]->numa_node = node;
1787                 hctxs[i]->queue_num = i;
1788         }
1789
1790         q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
1791         if (!q)
1792                 goto err_hctxs;
1793
1794         if (percpu_ref_init(&q->mq_usage_counter, blk_mq_usage_counter_release))
1795                 goto err_map;
1796
1797         setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
1798         blk_queue_rq_timeout(q, 30000);
1799
1800         q->nr_queues = nr_cpu_ids;
1801         q->nr_hw_queues = set->nr_hw_queues;
1802         q->mq_map = map;
1803
1804         q->queue_ctx = ctx;
1805         q->queue_hw_ctx = hctxs;
1806
1807         q->mq_ops = set->ops;
1808         q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
1809
1810         if (!(set->flags & BLK_MQ_F_SG_MERGE))
1811                 q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
1812
1813         q->sg_reserved_size = INT_MAX;
1814
1815         INIT_WORK(&q->requeue_work, blk_mq_requeue_work);
1816         INIT_LIST_HEAD(&q->requeue_list);
1817         spin_lock_init(&q->requeue_lock);
1818
1819         if (q->nr_hw_queues > 1)
1820                 blk_queue_make_request(q, blk_mq_make_request);
1821         else
1822                 blk_queue_make_request(q, blk_sq_make_request);
1823
1824         blk_queue_rq_timed_out(q, blk_mq_rq_timed_out);
1825         if (set->timeout)
1826                 blk_queue_rq_timeout(q, set->timeout);
1827
1828         /*
1829          * Do this after blk_queue_make_request() overrides it...
1830          */
1831         q->nr_requests = set->queue_depth;
1832
1833         if (set->ops->complete)
1834                 blk_queue_softirq_done(q, set->ops->complete);
1835
1836         blk_mq_init_flush(q);
1837         blk_mq_init_cpu_queues(q, set->nr_hw_queues);
1838
1839         q->flush_rq = kzalloc(round_up(sizeof(struct request) +
1840                                 set->cmd_size, cache_line_size()),
1841                                 GFP_KERNEL);
1842         if (!q->flush_rq)
1843                 goto err_hw;
1844
1845         if (blk_mq_init_hw_queues(q, set))
1846                 goto err_flush_rq;
1847
1848         mutex_lock(&all_q_mutex);
1849         list_add_tail(&q->all_q_node, &all_q_list);
1850         mutex_unlock(&all_q_mutex);
1851
1852         blk_mq_add_queue_tag_set(set, q);
1853
1854         blk_mq_map_swqueue(q);
1855
1856         return q;
1857
1858 err_flush_rq:
1859         kfree(q->flush_rq);
1860 err_hw:
1861         blk_cleanup_queue(q);
1862 err_hctxs:
1863         kfree(map);
1864         for (i = 0; i < set->nr_hw_queues; i++) {
1865                 if (!hctxs[i])
1866                         break;
1867                 free_cpumask_var(hctxs[i]->cpumask);
1868                 kfree(hctxs[i]);
1869         }
1870 err_map:
1871         kfree(hctxs);
1872 err_percpu:
1873         free_percpu(ctx);
1874         return ERR_PTR(-ENOMEM);
1875 }
1876 EXPORT_SYMBOL(blk_mq_init_queue);
1877
1878 void blk_mq_free_queue(struct request_queue *q)
1879 {
1880         struct blk_mq_tag_set   *set = q->tag_set;
1881
1882         blk_mq_del_queue_tag_set(q);
1883
1884         blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
1885         blk_mq_free_hw_queues(q, set);
1886
1887         percpu_ref_exit(&q->mq_usage_counter);
1888
1889         free_percpu(q->queue_ctx);
1890         kfree(q->queue_hw_ctx);
1891         kfree(q->mq_map);
1892
1893         q->queue_ctx = NULL;
1894         q->queue_hw_ctx = NULL;
1895         q->mq_map = NULL;
1896
1897         mutex_lock(&all_q_mutex);
1898         list_del_init(&q->all_q_node);
1899         mutex_unlock(&all_q_mutex);
1900 }
1901
1902 /* Basically redo blk_mq_init_queue with queue frozen */
1903 static void blk_mq_queue_reinit(struct request_queue *q)
1904 {
1905         blk_mq_freeze_queue(q);
1906
1907         blk_mq_sysfs_unregister(q);
1908
1909         blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues);
1910
1911         /*
1912          * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
1913          * we should change hctx numa_node according to new topology (this
1914          * involves free and re-allocate memory, worthy doing?)
1915          */
1916
1917         blk_mq_map_swqueue(q);
1918
1919         blk_mq_sysfs_register(q);
1920
1921         blk_mq_unfreeze_queue(q);
1922 }
1923
1924 static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
1925                                       unsigned long action, void *hcpu)
1926 {
1927         struct request_queue *q;
1928
1929         /*
1930          * Before new mappings are established, hotadded cpu might already
1931          * start handling requests. This doesn't break anything as we map
1932          * offline CPUs to first hardware queue. We will re-init the queue
1933          * below to get optimal settings.
