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Date: Wed, 14 Nov 2001 22:55:24 -0700
From: Andreas Dilger <adilger@turbolabs.com>
To: "Peter T. Breuer" <ptb@it.uc3m.es>,
        linux kernel <linux-kernel@vger.kernel.org>
Subject: Re: blocks or KB? (was: .. current meaning of blk_size array)
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On Nov 15, 2001  00:34 -0500, William Park wrote:
> Judging by 'driver/block/nbd.c', it counts by BLOCK_SIZE=1204
> (BLOCK_SIZE_BITS=10), even though you can set the block size to
> [512,1024,...,PAGE_SIZE=4096].  Since NBD counts this 1KB block using
> 'u64' integer, the ultimate size of filesystem is determined by the
> kernel block device support.
> 
> Looking at 'fs/block_dev.c', you can set the block size to
> [512,1024,...,PAGE_SIZE=4096] also.  But, 'max_block()' returns block
> count in whatever block size of the device, not in BLOCK_SIZE:

Sadly, while you _might_ be able to change the BLOCK_SIZE to be something
other than 1kB, there are probably so many places that assume a 1kB size
that you will need a lot of fixing.  I'm not saying that fixing these
things is bad (it would actually be good for many reasons), but just a
heads-up that changing the BLOCK_SIZE define _probably_ won't get you 8TB
devices (maybe a broken system, or corrupt fs instead).  Use caution.

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/

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