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
)
147 mutex_lock(&q
->mq_freeze_lock
);
148 if (++q
->mq_freeze_depth
== 1) {
149 percpu_ref_kill(&q
->q_usage_counter
);
150 mutex_unlock(&q
->mq_freeze_lock
);
152 blk_mq_run_hw_queues(q
, false);
154 mutex_unlock(&q
->mq_freeze_lock
);
157 EXPORT_SYMBOL_GPL(blk_freeze_queue_start
);
159 void blk_mq_freeze_queue_wait(struct request_queue
*q
)
161 wait_event(q
->mq_freeze_wq
, percpu_ref_is_zero(&q
->q_usage_counter
));
163 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait
);
165 int blk_mq_freeze_queue_wait_timeout(struct request_queue
*q
,
166 unsigned long timeout
)
168 return wait_event_timeout(q
->mq_freeze_wq
,
169 percpu_ref_is_zero(&q
->q_usage_counter
),
172 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout
);
175 * Guarantee no request is in use, so we can change any data structure of
176 * the queue afterward.
178 void blk_freeze_queue(struct request_queue
*q
)
181 * In the !blk_mq case we are only calling this to kill the
182 * q_usage_counter, otherwise this increases the freeze depth
183 * and waits for it to return to zero. For this reason there is
184 * no blk_unfreeze_queue(), and blk_freeze_queue() is not
185 * exported to drivers as the only user for unfreeze is blk_mq.
187 blk_freeze_queue_start(q
);
188 blk_mq_freeze_queue_wait(q
);
191 void blk_mq_freeze_queue(struct request_queue
*q
)
194 * ...just an alias to keep freeze and unfreeze actions balanced
195 * in the blk_mq_* namespace
199 EXPORT_SYMBOL_GPL(blk_mq_freeze_queue
);
201 void blk_mq_unfreeze_queue(struct request_queue
*q
)
203 mutex_lock(&q
->mq_freeze_lock
);
204 q
->mq_freeze_depth
--;
205 WARN_ON_ONCE(q
->mq_freeze_depth
< 0);
206 if (!q
->mq_freeze_depth
) {
207 percpu_ref_resurrect(&q
->q_usage_counter
);
208 wake_up_all(&q
->mq_freeze_wq
);
210 mutex_unlock(&q
->mq_freeze_lock
);
212 EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue
);
215 * FIXME: replace the scsi_internal_device_*block_nowait() calls in the
216 * mpt3sas driver such that this function can be removed.
218 void blk_mq_quiesce_queue_nowait(struct request_queue
*q
)
220 blk_queue_flag_set(QUEUE_FLAG_QUIESCED
, q
);
222 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait
);
225 * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
228 * Note: this function does not prevent that the struct request end_io()
229 * callback function is invoked. Once this function is returned, we make
230 * sure no dispatch can happen until the queue is unquiesced via
231 * blk_mq_unquiesce_queue().
233 void blk_mq_quiesce_queue(struct request_queue
*q
)
235 struct blk_mq_hw_ctx
*hctx
;
239 blk_mq_quiesce_queue_nowait(q
);
241 queue_for_each_hw_ctx(q
, hctx
, i
) {
242 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
243 synchronize_srcu(hctx
->srcu
);
250 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue
);
253 * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
256 * This function recovers queue into the state before quiescing
257 * which is done by blk_mq_quiesce_queue.
259 void blk_mq_unquiesce_queue(struct request_queue
*q
)
261 blk_queue_flag_clear(QUEUE_FLAG_QUIESCED
, q
);
263 /* dispatch requests which are inserted during quiescing */
264 blk_mq_run_hw_queues(q
, true);
266 EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue
);
268 void blk_mq_wake_waiters(struct request_queue
*q
)
270 struct blk_mq_hw_ctx
*hctx
;
273 queue_for_each_hw_ctx(q
, hctx
, i
)
274 if (blk_mq_hw_queue_mapped(hctx
))
275 blk_mq_tag_wakeup_all(hctx
->tags
, true);
278 bool blk_mq_can_queue(struct blk_mq_hw_ctx
*hctx
)
280 return blk_mq_has_free_tags(hctx
->tags
);
282 EXPORT_SYMBOL(blk_mq_can_queue
);
285 * Only need start/end time stamping if we have stats enabled, or using
288 static inline bool blk_mq_need_time_stamp(struct request
*rq
)
290 return (rq
->rq_flags
& RQF_IO_STAT
) || rq
->q
->elevator
;
293 static struct request
*blk_mq_rq_ctx_init(struct blk_mq_alloc_data
*data
,
294 unsigned int tag
, unsigned int op
)
296 struct blk_mq_tags
*tags
= blk_mq_tags_from_data(data
);
297 struct request
*rq
= tags
->static_rqs
[tag
];
298 req_flags_t rq_flags
= 0;
300 if (data
->flags
& BLK_MQ_REQ_INTERNAL
) {
302 rq
->internal_tag
= tag
;
304 if (data
->hctx
->flags
& BLK_MQ_F_TAG_SHARED
) {
305 rq_flags
= RQF_MQ_INFLIGHT
;
306 atomic_inc(&data
->hctx
->nr_active
);
309 rq
->internal_tag
= -1;
310 data
->hctx
->tags
->rqs
[rq
->tag
] = rq
;
313 /* csd/requeue_work/fifo_time is initialized before use */
315 rq
->mq_ctx
= data
->ctx
;
316 rq
->mq_hctx
= data
->hctx
;
317 rq
->rq_flags
= rq_flags
;
319 if (data
->flags
& BLK_MQ_REQ_PREEMPT
)
320 rq
->rq_flags
|= RQF_PREEMPT
;
321 if (blk_queue_io_stat(data
->q
))
322 rq
->rq_flags
|= RQF_IO_STAT
;
323 INIT_LIST_HEAD(&rq
->queuelist
);
324 INIT_HLIST_NODE(&rq
->hash
);
325 RB_CLEAR_NODE(&rq
->rb_node
);
328 if (blk_mq_need_time_stamp(rq
))
329 rq
->start_time_ns
= ktime_get_ns();
331 rq
->start_time_ns
= 0;
332 rq
->io_start_time_ns
= 0;
333 rq
->nr_phys_segments
= 0;
334 #if defined(CONFIG_BLK_DEV_INTEGRITY)
335 rq
->nr_integrity_segments
= 0;
337 /* tag was already set */
339 WRITE_ONCE(rq
->deadline
, 0);
344 rq
->end_io_data
= NULL
;
346 data
->ctx
->rq_dispatched
[op_is_sync(op
)]++;
347 refcount_set(&rq
->ref
, 1);
351 static struct request
*blk_mq_get_request(struct request_queue
*q
,
353 struct blk_mq_alloc_data
*data
)
355 struct elevator_queue
*e
= q
->elevator
;
358 bool clear_ctx_on_error
= false;
360 blk_queue_enter_live(q
);
362 if (likely(!data
->ctx
)) {
363 data
->ctx
= blk_mq_get_ctx(q
);
364 clear_ctx_on_error
= true;
366 if (likely(!data
->hctx
))
367 data
->hctx
= blk_mq_map_queue(q
, data
->cmd_flags
,
369 if (data
->cmd_flags
& REQ_NOWAIT
)
370 data
->flags
|= BLK_MQ_REQ_NOWAIT
;
373 data
->flags
|= BLK_MQ_REQ_INTERNAL
;
376 * Flush requests are special and go directly to the
377 * dispatch list. Don't include reserved tags in the
378 * limiting, as it isn't useful.
380 if (!op_is_flush(data
->cmd_flags
) &&
381 e
->type
->ops
.limit_depth
&&
382 !(data
->flags
& BLK_MQ_REQ_RESERVED
))
383 e
->type
->ops
.limit_depth(data
->cmd_flags
, data
);
385 blk_mq_tag_busy(data
->hctx
);
388 tag
= blk_mq_get_tag(data
);
389 if (tag
== BLK_MQ_TAG_FAIL
) {
390 if (clear_ctx_on_error
)
396 rq
= blk_mq_rq_ctx_init(data
, tag
, data
->cmd_flags
);
397 if (!op_is_flush(data
->cmd_flags
)) {
399 if (e
&& e
->type
->ops
.prepare_request
) {
400 if (e
->type
->icq_cache
)
401 blk_mq_sched_assign_ioc(rq
);
403 e
->type
->ops
.prepare_request(rq
, bio
);
404 rq
->rq_flags
|= RQF_ELVPRIV
;
407 data
->hctx
->queued
++;
411 struct request
*blk_mq_alloc_request(struct request_queue
*q
, unsigned int op
,
412 blk_mq_req_flags_t flags
)
414 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
, .cmd_flags
= op
};
418 ret
= blk_queue_enter(q
, flags
);
422 rq
= blk_mq_get_request(q
, NULL
, &alloc_data
);
426 return ERR_PTR(-EWOULDBLOCK
);
429 rq
->__sector
= (sector_t
) -1;
430 rq
->bio
= rq
->biotail
= NULL
;
433 EXPORT_SYMBOL(blk_mq_alloc_request
);
435 struct request
*blk_mq_alloc_request_hctx(struct request_queue
*q
,
436 unsigned int op
, blk_mq_req_flags_t flags
, unsigned int hctx_idx
)
438 struct blk_mq_alloc_data alloc_data
= { .flags
= flags
, .cmd_flags
= op
};
444 * If the tag allocator sleeps we could get an allocation for a
445 * different hardware context. No need to complicate the low level
446 * allocator for this for the rare use case of a command tied to
449 if (WARN_ON_ONCE(!(flags
& BLK_MQ_REQ_NOWAIT
)))
450 return ERR_PTR(-EINVAL
);
452 if (hctx_idx
>= q
->nr_hw_queues
)
453 return ERR_PTR(-EIO
);
455 ret
= blk_queue_enter(q
, flags
);
460 * Check if the hardware context is actually mapped to anything.
461 * If not tell the caller that it should skip this queue.
463 alloc_data
.hctx
= q
->queue_hw_ctx
[hctx_idx
];
464 if (!blk_mq_hw_queue_mapped(alloc_data
.hctx
)) {
466 return ERR_PTR(-EXDEV
);
468 cpu
= cpumask_first_and(alloc_data
.hctx
->cpumask
, cpu_online_mask
);
469 alloc_data
.ctx
= __blk_mq_get_ctx(q
, cpu
);
471 rq
= blk_mq_get_request(q
, NULL
, &alloc_data
);
475 return ERR_PTR(-EWOULDBLOCK
);
479 EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx
);
481 static void __blk_mq_free_request(struct request
*rq
)
483 struct request_queue
*q
= rq
->q
;
484 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
485 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
486 const int sched_tag
= rq
->internal_tag
;
488 blk_pm_mark_last_busy(rq
);
491 blk_mq_put_tag(hctx
, hctx
->tags
, ctx
, rq
->tag
);
493 blk_mq_put_tag(hctx
, hctx
->sched_tags
, ctx
, sched_tag
);
494 blk_mq_sched_restart(hctx
);
498 void blk_mq_free_request(struct request
*rq
)
500 struct request_queue
*q
= rq
->q
;
501 struct elevator_queue
*e
= q
->elevator
;
502 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
503 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
505 if (rq
->rq_flags
& RQF_ELVPRIV
) {
506 if (e
&& e
->type
->ops
.finish_request
)
507 e
->type
->ops
.finish_request(rq
);
509 put_io_context(rq
->elv
.icq
->ioc
);
514 ctx
->rq_completed
[rq_is_sync(rq
)]++;
515 if (rq
->rq_flags
& RQF_MQ_INFLIGHT
)
516 atomic_dec(&hctx
->nr_active
);
518 if (unlikely(laptop_mode
&& !blk_rq_is_passthrough(rq
)))
519 laptop_io_completion(q
->backing_dev_info
);
523 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
524 if (refcount_dec_and_test(&rq
->ref
))
525 __blk_mq_free_request(rq
);
527 EXPORT_SYMBOL_GPL(blk_mq_free_request
);
529 inline void __blk_mq_end_request(struct request
*rq
, blk_status_t error
)
533 if (blk_mq_need_time_stamp(rq
))
534 now
= ktime_get_ns();
536 if (rq
->rq_flags
& RQF_STATS
) {
537 blk_mq_poll_stats_start(rq
->q
);
538 blk_stat_add(rq
, now
);
541 if (rq
->internal_tag
!= -1)
542 blk_mq_sched_completed_request(rq
, now
);
544 blk_account_io_done(rq
, now
);
547 rq_qos_done(rq
->q
, rq
);
548 rq
->end_io(rq
, error
);
550 blk_mq_free_request(rq
);
553 EXPORT_SYMBOL(__blk_mq_end_request
);
555 void blk_mq_end_request(struct request
*rq
, blk_status_t error
)
557 if (blk_update_request(rq
, error
, blk_rq_bytes(rq
)))
559 __blk_mq_end_request(rq
, error
);
561 EXPORT_SYMBOL(blk_mq_end_request
);
563 static void __blk_mq_complete_request_remote(void *data
)
565 struct request
*rq
= data
;
566 struct request_queue
*q
= rq
->q
;
568 q
->mq_ops
->complete(rq
);
571 static void __blk_mq_complete_request(struct request
*rq
)
573 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
574 struct request_queue
*q
= rq
->q
;
578 WRITE_ONCE(rq
->state
, MQ_RQ_COMPLETE
);
580 * Most of single queue controllers, there is only one irq vector
581 * for handling IO completion, and the only irq's affinity is set
582 * as all possible CPUs. On most of ARCHs, this affinity means the
583 * irq is handled on one specific CPU.
