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45002267e8d2699bf9b022315bee3dd13b044843
linux-apfs/net/ceph/crush/mapper.c
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Ilya Dryomov 45002267e8 crush: ensuring at most num-rep osds are selected 
Crush temporary buffers are allocated as per replica size configured
by the user.  When there are more final osds (to be selected as per
rule) than the replicas, buffer overlaps and it causes crash.  Now, it
ensures that at most num-rep osds are selected even if more number of
osds are allowed by the rule.

Reflects ceph.git commits 6b4d1aa99718e3b367496326c1e64551330fabc0,
                          234b066ba04976783d15ff2abc3e81b6cc06fb10.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
2015-04-22 18:33:42 +03:00

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#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 <linux/crush/crush.h>
#include <linux/crush/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(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];
}
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);
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)
* @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,
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\n",
recurse_to_leaf ? "_LEAF" : "",
bucket->id, x, outpos, numrep,
tries, recurse_tries, local_retries, local_fallback_retries,
parent_r);
for (rep = 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, outpos+1, 0,
out2, outpos, count,
recurse_tries, 0,
local_retries,
local_fallback_retries,
0,
vary_r,
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--;
}
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++) {
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;
}
}
}
/**
* 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;
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:
w[0] = curstep->arg1;
wsize = 1;
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_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++) {
/*
* 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;
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[-1-w[i]],
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,
c+osize,
0);
} else {
out_size = ((numrep < (result_max-osize)) ?
numrep : (result_max-osize));
crush_choose_indep(
map,
map->buckets[-1-w[i]],
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;
}
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