diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index 202b5a6197..a5fbdb2454 100644
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -734,13 +734,19 @@ dump_ddt(ddt_t *ddt, enum ddt_type type, enum ddt_class class)
 static void
 dump_all_ddts(spa_t *spa)
 {
-	ddt_histogram_t ddh_total = { 0 };
-	ddt_stat_t dds_total = { 0 };
+	ddt_histogram_t ddh_total;
+	ddt_stat_t dds_total;
+	enum zio_checksum c;
+	enum ddt_type type;
+	enum ddt_class class;
 
-	for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
+	bzero(&ddh_total, sizeof (ddt_histogram_t));
+	bzero(&dds_total, sizeof (ddt_stat_t));
+
+	for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 		ddt_t *ddt = spa->spa_ddt[c];
-		for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
-			for (enum ddt_class class = 0; class < DDT_CLASSES;
+		for (type = 0; type < DDT_TYPES; type++) {
+			for (class = 0; class < DDT_CLASSES;
 			    class++) {
 				dump_ddt(ddt, type, class);
 			}
diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index 9b643062af..ebce811d37 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -1432,10 +1432,11 @@ arc_buf_destroy(arc_buf_t *buf, boolean_t recycle, boolean_t all)
 static void
 arc_hdr_destroy(arc_buf_hdr_t *hdr)
 {
+	l2arc_buf_hdr_t *l2hdr = hdr->b_l2hdr;
+
 	ASSERT(refcount_is_zero(&hdr->b_refcnt));
 	ASSERT3P(hdr->b_state, ==, arc_anon);
 	ASSERT(!HDR_IO_IN_PROGRESS(hdr));
-	l2arc_buf_hdr_t *l2hdr = hdr->b_l2hdr;
 
 	if (l2hdr != NULL) {
 		boolean_t buflist_held = MUTEX_HELD(&l2arc_buflist_mtx);
diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c
index 22e7188bcf..5b19e750f9 100644
--- a/module/zfs/dbuf.c
+++ b/module/zfs/dbuf.c
@@ -107,9 +107,9 @@ dbuf_find(dnode_t *dn, uint8_t level, uint64_t blkid)
 {
 	dbuf_hash_table_t *h = &dbuf_hash_table;
 	objset_t *os = dn->dn_objset;
-	uint64_t obj = dn->dn_object;
-	uint64_t hv = DBUF_HASH(os, obj, level, blkid);
-	uint64_t idx = hv & h->hash_table_mask;
+	uint64_t obj;
+	uint64_t hv;
+	uint64_t idx;
 	dmu_buf_impl_t *db;
 
 	obj = dn->dn_object;
diff --git a/module/zfs/ddt.c b/module/zfs/ddt.c
index cd4e8476c2..7420173cc9 100644
--- a/module/zfs/ddt.c
+++ b/module/zfs/ddt.c
@@ -446,11 +446,15 @@ ddt_histogram_empty(const ddt_histogram_t *ddh)
 void
 ddt_get_dedup_object_stats(spa_t *spa, ddt_object_t *ddo_total)
 {
+	enum zio_checksum c;
+	enum ddt_type type;
+	enum ddt_class class;
+
 	/* Sum the statistics we cached in ddt_object_sync(). */
-	for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
+	for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 		ddt_t *ddt = spa->spa_ddt[c];
-		for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
-			for (enum ddt_class class = 0; class < DDT_CLASSES;
+		for (type = 0; type < DDT_TYPES; type++) {
+			for (class = 0; class < DDT_CLASSES;
 			    class++) {
 				ddt_object_t *ddo =
 				    &ddt->ddt_object_stats[type][class];
@@ -474,10 +478,14 @@ ddt_get_dedup_object_stats(spa_t *spa, ddt_object_t *ddo_total)
 void
 ddt_get_dedup_histogram(spa_t *spa, ddt_histogram_t *ddh)
 {
-	for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
+	enum zio_checksum c;
+	enum ddt_type type;
+	enum ddt_class class;
+
+	for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 		ddt_t *ddt = spa->spa_ddt[c];
-		for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
-			for (enum ddt_class class = 0; class < DDT_CLASSES;
+		for (type = 0; type < DDT_TYPES; type++) {
+			for (class = 0; class < DDT_CLASSES;
 			    class++) {
 				ddt_histogram_add(ddh,
 				    &ddt->ddt_histogram_cache[type][class]);
@@ -650,9 +658,10 @@ ddt_alloc(const ddt_key_t *ddk)
 static void
 ddt_free(ddt_entry_t *dde)
 {
-	ASSERT(!dde->dde_loading);
 	int p;
 
