Remaining {=> const} char|void *tag

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13348

38 files changed, 138 insertions, 127 deletions

diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index d3a68171adfb..13994c3bbf8a 100644
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -3024,7 +3024,7 @@ static objset_t *sa_os = NULL;
 static sa_attr_type_t *sa_attr_table = NULL;
 
 static int
-open_objset(const char *path, void *tag, objset_t **osp)
+open_objset(const char *path, const void *tag, objset_t **osp)
 {
 	int err;
 	uint64_t sa_attrs = 0;
@@ -3068,7 +3068,7 @@ open_objset(const char *path, void *tag, objset_t **osp)
 }
 
 static void
-close_objset(objset_t *os, void *tag)
+close_objset(objset_t *os, const void *tag)
 {
 	VERIFY3P(os, ==, sa_os);
 	if (os->os_sa != NULL)
diff --git a/cmd/zfs/zfs_main.c b/cmd/zfs/zfs_main.c
index 1a2106c2efba..e71959c3ca59 100644
--- a/cmd/zfs/zfs_main.c
+++ b/cmd/zfs/zfs_main.c
@@ -6438,7 +6438,7 @@ print_holds(boolean_t scripted, int nwidth, int tagwidth, nvlist_t *nvl)
 		(void) nvpair_value_nvlist(nvp, &nvl2);
 		while ((nvp2 = nvlist_next_nvpair(nvl2, nvp2)) != NULL) {
 			char tsbuf[DATETIME_BUF_LEN];
-			char *tagname = nvpair_name(nvp2);
+			const char *tagname = nvpair_name(nvp2);
 			uint64_t val = 0;
 			time_t time;
 			struct tm t;
diff --git a/cmd/zhack.c b/cmd/zhack.c
index 71a2c5ae6c3d..8221a67d5131 100644
--- a/cmd/zhack.c
+++ b/cmd/zhack.c
@@ -88,7 +88,7 @@ usage(void)
 
 
 static __attribute__((format(printf, 3, 4))) __attribute__((noreturn)) void
-fatal(spa_t *spa, void *tag, const char *fmt, ...)
+fatal(spa_t *spa, const void *tag, const char *fmt, ...)
 {
 	va_list ap;
 
@@ -166,7 +166,7 @@ zhack_import(char *target, boolean_t readonly)
 }
 
 static void
-zhack_spa_open(char *target, boolean_t readonly, void *tag, spa_t **spa)
+zhack_spa_open(char *target, boolean_t readonly, const void *tag, spa_t **spa)
 {
 	int err;
 
diff --git a/cmd/ztest.c b/cmd/ztest.c
index ff425973a8fe..b7093ce950b9 100644
--- a/cmd/ztest.c
+++ b/cmd/ztest.c
@@ -1537,7 +1537,7 @@ ztest_spa_prop_set_uint64(zpool_prop_t prop, uint64_t value)
 
 static int
 ztest_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 err;
 	char *cp = NULL;
@@ -2810,7 +2810,7 @@ ztest_io(ztest_ds_t *zd, uint64_t object, uint64_t offset)
  * Initialize an object description template.
  */
 static void
-ztest_od_init(ztest_od_t *od, uint64_t id, char *tag, uint64_t index,
+ztest_od_init(ztest_od_t *od, uint64_t id, const char *tag, uint64_t index,
     dmu_object_type_t type, uint64_t blocksize, uint64_t dnodesize,
     uint64_t gen)
 {
diff --git a/include/sys/arc.h b/include/sys/arc.h
index 90b99c6cb1a3..8cee8be4bc93 100644
--- a/include/sys/arc.h
+++ b/include/sys/arc.h
@@ -281,14 +281,14 @@ arc_buf_t *arc_loan_raw_buf(spa_t *spa, 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);
-void arc_return_buf(arc_buf_t *buf, void *tag);
-void arc_loan_inuse_buf(arc_buf_t *buf, void *tag);
-void arc_buf_destroy(arc_buf_t *buf, void *tag);
+void arc_return_buf(arc_buf_t *buf, const void *tag);
+void arc_loan_inuse_buf(arc_buf_t *buf, const void *tag);
+void arc_buf_destroy(arc_buf_t *buf, const void *tag);
 void arc_buf_info(arc_buf_t *buf, arc_buf_info_t *abi, int state_index);
 uint64_t arc_buf_size(arc_buf_t *buf);
 uint64_t arc_buf_lsize(arc_buf_t *buf);
 void arc_buf_access(arc_buf_t *buf);
-void arc_release(arc_buf_t *buf, void *tag);
+void arc_release(arc_buf_t *buf, const void *tag);
 int arc_released(arc_buf_t *buf);
 void arc_buf_sigsegv(int sig, siginfo_t *si, void *unused);
 void arc_buf_freeze(arc_buf_t *buf);
diff --git a/include/sys/dmu.h b/include/sys/dmu.h
index 6bd7a3e9a412..7c55a5c26189 100644
--- a/include/sys/dmu.h
+++ b/include/sys/dmu.h
@@ -573,7 +573,7 @@ int dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset,
  * Add a reference to a dmu buffer that has already been held via
  * dmu_buf_hold() in the current context.
  */
-void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
+void dmu_buf_add_ref(dmu_buf_t *db, const void *tag);
 
 /*
  * Attempt to add a reference to a dmu buffer that is in an unknown state,
diff --git a/include/sys/dsl_bookmark.h b/include/sys/dsl_bookmark.h
index 70f4813449aa..353c5c2d260f 100644
--- a/include/sys/dsl_bookmark.h
+++ b/include/sys/dsl_bookmark.h
@@ -114,7 +114,7 @@ typedef struct dsl_bookmark_create_redacted_arg {
 	redaction_list_t **dbcra_rl;
 	uint64_t	dbcra_numsnaps;
 	uint64_t	*dbcra_snaps;
-	void		*dbcra_tag;
+	const void	*dbcra_tag;
 } dsl_bookmark_create_redacted_arg_t;
 
 int dsl_bookmark_create(nvlist_t *, nvlist_t *);
@@ -122,7 +122,7 @@ int dsl_bookmark_create_nvl_validate(nvlist_t *);
 int dsl_bookmark_create_check(void *arg, dmu_tx_t *tx);
 void dsl_bookmark_create_sync(void *arg, dmu_tx_t *tx);
 int dsl_bookmark_create_redacted(const char *, const char *, uint64_t,
-    uint64_t *, void *, redaction_list_t **);
+    uint64_t *, const void *, redaction_list_t **);
 int dsl_get_bookmarks(const char *, nvlist_t *, nvlist_t *);
 int dsl_get_bookmarks_impl(dsl_dataset_t *, nvlist_t *, nvlist_t *);
 int dsl_get_bookmark_props(const char *, const char *, nvlist_t *);
@@ -131,12 +131,12 @@ int dsl_bookmark_lookup(struct dsl_pool *, const char *,
     struct dsl_dataset *, zfs_bookmark_phys_t *);
 int dsl_bookmark_lookup_impl(dsl_dataset_t *, const char *,
     zfs_bookmark_phys_t *);
-int dsl_redaction_list_hold_obj(struct dsl_pool *, uint64_t, void *,
+int dsl_redaction_list_hold_obj(struct dsl_pool *, uint64_t, const void *,
     redaction_list_t **);
-void dsl_redaction_list_rele(redaction_list_t *, void *);
+void dsl_redaction_list_rele(redaction_list_t *, const void *);
 void dsl_redaction_list_long_hold(struct dsl_pool *, redaction_list_t *,
-    void *);
-void dsl_redaction_list_long_rele(redaction_list_t *, void *);
+    const void *);
+void dsl_redaction_list_long_rele(redaction_list_t *, const void *);
 boolean_t dsl_redaction_list_long_held(redaction_list_t *);
 int dsl_bookmark_init_ds(dsl_dataset_t *);
 void dsl_bookmark_fini_ds(dsl_dataset_t *);
diff --git a/include/sys/dsl_crypt.h b/include/sys/dsl_crypt.h
index 835720c87872..db594eece1c3 100644
--- a/include/sys/dsl_crypt.h
+++ b/include/sys/dsl_crypt.h
@@ -174,19 +174,20 @@ boolean_t dsl_dir_incompatible_encryption_version(dsl_dir_t *dd);
 void spa_keystore_init(spa_keystore_t *sk);
 void spa_keystore_fini(spa_keystore_t *sk);
 
