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         swait_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                 swake_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         swake_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 #ifdef CONFIG_PREEMPT_RT_FULL
 181         INIT_WORK(&rq->work, __blk_mq_complete_request_remote_work);
 182 #endif
 183         INIT_LIST_HEAD(&rq->timeout_list);
 184         rq->timeout = 0;
 185
 186         rq->end_io = NULL;
 187         rq->end_io_data = NULL;
 188         rq->next_rq = NULL;
 189
 190         ctx->rq_dispatched[rw_is_sync(op, op_flags)]++;
 191 }
 192
 193 static struct request *
 194 __blk_mq_alloc_request(struct blk_mq_alloc_data *data, int op, int op_flags)
 195 {
 196         struct request *rq;
 197         unsigned int tag;
 198
 199         tag = blk_mq_get_tag(data);
 200         if (tag != BLK_MQ_TAG_FAIL) {
 201                 rq = data->hctx->tags->rqs[tag];
 202
 203                 if (blk_mq_tag_busy(data->hctx)) {
 204                         rq->cmd_flags = REQ_MQ_INFLIGHT;
 205                         atomic_inc(&data->hctx->nr_active);
 206                 }
 207
 208                 rq->tag = tag;
 209                 blk_mq_rq_ctx_init(data->q, data->ctx, rq, op, op_flags);
 210                 return rq;
 211         }
 212
 213         return NULL;
 214 }
 215
 216 struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
 217                 unsigned int flags)
 218 {
 219         struct blk_mq_ctx *ctx;
 220         struct blk_mq_hw_ctx *hctx;
 221         struct request *rq;
 222         struct blk_mq_alloc_data alloc_data;
 223         int ret;
 224
 225         ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
 226         if (ret)
 227                 return ERR_PTR(ret);
 228
 229         ctx = blk_mq_get_ctx(q);
 230         hctx = blk_mq_map_queue(q, ctx->cpu);
 231         blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
 232         rq = __blk_mq_alloc_request(&alloc_data, rw, 0);
 233         blk_mq_put_ctx(ctx);
 234
 235         if (!rq) {
 236                 blk_queue_exit(q);
 237                 return ERR_PTR(-EWOULDBLOCK);
 238         }
 239
 240         rq->__data_len = 0;
 241         rq->__sector = (sector_t) -1;
 242         rq->bio = rq->biotail = NULL;
 243         return rq;
 244 }
 245 EXPORT_SYMBOL(blk_mq_alloc_request);
 246
 247 struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
 248                 unsigned int flags, unsigned int hctx_idx)
 249 {
 250         struct blk_mq_hw_ctx *hctx;
 251         struct blk_mq_ctx *ctx;
 252         struct request *rq;
 253         struct blk_mq_alloc_data alloc_data;
 254         int ret;
 255
 256         /*
 257          * If the tag allocator sleeps we could get an allocation for a
 258          * different hardware context.  No need to complicate the low level
 259          * allocator for this for the rare use case of a command tied to
 260          * a specific queue.
 261          */
 262         if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
 263                 return ERR_PTR(-EINVAL);
 264
 265         if (hctx_idx >= q->nr_hw_queues)
 266                 return ERR_PTR(-EIO);
 267
 268         ret = blk_queue_enter(q, true);
 269         if (ret)
 270                 return ERR_PTR(ret);
 271
 272         /*
 273          * Check if the hardware context is actually mapped to anything.
 274          * If not tell the caller that it should skip this queue.
 275          */
 276         hctx = q->queue_hw_ctx[hctx_idx];
 277         if (!blk_mq_hw_queue_mapped(hctx)) {
 278                 ret = -EXDEV;
 279                 goto out_queue_exit;
 280         }
 281         ctx = __blk_mq_get_ctx(q, cpumask_first(hctx->cpumask));
 282
 283         blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
 284         rq = __blk_mq_alloc_request(&alloc_data, rw, 0);
 285         if (!rq) {
 286                 ret = -EWOULDBLOCK;
 287                 goto out_queue_exit;
 288         }
 289
 290         return rq;
 291
 292 out_queue_exit:
 293         blk_queue_exit(q);
 294         return ERR_PTR(ret);
 295 }
 296 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
 297
 298 static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
 299                                   struct blk_mq_ctx *ctx, struct request *rq)
 300 {
 301         const int tag = rq->tag;
 302         struct request_queue *q = rq->q;
 303
 304         if (rq->cmd_flags & REQ_MQ_INFLIGHT)
 305                 atomic_dec(&hctx->nr_active);
 306         rq->cmd_flags = 0;
 307
 308         clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 309         blk_mq_put_tag(hctx, ctx, tag);
 310         blk_queue_exit(q);
 311 }
 312
 313 void blk_mq_free_hctx_request(struct blk_mq_hw_ctx *hctx, struct request *rq)
 314 {
 315         struct blk_mq_ctx *ctx = rq->mq_ctx;
 316
 317         ctx->rq_completed[rq_is_sync(rq)]++;
 318         __blk_mq_free_request(hctx, ctx, rq);
 319
 320 }
 321 EXPORT_SYMBOL_GPL(blk_mq_free_hctx_request);
 322
 323 void blk_mq_free_request(struct request *rq)
 324 {
 325         blk_mq_free_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
 326 }
 327 EXPORT_SYMBOL_GPL(blk_mq_free_request);
 328
 329 inline void __blk_mq_end_request(struct request *rq, int error)
 330 {
 331         blk_account_io_done(rq);
 332
 333         if (rq->end_io) {
 334                 rq->end_io(rq, error);
 335         } else {
 336                 if (unlikely(blk_bidi_rq(rq)))
 337                         blk_mq_free_request(rq->next_rq);
 338                 blk_mq_free_request(rq);
 339         }
 340 }
 341 EXPORT_SYMBOL(__blk_mq_end_request);
 342
 343 void blk_mq_end_request(struct request *rq, int error)
 344 {
 345         if (blk_update_request(rq, error, blk_rq_bytes(rq)))
 346                 BUG();
 347         __blk_mq_end_request(rq, error);
 348 }
 349 EXPORT_SYMBOL(blk_mq_end_request);
 350
 351 #ifdef CONFIG_PREEMPT_RT_FULL
 352
 353 void __blk_mq_complete_request_remote_work(struct work_struct *work)
 354 {
 355         struct request *rq = container_of(work, struct request, work);
 356
 357         rq->q->softirq_done_fn(rq);
 358 }
 359
 360 #else
 361
 362 static void __blk_mq_complete_request_remote(void *data)
 363 {
 364         struct request *rq = data;
 365
 366         rq->q->softirq_done_fn(rq);
 367 }
 368
 369 #endif
 370
 371 static void blk_mq_ipi_complete_request(struct request *rq)
 372 {
 373         struct blk_mq_ctx *ctx = rq->mq_ctx;
 374         bool shared = false;
 375         int cpu;
 376
 377         if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
 378                 rq->q->softirq_done_fn(rq);
 379                 return;
 380         }
 381
 382         cpu = get_cpu_light();
 383         if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
 384                 shared = cpus_share_cache(cpu, ctx->cpu);
 385
 386         if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
 387 #ifdef CONFIG_PREEMPT_RT_FULL
 388                 schedule_work_on(ctx->cpu, &rq->work);
 389 #else
 390                 rq->csd.func = __blk_mq_complete_request_remote;
 391                 rq->csd.info = rq;
 392                 rq->csd.flags = 0;
 393                 smp_call_function_single_async(ctx->cpu, &rq->csd);
 394 #endif
 395         } else {
 396                 rq->q->softirq_done_fn(rq);
 397         }
 398         put_cpu_light();
 399 }
 400
 401 static void __blk_mq_complete_request(struct request *rq)
 402 {
 403         struct request_queue *q = rq->q;
 404
 405         if (!q->softirq_done_fn)
 406                 blk_mq_end_request(rq, rq->errors);
 407         else
 408                 blk_mq_ipi_complete_request(rq);
 409 }
 410
 411 /**
 412  * blk_mq_complete_request - end I/O on a request
 413  * @rq:         the request being processed
 414  *
 415  * Description:
 416  *      Ends all I/O on a request. It does not handle partial completions.
 417  *      The actual completion happens out-of-order, through a IPI handler.
 418  **/
 419 void blk_mq_complete_request(struct request *rq, int error)
 420 {
 421         struct request_queue *q = rq->q;
 422
 423         if (unlikely(blk_should_fake_timeout(q)))
 424                 return;
 425         if (!blk_mark_rq_complete(rq)) {
 426                 rq->errors = error;
 427                 __blk_mq_complete_request(rq);
 428         }
 429 }
 430 EXPORT_SYMBOL(blk_mq_complete_request);
 431
 432 int blk_mq_request_started(struct request *rq)
 433 {
 434         return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 435 }
 436 EXPORT_SYMBOL_GPL(blk_mq_request_started);
 437
 438 void blk_mq_start_request(struct request *rq)
 439 {
 440         struct request_queue *q = rq->q;
 441
 442         trace_block_rq_issue(q, rq);
 443
 444         rq->resid_len = blk_rq_bytes(rq);
 445         if (unlikely(blk_bidi_rq(rq)))
 446                 rq->next_rq->resid_len = blk_rq_bytes(rq->next_rq);
 447
 448         blk_add_timer(rq);
 449
 450         /*
 451          * Ensure that ->deadline is visible before set the started
 452          * flag and clear the completed flag.
