/* * Ceph - scalable distributed file system * * Copyright (C) 2015 Intel Corporation All Rights Reserved * * This is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License version 2.1, as published by the Free Software * Foundation. See file COPYING. * */ #ifdef __KERNEL__ # include <linux/string.h> # include <linux/slab.h> # include <linux/bug.h> # include <linux/kernel.h> # include <linux/crush/crush.h> # include <linux/crush/hash.h> # include <linux/crush/mapper.h> #else # include "crush_compat.h" # include "crush.h" # include "hash.h" # include "mapper.h" #endif #include "crush_ln_table.h" #define dprintk(args...) /* printf(args) */ /* * 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(const struct crush_map *map, int ruleset, int type, int size) { __u32 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 int pr = r % bucket->size; unsigned int i, s; /* start a new permutation if @x has changed */ if (bucket->perm_x != (__u32)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 int 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 int 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]; } dprintk("bad list sums for bucket %d\n", bucket->h.id); return bucket->h.items[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; __u32 w; __u64 t; /* start at root */ n = bucket->num_nodes >> 1; while (!terminal(n)) { int l; /* 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) { __u32 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]; } /* compute 2^44*log2(input+1) */ static __u64 crush_ln(unsigned int xin) { unsigned int x = xin; int iexpon, index1, index2; __u64 RH, LH, LL, xl64, result; x++; /* normalize input */ iexpon = 15; /* * figure out number of bits we need to shift and * do it in one step instead of iteratively */ if (!(x & 0x18000)) { int bits = __builtin_clz(x & 0x1FFFF) - 16; x <<= bits; iexpon = 15 - bits; } index1 = (x >> 8) << 1; /* RH ~ 2^56/index1 */ RH = __RH_LH_tbl[index1 - 256]; /* LH ~ 2^48 * log2(index1/256) */ LH = __RH_LH_tbl[index1 + 1 - 256]; /* RH*x ~ 2^48 * (2^15 + xf), xf<2^8 */ xl64 = (__s64)x * RH; xl64 >>= 48; result = iexpon; result <<= (12 + 32); index2 = xl64 & 0xff; /* LL ~ 2^48*log2(1.0+index2/2^15) */ LL = __LL_tbl[index2]; LH = LH + LL; LH >>= (48 - 12 - 32); result += LH; return result; } /* * straw2 * * for reference, see: * * http://en.wikipedia.org/wiki/Exponential_distribution#Distribution_of_the_minimum_of_exponential_random_variables * */ static int bucket_straw2_choose(struct crush_bucket_straw2 *bucket, int x, int r) { unsigned int i, high = 0; unsigned int u; unsigned int w; __s64 ln, draw, high_draw = 0; for (i = 0; i < bucket->h.size; i++) { w = bucket->item_weights[i]; if (w) { u = crush_hash32_3(bucket->h.hash, x, bucket->h.items[i], r); u &= 0xffff; /* * for some reason slightly less than 0x10000 produces * a slightly more accurate distribution... probably a * rounding effect. * * the natural log lookup table maps [0,0xffff] * (corresponding to real numbers [1/0x10000, 1] to * [0, 0xffffffffffff] (corresponding to real numbers * [-11.090355,0]). */ ln = crush_ln(u) - 0x1000000000000ll; /* * divide by 16.16 fixed-point weight. note * that the ln value is negative, so a larger * weight means a larger (less negative) value * for draw. */ draw = div64_s64(ln, w); } else { draw = S64_MIN; } 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(" crush_bucket_choose %d x=%d r=%d\n", in->id, x, r); BUG_ON(in->size == 0); 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); case CRUSH_BUCKET_STRAW2: return bucket_straw2_choose((struct crush_bucket_straw2 *)in, x, r); default: dprintk("unknown bucket %d alg %d\n", in->id, in->alg); return in->items[0]; } } /* * true if device is