casper toram forgets to disconnect loop device

[komputes]

Binary package hint: ubiquity

Ubiquity cannot install if you are booting LiveCD directly from ISO. Booting directly from GRUB to the ISO, mounts the ISO to /isodevice. Ubiquity will not install (even if on separate disk) if this is not unmounted. The result being that one cannot install Ubuntu in this method. This method can be used to create a recovery partition or a multi-usb bootable drive. For more explanation on how to do this:

========== START ==========

    * Run the following commands which will create the directory /boot/iso and download the iso file to that directory.

$ sudo -s
# mkdir /boot/iso
# cd /boot/iso
# wget http://releases.ubuntu.com/maverick/ubuntu-10.10-desktop-i386.iso

    * Add a custom menu entry in GRUB2 configuration file. Edit /etc/grub.d/40_custom as root to look like this:

#!/bin/sh
echo "Adding 40_custom." >&2
exec tail -n +3 $0

menuentry "Maverick CD Image ISO" {
set isofile=/boot/iso/ubuntu-10.10-desktop-i386.iso
loopback loop (hd0,1)$isofile
linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile noprompt noeject
initrd (loop)/casper/initrd.lz
}

    * Afterwards, run update-grub for the changes to be propagated to /boot/grub/grub.cfg

# update-grub
Generating grub.cfg ...
Found linux image: /boot/vmlinuz-...
Found initrd image: /boot/initrd.img-...

========== STOP ==========

The result of booting from the ISO directly from GRUB, is that the CD is that the partition where the ISO is located is mounted to /isodevice. Ubiquity seems to want to have control of all disks and unmount all disks before it starts installing. In the images here you see the example is sda2 for / and sda for the MBR. I have also tried this with a secondary disk where sdb1 was to be used for / and sdb for the MBR and ubiquity still complained that it had to to unmount /isodevice, even though it is on sda1. Doesn't make much sense to unmount a disk if you will not be editing any part of it.

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: ubiquity 2.4.8
ProcVersionSignature: Ubuntu 2.6.35-22.33-generic 2.6.35.4
Uname: Linux 2.6.35-22-generic i686
NonfreeKernelModules: wl
Architecture: i386
Date: Thu Dec 2 16:34:42 2010
LiveMediaBuild: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity

[Evan (ev)]

You need to preseed the following:

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

[komputes (komputes)]

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.

[komputes (komputes)]

This no longer affects me with the latest version.

[Krainov Lev (lev-krainov)]

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

[Aditya (meta1729)]

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.

[experimancer (experimancer)]

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 :(

[experimancer (experimancer)]

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.

[Launchpad Janitor (janitor)]

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

[gregrwm (gregrwm)]

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.

[Phillip Susi (psusi)]

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.

[Daniel Richard G. (skunk)]

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.)

[Phillip Susi (psusi)]

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