Re: [PATCH v9 00/17] fuse: fuse-over-io-uring.

[Keith Busch <kbusch@kernel.org>]

On Wed, Jun 18, 2025 at 03:13:41PM +0200, Bernd Schubert wrote:
> On 6/18/25 12:54, xiaobing.li wrote:
> > 
> > Hi Bernd,
> > 
> > Do you have any plans to add zero copy solution? We are interested in
> > FUSE's zero copy solution and conducting research in code.
> > If you have no plans in this regard for the time being, we intend to
> >  submit our solution.
> 
> Hi Xiobing,
> 
> Keith (add to CC) did some work for that in ublk and also planned to
> work on that for fuse (or a colleague). Maybe Keith could
> give an update.

I was initially asked to implement a similar solution that ublk uses for
zero-copy, but the requirements changed such that it won't work. The
ublk server can't directly access the zero-copy buffers. It can only
indirectly refer to it with an io_ring registered buffer index, which is
fine my ublk use case, but the fuse server that I was trying to
enable does in fact need to directly access that data.

My colleauge had been working a solution, but it required shared memory
between the application and the fuse server, and therefore cooperation
between them, which is rather limiting. It's still on his to-do list,
but I don't think it's a high priority at the moment. If you have
something in the works, please feel free to share it when you're ready,
and I would be interested to review.