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                 return;
 634
 635         if (time_after_eq(jiffies, rq->deadline)) {
 636                 if (!blk_mark_rq_complete(rq))
 637                         blk_mq_rq_timed_out(rq, reserved);
 638         } else if (!data->next_set || time_after(data->next, rq->deadline)) {
 639                 data->next = rq->deadline;
 640                 data->next_set = 1;
 641         }
 642 }
 643
 644 static void blk_mq_timeout_work(struct work_struct *work)
 645 {
 646         struct request_queue *q =
 647                 container_of(work, struct request_queue, timeout_work);
 648         struct blk_mq_timeout_data data = {
 649                 .next           = 0,
 650                 .next_set       = 0,
 651         };
 652         int i;
 653
 654         /* A deadlock might occur if a request is stuck requiring a
 655          * timeout at the same time a queue freeze is waiting
 656          * completion, since the timeout code would not be able to
 657          * acquire the queue reference here.
 658          *
 659          * That's why we don't use blk_queue_enter here; instead, we use
 660          * percpu_ref_tryget directly, because we need to be able to
 661          * obtain a reference even in the short window between the queue
 662          * starting to freeze, by dropping the first reference in
 663          * blk_mq_freeze_queue_start, and the moment the last request is
 664          * consumed, marked by the instant q_usage_counter reaches
 665          * zero.
 666          */
 667         if (!percpu_ref_tryget(&q->q_usage_counter))
 668                 return;
 669
 670         blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
 671
 672         if (data.next_set) {
 673                 data.next = blk_rq_timeout(round_jiffies_up(data.next));
 674                 mod_timer(&q->timeout, data.next);
 675         } else {
 676                 struct blk_mq_hw_ctx *hctx;
 677
 678                 queue_for_each_hw_ctx(q, hctx, i) {
 679                         /* the hctx may be unmapped, so check it here */
 680                         if (blk_mq_hw_queue_mapped(hctx))
 681                                 blk_mq_tag_idle(hctx);
 682                 }
 683         }
 684         blk_queue_exit(q);
 685 }
 686
 687 /*
 688  * Reverse check our software queue for entries that we could potentially
 689  * merge with. Currently includes a hand-wavy stop count of 8, to not spend
 690  * too much time checking for merges.
 691  */
 692 static bool blk_mq_attempt_merge(struct request_queue *q,
 693                                  struct blk_mq_ctx *ctx, struct bio *bio)
 694 {
 695         struct request *rq;
 696         int checked = 8;
 697
 698         list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
 699                 int el_ret;
 700
 701                 if (!checked--)
 702                         break;
 703
 704                 if (!blk_rq_merge_ok(rq, bio))
 705                         continue;
 706
 707                 el_ret = blk_try_merge(rq, bio);
 708                 if (el_ret == ELEVATOR_BACK_MERGE) {
 709                         if (bio_attempt_back_merge(q, rq, bio)) {
 710                                 ctx->rq_merged++;
 711                                 return true;
 712                         }
 713                         break;
 714                 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
 715                         if (bio_attempt_front_merge(q, rq, bio)) {
 716                                 ctx->rq_merged++;
 717                                 return true;
 718                         }
 719                         break;
 720                 }
 721         }
 722
 723         return false;
 724 }
 725
 726 struct flush_busy_ctx_data {
 727         struct blk_mq_hw_ctx *hctx;
 728         struct list_head *list;
 729 };
 730
 731 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
 732 {
 733         struct flush_busy_ctx_data *flush_data = data;
 734         struct blk_mq_hw_ctx *hctx = flush_data->hctx;
 735         struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
 736
 737         sbitmap_clear_bit(sb, bitnr);
 738         spin_lock(&ctx->lock);
 739         list_splice_tail_init(&ctx->rq_list, flush_data->list);
 740         spin_unlock(&ctx->lock);
 741         return true;
 742 }
 743
 744 /*
 745  * Process software queues that have been marked busy, splicing them
 746  * to the for-dispatch
 747  */
 748 static void flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
 749 {
 750         struct flush_busy_ctx_data data = {
 751                 .hctx = hctx,
 752                 .list = list,
 753         };
 754
 755         sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
 756 }
 757
 758 static inline unsigned int queued_to_index(unsigned int queued)
 759 {
 760         if (!queued)
 761                 return 0;
 762
 763         return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
 764 }
 765
 766 /*
 767  * Run this hardware queue, pulling any software queues mapped to it in.
 768  * Note that this function currently has various problems around ordering
 769  * of IO. In particular, we'd like FIFO behaviour on handling existing
 770  * items on the hctx->dispatch list. Ignore that for now.
 771  */
 772 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
 773 {
 774         struct request_queue *q = hctx->queue;
 775         struct request *rq;
 776         LIST_HEAD(rq_list);
 777         LIST_HEAD(driver_list);
 778         struct list_head *dptr;
 779         int queued;
 780
 781         if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
 782                 return;
 783
 784         WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
 785                 cpu_online(hctx->next_cpu));
 786
 787         hctx->run++;
 788
 789         /*
 790          * Touch any software queue that has pending entries.
 791          */
 792         flush_busy_ctxs(hctx, &rq_list);
 793
 794         /*
 795          * If we have previous entries on our dispatch list, grab them
 796          * and stuff them at the front for more fair dispatch.
 797          */
 798         if (!list_empty_careful(&hctx->dispatch)) {
 799                 spin_lock(&hctx->lock);
 800                 if (!list_empty(&hctx->dispatch))
 801                         list_splice_init(&hctx->dispatch, &rq_list);
 802                 spin_unlock(&hctx->lock);
 803         }
 804
 805         /*
 806          * Start off with dptr being NULL, so we start the first request
 807          * immediately, even if we have more pending.
 808          */
 809         dptr = NULL;
 810
 811         /*
 812          * Now process all the entries, sending them to the driver.
 813          */
 814         queued = 0;
 815         while (!list_empty(&rq_list)) {
 816                 struct blk_mq_queue_data bd;
 817                 int ret;
 818
 819                 rq = list_first_entry(&rq_list, struct request, queuelist);
 820                 list_del_init(&rq->queuelist);
 821
 822                 bd.rq = rq;
 823                 bd.list = dptr;
 824                 bd.last = list_empty(&rq_list);
 825
 826                 ret = q->mq_ops->queue_rq(hctx, &bd);
 827                 switch (ret) {
 828                 case BLK_MQ_RQ_QUEUE_OK:
 829                         queued++;
 830                         break;
 831                 case BLK_MQ_RQ_QUEUE_BUSY:
 832                         list_add(&rq->queuelist, &rq_list);
 833                         __blk_mq_requeue_request(rq);
 834                         break;
 835                 default:
 836                         pr_err("blk-mq: bad return on queue: %d\n", ret);
 837                 case BLK_MQ_RQ_QUEUE_ERROR:
 838                         rq->errors = -EIO;
 839                         blk_mq_end_request(rq, rq->errors);
 840                         break;
 841                 }
 842
 843                 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
 844                         break;
 845
 846                 /*
 847                  * We've done the first request. If we have more than 1
 848                  * left in the list, set dptr to defer issue.
