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 bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
);
41 static void blk_mq_poll_stats_start(struct request_queue
*q
);
42 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
);
44 static int blk_mq_poll_stats_bkt(const struct request
*rq
)
46 int ddir
, bytes
, bucket
;
48 ddir
= rq_data_dir(rq
);
49 bytes
= blk_rq_bytes(rq
);
51 bucket
= ddir
+ 2*(ilog2(bytes
) - 9);
55 else if (bucket
>= BLK_MQ_POLL_STATS_BKTS
)
56 return ddir
+ BLK_MQ_POLL_STATS_BKTS
- 2;
62 * Check if any of the ctx's have pending work in this hardware queue
64 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
66 return !list_empty_careful(&hctx
->dispatch
) ||
67 sbitmap_any_bit_set(&hctx
->ctx_map
) ||
68 blk_mq_sched_has_work(hctx
);
72 * Mark this ctx as having pending work in this hardware queue
74 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
75 struct blk_mq_ctx
*ctx
)
77 if (!sbitmap_test_bit(&hctx
->ctx_map
, ctx
->index_hw
))
78 sbitmap_set_bit(&hctx
->ctx_map
, ctx
->index_hw
);
81 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
82 struct blk_mq_ctx
*ctx
)
84 sbitmap_clear_bit(&hctx
->ctx_map
, ctx
->index_hw
);
88 struct hd_struct
*part
;
89 unsigned int *inflight
;
92 static void blk_mq_check_inflight(struct blk_mq_hw_ctx
*hctx
,
93 struct request
*rq
, void *priv
,
96 struct mq_inflight
*mi
= priv
;
98 if (blk_mq_rq_state(rq
) == MQ_RQ_IN_FLIGHT
) {
100 * index[0] counts the specific partition that was asked
101 * for. index[1] counts the ones that are active on the
102 * whole device, so increment that if mi->part is indeed
103 * a partition, and not a whole device.
105 if (rq
->part
== mi
->part
)
107 if (mi
->part
->partno
)
112 void blk_mq_in_flight(struct request_queue
*q
, struct hd_struct
*part
,
113 unsigned int inflight
[2])
115 struct mq_inflight mi
= { .part
= part
, .inflight
= inflight
, };
117 inflight
[0] = inflight
[1] = 0;
118 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight
, &mi
);
121 void blk_freeze_queue_start(struct request_queue
*q
)
125 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
126 if (freeze_depth
== 1) {
127 percpu_ref_kill(&q
->q_usage_counter
);
129 blk_mq_run_hw_queues(q
, false);
132 EXPORT_SYMBOL_GPL(blk_freeze_queue_start
);
134 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
136 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
138 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
140 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
141 unsigned long timeout
)
143 return wait_event_timeout(q
->mq_freeze_wq
,
144 percpu_ref_is_zero(&q
->q_usage_counter
),
147 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
150 * Guarantee no request is in use, so we can change any data structure of
151 * the queue afterward.
153 void blk_freeze_queue(struct request_queue
*q
)
156 * In the !blk_mq case we are only calling this to kill the
157 * q_usage_counter, otherwise this increases the freeze depth
158 * and waits for it to return to zero. For this reason there is
159 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
160 * exported to drivers as the only user for unfreeze is blk_mq.
162 blk_freeze_queue_start(q
);
165 blk_mq_freeze_queue_wait(q
);
168 void blk_mq_freeze_queue(struct request_queue
*q
)
171 * ...just an alias to keep freeze and unfreeze actions balanced
172 * in the blk_mq_* namespace
176 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
178 void blk_mq_unfreeze_queue(struct request_queue
*q
)
182 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
183 WARN_ON_ONCE(freeze_depth
< 0);
185 percpu_ref_reinit(&q
->q_usage_counter
);
186 wake_up_all(&q
->mq_freeze_wq
);
189 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
192 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
193 * mpt3sas driver such that this function can be removed.
195 void blk_mq_quiesce_queue_nowait(struct request_queue
*q
)
197 blk_queue_flag_set(QUEUE_FLAG_QUIESCED
, q
);
199 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait
);
202 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
205 * Note: this function does not prevent that the struct request end_io()
206 * callback function is invoked. Once this function is returned, we make
207 * sure no dispatch can happen until the queue is unquiesced via
208 * blk_mq_unquiesce_queue().
210 void blk_mq_quiesce_queue(struct request_queue
*q
)
212 struct blk_mq_hw_ctx
*hctx
;
216 blk_mq_quiesce_queue_nowait(q
);
218 queue_for_each_hw_ctx(q
, hctx
, i
) {
219 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
220 synchronize_srcu(hctx
->srcu
);
227 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
230 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
233 * This function recovers queue into the state before quiescing
234 * which is done by blk_mq_quiesce_queue.
236 void blk_mq_unquiesce_queue(struct request_queue
*q
)
238 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
240 /* dispatch requests which are inserted during quiescing */
241 blk_mq_run_hw_queues(q
, true);
243 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
245 void blk_mq_wake_waiters(struct request_queue
*q
)
247 struct blk_mq_hw_ctx
*hctx
;
250 queue_for_each_hw_ctx(q
, hctx
, i
)
251 if (blk_mq_hw_queue_mapped(hctx
))
252 blk_mq_tag_wakeup_all(hctx
->tags
, true);
255 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
257 return blk_mq_has_free_tags(hctx
->tags
);
259 EXPORT_SYMBOL(blk_mq_can_queue
);
261 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
262 unsigned int tag
, unsigned int op
)
264 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
265 struct request
*rq
= tags
->static_rqs
[tag
];
266 req_flags_t rq_flags
= 0;
268 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
270 rq
->internal_tag
= tag
;
272 if (blk_mq_tag_busy(data
->hctx
)) {
273 rq_flags
= RQF_MQ_INFLIGHT
;
274 atomic_inc(&data
->hctx
->nr_active
);
277 rq
->internal_tag
= -1;
278 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
281 /* csd/requeue_work/fifo_time is initialized before use */
283 rq
->mq_ctx
= data
->ctx
;
284 rq
->rq_flags
= rq_flags
;
287 if (data
->flags
& BLK_MQ_REQ_PREEMPT
)
288 rq
->rq_flags
|= RQF_PREEMPT
;
289 if (blk_queue_io_stat(data
->q
))
290 rq
->rq_flags
|= RQF_IO_STAT
;
291 INIT_LIST_HEAD(&rq
->queuelist
);
292 INIT_HLIST_NODE(&rq
->hash
);
293 RB_CLEAR_NODE(&rq
->rb_node
);
296 rq
->start_time
= jiffies
;
297 rq
->nr_phys_segments
= 0;
298 #if defined(CONFIG_BLK_DEV_INTEGRITY)
299 rq
->nr_integrity_segments
= 0;
302 /* tag was already set */
306 INIT_LIST_HEAD(&rq
->timeout_list
);
310 rq
->end_io_data
= NULL
;
313 #ifdef CONFIG_BLK_CGROUP
315 set_start_time_ns(rq
);
316 rq
->io_start_time_ns
= 0;
319 data
->ctx
->rq_dispatched
[op_is_sync(op
)]++;
323 static struct request
*blk_mq_get_request(struct request_queue
*q
,
324 struct bio
*bio
, unsigned int op
,
325 struct blk_mq_alloc_data
*data
)
327 struct elevator_queue
*e
= q
->elevator
;
330 bool put_ctx_on_error
= false;
332 blk_queue_enter_live(q
);
334 if (likely(!data
->ctx
)) {
335 data
->ctx
= blk_mq_get_ctx(q
);
336 put_ctx_on_error
= true;
338 if (likely(!data
->hctx
))
339 data
->hctx
= blk_mq_map_queue(q
, data
->ctx
->cpu
);
341 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
344 data
->flags
|= BLK_MQ_REQ_INTERNAL
;
347 * Flush requests are special and go directly to the
350 if (!op_is_flush(op
) && e
->type
->ops
.mq
.limit_depth
)
351 e
->type
->ops
.mq
.limit_depth(op
, data
);
354 tag
= blk_mq_get_tag(data
);
355 if (tag
== BLK_MQ_TAG_FAIL
) {
356 if (put_ctx_on_error
) {
357 blk_mq_put_ctx(data
->ctx
);
364 rq
= blk_mq_rq_ctx_init(data
, tag
, op
);
365 if (!op_is_flush(op
)) {
367 if (e
&& e
->type
->ops
.mq
.prepare_request
) {
368 if (e
->type
->icq_cache
&& rq_ioc(bio
))
369 blk_mq_sched_assign_ioc(rq
, bio
);
371 e
->type
->ops
.mq
.prepare_request(rq
, bio
);
372 rq
->rq_flags
|= RQF_ELVPRIV
;
375 data
->hctx
->queued
++;
379 struct request
*blk_mq_alloc_request(struct request_queue
*q
, unsigned int op
,
380 blk_mq_req_flags_t flags
)
382 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
386 ret
= blk_queue_enter(q
, flags
);
390 rq
= blk_mq_get_request(q
, NULL
, op
, &alloc_data
);
394 return ERR_PTR(-EWOULDBLOCK
);
396 blk_mq_put_ctx(alloc_data
.ctx
);
399 rq
->__sector
= (sector_t
) -1;
400 rq
->bio
= rq
->biotail
= NULL
;
403 EXPORT_SYMBOL(blk_mq_alloc_request
);
405 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
,
406 unsigned int op
, blk_mq_req_flags_t flags
, unsigned int hctx_idx
)
408 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
};
414 * If the tag allocator sleeps we could get an allocation for a
415 * different hardware context. No need to complicate the low level
416 * allocator for this for the rare use case of a command tied to
419 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
420 return ERR_PTR(-EINVAL
);
422 if (hctx_idx
>= q
->nr_hw_queues
)
423 return ERR_PTR(-EIO
);
425 ret
= blk_queue_enter(q
, flags
);
430 * Check if the hardware context is actually mapped to anything.
