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 * @vary_r: pass r to recursive calls 407 * @out2: second output vector for leaf items (if @recurse_to_leaf) 408 * @parent_r: r value passed from the parent 409 */ 410 static int crush_choose_firstn(const struct crush_map *map, 411 struct crush_bucket *bucket, 412 const __u32 *weight, int weight_max, 413 int x, int numrep, int type, 414 int *out, int outpos, 415 int out_size, 416 unsigned int tries, 417 unsigned int recurse_tries, 418 unsigned int local_retries, 419 unsigned int local_fallback_retries, 420 int recurse_to_leaf, 421 unsigned int vary_r, 422 int *out2, 423 int parent_r) 424 { 425 int rep; 426 unsigned int ftotal, flocal; 427 int retry_descent, retry_bucket, skip_rep; 428 struct crush_bucket *in = bucket; 429 int r; 430 int i; 431 int item = 0; 432 int itemtype; 433 int collide, reject; 434 int count = out_size; 435 436 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\n", 437 recurse_to_leaf ? "_LEAF" : "", 438 bucket->id, x, outpos, numrep, 439 tries, recurse_tries, local_retries, local_fallback_retries, 440 parent_r); 441 442 for (rep = outpos; rep < numrep && count > 0 ; rep++) { 443 /* keep trying until we get a non-out, non-colliding item */ 444 ftotal = 0; 445 skip_rep = 0; 446 do { 447 retry_descent = 0; 448 in = bucket; /* initial bucket */ 449 450 /* choose through intervening buckets */ 451 flocal = 0; 452 do { 453 collide = 0; 454 retry_bucket = 0; 455 r = rep + parent_r; 456 /* r' = r + f_total */ 457 r += ftotal; 458 459 /* bucket choose */ 460 if (in->size == 0) { 461 reject = 1; 462 goto reject; 463 } 464 if (local_fallback_retries > 0 && 465 flocal >= (in->size>>1) && 466 flocal > local_fallback_retries) 467 item = bucket_perm_choose(in, x, r); 468 else 469 item = crush_bucket_choose(in, x, r); 470 if (item >= map->max_devices) { 471 dprintk(" bad item %d\n", item); 472 skip_rep = 1; 473 break; 474 } 475 476 /* desired type? */ 477 if (item < 0) 478 itemtype = map->buckets[-1-item]->type; 479 else 480 itemtype = 0; 481 dprintk(" item %d type %d\n", item, itemtype); 482 483 /* keep going? */ 484 if (itemtype != type) { 485 if (item >= 0 || 486 (-1-item) >= map->max_buckets) { 487 dprintk(" bad item type %d\n", type); 488 skip_rep = 1; 489 break; 490 } 491 in = map->buckets[-1-item]; 492 retry_bucket = 1; 493 continue; 494 } 495 496 /* collision? */ 497 for (i = 0; i < outpos; i++) { 498 if (out[i] == item) { 499 collide = 1; 500 break; 501 } 502 } 503 504 reject = 0; 505 if (!collide && recurse_to_leaf) { 506 if (item < 0) { 507 int sub_r; 508 if (vary_r) 509 sub_r = r >> (vary_r-1); 510 else 511 sub_r = 0; 512 if (crush_choose_firstn(map, 513 map->buckets[-1-item], 514 weight, weight_max, 515 x, outpos+1, 0, 516 out2, outpos, count, 517 recurse_tries, 0, 518 local_retries, 519 local_fallback_retries, 520 0, 521 vary_r, 522 NULL, 523 sub_r) <= outpos) 524 /* didn't get leaf */ 525 reject = 1; 526 } else { 527 /* we already have a leaf! */ 528 out2[outpos] = item; 529 } 530 } 531 532 if (!reject) { 533 /* out? */ 534 if (itemtype == 0) 535 reject = is_out(map, weight, 536 weight_max, 537 item, x); 538 else 539 reject = 0; 540 } 541 542 reject: 543 if (reject || collide) { 544 ftotal++; 545 flocal++; 546 547 if (collide && flocal <= local_retries) 548 /* retry locally a few times */ 549 