libceph: fix pg_temp updates
[sfrench/cifs-2.6.git] / net / ceph / crush / mapper.c
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
24 /*
25  * Implement the core CRUSH mapping algorithm.
26  */
27
28 /**
29  * crush_find_rule - find a crush_rule id for a given ruleset, type, and size.
30  * @map: the crush_map
31  * @ruleset: the storage ruleset id (user defined)
32  * @type: storage ruleset type (user defined)
33  * @size: output set size
34  */
35 int crush_find_rule(const struct crush_map *map, int ruleset, int type, int size)
36 {
37         __u32 i;
38
39         for (i = 0; i < map->max_rules; i++) {
40                 if (map->rules[i] &&
41                     map->rules[i]->mask.ruleset == ruleset &&
42                     map->rules[i]->mask.type == type &&
43                     map->rules[i]->mask.min_size <= size &&
44                     map->rules[i]->mask.max_size >= size)
45                         return i;
46         }
47         return -1;
48 }
49
50
51 /*
52  * bucket choose methods
53  *
54  * For each bucket algorithm, we have a "choose" method that, given a
55  * crush input @x and replica position (usually, position in output set) @r,
56  * will produce an item in the bucket.
57  */
58
59 /*
60  * Choose based on a random permutation of the bucket.
61  *
62  * We used to use some prime number arithmetic to do this, but it
63  * wasn't very random, and had some other bad behaviors.  Instead, we
64  * calculate an actual random permutation of the bucket members.
65  * Since this is expensive, we optimize for the r=0 case, which
66  * captures the vast majority of calls.
67  */
68 static int bucket_perm_choose(struct crush_bucket *bucket,
69                               int x, int r)
70 {
71         unsigned pr = r % bucket->size;
72         unsigned i, s;
73
74         /* start a new permutation if @x has changed */
75         if (bucket->perm_x != (__u32)x || bucket->perm_n == 0) {
76                 dprintk("bucket %d new x=%d\n", bucket->id, x);
77                 bucket->perm_x = x;
78
79                 /* optimize common r=0 case */
80                 if (pr == 0) {
81                         s = crush_hash32_3(bucket->hash, x, bucket->id, 0) %
82                                 bucket->size;
83                         bucket->perm[0] = s;
84                         bucket->perm_n = 0xffff;   /* magic value, see below */
85                         goto out;
86                 }
87
88                 for (i = 0; i < bucket->size; i++)
89                         bucket->perm[i] = i;
90                 bucket->perm_n = 0;
91         } else if (bucket->perm_n == 0xffff) {
92                 /* clean up after the r=0 case above */
93                 for (i = 1; i < bucket->size; i++)
94                         bucket->perm[i] = i;
95                 bucket->perm[bucket->perm[0]] = 0;
96                 bucket->perm_n = 1;
97         }
98
99         /* calculate permutation up to pr */
100         for (i = 0; i < bucket->perm_n; i++)
101                 dprintk(" perm_choose have %d: %d\n", i, bucket->perm[i]);
102         while (bucket->perm_n <= pr) {
103                 unsigned p = bucket->perm_n;
104                 /* no point in swapping the final entry */
105                 if (p < bucket->size - 1) {
106                         i = crush_hash32_3(bucket->hash, x, bucket->id, p) %
107                                 (bucket->size - p);
108                         if (i) {
109                                 unsigned t = bucket->perm[p + i];
110                                 bucket->perm[p + i] = bucket->perm[p];
111                                 bucket->perm[p] = t;
112                         }
113                         dprintk(" perm_choose swap %d with %d\n", p, p+i);
114                 }
115                 bucket->perm_n++;
116         }
117         for (i = 0; i < bucket->size; i++)
118                 dprintk(" perm_choose  %d: %d\n", i, bucket->perm[i]);
119
120         s = bucket->perm[pr];
121 out:
122         dprintk(" perm_choose %d sz=%d x=%d r=%d (%d) s=%d\n", bucket->id,
123                 bucket->size, x, r, pr, s);
124         return bucket->items[s];
125 }
126
127 /* uniform */
128 static int bucket_uniform_choose(struct crush_bucket_uniform *bucket,
129                                  int x, int r)
130 {
131         return bucket_perm_choose(&bucket->h, x, r);
132 }
133
134 /* list */
135 static int bucket_list_choose(struct crush_bucket_list *bucket,
136                               int x, int r)
137 {
138         int i;
139
140         for (i = bucket->h.size-1; i >= 0; i--) {
141                 __u64 w = crush_hash32_4(bucket->h.hash,x, bucket->h.items[i],
142                                          r, bucket->h.id);
143                 w &= 0xffff;
144                 dprintk("list_choose i=%d x=%d r=%d item %d weight %x "
145                         "sw %x rand %llx",
146                         i, x, r, bucket->h.items[i], bucket->item_weights[i],
147                         bucket->sum_weights[i], w);
148                 w *= bucket->sum_weights[i];
149                 w = w >> 16;
150                 /*dprintk(" scaled %llx\n", w);*/
151                 if (w < bucket->item_weights[i])
152                         return bucket->h.items[i];
153         }
154
155         dprintk("bad list sums for bucket %d\n", bucket->h.id);
156         return bucket->h.items[0];
157 }
158
159
160 /* (binary) tree */
161 static int height(int n)
162 {
163         int h = 0;
164         while ((n & 1) == 0) {
165                 h++;
166                 n = n >> 1;
167         }
168         return h;
169 }
170
171 static int left(int x)
172 {
173         int h = height(x);
174         return x - (1 << (h-1));
175 }
176
