1 2 #ifdef __KERNEL__ 3 # include <linux/string.h> 4 # include <linux/slab.h> 5 # include <linux/bug.h> 6 # include <linux/kernel.h> 7 # ifndef dprintk 8 # define dprintk(args...) 9 # endif 10 #else 11 # include <string.h> 12 # include <stdio.h> 13 # include <stdlib.h> 14 # include <assert.h> 15 # define BUG_ON(x) assert(!(x)) 16 # define dprintk(args...) /* printf(args) */ 17 # define kmalloc(x, f) malloc(x) 18 # define kfree(x) free(x) 19 #endif 20 21 #include <linux/crush/crush.h> 22 #include <linux/crush/hash.h> 23 #include <linux/crush/mapper.h> 24 25 /* 26 * Implement the core CRUSH mapping algorithm. 27 */ 28 29 /** 30 * crush_find_rule - find a crush_rule id for a given ruleset, type, and size. 31 * @map: the crush_map 32 * @ruleset: the storage ruleset id (user defined) 33 * @type: storage ruleset type (user defined) 34 * @size: output set size 35 */ 36 int crush_find_rule(const struct crush_map *map, int ruleset, int type, int size) 37 { 38 __u32 i; 39 40 for (i = 0; i < map->max_rules; i++) { 41 if (map->rules[i] && 42 map->rules[i]->mask.ruleset == ruleset && 43 map->rules[i]->mask.type == type && 44 map->rules[i]->mask.min_size <= size && 45 map->rules[i]->mask.max_size >= size) 46 return i; 47 } 48 return -1; 49 } 50 51 52 /* 53 * bucket choose methods 54 * 55 * For each bucket algorithm, we have a "choose" method that, given a 56 * crush input @x and replica position (usually, position in output set) @r, 57 * will produce an item in the bucket. 58 */ 59 60 /* 61 * Choose based on a random permutation of the bucket. 62 * 63 * We used to use some prime number arithmetic to do this, but it 64 * wasn't very random, and had some other bad behaviors. Instead, we 65 * calculate an actual random permutation of the bucket members. 66 * Since this is expensive, we optimize for the r=0 case, which 67 * captures the vast majority of calls. 68 */ 69 static int bucket_perm_choose(struct crush_bucket *bucket, 70 int x, int r) 71 { 72 unsigned int pr = r % bucket->size; 73 unsigned int i, s; 74 75 /* start a new permutation if @x has changed */ 76 if (bucket->perm_x != (__u32)x || bucket->perm_n == 0) { 77 dprintk("bucket %d new x=%d\n", bucket->id, x); 78 bucket->perm_x = x; 79 80 /* optimize common r=0 case */ 81 if (pr == 0) { 82 s = crush_hash32_3(bucket->hash, x, bucket->id, 0) % 83 bucket->size; 84 bucket->perm[0] = s; 85 bucket->perm_n = 0xffff; /* magic value, see below */ 86 goto out; 87 } 88 89 for (i = 0; i < bucket->size; i++) 90 bucket->perm[i] = i; 91 bucket->perm_n = 0; 92 } else if (bucket->perm_n == 0xffff) { 93 /* clean up after the r=0 case above */ 94 for (i = 1; i < bucket->size; i++) 95 bucket->perm[i] = i; 96 bucket->perm[bucket->perm[0]] = 0; 97 bucket->perm_n = 1; 98 } 99 100 /* calculate permutation up to pr */ 101 for (i = 0; i < bucket->perm_n; i++) 102 dprintk(" perm_choose have %d: %d\n", i, bucket->perm[i]); 103 while (bucket->perm_n <= pr) { 104 unsigned int p = bucket->perm_n; 105 /* no point in swapping the final entry */ 106 if (p < bucket->size - 1) { 107 i = crush_hash32_3(bucket->hash, x, bucket->id, p) % 108 (bucket->size - p); 109 if (i) { 110 unsigned int t = bucket->perm[p + i]; 111 bucket->perm[p + i] = bucket->perm[p]; 112 bucket->perm[p] = t; 113 } 114 dprintk(" perm_choose swap %d with %d\n", p, p+i); 115 } 116 bucket->perm_n++; 117 } 118 for (i = 0; i < bucket->size; i++) 119 dprintk(" perm_choose %d: %d\n", i, bucket->perm[i]); 120 121 s = bucket->perm[pr]; 