issue0027 Fix Write Permission

1.root can write anywhere even he has no w permission
2.other user can write on the path the has permission

tower: https://tower.im/projects/26b692e17d9943c4b62c8045c8410529/todos/da1a14dc49424d759ab8fee44f0eff5f/

Change-Id: I2250f15388edbe42946c66d460beabe7b0ea6b05