Re: [PATCH 04/13] mm/readahead: add readahead_control->uncached member

[Matthew Wilcox]

On Fri, Nov 08, 2024 at 10:43:27AM -0700, Jens Axboe wrote:
> +++ b/mm/readahead.c
> @@ -191,7 +191,13 @@ static void read_pages(struct readahead_control *rac)
>  static struct folio *ractl_alloc_folio(struct readahead_control *ractl,
>  				       gfp_t gfp_mask, unsigned int order)
>  {
> -	return filemap_alloc_folio(gfp_mask, order);
> +	struct folio *folio;
> +
> +	folio = filemap_alloc_folio(gfp_mask, order);
> +	if (folio && ractl->uncached)
> +		folio_set_uncached(folio);

If we've just allocated it, it should be safe to use
__folio_set_uncached() here, no?

Not that I'm keen on using a folio flag here, but I'm reserving judgement
on that unti I've got further through this series and see how it's used.
I can see that it might be necessary.