marked "out" (failed, fully offloaded) * of the cluster */ static int is_out(const struct crush_map *map, const __u32 *weight, int weight_max, int item, int x) { if (item >= weight_max) return 1; if (weight[item] >= 0x10000) 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_firstn - 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 * @out_size: size of the out vector * @tries: number of attempts to make * @recurse_tries: number of attempts to have recursive chooseleaf make * @local_retries: localized retries * @local_fallback_retries: localized fallback retries * @recurse_to_leaf: true if we want one device under each item of given type (chooseleaf instead of choose) * @stable: stable mode starts rep=0 in the recursive call for all replicas * @vary_r: pass r to recursive calls * @out2: second output vector for leaf items (if @recurse_to_leaf) * @parent_r: r value passed from the parent */ static int crush_choose_firstn(const struct crush_map *map, struct crush_bucket *bucket, const __u32 *weight, int weight_max, int x, int numrep, int type, int *out, int outpos, int out_size, unsigned int tries, unsigned int recurse_tries, unsigned int local_retries, unsigned int local_fallback_retries, int recurse_to_leaf, unsigned int vary_r, unsigned int stable, int *out2, int parent_r) { int rep; unsigned 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; int count = out_size; 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", recurse_to_leaf ? "_LEAF" : "", bucket->id, x, outpos, numrep, tries, recurse_tries, local_retries, local_fallback_retries, parent_r, stable); for (rep = stable ? 0 : outpos; rep < numrep && count > 0 ; 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 + parent_r; /* r' = r + f_total */ r += ftotal; /* bucket choose */ if (in->size == 0) { reject = 1; goto reject; } if (local_fallback_retries > 0 && flocal >= (in->size>>1) && flocal > local_fallback_retries) item = bucket_perm_choose(in, x, r); else item = crush_bucket_choose(in, x, r); if (item >= map->max_devices) { dprintk(" bad item %d\n", item); skip_rep = 1; break; } /* 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) { if (item >= 0 || (-1-item) >= map->max_buckets) { dprintk(" bad item type %d\n", type); skip_rep = 1; break; } in = map->buckets[-1-item]; retry_bucket = 1; continue; } /* collision? */ for (i = 0; i < outpos; i++) { if (out[i] == item) { collide = 1; break; } } reject = 0; if (!collide && recurse_to_leaf) { if (item < 0) { int sub_r; if (vary_r) sub_r = r >> (vary_r-1); else sub_r = 0; if (crush_choose_firstn(map, map->buckets[-1-item], weight, weight_max, x, stable ? 1 : outpos+1, 0, out2, outpos, count, recurse_tries, 0, local_retries, local_fallback_retries, 0, vary_r, stable, NULL, sub_r) <= outpos) /* didn't get leaf */ reject = 1; } else { /* we already have a leaf! */ out2[outpos] = item; } } if (!reject) { /* out? */ if (itemtype == 0) reject = is_out(map, weight, weight_max, item, x); else reject = 0; } reject: if (reject || collide) { ftotal++; flocal++; if (collide && flocal <= local_retries) /* retry locally a few times */ retry_bucket = 1; else if (local_fallback_retries > 0 && flocal <= in->size + local_fallback_retries) /* exhaustive bucket search */ retry_bucket = 1; else if (ftotal < tries) /* then retry descent */ retry_descent = 1; else /* else give up */ skip_rep = 1; dprintk(" reject %d collide %d " "ftotal %u flocal %u\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++; count--; #ifndef __KERNEL__ if (map->choose_tries && ftotal <= map->choose_total_tries) map->choose_tries[ftotal]++; #endif } dprintk("CHOOSE returns %d\n", outpos); return outpos; } /** * crush_choose_indep: alternative breadth-first positionally stable