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/kmemleak.h>
  13 #include <linux/mm.h>
  14 #include <linux/init.h>
  15 #include <linux/slab.h>
  16 #include <linux/workqueue.h>
  17 #include <linux/smp.h>
  18 #include <linux/llist.h>
  19 #include <linux/list_sort.h>
  20 #include <linux/cpu.h>
  21 #include <linux/cache.h>
  22 #include <linux/sched/sysctl.h>
  23 #include <linux/delay.h>
  24 #include <linux/crash_dump.h>
  25 #include <linux/prefetch.h>
  26
  27 #include <trace/events/block.h>
  28
  29 #include <linux/blk-mq.h>
  30 #include "blk.h"
  31 #include "blk-mq.h"
  32 #include "blk-mq-tag.h"
  33 #include "blk-stat.h"
  34 #include "blk-wbt.h"
  35 #include "blk-mq-sched.h"
  36
  37 static DEFINE_MUTEX(all_q_mutex);
  38 static LIST_HEAD(all_q_list);
  39
  40 /*
  41  * Check if any of the ctx's have pending work in this hardware queue
  42  */
  43 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
  44 {
  45         return sbitmap_any_bit_set(&hctx->ctx_map) ||
  46                         !list_empty_careful(&hctx->dispatch) ||
  47                         blk_mq_sched_has_work(hctx);
  48 }
  49
  50 /*
  51  * Mark this ctx as having pending work in this hardware queue
  52  */
  53 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
  54                                      struct blk_mq_ctx *ctx)
  55 {
  56         if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
  57                 sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
  58 }
  59
  60 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
  61                                       struct blk_mq_ctx *ctx)
  62 {
  63         sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
  64 }
  65
  66 void blk_mq_freeze_queue_start(struct request_queue *q)
  67 {
  68         int freeze_depth;
  69
  70         freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
  71         if (freeze_depth == 1) {
  72                 percpu_ref_kill(&q->q_usage_counter);
  73                 blk_mq_run_hw_queues(q, false);
  74         }
  75 }
  76 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
  77
  78 static void blk_mq_freeze_queue_wait(struct request_queue *q)
  79 {
  80         wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
  81 }
  82
  83 /*
  84  * Guarantee no request is in use, so we can change any data structure of
  85  * the queue afterward.
  86  */
  87 void blk_freeze_queue(struct request_queue *q)
  88 {
  89         /*
  90          * In the !blk_mq case we are only calling this to kill the
  91          * q_usage_counter, otherwise this increases the freeze depth
  92          * and waits for it to return to zero.  For this reason there is
  93          * no blk_unfreeze_queue(), and blk_freeze_queue() is not
  94          * exported to drivers as the only user for unfreeze is blk_mq.
  95          */
  96         blk_mq_freeze_queue_start(q);
  97         blk_mq_freeze_queue_wait(q);
  98 }
  99
 100 void blk_mq_freeze_queue(struct request_queue *q)
 101 {
 102         /*
 103          * ...just an alias to keep freeze and unfreeze actions balanced
 104          * in the blk_mq_* namespace
 105          */
 106         blk_freeze_queue(q);
 107 }
 108 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
 109
 110 void blk_mq_unfreeze_queue(struct request_queue *q)
 111 {
 112         int freeze_depth;
 113
 114         freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
 115         WARN_ON_ONCE(freeze_depth < 0);
 116         if (!freeze_depth) {
 117                 percpu_ref_reinit(&q->q_usage_counter);
 118                 wake_up_all(&q->mq_freeze_wq);
 119         }
 120 }
 121 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
 122
 123 /**
 124  * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished
 125  * @q: request queue.
 126  *
 127  * Note: this function does not prevent that the struct request end_io()
 128  * callback function is invoked. Additionally, it is not prevented that
 129  * new queue_rq() calls occur unless the queue has been stopped first.
 130  */
 131 void blk_mq_quiesce_queue(struct request_queue *q)
 132 {
 133         struct blk_mq_hw_ctx *hctx;
 134         unsigned int i;
 135         bool rcu = false;
 136
 137         blk_mq_stop_hw_queues(q);
 138
 139         queue_for_each_hw_ctx(q, hctx, i) {
 140                 if (hctx->flags & BLK_MQ_F_BLOCKING)
 141                         synchronize_srcu(&hctx->queue_rq_srcu);
 142                 else
 143                         rcu = true;
 144         }
 145         if (rcu)
 146                 synchronize_rcu();
 147 }
 148 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
 149
 150 void blk_mq_wake_waiters(struct request_queue *q)
 151 {
 152         struct blk_mq_hw_ctx *hctx;
 153         unsigned int i;
 154
 155         queue_for_each_hw_ctx(q, hctx, i)
 156                 if (blk_mq_hw_queue_mapped(hctx))
 157                         blk_mq_tag_wakeup_all(hctx->tags, true);
 158
 159         /*
 160          * If we are called because the queue has now been marked as
 161          * dying, we need to ensure that processes currently waiting on
 162          * the queue are notified as well.
 163          */
 164         wake_up_all(&q->mq_freeze_wq);
 165 }
 166
 167 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
 168 {
 169         return blk_mq_has_free_tags(hctx->tags);
 170 }
 171 EXPORT_SYMBOL(blk_mq_can_queue);
 172
 173 void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
 174                         struct request *rq, unsigned int op)
 175 {
 176         INIT_LIST_HEAD(&rq->queuelist);
 177         /* csd/requeue_work/fifo_time is initialized before use */
 178         rq->q = q;
 179         rq->mq_ctx = ctx;
 180         rq->cmd_flags = op;
 181         if (blk_queue_io_stat(q))
 182                 rq->rq_flags |= RQF_IO_STAT;
 183         /* do not touch atomic flags, it needs atomic ops against the timer */
 184         rq->cpu = -1;
 185         INIT_HLIST_NODE(&rq->hash);
 186         RB_CLEAR_NODE(&rq->rb_node);
 187         rq->rq_disk = NULL;
 188         rq->part = NULL;
 189         rq->start_time = jiffies;
 190 #ifdef CONFIG_BLK_CGROUP
 191         rq->rl = NULL;
 192         set_start_time_ns(rq);
 193         rq->io_start_time_ns = 0;
 194 #endif
 195         rq->nr_phys_segments = 0;
 196 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 197         rq->nr_integrity_segments = 0;
 198 #endif
 199         rq->special = NULL;
 200         /* tag was already set */
 201         rq->errors = 0;
 202         rq->extra_len = 0;
 203
 204         INIT_LIST_HEAD(&rq->timeout_list);
 205         rq->timeout = 0;
 206
 207         rq->end_io = NULL;
 208         rq->end_io_data = NULL;
 209         rq->next_rq = NULL;
 210
 211         ctx->rq_dispatched[op_is_sync(op)]++;
 212 }
 213 EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init);
 214
 215 struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
 216                                        unsigned int op)
 217 {
 218         struct request *rq;
 219         unsigned int tag;
 220
 221         tag = blk_mq_get_tag(data);
 222         if (tag != BLK_MQ_TAG_FAIL) {
 223                 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
 224
 225                 rq = tags->static_rqs[tag];
 226
 227                 if (data->flags & BLK_MQ_REQ_INTERNAL) {
 228                         rq->tag = -1;
 229                         rq->internal_tag = tag;
 230                 } else {
 231                         if (blk_mq_tag_busy(data->hctx)) {
 232                                 rq->rq_flags = RQF_MQ_INFLIGHT;
 233                                 atomic_inc(&data->hctx->nr_active);
 234                         }
 235                         rq->tag = tag;
 236                         rq->internal_tag = -1;
 237                 }
 238
 239                 blk_mq_rq_ctx_init(data->q, data->ctx, rq, op);
 240                 return rq;
 241         }
 242
 243         return NULL;
 244 }
 245 EXPORT_SYMBOL_GPL(__blk_mq_alloc_request);
 246
 247 struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
 248                 unsigned int flags)
 249 {
 250         struct blk_mq_alloc_data alloc_data = { .flags = flags };
 251         struct request *rq;
 252         int ret;
 253
 254         ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
 255         if (ret)
 256                 return ERR_PTR(ret);
 257
 258         rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
 259
 260         blk_mq_put_ctx(alloc_data.ctx);
 261         blk_queue_exit(q);
 262
 263         if (!rq)
 264                 return ERR_PTR(-EWOULDBLOCK);
 265
 266         rq->__data_len = 0;
 267         rq->__sector = (sector_t) -1;
 268         rq->bio = rq->biotail = NULL;
 269         return rq;
 270 }
 271 EXPORT_SYMBOL(blk_mq_alloc_request);
 272
 273 struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
 274                 unsigned int flags, unsigned int hctx_idx)
 275 {
 276         struct blk_mq_hw_ctx *hctx;
 277         struct blk_mq_ctx *ctx;
 278         struct request *rq;
 279         struct blk_mq_alloc_data alloc_data;
 280         int ret;
 281
 282         /*
 283          * If the tag allocator sleeps we could get an allocation for a
 284          * different hardware context.  No need to complicate the low level
 285          * allocator for this for the rare use case of a command tied to
 286          * a specific queue.
 287          */
 288         if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
 289                 return ERR_PTR(-EINVAL);
 290
 291         if (hctx_idx >= q->nr_hw_queues)
 292                 return ERR_PTR(-EIO);
 293
 294         ret = blk_queue_enter(q, true);
 295         if (ret)
 296                 return ERR_PTR(ret);
 297
 298         /*
 299          * Check if the hardware context is actually mapped to anything.
 300          * If not tell the caller that it should skip this queue.
 301          */
 302         hctx = q->queue_hw_ctx[hctx_idx];
 303         if (!blk_mq_hw_queue_mapped(hctx)) {
 304                 ret = -EXDEV;
 305                 goto out_queue_exit;
 306         }
 307         ctx = __blk_mq_get_ctx(q, cpumask_first(hctx->cpumask));
 308
 309         blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
 310         rq = __blk_mq_alloc_request(&alloc_data, rw);
 311         if (!rq) {
 312                 ret = -EWOULDBLOCK;
 313                 goto out_queue_exit;
 314         }
 315
 316         return rq;
 317
 318 out_queue_exit:
 319         blk_queue_exit(q);
 320         return ERR_PTR(ret);
 321 }
 322 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
 323
 324 void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
 325                              struct request *rq)
 326 {
 327         const int sched_tag = rq->internal_tag;
 328         struct request_queue *q = rq->q;
 329
 330         if (rq->rq_flags & RQF_MQ_INFLIGHT)
 331                 atomic_dec(&hctx->nr_active);
 332
 333         wbt_done(q->rq_wb, &rq->issue_stat);
 334         rq->rq_flags = 0;
 335
 336         clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 337         clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
 338         if (rq->tag != -1)
 339                 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
 340         if (sched_tag != -1)
 341                 blk_mq_sched_completed_request(hctx, rq);
 342         blk_mq_sched_restart_queues(hctx);
 343         blk_queue_exit(q);
 344 }
 345
 346 static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx *hctx,
 347                                      struct request *rq)
 348 {
 349         struct blk_mq_ctx *ctx = rq->mq_ctx;
 350
 351         ctx->rq_completed[rq_is_sync(rq)]++;
 352         __blk_mq_finish_request(hctx, ctx, rq);
 353 }
 354
 355 void blk_mq_finish_request(struct request *rq)
 356 {
 357         blk_mq_finish_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
 358 }
 359
 360 void blk_mq_free_request(struct request *rq)
 361 {
 362         blk_mq_sched_put_request(rq);
 363 }
 364 EXPORT_SYMBOL_GPL(blk_mq_free_request);
 365
 366 inline void __blk_mq_end_request(struct request *rq, int error)
 367 {
 368         blk_account_io_done(rq);
 369
 370         if (rq->end_io) {
 371                 wbt_done(rq->q->rq_wb, &rq->issue_stat);
 372                 rq->end_io(rq, error);
 373         } else {
 374                 if (unlikely(blk_bidi_rq(rq)))
 375                         blk_mq_free_request(rq->next_rq);
 376                 blk_mq_free_request(rq);
 377         }
 378 }
 379 EXPORT_SYMBOL(__blk_mq_end_request);
 380
 381 void blk_mq_end_request(struct request *rq, int error)
 382 {
 383         if (blk_update_request(rq, error, blk_rq_bytes(rq)))
 384                 BUG();
 385         __blk_mq_end_request(rq, error);
 386 }
 387 EXPORT_SYMBOL(blk_mq_end_request);
 388
 389 static void __blk_mq_complete_request_remote(void *data)
 390 {
 391         struct request *rq = data;
 392
 393         rq->q->softirq_done_fn(rq);
 394 }
 395
 396 static void blk_mq_ipi_complete_request(struct request *rq)
 397 {
 398         struct blk_mq_ctx *ctx = rq->mq_ctx;
 399         bool shared = false;
 400         int cpu;
 401
 402         if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
 403                 rq->q->softirq_done_fn(rq);
 404                 return;
 405         }
 406
 407         cpu = get_cpu();
 408         if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
 409                 shared = cpus_share_cache(cpu, ctx->cpu);
 410
 411         if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
 412                 rq->csd.func = __blk_mq_complete_request_remote;
 413                 rq->csd.info = rq;
 414                 rq->csd.flags = 0;
 415                 smp_call_function_single_async(ctx->cpu, &rq->csd);
 416         } else {
 417                 rq->q->softirq_done_fn(rq);
 418         }
 419         put_cpu();
 420 }
 421
 422 static void blk_mq_stat_add(struct request *rq)
 423 {
 424         if (rq->rq_flags & RQF_STATS) {
 425                 /*
 426                  * We could rq->mq_ctx here, but there's less of a risk
 427                  * of races if we have the completion event add the stats
 428                  * to the local software queue.
 429                  */
 430                 struct blk_mq_ctx *ctx;
 431
 432                 ctx = __blk_mq_get_ctx(rq->q, raw_smp_processor_id());
 433                 blk_stat_add(&ctx->stat[rq_data_dir(rq)], rq);
 434         }
 435 }
 436
 437 static void __blk_mq_complete_request(struct request *rq)
 438 {
 439         struct request_queue *q = rq->q;
 440
 441         blk_mq_stat_add(rq);
 442
 443         if (!q->softirq_done_fn)
 444                 blk_mq_end_request(rq, rq->errors);
 445         else
 446                 blk_mq_ipi_complete_request(rq);
 447 }
 448
 449 /**
 450  * blk_mq_complete_request - end I/O on a request
 451  * @rq:         the request being processed
 452  *
 453  * Description:
 454  *      Ends all I/O on a request. It does not handle partial completions.
 455  *      The actual completion happens out-of-order, through a IPI handler.
 456  **/
 457 void blk_mq_complete_request(struct request *rq, int error)
 458 {
 459         struct request_queue *q = rq->q;
 460
 461         if (unlikely(blk_should_fake_timeout(q)))
 462                 return;
 463         if (!blk_mark_rq_complete(rq)) {
 464                 rq->errors = error;
 465                 __blk_mq_complete_request(rq);
 466         }
 467 }
 468 EXPORT_SYMBOL(blk_mq_complete_request);
 469
 470 int blk_mq_request_started(struct request *rq)
 471 {
 472         return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 473 }
 474 EXPORT_SYMBOL_GPL(blk_mq_request_started);
 475
 476 void blk_mq_start_request(struct request *rq)
 477 {
 478         struct request_queue *q = rq->q;
 479
 480         blk_mq_sched_started_request(rq);
 481
 482         trace_block_rq_issue(q, rq);
 483
 484         if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
 485                 blk_stat_set_issue_time(&rq->issue_stat);
 486                 rq->rq_flags |= RQF_STATS;
 487                 wbt_issue(q->rq_wb, &rq->issue_stat);
 488         }
 489
 490         blk_add_timer(rq);
 491
 492         /*
 493          * Ensure that ->deadline is visible before set the started
 494          * flag and clear the completed flag.
 495          */
 496         smp_mb__before_atomic();
 497
 498         /*
 499          * Mark us as started and clear complete. Complete might have been
 500          * set if requeue raced with timeout, which then marked it as
 501          * complete. So be sure to clear complete again when we start
 502          * the request, otherwise we'll ignore the completion event.
 503          */
 504         if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
 505                 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 506         if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
 507                 clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
 508
 509         if (q->dma_drain_size && blk_rq_bytes(rq)) {
 510                 /*
 511                  * Make sure space for the drain appears.  We know we can do
 512                  * this because max_hw_segments has been adjusted to be one
 513                  * fewer than the device can handle.
 514                  */
 515                 rq->nr_phys_segments++;
 516         }
 517 }
 518 EXPORT_SYMBOL(blk_mq_start_request);
 519
 520 static void __blk_mq_requeue_request(struct request *rq)
 521 {
 522         struct request_queue *q = rq->q;
 523
 524         trace_block_rq_requeue(q, rq);
 525         wbt_requeue(q->rq_wb, &rq->issue_stat);
 526         blk_mq_sched_requeue_request(rq);
 527
 528         if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
 529                 if (q->dma_drain_size && blk_rq_bytes(rq))
 530                         rq->nr_phys_segments--;
 531         }
 532 }
 533
 534 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
 535 {
 536         __blk_mq_requeue_request(rq);
 537
 538         BUG_ON(blk_queued_rq(rq));
 539         blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
 540 }
 541 EXPORT_SYMBOL(blk_mq_requeue_request);
 542
 543 static void blk_mq_requeue_work(struct work_struct *work)
 544 {
 545         struct request_queue *q =
 546                 container_of(work, struct request_queue, requeue_work.work);
 547         LIST_HEAD(rq_list);
 548         struct request *rq, *next;
 549         unsigned long flags;
 550
 551         spin_lock_irqsave(&q->requeue_lock, flags);
 552         list_splice_init(&q->requeue_list, &rq_list);
 553         spin_unlock_irqrestore(&q->requeue_lock, flags);
 554
 555         list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
 556                 if (!(rq->rq_flags & RQF_SOFTBARRIER))
 557                         continue;
 558
 559                 rq->rq_flags &= ~RQF_SOFTBARRIER;
 560                 list_del_init(&rq->queuelist);
 561                 blk_mq_sched_insert_request(rq, true, false, false, true);
 562         }
 563
 564         while (!list_empty(&rq_list)) {
 565                 rq = list_entry(rq_list.next, struct request, queuelist);
 566                 list_del_init(&rq->queuelist);
 567                 blk_mq_sched_insert_request(rq, false, false, false, true);
 568         }
 569
 570         blk_mq_run_hw_queues(q, false);
 571 }
 572
 573 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
 574                                 bool kick_requeue_list)
 575 {
 576         struct request_queue *q = rq->q;
 577         unsigned long flags;
 578
 579         /*
 580          * We abuse this flag that is otherwise used by the I/O scheduler to
 581          * request head insertation from the workqueue.
 582          */
 583         BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
 584
 585         spin_lock_irqsave(&q->requeue_lock, flags);
 586         if (at_head) {
 587                 rq->rq_flags |= RQF_SOFTBARRIER;
 588                 list_add(&rq->queuelist, &q->requeue_list);
 589         } else {
 590                 list_add_tail(&rq->queuelist, &q->requeue_list);
 591         }
 592         spin_unlock_irqrestore(&q->requeue_lock, flags);
 593
 594         if (kick_requeue_list)
 595                 blk_mq_kick_requeue_list(q);
 596 }
 597 EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
 598
 599 void blk_mq_kick_requeue_list(struct request_queue *q)
 600 {
 601         kblockd_schedule_delayed_work(&q->requeue_work, 0);
 602 }
 603 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
 604
 605 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
 606                                     unsigned long msecs)
 607 {
 608         kblockd_schedule_delayed_work(&q->requeue_work,
 609                                       msecs_to_jiffies(msecs));
 610 }
 611 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
 612
 613 void blk_mq_abort_requeue_list(struct request_queue *q)
 614 {
 615         unsigned long flags;
 616         LIST_HEAD(rq_list);
 617
 618         spin_lock_irqsave(&q->requeue_lock, flags);
 619         list_splice_init(&q->requeue_list, &rq_list);
 620         spin_unlock_irqrestore(&q->requeue_lock, flags);
 621
 622         while (!list_empty(&rq_list)) {
 623                 struct request *rq;
 624
 625                 rq = list_first_entry(&rq_list, struct request, queuelist);
 626                 list_del_init(&rq->queuelist);
 627                 rq->errors = -EIO;
 628                 blk_mq_end_request(rq, rq->errors);
 629         }
 630 }
 631 EXPORT_SYMBOL(blk_mq_abort_requeue_list);
 632
 633 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
 634 {
 635         if (tag < tags->nr_tags) {
 636                 prefetch(tags->rqs[tag]);
 637                 return tags->rqs[tag];
 638         }
 639
 640         return NULL;
 641 }
 642 EXPORT_SYMBOL(blk_mq_tag_to_rq);
 643
 644 struct blk_mq_timeout_data {
 645         unsigned long next;
 646         unsigned int next_set;
 647 };
 648
 649 void blk_mq_rq_timed_out(struct request *req, bool reserved)
 650 {
 651         const struct blk_mq_ops *ops = req->q->mq_ops;
 652         enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
 653
 654         /*
 655          * We know that complete is set at this point. If STARTED isn't set
 656          * anymore, then the request isn't active and the "timeout" should
 657          * just be ignored. This can happen due to the bitflag ordering.
 658          * Timeout first checks if STARTED is set, and if it is, assumes
 659          * the request is active. But if we race with completion, then
 660          * we both flags will get cleared. So check here again, and ignore
 661          * a timeout event with a request that isn't active.
 662          */
 663         if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
 664                 return;
 665
 666         if (ops->timeout)
 667                 ret = ops->timeout(req, reserved);
 668
 669         switch (ret) {
 670         case BLK_EH_HANDLED:
 671                 __blk_mq_complete_request(req);
 672                 break;
 673         case BLK_EH_RESET_TIMER:
 674                 blk_add_timer(req);
 675                 blk_clear_rq_complete(req);
 676                 break;
 677         case BLK_EH_NOT_HANDLED:
 678                 break;
 679         default:
 680                 printk(KERN_ERR "block: bad eh return: %d\n", ret);
 681                 break;
 682         }
 683 }
 684
 685 static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
 686                 struct request *rq, void *priv, bool reserved)
 687 {
 688         struct blk_mq_timeout_data *data = priv;
 689
 690         if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
 691                 /*
 692                  * If a request wasn't started before the queue was
 693                  * marked dying, kill it here or it'll go unnoticed.
