[mirror_zfs.git] / module / zfs / refcount.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or https://opensource.org/licenses/CDDL-1.0.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2012, 2021 by Delphix. All rights reserved.
 */

#include <sys/zfs_context.h>
#include <sys/zfs_refcount.h>

#ifdef	ZFS_DEBUG
/*
 * Reference count tracking is disabled by default.  It's memory requirements
 * are reasonable, however as implemented it consumes a significant amount of
 * cpu time.  Until its performance is improved it should be manually enabled.
 */
int reference_tracking_enable = B_FALSE;
static uint_t reference_history = 3; /* tunable */

static kmem_cache_t *reference_cache;
static kmem_cache_t *reference_history_cache;

void
zfs_refcount_init(void)
{
	reference_cache = kmem_cache_create("reference_cache",
	    sizeof (reference_t), 0, NULL, NULL, NULL, NULL, NULL, 0);

	reference_history_cache = kmem_cache_create("reference_history_cache",
	    sizeof (uint64_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
}

void
zfs_refcount_fini(void)
{
	kmem_cache_destroy(reference_cache);
	kmem_cache_destroy(reference_history_cache);
}

void
zfs_refcount_create(zfs_refcount_t *rc)
{
	mutex_init(&rc->rc_mtx, NULL, MUTEX_DEFAULT, NULL);
	list_create(&rc->rc_list, sizeof (reference_t),
	    offsetof(reference_t, ref_link));
	list_create(&rc->rc_removed, sizeof (reference_t),
	    offsetof(reference_t, ref_link));
	rc->rc_count = 0;
	rc->rc_removed_count = 0;
	rc->rc_tracked = reference_tracking_enable;
}

void
zfs_refcount_create_tracked(zfs_refcount_t *rc)
{
	zfs_refcount_create(rc);
	rc->rc_tracked = B_TRUE;
}

void
zfs_refcount_create_untracked(zfs_refcount_t *rc)
{
	zfs_refcount_create(rc);
	rc->rc_tracked = B_FALSE;
}

void
zfs_refcount_destroy_many(zfs_refcount_t *rc, uint64_t number)
{
	reference_t *ref;

	ASSERT3U(rc->rc_count, ==, number);
	while ((ref = list_head(&rc->rc_list))) {
		list_remove(&rc->rc_list, ref);
		kmem_cache_free(reference_cache, ref);
	}
	list_destroy(&rc->rc_list);

	while ((ref = list_head(&rc->rc_removed))) {
		list_remove(&rc->rc_removed, ref);
		kmem_cache_free(reference_history_cache, ref->ref_removed);
		kmem_cache_free(reference_cache, ref);
	}
	list_destroy(&rc->rc_removed);
	mutex_destroy(&rc->rc_mtx);
}

void
zfs_refcount_destroy(zfs_refcount_t *rc)
{
	zfs_refcount_destroy_many(rc, 0);
}

int
zfs_refcount_is_zero(zfs_refcount_t *rc)
{
	return (zfs_refcount_count(rc) == 0);
}

int64_t
zfs_refcount_count(zfs_refcount_t *rc)
{
	return (atomic_load_64(&rc->rc_count));
}

int64_t
zfs_refcount_add_many(zfs_refcount_t *rc, uint64_t number, const void *holder)
{
	reference_t *ref = NULL;
	int64_t count;

	if (!rc->rc_tracked) {
		count = atomic_add_64_nv(&(rc)->rc_count, number);
		ASSERT3U(count, >=, number);
		return (count);
	}

	ref = kmem_cache_alloc(reference_cache, KM_SLEEP);
	ref->ref_holder = holder;
	ref->ref_number = number;
	mutex_enter(&rc->rc_mtx);
	list_insert_head(&rc->rc_list, ref);
	rc->rc_count += number;
	count = rc->rc_count;
	mutex_exit(&rc->rc_mtx);

	return (count);
}

int64_t
zfs_refcount_add(zfs_refcount_t *rc, const void *holder)
{
	return (zfs_refcount_add_many(rc, 1, holder));
}

int64_t
zfs_refcount_remove_many(zfs_refcount_t *rc, uint64_t number,
    const void *holder)
{
	reference_t *ref;
	int64_t count;

