From mboxrd@z Thu Jan  1 00:00:00 1970
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From: Andrew Morton <akpm@zip.com.au>
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Subject: Re: [linux-lvm] LVM2 modifies the buffer_head struct?
References: message from Jens Axboe on Wednesday July 3 <15651.54044.557070.109158@notabene.cse.unsw.edu.au>
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Date: Thu Jul  4 00:39:02 2002
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To: Neil Brown <neilb@cse.unsw.edu.au>
Cc: Jens Axboe <axboe@suse.de>, Joe Thornber <joe@fib011235813.fsnet.co.uk>, linux-lvm@sistina.com, linux-kernel@vger.kernel.org

Neil Brown wrote:
> 
> ...
> We just want ext3/jbd to make sure that it only calls bh2jh on
> an unlocked buffer... is that easy?

It's feasible, but a downright pita.

> Ofcourse this ceases to be an issue in 2.5 because the filesys uses
> pages or buffer_heads and the device driver uses bios.

Well, for 2.4 I'd be inclined to just add the extra field to 
struct buffer_head and be done with it.

Current sizeof(buffer_head) is 96 bytes, and making that 100 would
be a nuisance, but its quite easy to shrink the buffer_head a
bit (replace b_inode with BH_inode, say...).

-