[PATCH] md: clean out unplug and other queue function on md shutdown

The mddev and queue might be used for another array which does not set these,
so they need to be cleared.
Signed-off-by: NNeilBrown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/md/md.c

@@ -3322,6 +3322,9 @@ static int do_md_stop(mddev_t * mddev, int mode)
 				set_disk_ro(disk, 0);
 			blk_queue_make_request(mddev->queue, md_fail_request);
 			mddev->pers->stop(mddev);
+			mddev->queue->merge_bvec_fn = NULL;
+			mddev->queue->unplug_fn = NULL;
+			mddev->queue->issue_flush_fn = NULL;
 			if (mddev->pers->sync_request)
 				sysfs_remove_group(&mddev->kobj, &md_redundancy_group);