diff --git a/cmd/ztest/ztest.c b/cmd/ztest/ztest.c
index a2568962d8..a99f60964a 100644
--- a/cmd/ztest/ztest.c
+++ b/cmd/ztest/ztest.c
@@ -1189,10 +1189,10 @@ ztest_kill(ztest_shared_t *zs)
 	(void) kill(getpid(), SIGKILL);
 }
 
-/* ARGSUSED */
 static void
 ztest_record_enospc(const char *s)
 {
+	(void) s;
 	ztest_shared->zs_enospc_count++;
 }
 
@@ -2389,10 +2389,10 @@ zil_replay_func_t *ztest_replay_vector[TX_MAX_TYPE] = {
  * ZIL get_data callbacks
  */
 
-/* ARGSUSED */
 static void
 ztest_get_done(zgd_t *zgd, int error)
 {
+	(void) error;
 	ztest_ds_t *zd = zgd->zgd_private;
 	uint64_t object = ((rl_t *)zgd->zgd_lr)->rl_object;
 
@@ -2409,6 +2409,7 @@ static int
 ztest_get_data(void *arg, uint64_t arg2, lr_write_t *lr, char *buf,
     struct lwb *lwb, zio_t *zio)
 {
+	(void) arg2;
 	ztest_ds_t *zd = arg;
 	objset_t *os = zd->zd_os;
 	uint64_t object = lr->lr_foid;
@@ -2869,10 +2870,10 @@ ztest_object_init(ztest_ds_t *zd, ztest_od_t *od, size_t size, boolean_t remove)
 	return (rv);
 }
 
-/* ARGSUSED */
 void
 ztest_zil_commit(ztest_ds_t *zd, uint64_t id)
 {
+	(void) id;
 	zilog_t *zilog = zd->zd_zilog;
 
 	(void) pthread_rwlock_rdlock(&zd->zd_zilog_lock);
@@ -2898,10 +2899,10 @@ ztest_zil_commit(ztest_ds_t *zd, uint64_t id)
  * mount/unmount operation.  We hold the dataset across these operations in an
  * attempt to expose any implicit assumptions about ZIL management.
  */
-/* ARGSUSED */
 void
 ztest_zil_remount(ztest_ds_t *zd, uint64_t id)
 {
+	(void) id;
 	objset_t *os = zd->zd_os;
 
 	/*
@@ -2935,10 +2936,10 @@ ztest_zil_remount(ztest_ds_t *zd, uint64_t id)
  * Verify that we can't destroy an active pool, create an existing pool,
  * or create a pool with a bad vdev spec.
  */
-/* ARGSUSED */
 void
 ztest_spa_create_destroy(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	ztest_shared_opts_t *zo = &ztest_opts;
 	spa_t *spa;
 	nvlist_t *nvroot;
@@ -2998,10 +2999,10 @@ ztest_spa_create_destroy(ztest_ds_t *zd, uint64_t id)
  * Start and then stop the MMP threads to ensure the startup and shutdown code
  * works properly.  Actual protection and property-related code tested via ZTS.
  */
-/* ARGSUSED */
 void
 ztest_mmp_enable_disable(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	ztest_shared_opts_t *zo = &ztest_opts;
 	spa_t *spa = ztest_spa;
 
@@ -3044,10 +3045,10 @@ ztest_mmp_enable_disable(ztest_ds_t *zd, uint64_t id)
 	spa_config_exit(spa, SCL_CONFIG, FTAG);
 }
 
-/* ARGSUSED */
 void
 ztest_spa_upgrade(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	spa_t *spa;
 	uint64_t initial_version = SPA_VERSION_INITIAL;
 	uint64_t version, newversion;
@@ -3164,10 +3165,10 @@ ztest_spa_discard_checkpoint(spa_t *spa)
 
 }
 
-/* ARGSUSED */
 void
 ztest_spa_checkpoint_create_discard(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	spa_t *spa = ztest_spa;
 
 	mutex_enter(&ztest_checkpoint_lock);
@@ -3208,10 +3209,10 @@ spa_num_top_vdevs(spa_t *spa)
 /*
  * Verify that vdev_add() works as expected.
  */
-/* ARGSUSED */
 void
 ztest_vdev_add_remove(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	ztest_shared_t *zs = ztest_shared;
 	spa_t *spa = ztest_spa;
 	uint64_t leaves;
@@ -3298,10 +3299,10 @@ ztest_vdev_add_remove(ztest_ds_t *zd, uint64_t id)
 	mutex_exit(&ztest_vdev_lock);
 }
 
