#!/bin/sh -eu

# directly exit successfully when zfs module is not loaded
if ! [ -d /sys/module/zfs ]; then
	exit 0
fi

# [auto] / enable / disable
PROPERTY_NAME="org.debian:periodic-trim"

get_property () {
	# Detect the ${PROPERTY_NAME} property on a given pool.
	# We are abusing user-defined properties on the root dataset,
	# since they're not available on pools https://github.com/openzfs/zfs/pull/11680
	# TODO: use zpool user-defined property when such feature is available.
	pool="$1"
	zfs get -H -o value "${PROPERTY_NAME}" "${pool}" 2>/dev/null || return 1
}

trim_if_not_already_trimming () {
	pool="$1"
	if ! zpool status "${pool}" | grep -q "trimming"; then
		# Ignore errors (i.e. HDD pools),
		# and continue with trimming other pools.
		zpool trim "${pool}" || true
	fi
}

get_transp () {
        local dev="$1"
        local par_dev="$dev"
        local pd
        while true; do
                pd=$(lsblk -dnr -o PKNAME "$par_dev")
                if [ "$?" -ne 0 ]; then
                        return $?
                fi
                if [ -z "$pd" ]; then
                        break
                else
                        par_dev="/dev/$pd"
                fi
        done
        lsblk -dnr -o TRAN "$par_dev"
}

zpool_is_nvme_only () {
	zpool=$1
	# get a list of devices attached to the specified zpool
        for x in $(zpool list -vHPL "${zpool}" |\
            awk -F'\t' '{if($2 ~ /^\/dev\//) print $2}'); do
                if [ "$(get_transp $x)" != "nvme" ]; then
                        return 1
                fi
        done
}

# TRIM all healthy pools that are not already trimming as per their configs.
zpool list -H -o health,name 2>&1 | \
	awk -F'\t' '$1 == "ONLINE" {print $2}' | \
while read pool
do
	# read user-defined config
	ret=$(get_property "${pool}")
	if [ $? -ne 0 ] || [ "disable" = "${ret}" ]; then
		:
	elif [ "enable" = "${ret}" ]; then
		trim_if_not_already_trimming "${pool}"
	elif [ "-" = "${ret}" ] || [ "auto" = "${ret}" ]; then
		if zpool_is_nvme_only "${pool}"; then
			trim_if_not_already_trimming "${pool}"
		fi
	else
		cat > /dev/stderr <<EOF
$0: [WARNING] illegal value "${ret}" for property "${PROPERTY_NAME}" of ZFS dataset "${pool}".
$0: Acceptable choices for this property are: auto, enable, disable. The default is auto.
EOF
	fi
done