Re: Write delegation

[Andy Adamson <andros@netapp.com>]

On Aug 4, 2010, at 3:21 PM, Yudong Gao wrote:

> Hi,
> 
> I am not able to find the implementation of directory delegation,
> either. Similarly, the callback functions CB_NOTIFY is not
> implemented, either. I find that in preprocss_nfs41_op() in
> callback_xdr.c, whenever a CB_NOTIFY is encountered, an
> NFS4ERR_NOTSUPP is returned directly.

CB_NOTIFY is not currently supported on the Linux NFS client.

> 
> Am I missing something? Or they are just not supported in the current version?
> 
> Thanks a lot!
> 
> best,
> 
> Yudong
> 
> On Mon, Aug 2, 2010 at 5:17 PM, Yudong Gao <stgyd@umich.edu> wrote:
>> Hi,
>> 
>> I am looking at the delegation implementation in the source code of
>> NFS 4.1 in kernel 2.6.32.15. I can find the code for read delegation,
>> which is working and can serve the read requests locally. But I can
>> never find the code about write delegation, which is supposed to cache
>> the write update locally. I try to look at the functions including
>> nfs_writepage(s), nfs_file_flush() but none of them checks or uses the
>> write delegation.
>> 
>> Is write delegation currently implemented in NFS 4.1?

Write delegation is supported but I don't think write behavior changes - writes are still cached and flushed as without a write delegation. The write delegation does prevent open/close and lock/locku from being put on the wire.

-->Andy

>> 
>> Thanks!
>> 
>> best,
>> 
>> Yudong
>> 
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