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.
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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