1 #include <linux/kernel.h>
2 #include <linux/module.h>
3 #include <linux/backing-dev.h>
5 #include <linux/blkdev.h>
7 #include <linux/init.h>
8 #include <linux/slab.h>
9 #include <linux/workqueue.h>
10 #include <linux/smp.h>
11 #include <linux/llist.h>
12 #include <linux/list_sort.h>
13 #include <linux/cpu.h>
14 #include <linux/cache.h>
15 #include <linux/sched/sysctl.h>
16 #include <linux/delay.h>
18 #include <trace/events/block.h>
20 #include <linux/blk-mq.h>
23 #include "blk-mq-tag.h"
25 static DEFINE_MUTEX(all_q_mutex);
26 static LIST_HEAD(all_q_list);
28 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx);
30 static struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
33 return per_cpu_ptr(q->queue_ctx, cpu);
37 * This assumes per-cpu software queueing queues. They could be per-node
38 * as well, for instance. For now this is hardcoded as-is. Note that we don't
39 * care about preemption, since we know the ctx's are persistent. This does
40 * mean that we can't rely on ctx always matching the currently running CPU.
42 static struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q)
44 return __blk_mq_get_ctx(q, get_cpu());
47 static void blk_mq_put_ctx(struct blk_mq_ctx *ctx)
53 * Check if any of the ctx's have pending work in this hardware queue
55 static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
59 for (i = 0; i < hctx->nr_ctx_map; i++)
67 * Mark this ctx as having pending work in this hardware queue
69 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
70 struct blk_mq_ctx *ctx)
72 if (!test_bit(ctx->index_hw, hctx->ctx_map))
73 set_bit(ctx->index_hw, hctx->ctx_map);
76 static struct request *blk_mq_alloc_rq(struct blk_mq_hw_ctx *hctx, gfp_t gfp,
82 tag = blk_mq_get_tag(hctx->tags, gfp, reserved);
83 if (tag != BLK_MQ_TAG_FAIL) {
93 static int blk_mq_queue_enter(struct request_queue *q)
97 __percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
99 /* we have problems to freeze the queue if it's initializing */
100 if (!blk_queue_bypass(q) || !blk_queue_init_done(q))
103 __percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
105 spin_lock_irq(q->queue_lock);
106 ret = wait_event_interruptible_lock_irq(q->mq_freeze_wq,
107 !blk_queue_bypass(q) || blk_queue_dying(q),
109 /* inc usage with lock hold to avoid freeze_queue runs here */
110 if (!ret && !blk_queue_dying(q))
111 __percpu_counter_add(&q->mq_usage_counter, 1, 1000000);
112 else if (blk_queue_dying(q))
114 spin_unlock_irq(q->queue_lock);
119 static void blk_mq_queue_exit(struct request_queue *q)
121 __percpu_counter_add(&q->mq_usage_counter, -1, 1000000);
124 static void __blk_mq_drain_queue(struct request_queue *q)
129 spin_lock_irq(q->queue_lock);
130 count = percpu_counter_sum(&q->mq_usage_counter);
131 spin_unlock_irq(q->queue_lock);
135 blk_mq_run_queues(q, false);
141 * Guarantee no request is in use, so we can change any data structure of
142 * the queue afterward.
