#! /bin/bash

test -x /sbin/btrfs || exit 0

export PATH=/usr/local/bin:$PATH

# bash shortcut for `basename $0`
PROG=${0##*/}
lock=/var/run/$PROG

# shlock (from inn) does the right thing and grabs a lock for a dead process
# (it checks the PID in the lock file and if it's not there, it
# updates the PID with the value given to -p)
if ! shlock -p $$ -f $lock; then
    echo "$lock held, quitting" >&2
    exit
fi

if which on_ac_power >/dev/null 2>&1; then
    ON_BATTERY=0
    on_ac_power >/dev/null 2>&1 || ON_BATTERY=$?
    if [ "$ON_BATTERY" -eq 1 ]; then
	exit 0
    fi
fi

for btrfs in $(grep btrfs /proc/mounts | awk '{ print $1 }' | sort -u)
do
    logger "Starting scrub of $btrfs"
    tail -n 0 -f /var/log/syslog | grep "BTRFS: " | grep -Ev '(disk space caching is enabled|unlinked .* orphans|turning on discard|device label .* devid .* transid|enabling SSD mode|BTRFS: has skinny extents|BTRFS: device label)' &
    /sbin/btrfs scrub start -Bd $btrfs
    pkill -f 'tail -n 0 -f /var/log/syslog'
    logger "Ended scrub of $btrfs"
done

rm $lock