Restored Btrfs partition not mountable

[arnogon]

I backuped my memory card which contained 1 non-boot Btrfs partition with clonezilla-live-20230426-lunar-amd64, and later restored it to the same card. After the restoration the partition is unmountable. I did all the checks before and after backup and restoration and didn't notice any error (device turned off afterwards as usual).

user@debian:~$ sudo mount /dev/mmcblk0p1 /media/user/mmcblk0p1
mount: /media/user/mmcblk0p1: can't read superblock on /dev/mmcblk0p1.
       dmesg(1) may have more information after failed mount system call.

[Steven Shiau]

The version you used was is old. Please give the latest stable one a try. E.g., 3.1.1-27 or 20231102-mantic:
https://clonezilla.org/downloads.php

Steven

[arnogon]

My memory card has already been overwritten by the restored image, so I can't backup again. I did try to restore with 20231218-noble and the same problem persisted.

[Steven Shiau]

Btrfs changes very quickly, so....
Partclone 0.3.27 supports Btrfs 6.5 IIRC. Next time when you save an image, do remember to use the latest Clonezilla live, even testing Clonezilla live.

Steven

[arnogon]

The source Btrfs partition was created last year so it couldn't be that new... Anyway, I'm more concerned about recovering the data. Is there anyway to fix the errors and get my data back?

[Steven Shiau]

Not sure. However, maybe you can try to use the Clonezilla live version you saved the image to restore it.
You should be able to find the version info in the plain text file "Clonezilla-img" in your image.

Steven

[arnogon]

Yes, that would be 20230426-lunar. I used both that and 20231218-noble to try to restore my backup, but had the same problem (unmountable partition).

[Steven Shiau]

In that case, have you tried btrfsck?

Steven

[arnogon]

I got a bunch of errors with btrfsck.

ref mismatch on [590504206336 131072] extent item 1, found 0
data extent[590504206336, 131072] bytenr mimsmatch, extent item bytenr 590504206336 file item bytenr 0
data extent[590504206336, 131072] referencer count mismatch (root 256 owner 1193734 offset 134012928) wanted 1 have 0
backpointer mismatch on [590504206336 131072]
owner ref check failed [590504206336 131072]
ref mismatch on [590504337408 126976] extent item 1, found 0
data extent[590504337408, 126976] bytenr mimsmatch, extent item bytenr 590504337408 file item bytenr 0
data extent[590504337408, 126976] referencer count mismatch (root 256 owner 1193734 offset 140697600) wanted 1 have 0
backpointer mismatch on [590504337408 126976]
owner ref check failed [590504337408 126976]
ref mismatch on [590504464384 126976] extent item 1, found 0
data extent[590504464384, 126976] bytenr mimsmatch, extent item bytenr 590504464384 file item bytenr 0
data extent[590504464384, 126976] referencer count mismatch (root 256 owner 1193734 offset 140828672) wanted 1 have 0
backpointer mismatch on [590504464384 126976]
owner ref check failed [590504464384 126976]
ref mismatch on [590504591360 135168] extent item 1, found 0
data extent[590504591360, 135168] bytenr mimsmatch, extent item bytenr 590504591360 file item bytenr 0
data extent[590504591360, 135168] referencer count mismatch (root 256 owner 1193734 offset 142213120) wanted 1 have 0
backpointer mismatch on [590504591360 135168]
owner ref check failed [590504591360 135168]
ERROR: errors found in extent allocation tree or chunk allocation
[3/7] checking free space tree
[4/7] checking fs roots
parent transid verify failed on 192339574784 wanted 23952 found 23989
Ignoring transid failure
ERROR: root [256 0] level 0 does not match 2

ERROR: errors found in fs roots
Opening filesystem to check...
Checking filesystem on /dev/mmcblk0p1
UUID: 5690ec67-0e23-4592-a381-01432a8abbb0
found 386806038528 bytes used, error(s) found
total csum bytes: 376931744
total tree bytes: 509050880
total fs tree bytes: 81920
total extent tree bytes: 100974592
btree space waste bytes: 34763056
file data blocks allocated: 5087232
 referenced 9916416

[arnogon]

And this was with --repair

[1/7] checking root items
Fixed 0 roots.
[2/7] checking extents
ref mismatch on [13631488 12288] extent item 1, found 0
data extent[13631488, 12288] bytenr mimsmatch, extent item bytenr 13631488 file item bytenr 0
data extent[13631488, 12288] referencer count mismatch (root 256 owner 414370 offset 0) wanted 1 have 0
backpointer mismatch on [13631488 12288]
owner ref check failed [13631488 12288]
parent transid verify failed on 192339574784 wanted 23952 found 23989
Ignoring transid failure
ERROR: root [256 0] level 0 does not match 2

failed to repair damaged filesystem, aborting

[Steven Shiau]

In that case, I believe when saving, the image was broken.
Sorry for that. Btrfs does change very fast, so...

Steven