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/*
* 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 http://www.opensolaris.org/os/licensing.
* 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.
*/
#include <sys/zfs_context.h>
#include <sys/refcount.h>
#ifdef ZFS_DEBUG
#ifdef _KERNEL
int reference_tracking_enable = FALSE; /* runs out of memory too easily */
#else
int reference_tracking_enable = TRUE;
#endif
int reference_history = 4; /* tunable */
static kmem_cache_t *reference_cache;
static kmem_cache_t *reference_history_cache;
void
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
refcount_fini(void)
{
kmem_cache_destroy(reference_cache);
kmem_cache_destroy(reference_history_cache);
}
void
refcount_create(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;
}
void
refcount_destroy_many(refcount_t *rc, uint64_t number)
{
reference_t *ref;
ASSERT(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
refcount_destroy(refcount_t *rc)
{
refcount_destroy_many(rc, 0);
}
int
refcount_is_zero(refcount_t *rc)
{
ASSERT(rc->rc_count >= 0);
return (rc->rc_count == 0);
}
int64_t
refcount_count(refcount_t *rc)
{
ASSERT(rc->rc_count >= 0);
return (rc->rc_count);
}
int64_t
refcount_add_many(refcount_t *rc, uint64_t number, void *holder)
{
reference_t *ref = NULL;
int64_t count;
if (reference_tracking_enable) {
ref = kmem_cache_alloc(reference_cache, KM_PUSHPAGE);
ref->ref_holder = holder;
ref->ref_number = number;
}
mutex_enter(&rc->rc_mtx);
ASSERT(rc->rc_count >= 0);
if (reference_tracking_enable)
list_insert_head(&rc->rc_list, ref);
rc->rc_count += number;
count = rc->rc_count;
mutex_exit(&rc->rc_mtx);
return (count);
}
int64_t
refcount_add(refcount_t *rc, void *holder)
{
return (refcount_add_many(rc, 1, holder));
}
int64_t
refcount_remove_many(refcount_t *rc, uint64_t number, void *holder)
{
reference_t *ref;
int64_t count;
mutex_enter(&rc->rc_mtx);
ASSERT(rc->rc_count >= number);
if (!reference_tracking_enable) {
rc->rc_count -= number;
count = rc->rc_count;
mutex_exit(&rc->rc_mtx);
return (count);
}
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_PUSHPAGE);
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
refcount_remove(refcount_t *rc, void *holder)
{
return (refcount_remove_many(rc, 1, holder));
}
void
refcount_transfer(refcount_t *dst, 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);
}
#endif /* ZFS_DEBUG */
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