linux-kernel - Re: RFC: permit link(2) to work across --bind mounts ?

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Date:	Wed, 19 Dec 2007 11:47:02 -0500
From:	Mark Lord <lkml@....ca>
To:	David Newall <david@...idnewall.com>
Cc:	Al Viro <viro@....linux.org.uk>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: RFC: permit link(2)  to work across --bind mounts ?

David Newall wrote:
> Mark Lord wrote:
>> But.. pity there's no mount flag override for smaller systems,
>> where bind mounts might be more useful with link(2) actually working.
> 
> I don't see it.  You always can make hard link on the underlying 
> filesystem.  If you need to make it on the bound mount, that is, if you 
> can't locate the underlying filesystem to make the hard link, you can 
> use a symbolic link.
..

Where people run into trouble with this, is when they simply go to
move a huge file (DVD image) from one directory to another,
where the target happens to be on a different bind point of the
same underlying filesystem.

This can happen in a variety of common ways, including accessing
over CIFS or Samba.

And the result is a very very long delay while we copy 4-8GB of data
instead of simply moving the link.

Cheers
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