1 // SPDX-License-Identifier: GPL-2.0
3 * Block multiqueue core code
5 * Copyright (C) 2013-2014 Jens Axboe
6 * Copyright (C) 2013-2014 Christoph Hellwig
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/backing-dev.h>
11 #include <linux/bio.h>
12 #include <linux/blkdev.h>
13 #include <linux/kmemleak.h>
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <linux/workqueue.h>
18 #include <linux/smp.h>
19 #include <linux/llist.h>
20 #include <linux/list_sort.h>
21 #include <linux/cpu.h>
22 #include <linux/cache.h>
23 #include <linux/sched/sysctl.h>
24 #include <linux/sched/topology.h>
25 #include <linux/sched/signal.h>
26 #include <linux/delay.h>
27 #include <linux/crash_dump.h>
28 #include <linux/prefetch.h>
30 #include <trace/events/block.h>
32 #include <linux/blk-mq.h>
35 #include "blk-mq-debugfs.h"
36 #include "blk-mq-tag.h"
39 #include "blk-mq-sched.h"
40 #include "blk-rq-qos.h"
42 static void blk_mq_poll_stats_start(struct request_queue
*q
);
43 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
);
45 static int blk_mq_poll_stats_bkt(const struct request
*rq
)
47 int ddir
, bytes
, bucket
;
49 ddir
= rq_data_dir(rq
);
50 bytes
= blk_rq_bytes(rq
);
52 bucket
= ddir
+ 2*(ilog2(bytes
) - 9);
56 else if (bucket
>= BLK_MQ_POLL_STATS_BKTS
)
57 return ddir
+ BLK_MQ_POLL_STATS_BKTS
- 2;
63 * Check if any of the ctx, dispatch list or elevator
64 * have pending work in this hardware queue.
66 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx
*hctx
)
68 return !list_empty_careful(&hctx
->dispatch
) ||
69 sbitmap_any_bit_set(&hctx
->ctx_map
) ||
70 blk_mq_sched_has_work(hctx
);
74 * Mark this ctx as having pending work in this hardware queue
76 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx
*hctx
,
77 struct blk_mq_ctx
*ctx
)
79 const int bit
= ctx
->index_hw
[hctx
->type
];
81 if (!sbitmap_test_bit(&hctx
->ctx_map
, bit
))
82 sbitmap_set_bit(&hctx
->ctx_map
, bit
);
85 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx
*hctx
,
86 struct blk_mq_ctx
*ctx
)
88 const int bit
= ctx
->index_hw
[hctx
->type
];
90 sbitmap_clear_bit(&hctx
->ctx_map
, bit
);
94 struct hd_struct
*part
;
95 unsigned int *inflight
;
98 static bool blk_mq_check_inflight(struct blk_mq_hw_ctx
*hctx
,
99 struct request
*rq
, void *priv
,
102 struct mq_inflight
*mi
= priv
;
105 * index[0] counts the specific partition that was asked for.
107 if (rq
->part
== mi
->part
)
113 unsigned int blk_mq_in_flight(struct request_queue
*q
, struct hd_struct
*part
)
115 unsigned inflight
[2];
116 struct mq_inflight mi
= { .part
= part
, .inflight
= inflight
, };
118 inflight
[0] = inflight
[1] = 0;
119 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight
, &mi
);
124 static bool blk_mq_check_inflight_rw(struct blk_mq_hw_ctx
*hctx
,
125 struct request
*rq
, void *priv
,
128 struct mq_inflight
*mi
= priv
;
130 if (rq
->part
== mi
->part
)
131 mi
->inflight
[rq_data_dir(rq
)]++;
136 void blk_mq_in_flight_rw(struct request_queue
*q
, struct hd_struct
*part
,
137 unsigned int inflight
[2])
139 struct mq_inflight mi
= { .part
= part
, .inflight
= inflight
, };
141 inflight
[0] = inflight
[1] = 0;
142 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_inflight_rw
, &mi
);
145 void blk_freeze_queue_start(struct request_queue
*q
)
149 freeze_depth
= atomic_inc_return(&q
->mq_freeze_depth
);
150 if (freeze_depth
== 1) {
151 percpu_ref_kill(&q
->q_usage_counter
);
153 blk_mq_run_hw_queues(q
, false);
156 EXPORT_SYMBOL_GPL(blk_freeze_queue_start
);
158 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
160 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
162 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
164 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
165 unsigned long timeout
)
167 return wait_event_timeout(q
->mq_freeze_wq
,
168 percpu_ref_is_zero(&q
->q_usage_counter
),
171 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
174 * Guarantee no request is in use, so we can change any data structure of
175 * the queue afterward.
177 void blk_freeze_queue(struct request_queue
*q
)
180 * In the !blk_mq case we are only calling this to kill the
181 * q_usage_counter, otherwise this increases the freeze depth
182 * and waits for it to return to zero. For this reason there is
183 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
184 * exported to drivers as the only user for unfreeze is blk_mq.
186 blk_freeze_queue_start(q
);
187 blk_mq_freeze_queue_wait(q
);
190 void blk_mq_freeze_queue(struct request_queue
*q
)
193 * ...just an alias to keep freeze and unfreeze actions balanced
194 * in the blk_mq_* namespace
198 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
200 void blk_mq_unfreeze_queue(struct request_queue
*q
)
204 freeze_depth
= atomic_dec_return(&q
->mq_freeze_depth
);
205 WARN_ON_ONCE(freeze_depth
< 0);
207 percpu_ref_resurrect(&q
->q_usage_counter
);
208 wake_up_all(&q
->mq_freeze_wq
);
211 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
214 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
215 * mpt3sas driver such that this function can be removed.
217 void blk_mq_quiesce_queue_nowait(struct request_queue
*q
)
219 blk_queue_flag_set(QUEUE_FLAG_QUIESCED
, q
);
221 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait
);
224 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
227 * Note: this function does not prevent that the struct request end_io()
228 * callback function is invoked. Once this function is returned, we make
229 * sure no dispatch can happen until the queue is unquiesced via
230 * blk_mq_unquiesce_queue().
232 void blk_mq_quiesce_queue(struct request_queue
*q
)
234 struct blk_mq_hw_ctx
*hctx
;
238 blk_mq_quiesce_queue_nowait(q
);
240 queue_for_each_hw_ctx(q
, hctx
, i
) {
241 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
242 synchronize_srcu(hctx
->srcu
);
249 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
252 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
255 * This function recovers queue into the state before quiescing
256 * which is done by blk_mq_quiesce_queue.
258 void blk_mq_unquiesce_queue(struct request_queue
*q
)
260 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
262 /* dispatch requests which are inserted during quiescing */
263 blk_mq_run_hw_queues(q
, true);
265 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
267 void blk_mq_wake_waiters(struct request_queue
*q
)
269 struct blk_mq_hw_ctx
*hctx
;
272 queue_for_each_hw_ctx(q
, hctx
, i
)
273 if (blk_mq_hw_queue_mapped(hctx
))
274 blk_mq_tag_wakeup_all(hctx
->tags
, true);
277 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
279 return blk_mq_has_free_tags(hctx
->tags
);
281 EXPORT_SYMBOL(blk_mq_can_queue
);
284 * Only need start/end time stamping if we have stats enabled, or using
287 static inline bool blk_mq_need_time_stamp(struct request
*rq
)
289 return (rq
->rq_flags
& RQF_IO_STAT
) || rq
->q
->elevator
;
292 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
293 unsigned int tag
, unsigned int op
)
295 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
296 struct request
*rq
= tags
->static_rqs
[tag
];
297 req_flags_t rq_flags
= 0;
299 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
301 rq
->internal_tag
= tag
;
303 if (data
->hctx
->flags
& BLK_MQ_F_TAG_SHARED
) {
304 rq_flags
= RQF_MQ_INFLIGHT
;
305 atomic_inc(&data
->hctx
->nr_active
);
308 rq
->internal_tag
= -1;
309 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
312 /* csd/requeue_work/fifo_time is initialized before use */
314 rq
->mq_ctx
= data
->ctx
;
315 rq
->mq_hctx
= data
->hctx
;
316 rq
->rq_flags
= rq_flags
;
318 if (data
->flags
& BLK_MQ_REQ_PREEMPT
)
319 rq
->rq_flags
|= RQF_PREEMPT
;
320 if (blk_queue_io_stat(data
->q
))
321 rq
->rq_flags
|= RQF_IO_STAT
;
322 INIT_LIST_HEAD(&rq
->queuelist
);
323 INIT_HLIST_NODE(&rq
->hash
);
324 RB_CLEAR_NODE(&rq
->rb_node
);
327 if (blk_mq_need_time_stamp(rq
))
328 rq
->start_time_ns
= ktime_get_ns();
330 rq
->start_time_ns
= 0;
331 rq
->io_start_time_ns
= 0;
332 rq
->nr_phys_segments
= 0;
333 #if defined(CONFIG_BLK_DEV_INTEGRITY)
334 rq
->nr_integrity_segments
= 0;
336 /* tag was already set */
338 WRITE_ONCE(rq
->deadline
, 0);
343 rq
->end_io_data
= NULL
;
345 data
->ctx
->rq_dispatched
[op_is_sync(op
)]++;
346 refcount_set(&rq
->ref
, 1);
350 static struct request
*blk_mq_get_request(struct request_queue
*q
,
352 struct blk_mq_alloc_data
*data
)
354 struct elevator_queue
*e
= q
->elevator
;
357 bool put_ctx_on_error
= false;
359 blk_queue_enter_live(q
);
361 if (likely(!data
->ctx
)) {
362 data
->ctx
= blk_mq_get_ctx(q
);
363 put_ctx_on_error
= true;
365 if (likely(!data
->hctx
))
366 data
->hctx
= blk_mq_map_queue(q
, data
->cmd_flags
,
368 if (data
->cmd_flags
& REQ_NOWAIT
)
369 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
372 data
->flags
|= BLK_MQ_REQ_INTERNAL
;
375 * Flush requests are special and go directly to the
376 * dispatch list. Don't include reserved tags in the
377 * limiting, as it isn't useful.
379 if (!op_is_flush(data
->cmd_flags
) &&
380 e
->type
->ops
.limit_depth
&&
381 !(data
->flags
& BLK_MQ_REQ_RESERVED
))
382 e
->type
->ops
.limit_depth(data
->cmd_flags
, data
);
384 blk_mq_tag_busy(data
->hctx
);
387 tag
= blk_mq_get_tag(data
);
388 if (tag
== BLK_MQ_TAG_FAIL
) {
389 if (put_ctx_on_error
) {
390 blk_mq_put_ctx(data
->ctx
);
397 rq
= blk_mq_rq_ctx_init(data
, tag
, data
->cmd_flags
);
398 if (!op_is_flush(data
->cmd_flags
)) {
400 if (e
&& e
->type
->ops
.prepare_request
) {
401 if (e
->type
->icq_cache
)
402 blk_mq_sched_assign_ioc(rq
);
404 e
->type
->ops
.prepare_request(rq
, bio
);
405 rq
->rq_flags
|= RQF_ELVPRIV
;
408 data
->hctx
->queued
++;
412 struct request
*blk_mq_alloc_request(struct request_queue
*q
, unsigned int op
,
413 blk_mq_req_flags_t flags
)
415 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
, .cmd_flags
= op
};
419 ret
= blk_queue_enter(q
, flags
);
423 rq
= blk_mq_get_request(q
, NULL
, &alloc_data
);
427 return ERR_PTR(-EWOULDBLOCK
);
429 blk_mq_put_ctx(alloc_data
.ctx
);
432 rq
->__sector
= (sector_t
) -1;
433 rq
->bio
= rq
->biotail
= NULL
;
436 EXPORT_SYMBOL(blk_mq_alloc_request
);
438 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
,
439 unsigned int op
, blk_mq_req_flags_t flags
, unsigned int hctx_idx
)
441 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
, .cmd_flags
= op
};
447 * If the tag allocator sleeps we could get an allocation for a
448 * different hardware context. No need to complicate the low level
449 * allocator for this for the rare use case of a command tied to
452 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
453 return ERR_PTR(-EINVAL
);
455 if (hctx_idx
>= q
->nr_hw_queues
)
456 return ERR_PTR(-EIO
);
458 ret
= blk_queue_enter(q
, flags
);
463 * Check if the hardware context is actually mapped to anything.
