21 files changed, 111 insertions, 103 deletions

diff --git a/include/libzfs.h b/include/libzfs.h
index fe420de4d4de..6b4ead8182d6 100644
--- a/include/libzfs.h
+++ b/include/libzfs.h
@@ -423,9 +423,9 @@ typedef enum {
 	ZPOOL_STATUS_OK
 } zpool_status_t;
 
-_LIBZFS_H zpool_status_t zpool_get_status(zpool_handle_t *, char **,
+_LIBZFS_H zpool_status_t zpool_get_status(zpool_handle_t *, const char **,
     zpool_errata_t *);
-_LIBZFS_H zpool_status_t zpool_import_status(nvlist_t *, char **,
+_LIBZFS_H zpool_status_t zpool_import_status(nvlist_t *, const char **,
     zpool_errata_t *);
 
 /*
@@ -870,8 +870,9 @@ _LIBZFS_H int zfs_unmountall(zfs_handle_t *, int);
 _LIBZFS_H int zfs_mount_delegation_check(void);
 
 #if defined(__linux__) || defined(__APPLE__)
-_LIBZFS_H int zfs_parse_mount_options(char *mntopts, unsigned long *mntflags,
-    unsigned long *zfsflags, int sloppy, char *badopt, char *mtabopt);
+_LIBZFS_H int zfs_parse_mount_options(const char *mntopts,
+    unsigned long *mntflags, unsigned long *zfsflags, int sloppy, char *badopt,
+    char *mtabopt);
 _LIBZFS_H void zfs_adjust_mount_options(zfs_handle_t *zhp, const char *mntpoint,
     char *mntopts, char *mtabopt);
 #endif
@@ -910,7 +911,7 @@ _LIBZFS_H int libzfs_run_process_get_stdout_nopath(const char *, char *[],
 
 _LIBZFS_H void libzfs_free_str_array(char **, int);
 
-_LIBZFS_H int libzfs_envvar_is_set(char *);
+_LIBZFS_H boolean_t libzfs_envvar_is_set(const char *);
 
 /*
  * Utility functions for zfs version
diff --git a/include/libzutil.h b/include/libzutil.h
index d0d5632c027a..a46059b128f9 100644
--- a/include/libzutil.h
+++ b/include/libzutil.h
@@ -155,9 +155,9 @@ struct zfs_cmd;
 #define	ANSI_RESET	"\033[0m"
 #define	ANSI_BOLD	"\033[1m"
 
-_LIBZUTIL_H void color_start(char *color);
+_LIBZUTIL_H void color_start(const char *color);
 _LIBZUTIL_H void color_end(void);
-_LIBZUTIL_H int printf_color(char *color, char *format, ...);
+_LIBZUTIL_H int printf_color(const char *color, const char *format, ...);
 
 _LIBZUTIL_H const char *zfs_basename(const char *path);
 _LIBZUTIL_H ssize_t zfs_dirnamelen(const char *path);
diff --git a/include/os/freebsd/spl/sys/kmem.h b/include/os/freebsd/spl/sys/kmem.h
index dc3b4f5d7877..a81cb1fb521d 100644
--- a/include/os/freebsd/spl/sys/kmem.h
+++ b/include/os/freebsd/spl/sys/kmem.h
@@ -73,7 +73,7 @@ extern uint64_t spl_kmem_cache_entry_size(kmem_cache_t *cache);
 void *zfs_kmem_alloc(size_t size, int kmflags);
 void zfs_kmem_free(void *buf, size_t size);
 uint64_t kmem_size(void);
-kmem_cache_t *kmem_cache_create(char *name, size_t bufsize, size_t align,
+kmem_cache_t *kmem_cache_create(const char *name, size_t bufsize, size_t align,
     int (*constructor)(void *, void *, int), void (*destructor)(void *, void *),
     void (*reclaim)(void *) __unused, void *private, vmem_t *vmp, int cflags);
 void kmem_cache_destroy(kmem_cache_t *cache);
diff --git a/include/os/linux/spl/sys/kmem_cache.h b/include/os/linux/spl/sys/kmem_cache.h
index 48006ec5d27e..bd0ad5052d3d 100644
--- a/include/os/linux/spl/sys/kmem_cache.h
+++ b/include/os/linux/spl/sys/kmem_cache.h
@@ -183,7 +183,7 @@ typedef struct spl_kmem_cache {
 } spl_kmem_cache_t;
 #define	kmem_cache_t		spl_kmem_cache_t
 
