NFSv4 & ZFS question

[Peter Hodur]

Hello,

just starting and migrating storage server from NFSv3 to NFSv4. I have read
everything including man nfsv4 and found this:

..............
 The
     nfsd(8) allows a limited subset of operations to be performed on non-
     exported subtrees of the local file system, so that traversal of the
tree
     to the exported subtrees is possible.  As such, the ``<rootdir>'' can
be
     in a non-exported file system.  The exception is ZFS, which checks
     exports and, as such, all ZFS file systems below the ``<rootdir>'' must
     be exported.  However, the entire tree that is rooted at that point
must
     be in local file systems that are of types that can be NFS exported.
     Since the NFSv4 file system is rooted at ``<rootdir>'', setting this to
     anything other than ``/'' will result in clients being required to use
     different mount paths for NFSv4 than for NFS Version 2 or 3.  Unlike
NFS
     Version 2 and 3, Version 4 allows a client mount to span across
multiple
     server file systems, although not all clients are capable of doing
this.
..................

How can I understand:

"The exception is ZFS, which checks exports and, as such, all ZFS file
systems below the `<rootdir>'' must be exported."

Why? So when I add "V4: /" in /etc/exports then I must export ALL
(including zroot) filesystems? Is this bug or it is true and is better to
make /exports a below this directory move all "shared filesystems"?


thanks

Peter