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 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 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 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 60 unique_fini(void) 61 { 62 avl_destroy(&unique_avl); 63 mutex_destroy(&unique_mtx); 64 } 65 66 uint64_t 67 unique_create(void) 68 { 69 uint64_t value = unique_insert(0); 70 unique_remove(value); 71 return (value); 72 } 73 74 uint64_t 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 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