block/blk-mq.c

   1 /*
   2  * Block multiqueue core code
   3  *
   4  * Copyright (C) 2013-2014 Jens Axboe
   5  * Copyright (C) 2013-2014 Christoph Hellwig
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/backing-dev.h>
  10 #include <linux/bio.h>
  11 #include <linux/blkdev.h>
  12 #include <linux/kmemleak.h>
  13 #include <linux/mm.h>
  14 #include <linux/init.h>
  15 #include <linux/slab.h>
  16 #include <linux/workqueue.h>
  17 #include <linux/smp.h>
  18 #include <linux/llist.h>
  19 #include <linux/list_sort.h>
  20 #include <linux/cpu.h>
  21 #include <linux/cache.h>
  22 #include <linux/sched/sysctl.h>
  23 #include <linux/delay.h>
  24 #include <linux/crash_dump.h>
  25 #include <linux/prefetch.h>
  26
  27 #include <trace/events/block.h>
  28
  29 #include <linux/blk-mq.h>
  30 #include "blk.h"
  31 #include "blk-mq.h"
  32 #include "blk-mq-tag.h"
  33
  34 static DEFINE_MUTEX(all_q_mutex);
  35 static LIST_HEAD(all_q_list);
  36
  37 /*
  38  * Check if any of the ctx's have pending work in this hardware queue
  39  */
  40 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
  41 {
  42         return sbitmap_any_bit_set(&hctx->ctx_map);
  43 }
  44
  45 /*
  46  * Mark this ctx as having pending work in this hardware queue
  47  */
  48 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
  49                                      struct blk_mq_ctx *ctx)
  50 {
  51         if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
  52                 sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
  53 }
  54
  55 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
  56                                       struct blk_mq_ctx *ctx)
  57 {
  58         sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
  59 }
  60
  61 void blk_mq_freeze_queue_start(struct request_queue *q)
  62 {
  63         int freeze_depth;
  64
  65         freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
  66         if (freeze_depth == 1) {
  67                 percpu_ref_kill(&q->q_usage_counter);
  68                 blk_mq_run_hw_queues(q, false);
  69         }
  70 }
  71 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
  72
  73 static void blk_mq_freeze_queue_wait(struct request_queue *q)
  74 {
  75         wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
  76 }
  77
  78 /*
  79  * Guarantee no request is in use, so we can change any data structure of
  80  * the queue afterward.
  81  */
  82 void blk_freeze_queue(struct request_queue *q)
  83 {
  84         /*
  85          * In the !blk_mq case we are only calling this to kill the
  86          * q_usage_counter, otherwise this increases the freeze depth
  87          * and waits for it to return to zero.  For this reason there is
  88          * no blk_unfreeze_queue(), and blk_freeze_queue() is not
  89          * exported to drivers as the only user for unfreeze is blk_mq.
  90          */
  91         blk_mq_freeze_queue_start(q);
  92         blk_mq_freeze_queue_wait(q);
  93 }
  94
  95 void blk_mq_freeze_queue(struct request_queue *q)
  96 {
  97         /*
  98          * ...just an alias to keep freeze and unfreeze actions balanced
  99          * in the blk_mq_* namespace
 100          */
 101         blk_freeze_queue(q);
 102 }
 103 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
 104
 105 void blk_mq_unfreeze_queue(struct request_queue *q)
 106 {
 107         int freeze_depth;
 108
 109         freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
 110         WARN_ON_ONCE(freeze_depth < 0);
 111         if (!freeze_depth) {
 112                 percpu_ref_reinit(&q->q_usage_counter);
 113                 wake_up_all(&q->mq_freeze_wq);
 114         }
 115 }
 116 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
 117
 118 void blk_mq_wake_waiters(struct request_queue *q)
 119 {
 120         struct blk_mq_hw_ctx *hctx;
 121         unsigned int i;
 122
 123         queue_for_each_hw_ctx(q, hctx, i)
 124                 if (blk_mq_hw_queue_mapped(hctx))
 125                         blk_mq_tag_wakeup_all(hctx->tags, true);
 126
 127         /*
 128          * If we are called because the queue has now been marked as
 129          * dying, we need to ensure that processes currently waiting on
 130          * the queue are notified as well.
 131          */
 132         wake_up_all(&q->mq_freeze_wq);
 133 }
 134
 135 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
 136 {
 137         return blk_mq_has_free_tags(hctx->tags);
 138 }
 139 EXPORT_SYMBOL(blk_mq_can_queue);
 140
 141 static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
 142                                struct request *rq, int op,
 143                                unsigned int op_flags)
 144 {
 145         if (blk_queue_io_stat(q))
 146                 op_flags |= REQ_IO_STAT;
 147
 148         INIT_LIST_HEAD(&rq->queuelist);
 149         /* csd/requeue_work/fifo_time is initialized before use */
 150         rq->q = q;
 151         rq->mq_ctx = ctx;
 152         req_set_op_attrs(rq, op, op_flags);
 153         /* do not touch atomic flags, it needs atomic ops against the timer */
 154         rq->cpu = -1;
 155         INIT_HLIST_NODE(&rq->hash);
 156         RB_CLEAR_NODE(&rq->rb_node);
 157         rq->rq_disk = NULL;
 158         rq->part = NULL;
 159         rq->start_time = jiffies;
 160 #ifdef CONFIG_BLK_CGROUP
 161         rq->rl = NULL;
 162         set_start_time_ns(rq);
 163         rq->io_start_time_ns = 0;
 164 #endif
 165         rq->nr_phys_segments = 0;
 166 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 167         rq->nr_integrity_segments = 0;
 168 #endif
 169         rq->special = NULL;
 170         /* tag was already set */
 171         rq->errors = 0;
 172
 173         rq->cmd = rq->__cmd;
 174
 175         rq->extra_len = 0;
 176         rq->sense_len = 0;
 177         rq->resid_len = 0;
 178         rq->sense = NULL;
 179
 180         INIT_LIST_HEAD(&rq->timeout_list);
 181         rq->timeout = 0;
 182
 183         rq->end_io = NULL;
 184         rq->end_io_data = NULL;
 185         rq->next_rq = NULL;
 186
 187         ctx->rq_dispatched[rw_is_sync(op, op_flags)]++;
 188 }
 189
 190 static struct request *
 191 __blk_mq_alloc_request(struct blk_mq_alloc_data *data, int op, int op_flags)
 192 {
 193         struct request *rq;
 194         unsigned int tag;
 195
 196         tag = blk_mq_get_tag(data);
 197         if (tag != BLK_MQ_TAG_FAIL) {
 198                 rq = data->hctx->tags->rqs[tag];
 199
 200                 if (blk_mq_tag_busy(data->hctx)) {
 201                         rq->cmd_flags = REQ_MQ_INFLIGHT;
 202                         atomic_inc(&data->hctx->nr_active);
 203                 }
 204
 205                 rq->tag = tag;
 206                 blk_mq_rq_ctx_init(data->q, data->ctx, rq, op, op_flags);
 207                 return rq;
 208         }
 209
 210         return NULL;
 211 }
 212
 213 struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
 214                 unsigned int flags)
 215 {
 216         struct blk_mq_ctx *ctx;
 217         struct blk_mq_hw_ctx *hctx;
 218         struct request *rq;
 219         struct blk_mq_alloc_data alloc_data;
 220         int ret;
 221
 222         ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
 223         if (ret)
 224                 return ERR_PTR(ret);
 225
 226         ctx = blk_mq_get_ctx(q);
 227         hctx = blk_mq_map_queue(q, ctx->cpu);
 228         blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
 229         rq = __blk_mq_alloc_request(&alloc_data, rw, 0);
 230         blk_mq_put_ctx(ctx);
 231
 232         if (!rq) {
 233                 blk_queue_exit(q);
 234                 return ERR_PTR(-EWOULDBLOCK);
 235         }
 236
 237         rq->__data_len = 0;
 238         rq->__sector = (sector_t) -1;
 239         rq->bio = rq->biotail = NULL;
 240         return rq;
 241 }
 242 EXPORT_SYMBOL(blk_mq_alloc_request);
 243
 244 struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
 245                 unsigned int flags, unsigned int hctx_idx)
 246 {
 247         struct blk_mq_hw_ctx *hctx;
 248         struct blk_mq_ctx *ctx;
 249         struct request *rq;
 250         struct blk_mq_alloc_data alloc_data;
 251         int ret;
 252
 253         /*
 254          * If the tag allocator sleeps we could get an allocation for a
 255          * different hardware context.  No need to complicate the low level
 256          * allocator for this for the rare use case of a command tied to
 257          * a specific queue.
 258          */
 259         if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
 260                 return ERR_PTR(-EINVAL);
 261
 262         if (hctx_idx >= q->nr_hw_queues)
 263                 return ERR_PTR(-EIO);
 264
 265         ret = blk_queue_enter(q, true);
 266         if (ret)
 267                 return ERR_PTR(ret);
 268
 269         /*
 270          * Check if the hardware context is actually mapped to anything.
 271          * If not tell the caller that it should skip this queue.
