#!/usr/bin/env bash

set -euo pipefail
shopt -s nullglob

THP_ENABLED_PATH="/sys/kernel/mm/transparent_hugepage/enabled"
THP_DEFRAG_PATH="/sys/kernel/mm/transparent_hugepage/defrag"
if [ -f "$THP_ENABLED_PATH" ]; then
  echo "Attempting to set THP enabled mode to 'madvise'..."
  if echo madvise > "$THP_ENABLED_PATH"; then
    echo "Successfully set THP enabled mode to madvise."
  else
    echo "ERROR: Failed to set THP enabled mode." >&2
  fi
else
  echo "WARNING: THP enabled file not found at $THP_ENABLED_PATH. THP may not be compiled into the kernel."
fi

if [ -f "$THP_DEFRAG_PATH" ]; then
  echo "Attempting to set THP defrag mode to 'madvise'..."
  if echo madvise > "$THP_DEFRAG_PATH"; then
    echo "Successfully set THP defrag mode to madvise."
  else
    echo "ERROR: Failed to set THP defrag mode." >&2
  fi
else
  echo "WARNING: THP defrag file not found at $THP_DEFRAG_PATH."
fi

echo "THP configuration script finished."

devices=(/dev/disk/by-id/nvme-{ALIBABA_NVMe_Controller,Ali_ECS_NVMe_Instance_Storage}_*)
((${#devices[@]} == 0)) && exit 0

vg_name="volumegroup1"
lv_name="local-storage"
mount_dir="/mnt/fast-disks"

vgcreate "$vg_name" "${devices[@]}"

# Use 90% of the VG by extents to avoid 512-byte alignment issues
lvcreate -l 90%VG -n "$lv_name" "$vg_name"

mkfs.ext4 "/dev/${vg_name}/${lv_name}"
mkdir -p "$mount_dir"
mountpoint -q "$mount_dir" || mount "/dev/${vg_name}/${lv_name}" "$mount_dir"

uuid=$(blkid -s UUID -o value "/dev/${vg_name}/${lv_name}")
if ! grep -q "UUID=${uuid}" /etc/fstab; then
  echo "UUID=${uuid} ${mount_dir} ext4 defaults,nofail,noatime,x-systemd.device-timeout=10s 0 0" >> /etc/fstab
fi
chmod 777 "$mount_dir"