Bug#1050333: bullseye-pu: package ltsp/21.01-1+deb11u1

[Mike Gabriel]

Package: release.debian.org
Severity: normal
Tags: bullseye
User: release.d...@packages.debian.org
Usertags: pu
X-Debbugs-Cc: lt...@packages.debian.org, alk...@gmail.com, vag...@debian.org
Control: affects -1 + src:ltsp

Similar to the bookworm-pu #1050090 for ltsp, the same fix needs to land
in Debian bullseye. However, we gained more knowledge about it (see under
IMPORTANT below).

While preparing the initial Debian Edu 12 release, we came across a problem in
LTSP. Thin client machines and diskless workstations started failing to boot
from NFS-located chroot environments.

[ Reason ]
The underlying cause is a regression in the linux kernel since version 5.15
(see #1049885 [1]) for details.

A workaround could be found for LTSP in Debian 12 (it is not just a
Debian Edu problem). This upload provides this workaround and brings
back above named functionality (PXE-booting Debian systems via LTSP
when the system is a chroot tree on NFS).

IMPORTANT: Why provide this fix for bullseye then? The design in recent LTSP
is that the LTSP host creates a kind of ltsp-initrd containing the LTSP
software. This ltsp-initrd gets created by the host and is then used for
whatever target OS shall be booted. The kernel comes from the target OS, but
the ltsp-initrd comes from the LTSP host.

If one want to boot into a bookworm LTSP system (e.g. via PXE) and this bookworm
system gets served by a bullseye LTSP host, then the startup failed as described
in [1] occurs. So, the ltsp-initrd needs the proposed patch which needs to be
shipped in the Debian version of the LTSP host, thus (in this example) Debian
bullseye.

[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1049885

[ Impact ]
LTSP clients with a rootfs containing a kernel newer than 5.15 can't be booted
with LTSP (from a bullseye LTSP host) if rootfs is on NFS.

[ Tests ]
Manual tests on a Debian Edu 11 network.

[ Risks ]
Another regression might have been introduced into LTSP with that workaround.

[ Checklist ]
[x] *all* changes are documented in the d/changelog
[x] I reviewed all changes and I approve them
[x] attach debdiff against the package in (old)stable
[x] the issue is verified as fixed in unstable

[ Changes ]

+ * debian/patches:
+ + Add 0001_Avoid-mv-on-init-symlink-in-order-to-work-around-ove.patch
+ (cherry-picked from upstream). Avoid mv on init symlink in order to
+ work around overlayfs issue. (Closes: #1049397).

[ Other info ]
This issue has been discussed with and approved by LTSP upstream.

See: https://github.com/ltsp/ltsp/issues/860#issuecomment-1682047744

[Adam D Barratt]

package release.debian.org
tags 1050333 = bullseye pending
thanks

Hi,

The upload referenced by this bug report has been flagged for acceptance into the proposed-updates queue for Debian bullseye.

Thanks for your contribution!

Upload details
==============

Package: ltsp
Version: 21.01-1+deb11u1

Explanation: avoid using "mv" on init symlink in order to work around overlayfs issue