431 * If not tell the caller that it should skip this queue.
433 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
434 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
436 return ERR_PTR(-EXDEV
);
438 cpu
= cpumask_first_and(alloc_data
.hctx
->cpumask
, cpu_online_mask
);
439 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
441 rq
= blk_mq_get_request(q
, NULL
, op
, &alloc_data
);
445 return ERR_PTR(-EWOULDBLOCK
);
449 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
451 void blk_mq_free_request(struct request
*rq
)
453 struct request_queue
*q
= rq
->q
;
454 struct elevator_queue
*e
= q
->elevator
;
455 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
456 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(q
, ctx
->cpu
);
457 const int sched_tag
= rq
->internal_tag
;
459 if (rq
->rq_flags
& RQF_ELVPRIV
) {
460 if (e
&& e
->type
->ops
.mq
.finish_request
)
461 e
->type
->ops
.mq
.finish_request(rq
);
463 put_io_context(rq
->elv
.icq
->ioc
);
468 ctx
->rq_completed
[rq_is_sync(rq
)]++;
469 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
470 atomic_dec(&hctx
->nr_active
);
472 if (unlikely(laptop_mode
&& !blk_rq_is_passthrough(rq
)))
473 laptop_io_completion(q
->backing_dev_info
);
475 wbt_done(q
->rq_wb
, &rq
->issue_stat
);
478 blk_put_rl(blk_rq_rl(rq
));
480 blk_mq_rq_update_state(rq
, MQ_RQ_IDLE
);
482 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
484 blk_mq_put_tag(hctx
, hctx
->sched_tags
, ctx
, sched_tag
);
485 blk_mq_sched_restart(hctx
);
488 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
490 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
492 blk_account_io_done(rq
);
495 wbt_done(rq
->q
->rq_wb
, &rq
->issue_stat
);
496 rq
->end_io(rq
, error
);
498 if (unlikely(blk_bidi_rq(rq
)))
499 blk_mq_free_request(rq
->next_rq
);
500 blk_mq_free_request(rq
);
503 EXPORT_SYMBOL(__blk_mq_end_request
);
505 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
507 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
509 __blk_mq_end_request(rq
, error
);
511 EXPORT_SYMBOL(blk_mq_end_request
);
513 static void __blk_mq_complete_request_remote(void *data
)
515 struct request
*rq
= data
;
517 rq
->q
->softirq_done_fn(rq
);
520 static void __blk_mq_complete_request(struct request
*rq
)
522 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
526 WARN_ON_ONCE(blk_mq_rq_state(rq
) != MQ_RQ_IN_FLIGHT
);
527 blk_mq_rq_update_state(rq
, MQ_RQ_COMPLETE
);
529 if (rq
->internal_tag
!= -1)
530 blk_mq_sched_completed_request(rq
);
531 if (rq
->rq_flags
& RQF_STATS
) {
532 blk_mq_poll_stats_start(rq
->q
);
536 if (!test_bit(QUEUE_FLAG_SAME_COMP
, &rq
->q
->queue_flags
)) {
537 rq
->q
->softirq_done_fn(rq
);
542 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &rq
->q
->queue_flags
))
543 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
545 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
546 rq
->csd
.func
= __blk_mq_complete_request_remote
;
549 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
551 rq
->q
->softirq_done_fn(rq
);
556 static void hctx_unlock(struct blk_mq_hw_ctx
*hctx
, int srcu_idx
)
557 __releases(hctx
->srcu
)
559 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
))
562 srcu_read_unlock(hctx
->srcu
, srcu_idx
);
565 static void hctx_lock(struct blk_mq_hw_ctx
*hctx
, int *srcu_idx
)
566 __acquires(hctx
->srcu
)
568 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
569 /* shut up gcc false positive */
573 *srcu_idx
= srcu_read_lock(hctx
->srcu
);
576 static void blk_mq_rq_update_aborted_gstate(struct request
*rq
, u64 gstate
)
581 * blk_mq_rq_aborted_gstate() is used from the completion path and
582 * can thus be called from irq context. u64_stats_fetch in the
583 * middle of update on the same CPU leads to lockup. Disable irq
586 local_irq_save(flags
);
587 u64_stats_update_begin(&rq
->aborted_gstate_sync
);
588 rq
->aborted_gstate
= gstate
;
589 u64_stats_update_end(&rq
->aborted_gstate_sync
);
590 local_irq_restore(flags
);
593 static u64
blk_mq_rq_aborted_gstate(struct request
*rq
)
599 start
= u64_stats_fetch_begin(&rq
->aborted_gstate_sync
);
600 aborted_gstate
= rq
->aborted_gstate
;
601 } while (u64_stats_fetch_retry(&rq
->aborted_gstate_sync
, start
));
603 return aborted_gstate
;
607 * blk_mq_complete_request - end I/O on a request
608 * @rq: the request being processed
611 * Ends all I/O on a request. It does not handle partial completions.
612 * The actual completion happens out-of-order, through a IPI handler.
614 void blk_mq_complete_request(struct request
*rq
)
616 struct request_queue
*q
= rq
->q
;
617 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(q
, rq
->mq_ctx
->cpu
);
620 if (unlikely(blk_should_fake_timeout(q
)))
624 * If @rq->aborted_gstate equals the current instance, timeout is
625 * claiming @rq and we lost. This is synchronized through
626 * hctx_lock(). See blk_mq_timeout_work() for details.
628 * Completion path never blocks and we can directly use RCU here
629 * instead of hctx_lock() which can be either RCU or SRCU.
630 * However, that would complicate paths which want to synchronize
631 * against us. Let stay in sync with the issue path so that
632 * hctx_lock() covers both issue and completion paths.
634 hctx_lock(hctx
, &srcu_idx
);
635 if (blk_mq_rq_aborted_gstate(rq
) != rq
->gstate
)
636 __blk_mq_complete_request(rq
);
637 hctx_unlock(hctx
, srcu_idx
);
639 EXPORT_SYMBOL(blk_mq_complete_request
);
641 int blk_mq_request_started(struct request
*rq
)
643 return blk_mq_rq_state(rq
) != MQ_RQ_IDLE
;
645 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
647 void blk_mq_start_request(struct request
*rq
)
649 struct request_queue
*q
= rq
->q
;
651 blk_mq_sched_started_request(rq
);
653 trace_block_rq_issue(q
, rq
);
655 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
656 blk_stat_set_issue(&rq
->issue_stat
, blk_rq_sectors(rq
));
657 rq
->rq_flags
|= RQF_STATS
;
658 wbt_issue(q
->rq_wb
, &rq
->issue_stat
);
661 WARN_ON_ONCE(blk_mq_rq_state(rq
) != MQ_RQ_IDLE
);
664 * Mark @rq in-flight which also advances the generation number,
665 * and register for timeout. Protect with a seqcount to allow the
666 * timeout path to read both @rq->gstate and @rq->deadline
669 * This is the only place where a request is marked in-flight. If
670 * the timeout path reads an in-flight @rq->gstate, the
671 * @rq->deadline it reads together under @rq->gstate_seq is
672 * guaranteed to be the matching one.
675 write_seqcount_begin(&rq
->gstate_seq
);
677 blk_mq_rq_update_state(rq
, MQ_RQ_IN_FLIGHT
);
680 write_seqcount_end(&rq
->gstate_seq
);
683 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
685 * Make sure space for the drain appears. We know we can do
686 * this because max_hw_segments has been adjusted to be one
687 * fewer than the device can handle.
689 rq
->nr_phys_segments
++;
692 EXPORT_SYMBOL(blk_mq_start_request
);
695 * When we reach here because queue is busy, it's safe to change the state
696 * to IDLE without checking @rq->aborted_gstate because we should still be
697 * holding the RCU read lock and thus protected against timeout.
699 static void __blk_mq_requeue_request(struct request
*rq
)
701 struct request_queue
*q
= rq
->q
;
703 blk_mq_put_driver_tag(rq
);
705 trace_block_rq_requeue(q
, rq
);
706 wbt_requeue(q
->rq_wb
, &rq
->issue_stat
);
708 if (blk_mq_rq_state(rq
) != MQ_RQ_IDLE
) {
709 blk_mq_rq_update_state(rq
, MQ_RQ_IDLE
);
710 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
711 rq
->nr_phys_segments
--;
715 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
717 __blk_mq_requeue_request(rq
);
719 /* this request will be re-inserted to io scheduler queue */
720 blk_mq_sched_requeue_request(rq
);
722 BUG_ON(blk_queued_rq(rq
));
723 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
725 EXPORT_SYMBOL(blk_mq_requeue_request
);
727 static void blk_mq_requeue_work(struct work_struct
*work
)
729 struct request_queue
*q
=
730 container_of(work
, struct request_queue
, requeue_work
.work
);
732 struct request
*rq
, *next
;
734 spin_lock_irq(&q
->requeue_lock
);
735 list_splice_init(&q
->requeue_list
, &rq_list
);
736 spin_unlock_irq(&q
->requeue_lock
);
738 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
739 if (!(rq
->rq_flags
& RQF_SOFTBARRIER
))
742 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
743 list_del_init(&rq
->queuelist
);
744 blk_mq_sched_insert_request(rq
, true, false, false);
747 while (!list_empty(&rq_list
)) {
748 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
749 list_del_init(&rq
->queuelist
);
750 blk_mq_sched_insert_request(rq
, false, false, false);
753 blk_mq_run_hw_queues(q
, false);
756 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
757 bool kick_requeue_list
)
759 struct request_queue
*q
= rq
->q
;
763 * We abuse this flag that is otherwise used by the I/O scheduler to
764 * request head insertion from the workqueue.