144 static void blk_mq_freeze_queue(struct request_queue *q)
148 spin_lock_irq(q->queue_lock);
149 drain = !q->bypass_depth++;
150 queue_flag_set(QUEUE_FLAG_BYPASS, q);
151 spin_unlock_irq(q->queue_lock);
154 __blk_mq_drain_queue(q);
157 void blk_mq_drain_queue(struct request_queue *q)
159 __blk_mq_drain_queue(q);
162 static void blk_mq_unfreeze_queue(struct request_queue *q)
166 spin_lock_irq(q->queue_lock);
167 if (!--q->bypass_depth) {
168 queue_flag_clear(QUEUE_FLAG_BYPASS, q);
171 WARN_ON_ONCE(q->bypass_depth < 0);
172 spin_unlock_irq(q->queue_lock);
174 wake_up_all(&q->mq_freeze_wq);
177 bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
179 return blk_mq_has_free_tags(hctx->tags);
181 EXPORT_SYMBOL(blk_mq_can_queue);
183 static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
184 struct request *rq, unsigned int rw_flags)
186 if (blk_queue_io_stat(q))
187 rw_flags |= REQ_IO_STAT;
190 rq->cmd_flags = rw_flags;
191 rq->start_time = jiffies;
192 set_start_time_ns(rq);
193 ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
196 static struct request *__blk_mq_alloc_request(struct blk_mq_hw_ctx *hctx,
197 gfp_t gfp, bool reserved)
199 return blk_mq_alloc_rq(hctx, gfp, reserved);
202 static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
209 struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
210 struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);
212 rq = __blk_mq_alloc_request(hctx, gfp & ~__GFP_WAIT, reserved);
214 blk_mq_rq_ctx_init(q, ctx, rq, rw);
219 if (!(gfp & __GFP_WAIT))
222 __blk_mq_run_hw_queue(hctx);
223 blk_mq_wait_for_tags(hctx->tags);
229 struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
230 gfp_t gfp, bool reserved)
234 if (blk_mq_queue_enter(q))
237 rq = blk_mq_alloc_request_pinned(q, rw, gfp, reserved);
239 blk_mq_put_ctx(rq->mq_ctx);
243 struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
248 if (blk_mq_queue_enter(q))
251 rq = blk_mq_alloc_request_pinned(q, rw, gfp, true);
253 blk_mq_put_ctx(rq->mq_ctx);
256 EXPORT_SYMBOL(blk_mq_alloc_reserved_request);
259 * Re-init and set pdu, if we have it
261 static void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq)
263 blk_rq_init(hctx->queue, rq);
266 rq->special = blk_mq_rq_to_pdu(rq);
269 static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
270 struct blk_mq_ctx *ctx, struct request *rq)
272 const int tag = rq->tag;
273 struct request_queue *q = rq->q;
275 blk_mq_rq_init(hctx, rq);
276 blk_mq_put_tag(hctx->tags, tag);
278 blk_mq_queue_exit(q);
281 void blk_mq_free_request(struct request *rq)
283 struct blk_mq_ctx *ctx = rq->mq_ctx;
284 struct blk_mq_hw_ctx *hctx;
285 struct request_queue *q = rq->q;
287 ctx->rq_completed[rq_is_sync(rq)]++;
289 hctx = q->mq_ops->map_queue(q, ctx->cpu);
290 __blk_mq_free_request(hctx, ctx, rq);
293 static void blk_mq_bio_endio(struct request *rq, struct bio *bio, int error)
296 clear_bit(BIO_UPTODATE, &bio->bi_flags);
297 else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
300 if (unlikely(rq->cmd_flags & REQ_QUIET))
301 set_bit(BIO_QUIET, &bio->bi_flags);
303 /* don't actually finish bio if it's part of flush sequence */
304 if (!(rq->cmd_flags & REQ_FLUSH_SEQ))
305 bio_endio(bio, error);
308 void blk_mq_complete_request(struct request *rq, int error)
310 struct bio *bio = rq->bio;
311 unsigned int bytes = 0;
313 trace_block_rq_complete(rq->q, rq);
316 struct bio *next = bio->bi_next;
319 bytes += bio->bi_iter.bi_size;
320 blk_mq_bio_endio(rq, bio, error);
324 blk_account_io_completion(rq, bytes);
326 blk_account_io_done(rq);
329 rq->end_io(rq, error);
331 blk_mq_free_request(rq);
334 void __blk_mq_end_io(struct request *rq, int error)
336 if (!blk_mark_rq_complete(rq))
337 blk_mq_complete_request(rq, error);
340 static void blk_mq_end_io_remote(void *data)
342 struct request *rq = data;
344 __blk_mq_end_io(rq, rq->errors);
348 * End IO on this request on a multiqueue enabled driver. We'll either do
349 * it directly inline, or punt to a local IPI handler on the matching
352 void blk_mq_end_io(struct request *rq, int error)
354 struct blk_mq_ctx *ctx = rq->mq_ctx;
357 if (!ctx->ipi_redirect)
358 return __blk_mq_end_io(rq, error);
361 if (cpu != ctx->cpu && cpu_online(ctx->cpu)) {
363 rq->csd.func = blk_mq_end_io_remote;
366 __smp_call_function_single(ctx->cpu, &rq->csd, 0);
368 __blk_mq_end_io(rq, error);
372 EXPORT_SYMBOL(blk_mq_end_io);
374 static void blk_mq_start_request(struct request *rq)
376 struct request_queue *q = rq->q;
378 trace_block_rq_issue(q, rq);
381 * Just mark start time and set the started bit. Due to memory
382 * ordering, we know we'll see the correct deadline as long as
383 * REQ_ATOMIC_STARTED is seen.