 849                  */
 850                 if (!dptr && rq_list.next != rq_list.prev)
 851                         dptr = &driver_list;
 852         }
 853
 854         hctx->dispatched[queued_to_index(queued)]++;
 855
 856         /*
 857          * Any items that need requeuing? Stuff them into hctx->dispatch,
 858          * that is where we will continue on next queue run.
 859          */
 860         if (!list_empty(&rq_list)) {
 861                 spin_lock(&hctx->lock);
 862                 list_splice(&rq_list, &hctx->dispatch);
 863                 spin_unlock(&hctx->lock);
 864                 /*
 865                  * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
 866                  * it's possible the queue is stopped and restarted again
 867                  * before this. Queue restart will dispatch requests. And since
 868                  * requests in rq_list aren't added into hctx->dispatch yet,
 869                  * the requests in rq_list might get lost.
 870                  *
 871                  * blk_mq_run_hw_queue() already checks the STOPPED bit
 872                  **/
 873                 blk_mq_run_hw_queue(hctx, true);
 874         }
 875 }
 876
 877 /*
 878  * It'd be great if the workqueue API had a way to pass
 879  * in a mask and had some smarts for more clever placement.
 880  * For now we just round-robin here, switching for every
 881  * BLK_MQ_CPU_WORK_BATCH queued items.
 882  */
 883 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
 884 {
 885         if (hctx->queue->nr_hw_queues == 1)
 886                 return WORK_CPU_UNBOUND;
 887
 888         if (--hctx->next_cpu_batch <= 0) {
 889                 int next_cpu;
 890
 891                 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
 892                 if (next_cpu >= nr_cpu_ids)
 893                         next_cpu = cpumask_first(hctx->cpumask);
 894
 895                 hctx->next_cpu = next_cpu;
 896                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
 897         }
 898
 899         return hctx->next_cpu;
 900 }
 901
 902 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
 903 {
 904         if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state) ||
 905             !blk_mq_hw_queue_mapped(hctx)))
 906                 return;
 907
 908         if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
 909                 int cpu = get_cpu();
 910                 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
 911                         __blk_mq_run_hw_queue(hctx);
 912                         put_cpu();
 913                         return;
 914                 }
 915
 916                 put_cpu();
 917         }
 918
 919         kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work);
 920 }
 921
 922 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
 923 {
 924         struct blk_mq_hw_ctx *hctx;
 925         int i;
 926
 927         queue_for_each_hw_ctx(q, hctx, i) {
 928                 if ((!blk_mq_hctx_has_pending(hctx) &&
 929                     list_empty_careful(&hctx->dispatch)) ||
 930                     test_bit(BLK_MQ_S_STOPPED, &hctx->state))
 931                         continue;
 932
 933                 blk_mq_run_hw_queue(hctx, async);
 934         }
 935 }
 936 EXPORT_SYMBOL(blk_mq_run_hw_queues);
 937
 938 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
 939 {
 940         cancel_work(&hctx->run_work);
 941         cancel_delayed_work(&hctx->delay_work);
 942         set_bit(BLK_MQ_S_STOPPED, &hctx->state);
 943 }
 944 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
 945
 946 void blk_mq_stop_hw_queues(struct request_queue *q)
 947 {
 948         struct blk_mq_hw_ctx *hctx;
 949         int i;
 950
 951         queue_for_each_hw_ctx(q, hctx, i)
 952                 blk_mq_stop_hw_queue(hctx);
 953 }
 954 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
 955
 956 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
 957 {
 958         clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
 959
 960         blk_mq_run_hw_queue(hctx, false);
 961 }
 962 EXPORT_SYMBOL(blk_mq_start_hw_queue);
 963
 964 void blk_mq_start_hw_queues(struct request_queue *q)
 965 {
 966         struct blk_mq_hw_ctx *hctx;
 967         int i;
 968
 969         queue_for_each_hw_ctx(q, hctx, i)
 970                 blk_mq_start_hw_queue(hctx);
 971 }
 972 EXPORT_SYMBOL(blk_mq_start_hw_queues);
 973
 974 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
 975 {
 976         struct blk_mq_hw_ctx *hctx;
 977         int i;
 978
 979         queue_for_each_hw_ctx(q, hctx, i) {
 980                 if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
 981                         continue;
 982
 983                 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
 984                 blk_mq_run_hw_queue(hctx, async);
 985         }
 986 }
 987 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
 988
 989 static void blk_mq_run_work_fn(struct work_struct *work)
 990 {
 991         struct blk_mq_hw_ctx *hctx;
 992
 993         hctx = container_of(work, struct blk_mq_hw_ctx, run_work);
 994
 995         __blk_mq_run_hw_queue(hctx);
 996 }
 997
 998 static void blk_mq_delay_work_fn(struct work_struct *work)
 999 {
1000         struct blk_mq_hw_ctx *hctx;
1001
1002         hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
1003
1004         if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
1005                 __blk_mq_run_hw_queue(hctx);
1006 }
1007
1008 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1009 {
1010         if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
1011                 return;
1012
1013         kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1014                         &hctx->delay_work, msecs_to_jiffies(msecs));
1015 }
1016 EXPORT_SYMBOL(blk_mq_delay_queue);
1017
1018 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1019                                             struct request *rq,
1020                                             bool at_head)
1021 {
1022         struct blk_mq_ctx *ctx = rq->mq_ctx;
1023
1024         trace_block_rq_insert(hctx->queue, rq);
1025
1026         if (at_head)
1027                 list_add(&rq->queuelist, &ctx->rq_list);
1028         else
1029                 list_add_tail(&rq->queuelist, &ctx->rq_list);
1030 }
1031
1032 static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
1033                                     struct request *rq, bool at_head)
1034 {
1035         struct blk_mq_ctx *ctx = rq->mq_ctx;
1036
1037         __blk_mq_insert_req_list(hctx, rq, at_head);
1038         blk_mq_hctx_mark_pending(hctx, ctx);
1039 }
1040
1041 void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
1042                            bool async)
1043 {
1044         struct blk_mq_ctx *ctx = rq->mq_ctx;
1045         struct request_queue *q = rq->q;
1046         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
1047
1048         spin_lock(&ctx->lock);
1049         __blk_mq_insert_request(hctx, rq, at_head);
1050         spin_unlock(&ctx->lock);
1051
1052         if (run_queue)
1053                 blk_mq_run_hw_queue(hctx, async);
1054 }
1055
1056 static void blk_mq_insert_requests(struct request_queue *q,
1057                                      struct blk_mq_ctx *ctx,
1058                                      struct list_head *list,
1059                                      int depth,
1060                                      bool from_schedule)
1061
1062 {
1063         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
1064
1065         trace_block_unplug(q, depth, !from_schedule);
1066
1067         /*
1068          * preemption doesn't flush plug list, so it's possible ctx->cpu is
1069          * offline now
1070          */
1071         spin_lock(&ctx->lock);
1072         while (!list_empty(list)) {
1073                 struct request *rq;
1074
1075                 rq = list_first_entry(list, struct request, queuelist);
1076                 BUG_ON(rq->mq_ctx != ctx);
1077                 list_del_init(&rq->queuelist);
1078                 __blk_mq_insert_req_list(hctx, rq, false);
1079         }
1080         blk_mq_hctx_mark_pending(hctx, ctx);
1081         spin_unlock(&ctx->lock);
1082
1083         blk_mq_run_hw_queue(hctx, from_schedule);
1084 }
1085
1086 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1087 {
1088         struct request *rqa = container_of(a, struct request, queuelist);
1089         struct request *rqb = container_of(b, struct request, queuelist);
1090
1091         return !(rqa->mq_ctx < rqb->mq_ctx ||
1092                  (rqa->mq_ctx == rqb->mq_ctx &&
1093                   blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1094 }
1095
1096 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1097 {
1098         struct blk_mq_ctx *this_ctx;
1099         struct request_queue *this_q;
1100         struct request *rq;
1101         LIST_HEAD(list);
1102         LIST_HEAD(ctx_list);
1103         unsigned int depth;
1104
1105         list_splice_init(&plug->mq_list, &list);
1106
1107         list_sort(NULL, &list, plug_ctx_cmp);
1108
1109         this_q = NULL;
1110         this_ctx = NULL;
1111         depth = 0;
1112
1113         while (!list_empty(&list)) {
1114                 rq = list_entry_rq(list.next);
1115                 list_del_init(&rq->queuelist);
1116                 BUG_ON(!rq->q);
1117                 if (rq->mq_ctx != this_ctx) {
1118                         if (this_ctx) {
1119                                 blk_mq_insert_requests(this_q, this_ctx,
1120                                                         &ctx_list, depth,
1121                                                         from_schedule);
1122                         }
1123
1124                         this_ctx = rq->mq_ctx;
1125                         this_q = rq->q;
1126                         depth = 0;
1127                 }
1128
1129                 depth++;
1130                 list_add_tail(&rq->queuelist, &ctx_list);
1131         }
1132
1133         /*
1134          * If 'this_ctx' is set, we know we have entries to complete
1135          * on 'ctx_list'. Do those.
