bb_header_ext_t
bb_header_ext_t *ext_header;
ext_header = (bb_header_ext_t *)extra;
cksum = compute_checksum(extra + sizeof (bb_header_ext_t),
einfo = (bblk_einfo_t *)(extra + sizeof (bb_header_ext_t));
bb_header_ext_t *ext_hdr;
ext_hdr = (bb_header_ext_t *)extra;