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-tag.h"
37 #include "blk-mq-sched.h"
39 static DEFINE_MUTEX(all_q_mutex
);
40 static LIST_HEAD(all_q_list
);
42 static void blk_mq_poll_stats_start(struct request_queue
*q
);
43 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
);
46 * Check if any of the ctx's have pending work in this hardware queue
48 bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
50 return sbitmap_any_bit_set(&hctx
->ctx_map
) ||
51 !list_empty_careful(&hctx
->dispatch
) ||
52 blk_mq_sched_has_work(hctx
);
56 * Mark this ctx as having pending work in this hardware queue
58 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
59 struct blk_mq_ctx
*ctx
)
61 if (!sbitmap_test_bit(&hctx
->ctx_map
, ctx
->index_hw
))
62 sbitmap_set_bit(&hctx
->ctx_map
, ctx
->index_hw
);
65 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
66 struct blk_mq_ctx
*ctx
)
68 sbitmap_clear_bit(&hctx
->ctx_map
, ctx
->index_hw
);
71 void blk_mq_freeze_queue_start(struct request_queue
*q
)
75 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
76 if (freeze_depth
== 1) {
77 percpu_ref_kill(&q
->q_usage_counter
);
78 blk_mq_run_hw_queues(q
, false);
81 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start
);
83 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
85 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
87 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
89 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
90 unsigned long timeout
)
92 return wait_event_timeout(q
->mq_freeze_wq
,
93 percpu_ref_is_zero(&q
->q_usage_counter
),
96 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
99 * Guarantee no request is in use, so we can change any data structure of
100 * the queue afterward.
102 void blk_freeze_queue(struct request_queue
*q
)
105 * In the !blk_mq case we are only calling this to kill the
106 * q_usage_counter, otherwise this increases the freeze depth
107 * and waits for it to return to zero. For this reason there is
108 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
109 * exported to drivers as the only user for unfreeze is blk_mq.
111 blk_mq_freeze_queue_start(q
);
112 blk_mq_freeze_queue_wait(q
);
115 void blk_mq_freeze_queue(struct request_queue
*q
)
118 * ...just an alias to keep freeze and unfreeze actions balanced
119 * in the blk_mq_* namespace
123 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
125 void blk_mq_unfreeze_queue(struct request_queue
*q
)
129 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
130 WARN_ON_ONCE(freeze_depth
< 0);
132 percpu_ref_reinit(&q
->q_usage_counter
);
133 wake_up_all(&q
->mq_freeze_wq
);
136 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
139 * blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished
142 * Note: this function does not prevent that the struct request end_io()
143 * callback function is invoked. Additionally, it is not prevented that
144 * new queue_rq() calls occur unless the queue has been stopped first.
146 void blk_mq_quiesce_queue(struct request_queue
*q
)
148 struct blk_mq_hw_ctx
*hctx
;
152 blk_mq_stop_hw_queues(q
);
154 queue_for_each_hw_ctx(q
, hctx
, i
) {
155 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
156 synchronize_srcu(&hctx
->queue_rq_srcu
);
163 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
165 void blk_mq_wake_waiters(struct request_queue
*q
)
167 struct blk_mq_hw_ctx
*hctx
;
170 queue_for_each_hw_ctx(q
, hctx
, i
)
171 if (blk_mq_hw_queue_mapped(hctx
))
172 blk_mq_tag_wakeup_all(hctx
->tags
, true);
175 * If we are called because the queue has now been marked as
176 * dying, we need to ensure that processes currently waiting on
177 * the queue are notified as well.
179 wake_up_all(&q
->mq_freeze_wq
);
182 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
184 return blk_mq_has_free_tags(hctx
->tags
);
186 EXPORT_SYMBOL(blk_mq_can_queue
);
188 void blk_mq_rq_ctx_init(struct request_queue
*q
, struct blk_mq_ctx
*ctx
,
189 struct request
*rq
, unsigned int op
)
191 INIT_LIST_HEAD(&rq
->queuelist
);
192 /* csd/requeue_work/fifo_time is initialized before use */
196 if (blk_queue_io_stat(q
))
197 rq
->rq_flags
|= RQF_IO_STAT
;
198 /* do not touch atomic flags, it needs atomic ops against the timer */
200 INIT_HLIST_NODE(&rq
->hash
);
201 RB_CLEAR_NODE(&rq
->rb_node
);
204 rq
->start_time
= jiffies
;
205 #ifdef CONFIG_BLK_CGROUP
207 set_start_time_ns(rq
);
208 rq
->io_start_time_ns
= 0;
210 rq
->nr_phys_segments
= 0;
211 #if defined(CONFIG_BLK_DEV_INTEGRITY)
212 rq
->nr_integrity_segments
= 0;
215 /* tag was already set */
219 INIT_LIST_HEAD(&rq
->timeout_list
);
223 rq
->end_io_data
= NULL
;
226 ctx
->rq_dispatched
[op_is_sync(op
)]++;
228 EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init
);
230 struct request
*__blk_mq_alloc_request(struct blk_mq_alloc_data
*data
,
236 tag
= blk_mq_get_tag(data
);
237 if (tag
!= BLK_MQ_TAG_FAIL
) {
238 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
240 rq
= tags
->static_rqs
[tag
];
242 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
244 rq
->internal_tag
= tag
;
246 if (blk_mq_tag_busy(data
->hctx
)) {
247 rq
->rq_flags
= RQF_MQ_INFLIGHT
;
248 atomic_inc(&data
->hctx
->nr_active
);
251 rq
->internal_tag
= -1;
252 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
255 blk_mq_rq_ctx_init(data
->q
, data
->ctx
, rq
, op
);
261 EXPORT_SYMBOL_GPL(__blk_mq_alloc_request
);
263 struct request
*blk_mq_alloc_request(struct request_queue
*q
, int rw
,
266 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
270 ret
= blk_queue_enter(q
, flags
& BLK_MQ_REQ_NOWAIT
);
274 rq
= blk_mq_sched_get_request(q
, NULL
, rw
, &alloc_data
);
276 blk_mq_put_ctx(alloc_data
.ctx
);
280 return ERR_PTR(-EWOULDBLOCK
);
283 rq
->__sector
= (sector_t
) -1;
284 rq
->bio
= rq
->biotail
= NULL
;
287 EXPORT_SYMBOL(blk_mq_alloc_request
);
289 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
, int rw
,
290 unsigned int flags
, unsigned int hctx_idx
)
292 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
298 * If the tag allocator sleeps we could get an allocation for a
299 * different hardware context. No need to complicate the low level
300 * allocator for this for the rare use case of a command tied to
303 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
304 return ERR_PTR(-EINVAL
);
306 if (hctx_idx
>= q
->nr_hw_queues
)
307 return ERR_PTR(-EIO
);
309 ret
= blk_queue_enter(q
, true);
314 * Check if the hardware context is actually mapped to anything.
315 * If not tell the caller that it should skip this queue.
317 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
318 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
320 return ERR_PTR(-EXDEV
);
322 cpu
= cpumask_first(alloc_data
.hctx
->cpumask
);
323 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
325 rq
= blk_mq_sched_get_request(q
, NULL
, rw
, &alloc_data
);
327 blk_mq_put_ctx(alloc_data
.ctx
);
331 return ERR_PTR(-EWOULDBLOCK
);
335 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
337 void __blk_mq_finish_request(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
340 const int sched_tag
= rq
->internal_tag
;
341 struct request_queue
*q
= rq
->q
;
343 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
344 atomic_dec(&hctx
->nr_active
);
346 wbt_done(q
->rq_wb
, &rq
->issue_stat
);
349 clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
350 clear_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
352 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
354 blk_mq_sched_completed_request(hctx
, rq
);
355 blk_mq_sched_restart_queues(hctx
);
359 static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx
*hctx
,
362 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
364 ctx
->rq_completed
[rq_is_sync(rq
)]++;
365 __blk_mq_finish_request(hctx
, ctx
, rq
);
368 void blk_mq_finish_request(struct request
*rq
)
370 blk_mq_finish_hctx_request(blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
), rq
);
373 void blk_mq_free_request(struct request
*rq
)
375 blk_mq_sched_put_request(rq
);
377 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
379 inline void __blk_mq_end_request(struct request
*rq
, int error
)
381 blk_account_io_done(rq
);
384 wbt_done(rq
->q
->rq_wb
, &rq
->issue_stat
);
385 rq
->end_io(rq
, error
);
387 if (unlikely(blk_bidi_rq(rq
)))
388 blk_mq_free_request(rq
->next_rq
);
389 blk_mq_free_request(rq
);
392 EXPORT_SYMBOL(__blk_mq_end_request
);
394 void blk_mq_end_request(struct request
*rq
, int error
)
396 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
398 __blk_mq_end_request(rq
, error
);
400 EXPORT_SYMBOL(blk_mq_end_request
);
402 static void __blk_mq_complete_request_remote(void *data
)
404 struct request
*rq
= data
;
406 rq
->q
->softirq_done_fn(rq
);
409 static void blk_mq_ipi_complete_request(struct request
*rq
)
411 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
415 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
416 rq
->q
->softirq_done_fn(rq
);
421 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
422 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
424 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
425 rq
->csd
.func
= __blk_mq_complete_request_remote
;
428 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
430 rq
->q
->softirq_done_fn(rq
);
435 static void blk_mq_stat_add(struct request
*rq
)
437 if (rq
->rq_flags
& RQF_STATS
) {
438 blk_mq_poll_stats_start(rq
->q
);
443 static void __blk_mq_complete_request(struct request
*rq
)
445 struct request_queue
*q
= rq
->q
;
449 if (!q
->softirq_done_fn
)
450 blk_mq_end_request(rq
, rq
->errors
);
452 blk_mq_ipi_complete_request(rq
);
456 * blk_mq_complete_request - end I/O on a request
457 * @rq: the request being processed
460 * Ends all I/O on a request. It does not handle partial completions.
