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 */
crush_find_rule(const struct crush_map * map,int ruleset,int type,int size)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 */
bucket_perm_choose(struct crush_bucket * bucket,int x,int r)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 */
bucket_uniform_choose(struct crush_bucket_uniform * bucket,int x,int r)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 */
bucket_list_choose(struct crush_bucket_list * bucket,int x,int r)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 */
height(int n)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
left(int x)176 static int left(int x)
177 {
178 int h = height(x);
179 return x - (1 << (h-1));
180 }
181
right(int x)182 static int right(int x)
183 {
184 int h = height(x);
185 return x + (1 << (h-1));
186 }
187
terminal(int x)188 static int terminal(int x)
189 {
190 return x & 1;
191 }
192
bucket_tree_choose(struct crush_bucket_tree * bucket,int x,int r)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
bucket_straw_choose(struct crush_bucket_straw * bucket,int x,int r)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) */
crush_ln(unsigned int xin)246 static __u64 crush_ln(unsigned int xin)
247 {
248 unsigned int x = xin;
249 int iexpon, index1, index2;
250 __u64 RH, LH, LL, xl64, result;
251
252 x++;
253
254 /* normalize input */
255 iexpon = 15;
256
257 /*
258 * figure out number of bits we need to shift and
259 * do it in one step instead of iteratively
260 */
261 if (!(x & 0x18000)) {
262 int bits = __builtin_clz(x & 0x1FFFF) - 16;
263 x <<= bits;
264 iexpon = 15 - bits;
265 }
266
267 index1 = (x >> 8) << 1;
268 /* RH ~ 2^56/index1 */
269 RH = __RH_LH_tbl[index1 - 256];
270 /* LH ~ 2^48 * log2(index1/256) */
271 LH = __RH_LH_tbl[index1 + 1 - 256];
272
273 /* RH*x ~ 2^48 * (2^15 + xf), xf<2^8 */
274 xl64 = (__s64)x * RH;
275 xl64 >>= 48;
276
277 result = iexpon;
278 result <<= (12 + 32);
279
280 index2 = xl64 & 0xff;
281 /* LL ~ 2^48*log2(1.0+index2/2^15) */
282 LL = __LL_tbl[index2];
283
284 LH = LH + LL;
285
286 LH >>= (48 - 12 - 32);
287 result += LH;
288
289 return result;
290 }
291
292
293 /*
294 * straw2
295 *
296 * for reference, see:
297 *
298 * http://en.wikipedia.org/wiki/Exponential_distribution#Distribution_of_the_minimum_of_exponential_random_variables
299 *
300 */
301
bucket_straw2_choose(struct crush_bucket_straw2 * bucket,int x,int r)302 static int bucket_straw2_choose(struct crush_bucket_straw2 *bucket,
303 int x, int r)
304 {
305 unsigned int i, high = 0;
306 unsigned int u;
307 unsigned int w;
308 __s64 ln, draw, high_draw = 0;
309
310 for (i = 0; i < bucket->h.size; i++) {
311 w = bucket->item_weights[i];
312 if (w) {
313 u = crush_hash32_3(bucket->h.hash, x,
314 bucket->h.items[i], r);
315 u &= 0xffff;
316
317 /*
318 * for some reason slightly less than 0x10000 produces
319 * a slightly more accurate distribution... probably a
320 * rounding effect.
321 *
322 * the natural log lookup table maps [0,0xffff]
323 * (corresponding to real numbers [1/0x10000, 1] to
324 * [0, 0xffffffffffff] (corresponding to real numbers
325 * [-11.090355,0]).
326 */
327 ln = crush_ln(u) - 0x1000000000000ll;
328
329 /*
330 * divide by 16.16 fixed-point weight. note
331 * that the ln value is negative, so a larger
332 * weight means a larger (less negative) value
333 * for draw.