retry_bucket = 1; 550 else if (local_fallback_retries > 0 && 551 flocal <= in->size + local_fallback_retries) 552 /* exhaustive bucket search */ 553 retry_bucket = 1; 554 else if (ftotal < tries) 555 /* then retry descent */ 556 retry_descent = 1; 557 else 558 /* else give up */ 559 skip_rep = 1; 560 dprintk(" reject %d collide %d " 561 "ftotal %u flocal %u\n", 562 reject, collide, ftotal, 563 flocal); 564 } 565 } while (retry_bucket); 566 } while (retry_descent); 567 568 if (skip_rep) { 569 dprintk("skip rep\n"); 570 continue; 571 } 572 573 dprintk("CHOOSE got %d\n", item); 574 out[outpos] = item; 575 outpos++; 576 count--; 577 #ifndef __KERNEL__ 578 if (map->choose_tries && ftotal <= map->choose_total_tries) 579 map->choose_tries[ftotal]++; 580 #endif 581 } 582 583 dprintk("CHOOSE returns %d\n", outpos); 584 return outpos; 585 } 586 587 588 /** 589 * crush_choose_indep: alternative breadth-first positionally stable mapping 590 * 591 */ 592 static void crush_choose_indep(const struct crush_map *map, 593 struct crush_bucket *bucket, 594 const __u32 *weight, int weight_max, 595 int x, int left, int numrep, int type, 596 int *out, int outpos, 597 unsigned int tries, 598 unsigned int recurse_tries, 599 int recurse_to_leaf, 600 int *out2, 601 int parent_r) 602 { 603 struct crush_bucket *in = bucket; 604 int endpos = outpos + left; 605 int rep; 606 unsigned int ftotal; 607 int r; 608 int i; 609 int item = 0; 610 int itemtype; 611 int collide; 612 613 dprintk("CHOOSE%s INDEP bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "", 614 bucket->id, x, outpos, numrep); 615 616 /* initially my result is undefined */ 617 for (rep = outpos; rep < endpos; rep++) { 618 out[rep] = CRUSH_ITEM_UNDEF; 619 if (out2) 620 out2[rep] = CRUSH_ITEM_UNDEF; 621 } 622 623 for (ftotal = 0; left > 0 && ftotal < tries; ftotal++) { 624 #ifdef DEBUG_INDEP 625 if (out2 && ftotal) { 626 dprintk("%u %d a: ", ftotal, left); 627 for (rep = outpos; rep < endpos; rep++) { 628 dprintk(" %d", out[rep]); 629 } 630 dprintk("\n"); 631 dprintk("%u %d b: ", ftotal, left); 632 for (rep = outpos; rep < endpos; rep++) { 633 dprintk(" %d", out2[rep]); 634 } 635 dprintk("\n"); 636 } 637 #endif 638 for (rep = outpos; rep < endpos; rep++) { 639 if (out[rep] != CRUSH_ITEM_UNDEF) 640 continue; 641 642 in = bucket; /* initial bucket */ 643 644 /* choose through intervening buckets */ 645 for (;;) { 646 /* note: we base the choice on the position 647 * even in the nested call. that means that 648 * if the first layer chooses the same bucket 649 * in a different position, we will tend to 650 * choose a different item in that bucket. 651 * this will involve more devices in data 652 * movement and tend to distribute the load. 653 */ 654 r = rep + parent_r; 655 656 /* be careful */ 657 if (in->alg == CRUSH_BUCKET_UNIFORM && 658 in->size % numrep == 0) 659 /* r'=r+(n+1)*f_total */ 660 r += (numrep+1) * ftotal; 661 else 662 /* r' = r + n*f_total */ 663 r += numrep * ftotal; 664 665 /* bucket choose */ 666 if (in->size == 0) { 667 dprintk(" empty bucket\n"); 668 break; 669 } 670 671 item = crush_bucket_choose(in, x, r); 672 if (item >= map->max_devices) { 673 dprintk(" bad item %d\n", item); 674 out[rep] = CRUSH_ITEM_NONE; 675 if (out2) 676 out2[rep] = CRUSH_ITEM_NONE; 677 left--; 678 break; 679 } 680 681 /* desired type? */ 682 if (item < 0) 683 itemtype = map->buckets[-1-item]->type; 684 else 685 itemtype = 0; 686 dprintk(" item %d type %d\n", item, itemtype); 687 688 /* keep going? */ 689 if (itemtype != type) { 690 if (item >= 0 || 691 (-1-item) >= map->max_buckets) { 692 dprintk(" bad item type %d\n", type); 693 out[rep] = CRUSH_ITEM_NONE; 694 if (out2) 695 out2[rep] = 696 CRUSH_ITEM_NONE; 697 left--; 698 break; 699 } 700 in = map->buckets[-1-item]; 701 continue; 702 } 703 704 /* collision? */ 705 collide = 0; 706 for (i = outpos; i < endpos; i++) { 707 if (out[i] == item) { 708 collide = 1; 709 break; 710 } 711 } 712 if (collide) 713 break; 714 715 if (recurse_to_leaf) { 716 if (item < 0) { 717 crush_choose_indep(map, 718 map->buckets[-1-item], 719 weight, weight_max, 720 x, 1, numrep, 0, 721 out2, rep, 722 recurse_tries, 0, 723 0, NULL, r); 724 if (out2[rep] == CRUSH_ITEM_NONE) { 725 /* placed nothing; no leaf */ 726 break; 727 } 728 } else { 729 /* we already have a leaf! */ 730 out2[rep] = item; 731 } 732 } 733 734 /* out? */ 735 if (itemtype == 0 && 736 is_out(map, weight, weight_max, item, x)) 737 break; 738 739 /* yay! */ 740 out[rep] = item; 741 left--; 742 break; 743 } 744 } 745 } 746 for (rep = outpos; rep < endpos; rep++) { 747 if (out[rep] == CRUSH_ITEM_UNDEF) { 748 out[rep] = CRUSH_ITEM_NONE; 749 } 750 if (out2 && out2[rep] == CRUSH_ITEM_UNDEF) { 751 out2[rep] = CRUSH_ITEM_NONE; 752 } 753 } 754 #ifndef __KERNEL__ 755 if (map->choose_tries && ftotal <= map->choose_total_tries) 756 map->choose_tries[ftotal]++; 757 #endif 758 #ifdef DEBUG_INDEP 759 if (out2) { 760 dprintk("%u %d a: ", ftotal, left); 761 for (rep = outpos; rep < endpos; rep++) { 762 dprintk(" %d", out[rep]); 763 } 764 dprintk("\n"); 765 dprintk("%u %d b: ", ftotal, left); 766 for (rep = outpos; rep < endpos; rep++) { 767 dprintk(" %d", out2[rep]); 768 } 769 dprintk("\n"); 770 } 771 #endif 772 } 773 774 /** 775 * crush_do_rule - calculate a mapping with the given input and rule 776 * @map: the crush_map 777 * @ruleno: the rule id 778 * @x: hash input 779 * @result: pointer to result vector 780 * @result_max: maximum result size 781 * @weight: weight vector (for map leaves) 782 * @weight_max: size of weight vector 783 * @scratch: scratch vector for private use; must be >= 3 * result_max 784 */ 785 int crush_do_rule(const struct crush_map *map, 786 int ruleno, int x, int *result, int result_max, 787 const __u32 *weight, int weight_max, 788 int *scratch) 789 { 790 int result_len; 791 int *a = scratch; 792 int *b = scratch + result_max; 793 int *c = scratch + result_max*2; 794 int recurse_to_leaf; 795 int *w; 796 int wsize = 0; 797 int *o; 798 int osize; 799 int *tmp; 800 struct crush_rule *rule; 801 __u32 step; 802 int i, j; 803 int numrep; 804 int out_size; 805 /* 806 * the original choose_total_tries value was off by one (it 807 * counted "retries" and not "tries"). add one. 808 */ 809 int choose_tries = map->choose_total_tries + 1; 810 int choose_leaf_tries = 0; 811 /* 812 * the local tries values were counted as "retries", though, 813 * and need no adjustment 814 */ 815 int choose_local_retries = map->choose_local_tries; 816 int choose_local_fallback_retries = map->choose_local_fallback_tries; 817 818 int vary_r = map->chooseleaf_vary_r; 819 820 if ((__u32)ruleno >= map->max_rules) { 821 dprintk(" bad ruleno %d\n", ruleno); 