SUNRPC: Allow further customisation of RPC program registration

Add a callback to allow customisation of the rpcbind registration.
When clients have the ability to turn on and off version support,
we want to allow them to also prevent registration of those
versions with the rpc portmapper.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/lockd/svc.c

@@ -809,4 +809,5 @@ static struct svc_program	nlmsvc_program = {
 	.pg_stats		= &nlmsvc_stats,	/* stats table */
 	.pg_authenticate	= &lockd_authenticate,	/* export authentication */
 	.pg_init_request	= svc_generic_init_request,
+	.pg_rpcbind_set		= svc_generic_rpcbind_set,
 };

fs/nfs/callback.c

@@ -458,4 +458,5 @@ static struct svc_program nfs4_callback_program = {
 	.pg_stats = &nfs4_callback_stats,
 	.pg_authenticate = nfs_callback_authenticate,
 	.pg_init_request = svc_generic_init_request,
+	.pg_rpcbind_set	= svc_generic_rpcbind_set,
 };

fs/nfsd/nfssvc.c

@@ -87,6 +87,7 @@ static struct svc_program	nfsd_acl_program = {
 	.pg_stats		= &nfsd_acl_svcstats,
 	.pg_authenticate	= &svc_set_client,
 	.pg_init_request	= svc_generic_init_request,
+	.pg_rpcbind_set		= svc_generic_rpcbind_set,
 };
 
 static struct svc_stat	nfsd_acl_svcstats = {
@@ -120,7 +121,7 @@ struct svc_program		nfsd_program = {
 	.pg_stats		= &nfsd_svcstats,	/* version table */
 	.pg_authenticate	= &svc_set_client,	/* export authentication */
 	.pg_init_request	= svc_generic_init_request,
-
+	.pg_rpcbind_set		= svc_generic_rpcbind_set,
 };
 
 static bool nfsd_supported_minorversions[NFSD_SUPPORTED_MINOR_VERSION + 1] = {

include/linux/sunrpc/svc.h

@@ -410,6 +410,11 @@ struct svc_program {
 	__be32			(*pg_init_request)(struct svc_rqst *,
 						   const struct svc_program *,
 						   struct svc_process_info *);
+	int			(*pg_rpcbind_set)(struct net *net,
+						  const struct svc_program *,
+						  u32 version, int family,
+						  unsigned short proto,
+						  unsigned short port);
 };
 
 /*
@@ -522,6 +527,16 @@ __be32		   svc_return_autherr(struct svc_rqst *rqstp, __be32 auth_err);
 __be32		   svc_generic_init_request(struct svc_rqst *rqstp,
 					    const struct svc_program *progp,
 					    struct svc_process_info *procinfo);
+int		   svc_generic_rpcbind_set(struct net *net,
+					   const struct svc_program *progp,
+					   u32 version, int family,
+					   unsigned short proto,
+					   unsigned short port);
+int		   svc_rpcbind_set_version(struct net *net,
+					   const struct svc_program *progp,
+					   u32 version, int family,
+					   unsigned short proto,
+					   unsigned short port);
 
 #define	RPC_MAX_ADDRBUFLEN	(63U)
 

net/sunrpc/svc.c

@@ -993,6 +993,58 @@ static int __svc_register(struct net *net, const char *progname,
 	return error;
 }
 
+int svc_rpcbind_set_version(struct net *net,
+			    const struct svc_program *progp,
+			    u32 version, int family,
+			    unsigned short proto,
+			    unsigned short port)
+{
+	dprintk("svc: svc_register(%sv%d, %s, %u, %u)\n",
+		progp->pg_name, version,
+		proto == IPPROTO_UDP?  "udp" : "tcp",
+		port, family);
+
+	return __svc_register(net, progp->pg_name, progp->pg_prog,
+				version, family, proto, port);
+
+}
+EXPORT_SYMBOL_GPL(svc_rpcbind_set_version);
+
+int svc_generic_rpcbind_set(struct net *net,
+			    const struct svc_program *progp,
+			    u32 version, int family,
+			    unsigned short proto,
+			    unsigned short port)
+{
+	const struct svc_version *vers = progp->pg_vers[version];
+	int error;
+
+	if (vers == NULL)
+		return 0;
+
+	if (vers->vs_hidden) {
+		dprintk("svc: svc_register(%sv%d, %s, %u, %u)"
+			" (but not telling portmap)\n",
+			progp->pg_name, version,
+			proto == IPPROTO_UDP?  "udp" : "tcp",
+			port, family);
+		return 0;
+	}
+
+	/*
+	 * Don't register a UDP port if we need congestion
+	 * control.
+	 */
+	if (vers->vs_need_cong_ctrl && proto == IPPROTO_UDP)
+		return 0;
+
+	error = svc_rpcbind_set_version(net, progp, version,
+					family, proto, port);
+
+	return (vers->vs_rpcb_optnl) ? 0 : error;
+}
+EXPORT_SYMBOL_GPL(svc_generic_rpcbind_set);
+
 /**
  * svc_register - register an RPC service with the local portmapper
  * @serv: svc_serv struct for the service to register
@@ -1008,7 +1060,6 @@ int svc_register(const struct svc_serv *serv, struct net *net,
 		 const unsigned short port)
 {
 	struct svc_program	*progp;
-	const struct svc_version *vers;
 	unsigned int		i;
 	int			error = 0;
 
@@ -1018,37 +1069,9 @@ int svc_register(const struct svc_serv *serv, struct net *net,
 
 	for (progp = serv->sv_program; progp; progp = progp->pg_next) {
 		for (i = 0; i < progp->pg_nvers; i++) {
-			vers = progp->pg_vers[i];
-			if (vers == NULL)
-				continue;
-
-			dprintk("svc: svc_register(%sv%d, %s, %u, %u)%s\n",
-					progp->pg_name,
-					i,
-					proto == IPPROTO_UDP?  "udp" : "tcp",
-					port,
-					family,
-					vers->vs_hidden ?
-					" (but not telling portmap)" : "");
-
-			if (vers->vs_hidden)
-				continue;
-
-			/*
-			 * Don't register a UDP port if we need congestion
-			 * control.
-			 */
-			if (vers->vs_need_cong_ctrl && proto == IPPROTO_UDP)
-				continue;
-
-			error = __svc_register(net, progp->pg_name, progp->pg_prog,
-						i, family, proto, port);
-
-			if (vers->vs_rpcb_optnl) {
-				error = 0;
-				continue;
-			}
 
+			error = progp->pg_rpcbind_set(net, progp, i,
+					family, proto, port);
 			if (error < 0) {
 				printk(KERN_WARNING "svc: failed to register "
 					"%sv%u RPC service (errno %d).\n",