[Pkg-zfsonlinux-devel] Bug#1092598: libzfs6linux ineffectively replaces libzfs4linux (DEP17 P1)

[Helmut Grohne]

Package: libzfs6linux
Version: 2.3.0~rc5-1~exp1
Severity: serious
Justification: file loss in upgrade
User: helmutg at debian.org
Usertags: dep17p1

Hi,

the files
 - /usr/lib/x86_64-linux-gnu/libzfs_core.so.3
 - /usr/lib/x86_64-linux-gnu/libzfs_core.so.3.0.0
are installed by both libzfs6linux and by libzfs4linux. As a result,
libzfs6linux declares Replaces: libzfs4linux. Unfortunately,
libzfs4linux used to install these files below /lib until bookworm. As
such, an upgrade from bookworm to experimental may loose these files.
The issue arises from the /usr-move transition that requested moving
these files from /lib to /usr/lib. For details on the problem category
refer to https://subdivi.de/~helmut/dep17.html section P1.

Until you move libzfs6linux to unstable, this is not a practical
problem, because we consider upgrades from bookworm to experimental
unsupported.

If libzfs6linux is not meant to be part of trixie (but a preparation for
forky), there is no relevant upgrade path as we expect bookworm users to
first upgrade to trixie before upgrading to forky. In that case, please
close this bug report.

Otherwise, libzfs6linux has been added for preparing an update for
trixie. In this case, we must add mitigations. DEP17 suggests multiple
mitigations for this. In order to select a suitable one, I would like to
understand whether this library is potentiall involved in system boot.
In other words whether we risk turning a system unbootable if the
library would go missing. If that is the case, I suggest using a more
elaborate mitigation.

I intend to provide the relevant patches (if any). To provide suitable
patches, I depend on feedback:
 * Is libzfs6linux meant to be included in trixie?
 * If yes, do you see a risk of rendering a system unbootable if
   libzfs_core.so.3 would go missing?

Thanks in advance

Helmut