Btrfs: fix missing check before creating a qgroup relation

Step to reproduce:
		mkfs.btrfs <disk>
		mount <disk> <mnt>
		btrfs quota enable <mnt>
		btrfs qgroup assign 0/1 1/1 <mnt>
		umount <mnt>
		btrfs-debug-tree <disk> | grep QGROUP
If we want to add a qgroup relation, we should gurantee that
'src' and 'dst' exist, otherwise, such qgroup relation should
not be allowed to create.

Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 49c4e6398f18..0932b839550c 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -954,6 +954,8 @@ int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans,
                               struct btrfs_fs_info *fs_info, u64 src, u64 dst)
 {
         struct btrfs_root *quota_root;
+        struct btrfs_qgroup *parent;
+        struct btrfs_qgroup *member;
         int ret = 0;
 
         mutex_lock(&fs_info->qgroup_ioctl_lock);
@@ -962,6 +964,12 @@ int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans,
                 ret = -EINVAL;
                 goto out;
         }
+        member = find_qgroup_rb(fs_info, src);
+        parent = find_qgroup_rb(fs_info, dst);
+        if (!member || !parent) {
+                ret = -EINVAL;
+                goto out;
+        }
 
         ret = add_qgroup_relation_item(trans, quota_root, src, dst);
         if (ret)