Mask root object ID into f_fsid in btrfs_statfs()

Date: Mon, 18 Aug 2008 13:10:20 +0100
This means that subvolumes get a different fsid, and NFS exporting them
works properly.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 6446ab73f35a..55f4d00fda3a 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -503,6 +503,10 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
            on a big-endian or little-endian host */
         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
+        /* Mask in the root object ID too, to disambiguate subvols */
+        buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
+        buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
+
         return 0;
 }