385 rq->deadline = jiffies + q->rq_timeout;
386 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
389 static void blk_mq_requeue_request(struct request *rq)
391 struct request_queue *q = rq->q;
393 trace_block_rq_requeue(q, rq);
394 clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
397 struct blk_mq_timeout_data {
398 struct blk_mq_hw_ctx *hctx;
400 unsigned int *next_set;
403 static void blk_mq_timeout_check(void *__data, unsigned long *free_tags)
405 struct blk_mq_timeout_data *data = __data;
406 struct blk_mq_hw_ctx *hctx = data->hctx;
409 /* It may not be in flight yet (this is where
410 * the REQ_ATOMIC_STARTED flag comes in). The requests are
411 * statically allocated, so we know it's always safe to access the
412 * memory associated with a bit offset into ->rqs[].
418 tag = find_next_zero_bit(free_tags, hctx->queue_depth, tag);
419 if (tag >= hctx->queue_depth)
422 rq = hctx->rqs[tag++];
424 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
427 blk_rq_check_expired(rq, data->next, data->next_set);
431 static void blk_mq_hw_ctx_check_timeout(struct blk_mq_hw_ctx *hctx,
433 unsigned int *next_set)
435 struct blk_mq_timeout_data data = {
438 .next_set = next_set,
442 * Ask the tagging code to iterate busy requests, so we can
443 * check them for timeout.
445 blk_mq_tag_busy_iter(hctx->tags, blk_mq_timeout_check, &data);
448 static void blk_mq_rq_timer(unsigned long data)
450 struct request_queue *q = (struct request_queue *) data;
451 struct blk_mq_hw_ctx *hctx;
452 unsigned long next = 0;
455 queue_for_each_hw_ctx(q, hctx, i)
456 blk_mq_hw_ctx_check_timeout(hctx, &next, &next_set);
459 mod_timer(&q->timeout, round_jiffies_up(next));
463 * Reverse check our software queue for entries that we could potentially
464 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
465 * too much time checking for merges.
467 static bool blk_mq_attempt_merge(struct request_queue *q,
468 struct blk_mq_ctx *ctx, struct bio *bio)
473 list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
479 if (!blk_rq_merge_ok(rq, bio))
482 el_ret = blk_try_merge(rq, bio);
483 if (el_ret == ELEVATOR_BACK_MERGE) {
484 if (bio_attempt_back_merge(q, rq, bio)) {
489 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
490 if (bio_attempt_front_merge(q, rq, bio)) {
501 void blk_mq_add_timer(struct request *rq)
503 __blk_add_timer(rq, NULL);
507 * Run this hardware queue, pulling any software queues mapped to it in.
508 * Note that this function currently has various problems around ordering
509 * of IO. In particular, we'd like FIFO behaviour on handling existing
510 * items on the hctx->dispatch list. Ignore that for now.
512 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
514 struct request_queue *q = hctx->queue;
515 struct blk_mq_ctx *ctx;
520 if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->flags)))
526 * Touch any software queue that has pending entries.
528 for_each_set_bit(bit, hctx->ctx_map, hctx->nr_ctx) {
529 clear_bit(bit, hctx->ctx_map);
530 ctx = hctx->ctxs[bit];
531 BUG_ON(bit != ctx->index_hw);
533 spin_lock(&ctx->lock);
534 list_splice_tail_init(&ctx->rq_list, &rq_list);
535 spin_unlock(&ctx->lock);
539 * If we have previous entries on our dispatch list, grab them
540 * and stuff them at the front for more fair dispatch.
542 if (!list_empty_careful(&hctx->dispatch)) {
543 spin_lock(&hctx->lock);
544 if (!list_empty(&hctx->dispatch))
545 list_splice_init(&hctx->dispatch, &rq_list);
546 spin_unlock(&hctx->lock);
550 * Delete and return all entries from our dispatch list
555 * Now process all the entries, sending them to the driver.
557 while (!list_empty(&rq_list)) {
560 rq = list_first_entry(&rq_list, struct request, queuelist);
561 list_del_init(&rq->queuelist);
562 blk_mq_start_request(rq);
565 * Last request in the series. Flag it as such, this
566 * enables drivers to know when IO should be kicked off,
567 * if they don't do it on a per-request basis.
569 * Note: the flag isn't the only condition drivers
570 * should do kick off. If drive is busy, the last
571 * request might not have the bit set.
