rem: block->updated = NULL;
add: block->original = NULL; #ifdef DEBUG_CHANGED block->compare = NULL; #endif
context: new_cached_block(block_cache *cache, off_t blockNumber, bool cleared = false){	cached_block *block = (cached_block *)malloc(sizeof(cached_block));	if (block == NULL)		return NULL;	if (!cleared) {		block->data = malloc(cache->block_size);		if (block->data == NULL) {			free(block);			return NULL;		}	} else		block->data = NULL;	block->block_number = blockNumber;	block->lock = 0;	block->transaction_next = NULL;	block->transaction = block->previous_transaction = NULL;	block->updated = NULL;	hash_insert(cache->hash, block);	return block;}