linux-kernel - Re: [PATCH 0/2] Prevent re-use of FUSE superblock after force unmount

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Date:   Wed, 11 May 2022 21:19:16 +1000
From:   Daniil Lunev <dlunev@...omium.org>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     linux-fsdevel@...r.kernel.org,
        fuse-devel <fuse-devel@...ts.sourceforge.net>,
        linux-kernel@...r.kernel.org,
        Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH 0/2] Prevent re-use of FUSE superblock after force unmount

> At a glance it's a gross hack.   I can think of more than one way in
> which this could be achieved without adding a new field to struct
> super_block.
Can you advise what would be a better way to achieve that?

> But...  what I'd really prefer is if the underlying issue of fuse vs.
> suspend was properly addressed instead of adding band-aids.  And that
> takes lots more resources, for sure, and the result is not guaranteed.
> But you could at least give it a try.
We do have a limited success with userspace level sequencing of processes,
but on the kernel level - it is all quite untrivial, as you mentioned.
I did some
research, and what I found pretty much a 9 years old thread which went
nowhere at the end [1]. We would also prefer if suspend just worked (and
we have a person looking into what is actually breaking with suspend), but
there is an unbounded amount of time for how long the investigation and
search for a solution may be ongoing given the complexity of the problem,
and in the meantime there is no way to work around the problem.

Thanks,
Daniil

[1] https://linux-kernel.vger.kernel.narkive.com/UeBWfN1V/patch-fuse-make-fuse-daemon-frozen-along-with-kernel-threads