From d20c4b08be822ab1c5d333297f38f1b532d3febc Mon Sep 17 00:00:00 2001 From: Heinz Mauelshagen Date: Wed, 29 Oct 2014 19:02:27 +0100 Subject: dm raid: fix inaccessible superblocks causing oops in configure_discard_support Commit 48cf06bc5f ("dm raid: add discard support for RAID levels 4, 5 and 6") did not properly handle missing metadata device(s). A failing read of the superblock causes the metadata and data devices to be removed from the dev array in struct raid_set, setting references to both devices to NULL. configure_discard_support() nonetheless tries to access the data dev unconditionally causing an oops. Signed-off-by: Heinz Mauelshagen Signed-off-by: Mike Snitzer --- drivers/md/dm-raid.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) Index: linux-3.18-rc3/drivers/md/dm-raid.c =================================================================== --- linux-3.18-rc3.orig/drivers/md/dm-raid.c 2014-10-20 16:54:01.000000000 +0200 +++ linux-3.18-rc3/drivers/md/dm-raid.c 2014-11-04 18:27:59.000000000 +0100 @@ -1169,8 +1169,12 @@ static void configure_discard_support(st raid456 = (rs->md.level == 4 || rs->md.level == 5 || rs->md.level == 6); for (i = 0; i < rs->md.raid_disks; i++) { - struct request_queue *q = bdev_get_queue(rs->dev[i].rdev.bdev); + struct request_queue *q; + if (!rs->dev[i].rdev.bdev) + continue; + + q = bdev_get_queue(rs->dev[i].rdev.bdev); if (!q || !blk_queue_discard(q)) return;