NFSv4: Add a mapping for NFS4ERR_FILE_OPEN in nfs4_map_errors

With unlink is an asynchronous operation in the sillyrename case, it
expects nfs4_async_handle_error() to map the error correctly.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -107,6 +107,8 @@ static int nfs4_map_errors(int err)
 		return -EPROTONOSUPPORT;
 	case -NFS4ERR_ACCESS:
 		return -EACCES;
+	case -NFS4ERR_FILE_OPEN:
+		return -EBUSY;
 	default:
 		dprintk("%s could not handle NFSv4 error %d\n",
 				__func__, -err);