113 lines
2.5 KiB
C
113 lines
2.5 KiB
C
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/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright 2007 Sun Microsystems, Inc. All rights reserved.
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* Use is subject to license terms.
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*/
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#include <sys/zfs_context.h>
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#include <sys/avl.h>
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#include <sys/unique.h>
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static avl_tree_t unique_avl;
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static kmutex_t unique_mtx;
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typedef struct unique {
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avl_node_t un_link;
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uint64_t un_value;
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} unique_t;
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#define UNIQUE_MASK ((1ULL << UNIQUE_BITS) - 1)
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static int
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unique_compare(const void *a, const void *b)
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{
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const unique_t *una = (const unique_t *)a;
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const unique_t *unb = (const unique_t *)b;
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return (AVL_CMP(una->un_value, unb->un_value));
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}
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void
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unique_init(void)
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{
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avl_create(&unique_avl, unique_compare,
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sizeof (unique_t), offsetof(unique_t, un_link));
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mutex_init(&unique_mtx, NULL, MUTEX_DEFAULT, NULL);
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}
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void
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unique_fini(void)
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{
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avl_destroy(&unique_avl);
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mutex_destroy(&unique_mtx);
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}
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uint64_t
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unique_create(void)
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{
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uint64_t value = unique_insert(0);
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unique_remove(value);
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return (value);
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}
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uint64_t
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unique_insert(uint64_t value)
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{
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avl_index_t idx;
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unique_t *un = kmem_alloc(sizeof (unique_t), KM_SLEEP);
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un->un_value = value;
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mutex_enter(&unique_mtx);
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while (un->un_value == 0 || un->un_value & ~UNIQUE_MASK ||
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avl_find(&unique_avl, un, &idx)) {
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mutex_exit(&unique_mtx);
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(void) random_get_pseudo_bytes((void*)&un->un_value,
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sizeof (un->un_value));
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un->un_value &= UNIQUE_MASK;
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mutex_enter(&unique_mtx);
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}
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avl_insert(&unique_avl, un, idx);
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mutex_exit(&unique_mtx);
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return (un->un_value);
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}
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void
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unique_remove(uint64_t value)
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{
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unique_t un_tofind;
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unique_t *un;
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un_tofind.un_value = value;
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mutex_enter(&unique_mtx);
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un = avl_find(&unique_avl, &un_tofind, NULL);
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if (un != NULL) {
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avl_remove(&unique_avl, un);
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kmem_free(un, sizeof (unique_t));
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}
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mutex_exit(&unique_mtx);
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}
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