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.
While collecting readahead data we want to know exactly what userspace
accesses unblurred by the kernel's read_ahead_kb. Hence lower this
during collection, and raise it afterwards.
This is mostly based on ideas and code by Auke Kok.
The kernel will only notify us of cgroups running empty if no subcgroups
exist anymore. Hence make sure we don't leave our own control/ subcgroup
around longer than necessary.
https://bugzilla.redhat.com/show_bug.cgi?id=818381
RequiresMountsFor= is a shortcut for adding requires and after
dependencies to all mount units neeed for the specified paths.
This solves a couple of issues regarding dep loop cycles for encrypted
swap.
This macro comes from kernel and it's useful for unwrapping structs
inside another one. The generated code is actually the same to the one
where this logic is used in udev, but using this macro is much cleaner
and less error prone.
Two of our current job types are special:
JOB_TRY_RESTART, JOB_RELOAD_OR_START.
They differ from other job types by being sensitive to the unit active state.
They perform some action when the unit is active and some other action
otherwise. This raises a question: when exactly should the unit state be
checked to make the decision?
Currently the unit state is checked when the job becomes runnable. It's more
sensible to check the state immediately when the job is added by the user.
When the user types "systemctl try-restart foo.service", he really intends
to restart the service if it's running right now. If it isn't running right
now, the restart is pointless.
Consider the example (from Bugzilla[1]):
sleep.service takes some time to start.
hello.service has After=sleep.service.
Both services get started. Two jobs will appear:
hello.service/start waiting
sleep.service/start running
Then someone runs "systemctl try-restart hello.service".
Currently the try-restart operation will block and wait for
sleep.service/start to complete.
The correct result is to complete the try-restart operation immediately
with success, because hello.service is not running. The two original
jobs must not be disturbed by this.
To fix this we introduce two new concepts:
- a new job type: JOB_NOP
A JOB_NOP job does not do anything to the unit. It does not pull in any
dependencies. It is always immediately runnable. When installed to a unit,
it sits in a special slot (u->nop_job) where it never conflicts with
the installed job (u->job) of a different type. It never merges with jobs
of other types, but it can merge into an already installed JOB_NOP job.
- "collapsing" of job types
When a job of one of the two special types is added, the state of the unit
is checked immediately and the job type changes:
JOB_TRY_RESTART -> JOB_RESTART or JOB_NOP
JOB_RELOAD_OR_START -> JOB_RELOAD or JOB_START
Should a job type JOB_RELOAD_OR_START appear later during job merging, it
collapses immediately afterwards.
Collapsing actually makes some things simpler, because there are now fewer
job types that are allowed in the transaction.
[1] Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=753586
We shouldn't hardcode the name of the NTP implementation in the
timedated mechanism, especially since Fedora currently switched from NTP
to chrony.
This patch introduces a new target that is enabled/disabled instead of
the actual NTP implementation. The various NTP implementations should
then add .wants/ symlinks to their services and BindTo back to the
target, so that their implementations are started/stopped jointly with
the target.
https://bugzilla.redhat.com/show_bug.cgi?id=815748
Type=idle is much like Type=simple, however between the fork() and the
exec() in the child we wait until PID 1 informs us that no jobs are
left.
This is mostly a cosmetic fix to make gettys appear only after all boot
output is finished and complete.
Note that this does not impact the normal job logic as we do not delay
the completion of any jobs. We just delay the invocation of the actual
binary, and only for services that otherwise would be of Type=simple.
The ability to set MountAuto=no and SwapAuto=no was useful during the
adoption phase of systemd, so that distributions could stick to their
classic mount scripts a bit longer. It is about time to get rid of it
now.
Jobs were not preserved correctly over a daemon-reload operation.
A systemctl process waiting for a job completion received a job removal
signal. The job itself changed its id. The job timeout started ticking all
over again.
This fixes the deficiencies.
Recursion is unnecessary, because we're deleting all transaction jobs
anyway. And the recursive deletion produces debug messages that are
pointless in transaction abort.
A transaction can be acyclic, but when it's added to installed jobs,
a cycle may result.
transaction_verify_order_one() attempts to detect these cases, but it
fails because the installed jobs often have the exact generation number
that makes them look as if they were walked already.
Fix it by resetting the generation numbers of all installed jobs before
detecting cycles.
An alternative fix could be to add the generation counter to the
Manager and use it instead of starting always from 1 in
transaction_activate(). But I prefer not having to worry about it
wrapping around.
The functions looked complicated with the nested loops with breaks,
continues, and "while (again)".
Here using goto actually makes them easier to understand.
Also correcting the comment about redundant jobs.
