NFS/SUNRPC: don't lookup machine credential until rpcauth_bindcred().

When NFS creates a machine credential, it is a "generic" credential,
not tied to any auth protocol, and is really just a container for
the princpal name.
This doesn't get linked to a genuine credential until rpcauth_bindcred()
is called.
The lookup always succeeds, so various places that test if the machine
credential is NULL, are pointless.

As a step towards getting rid of generic credentials, this patch gets
rid of generic machine credentials.  The nfs_client and rpc_client
just hold a pointer to a constant principal name.
When a machine credential is wanted, a special static 'struct rpc_cred'
pointer is used. rpcauth_bindcred() recognizes this, finds the
principal from the client, and binds the correct credential.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

1 files changed, 4 insertions, 17 deletions

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index f142fca6995b..6304c79dbcd1 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -166,28 +166,15 @@ out:
 
 struct rpc_cred *nfs4_get_machine_cred(struct nfs_client *clp)
 {
-	struct rpc_cred *cred = clp->cl_root_cred;
-
-	if (!cred)
-		cred = clp->cl_machine_cred;
-	if (cred)
-		return get_rpccred(cred);
-	return cred;
+	return get_rpccred(rpc_machine_cred());
 }
 
 static void nfs4_root_machine_cred(struct nfs_client *clp)
 {
-	struct rpc_cred *new;
 
-	new = rpc_lookup_machine_cred(NULL);
-	spin_lock(&clp->cl_lock);
-	if (clp->cl_root_cred == NULL) {
-		clp->cl_root_cred = new;
-		new = NULL;
-	}
-	spin_unlock(&clp->cl_lock);
-	if (new != NULL)
-		put_rpccred(new);
+	/* Force root creds instead of machine */
+	clp->cl_principal = NULL;
+	clp->cl_rpcclient->cl_principal = NULL;
 }
 
 static struct rpc_cred *