pheww… I was working on my router the last 4 hours. We had a short brownout and I had to wait for fsck. This was when I decided to what I had planned for long: changing the filesystem to reiserfs. To make it short (I want to go to bed now ) it could be done without even rebooting the system (when you have reiser in the kernel) but I needed several reboot and some twiddling on the grub commandline.
I tried to everything with pivot_root but failed when I tried to unmount the old root. But booting the old kernel (I have an extra boot partition) with the kerneloption root=/dev/hdb2 did the trick for me.
I wonder if everyone has understood a word? However - good night everybody!