NFS: Optimise inode attribute cache updates

 Allow nfs_refresh_inode() also to update attributes on the inode if the
 RPC call was sent after the last call to nfs_update_inode().

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index abf890f..faeaad6 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -141,6 +141,7 @@
 	unsigned long		attrtimeo_timestamp;
 	__u64			change_attr;		/* v4 only */
 
+	unsigned long		last_updated;
 	/* "Generation counter" for the attribute cache. This is
 	 * bumped whenever we update the metadata on the
 	 * server.
@@ -319,6 +320,7 @@
 static inline void nfs_fattr_init(struct nfs_fattr *fattr)
 {
 	fattr->valid = 0;
+	fattr->time_start = jiffies;
 }
 
 /*