1168404Spjd/* 2168404Spjd * CDDL HEADER START 3168404Spjd * 4168404Spjd * The contents of this file are subject to the terms of the 5168404Spjd * Common Development and Distribution License (the "License"). 6168404Spjd * 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/* 22168404Spjd * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. 23219089Spjd * Copyright (c) 2012, 2015 by Delphix. All rights reserved. 24307122Smav */ 25297112Smav 26168404Spjd#include <sys/zfs_context.h> 27168404Spjd#include <sys/refcount.h> 28185029Spjd 29168404Spjd#ifdef ZFS_DEBUG 30168404Spjd 31168404Spjd#ifdef _KERNEL 32185029Spjdint reference_tracking_enable = FALSE; /* runs out of memory too easily */ 33185029SpjdSYSCTL_DECL(_vfs_zfs); 34248571SmmTUNABLE_INT("vfs.zfs.reference_tracking_enable", &reference_tracking_enable); 35248571SmmSYSCTL_INT(_vfs_zfs, OID_AUTO, reference_tracking_enable, CTLFLAG_RDTUN, 36185029Spjd &reference_tracking_enable, 0, 37185029Spjd "Track reference holders to refcount_t objects, used mostly by ZFS"); 38248571Smm#else 39219089Spjdint reference_tracking_enable = TRUE; 40185029Spjd#endif 41185029Spjdint reference_history = 3; /* tunable */ 42185029Spjd 43185029Spjdstatic kmem_cache_t *reference_cache; 44168404Spjdstatic kmem_cache_t *reference_history_cache; 45168404Spjd 46168404Spjdvoid 47168404Spjdrefcount_sysinit(void) 48168404Spjd{ 49168404Spjd reference_cache = kmem_cache_create("reference_cache", 50168404Spjd sizeof (reference_t), 0, NULL, NULL, NULL, NULL, NULL, 0); 51168404Spjd 52168404Spjd reference_history_cache = kmem_cache_create("reference_history_cache", 53168404Spjd sizeof (uint64_t), 0, NULL, NULL, NULL, NULL, NULL, 0); 54168404Spjd} 55168404Spjd 56168404Spjdvoid 57168404Spjdrefcount_fini(void) 58168404Spjd{ 59168404Spjd kmem_cache_destroy(reference_cache); 60168404Spjd kmem_cache_destroy(reference_history_cache); 61168404Spjd} 62168404Spjd 63168404Spjdvoid 64168404Spjdrefcount_create(refcount_t *rc) 65168404Spjd{ 66168404Spjd mutex_init(&rc->rc_mtx, NULL, MUTEX_DEFAULT, NULL); 67168404Spjd list_create(&rc->rc_list, sizeof (reference_t), 68168404Spjd offsetof(reference_t, ref_link)); 69168404Spjd list_create(&rc->rc_removed, sizeof (reference_t), 70168404Spjd offsetof(reference_t, ref_link)); 71168404Spjd rc->rc_count = 0; 72168404Spjd rc->rc_removed_count = 0; 73168404Spjd rc->rc_tracked = reference_tracking_enable; 74168404Spjd} 75168404Spjd 76168404Spjdvoid 77168404Spjdrefcount_create_tracked(refcount_t *rc) 78168404Spjd{ 79168404Spjd refcount_create(rc); 80168404Spjd rc->rc_tracked = B_TRUE; 81168404Spjd} 82168404Spjd 83168404Spjdvoid 84168404Spjdrefcount_create_untracked(refcount_t *rc) 85168404Spjd{ 86168404Spjd refcount_create(rc); 87168404Spjd rc->rc_tracked = B_FALSE; 88168404Spjd} 89168404Spjd 90168404Spjdvoid 91168404Spjdrefcount_destroy_many(refcount_t *rc, uint64_t number) 92168404Spjd{ 93168404Spjd reference_t *ref; 94276081Sdelphij 95168404Spjd ASSERT(rc->rc_count == number); 96168404Spjd while (ref = list_head(&rc->rc_list)) { 97168404Spjd list_remove(&rc->rc_list, ref); 98168404Spjd kmem_cache_free(reference_cache, ref); 99168404Spjd } 100168404Spjd list_destroy(&rc->rc_list); 101168404Spjd 102168404Spjd while (ref = list_head(&rc->rc_removed)) { 103168404Spjd list_remove(&rc->rc_removed, ref); 104168404Spjd kmem_cache_free(reference_history_cache, ref->ref_removed); 105168404Spjd kmem_cache_free(reference_cache, ref); 106168404Spjd } 107168404Spjd list_destroy(&rc->rc_removed); 108168404Spjd mutex_destroy(&rc->rc_mtx); 109228103Smm} 110168404Spjd 111219089Spjdvoid 