hammer2_io_getblk
*diop = hammer2_io_getblk(hmp, btype, lbase, lsize, HAMMER2_DOP_NEW);
*diop = hammer2_io_getblk(hmp, btype, lbase, lsize, HAMMER2_DOP_NEWNZ);
*diop = hammer2_io_getblk(hmp, btype, lbase, lsize, HAMMER2_DOP_NEW);
*diop = hammer2_io_getblk(hmp, btype, lbase, lsize, HAMMER2_DOP_NEWNZ);