-extern spl_kmem_cache_t *spl_kmem_cache_create(char *name, size_t size,
+extern spl_kmem_cache_t *spl_kmem_cache_create(const char *name, size_t size,
     size_t align, spl_kmem_ctor_t ctor, spl_kmem_dtor_t dtor,
     void *reclaim, void *priv, void *vmp, int flags);
 extern void spl_kmem_cache_set_move(spl_kmem_cache_t *,
diff --git a/include/sys/arc.h b/include/sys/arc.h
index 4f9bfe48d7e3..90b99c6cb1a3 100644
--- a/include/sys/arc.h
+++ b/include/sys/arc.h
@@ -264,12 +264,12 @@ int arc_untransform(arc_buf_t *buf, spa_t *spa, const zbookmark_phys_t *zb,
 void arc_convert_to_raw(arc_buf_t *buf, uint64_t dsobj, boolean_t byteorder,
     dmu_object_type_t ot, const uint8_t *salt, const uint8_t *iv,
     const uint8_t *mac);
-arc_buf_t *arc_alloc_buf(spa_t *spa, void *tag, arc_buf_contents_t type,
+arc_buf_t *arc_alloc_buf(spa_t *spa, const void *tag, arc_buf_contents_t type,
     int32_t size);
-arc_buf_t *arc_alloc_compressed_buf(spa_t *spa, void *tag,
+arc_buf_t *arc_alloc_compressed_buf(spa_t *spa, const void *tag,
     uint64_t psize, uint64_t lsize, enum zio_compress compression_type,
     uint8_t complevel);
-arc_buf_t *arc_alloc_raw_buf(spa_t *spa, void *tag, uint64_t dsobj,
+arc_buf_t *arc_alloc_raw_buf(spa_t *spa, const void *tag, uint64_t dsobj,
     boolean_t byteorder, const uint8_t *salt, const uint8_t *iv,
     const uint8_t *mac, dmu_object_type_t ot, uint64_t psize, uint64_t lsize,
     enum zio_compress compression_type, uint8_t complevel);
diff --git a/include/sys/dbuf.h b/include/sys/dbuf.h
index 60f8d5d74d6e..959e111cee7a 100644
--- a/include/sys/dbuf.h
+++ b/include/sys/dbuf.h
@@ -339,12 +339,12 @@ int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);
 
 void dbuf_rm_spill(struct dnode *dn, dmu_tx_t *tx);
 
-dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, void *tag);
+dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, const void *tag);
 dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
-    void *tag);
+    const void *tag);
 int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid,
     boolean_t fail_sparse, boolean_t fail_uncached,
-    void *tag, dmu_buf_impl_t **dbp);
+    const void *tag, dmu_buf_impl_t **dbp);
 
 int dbuf_prefetch_impl(struct dnode *dn, int64_t level, uint64_t blkid,
     zio_priority_t prio, arc_flags_t aflags, dbuf_prefetch_fn cb,
@@ -352,13 +352,14 @@ int dbuf_prefetch_impl(struct dnode *dn, int64_t level, uint64_t blkid,
 int dbuf_prefetch(struct dnode *dn, int64_t level, uint64_t blkid,
     zio_priority_t prio, arc_flags_t aflags);
 
-void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
+void dbuf_add_ref(dmu_buf_impl_t *db, const void *tag);
 boolean_t dbuf_try_add_ref(dmu_buf_t *db, objset_t *os, uint64_t obj,
-    uint64_t blkid, void *tag);
+    uint64_t blkid, const void *tag);
 uint64_t dbuf_refcount(dmu_buf_impl_t *db);
 
-void dbuf_rele(dmu_buf_impl_t *db, void *tag);
-void dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag, boolean_t evicting);
+void dbuf_rele(dmu_buf_impl_t *db, const void *tag);
+void dbuf_rele_and_unlock(dmu_buf_impl_t *db, const void *tag,
+    boolean_t evicting);
 
 dmu_buf_impl_t *dbuf_find(struct objset *os, uint64_t object, uint8_t level,
     uint64_t blkid);
@@ -385,8 +386,10 @@ void dbuf_destroy(dmu_buf_impl_t *db);
 void dbuf_unoverride(dbuf_dirty_record_t *dr);
 void dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx);
 void dbuf_release_bp(dmu_buf_impl_t *db);
-db_lock_type_t dmu_buf_lock_parent(dmu_buf_impl_t *db, krw_t rw, void *tag);
-void dmu_buf_unlock_parent(dmu_buf_impl_t *db, db_lock_type_t type, void *tag);
+db_lock_type_t dmu_buf_lock_parent(dmu_buf_impl_t *db, krw_t rw,
+    const void *tag);
+void dmu_buf_unlock_parent(dmu_buf_impl_t *db, db_lock_type_t type,
+    const void *tag);
 
 void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,
     struct dmu_tx *);
diff --git a/include/sys/dmu.h b/include/sys/dmu.h
index 03513f9f2c6c..6bd7a3e9a412 100644
--- a/include/sys/dmu.h
+++ b/include/sys/dmu.h
@@ -319,11 +319,12 @@ void zfs_znode_byteswap(void *buf, size_t size);
 typedef void dmu_objset_create_sync_func_t(objset_t *os, void *arg,
     cred_t *cr, dmu_tx_t *tx);
 