461 * The actual completion happens out-of-order, through a IPI handler.
463 void blk_mq_complete_request(struct request
*rq
, int error
)
465 struct request_queue
*q
= rq
->q
;
467 if (unlikely(blk_should_fake_timeout(q
)))
469 if (!blk_mark_rq_complete(rq
)) {
471 __blk_mq_complete_request(rq
);
474 EXPORT_SYMBOL(blk_mq_complete_request
);
476 int blk_mq_request_started(struct request
*rq
)
478 return test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
480 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
482 void blk_mq_start_request(struct request
*rq
)
484 struct request_queue
*q
= rq
->q
;
486 blk_mq_sched_started_request(rq
);
488 trace_block_rq_issue(q
, rq
);
490 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
491 blk_stat_set_issue_time(&rq
->issue_stat
);
492 rq
->rq_flags
|= RQF_STATS
;
493 wbt_issue(q
->rq_wb
, &rq
->issue_stat
);
499 * Ensure that ->deadline is visible before set the started
500 * flag and clear the completed flag.
502 smp_mb__before_atomic();
505 * Mark us as started and clear complete. Complete might have been
506 * set if requeue raced with timeout, which then marked it as
507 * complete. So be sure to clear complete again when we start
508 * the request, otherwise we'll ignore the completion event.
510 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
))
511 set_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
);
512 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
513 clear_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
);
515 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
517 * Make sure space for the drain appears. We know we can do
518 * this because max_hw_segments has been adjusted to be one
519 * fewer than the device can handle.
521 rq
->nr_phys_segments
++;
524 EXPORT_SYMBOL(blk_mq_start_request
);
526 static void __blk_mq_requeue_request(struct request
*rq
)
528 struct request_queue
*q
= rq
->q
;
530 trace_block_rq_requeue(q
, rq
);
531 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
532 blk_mq_sched_requeue_request(rq
);
534 if (test_and_clear_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
535 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
536 rq
->nr_phys_segments
--;
540 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
542 __blk_mq_requeue_request(rq
);
544 BUG_ON(blk_queued_rq(rq
));
545 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
547 EXPORT_SYMBOL(blk_mq_requeue_request
);
549 static void blk_mq_requeue_work(struct work_struct
*work
)
551 struct request_queue
*q
=
552 container_of(work
, struct request_queue
, requeue_work
.work
);
554 struct request
*rq
, *next
;
557 spin_lock_irqsave(&q
->requeue_lock
, flags
);
558 list_splice_init(&q
->requeue_list
, &rq_list
);
559 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
561 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
562 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
565 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
566 list_del_init(&rq
->queuelist
);
567 blk_mq_sched_insert_request(rq
, true, false, false, true);
570 while (!list_empty(&rq_list
)) {
571 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
572 list_del_init(&rq
->queuelist
);
573 blk_mq_sched_insert_request(rq
, false, false, false, true);
576 blk_mq_run_hw_queues(q
, false);
579 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
580 bool kick_requeue_list
)
582 struct request_queue
*q
= rq
->q
;
586 * We abuse this flag that is otherwise used by the I/O scheduler to
587 * request head insertation from the workqueue.
589 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
591 spin_lock_irqsave(&q
->requeue_lock
, flags
);
593 rq
->rq_flags
|= RQF_SOFTBARRIER
;
594 list_add(&rq
->queuelist
, &q
->requeue_list
);
596 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
598 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
600 if (kick_requeue_list
)
601 blk_mq_kick_requeue_list(q
);
603 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
605 void blk_mq_kick_requeue_list(struct request_queue
*q
)
607 kblockd_schedule_delayed_work(&q
->requeue_work
, 0);
609 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
611 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
614 kblockd_schedule_delayed_work(&q
->requeue_work
,
615 msecs_to_jiffies(msecs
));
617 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
619 void blk_mq_abort_requeue_list(struct request_queue
*q
)
624 spin_lock_irqsave(&q
->requeue_lock
, flags
);
625 list_splice_init(&q
->requeue_list
, &rq_list
);
626 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
628 while (!list_empty(&rq_list
)) {
631 rq
= list_first_entry(&rq_list
, struct request
, queuelist
);
632 list_del_init(&rq
->queuelist
);
634 blk_mq_end_request(rq
, rq
->errors
);
637 EXPORT_SYMBOL(blk_mq_abort_requeue_list
);
639 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
641 if (tag
< tags
->nr_tags
) {
642 prefetch(tags
->rqs
[tag
]);
643 return tags
->rqs
[tag
];
648 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
650 struct blk_mq_timeout_data
{
652 unsigned int next_set
;
655 void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
657 const struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
658 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
661 * We know that complete is set at this point. If STARTED isn't set
662 * anymore, then the request isn't active and the "timeout" should
663 * just be ignored. This can happen due to the bitflag ordering.
664 * Timeout first checks if STARTED is set, and if it is, assumes
665 * the request is active. But if we race with completion, then
666 * we both flags will get cleared. So check here again, and ignore
667 * a timeout event with a request that isn't active.
669 if (!test_bit(REQ_ATOM_STARTED
, &req
->atomic_flags
))
673 ret
= ops
->timeout(req
, reserved
);
677 __blk_mq_complete_request(req
);
679 case BLK_EH_RESET_TIMER
:
681 blk_clear_rq_complete(req
);
683 case BLK_EH_NOT_HANDLED
:
686 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
691 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
692 struct request
*rq
, void *priv
, bool reserved
)
694 struct blk_mq_timeout_data
*data
= priv
;
696 if (!test_bit(REQ_ATOM_STARTED
, &rq
->atomic_flags
)) {
698 * If a request wasn't started before the queue was
699 * marked dying, kill it here or it'll go unnoticed.
701 if (unlikely(blk_queue_dying(rq
->q
))) {
703 blk_mq_end_request(rq
, rq
->errors
);
708 if (time_after_eq(jiffies
, rq
->deadline
)) {
709 if (!blk_mark_rq_complete(rq
))
710 blk_mq_rq_timed_out(rq
, reserved
);
711 } else if (!data
->next_set
|| time_after(data
->next
, rq
->deadline
)) {
712 data
->next
= rq
->deadline
;
717 static void blk_mq_timeout_work(struct work_struct
*work
)
719 struct request_queue
*q
=
720 container_of(work
, struct request_queue
, timeout_work
);
721 struct blk_mq_timeout_data data
= {
727 /* A deadlock might occur if a request is stuck requiring a
728 * timeout at the same time a queue freeze is waiting
729 * completion, since the timeout code would not be able to
730 * acquire the queue reference here.
732 * That's why we don't use blk_queue_enter here; instead, we use
733 * percpu_ref_tryget directly, because we need to be able to
734 * obtain a reference even in the short window between the queue
735 * starting to freeze, by dropping the first reference in
736 * blk_mq_freeze_queue_start, and the moment the last request is
737 * consumed, marked by the instant q_usage_counter reaches
740 if (!percpu_ref_tryget(&q
->q_usage_counter
))
743 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
746 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
747 mod_timer(&q
->timeout
, data
.next
);
749 struct blk_mq_hw_ctx
*hctx
;
751 queue_for_each_hw_ctx(q
, hctx
, i
) {
752 /* the hctx may be unmapped, so check it here */
753 if (blk_mq_hw_queue_mapped(hctx
))
754 blk_mq_tag_idle(hctx
);
761 * Reverse check our software queue for entries that we could potentially
762 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
763 * too much time checking for merges.