822 return 0; 823 } 824 825 rule = map->rules[ruleno]; 826 result_len = 0; 827 w = a; 828 o = b; 829 830 for (step = 0; step < rule->len; step++) { 831 int firstn = 0; 832 struct crush_rule_step *curstep = &rule->steps[step]; 833 834 switch (curstep->op) { 835 case CRUSH_RULE_TAKE: 836 if ((curstep->arg1 >= 0 && 837 curstep->arg1 < map->max_devices) || 838 (-1-curstep->arg1 < map->max_buckets && 839 map->buckets[-1-curstep->arg1])) { 840 w[0] = curstep->arg1; 841 wsize = 1; 842 } else { 843 dprintk(" bad take value %d\n", curstep->arg1); 844 } 845 break; 846 847 case CRUSH_RULE_SET_CHOOSE_TRIES: 848 if (curstep->arg1 > 0) 849 choose_tries = curstep->arg1; 850 break; 851 852 case CRUSH_RULE_SET_CHOOSELEAF_TRIES: 853 if (curstep->arg1 > 0) 854 choose_leaf_tries = curstep->arg1; 855 break; 856 857 case CRUSH_RULE_SET_CHOOSE_LOCAL_TRIES: 858 if (curstep->arg1 >= 0) 859 choose_local_retries = curstep->arg1; 860 break; 861 862 case CRUSH_RULE_SET_CHOOSE_LOCAL_FALLBACK_TRIES: 863 if (curstep->arg1 >= 0) 864 choose_local_fallback_retries = curstep->arg1; 865 break; 866 867 case CRUSH_RULE_SET_CHOOSELEAF_VARY_R: 868 if (curstep->arg1 >= 0) 869 vary_r = curstep->arg1; 870 break; 871 872 case CRUSH_RULE_CHOOSELEAF_FIRSTN: 873 case CRUSH_RULE_CHOOSE_FIRSTN: 874 firstn = 1; 875 /* fall through */ 876 case CRUSH_RULE_CHOOSELEAF_INDEP: 877 case CRUSH_RULE_CHOOSE_INDEP: 878 if (wsize == 0) 879 break; 880 881 recurse_to_leaf = 882 curstep->op == 883 CRUSH_RULE_CHOOSELEAF_FIRSTN || 884 curstep->op == 885 CRUSH_RULE_CHOOSELEAF_INDEP; 886 887 /* reset output */ 888 osize = 0; 889 890 for (i = 0; i < wsize; i++) { 891 /* 892 * see CRUSH_N, CRUSH_N_MINUS macros. 893 * basically, numrep <= 0 means relative to 894 * the provided result_max 895 */ 896 numrep = curstep->arg1; 897 if (numrep <= 0) { 898 numrep += result_max; 899 if (numrep <= 0) 900 continue; 901 } 902 j = 0; 903 if (firstn) { 904 int recurse_tries; 905 if (choose_leaf_tries) 906 recurse_tries = 907 choose_leaf_tries; 908 else if (map->chooseleaf_descend_once) 909 recurse_tries = 1; 910 else 911 recurse_tries = choose_tries; 912 osize += crush_choose_firstn( 913 map, 914 map->buckets[-1-w[i]], 915 weight, weight_max, 916 x, numrep, 917 curstep->arg2, 918 o+osize, j, 919 result_max-osize, 920 choose_tries, 921 recurse_tries, 922 choose_local_retries, 923 choose_local_fallback_retries, 924 recurse_to_leaf, 925 vary_r, 926 c+osize, 927 0); 928 } else { 929 out_size = ((numrep < (result_max-osize)) ? 930 numrep : (result_max-osize)); 931 crush_choose_indep( 932 map, 933 map->buckets[-1-w[i]], 934 weight, weight_max, 935 x, out_size, numrep, 936 curstep->arg2, 937 o+osize, j, 938 choose_tries, 939 choose_leaf_tries ? 940 choose_leaf_tries : 1, 941 recurse_to_leaf, 942 c+osize, 943 0); 944 osize += out_size; 945 } 946 } 947 948 if (recurse_to_leaf) 949 /* copy final _leaf_ values to output set */ 950 memcpy(o, c, osize*sizeof(*o)); 951 952 /* swap o and w arrays */ 953 tmp = o; 954 o = w; 955 w = tmp; 956 wsize = osize; 957 break; 958 959 960 case CRUSH_RULE_EMIT: 961 for (i = 0; i < wsize && result_len < result_max; i++) { 962 result[result_len] = w[i]; 963 result_len++; 964 } 965 wsize = 0; 966 break; 967 968 default: 969 dprintk(" unknown op %d at step %d\n", 970 curstep->op, step); 971 break; 972 } 973 } 974 return result_len; 975 } 976