NFSv4: Call update_changeattr() from _nfs4_proc_open only if a file was created

We don't want to invalidate the directory attribute and data cache unless we
know that a file was created, or the change attribute differs from the one
in our cache.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/nfs4proc.c

@@ -2390,11 +2390,12 @@ static int _nfs4_proc_open(struct nfs4_opendata *data)
 	nfs_fattr_map_and_free_names(server, &data->f_attr);
 
 	if (o_arg->open_flags & O_CREAT) {
-		update_changeattr(dir, &o_res->cinfo);
 		if (o_arg->open_flags & O_EXCL)
 			data->file_created = 1;
 		else if (o_res->cinfo.before != o_res->cinfo.after)
 			data->file_created = 1;
+		if (data->file_created || dir->i_version != o_res->cinfo.after)
+			update_changeattr(dir, &o_res->cinfo);
 	}
 	if ((o_res->rflags & NFS4_OPEN_RESULT_LOCKTYPE_POSIX) == 0)
 		server->caps &= ~NFS_CAP_POSIX_LOCK;