	if (!rc->rc_tracked) {
		count = atomic_add_64_nv(&(rc)->rc_count, -number);
		ASSERT3S(count, >=, 0);
		return (count);
	}

	mutex_enter(&rc->rc_mtx);
	ASSERT3U(rc->rc_count, >=, number);
	for (ref = list_head(&rc->rc_list); ref;
	    ref = list_next(&rc->rc_list, ref)) {
		if (ref->ref_holder == holder && ref->ref_number == number) {
			list_remove(&rc->rc_list, ref);
			if (reference_history > 0) {
				ref->ref_removed =
				    kmem_cache_alloc(reference_history_cache,
				    KM_SLEEP);
				list_insert_head(&rc->rc_removed, ref);
				rc->rc_removed_count++;
				if (rc->rc_removed_count > reference_history) {
					ref = list_tail(&rc->rc_removed);
					list_remove(&rc->rc_removed, ref);
					kmem_cache_free(reference_history_cache,
					    ref->ref_removed);
					kmem_cache_free(reference_cache, ref);
					rc->rc_removed_count--;
				}
			} else {
				kmem_cache_free(reference_cache, ref);
			}
			rc->rc_count -= number;
			count = rc->rc_count;
			mutex_exit(&rc->rc_mtx);
			return (count);
		}
	}
	panic("No such hold %p on refcount %llx", holder,
	    (u_longlong_t)(uintptr_t)rc);
	return (-1);
}

int64_t
zfs_refcount_remove(zfs_refcount_t *rc, const void *holder)
{
	return (zfs_refcount_remove_many(rc, 1, holder));
}

void
zfs_refcount_transfer(zfs_refcount_t *dst, zfs_refcount_t *src)
{
	int64_t count, removed_count;
	list_t list, removed;

	list_create(&list, sizeof (reference_t),
	    offsetof(reference_t, ref_link));
	list_create(&removed, sizeof (reference_t),
	    offsetof(reference_t, ref_link));

	mutex_enter(&src->rc_mtx);
	count = src->rc_count;
	removed_count = src->rc_removed_count;
	src->rc_count = 0;
	src->rc_removed_count = 0;
	list_move_tail(&list, &src->rc_list);
	list_move_tail(&removed, &src->rc_removed);
	mutex_exit(&src->rc_mtx);

	mutex_enter(&dst->rc_mtx);
	dst->rc_count += count;
	dst->rc_removed_count += removed_count;
	list_move_tail(&dst->rc_list, &list);
	list_move_tail(&dst->rc_removed, &removed);
	mutex_exit(&dst->rc_mtx);

	list_destroy(&list);
	list_destroy(&removed);
}

void
zfs_refcount_transfer_ownership_many(zfs_refcount_t *rc, uint64_t number,
    const void *current_holder, const void *new_holder)
{
	reference_t *ref;
	boolean_t found = B_FALSE;

	if (!rc->rc_tracked)
		return;

	mutex_enter(&rc->rc_mtx);
	for (ref = list_head(&rc->rc_list); ref;
	    ref = list_next(&rc->rc_list, ref)) {
		if (ref->ref_holder == current_holder &&
		    ref->ref_number == number) {
			ref->ref_holder = new_holder;
			found = B_TRUE;
			break;
		}
	}
	ASSERT(found);
	mutex_exit(&rc->rc_mtx);
}

void
zfs_refcount_transfer_ownership(zfs_refcount_t *rc, const void *current_holder,
    const void *new_holder)
{
	return (zfs_refcount_transfer_ownership_many(rc, 1, current_holder,
	    new_holder));
}

/*
 * If tracking is enabled, return true if a reference exists that matches
 * the "holder" tag. If tracking is disabled, then return true if a reference
 * might be held.
 */
boolean_t
zfs_refcount_held(zfs_refcount_t *rc, const void *holder)
{
	reference_t *ref;

	if (!rc->rc_tracked)
		return (zfs_refcount_count(rc) > 0);

	mutex_enter(&rc->rc_mtx);
	for (ref = list_head(&rc->rc_list); ref;
	    ref = list_next(&rc->rc_list, ref)) {
		if (ref->ref_holder == holder) {
			mutex_exit(&rc->rc_mtx);
			return (B_TRUE);
		}
	}
	mutex_exit(&rc->rc_mtx);
	return (B_FALSE);
}

