Commit 43a5e4e2 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: blk-mq: support draining mq queue 



blk_mq_drain_queue() is introduced so that we can drain
mq queue inside blk_cleanup_queue().

Also don't accept new requests any more if queue is marked
as dying.

Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarMing Lei <tom.leiming@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent b28bc9b3

block/blk-core.c

+8 −2
Original line number Diff line number Diff line
@@ -38,6 +38,7 @@ 


#include "blk.h"

#include "blk-cgroup.h"

#include "blk-mq.h"



EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);

EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
@@ -497,8 +498,13 @@ void blk_cleanup_queue(struct request_queue *q) 
	 * Drain all requests queued before DYING marking. Set DEAD flag to

	 * prevent that q->request_fn() gets invoked after draining finished.

	 */

	if (q->mq_ops) {

		blk_mq_drain_queue(q);

		spin_lock_irq(lock);

	} else {

		spin_lock_irq(lock);

		__blk_drain_queue(q, true);

	}

	queue_flag_set(QUEUE_FLAG_DEAD, q);

	spin_unlock_irq(lock);

block/blk-exec.c

+4 −0
Original line number Diff line number Diff line
@@ -60,6 +60,10 @@ void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk, 
	rq->rq_disk = bd_disk;

	rq->end_io = done;



	/*

	 * don't check dying flag for MQ because the request won't

	 * be resued after dying flag is set

	 */

	if (q->mq_ops) {

		blk_mq_insert_request(q, rq, true);

		return;

block/blk-mq.c

+27 −16
Original line number Diff line number Diff line
@@ -106,10 +106,13 @@ static int blk_mq_queue_enter(struct request_queue *q) 


	spin_lock_irq(q->queue_lock);

	ret = wait_event_interruptible_lock_irq(q->mq_freeze_wq,

		!blk_queue_bypass(q), *q->queue_lock);

		!blk_queue_bypass(q) || blk_queue_dying(q),

		*q->queue_lock);

	/* inc usage with lock hold to avoid freeze_queue runs here */

	if (!ret)

	if (!ret && !blk_queue_dying(q))

		__percpu_counter_add(&q->mq_usage_counter, 1, 1000000);

	else if (blk_queue_dying(q))

		ret = -ENODEV;

	spin_unlock_irq(q->queue_lock);



	return ret;
@@ -120,6 +123,22 @@ static void blk_mq_queue_exit(struct request_queue *q) 
	__percpu_counter_add(&q->mq_usage_counter, -1, 1000000);

}



static void __blk_mq_drain_queue(struct request_queue *q)

{

	while (true) {

		s64 count;



		spin_lock_irq(q->queue_lock);

		count = percpu_counter_sum(&q->mq_usage_counter);

		spin_unlock_irq(q->queue_lock);



		if (count == 0)

			break;

		blk_mq_run_queues(q, false);

		msleep(10);

	}

}



/*

 * Guarantee no request is in use, so we can change any data structure of

 * the queue afterward.
@@ -133,21 +152,13 @@ static void blk_mq_freeze_queue(struct request_queue *q) 
	queue_flag_set(QUEUE_FLAG_BYPASS, q);

	spin_unlock_irq(q->queue_lock);



	if (!drain)

		return;



	while (true) {

		s64 count;



		spin_lock_irq(q->queue_lock);

		count = percpu_counter_sum(&q->mq_usage_counter);

		spin_unlock_irq(q->queue_lock);



		if (count == 0)

			break;

		blk_mq_run_queues(q, false);

		msleep(10);

	if (drain)

		__blk_mq_drain_queue(q);

}



void blk_mq_drain_queue(struct request_queue *q)

{

	__blk_mq_drain_queue(q);

}



static void blk_mq_unfreeze_queue(struct request_queue *q)

block/blk-mq.h

+1 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ void blk_mq_complete_request(struct request *rq, int error); 
void blk_mq_run_request(struct request *rq, bool run_queue, bool async);

void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);

void blk_mq_init_flush(struct request_queue *q);

void blk_mq_drain_queue(struct request_queue *q);



/*

 * CPU hotplug helpers