losetup: cannot find an unused loop device

[psamim]

losetup: cannot find an unused loop device

[psamim]

I am not sure if it helps, the old working version is tomb-git-2.9.r21.g9323c1c-1-any.pkg.tar.zst the new version is tomb-git-2.9.r25.g6955719-1-any.pkg.tar.zst.

[Narrat]

Thanks for the report and the hints when it worked an when it stopped.
git bisect gives this result:

03c93ef976c6555dec2f0b07dc8c8e37d2c5f766 is the first bad commit
commit 03c93ef976c6555dec2f0b07dc8c8e37d2c5f766
Author: Jaromil <[email protected]>
Date:   Sun Feb 20 21:57:05 2022 +0100

    Sudo loopback improve (#435)

Will take a look at 03c93ef

[Narrat]

As far as I could deduce, loseetup -f needs evelated privileges if it needs to create the next ununsed loop device.
Example: If there is no /dev/loop0. losetup -f needs privileges to return the newly created dev/loop0. If it does exist and the device is unused, losetup -f doesn't need root rights to return the same. Is /dev/loop0 in use, losetup -f needs root rights again to return /dev/loop1.
tl;dr: https://github.com/dyne/Tomb/blob/master/tomb#L633 needs _sudo, which got removed in the commit mentioned by git bisect

[Narrat]

By chance I found this documentation from the kernel regarding loop devices and the changed/different behaviour:
BLK_DEV_LOOP_MIN

The historic default is 8. If a late 2011 version of losetup(8)
is used, it can be set to 0, since needed loop devices can be
dynamically allocated with the /dev/loop-control interface.

So it depends on the used kernel config if the check works without privilege escalation (or not)