pipe: add ability to restore both ends of inhereted pipes

When we restore an inhereted pipe, we have only one end and we
don't know whether it's write or read one. So we need to call
reopen_pipe each time.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

pipes.c

@@ -314,11 +314,15 @@ static int open_pipe(struct file_desc *d)
 	int pfd[2];
 	int sock;
 
-	if (inherited_fd(d, &tmp))
-		return tmp;
-
 	pi = container_of(d, struct pipe_info, d);
 	pr_info("\t\tCreating pipe pipe_id=%#x id=%#x\n", pi->pe->pipe_id, pi->pe->id);
+	if (inherited_fd(d, &tmp)) {
+		if (tmp < 0)
+			return tmp;
+
+		pi->reopen = 1;
+		goto out;
+	}
 
 	if (!pi->create)
 		return recv_pipe_fd(pi);
@@ -357,6 +361,7 @@ static int open_pipe(struct file_desc *d)
 	close(pfd[!(pi->pe->flags & O_WRONLY)]);
 	tmp = pfd[pi->pe->flags & O_WRONLY];
 
+out:
 	if (pi->reopen)
 		tmp = reopen_pipe(tmp, pi->pe->flags);