2 * Block multiqueue core code
4 * Copyright (C) 2013-2014 Jens Axboe
5 * Copyright (C) 2013-2014 Christoph Hellwig
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/backing-dev.h>
10 #include <linux/bio.h>
11 #include <linux/blkdev.h>
12 #include <linux/kmemleak.h>
14 #include <linux/init.h>
15 #include <linux/slab.h>
16 #include <linux/workqueue.h>
17 #include <linux/smp.h>
18 #include <linux/llist.h>
19 #include <linux/list_sort.h>
20 #include <linux/cpu.h>
21 #include <linux/cache.h>
22 #include <linux/sched/sysctl.h>
23 #include <linux/sched/topology.h>
24 #include <linux/sched/signal.h>
25 #include <linux/delay.h>
26 #include <linux/crash_dump.h>
27 #include <linux/prefetch.h>
29 #include <trace/events/block.h>
31 #include <linux/blk-mq.h>
34 #include "blk-mq-debugfs.h"
35 #include "blk-mq-tag.h"
38 #include "blk-mq-sched.h"
40 static void blk_mq_poll_stats_start(struct request_queue *q);
41 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
43 static int blk_mq_poll_stats_bkt(const struct request *rq)
45 int ddir, bytes, bucket;
47 ddir = rq_data_dir(rq);
48 bytes = blk_rq_bytes(rq);
50 bucket = ddir + 2*(ilog2(bytes) - 9);
54 else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
55 return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
61 * Check if any of the ctx's have pending work in this hardware queue
63 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
65 return sbitmap_any_bit_set(&hctx->ctx_map) ||
66 !list_empty_careful(&hctx->dispatch) ||
67 blk_mq_sched_has_work(hctx);
71 * Mark this ctx as having pending work in this hardware queue
73 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
74 struct blk_mq_ctx *ctx)
76 if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
77 sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
80 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
81 struct blk_mq_ctx *ctx)
83 sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
86 void blk_freeze_queue_start(struct request_queue *q)
90 freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
91 if (freeze_depth == 1) {
92 percpu_ref_kill(&q->q_usage_counter);
93 blk_mq_run_hw_queues(q, false);
96 EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
98 void blk_mq_freeze_queue_wait(struct request_queue *q)
100 wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
102 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
104 int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
105 unsigned long timeout)
107 return wait_event_timeout(q->mq_freeze_wq,
108 percpu_ref_is_zero(&q->q_usage_counter),
111 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
114 * Guarantee no request is in use, so we can change any data structure of
115 * the queue afterward.
117 void blk_freeze_queue(struct request_queue *q)
120 * In the !blk_mq case we are only calling this to kill the
121 * q_usage_counter, otherwise this increases the freeze depth
122 * and waits for it to return to zero. For this reason there is
123 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
124 * exported to drivers as the only user for unfreeze is blk_mq.
126 blk_freeze_queue_start(q);
127 blk_mq_freeze_queue_wait(q);
130 void blk_mq_freeze_queue(struct request_queue *q)
133 * ...just an alias to keep freeze and unfreeze actions balanced
134 * in the blk_mq_* namespace
138 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
140 void blk_mq_unfreeze_queue(struct request_queue *q)
144 freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
145 WARN_ON_ONCE(freeze_depth < 0);
147 percpu_ref_reinit(&q->q_usage_counter);
148 wake_up_all(&q->mq_freeze_wq);
151 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
154 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
155 * mpt3sas driver such that this function can be removed.
157 void blk_mq_quiesce_queue_nowait(struct request_queue *q)
161 spin_lock_irqsave(q->queue_lock, flags);
162 queue_flag_set(QUEUE_FLAG_QUIESCED, q);
163 spin_unlock_irqrestore(q->queue_lock, flags);
165 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
168 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
171 * Note: this function does not prevent that the struct request end_io()
172 * callback function is invoked. Once this function is returned, we make
173 * sure no dispatch can happen until the queue is unquiesced via
174 * blk_mq_unquiesce_queue().
176 void blk_mq_quiesce_queue(struct request_queue *q)
178 struct blk_mq_hw_ctx *hctx;
182 blk_mq_quiesce_queue_nowait(q);
184 queue_for_each_hw_ctx(q, hctx, i) {
185 if (hctx->flags & BLK_MQ_F_BLOCKING)
186 synchronize_srcu(hctx->queue_rq_srcu);
193 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
196 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
199 * This function recovers queue into the state before quiescing
200 * which is done by blk_mq_quiesce_queue.
202 void blk_mq_unquiesce_queue(struct request_queue *q)
206 spin_lock_irqsave(q->queue_lock, flags);
207 queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
208 spin_unlock_irqrestore(q->queue_lock, flags);
210 /* dispatch requests which are inserted during quiescing */
211 blk_mq_run_hw_queues(q, true);
213 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue);
215 void blk_mq_wake_waiters(struct request_queue *q)
217 struct blk_mq_hw_ctx *hctx;
220 queue_for_each_hw_ctx(q, hctx, i)
221 if (blk_mq_hw_queue_mapped(hctx))
222 blk_mq_tag_wakeup_all(hctx->tags, true);
225 * If we are called because the queue has now been marked as
226 * dying, we need to ensure that processes currently waiting on
227 * the queue are notified as well.
229 wake_up_all(&q->mq_freeze_wq);
232 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
234 return blk_mq_has_free_tags(hctx->tags);
236 EXPORT_SYMBOL(blk_mq_can_queue);
238 static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
239 unsigned int tag, unsigned int op)
241 struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
242 struct request *rq = tags->static_rqs[tag];
246 if (data->flags & BLK_MQ_REQ_INTERNAL) {
248 rq->internal_tag = tag;
250 if (blk_mq_tag_busy(data->hctx)) {
251 rq->rq_flags = RQF_MQ_INFLIGHT;
252 atomic_inc(&data->hctx->nr_active);
255 rq->internal_tag = -1;
256 data->hctx->tags->rqs[rq->tag] = rq;
259 INIT_LIST_HEAD(&rq->queuelist);
260 /* csd/requeue_work/fifo_time is initialized before use */
262 rq->mq_ctx = data->ctx;
264 if (blk_queue_io_stat(data->q))
265 rq->rq_flags |= RQF_IO_STAT;
266 /* do not touch atomic flags, it needs atomic ops against the timer */
268 INIT_HLIST_NODE(&rq->hash);
269 RB_CLEAR_NODE(&rq->rb_node);
272 rq->start_time = jiffies;
273 #ifdef CONFIG_BLK_CGROUP
275 set_start_time_ns(rq);
276 rq->io_start_time_ns = 0;
278 rq->nr_phys_segments = 0;
279 #if defined(CONFIG_BLK_DEV_INTEGRITY)
280 rq->nr_integrity_segments = 0;
283 /* tag was already set */
286 INIT_LIST_HEAD(&rq->timeout_list);
290 rq->end_io_data = NULL;
293 data->ctx->rq_dispatched[op_is_sync(op)]++;
297 static struct request *blk_mq_get_request(struct request_queue *q,
298 struct bio *bio, unsigned int op,
299 struct blk_mq_alloc_data *data)
301 struct elevator_queue *e = q->elevator;
304 struct blk_mq_ctx *local_ctx = NULL;
306 blk_queue_enter_live(q);
308 if (likely(!data->ctx))
309 data->ctx = local_ctx = blk_mq_get_ctx(q);
310 if (likely(!data->hctx))
311 data->hctx = blk_mq_map_queue(q, data->ctx->cpu);
313 data->flags |= BLK_MQ_REQ_NOWAIT;
316 data->flags |= BLK_MQ_REQ_INTERNAL;
319 * Flush requests are special and go directly to the
322 if (!op_is_flush(op) && e->type->ops.mq.limit_depth)
323 e->type->ops.mq.limit_depth(op, data);
326 tag = blk_mq_get_tag(data);
327 if (tag == BLK_MQ_TAG_FAIL) {
329 blk_mq_put_ctx(local_ctx);
336 rq = blk_mq_rq_ctx_init(data, tag, op);
337 if (!op_is_flush(op)) {
339 if (e && e->type->ops.mq.prepare_request) {
340 if (e->type->icq_cache && rq_ioc(bio))
341 blk_mq_sched_assign_ioc(rq, bio);
343 e->type->ops.mq.prepare_request(rq, bio);
344 rq->rq_flags |= RQF_ELVPRIV;
347 data->hctx->queued++;
351 struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
354 struct blk_mq_alloc_data alloc_data = { .flags = flags };
358 ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
362 rq = blk_mq_get_request(q, NULL, op, &alloc_data);
365 return ERR_PTR(-EWOULDBLOCK);
367 blk_mq_put_ctx(alloc_data.ctx);
371 rq->__sector = (sector_t) -1;
372 rq->bio = rq->biotail = NULL;
375 EXPORT_SYMBOL(blk_mq_alloc_request);
377 struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
378 unsigned int op, unsigned int flags, unsigned int hctx_idx)
380 struct blk_mq_alloc_data alloc_data = { .flags = flags };
386 * If the tag allocator sleeps we could get an allocation for a
387 * different hardware context. No need to complicate the low level
388 * allocator for this for the rare use case of a command tied to
391 if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
392 return ERR_PTR(-EINVAL);
394 if (hctx_idx >= q->nr_hw_queues)
395 return ERR_PTR(-EIO);
397 ret = blk_queue_enter(q, true);
402 * Check if the hardware context is actually mapped to anything.
