[PATCH v2] svcrdma: add IPv6 support

[Shirley Ma <shirley.ma@oracle.com>]

Add rdma6 option to support NFS/RDMA IPv6.
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)

Signed-off-by: Shirley Ma <shirley.ma@oracle.com>
---

diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -869,7 +869,7 @@ 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);
 	}
@@ -885,6 +885,16 @@ 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);