rem: Unset(); fBlockNumber = block; return fBlock = empty ? (uint8 *)get_empty_block(fVolume->Device(), block, BlockSize()) : (uint8 *)get_block(fVolume->Device(), block, BlockSize());
add: return SetTo(fVolume->ToBlock(run), empty);
context: CachedBlock::SetTo(off_t block, bool empty){	Unset();	fBlockNumber = block;	return fBlock = empty ? (uint8 *)get_empty_block(fVolume->Device(), block, BlockSize())						  : (uint8 *)get_block(fVolume->Device(), block, BlockSize());}