177 static int right(int x)
178 {
179         int h = height(x);
180         return x + (1 << (h-1));
181 }
182
183 static int terminal(int x)
184 {
185         return x & 1;
186 }
187
188 static int bucket_tree_choose(struct crush_bucket_tree *bucket,
189                               int x, int r)
190 {
191         int n, l;
192         __u32 w;
193         __u64 t;
194
195         /* start at root */
196         n = bucket->num_nodes >> 1;
197
198         while (!terminal(n)) {
199                 /* pick point in [0, w) */
200                 w = bucket->node_weights[n];
201                 t = (__u64)crush_hash32_4(bucket->h.hash, x, n, r,
202                                           bucket->h.id) * (__u64)w;
203                 t = t >> 32;
204
205                 /* descend to the left or right? */
206                 l = left(n);
207                 if (t < bucket->node_weights[l])
208                         n = l;
209                 else
210                         n = right(n);
211         }
212
213         return bucket->h.items[n >> 1];
214 }
215
216
217 /* straw */
218
219 static int bucket_straw_choose(struct crush_bucket_straw *bucket,
220                                int x, int r)
221 {
222         __u32 i;
223         int high = 0;
224         __u64 high_draw = 0;
225         __u64 draw;
226
227         for (i = 0; i < bucket->h.size; i++) {
228                 draw = crush_hash32_3(bucket->h.hash, x, bucket->h.items[i], r);
229                 draw &= 0xffff;
230                 draw *= bucket->straws[i];
231                 if (i == 0 || draw > high_draw) {
232                         high = i;
233                         high_draw = draw;
234                 }
235         }
236         return bucket->h.items[high];
237 }
238
239 static int crush_bucket_choose(struct crush_bucket *in, int x, int r)
240 {
241         dprintk(" crush_bucket_choose %d x=%d r=%d\n", in->id, x, r);
242         BUG_ON(in->size == 0);
243         switch (in->alg) {
244         case CRUSH_BUCKET_UNIFORM:
245                 return bucket_uniform_choose((struct crush_bucket_uniform *)in,
246                                           x, r);
247         case CRUSH_BUCKET_LIST:
248                 return bucket_list_choose((struct crush_bucket_list *)in,
249                                           x, r);
250         case CRUSH_BUCKET_TREE:
251                 return bucket_tree_choose((struct crush_bucket_tree *)in,
252                                           x, r);
253         case CRUSH_BUCKET_STRAW:
254                 return bucket_straw_choose((struct crush_bucket_straw *)in,
255                                            x, r);
256         default:
257                 dprintk("unknown bucket %d alg %d\n", in->id, in->alg);
258                 return in->items[0];
259         }
260 }
261
262 /*
263  * true if device is marked "out" (failed, fully offloaded)
264  * of the cluster
265  */
266 static int is_out(const struct crush_map *map, const __u32 *weight, int item, int x)
267 {
268         if (weight[item] >= 0x10000)
269                 return 0;
270         if (weight[item] == 0)
271                 return 1;
272         if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff)
273             < weight[item])
274                 return 0;
275         return 1;
276 }
277
278 /**
279  * crush_choose - choose numrep distinct items of given type
280  * @map: the crush_map
281  * @bucket: the bucket we are choose an item from
282  * @x: crush input value
283  * @numrep: the number of items to choose
284  * @type: the type of item to choose
285  * @out: pointer to output vector
286  * @outpos: our position in that vector
287  * @firstn: true if choosing "first n" items, false if choosing "indep"
288  * @recurse_to_leaf: true if we want one device under each item of given type
289  * @out2: second output vector for leaf items (if @recurse_to_leaf)
290  */
291 static int crush_choose(const struct crush_map *map,
292                         struct crush_bucket *bucket,
293                         const __u32 *weight,
294                         int x, int numrep, int type,
295                         int *out, int outpos,
296                         int firstn, int recurse_to_leaf,
297                         int *out2)
298 {
299         int rep;
300         unsigned int ftotal, flocal;
301         int retry_descent, retry_bucket, skip_rep;
302         struct crush_bucket *in = bucket;
303         int r;
304         int i;
305         int item = 0;
306         int itemtype;
307         int collide, reject;
308         const unsigned int orig_tries = 5; /* attempts before we fall back to search */
309
310         dprintk("CHOOSE%s bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "",
311                 bucket->id, x, outpos, numrep);
312
313         for (rep = outpos; rep < numrep; rep++) {
314                 /* keep trying until we get a non-out, non-colliding item */
315                 ftotal = 0;
316                 skip_rep = 0;
317                 do {
318                         retry_descent = 0;
319                         in = bucket;               /* initial bucket */
320
321                         /* choose through intervening buckets */
322                         flocal = 0;
323                         do {
324                                 collide = 0;
325                                 retry_bucket = 0;
326                                 r = rep;
327                                 if (in->alg == CRUSH_BUCKET_UNIFORM) {
328                                         /* be careful */
329                                         if (firstn || (__u32)numrep >= in->size)
330                                                 /* r' = r + f_total */
331                                                 r += ftotal;
