1
2 #ifdef __KERNEL__
3 # include <linux/string.h>
4 # include <linux/slab.h>
5 # include <linux/bug.h>
6 # include <linux/kernel.h>
7 # ifndef dprintk
8 # define dprintk(args...)
9 # endif
10 #else
11 # include <string.h>
12 # include <stdio.h>
13 # include <stdlib.h>
14 # include <assert.h>
15 # define BUG_ON(x) assert(!(x))
16 # define dprintk(args...) /* printf(args) */
17 # define kmalloc(x, f) malloc(x)
18 # define kfree(x) free(x)
19 #endif
20
21 #include <linux/crush/crush.h>
22 #include <linux/crush/hash.h>
23 #include <linux/crush/mapper.h>
24
25 /*
26 * Implement the core CRUSH mapping algorithm.
27 */
28
29 /**
30 * crush_find_rule - find a crush_rule id for a given ruleset, type, and size.
31 * @map: the crush_map
32 * @ruleset: the storage ruleset id (user defined)
33 * @type: storage ruleset type (user defined)
34 * @size: output set size
35 */
crush_find_rule(const struct crush_map * map,int ruleset,int type,int size)36 int crush_find_rule(const struct crush_map *map, int ruleset, int type, int size)
37 {
38 __u32 i;
39
40 for (i = 0; i < map->max_rules; i++) {
41 if (map->rules[i] &&
42 map->rules[i]->mask.ruleset == ruleset &&
43 map->rules[i]->mask.type == type &&
44 map->rules[i]->mask.min_size <= size &&
45 map->rules[i]->mask.max_size >= size)
46 return i;
47 }
48 return -1;
49 }
50
51
52 /*
53 * bucket choose methods
54 *
55 * For each bucket algorithm, we have a "choose" method that, given a
56 * crush input @x and replica position (usually, position in output set) @r,
57 * will produce an item in the bucket.
58 */
59
60 /*
61 * Choose based on a random permutation of the bucket.
62 *
63 * We used to use some prime number arithmetic to do this, but it
64 * wasn't very random, and had some other bad behaviors. Instead, we
65 * calculate an actual random permutation of the bucket members.
66 * Since this is expensive, we optimize for the r=0 case, which
67 * captures the vast majority of calls.
68 */
bucket_perm_choose(struct crush_bucket * bucket,int x,int r)69 static int bucket_perm_choose(struct crush_bucket *bucket,
70 int x, int r)
71 {
72 unsigned int pr = r % bucket->size;
73 unsigned int i, s;
74
75 /* start a new permutation if @x has changed */
76 if (bucket->perm_x != (__u32)x || bucket->perm_n == 0) {
77 dprintk("bucket %d new x=%d\n", bucket->id, x);
78 bucket->perm_x = x;
79
80 /* optimize common r=0 case */
81 if (pr == 0) {
82 s = crush_hash32_3(bucket->hash, x, bucket->id, 0) %
83 bucket->size;
84 bucket->perm[0] = s;
85 bucket->perm_n = 0xffff; /* magic value, see below */
86 goto out;
87 }
88
89 for (i = 0; i < bucket->size; i++)
90 bucket->perm[i] = i;
91 bucket->perm_n = 0;
92 } else if (bucket->perm_n == 0xffff) {
93 /* clean up after the r=0 case above */
94 for (i = 1; i < bucket->size; i++)
95 bucket->perm[i] = i;
96 bucket->perm[bucket->perm[0]] = 0;
97 bucket->perm_n = 1;
98 }
99
100 /* calculate permutation up to pr */
101 for (i = 0; i < bucket->perm_n; i++)
102 dprintk(" perm_choose have %d: %d\n", i, bucket->perm[i]);
103 while (bucket->perm_n <= pr) {
104 unsigned int p = bucket->perm_n;
105 /* no point in swapping the final entry */
106 if (p < bucket->size - 1) {
107 i = crush_hash32_3(bucket->hash, x, bucket->id, p) %
108 (bucket->size - p);
109 if (i) {
110 unsigned int t = bucket->perm[p + i];
111 bucket->perm[p + i] = bucket->perm[p];
112 bucket->perm[p] = t;
113 }
114 dprintk(" perm_choose swap %d with %d\n", p, p+i);
115 }
116 bucket->perm_n++;
117 }
118 for (i = 0; i < bucket->size; i++)
119 dprintk(" perm_choose %d: %d\n", i, bucket->perm[i]);
120
121 s = bucket->perm[pr];
122 out:
123 dprintk(" perm_choose %d sz=%d x=%d r=%d (%d) s=%d\n", bucket->id,
124 bucket->size, x, r, pr, s);
125 return bucket->items[s];
126 }
127
128 /* uniform */
