Re: [PATCH] fix posix lock on NFS

[Peter Staubach <staubach@redhat.com>]

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