linux-kernel - Re: [PATCH v1 35/36] block: update comment of "struct bio_vec" regarding nth

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Message-ID: <c37fc8db-6a3e-48ec-8587-f7f515314b18@lucifer.local>
Date: Thu, 28 Aug 2025 19:19:54 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: David Hildenbrand <david@...hat.com>
Cc: linux-kernel@...r.kernel.org, Alexander Potapenko <glider@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Brendan Jackman <jackmanb@...gle.com>,
        Christoph Lameter <cl@...two.org>, Dennis Zhou <dennis@...nel.org>,
        Dmitry Vyukov <dvyukov@...gle.com>, dri-devel@...ts.freedesktop.org,
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Subject: Re: [PATCH v1 35/36] block: update comment of "struct bio_vec"
 regarding nth_page()

On Thu, Aug 28, 2025 at 12:01:39AM +0200, David Hildenbrand wrote:
> Ever since commit 858c708d9efb ("block: move the bi_size update out of
> __bio_try_merge_page"), page_is_mergeable() no longer exists, and the
> logic in bvec_try_merge_page() is now a simple page pointer
> comparison.
>
> Signed-off-by: David Hildenbrand <david@...hat.com>

Nice! :)

LGTM, so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

> ---
>  include/linux/bvec.h | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/bvec.h b/include/linux/bvec.h
> index 0a80e1f9aa201..3fc0efa0825b1 100644
> --- a/include/linux/bvec.h
> +++ b/include/linux/bvec.h
> @@ -22,11 +22,8 @@ struct page;
>   * @bv_len:    Number of bytes in the address range.
>   * @bv_offset: Start of the address range relative to the start of @bv_page.
>   *
> - * The following holds for a bvec if n * PAGE_SIZE < bv_offset + bv_len:
> - *
> - *   nth_page(@bv_page, n) == @bv_page + n
> - *
> - * This holds because page_is_mergeable() checks the above property.
> + * All pages within a bio_vec starting from @bv_page are contiguous and
> + * can simply be iterated (see bvec_advance()).
>   */
>  struct bio_vec {
>  	struct page	*bv_page;
> --
> 2.50.1
>