1 /* 2 * Copyright (c) 2007 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * $DragonFly: src/sys/vfs/hammer/hammer_btree.h,v 1.24 2008/06/26 04:06:22 dillon Exp $ 35 */ 36 37 #ifndef VFS_HAMMER_BTREE_H_ 38 #define VFS_HAMMER_BTREE_H_ 39 40 /* 41 * HAMMER B-Tree index 42 * 43 * HAMMER implements a modified B+Tree. B+Trees store records only 44 * at their leaves and HAMMER's modification is to adjust the internal 45 * elements so there is a boundary element on each side instead of sub-tree 46 * pointers. 47 * 48 * We just call our modified B+Tree a 'B-Tree' in HAMMER documentation to 49 * reduce confusion. 50 * 51 * A B-Tree internal node looks like this: 52 * 53 * B N N N N N N B <-- boundary and internal elements 54 * S S S S S S S <-- subtree pointers 55 * 56 * A B-Tree leaf node looks like this: 57 * 58 * L L L L L L L L <-- leaf elemenets 59 * (there is also a previous and next-leaf pointer) 60 * 61 * The recursion radix of an internal node is reduced by 1 relative to 62 * a normal B-Tree in order to accomodate the right-hand boundary. 63 * The left-hand boundary (B in the left) is integrated into the first 64 * element so it doesn't require 2 elements to accomodate boundaries. 65 * 66 * The big benefit to using a B-Tree with built-in bounds information is 67 * that it makes it possible to cache pointers into the middle of the tree 68 * and not have to start searches, insertions, OR deletions at the root node. 69 * The boundary elements allow searches to progress in a definitive direction 70 * from any point in the tree without revisting nodes. It is also possible 71 * to terminate searches early and make minor adjustments to the boundaries 72 * (within the confines of the parent's boundaries) on the fly. This greatly 73 * improves the efficiency of many operations. 74 * 75 * All of the structures below are on-disk structures. 76 */ 77 78 /* 79 * Common base for all B-Tree element types (40 bytes) 80 * 81 * The following fields are keys used by hammer_btree_cmp() 82 * to compare B-Tree elements listed from higher priority 83 * to lower priority on comparison. 84 * 85 * 1. localization 86 * 2. obj_id 87 * 3. rec_type 88 * 4. key 89 * 5. create_id 90 */ 91 struct hammer_base_elm { 92 int64_t obj_id; /* 00 object record is associated with */ 93 int64_t key; /* 08 indexing key (offset or namekey) */ 94 95 hammer_tid_t create_tid; /* 10 transaction id for record creation */ 96 hammer_tid_t delete_tid; /* 18 transaction id for record update/del */ 97 98 u_int16_t rec_type; /* 20 _RECTYPE_ */ 99 u_int8_t obj_type; /* 22 _OBJTYPE_ (restricted) */ 100 u_int8_t btype; /* 23 B-Tree element type */ 101 u_int32_t localization; /* 24 B-Tree localization parameter */ 102 /* 28 */ 103 }; 104 105 typedef struct hammer_base_elm *hammer_base_elm_t; 106 107 /* 108 * Localization has sorting priority over the obj_id,rec_type,key,tid 109 * and is used to localize inodes for very fast directory scans. 110 * 111 * Localization can also be used to create pseudo-filesystems within 112 * a HAMMER filesystem. Pseudo-filesystems would be suitable 113 * replication targets. Upper 16 bits of the localization field in 114 * struct hammer_base_elm represents pseudo-filesystem id, and lower 115 * 16 bits of this field represents its type (inode or misc). 116 * 117 * The root inode (not the PFS root inode but the real root) uses 118 * HAMMER_DEF_LOCALIZATION for its incore ip->obj_localization. 119 * HAMMER_DEF_LOCALIZATION implies PFS 0 and no localization type. 120 */ 121 #define HAMMER_LOCALIZE_RESERVED00 0x00000000 122 #define HAMMER_LOCALIZE_INODE 0x00000001 123 #define HAMMER_LOCALIZE_MISC 0x00000002 124 #define HAMMER_LOCALIZE_RESERVED03 0x00000003 125 #define HAMMER_LOCALIZE_MASK 0x0000FFFF 126 #define HAMMER_LOCALIZE_PSEUDOFS_MASK 0xFFFF0000 127 128 #define HAMMER_MIN_LOCALIZATION 0x00000000U 129 #define HAMMER_MAX_LOCALIZATION 0x0000FFFFU 130 #define HAMMER_DEF_LOCALIZATION 0x00000000U 131 132 /* 133 * Internal element (40 + 24 = 64 bytes). 134 * 135 * An internal element contains a recursion to another B-Tree node. 136 */ 137 struct hammer_btree_internal_elm { 138 struct hammer_base_elm base; 139 hammer_tid_t mirror_tid; /* mirroring support */ 140 hammer_off_t subtree_offset; 141 int32_t unused02; 142 int32_t unused03; 143 }; 144 145 typedef struct hammer_btree_internal_elm *hammer_btree_internal_elm_t; 146 147 /* 148 * Leaf B-Tree element (40 + 24 = 64 bytes). 149 * 150 * NOTE: create_ts/delete_ts are not used by any core algorithms, they are 151 * used only by userland to present nominal real-time date strings 152 * to the user. 153 */ 154 struct hammer_btree_leaf_elm { 155 struct hammer_base_elm base; 156 u_int32_t create_ts; 157 u_int32_t delete_ts; 158 hammer_off_t data_offset; 159 int32_t data_len; 160 hammer_crc_t data_crc; 161 }; 162 163 typedef struct hammer_btree_leaf_elm *hammer_btree_leaf_elm_t; 164 165 /* 166 * Rollup btree leaf element types - 64 byte structure 167 */ 168 union hammer_btree_elm { 169 struct hammer_base_elm base; 170 struct hammer_btree_leaf_elm leaf; 171 struct hammer_btree_internal_elm internal; 172 }; 173 174 typedef union hammer_btree_elm *hammer_btree_elm_t; 175 176 /* 177 * B-Tree node (64x64 = 4K structure) 178 * 179 * Each node contains 63 elements. The last element for an internal node 180 * is the right-boundary so internal nodes have one fewer logical elements 181 * then leaf nodes. 182 * 183 * 'count' always refers to the number of elements and is non-inclusive of 184 * the right-hand boundary for an internal node. For a leaf node, 'count' 185 * refers to the number of elements and there is no idea of boundaries. 186 * 187 * The use of a fairly large radix is designed to reduce the number of 188 * discrete disk accesses required to locate something. Keep in mind 189 * that nodes are allocated out of 16K hammer buffers so supported values 190 * are (256-1), (128-1), (64-1), (32-1), or (16-1). HAMMER uses 63-way 191 * so the node size is (64x(1+(64-1))) = 4KB. 192 * 193 * NOTE: FUTURE EXPANSION: The reserved fields in hammer_node_ondisk are 194 * reserved for left/right leaf linkage fields, flags, and other future 195 * features. 196 */ 197 #define HAMMER_BTREE_LEAF_ELMS 63 198 #define HAMMER_BTREE_INT_ELMS (HAMMER_BTREE_LEAF_ELMS - 1) 199 200 #define HAMMER_BTREE_TYPE_INTERNAL ((u_int8_t)'I') 201 #define HAMMER_BTREE_TYPE_LEAF ((u_int8_t)'L') 202 #define HAMMER_BTREE_TYPE_RECORD ((u_int8_t)'R') 203 #define HAMMER_BTREE_TYPE_DELETED ((u_int8_t)'D') 204 #define HAMMER_BTREE_TYPE_NONE ((u_int8_t)0) 205 206 /* 207 * Return 1 if elm is a node element of an internal node, 208 * otherwise return 0. 209 */ 210 static __inline 211 int 212 hammer_is_internal_node_elm(hammer_btree_elm_t elm) 213 { 214 switch (elm->base.btype) { 215 case HAMMER_BTREE_TYPE_INTERNAL: 216 case HAMMER_BTREE_TYPE_LEAF: 217 return(1); 218 } 219 return(0); 220 } 221 222 /* 223 * Return 1 if elm is a node element of a leaf node, 224 * otherwise return 0. 225 */ 226 static __inline 227 int 228 hammer_is_leaf_node_elm(hammer_btree_elm_t elm) 229 { 230 switch (elm->base.btype) { 231 case HAMMER_BTREE_TYPE_RECORD: 232 return(1); 233 } 234 return(0); 235 } 236 237 static __inline 238 int 239 hammer_node_max_elements(u_int8_t type) 240 { 241 switch (type) { 242 case HAMMER_BTREE_TYPE_LEAF: 243 return(HAMMER_BTREE_LEAF_ELMS); 244 case HAMMER_BTREE_TYPE_INTERNAL: 245 return(HAMMER_BTREE_INT_ELMS); 246 } 247 return(-1); /* invalid type */ 248 } 249 250 static __inline 251 char 252 hammer_elm_btype(hammer_btree_elm_t elm) 253 { 254 switch(elm->base.btype) { 255 case HAMMER_BTREE_TYPE_INTERNAL: 256 case HAMMER_BTREE_TYPE_LEAF: 257 case HAMMER_BTREE_TYPE_RECORD: 258 case HAMMER_BTREE_TYPE_DELETED: 259 return(elm->base.btype); /* ascii */ 260 case HAMMER_BTREE_TYPE_NONE: 261 return('*'); 262 default: 263 return('?'); 264 } 265 } 266 267 struct hammer_node_ondisk { 268 /* 269 * B-Tree node header (64 bytes) 270 */ 271 hammer_crc_t crc; /* MUST BE FIRST FIELD OF STRUCTURE */ 272 u_int32_t signature; /* 0 or 0xB3A49586 but not used for anything */ 273 hammer_off_t parent; /* 0 if at root of B-Tree */ 274 int32_t count; 275 u_int8_t type; 276 u_int8_t reserved01; 277 u_int16_t reserved02; 278 hammer_off_t reserved03; /* future link_left */ 279 hammer_off_t reserved04; /* future link_right */ 280 hammer_off_t reserved05; 281 hammer_off_t reserved06; 282 hammer_tid_t mirror_tid; /* mirroring support (aggregator) */ 283 284 /* 285 * Element array. Internal nodes have one less logical element 286 * (meaning: the same number of physical elements) in order to 287 * accomodate the right-hand boundary. The left-hand boundary 288 * is integrated into the first element. Leaf nodes have no 289 * boundary elements. 290 */ 291 union hammer_btree_elm elms[HAMMER_BTREE_LEAF_ELMS]; 292 }; 293 294 #define HAMMER_BTREE_SIGNATURE_GOOD 0xB3A49586 295 #define HAMMER_BTREE_SIGNATURE_DESTROYED 0x4A3B2C1D /* not used */ 296 #define HAMMER_BTREE_CRCSIZE \ 297 (sizeof(struct hammer_node_ondisk) - sizeof(hammer_crc_t)) 298 299 typedef struct hammer_node_ondisk *hammer_node_ondisk_t; 300 301 #endif /* !VFS_HAMMER_BTREE_H_ */ 302