#! /bin/sh

# start or stop laptop_mode, best run by a power management daemon when
# ac gets connected/disconnected from a laptop
#
# install as /sbin/laptop_mode
#
# Contributors to this script:   Kiko Piris
#				 Bart Samwel
#				 Micha Feigin
#				 Andrew Morton
#				 Dax Kelson
#
# Original Linux 2.4 version by: Jens Axboe

# Remove an option (the first parameter) of the form option=<number> from
# a mount options string (the rest of the parameters).
parse_mount_opts () {
	OPT="$1"
	shift
	echo "$*"			| \
	sed 's/.*/,&,/'			| \
	sed 's/,'"$OPT"'=[0-9]*,/,/g'	| \
	sed 's/,,*/,/g'			| \
	sed 's/^,//'			| \
	sed 's/,$//'			| \
	cat -
}

# Remove an option (the first parameter) without any arguments from
# a mount option string (the rest of the parameters).
parse_nonumber_mount_opts () {
	OPT="$1"
	shift
	echo "$*" 			| \
	sed 's/.*/,&,/'			| \
	sed 's/,'"$OPT"',/,/g'		| \
	sed 's/,,*/,/g'			| \
	sed 's/^,//'			| \
	sed 's/,$//'			| \
	cat -
}

# Find out the state of a yes/no option (e.g. "atime"/"noatime") in
# fstab for a given filesystem, and use this state to replace the
# value of the option in another mount options string. The device
# is the first argument, the option name the second, and the default
# value the third. The remainder is the mount options string.
#
# Example:
# parse_yesno_opts_wfstab /dev/hda1 atime atime defaults,noatime
#
# If fstab contains, say, "rw" for this filesystem, then the result
# will be "defaults,atime".
parse_yesno_opts_wfstab () {
	L_DEV=$1
	shift
	OPT=$1
	shift
	DEF_OPT=$1
	shift
	L_OPTS="$*"
	PARSEDOPTS1="$(parse_nonumber_mount_opts $OPT $L_OPTS)"
	PARSEDOPTS1="$(parse_nonumber_mount_opts no$OPT $PARSEDOPTS1)"
	# Watch for a default atime in fstab
	FSTAB_OPTS="$(cat /etc/fstab | sed 's/  / /g' | grep ^\ *"$L_DEV " | awk '{ print $4 }')"
	if [ -z "$(echo "$FSTAB_OPTS" | grep "$OPT")" ] ; then
		# option not specified in fstab -- choose the default.
		echo "$PARSEDOPTS1,$DEF_OPT"
	else
		# option specified in fstab: extract the value and use it
		if [ -z "$(echo "$FSTAB_OPTS" | grep "no$OPT")" ] ; then
			# no$OPT not found -- so we must have $OPT.
			echo "$PARSEDOPTS1,$OPT"
		else
			echo "$PARSEDOPTS1,no$OPT"
		fi
	fi
}

# Find out the state of a numbered option (e.g. "commit=NNN") in
# fstab for a given filesystem, and use this state to replace the
# value of the option in another mount options string. The device
# is the first argument, and the option name the second. The
# remainder is the mount options string in which the replacement
# must be done.
#
# Example:
# parse_mount_opts_wfstab /dev/hda1 commit defaults,commit=7
#
# If fstab contains, say, "commit=3,rw" for this filesystem, then the
# result will be "rw,commit=3".
parse_mount_opts_wfstab () {
	L_DEV=$1
	shift
	OPT=$1
	shift
	L_OPTS="$*"

	PARSEDOPTS1="$(parse_mount_opts $OPT $L_OPTS)"
	# Watch for a default commit in fstab
	FSTAB_OPTS="$(cat /etc/fstab | sed 's/	/ /g' | grep ^\ *"$L_DEV " | awk '{ print $4 }')"
	if [ -z "$(echo "$FSTAB_OPTS" | grep "$OPT=")" ] ; then
		# option not specified in fstab: set it to 0
		echo "$PARSEDOPTS1,$OPT=0"
	else
		# option specified in fstab: extract the value, and use it
		echo -n "$PARSEDOPTS1,$OPT="
		echo "$FSTAB_OPTS"	| \
		sed 's/.*/,&,/'		| \
		sed 's/.*,'"$OPT"'=//'	| \
		sed 's/,.*//'		| \
		cat -
	fi
}

KLEVEL="$(uname -r | cut -c1-3)"
case "$KLEVEL" in
	"2.4"|"2.6")
		true
		;;
	*)
		echo "Unhandled kernel version: $KLEVEL ('uname -r' = '$(uname -r)')"
		exit 1
		;;
esac

# Shall we remount journaled fs. with appropiate commit interval? (1=yes)
DO_REMOUNTS=1

# age time, in seconds. should be put into a sysconfig file
MAX_AGE=600

# Dirty synchronous ratio.  At this percentage of dirty pages the process which
# calls write() does its own writeback
DIRTY_RATIO=40

#
# Allowed dirty background ratio, in percent.  Once DIRTY_RATIO has been
# exceeded, the kernel will wake pdflush which will then reduce the amount
# of dirty memory to dirty_background_ratio.  Set this nice and low, so once
# some writeout has commenced, we do a lot of it.
#
DIRTY_BACKGROUND_RATIO=5

READAHEAD=4096		# kilobytes

# kernel default dirty buffer age
DEF_AGE=30
DEF_UPDATE=5
DEF_DIRTY_BACKGROUND_RATIO=10
DEF_DIRTY_RATIO=40
DEF_XFS_AGE_BUFFER=15
DEF_XFS_SYNC_INTERVAL=30

