1 /* 2 * Ceph - scalable distributed file system 3 * 4 * Copyright (C) 2015 Intel Corporation All Rights Reserved 5 * 6 * This is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU Lesser General Public 8 * License version 2.1, as published by the Free Software 9 * Foundation. See file COPYING. 10 * 11 */ 12 13 #ifdef __KERNEL__ 14 # include <linux/string.h> 15 # include <linux/slab.h> 16 # include <linux/bug.h> 17 # include <linux/kernel.h> 18 # include <linux/crush/crush.h> 19 # include <linux/crush/hash.h> 20 #else 21 # include "crush_compat.h" 22 # include "crush.h" 23 # include "hash.h" 24 #endif 25 #include "crush_ln_table.h" 26 27 #define dprintk(args...) /* printf(args) */ 28 29 /* 30 * Implement the core CRUSH mapping algorithm. 31 */ 32 33 /** 34 * crush_find_rule - find a crush_rule id for a given ruleset, type, and size. 35 * @map: the crush_map 36 * @ruleset: the storage ruleset id (user defined) 37 * @type: storage ruleset type (user defined) 38 * @size: output set size 39 */ 40 int crush_find_rule(const struct crush_map *map, int ruleset, int type, int size) 41 { 42 __u32 i; 43 44 for (i = 0; i < map->max_rules; i++) { 45 if (map->rules[i] && 46 map->rules[i]->mask.ruleset == ruleset && 47 map->rules[i]->mask.type == type && 48 map->rules[i]->mask.min_size <= size && 49 map->rules[i]->mask.max_size >= size) 50 return i; 51 } 52 return -1; 53 } 54 55 56 /* 57 * bucket choose methods 58 * 59 * For each bucket algorithm, we have a "choose" method that, given a 60 * crush input @x and replica position (usually, position in output set) @r, 61 * will produce an item in the bucket. 62 */ 63 64 /* 65 * Choose based on a random permutation of the bucket. 66 * 67 * We used to use some prime number arithmetic to do this, but it 68 * wasn't very random, and had some other bad behaviors. Instead, we 69 * calculate an actual random permutation of the bucket members. 70 * Since this is expensive, we optimize for the r=0 case, which 71 * captures the vast majority of calls. 72 */ 73 static int bucket_perm_choose(struct crush_bucket *bucket, 74 int x, int r) 75 { 76 unsigned int pr = r % bucket->size; 77 unsigned int i, s; 78 79 /* start a new permutation if @x has changed */ 80 if (bucket->perm_x != (__u32)x || bucket->perm_n == 0) { 81 dprintk("bucket %d new x=%d\n", bucket->id, x); 82 bucket->perm_x = x; 83 84 /* optimize common r=0 case */ 85 if (pr == 0) { 86 s = crush_hash32_3(bucket->hash, x, bucket->id, 0) % 87 bucket->size; 88 bucket->perm[0] = s; 89 bucket->perm_n = 0xffff; /* magic value, see below */ 90 goto out; 91 } 92 93 for (i = 0; i < bucket->size; i++) 94 bucket->perm[i] = i; 95 bucket->perm_n = 0; 96 } else if (bucket->perm_n == 0xffff) { 97 /* clean up after the r=0 case above */ 98 for (i = 1; i < bucket->size; i++) 99 bucket->perm[i] = i; 100 bucket->perm[bucket->perm[0]] = 0; 101 bucket->perm_n = 1; 102 } 103 104 /* calculate permutation up to pr */ 105 for (i = 0; i < bucket->perm_n; i++) 106 dprintk(" perm_choose have %d: %d\n", i, bucket->perm[i]); 107 