-void spa_keystore_dsl_key_rele(spa_t *spa, dsl_crypto_key_t *dck, void *tag);
+void spa_keystore_dsl_key_rele(spa_t *spa, dsl_crypto_key_t *dck,
+    const void *tag);
 int spa_keystore_load_wkey_impl(spa_t *spa, dsl_wrapping_key_t *wkey);
 int spa_keystore_load_wkey(const char *dsname, dsl_crypto_params_t *dcp,
     boolean_t noop);
 int spa_keystore_unload_wkey_impl(spa_t *spa, uint64_t ddobj);
 int spa_keystore_unload_wkey(const char *dsname);
 
-int spa_keystore_create_mapping(spa_t *spa, struct dsl_dataset *ds, void *tag,
-    dsl_key_mapping_t **km_out);
-int spa_keystore_remove_mapping(spa_t *spa, uint64_t dsobj, void *tag);
-void key_mapping_add_ref(dsl_key_mapping_t *km, void *tag);
-void key_mapping_rele(spa_t *spa, dsl_key_mapping_t *km, void *tag);
-int spa_keystore_lookup_key(spa_t *spa, uint64_t dsobj, void *tag,
+int spa_keystore_create_mapping(spa_t *spa, struct dsl_dataset *ds,
+    const void *tag, dsl_key_mapping_t **km_out);
+int spa_keystore_remove_mapping(spa_t *spa, uint64_t dsobj, const void *tag);
+void key_mapping_add_ref(dsl_key_mapping_t *km, const void *tag);
+void key_mapping_rele(spa_t *spa, dsl_key_mapping_t *km, const void *tag);
+int spa_keystore_lookup_key(spa_t *spa, uint64_t dsobj, const void *tag,
     dsl_crypto_key_t **dck_out);
 
 int dsl_crypto_populate_key_nvlist(struct objset *os,
diff --git a/include/sys/dsl_dir.h b/include/sys/dsl_dir.h
index 993e44354475..6c097e372e44 100644
--- a/include/sys/dsl_dir.h
+++ b/include/sys/dsl_dir.h
@@ -136,12 +136,12 @@ dsl_dir_phys(dsl_dir_t *dd)
 	return (dd->dd_dbuf->db_data);
 }
 
-void dsl_dir_rele(dsl_dir_t *dd, void *tag);
-void dsl_dir_async_rele(dsl_dir_t *dd, void *tag);
-int dsl_dir_hold(dsl_pool_t *dp, const char *name, void *tag,
+void dsl_dir_rele(dsl_dir_t *dd, const void *tag);
+void dsl_dir_async_rele(dsl_dir_t *dd, const void *tag);
+int dsl_dir_hold(dsl_pool_t *dp, const char *name, const void *tag,
     dsl_dir_t **, const char **tail);
 int dsl_dir_hold_obj(dsl_pool_t *dp, uint64_t ddobj,
-    const char *tail, void *tag, dsl_dir_t **);
+    const char *tail, const void *tag, dsl_dir_t **);
 void dsl_dir_name(dsl_dir_t *dd, char *buf);
 int dsl_dir_namelen(dsl_dir_t *dd);
 uint64_t dsl_dir_create_sync(dsl_pool_t *dp, dsl_dir_t *pds,
diff --git a/include/sys/metaslab.h b/include/sys/metaslab.h
index b777a3cae439..140739adb562 100644
--- a/include/sys/metaslab.h
+++ b/include/sys/metaslab.h
@@ -131,9 +131,9 @@ uint64_t metaslab_group_get_space(metaslab_group_t *);
 void metaslab_group_histogram_verify(metaslab_group_t *);
 uint64_t metaslab_group_fragmentation(metaslab_group_t *);
 void metaslab_group_histogram_remove(metaslab_group_t *, metaslab_t *);
-void metaslab_group_alloc_decrement(spa_t *, uint64_t, void *, int, int,
+void metaslab_group_alloc_decrement(spa_t *, uint64_t, const void *, int, int,
     boolean_t);
-void metaslab_group_alloc_verify(spa_t *, const blkptr_t *, void *, int);
+void metaslab_group_alloc_verify(spa_t *, const blkptr_t *, const void *, int);
 void metaslab_recalculate_weight_and_sort(metaslab_t *);
 void metaslab_disable(metaslab_t *);
 void metaslab_enable(metaslab_t *, boolean_t, boolean_t);
diff --git a/include/sys/sa.h b/include/sys/sa.h
index 709018bde612..42479652ab2c 100644
--- a/include/sys/sa.h
+++ b/include/sys/sa.h
@@ -124,8 +124,8 @@ int sa_handle_get(objset_t *, uint64_t, void *userp,
 int sa_handle_get_from_db(objset_t *, dmu_buf_t *, void *userp,
     sa_handle_type_t, sa_handle_t **);
 void sa_handle_destroy(sa_handle_t *);
-int sa_buf_hold(objset_t *, uint64_t, void *, dmu_buf_t **);
-void sa_buf_rele(dmu_buf_t *, void *);
+int sa_buf_hold(objset_t *, uint64_t, const void *, dmu_buf_t **);
+void sa_buf_rele(dmu_buf_t *, const void *);
 int sa_lookup(sa_handle_t *, sa_attr_type_t, void *buf, uint32_t buflen);
 int sa_update(sa_handle_t *, sa_attr_type_t, void *buf,
     uint32_t buflen, dmu_tx_t *);
diff --git a/include/sys/spa.h b/include/sys/spa.h
index 62fad3378e56..cd2499b30b40 100644
--- a/include/sys/spa.h
+++ b/include/sys/spa.h
@@ -982,7 +982,7 @@ extern uint64_t spa_vdev_enter(spa_t *spa);
 extern uint64_t spa_vdev_detach_enter(spa_t *spa, uint64_t guid);
 extern uint64_t spa_vdev_config_enter(spa_t *spa);
 extern void spa_vdev_config_exit(spa_t *spa, vdev_t *vd, uint64_t txg,
-    int error, char *tag);
+    int error, const char *tag);
 extern int spa_vdev_exit(spa_t *spa, vdev_t *vd, uint64_t txg, int error);
 
