On Wed 15-05-19 01:18:58, Amir Goldstein wrote:
> There is a common pattern among pseudo filesystems for removing a dentry
> from code paths that are NOT coming from vfs_{unlink,rmdir}, using a
> combination of simple_{unlink,rmdir} and d_delete().
>
> Create an helper to perform this common operation. This helper is going
> to be used as a place holder for the new fsnotify_remove() hook.
>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Looks like a good idea. One comment below:
> +/*
> + * Unlike simple_unlink/rmdir, this helper is NOT called from vfs_unlink/rmdir.
> + * Caller must guaranty that d_parent and d_name are stable.
> + */
> +int simple_remove(struct inode *dir, struct dentry *dentry)
> +{
> + int ret;
> +
> + dget(dentry);
> + if (d_is_dir(dentry))
> + ret = simple_rmdir(dir, dentry);
> + else
> + ret = simple_unlink(dir, dentry);
> +
> + if (!ret)
> + d_delete(dentry);
> + dput(dentry);
This dget() - dput() pair looks fishy. After some research I understand why
it's needed but I think it deserves a comment like:
/*
* 'simple_' operations get dentry reference on create/mkdir and drop
* it on unlink/rmdir. So we have to get dentry reference here to
* protect d_delete() from accessing freed dentry.
*/
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
