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 static int 59 zfs_refcount_compare(const void *x1, const void *x2) 60 { 61 const reference_t *r1 = (const reference_t *)x1; 62 const reference_t *r2 = (const reference_t *)x2; 63 64 int cmp1 = TREE_CMP(r1->ref_holder, r2->ref_holder); 65 int cmp2 = TREE_CMP(r1->ref_number, r2->ref_number); 66 int cmp = cmp1 ? cmp1 : cmp2; 67 return ((cmp || r1->ref_search) ? cmp : TREE_PCMP(r1, r2)); 68 } 69 70 void 71 zfs_refcount_create(zfs_refcount_t *rc) 72 { 73 mutex_init(&rc->rc_mtx, NULL, MUTEX_DEFAULT, NULL); 74 avl_create(&rc->rc_tree, zfs_refcount_compare, sizeof (reference_t), 75 offsetof(reference_t, ref_link.a)); 76 list_create(&rc->rc_removed, sizeof (reference_t), 77 offsetof(reference_t, ref_link.l)); 78 rc->rc_count = 0; 79 rc->rc_removed_count = 0; 80 rc->rc_tracked = reference_tracking_enable; 81 } 82 83 void 84 zfs_refcount_create_tracked(zfs_refcount_t *rc) 85 { 86 zfs_refcount_create(rc); 87 rc->rc_tracked = B_TRUE; 88 } 89 90 void 91 zfs_refcount_create_untracked(zfs_refcount_t *rc) 92 { 93 zfs_refcount_create(rc); 94 rc->rc_tracked = B_FALSE; 95 } 96 97 void 98 zfs_refcount_destroy_many(zfs_refcount_t *rc, uint64_t number) 99 { 100 reference_t *ref; 101 void *cookie = NULL; 102 103 ASSERT3U(rc->rc_count, ==, number); 104 while ((ref = avl_destroy_nodes(&rc->rc_tree, &cookie)) != NULL) 105 kmem_cache_free(reference_cache, ref); 106 avl_destroy(&rc->rc_tree); 107 108 while ((ref = list_remove_head(&rc->rc_removed))) { 109 kmem_cache_free(reference_history_cache, ref->ref_removed); 110 kmem_cache_free(reference_cache, ref); 111 } 112 list_destroy(&rc->rc_removed); 113 mutex_destroy(&rc->rc_mtx); 114 } 115 116 void 117 zfs_refcount_destroy(zfs_refcount_t *rc) 118 { 119 zfs_refcount_destroy_many(rc, 0); 120 } 121 122 int 123 zfs_refcount_is_zero(zfs_refcount_t *rc) 124 { 125 return (zfs_refcount_count(rc) == 0); 126 } 127 128 int64_t 129 zfs_refcount_count(zfs_refcount_t *rc) 130 { 131 return (atomic_load_64(&rc->rc_count)); 132 } 133 134 int64_t 135 zfs_refcount_add_many(zfs_refcount_t *rc, uint64_t number, const void *holder) 136 { 137 reference_t *ref; 138 int64_t count; 139 140 if (likely(!rc->rc_tracked)) { 141 count = atomic_add_64_nv(&(rc)->rc_count, number); 142 ASSERT3U(count, >=, number); 143 return (count); 144 } 145 146 ref = kmem_cache_alloc(reference_cache, KM_SLEEP); 147 ref->ref_holder = holder; 148 ref->ref_number = number; 149 ref->ref_search = B_FALSE; 150 mutex_enter(&rc->rc_mtx); 151 avl_add(&rc->rc_tree, ref); 152 rc->rc_count += number; 153 count = rc->rc_count; 154 mutex_exit(&rc->rc_mtx); 155 156 return (count); 157 } 158 159 int64_t 160 zfs_refcount_add(zfs_refcount_t *rc, const void *holder) 161 { 162 return (zfs_refcount_add_many(rc, 1, holder)); 163 } 164 165 void 166 zfs_refcount_add_few(zfs_refcount_t *rc, uint64_t number, const void *holder) 167 { 168 if (likely(!rc->rc_tracked)) { 169 (void) zfs_refcount_add_many(rc, number, holder); 170 } else { 171 for (; number > 0; number--) 172 (void) zfs_refcount_add(rc, holder); 173 } 174 } 175 176 int64_t 177 zfs_refcount_remove_many(zfs_refcount_t *rc, uint64_t number, 178 const void *holder) 179 { 180 reference_t *ref, s; 181 int64_t count; 182 183 if (likely(!rc->rc_tracked)) { 184 count = atomic_add_64_nv(&(rc)->rc_count, -number); 185 ASSERT3S(count, >=, 0); 186 return (count); 187 } 188 189 s.ref_holder = holder; 190 s.ref_number = number; 191 s.ref_search = B_TRUE; 192 mutex_enter(&rc->rc_mtx); 193 ASSERT3U(rc->rc_count, >=, number); 194 ref = avl_find(&rc->rc_tree, &s, NULL); 195 if (unlikely(ref == NULL)) { 196 panic("No such hold %p with count %" PRIu64 " on refcount %llx", 197 holder, number, (u_longlong_t)(uintptr_t)rc); 198 } 199 avl_remove(&rc->rc_tree, ref); 200 if (reference_history > 0) { 201 ref->ref_removed = kmem_cache_alloc(reference_history_cache, 202 KM_SLEEP); 203 list_insert_head(&rc->rc_removed, ref); 204 if (rc->rc_removed_count >= reference_history) { 205 ref = list_remove_tail(&rc->rc_removed); 206 kmem_cache_free(reference_history_cache, 207 ref->ref_removed); 208 