/*
 * If tracking is enabled, return true if a reference does not exist that
 * matches the "holder" tag. If tracking is disabled, always return true
 * since the reference might not be held.
 */
boolean_t
zfs_refcount_not_held(zfs_refcount_t *rc, const void *holder)
{
	reference_t *ref;

	if (!rc->rc_tracked)
		return (B_TRUE);

	mutex_enter(&rc->rc_mtx);
	for (ref = list_head(&rc->rc_list); ref;
	    ref = list_next(&rc->rc_list, ref)) {
		if (ref->ref_holder == holder) {
			mutex_exit(&rc->rc_mtx);
			return (B_FALSE);
		}
	}
	mutex_exit(&rc->rc_mtx);
	return (B_TRUE);
}

EXPORT_SYMBOL(zfs_refcount_create);
EXPORT_SYMBOL(zfs_refcount_destroy);
EXPORT_SYMBOL(zfs_refcount_is_zero);
EXPORT_SYMBOL(zfs_refcount_count);
EXPORT_SYMBOL(zfs_refcount_add);
EXPORT_SYMBOL(zfs_refcount_remove);
EXPORT_SYMBOL(zfs_refcount_held);

/* BEGIN CSTYLED */
ZFS_MODULE_PARAM(zfs, , reference_tracking_enable, INT, ZMOD_RW,
	"Track reference holders to refcount_t objects");