 272          */
 273         hctx = q->queue_hw_ctx[hctx_idx];
 274         if (!blk_mq_hw_queue_mapped(hctx)) {
 275                 ret = -EXDEV;
 276                 goto out_queue_exit;
 277         }
 278         ctx = __blk_mq_get_ctx(q, cpumask_first(hctx->cpumask));
 279
 280         blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
 281         rq = __blk_mq_alloc_request(&alloc_data, rw, 0);
 282         if (!rq) {
 283                 ret = -EWOULDBLOCK;
 284                 goto out_queue_exit;
 285         }
 286
 287         return rq;
 288
 289 out_queue_exit:
 290         blk_queue_exit(q);
 291         return ERR_PTR(ret);
 292 }
 293 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
 294
 295 static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
 296                                   struct blk_mq_ctx *ctx, struct request *rq)
 297 {
 298         const int tag = rq->tag;
 299         struct request_queue *q = rq->q;
 300
 301         if (rq->cmd_flags & REQ_MQ_INFLIGHT)
 302                 atomic_dec(&hctx->nr_active);
 303         rq->cmd_flags = 0;
 304
 305         clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 306         blk_mq_put_tag(hctx, ctx, tag);
 307         blk_queue_exit(q);
 308 }
 309
 310 void blk_mq_free_hctx_request(struct blk_mq_hw_ctx *hctx, struct request *rq)
 311 {
 312         struct blk_mq_ctx *ctx = rq->mq_ctx;
 313
 314         ctx->rq_completed[rq_is_sync(rq)]++;
 315         __blk_mq_free_request(hctx, ctx, rq);
 316
 317 }
 318 EXPORT_SYMBOL_GPL(blk_mq_free_hctx_request);
 319
 320 void blk_mq_free_request(struct request *rq)
 321 {
 322         blk_mq_free_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
 323 }
 324 EXPORT_SYMBOL_GPL(blk_mq_free_request);
 325
 326 inline void __blk_mq_end_request(struct request *rq, int error)
 327 {
 328         blk_account_io_done(rq);
 329
 330         if (rq->end_io) {
 331                 rq->end_io(rq, error);
 332         } else {
 333                 if (unlikely(blk_bidi_rq(rq)))
 334                         blk_mq_free_request(rq->next_rq);
 335                 blk_mq_free_request(rq);
 336         }
 337 }
 338 EXPORT_SYMBOL(__blk_mq_end_request);
 339
 340 void blk_mq_end_request(struct request *rq, int error)
 341 {
 342         if (blk_update_request(rq, error, blk_rq_bytes(rq)))
 343                 BUG();
 344         __blk_mq_end_request(rq, error);
 345 }
 346 EXPORT_SYMBOL(blk_mq_end_request);
 347
 348 static void __blk_mq_complete_request_remote(void *data)
 349 {
 350         struct request *rq = data;
 351
 352         rq->q->softirq_done_fn(rq);
 353 }
 354
 355 static void blk_mq_ipi_complete_request(struct request *rq)
 356 {
 357         struct blk_mq_ctx *ctx = rq->mq_ctx;
 358         bool shared = false;
 359         int cpu;
 360
 361         if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
 362                 rq->q->softirq_done_fn(rq);
 363                 return;
 364         }
 365
 366         cpu = get_cpu();
 367         if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
 368                 shared = cpus_share_cache(cpu, ctx->cpu);
 369
 370         if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
 371                 rq->csd.func = __blk_mq_complete_request_remote;
 372                 rq->csd.info = rq;
 373                 rq->csd.flags = 0;
 374                 smp_call_function_single_async(ctx->cpu, &rq->csd);
 375         } else {
 376                 rq->q->softirq_done_fn(rq);
 377         }
 378         put_cpu();
 379 }
 380
 381 static void __blk_mq_complete_request(struct request *rq)
 382 {
 383         struct request_queue *q = rq->q;
 384
 385         if (!q->softirq_done_fn)
 386                 blk_mq_end_request(rq, rq->errors);
 387         else
 388                 blk_mq_ipi_complete_request(rq);
 389 }
 390
 391 /**
 392  * blk_mq_complete_request - end I/O on a request
 393  * @rq:         the request being processed
 394  *
 395  * Description:
 396  *      Ends all I/O on a request. It does not handle partial completions.
 397  *      The actual completion happens out-of-order, through a IPI handler.
 398  **/
 399 void blk_mq_complete_request(struct request *rq, int error)
 400 {
 401         struct request_queue *q = rq->q;
 402
 403         if (unlikely(blk_should_fake_timeout(q)))
 404                 return;
 405         if (!blk_mark_rq_complete(rq)) {
 406                 rq->errors = error;
 407                 __blk_mq_complete_request(rq);
 408         }
 409 }
 410 EXPORT_SYMBOL(blk_mq_complete_request);
 411
 412 int blk_mq_request_started(struct request *rq)
 413 {
 414         return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 415 }
 416 EXPORT_SYMBOL_GPL(blk_mq_request_started);
 417
 418 void blk_mq_start_request(struct request *rq)
 419 {
 420         struct request_queue *q = rq->q;
 421
 422         trace_block_rq_issue(q, rq);
 423
 424         rq->resid_len = blk_rq_bytes(rq);
 425         if (unlikely(blk_bidi_rq(rq)))
 426                 rq->next_rq->resid_len = blk_rq_bytes(rq->next_rq);
 427
 428         blk_add_timer(rq);
 429
 430         /*
 431          * Ensure that ->deadline is visible before set the started
 432          * flag and clear the completed flag.
 433          */
 434         smp_mb__before_atomic();
 435
 436         /*
 437          * Mark us as started and clear complete. Complete might have been
 438          * set if requeue raced with timeout, which then marked it as
 439          * complete. So be sure to clear complete again when we start
 440          * the request, otherwise we'll ignore the completion event.
 441          */
 442         if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
 443                 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 444         if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
 445                 clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
 446
 447         if (q->dma_drain_size && blk_rq_bytes(rq)) {
 448                 /*
 449                  * Make sure space for the drain appears.  We know we can do
 450                  * this because max_hw_segments has been adjusted to be one
 451                  * fewer than the device can handle.
 452                  */
 453                 rq->nr_phys_segments++;
 454         }
 455 }
 456 EXPORT_SYMBOL(blk_mq_start_request);
 457
 458 static void __blk_mq_requeue_request(struct request *rq)
 459 {
 460         struct request_queue *q = rq->q;
 461
 462         trace_block_rq_requeue(q, rq);
 463
 464         if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
 465                 if (q->dma_drain_size && blk_rq_bytes(rq))
 466                         rq->nr_phys_segments--;
 467         }
 468 }
 469
 470 void blk_mq_requeue_request(struct request *rq)
 471 {
 472         __blk_mq_requeue_request(rq);
 473
 474         BUG_ON(blk_queued_rq(rq));
 475         blk_mq_add_to_requeue_list(rq, true);
 476 }
 477 EXPORT_SYMBOL(blk_mq_requeue_request);
 478
 479 static void blk_mq_requeue_work(struct work_struct *work)
 480 {
 481         struct request_queue *q =
 482                 container_of(work, struct request_queue, requeue_work.work);
 483         LIST_HEAD(rq_list);
 484         struct request *rq, *next;
 485         unsigned long flags;
 486
 487         spin_lock_irqsave(&q->requeue_lock, flags);
 488         list_splice_init(&q->requeue_list, &rq_list);
 489         spin_unlock_irqrestore(&q->requeue_lock, flags);
 490
 491         list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
 492                 if (!(rq->cmd_flags & REQ_SOFTBARRIER))
 493                         continue;
 494
 495                 rq->cmd_flags &= ~REQ_SOFTBARRIER;
 496                 list_del_init(&rq->queuelist);
 497                 blk_mq_insert_request(rq, true, false, false);
 498         }
 499
 500         while (!list_empty(&rq_list)) {
 501                 rq = list_entry(rq_list.next, struct request, queuelist);
 502                 list_del_init(&rq->queuelist);
 503                 blk_mq_insert_request(rq, false, false, false);
 504         }
 505
 506         /*
 507          * Use the start variant of queue running here, so that running
 508          * the requeue work will kick stopped queues.
 509          */
 510         blk_mq_start_hw_queues(q);
 511 }
 512
 513 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head)
 514 {
 515         struct request_queue *q = rq->q;
 516         unsigned long flags;
 517
 518         /*
 519          * We abuse this flag that is otherwise used by the I/O scheduler to
 520          * request head insertation from the workqueue.
 521          */
 522         BUG_ON(rq->cmd_flags & REQ_SOFTBARRIER);
 523
 524         spin_lock_irqsave(&q->requeue_lock, flags);
 525         if (at_head) {
 526                 rq->cmd_flags |= REQ_SOFTBARRIER;
 527                 list_add(&rq->queuelist, &q->requeue_list);
 528         } else {
 529                 list_add_tail(&rq->queuelist, &q->requeue_list);
 530         }
 531         spin_unlock_irqrestore(&q->requeue_lock, flags);
 532 }
 533 EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
 534
 535 void blk_mq_cancel_requeue_work(struct request_queue *q)
 536 {
 537         cancel_delayed_work_sync(&q->requeue_work);
 538 }
 539 EXPORT_SYMBOL_GPL(blk_mq_cancel_requeue_work);
 540
 541 void blk_mq_kick_requeue_list(struct request_queue *q)
 542 {
 543         kblockd_schedule_delayed_work(&q->requeue_work, 0);
 544 }
 545 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
 546
 547 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
 548                                     unsigned long msecs)
 549 {
 550         kblockd_schedule_delayed_work(&q->requeue_work,
 551                                       msecs_to_jiffies(msecs));
 552 }
 553 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
 554
 555 void blk_mq_abort_requeue_list(struct request_queue *q)
 556 {
 557         unsigned long flags;
 558         LIST_HEAD(rq_list);
 559
 560         spin_lock_irqsave(&q->requeue_lock, flags);
 561         list_splice_init(&q->requeue_list, &rq_list);
 562         spin_unlock_irqrestore(&q->requeue_lock, flags);
 563
 564         while (!list_empty(&rq_list)) {
 565                 struct request *rq;
 566
 567                 rq = list_first_entry(&rq_list, struct request, queuelist);
 568                 list_del_init(&rq->queuelist);
 569                 rq->errors = -EIO;
 570                 blk_mq_end_request(rq, rq->errors);
 571         }
 572 }
 573 EXPORT_SYMBOL(blk_mq_abort_requeue_list);
 574
 575 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
 576 {
 577         if (tag < tags->nr_tags) {
 578                 prefetch(tags->rqs[tag]);
 579                 return tags->rqs[tag];
 580         }
 581
 582         return NULL;
 583 }
 584 EXPORT_SYMBOL(blk_mq_tag_to_rq);
 585
 586 struct blk_mq_timeout_data {
 587         unsigned long next;
 588         unsigned int next_set;
 589 };
 590
 591 void blk_mq_rq_timed_out(struct request *req, bool reserved)
 592 {
 593         struct blk_mq_ops *ops = req->q->mq_ops;
 594         enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
 595
 596         /*
 597          * We know that complete is set at this point. If STARTED isn't set
 598          * anymore, then the request isn't active and the "timeout" should
 599          * just be ignored. This can happen due to the bitflag ordering.
