ZFS list -t snapshot USAGE column

[Lorenzo Perone]

Hi there,

just wondering, since the ZFS v13 update (to be precise, 7.2-STABLE  
FreeBSD 7.2-STABLE #11: Wed Jun  3 23:11:29 CEST 2009) why the USAGE  
column in a zfs list -t snapshot is not showing anymore the space used  
by the snapshot? I made those snapshots with zfs snapshot -r.

They're almost all showing a USAGE of 0K, albeit there have been  
changes to the dataset since that snapshot.

Regards,

Lorenzo