[XFS] fix, speedup and simplify atime handling	let the VFS handle atime
updates and only sync back to the xfs inode when nessecary

SGI-PV: 946679
SGI-Modid: xfs-linux-melb:xfs-kern:203362a

Signed-off-by: Christoph Hellwig <hch@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index f63646e..41f50e7 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -56,6 +56,7 @@
 {
 	xfs_dinode_core_t *dic;		/* dinode core info pointer */
 	xfs_inode_t	*ip;		/* incore inode pointer */
+	vnode_t		*vp;
 	int		error;
 
 	error = xfs_iget(mp, NULL, ino, 0, XFS_ILOCK_SHARED, &ip, bno);
@@ -72,6 +73,7 @@
 		goto out_iput;
 	}
 
+	vp = XFS_ITOV(ip);
 	dic = &ip->i_d;
 
 	/* xfs_iget returns the following without needing
@@ -84,8 +86,9 @@
 	buf->bs_uid = dic->di_uid;
 	buf->bs_gid = dic->di_gid;
 	buf->bs_size = dic->di_size;
-	buf->bs_atime.tv_sec = dic->di_atime.t_sec;
-	buf->bs_atime.tv_nsec = dic->di_atime.t_nsec;
+	/* atime is only kept uptodate in the Linux inode */
+	buf->bs_atime.tv_sec = vp->v_inode.i_atime.tv_sec;
+	buf->bs_atime.tv_nsec = vp->v_inode.i_atime.tv_nsec;
 	buf->bs_mtime.tv_sec = dic->di_mtime.t_sec;
 	buf->bs_mtime.tv_nsec = dic->di_mtime.t_nsec;
 	buf->bs_ctime.tv_sec = dic->di_ctime.t_sec;