This makes tmpfiles, sysusers, and udevd invoked in the following order:
1. systemd-tmpfiles-setup-dev-early.service
Create device nodes gracefully, that is, create device nodes anyway
by ignoring unknown users and groups.
2. systemd-sysusers.service
Create users and groups, to make later invocations of tmpfiles and
udevd can resolve necessary users and groups.
3. systemd-tmpfiles-setup-dev.service
Adjust owners of previously created device nodes.
4. systemd-udevd.service
Process all devices. Especially to make block devices active and can
be mountable.
5. systemd-tmpfiles-setup.service
Setup basic filesystem.
Follow-up for b42482af90.
Fixes#28653.
Replaces #28681 and #28732.
local-fs-pre.target is a passive unit, which means that it is supposed to be
pulled in by everything that is ordered before it. We had
Before=local-fs-pre.target, so add Wants= too.
I don't expect this to change anything. Instead, just make things follow the
docs so it's easier to reason about the dependency set.
We want to call systemd-tmpfiles-setup-dev.service to create /dev/fuse and
other device nodes so that module probing will work. But it is possible that
when we're in first boot, some users or groups need to be created by
systemd-sysusers first. But it is also possible that systemd-sysusers cannot
actually execute configuration because the root partition is not fully writable
yet. So let systemd-tmpfiles-setup-dev.service run earlier, possibly without
all users and groups in place. Since systemd-tmpfiles-setup-dev.service writes
to /dev only, it doesn't care how the root partition is mounted. In this early
run, some some nodes might be created with default permissions (i.e. not
accessible to non-root users or groups). This should be OK for the early boot
phase. Afterwards, we let systemd-tmpfiles-setup.service execute full
configuration. We will configure any files in /dev twice, but considering that
there's only a few of them and that the second run should only adjust ownership
and permissions, this should be OK. This way, we avoid the dependency loop.
For shutdown, we queue shutdown.target/start, so in every unit which should be
stopped *before* shutdown, we need both Conflicts and an ordering dependency
with shutdown.target (either Before= or After= would work, because stop jobs
are always ordered before start jobs).
For initrd transition, we queue initrd-switch-root.service/isolate. This
automatically creates a /stop job for every running unit without
IgnoreOnIsolate. But no ordering dependency is created, unless the unit has a
(possibly transitive) ordering dependency on initrd-switch-root.service.
Since most units must stop before the transition, we should add the ordering
dependency. It is nicer to use Before=initrd-switch-root.target for this.
initrd-switch-root.target is ordered before initrd-switch-root.service, so
the effect it the same when both are in a transaction.
Fixes#23745.
To also cover the case where somebody is emergency mode in the initrd and
queues initrd-switch-root.service/start (not isolate), also add
Conflicts=initrd-switch-root.target, so various units are stopped properly.
This extends 2525682565 to cover all the other
services that are touched. It could be consider "operator error", but it's
easy to make and it's nicer if we can make this more foolproof.
The block is reordered and split to have:
1. description + documentation
2. (optionally) conditions
3. all the dependencies
I think it's easier to read the units this way.
Also, the Conflicts+Before is seperated out to separate lines.
The ordering dependency is "fake", because it could just as well be
After=, we are adding it to force ordering wrt. shutdown.target, and
it plays a different role than the other Before=, which are about a
real ordering on boot.
This makes things a bit simpler and the build a bit faster, because we don't
have to rewrite files to do the trivial substitution. @rootbindir@ is always in
our internal $PATH that we use for non-absolute paths, so there should be no
functional change.
