Re: [PATCH v6 01/26] fuse: Fix dax truncate/punch_hole fault path

Albert Esteve
2025-02-07T16:16:25Z

On Thu, Feb 6, 2025 at 7:22 PM David Hildenbrand <david@redhat.com> wrote:
>
> On 06.02.25 15:59, Albert Esteve wrote:
> > Hi!
> >
> > On Thu, Feb 6, 2025 at 3:30 PM Stefan Hajnoczi <stefanha@redhat.com> wrote:
> >>
> >> On Thu, Feb 06, 2025 at 08:37:07AM -0500, Vivek Goyal wrote:
> >>> And then there are challenges at QEMU level. virtiofsd needs additional
> >>> vhost-user commands to implement DAX and these never went upstream in
> >>> QEMU. I hope these challenges are sorted at some point of time.
> >>
> >> Albert Esteve has been working on QEMU support:
> >> https://lore.kernel.org/qemu-devel/20240912145335.129447-1-aesteve@redhat.com/
> >>
> >> He has a viable solution. I think the remaining issue is how to best
> >> structure the memory regions. The reason for slow progress is not
> >> because it can't be done, it's probably just because this is a
> >> background task.
> >
> > It is partially that, indeed. But what has me blocked for now on posting the
> > next version is that I was reworking a bit the MMAP strategy.
> > Following David comments, I am relying more on RAMBlocks and
> > subregions for mmaps. But this turned out more difficult than anticipated.
>
> Yeah, if that turns out to be too painful, we could start with the
> previous approach and work on that later. I also did not expect that to
> become that complicated.

Thanks. I'd like to do it properly, so I think will try a bit more to get it
to work. Maybe another week. If I do not manage, I may do
what you suggested (I'll align with you first) to move the patch forward.

That said, if I end up doing that, I will definitively revisit it later.

BR,
Albert.

>
> --
> Cheers,
>
> David / dhildenb
>