#!/bin/sh
#
# Call fstrim on mounted partitions to maintain write performance.
# This is only relevant for SSD drives, see
# http://wiki.ubuntuusers.de/SSD/TRIM
set -e

# 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
else
HDPARM="`hdparm -I $REALDEV`" 2>/dev/null || continue
if [ -z "$NO_MODEL_CHECK" ]; then
if ! contains "$HDPARM" "Intel" && \
! contains "$HDPARM" "INTEL" && \
! contains "$HDPARM" "Samsung" && \
! contains "$HDPARM" "SAMSUNG" && \
! contains "$HDPARM" "OCZ" && \
! contains "$HDPARM" "SanDisk" && \
! contains "$HDPARM" "Patriot"; then
#echo "device $DEV is not a drive that is known-safe for trimming"
continue
fi
fi
if ! contains "$HDPARM" "TRIM"; then
#echo "device $DEV does not support trimming"
continue
fi
fi

if [ -n "$SILENT_FAILURE" ]; then
fstrim $MOUNT 2>/dev/null || true
else
fstrim $MOUNT
fi
done < /proc/mounts