diff --git a/module/zfs/dmu_tx.c b/module/zfs/dmu_tx.c
index 42ce01d23c..18a640d6d0 100644
--- a/module/zfs/dmu_tx.c
+++ b/module/zfs/dmu_tx.c
@@ -48,8 +48,6 @@ dmu_tx_create_dd(dsl_dir_t *dd)
 		tx->tx_pool = dd->dd_pool;
 	list_create(&tx->tx_holds, sizeof (dmu_tx_hold_t),
 	    offsetof(dmu_tx_hold_t, txh_node));
-	list_create(&tx->tx_callbacks, sizeof (dmu_callback_t),
-	    offsetof(dmu_callback_t, dcb_node));
 #ifdef ZFS_DEBUG
 	refcount_create(&tx->tx_space_written);
 	refcount_create(&tx->tx_space_freed);
@@ -1022,9 +1020,6 @@ dmu_tx_commit(dmu_tx_t *tx)
 	if (tx->tx_tempreserve_cookie)
 		dsl_dir_tempreserve_clear(tx->tx_tempreserve_cookie, tx);
 
-	if (!list_is_empty(&tx->tx_callbacks))
-		txg_rele_commit_cb(&tx->tx_txgh, &tx->tx_callbacks);
-
 	if (tx->tx_anyobj == FALSE)
 		txg_rele_to_sync(&tx->tx_txgh);
 	list_destroy(&tx->tx_holds);
@@ -1037,8 +1032,6 @@ dmu_tx_commit(dmu_tx_t *tx)
 	refcount_destroy_many(&tx->tx_space_freed,
 	    refcount_count(&tx->tx_space_freed));
 #endif
-	ASSERT(list_is_empty(&tx->tx_callbacks));
-	list_destroy(&tx->tx_callbacks);
 	kmem_free(tx, sizeof (dmu_tx_t));
 }
 
@@ -1046,7 +1039,6 @@ void
 dmu_tx_abort(dmu_tx_t *tx)
 {
 	dmu_tx_hold_t *txh;
-	dmu_callback_t *dcb;
 
 	ASSERT(tx->tx_txg == 0);
 
@@ -1058,16 +1050,6 @@ dmu_tx_abort(dmu_tx_t *tx)
 		if (dn != NULL)
 			dnode_rele(dn, tx);
 	}
-
-	while ((dcb = list_head(&tx->tx_callbacks))) {
-		list_remove(&tx->tx_callbacks, dcb);
-
-		/*
-		 * Call the callback with an error code. The callback will
-		 * call dmu_tx_callback_data_destroy to free the memory.
-		 */
-		dcb->dcb_func(dcb->dcb_data, ECANCELED);
-	}
 	list_destroy(&tx->tx_holds);
 #ifdef ZFS_DEBUG
 	refcount_destroy_many(&tx->tx_space_written,
@@ -1075,7 +1057,6 @@ dmu_tx_abort(dmu_tx_t *tx)
 	refcount_destroy_many(&tx->tx_space_freed,
 	    refcount_count(&tx->tx_space_freed));
 #endif
-	list_destroy(&tx->tx_callbacks);
 	kmem_free(tx, sizeof (dmu_tx_t));
 }
 