bucket_uniform_choose(struct crush_bucket_uniform * bucket,int x,int r)129 static int bucket_uniform_choose(struct crush_bucket_uniform *bucket,
130 int x, int r)
131 {
132 return bucket_perm_choose(&bucket->h, x, r);
133 }
134
135 /* list */
bucket_list_choose(struct crush_bucket_list * bucket,int x,int r)136 static int bucket_list_choose(struct crush_bucket_list *bucket,
137 int x, int r)
138 {
139 int i;
140
141 for (i = bucket->h.size-1; i >= 0; i--) {
142 __u64 w = crush_hash32_4(bucket->h.hash,x, bucket->h.items[i],
143 r, bucket->h.id);
144 w &= 0xffff;
145 dprintk("list_choose i=%d x=%d r=%d item %d weight %x "
146 "sw %x rand %llx",
147 i, x, r, bucket->h.items[i], bucket->item_weights[i],
148 bucket->sum_weights[i], w);
149 w *= bucket->sum_weights[i];
150 w = w >> 16;
151 /*dprintk(" scaled %llx\n", w);*/
152 if (w < bucket->item_weights[i])
153 return bucket->h.items[i];
154 }
155
156 dprintk("bad list sums for bucket %d\n", bucket->h.id);
157 return bucket->h.items[0];
158 }
159
160
161 /* (binary) tree */
height(int n)162 static int height(int n)
163 {
164 int h = 0;
165 while ((n & 1) == 0) {
166 h++;
167 n = n >> 1;
168 }
169 return h;
170 }
171
left(int x)172 static int left(int x)
173 {
174 int h = height(x);
175 return x - (1 << (h-1));
176 }
177
right(int x)178 static int right(int x)
179 {
180 int h = height(x);
181 return x + (1 << (h-1));
182 }
183
terminal(int x)184 static int terminal(int x)
185 {
186 return x & 1;
187 }
188
bucket_tree_choose(struct crush_bucket_tree * bucket,int x,int r)189 static int bucket_tree_choose(struct crush_bucket_tree *bucket,
190 int x, int r)
191 {
192 int n, l;
193 __u32 w;
194 __u64 t;
195
196 /* start at root */
197 n = bucket->num_nodes >> 1;
198
199 while (!terminal(n)) {
200 /* pick point in [0, w) */
201 w = bucket->node_weights[n];
202 t = (__u64)crush_hash32_4(bucket->h.hash, x, n, r,
203 bucket->h.id) * (__u64)w;
204 t = t >> 32;
205
206 /* descend to the left or right? */
207 l = left(n);
208 if (t < bucket->node_weights[l])
209 n = l;
210 else
211 n = right(n);
212 }
213
214 return bucket->h.items[n >> 1];
215 }
216
217
218 /* straw */
219
bucket_straw_choose(struct crush_bucket_straw * bucket,int x,int r)220 static int bucket_straw_choose(struct crush_bucket_straw *bucket,
221 int x, int r)
222 {
223 __u32 i;
224 int high = 0;
225 __u64 high_draw = 0;
226 __u64 draw;
227
228 for (i = 0; i < bucket->h.size; i++) {
229 draw = crush_hash32_3(bucket->h.hash, x, bucket->h.items[i], r);
230 draw &= 0xffff;
231 draw *= bucket->straws[i];
232 if (i == 0 || draw > high_draw) {
233 high = i;
234 high_draw = draw;
235 }
236 }
237 return bucket->h.items[high];
238 }
239
crush_bucket_choose(struct crush_bucket * in,int x,int r)240 static int crush_bucket_choose(struct crush_bucket *in, int x, int r)
241 {
242 dprintk(" crush_bucket_choose %d x=%d r=%d\n", in->id, x, r);
243 BUG_ON(in->size == 0);
244 switch (in->alg) {
245 case CRUSH_BUCKET_UNIFORM:
246 return bucket_uniform_choose((struct crush_bucket_uniform *)in,
247 x, r);
248 case CRUSH_BUCKET_LIST:
249 return bucket_list_choose((struct crush_bucket_list *)in,
250 x, r);
251 case CRUSH_BUCKET_TREE:
252 return bucket_tree_choose((struct crush_bucket_tree *)in,
253 x, r);
254 case CRUSH_BUCKET_STRAW:
255 return bucket_straw_choose((struct crush_bucket_straw *)in,
256 x, r);
257 default:
258 dprintk("unknown bucket %d alg %d\n", in->id, in->alg);
259 return in->items[0];
260 }
261 }
262
263 /*
264 * true if device is marked "out" (failed, fully offloaded)
265 * of the cluster
266 */
is_out(const struct crush_map * map,const __u32 * weight,int item,int x)267 static int is_out(const struct crush_map *map, const __u32 *weight, int item, int x)
268 {
269 if (weight[item] >= 0x10000)
270 return 0;
271 if (weight[item] == 0)
