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-rw-r--r--uts/common/fs/zfs/refcount.c223
1 files changed, 223 insertions, 0 deletions
diff --git a/uts/common/fs/zfs/refcount.c b/uts/common/fs/zfs/refcount.c
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+++ b/uts/common/fs/zfs/refcount.c
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+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ */
+
+#include <sys/zfs_context.h>
+#include <sys/refcount.h>
+
+#ifdef ZFS_DEBUG
+
+#ifdef _KERNEL
+int reference_tracking_enable = FALSE; /* runs out of memory too easily */
+#else
+int reference_tracking_enable = TRUE;
+#endif
+int reference_history = 4; /* tunable */
+
+static kmem_cache_t *reference_cache;
+static kmem_cache_t *reference_history_cache;
+
+void
+refcount_init(void)
+{
+ reference_cache = kmem_cache_create("reference_cache",
+ sizeof (reference_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
+
+ reference_history_cache = kmem_cache_create("reference_history_cache",
+ sizeof (uint64_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
+}
+
+void
+refcount_fini(void)
+{
+ kmem_cache_destroy(reference_cache);
+ kmem_cache_destroy(reference_history_cache);
+}
+
+void
+refcount_create(refcount_t *rc)
+{
+ mutex_init(&rc->rc_mtx, NULL, MUTEX_DEFAULT, NULL);
+ list_create(&rc->rc_list, sizeof (reference_t),
+ offsetof(reference_t, ref_link));
+ list_create(&rc->rc_removed, sizeof (reference_t),
+ offsetof(reference_t, ref_link));
+ rc->rc_count = 0;
+ rc->rc_removed_count = 0;
+}
+
+void
+refcount_destroy_many(refcount_t *rc, uint64_t number)
+{
+ reference_t *ref;
+
+ ASSERT(rc->rc_count == number);
+ while (ref = list_head(&rc->rc_list)) {
+ list_remove(&rc->rc_list, ref);
+ kmem_cache_free(reference_cache, ref);
+ }
+ list_destroy(&rc->rc_list);
+
+ while (ref = list_head(&rc->rc_removed)) {
+ list_remove(&rc->rc_removed, ref);
+ kmem_cache_free(reference_history_cache, ref->ref_removed);
+ kmem_cache_free(reference_cache, ref);
+ }
+ list_destroy(&rc->rc_removed);
+ mutex_destroy(&rc->rc_mtx);
+}
+
+void
+refcount_destroy(refcount_t *rc)
+{
+ refcount_destroy_many(rc, 0);
+}
+
+int
+refcount_is_zero(refcount_t *rc)
+{
+ ASSERT(rc->rc_count >= 0);
+ return (rc->rc_count == 0);
+}
+
+int64_t
+refcount_count(refcount_t *rc)
+{
+ ASSERT(rc->rc_count >= 0);
+ return (rc->rc_count);
+}
+
+int64_t
+refcount_add_many(refcount_t *rc, uint64_t number, void *holder)
+{
+ reference_t *ref;
+ int64_t count;
+
+ if (reference_tracking_enable) {
+ ref = kmem_cache_alloc(reference_cache, KM_SLEEP);
+ ref->ref_holder = holder;
+ ref->ref_number = number;
+ }
+ mutex_enter(&rc->rc_mtx);
+ ASSERT(rc->rc_count >= 0);
+ if (reference_tracking_enable)
+ list_insert_head(&rc->rc_list, ref);
+ rc->rc_count += number;
+ count = rc->rc_count;
+ mutex_exit(&rc->rc_mtx);
+
+ return (count);
+}
+
+int64_t
+refcount_add(refcount_t *rc, void *holder)
+{
+ return (refcount_add_many(rc, 1, holder));
+}
+
+int64_t
+refcount_remove_many(refcount_t *rc, uint64_t number, void *holder)
+{
+ reference_t *ref;
+ int64_t count;
+
+ mutex_enter(&rc->rc_mtx);
+ ASSERT(rc->rc_count >= number);
+
+ if (!reference_tracking_enable) {
+ rc->rc_count -= number;
+ count = rc->rc_count;
+ mutex_exit(&rc->rc_mtx);
+ return (count);
+ }
+
+ for (ref = list_head(&rc->rc_list); ref;
+ ref = list_next(&rc->rc_list, ref)) {
+ if (ref->ref_holder == holder && ref->ref_number == number) {
+ list_remove(&rc->rc_list, ref);
+ if (reference_history > 0) {
+ ref->ref_removed =
+ kmem_cache_alloc(reference_history_cache,
+ KM_SLEEP);
+ list_insert_head(&rc->rc_removed, ref);
+ rc->rc_removed_count++;
+ if (rc->rc_removed_count >= reference_history) {
+ ref = list_tail(&rc->rc_removed);
+ list_remove(&rc->rc_removed, ref);
+ kmem_cache_free(reference_history_cache,
+ ref->ref_removed);
+ kmem_cache_free(reference_cache, ref);
+ rc->rc_removed_count--;
+ }
+ } else {
+ kmem_cache_free(reference_cache, ref);
+ }
+ rc->rc_count -= number;
+ count = rc->rc_count;
+ mutex_exit(&rc->rc_mtx);
+ return (count);
+ }
+ }
+ panic("No such hold %p on refcount %llx", holder,
+ (u_longlong_t)(uintptr_t)rc);
+ return (-1);
+}
+
+int64_t
+refcount_remove(refcount_t *rc, void *holder)
+{
+ return (refcount_remove_many(rc, 1, holder));
+}
+
+void
+refcount_transfer(refcount_t *dst, refcount_t *src)
+{
+ int64_t count, removed_count;
+ list_t list, removed;
+
+ list_create(&list, sizeof (reference_t),
+ offsetof(reference_t, ref_link));
+ list_create(&removed, sizeof (reference_t),
+ offsetof(reference_t, ref_link));
+
+ mutex_enter(&src->rc_mtx);
+ count = src->rc_count;
+ removed_count = src->rc_removed_count;
+ src->rc_count = 0;
+ src->rc_removed_count = 0;
+ list_move_tail(&list, &src->rc_list);
+ list_move_tail(&removed, &src->rc_removed);
+ mutex_exit(&src->rc_mtx);
+
+ mutex_enter(&dst->rc_mtx);
+ dst->rc_count += count;
+ dst->rc_removed_count += removed_count;
+ list_move_tail(&dst->rc_list, &list);
+ list_move_tail(&dst->rc_removed, &removed);
+ mutex_exit(&dst->rc_mtx);
+
+ list_destroy(&list);
+ list_destroy(&removed);
+}
+
+#endif /* ZFS_DEBUG */