555970 - missing read lock in the combination of cos and nsview

https://bugzilla.redhat.com/show_bug.cgi?id=555970

Description: view read lock was missing in a view api called from
COS.

ldap/servers/plugins/views/views.c

@@ -306,6 +306,9 @@ static int _internal_api_views_entry_exists_general(char *view_dn, Slapi_Entry *
 	 * view filter - either match will do
 	 */
 
+	/* Read lock the cache */
+	views_read_lock();
+
 	/* find the view */
 	view = views_cache_find_view(view_dn);
 	if(0==view)
@@ -348,6 +351,7 @@ static int _internal_api_views_entry_exists_general(char *view_dn, Slapi_Entry *
 	}
 
 bail:
+	views_unlock();
 	return ret;
 }