766 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
768 spin_lock_irqsave(&q
->requeue_lock
, flags
);
770 rq
->rq_flags
|= RQF_SOFTBARRIER
;
771 list_add(&rq
->queuelist
, &q
->requeue_list
);
773 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
775 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
777 if (kick_requeue_list
)
778 blk_mq_kick_requeue_list(q
);
780 EXPORT_SYMBOL(blk_mq_add_to_requeue_list
);
782 void blk_mq_kick_requeue_list(struct request_queue
*q
)
784 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
, 0);
786 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
788 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
791 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
,
792 msecs_to_jiffies(msecs
));
794 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
796 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
798 if (tag
< tags
->nr_tags
) {
799 prefetch(tags
->rqs
[tag
]);
800 return tags
->rqs
[tag
];
805 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
807 struct blk_mq_timeout_data
{
809 unsigned int next_set
;
810 unsigned int nr_expired
;
813 static void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
815 const struct blk_mq_ops
*ops
= req
->q
->mq_ops
;
816 enum blk_eh_timer_return ret
= BLK_EH_RESET_TIMER
;
818 req
->rq_flags
|= RQF_MQ_TIMEOUT_EXPIRED
;
821 ret
= ops
->timeout(req
, reserved
);
825 __blk_mq_complete_request(req
);
827 case BLK_EH_RESET_TIMER
:
829 * As nothing prevents from completion happening while
830 * ->aborted_gstate is set, this may lead to ignored
831 * completions and further spurious timeouts.
833 blk_mq_rq_update_aborted_gstate(req
, 0);
836 case BLK_EH_NOT_HANDLED
:
839 printk(KERN_ERR
"block: bad eh return: %d\n", ret
);
844 static void blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
845 struct request
*rq
, void *priv
, bool reserved
)
847 struct blk_mq_timeout_data
*data
= priv
;
848 unsigned long gstate
, deadline
;
853 if (rq
->rq_flags
& RQF_MQ_TIMEOUT_EXPIRED
)
856 /* read coherent snapshots of @rq->state_gen and @rq->deadline */
858 start
= read_seqcount_begin(&rq
->gstate_seq
);
859 gstate
= READ_ONCE(rq
->gstate
);
860 deadline
= blk_rq_deadline(rq
);
861 if (!read_seqcount_retry(&rq
->gstate_seq
, start
))
866 /* if in-flight && overdue, mark for abortion */
867 if ((gstate
& MQ_RQ_STATE_MASK
) == MQ_RQ_IN_FLIGHT
&&
868 time_after_eq(jiffies
, deadline
)) {
869 blk_mq_rq_update_aborted_gstate(rq
, gstate
);
872 } else if (!data
->next_set
|| time_after(data
->next
, deadline
)) {
873 data
->next
= deadline
;
878 static void blk_mq_terminate_expired(struct blk_mq_hw_ctx
*hctx
,
879 struct request
*rq
, void *priv
, bool reserved
)
882 * We marked @rq->aborted_gstate and waited for RCU. If there were
883 * completions that we lost to, they would have finished and
884 * updated @rq->gstate by now; otherwise, the completion path is
885 * now guaranteed to see @rq->aborted_gstate and yield. If
886 * @rq->aborted_gstate still matches @rq->gstate, @rq is ours.
888 if (!(rq
->rq_flags
& RQF_MQ_TIMEOUT_EXPIRED
) &&
889 READ_ONCE(rq
->gstate
) == rq
->aborted_gstate
)
890 blk_mq_rq_timed_out(rq
, reserved
);
893 static void blk_mq_timeout_work(struct work_struct
*work
)
895 struct request_queue
*q
=
896 container_of(work
, struct request_queue
, timeout_work
);
897 struct blk_mq_timeout_data data
= {
902 struct blk_mq_hw_ctx
*hctx
;
905 /* A deadlock might occur if a request is stuck requiring a
906 * timeout at the same time a queue freeze is waiting
907 * completion, since the timeout code would not be able to
908 * acquire the queue reference here.
910 * That's why we don't use blk_queue_enter here; instead, we use
911 * percpu_ref_tryget directly, because we need to be able to
912 * obtain a reference even in the short window between the queue
913 * starting to freeze, by dropping the first reference in
914 * blk_freeze_queue_start, and the moment the last request is
915 * consumed, marked by the instant q_usage_counter reaches
918 if (!percpu_ref_tryget(&q
->q_usage_counter
))
921 /* scan for the expired ones and set their ->aborted_gstate */
922 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &data
);
924 if (data
.nr_expired
) {
925 bool has_rcu
= false;
928 * Wait till everyone sees ->aborted_gstate. The
929 * sequential waits for SRCUs aren't ideal. If this ever
930 * becomes a problem, we can add per-hw_ctx rcu_head and
933 queue_for_each_hw_ctx(q
, hctx
, i
) {
934 if (!hctx
->nr_expired
)
937 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
))
940 synchronize_srcu(hctx
->srcu
);
942 hctx
->nr_expired
= 0;
947 /* terminate the ones we won */
948 blk_mq_queue_tag_busy_iter(q
, blk_mq_terminate_expired
, NULL
);
952 data
.next
= blk_rq_timeout(round_jiffies_up(data
.next
));
953 mod_timer(&q
->timeout
, data
.next
);
956 * Request timeouts are handled as a forward rolling timer. If
957 * we end up here it means that no requests are pending and
958 * also that no request has been pending for a while. Mark
961 queue_for_each_hw_ctx(q
, hctx
, i
) {
962 /* the hctx may be unmapped, so check it here */
963 if (blk_mq_hw_queue_mapped(hctx
))
964 blk_mq_tag_idle(hctx
);
970 struct flush_busy_ctx_data
{
971 struct blk_mq_hw_ctx
*hctx
;
972 struct list_head
*list
;
975 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
977 struct flush_busy_ctx_data
*flush_data
= data
;
978 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
979 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
981 spin_lock(&ctx
->lock
);
982 list_splice_tail_init(&ctx
->rq_list
, flush_data
->list
);
983 sbitmap_clear_bit(sb
, bitnr
);
984 spin_unlock(&ctx
->lock
);
989 * Process software queues that have been marked busy, splicing them
990 * to the for-dispatch
992 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
994 struct flush_busy_ctx_data data
= {
999 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
1001 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
1003 struct dispatch_rq_data
{
1004 struct blk_mq_hw_ctx
*hctx
;
1008 static bool dispatch_rq_from_ctx(struct sbitmap
*sb
, unsigned int bitnr
,
1011 struct dispatch_rq_data
*dispatch_data
= data
;
1012 struct blk_mq_hw_ctx
*hctx
= dispatch_data
->hctx
;
1013 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
1015 spin_lock(&ctx
->lock
);
1016 if (unlikely(!list_empty(&ctx
->rq_list
))) {
1017 dispatch_data
->rq
= list_entry_rq(ctx
->rq_list
.next
);
1018 list_del_init(&dispatch_data
->rq
->queuelist
);
1019 if (list_empty(&ctx
->rq_list
))
1020 sbitmap_clear_bit(sb
, bitnr
);
1022 spin_unlock(&ctx
->lock
);
1024 return !dispatch_data
->rq
;
1027 struct request
*blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx
*hctx
,
1028 struct blk_mq_ctx
*start
)
1030 unsigned off
= start
? start
->index_hw
: 0;
1031 struct dispatch_rq_data data
= {
1036 __sbitmap_for_each_set(&hctx
->ctx_map
, off
,
1037 dispatch_rq_from_ctx
, &data
);
1042 static inline unsigned int queued_to_index(unsigned int queued
)
1047 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
1050 bool blk_mq_get_driver_tag(struct request
*rq
, struct blk_mq_hw_ctx
**hctx
,
1053 struct blk_mq_alloc_data data
= {
1055 .hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
),
1056 .flags
= wait
? 0 : BLK_MQ_REQ_NOWAIT
,
1059 might_sleep_if(wait
);
1064 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
1065 data
.flags
|= BLK_MQ_REQ_RESERVED
;
1067 rq
->tag
= blk_mq_get_tag(&data
);
1069 if (blk_mq_tag_busy(data
.hctx
)) {
1070 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
1071 atomic_inc(&data
.hctx
->nr_active
);
1073 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
1079 return rq
->tag
!= -1;
1082 static int blk_mq_dispatch_wake(wait_queue_entry_t
*wait
, unsigned mode
,
1083 int flags
, void *key
)
1085 struct blk_mq_hw_ctx
*hctx
;
1087 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
1089 list_del_init(&wait
->entry
);
1090 blk_mq_run_hw_queue(hctx
, true);
1095 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1096 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1097 * restart. For both cases, take care to check the condition again after
1098 * marking us as waiting.
1100 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx
**hctx
,
1103 struct blk_mq_hw_ctx
*this_hctx
= *hctx
;
1104 struct sbq_wait_state
*ws
;
1105 wait_queue_entry_t
*wait
;
1108 if (!(this_hctx
->flags
& BLK_MQ_F_TAG_SHARED
)) {
1109 if (!test_bit(BLK_MQ_S_SCHED_RESTART
, &this_hctx
->state
))
1110 set_bit(BLK_MQ_S_SCHED_RESTART
, &this_hctx
->state
);
1113 * It's possible that a tag was freed in the window between the
1114 * allocation failure and adding the hardware queue to the wait
1117 * Don't clear RESTART here, someone else could have set it.
1118 * At most this will cost an extra queue run.
1120 return blk_mq_get_driver_tag(rq
, hctx
, false);
1123 wait
= &this_hctx
->dispatch_wait
;
1124 if (!list_empty_careful(&wait
->entry
))
1127 spin_lock(&this_hctx
->lock
);
1128 if (!list_empty(&wait
->entry
)) {
1129 spin_unlock(&this_hctx
->lock
);
1133 ws
= bt_wait_ptr(&this_hctx
->tags
->bitmap_tags
, this_hctx
);
1134 add_wait_queue(&ws
->wait
, wait
);
1137 * It's possible that a tag was freed in the window between the
1138 * allocation failure and adding the hardware queue to the wait
1141 ret
= blk_mq_get_driver_tag(rq
, hctx
, false);
1143 spin_unlock(&this_hctx
->lock
);
1148 * We got a tag, remove ourselves from the wait queue to ensure
1149 * someone else gets the wakeup.
