block/blk-mq.c

   1 #include <linux/kernel.h>
   2 #include <linux/module.h>
   3 #include <linux/backing-dev.h>
   4 #include <linux/bio.h>
   5 #include <linux/blkdev.h>
   6 #include <linux/mm.h>
   7 #include <linux/init.h>
   8 #include <linux/slab.h>
   9 #include <linux/workqueue.h>
  10 #include <linux/smp.h>
  11 #include <linux/llist.h>
  12 #include <linux/list_sort.h>
  13 #include <linux/cpu.h>
  14 #include <linux/cache.h>
  15 #include <linux/sched/sysctl.h>
  16 #include <linux/delay.h>
  17
  18 #include <trace/events/block.h>
  19
  20 #include <linux/blk-mq.h>
  21 #include "blk.h"
  22 #include "blk-mq.h"
  23 #include "blk-mq-tag.h"
  24
  25 static DEFINE_MUTEX(all_q_mutex);
  26 static LIST_HEAD(all_q_list);
  27
  28 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx);
  29
  30 static struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
  31                                            unsigned int cpu)
  32 {
  33         return per_cpu_ptr(q->queue_ctx, cpu);
  34 }
  35
  36 /*
  37  * This assumes per-cpu software queueing queues. They could be per-node
  38  * as well, for instance. For now this is hardcoded as-is. Note that we don't
  39  * care about preemption, since we know the ctx's are persistent. This does
  40  * mean that we can't rely on ctx always matching the currently running CPU.
  41  */
  42 static struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q)
  43 {
  44         return __blk_mq_get_ctx(q, get_cpu());
  45 }
  46
  47 static void blk_mq_put_ctx(struct blk_mq_ctx *ctx)
  48 {
  49         put_cpu();
  50 }
  51
  52 /*
  53  * Check if any of the ctx's have pending work in this hardware queue
  54  */
  55 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
  56 {
  57         unsigned int i;
  58
  59         for (i = 0; i < hctx->nr_ctx_map; i++)
  60                 if (hctx->ctx_map[i])
  61                         return true;
  62
  63         return false;
  64 }
  65
  66 /*
  67  * Mark this ctx as having pending work in this hardware queue
  68  */
  69 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
  70                                      struct blk_mq_ctx *ctx)
  71 {
  72         if (!test_bit(ctx->index_hw, hctx->ctx_map))
  73                 set_bit(ctx->index_hw, hctx->ctx_map);
  74 }
  75
  76 static struct request *__blk_mq_alloc_request(struct blk_mq_hw_ctx *hctx,
  77                                               struct blk_mq_ctx *ctx,
  78                                               gfp_t gfp, bool reserved)
  79 {
  80         struct request *rq;
  81         unsigned int tag;
  82
  83         tag = blk_mq_get_tag(hctx, &ctx->last_tag, gfp, reserved);
  84         if (tag != BLK_MQ_TAG_FAIL) {
  85                 rq = hctx->tags->rqs[tag];
  86
  87                 rq->cmd_flags = 0;
  88                 if (blk_mq_tag_busy(hctx)) {
  89                         rq->cmd_flags = REQ_MQ_INFLIGHT;
  90                         atomic_inc(&hctx->nr_active);
  91                 }
  92
  93                 rq->tag = tag;
  94                 return rq;
  95         }
  96
  97         return NULL;
  98 }
  99
 100 static int blk_mq_queue_enter(struct request_queue *q)
 101 {
 102         int ret;
 103
 104         __percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
 105         smp_wmb();
 106         /* we have problems to freeze the queue if it's initializing */
 107         if (!blk_queue_bypass(q) || !blk_queue_init_done(q))
 108                 return 0;
 109
 110         __percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
 111
 112         spin_lock_irq(q->queue_lock);
 113         ret = wait_event_interruptible_lock_irq(q->mq_freeze_wq,
 114                 !blk_queue_bypass(q) || blk_queue_dying(q),
 115                 *q->queue_lock);
 116         /* inc usage with lock hold to avoid freeze_queue runs here */
 117         if (!ret && !blk_queue_dying(q))
 118                 __percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
 119         else if (blk_queue_dying(q))
 120                 ret = -ENODEV;
 121         spin_unlock_irq(q->queue_lock);
 122
 123         return ret;
 124 }
 125
 126 static void blk_mq_queue_exit(struct request_queue *q)
 127 {
 128         __percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
 129 }
 130
 131 static void __blk_mq_drain_queue(struct request_queue *q)
 132 {
 133         while (true) {
 134                 s64 count;
 135
 136                 spin_lock_irq(q->queue_lock);
 137                 count = percpu_counter_sum(&q->mq_usage_counter);
 138                 spin_unlock_irq(q->queue_lock);
 139
 140                 if (count == 0)
 141                         break;
 142                 blk_mq_run_queues(q, false);
 143                 msleep(10);
 144         }
 145 }
 146
 147 /*
 148  * Guarantee no request is in use, so we can change any data structure of
 149  * the queue afterward.
 150  */
 151 static void blk_mq_freeze_queue(struct request_queue *q)
 152 {
 153         bool drain;
 154
 155         spin_lock_irq(q->queue_lock);
 156         drain = !q->bypass_depth++;
 157         queue_flag_set(QUEUE_FLAG_BYPASS, q);
 158         spin_unlock_irq(q->queue_lock);
 159
 160         if (drain)
 161                 __blk_mq_drain_queue(q);
 162 }
 163
 164 void blk_mq_drain_queue(struct request_queue *q)
 165 {
 166         __blk_mq_drain_queue(q);
 167 }
 168
 169 static void blk_mq_unfreeze_queue(struct request_queue *q)
 170 {
 171         bool wake = false;
 172
 173         spin_lock_irq(q->queue_lock);
 174         if (!--q->bypass_depth) {
 175                 queue_flag_clear(QUEUE_FLAG_BYPASS, q);
 176                 wake = true;
 177         }
 178         WARN_ON_ONCE(q->bypass_depth < 0);
 179         spin_unlock_irq(q->queue_lock);
 180         if (wake)
 181                 wake_up_all(&q->mq_freeze_wq);
 182 }
 183
 184 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
 185 {
 186         return blk_mq_has_free_tags(hctx->tags);
 187 }
 188 EXPORT_SYMBOL(blk_mq_can_queue);
 189
 190 static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
 191                                struct request *rq, unsigned int rw_flags)
 192 {
 193         if (blk_queue_io_stat(q))
 194                 rw_flags |= REQ_IO_STAT;
 195
 196         INIT_LIST_HEAD(&rq->queuelist);
 197         /* csd/requeue_work/fifo_time is initialized before use */
 198         rq->q = q;
 199         rq->mq_ctx = ctx;
 200         rq->cmd_flags |= rw_flags;
 201         rq->cmd_type = 0;
 202         /* do not touch atomic flags, it needs atomic ops against the timer */
 203         rq->cpu = -1;
 204         rq->__data_len = 0;
 205         rq->__sector = (sector_t) -1;
 206         rq->bio = NULL;
 207         rq->biotail = NULL;
 208         INIT_HLIST_NODE(&rq->hash);
 209         RB_CLEAR_NODE(&rq->rb_node);
 210         memset(&rq->flush, 0, max(sizeof(rq->flush), sizeof(rq->elv)));
 211         rq->rq_disk = NULL;
 212         rq->part = NULL;
 213         rq->start_time = jiffies;
 214 #ifdef CONFIG_BLK_CGROUP
 215         rq->rl = NULL;
 216         set_start_time_ns(rq);
 217         rq->io_start_time_ns = 0;
 218 #endif
 219         rq->nr_phys_segments = 0;
 220 #if defined(CONFIG_BLK_DEV_INTEGRITY)
 221         rq->nr_integrity_segments = 0;
 222 #endif
