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From: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 10/11] hfsplus: optimize fsync
Date: Thu, 18 Nov 2010 15:16:57 +0100
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Cc: Christoph Hellwig <hch@lst.de>, linux-fsdevel@vger.kernel.org
To: Nick Piggin <npiggin@gmail.com>
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On Fri, Nov 19, 2010 at 01:13:55AM +1100, Nick Piggin wrote:
> >> Anyway, what if writeback noticed pagecache was cleaned at this point, and then
> >> clears I_DIRTY bits from inode before you test it above? Won't that leave your
> >> metadata not on disk?
> 
> I'm not sure if you answered this, though. Can't background writeout go through
> and clear the I_DIRTY_* bits on your inode, so that a subsequent fsync will skip
> required writeout because i_state is clean, but your private dirty
> bits are still set?
> 
> That was my (poorly worded) concern.

Good point - we should just skip the sync_inode_metadata for that case.
Which already is a no-op if no dirty bits are set, so just removing the
I_DIRTY check probably is the best thing we can do here.