dmu_tx_count_write
dmu_tx_count_write(txh, off, len);
dmu_tx_count_write(txh, off, len);
dmu_tx_count_write(txh, 0, dn->dn_datablksz);
dmu_tx_count_write(txh, off, 1);
dmu_tx_count_write(txh, off + len, 1);