[SOLVED] BTRFS filesystem corrupted. help needed

mathew2214 · July 8, 2020, 5:39pm

my home server’s main SSD runs BTRFS. there was recently a power outage and my system is no longer able to function at all because of it.
i have a debian live session on a USB device i can boot, which is how i got these logs. this is using Linux 4.19.

i can read most of the files on this SSD, but there are some that cause errors when i try to read them. it so happens that at least one of these error-causing files is very important and i would like to avoid losing it by any means necessary.

i have already been ridiculed by my peers for not having a backup ready-to-go. lesson definitely learned. a backup script will be my first priority if/when i get this system back up and running.

my sincerest apologies, but i have no way to properly get a textual copy of my dmesg, the best i can do is upload pictures i have taken with my phone.

Terminal images

Adubs · July 8, 2020, 5:46pm

I would start with ddrescue and image that drive so you can work on the image

mathew2214 · July 8, 2020, 6:20pm

i now have an image of the SSD in question. ddrescue reports zero errors. this makes me believe that there is no physical damage on the SSD.

Adubs · July 8, 2020, 6:36pm

I wouldnt expect there to be. The errors should just be limited to the data itself. Maybe now throw testdisk at the image and see what happens.

mathew2214 · July 8, 2020, 7:03pm

i cant seem to find any option within testdisk to attempt to recover the data

Adubs · July 8, 2020, 7:05pm

does it detect the filesystem correctly?

mathew2214 · July 8, 2020, 7:07pm

it correctly detects the partition table, but the FAT32 bootloader partition and the main BTRFS partition both show up as “MS DATA”. the swap partition is detected correctly.

mathew2214 · July 8, 2020, 7:09pm

pressing “P” to list files yields the message: “Support for this filesystem hasn’t been implemented”

Adubs · July 8, 2020, 7:11pm

Go ahead and set the partition you believe is your btrfs to primary and write it out. Once completed you can attempt to mount it.

Adubs · July 8, 2020, 7:12pm

It would seem this is a known shortcoming of testdisk and btrfs

https://forum.cgsecurity.org/phpBB3/viewtopic.php?t=8399

mathew2214 · July 8, 2020, 7:19pm

attempting to loop-mount the BTRFS partition from the image yields an error identical to what happens when i tried to mount it straight from the SSD.

Adubs · July 8, 2020, 7:27pm

hm, maybe use photorec to see what it yields as far as files?

I’m not much of a data recovery person beyond the simple stuff.

mathew2214 · July 8, 2020, 8:24pm

UPDATE: i have used “btrfs restore” to create a copy of every file on the corrupted filesystem. including the ones i had trouble reading.
im not certain every file was copied correctly, but i have no choice but to assume they were. these copies are on my mass storage array.

unsure what to do now, still have a corrupted BTRFS tree on the SSD.

Adubs · July 8, 2020, 8:32pm

well you have the image, so you could copy it for good measure and then begin rebuilding your setup.

mathew2214 · July 8, 2020, 8:43pm

i cant write anything to this SSD. BTRFS forces it to read only mode since it errors while mounting

Adubs · July 8, 2020, 8:48pm

interesting. got any smart data?

mathew2214 · July 8, 2020, 9:05pm

smartctl says the SSD is fine. no errors.

Adubs · July 8, 2020, 9:07pm

unmount it and nuke it then.

mathew2214 · July 8, 2020, 9:28pm

id rather not have to recreate my bootloader setup. there must be a way to repair the existing system

Adubs · July 8, 2020, 9:29pm

can you not just restore it after you’ve reformatted it?