ZFS_MODULE_PARAM(zfs, , reference_history, UINT, ZMOD_RW,
	"Maximum reference holders being tracked");
/* END CSTYLED */
#endif	/* ZFS_DEBUG */
Commit	Line	Data
34dc7c2f BB	1	/*
	2	* CDDL HEADER START
	3	*
	4	* The contents of this file are subject to the terms of the
	5	* Common Development and Distribution License (the "License").
	6	* You may not use this file except in compliance with the License.
	7	*
	8	* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
1d3ba0bf	9	* or https://opensource.org/licenses/CDDL-1.0.
34dc7c2f BB	10	* See the License for the specific language governing permissions
	11	* and limitations under the License.
	12	*
	13	* When distributing Covered Code, include this CDDL HEADER in each
	14	* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
	15	* If applicable, add the following below this CDDL HEADER, with the
	16	* fields enclosed by brackets "[]" replaced with your own identifying
	17	* information: Portions Copyright [yyyy] [name of copyright owner]
	18	*
	19	* CDDL HEADER END
	20	*/
	21	/*
428870ff	22	* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
dd0b5c85	23	* Copyright (c) 2012, 2021 by Delphix. All rights reserved.
34dc7c2f BB	24	*/
34dc7c2f BB	25
34dc7c2f	26	#include <sys/zfs_context.h>
27d96d22	27	#include <sys/zfs_refcount.h>
34dc7c2f	28
18168da7	29	#ifdef ZFS_DEBUG
791e480c BB	30	/*
	31	* Reference count tracking is disabled by default. It's memory requirements
	32	* are reasonable, however as implemented it consumes a significant amount of
	33	* cpu time. Until its performance is improved it should be manually enabled.
	34	*/
18168da7	35	int reference_tracking_enable = B_FALSE;
fdc2d303	36	static uint_t reference_history = 3; /* tunable */
34dc7c2f BB	37
	38	static kmem_cache_t *reference_cache;
	39	static kmem_cache_t *reference_history_cache;
	40
	41	void
424fd7c3	42	zfs_refcount_init(void)
34dc7c2f BB	43	{
	44	reference_cache = kmem_cache_create("reference_cache",
	45	sizeof (reference_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
	46
	47	reference_history_cache = kmem_cache_create("reference_history_cache",
	48	sizeof (uint64_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
	49	}
	50
	51	void
424fd7c3	52	zfs_refcount_fini(void)
34dc7c2f BB	53	{
	54	kmem_cache_destroy(reference_cache);
	55	kmem_cache_destroy(reference_history_cache);
	56	}
	57
	58	void
424fd7c3	59	zfs_refcount_create(zfs_refcount_t *rc)
34dc7c2f BB	60	{
	61	mutex_init(&rc->rc_mtx, NULL, MUTEX_DEFAULT, NULL);
	62	list_create(&rc->rc_list, sizeof (reference_t),
	63	offsetof(reference_t, ref_link));
	64	list_create(&rc->rc_removed, sizeof (reference_t),
	65	offsetof(reference_t, ref_link));
	66	rc->rc_count = 0;
	67	rc->rc_removed_count = 0;
13fe0198 MA	68	rc->rc_tracked = reference_tracking_enable;
	69	}
	70
3dfb57a3	71	void
424fd7c3	72	zfs_refcount_create_tracked(zfs_refcount_t *rc)
3dfb57a3	73	{
424fd7c3	74	zfs_refcount_create(rc);
3dfb57a3 DB	75	rc->rc_tracked = B_TRUE;
	76	}
	77
13fe0198	78	void
424fd7c3	79	zfs_refcount_create_untracked(zfs_refcount_t *rc)
13fe0198	80	{
424fd7c3	81	zfs_refcount_create(rc);
13fe0198	82	rc->rc_tracked = B_FALSE;
34dc7c2f BB	83	}
	84
	85	void
424fd7c3	86	zfs_refcount_destroy_many(zfs_refcount_t *rc, uint64_t number)
34dc7c2f BB	87	{
	88	reference_t *ref;
	89
30af21b0	90	ASSERT3U(rc->rc_count, ==, number);
c65aa5b2	91	while ((ref = list_head(&rc->rc_list))) {
34dc7c2f BB	92	list_remove(&rc->rc_list, ref);
	93	kmem_cache_free(reference_cache, ref);
	94	}
	95	list_destroy(&rc->rc_list);
	96
c65aa5b2	97	while ((ref = list_head(&rc->rc_removed))) {
34dc7c2f BB	98	list_remove(&rc->rc_removed, ref);
	99	kmem_cache_free(reference_history_cache, ref->ref_removed);
