linux-kernel - Re: Copy on write hard links?

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Date:	Wed, 25 Sep 2013 08:59:32 -0500
From:	Rob Landley <rob@...dley.net>
To:	Thomas Meyer <thomas@...3r.de>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Copy on write hard links?

On 09/24/2013 01:36:56 PM, Thomas Meyer wrote:
> Hi,
> 
> Is there such a thing?

In the kernel's vfs layer? No, although some filesystems (ala btrfs) do  
things like that with snapshots.

In userspace? Breaking hardlinks when updating a file is fairly normal,  
that's why they distinguish between "truncate and rewrite" (preserve  
hardlinks) and "write new file and rename over old file" (break  
hardlinks, avoiding the more obvious race conditions).

Rob--
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