 600          * Timeout first checks if STARTED is set, and if it is, assumes
 601          * the request is active. But if we race with completion, then
 602          * we both flags will get cleared. So check here again, and ignore
 603          * a timeout event with a request that isn't active.
 604          */
 605         if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
 606                 return;
 607
 608         if (ops->timeout)
 609                 ret = ops->timeout(req, reserved);
 610
 611         switch (ret) {
 612         case BLK_EH_HANDLED:
 613                 __blk_mq_complete_request(req);
 614                 break;
 615         case BLK_EH_RESET_TIMER:
 616                 blk_add_timer(req);
 617                 blk_clear_rq_complete(req);
 618                 break;
 619         case BLK_EH_NOT_HANDLED:
 620                 break;
 621         default:
 622                 printk(KERN_ERR "block: bad eh return: %d\n", ret);
 623                 break;
 624         }
 625 }
 626
 627 static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
 628                 struct request *rq, void *priv, bool reserved)
 629 {
 630         struct blk_mq_timeout_data *data = priv;
 631
 632         if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
 633                 /*
 634                  * If a request wasn't started before the queue was
 635                  * marked dying, kill it here or it'll go unnoticed.
 636                  */
 637                 if (unlikely(blk_queue_dying(rq->q))) {
 638                         rq->errors = -EIO;
 639                         blk_mq_end_request(rq, rq->errors);
 640                 }
 641                 return;
 642         }
 643
 644         if (time_after_eq(jiffies, rq->deadline)) {
 645                 if (!blk_mark_rq_complete(rq))
 646                         blk_mq_rq_timed_out(rq, reserved);
 647         } else if (!data->next_set || time_after(data->next, rq->deadline)) {
 648                 data->next = rq->deadline;
 649                 data->next_set = 1;
 650         }
 651 }
 652
 653 static void blk_mq_timeout_work(struct work_struct *work)
 654 {
 655         struct request_queue *q =
 656                 container_of(work, struct request_queue, timeout_work);
 657         struct blk_mq_timeout_data data = {
 658                 .next           = 0,
 659                 .next_set       = 0,
 660         };
 661         int i;
 662
 663         /* A deadlock might occur if a request is stuck requiring a
 664          * timeout at the same time a queue freeze is waiting
 665          * completion, since the timeout code would not be able to
 666          * acquire the queue reference here.
 667          *
 668          * That's why we don't use blk_queue_enter here; instead, we use
 669          * percpu_ref_tryget directly, because we need to be able to
 670          * obtain a reference even in the short window between the queue
 671          * starting to freeze, by dropping the first reference in
 672          * blk_mq_freeze_queue_start, and the moment the last request is
 673          * consumed, marked by the instant q_usage_counter reaches
 674          * zero.
 675          */
 676         if (!percpu_ref_tryget(&q->q_usage_counter))
 677                 return;
 678
 679         blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
 680
 681         if (data.next_set) {
 682                 data.next = blk_rq_timeout(round_jiffies_up(data.next));
 683                 mod_timer(&q->timeout, data.next);
 684         } else {
 685                 struct blk_mq_hw_ctx *hctx;
 686
 687                 queue_for_each_hw_ctx(q, hctx, i) {
 688                         /* the hctx may be unmapped, so check it here */
 689                         if (blk_mq_hw_queue_mapped(hctx))
 690                                 blk_mq_tag_idle(hctx);
 691                 }
 692         }
 693         blk_queue_exit(q);
 694 }
 695
 696 /*
 697  * Reverse check our software queue for entries that we could potentially
 698  * merge with. Currently includes a hand-wavy stop count of 8, to not spend
 699  * too much time checking for merges.
 700  */
 701 static bool blk_mq_attempt_merge(struct request_queue *q,
 702                                  struct blk_mq_ctx *ctx, struct bio *bio)
 703 {
 704         struct request *rq;
 705         int checked = 8;
 706
 707         list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
 708                 int el_ret;
 709
 710                 if (!checked--)
 711                         break;
 712
 713                 if (!blk_rq_merge_ok(rq, bio))
 714                         continue;
 715
 716                 el_ret = blk_try_merge(rq, bio);
 717                 if (el_ret == ELEVATOR_BACK_MERGE) {
 718                         if (bio_attempt_back_merge(q, rq, bio)) {
 719                                 ctx->rq_merged++;
 720                                 return true;
 721                         }
 722                         break;
 723                 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
 724                         if (bio_attempt_front_merge(q, rq, bio)) {
 725                                 ctx->rq_merged++;
 726                                 return true;
 727                         }
 728                         break;
 729                 }
 730         }
 731
 732         return false;
 733 }
 734
 735 struct flush_busy_ctx_data {
 736         struct blk_mq_hw_ctx *hctx;
 737         struct list_head *list;
 738 };
 739
 740 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
 741 {
 742         struct flush_busy_ctx_data *flush_data = data;
 743         struct blk_mq_hw_ctx *hctx = flush_data->hctx;
 744         struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
 745
 746         sbitmap_clear_bit(sb, bitnr);
 747         spin_lock(&ctx->lock);
 748         list_splice_tail_init(&ctx->rq_list, flush_data->list);
 749         spin_unlock(&ctx->lock);
 750         return true;
 751 }
 752
 753 /*
 754  * Process software queues that have been marked busy, splicing them
 755  * to the for-dispatch
 756  */
 757 static void flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
 758 {
 759         struct flush_busy_ctx_data data = {
 760                 .hctx = hctx,
 761                 .list = list,
 762         };
 763
 764         sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
 765 }
 766
 767 static inline unsigned int queued_to_index(unsigned int queued)
 768 {
 769         if (!queued)
 770                 return 0;
 771
 772         return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
 773 }
 774
 775 /*
 776  * Run this hardware queue, pulling any software queues mapped to it in.
 777  * Note that this function currently has various problems around ordering
 778  * of IO. In particular, we'd like FIFO behaviour on handling existing
 779  * items on the hctx->dispatch list. Ignore that for now.
 780  */
 781 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
 782 {
 783         struct request_queue *q = hctx->queue;
 784         struct request *rq;
 785         LIST_HEAD(rq_list);
 786         LIST_HEAD(driver_list);
 787         struct list_head *dptr;
 788         int queued;
 789
 790         if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
 791                 return;
 792
 793         WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
 794                 cpu_online(hctx->next_cpu));
 795
 796         hctx->run++;
 797
 798         /*
 799          * Touch any software queue that has pending entries.
 800          */
 801         flush_busy_ctxs(hctx, &rq_list);
 802
 803         /*
 804          * If we have previous entries on our dispatch list, grab them
 805          * and stuff them at the front for more fair dispatch.
 806          */
 807         if (!list_empty_careful(&hctx->dispatch)) {
 808                 spin_lock(&hctx->lock);
 809                 if (!list_empty(&hctx->dispatch))
 810                         list_splice_init(&hctx->dispatch, &rq_list);
 811                 spin_unlock(&hctx->lock);
 812         }
 813
 814         /*
 815          * Start off with dptr being NULL, so we start the first request
 816          * immediately, even if we have more pending.
 817          */
 818         dptr = NULL;
 819
 820         /*
 821          * Now process all the entries, sending them to the driver.
 822          */
 823         queued = 0;
 824         while (!list_empty(&rq_list)) {
 825                 struct blk_mq_queue_data bd;
 826                 int ret;
 827
 828                 rq = list_first_entry(&rq_list, struct request, queuelist);
 829                 list_del_init(&rq->queuelist);
 830
 831                 bd.rq = rq;
 832                 bd.list = dptr;
 833                 bd.last = list_empty(&rq_list);
 834
 835                 ret = q->mq_ops->queue_rq(hctx, &bd);
 836                 switch (ret) {
 837                 case BLK_MQ_RQ_QUEUE_OK:
 838                         queued++;
 839                         break;
 840                 case BLK_MQ_RQ_QUEUE_BUSY:
 841                         list_add(&rq->queuelist, &rq_list);
 842                         __blk_mq_requeue_request(rq);
 843                         break;
 844                 default:
 845                         pr_err("blk-mq: bad return on queue: %d\n", ret);
 846                 case BLK_MQ_RQ_QUEUE_ERROR:
 847                         rq->errors = -EIO;
 848                         blk_mq_end_request(rq, rq->errors);
 849                         break;
 850                 }
 851
 852                 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
 853                         break;
 854
 855                 /*
 856                  * We've done the first request. If we have more than 1
 857                  * left in the list, set dptr to defer issue.
 858                  */
 859                 if (!dptr && rq_list.next != rq_list.prev)
 860                         dptr = &driver_list;
 861         }
 862
 863         hctx->dispatched[queued_to_index(queued)]++;
 864
 865         /*
 866          * Any items that need requeuing? Stuff them into hctx->dispatch,
 867          * that is where we will continue on next queue run.
