encryption and unmounting loopback device - help

From: swamp (swamp_at_linux.net)
Date: 06/21/04 

Date: Mon, 21 Jun 2004 13:40:39 +0100

Hello all...

I am fairly new to Linux, been using it for 6 months now so still learning
but love it. I am messing about trying to create an encrypted file which
can be mounted as required. I am having problems unmounting the loop0
device though. This is what I had done so far :-

dd if=/dev/zero bs=1G count=1 of=./myfile 1+0 records in
1+0 records out

(To create a 1G file)

----------------------------------------------

/sbin/modprobe cryptoloop && /sbin/lsmod | grep cryptoloop cryptoloop

(load modules ?)

/sbin/losetup -e blowfish /dev/loop0 ./myfile Password:

(link to loop0 and use blowfish encryption)

-----------------------------------------------

/sbin/mkfs.ext2 /dev/loop0

(format the new file)

-----------------------------------------------

mount -t ext2 /dev/loop0 /mnt/arc1

(Then drop some files to secure inside /mnt/arc1)

-----------------------------------------------

umount /mnt/arc1 -l
/sbin/losetup -d /dev/loop0
ioctl: LOOP_CLR_FD: Device or resource busy

That last bit to umount loop0 is the problem ? Why is the device busy if I
have already unmounted the folder.

David