[cgmanager-devel] [cgmanager/cgmanager] cd148c: RFC: implement release-on-empty

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/cgmanager/cgmanager
  Commit: cd148ca30e6d9f0cc868e6ec322088698cc7b8c9
      https://github.com/cgmanager/cgmanager/commit/cd148ca30e6d9f0cc868e6ec322088698cc7b8c9
  Author: Serge Hallyn <serge.hallyn at ubuntu.com>
  Date:   2014-03-29 (Sat, 29 Mar 2014)

  Changed paths:
    M .gitignore
    M Makefile.am
    A acinclude.m4
    M cgm
    A cgm-release-agent.c
    M cgmanager-proxy.c
    M cgmanager.c
    M configure.ac
    M frontend.c
    M frontend.h
    M fs.c
    M fs.h
    M org.linuxcontainers.cgmanager.xml
    A tests/test21.sh

  Log Message:
  -----------
  RFC: implement release-on-empty

The new kernel mechanism for automatic removal of empty cgroups
is not yet available, therefore this uses the original
release-agent feature.  The release-agent is only told the
cgroup name being deleted, not the controller.

Cgmanager installs a program cgm-release-agent into /sbin.  It
then symlinks that to cgm-release-agent.$controller under
/run/cgmanager/agents and registers each symlink with the
related controller.  The RemoveOnEmpty dbus call causes 1 to
be written to the notify-on-release file for the specified
cgroup, so that when it becomes empty the
cgm-release-agent.$controller will be called.

As a part of this the mounting of subsystems is broken up into
collecting the subsystems, then setting release agents, and
finally mounting the subsystems into our private namespace.

Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>