1151 spin_lock_irq(&ws
->wait
.lock
);
1152 list_del_init(&wait
->entry
);
1153 spin_unlock_irq(&ws
->wait
.lock
);
1154 spin_unlock(&this_hctx
->lock
);
1159 #define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1161 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
,
1164 struct blk_mq_hw_ctx
*hctx
;
1165 struct request
*rq
, *nxt
;
1166 bool no_tag
= false;
1168 blk_status_t ret
= BLK_STS_OK
;
1170 if (list_empty(list
))
1173 WARN_ON(!list_is_singular(list
) && got_budget
);
1176 * Now process all the entries, sending them to the driver.
1178 errors
= queued
= 0;
1180 struct blk_mq_queue_data bd
;
1182 rq
= list_first_entry(list
, struct request
, queuelist
);
1184 hctx
= blk_mq_map_queue(rq
->q
, rq
->mq_ctx
->cpu
);
1185 if (!got_budget
&& !blk_mq_get_dispatch_budget(hctx
))
1188 if (!blk_mq_get_driver_tag(rq
, NULL
, false)) {
1190 * The initial allocation attempt failed, so we need to
1191 * rerun the hardware queue when a tag is freed. The
1192 * waitqueue takes care of that. If the queue is run
1193 * before we add this entry back on the dispatch list,
1194 * we'll re-run it below.
1196 if (!blk_mq_mark_tag_wait(&hctx
, rq
)) {
1197 blk_mq_put_dispatch_budget(hctx
);
1199 * For non-shared tags, the RESTART check
1202 if (hctx
->flags
& BLK_MQ_F_TAG_SHARED
)
1208 list_del_init(&rq
->queuelist
);
1213 * Flag last if we have no more requests, or if we have more
1214 * but can't assign a driver tag to it.
1216 if (list_empty(list
))
1219 nxt
= list_first_entry(list
, struct request
, queuelist
);
1220 bd
.last
= !blk_mq_get_driver_tag(nxt
, NULL
, false);
1223 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1224 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
) {
1226 * If an I/O scheduler has been configured and we got a
1227 * driver tag for the next request already, free it
1230 if (!list_empty(list
)) {
1231 nxt
= list_first_entry(list
, struct request
, queuelist
);
1232 blk_mq_put_driver_tag(nxt
);
1234 list_add(&rq
->queuelist
, list
);
1235 __blk_mq_requeue_request(rq
);
1239 if (unlikely(ret
!= BLK_STS_OK
)) {
1241 blk_mq_end_request(rq
, BLK_STS_IOERR
);
1246 } while (!list_empty(list
));
1248 hctx
->dispatched
[queued_to_index(queued
)]++;
1251 * Any items that need requeuing? Stuff them into hctx->dispatch,
1252 * that is where we will continue on next queue run.
1254 if (!list_empty(list
)) {
1257 spin_lock(&hctx
->lock
);
1258 list_splice_init(list
, &hctx
->dispatch
);
1259 spin_unlock(&hctx
->lock
);
1262 * If SCHED_RESTART was set by the caller of this function and
1263 * it is no longer set that means that it was cleared by another
1264 * thread and hence that a queue rerun is needed.
1266 * If 'no_tag' is set, that means that we failed getting
1267 * a driver tag with an I/O scheduler attached. If our dispatch
1268 * waitqueue is no longer active, ensure that we run the queue
1269 * AFTER adding our entries back to the list.
1271 * If no I/O scheduler has been configured it is possible that
1272 * the hardware queue got stopped and restarted before requests
1273 * were pushed back onto the dispatch list. Rerun the queue to
1274 * avoid starvation. Notes:
1275 * - blk_mq_run_hw_queue() checks whether or not a queue has
1276 * been stopped before rerunning a queue.
1277 * - Some but not all block drivers stop a queue before
1278 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1281 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1282 * bit is set, run queue after a delay to avoid IO stalls
1283 * that could otherwise occur if the queue is idle.
1285 needs_restart
= blk_mq_sched_needs_restart(hctx
);
1286 if (!needs_restart
||
1287 (no_tag
&& list_empty_careful(&hctx
->dispatch_wait
.entry
)))
1288 blk_mq_run_hw_queue(hctx
, true);
1289 else if (needs_restart
&& (ret
== BLK_STS_RESOURCE
))
1290 blk_mq_delay_run_hw_queue(hctx
, BLK_MQ_RESOURCE_DELAY
);
1293 return (queued
+ errors
) != 0;
1296 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1301 * We should be running this queue from one of the CPUs that
1304 * There are at least two related races now between setting
1305 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1306 * __blk_mq_run_hw_queue():
1308 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1309 * but later it becomes online, then this warning is harmless
1312 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1313 * but later it becomes offline, then the warning can't be
1314 * triggered, and we depend on blk-mq timeout handler to
1315 * handle dispatched requests to this hctx
1317 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1318 cpu_online(hctx
->next_cpu
)) {
1319 printk(KERN_WARNING
"run queue from wrong CPU %d, hctx %s\n",
1320 raw_smp_processor_id(),
1321 cpumask_empty(hctx
->cpumask
) ? "inactive": "active");
1326 * We can't run the queue inline with ints disabled. Ensure that
1327 * we catch bad users of this early.
1329 WARN_ON_ONCE(in_interrupt());
1331 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1333 hctx_lock(hctx
, &srcu_idx
);
1334 blk_mq_sched_dispatch_requests(hctx
);
1335 hctx_unlock(hctx
, srcu_idx
);
1339 * It'd be great if the workqueue API had a way to pass
1340 * in a mask and had some smarts for more clever placement.
1341 * For now we just round-robin here, switching for every
1342 * BLK_MQ_CPU_WORK_BATCH queued items.
1344 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1347 int next_cpu
= hctx
->next_cpu
;
1349 if (hctx
->queue
->nr_hw_queues
== 1)
1350 return WORK_CPU_UNBOUND
;
1352 if (--hctx
->next_cpu_batch
<= 0) {
1354 next_cpu
= cpumask_next_and(next_cpu
, hctx
->cpumask
,
1356 if (next_cpu
>= nr_cpu_ids
)
1357 next_cpu
= cpumask_first_and(hctx
->cpumask
, cpu_online_mask
);
1360 * No online CPU is found, so have to make sure hctx->next_cpu
1361 * is set correctly for not breaking workqueue.
1363 if (next_cpu
>= nr_cpu_ids
)
1364 next_cpu
= cpumask_first(hctx
->cpumask
);
1365 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1369 * Do unbound schedule if we can't find a online CPU for this hctx,
1370 * and it should only happen in the path of handling CPU DEAD.
1372 if (!cpu_online(next_cpu
)) {
1379 * Make sure to re-select CPU next time once after CPUs
1380 * in hctx->cpumask become online again.
1382 hctx
->next_cpu
= next_cpu
;
1383 hctx
->next_cpu_batch
= 1;
1384 return WORK_CPU_UNBOUND
;
1387 hctx
->next_cpu
= next_cpu
;
1391 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1392 unsigned long msecs
)
1394 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx
)))
1397 if (unlikely(blk_mq_hctx_stopped(hctx
)))
1400 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1401 int cpu
= get_cpu();
1402 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1403 __blk_mq_run_hw_queue(hctx
);
1411 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
,
1412 msecs_to_jiffies(msecs
));
1415 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1417 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1419 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1421 bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1427 * When queue is quiesced, we may be switching io scheduler, or
1428 * updating nr_hw_queues, or other things, and we can't run queue
1429 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1431 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1434 hctx_lock(hctx
, &srcu_idx
);
1435 need_run
= !blk_queue_quiesced(hctx
->queue
) &&
1436 blk_mq_hctx_has_pending(hctx
);
1437 hctx_unlock(hctx
, srcu_idx
);
1440 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1446 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1448 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1450 struct blk_mq_hw_ctx
*hctx
;
1453 queue_for_each_hw_ctx(q
, hctx
, i
) {
1454 if (blk_mq_hctx_stopped(hctx
))
1457 blk_mq_run_hw_queue(hctx
, async
);
1460 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1463 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1464 * @q: request queue.
1466 * The caller is responsible for serializing this function against
1467 * blk_mq_{start,stop}_hw_queue().
1469 bool blk_mq_queue_stopped(struct request_queue
*q
)
1471 struct blk_mq_hw_ctx
*hctx
;
1474 queue_for_each_hw_ctx(q
, hctx
, i
)
1475 if (blk_mq_hctx_stopped(hctx
))
1480 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1483 * This function is often used for pausing .queue_rq() by driver when
1484 * there isn't enough resource or some conditions aren't satisfied, and
1485 * BLK_STS_RESOURCE is usually returned.
1487 * We do not guarantee that dispatch can be drained or blocked
1488 * after blk_mq_stop_hw_queue() returns. Please use
1489 * blk_mq_quiesce_queue() for that requirement.
1491 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1493 cancel_delayed_work(&hctx
->run_work
);
1495 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1497 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1500 * This function is often used for pausing .queue_rq() by driver when
1501 * there isn't enough resource or some conditions aren't satisfied, and
1502 * BLK_STS_RESOURCE is usually returned.
1504 * We do not guarantee that dispatch can be drained or blocked
1505 * after blk_mq_stop_hw_queues() returns. Please use
1506 * blk_mq_quiesce_queue() for that requirement.
