From: Dave Chinner <david@fromorbit.com>
To: "Pádraig Brady" <P@draigBrady.com>
Cc: "Frank A. Kingswood" <frank@kingswood-consulting.co.uk>,
linux-kernel@vger.kernel.org
Subject: Re: atomically swap two files
Date: Sat, 27 Nov 2010 01:19:11 +1100 [thread overview]
Message-ID: <20101126141911.GJ12187@dastard> (raw)
In-Reply-To: <4CEF9E68.9080200@draigBrady.com>
On Fri, Nov 26, 2010 at 11:47:52AM +0000, Pádraig Brady wrote:
> On 25/11/10 20:11, Frank A. Kingswood wrote:
> > Hi!
> >
> > Is it possible to swap two files in an atomic way, so that after the
> > syscall either the two files have exchanged names or neither has been
> > modified?
> >
> > I suspect that btrfs could do it, but I'm wondering about ext3/4.
>
> I don't think there is anything equivalent to exchangedata() on Linux
> http://developer.apple.com/library/mac/#DOCUMENTATION/Darwin/Reference/ManPages/man2/exchangedata.2.html
XFS can do that, though the interface is an ioctl (XFS_IOC_SWAPEXT)
whose parameters are closely tied to the functionality of the only
user: the online defragmenter (xfs_fsr). It would be pretty easy to
wire it up to such a syscall if one existed, though....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
prev parent reply other threads:[~2010-11-26 14:19 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-25 20:11 atomically swap two files Frank A. Kingswood
2010-11-26 11:47 ` Pádraig Brady
2010-11-26 14:19 ` Dave Chinner [this message]
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