Saving compressed qcow2 file at template saving

TODO: UI for choosing compreesed / uncompressed file format at template save

disk.py

@@ -294,9 +294,10 @@ class Disk(object):
             if 'qcow' in ftype.lower():
                 move(downloaded_file, self.get_path())
             else:
-                cmdline = ['qemu-img',
+	        cmdline = ['ionice', '-c', 'idle',
+			   'qemu-img',
                            'convert',
-                           '-O', 'qcow2',
+                           '-m', '4', '-O', 'qcow2',
                            downloaded_file,
                            self.get_path()]
                 subprocess.check_output(cmdline)
@@ -324,9 +325,12 @@ class Disk(object):
 
     def export(self, task, disk_format, exported_name, upload_link, parent_id):
         exported_path = self.get_path() + '.' + disk_format
-        cmdline = ['qemu-img',
-                   'convert',
-                   '-O', disk_format,
+        cmdline = ['ionice', '-c', 'idle',
+                   'qemu-img',
+                   'convert']
+	if disk_format == 'qcow2':
+	    cmdline += ['-c']
+	cmdline += ['-m', '4', '-O', disk_format,
                    self.get_path(),
                    exported_path]
 
@@ -409,7 +413,8 @@ class Disk(object):
         elif self.format == 'raw':
             raise NotImplemented()
         else:
-            cmdline = ['qemu-img',
+            cmdline = ['ionice', '-c', 'idle',
+                       'qemu-img',
                        'create',
                        '-b', self.get_base(),
                        '-f', self.format,
@@ -420,13 +425,14 @@ class Disk(object):
     def merge_disk_with_base(self, task, new_disk, parent_id=None):
         proc = None
         try:
-            cmdline = [
-                'qemu-img', 'convert', self.get_path(),
-                '-O', new_disk.format, new_disk.get_path()]
+            cmdline = ['ionice', '-c', 'idle', 'qemu-img', 'convert', '-m', '4']
+	    if new_disk.format == 'qcow2':
+		cmdline += ['-c']
+            cmdline += ['-O', new_disk.format, self.get_path(), new_disk.get_path()]
             # Call subprocess
             logger.debug(
-                "Merging %s into %s.", self.get_path(),
-                new_disk.get_path())
+                "Merging %s into %s. %s", self.get_path(),
+                new_disk.get_path(), cmdline)
             percent = 0
             diff_disk = Disk.get(self.dir, self.name)
             base_disk = Disk.get(self.dir, self.base_name)