@@ -1085,45 +1066,3 @@ dmu_tx_get_txg(dmu_tx_t *tx)
 	ASSERT(tx->tx_txg != 0);
 	return (tx->tx_txg);
 }
-
-void *
-dmu_tx_callback_data_create(size_t bytes)
-{
-	dmu_callback_t *dcb;
-
-	dcb = kmem_alloc(sizeof (dmu_callback_t) + bytes, KM_SLEEP);
-
-	dcb->dcb_magic = DMU_CALLBACK_MAGIC;
-	dcb->dcb_bytes = bytes;
-
-	return &dcb->dcb_data;
-}
-
-int
-dmu_tx_callback_commit_add(dmu_tx_t *tx, dmu_callback_func_t *dcb_func,
-    void *dcb_data)
-{
-	dmu_callback_t *dcb = container_of(dcb_data, dmu_callback_t, dcb_data);
-
-	if (dcb->dcb_magic != DMU_CALLBACK_MAGIC)
-		return (EINVAL);
-
-	dcb->dcb_func = dcb_func;
-
-	list_insert_tail(&tx->tx_callbacks, dcb);
-
-	return (0);
-}
-
-int
-dmu_tx_callback_data_destroy(void *dcb_data)
-{
-	dmu_callback_t *dcb = container_of(dcb_data, dmu_callback_t, dcb_data);
-
-	if (dcb->dcb_magic != DMU_CALLBACK_MAGIC)
-		return (EINVAL);
-
-	kmem_free(dcb, sizeof (dmu_callback_t) + dcb->dcb_bytes);
-
-	return (0);
-}
diff --git a/module/zfs/include/sys/dmu.h b/module/zfs/include/sys/dmu.h
index e4bcdfbe03..3b1e5c8fbc 100644
--- a/module/zfs/include/sys/dmu.h
+++ b/module/zfs/include/sys/dmu.h
@@ -64,7 +64,6 @@ struct objset_impl;
 typedef struct objset objset_t;
 typedef struct dmu_tx dmu_tx_t;
 typedef struct dsl_dir dsl_dir_t;
-typedef void dmu_callback_func_t(void *dcb_data, int error);
 
 typedef enum dmu_object_type {
 	DMU_OT_NONE,
@@ -430,32 +429,6 @@ int dmu_tx_assign(dmu_tx_t *tx, uint64_t txg_how);
 void dmu_tx_wait(dmu_tx_t *tx);
 void dmu_tx_commit(dmu_tx_t *tx);
 
-/*
- * To add a commit callback, you must first call dmu_tx_callback_data_create().
- * This will return a pointer to a memory area of size "bytes" (which can be 0,
- * or just the size of a pointer if there is a large or existing external data
- * struct to be referenced) that the caller and the callback can use to exchange
- * data.
- *
- * The callback can then be registered by calling dmu_tx_callback_commit_add()
- * with the pointer returned by dmu_tx_callback_data_create() passed in the
- * dcb_data argument. The transaction must be already created, but it cannot
- * be committed or aborted. It can be assigned to a txg or not.
- *
- * The callback will be called after the transaction has been safely written
- * to stable storage and will also be called if the dmu_tx is aborted.
- * If there is any error which prevents the transaction from being committed
- * to disk, the callback will be called with a value of error != 0.
- *
- * When the callback data is no longer needed, it must be destroyed by the
- * caller's code with dmu_tx_callback_data_destroy(). This is typically done at
- * the end of the callback function.
- */
-void *dmu_tx_callback_data_create(size_t bytes);
-int dmu_tx_callback_commit_add(dmu_tx_t *tx, dmu_callback_func_t *dcb_func,
-    void *dcb_data);
-int dmu_tx_callback_data_destroy(void *dcb_data);
-
 /*
  * Free up the data blocks for a defined range of a file.  If size is
  * zero, the range from offset to end-of-file is freed.
diff --git a/module/zfs/include/sys/dmu_impl.h b/module/zfs/include/sys/dmu_impl.h
index f32ab6ad71..96ce688e15 100644
--- a/module/zfs/include/sys/dmu_impl.h
+++ b/module/zfs/include/sys/dmu_impl.h
@@ -232,19 +232,6 @@ extern "C" {
 struct objset;
 struct dmu_pool;
 
-#define DMU_CALLBACK_MAGIC 0xca11bac0ca11bacfull
-
-#define container_of(ptr, type, member) \
-    ((type *)((char *)(ptr) - offsetof(type, member)))
-
-typedef struct dmu_callback {
-	list_node_t         dcb_node;    /* linked to tx_callbacks list */
-	uint64_t            dcb_magic;   /* magic number to verify header */
-	dmu_callback_func_t *dcb_func;   /* caller function pointer */
-	size_t              dcb_bytes;   /* caller private data size */
-	char                dcb_data[0]; /* caller private data */
-} dmu_callback_t;
-
 #ifdef	__cplusplus
 }
 #endif
diff --git a/module/zfs/include/sys/dmu_tx.h b/module/zfs/include/sys/dmu_tx.h
index 47b9bcaa57..2727daaaa7 100644
--- a/module/zfs/include/sys/dmu_tx.h
+++ b/module/zfs/include/sys/dmu_tx.h
@@ -59,7 +59,6 @@ struct dmu_tx {
 	txg_handle_t tx_txgh;
 	void *tx_tempreserve_cookie;
 	struct dmu_tx_hold *tx_needassign_txh;
-	list_t tx_callbacks; /* list of dmu_callback_t on this dmu_tx */
 	uint8_t tx_anyobj;
 	int tx_err;
 #ifdef ZFS_DEBUG
@@ -110,11 +109,6 @@ void dmu_tx_abort(dmu_tx_t *tx);
 uint64_t dmu_tx_get_txg(dmu_tx_t *tx);
 void dmu_tx_wait(dmu_tx_t *tx);
 
