linux-ext4 - Re: Question on huge

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Date:	Fri, 10 Jul 2009 09:31:20 -0700
From:	Curt Wohlgemuth <curtw@...gle.com>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: Question on huge_file

Hi Eric:

On Fri, Jul 10, 2009 at 8:39 AM, Eric Sandeen<sandeen@...hat.com> wrote:
> 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.  :)

Oops.  Of course.  I knew it had to be something simple.

Thanks,
Curt
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