[XFS] Avoid directly referencing the VFS inode.

In several places we directly convert from the XFS inode
to the linux (VFS) inode by a simple deference of ip->i_vnode.
We should not do this - a helper function should be used to
extract the VFS inode from the XFS inode.

Introduce the function VFS_I() to extract the VFS inode
from the XFS inode. The name was chosen to match XFS_I() which
is used to extract the XFS inode from the VFS inode.

SGI-PV: 981498

SGI-Modid: xfs-linux-melb:xfs-kern:31720a

Signed-off-by: David Chinner <david@fromorbit.com>
Signed-off-by: Niv Sardi <xaiki@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 17a04b6..4a5e48c 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -263,6 +263,25 @@
 #define XFS_ISIZE(ip)	(((ip)->i_d.di_mode & S_IFMT) == S_IFREG) ? \
 				(ip)->i_size : (ip)->i_d.di_size;
 
+/* Convert from vfs inode to xfs inode */
+static inline struct xfs_inode *XFS_I(struct inode *inode)
+{
+	return (struct xfs_inode *)inode->i_private;
+}
+
+static inline struct xfs_inode *xfs_vtoi(bhv_vnode_t *vp)
+{
+	return XFS_I((struct inode *)vp);
+}
+
+/* convert from xfs inode to vfs inode */
+static inline struct inode *VFS_I(struct xfs_inode *ip)
+{
+	return (struct inode *)ip->i_vnode;
+}
+#define	XFS_ITOV(ip)		VFS_I(ip)
+#define	XFS_ITOV_NULL(ip)	VFS_I(ip)
+
 /*
  * i_flags helper functions
  */
@@ -439,9 +458,6 @@
 #define	XFS_ITRUNC_DEFINITE	0x1
 #define	XFS_ITRUNC_MAYBE	0x2
 
-#define	XFS_ITOV(ip)		((ip)->i_vnode)
-#define	XFS_ITOV_NULL(ip)	((ip)->i_vnode)
-
 /*
  * For multiple groups support: if S_ISGID bit is set in the parent
  * directory, group of new file is set to that of the parent, and