 223         rq->ioprio = 0;
 224         rq->special = NULL;
 225         /* tag was already set */
 226         rq->errors = 0;
 227         memset(rq->__cmd, 0, sizeof(rq->__cmd));
 228         rq->cmd = rq->__cmd;
 229         rq->cmd_len = BLK_MAX_CDB;
 230
 231         rq->extra_len = 0;
 232         rq->sense_len = 0;
 233         rq->resid_len = 0;
 234         rq->sense = NULL;
 235
 236         rq->deadline = 0;
 237         INIT_LIST_HEAD(&rq->timeout_list);
 238         rq->timeout = 0;
 239         rq->retries = 0;
 240         rq->end_io = NULL;
 241         rq->end_io_data = NULL;
 242         rq->next_rq = NULL;
 243
 244         ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
 245 }
 246
 247 static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
 248                                                    int rw, gfp_t gfp,
 249                                                    bool reserved)
 250 {
 251         struct request *rq;
 252
 253         do {
 254                 struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
 255                 struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);
 256
 257                 rq = __blk_mq_alloc_request(hctx, ctx, gfp & ~__GFP_WAIT,
 258                                                 reserved);
 259                 if (rq) {
 260                         blk_mq_rq_ctx_init(q, ctx, rq, rw);
 261                         break;
 262                 }
 263
 264                 if (gfp & __GFP_WAIT) {
 265                         __blk_mq_run_hw_queue(hctx);
 266                         blk_mq_put_ctx(ctx);
 267                 } else {
 268                         blk_mq_put_ctx(ctx);
 269                         break;
 270                 }
 271
 272                 blk_mq_wait_for_tags(hctx, reserved);
 273         } while (1);
 274
 275         return rq;
 276 }
 277
 278 struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp)
 279 {
 280         struct request *rq;
 281
 282         if (blk_mq_queue_enter(q))
 283                 return NULL;
 284
 285         rq = blk_mq_alloc_request_pinned(q, rw, gfp, false);
 286         if (rq)
 287                 blk_mq_put_ctx(rq->mq_ctx);
 288         return rq;
 289 }
 290 EXPORT_SYMBOL(blk_mq_alloc_request);
 291
 292 struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
 293                                               gfp_t gfp)
 294 {
 295         struct request *rq;
 296
 297         if (blk_mq_queue_enter(q))
 298                 return NULL;
 299
 300         rq = blk_mq_alloc_request_pinned(q, rw, gfp, true);
 301         if (rq)
 302                 blk_mq_put_ctx(rq->mq_ctx);
 303         return rq;
 304 }
 305 EXPORT_SYMBOL(blk_mq_alloc_reserved_request);
 306
 307 static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
 308                                   struct blk_mq_ctx *ctx, struct request *rq)
 309 {
 310         const int tag = rq->tag;
 311         struct request_queue *q = rq->q;
 312
 313         if (rq->cmd_flags & REQ_MQ_INFLIGHT)
 314                 atomic_dec(&hctx->nr_active);
 315
 316         clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 317         blk_mq_put_tag(hctx, tag, &ctx->last_tag);
 318         blk_mq_queue_exit(q);
 319 }
 320
 321 void blk_mq_free_request(struct request *rq)
 322 {
 323         struct blk_mq_ctx *ctx = rq->mq_ctx;
 324         struct blk_mq_hw_ctx *hctx;
 325         struct request_queue *q = rq->q;
 326
 327         ctx->rq_completed[rq_is_sync(rq)]++;
 328
 329         hctx = q->mq_ops->map_queue(q, ctx->cpu);
 330         __blk_mq_free_request(hctx, ctx, rq);
 331 }
 332
 333 /*
 334  * Clone all relevant state from a request that has been put on hold in
 335  * the flush state machine into the preallocated flush request that hangs
 336  * off the request queue.
 337  *
 338  * For a driver the flush request should be invisible, that's why we are
 339  * impersonating the original request here.
 340  */
 341 void blk_mq_clone_flush_request(struct request *flush_rq,
 342                 struct request *orig_rq)
 343 {
 344         struct blk_mq_hw_ctx *hctx =
 345                 orig_rq->q->mq_ops->map_queue(orig_rq->q, orig_rq->mq_ctx->cpu);
 346
 347         flush_rq->mq_ctx = orig_rq->mq_ctx;
 348         flush_rq->tag = orig_rq->tag;
 349         memcpy(blk_mq_rq_to_pdu(flush_rq), blk_mq_rq_to_pdu(orig_rq),
 350                 hctx->cmd_size);
 351 }
 352
 353 inline void __blk_mq_end_io(struct request *rq, int error)
 354 {
 355         blk_account_io_done(rq);
 356
 357         if (rq->end_io) {
 358                 rq->end_io(rq, error);
 359         } else {
 360                 if (unlikely(blk_bidi_rq(rq)))
 361                         blk_mq_free_request(rq->next_rq);
 362                 blk_mq_free_request(rq);
 363         }
 364 }
 365 EXPORT_SYMBOL(__blk_mq_end_io);
 366
 367 void blk_mq_end_io(struct request *rq, int error)
 368 {
 369         if (blk_update_request(rq, error, blk_rq_bytes(rq)))
 370                 BUG();
 371         __blk_mq_end_io(rq, error);
 372 }
 373 EXPORT_SYMBOL(blk_mq_end_io);
 374
 375 static void __blk_mq_complete_request_remote(void *data)
 376 {
 377         struct request *rq = data;
 378
 379         rq->q->softirq_done_fn(rq);
 380 }
 381
 382 void __blk_mq_complete_request(struct request *rq)
 383 {
 384         struct blk_mq_ctx *ctx = rq->mq_ctx;
 385         bool shared = false;
 386         int cpu;
 387
 388         if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
 389                 rq->q->softirq_done_fn(rq);
 390                 return;
 391         }
 392
 393         cpu = get_cpu();
 394         if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
 395                 shared = cpus_share_cache(cpu, ctx->cpu);
 396
 397         if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
 398                 rq->csd.func = __blk_mq_complete_request_remote;
 399                 rq->csd.info = rq;
 400                 rq->csd.flags = 0;
 401                 smp_call_function_single_async(ctx->cpu, &rq->csd);
 402         } else {
 403                 rq->q->softirq_done_fn(rq);
 404         }
 405         put_cpu();
 406 }
 407
 408 /**
 409  * blk_mq_complete_request - end I/O on a request
 410  * @rq:         the request being processed
 411  *
 412  * Description:
 413  *      Ends all I/O on a request. It does not handle partial completions.
 414  *      The actual completion happens out-of-order, through a IPI handler.
 415  **/
 416 void blk_mq_complete_request(struct request *rq)
 417 {
 418         if (unlikely(blk_should_fake_timeout(rq->q)))
 419                 return;
 420         if (!blk_mark_rq_complete(rq))
 421                 __blk_mq_complete_request(rq);
 422 }
 423 EXPORT_SYMBOL(blk_mq_complete_request);
 424
 425 static void blk_mq_start_request(struct request *rq, bool last)
 426 {
 427         struct request_queue *q = rq->q;
 428
 429         trace_block_rq_issue(q, rq);
 430
 431         rq->resid_len = blk_rq_bytes(rq);
 432         if (unlikely(blk_bidi_rq(rq)))
 433                 rq->next_rq->resid_len = blk_rq_bytes(rq->next_rq);
 434
 435         /*
 436          * Just mark start time and set the started bit. Due to memory
 437          * ordering, we know we'll see the correct deadline as long as
 438          * REQ_ATOMIC_STARTED is seen.
