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

["David Hildenbrand (Arm)" <david@kernel.org>]

On 3/30/26 12:10, Li Wang wrote:
>>> 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)

I would suggest that you query the alignment only once, and forward it
to the test.

-- 
Cheers,

David