rem: DeviceOpener::InitCache(off_t numBlocks)
add: DeviceOpener::InitCache(off_t numBlocks, uint32 blockSize)
context: DeviceOpener::InitCache(off_t numBlocks){	if (init_cache_for_device(fDevice, numBlocks) == B_OK) {		fCached = true;		return B_OK;	}	return B_ERROR;}