NFSD: De-duplicate hash bucket indexing

Clean up: The details of finding the right hash bucket are exactly
the same in both nfsd_cache_lookup() and nfsd_cache_update().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfscache.c

@@ -84,12 +84,6 @@ nfsd_hashsize(unsigned int limit)
 	return roundup_pow_of_two(limit / TARGET_BUCKET_SIZE);
 }
 
-static u32
-nfsd_cache_hash(__be32 xid, struct nfsd_net *nn)
-{
-	return hash_32((__force u32)xid, nn->maskbits);
-}
-
 static struct svc_cacherep *
 nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum,
 			struct nfsd_net *nn)
@@ -241,6 +235,14 @@ lru_put_end(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
 	list_move_tail(&rp->c_lru, &b->lru_head);
 }
 
+static noinline struct nfsd_drc_bucket *
+nfsd_cache_bucket_find(__be32 xid, struct nfsd_net *nn)
+{
+	unsigned int hash = hash_32((__force u32)xid, nn->maskbits);
+
+	return &nn->drc_hashtbl[hash];
+}
+
 static long prune_bucket(struct nfsd_drc_bucket *b, struct nfsd_net *nn,
 			 unsigned int max)
 {
@@ -421,10 +423,8 @@ int nfsd_cache_lookup(struct svc_rqst *rqstp)
 {
 	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
 	struct svc_cacherep	*rp, *found;
-	__be32			xid = rqstp->rq_xid;
 	__wsum			csum;
-	u32 hash = nfsd_cache_hash(xid, nn);
-	struct nfsd_drc_bucket *b = &nn->drc_hashtbl[hash];
+	struct nfsd_drc_bucket	*b = nfsd_cache_bucket_find(rqstp->rq_xid, nn);
 	int type = rqstp->rq_cachetype;
 	int rtn = RC_DOIT;
 
@@ -528,7 +528,6 @@ void nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)
 	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
 	struct svc_cacherep *rp = rqstp->rq_cacherep;
 	struct kvec	*resv = &rqstp->rq_res.head[0], *cachv;
-	u32		hash;
 	struct nfsd_drc_bucket *b;
 	int		len;
 	size_t		bufsize = 0;
@@ -536,8 +535,7 @@ void nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)
 	if (!rp)
 		return;
 
-	hash = nfsd_cache_hash(rp->c_key.k_xid, nn);
-	b = &nn->drc_hashtbl[hash];
+	b = nfsd_cache_bucket_find(rp->c_key.k_xid, nn);
 
 	len = resv->iov_len - ((char*)statp - (char*)resv->iov_base);
 	len >>= 2;