 453          */
 454         smp_mb__before_atomic();
 455
 456         /*
 457          * Mark us as started and clear complete. Complete might have been
 458          * set if requeue raced with timeout, which then marked it as
 459          * complete. So be sure to clear complete again when we start
 460          * the request, otherwise we'll ignore the completion event.
 461          */
 462         if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
 463                 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 464         if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
 465                 clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
 466
 467         if (q->dma_drain_size && blk_rq_bytes(rq)) {
 468                 /*
 469                  * Make sure space for the drain appears.  We know we can do
 470                  * this because max_hw_segments has been adjusted to be one
 471                  * fewer than the device can handle.
 472                  */
 473                 rq->nr_phys_segments++;
 474         }
 475 }
 476 EXPORT_SYMBOL(blk_mq_start_request);
 477
 478 static void __blk_mq_requeue_request(struct request *rq)
 479 {
 480         struct request_queue *q = rq->q;
 481
 482         trace_block_rq_requeue(q, rq);
 483
 484         if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
 485                 if (q->dma_drain_size && blk_rq_bytes(rq))
 486                         rq->nr_phys_segments--;
 487         }
 488 }
 489
 490 void blk_mq_requeue_request(struct request *rq)
 491 {
 492         __blk_mq_requeue_request(rq);
 493
 494         BUG_ON(blk_queued_rq(rq));
 495         blk_mq_add_to_requeue_list(rq, true);
 496 }
 497 EXPORT_SYMBOL(blk_mq_requeue_request);
 498
 499 static void blk_mq_requeue_work(struct work_struct *work)
 500 {
 501         struct request_queue *q =
 502                 container_of(work, struct request_queue, requeue_work.work);
 503         LIST_HEAD(rq_list);
 504         struct request *rq, *next;
 505         unsigned long flags;
 506
 507         spin_lock_irqsave(&q->requeue_lock, flags);
 508         list_splice_init(&q->requeue_list, &rq_list);
 509         spin_unlock_irqrestore(&q->requeue_lock, flags);
 510
 511         list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
 512                 if (!(rq->cmd_flags & REQ_SOFTBARRIER))
 513                         continue;
 514
 515                 rq->cmd_flags &= ~REQ_SOFTBARRIER;
 516                 list_del_init(&rq->queuelist);
 517                 blk_mq_insert_request(rq, true, false, false);
 518         }
 519
 520         while (!list_empty(&rq_list)) {
 521                 rq = list_entry(rq_list.next, struct request, queuelist);
 522                 list_del_init(&rq->queuelist);
 523                 blk_mq_insert_request(rq, false, false, false);
 524         }
 525
 526         /*
 527          * Use the start variant of queue running here, so that running
 528          * the requeue work will kick stopped queues.
 529          */
 530         blk_mq_start_hw_queues(q);
 531 }
 532
 533 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head)
 534 {
 535         struct request_queue *q = rq->q;
 536         unsigned long flags;
 537
 538         /*
 539          * We abuse this flag that is otherwise used by the I/O scheduler to
 540          * request head insertation from the workqueue.
 541          */
 542         BUG_ON(rq->cmd_flags & REQ_SOFTBARRIER);
 543
 544         spin_lock_irqsave(&q->requeue_lock, flags);
 545         if (at_head) {
 546                 rq->cmd_flags |= REQ_SOFTBARRIER;
 547                 list_add(&rq->queuelist, &q->requeue_list);
 548         } else {
 549                 list_add_tail(&rq->queuelist, &q->requeue_list);
 550         }
 551         spin_unlock_irqrestore(&q->requeue_lock, flags);
 552 }
 553 EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
 554
 555 void blk_mq_cancel_requeue_work(struct request_queue *q)
 556 {
 557         cancel_delayed_work_sync(&q->requeue_work);
 558 }
 559 EXPORT_SYMBOL_GPL(blk_mq_cancel_requeue_work);
 560
 561 void blk_mq_kick_requeue_list(struct request_queue *q)
 562 {
 563         kblockd_schedule_delayed_work(&q->requeue_work, 0);
 564 }
 565 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
 566
 567 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
 568                                     unsigned long msecs)
 569 {
 570         kblockd_schedule_delayed_work(&q->requeue_work,
 571                                       msecs_to_jiffies(msecs));
 572 }
 573 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
 574
 575 void blk_mq_abort_requeue_list(struct request_queue *q)
 576 {
 577         unsigned long flags;
 578         LIST_HEAD(rq_list);
 579
 580         spin_lock_irqsave(&q->requeue_lock, flags);
 581         list_splice_init(&q->requeue_list, &rq_list);
 582         spin_unlock_irqrestore(&q->requeue_lock, flags);
 583
 584         while (!list_empty(&rq_list)) {
 585                 struct request *rq;
 586
 587                 rq = list_first_entry(&rq_list, struct request, queuelist);
 588                 list_del_init(&rq->queuelist);
 589                 rq->errors = -EIO;
 590                 blk_mq_end_request(rq, rq->errors);
 591         }
 592 }
 593 EXPORT_SYMBOL(blk_mq_abort_requeue_list);
 594
 595 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
 596 {
 597         if (tag < tags->nr_tags) {
 598                 prefetch(tags->rqs[tag]);
 599                 return tags->rqs[tag];
 600         }
 601
 602         return NULL;
 603 }
 604 EXPORT_SYMBOL(blk_mq_tag_to_rq);
 605
 606 struct blk_mq_timeout_data {
 607         unsigned long next;
 608         unsigned int next_set;
 609 };
 610
 611 void blk_mq_rq_timed_out(struct request *req, bool reserved)
 612 {
 613         struct blk_mq_ops *ops = req->q->mq_ops;
 614         enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
 615
 616         /*
 617          * We know that complete is set at this point. If STARTED isn't set
 618          * anymore, then the request isn't active and the "timeout" should
 619          * just be ignored. This can happen due to the bitflag ordering.
 620          * Timeout first checks if STARTED is set, and if it is, assumes
 621          * the request is active. But if we race with completion, then
 622          * we both flags will get cleared. So check here again, and ignore
 623          * a timeout event with a request that isn't active.
 624          */
 625         if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
 626                 return;
 627
 628         if (ops->timeout)
 629                 ret = ops->timeout(req, reserved);
 630
 631         switch (ret) {
 632         case BLK_EH_HANDLED:
 633                 __blk_mq_complete_request(req);
 634                 break;
 635         case BLK_EH_RESET_TIMER:
 636                 blk_add_timer(req);
 637                 blk_clear_rq_complete(req);
 638                 break;
 639         case BLK_EH_NOT_HANDLED:
 640                 break;
 641         default:
 642                 printk(KERN_ERR "block: bad eh return: %d\n", ret);
 643                 break;
 644         }
 645 }
 646
 647 static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
 648                 struct request *rq, void *priv, bool reserved)
 649 {
 650         struct blk_mq_timeout_data *data = priv;
 651
 652         if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
 653                 /*
 654                  * If a request wasn't started before the queue was
 655                  * marked dying, kill it here or it'll go unnoticed.
 656                  */
 657                 if (unlikely(blk_queue_dying(rq->q))) {
 658                         rq->errors = -EIO;
 659                         blk_mq_end_request(rq, rq->errors);
 660                 }
 661                 return;
 662         }
 663
 664         if (time_after_eq(jiffies, rq->deadline)) {
 665                 if (!blk_mark_rq_complete(rq))
 666                         blk_mq_rq_timed_out(rq, reserved);
 667         } else if (!data->next_set || time_after(data->next, rq->deadline)) {
 668                 data->next = rq->deadline;
 669                 data->next_set = 1;
 670         }
 671 }
 672
 673 static void blk_mq_timeout_work(struct work_struct *work)
 674 {
 675         struct request_queue *q =
 676                 container_of(work, struct request_queue, timeout_work);
 677         struct blk_mq_timeout_data data = {
 678                 .next           = 0,
 679                 .next_set       = 0,
 680         };
 681         int i;
 682
 683         /* A deadlock might occur if a request is stuck requiring a
 684          * timeout at the same time a queue freeze is waiting
 685          * completion, since the timeout code would not be able to
 686          * acquire the queue reference here.
 687          *
 688          * That's why we don't use blk_queue_enter here; instead, we use
 689          * percpu_ref_tryget directly, because we need to be able to
 690          * obtain a reference even in the short window between the queue
 691          * starting to freeze, by dropping the first reference in
 692          * blk_mq_freeze_queue_start, and the moment the last request is
 693          * consumed, marked by the instant q_usage_counter reaches
 694          * zero.
 695          */
 696         if (!percpu_ref_tryget(&q->q_usage_counter))
 697                 return;
 698
 699         blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
 700
 701         if (data.next_set) {
 702                 data.next = blk_rq_timeout(round_jiffies_up(data.next));
 703                 mod_timer(&q->timeout, data.next);
 704         } else {
 705                 struct blk_mq_hw_ctx *hctx;
 706
 707                 queue_for_each_hw_ctx(q, hctx, i) {
 708                         /* the hctx may be unmapped, so check it here */
 709                         if (blk_mq_hw_queue_mapped(hctx))
 710                                 blk_mq_tag_idle(hctx);
 711                 }
 712         }
 713         blk_queue_exit(q);
 714 }
 715
 716 /*
 717  * Reverse check our software queue for entries that we could potentially
 718  * merge with. Currently includes a hand-wavy stop count of 8, to not spend
 719  * too much time checking for merges.
 720  */
 721 static bool blk_mq_attempt_merge(struct request_queue *q,
 722                                  struct blk_mq_ctx *ctx, struct bio *bio)
 723 {
 724         struct request *rq;
 725         int checked = 8;
 726
 727         list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
 728                 int el_ret;
 729
 730                 if (!checked--)
 731                         break;
 732
 733                 if (!blk_rq_merge_ok(rq, bio))
 734                         continue;
 735
 736                 el_ret = blk_try_merge(rq, bio);
 737                 if (el_ret == ELEVATOR_BACK_MERGE) {
 738                         if (bio_attempt_back_merge(q, rq, bio)) {
 739                                 ctx->rq_merged++;
 740                                 return true;
 741                         }
 742                         break;
 743                 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
 744                         if (bio_attempt_front_merge(q, rq, bio)) {
 745                                 ctx->rq_merged++;
 746                                 return true;
 747                         }
 748                         break;
 749                 }
 750         }
 751
 752         return false;
 753 }
 754
 755 struct flush_busy_ctx_data {
 756         struct blk_mq_hw_ctx *hctx;
 757         struct list_head *list;
 758 };
 759
 760 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
 761 {
 762         struct flush_busy_ctx_data *flush_data = data;
 763         struct blk_mq_hw_ctx *hctx = flush_data->hctx;
 764         struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
 765
 766         sbitmap_clear_bit(sb, bitnr);
 767         spin_lock(&ctx->lock);
 768         list_splice_tail_init(&ctx->rq_list, flush_data->list);
 769         spin_unlock(&ctx->lock);
 770         return true;
 771 }
 772
 773 /*
 774  * Process software queues that have been marked busy, splicing them
 775  * to the for-dispatch
 776  */
 777 static void flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
 778 {
 779         struct flush_busy_ctx_data data = {
 780                 .hctx = hctx,
 781                 .list = list,
 782         };
 783
 784         sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
 785 }
 786
 787 static inline unsigned int queued_to_index(unsigned int queued)
 788 {
 789         if (!queued)
 790                 return 0;
 791
 792         return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
 793 }
 794
 795 /*
 796  * Run this hardware queue, pulling any software queues mapped to it in.
 797  * Note that this function currently has various problems around ordering
 798  * of IO. In particular, we'd like FIFO behaviour on handling existing
 799  * items on the hctx->dispatch list. Ignore that for now.
 800  */
 801 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
 802 {
 803         struct request_queue *q = hctx->queue;
 804         struct request *rq;
 805         LIST_HEAD(rq_list);
 806         LIST_HEAD(driver_list);
 807         struct list_head *dptr;
 808         int queued;
 809
 810         if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
 811                 return;
 812
 813         WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
 814                 cpu_online(hctx->next_cpu));
 815
 816         hctx->run++;
 817
 818         /*
 819          * Touch any software queue that has pending entries.
 820          */
 821         flush_busy_ctxs(hctx, &rq_list);
 822
 823         /*
 824          * If we have previous entries on our dispatch list, grab them
 825          * and stuff them at the front for more fair dispatch.
 826          */
 827         if (!list_empty_careful(&hctx->dispatch)) {
 828                 spin_lock(&hctx->lock);
 829                 if (!list_empty(&hctx->dispatch))
 830                         list_splice_init(&hctx->dispatch, &rq_list);
 831                 spin_unlock(&hctx->lock);
 832         }
 833
 834         /*
 835          * Start off with dptr being NULL, so we start the first request
 836          * immediately, even if we have more pending.
 837          */
 838         dptr = NULL;
 839
 840         /*
 841          * Now process all the entries, sending them to the driver.
 842          */
 843         queued = 0;
 844         while (!list_empty(&rq_list)) {
 845                 struct blk_mq_queue_data bd;
 846                 int ret;
 847
 848                 rq = list_first_entry(&rq_list, struct request, queuelist);
 849                 list_del_init(&rq->queuelist);
 850
 851                 bd.rq = rq;
 852                 bd.list = dptr;
 853                 bd.last = list_empty(&rq_list);
 854
 855                 ret = q->mq_ops->queue_rq(hctx, &bd);
 856                 switch (ret) {
 857                 case BLK_MQ_RQ_QUEUE_OK:
 858                         queued++;
 859                         break;
 860                 case BLK_MQ_RQ_QUEUE_BUSY:
 861                         list_add(&rq->queuelist, &rq_list);
 862                         __blk_mq_requeue_request(rq);
 863                         break;
 864                 default:
 865                         pr_err("blk-mq: bad return on queue: %d\n", ret);
 866                 case BLK_MQ_RQ_QUEUE_ERROR:
 867                         rq->errors = -EIO;
 868                         blk_mq_end_request(rq, rq->errors);
 869                         break;
 870                 }
 871
 872                 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
 873                         break;
 874
 875                 /*
 876                  * We've done the first request. If we have more than 1
 877                  * left in the list, set dptr to defer issue.
 878                  */
 879                 if (!dptr && rq_list.next != rq_list.prev)
 880                         dptr = &driver_list;
 881         }
 882
 883         hctx->dispatched[queued_to_index(queued)]++;
 884
 885         /*
 886          * Any items that need requeuing? Stuff them into hctx->dispatch,
 887          * that is where we will continue on next queue run.
 888          */
 889         if (!list_empty(&rq_list)) {
 890                 spin_lock(&hctx->lock);
 891                 list_splice(&rq_list, &hctx->dispatch);
 892                 spin_unlock(&hctx->lock);
 893                 /*
 894                  * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
 895                  * it's possible the queue is stopped and restarted again
 896                  * before this. Queue restart will dispatch requests. And since
 897                  * requests in rq_list aren't added into hctx->dispatch yet,
 898                  * the requests in rq_list might get lost.
 899                  *
 900                  * blk_mq_run_hw_queue() already checks the STOPPED bit
 901                  **/
 902                 blk_mq_run_hw_queue(hctx, true);
 903         }
 904 }
 905
 906 /*
 907  * It'd be great if the workqueue API had a way to pass
 908  * in a mask and had some smarts for more clever placement.
 909  * For now we just round-robin here, switching for every
 910  * BLK_MQ_CPU_WORK_BATCH queued items.
 911  */
 912 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
 913 {
 914         if (hctx->queue->nr_hw_queues == 1)
 915                 return WORK_CPU_UNBOUND;
 916
 917         if (--hctx->next_cpu_batch <= 0) {
 918                 int cpu = hctx->next_cpu, next_cpu;
 919
 920                 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
 921                 if (next_cpu >= nr_cpu_ids)
 922                         next_cpu = cpumask_first(hctx->cpumask);
 923
 924                 hctx->next_cpu = next_cpu;
 925                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
 926
 927                 return cpu;
 928         }
 929
 930         return hctx->next_cpu;
 931 }
 932
 933 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
 934 {
 935         if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state) ||
 936             !blk_mq_hw_queue_mapped(hctx)))
 937                 return;
 938
 939         if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
 940                 int cpu = get_cpu_light();
 941                 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
 942                         __blk_mq_run_hw_queue(hctx);
 943                         put_cpu_light();
 944                         return;
 945                 }
 946
 947                 put_cpu_light();
 948         }
 949
 950         kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work);
 951 }
 952
 953 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
 954 {
 955         struct blk_mq_hw_ctx *hctx;
 956         int i;
 957
 958         queue_for_each_hw_ctx(q, hctx, i) {
 959                 if ((!blk_mq_hctx_has_pending(hctx) &&
 960                     list_empty_careful(&hctx->dispatch)) ||
 961                     test_bit(BLK_MQ_S_STOPPED, &hctx->state))
 962                         continue;
 963
 964                 blk_mq_run_hw_queue(hctx, async);
 965         }
 966 }
 967 EXPORT_SYMBOL(blk_mq_run_hw_queues);
 968
 969 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
 970 {
 971         cancel_work(&hctx->run_work);
 972         cancel_delayed_work(&hctx->delay_work);
 973         set_bit(BLK_MQ_S_STOPPED, &hctx->state);
 974 }
 975 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
 976
 977 void blk_mq_stop_hw_queues(struct request_queue *q)
 978 {
 979         struct blk_mq_hw_ctx *hctx;
 980         int i;
 981
 982         queue_for_each_hw_ctx(q, hctx, i)
 983                 blk_mq_stop_hw_queue(hctx);
 984 }
 985 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
 986
 987 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
 988 {
 989         clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
 990
 991         blk_mq_run_hw_queue(hctx, false);
 992 }
 993 EXPORT_SYMBOL(blk_mq_start_hw_queue);
 994
 995 void blk_mq_start_hw_queues(struct request_queue *q)
 996 {
 997         struct blk_mq_hw_ctx *hctx;
 998         int i;
 999
1000         queue_for_each_hw_ctx(q, hctx, i)
1001                 blk_mq_start_hw_queue(hctx);
1002 }
1003 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1004
1005 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1006 {
1007         struct blk_mq_hw_ctx *hctx;
1008         int i;
1009
1010         queue_for_each_hw_ctx(q, hctx, i) {
1011                 if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
1012                         continue;
1013
1014                 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1015                 blk_mq_run_hw_queue(hctx, async);
1016         }
1017 }
1018 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1019
1020 static void blk_mq_run_work_fn(struct work_struct *work)
1021 {
1022         struct blk_mq_hw_ctx *hctx;
1023
1024         hctx = container_of(work, struct blk_mq_hw_ctx, run_work);
1025
1026         __blk_mq_run_hw_queue(hctx);
1027 }
1028
1029 static void blk_mq_delay_work_fn(struct work_struct *work)
1030 {
1031         struct blk_mq_hw_ctx *hctx;
1032
1033         hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
1034
1035         if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
1036                 __blk_mq_run_hw_queue(hctx);
1037 }
1038
1039 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1040 {
1041         if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
1042                 return;
1043
1044         kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1045                         &hctx->delay_work, msecs_to_jiffies(msecs));
1046 }
1047 EXPORT_SYMBOL(blk_mq_delay_queue);
1048
1049 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1050                                             struct request *rq,
1051                                             bool at_head)
1052 {
1053         struct blk_mq_ctx *ctx = rq->mq_ctx;
1054
1055         trace_block_rq_insert(hctx->queue, rq);
1056
1057         if (at_head)
1058                 list_add(&rq->queuelist, &ctx->rq_list);
1059         else
1060                 list_add_tail(&rq->queuelist, &ctx->rq_list);
1061 }
1062
1063 static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
1064                                     struct request *rq, bool at_head)
1065 {
1066         struct blk_mq_ctx *ctx = rq->mq_ctx;
1067
1068         __blk_mq_insert_req_list(hctx, rq, at_head);
1069         blk_mq_hctx_mark_pending(hctx, ctx);
1070 }
1071
1072 void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
1073                            bool async)
1074 {
1075         struct blk_mq_ctx *ctx = rq->mq_ctx;
1076         struct request_queue *q = rq->q;
1077         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
1078
1079         spin_lock(&ctx->lock);
1080         __blk_mq_insert_request(hctx, rq, at_head);
1081         spin_unlock(&ctx->lock);
1082
1083         if (run_queue)
1084                 blk_mq_run_hw_queue(hctx, async);
1085 }
1086
1087 static void blk_mq_insert_requests(struct request_queue *q,
1088                                      struct blk_mq_ctx *ctx,
1089                                      struct list_head *list,
1090                                      int depth,
1091                                      bool from_schedule)
1092
1093 {
1094         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
1095
1096         trace_block_unplug(q, depth, !from_schedule);
1097
1098         /*
1099          * preemption doesn't flush plug list, so it's possible ctx->cpu is
1100          * offline now
1101          */
1102         spin_lock(&ctx->lock);
1103         while (!list_empty(list)) {
1104                 struct request *rq;
1105
1106                 rq = list_first_entry(list, struct request, queuelist);
1107                 BUG_ON(rq->mq_ctx != ctx);
1108                 list_del_init(&rq->queuelist);
1109                 __blk_mq_insert_req_list(hctx, rq, false);
1110         }
1111         blk_mq_hctx_mark_pending(hctx, ctx);
1112         spin_unlock(&ctx->lock);
1113
1114         blk_mq_run_hw_queue(hctx, from_schedule);
1115 }
1116
1117 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1118 {
1119         struct request *rqa = container_of(a, struct request, queuelist);
1120         struct request *rqb = container_of(b, struct request, queuelist);
1121
1122         return !(rqa->mq_ctx < rqb->mq_ctx ||
1123                  (rqa->mq_ctx == rqb->mq_ctx &&
1124                   blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1125 }
1126
1127 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1128 {
1129         struct blk_mq_ctx *this_ctx;
1130         struct request_queue *this_q;
1131         struct request *rq;
1132         LIST_HEAD(list);
1133         LIST_HEAD(ctx_list);
1134         unsigned int depth;
1135
1136         list_splice_init(&plug->mq_list, &list);
1137
1138         list_sort(NULL, &list, plug_ctx_cmp);
1139
1140         this_q = NULL;
1141         this_ctx = NULL;
1142         depth = 0;
1143
1144         while (!list_empty(&list)) {
1145                 rq = list_entry_rq(list.next);
1146                 list_del_init(&rq->queuelist);
1147                 BUG_ON(!rq->q);
1148                 if (rq->mq_ctx != this_ctx) {
1149                         if (this_ctx) {
1150                                 blk_mq_insert_requests(this_q, this_ctx,
1151                                                         &ctx_list, depth,
1152                                                         from_schedule);
1153                         }
1154
1155                         this_ctx = rq->mq_ctx;
1156                         this_q = rq->q;
1157                         depth = 0;
1158                 }
1159
1160                 depth++;
1161                 list_add_tail(&rq->queuelist, &ctx_list);
1162         }
1163
1164         /*
1165          * If 'this_ctx' is set, we know we have entries to complete
1166          * on 'ctx_list'. Do those.
1167          */
1168         if (this_ctx) {
1169                 blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
1170                                        from_schedule);
1171         }
1172 }
1173
1174 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1175 {
1176         init_request_from_bio(rq, bio);
1177
1178         blk_account_io_start(rq, 1);
1179 }
1180
1181 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
1182 {
1183         return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
1184                 !blk_queue_nomerges(hctx->queue);
1185 }
1186
1187 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
1188                                          struct blk_mq_ctx *ctx,
1189                                          struct request *rq, struct bio *bio)
1190 {
1191         if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
1192                 blk_mq_bio_to_request(rq, bio);
1193                 spin_lock(&ctx->lock);
1194 insert_rq:
1195                 __blk_mq_insert_request(hctx, rq, false);
1196                 spin_unlock(&ctx->lock);
1197                 return false;
1198         } else {
1199                 struct request_queue *q = hctx->queue;
1200
1201                 spin_lock(&ctx->lock);
1202                 if (!blk_mq_attempt_merge(q, ctx, bio)) {
1203                         blk_mq_bio_to_request(rq, bio);
1204                         goto insert_rq;
1205                 }
1206
1207                 spin_unlock(&ctx->lock);
1208                 __blk_mq_free_request(hctx, ctx, rq);
1209                 return true;
1210         }
1211 }
1212
1213 struct blk_map_ctx {
1214         struct blk_mq_hw_ctx *hctx;
1215         struct blk_mq_ctx *ctx;
1216 };
1217
1218 static struct request *blk_mq_map_request(struct request_queue *q,
1219                                           struct bio *bio,
1220                                           struct blk_map_ctx *data)
1221 {
1222         struct blk_mq_hw_ctx *hctx;
1223         struct blk_mq_ctx *ctx;
1224         struct request *rq;
1225         int op = bio_data_dir(bio);
1226         int op_flags = 0;
1227         struct blk_mq_alloc_data alloc_data;
1228
1229         blk_queue_enter_live(q);
1230         ctx = blk_mq_get_ctx(q);
1231         hctx = blk_mq_map_queue(q, ctx->cpu);
1232
1233         if (rw_is_sync(bio_op(bio), bio->bi_opf))
1234                 op_flags |= REQ_SYNC;
1235
1236         trace_block_getrq(q, bio, op);
1237         blk_mq_set_alloc_data(&alloc_data, q, 0, ctx, hctx);
1238         rq = __blk_mq_alloc_request(&alloc_data, op, op_flags);
1239
1240         data->hctx = alloc_data.hctx;
1241         data->ctx = alloc_data.ctx;
1242         data->hctx->queued++;
1243         return rq;
1244 }
1245
1246 static int blk_mq_direct_issue_request(struct request *rq, blk_qc_t *cookie)
1247 {
1248         int ret;
1249         struct request_queue *q = rq->q;
1250         struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu);
1251         struct blk_mq_queue_data bd = {
1252                 .rq = rq,
1253                 .list = NULL,
1254                 .last = 1
1255         };
1256         blk_qc_t new_cookie = blk_tag_to_qc_t(rq->tag, hctx->queue_num);
1257
1258         /*
1259          * For OK queue, we are done. For error, kill it. Any other
1260          * error (busy), just add it to our list as we previously
1261          * would have done
1262          */
1263         ret = q->mq_ops->queue_rq(hctx, &bd);
1264         if (ret == BLK_MQ_RQ_QUEUE_OK) {
1265                 *cookie = new_cookie;
1266                 return 0;
1267         }
1268
1269         __blk_mq_requeue_request(rq);
1270
1271         if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
1272                 *cookie = BLK_QC_T_NONE;
1273                 rq->errors = -EIO;
1274                 blk_mq_end_request(rq, rq->errors);
1275                 return 0;
1276         }
1277
1278         return -1;
1279 }
1280
1281 /*
1282  * Multiple hardware queue variant. This will not use per-process plugs,
1283  * but will attempt to bypass the hctx queueing if we can go straight to
1284  * hardware for SYNC IO.
