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] : NULL),
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] : NULL),
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 }