334 */
335 draw = div64_s64(ln, w);
336 } else {
337 draw = S64_MIN;
338 }
339
340 if (i == 0 || draw > high_draw) {
341 high = i;
342 high_draw = draw;
343 }
344 }
345 return bucket->h.items[high];
346 }
347
348
crush_bucket_choose(struct crush_bucket * in,int x,int r)349 static int crush_bucket_choose(struct crush_bucket *in, int x, int r)
350 {
351 dprintk(" crush_bucket_choose %d x=%d r=%d\n", in->id, x, r);
352 BUG_ON(in->size == 0);
353 switch (in->alg) {
354 case CRUSH_BUCKET_UNIFORM:
355 return bucket_uniform_choose((struct crush_bucket_uniform *)in,
356 x, r);
357 case CRUSH_BUCKET_LIST:
358 return bucket_list_choose((struct crush_bucket_list *)in,
359 x, r);
360 case CRUSH_BUCKET_TREE:
361 return bucket_tree_choose((struct crush_bucket_tree *)in,
362 x, r);
363 case CRUSH_BUCKET_STRAW:
364 return bucket_straw_choose((struct crush_bucket_straw *)in,
365 x, r);
366 case CRUSH_BUCKET_STRAW2:
367 return bucket_straw2_choose((struct crush_bucket_straw2 *)in,
368 x, r);
369 default:
370 dprintk("unknown bucket %d alg %d\n", in->id, in->alg);
371 return in->items[0];
372 }
373 }
374
375
376 /*
377 * true if device is marked "out" (failed, fully offloaded)
378 * of the cluster
379 */
is_out(const struct crush_map * map,const __u32 * weight,int weight_max,int item,int x)380 static int is_out(const struct crush_map *map,
381 const __u32 *weight, int weight_max,
382 int item, int x)
383 {
384 if (item >= weight_max)
385 return 1;
386 if (weight[item] >= 0x10000)
387 return 0;
388 if (weight[item] == 0)
389 return 1;
390 if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff)
391 < weight[item])
392 return 0;
393 return 1;
394 }
395
396 /**
397 * crush_choose_firstn - choose numrep distinct items of given type
398 * @map: the crush_map
399 * @bucket: the bucket we are choose an item from
400 * @x: crush input value
401 * @numrep: the number of items to choose
402 * @type: the type of item to choose
403 * @out: pointer to output vector
404 * @outpos: our position in that vector
405 * @out_size: size of the out vector
406 * @tries: number of attempts to make
407 * @recurse_tries: number of attempts to have recursive chooseleaf make
408 * @local_retries: localized retries
409 * @local_fallback_retries: localized fallback retries
410 * @recurse_to_leaf: true if we want one device under each item of given type (chooseleaf instead of choose)
411 * @stable: stable mode starts rep=0 in the recursive call for all replicas
412 * @vary_r: pass r to recursive calls
413 * @out2: second output vector for leaf items (if @recurse_to_leaf)
414 * @parent_r: r value passed from the parent
415 */
crush_choose_firstn(const struct crush_map * map,struct crush_bucket * bucket,const __u32 * weight,int weight_max,int x,int numrep,int type,int * out,int outpos,int out_size,unsigned int tries,unsigned int recurse_tries,unsigned int local_retries,unsigned int local_fallback_retries,int recurse_to_leaf,unsigned int vary_r,unsigned int stable,int * out2,int parent_r)416 static int crush_choose_firstn(const struct crush_map *map,
417 struct crush_bucket *bucket,
418 const __u32 *weight, int weight_max,
419 int x, int numrep, int type,
420 int *out, int outpos,
421 int out_size,
422 unsigned int tries,
423 unsigned int recurse_tries,
424 unsigned int local_retries,
425 unsigned int local_fallback_retries,
426 int recurse_to_leaf,
427 unsigned int vary_r,