-/* ARGSUSED */
 void
 ztest_vdev_class_add(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	ztest_shared_t *zs = ztest_shared;
 	spa_t *spa = ztest_spa;
 	uint64_t leaves;
@@ -3379,10 +3380,10 @@ ztest_vdev_class_add(ztest_ds_t *zd, uint64_t id)
 /*
  * Verify that adding/removing aux devices (l2arc, hot spare) works as expected.
  */
-/* ARGSUSED */
 void
 ztest_vdev_aux_add_remove(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	ztest_shared_t *zs = ztest_shared;
 	spa_t *spa = ztest_spa;
 	vdev_t *rvd = spa->spa_root_vdev;
@@ -3491,10 +3492,10 @@ ztest_vdev_aux_add_remove(ztest_ds_t *zd, uint64_t id)
 /*
  * split a pool if it has mirror tlvdevs
  */
-/* ARGSUSED */
 void
 ztest_split_pool(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	ztest_shared_t *zs = ztest_shared;
 	spa_t *spa = ztest_spa;
 	vdev_t *rvd = spa->spa_root_vdev;
@@ -3586,10 +3587,10 @@ ztest_split_pool(ztest_ds_t *zd, uint64_t id)
 /*
  * Verify that we can attach and detach devices.
  */
-/* ARGSUSED */
 void
 ztest_vdev_attach_detach(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	ztest_shared_t *zs = ztest_shared;
 	spa_t *spa = ztest_spa;
 	spa_aux_vdev_t *sav = &spa->spa_spares;
@@ -3829,10 +3830,10 @@ out:
 	umem_free(newpath, MAXPATHLEN);
 }
 
-/* ARGSUSED */
 void
 ztest_device_removal(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	spa_t *spa = ztest_spa;
 	vdev_t *vd;
 	uint64_t guid;
@@ -3922,10 +3923,10 @@ grow_vdev(vdev_t *vd, void *arg)
 /*
  * Callback function which expands a given vdev by calling vdev_online().
  */
-/* ARGSUSED */
 static vdev_t *
 online_vdev(vdev_t *vd, void *arg)
 {
+	(void) arg;
 	spa_t *spa = vd->vdev_spa;
 	vdev_t *tvd = vd->vdev_top;
 	uint64_t guid = vd->vdev_guid;
@@ -4006,10 +4007,10 @@ vdev_walk_tree(vdev_t *vd, vdev_t *(*func)(vdev_t *, void *), void *arg)
 /*
  * Verify that dynamic LUN growth works as expected.
  */
-/* ARGSUSED */
 void
 ztest_vdev_LUN_growth(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	spa_t *spa = ztest_spa;
 	vdev_t *vd, *tvd;
 	metaslab_class_t *mc;
@@ -4161,10 +4162,11 @@ ztest_vdev_LUN_growth(ztest_ds_t *zd, uint64_t id)
 /*
  * Verify that dmu_objset_{create,destroy,open,close} work as expected.
  */
-/* ARGSUSED */
 static void
 ztest_objset_create_cb(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx)
 {
+	(void) arg, (void) cr;
+
 	/*
 	 * Create the objects common to all ztest datasets.
 	 */
@@ -4241,10 +4243,10 @@ ztest_dataset_create(char *dsname)
 	    ZFS_SYNC_ALWAYS, B_FALSE));
 }
 
-/* ARGSUSED */
 static int
 ztest_objset_destroy_cb(const char *name, void *arg)
 {
+	(void) arg;
 	objset_t *os;
 	dmu_object_info_t doi;
 	int error;
@@ -4317,10 +4319,10 @@ ztest_snapshot_destroy(char *osname, uint64_t id)
 	return (B_TRUE);
 }
 
-/* ARGSUSED */
 void
 ztest_dmu_objset_create_destroy(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd;
 	ztest_ds_t *zdtmp;
 	int iters;
 	int error;
@@ -4642,6 +4644,7 @@ ztest_dmu_object_alloc_free(ztest_ds_t *zd, uint64_t id)
 void
 ztest_dmu_object_next_chunk(ztest_ds_t *zd, uint64_t id)
 {
+	(void) id;
 	objset_t *os = zd->zd_os;
 	int dnodes_per_chunk = 1 << dmu_object_alloc_chunk_shift;
 	uint64_t object;
@@ -5188,10 +5191,10 @@ ztest_dmu_read_write_zcopy(ztest_ds_t *zd, uint64_t id)
 	umem_free(od, size);
 }
 
-/* ARGSUSED */
 void
 ztest_dmu_write_parallel(ztest_ds_t *zd, uint64_t id)
 {
+	(void) id;
 	ztest_od_t *od;
 
 	od = umem_alloc(sizeof (ztest_od_t), UMEM_NOFAIL);
@@ -5450,10 +5453,10 @@ out:
 	umem_free(od, sizeof (ztest_od_t));
 }
 
-/* ARGSUSED */
 void
 ztest_zap_parallel(ztest_ds_t *zd, uint64_t id)
 {
+	(void) id;
 	objset_t *os = zd->zd_os;
 	ztest_od_t *od;
 	uint64_t txg, object, count, wsize, wc, zl_wsize, zl_wc;
@@ -5785,10 +5788,10 @@ ztest_dmu_commit_callbacks(ztest_ds_t *zd, uint64_t id)
  * are consistent what was stored in the block tag when it was created,
  * and that its unused bonus buffer space has not been overwritten.
  */
-/* ARGSUSED */
 void
 ztest_verify_dnode_bt(ztest_ds_t *zd, uint64_t id)
 {
+	(void) id;
 	objset_t *os = zd->zd_os;
 	uint64_t obj;
 	int err = 0;
@@ -5820,21 +5823,20 @@ ztest_verify_dnode_bt(ztest_ds_t *zd, uint64_t id)
 	}
 }
 
