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 #include <sys/zfs_context.h> 27 #include <sys/avl.h> 28 #include <sys/unique.h> 29 30 static avl_tree_t unique_avl; 31 static kmutex_t unique_mtx; 32 33 typedef struct unique { 34 avl_node_t un_link; 35 uint64_t un_value; 36 } unique_t; 37 38 #define UNIQUE_MASK ((1ULL << UNIQUE_BITS) - 1) 39 40 static int 41 unique_compare(const void *a, const void *b) 42 { 43 const unique_t *una = (const unique_t *)a; 44 const unique_t *unb = (const unique_t *)b; 45 46 return (TREE_CMP(una->un_value, unb->un_value)); 47 } 48 49 void 50 unique_init(void) 51 { 52 avl_create(&unique_avl, unique_compare, 53 sizeof (unique_t), offsetof(unique_t, un_link)); 54 mutex_init(&unique_mtx, NULL, MUTEX_DEFAULT, NULL); 55 } 56 57 void 58 unique_fini(void) 59 { 60 avl_destroy(&unique_avl); 61 mutex_destroy(&unique_mtx); 62 } 63 64 uint64_t 65 unique_create(void) 66 { 67 uint64_t value = unique_insert(0); 68 unique_remove(value); 69 return (value); 70 } 71 72 uint64_t 73 unique_insert(uint64_t value) 74 { 75 avl_index_t idx; 76 unique_t *un = kmem_alloc(sizeof (unique_t), KM_SLEEP); 77 78 un->un_value = value; 79 80 mutex_enter(&unique_mtx); 81 while (un->un_value == 0 || un->un_value & ~UNIQUE_MASK || 82 avl_find(&unique_avl, un, &idx)) { 83 mutex_exit(&unique_mtx); 84 (void) random_get_pseudo_bytes((void*)&un->un_value, 85 sizeof (un->un_value)); 86 un->un_value &= UNIQUE_MASK; 87 mutex_enter(&unique_mtx); 88 } 89 90 avl_insert(&unique_avl, un, idx); 91 mutex_exit(&unique_mtx); 92 93 return (un->un_value); 94 } 95 96 void 97 unique_remove(uint64_t value) 98 { 99 unique_t un_tofind; 100 unique_t *un; 101 102 un_tofind.un_value = value; 103 mutex_enter(&unique_mtx); 104 un = avl_find(&unique_avl, &un_tofind, NULL); 105 if (un != NULL) { 106 avl_remove(&unique_avl, un); 107 kmem_free(un, sizeof (unique_t)); 108 } 109 mutex_exit(&unique_mtx); 110 } 111