linux-kernel - Re: [PATCH RFC v3] vfs: make fstatat retry once on ESTALE errors from getattr call

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Date:	Fri, 20 Apr 2012 16:18:37 -0400
From:	Steve Dickson <SteveD@...hat.com>
To:	Jeff Layton <jlayton@...hat.com>
CC:	linux-fsdevel@...r.kernel.org, linux-nfs@...r.kernel.org,
	linux-kernel@...r.kernel.org, miklos@...redi.hu,
	viro@...IV.linux.org.uk, hch@...radead.org,
	michael.brantley@...haw.com, sven.breuner@...m.fraunhofer.de,
	chuck.lever@...cle.com, pstaubach@...grid.com, malahal@...ibm.com,
	bfields@...ldses.org, trond.myklebust@....uio.no, rees@...ch.edu
Subject: Re: [PATCH RFC v3] vfs: make fstatat retry once on ESTALE errors
 from getattr call

On 04/20/2012 10:40 AM, Jeff Layton wrote:
> I guess the questions at this point is:
> 
> 1) How representative is Peter's mkdir_test() of a real-world workload?
Reading your email I had to wonder the same thing... What application 
removes hierarchy of directories in a loop from two different clients?
I would suspect not many, if any... esp over NFS... 
 
> 
> 2) if we assume that it is fairly representative of one, how can we
> achieve retrying indefinitely with NFS, or at least some large finite
> amount?
The amount of looping would be peer speculation. If the problem can
not be handled by one simple retry I would say we simply pass the
error up to the app... Its an application issue... 
 
> 
> I have my doubts as to whether it would really be as big a problem for
> other filesystems as Miklos and others have asserted, but I'll take
> their word for it at the moment. What's the best way to contain this
> behavior to just those filesystems that want to retry indefinitely when
> they get an ESTALE? Would we need to go with an entirely new
> ESTALERETRY after all?
> 
Introducing a new errno to handle this problem would be overkill IMHO...

If we have to go to the looping approach, I would strong suggest we
make the file systems register for this type of behavior...

steved. 
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