[PATCH] md: make sure recovery happens when add_new_disk is used for hot_add

Currently if add_new_disk is used to hot-add a drive to a degraded array,
recovery doesn't start ...  because we didn't tell it to.
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/md/md.c

@@ -2083,6 +2083,8 @@ static int add_new_disk(mddev_t * mddev, mdu_disk_info_t *info)
 		err = bind_rdev_to_array(rdev, mddev);
 		if (err)
 			export_rdev(rdev);
+
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 		if (mddev->thread)
 			md_wakeup_thread(mddev->thread);
 		return err;