ZFS uses Access Control Lists for permissions – which allows a much finer grained access structure for files. Sadly, no one else uses the ACL’s that ZFS uses (yet), and when a client writes a file over NFS, CIFS or AFP, the effective ACL’s aren’t displayed on the server. Through the power of Google, I found a blog entry with an ACL that fixes the ACL display problem.

chmod -R A=\\
owner@:w:d:allow,\\
owner@:w:f:allow,\\
everyone@:rxpdDaARWcCos:d:allow,\\
everyone@:rpdDaARWcCos:f:allow \\
/tank