122 out: 123 dprintk(" perm_choose %d sz=%d x=%d r=%d (%d) s=%d\n", bucket->id, 124 bucket->size, x, r, pr, s); 125 return bucket->items[s]; 126 } 127 128 /* uniform */ 129 static int bucket_uniform_choose(struct crush_bucket_uniform *bucket, 130 int x, int r) 131 { 132 return bucket_perm_choose(&bucket->h, x, r); 133 } 134 135 /* list */ 136 static int bucket_list_choose(struct crush_bucket_list *bucket, 137 int x, int r) 138 { 139 int i; 140 141 for (i = bucket->h.size-1; i >= 0; i--) { 142 __u64 w = crush_hash32_4(bucket->h.hash,x, bucket->h.items[i], 143 r, bucket->h.id); 144 w &= 0xffff; 145 dprintk("list_choose i=%d x=%d r=%d item %d weight %x " 146 "sw %x rand %llx", 147 i, x, r, bucket->h.items[i], bucket->item_weights[i], 148 bucket->sum_weights[i], w); 149 w *= bucket->sum_weights[i]; 150 w = w >> 16; 151 /*dprintk(" scaled %llx\n", w);*/ 152 if (w < bucket->item_weights[i]) 153 return bucket->h.items[i]; 154 } 155 156 dprintk("bad list sums for bucket %d\n", bucket->h.id); 157 return bucket->h.items[0]; 158 } 159 160 161 /* (binary) tree */ 162 static int height(int n) 163 { 164 int h = 0; 165 while ((n & 1) == 0) { 166 h++; 167 n = n >> 1; 168 } 169 return h; 170 } 171 172 static int left(int x) 173 { 174 int h = height(x); 175 return x - (1 << (h-1)); 176 } 177 178 static int right(int x) 179 { 180 int h = height(x); 181 return x + (1 << (h-1)); 182 } 183 184 static int terminal(int x) 185 { 186 return x & 1; 187 } 188 189 static int bucket_tree_choose(struct crush_bucket_tree *bucket, 190 int x, int r) 191 { 192 int n, l; 193 __u32 w; 194 __u64 t; 195 196 /* start at root */ 197 n = bucket->num_nodes >> 1; 198 199 while (!terminal(n)) { 200 /* pick point in [0, w) */ 201 w = bucket->node_weights[n]; 202 t = (__u64)crush_hash32_4(bucket->h.hash, x, n, r, 203 bucket->h.id) * (__u64)w; 204 t = t >> 32; 205 206 /* descend to the left or right? */ 207 l = left(n); 208 if (t < bucket->node_weights[l]) 209 n = l; 210 else 211 n = right(n); 212 } 213 214 return bucket->h.items[n >> 1]; 215 } 216 217 218 /* straw */ 219 220 static int bucket_straw_choose(struct crush_bucket_straw *bucket, 221 int x, int r) 222 { 223 __u32 i; 224 int high = 0; 225 __u64 high_draw = 0; 226 __u64 draw; 227 228 for (i = 0; i < bucket->h.size; i++) { 229 draw = crush_hash32_3(bucket->h.hash, x, bucket->h.items[i], r); 230 draw &= 0xffff; 231 draw *= bucket->straws[i]; 232 if (i == 0 || draw > high_draw) { 233 high = i; 234 high_draw = draw; 235 } 236 } 237 return bucket->h.items[high]; 238 } 239 240 static int crush_bucket_choose(struct crush_bucket *in, int x, int r) 241 { 242 dprintk(" crush_bucket_choose %d x=%d r=%d\n", in->id, x, r); 243 BUG_ON(in->size == 0); 244 switch (in->alg) { 245 case CRUSH_BUCKET_UNIFORM: 246 return bucket_uniform_choose((struct crush_bucket_uniform *)in, 247 x, r); 248 case CRUSH_BUCKET_LIST: 249 return bucket_list_choose((struct crush_bucket_list *)in, 250 x, r); 251 case CRUSH_BUCKET_TREE: 252 return bucket_tree_choose((struct crush_bucket_tree *)in, 253 x, r); 254 case CRUSH_BUCKET_STRAW: 255 return bucket_straw_choose((struct crush_bucket_straw *)in, 256 x, r); 257 default: 258 dprintk("unknown bucket %d alg %d\n", in->id, in->alg); 259 return in->items[0]; 260 } 261 } 262 263 /* 264 * true if device is marked "out" (failed, fully offloaded) 265 * of the cluster 266 */ 267 static int is_out(const struct crush_map *map, const __u32 *weight, int item, int x) 268 { 269 if (weight[item] >= 0x10000) 270 return 0; 271 if (weight[item] == 0) 272 return 1; 273 if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff) 274 < weight[item]) 275 return 0; 276 return 1; 277 } 278 279 /** 280 * crush_choose - choose numrep distinct items of given type 281 * @map: the crush_map 282 * @bucket: the bucket we are choose an item from 283 * @x: crush input value 284 * @numrep: the number of items to choose 285 * @type: the type of item to choose 286 * @out: pointer to output vector 287 * @outpos: our position in that vector 288 * @firstn: true if choosing "first n" items, false if choosing "indep" 289 * @recurse_to_leaf: true if we want one device under each item of given type 290 * @out2: second output vector for leaf items (if @recurse_to_leaf) 291 */ 292 static int crush_choose(const struct crush_map *map, 293 struct crush_bucket *bucket, 294 const __u32 *weight, 295 int x, int numrep, int type, 296 int *out, int outpos, 297 int firstn, int recurse_to_leaf, 298 int *out2) 299 { 300 int rep; 301 unsigned int ftotal, flocal; 302 int retry_descent, retry_bucket, skip_rep; 303 struct crush_bucket *in = bucket; 304 int r; 305 int i; 306 int item = 0; 307 int itemtype; 308 int collide, reject; 309 const unsigned int orig_tries = 5; /* attempts before we fall back to search */ 310 311 dprintk("CHOOSE%s bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "", 312 bucket->id, x, outpos, numrep); 313 314 for (rep = outpos; rep < numrep; rep++) { 315 /* keep trying until we get a non-out, non-colliding item */ 316 ftotal = 0; 317 skip_rep = 0; 318 do { 319 retry_descent = 0; 320 in = bucket; /* initial bucket */ 321 322 /* choose through intervening buckets */ 323 flocal = 0; 324 do { 325 collide = 0; 326 retry_bucket = 0; 327 r = rep; 328 if (in->alg == CRUSH_BUCKET_UNIFORM) { 329 /* be careful */ 330 if (firstn || (__u32)numrep >= in->size) 331 /* r' = r + f_total */ 332 r += ftotal; 333 else if (in->size % numrep == 0) 334 /* r'=r+(n+1)*f_local */ 335 r += (numrep+1) * 336 (flocal+ftotal); 337 else 338 /* r' = r + n*f_local */ 339 r += numrep * (flocal+ftotal); 340 } else { 341 if (firstn) 342 /* r' = r + f_total */ 343 r += ftotal; 344 else 345 /* r' = r + n*f_local */ 346 r += numrep * (flocal+ftotal); 347 } 348 349 /* bucket choose */ 350 if (in->size == 0) { 351 reject = 1; 352 goto reject; 353 } 354 if (flocal >= (in->size>>1) && 355 flocal > orig_tries) 356 item = bucket_perm_choose(in, x, r); 357 else 358 item = crush_bucket_choose(in, x, r); 359 if (item >= map->max_devices) { 360 dprintk(" bad item %d\n", item); 361 skip_rep = 1; 362 break; 363 } 364 365 /* desired type? */ 366 if (item < 0) 367 itemtype = map->buckets[-1-item]->type; 368 else 369 itemtype = 0; 370 dprintk(" item %d type %d\n", item, itemtype); 371 372 /* keep going? */ 373 if (itemtype != type) { 374 if (item >= 0 || 375 (-1-item) >= map->max_buckets) { 376 dprintk(" bad item type %d\n", type); 377 skip_rep = 1; 378 break; 379 } 380 in = map->buckets[-1-item]; 381 retry_bucket = 1; 382 continue; 383 } 384 385 /* collision? */ 386 for (i = 0; i < outpos; i++) { 387 if (out[i] == item) { 388 collide = 1; 389 break; 390 } 391 } 392 393 reject = 0; 394 if (recurse_to_leaf) { 395 if (item < 0) { 396 if (crush_choose(map, 397 map->buckets[-1-item], 398 weight, 399 x, outpos+1, 0, 400 out2, outpos, 401 firstn, 0, 402 NULL) <= outpos) 403 /* didn't get leaf */ 404 reject = 1; 405 } else { 406 /* we already have a leaf! */ 407 