 868          */
 869         if (!list_empty(&rq_list)) {
 870                 spin_lock(&hctx->lock);
 871                 list_splice(&rq_list, &hctx->dispatch);
 872                 spin_unlock(&hctx->lock);
 873                 /*
 874                  * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
 875                  * it's possible the queue is stopped and restarted again
 876                  * before this. Queue restart will dispatch requests. And since
 877                  * requests in rq_list aren't added into hctx->dispatch yet,
 878                  * the requests in rq_list might get lost.
 879                  *
 880                  * blk_mq_run_hw_queue() already checks the STOPPED bit
 881                  **/
 882                 blk_mq_run_hw_queue(hctx, true);
 883         }
 884 }
 885
 886 /*
 887  * It'd be great if the workqueue API had a way to pass
 888  * in a mask and had some smarts for more clever placement.
 889  * For now we just round-robin here, switching for every
 890  * BLK_MQ_CPU_WORK_BATCH queued items.
 891  */
 892 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
 893 {
 894         if (hctx->queue->nr_hw_queues == 1)
 895                 return WORK_CPU_UNBOUND;
 896
 897         if (--hctx->next_cpu_batch <= 0) {
 898                 int cpu = hctx->next_cpu, next_cpu;
 899
 900                 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
 901                 if (next_cpu >= nr_cpu_ids)
 902                         next_cpu = cpumask_first(hctx->cpumask);
 903
 904                 hctx->next_cpu = next_cpu;
 905                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
 906
 907                 return cpu;
 908         }
 909
 910         return hctx->next_cpu;
 911 }
 912
 913 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
 914 {
 915         if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state) ||
 916             !blk_mq_hw_queue_mapped(hctx)))
 917                 return;
 918
 919         if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
 920                 int cpu = get_cpu();
 921                 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
 922                         __blk_mq_run_hw_queue(hctx);
 923                         put_cpu();
 924                         return;
 925                 }
 926
 927                 put_cpu();
 928         }
 929
 930         kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work);
 931 }
 932
 933 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
 934 {
 935         struct blk_mq_hw_ctx *hctx;
 936         int i;
 937
 938         queue_for_each_hw_ctx(q, hctx, i) {
 939                 if ((!blk_mq_hctx_has_pending(hctx) &&
 940                     list_empty_careful(&hctx->dispatch)) ||
 941                     test_bit(BLK_MQ_S_STOPPED, &hctx->state))
 942                         continue;
 943
 944                 blk_mq_run_hw_queue(hctx, async);
 945         }
 946 }
 947 EXPORT_SYMBOL(blk_mq_run_hw_queues);
 948
 949 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
 950 {
 951         cancel_work(&hctx->run_work);
 952         cancel_delayed_work(&hctx->delay_work);
 953         set_bit(BLK_MQ_S_STOPPED, &hctx->state);
 954 }
 955 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
 956
 957 void blk_mq_stop_hw_queues(struct request_queue *q)
 958 {
 959         struct blk_mq_hw_ctx *hctx;
 960         int i;
 961
 962         queue_for_each_hw_ctx(q, hctx, i)
 963                 blk_mq_stop_hw_queue(hctx);
 964 }
 965 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
 966
 967 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
 968 {
 969         clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
 970
 971         blk_mq_run_hw_queue(hctx, false);
 972 }
 973 EXPORT_SYMBOL(blk_mq_start_hw_queue);
 974
 975 void blk_mq_start_hw_queues(struct request_queue *q)
 976 {
 977         struct blk_mq_hw_ctx *hctx;
 978         int i;
 979
 980         queue_for_each_hw_ctx(q, hctx, i)
 981                 blk_mq_start_hw_queue(hctx);
 982 }
 983 EXPORT_SYMBOL(blk_mq_start_hw_queues);
 984
 985 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
 986 {
 987         struct blk_mq_hw_ctx *hctx;
 988         int i;
 989
 990         queue_for_each_hw_ctx(q, hctx, i) {
 991                 if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
 992                         continue;
 993
 994                 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
 995                 blk_mq_run_hw_queue(hctx, async);
 996         }
 997 }
 998 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
 999
1000 static void blk_mq_run_work_fn(struct work_struct *work)
1001 {
1002         struct blk_mq_hw_ctx *hctx;
1003
1004         hctx = container_of(work, struct blk_mq_hw_ctx, run_work);
1005
1006         __blk_mq_run_hw_queue(hctx);
1007 }
1008
1009 static void blk_mq_delay_work_fn(struct work_struct *work)
1010 {
1011         struct blk_mq_hw_ctx *hctx;
1012
1013         hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
1014
1015         if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
1016                 __blk_mq_run_hw_queue(hctx);
1017 }
1018
1019 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1020 {
1021         if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
1022                 return;
1023
1024         kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1025                         &hctx->delay_work, msecs_to_jiffies(msecs));
1026 }
1027 EXPORT_SYMBOL(blk_mq_delay_queue);
1028
1029 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1030                                             struct request *rq,
1031                                             bool at_head)
1032 {
1033         struct blk_mq_ctx *ctx = rq->mq_ctx;
1034
1035         trace_block_rq_insert(hctx->queue, rq);
1036
1037         if (at_head)
1038                 list_add(&rq->queuelist, &ctx->rq_list);
1039         else
1040                 list_add_tail(&rq->queuelist, &ctx->rq_list);
1041 }
1042
1043 static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
1044                                     struct request *rq, bool at_head)
1045 {
1046         struct blk_mq_ctx *ctx = rq->mq_ctx;
1047
1048         __blk_mq_insert_req_list(hctx, rq, at_head);
1049         blk_mq_hctx_mark_pending(hctx, ctx);
1050 }
1051
1052 void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
1053                            bool async)
1054 {
1055         struct blk_mq_ctx *ctx = rq->mq_ctx;
1056         struct request_queue *q = rq->q;
1057         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
1058
1059         spin_lock(&ctx->lock);
1060         __blk_mq_insert_request(hctx, rq, at_head);
1061         spin_unlock(&ctx->lock);
1062
1063         if (run_queue)
1064                 blk_mq_run_hw_queue(hctx, async);
1065 }
1066
1067 static void blk_mq_insert_requests(struct request_queue *q,
1068                                      struct blk_mq_ctx *ctx,
1069                                      struct list_head *list,
1070                                      int depth,
1071                                      bool from_schedule)
1072
1073 {
1074         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
1075
1076         trace_block_unplug(q, depth, !from_schedule);
1077
1078         /*
1079          * preemption doesn't flush plug list, so it's possible ctx->cpu is
1080          * offline now
1081          */
1082         spin_lock(&ctx->lock);
1083         while (!list_empty(list)) {
1084                 struct request *rq;
1085
1086                 rq = list_first_entry(list, struct request, queuelist);
1087                 BUG_ON(rq->mq_ctx != ctx);
1088                 list_del_init(&rq->queuelist);
1089                 __blk_mq_insert_req_list(hctx, rq, false);
1090         }
1091         blk_mq_hctx_mark_pending(hctx, ctx);
1092         spin_unlock(&ctx->lock);
1093
1094         blk_mq_run_hw_queue(hctx, from_schedule);
1095 }
1096
1097 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1098 {
1099         struct request *rqa = container_of(a, struct request, queuelist);
1100         struct request *rqb = container_of(b, struct request, queuelist);
1101
1102         return !(rqa->mq_ctx < rqb->mq_ctx ||
1103                  (rqa->mq_ctx == rqb->mq_ctx &&
1104                   blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1105 }
1106
1107 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1108 {
1109         struct blk_mq_ctx *this_ctx;
1110         struct request_queue *this_q;
1111         struct request *rq;
1112         LIST_HEAD(list);
1113         LIST_HEAD(ctx_list);
1114         unsigned int depth;
1115
1116         list_splice_init(&plug->mq_list, &list);
1117
1118         list_sort(NULL, &list, plug_ctx_cmp);
1119
1120         this_q = NULL;
1121         this_ctx = NULL;
1122         depth = 0;
1123
1124         while (!list_empty(&list)) {
1125                 rq = list_entry_rq(list.next);
1126                 list_del_init(&rq->queuelist);
1127                 BUG_ON(!rq->q);
1128                 if (rq->mq_ctx != this_ctx) {
1129                         if (this_ctx) {
1130                                 blk_mq_insert_requests(this_q, this_ctx,
1131                                                         &ctx_list, depth,
1132                                                         from_schedule);
1133                         }
1134
1135                         this_ctx = rq->mq_ctx;
1136                         this_q = rq->q;
1137                         depth = 0;
1138                 }
1139
1140                 depth++;
1141                 list_add_tail(&rq->queuelist, &ctx_list);
1142         }
1143
1144         /*
1145          * If 'this_ctx' is set, we know we have entries to complete
1146          * on 'ctx_list'. Do those.
