Format 2: Use indices rather than subtree scanning

Institute the format 2 cache type.  Rather than scanning the directory tree
each time to find objects to cull, instead make use of index files maintained
by the format 2 kernel facility.

Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
7 files changed