linux-kernel - Re: [RFC] readlink()-related oddities

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Date:	Fri, 20 Nov 2015 10:00:41 +0000
From:	David Howells <dhowells@...hat.com>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	dhowells@...hat.com,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	LSM List <linux-security-module@...r.kernel.org>,
	Miklos Szeredi <miklos@...redi.hu>
Subject: Re: [RFC] readlink()-related oddities

Al Viro <viro@...IV.linux.org.uk> wrote:

> How would those tools know that this particular pathname _is_ a magical
> symlink?  Sure, if you see a symlink with body that starts with % or #,
> you could figure out that it's not a regular one and go parse the body,
> but for stat(2) it looks like a directory.  Do those tools call readlink()
> on every directory they spot on AFS volume?  David?

It has to be a directory so that you can mount on it.  If you look in /afs on
an OpenAFS client filesystem it appears as a symlink to somewhere under /afs/
because they can't do the in-kernel mounting (it's GPL-only on Linux).

David
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