Function read_sb_page may return ERR_PTR(...). Check for it.
Signed-off-by: NVasiliy Kulikov <segooon@gmail.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NNeilBrown <neilb@suse.de>