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 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 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 64 unique_fini(void) 65 { 66 avl_destroy(&unique_avl); 67 mutex_destroy(&unique_mtx); 68 } 69 70 uint64_t 71 unique_create(void) 72 { 73 uint64_t value = unique_insert(0); 74 unique_remove(value); 75 return (value); 76 } 77 78 uint64_t 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 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