txg_handle_t
txg_handle_t tx_txgh;
extern uint64_t txg_hold_open(struct dsl_pool *dp, txg_handle_t *txghp);
extern void txg_rele_to_quiesce(txg_handle_t *txghp);
extern void txg_rele_to_sync(txg_handle_t *txghp);
extern void txg_register_callbacks(txg_handle_t *txghp, list_t *tx_callbacks);
txg_hold_open(dsl_pool_t *dp, txg_handle_t *th)
txg_rele_to_quiesce(txg_handle_t *th)
txg_register_callbacks(txg_handle_t *th, list_t *tx_callbacks)
txg_rele_to_sync(txg_handle_t *th)