#! /bin/sh
# blktrace    Mount debugfs on boot
# Copyright (c) 2008 by Bas Zoetekouw.
# Redistribution and use in source and binary forms, with or without
# modification, are permitted onder terms of the GPL, version 2.

### BEGIN INIT INFO
# Provides:          mountdebugfs
# Required-Start:    $local_fs mountkernfs
# Required-Stop:     $local_fs
# Should-Start:
# Should-Stop:
# Default-Start:     S 1 2 3 4 5
# Default-Stop:      0 6
# Short-Description: Mount debugfs on /sys/kernel/debug
### END INIT INFO

# load LSB functions (log_success_msg etc)
. /lib/lsb/init-functions

# main mount point
mount_dir=/sys/kernel/debug

# check if /proc/mounts exists
if ! [ -r /proc/mounts ]
then
	log_failure_msg "Failed! Couldn't read /proc/mounts."
	exit 1
fi

# no need to do anything if blktrace isn't installed
if ! [ -x /usr/sbin/blktrace ]
then
	exit 0
fi

# find where (if anywhere) debugfs is mounted
mountpoints=$( 
	awk '$3 == "debugfs" { print $2 }' < /proc/mounts
)

mount_debugfs ()
{
	# check if any of the current mountpoints is /sys/kernel/debug
	found_syskerneldebug=0
	for d in $mountpoints
	do
		if [ $d = $mount_dir ]
		then
			found_syskerneldebug=1
		fi
	done
	if [ $found_syskerneldebug -eq 1 ]
	then
		log_success_msg "Debugfs is already mounted on $mount_dir; nothing to do";
		exit 0
	fi

	# check that debugfs is supported by the kernel
	if ! [ $(  awk -F\\t '$2 == "debugfs" { print $2 }' < /proc/filesystems ) ]
	then
		log_failure_msg "Can't mount debugfs: not supported by your kernel"
		exit 0
	fi

	# check that /sys/kernel exists
	the_dir=$( dirname $mount_dir )
	if ! [ -d $the_dir ]
	then
		log_failure_msg "Can't mount debugfs on $mountdir: $the_dir doesn't exist."
		exit 1
	fi

	# do the actual mounting
	if mount -t debugfs debugfs $mount_dir
	then
		log_success_msg "Mounted debugfs on $mount_dir"
	else
		log_failure_msg "Couldn't mount debugfs on $mount_dir"
		exit 1
	fi

}

umount_debugfs ()
{
	if  [ $mountpoints ]
	then
		for d in $mountpoints
		do
			if [ $d = $mount_dir ]
			then
				if umount $d
				then
					log_success_msg "Unmounted debugfs from $d"
				else 
					log_failure_msg "Couln't unmount debugfs from $d"
				fi
			fi
		done
	else
		log_success_msg "Debugfs is not mounted; nothing to do."
	fi
}

show_status ()
{
	if  [ $mountpoints ]
	then
		for d in $mountpoints
		do
			log_success_msg "Debugfs is mounted on $d"
		done
	else
		log_success_msg "Debugfs is not mounted"
	fi
}


case "$1" in
	start)
		mount_debugfs
		;;
	stop)
		umount_debugfs
		;;
	restart|reload|force-reload)
		umount_debugfs
		exec $0 start
		;;
	status)
		show_status
		;;
	*)
		echo "Usage: $0 {start|stop|restart|reload|force-reload|status}"
		exit 1
		;;
esac

exit 0