diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index bd4555fbdf25..019a009e73a0 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -4935,14 +4935,22 @@ int nfs4_init_session(struct nfs_server *server)
 {
 	struct nfs_client *clp = server->nfs_client;
 	struct nfs4_session *session;
+	unsigned int rsize, wsize;
 	int ret;
 
 	if (!nfs4_has_session(clp))
 		return 0;
 
+	rsize = server->rsize;
+	if (rsize == 0)
+		rsize = NFS_MAX_FILE_IO_SIZE;
+	wsize = server->wsize;
+	if (wsize == 0)
+		wsize = NFS_MAX_FILE_IO_SIZE;
+
 	session = clp->cl_session;
-	session->fc_attrs.max_rqst_sz = server->wsize + nfs41_maxwrite_overhead;
-	session->fc_attrs.max_resp_sz = server->rsize + nfs41_maxread_overhead;
+	session->fc_attrs.max_rqst_sz = wsize + nfs41_maxwrite_overhead;
+	session->fc_attrs.max_resp_sz = rsize + nfs41_maxread_overhead;
 
 	ret = nfs4_recover_expired_lease(server);
 	if (!ret)