Allow configuring the overlay snapshotter to synchronously
or asynchronously do cleanup. When the driver is integrated
into a garbage collection system, the asynchronous cleanup
can reduce the time of removal and allow the longer disk
cleanup to be handled without locking the snapshotter.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
Updates overlay remove to simply remove the reference, adds
a cleanup method for discarding the directory.
Updates snapshot create to setup the directory structure while
in the transaction, to prevent cleanup from removing directories
which are part of a create.
Signed-off-by: Derek McGowan <derek@mcgstyle.net>
