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/avl.h>
30 #include <sys/unique.h>
31
32 static avl_tree_t unique_avl;
33 static kmutex_t unique_mtx;
34
35 typedef struct unique {
36 avl_node_t un_link;
37 uint64_t un_value;
38 } unique_t;
39
40 #define UNIQUE_MASK ((1ULL << UNIQUE_BITS) - 1)
41
42 static int
unique_compare(const void * a,const void * b)43 unique_compare(const void *a, const void *b)
44 {
45 const unique_t *una = a;
46 const unique_t *unb = b;
47
48 if (una->un_value < unb->un_value)
49 return (-1);
50 if (una->un_value > unb->un_value)
51 return (+1);
52 return (0);
53 }
54
55 void
unique_init(void)56 unique_init(void)
57 {
58 avl_create(&unique_avl, unique_compare,
59 sizeof (unique_t), offsetof(unique_t, un_link));
60 mutex_init(&unique_mtx, NULL, MUTEX_DEFAULT, NULL);
61 }
62
63 void
unique_fini(void)64 unique_fini(void)
65 {
66 avl_destroy(&unique_avl);
67 mutex_destroy(&unique_mtx);
68 }
69
70 uint64_t
unique_create(void)71 unique_create(void)
72 {
73 uint64_t value = unique_insert(0);
74 unique_remove(value);
75 return (value);
76 }
77
78 uint64_t
unique_insert(uint64_t value)79 unique_insert(uint64_t value)
80 {
81 avl_index_t idx;
82 unique_t *un = kmem_alloc(sizeof (unique_t), KM_SLEEP);
83
84 un->un_value = value;
85
86 mutex_enter(&unique_mtx);
87 while (un->un_value == 0 || un->un_value & ~UNIQUE_MASK ||
88 avl_find(&unique_avl, un, &idx)) {
89 mutex_exit(&unique_mtx);
90 (void) random_get_pseudo_bytes((void*)&un->un_value,
91 sizeof (un->un_value));
92 un->un_value &= UNIQUE_MASK;
93 mutex_enter(&unique_mtx);
94 }
95
96 avl_insert(&unique_avl, un, idx);
97 mutex_exit(&unique_mtx);
98
99 return (un->un_value);
100 }
101
102 void
unique_remove(uint64_t value)103 unique_remove(uint64_t value)
104 {
105 unique_t un_tofind;
106 unique_t *un;
107
108 un_tofind.un_value = value;
109 mutex_enter(&unique_mtx);
110 un = avl_find(&unique_avl, &un_tofind, NULL);
111 if (un != NULL) {
112 avl_remove(&unique_avl, un);
113 kmem_free(un, sizeof (unique_t));
114 }
115 mutex_exit(&unique_mtx);
116 }
117