112228103Smmrefcount_destroy(refcount_t *rc) 113228103Smm{ 114168404Spjd refcount_destroy_many(rc, 0); 115168404Spjd} 116168404Spjd 117168404Spjdint 118168404Spjdrefcount_is_zero(refcount_t *rc) 119168404Spjd{ 120168404Spjd return (rc->rc_count == 0); 121168404Spjd} 122168404Spjd 123168404Spjdint64_t 124168404Spjdrefcount_count(refcount_t *rc) 125168404Spjd{ 126168404Spjd return (rc->rc_count); 127168404Spjd} 128168404Spjd 129168404Spjdint64_t 130168404Spjdrefcount_add_many(refcount_t *rc, uint64_t number, void *holder) 131168404Spjd{ 132168404Spjd reference_t *ref = NULL; 133168404Spjd int64_t count; 134209962Smm 135168404Spjd if (rc->rc_tracked) { 136168404Spjd ref = kmem_cache_alloc(reference_cache, KM_SLEEP); 137168404Spjd ref->ref_holder = holder; 138168404Spjd ref->ref_number = number; 139209962Smm } 140168404Spjd mutex_enter(&rc->rc_mtx); 141168404Spjd ASSERT(rc->rc_count >= 0); 142168404Spjd if (rc->rc_tracked) 143168404Spjd list_insert_head(&rc->rc_list, ref); 144168404Spjd rc->rc_count += number; 145168404Spjd count = rc->rc_count; 146168404Spjd mutex_exit(&rc->rc_mtx); 147168404Spjd 148168404Spjd return (count); 149168404Spjd} 150168404Spjd 151168404Spjdint64_t 152168404Spjdrefcount_add(refcount_t *rc, void *holder) 153168404Spjd{ 154168404Spjd return (refcount_add_many(rc, 1, holder)); 155168404Spjd} 156168404Spjd 157168404Spjdint64_t 158168404Spjdrefcount_remove_many(refcount_t *rc, uint64_t number, void *holder) 159168404Spjd{ 160168404Spjd reference_t *ref; 161168404Spjd int64_t count; 162185029Spjd 163168404Spjd mutex_enter(&rc->rc_mtx); 164185029Spjd ASSERT(rc->rc_count >= number); 165168404Spjd 166168404Spjd if (!rc->rc_tracked) { 167168404Spjd rc->rc_count -= number; 168168404Spjd count = rc->rc_count; 169168404Spjd mutex_exit(&rc->rc_mtx); 170168404Spjd return (count); 171168404Spjd } 172168404Spjd 173168404Spjd for (ref = list_head(&rc->rc_list); ref; 174168404Spjd ref = list_next(&rc->rc_list, ref)) { 175168404Spjd if (ref->ref_holder == holder && ref->ref_number == number) { 176168404Spjd list_remove(&rc->rc_list, ref); 177168404Spjd if (reference_history > 0) { 178168404Spjd ref->ref_removed = 179168404Spjd kmem_cache_alloc(reference_history_cache, 180168404Spjd KM_SLEEP); 181168404Spjd list_insert_head(&rc->rc_removed, ref); 182185029Spjd rc->rc_removed_count++; 183248571Smm if (rc->rc_removed_count > reference_history) { 184185029Spjd ref = list_tail(&rc->rc_removed); 185185029Spjd list_remove(&rc->rc_removed, ref); 186194118Sjamie kmem_cache_free(reference_history_cache, 187185029Spjd ref->ref_removed); 188194118Sjamie kmem_cache_free(reference_cache, ref); 189185029Spjd rc->rc_removed_count--; 190248571Smm } 191185029Spjd } else { 192185029Spjd kmem_cache_free(reference_cache, ref); 193168404Spjd } 194168404Spjd rc->rc_count -= number; 195168404Spjd count = rc->rc_count; 196219089Spjd mutex_exit(&rc->rc_mtx); 197185029Spjd return (count); 198248571Smm } 199168404Spjd } 200248571Smm panic("No such hold %p on refcount %llx", holder, 201248571Smm (u_longlong_t)(uintptr_t)rc); 202168404Spjd return (-1); 203168404Spjd} 204168404Spjd 205168404Spjdint64_t 206168404Spjdrefcount_remove(refcount_t *rc, void *holder) 207168404Spjd{ 208168404Spjd return (refcount_remove_many(rc, 1, holder)); 209168404Spjd} 210168404Spjd 211168404Spjdvoid 212168404Spjdrefcount_transfer(refcount_t *dst, refcount_t *src) 213168404Spjd{ 214168404Spjd int64_t count, removed_count; 215168404Spjd list_t list, removed; 216168404Spjd 217168404Spjd list_create(&list, sizeof (reference_t), 218168404Spjd