SUNRPC: Don't reuse bvec on retransmission of the request

If a request is re-encoded and then retransmitted, we need to make sure
that we also re-encode the bvec, in case the page lists have changed.

Fixes: ff053db ("SUNRPC: Move the call to xprt_send_pagedata() out of xprt_sock_sendmsg()")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Author: Trond Myklebust

include/linux/sunrpc/xprt.h

@@ -144,7 +144,8 @@ struct rpc_xprt_ops {
 	unsigned short	(*get_srcport)(struct rpc_xprt *xprt);
 	int		(*buf_alloc)(struct rpc_task *task);
 	void		(*buf_free)(struct rpc_task *task);
-	int		(*prepare_request)(struct rpc_rqst *req);
+	int		(*prepare_request)(struct rpc_rqst *req,
+					   struct xdr_buf *buf);
 	int		(*send_request)(struct rpc_rqst *req);
 	void		(*wait_for_reply_request)(struct rpc_task *task);
 	void		(*timer)(struct rpc_xprt *xprt, struct rpc_task *task);

net/sunrpc/clnt.c

@@ -1870,7 +1870,6 @@ rpc_xdr_encode(struct rpc_task *task)
 	req->rq_snd_buf.head[0].iov_len = 0;
 	xdr_init_encode(&xdr, &req->rq_snd_buf,
 			req->rq_snd_buf.head[0].iov_base, req);
-	xdr_free_bvec(&req->rq_snd_buf);
 	if (rpc_encode_header(task, &xdr))
 		return;
 

net/sunrpc/xprt.c

@@ -73,7 +73,7 @@ static void	xprt_init(struct rpc_xprt *xprt, struct net *net);
 static __be32	xprt_alloc_xid(struct rpc_xprt *xprt);
 static void	xprt_destroy(struct rpc_xprt *xprt);
 static void	xprt_request_init(struct rpc_task *task);
-static int	xprt_request_prepare(struct rpc_rqst *req);
+static int	xprt_request_prepare(struct rpc_rqst *req, struct xdr_buf *buf);
 
 static DEFINE_SPINLOCK(xprt_list_lock);
 static LIST_HEAD(xprt_list);
@@ -1149,7 +1149,7 @@ xprt_request_enqueue_receive(struct rpc_task *task)
 	if (!xprt_request_need_enqueue_receive(task, req))
 		return 0;
 
-	ret = xprt_request_prepare(task->tk_rqstp);
+	ret = xprt_request_prepare(task->tk_rqstp, &req->rq_rcv_buf);
 	if (ret)
 		return ret;
 	spin_lock(&xprt->queue_lock);
@@ -1179,8 +1179,11 @@ xprt_request_dequeue_receive_locked(struct rpc_task *task)
 {
 	struct rpc_rqst *req = task->tk_rqstp;
 
-	if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
+	if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
 		xprt_request_rb_remove(req->rq_xprt, req);
+		xdr_free_bvec(&req->rq_rcv_buf);
+		req->rq_private_buf.bvec = NULL;
+	}
 }
 
 /**
@@ -1336,8 +1339,14 @@ xprt_request_enqueue_transmit(struct rpc_task *task)
 {
 	struct rpc_rqst *pos, *req = task->tk_rqstp;
 	struct rpc_xprt *xprt = req->rq_xprt;
+	int ret;
 
 	if (xprt_request_need_enqueue_transmit(task, req)) {
+		ret = xprt_request_prepare(task->tk_rqstp, &req->rq_snd_buf);
+		if (ret) {
+			task->tk_status = ret;
+			return;
+		}
 		req->rq_bytes_sent = 0;
 		spin_lock(&xprt->queue_lock);
 		/*
@@ -1397,6 +1406,7 @@ xprt_request_dequeue_transmit_locked(struct rpc_task *task)
 	} else
 		list_del(&req->rq_xmit2);
 	atomic_long_dec(&req->rq_xprt->xmit_queuelen);
+	xdr_free_bvec(&req->rq_snd_buf);
 }
 
 /**
@@ -1433,34 +1443,35 @@ xprt_request_dequeue_xprt(struct rpc_task *task)
 	    test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
 	    xprt_is_pinned_rqst(req)) {
 		spin_lock(&xprt->queue_lock);
-		xprt_request_dequeue_transmit_locked(task);
-		xprt_request_dequeue_receive_locked(task);
 		while (xprt_is_pinned_rqst(req)) {
 			set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
 			spin_unlock(&xprt->queue_lock);
 			xprt_wait_on_pinned_rqst(req);
 			spin_lock(&xprt->queue_lock);
 			clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
 		}
+		xprt_request_dequeue_transmit_locked(task);
+		xprt_request_dequeue_receive_locked(task);
 		spin_unlock(&xprt->queue_lock);
 	}
 }
 
 /**
  * xprt_request_prepare - prepare an encoded request for transport
  * @req: pointer to rpc_rqst
+ * @buf: pointer to send/rcv xdr_buf
  *
  * Calls into the transport layer to do whatever is needed to prepare
  * the request for transmission or receive.
  * Returns error, or zero.
  */
 static int
-xprt_request_prepare(struct rpc_rqst *req)
+xprt_request_prepare(struct rpc_rqst *req, struct xdr_buf *buf)
 {
 	struct rpc_xprt *xprt = req->rq_xprt;
 
 	if (xprt->ops->prepare_request)
-		return xprt->ops->prepare_request(req);
+		return xprt->ops->prepare_request(req, buf);
 	return 0;
 }
 
@@ -1961,8 +1972,6 @@ void xprt_release(struct rpc_task *task)
 	spin_unlock(&xprt->transport_lock);
 	if (req->rq_buffer)
 		xprt->ops->buf_free(task);
-	xdr_free_bvec(&req->rq_rcv_buf);
-	xdr_free_bvec(&req->rq_snd_buf);
 	if (req->rq_cred != NULL)
 		put_rpccred(req->rq_cred);
 	if (req->rq_release_snd_buf)

net/sunrpc/xprtsock.c

@@ -822,17 +822,9 @@ static int xs_stream_nospace(struct rpc_rqst *req, bool vm_wait)
 	return ret;
 }
 
-static int
-xs_stream_prepare_request(struct rpc_rqst *req)
+static int xs_stream_prepare_request(struct rpc_rqst *req, struct xdr_buf *buf)
 {
-	gfp_t gfp = rpc_task_gfp_mask();
-	int ret;
-
-	ret = xdr_alloc_bvec(&req->rq_snd_buf, gfp);
-	if (ret < 0)
-		return ret;
-	xdr_free_bvec(&req->rq_rcv_buf);
-	return xdr_alloc_bvec(&req->rq_rcv_buf, gfp);
+	return xdr_alloc_bvec(buf, rpc_task_gfp_mask());
 }
 
 /*