https://bugzilla.suse.com/show_bug.cgi?id=1149980 https://bugzilla.suse.com/show_bug.cgi?id=1149980#c2 --- Comment #2 from Stefan Hundhammer --- From that y2log it appears that it's the Btrfs subvolumes that cause all those confusing errors in the log. All entries in /proc/mounts (reformatted and minus the mount option to avoid Bugzilla mangling it completely): tmpfs / tmpfs tmpfs / tmpfs proc /proc proc sysfs /sys sysfs /dev/loop0 /parts/mp_0000 squashfs /dev/loop1 /parts/mp_0001 squashfs devtmpfs /dev devtmpfs devpts /dev/pts devpts rpc_pipefs /var/lib/nfs/rpc_pipefs rpc_pipefs /dev/loop2 /mounts/mp_0000 squashfs /dev/loop3 /mounts/mp_0001 squashfs /dev/loop5 /mounts/mp_0003 squashfs /dev/loop6 /mounts/mp_0004 squashfs /dev/sda2 /mnt btrfs /dev/sda2 /mnt/.snapshots btrfs /dev/sda2 /mnt/boot/grub2/i386-pc btrfs /dev/sda2 /mnt/boot/grub2/x86_64-efi btrfs /dev/sda2 /mnt/home btrfs /dev/sda2 /mnt/opt btrfs /dev/sda2 /mnt/root btrfs /dev/sda2 /mnt/srv btrfs /dev/sda2 /mnt/tmp btrfs /dev/sda2 /mnt/usr/local btrfs /dev/sda2 /mnt/var btrfs devtmpfs /mnt/dev devtmpfs proc /mnt/proc proc sysfs /mnt/sys sysfs tmpfs /mnt/run tmpfs But we only need mounts to /mnt, so let's grep for that: /dev/sda2 /mnt btrfs /dev/sda2 /mnt/.snapshots btrfs /dev/sda2 /mnt/boot/grub2/i386-pc btrfs /dev/sda2 /mnt/boot/grub2/x86_64-efi btrfs /dev/sda2 /mnt/home btrfs /dev/sda2 /mnt/opt btrfs /dev/sda2 /mnt/root btrfs /dev/sda2 /mnt/srv btrfs /dev/sda2 /mnt/tmp btrfs /dev/sda2 /mnt/usr/local btrfs /dev/sda2 /mnt/var btrfs devtmpfs /mnt/dev devtmpfs proc /mnt/proc proc sysfs /mnt/sys sysfs tmpfs /mnt/run tmpfs Notice that all the snapshots on the root filesystem are also there. But unmounting them separately is what fails with that "filesystem busy" error, so that's what we need to avoid. -- You are receiving this mail because: You are on the CC list for the bug.

https://bugzilla.suse.com/show_bug.cgi?id=1149980 https://bugzilla.suse.com/show_bug.cgi?id=1149980#c4 --- Comment #4 from Stefan Hundhammer --- Deciding which of the entries in /proc/mounts is a true toplevel Btrfs and which is only a subvolume is very hard; even more so if it is possible that there are SEVERAL toplevel Btrfs mounts. One approach might be to check each entry during unmounting avain if it's even mounted: A previous unmount might have taken care of it as well. Of course that works only if we strictly follow the order of /proc/mounts. But that is in contradiction of the other requirement: Unmount from deeper nesting upwards to the target's root because otherwise the root will still be busy. The same applies to mounts like /boot that might have more mounts inside them. / ������/boot ��� ������/boot/efi ��� ������/boot/morestuff So we NEED to start unmounting from the deepest mounts upwards. For Btrfs (i.e. all mounts containing mount options "subvolid" or "subvol=") it is tempting to make an exception and start from the top. That works well as long as it's only subvolumes of that same Btrfs mounted inside it. But it is entirely possible that another Btrfs is mounted to that Btrfs, and that might also have those mount options "subvolid" or "subvol=". In that case, it would not be unmounted first, and unmounting the toplevel Btrfs would fail with "filesystem busy". -- You are receiving this mail because: You are on the CC list for the bug.

https://bugzilla.suse.com/show_bug.cgi?id=1149980 https://bugzilla.suse.com/show_bug.cgi?id=1149980#c6 --- Comment #6 from Stefan Hundhammer --- It turns out that you can unmount btrfs subvolumes just fine; but at least one of them, /mnt/var, tends to be busy because libzypp uses /mnt/var/cache/zypp/packages/... for its package cache. If unmounting that one fails with a "busy" error, unmounting its parent Btrfs main volume at /mnt also fails with the same error. -- You are receiving this mail because: You are on the CC list for the bug.

https://bugzilla.suse.com/show_bug.cgi?id=1149980 https://bugzilla.suse.com/show_bug.cgi?id=1149980#c8 --- Comment #8 from Stefan Hundhammer --- Related: New bug #1189793 "libzypp cache keeps /mnt/var mount busy" that I wrote when I tested my when I tested my changes. -- You are receiving this mail because: You are on the CC list for the bug.

https://bugzilla.suse.com/show_bug.cgi?id=1149980 https://bugzilla.suse.com/show_bug.cgi?id=1149980#c14 --- Comment #14 from Steffen Winterfeldt --- Thanks; the log looks much better now and it even gives useful hints. -- You are receiving this mail because: You are on the CC list for the bug.

https://bugzilla.suse.com/show_bug.cgi?id=1149980 https://bugzilla.suse.com/show_bug.cgi?id=1149980#c16 --- Comment #16 from Stefan Hundhammer --- The emergency umount code: https://github.com/yast/yast-installation/blob/master/startup/First-Stage/F1... see also bug #1189793 comment #7 for why we shouldn't rely on that and get this fixed before it escalates to that last ditch defense script. -- You are receiving this mail because: You are on the CC list for the bug.

https://bugzilla.suse.com/show_bug.cgi?id=1149980 https://bugzilla.suse.com/show_bug.cgi?id=1149980#c18 --- Comment #18 from Stefan Hundhammer --- SR to OBS: https://build.opensuse.org/request/show/914406 SR to IBS: https://build.suse.de/request/show/248874 -- You are receiving this mail because: You are on the CC list for the bug.