-void *dmu_tx_callback_data_create(size_t bytes);
-int dmu_tx_callback_commit_add(dmu_tx_t *tx, dmu_callback_func_t *dcb_func,
-    void *dcb_data);
-int dmu_tx_callback_data_destroy(void *dcb_data);
-
 /*
  * These routines are defined in dmu_spa.h, and are called by the SPA.
  */
diff --git a/module/zfs/include/sys/txg.h b/module/zfs/include/sys/txg.h
index 1349bd4dcb..23bdff211b 100644
--- a/module/zfs/include/sys/txg.h
+++ b/module/zfs/include/sys/txg.h
@@ -71,7 +71,6 @@ extern void txg_sync_stop(struct dsl_pool *dp);
 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_rele_commit_cb(txg_handle_t *txghp, list_t *tx_callbacks);
 extern void txg_suspend(struct dsl_pool *dp);
 extern void txg_resume(struct dsl_pool *dp);
 
diff --git a/module/zfs/include/sys/txg_impl.h b/module/zfs/include/sys/txg_impl.h
index a9a7c358b4..7413c662b3 100644
--- a/module/zfs/include/sys/txg_impl.h
+++ b/module/zfs/include/sys/txg_impl.h
@@ -37,7 +37,6 @@ struct tx_cpu {
 	kmutex_t	tc_lock;
 	kcondvar_t	tc_cv[TXG_SIZE];
 	uint64_t	tc_count[TXG_SIZE];
-	list_t		tc_callbacks[TXG_SIZE]; /* post-commit callbacks */
 	char		tc_pad[16];
 };
 
diff --git a/module/zfs/txg.c b/module/zfs/txg.c
index ddd3543f89..2ba3b20dd0 100644
--- a/module/zfs/txg.c
+++ b/module/zfs/txg.c
@@ -26,7 +26,6 @@
 #include <sys/zfs_context.h>
 #include <sys/txg_impl.h>
 #include <sys/dmu_impl.h>
-#include <sys/dmu_tx.h>
 #include <sys/dsl_pool.h>
 #include <sys/callb.h>
 
@@ -58,9 +57,6 @@ txg_init(dsl_pool_t *dp, uint64_t txg)
 		for (i = 0; i < TXG_SIZE; i++) {
 			cv_init(&tx->tx_cpu[c].tc_cv[i], NULL, CV_DEFAULT,
 			    NULL);
-			list_create(&tx->tx_cpu[c].tc_callbacks[i],
-			    sizeof (dmu_callback_t), offsetof(dmu_callback_t,
-			    dcb_node));
 		}
 	}
 
@@ -102,11 +98,8 @@ txg_fini(dsl_pool_t *dp)
 		int i;
 
 		mutex_destroy(&tx->tx_cpu[c].tc_lock);
-		for (i = 0; i < TXG_SIZE; i++) {
+		for (i = 0; i < TXG_SIZE; i++)
 			cv_destroy(&tx->tx_cpu[c].tc_cv[i]);
-			ASSERT(list_is_empty(&tx->tx_cpu[c].tc_callbacks[i]));
-			list_destroy(&tx->tx_cpu[c].tc_callbacks[i]);
-		}
 	}
 
 	kmem_free(tx->tx_cpu, max_ncpus * sizeof (tx_cpu_t));
@@ -252,21 +245,6 @@ txg_rele_to_sync(txg_handle_t *th)
 	th->th_cpu = NULL;	/* defensive */
 }
 