585 * So complete IO reqeust in softirq context in case of single queue
586 * for not degrading IO performance by irqsoff latency.
588 if (q
->nr_hw_queues
== 1) {
589 __blk_complete_request(rq
);
594 * For a polled request, always complete locallly, it's pointless
595 * to redirect the completion.
597 if ((rq
->cmd_flags
& REQ_HIPRI
) ||
598 !test_bit(QUEUE_FLAG_SAME_COMP
, &q
->queue_flags
)) {
599 q
->mq_ops
->complete(rq
);
604 if (!test_bit(QUEUE_FLAG_SAME_FORCE
, &q
->queue_flags
))
605 shared
= cpus_share_cache(cpu
, ctx
->cpu
);
607 if (cpu
!= ctx
->cpu
&& !shared
&& cpu_online(ctx
->cpu
)) {
608 rq
->csd
.func
= __blk_mq_complete_request_remote
;
611 smp_call_function_single_async(ctx
->cpu
, &rq
->csd
);
613 q
->mq_ops
->complete(rq
);
618 static void hctx_unlock(struct blk_mq_hw_ctx
*hctx
, int srcu_idx
)
619 __releases(hctx
->srcu
)
621 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
))
624 srcu_read_unlock(hctx
->srcu
, srcu_idx
);
627 static void hctx_lock(struct blk_mq_hw_ctx
*hctx
, int *srcu_idx
)
628 __acquires(hctx
->srcu
)
630 if (!(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
631 /* shut up gcc false positive */
635 *srcu_idx
= srcu_read_lock(hctx
->srcu
);
639 * blk_mq_complete_request - end I/O on a request
640 * @rq: the request being processed
643 * Ends all I/O on a request. It does not handle partial completions.
644 * The actual completion happens out-of-order, through a IPI handler.
646 bool blk_mq_complete_request(struct request
*rq
)
648 if (unlikely(blk_should_fake_timeout(rq
->q
)))
650 __blk_mq_complete_request(rq
);
653 EXPORT_SYMBOL(blk_mq_complete_request
);
655 void blk_mq_complete_request_sync(struct request
*rq
)
657 WRITE_ONCE(rq
->state
, MQ_RQ_COMPLETE
);
658 rq
->q
->mq_ops
->complete(rq
);
660 EXPORT_SYMBOL_GPL(blk_mq_complete_request_sync
);
662 int blk_mq_request_started(struct request
*rq
)
664 return blk_mq_rq_state(rq
) != MQ_RQ_IDLE
;
666 EXPORT_SYMBOL_GPL(blk_mq_request_started
);
668 void blk_mq_start_request(struct request
*rq
)
670 struct request_queue
*q
= rq
->q
;
672 trace_block_rq_issue(q
, rq
);
674 if (test_bit(QUEUE_FLAG_STATS
, &q
->queue_flags
)) {
675 rq
->io_start_time_ns
= ktime_get_ns();
676 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
677 rq
->throtl_size
= blk_rq_sectors(rq
);
679 rq
->rq_flags
|= RQF_STATS
;
683 WARN_ON_ONCE(blk_mq_rq_state(rq
) != MQ_RQ_IDLE
);
686 WRITE_ONCE(rq
->state
, MQ_RQ_IN_FLIGHT
);
688 if (q
->dma_drain_size
&& blk_rq_bytes(rq
)) {
690 * Make sure space for the drain appears. We know we can do
691 * this because max_hw_segments has been adjusted to be one
692 * fewer than the device can handle.
694 rq
->nr_phys_segments
++;
697 EXPORT_SYMBOL(blk_mq_start_request
);
699 static void __blk_mq_requeue_request(struct request
*rq
)
701 struct request_queue
*q
= rq
->q
;
703 blk_mq_put_driver_tag(rq
);
705 trace_block_rq_requeue(q
, rq
);
706 rq_qos_requeue(q
, rq
);
708 if (blk_mq_request_started(rq
)) {
709 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
710 rq
->rq_flags
&= ~RQF_TIMED_OUT
;
711 if (q
->dma_drain_size
&& blk_rq_bytes(rq
))
712 rq
->nr_phys_segments
--;
716 void blk_mq_requeue_request(struct request
*rq
, bool kick_requeue_list
)
718 __blk_mq_requeue_request(rq
);
720 /* this request will be re-inserted to io scheduler queue */
721 blk_mq_sched_requeue_request(rq
);
723 BUG_ON(!list_empty(&rq
->queuelist
));
724 blk_mq_add_to_requeue_list(rq
, true, kick_requeue_list
);
726 EXPORT_SYMBOL(blk_mq_requeue_request
);
728 static void blk_mq_requeue_work(struct work_struct
*work
)
730 struct request_queue
*q
=
731 container_of(work
, struct request_queue
, requeue_work
.work
);
733 struct request
*rq
, *next
;
735 spin_lock_irq(&q
->requeue_lock
);
736 list_splice_init(&q
->requeue_list
, &rq_list
);
737 spin_unlock_irq(&q
->requeue_lock
);
739 list_for_each_entry_safe(rq
, next
, &rq_list
, queuelist
) {
740 if (!(rq
->rq_flags
& (RQF_SOFTBARRIER
| RQF_DONTPREP
)))
743 rq
->rq_flags
&= ~RQF_SOFTBARRIER
;
744 list_del_init(&rq
->queuelist
);
746 * If RQF_DONTPREP, rq has contained some driver specific
747 * data, so insert it to hctx dispatch list to avoid any
750 if (rq
->rq_flags
& RQF_DONTPREP
)
751 blk_mq_request_bypass_insert(rq
, false);
753 blk_mq_sched_insert_request(rq
, true, false, false);
756 while (!list_empty(&rq_list
)) {
757 rq
= list_entry(rq_list
.next
, struct request
, queuelist
);
758 list_del_init(&rq
->queuelist
);
759 blk_mq_sched_insert_request(rq
, false, false, false);
762 blk_mq_run_hw_queues(q
, false);
765 void blk_mq_add_to_requeue_list(struct request
*rq
, bool at_head
,
766 bool kick_requeue_list
)
768 struct request_queue
*q
= rq
->q
;
772 * We abuse this flag that is otherwise used by the I/O scheduler to
773 * request head insertion from the workqueue.
775 BUG_ON(rq
->rq_flags
& RQF_SOFTBARRIER
);
777 spin_lock_irqsave(&q
->requeue_lock
, flags
);
779 rq
->rq_flags
|= RQF_SOFTBARRIER
;
780 list_add(&rq
->queuelist
, &q
->requeue_list
);
782 list_add_tail(&rq
->queuelist
, &q
->requeue_list
);
784 spin_unlock_irqrestore(&q
->requeue_lock
, flags
);
786 if (kick_requeue_list
)
787 blk_mq_kick_requeue_list(q
);
790 void blk_mq_kick_requeue_list(struct request_queue
*q
)
792 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
, 0);
794 EXPORT_SYMBOL(blk_mq_kick_requeue_list
);
796 void blk_mq_delay_kick_requeue_list(struct request_queue
*q
,
799 kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND
, &q
->requeue_work
,
800 msecs_to_jiffies(msecs
));
802 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list
);
804 struct request
*blk_mq_tag_to_rq(struct blk_mq_tags
*tags
, unsigned int tag
)
806 if (tag
< tags
->nr_tags
) {
807 prefetch(tags
->rqs
[tag
]);
808 return tags
->rqs
[tag
];
813 EXPORT_SYMBOL(blk_mq_tag_to_rq
);
815 static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
816 void *priv
, bool reserved
)
819 * If we find a request that is inflight and the queue matches,
820 * we know the queue is busy. Return false to stop the iteration.
822 if (rq
->state
== MQ_RQ_IN_FLIGHT
&& rq
->q
== hctx
->queue
) {
832 bool blk_mq_queue_inflight(struct request_queue
*q
)
836 blk_mq_queue_tag_busy_iter(q
, blk_mq_rq_inflight
, &busy
);
839 EXPORT_SYMBOL_GPL(blk_mq_queue_inflight
);
841 static void blk_mq_rq_timed_out(struct request
*req
, bool reserved
)
843 req
->rq_flags
|= RQF_TIMED_OUT
;
844 if (req
->q
->mq_ops
->timeout
) {
845 enum blk_eh_timer_return ret
;
847 ret
= req
->q
->mq_ops
->timeout(req
, reserved
);
848 if (ret
== BLK_EH_DONE
)
850 WARN_ON_ONCE(ret
!= BLK_EH_RESET_TIMER
);
856 static bool blk_mq_req_expired(struct request
*rq
, unsigned long *next
)
858 unsigned long deadline
;
860 if (blk_mq_rq_state(rq
) != MQ_RQ_IN_FLIGHT
)
862 if (rq
->rq_flags
& RQF_TIMED_OUT
)
865 deadline
= READ_ONCE(rq
->deadline
);
866 if (time_after_eq(jiffies
, deadline
))
871 else if (time_after(*next
, deadline
))
876 static bool blk_mq_check_expired(struct blk_mq_hw_ctx
*hctx
,
877 struct request
*rq
, void *priv
, bool reserved
)
879 unsigned long *next
= priv
;
882 * Just do a quick check if it is expired before locking the request in
883 * so we're not unnecessarilly synchronizing across CPUs.
885 if (!blk_mq_req_expired(rq
, next
))
889 * We have reason to believe the request may be expired. Take a
890 * reference on the request to lock this request lifetime into its
891 * currently allocated context to prevent it from being reallocated in
892 * the event the completion by-passes this timeout handler.
894 * If the reference was already released, then the driver beat the
895 * timeout handler to posting a natural completion.
897 if (!refcount_inc_not_zero(&rq
->ref
))
901 * The request is now locked and cannot be reallocated underneath the
902 * timeout handler's processing. Re-verify this exact request is truly
903 * expired; if it is not expired, then the request was completed and
904 * reallocated as a new request.
906 if (blk_mq_req_expired(rq
, next
))
907 blk_mq_rq_timed_out(rq
, reserved
);
908 if (refcount_dec_and_test(&rq
->ref
))
909 __blk_mq_free_request(rq
);
914 static void blk_mq_timeout_work(struct work_struct
*work
)
916 struct request_queue
*q
=
917 container_of(work
, struct request_queue
, timeout_work
);
918 unsigned long next
= 0;
919 struct blk_mq_hw_ctx
*hctx
;
922 /* A deadlock might occur if a request is stuck requiring a
923 * timeout at the same time a queue freeze is waiting
924 * completion, since the timeout code would not be able to
925 * acquire the queue reference here.
