[OpenAFS-devel] Re: some requests

[Derrick J Brashear]

On Mon, 21 Feb 2005, Jeffrey Hutzelman wrote:

>> # 04:
>> "why is afs not updating ctime, mtime and atime in the filesystem and
>> what needs to be done , to update this fields ..."
>> 
>> What I've found:
>> - there are 2 dates stored for a vnode:
>>         - "ClientModTime" - modification time measured at the client side
>>         - "ServerModTime" - modification time measured at the server side
>>         ServerModTime is used only for partial dumps/releases.
>>         ClientModTime is transmitted for all 3 types of times: ctime,
>> mtime, atime         (it means you always get only the mtime)
>> - possibilities:
>> 	- updating "atime" is ambiguous/meaningless (multiple clients with
>> cache, additional network load) 	- only ctime support could be 
>> implemented
>> 		- I'm not sure, but maybe volume format change is needed, too 
>> (I'm
>> still examining src/vol) 		- fileserver interface must be 
>> extended
>
>
> In practice, the _real_ difference between ctime and mtime is that users are 
> allowed to change the mtime of files they own (both in and out of AFS), and 
> they are not allowed to change the ctime.  Would having the cache manager 
> report the ServerModTime as the ctime meet your needs?  This could be done 
> fairly trivially as a runtime configuration option in the client, without 
> requiring any changes to the protocol or server.

Also, iirc Athena has patches already to implement it; While it's simple 
to implement their patches are well-tested.