linux-kernel - Re: [PATCH] Add "-e" option to rpc.gssd to allow error on ticket expiry. Try 2 with added man pages.

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Message-ID: <4EC6E047.20800@calvaedi.com>
Date:	Fri, 18 Nov 2011 23:46:31 +0100
From:	John Hughes <john@...vaedi.com>
To:	Trond Myklebust <Trond.Myklebust@...app.com>
CC:	John Hughes <john@...va.com>, Jim Rees <rees@...ch.edu>,
	linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Add "-e" option to rpc.gssd to allow error on ticket
 expiry. Try 2 with added man pages.

On 11/18/2011 11:37 PM, Trond Myklebust wrote:
> On Fri, 2011-11-18 at 23:33 +0100, John Hughes wrote:
>    
>> On 11/18/2011 10:03 PM, Trond Myklebust wrote:
>>      
>>> On Fri, 2011-11-18 at 15:57 -0500, Jim Rees wrote:
>>>
>>>        
>>>> The write() syscall doesn't indicate whether the data is safe or not.  That
>>>> would be the close() syscall.
>>>>
>>>>          
>>> fsync(). Which may succeed if the user renews their ticket first.
>>> However you may still have data loss if dirty data has been lost because
>>> of EKEYEXPIRED returns on the WRITE RPC call...
>>>
>>>        
>> Only if the write(2) returned EKEYEXPIRED, surely,
>>      
> What part of "write is asynchronous" is so hard to understand?
>    

If write succeeds,
and the write rpc fails
and data is lost
and fsync succeeds
then the nfs client is broken.

d'accord?

>    
>> I would want to know if data was lost.
>> Intuition means nothing if I get an error.
>>
>> If it were possible I'd like:
>>
>> 1. write works
>> 1a. WRITE RPC fails, data stays in cache
>> 2. ticket renewed
>> 3. fsync works, data written
>>      
> Which is _exactly_ how it works today, so what is the problem?
>
>    
Well, the hang after step 1a.

If there is to be a hang I'd like it when the fsync is done.

(And no hang if no fsync).


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