zdtm: open an one unlinked files two times

A few test check restoring of file descriptors to a one file struct.
Here is better to check, that a few file struct can be linked to one unlinked file.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm/live/static/write_read10.c

@@ -18,7 +18,7 @@ TEST_OPTION(filename, string, "file name", 1);
 
 int main(int argc, char ** argv)
 {
-	int fd, ret;
+	int fd, child_fd, ret;
 	pid_t pid;
 	uint32_t crc;
 	uint8_t buf[1000000];
@@ -31,6 +31,12 @@ int main(int argc, char ** argv)
 		exit(1);
 	}
 
+	child_fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0644);
+	if (fd < 0) {
+		err("can't open %s: %m\n", filename);
+		exit(1);
+	}
+
 	if (unlink(filename)) {
 		err("can't unlink %s: %m\n", filename);
 		exit(1);
@@ -43,17 +49,20 @@ int main(int argc, char ** argv)
 	}
 
 	if (pid == 0) {	/* child writes to the unlinked file and returns */
+		close(fd);
 		test_waitsig();
 
 		crc = ~0;
 		datagen(buf, sizeof(buf), &crc);
-		if (write(fd, buf, sizeof(buf)) != sizeof(buf))
+		if (write(child_fd, buf, sizeof(buf)) != sizeof(buf))
 			_exit(errno);
 
-		close(fd);
+		close(child_fd);
 		_exit(0);
 	}
 
+	close(child_fd);
+
 	test_daemon();
 	test_waitsig();