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mapper.c
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linux-6.19.14/net/ceph/crush/mapper.c
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# include <linux/crush/mapper.h> 21#else 22# include "crush_compat.h" 23# include "crush.h" 24# include "hash.h" 25# include "mapper.h" 26#endif 27#include "crush_ln_table.h" 28 29#define dprintk(args...) /* printf(args) */ 30 31/* 32 * Implement the core CRUSH mapping algorithm. 33 */ 34 35/** 36 * crush_find_rule - find a crush_rule id for a given ruleset, type, and size. 37 * @map: the crush_map 38 * @ruleset: the storage ruleset id (user defined) 39 * @type: storage ruleset type (user defined) 40 * @size: output set size 41 */ 42int crush_find_rule(const struct crush_map *map, int ruleset, int type, int size) 43{ 44 __u32 i; 45 46 for (i = 0; i < map->max_rules; i++) { 47 if (map->rules[i] && 48 map->rules[i]->mask.ruleset == ruleset && 49 map->rules[i]->mask.type == type && 50 map->rules[i]->mask.min_size <= size && 51 map->rules[i]->mask.max_size >= size) 52 return i; 53 } 54 return -1; 55} 56 57/* 58 * bucket choose methods 59 * 60 * For each bucket algorithm, we have a "choose" method that, given a 61 * crush input @x and replica position (usually, position in output set) @r, 62 * will produce an item in the bucket. 63 */ 64 65/* 66 * Choose based on a random permutation of the bucket. 67 * 68 * We used to use some prime number arithmetic to do this, but it 69 * wasn't very random, and had some other bad behaviors. Instead, we 70 * calculate an actual random permutation of the bucket members. 71 * Since this is expensive, we optimize for the r=0 case, which 72 * captures the vast majority of calls. 73 */ 74static int bucket_perm_choose(const struct crush_bucket *bucket, 75 struct crush_work_bucket *work, 76 int x, int r) 77{ 78 unsigned int pr = r % bucket->size; 79 unsigned int i, s; 80 81 /* start a new permutation if @x has changed */ 82 if (work->perm_x != (__u32)x || work->perm_n == 0) { 83 dprintk("bucket %d new x=%d\n", bucket->id, x); 84 work->perm_x = x; 85 86 /* optimize common r=0 case */ 87 if (pr == 0) { 88 s = crush_hash32_3(bucket->hash, x, bucket->id, 0) % 89 bucket->size; 90 work->perm[0] = s; 91 work->perm_n = 0xffff; /* magic value, see below */ 92 goto out; 93 } 94 95 for (i = 0; i < bucket->size; i++) 96 work->perm[i] = i; 97 work->perm_n = 0; 98 } else if (work->perm_n == 0xffff) { 99 /* clean up after the r=0 case above */ 100 for (i = 1; i < bucket->size; i++) 101 work->perm[i] = i; 102 work->perm[work->perm[0]] = 0; 103 work->perm_n = 1; 104 } 105 106 /* calculate permutation up to pr */ 107 for (i = 0; i < work->perm_n; i++) 108 dprintk(" perm_choose have %d: %d\n", i, work->perm[i]); 109 while (work->perm_n <= pr) { 110 unsigned int p = work->perm_n; 111 /* no point in swapping the final entry */ 112 if (p < bucket->size - 1) { 113 i = crush_hash32_3(bucket->hash, x, bucket->id, p) % 114 (bucket->size - p); 115 if (i) { 116 unsigned int t = work->perm[p + i]; 117 work->perm[p + i] = work->perm[p]; 118 work->perm[p] = t; 119 } 120 dprintk(" perm_choose swap %d with %d\n", p, p+i); 121 } 122 work->perm_n++; 123 } 124 for (i = 0; i < bucket->size; i++) 125 dprintk(" perm_choose %d: %d\n", i, work->perm[i]); 126 127 s = work->perm[pr]; 128out: 129 dprintk(" perm_choose %d sz=%d x=%d r=%d (%d) s=%d\n", bucket->id, 130 