-int dmu_objset_hold(const char *name, void *tag, objset_t **osp);
+int dmu_objset_hold(const char *name, const void *tag, objset_t **osp);
 int dmu_objset_own(const char *name, dmu_objset_type_t type,
-    boolean_t readonly, boolean_t key_required, void *tag, objset_t **osp);
-void dmu_objset_rele(objset_t *os, void *tag);
-void dmu_objset_disown(objset_t *os, boolean_t key_required, void *tag);
+    boolean_t readonly, boolean_t key_required, const void *tag,
+    objset_t **osp);
+void dmu_objset_rele(objset_t *os, const void *tag);
+void dmu_objset_disown(objset_t *os, boolean_t key_required, const void *tag);
 int dmu_objset_open_ds(struct dsl_dataset *ds, objset_t **osp);
 
 void dmu_objset_evict_dbufs(objset_t *os);
@@ -407,7 +408,7 @@ uint64_t dmu_object_alloc_dnsize(objset_t *os, dmu_object_type_t ot,
     int dnodesize, dmu_tx_t *tx);
 uint64_t dmu_object_alloc_hold(objset_t *os, dmu_object_type_t ot,
     int blocksize, int indirect_blockshift, dmu_object_type_t bonustype,
-    int bonuslen, int dnodesize, dnode_t **allocated_dnode, void *tag,
+    int bonuslen, int dnodesize, dnode_t **allocated_dnode, const void *tag,
     dmu_tx_t *tx);
 int dmu_object_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
@@ -524,8 +525,9 @@ void dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp,
  *
  * Returns ENOENT, EIO, or 0.
  */
-int dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **dbp);
-int dmu_bonus_hold_by_dnode(dnode_t *dn, void *tag, dmu_buf_t **dbp,
+int dmu_bonus_hold(objset_t *os, uint64_t object, const void *tag,
+    dmu_buf_t **dbp);
+int dmu_bonus_hold_by_dnode(dnode_t *dn, const void *tag, dmu_buf_t **dbp,
     uint32_t flags);
 int dmu_bonus_max(void);
 int dmu_set_bonus(dmu_buf_t *, int, dmu_tx_t *);
@@ -537,11 +539,11 @@ int dmu_rm_spill(objset_t *, uint64_t, dmu_tx_t *);
  * Special spill buffer support used by "SA" framework
  */
 
-int dmu_spill_hold_by_bonus(dmu_buf_t *bonus, uint32_t flags, void *tag,
+int dmu_spill_hold_by_bonus(dmu_buf_t *bonus, uint32_t flags, const void *tag,
     dmu_buf_t **dbp);
 int dmu_spill_hold_by_dnode(dnode_t *dn, uint32_t flags,
-    void *tag, dmu_buf_t **dbp);
-int dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
+    const void *tag, dmu_buf_t **dbp);
+int dmu_spill_hold_existing(dmu_buf_t *bonus, const void *tag, dmu_buf_t **dbp);
 
 /*
  * Obtain the DMU buffer from the specified object which contains the
@@ -558,13 +560,14 @@ int dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
  * The object number must be a valid, allocated object number.
  */
 int dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
-    void *tag, dmu_buf_t **, int flags);
+    const void *tag, dmu_buf_t **, int flags);
 int dmu_buf_hold_array(objset_t *os, uint64_t object, uint64_t offset,
-    uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp);
+    uint64_t length, int read, const void *tag, int *numbufsp,
+    dmu_buf_t ***dbpp);
 int dmu_buf_hold_by_dnode(dnode_t *dn, uint64_t offset,
-    void *tag, dmu_buf_t **dbp, int flags);
+    const void *tag, dmu_buf_t **dbp, int flags);
 int dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset,
-    uint64_t length, boolean_t read, void *tag, int *numbufsp,
+    uint64_t length, boolean_t read, const void *tag, int *numbufsp,
     dmu_buf_t ***dbpp, uint32_t flags);
 /*
  * Add a reference to a dmu buffer that has already been held via
@@ -580,9 +583,9 @@ void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
  * one hold by a user other than the syncer.
  */
 boolean_t dmu_buf_try_add_ref(dmu_buf_t *, objset_t *os, uint64_t object,
-    uint64_t blkid, void *tag);
+    uint64_t blkid, const void *tag);
 
-void dmu_buf_rele(dmu_buf_t *db, void *tag);
+void dmu_buf_rele(dmu_buf_t *db, const void *tag);
 uint64_t dmu_buf_refcount(dmu_buf_t *db);
 uint64_t dmu_buf_user_refcount(dmu_buf_t *db);
 
@@ -597,9 +600,9 @@ uint64_t dmu_buf_user_refcount(dmu_buf_t *db);
  * individually with dmu_buf_rele.
  */
 int dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset,
-    uint64_t length, boolean_t read, void *tag,
+    uint64_t length, boolean_t read, const void *tag,
     int *numbufsp, dmu_buf_t ***dbpp);
-void dmu_buf_rele_array(dmu_buf_t **, int numbufs, void *tag);
+void dmu_buf_rele_array(dmu_buf_t **, int numbufs, const void *tag);
 
 typedef void dmu_buf_evict_func_t(void *user_ptr);
 
