Force the call of systemd-journal-flush before `/var` unmount

The problem with failed `/var` unmount placed on separate partition
have a long story: https://github.com/systemd/systemd/issues/867
According messages after the fix integrated into upstream -- there are
some corner cases which aren't fully fixed by patches adding [relinquish
options](pkg/systemd!26

)

In case of ostree-based images we have a similar issue since `/var` is
bind-mounted in initramfs. Systemd is trying to unmount `/var` on
shutdown, however `ExecStop=` command from `systemd-journal-flush`
service is not executed during shutdown.
By adding `PartOf=var.mount` into service file we force the
`systemd-journal-flush.service` to be called prior the `/var` unmount.
This allow to unlock the bind-mount, since `journald` have a chance to
re-link it's journal into `/run` with `journalctl
--smart-relinquish-var` call.

Signed-off-by: Denis Pynkin <denis.pynkin@collabora.com>

debian/patches/apertis/Force-the-call-of-systemd-journal-flush-before-var-u.patch

+From f09e75bfb76f747e966b5ee9c5843a66177871dd Mon Sep 17 00:00:00 2001
+From: Denis Pynkin <denis.pynkin@collabora.com>
+Date: Tue, 17 Nov 2020 20:03:17 +0300
+Subject: [PATCH] Force the call of systemd-journal-flush before `/var` unmount
+
+The problem with failed `/var` unmount placed on separate partition
+have a long story: https://github.com/systemd/systemd/issues/867
+According messages after the fix integrated into upstream -- there are
+some corner cases which aren't fully fixed by patches adding [relinquish
+options](https://gitlab.apertis.org/pkg/systemd/-/merge_requests/26)
+
+In case of ostree-based images we have a similar issue since `/var` is
+bind-mounted in initramfs. Systemd is trying to unmount `/var` on
+shutdown, however `ExecStop=` command from `systemd-journal-flush`
+service is not executed during shutdown.
+By adding `PartOf=var.mount` into service file we force the
+`systemd-journal-flush.service` to be called prior the `/var` unmount.
+This allow to unlock the bind-mount, since `journald` have a chance to
+re-link it's journal into `/run` with `journalctl
+--smart-relinquish-var` call.
+
+Signed-off-by: Denis Pynkin <denis.pynkin@collabora.com>
+---
+ units/systemd-journal-flush.service.in | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/units/systemd-journal-flush.service.in b/units/systemd-journal-flush.service.in
+index bacfe51..c10eece 100644
+--- a/units/systemd-journal-flush.service.in
++++ b/units/systemd-journal-flush.service.in
+@@ -15,6 +15,7 @@ Requires=systemd-journald.service
+ After=systemd-journald.service systemd-remount-fs.service
+ Before=systemd-tmpfiles-setup.service
+ RequiresMountsFor=/var/log/journal
++PartOf=var.mount
+ 
+ [Service]
+ ExecStart=@rootbindir@/journalctl --flush
+-- 
+2.25.4
+

debian/patches/series

@@ -84,3 +84,4 @@ sd-boot-fix-menu-ordering-with-boot-counting.patch
 apertis/0101-basic-cap-list-parse-print-numerical-capabilities.patch
 apertis/0102-basic-capability-util-let-cap_last_cap-return-unsign.patch
 apertis/0103-basic-cap-list-reduce-scope-of-variables.patch
+apertis/Force-the-call-of-systemd-journal-flush-before-var-u.patch