From: Nikos Skalkotos <skalkoto@grnet.gr>
Date: Fri, 24 Aug 2012 09:48:18 +0000 (+0300)
Subject: Make the cow file size equal to the original media
X-Git-Tag: v0.1~29
X-Git-Url: https://code.grnet.gr/git/snf-image-creator/commitdiff_plain/8fed77f7fce8dd2d4793e9300b8aee904b00bdc3

Make the cow file size equal to the original media

The size of the cow file was hardcoded to 1G. This was buggy, because
for a big image, the resize operation could fill up the cow file and
fail.
---

diff --git a/image_creator/disk.py b/image_creator/disk.py
index 7e3b166..c367efd 100644
--- a/image_creator/disk.py
+++ b/image_creator/disk.py
@@ -114,12 +114,12 @@ class Disk(object):
 
         # Take a snapshot and return it to the user
         self.out.output("Snapshotting media source...", False)
-        size = blockdev('--getsize', sourcedev)
+        size = blockdev('--getsz', sourcedev)
         cowfd, cow = tempfile.mkstemp()
         os.close(cowfd)
         self._add_cleanup(os.unlink, cow)
-        # Create 1G cow sparse file
-        dd('if=/dev/null', 'of=%s' % cow, 'bs=1k', 'seek=%d' % (1024 * 1024))
+        # Create cow sparse file
+        dd('if=/dev/null', 'of=%s' % cow, 'bs=512', 'seek=%d' % int(size))
         cowdev = self._losetup(cow)
 
         snapshot = uuid.uuid4().hex