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Date: Fri, 9 Jun 2006 18:04:41 -0400
From: Theodore Tso <tytso@mit.edu>
To: Jeff Garzik <jeff@garzik.org>
Cc: Michael Poole <mdpoole@troilus.org>, Gerrit Huizenga <gh@us.ibm.com>,
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       linux-kernel@vger.kernel.org, Christoph Hellwig <hch@infradead.org>,
       cmm@us.ibm.com, linux-fsdevel@vger.kernel.org
Subject: Re: [Ext2-devel] [RFC 0/13] extents and 48bit ext3
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On Fri, Jun 09, 2006 at 05:53:14PM -0400, Jeff Garzik wrote:
> Yes, it's not a small change to the on-disk format.
> 
> If you write tools that read an ext3 filesystem, you won't be able to 
> read file data at all, without updating your code.

Most tools that read an ext2/3 filesystem directly use the libext2fs
library, and it will definitely be the case that for files smaller
than 4TB, even on a filesystem with extents enabled, as long as you
are using a version of libext2fs which is extents-aware, it will work
without any changes.

For files larger than 4TB, we will need some kind of LFS-like
interface change (i.e., ext2fs_file_llseek64 vs. ext2fs_file_llseek),
but that should be the only change needed by the tool.

					- Ted