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 */ 42 int 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 */ 74 static 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]; 128 out: 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 */ 135 static 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 */ 142 static 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 */ 169 static 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 } 178 179 static int left(int x) 180 { 181 int h = height(x); 182 return x - (1 << (h-1)); 183 } 184 185 static int right(int x) 186 { 187 int h = height(x); 188 return x + (1 << (h-1)); 189 } 190 191 static int terminal(int x) 192 { 193 return x & 1; 194 } 195 196 static 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 */ 227 228 static 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) */ 249 static __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 * http://en.wikipedia.org/wiki/Exponential_distribution#Distribution_of_the_minimum_of_exponential_random_variables 302 * 303 */ 304 305 static __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 } 316 317 static __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 } 325 326 static 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 } 374 375 376 static 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 */ 413 static 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 * @bucket: the bucket we are choose an item from 433 * @x: crush input value 434 * @numrep: the number of items to choose 435 * @type: the type of item to choose 436 * @out: pointer to output vector 437 * @outpos: our position in that vector 438 * @out_size: size of the out vector 439 * @tries: number of attempts to make 440 * @recurse_tries: number of attempts to have recursive chooseleaf make 441 * @local_retries: localized retries 442 * @local_fallback_retries: localized fallback retries 443 * @recurse_to_leaf: true if we want one device under each item of given type (chooseleaf instead of choose) 444 * @stable: stable mode starts rep=0 in the recursive call for all replicas 445 * @vary_r: pass r to recursive calls 446 * @out2: second output vector for leaf items (if @recurse_to_leaf) 447 * @parent_r: r value passed from the parent 448 */ 449 static int crush_choose_firstn(const struct crush_map *map, 450 struct crush_work *work, 451 const struct crush_bucket *bucket, 452 const __u32 *weight, int weight_max, 453 int x, int numrep, int type, 454 int *out, int outpos, 455 int out_size, 456 unsigned int tries, 457 unsigned int recurse_tries, 458 unsigned int local_retries, 459 unsigned int local_fallback_retries, 460 int recurse_to_leaf, 461 unsigned int vary_r, 462 unsigned int stable, 463 int *out2, 464 int parent_r, 465 const struct crush_choose_arg *choose_args) 466 { 467 int rep; 468 unsigned int ftotal, flocal; 469 int retry_descent, retry_bucket, skip_rep; 470 const struct crush_bucket *in = bucket; 471 int r; 472 int i; 473 int item = 0; 474 int itemtype; 475 int collide, reject; 476 int count = out_size; 477 478 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", 479 recurse_to_leaf ? "_LEAF" : "", 480 bucket->id, x, outpos, numrep, 481 tries, recurse_tries, local_retries, local_fallback_retries, 482 parent_r, stable); 483 484 for (rep = stable ? 0 : outpos; rep < numrep && count > 0 ; rep++) { 485 /* keep trying until we get a non-out, non-colliding item */ 486 ftotal = 0; 487 skip_rep = 0; 488 do { 489 retry_descent = 0; 490 in = bucket; /* initial bucket */ 491 492 /* choose through intervening buckets */ 493 flocal = 0; 494 do { 495 collide = 0; 496 retry_bucket = 0; 497 r = rep + parent_r; 498 /* r' = r + f_total */ 499 r += ftotal; 500 501 /* bucket choose */ 502 if (in->size == 0) { 503 reject = 1; 504 goto reject; 505 } 506 if (local_fallback_retries > 0 && 507 flocal >= (in->size>>1) && 508 flocal > local_fallback_retries) 509 item = bucket_perm_choose( 510 in, work->work[-1-in->id], 511 x, r); 512 else 513 item = crush_bucket_choose( 514 in, work->work[-1-in->id], 515 x, r, 516 (choose_args ? 517 &choose_args[-1-in->id] : 0), 518 outpos); 519 if (item >= map->max_devices) { 520 dprintk(" bad item %d\n", item); 521 skip_rep = 1; 522 break; 523 } 524 525 /* desired type? */ 526 if (item < 0) 527 itemtype = map->buckets[-1-item]->type; 528 else 529 itemtype = 0; 530 dprintk(" item %d type %d\n", item, itemtype); 531 532 /* keep going? */ 533 if (itemtype != type) { 534 if (item >= 0 || 535 (-1-item) >= map->max_buckets) { 536 dprintk(" bad item type %d\n", type); 537 skip_rep = 1; 538 break; 539 } 540 in = map->buckets[-1-item]; 541 retry_bucket = 1; 542 continue; 543 } 544 545 /* collision? */ 546 for (i = 0; i < outpos; i++) { 547 if (out[i] == item) { 548 collide = 1; 549 break; 550 } 551 } 552 553 reject = 0; 554 if (!collide && recurse_to_leaf) { 555 if (item < 0) { 556 int sub_r; 557 if (vary_r) 558 sub_r = r >> (vary_r-1); 559 else 560 sub_r = 0; 561 if (crush_choose_firstn( 562 map, 563 work, 564 map->buckets[-1-item], 565 weight, weight_max, 566 x, stable ? 1 : outpos+1, 0, 567 out2, outpos, count, 568 recurse_tries, 0, 569 local_retries, 570 local_fallback_retries, 571 0, 572 vary_r, 573 stable, 574 NULL, 575 sub_r, 576 choose_args) <= outpos) 577 /* didn't get leaf */ 578 reject = 1; 579 } else { 580 /* we already have a leaf! */ 581 out2[outpos] = item; 582 } 583 } 584 585 if (!reject && !collide) { 586 /* out? */ 587 if (itemtype == 0) 588 reject = is_out(map, weight, 589 weight_max, 590 item, x); 591 } 592 593 reject: 594 if (reject || collide) { 595 ftotal++; 596 flocal++; 597 598 if (collide && flocal <= local_retries) 599 /* retry locally a few times */ 600 retry_bucket = 1; 601 else if (local_fallback_retries > 0 && 602 flocal <= in->size + local_fallback_retries) 603 /* exhaustive bucket search */ 604 retry_bucket = 1; 605 else if (ftotal < tries) 606 /* then retry descent */ 607 retry_descent = 1; 608 else 609 /* else give up */ 610 skip_rep = 1; 611 dprintk(" reject %d collide %d " 612 "ftotal %u flocal %u\n", 613 reject, collide, ftotal, 614 flocal); 615 } 616 } while (retry_bucket); 617 } while (retry_descent); 618 619 if (skip_rep) { 620 dprintk("skip rep\n"); 621 continue; 622 } 623 624 dprintk("CHOOSE got %d\n", item); 625 out[outpos] = item; 626 outpos++; 627 count--; 628 #ifndef __KERNEL__ 629 if (map->choose_tries && ftotal <= map->choose_total_tries) 630 map->choose_tries[ftotal]++; 631 #endif 632 } 633 634 dprintk("CHOOSE returns %d\n", outpos); 635 return outpos; 636 } 637 638 639 /** 640 * crush_choose_indep: alternative breadth-first positionally stable mapping 641 * 642 */ 643 static void crush_choose_indep(const struct crush_map *map, 644 struct crush_work *work, 645 const struct crush_bucket *bucket, 646 const __u32 *weight, int weight_max, 647 int x, int left, int numrep, int type, 648 int *out, int outpos, 649 unsigned int tries, 650 unsigned int recurse_tries, 651 int recurse_to_leaf, 652 int *out2, 653 int parent_r, 654 const struct crush_choose_arg *choose_args) 655 { 656 const struct