1136          */
1137         if (this_ctx) {
1138                 blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
1139                                        from_schedule);
1140         }
1141 }
1142
1143 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1144 {
1145         init_request_from_bio(rq, bio);
1146
1147         blk_account_io_start(rq, 1);
1148 }
1149
1150 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
1151 {
1152         return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
1153                 !blk_queue_nomerges(hctx->queue);
1154 }
1155
1156 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
1157                                          struct blk_mq_ctx *ctx,
1158                                          struct request *rq, struct bio *bio)
1159 {
1160         if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
1161                 blk_mq_bio_to_request(rq, bio);
1162                 spin_lock(&ctx->lock);
1163 insert_rq:
1164                 __blk_mq_insert_request(hctx, rq, false);
1165                 spin_unlock(&ctx->lock);
1166                 return false;
1167         } else {
1168                 struct request_queue *q = hctx->queue;
1169
1170                 spin_lock(&ctx->lock);
1171                 if (!blk_mq_attempt_merge(q, ctx, bio)) {
1172                         blk_mq_bio_to_request(rq, bio);
1173                         goto insert_rq;
1174                 }
1175
1176                 spin_unlock(&ctx->lock);
1177                 __blk_mq_free_request(hctx, ctx, rq);
1178                 return true;
1179         }
1180 }
1181
1182 struct blk_map_ctx {
1183         struct blk_mq_hw_ctx *hctx;
1184         struct blk_mq_ctx *ctx;
1185 };
1186
1187 static struct request *blk_mq_map_request(struct request_queue *q,
1188                                           struct bio *bio,
1189                                           struct blk_map_ctx *data)
1190 {
1191         struct blk_mq_hw_ctx *hctx;
1192         struct blk_mq_ctx *ctx;
1193         struct request *rq;
1194         int op = bio_data_dir(bio);
1195         int op_flags = 0;
1196         struct blk_mq_alloc_data alloc_data;
1197
1198         blk_queue_enter_live(q);
1199         ctx = blk_mq_get_ctx(q);
1200         hctx = blk_mq_map_queue(q, ctx->cpu);
1201
1202         if (rw_is_sync(bio_op(bio), bio->bi_opf))
1203                 op_flags |= REQ_SYNC;
1204
1205         trace_block_getrq(q, bio, op);
1206         blk_mq_set_alloc_data(&alloc_data, q, 0, ctx, hctx);
1207         rq = __blk_mq_alloc_request(&alloc_data, op, op_flags);
1208
1209         data->hctx = alloc_data.hctx;
1210         data->ctx = alloc_data.ctx;
1211         data->hctx->queued++;
1212         return rq;
1213 }
1214
1215 static int blk_mq_direct_issue_request(struct request *rq, blk_qc_t *cookie)
1216 {
1217         int ret;
1218         struct request_queue *q = rq->q;
1219         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
1220         struct blk_mq_queue_data bd = {
1221                 .rq = rq,
1222                 .list = NULL,
1223                 .last = 1
1224         };
1225         blk_qc_t new_cookie = blk_tag_to_qc_t(rq->tag, hctx->queue_num);
1226
1227         /*
1228          * For OK queue, we are done. For error, kill it. Any other
1229          * error (busy), just add it to our list as we previously
1230          * would have done
1231          */
1232         ret = q->mq_ops->queue_rq(hctx, &bd);
1233         if (ret == BLK_MQ_RQ_QUEUE_OK) {
1234                 *cookie = new_cookie;
1235                 return 0;
1236         }
1237
1238         __blk_mq_requeue_request(rq);
1239
1240         if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
1241                 *cookie = BLK_QC_T_NONE;
1242                 rq->errors = -EIO;
1243                 blk_mq_end_request(rq, rq->errors);
1244                 return 0;
1245         }
1246
1247         return -1;
1248 }
1249
1250 /*
1251  * Multiple hardware queue variant. This will not use per-process plugs,
1252  * but will attempt to bypass the hctx queueing if we can go straight to
1253  * hardware for SYNC IO.
1254  */
1255 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1256 {
1257         const int is_sync = rw_is_sync(bio_op(bio), bio->bi_opf);
1258         const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
1259         struct blk_map_ctx data;
1260         struct request *rq;
1261         unsigned int request_count = 0;
1262         struct blk_plug *plug;
1263         struct request *same_queue_rq = NULL;
1264         blk_qc_t cookie;
1265
1266         blk_queue_bounce(q, &bio);
1267
1268         blk_queue_split(q, &bio, q->bio_split);
1269
1270         if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1271                 bio_io_error(bio);
1272                 return BLK_QC_T_NONE;
1273         }
1274
1275         if (!is_flush_fua && !blk_queue_nomerges(q) &&
1276             blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1277                 return BLK_QC_T_NONE;
1278
1279         rq = blk_mq_map_request(q, bio, &data);
1280         if (unlikely(!rq))
1281                 return BLK_QC_T_NONE;
1282
1283         cookie = blk_tag_to_qc_t(rq->tag, data.hctx->queue_num);
1284
1285         if (unlikely(is_flush_fua)) {
1286                 blk_mq_bio_to_request(rq, bio);
1287                 blk_insert_flush(rq);
1288                 goto run_queue;
1289         }
1290
1291         plug = current->plug;
1292         /*
1293          * If the driver supports defer issued based on 'last', then
1294          * queue it up like normal since we can potentially save some
1295          * CPU this way.
