NFSv4: renewd needs to be able to handle the NFS4ERR_CB_PATH_DOWN error

The NFSv4 spec does not specify that the server must repeat that error,
so in order to avoid having the delegations revoked, we should handle
it immediately.

Also note that NFS4ERR_CB_PATH_DOWN does in fact renew the lease...
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4_fs.h

@@ -350,6 +350,7 @@ extern void nfs4_close_sync(struct nfs4_state *, fmode_t);
 extern void nfs4_state_set_mode_locked(struct nfs4_state *, fmode_t);
 extern void nfs4_schedule_lease_recovery(struct nfs_client *);
 extern void nfs4_schedule_state_manager(struct nfs_client *);
+extern void nfs4_schedule_path_down_recovery(struct nfs_client *clp);
 extern void nfs4_schedule_stateid_recovery(const struct nfs_server *, struct nfs4_state *);
 extern void nfs41_handle_sequence_flag_errors(struct nfs_client *clp, u32 flags);
 extern void nfs41_handle_recall_slot(struct nfs_client *clp);

fs/nfs/nfs4proc.c

@@ -3374,9 +3374,13 @@ static void nfs4_renew_done(struct rpc_task *task, void *calldata)
 
 	if (task->tk_status < 0) {
 		/* Unless we're shutting down, schedule state recovery! */
-		if (test_bit(NFS_CS_RENEWD, &clp->cl_res_state) != 0)
+		if (test_bit(NFS_CS_RENEWD, &clp->cl_res_state) == 0)
+			return;
+		if (task->tk_status != NFS4ERR_CB_PATH_DOWN) {
 			nfs4_schedule_lease_recovery(clp);
-		return;
+			return;
+		}
+		nfs4_schedule_path_down_recovery(clp);
 	}
 	do_renew_lease(clp, timestamp);
 }

fs/nfs/nfs4state.c

@@ -1038,6 +1038,12 @@ void nfs4_schedule_lease_recovery(struct nfs_client *clp)
 	nfs4_schedule_state_manager(clp);
 }
 
+void nfs4_schedule_path_down_recovery(struct nfs_client *clp)
+{
+	nfs_handle_cb_pathdown(clp);
+	nfs4_schedule_state_manager(clp);
+}
+
 static int nfs4_state_mark_reclaim_reboot(struct nfs_client *clp, struct nfs4_state *state)
 {