nfsd: set timeparms.to_maxval in setup_callback_client

...otherwise the logic in the timeout handling doesn't work correctly.
Spotted-by: NTrond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4callback.c

@@ -654,9 +654,11 @@ static struct rpc_clnt *create_backchannel_client(struct rpc_create_args *args)
 
 static int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *conn, struct nfsd4_session *ses)
 {
+	int maxtime = max_cb_time(clp->net);
 	struct rpc_timeout	timeparms = {
-		.to_initval	= max_cb_time(clp->net),
+		.to_initval	= maxtime,
 		.to_retries	= 0,
+		.to_maxval	= maxtime,
 	};
 	struct rpc_create_args args = {
 		.net		= clp->net,