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,
201 bool is_flush = false;
203 * flush need allocate a request, leave at least one request for
204 * non-flush IO to avoid deadlock
206 if ((rw & REQ_FLUSH) && !(rw & REQ_FLUSH_SEQ)) {
207 if (atomic_inc_return(&hctx->pending_flush) >=
208 hctx->queue_depth - hctx->reserved_tags - 1) {
209 atomic_dec(&hctx->pending_flush);
214 req = blk_mq_alloc_rq(hctx, gfp, reserved);
215 if (!req && is_flush)
216 atomic_dec(&hctx->pending_flush);
220 static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
227 struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
228 struct blk_mq_hw_ctx *hctx = q->mq_ops->map_queue(q, ctx->cpu);
230 rq = __blk_mq_alloc_request(hctx, gfp & ~__GFP_WAIT, reserved, rw);
232 blk_mq_rq_ctx_init(q, ctx, rq, rw);
237 if (!(gfp & __GFP_WAIT))
240 __blk_mq_run_hw_queue(hctx);
241 blk_mq_wait_for_tags(hctx->tags);
247 struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
248 gfp_t gfp, bool reserved)
252 if (blk_mq_queue_enter(q))
255 rq = blk_mq_alloc_request_pinned(q, rw, gfp, reserved);
257 blk_mq_put_ctx(rq->mq_ctx);
261 struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
266 if (blk_mq_queue_enter(q))
269 rq = blk_mq_alloc_request_pinned(q, rw, gfp, true);
271 blk_mq_put_ctx(rq->mq_ctx);
274 EXPORT_SYMBOL(blk_mq_alloc_reserved_request);
277 * Re-init and set pdu, if we have it
279 static void blk_mq_rq_init(struct blk_mq_hw_ctx *hctx, struct request *rq)
281 blk_rq_init(hctx->queue, rq);
284 rq->special = blk_mq_rq_to_pdu(rq);
287 static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
288 struct blk_mq_ctx *ctx, struct request *rq)
290 const int tag = rq->tag;
291 struct request_queue *q = rq->q;
293 if ((rq->cmd_flags & REQ_FLUSH) && !(rq->cmd_flags & REQ_FLUSH_SEQ))
294 atomic_dec(&hctx->pending_flush);
296 blk_mq_rq_init(hctx, rq);
297 blk_mq_put_tag(hctx->tags, tag);
299 blk_mq_queue_exit(q);
302 void blk_mq_free_request(struct request *rq)
304 struct blk_mq_ctx *ctx = rq->mq_ctx;
305 struct blk_mq_hw_ctx *hctx;
306 struct request_queue *q = rq->q;
308 ctx->rq_completed[rq_is_sync(rq)]++;
310 hctx = q->mq_ops->map_queue(q, ctx->cpu);
311 __blk_mq_free_request(hctx, ctx, rq);
314 static void blk_mq_bio_endio(struct request *rq, struct bio *bio, int error)
317 clear_bit(BIO_UPTODATE, &bio->bi_flags);
318 else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
321 if (unlikely(rq->cmd_flags & REQ_QUIET))
322 set_bit(BIO_QUIET, &bio->bi_flags);
324 /* don't actually finish bio if it's part of flush sequence */
325 if (!(rq->cmd_flags & REQ_FLUSH_SEQ))
326 bio_endio(bio, error);
329 void blk_mq_complete_request(struct request *rq, int error)
331 struct bio *bio = rq->bio;
332 unsigned int bytes = 0;
334 trace_block_rq_complete(rq->q, rq);
337 struct bio *next = bio->bi_next;
340 bytes += bio->bi_iter.bi_size;
341 blk_mq_bio_endio(rq, bio, error);
345 blk_account_io_completion(rq, bytes);
347 blk_account_io_done(rq);
350 rq->end_io(rq, error);
352 blk_mq_free_request(rq);
355 void __blk_mq_end_io(struct request *rq, int error)
357 if (!blk_mark_rq_complete(rq))
358 blk_mq_complete_request(rq, error);
361 static void blk_mq_end_io_remote(void *data)
363 struct request *rq = data;
365 __blk_mq_end_io(rq, rq->errors);
369 * End IO on this request on a multiqueue enabled driver. We'll either do
370 * it directly inline, or punt to a local IPI handler on the matching
373 void blk_mq_end_io(struct request *rq, int error)
375 struct blk_mq_ctx *ctx = rq->mq_ctx;
378 if (!ctx->ipi_redirect)
379 return __blk_mq_end_io(rq, error);
382 if (cpu != ctx->cpu && cpu_online(ctx->cpu)) {
384 rq->csd.func = blk_mq_end_io_remote;
387 __smp_call_function_single(ctx->cpu, &rq->csd, 0);
389 __blk_mq_end_io(rq, error);
393 EXPORT_SYMBOL(blk_mq_end_io);
395 static void blk_mq_start_request(struct request *rq)
397 struct request_queue *q = rq->q;
399 trace_block_rq_issue(q, rq);
402 * Just mark start time and set the started bit. Due to memory
403 * ordering, we know we'll see the correct deadline as long as
404 * REQ_ATOMIC_STARTED is seen.
