#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;
}