 439          */
 440         rq->deadline = jiffies + q->rq_timeout;
 441
 442         /*
 443          * Mark us as started and clear complete. Complete might have been
 444          * set if requeue raced with timeout, which then marked it as
 445          * complete. So be sure to clear complete again when we start
 446          * the request, otherwise we'll ignore the completion event.
 447          */
 448         set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 449         clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
 450
 451         if (q->dma_drain_size && blk_rq_bytes(rq)) {
 452                 /*
 453                  * Make sure space for the drain appears.  We know we can do
 454                  * this because max_hw_segments has been adjusted to be one
 455                  * fewer than the device can handle.
 456                  */
 457                 rq->nr_phys_segments++;
 458         }
 459
 460         /*
 461          * Flag the last request in the series so that drivers know when IO
 462          * should be kicked off, if they don't do it on a per-request basis.
 463          *
 464          * Note: the flag isn't the only condition drivers should do kick off.
 465          * If drive is busy, the last request might not have the bit set.
 466          */
 467         if (last)
 468                 rq->cmd_flags |= REQ_END;
 469 }
 470
 471 static void __blk_mq_requeue_request(struct request *rq)
 472 {
 473         struct request_queue *q = rq->q;
 474
 475         trace_block_rq_requeue(q, rq);
 476         clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
 477
 478         rq->cmd_flags &= ~REQ_END;
 479
 480         if (q->dma_drain_size && blk_rq_bytes(rq))
 481                 rq->nr_phys_segments--;
 482 }
 483
 484 void blk_mq_requeue_request(struct request *rq)
 485 {
 486         __blk_mq_requeue_request(rq);
 487         blk_clear_rq_complete(rq);
 488
 489         BUG_ON(blk_queued_rq(rq));
 490         blk_mq_insert_request(rq, true, true, false);
 491 }
 492 EXPORT_SYMBOL(blk_mq_requeue_request);
 493
 494 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
 495 {
 496         return tags->rqs[tag];
 497 }
 498 EXPORT_SYMBOL(blk_mq_tag_to_rq);
 499
 500 struct blk_mq_timeout_data {
 501         struct blk_mq_hw_ctx *hctx;
 502         unsigned long *next;
 503         unsigned int *next_set;
 504 };
 505
 506 static void blk_mq_timeout_check(void *__data, unsigned long *free_tags)
 507 {
 508         struct blk_mq_timeout_data *data = __data;
 509         struct blk_mq_hw_ctx *hctx = data->hctx;
 510         unsigned int tag;
 511
 512          /* It may not be in flight yet (this is where
 513          * the REQ_ATOMIC_STARTED flag comes in). The requests are
 514          * statically allocated, so we know it's always safe to access the
 515          * memory associated with a bit offset into ->rqs[].
 516          */
 517         tag = 0;
 518         do {
 519                 struct request *rq;
 520
 521                 tag = find_next_zero_bit(free_tags, hctx->tags->nr_tags, tag);
 522                 if (tag >= hctx->tags->nr_tags)
 523                         break;
 524
 525                 rq = blk_mq_tag_to_rq(hctx->tags, tag++);
 526                 if (rq->q != hctx->queue)
 527                         continue;
 528                 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
 529                         continue;
 530
 531                 blk_rq_check_expired(rq, data->next, data->next_set);
 532         } while (1);
 533 }
 534
 535 static void blk_mq_hw_ctx_check_timeout(struct blk_mq_hw_ctx *hctx,
 536                                         unsigned long *next,
 537                                         unsigned int *next_set)
 538 {
 539         struct blk_mq_timeout_data data = {
 540                 .hctx           = hctx,
 541                 .next           = next,
 542                 .next_set       = next_set,
 543         };
 544
 545         /*
 546          * Ask the tagging code to iterate busy requests, so we can
 547          * check them for timeout.
 548          */
 549         blk_mq_tag_busy_iter(hctx->tags, blk_mq_timeout_check, &data);
 550 }
 551
 552 static enum blk_eh_timer_return blk_mq_rq_timed_out(struct request *rq)
 553 {
 554         struct request_queue *q = rq->q;
 555
 556         /*
 557          * We know that complete is set at this point. If STARTED isn't set
 558          * anymore, then the request isn't active and the "timeout" should
 559          * just be ignored. This can happen due to the bitflag ordering.
 560          * Timeout first checks if STARTED is set, and if it is, assumes
 561          * the request is active. But if we race with completion, then
 562          * we both flags will get cleared. So check here again, and ignore
 563          * a timeout event with a request that isn't active.
 564          */
 565         if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
 566                 return BLK_EH_NOT_HANDLED;
 567
 568         if (!q->mq_ops->timeout)
 569                 return BLK_EH_RESET_TIMER;
 570
 571         return q->mq_ops->timeout(rq);
 572 }
 573
 574 static void blk_mq_rq_timer(unsigned long data)
 575 {
 576         struct request_queue *q = (struct request_queue *) data;
 577         struct blk_mq_hw_ctx *hctx;
 578         unsigned long next = 0;
 579         int i, next_set = 0;
 580
 581         queue_for_each_hw_ctx(q, hctx, i)
 582                 blk_mq_hw_ctx_check_timeout(hctx, &next, &next_set);
 583
 584         if (next_set) {
 585                 next = blk_rq_timeout(round_jiffies_up(next));
 586                 mod_timer(&q->timeout, next);
 587         } else {
 588                 queue_for_each_hw_ctx(q, hctx, i)
 589                         blk_mq_tag_idle(hctx);
 590         }
 591 }
 592
 593 /*
 594  * Reverse check our software queue for entries that we could potentially
 595  * merge with. Currently includes a hand-wavy stop count of 8, to not spend
 596  * too much time checking for merges.
 597  */
 598 static bool blk_mq_attempt_merge(struct request_queue *q,
 599                                  struct blk_mq_ctx *ctx, struct bio *bio)
 600 {
 601         struct request *rq;
 602         int checked = 8;
 603
 604         list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
 605                 int el_ret;
 606
 607                 if (!checked--)
 608                         break;
 609
 610                 if (!blk_rq_merge_ok(rq, bio))
 611                         continue;
 612
 613                 el_ret = blk_try_merge(rq, bio);
 614                 if (el_ret == ELEVATOR_BACK_MERGE) {
 615                         if (bio_attempt_back_merge(q, rq, bio)) {
 616                                 ctx->rq_merged++;
 617                                 return true;
 618                         }
 619                         break;
 620                 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
 621                         if (bio_attempt_front_merge(q, rq, bio)) {
 622                                 ctx->rq_merged++;
 623                                 return true;
 624                         }
 625                         break;
 626                 }
 627         }
 628
 629         return false;
 630 }
 631
 632 /*
 633  * Run this hardware queue, pulling any software queues mapped to it in.
 634  * Note that this function currently has various problems around ordering
 635  * of IO. In particular, we'd like FIFO behaviour on handling existing
 636  * items on the hctx->dispatch list. Ignore that for now.
 637  */
 638 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
 639 {
 640         struct request_queue *q = hctx->queue;
 641         struct blk_mq_ctx *ctx;
 642         struct request *rq;
 643         LIST_HEAD(rq_list);
 644         int bit, queued;
 645
 646         WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask));
 647
 648         if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
 649                 return;
 650
 651         hctx->run++;
 652
 653         /*
 654          * Touch any software queue that has pending entries.
