On Sun, Nov 10, 2024 at 08:28:01AM -0700, Jens Axboe wrote:
> If the folio is marked as uncached, drop pages when writeback completes.
> Intended to be used with RWF_UNCACHED, to avoid needing sync writes for
> uncached IO.
>
> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
> ---
> mm/filemap.c | 23 +++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index bd698340ef24..efd02b047541 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1600,6 +1600,23 @@ int folio_wait_private_2_killable(struct folio *folio)
> }
> EXPORT_SYMBOL(folio_wait_private_2_killable);
>
> +/*
> + * If folio was marked as uncached, then pages should be dropped when writeback
> + * completes. Do that now. If we fail, it's likely because of a big folio -
> + * just reset uncached for that case and latter completions should invalidate.
> + */
> +static void folio_end_uncached(struct folio *folio)
> +{
> + bool reset = true;
> +
> + if (folio_trylock(folio)) {
> + reset = !invalidate_complete_folio2(folio->mapping, folio, 0);
> + folio_unlock(folio);
The same problem with folio_mapped() here.
> + }
> + if (reset)
> + folio_set_uncached(folio);
> +}
> +
> /**
> * folio_end_writeback - End writeback against a folio.
> * @folio: The folio.
--
Kiryl Shutsemau / Kirill A. Shutemov