1934          */
1935         if (action != CPU_DEAD && action != CPU_DEAD_FROZEN &&
1936             action != CPU_ONLINE && action != CPU_ONLINE_FROZEN)
1937                 return NOTIFY_OK;
1938
1939         mutex_lock(&all_q_mutex);
1940         list_for_each_entry(q, &all_q_list, all_q_node)
1941                 blk_mq_queue_reinit(q);
1942         mutex_unlock(&all_q_mutex);
1943         return NOTIFY_OK;
1944 }
1945
1946 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
1947 {
1948         int i;
1949
1950         for (i = 0; i < set->nr_hw_queues; i++) {
1951                 set->tags[i] = blk_mq_init_rq_map(set, i);
1952                 if (!set->tags[i])
1953                         goto out_unwind;
1954         }
1955
1956         return 0;
1957
1958 out_unwind:
1959         while (--i >= 0)
1960                 blk_mq_free_rq_map(set, set->tags[i], i);
1961
1962         set->tags = NULL;
1963         return -ENOMEM;
1964 }
1965
1966 /*
1967  * Allocate the request maps associated with this tag_set. Note that this
1968  * may reduce the depth asked for, if memory is tight. set->queue_depth
1969  * will be updated to reflect the allocated depth.
1970  */
1971 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
1972 {
1973         unsigned int depth;
1974         int err;
1975
1976         depth = set->queue_depth;
1977         do {
1978                 err = __blk_mq_alloc_rq_maps(set);
1979                 if (!err)
1980                         break;
1981
1982                 set->queue_depth >>= 1;
1983                 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
1984                         err = -ENOMEM;
1985                         break;
1986                 }
1987         } while (set->queue_depth);
1988
1989         if (!set->queue_depth || err) {
1990                 pr_err("blk-mq: failed to allocate request map\n");
1991                 return -ENOMEM;
1992         }
1993
1994         if (depth != set->queue_depth)
1995                 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
1996                                                 depth, set->queue_depth);
1997
1998         return 0;
1999 }
2000
2001 /*
2002  * Alloc a tag set to be associated with one or more request queues.
2003  * May fail with EINVAL for various error conditions. May adjust the
2004  * requested depth down, if if it too large. In that case, the set
2005  * value will be stored in set->queue_depth.
2006  */
2007 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2008 {
2009         if (!set->nr_hw_queues)
2010                 return -EINVAL;
2011         if (!set->queue_depth)
2012                 return -EINVAL;
2013         if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2014                 return -EINVAL;
2015
2016         if (!set->nr_hw_queues || !set->ops->queue_rq || !set->ops->map_queue)
2017                 return -EINVAL;
2018
2019         if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2020                 pr_info("blk-mq: reduced tag depth to %u\n",
2021                         BLK_MQ_MAX_DEPTH);
2022                 set->queue_depth = BLK_MQ_MAX_DEPTH;
2023         }
2024
2025         set->tags = kmalloc_node(set->nr_hw_queues *
2026                                  sizeof(struct blk_mq_tags *),
2027                                  GFP_KERNEL, set->numa_node);
2028         if (!set->tags)
2029                 return -ENOMEM;
2030
2031         if (blk_mq_alloc_rq_maps(set))
2032                 goto enomem;
2033
2034         mutex_init(&set->tag_list_lock);
2035         INIT_LIST_HEAD(&set->tag_list);
2036
2037         return 0;
2038 enomem:
2039         kfree(set->tags);
2040         set->tags = NULL;
2041         return -ENOMEM;
2042 }
2043 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2044
2045 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2046 {
2047         int i;
2048
2049         for (i = 0; i < set->nr_hw_queues; i++) {
2050                 if (set->tags[i])
2051                         blk_mq_free_rq_map(set, set->tags[i], i);
2052         }
2053
2054         kfree(set->tags);
2055         set->tags = NULL;
2056 }
2057 EXPORT_SYMBOL(blk_mq_free_tag_set);
2058
2059 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2060 {
2061         struct blk_mq_tag_set *set = q->tag_set;
2062         struct blk_mq_hw_ctx *hctx;
2063         int i, ret;
2064
2065         if (!set || nr > set->queue_depth)
2066                 return -EINVAL;
2067
2068         ret = 0;
2069         queue_for_each_hw_ctx(q, hctx, i) {
2070                 ret = blk_mq_tag_update_depth(hctx->tags, nr);
2071                 if (ret)
2072                         break;
2073         }
2074
2075         if (!ret)
2076                 q->nr_requests = nr;
2077
2078         return ret;
2079 }
2080
2081 void blk_mq_disable_hotplug(void)
2082 {
2083         mutex_lock(&all_q_mutex);
2084 }
2085
2086 void blk_mq_enable_hotplug(void)
2087 {
2088         mutex_unlock(&all_q_mutex);
2089 }
2090
2091 static int __init blk_mq_init(void)
2092 {
2093         blk_mq_cpu_init();
2094
2095         hotcpu_notifier(blk_mq_queue_reinit_notify, 0);
2096
2097         return 0;
2098 }
2099 subsys_initcall(blk_mq_init);