linux-ext4 - Re: Question on huge

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Message-ID: <4A5760A7.60607@redhat.com>
Date:	Fri, 10 Jul 2009 10:39:19 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	Curt Wohlgemuth <curtw@...gle.com>
CC:	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: Question on huge_file

Curt Wohlgemuth wrote:
> I apologize if this is a dumb question, but I'm having trouble
> understanding the huge_file superblock flag.
> 
> I see how, if this flag is set, that the inode can have a size > 2**32
> bytes, using the i_size_lo/i_size_high fields.
> 
> But since an ext4_extent only uses 32-bits for for its ee_block field
> to represent the logical block, how can an extent describe any block
> range of a file past the 4GiB boundary?
> 
> Am I missing something?

i_size_lo/hi is in bytes, ee_block is in .... blocks.

so 2^32 blocks is a lot more than 2^32 bytes, and i_size_hi/lo are
needed to contain it.  I think.  :)

-Eric
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