There is no need to restrict this to only the 'nofail' case. In the '!nofail'
case the unit is already wanted by swap.target, so this is not a functional change.
Replace the very generic cgroup hookup with a much simpler one. With
this change only the high-level cgroup settings remain, the ability to
set arbitrary cgroup attributes is removed, so is support for adding
units to arbitrary cgroup controllers or setting arbitrary paths for
them (especially paths that are different for the various controllers).
This also introduces a new -.slice root slice, that is the parent of
system.slice and friends. This enables easy admin configuration of
root-level cgrouo properties.
This replaces DeviceDeny= by DevicePolicy=, and implicitly adds in
/dev/null, /dev/zero and friends if DeviceAllow= is used (unless this is
turned off by DevicePolicy=).
In order to prepare for the kernel cgroup rework, let's introduce a new
unit type to systemd, the "slice". Slices can be arranged in a tree and
are useful to partition resources freely and hierarchally by the user.
Each service unit can now be assigned to one of these slices, and later
on login users and machines may too.
Slices translate pretty directly to the cgroup hierarchy, and the
various objects can be assigned to any of the slices in the tree.
I'm assuming that it's fine if a _const_ or _pure_ function
calls assert. It is assumed that the assert won't trigger,
and even if it does, it can only trigger on the first call
with a given set of parameters, and we don't care if the
compiler moves the order of calls.
Before, we would initialize many fields twice: first
by filling the structure with zeros, and then a second
time with the real values. We can let the compiler do
the job for us, avoiding one copy.
A downside of this patch is that text gets slightly
bigger. This is because all zero() calls are effectively
inlined:
$ size build/.libs/systemd
text data bss dec hex filename
before 897737 107300 2560 1007597 f5fed build/.libs/systemd
after 897873 107300 2560 1007733 f6075 build/.libs/systemd
… actually less than 1‰.
A few asserts that the parameter is not null had to be removed. I
don't think this changes much, because first, it is quite unlikely
for the assert to fail, and second, an immediate SEGV is almost as
good as an assert.
All Execs within the service, will get mounted the same
/tmp and /var/tmp directories, if service is configured with
PrivateTmp=yes. Temporary directories are cleaned up by service
itself in addition to systemd-tmpfiles. Directory which is mounted
as inaccessible is created at runtime in /run/systemd.
There are very few differences in the implementations of the kill method in the
unit types that have one. Let's unify them.
This does not yet unify unit_kill() with unit_kill_context().
Starting a swap unit pointing to (What) a symlink (e.g. /dev/mapper/swap
or /dev/disk/by-uuid/...) would have said unit marked active, following
the one using the "actual" device (/dev/{dm-1,sda3}), but that new unit
would be seen as inactive.
Since all requests to stop swap units would follow/redirect to it,
and it is seen inactive, nothing would be done (swapoff never called).
This is because this unit would be treated twice in
swap_process_new_swap, the second call to swap_add_one causing it to
eventually be marked inactive.
The fstab generator adds Before=swap.target by default, and when creating
a custom .swap unit, you can also add Before=swap.target to the unit.
However, it is impossible to not have this ordering dependency right now.
Virtually all existing setups likely use the fstab generator, so this
change is unlikely to break anything.
Note: I did s/MANAGER/SYSTEMD/ everywhere, even though it makes the
patch quite verbose. Nevertheless, keeping MANAGER prefix in some
places, and SYSTEMD prefix in others would just lead to confusion down
the road. Better to rip off the band-aid now.
In some cases, like wrong configuration, restarting after error
does not help, so administrator can specify statuses by RestartPreventExitStatus
which will not cause restart of a service.
Sometimes you have non-standart exit status, so this can be specified
by SuccessfulExitStatus.