428 unsigned int stable,
429 int *out2,
430 int parent_r)
431 {
432 int rep;
433 unsigned int ftotal, flocal;
434 int retry_descent, retry_bucket, skip_rep;
435 struct crush_bucket *in = bucket;
436 int r;
437 int i;
438 int item = 0;
439 int itemtype;
440 int collide, reject;
441 int count = out_size;
442
443 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",
444 recurse_to_leaf ? "_LEAF" : "",
445 bucket->id, x, outpos, numrep,
446 tries, recurse_tries, local_retries, local_fallback_retries,
447 parent_r, stable);
448
449 for (rep = stable ? 0 : outpos; rep < numrep && count > 0 ; rep++) {
450 /* keep trying until we get a non-out, non-colliding item */
451 ftotal = 0;
452 skip_rep = 0;
453 do {
454 retry_descent = 0;
455 in = bucket; /* initial bucket */
456
457 /* choose through intervening buckets */
458 flocal = 0;
459 do {
460 collide = 0;
461 retry_bucket = 0;
462 r = rep + parent_r;
463 /* r' = r + f_total */
464 r += ftotal;
465
466 /* bucket choose */
467 if (in->size == 0) {
468 reject = 1;
469 goto reject;
470 }
471 if (local_fallback_retries > 0 &&
472 flocal >= (in->size>>1) &&
473 flocal > local_fallback_retries)
474 item = bucket_perm_choose(in, x, r);
475 else
476 item = crush_bucket_choose(in, x, r);
477 if (item >= map->max_devices) {
478 dprintk(" bad item %d\n", item);
479 skip_rep = 1;
480 break;
481 }
482
483 /* desired type? */
484 if (item < 0)
485 itemtype = map->buckets[-1-item]->type;
486 else
487 itemtype = 0;
488 dprintk(" item %d type %d\n", item, itemtype);
489
490 /* keep going? */
491 if (itemtype != type) {
492 if (item >= 0 ||
493 (-1-item) >= map->max_buckets) {
494 dprintk(" bad item type %d\n", type);
495 skip_rep = 1;
496 break;
497 }
498 in = map->buckets[-1-item];
499 retry_bucket = 1;
500 continue;
501 }
502
503 /* collision? */
504 for (i = 0; i < outpos; i++) {
505 if (out[i] == item) {
506 collide = 1;
507 break;
508 }
509 }
510
511 reject = 0;
512 if (!collide && recurse_to_leaf) {
513 if (item < 0) {
514 int sub_r;
515 if (vary_r)
516 sub_r = r >> (vary_r-1);
517 else
518 sub_r = 0;
519 if (crush_choose_firstn(map,
520 map->buckets[-1-item],
521 weight, weight_max,
522 x, stable ? 1 : outpos+1, 0,
523 out2, outpos, count,
524 recurse_tries, 0,
525 local_retries,
526 local_fallback_retries,
527 0,
528 vary_r,
529 stable,
530 NULL,
531 sub_r) <= outpos)
532 /* didn't get leaf */
533 reject = 1;
534 } else {
535 /* we already have a leaf! */
536 out2[outpos] = item;
537 }
538 }
539
540 if (!reject) {
541 /* out? */
542 if (itemtype == 0)
543 reject = is_out(map, weight,
544 weight_max,
545 item, x);
546 else
547 reject = 0;
548 }
549
550 reject:
551 if (reject || collide) {
552 ftotal++;
553 flocal++;
554
555 if (collide && flocal <= local_retries)
556 /* retry locally a few times */
557 retry_bucket = 1;
558 else if (local_fallback_retries > 0 &&
559 flocal <= in->size + local_fallback_retries)
560 /* exhaustive bucket search */
561 retry_bucket = 1;
562 else if (ftotal < tries)
563 /* then retry descent */
564 retry_descent = 1;
565 else
566 /* else give up */
567 skip_rep = 1;
568 dprintk(" reject %d collide %d "
569 "ftotal %u flocal %u\n",
570 reject, collide, ftotal,
571 flocal);
572 }
573 } while (retry_bucket);
574 } while (retry_descent);
575
576 if (skip_rep) {
577 dprintk("skip rep\n");
578 continue;
579 }
580
581 dprintk("CHOOSE got %d\n", item);
582 out[outpos] = item;
583 outpos++;