bucket->size, x, r, pr, s); 131 return bucket->items[s]; 132} 133 134/* uniform */ 135static int bucket_uniform_choose(const struct crush_bucket_uniform *bucket, 136 struct crush_work_bucket *work, int x, int r) 137{ 138 return bucket_perm_choose(&bucket->h, work, x, r); 139} 140 141/* list */ 142static int bucket_list_choose(const struct crush_bucket_list *bucket, 143 int x, int r) 144{ 145 int i; 146 147 for (i = bucket->h.size-1; i >= 0; i--) { 148 __u64 w = crush_hash32_4(bucket->h.hash, x, bucket->h.items[i], 149 r, bucket->h.id); 150 w &= 0xffff; 151 dprintk("list_choose i=%d x=%d r=%d item %d weight %x " 152 "sw %x rand %llx", 153 i, x, r, bucket->h.items[i], bucket->item_weights[i], 154 bucket->sum_weights[i], w); 155 w *= bucket->sum_weights[i]; 156 w = w >> 16; 157 /*dprintk(" scaled %llx\n", w);*/ 158 if (w < bucket->item_weights[i]) { 159 return bucket->h.items[i]; 160 } 161 } 162 163 dprintk("bad list sums for bucket %d\n", bucket->h.id); 164 return bucket->h.items[0]; 165} 166 167 168/* (binary) tree */ 169static int height(int n) 170{ 171 int h = 0; 172 while ((n & 1) == 0) { 173 h++; 174 n = n >> 1; 175 } 176 return h; 177} 178 179static int left(int x) 180{ 181 int h = height(x); 182 return x - (1 << (h-1)); 183} 184 185static int right(int x) 186{ 187 int h = height(x); 188 return x + (1 << (h-1)); 189} 190 191static int terminal(int x) 192{ 193 return x & 1; 194} 195 196static int bucket_tree_choose(const struct crush_bucket_tree *bucket, 197 int x, int r) 198{ 199 int n; 200 __u32 w; 201 __u64 t; 202 203 /* start at root */ 204 n = bucket->num_nodes >> 1; 205 206 while (!terminal(n)) { 207 int l; 208 /* pick point in [0, w) */ 209 w = bucket->node_weights[n]; 210 t = (__u64)crush_hash32_4(bucket->h.hash, x, n, r, 211 bucket->h.id) * (__u64)w; 212 t = t >> 32; 213 214 /* descend to the left or right? */ 215 l = left(n); 216 if (t < bucket->node_weights[l]) 217 n = l; 218 else 219 n = right(n); 220 } 221 222 return bucket->h.items[n >> 1]; 223} 224 225 226/* straw */ 227 228static int bucket_straw_choose(const struct crush_bucket_straw *bucket, 229 int x, int r) 230{ 231 __u32 i; 232 int high = 0; 233 __u64 high_draw = 0; 234 __u64 draw; 235 236 for (i = 0; i < bucket->h.size; i++) { 237 draw = crush_hash32_3(bucket->h.hash, x, bucket->h.items[i], r); 238 draw &= 0xffff; 239 draw *= bucket->straws[i]; 240 if (i == 0 || draw > high_draw) { 241 high = i; 242 high_draw = draw; 243 } 244 } 245 return bucket->h.items[high]; 246} 247 248/* compute 2^44*log2(input+1) */ 249static __u64 crush_ln(unsigned int xin) 250{ 251 unsigned int x = xin; 252 int iexpon, index1, index2; 253 __u64 RH, LH, LL, xl64, result; 254 255 x++; 256 257 /* normalize input */ 258 iexpon = 15; 259 260 /* 261 * figure out number of bits we need to shift and 262 * do it in one step instead of iteratively 263 */ 264 if (!(x & 0x18000)) { 265 int bits = __builtin_clz(x & 0x1FFFF) - 16; 266 x <<= bits; 267 iexpon = 15 - bits; 268 } 269 270 index1 = (x >> 8) << 1; 271 /* RH ~ 2^56/index1 */ 272 RH = __RH_LH_tbl[index1 - 256]; 273 /* LH ~ 2^48 * log2(index1/256) */ 274 LH = __RH_LH_tbl[index1 + 1 - 256]; 275 276 /* RH*x ~ 2^48 * (2^15 + xf), xf<2^8 */ 277 xl64 = (__s64)x * RH; 278 xl64 >>= 48; 279 280 result = iexpon; 281 result <<= (12 + 32); 282 283 index2 = xl64 & 0xff; 284 /* LL ~ 2^48*log2(1.0+index2/2^15) */ 285 LL = __LL_tbl[index2]; 286 287 LH = LH + LL; 288 289 LH >>= (48 - 12 - 32); 290 result += LH; 291 292 return result; 293} 294 295 296/* 297 * straw2 298 * 299 * for reference, see: 300 * 301 * https://en.wikipedia.org/wiki/Exponential_distribution#Distribution_of_the_minimum_of_exponential_random_variables 302 * 303 */ 304 305static __u32 *get_choose_arg_weights(const struct crush_bucket_straw2 *bucket, 306 const struct crush_choose_arg *arg, 307 int position) 308{ 309 if (!arg || !arg->weight_set) 310 return bucket->item_weights; 311 312 if (position >= arg->weight_set_size) 313 position = arg->weight_set_size - 1; 314 return arg->weight_set[position].weights; 315} 316 317static __s32 *get_choose_arg_ids(const struct crush_bucket_straw2 *bucket, 318 const struct crush_choose_arg *arg) 319{ 320 if (!arg || !arg->ids) 321 return bucket->h.items; 322 323 return arg->ids; 324} 325 326static int bucket_straw2_choose(const struct crush_bucket_straw2 *bucket, 327 int x, int r, 328 const struct crush_choose_arg *arg, 329 int position) 330{ 331 unsigned int i, high = 0; 332 unsigned int u; 333 __s64 ln, draw, high_draw = 0; 334 __u32 *weights = get_choose_arg_weights(bucket, arg, position); 335 __s32 *ids = get_choose_arg_ids(bucket, arg); 336 337 for (i = 0; i < bucket->h.size; i++) { 338 dprintk("weight 0x%x item %d\n", weights[i], ids[i]); 339 if (weights[i]) { 340 u = crush_hash32_3(bucket->h.hash, x, ids[i], r); 341 u &= 0xffff; 342 343 /* 344 * for some reason slightly less than 0x10000 produces 345 * a slightly more accurate distribution... probably a 346 * rounding effect. 347 * 348 * the natural log lookup table maps [0,0xffff] 349 * (corresponding to real numbers [1/0x10000, 1] to 350 * [0, 0xffffffffffff] (corresponding to real numbers 351 * [-11.090355,0]). 352 */ 353 ln = crush_ln(u) - 0x1000000000000ll; 354 355 /* 356 * divide by 16.16 fixed-point weight. note 357 * that the ln value is negative, so a larger 358 * weight means a larger (less negative) value 359 * for draw. 360 */ 361 draw = div64_s64(ln, weights[i]); 362 } else { 363 draw = S64_MIN; 364 } 365 366 if (i == 0 || draw > high_draw) { 367 high = i; 368 high_draw = draw; 369 } 370 } 371 372 return bucket->h.items[high]; 373} 374 375 376static int crush_bucket_choose(const struct crush_bucket *in, 377 struct crush_work_bucket *work, 378 int x, int r, 379 const struct crush_choose_arg *arg, 380 int position) 381{ 382 dprintk(" crush_bucket_choose %d x=%d r=%d\n", in->id, x, r); 383 BUG_ON(in->size == 0); 384 switch (in->alg) { 385 case CRUSH_BUCKET_UNIFORM: 386 return bucket_uniform_choose( 387 (const struct crush_bucket_uniform *)in, 388 work, x, r); 389 case CRUSH_BUCKET_LIST: 390 return bucket_list_choose((const struct crush_bucket_list *)in, 391 x, r); 392 case CRUSH_BUCKET_TREE: 393 return bucket_tree_choose((const struct crush_bucket_tree *)in, 394 x, r); 395 case CRUSH_BUCKET_STRAW: 396 return bucket_straw_choose( 397 (const struct crush_bucket_straw *)in, 398 x, r); 399 case CRUSH_BUCKET_STRAW2: 400 return bucket_straw2_choose( 401 (const struct crush_bucket_straw2 *)in, 402 x, r, arg, position); 403 default: 404 dprintk("unknown bucket %d alg %d\n", in->id, in->alg); 405 return in->items[0]; 406 } 407} 408 409/* 410 * true if device is marked "out" (failed, fully offloaded) 411 * of the cluster 412 */ 413static int is_out(const struct crush_map *map, 414 const __u32 *weight, int weight_max, 415 int item, int x) 416{ 417 if (item >= weight_max) 