@@ -895,12 +898,12 @@ typedef struct dmu_object_type_info {
 	boolean_t		ot_metadata;
 	boolean_t		ot_dbuf_metadata_cache;
 	boolean_t		ot_encrypt;
-	char			*ot_name;
+	const char		*ot_name;
 } dmu_object_type_info_t;
 
 typedef const struct dmu_object_byteswap_info {
 	arc_byteswap_func_t	 ob_func;
-	char			*ob_name;
+	const char		*ob_name;
 } dmu_object_byteswap_info_t;
 
 extern const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES];
diff --git a/include/sys/dmu_impl.h b/include/sys/dmu_impl.h
index def4aadba1d0..95ec11ce2400 100644
--- a/include/sys/dmu_impl.h
+++ b/include/sys/dmu_impl.h
@@ -248,7 +248,7 @@ typedef struct dmu_sendstatus {
 void dmu_object_zapify(objset_t *, uint64_t, dmu_object_type_t, dmu_tx_t *);
 void dmu_object_free_zapified(objset_t *, uint64_t, dmu_tx_t *);
 int dmu_buf_hold_noread(objset_t *, uint64_t, uint64_t,
-    void *, dmu_buf_t **);
+    const void *, dmu_buf_t **);
 
 #ifdef	__cplusplus
 }
diff --git a/include/sys/dmu_objset.h b/include/sys/dmu_objset.h
index 7ade2dc91247..782338fd210a 100644
--- a/include/sys/dmu_objset.h
+++ b/include/sys/dmu_objset.h
@@ -201,19 +201,19 @@ struct objset {
 #define	DMU_PROJECTUSED_DNODE(os) ((os)->os_projectused_dnode.dnh_dnode)
 
 /* called from zpl */
-int dmu_objset_hold(const char *name, void *tag, objset_t **osp);
-int dmu_objset_hold_flags(const char *name, boolean_t decrypt, void *tag,
+int dmu_objset_hold(const char *name, const void *tag, objset_t **osp);
+int dmu_objset_hold_flags(const char *name, boolean_t decrypt, const void *tag,
     objset_t **osp);
 int dmu_objset_own(const char *name, dmu_objset_type_t type,
-    boolean_t readonly, boolean_t decrypt, void *tag, objset_t **osp);
+    boolean_t readonly, boolean_t decrypt, const void *tag, objset_t **osp);
 int dmu_objset_own_obj(struct dsl_pool *dp, uint64_t obj,
     dmu_objset_type_t type, boolean_t readonly, boolean_t decrypt,
-    void *tag, objset_t **osp);
+    const void *tag, objset_t **osp);
 void dmu_objset_refresh_ownership(struct dsl_dataset *ds,
-    struct dsl_dataset **newds, boolean_t decrypt, void *tag);
-void dmu_objset_rele(objset_t *os, void *tag);
-void dmu_objset_rele_flags(objset_t *os, boolean_t decrypt, void *tag);
-void dmu_objset_disown(objset_t *os, boolean_t decrypt, void *tag);
+    struct dsl_dataset **newds, boolean_t decrypt, const void *tag);
+void dmu_objset_rele(objset_t *os, const void *tag);
+void dmu_objset_rele_flags(objset_t *os, boolean_t decrypt, const void *tag);
+void dmu_objset_disown(objset_t *os, boolean_t decrypt, const void *tag);
 int dmu_objset_from_ds(struct dsl_dataset *ds, objset_t **osp);
 
 void dmu_objset_stats(objset_t *os, nvlist_t *nv);
diff --git a/include/sys/dnode.h b/include/sys/dnode.h
index 33d9389d5a38..9745ae5bb651 100644
--- a/include/sys/dnode.h
+++ b/include/sys/dnode.h
@@ -334,7 +334,7 @@ struct dnode {
 	kcondvar_t dn_notxholds;
 	kcondvar_t dn_nodnholds;
 	enum dnode_dirtycontext dn_dirtyctx;
-	void *dn_dirtyctx_firstset;		/* dbg: contents meaningless */
+	const void *dn_dirtyctx_firstset;	/* dbg: contents meaningless */
 
