diff --git a/include/libzfs.h b/include/libzfs.h
index d9f0d7259..64a0a2035 100644
--- a/include/libzfs.h
+++ b/include/libzfs.h
@@ -313,7 +313,7 @@ extern nvlist_t *zpool_find_vdev(zpool_handle_t *, const char *, boolean_t *,
     boolean_t *, boolean_t *);
 extern nvlist_t *zpool_find_vdev_by_physpath(zpool_handle_t *, const char *,
     boolean_t *, boolean_t *, boolean_t *);
-extern int zpool_label_disk(libzfs_handle_t *, zpool_handle_t *, char *);
+extern int zpool_label_disk(libzfs_handle_t *, zpool_handle_t *, const char *);
 extern uint64_t zpool_vdev_path_to_guid(zpool_handle_t *zhp, const char *path);
 
 const char *zpool_get_state_str(zpool_handle_t *);
diff --git a/include/os/freebsd/spl/sys/ccompile.h b/include/os/freebsd/spl/sys/ccompile.h
index 0bb0e637c..f9b09d430 100644
--- a/include/os/freebsd/spl/sys/ccompile.h
+++ b/include/os/freebsd/spl/sys/ccompile.h
@@ -294,7 +294,9 @@ typedef long loff_t;
 typedef long rlim64_t;
 typedef int bool_t;
 typedef int enum_t;
+#ifndef __cplusplus
 #define	__init
+#endif
 #define	__exit
 #define	FALSE 0
 #define	TRUE 1
diff --git a/include/sys/abd.h b/include/sys/abd.h
index be37b4a81..3b490005c 100644
--- a/include/sys/abd.h
+++ b/include/sys/abd.h
@@ -38,8 +38,8 @@ extern "C" {
 struct abd; /* forward declaration */
 typedef struct abd abd_t;
 
-typedef int abd_iter_func_t(void *buf, size_t len, void *private);
-typedef int abd_iter_func2_t(void *bufa, void *bufb, size_t len, void *private);
+typedef int abd_iter_func_t(void *buf, size_t len, void *priv);
+typedef int abd_iter_func2_t(void *bufa, void *bufb, size_t len, void *priv);
 
 extern int zfs_abd_scatter_enabled;
 extern abd_t *abd_zero_scatter;
diff --git a/include/sys/arc.h b/include/sys/arc.h
index f500e1d45..f358bc9ae 100644
--- a/include/sys/arc.h
+++ b/include/sys/arc.h
@@ -70,9 +70,9 @@ typedef struct arc_prune arc_prune_t;
  * parameter will be NULL.
  */
 typedef void arc_read_done_func_t(zio_t *zio, const zbookmark_phys_t *zb,
-    const blkptr_t *bp, arc_buf_t *buf, void *private);
-typedef void arc_write_done_func_t(zio_t *zio, arc_buf_t *buf, void *private);
-typedef void arc_prune_func_t(int64_t bytes, void *private);
+    const blkptr_t *bp, arc_buf_t *buf, void *priv);
+typedef void arc_write_done_func_t(zio_t *zio, arc_buf_t *buf, void *priv);
+typedef void arc_prune_func_t(int64_t bytes, void *priv);
 
 /* Shared module parameters */
 extern int zfs_arc_average_blocksize;
@@ -280,16 +280,16 @@ int arc_referenced(arc_buf_t *buf);
 #endif
 
 int arc_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
-    arc_read_done_func_t *done, void *private, zio_priority_t priority,
+    arc_read_done_func_t *done, void *priv, zio_priority_t priority,
     int flags, arc_flags_t *arc_flags, const zbookmark_phys_t *zb);
 zio_t *arc_write(zio_t *pio, spa_t *spa, uint64_t txg,
     blkptr_t *bp, arc_buf_t *buf, boolean_t l2arc, const zio_prop_t *zp,
     arc_write_done_func_t *ready, arc_write_done_func_t *child_ready,
     arc_write_done_func_t *physdone, arc_write_done_func_t *done,
-    void *private, zio_priority_t priority, int zio_flags,
+    void *priv, zio_priority_t priority, int zio_flags,
     const zbookmark_phys_t *zb);
 
