If the inode nr for each file is available in the pack file we can
easily detect replaced files (like they result from package upgrades)
which we can then skip to readahead.
In some cases the main/control PID of a service can be outside of the
services cgroups (for example, if logind readjusts the processes'
cgroup). In order to clarify this for the user show the main/control PID
in the cgroup tree nonetheless, but mark them specially.
Previously, we were brutally and onconditionally killing all processes
in a service's cgroup before starting the service anew, in order to
ensure that StartPre lines cannot be misused to spawn long-running
processes.
On logind-less systems this has the effect that restarting sshd
necessarily calls all active ssh sessions, which is usually not
desirable.
With this patch control processes for a service are placed in a
sub-cgroup called "control/". When starting a service anew we simply
kill this cgroup, but not the main cgroup, in order to avoid killing any
long-running non-control processes from previous runs.
https://bugzilla.redhat.com/show_bug.cgi?id=805942
gettys are nowadays mostly autospawned and hence usually subject to
being shut down on isolate requests, since they are no dependency of any
other unit. This is a bad idea if the user isolates between
multi-user.graphical and graphical.target, hence exclude them from the
isolation.
This has the effect that gettys no longer cleaned up when
emergency.target is isolated, which might actualy be considered a
feature, even though it is a change from previous behaviour...
Note that the one getty that really matters (the one on tty1) is still
removed when isolating to emergency.target since it conflicts with
emergency.service.
