NFS: Add migration recovery callouts in nfs4proc.c

When a server returns NFS4ERR_MOVED, trigger the new migration
recovery logic in the state manager.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -384,6 +384,11 @@ static int nfs4_handle_exception(struct nfs_server *server, int errorcode, struc
 		case -NFS4ERR_STALE_CLIENTID:
 			nfs4_schedule_lease_recovery(clp);
 			goto wait_on_recovery;
+		case -NFS4ERR_MOVED:
+			ret = nfs4_schedule_migration_recovery(server);
+			if (ret < 0)
+				break;
+			goto wait_on_recovery;
 #if defined(CONFIG_NFS_V4_1)
 		case -NFS4ERR_BADSESSION:
 		case -NFS4ERR_BADSLOT:
@@ -431,6 +436,8 @@ static int nfs4_handle_exception(struct nfs_server *server, int errorcode, struc
 	return nfs4_map_errors(ret);
 wait_on_recovery:
 	ret = nfs4_wait_clnt_recover(clp);
+	if (test_bit(NFS_MIG_FAILED, &server->mig_status))
+		return -EIO;
 	if (ret == 0)
 		exception->retry = 1;
 	return ret;
@@ -2974,11 +2981,16 @@ static int nfs4_get_referral(struct rpc_clnt *client, struct inode *dir,
 	status = nfs4_proc_fs_locations(client, dir, name, locations, page);
 	if (status != 0)
 		goto out;
-	/* Make sure server returned a different fsid for the referral */
+
+	/*
+	 * If the fsid didn't change, this is a migration event, not a
+	 * referral.  Cause us to drop into the exception handler, which
+	 * will kick off migration recovery.
+	 */
 	if (nfs_fsid_equal(&NFS_SERVER(dir)->fsid, &locations->fattr.fsid)) {
 		dprintk("%s: server did not return a different fsid for"
 			" a referral at %s\n", __func__, name->name);
-		status = -EIO;
+		status = -NFS4ERR_MOVED;
 		goto out;
 	}
 	/* Fixup attributes for the nfs_lookup() call to nfs_fhget() */
@@ -4739,6 +4751,10 @@ nfs4_async_handle_error(struct rpc_task *task, const struct nfs_server *server,
 		case -NFS4ERR_STALE_CLIENTID:
 			nfs4_schedule_lease_recovery(clp);
 			goto wait_on_recovery;
+		case -NFS4ERR_MOVED:
+			if (nfs4_schedule_migration_recovery(server) < 0)
+				goto recovery_failed;
+			goto wait_on_recovery;
 #if defined(CONFIG_NFS_V4_1)
 		case -NFS4ERR_BADSESSION:
 		case -NFS4ERR_BADSLOT:
@@ -4769,6 +4785,8 @@ nfs4_async_handle_error(struct rpc_task *task, const struct nfs_server *server,
 	rpc_sleep_on(&clp->cl_rpcwaitq, task, NULL);
 	if (test_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) == 0)
 		rpc_wake_up_queued_task(&clp->cl_rpcwaitq, task);
+	if (test_bit(NFS_MIG_FAILED, &server->mig_status))
+		goto recovery_failed;
 restart_call:
 	task->tk_status = 0;
 	return -EAGAIN;