NFS: move credential expiry tracking out of SUNRPC into NFS.

NFS needs to know when a credential is about to expire so that
it can modify write-back behaviour to finish the write inside the
expiry time.
It currently uses functions in SUNRPC code which make use of a
fairly complex callback scheme and flags in the generic credientials.

As I am working to discard the generic credentials, this has to change.

This patch moves the logic into NFS, in part by finding and caching
the low-level credential in the open_context.  We then make direct
cred-api calls on that.

This makes the code much simpler and removes a dependency on generic
rpc credentials.

Signed-off-by: NeilBrown <[email protected]>
Signed-off-by: Anna Schumaker <[email protected]>
diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index b218e15..03a1cd5 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -1517,23 +1517,10 @@ gss_match(struct auth_cred *acred, struct rpc_cred *rc, int flags)
 		if (gss_cred->gc_principal == NULL)
 			return 0;
 		ret = strcmp(acred->principal, gss_cred->gc_principal) == 0;
-		goto check_expire;
-	}
-	if (gss_cred->gc_principal != NULL)
-		return 0;
-	ret = uid_eq(rc->cr_uid, acred->cred->fsuid);
-
-check_expire:
-	if (ret == 0)
-		return ret;
-
-	/* Notify acred users of GSS context expiration timeout */
-	if (test_bit(RPC_CRED_NOTIFY_TIMEOUT, &acred->ac_flags) &&
-	    (gss_key_timeout(rc) != 0)) {
-		/* test will now be done from generic cred */
-		test_and_clear_bit(RPC_CRED_NOTIFY_TIMEOUT, &acred->ac_flags);
-		/* tell NFS layer that key will expire soon */
-		set_bit(RPC_CRED_KEY_EXPIRE_SOON, &acred->ac_flags);
+	} else {
+		if (gss_cred->gc_principal != NULL)
+			return 0;
+		ret = uid_eq(rc->cr_uid, acred->cred->fsuid);
 	}
 	return ret;
 }