 694                  */
 695                 if (unlikely(blk_queue_dying(rq->q))) {
 696                         rq->errors = -EIO;
 697                         blk_mq_end_request(rq, rq->errors);
 698                 }
 699                 return;
 700         }
 701
 702         if (time_after_eq(jiffies, rq->deadline)) {
 703                 if (!blk_mark_rq_complete(rq))
 704                         blk_mq_rq_timed_out(rq, reserved);
 705         } else if (!data->next_set || time_after(data->next, rq->deadline)) {
 706                 data->next = rq->deadline;
 707                 data->next_set = 1;
 708         }
 709 }
 710
 711 static void blk_mq_timeout_work(struct work_struct *work)
 712 {
 713         struct request_queue *q =
 714                 container_of(work, struct request_queue, timeout_work);
 715         struct blk_mq_timeout_data data = {
 716                 .next           = 0,
 717                 .next_set       = 0,
 718         };
 719         int i;
 720
 721         /* A deadlock might occur if a request is stuck requiring a
 722          * timeout at the same time a queue freeze is waiting
 723          * completion, since the timeout code would not be able to
 724          * acquire the queue reference here.
 725          *
 726          * That's why we don't use blk_queue_enter here; instead, we use
 727          * percpu_ref_tryget directly, because we need to be able to
 728          * obtain a reference even in the short window between the queue
 729          * starting to freeze, by dropping the first reference in
 730          * blk_mq_freeze_queue_start, and the moment the last request is
 731          * consumed, marked by the instant q_usage_counter reaches
 732          * zero.
 733          */
 734         if (!percpu_ref_tryget(&q->q_usage_counter))
 735                 return;
 736
 737         blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
 738
 739         if (data.next_set) {
 740                 data.next = blk_rq_timeout(round_jiffies_up(data.next));
 741                 mod_timer(&q->timeout, data.next);
 742         } else {
 743                 struct blk_mq_hw_ctx *hctx;
 744
 745                 queue_for_each_hw_ctx(q, hctx, i) {
 746                         /* the hctx may be unmapped, so check it here */
 747                         if (blk_mq_hw_queue_mapped(hctx))
 748                                 blk_mq_tag_idle(hctx);
 749                 }
 750         }
 751         blk_queue_exit(q);
 752 }
 753
 754 /*
 755  * Reverse check our software queue for entries that we could potentially
 756  * merge with. Currently includes a hand-wavy stop count of 8, to not spend
 757  * too much time checking for merges.
 758  */
 759 static bool blk_mq_attempt_merge(struct request_queue *q,
 760                                  struct blk_mq_ctx *ctx, struct bio *bio)
 761 {
 762         struct request *rq;
 763         int checked = 8;
 764
 765         list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
 766                 bool merged = false;
 767
 768                 if (!checked--)
 769                         break;
 770
 771                 if (!blk_rq_merge_ok(rq, bio))
 772                         continue;
 773
 774                 switch (blk_try_merge(rq, bio)) {
 775                 case ELEVATOR_BACK_MERGE:
 776                         if (blk_mq_sched_allow_merge(q, rq, bio))
 777                                 merged = bio_attempt_back_merge(q, rq, bio);
 778                         break;
 779                 case ELEVATOR_FRONT_MERGE:
 780                         if (blk_mq_sched_allow_merge(q, rq, bio))
 781                                 merged = bio_attempt_front_merge(q, rq, bio);
 782                         break;
 783                 case ELEVATOR_DISCARD_MERGE:
 784                         merged = bio_attempt_discard_merge(q, rq, bio);
 785                         break;
 786                 default:
 787                         continue;
 788                 }
 789
 790                 if (merged)
 791                         ctx->rq_merged++;
 792                 return merged;
 793         }
 794
 795         return false;
 796 }
 797
 798 struct flush_busy_ctx_data {
 799         struct blk_mq_hw_ctx *hctx;
 800         struct list_head *list;
 801 };
 802
 803 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
 804 {
 805         struct flush_busy_ctx_data *flush_data = data;
 806         struct blk_mq_hw_ctx *hctx = flush_data->hctx;
 807         struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
 808
 809         sbitmap_clear_bit(sb, bitnr);
 810         spin_lock(&ctx->lock);
 811         list_splice_tail_init(&ctx->rq_list, flush_data->list);
 812         spin_unlock(&ctx->lock);
 813         return true;
 814 }
 815
 816 /*
 817  * Process software queues that have been marked busy, splicing them
 818  * to the for-dispatch
 819  */
 820 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
 821 {
 822         struct flush_busy_ctx_data data = {
 823                 .hctx = hctx,
 824                 .list = list,
 825         };
 826
 827         sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
 828 }
 829 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
 830
 831 static inline unsigned int queued_to_index(unsigned int queued)
 832 {
 833         if (!queued)
 834                 return 0;
 835
 836         return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
 837 }
 838
 839 bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
 840                            bool wait)
 841 {
 842         struct blk_mq_alloc_data data = {
 843                 .q = rq->q,
 844                 .hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
 845                 .flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
 846         };
 847
 848         if (rq->tag != -1) {
 849 done:
 850                 if (hctx)
 851                         *hctx = data.hctx;
 852                 return true;
 853         }
 854
 855         if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
 856                 data.flags |= BLK_MQ_REQ_RESERVED;
 857
 858         rq->tag = blk_mq_get_tag(&data);
 859         if (rq->tag >= 0) {
 860                 if (blk_mq_tag_busy(data.hctx)) {
 861                         rq->rq_flags |= RQF_MQ_INFLIGHT;
 862                         atomic_inc(&data.hctx->nr_active);
 863                 }
 864                 data.hctx->tags->rqs[rq->tag] = rq;
 865                 goto done;
 866         }
 867
 868         return false;
 869 }
 870
 871 static void blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
 872                                   struct request *rq)
 873 {
 874         if (rq->tag == -1 || rq->internal_tag == -1)
 875                 return;
 876
 877         blk_mq_put_tag(hctx, hctx->tags, rq->mq_ctx, rq->tag);
 878         rq->tag = -1;
 879
 880         if (rq->rq_flags & RQF_MQ_INFLIGHT) {
 881                 rq->rq_flags &= ~RQF_MQ_INFLIGHT;
 882                 atomic_dec(&hctx->nr_active);
 883         }
 884 }
 885
 886 /*
 887  * If we fail getting a driver tag because all the driver tags are already
 888  * assigned and on the dispatch list, BUT the first entry does not have a
 889  * tag, then we could deadlock. For that case, move entries with assigned
 890  * driver tags to the front, leaving the set of tagged requests in the
 891  * same order, and the untagged set in the same order.
 892  */
 893 static bool reorder_tags_to_front(struct list_head *list)
 894 {
 895         struct request *rq, *tmp, *first = NULL;
 896
 897         list_for_each_entry_safe_reverse(rq, tmp, list, queuelist) {
 898                 if (rq == first)
 899                         break;
 900                 if (rq->tag != -1) {
 901                         list_move(&rq->queuelist, list);
 902                         if (!first)
 903                                 first = rq;
 904                 }
 905         }
 906
 907         return first != NULL;
 908 }
 909
 910 static int blk_mq_dispatch_wake(wait_queue_t *wait, unsigned mode, int flags,
 911                                 void *key)
 912 {
 913         struct blk_mq_hw_ctx *hctx;
 914
 915         hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
 916
 917         list_del(&wait->task_list);
 918         clear_bit_unlock(BLK_MQ_S_TAG_WAITING, &hctx->state);
 919         blk_mq_run_hw_queue(hctx, true);
 920         return 1;
 921 }
 922
 923 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx *hctx)
 924 {
 925         struct sbq_wait_state *ws;
 926
 927         /*
 928          * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
 929          * The thread which wins the race to grab this bit adds the hardware
 930          * queue to the wait queue.
 931          */
 932         if (test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state) ||
 933             test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING, &hctx->state))
 934                 return false;
 935
 936         init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
 937         ws = bt_wait_ptr(&hctx->tags->bitmap_tags, hctx);
 938
 939         /*
 940          * As soon as this returns, it's no longer safe to fiddle with
 941          * hctx->dispatch_wait, since a completion can wake up the wait queue
 942          * and unlock the bit.
 943          */
 944         add_wait_queue(&ws->wait, &hctx->dispatch_wait);
 945         return true;
 946 }
 947
 948 bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
 949 {
 950         struct request_queue *q = hctx->queue;
 951         struct request *rq;
 952         LIST_HEAD(driver_list);
 953         struct list_head *dptr;
 954         int queued, ret = BLK_MQ_RQ_QUEUE_OK;
 955
 956         /*
 957          * Start off with dptr being NULL, so we start the first request
 958          * immediately, even if we have more pending.
 959          */
 960         dptr = NULL;
 961
 962         /*
 963          * Now process all the entries, sending them to the driver.
 964          */
 965         queued = 0;
 966         while (!list_empty(list)) {
 967                 struct blk_mq_queue_data bd;
 968
 969                 rq = list_first_entry(list, struct request, queuelist);
 970                 if (!blk_mq_get_driver_tag(rq, &hctx, false)) {
 971                         if (!queued && reorder_tags_to_front(list))
 972                                 continue;
 973
 974                         /*
 975                          * The initial allocation attempt failed, so we need to
 976                          * rerun the hardware queue when a tag is freed.
 977                          */
 978                         if (blk_mq_dispatch_wait_add(hctx)) {
 979                                 /*
 980                                  * It's possible that a tag was freed in the
 981                                  * window between the allocation failure and
 982                                  * adding the hardware queue to the wait queue.
 983                                  */
 984                                 if (!blk_mq_get_driver_tag(rq, &hctx, false))
 985                                         break;
 986                         } else {
 987                                 break;
 988                         }
 989                 }
 990
 991                 list_del_init(&rq->queuelist);
 992
 993                 bd.rq = rq;
 994                 bd.list = dptr;
 995                 bd.last = list_empty(list);
 996
 997                 ret = q->mq_ops->queue_rq(hctx, &bd);
 998                 switch (ret) {
 999                 case BLK_MQ_RQ_QUEUE_OK:
1000                         queued++;
1001                         break;
1002                 case BLK_MQ_RQ_QUEUE_BUSY:
1003                         blk_mq_put_driver_tag(hctx, rq);
1004                         list_add(&rq->queuelist, list);
1005                         __blk_mq_requeue_request(rq);
1006                         break;
1007                 default:
1008                         pr_err("blk-mq: bad return on queue: %d\n", ret);
1009                 case BLK_MQ_RQ_QUEUE_ERROR:
1010                         rq->errors = -EIO;
1011                         blk_mq_end_request(rq, rq->errors);
1012                         break;
1013                 }
1014
1015                 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
1016                         break;
1017
1018                 /*
1019                  * We've done the first request. If we have more than 1
1020                  * left in the list, set dptr to defer issue.
1021                  */
1022                 if (!dptr && list->next != list->prev)
1023                         dptr = &driver_list;
1024         }
1025
1026         hctx->dispatched[queued_to_index(queued)]++;
1027
1028         /*
1029          * Any items that need requeuing? Stuff them into hctx->dispatch,
1030          * that is where we will continue on next queue run.
1031          */
1032         if (!list_empty(list)) {
1033                 spin_lock(&hctx->lock);
1034                 list_splice_init(list, &hctx->dispatch);
1035                 spin_unlock(&hctx->lock);
1036
1037                 /*
1038                  * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
1039                  * it's possible the queue is stopped and restarted again
1040                  * before this. Queue restart will dispatch requests. And since
1041                  * requests in rq_list aren't added into hctx->dispatch yet,
1042                  * the requests in rq_list might get lost.
