ZFS root systemd generator

zfs-root-fs-generator.sh

#!/bin/sh

generator_dir="$1"

list_datasets() {
    /usr/sbin/zfs list -r -H -o name,canmount,mountpoint "$1"
}

get_root_zfs_dataset() {
    while read mnt_dev mnt_path mnt_type rest; do
        if [ "$mnt_path" = "/" ] && [ "$mnt_type" = "zfs" ]; then
            echo "$mnt_dev"
            return 0
        fi
    done < /proc/self/mounts

    return 1
}

root_dataset=$(get_root_zfs_dataset)
if [ $? -ne 0 ] || [ -z "$root_dataset" ]; then
    exit 0
fi

echo "zfs-root-fs-generator: found root dataset $root_dataset" >> /dev/kmsg

list_datasets "${root_dataset%%/*}" | {
    while IFS=$(printf '\t') read dataset canmount mountpoint; do
        if ! [ "$canmount" = on ] || [ "$mountpoint" = legacy ] || [ "$mountpoint" = none ]; then
            continue
        fi

        unit_name=$(systemd-escape -p "$mountpoint")
        echo "zfs-root-fs-generator: adding $dataset -> ${unit_name}.mount" >> /dev/kmsg

        cat > "${generator_dir}/${unit_name}.mount" <<EOF
# Automatically generated by zfs-root-fs-generator

[Unit]
After=zfs-import-scan.service
After=zfs-import-cache.service
Before=local-fs.target

[Mount]
What=$dataset
Where=$mountpoint
Type=zfs
Options=zfsutil
EOF
        mkdir -p "$generator_dir/local-fs.target.requires"
        (cd "$generator_dir/local-fs.target.requires"; ln -s "../${unit_name}.mount" "${unit_name}.mount")
    done
}