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From: Peter Staubach <staubach@redhat.com>
To: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Matthew Wilcox <matthew@wil.cx>,
	ASANO Masahiro <masano@tnes.nec.co.jp>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] fix posix lock on NFS
Date: Wed, 04 Jan 2006 09:16:10 -0500	[thread overview]
Message-ID: <43BBD8AA.2010906@redhat.com> (raw)
In-Reply-To: <1136337847.7846.50.camel@lade.trondhjem.org>

Trond Myklebust wrote:

>On Tue, 2006-01-03 at 15:09 -0500, Peter Staubach wrote:
>  
>
>>Matthew Wilcox wrote:
>>    
>>
>>>Mandatory locks aren't mandatory for other clients.
>>> 
>>>
>>>      
>>>
>>So?
>>
>>I guess that I don't understand this response.
>>
>>The server is responsible for keeping itself from attempting to access
>>a mandatory lock file.  The client is not responsible for doing so and
>>trying to help the server is kind of a waste of time, mostly.
>>
>>The mandatory lock mode bits really only come into play when attempting
>>to read or write the file.  In this case, the system will automatically
>>try to take a lock for the process, if that process does not already
>>have a lock.  The server should prevent itself from trying to access
>>files like this in order to avoid DoS attacks.
>>
>>The NFS client does not support mandatory locking, mostly due to the
>>possibility of DoS attacks and also due to the locking and NFS protocols
>>not being sufficiently aware of each other.  NFSv4 can be used to address
>>this latter problem, but probably not the former.
>>
>>So, why deny lock requests for such files?  Especially on the client?
>>    
>>
>
>I agree, however that would have been a change in behaviour that would
>have been hard to find time to test properly in an -rc6(?) release, so
>we went for the quick and dirty fix.
>

Okay.

Are we going to be able to fix this properly once things open up a bit then?

    Thanx...

       ps

      reply	other threads:[~2006-01-04 14:16 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-12-22  4:24 [PATCH] fix posix lock on NFS ASANO Masahiro
2006-01-03 19:39 ` Peter Staubach
2006-01-03 19:46   ` Matthew Wilcox
2006-01-03 20:09     ` Peter Staubach
2006-01-04  1:24       ` Trond Myklebust
2006-01-04 14:16         ` Peter Staubach [this message]

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