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

[Jaegeuk Kim <jaegeuk@kernel.org>]

On 02/27, Barry Song wrote:
> On Fri, Feb 27, 2026 at 10:02 AM Jaegeuk Kim <jaegeuk@kernel.org> wrote:
> >
> > 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
> 
> It’s truly a shame, but I understand that you have prior commitments.
> 
> > call to discuss about what we can do in f2fs, if you guys are interested in.
> > Let me know.
> 
> Many thanks for your willingness to have an offline call.
> 
> Absolutely, I’m very interested. I spoke with Nanzhe today, and he’ll
> prepare documents and code to review with you, gather your feedback,
> and incorporate all your guidance.

Thanks. Let's talk in a separate thread.

> 
> Nanzhe can then bring all the points to LSF afterward
> if the topic is scheduled.
> 
> > > >
> > > > E.g.,
> > > > https://lore.kernel.org/lkml/20251202013212.964298-1-jaegeuk@kernel.org/
> > >
> 
> Thanks
> Barry