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 /*
27 * Copyright (c) 2013 by Delphix. All rights reserved.
28 */
29
30 #ifndef _SYS_METASLAB_IMPL_H
31 #define _SYS_METASLAB_IMPL_H
32
33 #include <sys/metaslab.h>
34 #include <sys/space_map.h>
35 #include <sys/range_tree.h>
36 #include <sys/vdev.h>
37 #include <sys/txg.h>
38 #include <sys/avl.h>
39
40 #ifdef __cplusplus
41 extern "C" {
42 #endif
43
44 struct metaslab_class {
45 spa_t *mc_spa;
46 metaslab_group_t *mc_rotor;
47 metaslab_ops_t *mc_ops;
48 uint64_t mc_aliquot;
49 uint64_t mc_alloc_groups; /* # of allocatable groups */
50 uint64_t mc_alloc; /* total allocated space */
51 uint64_t mc_deferred; /* total deferred frees */
52 uint64_t mc_space; /* total space (alloc + free) */
53 uint64_t mc_dspace; /* total deflated space */
54 };
55
56 struct metaslab_group {
57 kmutex_t mg_lock;
58 avl_tree_t mg_metaslab_tree;
59 uint64_t mg_aliquot;
60 uint64_t mg_alloc_failures;
61 boolean_t mg_allocatable; /* can we allocate? */
62 uint64_t mg_free_capacity; /* percentage free */
63 int64_t mg_bias;
64 int64_t mg_activation_count;
65 metaslab_class_t *mg_class;
66 vdev_t *mg_vd;
67 taskq_t *mg_taskq;
68 metaslab_group_t *mg_prev;
69 metaslab_group_t *mg_next;
70 };
71
72 /*
73 * This value defines the number of elements in the ms_lbas array. The value
74 * of 64 was chosen as it covers to cover all power of 2 buckets up to
75 * UINT64_MAX. This is the equivalent of highbit(UINT64_MAX).
76 */
77 #define MAX_LBAS 64
78
79 /*
80 * Each metaslab maintains a set of in-core trees to track metaslab operations.
81 * The in-core free tree (ms_tree) contains the current list of free segments.
82 * As blocks are allocated, the allocated segment are removed from the ms_tree
83 * and added to a per txg allocation tree (ms_alloctree). As blocks are freed,
84 * they are added to the per txg free tree (ms_freetree). These per txg
85 * trees allow us to process all allocations and frees in syncing context
86 * where it is safe to update the on-disk space maps. One additional in-core
87 * tree is maintained to track deferred frees (ms_defertree). Once a block
88 * is freed it will move from the ms_freetree to the ms_defertree. A deferred
89 * free means that a block has been freed but cannot be used by the pool
90 * until TXG_DEFER_SIZE transactions groups later. For example, a block
91 * that is freed in txg 50 will not be available for reallocation until
92 * txg 52 (50 + TXG_DEFER_SIZE). This provides a safety net for uberblock
93 * rollback. A pool could be safely rolled back TXG_DEFERS_SIZE
94 * transactions groups and ensure that no block has been reallocated.
95 *
96 * The simplified transition diagram looks like this:
97 *
98 *
99 * ALLOCATE
100 * |
101 * V
102 * free segment (ms_tree) --------> ms_alloctree ----> (write to space map)
103 * ^
104 * |
105 * | ms_freetree <--- FREE
106 * | |
107 * | |
108 * | |
109 * +----------- ms_defertree <-------+---------> (write to space map)
110 *
111 *
112 * Each metaslab's space is tracked in a single space map in the MOS,
113 * which is only updated in syncing context. Each time we sync a txg,
114 * we append the allocs and frees from that txg to the space map.
115 * The pool space is only updated once all metaslabs have finished syncing.
116 *
117 * To load the in-core free tree we read the space map from disk.
118 * This object contains a series of alloc and free records that are
119 * combined to make up the list of all free segments in this metaslab. These
120 * segments are represented in-core by the ms_tree and are stored in an
121 * AVL tree.
122 *
123 * As the space map grows (as a result of the appends) it will
124 * eventually become space-inefficient. When the metaslab's in-core free tree
125 * is zfs_condense_pct/100 times the size of the minimal on-disk
126 * representation, we rewrite it in its minimized form. If a metaslab
127 * needs to condense then we must set the ms_condensing flag to ensure
128 * that allocations are not performed on the metaslab that is being written.
129 */
130 struct metaslab {
131 kmutex_t ms_lock;
132 kcondvar_t ms_load_cv;
133 space_map_t *ms_sm;
134 metaslab_ops_t *ms_ops;
135 uint64_t ms_id;
136 uint64_t ms_start;
137 uint64_t ms_size;
138
139 range_tree_t *ms_alloctree[TXG_SIZE];
140 range_tree_t *ms_freetree[TXG_SIZE];
141 range_tree_t *ms_defertree[TXG_DEFER_SIZE];
142 range_tree_t *ms_tree;
143
144 boolean_t ms_condensing; /* condensing? */
145 boolean_t ms_loaded;
146 boolean_t ms_loading;
147
148 int64_t ms_deferspace; /* sum of ms_defermap[] space */
149 uint64_t ms_weight; /* weight vs. others in group */
150 uint64_t ms_factor;
151 uint64_t ms_access_txg;
152
153 /*
154 * The metaslab block allocators can optionally use a size-ordered
155 * range tree and/or an array of LBAs. Not all allocators use
156 * this functionality. The ms_size_tree should always contain the
157 * same number of segments as the ms_tree. The only difference
158 * is that the ms_size_tree is ordered by segment sizes.
159 */
160 avl_tree_t ms_size_tree;
161 uint64_t ms_lbas[MAX_LBAS];
162
163 metaslab_group_t *ms_group; /* metaslab group */
164 avl_node_t ms_group_node; /* node in metaslab group tree */
165 txg_node_t ms_txg_node; /* per-txg dirty metaslab links */
166 };
167
168 #ifdef __cplusplus
169 }
170 #endif
171
172 #endif /* _SYS_METASLAB_IMPL_H */