-arc_prune_t *arc_add_prune_callback(arc_prune_func_t *func, void *private);
+arc_prune_t *arc_add_prune_callback(arc_prune_func_t *func, void *priv);
 void arc_remove_prune_callback(arc_prune_t *p);
 void arc_freed(spa_t *spa, const blkptr_t *bp);
 
diff --git a/include/sys/ddt.h b/include/sys/ddt.h
index 21b76f7ba..0d7c4f927 100644
--- a/include/sys/ddt.h
+++ b/include/sys/ddt.h
@@ -182,15 +182,15 @@ typedef struct ddt_ops {
 #define	DDT_NAMELEN	80
 
 extern void ddt_object_name(ddt_t *ddt, enum ddt_type type,
-    enum ddt_class class, char *name);
+    enum ddt_class clazz, char *name);
 extern int ddt_object_walk(ddt_t *ddt, enum ddt_type type,
-    enum ddt_class class, uint64_t *walk, ddt_entry_t *dde);
+    enum ddt_class clazz, uint64_t *walk, ddt_entry_t *dde);
 extern int ddt_object_count(ddt_t *ddt, enum ddt_type type,
-    enum ddt_class class, uint64_t *count);
+    enum ddt_class clazz, uint64_t *count);
 extern int ddt_object_info(ddt_t *ddt, enum ddt_type type,
-    enum ddt_class class, dmu_object_info_t *);
+    enum ddt_class clazz, dmu_object_info_t *);
 extern boolean_t ddt_object_exists(ddt_t *ddt, enum ddt_type type,
-    enum ddt_class class);
+    enum ddt_class clazz);
 
 extern void ddt_bp_fill(const ddt_phys_t *ddp, blkptr_t *bp,
     uint64_t txg);
@@ -246,7 +246,7 @@ extern void ddt_unload(spa_t *spa);
 extern void ddt_sync(spa_t *spa, uint64_t txg);
 extern int ddt_walk(spa_t *spa, ddt_bookmark_t *ddb, ddt_entry_t *dde);
 extern int ddt_object_update(ddt_t *ddt, enum ddt_type type,
-    enum ddt_class class, ddt_entry_t *dde, dmu_tx_t *tx);
+    enum ddt_class clazz, ddt_entry_t *dde, dmu_tx_t *tx);
 
 extern const ddt_ops_t ddt_zap_ops;
 
diff --git a/include/sys/dsl_dataset.h b/include/sys/dsl_dataset.h
index 9db39d5f8..9de9a88d8 100644
--- a/include/sys/dsl_dataset.h
+++ b/include/sys/dsl_dataset.h
@@ -273,7 +273,7 @@ typedef struct dsl_dataset {
 static inline dsl_dataset_phys_t *
 dsl_dataset_phys(dsl_dataset_t *ds)
 {
-	return (ds->ds_dbuf->db_data);
+	return ((dsl_dataset_phys_t *)ds->ds_dbuf->db_data);
 }
 
 typedef struct dsl_dataset_promote_arg {
@@ -417,10 +417,10 @@ void dsl_dataset_space(dsl_dataset_t *ds,
     uint64_t *refdbytesp, uint64_t *availbytesp,
     uint64_t *usedobjsp, uint64_t *availobjsp);
 uint64_t dsl_dataset_fsid_guid(dsl_dataset_t *ds);
-int dsl_dataset_space_written(dsl_dataset_t *oldsnap, dsl_dataset_t *new,
+int dsl_dataset_space_written(dsl_dataset_t *oldsnap, dsl_dataset_t *newds,
     uint64_t *usedp, uint64_t *compp, uint64_t *uncompp);
 int dsl_dataset_space_written_bookmark(struct zfs_bookmark_phys *bmp,
-    dsl_dataset_t *new, uint64_t *usedp, uint64_t *compp, uint64_t *uncompp);
+    dsl_dataset_t *newds, uint64_t *usedp, uint64_t *compp, uint64_t *uncompp);
 int dsl_dataset_space_wouldfree(dsl_dataset_t *firstsnap, dsl_dataset_t *last,
     uint64_t *usedp, uint64_t *compp, uint64_t *uncompp);
 
