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, 2015 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 32 int reference_tracking_enable = FALSE; /* runs out of memory too easily */ 33 #else 34 int reference_tracking_enable = TRUE; 35 #endif 36 int reference_history = 3; /* tunable */ 37 38 static kmem_cache_t *reference_cache; 39 static kmem_cache_t *reference_history_cache; 40 41 void 42 zfs_refcount_init(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 51 void 52 zfs_refcount_fini(void) 53 { 54 kmem_cache_destroy(reference_cache); 55 kmem_cache_destroy(reference_history_cache); 56 } 57 58 void 59 zfs_refcount_create(zfs_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 71 void 72 zfs_refcount_create_tracked(zfs_refcount_t *rc) 73 { 74 zfs_refcount_create(rc); 75 rc->rc_tracked = B_TRUE; 76 } 77 78 void 79 zfs_refcount_create_untracked(zfs_refcount_t *rc) 80 { 81 zfs_refcount_create(rc); 82 rc->rc_tracked = B_FALSE; 83 } 84 85 void 86 zfs_refcount_destroy_many(zfs_refcount_t *rc, uint64_t number) 87 { 88 reference_t *ref; 89 90 ASSERT(rc->rc_count == number); 91 while (ref = list_head(&rc->rc_list)) { 92 list_remove(&rc->rc_list, ref); 93 kmem_cache_free(reference_cache, ref); 94 } 95 list_destroy(&rc->rc_list); 96 97 while (ref = list_head(&rc->rc_removed)) { 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 107 zfs_refcount_destroy(zfs_refcount_t *rc) 108 { 109 zfs_refcount_destroy_many(rc, 0); 110 } 111 112 int 113 zfs_refcount_is_zero(zfs_refcount_t *rc) 114 { 115 return (rc->rc_count == 0); 116 } 117 118 int64_t 119 zfs_refcount_count(zfs_refcount_t *rc) 120 { 121 return (rc->rc_count); 122 } 123 124 int64_t 125 zfs_refcount_add_many(zfs_refcount_t *rc, uint64_t number, const void *holder) 126 { 127 reference_t *ref = NULL; 128 int64_t count; 129 130 if (rc->rc_tracked) { 131 ref = kmem_cache_alloc(reference_cache, KM_SLEEP); 132 ref->ref_holder = holder; 133 ref->ref_number = number; 134 } 135 mutex_enter(&rc->rc_mtx); 136 ASSERT(rc->rc_count >= 0); 137 if (rc->rc_tracked) 138 list_insert_head(&rc->rc_list, ref); 139 rc->rc_count += number; 140 count = rc->rc_count; 141 mutex_exit(&rc->rc_mtx); 142 143 return (count); 144 } 145 146 int64_t 147 zfs_refcount_add(zfs_refcount_t *rc, const void *holder) 148 { 149 return (zfs_refcount_add_many(rc, 1, holder)); 150 } 151 152 void 153 zfs_refcount_add_few(zfs_refcount_t *rc, uint64_t number, const void *holder) 154 { 155 if (!rc->rc_tracked) { 156 (void) zfs_refcount_add_many(rc, number, holder); 157 } else { 158 for (; number > 0; number--) 159 (void) zfs_refcount_add(rc, holder); 160 } 161 } 162 163 int64_t 164 zfs_refcount_remove_many(zfs_refcount_t *rc, uint64_t number, 165 const void *holder) 166 { 167 reference_t *ref; 168 int64_t count; 169 170 mutex_enter(&rc->rc_mtx); 171 ASSERT(rc->rc_count >= number); 172 173 if (!rc->rc_tracked) { 174 rc->rc_count -= number; 175 count = rc->rc_count; 176 mutex_exit(&rc->rc_mtx); 177 return (count); 178 } 179 180 for (ref = list_head(&rc->rc_list); ref; 181 ref = list_next(&rc->rc_list, ref)) { 182 if (ref->ref_holder == holder && ref->ref_number == number) { 183 list_remove(&rc->rc_list, ref); 184 if (reference_history > 0) { 185 ref->ref_removed = 186 kmem_cache_alloc(reference_history_cache, 187 KM_SLEEP); 188 list_insert_head(&rc->rc_removed, ref); 189 rc->rc_removed_count++; 190 if (rc->rc_removed_count > reference_history) { 191 ref = list_tail(&rc->rc_removed); 192 list_remove(&rc->rc_removed, ref); 193 kmem_cache_free(reference_history_cache, 194 ref->ref_removed); 195 kmem_cache_free(reference_cache, ref); 196 rc->rc_removed_count--; 197 } 198 } else { 199 kmem_cache_free(reference_cache, ref); 200 } 201 rc->rc_count -= number; 202 count = rc->rc_count; 