 655          */
 656         for_each_set_bit(bit, hctx->ctx_map, hctx->nr_ctx) {
 657                 clear_bit(bit, hctx->ctx_map);
 658                 ctx = hctx->ctxs[bit];
 659
 660                 spin_lock(&ctx->lock);
 661                 list_splice_tail_init(&ctx->rq_list, &rq_list);
 662                 spin_unlock(&ctx->lock);
 663         }
 664
 665         /*
 666          * If we have previous entries on our dispatch list, grab them
 667          * and stuff them at the front for more fair dispatch.
 668          */
 669         if (!list_empty_careful(&hctx->dispatch)) {
 670                 spin_lock(&hctx->lock);
 671                 if (!list_empty(&hctx->dispatch))
 672                         list_splice_init(&hctx->dispatch, &rq_list);
 673                 spin_unlock(&hctx->lock);
 674         }
 675
 676         /*
 677          * Delete and return all entries from our dispatch list
 678          */
 679         queued = 0;
 680
 681         /*
 682          * Now process all the entries, sending them to the driver.
 683          */
 684         while (!list_empty(&rq_list)) {
 685                 int ret;
 686
 687                 rq = list_first_entry(&rq_list, struct request, queuelist);
 688                 list_del_init(&rq->queuelist);
 689
 690                 blk_mq_start_request(rq, list_empty(&rq_list));
 691
 692                 ret = q->mq_ops->queue_rq(hctx, rq);
 693                 switch (ret) {
 694                 case BLK_MQ_RQ_QUEUE_OK:
 695                         queued++;
 696                         continue;
 697                 case BLK_MQ_RQ_QUEUE_BUSY:
 698                         list_add(&rq->queuelist, &rq_list);
 699                         __blk_mq_requeue_request(rq);
 700                         break;
 701                 default:
 702                         pr_err("blk-mq: bad return on queue: %d\n", ret);
 703                 case BLK_MQ_RQ_QUEUE_ERROR:
 704                         rq->errors = -EIO;
 705                         blk_mq_end_io(rq, rq->errors);
 706                         break;
 707                 }
 708
 709                 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
 710                         break;
 711         }
 712
 713         if (!queued)
 714                 hctx->dispatched[0]++;
 715         else if (queued < (1 << (BLK_MQ_MAX_DISPATCH_ORDER - 1)))
 716                 hctx->dispatched[ilog2(queued) + 1]++;
 717
 718         /*
 719          * Any items that need requeuing? Stuff them into hctx->dispatch,
 720          * that is where we will continue on next queue run.
 721          */
 722         if (!list_empty(&rq_list)) {
 723                 spin_lock(&hctx->lock);
 724                 list_splice(&rq_list, &hctx->dispatch);
 725                 spin_unlock(&hctx->lock);
 726         }
 727 }
 728
 729 /*
 730  * It'd be great if the workqueue API had a way to pass
 731  * in a mask and had some smarts for more clever placement.
 732  * For now we just round-robin here, switching for every
 733  * BLK_MQ_CPU_WORK_BATCH queued items.
 734  */
 735 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
 736 {
 737         int cpu = hctx->next_cpu;
 738
 739         if (--hctx->next_cpu_batch <= 0) {
 740                 int next_cpu;
 741
 742                 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
 743                 if (next_cpu >= nr_cpu_ids)
 744                         next_cpu = cpumask_first(hctx->cpumask);
 745
 746                 hctx->next_cpu = next_cpu;
 747                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
 748         }
 749
 750         return cpu;
 751 }
 752
 753 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
 754 {
 755         if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
 756                 return;
 757
 758         if (!async && cpumask_test_cpu(smp_processor_id(), hctx->cpumask))
 759                 __blk_mq_run_hw_queue(hctx);
 760         else if (hctx->queue->nr_hw_queues == 1)
 761                 kblockd_schedule_delayed_work(&hctx->run_work, 0);
 762         else {
 763                 unsigned int cpu;
 764
 765                 cpu = blk_mq_hctx_next_cpu(hctx);
 766                 kblockd_schedule_delayed_work_on(cpu, &hctx->run_work, 0);
 767         }
 768 }
 769
 770 void blk_mq_run_queues(struct request_queue *q, bool async)
 771 {
 772         struct blk_mq_hw_ctx *hctx;
 773         int i;
 774
 775         queue_for_each_hw_ctx(q, hctx, i) {
 776                 if ((!blk_mq_hctx_has_pending(hctx) &&
 777                     list_empty_careful(&hctx->dispatch)) ||
 778                     test_bit(BLK_MQ_S_STOPPED, &hctx->state))
 779                         continue;
 780
 781                 preempt_disable();
 782                 blk_mq_run_hw_queue(hctx, async);
 783                 preempt_enable();
 784         }
 785 }
 786 EXPORT_SYMBOL(blk_mq_run_queues);
 787
 788 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
 789 {
 790         cancel_delayed_work(&hctx->run_work);
 791         cancel_delayed_work(&hctx->delay_work);
 792         set_bit(BLK_MQ_S_STOPPED, &hctx->state);
 793 }
 794 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
 795
 796 void blk_mq_stop_hw_queues(struct request_queue *q)
 797 {
 798         struct blk_mq_hw_ctx *hctx;
 799         int i;
 800
 801         queue_for_each_hw_ctx(q, hctx, i)
 802                 blk_mq_stop_hw_queue(hctx);
 803 }
 804 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
 805
 806 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
 807 {
 808         clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
 809
 810         preempt_disable();
 811         __blk_mq_run_hw_queue(hctx);
 812         preempt_enable();
 813 }
 814 EXPORT_SYMBOL(blk_mq_start_hw_queue);
 815
 816 void blk_mq_start_hw_queues(struct request_queue *q)
 817 {
 818         struct blk_mq_hw_ctx *hctx;
 819         int i;
 820
 821         queue_for_each_hw_ctx(q, hctx, i)
 822                 blk_mq_start_hw_queue(hctx);
 823 }
 824 EXPORT_SYMBOL(blk_mq_start_hw_queues);
 825
 826
 827 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
 828 {
 829         struct blk_mq_hw_ctx *hctx;
 830         int i;
 831
 832         queue_for_each_hw_ctx(q, hctx, i) {
 833                 if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
 834                         continue;
 835
 836                 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
 837                 preempt_disable();
 838                 blk_mq_run_hw_queue(hctx, async);
 839                 preempt_enable();
 840         }
 841 }
 842 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
 843
 844 static void blk_mq_run_work_fn(struct work_struct *work)
 845 {
 846         struct blk_mq_hw_ctx *hctx;
 847
 848         hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
 849
 850         __blk_mq_run_hw_queue(hctx);
 851 }
 852
 853 static void blk_mq_delay_work_fn(struct work_struct *work)
 854 {
 855         struct blk_mq_hw_ctx *hctx;
 856
 857         hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
 858
 859         if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
 860                 __blk_mq_run_hw_queue(hctx);
 861 }
 862
 863 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
 864 {
 865         unsigned long tmo = msecs_to_jiffies(msecs);
 866
 867         if (hctx->queue->nr_hw_queues == 1)
 868                 kblockd_schedule_delayed_work(&hctx->delay_work, tmo);
 869         else {
 870                 unsigned int cpu;
 871
 872                 cpu = blk_mq_hctx_next_cpu(hctx);
 873                 kblockd_schedule_delayed_work_on(cpu, &hctx->delay_work, tmo);
 874         }
 875 }
 876 EXPORT_SYMBOL(blk_mq_delay_queue);
 877
 878 static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
 879                                     struct request *rq, bool at_head)
 880 {
 881         struct blk_mq_ctx *ctx = rq->mq_ctx;
 882
 883         trace_block_rq_insert(hctx->queue, rq);
 884
 885         if (at_head)
 886                 list_add(&rq->queuelist, &ctx->rq_list);
 887         else
 888                 list_add_tail(&rq->queuelist, &ctx->rq_list);
 889
 890         blk_mq_hctx_mark_pending(hctx, ctx);
 891
 892         /*
 893          * We do this early, to ensure we are on the right CPU.