1296          */
1297         if (((plug && !blk_queue_nomerges(q)) || is_sync) &&
1298             !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
1299                 struct request *old_rq = NULL;
1300
1301                 blk_mq_bio_to_request(rq, bio);
1302
1303                 /*
1304                  * We do limited pluging. If the bio can be merged, do that.
1305                  * Otherwise the existing request in the plug list will be
1306                  * issued. So the plug list will have one request at most
1307                  */
1308                 if (plug) {
1309                         /*
1310                          * The plug list might get flushed before this. If that
1311                          * happens, same_queue_rq is invalid and plug list is
1312                          * empty
1313                          */
1314                         if (same_queue_rq && !list_empty(&plug->mq_list)) {
1315                                 old_rq = same_queue_rq;
1316                                 list_del_init(&old_rq->queuelist);
1317                         }
1318                         list_add_tail(&rq->queuelist, &plug->mq_list);
1319                 } else /* is_sync */
1320                         old_rq = rq;
1321                 blk_mq_put_ctx(data.ctx);
1322                 if (!old_rq)
1323                         goto done;
1324                 if (test_bit(BLK_MQ_S_STOPPED, &data.hctx->state) ||
1325                     blk_mq_direct_issue_request(old_rq, &cookie) != 0)
1326                         blk_mq_insert_request(old_rq, false, true, true);
1327                 goto done;
1328         }
1329
1330         if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1331                 /*
1332                  * For a SYNC request, send it to the hardware immediately. For
1333                  * an ASYNC request, just ensure that we run it later on. The
1334                  * latter allows for merging opportunities and more efficient
1335                  * dispatching.
1336                  */
1337 run_queue:
1338                 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1339         }
1340         blk_mq_put_ctx(data.ctx);
1341 done:
1342         return cookie;
1343 }
1344
1345 /*
1346  * Single hardware queue variant. This will attempt to use any per-process
1347  * plug for merging and IO deferral.
1348  */
1349 static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
1350 {
1351         const int is_sync = rw_is_sync(bio_op(bio), bio->bi_opf);
1352         const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
1353         struct blk_plug *plug;
1354         unsigned int request_count = 0;
1355         struct blk_map_ctx data;
1356         struct request *rq;
1357         blk_qc_t cookie;
1358
1359         blk_queue_bounce(q, &bio);
1360
1361         if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1362                 bio_io_error(bio);
1363                 return BLK_QC_T_NONE;
1364         }
1365
1366         blk_queue_split(q, &bio, q->bio_split);
1367
1368         if (!is_flush_fua && !blk_queue_nomerges(q)) {
1369                 if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
1370                         return BLK_QC_T_NONE;
1371         } else
1372                 request_count = blk_plug_queued_count(q);
1373
1374         rq = blk_mq_map_request(q, bio, &data);
1375         if (unlikely(!rq))
1376                 return BLK_QC_T_NONE;
1377
1378         cookie = blk_tag_to_qc_t(rq->tag, data.hctx->queue_num);
1379
1380         if (unlikely(is_flush_fua)) {
1381                 blk_mq_bio_to_request(rq, bio);
1382                 blk_insert_flush(rq);
1383                 goto run_queue;
1384         }
1385
1386         /*
1387          * A task plug currently exists. Since this is completely lockless,
1388          * utilize that to temporarily store requests until the task is
1389          * either done or scheduled away.
1390          */
1391         plug = current->plug;
1392         if (plug) {
1393                 blk_mq_bio_to_request(rq, bio);
1394                 if (!request_count)
1395                         trace_block_plug(q);
1396
1397                 blk_mq_put_ctx(data.ctx);
1398
1399                 if (request_count >= BLK_MAX_REQUEST_COUNT) {
1400                         blk_flush_plug_list(plug, false);
1401                         trace_block_plug(q);
1402                 }
1403
1404                 list_add_tail(&rq->queuelist, &plug->mq_list);
1405                 return cookie;
1406         }
1407
1408         if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1409                 /*
1410                  * For a SYNC request, send it to the hardware immediately. For
1411                  * an ASYNC request, just ensure that we run it later on. The
1412                  * latter allows for merging opportunities and more efficient
1413                  * dispatching.
1414                  */
1415 run_queue:
1416                 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1417         }
1418
1419         blk_mq_put_ctx(data.ctx);
1420         return cookie;
1421 }
1422
1423 static void blk_mq_free_rq_map(struct blk_mq_tag_set *set,
1424                 struct blk_mq_tags *tags, unsigned int hctx_idx)
1425 {
1426         struct page *page;
1427
1428         if (tags->rqs && set->ops->exit_request) {
1429                 int i;
1430
1431                 for (i = 0; i < tags->nr_tags; i++) {
1432                         if (!tags->rqs[i])
1433                                 continue;
1434                         set->ops->exit_request(set->driver_data, tags->rqs[i],
1435                                                 hctx_idx, i);
1436                         tags->rqs[i] = NULL;
1437                 }
1438         }
1439
1440         while (!list_empty(&tags->page_list)) {
1441                 page = list_first_entry(&tags->page_list, struct page, lru);
1442                 list_del_init(&page->lru);
1443                 /*
1444                  * Remove kmemleak object previously allocated in
1445                  * blk_mq_init_rq_map().
1446                  */
1447                 kmemleak_free(page_address(page));
1448                 __free_pages(page, page->private);
1449         }
1450
1451         kfree(tags->rqs);
1452
1453         blk_mq_free_tags(tags);
1454 }
1455
1456 static size_t order_to_size(unsigned int order)
1457 {
1458         return (size_t)PAGE_SIZE << order;
1459 }
1460
1461 static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
1462                 unsigned int hctx_idx)
1463 {
1464         struct blk_mq_tags *tags;
1465         unsigned int i, j, entries_per_page, max_order = 4;
1466         size_t rq_size, left;
1467
1468         tags = blk_mq_init_tags(set->queue_depth, set->reserved_tags,
1469                                 set->numa_node,
1470                                 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1471         if (!tags)
1472                 return NULL;
1473
1474         INIT_LIST_HEAD(&tags->page_list);
1475
1476         tags->rqs = kzalloc_node(set->queue_depth * sizeof(struct request *),
1477                                  GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1478                                  set->numa_node);
1479         if (!tags->rqs) {
1480                 blk_mq_free_tags(tags);
1481                 return NULL;
1482         }
1483
1484         /*
1485          * rq_size is the size of the request plus driver payload, rounded
1486          * to the cacheline size
1487          */
1488         rq_size = round_up(sizeof(struct request) + set->cmd_size,
1489                                 cache_line_size());
1490         left = rq_size * set->queue_depth;
1491
1492         for (i = 0; i < set->queue_depth; ) {
1493                 int this_order = max_order;
1494                 struct page *page;
1495                 int to_do;
1496                 void *p;
1497
1498                 while (this_order && left < order_to_size(this_order - 1))
1499                         this_order--;
1500
1501                 do {
1502                         page = alloc_pages_node(set->numa_node,
1503                                 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
1504                                 this_order);
1505                         if (page)
1506                                 break;
1507                         if (!this_order--)
1508                                 break;
1509                         if (order_to_size(this_order) < rq_size)
1510                                 break;
1511                 } while (1);
1512
1513                 if (!page)
1514                         goto fail;
1515
1516                 page->private = this_order;
1517                 list_add_tail(&page->lru, &tags->page_list);
1518
1519                 p = page_address(page);
1520                 /*
1521                  * Allow kmemleak to scan these pages as they contain pointers
1522                  * to additional allocations like via ops->init_request().