1508 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1510 struct blk_mq_hw_ctx
*hctx
;
1513 queue_for_each_hw_ctx(q
, hctx
, i
)
1514 blk_mq_stop_hw_queue(hctx
);
1516 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1518 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1520 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1522 blk_mq_run_hw_queue(hctx
, false);
1524 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1526 void blk_mq_start_hw_queues(struct request_queue
*q
)
1528 struct blk_mq_hw_ctx
*hctx
;
1531 queue_for_each_hw_ctx(q
, hctx
, i
)
1532 blk_mq_start_hw_queue(hctx
);
1534 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1536 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1538 if (!blk_mq_hctx_stopped(hctx
))
1541 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1542 blk_mq_run_hw_queue(hctx
, async
);
1544 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1546 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1548 struct blk_mq_hw_ctx
*hctx
;
1551 queue_for_each_hw_ctx(q
, hctx
, i
)
1552 blk_mq_start_stopped_hw_queue(hctx
, async
);
1554 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1556 static void blk_mq_run_work_fn(struct work_struct
*work
)
1558 struct blk_mq_hw_ctx
*hctx
;
1560 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1563 * If we are stopped, don't run the queue. The exception is if
1564 * BLK_MQ_S_START_ON_RUN is set. For that case, we auto-clear
1565 * the STOPPED bit and run it.
1567 if (test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
)) {
1568 if (!test_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
))
1571 clear_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1572 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1575 __blk_mq_run_hw_queue(hctx
);
1579 void blk_mq_delay_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1581 if (WARN_ON_ONCE(!blk_mq_hw_queue_mapped(hctx
)))
1585 * Stop the hw queue, then modify currently delayed work.
1586 * This should prevent us from running the queue prematurely.
1587 * Mark the queue as auto-clearing STOPPED when it runs.
1589 blk_mq_stop_hw_queue(hctx
);
1590 set_bit(BLK_MQ_S_START_ON_RUN
, &hctx
->state
);
1591 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
),
1593 msecs_to_jiffies(msecs
));
1595 EXPORT_SYMBOL(blk_mq_delay_queue
);
1597 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1601 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1603 lockdep_assert_held(&ctx
->lock
);
1605 trace_block_rq_insert(hctx
->queue
, rq
);
1608 list_add(&rq
->queuelist
, &ctx
->rq_list
);
1610 list_add_tail(&rq
->queuelist
, &ctx
->rq_list
);
1613 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1616 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1618 lockdep_assert_held(&ctx
->lock
);
1620 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1621 blk_mq_hctx_mark_pending(hctx
, ctx
);
1625 * Should only be used carefully, when the caller knows we want to
1626 * bypass a potential IO scheduler on the target device.
1628 void blk_mq_request_bypass_insert(struct request
*rq
, bool run_queue
)
1630 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1631 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(rq
->q
, ctx
->cpu
);
1633 spin_lock(&hctx
->lock
);
1634 list_add_tail(&rq
->queuelist
, &hctx
->dispatch
);
1635 spin_unlock(&hctx
->lock
);
1638 blk_mq_run_hw_queue(hctx
, false);
1641 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1642 struct list_head
*list
)
1646 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1649 spin_lock(&ctx
->lock
);
1650 while (!list_empty(list
)) {
1653 rq
= list_first_entry(list
, struct request
, queuelist
);
1654 BUG_ON(rq
->mq_ctx
!= ctx
);
1655 list_del_init(&rq
->queuelist
);
1656 __blk_mq_insert_req_list(hctx
, rq
, false);
1658 blk_mq_hctx_mark_pending(hctx
, ctx
);
1659 spin_unlock(&ctx
->lock
);
1662 static int plug_ctx_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1664 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1665 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1667 return !(rqa
->mq_ctx
< rqb
->mq_ctx
||
1668 (rqa
->mq_ctx
== rqb
->mq_ctx
&&
1669 blk_rq_pos(rqa
) < blk_rq_pos(rqb
)));
1672 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1674 struct blk_mq_ctx
*this_ctx
;
1675 struct request_queue
*this_q
;
1678 LIST_HEAD(ctx_list
);
1681 list_splice_init(&plug
->mq_list
, &list
);
1683 list_sort(NULL
, &list
, plug_ctx_cmp
);
1689 while (!list_empty(&list
)) {
1690 rq
= list_entry_rq(list
.next
);
1691 list_del_init(&rq
->queuelist
);
1693 if (rq
->mq_ctx
!= this_ctx
) {
1695 trace_block_unplug(this_q
, depth
, from_schedule
);
1696 blk_mq_sched_insert_requests(this_q
, this_ctx
,
1701 this_ctx
= rq
->mq_ctx
;
1707 list_add_tail(&rq
->queuelist
, &ctx_list
);
1711 * If 'this_ctx' is set, we know we have entries to complete
1712 * on 'ctx_list'. Do those.
1715 trace_block_unplug(this_q
, depth
, from_schedule
);
1716 blk_mq_sched_insert_requests(this_q
, this_ctx
, &ctx_list
,
1721 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1723 blk_init_request_from_bio(rq
, bio
);
1725 blk_rq_set_rl(rq
, blk_get_rl(rq
->q
, bio
));
1727 blk_account_io_start(rq
, true);
1730 static inline void blk_mq_queue_io(struct blk_mq_hw_ctx
*hctx
,
1731 struct blk_mq_ctx
*ctx
,
1734 spin_lock(&ctx
->lock
);
1735 __blk_mq_insert_request(hctx
, rq
, false);
1736 spin_unlock(&ctx
->lock
);
1739 static blk_qc_t
request_to_qc_t(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
1742 return blk_tag_to_qc_t(rq
->tag
, hctx
->queue_num
, false);
1744 return blk_tag_to_qc_t(rq
->internal_tag
, hctx
->queue_num
, true);
1747 static blk_status_t
__blk_mq_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1751 struct request_queue
*q
= rq
->q
;
1752 struct blk_mq_queue_data bd
= {
1756 blk_qc_t new_cookie
;
1759 new_cookie
= request_to_qc_t(hctx
, rq
);
1762 * For OK queue, we are done. For error, caller may kill it.
1763 * Any other error (busy), just add it to our list as we
1764 * previously would have done.
1766 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1769 *cookie
= new_cookie
;
1771 case BLK_STS_RESOURCE
:
1772 case BLK_STS_DEV_RESOURCE
:
1773 __blk_mq_requeue_request(rq
);
1776 *cookie
= BLK_QC_T_NONE
;
1783 static blk_status_t
__blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1788 struct request_queue
*q
= rq
->q
;
1789 bool run_queue
= true;
1792 * RCU or SRCU read lock is needed before checking quiesced flag.
1794 * When queue is stopped or quiesced, ignore 'bypass_insert' from
1795 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
1796 * and avoid driver to try to dispatch again.
1798 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
1800 bypass_insert
= false;
1804 if (q
->elevator
&& !bypass_insert
)
1807 if (!blk_mq_get_dispatch_budget(hctx
))
1810 if (!blk_mq_get_driver_tag(rq
, NULL
, false)) {
1811 blk_mq_put_dispatch_budget(hctx
);
1815 return __blk_mq_issue_directly(hctx
, rq
, cookie
);
1818 return BLK_STS_RESOURCE
;
1820 blk_mq_sched_insert_request(rq
, false, run_queue
, false);
1824 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1825 struct request
*rq
, blk_qc_t
*cookie
)
1830 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1832 hctx_lock(hctx
, &srcu_idx
);
1834 ret
= __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false);
1835 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
)
1836 blk_mq_sched_insert_request(rq
, false, true, false);
1837 else if (ret
!= BLK_STS_OK
)
1838 blk_mq_end_request(rq
, ret
);
1840 hctx_unlock(hctx
, srcu_idx
);
1843 blk_status_t
blk_mq_request_issue_directly(struct request
*rq
)
1847 blk_qc_t unused_cookie
;
1848 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1849 struct blk_mq_hw_ctx
*hctx
= blk_mq_map_queue(rq
->q
, ctx
->cpu
);
1851 hctx_lock(hctx
, &srcu_idx
);
1852 ret
= __blk_mq_try_issue_directly(hctx
, rq
, &unused_cookie
, true);
1853 hctx_unlock(hctx
, srcu_idx
);
1858 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1860 const int is_sync
= op_is_sync(bio
->bi_opf
);
1861 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1862 struct blk_mq_alloc_data data
= { .flags
= 0 };
1864 unsigned int request_count
= 0;
1865 struct blk_plug
*plug
;
1866 struct request
*same_queue_rq
= NULL
;
1868 unsigned int wb_acct
;
1870 blk_queue_bounce(q
, &bio
);
1872 blk_queue_split(q
, &bio
);
1874 if (!bio_integrity_prep(bio
))
1875 return BLK_QC_T_NONE
;
1877 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1878 blk_attempt_plug_merge(q
, bio
, &request_count
, &same_queue_rq
))
1879 return BLK_QC_T_NONE
;
1881 if (blk_mq_sched_bio_merge(q
, bio
))
1882 return BLK_QC_T_NONE
;
1884 wb_acct
= wbt_wait(q
->rq_wb
, bio
, NULL
);
1886 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1888 rq
= blk_mq_get_request(q
, bio
, bio
->bi_opf
, &data
);
1889 if (unlikely(!rq
)) {
1890 __wbt_done(q
->rq_wb
, wb_acct
);
1891 if (bio
->bi_opf
& REQ_NOWAIT
)
1892 bio_wouldblock_error(bio
);
1893 return BLK_QC_T_NONE
;
1896 wbt_track(&rq
->issue_stat
, wb_acct
);
1898 cookie
= request_to_qc_t(data
.hctx
, rq
);
1900 plug
= current
->plug
;
1901 if (unlikely(is_flush_fua
)) {
1902 blk_mq_put_ctx(data
.ctx
);
1903 blk_mq_bio_to_request(rq
, bio
);
1905 /* bypass scheduler for flush rq */
1906 blk_insert_flush(rq
);
1907 blk_mq_run_hw_queue(data
.hctx
, true);
1908 } else if (plug
&& q
->nr_hw_queues
== 1) {
1909 struct request
*last
= NULL
;
1911 blk_mq_put_ctx(data
.ctx
);
1912 blk_mq_bio_to_request(rq
, bio
);
1915 * @request_count may become stale because of schedule
1916 * out, so check the list again.
