ceph: fix crush device 'out' threshold to 1.0, not 0.1
[sfrench/cifs-2.6.git] / fs / 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 "crush.h"
22 #include "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(struct crush_map *map, int ruleset, int type, int size)
36 {
37         int 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 != 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         BUG_ON(1);
156         return 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         int 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         switch (in->alg) {
243         case CRUSH_BUCKET_UNIFORM:
244                 return bucket_uniform_choose((struct crush_bucket_uniform *)in,
245                                           x, r);
246         case CRUSH_BUCKET_LIST:
247                 return bucket_list_choose((struct crush_bucket_list *)in,
248                                           x, r);
249         case CRUSH_BUCKET_TREE:
250                 return bucket_tree_choose((struct crush_bucket_tree *)in,
251                                           x, r);
252         case CRUSH_BUCKET_STRAW:
253                 return bucket_straw_choose((struct crush_bucket_straw *)in,
254                                            x, r);
255         default:
256                 BUG_ON(1);
257                 return in->items[0];
258         }
259 }
260
261 /*
262  * true if device is marked "out" (failed, fully offloaded)
263  * of the cluster
264  */
265 static int is_out(struct crush_map *map, __u32 *weight, int item, int x)
266 {
267         if (weight[item] >= 0x10000)
268                 return 0;
269         if (weight[item] == 0)
270                 return 1;
271         if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff)
272             < weight[item])
273                 return 0;
274         return 1;
275 }
276
277 /**
278  * crush_choose - choose numrep distinct items of given type
279  * @map: the crush_map
280  * @bucket: the bucket we are choose an item from
281  * @x: crush input value
282  * @numrep: the number of items to choose
283  * @type: the type of item to choose
284  * @out: pointer to output vector
285  * @outpos: our position in that vector
286  * @firstn: true if choosing "first n" items, false if choosing "indep"
287  * @recurse_to_leaf: true if we want one device under each item of given type
288  * @out2: second output vector for leaf items (if @recurse_to_leaf)
289  */
290 static int crush_choose(struct crush_map *map,
291                         struct crush_bucket *bucket,
292                         __u32 *weight,
293                         int x, int numrep, int type,
294                         int *out, int outpos,
295                         int firstn, int recurse_to_leaf,
296                         int *out2)
297 {
298         int rep;
299         int ftotal, flocal;
300         int retry_descent, retry_bucket, skip_rep;
301         struct crush_bucket *in = bucket;
302         int r;
303         int i;
304         int item = 0;
305         int itemtype;
306         int collide, reject;
307         const int orig_tries = 5; /* attempts before we fall back to search */
308
309         dprintk("CHOOSE%s bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "",
310                 bucket->id, x, outpos, numrep);
311
312         for (rep = outpos; rep < numrep; rep++) {
313                 /* keep trying until we get a non-out, non-colliding item */
314                 ftotal = 0;
315                 skip_rep = 0;
316                 do {
317                         retry_descent = 0;
318                         in = bucket;               /* initial bucket */
319
320                         /* choose through intervening buckets */
321                         flocal = 0;
322                         do {
323                                 collide = 0;
324                                 retry_bucket = 0;
325                                 r = rep;
326                                 if (in->alg == CRUSH_BUCKET_UNIFORM) {
327                                         /* be careful */
328                                         if (firstn || numrep >= in->size)
329                                                 /* r' = r + f_total */
330                                                 r += ftotal;
331                                         else if (in->size % numrep == 0)
332                                                 /* r'=r+(n+1)*f_local */
333                                                 r += (numrep+1) *
334                                                         (flocal+ftotal);
335                                         else
336                                                 /* r' = r + n*f_local */
337                                                 r += numrep * (flocal+ftotal);
338                                 } else {
339                                         if (firstn)
340                                                 /* r' = r + f_total */
341                                                 r += ftotal;
342                                         else
343                                                 /* r' = r + n*f_local */
344                                                 r += numrep * (flocal+ftotal);
345                                 }
346
347                                 /* bucket choose */
348                                 if (in->size == 0) {
349                                         reject = 1;
350                                         goto reject;
351                                 }
352                                 if (flocal >= (in->size>>1) &&
353                                     flocal > orig_tries)
354                                         item = bucket_perm_choose(in, x, r);
355                                 else
356                                         item = crush_bucket_choose(in, x, r);
357                                 BUG_ON(item >= map->max_devices);
358
359                                 /* desired type? */