while (bucket->perm_n <= pr) { 108 unsigned int p = bucket->perm_n; 109 /* no point in swapping the final entry */ 110 if (p < bucket->size - 1) { 111 i = crush_hash32_3(bucket->hash, x, bucket->id, p) % 112 (bucket->size - p); 113 if (i) { 114 unsigned int t = bucket->perm[p + i]; 115 bucket->perm[p + i] = bucket->perm[p]; 116 bucket->perm[p] = t; 117 } 118 dprintk(" perm_choose swap %d with %d\n", p, p+i); 119 } 120 bucket->perm_n++; 121 } 122 for (i = 0; i < bucket->size; i++) 123 dprintk(" perm_choose %d: %d\n", i, bucket->perm[i]); 124 125 s = bucket->perm[pr]; 126 out: 127 dprintk(" perm_choose %d sz=%d x=%d r=%d (%d) s=%d\n", bucket->id, 128 bucket->size, x, r, pr, s); 129 return bucket->items[s]; 130 } 131 132 /* uniform */ 133 static int bucket_uniform_choose(struct crush_bucket_uniform *bucket, 134 int x, int r) 135 { 136 return bucket_perm_choose(&bucket->h, x, r); 137 } 138 139 /* list */ 140 static int bucket_list_choose(struct crush_bucket_list *bucket, 141 int x, int r) 142 { 143 int i; 144 145 for (i = bucket->h.size-1; i >= 0; i--) { 146 __u64 w = crush_hash32_4(bucket->h.hash, x, bucket->h.items[i], 147 r, bucket->h.id); 148 w &= 0xffff; 149 dprintk("list_choose i=%d x=%d r=%d item %d weight %x " 150 "sw %x rand %llx", 151 i, x, r, bucket->h.items[i], bucket->item_weights[i], 152 bucket->sum_weights[i], w); 153 w *= bucket->sum_weights[i]; 154 w = w >> 16; 155 /*dprintk(" scaled %llx\n", w);*/ 156 if (w < bucket->item_weights[i]) 157 return bucket->h.items[i]; 158 } 159 160 dprintk("bad list sums for bucket %d\n", bucket->h.id); 161 return bucket->h.items[0]; 162 } 163 164 165 /* (binary) tree */ 166 static int height(int n) 167 { 168 int h = 0; 169 while ((n & 1) == 0) { 170 h++; 171 n = n >> 1; 172 } 173 return h; 174 } 175 176 static int left(int x) 177 { 178 int h = height(x); 179 return x - (1 << (h-1)); 180 } 181 182 static int right(int x) 183 { 184 int h = height(x); 185 return x + (1 << (h-1)); 186 } 187 188 static int terminal(int x) 189 { 190 return x & 1; 191 } 192 193 static int bucket_tree_choose(struct crush_bucket_tree *bucket, 194 int x, int r) 195 { 196 int n; 197 __u32 w; 198 __u64 t; 199 200 /* start at root */ 201 n = bucket->num_nodes >> 1; 202 203 while (!terminal(n)) { 204 int l; 205 /* pick point in [0, w) */ 206 w = bucket->node_weights[n]; 207 t = (__u64)crush_hash32_4(bucket->h.hash, x, n, r, 208 bucket->h.id) * (__u64)w; 209 t = t >> 32; 210 211 /* descend to the left or right? */ 212 l = left(n); 213 if (t < bucket->node_weights[l]) 214 n = l; 215 else 216 n = right(n); 217 } 218 219 return bucket->h.items[n >> 1]; 220 } 221 222 223 /* straw */ 224 225 static int bucket_straw_choose(struct crush_bucket_straw *bucket, 226 int x, int r) 227 { 228 __u32 i; 229 int high = 0; 230 __u64 high_draw = 0; 231 __u64 draw; 232 233 for (i = 0; i < bucket->h.size; i++) { 234 draw = crush_hash32_3(bucket->h.hash, x, bucket->h.items[i], r); 235 draw &= 0xffff; 236 draw *= bucket->straws[i]; 237 if (i == 0 || draw > high_draw) { 238 high = i; 239 high_draw = draw; 240 } 241 } 242 return bucket->h.items[high]; 243 } 244 245 /* compute 2^44*log2(input+1) */ 246 static __u64 crush_ln(unsigned int xin) 247 { 248 unsigned int x = xin, x1; 249 int iexpon, index1, index2; 250 __u64 RH, LH, LL, xl64, result; 251 252 x++; 253 254 /* normalize input */ 255 iexpon = 15; 256 while (!