464 * If not tell the caller that it should skip this queue.
466 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
467 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
469 return ERR_PTR(-EXDEV
);
471 cpu
= cpumask_first_and(alloc_data
.hctx
->cpumask
, cpu_online_mask
);
472 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
474 rq
= blk_mq_get_request(q
, NULL
, &alloc_data
);
478 return ERR_PTR(-EWOULDBLOCK
);
482 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
484 static void __blk_mq_free_request(struct request
*rq
)
486 struct request_queue
*q
= rq
->q
;
487 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
488 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
489 const int sched_tag
= rq
->internal_tag
;
491 blk_pm_mark_last_busy(rq
);
494 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
496 blk_mq_put_tag(hctx
, hctx
->sched_tags
, ctx
, sched_tag
);
497 blk_mq_sched_restart(hctx
);
501 void blk_mq_free_request(struct request
*rq
)
503 struct request_queue
*q
= rq
->q
;
504 struct elevator_queue
*e
= q
->elevator
;
505 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
506 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
508 if (rq
->rq_flags
& RQF_ELVPRIV
) {
509 if (e
&& e
->type
->ops
.finish_request
)
510 e
->type
->ops
.finish_request(rq
);
512 put_io_context(rq
->elv
.icq
->ioc
);
517 ctx
->rq_completed
[rq_is_sync(rq
)]++;
518 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
519 atomic_dec(&hctx
->nr_active
);
521 if (unlikely(laptop_mode
&& !blk_rq_is_passthrough(rq
)))
522 laptop_io_completion(q
->backing_dev_info
);
526 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
527 if (refcount_dec_and_test(&rq
->ref
))
528 __blk_mq_free_request(rq
);
530 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
532 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
536 if (blk_mq_need_time_stamp(rq
))
537 now
= ktime_get_ns();
539 if (rq
->rq_flags
& RQF_STATS
) {
540 blk_mq_poll_stats_start(rq
->q
);
541 blk_stat_add(rq
, now
);
544 if (rq
->internal_tag
!= -1)
545 blk_mq_sched_completed_request(rq
, now
);
547 blk_account_io_done(rq
, now
);
550 rq_qos_done(rq
->q
, rq
);
551 rq
->end_io(rq
, error
);
553 blk_mq_free_request(rq
);
556 EXPORT_SYMBOL(__blk_mq_end_request
);
558 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
560 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
562 __blk_mq_end_request(rq
, error
);
564 EXPORT_SYMBOL(blk_mq_end_request
);
566 static void __blk_mq_complete_request_remote(void *data
)
568 struct request
*rq
= data
;
569 struct request_queue
*q
= rq
->q
;
571 q
->mq_ops
->complete(rq
);
574 static void __blk_mq_complete_request(struct request
*rq
)
576 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
577 struct request_queue
*q
= rq
->q
;
581 WRITE_ONCE(rq
->state
, MQ_RQ_COMPLETE
);
583 * Most of single queue controllers, there is only one irq vector
584 * for handling IO completion, and the only irq's affinity is set
585 * as all possible CPUs. On most of ARCHs, this affinity means the
586 * irq is handled on one specific CPU.
588 * So complete IO reqeust in softirq context in case of single queue
589 * for not degrading IO performance by irqsoff latency.
591 if (q
->nr_hw_queues
== 1) {
592 __blk_complete_request(rq
);
597 * For a polled request, always complete locallly, it's pointless
598 * to redirect the completion.
600 if ((rq
->cmd_flags
& REQ_HIPRI
) ||
601 !test_bit(QUEUE_FLAG_SAME_COMP
, &q
->queue_flags
)) {
602 q
->mq_ops
->complete(rq
);
607 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &q
->queue_flags
))
608 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
610 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
611 rq
->csd
.func
= __blk_mq_complete_request_remote
;
614 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
616 q
->mq_ops
->complete(rq
);
621 static void hctx_unlock(struct blk_mq_hw_ctx
*hctx
, int srcu_idx
)
622 __releases(hctx
->srcu
)
624 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
))
627 srcu_read_unlock(hctx
->srcu
, srcu_idx
);
630 static void hctx_lock(struct blk_mq_hw_ctx
*hctx
, int *srcu_idx
)
631 __acquires(hctx
->srcu
)
633 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
634 /* shut up gcc false positive */
638 *srcu_idx
= srcu_read_lock(hctx
->srcu
);
642 * blk_mq_complete_request - end I/O on a request
643 * @rq: the request being processed
646 * Ends all I/O on a request. It does not handle partial completions.
647 * The actual completion happens out-of-order, through a IPI handler.
649 bool blk_mq_complete_request(struct request
*rq
)
651 if (unlikely(blk_should_fake_timeout(rq
->q
)))
653 __blk_mq_complete_request(rq
);
656 EXPORT_SYMBOL(blk_mq_complete_request
);
658 void blk_mq_complete_request_sync(struct request
*rq
)
660 WRITE_ONCE(rq
->state
, MQ_RQ_COMPLETE
);
661 rq
->q
->mq_ops
->complete(rq
);
663 EXPORT_SYMBOL_GPL(blk_mq_complete_request_sync
);
665 int blk_mq_request_started(struct request
*rq
)
667 return blk_mq_rq_state(rq
) != MQ_RQ_IDLE
;
669 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
671 void blk_mq_start_request(struct request
*rq
)
673 struct request_queue
*q
= rq
->q
;
675 blk_mq_sched_started_request(rq
);
677 trace_block_rq_issue(q
, rq
);
679 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
680 rq
->io_start_time_ns
= ktime_get_ns();
681 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
682 rq
->throtl_size
= blk_rq_sectors(rq
);
684 rq
->rq_flags
|= RQF_STATS
;
688 WARN_ON_ONCE(blk_mq_rq_state(rq
) != MQ_RQ_IDLE
);
691 WRITE_ONCE(rq
->state
, MQ_RQ_IN_FLIGHT
);
693 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
695 * Make sure space for the drain appears. We know we can do
696 * this because max_hw_segments has been adjusted to be one
697 * fewer than the device can handle.
699 rq
->nr_phys_segments
++;
702 EXPORT_SYMBOL(blk_mq_start_request
);
704 static void __blk_mq_requeue_request(struct request
*rq
)
706 struct request_queue
*q
= rq
->q
;
708 blk_mq_put_driver_tag(rq
);
710 trace_block_rq_requeue(q
, rq
);
711 rq_qos_requeue(q
, rq
);
713 if (blk_mq_request_started(rq
)) {
714 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
715 rq
->rq_flags
&= ~RQF_TIMED_OUT
;
716 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
717 rq
->nr_phys_segments
--;
721 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
723 __blk_mq_requeue_request(rq
);
725 /* this request will be re-inserted to io scheduler queue */
726 blk_mq_sched_requeue_request(rq
);
728 BUG_ON(!list_empty(&rq
->queuelist
));
729 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
731 EXPORT_SYMBOL(blk_mq_requeue_request
);
733 static void blk_mq_requeue_work(struct work_struct
*work
)
735 struct request_queue
*q
=
736 container_of(work
, struct request_queue
, requeue_work
.work
);
738 struct request
*rq
, *next
;
740 spin_lock_irq(&q
->requeue_lock
);
741 list_splice_init(&q
->requeue_list
, &rq_list
);
742 spin_unlock_irq(&q
->requeue_lock
);
744 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
745 if (!(rq
->rq_flags
& (RQF_SOFTBARRIER
| RQF_DONTPREP
)))
748 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
749 list_del_init(&rq
->queuelist
);
751 * If RQF_DONTPREP, rq has contained some driver specific
752 * data, so insert it to hctx dispatch list to avoid any
755 if (rq
->rq_flags
& RQF_DONTPREP
)
756 blk_mq_request_bypass_insert(rq
, false);
758 blk_mq_sched_insert_request(rq
, true, false, false);
761 while (!list_empty(&rq_list
)) {
762 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
763 list_del_init(&rq
->queuelist
);
764 blk_mq_sched_insert_request(rq
, false, false, false);
767 blk_mq_run_hw_queues(q
, false);
770 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
771 bool kick_requeue_list
)
773 struct request_queue
*q
= rq
->q
;
777 * We abuse this flag that is otherwise used by the I/O scheduler to
778 * request head insertion from the workqueue.
780 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
782 spin_lock_irqsave(&q
->requeue_lock
, flags
);
784 rq
->rq_flags
|= RQF_SOFTBARRIER
;
785 list_add(&rq
->queuelist
, &q
->requeue_list
);
787 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
789 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
791 if (kick_requeue_list
)
792 blk_mq_kick_requeue_list(q
);
795 void blk_mq_kick_requeue_list(struct request_queue
*q
)
797 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
, 0);
799 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
801 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
804 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
,
805 msecs_to_jiffies(msecs
));
807 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
809 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
811 if (tag
< tags
->nr_tags
) {
812 prefetch(tags
->rqs
[tag
]);
813 return tags
->rqs
[tag
];
818 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
820 static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
821 void *priv
, bool reserved
)
824 * If we find a request that is inflight and the queue matches,
825 * we know the queue is busy. Return false to stop the iteration.
827 if (rq
->state
== MQ_RQ_IN_FLIGHT
&& rq
->q
== hctx
->queue
) {
837 bool blk_mq_queue_inflight(struct request_queue
*q
)
841 blk_mq_queue_tag_busy_iter(q
, blk_mq_rq_inflight
, &busy
);
844 EXPORT_SYMBOL_GPL(blk_mq_queue_inflight
);
846 static void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
848 req
->rq_flags
|= RQF_TIMED_OUT
;
849 if (req
->q
->mq_ops
->timeout
) {
850 enum blk_eh_timer_return ret
;
852 ret
= req
->q
->mq_ops
->timeout(req
, reserved
);
853 if (ret
== BLK_EH_DONE
)
855 WARN_ON_ONCE(ret
!= BLK_EH_RESET_TIMER
);
861 static bool blk_mq_req_expired(struct request
*rq
, unsigned long *next
)
863 unsigned long deadline
;
865 if (blk_mq_rq_state(rq
) != MQ_RQ_IN_FLIGHT
)
867 if (rq
->rq_flags
& RQF_TIMED_OUT
)
870 deadline
= READ_ONCE(rq
->deadline
);
871 if (time_after_eq(jiffies
, deadline
))
876 else if (time_after(*next
, deadline
))
881 static bool blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
882 struct request
*rq
, void *priv
, bool reserved
)
884 unsigned long *next
= priv
;
887 * Just do a quick check if it is expired before locking the request in
888 * so we're not unnecessarilly synchronizing across CPUs.
