Show sparse usage.

[ghost]

It would be good if sparse holes are shown as it's own row instead of baked in with "none".

# touch file
# fallocate -l 100M file
# compsize file
Type       Perc     Disk Usage   Uncompressed Referenced
TOTAL      100%      100M         100M         100M
none       100%      100M         100M         100M

[kilobyte]

These are no holes — compsize doesn't display those at all, otherwise a single 1PB file would dwarf everything else. But handling preallocated extents as if they were a separate compression type is reasonable.