refcount.c revision 277492
1168404Spjd/* 2168404Spjd * CDDL HEADER START 3168404Spjd * 4168404Spjd * The contents of this file are subject to the terms of the 5185029Spjd * Common Development and Distribution License (the "License"). 6185029Spjd * You may not use this file except in compliance with the License. 7168404Spjd * 8168404Spjd * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9168404Spjd * or http://www.opensolaris.org/os/licensing. 10168404Spjd * See the License for the specific language governing permissions 11168404Spjd * and limitations under the License. 12168404Spjd * 13168404Spjd * When distributing Covered Code, include this CDDL HEADER in each 14168404Spjd * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15168404Spjd * If applicable, add the following below this CDDL HEADER, with the 16168404Spjd * fields enclosed by brackets "[]" replaced with your own identifying 17168404Spjd * information: Portions Copyright [yyyy] [name of copyright owner] 18168404Spjd * 19168404Spjd * CDDL HEADER END 20168404Spjd */ 21168404Spjd/* 22219089Spjd * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. 23248571Smm * Copyright (c) 2012 by Delphix. All rights reserved. 24168404Spjd */ 25168404Spjd 26168404Spjd#include <sys/zfs_context.h> 27168404Spjd#include <sys/refcount.h> 28168404Spjd 29219089Spjd#ifdef ZFS_DEBUG 30168404Spjd 31168404Spjd#ifdef _KERNEL 32168404Spjdint reference_tracking_enable = FALSE; /* runs out of memory too easily */ 33277492SwillSYSCTL_DECL(_vfs_zfs); 34277492SwillSYSCTL_INT(_vfs_zfs, OID_AUTO, reference_tracking_enable, CTLFLAG_RDTUN, 35277492Swill &reference_tracking_enable, 0, 36277492Swill "Track reference holders to refcount_t objects, used mostly by ZFS"); 37168404Spjd#else 38168404Spjdint reference_tracking_enable = TRUE; 39168404Spjd#endif 40248571Smmint reference_history = 3; /* tunable */ 41168404Spjd 42168404Spjdstatic kmem_cache_t *reference_cache; 43168404Spjdstatic kmem_cache_t *reference_history_cache; 44168404Spjd 45168404Spjdvoid 46179310Spjdrefcount_sysinit(void) 47168404Spjd{ 48168404Spjd reference_cache = kmem_cache_create("reference_cache", 49168404Spjd sizeof (reference_t), 0, NULL, NULL, NULL, NULL, NULL, 0); 50168404Spjd 51168404Spjd reference_history_cache = kmem_cache_create("reference_history_cache", 52168404Spjd sizeof (uint64_t), 0, NULL, NULL, NULL, NULL, NULL, 0); 53168404Spjd} 54168404Spjd 55168404Spjdvoid 56168404Spjdrefcount_fini(void) 57168404Spjd{ 58168404Spjd kmem_cache_destroy(reference_cache); 59168404Spjd kmem_cache_destroy(reference_history_cache); 60168404Spjd} 61168404Spjd 62168404Spjdvoid 63168404Spjdrefcount_create(refcount_t *rc) 64168404Spjd{ 65185029Spjd mutex_init(&rc->rc_mtx, NULL, MUTEX_DEFAULT, NULL); 66168404Spjd list_create(&rc->rc_list, sizeof (reference_t), 67168404Spjd offsetof(reference_t, ref_link)); 68168404Spjd list_create(&rc->rc_removed, sizeof (reference_t), 69168404Spjd offsetof(reference_t, ref_link)); 70185029Spjd rc->rc_count = 0; 71185029Spjd rc->rc_removed_count = 0; 72248571Smm rc->rc_tracked = reference_tracking_enable; 73168404Spjd} 74168404Spjd 75168404Spjdvoid 76248571Smmrefcount_create_untracked(refcount_t *rc) 77248571Smm{ 78248571Smm refcount_create(rc); 79248571Smm rc->rc_tracked = B_FALSE; 80248571Smm} 81248571Smm 82248571Smmvoid 83168404Spjdrefcount_destroy_many(refcount_t *rc, uint64_t number) 84168404Spjd{ 85168404Spjd reference_t *ref; 86168404Spjd 87168404Spjd ASSERT(rc->rc_count == number); 88168404Spjd while (ref = list_head(&rc->rc_list)) { 89168404Spjd list_remove(&rc->rc_list, ref); 90168404Spjd kmem_cache_free(reference_cache, ref); 91168404Spjd } 92168404Spjd list_destroy(&rc->rc_list); 93168404Spjd 94168404Spjd while (ref = list_head(&rc->rc_removed)) { 95168404Spjd list_remove(&rc->rc_removed, ref); 96168404Spjd kmem_cache_free(reference_history_cache, ref->ref_removed); 97168404Spjd kmem_cache_free(reference_cache, ref); 98168404Spjd } 99168404Spjd list_destroy(&rc->rc_removed); 100168404Spjd mutex_destroy(&rc->rc_mtx); 101168404Spjd} 102168404Spjd 103168404Spjdvoid 104168404Spjdrefcount_destroy(refcount_t *rc) 105168404Spjd{ 106168404Spjd refcount_destroy_many(rc, 0); 107168404Spjd} 108168404Spjd 109168404Spjdint 110168404Spjdrefcount_is_zero(refcount_t *rc) 111168404Spjd{ 112168404Spjd