406 rq->deadline = jiffies + q->rq_timeout;
407 set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
410 static void blk_mq_requeue_request(struct request *rq)
412 struct request_queue *q = rq->q;
414 trace_block_rq_requeue(q, rq);
415 clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
418 struct blk_mq_timeout_data {
419 struct blk_mq_hw_ctx *hctx;
421 unsigned int *next_set;
424 static void blk_mq_timeout_check(void *__data, unsigned long *free_tags)
426 struct blk_mq_timeout_data *data = __data;
427 struct blk_mq_hw_ctx *hctx = data->hctx;
430 /* It may not be in flight yet (this is where
431 * the REQ_ATOMIC_STARTED flag comes in). The requests are
432 * statically allocated, so we know it's always safe to access the
433 * memory associated with a bit offset into ->rqs[].
439 tag = find_next_zero_bit(free_tags, hctx->queue_depth, tag);
440 if (tag >= hctx->queue_depth)
443 rq = hctx->rqs[tag++];
445 if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
448 blk_rq_check_expired(rq, data->next, data->next_set);
452 static void blk_mq_hw_ctx_check_timeout(struct blk_mq_hw_ctx *hctx,
454 unsigned int *next_set)
456 struct blk_mq_timeout_data data = {
459 .next_set = next_set,
463 * Ask the tagging code to iterate busy requests, so we can
464 * check them for timeout.
466 blk_mq_tag_busy_iter(hctx->tags, blk_mq_timeout_check, &data);
469 static void blk_mq_rq_timer(unsigned long data)
471 struct request_queue *q = (struct request_queue *) data;
472 struct blk_mq_hw_ctx *hctx;
473 unsigned long next = 0;
476 queue_for_each_hw_ctx(q, hctx, i)
477 blk_mq_hw_ctx_check_timeout(hctx, &next, &next_set);
480 mod_timer(&q->timeout, round_jiffies_up(next));
484 * Reverse check our software queue for entries that we could potentially
485 * merge with. Currently includes a hand-wavy stop count of 8, to not spend
486 * too much time checking for merges.
488 static bool blk_mq_attempt_merge(struct request_queue *q,
489 struct blk_mq_ctx *ctx, struct bio *bio)
494 list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
500 if (!blk_rq_merge_ok(rq, bio))
503 el_ret = blk_try_merge(rq, bio);
504 if (el_ret == ELEVATOR_BACK_MERGE) {
505 if (bio_attempt_back_merge(q, rq, bio)) {
510 } else if (el_ret == ELEVATOR_FRONT_MERGE) {
511 if (bio_attempt_front_merge(q, rq, bio)) {
522 void blk_mq_add_timer(struct request *rq)
524 __blk_add_timer(rq, NULL);
528 * Run this hardware queue, pulling any software queues mapped to it in.
529 * Note that this function currently has various problems around ordering
530 * of IO. In particular, we'd like FIFO behaviour on handling existing
531 * items on the hctx->dispatch list. Ignore that for now.
533 static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
535 struct request_queue *q = hctx->queue;
536 struct blk_mq_ctx *ctx;
541 if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->flags)))
547 * Touch any software queue that has pending entries.