573 if (list_empty(&rq_list))
574 rq->cmd_flags |= REQ_END;
576 ret = q->mq_ops->queue_rq(hctx, rq);
578 case BLK_MQ_RQ_QUEUE_OK:
581 case BLK_MQ_RQ_QUEUE_BUSY:
583 * FIXME: we should have a mechanism to stop the queue
584 * like blk_stop_queue, otherwise we will waste cpu
587 list_add(&rq->queuelist, &rq_list);
588 blk_mq_requeue_request(rq);
591 pr_err("blk-mq: bad return on queue: %d\n", ret);
593 case BLK_MQ_RQ_QUEUE_ERROR:
594 blk_mq_end_io(rq, rq->errors);
598 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
603 hctx->dispatched[0]++;
604 else if (queued < (1 << (BLK_MQ_MAX_DISPATCH_ORDER - 1)))
605 hctx->dispatched[ilog2(queued) + 1]++;
608 * Any items that need requeuing? Stuff them into hctx->dispatch,
609 * that is where we will continue on next queue run.
611 if (!list_empty(&rq_list)) {
612 spin_lock(&hctx->lock);
613 list_splice(&rq_list, &hctx->dispatch);
614 spin_unlock(&hctx->lock);
618 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
620 if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->flags)))
624 __blk_mq_run_hw_queue(hctx);
626 struct request_queue *q = hctx->queue;
628 kblockd_schedule_delayed_work(q, &hctx->delayed_work, 0);
632 void blk_mq_run_queues(struct request_queue *q, bool async)
634 struct blk_mq_hw_ctx *hctx;
637 queue_for_each_hw_ctx(q, hctx, i) {
638 if ((!blk_mq_hctx_has_pending(hctx) &&
639 list_empty_careful(&hctx->dispatch)) ||
640 test_bit(BLK_MQ_S_STOPPED, &hctx->flags))
643 blk_mq_run_hw_queue(hctx, async);
646 EXPORT_SYMBOL(blk_mq_run_queues);
648 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
650 cancel_delayed_work(&hctx->delayed_work);
651 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
653 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
655 void blk_mq_stop_hw_queues(struct request_queue *q)
657 struct blk_mq_hw_ctx *hctx;
660 queue_for_each_hw_ctx(q, hctx, i)
661 blk_mq_stop_hw_queue(hctx);
663 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
665 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
667 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
668 __blk_mq_run_hw_queue(hctx);
670 EXPORT_SYMBOL(blk_mq_start_hw_queue);
672 void blk_mq_start_stopped_hw_queues(struct request_queue *q)
674 struct blk_mq_hw_ctx *hctx;
677 queue_for_each_hw_ctx(q, hctx, i) {
678 if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
681 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
682 blk_mq_run_hw_queue(hctx, true);
685 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
687 static void blk_mq_work_fn(struct work_struct *work)
689 struct blk_mq_hw_ctx *hctx;
691 hctx = container_of(work, struct blk_mq_hw_ctx, delayed_work.work);
692 __blk_mq_run_hw_queue(hctx);
695 static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
698 struct blk_mq_ctx *ctx = rq->mq_ctx;
700 trace_block_rq_insert(hctx->queue, rq);
702 list_add_tail(&rq->queuelist, &ctx->rq_list);
703 blk_mq_hctx_mark_pending(hctx, ctx);
706 * We do this early, to ensure we are on the right CPU.
708 blk_mq_add_timer(rq);
711 void blk_mq_insert_request(struct request_queue *q, struct request *rq,
714 struct blk_mq_hw_ctx *hctx;
715 struct blk_mq_ctx *ctx, *current_ctx;
718 hctx = q->mq_ops->map_queue(q, ctx->cpu);
720 if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
721 blk_insert_flush(rq);
723 current_ctx = blk_mq_get_ctx(q);
725 if (!cpu_online(ctx->cpu)) {
727 hctx = q->mq_ops->map_queue(q, ctx->cpu);
730 spin_lock(&ctx->lock);
731 __blk_mq_insert_request(hctx, rq);
732 spin_unlock(&ctx->lock);
734 blk_mq_put_ctx(current_ctx);
738 __blk_mq_run_hw_queue(hctx);
740 EXPORT_SYMBOL(blk_mq_insert_request);
743 * This is a special version of blk_mq_insert_request to bypass FLUSH request
744 * check. Should only be used internally.
