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: >> >>> For NFSv4 minor version 0, currently the cl_id_uniquifier allows the >>> Linux client to generate a unique nfs_client_id4 string whenever a >>> server replies with NFS4ERR_CLID_INUSE. >>> >>> NFS4ERR_CLID_INUSE actually means that the client has presented this >>> nfs_client_id4 string with a different authentication flavor in the >>> past. Retrying with a different nfs_client_id4 string means the >>> client orphans NFSv4 state on the server. This state will take at >>> least a whole lease period to be purged. >>> >>> Change recovery to try the identification operation again with a >>> different auth flavor until it works. The retry loop is factored >>> out of nfs4_proc_setclientid() and into the state manager, so that >>> both mv0 and mv1 client ID establishment is covered by the same >>> CLID_INUSE recovery logic. >>> >>> XXX: On further review, I'm not sure how it would be possible to >>> send an nfs_client_id4 with the wrong authentication flavor, since >>> the au_name is part of the string itself... >> >> I'm having other doubts about this whole approach. >> >> In the loop in nfs4_reclaim_lease(), the client will need to replace the RPC transport for each retried flavor, and then continue using the transport that worked. New mounts clone their transport from the nfs_client, even if its authentication flavor does not match what might have been specified on the mount. (I haven't checked this, is it true?) It looks like nfs_init_server_rpcclient() changes the flavor of the RPC transport that was cloned from cl_rpcclient, so that shouldn't be a problem. >> What's more, there's no way a server can identify a re-used nfs_client_id4, since we currently plant the authentication flavor in the nfs_client_id4 string… >> >> In fact, because we generate nfs_client_id4 strings with the flavor built in, won't each flavor used on a mount generate a separate lease on the server? > > 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? -- 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
