diff options
| author | Darrick J. Wong <darrick.wong@oracle.com> | 2015-02-13 11:05:37 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-03-18 14:11:07 +0100 |
| commit | 144ab376d2c0342dc0caa050b078a1d9ebb04a9d (patch) | |
| tree | 5c284917b3aea16bf61e76a9f03edfcba8d19153 /drivers/md | |
| parent | 5eb2654c6829c2e5dc8f8d4d641b93148bcca300 (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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-io.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c index c09359db3a90..37de0173b6d2 100644 --- a/drivers/md/dm-io.c +++ b/drivers/md/dm-io.c @@ -290,6 +290,12 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where, unsigned short logical_block_size = queue_logical_block_size(q); sector_t num_sectors; + /* Reject unsupported discard requests */ + if ((rw & REQ_DISCARD) && !blk_queue_discard(q)) { + dec_count(io, region, -EOPNOTSUPP); + return; + } + /* * where->count may be zero if rw holds a flush and we need to * send a zero-sized flush. |