890 if (!blk_mq_req_expired(rq
, next
))
894 * We have reason to believe the request may be expired. Take a
895 * reference on the request to lock this request lifetime into its
896 * currently allocated context to prevent it from being reallocated in
897 * the event the completion by-passes this timeout handler.
899 * If the reference was already released, then the driver beat the
900 * timeout handler to posting a natural completion.
902 if (!refcount_inc_not_zero(&rq
->ref
))
906 * The request is now locked and cannot be reallocated underneath the
907 * timeout handler's processing. Re-verify this exact request is truly
908 * expired; if it is not expired, then the request was completed and
909 * reallocated as a new request.
911 if (blk_mq_req_expired(rq
, next
))
912 blk_mq_rq_timed_out(rq
, reserved
);
913 if (refcount_dec_and_test(&rq
->ref
))
914 __blk_mq_free_request(rq
);
919 static void blk_mq_timeout_work(struct work_struct
*work
)
921 struct request_queue
*q
=
922 container_of(work
, struct request_queue
, timeout_work
);
923 unsigned long next
= 0;
924 struct blk_mq_hw_ctx
*hctx
;
927 /* A deadlock might occur if a request is stuck requiring a
928 * timeout at the same time a queue freeze is waiting
929 * completion, since the timeout code would not be able to
930 * acquire the queue reference here.
932 * That's why we don't use blk_queue_enter here; instead, we use
933 * percpu_ref_tryget directly, because we need to be able to
934 * obtain a reference even in the short window between the queue
935 * starting to freeze, by dropping the first reference in
936 * blk_freeze_queue_start, and the moment the last request is
937 * consumed, marked by the instant q_usage_counter reaches
940 if (!percpu_ref_tryget(&q
->q_usage_counter
))
943 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &next
);
946 mod_timer(&q
->timeout
, next
);
949 * Request timeouts are handled as a forward rolling timer. If
950 * we end up here it means that no requests are pending and
951 * also that no request has been pending for a while. Mark
954 queue_for_each_hw_ctx(q
, hctx
, i
) {
955 /* the hctx may be unmapped, so check it here */
956 if (blk_mq_hw_queue_mapped(hctx
))
957 blk_mq_tag_idle(hctx
);
963 struct flush_busy_ctx_data
{
964 struct blk_mq_hw_ctx
*hctx
;
965 struct list_head
*list
;
968 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
970 struct flush_busy_ctx_data
*flush_data
= data
;
971 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
972 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
973 enum hctx_type type
= hctx
->type
;
975 spin_lock(&ctx
->lock
);
976 list_splice_tail_init(&ctx
->rq_lists
[type
], flush_data
->list
);
977 sbitmap_clear_bit(sb
, bitnr
);
978 spin_unlock(&ctx
->lock
);
983 * Process software queues that have been marked busy, splicing them
984 * to the for-dispatch
986 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
988 struct flush_busy_ctx_data data
= {
993 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
995 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
997 struct dispatch_rq_data
{
998 struct blk_mq_hw_ctx
*hctx
;
1002 static bool dispatch_rq_from_ctx(struct sbitmap
*sb
, unsigned int bitnr
,
1005 struct dispatch_rq_data
*dispatch_data
= data
;
1006 struct blk_mq_hw_ctx
*hctx
= dispatch_data
->hctx
;
1007 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
1008 enum hctx_type type
= hctx
->type
;
1010 spin_lock(&ctx
->lock
);
1011 if (!list_empty(&ctx
->rq_lists
[type
])) {
1012 dispatch_data
->rq
= list_entry_rq(ctx
->rq_lists
[type
].next
);
1013 list_del_init(&dispatch_data
->rq
->queuelist
);
1014 if (list_empty(&ctx
->rq_lists
[type
]))
1015 sbitmap_clear_bit(sb
, bitnr
);
1017 spin_unlock(&ctx
->lock
);
1019 return !dispatch_data
->rq
;
1022 struct request
*blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx
*hctx
,
1023 struct blk_mq_ctx
*start
)
1025 unsigned off
= start
? start
->index_hw
[hctx
->type
] : 0;
1026 struct dispatch_rq_data data
= {
1031 __sbitmap_for_each_set(&hctx
->ctx_map
, off
,
1032 dispatch_rq_from_ctx
, &data
);
1037 static inline unsigned int queued_to_index(unsigned int queued
)
1042 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
1045 bool blk_mq_get_driver_tag(struct request
*rq
)
1047 struct blk_mq_alloc_data data
= {
1049 .hctx
= rq
->mq_hctx
,
1050 .flags
= BLK_MQ_REQ_NOWAIT
,
1051 .cmd_flags
= rq
->cmd_flags
,
1058 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
1059 data
.flags
|= BLK_MQ_REQ_RESERVED
;
1061 shared
= blk_mq_tag_busy(data
.hctx
);
1062 rq
->tag
= blk_mq_get_tag(&data
);
1065 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
1066 atomic_inc(&data
.hctx
->nr_active
);
1068 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
1072 return rq
->tag
!= -1;
1075 static int blk_mq_dispatch_wake(wait_queue_entry_t
*wait
, unsigned mode
,
1076 int flags
, void *key
)
1078 struct blk_mq_hw_ctx
*hctx
;
1080 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
1082 spin_lock(&hctx
->dispatch_wait_lock
);
1083 if (!list_empty(&wait
->entry
)) {
1084 struct sbitmap_queue
*sbq
;
1086 list_del_init(&wait
->entry
);
1087 sbq
= &hctx
->tags
->bitmap_tags
;
1088 atomic_dec(&sbq
->ws_active
);
1090 spin_unlock(&hctx
->dispatch_wait_lock
);
1092 blk_mq_run_hw_queue(hctx
, true);
1097 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1098 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1099 * restart. For both cases, take care to check the condition again after
1100 * marking us as waiting.
1102 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx
*hctx
,
1105 struct sbitmap_queue
*sbq
= &hctx
->tags
->bitmap_tags
;
1106 struct wait_queue_head
*wq
;
1107 wait_queue_entry_t
*wait
;
1110 if (!(hctx
->flags
& BLK_MQ_F_TAG_SHARED
)) {
1111 blk_mq_sched_mark_restart_hctx(hctx
);
1114 * It's possible that a tag was freed in the window between the
1115 * allocation failure and adding the hardware queue to the wait
1118 * Don't clear RESTART here, someone else could have set it.
1119 * At most this will cost an extra queue run.
1121 return blk_mq_get_driver_tag(rq
);
1124 wait
= &hctx
->dispatch_wait
;
1125 if (!list_empty_careful(&wait
->entry
))
1128 wq
= &bt_wait_ptr(sbq
, hctx
)->wait
;
1130 spin_lock_irq(&wq
->lock
);
1131 spin_lock(&hctx
->dispatch_wait_lock
);
1132 if (!list_empty(&wait
->entry
)) {
1133 spin_unlock(&hctx
->dispatch_wait_lock
);
1134 spin_unlock_irq(&wq
->lock
);
1138 atomic_inc(&sbq
->ws_active
);
1139 wait
->flags
&= ~WQ_FLAG_EXCLUSIVE
;
1140 __add_wait_queue(wq
, wait
);
1143 * It's possible that a tag was freed in the window between the
1144 * allocation failure and adding the hardware queue to the wait
1147 ret
= blk_mq_get_driver_tag(rq
);
1149 spin_unlock(&hctx
->dispatch_wait_lock
);
1150 spin_unlock_irq(&wq
->lock
);
1155 * We got a tag, remove ourselves from the wait queue to ensure
1156 * someone else gets the wakeup.
1158 list_del_init(&wait
->entry
);
1159 atomic_dec(&sbq
->ws_active
);
1160 spin_unlock(&hctx
->dispatch_wait_lock
);
1161 spin_unlock_irq(&wq
->lock
);
1166 #define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
1167 #define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
1169 * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1170 * - EWMA is one simple way to compute running average value
1171 * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1172 * - take 4 as factor for avoiding to get too small(0) result, and this
1173 * factor doesn't matter because EWMA decreases exponentially
1175 static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx
*hctx
, bool busy
)
1179 if (hctx
->queue
->elevator
)
1182 ewma
= hctx
->dispatch_busy
;
1187 ewma
*= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
- 1;
1189 ewma
+= 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR
;
1190 ewma
/= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
;
1192 hctx
->dispatch_busy
= ewma
;
1195 #define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1198 * Returns true if we did some work AND can potentially do more.
1200 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
,
1203 struct blk_mq_hw_ctx
*hctx
;
1204 struct request
*rq
, *nxt
;
1205 bool no_tag
= false;
1207 blk_status_t ret
= BLK_STS_OK
;
1209 if (list_empty(list
))
1212 WARN_ON(!list_is_singular(list
) && got_budget
);
1215 * Now process all the entries, sending them to the driver.
1217 errors
= queued
= 0;
1219 struct blk_mq_queue_data bd
;
1221 rq
= list_first_entry(list
, struct request
, queuelist
);
1224 if (!got_budget
&& !blk_mq_get_dispatch_budget(hctx
))
1227 if (!blk_mq_get_driver_tag(rq
)) {
1229 * The initial allocation attempt failed, so we need to
1230 * rerun the hardware queue when a tag is freed. The
1231 * waitqueue takes care of that. If the queue is run
1232 * before we add this entry back on the dispatch list,
1233 * we'll re-run it below.
1235 if (!blk_mq_mark_tag_wait(hctx
, rq
)) {
1236 blk_mq_put_dispatch_budget(hctx
);
1238 * For non-shared tags, the RESTART check
1241 if (hctx
->flags
& BLK_MQ_F_TAG_SHARED
)
1247 list_del_init(&rq
->queuelist
);
1252 * Flag last if we have no more requests, or if we have more
1253 * but can't assign a driver tag to it.
1255 if (list_empty(list
))
1258 nxt
= list_first_entry(list
, struct request
, queuelist
);
1259 bd
.last
= !blk_mq_get_driver_tag(nxt
);
1262 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1263 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
) {
1265 * If an I/O scheduler has been configured and we got a
1266 * driver tag for the next request already, free it
1269 if (!list_empty(list
)) {
1270 nxt
= list_first_entry(list
, struct request
, queuelist
);
1271 blk_mq_put_driver_tag(nxt
);
1273 list_add(&rq
->queuelist
, list
);
1274 __blk_mq_requeue_request(rq
);
1278 if (unlikely(ret
!= BLK_STS_OK
)) {
1280 blk_mq_end_request(rq
, BLK_STS_IOERR
);
1285 } while (!list_empty(list
));
1287 hctx
->dispatched
[queued_to_index(queued
)]++;
1290 * Any items that need requeuing? Stuff them into hctx->dispatch,
1291 * that is where we will continue on next queue run.
