SRU TEAM: Summary is the one above. The reason why Bionic SRU makes sense was discussed with @paelzer during merge review:
https://code.launchpad.net/~rafaeldtinoco/ubuntu/+source/bcache- tools/+git/bcache-tools/+merge/388774/comments/1022492 Thanks for reviewing the SRU. @rafaeldtinoco ** Description changed: + 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@ubuntu:~# lsb_release -rd Description: Ubuntu Focal Fossa (development branch) Release: 20.04 2. root@ubuntu:~# lsb_release -rd Description: Ubuntu Focal Fossa (development branch) Release: 20.04 root@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@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@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) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1861941 Title: bcache by-uuid links disappear after mounting bcache0 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/bcache-tools/+bug/1861941/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