1523                  */
1524                 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
1525                 entries_per_page = order_to_size(this_order) / rq_size;
1526                 to_do = min(entries_per_page, set->queue_depth - i);
1527                 left -= to_do * rq_size;
1528                 for (j = 0; j < to_do; j++) {
1529                         tags->rqs[i] = p;
1530                         if (set->ops->init_request) {
1531                                 if (set->ops->init_request(set->driver_data,
1532                                                 tags->rqs[i], hctx_idx, i,
1533                                                 set->numa_node)) {
1534                                         tags->rqs[i] = NULL;
1535                                         goto fail;
1536                                 }
1537                         }
1538
1539                         p += rq_size;
1540                         i++;
1541                 }
1542         }
1543         return tags;
1544
1545 fail:
1546         blk_mq_free_rq_map(set, tags, hctx_idx);
1547         return NULL;
1548 }
1549
1550 /*
1551  * 'cpu' is going away. splice any existing rq_list entries from this
1552  * software queue to the hw queue dispatch list, and ensure that it
1553  * gets run.
1554  */
1555 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
1556 {
1557         struct blk_mq_hw_ctx *hctx;
1558         struct blk_mq_ctx *ctx;
1559         LIST_HEAD(tmp);
1560
1561         hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
1562         ctx = __blk_mq_get_ctx(hctx->queue, cpu);
1563
1564         spin_lock(&ctx->lock);
1565         if (!list_empty(&ctx->rq_list)) {
1566                 list_splice_init(&ctx->rq_list, &tmp);
1567                 blk_mq_hctx_clear_pending(hctx, ctx);
1568         }
1569         spin_unlock(&ctx->lock);
1570
1571         if (list_empty(&tmp))
1572                 return 0;
1573
1574         spin_lock(&hctx->lock);
1575         list_splice_tail_init(&tmp, &hctx->dispatch);
1576         spin_unlock(&hctx->lock);
1577
1578         blk_mq_run_hw_queue(hctx, true);
1579         return 0;
1580 }
1581
1582 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
1583 {
1584         cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
1585                                             &hctx->cpuhp_dead);
1586 }
1587
1588 /* hctx->ctxs will be freed in queue's release handler */
1589 static void blk_mq_exit_hctx(struct request_queue *q,
1590                 struct blk_mq_tag_set *set,
1591                 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1592 {
1593         unsigned flush_start_tag = set->queue_depth;
1594
1595         if (blk_mq_hw_queue_mapped(hctx))
1596                 blk_mq_tag_idle(hctx);
1597
1598         if (set->ops->exit_request)
1599                 set->ops->exit_request(set->driver_data,
1600                                        hctx->fq->flush_rq, hctx_idx,
1601                                        flush_start_tag + hctx_idx);
1602
1603         if (set->ops->exit_hctx)
1604                 set->ops->exit_hctx(hctx, hctx_idx);
1605
1606         blk_mq_remove_cpuhp(hctx);
1607         blk_free_flush_queue(hctx->fq);
1608         sbitmap_free(&hctx->ctx_map);
1609 }
1610
1611 static void blk_mq_exit_hw_queues(struct request_queue *q,
1612                 struct blk_mq_tag_set *set, int nr_queue)
1613 {
1614         struct blk_mq_hw_ctx *hctx;
1615         unsigned int i;
1616
1617         queue_for_each_hw_ctx(q, hctx, i) {
1618                 if (i == nr_queue)
1619                         break;
1620                 blk_mq_exit_hctx(q, set, hctx, i);
1621         }
1622 }
1623
1624 static void blk_mq_free_hw_queues(struct request_queue *q,
1625                 struct blk_mq_tag_set *set)
1626 {
1627         struct blk_mq_hw_ctx *hctx;
1628         unsigned int i;
1629
1630         queue_for_each_hw_ctx(q, hctx, i)
1631                 free_cpumask_var(hctx->cpumask);
1632 }
1633
1634 static int blk_mq_init_hctx(struct request_queue *q,
1635                 struct blk_mq_tag_set *set,
1636                 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
1637 {
1638         int node;
1639         unsigned flush_start_tag = set->queue_depth;
1640
1641         node = hctx->numa_node;
1642         if (node == NUMA_NO_NODE)
1643                 node = hctx->numa_node = set->numa_node;
1644
1645         INIT_WORK(&hctx->run_work, blk_mq_run_work_fn);
1646         INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
1647         spin_lock_init(&hctx->lock);
1648         INIT_LIST_HEAD(&hctx->dispatch);
1649         hctx->queue = q;
1650         hctx->queue_num = hctx_idx;
1651         hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
1652
1653         cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
1654
1655         hctx->tags = set->tags[hctx_idx];
1656
1657         /*
1658          * Allocate space for all possible cpus to avoid allocation at
1659          * runtime
1660          */
1661         hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1662                                         GFP_KERNEL, node);
1663         if (!hctx->ctxs)
1664                 goto unregister_cpu_notifier;
1665
1666         if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
1667                               node))
1668                 goto free_ctxs;
1669
1670         hctx->nr_ctx = 0;
1671
1672         if (set->ops->init_hctx &&
1673             set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
1674                 goto free_bitmap;
1675
1676         hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
1677         if (!hctx->fq)
1678                 goto exit_hctx;
1679
1680         if (set->ops->init_request &&
1681             set->ops->init_request(set->driver_data,
1682                                    hctx->fq->flush_rq, hctx_idx,
1683                                    flush_start_tag + hctx_idx, node))
1684                 goto free_fq;
1685
1686         return 0;
1687
1688  free_fq:
1689         kfree(hctx->fq);
1690  exit_hctx:
1691         if (set->ops->exit_hctx)
1692                 set->ops->exit_hctx(hctx, hctx_idx);
1693  free_bitmap:
1694         sbitmap_free(&hctx->ctx_map);
1695  free_ctxs:
1696         kfree(hctx->ctxs);
1697  unregister_cpu_notifier:
