[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_inode_item.c b/fs/xfs/xfs_inode_item.c
index 7f3363c..9369010 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -271,6 +271,11 @@
 	if (ip->i_update_size)
 		ip->i_update_size = 0;
 
+	/*
+	 * Make sure to get the latest atime from the Linux inode.
+	 */
+	xfs_synchronize_atime(ip);
+
 	vecp->i_addr = (xfs_caddr_t)&ip->i_d;
 	vecp->i_len  = sizeof(xfs_dinode_core_t);
 	XLOG_VEC_SET_TYPE(vecp, XLOG_REG_TYPE_ICORE);