403 * If not tell the caller that it should skip this queue.
405 alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
406 if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
408 return ERR_PTR(-EXDEV);
410 cpu = cpumask_first(alloc_data.hctx->cpumask);
411 alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
413 rq = blk_mq_get_request(q, NULL, op, &alloc_data);
416 return ERR_PTR(-EWOULDBLOCK);
422 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
424 void blk_mq_free_request(struct request *rq)
426 struct request_queue *q = rq->q;
427 struct elevator_queue *e = q->elevator;
428 struct blk_mq_ctx *ctx = rq->mq_ctx;
429 struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
430 const int sched_tag = rq->internal_tag;
432 if (rq->rq_flags & RQF_ELVPRIV) {
433 if (e && e->type->ops.mq.finish_request)
434 e->type->ops.mq.finish_request(rq);
436 put_io_context(rq->elv.icq->ioc);
441 ctx->rq_completed[rq_is_sync(rq)]++;
442 if (rq->rq_flags & RQF_MQ_INFLIGHT)
443 atomic_dec(&hctx->nr_active);
445 wbt_done(q->rq_wb, &rq->issue_stat);
447 clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
448 clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
450 blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
452 blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag);
453 blk_mq_sched_restart(hctx);
456 EXPORT_SYMBOL_GPL(blk_mq_free_request);
458 inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
460 blk_account_io_done(rq);
463 wbt_done(rq->q->rq_wb, &rq->issue_stat);
464 rq->end_io(rq, error);
466 if (unlikely(blk_bidi_rq(rq)))
467 blk_mq_free_request(rq->next_rq);
468 blk_mq_free_request(rq);
471 EXPORT_SYMBOL(__blk_mq_end_request);
473 void blk_mq_end_request(struct request *rq, blk_status_t error)
475 if (blk_update_request(rq, error, blk_rq_bytes(rq)))
477 __blk_mq_end_request(rq, error);
479 EXPORT_SYMBOL(blk_mq_end_request);
481 static void __blk_mq_complete_request_remote(void *data)
483 struct request *rq = data;
485 rq->q->softirq_done_fn(rq);
488 static void __blk_mq_complete_request(struct request *rq)
490 struct blk_mq_ctx *ctx = rq->mq_ctx;
494 if (rq->internal_tag != -1)
495 blk_mq_sched_completed_request(rq);
496 if (rq->rq_flags & RQF_STATS) {
497 blk_mq_poll_stats_start(rq->q);
501 if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
502 rq->q->softirq_done_fn(rq);
507 if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
508 shared = cpus_share_cache(cpu, ctx->cpu);
510 if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
511 rq->csd.func = __blk_mq_complete_request_remote;
514 smp_call_function_single_async(ctx->cpu, &rq->csd);
516 rq->q->softirq_done_fn(rq);
522 * blk_mq_complete_request - end I/O on a request
523 * @rq: the request being processed
526 * Ends all I/O on a request. It does not handle partial completions.
527 * The actual completion happens out-of-order, through a IPI handler.
529 void blk_mq_complete_request(struct request *rq)
531 struct request_queue *q = rq->q;
533 if (unlikely(blk_should_fake_timeout(q)))
535 if (!blk_mark_rq_complete(rq))
536 __blk_mq_complete_request(rq);
538 EXPORT_SYMBOL(blk_mq_complete_request);
540 int blk_mq_request_started(struct request *rq)
542 return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
544 EXPORT_SYMBOL_GPL(blk_mq_request_started);
546 void blk_mq_start_request(struct request *rq)
548 struct request_queue *q = rq->q;
550 blk_mq_sched_started_request(rq);
552 trace_block_rq_issue(q, rq);
554 if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
555 blk_stat_set_issue(&rq->issue_stat, blk_rq_sectors(rq));
556 rq->rq_flags |= RQF_STATS;
557 wbt_issue(q->rq_wb, &rq->issue_stat);
563 * Ensure that ->deadline is visible before set the started
564 * flag and clear the completed flag.
566 smp_mb__before_atomic();
569 * Mark us as started and clear complete. Complete might have been
570 * set if requeue raced with timeout, which then marked it as
571 * complete. So be sure to clear complete again when we start
572 * the request, otherwise we'll ignore the completion event.
574 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
575 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
576 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
577 clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
579 if (q->dma_drain_size && blk_rq_bytes(rq)) {
581 * Make sure space for the drain appears. We know we can do
582 * this because max_hw_segments has been adjusted to be one
583 * fewer than the device can handle.
585 rq->nr_phys_segments++;
588 EXPORT_SYMBOL(blk_mq_start_request);
591 * When we reach here because queue is busy, REQ_ATOM_COMPLETE
592 * flag isn't set yet, so there may be race with timeout handler,
593 * but given rq->deadline is just set in .queue_rq() under
594 * this situation, the race won't be possible in reality because
595 * rq->timeout should be set as big enough to cover the window
596 * between blk_mq_start_request() called from .queue_rq() and
597 * clearing REQ_ATOM_STARTED here.
599 static void __blk_mq_requeue_request(struct request *rq)
601 struct request_queue *q = rq->q;
603 trace_block_rq_requeue(q, rq);
604 wbt_requeue(q->rq_wb, &rq->issue_stat);
605 blk_mq_sched_requeue_request(rq);
607 if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
608 if (q->dma_drain_size && blk_rq_bytes(rq))
609 rq->nr_phys_segments--;
613 void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
615 __blk_mq_requeue_request(rq);
617 BUG_ON(blk_queued_rq(rq));
618 blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
620 EXPORT_SYMBOL(blk_mq_requeue_request);
622 static void blk_mq_requeue_work(struct work_struct *work)
624 struct request_queue *q =
625 container_of(work, struct request_queue, requeue_work.work);
627 struct request *rq, *next;
630 spin_lock_irqsave(&q->requeue_lock, flags);
631 list_splice_init(&q->requeue_list, &rq_list);
632 spin_unlock_irqrestore(&q->requeue_lock, flags);
634 list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
635 if (!(rq->rq_flags & RQF_SOFTBARRIER))
638 rq->rq_flags &= ~RQF_SOFTBARRIER;
639 list_del_init(&rq->queuelist);
640 blk_mq_sched_insert_request(rq, true, false, false, true);
643 while (!list_empty(&rq_list)) {
644 rq = list_entry(rq_list.next, struct request, queuelist);
645 list_del_init(&rq->queuelist);
646 blk_mq_sched_insert_request(rq, false, false, false, true);
649 blk_mq_run_hw_queues(q, false);
652 void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
653 bool kick_requeue_list)
655 struct request_queue *q = rq->q;
659 * We abuse this flag that is otherwise used by the I/O scheduler to
660 * request head insertation from the workqueue.
