linux-ext4 - Re: [BUG] ext2/3/4: dio reads stale data when we do some append dio writes

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Message-ID: <20131119110147.GA3323@infradead.org>
Date:	Tue, 19 Nov 2013 03:01:47 -0800
From:	Christoph Hellwig <hch@...radead.org>
To:	linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [BUG] ext2/3/4: dio reads stale data when we do some append dio
 writes

On Tue, Nov 19, 2013 at 06:45:08PM +0800, Zheng Liu wrote:
> BTW, that would be great if you could give me some comments about this
> problem itself.  Is it a generic problem in vfs?  Or just a feature by
> design?

It seems like a fundamental issue with ext4 (and most older Linux
filesystems) trying to do dio reads without locking out writers.

If you have a shared/exclusive lock to protect dio reads against
buffered or appending writers like XFS does this issue is properly
prevented.
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