[PATCH] Laptop mode control script improvements

From: Herve Eychenne <rv@eychenne.org>

Clean up the script. This also makes it two times faster. (Thanks to
Herve Eychenne.)

- moved variable definitions to the top, for easier configuration
- the script contains bashisms, so make it /bin/bash
- use sed -e'...' -e '...' instead of sed | sed 
- avoid subshells: () changed to {}
- various other minor optimizations and improvements
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/laptop-mode.txt

@@ -165,7 +165,7 @@ Control script
 Please note that this control script works for the Linux 2.4 and 2.6 series.
 
 --------------------CONTROL SCRIPT BEGIN------------------------------------------
-#! /bin/sh
+#!/bin/bash
 
 # start or stop laptop_mode, best run by a power management daemon when
 # ac gets connected/disconnected from a laptop
@@ -176,22 +176,91 @@ Please note that this control script works for the Linux 2.4 and 2.6 series.
 #				 Bart Samwel
 #				 Micha Feigin
 #				 Andrew Morton
+#				 Herve Eychenne
 #				 Dax Kelson
 #
 # Original Linux 2.4 version by: Jens Axboe
 
+#############################################################################
+
+# Age time, in seconds. should be put into a sysconfig file
+MAX_AGE=600
+
+# Read-ahead, in kilobytes
+READAHEAD=4096
+
+# Shall we remount journaled fs. with appropiate commit interval? (1=yes)
+DO_REMOUNTS=1
+
+# And shall we add the "noatime" option to that as well? (1=yes)
+DO_REMOUNT_NOATIME=1
+
+# 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
+
+# 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
+DEF_XFS_BUFD_INTERVAL=1
+
+# This must be adjusted manually to the value of HZ in the running kernel
+# on 2.4, until the XFS people change their 2.4 external interfaces to work in
+# centisecs. This can be automated, but it's a work in progress that still needs
+# some fixes. On 2.6 kernels, XFS uses USER_HZ instead of HZ for external
+# interfaces, and that is currently always set to 100. So you don't need to
+# change this on 2.6.
+XFS_HZ=100
+
+#############################################################################
+
+KLEVEL="$(uname -r |
+             {
+	       IFS='.' read a b c
+	       echo $a.$b
+	     }
+)"
+case "$KLEVEL" in
+	"2.4"|"2.6")
+		;;
+	*)
+		echo "Unhandled kernel version: $KLEVEL ('uname -r' = '$(uname -r)')" >&2
+		exit 1
+		;;
+esac
+
+if [ ! -e /proc/sys/vm/laptop_mode ] ; then
+	echo "Kernel is not patched with laptop_mode patch." >&2
+	exit 1
+fi
+
+if [ ! -w /proc/sys/vm/laptop_mode ] ; then
+	echo "You do not have enough privileges to enable laptop_mode." >&2
+	exit 1
+fi
+
 # 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 -
+	echo ",$*," | sed		\
+	 -e 's/,'"$OPT"'=[0-9]*,/,/g'	\
+	 -e 's/,,*/,/g'			\
+	 -e 's/^,//'			\
+	 -e 's/,$//'
 }
 
 # Remove an option (the first parameter) without any arguments from
@@ -199,13 +268,11 @@ parse_mount_opts () {
 parse_nonumber_mount_opts () {
 	OPT="$1"
 	shift
-	echo "$*" 			| \
-	sed 's/.*/,&,/'			| \
-	sed 's/,'"$OPT"',/,/g'		| \
-	sed 's/,,*/,/g'			| \
-	sed 's/^,//'			| \
-	sed 's/,$//'			| \
-	cat -
+	echo ",$*," | sed		\
+	 -e 's/,'"$OPT"',/,/g'		\
+	 -e 's/,,*/,/g'			\
+	 -e 's/^,//'			\
+	 -e 's/,$//'
 }
 
 # Find out the state of a yes/no option (e.g. "atime"/"noatime") in
@@ -220,28 +287,26 @@ parse_nonumber_mount_opts () {
 # 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_DEV="$1"
+	OPT="$2"
+	DEF_OPT="$3"
+	shift 3
 	L_OPTS="$*"
 	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
+	FSTAB_OPTS="$(awk '$1 == "'$L_DEV'" { print $4 }' /etc/fstab)"
+	if echo "$FSTAB_OPTS" | grep "$OPT" > /dev/null ; then
 		# option specified in fstab: extract the value and use it
-		if [ -z "$(echo "$FSTAB_OPTS" | grep "no$OPT")" ] ; then
+		if echo "$FSTAB_OPTS" | grep "no$OPT" > /dev/null ; then
+			echo "$PARSEDOPTS1,no$OPT"
+		else
 			# no$OPT not found -- so we must have $OPT.
 			echo "$PARSEDOPTS1,$OPT"
-		else
-			echo "$PARSEDOPTS1,no$OPT"
 		fi
+	else
+		# option not specified in fstab -- choose the default.
+		echo "$PARSEDOPTS1,$DEF_OPT"
 	fi
 }
 
