svcrdma: Support IPv6 with NFS/RDMA

Allow both IPv4 and IPv6 to bind same port at the same time,
restricts use of the IPv6 socket to IPv6 communication.

Changes from v1:
 - Check rdma_set_afonly return value (suggested by Leon Romanovsky)

Changes from v2:
 - Acked-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Shirley Ma <shirley.ma@oracle.com>
Acked-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

net/sunrpc/xprtrdma/svc_rdma_transport.c

@@ -789,7 +789,7 @@ static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
 	int ret;
 
 	dprintk("svcrdma: Creating RDMA socket\n");
-	if (sa->sa_family != AF_INET) {
+	if ((sa->sa_family != AF_INET) && (sa->sa_family != AF_INET6)) {
 		dprintk("svcrdma: Address family %d is not supported.\n", sa->sa_family);
 		return ERR_PTR(-EAFNOSUPPORT);
 	}
@@ -805,6 +805,16 @@ static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
 		goto err0;
 	}
 
+	/* Allow both IPv4 and IPv6 sockets to bind a single port
+	 * at the same time.
+	 */
+#if IS_ENABLED(CONFIG_IPV6)
+	ret = rdma_set_afonly(listen_id, 1);
+	if (ret) {
+		dprintk("svcrdma: rdma_set_afonly failed = %d\n", ret);
+		goto err1;
+	}
+#endif
 	ret = rdma_bind_addr(listen_id, sa);
 	if (ret) {
 		dprintk("svcrdma: rdma_bind_addr failed = %d\n", ret);