 /* Pool vdev state change lock */
diff --git a/include/sys/vdev.h b/include/sys/vdev.h
index 4e507d081957..8a526d0bf511 100644
--- a/include/sys/vdev.h
+++ b/include/sys/vdev.h
@@ -104,7 +104,7 @@ extern void vdev_metaslab_fini(vdev_t *vd);
 extern void vdev_metaslab_set_size(vdev_t *);
 extern void vdev_expand(vdev_t *vd, uint64_t txg);
 extern void vdev_split(vdev_t *vd);
-extern void vdev_deadman(vdev_t *vd, char *tag);
+extern void vdev_deadman(vdev_t *vd, const char *tag);
 
 typedef void vdev_xlate_func_t(void *arg, range_seg64_t *physical_rs);
 
diff --git a/include/sys/zap.h b/include/sys/zap.h
index fd7a3a1599bc..dc2f661fb065 100644
--- a/include/sys/zap.h
+++ b/include/sys/zap.h
@@ -139,7 +139,7 @@ uint64_t zap_create_flags_dnsize(objset_t *os, int normflags,
 uint64_t zap_create_hold(objset_t *os, int normflags, zap_flags_t flags,
     dmu_object_type_t ot, int leaf_blockshift, int indirect_blockshift,
     dmu_object_type_t bonustype, int bonuslen, int dnodesize,
-    dnode_t **allocated_dnode, void *tag, dmu_tx_t *tx);
+    dnode_t **allocated_dnode, const void *tag, dmu_tx_t *tx);
 
 uint64_t zap_create_link(objset_t *os, dmu_object_type_t ot,
     uint64_t parent_obj, const char *name, dmu_tx_t *tx);
diff --git a/include/sys/zap_impl.h b/include/sys/zap_impl.h
index 250dde3ce235..4549a9bd1177 100644
--- a/include/sys/zap_impl.h
+++ b/include/sys/zap_impl.h
@@ -199,8 +199,9 @@ typedef struct zap_name {
 
 boolean_t zap_match(zap_name_t *zn, const char *matchname);
 int zap_lockdir(objset_t *os, uint64_t obj, dmu_tx_t *tx,
-    krw_t lti, boolean_t fatreader, boolean_t adding, void *tag, zap_t **zapp);
-void zap_unlockdir(zap_t *zap, void *tag);
+    krw_t lti, boolean_t fatreader, boolean_t adding, const void *tag,
+    zap_t **zapp);
+void zap_unlockdir(zap_t *zap, const void *tag);
 void zap_evict_sync(void *dbu);
 zap_name_t *zap_name_alloc(zap_t *zap, const char *key, matchtype_t mt);
 void zap_name_free(zap_name_t *zn);
@@ -217,10 +218,10 @@ int fzap_lookup(zap_name_t *zn,
     char *realname, int rn_len, boolean_t *normalization_conflictp);
 void fzap_prefetch(zap_name_t *zn);
 int fzap_add(zap_name_t *zn, uint64_t integer_size, uint64_t num_integers,
-    const void *val, void *tag, dmu_tx_t *tx);
+    const void *val, const void *tag, dmu_tx_t *tx);
 int fzap_update(zap_name_t *zn,
     int integer_size, uint64_t num_integers, const void *val,
-    void *tag, dmu_tx_t *tx);
+    const void *tag, dmu_tx_t *tx);
 int fzap_length(zap_name_t *zn,
     uint64_t *integer_size, uint64_t *num_integers);
 int fzap_remove(zap_name_t *zn, dmu_tx_t *tx);
@@ -230,7 +231,7 @@ void zap_put_leaf(struct zap_leaf *l);
 
 int fzap_add_cd(zap_name_t *zn,
     uint64_t integer_size, uint64_t num_integers,
-    const void *val, uint32_t cd, void *tag, dmu_tx_t *tx);
+    const void *val, uint32_t cd, const void *tag, dmu_tx_t *tx);
 void fzap_upgrade(zap_t *zap, dmu_tx_t *tx, zap_flags_t flags);
 
 #ifdef	__cplusplus
diff --git a/include/sys/zcp.h b/include/sys/zcp.h
index d7b1dfaa2ea5..f0a78f9cb5c4 100644
--- a/include/sys/zcp.h
+++ b/include/sys/zcp.h
@@ -177,7 +177,7 @@ void zcp_parse_args(lua_State *, const char *, const zcp_arg_t *,
 int zcp_nvlist_to_lua(lua_State *, nvlist_t *, char *, int);
 int zcp_dataset_hold_error(lua_State *, dsl_pool_t *, const char *, int);
 struct dsl_dataset *zcp_dataset_hold(lua_State *, dsl_pool_t *,
-    const char *, void *);
+    const char *, const void *);
 
 typedef int (zcp_lib_func_t)(lua_State *);
 typedef struct zcp_lib_info {
diff --git a/include/sys/zio.h b/include/sys/zio.h
index 4b624165f8b3..9bee7cc9b9fd 100644
--- a/include/sys/zio.h
+++ b/include/sys/zio.h
@@ -589,7 +589,7 @@ extern void zio_execute(void *zio);
 extern void zio_interrupt(void *zio);
 extern void zio_delay_init(zio_t *zio);
 extern void zio_delay_interrupt(zio_t *zio);
-extern void zio_deadman(zio_t *zio, char *tag);
+extern void zio_deadman(zio_t *zio, const char *tag);
 
 extern zio_t *zio_walk_parents(zio_t *cio, zio_link_t **);
 extern zio_t *zio_walk_children(zio_t *pio, zio_link_t **);
@@ -657,7 +657,8 @@ extern int zio_inject_fault(char *name, int flags, int *id,
 extern int zio_inject_list_next(int *id, char *name, size_t buflen,
     struct zinject_record *record);
 extern int zio_clear_fault(int id);
-extern void zio_handle_panic_injection(spa_t *spa, char *tag, uint64_t type);
+extern void zio_handle_panic_injection(spa_t *spa, const char *tag,
+    uint64_t type);
 extern int zio_handle_decrypt_injection(spa_t *spa, const zbookmark_phys_t *zb,
     uint64_t type, int error);
 extern int zio_handle_fault_injection(zio_t *zio, int error);
diff --git a/module/os/freebsd/zfs/zfs_znode.c b/module/os/freebsd/zfs/zfs_znode.c
index 84cff13f0dfe..6115ac7a566e 100644
--- a/module/os/freebsd/zfs/zfs_znode.c
+++ b/module/os/freebsd/zfs/zfs_znode.c
@@ -1814,7 +1814,7 @@ zfs_sa_setup(objset_t *osp, sa_attr_type_t **sa_table)
 
 static int
 zfs_grab_sa_handle(objset_t *osp, uint64_t obj, sa_handle_t **hdlp,
-    dmu_buf_t **db, void *tag)
+    dmu_buf_t **db, const void *tag)
 {
 	dmu_object_info_t doi;
 	int error;
@@ -1841,7 +1841,7 @@ zfs_grab_sa_handle(objset_t *osp, uint64_t obj, sa_handle_t **hdlp,
 }
 
 static void
-zfs_release_sa_handle(sa_handle_t *hdl, dmu_buf_t *db, void *tag)
+zfs_release_sa_handle(sa_handle_t *hdl, dmu_buf_t *db, const void *tag)
 {
 	sa_handle_destroy(hdl);
 	sa_buf_rele(db, tag);
diff --git a/module/os/linux/zfs/zfs_znode.c b/module/os/linux/zfs/zfs_znode.c
index d921f2b07463..dc504b1a120b 100644
--- a/module/os/linux/zfs/zfs_znode.c
+++ b/module/os/linux/zfs/zfs_znode.c
@@ -2001,7 +2001,7 @@ zfs_sa_setup(objset_t *osp, sa_attr_type_t **sa_table)
 
 static int
 zfs_grab_sa_handle(objset_t *osp, uint64_t obj, sa_handle_t **hdlp,
-    dmu_buf_t **db, void *tag)
+    dmu_buf_t **db, const void *tag)
 {
 	dmu_object_info_t doi;
 	int error;
@@ -2028,7 +2028,7 @@ zfs_grab_sa_handle(objset_t *osp, uint64_t obj, sa_handle_t **hdlp,
 }
 
 static void
-zfs_release_sa_handle(sa_handle_t *hdl, dmu_buf_t *db, void *tag)
+zfs_release_sa_handle(sa_handle_t *hdl, dmu_buf_t *db, const void *tag)
 {
 	sa_handle_destroy(hdl);
 	sa_buf_rele(db, tag);
diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index 919081c255ce..74019ad08b4c 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -848,12 +848,13 @@ enum arc_hdr_alloc_flags {
 };
 
 
-static abd_t *arc_get_data_abd(arc_buf_hdr_t *, uint64_t, void *, int);
-static void *arc_get_data_buf(arc_buf_hdr_t *, uint64_t, void *);
-static void arc_get_data_impl(arc_buf_hdr_t *, uint64_t, void *, int);
-static void arc_free_data_abd(arc_buf_hdr_t *, abd_t *, uint64_t, void *);
-static void arc_free_data_buf(arc_buf_hdr_t *, void *, uint64_t, void *);
-static void arc_free_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag);
+static abd_t *arc_get_data_abd(arc_buf_hdr_t *, uint64_t, const void *, int);
+static void *arc_get_data_buf(arc_buf_hdr_t *, uint64_t, const void *);
+static void arc_get_data_impl(arc_buf_hdr_t *, uint64_t, const void *, int);
+static void arc_free_data_abd(arc_buf_hdr_t *, abd_t *, uint64_t, const void *);
+static void arc_free_data_buf(arc_buf_hdr_t *, void *, uint64_t, const void *);
+static void arc_free_data_impl(arc_buf_hdr_t *hdr, uint64_t size,
+    const void *tag);
 static void arc_hdr_free_abd(arc_buf_hdr_t *, boolean_t);
 static void arc_hdr_alloc_abd(arc_buf_hdr_t *, int);
 static void arc_access(arc_buf_hdr_t *, kmutex_t *);
@@ -2316,7 +2317,7 @@ add_reference(arc_buf_hdr_t *hdr, const void *tag)
  * list making it eligible for eviction.
  */
 static int
-remove_reference(arc_buf_hdr_t *hdr, kmutex_t *hash_lock, void *tag)
+remove_reference(arc_buf_hdr_t *hdr, kmutex_t *hash_lock, const void *tag)
 {
 	int cnt;
 	arc_state_t *state = hdr->b_l1hdr.b_state;
@@ -2900,7 +2901,7 @@ arc_loan_raw_buf(spa_t *spa, uint64_t dsobj, boolean_t byteorder,
  * Return a loaned arc buffer to the arc.
  */
 void
-arc_return_buf(arc_buf_t *buf, void *tag)
+arc_return_buf(arc_buf_t *buf, const void *tag)
 {
 	arc_buf_hdr_t *hdr = buf->b_hdr;
 
@@ -2914,7 +2915,7 @@ arc_return_buf(arc_buf_t *buf, void *tag)
 
 /* Detach an arc_buf from a dbuf (tag) */
 void
-arc_loan_inuse_buf(arc_buf_t *buf, void *tag)
+arc_loan_inuse_buf(arc_buf_t *buf, const void *tag)
 {
 	arc_buf_hdr_t *hdr = buf->b_hdr;
 
@@ -3845,7 +3846,7 @@ arc_hdr_destroy(arc_buf_hdr_t *hdr)
 }
 
 void
-arc_buf_destroy(arc_buf_t *buf, void* tag)
+arc_buf_destroy(arc_buf_t *buf, const void *tag)
 {
 	arc_buf_hdr_t *hdr = buf->b_hdr;
 
@@ -5208,7 +5209,7 @@ arc_is_overflowing(boolean_t use_reserve)
 }
 
 static abd_t *
-arc_get_data_abd(arc_buf_hdr_t *hdr, uint64_t size, void *tag,
+arc_get_data_abd(arc_buf_hdr_t *hdr, uint64_t size, const void *tag,
     int alloc_flags)
 {
 	arc_buf_contents_t type = arc_buf_type(hdr);
@@ -5223,7 +5224,7 @@ arc_get_data_abd(arc_buf_hdr_t *hdr, uint64_t size, void *tag,
 }
 
 static void *
-arc_get_data_buf(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
+arc_get_data_buf(arc_buf_hdr_t *hdr, uint64_t size, const void *tag)
 {
 	arc_buf_contents_t type = arc_buf_type(hdr);
 
@@ -5322,7 +5323,7 @@ arc_wait_for_eviction(uint64_t amount, boolean_t use_reserve)
  * limit, we'll only signal the reclaim thread and continue on.
  */
 static void
-arc_get_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag,
+arc_get_data_impl(arc_buf_hdr_t *hdr, uint64_t size, const void *tag,
     int alloc_flags)
 {
 	arc_state_t *state = hdr->b_l1hdr.b_state;
@@ -5390,14 +5391,15 @@ arc_get_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag,
 }
 
 static void
-arc_free_data_abd(arc_buf_hdr_t *hdr, abd_t *abd, uint64_t size, void *tag)
+arc_free_data_abd(arc_buf_hdr_t *hdr, abd_t *abd, uint64_t size,
+    const void *tag)
 {
 	arc_free_data_impl(hdr, size, tag);
 	abd_free(abd);
 }
 
 static void
-arc_free_data_buf(arc_buf_hdr_t *hdr, void *buf, uint64_t size, void *tag)
+arc_free_data_buf(arc_buf_hdr_t *hdr, void *buf, uint64_t size, const void *tag)
 {
 	arc_buf_contents_t type = arc_buf_type(hdr);
 
