[PATCH 6.1 007/197] btrfs: forbid deleting live subvol qgroup

Greg Kroah-Hartman
2024-02-20T20:59:41Z

From: Boris Burkov <boris@bur.io>

commit a8df35619948bd8363d330c20a90c9a7fbff28c0 upstream.

If a subvolume still exists, forbid deleting its qgroup 0/subvolid.
This behavior generally leads to incorrect behavior in squotas and
doesn't have a legitimate purpose.

Fixes: cecbb533b5fc ("btrfs: record simple quota deltas in delayed refs")
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/qgroup.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1635,6 +1635,15 @@ out:
return ret;
}

+static bool qgroup_has_usage(struct btrfs_qgroup *qgroup)
+{
+ return (qgroup->rfer > 0 || qgroup->rfer_cmpr > 0 ||
+ qgroup->excl > 0 || qgroup->excl_cmpr > 0 ||
+ qgroup->rsv.values[BTRFS_QGROUP_RSV_DATA] > 0 ||
+ qgroup->rsv.values[BTRFS_QGROUP_RSV_META_PREALLOC] > 0 ||
+ qgroup->rsv.values[BTRFS_QGROUP_RSV_META_PERTRANS] > 0);
+}
+
int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
@@ -1654,6 +1663,11 @@ int btrfs_remove_qgroup(struct btrfs_tra
goto out;
}

+ if (is_fstree(qgroupid) && qgroup_has_usage(qgroup)) {
+ ret = -EBUSY;
+ goto out;
+ }
+
/* Check if there are no children of this qgroup */
if (!list_empty(&qgroup->members)) {
ret = -EBUSY;