svcrdma: Handle ADDR_CHANGE CM event properly

Sagi tells me that when a bonded device reports an address change,
the consumer must destroy its listener IDs and create new ones.

See commit a032e4f6 ("nvmet-rdma: fix bonding failover possible
NULL deref").
Suggested-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/xprtrdma/svc_rdma_transport.c

@@ -284,17 +284,31 @@ static void handle_connect_req(struct rdma_cm_id *new_cma_id,
  *
  * Return values:
  *     %0: Do not destroy @cma_id
- *     %1: Destroy @cma_id (never returned here)
+ *     %1: Destroy @cma_id
  *
  * NB: There is never a DEVICE_REMOVAL event for INADDR_ANY listeners.
  */
 static int svc_rdma_listen_handler(struct rdma_cm_id *cma_id,
 				   struct rdma_cm_event *event)
 {
+	struct sockaddr *sap = (struct sockaddr *)&cma_id->route.addr.src_addr;
+	struct svcxprt_rdma *cma_xprt = cma_id->context;
+	struct svc_xprt *cma_rdma = &cma_xprt->sc_xprt;
+	struct rdma_cm_id *listen_id;
+
 	switch (event->event) {
 	case RDMA_CM_EVENT_CONNECT_REQUEST:
 		handle_connect_req(cma_id, &event->param.conn);
 		break;
+	case RDMA_CM_EVENT_ADDR_CHANGE:
+		listen_id = svc_rdma_create_listen_id(cma_rdma->xpt_net,
+						      sap, cma_xprt);
+		if (IS_ERR(listen_id)) {
+			pr_err("Listener dead, address change failed for device %s\n",
+				cma_id->device->name);
+		} else
+			cma_xprt->sc_cm_id = listen_id;
+		return 1;
 	default:
 		break;
 	}