1285  */
1286 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1287 {
1288         const int is_sync = rw_is_sync(bio_op(bio), bio->bi_opf);
1289         const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
1290         struct blk_map_ctx data;
1291         struct request *rq;
1292         unsigned int request_count = 0;
1293         struct blk_plug *plug;
1294         struct request *same_queue_rq = NULL;
1295         blk_qc_t cookie;
1296
1297         blk_queue_bounce(q, &bio);
1298
1299         if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1300                 bio_io_error(bio);
1301                 return BLK_QC_T_NONE;
1302         }
1303
1304         blk_queue_split(q, &bio, q->bio_split);
1305
1306         if (!is_flush_fua && !blk_queue_nomerges(q) &&
1307             blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1308                 return BLK_QC_T_NONE;
1309
1310         rq = blk_mq_map_request(q, bio, &data);
1311         if (unlikely(!rq))
1312                 return BLK_QC_T_NONE;
1313
1314         cookie = blk_tag_to_qc_t(rq->tag, data.hctx->queue_num);
1315
1316         if (unlikely(is_flush_fua)) {
1317                 blk_mq_bio_to_request(rq, bio);
1318                 blk_insert_flush(rq);
1319                 goto run_queue;
1320         }
1321
1322         plug = current->plug;
1323         /*
1324          * If the driver supports defer issued based on 'last', then
1325          * queue it up like normal since we can potentially save some
1326          * CPU this way.
1327          */
1328         if (((plug && !blk_queue_nomerges(q)) || is_sync) &&
1329             !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
1330                 struct request *old_rq = NULL;
1331
1332                 blk_mq_bio_to_request(rq, bio);
1333
1334                 /*
1335                  * We do limited pluging. If the bio can be merged, do that.
1336                  * Otherwise the existing request in the plug list will be
1337                  * issued. So the plug list will have one request at most
1338                  */
1339                 if (plug) {
1340                         /*
1341                          * The plug list might get flushed before this. If that
1342                          * happens, same_queue_rq is invalid and plug list is
1343                          * empty
1344                          */
1345                         if (same_queue_rq && !list_empty(&plug->mq_list)) {
1346                                 old_rq = same_queue_rq;
1347                                 list_del_init(&old_rq->queuelist);
1348                         }
1349                         list_add_tail(&rq->queuelist, &plug->mq_list);
1350                 } else /* is_sync */
1351                         old_rq = rq;
1352                 blk_mq_put_ctx(data.ctx);
1353                 if (!old_rq)
1354                         goto done;
1355                 if (!blk_mq_direct_issue_request(old_rq, &cookie))
1356                         goto done;
1357                 blk_mq_insert_request(old_rq, false, true, true);
1358                 goto done;
1359         }
1360
1361         if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1362                 /*
1363                  * For a SYNC request, send it to the hardware immediately. For
1364                  * an ASYNC request, just ensure that we run it later on. The
1365                  * latter allows for merging opportunities and more efficient
1366                  * dispatching.
1367                  */
1368 run_queue:
1369                 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1370         }
1371         blk_mq_put_ctx(data.ctx);
1372 done:
1373         return cookie;
1374 }
1375
1376 /*
1377  * Single hardware queue variant. This will attempt to use any per-process
1378  * plug for merging and IO deferral.
1379  */
1380 static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
1381 {
1382         const int is_sync = rw_is_sync(bio_op(bio), bio->bi_opf);
1383         const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
1384         struct blk_plug *plug;
1385         unsigned int request_count = 0;
1386         struct blk_map_ctx data;
1387         struct request *rq;
1388         blk_qc_t cookie;
1389
1390         blk_queue_bounce(q, &bio);
1391
1392         if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1393                 bio_io_error(bio);
1394                 return BLK_QC_T_NONE;
1395         }
1396
1397         blk_queue_split(q, &bio, q->bio_split);
1398
1399         if (!is_flush_fua && !blk_queue_nomerges(q)) {
1400                 if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
1401                         return BLK_QC_T_NONE;
1402         } else
1403                 request_count = blk_plug_queued_count(q);
1404
1405         rq = blk_mq_map_request(q, bio, &data);
1406         if (unlikely(!rq))
1407                 return BLK_QC_T_NONE;
1408
1409         cookie = blk_tag_to_qc_t(rq->tag, data.hctx->queue_num);
1410
1411         if (unlikely(is_flush_fua)) {
1412                 blk_mq_bio_to_request(rq, bio);
1413                 blk_insert_flush(rq);
1414                 goto run_queue;
1415         }
1416
1417         /*
1418          * A task plug currently exists. Since this is completely lockless,
1419          * utilize that to temporarily store requests until the task is
1420          * either done or scheduled away.
1421          */
1422         plug = current->plug;
1423         if (plug) {
1424                 blk_mq_bio_to_request(rq, bio);
1425                 if (!request_count)
1426                         trace_block_plug(q);
1427
1428                 blk_mq_put_ctx(data.ctx);
1429
1430                 if (request_count >= BLK_MAX_REQUEST_COUNT) {
1431                         blk_flush_plug_list(plug, false);
1432                         trace_block_plug(q);
1433                 }
1434
1435                 list_add_tail(&rq->queuelist, &plug->mq_list);
1436                 return cookie;
1437         }
1438
1439         if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
1440                 /*
1441                  * For a SYNC request, send it to the hardware immediately. For
1442                  * an ASYNC request, just ensure that we run it later on. The
1443                  * latter allows for merging opportunities and more efficient
1444                  * dispatching.
1445                  */
1446 run_queue:
1447                 blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
1448         }
1449
1450         blk_mq_put_ctx(data.ctx);
1451         return cookie;
1452 }
1453
1454 static void blk_mq_free_rq_map(struct blk_mq_tag_set *set,
1455                 struct blk_mq_tags *tags, unsigned int hctx_idx)
1456 {
1457         struct page *page;
1458
1459         if (tags->rqs && set->ops->exit_request) {
1460                 int i;
1461
1462                 for (i = 0; i < tags->nr_tags; i++) {
1463                         if (!tags->rqs[i])
1464                                 continue;
1465                         set->ops->exit_request(set->driver_data, tags->rqs[i],
1466                                                 hctx_idx, i);
1467                         tags->rqs[i] = NULL;
1468                 }
1469         }
1470
1471         while (!list_empty(&tags->page_list)) {
1472                 page = list_first_entry(&tags->page_list, struct page, lru);
1473                 list_del_init(&page->lru);
1474                 /*
1475                  * Remove kmemleak object previously allocated in
1476                  * blk_mq_init_rq_map().
1477                  */
1478                 kmemleak_free(page_address(page));
1479                 __free_pages(page, page->private);
1480         }
1481
1482         kfree(tags->rqs);
1483
1484         blk_mq_free_tags(tags);
1485 }
1486
1487 static size_t order_to_size(unsigned int order)
1488 {
1489         return (size_t)PAGE_SIZE << order;
1490 }
1491
1492 static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
1493                 unsigned int hctx_idx)
1494 {
1495         struct blk_mq_tags *tags;
1496         unsigned int i, j, entries_per_page, max_order = 4;
1497         size_t rq_size, left;
1498
1499         tags = blk_mq_init_tags(set->queue_depth, set->reserved_tags,
1500                                 set->numa_node,
1501                                 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1502         if (!tags)
1503                 return NULL;
1504
1505         INIT_LIST_HEAD(&tags->page_list);
1506
1507         tags->rqs = kzalloc_node(set->queue_depth * sizeof(struct request *),
1508                                  GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
1509                                  set->numa_node);
1510         if (!tags->rqs) {
1511                 blk_mq_free_tags(tags);
1512                 return NULL;
1513         }
1514
1515         /*
1516          * rq_size is the size of the request plus driver payload, rounded
1517          * to the cacheline size
1518          */
1519         rq_size = round_up(sizeof(struct request) + set->cmd_size,
1520                                 cache_line_size());
1521         left = rq_size * set->queue_depth;
1522
1523         for (i = 0; i < set->queue_depth; ) {
1524                 int this_order = max_order;
1525                 struct page *page;
1526                 int to_do;
1527                 void *p;
1528
1529                 while (this_order && left < order_to_size(this_order - 1))
1530                         this_order--;
1531
1532                 do {
1533                         page = alloc_pages_node(set->numa_node,
1534                                 GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
1535                                 this_order);
1536                         if (page)
1537                                 break;
1538                         if (!this_order--)
1539                                 break;
1540                         if (order_to_size(this_order) < rq_size)
1541                                 break;
1542                 } while (1);
1543
1544                 if (!page)
1545                         goto fail;
1546
1547                 page->private = this_order;
1548                 list_add_tail(&page->lru, &tags->page_list);
1549
1550                 p = page_address(page);
1551                 /*
1552                  * Allow kmemleak to scan these pages as they contain pointers
1553                  * to additional allocations like via ops->init_request().
1554                  */
1555                 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_KERNEL);
1556                 entries_per_page = order_to_size(this_order) / rq_size;
1557                 to_do = min(entries_per_page, set->queue_depth - i);
1558                 left -= to_do * rq_size;
1559                 for (j = 0; j < to_do; j++) {
1560                         tags->rqs[i] = p;
1561                         if (set->ops->init_request) {
1562                                 if (set->ops->init_request(set->driver_data,
1563                                                 tags->rqs[i], hctx_idx, i,
1564                                                 set->numa_node)) {
1565                                         tags->rqs[i] = NULL;
1566                                         goto fail;
1567                                 }
1568                         }
1569
1570                         p += rq_size;
1571                         i++;
1572                 }
1573         }
1574         return tags;
1575
1576 fail:
1577         blk_mq_free_rq_map(set, tags, hctx_idx);
1578         return NULL;
1579 }
1580
1581 /*
1582  * 'cpu' is going away. splice any existing rq_list entries from this
1583  * software queue to the hw queue dispatch list, and ensure that it
1584  * gets run.
1585  */
1586 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
1587 {
1588         struct blk_mq_hw_ctx *hctx;
1589         struct blk_mq_ctx *ctx;
1590         LIST_HEAD(tmp);
1591
1592         hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
1593         ctx = __blk_mq_get_ctx(hctx->queue, cpu);
1594
1595         spin_lock(&ctx->lock);
1596         if (!list_empty(&ctx->rq_list)) {
1597                 list_splice_init(&ctx->rq_list, &tmp);
1598                 blk_mq_hctx_clear_pending(hctx, ctx);
1599         }
1600         spin_unlock(&ctx->lock);
1601
1602         if (list_empty(&tmp))
1603                 return 0;
1604
1605         spin_lock(&hctx->lock);
1606         list_splice_tail_init(&tmp, &hctx->dispatch);
1607         spin_unlock(&hctx->lock);
1608
1609         blk_mq_run_hw_queue(hctx, true);
1610         return 0;
1611 }
1612
1613 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
1614 {
1615         cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
1616                                             &hctx->cpuhp_dead);
1617 }
1618
1619 /* hctx->ctxs will be freed in queue's release handler */
1620 static void blk_mq_exit_hctx(struct request_queue *q,
1621                 struct blk_mq_tag_set *set,
1622                 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1623 {
1624         unsigned flush_start_tag = set->queue_depth;
1625
1626         blk_mq_tag_idle(hctx);
1627
1628         if (set->ops->exit_request)
1629                 set->ops->exit_request(set->driver_data,
1630                                        hctx->fq->flush_rq, hctx_idx,
1631                                        flush_start_tag + hctx_idx);
1632
1633         if (set->ops->exit_hctx)
1634                 set->ops->exit_hctx(hctx, hctx_idx);
1635
1636         blk_mq_remove_cpuhp(hctx);
1637         blk_free_flush_queue(hctx->fq);
1638         sbitmap_free(&hctx->ctx_map);
1639 }
1640
1641 static void blk_mq_exit_hw_queues(struct request_queue *q,
1642                 struct blk_mq_tag_set *set, int nr_queue)
1643 {
1644         struct blk_mq_hw_ctx *hctx;
1645         unsigned int i;
1646
1647         queue_for_each_hw_ctx(q, hctx, i) {
1648                 if (i == nr_queue)
1649                         break;
1650                 blk_mq_exit_hctx(q, set, hctx, i);
1651         }
1652 }
1653
1654 static void blk_mq_free_hw_queues(struct request_queue *q,
1655                 struct blk_mq_tag_set *set)
1656 {
1657         struct blk_mq_hw_ctx *hctx;
1658         unsigned int i;
1659
1660         queue_for_each_hw_ctx(q, hctx, i)
1661                 free_cpumask_var(hctx->cpumask);
1662 }
1663
1664 static int blk_mq_init_hctx(struct request_queue *q,
1665                 struct blk_mq_tag_set *set,
1666                 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
1667 {
1668         int node;
1669         unsigned flush_start_tag = set->queue_depth;
1670
1671         node = hctx->numa_node;
1672         if (node == NUMA_NO_NODE)
1673                 node = hctx->numa_node = set->numa_node;
1674
1675         INIT_WORK(&hctx->run_work, blk_mq_run_work_fn);
1676         INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
1677         spin_lock_init(&hctx->lock);
1678         INIT_LIST_HEAD(&hctx->dispatch);
1679         hctx->queue = q;
1680         hctx->queue_num = hctx_idx;
1681         hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
1682
1683         cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
1684
1685         hctx->tags = set->tags[hctx_idx];
1686
1687         /*
1688          * Allocate space for all possible cpus to avoid allocation at
1689          * runtime
1690          */
1691         hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1692                                         GFP_KERNEL, node);
1693         if (!hctx->ctxs)
1694                 goto unregister_cpu_notifier;
1695
1696         if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
1697                               node))
1698                 goto free_ctxs;
1699
1700         hctx->nr_ctx = 0;
1701
1702         if (set->ops->init_hctx &&
1703             set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
1704                 goto free_bitmap;
1705
1706         hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
1707         if (!hctx->fq)
1708                 goto exit_hctx;
1709
1710         if (set->ops->init_request &&
1711             set->ops->init_request(set->driver_data,
1712                                    hctx->fq->flush_rq, hctx_idx,
1713                                    flush_start_tag + hctx_idx, node))
1714                 goto free_fq;
1715
1716         return 0;
1717
1718  free_fq:
1719         kfree(hctx->fq);
1720  exit_hctx:
1721         if (set->ops->exit_hctx)
1722                 set->ops->exit_hctx(hctx, hctx_idx);
1723  free_bitmap:
1724         sbitmap_free(&hctx->ctx_map);
1725  free_ctxs:
1726         kfree(hctx->ctxs);
1727  unregister_cpu_notifier:
1728         blk_mq_remove_cpuhp(hctx);
1729         return -1;
1730 }
1731
1732 static void blk_mq_init_cpu_queues(struct request_queue *q,
1733                                    unsigned int nr_hw_queues)
1734 {
1735         unsigned int i;
1736
1737         for_each_possible_cpu(i) {
1738                 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1739                 struct blk_mq_hw_ctx *hctx;
1740
1741                 memset(__ctx, 0, sizeof(*__ctx));
1742                 __ctx->cpu = i;
1743                 spin_lock_init(&__ctx->lock);
1744                 INIT_LIST_HEAD(&__ctx->rq_list);
1745                 __ctx->queue = q;
1746
1747                 /* If the cpu isn't online, the cpu is mapped to first hctx */
1748                 if (!cpu_online(i))
1749                         continue;
1750
1751                 hctx = blk_mq_map_queue(q, i);
1752
1753                 /*
1754                  * Set local node, IFF we have more than one hw queue. If
1755                  * not, we remain on the home node of the device
1756                  */
1757                 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
1758                         hctx->numa_node = local_memory_node(cpu_to_node(i));
1759         }
1760 }
1761
1762 static void blk_mq_map_swqueue(struct request_queue *q,
1763                                const struct cpumask *online_mask)
1764 {
1765         unsigned int i;
1766         struct blk_mq_hw_ctx *hctx;
1767         struct blk_mq_ctx *ctx;
1768         struct blk_mq_tag_set *set = q->tag_set;
1769
1770         /*
1771          * Avoid others reading imcomplete hctx->cpumask through sysfs
1772          */
1773         mutex_lock(&q->sysfs_lock);
1774
1775         queue_for_each_hw_ctx(q, hctx, i) {
1776                 cpumask_clear(hctx->cpumask);
1777                 hctx->nr_ctx = 0;
1778         }
1779
1780         /*
1781          * Map software to hardware queues
1782          */
1783         for_each_possible_cpu(i) {
1784                 /* If the cpu isn't online, the cpu is mapped to first hctx */
1785                 if (!cpumask_test_cpu(i, online_mask))
1786                         continue;
1787
1788                 ctx = per_cpu_ptr(q->queue_ctx, i);
1789                 hctx = blk_mq_map_queue(q, i);
1790
1791                 cpumask_set_cpu(i, hctx->cpumask);
1792                 ctx->index_hw = hctx->nr_ctx;
1793                 hctx->ctxs[hctx->nr_ctx++] = ctx;
1794         }
1795
1796         mutex_unlock(&q->sysfs_lock);
1797
1798         queue_for_each_hw_ctx(q, hctx, i) {
1799                 /*
1800                  * If no software queues are mapped to this hardware queue,
1801                  * disable it and free the request entries.
1802                  */
1803                 if (!hctx->nr_ctx) {
1804                         if (set->tags[i]) {
1805                                 blk_mq_free_rq_map(set, set->tags[i], i);
1806                                 set->tags[i] = NULL;
1807                         }
1808                         hctx->tags = NULL;
1809                         continue;
1810                 }
1811
1812                 /* unmapped hw queue can be remapped after CPU topo changed */
1813                 if (!set->tags[i])
1814                         set->tags[i] = blk_mq_init_rq_map(set, i);
1815                 hctx->tags = set->tags[i];
1816                 WARN_ON(!hctx->tags);
1817
1818                 /*
1819                  * Set the map size to the number of mapped software queues.
