Public bug reported: Hi!
I identified a problem for creating persistent live usb sticks when using a second partition for 'casper-rw'. Environment: On the usb stick I created two partitions: - The first partition (/dev/sda1) is vfat which is used for the live-filesystem (filesystem.squashfs). - The second partition (/dev/sda2) is ext4 and labeled 'casper-rw' which is used for persistence. cat /proc/cmdline BOOT_IMAGE=(hd0,msdos1)/casper/vmlinuz file=/preseed/lubuntu.seed boot=casper quiet splash persistent ignore_uuid --- Error in initramfs (casper.log) while boot: mount: mounting /cow on /root failed: Invalid argument overlay mount failed Tested versions (Lubuntu): Lubuntu 18.04 (LTS) - Package casper/now 1.394 amd64 Lubuntu 19.10 - Pacakge casper/eoan 1.427 amd64 Bug: I found a bug in find_cow_device() function of casper-helpers script from initram that is responsible for this. When the setup_unionfs() function of the casper script invokes the find_cow_device() function, the live filesystem partition that was mounted in the mountroot() function is unmounted every time the function tries to search for a persistent file, making it impossible to boot. When a casper-rw file exists and is used, the problem just doesn't happen because the partition is mounted and busy, so you can't unmount it. To correct the problem, I have included a check to not unmount the partition if it is the live-filesystem partition. In that case, just return it to read-only. My fix for casper-helpers script in Lubuntu 19.10 'casper/eoan 1.427 amd64' package: /usr/share/initramfs-tools/scripts# diff -u casper-helpers casper-helpers.fix --- casper-helpers 2019-10-14 12:29:05.000000000 -0300 +++ casper-helpers.fix 2019-10-24 17:09:42.635313048 -0300 @@ -247,8 +247,10 @@ if [ -e "${cow_backing}/${pers_fpath}" ]; then echo $(setup_loop "${cow_backing}/${pers_fpath}" "loop" "/sys/block/loop*") return 0 - else + elif [ ${cow_backing} != ${livefs_root} ]; then umount ${cow_backing} + else + try_mount "${devname}" "${cow_backing}" "ro" fi fi done ---CUT HERE--- My fix for casper-helpers script in Lubuntu 18.04 (LTS) 'casper/now 1.394 amd64' package: /usr/share/initramfs-tools/scripts# diff -u casper-helpers casper-helpers.fix --- casper-helpers 2019-10-24 11:29:58.735085568 -0300 +++ casper-helpers.fix 2019-10-24 16:53:19.375302075 -0300 @@ -223,8 +223,10 @@ if [ -e "${cow_backing_mp}/${pers_fpath}" ]; then echo $(setup_loop "${cow_backing_mp}/${pers_fpath}" "loop" "/sys/block/loop*") return 0 - else + elif [ ${cow_backing_mp} != ${livefs_root} ]; then umount ${cow_backing_mp} + else + try_mount "${devname}" "${cow_backing}" "ro" fi fi done ---CUT HERE--- ** Affects: casper (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1849730 Title: [live-usb-persistent] second partition as casper-rw issue To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/casper/+bug/1849730/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs