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