662 BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
664 spin_lock_irqsave(&q->requeue_lock, flags);
666 rq->rq_flags |= RQF_SOFTBARRIER;
667 list_add(&rq->queuelist, &q->requeue_list);
669 list_add_tail(&rq->queuelist, &q->requeue_list);
671 spin_unlock_irqrestore(&q->requeue_lock, flags);
673 if (kick_requeue_list)
674 blk_mq_kick_requeue_list(q);
676 EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
678 void blk_mq_kick_requeue_list(struct request_queue *q)
680 kblockd_schedule_delayed_work(&q->requeue_work, 0);
682 EXPORT_SYMBOL(blk_mq_kick_requeue_list);
684 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
687 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
688 msecs_to_jiffies(msecs));
690 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
692 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
694 if (tag < tags->nr_tags) {
695 prefetch(tags->rqs[tag]);
696 return tags->rqs[tag];
701 EXPORT_SYMBOL(blk_mq_tag_to_rq);
703 struct blk_mq_timeout_data {
705 unsigned int next_set;
708 void blk_mq_rq_timed_out(struct request *req, bool reserved)
710 const struct blk_mq_ops *ops = req->q->mq_ops;
711 enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
714 * We know that complete is set at this point. If STARTED isn't set
715 * anymore, then the request isn't active and the "timeout" should
716 * just be ignored. This can happen due to the bitflag ordering.
717 * Timeout first checks if STARTED is set, and if it is, assumes
718 * the request is active. But if we race with completion, then
719 * both flags will get cleared. So check here again, and ignore
720 * a timeout event with a request that isn't active.
722 if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
726 ret = ops->timeout(req, reserved);
730 __blk_mq_complete_request(req);
732 case BLK_EH_RESET_TIMER:
734 blk_clear_rq_complete(req);
736 case BLK_EH_NOT_HANDLED:
739 printk(KERN_ERR "block: bad eh return: %d\n", ret);
744 static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
745 struct request *rq, void *priv, bool reserved)
747 struct blk_mq_timeout_data *data = priv;
749 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
753 * The rq being checked may have been freed and reallocated
754 * out already here, we avoid this race by checking rq->deadline
755 * and REQ_ATOM_COMPLETE flag together:
757 * - if rq->deadline is observed as new value because of
758 * reusing, the rq won't be timed out because of timing.
759 * - if rq->deadline is observed as previous value,
760 * REQ_ATOM_COMPLETE flag won't be cleared in reuse path
761 * because we put a barrier between setting rq->deadline
762 * and clearing the flag in blk_mq_start_request(), so
763 * this rq won't be timed out too.
765 if (time_after_eq(jiffies, rq->deadline)) {
766 if (!blk_mark_rq_complete(rq))
767 blk_mq_rq_timed_out(rq, reserved);
768 } else if (!data->next_set || time_after(data->next, rq->deadline)) {
769 data->next = rq->deadline;
774 static void blk_mq_timeout_work(struct work_struct *work)
776 struct request_queue *q =
777 container_of(work, struct request_queue, timeout_work);
778 struct blk_mq_timeout_data data = {
784 /* A deadlock might occur if a request is stuck requiring a
785 * timeout at the same time a queue freeze is waiting
786 * completion, since the timeout code would not be able to
787 * acquire the queue reference here.
789 * That's why we don't use blk_queue_enter here; instead, we use
790 * percpu_ref_tryget directly, because we need to be able to
791 * obtain a reference even in the short window between the queue
792 * starting to freeze, by dropping the first reference in
793 * blk_freeze_queue_start, and the moment the last request is
794 * consumed, marked by the instant q_usage_counter reaches
797 if (!percpu_ref_tryget(&q->q_usage_counter))
800 blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
803 data.next = blk_rq_timeout(round_jiffies_up(data.next));
804 mod_timer(&q->timeout, data.next);
806 struct blk_mq_hw_ctx *hctx;
808 queue_for_each_hw_ctx(q, hctx, i) {
809 /* the hctx may be unmapped, so check it here */
810 if (blk_mq_hw_queue_mapped(hctx))
811 blk_mq_tag_idle(hctx);
817 struct flush_busy_ctx_data {
818 struct blk_mq_hw_ctx *hctx;
819 struct list_head *list;
822 static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
824 struct flush_busy_ctx_data *flush_data = data;
825 struct blk_mq_hw_ctx *hctx = flush_data->hctx;
826 struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
828 sbitmap_clear_bit(sb, bitnr);
829 spin_lock(&ctx->lock);
830 list_splice_tail_init(&ctx->rq_list, flush_data->list);
831 spin_unlock(&ctx->lock);
836 * Process software queues that have been marked busy, splicing them
837 * to the for-dispatch
839 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
841 struct flush_busy_ctx_data data = {
846 sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
848 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
850 static inline unsigned int queued_to_index(unsigned int queued)
855 return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
858 bool blk_mq_get_driver_tag(struct request *rq, struct blk_mq_hw_ctx **hctx,
861 struct blk_mq_alloc_data data = {
863 .hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
864 .flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
867 might_sleep_if(wait);
872 if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
873 data.flags |= BLK_MQ_REQ_RESERVED;
875 rq->tag = blk_mq_get_tag(&data);
877 if (blk_mq_tag_busy(data.hctx)) {
878 rq->rq_flags |= RQF_MQ_INFLIGHT;
879 atomic_inc(&data.hctx->nr_active);
881 data.hctx->tags->rqs[rq->tag] = rq;
887 return rq->tag != -1;
890 static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
893 blk_mq_put_tag(hctx, hctx->tags, rq->mq_ctx, rq->tag);
896 if (rq->rq_flags & RQF_MQ_INFLIGHT) {
897 rq->rq_flags &= ~RQF_MQ_INFLIGHT;
898 atomic_dec(&hctx->nr_active);
902 static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx *hctx,
905 if (rq->tag == -1 || rq->internal_tag == -1)
908 __blk_mq_put_driver_tag(hctx, rq);
911 static void blk_mq_put_driver_tag(struct request *rq)
913 struct blk_mq_hw_ctx *hctx;
915 if (rq->tag == -1 || rq->internal_tag == -1)
918 hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu);
919 __blk_mq_put_driver_tag(hctx, rq);
923 * If we fail getting a driver tag because all the driver tags are already
924 * assigned and on the dispatch list, BUT the first entry does not have a
925 * tag, then we could deadlock. For that case, move entries with assigned
926 * driver tags to the front, leaving the set of tagged requests in the
927 * same order, and the untagged set in the same order.
929 static bool reorder_tags_to_front(struct list_head *list)
931 struct request *rq, *tmp, *first = NULL;
933 list_for_each_entry_safe_reverse(rq, tmp, list, queuelist) {
937 list_move(&rq->queuelist, list);
943 return first != NULL;
946 static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode, int flags,
949 struct blk_mq_hw_ctx *hctx;
951 hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
953 list_del(&wait->entry);
954 clear_bit_unlock(BLK_MQ_S_TAG_WAITING, &hctx->state);
955 blk_mq_run_hw_queue(hctx, true);
959 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx *hctx)
961 struct sbq_wait_state *ws;
964 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
965 * The thread which wins the race to grab this bit adds the hardware
966 * queue to the wait queue.
968 if (test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state) ||
969 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING, &hctx->state))
972 init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
973 ws = bt_wait_ptr(&hctx->tags->bitmap_tags, hctx);
976 * As soon as this returns, it's no longer safe to fiddle with
977 * hctx->dispatch_wait, since a completion can wake up the wait queue
978 * and unlock the bit.
980 add_wait_queue(&ws->wait, &hctx->dispatch_wait);
984 bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list)
986 struct blk_mq_hw_ctx *hctx;
990 if (list_empty(list))
994 * Now process all the entries, sending them to the driver.
998 struct blk_mq_queue_data bd;
1001 rq = list_first_entry(list, struct request, queuelist);
1002 if (!blk_mq_get_driver_tag(rq, &hctx, false)) {
1003 if (!queued && reorder_tags_to_front(list))
1007 * The initial allocation attempt failed, so we need to
1008 * rerun the hardware queue when a tag is freed.
1010 if (!blk_mq_dispatch_wait_add(hctx))
1014 * It's possible that a tag was freed in the window
1015 * between the allocation failure and adding the
1016 * hardware queue to the wait queue.
1018 if (!blk_mq_get_driver_tag(rq, &hctx, false))
1022 list_del_init(&rq->queuelist);
1027 * Flag last if we have no more requests, or if we have more
1028 * but can't assign a driver tag to it.
1030 if (list_empty(list))
1033 struct request *nxt;
1035 nxt = list_first_entry(list, struct request, queuelist);
1036 bd.last = !blk_mq_get_driver_tag(nxt, NULL, false);
1039 ret = q->mq_ops->queue_rq(hctx, &bd);
1040 if (ret == BLK_STS_RESOURCE) {
1041 blk_mq_put_driver_tag_hctx(hctx, rq);
1042 list_add(&rq->queuelist, list);
1043 __blk_mq_requeue_request(rq);
1047 if (unlikely(ret != BLK_STS_OK)) {
1049 blk_mq_end_request(rq, BLK_STS_IOERR);
1054 } while (!list_empty(list));
1056 hctx->dispatched[queued_to_index(queued)]++;
1059 * Any items that need requeuing? Stuff them into hctx->dispatch,
1060 * that is where we will continue on next queue run.