 	/* protected by own devices */
 	zfs_refcount_t dn_tx_holds;
@@ -418,16 +418,16 @@ void dnode_setbonus_type(dnode_t *dn, dmu_object_type_t, dmu_tx_t *tx);
 void dnode_rm_spill(dnode_t *dn, dmu_tx_t *tx);
 
 int dnode_hold(struct objset *dd, uint64_t object,
-    void *ref, dnode_t **dnp);
+    const void *ref, dnode_t **dnp);
 int dnode_hold_impl(struct objset *dd, uint64_t object, int flag, int dn_slots,
-    void *ref, dnode_t **dnp);
-boolean_t dnode_add_ref(dnode_t *dn, void *ref);
-void dnode_rele(dnode_t *dn, void *ref);
-void dnode_rele_and_unlock(dnode_t *dn, void *tag, boolean_t evicting);
+    const void *ref, dnode_t **dnp);
+boolean_t dnode_add_ref(dnode_t *dn, const void *ref);
+void dnode_rele(dnode_t *dn, const void *ref);
+void dnode_rele_and_unlock(dnode_t *dn, const void *tag, boolean_t evicting);
 int dnode_try_claim(objset_t *os, uint64_t object, int slots);
 boolean_t dnode_is_dirty(dnode_t *dn);
 void dnode_setdirty(dnode_t *dn, dmu_tx_t *tx);
-void dnode_set_dirtyctx(dnode_t *dn, dmu_tx_t *tx, void *tag);
+void dnode_set_dirtyctx(dnode_t *dn, dmu_tx_t *tx, const void *tag);
 void dnode_sync(dnode_t *dn, dmu_tx_t *tx);
 void dnode_allocate(dnode_t *dn, dmu_object_type_t ot, int blocksize, int ibs,
     dmu_object_type_t bonustype, int bonuslen, int dn_slots, dmu_tx_t *tx);
diff --git a/include/sys/dsl_dataset.h b/include/sys/dsl_dataset.h
index 561d49dac4bf..25f86bce2e63 100644
--- a/include/sys/dsl_dataset.h
+++ b/include/sys/dsl_dataset.h
@@ -220,7 +220,7 @@ typedef struct dsl_dataset {
 	kmutex_t ds_lock;
 	objset_t *ds_objset;
 	uint64_t ds_userrefs;
-	void *ds_owner;
+	const void *ds_owner;
 
 	/*
 	 * Long holds prevent the ds from being destroyed; they allow the
@@ -319,32 +319,34 @@ typedef enum ds_hold_flags {
 	DS_HOLD_FLAG_DECRYPT	= 1 << 0 /* needs access to encrypted data */
 } ds_hold_flags_t;
 
-int dsl_dataset_hold(struct dsl_pool *dp, const char *name, void *tag,
+int dsl_dataset_hold(struct dsl_pool *dp, const char *name, const void *tag,
     dsl_dataset_t **dsp);
 int dsl_dataset_hold_flags(struct dsl_pool *dp, const char *name,
-    ds_hold_flags_t flags, void *tag, dsl_dataset_t **dsp);
+    ds_hold_flags_t flags, const void *tag, dsl_dataset_t **dsp);
 boolean_t dsl_dataset_try_add_ref(struct dsl_pool *dp, dsl_dataset_t *ds,
-    void *tag);
+    const void *tag);
 int dsl_dataset_create_key_mapping(dsl_dataset_t *ds);
 int dsl_dataset_hold_obj_flags(struct dsl_pool *dp, uint64_t dsobj,
-    ds_hold_flags_t flags, void *tag, dsl_dataset_t **);
+    ds_hold_flags_t flags, const void *tag, dsl_dataset_t **);
 void dsl_dataset_remove_key_mapping(dsl_dataset_t *ds);
 int dsl_dataset_hold_obj(struct dsl_pool *dp, uint64_t dsobj,
-    void *tag, dsl_dataset_t **);
+    const void *tag, dsl_dataset_t **);
 void dsl_dataset_rele_flags(dsl_dataset_t *ds, ds_hold_flags_t flags,
-    void *tag);
-void dsl_dataset_rele(dsl_dataset_t *ds, void *tag);
+    const void *tag);
+void dsl_dataset_rele(dsl_dataset_t *ds, const void *tag);
 int dsl_dataset_own(struct dsl_pool *dp, const char *name,
-    ds_hold_flags_t flags, void *tag, dsl_dataset_t **dsp);
+    ds_hold_flags_t flags, const void *tag, dsl_dataset_t **dsp);
 int dsl_dataset_own_force(struct dsl_pool *dp, const char *name,
-    ds_hold_flags_t flags, void *tag, dsl_dataset_t **dsp);
+    ds_hold_flags_t flags, const void *tag, dsl_dataset_t **dsp);
 int dsl_dataset_own_obj(struct dsl_pool *dp, uint64_t dsobj,
-    ds_hold_flags_t flags, void *tag, dsl_dataset_t **dsp);
+    ds_hold_flags_t flags, const void *tag, dsl_dataset_t **dsp);
 int dsl_dataset_own_obj_force(struct dsl_pool *dp, uint64_t dsobj,
-    ds_hold_flags_t flags, void *tag, dsl_dataset_t **dsp);
-void dsl_dataset_disown(dsl_dataset_t *ds, ds_hold_flags_t flags, void *tag);
+    ds_hold_flags_t flags, const void *tag, dsl_dataset_t **dsp);
+void dsl_dataset_disown(dsl_dataset_t *ds, ds_hold_flags_t flags,
+    const void *tag);
 void dsl_dataset_name(dsl_dataset_t *ds, char *name);
-boolean_t dsl_dataset_tryown(dsl_dataset_t *ds, void *tag, boolean_t override);
+boolean_t dsl_dataset_tryown(dsl_dataset_t *ds, const void *tag,
+    boolean_t override);
 int dsl_dataset_namelen(dsl_dataset_t *ds);
 boolean_t dsl_dataset_has_owner(dsl_dataset_t *ds);
 uint64_t dsl_dataset_create_sync(dsl_dir_t *pds, const char *lastname,
diff --git a/include/sys/dsl_pool.h b/include/sys/dsl_pool.h
index 15e0efc3e773..5bb5ef20d5b1 100644
--- a/include/sys/dsl_pool.h
+++ b/include/sys/dsl_pool.h
@@ -177,9 +177,9 @@ void dsl_pool_mos_diduse_space(dsl_pool_t *dp,
 void dsl_pool_ckpoint_diduse_space(dsl_pool_t *dp,
     int64_t used, int64_t comp, int64_t uncomp);
 boolean_t dsl_pool_need_dirty_delay(dsl_pool_t *dp);
-void dsl_pool_config_enter(dsl_pool_t *dp, void *tag);
-void dsl_pool_config_enter_prio(dsl_pool_t *dp, void *tag);
-void dsl_pool_config_exit(dsl_pool_t *dp, void *tag);
+void dsl_pool_config_enter(dsl_pool_t *dp, const void *tag);
+void dsl_pool_config_enter_prio(dsl_pool_t *dp, const void *tag);
+void dsl_pool_config_exit(dsl_pool_t *dp, const void *tag);
 boolean_t dsl_pool_config_held(dsl_pool_t *dp);
 boolean_t dsl_pool_config_held_writer(dsl_pool_t *dp);
 
