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93cf2076 GW |
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 | /* | |
e9aa730c | 26 | * Copyright (c) 2013, 2015 by Delphix. All rights reserved. |
93cf2076 GW |
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 | { | |
ee36c709 GN |
57 | const space_ref_t *sr1 = (const space_ref_t *)x1; |
58 | const space_ref_t *sr2 = (const space_ref_t *)x2; | |
93cf2076 | 59 | |
ee36c709 GN |
60 | int cmp = AVL_CMP(sr1->sr_offset, sr2->sr_offset); |
61 | if (likely(cmp)) | |
62 | return (cmp); | |
93cf2076 | 63 | |
ee36c709 | 64 | return (AVL_PCMP(sr1, sr2)); |
93cf2076 GW |
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 | ||
79c76d5b | 91 | sr = kmem_alloc(sizeof (*sr), KM_SLEEP); |
93cf2076 GW |
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, | |
e9aa730c | 100 | int64_t refcnt) |
93cf2076 GW |
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 | ASSERT(MUTEX_HELD(rt->rt_lock)); | |
115 | ||
116 | for (rs = avl_first(&rt->rt_root); rs; rs = AVL_NEXT(&rt->rt_root, rs)) | |
117 | space_reftree_add_seg(t, rs->rs_start, rs->rs_end, refcnt); | |
118 | } | |
119 | ||
120 | /* | |
121 | * Convert a reference tree into a range tree. The range tree will contain | |
122 | * all members of the reference tree for which refcnt >= minref. | |
123 | */ | |
124 | void | |
125 | space_reftree_generate_map(avl_tree_t *t, range_tree_t *rt, int64_t minref) | |
126 | { | |
127 | uint64_t start = -1ULL; | |
128 | int64_t refcnt = 0; | |
129 | space_ref_t *sr; | |
130 | ||
131 | ASSERT(MUTEX_HELD(rt->rt_lock)); | |
132 | ||
133 | 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 | range_tree_add(rt, start, end - start); | |
147 | start = -1ULL; | |
148 | } | |
149 | } | |
150 | } | |
151 | ASSERT(refcnt == 0); | |
152 | ASSERT(start == -1ULL); | |
153 | } |