1062 if (!list_empty(list)) {
1064 * If an I/O scheduler has been configured and we got a driver
1065 * tag for the next request already, free it again.
1067 rq = list_first_entry(list, struct request, queuelist);
1068 blk_mq_put_driver_tag(rq);
1070 spin_lock(&hctx->lock);
1071 list_splice_init(list, &hctx->dispatch);
1072 spin_unlock(&hctx->lock);
1075 * If SCHED_RESTART was set by the caller of this function and
1076 * it is no longer set that means that it was cleared by another
1077 * thread and hence that a queue rerun is needed.
1079 * If TAG_WAITING is set that means that an I/O scheduler has
1080 * been configured and another thread is waiting for a driver
1081 * tag. To guarantee fairness, do not rerun this hardware queue
1082 * but let the other thread grab the driver tag.
1084 * If no I/O scheduler has been configured it is possible that
1085 * the hardware queue got stopped and restarted before requests
1086 * were pushed back onto the dispatch list. Rerun the queue to
1087 * avoid starvation. Notes:
1088 * - blk_mq_run_hw_queue() checks whether or not a queue has
1089 * been stopped before rerunning a queue.
1090 * - Some but not all block drivers stop a queue before
1091 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1094 if (!blk_mq_sched_needs_restart(hctx) &&
1095 !test_bit(BLK_MQ_S_TAG_WAITING, &hctx->state))
1096 blk_mq_run_hw_queue(hctx, true);
1099 return (queued + errors) != 0;
1102 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
1106 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
1107 cpu_online(hctx->next_cpu));
1109 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
1111 blk_mq_sched_dispatch_requests(hctx);
1116 srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
1117 blk_mq_sched_dispatch_requests(hctx);
1118 srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
1123 * It'd be great if the workqueue API had a way to pass
1124 * in a mask and had some smarts for more clever placement.
1125 * For now we just round-robin here, switching for every
1126 * BLK_MQ_CPU_WORK_BATCH queued items.
1128 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
1130 if (hctx->queue->nr_hw_queues == 1)
1131 return WORK_CPU_UNBOUND;
1133 if (--hctx->next_cpu_batch <= 0) {
1136 next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
1137 if (next_cpu >= nr_cpu_ids)
1138 next_cpu = cpumask_first(hctx->cpumask);
1140 hctx->next_cpu = next_cpu;
1141 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
1144 return hctx->next_cpu;
1147 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
1148 unsigned long msecs)
1150 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx)))
1153 if (unlikely(blk_mq_hctx_stopped(hctx)))
1156 if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
1157 int cpu = get_cpu();
1158 if (cpumask_test_cpu(cpu, hctx->cpumask)) {
1159 __blk_mq_run_hw_queue(hctx);
1167 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1169 msecs_to_jiffies(msecs));
1172 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1174 __blk_mq_delay_run_hw_queue(hctx, true, msecs);
1176 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
1178 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1180 __blk_mq_delay_run_hw_queue(hctx, async, 0);
1182 EXPORT_SYMBOL(blk_mq_run_hw_queue);
1184 void blk_mq_run_hw_queues(struct request_queue *q, bool async)
1186 struct blk_mq_hw_ctx *hctx;
1189 queue_for_each_hw_ctx(q, hctx, i) {
1190 if (!blk_mq_hctx_has_pending(hctx) ||
1191 blk_mq_hctx_stopped(hctx))
1194 blk_mq_run_hw_queue(hctx, async);
1197 EXPORT_SYMBOL(blk_mq_run_hw_queues);
1200 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1201 * @q: request queue.
1203 * The caller is responsible for serializing this function against
1204 * blk_mq_{start,stop}_hw_queue().
1206 bool blk_mq_queue_stopped(struct request_queue *q)
1208 struct blk_mq_hw_ctx *hctx;
1211 queue_for_each_hw_ctx(q, hctx, i)
1212 if (blk_mq_hctx_stopped(hctx))
1217 EXPORT_SYMBOL(blk_mq_queue_stopped);
1220 * This function is often used for pausing .queue_rq() by driver when
1221 * there isn't enough resource or some conditions aren't satisfied, and
1222 * BLK_MQ_RQ_QUEUE_BUSY is usually returned.
1224 * We do not guarantee that dispatch can be drained or blocked
1225 * after blk_mq_stop_hw_queue() returns. Please use
1226 * blk_mq_quiesce_queue() for that requirement.
1228 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
1230 cancel_delayed_work(&hctx->run_work);
1232 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
1234 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
1237 * This function is often used for pausing .queue_rq() by driver when
1238 * there isn't enough resource or some conditions aren't satisfied, and
1239 * BLK_MQ_RQ_QUEUE_BUSY is usually returned.
1241 * We do not guarantee that dispatch can be drained or blocked
1242 * after blk_mq_stop_hw_queues() returns. Please use
1243 * blk_mq_quiesce_queue() for that requirement.
1245 void blk_mq_stop_hw_queues(struct request_queue *q)
1247 struct blk_mq_hw_ctx *hctx;
1250 queue_for_each_hw_ctx(q, hctx, i)
1251 blk_mq_stop_hw_queue(hctx);
1253 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
1255 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
1257 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1259 blk_mq_run_hw_queue(hctx, false);
1261 EXPORT_SYMBOL(blk_mq_start_hw_queue);
1263 void blk_mq_start_hw_queues(struct request_queue *q)
1265 struct blk_mq_hw_ctx *hctx;
1268 queue_for_each_hw_ctx(q, hctx, i)
1269 blk_mq_start_hw_queue(hctx);
1271 EXPORT_SYMBOL(blk_mq_start_hw_queues);
1273 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
1275 if (!blk_mq_hctx_stopped(hctx))
1278 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1279 blk_mq_run_hw_queue(hctx, async);
1281 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
1283 void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
1285 struct blk_mq_hw_ctx *hctx;
1288 queue_for_each_hw_ctx(q, hctx, i)
1289 blk_mq_start_stopped_hw_queue(hctx, async);
1291 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
1293 static void blk_mq_run_work_fn(struct work_struct *work)
1295 struct blk_mq_hw_ctx *hctx;
1297 hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work);
1300 * If we are stopped, don't run the queue. The exception is if
1301 * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear
1302 * the STOPPED bit and run it.
1304 if (test_bit(BLK_MQ_S_STOPPED, &hctx->state)) {
1305 if (!test_bit(BLK_MQ_S_START_ON_RUN, &hctx->state))
1308 clear_bit(BLK_MQ_S_START_ON_RUN, &hctx->state);
1309 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
1312 __blk_mq_run_hw_queue(hctx);
1316 void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
1318 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx)))
1322 * Stop the hw queue, then modify currently delayed work.
1323 * This should prevent us from running the queue prematurely.
1324 * Mark the queue as auto-clearing STOPPED when it runs.
