SUNRPC: Don't receive TCP data into a request buffer that has been reset

If we've removed the request from the receive list, and have added
it back after resetting the request receive buffer, then we should
only receive message data if it is a new reply (i.e. if
transport->recv.copied is zero).

Fixes: 277e4ab ("SUNRPC: Simplify TCP receive code by switching...")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/xprtsock.c

@@ -562,10 +562,14 @@ xs_read_stream_call(struct sock_xprt *transport, struct msghdr *msg, int flags)
 		printk(KERN_WARNING "Callback slot table overflowed\n");
 		return -ESHUTDOWN;
 	}
+	if (transport->recv.copied && !req->rq_private_buf.len)
+		return -ESHUTDOWN;
 
 	ret = xs_read_stream_request(transport, msg, flags, req);
 	if (msg->msg_flags & (MSG_EOR|MSG_TRUNC))
 		xprt_complete_bc_request(req, transport->recv.copied);
+	else
+		req->rq_private_buf.len = transport->recv.copied;
 
 	return ret;
 }
@@ -587,7 +591,7 @@ xs_read_stream_reply(struct sock_xprt *transport, struct msghdr *msg, int flags)
 	/* Look up and lock the request corresponding to the given XID */
 	spin_lock(&xprt->queue_lock);
 	req = xprt_lookup_rqst(xprt, transport->recv.xid);
-	if (!req) {
+	if (!req || (transport->recv.copied && !req->rq_private_buf.len)) {
 		msg->msg_flags |= MSG_TRUNC;
 		goto out;
 	}
@@ -599,6 +603,8 @@ xs_read_stream_reply(struct sock_xprt *transport, struct msghdr *msg, int flags)
 	spin_lock(&xprt->queue_lock);
 	if (msg->msg_flags & (MSG_EOR|MSG_TRUNC))
 		xprt_complete_rqst(req->rq_task, transport->recv.copied);
+	else
+		req->rq_private_buf.len = transport->recv.copied;
 	xprt_unpin_rqst(req);
 out:
 	spin_unlock(&xprt->queue_lock);