1 files changed, 90 insertions, 0 deletions

diff --git a/fs/ceph/crush/hash.h b/fs/ceph/crush/hash.h
new file mode 100644
index 000000000000..42f3312783a1
--- /dev/null
+++ b/fs/ceph/crush/hash.h
@@ -0,0 +1,90 @@
+#ifndef _CRUSH_HASH_H
+#define _CRUSH_HASH_H
+
+/*
+ * Robert Jenkins' function for mixing 32-bit values
+ * http://burtleburtle.net/bob/hash/evahash.html
+ * a, b = random bits, c = input and output
+ */
+#define crush_hashmix(a, b, c) do {                     \
+                a = a-b;  a = a-c;  a = a^(c>>13);      \
+                b = b-c;  b = b-a;  b = b^(a<<8);       \
+                c = c-a;  c = c-b;  c = c^(b>>13);      \
+                a = a-b;  a = a-c;  a = a^(c>>12);      \
+                b = b-c;  b = b-a;  b = b^(a<<16);      \
+                c = c-a;  c = c-b;  c = c^(b>>5);       \
+                a = a-b;  a = a-c;  a = a^(c>>3);       \
+                b = b-c;  b = b-a;  b = b^(a<<10);      \
+                c = c-a;  c = c-b;  c = c^(b>>15);      \
+        } while (0)
+
+#define crush_hash_seed 1315423911
+
+static inline __u32 crush_hash32(__u32 a)
+{
+        __u32 hash = crush_hash_seed ^ a;
+        __u32 b = a;
+        __u32 x = 231232;
+        __u32 y = 1232;
+        crush_hashmix(b, x, hash);
+        crush_hashmix(y, a, hash);
+        return hash;
+}
+
+static inline __u32 crush_hash32_2(__u32 a, __u32 b)
+{
+        __u32 hash = crush_hash_seed ^ a ^ b;
+        __u32 x = 231232;
+        __u32 y = 1232;
+        crush_hashmix(a, b, hash);
+        crush_hashmix(x, a, hash);
+        crush_hashmix(b, y, hash);
+        return hash;
+}
+
+static inline __u32 crush_hash32_3(__u32 a, __u32 b, __u32 c)
+{
+        __u32 hash = crush_hash_seed ^ a ^ b ^ c;
+        __u32 x = 231232;
+        __u32 y = 1232;
+        crush_hashmix(a, b, hash);
+        crush_hashmix(c, x, hash);
+        crush_hashmix(y, a, hash);
+        crush_hashmix(b, x, hash);
+        crush_hashmix(y, c, hash);
+        return hash;
+}
+
+static inline __u32 crush_hash32_4(__u32 a, __u32 b, __u32 c,
+                                   __u32 d)
+{
+        __u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d;
+        __u32 x = 231232;
+        __u32 y = 1232;
+        crush_hashmix(a, b, hash);
+        crush_hashmix(c, d, hash);
+        crush_hashmix(a, x, hash);
+        crush_hashmix(y, b, hash);
+        crush_hashmix(c, x, hash);
+        crush_hashmix(y, d, hash);
+        return hash;
+}
+
+static inline __u32 crush_hash32_5(__u32 a, __u32 b, __u32 c,
+                                   __u32 d, __u32 e)
+{
+        __u32 hash = crush_hash_seed ^ a ^ b ^ c ^ d ^ e;
+        __u32 x = 231232;
+        __u32 y = 1232;
+        crush_hashmix(a, b, hash);
+        crush_hashmix(c, d, hash);
+        crush_hashmix(e, x, hash);
+        crush_hashmix(y, a, hash);
+        crush_hashmix(b, x, hash);
+        crush_hashmix(y, c, hash);
+        crush_hashmix(d, x, hash);
+        crush_hashmix(y, e, hash);
+        return hash;
+}
+
+#endif