kmem_cache_free(reference_cache, ref); 209 } else { 210 rc->rc_removed_count++; 211 } 212 } else { 213 kmem_cache_free(reference_cache, ref); 214 } 215 rc->rc_count -= number; 216 count = rc->rc_count; 217 mutex_exit(&rc->rc_mtx); 218 return (count); 219 } 220 221 int64_t 222 zfs_refcount_remove(zfs_refcount_t *rc, const void *holder) 223 { 224 return (zfs_refcount_remove_many(rc, 1, holder)); 225 } 226 227 void 228 zfs_refcount_remove_few(zfs_refcount_t *rc, uint64_t number, const void *holder) 229 { 230 if (likely(!rc->rc_tracked)) { 231 (void) zfs_refcount_remove_many(rc, number, holder); 232 } else { 233 for (; number > 0; number--) 234 (void) zfs_refcount_remove(rc, holder); 235 } 236 } 237 238 void 239 zfs_refcount_transfer(zfs_refcount_t *dst, zfs_refcount_t *src) 240 { 241 avl_tree_t tree; 242 list_t removed; 243 reference_t *ref; 244 void *cookie = NULL; 245 uint64_t count; 246 uint_t removed_count; 247 248 avl_create(&tree, zfs_refcount_compare, sizeof (reference_t), 249 offsetof(reference_t, ref_link.a)); 250 list_create(&removed, sizeof (reference_t), 251 offsetof(reference_t, ref_link.l)); 252 253 mutex_enter(&src->rc_mtx); 254 count = src->rc_count; 255 removed_count = src->rc_removed_count; 256 src->rc_count = 0; 257 src->rc_removed_count = 0; 258 avl_swap(&tree, &src->rc_tree); 259 list_move_tail(&removed, &src->rc_removed); 260 mutex_exit(&src->rc_mtx); 261 262 mutex_enter(&dst->rc_mtx); 263 dst->rc_count += count; 264 dst->rc_removed_count += removed_count; 265 if (avl_is_empty(&dst->rc_tree)) 266 avl_swap(&dst->rc_tree, &tree); 267 else while ((ref = avl_destroy_nodes(&tree, &cookie)) != NULL) 268 avl_add(&dst->rc_tree, ref); 269 list_move_tail(&dst->rc_removed, &removed); 270 mutex_exit(&dst->rc_mtx); 271 272 avl_destroy(&tree); 273 list_destroy(&removed); 274 } 275 276 void 277 zfs_refcount_transfer_ownership_many(zfs_refcount_t *rc, uint64_t number, 278 const void *current_holder, const void *new_holder) 279 { 280 reference_t *ref, s; 281 282 if (likely(!rc->rc_tracked)) 283 return; 284 285 s.ref_holder = current_holder; 286 s.ref_number = number; 287 s.ref_search = B_TRUE; 288 mutex_enter(&rc->rc_mtx); 289 ref = avl_find(&rc->rc_tree, &s, NULL); 290 ASSERT3P(ref, !=, NULL); 291 ref->ref_holder = new_holder; 292 avl_update(&rc->rc_tree, ref); 293 mutex_exit(&rc->rc_mtx); 294 } 295 296 void 297 zfs_refcount_transfer_ownership(zfs_refcount_t *rc, const void *current_holder, 298 const void *new_holder) 299 { 300 zfs_refcount_transfer_ownership_many(rc, 1, current_holder, 301 new_holder); 302 } 303 304 /* 305 * If tracking is enabled, return true if a reference exists that matches 306 * the "holder" tag. If tracking is disabled, then return true if a reference 307 * might be held. 308 */ 309 boolean_t 310 zfs_refcount_held(zfs_refcount_t *rc, const void *holder) 311 { 312 reference_t *ref, s; 313 avl_index_t idx; 314 boolean_t res; 315 316 if (likely(!rc->rc_tracked)) 317 return (zfs_refcount_count(rc) > 0); 318 319 s.ref_holder = holder; 320 s.ref_number = 0; 321 s.ref_search = B_TRUE; 322 mutex_enter(&rc->rc_mtx); 323 ref = avl_find(&rc->rc_tree, &s, &idx); 324 if (likely(ref == NULL)) 325 ref = avl_nearest(&rc->rc_tree, idx, AVL_AFTER); 326 res = ref && ref->ref_holder == holder; 327 mutex_exit(&rc->rc_mtx); 328 return (res); 329 } 330 331 /* 332 * If tracking is enabled, return true if a reference does not exist that 333 * matches the "holder" tag. If tracking is disabled, always return true 334 * since the reference might not be held. 335 */ 336 boolean_t 337 zfs_refcount_not_held(zfs_refcount_t *rc, const void *holder) 338 { 339 reference_t *ref, s; 340 avl_index_t idx; 341 boolean_t res; 342 343 if (likely(!rc->rc_tracked)) 344 return (B_TRUE); 345 346 mutex_enter(&rc->rc_mtx); 347 s.ref_holder = holder; 348 s.ref_number = 0; 349 s.ref_search = B_TRUE; 350 ref = avl_find(&rc->rc_tree, &s, &idx); 351 if (likely(ref == NULL)) 352 ref = avl_nearest(&rc->rc_tree, idx, AVL_AFTER); 353 res = ref == NULL || ref->ref_holder != holder; 354 mutex_exit(&rc->rc_mtx); 355 return (res); 356 } 357 #endif /* ZFS_DEBUG */ 358