 894          */
 895         blk_add_timer(rq);
 896 }
 897
 898 void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
 899                 bool async)
 900 {
 901         struct request_queue *q = rq->q;
 902         struct blk_mq_hw_ctx *hctx;
 903         struct blk_mq_ctx *ctx = rq->mq_ctx, *current_ctx;
 904
 905         current_ctx = blk_mq_get_ctx(q);
 906         if (!cpu_online(ctx->cpu))
 907                 rq->mq_ctx = ctx = current_ctx;
 908
 909         hctx = q->mq_ops->map_queue(q, ctx->cpu);
 910
 911         if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA) &&
 912             !(rq->cmd_flags & (REQ_FLUSH_SEQ))) {
 913                 blk_insert_flush(rq);
 914         } else {
 915                 spin_lock(&ctx->lock);
 916                 __blk_mq_insert_request(hctx, rq, at_head);
 917                 spin_unlock(&ctx->lock);
 918         }
 919
 920         if (run_queue)
 921                 blk_mq_run_hw_queue(hctx, async);
 922
 923         blk_mq_put_ctx(current_ctx);
 924 }
 925
 926 static void blk_mq_insert_requests(struct request_queue *q,
 927                                      struct blk_mq_ctx *ctx,
 928                                      struct list_head *list,
 929                                      int depth,
 930                                      bool from_schedule)
 931
 932 {
 933         struct blk_mq_hw_ctx *hctx;
 934         struct blk_mq_ctx *current_ctx;
 935
 936         trace_block_unplug(q, depth, !from_schedule);
 937
 938         current_ctx = blk_mq_get_ctx(q);
 939
 940         if (!cpu_online(ctx->cpu))
 941                 ctx = current_ctx;
 942         hctx = q->mq_ops->map_queue(q, ctx->cpu);
 943
 944         /*
 945          * preemption doesn't flush plug list, so it's possible ctx->cpu is
 946          * offline now
 947          */
 948         spin_lock(&ctx->lock);
 949         while (!list_empty(list)) {
 950                 struct request *rq;
 951
 952                 rq = list_first_entry(list, struct request, queuelist);
 953                 list_del_init(&rq->queuelist);
 954                 rq->mq_ctx = ctx;
 955                 __blk_mq_insert_request(hctx, rq, false);
 956         }
 957         spin_unlock(&ctx->lock);
 958
 959         blk_mq_run_hw_queue(hctx, from_schedule);
 960         blk_mq_put_ctx(current_ctx);
 961 }
 962
 963 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
 964 {
 965         struct request *rqa = container_of(a, struct request, queuelist);
 966         struct request *rqb = container_of(b, struct request, queuelist);
 967
 968         return !(rqa->mq_ctx < rqb->mq_ctx ||
 969                  (rqa->mq_ctx == rqb->mq_ctx &&
 970                   blk_rq_pos(rqa) < blk_rq_pos(rqb)));
 971 }
 972
 973 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
 974 {
 975         struct blk_mq_ctx *this_ctx;
 976         struct request_queue *this_q;
 977         struct request *rq;
 978         LIST_HEAD(list);
 979         LIST_HEAD(ctx_list);
 980         unsigned int depth;
 981
 982         list_splice_init(&plug->mq_list, &list);
 983
 984         list_sort(NULL, &list, plug_ctx_cmp);
 985
 986         this_q = NULL;
 987         this_ctx = NULL;
 988         depth = 0;
 989
 990         while (!list_empty(&list)) {
 991                 rq = list_entry_rq(list.next);
 992                 list_del_init(&rq->queuelist);
 993                 BUG_ON(!rq->q);
 994                 if (rq->mq_ctx != this_ctx) {
 995                         if (this_ctx) {
 996                                 blk_mq_insert_requests(this_q, this_ctx,
 997                                                         &ctx_list, depth,
 998                                                         from_schedule);
 999                         }
1000
1001                         this_ctx = rq->mq_ctx;
1002                         this_q = rq->q;
1003                         depth = 0;
1004                 }
1005
1006                 depth++;
1007                 list_add_tail(&rq->queuelist, &ctx_list);
1008         }
1009
1010         /*
1011          * If 'this_ctx' is set, we know we have entries to complete
1012          * on 'ctx_list'. Do those.
1013          */
1014         if (this_ctx) {
1015                 blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
1016                                        from_schedule);
1017         }
1018 }
1019
1020 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1021 {
1022         init_request_from_bio(rq, bio);
1023         blk_account_io_start(rq, 1);
1024 }
1025
1026 static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
1027 {
1028         struct blk_mq_hw_ctx *hctx;
1029         struct blk_mq_ctx *ctx;
1030         const int is_sync = rw_is_sync(bio->bi_rw);
1031         const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
1032         int rw = bio_data_dir(bio);
1033         struct request *rq;
1034         unsigned int use_plug, request_count = 0;
1035
1036         /*
1037          * If we have multiple hardware queues, just go directly to
1038          * one of those for sync IO.
1039          */
1040         use_plug = !is_flush_fua && ((q->nr_hw_queues == 1) || !is_sync);
1041
1042         blk_queue_bounce(q, &bio);
1043
1044         if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
1045                 bio_endio(bio, -EIO);
1046                 return;
1047         }
1048
1049         if (use_plug && blk_attempt_plug_merge(q, bio, &request_count))
1050                 return;
1051
1052         if (blk_mq_queue_enter(q)) {
1053                 bio_endio(bio, -EIO);
1054                 return;
1055         }
1056
1057         ctx = blk_mq_get_ctx(q);
1058         hctx = q->mq_ops->map_queue(q, ctx->cpu);
1059
1060         if (is_sync)
1061                 rw |= REQ_SYNC;
1062         trace_block_getrq(q, bio, rw);
1063         rq = __blk_mq_alloc_request(hctx, ctx, GFP_ATOMIC, false);
1064         if (likely(rq))
1065                 blk_mq_rq_ctx_init(q, ctx, rq, rw);
1066         else {
1067                 blk_mq_put_ctx(ctx);
1068                 trace_block_sleeprq(q, bio, rw);
1069                 rq = blk_mq_alloc_request_pinned(q, rw, __GFP_WAIT|GFP_ATOMIC,
1070                                                         false);
1071                 ctx = rq->mq_ctx;
1072                 hctx = q->mq_ops->map_queue(q, ctx->cpu);
1073         }
1074
1075         hctx->queued++;
1076
1077         if (unlikely(is_flush_fua)) {
1078                 blk_mq_bio_to_request(rq, bio);
1079                 blk_insert_flush(rq);
1080                 goto run_queue;
1081         }
1082
1083         /*
1084          * A task plug currently exists. Since this is completely lockless,
1085          * utilize that to temporarily store requests until the task is
1086          * either done or scheduled away.