927 * That's why we don't use blk_queue_enter here; instead, we use
928 * percpu_ref_tryget directly, because we need to be able to
929 * obtain a reference even in the short window between the queue
930 * starting to freeze, by dropping the first reference in
931 * blk_freeze_queue_start, and the moment the last request is
932 * consumed, marked by the instant q_usage_counter reaches
935 if (!percpu_ref_tryget(&q
->q_usage_counter
))
938 blk_mq_queue_tag_busy_iter(q
, blk_mq_check_expired
, &next
);
941 mod_timer(&q
->timeout
, next
);
944 * Request timeouts are handled as a forward rolling timer. If
945 * we end up here it means that no requests are pending and
946 * also that no request has been pending for a while. Mark
949 queue_for_each_hw_ctx(q
, hctx
, i
) {
950 /* the hctx may be unmapped, so check it here */
951 if (blk_mq_hw_queue_mapped(hctx
))
952 blk_mq_tag_idle(hctx
);
958 struct flush_busy_ctx_data
{
959 struct blk_mq_hw_ctx
*hctx
;
960 struct list_head
*list
;
963 static bool flush_busy_ctx(struct sbitmap
*sb
, unsigned int bitnr
, void *data
)
965 struct flush_busy_ctx_data
*flush_data
= data
;
966 struct blk_mq_hw_ctx
*hctx
= flush_data
->hctx
;
967 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
968 enum hctx_type type
= hctx
->type
;
970 spin_lock(&ctx
->lock
);
971 list_splice_tail_init(&ctx
->rq_lists
[type
], flush_data
->list
);
972 sbitmap_clear_bit(sb
, bitnr
);
973 spin_unlock(&ctx
->lock
);
978 * Process software queues that have been marked busy, splicing them
979 * to the for-dispatch
981 void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx
*hctx
, struct list_head
*list
)
983 struct flush_busy_ctx_data data
= {
988 sbitmap_for_each_set(&hctx
->ctx_map
, flush_busy_ctx
, &data
);
990 EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs
);
992 struct dispatch_rq_data
{
993 struct blk_mq_hw_ctx
*hctx
;
997 static bool dispatch_rq_from_ctx(struct sbitmap
*sb
, unsigned int bitnr
,
1000 struct dispatch_rq_data
*dispatch_data
= data
;
1001 struct blk_mq_hw_ctx
*hctx
= dispatch_data
->hctx
;
1002 struct blk_mq_ctx
*ctx
= hctx
->ctxs
[bitnr
];
1003 enum hctx_type type
= hctx
->type
;
1005 spin_lock(&ctx
->lock
);
1006 if (!list_empty(&ctx
->rq_lists
[type
])) {
1007 dispatch_data
->rq
= list_entry_rq(ctx
->rq_lists
[type
].next
);
1008 list_del_init(&dispatch_data
->rq
->queuelist
);
1009 if (list_empty(&ctx
->rq_lists
[type
]))
1010 sbitmap_clear_bit(sb
, bitnr
);
1012 spin_unlock(&ctx
->lock
);
1014 return !dispatch_data
->rq
;
1017 struct request
*blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx
*hctx
,
1018 struct blk_mq_ctx
*start
)
1020 unsigned off
= start
? start
->index_hw
[hctx
->type
] : 0;
1021 struct dispatch_rq_data data
= {
1026 __sbitmap_for_each_set(&hctx
->ctx_map
, off
,
1027 dispatch_rq_from_ctx
, &data
);
1032 static inline unsigned int queued_to_index(unsigned int queued
)
1037 return min(BLK_MQ_MAX_DISPATCH_ORDER
- 1, ilog2(queued
) + 1);
1040 bool blk_mq_get_driver_tag(struct request
*rq
)
1042 struct blk_mq_alloc_data data
= {
1044 .hctx
= rq
->mq_hctx
,
1045 .flags
= BLK_MQ_REQ_NOWAIT
,
1046 .cmd_flags
= rq
->cmd_flags
,
1053 if (blk_mq_tag_is_reserved(data
.hctx
->sched_tags
, rq
->internal_tag
))
1054 data
.flags
|= BLK_MQ_REQ_RESERVED
;
1056 shared
= blk_mq_tag_busy(data
.hctx
);
1057 rq
->tag
= blk_mq_get_tag(&data
);
1060 rq
->rq_flags
|= RQF_MQ_INFLIGHT
;
1061 atomic_inc(&data
.hctx
->nr_active
);
1063 data
.hctx
->tags
->rqs
[rq
->tag
] = rq
;
1067 return rq
->tag
!= -1;
1070 static int blk_mq_dispatch_wake(wait_queue_entry_t
*wait
, unsigned mode
,
1071 int flags
, void *key
)
1073 struct blk_mq_hw_ctx
*hctx
;
1075 hctx
= container_of(wait
, struct blk_mq_hw_ctx
, dispatch_wait
);
1077 spin_lock(&hctx
->dispatch_wait_lock
);
1078 if (!list_empty(&wait
->entry
)) {
1079 struct sbitmap_queue
*sbq
;
1081 list_del_init(&wait
->entry
);
1082 sbq
= &hctx
->tags
->bitmap_tags
;
1083 atomic_dec(&sbq
->ws_active
);
1085 spin_unlock(&hctx
->dispatch_wait_lock
);
1087 blk_mq_run_hw_queue(hctx
, true);
1092 * Mark us waiting for a tag. For shared tags, this involves hooking us into
1093 * the tag wakeups. For non-shared tags, we can simply mark us needing a
1094 * restart. For both cases, take care to check the condition again after
1095 * marking us as waiting.
1097 static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx
*hctx
,
1100 struct sbitmap_queue
*sbq
= &hctx
->tags
->bitmap_tags
;
1101 struct wait_queue_head
*wq
;
1102 wait_queue_entry_t
*wait
;
1105 if (!(hctx
->flags
& BLK_MQ_F_TAG_SHARED
)) {
1106 blk_mq_sched_mark_restart_hctx(hctx
);
1109 * It's possible that a tag was freed in the window between the
1110 * allocation failure and adding the hardware queue to the wait
1113 * Don't clear RESTART here, someone else could have set it.
1114 * At most this will cost an extra queue run.
1116 return blk_mq_get_driver_tag(rq
);
1119 wait
= &hctx
->dispatch_wait
;
1120 if (!list_empty_careful(&wait
->entry
))
1123 wq
= &bt_wait_ptr(sbq
, hctx
)->wait
;
1125 spin_lock_irq(&wq
->lock
);
1126 spin_lock(&hctx
->dispatch_wait_lock
);
1127 if (!list_empty(&wait
->entry
)) {
1128 spin_unlock(&hctx
->dispatch_wait_lock
);
1129 spin_unlock_irq(&wq
->lock
);
1133 atomic_inc(&sbq
->ws_active
);
1134 wait
->flags
&= ~WQ_FLAG_EXCLUSIVE
;
1135 __add_wait_queue(wq
, wait
);
1138 * It's possible that a tag was freed in the window between the
1139 * allocation failure and adding the hardware queue to the wait
1142 ret
= blk_mq_get_driver_tag(rq
);
1144 spin_unlock(&hctx
->dispatch_wait_lock
);
1145 spin_unlock_irq(&wq
->lock
);
1150 * We got a tag, remove ourselves from the wait queue to ensure
1151 * someone else gets the wakeup.
1153 list_del_init(&wait
->entry
);
1154 atomic_dec(&sbq
->ws_active
);
1155 spin_unlock(&hctx
->dispatch_wait_lock
);
1156 spin_unlock_irq(&wq
->lock
);
1161 #define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
1162 #define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
1164 * Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
1165 * - EWMA is one simple way to compute running average value
1166 * - weight(7/8 and 1/8) is applied so that it can decrease exponentially
1167 * - take 4 as factor for avoiding to get too small(0) result, and this
1168 * factor doesn't matter because EWMA decreases exponentially
1170 static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx
*hctx
, bool busy
)
1174 if (hctx
->queue
->elevator
)
1177 ewma
= hctx
->dispatch_busy
;
1182 ewma
*= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
- 1;
1184 ewma
+= 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR
;
1185 ewma
/= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT
;
1187 hctx
->dispatch_busy
= ewma
;
1190 #define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
1193 * Returns true if we did some work AND can potentially do more.
1195 bool blk_mq_dispatch_rq_list(struct request_queue
*q
, struct list_head
*list
,
1198 struct blk_mq_hw_ctx
*hctx
;
1199 struct request
*rq
, *nxt
;
1200 bool no_tag
= false;
1202 blk_status_t ret
= BLK_STS_OK
;
1204 if (list_empty(list
))
1207 WARN_ON(!list_is_singular(list
) && got_budget
);
1210 * Now process all the entries, sending them to the driver.
1212 errors
= queued
= 0;
1214 struct blk_mq_queue_data bd
;
1216 rq
= list_first_entry(list
, struct request
, queuelist
);
1219 if (!got_budget
&& !blk_mq_get_dispatch_budget(hctx
))
1222 if (!blk_mq_get_driver_tag(rq
)) {
1224 * The initial allocation attempt failed, so we need to
1225 * rerun the hardware queue when a tag is freed. The
1226 * waitqueue takes care of that. If the queue is run
1227 * before we add this entry back on the dispatch list,
1228 * we'll re-run it below.
1230 if (!blk_mq_mark_tag_wait(hctx
, rq
)) {
1231 blk_mq_put_dispatch_budget(hctx
);
1233 * For non-shared tags, the RESTART check
1236 if (hctx
->flags
& BLK_MQ_F_TAG_SHARED
)
1242 list_del_init(&rq
->queuelist
);
1247 * Flag last if we have no more requests, or if we have more
1248 * but can't assign a driver tag to it.
1250 if (list_empty(list
))
1253 nxt
= list_first_entry(list
, struct request
, queuelist
);
1254 bd
.last
= !blk_mq_get_driver_tag(nxt
);
1257 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1258 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
) {
1260 * If an I/O scheduler has been configured and we got a
1261 * driver tag for the next request already, free it
1264 if (!list_empty(list
)) {
1265 nxt
= list_first_entry(list
, struct request
, queuelist
);
1266 blk_mq_put_driver_tag(nxt
);
1268 list_add(&rq
->queuelist
, list
);
1269 __blk_mq_requeue_request(rq
);
1273 if (unlikely(ret
!= BLK_STS_OK
)) {
1275 blk_mq_end_request(rq
, BLK_STS_IOERR
);
1280 } while (!list_empty(list
));
1282 hctx
->dispatched
[queued_to_index(queued
)]++;
1285 * Any items that need requeuing? Stuff them into hctx->dispatch,
1286 * that is where we will continue on next queue run.
1288 if (!list_empty(list
)) {
1292 * If we didn't flush the entire list, we could have told
1293 * the driver there was more coming, but that turned out to
1296 if (q
->mq_ops
->commit_rqs
)
1297 q
->mq_ops
->commit_rqs(hctx
);
1299 spin_lock(&hctx
->lock
);
1300 list_splice_init(list
, &hctx
->dispatch
);
1301 spin_unlock(&hctx
->lock
);
1304 * If SCHED_RESTART was set by the caller of this function and
1305 * it is no longer set that means that it was cleared by another
1306 * thread and hence that a queue rerun is needed.
1308 * If 'no_tag' is set, that means that we failed getting
1309 * a driver tag with an I/O scheduler attached. If our dispatch
1310 * waitqueue is no longer active, ensure that we run the queue
1311 * AFTER adding our entries back to the list.
1313 * If no I/O scheduler has been configured it is possible that
1314 * the hardware queue got stopped and restarted before requests
1315 * were pushed back onto the dispatch list. Rerun the queue to
1316 * avoid starvation. Notes:
1317 * - blk_mq_run_hw_queue() checks whether or not a queue has
1318 * been stopped before rerunning a queue.
1319 * - Some but not all block drivers stop a queue before
1320 * returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
1323 * If driver returns BLK_STS_RESOURCE and SCHED_RESTART
1324 * bit is set, run queue after a delay to avoid IO stalls
1325 * that could otherwise occur if the queue is idle.
1327 needs_restart
= blk_mq_sched_needs_restart(hctx
);
1328 if (!needs_restart
||
1329 (no_tag
&& list_empty_careful(&hctx
->dispatch_wait
.entry
)))
1330 blk_mq_run_hw_queue(hctx
, true);
1331 else if (needs_restart
&& (ret
== BLK_STS_RESOURCE
))
1332 blk_mq_delay_run_hw_queue(hctx
, BLK_MQ_RESOURCE_DELAY
);
1334 blk_mq_update_dispatch_busy(hctx
, true);
1337 blk_mq_update_dispatch_busy(hctx
, false);
1340 * If the host/device is unable to accept more work, inform the
1343 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
)
1346 return (queued
+ errors
) != 0;
1349 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1354 * We should be running this queue from one of the CPUs that
1357 * There are at least two related races now between setting
1358 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
1359 * __blk_mq_run_hw_queue():
1361 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
1362 * but later it becomes online, then this warning is harmless
1365 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
1366 * but later it becomes offline, then the warning can't be
1367 * triggered, and we depend on blk-mq timeout handler to
1368 * handle dispatched requests to this hctx
1370 if (!cpumask_test_cpu(raw_smp_processor_id(), hctx
->cpumask
) &&
1371 cpu_online(hctx
->next_cpu
)) {
1372 printk(KERN_WARNING
"run queue from wrong CPU %d, hctx %s\n",
1373 raw_smp_processor_id(),
1374 cpumask_empty(hctx
->cpumask
) ? "inactive": "active");
1379 * We can't run the queue inline with ints disabled. Ensure that
1380 * we catch bad users of this early.
1382 WARN_ON_ONCE(in_interrupt());
1384 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1386 hctx_lock(hctx
, &srcu_idx
);
1387 blk_mq_sched_dispatch_requests(hctx
);
1388 hctx_unlock(hctx
, srcu_idx
);
1391 static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx
*hctx
)
1393 int cpu
= cpumask_first_and(hctx
->cpumask
, cpu_online_mask
);
1395 if (cpu
>= nr_cpu_ids
)
1396 cpu
= cpumask_first(hctx
->cpumask
);
1401 * It'd be great if the workqueue API had a way to pass
1402 * in a mask and had some smarts for more clever placement.
1403 * For now we just round-robin here, switching for every
1404 * BLK_MQ_CPU_WORK_BATCH queued items.