1147          */
1148         if (this_ctx) {
1149                 blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
1150                                        from_schedule);
1151         }
1152 }
1153
1154 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1155 {
1156         init_request_from_bio(rq, bio);
1157
1158         blk_account_io_start(rq, 1);
1159 }
1160
1161 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
1162 {
1163         return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
1164                 !blk_queue_nomerges(hctx->queue);
1165 }
1166
1167 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
1168                                          struct blk_mq_ctx *ctx,
1169                                          struct request *rq, struct bio *bio)
1170 {
1171         if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
1172                 blk_mq_bio_to_request(rq, bio);
1173                 spin_lock(&ctx->lock);
1174 insert_rq:
1175                 __blk_mq_insert_request(hctx, rq, false);
1176                 spin_unlock(&ctx->lock);
1177                 return false;
1178         } else {
1179                 struct request_queue *q = hctx->queue;
1180
1181                 spin_lock(&ctx->lock);
1182                 if (!blk_mq_attempt_merge(q, ctx, bio)) {
1183                         blk_mq_bio_to_request(rq, bio);
1184                         goto insert_rq;
1185                 }
1186
1187                 spin_unlock(&ctx->lock);
1188                 __blk_mq_free_request(hctx, ctx, rq);
1189                 return true;
1190         }
1191 }
1192
1193 struct blk_map_ctx {
1194         struct blk_mq_hw_ctx *hctx;
1195         struct blk_mq_ctx *ctx;
1196 };
1197
1198 static struct request *blk_mq_map_request(struct request_queue *q,
1199                                           struct bio *bio,
1200                                           struct blk_map_ctx *data)
1201 {
1202         struct blk_mq_hw_ctx *hctx;
1203         struct blk_mq_ctx *ctx;
1204         struct request *rq;
1205         int op = bio_data_dir(bio);
1206         int op_flags = 0;
1207         struct blk_mq_alloc_data alloc_data;
1208
1209         blk_queue_enter_live(q);
1210         ctx = blk_mq_get_ctx(q);
1211         hctx = blk_mq_map_queue(q, ctx->cpu);
1212
1213         if (rw_is_sync(bio_op(bio), bio->bi_opf))
1214                 op_flags |= REQ_SYNC;
1215
1216         trace_block_getrq(q, bio, op);
1217         blk_mq_set_alloc_data(&alloc_data, q, 0, ctx, hctx);
1218         rq = __blk_mq_alloc_request(&alloc_data, op, op_flags);
1219
1220         data->hctx = alloc_data.hctx;
1221         data->ctx = alloc_data.ctx;
1222         data->hctx->queued++;
1223         return rq;
1224 }
1225
1226 static int blk_mq_direct_issue_request(struct request *rq, blk_qc_t *cookie)
1227 {
1228         int ret;
1229         struct request_queue *q = rq->q;
1230         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
1231         struct blk_mq_queue_data bd = {
1232                 .rq = rq,
1233                 .list = NULL,
1234                 .last = 1
1235         };
1236         blk_qc_t new_cookie = blk_tag_to_qc_t(rq->tag, hctx->queue_num);
1237
1238         /*
1239          * For OK queue, we are done. For error, kill it. Any other
1240          * error (busy), just add it to our list as we previously
1241          * would have done
1242          */
1243         ret = q->mq_ops->queue_rq(hctx, &bd);
1244         if (ret == BLK_MQ_RQ_QUEUE_OK) {
1245                 *cookie = new_cookie;
1246                 return 0;
1247         }
1248
1249         __blk_mq_requeue_request(rq);
1250
1251         if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
1252                 *cookie = BLK_QC_T_NONE;
1253                 rq->errors = -EIO;
1254                 blk_mq_end_request(rq, rq->errors);
1255                 return 0;
1256         }
1257
1258         return -1;
1259 }
1260
1261 /*
1262  * Multiple hardware queue variant. This will not use per-process plugs,
1263  * but will attempt to bypass the hctx queueing if we can go straight to
1264  * hardware for SYNC IO.
1265  */
1266 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1267 {
1268         const int is_sync = rw_is_sync(bio_op(bio), bio->bi_opf);
1269         const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
1270         struct blk_map_ctx data;
1271         struct request *rq;
1272         unsigned int request_count = 0;
1273         struct blk_plug *plug;
1274         struct request *same_queue_rq = NULL;
1275         blk_qc_t cookie;
1276
1277         blk_queue_bounce(q, &bio);
1278
1279         if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1280                 bio_io_error(bio);
1281                 return BLK_QC_T_NONE;
1282         }
1283
1284         blk_queue_split(q, &bio, q->bio_split);
1285
1286         if (!is_flush_fua && !blk_queue_nomerges(q) &&
1287             blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1288                 return BLK_QC_T_NONE;
1289
1290         rq = blk_mq_map_request(q, bio, &data);
1291         if (unlikely(!rq))
1292                 return BLK_QC_T_NONE;
1293
1294         cookie = blk_tag_to_qc_t(rq->tag, data.hctx->queue_num);
1295
1296         if (unlikely(is_flush_fua)) {
1297                 blk_mq_bio_to_request(rq, bio);
1298                 blk_insert_flush(rq);
1299                 goto run_queue;
1300         }
1301
1302         plug = current->plug;
1303         /*
1304          * If the driver supports defer issued based on 'last', then
1305          * queue it up like normal since we can potentially save some
1306          * CPU this way.
1307          */
1308         if (((plug && !blk_queue_nomerges(q)) || is_sync) &&
1309             !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
1310                 struct request *old_rq = NULL;
1311
1312                 blk_mq_bio_to_request(rq, bio);
1313
1314                 /*
1315                  * We do limited pluging. If the bio can be merged, do that.
1316                  * Otherwise the existing request in the plug list will be
1317                  * issued. So the plug list will have one request at most
1318                  */
1319                 if (plug) {
1320                         /*
1321                          * The plug list might get flushed before this. If that
1322                          * happens, same_queue_rq is invalid and plug list is
1323                          * empty
1324                          */
1325                         if (same_queue_rq && !list_empty(&plug->mq_list)) {
1326                                 old_rq = same_queue_rq;
1327                                 list_del_init(&old_rq->queuelist);
1328                         }
1329                         list_add_tail(&rq->queuelist, &plug->mq_list);
1330                 } else /* is_sync */
1331                         old_rq = rq;
1332                 blk_mq_put_ctx(data.ctx);
1333                 if (!old_rq)
1334                         goto done;
1335                 if (!blk_mq_direct_issue_request(old_rq, &cookie))
1336                         goto done;
1337                 blk_mq_insert_request(old_rq, false, true, true);
1338                 goto done;
1339         }
1340
1341         if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1342                 /*
1343                  * For a SYNC request, send it to the hardware immediately. For
1344                  * an ASYNC request, just ensure that we run it later on. The
1345                  * latter allows for merging opportunities and more efficient
1346                  * dispatching.
1347                  */
1348 run_queue:
1349                 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1350         }
1351         blk_mq_put_ctx(data.ctx);
1352 done:
1353         return cookie;
1354 }
1355
1356 /*
1357  * Single hardware queue variant. This will attempt to use any per-process
1358  * plug for merging and IO deferral.
1359  */
1360 static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
1361 {
1362         const int is_sync = rw_is_sync(bio_op(bio), bio->bi_opf);
1363         const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
1364         struct blk_plug *plug;
1365         unsigned int request_count = 0;
1366         struct blk_map_ctx data;
1367         struct request *rq;
1368         blk_qc_t cookie;
1369
1370         blk_queue_bounce(q, &bio);
1371
1372         if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1373                 bio_io_error(bio);
1374                 return BLK_QC_T_NONE;
1375         }
1376
1377         blk_queue_split(q, &bio, q->bio_split);
1378
1379         if (!is_flush_fua && !blk_queue_nomerges(q)) {
1380                 if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
1381                         return BLK_QC_T_NONE;
1382         } else
1383                 request_count = blk_plug_queued_count(q);
1384
1385         rq = blk_mq_map_request(q, bio, &data);
1386         if (unlikely(!rq))
1387                 return BLK_QC_T_NONE;
1388
1389         cookie = blk_tag_to_qc_t(rq->tag, data.hctx->queue_num);
1390
1391         if (unlikely(is_flush_fua)) {
1392                 blk_mq_bio_to_request(rq, bio);
1393                 blk_insert_flush(rq);
1394                 goto run_queue;
1395         }
1396
1397         /*
1398          * A task plug currently exists. Since this is completely lockless,
1399          * utilize that to temporarily store requests until the task is
1400          * either done or scheduled away.
1401          */
1402         plug = current->plug;
1403         if (plug) {
1404                 blk_mq_bio_to_request(rq, bio);
1405                 if (!request_count)
1406                         trace_block_plug(q);
1407
1408                 blk_mq_put_ctx(data.ctx);
1409
1410                 if (request_count >= BLK_MAX_REQUEST_COUNT) {
1411                         blk_flush_plug_list(plug, false);
1412                         trace_block_plug(q);
1413                 }
1414
1415                 list_add_tail(&rq->queuelist, &plug->mq_list);
1416                 return cookie;
1417         }
1418
1419         if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1420                 /*
1421                  * For a SYNC request, send it to the hardware immediately. For
1422                  * an ASYNC request, just ensure that we run it later on. The
1423                  * latter allows for merging opportunities and more efficient
1424                  * dispatching.
1425                  */
1426 run_queue:
1427                 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1428         }
1429
1430         blk_mq_put_ctx(data.ctx);
1431         return cookie;
1432 }
1433
1434 static void blk_mq_free_rq_map(struct blk_mq_tag_set *set,
1435                 struct blk_mq_tags *tags, unsigned int hctx_idx)
1436 {
1437         struct page *page;
1438
1439         if (tags->rqs && set->ops->exit_request) {
1440                 int i;
1441
1442                 for (i = 0; i < tags->nr_tags; i++) {
1443                         if (!tags->rqs[i])
1444                                 continue;
1445                         set->ops->exit_request(set->driver_data, tags->rqs[i],
1446                                                 hctx_idx, i);
1447                         tags->rqs[i] = NULL;
1448                 }
1449         }
1450
1451         while (!list_empty(&tags->page_list)) {
1452                 page = list_first_entry(&tags->page_list, struct page, lru);
1453                 list_del_init(&page->lru);
1454                 /*
1455                  * Remove kmemleak object previously allocated in
1456                  * blk_mq_init_rq_map().
