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"
39 #include "blk-rq-qos.h"
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 const int bit
= ctx
->index_hw
[hctx
->type
];
79 if (!sbitmap_test_bit(&hctx
->ctx_map
, bit
))
80 sbitmap_set_bit(&hctx
->ctx_map
, bit
);
83 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
84 struct blk_mq_ctx
*ctx
)
86 const int bit
= ctx
->index_hw
[hctx
->type
];
88 sbitmap_clear_bit(&hctx
->ctx_map
, bit
);
92 struct hd_struct
*part
;
93 unsigned int *inflight
;
96 static bool blk_mq_check_inflight(struct blk_mq_hw_ctx
*hctx
,
97 struct request
*rq
, void *priv
,
100 struct mq_inflight
*mi
= priv
;
103 * index[0] counts the specific partition that was asked for.
105 if (rq
->part
== mi
->part
)
111 unsigned int blk_mq_in_flight(struct request_queue
*q
, struct hd_struct
*part
)
113 unsigned inflight
[2];
114 struct mq_inflight mi
= { .part
= part
, .inflight
= inflight
, };
116 inflight
[0] = inflight
[1] = 0;
117 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight
, &mi
);
122 static bool blk_mq_check_inflight_rw(struct blk_mq_hw_ctx
*hctx
,
123 struct request
*rq
, void *priv
,
126 struct mq_inflight
*mi
= priv
;
128 if (rq
->part
== mi
->part
)
129 mi
->inflight
[rq_data_dir(rq
)]++;
134 void blk_mq_in_flight_rw(struct request_queue
*q
, struct hd_struct
*part
,
135 unsigned int inflight
[2])
137 struct mq_inflight mi
= { .part
= part
, .inflight
= inflight
, };
139 inflight
[0] = inflight
[1] = 0;
140 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight_rw
, &mi
);
143 void blk_freeze_queue_start(struct request_queue
*q
)
147 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
148 if (freeze_depth
== 1) {
149 percpu_ref_kill(&q
->q_usage_counter
);
151 blk_mq_run_hw_queues(q
, false);
154 EXPORT_SYMBOL_GPL(blk_freeze_queue_start
);
156 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
158 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
160 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
162 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
163 unsigned long timeout
)
165 return wait_event_timeout(q
->mq_freeze_wq
,
166 percpu_ref_is_zero(&q
->q_usage_counter
),
169 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
172 * Guarantee no request is in use, so we can change any data structure of
173 * the queue afterward.
175 void blk_freeze_queue(struct request_queue
*q
)
178 * In the !blk_mq case we are only calling this to kill the
179 * q_usage_counter, otherwise this increases the freeze depth
180 * and waits for it to return to zero. For this reason there is
181 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
182 * exported to drivers as the only user for unfreeze is blk_mq.
184 blk_freeze_queue_start(q
);
185 blk_mq_freeze_queue_wait(q
);
188 void blk_mq_freeze_queue(struct request_queue
*q
)
191 * ...just an alias to keep freeze and unfreeze actions balanced
192 * in the blk_mq_* namespace
196 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
198 void blk_mq_unfreeze_queue(struct request_queue
*q
)
202 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
203 WARN_ON_ONCE(freeze_depth
< 0);
205 percpu_ref_resurrect(&q
->q_usage_counter
);
206 wake_up_all(&q
->mq_freeze_wq
);
209 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
212 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
213 * mpt3sas driver such that this function can be removed.
215 void blk_mq_quiesce_queue_nowait(struct request_queue
*q
)
217 blk_queue_flag_set(QUEUE_FLAG_QUIESCED
, q
);
219 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait
);
222 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
225 * Note: this function does not prevent that the struct request end_io()
226 * callback function is invoked. Once this function is returned, we make
227 * sure no dispatch can happen until the queue is unquiesced via
228 * blk_mq_unquiesce_queue().
230 void blk_mq_quiesce_queue(struct request_queue
*q
)
232 struct blk_mq_hw_ctx
*hctx
;
236 blk_mq_quiesce_queue_nowait(q
);
238 queue_for_each_hw_ctx(q
, hctx
, i
) {
239 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
240 synchronize_srcu(hctx
->srcu
);
247 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
250 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
253 * This function recovers queue into the state before quiescing
254 * which is done by blk_mq_quiesce_queue.
256 void blk_mq_unquiesce_queue(struct request_queue
*q
)
258 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
260 /* dispatch requests which are inserted during quiescing */
261 blk_mq_run_hw_queues(q
, true);
263 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
265 void blk_mq_wake_waiters(struct request_queue
*q
)
267 struct blk_mq_hw_ctx
*hctx
;
270 queue_for_each_hw_ctx(q
, hctx
, i
)
271 if (blk_mq_hw_queue_mapped(hctx
))
272 blk_mq_tag_wakeup_all(hctx
->tags
, true);
275 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
277 return blk_mq_has_free_tags(hctx
->tags
);
279 EXPORT_SYMBOL(blk_mq_can_queue
);
282 * Only need start/end time stamping if we have stats enabled, or using
285 static inline bool blk_mq_need_time_stamp(struct request
*rq
)
287 return (rq
->rq_flags
& RQF_IO_STAT
) || rq
->q
->elevator
;
290 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
291 unsigned int tag
, unsigned int op
)
293 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
294 struct request
*rq
= tags
->static_rqs
[tag
];
295 req_flags_t rq_flags
= 0;
297 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
299 rq
->internal_tag
= tag
;
301 if (data
->hctx
->flags
& BLK_MQ_F_TAG_SHARED
) {
302 rq_flags
= RQF_MQ_INFLIGHT
;
303 atomic_inc(&data
->hctx
->nr_active
);
306 rq
->internal_tag
= -1;
307 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
310 /* csd/requeue_work/fifo_time is initialized before use */
312 rq
->mq_ctx
= data
->ctx
;
313 rq
->mq_hctx
= data
->hctx
;
314 rq
->rq_flags
= rq_flags
;
316 if (data
->flags
& BLK_MQ_REQ_PREEMPT
)
317 rq
->rq_flags
|= RQF_PREEMPT
;
318 if (blk_queue_io_stat(data
->q
))
319 rq
->rq_flags
|= RQF_IO_STAT
;
320 INIT_LIST_HEAD(&rq
->queuelist
);
321 INIT_HLIST_NODE(&rq
->hash
);
322 RB_CLEAR_NODE(&rq
->rb_node
);
325 if (blk_mq_need_time_stamp(rq
))
326 rq
->start_time_ns
= ktime_get_ns();
328 rq
->start_time_ns
= 0;
329 rq
->io_start_time_ns
= 0;
330 rq
->nr_phys_segments
= 0;
331 #if defined(CONFIG_BLK_DEV_INTEGRITY)
332 rq
->nr_integrity_segments
= 0;
334 /* tag was already set */
336 WRITE_ONCE(rq
->deadline
, 0);
341 rq
->end_io_data
= NULL
;
343 data
->ctx
->rq_dispatched
[op_is_sync(op
)]++;
344 refcount_set(&rq
->ref
, 1);
348 static struct request
*blk_mq_get_request(struct request_queue
*q
,
350 struct blk_mq_alloc_data
*data
)
352 struct elevator_queue
*e
= q
->elevator
;
355 bool put_ctx_on_error
= false;
357 blk_queue_enter_live(q
);
359 if (likely(!data
->ctx
)) {
360 data
->ctx
= blk_mq_get_ctx(q
);
361 put_ctx_on_error
= true;
363 if (likely(!data
->hctx
))
364 data
->hctx
= blk_mq_map_queue(q
, data
->cmd_flags
,
366 if (data
->cmd_flags
& REQ_NOWAIT
)
367 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
370 data
->flags
|= BLK_MQ_REQ_INTERNAL
;
373 * Flush requests are special and go directly to the
374 * dispatch list. Don't include reserved tags in the
375 * limiting, as it isn't useful.
377 if (!op_is_flush(data
->cmd_flags
) &&
378 e
->type
->ops
.limit_depth
&&
379 !(data
->flags
& BLK_MQ_REQ_RESERVED
))
380 e
->type
->ops
.limit_depth(data
->cmd_flags
, data
);
382 blk_mq_tag_busy(data
->hctx
);
385 tag
= blk_mq_get_tag(data
);
386 if (tag
== BLK_MQ_TAG_FAIL
) {
387 if (put_ctx_on_error
) {
388 blk_mq_put_ctx(data
->ctx
);
395 rq
= blk_mq_rq_ctx_init(data
, tag
, data
->cmd_flags
);
396 if (!op_is_flush(data
->cmd_flags
)) {
398 if (e
&& e
->type
->ops
.prepare_request
) {
399 if (e
->type
->icq_cache
)
400 blk_mq_sched_assign_ioc(rq
);
402 e
->type
->ops
.prepare_request(rq
, bio
);
403 rq
->rq_flags
|= RQF_ELVPRIV
;
406 data
->hctx
->queued
++;
410 struct request
*blk_mq_alloc_request(struct request_queue
*q
, unsigned int op
,
411 blk_mq_req_flags_t flags
)
413 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
, .cmd_flags
= op
};
417 ret
= blk_queue_enter(q
, flags
);
421 rq
= blk_mq_get_request(q
, NULL
, &alloc_data
);
425 return ERR_PTR(-EWOULDBLOCK
);
427 blk_mq_put_ctx(alloc_data
.ctx
);
430 rq
->__sector
= (sector_t
) -1;
431 rq
->bio
= rq
->biotail
= NULL
;
434 EXPORT_SYMBOL(blk_mq_alloc_request
);
436 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
,
437 unsigned int op
, blk_mq_req_flags_t flags
, unsigned int hctx_idx
)
439 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
, .cmd_flags
= op
};
445 * If the tag allocator sleeps we could get an allocation for a
446 * different hardware context. No need to complicate the low level
447 * allocator for this for the rare use case of a command tied to
450 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
451 return ERR_PTR(-EINVAL
);
453 if (hctx_idx
>= q
->nr_hw_queues
)
454 return ERR_PTR(-EIO
);
456 ret
= blk_queue_enter(q
, flags
);
461 * Check if the hardware context is actually mapped to anything.
462 * If not tell the caller that it should skip this queue.