765 static bool blk_mq_attempt_merge(struct request_queue
*q
,
766 struct blk_mq_ctx
*ctx
, struct bio
*bio
)
771 list_for_each_entry_reverse(rq
, &ctx
->rq_list
, queuelist
) {
777 if (!blk_rq_merge_ok(rq
, bio
))
780 switch (blk_try_merge(rq
, bio
)) {
781 case ELEVATOR_BACK_MERGE
:
782 if (blk_mq_sched_allow_merge(q
, rq
, bio
))
783 merged
= bio_attempt_back_merge(q
, rq
, bio
);
785 case ELEVATOR_FRONT_MERGE
:
786 if (blk_mq_sched_allow_merge(q
, rq
, bio
))
787 merged
= bio_attempt_front_merge(q
, rq
, bio
);
789 case ELEVATOR_DISCARD_MERGE
:
790 merged
= bio_attempt_discard_merge(q
, rq
, bio
);
804 struct flush_busy_ctx_data
{
805 struct blk_mq_hw_ctx
*hctx
;
806 struct list_head
*list
;
809 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
811 struct flush_busy_ctx_data
*flush_data
= data
;
812 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
813 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
815 sbitmap_clear_bit(sb
, bitnr
);
816 spin_lock(&ctx
->lock
);
817 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
818 spin_unlock(&ctx
->lock
);
823 * Process software queues that have been marked busy, splicing them
824 * to the for-dispatch
826 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
828 struct flush_busy_ctx_data data
= {
833 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
835 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
837 static inline unsigned int queued_to_index(unsigned int queued
)
842 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
845 bool blk_mq_get_driver_tag(struct request
*rq
, struct blk_mq_hw_ctx
**hctx
,
848 struct blk_mq_alloc_data data
= {
850 .hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
),
851 .flags
= wait
? 0 : BLK_MQ_REQ_NOWAIT
,
861 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
862 data
.flags
|= BLK_MQ_REQ_RESERVED
;
864 rq
->tag
= blk_mq_get_tag(&data
);
866 if (blk_mq_tag_busy(data
.hctx
)) {
867 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
868 atomic_inc(&data
.hctx
->nr_active
);
870 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
877 static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx
*hctx
,
880 blk_mq_put_tag(hctx
, hctx
->tags
, rq
->mq_ctx
, rq
->tag
);
883 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
) {
884 rq
->rq_flags
&= ~RQF_MQ_INFLIGHT
;
885 atomic_dec(&hctx
->nr_active
);
889 static void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx
*hctx
,
892 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
895 __blk_mq_put_driver_tag(hctx
, rq
);
898 static void blk_mq_put_driver_tag(struct request
*rq
)
900 struct blk_mq_hw_ctx
*hctx
;
902 if (rq
->tag
== -1 || rq
->internal_tag
== -1)
905 hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
);
906 __blk_mq_put_driver_tag(hctx
, rq
);
910 * If we fail getting a driver tag because all the driver tags are already
911 * assigned and on the dispatch list, BUT the first entry does not have a
912 * tag, then we could deadlock. For that case, move entries with assigned
913 * driver tags to the front, leaving the set of tagged requests in the
914 * same order, and the untagged set in the same order.
916 static bool reorder_tags_to_front(struct list_head
*list
)
918 struct request
*rq
, *tmp
, *first
= NULL
;
920 list_for_each_entry_safe_reverse(rq
, tmp
, list
, queuelist
) {
924 list_move(&rq
->queuelist
, list
);
930 return first
!= NULL
;
933 static int blk_mq_dispatch_wake(wait_queue_t
*wait
, unsigned mode
, int flags
,
936 struct blk_mq_hw_ctx
*hctx
;
938 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
940 list_del(&wait
->task_list
);
941 clear_bit_unlock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
);
942 blk_mq_run_hw_queue(hctx
, true);
946 static bool blk_mq_dispatch_wait_add(struct blk_mq_hw_ctx
*hctx
)
948 struct sbq_wait_state
*ws
;
951 * The TAG_WAITING bit serves as a lock protecting hctx->dispatch_wait.
952 * The thread which wins the race to grab this bit adds the hardware
953 * queue to the wait queue.
955 if (test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
) ||
956 test_and_set_bit_lock(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
959 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
960 ws
= bt_wait_ptr(&hctx
->tags
->bitmap_tags
, hctx
);
963 * As soon as this returns, it's no longer safe to fiddle with
964 * hctx->dispatch_wait, since a completion can wake up the wait queue
965 * and unlock the bit.
967 add_wait_queue(&ws
->wait
, &hctx
->dispatch_wait
);
971 bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
973 struct request_queue
*q
= hctx
->queue
;
975 LIST_HEAD(driver_list
);
976 struct list_head
*dptr
;
977 int queued
, ret
= BLK_MQ_RQ_QUEUE_OK
;
980 * Start off with dptr being NULL, so we start the first request
981 * immediately, even if we have more pending.
986 * Now process all the entries, sending them to the driver.
989 while (!list_empty(list
)) {
990 struct blk_mq_queue_data bd
;
992 rq
= list_first_entry(list
, struct request
, queuelist
);
993 if (!blk_mq_get_driver_tag(rq
, &hctx
, false)) {
994 if (!queued
&& reorder_tags_to_front(list
))
998 * The initial allocation attempt failed, so we need to
999 * rerun the hardware queue when a tag is freed.
1001 if (blk_mq_dispatch_wait_add(hctx
)) {
1003 * It's possible that a tag was freed in the
1004 * window between the allocation failure and
1005 * adding the hardware queue to the wait queue.
1007 if (!blk_mq_get_driver_tag(rq
, &hctx
, false))
1014 list_del_init(&rq
->queuelist
);
1020 * Flag last if we have no more requests, or if we have more
1021 * but can't assign a driver tag to it.
1023 if (list_empty(list
))
1026 struct request
*nxt
;
1028 nxt
= list_first_entry(list
, struct request
, queuelist
);
1029 bd
.last
= !blk_mq_get_driver_tag(nxt
, NULL
, false);
1032 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1034 case BLK_MQ_RQ_QUEUE_OK
:
1037 case BLK_MQ_RQ_QUEUE_BUSY
:
1038 blk_mq_put_driver_tag_hctx(hctx
, rq
);
1039 list_add(&rq
->queuelist
, list
);
1040 __blk_mq_requeue_request(rq
);
1043 pr_err("blk-mq: bad return on queue: %d\n", ret
);
1044 case BLK_MQ_RQ_QUEUE_ERROR
:
1046 blk_mq_end_request(rq
, rq
->errors
);
1050 if (ret
== BLK_MQ_RQ_QUEUE_BUSY
)
1054 * We've done the first request. If we have more than 1
1055 * left in the list, set dptr to defer issue.
1057 if (!dptr
&& list
->next
!= list
->prev
)
1058 dptr
= &driver_list
;
1061 hctx
->dispatched
[queued_to_index(queued
)]++;
1064 * Any items that need requeuing? Stuff them into hctx->dispatch,
1065 * that is where we will continue on next queue run.
1067 if (!list_empty(list
)) {
1069 * If we got a driver tag for the next request already,
1072 rq
= list_first_entry(list
, struct request
, queuelist
);
1073 blk_mq_put_driver_tag(rq
);
1075 spin_lock(&hctx
->lock
);
1076 list_splice_init(list
, &hctx
->dispatch
);
1077 spin_unlock(&hctx
->lock
);
1080 * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
1081 * it's possible the queue is stopped and restarted again
1082 * before this. Queue restart will dispatch requests. And since
1083 * requests in rq_list aren't added into hctx->dispatch yet,
1084 * the requests in rq_list might get lost.
1086 * blk_mq_run_hw_queue() already checks the STOPPED bit
1088 * If RESTART or TAG_WAITING is set, then let completion restart
1089 * the queue instead of potentially looping here.
1091 if (!blk_mq_sched_needs_restart(hctx
) &&
1092 !test_bit(BLK_MQ_S_TAG_WAITING
, &hctx
->state
))
1093 blk_mq_run_hw_queue(hctx
, true);
1099 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1103 WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1104 cpu_online(hctx
->next_cpu
));
1106 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1108 blk_mq_sched_dispatch_requests(hctx
);
1111 srcu_idx
= srcu_read_lock(&hctx
->queue_rq_srcu
);
1112 blk_mq_sched_dispatch_requests(hctx
);
1113 srcu_read_unlock(&hctx
->queue_rq_srcu
, srcu_idx
);
1118 * It'd be great if the workqueue API had a way to pass
1119 * in a mask and had some smarts for more clever placement.
