/* perform lookup in backing fs. */
#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0))
rc = cache_dir->i_op->lookup(cache_dir, cache_dentry);
/* perform lookup in backing fs. */
#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0))
rc = cache_dir->i_op->lookup(cache_dir, cache_dentry);