This bug is missing log files that will aid in diagnosing the problem. >From a terminal window please run:
apport-collect 1391429 and then change the status of the bug to 'Confirmed'. If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'. This change has been made by an automated script, maintained by the Ubuntu Kernel Team. ** Changed in: linux (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1391429 Title: grub-probe takes snapshot LV instead of origin Status in “grub2” package in Ubuntu: New Status in “linux” package in Ubuntu: Incomplete Bug description: grub-probe takes the snapshot of my root LV as if it was the legitimate root device. This is an issue because in any case an update-grub / grub-mkconfig runs, my GRUB config will be rewritten so that the system would boot from the snapshot. This is really undesirable. root@thinkpad:~# mount | grep " / " /dev/mapper/thinkvg-rootlv on / type btrfs (rw,subvol=@) root@thinkpad:~# lvs LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert homelv thinkvg -wi-ao--- 64,00g rootlv thinkvg owi-aos-- 16,00g snap-rootlv thinkvg sri-a-s-- 16,00g rootlv 2,54 swap0 thinkvg -wi-ao--- 2,00g swap1 thinkvg -wi-ao--- 2,00g root@thinkpad:~# grub-probe --target=device / /dev/mapper/thinkvg-snap--rootlv The most apparent reason could be that obviously the UUIDs of the origin and the snapshot are the same. root@thinkpad:~# blkid /dev/thinkvg/*rootlv /dev/thinkvg/rootlv: LABEL="SystemRoot" UUID="dd6904ff-d187-43a8-ae18-478283f29d68" UUID_SUB="80b3d748-51e0-4a51-a021-55005b0ec434" TYPE="btrfs" /dev/thinkvg/snap-rootlv: LABEL="SystemRoot" UUID="dd6904ff-d187-43a8-ae18-478283f29d68" UUID_SUB="80b3d748-51e0-4a51-a021-55005b0ec434" TYPE="btrfs" However, strangely, if I hide the snapshot by deleting nodes (as I can't deactivate a snapshot without deactivating its origin too – lost nodes will come back after reboot, or sometimes can be recovered with "vgscan --mknodes"), grub-probe won't find any device: root@thinkpad:~# rm /dev/thinkvg/snap-rootlv /dev/mapper/thinkvg-snap--rootlv /dev/dm-5 root@thinkpad:~# grub-probe --target=device / grub-probe: error: cannot find a device for / (is /dev mounted?). I'd expect grub-probe to find /dev/mapper/thinkvg-rootlv, and ignore the snapshot. For me, it serves as an evidence that grub-probe totally ignores LVM, or at least makes no attempt to differentiate snapshots from origins, while LV snapshots are easily recognized from their "s" flag. The same thing happened when I manually cloned the root LV as "backup- rootlv", though since it was created with simply dd-ing "rootlv" over, the LVs were not related on LVM level, thus grub-probe legitimately treated it as a stand-alone device that has the same file system as the one being mounted. Still, it would be best is grub-probe found the device that is actually mounted, no matter what clones of the device exist. But at least it should certainly ignore LVM snapshots. I experienced this bug on 2 systems: on Trusty Tahr and on Utopic Unicorn. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1391429/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp