Merge b8fdbf8 into c1de61a

drivers/blktap2.py

@@ -977,8 +977,29 @@ def __init__(self, uuid, target, driver_info):
         self._vdi_uuid   = uuid
         self._session    = target.session
         self.xenstore_data = scsiutil.update_XS_SCSIdata(uuid,scsiutil.gen_synthetic_page_data(uuid))
+        self.__o_direct  = None
         self.lock        = Lock("vdi", uuid)
 
+    def get_o_direct_capability(self, options = {}):
+        """Returns True/False based on licensing and caching_params"""
+        if self.__o_direct is not None:
+            return self.__o_direct
+
+        if not util.read_caching_is_restricted(self._session):
+            self.__o_direct = options.get(self.CONF_KEY_O_DIRECT)
+            if self.__o_direct is not None:
+                return self.__o_direct
+            if (self.target.vdi.sr.handles("nfs") or
+                self.target.vdi.sr.handles("ext")):
+                from FileSR import FileVDI
+                if vhdutil.getParent(self.target.vdi.path, FileVDI.extractUuid):
+                    self.__o_direct = False
+
+        if self.__o_direct is None:
+            self.__o_direct = True
+
+        return self.__o_direct
+
     @classmethod
     def from_cli(cls, uuid):
         import VDI as sm
@@ -1469,6 +1490,7 @@ def attach(self, sr_uuid, vdi_uuid, writable, activate = False):
         # Return backend/ link
         back_path = self.BackendLink.from_uuid(sr_uuid, vdi_uuid).path()
         struct = { 'params': back_path,
+                   'o_direct': self.get_o_direct_capability(),
                    'xenstore_data': self.xenstore_data}
         util.SMlog('result: %s' % struct)
 
@@ -1562,12 +1584,7 @@ def _activate(self, sr_uuid, vdi_uuid, options):
             # Maybe launch a tapdisk on the physical link
             if self.tap_wanted():
                 vdi_type = self.target.get_vdi_type()
-                if util.read_caching_is_restricted(self._session):
-                    options["o_direct"] = True
-                else:
-                    options["o_direct"] = options.get(self.CONF_KEY_O_DIRECT)
-                    if options["o_direct"] is None:
-                        options["o_direct"] = True
+                options["o_direct"] = self.get_o_direct_capability(options)
                 dev_path = self._tap_activate(phy_path, vdi_type, sr_uuid,
                         options,
                         self._get_pool_config(sr_uuid).get("mem-pool-size"))