1120 * For now we just round-robin here, switching for every
1121 * BLK_MQ_CPU_WORK_BATCH queued items.
1123 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1125 if (hctx
->queue
->nr_hw_queues
== 1)
1126 return WORK_CPU_UNBOUND
;
1128 if (--hctx
->next_cpu_batch
<= 0) {
1131 next_cpu
= cpumask_next(hctx
->next_cpu
, hctx
->cpumask
);
1132 if (next_cpu
>= nr_cpu_ids
)
1133 next_cpu
= cpumask_first(hctx
->cpumask
);
1135 hctx
->next_cpu
= next_cpu
;
1136 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1139 return hctx
->next_cpu
;
1142 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1144 if (unlikely(blk_mq_hctx_stopped(hctx
) ||
1145 !blk_mq_hw_queue_mapped(hctx
)))
1148 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1149 int cpu
= get_cpu();
1150 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1151 __blk_mq_run_hw_queue(hctx
);
1159 kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
);
1162 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1164 struct blk_mq_hw_ctx
*hctx
;
1167 queue_for_each_hw_ctx(q
, hctx
, i
) {
1168 if (!blk_mq_hctx_has_pending(hctx
) ||
1169 blk_mq_hctx_stopped(hctx
))
1172 blk_mq_run_hw_queue(hctx
, async
);
1175 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1178 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1179 * @q: request queue.
1181 * The caller is responsible for serializing this function against
1182 * blk_mq_{start,stop}_hw_queue().
1184 bool blk_mq_queue_stopped(struct request_queue
*q
)
1186 struct blk_mq_hw_ctx
*hctx
;
1189 queue_for_each_hw_ctx(q
, hctx
, i
)
1190 if (blk_mq_hctx_stopped(hctx
))
1195 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1197 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1199 cancel_work(&hctx
->run_work
);
1200 cancel_delayed_work(&hctx
->delay_work
);
1201 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1203 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1205 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1207 struct blk_mq_hw_ctx
*hctx
;
1210 queue_for_each_hw_ctx(q
, hctx
, i
)
1211 blk_mq_stop_hw_queue(hctx
);
1213 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1215 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1217 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1219 blk_mq_run_hw_queue(hctx
, false);
1221 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1223 void blk_mq_start_hw_queues(struct request_queue
*q
)
1225 struct blk_mq_hw_ctx
*hctx
;
1228 queue_for_each_hw_ctx(q
, hctx
, i
)
1229 blk_mq_start_hw_queue(hctx
);
1231 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1233 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1235 if (!blk_mq_hctx_stopped(hctx
))
1238 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1239 blk_mq_run_hw_queue(hctx
, async
);
1241 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1243 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1245 struct blk_mq_hw_ctx
*hctx
;
1248 queue_for_each_hw_ctx(q
, hctx
, i
)
1249 blk_mq_start_stopped_hw_queue(hctx
, async
);
1251 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1253 static void blk_mq_run_work_fn(struct work_struct
*work
)
1255 struct blk_mq_hw_ctx
*hctx
;
1257 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
);
1259 __blk_mq_run_hw_queue(hctx
);
1262 static void blk_mq_delay_work_fn(struct work_struct
*work
)
1264 struct blk_mq_hw_ctx
*hctx
;
1266 hctx
= container_of(work
, struct blk_mq_hw_ctx
, delay_work
.work
);
1268 if (test_and_clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
1269 __blk_mq_run_hw_queue(hctx
);
1272 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1274 if (unlikely(!blk_mq_hw_queue_mapped(hctx
)))
1277 blk_mq_stop_hw_queue(hctx
);
1278 kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1279 &hctx
->delay_work
, msecs_to_jiffies(msecs
));
1281 EXPORT_SYMBOL(blk_mq_delay_queue
);
1283 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1287 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1289 trace_block_rq_insert(hctx
->queue
, rq
);
1292 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1294 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1297 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1300 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1302 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1303 blk_mq_hctx_mark_pending(hctx
, ctx
);
1306 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1307 struct list_head
*list
)
1311 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1314 spin_lock(&ctx
->lock
);
1315 while (!list_empty(list
)) {
1318 rq
= list_first_entry(list
, struct request
, queuelist
);
1319 BUG_ON(rq
->mq_ctx
!= ctx
);
1320 list_del_init(&rq
->queuelist
);
1321 __blk_mq_insert_req_list(hctx
, rq
, false);
1323 blk_mq_hctx_mark_pending(hctx
, ctx
);
1324 spin_unlock(&ctx
->lock
);
1327 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1329 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1330 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1332 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1333 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1334 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1337 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1339 struct blk_mq_ctx
*this_ctx
;
1340 struct request_queue
*this_q
;
1343 LIST_HEAD(ctx_list
);
1346 list_splice_init(&plug
->mq_list
, &list
);
1348 list_sort(NULL
, &list
, plug_ctx_cmp
);
1354 while (!list_empty(&list
)) {
1355 rq
= list_entry_rq(list
.next
);
1356 list_del_init(&rq
->queuelist
);
1358 if (rq
->mq_ctx
!= this_ctx
) {
1360 trace_block_unplug(this_q
, depth
, from_schedule
);
1361 blk_mq_sched_insert_requests(this_q
, this_ctx
,
1366 this_ctx
= rq
->mq_ctx
;
1372 list_add_tail(&rq
->queuelist
, &ctx_list
);
1376 * If 'this_ctx' is set, we know we have entries to complete
1377 * on 'ctx_list'. Do those.
1380 trace_block_unplug(this_q
, depth
, from_schedule
);
1381 blk_mq_sched_insert_requests(this_q
, this_ctx
, &ctx_list
,
1386 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1388 init_request_from_bio(rq
, bio
);
1390 blk_account_io_start(rq
, true);
1393 static inline bool hctx_allow_merges(struct blk_mq_hw_ctx
*hctx
)
1395 return (hctx
->flags
& BLK_MQ_F_SHOULD_MERGE
) &&
1396 !blk_queue_nomerges(hctx
->queue
);
1399 static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx
*hctx
,
1400 struct blk_mq_ctx
*ctx
,
1401 struct request
*rq
, struct bio
*bio
)
1403 if (!hctx_allow_merges(hctx
) || !bio_mergeable(bio
)) {
1404 blk_mq_bio_to_request(rq
, bio
);
1405 spin_lock(&ctx
->lock
);
1407 __blk_mq_insert_request(hctx
, rq
, false);
1408 spin_unlock(&ctx
->lock
);
1411 struct request_queue
*q
= hctx
->queue
;
1413 spin_lock(&ctx
->lock
);
1414 if (!blk_mq_attempt_merge(q
, ctx
, bio
)) {
1415 blk_mq_bio_to_request(rq
, bio
);
1419 spin_unlock(&ctx
->lock
);
1420 __blk_mq_finish_request(hctx
, ctx
, rq
);
1425 static blk_qc_t
request_to_qc_t(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
1428 return blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
, false);
1430 return blk_tag_to_qc_t(rq
->internal_tag
, hctx
->queue_num
, true);
1433 static void blk_mq_try_issue_directly(struct request
*rq
, blk_qc_t
*cookie
,
1436 struct request_queue
*q
= rq
->q
;
1437 struct blk_mq_queue_data bd
= {
1442 struct blk_mq_hw_ctx
*hctx
;
1443 blk_qc_t new_cookie
;
1449 if (!blk_mq_get_driver_tag(rq
, &hctx
, false))
1452 new_cookie
= request_to_qc_t(hctx
, rq
);
1455 * For OK queue, we are done. For error, kill it. Any other
1456 * error (busy), just add it to our list as we previously
1459 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1460 if (ret
== BLK_MQ_RQ_QUEUE_OK
) {
1461 *cookie
= new_cookie
;
1465 __blk_mq_requeue_request(rq
);
1467 if (ret
== BLK_MQ_RQ_QUEUE_ERROR
) {
1468 *cookie
= BLK_QC_T_NONE
;
1470 blk_mq_end_request(rq
, rq
->errors
);
1475 blk_mq_sched_insert_request(rq
, false, true, false, may_sleep
);
1479 * Multiple hardware queue variant. This will not use per-process plugs,
1480 * but will attempt to bypass the hctx queueing if we can go straight to
1481 * hardware for SYNC IO.
