A request cannot be used as part of the RTO estimation if it gets

resent since you don't know whether the server is replying to the
first or the second transmission. However we're currently setting
the cutoff point to be the timeout of the first transmission.

This patch moves the cutoff point to the actual start of the
retransmission.

include/linux/sunrpc/xprt.h

@@ -115,7 +115,7 @@ struct rpc_rqst {
 
 	unsigned long		rq_xtime;	/* when transmitted */
 	int			rq_ntimeo;
-	int			rq_nresend;
+	int			rq_ntrans;
 };
 #define rq_svec			rq_snd_buf.head
 #define rq_slen			rq_snd_buf.len

net/sunrpc/xprt.c

@@ -143,15 +143,17 @@ __xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
 	if (!xprt->snd_task) {
 		if (xprt->nocong || __xprt_get_cong(xprt, task)) {
 			xprt->snd_task = task;
-			if (req)
+			if (req) {
 				req->rq_bytes_sent = 0;
+				req->rq_ntrans++;
+			}
 		}
 	}
 	if (xprt->snd_task != task) {
 		dprintk("RPC: %4d TCP write queue full\n", task->tk_pid);
 		task->tk_timeout = 0;
 		task->tk_status = -EAGAIN;
-		if (req && req->rq_nresend)
+		if (req && req->rq_ntrans)
 			rpc_sleep_on(&xprt->resend, task, NULL, NULL);
 		else
 			rpc_sleep_on(&xprt->sending, task, NULL, NULL);
@@ -189,8 +191,10 @@ __xprt_lock_write_next(struct rpc_xprt *xprt)
 	if (xprt->nocong || __xprt_get_cong(xprt, task)) {
 		struct rpc_rqst *req = task->tk_rqstp;
 		xprt->snd_task = task;
-		if (req)
+		if (req) {
 			req->rq_bytes_sent = 0;
+			req->rq_ntrans++;
+		}
 	}
 }
 
@@ -578,7 +582,7 @@ xprt_complete_rqst(struct rpc_xprt *xprt, struct rpc_rqst *req, int copied)
 	if (!xprt->nocong) {
 		xprt_adjust_cwnd(xprt, copied);
 		__xprt_put_cong(xprt, req);
-	       	if (!req->rq_nresend) {
+	       	if (req->rq_ntrans == 1) {
 			unsigned timer =
 				task->tk_msg.rpc_proc->p_timer;
 			if (timer)
@@ -1064,7 +1068,7 @@ xprt_timer(struct rpc_task *task)
 		goto out;
 
 	xprt_adjust_cwnd(req->rq_xprt, -ETIMEDOUT);
-	req->rq_nresend++;
+	__xprt_put_cong(xprt, req);
 
 	dprintk("RPC: %4d xprt_timer (%s request)\n",
 		task->tk_pid, req ? "pending" : "backlogged");