1406 static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx
*hctx
)
1409 int next_cpu
= hctx
->next_cpu
;
1411 if (hctx
->queue
->nr_hw_queues
== 1)
1412 return WORK_CPU_UNBOUND
;
1414 if (--hctx
->next_cpu_batch
<= 0) {
1416 next_cpu
= cpumask_next_and(next_cpu
, hctx
->cpumask
,
1418 if (next_cpu
>= nr_cpu_ids
)
1419 next_cpu
= blk_mq_first_mapped_cpu(hctx
);
1420 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
1424 * Do unbound schedule if we can't find a online CPU for this hctx,
1425 * and it should only happen in the path of handling CPU DEAD.
1427 if (!cpu_online(next_cpu
)) {
1434 * Make sure to re-select CPU next time once after CPUs
1435 * in hctx->cpumask become online again.
1437 hctx
->next_cpu
= next_cpu
;
1438 hctx
->next_cpu_batch
= 1;
1439 return WORK_CPU_UNBOUND
;
1442 hctx
->next_cpu
= next_cpu
;
1446 static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
,
1447 unsigned long msecs
)
1449 if (unlikely(blk_mq_hctx_stopped(hctx
)))
1452 if (!async
&& !(hctx
->flags
& BLK_MQ_F_BLOCKING
)) {
1453 int cpu
= get_cpu();
1454 if (cpumask_test_cpu(cpu
, hctx
->cpumask
)) {
1455 __blk_mq_run_hw_queue(hctx
);
1463 kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx
), &hctx
->run_work
,
1464 msecs_to_jiffies(msecs
));
1467 void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, unsigned long msecs
)
1469 __blk_mq_delay_run_hw_queue(hctx
, true, msecs
);
1471 EXPORT_SYMBOL(blk_mq_delay_run_hw_queue
);
1473 bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1479 * When queue is quiesced, we may be switching io scheduler, or
1480 * updating nr_hw_queues, or other things, and we can't run queue
1481 * any more, even __blk_mq_hctx_has_pending() can't be called safely.
1483 * And queue will be rerun in blk_mq_unquiesce_queue() if it is
1486 hctx_lock(hctx
, &srcu_idx
);
1487 need_run
= !blk_queue_quiesced(hctx
->queue
) &&
1488 blk_mq_hctx_has_pending(hctx
);
1489 hctx_unlock(hctx
, srcu_idx
);
1492 __blk_mq_delay_run_hw_queue(hctx
, async
, 0);
1498 EXPORT_SYMBOL(blk_mq_run_hw_queue
);
1500 void blk_mq_run_hw_queues(struct request_queue
*q
, bool async
)
1502 struct blk_mq_hw_ctx
*hctx
;
1505 queue_for_each_hw_ctx(q
, hctx
, i
) {
1506 if (blk_mq_hctx_stopped(hctx
))
1509 blk_mq_run_hw_queue(hctx
, async
);
1512 EXPORT_SYMBOL(blk_mq_run_hw_queues
);
1515 * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
1516 * @q: request queue.
1518 * The caller is responsible for serializing this function against
1519 * blk_mq_{start,stop}_hw_queue().
1521 bool blk_mq_queue_stopped(struct request_queue
*q
)
1523 struct blk_mq_hw_ctx
*hctx
;
1526 queue_for_each_hw_ctx(q
, hctx
, i
)
1527 if (blk_mq_hctx_stopped(hctx
))
1532 EXPORT_SYMBOL(blk_mq_queue_stopped
);
1535 * This function is often used for pausing .queue_rq() by driver when
1536 * there isn't enough resource or some conditions aren't satisfied, and
1537 * BLK_STS_RESOURCE is usually returned.
1539 * We do not guarantee that dispatch can be drained or blocked
1540 * after blk_mq_stop_hw_queue() returns. Please use
1541 * blk_mq_quiesce_queue() for that requirement.
1543 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1545 cancel_delayed_work(&hctx
->run_work
);
1547 set_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1549 EXPORT_SYMBOL(blk_mq_stop_hw_queue
);
1552 * This function is often used for pausing .queue_rq() by driver when
1553 * there isn't enough resource or some conditions aren't satisfied, and
1554 * BLK_STS_RESOURCE is usually returned.
1556 * We do not guarantee that dispatch can be drained or blocked
1557 * after blk_mq_stop_hw_queues() returns. Please use
1558 * blk_mq_quiesce_queue() for that requirement.
1560 void blk_mq_stop_hw_queues(struct request_queue
*q
)
1562 struct blk_mq_hw_ctx
*hctx
;
1565 queue_for_each_hw_ctx(q
, hctx
, i
)
1566 blk_mq_stop_hw_queue(hctx
);
1568 EXPORT_SYMBOL(blk_mq_stop_hw_queues
);
1570 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx
*hctx
)
1572 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1574 blk_mq_run_hw_queue(hctx
, false);
1576 EXPORT_SYMBOL(blk_mq_start_hw_queue
);
1578 void blk_mq_start_hw_queues(struct request_queue
*q
)
1580 struct blk_mq_hw_ctx
*hctx
;
1583 queue_for_each_hw_ctx(q
, hctx
, i
)
1584 blk_mq_start_hw_queue(hctx
);
1586 EXPORT_SYMBOL(blk_mq_start_hw_queues
);
1588 void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx
*hctx
, bool async
)
1590 if (!blk_mq_hctx_stopped(hctx
))
1593 clear_bit(BLK_MQ_S_STOPPED
, &hctx
->state
);
1594 blk_mq_run_hw_queue(hctx
, async
);
1596 EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue
);
1598 void blk_mq_start_stopped_hw_queues(struct request_queue
*q
, bool async
)
1600 struct blk_mq_hw_ctx
*hctx
;
1603 queue_for_each_hw_ctx(q
, hctx
, i
)
1604 blk_mq_start_stopped_hw_queue(hctx
, async
);
1606 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues
);
1608 static void blk_mq_run_work_fn(struct work_struct
*work
)
1610 struct blk_mq_hw_ctx
*hctx
;
1612 hctx
= container_of(work
, struct blk_mq_hw_ctx
, run_work
.work
);
1615 * If we are stopped, don't run the queue.
1617 if (test_bit(BLK_MQ_S_STOPPED
, &hctx
->state
))
1620 __blk_mq_run_hw_queue(hctx
);
1623 static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx
*hctx
,
1627 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1628 enum hctx_type type
= hctx
->type
;
1630 lockdep_assert_held(&ctx
->lock
);
1632 trace_block_rq_insert(hctx
->queue
, rq
);
1635 list_add(&rq
->queuelist
, &ctx
->rq_lists
[type
]);
1637 list_add_tail(&rq
->queuelist
, &ctx
->rq_lists
[type
]);
1640 void __blk_mq_insert_request(struct blk_mq_hw_ctx
*hctx
, struct request
*rq
,
1643 struct blk_mq_ctx
*ctx
= rq
->mq_ctx
;
1645 lockdep_assert_held(&ctx
->lock
);
1647 __blk_mq_insert_req_list(hctx
, rq
, at_head
);
1648 blk_mq_hctx_mark_pending(hctx
, ctx
);
1652 * Should only be used carefully, when the caller knows we want to
1653 * bypass a potential IO scheduler on the target device.
1655 void blk_mq_request_bypass_insert(struct request
*rq
, bool run_queue
)
1657 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1659 spin_lock(&hctx
->lock
);
1660 list_add_tail(&rq
->queuelist
, &hctx
->dispatch
);
1661 spin_unlock(&hctx
->lock
);
1664 blk_mq_run_hw_queue(hctx
, false);
1667 void blk_mq_insert_requests(struct blk_mq_hw_ctx
*hctx
, struct blk_mq_ctx
*ctx
,
1668 struct list_head
*list
)
1672 enum hctx_type type
= hctx
->type
;
1675 * preemption doesn't flush plug list, so it's possible ctx->cpu is
1678 list_for_each_entry(rq
, list
, queuelist
) {
1679 BUG_ON(rq
->mq_ctx
!= ctx
);
1680 trace_block_rq_insert(hctx
->queue
, rq
);
1683 spin_lock(&ctx
->lock
);
1684 list_splice_tail_init(list
, &ctx
->rq_lists
[type
]);
1685 blk_mq_hctx_mark_pending(hctx
, ctx
);
1686 spin_unlock(&ctx
->lock
);
1689 static int plug_rq_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
1691 struct request
*rqa
= container_of(a
, struct request
, queuelist
);
1692 struct request
*rqb
= container_of(b
, struct request
, queuelist
);
1694 if (rqa
->mq_ctx
< rqb
->mq_ctx
)
1696 else if (rqa
->mq_ctx
> rqb
->mq_ctx
)
1698 else if (rqa
->mq_hctx
< rqb
->mq_hctx
)
1700 else if (rqa
->mq_hctx
> rqb
->mq_hctx
)
1703 return blk_rq_pos(rqa
) > blk_rq_pos(rqb
);
1706 void blk_mq_flush_plug_list(struct blk_plug
*plug
, bool from_schedule
)
1708 struct blk_mq_hw_ctx
*this_hctx
;
1709 struct blk_mq_ctx
*this_ctx
;
1710 struct request_queue
*this_q
;
1716 list_splice_init(&plug
->mq_list
, &list
);
1718 if (plug
->rq_count
> 2 && plug
->multiple_queues
)
1719 list_sort(NULL
, &list
, plug_rq_cmp
);
1728 while (!list_empty(&list
)) {
1729 rq
= list_entry_rq(list
.next
);
1730 list_del_init(&rq
->queuelist
);
1732 if (rq
->mq_hctx
!= this_hctx
|| rq
->mq_ctx
!= this_ctx
) {
1734 trace_block_unplug(this_q
, depth
, !from_schedule
);
1735 blk_mq_sched_insert_requests(this_hctx
, this_ctx
,
1741 this_ctx
= rq
->mq_ctx
;
1742 this_hctx
= rq
->mq_hctx
;
1747 list_add_tail(&rq
->queuelist
, &rq_list
);
1751 * If 'this_hctx' is set, we know we have entries to complete
1752 * on 'rq_list'. Do those.
1755 trace_block_unplug(this_q
, depth
, !from_schedule
);
1756 blk_mq_sched_insert_requests(this_hctx
, this_ctx
, &rq_list
,
1761 static void blk_mq_bio_to_request(struct request
*rq
, struct bio
*bio
,
1762 unsigned int nr_segs
)
1764 if (bio
->bi_opf
& REQ_RAHEAD
)
1765 rq
->cmd_flags
|= REQ_FAILFAST_MASK
;
1767 rq
->__sector
= bio
->bi_iter
.bi_sector
;
1768 rq
->write_hint
= bio
->bi_write_hint
;
1769 blk_rq_bio_prep(rq
, bio
, nr_segs
);
1771 blk_account_io_start(rq
, true);
1774 static blk_status_t
__blk_mq_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1776 blk_qc_t
*cookie
, bool last
)
1778 struct request_queue
*q
= rq
->q
;
1779 struct blk_mq_queue_data bd
= {
1783 blk_qc_t new_cookie
;
1786 new_cookie
= request_to_qc_t(hctx
, rq
);
1789 * For OK queue, we are done. For error, caller may kill it.
1790 * Any other error (busy), just add it to our list as we
1791 * previously would have done.
1793 ret
= q
->mq_ops
->queue_rq(hctx
, &bd
);
1796 blk_mq_update_dispatch_busy(hctx
, false);
1797 *cookie
= new_cookie
;
1799 case BLK_STS_RESOURCE
:
1800 case BLK_STS_DEV_RESOURCE
:
1801 blk_mq_update_dispatch_busy(hctx
, true);
1802 __blk_mq_requeue_request(rq
);
1805 blk_mq_update_dispatch_busy(hctx
, false);
1806 *cookie
= BLK_QC_T_NONE
;
1813 static blk_status_t
__blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1816 bool bypass_insert
, bool last
)
1818 struct request_queue
*q
= rq
->q
;
1819 bool run_queue
= true;
1822 * RCU or SRCU read lock is needed before checking quiesced flag.
1824 * When queue is stopped or quiesced, ignore 'bypass_insert' from
1825 * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
1826 * and avoid driver to try to dispatch again.