+	ASSERT(!dde->dde_loading);
+
 	for (p = 0; p < DDT_PHYS_TYPES; p++)
 		ASSERT(dde->dde_lead_zio[p] == NULL);
 
@@ -741,6 +750,8 @@ ddt_prefetch(spa_t *spa, const blkptr_t *bp)
 {
 	ddt_t *ddt;
 	ddt_entry_t dde;
+	enum ddt_type type;
+	enum ddt_class class;
 
 	if (!BP_GET_DEDUP(bp))
 		return;
@@ -753,8 +764,8 @@ ddt_prefetch(spa_t *spa, const blkptr_t *bp)
 	ddt = ddt_select(spa, bp);
 	ddt_key_fill(&dde.dde_key, bp);
 
-	for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
-		for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
+	for (type = 0; type < DDT_TYPES; type++) {
+		for (class = 0; class < DDT_CLASSES; class++) {
 			ddt_object_prefetch(ddt, type, class, &dde);
 		}
 	}
@@ -812,15 +823,20 @@ ddt_table_free(ddt_t *ddt)
 void
 ddt_create(spa_t *spa)
 {
+	enum zio_checksum c;
+
 	spa->spa_dedup_checksum = ZIO_DEDUPCHECKSUM;
 
-	for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++)
+	for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++)
 		spa->spa_ddt[c] = ddt_table_alloc(spa, c);
 }
 
 int
 ddt_load(spa_t *spa)
 {
+	enum zio_checksum c;
+	enum ddt_type type;
+	enum ddt_class class;
 	int error;
 
 	ddt_create(spa);
@@ -832,10 +848,10 @@ ddt_load(spa_t *spa)
 	if (error)
 		return (error == ENOENT ? 0 : error);
 
-	for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
+	for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 		ddt_t *ddt = spa->spa_ddt[c];
-		for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
-			for (enum ddt_class class = 0; class < DDT_CLASSES;
+		for (type = 0; type < DDT_TYPES; type++) {
+			for (class = 0; class < DDT_CLASSES;
 			    class++) {
 				error = ddt_object_load(ddt, type, class);
 				if (error != 0 && error != ENOENT)
@@ -856,7 +872,9 @@ ddt_load(spa_t *spa)
 void
 ddt_unload(spa_t *spa)
 {
-	for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
+	enum zio_checksum c;
+
+	for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 		if (spa->spa_ddt[c]) {
 			ddt_table_free(spa->spa_ddt[c]);
 			spa->spa_ddt[c] = NULL;
@@ -869,6 +887,8 @@ ddt_class_contains(spa_t *spa, enum ddt_class max_class, const blkptr_t *bp)
 {
 	ddt_t *ddt;
 	ddt_entry_t dde;
+	enum ddt_type type;
+	enum ddt_class class;
 
 	if (!BP_GET_DEDUP(bp))
 		return (B_FALSE);
@@ -880,8 +900,8 @@ ddt_class_contains(spa_t *spa, enum ddt_class max_class, const blkptr_t *bp)
 
 	ddt_key_fill(&dde.dde_key, bp);
 
-	for (enum ddt_type type = 0; type < DDT_TYPES; type++)
-		for (enum ddt_class class = 0; class <= max_class; class++)
+	for (type = 0; type < DDT_TYPES; type++)
+		for (class = 0; class <= max_class; class++)
 			if (ddt_object_lookup(ddt, type, class, &dde) == 0)
 				return (B_TRUE);
 