1483 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1485 const int is_sync
= op_is_sync(bio
->bi_opf
);
1486 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1487 struct blk_mq_alloc_data data
= { .flags
= 0 };
1489 unsigned int request_count
= 0, srcu_idx
;
1490 struct blk_plug
*plug
;
1491 struct request
*same_queue_rq
= NULL
;
1493 unsigned int wb_acct
;
1495 blk_queue_bounce(q
, &bio
);
1497 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1499 return BLK_QC_T_NONE
;
1502 blk_queue_split(q
, &bio
, q
->bio_split
);
1504 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1505 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1506 return BLK_QC_T_NONE
;
1508 if (blk_mq_sched_bio_merge(q
, bio
))
1509 return BLK_QC_T_NONE
;
1511 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1513 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1515 rq
= blk_mq_sched_get_request(q
, bio
, bio
->bi_opf
, &data
);
1516 if (unlikely(!rq
)) {
1517 __wbt_done(q
->rq_wb
, wb_acct
);
1518 return BLK_QC_T_NONE
;
1521 wbt_track(&rq
->issue_stat
, wb_acct
);
1523 cookie
= request_to_qc_t(data
.hctx
, rq
);
1525 if (unlikely(is_flush_fua
)) {
1528 blk_mq_bio_to_request(rq
, bio
);
1529 blk_insert_flush(rq
);
1533 plug
= current
->plug
;
1535 * If the driver supports defer issued based on 'last', then
1536 * queue it up like normal since we can potentially save some
1539 if (((plug
&& !blk_queue_nomerges(q
)) || is_sync
) &&
1540 !(data
.hctx
->flags
& BLK_MQ_F_DEFER_ISSUE
)) {
1541 struct request
*old_rq
= NULL
;
1543 blk_mq_bio_to_request(rq
, bio
);
1546 * We do limited plugging. If the bio can be merged, do that.
1547 * Otherwise the existing request in the plug list will be
1548 * issued. So the plug list will have one request at most
1552 * The plug list might get flushed before this. If that
1553 * happens, same_queue_rq is invalid and plug list is
1556 if (same_queue_rq
&& !list_empty(&plug
->mq_list
)) {
1557 old_rq
= same_queue_rq
;
1558 list_del_init(&old_rq
->queuelist
);
1560 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1561 } else /* is_sync */
1563 blk_mq_put_ctx(data
.ctx
);
1567 if (!(data
.hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1569 blk_mq_try_issue_directly(old_rq
, &cookie
, false);
1572 srcu_idx
= srcu_read_lock(&data
.hctx
->queue_rq_srcu
);
1573 blk_mq_try_issue_directly(old_rq
, &cookie
, true);
1574 srcu_read_unlock(&data
.hctx
->queue_rq_srcu
, srcu_idx
);
1581 blk_mq_put_ctx(data
.ctx
);
1582 blk_mq_bio_to_request(rq
, bio
);
1583 blk_mq_sched_insert_request(rq
, false, true,
1584 !is_sync
|| is_flush_fua
, true);
1587 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1589 * For a SYNC request, send it to the hardware immediately. For
1590 * an ASYNC request, just ensure that we run it later on. The
1591 * latter allows for merging opportunities and more efficient
1595 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1597 blk_mq_put_ctx(data
.ctx
);
1603 * Single hardware queue variant. This will attempt to use any per-process
1604 * plug for merging and IO deferral.
1606 static blk_qc_t
blk_sq_make_request(struct request_queue
*q
, struct bio
*bio
)
1608 const int is_sync
= op_is_sync(bio
->bi_opf
);
1609 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1610 struct blk_plug
*plug
;
1611 unsigned int request_count
= 0;
1612 struct blk_mq_alloc_data data
= { .flags
= 0 };
1615 unsigned int wb_acct
;
1617 blk_queue_bounce(q
, &bio
);
1619 if (bio_integrity_enabled(bio
) && bio_integrity_prep(bio
)) {
1621 return BLK_QC_T_NONE
;
1624 blk_queue_split(q
, &bio
, q
->bio_split
);
1626 if (!is_flush_fua
&& !blk_queue_nomerges(q
)) {
1627 if (blk_attempt_plug_merge(q
, bio
, &request_count
, NULL
))
1628 return BLK_QC_T_NONE
;
1630 request_count
= blk_plug_queued_count(q
);
1632 if (blk_mq_sched_bio_merge(q
, bio
))
1633 return BLK_QC_T_NONE
;
1635 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1637 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1639 rq
= blk_mq_sched_get_request(q
, bio
, bio
->bi_opf
, &data
);
1640 if (unlikely(!rq
)) {
1641 __wbt_done(q
->rq_wb
, wb_acct
);
1642 return BLK_QC_T_NONE
;
1645 wbt_track(&rq
->issue_stat
, wb_acct
);
1647 cookie
= request_to_qc_t(data
.hctx
, rq
);
1649 if (unlikely(is_flush_fua
)) {
1652 blk_mq_bio_to_request(rq
, bio
);
1653 blk_insert_flush(rq
);
1658 * A task plug currently exists. Since this is completely lockless,
1659 * utilize that to temporarily store requests until the task is
1660 * either done or scheduled away.
1662 plug
= current
->plug
;
1664 struct request
*last
= NULL
;
1666 blk_mq_bio_to_request(rq
, bio
);
1669 * @request_count may become stale because of schedule
1670 * out, so check the list again.
1672 if (list_empty(&plug
->mq_list
))
1675 trace_block_plug(q
);
1677 last
= list_entry_rq(plug
->mq_list
.prev
);
1679 blk_mq_put_ctx(data
.ctx
);
1681 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1682 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1683 blk_flush_plug_list(plug
, false);
1684 trace_block_plug(q
);
1687 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1693 blk_mq_put_ctx(data
.ctx
);
1694 blk_mq_bio_to_request(rq
, bio
);
1695 blk_mq_sched_insert_request(rq
, false, true,
1696 !is_sync
|| is_flush_fua
, true);
1699 if (!blk_mq_merge_queue_io(data
.hctx
, data
.ctx
, rq
, bio
)) {
1701 * For a SYNC request, send it to the hardware immediately. For
1702 * an ASYNC request, just ensure that we run it later on. The
1703 * latter allows for merging opportunities and more efficient
1707 blk_mq_run_hw_queue(data
.hctx
, !is_sync
|| is_flush_fua
);
1710 blk_mq_put_ctx(data
.ctx
);
1715 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1716 unsigned int hctx_idx
)
1720 if (tags
->rqs
&& set
->ops
->exit_request
) {
1723 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1724 struct request
*rq
= tags
->static_rqs
[i
];
1728 set
->ops
->exit_request(set
->driver_data
, rq
,
1730 tags
->static_rqs
[i
] = NULL
;
1734 while (!list_empty(&tags
->page_list
)) {
1735 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1736 list_del_init(&page
->lru
);
1738 * Remove kmemleak object previously allocated in
1739 * blk_mq_init_rq_map().
1741 kmemleak_free(page_address(page
));
1742 __free_pages(page
, page
->private);
1746 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
1750 kfree(tags
->static_rqs
);
1751 tags
->static_rqs
= NULL
;
1753 blk_mq_free_tags(tags
);
1756 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
1757 unsigned int hctx_idx
,
1758 unsigned int nr_tags
,
1759 unsigned int reserved_tags
)
1761 struct blk_mq_tags
*tags
;
1764 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1765 if (node
== NUMA_NO_NODE
)
1766 node
= set
->numa_node
;
1768 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
1769 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
1773 tags
->rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1774 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1777 blk_mq_free_tags(tags
);
1781 tags
->static_rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
1782 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
1784 if (!tags
->static_rqs
) {
1786 blk_mq_free_tags(tags
);
1793 static size_t order_to_size(unsigned int order
)
1795 return (size_t)PAGE_SIZE
<< order
;
1798 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1799 unsigned int hctx_idx
, unsigned int depth
)
1801 unsigned int i
, j
, entries_per_page
, max_order
= 4;
1802 size_t rq_size
, left
;
1805 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
1806 if (node
== NUMA_NO_NODE
)
1807 node
= set
->numa_node
;
1809 INIT_LIST_HEAD(&tags
->page_list
);
1812 * rq_size is the size of the request plus driver payload, rounded
1813 * to the cacheline size
1815 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
1817 left
= rq_size
* depth
;
1819 for (i
= 0; i
< depth
; ) {
1820 int this_order
= max_order
;
1825 while (this_order
&& left
< order_to_size(this_order
- 1))
1829 page
= alloc_pages_node(node
,
1830 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
1836 if (order_to_size(this_order
) < rq_size
)
1843 page
->private = this_order
;
1844 list_add_tail(&page
->lru
, &tags
->page_list
);
1846 p
= page_address(page
);
1848 * Allow kmemleak to scan these pages as they contain pointers
1849 * to additional allocations like via ops->init_request().
