606 lines
14 KiB
C
606 lines
14 KiB
C
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#ifdef __KERNEL__
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# include <linux/string.h>
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# include <linux/slab.h>
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# include <linux/bug.h>
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# include <linux/kernel.h>
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# ifndef dprintk
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# define dprintk(args...)
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# endif
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#else
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# include <string.h>
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# include <stdio.h>
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# include <stdlib.h>
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# include <assert.h>
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# define BUG_ON(x) assert(!(x))
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# define dprintk(args...) /* printf(args) */
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# define kmalloc(x, f) malloc(x)
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# define kfree(x) free(x)
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#endif
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#include <linux/crush/crush.h>
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#include <linux/crush/hash.h>
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/*
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* Implement the core CRUSH mapping algorithm.
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*/
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/**
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* crush_find_rule - find a crush_rule id for a given ruleset, type, and size.
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* @map: the crush_map
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* @ruleset: the storage ruleset id (user defined)
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* @type: storage ruleset type (user defined)
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* @size: output set size
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*/
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int crush_find_rule(struct crush_map *map, int ruleset, int type, int size)
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{
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int i;
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for (i = 0; i < map->max_rules; i++) {
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if (map->rules[i] &&
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map->rules[i]->mask.ruleset == ruleset &&
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map->rules[i]->mask.type == type &&
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map->rules[i]->mask.min_size <= size &&
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map->rules[i]->mask.max_size >= size)
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return i;
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}
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return -1;
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}
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/*
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* bucket choose methods
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*
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* For each bucket algorithm, we have a "choose" method that, given a
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* crush input @x and replica position (usually, position in output set) @r,
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* will produce an item in the bucket.
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*/
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/*
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* Choose based on a random permutation of the bucket.
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*
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* We used to use some prime number arithmetic to do this, but it
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* wasn't very random, and had some other bad behaviors. Instead, we
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* calculate an actual random permutation of the bucket members.
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* Since this is expensive, we optimize for the r=0 case, which
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* captures the vast majority of calls.
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*/
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static int bucket_perm_choose(struct crush_bucket *bucket,
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int x, int r)
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{
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unsigned pr = r % bucket->size;
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unsigned i, s;
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/* start a new permutation if @x has changed */
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if (bucket->perm_x != x || bucket->perm_n == 0) {
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dprintk("bucket %d new x=%d\n", bucket->id, x);
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bucket->perm_x = x;
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/* optimize common r=0 case */
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if (pr == 0) {
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s = crush_hash32_3(bucket->hash, x, bucket->id, 0) %
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bucket->size;
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bucket->perm[0] = s;
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bucket->perm_n = 0xffff; /* magic value, see below */
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goto out;
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}
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for (i = 0; i < bucket->size; i++)
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bucket->perm[i] = i;
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bucket->perm_n = 0;
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} else if (bucket->perm_n == 0xffff) {
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/* clean up after the r=0 case above */
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for (i = 1; i < bucket->size; i++)
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bucket->perm[i] = i;
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bucket->perm[bucket->perm[0]] = 0;
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bucket->perm_n = 1;
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}
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/* calculate permutation up to pr */
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for (i = 0; i < bucket->perm_n; i++)
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dprintk(" perm_choose have %d: %d\n", i, bucket->perm[i]);
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while (bucket->perm_n <= pr) {
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unsigned p = bucket->perm_n;
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/* no point in swapping the final entry */
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if (p < bucket->size - 1) {
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i = crush_hash32_3(bucket->hash, x, bucket->id, p) %
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(bucket->size - p);
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if (i) {
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unsigned t = bucket->perm[p + i];
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bucket->perm[p + i] = bucket->perm[p];
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bucket->perm[p] = t;
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}
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dprintk(" perm_choose swap %d with %d\n", p, p+i);
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}
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bucket->perm_n++;
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}
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for (i = 0; i < bucket->size; i++)
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dprintk(" perm_choose %d: %d\n", i, bucket->perm[i]);
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s = bucket->perm[pr];
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out:
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dprintk(" perm_choose %d sz=%d x=%d r=%d (%d) s=%d\n", bucket->id,
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bucket->size, x, r, pr, s);
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return bucket->items[s];
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}
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/* uniform */
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static int bucket_uniform_choose(struct crush_bucket_uniform *bucket,
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int x, int r)
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{
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return bucket_perm_choose(&bucket->h, x, r);
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}
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/* list */
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static int bucket_list_choose(struct crush_bucket_list *bucket,
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int x, int r)
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{
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int i;
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for (i = bucket->h.size-1; i >= 0; i--) {
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__u64 w = crush_hash32_4(bucket->h.hash,x, bucket->h.items[i],
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r, bucket->h.id);
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w &= 0xffff;
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dprintk("list_choose i=%d x=%d r=%d item %d weight %x "
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"sw %x rand %llx",
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i, x, r, bucket->h.items[i], bucket->item_weights[i],
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bucket->sum_weights[i], w);
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w *= bucket->sum_weights[i];
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w = w >> 16;
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/*dprintk(" scaled %llx\n", w);*/
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if (w < bucket->item_weights[i])
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return bucket->h.items[i];
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}
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BUG_ON(1);
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return 0;
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}
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/* (binary) tree */
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static int height(int n)
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{
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int h = 0;
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while ((n & 1) == 0) {
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h++;
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n = n >> 1;
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}
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return h;
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}
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static int left(int x)
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{
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int h = height(x);
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return x - (1 << (h-1));
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}
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static int right(int x)
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{
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int h = height(x);
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return x + (1 << (h-1));
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}
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static int terminal(int x)
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{
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return x & 1;
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}
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static int bucket_tree_choose(struct crush_bucket_tree *bucket,
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int x, int r)
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{
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int n, l;
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__u32 w;
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__u64 t;
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/* start at root */
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n = bucket->num_nodes >> 1;
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while (!terminal(n)) {
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/* pick point in [0, w) */
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w = bucket->node_weights[n];
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t = (__u64)crush_hash32_4(bucket->h.hash, x, n, r,
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bucket->h.id) * (__u64)w;
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t = t >> 32;
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/* descend to the left or right? */
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l = left(n);
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if (t < bucket->node_weights[l])
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n = l;
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else
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n = right(n);
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}
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return bucket->h.items[n >> 1];
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}
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/* straw */
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static int bucket_straw_choose(struct crush_bucket_straw *bucket,
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int x, int r)
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{
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int i;
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int high = 0;
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__u64 high_draw = 0;
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__u64 draw;
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for (i = 0; i < bucket->h.size; i++) {
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draw = crush_hash32_3(bucket->h.hash, x, bucket->h.items[i], r);
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draw &= 0xffff;
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draw *= bucket->straws[i];
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if (i == 0 || draw > high_draw) {
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high = i;
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high_draw = draw;
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}
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}
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return bucket->h.items[high];
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}
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static int crush_bucket_choose(struct crush_bucket *in, int x, int r)
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{
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dprintk(" crush_bucket_choose %d x=%d r=%d\n", in->id, x, r);
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switch (in->alg) {
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case CRUSH_BUCKET_UNIFORM:
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return bucket_uniform_choose((struct crush_bucket_uniform *)in,
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x, r);
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case CRUSH_BUCKET_LIST:
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return bucket_list_choose((struct crush_bucket_list *)in,
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x, r);
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case CRUSH_BUCKET_TREE:
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return bucket_tree_choose((struct crush_bucket_tree *)in,
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x, r);
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case CRUSH_BUCKET_STRAW:
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return bucket_straw_choose((struct crush_bucket_straw *)in,
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x, r);
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default:
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BUG_ON(1);
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return in->items[0];
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}
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}
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/*
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* true if device is marked "out" (failed, fully offloaded)
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* of the cluster
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*/
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static int is_out(struct crush_map *map, __u32 *weight, int item, int x)
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{
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if (weight[item] >= 0x10000)
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return 0;
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if (weight[item] == 0)
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return 1;
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if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff)
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< weight[item])
