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 2006 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; /* Lock never initialized. */ 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 } 61 62 uint64_t 63 unique_create(void) 64 { 65 return (unique_insert(0)); 66 } 67 68 uint64_t 69 unique_insert(uint64_t value) 70 { 71 avl_index_t idx; 72 unique_t *un = kmem_alloc(sizeof (unique_t), KM_SLEEP); 73 74 un->un_value = value; 75 76 mutex_enter(&unique_mtx); 77 while (un->un_value == 0 || un->un_value & ~UNIQUE_MASK || 78 avl_find(&unique_avl, un, &idx)) { 79 mutex_exit(&unique_mtx); 80 (void) random_get_pseudo_bytes((void*)&un->un_value, 81 sizeof (un->un_value)); 82 un->un_value &= UNIQUE_MASK; 83 mutex_enter(&unique_mtx); 84 } 85 86 avl_insert(&unique_avl, un, idx); 87 mutex_exit(&unique_mtx); 88 89 return (un->un_value); 90 } 91 92 void 93 unique_remove(uint64_t value) 94 { 95 unique_t un_tofind; 96 unique_t *un; 97 98 un_tofind.un_value = value; 99 mutex_enter(&unique_mtx); 100 un = avl_find(&unique_avl, &un_tofind, NULL); 101 if (un != NULL) { 102 avl_remove(&unique_avl, un); 103 kmem_free(un, sizeof (unique_t)); 104 } 105 mutex_exit(&unique_mtx); 106 } 107