Improvement based on code review.

Switch back to tx_quiesce_more_cv for txg_kick().

Signed-off-by: jxdking <[email protected]>

module/zfs/txg.c

@@ -498,6 +498,14 @@ txg_wait_callbacks(dsl_pool_t *dp)
 		taskq_wait_outstanding(tx->tx_commit_cb_taskq, 0);
 }
 
+static boolean_t
+txg_is_syncing(dsl_pool_t *dp)
+{
+	tx_state_t *tx = &dp->dp_tx;
+	ASSERT(MUTEX_HELD(&tx->tx_sync_lock));
+	return (tx->tx_syncing_txg != 0);
+}
+
 static boolean_t
 txg_is_quiescing(dsl_pool_t *dp)
 {
@@ -794,13 +802,26 @@ txg_kick(dsl_pool_t *dp, uint64_t txg)
 
 	ASSERT(!dsl_pool_config_held(dp));
 
+	/* Fast return path outside tx_sync_lock */
 	if (tx->tx_sync_txg_waiting >= txg)
 		return;
 
 	mutex_enter(&tx->tx_sync_lock);
 	if (tx->tx_sync_txg_waiting < txg) {
+
+		/*
+		 * Always update tx_sync_txg_waiting, so that even if kick
+		 * condition below is not applicable, this txg will be picked
+		 * up by sync thread eventually.
+		 */
 		tx->tx_sync_txg_waiting = txg;
-		cv_broadcast(&tx->tx_sync_more_cv);
+
+		if (!txg_is_syncing(dp) &&
+		    !txg_is_quiescing(dp) &&
+		    tx->tx_quiesce_txg_waiting <= txg) {
+			tx->tx_quiesce_txg_waiting = txg + 1;
+			cv_broadcast(&tx->tx_quiesce_more_cv);
+		}
 	}
 	mutex_exit(&tx->tx_sync_lock);
 }