'Failed to append name - rootfs' error while destroying container with btrfs storage

[aston-r]

Hi,

General Information:

cat /etc/redhat-release 
CentOS Linux release 7.6.1810 (Core) 

lxc-start --version
3.1.0

cat /proc/1/mounts | grep btrfs
/dev/nvme1n1p3 /var/lib/lxc btrfs rw,noatime,nodatasum,nodatacow,ssd,space_cache,subvolid=5,subvol=/ 0 0

STR:

• mkfs.btrfs /dev/nvme1n1p3 -f
• mount /dev/nvme1n1p3 /var/lib/lxc -o noatime,nodatacow
• lxc-create --name="btrfs" --bdev='btrfs' --template="download" -- --dist centos --release 7 --arch amd64

btrfs subvolume list  /var/lib/lxc/ | grep btrfs
ID 570 gen 1200 top level 5 path btrfs/rootfs

cat /var/lib/lxc/btrfs/config 
# Template used to create this container: /usr/share/lxc/templates/lxc-download
# Parameters passed to the template: --dist centos --release 7 --arch amd64
# For additional config options, please look at lxc.container.conf(5)

# Uncomment the following line to support nesting containers:
#lxc.include = /usr/share/lxc/config/nesting.conf
# (Be aware this has security implications)


# Distribution configuration
lxc.include = /usr/share/lxc/config/common.conf
lxc.arch = x86_64

# Container specific configuration
lxc.rootfs.path = btrfs:/var/lib/lxc/btrfs/rootfs
lxc.uts.name = btrfs

# Network configuration
lxc.net.0.type = veth
lxc.net.0.link = br-ex
lxc.net.0.flags = up
lxc.net.0.hwaddr = 00:16:3e:fe:b7:f4

• lxc-destroy -n btrfs

lxc-destroy -n btrfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs
lxc-destroy: btrfs: tools/lxc_destroy.c: main: 271 Destroyed container btrfs

[mullnerz]

The same happens also on Ubuntu 18.04...

uname -a
Linux test2 4.15.0-46-generic #49-Ubuntu SMP Wed Feb 6 09:33:07 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

cat /etc/issue.net 
Ubuntu 18.04.2 LTS

lxc-start --version
3.0.3

cat /proc/1/mounts | grep btrfs
/dev/md4 /var/lib/lxc btrfs rw,relatime,ssd,space_cache,subvolid=5,subvol=/ 0 0

lxc-destroy -n testbtrfs

lxc-destroy: master-vdmg-trading: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs���
lxc-destroy: master-vdmg-trading: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs���
lxc-destroy: master-vdmg-trading: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs���
lxc-destroy: master-vdmg-trading: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs���
lxc-destroy: master-vdmg-trading: storage/btrfs.c: get_btrfs_subvol_path: 103 Failed to append name - rootfs���
lxc-destroy: master-vdmg-trading: tools/lxc_destroy.c: main: 271 Destroyed container testbtrfs

[brauner]

Tracked it down and sent a branch that fixes it:
#2900

[visibilityspots]

@brauner is there a manual fix one can perform in the meantime while waiting on a release with the fix included?

[ceremcem]

Why is this issue closed, while it still exists in version 3.0.3 (on Debian Buster)?

[ceremcem]

Meanwhile anyone who encounters this issue can insert the following function into ~/.bash_aliases (or ~/.bashrc):

is_btrfs_subvolume() {
    sudo btrfs subvolume show "$1" >/dev/null 2>&1
}

lxc-destroy(){
    # See: https://github.com/lxc/lxc/issues/2826
    >&2 echo "I: Using lxc-destroy from bash_aliases."
    >&2 echo
    local name=$1
    [[ -n $name ]] || { echo "Container name is required"; return 1; }
    local path=/var/lib/lxc/$name
    [[ -d $path ]] || { echo "$path does not exist."; return 1; }
    echo "Removing $path"
    if [[ -d $path/rootfs ]]; then
        if is_btrfs_subvolume $path/rootfs; then
            sudo btrfs sub del $path/rootfs
        else
            sudo rm -r $path/rootfs
        fi
    fi
    sudo rm -r $path
    echo "Deleted $path"
}