1#ifndef CEPH_CRUSH_CRUSH_H 2#define CEPH_CRUSH_CRUSH_H 3 4#ifdef __KERNEL__ 5# include <linux/rbtree.h> 6# include <linux/types.h> 7#else 8# include "crush_compat.h" 9#endif 10 11/* 12 * CRUSH is a pseudo-random data distribution algorithm that 13 * efficiently distributes input values (typically, data objects) 14 * across a heterogeneous, structured storage cluster. 15 * 16 * The algorithm was originally described in detail in this paper 17 * (although the algorithm has evolved somewhat since then): 18 * 19 * http://www.ssrc.ucsc.edu/Papers/weil-sc06.pdf 20 * 21 * LGPL2 22 */ 23 24 25#define CRUSH_MAGIC 0x00010000ul /* for detecting algorithm revisions */ 26 27#define CRUSH_MAX_DEPTH 10 /* max crush hierarchy depth */ 28#define CRUSH_MAX_RULESET (1<<8) /* max crush ruleset number */ 29#define CRUSH_MAX_RULES CRUSH_MAX_RULESET /* should be the same as max rulesets */ 30 31#define CRUSH_MAX_DEVICE_WEIGHT (100u * 0x10000u) 32#define CRUSH_MAX_BUCKET_WEIGHT (65535u * 0x10000u) 33 34#define CRUSH_ITEM_UNDEF 0x7ffffffe /* undefined result (internal use only) */ 35#define CRUSH_ITEM_NONE 0x7fffffff /* no result */ 36 37/* 38 * CRUSH uses user-defined "rules" to describe how inputs should be 39 * mapped to devices. A rule consists of sequence of steps to perform 40 * to generate the set of output devices. 41 */ 42struct crush_rule_step { 43 __u32 op; 44 __s32 arg1; 45 __s32 arg2; 46}; 47 48/* step op codes */ 49enum { 50 CRUSH_RULE_NOOP = 0, 51 CRUSH_RULE_TAKE = 1, /* arg1 = value to start with */ 52 CRUSH_RULE_CHOOSE_FIRSTN = 2, /* arg1 = num items to pick */ 53 /* arg2 = type */ 54 CRUSH_RULE_CHOOSE_INDEP = 3, /* same */ 55 CRUSH_RULE_EMIT = 4, /* no args */ 56 CRUSH_RULE_CHOOSELEAF_FIRSTN = 6, 57 CRUSH_RULE_CHOOSELEAF_INDEP = 7, 58 59 CRUSH_RULE_SET_CHOOSE_TRIES = 8, /* override choose_total_tries */ 60 CRUSH_RULE_SET_CHOOSELEAF_TRIES = 9, /* override chooseleaf_descend_once */ 61 CRUSH_RULE_SET_CHOOSE_LOCAL_TRIES = 10, 62 CRUSH_RULE_SET_CHOOSE_LOCAL_FALLBACK_TRIES = 11, 63 CRUSH_RULE_SET_CHOOSELEAF_VARY_R = 12, 64 CRUSH_RULE_SET_CHOOSELEAF_STABLE = 13 65}; 66 67/* 68 * for specifying choose num (arg1) relative to the max parameter 69 * passed to do_rule 70 */ 71#define CRUSH_CHOOSE_N 0 72#define CRUSH_CHOOSE_N_MINUS(x) (-(x)) 73 74/* 75 * The rule mask is used to describe what the rule is intended for. 76 * Given a ruleset and size of output set, we search through the 77 * rule list for a matching rule_mask. 78 */ 79struct crush_rule_mask { 80 __u8 ruleset; 81 __u8 type; 82 __u8 min_size; 83 __u8 max_size; 84}; 85 86struct crush_rule { 87 __u32 len; 88 struct crush_rule_mask mask; 89 struct crush_rule_step steps[0]; 90}; 91 92#define crush_rule_size(len) (sizeof(struct crush_rule) + \ 93 (len)*sizeof(struct crush_rule_step)) 94 95 96 97/* 98 * A bucket is a named container of other items (either devices or 99 * other buckets). Items within a bucket are chosen using one of a 100 * few different algorithms. The table summarizes how the speed of 101 * each option measures up against mapping stability when items are 102 * added or removed. 103 * 104 * Bucket Alg Speed Additions Removals 105 * ------------------------------------------------ 106 * uniform O(1) poor poor 107 * list O(n) optimal poor 108 * tree O(log n) good good 109 * straw O(n) better better 110 * straw2 O(n) optimal optimal 111 */ 112enum { 113 CRUSH_BUCKET_UNIFORM = 1, 114 CRUSH_BUCKET_LIST = 2, 115 CRUSH_BUCKET_TREE = 3, 116 CRUSH_BUCKET_STRAW = 4, 117 CRUSH_BUCKET_STRAW2 = 5, 118}; 119extern const char *crush_bucket_alg_name(int alg); 120 121/* 122 * although tree was a legacy algorithm, it has been buggy, so 123 * exclude it. 124 */ 125#define CRUSH_LEGACY_ALLOWED_BUCKET_ALGS ( \ 126 (1 << CRUSH_BUCKET_UNIFORM) | \ 127 (1 << CRUSH_BUCKET_LIST) | \ 128 (1 << CRUSH_BUCKET_STRAW)) 129 130struct crush_bucket { 131 __s32 id; /* this'll be negative */ 132 __u16 type; /* non-zero; type=0 is reserved for devices */ 133 __u8 alg; /* one of CRUSH_BUCKET_* */ 134 __u8 hash; /* which hash function to use, CRUSH_HASH_* */ 135 __u32 weight; /* 16-bit fixed point */ 136 __u32 size; /* num items */ 137 __s32 *items; 138 139}; 140 141/** @ingroup API 142 * 143 * Replacement weights for each item in a bucket. The size of the 144 * array must be exactly the size of the straw2 bucket, just as the 145 * item_weights array. 146 * 147 */ 148struct crush_weight_set { 149 __u32 *weights; /*!< 16.16 fixed point weights 150 in the same order as items */ 151 __u32 size; /*!< size of the __weights__ array */ 152}; 153 154/** @ingroup API 155 * 156 * Replacement weights and ids for a given straw2 bucket, for 157 * placement purposes. 158 * 159 * When crush_do_rule() chooses the Nth item from a straw2 bucket, the 160 * replacement weights found at __weight_set[N]__ are used instead of 161 * the weights from __item_weights__. If __N__ is greater than 162 * __weight_set_size__, the weights found at __weight_set_size-1__ are 163 * used instead. For instance if __weight_set__ is: 164 * 165 * [ [ 0x10000, 0x20000 ], // position 0 166 * [ 0x20000, 0x40000 ] ] // position 1 167 * 168 * choosing the 0th item will use position 0 weights [ 0x10000, 0x20000 ] 169 * choosing the 1th item will use position 1 weights [ 0x20000, 0x40000 ] 170 * choosing the 2th item will use position 1 weights [ 0x20000, 0x40000 ] 171 * etc. 172 * 173 */ 174struct crush_choose_arg { 175 __s32 *ids; /*!< values to use instead of items */ 176 __u32 ids_size; /*!< size of the __ids__ array */ 177 struct crush_weight_set *weight_set; /*!< weight replacements for 178 a given position */ 179 __u32 weight_set_size; /*!< size of the __weight_set__ array */ 180}; 181 182/** @ingroup API 183 * 184 * Replacement weights and ids for each bucket in the crushmap. The 185 * __size__ of the __args__ array must be exactly the same as the 186 * __map->max_buckets__. 187 * 188 * The __crush_choose_arg__ at index N will be used when choosing 189 * an item from the bucket __map->buckets[N]__ bucket, provided it 190 * is a straw2 bucket. 191 * 192 */ 193struct crush_choose_arg_map { 194#ifdef __KERNEL__ 195 struct rb_node node; 196 s64 choose_args_index; 197#endif 198 struct crush_choose_arg *args; /*!< replacement for each bucket 199 in the crushmap */ 200 __u32 size; /*!< size of the __args__ array */ 201}; 202 203struct crush_bucket_uniform { 204 struct crush_bucket h; 205 __u32 item_weight; /* 16-bit fixed point; all items equally weighted */ 206}; 207 208struct crush_bucket_list { 209 struct crush_bucket h; 210 __u32 *item_weights; /* 16-bit fixed point */ 211 __u32 *sum_weights; /* 16-bit fixed point. element i is sum 212 of weights 0..i, inclusive */ 213}; 214 215struct crush_bucket_tree { 216 struct crush_bucket h; /* note: h.size is _tree_ size, not number of 217 actual items */ 218 __u8 num_nodes; 219 __u32 *node_weights; 220}; 221 222struct crush_bucket_straw { 223 struct crush_bucket h; 224 __u32 *item_weights; /* 16-bit fixed point */ 225 __u32 *straws; /* 16-bit fixed point */ 226}; 227 228struct crush_bucket_straw2 { 229 struct crush_bucket h; 230 __u32 *item_weights; /* 16-bit fixed point */ 231}; 232 233 234 235/* 236 * CRUSH map includes all buckets, rules, etc. 237 */ 238struct crush_map { 239 struct crush_bucket **buckets; 240 struct crush_rule **rules; 241 242 __s32 max_buckets; 243 __u32 max_rules; 244 __s32 max_devices; 245 246 /* choose local retries before re-descent */ 247 __u32 