(x & 0x18000)) { 257 x <<= 1; 258 iexpon--; 259 } 260 261 index1 = (x >> 8) << 1; 262 /* RH ~ 2^56/index1 */ 263 RH = __RH_LH_tbl[index1 - 256]; 264 /* LH ~ 2^48 * log2(index1/256) */ 265 LH = __RH_LH_tbl[index1 + 1 - 256]; 266 267 /* RH*x ~ 2^48 * (2^15 + xf), xf<2^8 */ 268 xl64 = (__s64)x * RH; 269 xl64 >>= 48; 270 x1 = xl64; 271 272 result = iexpon; 273 result <<= (12 + 32); 274 275 index2 = x1 & 0xff; 276 /* LL ~ 2^48*log2(1.0+index2/2^15) */ 277 LL = __LL_tbl[index2]; 278 279 LH = LH + LL; 280 281 LH >>= (48 - 12 - 32); 282 result += LH; 283 284 return result; 285 } 286 287 288 /* 289 * straw2 290 * 291 * for reference, see: 292 * 293 * http://en.wikipedia.org/wiki/Exponential_distribution#Distribution_of_the_minimum_of_exponential_random_variables 294 * 295 */ 296 297 static int bucket_straw2_choose(struct crush_bucket_straw2 *bucket, 298 int x, int r) 299 { 300 unsigned int i, high = 0; 301 unsigned int u; 302 unsigned int w; 303 __s64 ln, draw, high_draw = 0; 304 305 for (i = 0; i < bucket->h.size; i++) { 306 w = bucket->item_weights[i]; 307 if (w) { 308 u = crush_hash32_3(bucket->h.hash, x, 309 bucket->h.items[i], r); 310 u &= 0xffff; 311 312 /* 313 * for some reason slightly less than 0x10000 produces 314 * a slightly more accurate distribution... probably a 315 * rounding effect. 316 * 317 * the natural log lookup table maps [0,0xffff] 318 * (corresponding to real numbers [1/0x10000, 1] to 319 * [0, 0xffffffffffff] (corresponding to real numbers 320 * [-11.090355,0]). 321 */ 322 ln = crush_ln(u) - 0x1000000000000ll; 323 324 /* 325 * divide by 16.16 fixed-point weight. note 326 * that the ln value is negative, so a larger 327 * weight means a larger (less negative) value 328 * for draw. 329 */ 330 draw = div64_s64(ln, w); 331 } else { 332 draw = S64_MIN; 333 } 334 335 if (i == 0 || draw > high_draw) { 336 high = i; 337 high_draw = draw; 338 } 339 } 340 return bucket->h.items[high]; 341 } 342 343 344 static int crush_bucket_choose(struct crush_bucket *in, int x, int r) 345 { 346 dprintk(" crush_bucket_choose %d x=%d r=%d\n", in->id, x, r); 347 BUG_ON(in->size == 0); 348 switch (in->alg) { 349 case CRUSH_BUCKET_UNIFORM: 350 return bucket_uniform_choose((struct crush_bucket_uniform *)in, 351 x, r); 352 case CRUSH_BUCKET_LIST: 353 return bucket_list_choose((struct crush_bucket_list *)in, 354 x, r); 355 case CRUSH_BUCKET_TREE: 356 return bucket_tree_choose((struct crush_bucket_tree *)in, 357 x, r); 358 case CRUSH_BUCKET_STRAW: 359 return bucket_straw_choose((struct crush_bucket_straw *)in, 360 x, r); 361 case CRUSH_BUCKET_STRAW2: 362 return bucket_straw2_choose((struct crush_bucket_straw2 *)in, 363 x, r); 364 default: 365 dprintk("unknown bucket %d alg %d\n", in->id, in->alg); 366 return in->items[0]; 367 } 368 } 369 370 371 /* 372 * true if device is marked "out" (failed, fully offloaded) 373 * of the cluster 374 */ 375 static int is_out(const struct crush_map *map, 376 const __u32 *weight, int weight_max, 377 int item, int x) 378 { 379 if (item >= weight_max) 380 return 1; 381 if (weight[item] >= 0x10000) 382 return 0; 383 if (weight[item] == 0) 384 return 1; 385 if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff) 386 < weight[item]) 387 return 0; 388 return 1; 389 } 390 391 /** 392 * crush_choose_firstn - choose numrep distinct items of given type 393 * @map: the crush_map 394 * @bucket: the bucket we are choose an item from 395 * @x: crush input value 396 * @numrep: the number of items to choose 397 * @type: the type of item to choose 398 * @out: pointer to output vector 399 * @outpos: our position in that vector 400 * @out_size: size of the out vector 401 * @tries: number of attempts to make 402 * @recurse_tries: number of attempts to have recursive chooseleaf make 403 * @local_retries: localized retries 404 * @local_fallback_retries: localized fallback retries 405 * @recurse_to_leaf: true if we want one device under each item of given type (chooseleaf instead of choose) 406 * @stable: stable mode starts rep=0 in the recursive call for all replicas 407 * @vary_r: pass r to recursive calls 408 * @out2: second output vector for leaf items (if @recurse_to_leaf) 409 * @parent_r: r value passed from the parent 410 */ 411 static int crush_choose_firstn(const struct crush_map *map, 412 struct crush_bucket *bucket, 413 const __u32 *weight, int weight_max, 414 int x, int numrep, int type, 415 int *out, int outpos, 416 int out_size, 417 unsigned int tries, 418 unsigned int recurse_tries, 419 unsigned int local_retries, 420 unsigned int local_fallback_retries, 421 int recurse_to_leaf, 422 unsigned int vary_r, 423 unsigned int stable, 424 int *out2, 425 int parent_r) 426 { 427 int rep; 428 unsigned int ftotal, flocal; 429 int retry_descent, retry_bucket, skip_rep; 430 struct crush_bucket *in = bucket; 431 int r; 432 int i; 433 int item = 0; 434 int itemtype; 435 int collide, reject; 436 int count = out_size; 437 438 dprintk("CHOOSE%s bucket %d x %d outpos %d numrep %d tries %d recurse_tries %d local_retries %d local_fallback_retries %d parent_r %d stable %d\n", 439 recurse_to_leaf ? "_LEAF" : "", 440 bucket->id, x, outpos, numrep, 441 tries, recurse_tries, local_retries, local_fallback_retries, 442 parent_r, stable); 443 444 for (rep = stable ? 0 : outpos; rep < numrep && count > 0 ; rep++) { 445 /* keep trying until we get a non-out, non-colliding item */ 446 ftotal = 0; 447 skip_rep = 0; 448 do { 449 retry_descent = 0; 450 in = bucket; /* initial bucket */ 451 452 /* choose through intervening buckets */ 453 flocal = 0; 454 do { 455 collide = 0; 456 retry_bucket = 0; 457 r = rep + parent_r; 458 /* r' = r + f_total */ 459 r += ftotal; 460 461 /* bucket choose */ 462 if (in->size == 0) { 463 reject = 1; 464 goto reject; 465 } 466 if (local_fallback_retries > 0 && 467 flocal >= (in->size>>1) && 468 flocal > local_fallback_retries) 469 item = bucket_perm_choose(in, x, r); 470 else 471 item = crush_bucket_choose(in, x, r); 472 if (item >= map->max_devices) { 473 dprintk(" bad item %d\n", item); 474 skip_rep = 1; 475 break; 476 } 477 478 /* desired type? */ 479 if (item < 0) 480 itemtype = map->buckets[-1-item]->type; 481 else 482 itemtype = 0; 483 dprintk(" item %d type %d\n", item, itemtype); 484 485 /* keep going? */ 486 if (itemtype != type) { 487 if (item >= 0 || 488 (-1-item) >= map->max_buckets) { 489 dprintk(" bad item type %d\n", type); 490 skip_rep = 1; 491 break; 492 } 493 in = map->buckets[-1-item]; 494 retry_bucket = 1; 495 continue; 496 } 497 498 /* collision? */ 499 for (i = 0; i < outpos; i++) { 500 if (out[i] == item) { 501 collide = 1; 502 break; 503 } 504 } 505 506 reject = 0; 507 if (!collide && recurse_to_leaf) { 508 if (item < 0) { 509 int sub_r; 510 if (vary_r) 511 sub_r = r >> (vary_r-1); 512 else 513 sub_r = 0; 514 if (crush_choose_firstn(map, 515 map->buckets[-1-item], 516 weight, weight_max, 517 x, stable ? 1 : outpos+1, 0, 518 out2, outpos, count, 519 recurse_tries, 0, 520 local_retries, 521 local_fallback_retries, 522 0, 523 vary_r, 524 stable, 525 NULL, 526 sub_r) <= outpos) 527 /* didn't get leaf */ 528 reject = 1; 529 } else { 530 /* we already have a leaf! */ 531 out2[outpos] = item; 532 } 533 } 534 535 if (!reject) { 536 /* out? */ 537 if (itemtype == 0) 538 reject = is_out(map, weight, 539 weight_max, 540 item, x); 541 else 542 reject = 0; 543 } 544 545 reject: 546 if (reject || collide) { 547 ftotal++; 548 flocal++; 549 550 if (collide && flocal <= local_retries) 551 /* retry locally a few times */ 552 retry_bucket = 1; 553 else if (local_fallback_retries > 0 && 554 flocal <= in->size + local_fallback_retries) 555 /* exhaustive bucket search */ 556 retry_bucket = 1; 557 else if (ftotal < tries) 558 /* then retry descent */ 559 retry_descent = 1; 560 else 561 /* else give up */ 562 skip_rep = 1; 563 dprintk(" reject %d collide %d " 564 "ftotal %u flocal %u\n", 565 reject, collide, ftotal, 566 flocal); 567 } 568 } while (retry_bucket); 569 } while (retry_descent); 570 571 if (skip_rep) { 572 dprintk("skip rep\n"); 573 continue; 574 } 575 576 dprintk("CHOOSE got %d\n", item); 577 out[outpos] = item; 578 outpos++; 579 count--; 580 #ifndef __KERNEL__ 581 if (map->choose_tries && ftotal <= map->choose_total_tries) 582 map->choose_tries[ftotal]++; 583 #endif 584 } 585 586 dprintk("CHOOSE returns %d\n", outpos); 587 return outpos; 588 } 589 590 591 /** 592 * crush_choose_indep: alternative breadth-first positionally stable mapping 593 * 594 */ 595 static void crush_choose_indep(const struct crush_map *map, 596 struct crush_bucket *bucket, 597 const __u32 *weight, int weight_max, 598 int x, int left, int numrep, int type, 599 int *out, int outpos, 600 unsigned int tries, 601 unsigned int recurse_tries, 602 int recurse_to_leaf, 603 int *out2, 604 int parent_r) 605 { 606 struct crush_bucket *in = bucket; 607 int endpos = outpos + left; 608 int rep; 609 unsigned int ftotal; 610 int r; 611 int i; 612 int item = 0; 613 int itemtype; 614 int collide; 615 616 dprintk("CHOOSE%s INDEP bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "", 617 bucket->id, x, outpos, numrep); 618 619 /* initially my result is undefined */ 620 for (rep = outpos; rep < endpos; rep++) { 621 out[rep] = CRUSH_ITEM_UNDEF; 622 if (out2) 623 out2[rep] = CRUSH_ITEM_UNDEF; 624 } 625 626 for (ftotal = 0; left > 0 && ftotal < tries; ftotal++) { 627 #ifdef DEBUG_INDEP 628 if (out2 && ftotal) { 629 dprintk("%u %d a: ", ftotal, left); 630 for (rep = outpos; rep < endpos; rep++) { 631 dprintk(" %d", out[rep]); 632 } 633 dprintk("\n"); 634 dprintk("%u %d b: ", ftotal, left); 635 for (rep = outpos; rep < endpos; rep++) { 636 dprintk(" %d", out2[rep]); 637 } 638 dprintk("\n"); 639 } 640 #endif 641 for (rep = outpos; rep < endpos; rep++) { 642 if (out[rep] != CRUSH_ITEM_UNDEF) 643 continue; 644 645 in = bucket; /* initial bucket */ 646 647 /* choose through intervening buckets */ 648 for (;;) { 649 /* note: we base the choice on the position 650 * even in the nested call. that means that 651 * if the first layer chooses the same bucket 652 * in a different position, we will tend to 653 * choose a different item in that bucket. 654 * this will involve more devices in data 655 * movement and tend to distribute the load. 656 */ 657 r = rep + parent_r; 658 659 /* be careful */ 660 if (in->alg == CRUSH_BUCKET_UNIFORM && 661 in->size % numrep == 0) 662 /* r'=r+(n+1)*f_total */ 663 r += (numrep+1) * ftotal; 664 else 665 /* r' = r + n*f_total */ 666 r += numrep * ftotal; 667 668 /* bucket choose */ 669 if (in->size == 0) { 670 dprintk(" empty bucket\n"); 671 break; 672 } 673 674 item = crush_bucket_choose(in, x, r); 675 if (item >= map->max_devices) { 676 dprintk(" bad item %d\n", item); 677 out[rep] = CRUSH_ITEM_NONE; 678 if (out2) 679 out2[rep] = CRUSH_ITEM_NONE; 680 left--; 681 break; 682 } 683 684 /* desired type? */ 685 if (item < 0) 686 itemtype = map->buckets[-1-item]->type; 687 else 688 itemtype = 0; 689 dprintk(" item %d type %d\n", item, itemtype); 690 691 /* keep going? */ 692 if (itemtype != type) { 693 if (item >= 0 || 694 (-1-item) >= map->max_buckets) { 695 dprintk(" bad item type %d\n", type); 696 out[rep] = CRUSH_ITEM_NONE; 697 if (out2) 698 out2[rep] = 699 CRUSH_ITEM_NONE; 700 left--; 701 break; 702 } 703 in = map->buckets[-1-item]; 704 continue; 705 } 706 707 /* collision? */ 708 collide = 0; 709 for (i = outpos; i < endpos; i++) { 710 if (out[i] == item) { 711 collide = 1; 712 break; 713 } 714 } 715 if (collide) 716 break; 717 718 if (recurse_to_leaf) { 719 if (item < 0) { 720 crush_choose_indep(map, 721 map->buckets[-1-item], 722 weight, weight_max, 723 x, 1, numrep, 0, 724 out2, rep, 725 recurse_tries, 0, 726 0, NULL, r); 727 if (out2[rep] == CRUSH_ITEM_NONE) { 728 /* placed nothing; no leaf */ 729 break; 730 } 731 } else { 732 /* we already have a leaf! */ 733 out2[rep] = item; 734 } 735 } 736 