584 count--;
585 #ifndef __KERNEL__
586 if (map->choose_tries && ftotal <= map->choose_total_tries)
587 map->choose_tries[ftotal]++;
588 #endif
589 }
590
591 dprintk("CHOOSE returns %d\n", outpos);
592 return outpos;
593 }
594
595
596 /**
597 * crush_choose_indep: alternative breadth-first positionally stable mapping
598 *
599 */
crush_choose_indep(const struct crush_map * map,struct crush_bucket * bucket,const __u32 * weight,int weight_max,int x,int left,int numrep,int type,int * out,int outpos,unsigned int tries,unsigned int recurse_tries,int recurse_to_leaf,int * out2,int parent_r)600 static void crush_choose_indep(const struct crush_map *map,
601 struct crush_bucket *bucket,
602 const __u32 *weight, int weight_max,
603 int x, int left, int numrep, int type,
604 int *out, int outpos,
605 unsigned int tries,
606 unsigned int recurse_tries,
607 int recurse_to_leaf,
608 int *out2,
609 int parent_r)
610 {
611 struct crush_bucket *in = bucket;
612 int endpos = outpos + left;
613 int rep;
614 unsigned int ftotal;
615 int r;
616 int i;
617 int item = 0;
618 int itemtype;
619 int collide;
620
621 dprintk("CHOOSE%s INDEP bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "",
622 bucket->id, x, outpos, numrep);
623
624 /* initially my result is undefined */
625 for (rep = outpos; rep < endpos; rep++) {
626 out[rep] = CRUSH_ITEM_UNDEF;
627 if (out2)
628 out2[rep] = CRUSH_ITEM_UNDEF;
629 }
630
631 for (ftotal = 0; left > 0 && ftotal < tries; ftotal++) {
632 #ifdef DEBUG_INDEP
633 if (out2 && ftotal) {
634 dprintk("%u %d a: ", ftotal, left);
635 for (rep = outpos; rep < endpos; rep++) {
636 dprintk(" %d", out[rep]);
637 }
638 dprintk("\n");
639 dprintk("%u %d b: ", ftotal, left);
640 for (rep = outpos; rep < endpos; rep++) {
641 dprintk(" %d", out2[rep]);
642 }
643 dprintk("\n");
644 }
645 #endif
646 for (rep = outpos; rep < endpos; rep++) {
647 if (out[rep] != CRUSH_ITEM_UNDEF)
648 continue;
649
650 in = bucket; /* initial bucket */
651
652 /* choose through intervening buckets */
653 for (;;) {
654 /* note: we base the choice on the position
655 * even in the nested call. that means that
656 * if the first layer chooses the same bucket
657 * in a different position, we will tend to
658 * choose a different item in that bucket.
659 * this will involve more devices in data
660 * movement and tend to distribute the load.
661 */
662 r = rep + parent_r;
663
664 /* be careful */
665 if (in->alg == CRUSH_BUCKET_UNIFORM &&
666 in->size % numrep == 0)
667 /* r'=r+(n+1)*f_total */
668 r += (numrep+1) * ftotal;
669 else
670 /* r' = r + n*f_total */
671 r += numrep * ftotal;
672
673 /* bucket choose */
674 if (in->size == 0) {
675 dprintk(" empty bucket\n");
676 break;
677 }
678
679 item = crush_bucket_choose(in, x, r);
680 if (item >= map->max_devices) {
681 dprintk(" bad item %d\n", item);
682 out[rep] = CRUSH_ITEM_NONE;
683 if (out2)
684 out2[rep] = CRUSH_ITEM_NONE;
685 left--;
686 break;
687 }
688
689 /* desired type? */
690 if (item < 0)
691 itemtype = map->buckets[-1-item]->type;
692 else
693 itemtype = 0;
694 dprintk(" item %d type %d\n", item, itemtype);
695
696 /* keep going? */
697 if (itemtype != type) {
698 if (item >= 0 ||
699 (-1-item) >= map->max_buckets) {
700 dprintk(" bad item type %d\n", type);
701 out[rep] = CRUSH_ITEM_NONE;
702 if (out2)
703 out2[rep] =
704 CRUSH_ITEM_NONE;
705 left--;
706 break;
707 }
708 in = map->buckets[-1-item];
