I_MUTEX_CHILD
inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
inode_lock_nested(inode, I_MUTEX_CHILD);
inode_lock_nested(inode, I_MUTEX_CHILD);
inode_lock_nested(source, I_MUTEX_CHILD);
inode_lock_nested(target, I_MUTEX_CHILD);
inode_lock_nested(new_inode, I_MUTEX_CHILD);