Re: [PATCH RFC 0/1] mount: universally disallow mounting over symlinks

[Al Viro]

On Tue, Jan 14, 2020 at 08:25:19AM +0800, Ian Kent wrote:

> This isn't right.
> 
> There's actually nothing stopping a user from using a direct map
> entry that's a multi-mount without an actual mount at its root.
> So there could be directories created under these, it's just not
> usually done.
> 
> I'm pretty sure I don't check and disallow this.

IDGI...  How the hell will that work in v5?  Who will set _any_
traps outside the one in root in that scenario?  autofs_lookup()
won't (there it's conditional upon indirect mount).  Neither
will autofs_dir_mkdir() (conditional upon version being less
than 5).  Who will, then?

Confused...