1326 blk_mq_stop_hw_queue(hctx);
1327 set_bit(BLK_MQ_S_START_ON_RUN, &hctx->state);
1328 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
1330 msecs_to_jiffies(msecs));
1332 EXPORT_SYMBOL(blk_mq_delay_queue);
1334 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
1338 struct blk_mq_ctx *ctx = rq->mq_ctx;
1340 lockdep_assert_held(&ctx->lock);
1342 trace_block_rq_insert(hctx->queue, rq);
1345 list_add(&rq->queuelist, &ctx->rq_list);
1347 list_add_tail(&rq->queuelist, &ctx->rq_list);
1350 void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
1353 struct blk_mq_ctx *ctx = rq->mq_ctx;
1355 lockdep_assert_held(&ctx->lock);
1357 __blk_mq_insert_req_list(hctx, rq, at_head);
1358 blk_mq_hctx_mark_pending(hctx, ctx);
1361 void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
1362 struct list_head *list)
1366 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1369 spin_lock(&ctx->lock);
1370 while (!list_empty(list)) {
1373 rq = list_first_entry(list, struct request, queuelist);
1374 BUG_ON(rq->mq_ctx != ctx);
1375 list_del_init(&rq->queuelist);
1376 __blk_mq_insert_req_list(hctx, rq, false);
1378 blk_mq_hctx_mark_pending(hctx, ctx);
1379 spin_unlock(&ctx->lock);
1382 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
1384 struct request *rqa = container_of(a, struct request, queuelist);
1385 struct request *rqb = container_of(b, struct request, queuelist);
1387 return !(rqa->mq_ctx < rqb->mq_ctx ||
1388 (rqa->mq_ctx == rqb->mq_ctx &&
1389 blk_rq_pos(rqa) < blk_rq_pos(rqb)));
1392 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1394 struct blk_mq_ctx *this_ctx;
1395 struct request_queue *this_q;
1398 LIST_HEAD(ctx_list);
1401 list_splice_init(&plug->mq_list, &list);
1403 list_sort(NULL, &list, plug_ctx_cmp);
1409 while (!list_empty(&list)) {
1410 rq = list_entry_rq(list.next);
1411 list_del_init(&rq->queuelist);
1413 if (rq->mq_ctx != this_ctx) {
1415 trace_block_unplug(this_q, depth, from_schedule);
1416 blk_mq_sched_insert_requests(this_q, this_ctx,
1421 this_ctx = rq->mq_ctx;
1427 list_add_tail(&rq->queuelist, &ctx_list);
1431 * If 'this_ctx' is set, we know we have entries to complete
1432 * on 'ctx_list'. Do those.
1435 trace_block_unplug(this_q, depth, from_schedule);
1436 blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list,
1441 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
1443 blk_init_request_from_bio(rq, bio);
1445 blk_account_io_start(rq, true);
1448 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
1450 return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
1451 !blk_queue_nomerges(hctx->queue);
1454 static inline void blk_mq_queue_io(struct blk_mq_hw_ctx *hctx,
1455 struct blk_mq_ctx *ctx,
1458 spin_lock(&ctx->lock);
1459 __blk_mq_insert_request(hctx, rq, false);
1460 spin_unlock(&ctx->lock);
1463 static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
1466 return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false);
1468 return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
1471 static void __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1473 blk_qc_t *cookie, bool may_sleep)
1475 struct request_queue *q = rq->q;
1476 struct blk_mq_queue_data bd = {
1480 blk_qc_t new_cookie;
1482 bool run_queue = true;
1484 /* RCU or SRCU read lock is needed before checking quiesced flag */
1485 if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
1493 if (!blk_mq_get_driver_tag(rq, NULL, false))
1496 new_cookie = request_to_qc_t(hctx, rq);
1499 * For OK queue, we are done. For error, kill it. Any other
1500 * error (busy), just add it to our list as we previously
1503 ret = q->mq_ops->queue_rq(hctx, &bd);
1506 *cookie = new_cookie;
1508 case BLK_STS_RESOURCE:
1509 __blk_mq_requeue_request(rq);
1512 *cookie = BLK_QC_T_NONE;
1513 blk_mq_end_request(rq, ret);
1518 blk_mq_sched_insert_request(rq, false, run_queue, false, may_sleep);
1521 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
1522 struct request *rq, blk_qc_t *cookie)
1524 if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
1526 __blk_mq_try_issue_directly(hctx, rq, cookie, false);
1529 unsigned int srcu_idx;
1533 srcu_idx = srcu_read_lock(hctx->queue_rq_srcu);
1534 __blk_mq_try_issue_directly(hctx, rq, cookie, true);
1535 srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx);
1539 static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
1541 const int is_sync = op_is_sync(bio->bi_opf);
1542 const int is_flush_fua = op_is_flush(bio->bi_opf);
1543 struct blk_mq_alloc_data data = { .flags = 0 };
1545 unsigned int request_count = 0;
1546 struct blk_plug *plug;
1547 struct request *same_queue_rq = NULL;
1549 unsigned int wb_acct;
1551 blk_queue_bounce(q, &bio);
1553 blk_queue_split(q, &bio);
1555 if (!bio_integrity_prep(bio))
1556 return BLK_QC_T_NONE;
1558 if (!is_flush_fua && !blk_queue_nomerges(q) &&
1559 blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
1560 return BLK_QC_T_NONE;
1562 if (blk_mq_sched_bio_merge(q, bio))
1563 return BLK_QC_T_NONE;
1565 wb_acct = wbt_wait(q->rq_wb, bio, NULL);
1567 trace_block_getrq(q, bio, bio->bi_opf);
1569 rq = blk_mq_get_request(q, bio, bio->bi_opf, &data);
1570 if (unlikely(!rq)) {
1571 __wbt_done(q->rq_wb, wb_acct);
1572 if (bio->bi_opf & REQ_NOWAIT)
1573 bio_wouldblock_error(bio);
1574 return BLK_QC_T_NONE;
1577 wbt_track(&rq->issue_stat, wb_acct);
1579 cookie = request_to_qc_t(data.hctx, rq);
1581 plug = current->plug;
1582 if (unlikely(is_flush_fua)) {
1583 blk_mq_put_ctx(data.ctx);
1584 blk_mq_bio_to_request(rq, bio);
1586 blk_mq_sched_insert_request(rq, false, true, true,
1589 blk_insert_flush(rq);
1590 blk_mq_run_hw_queue(data.hctx, true);
1592 } else if (plug && q->nr_hw_queues == 1) {
1593 struct request *last = NULL;
1595 blk_mq_put_ctx(data.ctx);
1596 blk_mq_bio_to_request(rq, bio);
1599 * @request_count may become stale because of schedule
1600 * out, so check the list again.
1602 if (list_empty(&plug->mq_list))
1604 else if (blk_queue_nomerges(q))
1605 request_count = blk_plug_queued_count(q);
1608 trace_block_plug(q);
1610 last = list_entry_rq(plug->mq_list.prev);
1612 if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
1613 blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
1614 blk_flush_plug_list(plug, false);
1615 trace_block_plug(q);
1618 list_add_tail(&rq->queuelist, &plug->mq_list);
1619 } else if (plug && !blk_queue_nomerges(q)) {
1620 blk_mq_bio_to_request(rq, bio);
1623 * We do limited plugging. If the bio can be merged, do that.
1624 * Otherwise the existing request in the plug list will be
1625 * issued. So the plug list will have one request at most
1626 * The plug list might get flushed before this. If that happens,
1627 * the plug list is empty, and same_queue_rq is invalid.
1629 if (list_empty(&plug->mq_list))
1630 same_queue_rq = NULL;
1632 list_del_init(&same_queue_rq->queuelist);
1633 list_add_tail(&rq->queuelist, &plug->mq_list);
1635 blk_mq_put_ctx(data.ctx);
1637 if (same_queue_rq) {
1638 data.hctx = blk_mq_map_queue(q,
1639 same_queue_rq->mq_ctx->cpu);
1640 blk_mq_try_issue_directly(data.hctx, same_queue_rq,
1643 } else if (q->nr_hw_queues > 1 && is_sync) {
1644 blk_mq_put_ctx(data.ctx);
1645 blk_mq_bio_to_request(rq, bio);
1646 blk_mq_try_issue_directly(data.hctx, rq, &cookie);
1647 } else if (q->elevator) {
1648 blk_mq_put_ctx(data.ctx);
1649 blk_mq_bio_to_request(rq, bio);
1650 blk_mq_sched_insert_request(rq, false, true, true, true);
1652 blk_mq_put_ctx(data.ctx);
1653 blk_mq_bio_to_request(rq, bio);
1654 blk_mq_queue_io(data.hctx, data.ctx, rq);
1655 blk_mq_run_hw_queue(data.hctx, true);
1661 void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1662 unsigned int hctx_idx)
1666 if (tags->rqs && set->ops->exit_request) {
1669 for (i = 0; i < tags->nr_tags; i++) {
1670 struct request *rq = tags->static_rqs[i];
1674 set->ops->exit_request(set, rq, hctx_idx);
1675 tags->static_rqs[i] = NULL;
1679 while (!list_empty(&tags->page_list)) {
1680 page = list_first_entry(&tags->page_list, struct page, lru);
1681 list_del_init(&page->lru);
1683 * Remove kmemleak object previously allocated in
1684 * blk_mq_init_rq_map().
1686 kmemleak_free(page_address(page));
1687 __free_pages(page, page->private);
1691 void blk_mq_free_rq_map(struct blk_mq_tags *tags)
1695 kfree(tags->static_rqs);
1696 tags->static_rqs = NULL;
1698 blk_mq_free_tags(tags);
1701 struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
1702 unsigned int hctx_idx,
1703 unsigned int nr_tags,
1704 unsigned int reserved_tags)
1706 struct blk_mq_tags *tags;
1709 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1710 if (node == NUMA_NO_NODE)
1711 node = set->numa_node;
1713 tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
1714 BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
1718 tags->rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1719 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1722 blk_mq_free_tags(tags);
1726 tags->static_rqs = kzalloc_node(nr_tags * sizeof(struct request *),
1727 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
1729 if (!tags->static_rqs) {
1731 blk_mq_free_tags(tags);
1738 static size_t order_to_size(unsigned int order)
1740 return (size_t)PAGE_SIZE << order;
1743 int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
1744 unsigned int hctx_idx, unsigned int depth)
1746 unsigned int i, j, entries_per_page, max_order = 4;
1747 size_t rq_size, left;
1750 node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx);
1751 if (node == NUMA_NO_NODE)
1752 node = set->numa_node;
1754 INIT_LIST_HEAD(&tags->page_list);
1757 * rq_size is the size of the request plus driver payload, rounded
1758 * to the cacheline size
1760 rq_size = round_up(sizeof(struct request) + set->cmd_size,
1762 left = rq_size * depth;
1764 for (i = 0; i < depth; ) {
1765 int this_order = max_order;
1770 while (this_order && left < order_to_size(this_order - 1))
1774 page = alloc_pages_node(node,
1775 GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
1781 if (order_to_size(this_order) < rq_size)
1788 page->private = this_order;
1789 list_add_tail(&page->lru, &tags->page_list);
1791 p = page_address(page);
1793 * Allow kmemleak to scan these pages as they contain pointers
1794 * to additional allocations like via ops->init_request().
1796 kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
1797 entries_per_page = order_to_size(this_order) / rq_size;
1798 to_do = min(entries_per_page, depth - i);
1799 left -= to_do * rq_size;
1800 for (j = 0; j < to_do; j++) {
1801 struct request *rq = p;
1803 tags->static_rqs[i] = rq;
1804 if (set->ops->init_request) {
1805 if (set->ops->init_request(set, rq, hctx_idx,
1807 tags->static_rqs[i] = NULL;
1819 blk_mq_free_rqs(set, tags, hctx_idx);
1824 * 'cpu' is going away. splice any existing rq_list entries from this
1825 * software queue to the hw queue dispatch list, and ensure that it
1828 static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
1830 struct blk_mq_hw_ctx *hctx;
1831 struct blk_mq_ctx *ctx;
1834 hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
1835 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
1837 spin_lock(&ctx->lock);
1838 if (!list_empty(&ctx->rq_list)) {
1839 list_splice_init(&ctx->rq_list, &tmp);
1840 blk_mq_hctx_clear_pending(hctx, ctx);
1842 spin_unlock(&ctx->lock);
1844 if (list_empty(&tmp))
1847 spin_lock(&hctx->lock);
1848 list_splice_tail_init(&tmp, &hctx->dispatch);
1849 spin_unlock(&hctx->lock);
1851 blk_mq_run_hw_queue(hctx, true);
1855 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
1857 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
1861 /* hctx->ctxs will be freed in queue's release handler */
1862 static void blk_mq_exit_hctx(struct request_queue *q,
1863 struct blk_mq_tag_set *set,
1864 struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
1866 blk_mq_debugfs_unregister_hctx(hctx);
1868 blk_mq_tag_idle(hctx);
1870 if (set->ops->exit_request)
1871 set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
1873 blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
1875 if (set->ops->exit_hctx)
1876 set->ops->exit_hctx(hctx, hctx_idx);
1878 if (hctx->flags & BLK_MQ_F_BLOCKING)
1879 cleanup_srcu_struct(hctx->queue_rq_srcu);
1881 blk_mq_remove_cpuhp(hctx);
1882 blk_free_flush_queue(hctx->fq);
1883 sbitmap_free(&hctx->ctx_map);
1886 static void blk_mq_exit_hw_queues(struct request_queue *q,
1887 struct blk_mq_tag_set *set, int nr_queue)
1889 struct blk_mq_hw_ctx *hctx;
1892 queue_for_each_hw_ctx(q, hctx, i) {
1895 blk_mq_exit_hctx(q, set, hctx, i);
1899 static int blk_mq_init_hctx(struct request_queue *q,
1900 struct blk_mq_tag_set *set,
1901 struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
1905 node = hctx->numa_node;
1906 if (node == NUMA_NO_NODE)
1907 node = hctx->numa_node = set->numa_node;
1909 INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
1910 spin_lock_init(&hctx->lock);
1911 INIT_LIST_HEAD(&hctx->dispatch);
1913 hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
1915 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
1917 hctx->tags = set->tags[hctx_idx];
1920 * Allocate space for all possible cpus to avoid allocation at
1923 hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1926 goto unregister_cpu_notifier;
1928 if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
1934 if (set->ops->init_hctx &&
1935 set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
1938 if (blk_mq_sched_init_hctx(q, hctx, hctx_idx))
1941 hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
1943 goto sched_exit_hctx;
1945 if (set->ops->init_request &&
1946 set->ops->init_request(set, hctx->fq->flush_rq, hctx_idx,
1950 if (hctx->flags & BLK_MQ_F_BLOCKING)
1951 init_srcu_struct(hctx->queue_rq_srcu);
1953 blk_mq_debugfs_register_hctx(q, hctx);
1960 blk_mq_sched_exit_hctx(q, hctx, hctx_idx);
1962 if (set->ops->exit_hctx)
1963 set->ops->exit_hctx(hctx, hctx_idx);
1965 sbitmap_free(&hctx->ctx_map);
1968 unregister_cpu_notifier:
1969 blk_mq_remove_cpuhp(hctx);
1973 static void blk_mq_init_cpu_queues(struct request_queue *q,
1974 unsigned int nr_hw_queues)
1978 for_each_possible_cpu(i) {
1979 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1980 struct blk_mq_hw_ctx *hctx;
1983 spin_lock_init(&__ctx->lock);
1984 INIT_LIST_HEAD(&__ctx->rq_list);
1987 /* If the cpu isn't present, the cpu is mapped to first hctx */
1988 if (!cpu_present(i))
1991 hctx = blk_mq_map_queue(q, i);
1994 * Set local node, IFF we have more than one hw queue. If
1995 * not, we remain on the home node of the device
1997 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
1998 hctx->numa_node = local_memory_node(cpu_to_node(i));
2002 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
2006 set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
2007 set->queue_depth, set->reserved_tags);
2008 if (!set->tags[hctx_idx])
2011 ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
2016 blk_mq_free_rq_map(set->tags[hctx_idx]);
2017 set->tags[hctx_idx] = NULL;
2021 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
2022 unsigned int hctx_idx)
2024 if (set->tags[hctx_idx]) {
2025 blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
2026 blk_mq_free_rq_map(set->tags[hctx_idx]);
2027 set->tags[hctx_idx] = NULL;
2031 static void blk_mq_map_swqueue(struct request_queue *q)
2033 unsigned int i, hctx_idx;
2034 struct blk_mq_hw_ctx *hctx;
2035 struct blk_mq_ctx *ctx;
2036 struct blk_mq_tag_set *set = q->tag_set;
2039 * Avoid others reading imcomplete hctx->cpumask through sysfs
2041 mutex_lock(&q->sysfs_lock);
2043 queue_for_each_hw_ctx(q, hctx, i) {
2044 cpumask_clear(hctx->cpumask);
2049 * Map software to hardware queues.
2051 * If the cpu isn't present, the cpu is mapped to first hctx.
2053 for_each_present_cpu(i) {
2054 hctx_idx = q->mq_map[i];
2055 /* unmapped hw queue can be remapped after CPU topo changed */
2056 if (!set->tags[hctx_idx] &&
2057 !__blk_mq_alloc_rq_map(set, hctx_idx)) {
2059 * If tags initialization fail for some hctx,
2060 * that hctx won't be brought online. In this
2061 * case, remap the current ctx to hctx[0] which
2062 * is guaranteed to always have tags allocated
2067 ctx = per_cpu_ptr(q->queue_ctx, i);
2068 hctx = blk_mq_map_queue(q, i);
2070 cpumask_set_cpu(i, hctx->cpumask);
2071 ctx->index_hw = hctx->nr_ctx;
2072 hctx->ctxs[hctx->nr_ctx++] = ctx;
2075 mutex_unlock(&q->sysfs_lock);
2077 queue_for_each_hw_ctx(q, hctx, i) {
2079 * If no software queues are mapped to this hardware queue,
2080 * disable it and free the request entries.
