Re: [PATCH 03/17] mm: Add folio_pincount_ptr()

[William Kucharski <william.kucharski@oracle.com>]

Comment inline.

> On Jan 2, 2022, at 2:57 PM, Matthew Wilcox (Oracle) <willy@infradead.org> wrote:
> 
> This is the folio equivalent of compound_pincount_ptr().
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
> include/linux/mm_types.h | 6 ++++++
> 1 file changed, 6 insertions(+)
> 
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index c3a6e6209600..09d9e2c4a2c5 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -309,6 +309,12 @@ static inline atomic_t *compound_mapcount_ptr(struct page *page)
> 	return &page[1].compound_mapcount;
> }
> 
> +static inline atomic_t *folio_pincount_ptr(struct folio *folio)
> +{
> +	struct page *tail = &folio->page + 2;

Please add a comment explaining why this is "2."

> +	return &tail->hpage_pinned_refcount;
> +}
> +
> static inline atomic_t *compound_pincount_ptr(struct page *page)
> {
> 	return &page[2].hpage_pinned_refcount;
> -- 
> 2.33.0
>