casper toram forgets to disconnect loop device

You need to preseed the following:

d-i partman/filter_mounted boolean false
d-i ubiquity/partman-skip-unmount boolean true

How can one preseed d-i values on a LiveCD with ubiquity? Can you please provide instructions and I will test and get back to you.

This no longer affects me with the latest version.

reproduced in kubuntu-11.10-desktop-amd64.iso , workaround with exit 0 in /lib/partman/commit.d/01unmount_busy solved the problem

Present in xubuntu-14.04-desktop-i386.iso. The installer says it needs to unmount /isodevice even if NO partition changes (create/delete/resize) are requested. All that is requested is formatting of other partition as ext4.

Please reopen this bug.

Still present in ubuntu-14.04-desktop iso, booted from grub2.

No way to continue with installation cause "/isodevice cannot be unmounted" (the operation of which is not even needed).

Not "invalid" or "fixed" not even in any of this bugs duplicates.

Wonder why this has ever been closed, even if it has been around for atleast 4 years in each and every Ubunut installatiion .iso image.?

The quality of Ubuntu distributions is getting worse and worse every year.. And seems that rven this severe installation bugs are not fixed :(

Fix is actully here: https://help.ubuntu.com/community/Grub2/ISOBoot (i.e add "toram" to relevant Grub2 menuentry or manually umount the /isodevice with "sudo umount -lrf /isodevice" and re-start the installation.

Status changed to 'Confirmed' because the bug affects multiple users.

confirmed that the 'umount -lrf /isodevice' workaround works on the bionic iso of 2018/2/8. i didn't even use 'toram'.

everyone expects they need either burn a cd, use a thumb or external drive, or use another installer, eg mini.iso. with this workaround, or better yet if this bug gets fixed, none of those are necessary.

Looks like after casper copies the squashfs to ram, it forgets to disconnect the loop device. The workaround is to run losetup -d /dev/loop0 and umount /isodevice.

Philip Susi: Confirmed with the Bionic live CD:

root@xubuntu:~# cat /proc/cmdline
BOOT_IMAGE=(loop)/casper/vmlinuz boot=casper iso-scan/filename=/linux/xubuntu-18.04-desktop-amd64.iso toram

root@xubuntu:~# umount /isodevice
umount: /isodevice: target is busy.

root@xubuntu:~# losetup -d /dev/loop0

root@xubuntu:~# umount /isodevice
(succeeds)

However, I did not observe the issue as originally reported; Ubiquity was able to install the system even with /isodevice mounted and unable to be unmounted. (In my case, the ISO file was on a USB thumbdrive, and I installed to a hard drive.)

Yes; the install only fails if the iso file is on your hard disk.

Here's a patch for casper to delete the loopback after copying:

diff --git a/scripts/casper b/scripts/casper
index 5861ced..fa06c0d 100644
--- a/scripts/casper
+++ b/scripts/casper
@@ -191,7 +191,7 @@ copy_live_to() {
     if [ -e ${copyfrom}/.disk ]; then
         cp -a ${copyfrom}/.disk ${copyto}
     fi
- umount ${copyfrom}
+ umount -d ${copyfrom}
     mount -r -o move ${copyto} ${copyfrom}
     rmdir ${copyto}
     return 0

Regarding comment #20, 2019-10-03,

I tried this patch and umount -d ${copyfrom} seems like it should unmount the loopback device, but it does not.

Yet this works:

root@xubuntu:~# losetup -d /dev/loop0
root@xubuntu:~# umount /isodevice

I am still looking that this, but was curious if anybody else is experiencing the same issue when booting a recent live iso from disk.

I tried explicitly using losetup -d /dev/loop0 right before umount ${copyfrom} in the casper script and it did not work. losetup -d /dev/loop0 and umount /isodevice does work out of rc.local just fyi.

Did you try to force umount at line

https://git.launchpad.net/ubuntu/+source/casper/tree/scripts/casper?h=ubuntu/focal-devel#n200

Even better option of umount : -d ( detach loop devices )

So sudo umount -lfd /isodevice

should be the way.

Any update on this small but big win fix ?

Still on 20.04.1 ...

Just an Update : umount -lfd was not enough

So I'm trying to embed a startup script in a Live custom ISO :

losetup -d /dev/loop0
umount -lfd /isodevice

And it works

When booting Kubuntu 20.04.1 (LTS) iso the workaround of detaching /dev/loop0 device and then unmounting /isodevice was required, as in comment #27. Then setup finished.

Issue is still occurring on ubuntu-20.04.3-live-server-amd64.

Unfortunately having difficulty unmounting the iso file with the following two commands,

losetup -d /dev/loop0
umount /isodevice

UPDATE: Specific issue related to the Dell Optiplex 5080 unit I was using
https://askubuntu.com/questions/1377159/ubuntu-server-20-04-3-setup-stuck-at-block-probing-did-not-discover-any-disks/1377260#1377260

This issue got worse because casper-lupin functionality was incompletely ported into casper itself.

I wrote a patch that ubuntu developers will need to add in order to get back at the point that this issue describes. The patch is here:
https://bugs.launchpad.net/ubuntu/+source/lupin/+bug/1960457/comments/34

Disconnecting the loop device may not always be desired after using "toram": See https://bugs.launchpad.net/ubuntu/+source/lupin/+bug/1960457/comments/33

Thus, it may be advisable to ask for that explicitly. I propose using "detach". So the system should be booted with "toram detach".

Solving this problem requires less than 10 lines. I hope that developers can add the patch below.

For this patch to work it is necessary to fix the issue mentioned previously beforehand: https://bugs.launchpad.net/ubuntu/+source/lupin/+bug/1960457/comments/34 first (4 lines)

Here is the patch:

--- scripts/casper_1477
+++ scripts/casper
@@ -75,6 +75,8 @@
                 export TORAM="Yes" ;;
             todisk=*)
                 export TODISK="${x#todisk=}" ;;
+ detach)
+ export DETACH="Yes" ;;
             hostname=*)
                 export CMD_HOST="${x#hostname=}" ;;
             userfullname=*)
@@ -1042,6 +1044,13 @@
     run_scripts /scripts/casper-bottom
     [ "$quiet" != "y" ] && log_end_msg

+ if [ "${live_dest}" ] && [ -z "$PERSISTENT" ] && [ "$DETACH" ]; then
+ if grep -q '^[^ ]* /root/isodevice ' /proc/mounts; then
+ losetup -d /dev/loop0
+ umount /root/isodevice
+ fi
+ fi
+
     # Close the fd's associated with debconf-communicate.
     exec 3>&- 4<&-
     rm -f /tmp/debconf-in.fifo

There are other options for implementing this, for example:
a) detaching as the default behavior and allowing for a "nodetach" argument in cmdline
b) removing "/root" from the patch (in the 2 lines where it appears), will make this work without fixing https://bugs.launchpad.net/ubuntu/+source/lupin/+bug/1960457/comments/34 first.

> Disconnecting the loop device may not always be desired after using "toram": See https://bugs.launchpad.net/ubuntu/+source/lupin/+bug/1960457/comments/33

That comment was very likely not in the context of "toram" usage. That users requirements appear to be iso loopback loading access to /isodevice from the overlay root.

I prefer a nodetach option as I think the expected use case (or maybe just mine) for toram is to remove the usb device on which resides the loopback loaded iso so that the device can be used elsewhere while the live cd is running.