choose_local_tries; 248 /* choose local attempts using a fallback permutation before 249 * re-descent */ 250 __u32 choose_local_fallback_tries; 251 /* choose attempts before giving up */ 252 __u32 choose_total_tries; 253 /* attempt chooseleaf inner descent once for firstn mode; on 254 * reject retry outer descent. Note that this does *not* 255 * apply to a collision: in that case we will retry as we used 256 * to. */ 257 __u32 chooseleaf_descend_once; 258 259 /* if non-zero, feed r into chooseleaf, bit-shifted right by (r-1) 260 * bits. a value of 1 is best for new clusters. for legacy clusters 261 * that want to limit reshuffling, a value of 3 or 4 will make the 262 * mappings line up a bit better with previous mappings. */ 263 __u8 chooseleaf_vary_r; 264 265 /* if true, it makes chooseleaf firstn to return stable results (if 266 * no local retry) so that data migrations would be optimal when some 267 * device fails. */ 268 __u8 chooseleaf_stable; 269 270 /* 271 * This value is calculated after decode or construction by 272 * the builder. It is exposed here (rather than having a 273 * 'build CRUSH working space' function) so that callers can 274 * reserve a static buffer, allocate space on the stack, or 275 * otherwise avoid calling into the heap allocator if they 276 * want to. The size of the working space depends on the map, 277 * while the size of the scratch vector passed to the mapper 278 * depends on the size of the desired result set. 279 * 280 * Nothing stops the caller from allocating both in one swell 281 * foop and passing in two points, though. 282 */ 283 size_t working_size; 284 285#ifndef __KERNEL__ 286 /* 287 * version 0 (original) of straw_calc has various flaws. version 1 288 * fixes a few of them. 289 */ 290 __u8 straw_calc_version; 291 292 /* 293 * allowed bucket algs is a bitmask, here the bit positions 294 * are CRUSH_BUCKET_*. note that these are *bits* and 295 * CRUSH_BUCKET_* values are not, so we need to or together (1 296 * << CRUSH_BUCKET_WHATEVER). The 0th bit is not used to 297 * minimize confusion (bucket type values start at 1). 298 */ 299 __u32 allowed_bucket_algs; 300 301 __u32 *choose_tries; 302#else 303 /* CrushWrapper::choose_args */ 304 struct rb_root choose_args; 305#endif 306}; 307 308 309/* crush.c */ 310extern int crush_get_bucket_item_weight(const struct crush_bucket *b, int pos); 311extern void crush_destroy_bucket_uniform(struct crush_bucket_uniform *b); 312extern void crush_destroy_bucket_list(struct crush_bucket_list *b); 313extern void crush_destroy_bucket_tree(struct crush_bucket_tree *b); 314extern void crush_destroy_bucket_straw(struct crush_bucket_straw *b); 315extern void crush_destroy_bucket_straw2(struct crush_bucket_straw2 *b); 316extern void crush_destroy_bucket(struct crush_bucket *b); 317extern void crush_destroy_rule(struct crush_rule *r); 318extern void crush_destroy(struct crush_map *map); 319 320static inline int crush_calc_tree_node(int i) 321{ 322 return ((i+1) << 1)-1; 323} 324 325/* 326 * These data structures are private to the CRUSH implementation. They 327 * are exposed in this header file because builder needs their 328 * definitions to calculate the total working size. 329 * 330 * Moving this out of the crush map allow us to treat the CRUSH map as 331 * immutable within the mapper and removes the requirement for a CRUSH 332 * map lock. 333 */ 334struct crush_work_bucket { 335 __u32 perm_x; /* @x for which *perm is defined */ 336 __u32 perm_n; /* num elements of *perm that are permuted/defined */ 337 __u32 *perm; /* Permutation of the bucket's items */ 338}; 339 340struct crush_work { 341 struct crush_work_bucket **work; /* Per-bucket working store */ 342}; 343 344#endif 345