launchpad-reviewers team mailing list archive

[Michael Hudson-Doyle <mwhudsonlp@xxxxxxxxxxx>]

Michael Hudson-Doyle has proposed merging lp:~mwhudson/launchpad-buildd/lp-1852518-again into lp:launchpad-buildd.

Commit message:
Do not make assumptions about what device major number the device mapper is using. (LP: #1852518)

Requested reviews:
  Launchpad code reviewers (launchpad-reviewers)
Related bugs:
  Bug #1852518 in launchpad-buildd: "livecd-rootfs focal hangs during kpartx (ubuntu-cpc project)"
  https://bugs.launchpad.net/launchpad-buildd/+bug/1852518

For more details, see:
https://code.launchpad.net/~mwhudson/launchpad-buildd/lp-1852518-again/+merge/375987
-- 
Your team Launchpad code reviewers is requested to review the proposed merge of lp:~mwhudson/launchpad-buildd/lp-1852518-again into lp:launchpad-buildd.

=== modified file 'debian/changelog'
--- debian/changelog	2019-11-22 11:15:29 +0000
+++ debian/changelog	2019-11-26 00:10:48 +0000
@@ -1,3 +1,10 @@
+launchpad-buildd (182) UNRELEASED; urgency=medium
+
+  * Do not make assumptions about what device major number the device mapper
+    is using. (LP: #1852518) 
+
+ -- Michael Hudson-Doyle <michael.hudson@xxxxxxxxxx>  Tue, 26 Nov 2019 13:07:24 +1300
+
 launchpad-buildd (181) xenial; urgency=medium
 
   [ Robert C Jennings ]

=== modified file 'debian/control'
--- debian/control	2019-01-28 15:12:54 +0000
+++ debian/control	2019-11-26 00:10:48 +0000
@@ -38,6 +38,7 @@
          bzip2,
          debootstrap,
          dpkg-dev,
+         dmsetup,
          file,
          lsb-release,
          lsof,

=== modified file 'lpbuildd/target/lxd.py'
--- lpbuildd/target/lxd.py	2019-11-21 18:26:06 +0000
+++ lpbuildd/target/lxd.py	2019-11-26 00:10:48 +0000
@@ -35,6 +35,23 @@
 LXD_RUNNING = 103
 
 
+def get_device_mapper_major():
+    """Return the major device number used by the devicemapper on this system.
+
+    This is not consistent across kernel versions, sadly.
+    """
+    created = False
+    if not os.path.exists("/dev/dm-0"):
+        created = True
+        subprocess.check_call(
+            ["dmsetup", "create", "tmpdevice", "--notable"])
+    major = os.major(os.stat("/dev/dm-0").st_rdev)
+    if created:
+        subprocess.check_call(
+            ["dmsetup", "remove", "tmpdevice"])
+    return major
+
+
 fallback_hosts = dedent("""\
     127.0.0.1\tlocalhost
     ::1\tlocalhost ip6-localhost ip6-loopback
@@ -448,10 +465,11 @@
 
         # Create dm-# devices.  On focal kpartx looks for dm devices and hangs
         # in their absence.
+        major = get_device_mapper_major()
         for minor in range(8):
             self.run(
                 ["mknod", "-m", "0660", "/dev/dm-%d" % minor,
-                 "b", "251", str(minor)])
+                 "b", str(major), 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