549 for_each_set_bit(bit, hctx->ctx_map, hctx->nr_ctx) {
550 clear_bit(bit, hctx->ctx_map);
551 ctx = hctx->ctxs[bit];
552 BUG_ON(bit != ctx->index_hw);
554 spin_lock(&ctx->lock);
555 list_splice_tail_init(&ctx->rq_list, &rq_list);
556 spin_unlock(&ctx->lock);
560 * If we have previous entries on our dispatch list, grab them
561 * and stuff them at the front for more fair dispatch.
563 if (!list_empty_careful(&hctx->dispatch)) {
564 spin_lock(&hctx->lock);
565 if (!list_empty(&hctx->dispatch))
566 list_splice_init(&hctx->dispatch, &rq_list);
567 spin_unlock(&hctx->lock);
571 * Delete and return all entries from our dispatch list
576 * Now process all the entries, sending them to the driver.
578 while (!list_empty(&rq_list)) {
581 rq = list_first_entry(&rq_list, struct request, queuelist);
582 list_del_init(&rq->queuelist);
583 blk_mq_start_request(rq);
585 if (q->dma_drain_size && blk_rq_bytes(rq)) {
587 * make sure space for the drain appears we
588 * know we can do this because max_hw_segments
589 * has been adjusted to be one fewer than the
592 rq->nr_phys_segments++;
596 * Last request in the series. Flag it as such, this
597 * enables drivers to know when IO should be kicked off,
598 * if they don't do it on a per-request basis.
600 * Note: the flag isn't the only condition drivers
601 * should do kick off. If drive is busy, the last
602 * request might not have the bit set.
604 if (list_empty(&rq_list))
605 rq->cmd_flags |= REQ_END;
607 ret = q->mq_ops->queue_rq(hctx, rq);
609 case BLK_MQ_RQ_QUEUE_OK:
612 case BLK_MQ_RQ_QUEUE_BUSY:
614 * FIXME: we should have a mechanism to stop the queue
615 * like blk_stop_queue, otherwise we will waste cpu
618 list_add(&rq->queuelist, &rq_list);
619 blk_mq_requeue_request(rq);
622 pr_err("blk-mq: bad return on queue: %d\n", ret);
624 case BLK_MQ_RQ_QUEUE_ERROR:
625 blk_mq_end_io(rq, rq->errors);
629 if (ret == BLK_MQ_RQ_QUEUE_BUSY)
634 hctx->dispatched[0]++;
635 else if (queued < (1 << (BLK_MQ_MAX_DISPATCH_ORDER - 1)))
636 hctx->dispatched[ilog2(queued) + 1]++;
639 * Any items that need requeuing? Stuff them into hctx->dispatch,
640 * that is where we will continue on next queue run.
642 if (!list_empty(&rq_list)) {
643 spin_lock(&hctx->lock);
644 list_splice(&rq_list, &hctx->dispatch);
645 spin_unlock(&hctx->lock);
649 void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
651 if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->flags)))
655 __blk_mq_run_hw_queue(hctx);
657 struct request_queue *q = hctx->queue;
659 kblockd_schedule_delayed_work(q, &hctx->delayed_work, 0);
663 void blk_mq_run_queues(struct request_queue *q, bool async)
665 struct blk_mq_hw_ctx *hctx;
668 queue_for_each_hw_ctx(q, hctx, i) {
669 if ((!blk_mq_hctx_has_pending(hctx) &&
670 list_empty_careful(&hctx->dispatch)) ||
671 test_bit(BLK_MQ_S_STOPPED, &hctx->flags))
674 blk_mq_run_hw_queue(hctx, async);
677 EXPORT_SYMBOL(blk_mq_run_queues);
679 void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
681 cancel_delayed_work(&hctx->delayed_work);
682 set_bit(BLK_MQ_S_STOPPED, &hctx->state);
684 EXPORT_SYMBOL(blk_mq_stop_hw_queue);
686 void blk_mq_stop_hw_queues(struct request_queue *q)
688 struct blk_mq_hw_ctx *hctx;
691 queue_for_each_hw_ctx(q, hctx, i)
692 blk_mq_stop_hw_queue(hctx);
694 EXPORT_SYMBOL(blk_mq_stop_hw_queues);
696 void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
698 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
699 __blk_mq_run_hw_queue(hctx);
701 EXPORT_SYMBOL(blk_mq_start_hw_queue);
703 void blk_mq_start_stopped_hw_queues(struct request_queue *q)
705 struct blk_mq_hw_ctx *hctx;
708 queue_for_each_hw_ctx(q, hctx, i) {
709 if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
712 clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
713 blk_mq_run_hw_queue(hctx, true);
716 EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
718 static void blk_mq_work_fn(struct work_struct *work)
720 struct blk_mq_hw_ctx *hctx;
722 hctx = container_of(work, struct blk_mq_hw_ctx, delayed_work.work);
723 __blk_mq_run_hw_queue(hctx);
726 static void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx,
727 struct request *rq, bool at_head)
729 struct blk_mq_ctx *ctx = rq->mq_ctx;
731 trace_block_rq_insert(hctx->queue, rq);
734 list_add(&rq->queuelist, &ctx->rq_list);
736 list_add_tail(&rq->queuelist, &ctx->rq_list);
737 blk_mq_hctx_mark_pending(hctx, ctx);
740 * We do this early, to ensure we are on the right CPU.