1043                  *
1044                  * blk_mq_run_hw_queue() already checks the STOPPED bit
1045                  *
1046                  * If RESTART or TAG_WAITING is set, then let completion restart
1047                  * the queue instead of potentially looping here.
1048                  */
1049                 if (!blk_mq_sched_needs_restart(hctx) &&
1050                     !test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state))
1051                         blk_mq_run_hw_queue(hctx, true);
1052         }
1053
1054         return queued != 0;
1055 }
1056
1057 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1058 {
1059         int srcu_idx;
1060
1061         WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1062                 cpu_online(hctx->next_cpu));
1063
1064         if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
1065                 rcu_read_lock();
1066                 blk_mq_sched_dispatch_requests(hctx);
1067                 rcu_read_unlock();
1068         } else {
1069                 srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
1070                 blk_mq_sched_dispatch_requests(hctx);
1071                 srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
1072         }
1073 }
1074
1075 /*
1076  * It'd be great if the workqueue API had a way to pass
1077  * in a mask and had some smarts for more clever placement.
1078  * For now we just round-robin here, switching for every
1079  * BLK_MQ_CPU_WORK_BATCH queued items.
1080  */
1081 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1082 {
1083         if (hctx->queue->nr_hw_queues == 1)
1084                 return WORK_CPU_UNBOUND;
1085
1086         if (--hctx->next_cpu_batch <= 0) {
1087                 int next_cpu;
1088
1089                 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
1090                 if (next_cpu >= nr_cpu_ids)
1091                         next_cpu = cpumask_first(hctx->cpumask);
1092
1093                 hctx->next_cpu = next_cpu;
1094                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1095         }
1096
1097         return hctx->next_cpu;
1098 }
1099
1100 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1101 {
1102         if (unlikely(blk_mq_hctx_stopped(hctx) ||
1103                      !blk_mq_hw_queue_mapped(hctx)))
1104                 return;
1105
1106         if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1107                 int cpu = get_cpu();
1108                 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1109                         __blk_mq_run_hw_queue(hctx);
1110                         put_cpu();
1111                         return;
1112                 }
1113
1114                 put_cpu();
1115         }
1116
1117         kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work);
1118 }
1119
1120 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1121 {
1122         struct blk_mq_hw_ctx *hctx;
1123         int i;
1124
1125         queue_for_each_hw_ctx(q, hctx, i) {
1126                 if (!blk_mq_hctx_has_pending(hctx) ||
1127                     blk_mq_hctx_stopped(hctx))
1128                         continue;
1129
1130                 blk_mq_run_hw_queue(hctx, async);
1131         }
1132 }
1133 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1134
1135 /**
1136  * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1137  * @q: request queue.
1138  *
1139  * The caller is responsible for serializing this function against
1140  * blk_mq_{start,stop}_hw_queue().
1141  */
1142 bool blk_mq_queue_stopped(struct request_queue *q)
1143 {
1144         struct blk_mq_hw_ctx *hctx;
1145         int i;
1146
1147         queue_for_each_hw_ctx(q, hctx, i)
1148                 if (blk_mq_hctx_stopped(hctx))
1149                         return true;
1150
1151         return false;
1152 }
1153 EXPORT_SYMBOL(blk_mq_queue_stopped);
1154
1155 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1156 {
1157         cancel_work(&hctx->run_work);
1158         cancel_delayed_work(&hctx->delay_work);
1159         set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1160 }
1161 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1162
1163 void blk_mq_stop_hw_queues(struct request_queue *q)
1164 {
1165         struct blk_mq_hw_ctx *hctx;
1166         int i;
1167
1168         queue_for_each_hw_ctx(q, hctx, i)
1169                 blk_mq_stop_hw_queue(hctx);
1170 }
1171 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1172
1173 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1174 {
1175         clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1176
1177         blk_mq_run_hw_queue(hctx, false);
1178 }
1179 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1180
1181 void blk_mq_start_hw_queues(struct request_queue *q)
1182 {
1183         struct blk_mq_hw_ctx *hctx;
1184         int i;
1185
1186         queue_for_each_hw_ctx(q, hctx, i)
1187                 blk_mq_start_hw_queue(hctx);
1188 }
1189 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1190
1191 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1192 {
1193         if (!blk_mq_hctx_stopped(hctx))
1194                 return;
1195
1196         clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1197         blk_mq_run_hw_queue(hctx, async);
1198 }
1199 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1200
1201 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1202 {
1203         struct blk_mq_hw_ctx *hctx;
1204         int i;
1205
1206         queue_for_each_hw_ctx(q, hctx, i)
1207                 blk_mq_start_stopped_hw_queue(hctx, async);
1208 }
1209 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1210
1211 static void blk_mq_run_work_fn(struct work_struct *work)
1212 {
1213         struct blk_mq_hw_ctx *hctx;
1214
1215         hctx = container_of(work, struct blk_mq_hw_ctx, run_work);
1216
1217         __blk_mq_run_hw_queue(hctx);
1218 }
1219
1220 static void blk_mq_delay_work_fn(struct work_struct *work)
1221 {
1222         struct blk_mq_hw_ctx *hctx;
1223
1224         hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
1225
1226         if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
1227                 __blk_mq_run_hw_queue(hctx);
1228 }
1229
1230 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1231 {
1232         if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
1233                 return;
1234
1235         blk_mq_stop_hw_queue(hctx);
1236         kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1237                         &hctx->delay_work, msecs_to_jiffies(msecs));
1238 }
1239 EXPORT_SYMBOL(blk_mq_delay_queue);
1240
1241 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1242                                             struct request *rq,
1243                                             bool at_head)
1244 {
1245         struct blk_mq_ctx *ctx = rq->mq_ctx;
1246
1247         trace_block_rq_insert(hctx->queue, rq);
1248
1249         if (at_head)
1250                 list_add(&rq->queuelist, &ctx->rq_list);
1251         else
1252                 list_add_tail(&rq->queuelist, &ctx->rq_list);
1253 }
1254
1255 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1256                              bool at_head)
1257 {
1258         struct blk_mq_ctx *ctx = rq->mq_ctx;
1259
1260         __blk_mq_insert_req_list(hctx, rq, at_head);
1261         blk_mq_hctx_mark_pending(hctx, ctx);
1262 }
1263
1264 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1265                             struct list_head *list)
1266
1267 {
1268         /*
1269          * preemption doesn't flush plug list, so it's possible ctx->cpu is
1270          * offline now
1271          */
1272         spin_lock(&ctx->lock);
1273         while (!list_empty(list)) {
1274                 struct request *rq;
1275
1276                 rq = list_first_entry(list, struct request, queuelist);
1277                 BUG_ON(rq->mq_ctx != ctx);
1278                 list_del_init(&rq->queuelist);
1279                 __blk_mq_insert_req_list(hctx, rq, false);
1280         }
1281         blk_mq_hctx_mark_pending(hctx, ctx);
1282         spin_unlock(&ctx->lock);
1283 }
1284
1285 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1286 {
1287         struct request *rqa = container_of(a, struct request, queuelist);
1288         struct request *rqb = container_of(b, struct request, queuelist);
1289
1290         return !(rqa->mq_ctx < rqb->mq_ctx ||
1291                  (rqa->mq_ctx == rqb->mq_ctx &&
1292                   blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1293 }
1294
1295 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1296 {
1297         struct blk_mq_ctx *this_ctx;
1298         struct request_queue *this_q;
1299         struct request *rq;
1300         LIST_HEAD(list);
1301         LIST_HEAD(ctx_list);
1302         unsigned int depth;
1303
1304         list_splice_init(&plug->mq_list, &list);
1305
1306         list_sort(NULL, &list, plug_ctx_cmp);
1307
1308         this_q = NULL;
1309         this_ctx = NULL;
1310         depth = 0;
1311
1312         while (!list_empty(&list)) {
1313                 rq = list_entry_rq(list.next);
1314                 list_del_init(&rq->queuelist);
1315                 BUG_ON(!rq->q);
1316                 if (rq->mq_ctx != this_ctx) {
1317                         if (this_ctx) {
1318                                 trace_block_unplug(this_q, depth, from_schedule);
1319                                 blk_mq_sched_insert_requests(this_q, this_ctx,
1320                                                                 &ctx_list,
1321                                                                 from_schedule);
1322                         }
1323
1324                         this_ctx = rq->mq_ctx;
1325                         this_q = rq->q;
1326                         depth = 0;
1327                 }
1328
1329                 depth++;
1330                 list_add_tail(&rq->queuelist, &ctx_list);
1331         }
1332
1333         /*
1334          * If 'this_ctx' is set, we know we have entries to complete
1335          * on 'ctx_list'. Do those.
1336          */
1337         if (this_ctx) {
1338                 trace_block_unplug(this_q, depth, from_schedule);
1339                 blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list,
1340                                                 from_schedule);
1341         }
1342 }
1343
1344 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1345 {
1346         init_request_from_bio(rq, bio);
1347
1348         blk_account_io_start(rq, true);
1349 }
1350
1351 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
1352 {
1353         return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
1354                 !blk_queue_nomerges(hctx->queue);
1355 }
1356
1357 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
1358                                          struct blk_mq_ctx *ctx,
1359                                          struct request *rq, struct bio *bio)
1360 {
1361         if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
1362                 blk_mq_bio_to_request(rq, bio);
1363                 spin_lock(&ctx->lock);
1364 insert_rq:
1365                 __blk_mq_insert_request(hctx, rq, false);
1366                 spin_unlock(&ctx->lock);
1367                 return false;
1368         } else {
1369                 struct request_queue *q = hctx->queue;
1370
1371                 spin_lock(&ctx->lock);
1372                 if (!blk_mq_attempt_merge(q, ctx, bio)) {
1373                         blk_mq_bio_to_request(rq, bio);
1374                         goto insert_rq;
1375                 }
1376
1377                 spin_unlock(&ctx->lock);
1378                 __blk_mq_finish_request(hctx, ctx, rq);
1379                 return true;
1380         }
1381 }
1382
1383 static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
1384 {
1385         if (rq->tag != -1)
1386                 return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false);
1387
1388         return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
1389 }
1390
1391 static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie)
1392 {
1393         struct request_queue *q = rq->q;
1394         struct blk_mq_queue_data bd = {
1395                 .rq = rq,
1396                 .list = NULL,
1397                 .last = 1
1398         };
1399         struct blk_mq_hw_ctx *hctx;
1400         blk_qc_t new_cookie;
1401         int ret;
1402
1403         if (q->elevator)
1404                 goto insert;
1405
1406         if (!blk_mq_get_driver_tag(rq, &hctx, false))
1407                 goto insert;
1408
1409         new_cookie = request_to_qc_t(hctx, rq);
1410
1411         /*
1412          * For OK queue, we are done. For error, kill it. Any other
1413          * error (busy), just add it to our list as we previously
1414          * would have done
1415          */
1416         ret = q->mq_ops->queue_rq(hctx, &bd);
1417         if (ret == BLK_MQ_RQ_QUEUE_OK) {
1418                 *cookie = new_cookie;
1419                 return;
1420         }
1421
1422         __blk_mq_requeue_request(rq);
1423
1424         if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
1425                 *cookie = BLK_QC_T_NONE;
1426                 rq->errors = -EIO;
1427                 blk_mq_end_request(rq, rq->errors);
1428                 return;
1429         }
1430
1431 insert:
1432         blk_mq_sched_insert_request(rq, false, true, true, false);
1433 }
1434
1435 /*
1436  * Multiple hardware queue variant. This will not use per-process plugs,
1437  * but will attempt to bypass the hctx queueing if we can go straight to
1438  * hardware for SYNC IO.
1439  */
1440 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1441 {
1442         const int is_sync = op_is_sync(bio->bi_opf);
1443         const int is_flush_fua = op_is_flush(bio->bi_opf);
1444         struct blk_mq_alloc_data data = { .flags = 0 };
1445         struct request *rq;
1446         unsigned int request_count = 0, srcu_idx;
1447         struct blk_plug *plug;
1448         struct request *same_queue_rq = NULL;
1449         blk_qc_t cookie;
1450         unsigned int wb_acct;
1451
1452         blk_queue_bounce(q, &bio);
1453
1454         if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1455                 bio_io_error(bio);
1456                 return BLK_QC_T_NONE;
1457         }
1458
1459         blk_queue_split(q, &bio, q->bio_split);
1460
1461         if (!is_flush_fua && !blk_queue_nomerges(q) &&
1462             blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1463                 return BLK_QC_T_NONE;
1464
1465         if (blk_mq_sched_bio_merge(q, bio))
1466                 return BLK_QC_T_NONE;
1467
1468         wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1469
1470         trace_block_getrq(q, bio, bio->bi_opf);
1471
1472         rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
1473         if (unlikely(!rq)) {
1474                 __wbt_done(q->rq_wb, wb_acct);
1475                 return BLK_QC_T_NONE;
1476         }
1477
1478         wbt_track(&rq->issue_stat, wb_acct);
1479
1480         cookie = request_to_qc_t(data.hctx, rq);
1481
1482         if (unlikely(is_flush_fua)) {
1483                 if (q->elevator)
1484                         goto elv_insert;
1485                 blk_mq_bio_to_request(rq, bio);
1486                 blk_insert_flush(rq);
1487                 goto run_queue;
1488         }
1489
1490         plug = current->plug;
1491         /*
1492          * If the driver supports defer issued based on 'last', then
1493          * queue it up like normal since we can potentially save some
1494          * CPU this way.
1495          */
1496         if (((plug && !blk_queue_nomerges(q)) || is_sync) &&
1497             !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
1498                 struct request *old_rq = NULL;
1499
1500                 blk_mq_bio_to_request(rq, bio);
1501
1502                 /*
1503                  * We do limited plugging. If the bio can be merged, do that.
1504                  * Otherwise the existing request in the plug list will be
1505                  * issued. So the plug list will have one request at most
1506                  */
1507                 if (plug) {
1508                         /*
1509                          * The plug list might get flushed before this. If that
1510                          * happens, same_queue_rq is invalid and plug list is
1511                          * empty
1512                          */
1513                         if (same_queue_rq && !list_empty(&plug->mq_list)) {
1514                                 old_rq = same_queue_rq;
1515                                 list_del_init(&old_rq->queuelist);
1516                         }
1517                         list_add_tail(&rq->queuelist, &plug->mq_list);
1518                 } else /* is_sync */
1519                         old_rq = rq;
1520                 blk_mq_put_ctx(data.ctx);
1521                 if (!old_rq)
1522                         goto done;
1523
1524                 if (!(data.hctx->flags & BLK_MQ_F_BLOCKING)) {
1525                         rcu_read_lock();
1526                         blk_mq_try_issue_directly(old_rq, &cookie);
1527                         rcu_read_unlock();
1528                 } else {
1529                         srcu_idx = srcu_read_lock(&data.hctx->queue_rq_srcu);
1530                         blk_mq_try_issue_directly(old_rq, &cookie);
1531                         srcu_read_unlock(&data.hctx->queue_rq_srcu, srcu_idx);
1532                 }
1533                 goto done;
1534         }
1535
1536         if (q->elevator) {
1537 elv_insert:
1538                 blk_mq_put_ctx(data.ctx);
1539                 blk_mq_bio_to_request(rq, bio);
1540                 blk_mq_sched_insert_request(rq, false, true,
1541                                                 !is_sync || is_flush_fua, true);
1542                 goto done;
1543         }
1544         if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1545                 /*
1546                  * For a SYNC request, send it to the hardware immediately. For
1547                  * an ASYNC request, just ensure that we run it later on. The
1548                  * latter allows for merging opportunities and more efficient
1549                  * dispatching.
1550                  */
1551 run_queue:
1552                 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1553         }
1554         blk_mq_put_ctx(data.ctx);
1555 done:
1556         return cookie;
1557 }
1558
1559 /*
1560  * Single hardware queue variant. This will attempt to use any per-process
1561  * plug for merging and IO deferral.
1562  */
1563 static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
1564 {
1565         const int is_sync = op_is_sync(bio->bi_opf);
1566         const int is_flush_fua = op_is_flush(bio->bi_opf);
1567         struct blk_plug *plug;
1568         unsigned int request_count = 0;
1569         struct blk_mq_alloc_data data = { .flags = 0 };
1570         struct request *rq;
1571         blk_qc_t cookie;
1572         unsigned int wb_acct;
1573
1574         blk_queue_bounce(q, &bio);
1575
1576         if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1577                 bio_io_error(bio);
1578                 return BLK_QC_T_NONE;
1579         }
1580
1581         blk_queue_split(q, &bio, q->bio_split);
1582
1583         if (!is_flush_fua && !blk_queue_nomerges(q)) {
1584                 if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
1585                         return BLK_QC_T_NONE;
1586         } else
1587                 request_count = blk_plug_queued_count(q);
1588
1589         if (blk_mq_sched_bio_merge(q, bio))
1590                 return BLK_QC_T_NONE;
1591
1592         wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1593
1594         trace_block_getrq(q, bio, bio->bi_opf);
1595
1596         rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
1597         if (unlikely(!rq)) {
1598                 __wbt_done(q->rq_wb, wb_acct);
1599                 return BLK_QC_T_NONE;
1600         }
1601
1602         wbt_track(&rq->issue_stat, wb_acct);
1603
1604         cookie = request_to_qc_t(data.hctx, rq);
1605
1606         if (unlikely(is_flush_fua)) {
1607                 if (q->elevator)
1608                         goto elv_insert;
1609                 blk_mq_bio_to_request(rq, bio);
1610                 blk_insert_flush(rq);
1611                 goto run_queue;
1612         }
1613
1614         /*
1615          * A task plug currently exists. Since this is completely lockless,
1616          * utilize that to temporarily store requests until the task is
1617          * either done or scheduled away.
1618          */
1619         plug = current->plug;
1620         if (plug) {
1621                 struct request *last = NULL;
1622
1623                 blk_mq_bio_to_request(rq, bio);
1624
1625                 /*
1626                  * @request_count may become stale because of schedule
1627                  * out, so check the list again.
1628                  */
1629                 if (list_empty(&plug->mq_list))
1630                         request_count = 0;
1631                 if (!request_count)
1632                         trace_block_plug(q);
1633                 else
1634                         last = list_entry_rq(plug->mq_list.prev);
1635
1636                 blk_mq_put_ctx(data.ctx);
1637
1638                 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
1639                     blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
1640                         blk_flush_plug_list(plug, false);
1641                         trace_block_plug(q);
1642                 }
1643
1644                 list_add_tail(&rq->queuelist, &plug->mq_list);
1645                 return cookie;
1646         }
1647
1648         if (q->elevator) {
1649 elv_insert:
1650                 blk_mq_put_ctx(data.ctx);
1651                 blk_mq_bio_to_request(rq, bio);
1652                 blk_mq_sched_insert_request(rq, false, true,
1653                                                 !is_sync || is_flush_fua, true);
1654                 goto done;
1655         }
1656         if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1657                 /*
1658                  * For a SYNC request, send it to the hardware immediately. For
1659                  * an ASYNC request, just ensure that we run it later on. The
1660                  * latter allows for merging opportunities and more efficient
1661                  * dispatching.
1662                  */
1663 run_queue:
1664                 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1665         }
1666
1667         blk_mq_put_ctx(data.ctx);
1668 done:
1669         return cookie;
1670 }
1671
1672 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1673                      unsigned int hctx_idx)
1674 {
1675         struct page *page;
1676
1677         if (tags->rqs && set->ops->exit_request) {
1678                 int i;
1679
1680                 for (i = 0; i < tags->nr_tags; i++) {
1681                         struct request *rq = tags->static_rqs[i];
1682
1683                         if (!rq)
1684                                 continue;
1685                         set->ops->exit_request(set->driver_data, rq,
1686                                                 hctx_idx, i);
1687                         tags->static_rqs[i] = NULL;
1688                 }
1689         }
1690
1691         while (!list_empty(&tags->page_list)) {
1692                 page = list_first_entry(&tags->page_list, struct page, lru);
1693                 list_del_init(&page->lru);
1694                 /*
1695                  * Remove kmemleak object previously allocated in
1696                  * blk_mq_init_rq_map().
1697                  */
1698                 kmemleak_free(page_address(page));
1699                 __free_pages(page, page->private);
1700         }
1701 }
1702
1703 void blk_mq_free_rq_map(struct blk_mq_tags *tags)
1704 {
1705         kfree(tags->rqs);
1706         tags->rqs = NULL;
1707         kfree(tags->static_rqs);
1708         tags->static_rqs = NULL;
1709
1710         blk_mq_free_tags(tags);
1711 }
1712
1713 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
1714                                         unsigned int hctx_idx,
1715                                         unsigned int nr_tags,
1716                                         unsigned int reserved_tags)
1717 {
1718         struct blk_mq_tags *tags;
1719         int node;
1720
1721         node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1722         if (node == NUMA_NO_NODE)
1723                 node = set->numa_node;
1724
1725         tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
1726                                 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1727         if (!tags)
1728                 return NULL;
1729
1730         tags->rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1731                                  GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1732                                  node);
1733         if (!tags->rqs) {
1734                 blk_mq_free_tags(tags);
1735                 return NULL;
1736         }
1737
1738         tags->static_rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1739                                  GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1740                                  node);
1741         if (!tags->static_rqs) {
1742                 kfree(tags->rqs);
1743                 blk_mq_free_tags(tags);
1744                 return NULL;
1745         }
1746
1747         return tags;
1748 }
1749
1750 static size_t order_to_size(unsigned int order)
1751 {
1752         return (size_t)PAGE_SIZE << order;
1753 }
1754
1755 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1756                      unsigned int hctx_idx, unsigned int depth)
1757 {
1758         unsigned int i, j, entries_per_page, max_order = 4;
1759         size_t rq_size, left;
1760         int node;
1761
1762         node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1763         if (node == NUMA_NO_NODE)
1764                 node = set->numa_node;
1765
1766         INIT_LIST_HEAD(&tags->page_list);
1767
1768         /*
1769          * rq_size is the size of the request plus driver payload, rounded
1770          * to the cacheline size
1771          */
1772         rq_size = round_up(sizeof(struct request) + set->cmd_size,
1773                                 cache_line_size());
1774         left = rq_size * depth;
1775
1776         for (i = 0; i < depth; ) {
1777                 int this_order = max_order;
1778                 struct page *page;
1779                 int to_do;
1780                 void *p;
1781
1782                 while (this_order && left < order_to_size(this_order - 1))
1783                         this_order--;
1784
1785                 do {
1786                         page = alloc_pages_node(node,
1787                                 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
1788                                 this_order);
1789                         if (page)
1790                                 break;
1791                         if (!this_order--)
1792                                 break;
1793                         if (order_to_size(this_order) < rq_size)
1794                                 break;
1795                 } while (1);
1796
1797                 if (!page)
1798                         goto fail;
1799
1800                 page->private = this_order;
1801                 list_add_tail(&page->lru, &tags->page_list);
1802
1803                 p = page_address(page);
1804                 /*
1805                  * Allow kmemleak to scan these pages as they contain pointers
1806                  * to additional allocations like via ops->init_request().