1087          */
1088         if (use_plug) {
1089                 struct blk_plug *plug = current->plug;
1090
1091                 if (plug) {
1092                         blk_mq_bio_to_request(rq, bio);
1093                         if (list_empty(&plug->mq_list))
1094                                 trace_block_plug(q);
1095                         else if (request_count >= BLK_MAX_REQUEST_COUNT) {
1096                                 blk_flush_plug_list(plug, false);
1097                                 trace_block_plug(q);
1098                         }
1099                         list_add_tail(&rq->queuelist, &plug->mq_list);
1100                         blk_mq_put_ctx(ctx);
1101                         return;
1102                 }
1103         }
1104
1105         if (!(hctx->flags & BLK_MQ_F_SHOULD_MERGE)) {
1106                 init_request_from_bio(rq, bio);
1107
1108                 spin_lock(&ctx->lock);
1109 insert_rq:
1110                 __blk_mq_insert_request(hctx, rq, false);
1111                 spin_unlock(&ctx->lock);
1112                 blk_account_io_start(rq, 1);
1113         } else {
1114                 spin_lock(&ctx->lock);
1115                 if (!blk_mq_attempt_merge(q, ctx, bio)) {
1116                         init_request_from_bio(rq, bio);
1117                         goto insert_rq;
1118                 }
1119
1120                 spin_unlock(&ctx->lock);
1121                 __blk_mq_free_request(hctx, ctx, rq);
1122         }
1123
1124
1125         /*
1126          * For a SYNC request, send it to the hardware immediately. For an
1127          * ASYNC request, just ensure that we run it later on. The latter
1128          * allows for merging opportunities and more efficient dispatching.
1129          */
1130 run_queue:
1131         blk_mq_run_hw_queue(hctx, !is_sync || is_flush_fua);
1132         blk_mq_put_ctx(ctx);
1133 }
1134
1135 /*
1136  * Default mapping to a software queue, since we use one per CPU.
1137  */
1138 struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q, const int cpu)
1139 {
1140         return q->queue_hw_ctx[q->mq_map[cpu]];
1141 }
1142 EXPORT_SYMBOL(blk_mq_map_queue);
1143
1144 struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_tag_set *set,
1145                                                    unsigned int hctx_index)
1146 {
1147         return kzalloc_node(sizeof(struct blk_mq_hw_ctx), GFP_KERNEL,
1148                                 set->numa_node);
1149 }
1150 EXPORT_SYMBOL(blk_mq_alloc_single_hw_queue);
1151
1152 void blk_mq_free_single_hw_queue(struct blk_mq_hw_ctx *hctx,
1153                                  unsigned int hctx_index)
1154 {
1155         kfree(hctx);
1156 }
1157 EXPORT_SYMBOL(blk_mq_free_single_hw_queue);
1158
1159 static void blk_mq_hctx_notify(void *data, unsigned long action,
1160                                unsigned int cpu)
1161 {
1162         struct blk_mq_hw_ctx *hctx = data;
1163         struct request_queue *q = hctx->queue;
1164         struct blk_mq_ctx *ctx;
1165         LIST_HEAD(tmp);
1166
1167         if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
1168                 return;
1169
1170         /*
1171          * Move ctx entries to new CPU, if this one is going away.
1172          */
1173         ctx = __blk_mq_get_ctx(q, cpu);
1174
1175         spin_lock(&ctx->lock);
1176         if (!list_empty(&ctx->rq_list)) {
1177                 list_splice_init(&ctx->rq_list, &tmp);
1178                 clear_bit(ctx->index_hw, hctx->ctx_map);
1179         }
1180         spin_unlock(&ctx->lock);
1181
1182         if (list_empty(&tmp))
1183                 return;
1184
1185         ctx = blk_mq_get_ctx(q);
1186         spin_lock(&ctx->lock);
1187
1188         while (!list_empty(&tmp)) {
1189                 struct request *rq;
1190
1191                 rq = list_first_entry(&tmp, struct request, queuelist);
1192                 rq->mq_ctx = ctx;
1193                 list_move_tail(&rq->queuelist, &ctx->rq_list);
1194         }
1195
1196         hctx = q->mq_ops->map_queue(q, ctx->cpu);
1197         blk_mq_hctx_mark_pending(hctx, ctx);
1198
1199         spin_unlock(&ctx->lock);
1200
1201         blk_mq_run_hw_queue(hctx, true);
1202         blk_mq_put_ctx(ctx);
1203 }
1204
1205 static void blk_mq_free_rq_map(struct blk_mq_tag_set *set,
1206                 struct blk_mq_tags *tags, unsigned int hctx_idx)
1207 {
1208         struct page *page;
1209
1210         if (tags->rqs && set->ops->exit_request) {
1211                 int i;
1212
1213                 for (i = 0; i < tags->nr_tags; i++) {
1214                         if (!tags->rqs[i])
1215                                 continue;
1216                         set->ops->exit_request(set->driver_data, tags->rqs[i],
1217                                                 hctx_idx, i);
1218                 }
1219         }
1220
1221         while (!list_empty(&tags->page_list)) {
1222                 page = list_first_entry(&tags->page_list, struct page, lru);
1223                 list_del_init(&page->lru);
1224                 __free_pages(page, page->private);
1225         }
1226
1227         kfree(tags->rqs);
1228
1229         blk_mq_free_tags(tags);
1230 }
1231
1232 static size_t order_to_size(unsigned int order)
1233 {
1234         return (size_t)PAGE_SIZE << order;
1235 }
1236
1237 static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
1238                 unsigned int hctx_idx)
1239 {
1240         struct blk_mq_tags *tags;
1241         unsigned int i, j, entries_per_page, max_order = 4;
1242         size_t rq_size, left;
1243
1244         tags = blk_mq_init_tags(set->queue_depth, set->reserved_tags,
1245                                 set->numa_node);
1246         if (!tags)
1247                 return NULL;
1248
1249         INIT_LIST_HEAD(&tags->page_list);
1250
1251         tags->rqs = kmalloc_node(set->queue_depth * sizeof(struct request *),
1252                                         GFP_KERNEL, set->numa_node);
1253         if (!tags->rqs) {
1254                 blk_mq_free_tags(tags);
1255                 return NULL;
1256         }
1257
1258         /*
1259          * rq_size is the size of the request plus driver payload, rounded
1260          * to the cacheline size
1261          */
1262         rq_size = round_up(sizeof(struct request) + set->cmd_size,
1263                                 cache_line_size());
1264         left = rq_size * set->queue_depth;
1265
1266         for (i = 0; i < set->queue_depth; ) {
1267                 int this_order = max_order;
1268                 struct page *page;
1269                 int to_do;
1270                 void *p;
1271
1272                 while (left < order_to_size(this_order - 1) && this_order)
1273                         this_order--;
1274
1275                 do {
1276                         page = alloc_pages_node(set->numa_node, GFP_KERNEL,
1277                                                 this_order);
1278                         if (page)
1279                                 break;
1280                         if (!this_order--)
1281                                 break;
1282                         if (order_to_size(this_order) < rq_size)
1283                                 break;
1284                 } while (1);
1285
1286                 if (!page)
1287                         goto fail;
1288
1289                 page->private = this_order;
1290                 list_add_tail(&page->lru, &tags->page_list);
1291
1292                 p = page_address(page);
1293                 entries_per_page = order_to_size(this_order) / rq_size;
1294                 to_do = min(entries_per_page, set->queue_depth - i);
1295                 left -= to_do * rq_size;
1296                 for (j = 0; j < to_do; j++) {
1297                         tags->rqs[i] = p;