-void
-txg_rele_commit_cb(txg_handle_t *th, list_t *tx_callbacks)
-{
-	dmu_callback_t *dcb;
-	tx_cpu_t *tc = th->th_cpu;
-	int g = th->th_txg & TXG_MASK;
-
-	mutex_enter(&tc->tc_lock);
-	while ((dcb = list_head(tx_callbacks))) {
-		list_remove(tx_callbacks, dcb);
-		list_insert_tail(&tc->tc_callbacks[g], dcb);
-	}
-	mutex_exit(&tc->tc_lock);
-}
-
 static void
 txg_quiesce(dsl_pool_t *dp, uint64_t txg)
 {
@@ -307,15 +285,14 @@ txg_sync_thread(dsl_pool_t *dp)
 {
 	tx_state_t *tx = &dp->dp_tx;
 	callb_cpr_t cpr;
-	uint64_t timeout, start, delta, timer;
-	int c, target;
+	uint64_t start, delta;
 
 	txg_thread_enter(tx, &cpr);
 
 	start = delta = 0;
 	for (;;) {
 		uint64_t timer, timeout = zfs_txg_timeout * hz;
-		uint64_t txg, written;
+		uint64_t txg;
 
 		/*
 		 * We sync when we're scrubbing, there's someone waiting
@@ -370,63 +347,6 @@ txg_sync_thread(dsl_pool_t *dp)
 		spa_sync(dp->dp_spa, txg);
 		delta = lbolt - start;
 
-		/*
-		 * Call all the callbacks for this txg. The callbacks must
-		 * call dmu_tx_callback_data_destroy to free memory.
-		 */
-		for (c = 0; c < max_ncpus; c++) {
-			dmu_callback_t *dcb;
-			tx_cpu_t *tc = &tx->tx_cpu[c];
-			int g = txg & TXG_MASK;
-			/* No need to lock tx_cpu_t */
-
-			while ((dcb = list_head(&tc->tc_callbacks[g]))) {
-				list_remove(&tc->tc_callbacks[g], dcb);
-				dcb->dcb_func(dcb->dcb_data, 0);
-			}
-		}
-
-		written = dp->dp_space_towrite[txg & TXG_MASK];
-		dp->dp_space_towrite[txg & TXG_MASK] = 0;
-		ASSERT(dp->dp_tempreserved[txg & TXG_MASK] == 0);
-
-		/*
-		 * If the write limit max has not been explicitly set, set it
-		 * to a fraction of available phisical memory (default 1/8th).
-		 * Note that we must inflate the limit because the spa
-		 * inflates write sizes to account for data replication.
-		 * Check this each sync phase to catch changing memory size.
-		 */
-		if (zfs_write_limit_inflated == 0 ||
-		    (zfs_write_limit_shift && zfs_write_limit_max !=
-		    physmem * PAGESIZE >> zfs_write_limit_shift)) {
-			zfs_write_limit_max =
-			    physmem * PAGESIZE >> zfs_write_limit_shift;
-			zfs_write_limit_inflated =
-			    spa_get_asize(dp->dp_spa, zfs_write_limit_max);
-			if (zfs_write_limit_min > zfs_write_limit_inflated)
-				zfs_write_limit_inflated = zfs_write_limit_min;
-		}
-
-		/*
-		 * Attempt to keep the sync time consistant by adjusting the
-		 * amount of write traffic allowed into each transaction group.
-		 */
-		target = zfs_txg_synctime * hz;
-		if (delta > target) {
-			uint64_t old = MIN(dp->dp_write_limit, written);
-
-			dp->dp_write_limit = MAX(zfs_write_limit_min,
-			    old * target / delta);
-		} else if (written >= dp->dp_write_limit &&
-		    delta >> 3 < target >> 3) {
-			uint64_t rescale =
-			    MIN((100 * target) / delta, 200);
-
-			dp->dp_write_limit = MIN(zfs_write_limit_inflated,
-			    written * rescale / 100);
-		}
-
 		mutex_enter(&tx->tx_sync_lock);
 		rw_enter(&tx->tx_suspend, RW_WRITER);
 		tx->tx_synced_txg = txg;