1 // SPDX-License-Identifier: CDDL-1.0 2 /* 3 * CDDL HEADER START 4 * 5 * The contents of this file are subject to the terms of the 6 * Common Development and Distribution License (the "License"). 7 * You may not use this file except in compliance with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or https://opensource.org/licenses/CDDL-1.0. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright 2009 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 /* 27 * Copyright (c) 2013, 2019 by Delphix. All rights reserved. 28 */ 29 30 #include <sys/zfs_context.h> 31 #include <sys/range_tree.h> 32 #include <sys/space_reftree.h> 33 34 /* 35 * Space reference trees. 36 * 37 * A range tree is a collection of integers. Every integer is either 38 * in the tree, or it's not. A space reference tree generalizes 39 * the idea: it allows its members to have arbitrary reference counts, 40 * as opposed to the implicit reference count of 0 or 1 in a range tree. 41 * This representation comes in handy when computing the union or 42 * intersection of multiple space maps. For example, the union of 43 * N range trees is the subset of the reference tree with refcnt >= 1. 44 * The intersection of N range trees is the subset with refcnt >= N. 45 * 46 * [It's very much like a Fourier transform. Unions and intersections 47 * are hard to perform in the 'range tree domain', so we convert the trees 48 * into the 'reference count domain', where it's trivial, then invert.] 49 * 50 * vdev_dtl_reassess() uses computations of this form to determine 51 * DTL_MISSING and DTL_OUTAGE for interior vdevs -- e.g. a RAID-Z vdev 52 * has an outage wherever refcnt >= vdev_nparity + 1, and a mirror vdev 53 * has an outage wherever refcnt >= vdev_children. 54 */ 55 static int 56 space_reftree_compare(const void *x1, const void *x2) 57 { 58 const space_ref_t *sr1 = (const space_ref_t *)x1; 59 const space_ref_t *sr2 = (const space_ref_t *)x2; 60 61 int cmp = TREE_CMP(sr1->sr_offset, sr2->sr_offset); 62 if (likely(cmp)) 63 return (cmp); 64 65 return (TREE_PCMP(sr1, sr2)); 66 } 67 68 void 69 space_reftree_create(avl_tree_t *t) 70 { 71 avl_create(t, space_reftree_compare, 72 sizeof (space_ref_t), offsetof(space_ref_t, sr_node)); 73 } 74 75 void 76 space_reftree_destroy(avl_tree_t *t) 77 { 78 space_ref_t *sr; 79 void *cookie = NULL; 80 81 while ((sr = avl_destroy_nodes(t, &cookie)) != NULL) 82 kmem_free(sr, sizeof (*sr)); 83 84 avl_destroy(t); 85 } 86 87 static void 88 space_reftree_add_node(avl_tree_t *t, uint64_t offset, int64_t refcnt) 89 { 90 space_ref_t *sr; 91 92 sr = kmem_alloc(sizeof (*sr), KM_SLEEP); 93 sr->sr_offset = offset; 94 sr->sr_refcnt = refcnt; 95 96 avl_add(t, sr); 97 } 98 99 void 100 space_reftree_add_seg(avl_tree_t *t, uint64_t start, uint64_t end, 101 int64_t refcnt) 102 { 103 space_reftree_add_node(t, start, refcnt); 104 space_reftree_add_node(t, end, -refcnt); 105 } 106 107 /* 108 * Convert (or add) a range tree into a reference tree. 109 */ 110 void 111 space_reftree_add_map(avl_tree_t *t, zfs_range_tree_t *rt, int64_t refcnt) 112 { 113 zfs_btree_index_t where; 114 115 for (zfs_range_seg_t *rs = zfs_btree_first(&rt->rt_root, &where); rs; 116 rs = zfs_btree_next(&rt->rt_root, &where, &where)) { 117 space_reftree_add_seg(t, zfs_rs_get_start(rs, rt), 118 zfs_rs_get_end(rs, rt), refcnt); 119 } 120 } 121 122 /* 123 * Convert a reference tree into a range tree. The range tree will contain 124 * all members of the reference tree for which refcnt >= minref. 125 */ 126 void 127 space_reftree_generate_map(avl_tree_t *t, zfs_range_tree_t *rt, int64_t minref) 128 { 129 uint64_t start = -1ULL; 130 int64_t refcnt = 0; 131 space_ref_t *sr; 132 133 zfs_range_tree_vacate(rt, NULL, NULL); 134 135 for (sr = avl_first(t); sr != NULL; sr = AVL_NEXT(t, sr)) { 136 refcnt += sr->sr_refcnt; 137 if (refcnt >= minref) { 138 if (start == -1ULL) { 139 start = sr->sr_offset; 140 } 141 } else { 142 if (start != -1ULL) { 143 uint64_t end = sr->sr_offset; 144 ASSERT(start <= end); 145 if (end > start) 146 zfs_range_tree_add(rt, start, end - 147 start); 148 start = -1ULL; 149 } 150 } 151 } 152 ASSERT(refcnt == 0); 153 ASSERT(start == -1ULL); 154 } 155