1807                  */
1808                 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
1809                 entries_per_page = order_to_size(this_order) / rq_size;
1810                 to_do = min(entries_per_page, depth - i);
1811                 left -= to_do * rq_size;
1812                 for (j = 0; j < to_do; j++) {
1813                         struct request *rq = p;
1814
1815                         tags->static_rqs[i] = rq;
1816                         if (set->ops->init_request) {
1817                                 if (set->ops->init_request(set->driver_data,
1818                                                 rq, hctx_idx, i,
1819                                                 node)) {
1820                                         tags->static_rqs[i] = NULL;
1821                                         goto fail;
1822                                 }
1823                         }
1824
1825                         p += rq_size;
1826                         i++;
1827                 }
1828         }
1829         return 0;
1830
1831 fail:
1832         blk_mq_free_rqs(set, tags, hctx_idx);
1833         return -ENOMEM;
1834 }
1835
1836 /*
1837  * 'cpu' is going away. splice any existing rq_list entries from this
1838  * software queue to the hw queue dispatch list, and ensure that it
1839  * gets run.
1840  */
1841 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
1842 {
1843         struct blk_mq_hw_ctx *hctx;
1844         struct blk_mq_ctx *ctx;
1845         LIST_HEAD(tmp);
1846
1847         hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
1848         ctx = __blk_mq_get_ctx(hctx->queue, cpu);
1849
1850         spin_lock(&ctx->lock);
1851         if (!list_empty(&ctx->rq_list)) {
1852                 list_splice_init(&ctx->rq_list, &tmp);
1853                 blk_mq_hctx_clear_pending(hctx, ctx);
1854         }
1855         spin_unlock(&ctx->lock);
1856
1857         if (list_empty(&tmp))
1858                 return 0;
1859
1860         spin_lock(&hctx->lock);
1861         list_splice_tail_init(&tmp, &hctx->dispatch);
1862         spin_unlock(&hctx->lock);
1863
1864         blk_mq_run_hw_queue(hctx, true);
1865         return 0;
1866 }
1867
1868 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
1869 {
1870         cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
1871                                             &hctx->cpuhp_dead);
1872 }
1873
1874 /* hctx->ctxs will be freed in queue's release handler */
1875 static void blk_mq_exit_hctx(struct request_queue *q,
1876                 struct blk_mq_tag_set *set,
1877                 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1878 {
1879         unsigned flush_start_tag = set->queue_depth;
1880
1881         blk_mq_tag_idle(hctx);
1882
1883         if (set->ops->exit_request)
1884                 set->ops->exit_request(set->driver_data,
1885                                        hctx->fq->flush_rq, hctx_idx,
1886                                        flush_start_tag + hctx_idx);
1887
1888         if (set->ops->exit_hctx)
1889                 set->ops->exit_hctx(hctx, hctx_idx);
1890
1891         if (hctx->flags & BLK_MQ_F_BLOCKING)
1892                 cleanup_srcu_struct(&hctx->queue_rq_srcu);
1893
1894         blk_mq_remove_cpuhp(hctx);
1895         blk_free_flush_queue(hctx->fq);
1896         sbitmap_free(&hctx->ctx_map);
1897 }
1898
1899 static void blk_mq_exit_hw_queues(struct request_queue *q,
1900                 struct blk_mq_tag_set *set, int nr_queue)
1901 {
1902         struct blk_mq_hw_ctx *hctx;
1903         unsigned int i;
1904
1905         queue_for_each_hw_ctx(q, hctx, i) {
1906                 if (i == nr_queue)
1907                         break;
1908                 blk_mq_exit_hctx(q, set, hctx, i);
1909         }
1910 }
1911
1912 static void blk_mq_free_hw_queues(struct request_queue *q,
1913                 struct blk_mq_tag_set *set)
1914 {
1915         struct blk_mq_hw_ctx *hctx;
1916         unsigned int i;
1917
1918         queue_for_each_hw_ctx(q, hctx, i)
1919                 free_cpumask_var(hctx->cpumask);
1920 }
1921
1922 static int blk_mq_init_hctx(struct request_queue *q,
1923                 struct blk_mq_tag_set *set,
1924                 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
1925 {
1926         int node;
1927         unsigned flush_start_tag = set->queue_depth;
1928
1929         node = hctx->numa_node;
1930         if (node == NUMA_NO_NODE)
1931                 node = hctx->numa_node = set->numa_node;
1932
1933         INIT_WORK(&hctx->run_work, blk_mq_run_work_fn);
1934         INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
1935         spin_lock_init(&hctx->lock);
1936         INIT_LIST_HEAD(&hctx->dispatch);
1937         hctx->queue = q;
1938         hctx->queue_num = hctx_idx;
1939         hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
1940
1941         cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
1942
1943         hctx->tags = set->tags[hctx_idx];
1944
1945         /*
1946          * Allocate space for all possible cpus to avoid allocation at
1947          * runtime
1948          */
1949         hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1950                                         GFP_KERNEL, node);
1951         if (!hctx->ctxs)
1952                 goto unregister_cpu_notifier;
1953
1954         if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
1955                               node))
1956                 goto free_ctxs;
1957
1958         hctx->nr_ctx = 0;
1959
1960         if (set->ops->init_hctx &&
1961             set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
1962                 goto free_bitmap;
1963
1964         hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
1965         if (!hctx->fq)
1966                 goto exit_hctx;
1967
1968         if (set->ops->init_request &&
1969             set->ops->init_request(set->driver_data,
1970                                    hctx->fq->flush_rq, hctx_idx,
1971                                    flush_start_tag + hctx_idx, node))
1972                 goto free_fq;
1973
1974         if (hctx->flags & BLK_MQ_F_BLOCKING)
1975                 init_srcu_struct(&hctx->queue_rq_srcu);
1976
1977         return 0;
1978
1979  free_fq:
1980         kfree(hctx->fq);
1981  exit_hctx:
1982         if (set->ops->exit_hctx)
1983                 set->ops->exit_hctx(hctx, hctx_idx);
1984  free_bitmap:
1985         sbitmap_free(&hctx->ctx_map);
1986  free_ctxs:
1987         kfree(hctx->ctxs);
1988  unregister_cpu_notifier:
1989         blk_mq_remove_cpuhp(hctx);
1990         return -1;
1991 }
1992
1993 static void blk_mq_init_cpu_queues(struct request_queue *q,
1994                                    unsigned int nr_hw_queues)
1995 {
1996         unsigned int i;
1997
1998         for_each_possible_cpu(i) {
1999                 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
2000                 struct blk_mq_hw_ctx *hctx;
2001
2002                 memset(__ctx, 0, sizeof(*__ctx));
2003                 __ctx->cpu = i;
2004                 spin_lock_init(&__ctx->lock);
2005                 INIT_LIST_HEAD(&__ctx->rq_list);
2006                 __ctx->queue = q;
2007                 blk_stat_init(&__ctx->stat[BLK_STAT_READ]);
2008                 blk_stat_init(&__ctx->stat[BLK_STAT_WRITE]);
2009
2010                 /* If the cpu isn't online, the cpu is mapped to first hctx */
2011                 if (!cpu_online(i))
2012                         continue;
2013
2014                 hctx = blk_mq_map_queue(q, i);
2015
2016                 /*
2017                  * Set local node, IFF we have more than one hw queue. If
2018                  * not, we remain on the home node of the device
2019                  */
2020                 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
2021                         hctx->numa_node = local_memory_node(cpu_to_node(i));
2022         }
2023 }
2024
2025 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
2026 {
2027         int ret = 0;
2028
2029         set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2030                                         set->queue_depth, set->reserved_tags);
2031         if (!set->tags[hctx_idx])
2032                 return false;
2033
2034         ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2035                                 set->queue_depth);
2036         if (!ret)
2037                 return true;
2038
2039         blk_mq_free_rq_map(set->tags[hctx_idx]);
2040         set->tags[hctx_idx] = NULL;
2041         return false;
2042 }
2043
2044 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2045                                          unsigned int hctx_idx)
2046 {
2047         if (set->tags[hctx_idx]) {
2048                 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2049                 blk_mq_free_rq_map(set->tags[hctx_idx]);
2050                 set->tags[hctx_idx] = NULL;
2051         }
2052 }
2053
2054 static void blk_mq_map_swqueue(struct request_queue *q,
2055                                const struct cpumask *online_mask)
2056 {
2057         unsigned int i, hctx_idx;
2058         struct blk_mq_hw_ctx *hctx;
2059         struct blk_mq_ctx *ctx;
2060         struct blk_mq_tag_set *set = q->tag_set;
2061
2062         /*
2063          * Avoid others reading imcomplete hctx->cpumask through sysfs
2064          */
2065         mutex_lock(&q->sysfs_lock);
2066
2067         queue_for_each_hw_ctx(q, hctx, i) {
2068                 cpumask_clear(hctx->cpumask);
2069                 hctx->nr_ctx = 0;
2070         }
2071
2072         /*
2073          * Map software to hardware queues
2074          */
2075         for_each_possible_cpu(i) {
2076                 /* If the cpu isn't online, the cpu is mapped to first hctx */
2077                 if (!cpumask_test_cpu(i, online_mask))
2078                         continue;
2079
2080                 hctx_idx = q->mq_map[i];
2081                 /* unmapped hw queue can be remapped after CPU topo changed */
2082                 if (!set->tags[hctx_idx] &&
2083                     !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2084                         /*
2085                          * If tags initialization fail for some hctx,
2086                          * that hctx won't be brought online.  In this
2087                          * case, remap the current ctx to hctx[0] which
2088                          * is guaranteed to always have tags allocated
2089                          */
2090                         q->mq_map[i] = 0;
2091                 }
2092
2093                 ctx = per_cpu_ptr(q->queue_ctx, i);
2094                 hctx = blk_mq_map_queue(q, i);
2095
2096                 cpumask_set_cpu(i, hctx->cpumask);
2097                 ctx->index_hw = hctx->nr_ctx;
2098                 hctx->ctxs[hctx->nr_ctx++] = ctx;
2099         }
2100
2101         mutex_unlock(&q->sysfs_lock);
2102
2103         queue_for_each_hw_ctx(q, hctx, i) {
2104                 /*
2105                  * If no software queues are mapped to this hardware queue,
2106                  * disable it and free the request entries.
2107                  */
2108                 if (!hctx->nr_ctx) {
2109                         /* Never unmap queue 0.  We need it as a
2110                          * fallback in case of a new remap fails
2111                          * allocation
2112                          */
2113                         if (i && set->tags[i])
2114                                 blk_mq_free_map_and_requests(set, i);
2115
2116                         hctx->tags = NULL;
2117                         continue;
2118                 }
2119
2120                 hctx->tags = set->tags[i];
2121                 WARN_ON(!hctx->tags);
2122
2123                 /*
2124                  * Set the map size to the number of mapped software queues.
2125                  * This is more accurate and more efficient than looping
2126                  * over all possibly mapped software queues.