1851 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
1852 entries_per_page
= order_to_size(this_order
) / rq_size
;
1853 to_do
= min(entries_per_page
, depth
- i
);
1854 left
-= to_do
* rq_size
;
1855 for (j
= 0; j
< to_do
; j
++) {
1856 struct request
*rq
= p
;
1858 tags
->static_rqs
[i
] = rq
;
1859 if (set
->ops
->init_request
) {
1860 if (set
->ops
->init_request(set
->driver_data
,
1863 tags
->static_rqs
[i
] = NULL
;
1875 blk_mq_free_rqs(set
, tags
, hctx_idx
);
1880 * 'cpu' is going away. splice any existing rq_list entries from this
1881 * software queue to the hw queue dispatch list, and ensure that it
1884 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
1886 struct blk_mq_hw_ctx
*hctx
;
1887 struct blk_mq_ctx
*ctx
;
1890 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
1891 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
1893 spin_lock(&ctx
->lock
);
1894 if (!list_empty(&ctx
->rq_list
)) {
1895 list_splice_init(&ctx
->rq_list
, &tmp
);
1896 blk_mq_hctx_clear_pending(hctx
, ctx
);
1898 spin_unlock(&ctx
->lock
);
1900 if (list_empty(&tmp
))
1903 spin_lock(&hctx
->lock
);
1904 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
1905 spin_unlock(&hctx
->lock
);
1907 blk_mq_run_hw_queue(hctx
, true);
1911 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
1913 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
1917 /* hctx->ctxs will be freed in queue's release handler */
1918 static void blk_mq_exit_hctx(struct request_queue
*q
,
1919 struct blk_mq_tag_set
*set
,
1920 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
1922 unsigned flush_start_tag
= set
->queue_depth
;
1924 blk_mq_tag_idle(hctx
);
1926 if (set
->ops
->exit_request
)
1927 set
->ops
->exit_request(set
->driver_data
,
1928 hctx
->fq
->flush_rq
, hctx_idx
,
1929 flush_start_tag
+ hctx_idx
);
1931 if (set
->ops
->exit_hctx
)
1932 set
->ops
->exit_hctx(hctx
, hctx_idx
);
1934 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
1935 cleanup_srcu_struct(&hctx
->queue_rq_srcu
);
1937 blk_mq_remove_cpuhp(hctx
);
1938 blk_free_flush_queue(hctx
->fq
);
1939 sbitmap_free(&hctx
->ctx_map
);
1942 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
1943 struct blk_mq_tag_set
*set
, int nr_queue
)
1945 struct blk_mq_hw_ctx
*hctx
;
1948 queue_for_each_hw_ctx(q
, hctx
, i
) {
1951 blk_mq_exit_hctx(q
, set
, hctx
, i
);
1955 static int blk_mq_init_hctx(struct request_queue
*q
,
1956 struct blk_mq_tag_set
*set
,
1957 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
1960 unsigned flush_start_tag
= set
->queue_depth
;
1962 node
= hctx
->numa_node
;
1963 if (node
== NUMA_NO_NODE
)
1964 node
= hctx
->numa_node
= set
->numa_node
;
1966 INIT_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
1967 INIT_DELAYED_WORK(&hctx
->delay_work
, blk_mq_delay_work_fn
);
1968 spin_lock_init(&hctx
->lock
);
1969 INIT_LIST_HEAD(&hctx
->dispatch
);
1971 hctx
->queue_num
= hctx_idx
;
1972 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
1974 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
1976 hctx
->tags
= set
->tags
[hctx_idx
];
1979 * Allocate space for all possible cpus to avoid allocation at
1982 hctx
->ctxs
= kmalloc_node(nr_cpu_ids
* sizeof(void *),
1985 goto unregister_cpu_notifier
;
1987 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
1993 if (set
->ops
->init_hctx
&&
1994 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
1997 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
2001 if (set
->ops
->init_request
&&
2002 set
->ops
->init_request(set
->driver_data
,
2003 hctx
->fq
->flush_rq
, hctx_idx
,
2004 flush_start_tag
+ hctx_idx
, node
))
2007 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2008 init_srcu_struct(&hctx
->queue_rq_srcu
);
2015 if (set
->ops
->exit_hctx
)
2016 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2018 sbitmap_free(&hctx
->ctx_map
);
2021 unregister_cpu_notifier
:
2022 blk_mq_remove_cpuhp(hctx
);
2026 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2027 unsigned int nr_hw_queues
)
2031 for_each_possible_cpu(i
) {
2032 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2033 struct blk_mq_hw_ctx
*hctx
;
2036 spin_lock_init(&__ctx
->lock
);
2037 INIT_LIST_HEAD(&__ctx
->rq_list
);
2040 /* If the cpu isn't online, the cpu is mapped to first hctx */
2044 hctx
= blk_mq_map_queue(q
, i
);
2047 * Set local node, IFF we have more than one hw queue. If
2048 * not, we remain on the home node of the device
2050 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2051 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2055 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2059 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2060 set
->queue_depth
, set
->reserved_tags
);
2061 if (!set
->tags
[hctx_idx
])
2064 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2069 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2070 set
->tags
[hctx_idx
] = NULL
;
2074 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2075 unsigned int hctx_idx
)
2077 if (set
->tags
[hctx_idx
]) {
2078 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2079 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2080 set
->tags
[hctx_idx
] = NULL
;
2084 static void blk_mq_map_swqueue(struct request_queue
*q
,
2085 const struct cpumask
*online_mask
)
2087 unsigned int i
, hctx_idx
;
2088 struct blk_mq_hw_ctx
*hctx
;
2089 struct blk_mq_ctx
*ctx
;
2090 struct blk_mq_tag_set
*set
= q
->tag_set
;
2093 * Avoid others reading imcomplete hctx->cpumask through sysfs
2095 mutex_lock(&q
->sysfs_lock
);
2097 queue_for_each_hw_ctx(q
, hctx
, i
) {
2098 cpumask_clear(hctx
->cpumask
);
2103 * Map software to hardware queues
2105 for_each_possible_cpu(i
) {
2106 /* If the cpu isn't online, the cpu is mapped to first hctx */
2107 if (!cpumask_test_cpu(i
, online_mask
))
2110 hctx_idx
= q
->mq_map
[i
];
2111 /* unmapped hw queue can be remapped after CPU topo changed */
2112 if (!set
->tags
[hctx_idx
] &&
2113 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2115 * If tags initialization fail for some hctx,
2116 * that hctx won't be brought online. In this
2117 * case, remap the current ctx to hctx[0] which
2118 * is guaranteed to always have tags allocated
2123 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2124 hctx
= blk_mq_map_queue(q
, i
);
2126 cpumask_set_cpu(i
, hctx
->cpumask
);
2127 ctx
->index_hw
= hctx
->nr_ctx
;
2128 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2131 mutex_unlock(&q
->sysfs_lock
);
2133 queue_for_each_hw_ctx(q
, hctx
, i
) {
2135 * If no software queues are mapped to this hardware queue,
2136 * disable it and free the request entries.
2138 if (!hctx
->nr_ctx
) {
2139 /* Never unmap queue 0. We need it as a
2140 * fallback in case of a new remap fails
2143 if (i
&& set
->tags
[i
])
2144 blk_mq_free_map_and_requests(set
, i
);
2150 hctx
->tags
= set
->tags
[i
];
2151 WARN_ON(!hctx
->tags
);
2154 * Set the map size to the number of mapped software queues.
2155 * This is more accurate and more efficient than looping
2156 * over all possibly mapped software queues.
