NFSv4: nfs4_locku_done must release the sequence id

commit 2b1bc308 upstream.

If the state recovery machinery is triggered by the call to
nfs4_async_handle_error() then we can deadlock.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

fs/nfs/nfs4proc.c

@@ -4150,6 +4150,7 @@ static void nfs4_locku_done(struct rpc_task *task, void *data)
 			if (nfs4_async_handle_error(task, calldata->server, NULL) == -EAGAIN)
 				rpc_restart_call_prepare(task);
 	}
+	nfs_release_seqid(calldata->arg.seqid);
 }
 
 static void nfs4_locku_prepare(struct rpc_task *task, void *data)