nfsd: unregister with rpcbind when deleting a transport

JIRA: https://issues.redhat.com/browse/RHEL-115855
Conflicts: include/linux/sunrpc/svc_xprt.h - context difference because
	RHEL9 doesn't have eccbbc7 ("nfsd: don't use sv_nrthreads
	in connection limiting calculations.")

commit 898374f
Author: Olga Kornievskaia <okorniev@redhat.com>
Date:   Tue Aug 19 14:04:02 2025 -0400

    nfsd: unregister with rpcbind when deleting a transport

    When a listener is added, a part of creation of transport also registers
    program/port with rpcbind. However, when the listener is removed,
    while transport goes away, rpcbind still has the entry for that
    port/type.

    When deleting the transport, unregister with rpcbind when appropriate.

    ---v2 created a new xpt_flag XPT_RPCB_UNREG to mark TCP and UDP
    transport and at xprt destroy send rpcbind unregister if flag set.

    Suggested-by: Chuck Lever <chuck.lever@oracle.com>
    Fixes: d093c90 ("nfsd: fix management of listener transports")
    Cc: stable@vger.kernel.org
    Signed-off-by: Olga Kornievskaia <okorniev@redhat.com>
    Reviewed-by: Jeff Layton <jlayton@kernel.org>
    Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Signed-off-by: Scott Mayhew <smayhew@redhat.com>

Author: scottmayhew

include/linux/sunrpc/svc_xprt.h

@@ -99,6 +99,9 @@ enum {
 	XPT_HANDSHAKE,		/* xprt requests a handshake */
 	XPT_TLS_SESSION,	/* transport-layer security established */
 	XPT_PEER_AUTH,		/* peer has been authenticated */
+	XPT_RPCB_UNREG,		/* transport that needs unregistering
+				 * with rpcbind (TCP, UDP) on destroy
+				 */
 };
 
 static inline void unregister_xpt_user(struct svc_xprt *xpt, struct svc_xpt_user *u)

net/sunrpc/svc_xprt.c

@@ -1038,6 +1038,19 @@ static void svc_delete_xprt(struct svc_xprt *xprt)
 	struct svc_serv	*serv = xprt->xpt_server;
 	struct svc_deferred_req *dr;
 
+	/* unregister with rpcbind for when transport type is TCP or UDP.
+	 */
+	if (test_bit(XPT_RPCB_UNREG, &xprt->xpt_flags)) {
+		struct svc_sock *svsk = container_of(xprt, struct svc_sock,
+						     sk_xprt);
+		struct socket *sock = svsk->sk_sock;
+
+		if (svc_register(serv, xprt->xpt_net, sock->sk->sk_family,
+				 sock->sk->sk_protocol, 0) < 0)
+			pr_warn("failed to unregister %s with rpcbind\n",
+				xprt->xpt_class->xcl_name);
+	}
+
 	if (test_and_set_bit(XPT_DEAD, &xprt->xpt_flags))
 		return;
 

net/sunrpc/svcsock.c

@@ -836,6 +836,7 @@ static void svc_udp_init(struct svc_sock *svsk, struct svc_serv *serv)
 	/* data might have come in before data_ready set up */
 	set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);
 	set_bit(XPT_CHNGBUF, &svsk->sk_xprt.xpt_flags);
+	set_bit(XPT_RPCB_UNREG, &svsk->sk_xprt.xpt_flags);
 
 	/* make sure we get destination address info */
 	switch (svsk->sk_sk->sk_family) {
@@ -1406,6 +1407,7 @@ static void svc_tcp_init(struct svc_sock *svsk, struct svc_serv *serv)
 	if (sk->sk_state == TCP_LISTEN) {
 		strcpy(svsk->sk_xprt.xpt_remotebuf, "listener");
 		set_bit(XPT_LISTENER, &svsk->sk_xprt.xpt_flags);
+		set_bit(XPT_RPCB_UNREG, &svsk->sk_xprt.xpt_flags);
 		sk->sk_data_ready = svc_tcp_listen_data_ready;
 		set_bit(XPT_CONN, &svsk->sk_xprt.xpt_flags);
 	} else {