Commit d20c4b08 authored by Heinz Mauelshagen's avatar Heinz Mauelshagen Committed by Mike Snitzer
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dm raid: fix inaccessible superblocks causing oops in configure_discard_support

Commit 48cf06bc

 ("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: default avatarHeinz Mauelshagen <>
Signed-off-by: default avatarMike Snitzer <>
parent 40d43c4b
......@@ -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)
q = bdev_get_queue(rs->dev[i].rdev.bdev);
if (!q || !blk_queue_discard(q))
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