746 void blk_mq_run_request(struct request *rq, bool run_queue, bool async)
748 struct request_queue *q = rq->q;
749 struct blk_mq_hw_ctx *hctx;
750 struct blk_mq_ctx *ctx, *current_ctx;
752 current_ctx = blk_mq_get_ctx(q);
755 if (!cpu_online(ctx->cpu)) {
759 hctx = q->mq_ops->map_queue(q, ctx->cpu);
761 /* ctx->cpu might be offline */
762 spin_lock(&ctx->lock);
763 __blk_mq_insert_request(hctx, rq);
764 spin_unlock(&ctx->lock);
766 blk_mq_put_ctx(current_ctx);
769 blk_mq_run_hw_queue(hctx, async);
772 static void blk_mq_insert_requests(struct request_queue *q,
773 struct blk_mq_ctx *ctx,
774 struct list_head *list,
779 struct blk_mq_hw_ctx *hctx;
780 struct blk_mq_ctx *current_ctx;
782 trace_block_unplug(q, depth, !from_schedule);
784 current_ctx = blk_mq_get_ctx(q);
786 if (!cpu_online(ctx->cpu))
788 hctx = q->mq_ops->map_queue(q, ctx->cpu);
791 * preemption doesn't flush plug list, so it's possible ctx->cpu is
794 spin_lock(&ctx->lock);
795 while (!list_empty(list)) {
798 rq = list_first_entry(list, struct request, queuelist);
799 list_del_init(&rq->queuelist);
801 __blk_mq_insert_request(hctx, rq);
803 spin_unlock(&ctx->lock);
805 blk_mq_put_ctx(current_ctx);
807 blk_mq_run_hw_queue(hctx, from_schedule);
810 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
812 struct request *rqa = container_of(a, struct request, queuelist);
813 struct request *rqb = container_of(b, struct request, queuelist);
815 return !(rqa->mq_ctx < rqb->mq_ctx ||
816 (rqa->mq_ctx == rqb->mq_ctx &&
817 blk_rq_pos(rqa) < blk_rq_pos(rqb)));
820 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
822 struct blk_mq_ctx *this_ctx;
823 struct request_queue *this_q;
829 list_splice_init(&plug->mq_list, &list);
831 list_sort(NULL, &list, plug_ctx_cmp);
837 while (!list_empty(&list)) {
838 rq = list_entry_rq(list.next);
839 list_del_init(&rq->queuelist);
841 if (rq->mq_ctx != this_ctx) {
843 blk_mq_insert_requests(this_q, this_ctx,
848 this_ctx = rq->mq_ctx;
854 list_add_tail(&rq->queuelist, &ctx_list);
858 * If 'this_ctx' is set, we know we have entries to complete
859 * on 'ctx_list'. Do those.
862 blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
867 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
869 init_request_from_bio(rq, bio);
870 blk_account_io_start(rq, 1);
873 static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
875 struct blk_mq_hw_ctx *hctx;
876 struct blk_mq_ctx *ctx;
877 const int is_sync = rw_is_sync(bio->bi_rw);
878 const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
879 int rw = bio_data_dir(bio);
881 unsigned int use_plug, request_count = 0;
884 * If we have multiple hardware queues, just go directly to
885 * one of those for sync IO.
887 use_plug = !is_flush_fua && ((q->nr_hw_queues == 1) || !is_sync);
889 blk_queue_bounce(q, &bio);
891 if (use_plug && blk_attempt_plug_merge(q, bio, &request_count))
894 if (blk_mq_queue_enter(q)) {
895 bio_endio(bio, -EIO);
899 ctx = blk_mq_get_ctx(q);
900 hctx = q->mq_ops->map_queue(q, ctx->cpu);
902 trace_block_getrq(q, bio, rw);
903 rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, false);
905 blk_mq_rq_ctx_init(q, ctx, rq, rw);
908 trace_block_sleeprq(q, bio, rw);
909 rq = blk_mq_alloc_request_pinned(q, rw, __GFP_WAIT|GFP_ATOMIC,
912 hctx = q->mq_ops->map_queue(q, ctx->cpu);
917 if (unlikely(is_flush_fua)) {
918 blk_mq_bio_to_request(rq, bio);
920 blk_insert_flush(rq);
925 * A task plug currently exists. Since this is completely lockless,
926 * utilize that to temporarily store requests until the task is
927 * either done or scheduled away.
930 struct blk_plug *plug = current->plug;
933 blk_mq_bio_to_request(rq, bio);
934 if (list_empty(&plug->mq_list))
936 else if (request_count >= BLK_MAX_REQUEST_COUNT) {
937 blk_flush_plug_list(plug, false);
940 list_add_tail(&rq->queuelist, &plug->mq_list);
946 spin_lock(&ctx->lock);
948 if ((hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
949 blk_mq_attempt_merge(q, ctx, bio))
950 __blk_mq_free_request(hctx, ctx, rq);
952 blk_mq_bio_to_request(rq, bio);
953 __blk_mq_insert_request(hctx, rq);
956 spin_unlock(&ctx->lock);
960 * For a SYNC request, send it to the hardware immediately. For an
961 * ASYNC request, just ensure that we run it later on. The latter
962 * allows for merging opportunities and more efficient dispatching.