709 continue;
710 }
711
712 /* collision? */
713 collide = 0;
714 for (i = outpos; i < endpos; i++) {
715 if (out[i] == item) {
716 collide = 1;
717 break;
718 }
719 }
720 if (collide)
721 break;
722
723 if (recurse_to_leaf) {
724 if (item < 0) {
725 crush_choose_indep(map,
726 map->buckets[-1-item],
727 weight, weight_max,
728 x, 1, numrep, 0,
729 out2, rep,
730 recurse_tries, 0,
731 0, NULL, r);
732 if (out2[rep] == CRUSH_ITEM_NONE) {
733 /* placed nothing; no leaf */
734 break;
735 }
736 } else {
737 /* we already have a leaf! */
738 out2[rep] = item;
739 }
740 }
741
742 /* out? */
743 if (itemtype == 0 &&
744 is_out(map, weight, weight_max, item, x))
745 break;
746
747 /* yay! */
748 out[rep] = item;
749 left--;
750 break;
751 }
752 }
753 }
754 for (rep = outpos; rep < endpos; rep++) {
755 if (out[rep] == CRUSH_ITEM_UNDEF) {
756 out[rep] = CRUSH_ITEM_NONE;
757 }
758 if (out2 && out2[rep] == CRUSH_ITEM_UNDEF) {
759 out2[rep] = CRUSH_ITEM_NONE;
760 }
761 }
762 #ifndef __KERNEL__
763 if (map->choose_tries && ftotal <= map->choose_total_tries)
764 map->choose_tries[ftotal]++;
765 #endif
766 #ifdef DEBUG_INDEP
767 if (out2) {
768 dprintk("%u %d a: ", ftotal, left);
769 for (rep = outpos; rep < endpos; rep++) {
770 dprintk(" %d", out[rep]);
771 }
772 dprintk("\n");
773 dprintk("%u %d b: ", ftotal, left);
774 for (rep = outpos; rep < endpos; rep++) {
775 dprintk(" %d", out2[rep]);
776 }
777 dprintk("\n");
778 }
779 #endif
780 }
781
782 /**
783 * crush_do_rule - calculate a mapping with the given input and rule
784 * @map: the crush_map
785 * @ruleno: the rule id
786 * @x: hash input
787 * @result: pointer to result vector
788 * @result_max: maximum result size
789 * @weight: weight vector (for map leaves)
790 * @weight_max: size of weight vector
791 * @scratch: scratch vector for private use; must be >= 3 * result_max
792 */
crush_do_rule(const struct crush_map * map,int ruleno,int x,int * result,int result_max,const __u32 * weight,int weight_max,int * scratch)793 int crush_do_rule(const struct crush_map *map,
794 int ruleno, int x, int *result, int result_max,
795 const __u32 *weight, int weight_max,
796 int *scratch)
797 {
798 int result_len;
799 int *a = scratch;
800 int *b = scratch + result_max;
801 int *c = scratch + result_max*2;
802 int recurse_to_leaf;
803 int *w;
804 int wsize = 0;
805 int *o;
806 int osize;
807 int *tmp;
808 struct crush_rule *rule;
809 __u32 step;
810 int i, j;
811 int numrep;
812 int out_size;
813 /*
814 * the original choose_total_tries value was off by one (it
815 * counted "retries" and not "tries"). add one.
816 */
817 int choose_tries = map->choose_total_tries + 1;
818 int choose_leaf_tries = 0;
819 /*
820 * the local tries values were counted as "retries", though,
821 * and need no adjustment
822 */
823 int choose_local_retries = map->choose_local_tries;
824 int choose_local_fallback_retries = map->choose_local_fallback_tries;
825
826 int vary_r = map->chooseleaf_vary_r;
827 int stable = map->chooseleaf_stable;
828
829 if ((__u32)ruleno >= map->max_rules) {
830 dprintk(" bad ruleno %d\n", ruleno);
831 return 0;
832 }
833
834 rule = map->rules[ruleno];
835 result_len = 0;
836 w = a;
837 o = b;
838
839 for (step = 0; step < rule->len; step++) {
840 int firstn = 0;
841 struct crush_rule_step *curstep = &rule->steps[step];
842
843 switch (curstep->op) {
844 case CRUSH_RULE_TAKE:
845 if ((curstep->arg1 >= 0 &&
