b=15962 statahead should not alias dentry with inode, which should be done by VFS...

b=15962 statahead should not alias dentry with inode, which should be done by VFS layer operation with parent dir's i_mutex held

1) statahead should not alias dentry with inode, which should be done by VFS layer operation with parent dir's i_mutex held
2) code cleanup

i=tom.wang
i=jinshan.xiong