NFS: fix nfs_fetch_iversion()

The change attribute is always set by all NFS client versions so get rid
of the open-coded version.

Fixes: 3cc55f44 ("nfs: use change attribute for NFS re-exports")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/export.c

@@ -171,17 +171,10 @@ static u64 nfs_fetch_iversion(struct inode *inode)
 {
 	struct nfs_server *server = NFS_SERVER(inode);
 
-	/* Is this the right call?: */
-	nfs_revalidate_inode(server, inode);
-	/*
-	 * Also, note we're ignoring any returned error.  That seems to be
-	 * the practice for cache consistency information elsewhere in
-	 * the server, but I'm not sure why.
-	 */
-	if (server->nfs_client->rpc_ops->version >= 4)
-		return inode_peek_iversion_raw(inode);
-	else
-		return time_to_chattr(&inode->i_ctime);
+	if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_CHANGE |
+						   NFS_INO_REVAL_PAGECACHE))
+		__nfs_revalidate_inode(server, inode);
+	return inode_peek_iversion_raw(inode);
 }
 
 const struct export_operations nfs_export_ops = {