See: https://github.com/lxc/lxd/issues/4656#issuecomment-535531229
In https://github.com/lxc/lxd/blob/master/lxd/storage_zfs_utils.go#L255 the umount is done by err := unix.Unmount(mountpoint, unix.MNT_DETACH) The umount2(2) manpage writes about MNT_DETACH: Perform a lazy unmount: make the mount point unavailable for new accesses, immediately disconnect the filesystem and all filesystems mounted below it from each other and from the mount table, and actually perform the unmount when the mount point ceases to be busy. Could this be it? The MNT_DETACH umount looks partially asynchronous. All the subsequent destroy commands may fail because they keep the mount point busy. Finally the retry loop ends, the umount happens for real and the following destroy succeeds. — -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1779156 Title: lxc 'delete' fails to destroy ZFS filesystem 'dataset is busy' Status in linux package in Ubuntu: Triaged Status in lxc package in Ubuntu: Confirmed Status in linux source package in Cosmic: Triaged Status in lxc source package in Cosmic: Confirmed Status in linux source package in Disco: New Status in lxc source package in Disco: New Status in linux source package in Eoan: Triaged Status in lxc source package in Eoan: Confirmed Bug description: I'm not sure exactly what got me into this state, but I have several lxc containers that cannot be deleted. $ lxc info <snip> api_status: stable api_version: "1.0" auth: trusted public: false auth_methods: - tls environment: addresses: [] architectures: - x86_64 - i686 certificate: | -----BEGIN CERTIFICATE----- <snip> -----END CERTIFICATE----- certificate_fingerprint: 3af6f8b8233c5d9e898590a9486ded5c0bec045488384f30ea921afce51f75cb driver: lxc driver_version: 3.0.1 kernel: Linux kernel_architecture: x86_64 kernel_version: 4.15.0-23-generic server: lxd server_pid: 15123 server_version: "3.2" storage: zfs storage_version: 0.7.5-1ubuntu15 server_clustered: false server_name: milhouse $ lxc delete --force b1 Error: Failed to destroy ZFS filesystem: cannot destroy 'default/containers/b1': dataset is busy Talking in #lxc-dev, stgraber and sforeshee provided diagnosis: | short version is that something unshared a mount namespace causing | them to get a copy of the mount table at the time that dataset was | mounted, which then prevents zfs from being able to destroy it) The work around provided was | you can unstick this particular issue by doing: | grep default/containers/b1 /proc/*/mountinfo | then for any of the hits, do: | nsenter -t PID -m -- umount /var/snap/lxd/common/lxd/storage-pools/default/containers/b1 | then try the delete again ProblemType: Bug DistroRelease: Ubuntu 18.10 Package: linux-image-4.15.0-23-generic 4.15.0-23.25 ProcVersionSignature: Ubuntu 4.15.0-23.25-generic 4.15.18 Uname: Linux 4.15.0-23-generic x86_64 NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair ApportVersion: 2.20.10-0ubuntu3 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: smoser 31412 F.... pulseaudio /dev/snd/controlC2: smoser 31412 F.... pulseaudio /dev/snd/controlC0: smoser 31412 F.... pulseaudio CurrentDesktop: ubuntu:GNOME Date: Thu Jun 28 10:42:45 2018 EcryptfsInUse: Yes InstallationDate: Installed on 2015-07-23 (1071 days ago) InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Alpha amd64 (20150722.1) MachineType: b'\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff' b'\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff' ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-23-generic root=UUID=f897b32a-eacf-4191-9717-844918947069 ro quiet splash vt.handoff=1 RelatedPackageVersions: linux-restricted-modules-4.15.0-23-generic N/A linux-backports-modules-4.15.0-23-generic N/A linux-firmware 1.174 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 03/09/2015 dmi.bios.vendor: Intel Corporation dmi.bios.version: RYBDWi35.86A.0246.2015.0309.1355 dmi.board.asset.tag: ��������������������������������� dmi.board.name: NUC5i5RYB dmi.board.vendor: Intel Corporation dmi.board.version: H40999-503 dmi.chassis.asset.tag: ��������������������������������� dmi.chassis.type: 3 dmi.chassis.vendor: ��������������������������������� dmi.chassis.version: ��������������������������������� dmi.modalias: dmi:bvnIntelCorporation:bvrRYBDWi35.86A.0246.2015.0309.1355:bd03/09/2015:svn:pn:pvr:rvnIntelCorporation:rnNUC5i5RYB:rvrH40999-503:cvn:ct3:cvr: dmi.product.family: ��������������������������������� dmi.product.name: ��������������������������������� dmi.product.version: ��������������������������������� dmi.sys.vendor: ��������������������������������� To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1779156/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