1293 if (!list_empty(list
)) {
1297 * If we didn't flush the entire list, we could have told
1298 * the driver there was more coming, but that turned out to
1301 if (q
->mq_ops
->commit_rqs
)
1302 q
->mq_ops
->commit_rqs(hctx
);
1304 spin_lock(&hctx
->lock
);
1305 list_splice_init(list
, &hctx
->dispatch
);
1306 spin_unlock(&hctx
->lock
);
1309 * If SCHED_RESTART was set by the caller of this function and
1310 * it is no longer set that means that it was cleared by another
1311 * thread and hence that a queue rerun is needed.
1313 * If 'no_tag' is set, that means that we failed getting
1314 * a driver tag with an I/O scheduler attached. If our dispatch
1315 * waitqueue is no longer active, ensure that we run the queue
1316 * AFTER adding our entries back to the list.
1318 * If no I/O scheduler has been configured it is possible that
1319 * the hardware queue got stopped and restarted before requests
1320 * were pushed back onto the dispatch list. Rerun the queue to
1321 * avoid starvation. Notes:
1322 * - blk_mq_run_hw_queue() checks whether or not a queue has
1323 * been stopped before rerunning a queue.
1324 * - Some but not all block drivers stop a queue before
1325 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1328 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1329 * bit is set, run queue after a delay to avoid IO stalls
1330 * that could otherwise occur if the queue is idle.
1332 needs_restart
= blk_mq_sched_needs_restart(hctx
);
1333 if (!needs_restart
||
1334 (no_tag
&& list_empty_careful(&hctx
->dispatch_wait
.entry
)))
1335 blk_mq_run_hw_queue(hctx
, true);
1336 else if (needs_restart
&& (ret
== BLK_STS_RESOURCE
))
1337 blk_mq_delay_run_hw_queue(hctx
, BLK_MQ_RESOURCE_DELAY
);
1339 blk_mq_update_dispatch_busy(hctx
, true);
1342 blk_mq_update_dispatch_busy(hctx
, false);
1345 * If the host/device is unable to accept more work, inform the
1348 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
)
1351 return (queued
+ errors
) != 0;
1354 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1359 * We should be running this queue from one of the CPUs that
1362 * There are at least two related races now between setting
1363 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1364 * __blk_mq_run_hw_queue():
1366 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1367 * but later it becomes online, then this warning is harmless
1370 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1371 * but later it becomes offline, then the warning can't be
1372 * triggered, and we depend on blk-mq timeout handler to
1373 * handle dispatched requests to this hctx
1375 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1376 cpu_online(hctx
->next_cpu
)) {
1377 printk(KERN_WARNING
"run queue from wrong CPU %d, hctx %s\n",
1378 raw_smp_processor_id(),
1379 cpumask_empty(hctx
->cpumask
) ? "inactive": "active");
1384 * We can't run the queue inline with ints disabled. Ensure that
1385 * we catch bad users of this early.
1387 WARN_ON_ONCE(in_interrupt());
1389 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1391 hctx_lock(hctx
, &srcu_idx
);
1392 blk_mq_sched_dispatch_requests(hctx
);
1393 hctx_unlock(hctx
, srcu_idx
);
1396 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx
*hctx
)
1398 int cpu
= cpumask_first_and(hctx
->cpumask
, cpu_online_mask
);
1400 if (cpu
>= nr_cpu_ids
)
1401 cpu
= cpumask_first(hctx
->cpumask
);
1406 * It'd be great if the workqueue API had a way to pass
1407 * in a mask and had some smarts for more clever placement.
1408 * For now we just round-robin here, switching for every
1409 * BLK_MQ_CPU_WORK_BATCH queued items.
1411 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1414 int next_cpu
= hctx
->next_cpu
;
1416 if (hctx
->queue
->nr_hw_queues
== 1)
1417 return WORK_CPU_UNBOUND
;
1419 if (--hctx
->next_cpu_batch
<= 0) {
1421 next_cpu
= cpumask_next_and(next_cpu
, hctx
->cpumask
,
1423 if (next_cpu
>= nr_cpu_ids
)
1424 next_cpu
= blk_mq_first_mapped_cpu(hctx
);
1425 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1429 * Do unbound schedule if we can't find a online CPU for this hctx,
1430 * and it should only happen in the path of handling CPU DEAD.
1432 if (!cpu_online(next_cpu
)) {
1439 * Make sure to re-select CPU next time once after CPUs
1440 * in hctx->cpumask become online again.
1442 hctx
->next_cpu
= next_cpu
;
1443 hctx
->next_cpu_batch
= 1;
1444 return WORK_CPU_UNBOUND
;
1447 hctx
->next_cpu
= next_cpu
;
1451 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1452 unsigned long msecs
)
1454 if (unlikely(blk_mq_hctx_stopped(hctx
)))
1457 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1458 int cpu
= get_cpu();
1459 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1460 __blk_mq_run_hw_queue(hctx
);
1468 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
,
1469 msecs_to_jiffies(msecs
));
1472 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1474 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1476 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1478 bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1484 * When queue is quiesced, we may be switching io scheduler, or
1485 * updating nr_hw_queues, or other things, and we can't run queue
1486 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1488 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1491 hctx_lock(hctx
, &srcu_idx
);
1492 need_run
= !blk_queue_quiesced(hctx
->queue
) &&
1493 blk_mq_hctx_has_pending(hctx
);
1494 hctx_unlock(hctx
, srcu_idx
);
1497 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1503 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1505 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1507 struct blk_mq_hw_ctx
*hctx
;
1510 queue_for_each_hw_ctx(q
, hctx
, i
) {
1511 if (blk_mq_hctx_stopped(hctx
))
1514 blk_mq_run_hw_queue(hctx
, async
);
1517 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1520 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1521 * @q: request queue.
1523 * The caller is responsible for serializing this function against
1524 * blk_mq_{start,stop}_hw_queue().
1526 bool blk_mq_queue_stopped(struct request_queue
*q
)
1528 struct blk_mq_hw_ctx
*hctx
;
1531 queue_for_each_hw_ctx(q
, hctx
, i
)
1532 if (blk_mq_hctx_stopped(hctx
))
1537 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1540 * This function is often used for pausing .queue_rq() by driver when
1541 * there isn't enough resource or some conditions aren't satisfied, and
1542 * BLK_STS_RESOURCE is usually returned.
1544 * We do not guarantee that dispatch can be drained or blocked
1545 * after blk_mq_stop_hw_queue() returns. Please use
1546 * blk_mq_quiesce_queue() for that requirement.
1548 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1550 cancel_delayed_work(&hctx
->run_work
);
1552 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1554 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1557 * This function is often used for pausing .queue_rq() by driver when
1558 * there isn't enough resource or some conditions aren't satisfied, and
1559 * BLK_STS_RESOURCE is usually returned.
1561 * We do not guarantee that dispatch can be drained or blocked
1562 * after blk_mq_stop_hw_queues() returns. Please use
1563 * blk_mq_quiesce_queue() for that requirement.
1565 void blk_mq_stop_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_stop_hw_queue(hctx
);
1573 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1575 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1577 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1579 blk_mq_run_hw_queue(hctx
, false);
1581 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1583 void blk_mq_start_hw_queues(struct request_queue
*q
)
1585 struct blk_mq_hw_ctx
*hctx
;
1588 queue_for_each_hw_ctx(q
, hctx
, i
)
1589 blk_mq_start_hw_queue(hctx
);
1591 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1593 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1595 if (!blk_mq_hctx_stopped(hctx
))
1598 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1599 blk_mq_run_hw_queue(hctx
, async
);
1601 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1603 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1605 struct blk_mq_hw_ctx
*hctx
;
1608 queue_for_each_hw_ctx(q
, hctx
, i
)
1609 blk_mq_start_stopped_hw_queue(hctx
, async
);
1611 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1613 static void blk_mq_run_work_fn(struct work_struct
*work
)
1615 struct blk_mq_hw_ctx
*hctx
;
1617 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1620 * If we are stopped, don't run the queue.
1622 if (test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
1625 __blk_mq_run_hw_queue(hctx
);
1628 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1632 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1633 enum hctx_type type
= hctx
->type
;
1635 lockdep_assert_held(&ctx
->lock
);
1637 trace_block_rq_insert(hctx
->queue
, rq
);
1640 list_add(&rq
->queuelist
, &ctx
->rq_lists
[type
]);
1642 list_add_tail(&rq
->queuelist
, &ctx
->rq_lists
[type
]);
1645 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1648 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1650 lockdep_assert_held(&ctx
->lock
);
1652 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1653 blk_mq_hctx_mark_pending(hctx
, ctx
);
1657 * Should only be used carefully, when the caller knows we want to
1658 * bypass a potential IO scheduler on the target device.
1660 void blk_mq_request_bypass_insert(struct request
*rq
, bool run_queue
)
1662 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1664 spin_lock(&hctx
->lock
);
1665 list_add_tail(&rq
->queuelist
, &hctx
->dispatch
);
1666 spin_unlock(&hctx
->lock
);
1669 blk_mq_run_hw_queue(hctx
, false);
1672 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1673 struct list_head
*list
)
1677 enum hctx_type type
= hctx
->type
;
1680 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1683 list_for_each_entry(rq
, list
, queuelist
) {
1684 BUG_ON(rq
->mq_ctx
!= ctx
);
1685 trace_block_rq_insert(hctx
->queue
, rq
);
1688 spin_lock(&ctx
->lock
);
1689 list_splice_tail_init(list
, &ctx
->rq_lists
[type
]);
1690 blk_mq_hctx_mark_pending(hctx
, ctx
);
1691 spin_unlock(&ctx
->lock
);
1694 static int plug_rq_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1696 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1697 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1699 if (rqa
->mq_ctx
< rqb
->mq_ctx
)
1701 else if (rqa
->mq_ctx
> rqb
->mq_ctx
)
1703 else if (rqa
->mq_hctx
< rqb
->mq_hctx
)
1705 else if (rqa
->mq_hctx
> rqb
->mq_hctx
)
1708 return blk_rq_pos(rqa
) > blk_rq_pos(rqb
);
1711 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1713 struct blk_mq_hw_ctx
*this_hctx
;
1714 struct blk_mq_ctx
*this_ctx
;
1715 struct request_queue
*this_q
;
1721 list_splice_init(&plug
->mq_list
, &list
);
1723 if (plug
->rq_count
> 2 && plug
->multiple_queues
)
1724 list_sort(NULL
, &list
, plug_rq_cmp
);
1733 while (!list_empty(&list
)) {
1734 rq
= list_entry_rq(list
.next
);
1735 list_del_init(&rq
->queuelist
);
1737 if (rq
->mq_hctx
!= this_hctx
|| rq
->mq_ctx
!= this_ctx
) {
1739 trace_block_unplug(this_q
, depth
, !from_schedule
);
1740 blk_mq_sched_insert_requests(this_hctx
, this_ctx
,
1746 this_ctx
= rq
->mq_ctx
;
1747 this_hctx
= rq
->mq_hctx
;
1752 list_add_tail(&rq
->queuelist
, &rq_list
);
1756 * If 'this_hctx' is set, we know we have entries to complete
1757 * on 'rq_list'. Do those.
