code: func (fs *Goofys) insertInode(parent *Inode, inode *Inode) {
  	inode.Id = fs.allocateInodeId()
  	parent.insertChildUnlocked(inode)
  	fs.inodes[inode.Id] = inode
  }
docs: // LOCKS_REQUIRED(fs.mu)
  // LOCKS_REQUIRED(parent.mu)