1918 if (list_empty(&plug
->mq_list
))
1920 else if (blk_queue_nomerges(q
))
1921 request_count
= blk_plug_queued_count(q
);
1924 trace_block_plug(q
);
1926 last
= list_entry_rq(plug
->mq_list
.prev
);
1928 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1929 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1930 blk_flush_plug_list(plug
, false);
1931 trace_block_plug(q
);
1934 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1935 } else if (plug
&& !blk_queue_nomerges(q
)) {
1936 blk_mq_bio_to_request(rq
, bio
);
1939 * We do limited plugging. If the bio can be merged, do that.
1940 * Otherwise the existing request in the plug list will be
1941 * issued. So the plug list will have one request at most
1942 * The plug list might get flushed before this. If that happens,
1943 * the plug list is empty, and same_queue_rq is invalid.
1945 if (list_empty(&plug
->mq_list
))
1946 same_queue_rq
= NULL
;
1948 list_del_init(&same_queue_rq
->queuelist
);
1949 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1951 blk_mq_put_ctx(data
.ctx
);
1953 if (same_queue_rq
) {
1954 data
.hctx
= blk_mq_map_queue(q
,
1955 same_queue_rq
->mq_ctx
->cpu
);
1956 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
1959 } else if (q
->nr_hw_queues
> 1 && is_sync
) {
1960 blk_mq_put_ctx(data
.ctx
);
1961 blk_mq_bio_to_request(rq
, bio
);
1962 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
1963 } else if (q
->elevator
) {
1964 blk_mq_put_ctx(data
.ctx
);
1965 blk_mq_bio_to_request(rq
, bio
);
1966 blk_mq_sched_insert_request(rq
, false, true, true);
1968 blk_mq_put_ctx(data
.ctx
);
1969 blk_mq_bio_to_request(rq
, bio
);
1970 blk_mq_queue_io(data
.hctx
, data
.ctx
, rq
);
1971 blk_mq_run_hw_queue(data
.hctx
, true);
1977 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
1978 unsigned int hctx_idx
)
1982 if (tags
->rqs
&& set
->ops
->exit_request
) {
1985 for (i
= 0; i
< tags
->nr_tags
; i
++) {
1986 struct request
*rq
= tags
->static_rqs
[i
];
1990 set
->ops
->exit_request(set
, rq
, hctx_idx
);
1991 tags
->static_rqs
[i
] = NULL
;
1995 while (!list_empty(&tags
->page_list
)) {
1996 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
1997 list_del_init(&page
->lru
);
1999 * Remove kmemleak object previously allocated in
2000 * blk_mq_init_rq_map().
2002 kmemleak_free(page_address(page
));
2003 __free_pages(page
, page
->private);
2007 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
2011 kfree(tags
->static_rqs
);
2012 tags
->static_rqs
= NULL
;
2014 blk_mq_free_tags(tags
);
2017 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
2018 unsigned int hctx_idx
,
2019 unsigned int nr_tags
,
2020 unsigned int reserved_tags
)
2022 struct blk_mq_tags
*tags
;
2025 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
2026 if (node
== NUMA_NO_NODE
)
2027 node
= set
->numa_node
;
2029 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
2030 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
2034 tags
->rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
2035 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2038 blk_mq_free_tags(tags
);
2042 tags
->static_rqs
= kzalloc_node(nr_tags
* sizeof(struct request
*),
2043 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2045 if (!tags
->static_rqs
) {
2047 blk_mq_free_tags(tags
);
2054 static size_t order_to_size(unsigned int order
)
2056 return (size_t)PAGE_SIZE
<< order
;
2059 static int blk_mq_init_request(struct blk_mq_tag_set
*set
, struct request
*rq
,
2060 unsigned int hctx_idx
, int node
)
2064 if (set
->ops
->init_request
) {
2065 ret
= set
->ops
->init_request(set
, rq
, hctx_idx
, node
);
2070 seqcount_init(&rq
->gstate_seq
);
2071 u64_stats_init(&rq
->aborted_gstate_sync
);
2075 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2076 unsigned int hctx_idx
, unsigned int depth
)
2078 unsigned int i
, j
, entries_per_page
, max_order
= 4;
2079 size_t rq_size
, left
;
2082 node
= blk_mq_hw_queue_to_node(set
->mq_map
, hctx_idx
);
2083 if (node
== NUMA_NO_NODE
)
2084 node
= set
->numa_node
;
2086 INIT_LIST_HEAD(&tags
->page_list
);
2089 * rq_size is the size of the request plus driver payload, rounded
2090 * to the cacheline size
2092 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
2094 left
= rq_size
* depth
;
2096 for (i
= 0; i
< depth
; ) {
2097 int this_order
= max_order
;
2102 while (this_order
&& left
< order_to_size(this_order
- 1))
2106 page
= alloc_pages_node(node
,
2107 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
2113 if (order_to_size(this_order
) < rq_size
)
2120 page
->private = this_order
;
2121 list_add_tail(&page
->lru
, &tags
->page_list
);
2123 p
= page_address(page
);
2125 * Allow kmemleak to scan these pages as they contain pointers
2126 * to additional allocations like via ops->init_request().
2128 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
2129 entries_per_page
= order_to_size(this_order
) / rq_size
;
2130 to_do
= min(entries_per_page
, depth
- i
);
2131 left
-= to_do
* rq_size
;
2132 for (j
= 0; j
< to_do
; j
++) {
2133 struct request
*rq
= p
;
2135 tags
->static_rqs
[i
] = rq
;
2136 if (blk_mq_init_request(set
, rq
, hctx_idx
, node
)) {
2137 tags
->static_rqs
[i
] = NULL
;
2148 blk_mq_free_rqs(set
, tags
, hctx_idx
);
2153 * 'cpu' is going away. splice any existing rq_list entries from this
2154 * software queue to the hw queue dispatch list, and ensure that it
2157 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
2159 struct blk_mq_hw_ctx
*hctx
;
2160 struct blk_mq_ctx
*ctx
;
2163 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
2164 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
2166 spin_lock(&ctx
->lock
);
2167 if (!list_empty(&ctx
->rq_list
)) {
2168 list_splice_init(&ctx
->rq_list
, &tmp
);
2169 blk_mq_hctx_clear_pending(hctx
, ctx
);
2171 spin_unlock(&ctx
->lock
);
2173 if (list_empty(&tmp
))
2176 spin_lock(&hctx
->lock
);
2177 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
2178 spin_unlock(&hctx
->lock
);
2180 blk_mq_run_hw_queue(hctx
, true);
2184 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
2186 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
2190 /* hctx->ctxs will be freed in queue's release handler */
2191 static void blk_mq_exit_hctx(struct request_queue
*q
,
2192 struct blk_mq_tag_set
*set
,
2193 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
2195 blk_mq_debugfs_unregister_hctx(hctx
);
2197 if (blk_mq_hw_queue_mapped(hctx
))
2198 blk_mq_tag_idle(hctx
);
2200 if (set
->ops
->exit_request
)
2201 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
2203 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
2205 if (set
->ops
->exit_hctx
)
2206 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2208 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2209 cleanup_srcu_struct(hctx
->srcu
);
2211 blk_mq_remove_cpuhp(hctx
);
2212 blk_free_flush_queue(hctx
->fq
);
2213 sbitmap_free(&hctx
->ctx_map
);
2216 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
2217 struct blk_mq_tag_set
*set
, int nr_queue
)
2219 struct blk_mq_hw_ctx
*hctx
;
2222 queue_for_each_hw_ctx(q
, hctx
, i
) {
2225 blk_mq_exit_hctx(q
, set
, hctx
, i
);
2229 static int blk_mq_init_hctx(struct request_queue
*q
,
2230 struct blk_mq_tag_set
*set
,
2231 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
2235 node
= hctx
->numa_node
;
2236 if (node
== NUMA_NO_NODE
)
2237 node
= hctx
->numa_node
= set
->numa_node
;
2239 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
2240 spin_lock_init(&hctx
->lock
);
2241 INIT_LIST_HEAD(&hctx
->dispatch
);
2243 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
2245 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
2247 hctx
->tags
= set
->tags
[hctx_idx
];
2250 * Allocate space for all possible cpus to avoid allocation at
2253 hctx
->ctxs
= kmalloc_array_node(nr_cpu_ids
, sizeof(void *),
2256 goto unregister_cpu_notifier
;
2258 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8), GFP_KERNEL
,
2264 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
2265 INIT_LIST_HEAD(&hctx
->dispatch_wait
.entry
);
2267 if (set
->ops
->init_hctx
&&
2268 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
2271 if (blk_mq_sched_init_hctx(q
, hctx
, hctx_idx
))
2274 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
);
2276 goto sched_exit_hctx
;
2278 if (blk_mq_init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
, node
))
2281 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2282 init_srcu_struct(hctx
->srcu
);
2284 blk_mq_debugfs_register_hctx(q
, hctx
);
2291 blk_mq_sched_exit_hctx(q
, hctx
, hctx_idx
);
2293 if (set
->ops
->exit_hctx
)
2294 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2296 sbitmap_free(&hctx
->ctx_map
);
2299 unregister_cpu_notifier
:
2300 blk_mq_remove_cpuhp(hctx
);
2304 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2305 unsigned int nr_hw_queues
)
2309 for_each_possible_cpu(i
) {
2310 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2311 struct blk_mq_hw_ctx
*hctx
;
2314 spin_lock_init(&__ctx
->lock
);
2315 INIT_LIST_HEAD(&__ctx
->rq_list
);
2319 * Set local node, IFF we have more than one hw queue. If
2320 * not, we remain on the home node of the device
2322 hctx
= blk_mq_map_queue(q
, i
);
2323 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2324 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2328 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2332 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2333 set
->queue_depth
, set
->reserved_tags
);
2334 if (!set
->tags
[hctx_idx
])
2337 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2342 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2343 set
->tags
[hctx_idx
] = NULL
;
2347 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2348 unsigned int hctx_idx
)
2350 if (set
->tags
[hctx_idx
]) {
2351 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2352 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2353 set
->tags
[hctx_idx
] = NULL
;
2357 static void blk_mq_map_swqueue(struct request_queue
*q
)
2359 unsigned int i
, hctx_idx
;
2360 struct blk_mq_hw_ctx
*hctx
;
2361 struct blk_mq_ctx
*ctx
;
2362 struct blk_mq_tag_set
*set
= q
->tag_set
;
2365 * Avoid others reading imcomplete hctx->cpumask through sysfs
2367 mutex_lock(&q
->sysfs_lock
);
2369 queue_for_each_hw_ctx(q
, hctx
, i
) {
2370 cpumask_clear(hctx
->cpumask
);
2375 * Map software to hardware queues.
