nfsd4: better stateid hashing

First, we shouldn't care here about the structure of the opaque part of
the stateid.  Second, this hash is really dumb.  (I'm not sure the
replacement is much better, though--to look at it another patch.)
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -168,9 +168,9 @@ static unsigned int file_hashval(struct inode *ino)
 	return hash_ptr(ino, FILE_HASH_BITS);
 }
 
-static unsigned int stateid_hashval(u32 owner_id, u32 file_id)
+static unsigned int stateid_hashval(stateid_t *s)
 {
-	return (owner_id + file_id) & STATEID_HASH_MASK;
+	return opaque_hashval(&s->si_opaque, sizeof(stateid_opaque_t)) & STATEID_HASH_MASK;
 }
 
 static struct list_head file_hashtbl[FILE_HASH_SIZE];
@@ -221,7 +221,7 @@ static inline void hash_stid(struct nfs4_stid *stid)
 	stateid_t *s = &stid->sc_stateid;
 	unsigned int hashval;
 
-	hashval = stateid_hashval(s->si_stateownerid, s->si_fileid);
+	hashval = stateid_hashval(s);
 	list_add(&stid->sc_hash, &stateid_hashtbl[hashval]);
 }
 
@@ -1083,7 +1083,7 @@ static struct nfs4_stid *find_stateid(stateid_t *t)
 	struct nfs4_stid *s;
 	unsigned int hashval;
 
-	hashval = stateid_hashval(t->si_stateownerid, t->si_fileid);
+	hashval = stateid_hashval(t);
 	list_for_each_entry(s, &stateid_hashtbl[hashval], sc_hash)
 		if (same_stateid(&s->sc_stateid, t))
 			return s;