332                                         else if (in->size % numrep == 0)
333                                                 /* r'=r+(n+1)*f_local */
334                                                 r += (numrep+1) *
335                                                         (flocal+ftotal);
336                                         else
337                                                 /* r' = r + n*f_local */
338                                                 r += numrep * (flocal+ftotal);
339                                 } else {
340                                         if (firstn)
341                                                 /* r' = r + f_total */
342                                                 r += ftotal;
343                                         else
344                                                 /* r' = r + n*f_local */
345                                                 r += numrep * (flocal+ftotal);
346                                 }
347
348                                 /* bucket choose */
349                                 if (in->size == 0) {
350                                         reject = 1;
351                                         goto reject;
352                                 }
353                                 if (flocal >= (in->size>>1) &&
354                                     flocal > orig_tries)
355                                         item = bucket_perm_choose(in, x, r);
356                                 else
357                                         item = crush_bucket_choose(in, x, r);
358                                 if (item >= map->max_devices) {
359                                         dprintk("   bad item %d\n", item);
360                                         skip_rep = 1;
361                                         break;
362                                 }
363
364                                 /* desired type? */
365                                 if (item < 0)
366                                         itemtype = map->buckets[-1-item]->type;
367                                 else
368                                         itemtype = 0;
369                                 dprintk("  item %d type %d\n", item, itemtype);
370
371                                 /* keep going? */
372                                 if (itemtype != type) {
373                                         if (item >= 0 ||
374                                             (-1-item) >= map->max_buckets) {
375                                                 dprintk("   bad item type %d\n", type);
376                                                 skip_rep = 1;
377                                                 break;
378                                         }
379                                         in = map->buckets[-1-item];
380                                         retry_bucket = 1;
381                                         continue;
382                                 }
383
384                                 /* collision? */
385                                 for (i = 0; i < outpos; i++) {
386                                         if (out[i] == item) {
387                                                 collide = 1;
388                                                 break;
389                                         }
390                                 }
391
392                                 reject = 0;
393                                 if (recurse_to_leaf) {
394                                         if (item < 0) {
395                                                 if (crush_choose(map,
396                                                          map->buckets[-1-item],
397                                                          weight,
398                                                          x, outpos+1, 0,
399                                                          out2, outpos,
400                                                          firstn, 0,
401                                                          NULL) <= outpos)
402                                                         /* didn't get leaf */
403                                                         reject = 1;
404                                         } else {
405                                                 /* we already have a leaf! */
406                                                 out2[outpos] = item;
407                                         }
408                                 }
409
410                                 if (!reject) {
411                                         /* out? */
412                                         if (itemtype == 0)
413                                                 reject = is_out(map, weight,
414                                                                 item, x);
415                                         else
416                                                 reject = 0;
417                                 }
418
419 reject:
420                                 if (reject || collide) {
421                                         ftotal++;
422                                         flocal++;
423
424                                         if (collide && flocal < 3)
425                                                 /* retry locally a few times */
426                                                 retry_bucket = 1;
427                                         else if (flocal <= in->size + orig_tries)
428                                                 /* exhaustive bucket search */
429                                                 retry_bucket = 1;
430                                         else if (ftotal < 20)