@@ -5414,7 +5416,7 @@ arc_free_data_buf(arc_buf_hdr_t *hdr, void *buf, uint64_t size, void *tag)
  * Free the arc data buffer.
  */
 static void
-arc_free_data_impl(arc_buf_hdr_t *hdr, uint64_t size, void *tag)
+arc_free_data_impl(arc_buf_hdr_t *hdr, uint64_t size, const void *tag)
 {
 	arc_state_t *state = hdr->b_l1hdr.b_state;
 	arc_buf_contents_t type = arc_buf_type(hdr);
@@ -6576,7 +6578,7 @@ arc_freed(spa_t *spa, const blkptr_t *bp)
  * a new hdr for the buffer.
  */
 void
-arc_release(arc_buf_t *buf, void *tag)
+arc_release(arc_buf_t *buf, const void *tag)
 {
 	arc_buf_hdr_t *hdr = buf->b_hdr;
 
diff --git a/module/zfs/dmu_redact.c b/module/zfs/dmu_redact.c
index 9b0fe8a747d8..ae2e65d5c4b8 100644
--- a/module/zfs/dmu_redact.c
+++ b/module/zfs/dmu_redact.c
@@ -855,7 +855,7 @@ redact_merge_thread(void *arg)
  * object number.
  */
 static int
-hold_next_object(objset_t *os, struct redact_record *rec, void *tag,
+hold_next_object(objset_t *os, struct redact_record *rec, const void *tag,
     uint64_t *object, dnode_t **dn)
 {
 	int err = 0;
diff --git a/module/zfs/dmu_send.c b/module/zfs/dmu_send.c
index ab385ae30dc8..ca0163891c07 100644
--- a/module/zfs/dmu_send.c
+++ b/module/zfs/dmu_send.c
@@ -1917,7 +1917,7 @@ send_reader_thread(void *arg)
 
 struct dmu_send_params {
 	/* Pool args */
-	void *tag; // Tag that dp was held with, will be used to release dp.
+	const void *tag; // Tag dp was held with, will be used to release dp.
 	dsl_pool_t *dp;
 	/* To snapshot args */
 	const char *tosnap;
@@ -2366,7 +2366,7 @@ dmu_send_impl(struct dmu_send_params *dspp)
 	dsl_dataset_t *to_ds = dspp->to_ds;
 	zfs_bookmark_phys_t *ancestor_zb = &dspp->ancestor_zb;
 	dsl_pool_t *dp = dspp->dp;
-	void *tag = dspp->tag;
+	const void *tag = dspp->tag;
 
 	err = dmu_objset_from_ds(to_ds, &os);
 	if (err != 0) {
diff --git a/module/zfs/dsl_bookmark.c b/module/zfs/dsl_bookmark.c
index 4e44b167fb14..8ca7ba8957aa 100644
--- a/module/zfs/dsl_bookmark.c
+++ b/module/zfs/dsl_bookmark.c
@@ -37,7 +37,7 @@
 
 static int
 dsl_bookmark_hold_ds(dsl_pool_t *dp, const char *fullname,
-    dsl_dataset_t **dsp, void *tag, char **shortnamep)
+    dsl_dataset_t **dsp, const void *tag, char **shortnamep)
 {
 	char buf[ZFS_MAX_DATASET_NAME_LEN];
 	char *hashp;
@@ -438,8 +438,8 @@ dsl_bookmark_node_add(dsl_dataset_t *hds, dsl_bookmark_node_t *dbn,
  */
 static void
 dsl_bookmark_create_sync_impl_snap(const char *bookmark, const char *snapshot,
-    dmu_tx_t *tx, uint64_t num_redact_snaps, uint64_t *redact_snaps, void *tag,
-    redaction_list_t **redaction_list)
+    dmu_tx_t *tx, uint64_t num_redact_snaps, uint64_t *redact_snaps,
+    const void *tag, redaction_list_t **redaction_list)
 {
 	dsl_pool_t *dp = dmu_tx_pool(tx);
 	objset_t *mos = dp->dp_meta_objset;
@@ -664,7 +664,8 @@ dsl_bookmark_create_redacted_sync(void *arg, dmu_tx_t *tx)
 
 int
 dsl_bookmark_create_redacted(const char *bookmark, const char *snapshot,
-    uint64_t numsnaps, uint64_t *snapguids, void *tag, redaction_list_t **rl)
+    uint64_t numsnaps, uint64_t *snapguids, const void *tag,
+    redaction_list_t **rl)
 {
 	dsl_bookmark_create_redacted_arg_t dbcra;
 
@@ -1188,14 +1189,15 @@ dsl_redaction_list_long_held(redaction_list_t *rl)
 }
 
 void
-dsl_redaction_list_long_hold(dsl_pool_t *dp, redaction_list_t *rl, void *tag)
+dsl_redaction_list_long_hold(dsl_pool_t *dp, redaction_list_t *rl,
+    const void *tag)
 {
 	ASSERT(dsl_pool_config_held(dp));
 	(void) zfs_refcount_add(&rl->rl_longholds, tag);
 }
 
 void
-dsl_redaction_list_long_rele(redaction_list_t *rl, void *tag)
+dsl_redaction_list_long_rele(redaction_list_t *rl, const void *tag)
 {
 	(void) zfs_refcount_remove(&rl->rl_longholds, tag);
 }
@@ -1210,13 +1212,13 @@ redaction_list_evict_sync(void *rlu)
 }
 
 void
-dsl_redaction_list_rele(redaction_list_t *rl, void *tag)
+dsl_redaction_list_rele(redaction_list_t *rl, const void *tag)
 {
 	dmu_buf_rele(rl->rl_dbuf, tag);
 }
 
 int
-dsl_redaction_list_hold_obj(dsl_pool_t *dp, uint64_t rlobj, void *tag,
+dsl_redaction_list_hold_obj(dsl_pool_t *dp, uint64_t rlobj, const void *tag,
     redaction_list_t **rlp)
 {
 	objset_t *mos = dp->dp_meta_objset;
diff --git a/module/zfs/dsl_crypt.c b/module/zfs/dsl_crypt.c
index 44e0083d2f26..25cb4f6ab1ad 100644
--- a/module/zfs/dsl_crypt.c
+++ b/module/zfs/dsl_crypt.c
@@ -80,13 +80,13 @@
 int zfs_disable_ivset_guid_check = 0;
 
 static void
-dsl_wrapping_key_hold(dsl_wrapping_key_t *wkey, void *tag)
+dsl_wrapping_key_hold(dsl_wrapping_key_t *wkey, const void *tag)
 {
 	(void) zfs_refcount_add(&wkey->wk_refcnt, tag);
 }
 
 static void
-dsl_wrapping_key_rele(dsl_wrapping_key_t *wkey, void *tag)
+dsl_wrapping_key_rele(dsl_wrapping_key_t *wkey, const void *tag)
 {
 	(void) zfs_refcount_remove(&wkey->wk_refcnt, tag);
 }
@@ -368,7 +368,7 @@ dsl_dir_incompatible_encryption_version(dsl_dir_t *dd)
 
 static int
 spa_keystore_wkey_hold_ddobj_impl(spa_t *spa, uint64_t ddobj,
-    void *tag, dsl_wrapping_key_t **wkey_out)
+    const void *tag, dsl_wrapping_key_t **wkey_out)
 {
 	int ret;
 	dsl_wrapping_key_t search_wkey;
@@ -398,7 +398,7 @@ error:
 }
 
 static int
-spa_keystore_wkey_hold_dd(spa_t *spa, dsl_dir_t *dd, void *tag,
+spa_keystore_wkey_hold_dd(spa_t *spa, dsl_dir_t *dd, const void *tag,
     dsl_wrapping_key_t **wkey_out)
 {
 	int ret;
@@ -514,7 +514,7 @@ dsl_crypto_key_free(dsl_crypto_key_t *dck)
 }
 
 static void
-dsl_crypto_key_rele(dsl_crypto_key_t *dck, void *tag)
+dsl_crypto_key_rele(dsl_crypto_key_t *dck, const void *tag)
 {
 	if (zfs_refcount_remove(&dck->dck_holds, tag) == 0)
 		dsl_crypto_key_free(dck);
@@ -522,7 +522,7 @@ dsl_crypto_key_rele(dsl_crypto_key_t *dck, void *tag)
 