crush_bucket *in = bucket; 657 int endpos = outpos + left; 658 int rep; 659 unsigned int ftotal; 660 int r; 661 int i; 662 int item = 0; 663 int itemtype; 664 int collide; 665 666 dprintk("CHOOSE%s INDEP bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "", 667 bucket->id, x, outpos, numrep); 668 669 /* initially my result is undefined */ 670 for (rep = outpos; rep < endpos; rep++) { 671 out[rep] = CRUSH_ITEM_UNDEF; 672 if (out2) 673 out2[rep] = CRUSH_ITEM_UNDEF; 674 } 675 676 for (ftotal = 0; left > 0 && ftotal < tries; ftotal++) { 677 #ifdef DEBUG_INDEP 678 if (out2 && ftotal) { 679 dprintk("%u %d a: ", ftotal, left); 680 for (rep = outpos; rep < endpos; rep++) { 681 dprintk(" %d", out[rep]); 682 } 683 dprintk("\n"); 684 dprintk("%u %d b: ", ftotal, left); 685 for (rep = outpos; rep < endpos; rep++) { 686 dprintk(" %d", out2[rep]); 687 } 688 dprintk("\n"); 689 } 690 #endif 691 for (rep = outpos; rep < endpos; rep++) { 692 if (out[rep] != CRUSH_ITEM_UNDEF) 693 continue; 694 695 in = bucket; /* initial bucket */ 696 697 /* choose through intervening buckets */ 698 for (;;) { 699 /* note: we base the choice on the position 700 * even in the nested call. that means that 701 * if the first layer chooses the same bucket 702 * in a different position, we will tend to 703 * choose a different item in that bucket. 704 * this will involve more devices in data 705 * movement and tend to distribute the load. 706 */ 707 r = rep + parent_r; 708 709 /* be careful */ 710 if (in->alg == CRUSH_BUCKET_UNIFORM && 711 in->size % numrep == 0) 712 /* r'=r+(n+1)*f_total */ 713 r += (numrep+1) * ftotal; 714 else 715 /* r' = r + n*f_total */ 716 r += numrep * ftotal; 717 718 /* bucket choose */ 719 if (in->size == 0) { 720 dprintk(" empty bucket\n"); 721 break; 722 } 723 724 item = crush_bucket_choose( 725 in, work->work[-1-in->id], 726 x, r, 727 (choose_args ? 728 &choose_args[-1-in->id] : 0), 729 outpos); 730 if (item >= map->max_devices) { 731 dprintk(" bad item %d\n", item); 732 out[rep] = CRUSH_ITEM_NONE; 733 if (out2) 734 out2[rep] = CRUSH_ITEM_NONE; 735 left--; 736 break; 737 } 738 739 /* desired type? */ 740 if (item < 0) 741 itemtype = map->buckets[-1-item]->type; 742 else 743 itemtype = 0; 744 dprintk(" item %d type %d\n", item, itemtype); 745 746 /* keep going? */ 747 if (itemtype != type) { 748 if (item >= 0 || 749 (-1-item) >= map->max_buckets) { 750 dprintk(" bad item type %d\n", type); 751 out[rep] = CRUSH_ITEM_NONE; 752 if (out2) 753 out2[rep] = 754 CRUSH_ITEM_NONE; 755 left--; 756 break; 757 } 758 in = map->buckets[-1-item]; 759 continue; 760 } 761 762 /* collision? */ 763 collide = 0; 764 for (i = outpos; i < endpos; i++) { 765 if (out[i] == item) { 766 collide = 1; 767 break; 768 } 769 } 770 if (collide) 771 break; 772 773 if (recurse_to_leaf) { 774 if (item < 0) { 775 crush_choose_indep( 776 map, 777 work, 778 map->buckets[-1-item], 779 weight, weight_max, 780 x, 1, numrep, 0, 781 out2, rep, 782 recurse_tries, 0, 783 0, NULL, r, 784 choose_args); 785 if (out2[rep] == CRUSH_ITEM_NONE) { 786 /* placed nothing; no leaf */ 787 break; 788 } 789 } else { 790 /* we already have a leaf! */ 791 out2[rep] = item; 792 } 793 } 794 795 /* out? */ 796 if (itemtype == 0 && 797 is_out(map, weight, weight_max, item, x)) 798 break; 799 800 /* yay! */ 801 out[rep] = item; 802 left--; 803 break; 804 } 805 } 806 } 807 for (rep = outpos; rep < endpos; rep++) { 808 if (out[rep] == CRUSH_ITEM_UNDEF) { 809 out[rep] = CRUSH_ITEM_NONE; 810 } 811 if (out2 && out2[rep] == CRUSH_ITEM_UNDEF) { 