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>

1 files changed, 68 insertions, 5 deletions

diff --git a/fs/ceph/crush/hash.c b/fs/ceph/crush/hash.c
index b438c5d27816..5873aed694bf 100644
--- 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";
+        }
+}