Re: [fuse-devel] [PATCH 0/8] MUSE: Userspace backed MTD v3

[Luca Risolia]

Hi guys,

a bit OT probably: is there any chance for you to also implement mmap() 
for CUSE? That would be much appreciated.

Thanks


On 09/02/21 15:35, Richard Weinberger wrote:
> Miklos,
>
> ----- Ursprüngliche Mail -----
> > > The core goal of MUSE is having the complexity on the userspace side and
> > > only a small MTD driver in kernelspace.
> > > While playing with different approaches I realized that FUSE offers everything
> > > we need. So MUSE is a little like CUSE except that it does not implement a
> > > bare character device but an MTD.
> >
> > Looks fine.
>
> I'm glad to hear that!
>
> > I do wonder if MUSE should go to drivers/mtd/ instead.   Long term
> > goal would be move CUSE to drivers/char and move the transport part of
> > fuse into net/fuse leaving only the actual filesystems (fuse and
> > virtiofs) under fs/.
> >
> > But for now just moving the minimal interface needed for MUSE into a
> > separate header (<net/fuse.h>) would work, I guess.
> >
> > Do you think that would make sense?
>
> Yes, I'm all for having MUSE in drivers/mtd/.
>
> I placed MUSE initially in fs/fuse/ because CUSE was already there and muse.c includes
> fuse_i.h. So tried to be as little invasive as possible.
>
> > > Notes:
> > > ------
> > >
> > > - OOB support is currently limited. Currently MUSE has no support for processing
> > >    in- and out-band in the same MTD operation. It is good enough to make JFFS2
> > >    happy. This limitation is because FUSE has no support more than one variable
> > >    length buffer in a FUSE request.
> > >    At least I didn’t find a good way to pass more than one buffer to a request.
> > >    Maybe FUSE folks can correct me. :-)
> >
> > If you look at fuse_do_ioctl() it does variable length input and
> > output at the same time.  I guess you need something similar to that.
>
> I'll dig into this!
>
> Thanks,
> //richard