Yesterday we upgraded from zfs-0.6.5.3 to zfs-0.6.5.3-r3 and one of our pools got only empty folders. It imports without any problems or error messages, but after the import, only the top layer of all folders is visible and they are all empty. Today i downgraded back to zfs-0.6.5.3 and everything is back to normal without any problems. Reproducible: always with this pool
those versions are gone from the tree, closing.