Index: spa.c
===================================================================
--- spa.c	(revision 253644)
+++ spa.c	(working copy)
@@ -5763,6 +5763,7 @@ spa_async_thread(void *arg)
 
 	mutex_enter(&spa->spa_async_lock);
 	tasks = spa->spa_async_tasks;
+retry:
 	spa->spa_async_tasks = 0;
 	mutex_exit(&spa->spa_async_lock);
 
@@ -5833,6 +5834,9 @@ spa_async_thread(void *arg)
 	 * Let the world know that we're done.
 	 */
 	mutex_enter(&spa->spa_async_lock);
+	tasks = spa->spa_async_tasks;
+	if ((tasks & SPA_ASYNC_REMOVE) != 0)
+		goto retry;
 	spa->spa_async_thread = NULL;
 	cv_broadcast(&spa->spa_async_cv);
 	mutex_exit(&spa->spa_async_lock);
@@ -5898,6 +5902,9 @@ spa_async_request(spa_t *spa, int task)
 	mutex_enter(&spa->spa_async_lock);
 	spa->spa_async_tasks |= task;
 	mutex_exit(&spa->spa_async_lock);
+	if ((task & SPA_ASYNC_REMOVE) != 0 &&
+	    spa->spa_state != POOL_STATE_UNINITIALIZED)
+		spa_async_dispatch(spa);
 }
 
 /*