Re: [PATCH RFC v2 00/19] fuse: fuse-over-io-uring

[Josef Bacik <josef@toxicpanda.com>]

On Thu, May 30, 2024 at 06:17:29PM +0200, Bernd Schubert wrote:
> 
> 
> On 5/30/24 18:10, Kent Overstreet wrote:
> > On Thu, May 30, 2024 at 06:02:21PM +0200, Bernd Schubert wrote:
> >> Hmm, initially I had thought about writing my own ring buffer, but then 
> >> io-uring got IORING_OP_URING_CMD, which seems to have exactly what we
> >> need? From interface point of view, io-uring seems easy to use here, 
> >> has everything we need and kind of the same thing is used for ublk - 
> >> what speaks against io-uring? And what other suggestion do you have?
> >>
> >> I guess the same concern would also apply to ublk_drv. 
> >>
> >> Well, decoupling from io-uring might help to get for zero-copy, as there
> >> doesn't seem to be an agreement with Mings approaches (sorry I'm only
> >> silently following for now).
> >>
> >> From our side, a customer has pointed out security concerns for io-uring. 
> >> My thinking so far was to implemented the required io-uring pieces into 
> >> an module and access it with ioctls... Which would also allow to
> >> backport it to RHEL8/RHEL9.
> > 
> > Well, I've been starting to sketch out a ringbuffer() syscall, which
> > would work on any (supported) file descriptor and give you a ringbuffer
> > for reading or writing (or call it twice for both).
> > 
> > That seems to be what fuse really wants, no? You're already using a file
> > descriptor and your own RPC format, you just want a faster
> > communications channel.
> 
> Fine with me, if you have something better/simpler with less security
> concerns - why not. We just need a community agreement on that.
> 
> Do you have something I could look at?

FWIW I have no strong feelings between using iouring vs any other ringbuffer
mechanism we come up with in the future.

That being said iouring is here now, is proven to work, and these are good
performance improvements.  If in the future something else comes along that
gives us better performance then absolutely we should explore adding that
functionality.  But this solves the problem today, and I need the problem solved
yesterday, so continuing with this patchset is very much a worthwhile
investment, one that I'm very happy you're tackling Bernd instead of me ;).
Thanks,

Josef