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. 23307277Smav * Copyright (c) 2012, 2015 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 76307277Smavrefcount_create_tracked(refcount_t *rc) 77307277Smav{ 78307277Smav refcount_create(rc); 79307277Smav rc->rc_tracked = B_TRUE; 80307277Smav} 81307277Smav 82307277Smavvoid 83248571Smmrefcount_create_untracked(refcount_t *rc) 84248571Smm{ 85248571Smm refcount_create(rc); 86248571Smm rc->rc_tracked = B_FALSE; 87248571Smm} 88248571Smm 89248571Smmvoid 90168404Spjdrefcount_destroy_many(refcount_t *rc, uint64_t number) 91168404Spjd{ 92168404Spjd reference_t *ref; 93168404Spjd 94168404Spjd ASSERT(rc->rc_count == number); 95168404Spjd while (ref = list_head(&rc->rc_list)) { 96168404Spjd list_remove(&rc->rc_list, ref); 97168404Spjd kmem_cache_free(reference_cache, ref); 98168404Spjd } 99168404Spjd list_destroy(&rc->rc_list); 100168404Spjd 101168404Spjd while (ref = list_head(&rc->rc_removed)) { 102168404Spjd list_remove(&rc->rc_removed, ref); 103168404Spjd kmem_cache_free(reference_history_cache, ref->ref_removed); 104168404Spjd kmem_cache_free(reference_cache, ref); 105168404Spjd } 106168404Spjd list_destroy(&rc->rc_removed); 107168404Spjd mutex_destroy(&rc->rc_mtx); 108168404Spjd} 109168404Spjd 110168404Spjdvoid 111168404Spjdrefcount_destroy(refcount_t *rc) 112168404Spjd{ 113168404Spjd refcount_destroy_many(rc, 0); 114168404Spjd} 115168404Spjd 116168404Spjdint 117168404Spjdrefcount_is_zero(refcount_t *rc) 118168404Spjd{ 119168404Spjd return (rc->rc_count == 0); 120168404Spjd} 121168404Spjd 122168404Spjdint64_t 123168404Spjdrefcount_count(refcount_t *rc) 124168404Spjd{ 125168404Spjd return (rc->rc_count); 126168404Spjd} 127168404Spjd 128168404Spjdint64_t 129168404Spjdrefcount_add_many(refcount_t *rc, uint64_t number, void *holder) 130168404Spjd{ 131247187Smm reference_t *ref = NULL; 132168404Spjd int64_t count; 133168404Spjd 134248571Smm if (rc->rc_tracked) { 135168404Spjd ref = kmem_cache_alloc(reference_cache, KM_SLEEP); 136168404Spjd ref->ref_holder = holder; 137168404Spjd ref->ref_number = number; 138168404Spjd } 139168404Spjd mutex_enter(&rc->rc_mtx); 140168404Spjd ASSERT(rc->rc_count >= 0); 141248571Smm if (rc->rc_tracked) 142168404Spjd list_insert_head(&rc->rc_list, ref); 143168404Spjd rc->rc_count += number; 144168404Spjd count = rc->rc_count; 145168404Spjd mutex_exit(&rc->rc_mtx); 146168404Spjd 147168404Spjd return (count); 148168404Spjd} 149168404Spjd 150168404Spjdint64_t 151168404Spjdrefcount_add(refcount_t *rc, void *holder) 152168404Spjd{ 153168404Spjd return (refcount_add_many(rc, 1, holder)); 154168404Spjd} 155168404Spjd 156168404Spjdint64_t 157168404Spjdrefcount_remove_many(refcount_t *rc, uint64_t number, void *holder) 158168404Spjd{ 159168404Spjd reference_t *ref; 160168404Spjd int64_t count; 161168404Spjd 162168404Spjd mutex_enter(&rc->rc_mtx); 163168404Spjd ASSERT(rc->rc_count >= number); 164168404Spjd 165248571Smm if (!rc->rc_tracked) { 166168404Spjd rc->rc_count -= number; 167168404Spjd count = rc->rc_count; 168168404Spjd mutex_exit(&rc->rc_mtx); 169168404Spjd return (count); 170168404Spjd } 171168404Spjd 172168404Spjd for (ref = list_head(&rc->rc_list); ref; 173168404Spjd ref = list_next(&rc->rc_list, ref)) { 174168404Spjd if (ref->ref_holder == holder && ref->ref_number == number) { 175168404Spjd list_remove(&rc->rc_list, ref); 176168404Spjd if (reference_history > 0) { 177168404Spjd ref->ref_removed = 178168404Spjd kmem_cache_alloc(reference_history_cache, 179168404Spjd KM_SLEEP); 180168404Spjd list_insert_head(&rc->rc_removed, ref); 181168404Spjd rc->rc_removed_count++; 182248571Smm if (rc->rc_removed_count > reference_history) { 183168404Spjd ref = list_tail(&rc->rc_removed); 184168404Spjd list_remove(&rc->rc_removed, ref); 185168404Spjd kmem_cache_free(reference_history_cache, 186168404Spjd ref->ref_removed); 187168404Spjd kmem_cache_free(reference_cache, ref); 188168404Spjd rc->rc_removed_count--; 189168404Spjd } 190168404Spjd } else { 191168404Spjd kmem_cache_free(reference_cache, ref); 192168404Spjd } 193168404Spjd rc->rc_count -= number; 194168404Spjd count = rc->rc_count; 195168404Spjd mutex_exit(&rc->rc_mtx); 196168404Spjd return (count); 197168404Spjd } 198168404Spjd } 