2127                  */
2128                 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2129
2130                 /*
2131                  * Initialize batch roundrobin counts
2132                  */
2133                 hctx->next_cpu = cpumask_first(hctx->cpumask);
2134                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2135         }
2136 }
2137
2138 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2139 {
2140         struct blk_mq_hw_ctx *hctx;
2141         int i;
2142
2143         queue_for_each_hw_ctx(q, hctx, i) {
2144                 if (shared)
2145                         hctx->flags |= BLK_MQ_F_TAG_SHARED;
2146                 else
2147                         hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2148         }
2149 }
2150
2151 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
2152 {
2153         struct request_queue *q;
2154
2155         list_for_each_entry(q, &set->tag_list, tag_set_list) {
2156                 blk_mq_freeze_queue(q);
2157                 queue_set_hctx_shared(q, shared);
2158                 blk_mq_unfreeze_queue(q);
2159         }
2160 }
2161
2162 static void blk_mq_del_queue_tag_set(struct request_queue *q)
2163 {
2164         struct blk_mq_tag_set *set = q->tag_set;
2165
2166         mutex_lock(&set->tag_list_lock);
2167         list_del_init(&q->tag_set_list);
2168         if (list_is_singular(&set->tag_list)) {
2169                 /* just transitioned to unshared */
2170                 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2171                 /* update existing queue */
2172                 blk_mq_update_tag_set_depth(set, false);
2173         }
2174         mutex_unlock(&set->tag_list_lock);
2175 }
2176
2177 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2178                                      struct request_queue *q)
2179 {
2180         q->tag_set = set;
2181
2182         mutex_lock(&set->tag_list_lock);
2183
2184         /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2185         if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2186                 set->flags |= BLK_MQ_F_TAG_SHARED;
2187                 /* update existing queue */
2188                 blk_mq_update_tag_set_depth(set, true);
2189         }
2190         if (set->flags & BLK_MQ_F_TAG_SHARED)
2191                 queue_set_hctx_shared(q, true);
2192         list_add_tail(&q->tag_set_list, &set->tag_list);
2193
2194         mutex_unlock(&set->tag_list_lock);
2195 }
2196
2197 /*
2198  * It is the actual release handler for mq, but we do it from
2199  * request queue's release handler for avoiding use-after-free
2200  * and headache because q->mq_kobj shouldn't have been introduced,
2201  * but we can't group ctx/kctx kobj without it.
2202  */
2203 void blk_mq_release(struct request_queue *q)
2204 {
2205         struct blk_mq_hw_ctx *hctx;
2206         unsigned int i;
2207
2208         blk_mq_sched_teardown(q);
2209
2210         /* hctx kobj stays in hctx */
2211         queue_for_each_hw_ctx(q, hctx, i) {
2212                 if (!hctx)
2213                         continue;
2214                 kfree(hctx->ctxs);
2215                 kfree(hctx);
2216         }
2217
2218         q->mq_map = NULL;
2219
2220         kfree(q->queue_hw_ctx);
2221
2222         /* ctx kobj stays in queue_ctx */
2223         free_percpu(q->queue_ctx);
2224 }
2225
2226 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2227 {
2228         struct request_queue *uninit_q, *q;
2229
2230         uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
2231         if (!uninit_q)
2232                 return ERR_PTR(-ENOMEM);
2233
2234         q = blk_mq_init_allocated_queue(set, uninit_q);
2235         if (IS_ERR(q))
2236                 blk_cleanup_queue(uninit_q);
2237
2238         return q;
2239 }
2240 EXPORT_SYMBOL(blk_mq_init_queue);
2241
2242 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2243                                                 struct request_queue *q)
2244 {
2245         int i, j;
2246         struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2247
2248         blk_mq_sysfs_unregister(q);
2249         for (i = 0; i < set->nr_hw_queues; i++) {
2250                 int node;
2251
2252                 if (hctxs[i])
2253                         continue;
2254
2255                 node = blk_mq_hw_queue_to_node(q->mq_map, i);
2256                 hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
2257                                         GFP_KERNEL, node);
2258                 if (!hctxs[i])
2259                         break;
2260
2261                 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
2262                                                 node)) {
2263                         kfree(hctxs[i]);
2264                         hctxs[i] = NULL;
2265                         break;
2266                 }
2267
2268                 atomic_set(&hctxs[i]->nr_active, 0);
2269                 hctxs[i]->numa_node = node;
2270                 hctxs[i]->queue_num = i;
2271
2272                 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
2273                         free_cpumask_var(hctxs[i]->cpumask);
2274                         kfree(hctxs[i]);
2275                         hctxs[i] = NULL;
2276                         break;
2277                 }
2278                 blk_mq_hctx_kobj_init(hctxs[i]);
2279         }
2280         for (j = i; j < q->nr_hw_queues; j++) {
2281                 struct blk_mq_hw_ctx *hctx = hctxs[j];
2282
2283                 if (hctx) {
2284                         if (hctx->tags)
2285                                 blk_mq_free_map_and_requests(set, j);
2286                         blk_mq_exit_hctx(q, set, hctx, j);
2287                         free_cpumask_var(hctx->cpumask);
2288                         kobject_put(&hctx->kobj);
2289                         kfree(hctx->ctxs);
2290                         kfree(hctx);
2291                         hctxs[j] = NULL;
2292
2293                 }
2294         }
2295         q->nr_hw_queues = i;
2296         blk_mq_sysfs_register(q);
2297 }
2298
2299 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2300                                                   struct request_queue *q)
2301 {
2302         /* mark the queue as mq asap */
2303         q->mq_ops = set->ops;
2304
2305         q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2306         if (!q->queue_ctx)
2307                 goto err_exit;
2308
2309         q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
2310                                                 GFP_KERNEL, set->numa_node);
2311         if (!q->queue_hw_ctx)
2312                 goto err_percpu;
2313
2314         q->mq_map = set->mq_map;
2315
2316         blk_mq_realloc_hw_ctxs(set, q);
2317         if (!q->nr_hw_queues)
2318                 goto err_hctxs;
2319
2320         INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2321         blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2322
2323         q->nr_queues = nr_cpu_ids;
2324
2325         q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2326
2327         if (!(set->flags & BLK_MQ_F_SG_MERGE))
2328                 q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
2329
2330         q->sg_reserved_size = INT_MAX;
2331
2332         INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2333         INIT_LIST_HEAD(&q->requeue_list);
2334         spin_lock_init(&q->requeue_lock);
2335
2336         if (q->nr_hw_queues > 1)
2337                 blk_queue_make_request(q, blk_mq_make_request);
2338         else
2339                 blk_queue_make_request(q, blk_sq_make_request);
2340
2341         /*
2342          * Do this after blk_queue_make_request() overrides it...
2343          */
2344         q->nr_requests = set->queue_depth;
2345
2346         /*
2347          * Default to classic polling
2348          */
2349         q->poll_nsec = -1;
2350
2351         if (set->ops->complete)
2352                 blk_queue_softirq_done(q, set->ops->complete);
2353
2354         blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2355
2356         get_online_cpus();
2357         mutex_lock(&all_q_mutex);
2358
2359         list_add_tail(&q->all_q_node, &all_q_list);
2360         blk_mq_add_queue_tag_set(set, q);
2361         blk_mq_map_swqueue(q, cpu_online_mask);
2362
2363         mutex_unlock(&all_q_mutex);
2364         put_online_cpus();
2365
2366         if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
2367                 int ret;
2368
2369                 ret = blk_mq_sched_init(q);
2370                 if (ret)
2371                         return ERR_PTR(ret);
2372         }
2373
2374         return q;
2375
2376 err_hctxs:
2377         kfree(q->queue_hw_ctx);
2378 err_percpu:
2379         free_percpu(q->queue_ctx);
2380 err_exit:
2381         q->mq_ops = NULL;
2382         return ERR_PTR(-ENOMEM);
2383 }
2384 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2385
2386 void blk_mq_free_queue(struct request_queue *q)
2387 {
2388         struct blk_mq_tag_set   *set = q->tag_set;
2389
2390         mutex_lock(&all_q_mutex);
2391         list_del_init(&q->all_q_node);
2392         mutex_unlock(&all_q_mutex);
2393
2394         wbt_exit(q);
2395
2396         blk_mq_del_queue_tag_set(q);
2397
2398         blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2399         blk_mq_free_hw_queues(q, set);
2400 }
2401
2402 /* Basically redo blk_mq_init_queue with queue frozen */
2403 static void blk_mq_queue_reinit(struct request_queue *q,
2404                                 const struct cpumask *online_mask)
2405 {
2406         WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2407
2408         blk_mq_sysfs_unregister(q);
2409
2410         /*
2411          * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2412          * we should change hctx numa_node according to new topology (this
2413          * involves free and re-allocate memory, worthy doing?)
2414          */
2415
2416         blk_mq_map_swqueue(q, online_mask);
2417
2418         blk_mq_sysfs_register(q);
2419 }
2420
2421 /*
2422  * New online cpumask which is going to be set in this hotplug event.
2423  * Declare this cpumasks as global as cpu-hotplug operation is invoked
2424  * one-by-one and dynamically allocating this could result in a failure.
2425  */
2426 static struct cpumask cpuhp_online_new;
2427
2428 static void blk_mq_queue_reinit_work(void)
2429 {
2430         struct request_queue *q;
2431
2432         mutex_lock(&all_q_mutex);
2433         /*
2434          * We need to freeze and reinit all existing queues.  Freezing
2435          * involves synchronous wait for an RCU grace period and doing it
2436          * one by one may take a long time.  Start freezing all queues in
2437          * one swoop and then wait for the completions so that freezing can
2438          * take place in parallel.
2439          */
2440         list_for_each_entry(q, &all_q_list, all_q_node)
2441                 blk_mq_freeze_queue_start(q);
2442         list_for_each_entry(q, &all_q_list, all_q_node)
2443                 blk_mq_freeze_queue_wait(q);
2444
2445         list_for_each_entry(q, &all_q_list, all_q_node)
2446                 blk_mq_queue_reinit(q, &cpuhp_online_new);
2447
2448         list_for_each_entry(q, &all_q_list, all_q_node)
2449                 blk_mq_unfreeze_queue(q);
2450
2451         mutex_unlock(&all_q_mutex);
2452 }
2453
2454 static int blk_mq_queue_reinit_dead(unsigned int cpu)
2455 {
2456         cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2457         blk_mq_queue_reinit_work();
2458         return 0;
2459 }
2460
2461 /*
2462  * Before hotadded cpu starts handling requests, new mappings must be
2463  * established.  Otherwise, these requests in hw queue might never be
2464  * dispatched.
2465  *
2466  * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2467  * for CPU0, and ctx1 for CPU1).
2468  *
2469  * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2470  * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2471  *
2472  * And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
2473  * in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2474  * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
2475  * ignored.
2476  */
2477 static int blk_mq_queue_reinit_prepare(unsigned int cpu)
2478 {
2479         cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2480         cpumask_set_cpu(cpu, &cpuhp_online_new);
2481         blk_mq_queue_reinit_work();
2482         return 0;
2483 }
2484
2485 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2486 {
2487         int i;
2488
2489         for (i = 0; i < set->nr_hw_queues; i++)
2490                 if (!__blk_mq_alloc_rq_map(set, i))
2491                         goto out_unwind;
2492
2493         return 0;
2494
2495 out_unwind:
2496         while (--i >= 0)
2497                 blk_mq_free_rq_map(set->tags[i]);
2498
2499         return -ENOMEM;
2500 }
2501
2502 /*
2503  * Allocate the request maps associated with this tag_set. Note that this
2504  * may reduce the depth asked for, if memory is tight. set->queue_depth
2505  * will be updated to reflect the allocated depth.