@@ -192,8 +192,8 @@ int dsl_pool_user_release(dsl_pool_t *dp, uint64_t dsobj,
     const char *tag, dmu_tx_t *tx);
 void dsl_pool_clean_tmp_userrefs(dsl_pool_t *dp);
 int dsl_pool_open_special_dir(dsl_pool_t *dp, const char *name, dsl_dir_t **);
-int dsl_pool_hold(const char *name, void *tag, dsl_pool_t **dp);
-void dsl_pool_rele(dsl_pool_t *dp, void *tag);
+int dsl_pool_hold(const char *name, const void *tag, dsl_pool_t **dp);
+void dsl_pool_rele(dsl_pool_t *dp, const void *tag);
 
 void dsl_pool_create_obsolete_bpobj(dsl_pool_t *dp, dmu_tx_t *tx);
 void dsl_pool_destroy_obsolete_bpobj(dsl_pool_t *dp, dmu_tx_t *tx);
diff --git a/include/sys/rrwlock.h b/include/sys/rrwlock.h
index 8d296ef28ffa..51ac364af519 100644
--- a/include/sys/rrwlock.h
+++ b/include/sys/rrwlock.h
@@ -72,11 +72,11 @@ typedef struct rrwlock {
  */
 void rrw_init(rrwlock_t *rrl, boolean_t track_all);
 void rrw_destroy(rrwlock_t *rrl);
-void rrw_enter(rrwlock_t *rrl, krw_t rw, void *tag);
-void rrw_enter_read(rrwlock_t *rrl, void *tag);
-void rrw_enter_read_prio(rrwlock_t *rrl, void *tag);
+void rrw_enter(rrwlock_t *rrl, krw_t rw, const void *tag);
+void rrw_enter_read(rrwlock_t *rrl, const void *tag);
+void rrw_enter_read_prio(rrwlock_t *rrl, const void *tag);
 void rrw_enter_write(rrwlock_t *rrl);
-void rrw_exit(rrwlock_t *rrl, void *tag);
+void rrw_exit(rrwlock_t *rrl, const void *tag);
 boolean_t rrw_held(rrwlock_t *rrl, krw_t rw);
 void rrw_tsd_destroy(void *arg);
 
@@ -99,10 +99,10 @@ typedef struct rrmlock {
 
 void rrm_init(rrmlock_t *rrl, boolean_t track_all);
 void rrm_destroy(rrmlock_t *rrl);
-void rrm_enter(rrmlock_t *rrl, krw_t rw, void *tag);
-void rrm_enter_read(rrmlock_t *rrl, void *tag);
+void rrm_enter(rrmlock_t *rrl, krw_t rw, const void *tag);
+void rrm_enter_read(rrmlock_t *rrl, const void *tag);
 void rrm_enter_write(rrmlock_t *rrl);
-void rrm_exit(rrmlock_t *rrl, void *tag);
+void rrm_exit(rrmlock_t *rrl, const void *tag);
 boolean_t rrm_held(rrmlock_t *rrl, krw_t rw);
 