1298                         if (set->ops->init_request) {
1299                                 if (set->ops->init_request(set->driver_data,
1300                                                 tags->rqs[i], hctx_idx, i,
1301                                                 set->numa_node))
1302                                         goto fail;
1303                         }
1304
1305                         p += rq_size;
1306                         i++;
1307                 }
1308         }
1309
1310         return tags;
1311
1312 fail:
1313         pr_warn("%s: failed to allocate requests\n", __func__);
1314         blk_mq_free_rq_map(set, tags, hctx_idx);
1315         return NULL;
1316 }
1317
1318 static int blk_mq_init_hw_queues(struct request_queue *q,
1319                 struct blk_mq_tag_set *set)
1320 {
1321         struct blk_mq_hw_ctx *hctx;
1322         unsigned int i, j;
1323
1324         /*
1325          * Initialize hardware queues
1326          */
1327         queue_for_each_hw_ctx(q, hctx, i) {
1328                 unsigned int num_maps;
1329                 int node;
1330
1331                 node = hctx->numa_node;
1332                 if (node == NUMA_NO_NODE)
1333                         node = hctx->numa_node = set->numa_node;
1334
1335                 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
1336                 INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
1337                 spin_lock_init(&hctx->lock);
1338                 INIT_LIST_HEAD(&hctx->dispatch);
1339                 hctx->queue = q;
1340                 hctx->queue_num = i;
1341                 hctx->flags = set->flags;
1342                 hctx->cmd_size = set->cmd_size;
1343
1344                 blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
1345                                                 blk_mq_hctx_notify, hctx);
1346                 blk_mq_register_cpu_notifier(&hctx->cpu_notifier);
1347
1348                 hctx->tags = set->tags[i];
1349
1350                 /*
1351                  * Allocate space for all possible cpus to avoid allocation in
1352                  * runtime
1353                  */
1354                 hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1355                                                 GFP_KERNEL, node);
1356                 if (!hctx->ctxs)
1357                         break;
1358
1359                 num_maps = ALIGN(nr_cpu_ids, BITS_PER_LONG) / BITS_PER_LONG;
1360                 hctx->ctx_map = kzalloc_node(num_maps * sizeof(unsigned long),
1361                                                 GFP_KERNEL, node);
1362                 if (!hctx->ctx_map)
1363                         break;
1364
1365                 hctx->nr_ctx_map = num_maps;
1366                 hctx->nr_ctx = 0;
1367
1368                 if (set->ops->init_hctx &&
1369                     set->ops->init_hctx(hctx, set->driver_data, i))
1370                         break;
1371         }
1372
1373         if (i == q->nr_hw_queues)
1374                 return 0;
1375
1376         /*
1377          * Init failed
1378          */
1379         queue_for_each_hw_ctx(q, hctx, j) {
1380                 if (i == j)
1381                         break;
1382
1383                 if (set->ops->exit_hctx)
1384                         set->ops->exit_hctx(hctx, j);
1385
1386                 blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1387                 kfree(hctx->ctxs);
1388                 kfree(hctx->ctx_map);
1389         }
1390
1391         return 1;
1392 }
1393
1394 static void blk_mq_init_cpu_queues(struct request_queue *q,
1395                                    unsigned int nr_hw_queues)
1396 {
1397         unsigned int i;
1398
1399         for_each_possible_cpu(i) {
1400                 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1401                 struct blk_mq_hw_ctx *hctx;
1402
1403                 memset(__ctx, 0, sizeof(*__ctx));
1404                 __ctx->cpu = i;
1405                 spin_lock_init(&__ctx->lock);
1406                 INIT_LIST_HEAD(&__ctx->rq_list);
1407                 __ctx->queue = q;
1408
1409                 /* If the cpu isn't online, the cpu is mapped to first hctx */
1410                 if (!cpu_online(i))
1411                         continue;
1412
1413                 hctx = q->mq_ops->map_queue(q, i);
1414                 cpumask_set_cpu(i, hctx->cpumask);
1415                 hctx->nr_ctx++;
1416
1417                 /*
1418                  * Set local node, IFF we have more than one hw queue. If
1419                  * not, we remain on the home node of the device
1420                  */
1421                 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
1422                         hctx->numa_node = cpu_to_node(i);
1423         }
1424 }
1425
1426 static void blk_mq_map_swqueue(struct request_queue *q)
1427 {
1428         unsigned int i;
1429         struct blk_mq_hw_ctx *hctx;
1430         struct blk_mq_ctx *ctx;
1431
1432         queue_for_each_hw_ctx(q, hctx, i) {
1433                 cpumask_clear(hctx->cpumask);
1434                 hctx->nr_ctx = 0;
1435         }
1436
1437         /*
1438          * Map software to hardware queues
1439          */
1440         queue_for_each_ctx(q, ctx, i) {
1441                 /* If the cpu isn't online, the cpu is mapped to first hctx */
1442                 if (!cpu_online(i))
1443                         continue;
1444
1445                 hctx = q->mq_ops->map_queue(q, i);
1446                 cpumask_set_cpu(i, hctx->cpumask);
1447                 ctx->index_hw = hctx->nr_ctx;
1448                 hctx->ctxs[hctx->nr_ctx++] = ctx;
1449         }
1450
1451         queue_for_each_hw_ctx(q, hctx, i) {
1452                 hctx->next_cpu = cpumask_first(hctx->cpumask);
1453                 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1454         }
1455 }
1456
1457 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set)
1458 {
1459         struct blk_mq_hw_ctx *hctx;
1460         struct request_queue *q;
1461         bool shared;
1462         int i;
1463
1464         if (set->tag_list.next == set->tag_list.prev)
1465                 shared = false;
1466         else
1467                 shared = true;
1468
1469         list_for_each_entry(q, &set->tag_list, tag_set_list) {
1470                 blk_mq_freeze_queue(q);
1471
1472                 queue_for_each_hw_ctx(q, hctx, i) {
1473                         if (shared)
1474                                 hctx->flags |= BLK_MQ_F_TAG_SHARED;
1475                         else
1476                                 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
1477                 }
1478                 blk_mq_unfreeze_queue(q);
1479         }
1480 }
1481
1482 static void blk_mq_del_queue_tag_set(struct request_queue *q)
1483 {
1484         struct blk_mq_tag_set *set = q->tag_set;
1485
1486         blk_mq_freeze_queue(q);
1487
1488         mutex_lock(&set->tag_list_lock);
1489         list_del_init(&q->tag_set_list);
1490         blk_mq_update_tag_set_depth(set);
1491         mutex_unlock(&set->tag_list_lock);
1492
1493         blk_mq_unfreeze_queue(q);
1494 }
1495
1496 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
1497                                      struct request_queue *q)
1498 {
1499         q->tag_set = set;
1500
1501         mutex_lock(&set->tag_list_lock);
1502         list_add_tail(&q->tag_set_list, &set->tag_list);
1503         blk_mq_update_tag_set_depth(set);
1504         mutex_unlock(&set->tag_list_lock);
1505 }
1506
1507 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
1508 {
1509         struct blk_mq_hw_ctx **hctxs;
1510         struct blk_mq_ctx *ctx;
1511         struct request_queue *q;
1512         int i;
1513
1514         ctx = alloc_percpu(struct blk_mq_ctx);
