dbuf_assign_arcbuf
dbuf_assign_arcbuf(dstdb, abuf, tx);
dbuf_assign_arcbuf(db, buf, tx);
dbuf_assign_arcbuf((dmu_buf_impl_t *)db_spill, abuf, tx);
void dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx);