[master 15/19] Factor out aligning of size to resize unit into a separate method.

[dashea]

From: mulhern

Related: #56

Use it where appropriate.

Signed-off-by: mulhern 
---
 blivet/formats/__init__.py | 23 ++++++++++++++++++++---
 blivet/formats/fs.py       |  2 +-
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/blivet/formats/__init__.py b/blivet/formats/__init__.py
index 7fa25cb..0a69ef8 100644
--- a/blivet/formats/__init__.py
+++ b/blivet/formats/__init__.py
@@ -359,6 +359,24 @@ def updateSizeInfo(self):
         """
         pass

+    def _alignToResizeUnit(self, newsize, direction=ROUND_DOWN):
+        """ Returns a new size aligned to the units of the resize tool.
+
+           :param :class:`~.Size` newsize: the proposed new size
+           :returns: newsize modified to yield an aligned size
+           :param direction: one of (decimal.ROUND_UP, decimal.ROUND_DOWN)
+           :rtype: :class:`~.Size`
+
+           The default is to round down.
+
+           If no resize unit available, returns newsize.
+        """
+        try:
+            return newsize.roundToNearest(self._resizeTask.unit, rounding=direction)
+        except NotImplementedError:
+            log.warning("Trying to align size to resize unit, but no resize unit available.")
+            return newsize
+
     def _deviceCheck(self, devspec):
         """ Verifies that device spec has a proper format.

@@ -600,12 +618,11 @@ def resize(self, **kwargs):

def _resize(self, **kwargs):
         """ Do generic resizing actions. """
-        # Bump target size to nearest whole number of the resize tool's units.
+
         # We always round down because the fs has to fit on whatever device
         # contains it. To round up would risk quietly setting a target size too
         # large for the device to hold.
-        rounded = self.targetSize.roundToNearest(self._resizeTask.unit,
-                                                 rounding=ROUND_DOWN)
+        rounded = self._alignToResizeUnit(self.targetSize)

# 1. target size was between the min size and max size values prior to
         #    rounding (see _setTargetSize)
diff --git a/blivet/formats/fs.py b/blivet/formats/fs.py
index f4547ca..bf23ba9 100644
--- a/blivet/formats/fs.py
+++ b/blivet/formats/fs.py
@@ -281,7 +281,7 @@ def _padSize(self, size):

# make sure the padded and rounded min size is not larger than
         # the current size
-        padded = min(padded.roundToNearest(self._resizeTask.unit, rounding=ROUND_UP), self.currentSize)
+        padded = min(self._alignToResizeUnit(padded, ROUND_UP), self.currentSize)

return padded