 #define	RRM_READ_HELD(x)	rrm_held(x, RW_READER)
diff --git a/include/sys/sa.h b/include/sys/sa.h
index 32f6bd0ccd95..709018bde612 100644
--- a/include/sys/sa.h
+++ b/include/sys/sa.h
@@ -49,7 +49,7 @@ typedef uint16_t	sa_attr_type_t;
  * Attribute to register support for.
  */
 typedef struct sa_attr_reg {
-	char 			*sa_name;	/* attribute name */
+	const char 		*sa_name;	/* attribute name */
 	uint16_t 		sa_length;
 	sa_bswap_type_t		sa_byteswap;	/* bswap function enum */
 	sa_attr_type_t 		sa_attr; /* filled in during registration */
diff --git a/include/sys/spa.h b/include/sys/spa.h
index 442bc7792b2b..62fad3378e56 100644
--- a/include/sys/spa.h
+++ b/include/sys/spa.h
@@ -606,7 +606,7 @@ typedef struct blkptr {
 
 #define	SNPRINTF_BLKPTR(func, ws, buf, size, bp, type, checksum, compress) \
 {									\
-	static const char *copyname[] =					\
+	static const char *const copyname[] =				\
 	    { "zero", "single", "double", "triple" };			\
 	int len = 0;							\
 	int copies = 0;							\
@@ -743,8 +743,8 @@ typedef enum trim_type {
 } trim_type_t;
 
 /* state manipulation functions */
-extern int spa_open(const char *pool, spa_t **, void *tag);
-extern int spa_open_rewind(const char *pool, spa_t **, void *tag,
+extern int spa_open(const char *pool, spa_t **, const void *tag);
+extern int spa_open_rewind(const char *pool, spa_t **, const void *tag,
     nvlist_t *policy, nvlist_t **config);
 extern int spa_get_stats(const char *pool, nvlist_t **config, char *altroot,
     size_t buflen);
@@ -801,8 +801,8 @@ extern int spa_vdev_trim(spa_t *spa, nvlist_t *nv, uint64_t cmd_type,
     uint64_t rate, boolean_t partial, boolean_t secure, nvlist_t *vdev_errlist);
 extern int spa_vdev_setpath(spa_t *spa, uint64_t guid, const char *newpath);
 extern int spa_vdev_setfru(spa_t *spa, uint64_t guid, const char *newfru);
-extern int spa_vdev_split_mirror(spa_t *spa, char *newname, nvlist_t *config,
-    nvlist_t *props, boolean_t exp);
+extern int spa_vdev_split_mirror(spa_t *spa, const char *newname,
+    nvlist_t *config, nvlist_t *props, boolean_t exp);
 
 /* spare state (which is global across all pools) */
 extern void spa_spare_add(vdev_t *vd);
@@ -860,9 +860,9 @@ extern void spa_remove(spa_t *spa);
 extern spa_t *spa_next(spa_t *prev);
 
 /* Refcount functions */
-extern void spa_open_ref(spa_t *spa, void *tag);
-extern void spa_close(spa_t *spa, void *tag);
-extern void spa_async_close(spa_t *spa, void *tag);
+extern void spa_open_ref(spa_t *spa, const void *tag);
+extern void spa_close(spa_t *spa, const void *tag);
+extern void spa_async_close(spa_t *spa, const void *tag);
 extern boolean_t spa_refcount_zero(spa_t *spa);
 
 #define	SCL_NONE	0x00
@@ -971,7 +971,8 @@ extern int spa_import_progress_set_state(uint64_t pool_guid,
     spa_load_state_t spa_load_state);
 
 /* Pool configuration locks */
-extern int spa_config_tryenter(spa_t *spa, int locks, void *tag, krw_t rw);
+extern int spa_config_tryenter(spa_t *spa, int locks, const void *tag,
+    krw_t rw);
 extern void spa_config_enter(spa_t *spa, int locks, const void *tag, krw_t rw);
 extern void spa_config_exit(spa_t *spa, int locks, const void *tag);
 extern int spa_config_held(spa_t *spa, int locks, krw_t rw);
diff --git a/include/sys/zfs_fuid.h b/include/sys/zfs_fuid.h
index b5b37db29468..1975e57cf62b 100644
--- a/include/sys/zfs_fuid.h
+++ b/include/sys/zfs_fuid.h
@@ -112,15 +112,13 @@ extern zfs_fuid_info_t *zfs_fuid_info_alloc(void);
 extern void zfs_fuid_info_free(zfs_fuid_info_t *);
 extern boolean_t zfs_groupmember(zfsvfs_t *, uint64_t, cred_t *);
 void zfs_fuid_sync(zfsvfs_t *, dmu_tx_t *);
-extern int zfs_fuid_find_by_domain(zfsvfs_t *, const char *domain,
-    char **retdomain, boolean_t addok);
 extern const char *zfs_fuid_find_by_idx(zfsvfs_t *zfsvfs, uint32_t idx);
 extern void zfs_fuid_txhold(zfsvfs_t *zfsvfs, dmu_tx_t *tx);
 extern int zfs_id_to_fuidstr(zfsvfs_t *zfsvfs, const char *domain, uid_t rid,
     char *buf, size_t len, boolean_t addok);
 #endif
 
-char *zfs_fuid_idx_domain(avl_tree_t *, uint32_t);
+const char *zfs_fuid_idx_domain(avl_tree_t *, uint32_t);
 void zfs_fuid_avl_tree_create(avl_tree_t *, avl_tree_t *);
 uint64_t zfs_fuid_table_load(objset_t *, uint64_t, avl_tree_t *, avl_tree_t *);
 void zfs_fuid_table_destroy(avl_tree_t *, avl_tree_t *);
diff --git a/include/sys/zio_checksum.h b/include/sys/zio_checksum.h
index a2ce5081644c..989f125e6afd 100644
--- a/include/sys/zio_checksum.h
+++ b/include/sys/zio_checksum.h
@@ -90,7 +90,7 @@ typedef const struct zio_checksum_info {
 	zio_checksum_tmpl_init_t	*ci_tmpl_init;
 	zio_checksum_tmpl_free_t	*ci_tmpl_free;
 	zio_checksum_flags_t		ci_flags;
-	char				*ci_name;	/* descriptive name */
+	const char			*ci_name;	/* descriptive name */
 } zio_checksum_info_t;
 
 typedef struct zio_bad_cksum {
@@ -102,7 +102,7 @@ typedef struct zio_bad_cksum {
 	uint8_t			zbc_has_cksum;	/* expected/actual valid */
 } zio_bad_cksum_t;
 
-_SYS_ZIO_CHECKSUM_H zio_checksum_info_t
+_SYS_ZIO_CHECKSUM_H const zio_checksum_info_t
     zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS];
 
 /*
diff --git a/include/sys/zio_compress.h b/include/sys/zio_compress.h
index 4a22ad2a2742..26600b43bb49 100644
--- a/include/sys/zio_compress.h
+++ b/include/sys/zio_compress.h
@@ -145,14 +145,14 @@ typedef int zio_decompress_abd_func_t(abd_t *src, void *dst,
  * Information about each compression function.
  */
 typedef const struct zio_compress_info {
-	char				*ci_name;
+	const char			*ci_name;
 	int				ci_level;
 	zio_compress_func_t		*ci_compress;
 	zio_decompress_func_t		*ci_decompress;
 	zio_decompresslevel_func_t	*ci_decompress_level;
 } zio_compress_info_t;
 
-extern zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS];
+extern const zio_compress_info_t zio_compress_table[ZIO_COMPRESS_FUNCTIONS];
 
 /*
  * lz4 compression init & free
diff --git a/include/sys/zio_crypt.h b/include/sys/zio_crypt.h
index f1edd76f0d8e..6a3efabb0405 100644
--- a/include/sys/zio_crypt.h
+++ b/include/sys/zio_crypt.h
@@ -67,7 +67,7 @@ typedef struct zio_crypt_info {
 	size_t ci_keylen;
 
 	/* human-readable name of the encryption algorithm */
-	char *ci_name;
+	const char *ci_name;
 } zio_crypt_info_t;
 
 extern const zio_crypt_info_t zio_crypt_table[ZIO_CRYPT_FUNCTIONS];
diff --git a/include/zfs_comutil.h b/include/zfs_comutil.h
index ea2da4a15f1d..51625a5cd03d 100644
--- a/include/zfs_comutil.h
+++ b/include/zfs_comutil.h
@@ -34,7 +34,7 @@ extern "C" {
 #endif
 
 _ZFS_COMUTIL_H boolean_t zfs_allocatable_devs(nvlist_t *);
-_ZFS_COMUTIL_H boolean_t zfs_special_devs(nvlist_t *, char *);
+_ZFS_COMUTIL_H boolean_t zfs_special_devs(nvlist_t *, const char *);
 _ZFS_COMUTIL_H void zpool_get_load_policy(nvlist_t *, zpool_load_policy_t *);
 
 _ZFS_COMUTIL_H int zfs_zpl_version_map(int spa_version);
diff --git a/include/zfs_deleg.h b/include/zfs_deleg.h
index 77f64786b089..760d16aefcf3 100644
--- a/include/zfs_deleg.h
+++ b/include/zfs_deleg.h
@@ -81,7 +81,7 @@ typedef enum {
 } zfs_deleg_note_t;
 
 typedef struct zfs_deleg_perm_tab {
-	char *z_perm;
+	const char *z_perm;
 	zfs_deleg_note_t z_note;
 } zfs_deleg_perm_tab_t;