2082 if (!hctx->nr_ctx) {
2083 /* Never unmap queue 0. We need it as a
2084 * fallback in case of a new remap fails
2087 if (i && set->tags[i])
2088 blk_mq_free_map_and_requests(set, i);
2094 hctx->tags = set->tags[i];
2095 WARN_ON(!hctx->tags);
2098 * Set the map size to the number of mapped software queues.
2099 * This is more accurate and more efficient than looping
2100 * over all possibly mapped software queues.
2102 sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
2105 * Initialize batch roundrobin counts
2107 hctx->next_cpu = cpumask_first(hctx->cpumask);
2108 hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
2113 * Caller needs to ensure that we're either frozen/quiesced, or that
2114 * the queue isn't live yet.
2116 static void queue_set_hctx_shared(struct request_queue *q, bool shared)
2118 struct blk_mq_hw_ctx *hctx;
2121 queue_for_each_hw_ctx(q, hctx, i) {
2123 if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
2124 atomic_inc(&q->shared_hctx_restart);
2125 hctx->flags |= BLK_MQ_F_TAG_SHARED;
2127 if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
2128 atomic_dec(&q->shared_hctx_restart);
2129 hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
2134 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set,
2137 struct request_queue *q;
2139 lockdep_assert_held(&set->tag_list_lock);
2141 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2142 blk_mq_freeze_queue(q);
2143 queue_set_hctx_shared(q, shared);
2144 blk_mq_unfreeze_queue(q);
2148 static void blk_mq_del_queue_tag_set(struct request_queue *q)
2150 struct blk_mq_tag_set *set = q->tag_set;
2152 mutex_lock(&set->tag_list_lock);
2153 list_del_rcu(&q->tag_set_list);
2154 INIT_LIST_HEAD(&q->tag_set_list);
2155 if (list_is_singular(&set->tag_list)) {
2156 /* just transitioned to unshared */
2157 set->flags &= ~BLK_MQ_F_TAG_SHARED;
2158 /* update existing queue */
2159 blk_mq_update_tag_set_depth(set, false);
2161 mutex_unlock(&set->tag_list_lock);
2166 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
2167 struct request_queue *q)
2171 mutex_lock(&set->tag_list_lock);
2173 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2174 if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
2175 set->flags |= BLK_MQ_F_TAG_SHARED;
2176 /* update existing queue */
2177 blk_mq_update_tag_set_depth(set, true);
2179 if (set->flags & BLK_MQ_F_TAG_SHARED)
2180 queue_set_hctx_shared(q, true);
2181 list_add_tail_rcu(&q->tag_set_list, &set->tag_list);
2183 mutex_unlock(&set->tag_list_lock);
2187 * It is the actual release handler for mq, but we do it from
2188 * request queue's release handler for avoiding use-after-free
2189 * and headache because q->mq_kobj shouldn't have been introduced,
2190 * but we can't group ctx/kctx kobj without it.
2192 void blk_mq_release(struct request_queue *q)
2194 struct blk_mq_hw_ctx *hctx;
2197 /* hctx kobj stays in hctx */
2198 queue_for_each_hw_ctx(q, hctx, i) {
2201 kobject_put(&hctx->kobj);
2206 kfree(q->queue_hw_ctx);
2209 * release .mq_kobj and sw queue's kobject now because
2210 * both share lifetime with request queue.
2212 blk_mq_sysfs_deinit(q);
2214 free_percpu(q->queue_ctx);
2217 struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
2219 struct request_queue *uninit_q, *q;
2221 uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
2223 return ERR_PTR(-ENOMEM);
2225 q = blk_mq_init_allocated_queue(set, uninit_q);
2227 blk_cleanup_queue(uninit_q);
2231 EXPORT_SYMBOL(blk_mq_init_queue);
2233 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
2235 int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
2237 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, queue_rq_srcu),
2238 __alignof__(struct blk_mq_hw_ctx)) !=
2239 sizeof(struct blk_mq_hw_ctx));
2241 if (tag_set->flags & BLK_MQ_F_BLOCKING)
2242 hw_ctx_size += sizeof(struct srcu_struct);
2247 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
2248 struct request_queue *q)
2251 struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
2253 blk_mq_sysfs_unregister(q);
2254 for (i = 0; i < set->nr_hw_queues; i++) {
2260 node = blk_mq_hw_queue_to_node(q->mq_map, i);
2261 hctxs[i] = kzalloc_node(blk_mq_hw_ctx_size(set),
2266 if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
2273 atomic_set(&hctxs[i]->nr_active, 0);
2274 hctxs[i]->numa_node = node;
2275 hctxs[i]->queue_num = i;
2277 if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
2278 free_cpumask_var(hctxs[i]->cpumask);
2283 blk_mq_hctx_kobj_init(hctxs[i]);
2285 for (j = i; j < q->nr_hw_queues; j++) {
2286 struct blk_mq_hw_ctx *hctx = hctxs[j];
2290 blk_mq_free_map_and_requests(set, j);
2291 blk_mq_exit_hctx(q, set, hctx, j);
2292 kobject_put(&hctx->kobj);
2297 q->nr_hw_queues = i;
2298 blk_mq_sysfs_register(q);
2301 struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
2302 struct request_queue *q)
2304 /* mark the queue as mq asap */
2305 q->mq_ops = set->ops;
2307 q->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
2308 blk_mq_poll_stats_bkt,
2309 BLK_MQ_POLL_STATS_BKTS, q);
2313 q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
2317 /* init q->mq_kobj and sw queues' kobjects */
2318 blk_mq_sysfs_init(q);
2320 q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
2321 GFP_KERNEL, set->numa_node);
2322 if (!q->queue_hw_ctx)
2325 q->mq_map = set->mq_map;
2327 blk_mq_realloc_hw_ctxs(set, q);
2328 if (!q->nr_hw_queues)
2331 INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
2332 blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
2334 q->nr_queues = nr_cpu_ids;
2336 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
2338 if (!(set->flags & BLK_MQ_F_SG_MERGE))
2339 q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
2341 q->sg_reserved_size = INT_MAX;
2343 INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
2344 INIT_LIST_HEAD(&q->requeue_list);
2345 spin_lock_init(&q->requeue_lock);
2347 blk_queue_make_request(q, blk_mq_make_request);
2350 * Do this after blk_queue_make_request() overrides it...
2352 q->nr_requests = set->queue_depth;
2355 * Default to classic polling
2359 if (set->ops->complete)
2360 blk_queue_softirq_done(q, set->ops->complete);
2362 blk_mq_init_cpu_queues(q, set->nr_hw_queues);
2363 blk_mq_add_queue_tag_set(set, q);
2364 blk_mq_map_swqueue(q);
2366 if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
2369 ret = blk_mq_sched_init(q);
2371 return ERR_PTR(ret);
2377 kfree(q->queue_hw_ctx);
2379 free_percpu(q->queue_ctx);
2382 return ERR_PTR(-ENOMEM);
2384 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
2386 void blk_mq_free_queue(struct request_queue *q)
2388 struct blk_mq_tag_set *set = q->tag_set;
2390 blk_mq_del_queue_tag_set(q);
2391 blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
2394 /* Basically redo blk_mq_init_queue with queue frozen */
2395 static void blk_mq_queue_reinit(struct request_queue *q)
2397 WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
2399 blk_mq_debugfs_unregister_hctxs(q);
2400 blk_mq_sysfs_unregister(q);
2403 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2404 * we should change hctx numa_node according to new topology (this
2405 * involves free and re-allocate memory, worthy doing?)
2408 blk_mq_map_swqueue(q);
2410 blk_mq_sysfs_register(q);
2411 blk_mq_debugfs_register_hctxs(q);
2414 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2418 for (i = 0; i < set->nr_hw_queues; i++)
2419 if (!__blk_mq_alloc_rq_map(set, i))
2426 blk_mq_free_rq_map(set->tags[i]);
2432 * Allocate the request maps associated with this tag_set. Note that this
2433 * may reduce the depth asked for, if memory is tight. set->queue_depth
2434 * will be updated to reflect the allocated depth.
