BRT should return EOPNOTSUPP
[zfs.git] / module / zfs / space_reftree.c
blobee11e162dd5ba9311909ddf4829241bb0bc69911
1 /*
2 * CDDL HEADER START
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.
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or https://opensource.org/licenses/CDDL-1.0.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
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]
19 * CDDL HEADER END
22 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
26 * Copyright (c) 2013, 2019 by Delphix. All rights reserved.
29 #include <sys/zfs_context.h>
30 #include <sys/range_tree.h>
31 #include <sys/space_reftree.h>
34 * Space reference trees.
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.
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.]
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.
54 static int
55 space_reftree_compare(const void *x1, const void *x2)
57 const space_ref_t *sr1 = (const space_ref_t *)x1;
58 const space_ref_t *sr2 = (const space_ref_t *)x2;
60 int cmp = TREE_CMP(sr1->sr_offset, sr2->sr_offset);
61 if (likely(cmp))
62 return (cmp);
64 return (TREE_PCMP(sr1, sr2));
67 void
68 space_reftree_create(avl_tree_t *t)
70 avl_create(t, space_reftree_compare,
71 sizeof (space_ref_t), offsetof(space_ref_t, sr_node));
74 void
75 space_reftree_destroy(avl_tree_t *t)
77 space_ref_t *sr;
78 void *cookie = NULL;
80 while ((sr = avl_destroy_nodes(t, &cookie)) != NULL)
81 kmem_free(sr, sizeof (*sr));
83 avl_destroy(t);
86 static void
87 space_reftree_add_node(avl_tree_t *t, uint64_t offset, int64_t refcnt)
89 space_ref_t *sr;
91 sr = kmem_alloc(sizeof (*sr), KM_SLEEP);
92 sr->sr_offset = offset;
93 sr->sr_refcnt = refcnt;
95 avl_add(t, sr);
98 void
99 space_reftree_add_seg(avl_tree_t *t, uint64_t start, uint64_t end,
100 int64_t refcnt)
102 space_reftree_add_node(t, start, refcnt);
103 space_reftree_add_node(t, end, -refcnt);
107 * Convert (or add) a range tree into a reference tree.
109 void
110 space_reftree_add_map(avl_tree_t *t, range_tree_t *rt, int64_t refcnt)
112 zfs_btree_index_t where;
114 for (range_seg_t *rs = zfs_btree_first(&rt->rt_root, &where); rs; rs =
115 zfs_btree_next(&rt->rt_root, &where, &where)) {
116 space_reftree_add_seg(t, rs_get_start(rs, rt), rs_get_end(rs,
117 rt), refcnt);
122 * Convert a reference tree into a range tree. The range tree will contain
123 * all members of the reference tree for which refcnt >= minref.
125 void
126 space_reftree_generate_map(avl_tree_t *t, range_tree_t *rt, int64_t minref)
128 uint64_t start = -1ULL;
129 int64_t refcnt = 0;
130 space_ref_t *sr;
132 range_tree_vacate(rt, NULL, NULL);
134 for (sr = avl_first(t); sr != NULL; sr = AVL_NEXT(t, sr)) {
135 refcnt += sr->sr_refcnt;
136 if (refcnt >= minref) {
137 if (start == -1ULL) {
138 start = sr->sr_offset;
140 } else {
141 if (start != -1ULL) {
142 uint64_t end = sr->sr_offset;
143 ASSERT(start <= end);
144 if (end > start)
145 range_tree_add(rt, start, end - start);
146 start = -1ULL;
150 ASSERT(refcnt == 0);
151 ASSERT(start == -1ULL);