Re: [PATCH 09/19] pramfs: inode operations for dirs

[Al Viro <viro@ZenIV.linux.org.uk>]

On Sat, Sep 07, 2013 at 10:23:42AM +0200, Marco Stornelli wrote:

> +static int pram_rmdir(struct inode *dir, struct dentry *dentry)
> +{
> +	struct inode *inode = dentry->d_inode;
> +	struct pram_inode *pi;
> +	int err = -ENOTEMPTY;
> +
> +	if (!inode)
> +		return -ENOENT;
> +
> +	pi = pram_get_inode(dir->i_sb, inode->i_ino);
> +
> +	/* directory to delete is empty? */
> +	if (pi->i_type.dir.tail == 0) {
> +		inode->i_ctime = dir->i_ctime;
> +		inode->i_size = 0;
> +		clear_nlink(inode);
> +		pram_write_inode(inode, NULL);
> +		pram_dec_count(dir);
> +		err = 0;
> +	} else {
> +		pram_dbg("dir not empty\n");
> +	}
> +
> +	return err;
> +}

... and here you are paying for delayed removal of entries:
	mkdir foo
	touch foo/bar
	rm -rf foo <foo/bar
will fail, since opened-and-unlinked file in effect keeps the directory
where it used to be "not empty" from your rmdir (and rename) POV.