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From: Andreas Dilger <adilger@sun.com>
To: Francis Moreau <francis.moro@gmail.com>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: PG_updatodate vs BH_updatodate
Date: Sat, 22 Nov 2008 22:19:38 -0600	[thread overview]
Message-ID: <20081123041938.GW3186@webber.adilger.int> (raw)
In-Reply-To: <m2prko3ff4.fsf@gmail.com>

On Nov 21, 2008  23:03 +0100, Francis Moreau wrote:
> I'm wondering if there's any difference between these 2 flags except
> that one is a page flag and the other one is a buffer head flag.
> 
> But in my understanding these 2 flags means that the page contains
> uptodate data. So the buffer head flag seems useless since it could be
> calculated from bh->b_page->flags.

There may be multiple buffers on a single page, and in some cases one
buffer on a page can be uptodate while another buffer on the same page
is not.  This can be confusing at times, but I don't know if there is
any easy way to avoid it.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.


  reply	other threads:[~2008-11-23  4:19 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-11-21 22:03 PG_updatodate vs BH_updatodate Francis Moreau
2008-11-23  4:19 ` Andreas Dilger [this message]
2008-11-23 12:14   ` Francis Moreau
2008-11-23 12:21     ` Matthew Wilcox
2008-11-23 20:14       ` Francis Moreau
2008-11-24 15:56         ` Jörn Engel
2008-11-24 16:42           ` Francis Moreau

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