742 blk_mq_add_timer(rq);
745 void blk_mq_insert_request(struct request_queue *q, struct request *rq,
746 bool at_head, bool run_queue)
748 struct blk_mq_hw_ctx *hctx;
749 struct blk_mq_ctx *ctx, *current_ctx;
752 hctx = q->mq_ops->map_queue(q, ctx->cpu);
754 if (rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
755 blk_insert_flush(rq);
757 current_ctx = blk_mq_get_ctx(q);
759 if (!cpu_online(ctx->cpu)) {
761 hctx = q->mq_ops->map_queue(q, ctx->cpu);
764 spin_lock(&ctx->lock);
765 __blk_mq_insert_request(hctx, rq, at_head);
766 spin_unlock(&ctx->lock);
768 blk_mq_put_ctx(current_ctx);
772 __blk_mq_run_hw_queue(hctx);
774 EXPORT_SYMBOL(blk_mq_insert_request);
777 * This is a special version of blk_mq_insert_request to bypass FLUSH request
778 * check. Should only be used internally.
780 void blk_mq_run_request(struct request *rq, bool run_queue, bool async)
782 struct request_queue *q = rq->q;
783 struct blk_mq_hw_ctx *hctx;
784 struct blk_mq_ctx *ctx, *current_ctx;
786 current_ctx = blk_mq_get_ctx(q);
789 if (!cpu_online(ctx->cpu)) {
793 hctx = q->mq_ops->map_queue(q, ctx->cpu);
795 /* ctx->cpu might be offline */
796 spin_lock(&ctx->lock);
797 __blk_mq_insert_request(hctx, rq, false);
798 spin_unlock(&ctx->lock);
800 blk_mq_put_ctx(current_ctx);
803 blk_mq_run_hw_queue(hctx, async);
806 static void blk_mq_insert_requests(struct request_queue *q,
807 struct blk_mq_ctx *ctx,
808 struct list_head *list,
813 struct blk_mq_hw_ctx *hctx;
814 struct blk_mq_ctx *current_ctx;
816 trace_block_unplug(q, depth, !from_schedule);
818 current_ctx = blk_mq_get_ctx(q);
820 if (!cpu_online(ctx->cpu))
822 hctx = q->mq_ops->map_queue(q, ctx->cpu);
825 * preemption doesn't flush plug list, so it's possible ctx->cpu is
828 spin_lock(&ctx->lock);
829 while (!list_empty(list)) {
832 rq = list_first_entry(list, struct request, queuelist);
833 list_del_init(&rq->queuelist);
835 __blk_mq_insert_request(hctx, rq, false);
837 spin_unlock(&ctx->lock);
839 blk_mq_put_ctx(current_ctx);
841 blk_mq_run_hw_queue(hctx, from_schedule);
844 static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
846 struct request *rqa = container_of(a, struct request, queuelist);
847 struct request *rqb = container_of(b, struct request, queuelist);
849 return !(rqa->mq_ctx < rqb->mq_ctx ||
850 (rqa->mq_ctx == rqb->mq_ctx &&
851 blk_rq_pos(rqa) < blk_rq_pos(rqb)));
854 void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
856 struct blk_mq_ctx *this_ctx;
857 struct request_queue *this_q;
863 list_splice_init(&plug->mq_list, &list);
865 list_sort(NULL, &list, plug_ctx_cmp);
871 while (!list_empty(&list)) {
872 rq = list_entry_rq(list.next);
873 list_del_init(&rq->queuelist);
875 if (rq->mq_ctx != this_ctx) {
877 blk_mq_insert_requests(this_q, this_ctx,
882 this_ctx = rq->mq_ctx;
888 list_add_tail(&rq->queuelist, &ctx_list);
892 * If 'this_ctx' is set, we know we have entries to complete
893 * on 'ctx_list'. Do those.