@@ -893,13 +913,15 @@ ddt_repair_start(ddt_t *ddt, const blkptr_t *bp)
 {
 	ddt_key_t ddk;
 	ddt_entry_t *dde;
+	enum ddt_type type;
+	enum ddt_class class;
 
 	ddt_key_fill(&ddk, bp);
 
 	dde = ddt_alloc(&ddk);
 
-	for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
-		for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
+	for (type = 0; type < DDT_TYPES; type++) {
+		for (class = 0; class < DDT_CLASSES; class++) {
 			/*
 			 * We can only do repair if there are multiple copies
 			 * of the block.  For anything in the UNIQUE class,
@@ -1067,6 +1089,8 @@ ddt_sync_table(ddt_t *ddt, dmu_tx_t *tx, uint64_t txg)
 	spa_t *spa = ddt->ddt_spa;
 	ddt_entry_t *dde;
 	void *cookie = NULL;
+	enum ddt_type type;
+	enum ddt_class class;
 
 	if (avl_numnodes(&ddt->ddt_tree) == 0)
 		return;
@@ -1086,8 +1110,8 @@ ddt_sync_table(ddt_t *ddt, dmu_tx_t *tx, uint64_t txg)
 		ddt_free(dde);
 	}
 
-	for (enum ddt_type type = 0; type < DDT_TYPES; type++) {
-		for (enum ddt_class class = 0; class < DDT_CLASSES; class++) {
+	for (type = 0; type < DDT_TYPES; type++) {
+		for (class = 0; class < DDT_CLASSES; class++) {
 			if (!ddt_object_exists(ddt, type, class))
 				continue;
 			ddt_object_sync(ddt, type, class, tx);
@@ -1106,12 +1130,13 @@ ddt_sync(spa_t *spa, uint64_t txg)
 	dmu_tx_t *tx;
 	zio_t *rio = zio_root(spa, NULL, NULL,
 	    ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE);
+	enum zio_checksum c;
 
 	ASSERT(spa_syncing_txg(spa) == txg);
 
 	tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
 
-	for (enum zio_checksum c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
+	for (c = 0; c < ZIO_CHECKSUM_FUNCTIONS; c++) {
 		ddt_t *ddt = spa->spa_ddt[c];
 		if (ddt == NULL)
 			continue;
diff --git a/module/zfs/dsl_dataset.c b/module/zfs/dsl_dataset.c
index 2e1fff35a9..6a86bbca8a 100644
--- a/module/zfs/dsl_dataset.c
+++ b/module/zfs/dsl_dataset.c
@@ -92,7 +92,7 @@ dsl_dataset_block_born(dsl_dataset_t *ds, const blkptr_t *bp, dmu_tx_t *tx)
 	int used, compressed, uncompressed;
 	int64_t delta;
 
-	used = bp_get_dasize(tx->tx_pool->dp_spa, bp);
+	used = bp_get_dsize_sync(tx->tx_pool->dp_spa, bp);
 	compressed = BP_GET_PSIZE(bp);
 	uncompressed = BP_GET_UCSIZE(bp);
 
@@ -136,15 +136,17 @@ int
 dsl_dataset_block_kill(dsl_dataset_t *ds, const blkptr_t *bp, dmu_tx_t *tx,
     boolean_t async)
 {
+	int used, compressed, uncompressed;
+
 	if (BP_IS_HOLE(bp))
 		return (0);
 
 	ASSERT(dmu_tx_is_syncing(tx));
 	ASSERT(bp->blk_birth <= tx->tx_txg);
 
-	int used = bp_get_dsize_sync(tx->tx_pool->dp_spa, bp);
-	int compressed = BP_GET_PSIZE(bp);
-	int uncompressed = BP_GET_UCSIZE(bp);
+	used = bp_get_dsize_sync(tx->tx_pool->dp_spa, bp);
+	compressed = BP_GET_PSIZE(bp);
+	uncompressed = BP_GET_UCSIZE(bp);
 
 	ASSERT(used > 0);
 	if (ds == NULL) {
@@ -1753,6 +1755,7 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, dmu_tx_t *tx)
 
 		if (dsl_dataset_is_snapshot(ds_next)) {
 			dsl_dataset_t *ds_nextnext;
+			dsl_dataset_t *hds;
 