737 /* out? */ 738 if (itemtype == 0 && 739 is_out(map, weight, weight_max, item, x)) 740 break; 741 742 /* yay! */ 743 out[rep] = item; 744 left--; 745 break; 746 } 747 } 748 } 749 for (rep = outpos; rep < endpos; rep++) { 750 if (out[rep] == CRUSH_ITEM_UNDEF) { 751 out[rep] = CRUSH_ITEM_NONE; 752 } 753 if (out2 && out2[rep] == CRUSH_ITEM_UNDEF) { 754 out2[rep] = CRUSH_ITEM_NONE; 755 } 756 } 757 #ifndef __KERNEL__ 758 if (map->choose_tries && ftotal <= map->choose_total_tries) 759 map->choose_tries[ftotal]++; 760 #endif 761 #ifdef DEBUG_INDEP 762 if (out2) { 763 dprintk("%u %d a: ", ftotal, left); 764 for (rep = outpos; rep < endpos; rep++) { 765 dprintk(" %d", out[rep]); 766 } 767 dprintk("\n"); 768 dprintk("%u %d b: ", ftotal, left); 769 for (rep = outpos; rep < endpos; rep++) { 770 dprintk(" %d", out2[rep]); 771 } 772 dprintk("\n"); 773 } 774 #endif 775 } 776 777 /** 778 * crush_do_rule - calculate a mapping with the given input and rule 779 * @map: the crush_map 780 * @ruleno: the rule id 781 * @x: hash input 782 * @result: pointer to result vector 783 * @result_max: maximum result size 784 * @weight: weight vector (for map leaves) 785 * @weight_max: size of weight vector 786 * @scratch: scratch vector for private use; must be >= 3 * result_max 787 */ 788 int crush_do_rule(const struct crush_map *map, 789 int ruleno, int x, int *result, int result_max, 790 const __u32 *weight, int weight_max, 791 int *scratch) 792 { 793 int result_len; 794 int *a = scratch; 795 int *b = scratch + result_max; 796 int *c = scratch + result_max*2; 797 int recurse_to_leaf; 798 int *w; 799 int wsize = 0; 800 int *o; 801 int osize; 802 int *tmp; 803 struct crush_rule *rule; 804 __u32 step; 805 int i, j; 806 int numrep; 807 int out_size; 808 /* 809 * the original choose_total_tries value was off by one (it 810 * counted "retries" and not "tries"). add one. 811 */ 812 int choose_tries = map->choose_total_tries + 1; 813 int choose_leaf_tries = 0; 814 /* 815 * the local tries values were counted as "retries", though, 816 * and need no adjustment 817 */ 818 int choose_local_retries = map->choose_local_tries; 819 int choose_local_fallback_retries = map->choose_local_fallback_tries; 820 821 int vary_r = map->chooseleaf_vary_r; 822 int stable = map->chooseleaf_stable; 823 824 if ((__u32)ruleno >= map->max_rules) { 825 dprintk(" bad ruleno %d\n", ruleno); 826 return 0; 827 } 828 829 rule = map->rules[ruleno]; 830 result_len = 0; 831 w = a; 832 o = b; 833 834 for (step = 0; step < rule->len; step++) { 835 int firstn = 0; 836 struct crush_rule_step *curstep = &rule->steps[step]; 837 838 switch (curstep->op) { 839 case CRUSH_RULE_TAKE: 840 if ((curstep->arg1 >= 0 && 841 curstep->arg1 < map->max_devices) || 842 (-1-curstep->arg1 >= 0 && 843 -1-curstep->arg1 < map->max_buckets && 844 map->buckets[-1-curstep->arg1])) { 845 w[0] = curstep->arg1; 846 wsize = 1; 847 } else { 848 dprintk(" bad take value %d\n", curstep->arg1); 849 } 850 break; 851 852 case CRUSH_RULE_SET_CHOOSE_TRIES: 853 if (curstep->arg1 > 0) 854 choose_tries = curstep->arg1; 855 break; 856 857 case CRUSH_RULE_SET_CHOOSELEAF_TRIES: 858 if (curstep->arg1 > 0) 859 choose_leaf_tries = curstep->arg1; 860 break; 861 862 case CRUSH_RULE_SET_CHOOSE_LOCAL_TRIES: 863 if (curstep->arg1 >= 0) 864 choose_local_retries = curstep->arg1; 865 break; 866 867 case CRUSH_RULE_SET_CHOOSE_LOCAL_FALLBACK_TRIES: 868 if (curstep->arg1 >= 0) 869 choose_local_fallback_retries = curstep->arg1; 870 break; 871 872 case CRUSH_RULE_SET_CHOOSELEAF_VARY_R: 873 if (curstep->arg1 >= 0) 874 vary_r = curstep->arg1; 875 break; 876 877 case CRUSH_RULE_SET_CHOOSELEAF_STABLE: 878 if (curstep->arg1 >= 0) 879 stable = curstep->arg1; 880 break; 881 882 case CRUSH_RULE_CHOOSELEAF_FIRSTN: 883 case CRUSH_RULE_CHOOSE_FIRSTN: 884 firstn = 1; 885 /* fall through */ 886 case CRUSH_RULE_CHOOSELEAF_INDEP: 887 case CRUSH_RULE_CHOOSE_INDEP: 888 if (wsize == 0) 889 break; 890 891 recurse_to_leaf = 892 curstep->op == 893 CRUSH_RULE_CHOOSELEAF_FIRSTN || 894 curstep->op == 895 CRUSH_RULE_CHOOSELEAF_INDEP; 896 897 /* reset output */ 898 osize = 0; 899 900 for (i = 0; i < wsize; i++) { 901 int bno; 902 /* 903 * see CRUSH_N, CRUSH_N_MINUS macros. 904 * basically, numrep <= 0 means relative to 905 * the provided result_max 906 */ 907 numrep = curstep->arg1; 908 if (numrep <= 0) { 909 numrep += result_max; 910 if (numrep <= 0) 911 continue; 912 } 913 j = 0; 914 /* make sure bucket id is valid */ 915 bno = -1 - w[i]; 916 if (bno < 0 || bno >= map->max_buckets) { 917 /* w[i] is probably CRUSH_ITEM_NONE */ 918 dprintk(" bad w[i] %d\n", w[i]); 919 continue; 920 } 921 if (firstn) { 922 int recurse_tries; 923 if (choose_leaf_tries) 924 recurse_tries = 925 choose_leaf_tries; 926 else if (map->chooseleaf_descend_once) 927 recurse_tries = 1; 928 else 929 recurse_tries = choose_tries; 930 osize += crush_choose_firstn( 931 map, 932 map->buckets[bno], 933 weight, weight_max, 934 x, numrep, 935 curstep->arg2, 936 o+osize, j, 937 result_max-osize, 938 choose_tries, 939 recurse_tries, 940 choose_local_retries, 941 choose_local_fallback_retries, 942 recurse_to_leaf, 943 vary_r, 944 stable, 945 c+osize, 946 0); 947 } else { 948 out_size = ((numrep < (result_max-osize)) ? 949 numrep : (result_max-osize)); 950 crush_choose_indep( 951 map, 952 map->buckets[bno], 953 weight, weight_max, 954 x, out_size, numrep, 955 curstep->arg2, 956 o+osize, j, 957 choose_tries, 958 choose_leaf_tries ? 959 choose_leaf_tries : 1, 960 recurse_to_leaf, 961 c+osize, 962 0); 963 osize += out_size; 964 } 965 } 966 967 if (recurse_to_leaf) 968 /* copy final _leaf_ values to output set */ 969 memcpy(o, c, osize*sizeof(*o)); 970 971 /* swap o and w arrays */ 972 tmp = o; 973 o = w; 974 w = tmp; 975 wsize = osize; 976 break; 977 978 979 case CRUSH_RULE_EMIT: 980 for (i = 0; i < wsize && result_len < result_max; i++) { 981 result[result_len] = w[i]; 982 result_len++; 983 } 984 wsize = 0; 985 break; 986 987 default: 988 dprintk(" unknown op %d at step %d\n", 989 curstep->op, step); 990 break; 991 } 992 } 993 return result_len; 994 } 995