selftests: mptcp: make sendfile selftest work

When the selftest got added, sendfile() on mptcp sockets returned
-EOPNOTSUPP, so running 'mptcp_connect.sh -m sendfile' failed
immediately.

This is no longer the case, but the script fails anyway due to timeout.
Let the receiver know once the sender has sent all data, just like
with '-m mmap' mode.

v2: need to respect cfg_wait too, as pm_userspace.sh relied
on -m sendfile to keep the connection open (Mat Martineau)

Fixes: 048d19d4 ("mptcp: add basic kselftest for mptcp")
Reported-by: Xiumei Mu <xmu@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/mptcp/mptcp_connect.c

@@ -553,6 +553,18 @@ static void set_nonblock(int fd, bool nonblock)
 		fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
 }
 
+static void shut_wr(int fd)
+{
+	/* Close our write side, ev. give some time
+	 * for address notification and/or checking
+	 * the current status
+	 */
+	if (cfg_wait)
+		usleep(cfg_wait);
+
+	shutdown(fd, SHUT_WR);
+}
+
 static int copyfd_io_poll(int infd, int peerfd, int outfd, bool *in_closed_after_out)
 {
 	struct pollfd fds = {
@@ -630,14 +642,7 @@ static int copyfd_io_poll(int infd, int peerfd, int outfd, bool *in_closed_after
 					/* ... and peer also closed already */
 					break;
 
-				/* ... but we still receive.
-				 * Close our write side, ev. give some time
-				 * for address notification and/or checking
-				 * the current status
-				 */
-				if (cfg_wait)
-					usleep(cfg_wait);
-				shutdown(peerfd, SHUT_WR);
+				shut_wr(peerfd);
 			} else {
 				if (errno == EINTR)
 					continue;
@@ -767,7 +772,7 @@ static int copyfd_io_mmap(int infd, int peerfd, int outfd,
 		if (err)
 			return err;
 
-		shutdown(peerfd, SHUT_WR);
+		shut_wr(peerfd);
 
 		err = do_recvfile(peerfd, outfd);
 		*in_closed_after_out = true;
@@ -791,6 +796,9 @@ static int copyfd_io_sendfile(int infd, int peerfd, int outfd,
 		err = do_sendfile(infd, peerfd, size);
 		if (err)
 			return err;
+
+		shut_wr(peerfd);
+
 		err = do_recvfile(peerfd, outfd);
 		*in_closed_after_out = true;
 	}