Cause: In RHEL 6.4, libvirt started caching storage file backing chains. However, the code only populated the cache when cgroups were in use.
Consequence: Without cgroups, a missing cache meant sVirt was unable to properly label backing chain files, preventing guest startup.
Fix: Populating the cache was moved earlier, independent of cgroups.
Result: More efficient sVirt operations, regardless of cgroups.