431                                                 /* then retry descent */
432                                                 retry_descent = 1;
433                                         else
434                                                 /* else give up */
435                                                 skip_rep = 1;
436                                         dprintk("  reject %d  collide %d  "
437                                                 "ftotal %u  flocal %u\n",
438                                                 reject, collide, ftotal,
439                                                 flocal);
440                                 }
441                         } while (retry_bucket);
442                 } while (retry_descent);
443
444                 if (skip_rep) {
445                         dprintk("skip rep\n");
446                         continue;
447                 }
448
449                 dprintk("CHOOSE got %d\n", item);
450                 out[outpos] = item;
451                 outpos++;
452         }
453
454         dprintk("CHOOSE returns %d\n", outpos);
455         return outpos;
456 }
457
458
459 /**
460  * crush_do_rule - calculate a mapping with the given input and rule
461  * @map: the crush_map
462  * @ruleno: the rule id
463  * @x: hash input
464  * @result: pointer to result vector
465  * @result_max: maximum result size
466  */
467 int crush_do_rule(const struct crush_map *map,
468                   int ruleno, int x, int *result, int result_max,
469                   const __u32 *weight)
470 {
471         int result_len;
472         int a[CRUSH_MAX_SET];
473         int b[CRUSH_MAX_SET];
474         int c[CRUSH_MAX_SET];
475         int recurse_to_leaf;
476         int *w;
477         int wsize = 0;
478         int *o;
479         int osize;
480         int *tmp;
481         struct crush_rule *rule;
482         __u32 step;
483         int i, j;
484         int numrep;
485         int firstn;
486
487         if ((__u32)ruleno >= map->max_rules) {
488                 dprintk(" bad ruleno %d\n", ruleno);
489                 return 0;
490         }
491
492         rule = map->rules[ruleno];
493         result_len = 0;
494         w = a;
495         o = b;
496
497         for (step = 0; step < rule->len; step++) {
498                 struct crush_rule_step *curstep = &rule->steps[step];
499
500                 firstn = 0;
501                 switch (curstep->op) {
502                 case CRUSH_RULE_TAKE:
503                         w[0] = curstep->arg1;
504                         wsize = 1;
505                         break;
506
507                 case CRUSH_RULE_CHOOSE_LEAF_FIRSTN:
508                 case CRUSH_RULE_CHOOSE_FIRSTN:
509                         firstn = 1;
510                         /* fall through */
511                 case CRUSH_RULE_CHOOSE_LEAF_INDEP:
512                 case CRUSH_RULE_CHOOSE_INDEP:
513                         if (wsize == 0)
514                                 break;
515
516                         recurse_to_leaf =
517                                 curstep->op ==
518                                  CRUSH_RULE_CHOOSE_LEAF_FIRSTN ||
519                                 curstep->op ==
520                                 CRUSH_RULE_CHOOSE_LEAF_INDEP;
521
522                         /* reset output */
523                         osize = 0;
524
525                         for (i = 0; i < wsize; i++) {
526                                 /*
527                                  * see CRUSH_N, CRUSH_N_MINUS macros.
528                                  * basically, numrep <= 0 means relative to
529                                  * the provided result_max
530                                  */
531                                 numrep = curstep->arg1;
532                                 if (numrep <= 0) {
533                                         numrep += result_max;
534                                         if (numrep <= 0)
535                                                 continue;
536                                 }
537                                 j = 0;
538                                 osize += crush_choose(map,
539                                                       map->buckets[-1-w[i]],
540                                                       weight,
541                                                       x, numrep,
542                                                       curstep->arg2,
543                                                       o+osize, j,
544                                                       firstn,
545                                                       recurse_to_leaf, c+osize);
546                         }
547
548                         if (recurse_to_leaf)
549                                 /* copy final _leaf_ values to output set */
550                                 memcpy(o, c, osize*sizeof(*o));
551
552                         /* swap t and w arrays */
553                         tmp = o;
554                         o = w;
555                         w = tmp;
556                         wsize = osize;
557                         break;
558
559
560                 case CRUSH_RULE_EMIT:
561                         for (i = 0; i < wsize && result_len < result_max; i++) {
562                                 result[result_len] = w[i];
563                                 result_len++;
564                         }
565                         wsize = 0;
566                         break;
567
568                 default:
569                         dprintk(" unknown op %d at step %d\n",
570                                 curstep->op, step);
571                         break;
572                 }
573         }
574         return result_len;
575 }
576
577