SUNRPC: Make the credential cache hashtable size configurable

This patch allows the user to configure the credential cache hashtable size
using a new module parameter: auth_hashtable_size
When set, this parameter will be rounded up to the nearest power of two,
with a maximum allowed value of 1024 elements.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/sunrpc/auth.h b/include/linux/sunrpc/auth.h
index 84d64b6..d273762 100644
--- a/include/linux/sunrpc/auth.h
+++ b/include/linux/sunrpc/auth.h
@@ -61,14 +61,7 @@
 /*
  * Client authentication handle
  */
-#define RPC_CREDCACHE_HASHBITS	4
-#define RPC_CREDCACHE_NR	(1 << RPC_CREDCACHE_HASHBITS)
-struct rpc_cred_cache {
-	struct hlist_head	hashtable[RPC_CREDCACHE_NR];
-	unsigned int		hashbits;
-	spinlock_t		lock;
-};
-
+struct rpc_cred_cache;
 struct rpc_authops;
 struct rpc_auth {
 	unsigned int		au_cslack;	/* call cred size estimate */