#ifdef __KERNEL__ # include <linux/string.h> # include <linux/slab.h> # include <linux/bug.h> # include <linux/kernel.h> # ifndef dprintk # define dprintk(args...) # endif #else # include <string.h> # include <stdio.h> # include <stdlib.h> # include <assert.h> # define BUG_ON(x) assert(!(x)) # define dprintk(args...) /* printf(args) */ # define kmalloc(x, f) malloc(x) # define kfree(x) free(x) #endif #include "crush.h" #include "hash.h" /* * Implement the core CRUSH mapping algorithm. */ /** * crush_find_rule - find a crush_rule id for a given ruleset, type, and size. * @map: the crush_map * @ruleset: the storage ruleset id (user defined) * @type: storage ruleset type (user defined) * @size: output set size */ int crush_find_rule(struct crush_map *map, int ruleset, int type, int size) { int i; for (i = 0; i < map->max_rules; i++) { if (map->rules[i] && map->rules[i]->mask.ruleset == ruleset && map->rules[i]->mask.type == type && map->rules[i]->mask.min_size <= size && map->rules[i]->mask.max_size >= size) return i; } return -1; } /* * bucket choose methods * * For each bucket algorithm, we have a "choose" method that, given a * crush input @x and replica position (usually, position in output set) @r, * will produce an item in the bucket. */ /* * Choose based on a random permutation of the bucket. * * We used to use some prime number arithmetic to do this, but it * wasn't very random, and had some other bad behaviors. Instead, we * calculate an actual random permutation of the bucket members. * Since this is expensive, we optimize for the r=0 case, which * captures the vast majority of calls. */ static int bucket_perm_choose(struct crush_bucket *bucket, int x, int r) { unsigned pr = r % bucket->size; unsigned i, s; /* start a new permutation if @x has changed */ if (bucket->perm_x != x || bucket->perm_n == 0) { dprintk("bucket %d new x=%d\n", bucket->id, x); bucket->perm_x = x; /* optimize common r=0 case */ if (pr == 0) { s = crush_hash32_3(bucket->hash, x, bucket->id, 0) % bucket->size; bucket->perm[0] = s; bucket->perm_n = 0xffff; /* magic value, see below */ goto out; } for (i = 0; i < bucket->size; i++) bucket->perm[i] = i; bucket->perm_n = 0; } else if (bucket->perm_n == 0xffff) { /* clean up after the r=0 case above */ for (i = 1; i < bucket->size; i++) bucket->perm[i] = i; bucket->perm[bucket->perm[0]] = 0; bucket->perm_n = 1; } /* calculate permutation up to pr */ for (i = 0; i < bucket->perm_n; i++) dprintk(" perm_choose have %d: %d\n", i, bucket->perm[i]); while (bucket->perm_n <= pr) { unsigned p = bucket->perm_n; /* no point in swapping the final entry */ if (p < bucket->size - 1) { i = crush_hash32_3(bucket->hash, x, bucket->id, p) % (bucket->size - p); if (i) { unsigned t = bucket->perm[p + i]; bucket->perm[p + i] = bucket->perm[p]; bucket->perm[p] = t; } dprintk(" perm_choose swap %d with %d\n", p, p+i); } bucket->perm_n++; } for (i = 0; i < bucket->size; i++) dprintk(" perm_choose %d: %d\n", i, bucket->perm[i]); s = bucket->perm[pr]; out: dprintk(" perm_choose %d sz=%d x=%d r=%d (%d) s=%d\n", bucket->id, bucket->size, x, r, pr, s); return bucket->items[s]; } /* uniform */ static int bucket_uniform_choose(struct crush_bucket_uniform *bucket, int x, int r) { return bucket_perm_choose(&bucket->h, x, r); } /* list */ static int bucket_list_choose(struct crush_bucket_list *bucket, int x, int r) { int i; for (i = bucket->h.size-1; i >= 0; i--) { __u64 w = crush_hash32_4(bucket->h.hash,x, bucket->h.items[i], r, bucket->h.id); w &= 0xffff; dprintk("list_choose i=%d x=%d r=%d item %d weight %x " "sw %x rand %llx", i, x, r, bucket->h.items[i], bucket->item_weights[i], bucket->sum_weights[i], w); w *= bucket->sum_weights[i]; w = w >> 16; /*dprintk(" scaled %llx\n", w);*/ if (w < bucket->item_weights[i]) return bucket->h.items[i]; } BUG_ON(1); return 0; } /* (binary) tree */ static int height(int n) { int h = 0; while ((n & 1) == 0) { h++; n = n >> 1; } return h; } static int left(int x) { int h = height(x); return x - (1 << (h-1)); } static int right(int x) { int h = height(x); return x + (1 << (h-1)); } static int terminal(int x) { return x & 1; } static int bucket_tree_choose(struct crush_bucket_tree *bucket, int x, int r) { int n, l; __u32 w; __u64 t; /* start at root */ n = bucket->num_nodes >> 1; while (!terminal(n)) { /* pick point in [0, w) */ w = bucket->node_weights[n]; t = (__u64)crush_hash32_4(bucket->h.hash, x, n, r, bucket->h.id) * (__u64)w; t = t >> 32; /* descend to the left or right? */ l = left(n); if (t < bucket->node_weights[l]) n = l; else n = right(n); } return bucket->h.items[n >> 1]; } /* straw */ static int bucket_straw_choose(struct crush_bucket_straw *bucket, int x, int r) { int i; int high = 0; __u64 high_draw = 0; __u64 draw; for (i = 0; i < bucket->h.size; i++) { draw = crush_hash32_3(bucket->h.hash, x, bucket->h.items[i], r); draw &= 0xffff; draw *= bucket->straws[i]; if (i == 0 || draw > high_draw) { high = i; high_draw = draw; } } return bucket->h.items[high]; } static int crush_bucket_choose(struct crush_bucket *in, int x, int r) { dprintk("choose %d x=%d r=%d\n", in->id, x, r); switch (in->alg) { case CRUSH_BUCKET_UNIFORM: return bucket_uniform_choose((struct crush_bucket_uniform *)in, x, r); case CRUSH_BUCKET_LIST: return bucket_list_choose((struct crush_bucket_list *)in, x, r); case CRUSH_BUCKET_TREE: return bucket_tree_choose((struct crush_bucket_tree *)in, x, r); case CRUSH_BUCKET_STRAW: return bucket_straw_choose((struct crush_bucket_straw *)in, x, r); default: BUG_ON(1); return in->items[0]; } } /* * true if device is marked "out" (failed, fully offloaded) * of the cluster */ static int is_out(struct crush_map *map, __u32 *weight, int item, int x) { if (weight[item] >= 0x1000) return 0; if (weight[item] == 0) return 1; if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff) < weight[item]) return 0; return 1; } /** * crush_choose - choose numrep distinct items of given type * @map: the crush_map * @bucket: the bucket we are choose an item from * @x: crush input value * @numrep: the number of items to choose * @type: the type of item to choose * @out: pointer to output vector * @outpos: our position in that vector * @firstn: true if choosing "first n" items, false if choosing "indep" * @recurse_to_leaf: true if we want one device under each item of given type * @out2: second output vector for leaf items (if @recurse_to_leaf) */ static int crush_choose(struct crush_map *map, struct crush_bucket *bucket, __u32 *weight, int x, int numrep, int type, int *out, int outpos, int firstn, int recurse_to_leaf, int *out2) { int rep; int ftotal, flocal; int retry_descent, retry_bucket, skip_rep; struct crush_bucket *in = bucket; int r; int i; int item = 0; int itemtype; int collide, reject; const int orig_tries = 5; /* attempts before we fall back to search */ dprintk("choose bucket %d x %d outpos %d\n", bucket->id, x, outpos); for (rep = outpos; rep < numrep; rep++) { /* keep trying until we get a non-out, non-colliding item */ ftotal = 0; skip_rep = 0; do { retry_descent = 0; in = bucket; /* initial bucket */ /* choose through intervening buckets */ flocal = 0; do { collide = 0; retry_bucket = 0; r = rep; if (in->alg == CRUSH_BUCKET_UNIFORM) { /* be careful */ if (firstn || numrep >= in->size) /* r' = r + f_total */ r += ftotal; else if (in->size % numrep == 0) /* r'=r+(n+1)*f_local */ r += (numrep+1) * (flocal+ftotal); else /* r' = r + n*f_local */ r += numrep * (flocal+ftotal); } else { if (firstn) /* r' = r + f_total */ r += ftotal; else /* r' = r + n*f_local */ r += numrep * (flocal+ftotal); } /* bucket choose */ if (in->size == 0) { reject = 1; goto reject; } if (flocal >= (in->size>>1) && flocal > orig_tries) item = bucket_perm_choose(in, x, r); else item = crush_bucket_choose(in, x, r); BUG_ON(item >= map->max_devices); /* desired type? */ if (item < 0) itemtype = map->buckets[-1-item]->type; else itemtype = 0; dprintk(" item %d type %d\n", item, itemtype); /* keep going? */ if (itemtype != type) { BUG_ON(item >= 0 || (-1-item) >= map->max_buckets); in = map->buckets[-1-item]; continue; } /* collision? */ for (i = 0; i < outpos; i++) { if (out[i] == item) { collide = 1; break; } } if (recurse_to_leaf && item < 0 && crush_choose(map, map->buckets[-1-item], weight, x, outpos+1, 0, out2, outpos, firstn, 0, NULL) <= outpos) { reject = 1; } else { /* out? */ if (itemtype == 0) reject = is_out(map, weight, item, x); else reject = 0; } reject: if (reject || collide) { ftotal++; flocal++; if (collide && flocal < 3) /* retry locally a few times */ retry_bucket = 1; else if (flocal < in->size + orig_tries) /* exhaustive bucket search */ retry_bucket = 1; else if (ftotal < 20) /* then retry descent */ retry_descent = 1; else /* else give up */ skip_rep = 1; dprintk(" reject %d collide %d " "ftotal %d flocal %d\n", reject, collide, ftotal, flocal); } } while (retry_bucket); } while (retry_descent); if (skip_rep) { dprintk("skip rep\n"); continue; } dprintk("choose got %d\n", item); out[outpos] = item; outpos++; } dprintk("choose returns %d\n", outpos); return outpos; } /** * crush_do_rule - calculate a mapping with the given input and rule * @map: the crush_map * @ruleno: the rule id * @x: hash input * @result: pointer to result vector * @result_max: maximum result size * @force: force initial replica choice; -1 for none */ int crush_do_rule(struct crush_map *map, int ruleno, int x, int *result, int result_max, int force, __u32 *weight) { int result_len; int force_context[CRUSH_MAX_DEPTH]; int force_pos = -1; int a[CRUSH_MAX_SET]; int b[CRUSH_MAX_SET]; int c[CRUSH_MAX_SET]; int recurse_to_leaf; int *w; int wsize = 0; int *o; int osize; int *tmp; struct crush_rule *rule; int step; int i, j; int numrep; int firstn; int rc = -1; BUG_ON(ruleno >= map->max_rules); rule = map->rules[ruleno]; result_len = 0; w = a; o = b; /* * determine hierarchical context of force, if any. note * that this may or may not correspond to the specific types * referenced by the crush rule. */ if (force >= 0) { if (force >= map->max_devices || map->device_parents[force] == 0) { /*dprintk("CRUSH: forcefed device dne\n");*/ rc = -1; /* force fed device dne */ goto out; } if (!is_out(map, weight, force, x)) { while (1) { force_context[++force_pos] = force; if (force >= 0) force = map->device_parents[force]; else force = map->bucket_parents[-1-force]; if (force == 0) break; } } } for (step = 0; step < rule->len; step++) { firstn = 0; switch (rule->steps[step].op) { case CRUSH_RULE_TAKE: w[0] = rule->steps[step].arg1; if (force_pos >= 0) { BUG_ON(force_context[force_pos] != w[0]); force_pos--; } wsize = 1; break; case CRUSH_RULE_CHOOSE_LEAF_FIRSTN: case CRUSH_RULE_CHOOSE_FIRSTN: firstn = 1; case CRUSH_RULE_CHOOSE_LEAF_INDEP: case CRUSH_RULE_CHOOSE_INDEP: BUG_ON(wsize == 0); recurse_to_leaf = rule->steps[step].op == CRUSH_RULE_CHOOSE_LEAF_FIRSTN || rule->steps[step].op == CRUSH_RULE_CHOOSE_LEAF_INDEP; /* reset output */ osize = 0; for (i = 0; i < wsize; i++) { /* * see CRUSH_N, CRUSH_N_MINUS macros. * basically, numrep <= 0 means relative to * the provided result_max */ numrep = rule->steps[step].arg1; if (numrep <= 0) { numrep += result_max; if (numrep <= 0) continue; } j = 0; if (osize == 0 && force_pos >= 0) { /* skip any intermediate types */ while (force_pos && force_context[force_pos] < 0 && rule->steps[step].arg2 != map->buckets[-1 - force_context[force_pos]]->type) force_pos--; o[osize] = force_context[force_pos]; if (recurse_to_leaf) c[osize] = force_context[0]; j++; force_pos--; } osize += crush_choose(map, map->buckets[-1-w[i]], weight, x, numrep, rule->steps[step].arg2, o+osize, j, firstn, recurse_to_leaf, c+osize); } if (recurse_to_leaf) /* copy final _leaf_ values to output set */ memcpy(o, c, osize*sizeof(*o)); /* swap t and w arrays */ tmp = o; o = w; w = tmp; wsize = osize; break; case CRUSH_RULE_EMIT: for (i = 0; i < wsize && result_len < result_max; i++) { result[result_len] = w[i]; result_len++; } wsize = 0; break; default: BUG_ON(1); } } rc = result_len; out: return rc; }