965 blk_mq_run_hw_queue(hctx, !is_sync || is_flush_fua);
969 * Default mapping to a software queue, since we use one per CPU.
971 struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q, const int cpu)
973 return q->queue_hw_ctx[q->mq_map[cpu]];
975 EXPORT_SYMBOL(blk_mq_map_queue);
977 struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_reg *reg,
978 unsigned int hctx_index)
980 return kmalloc_node(sizeof(struct blk_mq_hw_ctx),
981 GFP_KERNEL | __GFP_ZERO, reg->numa_node);
983 EXPORT_SYMBOL(blk_mq_alloc_single_hw_queue);
985 void blk_mq_free_single_hw_queue(struct blk_mq_hw_ctx *hctx,
986 unsigned int hctx_index)
990 EXPORT_SYMBOL(blk_mq_free_single_hw_queue);
992 static void blk_mq_hctx_notify(void *data, unsigned long action,
995 struct blk_mq_hw_ctx *hctx = data;
996 struct blk_mq_ctx *ctx;
999 if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
1003 * Move ctx entries to new CPU, if this one is going away.
1005 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
1007 spin_lock(&ctx->lock);
1008 if (!list_empty(&ctx->rq_list)) {
1009 list_splice_init(&ctx->rq_list, &tmp);
1010 clear_bit(ctx->index_hw, hctx->ctx_map);
1012 spin_unlock(&ctx->lock);
1014 if (list_empty(&tmp))
1017 ctx = blk_mq_get_ctx(hctx->queue);
1018 spin_lock(&ctx->lock);
1020 while (!list_empty(&tmp)) {
1023 rq = list_first_entry(&tmp, struct request, queuelist);
1025 list_move_tail(&rq->queuelist, &ctx->rq_list);
1028 blk_mq_hctx_mark_pending(hctx, ctx);
1030 spin_unlock(&ctx->lock);
1031 blk_mq_put_ctx(ctx);
1034 static void blk_mq_init_hw_commands(struct blk_mq_hw_ctx *hctx,
1035 void (*init)(void *, struct blk_mq_hw_ctx *,
1036 struct request *, unsigned int),
1041 for (i = 0; i < hctx->queue_depth; i++) {
1042 struct request *rq = hctx->rqs[i];
1044 init(data, hctx, rq, i);
1048 void blk_mq_init_commands(struct request_queue *q,
1049 void (*init)(void *, struct blk_mq_hw_ctx *,
1050 struct request *, unsigned int),
1053 struct blk_mq_hw_ctx *hctx;
1056 queue_for_each_hw_ctx(q, hctx, i)
1057 blk_mq_init_hw_commands(hctx, init, data);
1059 EXPORT_SYMBOL(blk_mq_init_commands);
1061 static void blk_mq_free_rq_map(struct blk_mq_hw_ctx *hctx)
1065 while (!list_empty(&hctx->page_list)) {
1066 page = list_first_entry(&hctx->page_list, struct page, lru);
1067 list_del_init(&page->lru);
1068 __free_pages(page, page->private);
1074 blk_mq_free_tags(hctx->tags);
1077 static size_t order_to_size(unsigned int order)
1079 size_t ret = PAGE_SIZE;
1087 static int blk_mq_init_rq_map(struct blk_mq_hw_ctx *hctx,
1088 unsigned int reserved_tags, int node)
1090 unsigned int i, j, entries_per_page, max_order = 4;
1091 size_t rq_size, left;
1093 INIT_LIST_HEAD(&hctx->page_list);
1095 hctx->rqs = kmalloc_node(hctx->queue_depth * sizeof(struct request *),
1101 * rq_size is the size of the request plus driver payload, rounded
1102 * to the cacheline size
1104 rq_size = round_up(sizeof(struct request) + hctx->cmd_size,
1106 left = rq_size * hctx->queue_depth;
1108 for (i = 0; i < hctx->queue_depth;) {
1109 int this_order = max_order;
1114 while (left < order_to_size(this_order - 1) && this_order)
1118 page = alloc_pages_node(node, GFP_KERNEL, this_order);
1123 if (order_to_size(this_order) < rq_size)
1130 page->private = this_order;
1131 list_add_tail(&page->lru, &hctx->page_list);
1133 p = page_address(page);
1134 entries_per_page = order_to_size(this_order) / rq_size;
1135 to_do = min(entries_per_page, hctx->queue_depth - i);
1136 left -= to_do * rq_size;
1137 for (j = 0; j < to_do; j++) {
