linux-kernel - Re: [PATCH RFC 24/35] ata: libata-eh: drop nth

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Message-ID: <6bff5a45-8e52-4a5d-81cb-63a7331d7d0b@redhat.com>
Date: Fri, 22 Aug 2025 08:18:40 +0200
From: David Hildenbrand <david@...hat.com>
To: Damien Le Moal <dlemoal@...nel.org>, linux-kernel@...r.kernel.org
Cc: Niklas Cassel <cassel@...nel.org>, Alexander Potapenko
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 Zi Yan <ziy@...dia.com>
Subject: Re: [PATCH RFC 24/35] ata: libata-eh: drop nth_page() usage within SG
 entry

On 22.08.25 03:59, Damien Le Moal wrote:
> On 8/22/25 05:06, David Hildenbrand wrote:
>> It's no longer required to use nth_page() when iterating pages within a
>> single SG entry, so let's drop the nth_page() usage.
>>
>> Cc: Damien Le Moal <dlemoal@...nel.org>
>> Cc: Niklas Cassel <cassel@...nel.org>
>> Signed-off-by: David Hildenbrand <david@...hat.com>
>> ---
>>   drivers/ata/libata-sff.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
>> index 7fc407255eb46..9f5d0f9f6d686 100644
>> --- a/drivers/ata/libata-sff.c
>> +++ b/drivers/ata/libata-sff.c
>> @@ -614,7 +614,7 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
>>   	offset = qc->cursg->offset + qc->cursg_ofs;
>>   
>>   	/* get the current page and offset */
>> -	page = nth_page(page, (offset >> PAGE_SHIFT));
>> +	page += offset / PAGE_SHIFT;
> 
> Shouldn't this be "offset >> PAGE_SHIFT" ?

Thanks for taking a look!

Yeah, I already reverted back to "offset >> PAGE_SHIFT" after Linus 
mentioned in another mail in this thread that ">> PAGE_SHIFT" is 
generally preferred because the compiler cannot optimize as much if 
offset would be a signed variable.

So the next version will have the shift again.

-- 
Cheers

David / dhildenb