return (rc->rc_count == 0); 113168404Spjd} 114168404Spjd 115168404Spjdint64_t 116168404Spjdrefcount_count(refcount_t *rc) 117168404Spjd{ 118168404Spjd return (rc->rc_count); 119168404Spjd} 120168404Spjd 121168404Spjdint64_t 122168404Spjdrefcount_add_many(refcount_t *rc, uint64_t number, void *holder) 123168404Spjd{ 124247187Smm reference_t *ref = NULL; 125168404Spjd int64_t count; 126168404Spjd 127248571Smm if (rc->rc_tracked) { 128168404Spjd ref = kmem_cache_alloc(reference_cache, KM_SLEEP); 129168404Spjd ref->ref_holder = holder; 130168404Spjd ref->ref_number = number; 131168404Spjd } 132168404Spjd mutex_enter(&rc->rc_mtx); 133168404Spjd ASSERT(rc->rc_count >= 0); 134248571Smm if (rc->rc_tracked) 135168404Spjd list_insert_head(&rc->rc_list, ref); 136168404Spjd rc->rc_count += number; 137168404Spjd count = rc->rc_count; 138168404Spjd mutex_exit(&rc->rc_mtx); 139168404Spjd 140168404Spjd return (count); 141168404Spjd} 142168404Spjd 143168404Spjdint64_t 144168404Spjdrefcount_add(refcount_t *rc, void *holder) 145168404Spjd{ 146168404Spjd return (refcount_add_many(rc, 1, holder)); 147168404Spjd} 148168404Spjd 149168404Spjdint64_t 150168404Spjdrefcount_remove_many(refcount_t *rc, uint64_t number, void *holder) 151168404Spjd{ 152168404Spjd reference_t *ref; 153168404Spjd int64_t count; 154168404Spjd 155168404Spjd mutex_enter(&rc->rc_mtx); 156168404Spjd ASSERT(rc->rc_count >= number); 157168404Spjd 158248571Smm if (!rc->rc_tracked) { 159168404Spjd rc->rc_count -= number; 160168404Spjd count = rc->rc_count; 161168404Spjd mutex_exit(&rc->rc_mtx); 162168404Spjd return (count); 163168404Spjd } 164168404Spjd 165168404Spjd for (ref = list_head(&rc->rc_list); ref; 166168404Spjd ref = list_next(&rc->rc_list, ref)) { 167168404Spjd if (ref->ref_holder == holder && ref->ref_number == number) { 168168404Spjd list_remove(&rc->rc_list, ref); 169168404Spjd if (reference_history > 0) { 170168404Spjd ref->ref_removed = 171168404Spjd kmem_cache_alloc(reference_history_cache, 172168404Spjd KM_SLEEP); 173168404Spjd list_insert_head(&rc->rc_removed, ref); 174168404Spjd rc->rc_removed_count++; 175248571Smm if (rc->rc_removed_count > reference_history) { 176168404Spjd ref = list_tail(&rc->rc_removed); 177168404Spjd list_remove(&rc->rc_removed, ref); 178168404Spjd kmem_cache_free(reference_history_cache, 179168404Spjd ref->ref_removed); 180168404Spjd kmem_cache_free(reference_cache, ref); 181168404Spjd rc->rc_removed_count--; 182168404Spjd } 183168404Spjd } else { 184168404Spjd kmem_cache_free(reference_cache, ref); 185168404Spjd } 186168404Spjd rc->rc_count -= number; 187168404Spjd count = rc->rc_count; 188168404Spjd mutex_exit(&rc->rc_mtx); 189168404Spjd return (count); 190168404Spjd } 191168404Spjd } 192168404Spjd panic("No such hold %p on refcount %llx", holder, 193168404Spjd (u_longlong_t)(uintptr_t)rc); 194168404Spjd return (-1); 195168404Spjd} 196168404Spjd 197168404Spjdint64_t 198168404Spjdrefcount_remove(refcount_t *rc, void *holder) 199168404Spjd{ 200168404Spjd return (refcount_remove_many(rc, 1, holder)); 201168404Spjd} 202168404Spjd 203219089Spjdvoid 204219089Spjdrefcount_transfer(refcount_t *dst, refcount_t *src) 205219089Spjd{ 206219089Spjd int64_t count, removed_count; 207219089Spjd list_t list, removed; 208219089Spjd 209219089Spjd list_create(&list, sizeof (reference_t), 210219089Spjd offsetof(reference_t, ref_link)); 211219089Spjd list_create(&removed, sizeof (reference_t), 212219089Spjd offsetof(reference_t, ref_link)); 213219089Spjd 214219089Spjd mutex_enter(&src->rc_mtx); 215219089Spjd count = src->rc_count; 216219089Spjd removed_count = src->rc_removed_count; 217219089Spjd src->rc_count = 0; 218219089Spjd src->rc_removed_count = 0; 219219089Spjd list_move_tail(&list, &src->rc_list); 220219089Spjd list_move_tail(&removed, &src->rc_removed); 221219089Spjd mutex_exit(&src->rc_mtx); 222219089Spjd 223219089Spjd mutex_enter(&dst->rc_mtx); 224219089Spjd dst->rc_count += count; 225219089Spjd dst->rc_removed_count += removed_count; 226219089Spjd list_move_tail(&dst->rc_list, &list); 227219089Spjd list_move_tail(&dst->rc_removed, &removed); 228219089Spjd mutex_exit(&dst->rc_mtx); 229219089Spjd 230219089Spjd list_destroy(&list); 231219089Spjd list_destroy(&removed); 232219089Spjd} 233219089Spjd 234219089Spjd#endif /* ZFS_DEBUG */ 235