2506  */
2507 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2508 {
2509         unsigned int depth;
2510         int err;
2511
2512         depth = set->queue_depth;
2513         do {
2514                 err = __blk_mq_alloc_rq_maps(set);
2515                 if (!err)
2516                         break;
2517
2518                 set->queue_depth >>= 1;
2519                 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2520                         err = -ENOMEM;
2521                         break;
2522                 }
2523         } while (set->queue_depth);
2524
2525         if (!set->queue_depth || err) {
2526                 pr_err("blk-mq: failed to allocate request map\n");
2527                 return -ENOMEM;
2528         }
2529
2530         if (depth != set->queue_depth)
2531                 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2532                                                 depth, set->queue_depth);
2533
2534         return 0;
2535 }
2536
2537 /*
2538  * Alloc a tag set to be associated with one or more request queues.
2539  * May fail with EINVAL for various error conditions. May adjust the
2540  * requested depth down, if if it too large. In that case, the set
2541  * value will be stored in set->queue_depth.
2542  */
2543 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2544 {
2545         int ret;
2546
2547         BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2548
2549         if (!set->nr_hw_queues)
2550                 return -EINVAL;
2551         if (!set->queue_depth)
2552                 return -EINVAL;
2553         if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2554                 return -EINVAL;
2555
2556         if (!set->ops->queue_rq)
2557                 return -EINVAL;
2558
2559         if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2560                 pr_info("blk-mq: reduced tag depth to %u\n",
2561                         BLK_MQ_MAX_DEPTH);
2562                 set->queue_depth = BLK_MQ_MAX_DEPTH;
2563         }
2564
2565         /*
2566          * If a crashdump is active, then we are potentially in a very
2567          * memory constrained environment. Limit us to 1 queue and
2568          * 64 tags to prevent using too much memory.
2569          */
2570         if (is_kdump_kernel()) {
2571                 set->nr_hw_queues = 1;
2572                 set->queue_depth = min(64U, set->queue_depth);
2573         }
2574         /*
2575          * There is no use for more h/w queues than cpus.
2576          */
2577         if (set->nr_hw_queues > nr_cpu_ids)
2578                 set->nr_hw_queues = nr_cpu_ids;
2579
2580         set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2581                                  GFP_KERNEL, set->numa_node);
2582         if (!set->tags)
2583                 return -ENOMEM;
2584
2585         ret = -ENOMEM;
2586         set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
2587                         GFP_KERNEL, set->numa_node);
2588         if (!set->mq_map)
2589                 goto out_free_tags;
2590
2591         if (set->ops->map_queues)
2592                 ret = set->ops->map_queues(set);
2593         else
2594                 ret = blk_mq_map_queues(set);
2595         if (ret)
2596                 goto out_free_mq_map;
2597
2598         ret = blk_mq_alloc_rq_maps(set);
2599         if (ret)
2600                 goto out_free_mq_map;
2601
2602         mutex_init(&set->tag_list_lock);
2603         INIT_LIST_HEAD(&set->tag_list);
2604
2605         return 0;
2606
2607 out_free_mq_map:
2608         kfree(set->mq_map);
2609         set->mq_map = NULL;
2610 out_free_tags:
2611         kfree(set->tags);
2612         set->tags = NULL;
2613         return ret;
2614 }
2615 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2616
2617 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2618 {
2619         int i;
2620
2621         for (i = 0; i < nr_cpu_ids; i++)
2622                 blk_mq_free_map_and_requests(set, i);
2623
2624         kfree(set->mq_map);
2625         set->mq_map = NULL;
2626
2627         kfree(set->tags);
2628         set->tags = NULL;
2629 }
2630 EXPORT_SYMBOL(blk_mq_free_tag_set);
2631
2632 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2633 {
2634         struct blk_mq_tag_set *set = q->tag_set;
2635         struct blk_mq_hw_ctx *hctx;
2636         int i, ret;
2637
2638         if (!set)
2639                 return -EINVAL;
2640
2641         blk_mq_freeze_queue(q);
2642         blk_mq_quiesce_queue(q);
2643
2644         ret = 0;
2645         queue_for_each_hw_ctx(q, hctx, i) {
2646                 if (!hctx->tags)
2647                         continue;
2648                 /*
2649                  * If we're using an MQ scheduler, just update the scheduler
2650                  * queue depth. This is similar to what the old code would do.
2651                  */
2652                 if (!hctx->sched_tags) {
2653                         ret = blk_mq_tag_update_depth(hctx, &hctx->tags,
2654                                                         min(nr, set->queue_depth),
2655                                                         false);
2656                 } else {
2657                         ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
2658                                                         nr, true);
2659                 }
2660                 if (ret)
2661                         break;
2662         }
2663
2664         if (!ret)
2665                 q->nr_requests = nr;
2666
2667         blk_mq_unfreeze_queue(q);
2668         blk_mq_start_stopped_hw_queues(q, true);
2669
2670         return ret;
2671 }
2672
2673 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2674 {
2675         struct request_queue *q;
2676
2677         if (nr_hw_queues > nr_cpu_ids)
2678                 nr_hw_queues = nr_cpu_ids;
2679         if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2680                 return;
2681
2682         list_for_each_entry(q, &set->tag_list, tag_set_list)
2683                 blk_mq_freeze_queue(q);
2684
2685         set->nr_hw_queues = nr_hw_queues;
2686         list_for_each_entry(q, &set->tag_list, tag_set_list) {
2687                 blk_mq_realloc_hw_ctxs(set, q);
2688
2689                 /*
2690                  * Manually set the make_request_fn as blk_queue_make_request
2691                  * resets a lot of the queue settings.
2692                  */
2693                 if (q->nr_hw_queues > 1)
2694                         q->make_request_fn = blk_mq_make_request;
2695                 else
2696                         q->make_request_fn = blk_sq_make_request;
2697
2698                 blk_mq_queue_reinit(q, cpu_online_mask);
2699         }
2700
2701         list_for_each_entry(q, &set->tag_list, tag_set_list)
2702                 blk_mq_unfreeze_queue(q);
2703 }
2704 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2705
2706 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
2707                                        struct blk_mq_hw_ctx *hctx,
2708                                        struct request *rq)
2709 {
2710         struct blk_rq_stat stat[2];
2711         unsigned long ret = 0;
2712
2713         /*
2714          * If stats collection isn't on, don't sleep but turn it on for
2715          * future users
2716          */
2717         if (!blk_stat_enable(q))
2718                 return 0;
2719
2720         /*
2721          * We don't have to do this once per IO, should optimize this
2722          * to just use the current window of stats until it changes
2723          */
2724         memset(&stat, 0, sizeof(stat));
2725         blk_hctx_stat_get(hctx, stat);
2726
2727         /*
2728          * As an optimistic guess, use half of the mean service time
2729          * for this type of request. We can (and should) make this smarter.
2730          * For instance, if the completion latencies are tight, we can
2731          * get closer than just half the mean. This is especially
2732          * important on devices where the completion latencies are longer
2733          * than ~10 usec.
2734          */
2735         if (req_op(rq) == REQ_OP_READ && stat[BLK_STAT_READ].nr_samples)
2736                 ret = (stat[BLK_STAT_READ].mean + 1) / 2;
2737         else if (req_op(rq) == REQ_OP_WRITE && stat[BLK_STAT_WRITE].nr_samples)
2738                 ret = (stat[BLK_STAT_WRITE].mean + 1) / 2;
2739
2740         return ret;
2741 }
2742
2743 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
2744                                      struct blk_mq_hw_ctx *hctx,
2745                                      struct request *rq)
2746 {
2747         struct hrtimer_sleeper hs;
2748         enum hrtimer_mode mode;
2749         unsigned int nsecs;
2750         ktime_t kt;
2751
2752         if (test_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags))
2753                 return false;
2754
2755         /*
2756          * poll_nsec can be:
2757          *
2758          * -1:  don't ever hybrid sleep
2759          *  0:  use half of prev avg
2760          * >0:  use this specific value
2761          */
2762         if (q->poll_nsec == -1)
2763                 return false;
2764         else if (q->poll_nsec > 0)
2765                 nsecs = q->poll_nsec;
2766         else
2767                 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
2768
2769         if (!nsecs)
2770                 return false;
2771
2772         set_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
2773
2774         /*
2775          * This will be replaced with the stats tracking code, using
2776          * 'avg_completion_time / 2' as the pre-sleep target.
2777          */
2778         kt = nsecs;
2779
2780         mode = HRTIMER_MODE_REL;
2781         hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
2782         hrtimer_set_expires(&hs.timer, kt);
2783
2784         hrtimer_init_sleeper(&hs, current);
2785         do {
2786                 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
2787                         break;
2788                 set_current_state(TASK_UNINTERRUPTIBLE);
2789                 hrtimer_start_expires(&hs.timer, mode);
2790                 if (hs.task)
2791                         io_schedule();
2792                 hrtimer_cancel(&hs.timer);
2793                 mode = HRTIMER_MODE_ABS;
2794         } while (hs.task && !signal_pending(current));
2795
2796         __set_current_state(TASK_RUNNING);
2797         destroy_hrtimer_on_stack(&hs.timer);
2798         return true;
2799 }
2800
2801 static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
2802 {
2803         struct request_queue *q = hctx->queue;
2804         long state;
2805
2806         /*
2807          * If we sleep, have the caller restart the poll loop to reset
2808          * the state. Like for the other success return cases, the
2809          * caller is responsible for checking if the IO completed. If
2810          * the IO isn't complete, we'll get called again and will go
2811          * straight to the busy poll loop.
2812          */
2813         if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
2814                 return true;
2815
2816         hctx->poll_considered++;
2817
2818         state = current->state;
2819         while (!need_resched()) {
2820                 int ret;
2821
2822                 hctx->poll_invoked++;
2823
2824                 ret = q->mq_ops->poll(hctx, rq->tag);
2825                 if (ret > 0) {
2826                         hctx->poll_success++;
2827                         set_current_state(TASK_RUNNING);
2828                         return true;
2829                 }
2830
2831                 if (signal_pending_state(state, current))
2832                         set_current_state(TASK_RUNNING);
2833
2834                 if (current->state == TASK_RUNNING)
2835                         return true;
2836                 if (ret < 0)
2837                         break;
2838                 cpu_relax();
2839         }
2840
2841         return false;
2842 }
2843
2844 bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
2845 {
2846         struct blk_mq_hw_ctx *hctx;
2847         struct blk_plug *plug;
2848         struct request *rq;
2849
2850         if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) ||
2851             !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
2852                 return false;
2853
2854         plug = current->plug;
2855         if (plug)
2856                 blk_flush_plug_list(plug, false);
2857
2858         hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
2859         if (!blk_qc_t_is_internal(cookie))
2860                 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
2861         else
2862                 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
2863
2864         return __blk_mq_poll(hctx, rq);
2865 }
2866 EXPORT_SYMBOL_GPL(blk_mq_poll);
2867
2868 void blk_mq_disable_hotplug(void)
2869 {
2870         mutex_lock(&all_q_mutex);
2871 }
2872
2873 void blk_mq_enable_hotplug(void)
2874 {
2875         mutex_unlock(&all_q_mutex);
2876 }
2877
2878 static int __init blk_mq_init(void)
2879 {
2880         cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
2881                                 blk_mq_hctx_notify_dead);
2882
2883         cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE, "block/mq:prepare",
2884                                   blk_mq_queue_reinit_prepare,
2885                                   blk_mq_queue_reinit_dead);
2886         return 0;
2887 }
2888 subsys_initcall(blk_mq_init);