Fstab cleanup fix

Formats with multiple layers (e.g. LUKS) were not handled properly in
fstab. This resulted in fstab entries not being properly cleaned from
fstab when destroy actions were executed. This fixes the issue by using
different variables with correct values based on action type.

blivet/actionlist.py

@@ -292,7 +292,7 @@ def process(self, callbacks=None, devices=None, fstab=None, dry_run=None):
             # (device may not exist afterwards)
             if not skip_fstab:
                 try:
-                    entry = fstab.entry_from_device(action.device)
+                    entry = fstab.entry_from_action(action)
                 except ValueError:
                     # this device should not be in fstab
                     bae_entry = None

blivet/fstab.py

@@ -391,11 +391,48 @@ def entry_from_device(self, device):
         entry.spec = self._get_spec(device)
         if entry.spec is None:
             entry.spec = getattr(device, "fstab_spec", None)
-
         entry.vfstype = device.format.type
 
         return entry
 
+    def entry_from_action(self, action):
+        """ Generate FSTabEntry object based on given blivet Action
+
+            :keyword action: action to process
+            :type action: :class: `blivet.deviceaction.DeviceAction`
+            :returns: fstab entry object based on device processed by action
+            :rtype: :class: `FSTabEntry`
+        """
+
+        if not action.is_format:
+            raise ValueError("""cannot generate fstab entry from action '%s' because
+                                its type is not 'format'""" % action)
+
+        fmt = action.format
+        if action.is_destroy:
+            fmt = action.orig_format
+        if action.is_create:
+            fmt = action.device.format
+
+        entry = FSTabEntry()
+
+        entry.file = None
+        if fmt.mountable:
+            entry.file = fmt.mountpoint
+        elif fmt.type == "swap":
+            entry.file = "swap"
+        else:
+            raise ValueError("""cannot generate fstab entry from action '%s' because
+                                it is neither mountable nor swap type""" % action)
+
+        entry.spec = self._get_spec(action.device)
+        if entry.spec is None:
+            entry.spec = getattr(action.device, "fstab_spec", None)
+
+        entry.vfstype = action.device.format.type
+
+        return entry
+
     def read(self):
         """ Read the fstab file from path stored in self.src_file. Resets currently loaded table contents.
         """
@@ -696,7 +733,11 @@ def _get_spec(self, device):
         # Use "globally" set (on FSTabManager level) spec type otherwise
 
         spec = None
-        spec_type = device.format.fstab.spec_type or self.spec_type
+
+        if hasattr(device.format, 'fstab') and device.format.fstab.spec_type:
+            spec_type = device.format.fstab.spec_type
+        else:
+            spec_type = self.spec_type
 
         if spec_type == "LABEL" and device.format.label:
             spec = "LABEL=%s" % device.format.label
@@ -737,7 +778,7 @@ def update(self, action, bae_entry):
             # does not have UUID assigned yet, so we skip that one
             return
 
-        if action.is_create and action.device.format.mountable:
+        if action.is_create and action.is_format and action.device.format.mountable:
             # add the device to the fstab
             # make sure it is not already present there
             try: