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>

diff --git a/fs/ceph/crush/crush.h b/fs/ceph/crush/crush.h
index 92c6b3c3a5711c32c16659378c3d00318a1ac225..dcd7e752370077cd6cbba5745a0249667e04e73e 100644 (file)
--- a/fs/ceph/crush/crush.h
+++ b/fs/ceph/crush/crush.h
@@ -102,7 +102,8 @@ extern const char *crush_bucket_alg_name(int alg);
 struct crush_bucket {
        __s32 id;        /* this'll be negative */
        __u16 type;      /* non-zero; type=0 is reserved for devices */
-       __u16 alg;       /* one of CRUSH_BUCKET_* */
+       __u8 alg;        /* one of CRUSH_BUCKET_* */
+       __u8 hash;       /* which hash function to use, CRUSH_HASH_* */
        __u32 weight;    /* 16-bit fixed point */
        __u32 size;      /* num items */
        __s32 *items;

diff --git a/fs/ceph/crush/hash.c b/fs/ceph/crush/hash.c
index b438c5d278161b9fa20cc0b6d7622c0dd2476188..5873aed694bf5a06a092102a2209c5ad71a9aff8 100644 (file)
--- a/fs/ceph/crush/hash.c
+++ b/fs/ceph/crush/hash.c
@@ -1,5 +1,6 @@
 
 #include <linux/types.h>
+#include "hash.h"
 
 /*
  * Robert Jenkins' function for mixing 32-bit values
@@ -20,7 +21,7 @@
 
 #define crush_hash_seed 1315423911
 
-__u32 crush_hash32(__u32 a)
+static __u32 crush_hash32_rjenkins1(__u32 a)
 {
        __u32 hash = crush_hash_seed ^ a;
        __u32 b = a;
@@ -31,7 +32,7 @@ __u32 crush_hash32(__u32 a)
        return hash;
 }
 
-__u32 crush_hash32_2(__u32 a, __u32 b)
+static __u32 crush_hash32_rjenkins1_2(__u32 a, __u32 b)
 {
        __u32 hash = crush_hash_seed ^ a ^ b;
        __u32 x = 231232;
@@ -42,7 +43,7 @@ __u32 crush_hash32_2(__u32 a, __u32 b)
        return hash;
 }
 
-__u32 crush_hash32_3(__u32 a, __u32 b, __u32 c)
+static __u32 crush_hash32_rjenkins1_3(__u32 a, __u32 b, __u32 c)
 {
        __u32 hash = crush_hash_seed ^ a ^ b ^ c;
        __u32 x = 231232;
@@ -55,7 +56,7 @@ __u32 crush_hash32_3(__u32 a, __u32 b, __u32 c)
        return hash;
 }
 
-__u32 crush_hash32_4(__u32 a, __u32 b, __u32 c, __u32 d)
+static __u32 crush_hash32_rjenkins1_4(__u32 a, __u32 b, __u32 c, __u32 d)
 {
        __u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d;
        __u32 x = 231232;
@@ -69,7 +70,8 @@ __u32 crush_hash32_4(__u32 a, __u32 b, __u32 c, __u32 d)
        return hash;
 }
 
-__u32 crush_hash32_5(__u32 a, __u32 b, __u32 c, __u32 d, __u32 e)
+static __u32 crush_hash32_rjenkins1_5(__u32 a, __u32 b, __u32 c, __u32 d,
+                                     __u32 e)
 {
        __u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d ^ e;
        __u32 x = 231232;
@@ -84,3 +86,64 @@ __u32 crush_hash32_5(__u32 a, __u32 b, __u32 c, __u32 d, __u32 e)
        crush_hashmix(y, e, hash);
        return hash;
 }
+
+
+__u32 crush_hash32(int type, __u32 a)
+{
+       switch (type) {
+       case CRUSH_HASH_RJENKINS1:
+               return crush_hash32_rjenkins1(a);
+       default:
+               return 0;
+       }
+}
+
+__u32 crush_hash32_2(int type, __u32 a, __u32 b)
+{
+       switch (type) {
+       case CRUSH_HASH_RJENKINS1:
+               return crush_hash32_rjenkins1_2(a, b);
+       default:
+               return 0;
+       }
+}
+
+__u32 crush_hash32_3(int type, __u32 a, __u32 b, __u32 c)
+{
+       switch (type) {
+       case CRUSH_HASH_RJENKINS1:
+               return crush_hash32_rjenkins1_3(a, b, c);
+       default:
+               return 0;
+       }
+}
+
+__u32 crush_hash32_4(int type, __u32 a, __u32 b, __u32 c, __u32 d)
+{
+       switch (type) {
+       case CRUSH_HASH_RJENKINS1:
+               return crush_hash32_rjenkins1_4(a, b, c, d);
+       default:
+               return 0;
+       }
+}
+
+__u32 crush_hash32_5(int type, __u32 a, __u32 b, __u32 c, __u32 d, __u32 e)
+{
+       switch (type) {
+       case CRUSH_HASH_RJENKINS1:
+               return crush_hash32_rjenkins1_5(a, b, c, d, e);
+       default:
+               return 0;
+       }
+}
+
+const char *crush_hash_name(int type)
+{
+       switch (type) {
+       case CRUSH_HASH_RJENKINS1:
+               return "rjenkins1";
+       default:
+               return "unknown";
+       }
+}

diff --git a/fs/ceph/crush/hash.h b/fs/ceph/crush/hash.h
index 9ce89f85dc7d70342b44314164f924fd31a89901..ff48e110e4bb44232102363a93809eaf4e793178 100644 (file)
--- a/fs/ceph/crush/hash.h
+++ b/fs/ceph/crush/hash.h
@@ -1,12 +1,17 @@
 #ifndef _CRUSH_HASH_H
 #define _CRUSH_HASH_H
 