# This must be adjusted manually to the value of HZ in the running kernel,
# until the XFS people change their external interfaces to work in centisecs
# like the rest of the external world. Unfortunately this cannot be automated. :(
XFS_HZ=100

if [ ! -e /proc/sys/vm/laptop_mode ]; then
	echo "Kernel is not patched with laptop_mode patch."
	exit 1
fi

if [ ! -w /proc/sys/vm/laptop_mode ]; then
	echo "You do not have enough privileges to enable laptop_mode."
	exit 1
fi

case "$1" in
	start)
		AGE=$((100*$MAX_AGE))
		XFS_AGE=$(($XFS_HZ*$MAX_AGE))
		echo -n "Starting laptop_mode"

		if [ -d /proc/sys/vm/pagebuf ] ; then
			# This only needs to be set, not reset -- it is only used when
			# laptop mode is enabled.
			echo $XFS_AGE > /proc/sys/vm/pagebuf/lm_flush_age
			echo $XFS_AGE > /proc/sys/fs/xfs/lm_sync_interval
		elif [ -f /proc/sys/fs/xfs/lm_age_buffer ] ; then
			# The same goes for these.
			echo $XFS_AGE > /proc/sys/fs/xfs/lm_age_buffer
			echo $XFS_AGE > /proc/sys/fs/xfs/lm_sync_interval
		elif [ -f /proc/sys/fs/xfs/age_buffer ] ; then
			# But not for these -- they are also used in normal
			# operation.
			echo $XFS_AGE > /proc/sys/fs/xfs/age_buffer
			echo $XFS_AGE > /proc/sys/fs/xfs/sync_interval
		fi

		case "$KLEVEL" in
			"2.4")
				echo "1"				> /proc/sys/vm/laptop_mode
				echo "30 500 0 0 $AGE $AGE 60 20 0"	> /proc/sys/vm/bdflush
				;;
			"2.6")
				echo "5"				> /proc/sys/vm/laptop_mode
				echo "$AGE"				> /proc/sys/vm/dirty_writeback_centisecs
				echo "$AGE"				> /proc/sys/vm/dirty_expire_centisecs
				echo "$DIRTY_RATIO"			> /proc/sys/vm/dirty_ratio
				echo "$DIRTY_BACKGROUND_RATIO"		> /proc/sys/vm/dirty_background_ratio
				;;
		esac
		if [ $DO_REMOUNTS -eq 1 ]; then
			cat /etc/mtab | while read DEV MP FST OPTS DUMP PASS ; do
				PARSEDOPTS="$(parse_mount_opts "$OPTS")"
				case "$FST" in
					"ext3"|"reiserfs")
						PARSEDOPTS="$(parse_mount_opts commit "$OPTS")"
						mount $DEV -t $FST $MP -o remount,$PARSEDOPTS,commit=$MAX_AGE,noatime
						;;
					"xfs")
						mount $DEV -t $FST $MP -o remount,$OPTS,noatime
						;;
				esac
				if [ -b $DEV ] ; then
					blockdev --setra $(($READAHEAD * 2)) $DEV
				fi
			done
		fi
		echo "."
		;;
	stop)
		U_AGE=$((100*$DEF_UPDATE))
		B_AGE=$((100*$DEF_AGE))
		echo -n "Stopping laptop_mode"
		echo "0" > /proc/sys/vm/laptop_mode
		if [ -f /proc/sys/fs/xfs/age_buffer ] && [ ! -f /proc/sys/fs/xfs/lm_age_buffer ] ; then
			# These need to be restored though, if there are no lm_*.
			echo "$(($XFS_HZ*$DEF_XFS_AGE_BUFFER))" 	> /proc/sys/fs/xfs/age_buffer
			echo "$(($XFS_HZ*$DEF_XFS_SYNC_INTERVAL))" 	> /proc/sys/fs/xfs/sync_interval
		fi
		case "$KLEVEL" in
			"2.4")
				echo "30 500 0 0 $U_AGE $B_AGE 60 20 0"	> /proc/sys/vm/bdflush
				;;
			"2.6")
				echo "$U_AGE"				> /proc/sys/vm/dirty_writeback_centisecs
				echo "$B_AGE"				> /proc/sys/vm/dirty_expire_centisecs
				echo "$DEF_DIRTY_RATIO"			> /proc/sys/vm/dirty_ratio
				echo "$DEF_DIRTY_BACKGROUND_RATIO"	> /proc/sys/vm/dirty_background_ratio
				;;
		esac
		if [ $DO_REMOUNTS -eq 1 ]; then
			cat /etc/mtab | while read DEV MP FST OPTS DUMP PASS ; do
				# Reset commit and atime options to defaults.
				case "$FST" in
					"ext3"|"reiserfs")
						PARSEDOPTS="$(parse_mount_opts_wfstab $DEV commit $OPTS)"
						PARSEDOPTS="$(parse_yesno_opts_wfstab $DEV atime atime $PARSEDOPTS)"
						mount $DEV -t $FST $MP -o remount,$PARSEDOPTS
						;;
					"xfs")
						PARSEDOPTS="$(parse_yesno_opts_wfstab $DEV atime atime $OPTS)"
						mount $DEV -t $FST $MP -o remount,$PARSEDOPTS
						;;
				esac
				if [ -b $DEV ] ; then
					blockdev --setra 256 $DEV
				fi
			done
		fi
		echo "."
		;;
	*)
		echo "Usage: $0 {start|stop}"
		;;

esac

exit 0