464 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
465 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
467 return ERR_PTR(-EXDEV
);
469 cpu
= cpumask_first_and(alloc_data
.hctx
->cpumask
, cpu_online_mask
);
470 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
472 rq
= blk_mq_get_request(q
, NULL
, &alloc_data
);
476 return ERR_PTR(-EWOULDBLOCK
);
480 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
482 static void __blk_mq_free_request(struct request
*rq
)
484 struct request_queue
*q
= rq
->q
;
485 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
486 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
487 const int sched_tag
= rq
->internal_tag
;
489 blk_pm_mark_last_busy(rq
);
492 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
494 blk_mq_put_tag(hctx
, hctx
->sched_tags
, ctx
, sched_tag
);
495 blk_mq_sched_restart(hctx
);
499 void blk_mq_free_request(struct request
*rq
)
501 struct request_queue
*q
= rq
->q
;
502 struct elevator_queue
*e
= q
->elevator
;
503 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
504 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
506 if (rq
->rq_flags
& RQF_ELVPRIV
) {
507 if (e
&& e
->type
->ops
.finish_request
)
508 e
->type
->ops
.finish_request(rq
);
510 put_io_context(rq
->elv
.icq
->ioc
);
515 ctx
->rq_completed
[rq_is_sync(rq
)]++;
516 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
517 atomic_dec(&hctx
->nr_active
);
519 if (unlikely(laptop_mode
&& !blk_rq_is_passthrough(rq
)))
520 laptop_io_completion(q
->backing_dev_info
);
524 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
525 if (refcount_dec_and_test(&rq
->ref
))
526 __blk_mq_free_request(rq
);
528 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
530 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
534 if (blk_mq_need_time_stamp(rq
))
535 now
= ktime_get_ns();
537 if (rq
->rq_flags
& RQF_STATS
) {
538 blk_mq_poll_stats_start(rq
->q
);
539 blk_stat_add(rq
, now
);
542 if (rq
->internal_tag
!= -1)
543 blk_mq_sched_completed_request(rq
, now
);
545 blk_account_io_done(rq
, now
);
548 rq_qos_done(rq
->q
, rq
);
549 rq
->end_io(rq
, error
);
551 blk_mq_free_request(rq
);
554 EXPORT_SYMBOL(__blk_mq_end_request
);
556 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
558 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
560 __blk_mq_end_request(rq
, error
);
562 EXPORT_SYMBOL(blk_mq_end_request
);
564 static void __blk_mq_complete_request_remote(void *data
)
566 struct request
*rq
= data
;
567 struct request_queue
*q
= rq
->q
;
569 q
->mq_ops
->complete(rq
);
572 static void __blk_mq_complete_request(struct request
*rq
)
574 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
575 struct request_queue
*q
= rq
->q
;
579 WRITE_ONCE(rq
->state
, MQ_RQ_COMPLETE
);
581 * Most of single queue controllers, there is only one irq vector
582 * for handling IO completion, and the only irq's affinity is set
583 * as all possible CPUs. On most of ARCHs, this affinity means the
584 * irq is handled on one specific CPU.
586 * So complete IO reqeust in softirq context in case of single queue
587 * for not degrading IO performance by irqsoff latency.
589 if (q
->nr_hw_queues
== 1) {
590 __blk_complete_request(rq
);
595 * For a polled request, always complete locallly, it's pointless
596 * to redirect the completion.
598 if ((rq
->cmd_flags
& REQ_HIPRI
) ||
599 !test_bit(QUEUE_FLAG_SAME_COMP
, &q
->queue_flags
)) {
600 q
->mq_ops
->complete(rq
);
605 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &q
->queue_flags
))
606 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
608 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
609 rq
->csd
.func
= __blk_mq_complete_request_remote
;
612 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
614 q
->mq_ops
->complete(rq
);
619 static void hctx_unlock(struct blk_mq_hw_ctx
*hctx
, int srcu_idx
)
620 __releases(hctx
->srcu
)
622 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
))
625 srcu_read_unlock(hctx
->srcu
, srcu_idx
);
628 static void hctx_lock(struct blk_mq_hw_ctx
*hctx
, int *srcu_idx
)
629 __acquires(hctx
->srcu
)
631 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
632 /* shut up gcc false positive */
636 *srcu_idx
= srcu_read_lock(hctx
->srcu
);
640 * blk_mq_complete_request - end I/O on a request
641 * @rq: the request being processed
644 * Ends all I/O on a request. It does not handle partial completions.
645 * The actual completion happens out-of-order, through a IPI handler.
647 bool blk_mq_complete_request(struct request
*rq
)
649 if (unlikely(blk_should_fake_timeout(rq
->q
)))
651 __blk_mq_complete_request(rq
);
654 EXPORT_SYMBOL(blk_mq_complete_request
);
656 int blk_mq_request_started(struct request
*rq
)
658 return blk_mq_rq_state(rq
) != MQ_RQ_IDLE
;
660 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
662 void blk_mq_start_request(struct request
*rq
)
664 struct request_queue
*q
= rq
->q
;
666 blk_mq_sched_started_request(rq
);
668 trace_block_rq_issue(q
, rq
);
670 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
671 rq
->io_start_time_ns
= ktime_get_ns();
672 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
673 rq
->throtl_size
= blk_rq_sectors(rq
);
675 rq
->rq_flags
|= RQF_STATS
;
679 WARN_ON_ONCE(blk_mq_rq_state(rq
) != MQ_RQ_IDLE
);
682 WRITE_ONCE(rq
->state
, MQ_RQ_IN_FLIGHT
);
684 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
686 * Make sure space for the drain appears. We know we can do
687 * this because max_hw_segments has been adjusted to be one
688 * fewer than the device can handle.
690 rq
->nr_phys_segments
++;
693 EXPORT_SYMBOL(blk_mq_start_request
);
695 static void __blk_mq_requeue_request(struct request
*rq
)
697 struct request_queue
*q
= rq
->q
;
699 blk_mq_put_driver_tag(rq
);
701 trace_block_rq_requeue(q
, rq
);
702 rq_qos_requeue(q
, rq
);
704 if (blk_mq_request_started(rq
)) {
705 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
706 rq
->rq_flags
&= ~RQF_TIMED_OUT
;
707 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
708 rq
->nr_phys_segments
--;
712 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
714 __blk_mq_requeue_request(rq
);
716 /* this request will be re-inserted to io scheduler queue */
717 blk_mq_sched_requeue_request(rq
);
719 BUG_ON(!list_empty(&rq
->queuelist
));
720 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
722 EXPORT_SYMBOL(blk_mq_requeue_request
);
724 static void blk_mq_requeue_work(struct work_struct
*work
)
726 struct request_queue
*q
=
727 container_of(work
, struct request_queue
, requeue_work
.work
);
729 struct request
*rq
, *next
;
731 spin_lock_irq(&q
->requeue_lock
);
732 list_splice_init(&q
->requeue_list
, &rq_list
);
733 spin_unlock_irq(&q
->requeue_lock
);
735 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
736 if (!(rq
->rq_flags
& (RQF_SOFTBARRIER
| RQF_DONTPREP
)))
739 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
740 list_del_init(&rq
->queuelist
);
742 * If RQF_DONTPREP, rq has contained some driver specific
743 * data, so insert it to hctx dispatch list to avoid any
746 if (rq
->rq_flags
& RQF_DONTPREP
)
747 blk_mq_request_bypass_insert(rq
, false);
749 blk_mq_sched_insert_request(rq
, true, false, false);
752 while (!list_empty(&rq_list
)) {
753 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
754 list_del_init(&rq
->queuelist
);
755 blk_mq_sched_insert_request(rq
, false, false, false);
758 blk_mq_run_hw_queues(q
, false);
761 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
762 bool kick_requeue_list
)
764 struct request_queue
*q
= rq
->q
;
768 * We abuse this flag that is otherwise used by the I/O scheduler to
769 * request head insertion from the workqueue.
771 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
773 spin_lock_irqsave(&q
->requeue_lock
, flags
);
775 rq
->rq_flags
|= RQF_SOFTBARRIER
;
776 list_add(&rq
->queuelist
, &q
->requeue_list
);
778 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
780 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
782 if (kick_requeue_list
)
783 blk_mq_kick_requeue_list(q
);
786 void blk_mq_kick_requeue_list(struct request_queue
*q
)
788 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
, 0);
790 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
792 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
795 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
,
796 msecs_to_jiffies(msecs
));
798 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
800 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
802 if (tag
< tags
->nr_tags
) {
803 prefetch(tags
->rqs
[tag
]);
804 return tags
->rqs
[tag
];
809 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
811 static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
812 void *priv
, bool reserved
)
815 * If we find a request that is inflight and the queue matches,
816 * we know the queue is busy. Return false to stop the iteration.
818 if (rq
->state
== MQ_RQ_IN_FLIGHT
&& rq
->q
== hctx
->queue
) {
828 bool blk_mq_queue_inflight(struct request_queue
*q
)
832 blk_mq_queue_tag_busy_iter(q
, blk_mq_rq_inflight
, &busy
);
835 EXPORT_SYMBOL_GPL(blk_mq_queue_inflight
);
837 static void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
839 req
->rq_flags
|= RQF_TIMED_OUT
;
840 if (req
->q
->mq_ops
->timeout
) {
841 enum blk_eh_timer_return ret
;
843 ret
= req
->q
->mq_ops
->timeout(req
, reserved
);
844 if (ret
== BLK_EH_DONE
)
846 WARN_ON_ONCE(ret
!= BLK_EH_RESET_TIMER
);
852 static bool blk_mq_req_expired(struct request
*rq
, unsigned long *next
)
854 unsigned long deadline
;
856 if (blk_mq_rq_state(rq
) != MQ_RQ_IN_FLIGHT
)
858 if (rq
->rq_flags
& RQF_TIMED_OUT
)
861 deadline
= READ_ONCE(rq
->deadline
);
862 if (time_after_eq(jiffies
, deadline
))
867 else if (time_after(*next
, deadline
))
872 static bool blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
873 struct request
*rq
, void *priv
, bool reserved
)
875 unsigned long *next
= priv
;
878 * Just do a quick check if it is expired before locking the request in
879 * so we're not unnecessarilly synchronizing across CPUs.
881 if (!blk_mq_req_expired(rq
, next
))
885 * We have reason to believe the request may be expired. Take a
886 * reference on the request to lock this request lifetime into its
887 * currently allocated context to prevent it from being reallocated in
888 * the event the completion by-passes this timeout handler.
890 * If the reference was already released, then the driver beat the
891 * timeout handler to posting a natural completion.
893 if (!refcount_inc_not_zero(&rq
->ref
))
897 * The request is now locked and cannot be reallocated underneath the
898 * timeout handler's processing. Re-verify this exact request is truly
899 * expired; if it is not expired, then the request was completed and
900 * reallocated as a new request.
