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) 2011, 2014 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 boolean_t mg_allocatable; /* can we allocate? */ 61 uint64_t mg_free_capacity; /* percentage free */ 62 int64_t mg_bias; 63 int64_t mg_activation_count; 64 metaslab_class_t *mg_class; 65 vdev_t *mg_vd; 66 taskq_t *mg_taskq; 67 metaslab_group_t *mg_prev; 68 metaslab_group_t *mg_next; 69 }; 70 71 /* 72 * This value defines the number of elements in the ms_lbas array. The value 73 * of 64 was chosen as it covers to cover all power of 2 buckets up to 74 * UINT64_MAX. This is the equivalent of highbit(UINT64_MAX). 75 */ 76 #define MAX_LBAS 64 77 78 /* 79 * Each metaslab maintains a set of in-core trees to track metaslab operations. 80 * The in-core free tree (ms_tree) contains the current list of free segments. 81 * As blocks are allocated, the allocated segment are removed from the ms_tree 82 * and added to a per txg allocation tree (ms_alloctree). As blocks are freed, 83 * they are added to the per txg free tree (ms_freetree). These per txg 84 * trees allow us to process all allocations and frees in syncing context 85 * where it is safe to update the on-disk space maps. One additional in-core 86 * tree is maintained to track deferred frees (ms_defertree). Once a block 87 * is freed it will move from the ms_freetree to the ms_defertree. A deferred 88 * free means that a block has been freed but cannot be used by the pool 89 * until TXG_DEFER_SIZE transactions groups later. For example, a block 90 * that is freed in txg 50 will not be available for reallocation until 91 * txg 52 (50 + TXG_DEFER_SIZE). This provides a safety net for uberblock 92 * rollback. A pool could be safely rolled back TXG_DEFERS_SIZE 93 * transactions groups and ensure that no block has been reallocated. 94 * 95 * The simplified transition diagram looks like this: 96 * 97 * 98 * ALLOCATE 99 * | 100 * V 101 * free segment (ms_tree) --------> ms_alloctree ----> (write to space map) 102 * ^ 103 * | 104 * | ms_freetree <--- FREE 105 * | | 106 * | | 107 * | | 108 * +----------- ms_defertree <-------+---------> (write to space map) 109 * 110 * 111 * Each metaslab's space is tracked in a single space map in the MOS, 112 * which is only updated in syncing context. Each time we sync a txg, 113 * we append the allocs and frees from that txg to the space map. 114 * The pool space is only updated once all metaslabs have finished syncing. 115 * 116 * To load the in-core free tree we read the space map from disk. 117 * This object contains a series of alloc and free records that are 118 * combined to make up the list of all free segments in this metaslab. These 119 * segments are represented in-core by the ms_tree and are stored in an 120 * AVL tree. 121 * 122 * As the space map grows (as a result of the appends) it will 123 * eventually become space-inefficient. When the metaslab's in-core free tree 124 * is zfs_condense_pct/100 times the size of the minimal on-disk 125 * representation, we rewrite it in its minimized form. If a metaslab 126 * needs to condense then we must set the ms_condensing flag to ensure 127 * that allocations are not performed on the metaslab that is being written. 128 */ 129 struct metaslab { 130 kmutex_t ms_lock; 131 kcondvar_t ms_load_cv; 132 space_map_t *ms_sm; 133 metaslab_ops_t *ms_ops; 134 uint64_t ms_id; 135 uint64_t ms_start; 136 uint64_t ms_size; 137 138 range_tree_t *ms_alloctree[TXG_SIZE]; 139 range_tree_t *ms_freetree[TXG_SIZE]; 140 range_tree_t *ms_defertree[TXG_DEFER_SIZE]; 141 range_tree_t *ms_tree; 142 143 boolean_t ms_condensing; /* condensing? */ 144 boolean_t ms_loaded; 145 boolean_t ms_loading; 146 147 int64_t ms_deferspace; /* sum of ms_defermap[] space */ 148 uint64_t ms_weight; /* weight vs. others in group */ 149 uint64_t ms_factor; 150 uint64_t ms_access_txg; 151 152 /* 153 * The metaslab block allocators can optionally use a size-ordered 154 * range tree and/or an array of LBAs. Not all allocators use 155 * this functionality. The ms_size_tree should always contain the 156 * same number of segments as the ms_tree. The only difference 157 * is that the ms_size_tree is ordered by segment sizes. 158 */ 159 avl_tree_t ms_size_tree; 160 uint64_t ms_lbas[MAX_LBAS]; 161 162 metaslab_group_t *ms_group; /* metaslab group */ 163 avl_node_t ms_group_node; /* node in metaslab group tree */ 164 txg_node_t ms_txg_node; /* per-txg dirty metaslab links */ 165 }; 166 167 #ifdef __cplusplus 168 } 169 #endif 170 171 #endif /* _SYS_METASLAB_IMPL_H */ 172