272 return 1;
273 if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff)
274 < weight[item])
275 return 0;
276 return 1;
277 }
278
279 /**
280 * crush_choose - choose numrep distinct items of given type
281 * @map: the crush_map
282 * @bucket: the bucket we are choose an item from
283 * @x: crush input value
284 * @numrep: the number of items to choose
285 * @type: the type of item to choose
286 * @out: pointer to output vector
287 * @outpos: our position in that vector
288 * @firstn: true if choosing "first n" items, false if choosing "indep"
289 * @recurse_to_leaf: true if we want one device under each item of given type
290 * @descend_once: true if we should only try one descent before giving up
291 * @out2: second output vector for leaf items (if @recurse_to_leaf)
292 */
crush_choose(const struct crush_map * map,struct crush_bucket * bucket,const __u32 * weight,int x,int numrep,int type,int * out,int outpos,int firstn,int recurse_to_leaf,int descend_once,int * out2)293 static int crush_choose(const struct crush_map *map,
294 struct crush_bucket *bucket,
295 const __u32 *weight,
296 int x, int numrep, int type,
297 int *out, int outpos,
298 int firstn, int recurse_to_leaf,
299 int descend_once, int *out2)
300 {
301 int rep;
302 unsigned int ftotal, flocal;
303 int retry_descent, retry_bucket, skip_rep;
304 struct crush_bucket *in = bucket;
305 int r;
306 int i;
307 int item = 0;
308 int itemtype;
309 int collide, reject;
310
311 dprintk("CHOOSE%s bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "",
312 bucket->id, x, outpos, numrep);
313
314 for (rep = outpos; rep < numrep; rep++) {
315 /* keep trying until we get a non-out, non-colliding item */
316 ftotal = 0;
317 skip_rep = 0;
318 do {
319 retry_descent = 0;
320 in = bucket; /* initial bucket */
321
322 /* choose through intervening buckets */
323 flocal = 0;
324 do {
325 collide = 0;
326 retry_bucket = 0;
327 r = rep;
328 if (in->alg == CRUSH_BUCKET_UNIFORM) {
329 /* be careful */
330 if (firstn || (__u32)numrep >= in->size)
331 /* r' = r + f_total */
332 r += ftotal;
333 else if (in->size % numrep == 0)
334 /* r'=r+(n+1)*f_local */
335 r += (numrep+1) *
336 (flocal+ftotal);
337 else
338 /* r' = r + n*f_local */
339 r += numrep * (flocal+ftotal);
340 } else {
341 if (firstn)
342 /* r' = r + f_total */
343 r += ftotal;
344 else
345 /* r' = r + n*f_local */
346 r += numrep * (flocal+ftotal);
347 }
348
349 /* bucket choose */
350 if (in->size == 0) {
351 reject = 1;
352 goto reject;
353 }
354 if (map->choose_local_fallback_tries > 0 &&
355 flocal >= (in->size>>1) &&
356 flocal > map->choose_local_fallback_tries)
357 item = bucket_perm_choose(in, x, r);
358 else
359 item = crush_bucket_choose(in, x, r);
360 if (item >= map->max_devices) {
361 dprintk(" bad item %d\n", item);
362 skip_rep = 1;
363 break;
364 }
365
366 /* desired type? */
367 if (item < 0)
368 itemtype = map->buckets[-1-item]->type;
369 else
370 itemtype = 0;
371 dprintk(" item %d type %d\n", item, itemtype);
372
373 /* keep going? */
374 if (itemtype != type) {
375 if (item >= 0 ||
376 (-1-item) >= map->max_buckets) {
377 dprintk(" bad item type %d\n", type);
378 skip_rep = 1;
379 break;
380 }
381 in = map->buckets[-1-item];
382 retry_bucket = 1;
383 continue;
384 }
385
386 /* collision? */
387 for (i = 0; i < outpos; i++) {
388 if (out[i] == item) {
389 collide = 1;
390 break;
391 }
392 }
393
394 reject = 0;
395 if (!collide && recurse_to_leaf) {
396 if (item < 0) {
397 if (crush_choose(map,
398 map->buckets[-1-item],
399 weight,
400 x, outpos+1, 0,
401 out2, outpos,
402 firstn, 0,
403 map->chooseleaf_descend_once,
404 NULL) <= outpos)
405 /* didn't get leaf */
406 reject = 1;
407 } else {
408 /* we already have a leaf! */
409 out2[outpos] = item;
410 }
411 }
412
