On Apr 26, 2012, at 3:14 PM, Myklebust, Trond wrote: > On Thu, 2012-04-26 at 15:04 -0400, Chuck Lever wrote: >> On Apr 26, 2012, at 2:53 PM, Myklebust, Trond wrote: >> >>> On Thu, 2012-04-26 at 14:43 -0400, Chuck Lever wrote: >>>> On Apr 26, 2012, at 12:55 PM, Myklebust, Trond wrote: >>>> >>>>> On Thu, 2012-04-26 at 12:24 -0400, Chuck Lever wrote: >>>>>> On Apr 23, 2012, at 4:55 PM, Chuck Lever wrote: >>>>> Then lets move the flavour out of the clientid string, >>>> >>>> Removing the flavor from the nfs_client_id4 string makes sense. >>>> >>>>> and just settle >>>>> for handling CLID_INUSE by changing the flavour on the SETCLIENTID call. >>>> >>>> This is where I get hazy. >>>> >>>> If I simply change the authentication flavor on the existing clp->cl_rpcclient, will this affect ongoing RENEW operations that also use this transport? Do we want subsequent RENEW operations to use the new flavor? >>>> >>>> Thinking hypothetically, it seems to me that CLID_INUSE is really an indication of a permanent configuration error, or a software bug, and we should not bother to recover. But maybe that's my limited imagination. Under what use cases do you think CLID_INUSE might occur and it might be useful to attempt recovery? >>>> >>> >>> The server caches the principal name that was used to call SETCLIENTID >>> when the lease was established. Any attempt to call SETCLIENTID with a >>> different principal will result in CLID_INUSE unless the lease has >>> expired. >>> >>> So what I was proposing wasn't that you try to change the authentication >>> flavour on an existing nfs_client. It was that when you are probing, you >>> can use the CLID_INUSE reply from SETCLIENTID as a direct indication >>> that the server is indeed trunked, and that you already hold a lease on >>> that server, but that the authentication flavour that you are trying to >>> use is wrong. >> >> The use case would be that my client has mounted a server via address X using authentication flavor 1, and then tries to mount the same server via address Y using authentication flavor 2. > > ...for which the result should be that all setclientid/confirm and renew > requests will use flavour 1. Agreed. >> Do we even need to retry the SETCLIENTID and to perform a SETCLIENTID_CONFIRM in that case? > > Yes. Otherwise we end up with 2 leases on the same server. I don't see how... If the second SETCLIENTID fails with CLID_INUSE then the server still has the first lease that's using flavor 1. "Boom, done." >> Now, what about nfs4_reclaim_lease() ? If the client sees CLID_INUSE during a lease reclaim, no trunking discovery is involved. > > That would mean that the lease was expired, and that someone sent a > SETCLIENTID call to the server using our clientid string, but using the > wrong principal. There are 2 cases: > > 1) Someone is spoofing our client. I've no idea how to recover from > this, short of changing the clientid string. Maybe we should keep cl_uniquifier for case 1...? Since nfs4_reclaim_lease() is called in the state manager, it has to do something to recover or make the waiting process error out. > 2) The server is trunked, the lease expired, and we happened to call > 'mount' while it was expired, and inadvertently sent a SETCLIENTID > +SETCLIENTID_CONFIRM call to the server using a different IP address, > and using the wrong principal. The clid_init_mutex should exclude this case...? -- Chuck Lever chuck[dot]lever[at]oracle[dot]com -- 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
