From: TARUISI Hiroaki <taruishi.hiroak@jp.fujitsu.com>
Date: Thu, 12 Nov 2009 07:14:26 +0000 (+0000)
Subject: Btrfs: deny sys_link across subvolumes.
X-Git-Tag: v2.6.33-rc1~7^2~1^2~2
X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=4a8be425a8fb8fbb5d881eb55fa6634c3463b9c9;p=~shefty%2Frdma-dev.git

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 168e8c040aa..da76cad92ec 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4462,6 +4462,10 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
 	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