At the moment the only usable large_dnode feature support is from
zfsonlinux implementation, so the way to test this update is to create
pool and test the reader.
tested with: zfs set dnsize=auto and then did copy some data into dataset, checked which files got dnsize > 512 and verified the loader can read those files.
also zfs set dnsize=1k, did use setfattr to set value < 512 and value > 1k, to verify file without and with spill blocks. At this time it is not entirely clear about howThe pool and dataset setup was done with zol rescue ISO, read test with loader.efi.
we can reliably identify the large_dnode usage, therefore more testing
and investigation is needed.