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authorMark Fasheh <mfasheh@suse.de>2014-08-18 14:01:17 -0700
committerChris Mason <clm@fb.com>2014-09-17 13:38:19 -0700
commit0b4699dcb65c2cff793210b07f40b98c2d423a43 (patch)
tree5acf4f368d2245924049f2f6276e20f43065c5ad
parentb7831b20f32019b741eb8fe3435c2516e13e0c4a (diff)
downloadlinux-0b4699dcb65c2cff793210b07f40b98c2d423a43.tar.bz2
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.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 1e4c6e95ab55..cd9717ea8c9d 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];