902 if (blk_mq_req_expired(rq
, next
))
903 blk_mq_rq_timed_out(rq
, reserved
);
904 if (refcount_dec_and_test(&rq
->ref
))
905 __blk_mq_free_request(rq
);
910 static void blk_mq_timeout_work(struct work_struct
*work
)
912 struct request_queue
*q
=
913 container_of(work
, struct request_queue
, timeout_work
);
914 unsigned long next
= 0;
915 struct blk_mq_hw_ctx
*hctx
;
918 /* A deadlock might occur if a request is stuck requiring a
919 * timeout at the same time a queue freeze is waiting
920 * completion, since the timeout code would not be able to
921 * acquire the queue reference here.
923 * That's why we don't use blk_queue_enter here; instead, we use
924 * percpu_ref_tryget directly, because we need to be able to
925 * obtain a reference even in the short window between the queue
926 * starting to freeze, by dropping the first reference in
927 * blk_freeze_queue_start, and the moment the last request is
928 * consumed, marked by the instant q_usage_counter reaches
931 if (!percpu_ref_tryget(&q
->q_usage_counter
))
934 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &next
);
937 mod_timer(&q
->timeout
, next
);
940 * Request timeouts are handled as a forward rolling timer. If
941 * we end up here it means that no requests are pending and
942 * also that no request has been pending for a while. Mark
945 queue_for_each_hw_ctx(q
, hctx
, i
) {
946 /* the hctx may be unmapped, so check it here */
947 if (blk_mq_hw_queue_mapped(hctx
))
948 blk_mq_tag_idle(hctx
);
954 struct flush_busy_ctx_data
{
955 struct blk_mq_hw_ctx
*hctx
;
956 struct list_head
*list
;
959 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
961 struct flush_busy_ctx_data
*flush_data
= data
;
962 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
963 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
964 enum hctx_type type
= hctx
->type
;
966 spin_lock(&ctx
->lock
);
967 list_splice_tail_init(&ctx
->rq_lists
[type
], flush_data
->list
);
968 sbitmap_clear_bit(sb
, bitnr
);
969 spin_unlock(&ctx
->lock
);
974 * Process software queues that have been marked busy, splicing them
975 * to the for-dispatch
977 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
979 struct flush_busy_ctx_data data
= {
984 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
986 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
988 struct dispatch_rq_data
{
989 struct blk_mq_hw_ctx
*hctx
;
993 static bool dispatch_rq_from_ctx(struct sbitmap
*sb
, unsigned int bitnr
,
996 struct dispatch_rq_data
*dispatch_data
= data
;
997 struct blk_mq_hw_ctx
*hctx
= dispatch_data
->hctx
;
998 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
999 enum hctx_type type
= hctx
->type
;
1001 spin_lock(&ctx
->lock
);
1002 if (!list_empty(&ctx
->rq_lists
[type
])) {
1003 dispatch_data
->rq
= list_entry_rq(ctx
->rq_lists
[type
].next
);
1004 list_del_init(&dispatch_data
->rq
->queuelist
);
1005 if (list_empty(&ctx
->rq_lists
[type
]))
1006 sbitmap_clear_bit(sb
, bitnr
);
1008 spin_unlock(&ctx
->lock
);
1010 return !dispatch_data
->rq
;
1013 struct request
*blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx
*hctx
,
1014 struct blk_mq_ctx
*start
)
1016 unsigned off
= start
? start
->index_hw
[hctx
->type
] : 0;
1017 struct dispatch_rq_data data
= {
1022 __sbitmap_for_each_set(&hctx
->ctx_map
, off
,
1023 dispatch_rq_from_ctx
, &data
);
1028 static inline unsigned int queued_to_index(unsigned int queued
)
1033 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
1036 bool blk_mq_get_driver_tag(struct request
*rq
)
1038 struct blk_mq_alloc_data data
= {
1040 .hctx
= rq
->mq_hctx
,
1041 .flags
= BLK_MQ_REQ_NOWAIT
,
1042 .cmd_flags
= rq
->cmd_flags
,
1049 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
1050 data
.flags
|= BLK_MQ_REQ_RESERVED
;
1052 shared
= blk_mq_tag_busy(data
.hctx
);
1053 rq
->tag
= blk_mq_get_tag(&data
);
1056 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
1057 atomic_inc(&data
.hctx
->nr_active
);
1059 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
1063 return rq
->tag
!= -1;
1066 static int blk_mq_dispatch_wake(wait_queue_entry_t
*wait
, unsigned mode
,
1067 int flags
, void *key
)
1069 struct blk_mq_hw_ctx
*hctx
;
1071 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
1073 spin_lock(&hctx
->dispatch_wait_lock
);
1074 list_del_init(&wait
->entry
);
1075 spin_unlock(&hctx
->dispatch_wait_lock
);
1077 blk_mq_run_hw_queue(hctx
, true);
1082 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1083 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1084 * restart. For both cases, take care to check the condition again after
1085 * marking us as waiting.
1087 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx
*hctx
,
1090 struct wait_queue_head
*wq
;
1091 wait_queue_entry_t
*wait
;
1094 if (!(hctx
->flags
& BLK_MQ_F_TAG_SHARED
)) {
1095 blk_mq_sched_mark_restart_hctx(hctx
);
1098 * It's possible that a tag was freed in the window between the
1099 * allocation failure and adding the hardware queue to the wait
1102 * Don't clear RESTART here, someone else could have set it.
1103 * At most this will cost an extra queue run.
1105 return blk_mq_get_driver_tag(rq
);
1108 wait
= &hctx
->dispatch_wait
;
1109 if (!list_empty_careful(&wait
->entry
))
1112 wq
= &bt_wait_ptr(&hctx
->tags
->bitmap_tags
, hctx
)->wait
;
1114 spin_lock_irq(&wq
->lock
);
1115 spin_lock(&hctx
->dispatch_wait_lock
);
1116 if (!list_empty(&wait
->entry
)) {
1117 spin_unlock(&hctx
->dispatch_wait_lock
);
1118 spin_unlock_irq(&wq
->lock
);
1122 wait
->flags
&= ~WQ_FLAG_EXCLUSIVE
;
1123 __add_wait_queue(wq
, wait
);
1126 * It's possible that a tag was freed in the window between the
1127 * allocation failure and adding the hardware queue to the wait
1130 ret
= blk_mq_get_driver_tag(rq
);
1132 spin_unlock(&hctx
->dispatch_wait_lock
);
1133 spin_unlock_irq(&wq
->lock
);
1138 * We got a tag, remove ourselves from the wait queue to ensure
1139 * someone else gets the wakeup.
1141 list_del_init(&wait
->entry
);
1142 spin_unlock(&hctx
->dispatch_wait_lock
);
1143 spin_unlock_irq(&wq
->lock
);
1148 #define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
1149 #define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
1151 * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1152 * - EWMA is one simple way to compute running average value
1153 * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1154 * - take 4 as factor for avoiding to get too small(0) result, and this
1155 * factor doesn't matter because EWMA decreases exponentially
1157 static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx
*hctx
, bool busy
)
1161 if (hctx
->queue
->elevator
)
1164 ewma
= hctx
->dispatch_busy
;
1169 ewma
*= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
- 1;
1171 ewma
+= 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR
;
1172 ewma
/= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
;
1174 hctx
->dispatch_busy
= ewma
;
1177 #define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1180 * Returns true if we did some work AND can potentially do more.
1182 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
,
1185 struct blk_mq_hw_ctx
*hctx
;
1186 struct request
*rq
, *nxt
;
1187 bool no_tag
= false;
1189 blk_status_t ret
= BLK_STS_OK
;
1191 if (list_empty(list
))
1194 WARN_ON(!list_is_singular(list
) && got_budget
);
1197 * Now process all the entries, sending them to the driver.
1199 errors
= queued
= 0;
1201 struct blk_mq_queue_data bd
;
1203 rq
= list_first_entry(list
, struct request
, queuelist
);
1206 if (!got_budget
&& !blk_mq_get_dispatch_budget(hctx
))
1209 if (!blk_mq_get_driver_tag(rq
)) {
1211 * The initial allocation attempt failed, so we need to
1212 * rerun the hardware queue when a tag is freed. The
1213 * waitqueue takes care of that. If the queue is run
1214 * before we add this entry back on the dispatch list,
1215 * we'll re-run it below.
1217 if (!blk_mq_mark_tag_wait(hctx
, rq
)) {
1218 blk_mq_put_dispatch_budget(hctx
);
1220 * For non-shared tags, the RESTART check
1223 if (hctx
->flags
& BLK_MQ_F_TAG_SHARED
)
1229 list_del_init(&rq
->queuelist
);
1234 * Flag last if we have no more requests, or if we have more
1235 * but can't assign a driver tag to it.
1237 if (list_empty(list
))
1240 nxt
= list_first_entry(list
, struct request
, queuelist
);
1241 bd
.last
= !blk_mq_get_driver_tag(nxt
);
1244 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1245 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
) {
1247 * If an I/O scheduler has been configured and we got a
1248 * driver tag for the next request already, free it
1251 if (!list_empty(list
)) {
1252 nxt
= list_first_entry(list
, struct request
, queuelist
);
1253 blk_mq_put_driver_tag(nxt
);
1255 list_add(&rq
->queuelist
, list
);
1256 __blk_mq_requeue_request(rq
);
1260 if (unlikely(ret
!= BLK_STS_OK
)) {
1262 blk_mq_end_request(rq
, BLK_STS_IOERR
);
1267 } while (!list_empty(list
));
1269 hctx
->dispatched
[queued_to_index(queued
)]++;
1272 * Any items that need requeuing? Stuff them into hctx->dispatch,
1273 * that is where we will continue on next queue run.
1275 if (!list_empty(list
)) {
1279 * If we didn't flush the entire list, we could have told
1280 * the driver there was more coming, but that turned out to
1283 if (q
->mq_ops
->commit_rqs
)
1284 q
->mq_ops
->commit_rqs(hctx
);
1286 spin_lock(&hctx
->lock
);
1287 list_splice_init(list
, &hctx
->dispatch
);
1288 spin_unlock(&hctx
->lock
);
1291 * If SCHED_RESTART was set by the caller of this function and
1292 * it is no longer set that means that it was cleared by another
1293 * thread and hence that a queue rerun is needed.
1295 * If 'no_tag' is set, that means that we failed getting
1296 * a driver tag with an I/O scheduler attached. If our dispatch
1297 * waitqueue is no longer active, ensure that we run the queue
1298 * AFTER adding our entries back to the list.
1300 * If no I/O scheduler has been configured it is possible that
1301 * the hardware queue got stopped and restarted before requests
1302 * were pushed back onto the dispatch list. Rerun the queue to
1303 * avoid starvation. Notes:
1304 * - blk_mq_run_hw_queue() checks whether or not a queue has
1305 * been stopped before rerunning a queue.
1306 * - Some but not all block drivers stop a queue before
1307 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1310 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1311 * bit is set, run queue after a delay to avoid IO stalls
1312 * that could otherwise occur if the queue is idle.