2377 * If the cpu isn't present, the cpu is mapped to first hctx.
2379 for_each_possible_cpu(i
) {
2380 hctx_idx
= q
->mq_map
[i
];
2381 /* unmapped hw queue can be remapped after CPU topo changed */
2382 if (!set
->tags
[hctx_idx
] &&
2383 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2385 * If tags initialization fail for some hctx,
2386 * that hctx won't be brought online. In this
2387 * case, remap the current ctx to hctx[0] which
2388 * is guaranteed to always have tags allocated
2393 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2394 hctx
= blk_mq_map_queue(q
, i
);
2396 cpumask_set_cpu(i
, hctx
->cpumask
);
2397 ctx
->index_hw
= hctx
->nr_ctx
;
2398 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2401 mutex_unlock(&q
->sysfs_lock
);
2403 queue_for_each_hw_ctx(q
, hctx
, i
) {
2405 * If no software queues are mapped to this hardware queue,
2406 * disable it and free the request entries.
2408 if (!hctx
->nr_ctx
) {
2409 /* Never unmap queue 0. We need it as a
2410 * fallback in case of a new remap fails
2413 if (i
&& set
->tags
[i
])
2414 blk_mq_free_map_and_requests(set
, i
);
2420 hctx
->tags
= set
->tags
[i
];
2421 WARN_ON(!hctx
->tags
);
2424 * Set the map size to the number of mapped software queues.
2425 * This is more accurate and more efficient than looping
2426 * over all possibly mapped software queues.
2428 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2431 * Initialize batch roundrobin counts
2433 hctx
->next_cpu
= cpumask_first_and(hctx
->cpumask
,
2435 if (hctx
->next_cpu
>= nr_cpu_ids
)
2436 hctx
->next_cpu
= cpumask_first(hctx
->cpumask
);
2437 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2442 * Caller needs to ensure that we're either frozen/quiesced, or that
2443 * the queue isn't live yet.
2445 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2447 struct blk_mq_hw_ctx
*hctx
;
2450 queue_for_each_hw_ctx(q
, hctx
, i
) {
2452 if (test_bit(BLK_MQ_S_SCHED_RESTART
, &hctx
->state
))
2453 atomic_inc(&q
->shared_hctx_restart
);
2454 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2456 if (test_bit(BLK_MQ_S_SCHED_RESTART
, &hctx
->state
))
2457 atomic_dec(&q
->shared_hctx_restart
);
2458 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2463 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
,
2466 struct request_queue
*q
;
2468 lockdep_assert_held(&set
->tag_list_lock
);
2470 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2471 blk_mq_freeze_queue(q
);
2472 queue_set_hctx_shared(q
, shared
);
2473 blk_mq_unfreeze_queue(q
);
2477 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2479 struct blk_mq_tag_set
*set
= q
->tag_set
;
2481 mutex_lock(&set
->tag_list_lock
);
2482 list_del_rcu(&q
->tag_set_list
);
2483 INIT_LIST_HEAD(&q
->tag_set_list
);
2484 if (list_is_singular(&set
->tag_list
)) {
2485 /* just transitioned to unshared */
2486 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2487 /* update existing queue */
2488 blk_mq_update_tag_set_depth(set
, false);
2490 mutex_unlock(&set
->tag_list_lock
);
2495 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2496 struct request_queue
*q
)
2500 mutex_lock(&set
->tag_list_lock
);
2503 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2505 if (!list_empty(&set
->tag_list
) &&
2506 !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2507 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2508 /* update existing queue */
2509 blk_mq_update_tag_set_depth(set
, true);
2511 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2512 queue_set_hctx_shared(q
, true);
2513 list_add_tail_rcu(&q
->tag_set_list
, &set
->tag_list
);
2515 mutex_unlock(&set
->tag_list_lock
);
2519 * It is the actual release handler for mq, but we do it from
2520 * request queue's release handler for avoiding use-after-free
2521 * and headache because q->mq_kobj shouldn't have been introduced,
2522 * but we can't group ctx/kctx kobj without it.
2524 void blk_mq_release(struct request_queue
*q
)
2526 struct blk_mq_hw_ctx
*hctx
;
2529 /* hctx kobj stays in hctx */
2530 queue_for_each_hw_ctx(q
, hctx
, i
) {
2533 kobject_put(&hctx
->kobj
);
2538 kfree(q
->queue_hw_ctx
);
2541 * release .mq_kobj and sw queue's kobject now because
2542 * both share lifetime with request queue.
2544 blk_mq_sysfs_deinit(q
);
2546 free_percpu(q
->queue_ctx
);
2549 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2551 struct request_queue
*uninit_q
, *q
;
2553 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
, NULL
);
2555 return ERR_PTR(-ENOMEM
);
2557 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2559 blk_cleanup_queue(uninit_q
);
2563 EXPORT_SYMBOL(blk_mq_init_queue
);
2565 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set
*tag_set
)
2567 int hw_ctx_size
= sizeof(struct blk_mq_hw_ctx
);
2569 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx
, srcu
),
2570 __alignof__(struct blk_mq_hw_ctx
)) !=
2571 sizeof(struct blk_mq_hw_ctx
));
2573 if (tag_set
->flags
& BLK_MQ_F_BLOCKING
)
2574 hw_ctx_size
+= sizeof(struct srcu_struct
);
2579 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2580 struct request_queue
*q
)
2583 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2585 blk_mq_sysfs_unregister(q
);
2587 /* protect against switching io scheduler */
2588 mutex_lock(&q
->sysfs_lock
);
2589 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2595 node
= blk_mq_hw_queue_to_node(q
->mq_map
, i
);
2596 hctxs
[i
] = kzalloc_node(blk_mq_hw_ctx_size(set
),
2601 if (!zalloc_cpumask_var_node(&hctxs
[i
]->cpumask
, GFP_KERNEL
,
2608 atomic_set(&hctxs
[i
]->nr_active
, 0);
2609 hctxs
[i
]->numa_node
= node
;
2610 hctxs
[i
]->queue_num
= i
;
2612 if (blk_mq_init_hctx(q
, set
, hctxs
[i
], i
)) {
2613 free_cpumask_var(hctxs
[i
]->cpumask
);
2618 blk_mq_hctx_kobj_init(hctxs
[i
]);
2620 for (j
= i
; j
< q
->nr_hw_queues
; j
++) {
2621 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2625 blk_mq_free_map_and_requests(set
, j
);
2626 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2627 kobject_put(&hctx
->kobj
);
2632 q
->nr_hw_queues
= i
;
2633 mutex_unlock(&q
->sysfs_lock
);
2634 blk_mq_sysfs_register(q
);
2637 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2638 struct request_queue
*q
)
2640 /* mark the queue as mq asap */
2641 q
->mq_ops
= set
->ops
;
2643 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2644 blk_mq_poll_stats_bkt
,
2645 BLK_MQ_POLL_STATS_BKTS
, q
);
2649 q
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2653 /* init q->mq_kobj and sw queues' kobjects */
2654 blk_mq_sysfs_init(q
);
2656 q
->queue_hw_ctx
= kzalloc_node(nr_cpu_ids
* sizeof(*(q
->queue_hw_ctx
)),
2657 GFP_KERNEL
, set
->numa_node
);
2658 if (!q
->queue_hw_ctx
)
2661 q
->mq_map
= set
->mq_map
;
2663 blk_mq_realloc_hw_ctxs(set
, q
);
2664 if (!q
->nr_hw_queues
)
2667 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2668 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2670 q
->nr_queues
= nr_cpu_ids
;
2672 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2674 if (!(set
->flags
& BLK_MQ_F_SG_MERGE
))
2675 queue_flag_set_unlocked(QUEUE_FLAG_NO_SG_MERGE
, q
);
2677 q
->sg_reserved_size
= INT_MAX
;
2679 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2680 INIT_LIST_HEAD(&q
->requeue_list
);
2681 spin_lock_init(&q
->requeue_lock
);
2683 blk_queue_make_request(q
, blk_mq_make_request
);
2684 if (q
->mq_ops
->poll
)
2685 q
->poll_fn
= blk_mq_poll
;
2688 * Do this after blk_queue_make_request() overrides it...
2690 q
->nr_requests
= set
->queue_depth
;
2693 * Default to classic polling
2697 if (set
->ops
->complete
)
2698 blk_queue_softirq_done(q
, set
->ops
->complete
);
2700 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2701 blk_mq_add_queue_tag_set(set
, q
);
2702 blk_mq_map_swqueue(q
);
2704 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2707 ret
= blk_mq_sched_init(q
);
2709 return ERR_PTR(ret
);
2715 kfree(q
->queue_hw_ctx
);
2717 free_percpu(q
->queue_ctx
);
2720 return ERR_PTR(-ENOMEM
);
2722 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2724 void blk_mq_free_queue(struct request_queue
*q
)
2726 struct blk_mq_tag_set
*set
= q
->tag_set
;
2728 blk_mq_del_queue_tag_set(q
);
2729 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2732 /* Basically redo blk_mq_init_queue with queue frozen */
2733 static void blk_mq_queue_reinit(struct request_queue
*q
)
2735 WARN_ON_ONCE(!atomic_read(&q
->mq_freeze_depth
));
2737 blk_mq_debugfs_unregister_hctxs(q
);
2738 blk_mq_sysfs_unregister(q
);
2741 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
2742 * we should change hctx numa_node according to the new topology (this
2743 * involves freeing and re-allocating memory, worth doing?)