846 curstep->arg1 < map->max_devices) ||
847 (-1-curstep->arg1 >= 0 &&
848 -1-curstep->arg1 < map->max_buckets &&
849 map->buckets[-1-curstep->arg1])) {
850 w[0] = curstep->arg1;
851 wsize = 1;
852 } else {
853 dprintk(" bad take value %d\n", curstep->arg1);
854 }
855 break;
856
857 case CRUSH_RULE_SET_CHOOSE_TRIES:
858 if (curstep->arg1 > 0)
859 choose_tries = curstep->arg1;
860 break;
861
862 case CRUSH_RULE_SET_CHOOSELEAF_TRIES:
863 if (curstep->arg1 > 0)
864 choose_leaf_tries = curstep->arg1;
865 break;
866
867 case CRUSH_RULE_SET_CHOOSE_LOCAL_TRIES:
868 if (curstep->arg1 >= 0)
869 choose_local_retries = curstep->arg1;
870 break;
871
872 case CRUSH_RULE_SET_CHOOSE_LOCAL_FALLBACK_TRIES:
873 if (curstep->arg1 >= 0)
874 choose_local_fallback_retries = curstep->arg1;
875 break;
876
877 case CRUSH_RULE_SET_CHOOSELEAF_VARY_R:
878 if (curstep->arg1 >= 0)
879 vary_r = curstep->arg1;
880 break;
881
882 case CRUSH_RULE_SET_CHOOSELEAF_STABLE:
883 if (curstep->arg1 >= 0)
884 stable = curstep->arg1;
885 break;
886
887 case CRUSH_RULE_CHOOSELEAF_FIRSTN:
888 case CRUSH_RULE_CHOOSE_FIRSTN:
889 firstn = 1;
890 /* fall through */
891 case CRUSH_RULE_CHOOSELEAF_INDEP:
892 case CRUSH_RULE_CHOOSE_INDEP:
893 if (wsize == 0)
894 break;
895
896 recurse_to_leaf =
897 curstep->op ==
898 CRUSH_RULE_CHOOSELEAF_FIRSTN ||
899 curstep->op ==
900 CRUSH_RULE_CHOOSELEAF_INDEP;
901
902 /* reset output */
903 osize = 0;
904
905 for (i = 0; i < wsize; i++) {
906 int bno;
907 /*
908 * see CRUSH_N, CRUSH_N_MINUS macros.
909 * basically, numrep <= 0 means relative to
910 * the provided result_max
911 */
912 numrep = curstep->arg1;
913 if (numrep <= 0) {
914 numrep += result_max;
915 if (numrep <= 0)
916 continue;
917 }
918 j = 0;
919 /* make sure bucket id is valid */
920 bno = -1 - w[i];
921 if (bno < 0 || bno >= map->max_buckets) {
922 /* w[i] is probably CRUSH_ITEM_NONE */
923 dprintk(" bad w[i] %d\n", w[i]);
924 continue;
925 }
926 if (firstn) {
927 int recurse_tries;
928 if (choose_leaf_tries)
929 recurse_tries =
930 choose_leaf_tries;
931 else if (map->chooseleaf_descend_once)
932 recurse_tries = 1;
933 else
934 recurse_tries = choose_tries;
935 osize += crush_choose_firstn(
936 map,
937 map->buckets[bno],
938 weight, weight_max,
939 x, numrep,
940 curstep->arg2,
941 o+osize, j,
942 result_max-osize,
943 choose_tries,
944 recurse_tries,
945 choose_local_retries,
946 choose_local_fallback_retries,
947 recurse_to_leaf,
948 vary_r,
949 stable,
950 c+osize,
951 0);
952 } else {
953 out_size = ((numrep < (result_max-osize)) ?
954 numrep : (result_max-osize));
955 crush_choose_indep(
956 map,
957 map->buckets[bno],
958 weight, weight_max,
959 x, out_size, numrep,
960 curstep->arg2,
961 o+osize, j,
962 choose_tries,
963 choose_leaf_tries ?
964 choose_leaf_tries : 1,
965 recurse_to_leaf,
966 c+osize,
967 0);
968 osize += out_size;
969 }
970 }
971
972 if (recurse_to_leaf)
973 /* copy final _leaf_ values to output set */
974 memcpy(o, c, osize*sizeof(*o));
975
976 /* swap o and w arrays */
977 tmp = o;
978 o = w;
979 w = tmp;
980 wsize = osize;
981 break;
982
983
984 case CRUSH_RULE_EMIT:
985 for (i = 0; i < wsize && result_len < result_max; i++) {
986 result[result_len] = w[i];
987 result_len++;
988 }
989 wsize = 0;
990 break;
991
992 default:
993 dprintk(" unknown op %d at step %d\n",
994 curstep->op, step);
995 break;
996 }
997 }
998 return result_len;
999 }
1000