BugFix: block resource leak
BugFix: block resource leak

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