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From: Ted Ts'o <tytso@mit.edu>
To: Andreas Dilger <adilger@dilger.ca>
Cc: Kazuya Mio <k-mio@sx.jp.nec.com>, ext4 <linux-ext4@vger.kernel.org>
Subject: Re: ext4: Fix 32bit overflow in ext4_ext_find_goal()
Date: Sun, 2 Jan 2011 23:11:57 -0500	[thread overview]
Message-ID: <20110103041157.GE11955@thunk.org> (raw)
In-Reply-To: <F02D88CD-7463-4E10-A012-D2CE362D1E88@dilger.ca>

On Sun, Jan 02, 2011 at 08:35:39PM -0700, Andreas Dilger wrote:
> It was written that way because HPC applications writing to a shared
> file normally write to an offset of task_num * task_data_size so
> they do not overlap, and end up with a dense file. Similarly,
> bittorrent and parallel FTP clients will write dense files after
> seeking randomly around the file, and database files often end up
> dense as well.
> 
> I'd rather fix the relatively few applications that expect
> permanently sparse files to use fadvise() to notify the kernel of
> this.

Agreed, and I'm not sure there are enough applications that expect
permanently sparse files that's worth adding a new fadvise().  But if
we do add a new fadvise(), the default should clearly be the current
behavior.

If someone knows of use cases where permanently sparse files are
common, please let us know!

						- Ted

  reply	other threads:[~2011-01-03  4:12 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-13  5:37 [PATCH] ext4: Fix 32bit overflow in ext4_ext_find_goal() Kazuya Mio
2011-01-02 21:40 ` Ted Ts'o
2011-01-03  3:35   ` Andreas Dilger
2011-01-03  4:11     ` Ted Ts'o [this message]
2011-01-03  7:02       ` Amir Goldstein
2011-01-03 17:25       ` Eric Sandeen
2011-01-03 15:36   ` Rogier Wolff

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