On Thu, 2010-04-01 at 08:46 -0400, Jeff Layton wrote: > I'm working on an issue in an older kernel where we see occasional > panics when trying to refresh credentials. Here's the bug in case > anyone is interested: > > https://bugzilla.redhat.com/show_bug.cgi?id=572870 > > ...I think I understand the problem well enough now. The problem is > pretty complex, but the issue is that some operations are done using > credentials from a stateowner associated with a nfs_client, but using > the rpc_clnt in nfs_server->client. The two can have different > authtypes if there are a mix of mounts with different authtypes to the > same server. This problem seems to have been fixed in mainline with the > introduction of the auth_generic code. > > It leaves me wondering though...what exactly is the reason for having > two rpc_clients per NFS mount? To clarify, I'm talking about these two, > which seem to be somewhat redundant: > > nfs_server->client > nfs_server->nfs_client->cl_rpcclient > > On mount, the nfs4_set_client calls nfs_get_client to search the list > of nfs_client structs until it finds one that matches the address, port, > etc of the NFS server. If one isn't found, the kernel creates one using > whatever authtype was requested for the mount. > > Later, nfs_init_server_rpcclient looks at the rpc_clnt in the > nfs_client and copies it. If the auth pseudoflavor doesn't match > however, it creates a new rpc_auth for it. > > What exactly is the point of having two rpc_clnt's? Why not just get > always use nfs_client->cl_rpcclient instead of nfs_server->client and > simply have nfs_get_client filter by authtype? > Look again at nfs_init_server_rpcclient(). The pseudoflavour is not the only thing that is changed. We also change the soft flag and the timeout properties of the server->client. The point is that users sometimes want to specify per-mountpoint transport properties, and so we try to give them that possibility, while at the same time sharing sockets/rdma connections. Cheers Trond -- 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
