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

Richard Weinberger
2021-02-09T14:36:40Z

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