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Date: Fri, 24 Feb 2017 18:06:06 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Hans Liljestrand <ishkamiel@gmail.com>,
        Al Viro <viro@zeniv.linux.org.uk>, linux-kernel@vger.kernel.org,
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        linux-fsdevel@vger.kernel.org, Chris Mason <clm@fb.com>,
        gregkh@linuxfoundation.org, elena.reshetova@intel.com
Subject: Re: [RFC][PATCH 02/10] fs: Avoid looking at i_count without i_lock
 held
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On Fri, Feb 24, 2017 at 08:56:06AM -0800, Linus Torvalds wrote:
> This one looks very questionable.
> 
> Taking the lock for every single inode, even when we can tell that it's
> pointless, is horrid.
> 
> Even if you really think you found a race, i think it would be better to
> leave the unlocked read around as an optimistic check, and then do a safe
> double check read inside the lock (together with the i_state checks)
> 
> Hmm?

Yeah, pretty dumb that.