do_file_open
file = do_file_open(fd, name, &open_exec_flags);
extern struct file *do_file_open(int dfd, struct filename *pathname,
return do_file_open(AT_FDCWD, name, &op);
return FD_ADD(how->flags, do_file_open(dfd, name, &op));
file = do_file_open(open->dfd, name, &op);