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 2009 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 /* 26 * Copyright (c) 2013 by Delphix. All rights reserved. 27 */ 28 29 #include <sys/zfs_context.h> 30 #include <sys/range_tree.h> 31 #include <sys/space_reftree.h> 32 33 /* 34 * Space reference trees. 35 * 36 * A range tree is a collection of integers. Every integer is either 37 * in the tree, or it's not. A space reference tree generalizes 38 * the idea: it allows its members to have arbitrary reference counts, 39 * as opposed to the implicit reference count of 0 or 1 in a range tree. 40 * This representation comes in handy when computing the union or 41 * intersection of multiple space maps. For example, the union of 42 * N range trees is the subset of the reference tree with refcnt >= 1. 43 * The intersection of N range trees is the subset with refcnt >= N. 44 * 45 * [It's very much like a Fourier transform. Unions and intersections 46 * are hard to perform in the 'range tree domain', so we convert the trees 47 * into the 'reference count domain', where it's trivial, then invert.] 48 * 49 * vdev_dtl_reassess() uses computations of this form to determine 50 * DTL_MISSING and DTL_OUTAGE for interior vdevs -- e.g. a RAID-Z vdev 51 * has an outage wherever refcnt >= vdev_nparity + 1, and a mirror vdev 52 * has an outage wherever refcnt >= vdev_children. 53 */ 54 static int 55 space_reftree_compare(const void *x1, const void *x2) 56 { 57 const space_ref_t *sr1 = x1; 58 const space_ref_t *sr2 = x2; 59 60 if (sr1->sr_offset < sr2->sr_offset) 61 return (-1); 62 if (sr1->sr_offset > sr2->sr_offset) 63 return (1); 64 65 if (sr1 < sr2) 66 return (-1); 67 if (sr1 > sr2) 68 return (1); 69 70 return (0); 71 } 72 73 void 74 space_reftree_create(avl_tree_t *t) 75 { 76 avl_create(t, space_reftree_compare, 77 sizeof (space_ref_t), offsetof(space_ref_t, sr_node)); 78 } 79 80 void 81 space_reftree_destroy(avl_tree_t *t) 82 { 83 space_ref_t *sr; 84 void *cookie = NULL; 85 86 while ((sr = avl_destroy_nodes(t, &cookie)) != NULL) 87 kmem_free(sr, sizeof (*sr)); 88 89 avl_destroy(t); 90 } 91 92 static void 93 space_reftree_add_node(avl_tree_t *t, uint64_t offset, int64_t refcnt) 94 { 95 space_ref_t *sr; 96 97 sr = kmem_alloc(sizeof (*sr), KM_SLEEP); 98 sr->sr_offset = offset; 99 sr->sr_refcnt = refcnt; 100 101 avl_add(t, sr); 102 } 103 104 void 105 space_reftree_add_seg(avl_tree_t *t, uint64_t start, uint64_t end, 106 int64_t refcnt) 107 { 108 space_reftree_add_node(t, start, refcnt); 109 space_reftree_add_node(t, end, -refcnt); 110 } 111 112 /* 113 * Convert (or add) a range tree into a reference tree. 114 */ 115 void 116 space_reftree_add_map(avl_tree_t *t, range_tree_t *rt, int64_t refcnt) 117 { 118 range_seg_t *rs; 119 120 ASSERT(MUTEX_HELD(rt->rt_lock)); 121 122 for (rs = avl_first(&rt->rt_root); rs; rs = AVL_NEXT(&rt->rt_root, rs)) 123 space_reftree_add_seg(t, rs->rs_start, rs->rs_end, refcnt); 124 } 125 126 /* 127 * Convert a reference tree into a range tree. The range tree will contain 128 * all members of the reference tree for which refcnt >= minref. 129 */ 130 void 131 space_reftree_generate_map(avl_tree_t *t, range_tree_t *rt, int64_t minref) 132 { 133 uint64_t start = -1ULL; 134 int64_t refcnt = 0; 135 space_ref_t *sr; 136 137 ASSERT(MUTEX_HELD(rt->rt_lock)); 138 139 range_tree_vacate(rt, NULL, NULL); 140 141 for (sr = avl_first(t); sr != NULL; sr = AVL_NEXT(t, sr)) { 142 refcnt += sr->sr_refcnt; 143 if (refcnt >= minref) { 144 if (start == -1ULL) { 145 start = sr->sr_offset; 146 } 147 } else { 148 if (start != -1ULL) { 149 uint64_t end = sr->sr_offset; 150 ASSERT(start <= end); 151 if (end > start) 152 range_tree_add(rt, start, end - start); 153 start = -1ULL; 154 } 155 } 156 } 157 ASSERT(refcnt == 0); 158 ASSERT(start == -1ULL); 159 } 160