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 (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 2007 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 #pragma ident   "%Z%%M% %I%     %E% SMI"
  27
  28 #include <sys/zfs_context.h>
  29 #include <sys/refcount.h>
  30
  31 #if defined(DEBUG) || !defined(_KERNEL)
  32
  33 #ifdef _KERNEL
  34 int reference_tracking_enable = FALSE; /* runs out of memory too easily */
  35 #else
  36 int reference_tracking_enable = TRUE;
  37 #endif
  38 int reference_history = 4; /* tunable */
  39
  40 static kmem_cache_t *reference_cache;
  41 static kmem_cache_t *reference_history_cache;
  42
  43 void
  44 refcount_sysinit(void)
  45 {
  46         reference_cache = kmem_cache_create("reference_cache",
  47             sizeof (reference_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
  48
  49         reference_history_cache = kmem_cache_create("reference_history_cache",
  50             sizeof (uint64_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
  51 }
  52
  53 void
  54 refcount_fini(void)
  55 {
  56         kmem_cache_destroy(reference_cache);
  57         kmem_cache_destroy(reference_history_cache);
  58 }
  59
  60 void
  61 refcount_create(refcount_t *rc)
  62 {
  63         mutex_init(&rc->rc_mtx, NULL, MUTEX_DEFAULT, NULL);
  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         rc->rc_count = 0;
  69         rc->rc_removed_count = 0;
  70 }
  71
  72 void
  73 refcount_destroy_many(refcount_t *rc, uint64_t number)
  74 {
  75         reference_t *ref;
  76
  77         ASSERT(rc->rc_count == number);
  78         while (ref = list_head(&rc->rc_list)) {
  79                 list_remove(&rc->rc_list, ref);
  80                 kmem_cache_free(reference_cache, ref);
  81         }
  82         list_destroy(&rc->rc_list);
  83
  84         while (ref = list_head(&rc->rc_removed)) {
  85                 list_remove(&rc->rc_removed, ref);
  86                 kmem_cache_free(reference_history_cache, ref->ref_removed);
  87                 kmem_cache_free(reference_cache, ref);
  88         }
  89         list_destroy(&rc->rc_removed);
  90         mutex_destroy(&rc->rc_mtx);
  91 }
  92
  93 void
  94 refcount_destroy(refcount_t *rc)
  95 {
  96         refcount_destroy_many(rc, 0);
  97 }
  98
  99 int
 100 refcount_is_zero(refcount_t *rc)
 101 {
 102         ASSERT(rc->rc_count >= 0);
 103         return (rc->rc_count == 0);
 104 }
 105
 106 int64_t
 107 refcount_count(refcount_t *rc)
 108 {
 109         ASSERT(rc->rc_count >= 0);
 110         return (rc->rc_count);
 111 }
 112
 113 int64_t
 114 refcount_add_many(refcount_t *rc, uint64_t number, void *holder)
 115 {
 116         reference_t *ref;
 117         int64_t count;
 118
 119         if (reference_tracking_enable) {
 120                 ref = kmem_cache_alloc(reference_cache, KM_SLEEP);
 121                 ref->ref_holder = holder;
 122                 ref->ref_number = number;
 123         }
 124         mutex_enter(&rc->rc_mtx);
 125         ASSERT(rc->rc_count >= 0);
 126         if (reference_tracking_enable)
 127                 list_insert_head(&rc->rc_list, ref);
 128         rc->rc_count += number;
 129         count = rc->rc_count;
 130         mutex_exit(&rc->rc_mtx);
 131
 132         return (count);
 133 }
 134
 135 int64_t
 136 refcount_add(refcount_t *rc, void *holder)
 137 {
 138         return (refcount_add_many(rc, 1, holder));
 139 }
 140
 141 int64_t
 142 refcount_remove_many(refcount_t *rc, uint64_t number, void *holder)
 143 {
 144         reference_t *ref;
 145         int64_t count;
 146
 147         mutex_enter(&rc->rc_mtx);
 148         ASSERT(rc->rc_count >= number);
 149
 150         if (!reference_tracking_enable) {
 151                 rc->rc_count -= number;
 152                 count = rc->rc_count;
 153                 mutex_exit(&rc->rc_mtx);
 154                 return (count);
 155         }
 156
 157         for (ref = list_head(&rc->rc_list); ref;
 158             ref = list_next(&rc->rc_list, ref)) {
 159                 if (ref->ref_holder == holder && ref->ref_number == number) {
 160                         list_remove(&rc->rc_list, ref);
 161                         if (reference_history > 0) {
 162                                 ref->ref_removed =
 163                                     kmem_cache_alloc(reference_history_cache,
 164                                     KM_SLEEP);
 165                                 list_insert_head(&rc->rc_removed, ref);
 166                                 rc->rc_removed_count++;
 167                                 if (rc->rc_removed_count >= reference_history) {
 168                                         ref = list_tail(&rc->rc_removed);
 169                                         list_remove(&rc->rc_removed, ref);
 170                                         kmem_cache_free(reference_history_cache,
 171                                             ref->ref_removed);
 172                                         kmem_cache_free(reference_cache, ref);
 173                                         rc->rc_removed_count--;
 174                                 }
 175                         } else {
 176                                 kmem_cache_free(reference_cache, ref);
 177                         }
 178                         rc->rc_count -= number;
 179                         count = rc->rc_count;
 180                         mutex_exit(&rc->rc_mtx);
 181                         return (count);
 182                 }
 183         }
 184         panic("No such hold %p on refcount %llx", holder,
 185             (u_longlong_t)(uintptr_t)rc);
 186         return (-1);
 187 }
 188
 189 int64_t
 190 refcount_remove(refcount_t *rc, void *holder)
 191 {
 192         return (refcount_remove_many(rc, 1, holder));
 193 }
 194
 195 #endif