zdb -l doesn't show L2, L3 labels
zdb shows labels L0, L1, but L2, L3 empty.
The bug was introduced by this changes:
The reason is open64 call was moved bellow stat64 one, as result stat64 returns zero in st_size.
Because of 0 size vdev_label_offset call returns invalid value and zdb failed to read labels L2, L3
Moving open64 call above stat64 (as it was before the change) fixes the issue.