GlusterFS: Copy snap from correct source file

The GlusterFS driver's copy_volume_from_snapshot was previously
not parsing the snapshot information to determine which backing
file to copy from, instead copying from the active file at all
times.  This would result in the wrong data being supplied when
a volume is cloned from a snapshot.

Add a test for the copy_volume_from_snapshot method.

Closes-Bug: #1222907
Change-Id: Ib829ca1a6812b61845f3b2eb9c5507779fa6ec15

diff --git a/cinder/tests/test_glusterfs.py b/cinder/tests/test_glusterfs.py
index 4f6c7aec6069eb2da0182058ee4f66ac6cd84631..ef34fd4634460175c43ee9fe5ea1f6e7feaa07b5 100644 (file)
--- a/cinder/tests/test_glusterfs.py
+++ b/cinder/tests/test_glusterfs.py
@@ -1435,6 +1435,57 @@ class GlusterFsDriverTestCase(test.TestCase):
         self.assertEqual(len(chain), 1)
         self.assertEqual(chain[0]['filename'], vol_filename)
 
+    def test_copy_volume_from_snapshot(self):
+        (mox, drv) = self._mox, self._driver
+
+        mox.StubOutWithMock(image_utils, 'convert_image')
+        mox.StubOutWithMock(drv, '_read_info_file')
+        mox.StubOutWithMock(image_utils, 'qemu_img_info')
+
+        dest_volume = self._simple_volume(
+            'c1073000-0000-0000-0000-0000000c1073')
+        src_volume = self._simple_volume()
+
+        vol_dir = os.path.join(self.TEST_MNT_POINT_BASE,
+                               drv._get_hash_str(self.TEST_EXPORT1))
+        src_vol_path = os.path.join(vol_dir, src_volume['name'])
+        dest_vol_path = os.path.join(vol_dir, dest_volume['name'])
+        info_path = os.path.join(vol_dir, src_volume['name']) + '.info'
+
+        snapshot = {'volume_name': src_volume['name'],
+                    'name': 'clone-snap-%s' % src_volume['id'],
+                    'size': src_volume['size'],
+                    'volume_size': src_volume['size'],
+                    'volume_id': src_volume['id'],
+                    'id': 'tmp-snap-%s' % src_volume['id'],
+                    'volume': src_volume}
+
+        snap_file = dest_volume['name'] + '.' + snapshot['id']
+        snap_path = os.path.join(vol_dir, snap_file)
+
+        size = dest_volume['size']
+
+        drv._read_info_file(info_path).AndReturn(
+            {'active': snap_file,
+             snapshot['id']: snap_file}
+        )
+
+        qemu_img_output = """image: %s
+        file format: raw
+        virtual size: 1.0G (1073741824 bytes)
+        disk size: 173K
+        backing file: %s
+        """ % (snap_file, src_volume['name'])
+        img_info = image_utils.QemuImgInfo(qemu_img_output)
+
+        image_utils.qemu_img_info(snap_path).AndReturn(img_info)
+
+        image_utils.convert_image(src_vol_path, dest_vol_path, 'raw')
+
+        mox.ReplayAll()
+
+        drv._copy_volume_from_snapshot(snapshot, dest_volume, size)
+
     def test_create_volume_from_snapshot(self):
         (mox, drv) = self._mox, self._driver
 

diff --git a/cinder/volume/drivers/glusterfs.py b/cinder/volume/drivers/glusterfs.py
index b16d5384c4912df28b4975b1cb371626feb3a2aa..96f12bf591962c6bb19d8f2472b56fe3ce2d09ed 100644 (file)
--- a/cinder/volume/drivers/glusterfs.py
+++ b/cinder/volume/drivers/glusterfs.py
@@ -233,18 +233,29 @@ class GlusterfsDriver(nfs.RemoteFsDriver):
                      'vol': volume['id'],
                      'size': volume_size})
 
-        path_to_disk = self._local_path_volume(snapshot['volume'])
+        info_path = self._local_path_volume_info(snapshot['volume'])
+        snap_info = self._read_info_file(info_path)
+        vol_path = self._local_volume_dir(snapshot['volume'])
+        forward_file = snap_info[snapshot['id']]
+        forward_path = os.path.join(vol_path, forward_file)
+
+        # Find the file which backs this file, which represents the point
+        # when this snapshot was created.
+        img_info = self._qemu_img_info(forward_path)
+        path_to_snap_img = os.path.join(vol_path, img_info.backing_file)
 
         path_to_new_vol = self._local_path_volume(volume)
 
-        LOG.debug(_("will copy from snapshot at %s") % path_to_disk)
+        LOG.debug(_("will copy from snapshot at %s") % path_to_snap_img)
 
         if self.configuration.glusterfs_qcow2_volumes:
             out_format = 'qcow2'
         else:
             out_format = 'raw'
 
-        image_utils.convert_image(path_to_disk, path_to_new_vol, out_format)
+        image_utils.convert_image(path_to_snap_img,
+                                  path_to_new_vol,
+                                  out_format)
 
     def delete_volume(self, volume):
         """Deletes a logical volume."""
@@ -287,6 +298,10 @@ class GlusterfsDriver(nfs.RemoteFsDriver):
             If the volume is attached, the VM will switch to this file as
             part of the snapshot process.
 
+            Note that volume-1234.aaaa represents changes after snapshot
+            'aaaa' was created.  So the data for snapshot 'aaaa' is actually
+            in the backing file(s) of volume-1234.aaaa.
+
             This file has a qcow2 header recording the fact that volume-1234 is
             its backing file.  Delta changes since the snapshot was created are
             stored in this file, and the backing file (volume-1234) does not