diff --git a/include/sys/range_tree.h b/include/sys/range_tree.h
index b0a9a1dad..fef3d4d7b 100644
--- a/include/sys/range_tree.h
+++ b/include/sys/range_tree.h
@@ -160,11 +160,11 @@ rs_get_fill_raw(const range_seg_t *rs, const range_tree_t *rt)
 	ASSERT3U(rt->rt_type, <=, RANGE_SEG_NUM_TYPES);
 	switch (rt->rt_type) {
 	case RANGE_SEG32: {
-		const range_seg32_t *r32 = rs;
+		const range_seg32_t *r32 = (const range_seg32_t *)rs;
 		return (r32->rs_end - r32->rs_start);
 	}
 	case RANGE_SEG64: {
-		const range_seg64_t *r64 = rs;
+		const range_seg64_t *r64 = (const range_seg64_t *)rs;
 		return (r64->rs_end - r64->rs_start);
 	}
 	case RANGE_SEG_GAP:
diff --git a/include/sys/spa.h b/include/sys/spa.h
index 6e844f5ee..a03319e2b 100644
--- a/include/sys/spa.h
+++ b/include/sys/spa.h
@@ -891,7 +891,7 @@ typedef struct spa_history_kstat {
 	uint64_t		count;
 	uint64_t		size;
 	kstat_t			*kstat;
-	void			*private;
+	void			*priv;
 	list_t			list;
 } spa_history_kstat_t;
 
@@ -1131,10 +1131,10 @@ extern const char *spa_state_to_name(spa_t *spa);
 /* error handling */
 struct zbookmark_phys;
 extern void spa_log_error(spa_t *spa, const zbookmark_phys_t *zb);
-extern int zfs_ereport_post(const char *class, spa_t *spa, vdev_t *vd,
+extern int zfs_ereport_post(const char *clazz, spa_t *spa, vdev_t *vd,
     const zbookmark_phys_t *zb, zio_t *zio, uint64_t stateoroffset,
     uint64_t length);
-extern boolean_t zfs_ereport_is_valid(const char *class, spa_t *spa, vdev_t *vd,
+extern boolean_t zfs_ereport_is_valid(const char *clazz, spa_t *spa, vdev_t *vd,
     zio_t *zio);
 extern nvlist_t *zfs_event_create(spa_t *spa, vdev_t *vd, const char *type,
     const char *name, nvlist_t *aux);
diff --git a/include/sys/vdev.h b/include/sys/vdev.h
index c4ef479b5..d93ef78f1 100644
--- a/include/sys/vdev.h
+++ b/include/sys/vdev.h
@@ -178,7 +178,7 @@ extern nvlist_t *vdev_label_read_config(vdev_t *vd, uint64_t txg);
 extern void vdev_uberblock_load(vdev_t *, struct uberblock *, nvlist_t **);
 extern void vdev_config_generate_stats(vdev_t *vd, nvlist_t *nv);
 extern void vdev_label_write(zio_t *zio, vdev_t *vd, int l, abd_t *buf, uint64_t
-    offset, uint64_t size, zio_done_func_t *done, void *private, int flags);
+    offset, uint64_t size, zio_done_func_t *done, void *priv, int flags);
 extern int vdev_label_read_bootenv(vdev_t *, nvlist_t *);
 extern int vdev_label_write_bootenv(vdev_t *, char *);
 
diff --git a/include/sys/zfs_context.h b/include/sys/zfs_context.h
index 00642175d..72fcd74ca 100644
--- a/include/sys/zfs_context.h
+++ b/include/sys/zfs_context.h
@@ -28,6 +28,10 @@
 #ifndef _SYS_ZFS_CONTEXT_H
 #define	_SYS_ZFS_CONTEXT_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #ifdef __KERNEL__
 #include <sys/note.h>
 #include <sys/types.h>
@@ -355,9 +359,6 @@ extern void kstat_set_raw_ops(kstat_t *ksp,
  * procfs list manipulation
  */
 