-extern __u32 crush_hash32(__u32 a);
-extern __u32 crush_hash32_2(__u32 a, __u32 b);
-extern __u32 crush_hash32_3(__u32 a, __u32 b, __u32 c);
-extern __u32 crush_hash32_4(__u32 a, __u32 b, __u32 c,
-                           __u32 d);
-extern __u32 crush_hash32_5(__u32 a, __u32 b, __u32 c,
-                           __u32 d, __u32 e);
+#define CRUSH_HASH_RJENKINS1   0
+
+#define CRUSH_HASH_DEFAULT CRUSH_HASH_RJENKINS1
+
+extern const char *crush_hash_name(int type);
+
+extern __u32 crush_hash32(int type, __u32 a);
+extern __u32 crush_hash32_2(int type, __u32 a, __u32 b);
+extern __u32 crush_hash32_3(int type, __u32 a, __u32 b, __u32 c);
+extern __u32 crush_hash32_4(int type, __u32 a, __u32 b, __u32 c, __u32 d);
+extern __u32 crush_hash32_5(int type, __u32 a, __u32 b, __u32 c, __u32 d,
+                           __u32 e);
 
 #endif

diff --git a/fs/ceph/crush/mapper.c b/fs/ceph/crush/mapper.c
index 54f3f402af60b4865e6c8b0d25b16efb6efc55bd..2523d448445c11e53c061fc1582842bdb08d9c25 100644 (file)
--- a/fs/ceph/crush/mapper.c
+++ b/fs/ceph/crush/mapper.c
@@ -78,7 +78,7 @@ static int bucket_perm_choose(struct crush_bucket *bucket,
 
                /* optimize common r=0 case */
                if (pr == 0) {
-                       s = crush_hash32_3(x, bucket->id, 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 */
@@ -103,7 +103,7 @@ static int bucket_perm_choose(struct crush_bucket *bucket,
                unsigned p = bucket->perm_n;
                /* no point in swapping the final entry */
                if (p < bucket->size - 1) {
-                       i = crush_hash32_3(x, bucket->id, p) %
+                       i = crush_hash32_3(bucket->hash, x, bucket->id, p) %
                                (bucket->size - p);
                        if (i) {
                                unsigned t = bucket->perm[p + i];
@@ -138,8 +138,8 @@ static int bucket_list_choose(struct crush_bucket_list *bucket,
        int i;
 
        for (i = bucket->h.size-1; i >= 0; i--) {
-               __u64 w = crush_hash32_4(x, bucket->h.items[i], r,
-                                        bucket->h.id);
+               __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",
@@ -198,7 +198,8 @@ static int bucket_tree_choose(struct crush_bucket_tree *bucket,
        while (!terminal(n)) {
                /* pick point in [0, w) */
                w = bucket->node_weights[n];
-               t = (__u64)crush_hash32_4(x, n, r, bucket->h.id) * (__u64)w;
+               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? */
@@ -224,7 +225,7 @@ static int bucket_straw_choose(struct crush_bucket_straw *bucket,
        __u64 draw;
 
        for (i = 0; i < bucket->h.size; i++) {
-               draw = crush_hash32_3(x, bucket->h.items[i], r);
+               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) {
@@ -267,7 +268,8 @@ static int is_out(struct crush_map *map, __u32 *weight, int item, int x)
                return 0;
        if (weight[item] == 0)
                return 1;
-       if ((crush_hash32_2(x, item) & 0xffff) < weight[item])
+       if ((crush_hash32_2(CRUSH_HASH_RJENKINS1, x, item) & 0xffff)
+           < weight[item])
                return 0;
        return 1;
 }

diff --git a/fs/ceph/osdmap.c b/fs/ceph/osdmap.c
index 68478270ad708f33c33ace72af86baad5e4b70bc..8c994c714781ea8dd8521b37933cb57fe21fd50a 100644 (file)
--- a/fs/ceph/osdmap.c
+++ b/fs/ceph/osdmap.c
@@ -210,7 +210,8 @@ static struct crush_map *crush_decode(void *pbyval, void *end)
                ceph_decode_need(p, end, 4*sizeof(u32), bad);
                b->id = ceph_decode_32(p);
                b->type = ceph_decode_16(p);
-               b->alg = ceph_decode_16(p);
+               b->alg = ceph_decode_8(p);
+               b->hash = ceph_decode_8(p);
                b->weight = ceph_decode_32(p);
                b->size = ceph_decode_32(p);