From 902c58872e1e9a2c146a55b0701c0b26cc5a4b24 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Sat, 1 Sep 2018 17:21:01 -0400
Subject: [PATCH] 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>
---
 include/linux/sunrpc/bc_xprt.h |  1 +
 net/sunrpc/clnt.c              | 19 +++++--------------
 net/sunrpc/xprt.c              | 27 ++++++++++++++++++++++++++-
 3 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/include/linux/sunrpc/bc_xprt.h b/include/linux/sunrpc/bc_xprt.h
index 4397a4824c81..28721cf73ec3 100644
--- a/include/linux/sunrpc/bc_xprt.h
+++ b/include/linux/sunrpc/bc_xprt.h
@@ -34,6 +34,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #ifdef CONFIG_SUNRPC_BACKCHANNEL
 struct rpc_rqst *xprt_lookup_bc_request(struct rpc_xprt *xprt, __be32 xid);
 void xprt_complete_bc_request(struct rpc_rqst *req, uint32_t copied);
+void xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task);
 void xprt_free_bc_request(struct rpc_rqst *req);
 int xprt_setup_backchannel(struct rpc_xprt *, unsigned int min_reqs);
 void xprt_destroy_backchannel(struct rpc_xprt *, unsigned int max_reqs);
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 64159716be30..dcefbf406482 100644
--- a/net/sunrpc/clnt.c
+++ b/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;
 }
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 613f558a3791..f5be739492d4 100644
--- a/net/sunrpc/xprt.c
+++ b/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);