1139 blk_mq_rq_init(hctx, hctx->rqs[i]);
1145 if (i < (reserved_tags + BLK_MQ_TAG_MIN))
1147 else if (i != hctx->queue_depth) {
1148 hctx->queue_depth = i;
1149 pr_warn("%s: queue depth set to %u because of low memory\n",
1153 hctx->tags = blk_mq_init_tags(hctx->queue_depth, reserved_tags, node);
1156 blk_mq_free_rq_map(hctx);
1163 static int blk_mq_init_hw_queues(struct request_queue *q,
1164 struct blk_mq_reg *reg, void *driver_data)
1166 struct blk_mq_hw_ctx *hctx;
1170 * Initialize hardware queues
1172 queue_for_each_hw_ctx(q, hctx, i) {
1173 unsigned int num_maps;
1176 node = hctx->numa_node;
1177 if (node == NUMA_NO_NODE)
1178 node = hctx->numa_node = reg->numa_node;
1180 INIT_DELAYED_WORK(&hctx->delayed_work, blk_mq_work_fn);
1181 spin_lock_init(&hctx->lock);
1182 INIT_LIST_HEAD(&hctx->dispatch);
1184 hctx->queue_num = i;
1185 hctx->flags = reg->flags;
1186 hctx->queue_depth = reg->queue_depth;
1187 hctx->cmd_size = reg->cmd_size;
1189 blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
1190 blk_mq_hctx_notify, hctx);
1191 blk_mq_register_cpu_notifier(&hctx->cpu_notifier);
1193 if (blk_mq_init_rq_map(hctx, reg->reserved_tags, node))
1197 * Allocate space for all possible cpus to avoid allocation in
1200 hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1205 num_maps = ALIGN(nr_cpu_ids, BITS_PER_LONG) / BITS_PER_LONG;
1206 hctx->ctx_map = kzalloc_node(num_maps * sizeof(unsigned long),
1211 hctx->nr_ctx_map = num_maps;
1214 if (reg->ops->init_hctx &&
1215 reg->ops->init_hctx(hctx, driver_data, i))
1219 if (i == q->nr_hw_queues)
1225 queue_for_each_hw_ctx(q, hctx, j) {
1229 if (reg->ops->exit_hctx)
1230 reg->ops->exit_hctx(hctx, j);
1232 blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1233 blk_mq_free_rq_map(hctx);
1240 static void blk_mq_init_cpu_queues(struct request_queue *q,
1241 unsigned int nr_hw_queues)
1245 for_each_possible_cpu(i) {
1246 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1247 struct blk_mq_hw_ctx *hctx;
1249 memset(__ctx, 0, sizeof(*__ctx));
1251 spin_lock_init(&__ctx->lock);
1252 INIT_LIST_HEAD(&__ctx->rq_list);
1255 /* If the cpu isn't online, the cpu is mapped to first hctx */
1256 hctx = q->mq_ops->map_queue(q, i);
1263 * Set local node, IFF we have more than one hw queue. If
1264 * not, we remain on the home node of the device
1266 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
1267 hctx->numa_node = cpu_to_node(i);
1271 static void blk_mq_map_swqueue(struct request_queue *q)
1274 struct blk_mq_hw_ctx *hctx;
1275 struct blk_mq_ctx *ctx;
1277 queue_for_each_hw_ctx(q, hctx, i) {
1282 * Map software to hardware queues
1284 queue_for_each_ctx(q, ctx, i) {
1285 /* If the cpu isn't online, the cpu is mapped to first hctx */
1286 hctx = q->mq_ops->map_queue(q, i);
1287 ctx->index_hw = hctx->nr_ctx;
1288 hctx->ctxs[hctx->nr_ctx++] = ctx;
1292 struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
1295 struct blk_mq_hw_ctx **hctxs;
1296 struct blk_mq_ctx *ctx;
1297 struct request_queue *q;
1300 if (!reg->nr_hw_queues ||
1301 !reg->ops->queue_rq || !reg->ops->map_queue ||
1302 !reg->ops->alloc_hctx || !reg->ops->free_hctx)
1303 return ERR_PTR(-EINVAL);
1305 if (!reg->queue_depth)
1306 reg->queue_depth = BLK_MQ_MAX_DEPTH;
1307 else if (reg->queue_depth > BLK_MQ_MAX_DEPTH) {
1308 pr_err("blk-mq: queuedepth too large (%u)\n", reg->queue_depth);
1309 reg->queue_depth = BLK_MQ_MAX_DEPTH;
1313 * Set aside a tag for flush requests. It will only be used while
1314 * another flush request is in progress but outside the driver.