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return 0;
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return 1;
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}
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/**
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* crush_choose - choose numrep distinct items of given type
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* @map: the crush_map
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* @bucket: the bucket we are choose an item from
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* @x: crush input value
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* @numrep: the number of items to choose
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* @type: the type of item to choose
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* @out: pointer to output vector
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* @outpos: our position in that vector
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* @firstn: true if choosing "first n" items, false if choosing "indep"
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* @recurse_to_leaf: true if we want one device under each item of given type
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* @out2: second output vector for leaf items (if @recurse_to_leaf)
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*/
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static int crush_choose(struct crush_map *map,
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struct crush_bucket *bucket,
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__u32 *weight,
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int x, int numrep, int type,
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int *out, int outpos,
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int firstn, int recurse_to_leaf,
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int *out2)
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{
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int rep;
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int ftotal, flocal;
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int retry_descent, retry_bucket, skip_rep;
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struct crush_bucket *in = bucket;
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int r;
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int i;
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int item = 0;
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int itemtype;
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int collide, reject;
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const int orig_tries = 5; /* attempts before we fall back to search */
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dprintk("CHOOSE%s bucket %d x %d outpos %d numrep %d\n", recurse_to_leaf ? "_LEAF" : "",
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bucket->id, x, outpos, numrep);
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for (rep = outpos; rep < numrep; rep++) {
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/* keep trying until we get a non-out, non-colliding item */
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ftotal = 0;
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skip_rep = 0;
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do {
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retry_descent = 0;
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in = bucket; /* initial bucket */
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/* choose through intervening buckets */
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flocal = 0;
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do {
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collide = 0;
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retry_bucket = 0;
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r = rep;
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if (in->alg == CRUSH_BUCKET_UNIFORM) {
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/* be careful */
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if (firstn || numrep >= in->size)
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/* r' = r + f_total */
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r += ftotal;
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else if (in->size % numrep == 0)
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/* r'=r+(n+1)*f_local */
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r += (numrep+1) *
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(flocal+ftotal);
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else
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/* r' = r + n*f_local */
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r += numrep * (flocal+ftotal);
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} else {
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if (firstn)
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/* r' = r + f_total */
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r += ftotal;
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else
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/* r' = r + n*f_local */
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r += numrep * (flocal+ftotal);
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}
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/* bucket choose */
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if (in->size == 0) {
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reject = 1;
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goto reject;
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}
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if (flocal >= (in->size>>1) &&
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flocal > orig_tries)
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item = bucket_perm_choose(in, x, r);
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else
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item = crush_bucket_choose(in, x, r);
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BUG_ON(item >= map->max_devices);
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/* desired type? */
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if (item < 0)
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itemtype = map->buckets[-1-item]->type;
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else
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itemtype = 0;
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dprintk(" item %d type %d\n", item, itemtype);
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/* keep going? */
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if (itemtype != type) {
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BUG_ON(item >= 0 ||
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(-1-item) >= map->max_buckets);
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in = map->buckets[-1-item];
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retry_bucket = 1;
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continue;
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}
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/* collision? */
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for (i = 0; i < outpos; i++) {
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if (out[i] == item) {
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collide = 1;
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break;
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}
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}
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reject = 0;
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if (recurse_to_leaf) {
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if (item < 0) {
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if (crush_choose(map,
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map->buckets[-1-item],
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weight,
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x, outpos+1, 0,
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out2, outpos,
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firstn, 0,
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NULL) <= outpos)
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/* didn't get leaf */
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reject = 1;
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} else {
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/* we already have a leaf! */
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out2[outpos] = item;
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}
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}
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if (!reject) {
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/* out? */
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if (itemtype == 0)
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reject = is_out(map, weight,
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item, x);
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else