2158 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2161 * Initialize batch roundrobin counts
2163 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
2164 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2168 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2170 struct blk_mq_hw_ctx
*hctx
;
2173 queue_for_each_hw_ctx(q
, hctx
, i
) {
2175 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2177 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2181 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
, bool shared
)
2183 struct request_queue
*q
;
2185 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2186 blk_mq_freeze_queue(q
);
2187 queue_set_hctx_shared(q
, shared
);
2188 blk_mq_unfreeze_queue(q
);
2192 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2194 struct blk_mq_tag_set
*set
= q
->tag_set
;
2196 mutex_lock(&set
->tag_list_lock
);
2197 list_del_init(&q
->tag_set_list
);
2198 if (list_is_singular(&set
->tag_list
)) {
2199 /* just transitioned to unshared */
2200 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2201 /* update existing queue */
2202 blk_mq_update_tag_set_depth(set
, false);
2204 mutex_unlock(&set
->tag_list_lock
);
2207 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2208 struct request_queue
*q
)
2212 mutex_lock(&set
->tag_list_lock
);
2214 /* Check to see if we're transitioning to shared (from 1 to 2 queues). */
2215 if (!list_empty(&set
->tag_list
) && !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2216 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2217 /* update existing queue */
2218 blk_mq_update_tag_set_depth(set
, true);
2220 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2221 queue_set_hctx_shared(q
, true);
2222 list_add_tail(&q
->tag_set_list
, &set
->tag_list
);
2224 mutex_unlock(&set
->tag_list_lock
);
2228 * It is the actual release handler for mq, but we do it from
2229 * request queue's release handler for avoiding use-after-free
2230 * and headache because q->mq_kobj shouldn't have been introduced,
2231 * but we can't group ctx/kctx kobj without it.
2233 void blk_mq_release(struct request_queue
*q
)
2235 struct blk_mq_hw_ctx
*hctx
;
2238 blk_mq_sched_teardown(q
);
2240 /* hctx kobj stays in hctx */
2241 queue_for_each_hw_ctx(q
, hctx
, i
) {
2244 kobject_put(&hctx
->kobj
);
2249 kfree(q
->queue_hw_ctx
);
2252 * release .mq_kobj and sw queue's kobject now because
2253 * both share lifetime with request queue.
2255 blk_mq_sysfs_deinit(q
);
2257 free_percpu(q
->queue_ctx
);
2260 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2262 struct request_queue
*uninit_q
, *q
;
2264 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2266 return ERR_PTR(-ENOMEM
);
2268 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2270 blk_cleanup_queue(uninit_q
);
2274 EXPORT_SYMBOL(blk_mq_init_queue
);
2276 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2277 struct request_queue
*q
)
2280 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2282 blk_mq_sysfs_unregister(q
);
2283 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2289 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
2290 hctxs
[i
] = kzalloc_node(sizeof(struct blk_mq_hw_ctx
),
2295 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
2302 atomic_set(&hctxs
[i
]->nr_active
, 0);
2303 hctxs
[i
]->numa_node
= node
;
2304 hctxs
[i
]->queue_num
= i
;
2306 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
2307 free_cpumask_var(hctxs
[i
]->cpumask
);
2312 blk_mq_hctx_kobj_init(hctxs
[i
]);
2314 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
2315 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2319 blk_mq_free_map_and_requests(set
, j
);
2320 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2321 kobject_put(&hctx
->kobj
);
2326 q
->nr_hw_queues
= i
;
2327 blk_mq_sysfs_register(q
);
2330 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2331 struct request_queue
*q
)
2333 /* mark the queue as mq asap */
2334 q
->mq_ops
= set
->ops
;
2336 q
->stats
= blk_alloc_queue_stats();
2340 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2341 blk_stat_rq_ddir
, 2, q
);
2345 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2349 /* init q->mq_kobj and sw queues' kobjects */
2350 blk_mq_sysfs_init(q
);
2352 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2353 GFP_KERNEL
, set
->numa_node
);
2354 if (!q
->queue_hw_ctx
)
2357 q
->mq_map
= set
->mq_map
;
2359 blk_mq_realloc_hw_ctxs(set
, q
);
2360 if (!q
->nr_hw_queues
)
2363 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2364 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2366 q
->nr_queues
= nr_cpu_ids
;
2368 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2370 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2371 q
->queue_flags
|= 1 << QUEUE_FLAG_NO_SG_MERGE
;
2373 q
->sg_reserved_size
= INT_MAX
;
2375 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2376 INIT_LIST_HEAD(&q
->requeue_list
);
2377 spin_lock_init(&q
->requeue_lock
);
2379 if (q
->nr_hw_queues
> 1)
2380 blk_queue_make_request(q
, blk_mq_make_request
);
2382 blk_queue_make_request(q
, blk_sq_make_request
);
2385 * Do this after blk_queue_make_request() overrides it...
2387 q
->nr_requests
= set
->queue_depth
;
2390 * Default to classic polling
2394 if (set
->ops
->complete
)
2395 blk_queue_softirq_done(q
, set
->ops
->complete
);
2397 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2400 mutex_lock(&all_q_mutex
);
2402 list_add_tail(&q
->all_q_node
, &all_q_list
);
2403 blk_mq_add_queue_tag_set(set
, q
);
2404 blk_mq_map_swqueue(q
, cpu_online_mask
);
2406 mutex_unlock(&all_q_mutex
);
2409 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2412 ret
= blk_mq_sched_init(q
);
2414 return ERR_PTR(ret
);
2420 kfree(q
->queue_hw_ctx
);
2422 free_percpu(q
->queue_ctx
);
2425 return ERR_PTR(-ENOMEM
);
2427 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2429 void blk_mq_free_queue(struct request_queue
*q
)
2431 struct blk_mq_tag_set
*set
= q
->tag_set
;
2433 mutex_lock(&all_q_mutex
);
2434 list_del_init(&q
->all_q_node
);
2435 mutex_unlock(&all_q_mutex
);
2437 blk_mq_del_queue_tag_set(q
);
2439 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2442 /* Basically redo blk_mq_init_queue with queue frozen */
2443 static void blk_mq_queue_reinit(struct request_queue
*q
,
2444 const struct cpumask
*online_mask
)
2446 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2448 blk_mq_sysfs_unregister(q
);
2451 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2452 * we should change hctx numa_node according to new topology (this
2453 * involves free and re-allocate memory, worthy doing?)
2456 blk_mq_map_swqueue(q
, online_mask
);
2458 blk_mq_sysfs_register(q
);
2462 * New online cpumask which is going to be set in this hotplug event.
2463 * Declare this cpumasks as global as cpu-hotplug operation is invoked
2464 * one-by-one and dynamically allocating this could result in a failure.
2466 static struct cpumask cpuhp_online_new
;
2468 static void blk_mq_queue_reinit_work(void)
2470 struct request_queue
*q
;
2472 mutex_lock(&all_q_mutex
);
2474 * We need to freeze and reinit all existing queues. Freezing
2475 * involves synchronous wait for an RCU grace period and doing it
2476 * one by one may take a long time. Start freezing all queues in
2477 * one swoop and then wait for the completions so that freezing can
2478 * take place in parallel.
2480 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2481 blk_mq_freeze_queue_start(q
);
2482 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2483 blk_mq_freeze_queue_wait(q
);
2485 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2486 blk_mq_queue_reinit(q
, &cpuhp_online_new
);
2488 list_for_each_entry(q
, &all_q_list
, all_q_node
)
2489 blk_mq_unfreeze_queue(q
);
2491 mutex_unlock(&all_q_mutex
);
2494 static int blk_mq_queue_reinit_dead(unsigned int cpu
)
2496 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2497 blk_mq_queue_reinit_work();
2502 * Before hotadded cpu starts handling requests, new mappings must be
2503 * established. Otherwise, these requests in hw queue might never be
2506 * For example, there is a single hw queue (hctx) and two CPU queues (ctx0
2507 * for CPU0, and ctx1 for CPU1).
2509 * Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
2510 * and set bit0 in pending bitmap as ctx1->index_hw is still zero.
2512 * And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
2513 * in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
2514 * But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
2517 static int blk_mq_queue_reinit_prepare(unsigned int cpu
)
2519 cpumask_copy(&cpuhp_online_new
, cpu_online_mask
);
2520 cpumask_set_cpu(cpu
, &cpuhp_online_new
);
2521 blk_mq_queue_reinit_work();
2525 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2529 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2530 if (!__blk_mq_alloc_rq_map(set
, i
))
2537 blk_mq_free_rq_map(set
->tags
[i
]);
2543 * Allocate the request maps associated with this tag_set. Note that this
2544 * may reduce the depth asked for, if memory is tight. set->queue_depth
2545 * will be updated to reflect the allocated depth.
2547 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2552 depth
= set
->queue_depth
;
2554 err
= __blk_mq_alloc_rq_maps(set
);
2558 set
->queue_depth
>>= 1;
2559 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2563 } while (set
->queue_depth
);
2565 if (!set
->queue_depth
|| err
) {
2566 pr_err("blk-mq: failed to allocate request map\n");
2570 if (depth
!= set
->queue_depth
)
2571 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2572 depth
, set
->queue_depth
);
2578 * Alloc a tag set to be associated with one or more request queues.
2579 * May fail with EINVAL for various error conditions. May adjust the
2580 * requested depth down, if if it too large. In that case, the set
2581 * value will be stored in set->queue_depth.