 static int
 dsl_crypto_key_open(objset_t *mos, dsl_wrapping_key_t *wkey,
-    uint64_t dckobj, void *tag, dsl_crypto_key_t **dck_out)
+    uint64_t dckobj, const void *tag, dsl_crypto_key_t **dck_out)
 {
 	int ret;
 	uint64_t crypt = 0, guid = 0, version = 0;
@@ -600,7 +600,7 @@ error:
 }
 
 static int
-spa_keystore_dsl_key_hold_impl(spa_t *spa, uint64_t dckobj, void *tag,
+spa_keystore_dsl_key_hold_impl(spa_t *spa, uint64_t dckobj, const void *tag,
     dsl_crypto_key_t **dck_out)
 {
 	int ret;
@@ -631,7 +631,7 @@ error:
 }
 
 static int
-spa_keystore_dsl_key_hold_dd(spa_t *spa, dsl_dir_t *dd, void *tag,
+spa_keystore_dsl_key_hold_dd(spa_t *spa, dsl_dir_t *dd, const void *tag,
     dsl_crypto_key_t **dck_out)
 {
 	int ret;
@@ -689,7 +689,7 @@ spa_keystore_dsl_key_hold_dd(spa_t *spa, dsl_dir_t *dd, void *tag,
 }
 
 void
-spa_keystore_dsl_key_rele(spa_t *spa, dsl_crypto_key_t *dck, void *tag)
+spa_keystore_dsl_key_rele(spa_t *spa, dsl_crypto_key_t *dck, const void *tag)
 {
 	rw_enter(&spa->spa_keystore.sk_dk_lock, RW_WRITER);
 
@@ -936,7 +936,7 @@ error:
 }
 
 void
-key_mapping_add_ref(dsl_key_mapping_t *km, void *tag)
+key_mapping_add_ref(dsl_key_mapping_t *km, const void *tag)
 {
 	ASSERT3U(zfs_refcount_count(&km->km_refcnt), >=, 1);
 	zfs_refcount_add(&km->km_refcnt, tag);
@@ -953,7 +953,7 @@ key_mapping_add_ref(dsl_key_mapping_t *km, void *tag)
  * mapping after unmounting a dataset.
  */
 void
-key_mapping_rele(spa_t *spa, dsl_key_mapping_t *km, void *tag)
+key_mapping_rele(spa_t *spa, dsl_key_mapping_t *km, const void *tag)
 {
 	ASSERT3U(zfs_refcount_count(&km->km_refcnt), >=, 1);
 
@@ -984,7 +984,7 @@ key_mapping_rele(spa_t *spa, dsl_key_mapping_t *km, void *tag)
 }
 
 int
-spa_keystore_create_mapping(spa_t *spa, dsl_dataset_t *ds, void *tag,
+spa_keystore_create_mapping(spa_t *spa, dsl_dataset_t *ds, const void *tag,
     dsl_key_mapping_t **km_out)
 {
 	int ret;
@@ -1043,7 +1043,7 @@ spa_keystore_create_mapping(spa_t *spa, dsl_dataset_t *ds, void *tag,
 }
 
 int
-spa_keystore_remove_mapping(spa_t *spa, uint64_t dsobj, void *tag)
+spa_keystore_remove_mapping(spa_t *spa, uint64_t dsobj, const void *tag)
 {
 	int ret;
 	dsl_key_mapping_t search_km;
@@ -1081,7 +1081,7 @@ error_unlock:
  * without getting a reference to it.
  */
 int
-spa_keystore_lookup_key(spa_t *spa, uint64_t dsobj, void *tag,
+spa_keystore_lookup_key(spa_t *spa, uint64_t dsobj, const void *tag,
     dsl_crypto_key_t **dck_out)
 {
 	int ret;
diff --git a/module/zfs/dsl_destroy.c b/module/zfs/dsl_destroy.c
index 7dddd8eed5e9..f44de67f4693 100644
--- a/module/zfs/dsl_destroy.c
+++ b/module/zfs/dsl_destroy.c
@@ -200,7 +200,7 @@ rck_alloc(dsl_dataset_t *clone)
 
 static void
 dsl_dir_remove_clones_key_impl(dsl_dir_t *dd, uint64_t mintxg, dmu_tx_t *tx,
-    list_t *stack, void *tag)
+    list_t *stack, const void *tag)
 {
 	objset_t *mos = dd->dd_pool->dp_meta_objset;
 
diff --git a/module/zfs/dsl_dir.c b/module/zfs/dsl_dir.c
index 252dd2912523..b5f50c9bde1d 100644
--- a/module/zfs/dsl_dir.c
+++ b/module/zfs/dsl_dir.c
@@ -160,7 +160,7 @@ dsl_dir_evict_async(void *dbu)
 
 int
 dsl_dir_hold_obj(dsl_pool_t *dp, uint64_t ddobj,
-    const char *tail, void *tag, dsl_dir_t **ddp)
+    const char *tail, const void *tag, dsl_dir_t **ddp)
 {
 	dmu_buf_t *dbuf;
 	dsl_dir_t *dd;
@@ -320,7 +320,7 @@ errout:
 }
 
 void
-dsl_dir_rele(dsl_dir_t *dd, void *tag)
+dsl_dir_rele(dsl_dir_t *dd, const void *tag)
 {
 	dprintf_dd(dd, "%s\n", "");
 	spa_close(dd->dd_pool->dp_spa, tag);
@@ -335,7 +335,7 @@ dsl_dir_rele(dsl_dir_t *dd, void *tag)
  * the spa.
  */
 void
-dsl_dir_async_rele(dsl_dir_t *dd, void *tag)
+dsl_dir_async_rele(dsl_dir_t *dd, const void *tag)
 {
 	dprintf_dd(dd, "%s\n", "");
 	spa_async_close(dd->dd_pool->dp_spa, tag);
@@ -449,7 +449,7 @@ getcomponent(const char *path, char *component, const char **nextp)
  * (*tail)[0] == '@' means that the last component is a snapshot.
  */
 int
-dsl_dir_hold(dsl_pool_t *dp, const char *name, void *tag,
+dsl_dir_hold(dsl_pool_t *dp, const char *name, const void *tag,
     dsl_dir_t **ddp, const char **tailp)
 {
 	char *buf;
diff --git a/module/zfs/dsl_scan.c b/module/zfs/dsl_scan.c
index 4303492e42f0..e8b581390c07 100644
--- a/module/zfs/dsl_scan.c
+++ b/module/zfs/dsl_scan.c
@@ -1505,7 +1505,7 @@ scan_prefetch_queue_compare(const void *a, const void *b)
 }
 
 static void
-scan_prefetch_ctx_rele(scan_prefetch_ctx_t *spc, void *tag)
+scan_prefetch_ctx_rele(scan_prefetch_ctx_t *spc, const void *tag)
 {
 	if (zfs_refcount_remove(&spc->spc_refcnt, tag) == 0) {
 		zfs_refcount_destroy(&spc->spc_refcnt);
@@ -1514,7 +1514,7 @@ scan_prefetch_ctx_rele(scan_prefetch_ctx_t *spc, void *tag)
 }
 
 static scan_prefetch_ctx_t *
-scan_prefetch_ctx_create(dsl_scan_t *scn, dnode_phys_t *dnp, void *tag)
+scan_prefetch_ctx_create(dsl_scan_t *scn, dnode_phys_t *dnp, const void *tag)
 {
 	scan_prefetch_ctx_t *spc;
 
