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, 2015 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 = (const space_ref_t *)x1; 58 const space_ref_t *sr2 = (const space_ref_t *)x2; 59 60 int cmp = AVL_CMP(sr1->sr_offset, sr2->sr_offset); 61 if (likely(cmp)) 62 return (cmp); 63 64 return (AVL_PCMP(sr1, sr2)); 65 } 66 67 void 68 space_reftree_create(avl_tree_t *t) 69 { 70 avl_create(t, space_reftree_compare, 71 sizeof (space_ref_t), offsetof(space_ref_t, sr_node)); 72 } 73 74 void 75 space_reftree_destroy(avl_tree_t *t) 76 { 77 space_ref_t *sr; 78 void *cookie = NULL; 79 80 while ((sr = avl_destroy_nodes(t, &cookie)) != NULL) 81 kmem_free(sr, sizeof (*sr)); 82 83 avl_destroy(t); 84 } 85 86 static void 87 space_reftree_add_node(avl_tree_t *t, uint64_t offset, int64_t refcnt) 88 { 89 space_ref_t *sr; 90 91 sr = kmem_alloc(sizeof (*sr), KM_SLEEP); 92 sr->sr_offset = offset; 93 sr->sr_refcnt = refcnt; 94 95 avl_add(t, sr); 96 } 97 98 void 99 space_reftree_add_seg(avl_tree_t *t, uint64_t start, uint64_t end, 100 int64_t refcnt) 101 { 102 space_reftree_add_node(t, start, refcnt); 103 space_reftree_add_node(t, end, -refcnt); 104 } 105 106 /* 107 * Convert (or add) a range tree into a reference tree. 108 */ 109 void 110 space_reftree_add_map(avl_tree_t *t, range_tree_t *rt, int64_t refcnt) 111 { 112 range_seg_t *rs; 113 114 for (rs = avl_first(&rt->rt_root); rs; rs = AVL_NEXT(&rt->rt_root, rs)) 115 space_reftree_add_seg(t, rs->rs_start, rs->rs_end, refcnt); 116 } 117 118 /* 119 * Convert a reference tree into a range tree. The range tree will contain 120 * all members of the reference tree for which refcnt >= minref. 121 */ 122 void 123 space_reftree_generate_map(avl_tree_t *t, range_tree_t *rt, int64_t minref) 124 { 125 uint64_t start = -1ULL; 126 int64_t refcnt = 0; 127 space_ref_t *sr; 128 129 range_tree_vacate(rt, NULL, NULL); 130 131 for (sr = avl_first(t); sr != NULL; sr = AVL_NEXT(t, sr)) { 132 refcnt += sr->sr_refcnt; 133 if (refcnt >= minref) { 134 if (start == -1ULL) { 135 start = sr->sr_offset; 136 } 137 } else { 138 if (start != -1ULL) { 139 uint64_t end = sr->sr_offset; 140 ASSERT(start <= end); 141 if (end > start) 142 range_tree_add(rt, start, end - start); 143 start = -1ULL; 144 } 145 } 146 } 147 ASSERT(refcnt == 0); 148 ASSERT(start == -1ULL); 149 } 150