-/* ARGSUSED */
 void
 ztest_dsl_prop_get_set(ztest_ds_t *zd, uint64_t id)
 {
+	(void) id;
 	zfs_prop_t proplist[] = {
 		ZFS_PROP_CHECKSUM,
 		ZFS_PROP_COMPRESSION,
 		ZFS_PROP_COPIES,
 		ZFS_PROP_DEDUP
 	};
-	int p;
 
 	(void) pthread_rwlock_rdlock(&ztest_name_lock);
 
-	for (p = 0; p < sizeof (proplist) / sizeof (proplist[0]); p++)
+	for (int p = 0; p < sizeof (proplist) / sizeof (proplist[0]); p++)
 		(void) ztest_dsl_prop_set_uint64(zd->zd_name, proplist[p],
 		    ztest_random_dsl_prop(proplist[p]), (int)ztest_random(2));
 
@@ -5844,10 +5846,10 @@ ztest_dsl_prop_get_set(ztest_ds_t *zd, uint64_t id)
 	(void) pthread_rwlock_unlock(&ztest_name_lock);
 }
 
-/* ARGSUSED */
 void
 ztest_spa_prop_get_set(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	nvlist_t *props = NULL;
 
 	(void) pthread_rwlock_rdlock(&ztest_name_lock);
@@ -6008,10 +6010,10 @@ out:
 /*
  * Inject random faults into the on-disk data.
  */
-/* ARGSUSED */
 void
 ztest_fault_inject(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	ztest_shared_t *zs = ztest_shared;
 	spa_t *spa = ztest_spa;
 	int fd;
@@ -6324,10 +6326,10 @@ ztest_scrub_impl(spa_t *spa)
 /*
  * Scrub the pool.
  */
-/* ARGSUSED */
 void
 ztest_scrub(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	spa_t *spa = ztest_spa;
 	int error;
 
@@ -6352,10 +6354,10 @@ ztest_scrub(ztest_ds_t *zd, uint64_t id)
 /*
  * Change the guid for the pool.
  */
-/* ARGSUSED */
 void
 ztest_reguid(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	spa_t *spa = ztest_spa;
 	uint64_t orig, load;
 	int error;
@@ -6385,6 +6387,7 @@ ztest_reguid(ztest_ds_t *zd, uint64_t id)
 void
 ztest_fletcher(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	hrtime_t end = gethrtime() + NANOSEC;
 
 	while (gethrtime() <= end) {
@@ -6454,6 +6457,7 @@ ztest_fletcher(ztest_ds_t *zd, uint64_t id)
 void
 ztest_fletcher_incr(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	void *buf;
 	size_t size;
 	int *ptr;
@@ -6657,10 +6661,10 @@ ztest_random_concrete_vdev_leaf(vdev_t *vd)
 	return (ztest_random_concrete_vdev_leaf(eligible[child_no]));
 }
 
-/* ARGSUSED */
 void
 ztest_initialize(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	spa_t *spa = ztest_spa;
 	int error = 0;
 
@@ -6729,10 +6733,10 @@ ztest_initialize(ztest_ds_t *zd, uint64_t id)
 	mutex_exit(&ztest_vdev_lock);
 }
 
-/* ARGSUSED */
 void
 ztest_trim(ztest_ds_t *zd, uint64_t id)
 {
+	(void) zd, (void) id;
 	spa_t *spa = ztest_spa;
 	int error = 0;
 
@@ -7246,10 +7250,10 @@ ztest_dataset_close(int d)
 	ztest_zd_fini(zd);
 }
 
-/* ARGSUSED */
 static int
 ztest_replay_zil_cb(const char *name, void *arg)
 {
+	(void) arg;
 	objset_t *os;
 	ztest_ds_t *zdtmp;
 
@@ -7371,7 +7375,7 @@ ztest_freeze(void)
 }
 
 static void
-ztest_import_impl(ztest_shared_t *zs)
+ztest_import_impl(void)
 {
 	importargs_t args = { 0 };
 	nvlist_t *cfg = NULL;
@@ -7404,7 +7408,7 @@ ztest_import(ztest_shared_t *zs)
 
 	kernel_init(SPA_MODE_READ | SPA_MODE_WRITE);
 
-	ztest_import_impl(zs);
+	ztest_import_impl();
 
 	VERIFY0(spa_open(ztest_opts.zo_pool, &spa, FTAG));
 	zs->zs_metaslab_sz =
@@ -7470,7 +7474,7 @@ ztest_run(ztest_shared_t *zs)
 	error = spa_open(ztest_opts.zo_pool, &spa, FTAG);
 	if (error) {
 		VERIFY3S(error, ==, ENOENT);
-		ztest_import_impl(zs);
+		ztest_import_impl();
 		VERIFY0(spa_open(ztest_opts.zo_pool, &spa, FTAG));
 		zs->zs_metaslab_sz =
 		    1ULL << spa->spa_root_vdev->vdev_child[0]->vdev_ms_shift;