2436 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
2441 depth = set->queue_depth;
2443 err = __blk_mq_alloc_rq_maps(set);
2447 set->queue_depth >>= 1;
2448 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
2452 } while (set->queue_depth);
2454 if (!set->queue_depth || err) {
2455 pr_err("blk-mq: failed to allocate request map\n");
2459 if (depth != set->queue_depth)
2460 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2461 depth, set->queue_depth);
2466 static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
2468 if (set->ops->map_queues)
2469 return set->ops->map_queues(set);
2471 return blk_mq_map_queues(set);
2475 * Alloc a tag set to be associated with one or more request queues.
2476 * May fail with EINVAL for various error conditions. May adjust the
2477 * requested depth down, if if it too large. In that case, the set
2478 * value will be stored in set->queue_depth.
2480 int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
2484 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
2486 if (!set->nr_hw_queues)
2488 if (!set->queue_depth)
2490 if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
2493 if (!set->ops->queue_rq)
2496 if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
2497 pr_info("blk-mq: reduced tag depth to %u\n",
2499 set->queue_depth = BLK_MQ_MAX_DEPTH;
2503 * If a crashdump is active, then we are potentially in a very
2504 * memory constrained environment. Limit us to 1 queue and
2505 * 64 tags to prevent using too much memory.
2507 if (is_kdump_kernel()) {
2508 set->nr_hw_queues = 1;
2509 set->queue_depth = min(64U, set->queue_depth);
2512 * There is no use for more h/w queues than cpus.
2514 if (set->nr_hw_queues > nr_cpu_ids)
2515 set->nr_hw_queues = nr_cpu_ids;
2517 set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
2518 GFP_KERNEL, set->numa_node);
2523 set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
2524 GFP_KERNEL, set->numa_node);
2528 ret = blk_mq_update_queue_map(set);
2530 goto out_free_mq_map;
2532 ret = blk_mq_alloc_rq_maps(set);
2534 goto out_free_mq_map;
2536 mutex_init(&set->tag_list_lock);
2537 INIT_LIST_HEAD(&set->tag_list);
2549 EXPORT_SYMBOL(blk_mq_alloc_tag_set);
2551 void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
2555 for (i = 0; i < nr_cpu_ids; i++)
2556 blk_mq_free_map_and_requests(set, i);
2564 EXPORT_SYMBOL(blk_mq_free_tag_set);
2566 int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
2568 struct blk_mq_tag_set *set = q->tag_set;
2569 struct blk_mq_hw_ctx *hctx;
2575 blk_mq_freeze_queue(q);
2578 queue_for_each_hw_ctx(q, hctx, i) {
2582 * If we're using an MQ scheduler, just update the scheduler
2583 * queue depth. This is similar to what the old code would do.
2585 if (!hctx->sched_tags) {
2586 ret = blk_mq_tag_update_depth(hctx, &hctx->tags,
2587 min(nr, set->queue_depth),
2590 ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
2598 q->nr_requests = nr;
2600 blk_mq_unfreeze_queue(q);
2605 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
2608 struct request_queue *q;
2610 lockdep_assert_held(&set->tag_list_lock);
2612 if (nr_hw_queues > nr_cpu_ids)
2613 nr_hw_queues = nr_cpu_ids;
2614 if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
2617 list_for_each_entry(q, &set->tag_list, tag_set_list)
2618 blk_mq_freeze_queue(q);
2620 set->nr_hw_queues = nr_hw_queues;
2621 blk_mq_update_queue_map(set);
2622 list_for_each_entry(q, &set->tag_list, tag_set_list) {
2623 blk_mq_realloc_hw_ctxs(set, q);
2624 blk_mq_queue_reinit(q);
2627 list_for_each_entry(q, &set->tag_list, tag_set_list)
2628 blk_mq_unfreeze_queue(q);
2631 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
2633 mutex_lock(&set->tag_list_lock);
2634 __blk_mq_update_nr_hw_queues(set, nr_hw_queues);
2635 mutex_unlock(&set->tag_list_lock);
2637 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
2639 /* Enable polling stats and return whether they were already enabled. */
2640 static bool blk_poll_stats_enable(struct request_queue *q)
2642 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
2643 test_and_set_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
2645 blk_stat_add_callback(q, q->poll_cb);
2649 static void blk_mq_poll_stats_start(struct request_queue *q)
2652 * We don't arm the callback if polling stats are not enabled or the
2653 * callback is already active.
2655 if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
2656 blk_stat_is_active(q->poll_cb))
2659 blk_stat_activate_msecs(q->poll_cb, 100);
2662 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
2664 struct request_queue *q = cb->data;
2667 for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
2668 if (cb->stat[bucket].nr_samples)
2669 q->poll_stat[bucket] = cb->stat[bucket];
2673 static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
2674 struct blk_mq_hw_ctx *hctx,
2677 unsigned long ret = 0;
2681 * If stats collection isn't on, don't sleep but turn it on for
2684 if (!blk_poll_stats_enable(q))
2688 * As an optimistic guess, use half of the mean service time
2689 * for this type of request. We can (and should) make this smarter.
2690 * For instance, if the completion latencies are tight, we can
2691 * get closer than just half the mean. This is especially
2692 * important on devices where the completion latencies are longer
2693 * than ~10 usec. We do use the stats for the relevant IO size
2694 * if available which does lead to better estimates.
2696 bucket = blk_mq_poll_stats_bkt(rq);
2700 if (q->poll_stat[bucket].nr_samples)
2701 ret = (q->poll_stat[bucket].mean + 1) / 2;
2706 static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
2707 struct blk_mq_hw_ctx *hctx,
2710 struct hrtimer_sleeper hs;
2711 enum hrtimer_mode mode;
2715 if (test_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags))
2721 * -1: don't ever hybrid sleep
2722 * 0: use half of prev avg
2723 * >0: use this specific value
2725 if (q->poll_nsec == -1)
2727 else if (q->poll_nsec > 0)
2728 nsecs = q->poll_nsec;
2730 nsecs = blk_mq_poll_nsecs(q, hctx, rq);
2735 set_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
2738 * This will be replaced with the stats tracking code, using
2739 * 'avg_completion_time / 2' as the pre-sleep target.
2743 mode = HRTIMER_MODE_REL;
2744 hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
2745 hrtimer_set_expires(&hs.timer, kt);
2747 hrtimer_init_sleeper(&hs, current);
2749 if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
2751 set_current_state(TASK_UNINTERRUPTIBLE);
2752 hrtimer_start_expires(&hs.timer, mode);
2755 hrtimer_cancel(&hs.timer);
2756 mode = HRTIMER_MODE_ABS;
2757 } while (hs.task && !signal_pending(current));
2759 __set_current_state(TASK_RUNNING);
2760 destroy_hrtimer_on_stack(&hs.timer);
2764 static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
2766 struct request_queue *q = hctx->queue;
2770 * If we sleep, have the caller restart the poll loop to reset
2771 * the state. Like for the other success return cases, the
2772 * caller is responsible for checking if the IO completed. If
2773 * the IO isn't complete, we'll get called again and will go
2774 * straight to the busy poll loop.
2776 if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
2779 hctx->poll_considered++;
2781 state = current->state;
2782 while (!need_resched()) {
2785 hctx->poll_invoked++;
2787 ret = q->mq_ops->poll(hctx, rq->tag);
2789 hctx->poll_success++;
2790 set_current_state(TASK_RUNNING);
2794 if (signal_pending_state(state, current))
2795 set_current_state(TASK_RUNNING);
2797 if (current->state == TASK_RUNNING)
2807 bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
2809 struct blk_mq_hw_ctx *hctx;
2810 struct blk_plug *plug;
2813 if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) ||
2814 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
2817 plug = current->plug;
2819 blk_flush_plug_list(plug, false);
2821 hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
2822 if (!blk_qc_t_is_internal(cookie))
2823 rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
2825 rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
2827 * With scheduling, if the request has completed, we'll
2828 * get a NULL return here, as we clear the sched tag when
2829 * that happens. The request still remains valid, like always,
2830 * so we should be safe with just the NULL check.
2836 return __blk_mq_poll(hctx, rq);
2838 EXPORT_SYMBOL_GPL(blk_mq_poll);
2840 static int __init blk_mq_init(void)
2842 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
2843 blk_mq_hctx_notify_dead);
2846 subsys_initcall(blk_mq_init);