Fix extending non LUKSv1 encrypted volumes

Patch fixing bug #1861071 resolved the issue of extending LUKS v1
volumes when nova connects them via libvirt instead of through os-brick,
but nova side still fails to extend in-use volumes when they don't go
through libvirt (i.e., LUKS v2).

The logs will show a very similar error, but the user won't know that
this has happened and Cinder will show the new size:

 libvirt.libvirtError: internal error: unable to execute QEMU command
 'block_resize': Cannot grow device files

There are 2 parts to this problem:

- The device mapper device is not automatically extended.
- Nova tries to use the encrypted block device size as the size of the
  decrypted device.

This patch leverages the "extend_volume" method in os-brick connectors
to extend the device mapper device, after the encrypted device has been
extended, and use the size of the decrypted volume for the block_resize
operation.

Related change: I351f1a7769c9f915e4cd280f05a8b8b87f40df84
Closes-Bug: #1967157
Change-Id: Ia1411f11ec4bf44af6a42d5f96c8a0903846ed66

1 files changed, 9 insertions, 0 deletions

diff --git a/releasenotes/notes/bug-1967157-extend-encrypted.yaml b/releasenotes/notes/bug-1967157-extend-encrypted.yaml
new file mode 100644
index 0000000000..8ff5f6a2f9
--- /dev/null
+++ b/releasenotes/notes/bug-1967157-extend-encrypted.yaml
@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    Extending attached encrypted volumes that failed before because they were
+    not being decrypted using libvirt (any other than LUKS) now work as
+    expected and the new size will be visible within the instance. See
+    `Bug 1967157`_ for more details.
+
+    .. _Bug 1967157: https://bugs.launchpad.net/nova/+bug/1967157