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>
                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;