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| author | Mark Fasheh <mfasheh@suse.de> | 2014-08-18 21:01:17 (GMT) |
|---|---|---|
| committer | Chris Mason <clm@fb.com> | 2014-09-17 20:38:19 (GMT) |
| commit | 0b4699dcb65c2cff793210b07f40b98c2d423a43 (patch) | |
| tree | 5acf4f368d2245924049f2f6276e20f43065c5ad | |
| parent | b7831b20f32019b741eb8fe3435c2516e13e0c4a (diff) | |
| download | linux-0b4699dcb65c2cff793210b07f40b98c2d423a43.tar.xz | |
btrfs: don't go readonly on existing qgroup items
btrfs_drop_snapshot() leaves subvolume qgroup items on disk after
completion. This can cause problems with snapshot creation. If a new
snapshot tries to claim the deleted subvolumes id, btrfs will get -EEXIST
from add_qgroup_item() and go read-only. The following commands will
reproduce this problem (assume btrfs is on /dev/sda and is mounted at
/btrfs)
mkfs.btrfs -f /dev/sda
mount -t btrfs /dev/sda /btrfs/
btrfs quota enable /btrfs/
btrfs su sna /btrfs/ /btrfs/snap
btrfs su de /btrfs/snap
sleep 45
umount /btrfs/
mount -t btrfs /dev/sda /btrfs/
We can fix this by catching -EEXIST in add_qgroup_item() and
initializing the existing items. We have the problem of orphaned
relation items being on disk from an old snapshot but that is outside
the scope of this patch.
Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: Chris Mason <clm@fb.com>
| -rw-r--r-- | fs/btrfs/qgroup.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 1e4c6e9..cd9717e 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -551,9 +551,15 @@ static int add_qgroup_item(struct btrfs_trans_handle *trans, key.type = BTRFS_QGROUP_INFO_KEY; key.offset = qgroupid; + /* + * Avoid a transaction abort by catching -EEXIST here. In that + * case, we proceed by re-initializing the existing structure + * on disk. + */ + ret = btrfs_insert_empty_item(trans, quota_root, path, &key, sizeof(*qgroup_info)); - if (ret) + if (ret && ret != -EEXIST) goto out; leaf = path->nodes[0]; @@ -572,7 +578,7 @@ static int add_qgroup_item(struct btrfs_trans_handle *trans, key.type = BTRFS_QGROUP_LIMIT_KEY; ret = btrfs_insert_empty_item(trans, quota_root, path, &key, sizeof(*qgroup_limit)); - if (ret) + if (ret && ret != -EEXIST) goto out; leaf = path->nodes[0]; |