1820                  * This is more accurate and more efficient than looping
1821                  * over all possibly mapped software queues.
1822                  */
1823                 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
1824
1825                 /*
1826                  * Initialize batch roundrobin counts
1827                  */
1828                 hctx->next_cpu = cpumask_first(hctx->cpumask);
1829                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1830         }
1831 }
1832
1833 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
1834 {
1835         struct blk_mq_hw_ctx *hctx;
1836         int i;
1837
1838         queue_for_each_hw_ctx(q, hctx, i) {
1839                 if (shared)
1840                         hctx->flags |= BLK_MQ_F_TAG_SHARED;
1841                 else
1842                         hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
1843         }
1844 }
1845
1846 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
1847 {
1848         struct request_queue *q;
1849
1850         list_for_each_entry(q, &set->tag_list, tag_set_list) {
1851                 blk_mq_freeze_queue(q);
1852                 queue_set_hctx_shared(q, shared);
1853                 blk_mq_unfreeze_queue(q);
1854         }
1855 }
1856
1857 static void blk_mq_del_queue_tag_set(struct request_queue *q)
1858 {
1859         struct blk_mq_tag_set *set = q->tag_set;
1860
1861         mutex_lock(&set->tag_list_lock);
1862         list_del_init(&q->tag_set_list);
1863         if (list_is_singular(&set->tag_list)) {
1864                 /* just transitioned to unshared */
1865                 set->flags &= ~BLK_MQ_F_TAG_SHARED;
1866                 /* update existing queue */
1867                 blk_mq_update_tag_set_depth(set, false);
1868         }
1869         mutex_unlock(&set->tag_list_lock);
1870 }
1871
1872 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
1873                                      struct request_queue *q)
1874 {
1875         q->tag_set = set;
1876
1877         mutex_lock(&set->tag_list_lock);
1878
1879         /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
1880         if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
1881                 set->flags |= BLK_MQ_F_TAG_SHARED;
1882                 /* update existing queue */
1883                 blk_mq_update_tag_set_depth(set, true);
1884         }
1885         if (set->flags & BLK_MQ_F_TAG_SHARED)
1886                 queue_set_hctx_shared(q, true);
1887         list_add_tail(&q->tag_set_list, &set->tag_list);
1888
1889         mutex_unlock(&set->tag_list_lock);
1890 }
1891
1892 /*
1893  * It is the actual release handler for mq, but we do it from
1894  * request queue's release handler for avoiding use-after-free
1895  * and headache because q->mq_kobj shouldn't have been introduced,
1896  * but we can't group ctx/kctx kobj without it.
1897  */
1898 void blk_mq_release(struct request_queue *q)
1899 {
1900         struct blk_mq_hw_ctx *hctx;
1901         unsigned int i;
1902
1903         /* hctx kobj stays in hctx */
1904         queue_for_each_hw_ctx(q, hctx, i) {
1905                 if (!hctx)
1906                         continue;
1907                 kfree(hctx->ctxs);
1908                 kfree(hctx);
1909         }
1910
1911         q->mq_map = NULL;
1912
1913         kfree(q->queue_hw_ctx);
1914
1915         /* ctx kobj stays in queue_ctx */
1916         free_percpu(q->queue_ctx);
1917 }
1918
1919 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
1920 {
1921         struct request_queue *uninit_q, *q;
1922
1923         uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
1924         if (!uninit_q)
1925                 return ERR_PTR(-ENOMEM);
1926
1927         q = blk_mq_init_allocated_queue(set, uninit_q);
1928         if (IS_ERR(q))
1929                 blk_cleanup_queue(uninit_q);
1930
1931         return q;
1932 }
1933 EXPORT_SYMBOL(blk_mq_init_queue);
1934
1935 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
1936                                                 struct request_queue *q)
1937 {
1938         int i, j;
1939         struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
1940
1941         blk_mq_sysfs_unregister(q);
1942         for (i = 0; i < set->nr_hw_queues; i++) {
1943                 int node;
1944
1945                 if (hctxs[i])
1946                         continue;
1947
1948                 node = blk_mq_hw_queue_to_node(q->mq_map, i);
1949                 hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
1950                                         GFP_KERNEL, node);
1951                 if (!hctxs[i])
1952                         break;
1953
1954                 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
1955                                                 node)) {
1956                         kfree(hctxs[i]);
1957                         hctxs[i] = NULL;
1958                         break;
1959                 }
1960
1961                 atomic_set(&hctxs[i]->nr_active, 0);
1962                 hctxs[i]->numa_node = node;
1963                 hctxs[i]->queue_num = i;
1964
1965                 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
1966                         free_cpumask_var(hctxs[i]->cpumask);
1967                         kfree(hctxs[i]);
1968                         hctxs[i] = NULL;
1969                         break;
1970                 }
1971                 blk_mq_hctx_kobj_init(hctxs[i]);
1972         }
1973         for (j = i; j < q->nr_hw_queues; j++) {
1974                 struct blk_mq_hw_ctx *hctx = hctxs[j];
1975
1976                 if (hctx) {
1977                         if (hctx->tags) {
1978                                 blk_mq_free_rq_map(set, hctx->tags, j);
1979                                 set->tags[j] = NULL;
1980                         }
1981                         blk_mq_exit_hctx(q, set, hctx, j);
1982                         free_cpumask_var(hctx->cpumask);
1983                         kobject_put(&hctx->kobj);
1984                         kfree(hctx->ctxs);
1985                         kfree(hctx);
1986                         hctxs[j] = NULL;
1987
1988                 }
1989         }
1990         q->nr_hw_queues = i;
1991         blk_mq_sysfs_register(q);
1992 }
1993
1994 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
1995                                                   struct request_queue *q)
1996 {
1997         /* mark the queue as mq asap */
1998         q->mq_ops = set->ops;
1999
2000         q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2001         if (!q->queue_ctx)
2002                 goto err_exit;
2003
2004         q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
2005                                                 GFP_KERNEL, set->numa_node);
2006         if (!q->queue_hw_ctx)
2007                 goto err_percpu;
2008
2009         q->mq_map = set->mq_map;
2010
2011         blk_mq_realloc_hw_ctxs(set, q);
2012         if (!q->nr_hw_queues)
2013                 goto err_hctxs;
2014
2015         INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2016         blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2017
2018         q->nr_queues = nr_cpu_ids;
2019
2020         q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2021
2022         if (!(set->flags & BLK_MQ_F_SG_MERGE))
2023                 q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
2024
2025         q->sg_reserved_size = INT_MAX;
2026
2027         INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2028         INIT_LIST_HEAD(&q->requeue_list);
2029         spin_lock_init(&q->requeue_lock);
2030
2031         if (q->nr_hw_queues > 1)
2032                 blk_queue_make_request(q, blk_mq_make_request);
2033         else
2034                 blk_queue_make_request(q, blk_sq_make_request);
2035
2036         /*
2037          * Do this after blk_queue_make_request() overrides it...
2038          */
2039         q->nr_requests = set->queue_depth;
2040
2041         if (set->ops->complete)
2042                 blk_queue_softirq_done(q, set->ops->complete);
2043
2044         blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2045
2046         get_online_cpus();
2047         mutex_lock(&all_q_mutex);
2048
2049         list_add_tail(&q->all_q_node, &all_q_list);
2050         blk_mq_add_queue_tag_set(set, q);
2051         blk_mq_map_swqueue(q, cpu_online_mask);
2052
2053         mutex_unlock(&all_q_mutex);
2054         put_online_cpus();
2055
2056         return q;
2057
2058 err_hctxs:
2059         kfree(q->queue_hw_ctx);
2060 err_percpu:
2061         free_percpu(q->queue_ctx);
2062 err_exit:
2063         q->mq_ops = NULL;
2064         return ERR_PTR(-ENOMEM);
2065 }
2066 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2067
2068 void blk_mq_free_queue(struct request_queue *q)
2069 {
2070         struct blk_mq_tag_set   *set = q->tag_set;
2071
2072         mutex_lock(&all_q_mutex);
2073         list_del_init(&q->all_q_node);
2074         mutex_unlock(&all_q_mutex);
2075
2076         blk_mq_del_queue_tag_set(q);
2077
2078         blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2079         blk_mq_free_hw_queues(q, set);
2080 }
2081
2082 /* Basically redo blk_mq_init_queue with queue frozen */
2083 static void blk_mq_queue_reinit(struct request_queue *q,
2084                                 const struct cpumask *online_mask)
2085 {
2086         WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2087
2088         blk_mq_sysfs_unregister(q);
2089
2090         /*
2091          * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2092          * we should change hctx numa_node according to new topology (this
2093          * involves free and re-allocate memory, worthy doing?)
2094          */
2095
2096         blk_mq_map_swqueue(q, online_mask);
2097
2098         blk_mq_sysfs_register(q);
2099 }
2100
2101 /*
2102  * New online cpumask which is going to be set in this hotplug event.