896 blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
901 static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
903 init_request_from_bio(rq, bio);
904 blk_account_io_start(rq, 1);
907 static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
909 struct blk_mq_hw_ctx *hctx;
910 struct blk_mq_ctx *ctx;
911 const int is_sync = rw_is_sync(bio->bi_rw);
912 const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
913 int rw = bio_data_dir(bio);
915 unsigned int use_plug, request_count = 0;
918 * If we have multiple hardware queues, just go directly to
919 * one of those for sync IO.
921 use_plug = !is_flush_fua && ((q->nr_hw_queues == 1) || !is_sync);
923 blk_queue_bounce(q, &bio);
925 if (use_plug && blk_attempt_plug_merge(q, bio, &request_count))
928 if (blk_mq_queue_enter(q)) {
929 bio_endio(bio, -EIO);
933 ctx = blk_mq_get_ctx(q);
934 hctx = q->mq_ops->map_queue(q, ctx->cpu);
936 trace_block_getrq(q, bio, rw);
937 rq = __blk_mq_alloc_request(hctx, GFP_ATOMIC, false, bio->bi_rw);
939 blk_mq_rq_ctx_init(q, ctx, rq, bio->bi_rw);
942 trace_block_sleeprq(q, bio, rw);
943 rq = blk_mq_alloc_request_pinned(q, bio->bi_rw,
944 __GFP_WAIT|GFP_ATOMIC, false);
946 hctx = q->mq_ops->map_queue(q, ctx->cpu);
951 if (unlikely(is_flush_fua)) {
952 blk_mq_bio_to_request(rq, bio);
954 blk_insert_flush(rq);
959 * A task plug currently exists. Since this is completely lockless,
960 * utilize that to temporarily store requests until the task is
961 * either done or scheduled away.
964 struct blk_plug *plug = current->plug;
967 blk_mq_bio_to_request(rq, bio);
968 if (list_empty(&plug->mq_list))
970 else if (request_count >= BLK_MAX_REQUEST_COUNT) {
971 blk_flush_plug_list(plug, false);
974 list_add_tail(&rq->queuelist, &plug->mq_list);
980 spin_lock(&ctx->lock);
982 if ((hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
983 blk_mq_attempt_merge(q, ctx, bio))
984 __blk_mq_free_request(hctx, ctx, rq);
986 blk_mq_bio_to_request(rq, bio);
987 __blk_mq_insert_request(hctx, rq, false);
990 spin_unlock(&ctx->lock);
994 * For a SYNC request, send it to the hardware immediately. For an
995 * ASYNC request, just ensure that we run it later on. The latter
996 * allows for merging opportunities and more efficient dispatching.
999 blk_mq_run_hw_queue(hctx, !is_sync || is_flush_fua);
1003 * Default mapping to a software queue, since we use one per CPU.
1005 struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q, const int cpu)
1007 return q->queue_hw_ctx[q->mq_map[cpu]];
1009 EXPORT_SYMBOL(blk_mq_map_queue);
1011 struct blk_mq_hw_ctx *blk_mq_alloc_single_hw_queue(struct blk_mq_reg *reg,
1012 unsigned int hctx_index)
1014 return kmalloc_node(sizeof(struct blk_mq_hw_ctx),
1015 GFP_KERNEL | __GFP_ZERO, reg->numa_node);
1017 EXPORT_SYMBOL(blk_mq_alloc_single_hw_queue);
1019 void blk_mq_free_single_hw_queue(struct blk_mq_hw_ctx *hctx,
1020 unsigned int hctx_index)
1024 EXPORT_SYMBOL(blk_mq_free_single_hw_queue);
1026 static void blk_mq_hctx_notify(void *data, unsigned long action,
1029 struct blk_mq_hw_ctx *hctx = data;
1030 struct blk_mq_ctx *ctx;
1033 if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
1037 * Move ctx entries to new CPU, if this one is going away.
