> On Jan 24, 2017, at 2:53 PM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
>
> On Tue, Jan 24, 2017 at 02:41:40PM -0500, J. Bruce Fields wrote:
>> On Tue, Jan 24, 2017 at 02:31:37PM -0500, Chuck Lever wrote:
>>> Adding a justification is OK with me, and please replace the
>>> list of steps with my updated list above.
>>>
>>> However, your explanation implies that Solaris is the only server
>>> that might need this fix. Actually _any_ server that supports
>>> transparent state migration needs clients to get this fix. Lock
>>> operations on a file that has moved are not able to update the
>>> sequence ID on the destination server.
>>
>> Are you sure? Couldn't an implementation include a server-to-server
>> protocol that allowed the source and destination server to share stateid
>> information?
>>
>> But even if that's possible, it may be unnecessarily complicated, so I
>> agree I shouldn't be claiming it's a Solaris-specific issue (though it
>> may be worth documenting that's who first hit this).
>>
>> --b.
>>
>>> This backwards-compatible change is OK because:
>>>
>>> - No servers in the wild support migration yet, thus
>>> NFS4ERR_MOVED is never returned by existing servers
>
> I think you mean "transparent state migration" there?
Yes, though I'm not aware of any public implementations
that support plain migration either.
NFS4ERR_MOVED can also be returned in cases where servers want
to advertise replicas, but we don't expect that status on
seqid-mutating operations like LOCK.
> A server supporting non-transparent state migration could return
> NFS4ERR_MOVED on a LOCK operation, but the client won't be able to use
> that stateid afterwards in that case anyway.
>
>>> - Clients that do not support migration should never receive
>>> NFS4ERR_MOVED on a state-mutating operation
>
> I didn't think there was a way for clients to advertise non-support for
> migration?
Not in NFSv4.0, but NFSv4.1 has an EXCHANGE_ID flag that signifies
client support for migration.
> But such clients could never recover from MOVED anyway, so we're not
> making things worse for them.
Exactly.
> --b.
>
>>>
>>> In other words, this change is necessary only for clients that
>>> support TSM.
>>>
>>> Salt to taste.
>>>
>>>
>>>> --b.
>>>>
>>>>>
>>>>>
>>>>>> --b.
>>>>>>
>>>>>>>>
>>>>>>>> Reported-by: Xuan Qi <xuan.qi@xxxxxxxxxx>
>>>>>>>> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
>>>>>>>> Cc: stable@xxxxxxxxxxxxxxx # v3.7+
>>>>>>>> ---
>>>>>>>> include/linux/nfs4.h | 3 ++-
>>>>>>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>>>>>>>
>>>>>>>> diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
>>>>>>>> index bca5363..1b1ca04 100644
>>>>>>>> --- a/include/linux/nfs4.h
>>>>>>>> +++ b/include/linux/nfs4.h
>>>>>>>> @@ -282,7 +282,7 @@ enum nfsstat4 {
>>>>>>>>
>>>>>>>> static inline bool seqid_mutating_err(u32 err)
>>>>>>>> {
>>>>>>>> - /* rfc 3530 section 8.1.5: */
>>>>>>>> + /* See RFC 7530, section 9.1.7 */
>>>>>>>> switch (err) {
>>>>>>>> case NFS4ERR_STALE_CLIENTID:
>>>>>>>> case NFS4ERR_STALE_STATEID:
>>>>>>>> @@ -291,6 +291,7 @@ static inline bool seqid_mutating_err(u32 err)
>>>>>>>> case NFS4ERR_BADXDR:
>>>>>>>> case NFS4ERR_RESOURCE:
>>>>>>>> case NFS4ERR_NOFILEHANDLE:
>>>>>>>> + case NFS4ERR_MOVED:
>>>>>>>> return false;
>>>>>>>> };
>>>>>>>> return true;
>>>>>>>>
>>>>>>>> --
>>>>>>>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
>>>>>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>>>>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>>>>>>
>>>>>>> --
>>>>>>> Chuck Lever
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
>>>>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>>>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>>>>> --
>>>>>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
>>>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>>>>
>>>>> --
>>>>> Chuck Lever
>>>>>
>>>>>
>>>> --
>>>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>>
>>> --
>>> Chuck Lever
>>>
>>>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Chuck Lever
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
