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Commit a8ac51e4 authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm rq: add DM_MAPIO_DELAY_REQUEUE to delay requeue of blk-mq requests 



Otherwise blk-mq will immediately dispatch requests that are requeued
via a BLK_MQ_RQ_QUEUE_BUSY return from blk_mq_ops .queue_rq.

Delayed requeue is implemented using blk_mq_delay_kick_requeue_list()
with a delay of 5 secs.  In the context of DM multipath (all paths down)
it doesn't make any sense to requeue more quickly.

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 9f4c3f87

drivers/md/dm-rq.c

+18 −14
Original line number Diff line number Diff line
@@ -336,20 +336,21 @@ static void dm_old_requeue_request(struct request *rq) 
	spin_unlock_irqrestore(q->queue_lock, flags);

}



static void dm_mq_requeue_request(struct request *rq)

static void dm_mq_delay_requeue_request(struct request *rq, unsigned long msecs)

{

	struct request_queue *q = rq->q;

	unsigned long flags;



	blk_mq_requeue_request(rq);



	spin_lock_irqsave(q->queue_lock, flags);

	if (!blk_queue_stopped(q))

		blk_mq_kick_requeue_list(q);

		blk_mq_delay_kick_requeue_list(q, msecs);

	spin_unlock_irqrestore(q->queue_lock, flags);

}



static void dm_requeue_original_request(struct mapped_device *md,

					struct request *rq)

					struct request *rq, bool delay_requeue)

{

	int rw = rq_data_dir(rq);
@@ -359,7 +360,7 @@ static void dm_requeue_original_request(struct mapped_device *md, 
	if (!rq->q->mq_ops)

		dm_old_requeue_request(rq);

	else

		dm_mq_requeue_request(rq);

		dm_mq_delay_requeue_request(rq, delay_requeue ? 5000 : 0);



	rq_completed(md, rw, false);

}
@@ -389,7 +390,7 @@ static void dm_done(struct request *clone, int error, bool mapped) 
		return;

	else if (r == DM_ENDIO_REQUEUE)

		/* The target wants to requeue the I/O */

		dm_requeue_original_request(tio->md, tio->orig);

		dm_requeue_original_request(tio->md, tio->orig, false);

	else {

		DMWARN("unimplemented target endio return value: %d", r);

		BUG();
@@ -629,8 +630,8 @@ static int dm_old_prep_fn(struct request_queue *q, struct request *rq) 


/*

 * Returns:

 * 0                : the request has been processed

 * DM_MAPIO_REQUEUE : the original request needs to be requeued

 * DM_MAPIO_*       : the request has been processed as indicated

 * DM_MAPIO_REQUEUE : the original request needs to be immediately requeued

 * < 0              : the request was completed due to failure

 */

static int map_request(struct dm_rq_target_io *tio, struct request *rq,
@@ -643,6 +644,8 @@ static int map_request(struct dm_rq_target_io *tio, struct request *rq, 
	if (tio->clone) {

		clone = tio->clone;

		r = ti->type->map_rq(ti, clone, &tio->info);

		if (r == DM_MAPIO_DELAY_REQUEUE)

			return DM_MAPIO_REQUEUE; /* .request_fn requeue is always immediate */

	} else {

		r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);

		if (r < 0) {
@@ -650,9 +653,8 @@ static int map_request(struct dm_rq_target_io *tio, struct request *rq, 
			dm_kill_unmapped_request(rq, r);

			return r;

		}

		if (r != DM_MAPIO_REMAPPED)

			return r;

		if (setup_clone(clone, rq, tio, GFP_ATOMIC)) {

		if (r == DM_MAPIO_REMAPPED &&

		    setup_clone(clone, rq, tio, GFP_ATOMIC)) {

			/* -ENOMEM */

			ti->type->release_clone_rq(clone);

			return DM_MAPIO_REQUEUE;
@@ -671,7 +673,10 @@ static int map_request(struct dm_rq_target_io *tio, struct request *rq, 
		break;

	case DM_MAPIO_REQUEUE:

		/* The target wants to requeue the I/O */

		dm_requeue_original_request(md, tio->orig);

		break;

	case DM_MAPIO_DELAY_REQUEUE:

		/* The target wants to requeue the I/O after a delay */

		dm_requeue_original_request(md, tio->orig, true);

		break;

	default:

		if (r > 0) {
@@ -681,10 +686,9 @@ static int map_request(struct dm_rq_target_io *tio, struct request *rq, 


		/* The target wants to complete the I/O */

		dm_kill_unmapped_request(rq, r);

		return r;

	}



	return 0;

	return r;

}



static void dm_start_request(struct mapped_device *md, struct request *orig)
@@ -727,7 +731,7 @@ static void map_tio_request(struct kthread_work *work) 
	struct mapped_device *md = tio->md;



	if (map_request(tio, rq, md) == DM_MAPIO_REQUEUE)

		dm_requeue_original_request(md, rq);

		dm_requeue_original_request(md, rq, false);

}



ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf)

include/linux/device-mapper.h

+1 −0
Original line number Diff line number Diff line
@@ -590,6 +590,7 @@ extern struct ratelimit_state dm_ratelimit_state; 
#define DM_MAPIO_SUBMITTED	0

#define DM_MAPIO_REMAPPED	1

#define DM_MAPIO_REQUEUE	DM_ENDIO_REQUEUE

#define DM_MAPIO_DELAY_REQUEUE	3



#define dm_sector_div64(x, y)( \

{ \