out2[outpos] = item; 408 } 409 } 410 411 if (!reject) { 412 /* out? */ 413 if (itemtype == 0) 414 reject = is_out(map, weight, 415 item, x); 416 else 417 reject = 0; 418 } 419 420 reject: 421 if (reject || collide) { 422 ftotal++; 423 flocal++; 424 425 if (collide && flocal < 3) 426 /* retry locally a few times */ 427 retry_bucket = 1; 428 else if (flocal <= in->size + orig_tries) 429 /* exhaustive bucket search */ 430 retry_bucket = 1; 431 else if (ftotal < 20) 432 /* then retry descent */ 433 retry_descent = 1; 434 else 435 /* else give up */ 436 skip_rep = 1; 437 dprintk(" reject %d collide %d " 438 "ftotal %u flocal %u\n", 439 reject, collide, ftotal, 440 flocal); 441 } 442 } while (retry_bucket); 443 } while (retry_descent); 444 445 if (skip_rep) { 446 dprintk("skip rep\n"); 447 continue; 448 } 449 450 dprintk("CHOOSE got %d\n", item); 451 out[outpos] = item; 452 outpos++; 453 } 454 455 dprintk("CHOOSE returns %d\n", outpos); 456 return outpos; 457 } 458 459 460 /** 461 * crush_do_rule - calculate a mapping with the given input and rule 462 * @map: the crush_map 463 * @ruleno: the rule id 464 * @x: hash input 465 * @result: pointer to result vector 466 * @result_max: maximum result size 467 */ 468 int crush_do_rule(const struct crush_map *map, 469 int ruleno, int x, int *result, int result_max, 470 const __u32 *weight) 471 { 472 int result_len; 473 int a[CRUSH_MAX_SET]; 474 int b[CRUSH_MAX_SET]; 475 int c[CRUSH_MAX_SET]; 476 int recurse_to_leaf; 477 int *w; 478 int wsize = 0; 479 int *o; 480 int osize; 481 int *tmp; 482 struct crush_rule *rule; 483 __u32 step; 484 int i, j; 485 int numrep; 486 int firstn; 487 488 if ((__u32)ruleno >= map->max_rules) { 489 dprintk(" bad ruleno %d\n", ruleno); 490 return 0; 491 } 492 493 rule = map->rules[ruleno]; 494 result_len = 0; 495 w = a; 496 o = b; 497 498 for (step = 0; step < rule->len; step++) { 499 struct crush_rule_step *curstep = &rule->steps[step]; 500 501 firstn = 0; 502 switch (curstep->op) { 503 case CRUSH_RULE_TAKE: 504 w[0] = curstep->arg1; 505 wsize = 1; 506 break; 507 508 case CRUSH_RULE_CHOOSE_LEAF_FIRSTN: 509 case CRUSH_RULE_CHOOSE_FIRSTN: 510 firstn = 1; 511 /* fall through */ 512 case CRUSH_RULE_CHOOSE_LEAF_INDEP: 513 case CRUSH_RULE_CHOOSE_INDEP: 514 if (wsize == 0) 515 break; 516 517 recurse_to_leaf = 518 curstep->op == 519 CRUSH_RULE_CHOOSE_LEAF_FIRSTN || 520 curstep->op == 521 CRUSH_RULE_CHOOSE_LEAF_INDEP; 522 523 /* reset output */ 524 osize = 0; 525 526 for (i = 0; i < wsize; i++) { 527 /* 528 * see CRUSH_N, CRUSH_N_MINUS macros. 529 * basically, numrep <= 0 means relative to 530 * the provided result_max 531 */ 532 numrep = curstep->arg1; 533 if (numrep <= 0) { 534 numrep += result_max; 535 if (numrep <= 0) 536 continue; 537 } 538 j = 0; 539 osize += crush_choose(map, 540 map->buckets[-1-w[i]], 541 weight, 542 x, numrep, 543 curstep->arg2, 544 o+osize, j, 545 firstn, 546 recurse_to_leaf, c+osize); 547 } 548 549 if (recurse_to_leaf) 550 /* copy final _leaf_ values to output set */ 551 memcpy(o, c, osize*sizeof(*o)); 552 553 /* swap t and w arrays */ 554 tmp = o; 555 o = w; 556 w = tmp; 557 wsize = osize; 558 break; 559 560 561 case CRUSH_RULE_EMIT: 562 for (i = 0; i < wsize && result_len < result_max; i++) { 563 result[result_len] = w[i]; 564 result_len++; 565 } 566 wsize = 0; 567 break; 568 569 default: 570 dprintk(" unknown op %d at step %d\n", 571 curstep->op, step); 572 break; 573 } 574 } 575 return result_len; 576 } 577 578 579