418 return 1; 419 if (weight[item] >= 0x10000) 420 return 0; 421 if (weight[item] == 0) 422 return 1; 423 if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff) 424 < weight[item]) 425 return 0; 426 return 1; 427} 428 429/** 430 * crush_choose_firstn - choose numrep distinct items of given type 431 * @map: the crush_map 432 * @work: working space initialized by crush_init_workspace() 433 * @bucket: the bucket we are choose an item from 434 * @weight: weight vector (for map leaves) 435 * @weight_max: size of weight vector 436 * @x: crush input value 437 * @numrep: the number of items to choose 438 * @type: the type of item to choose 439 * @out: pointer to output vector 440 * @outpos: our position in that vector 441 * @out_size: size of the out vector 442 * @tries: number of attempts to make 443 * @recurse_tries: number of attempts to have recursive chooseleaf make 444 * @local_retries: localized retries 445 * @local_fallback_retries: localized fallback retries 446 * @recurse_to_leaf: true if we want one device under each item of given type (chooseleaf instead of choose) 447 * @stable: stable mode starts rep=0 in the recursive call for all replicas 448 * @vary_r: pass r to recursive calls 449 * @out2: second output vector for leaf items (if @recurse_to_leaf) 450 * @parent_r: r value passed from the parent 451 * @choose_args: weights and ids for each known bucket 452 */ 453static int crush_choose_firstn(const struct crush_map *map, 454 struct crush_work *work, 455 const struct crush_bucket *bucket, 456 const __u32 *weight, int weight_max, 457 int x, int numrep, int type, 458 int *out, int outpos, 459 int out_size, 460 unsigned int tries, 461 unsigned int recurse_tries, 462 unsigned int local_retries, 463 unsigned int local_fallback_retries, 464 int recurse_to_leaf, 465 unsigned int vary_r, 466 unsigned int stable, 467 int *out2, 468 int parent_r, 469 const struct crush_choose_arg *choose_args) 470{ 471 int rep; 472 unsigned int ftotal, flocal; 473 int retry_descent, retry_bucket, skip_rep; 474 const struct crush_bucket *in = bucket; 475 int r; 476 int i; 477 int item = 0; 478 int itemtype; 479 int collide, reject; 480 int count = out_size; 481 482 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", 483 recurse_to_leaf ? "_LEAF" : "", 484 bucket->id, x, outpos, numrep, 485 tries, recurse_tries, local_retries, local_fallback_retries, 486 parent_r, stable); 487 488 for (rep = stable ? 0 : outpos; rep < numrep && count > 0 ; rep++) { 489 /* keep trying until we get a non-out, non-colliding item */ 490 ftotal = 0; 491 skip_rep = 0; 492 do { 493 retry_descent = 0; 494 in = bucket; /* initial bucket */ 495 496 /* choose through intervening buckets */ 497 flocal = 0; 498 do { 499 collide = 0; 500 retry_bucket = 0; 501 r = rep + parent_r; 502 /* r' = r + f_total */ 503 r += ftotal; 504 505 /* bucket choose */ 506 if (in->size == 0) { 507 reject = 1; 508 goto reject; 509 } 510 if (local_fallback_retries > 0 && 511 flocal >= (in->size>>1) && 512 flocal > local_fallback_retries) 513 item = bucket_perm_choose( 514 in, work->work[-1-in->id], 515 x, r); 516 else 517 item = crush_bucket_choose( 518 in, work->work[-1-in->id], 519 x, r, 520 (choose_args ? 