1316 * TODO: only allocate if flushes are supported
1319 reg->reserved_tags++;
1321 if (reg->queue_depth < (reg->reserved_tags + BLK_MQ_TAG_MIN))
1322 return ERR_PTR(-EINVAL);
1324 ctx = alloc_percpu(struct blk_mq_ctx);
1326 return ERR_PTR(-ENOMEM);
1328 hctxs = kmalloc_node(reg->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
1334 for (i = 0; i < reg->nr_hw_queues; i++) {
1335 hctxs[i] = reg->ops->alloc_hctx(reg, i);
1339 hctxs[i]->numa_node = NUMA_NO_NODE;
1340 hctxs[i]->queue_num = i;
1343 q = blk_alloc_queue_node(GFP_KERNEL, reg->numa_node);
1347 q->mq_map = blk_mq_make_queue_map(reg);
1351 setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
1352 blk_queue_rq_timeout(q, 30000);
1354 q->nr_queues = nr_cpu_ids;
1355 q->nr_hw_queues = reg->nr_hw_queues;
1358 q->queue_hw_ctx = hctxs;
1360 q->mq_ops = reg->ops;
1361 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
1363 blk_queue_make_request(q, blk_mq_make_request);
1364 blk_queue_rq_timed_out(q, reg->ops->timeout);
1366 blk_queue_rq_timeout(q, reg->timeout);
1368 blk_mq_init_flush(q);
1369 blk_mq_init_cpu_queues(q, reg->nr_hw_queues);
1371 if (blk_mq_init_hw_queues(q, reg, driver_data))
1374 blk_mq_map_swqueue(q);
1376 mutex_lock(&all_q_mutex);
1377 list_add_tail(&q->all_q_node, &all_q_list);
1378 mutex_unlock(&all_q_mutex);
1384 blk_cleanup_queue(q);
1386 for (i = 0; i < reg->nr_hw_queues; i++) {
1389 reg->ops->free_hctx(hctxs[i], i);
1394 return ERR_PTR(-ENOMEM);
1396 EXPORT_SYMBOL(blk_mq_init_queue);
1398 void blk_mq_free_queue(struct request_queue *q)
1400 struct blk_mq_hw_ctx *hctx;
1403 queue_for_each_hw_ctx(q, hctx, i) {
1404 kfree(hctx->ctx_map);
1406 blk_mq_free_rq_map(hctx);
1407 blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1408 if (q->mq_ops->exit_hctx)
1409 q->mq_ops->exit_hctx(hctx, i);
1410 q->mq_ops->free_hctx(hctx, i);
1413 free_percpu(q->queue_ctx);
1414 kfree(q->queue_hw_ctx);
1417 q->queue_ctx = NULL;
1418 q->queue_hw_ctx = NULL;
1421 mutex_lock(&all_q_mutex);
1422 list_del_init(&q->all_q_node);
1423 mutex_unlock(&all_q_mutex);
1426 /* Basically redo blk_mq_init_queue with queue frozen */
1427 static void blk_mq_queue_reinit(struct request_queue *q)
1429 blk_mq_freeze_queue(q);
1431 blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues);
1434 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
1435 * we should change hctx numa_node according to new topology (this
1436 * involves free and re-allocate memory, worthy doing?)
1439 blk_mq_map_swqueue(q);
1441 blk_mq_unfreeze_queue(q);
1444 static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
1445 unsigned long action, void *hcpu)
1447 struct request_queue *q;
1450 * Before new mapping is established, hotadded cpu might already start
1451 * handling requests. This doesn't break anything as we map offline
1452 * CPUs to first hardware queue. We will re-init queue below to get
1455 if (action != CPU_DEAD && action != CPU_DEAD_FROZEN &&
1456 action != CPU_ONLINE && action != CPU_ONLINE_FROZEN)
1459 mutex_lock(&all_q_mutex);
1460 list_for_each_entry(q, &all_q_list, all_q_node)
1461 blk_mq_queue_reinit(q);
1462 mutex_unlock(&all_q_mutex);
1466 static int __init blk_mq_init(void)
1470 /* Must be called after percpu_counter_hotcpu_callback() */
1471 hotcpu_notifier(blk_mq_queue_reinit_notify, -10);
1475 subsys_initcall(blk_mq_init);