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reject = 0;
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}
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reject:
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if (reject || collide) {
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ftotal++;
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flocal++;
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if (collide && flocal < 3)
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/* retry locally a few times */
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retry_bucket = 1;
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else if (flocal < in->size + orig_tries)
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/* exhaustive bucket search */
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retry_bucket = 1;
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else if (ftotal < 20)
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/* then retry descent */
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retry_descent = 1;
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else
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/* else give up */
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skip_rep = 1;
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dprintk(" reject %d collide %d "
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"ftotal %d flocal %d\n",
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reject, collide, ftotal,
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flocal);
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}
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} while (retry_bucket);
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} while (retry_descent);
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if (skip_rep) {
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dprintk("skip rep\n");
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continue;
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}
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dprintk("CHOOSE got %d\n", item);
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out[outpos] = item;
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outpos++;
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}
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dprintk("CHOOSE returns %d\n", outpos);
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return outpos;
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}
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/**
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* crush_do_rule - calculate a mapping with the given input and rule
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* @map: the crush_map
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* @ruleno: the rule id
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* @x: hash input
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* @result: pointer to result vector
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* @result_max: maximum result size
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* @force: force initial replica choice; -1 for none
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*/
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int crush_do_rule(struct crush_map *map,
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int ruleno, int x, int *result, int result_max,
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int force, __u32 *weight)
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{
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int result_len;
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int force_context[CRUSH_MAX_DEPTH];
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int force_pos = -1;
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int a[CRUSH_MAX_SET];
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int b[CRUSH_MAX_SET];
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int c[CRUSH_MAX_SET];
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int recurse_to_leaf;
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int *w;
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int wsize = 0;
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int *o;
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int osize;
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int *tmp;
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struct crush_rule *rule;
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int step;
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int i, j;
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int numrep;
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int firstn;
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BUG_ON(ruleno >= map->max_rules);
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rule = map->rules[ruleno];
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result_len = 0;
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w = a;
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o = b;
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/*
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* determine hierarchical context of force, if any. note
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* that this may or may not correspond to the specific types
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* referenced by the crush rule.
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*/
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if (force >= 0 &&
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force < map->max_devices &&
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map->device_parents[force] != 0 &&
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!is_out(map, weight, force, x)) {
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while (1) {
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force_context[++force_pos] = force;
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if (force >= 0)
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force = map->device_parents[force];
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else
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force = map->bucket_parents[-1-force];
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if (force == 0)
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break;
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}
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}
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for (step = 0; step < rule->len; step++) {
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firstn = 0;
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switch (rule->steps[step].op) {
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case CRUSH_RULE_TAKE:
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w[0] = rule->steps[step].arg1;
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/* find position in force_context/hierarchy */
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while (force_pos >= 0 &&
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force_context[force_pos] != w[0])
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force_pos--;
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/* and move past it */
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if (force_pos >= 0)
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force_pos--;
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wsize = 1;
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break;
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case CRUSH_RULE_CHOOSE_LEAF_FIRSTN:
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case CRUSH_RULE_CHOOSE_FIRSTN:
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firstn = 1;
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case CRUSH_RULE_CHOOSE_LEAF_INDEP:
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case CRUSH_RULE_CHOOSE_INDEP:
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BUG_ON(wsize == 0);
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recurse_to_leaf =
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rule->steps[step].op ==
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CRUSH_RULE_CHOOSE_LEAF_FIRSTN ||
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rule->steps[step].op ==
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CRUSH_RULE_CHOOSE_LEAF_INDEP;
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/* reset output */
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osize = 0;
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for (i = 0; i < wsize; i++) {
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/*
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* see CRUSH_N, CRUSH_N_MINUS macros.
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* basically, numrep <= 0 means relative to
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* the provided result_max
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*/
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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);
|
|
}
|
|
}
|
|
return result_len;
|
|
}
|
|
|
|
|