413 if (!reject) {
414 /* out? */
415 if (itemtype == 0)
416 reject = is_out(map, weight,
417 item, x);
418 else
419 reject = 0;
420 }
421
422 reject:
423 if (reject || collide) {
424 ftotal++;
425 flocal++;
426
427 if (reject && descend_once)
428 /* let outer call try again */
429 skip_rep = 1;
430 else if (collide && flocal <= map->choose_local_tries)
431 /* retry locally a few times */
432 retry_bucket = 1;
433 else if (map->choose_local_fallback_tries > 0 &&
434 flocal <= in->size + map->choose_local_fallback_tries)
435 /* exhaustive bucket search */
436 retry_bucket = 1;
437 else if (ftotal <= map->choose_total_tries)
438 /* then retry descent */
439 retry_descent = 1;
440 else
441 /* else give up */
442 skip_rep = 1;
443 dprintk(" reject %d collide %d "
444 "ftotal %u flocal %u\n",
445 reject, collide, ftotal,
446 flocal);
447 }
448 } while (retry_bucket);
449 } while (retry_descent);
450
451 if (skip_rep) {
452 dprintk("skip rep\n");
453 continue;
454 }
455
456 dprintk("CHOOSE got %d\n", item);
457 out[outpos] = item;
458 outpos++;
459 }
460
461 dprintk("CHOOSE returns %d\n", outpos);
462 return outpos;
463 }
464
465
466 /**
467 * crush_do_rule - calculate a mapping with the given input and rule
468 * @map: the crush_map
469 * @ruleno: the rule id
470 * @x: hash input
471 * @result: pointer to result vector
472 * @result_max: maximum result size
473 */
crush_do_rule(const struct crush_map * map,int ruleno,int x,int * result,int result_max,const __u32 * weight)474 int crush_do_rule(const struct crush_map *map,
475 int ruleno, int x, int *result, int result_max,
476 const __u32 *weight)
477 {
478 int result_len;
479 int a[CRUSH_MAX_SET];
480 int b[CRUSH_MAX_SET];
481 int c[CRUSH_MAX_SET];
482 int recurse_to_leaf;
483 int *w;
484 int wsize = 0;
485 int *o;
486 int osize;
487 int *tmp;
488 struct crush_rule *rule;
489 __u32 step;
490 int i, j;
491 int numrep;
492 int firstn;
493 const int descend_once = 0;
494
495 if ((__u32)ruleno >= map->max_rules) {
496 dprintk(" bad ruleno %d\n", ruleno);
497 return 0;
498 }
499
500 rule = map->rules[ruleno];
501 result_len = 0;
502 w = a;
503 o = b;
504
505 for (step = 0; step < rule->len; step++) {
506 struct crush_rule_step *curstep = &rule->steps[step];
507
508 firstn = 0;
509 switch (curstep->op) {
510 case CRUSH_RULE_TAKE:
511 w[0] = curstep->arg1;
512 wsize = 1;
513 break;
514
515 case CRUSH_RULE_CHOOSE_LEAF_FIRSTN:
516 case CRUSH_RULE_CHOOSE_FIRSTN:
517 firstn = 1;
518 /* fall through */
519 case CRUSH_RULE_CHOOSE_LEAF_INDEP:
520 case CRUSH_RULE_CHOOSE_INDEP:
521 if (wsize == 0)
522 break;
523
524 recurse_to_leaf =
525 curstep->op ==
526 CRUSH_RULE_CHOOSE_LEAF_FIRSTN ||
527 curstep->op ==
528 CRUSH_RULE_CHOOSE_LEAF_INDEP;
529
530 /* reset output */
531 osize = 0;
532
533 for (i = 0; i < wsize; i++) {
534 /*
535 * see CRUSH_N, CRUSH_N_MINUS macros.
536 * basically, numrep <= 0 means relative to
537 * the provided result_max
538 */
539 numrep = curstep->arg1;
540 if (numrep <= 0) {
541 numrep += result_max;
542 if (numrep <= 0)
543 continue;
544 }
545 j = 0;
546 osize += crush_choose(map,
547 map->buckets[-1-w[i]],
548 weight,
549 x, numrep,
550 curstep->arg2,
551 o+osize, j,
552 firstn,
553 recurse_to_leaf,
554 descend_once, c+osize);
555 }
556
557 if (recurse_to_leaf)
558 /* copy final _leaf_ values to output set */
559 memcpy(o, c, osize*sizeof(*o));
560
561 /* swap t and w arrays */
562 tmp = o;
563 o = w;
564 w = tmp;
565 wsize = osize;
566 break;
567
568
569 case CRUSH_RULE_EMIT:
570 for (i = 0; i < wsize && result_len < result_max; i++) {
571 result[result_len] = w[i];
572 result_len++;
573 }
574 wsize = 0;
575 break;
576
577 default:
578 dprintk(" unknown op %d at step %d\n",
579 curstep->op, step);
580 break;
581 }
582 }
583 return result_len;
584 }
585
586
587