360                                 if (item < 0)
361                                         itemtype = map->buckets[-1-item]->type;
362                                 else
363                                         itemtype = 0;
364                                 dprintk("  item %d type %d\n", item, itemtype);
365
366                                 /* keep going? */
367                                 if (itemtype != type) {
368                                         BUG_ON(item >= 0 ||
369                                                (-1-item) >= map->max_buckets);
370                                         in = map->buckets[-1-item];
371                                         retry_bucket = 1;
372                                         continue;
373                                 }
374
375                                 /* collision? */
376                                 for (i = 0; i < outpos; i++) {
377                                         if (out[i] == item) {
378                                                 collide = 1;
379                                                 break;
380                                         }
381                                 }
382
383                                 reject = 0;
384                                 if (recurse_to_leaf) {
385                                         if (item < 0) {
386                                                 if (crush_choose(map,
387                                                          map->buckets[-1-item],
388                                                          weight,
389                                                          x, outpos+1, 0,
390                                                          out2, outpos,
391                                                          firstn, 0,
392                                                          NULL) <= outpos)
393                                                         /* didn't get leaf */
394                                                         reject = 1;
395                                         } else {
396                                                 /* we already have a leaf! */
397                                                 out2[outpos] = item;
398                                         }
399                                 }
400
401                                 if (!reject) {
402                                         /* out? */
403                                         if (itemtype == 0)
404                                                 reject = is_out(map, weight,
405                                                                 item, x);
406                                         else
407                                                 reject = 0;
408                                 }
409
410 reject:
411                                 if (reject || collide) {
412                                         ftotal++;
413                                         flocal++;
414
415                                         if (collide && flocal < 3)
416                                                 /* retry locally a few times */
417                                                 retry_bucket = 1;
418                                         else if (flocal < in->size + orig_tries)
419                                                 /* exhaustive bucket search */
420                                                 retry_bucket = 1;
421                                         else if (ftotal < 20)
422                                                 /* then retry descent */
423                                                 retry_descent = 1;
424                                         else
425                                                 /* else give up */
426                                                 skip_rep = 1;
427                                         dprintk("  reject %d  collide %d  "
428                                                 "ftotal %d  flocal %d\n",
429                                                 reject, collide, ftotal,
430                                                 flocal);
431                                 }
432                         } while (retry_bucket);
433                 } while (retry_descent);
434
435                 if (skip_rep) {
436                         dprintk("skip rep\n");
437                         continue;
438                 }
439
440                 dprintk("CHOOSE got %d\n", item);
441                 out[outpos] = item;
442                 outpos++;
443         }
444
445         dprintk("CHOOSE returns %d\n", outpos);
446         return outpos;
447 }
448
449
450 /**
451  * crush_do_rule - calculate a mapping with the given input and rule
452  * @map: the crush_map
453  * @ruleno: the rule id
454  * @x: hash input
455  * @result: pointer to result vector
456  * @result_max: maximum result size
457  * @force: force initial replica choice; -1 for none
458  */
459 int crush_do_rule(struct crush_map *map,
460                   int ruleno, int x, int *result, int result_max,
461                   int force, __u32 *weight)
462 {
463         int result_len;
464         int force_context[CRUSH_MAX_DEPTH];
465         int force_pos = -1;
466         int a[CRUSH_MAX_SET];
467         int b[CRUSH_MAX_SET];
468         int c[CRUSH_MAX_SET];
469         int recurse_to_leaf;
470         int *w;
471         int wsize = 0;
472         int *o;
473         int osize;
474         int *tmp;
475         struct crush_rule *rule;
476         int step;
477         int i, j;
478         int numrep;
479         int firstn;
480         int rc = -1;
481
482         BUG_ON(ruleno >= map->max_rules);
483
484         rule = map->rules[ruleno];
485         result_len = 0;
486         w = a;
487         o = b;
488
489         /*
490          * determine hierarchical context of force, if any.  note
491          * that this may or may not correspond to the specific types
492          * referenced by the crush rule.
493          */
494         if (force >= 0) {
495                 if (force >= map->max_devices ||
496                     map->device_parents[force] == 0) {
497                         /*dprintk("CRUSH: forcefed device dne\n");*/
498                         rc = -1;  /* force fed device dne */
499                         goto out;
500                 }
501                 if (!is_out(map, weight, force, x)) {
502                         while (1) {
503                                 force_context[++force_pos] = force;
504                                 if (force >= 0)
505                                         force = map->device_parents[force];
506                                 else
507                                         force = map->bucket_parents[-1-force];
508                                 if (force == 0)
509                                         break;
510                         }
511                 }
512         }
513
514         for (step = 0; step < rule->len; step++) {
515                 firstn = 0;
516                 switch (rule->steps[step].op) {
517                 case CRUSH_RULE_TAKE:
518                         w[0] = rule->steps[step].arg1;
519                         if (force_pos >= 0) {
520                                 BUG_ON(force_context[force_pos] != w[0]);
521                                 force_pos--;
522                         }
523                         wsize = 1;
524                         break;
525
526                 case CRUSH_RULE_CHOOSE_LEAF_FIRSTN:
527                 case CRUSH_RULE_CHOOSE_FIRSTN:
528                         firstn = 1;
529                 case CRUSH_RULE_CHOOSE_LEAF_INDEP:
530                 case CRUSH_RULE_CHOOSE_INDEP:
531                         BUG_ON(wsize == 0);
532
533                         recurse_to_leaf =
534                                 rule->steps[step].op ==
535                                  CRUSH_RULE_CHOOSE_LEAF_FIRSTN ||
536                                 rule->steps[step].op ==
537                                 CRUSH_RULE_CHOOSE_LEAF_INDEP;
538
539                         /* reset output */
540                         osize = 0;
541
542                         for (i = 0; i < wsize; i++) {
543                                 /*
544                                  * see CRUSH_N, CRUSH_N_MINUS macros.
545                                  * basically, numrep <= 0 means relative to
546                                  * the provided result_max
547                                  */
548                                 numrep = rule->steps[step].arg1;
549                                 if (numrep <= 0) {
550                                         numrep += result_max;
551                                         if (numrep <= 0)
552                                                 continue;
553                                 }
554                                 j = 0;
555                                 if (osize == 0 && force_pos >= 0) {
556                                         /* skip any intermediate types */
557                                         while (force_pos &&
558                                                force_context[force_pos] < 0 &&
559                                                rule->steps[step].arg2 !=
560                                                map->buckets[-1 -
561                                                force_context[force_pos]]->type)
562                                                 force_pos--;
563                                         o[osize] = force_context[force_pos];
564                                         if (recurse_to_leaf)
565                                                 c[osize] = force_context[0];
566                                         j++;
567                                         force_pos--;
568                                 }
569                                 osize += crush_choose(map,
570                                                       map->buckets[-1-w[i]],
571                                                       weight,
572                                                       x, numrep,
573                                                       rule->steps[step].arg2,
574                                                       o+osize, j,
575                                                       firstn,
576                                                       recurse_to_leaf, c+osize);
577                         }
578
579                         if (recurse_to_leaf)
580                                 /* copy final _leaf_ values to output set */
581                                 memcpy(o, c, osize*sizeof(*o));
582
583                         /* swap t and w arrays */
584                         tmp = o;
585                         o = w;
586                         w = tmp;
587                         wsize = osize;
588                         break;
589
590
591                 case CRUSH_RULE_EMIT:
592                         for (i = 0; i < wsize && result_len < result_max; i++) {
593                                 result[result_len] = w[i];
594                                 result_len++;
595                         }
596                         wsize = 0;
597                         break;
598
599                 default:
600                         BUG_ON(1);
601                 }
602         }
603         rc = result_len;
604
605 out:
606         return rc;
607 }
608
609