2103  * Declare this cpumasks as global as cpu-hotplug operation is invoked
2104  * one-by-one and dynamically allocating this could result in a failure.
2105  */
2106 static struct cpumask cpuhp_online_new;
2107
2108 static void blk_mq_queue_reinit_work(void)
2109 {
2110         struct request_queue *q;
2111
2112         mutex_lock(&all_q_mutex);
2113         /*
2114          * We need to freeze and reinit all existing queues.  Freezing
2115          * involves synchronous wait for an RCU grace period and doing it
2116          * one by one may take a long time.  Start freezing all queues in
2117          * one swoop and then wait for the completions so that freezing can
2118          * take place in parallel.
2119          */
2120         list_for_each_entry(q, &all_q_list, all_q_node)
2121                 blk_mq_freeze_queue_start(q);
2122         list_for_each_entry(q, &all_q_list, all_q_node) {
2123                 blk_mq_freeze_queue_wait(q);
2124
2125                 /*
2126                  * timeout handler can't touch hw queue during the
2127                  * reinitialization
2128                  */
2129                 del_timer_sync(&q->timeout);
2130         }
2131
2132         list_for_each_entry(q, &all_q_list, all_q_node)
2133                 blk_mq_queue_reinit(q, &cpuhp_online_new);
2134
2135         list_for_each_entry(q, &all_q_list, all_q_node)
2136                 blk_mq_unfreeze_queue(q);
2137
2138         mutex_unlock(&all_q_mutex);
2139 }
2140
2141 static int blk_mq_queue_reinit_dead(unsigned int cpu)
2142 {
2143         cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2144         blk_mq_queue_reinit_work();
2145         return 0;
2146 }
2147
2148 /*
2149  * Before hotadded cpu starts handling requests, new mappings must be
2150  * established.  Otherwise, these requests in hw queue might never be
2151  * dispatched.
2152  *
2153  * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2154  * for CPU0, and ctx1 for CPU1).
2155  *
2156  * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2157  * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2158  *
2159  * And then while running hw queue, flush_busy_ctxs() finds bit0 is set in
2160  * pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2161  * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list
2162  * is ignored.
2163  */
2164 static int blk_mq_queue_reinit_prepare(unsigned int cpu)
2165 {
2166         cpumask_copy(&cpuhp_online_new, cpu_online_mask);
2167         cpumask_set_cpu(cpu, &cpuhp_online_new);
2168         blk_mq_queue_reinit_work();
2169         return 0;
2170 }
2171
2172 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2173 {
2174         int i;
2175
2176         for (i = 0; i < set->nr_hw_queues; i++) {
2177                 set->tags[i] = blk_mq_init_rq_map(set, i);
2178                 if (!set->tags[i])
2179                         goto out_unwind;
2180         }
2181
2182         return 0;
2183
2184 out_unwind:
2185         while (--i >= 0)
2186                 blk_mq_free_rq_map(set, set->tags[i], i);
2187
2188         return -ENOMEM;
2189 }
2190
2191 /*
2192  * Allocate the request maps associated with this tag_set. Note that this
2193  * may reduce the depth asked for, if memory is tight. set->queue_depth
2194  * will be updated to reflect the allocated depth.
2195  */
2196 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2197 {
2198         unsigned int depth;
2199         int err;
2200
2201         depth = set->queue_depth;
2202         do {
2203                 err = __blk_mq_alloc_rq_maps(set);
2204                 if (!err)
2205                         break;
2206
2207                 set->queue_depth >>= 1;
2208                 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2209                         err = -ENOMEM;
2210                         break;
2211                 }
2212         } while (set->queue_depth);
2213
2214         if (!set->queue_depth || err) {
2215                 pr_err("blk-mq: failed to allocate request map\n");
2216                 return -ENOMEM;
2217         }
2218
2219         if (depth != set->queue_depth)
2220                 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2221                                                 depth, set->queue_depth);
2222
2223         return 0;
2224 }
2225
2226 /*
2227  * Alloc a tag set to be associated with one or more request queues.
2228  * May fail with EINVAL for various error conditions. May adjust the
2229  * requested depth down, if if it too large. In that case, the set
2230  * value will be stored in set->queue_depth.
2231  */
2232 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2233 {
2234         int ret;
2235
2236         BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2237
2238         if (!set->nr_hw_queues)
2239                 return -EINVAL;
2240         if (!set->queue_depth)
2241                 return -EINVAL;
2242         if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2243                 return -EINVAL;
2244
2245         if (!set->ops->queue_rq)
2246                 return -EINVAL;
2247
2248         if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2249                 pr_info("blk-mq: reduced tag depth to %u\n",
2250                         BLK_MQ_MAX_DEPTH);
2251                 set->queue_depth = BLK_MQ_MAX_DEPTH;
2252         }
2253
2254         /*
2255          * If a crashdump is active, then we are potentially in a very
2256          * memory constrained environment. Limit us to 1 queue and
2257          * 64 tags to prevent using too much memory.
2258          */
2259         if (is_kdump_kernel()) {
2260                 set->nr_hw_queues = 1;
2261                 set->queue_depth = min(64U, set->queue_depth);
2262         }
2263         /*
2264          * There is no use for more h/w queues than cpus.
2265          */
2266         if (set->nr_hw_queues > nr_cpu_ids)
2267                 set->nr_hw_queues = nr_cpu_ids;
2268
2269         set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2270                                  GFP_KERNEL, set->numa_node);
2271         if (!set->tags)
2272                 return -ENOMEM;
2273
2274         ret = -ENOMEM;
2275         set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
2276                         GFP_KERNEL, set->numa_node);
2277         if (!set->mq_map)
2278                 goto out_free_tags;
2279
2280         if (set->ops->map_queues)
2281                 ret = set->ops->map_queues(set);
2282         else
2283                 ret = blk_mq_map_queues(set);
2284         if (ret)
2285                 goto out_free_mq_map;
2286
2287         ret = blk_mq_alloc_rq_maps(set);
2288         if (ret)
2289                 goto out_free_mq_map;
2290
2291         mutex_init(&set->tag_list_lock);
2292         INIT_LIST_HEAD(&set->tag_list);
2293
2294         return 0;
2295
2296 out_free_mq_map:
2297         kfree(set->mq_map);
2298         set->mq_map = NULL;
2299 out_free_tags:
2300         kfree(set->tags);
2301         set->tags = NULL;
2302         return ret;
2303 }
2304 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2305
2306 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2307 {
2308         int i;
2309
2310         for (i = 0; i < nr_cpu_ids; i++) {
2311                 if (set->tags[i])
2312                         blk_mq_free_rq_map(set, set->tags[i], i);
2313         }
2314
2315         kfree(set->mq_map);
2316         set->mq_map = NULL;
2317
2318         kfree(set->tags);
2319         set->tags = NULL;
2320 }
2321 EXPORT_SYMBOL(blk_mq_free_tag_set);
2322
2323 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2324 {
2325         struct blk_mq_tag_set *set = q->tag_set;
2326         struct blk_mq_hw_ctx *hctx;
2327         int i, ret;
2328
2329         if (!set || nr > set->queue_depth)
2330                 return -EINVAL;
2331
2332         ret = 0;
2333         queue_for_each_hw_ctx(q, hctx, i) {
2334                 if (!hctx->tags)
2335                         continue;
2336                 ret = blk_mq_tag_update_depth(hctx->tags, nr);
2337                 if (ret)
2338                         break;
2339         }
2340
2341         if (!ret)
2342                 q->nr_requests = nr;
2343
2344         return ret;
2345 }
2346
2347 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2348 {
2349         struct request_queue *q;
2350
2351         if (nr_hw_queues > nr_cpu_ids)
2352                 nr_hw_queues = nr_cpu_ids;
2353         if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2354                 return;
2355
2356         list_for_each_entry(q, &set->tag_list, tag_set_list)
2357                 blk_mq_freeze_queue(q);
2358
2359         set->nr_hw_queues = nr_hw_queues;
2360         list_for_each_entry(q, &set->tag_list, tag_set_list) {
2361                 blk_mq_realloc_hw_ctxs(set, q);
2362
2363                 if (q->nr_hw_queues > 1)
2364                         blk_queue_make_request(q, blk_mq_make_request);
2365                 else
2366                         blk_queue_make_request(q, blk_sq_make_request);
2367
2368                 blk_mq_queue_reinit(q, cpu_online_mask);
2369         }
2370
2371         list_for_each_entry(q, &set->tag_list, tag_set_list)
2372                 blk_mq_unfreeze_queue(q);
2373 }
2374 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2375
2376 void blk_mq_disable_hotplug(void)
2377 {
2378         mutex_lock(&all_q_mutex);
2379 }
2380
2381 void blk_mq_enable_hotplug(void)
2382 {
2383         mutex_unlock(&all_q_mutex);
2384 }
2385
2386 static int __init blk_mq_init(void)
2387 {
2388         cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
2389                                 blk_mq_hctx_notify_dead);
2390
2391         cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE, "block/mq:prepare",
2392                                   blk_mq_queue_reinit_prepare,
2393                                   blk_mq_queue_reinit_dead);
2394         return 0;
2395 }
2396 subsys_initcall(blk_mq_init);