sys/cddl/contrib/opensolaris/uts/common/fs/zfs/refcount.c

   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, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include <sys/zfs_context.h>
  30 #include <sys/refcount.h>
  31
  32 #if defined(DEBUG) || !defined(_KERNEL)
  33
  34 #ifdef _KERNEL
  35 int reference_tracking_enable = FALSE; /* runs out of memory too easily */
  36 #else
  37 int reference_tracking_enable = TRUE;
  38 #endif
  39 int reference_history = 4; /* tunable */
  40
  41 static kmem_cache_t *reference_cache;
  42 static kmem_cache_t *reference_history_cache;
  43
  44 void
  45 refcount_sysinit(void)
  46 {
  47         reference_cache = kmem_cache_create("reference_cache",
  48             sizeof (reference_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
  49
  50         reference_history_cache = kmem_cache_create("reference_history_cache",
  51             sizeof (uint64_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
  52 }
  53
  54 void
  55 refcount_fini(void)
  56 {
  57         kmem_cache_destroy(reference_cache);
  58         kmem_cache_destroy(reference_history_cache);
  59 }
  60
  61 void
  62 refcount_create(refcount_t *rc)
  63 {
  64         list_create(&rc->rc_list, sizeof (reference_t),
  65             offsetof(reference_t, ref_link));
  66         list_create(&rc->rc_removed, sizeof (reference_t),
  67             offsetof(reference_t, ref_link));
  68         mutex_init(&rc->rc_mtx, NULL, MUTEX_DEFAULT, NULL);
  69 }
  70
  71 void
  72 refcount_destroy_many(refcount_t *rc, uint64_t number)
  73 {
  74         reference_t *ref;
  75
  76         ASSERT(rc->rc_count == number);
  77         while (ref = list_head(&rc->rc_list)) {
  78                 list_remove(&rc->rc_list, ref);
  79                 kmem_cache_free(reference_cache, ref);
  80         }
  81         list_destroy(&rc->rc_list);
  82
  83         while (ref = list_head(&rc->rc_removed)) {
  84                 list_remove(&rc->rc_removed, ref);
  85                 kmem_cache_free(reference_history_cache, ref->ref_removed);
  86                 kmem_cache_free(reference_cache, ref);
  87         }
  88         list_destroy(&rc->rc_removed);
  89         mutex_destroy(&rc->rc_mtx);
  90 }
  91
  92 void
  93 refcount_destroy(refcount_t *rc)
  94 {
  95         refcount_destroy_many(rc, 0);
  96 }
  97
  98 int
  99 refcount_is_zero(refcount_t *rc)
 100 {
 101         ASSERT(rc->rc_count >= 0);
 102         return (rc->rc_count == 0);
 103 }
 104
 105 int64_t
 106 refcount_count(refcount_t *rc)
 107 {
 108         ASSERT(rc->rc_count >= 0);
 109         return (rc->rc_count);
 110 }
 111
 112 int64_t
 113 refcount_add_many(refcount_t *rc, uint64_t number, void *holder)
 114 {
 115         reference_t *ref;
 116         int64_t count;
 117
 118         if (reference_tracking_enable) {
 119                 ref = kmem_cache_alloc(reference_cache, KM_SLEEP);
 120                 ref->ref_holder = holder;
 121                 ref->ref_number = number;
 122         }
 123         mutex_enter(&rc->rc_mtx);
 124         ASSERT(rc->rc_count >= 0);
 125         if (reference_tracking_enable)
 126                 list_insert_head(&rc->rc_list, ref);
 127         rc->rc_count += number;
 128         count = rc->rc_count;
 129         mutex_exit(&rc->rc_mtx);
 130
 131         return (count);
 132 }
 133
 134 int64_t
 135 refcount_add(refcount_t *rc, void *holder)
 136 {
 137         return (refcount_add_many(rc, 1, holder));
 138 }
 139
 140 int64_t
 141 refcount_remove_many(refcount_t *rc, uint64_t number, void *holder)
 142 {
 143         reference_t *ref;
 144         int64_t count;
 145
 146         mutex_enter(&rc->rc_mtx);
 147         ASSERT(rc->rc_count >= number);
 148
 149         if (!reference_tracking_enable) {
 150                 rc->rc_count -= number;
 151                 count = rc->rc_count;
 152                 mutex_exit(&rc->rc_mtx);
 153                 return (count);
 154         }
 155
 156         for (ref = list_head(&rc->rc_list); ref;
 157             ref = list_next(&rc->rc_list, ref)) {
 158                 if (ref->ref_holder == holder && ref->ref_number == number) {
 159                         list_remove(&rc->rc_list, ref);
 160                         if (reference_history > 0) {
 161                                 ref->ref_removed =
 162                                     kmem_cache_alloc(reference_history_cache,
 163                                     KM_SLEEP);
 164                                 list_insert_head(&rc->rc_removed, ref);
 165                                 rc->rc_removed_count++;
 166                                 if (rc->rc_removed_count >= reference_history) {
 167                                         ref = list_tail(&rc->rc_removed);
 168                                         list_remove(&rc->rc_removed, ref);
 169                                         kmem_cache_free(reference_history_cache,
 170                                             ref->ref_removed);
 171                                         kmem_cache_free(reference_cache, ref);
 172                                         rc->rc_removed_count--;
 173                                 }
 174                         } else {
 175                                 kmem_cache_free(reference_cache, ref);
 176                         }
 177                         rc->rc_count -= number;
 178                         count = rc->rc_count;
 179                         mutex_exit(&rc->rc_mtx);
 180                         return (count);
 181                 }
 182         }
 183         panic("No such hold %p on refcount %llx", holder,
 184             (u_longlong_t)(uintptr_t)rc);
 185         return (-1);
 186 }
 187
 188 int64_t
 189 refcount_remove(refcount_t *rc, void *holder)
 190 {
 191         return (refcount_remove_many(rc, 1, holder));
 192 }
 193
 194 #endif