1314 needs_restart
= blk_mq_sched_needs_restart(hctx
);
1315 if (!needs_restart
||
1316 (no_tag
&& list_empty_careful(&hctx
->dispatch_wait
.entry
)))
1317 blk_mq_run_hw_queue(hctx
, true);
1318 else if (needs_restart
&& (ret
== BLK_STS_RESOURCE
))
1319 blk_mq_delay_run_hw_queue(hctx
, BLK_MQ_RESOURCE_DELAY
);
1321 blk_mq_update_dispatch_busy(hctx
, true);
1324 blk_mq_update_dispatch_busy(hctx
, false);
1327 * If the host/device is unable to accept more work, inform the
1330 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
)
1333 return (queued
+ errors
) != 0;
1336 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1341 * We should be running this queue from one of the CPUs that
1344 * There are at least two related races now between setting
1345 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1346 * __blk_mq_run_hw_queue():
1348 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1349 * but later it becomes online, then this warning is harmless
1352 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1353 * but later it becomes offline, then the warning can't be
1354 * triggered, and we depend on blk-mq timeout handler to
1355 * handle dispatched requests to this hctx
1357 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1358 cpu_online(hctx
->next_cpu
)) {
1359 printk(KERN_WARNING
"run queue from wrong CPU %d, hctx %s\n",
1360 raw_smp_processor_id(),
1361 cpumask_empty(hctx
->cpumask
) ? "inactive": "active");
1366 * We can't run the queue inline with ints disabled. Ensure that
1367 * we catch bad users of this early.
1369 WARN_ON_ONCE(in_interrupt());
1371 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1373 hctx_lock(hctx
, &srcu_idx
);
1374 blk_mq_sched_dispatch_requests(hctx
);
1375 hctx_unlock(hctx
, srcu_idx
);
1378 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx
*hctx
)
1380 int cpu
= cpumask_first_and(hctx
->cpumask
, cpu_online_mask
);
1382 if (cpu
>= nr_cpu_ids
)
1383 cpu
= cpumask_first(hctx
->cpumask
);
1388 * It'd be great if the workqueue API had a way to pass
1389 * in a mask and had some smarts for more clever placement.
1390 * For now we just round-robin here, switching for every
1391 * BLK_MQ_CPU_WORK_BATCH queued items.
1393 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1396 int next_cpu
= hctx
->next_cpu
;
1398 if (hctx
->queue
->nr_hw_queues
== 1)
1399 return WORK_CPU_UNBOUND
;
1401 if (--hctx
->next_cpu_batch
<= 0) {
1403 next_cpu
= cpumask_next_and(next_cpu
, hctx
->cpumask
,
1405 if (next_cpu
>= nr_cpu_ids
)
1406 next_cpu
= blk_mq_first_mapped_cpu(hctx
);
1407 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1411 * Do unbound schedule if we can't find a online CPU for this hctx,
1412 * and it should only happen in the path of handling CPU DEAD.
1414 if (!cpu_online(next_cpu
)) {
1421 * Make sure to re-select CPU next time once after CPUs
1422 * in hctx->cpumask become online again.
1424 hctx
->next_cpu
= next_cpu
;
1425 hctx
->next_cpu_batch
= 1;
1426 return WORK_CPU_UNBOUND
;
1429 hctx
->next_cpu
= next_cpu
;
1433 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1434 unsigned long msecs
)
1436 if (unlikely(blk_mq_hctx_stopped(hctx
)))
1439 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1440 int cpu
= get_cpu();
1441 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1442 __blk_mq_run_hw_queue(hctx
);
1450 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
,
1451 msecs_to_jiffies(msecs
));
1454 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1456 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1458 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1460 bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1466 * When queue is quiesced, we may be switching io scheduler, or
1467 * updating nr_hw_queues, or other things, and we can't run queue
1468 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1470 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1473 hctx_lock(hctx
, &srcu_idx
);
1474 need_run
= !blk_queue_quiesced(hctx
->queue
) &&
1475 blk_mq_hctx_has_pending(hctx
);
1476 hctx_unlock(hctx
, srcu_idx
);
1479 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1485 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1487 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1489 struct blk_mq_hw_ctx
*hctx
;
1492 queue_for_each_hw_ctx(q
, hctx
, i
) {
1493 if (blk_mq_hctx_stopped(hctx
))
1496 blk_mq_run_hw_queue(hctx
, async
);
1499 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1502 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1503 * @q: request queue.
1505 * The caller is responsible for serializing this function against
1506 * blk_mq_{start,stop}_hw_queue().
1508 bool blk_mq_queue_stopped(struct request_queue
*q
)
1510 struct blk_mq_hw_ctx
*hctx
;
1513 queue_for_each_hw_ctx(q
, hctx
, i
)
1514 if (blk_mq_hctx_stopped(hctx
))
1519 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1522 * This function is often used for pausing .queue_rq() by driver when
1523 * there isn't enough resource or some conditions aren't satisfied, and
1524 * BLK_STS_RESOURCE is usually returned.
1526 * We do not guarantee that dispatch can be drained or blocked
1527 * after blk_mq_stop_hw_queue() returns. Please use
1528 * blk_mq_quiesce_queue() for that requirement.
1530 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1532 cancel_delayed_work(&hctx
->run_work
);
1534 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1536 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1539 * This function is often used for pausing .queue_rq() by driver when
1540 * there isn't enough resource or some conditions aren't satisfied, and
1541 * BLK_STS_RESOURCE is usually returned.
1543 * We do not guarantee that dispatch can be drained or blocked
1544 * after blk_mq_stop_hw_queues() returns. Please use
1545 * blk_mq_quiesce_queue() for that requirement.
1547 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1549 struct blk_mq_hw_ctx
*hctx
;
1552 queue_for_each_hw_ctx(q
, hctx
, i
)
1553 blk_mq_stop_hw_queue(hctx
);
1555 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1557 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1559 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1561 blk_mq_run_hw_queue(hctx
, false);
1563 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1565 void blk_mq_start_hw_queues(struct request_queue
*q
)
1567 struct blk_mq_hw_ctx
*hctx
;
1570 queue_for_each_hw_ctx(q
, hctx
, i
)
1571 blk_mq_start_hw_queue(hctx
);
1573 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1575 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1577 if (!blk_mq_hctx_stopped(hctx
))
1580 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1581 blk_mq_run_hw_queue(hctx
, async
);
1583 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1585 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1587 struct blk_mq_hw_ctx
*hctx
;
1590 queue_for_each_hw_ctx(q
, hctx
, i
)
1591 blk_mq_start_stopped_hw_queue(hctx
, async
);
1593 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1595 static void blk_mq_run_work_fn(struct work_struct
*work
)
1597 struct blk_mq_hw_ctx
*hctx
;
1599 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1602 * If we are stopped, don't run the queue.
1604 if (test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
1607 __blk_mq_run_hw_queue(hctx
);
1610 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1614 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1615 enum hctx_type type
= hctx
->type
;
1617 lockdep_assert_held(&ctx
->lock
);
1619 trace_block_rq_insert(hctx
->queue
, rq
);
1622 list_add(&rq
->queuelist
, &ctx
->rq_lists
[type
]);
1624 list_add_tail(&rq
->queuelist
, &ctx
->rq_lists
[type
]);
1627 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1630 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1632 lockdep_assert_held(&ctx
->lock
);
1634 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1635 blk_mq_hctx_mark_pending(hctx
, ctx
);
1639 * Should only be used carefully, when the caller knows we want to
1640 * bypass a potential IO scheduler on the target device.
1642 void blk_mq_request_bypass_insert(struct request
*rq
, bool run_queue
)
1644 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1646 spin_lock(&hctx
->lock
);
1647 list_add_tail(&rq
->queuelist
, &hctx
->dispatch
);
1648 spin_unlock(&hctx
->lock
);
1651 blk_mq_run_hw_queue(hctx
, false);
1654 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1655 struct list_head
*list
)
1659 enum hctx_type type
= hctx
->type
;
1662 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1665 list_for_each_entry(rq
, list
, queuelist
) {
1666 BUG_ON(rq
->mq_ctx
!= ctx
);
1667 trace_block_rq_insert(hctx
->queue
, rq
);
1670 spin_lock(&ctx
->lock
);
1671 list_splice_tail_init(list
, &ctx
->rq_lists
[type
]);
1672 blk_mq_hctx_mark_pending(hctx
, ctx
);
1673 spin_unlock(&ctx
->lock
);
1676 static int plug_rq_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1678 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1679 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1681 if (rqa
->mq_ctx
< rqb
->mq_ctx
)
1683 else if (rqa
->mq_ctx
> rqb
->mq_ctx
)
1685 else if (rqa
->mq_hctx
< rqb
->mq_hctx
)
1687 else if (rqa
->mq_hctx
> rqb
->mq_hctx
)
1690 return blk_rq_pos(rqa
) > blk_rq_pos(rqb
);
1693 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1695 struct blk_mq_hw_ctx
*this_hctx
;
1696 struct blk_mq_ctx
*this_ctx
;
1697 struct request_queue
*this_q
;
1703 list_splice_init(&plug
->mq_list
, &list
);
1706 if (plug
->rq_count
> 2 && plug
->multiple_queues
)
1707 list_sort(NULL
, &list
, plug_rq_cmp
);
1714 while (!list_empty(&list
)) {
1715 rq
= list_entry_rq(list
.next
);
1716 list_del_init(&rq
->queuelist
);
1718 if (rq
->mq_hctx
!= this_hctx
|| rq
->mq_ctx
!= this_ctx
) {
1720 trace_block_unplug(this_q
, depth
, !from_schedule
);
1721 blk_mq_sched_insert_requests(this_hctx
, this_ctx
,
1727 this_ctx
= rq
->mq_ctx
;
1728 this_hctx
= rq
->mq_hctx
;
1733 list_add_tail(&rq
->queuelist
, &rq_list
);
1737 * If 'this_hctx' is set, we know we have entries to complete
1738 * on 'rq_list'. Do those.
1741 trace_block_unplug(this_q
, depth
, !from_schedule
);
1742 blk_mq_sched_insert_requests(this_hctx
, this_ctx
, &rq_list
,
1747 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1749 blk_init_request_from_bio(rq
, bio
);
1751 blk_account_io_start(rq
, true);
1754 static blk_status_t
__blk_mq_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1756 blk_qc_t
*cookie
, bool last
)
1758 struct request_queue
*q
= rq
->q
;
1759 struct blk_mq_queue_data bd
= {
1763 blk_qc_t new_cookie
;
1766 new_cookie
= request_to_qc_t(hctx
, rq
);
1769 * For OK queue, we are done. For error, caller may kill it.
