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 9 * or http://www.opensolaris.org/os/licensing. 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/* 22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. 23 * Copyright (c) 2012 by Delphix. All rights reserved. 24 */ 25 26#include <sys/zfs_context.h> 27#include <sys/refcount.h> 28 29#ifdef ZFS_DEBUG 30 31#ifdef _KERNEL 32int reference_tracking_enable = FALSE; /* runs out of memory too easily */ 33#else 34int reference_tracking_enable = TRUE; 35#endif 36int reference_history = 3; /* tunable */ 37 38static kmem_cache_t *reference_cache; 39static kmem_cache_t *reference_history_cache; 40 41void 42refcount_sysinit(void) 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 51void 52refcount_fini(void) 53{ 54 kmem_cache_destroy(reference_cache); 55 kmem_cache_destroy(reference_history_cache); 56} 57 58void 59refcount_create(refcount_t *rc) 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; 68 rc->rc_tracked = reference_tracking_enable; 69} 70 71void 72refcount_create_untracked(refcount_t *rc) 73{ 74 refcount_create(rc); 75 rc->rc_tracked = B_FALSE; 76} 77 78void 79refcount_destroy_many(refcount_t *rc, uint64_t number) 80{ 81 reference_t *ref; 82 83 ASSERT(rc->rc_count == number); 84 while (ref = list_head(&rc->rc_list)) { 85 list_remove(&rc->rc_list, ref); 86 kmem_cache_free(reference_cache, ref); 87 } 88 list_destroy(&rc->rc_list); 89 90 while (ref = list_head(&rc->rc_removed)) { 91 list_remove(&rc->rc_removed, ref); 92 kmem_cache_free(reference_history_cache, ref->ref_removed); 93 kmem_cache_free(reference_cache, ref); 94 } 95 list_destroy(&rc->rc_removed); 96 mutex_destroy(&rc->rc_mtx); 97} 98 99void 100refcount_destroy(refcount_t *rc) 101{ 102 refcount_destroy_many(rc, 0); 103} 104 105int 106refcount_is_zero(refcount_t *rc) 107{ 108 return (rc->rc_count == 0); 109} 110 111int64_t 112refcount_count(refcount_t *rc) 113{ 114 return (rc->rc_count); 115} 116 117int64_t 118refcount_add_many(refcount_t *rc, uint64_t number, void *holder) 119{ 120 reference_t *ref = NULL; 121 int64_t count; 122 123 if (rc->rc_tracked) { 124 ref = kmem_cache_alloc(reference_cache, KM_SLEEP); 125 ref->ref_holder = holder; 126 ref->ref_number = number; 127 } 128 mutex_enter(&rc->rc_mtx); 129 ASSERT(rc->rc_count >= 0); 130 if (rc->rc_tracked) 131 list_insert_head(&rc->rc_list, ref); 132 rc->rc_count += number; 133 count = rc->rc_count; 134 mutex_exit(&rc->rc_mtx); 135 136 return (count); 137} 138 139int64_t 140refcount_add(refcount_t *rc, void *holder) 141{ 142 return (refcount_add_many(rc, 1, holder)); 143} 144 145int64_t 146refcount_remove_many(refcount_t *rc, uint64_t number, void *holder) 147{ 148 reference_t *ref; 149 int64_t count; 150 151 mutex_enter(&rc->rc_mtx); 152 ASSERT(rc->rc_count >= number); 153 154 if (!rc->rc_tracked) { 155 rc->rc_count -= number; 156 count = rc->rc_count; 157 mutex_exit(&rc->rc_mtx); 158 return (count); 159 } 160 161 for (ref = list_head(&rc->rc_list); ref; 162 ref = list_next(&rc->rc_list, ref)) { 163 if (ref->ref_holder == holder && ref->ref_number == number) { 164 list_remove(&rc->rc_list, ref); 165 if (reference_history > 0) { 166 ref->ref_removed = 167 kmem_cache_alloc(reference_history_cache, 168 KM_SLEEP); 169 list_insert_head(&rc->rc_removed, ref); 170 rc->rc_removed_count++; 171 if (rc->rc_removed_count > reference_history) { 172 ref = list_tail(&rc->rc_removed); 173 list_remove(&rc->rc_removed, ref); 174 kmem_cache_free(reference_history_cache, 175 ref->ref_removed); 176 kmem_cache_free(reference_cache, ref); 177 rc->rc_removed_count--; 178 } 179 } else { 180 kmem_cache_free(reference_cache, ref); 181 } 182 rc->rc_count -= number; 183 count = rc->rc_count; 184 mutex_exit(&rc->rc_mtx); 185 return (count); 186 } 187 } 188 panic("No such hold %p on refcount %llx", holder, 189 (u_longlong_t)(uintptr_t)rc); 190 return (-1); 191} 192 193int64_t 194refcount_remove(refcount_t *rc, void *holder) 195{ 196 return (refcount_remove_many(rc, 1, holder)); 197} 198 199void 200refcount_transfer(refcount_t *dst, refcount_t *src) 201{ 202 int64_t count, removed_count; 203 list_t list, removed; 204 205 list_create(&list, sizeof (reference_t), 206 offsetof(reference_t, ref_link)); 207 list_create(&removed, sizeof (reference_t), 208 offsetof(reference_t, ref_link)); 209 210 mutex_enter(&src->rc_mtx); 211 count = src->rc_count; 212 removed_count = src->rc_removed_count; 213 src->rc_count = 0; 214 src->rc_removed_count = 0; 215 list_move_tail(&list, &src->rc_list); 216 list_move_tail(&removed, &src->rc_removed); 217 mutex_exit(&src->rc_mtx); 218 219 mutex_enter(&dst->rc_mtx); 220 dst->rc_count += count; 221 dst->rc_removed_count += removed_count; 222 list_move_tail(&dst->rc_list, &list); 223 list_move_tail(&dst->rc_removed, &removed); 224 mutex_exit(&dst->rc_mtx); 225 226 list_destroy(&list); 227 list_destroy(&removed); 228} 229 230#endif /* ZFS_DEBUG */ 231