mount_overlay_squash

#!/bin/sh

## hyphop ## 

. ./,config


grep squashfs /proc/filesystems 1>/dev/null || modprobe squashfs
grep squashfs /proc/filesystems 1>/dev/null || { 
    echo "[e] not have squashfs"
    exit 1
}

ovlmod=""

for v in overlayfs overlay aufs; do

    [ -d /sys/module/$v ] || { 
    modprobe $v 2>/dev/null
    }
    [ -d /sys/module/$v ] && {
	ovlmod=$v
	break
    }

done

#override mode
#ovlmod=aufs

echo "[i] used $ovlmod" >&2 

p=$PWD
p=.

[ -d $src ] || mkdir $src

#sfs=$src.squashfs
sfs=$squash_src

ro_level=$p/$src.ro
rw_level=$p/$src.rw

[ -d $ro_level ] || mkdir $ro_level
[ -d $rw_level ] || mkdir $rw_level

work_dir=$p/$src

mount -o ro $sfs $ro_level

case $ovlmod in  
    overlay)
    mount -t overlay overlay -o lowerdir=$ro_level,upperdir=$rw_level,workdir=$work_dir \
	$work_dir
    break
    ;;
    overlayfs)
    mount -t overlayfs -o lowerdir=$ro_level,upperdir=$rw_level \
	none $work_dir
    break
    ;;
    aufs)
    mount -t aufs -o br:$rw_level:$ro_level \
	none $work_dir
    break
    ;;
esac

grep $work_dir /proc/mounts | grep $ovlmod 1>/dev/null || {
    echo "[e] working dir "$work_dir" not mounted as overlay"
    exit 1
}

echo "[i] working dir $work_dir mounted as overlay  RO: $ro_level RW: $rw_level"

## OK