1770 * Any other error (busy), just add it to our list as we
1771 * previously would have done.
1773 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1776 blk_mq_update_dispatch_busy(hctx
, false);
1777 *cookie
= new_cookie
;
1779 case BLK_STS_RESOURCE
:
1780 case BLK_STS_DEV_RESOURCE
:
1781 blk_mq_update_dispatch_busy(hctx
, true);
1782 __blk_mq_requeue_request(rq
);
1785 blk_mq_update_dispatch_busy(hctx
, false);
1786 *cookie
= BLK_QC_T_NONE
;
1793 blk_status_t
blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1796 bool bypass
, bool last
)
1798 struct request_queue
*q
= rq
->q
;
1799 bool run_queue
= true;
1800 blk_status_t ret
= BLK_STS_RESOURCE
;
1804 hctx_lock(hctx
, &srcu_idx
);
1806 * hctx_lock is needed before checking quiesced flag.
1808 * When queue is stopped or quiesced, ignore 'bypass', insert
1809 * and return BLK_STS_OK to caller, and avoid driver to try to
1812 if (unlikely(blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
))) {
1818 if (unlikely(q
->elevator
&& !bypass
))
1821 if (!blk_mq_get_dispatch_budget(hctx
))
1824 if (!blk_mq_get_driver_tag(rq
)) {
1825 blk_mq_put_dispatch_budget(hctx
);
1830 * Always add a request that has been through
1831 *.queue_rq() to the hardware dispatch list.
1834 ret
= __blk_mq_issue_directly(hctx
, rq
, cookie
, last
);
1836 hctx_unlock(hctx
, srcu_idx
);
1840 case BLK_STS_DEV_RESOURCE
:
1841 case BLK_STS_RESOURCE
:
1843 blk_mq_request_bypass_insert(rq
, run_queue
);
1845 * We have to return BLK_STS_OK for the DM
1846 * to avoid livelock. Otherwise, we return
1847 * the real result to indicate whether the
1848 * request is direct-issued successfully.
1850 ret
= bypass
? BLK_STS_OK
: ret
;
1851 } else if (!bypass
) {
1852 blk_mq_sched_insert_request(rq
, false,
1858 blk_mq_end_request(rq
, ret
);
1865 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx
*hctx
,
1866 struct list_head
*list
)
1869 blk_status_t ret
= BLK_STS_OK
;
1871 while (!list_empty(list
)) {
1872 struct request
*rq
= list_first_entry(list
, struct request
,
1875 list_del_init(&rq
->queuelist
);
1876 if (ret
== BLK_STS_OK
)
1877 ret
= blk_mq_try_issue_directly(hctx
, rq
, &unused
,
1881 blk_mq_sched_insert_request(rq
, false, true, false);
1885 * If we didn't flush the entire list, we could have told
1886 * the driver there was more coming, but that turned out to
1889 if (ret
!= BLK_STS_OK
&& hctx
->queue
->mq_ops
->commit_rqs
)
1890 hctx
->queue
->mq_ops
->commit_rqs(hctx
);
1893 static void blk_add_rq_to_plug(struct blk_plug
*plug
, struct request
*rq
)
1895 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1897 if (!plug
->multiple_queues
&& !list_is_singular(&plug
->mq_list
)) {
1898 struct request
*tmp
;
1900 tmp
= list_first_entry(&plug
->mq_list
, struct request
,
1902 if (tmp
->q
!= rq
->q
)
1903 plug
->multiple_queues
= true;
1907 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1909 const int is_sync
= op_is_sync(bio
->bi_opf
);
1910 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1911 struct blk_mq_alloc_data data
= { .flags
= 0};
1913 struct blk_plug
*plug
;
1914 struct request
*same_queue_rq
= NULL
;
1917 blk_queue_bounce(q
, &bio
);
1919 blk_queue_split(q
, &bio
);
1921 if (!bio_integrity_prep(bio
))
1922 return BLK_QC_T_NONE
;
1924 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1925 blk_attempt_plug_merge(q
, bio
, &same_queue_rq
))
1926 return BLK_QC_T_NONE
;
1928 if (blk_mq_sched_bio_merge(q
, bio
))
1929 return BLK_QC_T_NONE
;
1931 rq_qos_throttle(q
, bio
);
1933 data
.cmd_flags
= bio
->bi_opf
;
1934 rq
= blk_mq_get_request(q
, bio
, &data
);
1935 if (unlikely(!rq
)) {
1936 rq_qos_cleanup(q
, bio
);
1937 if (bio
->bi_opf
& REQ_NOWAIT
)
1938 bio_wouldblock_error(bio
);
1939 return BLK_QC_T_NONE
;
1942 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1944 rq_qos_track(q
, rq
, bio
);
1946 cookie
= request_to_qc_t(data
.hctx
, rq
);
1948 plug
= current
->plug
;
1949 if (unlikely(is_flush_fua
)) {
1950 blk_mq_put_ctx(data
.ctx
);
1951 blk_mq_bio_to_request(rq
, bio
);
1953 /* bypass scheduler for flush rq */
1954 blk_insert_flush(rq
);
1955 blk_mq_run_hw_queue(data
.hctx
, true);
1956 } else if (plug
&& (q
->nr_hw_queues
== 1 || q
->mq_ops
->commit_rqs
)) {
1958 * Use plugging if we have a ->commit_rqs() hook as well, as
1959 * we know the driver uses bd->last in a smart fashion.
1961 unsigned int request_count
= plug
->rq_count
;
1962 struct request
*last
= NULL
;
1964 blk_mq_put_ctx(data
.ctx
);
1965 blk_mq_bio_to_request(rq
, bio
);
1968 trace_block_plug(q
);
1970 last
= list_entry_rq(plug
->mq_list
.prev
);
1972 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1973 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1974 blk_flush_plug_list(plug
, false);
1975 trace_block_plug(q
);
1978 blk_add_rq_to_plug(plug
, rq
);
1979 } else if (plug
&& !blk_queue_nomerges(q
)) {
1980 blk_mq_bio_to_request(rq
, bio
);
1983 * We do limited plugging. If the bio can be merged, do that.
1984 * Otherwise the existing request in the plug list will be
1985 * issued. So the plug list will have one request at most
1986 * The plug list might get flushed before this. If that happens,
1987 * the plug list is empty, and same_queue_rq is invalid.
1989 if (list_empty(&plug
->mq_list
))
1990 same_queue_rq
= NULL
;
1991 if (same_queue_rq
) {
1992 list_del_init(&same_queue_rq
->queuelist
);
1995 blk_add_rq_to_plug(plug
, rq
);
1997 blk_mq_put_ctx(data
.ctx
);
1999 if (same_queue_rq
) {
2000 data
.hctx
= same_queue_rq
->mq_hctx
;
2001 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
2002 &cookie
, false, true);
2004 } else if ((q
->nr_hw_queues
> 1 && is_sync
) || (!q
->elevator
&&
2005 !data
.hctx
->dispatch_busy
)) {
2006 blk_mq_put_ctx(data
.ctx
);
2007 blk_mq_bio_to_request(rq
, bio
);
2008 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
, false, true);
2010 blk_mq_put_ctx(data
.ctx
);
2011 blk_mq_bio_to_request(rq
, bio
);
2012 blk_mq_sched_insert_request(rq
, false, true, true);
2018 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2019 unsigned int hctx_idx
)
2023 if (tags
->rqs
&& set
->ops
->exit_request
) {
2026 for (i
= 0; i
< tags
->nr_tags
; i
++) {
2027 struct request
*rq
= tags
->static_rqs
[i
];
2031 set
->ops
->exit_request(set
, rq
, hctx_idx
);
2032 tags
->static_rqs
[i
] = NULL
;
2036 while (!list_empty(&tags
->page_list
)) {
2037 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
2038 list_del_init(&page
->lru
);
2040 * Remove kmemleak object previously allocated in
2041 * blk_mq_init_rq_map().
2043 kmemleak_free(page_address(page
));
2044 __free_pages(page
, page
->private);
2048 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
2052 kfree(tags
->static_rqs
);
2053 tags
->static_rqs
= NULL
;
2055 blk_mq_free_tags(tags
);
2058 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
2059 unsigned int hctx_idx
,
2060 unsigned int nr_tags
,
2061 unsigned int reserved_tags
)
2063 struct blk_mq_tags
*tags
;
2066 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], hctx_idx
);
2067 if (node
== NUMA_NO_NODE
)
2068 node
= set
->numa_node
;
2070 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
2071 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
2075 tags
->rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2076 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2079 blk_mq_free_tags(tags
);
2083 tags
->static_rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2084 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2086 if (!tags
->static_rqs
) {
2088 blk_mq_free_tags(tags
);
2095 static size_t order_to_size(unsigned int order
)
2097 return (size_t)PAGE_SIZE
<< order
;
2100 static int blk_mq_init_request(struct blk_mq_tag_set
*set
, struct request
*rq
,
2101 unsigned int hctx_idx
, int node
)
2105 if (set
->ops
->init_request
) {
2106 ret
= set
->ops
->init_request(set
, rq
, hctx_idx
, node
);
2111 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
2115 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2116 unsigned int hctx_idx
, unsigned int depth
)
2118 unsigned int i
, j
, entries_per_page
, max_order
= 4;
2119 size_t rq_size
, left
;
2122 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], hctx_idx
);
2123 if (node
== NUMA_NO_NODE
)
2124 node
= set
->numa_node
;
2126 INIT_LIST_HEAD(&tags
->page_list
);
2129 * rq_size is the size of the request plus driver payload, rounded
2130 * to the cacheline size
2132 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
2134 left
= rq_size
* depth
;
2136 for (i
= 0; i
< depth
; ) {
2137 int this_order
= max_order
;
2142 while (this_order
&& left
< order_to_size(this_order
- 1))
2146 page
= alloc_pages_node(node
,
2147 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
2153 if (order_to_size(this_order
) < rq_size
)
2160 page
->private = this_order
;
2161 list_add_tail(&page
->lru
, &tags
->page_list
);
2163 p
= page_address(page
);
2165 * Allow kmemleak to scan these pages as they contain pointers
2166 * to additional allocations like via ops->init_request().
