Re: [RFC PATCH 1/9] include/linux/pagemap.h: introduce set/clear_fs_page_private

[Christoph Hellwig]

Why not attach_page_private and clear_page_private as that conveys
the use case a little better?

> +static inline void *set_fs_page_private(struct page *page, void *data)
> +{
> +	get_page(page);
> +	set_page_private(page, (unsigned long)data);
> +	SetPagePrivate(page);
> +
> +	return data;
> +}
> +
> +static inline void *clear_fs_page_private(struct page *page)
> +{
> +	void *data = (void *)page_private(page);
> +
> +	if (!PagePrivate(page))
> +		return NULL;
> +	ClearPagePrivate(page);
> +	set_page_private(page, 0);
> +	put_page(page);
> +
> +	return data;
> +}

Can you add kerneldoc comments describing them, including why we
take the refernces?  Also what is the point of the return value
of set_fs_page_private?