NFS: tidy up nfs_show_mountd_netid

This function is a bit clumsy, incorrectly producing
",mountproto=" if mountd_protocol is 0 and !showdefaults,
and duplicating the code for reporting "auto".

Tidy it up so that it only makes a single seq_printf() call,
and more obviously does the right thing.

Fixes: ee671b016fbf ("NFS: convert proto= option to use netids rather than a protoname")
Signed-off-by: NeilBrown <[e-mail]>
Signed-off-by: Anna Schumaker <[e-mail]>

fs/nfs/super.c

···
 				  int showdefaults)
 {
 	struct sockaddr *sap = (struct sockaddr *) &nfss->mountd_address;
+	char *proto = NULL;
 
-	seq_printf(m, ",mountproto=");
 	switch (sap->sa_family) {
 	case AF_INET:
 		switch (nfss->mountd_protocol) {
 		case IPPROTO_UDP:
-			seq_printf(m, RPCBIND_NETID_UDP);
+			proto = RPCBIND_NETID_UDP;
 			break;
 		case IPPROTO_TCP:
-			seq_printf(m, RPCBIND_NETID_TCP);
+			proto = RPCBIND_NETID_TCP;
 			break;
-		default:
-			if (showdefaults)
-				seq_printf(m, "auto");
 		}
 		break;
 	case AF_INET6:
 		switch (nfss->mountd_protocol) {
 		case IPPROTO_UDP:
-			seq_printf(m, RPCBIND_NETID_UDP6);
+			proto = RPCBIND_NETID_UDP6;
 			break;
 		case IPPROTO_TCP:
-			seq_printf(m, RPCBIND_NETID_TCP6);
+			proto = RPCBIND_NETID_TCP6;
 			break;
-		default:
-			if (showdefaults)
-				seq_printf(m, "auto");
 		}
 		break;
-	default:
-		if (showdefaults)
-			seq_printf(m, "auto");
 	}
+	if (proto || showdefaults)
+		seq_printf(m, ",mountproto=%s", proto ?: "auto");
 }
 
 static void nfs_show_mountd_options(struct seq_file *m, struct nfs_server *nfss,