[PATCH 6.1 005/197] btrfs: forbid creating subvol qgroups

Greg Kroah-Hartman
2024-02-20T20:58:29Z

From: Boris Burkov <boris@bur.io>

commit 0c309d66dacddf8ce939b891d9ead4a8e21ad6f0 upstream.

Creating a qgroup 0/subvolid leads to various races and it isn't
helpful, because you can't specify a subvol id when creating a subvol,
so you can't be sure it will be the right one. Any requirements on the
automatic subvol can be gratified by using a higher level qgroup and the
inheritance parameters of subvol creation.

Fixes: cecbb533b5fc ("btrfs: record simple quota deltas in delayed refs")
CC: stable@vger.kernel.org # 4.14+
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/ioctl.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4695,6 +4695,11 @@ static long btrfs_ioctl_qgroup_create(st
goto out;
}

+ if (sa->create && is_fstree(sa->qgroupid)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
trans = btrfs_join_transaction(root);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);