SUNRPC: Fix up the back channel transmit

Fix up the back channel code to recognise that it has already been
transmitted, so does not need to be called again.
Also ensure that we set req->rq_task.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

net/sunrpc/clnt.c

@@ -1138,7 +1138,6 @@ EXPORT_SYMBOL_GPL(rpc_call_async);
 struct rpc_task *rpc_run_bc_task(struct rpc_rqst *req)
 {
 	struct rpc_task *task;
-	struct xdr_buf *xbufp = &req->rq_snd_buf;
 	struct rpc_task_setup task_setup_data = {
 		.callback_ops = &rpc_default_ops,
 		.flags = RPC_TASK_SOFTCONN |
@@ -1150,14 +1149,7 @@ struct rpc_task *rpc_run_bc_task(struct rpc_rqst *req)
 	 * Create an rpc_task to send the data
 	 */
 	task = rpc_new_task(&task_setup_data);
-	task->tk_rqstp = req;
-
-	/*
-	 * Set up the xdr_buf length.
-	 * This also indicates that the buffer is XDR encoded already.
-	 */
-	xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
-			xbufp->tail[0].iov_len;
+	xprt_init_bc_request(req, task);
 
 	task->tk_action = call_bc_transmit;
 	atomic_inc(&task->tk_count);
@@ -2064,6 +2056,8 @@ call_bc_transmit(struct rpc_task *task)
 
 	if (rpc_task_need_encode(task))
 		xprt_request_enqueue_transmit(task);
+	if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
+		goto out_wakeup;
 
 	if (!xprt_prepare_transmit(task))
 		goto out_retry;
@@ -2073,13 +2067,11 @@ call_bc_transmit(struct rpc_task *task)
 			"error: %d\n", task->tk_status);
 		goto out_done;
 	}
-	if (req->rq_connect_cookie != req->rq_xprt->connect_cookie)
-		req->rq_bytes_sent = 0;
 
 	xprt_transmit(task);
 
 	if (task->tk_status == -EAGAIN)
-		goto out_nospace;
+		goto out_retry;
 
 	xprt_end_transmit(task);
 	dprint_status(task);
@@ -2119,12 +2111,11 @@ call_bc_transmit(struct rpc_task *task)
 			"error: %d\n", task->tk_status);
 		break;
 	}
+out_wakeup:
 	rpc_wake_up_queued_task(&req->rq_xprt->pending, task);
 out_done:
 	task->tk_action = rpc_exit_task;
 	return;
-out_nospace:
-	req->rq_connect_cookie = req->rq_xprt->connect_cookie;
 out_retry:
 	task->tk_status = 0;
 }

net/sunrpc/xprt.c

@@ -1390,6 +1390,12 @@ void xprt_free(struct rpc_xprt *xprt)
 }
 EXPORT_SYMBOL_GPL(xprt_free);
 
+static void
+xprt_init_connect_cookie(struct rpc_rqst *req, struct rpc_xprt *xprt)
+{
+	req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
+}
+
 static __be32
 xprt_alloc_xid(struct rpc_xprt *xprt)
 {
@@ -1418,7 +1424,7 @@ xprt_request_init(struct rpc_task *task)
 	req->rq_xprt    = xprt;
 	req->rq_buffer  = NULL;
 	req->rq_xid	= xprt_alloc_xid(xprt);
-	req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
+	xprt_init_connect_cookie(req, xprt);
 	req->rq_bytes_sent = 0;
 	req->rq_snd_buf.len = 0;
 	req->rq_snd_buf.buflen = 0;
@@ -1552,6 +1558,25 @@ void xprt_release(struct rpc_task *task)
 		xprt_free_bc_request(req);
 }
 
+#ifdef CONFIG_SUNRPC_BACKCHANNEL
+void
+xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task)
+{
+	struct xdr_buf *xbufp = &req->rq_snd_buf;
+
+	task->tk_rqstp = req;
+	req->rq_task = task;
+	xprt_init_connect_cookie(req, req->rq_xprt);
+	/*
+	 * Set up the xdr_buf length.
+	 * This also indicates that the buffer is XDR encoded already.
+	 */
+	xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
+		xbufp->tail[0].iov_len;
+	req->rq_bytes_sent = 0;
+}
+#endif
+
 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
 {
 	kref_init(&xprt->kref);