2583 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2587 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2589 if (!set
->nr_hw_queues
)
2591 if (!set
->queue_depth
)
2593 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2596 if (!set
->ops
->queue_rq
)
2599 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2600 pr_info("blk-mq: reduced tag depth to %u\n",
2602 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2606 * If a crashdump is active, then we are potentially in a very
2607 * memory constrained environment. Limit us to 1 queue and
2608 * 64 tags to prevent using too much memory.
2610 if (is_kdump_kernel()) {
2611 set
->nr_hw_queues
= 1;
2612 set
->queue_depth
= min(64U, set
->queue_depth
);
2615 * There is no use for more h/w queues than cpus.
2617 if (set
->nr_hw_queues
> nr_cpu_ids
)
2618 set
->nr_hw_queues
= nr_cpu_ids
;
2620 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2621 GFP_KERNEL
, set
->numa_node
);
2626 set
->mq_map
= kzalloc_node(sizeof(*set
->mq_map
) * nr_cpu_ids
,
2627 GFP_KERNEL
, set
->numa_node
);
2631 if (set
->ops
->map_queues
)
2632 ret
= set
->ops
->map_queues(set
);
2634 ret
= blk_mq_map_queues(set
);
2636 goto out_free_mq_map
;
2638 ret
= blk_mq_alloc_rq_maps(set
);
2640 goto out_free_mq_map
;
2642 mutex_init(&set
->tag_list_lock
);
2643 INIT_LIST_HEAD(&set
->tag_list
);
2655 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2657 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2661 for (i
= 0; i
< nr_cpu_ids
; i
++)
2662 blk_mq_free_map_and_requests(set
, i
);
2670 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2672 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2674 struct blk_mq_tag_set
*set
= q
->tag_set
;
2675 struct blk_mq_hw_ctx
*hctx
;
2681 blk_mq_freeze_queue(q
);
2682 blk_mq_quiesce_queue(q
);
2685 queue_for_each_hw_ctx(q
, hctx
, i
) {
2689 * If we're using an MQ scheduler, just update the scheduler
2690 * queue depth. This is similar to what the old code would do.
2692 if (!hctx
->sched_tags
) {
2693 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
,
2694 min(nr
, set
->queue_depth
),
2697 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
2705 q
->nr_requests
= nr
;
2707 blk_mq_unfreeze_queue(q
);
2708 blk_mq_start_stopped_hw_queues(q
, true);
2713 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2715 struct request_queue
*q
;
2717 if (nr_hw_queues
> nr_cpu_ids
)
2718 nr_hw_queues
= nr_cpu_ids
;
2719 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2722 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2723 blk_mq_freeze_queue(q
);
2725 set
->nr_hw_queues
= nr_hw_queues
;
2726 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2727 blk_mq_realloc_hw_ctxs(set
, q
);
2730 * Manually set the make_request_fn as blk_queue_make_request
2731 * resets a lot of the queue settings.
2733 if (q
->nr_hw_queues
> 1)
2734 q
->make_request_fn
= blk_mq_make_request
;
2736 q
->make_request_fn
= blk_sq_make_request
;
2738 blk_mq_queue_reinit(q
, cpu_online_mask
);
2741 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2742 blk_mq_unfreeze_queue(q
);
2744 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2746 /* Enable polling stats and return whether they were already enabled. */
2747 static bool blk_poll_stats_enable(struct request_queue
*q
)
2749 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2750 test_and_set_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
))
2752 blk_stat_add_callback(q
, q
->poll_cb
);
2756 static void blk_mq_poll_stats_start(struct request_queue
*q
)
2759 * We don't arm the callback if polling stats are not enabled or the
2760 * callback is already active.
2762 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
2763 blk_stat_is_active(q
->poll_cb
))
2766 blk_stat_activate_msecs(q
->poll_cb
, 100);
2769 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
2771 struct request_queue
*q
= cb
->data
;
2773 if (cb
->stat
[READ
].nr_samples
)
2774 q
->poll_stat
[READ
] = cb
->stat
[READ
];
2775 if (cb
->stat
[WRITE
].nr_samples
)
2776 q
->poll_stat
[WRITE
] = cb
->stat
[WRITE
];
2779 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
2780 struct blk_mq_hw_ctx
*hctx
,
2783 unsigned long ret
= 0;
2786 * If stats collection isn't on, don't sleep but turn it on for
2789 if (!blk_poll_stats_enable(q
))
2793 * As an optimistic guess, use half of the mean service time
2794 * for this type of request. We can (and should) make this smarter.
2795 * For instance, if the completion latencies are tight, we can
2796 * get closer than just half the mean. This is especially
2797 * important on devices where the completion latencies are longer
2800 if (req_op(rq
) == REQ_OP_READ
&& q
->poll_stat
[READ
].nr_samples
)
2801 ret
= (q
->poll_stat
[READ
].mean
+ 1) / 2;
2802 else if (req_op(rq
) == REQ_OP_WRITE
&& q
->poll_stat
[WRITE
].nr_samples
)
2803 ret
= (q
->poll_stat
[WRITE
].mean
+ 1) / 2;
2808 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
2809 struct blk_mq_hw_ctx
*hctx
,
2812 struct hrtimer_sleeper hs
;
2813 enum hrtimer_mode mode
;
2817 if (test_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
))
2823 * -1: don't ever hybrid sleep
2824 * 0: use half of prev avg
2825 * >0: use this specific value
2827 if (q
->poll_nsec
== -1)
2829 else if (q
->poll_nsec
> 0)
2830 nsecs
= q
->poll_nsec
;
2832 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
2837 set_bit(REQ_ATOM_POLL_SLEPT
, &rq
->atomic_flags
);
2840 * This will be replaced with the stats tracking code, using
2841 * 'avg_completion_time / 2' as the pre-sleep target.
2845 mode
= HRTIMER_MODE_REL
;
2846 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
2847 hrtimer_set_expires(&hs
.timer
, kt
);
2849 hrtimer_init_sleeper(&hs
, current
);
2851 if (test_bit(REQ_ATOM_COMPLETE
, &rq
->atomic_flags
))
2853 set_current_state(TASK_UNINTERRUPTIBLE
);
2854 hrtimer_start_expires(&hs
.timer
, mode
);
2857 hrtimer_cancel(&hs
.timer
);
2858 mode
= HRTIMER_MODE_ABS
;
2859 } while (hs
.task
&& !signal_pending(current
));
2861 __set_current_state(TASK_RUNNING
);
2862 destroy_hrtimer_on_stack(&hs
.timer
);
2866 static bool __blk_mq_poll(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
2868 struct request_queue
*q
= hctx
->queue
;
2872 * If we sleep, have the caller restart the poll loop to reset
2873 * the state. Like for the other success return cases, the
2874 * caller is responsible for checking if the IO completed. If
2875 * the IO isn't complete, we'll get called again and will go
2876 * straight to the busy poll loop.
2878 if (blk_mq_poll_hybrid_sleep(q
, hctx
, rq
))
2881 hctx
->poll_considered
++;
2883 state
= current
->state
;
2884 while (!need_resched()) {
2887 hctx
->poll_invoked
++;
2889 ret
= q
->mq_ops
->poll(hctx
, rq
->tag
);
2891 hctx
->poll_success
++;
2892 set_current_state(TASK_RUNNING
);
2896 if (signal_pending_state(state
, current
))
2897 set_current_state(TASK_RUNNING
);
2899 if (current
->state
== TASK_RUNNING
)
2909 bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
)
2911 struct blk_mq_hw_ctx
*hctx
;
2912 struct blk_plug
*plug
;
2915 if (!q
->mq_ops
|| !q
->mq_ops
->poll
|| !blk_qc_t_valid(cookie
) ||
2916 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
2919 plug
= current
->plug
;
2921 blk_flush_plug_list(plug
, false);
2923 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
2924 if (!blk_qc_t_is_internal(cookie
))
2925 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
2927 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
2929 return __blk_mq_poll(hctx
, rq
);
2931 EXPORT_SYMBOL_GPL(blk_mq_poll
);
2933 void blk_mq_disable_hotplug(void)
2935 mutex_lock(&all_q_mutex
);
2938 void blk_mq_enable_hotplug(void)
2940 mutex_unlock(&all_q_mutex
);
2943 static int __init
blk_mq_init(void)
2945 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
2946 blk_mq_hctx_notify_dead
);
2948 cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE
, "block/mq:prepare",
2949 blk_mq_queue_reinit_prepare
,
2950 blk_mq_queue_reinit_dead
);
2953 subsys_initcall(blk_mq_init
);