ceph: make CRUSH hash function a bucket property
Make the integer hash function a property of the bucket it is used on. This allows us to gracefully add support for new hash functions without starting from scatch. Signed-off-by: Sage Weil <sage@newdream.net>
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Sage Weil
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1654dd0cf5
commit
fb690390e3
@ -102,7 +102,8 @@ extern const char *crush_bucket_alg_name(int alg);
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struct crush_bucket {
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__s32 id; /* this'll be negative */
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__u16 type; /* non-zero; type=0 is reserved for devices */
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__u16 alg; /* one of CRUSH_BUCKET_* */
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__u8 alg; /* one of CRUSH_BUCKET_* */
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__u8 hash; /* which hash function to use, CRUSH_HASH_* */
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__u32 weight; /* 16-bit fixed point */
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__u32 size; /* num items */
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__s32 *items;
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@ -1,5 +1,6 @@
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#include <linux/types.h>
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#include "hash.h"
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/*
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* Robert Jenkins' function for mixing 32-bit values
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@ -20,7 +21,7 @@
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#define crush_hash_seed 1315423911
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__u32 crush_hash32(__u32 a)
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static __u32 crush_hash32_rjenkins1(__u32 a)
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{
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__u32 hash = crush_hash_seed ^ a;
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__u32 b = a;
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@ -31,7 +32,7 @@ __u32 crush_hash32(__u32 a)
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return hash;
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}
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__u32 crush_hash32_2(__u32 a, __u32 b)
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static __u32 crush_hash32_rjenkins1_2(__u32 a, __u32 b)
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{
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__u32 hash = crush_hash_seed ^ a ^ b;
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__u32 x = 231232;
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@ -42,7 +43,7 @@ __u32 crush_hash32_2(__u32 a, __u32 b)
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return hash;
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}
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__u32 crush_hash32_3(__u32 a, __u32 b, __u32 c)
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static __u32 crush_hash32_rjenkins1_3(__u32 a, __u32 b, __u32 c)
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{
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__u32 hash = crush_hash_seed ^ a ^ b ^ c;
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__u32 x = 231232;
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@ -55,7 +56,7 @@ __u32 crush_hash32_3(__u32 a, __u32 b, __u32 c)
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return hash;
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}
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__u32 crush_hash32_4(__u32 a, __u32 b, __u32 c, __u32 d)
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static __u32 crush_hash32_rjenkins1_4(__u32 a, __u32 b, __u32 c, __u32 d)
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{
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__u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d;
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__u32 x = 231232;
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@ -69,7 +70,8 @@ __u32 crush_hash32_4(__u32 a, __u32 b, __u32 c, __u32 d)
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return hash;
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}
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__u32 crush_hash32_5(__u32 a, __u32 b, __u32 c, __u32 d, __u32 e)
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static __u32 crush_hash32_rjenkins1_5(__u32 a, __u32 b, __u32 c, __u32 d,
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__u32 e)
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{
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__u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d ^ e;
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__u32 x = 231232;
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@ -84,3 +86,64 @@ __u32 crush_hash32_5(__u32 a, __u32 b, __u32 c, __u32 d, __u32 e)
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crush_hashmix(y, e, hash);
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return hash;
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}
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__u32 crush_hash32(int type, __u32 a)
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{
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switch (type) {
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case CRUSH_HASH_RJENKINS1:
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return crush_hash32_rjenkins1(a);
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default:
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return 0;
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}
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}
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__u32 crush_hash32_2(int type, __u32 a, __u32 b)
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{
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switch (type) {
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case CRUSH_HASH_RJENKINS1:
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return crush_hash32_rjenkins1_2(a, b);
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default:
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return 0;
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}
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}
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__u32 crush_hash32_3(int type, __u32 a, __u32 b, __u32 c)
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{
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switch (type) {
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case CRUSH_HASH_RJENKINS1:
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return crush_hash32_rjenkins1_3(a, b, c);
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default:
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return 0;
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}
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}
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__u32 crush_hash32_4(int type, __u32 a, __u32 b, __u32 c, __u32 d)
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{
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switch (type) {
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case CRUSH_HASH_RJENKINS1:
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return crush_hash32_rjenkins1_4(a, b, c, d);
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default:
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return 0;
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}
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}
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__u32 crush_hash32_5(int type, __u32 a, __u32 b, __u32 c, __u32 d, __u32 e)
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{
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switch (type) {
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case CRUSH_HASH_RJENKINS1:
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return crush_hash32_rjenkins1_5(a, b, c, d, e);
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default:
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return 0;
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}
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}
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const char *crush_hash_name(int type)
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{
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switch (type) {
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case CRUSH_HASH_RJENKINS1:
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return "rjenkins1";
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default:
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return "unknown";
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}
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}
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@ -1,12 +1,17 @@
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#ifndef _CRUSH_HASH_H
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#define _CRUSH_HASH_H
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extern __u32 crush_hash32(__u32 a);
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extern __u32 crush_hash32_2(__u32 a, __u32 b);
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extern __u32 crush_hash32_3(__u32 a, __u32 b, __u32 c);
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extern __u32 crush_hash32_4(__u32 a, __u32 b, __u32 c,
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__u32 d);
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extern __u32 crush_hash32_5(__u32 a, __u32 b, __u32 c,
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__u32 d, __u32 e);
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#define CRUSH_HASH_RJENKINS1 0
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#define CRUSH_HASH_DEFAULT CRUSH_HASH_RJENKINS1
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extern const char *crush_hash_name(int type);
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extern __u32 crush_hash32(int type, __u32 a);
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extern __u32 crush_hash32_2(int type, __u32 a, __u32 b);
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extern __u32 crush_hash32_3(int type, __u32 a, __u32 b, __u32 c);
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extern __u32 crush_hash32_4(int type, __u32 a, __u32 b, __u32 c, __u32 d);
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extern __u32 crush_hash32_5(int type, __u32 a, __u32 b, __u32 c, __u32 d,
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__u32 e);
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#endif
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@ -78,7 +78,7 @@ static int bucket_perm_choose(struct crush_bucket *bucket,
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/* optimize common r=0 case */
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if (pr == 0) {
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s = crush_hash32_3(x, bucket->id, 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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@ -103,7 +103,7 @@ static int bucket_perm_choose(struct crush_bucket *bucket,
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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(x, bucket->id, p) %
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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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@ -138,8 +138,8 @@ static int bucket_list_choose(struct crush_bucket_list *bucket,
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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(x, bucket->h.items[i], r,
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bucket->h.id);
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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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@ -198,7 +198,8 @@ static int bucket_tree_choose(struct crush_bucket_tree *bucket,
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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(x, n, r, bucket->h.id) * (__u64)w;
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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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@ -224,7 +225,7 @@ static int bucket_straw_choose(struct crush_bucket_straw *bucket,
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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(x, bucket->h.items[i], r);
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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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@ -267,7 +268,8 @@ static int is_out(struct crush_map *map, __u32 *weight, int item, int x)
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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(x, item) & 0xffff) < weight[item])
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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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@ -210,7 +210,8 @@ static struct crush_map *crush_decode(void *pbyval, void *end)
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ceph_decode_need(p, end, 4*sizeof(u32), bad);
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b->id = ceph_decode_32(p);
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b->type = ceph_decode_16(p);
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b->alg = ceph_decode_16(p);
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b->alg = ceph_decode_8(p);
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b->hash = ceph_decode_8(p);
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b->weight = ceph_decode_32(p);
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b->size = ceph_decode_32(p);
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