1457                  */
1458                 kmemleak_free(page_address(page));
1459                 __free_pages(page, page->private);
1460         }
1461
1462         kfree(tags->rqs);
1463
1464         blk_mq_free_tags(tags);
1465 }
1466
1467 static size_t order_to_size(unsigned int order)
1468 {
1469         return (size_t)PAGE_SIZE << order;
1470 }
1471
1472 static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
1473                 unsigned int hctx_idx)
1474 {
1475         struct blk_mq_tags *tags;
1476         unsigned int i, j, entries_per_page, max_order = 4;
1477         size_t rq_size, left;
1478
1479         tags = blk_mq_init_tags(set->queue_depth, set->reserved_tags,
1480                                 set->numa_node,
1481                                 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1482         if (!tags)
1483                 return NULL;
1484
1485         INIT_LIST_HEAD(&tags->page_list);
1486
1487         tags->rqs = kzalloc_node(set->queue_depth * sizeof(struct request *),
1488                                  GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
1489                                  set->numa_node);
1490         if (!tags->rqs) {
1491                 blk_mq_free_tags(tags);
1492                 return NULL;
1493         }
1494
1495         /*
1496          * rq_size is the size of the request plus driver payload, rounded
1497          * to the cacheline size
1498          */
1499         rq_size = round_up(sizeof(struct request) + set->cmd_size,
1500                                 cache_line_size());
1501         left = rq_size * set->queue_depth;
1502
1503         for (i = 0; i < set->queue_depth; ) {
1504                 int this_order = max_order;
1505                 struct page *page;
1506                 int to_do;
1507                 void *p;
1508
1509                 while (this_order && left < order_to_size(this_order - 1))
1510                         this_order--;
1511
1512                 do {
1513                         page = alloc_pages_node(set->numa_node,
1514                                 GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
1515                                 this_order);
1516                         if (page)
1517                                 break;
1518                         if (!this_order--)
1519                                 break;
1520                         if (order_to_size(this_order) < rq_size)
1521                                 break;
1522                 } while (1);
1523
1524                 if (!page)
1525                         goto fail;
1526
1527                 page->private = this_order;
1528                 list_add_tail(&page->lru, &tags->page_list);
1529
1530                 p = page_address(page);
1531                 /*
1532                  * Allow kmemleak to scan these pages as they contain pointers
1533                  * to additional allocations like via ops->init_request().
1534                  */
1535                 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_KERNEL);
1536                 entries_per_page = order_to_size(this_order) / rq_size;
1537                 to_do = min(entries_per_page, set->queue_depth - i);
1538                 left -= to_do * rq_size;
1539                 for (j = 0; j < to_do; j++) {
1540                         tags->rqs[i] = p;
1541                         if (set->ops->init_request) {
1542                                 if (set->ops->init_request(set->driver_data,
1543                                                 tags->rqs[i], hctx_idx, i,
1544                                                 set->numa_node)) {
1545                                         tags->rqs[i] = NULL;
1546                                         goto fail;
1547                                 }
1548                         }
1549
1550                         p += rq_size;
1551                         i++;
1552                 }
1553         }
1554         return tags;
1555
1556 fail:
1557         blk_mq_free_rq_map(set, tags, hctx_idx);
1558         return NULL;
1559 }
1560
1561 /*
1562  * 'cpu' is going away. splice any existing rq_list entries from this
1563  * software queue to the hw queue dispatch list, and ensure that it
1564  * gets run.
1565  */
1566 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
1567 {
1568         struct blk_mq_hw_ctx *hctx;
1569         struct blk_mq_ctx *ctx;
1570         LIST_HEAD(tmp);
1571
1572         hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
1573         ctx = __blk_mq_get_ctx(hctx->queue, cpu);
1574
1575         spin_lock(&ctx->lock);
1576         if (!list_empty(&ctx->rq_list)) {
1577                 list_splice_init(&ctx->rq_list, &tmp);
1578                 blk_mq_hctx_clear_pending(hctx, ctx);
1579         }
1580         spin_unlock(&ctx->lock);
1581
1582         if (list_empty(&tmp))
1583                 return 0;
1584
1585         spin_lock(&hctx->lock);
1586         list_splice_tail_init(&tmp, &hctx->dispatch);
1587         spin_unlock(&hctx->lock);
1588
1589         blk_mq_run_hw_queue(hctx, true);
1590         return 0;
1591 }
1592
1593 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
1594 {
1595         cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
1596                                             &hctx->cpuhp_dead);
1597 }
1598
1599 /* hctx->ctxs will be freed in queue's release handler */
1600 static void blk_mq_exit_hctx(struct request_queue *q,
1601                 struct blk_mq_tag_set *set,
1602                 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1603 {
1604         unsigned flush_start_tag = set->queue_depth;
1605
1606         blk_mq_tag_idle(hctx);
1607
1608         if (set->ops->exit_request)
1609                 set->ops->exit_request(set->driver_data,
1610                                        hctx->fq->flush_rq, hctx_idx,
1611                                        flush_start_tag + hctx_idx);
1612
1613         if (set->ops->exit_hctx)
1614                 set->ops->exit_hctx(hctx, hctx_idx);
1615
1616         blk_mq_remove_cpuhp(hctx);
1617         blk_free_flush_queue(hctx->fq);
1618         sbitmap_free(&hctx->ctx_map);
1619 }
1620
1621 static void blk_mq_exit_hw_queues(struct request_queue *q,
1622                 struct blk_mq_tag_set *set, int nr_queue)
1623 {
1624         struct blk_mq_hw_ctx *hctx;
1625         unsigned int i;
1626
1627         queue_for_each_hw_ctx(q, hctx, i) {
1628                 if (i == nr_queue)
1629                         break;
1630                 blk_mq_exit_hctx(q, set, hctx, i);
1631         }
1632 }
1633
1634 static void blk_mq_free_hw_queues(struct request_queue *q,
1635                 struct blk_mq_tag_set *set)
1636 {
1637         struct blk_mq_hw_ctx *hctx;
1638         unsigned int i;
1639
1640         queue_for_each_hw_ctx(q, hctx, i)
1641                 free_cpumask_var(hctx->cpumask);
1642 }
1643
1644 static int blk_mq_init_hctx(struct request_queue *q,
1645                 struct blk_mq_tag_set *set,
1646                 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
1647 {
1648         int node;
1649         unsigned flush_start_tag = set->queue_depth;
1650
1651         node = hctx->numa_node;
1652         if (node == NUMA_NO_NODE)
1653                 node = hctx->numa_node = set->numa_node;
1654
1655         INIT_WORK(&hctx->run_work, blk_mq_run_work_fn);
1656         INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
1657         spin_lock_init(&hctx->lock);
1658         INIT_LIST_HEAD(&hctx->dispatch);
1659         hctx->queue = q;
1660         hctx->queue_num = hctx_idx;
1661         hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
1662
1663         cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
1664
1665         hctx->tags = set->tags[hctx_idx];
1666
1667         /*
1668          * Allocate space for all possible cpus to avoid allocation at
1669          * runtime
1670          */
1671         hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1672                                         GFP_KERNEL, node);
1673         if (!hctx->ctxs)
1674                 goto unregister_cpu_notifier;
1675
1676         if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
1677                               node))
1678                 goto free_ctxs;
1679
1680         hctx->nr_ctx = 0;
1681
1682         if (set->ops->init_hctx &&
1683             set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
1684                 goto free_bitmap;
1685
1686         hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
1687         if (!hctx->fq)
1688                 goto exit_hctx;
1689
1690         if (set->ops->init_request &&
1691             set->ops->init_request(set->driver_data,
1692                                    hctx->fq->flush_rq, hctx_idx,
1693                                    flush_start_tag + hctx_idx, node))
1694                 goto free_fq;
1695
1696         return 0;
1697
1698  free_fq:
1699         kfree(hctx->fq);
1700  exit_hctx:
1701         if (set->ops->exit_hctx)
1702                 set->ops->exit_hctx(hctx, hctx_idx);
1703  free_bitmap:
1704         sbitmap_free(&hctx->ctx_map);
1705  free_ctxs:
1706         kfree(hctx->ctxs);
1707  unregister_cpu_notifier:
1708         blk_mq_remove_cpuhp(hctx);
1709         return -1;
1710 }
1711
1712 static void blk_mq_init_cpu_queues(struct request_queue *q,
1713                                    unsigned int nr_hw_queues)
1714 {
1715         unsigned int i;
1716
1717         for_each_possible_cpu(i) {
1718                 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1719                 struct blk_mq_hw_ctx *hctx;
1720
1721                 memset(__ctx, 0, sizeof(*__ctx));
1722                 __ctx->cpu = i;
1723                 spin_lock_init(&__ctx->lock);
1724                 INIT_LIST_HEAD(&__ctx->rq_list);
1725                 __ctx->queue = q;
1726
1727                 /* If the cpu isn't online, the cpu is mapped to first hctx */
1728                 if (!cpu_online(i))
1729                         continue;
1730
1731                 hctx = blk_mq_map_queue(q, i);
1732
1733                 /*
1734                  * Set local node, IFF we have more than one hw queue. If
1735                  * not, we remain on the home node of the device
1736                  */
1737                 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
1738                         hctx->numa_node = local_memory_node(cpu_to_node(i));
1739         }
1740 }
1741
1742 static void blk_mq_map_swqueue(struct request_queue *q,
1743                                const struct cpumask *online_mask)
1744 {
1745         unsigned int i;
1746         struct blk_mq_hw_ctx *hctx;
1747         struct blk_mq_ctx *ctx;
1748         struct blk_mq_tag_set *set = q->tag_set;
1749
1750         /*
1751          * Avoid others reading imcomplete hctx->cpumask through sysfs
1752          */
1753         mutex_lock(&q->sysfs_lock);
1754
1755         queue_for_each_hw_ctx(q, hctx, i) {
1756                 cpumask_clear(hctx->cpumask);
1757                 hctx->nr_ctx = 0;
1758         }
1759
1760         /*
1761          * Map software to hardware queues
1762          */
1763         for_each_possible_cpu(i) {
1764                 /* If the cpu isn't online, the cpu is mapped to first hctx */
1765                 if (!cpumask_test_cpu(i, online_mask))
1766                         continue;
1767
1768                 ctx = per_cpu_ptr(q->queue_ctx, i);
1769                 hctx = blk_mq_map_queue(q, i);
1770
1771                 cpumask_set_cpu(i, hctx->cpumask);
1772                 ctx->index_hw = hctx->nr_ctx;
1773                 hctx->ctxs[hctx->nr_ctx++] = ctx;
1774         }
1775
1776         mutex_unlock(&q->sysfs_lock);
1777
1778         queue_for_each_hw_ctx(q, hctx, i) {
1779                 /*
1780                  * If no software queues are mapped to this hardware queue,
1781                  * disable it and free the request entries.
