svn commit: r259765 - in head/sys: fs/nfsserver nfs nfsserver

[Alexander Motin]

On 23.12.2013 13:50, Konstantin Belousov wrote:
> On Mon, Dec 23, 2013 at 01:35:51PM +0200, Alexander Motin wrote:
>> On 23.12.2013 13:14, Konstantin Belousov wrote:
>>> On Mon, Dec 23, 2013 at 08:43:17AM +0000, Alexander Motin wrote:
>>>> Author: mav
>>>> Date: Mon Dec 23 08:43:16 2013
>>>> New Revision: 259765
>>>> URL: http://svnweb.freebsd.org/changeset/base/259765
>>>>
>>>> Log:
>>>>     Fix RPC server threads file handle affinity to work better with ZFS.
>>>>
>>>>       Instead of taking 8 specific bytes of file handle to identify file during
>>>>     RPC thread affitinity handling, use trivial hash of the full file handle.
>>>>     ZFS's struct zfid_short does not have padding field after the length field,
>>>>     as result, originally picked 8 bytes are loosing lower 16 bits of object ID,
>>>>     causing many false matches and unneeded requests affinity to same thread.
>>>>       This fix substantially improves NFS server latency and scalability in SPEC
>>>>     NFS benchmark by more flexible use of multiple NFS threads.
>>>>
>>>>     Sponsored by:	iXsystems, Inc.
>>>
>>> Did you audited all other filesystems to ensure that struct fid.
>>> fid_data0 is filled (zeroed) consistently ?
>>
>> Yes, I did a tree search and in all found cases the structure was
>> pre-erased.
> I.e. you checked all in-tree VOP_VPTOFH implementations, right ?

I checked all call places of VOP_VPTOFH and VOP_FID in a tree. As I can 
see these structures are normally pre-erased by callers.

>>> Also, this constitues subtle VFS KBI change.
>>
>> In what way it touched VFS KBI? I indeed modified RPC FHA KPI to make it
>> more safe, but I don't see how it may touch anything else then two of
>> our NFS servers.
>
> See above, it is now required to ensure that fid_data0 is zeroed, for
> filesystems which only fill fid_data.

I believe the only that really important is that NFS itself erases the 
structure before calling these VFS methods. But I'll recheck NFS code 
once more just to be sure.

-- 
Alexander Motin