Merge lp:~rcj/launchpad-buildd/lp1852518 into lp:launchpad-buildd

[Robert C Jennings]

LXD: Create dm-X devices to address kpartx hangs (LP: #1852518)

On focal kpartx looks for dm devices and hangs in their absense.

[Robert C Jennings (rcj)]

WIP to pursue a fix in the distro rather than add a work-around

[Robert C Jennings (rcj)]

With the rejection of an upstream bug https://github.com/systemd/systemd/issues/14033 could you reconsider this MP?

The presence of the device nodes is a sufficient workaround and the alternative workaround in the binary hooks, like https://code.launchpad.net/~mwhudson/livecd-rootfs/+git/livecd-rootfs/+merge/375588, is less pleasant (plus it has to be fixed in a number of places). Thank you.

[Colin Watson (cjwatson)]

I'm OK with this in principle, but this change breaks the test suite. Could you fix that, please? (Use "make check" in a xenial container with launchpad-buildd's build-deps installed.)

======================================================================
FAIL: lpbuildd.target.tests.test_lxd.TestLXD.test_start
----------------------------------------------------------------------
Traceback (most recent call last):
  File "lpbuildd/target/tests/test_lxd.py", line 376, in test_start
    MatchesListwise(expected_args))
  File "/usr/lib/python2.7/dist-packages/testtools/testcase.py", line 435, in assertThat
    raise mismatch_error
testtools.matchers._impl.MismatchError: Differences: [
20 != 28: Length mismatch
!=:
reference = ['lxc',
 'exec',
 'lp-xenial-amd64',
 '--',
 'linux64',
 'mkdir',
 '-p',
 '/etc/systemd/system/snapd.service.d']
actual = ['lxc',
 'exec',
 'lp-xenial-amd64',
 '--',
 'linux64',
 'mknod',
 '-m',
 '0660',
 '/dev/dm-0',
 'b',
 '251',
 '0']

!=:
reference = ['lxc',
 'exec',
 'lp-xenial-amd64',
 '--',
 'linux64',
 'ln',
 '-s',
 '/dev/null',
 '/etc/systemd/system/snapd.refresh.timer']
actual = ['lxc',
 'exec',
 'lp-xenial-amd64',
 '--',
 'linux64',
 'mknod',
 '-m',
 '0660',
 '/dev/dm-1',
 'b',
 '251',
 '1']

]

review: Needs Fixing

[Robert C Jennings (rcj)]

Sorry cjwatson, will fix and mark ready for review again

[Robert C Jennings (rcj)]

Tests updated and now passing, ready for review again.

[Colin Watson (cjwatson)]

review: Approve

[Robert C Jennings (rcj)]

Shoot, sorry on the typo

=== modified file 'debian/changelog'
--- debian/changelog	2019-11-06 11:12:41 +0000
+++ debian/changelog	2019-11-21 17:03:19 +0000
@@ -1,3 +1,9 @@
+launchpad-buildd (181) UNRELEASED; urgency=medium
+
+  * LXD: Create dm-X devices to address kpartx hangs (LP: #1852518)
+
+ -- Robert C Jennings <[e-mail]>  Wed, 13 Nov 2019 18:07:32 -0800
+
 launchpad-buildd (180) xenial; urgency=medium
 
   * No-change release to work around production upgrade problem.

=== modified file 'lpbuildd/target/lxd.py'
--- lpbuildd/target/lxd.py	2019-06-09 07:49:21 +0000
+++ lpbuildd/target/lxd.py	2019-11-21 17:03:19 +0000
@@ -446,6 +446,13 @@
                 ["mknod", "-m", "0660", "/dev/loop%d" % minor,
                  "b", "7", str(minor)])
 
+        # Create dm-# devices.  On focal kpartx looks for dm devices and hangs
+        # in their absense.
+        for minor in range(8):
+            self.run(
+                ["mknod", "-m", "0660", "/dev/dm-%d" % minor,
+                 "b", "251", str(minor)])
+
         # XXX cjwatson 2017-09-07: With LXD < 2.2 we can't create the
         # directory until the container has started.  We can get away with
         # this for the time being because snapd isn't in the buildd chroots.

=== modified file 'lpbuildd/target/tests/test_lxd.py'
--- lpbuildd/target/tests/test_lxd.py	2019-06-09 07:49:21 +0000
+++ lpbuildd/target/tests/test_lxd.py	2019-11-21 17:03:19 +0000
@@ -363,6 +363,12 @@
                     lxc +
                     ["mknod", "-m", "0660", "/dev/loop%d" % minor,
                      "b", "7", str(minor)]))
+        for minor in range(8):
+            expected_args.append(
+                Equals(
+                    lxc +
+                    ["mknod", "-m", "0660", "/dev/dm-%d" % minor,
+                     "b", "251", str(minor)]))
         expected_args.extend([
             Equals(
                 lxc + ["mkdir", "-p", "/etc/systemd/system/snapd.service.d"]),