Pass access rules to driver on snapshot revert

In order to revert to a snapshot in the LVM driver (and
very likely other drivers) the list of access rules is
needed, so this change modifies the driver interface to
provide this extra information.

This change requires preventing a revert to snapshot
operation while access rules on the affected share are
out of sync.

Closes bug: 1658133

Change-Id: Ia6678bb0e484f9c8f8b05d90e514801ae9baa94b

manila/share/drivers/lvm.py

@@ -362,7 +362,13 @@ class LVMShareDriver(LVMMixin, driver.ShareDriver):
         self._extend_container(share, device_name, new_size)
         self._execute('resize2fs', device_name, run_as_root=True)
 
-    def revert_to_snapshot(self, context, snapshot, share_server=None):
+    def revert_to_snapshot(self, context, snapshot, access_rules,
+                           share_server=None):
+        share = snapshot['share']
+        # Temporarily remove all access rules
+        self._get_helper(share).update_access(self.share_server,
+                                              share['name'], [], [], [])
+        # Unmount the filesystem
         self._remove_export(context, snapshot)
         # First we merge the snapshot LV and the share LV
         # This won't actually do anything until the LV is reactivated
@@ -370,7 +376,6 @@ class LVMShareDriver(LVMMixin, driver.ShareDriver):
                                   snapshot['name'])
         self._execute('lvconvert', '--merge', snap_lv_name, run_as_root=True)
         # Unmount the share so we can deactivate it
-        share = snapshot['share']
         self._unmount_device(share)
         # Deactivate the share LV
         share_lv_name = "%s/%s" % (self.configuration.lvm_share_volume_group,
@@ -381,11 +386,15 @@ class LVMShareDriver(LVMMixin, driver.ShareDriver):
         self._execute('lvchange', '-ay', share_lv_name, run_as_root=True)
         # Now recreate the snapshot that was destroyed by the merge
         self._create_snapshot(context, snapshot)
-        # Finally we can mount the share again
+        # At this point we can mount the share again
         device_name = self._get_local_path(share)
         self._mount_device(share, device_name)
         device_name = self._get_local_path(snapshot)
         self._mount_device(snapshot, device_name)
+        # Lastly we add all the access rules back
+        self._get_helper(share).update_access(self.share_server,
+                                              share['name'], access_rules,
+                                              [], [])
 
     def create_snapshot(self, context, snapshot, share_server=None):
         self._create_snapshot(context, snapshot)