From 6146d1904aad28f0bacbb6986205c28bb7020356 Mon Sep 17 00:00:00 2001
From: Michael Tremer <michael.tremer@ipfire.org>
Date: Thu, 3 Dec 2015 16:03:29 +0000
Subject: [PATCH] ramdisk: Avoid copying data if no ramdisk is used

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---
 src/initscripts/init.d/collectd  | 24 ++++------------
 src/initscripts/init.d/functions | 48 +++++++++++++++++++++-----------
 src/initscripts/init.d/vnstat    | 25 ++++-------------
 3 files changed, 43 insertions(+), 54 deletions(-)

diff --git a/src/initscripts/init.d/collectd b/src/initscripts/init.d/collectd
index 24187d215..e5c35950d 100644
--- a/src/initscripts/init.d/collectd
+++ b/src/initscripts/init.d/collectd
@@ -13,20 +13,9 @@ fi
 case "$1" in
 	start)
 		if use_ramdisk; then
-			#mount ramdisk
-			if ! mountpoint $RRDLOG &>/dev/null; then
-				boot_mesg "Mount rrd Ramdisk..."
-				if [ $(find "$RRDLOG" | wc -l) -ne 1 ]; then
-					backup_ramdisk "$RRDLOG"
-				fi
-				mount_ramdisk "$RRDLOG"
-				evaluate_retval
-
-				#restore old values to ramdisk if exist
-				restore_ramdisk "$RRDLOG"
-			fi
-		else
-			restore_ramdisk "$RRDLOG"
+			boot_mesg "Mounting RRD ramdisk..."
+			mount_ramdisk "${RRDLOG}"
+			evaluate_retval
 		fi
 
 		# If run from init and collectd alrady started then exit silent
@@ -122,10 +111,9 @@ case "$1" in
 		boot_mesg "Stopping Collection daemon..."
 		killproc /usr/sbin/collectd
 		evaluate_retval
-		backup_ramdisk "$RRDLOG"
-		umount_ramdisk "$RRDLOG"
-		# sync after backup...
-		sync
+
+		# Umount the ramdisk (if any)
+		umount_ramdisk "${RRDLOG}"
 		;;
 	restart)
 		${0} stop
diff --git a/src/initscripts/init.d/functions b/src/initscripts/init.d/functions
index bd2c946e0..fc4d8a4b9 100644
--- a/src/initscripts/init.d/functions
+++ b/src/initscripts/init.d/functions
@@ -743,29 +743,45 @@ use_ramdisk() {
 }
 
 mount_ramdisk() {
-	mount -t tmpfs none $1
-}
+	local path="${1}"
+	local path_tmpfs="${path}.tmpfs"
 
-umount_ramdisk() {
-	if mountpoint $1 &>/dev/null; then
-		umount $1
+	# Check if the ramdisk is already mounted
+	if mountpoint "${path}" &>/dev/null; then
+		return 0
 	fi
-}
 
-backup_ramdisk() {
-	if [ ! -e $1.bak ]; then
-		mkdir -p $1.bak
-	fi
+	# Create ramdisk
+	mkdir -p "${path_tmpfs}"
+	mount -t tmpfs none "${path_tmpfs}"
+
+	# Restore ramdisk content
+	cp -pR "${path}/*" "${path_tmpfs}"
 
-	cp -pR $1/* $1.bak/
-	rm -rf $1/*
+	# Move ramdisk to final destination
+	mount --move "${path_tmpfs}" "${path}"
+	rm -f "${path_tmpfs}"
 }
 
-restore_ramdisk() {
-	if [ -e $1.bak ];then
-		cp -pR $1.bak/* $1/
-		rm -rf $1.bak/*
+umount_ramdisk() {
+	local path="${1}"
+	local path_tmpfs="${path}.tmpfs"
+
+	# Check if a ramdisk is actually mounted
+	if ! mountpoint "${path}" &>/dev/null; then
+		return 0
 	fi
+
+	# Move the ramdisk
+	mkdir -p "${path_tmpfs}"
+	mount --move "${path}" "${path_tmpfs}"
+
+	# Backup ramdisk content
+	cp -pR "${path_tmpfs}/*" "${path}"
+
+	# Destroy the ramdisk
+	umount "${path_tmpfs}"
+	rm -f "${path_tmpfs}"
 }
 
 # End $rc_base/init.d/functions
diff --git a/src/initscripts/init.d/vnstat b/src/initscripts/init.d/vnstat
index 2593afe4d..05c35eefc 100755
--- a/src/initscripts/init.d/vnstat
+++ b/src/initscripts/init.d/vnstat
@@ -13,31 +13,16 @@ fi
 case "$1" in
 	start)
 		if use_ramdisk; then
-			if ! mountpoint $VNSTATLOG &>/dev/null; then
-				boot_mesg "Mount vnstat ramdisk..."
-				if [ $(find "$VNSTATLOG" | wc -l) -ne 1 ]; then
-					backup_ramdisk "$VNSTATLOG"
-				fi
-				mount_ramdisk "$VNSTATLOG"
-				evaluate_retval
-				$0 restore
-			fi
-		else
-			restore_ramdisk "$VNSTATLOG"
+			boot_mesg "Mounting vnstat ramdisk..."
+			mount_ramdisk "${VNSTATLOG}"
+			evaluate_retval
 		fi
 		;;
 	stop)
-		$0 backup
-		umount_ramdisk "$VNSTATLOG"
-		;;
-	backup)
-		backup_ramdisk "$VNSTATLOG"
-		;;
-	restore)
-		restore_ramdisk "$VNSTATLOG"
+		umount_ramdisk "${VNSTATLOG}"
 		;;
 	*)
-		echo "Usage: $0 {start|stop|backup}"
+		echo "Usage: $0 {start|stop}"
 		exit 1
 		;;
 esac
-- 
2.39.2