521 &choose_args[-1-in->id] : NULL), 522 outpos); 523 if (item >= map->max_devices) { 524 dprintk(" bad item %d\n", item); 525 skip_rep = 1; 526 break; 527 } 528 529 /* desired type? */ 530 if (item < 0) 531 itemtype = map->buckets[-1-item]->type; 532 else 533 itemtype = 0; 534 dprintk(" item %d type %d\n", item, itemtype); 535 536 /* keep going? */ 537 if (itemtype != type) { 538 if (item >= 0 || 539 (-1-item) >= map->max_buckets) { 540 dprintk(" bad item type %d\n", type); 541 skip_rep = 1; 542 break; 543 } 544 in = map->buckets[-1-item]; 545 retry_bucket = 1; 546 continue; 547 } 548 549 /* collision? */ 550 for (i = 0; i < outpos; i++) { 551 if (out[i] == item) { 552 collide = 1; 553 break; 554 } 555 } 556 557 reject = 0; 558 if (!collide && recurse_to_leaf) { 559 if (item < 0) { 560 int sub_r; 561 if (vary_r) 562 sub_r = r >> (vary_r-1); 563 else 564 sub_r = 0; 565 if (crush_choose_firstn( 566 map, 567 work, 568 map->buckets[-1-item], 569 weight, weight_max, 570 x, stable ? 1 : outpos+1, 0, 571 out2, outpos, count, 572 recurse_tries, 0, 573 local_retries, 574 local_fallback_retries, 575 0, 576 vary_r, 577 stable, 578 NULL, 579 sub_r, 580 choose_args) <= outpos) 581 /* didn't get leaf */ 582 reject = 1; 583 } else { 584 /* we already have a leaf! */ 585 out2[outpos] = item; 586 } 587 } 588 589 if (!reject && !collide) { 590 /* out? */ 591 if (itemtype == 0) 592 reject = is_out(map, weight, 593 weight_max, 594 item, x); 595 } 596 597reject: 598 if (reject || collide) { 599 ftotal++; 600 flocal++; 601 602 if (collide && flocal <= local_retries) 603 /* retry locally a few times */ 604 retry_bucket = 1; 605 else if (local_fallback_retries > 0 && 606 flocal <= in->size + local_fallback_retries) 607 /* exhaustive bucket search */ 608 retry_bucket = 1; 609 else if (ftotal < tries) 610 /* then retry descent */ 611 retry_descent = 1; 612 else 613 /* else give up */ 614 skip_rep = 1; 615 dprintk(" reject %d collide %d " 616 "ftotal %u flocal %u\n", 617 reject, collide, ftotal, 618 flocal); 619 } 620 } while (retry_bucket); 621 } while (retry_descent); 622 623 if (skip_rep) { 624 dprintk("skip rep\n"); 625 continue; 626 } 627 628 dprintk("CHOOSE got %d\n", item); 629 out[outpos] = item; 630 outpos++; 631 count--; 632#ifndef __KERNEL__ 633 if (map->choose_tries && ftotal <= map->choose_total_tries) 634 map->choose_tries[ftotal]++; 635#endif 636 } 637 638 dprintk("CHOOSE returns %d\n", outpos); 639 return outpos; 640} 641 642 643/* 644 * crush_choose_indep: alternative breadth-first positionally stable mapping 645 */ 646static void crush_choose_indep(const struct crush_map *map, 647 struct crush_work *work, 648 const struct crush_bucket *bucket, 649 const __u32 *weight, int weight_max, 650 int x, int left, int numrep, int type, 651 int *out, int outpos, 652 unsigned int tries, 653 unsigned int recurse_tries, 654 int recurse_to_leaf, 655 int *out2, 656 int parent_r, 657 const struct crush_choose_arg *choose_args) 658{ 659 const struct crush_bucket *in = bucket; 660 int endpos = outpos + left; 661 int rep; 662 unsigned int ftotal; 663 int r; 664 int i; 665 int item = 0; 666 int itemtype; 667 int collide; 668 669 dprintk("CHOOSE%s INDEP bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "", 670 bucket->id, x, outpos, numrep); 671 672 /* initially my result is undefined */ 673 for (rep = outpos; rep < endpos; rep++) { 674 out[rep] = CRUSH_ITEM_UNDEF; 675 if (out2) 676 out2[rep] = CRUSH_ITEM_UNDEF; 677 } 678 679 for (ftotal = 0; left > 0 && ftotal < tries; ftotal++) { 680#ifdef DEBUG_INDEP 681 if (out2 && ftotal) { 682 dprintk("%u %d a: ", ftotal, left); 683 for (rep = outpos; rep < endpos; rep++) { 684 dprintk(" %d", out[rep]); 685 } 686 dprintk("\n"); 687 dprintk("%u %d b: ", ftotal, left); 688 for (rep = outpos; rep < endpos; rep++) { 689 dprintk(" %d", out2[rep]); 690 } 691 dprintk("\n"); 692 } 693#endif 694 for (rep = outpos; rep < endpos; rep++) { 695 if (out[rep] != CRUSH_ITEM_UNDEF) 696 continue; 697 698 in = bucket; /* initial bucket */ 699 700 /* choose through intervening buckets */ 701 for (;;) { 702 /* note: we base the choice on the position 703 * even in the nested call. that means that 704 * if the first layer chooses the same bucket 705 * in a different position, we will tend to 706 * choose a different item in that bucket. 707 * this will involve more devices in data 708 * movement and tend to distribute the load. 709 */ 710 r = rep + parent_r; 711 712 /* be careful */ 713 if (in->alg == CRUSH_BUCKET_UNIFORM && 714 in->size % numrep == 0) 715 /* r'=r+(n+1)*f_total */ 716 r += (numrep+1) * ftotal; 717 else 718 /* r' = r + n*f_total */ 719 r += numrep * ftotal; 720 721 /* bucket choose */ 722 if (in->size == 0) { 723 dprintk(" empty bucket\n"); 724 break; 725 } 726 727 item = crush_bucket_choose( 728 in, work->work[-1-in->id], 729 x, r, 730 (choose_args ? 731 &choose_args[-1-in->id] : NULL), 732 outpos); 733 if (item >= map->max_devices) { 734 dprintk(" bad item %d\n", item); 735 out[rep] = CRUSH_ITEM_NONE; 736 if (out2) 737 out2[rep] = CRUSH_ITEM_NONE; 738 left--; 739 break; 740 } 741 742 /* desired type? */ 743 if (item < 0) 744 itemtype = map->buckets[-1-item]->type; 745 else 746 itemtype = 0; 747 dprintk(" item %d type %d\n", item, itemtype); 748 749 /* keep going? */ 750 if (itemtype != type) { 751 if (item >= 0 || 752 (-1-item) >= map->max_buckets) { 753 dprintk(" bad item type %d\n", type); 754 out[rep] = CRUSH_ITEM_NONE; 755 if (out2) 756 out2[rep] = 757 CRUSH_ITEM_NONE; 758 left--; 759 break; 760 } 761 in = map->buckets[-1-item]; 762 continue; 763 } 764 765 /* collision? */ 766 collide = 0; 767 for (i = outpos; i < endpos; i++) { 768 if (out[i] == item) { 769 collide = 1; 770 break; 771 } 772 } 773 if (collide) 774 break; 775 776 if (recurse_to_leaf) { 777 if (item < 0) { 778 crush_choose_indep( 779 map, 780 work, 781 map->buckets[-1-item], 782 weight, weight_max, 783 x, 1, numrep, 0, 784 out2, rep, 785 recurse_tries, 0, 786 0, NULL, r, 787 choose_args); 788 if (out2[rep] == CRUSH_ITEM_NONE) { 789 /* placed nothing; no leaf */ 790 break; 791 } 792 } else { 793 /* we already have a leaf! */ 794 out2[rep] = item; 795 } 796 } 797 798 /* out? */ 799 if (itemtype == 0 && 800 is_out(map, weight, weight_max, item, x)) 801 break; 802 803 /* yay! */ 804 out[rep] = item; 805 left--; 806 break; 807 } 808 } 809 } 810 for (rep = outpos; rep < endpos; rep++) { 811 if (out[rep] == CRUSH_ITEM_UNDEF) { 812 out[rep] = CRUSH_ITEM_NONE; 813 } 814 if (out2 && out2[rep] == CRUSH_ITEM_UNDEF) { 815 out2[rep] = CRUSH_ITEM_NONE; 816 } 817 } 818#ifndef __KERNEL__ 819 if (map->choose_tries && ftotal <= map->choose_total_tries) 820 map->choose_tries[ftotal]++; 821#endif 822#ifdef DEBUG_INDEP 823 if (out2) { 824 dprintk("%u %d a: ", ftotal, left); 825 for (rep = outpos; rep < endpos; rep++) { 826 dprintk(" %d", out[rep]); 827 } 828 dprintk("\n"); 829 dprintk("%u %d b: ", ftotal, left); 830 for (rep = outpos; rep < endpos; rep++) { 831 dprintk(" %d", out2[rep]); 832 } 833 dprintk("\n"); 834 } 835#endif 836} 837 838 839/* 840 * This takes a chunk of memory and sets it up to be a shiny new 841 * working area for a CRUSH placement computation. It must be called 842 * on any newly allocated memory before passing it in to 843 * crush_do_rule. It may be used repeatedly after that, so long as the 844 * map has not changed. If the map /has/ changed, you must make sure 845 * the working size is no smaller than what was allocated and re-run 846 * crush_init_workspace. 