812 out2[rep] = CRUSH_ITEM_NONE; 813 } 814 } 815 #ifndef __KERNEL__ 816 if (map->choose_tries && ftotal <= map->choose_total_tries) 817 map->choose_tries[ftotal]++; 818 #endif 819 #ifdef DEBUG_INDEP 820 if (out2) { 821 dprintk("%u %d a: ", ftotal, left); 822 for (rep = outpos; rep < endpos; rep++) { 823 dprintk(" %d", out[rep]); 824 } 825 dprintk("\n"); 826 dprintk("%u %d b: ", ftotal, left); 827 for (rep = outpos; rep < endpos; rep++) { 828 dprintk(" %d", out2[rep]); 829 } 830 dprintk("\n"); 831 } 832 #endif 833 } 834 835 836 /* 837 * This takes a chunk of memory and sets it up to be a shiny new 838 * working area for a CRUSH placement computation. It must be called 839 * on any newly allocated memory before passing it in to 840 * crush_do_rule. It may be used repeatedly after that, so long as the 841 * map has not changed. If the map /has/ changed, you must make sure 842 * the working size is no smaller than what was allocated and re-run 843 * crush_init_workspace. 844 * 845 * If you do retain the working space between calls to crush, make it 846 * thread-local. 847 */ 848 void crush_init_workspace(const struct crush_map *map, void *v) 849 { 850 struct crush_work *w = v; 851 __s32 b; 852 853 /* 854 * We work by moving through the available space and setting 855 * values and pointers as we go. 856 * 857 * It's a bit like Forth's use of the 'allot' word since we 858 * set the pointer first and then reserve the space for it to 859 * point to by incrementing the point. 860 */ 861 v += sizeof(struct crush_work); 862 w->work = v; 863 v += map->max_buckets * sizeof(struct crush_work_bucket *); 864 for (b = 0; b < map->max_buckets; ++b) { 865 if (!map->buckets[b]) 866 continue; 867 868 w->work[b] = v; 869 switch (map->buckets[b]->alg) { 870 default: 871 v += sizeof(struct crush_work_bucket); 872 break; 873 } 874 w->work[b]->perm_x = 0; 875 w->work[b]->perm_n = 0; 876 w->work[b]->perm = v; 877 v += map->buckets[b]->size * sizeof(__u32); 878 } 879 BUG_ON(v - (void *)w != map->working_size); 880 } 881 882 /** 883 * crush_do_rule - calculate a mapping with the given input and rule 884 * @map: the crush_map 885 * @ruleno: the rule id 886 * @x: hash input 887 * @result: pointer to result vector 888 * @result_max: maximum result size 889 * @weight: weight vector (for map leaves) 890 * @weight_max: size of weight vector 891 * @cwin: pointer to at least crush_work_size() bytes of memory 892 * @choose_args: weights and ids for each known bucket 893 */ 894 int crush_do_rule(const struct crush_map *map, 895 int ruleno, int x, int *result, int result_max, 896 const __u32 *weight, int weight_max, 897 void *cwin, const struct crush_choose_arg *choose_args) 898 { 899 int result_len; 900 struct crush_work *cw = cwin; 901 int *a = cwin + map->working_size; 902 int *b = a + result_max; 903 int *c = b + result_max; 904 int *w = a; 905 int *o = b; 906 int recurse_to_leaf; 907 int wsize = 0; 908 int osize; 909 int *tmp; 910 const struct crush_rule *rule; 911 __u32 step; 912 int i, j; 913 int numrep; 914 int out_size; 915 /* 916 * the original choose_total_tries value was off by one (it 917 * counted "retries" and not "tries"). add one. 918 */ 919 int choose_tries = map->choose_total_tries + 1; 920 int choose_leaf_tries = 0; 921 /* 922 * the local tries values were counted as "retries", though, 923 * and need no adjustment 924 */ 925 int choose_local_retries = map->choose_local_tries; 926 int choose_local_fallback_retries = map->choose_local_fallback_tries; 927 928 int vary_r = map->chooseleaf_vary_r; 