2168 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
2169 entries_per_page
= order_to_size(this_order
) / rq_size
;
2170 to_do
= min(entries_per_page
, depth
- i
);
2171 left
-= to_do
* rq_size
;
2172 for (j
= 0; j
< to_do
; j
++) {
2173 struct request
*rq
= p
;
2175 tags
->static_rqs
[i
] = rq
;
2176 if (blk_mq_init_request(set
, rq
, hctx_idx
, node
)) {
2177 tags
->static_rqs
[i
] = NULL
;
2188 blk_mq_free_rqs(set
, tags
, hctx_idx
);
2193 * 'cpu' is going away. splice any existing rq_list entries from this
2194 * software queue to the hw queue dispatch list, and ensure that it
2197 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
2199 struct blk_mq_hw_ctx
*hctx
;
2200 struct blk_mq_ctx
*ctx
;
2202 enum hctx_type type
;
2204 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
2205 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
2208 spin_lock(&ctx
->lock
);
2209 if (!list_empty(&ctx
->rq_lists
[type
])) {
2210 list_splice_init(&ctx
->rq_lists
[type
], &tmp
);
2211 blk_mq_hctx_clear_pending(hctx
, ctx
);
2213 spin_unlock(&ctx
->lock
);
2215 if (list_empty(&tmp
))
2218 spin_lock(&hctx
->lock
);
2219 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
2220 spin_unlock(&hctx
->lock
);
2222 blk_mq_run_hw_queue(hctx
, true);
2226 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
2228 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
2232 /* hctx->ctxs will be freed in queue's release handler */
2233 static void blk_mq_exit_hctx(struct request_queue
*q
,
2234 struct blk_mq_tag_set
*set
,
2235 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
2237 if (blk_mq_hw_queue_mapped(hctx
))
2238 blk_mq_tag_idle(hctx
);
2240 if (set
->ops
->exit_request
)
2241 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
2243 if (set
->ops
->exit_hctx
)
2244 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2246 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2247 cleanup_srcu_struct(hctx
->srcu
);
2249 blk_mq_remove_cpuhp(hctx
);
2250 blk_free_flush_queue(hctx
->fq
);
2251 sbitmap_free(&hctx
->ctx_map
);
2254 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
2255 struct blk_mq_tag_set
*set
, int nr_queue
)
2257 struct blk_mq_hw_ctx
*hctx
;
2260 queue_for_each_hw_ctx(q
, hctx
, i
) {
2263 blk_mq_debugfs_unregister_hctx(hctx
);
2264 blk_mq_exit_hctx(q
, set
, hctx
, i
);
2268 static int blk_mq_init_hctx(struct request_queue
*q
,
2269 struct blk_mq_tag_set
*set
,
2270 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
2274 node
= hctx
->numa_node
;
2275 if (node
== NUMA_NO_NODE
)
2276 node
= hctx
->numa_node
= set
->numa_node
;
2278 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
2279 spin_lock_init(&hctx
->lock
);
2280 INIT_LIST_HEAD(&hctx
->dispatch
);
2282 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
2284 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
2286 hctx
->tags
= set
->tags
[hctx_idx
];
2289 * Allocate space for all possible cpus to avoid allocation at
2292 hctx
->ctxs
= kmalloc_array_node(nr_cpu_ids
, sizeof(void *),
2293 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
, node
);
2295 goto unregister_cpu_notifier
;
2297 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8),
2298 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
, node
))
2303 spin_lock_init(&hctx
->dispatch_wait_lock
);
2304 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
2305 INIT_LIST_HEAD(&hctx
->dispatch_wait
.entry
);
2307 if (set
->ops
->init_hctx
&&
2308 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
2311 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
,
2312 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
);
2316 if (blk_mq_init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
, node
))
2319 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2320 init_srcu_struct(hctx
->srcu
);
2327 if (set
->ops
->exit_hctx
)
2328 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2330 sbitmap_free(&hctx
->ctx_map
);
2333 unregister_cpu_notifier
:
2334 blk_mq_remove_cpuhp(hctx
);
2338 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2339 unsigned int nr_hw_queues
)
2341 struct blk_mq_tag_set
*set
= q
->tag_set
;
2344 for_each_possible_cpu(i
) {
2345 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2346 struct blk_mq_hw_ctx
*hctx
;
2350 spin_lock_init(&__ctx
->lock
);
2351 for (k
= HCTX_TYPE_DEFAULT
; k
< HCTX_MAX_TYPES
; k
++)
2352 INIT_LIST_HEAD(&__ctx
->rq_lists
[k
]);
2357 * Set local node, IFF we have more than one hw queue. If
2358 * not, we remain on the home node of the device
2360 for (j
= 0; j
< set
->nr_maps
; j
++) {
2361 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2362 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2363 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2368 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2372 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2373 set
->queue_depth
, set
->reserved_tags
);
2374 if (!set
->tags
[hctx_idx
])
2377 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2382 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2383 set
->tags
[hctx_idx
] = NULL
;
2387 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2388 unsigned int hctx_idx
)
2390 if (set
->tags
&& set
->tags
[hctx_idx
]) {
2391 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2392 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2393 set
->tags
[hctx_idx
] = NULL
;
2397 static void blk_mq_map_swqueue(struct request_queue
*q
)
2399 unsigned int i
, j
, hctx_idx
;
2400 struct blk_mq_hw_ctx
*hctx
;
2401 struct blk_mq_ctx
*ctx
;
2402 struct blk_mq_tag_set
*set
= q
->tag_set
;
2405 * Avoid others reading imcomplete hctx->cpumask through sysfs
2407 mutex_lock(&q
->sysfs_lock
);
2409 queue_for_each_hw_ctx(q
, hctx
, i
) {
2410 cpumask_clear(hctx
->cpumask
);
2412 hctx
->dispatch_from
= NULL
;
2416 * Map software to hardware queues.
2418 * If the cpu isn't present, the cpu is mapped to first hctx.
2420 for_each_possible_cpu(i
) {
2421 hctx_idx
= set
->map
[HCTX_TYPE_DEFAULT
].mq_map
[i
];
2422 /* unmapped hw queue can be remapped after CPU topo changed */
2423 if (!set
->tags
[hctx_idx
] &&
2424 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2426 * If tags initialization fail for some hctx,
2427 * that hctx won't be brought online. In this
2428 * case, remap the current ctx to hctx[0] which
2429 * is guaranteed to always have tags allocated
2431 set
->map
[HCTX_TYPE_DEFAULT
].mq_map
[i
] = 0;
2434 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2435 for (j
= 0; j
< set
->nr_maps
; j
++) {
2436 if (!set
->map
[j
].nr_queues
) {
2437 ctx
->hctxs
[j
] = blk_mq_map_queue_type(q
,
2438 HCTX_TYPE_DEFAULT
, i
);
2442 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2443 ctx
->hctxs
[j
] = hctx
;
2445 * If the CPU is already set in the mask, then we've
2446 * mapped this one already. This can happen if
2447 * devices share queues across queue maps.
2449 if (cpumask_test_cpu(i
, hctx
->cpumask
))
2452 cpumask_set_cpu(i
, hctx
->cpumask
);
2454 ctx
->index_hw
[hctx
->type
] = hctx
->nr_ctx
;
2455 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2458 * If the nr_ctx type overflows, we have exceeded the
2459 * amount of sw queues we can support.
2461 BUG_ON(!hctx
->nr_ctx
);
2464 for (; j
< HCTX_MAX_TYPES
; j
++)
2465 ctx
->hctxs
[j
] = blk_mq_map_queue_type(q
,
2466 HCTX_TYPE_DEFAULT
, i
);
2469 mutex_unlock(&q
->sysfs_lock
);
2471 queue_for_each_hw_ctx(q
, hctx
, i
) {
2473 * If no software queues are mapped to this hardware queue,
2474 * disable it and free the request entries.
2476 if (!hctx
->nr_ctx
) {
2477 /* Never unmap queue 0. We need it as a
2478 * fallback in case of a new remap fails
2481 if (i
&& set
->tags
[i
])
2482 blk_mq_free_map_and_requests(set
, i
);
2488 hctx
->tags
= set
->tags
[i
];
2489 WARN_ON(!hctx
->tags
);
2492 * Set the map size to the number of mapped software queues.
2493 * This is more accurate and more efficient than looping
2494 * over all possibly mapped software queues.
2496 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2499 * Initialize batch roundrobin counts
2501 hctx
->next_cpu
= blk_mq_first_mapped_cpu(hctx
);
2502 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2507 * Caller needs to ensure that we're either frozen/quiesced, or that
2508 * the queue isn't live yet.
2510 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2512 struct blk_mq_hw_ctx
*hctx
;
2515 queue_for_each_hw_ctx(q
, hctx
, i
) {
2517 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2519 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2523 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
,
2526 struct request_queue
*q
;
2528 lockdep_assert_held(&set
->tag_list_lock
);
2530 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2531 blk_mq_freeze_queue(q
);
2532 queue_set_hctx_shared(q
, shared
);
2533 blk_mq_unfreeze_queue(q
);
2537 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2539 struct blk_mq_tag_set
*set
= q
->tag_set
;
2541 mutex_lock(&set
->tag_list_lock
);
2542 list_del_rcu(&q
->tag_set_list
);
2543 if (list_is_singular(&set
->tag_list
)) {
2544 /* just transitioned to unshared */
2545 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2546 /* update existing queue */
2547 blk_mq_update_tag_set_depth(set
, false);
2549 mutex_unlock(&set
->tag_list_lock
);
2550 INIT_LIST_HEAD(&q
->tag_set_list
);
2553 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2554 struct request_queue
*q
)
2556 mutex_lock(&set
->tag_list_lock
);
2559 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2561 if (!list_empty(&set
->tag_list
) &&
2562 !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2563 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2564 /* update existing queue */
2565 blk_mq_update_tag_set_depth(set
, true);
2567 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2568 queue_set_hctx_shared(q
, true);
2569 list_add_tail_rcu(&q
->tag_set_list
, &set
->tag_list
);
2571 mutex_unlock(&set
->tag_list_lock
);
2574 /* All allocations will be freed in release handler of q->mq_kobj */
2575 static int blk_mq_alloc_ctxs(struct request_queue
*q
)
2577 struct blk_mq_ctxs
*ctxs
;
2580 ctxs
= kzalloc(sizeof(*ctxs
), GFP_KERNEL
);
2584 ctxs
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2585 if (!ctxs
->queue_ctx
)
2588 for_each_possible_cpu(cpu
) {
2589 struct blk_mq_ctx
*ctx
= per_cpu_ptr(ctxs
->queue_ctx
, cpu
);
2593 q
->mq_kobj
= &ctxs
->kobj
;
2594 q
->queue_ctx
= ctxs
->queue_ctx
;
2603 * It is the actual release handler for mq, but we do it from
2604 * request queue's release handler for avoiding use-after-free
2605 * and headache because q->mq_kobj shouldn't have been introduced,
2606 * but we can't group ctx/kctx kobj without it.
2608 void blk_mq_release(struct request_queue
*q
)
2610 struct blk_mq_hw_ctx
*hctx
;
2613 /* hctx kobj stays in hctx */
2614 queue_for_each_hw_ctx(q
, hctx
, i
) {
2617 kobject_put(&hctx
->kobj
);
2620 kfree(q
->queue_hw_ctx
);
2623 * release .mq_kobj and sw queue's kobject now because
2624 * both share lifetime with request queue.
2626 blk_mq_sysfs_deinit(q
);
2629 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2631 struct request_queue
*uninit_q
, *q
;
2633 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2635 return ERR_PTR(-ENOMEM
);
2637 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2639 blk_cleanup_queue(uninit_q
);
2643 EXPORT_SYMBOL(blk_mq_init_queue
);
2646 * Helper for setting up a queue with mq ops, given queue depth, and
2647 * the passed in mq ops flags.
2649 struct request_queue
*blk_mq_init_sq_queue(struct blk_mq_tag_set
*set
,
2650 const struct blk_mq_ops
*ops
,
2651 unsigned int queue_depth
,
2652 unsigned int set_flags
)
2654 struct request_queue
*q
;
2657 memset(set
, 0, sizeof(*set
));
2659 set
->nr_hw_queues
= 1;
2661 set
->queue_depth
= queue_depth
;
2662 set
->numa_node
= NUMA_NO_NODE
;
2663 set
->flags
= set_flags
;
2665 ret
= blk_mq_alloc_tag_set(set
);
2667 return ERR_PTR(ret
);
2669 q
= blk_mq_init_queue(set
);
2671 blk_mq_free_tag_set(set
);
2677 EXPORT_SYMBOL(blk_mq_init_sq_queue
);
2679 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set
*tag_set
)
2681 int hw_ctx_size
= sizeof(struct blk_mq_hw_ctx
);
2683 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx
, srcu
),
2684 __alignof__(struct blk_mq_hw_ctx
)) !=
2685 sizeof(struct blk_mq_hw_ctx
));
2687 if (tag_set
->flags
& BLK_MQ_F_BLOCKING
)
2688 hw_ctx_size
+= sizeof(struct srcu_struct
);
2693 static struct blk_mq_hw_ctx
*blk_mq_alloc_and_init_hctx(
2694 struct blk_mq_tag_set
*set
, struct request_queue
*q
,
2695 int hctx_idx
, int node
)
2697 struct blk_mq_hw_ctx
*hctx
;
2699 hctx
= kzalloc_node(blk_mq_hw_ctx_size(set
),
2700 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2705 if (!zalloc_cpumask_var_node(&hctx
->cpumask
,
2706 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2712 atomic_set(&hctx
->nr_active
, 0);
2713 hctx
->numa_node
= node
;
2714 hctx
->queue_num
= hctx_idx
;
2716 if (blk_mq_init_hctx(q
, set
, hctx
, hctx_idx
)) {
2717 free_cpumask_var(hctx
->cpumask
);
2721 blk_mq_hctx_kobj_init(hctx
);
2726 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2727 struct request_queue
*q
)
2730 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2732 /* protect against switching io scheduler */
2733 mutex_lock(&q
->sysfs_lock
);
2734 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2736 struct blk_mq_hw_ctx
*hctx
;
2738 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], i
);
2740 * If the hw queue has been mapped to another numa node,
2741 * we need to realloc the hctx. If allocation fails, fallback
2742 * to use the previous one.
2744 if (hctxs
[i
] && (hctxs
[i
]->numa_node
== node
))
2747 hctx
= blk_mq_alloc_and_init_hctx(set
, q
, i
, node
);
2750 blk_mq_exit_hctx(q
, set
, hctxs
[i
], i
);
2751 kobject_put(&hctxs
[i
]->kobj
);
2756 pr_warn("Allocate new hctx on node %d fails,\
2757 fallback to previous one on node %d\n",
2758 node
, hctxs
[i
]->numa_node
);
2764 * Increasing nr_hw_queues fails. Free the newly allocated
2765 * hctxs and keep the previous q->nr_hw_queues.
2767 if (i
!= set
->nr_hw_queues
) {
2768 j
= q
->nr_hw_queues
;
2772 end
= q
->nr_hw_queues
;
2773 q
->nr_hw_queues
= set
->nr_hw_queues
;
2776 for (; j
< end
; j
++) {
2777 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2781 blk_mq_free_map_and_requests(set
, j
);
2782 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2783 kobject_put(&hctx
->kobj
);
2788 mutex_unlock(&q
->sysfs_lock
);
2792 * Maximum number of hardware queues we support. For single sets, we'll never
2793 * have more than the CPUs (software queues). For multiple sets, the tag_set
2794 * user may have set ->nr_hw_queues larger.
2796 static unsigned int nr_hw_queues(struct blk_mq_tag_set
*set
)
2798 if (set
->nr_maps
== 1)
2801 return max(set
->nr_hw_queues
, nr_cpu_ids
);
2804 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2805 struct request_queue
*q
)
2807 /* mark the queue as mq asap */
2808 q
->mq_ops
= set
->ops
;
2810 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2811 blk_mq_poll_stats_bkt
,
2812 BLK_MQ_POLL_STATS_BKTS
, q
);
2816 if (blk_mq_alloc_ctxs(q
))
2819 /* init q->mq_kobj and sw queues' kobjects */
2820 blk_mq_sysfs_init(q
);
2822 q
->nr_queues
= nr_hw_queues(set
);
2823 q
->queue_hw_ctx
= kcalloc_node(q
->nr_queues
, sizeof(*(q
->queue_hw_ctx
)),
2824 GFP_KERNEL
, set
->numa_node
);
2825 if (!q
->queue_hw_ctx
)
2828 blk_mq_realloc_hw_ctxs(set
, q
);
2829 if (!q
->nr_hw_queues
)
2832 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2833 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2837 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2838 if (set
->nr_maps
> HCTX_TYPE_POLL
&&
2839 set
->map
[HCTX_TYPE_POLL
].nr_queues
)
2840 blk_queue_flag_set(QUEUE_FLAG_POLL
, q
);
2842 q
->sg_reserved_size
= INT_MAX
;
2844 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2845 INIT_LIST_HEAD(&q
->requeue_list
);
2846 spin_lock_init(&q
->requeue_lock
);
2848 blk_queue_make_request(q
, blk_mq_make_request
);
2851 * Do this after blk_queue_make_request() overrides it...
2853 q
->nr_requests
= set
->queue_depth
;
2856 * Default to classic polling
2858 q
->poll_nsec
= BLK_MQ_POLL_CLASSIC
;
2860 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2861 blk_mq_add_queue_tag_set(set
, q
);
2862 blk_mq_map_swqueue(q
);
2864 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2867 ret
= elevator_init_mq(q
);
2869 return ERR_PTR(ret
);
2875 kfree(q
->queue_hw_ctx
);
2877 blk_mq_sysfs_deinit(q
);
2880 return ERR_PTR(-ENOMEM
);
2882 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2884 void blk_mq_free_queue(struct request_queue
*q
)
2886 struct blk_mq_tag_set
*set
= q
->tag_set
;
2888 blk_mq_del_queue_tag_set(q
);
2889 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2892 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2896 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2897 if (!__blk_mq_alloc_rq_map(set
, i
))
2904 blk_mq_free_rq_map(set
->tags
[i
]);
2910 * Allocate the request maps associated with this tag_set. Note that this
2911 * may reduce the depth asked for, if memory is tight. set->queue_depth
2912 * will be updated to reflect the allocated depth.
2914 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2919 depth
= set
->queue_depth
;
2921 err
= __blk_mq_alloc_rq_maps(set
);
2925 set
->queue_depth
>>= 1;
2926 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2930 } while (set
->queue_depth
);
2932 if (!set
->queue_depth
|| err
) {
2933 pr_err("blk-mq: failed to allocate request map\n");
2937 if (depth
!= set
->queue_depth
)
2938 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2939 depth
, set
->queue_depth
);
2944 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
2946 if (set
->ops
->map_queues
&& !is_kdump_kernel()) {
2950 * transport .map_queues is usually done in the following
2953 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
2954 * mask = get_cpu_mask(queue)
2955 * for_each_cpu(cpu, mask)
2956 * set->map[x].mq_map[cpu] = queue;
2959 * When we need to remap, the table has to be cleared for
2960 * killing stale mapping since one CPU may not be mapped
2963 for (i
= 0; i
< set
->nr_maps
; i
++)
2964 blk_mq_clear_mq_map(&set
->map
[i
]);
2966 return set
->ops
->map_queues(set
);
2968 BUG_ON(set
->nr_maps
> 1);
2969 return blk_mq_map_queues(&set
->map
[HCTX_TYPE_DEFAULT
]);
2974 * Alloc a tag set to be associated with one or more request queues.
2975 * May fail with EINVAL for various error conditions. May adjust the
2976 * requested depth down, if it's too large. In that case, the set
2977 * value will be stored in set->queue_depth.
2979 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
2983 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
2985 if (!set
->nr_hw_queues
)
2987 if (!set
->queue_depth
)
2989 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
2992 if (!set
->ops
->queue_rq
)
2995 if (!set
->ops
->get_budget
^ !set
->ops
->put_budget
)
2998 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
2999 pr_info("blk-mq: reduced tag depth to %u\n",
3001 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
3006 else if (set
->nr_maps
> HCTX_MAX_TYPES
)
3010 * If a crashdump is active, then we are potentially in a very
3011 * memory constrained environment. Limit us to 1 queue and
3012 * 64 tags to prevent using too much memory.
3014 if (is_kdump_kernel()) {
3015 set
->nr_hw_queues
= 1;
3017 set
->queue_depth
= min(64U, set
->queue_depth
);
3020 * There is no use for more h/w queues than cpus if we just have
3023 if (set
->nr_maps
== 1 && set
->nr_hw_queues
> nr_cpu_ids
)
3024 set
->nr_hw_queues
= nr_cpu_ids
;
3026 set
->tags
= kcalloc_node(nr_hw_queues(set
), sizeof(struct blk_mq_tags
*),
3027 GFP_KERNEL
, set
->numa_node
);
3032 for (i
= 0; i
< set
->nr_maps
; i
++) {
3033 set
->map
[i
].mq_map
= kcalloc_node(nr_cpu_ids
,
3034 sizeof(set
->map
[i
].mq_map
[0]),
3035 GFP_KERNEL
, set
->numa_node
);
3036 if (!set
->map
[i
].mq_map
)
3037 goto out_free_mq_map
;
3038 set
->map
[i
].nr_queues
= is_kdump_kernel() ? 1 : set
->nr_hw_queues
;
3041 ret
= blk_mq_update_queue_map(set
);
3043 goto out_free_mq_map
;
3045 ret
= blk_mq_alloc_rq_maps(set
);
3047 goto out_free_mq_map
;
3049 mutex_init(&set
->tag_list_lock
);
3050 INIT_LIST_HEAD(&set
->tag_list
);
3055 for (i
= 0; i
< set
->nr_maps
; i
++) {
3056 kfree(set
->map
[i
].mq_map
);
3057 set
->map
[i
].mq_map
= NULL
;
3063 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
3065 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
3069 for (i
= 0; i
< nr_hw_queues(set
); i
++)
3070 blk_mq_free_map_and_requests(set
, i
);
3072 for (j
= 0; j
< set
->nr_maps
; j
++) {
3073 kfree(set
->map
[j
].mq_map
);
3074 set
->map
[j
].mq_map
= NULL
;
3080 EXPORT_SYMBOL(blk_mq_free_tag_set
);
3082 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
3084 struct blk_mq_tag_set
*set
= q
->tag_set
;
3085 struct blk_mq_hw_ctx
*hctx
;
3091 if (q
->nr_requests
== nr
)
3094 blk_mq_freeze_queue(q
);
3095 blk_mq_quiesce_queue(q
);
3098 queue_for_each_hw_ctx(q
, hctx
, i
) {
3102 * If we're using an MQ scheduler, just update the scheduler
3103 * queue depth. This is similar to what the old code would do.
3105 if (!hctx
->sched_tags
) {
3106 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
, nr
,
3109 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
3117 q
->nr_requests
= nr
;
3119 blk_mq_unquiesce_queue(q
);
3120 blk_mq_unfreeze_queue(q
);
3126 * request_queue and elevator_type pair.
3127 * It is just used by __blk_mq_update_nr_hw_queues to cache
3128 * the elevator_type associated with a request_queue.
3130 struct blk_mq_qe_pair
{
3131 struct list_head node
;
3132 struct request_queue
*q
;
3133 struct elevator_type
*type
;
3137 * Cache the elevator_type in qe pair list and switch the
3138 * io scheduler to 'none'
3140 static bool blk_mq_elv_switch_none(struct list_head
*head
,
3141 struct request_queue
*q
)
3143 struct blk_mq_qe_pair
*qe
;
3148 qe
= kmalloc(sizeof(*qe
), GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
);
3152 INIT_LIST_HEAD(&qe
->node
);
3154 qe
->type
= q
->elevator
->type
;
3155 list_add(&qe
->node
, head
);
3157 mutex_lock(&q
->sysfs_lock
);
3159 * After elevator_switch_mq, the previous elevator_queue will be
3160 * released by elevator_release. The reference of the io scheduler
3161 * module get by elevator_get will also be put. So we need to get
3162 * a reference of the io scheduler module here to prevent it to be
3165 __module_get(qe
->type
->elevator_owner
);
3166 elevator_switch_mq(q
, NULL
);
3167 mutex_unlock(&q
->sysfs_lock
);
3172 static void blk_mq_elv_switch_back(struct list_head
*head
,
3173 struct request_queue
*q
)
3175 struct blk_mq_qe_pair
*qe
;
3176 struct elevator_type
*t
= NULL
;
3178 list_for_each_entry(qe
, head
, node
)
3187 list_del(&qe
->node
);
3190 mutex_lock(&q
->sysfs_lock
);
3191 elevator_switch_mq(q
, t
);
3192 mutex_unlock(&q
->sysfs_lock
);
3195 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
3198 struct request_queue
*q
;
3200 int prev_nr_hw_queues
;
3202 lockdep_assert_held(&set
->tag_list_lock
);
3204 if (set
->nr_maps
== 1 && nr_hw_queues
> nr_cpu_ids
)
3205 nr_hw_queues
= nr_cpu_ids
;
3206 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
3209 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3210 blk_mq_freeze_queue(q
);
3212 * Sync with blk_mq_queue_tag_busy_iter.
3216 * Switch IO scheduler to 'none', cleaning up the data associated
3217 * with the previous scheduler. We will switch back once we are done
3218 * updating the new sw to hw queue mappings.
3220 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3221 if (!blk_mq_elv_switch_none(&head
, q
))
3224 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3225 blk_mq_debugfs_unregister_hctxs(q
);
3226 blk_mq_sysfs_unregister(q
);
3229 prev_nr_hw_queues
= set
->nr_hw_queues
;
3230 set
->nr_hw_queues
= nr_hw_queues
;
3231 blk_mq_update_queue_map(set
);
3233 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3234 blk_mq_realloc_hw_ctxs(set
, q
);
3235 if (q
->nr_hw_queues
!= set
->nr_hw_queues
) {
3236 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3237 nr_hw_queues
, prev_nr_hw_queues
);
3238 set
->nr_hw_queues
= prev_nr_hw_queues
;
3239 blk_mq_map_queues(&set
->map
[HCTX_TYPE_DEFAULT
]);
3242 blk_mq_map_swqueue(q
);
3245 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3246 blk_mq_sysfs_register(q
);
3247 blk_mq_debugfs_register_hctxs(q
);
3251 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3252 blk_mq_elv_switch_back(&head
, q
);
3254 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3255 blk_mq_unfreeze_queue(q
);
3258 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
3260 mutex_lock(&set
->tag_list_lock
);
3261 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
3262 mutex_unlock(&set
->tag_list_lock
);
3264 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
3266 /* Enable polling stats and return whether they were already enabled. */
3267 static bool blk_poll_stats_enable(struct request_queue
*q
)
3269 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3270 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS
, q
))
3272 blk_stat_add_callback(q
, q
->poll_cb
);
3276 static void blk_mq_poll_stats_start(struct request_queue
*q
)
3279 * We don't arm the callback if polling stats are not enabled or the
3280 * callback is already active.
3282 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3283 blk_stat_is_active(q
->poll_cb
))
3286 blk_stat_activate_msecs(q
->poll_cb
, 100);
3289 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
3291 struct request_queue
*q
= cb
->data
;
3294 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
3295 if (cb
->stat
[bucket
].nr_samples
)
3296 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
3300 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
3301 struct blk_mq_hw_ctx
*hctx
,
3304 unsigned long ret
= 0;
3308 * If stats collection isn't on, don't sleep but turn it on for
3311 if (!blk_poll_stats_enable(q
))
3315 * As an optimistic guess, use half of the mean service time
3316 * for this type of request. We can (and should) make this smarter.
3317 * For instance, if the completion latencies are tight, we can
3318 * get closer than just half the mean. This is especially
3319 * important on devices where the completion latencies are longer
3320 * than ~10 usec. We do use the stats for the relevant IO size
3321 * if available which does lead to better estimates.
3323 bucket
= blk_mq_poll_stats_bkt(rq
);
3327 if (q
->poll_stat
[bucket
].nr_samples
)
3328 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
3333 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
3334 struct blk_mq_hw_ctx
*hctx
,
3337 struct hrtimer_sleeper hs
;
3338 enum hrtimer_mode mode
;
3342 if (rq
->rq_flags
& RQF_MQ_POLL_SLEPT
)
3346 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3348 * 0: use half of prev avg
3349 * >0: use this specific value
3351 if (q
->poll_nsec
> 0)
3352 nsecs
= q
->poll_nsec
;
3354 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
3359 rq
->rq_flags
|= RQF_MQ_POLL_SLEPT
;
3362 * This will be replaced with the stats tracking code, using
3363 * 'avg_completion_time / 2' as the pre-sleep target.
3367 mode
= HRTIMER_MODE_REL
;
3368 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
3369 hrtimer_set_expires(&hs
.timer
, kt
);
3371 hrtimer_init_sleeper(&hs
, current
);
3373 if (blk_mq_rq_state(rq
) == MQ_RQ_COMPLETE
)
3375 set_current_state(TASK_UNINTERRUPTIBLE
);
3376 hrtimer_start_expires(&hs
.timer
, mode
);
3379 hrtimer_cancel(&hs
.timer
);
3380 mode
= HRTIMER_MODE_ABS
;
3381 } while (hs
.task
&& !signal_pending(current
));
3383 __set_current_state(TASK_RUNNING
);
3384 destroy_hrtimer_on_stack(&hs
.timer
);
3388 static bool blk_mq_poll_hybrid(struct request_queue
*q
,
3389 struct blk_mq_hw_ctx
*hctx
, blk_qc_t cookie
)
3393 if (q
->poll_nsec
== BLK_MQ_POLL_CLASSIC
)
3396 if (!blk_qc_t_is_internal(cookie
))
3397 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
3399 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
3401 * With scheduling, if the request has completed, we'll
3402 * get a NULL return here, as we clear the sched tag when
3403 * that happens. The request still remains valid, like always,
3404 * so we should be safe with just the NULL check.
3410 return blk_mq_poll_hybrid_sleep(q
, hctx
, rq
);
3414 * blk_poll - poll for IO completions
3416 * @cookie: cookie passed back at IO submission time
3417 * @spin: whether to spin for completions
3420 * Poll for completions on the passed in queue. Returns number of
3421 * completed entries found. If @spin is true, then blk_poll will continue
3422 * looping until at least one completion is found, unless the task is
3423 * otherwise marked running (or we need to reschedule).
3425 int blk_poll(struct request_queue
*q
, blk_qc_t cookie
, bool spin
)
3427 struct blk_mq_hw_ctx
*hctx
;
3430 if (!blk_qc_t_valid(cookie
) ||
3431 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
3435 blk_flush_plug_list(current
->plug
, false);
3437 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
3440 * If we sleep, have the caller restart the poll loop to reset
3441 * the state. Like for the other success return cases, the
3442 * caller is responsible for checking if the IO completed. If
3443 * the IO isn't complete, we'll get called again and will go
3444 * straight to the busy poll loop.
3446 if (blk_mq_poll_hybrid(q
, hctx
, cookie
))
3449 hctx
->poll_considered
++;
3451 state
= current
->state
;
3455 hctx
->poll_invoked
++;
3457 ret
= q
->mq_ops
->poll(hctx
);
3459 hctx
->poll_success
++;
3460 __set_current_state(TASK_RUNNING
);
3464 if (signal_pending_state(state
, current
))
3465 __set_current_state(TASK_RUNNING
);
3467 if (current
->state
== TASK_RUNNING
)
3469 if (ret
< 0 || !spin
)
3472 } while (!need_resched());
3474 __set_current_state(TASK_RUNNING
);
3477 EXPORT_SYMBOL_GPL(blk_poll
);
3479 unsigned int blk_mq_rq_cpu(struct request
*rq
)
3481 return rq
->mq_ctx
->cpu
;
3483 EXPORT_SYMBOL(blk_mq_rq_cpu
);
3485 static int __init
blk_mq_init(void)
3487 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
3488 blk_mq_hctx_notify_dead
);
3491 subsys_initcall(blk_mq_init
);