From: Dave Chinner <david@fromorbit.com>
To: Ted Ts'o <tytso@mit.edu>
Cc: Thomas Lindroth <thomas.lindroth@gmail.com>, linux-ext4@vger.kernel.org
Subject: Re: e4defrag modifies folder's mtime.
Date: Wed, 4 Jan 2012 15:53:18 +1100 [thread overview]
Message-ID: <20120104045318.GA17026@dastard> (raw)
In-Reply-To: <20120103203443.GC30502@thunk.org>
On Tue, Jan 03, 2012 at 03:34:43PM -0500, Ted Ts'o wrote:
> On Sun, Jan 01, 2012 at 09:12:36PM +0100, Thomas Lindroth wrote:
> > I ran e4defrag from e2fsprogs-1.42 on a file system and a lot of
> > folders had their mtime updated as a result. This confuses both my
> > backup program and myself. I guess the folder timestamps change
> > because the temporary donor file is created in the same directory as
> > the original file. XFS's defrag program put the donor files in a
> > temporary folder in the root of the file system. Maybe e4defrag
> > could do the same.
>
> Yes, that could be done if the user running the program (which does
> not have to be root) has write access to the root directory of the
> file system. There will certainly be cases where this will not be
> true, however.
xfs_fsr doesn't use these donor files to avoid mtime updates - it
uses invisible IO (i.e. O_NOATIME|O_NOCMTIME) to do that.
Also xfs_fsr needs root permissions because it uses the XFS
open-by-handle interfaces. Indeed, it doesn't always use tmp donor
dirs in the root directory - it only ever does that when doing an
entire fs re-organisation. If you are just defragging a single file,
it creates the tmp file in the same directory as the file being
defragged...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2012-01-04 4:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-01 20:12 e4defrag modifies folder's mtime Thomas Lindroth
2012-01-03 20:34 ` Ted Ts'o
2012-01-04 4:53 ` Dave Chinner [this message]
2012-01-04 5:27 ` Ted Ts'o
2012-01-04 7:43 ` Dave Chinner
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