1828 if (blk_mq_hctx_stopped(hctx
) || blk_queue_quiesced(q
)) {
1830 bypass_insert
= false;
1834 if (q
->elevator
&& !bypass_insert
)
1837 if (!blk_mq_get_dispatch_budget(hctx
))
1840 if (!blk_mq_get_driver_tag(rq
)) {
1841 blk_mq_put_dispatch_budget(hctx
);
1845 return __blk_mq_issue_directly(hctx
, rq
, cookie
, last
);
1848 return BLK_STS_RESOURCE
;
1850 blk_mq_request_bypass_insert(rq
, run_queue
);
1854 static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx
*hctx
,
1855 struct request
*rq
, blk_qc_t
*cookie
)
1860 might_sleep_if(hctx
->flags
& BLK_MQ_F_BLOCKING
);
1862 hctx_lock(hctx
, &srcu_idx
);
1864 ret
= __blk_mq_try_issue_directly(hctx
, rq
, cookie
, false, true);
1865 if (ret
== BLK_STS_RESOURCE
|| ret
== BLK_STS_DEV_RESOURCE
)
1866 blk_mq_request_bypass_insert(rq
, true);
1867 else if (ret
!= BLK_STS_OK
)
1868 blk_mq_end_request(rq
, ret
);
1870 hctx_unlock(hctx
, srcu_idx
);
1873 blk_status_t
blk_mq_request_issue_directly(struct request
*rq
, bool last
)
1877 blk_qc_t unused_cookie
;
1878 struct blk_mq_hw_ctx
*hctx
= rq
->mq_hctx
;
1880 hctx_lock(hctx
, &srcu_idx
);
1881 ret
= __blk_mq_try_issue_directly(hctx
, rq
, &unused_cookie
, true, last
);
1882 hctx_unlock(hctx
, srcu_idx
);
1887 void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx
*hctx
,
1888 struct list_head
*list
)
1890 while (!list_empty(list
)) {
1892 struct request
*rq
= list_first_entry(list
, struct request
,
1895 list_del_init(&rq
->queuelist
);
1896 ret
= blk_mq_request_issue_directly(rq
, list_empty(list
));
1897 if (ret
!= BLK_STS_OK
) {
1898 if (ret
== BLK_STS_RESOURCE
||
1899 ret
== BLK_STS_DEV_RESOURCE
) {
1900 blk_mq_request_bypass_insert(rq
,
1904 blk_mq_end_request(rq
, ret
);
1909 * If we didn't flush the entire list, we could have told
1910 * the driver there was more coming, but that turned out to
1913 if (!list_empty(list
) && hctx
->queue
->mq_ops
->commit_rqs
)
1914 hctx
->queue
->mq_ops
->commit_rqs(hctx
);
1917 static void blk_add_rq_to_plug(struct blk_plug
*plug
, struct request
*rq
)
1919 list_add_tail(&rq
->queuelist
, &plug
->mq_list
);
1921 if (!plug
->multiple_queues
&& !list_is_singular(&plug
->mq_list
)) {
1922 struct request
*tmp
;
1924 tmp
= list_first_entry(&plug
->mq_list
, struct request
,
1926 if (tmp
->q
!= rq
->q
)
1927 plug
->multiple_queues
= true;
1931 static blk_qc_t
blk_mq_make_request(struct request_queue
*q
, struct bio
*bio
)
1933 const int is_sync
= op_is_sync(bio
->bi_opf
);
1934 const int is_flush_fua
= op_is_flush(bio
->bi_opf
);
1935 struct blk_mq_alloc_data data
= { .flags
= 0};
1937 struct blk_plug
*plug
;
1938 struct request
*same_queue_rq
= NULL
;
1939 unsigned int nr_segs
;
1942 blk_queue_bounce(q
, &bio
);
1943 __blk_queue_split(q
, &bio
, &nr_segs
);
1945 if (!bio_integrity_prep(bio
))
1946 return BLK_QC_T_NONE
;
1948 if (!is_flush_fua
&& !blk_queue_nomerges(q
) &&
1949 blk_attempt_plug_merge(q
, bio
, nr_segs
, &same_queue_rq
))
1950 return BLK_QC_T_NONE
;
1952 if (blk_mq_sched_bio_merge(q
, bio
, nr_segs
))
1953 return BLK_QC_T_NONE
;
1955 rq_qos_throttle(q
, bio
);
1957 data
.cmd_flags
= bio
->bi_opf
;
1958 rq
= blk_mq_get_request(q
, bio
, &data
);
1959 if (unlikely(!rq
)) {
1960 rq_qos_cleanup(q
, bio
);
1962 cookie
= BLK_QC_T_NONE
;
1963 if (bio
->bi_opf
& REQ_NOWAIT_INLINE
)
1964 cookie
= BLK_QC_T_EAGAIN
;
1965 else if (bio
->bi_opf
& REQ_NOWAIT
)
1966 bio_wouldblock_error(bio
);
1970 trace_block_getrq(q
, bio
, bio
->bi_opf
);
1972 rq_qos_track(q
, rq
, bio
);
1974 cookie
= request_to_qc_t(data
.hctx
, rq
);
1976 blk_mq_bio_to_request(rq
, bio
, nr_segs
);
1978 plug
= blk_mq_plug(q
, bio
);
1979 if (unlikely(is_flush_fua
)) {
1980 /* bypass scheduler for flush rq */
1981 blk_insert_flush(rq
);
1982 blk_mq_run_hw_queue(data
.hctx
, true);
1983 } else if (plug
&& (q
->nr_hw_queues
== 1 || q
->mq_ops
->commit_rqs
)) {
1985 * Use plugging if we have a ->commit_rqs() hook as well, as
1986 * we know the driver uses bd->last in a smart fashion.
1988 unsigned int request_count
= plug
->rq_count
;
1989 struct request
*last
= NULL
;
1992 trace_block_plug(q
);
1994 last
= list_entry_rq(plug
->mq_list
.prev
);
1996 if (request_count
>= BLK_MAX_REQUEST_COUNT
|| (last
&&
1997 blk_rq_bytes(last
) >= BLK_PLUG_FLUSH_SIZE
)) {
1998 blk_flush_plug_list(plug
, false);
1999 trace_block_plug(q
);
2002 blk_add_rq_to_plug(plug
, rq
);
2003 } else if (plug
&& !blk_queue_nomerges(q
)) {
2005 * We do limited plugging. If the bio can be merged, do that.
2006 * Otherwise the existing request in the plug list will be
2007 * issued. So the plug list will have one request at most
2008 * The plug list might get flushed before this. If that happens,
2009 * the plug list is empty, and same_queue_rq is invalid.
2011 if (list_empty(&plug
->mq_list
))
2012 same_queue_rq
= NULL
;
2013 if (same_queue_rq
) {
2014 list_del_init(&same_queue_rq
->queuelist
);
2017 blk_add_rq_to_plug(plug
, rq
);
2018 trace_block_plug(q
);
2020 if (same_queue_rq
) {
2021 data
.hctx
= same_queue_rq
->mq_hctx
;
2022 trace_block_unplug(q
, 1, true);
2023 blk_mq_try_issue_directly(data
.hctx
, same_queue_rq
,
2026 } else if ((q
->nr_hw_queues
> 1 && is_sync
) || (!q
->elevator
&&
2027 !data
.hctx
->dispatch_busy
)) {
2028 blk_mq_try_issue_directly(data
.hctx
, rq
, &cookie
);
2030 blk_mq_sched_insert_request(rq
, false, true, true);
2036 void blk_mq_free_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2037 unsigned int hctx_idx
)
2041 if (tags
->rqs
&& set
->ops
->exit_request
) {
2044 for (i
= 0; i
< tags
->nr_tags
; i
++) {
2045 struct request
*rq
= tags
->static_rqs
[i
];
2049 set
->ops
->exit_request(set
, rq
, hctx_idx
);
2050 tags
->static_rqs
[i
] = NULL
;
2054 while (!list_empty(&tags
->page_list
)) {
2055 page
= list_first_entry(&tags
->page_list
, struct page
, lru
);
2056 list_del_init(&page
->lru
);
2058 * Remove kmemleak object previously allocated in
2059 * blk_mq_alloc_rqs().
2061 kmemleak_free(page_address(page
));
2062 __free_pages(page
, page
->private);
2066 void blk_mq_free_rq_map(struct blk_mq_tags
*tags
)
2070 kfree(tags
->static_rqs
);
2071 tags
->static_rqs
= NULL
;
2073 blk_mq_free_tags(tags
);
2076 struct blk_mq_tags
*blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
,
2077 unsigned int hctx_idx
,
2078 unsigned int nr_tags
,
2079 unsigned int reserved_tags
)
2081 struct blk_mq_tags
*tags
;
2084 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], hctx_idx
);
2085 if (node
== NUMA_NO_NODE
)
2086 node
= set
->numa_node
;
2088 tags
= blk_mq_init_tags(nr_tags
, reserved_tags
, node
,
2089 BLK_MQ_FLAG_TO_ALLOC_POLICY(set
->flags
));
2093 tags
->rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2094 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2097 blk_mq_free_tags(tags
);
2101 tags
->static_rqs
= kcalloc_node(nr_tags
, sizeof(struct request
*),
2102 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
,
2104 if (!tags
->static_rqs
) {
2106 blk_mq_free_tags(tags
);
2113 static size_t order_to_size(unsigned int order
)
2115 return (size_t)PAGE_SIZE
<< order
;
2118 static int blk_mq_init_request(struct blk_mq_tag_set
*set
, struct request
*rq
,
2119 unsigned int hctx_idx
, int node
)
2123 if (set
->ops
->init_request
) {
2124 ret
= set
->ops
->init_request(set
, rq
, hctx_idx
, node
);
2129 WRITE_ONCE(rq
->state
, MQ_RQ_IDLE
);
2133 int blk_mq_alloc_rqs(struct blk_mq_tag_set
*set
, struct blk_mq_tags
*tags
,
2134 unsigned int hctx_idx
, unsigned int depth
)
2136 unsigned int i
, j
, entries_per_page
, max_order
= 4;
2137 size_t rq_size
, left
;
2140 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], hctx_idx
);
2141 if (node
== NUMA_NO_NODE
)
2142 node
= set
->numa_node
;
2144 INIT_LIST_HEAD(&tags
->page_list
);
2147 * rq_size is the size of the request plus driver payload, rounded
2148 * to the cacheline size
2150 rq_size
= round_up(sizeof(struct request
) + set
->cmd_size
,
2152 left
= rq_size
* depth
;
2154 for (i
= 0; i
< depth
; ) {
2155 int this_order
= max_order
;
2160 while (this_order
&& left
< order_to_size(this_order
- 1))
2164 page
= alloc_pages_node(node
,
2165 GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
| __GFP_ZERO
,
2171 if (order_to_size(this_order
) < rq_size
)
2178 page
->private = this_order
;
2179 list_add_tail(&page
->lru
, &tags
->page_list
);
2181 p
= page_address(page
);
2183 * Allow kmemleak to scan these pages as they contain pointers
2184 * to additional allocations like via ops->init_request().
2186 kmemleak_alloc(p
, order_to_size(this_order
), 1, GFP_NOIO
);
2187 entries_per_page
= order_to_size(this_order
) / rq_size
;
2188 to_do
= min(entries_per_page
, depth
- i
);
2189 left
-= to_do
* rq_size
;
2190 for (j
= 0; j
< to_do
; j
++) {
2191 struct request
*rq
= p
;
2193 tags
->static_rqs
[i
] = rq
;
2194 if (blk_mq_init_request(set
, rq
, hctx_idx
, node
)) {
2195 tags
->static_rqs
[i
] = NULL
;
2206 blk_mq_free_rqs(set
, tags
, hctx_idx
);
2211 * 'cpu' is going away. splice any existing rq_list entries from this
2212 * software queue to the hw queue dispatch list, and ensure that it
2215 static int blk_mq_hctx_notify_dead(unsigned int cpu
, struct hlist_node
*node
)
2217 struct blk_mq_hw_ctx
*hctx
;
2218 struct blk_mq_ctx
*ctx
;
2220 enum hctx_type type
;
2222 hctx
= hlist_entry_safe(node
, struct blk_mq_hw_ctx
, cpuhp_dead
);
2223 ctx
= __blk_mq_get_ctx(hctx
->queue
, cpu
);
2226 spin_lock(&ctx
->lock
);
2227 if (!list_empty(&ctx
->rq_lists
[type
])) {
2228 list_splice_init(&ctx
->rq_lists
[type
], &tmp
);
2229 blk_mq_hctx_clear_pending(hctx
, ctx
);
2231 spin_unlock(&ctx
->lock
);
2233 if (list_empty(&tmp
))
2236 spin_lock(&hctx
->lock
);
2237 list_splice_tail_init(&tmp
, &hctx
->dispatch
);
2238 spin_unlock(&hctx
->lock
);
2240 blk_mq_run_hw_queue(hctx
, true);
2244 static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx
*hctx
)
2246 cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD
,
2250 /* hctx->ctxs will be freed in queue's release handler */
2251 static void blk_mq_exit_hctx(struct request_queue
*q
,
2252 struct blk_mq_tag_set
*set
,
2253 struct blk_mq_hw_ctx
*hctx
, unsigned int hctx_idx
)
2255 if (blk_mq_hw_queue_mapped(hctx
))
2256 blk_mq_tag_idle(hctx
);
2258 if (set
->ops
->exit_request
)
2259 set
->ops
->exit_request(set
, hctx
->fq
->flush_rq
, hctx_idx
);
2261 if (set
->ops
->exit_hctx
)
2262 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2264 blk_mq_remove_cpuhp(hctx
);
2266 spin_lock(&q
->unused_hctx_lock
);
2267 list_add(&hctx
->hctx_list
, &q
->unused_hctx_list
);
2268 spin_unlock(&q
->unused_hctx_lock
);
2271 static void blk_mq_exit_hw_queues(struct request_queue
*q
,
2272 struct blk_mq_tag_set
*set
, int nr_queue
)
2274 struct blk_mq_hw_ctx
*hctx
;
2277 queue_for_each_hw_ctx(q
, hctx
, i
) {
2280 blk_mq_debugfs_unregister_hctx(hctx
);
2281 blk_mq_exit_hctx(q
, set
, hctx
, i
);
2285 static int blk_mq_hw_ctx_size(struct blk_mq_tag_set
*tag_set
)
2287 int hw_ctx_size
= sizeof(struct blk_mq_hw_ctx
);
2289 BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx
, srcu
),
2290 __alignof__(struct blk_mq_hw_ctx
)) !=
2291 sizeof(struct blk_mq_hw_ctx
));
2293 if (tag_set
->flags
& BLK_MQ_F_BLOCKING
)
2294 hw_ctx_size
+= sizeof(struct srcu_struct
);
2299 static int blk_mq_init_hctx(struct request_queue
*q
,
2300 struct blk_mq_tag_set
*set
,
2301 struct blk_mq_hw_ctx
*hctx
, unsigned hctx_idx
)
2303 hctx
->queue_num
= hctx_idx
;
2305 cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD
, &hctx
->cpuhp_dead
);
2307 hctx
->tags
= set
->tags
[hctx_idx
];
2309 if (set
->ops
->init_hctx
&&
2310 set
->ops
->init_hctx(hctx
, set
->driver_data
, hctx_idx
))
2311 goto unregister_cpu_notifier
;
2313 if (blk_mq_init_request(set
, hctx
->fq
->flush_rq
, hctx_idx
,
2319 if (set
->ops
->exit_hctx
)
2320 set
->ops
->exit_hctx(hctx
, hctx_idx
);
2321 unregister_cpu_notifier
:
2322 blk_mq_remove_cpuhp(hctx
);
2326 static struct blk_mq_hw_ctx
*
2327 blk_mq_alloc_hctx(struct request_queue
*q
, struct blk_mq_tag_set
*set
,
2330 struct blk_mq_hw_ctx
*hctx
;
2331 gfp_t gfp
= GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
;
2333 hctx
= kzalloc_node(blk_mq_hw_ctx_size(set
), gfp
, node
);
2335 goto fail_alloc_hctx
;
2337 if (!zalloc_cpumask_var_node(&hctx
->cpumask
, gfp
, node
))
2340 atomic_set(&hctx
->nr_active
, 0);
2341 if (node
== NUMA_NO_NODE
)
2342 node
= set
->numa_node
;
2343 hctx
->numa_node
= node
;
2345 INIT_DELAYED_WORK(&hctx
->run_work
, blk_mq_run_work_fn
);
2346 spin_lock_init(&hctx
->lock
);
2347 INIT_LIST_HEAD(&hctx
->dispatch
);
2349 hctx
->flags
= set
->flags
& ~BLK_MQ_F_TAG_SHARED
;
2351 INIT_LIST_HEAD(&hctx
->hctx_list
);
2354 * Allocate space for all possible cpus to avoid allocation at
2357 hctx
->ctxs
= kmalloc_array_node(nr_cpu_ids
, sizeof(void *),
2362 if (sbitmap_init_node(&hctx
->ctx_map
, nr_cpu_ids
, ilog2(8),
2367 spin_lock_init(&hctx
->dispatch_wait_lock
);
2368 init_waitqueue_func_entry(&hctx
->dispatch_wait
, blk_mq_dispatch_wake
);
2369 INIT_LIST_HEAD(&hctx
->dispatch_wait
.entry
);
2371 hctx
->fq
= blk_alloc_flush_queue(q
, hctx
->numa_node
, set
->cmd_size
,
2376 if (hctx
->flags
& BLK_MQ_F_BLOCKING
)
2377 init_srcu_struct(hctx
->srcu
);
2378 blk_mq_hctx_kobj_init(hctx
);
2383 sbitmap_free(&hctx
->ctx_map
);
2387 free_cpumask_var(hctx
->cpumask
);
2394 static void blk_mq_init_cpu_queues(struct request_queue
*q
,
2395 unsigned int nr_hw_queues
)
2397 struct blk_mq_tag_set
*set
= q
->tag_set
;
2400 for_each_possible_cpu(i
) {
2401 struct blk_mq_ctx
*__ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2402 struct blk_mq_hw_ctx
*hctx
;
2406 spin_lock_init(&__ctx
->lock
);
2407 for (k
= HCTX_TYPE_DEFAULT
; k
< HCTX_MAX_TYPES
; k
++)
2408 INIT_LIST_HEAD(&__ctx
->rq_lists
[k
]);
2413 * Set local node, IFF we have more than one hw queue. If
2414 * not, we remain on the home node of the device
2416 for (j
= 0; j
< set
->nr_maps
; j
++) {
2417 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2418 if (nr_hw_queues
> 1 && hctx
->numa_node
== NUMA_NO_NODE
)
2419 hctx
->numa_node
= local_memory_node(cpu_to_node(i
));
2424 static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set
*set
, int hctx_idx
)
2428 set
->tags
[hctx_idx
] = blk_mq_alloc_rq_map(set
, hctx_idx
,
2429 set
->queue_depth
, set
->reserved_tags
);
2430 if (!set
->tags
[hctx_idx
])
2433 ret
= blk_mq_alloc_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
,
2438 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2439 set
->tags
[hctx_idx
] = NULL
;
2443 static void blk_mq_free_map_and_requests(struct blk_mq_tag_set
*set
,
2444 unsigned int hctx_idx
)
2446 if (set
->tags
&& set
->tags
[hctx_idx
]) {
2447 blk_mq_free_rqs(set
, set
->tags
[hctx_idx
], hctx_idx
);
2448 blk_mq_free_rq_map(set
->tags
[hctx_idx
]);
2449 set
->tags
[hctx_idx
] = NULL
;
2453 static void blk_mq_map_swqueue(struct request_queue
*q
)
2455 unsigned int i
, j
, hctx_idx
;
2456 struct blk_mq_hw_ctx
*hctx
;
2457 struct blk_mq_ctx
*ctx
;
2458 struct blk_mq_tag_set
*set
= q
->tag_set
;
2461 * Avoid others reading imcomplete hctx->cpumask through sysfs
2463 mutex_lock(&q
->sysfs_lock
);
2465 queue_for_each_hw_ctx(q
, hctx
, i
) {
2466 cpumask_clear(hctx
->cpumask
);
2468 hctx
->dispatch_from
= NULL
;
2472 * Map software to hardware queues.
2474 * If the cpu isn't present, the cpu is mapped to first hctx.
2476 for_each_possible_cpu(i
) {
2477 hctx_idx
= set
->map
[HCTX_TYPE_DEFAULT
].mq_map
[i
];
2478 /* unmapped hw queue can be remapped after CPU topo changed */
2479 if (!set
->tags
[hctx_idx
] &&
2480 !__blk_mq_alloc_rq_map(set
, hctx_idx
)) {
2482 * If tags initialization fail for some hctx,
2483 * that hctx won't be brought online. In this
2484 * case, remap the current ctx to hctx[0] which
2485 * is guaranteed to always have tags allocated
2487 set
->map
[HCTX_TYPE_DEFAULT
].mq_map
[i
] = 0;
2490 ctx
= per_cpu_ptr(q
->queue_ctx
, i
);
2491 for (j
= 0; j
< set
->nr_maps
; j
++) {
2492 if (!set
->map
[j
].nr_queues
) {
2493 ctx
->hctxs
[j
] = blk_mq_map_queue_type(q
,
2494 HCTX_TYPE_DEFAULT
, i
);
2498 hctx
= blk_mq_map_queue_type(q
, j
, i
);
2499 ctx
->hctxs
[j
] = hctx
;
2501 * If the CPU is already set in the mask, then we've
2502 * mapped this one already. This can happen if
2503 * devices share queues across queue maps.
2505 if (cpumask_test_cpu(i
, hctx
->cpumask
))
2508 cpumask_set_cpu(i
, hctx
->cpumask
);
2510 ctx
->index_hw
[hctx
->type
] = hctx
->nr_ctx
;
2511 hctx
->ctxs
[hctx
->nr_ctx
++] = ctx
;
2514 * If the nr_ctx type overflows, we have exceeded the
2515 * amount of sw queues we can support.
2517 BUG_ON(!hctx
->nr_ctx
);
2520 for (; j
< HCTX_MAX_TYPES
; j
++)
2521 ctx
->hctxs
[j
] = blk_mq_map_queue_type(q
,
2522 HCTX_TYPE_DEFAULT
, i
);
2525 mutex_unlock(&q
->sysfs_lock
);
2527 queue_for_each_hw_ctx(q
, hctx
, i
) {
2529 * If no software queues are mapped to this hardware queue,
2530 * disable it and free the request entries.
2532 if (!hctx
->nr_ctx
) {
2533 /* Never unmap queue 0. We need it as a
2534 * fallback in case of a new remap fails
2537 if (i
&& set
->tags
[i
])
2538 blk_mq_free_map_and_requests(set
, i
);
2544 hctx
->tags
= set
->tags
[i
];
2545 WARN_ON(!hctx
->tags
);
2548 * Set the map size to the number of mapped software queues.
2549 * This is more accurate and more efficient than looping
2550 * over all possibly mapped software queues.
2552 sbitmap_resize(&hctx
->ctx_map
, hctx
->nr_ctx
);
2555 * Initialize batch roundrobin counts
2557 hctx
->next_cpu
= blk_mq_first_mapped_cpu(hctx
);
2558 hctx
->next_cpu_batch
= BLK_MQ_CPU_WORK_BATCH
;
2563 * Caller needs to ensure that we're either frozen/quiesced, or that
2564 * the queue isn't live yet.
2566 static void queue_set_hctx_shared(struct request_queue
*q
, bool shared
)
2568 struct blk_mq_hw_ctx
*hctx
;
2571 queue_for_each_hw_ctx(q
, hctx
, i
) {
2573 hctx
->flags
|= BLK_MQ_F_TAG_SHARED
;
2575 hctx
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2579 static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set
*set
,
2582 struct request_queue
*q
;
2584 lockdep_assert_held(&set
->tag_list_lock
);
2586 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
2587 blk_mq_freeze_queue(q
);
2588 queue_set_hctx_shared(q
, shared
);
2589 blk_mq_unfreeze_queue(q
);
2593 static void blk_mq_del_queue_tag_set(struct request_queue
*q
)
2595 struct blk_mq_tag_set
*set
= q
->tag_set
;
2597 mutex_lock(&set
->tag_list_lock
);
2598 list_del_rcu(&q
->tag_set_list
);
2599 if (list_is_singular(&set
->tag_list
)) {
2600 /* just transitioned to unshared */
2601 set
->flags
&= ~BLK_MQ_F_TAG_SHARED
;
2602 /* update existing queue */
2603 blk_mq_update_tag_set_depth(set
, false);
2605 mutex_unlock(&set
->tag_list_lock
);
2606 INIT_LIST_HEAD(&q
->tag_set_list
);
2609 static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set
*set
,
2610 struct request_queue
*q
)
2612 mutex_lock(&set
->tag_list_lock
);
2615 * Check to see if we're transitioning to shared (from 1 to 2 queues).
2617 if (!list_empty(&set
->tag_list
) &&
2618 !(set
->flags
& BLK_MQ_F_TAG_SHARED
)) {
2619 set
->flags
|= BLK_MQ_F_TAG_SHARED
;
2620 /* update existing queue */
2621 blk_mq_update_tag_set_depth(set
, true);
2623 if (set
->flags
& BLK_MQ_F_TAG_SHARED
)
2624 queue_set_hctx_shared(q
, true);
2625 list_add_tail_rcu(&q
->tag_set_list
, &set
->tag_list
);
2627 mutex_unlock(&set
->tag_list_lock
);
2630 /* All allocations will be freed in release handler of q->mq_kobj */
2631 static int blk_mq_alloc_ctxs(struct request_queue
*q
)
2633 struct blk_mq_ctxs
*ctxs
;
2636 ctxs
= kzalloc(sizeof(*ctxs
), GFP_KERNEL
);
2640 ctxs
->queue_ctx
= alloc_percpu(struct blk_mq_ctx
);
2641 if (!ctxs
->queue_ctx
)
2644 for_each_possible_cpu(cpu
) {
2645 struct blk_mq_ctx
*ctx
= per_cpu_ptr(ctxs
->queue_ctx
, cpu
);
2649 q
->mq_kobj
= &ctxs
->kobj
;
2650 q
->queue_ctx
= ctxs
->queue_ctx
;
2659 * It is the actual release handler for mq, but we do it from
2660 * request queue's release handler for avoiding use-after-free
2661 * and headache because q->mq_kobj shouldn't have been introduced,
2662 * but we can't group ctx/kctx kobj without it.
