On Sun, Feb 21, 2021 at 4:16 PM George R Goffe <grgoffe@xxxxxxxxx> wrote: >> On Sunday, February 21, 2021, 1:48:52 PM PST, Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: > That works for me. But you could alternatively try: > > mount /dev/vdb /mnt/btrfs > losetup -r /dev/loop0 /mnt/btrfs/ext2_saved/image > # losetup > NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE DIO LOG-SEC > /dev/loop0 0 0 0 1 /export/home/ext2_saved/image 0 512 > > blkid /dev/loop0 > # this command responds with nothing That happens if there's no signature or when running the command as an unprivileged user. > # the file command responds with: > # file /export/home/ext2_saved/image > #/export/home/ext2_saved/image: ERROR: cannot read `/export/home/ext2_saved/image' (Input/output error) That's not good. What do you see in dmesg at the time of this error? What about: e2fsck -fvn /dev/loop0 If this file is somehow damaged, I'm skeptical that rolling back the conversion to ext4 will succeed. But that's not the only option... A bit involved but it's possible to use device-mapper to create an overlay block device, i.e. keep this ext2_saved/image file as read-only and redirect writes to a sparse file, thereby making change reversible. And then use e2fsck -b to specify a backup super block for repair. Sooo :D this guide is designed to make it easy to setup many such overlays for RAID recovery. You could either use it as-is, or deconstruct it for just the single device you have - where your device is loop0 since it's an image file you're trying to recover. https://raid.wiki.kernel.org/index.php/Recovering_a_failed_software_RAID#Making_the_harddisks_read-only_using_an_overlay_file -- Chris Murphy _______________________________________________ test mailing list -- test@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to test-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/test@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
