Re: [LSF/MM/BPF TOPIC] Large folio support: iomap framework changes versus filesystem-specific implementations

[Jaegeuk Kim <jaegeuk@kernel.org>]

On 02/26, Barry Song wrote:
> On Tue, Feb 24, 2026 at 5:36 AM Jaegeuk Kim <jaegeuk@kernel.org> wrote:
> >
> > On 02/20, Matthew Wilcox wrote:
> > > On Fri, Feb 20, 2026 at 07:48:39AM -0800, Christoph Hellwig wrote:
> > > > Maybe you catch on the wrong foot, but this pisses me off.  I've been
> > > > telling you guys to please actually fricking try converting f2fs to
> > > > iomap, and it's been constantly ignored.
> > >
> > > Christoph isn't alone here.  There's a consistent pattern of f2fs going
> > > off and doing weird shit without talking to anyone else.  A good start
> > > would be f2fs maintainers actually coming to LSFMM, but a lot more design
> > > decisions need to be cc'd to linux-fsdevel.
> >
> > What's the benefit of supporting the large folio on the write path? And,
> > which other designs are you talking about?
> >
> > I'm also getting the consistent pattern: 1) posting patches in f2fs for
> > production, 2) requested to post patches modifying the generic layer, 3)
> > posting the converted patches after heavy tests, 4) sitting there for
> > months without progress.
> 
> It can sometimes be a bit tricky for the common layer and
> filesystem-specific layers to coordinate smoothly. At times,
> it can be somewhat frustrating.
> 
> Privately, I know how tough it was for Nanzhe to decide whether
> to make changes in the iomap layer or in filesystem-specific code.
> Nevertheless, he has the dedication and care to implement F2FS
> large folio support in the best possible way, as he has discussed
> with me many times in private.
> 
> I strongly suggest that LSF/MM/BPF invite Kim (and Chao, if possible)
> along with the iomap team to discuss this together—at least
> remotely if not everyone can attend in person.

We don't have a plan to attend this year summit. But I'm open to have an offline
call to discuss about what we can do in f2fs, if you guys are interested in.
Let me know.

> 
> >
> > E.g.,
> > https://lore.kernel.org/lkml/20251202013212.964298-1-jaegeuk@kernel.org/
> 
> Thanks
> Barry