199168404Spjd panic("No such hold %p on refcount %llx", holder, 200168404Spjd (u_longlong_t)(uintptr_t)rc); 201168404Spjd return (-1); 202168404Spjd} 203168404Spjd 204168404Spjdint64_t 205168404Spjdrefcount_remove(refcount_t *rc, void *holder) 206168404Spjd{ 207168404Spjd return (refcount_remove_many(rc, 1, holder)); 208168404Spjd} 209168404Spjd 210219089Spjdvoid 211219089Spjdrefcount_transfer(refcount_t *dst, refcount_t *src) 212219089Spjd{ 213219089Spjd int64_t count, removed_count; 214219089Spjd list_t list, removed; 215219089Spjd 216219089Spjd list_create(&list, sizeof (reference_t), 217219089Spjd offsetof(reference_t, ref_link)); 218219089Spjd list_create(&removed, sizeof (reference_t), 219219089Spjd offsetof(reference_t, ref_link)); 220219089Spjd 221219089Spjd mutex_enter(&src->rc_mtx); 222219089Spjd count = src->rc_count; 223219089Spjd removed_count = src->rc_removed_count; 224219089Spjd src->rc_count = 0; 225219089Spjd src->rc_removed_count = 0; 226219089Spjd list_move_tail(&list, &src->rc_list); 227219089Spjd list_move_tail(&removed, &src->rc_removed); 228219089Spjd mutex_exit(&src->rc_mtx); 229219089Spjd 230219089Spjd mutex_enter(&dst->rc_mtx); 231219089Spjd dst->rc_count += count; 232219089Spjd dst->rc_removed_count += removed_count; 233219089Spjd list_move_tail(&dst->rc_list, &list); 234219089Spjd list_move_tail(&dst->rc_removed, &removed); 235219089Spjd mutex_exit(&dst->rc_mtx); 236219089Spjd 237219089Spjd list_destroy(&list); 238219089Spjd list_destroy(&removed); 239219089Spjd} 240219089Spjd 241307265Smavvoid 242307265Smavrefcount_transfer_ownership(refcount_t *rc, void *current_holder, 243307265Smav void *new_holder) 244307265Smav{ 245307265Smav reference_t *ref; 246307265Smav boolean_t found = B_FALSE; 247307265Smav 248307265Smav mutex_enter(&rc->rc_mtx); 249307265Smav if (!rc->rc_tracked) { 250307265Smav mutex_exit(&rc->rc_mtx); 251307265Smav return; 252307265Smav } 253307265Smav 254307265Smav for (ref = list_head(&rc->rc_list); ref; 255307265Smav ref = list_next(&rc->rc_list, ref)) { 256307265Smav if (ref->ref_holder == current_holder) { 257307265Smav ref->ref_holder = new_holder; 258307265Smav found = B_TRUE; 259307265Smav break; 260307265Smav } 261307265Smav } 262307265Smav ASSERT(found); 263307265Smav mutex_exit(&rc->rc_mtx); 264307265Smav} 265307277Smav 266307277Smav/* 267307277Smav * If tracking is enabled, return true if a reference exists that matches 268307277Smav * the "holder" tag. If tracking is disabled, then return true if a reference 269307277Smav * might be held. 270307277Smav */ 271307277Smavboolean_t 272307277Smavrefcount_held(refcount_t *rc, void *holder) 273307277Smav{ 274307277Smav reference_t *ref; 275307277Smav 276307277Smav mutex_enter(&rc->rc_mtx); 277307277Smav 278307277Smav if (!rc->rc_tracked) { 279307277Smav mutex_exit(&rc->rc_mtx); 280307277Smav return (rc->rc_count > 0); 281307277Smav } 282307277Smav 283307277Smav for (ref = list_head(&rc->rc_list); ref; 284307277Smav ref = list_next(&rc->rc_list, ref)) { 285307277Smav if (ref->ref_holder == holder) { 286307277Smav mutex_exit(&rc->rc_mtx); 287307277Smav return (B_TRUE); 288307277Smav } 289307277Smav } 290307277Smav mutex_exit(&rc->rc_mtx); 291307277Smav return (B_FALSE); 292307277Smav} 293307277Smav 294307277Smav/* 295307277Smav * If tracking is enabled, return true if a reference does not exist that 296307277Smav * matches the "holder" tag. If tracking is disabled, always return true 297307277Smav * since the reference might not be held. 298307277Smav */ 299307277Smavboolean_t 300307277Smavrefcount_not_held(refcount_t *rc, void *holder) 301307277Smav{ 302307277Smav reference_t *ref; 303307277Smav 304307277Smav mutex_enter(&rc->rc_mtx); 305307277Smav 306307277Smav if (!rc->rc_tracked) { 307307277Smav mutex_exit(&rc->rc_mtx); 308307277Smav return (B_TRUE); 309307277Smav } 310307277Smav 311307277Smav for (ref = list_head(&rc->rc_list); ref; 312307277Smav ref = list_next(&rc->rc_list, ref)) { 313307277Smav if (ref->ref_holder == holder) { 314307277Smav mutex_exit(&rc->rc_mtx); 315307277Smav return (B_FALSE); 316307277Smav } 317307277Smav } 318307277Smav mutex_exit(&rc->rc_mtx); 319307277Smav return (B_TRUE); 320307277Smav} 321219089Spjd#endif /* ZFS_DEBUG */ 322