remoteloop: drop O_DIRECT

Appart from giving us a hard time on s390x, this feature did not seem
to have a measurable effect. Moreover, O_DIRECT is not supported by
tmpfs so without this patch we could not use tmpfs as backing store,
which does speed up image generation considerably.

Drop the flag and and rather put the store on tmpfs in order to speed
things up.

osbuild/remoteloop.py

@@ -4,7 +4,6 @@ import contextlib
 import errno
 import json
 import os
-import platform
 import socket
 import threading
 from . import loop
@@ -133,13 +132,8 @@ class LoopClient:
     def device(self, filename, offset=None, sizelimit=None):
         req = {}
         fds = array.array("i")
-        oflags = os.O_RDWR
 
-        if platform.machine() != "s390x":
-            # O_DIRECT will break s390x currently
-            oflags |= os.O_DIRECT
-
-        fd = os.open(filename, oflags)
+        fd = os.open(filename, os.O_RDWR)
         dir_fd = os.open("/dev", os.O_DIRECTORY)
 
         fds.append(fd)