1760 trace_block_unplug(this_q
, depth
, !from_schedule
);
1761 blk_mq_sched_insert_requests(this_hctx
, this_ctx
, &rq_list
,
1766 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
)
1768 blk_init_request_from_bio(rq
, bio
);
1770 blk_account_io_start(rq
, true);
1773 static blk_status_t
__blk_mq_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1775 blk_qc_t
*cookie
, bool last
)
1777 struct request_queue
*q
= rq
->q
;
1778 struct blk_mq_queue_data bd
= {
1782 blk_qc_t new_cookie
;
1785 new_cookie
= request_to_qc_t(hctx
, rq
);
1788 * For OK queue, we are done. For error, caller may kill it.
1789 * Any other error (busy), just add it to our list as we
1790 * previously would have done.
1792 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1795 blk_mq_update_dispatch_busy(hctx
, false);
1796 *cookie
= new_cookie
;
1798 case BLK_STS_RESOURCE
:
1799 case BLK_STS_DEV_RESOURCE
:
1800 blk_mq_update_dispatch_busy(hctx
, true);
1801 __blk_mq_requeue_request(rq
);
1804 blk_mq_update_dispatch_busy(hctx
, false);
1805 *cookie
= BLK_QC_T_NONE
;
1812 static blk_status_t
__blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1815 bool bypass_insert
, bool last
)
1817 struct request_queue
*q
= rq
->q
;
1818 bool run_queue
= true;
1821 * RCU or SRCU read lock is needed before checking quiesced flag.
1823 * When queue is stopped or quiesced, ignore 'bypass_insert' from
1824 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
1825 * and avoid driver to try to dispatch again.
1827 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
1829 bypass_insert
= false;
1833 if (q
->elevator
&& !bypass_insert
)
1836 if (!blk_mq_get_dispatch_budget(hctx
))
1839 if (!blk_mq_get_driver_tag(rq
)) {
1840 blk_mq_put_dispatch_budget(hctx
);
1844 return __blk_mq_issue_directly(hctx
, rq
, cookie
, last
);
1847 return BLK_STS_RESOURCE
;
1849 blk_mq_request_bypass_insert(rq
, run_queue
);
1853 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1854 struct request
*rq
, blk_qc_t
*cookie
)
1859 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1861 hctx_lock(hctx
, &srcu_idx
);
1863 ret
= __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false, true);
1864 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
)
1865 blk_mq_request_bypass_insert(rq
, true);
1866 else if (ret
!= BLK_STS_OK
)
1867 blk_mq_end_request(rq
, ret
);
1869 hctx_unlock(hctx
, srcu_idx
);
1872 blk_status_t
blk_mq_request_issue_directly(struct request
*rq
, bool last
)
1876 blk_qc_t unused_cookie
;
1877 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1879 hctx_lock(hctx
, &srcu_idx
);
1880 ret
= __blk_mq_try_issue_directly(hctx
, rq
, &unused_cookie
, true, last
);
1881 hctx_unlock(hctx
, srcu_idx
);
1886 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx
*hctx
,
1887 struct list_head
*list
)
1889 while (!list_empty(list
)) {
1891 struct request
*rq
= list_first_entry(list
, struct request
,
1894 list_del_init(&rq
->queuelist
);
1895 ret
= blk_mq_request_issue_directly(rq
, list_empty(list
));
1896 if (ret
!= BLK_STS_OK
) {
1897 if (ret
== BLK_STS_RESOURCE
||
1898 ret
== BLK_STS_DEV_RESOURCE
) {
1899 blk_mq_request_bypass_insert(rq
,
1903 blk_mq_end_request(rq
, ret
);
1908 * If we didn't flush the entire list, we could have told
1909 * the driver there was more coming, but that turned out to
1912 if (!list_empty(list
) && hctx
->queue
->mq_ops
->commit_rqs
)
1913 hctx
->queue
->mq_ops
->commit_rqs(hctx
);
1916 static void blk_add_rq_to_plug(struct blk_plug
*plug
, struct request
*rq
)
1918 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1920 if (!plug
->multiple_queues
&& !list_is_singular(&plug
->mq_list
)) {
1921 struct request
*tmp
;
1923 tmp
= list_first_entry(&plug
->mq_list
, struct request
,
1925 if (tmp
->q
!= rq
->q
)
1926 plug
->multiple_queues
= true;
1930 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1932 const int is_sync
= op_is_sync(bio
->bi_opf
);
1933 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1934 struct blk_mq_alloc_data data
= { .flags
= 0};
1936 struct blk_plug
*plug
;
1937 struct request
*same_queue_rq
= NULL
;
1940 blk_queue_bounce(q
, &bio
);
1942 blk_queue_split(q
, &bio
);
1944 if (!bio_integrity_prep(bio
))
1945 return BLK_QC_T_NONE
;
1947 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1948 blk_attempt_plug_merge(q
, bio
, &same_queue_rq
))
1949 return BLK_QC_T_NONE
;
1951 if (blk_mq_sched_bio_merge(q
, bio
))
1952 return BLK_QC_T_NONE
;
1954 rq_qos_throttle(q
, bio
);
1956 data
.cmd_flags
= bio
->bi_opf
;
1957 rq
= blk_mq_get_request(q
, bio
, &data
);
1958 if (unlikely(!rq
)) {
1959 rq_qos_cleanup(q
, bio
);
1960 if (bio
->bi_opf
& REQ_NOWAIT
)
1961 bio_wouldblock_error(bio
);
1962 return BLK_QC_T_NONE
;
1965 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1967 rq_qos_track(q
, rq
, bio
);
1969 cookie
= request_to_qc_t(data
.hctx
, rq
);
1971 plug
= current
->plug
;
1972 if (unlikely(is_flush_fua
)) {
1973 blk_mq_put_ctx(data
.ctx
);
1974 blk_mq_bio_to_request(rq
, bio
);
1976 /* bypass scheduler for flush rq */
1977 blk_insert_flush(rq
);
1978 blk_mq_run_hw_queue(data
.hctx
, true);
1979 } else if (plug
&& (q
->nr_hw_queues
== 1 || q
->mq_ops
->commit_rqs
)) {
1981 * Use plugging if we have a ->commit_rqs() hook as well, as
1982 * we know the driver uses bd->last in a smart fashion.
1984 unsigned int request_count
= plug
->rq_count
;
1985 struct request
*last
= NULL
;
1987 blk_mq_put_ctx(data
.ctx
);
1988 blk_mq_bio_to_request(rq
, bio
);
1991 trace_block_plug(q
);
1993 last
= list_entry_rq(plug
->mq_list
.prev
);
1995 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1996 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1997 blk_flush_plug_list(plug
, false);
1998 trace_block_plug(q
);
2001 blk_add_rq_to_plug(plug
, rq
);
2002 } else if (plug
&& !blk_queue_nomerges(q
)) {
2003 blk_mq_bio_to_request(rq
, bio
);
2006 * We do limited plugging. If the bio can be merged, do that.
2007 * Otherwise the existing request in the plug list will be
2008 * issued. So the plug list will have one request at most
2009 * The plug list might get flushed before this. If that happens,
2010 * the plug list is empty, and same_queue_rq is invalid.
2012 if (list_empty(&plug
->mq_list
))
2013 same_queue_rq
= NULL
;
2014 if (same_queue_rq
) {
2015 list_del_init(&same_queue_rq
->queuelist
);
2018 blk_add_rq_to_plug(plug
, rq
);
2019 trace_block_plug(q
);
2021 blk_mq_put_ctx(data
.ctx
);
2023 if (same_queue_rq
) {
2024 data
.hctx
= same_queue_rq
->mq_hctx
;
2025 trace_block_unplug(q
, 1, true);
2026 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
2029 } else if ((q
->nr_hw_queues
> 1 && is_sync
) || (!q
->elevator
&&
2030 !data
.hctx
->dispatch_busy
)) {
2031 blk_mq_put_ctx(data
.ctx
);
2032 blk_mq_bio_to_request(rq
, bio
);
2033 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
2035 blk_mq_put_ctx(data
.ctx
);
2036 blk_mq_bio_to_request(rq
, bio
);
2037 blk_mq_sched_insert_request(rq
, false, true, true);
2043 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2044 unsigned int hctx_idx
)
2048 if (tags
->rqs
&& set
->ops
->exit_request
) {
2051 for (i
= 0; i
< tags
->nr_tags
; i
++) {
2052 struct request
*rq
= tags
->static_rqs
[i
];
2056 set
->ops
->exit_request(set
, rq
, hctx_idx
);
2057 tags
->static_rqs
[i
] = NULL
;
2061 while (!list_empty(&tags
->page_list
)) {
2062 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
2063 list_del_init(&page
->lru
);
2065 * Remove kmemleak object previously allocated in
2066 * blk_mq_alloc_rqs().
2068 kmemleak_free(page_address(page
));
2069 __free_pages(page
, page
->private);
2073 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
2077 kfree(tags
->static_rqs
);
2078 tags
->static_rqs
= NULL
;
2080 blk_mq_free_tags(tags
);
2083 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
2084 unsigned int hctx_idx
,
2085 unsigned int nr_tags
,
2086 unsigned int reserved_tags
)
2088 struct blk_mq_tags
*tags
;
2091 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], hctx_idx
);
2092 if (node
== NUMA_NO_NODE
)
2093 node
= set
->numa_node
;
2095 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
2096 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
2100 tags
->rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2101 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2104 blk_mq_free_tags(tags
);
2108 tags
->static_rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2109 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2111 if (!tags
->static_rqs
) {
2113 blk_mq_free_tags(tags
);
2120 static size_t order_to_size(unsigned int order
)
2122 return (size_t)PAGE_SIZE
<< order
;
2125 static int blk_mq_init_request(struct blk_mq_tag_set
*set
, struct request
*rq
,
2126 unsigned int hctx_idx
, int node
)
2130 if (set
->ops
->init_request
) {
2131 ret
= set
->ops
->init_request(set
, rq
, hctx_idx
, node
);
2136 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
2140 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2141 unsigned int hctx_idx
, unsigned int depth
)
2143 unsigned int i
, j
, entries_per_page
, max_order
= 4;
2144 size_t rq_size
, left
;
2147 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], hctx_idx
);
2148 if (node
== NUMA_NO_NODE
)
2149 node
= set
->numa_node
;
2151 INIT_LIST_HEAD(&tags
->page_list
);
2154 * rq_size is the size of the request plus driver payload, rounded
2155 * to the cacheline size
2157 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
2159 left
= rq_size
* depth
;
2161 for (i
= 0; i
< depth
; ) {
2162 int this_order
= max_order
;
2167 while (this_order
&& left
< order_to_size(this_order
- 1))
2171 page
= alloc_pages_node(node
,
2172 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
2178 if (order_to_size(this_order
) < rq_size
)
2185 page
->private = this_order
;
2186 list_add_tail(&page
->lru
, &tags
->page_list
);
2188 p
= page_address(page
);
2190 * Allow kmemleak to scan these pages as they contain pointers
2191 * to additional allocations like via ops->init_request().