-struct seq_file { };
-void seq_printf(struct seq_file *m, const char *fmt, ...);
-
 typedef struct procfs_list {
 	void		*pl_private;
 	kmutex_t	pl_lock;
@@ -366,6 +367,10 @@ typedef struct procfs_list {
 	size_t		pl_node_offset;
 } procfs_list_t;
 
+#ifndef __cplusplus
+struct seq_file { };
+void seq_printf(struct seq_file *m, const char *fmt, ...);
+
 typedef struct procfs_list_node {
 	list_node_t	pln_link;
 	uint64_t	pln_id;
@@ -382,6 +387,7 @@ void procfs_list_install(const char *module,
 void procfs_list_uninstall(procfs_list_t *procfs_list);
 void procfs_list_destroy(procfs_list_t *procfs_list);
 void procfs_list_add(procfs_list_t *procfs_list, void *p);
+#endif
 
 /*
  * Kernel memory
@@ -742,4 +748,9 @@ extern int kmem_cache_reap_active(void);
 #define	____cacheline_aligned
 
 #endif /* _KERNEL */
+
+#ifdef __cplusplus
+};
+#endif
+
 #endif	/* _SYS_ZFS_CONTEXT_H */
diff --git a/include/sys/zio.h b/include/sys/zio.h
index 368d8c149..dc4942a5d 100644
--- a/include/sys/zio.h
+++ b/include/sys/zio.h
@@ -525,24 +525,24 @@ enum blk_verify_flag {
 extern int zio_bookmark_compare(const void *, const void *);
 
 extern zio_t *zio_null(zio_t *pio, spa_t *spa, vdev_t *vd,
-    zio_done_func_t *done, void *private, enum zio_flag flags);
+    zio_done_func_t *done, void *priv, enum zio_flag flags);
 
 extern zio_t *zio_root(spa_t *spa,
-    zio_done_func_t *done, void *private, enum zio_flag flags);
+    zio_done_func_t *done, void *priv, enum zio_flag flags);
 
 extern zio_t *zio_read(zio_t *pio, spa_t *spa, const blkptr_t *bp,
-    struct abd *data, uint64_t lsize, zio_done_func_t *done, void *private,
+    struct abd *data, uint64_t lsize, zio_done_func_t *done, void *priv,
     zio_priority_t priority, enum zio_flag flags, const zbookmark_phys_t *zb);
 
 extern zio_t *zio_write(zio_t *pio, spa_t *spa, uint64_t txg, blkptr_t *bp,
     struct abd *data, uint64_t size, uint64_t psize, const zio_prop_t *zp,
     zio_done_func_t *ready, zio_done_func_t *children_ready,
     zio_done_func_t *physdone, zio_done_func_t *done,
-    void *private, zio_priority_t priority, enum zio_flag flags,
+    void *priv, zio_priority_t priority, enum zio_flag flags,
     const zbookmark_phys_t *zb);
 
 extern zio_t *zio_rewrite(zio_t *pio, spa_t *spa, uint64_t txg, blkptr_t *bp,
-    struct abd *data, uint64_t size, zio_done_func_t *done, void *private,
+    struct abd *data, uint64_t size, zio_done_func_t *done, void *priv,
     zio_priority_t priority, enum zio_flag flags, zbookmark_phys_t *zb);
 
 extern void zio_write_override(zio_t *zio, blkptr_t *bp, int copies,
@@ -552,23 +552,23 @@ extern void zio_free(spa_t *spa, uint64_t txg, const blkptr_t *bp);
 
 extern zio_t *zio_claim(zio_t *pio, spa_t *spa, uint64_t txg,
     const blkptr_t *bp,
-    zio_done_func_t *done, void *private, enum zio_flag flags);
+    zio_done_func_t *done, void *priv, enum zio_flag flags);
 
