New BlockDev methods to get spindles

Two new methods are created to get the number of spindles, one alone, and
one together with size. For devices that don't support spindles, None is
returned.
Signed-off-by: Bernardo Dal Seno <bdalseno@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>

lib/storage/base.py

@@ -330,6 +330,28 @@ class BlockDev(object):
       ThrowError("Failed to parse blockdev output: %s", str(err))
     return sz
 
+  def GetActualSpindles(self):
+    """Return the actual number of spindles used.
+
+    This is not supported by all devices; if not supported, C{None} is returned.
+
+    @note: the device needs to be active when this is called
+
+    """
+    assert self.attached, "BlockDevice not attached in GetActualSpindles()"
+    return None
+
+  def GetActualDimensions(self):
+    """Return the actual disk size and number of spindles used.
+
+    @rtype: tuple
+    @return: (size, spindles); spindles is C{None} when they are not supported
+
+    @note: the device needs to be active when this is called
+
+    """
+    return (self.GetActualSize(), self.GetActualSpindles())
+
   def __repr__(self):
     return ("<%s: unique_id: %s, children: %s, %s:%s, %s>" %
             (self.__class__, self.unique_id, self._children,

lib/storage/bdev.py

@@ -746,6 +746,13 @@ class LogicalVolume(base.BlockDev):
         return
     base.ThrowError("Can't grow LV %s: %s", self.dev_path, result.output)
 
+  def GetActualSpindles(self):
+    """Return the number of spindles used.
+
+    """
+    assert self.attached, "BlockDevice not attached in GetActualSpindles()"
+    return len(self.pv_names)
+
 
 class FileStorage(base.BlockDev):
   """File device.