2193 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
2194 entries_per_page
= order_to_size(this_order
) / rq_size
;
2195 to_do
= min(entries_per_page
, depth
- i
);
2196 left
-= to_do
* rq_size
;
2197 for (j
= 0; j
< to_do
; j
++) {
2198 struct request
*rq
= p
;
2200 tags
->static_rqs
[i
] = rq
;
2201 if (blk_mq_init_request(set
, rq
, hctx_idx
, node
)) {
2202 tags
->static_rqs
[i
] = NULL
;
2213 blk_mq_free_rqs(set
, tags
, hctx_idx
);
2218 * 'cpu' is going away. splice any existing rq_list entries from this
2219 * software queue to the hw queue dispatch list, and ensure that it
2222 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
2224 struct blk_mq_hw_ctx
*hctx
;
2225 struct blk_mq_ctx
*ctx
;
2227 enum hctx_type type
;
2229 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
2230 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
2233 spin_lock(&ctx
->lock
);
2234 if (!list_empty(&ctx
->rq_lists
[type
])) {
2235 list_splice_init(&ctx
->rq_lists
[type
], &tmp
);
2236 blk_mq_hctx_clear_pending(hctx
, ctx
);
2238 spin_unlock(&ctx
->lock
);
2240 if (list_empty(&tmp
))
2243 spin_lock(&hctx
->lock
);
2244 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
2245 spin_unlock(&hctx
->lock
);
2247 blk_mq_run_hw_queue(hctx
, true);
2251 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
2253 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
2257 /* hctx->ctxs will be freed in queue's release handler */
2258 static void blk_mq_exit_hctx(struct request_queue
*q
,
2259 struct blk_mq_tag_set
*set
,
2260 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
2262 if (blk_mq_hw_queue_mapped(hctx
))
2263 blk_mq_tag_idle(hctx
);
2265 if (set
->ops
->exit_request
)
2266 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
2268 if (set
->ops
->exit_hctx
)
2269 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2271 blk_mq_remove_cpuhp(hctx
);
2273 spin_lock(&q
->unused_hctx_lock
);
2274 list_add(&hctx
->hctx_list
, &q
->unused_hctx_list
);
2275 spin_unlock(&q
->unused_hctx_lock
);
2278 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
2279 struct blk_mq_tag_set
*set
, int nr_queue
)
2281 struct blk_mq_hw_ctx
*hctx
;
2284 queue_for_each_hw_ctx(q
, hctx
, i
) {
2287 blk_mq_debugfs_unregister_hctx(hctx
);
2288 blk_mq_exit_hctx(q
, set
, hctx
, i
);
2292 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set
*tag_set
)
2294 int hw_ctx_size
= sizeof(struct blk_mq_hw_ctx
);
2296 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx
, srcu
),
2297 __alignof__(struct blk_mq_hw_ctx
)) !=
2298 sizeof(struct blk_mq_hw_ctx
));
2300 if (tag_set
->flags
& BLK_MQ_F_BLOCKING
)
2301 hw_ctx_size
+= sizeof(struct srcu_struct
);
2306 static int blk_mq_init_hctx(struct request_queue
*q
,
2307 struct blk_mq_tag_set
*set
,
2308 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
2310 hctx
->queue_num
= hctx_idx
;
2312 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
2314 hctx
->tags
= set
->tags
[hctx_idx
];
2316 if (set
->ops
->init_hctx
&&
2317 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
2318 goto unregister_cpu_notifier
;
2320 if (blk_mq_init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
,
2326 if (set
->ops
->exit_hctx
)
2327 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2328 unregister_cpu_notifier
:
2329 blk_mq_remove_cpuhp(hctx
);
2333 static struct blk_mq_hw_ctx
*
2334 blk_mq_alloc_hctx(struct request_queue
*q
, struct blk_mq_tag_set
*set
,
2337 struct blk_mq_hw_ctx
*hctx
;
2338 gfp_t gfp
= GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
;
2340 hctx
= kzalloc_node(blk_mq_hw_ctx_size(set
), gfp
, node
);
2342 goto fail_alloc_hctx
;
2344 if (!zalloc_cpumask_var_node(&hctx
->cpumask
, gfp
, node
))
2347 atomic_set(&hctx
->nr_active
, 0);
2348 if (node
== NUMA_NO_NODE
)
2349 node
= set
->numa_node
;
2350 hctx
->numa_node
= node
;
2352 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
2353 spin_lock_init(&hctx
->lock
);
2354 INIT_LIST_HEAD(&hctx
->dispatch
);
2356 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
2358 INIT_LIST_HEAD(&hctx
->hctx_list
);
2361 * Allocate space for all possible cpus to avoid allocation at
2364 hctx
->ctxs
= kmalloc_array_node(nr_cpu_ids
, sizeof(void *),
2369 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8),
2374 spin_lock_init(&hctx
->dispatch_wait_lock
);
2375 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
2376 INIT_LIST_HEAD(&hctx
->dispatch_wait
.entry
);
2378 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
,
2383 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2384 init_srcu_struct(hctx
->srcu
);
2385 blk_mq_hctx_kobj_init(hctx
);
2390 sbitmap_free(&hctx
->ctx_map
);
2394 free_cpumask_var(hctx
->cpumask
);
2401 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2402 unsigned int nr_hw_queues
)
2404 struct blk_mq_tag_set
*set
= q
->tag_set
;
2407 for_each_possible_cpu(i
) {
2408 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2409 struct blk_mq_hw_ctx
*hctx
;
2413 spin_lock_init(&__ctx
->lock
);
2414 for (k
= HCTX_TYPE_DEFAULT
; k
< HCTX_MAX_TYPES
; k
++)
2415 INIT_LIST_HEAD(&__ctx
->rq_lists
[k
]);
2420 * Set local node, IFF we have more than one hw queue. If
2421 * not, we remain on the home node of the device
2423 for (j
= 0; j
< set
->nr_maps
; j
++) {
2424 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2425 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2426 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2431 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2435 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2436 set
->queue_depth
, set
->reserved_tags
);
2437 if (!set
->tags
[hctx_idx
])
2440 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2445 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2446 set
->tags
[hctx_idx
] = NULL
;
2450 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2451 unsigned int hctx_idx
)
2453 if (set
->tags
&& set
->tags
[hctx_idx
]) {
2454 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2455 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2456 set
->tags
[hctx_idx
] = NULL
;
2460 static void blk_mq_map_swqueue(struct request_queue
*q
)
2462 unsigned int i
, j
, hctx_idx
;
2463 struct blk_mq_hw_ctx
*hctx
;
2464 struct blk_mq_ctx
*ctx
;
2465 struct blk_mq_tag_set
*set
= q
->tag_set
;
2468 * Avoid others reading imcomplete hctx->cpumask through sysfs
2470 mutex_lock(&q
->sysfs_lock
);
2472 queue_for_each_hw_ctx(q
, hctx
, i
) {
2473 cpumask_clear(hctx
->cpumask
);
2475 hctx
->dispatch_from
= NULL
;
2479 * Map software to hardware queues.
2481 * If the cpu isn't present, the cpu is mapped to first hctx.
2483 for_each_possible_cpu(i
) {
2484 hctx_idx
= set
->map
[HCTX_TYPE_DEFAULT
].mq_map
[i
];
2485 /* unmapped hw queue can be remapped after CPU topo changed */
2486 if (!set
->tags
[hctx_idx
] &&
2487 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2489 * If tags initialization fail for some hctx,
2490 * that hctx won't be brought online. In this
2491 * case, remap the current ctx to hctx[0] which
2492 * is guaranteed to always have tags allocated
2494 set
->map
[HCTX_TYPE_DEFAULT
].mq_map
[i
] = 0;
2497 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2498 for (j
= 0; j
< set
->nr_maps
; j
++) {
2499 if (!set
->map
[j
].nr_queues
) {
2500 ctx
->hctxs
[j
] = blk_mq_map_queue_type(q
,
2501 HCTX_TYPE_DEFAULT
, i
);
2505 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2506 ctx
->hctxs
[j
] = hctx
;
2508 * If the CPU is already set in the mask, then we've
2509 * mapped this one already. This can happen if
2510 * devices share queues across queue maps.
2512 if (cpumask_test_cpu(i
, hctx
->cpumask
))
2515 cpumask_set_cpu(i
, hctx
->cpumask
);
2517 ctx
->index_hw
[hctx
->type
] = hctx
->nr_ctx
;
2518 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2521 * If the nr_ctx type overflows, we have exceeded the
2522 * amount of sw queues we can support.
2524 BUG_ON(!hctx
->nr_ctx
);
2527 for (; j
< HCTX_MAX_TYPES
; j
++)
2528 ctx
->hctxs
[j
] = blk_mq_map_queue_type(q
,
2529 HCTX_TYPE_DEFAULT
, i
);
2532 mutex_unlock(&q
->sysfs_lock
);
2534 queue_for_each_hw_ctx(q
, hctx
, i
) {
2536 * If no software queues are mapped to this hardware queue,
2537 * disable it and free the request entries.
2539 if (!hctx
->nr_ctx
) {
2540 /* Never unmap queue 0. We need it as a
2541 * fallback in case of a new remap fails
2544 if (i
&& set
->tags
[i
])
2545 blk_mq_free_map_and_requests(set
, i
);
2551 hctx
->tags
= set
->tags
[i
];
2552 WARN_ON(!hctx
->tags
);
2555 * Set the map size to the number of mapped software queues.
2556 * This is more accurate and more efficient than looping
2557 * over all possibly mapped software queues.
2559 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2562 * Initialize batch roundrobin counts
2564 hctx
->next_cpu
= blk_mq_first_mapped_cpu(hctx
);
2565 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2570 * Caller needs to ensure that we're either frozen/quiesced, or that
2571 * the queue isn't live yet.
2573 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2575 struct blk_mq_hw_ctx
*hctx
;
2578 queue_for_each_hw_ctx(q
, hctx
, i
) {
2580 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2582 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2586 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
,
2589 struct request_queue
*q
;
2591 lockdep_assert_held(&set
->tag_list_lock
);
2593 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2594 blk_mq_freeze_queue(q
);
2595 queue_set_hctx_shared(q
, shared
);
2596 blk_mq_unfreeze_queue(q
);
2600 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2602 struct blk_mq_tag_set
*set
= q
->tag_set
;
2604 mutex_lock(&set
->tag_list_lock
);
2605 list_del_rcu(&q
->tag_set_list
);
2606 if (list_is_singular(&set
->tag_list
)) {
2607 /* just transitioned to unshared */
2608 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2609 /* update existing queue */
2610 blk_mq_update_tag_set_depth(set
, false);
2612 mutex_unlock(&set
->tag_list_lock
);
2613 INIT_LIST_HEAD(&q
->tag_set_list
);
2616 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2617 struct request_queue
*q
)
2619 mutex_lock(&set
->tag_list_lock
);
2622 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2624 if (!list_empty(&set
->tag_list
) &&
2625 !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2626 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2627 /* update existing queue */
2628 blk_mq_update_tag_set_depth(set
, true);
2630 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2631 queue_set_hctx_shared(q
, true);
2632 list_add_tail_rcu(&q
->tag_set_list
, &set
->tag_list
);
2634 mutex_unlock(&set
->tag_list_lock
);
2637 /* All allocations will be freed in release handler of q->mq_kobj */
2638 static int blk_mq_alloc_ctxs(struct request_queue
*q
)
2640 struct blk_mq_ctxs
*ctxs
;
2643 ctxs
= kzalloc(sizeof(*ctxs
), GFP_KERNEL
);
2647 ctxs
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2648 if (!ctxs
->queue_ctx
)
2651 for_each_possible_cpu(cpu
) {
2652 struct blk_mq_ctx
*ctx
= per_cpu_ptr(ctxs
->queue_ctx
, cpu
);
2656 q
->mq_kobj
= &ctxs
->kobj
;
2657 q
->queue_ctx
= ctxs
->queue_ctx
;
2666 * It is the actual release handler for mq, but we do it from
2667 * request queue's release handler for avoiding use-after-free
2668 * and headache because q->mq_kobj shouldn't have been introduced,
2669 * but we can't group ctx/kctx kobj without it.
2671 void blk_mq_release(struct request_queue
*q
)
2673 struct blk_mq_hw_ctx
*hctx
, *next
;
2676 cancel_delayed_work_sync(&q
->requeue_work
);
2678 queue_for_each_hw_ctx(q
, hctx
, i
)
2679 WARN_ON_ONCE(hctx
&& list_empty(&hctx
->hctx_list
));
2681 /* all hctx are in .unused_hctx_list now */
2682 list_for_each_entry_safe(hctx
, next
, &q
->unused_hctx_list
, hctx_list
) {
2683 list_del_init(&hctx
->hctx_list
);
2684 kobject_put(&hctx
->kobj
);
2687 kfree(q
->queue_hw_ctx
);
2690 * release .mq_kobj and sw queue's kobject now because
2691 * both share lifetime with request queue.
2693 blk_mq_sysfs_deinit(q
);
2696 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2698 struct request_queue
*uninit_q
, *q
;
2700 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2702 return ERR_PTR(-ENOMEM
);
2704 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2706 blk_cleanup_queue(uninit_q
);
2710 EXPORT_SYMBOL(blk_mq_init_queue
);
2713 * Helper for setting up a queue with mq ops, given queue depth, and
2714 * the passed in mq ops flags.
2716 struct request_queue
*blk_mq_init_sq_queue(struct blk_mq_tag_set
*set
,
2717 const struct blk_mq_ops
*ops
,
2718 unsigned int queue_depth
,
2719 unsigned int set_flags
)
2721 struct request_queue
*q
;
2724 memset(set
, 0, sizeof(*set
));
2726 set
->nr_hw_queues
= 1;
2728 set
->queue_depth
= queue_depth
;
2729 set
->numa_node
= NUMA_NO_NODE
;
2730 set
->flags
= set_flags
;
2732 ret
= blk_mq_alloc_tag_set(set
);
2734 return ERR_PTR(ret
);
2736 q
= blk_mq_init_queue(set
);
2738 blk_mq_free_tag_set(set
);
2744 EXPORT_SYMBOL(blk_mq_init_sq_queue
);
2746 static struct blk_mq_hw_ctx
*blk_mq_alloc_and_init_hctx(
2747 struct blk_mq_tag_set
*set
, struct request_queue
*q
,
2748 int hctx_idx
, int node
)
2750 struct blk_mq_hw_ctx
*hctx
= NULL
, *tmp
;
2752 /* reuse dead hctx first */
2753 spin_lock(&q
->unused_hctx_lock
);
2754 list_for_each_entry(tmp
, &q
->unused_hctx_list
, hctx_list
) {
2755 if (tmp
->numa_node
== node
) {
2761 list_del_init(&hctx
->hctx_list
);
2762 spin_unlock(&q
->unused_hctx_lock
);
2765 hctx
= blk_mq_alloc_hctx(q
, set
, node
);
2769 if (blk_mq_init_hctx(q
, set
, hctx
, hctx_idx
))
2775 kobject_put(&hctx
->kobj
);
2780 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2781 struct request_queue
*q
)
2784 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2786 /* protect against switching io scheduler */
2787 mutex_lock(&q
->sysfs_lock
);
2788 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2790 struct blk_mq_hw_ctx
*hctx
;
2792 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], i
);
2794 * If the hw queue has been mapped to another numa node,
2795 * we need to realloc the hctx. If allocation fails, fallback
2796 * to use the previous one.
2798 if (hctxs
[i
] && (hctxs
[i
]->numa_node
== node
))
2801 hctx
= blk_mq_alloc_and_init_hctx(set
, q
, i
, node
);
2804 blk_mq_exit_hctx(q
, set
, hctxs
[i
], i
);
2808 pr_warn("Allocate new hctx on node %d fails,\
2809 fallback to previous one on node %d\n",
2810 node
, hctxs
[i
]->numa_node
);
2816 * Increasing nr_hw_queues fails. Free the newly allocated
2817 * hctxs and keep the previous q->nr_hw_queues.
2819 if (i
!= set
->nr_hw_queues
) {
2820 j
= q
->nr_hw_queues
;
2824 end
= q
->nr_hw_queues
;
2825 q
->nr_hw_queues
= set
->nr_hw_queues
;
2828 for (; j
< end
; j
++) {
2829 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2833 blk_mq_free_map_and_requests(set
, j
);
2834 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2838 mutex_unlock(&q
->sysfs_lock
);
2842 * Maximum number of hardware queues we support. For single sets, we'll never
2843 * have more than the CPUs (software queues). For multiple sets, the tag_set
2844 * user may have set ->nr_hw_queues larger.
2846 static unsigned int nr_hw_queues(struct blk_mq_tag_set
*set
)
2848 if (set
->nr_maps
== 1)
2851 return max(set
->nr_hw_queues
, nr_cpu_ids
);
2854 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2855 struct request_queue
*q
)
2857 /* mark the queue as mq asap */
2858 q
->mq_ops
= set
->ops
;
2860 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2861 blk_mq_poll_stats_bkt
,
2862 BLK_MQ_POLL_STATS_BKTS
, q
);
2866 if (blk_mq_alloc_ctxs(q
))
2869 /* init q->mq_kobj and sw queues' kobjects */
2870 blk_mq_sysfs_init(q
);
2872 q
->nr_queues
= nr_hw_queues(set
);
2873 q
->queue_hw_ctx
= kcalloc_node(q
->nr_queues
, sizeof(*(q
->queue_hw_ctx
)),
2874 GFP_KERNEL
, set
->numa_node
);
2875 if (!q
->queue_hw_ctx
)
2878 INIT_LIST_HEAD(&q
->unused_hctx_list
);
2879 spin_lock_init(&q
->unused_hctx_lock
);
2881 blk_mq_realloc_hw_ctxs(set
, q
);
2882 if (!q
->nr_hw_queues
)
2885 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2886 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2890 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2891 if (set
->nr_maps
> HCTX_TYPE_POLL
&&
2892 set
->map
[HCTX_TYPE_POLL
].nr_queues
)
2893 blk_queue_flag_set(QUEUE_FLAG_POLL
, q
);
2895 q
->sg_reserved_size
= INT_MAX
;
2897 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2898 INIT_LIST_HEAD(&q
->requeue_list
);
2899 spin_lock_init(&q
->requeue_lock
);
2901 blk_queue_make_request(q
, blk_mq_make_request
);
2904 * Do this after blk_queue_make_request() overrides it...
2906 q
->nr_requests
= set
->queue_depth
;
2909 * Default to classic polling
2911 q
->poll_nsec
= BLK_MQ_POLL_CLASSIC
;
2913 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2914 blk_mq_add_queue_tag_set(set
, q
);
2915 blk_mq_map_swqueue(q
);
2917 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2920 ret
= elevator_init_mq(q
);
2922 return ERR_PTR(ret
);
2928 kfree(q
->queue_hw_ctx
);
2930 blk_mq_sysfs_deinit(q
);
2933 return ERR_PTR(-ENOMEM
);
2935 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2937 /* tags can _not_ be used after returning from blk_mq_exit_queue */
2938 void blk_mq_exit_queue(struct request_queue
*q
)
2940 struct blk_mq_tag_set
*set
= q
->tag_set
;
2942 blk_mq_del_queue_tag_set(q
);
2943 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2946 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2950 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2951 if (!__blk_mq_alloc_rq_map(set
, i
))
2958 blk_mq_free_rq_map(set
->tags
[i
]);
2964 * Allocate the request maps associated with this tag_set. Note that this
2965 * may reduce the depth asked for, if memory is tight. set->queue_depth
2966 * will be updated to reflect the allocated depth.
2968 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2973 depth
= set
->queue_depth
;
2975 err
= __blk_mq_alloc_rq_maps(set
);
2979 set
->queue_depth
>>= 1;
2980 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2984 } while (set
->queue_depth
);
2986 if (!set
->queue_depth
|| err
) {
2987 pr_err("blk-mq: failed to allocate request map\n");
2991 if (depth
!= set
->queue_depth
)
2992 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2993 depth
, set
->queue_depth
);
2998 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
3000 if (set
->ops
->map_queues
&& !is_kdump_kernel()) {
3004 * transport .map_queues is usually done in the following
3007 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
3008 * mask = get_cpu_mask(queue)
3009 * for_each_cpu(cpu, mask)
3010 * set->map[x].mq_map[cpu] = queue;
3013 * When we need to remap, the table has to be cleared for
3014 * killing stale mapping since one CPU may not be mapped
3017 for (i
= 0; i
< set
->nr_maps
; i
++)
3018 blk_mq_clear_mq_map(&set
->map
[i
]);
3020 return set
->ops
->map_queues(set
);
3022 BUG_ON(set
->nr_maps
> 1);
3023 return blk_mq_map_queues(&set
->map
[HCTX_TYPE_DEFAULT
]);
3028 * Alloc a tag set to be associated with one or more request queues.
3029 * May fail with EINVAL for various error conditions. May adjust the
3030 * requested depth down, if it's too large. In that case, the set
3031 * value will be stored in set->queue_depth.
3033 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
3037 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
3039 if (!set
->nr_hw_queues
)
3041 if (!set
->queue_depth
)
3043 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
3046 if (!set
->ops
->queue_rq
)
3049 if (!set
->ops
->get_budget
^ !set
->ops
->put_budget
)
3052 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
3053 pr_info("blk-mq: reduced tag depth to %u\n",
3055 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
3060 else if (set
->nr_maps
> HCTX_MAX_TYPES
)
3064 * If a crashdump is active, then we are potentially in a very
3065 * memory constrained environment. Limit us to 1 queue and
3066 * 64 tags to prevent using too much memory.
3068 if (is_kdump_kernel()) {
3069 set
->nr_hw_queues
= 1;
3071 set
->queue_depth
= min(64U, set
->queue_depth
);
3074 * There is no use for more h/w queues than cpus if we just have
3077 if (set
->nr_maps
== 1 && set
->nr_hw_queues
> nr_cpu_ids
)
3078 set
->nr_hw_queues
= nr_cpu_ids
;
3080 set
->tags
= kcalloc_node(nr_hw_queues(set
), sizeof(struct blk_mq_tags
*),
3081 GFP_KERNEL
, set
->numa_node
);
3086 for (i
= 0; i
< set
->nr_maps
; i
++) {
3087 set
->map
[i
].mq_map
= kcalloc_node(nr_cpu_ids
,
3088 sizeof(set
->map
[i
].mq_map
[0]),
3089 GFP_KERNEL
, set
->numa_node
);
3090 if (!set
->map
[i
].mq_map
)
3091 goto out_free_mq_map
;
3092 set
->map
[i
].nr_queues
= is_kdump_kernel() ? 1 : set
->nr_hw_queues
;
3095 ret
= blk_mq_update_queue_map(set
);
3097 goto out_free_mq_map
;
3099 ret
= blk_mq_alloc_rq_maps(set
);
3101 goto out_free_mq_map
;
3103 mutex_init(&set
->tag_list_lock
);
3104 INIT_LIST_HEAD(&set
->tag_list
);
3109 for (i
= 0; i
< set
->nr_maps
; i
++) {
3110 kfree(set
->map
[i
].mq_map
);
3111 set
->map
[i
].mq_map
= NULL
;
3117 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
3119 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
3123 for (i
= 0; i
< nr_hw_queues(set
); i
++)
3124 blk_mq_free_map_and_requests(set
, i
);
3126 for (j
= 0; j
< set
->nr_maps
; j
++) {
3127 kfree(set
->map
[j
].mq_map
);
3128 set
->map
[j
].mq_map
= NULL
;
3134 EXPORT_SYMBOL(blk_mq_free_tag_set
);
3136 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
3138 struct blk_mq_tag_set
*set
= q
->tag_set
;
3139 struct blk_mq_hw_ctx
*hctx
;
3145 if (q
->nr_requests
== nr
)
3148 blk_mq_freeze_queue(q
);
3149 blk_mq_quiesce_queue(q
);
3152 queue_for_each_hw_ctx(q
, hctx
, i
) {
3156 * If we're using an MQ scheduler, just update the scheduler
3157 * queue depth. This is similar to what the old code would do.
3159 if (!hctx
->sched_tags
) {
3160 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
, nr
,
3163 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
3168 if (q
->elevator
&& q
->elevator
->type
->ops
.depth_updated
)
3169 q
->elevator
->type
->ops
.depth_updated(hctx
);
3173 q
->nr_requests
= nr
;
3175 blk_mq_unquiesce_queue(q
);
3176 blk_mq_unfreeze_queue(q
);
3182 * request_queue and elevator_type pair.
3183 * It is just used by __blk_mq_update_nr_hw_queues to cache
3184 * the elevator_type associated with a request_queue.
3186 struct blk_mq_qe_pair
{
3187 struct list_head node
;
3188 struct request_queue
*q
;
3189 struct elevator_type
*type
;
3193 * Cache the elevator_type in qe pair list and switch the
3194 * io scheduler to 'none'
3196 static bool blk_mq_elv_switch_none(struct list_head
*head
,
3197 struct request_queue
*q
)
3199 struct blk_mq_qe_pair
*qe
;
3204 qe
= kmalloc(sizeof(*qe
), GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
);
3208 INIT_LIST_HEAD(&qe
->node
);
3210 qe
->type
= q
->elevator
->type
;
3211 list_add(&qe
->node
, head
);
3213 mutex_lock(&q
->sysfs_lock
);
3215 * After elevator_switch_mq, the previous elevator_queue will be
3216 * released by elevator_release. The reference of the io scheduler
3217 * module get by elevator_get will also be put. So we need to get
3218 * a reference of the io scheduler module here to prevent it to be
3221 __module_get(qe
->type
->elevator_owner
);
3222 elevator_switch_mq(q
, NULL
);
3223 mutex_unlock(&q
->sysfs_lock
);
3228 static void blk_mq_elv_switch_back(struct list_head
*head
,
3229 struct request_queue
*q
)
3231 struct blk_mq_qe_pair
*qe
;
3232 struct elevator_type
*t
= NULL
;
3234 list_for_each_entry(qe
, head
, node
)
3243 list_del(&qe
->node
);
3246 mutex_lock(&q
->sysfs_lock
);
3247 elevator_switch_mq(q
, t
);
3248 mutex_unlock(&q
->sysfs_lock
);
3251 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
3254 struct request_queue
*q
;
3256 int prev_nr_hw_queues
;
3258 lockdep_assert_held(&set
->tag_list_lock
);
3260 if (set
->nr_maps
== 1 && nr_hw_queues
> nr_cpu_ids
)
3261 nr_hw_queues
= nr_cpu_ids
;
3262 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
3265 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3266 blk_mq_freeze_queue(q
);
3268 * Sync with blk_mq_queue_tag_busy_iter.
3272 * Switch IO scheduler to 'none', cleaning up the data associated
3273 * with the previous scheduler. We will switch back once we are done
3274 * updating the new sw to hw queue mappings.
3276 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3277 if (!blk_mq_elv_switch_none(&head
, q
))
3280 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3281 blk_mq_debugfs_unregister_hctxs(q
);
3282 blk_mq_sysfs_unregister(q
);
3285 prev_nr_hw_queues
= set
->nr_hw_queues
;
3286 set
->nr_hw_queues
= nr_hw_queues
;
3287 blk_mq_update_queue_map(set
);
3289 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3290 blk_mq_realloc_hw_ctxs(set
, q
);
3291 if (q
->nr_hw_queues
!= set
->nr_hw_queues
) {
3292 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3293 nr_hw_queues
, prev_nr_hw_queues
);
3294 set
->nr_hw_queues
= prev_nr_hw_queues
;
3295 blk_mq_map_queues(&set
->map
[HCTX_TYPE_DEFAULT
]);
3298 blk_mq_map_swqueue(q
);
3301 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3302 blk_mq_sysfs_register(q
);
3303 blk_mq_debugfs_register_hctxs(q
);
3307 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3308 blk_mq_elv_switch_back(&head
, q
);
3310 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3311 blk_mq_unfreeze_queue(q
);
3314 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
3316 mutex_lock(&set
->tag_list_lock
);
3317 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
3318 mutex_unlock(&set
->tag_list_lock
);
3320 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
3322 /* Enable polling stats and return whether they were already enabled. */
3323 static bool blk_poll_stats_enable(struct request_queue
*q
)
3325 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3326 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS
, q
))
3328 blk_stat_add_callback(q
, q
->poll_cb
);
3332 static void blk_mq_poll_stats_start(struct request_queue
*q
)
3335 * We don't arm the callback if polling stats are not enabled or the
3336 * callback is already active.
3338 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3339 blk_stat_is_active(q
->poll_cb
))
3342 blk_stat_activate_msecs(q
->poll_cb
, 100);
3345 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
3347 struct request_queue
*q
= cb
->data
;
3350 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
3351 if (cb
->stat
[bucket
].nr_samples
)
3352 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
3356 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
3357 struct blk_mq_hw_ctx
*hctx
,
3360 unsigned long ret
= 0;
3364 * If stats collection isn't on, don't sleep but turn it on for
3367 if (!blk_poll_stats_enable(q
))
3371 * As an optimistic guess, use half of the mean service time
3372 * for this type of request. We can (and should) make this smarter.
3373 * For instance, if the completion latencies are tight, we can
3374 * get closer than just half the mean. This is especially
3375 * important on devices where the completion latencies are longer
3376 * than ~10 usec. We do use the stats for the relevant IO size
3377 * if available which does lead to better estimates.
3379 bucket
= blk_mq_poll_stats_bkt(rq
);
3383 if (q
->poll_stat
[bucket
].nr_samples
)
3384 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
3389 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
3390 struct blk_mq_hw_ctx
*hctx
,
3393 struct hrtimer_sleeper hs
;
3394 enum hrtimer_mode mode
;
3398 if (rq
->rq_flags
& RQF_MQ_POLL_SLEPT
)
3402 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3404 * 0: use half of prev avg
3405 * >0: use this specific value
3407 if (q
->poll_nsec
> 0)
3408 nsecs
= q
->poll_nsec
;
3410 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
3415 rq
->rq_flags
|= RQF_MQ_POLL_SLEPT
;
3418 * This will be replaced with the stats tracking code, using
3419 * 'avg_completion_time / 2' as the pre-sleep target.
3423 mode
= HRTIMER_MODE_REL
;
3424 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
3425 hrtimer_set_expires(&hs
.timer
, kt
);
3427 hrtimer_init_sleeper(&hs
, current
);
3429 if (blk_mq_rq_state(rq
) == MQ_RQ_COMPLETE
)
3431 set_current_state(TASK_UNINTERRUPTIBLE
);
3432 hrtimer_start_expires(&hs
.timer
, mode
);
3435 hrtimer_cancel(&hs
.timer
);
3436 mode
= HRTIMER_MODE_ABS
;
3437 } while (hs
.task
&& !signal_pending(current
));
3439 __set_current_state(TASK_RUNNING
);
3440 destroy_hrtimer_on_stack(&hs
.timer
);
3444 static bool blk_mq_poll_hybrid(struct request_queue
*q
,
3445 struct blk_mq_hw_ctx
*hctx
, blk_qc_t cookie
)
3449 if (q
->poll_nsec
== BLK_MQ_POLL_CLASSIC
)
3452 if (!blk_qc_t_is_internal(cookie
))
3453 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
3455 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
3457 * With scheduling, if the request has completed, we'll
3458 * get a NULL return here, as we clear the sched tag when
3459 * that happens. The request still remains valid, like always,
3460 * so we should be safe with just the NULL check.
3466 return blk_mq_poll_hybrid_sleep(q
, hctx
, rq
);
3470 * blk_poll - poll for IO completions
3472 * @cookie: cookie passed back at IO submission time
3473 * @spin: whether to spin for completions
3476 * Poll for completions on the passed in queue. Returns number of
3477 * completed entries found. If @spin is true, then blk_poll will continue
3478 * looping until at least one completion is found, unless the task is
3479 * otherwise marked running (or we need to reschedule).
3481 int blk_poll(struct request_queue
*q
, blk_qc_t cookie
, bool spin
)
3483 struct blk_mq_hw_ctx
*hctx
;
3486 if (!blk_qc_t_valid(cookie
) ||
3487 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
3491 blk_flush_plug_list(current
->plug
, false);
3493 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
3496 * If we sleep, have the caller restart the poll loop to reset
3497 * the state. Like for the other success return cases, the
3498 * caller is responsible for checking if the IO completed. If
3499 * the IO isn't complete, we'll get called again and will go
3500 * straight to the busy poll loop.
3502 if (blk_mq_poll_hybrid(q
, hctx
, cookie
))
3505 hctx
->poll_considered
++;
3507 state
= current
->state
;
3511 hctx
->poll_invoked
++;
3513 ret
= q
->mq_ops
->poll(hctx
);
3515 hctx
->poll_success
++;
3516 __set_current_state(TASK_RUNNING
);
3520 if (signal_pending_state(state
, current
))
3521 __set_current_state(TASK_RUNNING
);
3523 if (current
->state
== TASK_RUNNING
)
3525 if (ret
< 0 || !spin
)
3528 } while (!need_resched());
3530 __set_current_state(TASK_RUNNING
);
3533 EXPORT_SYMBOL_GPL(blk_poll
);
3535 unsigned int blk_mq_rq_cpu(struct request
*rq
)
3537 return rq
->mq_ctx
->cpu
;
3539 EXPORT_SYMBOL(blk_mq_rq_cpu
);
3541 static int __init
blk_mq_init(void)
3543 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
3544 blk_mq_hctx_notify_dead
);
3547 subsys_initcall(blk_mq_init
);