Re: [PATCH v2 02/15] mm, swap: use unified helper for swap cache look up

[David Hildenbrand]

On 05.09.25 21:13, Kairui Song wrote:
> From: Kairui Song <kasong@xxxxxxxxxxx>
>
> The swap cache lookup helper swap_cache_get_folio currently does
> readahead updates as well, so callers that are not doing swapin from any
> VMA or mapping are forced to reuse filemap helpers instead, and have to
> access the swap cache space directly.
>
> So decouple readahead update with swap cache lookup. Move the readahead
> update part into a standalone helper. Let the caller call the readahead
> update helper if they do readahead. And convert all swap cache lookups
> to use swap_cache_get_folio.
>
> After this commit, there are only three special cases for accessing swap
> cache space now: huge memory splitting, migration, and shmem replacing,
> because they need to lock the XArray. The following commits will wrap
> their accesses to the swap cache too, with special helpers.
>
> And worth noting, currently dropbehind is not supported for anon folio,
> and we will never see a dropbehind folio in swap cache. The unified
> helper can be updated later to handle that.
>
> While at it, add proper kernedoc for touched helpers.
>
> No functional change.
>
> Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>
> Acked-by: Chris Li <chrisl@xxxxxxxxxx>
> Acked-by: Nhat Pham <nphamcs@xxxxxxxxx>
> Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> Reviewed-by: Barry Song <baohua@xxxxxxxxxx>
> ---

Acked-by: David Hildenbrand <david@xxxxxxxxxx>

--
Cheers

David / dhildenb