 extern zio_t *zio_ioctl(zio_t *pio, spa_t *spa, vdev_t *vd, int cmd,
-    zio_done_func_t *done, void *private, enum zio_flag flags);
+    zio_done_func_t *done, void *priv, enum zio_flag flags);
 
 extern zio_t *zio_trim(zio_t *pio, vdev_t *vd, uint64_t offset, uint64_t size,
-    zio_done_func_t *done, void *private, zio_priority_t priority,
+    zio_done_func_t *done, void *priv, zio_priority_t priority,
     enum zio_flag flags, enum trim_flag trim_flags);
 
 extern zio_t *zio_read_phys(zio_t *pio, vdev_t *vd, uint64_t offset,
     uint64_t size, struct abd *data, int checksum,
-    zio_done_func_t *done, void *private, zio_priority_t priority,
+    zio_done_func_t *done, void *priv, zio_priority_t priority,
     enum zio_flag flags, boolean_t labels);
 
 extern zio_t *zio_write_phys(zio_t *pio, vdev_t *vd, uint64_t offset,
     uint64_t size, struct abd *data, int checksum,
-    zio_done_func_t *done, void *private, zio_priority_t priority,
+    zio_done_func_t *done, void *priv, zio_priority_t priority,
     enum zio_flag flags, boolean_t labels);
 
 extern zio_t *zio_free_sync(zio_t *pio, spa_t *spa, uint64_t txg,
@@ -606,11 +606,11 @@ extern void zio_resubmit_stage_async(void *);
 extern zio_t *zio_vdev_child_io(zio_t *zio, blkptr_t *bp, vdev_t *vd,
     uint64_t offset, struct abd *data, uint64_t size, int type,
     zio_priority_t priority, enum zio_flag flags,
-    zio_done_func_t *done, void *private);
+    zio_done_func_t *done, void *priv);
 
 extern zio_t *zio_vdev_delegated_io(vdev_t *vd, uint64_t offset,
     struct abd *data, uint64_t size, zio_type_t type, zio_priority_t priority,
-    enum zio_flag flags, zio_done_func_t *done, void *private);
+    enum zio_flag flags, zio_done_func_t *done, void *priv);
 
 extern void zio_vdev_io_bypass(zio_t *zio);
 extern void zio_vdev_io_reissue(zio_t *zio);
diff --git a/lib/libspl/include/assert.h b/lib/libspl/include/assert.h
index 1b8f6befb..6f80f1334 100644
--- a/lib/libspl/include/assert.h
+++ b/lib/libspl/include/assert.h
@@ -50,7 +50,8 @@ libspl_assert(const char *buf, const char *file, const char *func, int line)
 
 /* printf version of libspl_assert */
 static inline void
-libspl_assertf(const char *file, const char *func, int line, char *format, ...)
+libspl_assertf(const char *file, const char *func, int line,
+    const char *format, ...)
 {
 	va_list args;
 
diff --git a/lib/libspl/include/umem.h b/lib/libspl/include/umem.h
index 59dc93144..a92dce9b2 100644
--- a/lib/libspl/include/umem.h
+++ b/lib/libspl/include/umem.h
@@ -145,7 +145,7 @@ umem_cache_create(
 {
 	umem_cache_t *cp;
 
-	cp = umem_alloc(sizeof (umem_cache_t), UMEM_DEFAULT);
+	cp = (umem_cache_t *)umem_alloc(sizeof (umem_cache_t), UMEM_DEFAULT);
 	if (cp) {
 		strlcpy(cp->cache_name, name, UMEM_CACHE_NAMELEN);
 		cp->cache_bufsize = bufsize;
diff --git a/lib/libzfs/os/freebsd/libzfs_compat.c b/lib/libzfs/os/freebsd/libzfs_compat.c
index e1c6ef93d..3cb844ddb 100644
--- a/lib/libzfs/os/freebsd/libzfs_compat.c
+++ b/lib/libzfs/os/freebsd/libzfs_compat.c
@@ -247,7 +247,7 @@ zpool_relabel_disk(libzfs_handle_t *hdl, const char *path, const char *msg)
 }
 
