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Date: Fri, 15 Nov 2013 06:29:23 -0800
From: Christoph Hellwig <hch@infradead.org>
To: Chuck Lever <chuck.lever@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>, Trond.Myklebust@netapp.com,
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Subject: Re: [PATCH 6/7] nfs: take i_mutex during direct I/O reads
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On Thu, Nov 14, 2013 at 12:00:06PM -0500, Chuck Lever wrote:
> > We'll need the i_mutex to prevent i_dio_count from incrementing while
> > truncate is waiting for it to reach zero, and protects against having
> > the pagecache repopulated after we flushed it.
> 
> How was the performance impact of this change measured?

I've only done correctness tests.