Re: [PATCH 1/2] filemap: Convert generic_perform_write() to support large folios

[Daniel Gomez <da.gomez@samsung.com>]

On Tue, May 28, 2024 at 05:50:44PM +0100, Matthew Wilcox wrote:
> On Tue, May 28, 2024 at 03:23:39PM +0000, Daniel Gomez wrote:
> > I have the same patch for shmem and large folios tree. That was the last piece
> > needed for getting better performance results. However, it is also needed to
> > support folios in the write_begin() and write_end() callbacks.
> 
> I don't think it's *needed*.  It's nice!  But clearly not necessary
> since Christoph made nfs work without doing that.

I see. We send anyway the length with bytes and the folio allocated inside
write_begin() is retrieved with folio_page().

I did test this patch (+mapping_max_folio_size() patch) for shmem an it works fine for me.
> 
> > In order to avoid
> > making them local to shmem, how should we do the transition to folios in these
> > 2 callbacks? I was looking into aops->read_folio approach but what do you think?
> 
> See the v2 of buffer_write_operations that I just posted.  I was waiting
> for feedback from Christoph on the revised method for passing fsdata
> around, but I may as well just post a v2 and see what happens.

Interesting. I think it makes sense to convert tmpfs to
buffered_write_operations as well. Can you add me to the v2 so I can add/review
it for tmpfs?

Thanks