Fix Block::_disk_file_size
Fix Block::_disk_file_size

lylei/dfs,linyvxiang/dfs,bluebore/bfs,myawan/bfs-1,baidu/bfs,lylei/dfs,myawan/bfs-1,bluebore/bfs,imotai/bfs,yvxiang/dfs,baidu/bfs,imotai/bfs,bluebore/bfs,bluebore/dfs,baidu/bfs,myawan/bfs-1,bluebore/dfs,linyvxiang/dfs,yvxiang/coverage_for_bfs,yvxiang/dfs,baidu/bfs,linyvxiang/dfs,00k/ToyDFS,myawan/bfs-1,yvxiang/coverage_for_bfs,00k/ToyDFS,lylei/dfs,imotai/bfs,bluebore/dfs,yvxiang/dfs,yvxiang/coverage_for_bfs,yvxiang/dfs,lylei/dfs,yvxiang/coverage_for_bfs