btrfs: Check qgroup level in kernel qgroup assign.

Although we have qgroup level check in btrfs-progs, it's not enough
since other programe may still call ioctl directly not using
btrfs-progs. For example, systemd.

But it's btrfs-progs to be blame since we don't provide a
full-function(like subvolume create things) btrfs library with enough
check, and only rely on kernel ioctl.

So Add level checks in kernel too.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 464d1e237512..4fb9610beec7 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1009,6 +1009,10 @@ int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans,
         struct btrfs_qgroup_list *list;
         int ret = 0;
 
+        /* Check the level of src and dst first */
+        if (btrfs_qgroup_level(src) >= btrfs_qgroup_level(dst))
+                return -EINVAL;
+
         mutex_lock(&fs_info->qgroup_ioctl_lock);
         quota_root = fs_info->quota_root;
         if (!quota_root) {