 			/*
 			 * Update next's unique to include blocks which
@@ -1775,7 +1778,6 @@ dsl_dataset_destroy_sync(void *arg1, void *tag, dmu_tx_t *tx)
 			ASSERT3P(ds_next->ds_prev, ==, NULL);
 
 			/* Collapse range in this head. */
-			dsl_dataset_t *hds;
 			VERIFY3U(0, ==, dsl_dataset_hold_obj(dp,
 			    ds->ds_dir->dd_phys->dd_head_dataset_obj,
 			    FTAG, &hds));
diff --git a/module/zfs/dsl_pool.c b/module/zfs/dsl_pool.c
index 2cd21a102b..b50c1518cd 100644
--- a/module/zfs/dsl_pool.c
+++ b/module/zfs/dsl_pool.c
@@ -692,9 +692,10 @@ upgrade_dir_clones_cb(spa_t *spa, uint64_t dsobj, const char *dsname, void *arg)
 void
 dsl_pool_upgrade_dir_clones(dsl_pool_t *dp, dmu_tx_t *tx)
 {
-	ASSERT(dmu_tx_is_syncing(tx));
 	uint64_t obj;
 
+	ASSERT(dmu_tx_is_syncing(tx));
+
 	(void) dsl_dir_create_sync(dp, dp->dp_root_dir, FREE_DIR_NAME, tx);
 	VERIFY(0 == dsl_pool_open_special_dir(dp,
 	    FREE_DIR_NAME, &dp->dp_free_dir));
diff --git a/module/zfs/dsl_scan.c b/module/zfs/dsl_scan.c
index e402dde7c3..0756f57f37 100644
--- a/module/zfs/dsl_scan.c
+++ b/module/zfs/dsl_scan.c
@@ -1072,6 +1072,7 @@ dsl_scan_visitds(dsl_scan_t *scn, uint64_t dsobj, dmu_tx_t *tx)
 {
 	dsl_pool_t *dp = scn->scn_dp;
 	dsl_dataset_t *ds;
+	char *dsname;
 
 	VERIFY3U(0, ==, dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
 
@@ -1081,7 +1082,7 @@ dsl_scan_visitds(dsl_scan_t *scn, uint64_t dsobj, dmu_tx_t *tx)
 	dmu_buf_will_dirty(ds->ds_dbuf, tx);
 	dsl_scan_visit_rootbp(scn, ds, &ds->ds_phys->ds_bp, tx);
 
-	char *dsname = kmem_alloc(ZFS_MAXNAMELEN, KM_SLEEP);
+	dsname = kmem_alloc(ZFS_MAXNAMELEN, KM_SLEEP);
 	dsl_dataset_name(ds, dsname);
 	zfs_dbgmsg("scanned dataset %llu (%s) with min=%llu max=%llu; "
 	    "pausing=%u",
diff --git a/module/zfs/sa.c b/module/zfs/sa.c
index a91b379f99..0ce2b9cd5c 100644
--- a/module/zfs/sa.c
+++ b/module/zfs/sa.c
@@ -1402,8 +1402,8 @@ sa_find_idx_tab(objset_t *os, dmu_object_type_t bonustype, void *data)
 
 	/* Verify header size is consistent with layout information */
 	ASSERT(tb);
-	ASSERT(IS_SA_BONUSTYPE(bonustype) &&
-	    SA_HDR_SIZE_MATCH_LAYOUT(hdr, tb) || !IS_SA_BONUSTYPE(bonustype) ||
+	ASSERT((IS_SA_BONUSTYPE(bonustype) &&
+	    SA_HDR_SIZE_MATCH_LAYOUT(hdr, tb)) || !IS_SA_BONUSTYPE(bonustype) ||
 	    (IS_SA_BONUSTYPE(bonustype) && hdr->sa_layout_info == 0));
 
