Btrfs: deny sys_link across subvolumes.
I rebased Christian Parpart's patch to deny hard link across
subvolumes. Original patch modifies also btrfs_rename, but
I excluded it because we can move across subvolumes now and
it make no problem.
-----------------
Hard link across subvolumes should not allowed in Btrfs.
btrfs_link checks root of 'to' directory is same as root
of 'from' file. If not same, btrfs_link returns -EPERM.
Signed-off-by: TARUISI Hiroaki <taruishi.hiroak@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 168e8c0..da76cad 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4462,6 +4462,10 @@
if (inode->i_nlink == 0)
return -ENOENT;
+ /* do not allow sys_link's with other subvols of the same device */
+ if (root->objectid != BTRFS_I(inode)->root->objectid)
+ return -EPERM;
+
/*
* 1 item for inode ref
* 2 items for dir items