GNU bug report logs - #53407
libfuse 3 can't find fusermount

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Leo Famulari <leo <at> famulari.name>
To: bug-guix <at> gnu.org
Subject: libfuse 3 can't find fusermount
Date: Fri, 21 Jan 2022 02:41:49 -0500

[Message part 1 (text/plain, inline)]

While testing a Borg update (patch attached), I noticed that the
FUSERMOUNT_DIR hack in Fuse 3 doesn't seem to work like it does with
Fuse 2.

The 1.2.0b3 beta of the upcoming Borg release can use either Fuse 2
(with python-llfuse) or Fuse 3 (with python-pyfuse3).

The `borg mount` command works as expected with Fuse 2 / llfuse.

But, with Fuse 3 / pyfuse3, it fails with:

fuse: failed to exec fusermount3: No such file or directory

When I commented out the FUSERMOUNT_DIR [0] substitution in the fuse-3
package and rebuilt Borg, `borg mount` instead gives us this, which is
expected, because this system does not have a setuid fusermount3:

fusermount3: mount failed: Operation not permitted

So, the substitution doesn't seem to help with Fuse 3: it just breaks
the lookup.

You can apply the patch and test it out. And you can also observe the
optimal behaviour if you switch the borg package's fuse implementation
from pyfuse3 to llfuse / Fuse 2.

Should we just remove the substitution in fuse-3?

[0]
https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/packages/linux.scm?id=b09f2aa4dae7e2a2f0f37ba831a2428fee8557d2#n3306

[fusermount-borg.diff (text/plain, attachment)]

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Message #8 received at 53407 <at> debbugs.gnu.org (full text, mbox):

From: Liliana Marie Prikler <liliana.prikler <at> ist.tugraz.at>
To: Leo Famulari <leo <at> famulari.name>, 53407 <at> debbugs.gnu.org
Subject: Re: libfuse 3 can't find fusermount
Date: Fri, 21 Jan 2022 08:55:23 +0100

Hi Leo,

Am Freitag, dem 21.01.2022 um 02:41 -0500 schrieb Leo Famulari:
> While testing a Borg update (patch attached), I noticed that the
> FUSERMOUNT_DIR hack in Fuse 3 doesn't seem to work like it does with
> Fuse 2.
> 
> The 1.2.0b3 beta of the upcoming Borg release can use either Fuse 2
> (with python-llfuse) or Fuse 3 (with python-pyfuse3).
> 
> The `borg mount` command works as expected with Fuse 2 / llfuse.
> 
> But, with Fuse 3 / pyfuse3, it fails with:
> 
> fuse: failed to exec fusermount3: No such file or directory
> 
> When I commented out the FUSERMOUNT_DIR [0] substitution in the fuse-
> 3 package and rebuilt Borg, `borg mount` instead gives us this, which
> is expected, because this system does not have a setuid fusermount3:
> 
> fusermount3: mount failed: Operation not permitted
> 
> So, the substitution doesn't seem to help with Fuse 3: it just breaks
> the lookup.
> 
> You can apply the patch and test it out. And you can also observe the
> optimal behaviour if you switch the borg package's fuse
> implementation from pyfuse3 to llfuse / Fuse 2.
> 
> Should we just remove the substitution in fuse-3?
What is the behaviour if you have fusermount3 setuid?  I know from gvfs
(which also depends on Fuse 3), that adding the setuid binary *does*
make gvfsd-fuse work again, so it'd be good to know if this works for
borg as well.  If not, we'd have to be careful not to introduce a
regression. 


Cheers

Message #11 received at 53407 <at> debbugs.gnu.org (full text, mbox):

From: Leo Famulari <leo <at> famulari.name>
To: Liliana Marie Prikler <liliana.prikler <at> ist.tugraz.at>
Cc: 53407 <at> debbugs.gnu.org
Subject: Re: libfuse 3 can't find fusermount
Date: Fri, 21 Jan 2022 12:17:23 -0500

On Fri, Jan 21, 2022 at 08:55:23AM +0100, Liliana Marie Prikler wrote:
> What is the behaviour if you have fusermount3 setuid?

Then, it does work.

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