1782                  */
1783                 if (!hctx->nr_ctx) {
1784                         if (set->tags[i]) {
1785                                 blk_mq_free_rq_map(set, set->tags[i], i);
1786                                 set->tags[i] = NULL;
1787                         }
1788                         hctx->tags = NULL;
1789                         continue;
1790                 }
1791
1792                 /* unmapped hw queue can be remapped after CPU topo changed */
1793                 if (!set->tags[i])
1794                         set->tags[i] = blk_mq_init_rq_map(set, i);
1795                 hctx->tags = set->tags[i];
1796                 WARN_ON(!hctx->tags);
1797
1798                 /*
1799                  * Set the map size to the number of mapped software queues.
1800                  * This is more accurate and more efficient than looping
1801                  * over all possibly mapped software queues.
1802                  */
1803                 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
1804
1805                 /*
1806                  * Initialize batch roundrobin counts
1807                  */
1808                 hctx->next_cpu = cpumask_first(hctx->cpumask);
1809                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1810         }
1811 }
1812
1813 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
1814 {
1815         struct blk_mq_hw_ctx *hctx;
1816         int i;
1817
1818         queue_for_each_hw_ctx(q, hctx, i) {
1819                 if (shared)
1820                         hctx->flags |= BLK_MQ_F_TAG_SHARED;
1821                 else
1822                         hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
1823         }
1824 }
1825
1826 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
1827 {
1828         struct request_queue *q;
1829
1830         list_for_each_entry(q, &set->tag_list, tag_set_list) {
1831                 blk_mq_freeze_queue(q);
1832                 queue_set_hctx_shared(q, shared);
1833                 blk_mq_unfreeze_queue(q);
1834         }
1835 }
1836
1837 static void blk_mq_del_queue_tag_set(struct request_queue *q)
1838 {
1839         struct blk_mq_tag_set *set = q->tag_set;
1840
1841         mutex_lock(&set->tag_list_lock);
1842         list_del_init(&q->tag_set_list);
1843         if (list_is_singular(&set->tag_list)) {
1844                 /* just transitioned to unshared */
1845                 set->flags &= ~BLK_MQ_F_TAG_SHARED;
1846                 /* update existing queue */
1847                 blk_mq_update_tag_set_depth(set, false);
1848         }
1849         mutex_unlock(&set->tag_list_lock);
1850 }
1851
1852 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
1853                                      struct request_queue *q)
1854 {
1855         q->tag_set = set;
1856
1857         mutex_lock(&set->tag_list_lock);
1858
1859         /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
1860         if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
1861                 set->flags |= BLK_MQ_F_TAG_SHARED;
1862                 /* update existing queue */
1863                 blk_mq_update_tag_set_depth(set, true);
1864         }
1865         if (set->flags & BLK_MQ_F_TAG_SHARED)
1866                 queue_set_hctx_shared(q, true);
1867         list_add_tail(&q->tag_set_list, &set->tag_list);
1868
1869         mutex_unlock(&set->tag_list_lock);
1870 }
1871
1872 /*
1873  * It is the actual release handler for mq, but we do it from
1874  * request queue's release handler for avoiding use-after-free
1875  * and headache because q->mq_kobj shouldn't have been introduced,
1876  * but we can't group ctx/kctx kobj without it.
1877  */
1878 void blk_mq_release(struct request_queue *q)
1879 {
1880         struct blk_mq_hw_ctx *hctx;
1881         unsigned int i;
1882
1883         /* hctx kobj stays in hctx */
1884         queue_for_each_hw_ctx(q, hctx, i) {
1885                 if (!hctx)
1886                         continue;
1887                 kfree(hctx->ctxs);
1888                 kfree(hctx);
1889         }
1890
1891         q->mq_map = NULL;
1892
1893         kfree(q->queue_hw_ctx);
1894
1895         /* ctx kobj stays in queue_ctx */
1896         free_percpu(q->queue_ctx);
1897 }
1898
1899 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
1900 {
1901         struct request_queue *uninit_q, *q;
1902
1903         uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
1904         if (!uninit_q)
1905                 return ERR_PTR(-ENOMEM);
1906
1907         q = blk_mq_init_allocated_queue(set, uninit_q);
1908         if (IS_ERR(q))
1909                 blk_cleanup_queue(uninit_q);
1910
1911         return q;
1912 }
1913 EXPORT_SYMBOL(blk_mq_init_queue);
1914
1915 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
1916                                                 struct request_queue *q)
1917 {
1918         int i, j;
1919         struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
1920
1921         blk_mq_sysfs_unregister(q);
1922         for (i = 0; i < set->nr_hw_queues; i++) {
1923                 int node;
1924
1925                 if (hctxs[i])
1926                         continue;
1927
1928                 node = blk_mq_hw_queue_to_node(q->mq_map, i);
1929                 hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
1930                                         GFP_KERNEL, node);
1931                 if (!hctxs[i])
1932                         break;
1933
1934                 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
1935                                                 node)) {
1936                         kfree(hctxs[i]);
1937                         hctxs[i] = NULL;
1938                         break;
1939                 }
1940
1941                 atomic_set(&hctxs[i]->nr_active, 0);
1942                 hctxs[i]->numa_node = node;
1943                 hctxs[i]->queue_num = i;
1944
1945                 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
1946                         free_cpumask_var(hctxs[i]->cpumask);
1947                         kfree(hctxs[i]);
1948                         hctxs[i] = NULL;
1949                         break;
1950                 }
1951                 blk_mq_hctx_kobj_init(hctxs[i]);
1952         }
1953         for (j = i; j < q->nr_hw_queues; j++) {
1954                 struct blk_mq_hw_ctx *hctx = hctxs[j];
1955
1956                 if (hctx) {
1957                         if (hctx->tags) {
1958                                 blk_mq_free_rq_map(set, hctx->tags, j);
1959                                 set->tags[j] = NULL;
1960                         }
1961                         blk_mq_exit_hctx(q, set, hctx, j);
1962                         free_cpumask_var(hctx->cpumask);
1963                         kobject_put(&hctx->kobj);
1964                         kfree(hctx->ctxs);
1965                         kfree(hctx);
1966                         hctxs[j] = NULL;
1967
1968                 }
1969         }
1970         q->nr_hw_queues = i;
1971         blk_mq_sysfs_register(q);
1972 }
1973
1974 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
1975                                                   struct request_queue *q)
1976 {
1977         /* mark the queue as mq asap */
1978         q->mq_ops = set->ops;
1979
1980         q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
1981         if (!q->queue_ctx)
1982                 goto err_exit;
1983
1984         q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
1985                                                 GFP_KERNEL, set->numa_node);
1986         if (!q->queue_hw_ctx)
1987                 goto err_percpu;
1988
1989         q->mq_map = set->mq_map;
1990
1991         blk_mq_realloc_hw_ctxs(set, q);
1992         if (!q->nr_hw_queues)
1993                 goto err_hctxs;
1994
1995         INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
1996         blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
1997
1998         q->nr_queues = nr_cpu_ids;
1999
2000         q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2001
2002         if (!(set->flags & BLK_MQ_F_SG_MERGE))
2003                 q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
2004
2005         q->sg_reserved_size = INT_MAX;
2006
2007         INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2008         INIT_LIST_HEAD(&q->requeue_list);
2009         spin_lock_init(&q->requeue_lock);
2010
2011         if (q->nr_hw_queues > 1)
2012                 blk_queue_make_request(q, blk_mq_make_request);
2013         else
2014                 blk_queue_make_request(q, blk_sq_make_request);
2015
2016         /*
2017          * Do this after blk_queue_make_request() overrides it...
2018          */
2019         q->nr_requests = set->queue_depth;
2020
2021         if (set->ops->complete)
2022                 blk_queue_softirq_done(q, set->ops->complete);
2023
2024         blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2025
2026         get_online_cpus();
2027         mutex_lock(&all_q_mutex);
2028
2029         list_add_tail(&q->all_q_node, &all_q_list);
2030         blk_mq_add_queue_tag_set(set, q);
2031         blk_mq_map_swqueue(q, cpu_online_mask);
2032
2033         mutex_unlock(&all_q_mutex);
2034         put_online_cpus();
2035
2036         return q;
2037
2038 err_hctxs:
2039         kfree(q->queue_hw_ctx);
2040 err_percpu:
2041         free_percpu(q->queue_ctx);
2042 err_exit:
2043         q->mq_ops = NULL;
2044         return ERR_PTR(-ENOMEM);
2045 }
2046 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2047
2048 void blk_mq_free_queue(struct request_queue *q)
2049 {
2050         struct blk_mq_tag_set   *set = q->tag_set;
2051
2052         mutex_lock(&all_q_mutex);
2053         list_del_init(&q->all_q_node);
2054         mutex_unlock(&all_q_mutex);
2055
2056         blk_mq_del_queue_tag_set(q);
2057
2058         blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2059         blk_mq_free_hw_queues(q, set);
2060 }
2061
2062 /* Basically redo blk_mq_init_queue with queue frozen */
2063 static void blk_mq_queue_reinit(struct request_queue *q,
2064                                 const struct cpumask *online_mask)
2065 {
2066         WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2067
2068         blk_mq_sysfs_unregister(q);
2069
2070         /*
2071          * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2072          * we should change hctx numa_node according to new topology (this
2073          * involves free and re-allocate memory, worthy doing?)