 	/*
diff --git a/module/zfs/spa.c b/module/zfs/spa.c
index b0236e49f9..c90607a089 100644
--- a/module/zfs/spa.c
+++ b/module/zfs/spa.c
@@ -1677,7 +1677,6 @@ spa_load_impl(spa_t *spa, uint64_t pool_guid, nvlist_t *config,
 	int orig_mode = spa->spa_mode;
 	int parse;
 	uint64_t obj;
-	int c;
 
 	/*
 	 * If this is an untrusted config, access the pool in read-only mode.
@@ -2707,6 +2706,7 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
 	nvlist_t **spares, **l2cache;
 	uint_t nspares, nl2cache;
 	uint64_t version, obj;
+	int c;
 
 	/*
 	 * If this pool already exists, return failure.
diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c
index 20946c4e75..2726d6994f 100644
--- a/module/zfs/spa_misc.c
+++ b/module/zfs/spa_misc.c
@@ -884,10 +884,9 @@ spa_vdev_config_enter(spa_t *spa)
 void
 spa_vdev_config_exit(spa_t *spa, vdev_t *vd, uint64_t txg, int error, char *tag)
 {
-	ASSERT(MUTEX_HELD(&spa_namespace_lock));
-
 	int config_changed = B_FALSE;
 
+	ASSERT(MUTEX_HELD(&spa_namespace_lock));
 	ASSERT(txg > spa_last_synced_txg(spa));
 
 	spa->spa_pending_vdev = NULL;
diff --git a/module/zfs/vdev_label.c b/module/zfs/vdev_label.c
index 023a36b7aa..cc6343cfd1 100644
--- a/module/zfs/vdev_label.c
+++ b/module/zfs/vdev_label.c
@@ -1075,12 +1075,13 @@ vdev_label_sync_list(spa_t *spa, int l, uint64_t txg, int flags)
 	zio = zio_root(spa, NULL, NULL, flags);
 
 	for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd)) {
-		uint64_t *good_writes = kmem_zalloc(sizeof (uint64_t),
-		    KM_SLEEP);
+		uint64_t *good_writes;
+		zio_t *vio;
 
 		ASSERT(!vd->vdev_ishole);
 
-		zio_t *vio = zio_null(zio, spa, NULL,
+		good_writes = kmem_zalloc(sizeof (uint64_t), KM_SLEEP);
+		vio = zio_null(zio, spa, NULL,
 		    (vd->vdev_islog || vd->vdev_aux != NULL) ?
 		    vdev_label_sync_ignore_done : vdev_label_sync_top_done,
 		    good_writes, flags);
diff --git a/module/zfs/zfs_znode.c b/module/zfs/zfs_znode.c
index 24bd3ddcdd..17fdb9b7af 100644
--- a/module/zfs/zfs_znode.c
+++ b/module/zfs/zfs_znode.c
@@ -1892,8 +1892,8 @@ zfs_obj_to_pobj(objset_t *osp, uint64_t obj, uint64_t *pobjp, int *is_xattrdir,
 	dmu_object_info_from_db(db, &doi);
 	if ((doi.doi_bonus_type != DMU_OT_SA &&
 	    doi.doi_bonus_type != DMU_OT_ZNODE) ||
-	    doi.doi_bonus_type == DMU_OT_ZNODE &&
-	    doi.doi_bonus_size < sizeof (znode_phys_t)) {
+	    (doi.doi_bonus_type == DMU_OT_ZNODE &&
+	    doi.doi_bonus_size < sizeof (znode_phys_t))) {
 		sa_buf_rele(db, FTAG);
 		return (EINVAL);
 	}
diff --git a/module/zfs/zio.c b/module/zfs/zio.c
index 520639e063..c70786c42b 100644
--- a/module/zfs/zio.c
+++ b/module/zfs/zio.c
@@ -2171,6 +2171,8 @@ zio_dva_claim(zio_t *zio)
 static void
 zio_dva_unallocate(zio_t *zio, zio_gang_node_t *gn, blkptr_t *bp)
 {
+	int g;
+
 	ASSERT(bp->blk_birth == zio->io_txg || BP_IS_HOLE(bp));
 	ASSERT(zio->io_bp_override == NULL);