Re: [RFC PATCH V2 1/9] include/linux/pagemap.h: introduce attach/clear_page_private

[Guoqing Jiang]

On 5/1/20 12:13 AM, Matthew Wilcox wrote:
> On Thu, Apr 30, 2020 at 11:44:42PM +0200, Guoqing Jiang wrote:
> > +/**
> > + * attach_page_private - attach data to page's private field and set PG_private.
> > + * @page: page to be attached and set flag.
> > + * @data: data to attach to page's private field.
> > + *
> > + * Need to take reference as mm.h said "Setting PG_private should also increment
> > + * the refcount".
> > + */
> I don't think this will read well when added to the API documentation.
> Try this:
>
> /**
>   * attach_page_private - Attach private data to a page.
>   * @page: Page to attach data to.
>   * @data: Data to attach to page.
>   *
>   * Attaching private data to a page increments the page's reference count.
>   * The data must be detached before the page will be freed.
>   */
>
> > +/**
> > + * clear_page_private - clear page's private field and PG_private.
> > + * @page: page to be cleared.
> > + *
> > + * The counterpart function of attach_page_private.
> > + * Return: private data of page or NULL if page doesn't have private data.
> > + */
> Seems to me that the opposite of "attach" is "detach", not "clear".
>
> /**
>   * detach_page_private - Detach private data from a page.
>   * @page: Page to detach data from.
>   *
>   * Removes the data that was previously attached to the page and decrements
>   * the refcount on the page.
>   *
>   * Return: Data that was attached to the page.
>   */

Thanks you very much, Mattew! Will change them in next version.

Best Regards,
Guoqing