#!/bin/bash
# blacklist-zfs.sh — ZFS is unused on the tsys Proxmox hosts (zero pools):
# keep the module and its service family out of RAM and out of boot. [#737]
# Run ON a Proxmox host: tests/remote.sh prox-file proxmox/perf/scripts/blacklist-zfs.sh
# Reversible: rm /etc/modprobe.d/blacklist-zfs.conf && systemctl enable zfs.target zfs-zed ...
set -u

log() { echo "[zfs-blacklist] $*"; }

# Guard: never touch a host whose root filesystem is ZFS.
root_fs=$(findmnt -n -o FSTYPE / 2>/dev/null)
case "$root_fs" in
    *zfs*) log "ABORT: root fs is '$root_fs' — this host needs ZFS at boot"; exit 1 ;;
esac

conf=/etc/modprobe.d/blacklist-zfs.conf
if [ ! -f "$conf" ]; then
    {
        echo "# ZFS unused on this host (no pools) — keep module out of RAM and boot [#737]"
        echo "blacklist zfs"
    } > "$conf"
    log "wrote $conf"
else
    log "blacklist already present"
fi

# Stop + disable the zfs service family (zed holds the module open; the
# import/mount/share units would fail or reload the module every boot).
systemctl disable --now \
    zfs-zed.service zfs-import-cache.service zfs-import-scan.service \
    zfs-import.target zfs-mount.service zfs-share.service \
    zfs-volume-wait.service zfs-volumes.target zfs.target >/dev/null 2>&1
log "zfs service family disabled"

if lsmod | grep -q '^zfs'; then
    if modprobe -r zfs 2>/dev/null; then
        log "module unloaded (ARC reclaimed)"
    else
        log "WARNING: module still in use — will stay away after next reboot anyway"
    fi
else
    log "module not loaded"
fi

# Bake the blacklist into the initramfs so early boot cannot load it either.
if command -v update-initramfs >/dev/null 2>&1; then
    if update-initramfs -u -k all >/dev/null 2>&1; then
        log "initramfs updated"
    else
        log "WARNING: update-initramfs failed — blacklist applies from main boot only"
    fi
fi

state=$(systemctl is-enabled zfs-zed 2>/dev/null)
log "done: root_fs=${root_fs:-?} zfs_zed=${state:-n/a} module=$(lsmod | grep -c '^zfs')"