From: Heinz Mauelshagen Date: Wed, 29 Oct 2014 18:02:27 +0000 (+0100) Subject: dm raid: fix inaccessible superblocks causing oops in configure_discard_support X-Git-Tag: firefly_0821_release~176^2~2776^2~51 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d20c4b08be822ab1c5d333297f38f1b532d3febc;p=firefly-linux-kernel-4.4.55.git 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 --- diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c index a7cb9dd5f135..07c0fa0fa284 100644 --- a/drivers/md/dm-raid.c +++ b/drivers/md/dm-raid.c @@ -1172,8 +1172,12 @@ static void configure_discard_support(struct dm_target *ti, struct raid_set *rs) 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;