This change adds ability to limit output compressed image to a certain size in blocks. We find it useful to make compressed snapshots and leave UFS snapshot metadata out. This could have some other applications as well. Posting it here mostly to get manpages checked.
This is the value he or she supplies into the -r cluster_size option (i.e. cluster_size). There is a check in the code below to make sure it's actually provided explicitly, as default size of the cluster might vary depending on the compression algorithm selected. Maybe I should replace "block" with "cluster"?