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Re: sparsify - utility to punch out blocks of 0s in a file

To: Andreas Dilger <adilger@xxxxxxxxx>
Subject: Re: sparsify - utility to punch out blocks of 0s in a file
From: Matthias Schniedermeyer <ms@xxxxxxx>
Date: Sun, 5 Feb 2012 18:23:02 +0100
Cc: Eric Sandeen <sandeen@xxxxxxxxxx>, "linux-ext4@xxxxxxxxxxxxxxx" <linux-ext4@xxxxxxxxxxxxxxx>, Ron Yorston <rmy@xxxxxxxxxxxxx>, "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>
In-reply-to: <9C5B5C07-B0E4-4D13-BCFE-7F35162DF5E8@xxxxxxxxx>
References: <4F2D8F30.3090802@xxxxxxxxxx> <201202050933.q159XQpB026380@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx> <4F2EB017.5090006@xxxxxxxxxx> <9C5B5C07-B0E4-4D13-BCFE-7F35162DF5E8@xxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On 05.02.2012 09:55, Andreas Dilger wrote:

> > Matthias' suggestion of adding SEEK_HOLE/SEEK_DATA makes very good sense 
> > too.
> 
> I thought about this, but if SEEK_HOLE/SEEK_DATA (or FIEMAP) worked, then the 
> file would already be sparse, so I don't think that will help in this case...

With that argumentation you wouldn't need the tool in the first place.

"How can a bunch of zeros be in a file in the first place?"
"Can only be because of the deficiency of another program."

And who is to say that you wouldn't want to repeat such a thing from 
time to time, without SEEK_HOLE/SEEK_DATE you MAY crunch through big 
regions of zeros for no gain at all.



Bis denn

-- 
Real Programmers consider "what you see is what you get" to be just as 
bad a concept in Text Editors as it is in women. No, the Real Programmer
wants a "you asked for it, you got it" text editor -- complicated, 
cryptic, powerful, unforgiving, dangerous.

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