@@ -1536,7 +1536,7 @@ scan_prefetch_ctx_create(dsl_scan_t *scn, dnode_phys_t *dnp, void *tag)
 }
 
 static void
-scan_prefetch_ctx_add_ref(scan_prefetch_ctx_t *spc, void *tag)
+scan_prefetch_ctx_add_ref(scan_prefetch_ctx_t *spc, const void *tag)
 {
 	zfs_refcount_add(&spc->spc_refcnt, tag);
 }
diff --git a/module/zfs/metaslab.c b/module/zfs/metaslab.c
index ab32bfec1310..444ab5222b3b 100644
--- a/module/zfs/metaslab.c
+++ b/module/zfs/metaslab.c
@@ -4508,8 +4508,8 @@ metaslab_trace_fini(zio_alloc_list_t *zal)
  */
 
 static void
-metaslab_group_alloc_increment(spa_t *spa, uint64_t vdev, void *tag, int flags,
-    int allocator)
+metaslab_group_alloc_increment(spa_t *spa, uint64_t vdev, const void *tag,
+    int flags, int allocator)
 {
 	if (!(flags & METASLAB_ASYNC_ALLOC) ||
 	    (flags & METASLAB_DONT_THROTTLE))
@@ -4542,8 +4542,8 @@ metaslab_group_increment_qdepth(metaslab_group_t *mg, int allocator)
 }
 
 void
-metaslab_group_alloc_decrement(spa_t *spa, uint64_t vdev, void *tag, int flags,
-    int allocator, boolean_t io_complete)
+metaslab_group_alloc_decrement(spa_t *spa, uint64_t vdev, const void *tag,
+    int flags, int allocator, boolean_t io_complete)
 {
 	if (!(flags & METASLAB_ASYNC_ALLOC) ||
 	    (flags & METASLAB_DONT_THROTTLE))
@@ -4560,7 +4560,7 @@ metaslab_group_alloc_decrement(spa_t *spa, uint64_t vdev, void *tag, int flags,
 }
 
 void
-metaslab_group_alloc_verify(spa_t *spa, const blkptr_t *bp, void *tag,
+metaslab_group_alloc_verify(spa_t *spa, const blkptr_t *bp, const void *tag,
     int allocator)
 {
 #ifdef ZFS_DEBUG
diff --git a/module/zfs/sa.c b/module/zfs/sa.c
index db8c2b831f1d..368a9e3d9080 100644
--- a/module/zfs/sa.c
+++ b/module/zfs/sa.c
@@ -1449,13 +1449,13 @@ sa_handle_get(objset_t *objset, uint64_t objid, void *userp,
 }
 
 int
-sa_buf_hold(objset_t *objset, uint64_t obj_num, void *tag, dmu_buf_t **db)
+sa_buf_hold(objset_t *objset, uint64_t obj_num, const void *tag, dmu_buf_t **db)
 {
 	return (dmu_bonus_hold(objset, obj_num, tag, db));
 }
 
 void
-sa_buf_rele(dmu_buf_t *db, void *tag)
+sa_buf_rele(dmu_buf_t *db, const void *tag)
 {
 	dmu_buf_rele(db, tag);
 }
diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c
index aaca2a8a58d6..2ae45e169ebe 100644
--- a/module/zfs/spa_misc.c
+++ b/module/zfs/spa_misc.c
@@ -1215,7 +1215,8 @@ spa_vdev_config_enter(spa_t *spa)
  * of multiple transactions without releasing the spa_namespace_lock.
  */
 void
-spa_vdev_config_exit(spa_t *spa, vdev_t *vd, uint64_t txg, int error, char *tag)
+spa_vdev_config_exit(spa_t *spa, vdev_t *vd, uint64_t txg, int error,
+    const char *tag)
 {
 	ASSERT(MUTEX_HELD(&spa_namespace_lock));
 
diff --git a/module/zfs/space_map.c b/module/zfs/space_map.c
index 61282f693c2c..1aa20a96711e 100644
--- a/module/zfs/space_map.c
+++ b/module/zfs/space_map.c
@@ -549,7 +549,7 @@ space_map_write_intro_debug(space_map_t *sm, maptype_t maptype, dmu_tx_t *tx)
 static void
 space_map_write_seg(space_map_t *sm, uint64_t rstart, uint64_t rend,
     maptype_t maptype, uint64_t vdev_id, uint8_t words, dmu_buf_t **dbp,
-    void *tag, dmu_tx_t *tx)
+    const void *tag, dmu_tx_t *tx)
 {
 	ASSERT3U(words, !=, 0);
 	ASSERT3U(words, <=, 2);
diff --git a/module/zfs/vdev.c b/module/zfs/vdev.c
index dedbc1a23e33..de29e6fd4c7c 100644
--- a/module/zfs/vdev.c
+++ b/module/zfs/vdev.c
@@ -5233,7 +5233,7 @@ vdev_split(vdev_t *vd)
 }
 
 void
-vdev_deadman(vdev_t *vd, char *tag)
+vdev_deadman(vdev_t *vd, const char *tag)
 {
 	for (int c = 0; c < vd->vdev_children; c++) {
 		vdev_t *cvd = vd->vdev_child[c];
diff --git a/module/zfs/zap.c b/module/zfs/zap.c
index b2b9dc27f1b6..d533f17cca9f 100644
--- a/module/zfs/zap.c
+++ b/module/zfs/zap.c
@@ -626,7 +626,7 @@ zap_deref_leaf(zap_t *zap, uint64_t h, dmu_tx_t *tx, krw_t lt, zap_leaf_t **lp)
 
 static int
 zap_expand_leaf(zap_name_t *zn, zap_leaf_t *l,
-    void *tag, dmu_tx_t *tx, zap_leaf_t **lp)
+    const void *tag, dmu_tx_t *tx, zap_leaf_t **lp)
 {
 	zap_t *zap = zn->zn_zap;
 	uint64_t hash = zn->zn_hash;
@@ -715,7 +715,7 @@ zap_expand_leaf(zap_name_t *zn, zap_leaf_t *l,
 
 static void
 zap_put_leaf_maybe_grow_ptrtbl(zap_name_t *zn, zap_leaf_t *l,
-    void *tag, dmu_tx_t *tx)
+    const void *tag, dmu_tx_t *tx)
 {
 	zap_t *zap = zn->zn_zap;
 	int shift = zap_f_phys(zap)->zap_ptrtbl.zt_shift;
@@ -824,7 +824,7 @@ fzap_lookup(zap_name_t *zn,
 int
 fzap_add_cd(zap_name_t *zn,
     uint64_t integer_size, uint64_t num_integers,
-    const void *val, uint32_t cd, void *tag, dmu_tx_t *tx)
+    const void *val, uint32_t cd, const void *tag, dmu_tx_t *tx)
 {
 	zap_leaf_t *l;
 	int err;
@@ -876,7 +876,7 @@ out:
 int
 fzap_add(zap_name_t *zn,
     uint64_t integer_size, uint64_t num_integers,
-    const void *val, void *tag, dmu_tx_t *tx)
+    const void *val, const void *tag, dmu_tx_t *tx)
 {
 	int err = fzap_check(zn, integer_size, num_integers);
 	if (err != 0)
@@ -889,7 +889,7 @@ fzap_add(zap_name_t *zn,
 int
 fzap_update(zap_name_t *zn,
     int integer_size, uint64_t num_integers, const void *val,
-    void *tag, dmu_tx_t *tx)
+    const void *tag, dmu_tx_t *tx)
 {
 	zap_leaf_t *l;
 	int err;
diff --git a/module/zfs/zap_micro.c b/module/zfs/zap_micro.c
index 85134e999bea..09780a6c5989 100644
--- a/module/zfs/zap_micro.c
+++ b/module/zfs/zap_micro.c
@@ -42,7 +42,7 @@
 #endif
 