1039 ctx = __blk_mq_get_ctx(hctx->queue, cpu);
1041 spin_lock(&ctx->lock);
1042 if (!list_empty(&ctx->rq_list)) {
1043 list_splice_init(&ctx->rq_list, &tmp);
1044 clear_bit(ctx->index_hw, hctx->ctx_map);
1046 spin_unlock(&ctx->lock);
1048 if (list_empty(&tmp))
1051 ctx = blk_mq_get_ctx(hctx->queue);
1052 spin_lock(&ctx->lock);
1054 while (!list_empty(&tmp)) {
1057 rq = list_first_entry(&tmp, struct request, queuelist);
1059 list_move_tail(&rq->queuelist, &ctx->rq_list);
1062 blk_mq_hctx_mark_pending(hctx, ctx);
1064 spin_unlock(&ctx->lock);
1065 blk_mq_put_ctx(ctx);
1068 static void blk_mq_init_hw_commands(struct blk_mq_hw_ctx *hctx,
1069 void (*init)(void *, struct blk_mq_hw_ctx *,
1070 struct request *, unsigned int),
1075 for (i = 0; i < hctx->queue_depth; i++) {
1076 struct request *rq = hctx->rqs[i];
1078 init(data, hctx, rq, i);
1082 void blk_mq_init_commands(struct request_queue *q,
1083 void (*init)(void *, struct blk_mq_hw_ctx *,
1084 struct request *, unsigned int),
1087 struct blk_mq_hw_ctx *hctx;
1090 queue_for_each_hw_ctx(q, hctx, i)
1091 blk_mq_init_hw_commands(hctx, init, data);
1093 EXPORT_SYMBOL(blk_mq_init_commands);
1095 static void blk_mq_free_rq_map(struct blk_mq_hw_ctx *hctx)
1099 while (!list_empty(&hctx->page_list)) {
1100 page = list_first_entry(&hctx->page_list, struct page, lru);
1101 list_del_init(&page->lru);
1102 __free_pages(page, page->private);
1108 blk_mq_free_tags(hctx->tags);
1111 static size_t order_to_size(unsigned int order)
1113 size_t ret = PAGE_SIZE;
1121 static int blk_mq_init_rq_map(struct blk_mq_hw_ctx *hctx,
1122 unsigned int reserved_tags, int node)
1124 unsigned int i, j, entries_per_page, max_order = 4;
1125 size_t rq_size, left;
1127 INIT_LIST_HEAD(&hctx->page_list);
1129 hctx->rqs = kmalloc_node(hctx->queue_depth * sizeof(struct request *),
1135 * rq_size is the size of the request plus driver payload, rounded
1136 * to the cacheline size
1138 rq_size = round_up(sizeof(struct request) + hctx->cmd_size,
1140 left = rq_size * hctx->queue_depth;
1142 for (i = 0; i < hctx->queue_depth;) {
1143 int this_order = max_order;
1148 while (left < order_to_size(this_order - 1) && this_order)
1152 page = alloc_pages_node(node, GFP_KERNEL, this_order);
1157 if (order_to_size(this_order) < rq_size)
1164 page->private = this_order;
1165 list_add_tail(&page->lru, &hctx->page_list);
1167 p = page_address(page);
1168 entries_per_page = order_to_size(this_order) / rq_size;
1169 to_do = min(entries_per_page, hctx->queue_depth - i);
1170 left -= to_do * rq_size;
1171 for (j = 0; j < to_do; j++) {
1173 blk_mq_rq_init(hctx, hctx->rqs[i]);
1179 if (i < (reserved_tags + BLK_MQ_TAG_MIN))
1181 else if (i != hctx->queue_depth) {
1182 hctx->queue_depth = i;
1183 pr_warn("%s: queue depth set to %u because of low memory\n",
1187 hctx->tags = blk_mq_init_tags(hctx->queue_depth, reserved_tags, node);
1190 blk_mq_free_rq_map(hctx);
1197 static int blk_mq_init_hw_queues(struct request_queue *q,
1198 struct blk_mq_reg *reg, void *driver_data)
1200 struct blk_mq_hw_ctx *hctx;
1204 * Initialize hardware queues
1206 queue_for_each_hw_ctx(q, hctx, i) {
