> On Jan 24, 2017, at 2:15 PM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
>
> On Tue, Jan 24, 2017 at 02:06:16PM -0500, Chuck Lever wrote:
>>
>>> On Jan 23, 2017, at 11:49 AM, bfields@xxxxxxxxxxxx wrote:
>>>
>>> On Mon, Jan 23, 2017 at 10:01:27AM -0500, Chuck Lever wrote:
>>>>
>>>>> On Jan 22, 2017, at 2:04 PM, Chuck Lever <chuck.lever@xxxxxxxxxx> wrote:
>>>>>
>>>>> Xuan Qi reports that the Linux NFSv4 client failed to lock a file
>>>>> that was migrated. The steps he observed on the wire:
>>>>>
>>>>> 1. The client sent a LOCK request
>>>>> 2. The server replied NFS4ERR_MOVED
>>>>> 3. The client switched to the destination server
>>>>> 4. The client sent the LOCK request again with a bumped
>>>>> lock sequence ID
>>>>> 5. The server rejected the LOCK request with NFS4ERR_BAD_SEQID
>>>>
>>>> The list of steps could be more clear:
>>>>
>>>> 1. The client sent a LOCK request to the source server
>>>> 2. The source server replied NFS4ERR_MOVED
>>>> 3. The client switched to the destination server
>>>> 4. The client sent the same LOCK request to the destination
>>>> server with a bumped lock sequence ID
>>>> 5. The destination server rejected the LOCK request with
>>>> NFS4ERR_BAD_SEQID
>>>>
>>>>
>>>>> RFC 3530 section 8.1.5 provides a list of NFS errors which do not
>>>>> bump a lock sequence ID.
>>>>>
>>>>> However, RFC 3530 is now obsoleted by RFC 7530. In RFC 7530 section
>>>>> 9.1.7, this list has been updated by the addition of NFS4ERR_MOVED.
>>>
>>> I guess we figured the backwards-incompatible change was OK since
>>> essentially the Solaris server is the first we know of to be making real
>>> use of NFS4ERR_MOVED?
>>>
>>> And probably it's required for the their implementation because the old
>>> server no longer has the ability to update the state once it's reached
>>> the point of returning ERR_MOVED.
>>>
>>> OK, makes sense to me, I think.
>>
>> Hi Bruce-
>>
>> Does this mean you will take this patch, or should
>> I just add your Reviewed-by: ?
>
> I can take it if nobody objects. Mind if I append the above to the
> changelog? (Just want to document why we think the apparently
> backwards-incompatible change is OK.)
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.
This backwards-compatible change is OK because:
- No servers in the wild support migration yet, thus
NFS4ERR_MOVED is never returned by existing servers
- Clients that do not support migration should never receive
NFS4ERR_MOVED on a state-mutating operation
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;
>>>>>
>>>>> --
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>>>>
>>>> --
>>>> Chuck Lever
>>>>
>>>>
>>>>
>>>> --
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>>> --
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>>
>> --
>> Chuck Lever
>>
>>
> --
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--
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