[Bug 1861941] Re: bcache by-uuid links disappear after mounting bcache0
Brian Murray
1861941 at bugs.launchpad.net
Tue Oct 27 17:16:22 UTC 2020
Hello Ryan, or anyone else affected,
Accepted systemd into focal-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/systemd/245.4-4ubuntu3.3 in a few
hours, and then in the -proposed repository.
Please help us by testing this new package. See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed. Your feedback will aid us getting this
update out to other Ubuntu users.
If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, what testing has been
performed on the package and change the tag from verification-needed-
focal to verification-done-focal. If it does not fix the bug for you,
please add a comment stating that, and change the tag to verification-
failed-focal. In either case, without details of your testing we will
not be able to proceed.
Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in
advance for helping!
N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.
** Changed in: systemd (Ubuntu Focal)
Status: In Progress => Fix Committed
** Tags removed: verification-done verification-done-focal
** Tags added: verification-needed verification-needed-focal
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https://bugs.launchpad.net/bugs/1861941
Title:
bcache by-uuid links disappear after mounting bcache0
Status in bcache-tools package in Ubuntu:
Fix Released
Status in linux package in Ubuntu:
Fix Released
Status in systemd package in Ubuntu:
Fix Released
Status in bcache-tools source package in Bionic:
Fix Released
Status in systemd source package in Bionic:
Won't Fix
Status in bcache-tools source package in Focal:
Fix Released
Status in systemd source package in Focal:
Fix Committed
Bug description:
SRU TEAM: The last 2 commits show a summary for the merges/changes
I added some specific (to Bionic) notes in the template.
Thanks!
[Impact]
* bcache-tools udev created symlinks might disappear when other udev
events are processed for the same devices.
* after mkfs.XXX in /dev/bcacheY you might face a condition where
/dev/bcache/by-{uuid,label}/zzz symlinks are gone.
* /dev/bcache/by-{uuid,label}/ symlinks are important so bcache
devices can be addressed by their UUIDs and not the ordering they were
assembled (MAAS depends on this feature, for example).
* it was also discussed in this bug that systemd-udev should *not*
populate /dev/disk/by-uuid/ with symlinks of disks that were bcache
backing devices. this was turned into a discussion whether blkid
should report those or not, and this discussion "died" after sometime.
This last item is what the systemd update is all about: to disallow
/dev/disk/by-XXX/yyyy creation for bcache backing devices (a simple
change that will reduce end users confusion).
[Test Case]
* The reproducer script is here:
https://paste.ubuntu.com/p/37KGy2Smnp/
* Bionic can't reproduce the issue with the 18.04 kernel, nor with
the HWE kernel. Nevertheless, it is preferable that Bionic also do the
same thing: to read bcache superblock and feed environment for
/dev/bcache/by-{uuid,label} symlinks creation.
[Regression Potential]
* We are not depending on bcache device udev events any more when
creating the /dev/bcache/by-{uuid,label}/ symlinks. Instead, we are
depending on a wrapper script that heads bcache device superblock. If
there is a bug in this wrapper the symlinks wouldn't work.
* Previously we were thinking in asking the kernel team to remove the
bcache udev event delta script they've done for previous case (LP:
#1729145). It creates the udev events that were being read and filling
the symlinks. We decided not to remove those (just from Groovy and on)
so we don't need to worry on Breaks/Conflicts in between the kernel
package and bcache-tools (and udev)).
* Long story short: kernel will continue to emit bcache udev events
as it did previously but now those events won't be used by anything -
after installing this SRU - because udev wrapper script is doing this
job (and doing it properly)
[Other Info]
- Original Description:
1.
root at ubuntu:~# lsb_release -rd
Description: Ubuntu Focal Fossa (development branch)
Release: 20.04
2.
root at ubuntu:~# lsb_release -rd
Description: Ubuntu Focal Fossa (development branch)
Release: 20.04
root at ubuntu:~# apt-cache policy linux-image-virtual
linux-image-virtual:
Installed: 5.4.0.12.15
Candidate: 5.4.0.12.15
Version table:
*** 5.4.0.12.15 500
500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
100 /var/lib/dpkg/status
root at ubuntu:~# apt-cache policy linux-image-5.4.0-12-generic
linux-image-5.4.0-12-generic:
Installed: 5.4.0-12.15
Candidate: 5.4.0-12.15
Version table:
*** 5.4.0-12.15 500
500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
100 /var/lib/dpkg/status
3. mount /dev/bcache0 && ls -al /dev/bcache/by-uuid/
+ ls -al /dev/bcache/by-uuid/
total 0
drwxr-xr-x 2 root root 60 Feb 4 23:31 .
drwxr-xr-x 3 root root 60 Feb 4 23:31 ..
lrwxrwxrwx 1 root root 13 Feb 4 23:31 abdfd1f6-44ce-4266-91db-24667b9ae51a -> ../../bcache0
4.
root at ubuntu:~# ls -al /dev/bcache/by-uuid
ls: cannot access '/dev/bcache/by-uuid': No such file or directory
ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-image-5.4.0-12-generic 5.4.0-12.15
ProcVersionSignature: Ubuntu 5.4.0-12.15-generic 5.4.8
Uname: Linux 5.4.0-12-generic x86_64
ApportVersion: 2.20.11-0ubuntu16
Architecture: amd64
Date: Tue Feb 4 23:31:52 2020
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
LANG=C.UTF-8
SHELL=/bin/bash
SourcePackage: linux-signed-5.4
UpgradeStatus: No upgrade log present (probably fresh install)
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