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Date: Sun, 05 Feb 2012 10:36:39 -0600 From: Eric Sandeen <sandeen@...hat.com> To: Ron Yorston <rmy@...ress.co.uk> CC: xfs@....sgi.com, linux-ext4@...r.kernel.org Subject: Re: sparsify - utility to punch out blocks of 0s in a file On 2/5/12 3:33 AM, Ron Yorston wrote: > Eric Sandeen wrote: > >> Now that ext4, xfs, & ocfs2 can support punch hole, a tool to >> "re-sparsify" a file by punching out ranges of 0s might be in order. >> >> I'll see if util-linux wants it after it gets beat into shape. >> (or did a tool like this already exist and I missed it?) > > Way ahead of you. I wrote my sparsify utility for ext2 in 2004: > > http://intgat.tigress.co.uk/rmy/uml/sparsify.html Cool, I had not known about that one. But that one is a bit less generic - ext2-specific and requiring an unmounted fs, right? > It's mostly of historical interest now, I suppose. The sparsify utility > doesn't work on ext4 and I long since gave up maintaining the kernel > patch. I still use the zerofree utility, though. > > It would be nice to have a modern version of sparsify. I'll try it out. Thanks! Matthias' suggestion of adding SEEK_HOLE/SEEK_DATA makes very good sense too. I should also untie the read/zero buffer size from the minimum hole size, we should do optimal IO sizes regardless of the minimum hole size desired... -Eric > Ron -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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