 int
-zpool_label_disk(libzfs_handle_t *hdl, zpool_handle_t *zhp, char *name)
+zpool_label_disk(libzfs_handle_t *hdl, zpool_handle_t *zhp, const char *name)
 {
 	return (0);
 }
diff --git a/lib/libzfs/os/linux/libzfs_pool_os.c b/lib/libzfs/os/linux/libzfs_pool_os.c
index e1250f121..5c6da5338 100644
--- a/lib/libzfs/os/linux/libzfs_pool_os.c
+++ b/lib/libzfs/os/linux/libzfs_pool_os.c
@@ -212,7 +212,7 @@ zpool_label_name(char *label_name, int label_size)
  * stripped of any leading /dev path.
  */
 int
-zpool_label_disk(libzfs_handle_t *hdl, zpool_handle_t *zhp, char *name)
+zpool_label_disk(libzfs_handle_t *hdl, zpool_handle_t *zhp, const char *name)
 {
 	char path[MAXPATHLEN];
 	struct dk_gpt *vtoc;
diff --git a/module/os/linux/zfs/spa_stats.c b/module/os/linux/zfs/spa_stats.c
index 0d7f540d1..eae9c3f22 100644
--- a/module/os/linux/zfs/spa_stats.c
+++ b/module/os/linux/zfs/spa_stats.c
@@ -478,11 +478,11 @@ spa_tx_assign_update(kstat_t *ksp, int rw)
 
 	if (rw == KSTAT_WRITE) {
 		for (i = 0; i < shk->count; i++)
-			((kstat_named_t *)shk->private)[i].value.ui64 = 0;
+			((kstat_named_t *)shk->priv)[i].value.ui64 = 0;
 	}
 
 	for (i = shk->count; i > 0; i--)
-		if (((kstat_named_t *)shk->private)[i-1].value.ui64 != 0)
+		if (((kstat_named_t *)shk->priv)[i-1].value.ui64 != 0)
 			break;
 
 	ksp->ks_ndata = i;
@@ -504,12 +504,12 @@ spa_tx_assign_init(spa_t *spa)
 
 	shk->count = 42; /* power of two buckets for 1ns to 2,199s */
 	shk->size = shk->count * sizeof (kstat_named_t);
-	shk->private = kmem_alloc(shk->size, KM_SLEEP);
+	shk->priv = kmem_alloc(shk->size, KM_SLEEP);
 
 	name = kmem_asprintf("zfs/%s", spa_name(spa));
 
 	for (i = 0; i < shk->count; i++) {
-		ks = &((kstat_named_t *)shk->private)[i];
+		ks = &((kstat_named_t *)shk->priv)[i];
 		ks->data_type = KSTAT_DATA_UINT64;
 		ks->value.ui64 = 0;
 		(void) snprintf(ks->name, KSTAT_STRLEN, "%llu ns",
@@ -522,7 +522,7 @@ spa_tx_assign_init(spa_t *spa)
 
 	if (ksp) {
 		ksp->ks_lock = &shk->lock;
-		ksp->ks_data = shk->private;
+		ksp->ks_data = shk->priv;
 		ksp->ks_ndata = shk->count;
 		ksp->ks_data_size = shk->size;
 		ksp->ks_private = spa;
@@ -542,7 +542,7 @@ spa_tx_assign_destroy(spa_t *spa)
 	if (ksp)
 		kstat_delete(ksp);
 
-	kmem_free(shk->private, shk->size);
+	kmem_free(shk->priv, shk->size);
 	mutex_destroy(&shk->lock);
 }
 
@@ -555,7 +555,7 @@ spa_tx_assign_add_nsecs(spa_t *spa, uint64_t nsecs)
 	while (((1ULL << idx) < nsecs) && (idx < shk->size - 1))
 		idx++;
 
-	atomic_inc_64(&((kstat_named_t *)shk->private)[idx].value.ui64);
+	atomic_inc_64(&((kstat_named_t *)shk->priv)[idx].value.ui64);
 }
 
 /*