	100	kmem_cache_free(reference_cache, ref);
	101	}
	102	list_destroy(&rc->rc_removed);
	103	mutex_destroy(&rc->rc_mtx);
	104	}
	105
	106	void
424fd7c3	107	zfs_refcount_destroy(zfs_refcount_t *rc)
34dc7c2f	108	{
424fd7c3	109	zfs_refcount_destroy_many(rc, 0);
34dc7c2f BB	110	}
	111
	112	int
424fd7c3	113	zfs_refcount_is_zero(zfs_refcount_t *rc)
34dc7c2f	114	{
e829a865	115	return (zfs_refcount_count(rc) == 0);
34dc7c2f BB	116	}
	117
	118	int64_t
424fd7c3	119	zfs_refcount_count(zfs_refcount_t *rc)
34dc7c2f	120	{
e829a865	121	return (atomic_load_64(&rc->rc_count));
34dc7c2f BB	122	}
	123
	124	int64_t
dc04a8c7	125	zfs_refcount_add_many(zfs_refcount_t rc, uint64_t number, const void holder)
34dc7c2f	126	{
d4ed6673	127	reference_t *ref = NULL;
34dc7c2f BB	128	int64_t count;
34dc7c2f BB	129
e829a865 AM	130	if (!rc->rc_tracked) {
	131	count = atomic_add_64_nv(&(rc)->rc_count, number);
	132	ASSERT3U(count, >=, number);
	133	return (count);
34dc7c2f	134	}
e829a865 AM	135
	136	ref = kmem_cache_alloc(reference_cache, KM_SLEEP);
	137	ref->ref_holder = holder;
	138	ref->ref_number = number;
34dc7c2f	139	mutex_enter(&rc->rc_mtx);
e829a865	140	list_insert_head(&rc->rc_list, ref);
34dc7c2f BB	141	rc->rc_count += number;
	142	count = rc->rc_count;
	143	mutex_exit(&rc->rc_mtx);
	144
	145	return (count);
	146	}
	147
	148	int64_t
dc04a8c7	149	zfs_refcount_add(zfs_refcount_t rc, const void holder)
34dc7c2f	150	{
424fd7c3	151	return (zfs_refcount_add_many(rc, 1, holder));
34dc7c2f BB	152	}
	153
	154	int64_t
dc04a8c7 PD	155	zfs_refcount_remove_many(zfs_refcount_t *rc, uint64_t number,
dc04a8c7 PD	156	const void *holder)
34dc7c2f BB	157	{
	158	reference_t *ref;
	159	int64_t count;
	160
13fe0198	161	if (!rc->rc_tracked) {
e829a865 AM	162	count = atomic_add_64_nv(&(rc)->rc_count, -number);
e829a865 AM	163	ASSERT3S(count, >=, 0);
34dc7c2f BB	164	return (count);
	165	}
	166
e829a865 AM	167	mutex_enter(&rc->rc_mtx);
e829a865 AM	168	ASSERT3U(rc->rc_count, >=, number);
34dc7c2f BB	169	for (ref = list_head(&rc->rc_list); ref;
	170	ref = list_next(&rc->rc_list, ref)) {
	171	if (ref->ref_holder == holder && ref->ref_number == number) {
	172	list_remove(&rc->rc_list, ref);
	173	if (reference_history > 0) {
	174	ref->ref_removed =
	175	kmem_cache_alloc(reference_history_cache,
79c76d5b	176	KM_SLEEP);
34dc7c2f BB	177	list_insert_head(&rc->rc_removed, ref);
34dc7c2f BB	178	rc->rc_removed_count++;
13fe0198	179	if (rc->rc_removed_count > reference_history) {
34dc7c2f BB	180	ref = list_tail(&rc->rc_removed);
	181	list_remove(&rc->rc_removed, ref);
	182	kmem_cache_free(reference_history_cache,
	183	ref->ref_removed);
	184	kmem_cache_free(reference_cache, ref);
	185	rc->rc_removed_count--;
	186	}
	187	} else {
	188	kmem_cache_free(reference_cache, ref);
	189	}
	190	rc->rc_count -= number;
	191	count = rc->rc_count;
	192	mutex_exit(&rc->rc_mtx);
	193	return (count);
	194	}
	195	}
	196	panic("No such hold %p on refcount %llx", holder,
	197	(u_longlong_t)(uintptr_t)rc);
	198	return (-1);
	199	}
	200
	201	int64_t
dc04a8c7	202	zfs_refcount_remove(zfs_refcount_t rc, const void holder)
34dc7c2f	203	{
424fd7c3	204	return (zfs_refcount_remove_many(rc, 1, holder));
34dc7c2f BB	205	}
34dc7c2f BB	206
572e2857	207	void
424fd7c3	208	zfs_refcount_transfer(zfs_refcount_t dst, zfs_refcount_t src)
572e2857 BB	209	{
	210	int64_t count, removed_count;
	211	list_t list, removed;
	212
	213	list_create(&list, sizeof (reference_t),
	214	offsetof(reference_t, ref_link));
	215	list_create(&removed, sizeof (reference_t),
	216	offsetof(reference_t, ref_link));
	217
	218	mutex_enter(&src->rc_mtx);
	219	count = src->rc_count;
	220	removed_count = src->rc_removed_count;
