Re: [PATCH v3] selftests/mm: skip hugetlb_dio tests when DIO alignment is incompatible

[Li Wang <liwang@redhat.com>]

> > Why can't we simply open the file once and pass the fd to run_dio_using_hugetlb()?
> > 
> > fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT, 0664);
> > if (fd < 0)
> > 	ksft_exit_skip("Unable to allocate file: %s\n", strerror(errno));
> > dio_align = get_dio_alignment(fd);
> > if (dio_align <= 0)
> > 	ksft_exit_skip("Unable to obtain DIO alignment: %s\n", strerror(errno));
> 
> Yes, apparently this is a good suggestion. Thanks!

And, to make the test elegant, I'm going to add check_dio_alignment() dedicated
to alignment checking. Then we don't need to pass too many args.

Tell me your thoughts if you don't like this:

  static int get_dio_alignment(int fd)
  {...}
  
  static bool check_dio_alignment(unsigned int start_off, unsigned int end_off)
  {...}
  
  static void run_test(int fd, unsigned int start_off, unsigned int end_off)
  {
      if (!check_dio_alignment(start_off, end_off))
          return;
  
      run_dio_using_hugetlb(fd, start_off, end_off);
  }
  
  int main(void)
  {
      ... 
      fd = open("/tmp", O_TMPFILE | O_RDWR | O_DIRECT, 0664);
      if (fd < 0)
          ksft_exit_skip("Unable to allocate file: %s\n", strerror(errno));
  
      if (get_dio_alignment(fd) < 0)
          ...
  
      run_test(fd, 0, (pagesize * 3));
  }

-- 
Regards,
Li Wang