847 * 848 * If you do retain the working space between calls to crush, make it 849 * thread-local. 850 */ 851void crush_init_workspace(const struct crush_map *map, void *v) 852{ 853 struct crush_work *w = v; 854 __s32 b; 855 856 /* 857 * We work by moving through the available space and setting 858 * values and pointers as we go. 859 * 860 * It's a bit like Forth's use of the 'allot' word since we 861 * set the pointer first and then reserve the space for it to 862 * point to by incrementing the point. 863 */ 864 v += sizeof(struct crush_work); 865 w->work = v; 866 v += map->max_buckets * sizeof(struct crush_work_bucket *); 867 for (b = 0; b < map->max_buckets; ++b) { 868 if (!map->buckets[b]) 869 continue; 870 871 w->work[b] = v; 872 switch (map->buckets[b]->alg) { 873 default: 874 v += sizeof(struct crush_work_bucket); 875 break; 876 } 877 w->work[b]->perm_x = 0; 878 w->work[b]->perm_n = 0; 879 w->work[b]->perm = v; 880 v += map->buckets[b]->size * sizeof(__u32); 881 } 882 BUG_ON(v - (void *)w != map->working_size); 883} 884 885/** 886 * crush_do_rule - calculate a mapping with the given input and rule 887 * @map: the crush_map 888 * @ruleno: the rule id 889 * @x: hash input 890 * @result: pointer to result vector 891 * @result_max: maximum result size 892 * @weight: weight vector (for map leaves) 893 * @weight_max: size of weight vector 894 * @cwin: pointer to at least crush_work_size() bytes of memory 895 * @choose_args: weights and ids for each known bucket 896 */ 897int crush_do_rule(const struct crush_map *map, 898 int ruleno, int x, int *result, int result_max, 899 const __u32 *weight, int weight_max, 900 void *cwin, const struct crush_choose_arg *choose_args) 901{ 902 int result_len; 903 struct crush_work *cw = cwin; 904 int *a = cwin + map->working_size; 905 int *b = a + result_max; 906 int *c = b + result_max; 907 int *w = a; 908 int *o = b; 909 int recurse_to_leaf; 910 int wsize = 0; 911 int osize; 912 const struct crush_rule *rule; 913 __u32 step; 914 int i, j; 915 int numrep; 916 int out_size; 917 /* 918 * the original choose_total_tries value was off by one (it 919 * counted "retries" and not "tries"). add one. 920 */ 921 int choose_tries = map->choose_total_tries + 1; 922 int choose_leaf_tries = 0; 923 /* 924 * the local tries values were counted as "retries", though, 925 * and need no adjustment 926 */ 927 int choose_local_retries = map->choose_local_tries; 928 int choose_local_fallback_retries = map->choose_local_fallback_tries; 929 930 int vary_r = map->chooseleaf_vary_r; 931 int stable = map->chooseleaf_stable; 932 933 if ((__u32)ruleno >= map->max_rules) { 934 dprintk(" bad ruleno %d\n", ruleno); 935 return 0; 936 } 937 938 rule = map->rules[ruleno]; 939 result_len = 0; 940 941 for (step = 0; step < rule->len; step++) { 942 int firstn = 0; 943 const struct crush_rule_step *curstep = &rule->steps[step]; 944 945 switch (curstep->op) { 946 case CRUSH_RULE_TAKE: 947 if ((curstep->arg1 >= 0 && 948 curstep->arg1 < map->max_devices) || 949 (-1-curstep->arg1 >= 0 && 950 -1-curstep->arg1 < map->max_buckets && 951 map->buckets[-1-curstep->arg1])) { 952 w[0] = curstep->arg1; 953 wsize = 1; 954 } else { 955 dprintk(" bad take value %d\n", curstep->arg1); 956 } 957 break; 958 959 case CRUSH_RULE_SET_CHOOSE_TRIES: 960 if (curstep->arg1 > 0) 961 choose_tries = curstep->arg1; 962 break; 963 964 case CRUSH_RULE_SET_CHOOSELEAF_TRIES: 965 if (curstep->arg1 > 0) 966 choose_leaf_tries = curstep->arg1; 967 break; 968 969 case CRUSH_RULE_SET_CHOOSE_LOCAL_TRIES: 970 if (curstep->arg1 >= 0) 971 choose_local_retries = curstep->arg1; 972 break; 973 974 case CRUSH_RULE_SET_CHOOSE_LOCAL_FALLBACK_TRIES: 975 if (curstep->arg1 >= 0) 976 choose_local_fallback_retries = curstep->arg1; 977 break; 978 979 case CRUSH_RULE_SET_CHOOSELEAF_VARY_R: 980 if (curstep->arg1 >= 0) 981 vary_r = curstep->arg1; 982 break; 983 984 case CRUSH_RULE_SET_CHOOSELEAF_STABLE: 985 if (curstep->arg1 >= 0) 986 stable = curstep->arg1; 987 break; 988 989 case CRUSH_RULE_CHOOSELEAF_FIRSTN: 990 case CRUSH_RULE_CHOOSE_FIRSTN: 991 firstn = 1; 992 fallthrough; 993 case CRUSH_RULE_CHOOSELEAF_INDEP: 994 case CRUSH_RULE_CHOOSE_INDEP: 995 if (wsize == 0) 996 break; 997 998 recurse_to_leaf = 999 curstep->op == 1000 CRUSH_RULE_CHOOSELEAF_FIRSTN || 1001 curstep->op == 1002 CRUSH_RULE_CHOOSELEAF_INDEP; 1003 1004 /* reset output */ 1005 osize = 0; 1006 1007 for (i = 0; i < wsize; i++) { 1008 int bno; 1009 numrep = curstep->arg1; 1010 if (numrep <= 0) { 1011 numrep += result_max; 1012 if (numrep <= 0) 1013 continue; 1014 } 1015 j = 0; 1016 /* make sure bucket id is valid */ 1017 bno = -1 - w[i]; 1018 if (bno < 0 || bno >= map->max_buckets) { 1019 /* w[i] is probably CRUSH_ITEM_NONE */ 1020 dprintk(" bad w[i] %d\n", w[i]); 1021 continue; 1022 } 1023 if (firstn) { 1024 int recurse_tries; 1025 if (choose_leaf_tries) 1026 recurse_tries = 1027 choose_leaf_tries; 1028 else if (map->chooseleaf_descend_once) 1029 recurse_tries = 1; 1030 else 1031 recurse_tries = choose_tries; 1032 osize += crush_choose_firstn( 1033 map, 1034 cw, 1035 map->buckets[bno], 1036 weight, weight_max, 1037 x, numrep, 1038 curstep->arg2, 1039 o+osize, j, 1040 result_max-osize, 1041 choose_tries, 1042 recurse_tries, 1043 choose_local_retries, 1044 choose_local_fallback_retries, 1045 recurse_to_leaf, 1046 vary_r, 1047 stable, 1048 c+osize, 1049 0, 1050 choose_args); 1051 } else { 1052 out_size = ((numrep < (result_max-osize)) ? 1053 numrep : (result_max-osize)); 1054 crush_choose_indep( 1055 map, 1056 cw, 1057 map->buckets[bno], 1058 weight, weight_max, 1059 x, out_size, numrep, 1060 curstep->arg2, 1061 o+osize, j, 1062 choose_tries, 1063 choose_leaf_tries ? 1064 choose_leaf_tries : 1, 1065 recurse_to_leaf, 1066 c+osize, 1067 0, 1068 choose_args); 1069 osize += out_size; 1070 } 1071 } 1072 1073 if (recurse_to_leaf) 1074 /* copy final _leaf_ values to output set */ 1075 memcpy(o, c, osize*sizeof(*o)); 1076 1077 /* swap o and w arrays */ 1078 swap(o, w); 1079 wsize = osize; 1080 break; 1081 1082 1083 case CRUSH_RULE_EMIT: 1084 for (i = 0; i < wsize && result_len < result_max; i++) { 1085 result[result_len] = w[i]; 1086 result_len++; 1087 } 1088 wsize = 0; 1089 break; 1090 1091 default: 1092 dprintk(" unknown op %d at step %d\n", 1093 curstep->op, step); 1094 break; 1095 } 1096 } 1097 1098 return result_len; 1099}
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