#!/bin/bash
#
# Call fstrim on mounted partitions to maintain write performance.
# This is only relevant for SSD drives, see
# http://wiki.ubuntuusers.de/SSD/TRIM
export PATH=usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:$PATH

set -e

declare -i interval=10
declare -i timeout=600
declare -i block_size=1073741824

function printUsage() {
    cat <<EOF

Synopsis
    $0 [-t timeout] [-i interval] [-b block size]
    Trim device per block, with interval.

    -t timeout
        Number of seconds to wait trim per device.
        Default value: $timeout seconds.

    -i interval
        Interval between trim next block.
        Default value: $interval seconds.

    -b block size
        lenght trim byte
        Default value: $block_size bytes.

EOF
}

# Options.
while getopts ":t:i:b:" option; do
    case "$option" in
        t) timeout=$OPTARG ;;
        i) interval=$OPTARG ;;
        b) block_size=$OPTARG ;;
        *) printUsage; exit 1 ;;
    esac
done
shift $((OPTIND - 1))

# needs /proc
[ -r /proc/mounts ] || exit 0

# these file systems support trimming
SUPPORTED_FS="ext3 ext4 xfs btrfs"

# arguments: <haystack> <needle>
contains() {
    [ "${1#*$2}" != "$1" ]
}

# As long as there are bugs like https://launchpad.net/bugs/1259829 we only run
# fstrim on Intel and Samsung drives; with --no-model-check it will run on all
# drives instead.
if [ "$1" = "--no-model-check" ]; then
    NO_MODEL_CHECK=1
fi

DONE=''
while read DEV MOUNT FSTYPE OPTIONS REST; do
    # only consider /dev/*
    [ "${DEV#/dev}" != "$DEV" ] || continue
    # ignore mounts with "discard", they TRIM already
    if contains "$OPTIONS" discard; then continue; fi
    # only consider supported file systems
    if ! contains "$SUPPORTED_FS" "$FSTYPE"; then continue; fi
    # ignore temporary devices which already went away
    [ -e "$DEV" ] || continue

    # did we see this already? we need to resolve symlinks
    # for/dev/disks/by-{label,uuid}, etc.; ignore if the device does not exist
    # any more
    REALDEV=`readlink -f $DEV` || continue
    if contains "$DONE" " $REALDEV "; then continue; fi
    DONE="$DONE $REALDEV "

    #echo "device $DEV real $REALDEV mountpoint $MOUNT fstype $FSTYPE"

    # check if that device supports trim; this does not work for devmapper or
    # mdadm, though, so just call fstrim on those without the extra check and
    # ignore errors; for cryptsetup and LVM you also need extra configuration
    # options to propagate discards, which the admin might have turned off
    unset SILENT_FAILURE
    if [ "${REALDEV#/dev/dm-}" != "$REALDEV" ]; then
        #echo "device $DEV is on devmapper, skipping TRIM feature check"
        SILENT_FAILURE=1
    elif [ "${REALDEV#/dev/md}" != "$REALDEV" ]; then
        #echo "device $DEV is on mdadm, skipping TRIM feature check"
        SILENT_FAILURE=1
    elif ! type hdparm >/dev/null 2>&1; then
        #echo "hdparm not available, cannot TRIM"
        exit 0
    fi

    lenght=$(df $REALDEV --block-size=$block_size | grep -v "blocks" | awk '{print $2}')
    fstrim_cmd="ionice -c 2 -n 7 nice -n 19 fstrim $MOUNT"
    dev_timeout=$timeout

#    echo $lenght

    for ((i=0; i<$lenght ; i++ ))
    do

      dev_timeout=$(bc <<< $dev_timeout-$interval)
      if (( dev_timeout < 0 ));then
         break
      fi

      offset=$(($i * $block_size))
      fstrim_arg="-o $offset -l $block_size"

      $fstrim_cmd $fstrim_arg 2>/dev/null || true

      sleep $interval

    done

done < /proc/mounts