dm rq: introduce dm_mq_kick_requeue_list()

Make it possible for a request-based target to kick the DM device's
blk-mq request_queue's requeue_list.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index 8eefc0a..877b8f3 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -336,19 +336,28 @@
 	spin_unlock_irqrestore(q->queue_lock, flags);
 }
 
-static void dm_mq_delay_requeue_request(struct request *rq, unsigned long msecs)
+static void __dm_mq_kick_requeue_list(struct request_queue *q, 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_delay_kick_requeue_list(q, msecs);
 	spin_unlock_irqrestore(q->queue_lock, flags);
 }
 
+void dm_mq_kick_requeue_list(struct mapped_device *md)
+{
+	__dm_mq_kick_requeue_list(dm_get_md_queue(md), 0);
+}
+EXPORT_SYMBOL(dm_mq_kick_requeue_list);
+
+static void dm_mq_delay_requeue_request(struct request *rq, unsigned long msecs)
+{
+	blk_mq_requeue_request(rq);
+	__dm_mq_kick_requeue_list(rq->q, msecs);
+}
+
 static void dm_requeue_original_request(struct dm_rq_target_io *tio, bool delay_requeue)
 {
 	struct mapped_device *md = tio->md;