Re: bio_vec, bv_page and folios

[Matthew Wilcox]

On Tue, Jan 02, 2024 at 10:03:58AM +0000, David Howells wrote:
> Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
> 
> > On Tue, Jan 02, 2024 at 08:56:46AM +0000, David Howells wrote:
> > > Hi Christoph, Willy,
> > > 
> > > Will bv_page in struct bio_vec ever become a folio pointer rather than I page
> > > pointer?  I'm guessing not as it still presumably needs to be able to point to
> > > non-folio pages.
> > 
> > My plan for bio_vec is that it becomes phyr -- a physical address +
> > length.  No more page or folio reference.
> 
> Interesting...  What does that mean for those places that currently use
> bv_page as a place to stash a pointer to the page and use it to clean up the
> page later?

I don't intend to get rid of bio_for_each_folio_all() or bio_add_page()
for example.  It's just a phys_to_page() away.  The advantage is that
we wouldn't need a struct page to do I/O to a physical address.