On 7/16/2015 11:36, Kinglong Mee wrote:
> On 7/16/2015 04:49, J. Bruce Fields wrote:
>> On Wed, Jul 15, 2015 at 04:47:48PM -0400, J. Bruce Fields wrote:
>>> On Mon, Jul 13, 2015 at 05:29:41PM +0800, Kinglong Mee wrote:
>>>> Commit 294ac32e99 "nfsd: protect clid and verifier generation with client_lock"
>>>> have moved gen_confirm() to gen_clid().
>>>
>>> This means the statement in that earlier commit is wrong:
>>>
>>>
>>> With this, there's no need to keep two counters as they'd always
>>> be in sync anyway, so just use the clientid_counter for both.
>>>
>>> Looks to me like this may need a separate counter to eliminate the
>>> possibibility of returning the same confirm twice for a one clientid?
>
> Yes, nfsd will generate same confirm for one clientid in one second.
>
> verf[0] = (__force __be32)jiffies;
> verf[1] = (__force __be32)nn->clientid_counter;
>
> for case 1: probable callback update, the new unconf client needs
> a different confirm.
Ignore this patch, and just revert commit 294ac32e99
"nfsd: protect clid and verifier generation with client_lock"
is a better solve.
thanks,
Kinglong Mee
>
> Rereading rfc7530,
> x be the value of the client.id subfield of the SETCLIENTID4args
> structure.
>
> v be the value of the client.verifier subfield of the
> SETCLIENTID4args structure.
>
> c be the value of the client ID field returned in the
> SETCLIENTID4resok structure.
>
> k represent the value combination of the callback and callback_ident
> fields of the SETCLIENTID4args structure.
>
> s be the setclientid_confirm value returned in the SETCLIENTID4resok
> structure.
>
> { v, x, c, k, s } be a quintuple for a client record. A client
> record is confirmed if there has been a SETCLIENTID_CONFIRM
> operation to confirm it. Otherwise, it is unconfirmed. An
> unconfirmed record is established by a SETCLIENTID call.
>
> ... /* case 1: probable callback update */ ...
>
> o The server checks if it has recorded a confirmed record for { v,
> x, c, l, s }, where l may or may not equal k. If so, and since
> the id verifier v of the request matches that which is confirmed
> and recorded, the server treats this as a probable callback
> information update and records an unconfirmed { v, x, c, k, t }
> and leaves the confirmed { v, x, c, l, s } in place, such that
> t != s. It does not matter whether k equals l or not. Any
> pre-existing unconfirmed { v, x, c, *, * } is removed.
>
> The server returns { c, t }. It is indeed returning the old
> clientid4 value c, because the client apparently only wants to
> update callback value k to value l. It's possible this request is
> one from the Byzantine router that has stale callback information,
> but this is not a problem. The callback information update is
> only confirmed if followed up by a SETCLIENTID_CONFIRM { c, t }.
>
> The server awaits confirmation of k via SETCLIENTID_CONFIRM
> { c, t }.
>
> The server does NOT remove client (lock/share/delegation) state
> for x.
>
>>
>> (but frankly I can never completely review changes to the
>> setclientid/setclientid_confirm behavior without rereading RFC 7530
>> 16.33.5 every time, which is a slog. Might help to contrive a pynfs
>> test derived from that text which tests for this particular behavior.)
>>
>
> Make sense.
> I will make it later.
>
> thanks,
> Kinglong Mee
>
>
>>>
>>> --b.
>>>
>>>>
>>>> After it, setclientid will return a bad reply with all zero confirms
>>>> after copy_clid().
>>>>
>>>> Signed-off-by: Kinglong Mee <kinglongmee@xxxxxxxxx>
>>>> ---
>>>> fs/nfsd/nfs4state.c | 5 +++--
>>>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>>>> index e0a4556..b1f84fc 100644
>>>> --- a/fs/nfsd/nfs4state.c
>>>> +++ b/fs/nfsd/nfs4state.c
>>>> @@ -3042,10 +3042,11 @@ nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>>>> unconf = find_unconfirmed_client_by_name(&clname, nn);
>>>> if (unconf)
>>>> unhash_client_locked(unconf);
>>>> - if (conf && same_verf(&conf->cl_verifier, &clverifier))
>>>> + if (conf && same_verf(&conf->cl_verifier, &clverifier)) {
>>>> /* case 1: probable callback update */
>>>> copy_clid(new, conf);
>>>> - else /* case 4 (new client) or cases 2, 3 (client reboot): */
>>>> + gen_confirm(new, nn);
>>>> + } else /* case 4 (new client) or cases 2, 3 (client reboot): */
>>>> gen_clid(new, nn);
>>>> new->cl_minorversion = 0;
>>>> gen_callback(new, setclid, rqstp);
>>>> --
>>>> 2.4.3
>>
>
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