1515         if (!ctx)
1516                 return ERR_PTR(-ENOMEM);
1517
1518         hctxs = kmalloc_node(set->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
1519                         set->numa_node);
1520
1521         if (!hctxs)
1522                 goto err_percpu;
1523
1524         for (i = 0; i < set->nr_hw_queues; i++) {
1525                 hctxs[i] = set->ops->alloc_hctx(set, i);
1526                 if (!hctxs[i])
1527                         goto err_hctxs;
1528
1529                 if (!zalloc_cpumask_var(&hctxs[i]->cpumask, GFP_KERNEL))
1530                         goto err_hctxs;
1531
1532                 atomic_set(&hctxs[i]->nr_active, 0);
1533                 hctxs[i]->numa_node = NUMA_NO_NODE;
1534                 hctxs[i]->queue_num = i;
1535         }
1536
1537         q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
1538         if (!q)
1539                 goto err_hctxs;
1540
1541         q->mq_map = blk_mq_make_queue_map(set);
1542         if (!q->mq_map)
1543                 goto err_map;
1544
1545         setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
1546         blk_queue_rq_timeout(q, 30000);
1547
1548         q->nr_queues = nr_cpu_ids;
1549         q->nr_hw_queues = set->nr_hw_queues;
1550
1551         q->queue_ctx = ctx;
1552         q->queue_hw_ctx = hctxs;
1553
1554         q->mq_ops = set->ops;
1555         q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
1556
1557         q->sg_reserved_size = INT_MAX;
1558
1559         blk_queue_make_request(q, blk_mq_make_request);
1560         blk_queue_rq_timed_out(q, blk_mq_rq_timed_out);
1561         if (set->timeout)
1562                 blk_queue_rq_timeout(q, set->timeout);
1563
1564         if (set->ops->complete)
1565                 blk_queue_softirq_done(q, set->ops->complete);
1566
1567         blk_mq_init_flush(q);
1568         blk_mq_init_cpu_queues(q, set->nr_hw_queues);
1569
1570         q->flush_rq = kzalloc(round_up(sizeof(struct request) +
1571                                 set->cmd_size, cache_line_size()),
1572                                 GFP_KERNEL);
1573         if (!q->flush_rq)
1574                 goto err_hw;
1575
1576         if (blk_mq_init_hw_queues(q, set))
1577                 goto err_flush_rq;
1578
1579         blk_mq_map_swqueue(q);
1580
1581         mutex_lock(&all_q_mutex);
1582         list_add_tail(&q->all_q_node, &all_q_list);
1583         mutex_unlock(&all_q_mutex);
1584
1585         blk_mq_add_queue_tag_set(set, q);
1586
1587         return q;
1588
1589 err_flush_rq:
1590         kfree(q->flush_rq);
1591 err_hw:
1592         kfree(q->mq_map);
1593 err_map:
1594         blk_cleanup_queue(q);
1595 err_hctxs:
1596         for (i = 0; i < set->nr_hw_queues; i++) {
1597                 if (!hctxs[i])
1598                         break;
1599                 free_cpumask_var(hctxs[i]->cpumask);
1600                 set->ops->free_hctx(hctxs[i], i);
1601         }
1602         kfree(hctxs);
1603 err_percpu:
1604         free_percpu(ctx);
1605         return ERR_PTR(-ENOMEM);
1606 }
1607 EXPORT_SYMBOL(blk_mq_init_queue);
1608
1609 void blk_mq_free_queue(struct request_queue *q)
1610 {
1611         struct blk_mq_hw_ctx *hctx;
1612         int i;
1613
1614         blk_mq_del_queue_tag_set(q);
1615
1616         queue_for_each_hw_ctx(q, hctx, i) {
1617                 kfree(hctx->ctx_map);
1618                 kfree(hctx->ctxs);
1619                 blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1620                 if (q->mq_ops->exit_hctx)
1621                         q->mq_ops->exit_hctx(hctx, i);
1622                 free_cpumask_var(hctx->cpumask);
1623                 q->mq_ops->free_hctx(hctx, i);
1624         }
1625
1626         free_percpu(q->queue_ctx);
1627         kfree(q->queue_hw_ctx);
1628         kfree(q->mq_map);
1629
1630         q->queue_ctx = NULL;
1631         q->queue_hw_ctx = NULL;
1632         q->mq_map = NULL;
1633
1634         mutex_lock(&all_q_mutex);
1635         list_del_init(&q->all_q_node);
1636         mutex_unlock(&all_q_mutex);
1637 }
1638
1639 /* Basically redo blk_mq_init_queue with queue frozen */
1640 static void blk_mq_queue_reinit(struct request_queue *q)
1641 {
1642         blk_mq_freeze_queue(q);
1643
1644         blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues);
1645
1646         /*
1647          * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
1648          * we should change hctx numa_node according to new topology (this
1649          * involves free and re-allocate memory, worthy doing?)
1650          */
1651
1652         blk_mq_map_swqueue(q);
1653
1654         blk_mq_unfreeze_queue(q);
1655 }
1656
1657 static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
1658                                       unsigned long action, void *hcpu)
1659 {
1660         struct request_queue *q;
1661
1662         /*
1663          * Before new mappings are established, hotadded cpu might already
1664          * start handling requests. This doesn't break anything as we map
1665          * offline CPUs to first hardware queue. We will re-init the queue
1666          * below to get optimal settings.
1667          */
1668         if (action != CPU_DEAD && action != CPU_DEAD_FROZEN &&
1669             action != CPU_ONLINE && action != CPU_ONLINE_FROZEN)
1670                 return NOTIFY_OK;
1671
1672         mutex_lock(&all_q_mutex);
1673         list_for_each_entry(q, &all_q_list, all_q_node)
1674                 blk_mq_queue_reinit(q);
1675         mutex_unlock(&all_q_mutex);
1676         return NOTIFY_OK;
1677 }
1678
1679 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
1680 {
1681         int i;
1682
1683         if (!set->nr_hw_queues)
1684                 return -EINVAL;
1685         if (!set->queue_depth || set->queue_depth > BLK_MQ_MAX_DEPTH)
1686                 return -EINVAL;
1687         if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
1688                 return -EINVAL;
1689
1690         if (!set->nr_hw_queues ||
1691             !set->ops->queue_rq || !set->ops->map_queue ||
1692             !set->ops->alloc_hctx || !set->ops->free_hctx)
1693                 return -EINVAL;
1694
1695
1696         set->tags = kmalloc_node(set->nr_hw_queues *
1697                                  sizeof(struct blk_mq_tags *),
1698                                  GFP_KERNEL, set->numa_node);
1699         if (!set->tags)
1700                 goto out;
1701
1702         for (i = 0; i < set->nr_hw_queues; i++) {
1703                 set->tags[i] = blk_mq_init_rq_map(set, i);
1704                 if (!set->tags[i])
1705                         goto out_unwind;
1706         }
1707
1708         mutex_init(&set->tag_list_lock);
1709         INIT_LIST_HEAD(&set->tag_list);
1710
1711         return 0;
1712
1713 out_unwind:
1714         while (--i >= 0)
1715                 blk_mq_free_rq_map(set, set->tags[i], i);
1716 out:
1717         return -ENOMEM;
1718 }
1719 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
1720
1721 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
1722 {
1723         int i;
1724
1725         for (i = 0; i < set->nr_hw_queues; i++)
1726                 blk_mq_free_rq_map(set, set->tags[i], i);
1727         kfree(set->tags);
1728 }
1729 EXPORT_SYMBOL(blk_mq_free_tag_set);
1730
1731 void blk_mq_disable_hotplug(void)
1732 {
1733         mutex_lock(&all_q_mutex);
1734 }
1735
1736 void blk_mq_enable_hotplug(void)
1737 {
1738         mutex_unlock(&all_q_mutex);
1739 }
1740
1741 static int __init blk_mq_init(void)
1742 {
1743         blk_mq_cpu_init();
1744
1745         /* Must be called after percpu_counter_hotcpu_callback() */
1746         hotcpu_notifier(blk_mq_queue_reinit_notify, -10);
1747
1748         return 0;
1749 }
1750 subsys_initcall(blk_mq_init);