2664 void blk_mq_release(struct request_queue
*q
)
2666 struct blk_mq_hw_ctx
*hctx
, *next
;
2669 queue_for_each_hw_ctx(q
, hctx
, i
)
2670 WARN_ON_ONCE(hctx
&& list_empty(&hctx
->hctx_list
));
2672 /* all hctx are in .unused_hctx_list now */
2673 list_for_each_entry_safe(hctx
, next
, &q
->unused_hctx_list
, hctx_list
) {
2674 list_del_init(&hctx
->hctx_list
);
2675 kobject_put(&hctx
->kobj
);
2678 kfree(q
->queue_hw_ctx
);
2681 * release .mq_kobj and sw queue's kobject now because
2682 * both share lifetime with request queue.
2684 blk_mq_sysfs_deinit(q
);
2687 struct request_queue
*blk_mq_init_queue(struct blk_mq_tag_set
*set
)
2689 struct request_queue
*uninit_q
, *q
;
2691 uninit_q
= blk_alloc_queue_node(GFP_KERNEL
, set
->numa_node
);
2693 return ERR_PTR(-ENOMEM
);
2695 q
= blk_mq_init_allocated_queue(set
, uninit_q
);
2697 blk_cleanup_queue(uninit_q
);
2701 EXPORT_SYMBOL(blk_mq_init_queue
);
2704 * Helper for setting up a queue with mq ops, given queue depth, and
2705 * the passed in mq ops flags.
2707 struct request_queue
*blk_mq_init_sq_queue(struct blk_mq_tag_set
*set
,
2708 const struct blk_mq_ops
*ops
,
2709 unsigned int queue_depth
,
2710 unsigned int set_flags
)
2712 struct request_queue
*q
;
2715 memset(set
, 0, sizeof(*set
));
2717 set
->nr_hw_queues
= 1;
2719 set
->queue_depth
= queue_depth
;
2720 set
->numa_node
= NUMA_NO_NODE
;
2721 set
->flags
= set_flags
;
2723 ret
= blk_mq_alloc_tag_set(set
);
2725 return ERR_PTR(ret
);
2727 q
= blk_mq_init_queue(set
);
2729 blk_mq_free_tag_set(set
);
2735 EXPORT_SYMBOL(blk_mq_init_sq_queue
);
2737 static struct blk_mq_hw_ctx
*blk_mq_alloc_and_init_hctx(
2738 struct blk_mq_tag_set
*set
, struct request_queue
*q
,
2739 int hctx_idx
, int node
)
2741 struct blk_mq_hw_ctx
*hctx
= NULL
, *tmp
;
2743 /* reuse dead hctx first */
2744 spin_lock(&q
->unused_hctx_lock
);
2745 list_for_each_entry(tmp
, &q
->unused_hctx_list
, hctx_list
) {
2746 if (tmp
->numa_node
== node
) {
2752 list_del_init(&hctx
->hctx_list
);
2753 spin_unlock(&q
->unused_hctx_lock
);
2756 hctx
= blk_mq_alloc_hctx(q
, set
, node
);
2760 if (blk_mq_init_hctx(q
, set
, hctx
, hctx_idx
))
2766 kobject_put(&hctx
->kobj
);
2771 static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set
*set
,
2772 struct request_queue
*q
)
2775 struct blk_mq_hw_ctx
**hctxs
= q
->queue_hw_ctx
;
2777 /* protect against switching io scheduler */
2778 mutex_lock(&q
->sysfs_lock
);
2779 for (i
= 0; i
< set
->nr_hw_queues
; i
++) {
2781 struct blk_mq_hw_ctx
*hctx
;
2783 node
= blk_mq_hw_queue_to_node(&set
->map
[HCTX_TYPE_DEFAULT
], i
);
2785 * If the hw queue has been mapped to another numa node,
2786 * we need to realloc the hctx. If allocation fails, fallback
2787 * to use the previous one.
2789 if (hctxs
[i
] && (hctxs
[i
]->numa_node
== node
))
2792 hctx
= blk_mq_alloc_and_init_hctx(set
, q
, i
, node
);
2795 blk_mq_exit_hctx(q
, set
, hctxs
[i
], i
);
2799 pr_warn("Allocate new hctx on node %d fails,\
2800 fallback to previous one on node %d\n",
2801 node
, hctxs
[i
]->numa_node
);
2807 * Increasing nr_hw_queues fails. Free the newly allocated
2808 * hctxs and keep the previous q->nr_hw_queues.
2810 if (i
!= set
->nr_hw_queues
) {
2811 j
= q
->nr_hw_queues
;
2815 end
= q
->nr_hw_queues
;
2816 q
->nr_hw_queues
= set
->nr_hw_queues
;
2819 for (; j
< end
; j
++) {
2820 struct blk_mq_hw_ctx
*hctx
= hctxs
[j
];
2824 blk_mq_free_map_and_requests(set
, j
);
2825 blk_mq_exit_hctx(q
, set
, hctx
, j
);
2829 mutex_unlock(&q
->sysfs_lock
);
2833 * Maximum number of hardware queues we support. For single sets, we'll never
2834 * have more than the CPUs (software queues). For multiple sets, the tag_set
2835 * user may have set ->nr_hw_queues larger.
2837 static unsigned int nr_hw_queues(struct blk_mq_tag_set
*set
)
2839 if (set
->nr_maps
== 1)
2842 return max(set
->nr_hw_queues
, nr_cpu_ids
);
2845 struct request_queue
*blk_mq_init_allocated_queue(struct blk_mq_tag_set
*set
,
2846 struct request_queue
*q
)
2848 /* mark the queue as mq asap */
2849 q
->mq_ops
= set
->ops
;
2851 q
->poll_cb
= blk_stat_alloc_callback(blk_mq_poll_stats_fn
,
2852 blk_mq_poll_stats_bkt
,
2853 BLK_MQ_POLL_STATS_BKTS
, q
);
2857 if (blk_mq_alloc_ctxs(q
))
2860 /* init q->mq_kobj and sw queues' kobjects */
2861 blk_mq_sysfs_init(q
);
2863 q
->nr_queues
= nr_hw_queues(set
);
2864 q
->queue_hw_ctx
= kcalloc_node(q
->nr_queues
, sizeof(*(q
->queue_hw_ctx
)),
2865 GFP_KERNEL
, set
->numa_node
);
2866 if (!q
->queue_hw_ctx
)
2869 INIT_LIST_HEAD(&q
->unused_hctx_list
);
2870 spin_lock_init(&q
->unused_hctx_lock
);
2872 blk_mq_realloc_hw_ctxs(set
, q
);
2873 if (!q
->nr_hw_queues
)
2876 INIT_WORK(&q
->timeout_work
, blk_mq_timeout_work
);
2877 blk_queue_rq_timeout(q
, set
->timeout
? set
->timeout
: 30 * HZ
);
2881 q
->queue_flags
|= QUEUE_FLAG_MQ_DEFAULT
;
2882 if (set
->nr_maps
> HCTX_TYPE_POLL
&&
2883 set
->map
[HCTX_TYPE_POLL
].nr_queues
)
2884 blk_queue_flag_set(QUEUE_FLAG_POLL
, q
);
2886 q
->sg_reserved_size
= INT_MAX
;
2888 INIT_DELAYED_WORK(&q
->requeue_work
, blk_mq_requeue_work
);
2889 INIT_LIST_HEAD(&q
->requeue_list
);
2890 spin_lock_init(&q
->requeue_lock
);
2892 blk_queue_make_request(q
, blk_mq_make_request
);
2895 * Do this after blk_queue_make_request() overrides it...
2897 q
->nr_requests
= set
->queue_depth
;
2900 * Default to classic polling
2902 q
->poll_nsec
= BLK_MQ_POLL_CLASSIC
;
2904 blk_mq_init_cpu_queues(q
, set
->nr_hw_queues
);
2905 blk_mq_add_queue_tag_set(set
, q
);
2906 blk_mq_map_swqueue(q
);
2908 if (!(set
->flags
& BLK_MQ_F_NO_SCHED
)) {
2911 ret
= elevator_init_mq(q
);
2913 return ERR_PTR(ret
);
2919 kfree(q
->queue_hw_ctx
);
2921 blk_mq_sysfs_deinit(q
);
2923 blk_stat_free_callback(q
->poll_cb
);
2927 return ERR_PTR(-ENOMEM
);
2929 EXPORT_SYMBOL(blk_mq_init_allocated_queue
);
2931 /* tags can _not_ be used after returning from blk_mq_exit_queue */
2932 void blk_mq_exit_queue(struct request_queue
*q
)
2934 struct blk_mq_tag_set
*set
= q
->tag_set
;
2936 blk_mq_del_queue_tag_set(q
);
2937 blk_mq_exit_hw_queues(q
, set
, set
->nr_hw_queues
);
2940 static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2944 for (i
= 0; i
< set
->nr_hw_queues
; i
++)
2945 if (!__blk_mq_alloc_rq_map(set
, i
))
2952 blk_mq_free_rq_map(set
->tags
[i
]);
2958 * Allocate the request maps associated with this tag_set. Note that this
2959 * may reduce the depth asked for, if memory is tight. set->queue_depth
2960 * will be updated to reflect the allocated depth.
2962 static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set
*set
)
2967 depth
= set
->queue_depth
;
2969 err
= __blk_mq_alloc_rq_maps(set
);
2973 set
->queue_depth
>>= 1;
2974 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
) {
2978 } while (set
->queue_depth
);
2980 if (!set
->queue_depth
|| err
) {
2981 pr_err("blk-mq: failed to allocate request map\n");
2985 if (depth
!= set
->queue_depth
)
2986 pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
2987 depth
, set
->queue_depth
);
2992 static int blk_mq_update_queue_map(struct blk_mq_tag_set
*set
)
2994 if (set
->ops
->map_queues
&& !is_kdump_kernel()) {
2998 * transport .map_queues is usually done in the following
3001 * for (queue = 0; queue < set->nr_hw_queues; queue++) {
3002 * mask = get_cpu_mask(queue)
3003 * for_each_cpu(cpu, mask)
3004 * set->map[x].mq_map[cpu] = queue;
3007 * When we need to remap, the table has to be cleared for
3008 * killing stale mapping since one CPU may not be mapped
3011 for (i
= 0; i
< set
->nr_maps
; i
++)
3012 blk_mq_clear_mq_map(&set
->map
[i
]);
3014 return set
->ops
->map_queues(set
);
3016 BUG_ON(set
->nr_maps
> 1);
3017 return blk_mq_map_queues(&set
->map
[HCTX_TYPE_DEFAULT
]);
3022 * Alloc a tag set to be associated with one or more request queues.
3023 * May fail with EINVAL for various error conditions. May adjust the
3024 * requested depth down, if it's too large. In that case, the set
3025 * value will be stored in set->queue_depth.
3027 int blk_mq_alloc_tag_set(struct blk_mq_tag_set
*set
)
3031 BUILD_BUG_ON(BLK_MQ_MAX_DEPTH
> 1 << BLK_MQ_UNIQUE_TAG_BITS
);
3033 if (!set
->nr_hw_queues
)
3035 if (!set
->queue_depth
)
3037 if (set
->queue_depth
< set
->reserved_tags
+ BLK_MQ_TAG_MIN
)
3040 if (!set
->ops
->queue_rq
)
3043 if (!set
->ops
->get_budget
^ !set
->ops
->put_budget
)
3046 if (set
->queue_depth
> BLK_MQ_MAX_DEPTH
) {
3047 pr_info("blk-mq: reduced tag depth to %u\n",
3049 set
->queue_depth
= BLK_MQ_MAX_DEPTH
;
3054 else if (set
->nr_maps
> HCTX_MAX_TYPES
)
3058 * If a crashdump is active, then we are potentially in a very
3059 * memory constrained environment. Limit us to 1 queue and
3060 * 64 tags to prevent using too much memory.
