NFSv4: Remove requirement for machine creds for the "renew" operation

 In RFC3530, the RENEW operation is allowed to use either

 the same principal, RPC security flavour and (if RPCSEC_GSS), the same
  mechanism and service that was used for SETCLIENTID_CONFIRM

 OR

 Any principal, RPC security flavour and service combination that
 currently has an OPEN file on the server.

 Choose the latter since that doesn't require us to keep credentials for
 the same principal for the entire duration of the mount.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/nfs4renewd.c b/fs/nfs/nfs4renewd.c
index f62c2f7..5d764d8 100644
--- a/fs/nfs/nfs4renewd.c
+++ b/fs/nfs/nfs4renewd.c
@@ -62,6 +62,7 @@
 nfs4_renew_state(void *data)
 {
 	struct nfs4_client *clp = (struct nfs4_client *)data;
+	struct rpc_cred *cred;
 	long lease, timeout;
 	unsigned long last, now;
 
@@ -77,7 +78,8 @@
 	timeout = (2 * lease) / 3 + (long)last - (long)now;
 	/* Are we close to a lease timeout? */
 	if (time_after(now, last + lease/3)) {
-		if (list_empty(&clp->cl_state_owners)) {
+		cred = nfs4_get_renew_cred(clp);
+		if (cred == NULL) {
 			set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
 			spin_unlock(&clp->cl_lock);
 			nfs_expire_all_delegations(clp);
@@ -85,7 +87,8 @@
 		}
 		spin_unlock(&clp->cl_lock);
 		/* Queue an asynchronous RENEW. */
-		nfs4_proc_async_renew(clp);
+		nfs4_proc_async_renew(clp, cred);
+		put_rpccred(cred);
 		timeout = (2 * lease) / 3;
 		spin_lock(&clp->cl_lock);
 	} else