[dm-devel] [PATCH 2/4] mm/swap: use SECTORS_PER_PAGE_SHIFT to clean up code

[Leizhen (ThunderTown)]

On 2020/5/6 9:33, Leizhen (ThunderTown) wrote:
> 
> 
> On 2020/5/6 1:25, Matthew Wilcox wrote:
>> On Tue, May 05, 2020 at 07:55:41PM +0800, Zhen Lei wrote:
>>> +++ b/mm/swapfile.c
>>> @@ -177,8 +177,8 @@ static int discard_swap(struct swap_info_struct *si)
>>>  
>>>  	/* Do not discard the swap header page! */
>>>  	se = first_se(si);
>>> -	start_block = (se->start_block + 1) << (PAGE_SHIFT - 9);
>>> -	nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9);
>>> +	start_block = (se->start_block + 1) << SECTORS_PER_PAGE_SHIFT;
>>> +	nr_blocks = ((sector_t)se->nr_pages - 1) << SECTORS_PER_PAGE_SHIFT;
>>
>> Thinking about this some more, wouldn't this look better?
>>
>> 	start_block = page_sectors(se->start_block + 1);
>> 	nr_block = page_sectors(se->nr_pages - 1);
>>
> 
> OK，That's fine, it's clearer. And in this way, there won't be more than 80 columns.

Should we rename "page_sectors" to "page_to_sectors"? Because we may need to define
"sectors_to_page" also.

> 
>>
>> .
>>