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author | Darrick J. Wong <darrick.wong@oracle.com> | 2015-02-13 11:05:37 -0800 |
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committer | Jiri Slaby <jslaby@suse.cz> | 2015-03-16 14:58:17 +0100 |
commit | d5a590350fc031273762482cc0d46a6c4a8220b3 (patch) | |
tree | 2a070545f1a9540317639c3505a974fcb42dab05 /drivers/md/Makefile | |
parent | 9bc83b500a3d2d59e09956755ce271e00f71a335 (diff) |
dm io: reject unsupported DISCARD requests with EOPNOTSUPP
commit 37527b869207ad4c208b1e13967d69b8bba1fbf9 upstream.
I created a dm-raid1 device backed by a device that supports DISCARD
and another device that does NOT support DISCARD with the following
dm configuration:
# echo '0 2048 mirror core 1 512 2 /dev/sda 0 /dev/sdb 0' | dmsetup create moo
# lsblk -D
NAME DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO
sda 0 4K 1G 0
`-moo (dm-0) 0 4K 1G 0
sdb 0 0B 0B 0
`-moo (dm-0) 0 4K 1G 0
Notice that the mirror device /dev/mapper/moo advertises DISCARD
support even though one of the mirror halves doesn't.
If I issue a DISCARD request (via fstrim, mount -o discard, or ioctl
BLKDISCARD) through the mirror, kmirrord gets stuck in an infinite
loop in do_region() when it tries to issue a DISCARD request to sdb.
The problem is that when we call do_region() against sdb, num_sectors
is set to zero because q->limits.max_discard_sectors is zero.
Therefore, "remaining" never decreases and the loop never terminates.
To fix this: before entering the loop, check for the combination of
REQ_DISCARD and no discard and return -EOPNOTSUPP to avoid hanging up
the mirror device.
This bug was found by the unfortunate coincidence of pvmove and a
discard operation in the RHEL 6.5 kernel; upstream is also affected.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'drivers/md/Makefile')
0 files changed, 0 insertions, 0 deletions