linux-kernel - Re: [PATCH] readahead: Use folio_nr_pages() instead of shift operation

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Message-ID: <661ccfa4-a5ad-4370-a7f5-e17968d8a46e@163.com>
Date: Sat, 12 Jul 2025 10:23:32 +0800
From: Chi Zhiling <chizhiling@....com>
To: David Hildenbrand <david@...hat.com>, willy@...radead.org,
 akpm@...ux-foundation.org
Cc: linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, Chi Zhiling <chizhiling@...inos.cn>,
 Ryan Roberts <ryan.roberts@....com>
Subject: Re: [PATCH] readahead: Use folio_nr_pages() instead of shift
 operation

On 2025/7/12 00:15, David Hildenbrand wrote:
> On 10.07.25 08:04, Chi Zhiling wrote:
>> From: Chi Zhiling <chizhiling@...inos.cn>
>>
>> folio_nr_pages() is faster helper function to get the number of pages
>> when NR_PAGES_IN_LARGE_FOLIO is enabled.
>>
>> Signed-off-by: Chi Zhiling <chizhiling@...inos.cn>
>> ---
>>   mm/readahead.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/readahead.c b/mm/readahead.c
>> index 95a24f12d1e7..406756d34309 100644
>> --- a/mm/readahead.c
>> +++ b/mm/readahead.c
>> @@ -649,7 +649,7 @@ void page_cache_async_ra(struct readahead_control 
>> *ractl,
>>        * Ramp up sizes, and push forward the readahead window.
>>        */
>>       expected = round_down(ra->start + ra->size - ra->async_size,
>> -            1UL << folio_order(folio));
>> +            folio_nr_pages(folio));
>>       if (index == expected) {
>>           ra->start += ra->size;
>>           /*
> 
> This should probably get squashed in Ryans commit?

I have no objection, it's up to Ryan.

> 
> LGTM

Thanks,

>