#!/bin/sh
# defrag v0.04 by Con Kolivas <kernel@kolivas.org
# Braindead fs-agnostic defrag to rewrite files in order largest to smallest
# Run this in the directory you want all the files and subdirectories to be
# reordered. It will only affect one partition.

trap 'abort' 1 2 15

renice 19 $$ > /dev/null

abort()
{
	echo -e "\nAborting"
	rm -f tmpfile dirlist
	exit 1
}

fail()
{
	echo -e "\nFailed"
	abort
}

declare -i filesize=0
declare -i numfiles=0

#The maximum size of a file we can easily cache in ram
declare -i maxsize=`awk '/MemTotal/ {print $2}' /proc/meminfo`
(( maxsize-= `awk '/Mapped/ {print $2}' /proc/meminfo` ))
(( maxsize/= 2))

if [[ -a tmpfile || -a dirlist  ]] ; then
	echo dirlist or tmpfile exists
	exit 1
fi

# Sort in the following order:
# 1) Depth of directory
# 2) Directory name
# 3) Size descending
# 4) FileName

echo "Creating list of files to defrag..."

find -xdev -type f -printf "%d\t%h\t%s\t%p\n" | \
sort -t \t -k 1,1n -k 2,2 -k 3,3nr -k 4 | \
awk -F "\t" '{print $4}' > dirlist

if (( $? )) ; then
	fail
fi

numfiles=`wc -l dirlist | awk '{print $1}'`

echo -e "$numfiles files to defrag \n"

cat dirlist | while read i;
do
	(( --numfiles ))
	if [[ ! -f $i ]]; then
		continue
	fi

	filesize=`find "$i" -printf "%s"`
	# read the file first to cache it in ram if possible
	if (( filesize < maxsize ))
	then
		echo -e "\r Files left to defrag: $numfiles                    \c"
		cat "$i" > /dev/null
	else
		echo -e "\r Defragging large file sized $filesize ...          \c"
	fi
	datestamp=`find "$i" -printf "%s"`
	cp -a -f "$i" tmpfile
	if (( $? )) ; then
		fail
	fi
	# check the file hasn't been altered since we copied it
	if [[ `find "$i" -printf "%s"` != $datestamp ]] ; then
		continue
	fi

	mv -f tmpfile "$i"
	if (( $? )) ; then
		fail
	fi
done

echo -e "\n"

rm -f dirlist