	221	src->rc_count = 0;
	222	src->rc_removed_count = 0;
	223	list_move_tail(&list, &src->rc_list);
	224	list_move_tail(&removed, &src->rc_removed);
	225	mutex_exit(&src->rc_mtx);
	226
	227	mutex_enter(&dst->rc_mtx);
	228	dst->rc_count += count;
	229	dst->rc_removed_count += removed_count;
	230	list_move_tail(&dst->rc_list, &list);
	231	list_move_tail(&dst->rc_removed, &removed);
	232	mutex_exit(&dst->rc_mtx);
	233
	234	list_destroy(&list);
	235	list_destroy(&removed);
	236	}
	237
d3c2ae1c	238	void
d7e4b30a	239	zfs_refcount_transfer_ownership_many(zfs_refcount_t *rc, uint64_t number,
dc04a8c7	240	const void current_holder, const void new_holder)
d3c2ae1c GW	241	{
	242	reference_t *ref;
	243	boolean_t found = B_FALSE;
	244
e829a865	245	if (!rc->rc_tracked)
d3c2ae1c	246	return;
d3c2ae1c	247
e829a865	248	mutex_enter(&rc->rc_mtx);
d3c2ae1c GW	249	for (ref = list_head(&rc->rc_list); ref;
d3c2ae1c GW	250	ref = list_next(&rc->rc_list, ref)) {
d7e4b30a BB	251	if (ref->ref_holder == current_holder &&
d7e4b30a BB	252	ref->ref_number == number) {
d3c2ae1c GW	253	ref->ref_holder = new_holder;
	254	found = B_TRUE;
	255	break;
	256	}
	257	}
	258	ASSERT(found);
	259	mutex_exit(&rc->rc_mtx);
	260	}
3dfb57a3	261
d7e4b30a	262	void
dc04a8c7 PD	263	zfs_refcount_transfer_ownership(zfs_refcount_t rc, const void current_holder,
dc04a8c7 PD	264	const void *new_holder)
d7e4b30a BB	265	{
	266	return (zfs_refcount_transfer_ownership_many(rc, 1, current_holder,
	267	new_holder));
	268	}
	269
3dfb57a3 DB	270	/*
	271	* If tracking is enabled, return true if a reference exists that matches
	272	* the "holder" tag. If tracking is disabled, then return true if a reference
	273	* might be held.
	274	*/
	275	boolean_t
dc04a8c7	276	zfs_refcount_held(zfs_refcount_t rc, const void holder)
3dfb57a3 DB	277	{
	278	reference_t *ref;
	279
e829a865 AM	280	if (!rc->rc_tracked)
e829a865 AM	281	return (zfs_refcount_count(rc) > 0);
3dfb57a3	282
e829a865	283	mutex_enter(&rc->rc_mtx);
3dfb57a3 DB	284	for (ref = list_head(&rc->rc_list); ref;
	285	ref = list_next(&rc->rc_list, ref)) {
	286	if (ref->ref_holder == holder) {
	287	mutex_exit(&rc->rc_mtx);
	288	return (B_TRUE);
	289	}
	290	}
	291	mutex_exit(&rc->rc_mtx);
	292	return (B_FALSE);
	293	}
	294
	295	/*
	296	* If tracking is enabled, return true if a reference does not exist that
	297	* matches the "holder" tag. If tracking is disabled, always return true
	298	* since the reference might not be held.
	299	*/
	300	boolean_t
dc04a8c7	301	zfs_refcount_not_held(zfs_refcount_t rc, const void holder)
3dfb57a3 DB	302	{
	303	reference_t *ref;
	304
e829a865	305	if (!rc->rc_tracked)
3dfb57a3	306	return (B_TRUE);
3dfb57a3	307
e829a865	308	mutex_enter(&rc->rc_mtx);
3dfb57a3 DB	309	for (ref = list_head(&rc->rc_list); ref;
	310	ref = list_next(&rc->rc_list, ref)) {
	311	if (ref->ref_holder == holder) {
	312	mutex_exit(&rc->rc_mtx);
	313	return (B_FALSE);
	314	}
	315	}
	316	mutex_exit(&rc->rc_mtx);
	317	return (B_TRUE);
	318	}
dd0b5c85	319
280d0f0c BB	320	EXPORT_SYMBOL(zfs_refcount_create);
	321	EXPORT_SYMBOL(zfs_refcount_destroy);
	322	EXPORT_SYMBOL(zfs_refcount_is_zero);
	323	EXPORT_SYMBOL(zfs_refcount_count);
	324	EXPORT_SYMBOL(zfs_refcount_add);
	325	EXPORT_SYMBOL(zfs_refcount_remove);
	326	EXPORT_SYMBOL(zfs_refcount_held);
	327
dd0b5c85	328	/* BEGIN CSTYLED */
18168da7	329	ZFS_MODULE_PARAM(zfs, , reference_tracking_enable, INT, ZMOD_RW,
dd0b5c85 DB	330	"Track reference holders to refcount_t objects");
dd0b5c85 DB	331
fdc2d303	332	ZFS_MODULE_PARAM(zfs, , reference_history, UINT, ZMOD_RW,
dd0b5c85 DB	333	"Maximum reference holders being tracked");
dd0b5c85 DB	334	/* END CSTYLED */
572e2857	335	#endif /* ZFS_DEBUG */