2745 blk_mq_map_swqueue(q
);
2747 blk_mq_sysfs_register(q
);
2748 blk_mq_debugfs_register_hctxs(q
);
2751 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2755 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2756 if (!__blk_mq_alloc_rq_map(set
, i
))
2763 blk_mq_free_rq_map(set
->tags
[i
]);
2769 * Allocate the request maps associated with this tag_set. Note that this
2770 * may reduce the depth asked for, if memory is tight. set->queue_depth
2771 * will be updated to reflect the allocated depth.
2773 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2778 depth
= set
->queue_depth
;
2780 err
= __blk_mq_alloc_rq_maps(set
);
2784 set
->queue_depth
>>= 1;
2785 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2789 } while (set
->queue_depth
);
2791 if (!set
->queue_depth
|| err
) {
2792 pr_err("blk-mq: failed to allocate request map\n");
2796 if (depth
!= set
->queue_depth
)
2797 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2798 depth
, set
->queue_depth
);
2803 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
2805 if (set
->ops
->map_queues
) {
2808 * transport .map_queues is usually done in the following
2811 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
2812 * mask = get_cpu_mask(queue)
2813 * for_each_cpu(cpu, mask)
2814 * set->mq_map[cpu] = queue;
2817 * When we need to remap, the table has to be cleared for
2818 * killing stale mapping since one CPU may not be mapped
2821 for_each_possible_cpu(cpu
)
2822 set
->mq_map
[cpu
] = 0;
2824 return set
->ops
->map_queues(set
);
2826 return blk_mq_map_queues(set
);
2830 * Alloc a tag set to be associated with one or more request queues.
2831 * May fail with EINVAL for various error conditions. May adjust the
2832 * requested depth down, if if it too large. In that case, the set
2833 * value will be stored in set->queue_depth.
2835 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2839 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2841 if (!set
->nr_hw_queues
)
2843 if (!set
->queue_depth
)
2845 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2848 if (!set
->ops
->queue_rq
)
2851 if (!set
->ops
->get_budget
^ !set
->ops
->put_budget
)
2854 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2855 pr_info("blk-mq: reduced tag depth to %u\n",
2857 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
2861 * If a crashdump is active, then we are potentially in a very
2862 * memory constrained environment. Limit us to 1 queue and
2863 * 64 tags to prevent using too much memory.
2865 if (is_kdump_kernel()) {
2866 set
->nr_hw_queues
= 1;
2867 set
->queue_depth
= min(64U, set
->queue_depth
);
2870 * There is no use for more h/w queues than cpus.
2872 if (set
->nr_hw_queues
> nr_cpu_ids
)
2873 set
->nr_hw_queues
= nr_cpu_ids
;
2875 set
->tags
= kzalloc_node(nr_cpu_ids
* sizeof(struct blk_mq_tags
*),
2876 GFP_KERNEL
, set
->numa_node
);
2881 set
->mq_map
= kzalloc_node(sizeof(*set
->mq_map
) * nr_cpu_ids
,
2882 GFP_KERNEL
, set
->numa_node
);
2886 ret
= blk_mq_update_queue_map(set
);
2888 goto out_free_mq_map
;
2890 ret
= blk_mq_alloc_rq_maps(set
);
2892 goto out_free_mq_map
;
2894 mutex_init(&set
->tag_list_lock
);
2895 INIT_LIST_HEAD(&set
->tag_list
);
2907 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
2909 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
2913 for (i
= 0; i
< nr_cpu_ids
; i
++)
2914 blk_mq_free_map_and_requests(set
, i
);
2922 EXPORT_SYMBOL(blk_mq_free_tag_set
);
2924 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
2926 struct blk_mq_tag_set
*set
= q
->tag_set
;
2927 struct blk_mq_hw_ctx
*hctx
;
2933 blk_mq_freeze_queue(q
);
2934 blk_mq_quiesce_queue(q
);
2937 queue_for_each_hw_ctx(q
, hctx
, i
) {
2941 * If we're using an MQ scheduler, just update the scheduler
2942 * queue depth. This is similar to what the old code would do.
2944 if (!hctx
->sched_tags
) {
2945 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
, nr
,
2948 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
2956 q
->nr_requests
= nr
;
2958 blk_mq_unquiesce_queue(q
);
2959 blk_mq_unfreeze_queue(q
);
2964 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
2967 struct request_queue
*q
;
2969 lockdep_assert_held(&set
->tag_list_lock
);
2971 if (nr_hw_queues
> nr_cpu_ids
)
2972 nr_hw_queues
= nr_cpu_ids
;
2973 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
2976 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2977 blk_mq_freeze_queue(q
);
2979 set
->nr_hw_queues
= nr_hw_queues
;
2980 blk_mq_update_queue_map(set
);
2981 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2982 blk_mq_realloc_hw_ctxs(set
, q
);
2983 blk_mq_queue_reinit(q
);
2986 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
2987 blk_mq_unfreeze_queue(q
);
2990 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
2992 mutex_lock(&set
->tag_list_lock
);
2993 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
2994 mutex_unlock(&set
->tag_list_lock
);
2996 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
2998 /* Enable polling stats and return whether they were already enabled. */
2999 static bool blk_poll_stats_enable(struct request_queue
*q
)
3001 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3002 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS
, q
))
3004 blk_stat_add_callback(q
, q
->poll_cb
);
3008 static void blk_mq_poll_stats_start(struct request_queue
*q
)
3011 * We don't arm the callback if polling stats are not enabled or the
3012 * callback is already active.
3014 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3015 blk_stat_is_active(q
->poll_cb
))
3018 blk_stat_activate_msecs(q
->poll_cb
, 100);
3021 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
3023 struct request_queue
*q
= cb
->data
;
3026 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
3027 if (cb
->stat
[bucket
].nr_samples
)
3028 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
3032 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
3033 struct blk_mq_hw_ctx
*hctx
,
3036 unsigned long ret
= 0;
3040 * If stats collection isn't on, don't sleep but turn it on for
3043 if (!blk_poll_stats_enable(q
))
3047 * As an optimistic guess, use half of the mean service time
3048 * for this type of request. We can (and should) make this smarter.
3049 * For instance, if the completion latencies are tight, we can
3050 * get closer than just half the mean. This is especially
3051 * important on devices where the completion latencies are longer
3052 * than ~10 usec. We do use the stats for the relevant IO size
3053 * if available which does lead to better estimates.
3055 bucket
= blk_mq_poll_stats_bkt(rq
);
3059 if (q
->poll_stat
[bucket
].nr_samples
)
3060 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
3065 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
3066 struct blk_mq_hw_ctx
*hctx
,
3069 struct hrtimer_sleeper hs
;
3070 enum hrtimer_mode mode
;
3074 if (rq
->rq_flags
& RQF_MQ_POLL_SLEPT
)
3080 * -1: don't ever hybrid sleep
3081 * 0: use half of prev avg
3082 * >0: use this specific value
3084 if (q
->poll_nsec
== -1)
3086 else if (q
->poll_nsec
> 0)
3087 nsecs
= q
->poll_nsec
;
3089 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
3094 rq
->rq_flags
|= RQF_MQ_POLL_SLEPT
;
3097 * This will be replaced with the stats tracking code, using
3098 * 'avg_completion_time / 2' as the pre-sleep target.
3102 mode
= HRTIMER_MODE_REL
;
3103 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
3104 hrtimer_set_expires(&hs
.timer
, kt
);
3106 hrtimer_init_sleeper(&hs
, current
);
3108 if (blk_mq_rq_state(rq
) == MQ_RQ_COMPLETE
)
3110 set_current_state(TASK_UNINTERRUPTIBLE
);
3111 hrtimer_start_expires(&hs
.timer
, mode
);
3114 hrtimer_cancel(&hs
.timer
);
3115 mode
= HRTIMER_MODE_ABS
;
3116 } while (hs
.task
&& !signal_pending(current
));
3118 __set_current_state(TASK_RUNNING
);
3119 destroy_hrtimer_on_stack(&hs
.timer
);
3123 static bool __blk_mq_poll(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
)
3125 struct request_queue
*q
= hctx
->queue
;
3129 * If we sleep, have the caller restart the poll loop to reset
3130 * the state. Like for the other success return cases, the
3131 * caller is responsible for checking if the IO completed. If
3132 * the IO isn't complete, we'll get called again and will go
3133 * straight to the busy poll loop.
3135 if (blk_mq_poll_hybrid_sleep(q
, hctx
, rq
))
3138 hctx
->poll_considered
++;
3140 state
= current
->state
;
3141 while (!need_resched()) {
3144 hctx
->poll_invoked
++;
3146 ret
= q
->mq_ops
->poll(hctx
, rq
->tag
);
3148 hctx
->poll_success
++;
3149 set_current_state(TASK_RUNNING
);
3153 if (signal_pending_state(state
, current
))
3154 set_current_state(TASK_RUNNING
);
3156 if (current
->state
== TASK_RUNNING
)
3163 __set_current_state(TASK_RUNNING
);
3167 static bool blk_mq_poll(struct request_queue
*q
, blk_qc_t cookie
)
3169 struct blk_mq_hw_ctx
*hctx
;
3172 if (!test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
3175 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
3176 if (!blk_qc_t_is_internal(cookie
))
3177 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
3179 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
3181 * With scheduling, if the request has completed, we'll
3182 * get a NULL return here, as we clear the sched tag when
3183 * that happens. The request still remains valid, like always,
3184 * so we should be safe with just the NULL check.
3190 return __blk_mq_poll(hctx
, rq
);
3193 static int __init
blk_mq_init(void)
3195 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
3196 blk_mq_hctx_notify_dead
);
3199 subsys_initcall(blk_mq_init
);