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Date:   Tue, 9 Feb 2021 15:35:57 +0100 (CET)
From:   Richard Weinberger <richard@nod.at>
To:     Miklos Szeredi <miklos@szeredi.hu>
Cc:     Miquel Raynal <miquel.raynal@bootlin.com>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Boris Brezillon <boris.brezillon@collabora.com>,
        Ron Minnich <rminnich@google.com>, sven@narfation.org,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux-mtd <linux-mtd@lists.infradead.org>,
        fuse-devel <fuse-devel@lists.sourceforge.net>
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Subject: Re: [PATCH 0/8] MUSE: Userspace backed MTD v3
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Thread-Topic: MUSE: Userspace backed MTD v3
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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