mapping * */ static void crush_choose_indep(const struct crush_map *map, struct crush_bucket *bucket, const __u32 *weight, int weight_max, int x, int left, int numrep, int type, int *out, int outpos, unsigned int tries, unsigned int recurse_tries, int recurse_to_leaf, int *out2, int parent_r) { struct crush_bucket *in = bucket; int endpos = outpos + left; int rep; unsigned int ftotal; int r; int i; int item = 0; int itemtype; int collide; dprintk("CHOOSE%s INDEP bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "", bucket->id, x, outpos, numrep); /* initially my result is undefined */ for (rep = outpos; rep < endpos; rep++) { out[rep] = CRUSH_ITEM_UNDEF; if (out2) out2[rep] = CRUSH_ITEM_UNDEF; } for (ftotal = 0; left > 0 && ftotal < tries; ftotal++) { #ifdef DEBUG_INDEP if (out2 && ftotal) { dprintk("%u %d a: ", ftotal, left); for (rep = outpos; rep < endpos; rep++) { dprintk(" %d", out[rep]); } dprintk("\n"); dprintk("%u %d b: ", ftotal, left); for (rep = outpos; rep < endpos; rep++) { dprintk(" %d", out2[rep]); } dprintk("\n"); } #endif for (rep = outpos; rep < endpos; rep++) { if (out[rep] != CRUSH_ITEM_UNDEF) continue; in = bucket; /* initial bucket */ /* choose through intervening buckets */ for (;;) { /* note: we base the choice on the position * even in the nested call. that means that * if the first layer chooses the same bucket * in a different position, we will tend to * choose a different item in that bucket. * this will involve more devices in data * movement and tend to distribute the load. */ r = rep + parent_r; /* be careful */ if (in->alg == CRUSH_BUCKET_UNIFORM && in->size % numrep == 0) /* r'=r+(n+1)*f_total */ r += (numrep+1) * ftotal; else /* r' = r + n*f_total */ r += numrep * ftotal; /* bucket choose */ if (in->size == 0) { dprintk(" empty bucket\n"); break; } item = crush_bucket_choose(in, x, r); if (item >= map->max_devices) { dprintk(" bad item %d\n", item); out[rep] = CRUSH_ITEM_NONE; if (out2) out2[rep] = CRUSH_ITEM_NONE; left--; break; } /* 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) { if (item >= 0 || (-1-item) >= map->max_buckets) { dprintk(" bad item type %d\n", type); out[rep] = CRUSH_ITEM_NONE; if (out2) out2[rep] = CRUSH_ITEM_NONE; left--; break; } in = map->buckets[-1-item]; continue; } /* collision? */ collide = 0; for (i = outpos; i < endpos; i++) { if (out[i] == item) { collide = 1; break; } } if (collide) break; if (recurse_to_leaf) { if (item < 0) { crush_choose_indep(map, map->buckets[-1-item], weight, weight_max, x, 1, numrep, 0, out2, rep, recurse_tries, 0, 0, NULL, r); if (out2[rep] == CRUSH_ITEM_NONE) { /* placed nothing; no leaf */ break; } } else { /* we already have a leaf! */ out2[rep] = item; } } /* out? */ if (itemtype == 0 && is_out(map, weight, weight_max, item, x)) break; /* yay! */ out[rep] = item; left--; break; } } } for (rep = outpos; rep < endpos; rep++) { if (out[rep] == CRUSH_ITEM_UNDEF) { out[rep] = CRUSH_ITEM_NONE; } if (out2 && out2[rep] == CRUSH_ITEM_UNDEF) { out2[rep] = CRUSH_ITEM_NONE; } } #ifndef __KERNEL__ if (map->choose_tries && ftotal <= map->choose_total_tries) map->choose_tries[ftotal]++; #endif #ifdef DEBUG_INDEP if (out2) { dprintk("%u %d a: ", ftotal, left); for (rep = outpos; rep < endpos; rep++) { dprintk(" %d", out[rep]); } dprintk("\n"); dprintk("%u %d b: ", ftotal, left); for (rep = outpos; rep < endpos; rep++) { dprintk(" %d", out2[rep]); } dprintk("\n"); } #endif } /** * 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 * @weight: weight vector (for map leaves) * @weight_max: size of weight vector * @scratch: scratch vector for private use; must be >= 3 * result_max */ int crush_do_rule(const struct crush_map *map, int ruleno, int x, int *result, int