RDMA/iwcm: Allow AFONLY binding for IPv6 addresses

Binding IPv6 address/port to AF_INET6 domain only is provided via
rdma_set_afonly(), but was not signalled to the provider. Applications
like NFS/RDMA bind the same port to both IPv4 and IPv6 addresses
simultaneously and thus rely on it working correctly.

Link: https://lore.kernel.org/r/[e-mail]
Tested-by: Chuck Lever <[e-mail]>
Tested-by: Benjamin Coddington <[e-mail]>
Signed-off-by: Bernard Metzler <[e-mail]>
Signed-off-by: Jason Gunthorpe <[e-mail]>

drivers/infiniband/core/cma.c

···
 
 	id->tos = id_priv->tos;
 	id->tos_set = id_priv->tos_set;
+	id->afonly = id_priv->afonly;
 	id_priv->cm_id.iw = id;
 
 	memcpy(&id_priv->cm_id.iw->local_addr, cma_src_addr(id_priv),

drivers/infiniband/sw/siw/siw_cm.c

···
 }
 
 static int kernel_bindconnect(struct socket *s, struct sockaddr *laddr,
-			      struct sockaddr *raddr)
+			      struct sockaddr *raddr, bool afonly)
 {
 	int rv, flags = 0;
 	size_t size = laddr->sa_family == AF_INET ?
···
 	 * Make address available again asap.
 	 */
 	sock_set_reuseaddr(s->sk);
+
+	if (afonly) {
+		rv = ip6_sock_set_v6only(s->sk);
+		if (rv)
+			return rv;
+	}
 
 	rv = s->ops->bind(s, laddr, size);
 	if (rv < 0)
···
 	 * mode. Might be reconsidered for async connection setup at
 	 * TCP level.
 	 */
-	rv = kernel_bindconnect(s, laddr, raddr);
+	rv = kernel_bindconnect(s, laddr, raddr, id->afonly);
 	if (rv != 0) {
 		siw_dbg_qp(qp, "kernel_bindconnect: error %d\n", rv);
 		goto error;
···
 				  sizeof(struct sockaddr_in));
 	} else {
 		struct sockaddr_in6 *laddr = &to_sockaddr_in6(id->local_addr);
+
+		if (id->afonly) {
+			rv = ip6_sock_set_v6only(s->sk);
+			if (rv) {
+				siw_dbg(id->device,
+					"ip6_sock_set_v6only erro: %d\n", rv);
+				goto error;
+			}
+		}
 
 		/* For wildcard addr, limit binding to current device only */
 		if (ipv6_addr_any(&laddr->sin6_addr))

include/rdma/iw_cm.h

···
 	u8  tos;
 	bool tos_set:1;
 	bool mapped:1;
+	bool afonly:1;
 };
 
 struct iw_cm_conn_param {