Re: [PATCH v15 01/17] block: Add bio_add_folio()

Matthew Wilcox
2021-07-20T11:17:42Z

On Tue, Jul 20, 2021 at 07:42:00AM +0100, Christoph Hellwig wrote:
> On Mon, Jul 19, 2021 at 07:39:45PM +0100, Matthew Wilcox (Oracle) wrote:
> > +/**
> > + * bio_add_folio - Attempt to add part of a folio to a bio.
> > + * @bio: Bio to add to.
> > + * @folio: Folio to add.
> > + * @len: How many bytes from the folio to add.
> > + * @off: First byte in this folio to add.
> > + *
> > + * Always uses the head page of the folio in the bio. If a submitter only
> > + * uses bio_add_folio(), it can count on never seeing tail pages in the
> > + * completion routine. BIOs do not support folios that are 4GiB or larger.
> > + *
> > + * Return: The number of bytes from this folio added to the bio.
> > + */
> > +size_t bio_add_folio(struct bio *bio, struct folio *folio, size_t len,
> > + size_t off)
> > +{
> > + if (len > UINT_MAX || off > UINT_MAX)
> > + return 0;
> > + return bio_add_page(bio, &folio->page, len, off);
> > +}
>
> I'd use the opportunity to switch to a true/false return instead of
> the length. This has been on my todo list for bio_add_page for a while,
> so it might make sense to start out the new API the right way.

ok.