Re: [PATCH] fs/writeback: convert wbc_account_cgroup_owner to take a folio

[Matthew Wilcox]

On Thu, Sep 26, 2024 at 04:01:21PM +0200, Pankaj Raghav (Samsung) wrote:
> Convert wbc_account_cgroup_owner() to take a folio instead of a page,
> and convert all callers to pass a folio directly except f2fs.
> 
> Convert the page to folio for all the callers from f2fs as they were the
> only callers calling wbc_account_cgroup_owner() with a page. As f2fs is
> already in the process of converting to folios, these call sites might
> also soon be calling wbc_account_cgroup_owner() with a folio directly in
> the future.

I was hoping for more from f2fs.  I still don't have an answer from them
whether they're going to support large folios.  There's all kinds of
crud already in these functions like:

        f2fs_set_bio_crypt_ctx(bio, fio->page->mapping->host,
                        page_folio(fio->page)->index, fio, GFP_NOIO);

and this patch is making it worse, not better.  A series of patches
which at least started to spread folios throughout f2fs would be better.
I think that struct f2fs_io_info should have its page converted to
a folio, for example.  Although maybe not; perhaps this structure can
carry data which doesn't belong to a folio that came from the page cache.
It's very hard to tell because f2fs is so mind-numbingly complex and
riddled with stupid abstraction layers.

But I don't know what the f2fs maintainers have planned.  And they won't
tell me despite many times of asking.