[libvirt] [RFC v2 0/4] LXC with block device and enabled userns

Hi all, This patch series aims to resolve https://bugzilla.redhat.com/show_bug.cgi?id=1328946 For background information about the issue see v1 of this RFC. https://www.redhat.com/archives/libvir-list/2018-April/msg01270.html The current state of this series enables the start of LXC container with NBD file system and enabled user namespace. However, container shutdown causes "kernel BUG at fs/buffer.c:3058!" https://pastebin.com/raw/y0ycSM0H The reason for this is because qemu-nbd process is terminated/killed without unmounting the container root file system. This issue has been reported in [1] and [2]. [1] https://bugzilla.redhat.com/show_bug.cgi?id=1356110 [2] http://lkml.iu.edu/hypermail/linux/kernel/1509.3/00027.html As a workaround we could unmount the root file system of container before shutdown. For example with: $ CT_PID=$(pidof libvirt_lxc) $ sudo nsenter \ --mount=/proc/$CT_PID/task/$CT_PID/ns/mnt \ /bin/bash -c "umount /var/run/libvirt/lxc/guest.root/" I noticed that we already have the functions lxcContainerUnmountSubtree and virProcessRunInMountNamespace. Any suggestions on how to properly implement this? Thanks, Radostin Stoyanov (4): lxc: Make lxcContainerMountFSBlock non static lxc: Move up virLXCControllerAppendNBDPids lxc: Mount NBD devices before clone lxc: Remove unused lxcContainerPrepareRoot src/lxc/lxc_container.c | 58 +------------- src/lxc/lxc_container.h | 4 + src/lxc/lxc_controller.c | 158 +++++++++++++++++++++++---------------- 3 files changed, 97 insertions(+), 123 deletions(-) -- 2.17.1