FUSE（Bazil-Go）：如何执行MkDir请求？

I am trying to implement the function mkdir in a fuse, written in Go,and I'm using Bazil library. I have successfully implemented a simple read-only fs, and I now want to be able to call mkdir inside any existing directory to make a new one.

I have made sure that all the existing directories are writable,(attr.Mode = os.ModeDir | 0777). Right now I have just added the function:

func (d Dir) MkDir(ctx context.Context, req *fuse.MkdirRequest) (fs.Node, error) {
    dir := &Dir{name: req.Name, files: 0, inode: 10 /*a random inode*/,mode: os.FileMode(0777),nextdir: nil, nextfile: nil}
    d.nextdir = dir
    return dir, nil
}

in my own implementation of the hello fs example of Bazil's library. But that doesn't seem to make any difference.

When I call mkdir new_dir_name from the terminal, I get the error: "mkdir: cannot create directory ‘new_dir_name’: Operation not permitted", even though I have added the mkdir function.

Any insights as to why this is happening, and what else should I add to my code to make this working would be great. Also, this is my first stackoverflow question, so I'm sorry if I didn't ask in a clear way.