offsetof(reference_t, ref_link)); 219168404Spjd list_create(&removed, sizeof (reference_t), 220168404Spjd offsetof(reference_t, ref_link)); 221168404Spjd 222168404Spjd mutex_enter(&src->rc_mtx); 223248571Smm count = src->rc_count; 224168404Spjd removed_count = src->rc_removed_count; 225168404Spjd src->rc_count = 0; 226168404Spjd src->rc_removed_count = 0; 227168404Spjd list_move_tail(&list, &src->rc_list); 228168404Spjd list_move_tail(&removed, &src->rc_removed); 229168404Spjd mutex_exit(&src->rc_mtx); 230168404Spjd 231168404Spjd mutex_enter(&dst->rc_mtx); 232168404Spjd dst->rc_count += count; 233168404Spjd dst->rc_removed_count += removed_count; 234168404Spjd list_move_tail(&dst->rc_list, &list); 235168404Spjd list_move_tail(&dst->rc_removed, &removed); 236248571Smm mutex_exit(&dst->rc_mtx); 237185029Spjd 238248571Smm list_destroy(&list); 239185029Spjd list_destroy(&removed); 240248571Smm} 241248571Smm 242248571Smmvoid 243248571Smmrefcount_transfer_ownership(refcount_t *rc, void *current_holder, 244248571Smm void *new_holder) 245248571Smm{ 246248571Smm reference_t *ref; 247248571Smm boolean_t found = B_FALSE; 248248571Smm 249248571Smm mutex_enter(&rc->rc_mtx); 250248571Smm if (!rc->rc_tracked) { 251248571Smm mutex_exit(&rc->rc_mtx); 252248571Smm return; 253248571Smm } 254248571Smm 255248571Smm for (ref = list_head(&rc->rc_list); ref; 256248571Smm ref = list_next(&rc->rc_list, ref)) { 257248571Smm if (ref->ref_holder == current_holder) { 258248571Smm ref->ref_holder = new_holder; 259248571Smm found = B_TRUE; 260185029Spjd break; 261185029Spjd } 262248571Smm } 263185029Spjd ASSERT(found); 264168404Spjd mutex_exit(&rc->rc_mtx); 265168404Spjd} 266168404Spjd 267168404Spjd/* 268168404Spjd * If tracking is enabled, return true if a reference exists that matches 269168404Spjd * the "holder" tag. If tracking is disabled, then return true if a reference 270168404Spjd * might be held. 271168404Spjd */ 272248571Smmboolean_t 273248571Smmrefcount_held(refcount_t *rc, void *holder) 274248571Smm{ 275248571Smm reference_t *ref; 276168404Spjd 277168404Spjd mutex_enter(&rc->rc_mtx); 278168404Spjd 279248571Smm if (!rc->rc_tracked) { 280168404Spjd mutex_exit(&rc->rc_mtx); 281248571Smm return (rc->rc_count > 0); 282168404Spjd } 283168404Spjd 284168404Spjd for (ref = list_head(&rc->rc_list); ref; 285168404Spjd ref = list_next(&rc->rc_list, ref)) { 286168404Spjd if (ref->ref_holder == holder) { 287168404Spjd mutex_exit(&rc->rc_mtx); 288248571Smm return (B_TRUE); 289168404Spjd } 290248571Smm } 291248571Smm mutex_exit(&rc->rc_mtx); 292248571Smm return (B_FALSE); 293248571Smm} 294248571Smm 295248571Smm/* 296248571Smm * If tracking is enabled, return true if a reference does not exist that 297248571Smm * matches the "holder" tag. If tracking is disabled, always return true 298248571Smm * since the reference might not be held. 299248571Smm */ 300248571Smmboolean_t 301248571Smmrefcount_not_held(refcount_t *rc, void *holder) 302219089Spjd{ 303219089Spjd reference_t *ref; 304248571Smm 305168404Spjd mutex_enter(&rc->rc_mtx); 306248571Smm 307248571Smm if (!rc->rc_tracked) { 308185029Spjd mutex_exit(&rc->rc_mtx); 309240133Smm return (B_TRUE); 310249195Smm } 311240133Smm 312219089Spjd for (ref = list_head(&rc->rc_list); ref; 313219089Spjd ref = list_next(&rc->rc_list, ref)) { 314219089Spjd if (ref->ref_holder == holder) { 315219089Spjd mutex_exit(&rc->rc_mtx); 316219089Spjd return (B_FALSE); 317219089Spjd } 318219089Spjd } 319248571Smm mutex_exit(&rc->rc_mtx); 320248571Smm return (B_TRUE); 321248571Smm} 322248571Smm#endif /* ZFS_DEBUG */ 323248571Smm