Re: [RFC PATCH 10/11] shmem: add large folio support to the write path

[Matthew Wilcox]

On Sat, Oct 28, 2023 at 09:15:50PM +0000, Daniel Gomez wrote:
> +++ b/mm/shmem.c
> @@ -1621,6 +1621,9 @@ static struct folio *shmem_alloc_folio(gfp_t gfp, struct shmem_inode_info *info,
>  	pgoff_t ilx;
>  	struct page *page;
>  
> +	if ((order != 0) && !(gfp & VM_HUGEPAGE))
> +		gfp |= __GFP_COMP;

This is silly.  Just set it unconditionally.

> +static inline unsigned int
> +shmem_mapping_size_order(struct address_space *mapping, pgoff_t index,
> +			 size_t size, struct shmem_sb_info *sbinfo)
> +{
> +	unsigned int order = ilog2(size);
> +
> +	if ((order <= PAGE_SHIFT) ||
> +	    (!mapping_large_folio_support(mapping) || !sbinfo->noswap))
> +		return 0;
> +
> +	order -= PAGE_SHIFT;

You know we have get_order(), right?