929 int stable = map->chooseleaf_stable; 930 931 if ((__u32)ruleno >= map->max_rules) { 932 dprintk(" bad ruleno %d\n", ruleno); 933 return 0; 934 } 935 936 rule = map->rules[ruleno]; 937 result_len = 0; 938 939 for (step = 0; step < rule->len; step++) { 940 int firstn = 0; 941 const struct crush_rule_step *curstep = &rule->steps[step]; 942 943 switch (curstep->op) { 944 case CRUSH_RULE_TAKE: 945 if ((curstep->arg1 >= 0 && 946 curstep->arg1 < map->max_devices) || 947 (-1-curstep->arg1 >= 0 && 948 -1-curstep->arg1 < map->max_buckets && 949 map->buckets[-1-curstep->arg1])) { 950 w[0] = curstep->arg1; 951 wsize = 1; 952 } else { 953 dprintk(" bad take value %d\n", curstep->arg1); 954 } 955 break; 956 957 case CRUSH_RULE_SET_CHOOSE_TRIES: 958 if (curstep->arg1 > 0) 959 choose_tries = curstep->arg1; 960 break; 961 962 case CRUSH_RULE_SET_CHOOSELEAF_TRIES: 963 if (curstep->arg1 > 0) 964 choose_leaf_tries = curstep->arg1; 965 break; 966 967 case CRUSH_RULE_SET_CHOOSE_LOCAL_TRIES: 968 if (curstep->arg1 >= 0) 969 choose_local_retries = curstep->arg1; 970 break; 971 972 case CRUSH_RULE_SET_CHOOSE_LOCAL_FALLBACK_TRIES: 973 if (curstep->arg1 >= 0) 974 choose_local_fallback_retries = curstep->arg1; 975 break; 976 977 case CRUSH_RULE_SET_CHOOSELEAF_VARY_R: 978 if (curstep->arg1 >= 0) 979 vary_r = curstep->arg1; 980 break; 981 982 case CRUSH_RULE_SET_CHOOSELEAF_STABLE: 983 if (curstep->arg1 >= 0) 984 stable = curstep->arg1; 985 break; 986 987 case CRUSH_RULE_CHOOSELEAF_FIRSTN: 988 case CRUSH_RULE_CHOOSE_FIRSTN: 989 firstn = 1; 990 /* fall through */ 991 case CRUSH_RULE_CHOOSELEAF_INDEP: 992 case CRUSH_RULE_CHOOSE_INDEP: 993 if (wsize == 0) 994 break; 995 996 recurse_to_leaf = 997 curstep->op == 998 CRUSH_RULE_CHOOSELEAF_FIRSTN || 999 curstep->op == 1000 CRUSH_RULE_CHOOSELEAF_INDEP; 1001 1002 /* reset output */ 1003 osize = 0; 1004 1005 for (i = 0; i < wsize; i++) { 1006 int bno; 1007 numrep = curstep->arg1; 1008 if (numrep <= 0) { 1009 numrep += result_max; 1010 if (numrep <= 0) 1011 continue; 1012 } 1013 j = 0; 1014 /* make sure bucket id is valid */ 1015 bno = -1 - w[i]; 1016 if (bno < 0 || bno >= map->max_buckets) { 1017 /* w[i] is probably CRUSH_ITEM_NONE */ 1018 dprintk(" bad w[i] %d\n", w[i]); 1019 continue; 1020 } 1021 if (firstn) { 1022 int recurse_tries; 1023 if (choose_leaf_tries) 1024 recurse_tries = 1025 choose_leaf_tries; 1026 else if (map->chooseleaf_descend_once) 1027 recurse_tries = 1; 1028 else 1029 recurse_tries = choose_tries; 1030 osize += crush_choose_firstn( 1031 map, 1032 cw, 1033 map->buckets[bno], 1034 weight, weight_max, 1035 x, numrep, 1036 curstep->arg2, 1037 o+osize, j, 1038 result_max-osize, 1039 choose_tries, 1040 recurse_tries, 1041 choose_local_retries, 1042 choose_local_fallback_retries, 1043 recurse_to_leaf, 1044 vary_r, 1045 stable, 1046 c+osize, 1047 0, 1048 choose_args); 1049 } else { 1050 out_size = ((numrep < (result_max-osize)) ? 1051 numrep : (result_max-osize)); 1052 crush_choose_indep( 1053 map, 1054 cw, 1055 map->buckets[bno], 1056 weight, weight_max, 1057 x, out_size, numrep, 1058 curstep->arg2, 1059 o+osize, j, 1060 choose_tries, 1061 choose_leaf_tries ? 1062 choose_leaf_tries : 1, 1063 recurse_to_leaf, 1064 c+osize, 1065 0, 1066 choose_args); 1067 osize += out_size; 1068 } 1069 } 1070 1071 if (recurse_to_leaf) 1072 /* copy final _leaf_ values to output set */ 1073 memcpy(o, c, osize*sizeof(*o)); 1074 1075 /* swap o and w arrays */ 1076 tmp = o; 1077 o = w; 1078 w = tmp; 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 } 1100