various updates

[distro-setup] / btrfsmaint

#!/bin/bash


[[ $EUID == 0 ]] || exec sudo -E "${BASH_SOURCE[0]}" "$@"

source /a/bin/errhandle/err

# inspired from
# https://github.com/kdave/btrfsmaintenance


# Man page says we could also use a range, i suppose it would be
# logical to use a pattern like 5..10 10..20,
# but I don't know if this would help us at all.
dusage="5 10"
musage="5"

e() {
  echo "cron: $*"
  if ! $dryrun; then
    "$@"
  fi
}

check-idle() {
  type -p xprintidle &>/dev/null || return 0
  export DISPLAY=:0
  # a hours, a movie could run that long.
  idle_limit=$((1000 * 60 * 60 * 2))
  idle_time=$idle_limit
  while read -r user; do
    new_idle_time=$(sudo -u $user xprintidle 2>/dev/null) ||:
    if [[ $new_idle_time && $new_idle_time -lt $idle_time ]]; then
      idle_time=$new_idle_time
    fi
  done < <(users | tr " " "\n" | sort -u)
  if (( idle_time < idle_limit )); then
    idle=false
  else
    idle=true
  fi
}

usage() {
  cat <<EOF
Usage: ${0##*/} [ARGS]
Do btrfs maintence or stop if xprintidle shows a user

force  Run regardless of user idle status on all disks and do scrub
       regardless of when it was last run.
check  Only check if an existing maintence should be cancelled due to
         nonidle user. Also, runs in a loop every 20 seconds for 10
         minutes.

Note: Uses util-linux getopt option parsing: spaces between args and
options, short options can be combined, options before args.
EOF
  exit $1
}


force=false
check=false
dryrun=false
if [[ $1 ]]; then
  case $1 in
    check)
      check=true
      ;;
    force)
      force=true
      ;;
    dryrun)
      dryrun=true
      ;;
    *)
      echo "$0: error: unexpected arg" >&2
      usage 1
      ;;
  esac
fi


main() {
  idle=true
  if ! $force; then
    check-idle
    if ! $check; then
      min=0
      max_min=300
      # When the cron kicks in, we may not be idle (physically sleeping) yet, so
      # wait.
      while ! $idle && (( min < max_min )); do
        min=$(( min + 1 ))
        sleep 60
        check-idle
      done
      # If we've waited a really long time for idle, just give up.
      if (( min == max_min )); then
        return
      fi
    fi
  fi


  fnd="findmnt --types btrfs --noheading"
  for x in $($fnd --output "SOURCE" --nofsroot | sort -u); do
    mnt=$($fnd --output "TARGET" --first-only --source $x)
    [[ $mnt ]] || continue

    #### begin look for diff in stats, eg: increasing error count ####

    # Only run for $check, since it runs in parallel to non-check, avoid
    # race condition.
    if $check; then
      tmp=$(mktemp)
      # if mnt is /, avoid making a buggy looking path
      stats_path=${mnt%/}/btrfs-dev-stats
      if [[ ! -e $stats_path ]]; then
        btrfs dev stats -c $mnt >$stats_path ||: # populate initial reading
      elif ! btrfs dev stats -c $mnt >$tmp; then
        if ! diff -q $stats_path $tmp; then
              exim -t <<EOF
From: root@$HOSTNAME.b8.nz
To: alerts@iankelling.org
Subject: btrfsmaintstop: btrfs dev stats -c $mnt

$(diff -u $stats_path $tmp ||:)
EOF
          mv $stats_path $stats_path.1
          cat $tmp >$stats_path
        fi
      fi
      rm -f $tmp
    fi
    #### end look for diff in stats, eg: increasing error count ####

    if $check; then
      if ! $idle; then
        if $dryrun; then
          echo "$0: not idle. if this wasnt a dry run, btrfs scrub cancel $mnt"
        else
          btrfs scrub cancel $mnt &>/dev/null ||:
        fi
      fi
      continue
    fi

    # for comparing before and after balance.
    # the log is already fairly verbose, so commented.
    # e btrfs filesystem df $mnt
    # e df -H $mnt
    if btrfs filesystem df $mnt | grep -q "Data+Metadata"; then
      for usage in $dusage; do
        e ionice -c 3 btrfs balance start -dusage=$usage -musage=$usage $mnt
      done
    else
      e ionice -c 3 btrfs balance start -dusage=0 $mnt
      for usage in $dusage; do
        e ionice -c 3 btrfs balance start -dusage=$usage $mnt
      done
      e ionice -c 3 btrfs balance start -musage=0 $mnt
      for usage in $musage; do
        e ionice -c 3 btrfs balance start -musage=$usage $mnt
      done
    fi
    date=
    scrub_status=$(btrfs scrub status $mnt)
    if printf "%s\n" "$scrub_status" | grep -i '^status:[[:space:]]*finished$' &>/dev/null; then
      date=$(printf "%s\n" "$scrub_status" | sed -rn 's/^Scrub started:[[:space:]]*(.*)/\1/p')
    fi
    if [[ ! $date ]]; then
      # output from older versions, at least btrfs v4.15.1
      date=$(
        printf "%s\n" "$scrub_status" | \
          sed -rn 's/^\s*scrub started at (.*) and finished.*/\1/p'
          )
    fi
    if ! $force && [[ $date ]]; then
      if $dryrun; then
        echo "$0: last scrub finish for $mnt: $date"
      fi
      date=$(date --date="$date" +%s)
      # if date is sooner than 60 days ago
      # the wiki recommends 30 days or so, but
      # I'm going with 60 days.
      if (( date > EPOCHSECONDS - 60*60*24*60 )); then
        if $dryrun; then
          echo "$0: skiping scrub of $mnt, last was $(( (EPOCHSECONDS - date) / 60/60/24 )) days ago, < 30 days"
        fi
        continue
      fi
    fi
    # btrfsmaintenance does -c 2 -n 4, but I want lowest pri.
    e btrfs scrub start -Bd -c 3 $mnt

    # We normally only do one disk since this is meant to be run while I sleep
    # and if we try to do all disks, we invariably end up doing a scrub still
    # after I've woken up. So, just do one per day.
    if ! $force; then
      return 0
    fi
  done
}

loop-main() {
  while true; do
    main
    sleep 60
  done
}

if $check; then
  loop-main
else
  main
fi