** Description changed: === Begin SRU Template === [Impact] The 16.10 kernel dropped a legacy kernel module alias that allowed usage of the 'overlay' filesystem via name 'overlayfs'. This broke overlayroot as it explicitly tried to to use 'overlayfs' by name in loading of modules and also in entry in /etc/fstab. Without this fix, overlayroot will simply not work on any upstream kernel or Ubuntu kernel of 16.10 (yakkety) or later. [Test Case] Note, not applying proposed as shown in step 3 below will recreate failure. 1.) Start an instance of a cloud image. 2.) get a suitable 4.8 kernel On 16.10 or later, this is already done. On 16.04, we currently need to install the kernel team's PPA to get one. $ sudo apt-add-repository -y ppa:canonical-kernel-team/ppa $ sudo apt update -q && sudo apt install -y linux-virtual-hwe-16.04-edge </dev/null 3.) Enable proposed and install overlayroot to show fix. $ rel=$(lsb_release -sc) $ echo "deb http://archive.ubuntu.com/ubuntu $rel-proposed main" | $ sudo tee /etc/apt/sources.list.d/proposed.list $ sudo apt update -qy && sudo apt install -qy overlayroot </dev/null $ dpkg-query --show overlayroot overlayroot 0.27ubuntu1.3 4.) Enable overlayroot and reboot - # remove the cloud-init written mount options for /dev/vdb - # if we do not do this, then /mnt ends up not mounted due to ordering. - $ sudo sed -i.dist s/,x-systemd.requires=cloud-init.service,comment=cloudconfig// /etc/fstab + # remove the cloud-init written mount options for /dev/vdb + # if we do not do this, then /mnt ends up not mounted due to ordering. + $ sudo sed -i.dist s/,x-systemd.requires=cloud-init.service,comment=cloudconfig// /etc/fstab $ echo "overlayroot=tmpfs" | sudo tee /etc/overlayroot.local.conf $ sudo reboot 5.) log back in and look around. a.) check that 'overlayroot' is in /proc/mounts $ awk '$1 == "overlayroot" { print $0 }' /proc/mounts overlayroot / overlay rw,relatime,lowerdir=/media/root-ro,upperdir=/media/root-rw/overlay,workdir=/media/root-rw/overlay-workdir/_ 0 0 b.) check /run/initramfs/overlayroot.log $ grep success /run/initramfs/overlayroot.log [success]: configured root with 'tmpfs' using overlay per /dev/vda1/etc/overlayroot.local.conf 6.) try with recurse disabled Assuming you're on the same system and in an overlayroot, to change the file necessary, we use overlayroot-chroot. $ echo overlayroot=tmpfs:recurse=0 | sudo overlayroot-chroot tee /etc/overlayroot.local.conf $ sudo reboot 7.) log back in and look around. This time the /mnt should not have overlay on it. - $ grep vdb /proc/mounts - /dev/vdb /mnt ext4 rw,relatime,data=ordered 0 0 - $ grep overlay /proc/mounts - overlayroot / overlay rw,relatime,lowerdir=/media/root-ro,upperdir=/media/root-rw/overlay,workdir=/media/root-rw/overlay-workdir/_ 0 0 - $ cat /etc/overlayroot.local.conf - overlayroot=tmpfs:recurse=0 - + $ grep vdb /proc/mounts + /dev/vdb /mnt ext4 rw,relatime,data=ordered 0 0 + $ grep overlay /proc/mounts + overlayroot / overlay rw,relatime,lowerdir=/media/root-ro,upperdir=/media/root-rw/overlay,workdir=/media/root-rw/overlay-workdir/_ 0 0 + $ cat /etc/overlayroot.local.conf + overlayroot=tmpfs:recurse=0 [Regression Potential] The most likely regression is just in failure for overlayroot to work. That was the case 100% of the time on any kernel without 'overlayfs' filesystem, so this can't really make things worse from that perspective. Some of the code change was related to fixing another issue, with 'recurse'. Testing recurse (where not just / is mounted as an overlayroot) is done above echo overlayroot=tmpfs:recurse=1 | sudo overlayroot-chroot tee /etc/overlayroot.local.conf [Other Info] The full overlayroot/init-bottom/overlayroot can be seen at [1]. The specific change that fixed the issue is in revision 115 at [2]. + Related bugs: + * bug 1630274 adjusted the mechanism for determining if overlay was supported. + The change to do so is included in the xenial backport for this bug. + [1] http://bazaar.launchpad.net/~cloud-initramfs-tools/cloud-initramfs-tools/trunk/view/head:/overlayroot/scripts/init-bottom/overlayroot [2] http://bazaar.launchpad.net/~cloud-initramfs-tools/cloud-initramfs-tools/trunk/revision/115 === End SRU Template === As mentioned in LP: #1411294, it's now called 'overlay' instead of 'overlayfs'. Ubuntu had patched the kernel for compatibility. The Ubuntu kernels as of 4.8 (16.10 kernel) and possibly a bit before no longer have a overlayfs module either. Thus, this is now affecting yakkety. (The original reporter is @~gpo-9.)
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1493188 Title: "overlayfs" no longer exists To manage notifications about this bug go to: https://bugs.launchpad.net/cloud-initramfs-tools/+bug/1493188/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