1207 unsigned int num_maps;
1210 node = hctx->numa_node;
1211 if (node == NUMA_NO_NODE)
1212 node = hctx->numa_node = reg->numa_node;
1214 INIT_DELAYED_WORK(&hctx->delayed_work, blk_mq_work_fn);
1215 spin_lock_init(&hctx->lock);
1216 INIT_LIST_HEAD(&hctx->dispatch);
1218 hctx->queue_num = i;
1219 hctx->flags = reg->flags;
1220 hctx->queue_depth = reg->queue_depth;
1221 hctx->reserved_tags = reg->reserved_tags;
1222 hctx->cmd_size = reg->cmd_size;
1223 atomic_set(&hctx->pending_flush, 0);
1225 blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
1226 blk_mq_hctx_notify, hctx);
1227 blk_mq_register_cpu_notifier(&hctx->cpu_notifier);
1229 if (blk_mq_init_rq_map(hctx, reg->reserved_tags, node))
1233 * Allocate space for all possible cpus to avoid allocation in
1236 hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
1241 num_maps = ALIGN(nr_cpu_ids, BITS_PER_LONG) / BITS_PER_LONG;
1242 hctx->ctx_map = kzalloc_node(num_maps * sizeof(unsigned long),
1247 hctx->nr_ctx_map = num_maps;
1250 if (reg->ops->init_hctx &&
1251 reg->ops->init_hctx(hctx, driver_data, i))
1255 if (i == q->nr_hw_queues)
1261 queue_for_each_hw_ctx(q, hctx, j) {
1265 if (reg->ops->exit_hctx)
1266 reg->ops->exit_hctx(hctx, j);
1268 blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1269 blk_mq_free_rq_map(hctx);
1276 static void blk_mq_init_cpu_queues(struct request_queue *q,
1277 unsigned int nr_hw_queues)
1281 for_each_possible_cpu(i) {
1282 struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
1283 struct blk_mq_hw_ctx *hctx;
1285 memset(__ctx, 0, sizeof(*__ctx));
1287 spin_lock_init(&__ctx->lock);
1288 INIT_LIST_HEAD(&__ctx->rq_list);
1291 /* If the cpu isn't online, the cpu is mapped to first hctx */
1292 hctx = q->mq_ops->map_queue(q, i);
1299 * Set local node, IFF we have more than one hw queue. If
1300 * not, we remain on the home node of the device
1302 if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
1303 hctx->numa_node = cpu_to_node(i);
1307 static void blk_mq_map_swqueue(struct request_queue *q)
1310 struct blk_mq_hw_ctx *hctx;
1311 struct blk_mq_ctx *ctx;
1313 queue_for_each_hw_ctx(q, hctx, i) {
1318 * Map software to hardware queues
1320 queue_for_each_ctx(q, ctx, i) {
1321 /* If the cpu isn't online, the cpu is mapped to first hctx */
1322 hctx = q->mq_ops->map_queue(q, i);
1323 ctx->index_hw = hctx->nr_ctx;
1324 hctx->ctxs[hctx->nr_ctx++] = ctx;
1328 struct request_queue *blk_mq_init_queue(struct blk_mq_reg *reg,
1331 struct blk_mq_hw_ctx **hctxs;
1332 struct blk_mq_ctx *ctx;
1333 struct request_queue *q;
1336 if (!reg->nr_hw_queues ||
1337 !reg->ops->queue_rq || !reg->ops->map_queue ||
1338 !reg->ops->alloc_hctx || !reg->ops->free_hctx)
1339 return ERR_PTR(-EINVAL);
1341 if (!reg->queue_depth)
1342 reg->queue_depth = BLK_MQ_MAX_DEPTH;
1343 else if (reg->queue_depth > BLK_MQ_MAX_DEPTH) {
1344 pr_err("blk-mq: queuedepth too large (%u)\n", reg->queue_depth);
1345 reg->queue_depth = BLK_MQ_MAX_DEPTH;
1348 if (reg->queue_depth < (reg->reserved_tags + BLK_MQ_TAG_MIN))
1349 return ERR_PTR(-EINVAL);
1351 ctx = alloc_percpu(struct blk_mq_ctx);
1353 return ERR_PTR(-ENOMEM);
