+/*
+ * Probe a server's mountd service to determine which versions and
+ * transport protocols are supported.
+ *
+ * Returns 1 if the requested service port is unambiguous and pingable;
+ * @pmap is filled in with the version, port, and transport protocol used
+ * during the successful ping. If all three are already specified, simply
+ * return success without an rpcbind query or RPC ping (we may be trying
+ * to mount an NFS service that is not advertised via rpcbind).
+ *
+ * If an error occurs or the requested service isn't available, zero is
+ * returned; rpccreateerr.cf_stat is set to reflect the nature of the error.
+ */
+static int nfs_probe_mntport(const struct sockaddr *sap, const socklen_t salen,
+ struct pmap *pmap)