Re: [PATCH RFC 24/35] ata: libata-eh: drop nth_page() usage within SG entry

Damien Le Moal
2025-08-22T02:02:13Z

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