2074          */
2075
2076         blk_mq_map_swqueue(q, online_mask);
2077
2078         blk_mq_sysfs_register(q);
2079 }
2080
2081 /*
2082  * New online cpumask which is going to be set in this hotplug event.
2083  * Declare this cpumasks as global as cpu-hotplug operation is invoked
2084  * one-by-one and dynamically allocating this could result in a failure.
2085  */
2086 static struct cpumask cpuhp_online_new;
2087
2088 static void blk_mq_queue_reinit_work(void)
2089 {
2090         struct request_queue *q;
2091
2092         mutex_lock(&all_q_mutex);
2093         /*
2094          * We need to freeze and reinit all existing queues.  Freezing
2095          * involves synchronous wait for an RCU grace period and doing it
2096          * one by one may take a long time.  Start freezing all queues in
2097          * one swoop and then wait for the completions so that freezing can
2098          * take place in parallel.
2099          */
2100         list_for_each_entry(q, &all_q_list, all_q_node)
2101                 blk_mq_freeze_queue_start(q);
2102         list_for_each_entry(q, &all_q_list, all_q_node) {
2103                 blk_mq_freeze_queue_wait(q);
2104
2105                 /*
2106                  * timeout handler can't touch hw queue during the
2107                  * reinitialization
2108                  */
2109                 del_timer_sync(&q->timeout);
2110         }
2111
2112         list_for_each_entry(q, &all_q_list, all_q_node)
2113                 blk_mq_queue_reinit(q, &cpuhp_online_new);
2114
2115         list_for_each_entry(q, &all_q_list, all_q_node)
2116                 blk_mq_unfreeze_queue(q);
2117
2118         mutex_unlock(&all_q_mutex);
2119 }
2120
2121 static int blk_mq_queue_reinit_dead(unsigned int cpu)
2122 {
2123         cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2124         blk_mq_queue_reinit_work();
2125         return 0;
2126 }
2127
2128 /*
2129  * Before hotadded cpu starts handling requests, new mappings must be
2130  * established.  Otherwise, these requests in hw queue might never be
2131  * dispatched.
2132  *
2133  * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2134  * for CPU0, and ctx1 for CPU1).
2135  *
2136  * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2137  * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2138  *
2139  * And then while running hw queue, flush_busy_ctxs() finds bit0 is set in
2140  * pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2141  * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list
2142  * is ignored.
2143  */
2144 static int blk_mq_queue_reinit_prepare(unsigned int cpu)
2145 {
2146         cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2147         cpumask_set_cpu(cpu, &cpuhp_online_new);
2148         blk_mq_queue_reinit_work();
2149         return 0;
2150 }
2151
2152 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2153 {
2154         int i;
2155
2156         for (i = 0; i < set->nr_hw_queues; i++) {
2157                 set->tags[i] = blk_mq_init_rq_map(set, i);
2158                 if (!set->tags[i])
2159                         goto out_unwind;
2160         }
2161
2162         return 0;
2163
2164 out_unwind:
2165         while (--i >= 0)
2166                 blk_mq_free_rq_map(set, set->tags[i], i);
2167
2168         return -ENOMEM;
2169 }
2170
2171 /*
2172  * Allocate the request maps associated with this tag_set. Note that this
2173  * may reduce the depth asked for, if memory is tight. set->queue_depth
2174  * will be updated to reflect the allocated depth.
2175  */
2176 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2177 {
2178         unsigned int depth;
2179         int err;
2180
2181         depth = set->queue_depth;
2182         do {
2183                 err = __blk_mq_alloc_rq_maps(set);
2184                 if (!err)
2185                         break;
2186
2187                 set->queue_depth >>= 1;
2188                 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2189                         err = -ENOMEM;
2190                         break;
2191                 }
2192         } while (set->queue_depth);
2193
2194         if (!set->queue_depth || err) {
2195                 pr_err("blk-mq: failed to allocate request map\n");
2196                 return -ENOMEM;
2197         }
2198
2199         if (depth != set->queue_depth)
2200                 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2201                                                 depth, set->queue_depth);
2202
2203         return 0;
2204 }
2205
2206 /*
2207  * Alloc a tag set to be associated with one or more request queues.
2208  * May fail with EINVAL for various error conditions. May adjust the
2209  * requested depth down, if if it too large. In that case, the set
2210  * value will be stored in set->queue_depth.
2211  */
2212 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2213 {
2214         int ret;
2215
2216         BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2217
2218         if (!set->nr_hw_queues)
2219                 return -EINVAL;
2220         if (!set->queue_depth)
2221                 return -EINVAL;
2222         if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2223                 return -EINVAL;
2224
2225         if (!set->ops->queue_rq)
2226                 return -EINVAL;
2227
2228         if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2229                 pr_info("blk-mq: reduced tag depth to %u\n",
2230                         BLK_MQ_MAX_DEPTH);
2231                 set->queue_depth = BLK_MQ_MAX_DEPTH;
2232         }
2233
2234         /*
2235          * If a crashdump is active, then we are potentially in a very
2236          * memory constrained environment. Limit us to 1 queue and
2237          * 64 tags to prevent using too much memory.
2238          */
2239         if (is_kdump_kernel()) {
2240                 set->nr_hw_queues = 1;
2241                 set->queue_depth = min(64U, set->queue_depth);
2242         }
2243         /*
2244          * There is no use for more h/w queues than cpus.
2245          */
2246         if (set->nr_hw_queues > nr_cpu_ids)
2247                 set->nr_hw_queues = nr_cpu_ids;
2248
2249         set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2250                                  GFP_KERNEL, set->numa_node);
2251         if (!set->tags)
2252                 return -ENOMEM;
2253
2254         ret = -ENOMEM;
2255         set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
2256                         GFP_KERNEL, set->numa_node);
2257         if (!set->mq_map)
2258                 goto out_free_tags;
2259
2260         if (set->ops->map_queues)
2261                 ret = set->ops->map_queues(set);
2262         else
2263                 ret = blk_mq_map_queues(set);
2264         if (ret)
2265                 goto out_free_mq_map;
2266
2267         ret = blk_mq_alloc_rq_maps(set);
2268         if (ret)
2269                 goto out_free_mq_map;
2270
2271         mutex_init(&set->tag_list_lock);
2272         INIT_LIST_HEAD(&set->tag_list);
2273
2274         return 0;
2275
2276 out_free_mq_map:
2277         kfree(set->mq_map);
2278         set->mq_map = NULL;
2279 out_free_tags:
2280         kfree(set->tags);
2281         set->tags = NULL;
2282         return ret;
2283 }
2284 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2285
2286 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2287 {
2288         int i;
2289
2290         for (i = 0; i < nr_cpu_ids; i++) {
2291                 if (set->tags[i])
2292                         blk_mq_free_rq_map(set, set->tags[i], i);
2293         }
2294
2295         kfree(set->mq_map);
2296         set->mq_map = NULL;
2297
2298         kfree(set->tags);
2299         set->tags = NULL;
2300 }
2301 EXPORT_SYMBOL(blk_mq_free_tag_set);
2302
2303 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2304 {
2305         struct blk_mq_tag_set *set = q->tag_set;
2306         struct blk_mq_hw_ctx *hctx;
2307         int i, ret;
2308
2309         if (!set || nr > set->queue_depth)
2310                 return -EINVAL;
2311
2312         ret = 0;
2313         queue_for_each_hw_ctx(q, hctx, i) {
2314                 if (!hctx->tags)
2315                         continue;
2316                 ret = blk_mq_tag_update_depth(hctx->tags, nr);
2317                 if (ret)
2318                         break;
2319         }
2320
2321         if (!ret)
2322                 q->nr_requests = nr;
2323
2324         return ret;
2325 }
2326
2327 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2328 {
2329         struct request_queue *q;
2330
2331         if (nr_hw_queues > nr_cpu_ids)
2332                 nr_hw_queues = nr_cpu_ids;
2333         if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2334                 return;
2335
2336         list_for_each_entry(q, &set->tag_list, tag_set_list)
2337                 blk_mq_freeze_queue(q);
2338
2339         set->nr_hw_queues = nr_hw_queues;
2340         list_for_each_entry(q, &set->tag_list, tag_set_list) {
2341                 blk_mq_realloc_hw_ctxs(set, q);
2342
2343                 if (q->nr_hw_queues > 1)
2344                         blk_queue_make_request(q, blk_mq_make_request);
2345                 else
2346                         blk_queue_make_request(q, blk_sq_make_request);
2347
2348                 blk_mq_queue_reinit(q, cpu_online_mask);
2349         }
2350
2351         list_for_each_entry(q, &set->tag_list, tag_set_list)
2352                 blk_mq_unfreeze_queue(q);
2353 }
2354 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2355
2356 void blk_mq_disable_hotplug(void)
2357 {
2358         mutex_lock(&all_q_mutex);
2359 }
2360
2361 void blk_mq_enable_hotplug(void)
2362 {
2363         mutex_unlock(&all_q_mutex);
2364 }
2365
2366 static int __init blk_mq_init(void)
2367 {
2368         cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
2369                                 blk_mq_hctx_notify_dead);
2370
2371         cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE, "block/mq:prepare",
2372                                   blk_mq_queue_reinit_prepare,
2373                                   blk_mq_queue_reinit_dead);
2374         return 0;
2375 }
2376 subsys_initcall(blk_mq_init);