1355 hctxs = kmalloc_node(reg->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
1361 for (i = 0; i < reg->nr_hw_queues; i++) {
1362 hctxs[i] = reg->ops->alloc_hctx(reg, i);
1366 hctxs[i]->numa_node = NUMA_NO_NODE;
1367 hctxs[i]->queue_num = i;
1370 q = blk_alloc_queue_node(GFP_KERNEL, reg->numa_node);
1374 q->mq_map = blk_mq_make_queue_map(reg);
1378 setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
1379 blk_queue_rq_timeout(q, 30000);
1381 q->nr_queues = nr_cpu_ids;
1382 q->nr_hw_queues = reg->nr_hw_queues;
1385 q->queue_hw_ctx = hctxs;
1387 q->mq_ops = reg->ops;
1388 q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
1390 q->sg_reserved_size = INT_MAX;
1392 blk_queue_make_request(q, blk_mq_make_request);
1393 blk_queue_rq_timed_out(q, reg->ops->timeout);
1395 blk_queue_rq_timeout(q, reg->timeout);
1397 blk_mq_init_flush(q);
1398 blk_mq_init_cpu_queues(q, reg->nr_hw_queues);
1400 if (blk_mq_init_hw_queues(q, reg, driver_data))
1403 blk_mq_map_swqueue(q);
1405 mutex_lock(&all_q_mutex);
1406 list_add_tail(&q->all_q_node, &all_q_list);
1407 mutex_unlock(&all_q_mutex);
1413 blk_cleanup_queue(q);
1415 for (i = 0; i < reg->nr_hw_queues; i++) {
1418 reg->ops->free_hctx(hctxs[i], i);
1423 return ERR_PTR(-ENOMEM);
1425 EXPORT_SYMBOL(blk_mq_init_queue);
1427 void blk_mq_free_queue(struct request_queue *q)
1429 struct blk_mq_hw_ctx *hctx;
1432 queue_for_each_hw_ctx(q, hctx, i) {
1433 kfree(hctx->ctx_map);
1435 blk_mq_free_rq_map(hctx);
1436 blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
1437 if (q->mq_ops->exit_hctx)
1438 q->mq_ops->exit_hctx(hctx, i);
1439 q->mq_ops->free_hctx(hctx, i);
1442 free_percpu(q->queue_ctx);
1443 kfree(q->queue_hw_ctx);
1446 q->queue_ctx = NULL;
1447 q->queue_hw_ctx = NULL;
1450 mutex_lock(&all_q_mutex);
1451 list_del_init(&q->all_q_node);
1452 mutex_unlock(&all_q_mutex);
1455 /* Basically redo blk_mq_init_queue with queue frozen */
1456 static void blk_mq_queue_reinit(struct request_queue *q)
1458 blk_mq_freeze_queue(q);
1460 blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues);
1463 * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
1464 * we should change hctx numa_node according to new topology (this
1465 * involves free and re-allocate memory, worthy doing?)
1468 blk_mq_map_swqueue(q);
1470 blk_mq_unfreeze_queue(q);
1473 static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
1474 unsigned long action, void *hcpu)
1476 struct request_queue *q;
1479 * Before new mapping is established, hotadded cpu might already start
1480 * handling requests. This doesn't break anything as we map offline
1481 * CPUs to first hardware queue. We will re-init queue below to get
1484 if (action != CPU_DEAD && action != CPU_DEAD_FROZEN &&
1485 action != CPU_ONLINE && action != CPU_ONLINE_FROZEN)
1488 mutex_lock(&all_q_mutex);
1489 list_for_each_entry(q, &all_q_list, all_q_node)
1490 blk_mq_queue_reinit(q);
1491 mutex_unlock(&all_q_mutex);
1495 static int __init blk_mq_init(void)
1499 /* Must be called after percpu_counter_hotcpu_callback() */
1500 hotcpu_notifier(blk_mq_queue_reinit_notify, -10);
1504 subsys_initcall(blk_mq_init);