@@ -258,97 +323,27 @@ parse_yesno_opts_wfstab () {
 # 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_DEV="$1"
+	OPT="$2"
+	shift 2
 	L_OPTS="$*"
-
 	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
+	FSTAB_OPTS="$(awk '$1 == "'$L_DEV'" { print $4 }' /etc/fstab)"
+	if echo "$FSTAB_OPTS" | grep "$OPT=" > /dev/null ; then
 		# option specified in fstab: extract the value, and use it
 		echo -n "$PARSEDOPTS1,$OPT="
-		echo "$FSTAB_OPTS"	| \
-		sed 's/.*/,&,/'		| \
-		sed 's/.*,'"$OPT"'=//'	| \
-		sed 's/,.*//'		| \
-		cat -
+		echo ",$FSTAB_OPTS," | sed \
+		 -e 's/.*,'"$OPT"'=//'	\
+		 -e 's/,.*//'
+	else
+		# option not specified in fstab: set it to 0
+		echo "$PARSEDOPTS1,$OPT=0"
 	fi
 }
 
-KLEVEL=$(
-           uname -r |
-             (
-	       IFS="." read a b c
-	       echo $a.$b
-	     )
-	 )
-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
-
-# And shall we add the "noatime" option to that as well? (1=yes)
-DO_REMOUNT_NOATIME=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
-DEF_XFS_BUFD_INTERVAL=1
-
-# This must be adjusted manually to the value of HZ in the running kernel
-# on 2.4, until the XFS people change their 2.4 external interfaces to work in
-# centisecs. This can be automated, but it's a work in progress that still needs
-# some fixes. On 2.6 kernels, XFS uses USER_HZ instead of HZ for external
-# interfaces, and that is currently always set to 100. So you don't need to
-# change this on 2.6.
-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
-
-if [ $DO_REMOUNT_NOATIME -eq 1 ]; then
+if [ $DO_REMOUNT_NOATIME -eq 1 ] ; then
 	NOATIME_OPT=",noatime"
 fi
 
@@ -386,11 +381,11 @@ case "$1" in
 
 		case "$KLEVEL" in
 			"2.4")
-				echo "1"				> /proc/sys/vm/laptop_mode
+				echo 1					> /proc/sys/vm/laptop_mode
 				echo "30 500 0 0 $AGE $AGE 60 20 0"	> /proc/sys/vm/bdflush
 				;;
 			"2.6")
-				echo "5"				> /proc/sys/vm/laptop_mode
+				echo 5					> /proc/sys/vm/laptop_mode
 				echo "$AGE"				> /proc/sys/vm/dirty_writeback_centisecs
 				echo "$AGE"				> /proc/sys/vm/dirty_expire_centisecs
 				echo "$DIRTY_RATIO"			> /proc/sys/vm/dirty_ratio
@@ -420,16 +415,16 @@ case "$1" in
 		U_AGE=$((100*$DEF_UPDATE))
 		B_AGE=$((100*$DEF_AGE))
 		echo -n "Stopping laptop_mode"
-		echo "0" > /proc/sys/vm/laptop_mode
-		if [ -f /proc/sys/fs/xfs/age_buffer ] && [ ! -f /proc/sys/fs/xfs/lm_age_buffer ] ; then
+		echo 0 > /proc/sys/vm/laptop_mode
+		if [ -f /proc/sys/fs/xfs/age_buffer -a ! -f /proc/sys/fs/xfs/lm_age_buffer ] ; then
 			# These need to be restored, if there are no lm_*.
-			echo "$(($XFS_HZ*$DEF_XFS_AGE_BUFFER))" 	> /proc/sys/fs/xfs/age_buffer
-			echo "$(($XFS_HZ*$DEF_XFS_SYNC_INTERVAL))" 	> /proc/sys/fs/xfs/sync_interval
+			echo $(($XFS_HZ*$DEF_XFS_AGE_BUFFER))	 	> /proc/sys/fs/xfs/age_buffer
+			echo $(($XFS_HZ*$DEF_XFS_SYNC_INTERVAL)) 	> /proc/sys/fs/xfs/sync_interval
 		elif [ -f /proc/sys/fs/xfs/age_buffer_centisecs ] ; then
 			# These need to be restored as well.
-			echo "$((100*$DEF_XFS_AGE_BUFFER))" > /proc/sys/fs/xfs/age_buffer_centisecs
-			echo "$((100*$DEF_XFS_SYNC_INTERVAL))" > /proc/sys/fs/xfs/xfssyncd_centisecs
-			echo "$((100*$DEF_XFS_BUFD_INTERVAL))" > /proc/sys/fs/xfs/xfsbufd_centisecs
+			echo $((100*$DEF_XFS_AGE_BUFFER))	> /proc/sys/fs/xfs/age_buffer_centisecs
+			echo $((100*$DEF_XFS_SYNC_INTERVAL))	> /proc/sys/fs/xfs/xfssyncd_centisecs
+			echo $((100*$DEF_XFS_BUFD_INTERVAL))	> /proc/sys/fs/xfs/xfsbufd_centisecs
 		fi
 		case "$KLEVEL" in
 			"2.4")
@@ -442,7 +437,7 @@ case "$1" in
 				echo "$DEF_DIRTY_BACKGROUND_RATIO"	> /proc/sys/vm/dirty_background_ratio
 				;;
 		esac
-		if [ $DO_REMOUNTS -eq 1 ]; then
+		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
@@ -464,13 +459,13 @@ case "$1" in
 		echo "."
 		;;
 	*)
-		echo "Usage: $0 {start|stop}"
+		echo "Usage: $0 {start|stop}" 2>&1
+		exit 1
 		;;
 
 esac
 
 exit 0
-
 --------------------CONTROL SCRIPT END--------------------------------------------