 static int mzap_upgrade(zap_t **zapp,
-    void *tag, dmu_tx_t *tx, zap_flags_t flags);
+    const void *tag, dmu_tx_t *tx, zap_flags_t flags);
 
 uint64_t
 zap_getflags(zap_t *zap)
@@ -503,7 +503,7 @@ handle_winner:
  * have the specified tag.
  */
 static int
-zap_lockdir_impl(dmu_buf_t *db, void *tag, dmu_tx_t *tx,
+zap_lockdir_impl(dmu_buf_t *db, const void *tag, dmu_tx_t *tx,
     krw_t lti, boolean_t fatreader, boolean_t adding, zap_t **zapp)
 {
 	ASSERT0(db->db_offset);
@@ -579,7 +579,8 @@ zap_lockdir_impl(dmu_buf_t *db, void *tag, dmu_tx_t *tx,
 
 static int
 zap_lockdir_by_dnode(dnode_t *dn, dmu_tx_t *tx,
-    krw_t lti, boolean_t fatreader, boolean_t adding, void *tag, zap_t **zapp)
+    krw_t lti, boolean_t fatreader, boolean_t adding, const void *tag,
+    zap_t **zapp)
 {
 	dmu_buf_t *db;
 
@@ -604,7 +605,8 @@ zap_lockdir_by_dnode(dnode_t *dn, dmu_tx_t *tx,
 
 int
 zap_lockdir(objset_t *os, uint64_t obj, dmu_tx_t *tx,
-    krw_t lti, boolean_t fatreader, boolean_t adding, void *tag, zap_t **zapp)
+    krw_t lti, boolean_t fatreader, boolean_t adding, const void *tag,
+    zap_t **zapp)
 {
 	dmu_buf_t *db;
 
@@ -625,14 +627,14 @@ zap_lockdir(objset_t *os, uint64_t obj, dmu_tx_t *tx,
 }
 
 void
-zap_unlockdir(zap_t *zap, void *tag)
+zap_unlockdir(zap_t *zap, const void *tag)
 {
 	rw_exit(&zap->zap_rwlock);
 	dmu_buf_rele(zap->zap_dbuf, tag);
 }
 
 static int
-mzap_upgrade(zap_t **zapp, void *tag, dmu_tx_t *tx, zap_flags_t flags)
+mzap_upgrade(zap_t **zapp, const void *tag, dmu_tx_t *tx, zap_flags_t flags)
 {
 	int err = 0;
 	zap_t *zap = *zapp;
@@ -725,7 +727,7 @@ static uint64_t
 zap_create_impl(objset_t *os, int normflags, zap_flags_t flags,
     dmu_object_type_t ot, int leaf_blockshift, int indirect_blockshift,
     dmu_object_type_t bonustype, int bonuslen, int dnodesize,
-    dnode_t **allocated_dnode, void *tag, dmu_tx_t *tx)
+    dnode_t **allocated_dnode, const void *tag, dmu_tx_t *tx)
 {
 	uint64_t obj;
 
@@ -857,7 +859,7 @@ uint64_t
 zap_create_hold(objset_t *os, int normflags, zap_flags_t flags,
     dmu_object_type_t ot, int leaf_blockshift, int indirect_blockshift,
     dmu_object_type_t bonustype, int bonuslen, int dnodesize,
-    dnode_t **allocated_dnode, void *tag, dmu_tx_t *tx)
+    dnode_t **allocated_dnode, const void *tag, dmu_tx_t *tx)
 {
 	return (zap_create_impl(os, normflags, flags, ot, leaf_blockshift,
 	    indirect_blockshift, bonustype, bonuslen, dnodesize,
@@ -1222,7 +1224,7 @@ again:
 static int
 zap_add_impl(zap_t *zap, const char *key,
     int integer_size, uint64_t num_integers,
-    const void *val, dmu_tx_t *tx, void *tag)
+    const void *val, dmu_tx_t *tx, const void *tag)
 {
 	const uint64_t *intval = val;
 	int err = 0;
diff --git a/module/zfs/zcp.c b/module/zfs/zcp.c
index dcfb55d3b3c4..fe90242ca40d 100644
--- a/module/zfs/zcp.c
+++ b/module/zfs/zcp.c
@@ -622,7 +622,7 @@ zcp_dataset_hold_error(lua_State *state, dsl_pool_t *dp, const char *dsname,
  */
 dsl_dataset_t *
 zcp_dataset_hold(lua_State *state, dsl_pool_t *dp, const char *dsname,
-    void *tag)
+    const void *tag)
 {
 	dsl_dataset_t *ds;
 	int error = dsl_dataset_hold(dp, dsname, tag, &ds);
diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index 35aec5226233..3b71dcb0e788 100644
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -1397,7 +1397,8 @@ getzfsvfs(const char *dsname, zfsvfs_t **zfvp)
  * which prevents all inode ops from running.
  */
 static int
-zfsvfs_hold(const char *name, void *tag, zfsvfs_t **zfvp, boolean_t writer)
+zfsvfs_hold(const char *name, const void *tag, zfsvfs_t **zfvp,
+    boolean_t writer)
 {
 	int error = 0;
 
@@ -1422,7 +1423,7 @@ zfsvfs_hold(const char *name, void *tag, zfsvfs_t **zfvp, boolean_t writer)
 }
 
 static void
-zfsvfs_rele(zfsvfs_t *zfsvfs, void *tag)
+zfsvfs_rele(zfsvfs_t *zfsvfs, const void *tag)
 {
 	ZFS_TEARDOWN_EXIT(zfsvfs, tag);
 
diff --git a/module/zfs/zio.c b/module/zfs/zio.c
index ae99f1e6450d..1c9f598b7d13 100644
--- a/module/zfs/zio.c
+++ b/module/zfs/zio.c
@@ -2062,7 +2062,7 @@ zio_deadman_impl(zio_t *pio, int ziodepth)
  * using the zfs_dbgmsg() interface then post deadman event for the ZED.
  */
 void
-zio_deadman(zio_t *pio, char *tag)
+zio_deadman(zio_t *pio, const char *tag)
 {
 	spa_t *spa = pio->io_spa;
 	char *name = spa_name(spa);
diff --git a/module/zfs/zio_inject.c b/module/zfs/zio_inject.c
index 9b629ca0f1f9..f10abaf17209 100644
--- a/module/zfs/zio_inject.c
+++ b/module/zfs/zio_inject.c
@@ -162,7 +162,7 @@ zio_match_handler(const zbookmark_phys_t *zb, uint64_t type, int dva,
  * specified by tag.
  */
 void
-zio_handle_panic_injection(spa_t *spa, char *tag, uint64_t type)
+zio_handle_panic_injection(spa_t *spa, const char *tag, uint64_t type)
 {
 	inject_handler_t *handler;