block: Make blk_mq_delay_kick_requeue_list() rerun the queue at a quiet time

The blk_mq_delay_kick_requeue_list() function is used by the device
mapper and only by the device mapper to rerun the queue and requeue
list after a delay. This function is called once per request that
gets requeued. Modify this function such that the queue is run once
per path change event instead of once per request that is requeued.

Fixes: commit 2849450a ("blk-mq: introduce blk_mq_delay_kick_requeue_list()")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

@@ -684,7 +684,7 @@ EXPORT_SYMBOL(blk_mq_kick_requeue_list);
 void blk_mq_delay_kick_requeue_list(struct request_queue *q,
 				    unsigned long msecs)
 {
-	kblockd_schedule_delayed_work(&q->requeue_work,
+	kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
 				    msecs_to_jiffies(msecs));
 }
 EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);