3062 if (is_kdump_kernel()) {
3063 set
->nr_hw_queues
= 1;
3065 set
->queue_depth
= min(64U, set
->queue_depth
);
3068 * There is no use for more h/w queues than cpus if we just have
3071 if (set
->nr_maps
== 1 && set
->nr_hw_queues
> nr_cpu_ids
)
3072 set
->nr_hw_queues
= nr_cpu_ids
;
3074 set
->tags
= kcalloc_node(nr_hw_queues(set
), sizeof(struct blk_mq_tags
*),
3075 GFP_KERNEL
, set
->numa_node
);
3080 for (i
= 0; i
< set
->nr_maps
; i
++) {
3081 set
->map
[i
].mq_map
= kcalloc_node(nr_cpu_ids
,
3082 sizeof(set
->map
[i
].mq_map
[0]),
3083 GFP_KERNEL
, set
->numa_node
);
3084 if (!set
->map
[i
].mq_map
)
3085 goto out_free_mq_map
;
3086 set
->map
[i
].nr_queues
= is_kdump_kernel() ? 1 : set
->nr_hw_queues
;
3089 ret
= blk_mq_update_queue_map(set
);
3091 goto out_free_mq_map
;
3093 ret
= blk_mq_alloc_rq_maps(set
);
3095 goto out_free_mq_map
;
3097 mutex_init(&set
->tag_list_lock
);
3098 INIT_LIST_HEAD(&set
->tag_list
);
3103 for (i
= 0; i
< set
->nr_maps
; i
++) {
3104 kfree(set
->map
[i
].mq_map
);
3105 set
->map
[i
].mq_map
= NULL
;
3111 EXPORT_SYMBOL(blk_mq_alloc_tag_set
);
3113 void blk_mq_free_tag_set(struct blk_mq_tag_set
*set
)
3117 for (i
= 0; i
< nr_hw_queues(set
); i
++)
3118 blk_mq_free_map_and_requests(set
, i
);
3120 for (j
= 0; j
< set
->nr_maps
; j
++) {
3121 kfree(set
->map
[j
].mq_map
);
3122 set
->map
[j
].mq_map
= NULL
;
3128 EXPORT_SYMBOL(blk_mq_free_tag_set
);
3130 int blk_mq_update_nr_requests(struct request_queue
*q
, unsigned int nr
)
3132 struct blk_mq_tag_set
*set
= q
->tag_set
;
3133 struct blk_mq_hw_ctx
*hctx
;
3139 if (q
->nr_requests
== nr
)
3142 blk_mq_freeze_queue(q
);
3143 blk_mq_quiesce_queue(q
);
3146 queue_for_each_hw_ctx(q
, hctx
, i
) {
3150 * If we're using an MQ scheduler, just update the scheduler
3151 * queue depth. This is similar to what the old code would do.
3153 if (!hctx
->sched_tags
) {
3154 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->tags
, nr
,
3157 ret
= blk_mq_tag_update_depth(hctx
, &hctx
->sched_tags
,
3162 if (q
->elevator
&& q
->elevator
->type
->ops
.depth_updated
)
3163 q
->elevator
->type
->ops
.depth_updated(hctx
);
3167 q
->nr_requests
= nr
;
3169 blk_mq_unquiesce_queue(q
);
3170 blk_mq_unfreeze_queue(q
);
3176 * request_queue and elevator_type pair.
3177 * It is just used by __blk_mq_update_nr_hw_queues to cache
3178 * the elevator_type associated with a request_queue.
3180 struct blk_mq_qe_pair
{
3181 struct list_head node
;
3182 struct request_queue
*q
;
3183 struct elevator_type
*type
;
3187 * Cache the elevator_type in qe pair list and switch the
3188 * io scheduler to 'none'
3190 static bool blk_mq_elv_switch_none(struct list_head
*head
,
3191 struct request_queue
*q
)
3193 struct blk_mq_qe_pair
*qe
;
3198 qe
= kmalloc(sizeof(*qe
), GFP_NOIO
| __GFP_NOWARN
| __GFP_NORETRY
);
3202 INIT_LIST_HEAD(&qe
->node
);
3204 qe
->type
= q
->elevator
->type
;
3205 list_add(&qe
->node
, head
);
3207 mutex_lock(&q
->sysfs_lock
);
3209 * After elevator_switch_mq, the previous elevator_queue will be
3210 * released by elevator_release. The reference of the io scheduler
3211 * module get by elevator_get will also be put. So we need to get
3212 * a reference of the io scheduler module here to prevent it to be
3215 __module_get(qe
->type
->elevator_owner
);
3216 elevator_switch_mq(q
, NULL
);
3217 mutex_unlock(&q
->sysfs_lock
);
3222 static void blk_mq_elv_switch_back(struct list_head
*head
,
3223 struct request_queue
*q
)
3225 struct blk_mq_qe_pair
*qe
;
3226 struct elevator_type
*t
= NULL
;
3228 list_for_each_entry(qe
, head
, node
)
3237 list_del(&qe
->node
);
3240 mutex_lock(&q
->sysfs_lock
);
3241 elevator_switch_mq(q
, t
);
3242 mutex_unlock(&q
->sysfs_lock
);
3245 static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
,
3248 struct request_queue
*q
;
3250 int prev_nr_hw_queues
;
3252 lockdep_assert_held(&set
->tag_list_lock
);
3254 if (set
->nr_maps
== 1 && nr_hw_queues
> nr_cpu_ids
)
3255 nr_hw_queues
= nr_cpu_ids
;
3256 if (nr_hw_queues
< 1 || nr_hw_queues
== set
->nr_hw_queues
)
3259 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3260 blk_mq_freeze_queue(q
);
3262 * Sync with blk_mq_queue_tag_busy_iter.
3266 * Switch IO scheduler to 'none', cleaning up the data associated
3267 * with the previous scheduler. We will switch back once we are done
3268 * updating the new sw to hw queue mappings.
3270 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3271 if (!blk_mq_elv_switch_none(&head
, q
))
3274 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3275 blk_mq_debugfs_unregister_hctxs(q
);
3276 blk_mq_sysfs_unregister(q
);
3279 prev_nr_hw_queues
= set
->nr_hw_queues
;
3280 set
->nr_hw_queues
= nr_hw_queues
;
3281 blk_mq_update_queue_map(set
);
3283 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3284 blk_mq_realloc_hw_ctxs(set
, q
);
3285 if (q
->nr_hw_queues
!= set
->nr_hw_queues
) {
3286 pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
3287 nr_hw_queues
, prev_nr_hw_queues
);
3288 set
->nr_hw_queues
= prev_nr_hw_queues
;
3289 blk_mq_map_queues(&set
->map
[HCTX_TYPE_DEFAULT
]);
3292 blk_mq_map_swqueue(q
);
3295 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
) {
3296 blk_mq_sysfs_register(q
);
3297 blk_mq_debugfs_register_hctxs(q
);
3301 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3302 blk_mq_elv_switch_back(&head
, q
);
3304 list_for_each_entry(q
, &set
->tag_list
, tag_set_list
)
3305 blk_mq_unfreeze_queue(q
);
3308 void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set
*set
, int nr_hw_queues
)
3310 mutex_lock(&set
->tag_list_lock
);
3311 __blk_mq_update_nr_hw_queues(set
, nr_hw_queues
);
3312 mutex_unlock(&set
->tag_list_lock
);
3314 EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues
);
3316 /* Enable polling stats and return whether they were already enabled. */
3317 static bool blk_poll_stats_enable(struct request_queue
*q
)
3319 if (test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3320 blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS
, q
))
3322 blk_stat_add_callback(q
, q
->poll_cb
);
3326 static void blk_mq_poll_stats_start(struct request_queue
*q
)
3329 * We don't arm the callback if polling stats are not enabled or the
3330 * callback is already active.
3332 if (!test_bit(QUEUE_FLAG_POLL_STATS
, &q
->queue_flags
) ||
3333 blk_stat_is_active(q
->poll_cb
))
3336 blk_stat_activate_msecs(q
->poll_cb
, 100);
3339 static void blk_mq_poll_stats_fn(struct blk_stat_callback
*cb
)
3341 struct request_queue
*q
= cb
->data
;
3344 for (bucket
= 0; bucket
< BLK_MQ_POLL_STATS_BKTS
; bucket
++) {
3345 if (cb
->stat
[bucket
].nr_samples
)
3346 q
->poll_stat
[bucket
] = cb
->stat
[bucket
];
3350 static unsigned long blk_mq_poll_nsecs(struct request_queue
*q
,
3351 struct blk_mq_hw_ctx
*hctx
,
3354 unsigned long ret
= 0;
3358 * If stats collection isn't on, don't sleep but turn it on for
3361 if (!blk_poll_stats_enable(q
))
3365 * As an optimistic guess, use half of the mean service time
3366 * for this type of request. We can (and should) make this smarter.
3367 * For instance, if the completion latencies are tight, we can
3368 * get closer than just half the mean. This is especially
3369 * important on devices where the completion latencies are longer
3370 * than ~10 usec. We do use the stats for the relevant IO size
3371 * if available which does lead to better estimates.
3373 bucket
= blk_mq_poll_stats_bkt(rq
);
3377 if (q
->poll_stat
[bucket
].nr_samples
)
3378 ret
= (q
->poll_stat
[bucket
].mean
+ 1) / 2;
3383 static bool blk_mq_poll_hybrid_sleep(struct request_queue
*q
,
3384 struct blk_mq_hw_ctx
*hctx
,
3387 struct hrtimer_sleeper hs
;
3388 enum hrtimer_mode mode
;
3392 if (rq
->rq_flags
& RQF_MQ_POLL_SLEPT
)
3396 * If we get here, hybrid polling is enabled. Hence poll_nsec can be:
3398 * 0: use half of prev avg
3399 * >0: use this specific value
3401 if (q
->poll_nsec
> 0)
3402 nsecs
= q
->poll_nsec
;
3404 nsecs
= blk_mq_poll_nsecs(q
, hctx
, rq
);
3409 rq
->rq_flags
|= RQF_MQ_POLL_SLEPT
;
3412 * This will be replaced with the stats tracking code, using
3413 * 'avg_completion_time / 2' as the pre-sleep target.
3417 mode
= HRTIMER_MODE_REL
;
3418 hrtimer_init_on_stack(&hs
.timer
, CLOCK_MONOTONIC
, mode
);
3419 hrtimer_set_expires(&hs
.timer
, kt
);
3421 hrtimer_init_sleeper(&hs
, current
);
3423 if (blk_mq_rq_state(rq
) == MQ_RQ_COMPLETE
)
3425 set_current_state(TASK_UNINTERRUPTIBLE
);
3426 hrtimer_start_expires(&hs
.timer
, mode
);
3429 hrtimer_cancel(&hs
.timer
);
3430 mode
= HRTIMER_MODE_ABS
;
3431 } while (hs
.task
&& !signal_pending(current
));
3433 __set_current_state(TASK_RUNNING
);
3434 destroy_hrtimer_on_stack(&hs
.timer
);
3438 static bool blk_mq_poll_hybrid(struct request_queue
*q
,
3439 struct blk_mq_hw_ctx
*hctx
, blk_qc_t cookie
)
3443 if (q
->poll_nsec
== BLK_MQ_POLL_CLASSIC
)
3446 if (!blk_qc_t_is_internal(cookie
))
3447 rq
= blk_mq_tag_to_rq(hctx
->tags
, blk_qc_t_to_tag(cookie
));
3449 rq
= blk_mq_tag_to_rq(hctx
->sched_tags
, blk_qc_t_to_tag(cookie
));
3451 * With scheduling, if the request has completed, we'll
3452 * get a NULL return here, as we clear the sched tag when
3453 * that happens. The request still remains valid, like always,
3454 * so we should be safe with just the NULL check.
3460 return blk_mq_poll_hybrid_sleep(q
, hctx
, rq
);
3464 * blk_poll - poll for IO completions
3466 * @cookie: cookie passed back at IO submission time
3467 * @spin: whether to spin for completions
3470 * Poll for completions on the passed in queue. Returns number of
3471 * completed entries found. If @spin is true, then blk_poll will continue
3472 * looping until at least one completion is found, unless the task is
3473 * otherwise marked running (or we need to reschedule).
3475 int blk_poll(struct request_queue
*q
, blk_qc_t cookie
, bool spin
)
3477 struct blk_mq_hw_ctx
*hctx
;
3480 if (!blk_qc_t_valid(cookie
) ||
3481 !test_bit(QUEUE_FLAG_POLL
, &q
->queue_flags
))
3485 blk_flush_plug_list(current
->plug
, false);
3487 hctx
= q
->queue_hw_ctx
[blk_qc_t_to_queue_num(cookie
)];
3490 * If we sleep, have the caller restart the poll loop to reset
3491 * the state. Like for the other success return cases, the
3492 * caller is responsible for checking if the IO completed. If
3493 * the IO isn't complete, we'll get called again and will go
3494 * straight to the busy poll loop.
3496 if (blk_mq_poll_hybrid(q
, hctx
, cookie
))
3499 hctx
->poll_considered
++;
3501 state
= current
->state
;
3505 hctx
->poll_invoked
++;
3507 ret
= q
->mq_ops
->poll(hctx
);
3509 hctx
->poll_success
++;
3510 __set_current_state(TASK_RUNNING
);
3514 if (signal_pending_state(state
, current
))
3515 __set_current_state(TASK_RUNNING
);
3517 if (current
->state
== TASK_RUNNING
)
3519 if (ret
< 0 || !spin
)
3522 } while (!need_resched());
3524 __set_current_state(TASK_RUNNING
);
3527 EXPORT_SYMBOL_GPL(blk_poll
);
3529 unsigned int blk_mq_rq_cpu(struct request
*rq
)
3531 return rq
->mq_ctx
->cpu
;
3533 EXPORT_SYMBOL(blk_mq_rq_cpu
);
3535 static int __init
blk_mq_init(void)
3537 cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD
, "block/mq:dead", NULL
,
3538 blk_mq_hctx_notify_dead
);
3541 subsys_initcall(blk_mq_init
);