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 https://opensource.org/licenses/CDDL-1.0.
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
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 = (const unique_t *)a;
46 const unique_t *unb = (const unique_t *)b;
47
48 return (TREE_CMP(una->un_value, unb->un_value));
49 }
50
51 void
unique_init(void)52 unique_init(void)
53 {
54 avl_create(&unique_avl, unique_compare,
55 sizeof (unique_t), offsetof(unique_t, un_link));
56 mutex_init(&unique_mtx, NULL, MUTEX_DEFAULT, NULL);
57 }
58
59 void
unique_fini(void)60 unique_fini(void)
61 {
62 avl_destroy(&unique_avl);
63 mutex_destroy(&unique_mtx);
64 }
65
66 uint64_t
unique_create(void)67 unique_create(void)
68 {
69 uint64_t value = unique_insert(0);
70 unique_remove(value);
71 return (value);
72 }
73
74 uint64_t
unique_insert(uint64_t value)75 unique_insert(uint64_t value)
76 {
77 avl_index_t idx;
78 unique_t *un = kmem_alloc(sizeof (unique_t), KM_SLEEP);
79
80 un->un_value = value;
81
82 mutex_enter(&unique_mtx);
83 while (un->un_value == 0 || un->un_value & ~UNIQUE_MASK ||
84 avl_find(&unique_avl, un, &idx)) {
85 mutex_exit(&unique_mtx);
86 (void) random_get_pseudo_bytes((void*)&un->un_value,
87 sizeof (un->un_value));
88 un->un_value &= UNIQUE_MASK;
89 mutex_enter(&unique_mtx);
90 }
91
92 avl_insert(&unique_avl, un, idx);
93 mutex_exit(&unique_mtx);
94
95 return (un->un_value);
96 }
97
98 void
unique_remove(uint64_t value)99 unique_remove(uint64_t value)
100 {
101 unique_t un_tofind;
102 unique_t *un;
103
104 un_tofind.un_value = value;
105 mutex_enter(&unique_mtx);
106 un = avl_find(&unique_avl, &un_tofind, NULL);
107 if (un != NULL) {
108 avl_remove(&unique_avl, un);
109 kmem_free(un, sizeof (unique_t));
110 }
111 mutex_exit(&unique_mtx);
112 }
113