[XFS] add helper to get xfs_inode from vnode

SGI-PV: 947206
SGI-Modid: xfs-linux-melb:xfs-kern:203960a

Signed-off-by: Christoph Hellwig <hch@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
diff --git a/fs/xfs/linux-2.6/xfs_iops.c b/fs/xfs/linux-2.6/xfs_iops.c
index fe5e989..d388d14 100644
--- a/fs/xfs/linux-2.6/xfs_iops.c
+++ b/fs/xfs/linux-2.6/xfs_iops.c
@@ -59,6 +59,22 @@
 	(S_ISDIR(inode->i_mode) && inode->i_sb->s_flags & MS_NODIRATIME))
 
 /*
+ * Get a XFS inode from a given vnode.
+ */
+xfs_inode_t *
+xfs_vtoi(
+	struct vnode	*vp)
+{
+	bhv_desc_t      *bdp;
+
+	bdp = bhv_lookup_range(VN_BHV_HEAD(vp),
+			VNODE_POSITION_XFS, VNODE_POSITION_XFS);
+	if (unlikely(bdp == NULL))
+		return NULL;
+	return XFS_BHVTOI(bdp);
+}
+
+/*
  * Bring the atime in the XFS inode uptodate.
  * Used before logging the inode to disk or when the Linux inode goes away.
  */