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@kernel.org>
Cc: Niklas Cassel <cassel@kernel.org>
Signed-off-by: David Hildenbrand <david@redhat.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;
 	offset %= PAGE_SIZE;
 
 	/* don't overrun current sg */
@@ -631,7 +631,7 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
 		unsigned int split_len = PAGE_SIZE - offset;
 
 		ata_pio_xfer(qc, page, offset, split_len);
-		ata_pio_xfer(qc, nth_page(page, 1), 0, count - split_len);
+		ata_pio_xfer(qc, page + 1, 0, count - split_len);
 	} else {
 		ata_pio_xfer(qc, page, offset, count);
 	}
@@ -751,7 +751,7 @@ static int __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
 	offset = sg->offset + qc->cursg_ofs;
 
 	/* get the current page and offset */
-	page = nth_page(page, (offset >> PAGE_SHIFT));
+	page += offset / PAGE_SIZE;
 	offset %= PAGE_SIZE;
 
 	/* don't overrun current sg */
-- 
2.50.1

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@kernel.org>
> Cc: Niklas Cassel <cassel@kernel.org>
> Signed-off-by: David Hildenbrand <david@redhat.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" ?

>  	offset %= PAGE_SIZE;
>  
>  	/* don't overrun current sg */
> @@ -631,7 +631,7 @@ static void ata_pio_sector(struct ata_queued_cmd *qc)
>  		unsigned int split_len = PAGE_SIZE - offset;
>  
>  		ata_pio_xfer(qc, page, offset, split_len);
> -		ata_pio_xfer(qc, nth_page(page, 1), 0, count - split_len);
> +		ata_pio_xfer(qc, page + 1, 0, count - split_len);
>  	} else {
>  		ata_pio_xfer(qc, page, offset, count);
>  	}
> @@ -751,7 +751,7 @@ static int __atapi_pio_bytes(struct ata_queued_cmd *qc, unsigned int bytes)
>  	offset = sg->offset + qc->cursg_ofs;
>  
>  	/* get the current page and offset */
> -	page = nth_page(page, (offset >> PAGE_SHIFT));
> +	page += offset / PAGE_SIZE;

Same here, though this seems correct too.

>  	offset %= PAGE_SIZE;
>  
>  	/* don't overrun current sg */


-- 
Damien Le Moal
Western Digital Research

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@kernel.org>
>> Cc: Niklas Cassel <cassel@kernel.org>
>> Signed-off-by: David Hildenbrand <david@redhat.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