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Date: Sat, 22 Jul 2006 11:13:01 -0700
From: "Joshua Hudson" <joshudson@gmail.com>
To: linux-kernel@vger.kernel.org
Subject: Re: what is necessary for directory hard links
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On 7/22/06, Bodo Eggert <7eggert@elstempel.de> wrote:
> Horst H. von Brand <vonbrand@inf.utfsm.cl> wrote:
>
> > Joshua Hudson <joshudson@gmail.com> wrote:
> >> This patch is the sum total of all that I had to change in the kernel
> >> VFS layer to support hard links to directories
> >
> > Can't be done, as it creates the possibility of loops.
>
> Don't do that then?
Exactly.

> > Detecting unconnected subgraphs uses a /lot/ of memory; and much worse, you
> > have to stop (almost) all filesystem activity while doing it.
I know.

I just decided the price is worth it.

In my filesystem, any attempt to create a loop of hard links
is detected and cancelled. Unlinking a directory requires it
to be empty if the last link is being removed. "." and ".."
links are counted separately from real links, so that is easy.