1698         blk_mq_remove_cpuhp(hctx);
1699         return -1;
1700 }
1701
1702 static void blk_mq_init_cpu_queues(struct request_queue *q,
1703                                    unsigned int nr_hw_queues)
1704 {
1705         unsigned int i;
1706
1707         for_each_possible_cpu(i) {
1708                 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1709                 struct blk_mq_hw_ctx *hctx;
1710
1711                 __ctx->cpu = i;
1712                 spin_lock_init(&__ctx->lock);
1713                 INIT_LIST_HEAD(&__ctx->rq_list);
1714                 __ctx->queue = q;
1715
1716                 /* If the cpu isn't online, the cpu is mapped to first hctx */
1717                 if (!cpu_online(i))
1718                         continue;
1719
1720                 hctx = blk_mq_map_queue(q, i);
1721
1722                 /*
1723                  * Set local node, IFF we have more than one hw queue. If
1724                  * not, we remain on the home node of the device
1725                  */
1726                 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
1727                         hctx->numa_node = local_memory_node(cpu_to_node(i));
1728         }
1729 }
1730
1731 static void blk_mq_map_swqueue(struct request_queue *q,
1732                                const struct cpumask *online_mask)
1733 {
1734         unsigned int i;
1735         struct blk_mq_hw_ctx *hctx;
1736         struct blk_mq_ctx *ctx;
1737         struct blk_mq_tag_set *set = q->tag_set;
1738
1739         /*
1740          * Avoid others reading imcomplete hctx->cpumask through sysfs
1741          */
1742         mutex_lock(&q->sysfs_lock);
1743
1744         queue_for_each_hw_ctx(q, hctx, i) {
1745                 cpumask_clear(hctx->cpumask);
1746                 hctx->nr_ctx = 0;
1747         }
1748
1749         /*
1750          * Map software to hardware queues
1751          */
1752         for_each_possible_cpu(i) {
1753                 /* If the cpu isn't online, the cpu is mapped to first hctx */
1754                 if (!cpumask_test_cpu(i, online_mask))
1755                         continue;
1756
1757                 ctx = per_cpu_ptr(q->queue_ctx, i);
1758                 hctx = blk_mq_map_queue(q, i);
1759
1760                 cpumask_set_cpu(i, hctx->cpumask);
1761                 ctx->index_hw = hctx->nr_ctx;
1762                 hctx->ctxs[hctx->nr_ctx++] = ctx;
1763         }
1764
1765         mutex_unlock(&q->sysfs_lock);
1766
1767         queue_for_each_hw_ctx(q, hctx, i) {
1768                 /*
1769                  * If no software queues are mapped to this hardware queue,
1770                  * disable it and free the request entries.
1771                  */
1772                 if (!hctx->nr_ctx) {
1773                         if (set->tags[i]) {
1774                                 blk_mq_free_rq_map(set, set->tags[i], i);
1775                                 set->tags[i] = NULL;
1776                         }
1777                         hctx->tags = NULL;
1778                         continue;
1779                 }
1780
1781                 /* unmapped hw queue can be remapped after CPU topo changed */
1782                 if (!set->tags[i])
1783                         set->tags[i] = blk_mq_init_rq_map(set, i);
1784                 hctx->tags = set->tags[i];
1785                 WARN_ON(!hctx->tags);
1786
1787                 /*
1788                  * Set the map size to the number of mapped software queues.
1789                  * This is more accurate and more efficient than looping
1790                  * over all possibly mapped software queues.
1791                  */
1792                 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
1793
1794                 /*
1795                  * Initialize batch roundrobin counts
1796                  */
1797                 hctx->next_cpu = cpumask_first(hctx->cpumask);
1798                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1799         }
1800 }
1801
1802 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
1803 {
1804         struct blk_mq_hw_ctx *hctx;
1805         int i;
1806
1807         queue_for_each_hw_ctx(q, hctx, i) {
1808                 if (shared)
1809                         hctx->flags |= BLK_MQ_F_TAG_SHARED;
1810                 else
1811                         hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
1812         }
1813 }
1814
1815 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
1816 {
1817         struct request_queue *q;
1818
1819         list_for_each_entry(q, &set->tag_list, tag_set_list) {
1820                 blk_mq_freeze_queue(q);
1821                 queue_set_hctx_shared(q, shared);
1822                 blk_mq_unfreeze_queue(q);
1823         }
1824 }
1825
1826 static void blk_mq_del_queue_tag_set(struct request_queue *q)
1827 {
1828         struct blk_mq_tag_set *set = q->tag_set;
1829
1830         mutex_lock(&set->tag_list_lock);
1831         list_del_init(&q->tag_set_list);
1832         if (list_is_singular(&set->tag_list)) {
1833                 /* just transitioned to unshared */
1834                 set->flags &= ~BLK_MQ_F_TAG_SHARED;
1835                 /* update existing queue */
1836                 blk_mq_update_tag_set_depth(set, false);
1837         }
1838         mutex_unlock(&set->tag_list_lock);
1839 }
1840
1841 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
1842                                      struct request_queue *q)
1843 {
1844         q->tag_set = set;
1845
1846         mutex_lock(&set->tag_list_lock);
1847
1848         /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
1849         if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
1850                 set->flags |= BLK_MQ_F_TAG_SHARED;
1851                 /* update existing queue */
1852                 blk_mq_update_tag_set_depth(set, true);
1853         }
1854         if (set->flags & BLK_MQ_F_TAG_SHARED)
1855                 queue_set_hctx_shared(q, true);
1856         list_add_tail(&q->tag_set_list, &set->tag_list);
1857
1858         mutex_unlock(&set->tag_list_lock);
1859 }
1860
1861 /*
1862  * It is the actual release handler for mq, but we do it from
1863  * request queue's release handler for avoiding use-after-free
1864  * and headache because q->mq_kobj shouldn't have been introduced,
1865  * but we can't group ctx/kctx kobj without it.