result_max, const __u32 *weight, int weight_max, int *scratch) { int result_len; int *a = scratch; int *b = scratch + result_max; int *c = scratch + result_max*2; int recurse_to_leaf; int *w; int wsize = 0; int *o; int osize; int *tmp; struct crush_rule *rule; __u32 step; int i, j; int numrep; int out_size; /* * the original choose_total_tries value was off by one (it * counted "retries" and not "tries"). add one. */ int choose_tries = map->choose_total_tries + 1; int choose_leaf_tries = 0; /* * the local tries values were counted as "retries", though, * and need no adjustment */ int choose_local_retries = map->choose_local_tries; int choose_local_fallback_retries = map->choose_local_fallback_tries; int vary_r = map->chooseleaf_vary_r; int stable = map->chooseleaf_stable; if ((__u32)ruleno >= map->max_rules) { dprintk(" bad ruleno %d\n", ruleno); return 0; } rule = map->rules[ruleno]; result_len = 0; w = a; o = b; for (step = 0; step < rule->len; step++) { int firstn = 0; struct crush_rule_step *curstep = &rule->steps[step]; switch (curstep->op) { case CRUSH_RULE_TAKE: if ((curstep->arg1 >= 0 && curstep->arg1 < map->max_devices) || (-1-curstep->arg1 >= 0 && -1-curstep->arg1 < map->max_buckets && map->buckets[-1-curstep->arg1])) { w[0] = curstep->arg1; wsize = 1; } else { dprintk(" bad take value %d\n", curstep->arg1); } break; case CRUSH_RULE_SET_CHOOSE_TRIES: if (curstep->arg1 > 0) choose_tries = curstep->arg1; break; case CRUSH_RULE_SET_CHOOSELEAF_TRIES: if (curstep->arg1 > 0) choose_leaf_tries = curstep->arg1; break; case CRUSH_RULE_SET_CHOOSE_LOCAL_TRIES: if (curstep->arg1 >= 0) choose_local_retries = curstep->arg1; break; case CRUSH_RULE_SET_CHOOSE_LOCAL_FALLBACK_TRIES: if (curstep->arg1 >= 0) choose_local_fallback_retries = curstep->arg1; break; case CRUSH_RULE_SET_CHOOSELEAF_VARY_R: if (curstep->arg1 >= 0) vary_r = curstep->arg1; break; case CRUSH_RULE_SET_CHOOSELEAF_STABLE: if (curstep->arg1 >= 0) stable = curstep->arg1; break; case CRUSH_RULE_CHOOSELEAF_FIRSTN: case CRUSH_RULE_CHOOSE_FIRSTN: firstn = 1; /* fall through */ case CRUSH_RULE_CHOOSELEAF_INDEP: case CRUSH_RULE_CHOOSE_INDEP: if (wsize == 0) break; recurse_to_leaf = curstep->op == CRUSH_RULE_CHOOSELEAF_FIRSTN || curstep->op == CRUSH_RULE_CHOOSELEAF_INDEP; /* reset output */ osize = 0; for (i = 0; i < wsize; i++) { int bno; /* * see CRUSH_N, CRUSH_N_MINUS macros. * basically, numrep <= 0 means relative to * the provided result_max */ numrep = curstep->arg1; if (numrep <= 0) { numrep += result_max; if (numrep <= 0) continue; } j = 0; /* make sure bucket id is valid */ bno = -1 - w[i]; if (bno < 0 || bno >= map->max_buckets) { /* w[i] is probably CRUSH_ITEM_NONE */ dprintk(" bad w[i] %d\n", w[i]); continue; } if (firstn) { int recurse_tries; if (choose_leaf_tries) recurse_tries = choose_leaf_tries; else if (map->chooseleaf_descend_once) recurse_tries = 1; else recurse_tries = choose_tries; osize += crush_choose_firstn( map, map->buckets[bno], weight, weight_max, x, numrep, curstep->arg2, o+osize, j, result_max-osize, choose_tries, recurse_tries, choose_local_retries, choose_local_fallback_retries, recurse_to_leaf, vary_r, stable, c+osize, 0); } else { out_size = ((numrep < (result_max-osize)) ? numrep : (result_max-osize)); crush_choose_indep( map, map->buckets[bno], weight, weight_max, x, out_size, numrep, curstep->arg2, o+osize, j, choose_tries, choose_leaf_tries ? choose_leaf_tries : 1, recurse_to_leaf, c+osize, 0); osize += out_size; } } if (recurse_to_leaf) /* copy final _leaf_ values to output set */ memcpy(o, c, osize*sizeof(*o)); /* swap o 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: dprintk(" unknown op %d at step %d\n", curstep->op, step); break; } } return result_len; }