selinux: increase avtab max buckets

Now that we can safely increase the avtab max buckets without
triggering high order allocations and have a hash function that
will make better use of the larger number of buckets, increase
the max buckets to 2^16.

Original:
101421 entries and 2048/2048 buckets used, longest chain length 374

With new hash function:
101421 entries and 2048/2048 buckets used, longest chain length 81

With increased max buckets:
101421 entries and 31078/32768 buckets used, longest chain length 12
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <pmoore@redhat.com>

security/selinux/ss/avtab.h

@@ -86,7 +86,7 @@ struct avtab_node *avtab_search_node_next(struct avtab_node *node, int specified
 void avtab_cache_init(void);
 void avtab_cache_destroy(void);
 
-#define MAX_AVTAB_HASH_BITS 11
+#define MAX_AVTAB_HASH_BITS 16
 #define MAX_AVTAB_HASH_BUCKETS (1 << MAX_AVTAB_HASH_BITS)
 
 #endif	/* _SS_AVTAB_H_ */