1866  */
1867 void blk_mq_release(struct request_queue *q)
1868 {
1869         struct blk_mq_hw_ctx *hctx;
1870         unsigned int i;
1871
1872         /* hctx kobj stays in hctx */
1873         queue_for_each_hw_ctx(q, hctx, i) {
1874                 if (!hctx)
1875                         continue;
1876                 kfree(hctx->ctxs);
1877                 kfree(hctx);
1878         }
1879
1880         q->mq_map = NULL;
1881
1882         kfree(q->queue_hw_ctx);
1883
1884         /* ctx kobj stays in queue_ctx */
1885         free_percpu(q->queue_ctx);
1886 }
1887
1888 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
1889 {
1890         struct request_queue *uninit_q, *q;
1891
1892         uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
1893         if (!uninit_q)
1894                 return ERR_PTR(-ENOMEM);
1895
1896         q = blk_mq_init_allocated_queue(set, uninit_q);
1897         if (IS_ERR(q))
1898                 blk_cleanup_queue(uninit_q);
1899
1900         return q;
1901 }
1902 EXPORT_SYMBOL(blk_mq_init_queue);
1903
1904 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
1905                                                 struct request_queue *q)
1906 {
1907         int i, j;
1908         struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
1909
1910         blk_mq_sysfs_unregister(q);
1911
1912         /* protect against switching io scheduler  */
1913         mutex_lock(&q->sysfs_lock);
1914         for (i = 0; i < set->nr_hw_queues; i++) {
1915                 int node;
1916
1917                 if (hctxs[i])
1918                         continue;
1919
1920                 node = blk_mq_hw_queue_to_node(q->mq_map, i);
1921                 hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
1922                                         GFP_KERNEL, node);
1923                 if (!hctxs[i])
1924                         break;
1925
1926                 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
1927                                                 node)) {
1928                         kfree(hctxs[i]);
1929                         hctxs[i] = NULL;
1930                         break;
1931                 }
1932
1933                 atomic_set(&hctxs[i]->nr_active, 0);
1934                 hctxs[i]->numa_node = node;
1935                 hctxs[i]->queue_num = i;
1936
1937                 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
1938                         free_cpumask_var(hctxs[i]->cpumask);
1939                         kfree(hctxs[i]);
1940                         hctxs[i] = NULL;
1941                         break;
1942                 }
1943                 blk_mq_hctx_kobj_init(hctxs[i]);
1944         }
1945         for (j = i; j < q->nr_hw_queues; j++) {
1946                 struct blk_mq_hw_ctx *hctx = hctxs[j];
1947
1948                 if (hctx) {
1949                         if (hctx->tags) {
1950                                 blk_mq_free_rq_map(set, hctx->tags, j);
1951                                 set->tags[j] = NULL;
1952                         }
1953                         blk_mq_exit_hctx(q, set, hctx, j);
1954                         free_cpumask_var(hctx->cpumask);
1955                         kobject_put(&hctx->kobj);
1956                         kfree(hctx->ctxs);
1957                         kfree(hctx);
1958                         hctxs[j] = NULL;
1959
1960                 }
1961         }
1962         q->nr_hw_queues = i;
1963         mutex_unlock(&q->sysfs_lock);
1964         blk_mq_sysfs_register(q);
1965 }
1966
1967 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
1968                                                   struct request_queue *q)
1969 {
1970         /* mark the queue as mq asap */
1971         q->mq_ops = set->ops;
1972
1973         q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
1974         if (!q->queue_ctx)
1975                 goto err_exit;
1976
1977         /* init q->mq_kobj and sw queues' kobjects */
1978         blk_mq_sysfs_init(q);
1979
1980         q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
1981                                                 GFP_KERNEL, set->numa_node);
1982         if (!q->queue_hw_ctx)
1983                 goto err_percpu;
1984
1985         q->mq_map = set->mq_map;
1986
1987         blk_mq_realloc_hw_ctxs(set, q);
1988         if (!q->nr_hw_queues)
1989                 goto err_hctxs;
1990
1991         INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
1992         blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
1993
1994         q->nr_queues = nr_cpu_ids;
1995
1996         q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
1997
1998         if (!(set->flags & BLK_MQ_F_SG_MERGE))
1999                 q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
2000
2001         q->sg_reserved_size = INT_MAX;
2002
2003         INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2004         INIT_LIST_HEAD(&q->requeue_list);
2005         spin_lock_init(&q->requeue_lock);
2006
2007         if (q->nr_hw_queues > 1)
2008                 blk_queue_make_request(q, blk_mq_make_request);
2009         else
2010                 blk_queue_make_request(q, blk_sq_make_request);
2011
2012         /*
2013          * Do this after blk_queue_make_request() overrides it...
2014          */
2015         q->nr_requests = set->queue_depth;
2016
2017         if (set->ops->complete)
2018                 blk_queue_softirq_done(q, set->ops->complete);
2019
2020         blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2021
2022         get_online_cpus();
2023         mutex_lock(&all_q_mutex);
2024
2025         list_add_tail(&q->all_q_node, &all_q_list);
2026         blk_mq_add_queue_tag_set(set, q);
2027         blk_mq_map_swqueue(q, cpu_online_mask);
2028
2029         mutex_unlock(&all_q_mutex);
2030         put_online_cpus();
2031
2032         return q;
2033
2034 err_hctxs:
2035         kfree(q->queue_hw_ctx);
2036 err_percpu:
2037         free_percpu(q->queue_ctx);
2038 err_exit:
2039         q->mq_ops = NULL;
2040         return ERR_PTR(-ENOMEM);
2041 }
2042 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2043
2044 void blk_mq_free_queue(struct request_queue *q)
2045 {
2046         struct blk_mq_tag_set   *set = q->tag_set;
2047
2048         mutex_lock(&all_q_mutex);
2049         list_del_init(&q->all_q_node);
2050         mutex_unlock(&all_q_mutex);
2051
2052         blk_mq_del_queue_tag_set(q);
2053
2054         blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2055         blk_mq_free_hw_queues(q, set);
2056 }
2057
2058 /* Basically redo blk_mq_init_queue with queue frozen */
2059 static void blk_mq_queue_reinit(struct request_queue *q,
2060                                 const struct cpumask *online_mask)
2061 {
2062         WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2063
2064         blk_mq_sysfs_unregister(q);
2065
2066         /*
2067          * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2068          * we should change hctx numa_node according to new topology (this
2069          * involves free and re-allocate memory, worthy doing?)
2070          */
2071
2072         blk_mq_map_swqueue(q, online_mask);
2073
2074         blk_mq_sysfs_register(q);
2075 }
2076
2077 /*
2078  * New online cpumask which is going to be set in this hotplug event.
2079  * Declare this cpumasks as global as cpu-hotplug operation is invoked
2080  * one-by-one and dynamically allocating this could result in a failure.
2081  */
2082 static struct cpumask cpuhp_online_new;
2083
2084 static void blk_mq_queue_reinit_work(void)
2085 {
2086         struct request_queue *q;
2087
2088         mutex_lock(&all_q_mutex);
2089         /*
2090          * We need to freeze and reinit all existing queues.  Freezing
2091          * involves synchronous wait for an RCU grace period and doing it
2092          * one by one may take a long time.  Start freezing all queues in
2093          * one swoop and then wait for the completions so that freezing can
2094          * take place in parallel.
2095          */
2096         list_for_each_entry(q, &all_q_list, all_q_node)
2097                 blk_mq_freeze_queue_start(q);
2098         list_for_each_entry(q, &all_q_list, all_q_node) {
2099                 blk_mq_freeze_queue_wait(q);
2100
2101                 /*
2102                  * timeout handler can't touch hw queue during the
2103                  * reinitialization
2104                  */
2105                 del_timer_sync(&q->timeout);
2106         }
2107
2108         list_for_each_entry(q, &all_q_list, all_q_node)
2109                 blk_mq_queue_reinit(q, &cpuhp_online_new);
2110
2111         list_for_each_entry(q, &all_q_list, all_q_node)
2112                 blk_mq_unfreeze_queue(q);
2113
2114         mutex_unlock(&all_q_mutex);
2115 }
2116
2117 static int blk_mq_queue_reinit_dead(unsigned int cpu)
2118 {
2119         cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2120         blk_mq_queue_reinit_work();
2121         return 0;
2122 }
2123
2124 /*
2125  * Before hotadded cpu starts handling requests, new mappings must be
2126  * established.  Otherwise, these requests in hw queue might never be
2127  * dispatched.
2128  *
2129  * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2130  * for CPU0, and ctx1 for CPU1).
2131  *
2132  * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2133  * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2134  *
2135  * And then while running hw queue, flush_busy_ctxs() finds bit0 is set in
2136  * pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2137  * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list
2138  * is ignored.
