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