Mounting self-made cloop file - how?

[DirkS]

I'm at it.

The method I tried (twice) on Knoppix 7.0 was, after becoming root:

# mkdir /media/test-cloop
# mount /media/sdc2/sda1_2017-03-04.cloop /media/test-cloop -o loop=/dev/cloop3,ro

I didn't even need to specify the filesystem type.

This method also works in 7.3 but fails in 7.4.2, 7.7.0 and 7.7.1
For the following tests I used /media/sr0 as mountpoint instead of creating a directory named /media/test-cloop.
Using the commands that are contained in the cloop file at the beginning, slightly modified:

#modprobe cloop file=/media/sdd2/sda1_2017-03-01.cloop; echo $?
# mount -r -t auto /dev/cloop3 /media/sr0

This works in 7.4.2, even though it took me several tries to find the correct number after /dev/cloop. But this method does not work in 7.7.0 and 7.7.1:

root@Microknoppix:/media/sdd2# mount -r -t auto /dev/cloop3 /media/sr0
mount: /dev/cloop3: Superblock konnte nicht gelesen werden (Translation: Superblock could not get read)

Also failed with all other cloop devices.

Your method:

root@Microknoppix:/media/sdd2# losetup --verbose --read-only /dev/cloop6 /media/sdd2/sda1_2017-03-04.cloop
root@Microknoppix:/media/sdd2# mount --verbose  /dev/cloop6 /media/sr0

works in 7.7.0. Yay! I have to reboot to test it in 7.7.1 and/or older versions, but I wanted to write this post with the results so far first.

By the way, while still being root I was able to do

root@Microknoppix:/media/sde2# df | grep sr0; echo $?
/dev/cloop6        307196     233384      73812   76% /media/sr0
0
root@Microknoppix:/media/sdd2# umount /dev/sr0
root@Microknoppix:/media/sdd2#  df | grep sr0; echo $?
1

so umounting as root works for me. But I cannot free/detach /dec/cloop6:

root@Microknoppix:/media/sdd2#  losetup --verbose -d /dev/cloop6
losetup: /dev/cloop6: Benutzung des Gerätes ist fehlgeschlagen: Erfolg (Translation: Using the device failed: Success - sorry, that's what it says.)

So indeed, at this point a reboot is required.

[DirkS]

Wrapping up.

root@Microknoppix:/media/sdd2# losetup --verbose --read-only /dev/cloop6 /media/sdd2/sda1_2017-03-04.cloop
root@Microknoppix:/media/sdd2# mount --verbose  /dev/cloop6 /media/sr0

also works in 7.7.1. Double Yay! So I have a solution for the newest Knoppix. Now I hope that it will still work in the upcoming Knoppix 8.

Is there a way to declare the thread as "solved"?

[utu]

Is there a way to declare the thread as "solved"?

I suggest you PM Werner P. Schulz to see if this is possible.

[DirkS]

Thanks, utu, I haven't done this yet, but I'm considering it.

Meanwhile I'm going through the mailing list and found something:

https://lists.debian.org/debian-knop.../msg00000.html - title: "losetup from 7.6.1 can't detach a cloop device" - sounds familiar, isn't it? Seems like this is caused by a change in losetup. Klaus Knopper posted an answer in which he mentioned that he filed a bug report and using the losetup of busybox should work. I can't test that right now, just leaving the info here so it will not get forgotten.