2139  */
2140 static int blk_mq_queue_reinit_prepare(unsigned int cpu)
2141 {
2142         cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2143         cpumask_set_cpu(cpu, &cpuhp_online_new);
2144         blk_mq_queue_reinit_work();
2145         return 0;
2146 }
2147
2148 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2149 {
2150         int i;
2151
2152         for (i = 0; i < set->nr_hw_queues; i++) {
2153                 set->tags[i] = blk_mq_init_rq_map(set, i);
2154                 if (!set->tags[i])
2155                         goto out_unwind;
2156         }
2157
2158         return 0;
2159
2160 out_unwind:
2161         while (--i >= 0)
2162                 blk_mq_free_rq_map(set, set->tags[i], i);
2163
2164         return -ENOMEM;
2165 }
2166
2167 /*
2168  * Allocate the request maps associated with this tag_set. Note that this
2169  * may reduce the depth asked for, if memory is tight. set->queue_depth
2170  * will be updated to reflect the allocated depth.
2171  */
2172 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2173 {
2174         unsigned int depth;
2175         int err;
2176
2177         depth = set->queue_depth;
2178         do {
2179                 err = __blk_mq_alloc_rq_maps(set);
2180                 if (!err)
2181                         break;
2182
2183                 set->queue_depth >>= 1;
2184                 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2185                         err = -ENOMEM;
2186                         break;
2187                 }
2188         } while (set->queue_depth);
2189
2190         if (!set->queue_depth || err) {
2191                 pr_err("blk-mq: failed to allocate request map\n");
2192                 return -ENOMEM;
2193         }
2194
2195         if (depth != set->queue_depth)
2196                 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2197                                                 depth, set->queue_depth);
2198
2199         return 0;
2200 }
2201
2202 /*
2203  * Alloc a tag set to be associated with one or more request queues.
2204  * May fail with EINVAL for various error conditions. May adjust the
2205  * requested depth down, if if it too large. In that case, the set
2206  * value will be stored in set->queue_depth.
2207  */
2208 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2209 {
2210         int ret;
2211
2212         BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2213
2214         if (!set->nr_hw_queues)
2215                 return -EINVAL;
2216         if (!set->queue_depth)
2217                 return -EINVAL;
2218         if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2219                 return -EINVAL;
2220
2221         if (!set->ops->queue_rq)
2222                 return -EINVAL;
2223
2224         if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2225                 pr_info("blk-mq: reduced tag depth to %u\n",
2226                         BLK_MQ_MAX_DEPTH);
2227                 set->queue_depth = BLK_MQ_MAX_DEPTH;
2228         }
2229
2230         /*
2231          * If a crashdump is active, then we are potentially in a very
2232          * memory constrained environment. Limit us to 1 queue and
2233          * 64 tags to prevent using too much memory.
2234          */
2235         if (is_kdump_kernel()) {
2236                 set->nr_hw_queues = 1;
2237                 set->queue_depth = min(64U, set->queue_depth);
2238         }
2239         /*
2240          * There is no use for more h/w queues than cpus.
2241          */
2242         if (set->nr_hw_queues > nr_cpu_ids)
2243                 set->nr_hw_queues = nr_cpu_ids;
2244
2245         set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2246                                  GFP_KERNEL, set->numa_node);
2247         if (!set->tags)
2248                 return -ENOMEM;
2249
2250         ret = -ENOMEM;
2251         set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
2252                         GFP_KERNEL, set->numa_node);
2253         if (!set->mq_map)
2254                 goto out_free_tags;
2255
2256         if (set->ops->map_queues)
2257                 ret = set->ops->map_queues(set);
2258         else
2259                 ret = blk_mq_map_queues(set);
2260         if (ret)
2261                 goto out_free_mq_map;
2262
2263         ret = blk_mq_alloc_rq_maps(set);
2264         if (ret)
2265                 goto out_free_mq_map;
2266
2267         mutex_init(&set->tag_list_lock);
2268         INIT_LIST_HEAD(&set->tag_list);
2269
2270         return 0;
2271
2272 out_free_mq_map:
2273         kfree(set->mq_map);
2274         set->mq_map = NULL;
2275 out_free_tags:
2276         kfree(set->tags);
2277         set->tags = NULL;
2278         return ret;
2279 }
2280 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2281
2282 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2283 {
2284         int i;
2285
2286         for (i = 0; i < nr_cpu_ids; i++) {
2287                 if (set->tags[i])
2288                         blk_mq_free_rq_map(set, set->tags[i], i);
2289         }
2290
2291         kfree(set->mq_map);
2292         set->mq_map = NULL;
2293
2294         kfree(set->tags);
2295         set->tags = NULL;
2296 }
2297 EXPORT_SYMBOL(blk_mq_free_tag_set);
2298
2299 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2300 {
2301         struct blk_mq_tag_set *set = q->tag_set;
2302         struct blk_mq_hw_ctx *hctx;
2303         int i, ret;
2304
2305         if (!set || nr > set->queue_depth)
2306                 return -EINVAL;
2307
2308         ret = 0;
2309         queue_for_each_hw_ctx(q, hctx, i) {
2310                 if (!hctx->tags)
2311                         continue;
2312                 ret = blk_mq_tag_update_depth(hctx->tags, nr);
2313                 if (ret)
2314                         break;
2315         }
2316
2317         if (!ret)
2318                 q->nr_requests = nr;
2319
2320         return ret;
2321 }
2322
2323 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2324 {
2325         struct request_queue *q;
2326
2327         if (nr_hw_queues > nr_cpu_ids)
2328                 nr_hw_queues = nr_cpu_ids;
2329         if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2330                 return;
2331
2332         list_for_each_entry(q, &set->tag_list, tag_set_list)
2333                 blk_mq_freeze_queue(q);
2334
2335         set->nr_hw_queues = nr_hw_queues;
2336         list_for_each_entry(q, &set->tag_list, tag_set_list) {
2337                 blk_mq_realloc_hw_ctxs(set, q);
2338
2339                 if (q->nr_hw_queues > 1)
2340                         blk_queue_make_request(q, blk_mq_make_request);
2341                 else
2342                         blk_queue_make_request(q, blk_sq_make_request);
2343
2344                 blk_mq_queue_reinit(q, cpu_online_mask);
2345         }
2346
2347         list_for_each_entry(q, &set->tag_list, tag_set_list)
2348                 blk_mq_unfreeze_queue(q);
2349 }
2350 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2351
2352 void blk_mq_disable_hotplug(void)
2353 {
2354         mutex_lock(&all_q_mutex);
2355 }
2356
2357 void blk_mq_enable_hotplug(void)
2358 {
2359         mutex_unlock(&all_q_mutex);
2360 }
2361
2362 static int __init blk_mq_init(void)
2363 {
2364         cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
2365                                 blk_mq_hctx_notify_dead);
2366
2367         cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE, "block/mq:prepare",
2368                                   blk_mq_queue_reinit_prepare,
2369                                   blk_mq_queue_reinit_dead);
2370         return 0;
2371 }
2372 subsys_initcall(blk_mq_init);