203 mutex_exit(&rc->rc_mtx); 204 return (count); 205 } 206 } 207 panic("No such hold %p with count %" PRIu64 " on refcount %llx", 208 holder, number, (u_longlong_t)(uintptr_t)rc); 209 return (-1); 210 } 211 212 int64_t 213 zfs_refcount_remove(zfs_refcount_t *rc, const void *holder) 214 { 215 return (zfs_refcount_remove_many(rc, 1, holder)); 216 } 217 218 void 219 zfs_refcount_remove_few(zfs_refcount_t *rc, uint64_t number, const void *holder) 220 { 221 if (!rc->rc_tracked) { 222 (void) zfs_refcount_remove_many(rc, number, holder); 223 } else { 224 for (; number > 0; number--) 225 (void) zfs_refcount_remove(rc, holder); 226 } 227 } 228 229 void 230 zfs_refcount_transfer(zfs_refcount_t *dst, zfs_refcount_t *src) 231 { 232 int64_t count, removed_count; 233 list_t list, removed; 234 235 list_create(&list, sizeof (reference_t), 236 offsetof(reference_t, ref_link)); 237 list_create(&removed, sizeof (reference_t), 238 offsetof(reference_t, ref_link)); 239 240 mutex_enter(&src->rc_mtx); 241 count = src->rc_count; 242 removed_count = src->rc_removed_count; 243 src->rc_count = 0; 244 src->rc_removed_count = 0; 245 list_move_tail(&list, &src->rc_list); 246 list_move_tail(&removed, &src->rc_removed); 247 mutex_exit(&src->rc_mtx); 248 249 mutex_enter(&dst->rc_mtx); 250 dst->rc_count += count; 251 dst->rc_removed_count += removed_count; 252 list_move_tail(&dst->rc_list, &list); 253 list_move_tail(&dst->rc_removed, &removed); 254 mutex_exit(&dst->rc_mtx); 255 256 list_destroy(&list); 257 list_destroy(&removed); 258 } 259 260 /* ARGSUSED */ 261 void 262 zfs_refcount_transfer_ownership_many(zfs_refcount_t *rc, uint64_t number, 263 void *current_holder, void *new_holder) 264 { 265 reference_t *ref; 266 boolean_t found = B_FALSE; 267 268 mutex_enter(&rc->rc_mtx); 269 if (!rc->rc_tracked) { 270 mutex_exit(&rc->rc_mtx); 271 return; 272 } 273 274 for (ref = list_head(&rc->rc_list); ref; 275 ref = list_next(&rc->rc_list, ref)) { 276 if (ref->ref_holder == current_holder && 277 ref->ref_number == number) { 278 ref->ref_holder = new_holder; 279 found = B_TRUE; 280 break; 281 } 282 } 283 ASSERT(found); 284 mutex_exit(&rc->rc_mtx); 285 } 286 287 void 288 zfs_refcount_transfer_ownership(zfs_refcount_t *rc, void *current_holder, 289 void *new_holder) 290 { 291 zfs_refcount_transfer_ownership_many(rc, 1, current_holder, 292 new_holder); 293 } 294 295 /* 296 * If tracking is enabled, return true if a reference exists that matches 297 * the "holder" tag. If tracking is disabled, then return true if a reference 298 * might be held. 299 */ 300 boolean_t 301 zfs_refcount_held(zfs_refcount_t *rc, void *holder) 302 { 303 reference_t *ref; 304 305 mutex_enter(&rc->rc_mtx); 306 307 if (!rc->rc_tracked) { 308 mutex_exit(&rc->rc_mtx); 309 return (rc->rc_count > 0); 310 } 311 312 for (ref = list_head(&rc->rc_list); ref; 313 ref = list_next(&rc->rc_list, ref)) { 314 if (ref->ref_holder == holder) { 315 mutex_exit(&rc->rc_mtx); 316 return (B_TRUE); 317 } 318 } 319 mutex_exit(&rc->rc_mtx); 320 return (B_FALSE); 321 } 322 323 /* 324 * If tracking is enabled, return true if a reference does not exist that 325 * matches the "holder" tag. If tracking is disabled, always return true 326 * since the reference might not be held. 327 */ 328 boolean_t 329 zfs_refcount_not_held(zfs_refcount_t *rc, void *holder) 330 { 331 reference_t *ref; 332 333 mutex_enter(&rc->rc_mtx); 334 335 if (!rc->rc_tracked) { 336 mutex_exit(&rc->rc_mtx); 337 return (B_TRUE); 338 } 339 340 for (ref = list_head(&rc->rc_list); ref; 341 ref = list_next(&rc->rc_list, ref)) { 342 if (ref->ref_holder == holder) { 343 mutex_exit(&rc->rc_mtx); 344 return (B_FALSE); 345 } 346 } 347 mutex_exit(&rc->rc_mtx); 348 return (B_TRUE); 349 } 350 #endif /* ZFS_DEBUG */ 351