block: blk_delay_queue() should use kblockd workqueue

Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/block/blk-core.c b/block/blk-core.c
index 5e41393..e2bacfa 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -220,7 +220,8 @@
  */
 void blk_delay_queue(struct request_queue *q, unsigned long msecs)
 {
-	schedule_delayed_work(&q->delay_work, msecs_to_jiffies(msecs));
+	queue_delayed_work(kblockd_workqueue, &q->delay_work,
+				msecs_to_jiffies(msecs));
 }
 EXPORT_SYMBOL(blk_delay_queue);