ZFS filesystem size anomaly...

[Zaphod Beeblebrox]

This is all with ZFS version 6 in FreeBSD-7.1-RC, fyi...

I have a machine with the ports tree mounted in ZFS right out of the
examples:

[3:75:375]root at canoe:/usr/ports> zfs list | grep ports
canoe/ports                           3.54G  66.6G  2.35G  /usr/ports
canoe/ports/distfiles                 1.19G  66.6G  1.19G
/usr/ports/distfiles

... but the sizes here are curious.  1.2G for distfiles is about correct...
but 2.35G for the rest of ports is unreasonable.

[3:76:376]root at canoe:/usr/ports> du -hs .
1.6G    .

... saying that ports + distfiles are 1.6G.

There are no snapshots for either ports or distfiles.  There are no open
work directories.  The machine has recently rebooted.  The only directory
with more than 20M in it is distfiles --- which is the subfilesystem.

... this number 2.35G is 2G more than I expect.  Where is this space?