Re: [PATCH v2 10/11] fhandle, pidfs: support open_by_handle_at() purely based on file handle

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

On Tue, Jun 24, 2025 at 10:29:13AM +0200, Christian Brauner wrote:
> Various filesystems such as pidfs (and likely drm in the future) have a
> use-case to support opening files purely based on the handle without
> having to require a file descriptor to another object. That's especially
> the case for filesystems that don't do any lookup whatsoever and there's
> zero relationship between the objects. Such filesystems are also
> singletons that stay around for the lifetime of the system meaning that
> they can be uniquely identified and accessed purely based on the file
> handle type. Enable that so that userspace doesn't have to allocate an
> object needlessly especially if they can't do that for whatever reason.

Whoa...  Two notes:
	1) you really want to make sure that no _directories_ on those
filesystems are decodable.
	2) do you want to get the damn things bound somewhere?