crush_hash32_4
extern __u32 crush_hash32_4(int type, __u32 a, __u32 b, __u32 c, __u32 d);
__u64 w = crush_hash32_4(bucket->h.hash, x, bucket->h.items[i],
t = (__u64)crush_hash32_4(bucket->h.hash, x, n, r,