device_path_make_{major_minor|canonical) generate device node paths
given a mode_t and a dev_t. We have similar code all over the place,
let's unify this in one place. The former will generate a "/dev/char/"
or "/dev/block" path, and never go to disk. The latter then goes to disk
and resolves that path to the actual path of the device node.
device_path_parse_major_minor() reverses device_path_make_major_minor(),
also withozut going to disk.
We have similar code doing something like this at various places, let's
unify this in a single set of functions. This also allows us to teach
them special tricks, for example handling of the
/run/systemd/inaccessible/{blk|chr} device nodes, which we use for
masking device nodes, and which do not exist in /dev/char/* and
/dev/block/*
We should probably drop path_join() entirely in the long run (and
then rename path_join_many() to it?), but for now let's make one a
wrapper for the other.
Let's be a bit more careful when parsing major/minor pairs, and filter
out more corner cases. This also means using safe_atou() rather than
sscanf() to avoid weird negative unsigned handling and such.
As it turns out glibc and the Linux kernel have different ideas about
the size of dev_t and how many bits exist for the major and the minor.
When validating major/minor numbers we should check against the kernel's
actual sizes, hence add macros for this.
Let's simplify things and drop the logic that /var/lib/machines is setup
as auto-growing btrfs loopback file /var/lib/machines.raw.
THis was done in order to make quota available for machine management,
but quite frankly never really worked properly, as we couldn't grow the
file system in sync with its use properly. Moreover philosophically it's
problematic overriding the admin's choice of file system like this.
Let's hence drop this, and simplify things. Deleting code is a good
feeling.
Now that regular file systems provide project quota we could probably
add per-machine quota support based on that, hence the btrfs quota
argument is not that interesting anymore (though btrfs quota is a bit
more powerful as it allows recursive quota, i.e. that the machine pool
gets an overall quota in addition to per-machine quota).
Fixes: #2728
This is also supposed to be preparation for doing #10234 eventually,
where a very similar operation is requested: instead of importing a tree
to /var/lib/machines it would need to be imported into
/var/lib/portables/.
This adds two optional functions that may be passed to the various copy
functions. One is invoked whenever we start copying a new file object,
the other while we copy file payload in each loop iteration.
When the caller passes one or both they can get notifications about copy
progress, for example to log where things are.
This is to startswith() what PATH_STARTSWITH_SET() is to
path_startswith().
Or in other words, checks if the specified string has any of the listed
prefixes, and if so, returns the remainder of the string.
This changes cg_enable_everywhere() to return which controllers are
enabled for the specified cgroup. This information is then used to
correctly track the enablement mask currently in effect for a unit.
Moreover, when we try to turn off a controller, and this works, then
this is indicates that the parent unit might succesfully turn it off
now, too as our unit might have kept it busy.
So far, when realizing cgroups, i.e. when syncing up the kernel
representation of relevant cgroups with our own idea we would strictly
work from the root to the leaves. This is generally a good approach, as
when controllers are enabled this has to happen in root-to-leaves order.
However, when controllers are disabled this has to happen in the
opposite order: in leaves-to-root order (this is because controllers can
only be enabled in a child if it is already enabled in the parent, and
if it shall be disabled in the parent then it has to be disabled in the
child first, otherwise it is considered busy when it is attempted to
remove it in the parent).
To make things complicated when invalidating a unit's cgroup membershup
systemd can actually turn off some controllers previously turned on at
the very same time as it turns on other controllers previously turned
off. In such a case we have to work up leaves-to-root *and*
root-to-leaves right after each other. With this patch this is
implemented: we still generally operate root-to-leaves, but as soon as
we noticed we successfully turned off a controller previously turned on
for a cgroup we'll re-enqueue the cgroup realization for all parents of
a unit, thus implementing leaves-to-root where necessary.
Lennart Poettering
Zbigniew Jędrzejewski-Szmek
Yu Watanabe
Susant Sahani