Re: [PATCH v4 25/25] docs: fuse: add io-uring bufring and zero-copy documentation

[Joanne Koong <joannelkoong@gmail.com>]

On Tue, Feb 3, 2026 at 10:56 AM Bernd Schubert <bernd@bsbernd.com> wrote:
>
>
>
> On 1/17/26 00:30, Joanne Koong wrote:
> > Add documentation for fuse over io-uring usage of kernel-managed
> > bufrings and zero-copy.
> >
> > Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
> > ---
> >  .../filesystems/fuse/fuse-io-uring.rst        | 59 ++++++++++++++++++-
> >  1 file changed, 58 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/filesystems/fuse/fuse-io-uring.rst b/Documentation/filesystems/fuse/fuse-io-uring.rst
> > index d73dd0dbd238..11c244b63d25 100644
> > --- a/Documentation/filesystems/fuse/fuse-io-uring.rst
> > +++ b/Documentation/filesystems/fuse/fuse-io-uring.rst
> > @@ -95,5 +95,62 @@ Sending requests with CQEs
> >   |    <fuse_unlink()                         |
> >   |  <sys_unlink()                            |
> >
> > +Kernel-managed buffer rings
> > +===========================
> >
> > -
> > +Kernel-managed buffer rings have two main advantages:
> > +
> > +* eliminates the overhead of pinning/unpinning user pages and translating
> > +  virtual addresses for every server-kernel interaction
> > +* reduces buffer memory allocation requirements
> > +
> > +In order to use buffer rings, the server must preregister the following:
> > +
> > +* a fixed buffer at index 0. This is where the headers will reside
> > +* a kernel-managed buffer ring. This is where the payload will reside
>
> Would you mind to add the actual liburing call for this? I think it
> would be helpful for anyone who wants to implement it.

Good idea, I think what might be even more helpful is to refer them to
the libfuse lib/lowlevel_fuse.c file for reference on how to set this
up. Then they could just copy/paste the code directly from libfuse if
they're trying to do something similar. I'll add this in for the next
version.

Thanks,
Joanne

>
> > +
> > +At a high-level, this is how fuse uses buffer rings: