[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/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 30ae963..b497229 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -1106,7 +1106,7 @@
 xfs_flush_inode(
 	xfs_inode_t	*ip)
 {
-	struct inode	*inode = ip->i_vnode;
+	struct inode	*inode = VFS_I(ip);
 
 	igrab(inode);
 	xfs_syncd_queue_work(ip->i_mount, inode, xfs_flush_inode_work);
@@ -1825,7 +1825,7 @@
 	sb->s_time_gran = 1;
 	set_posix_acl_flag(sb);
 
-	root = igrab(mp->m_rootip->i_vnode);
+	root = igrab(VFS_I(mp->m_rootip));
 	if (!root) {
 		error = ENOENT;
 		goto fail_unmount;