Re: Unmountable / uncheckable Fedora 34 btrfs: failed to read block groups: -5 open_ctree failed

["Niccolò Belli" <darkbasic@linuxsystems.it>]

Il 2021-09-12 15:35 Qu Wenruo ha scritto:
> My bad, the commit is 2b29726c473b ("btrfs: rescue: allow ibadroots to
> skip bad extent tree when reading block group items"), which is only
> merged into the incoming v5.15-rc1.

I've compiled linux-git master and tried again:

$ uname -a
Linux arch-laptop 5.14.0-1-git-11152-g78e709522d2c #1 SMP PREEMPT Sun, 
12 Sep 2021 12:53:13 +0000 x86_64 GNU/Linux

$ sudo mount -o ro,rescue=ibadroots 
/run/media/niko/3ea0705c-21c9-4ba9-80ee-5a511cb2a093/nvme0n1p6.img.copy 
/mnt2/
mount: /mnt2: can't read superblock on /dev/loop0.

[  196.277414] loop: module loaded
[  196.278228] loop0: detected capacity change from 0 to 207618048
[  196.736456] BTRFS: device label fedora_localhost-live devid 1 transid 
1029644 /dev/loop0 scanned by mount (2730)
[  196.736819] BTRFS info (device loop0): flagging fs with big metadata 
feature
[  196.736825] BTRFS info (device loop0): ignoring bad roots
[  196.736826] BTRFS info (device loop0): disk space caching is enabled
[  196.736827] BTRFS info (device loop0): has skinny extents
[  197.408704] BTRFS warning (device loop0): checksum verify failed on 
21348679680 wanted 0xd05bf9be found 0x2874489b level 1
[  197.408843] BTRFS info (device loop0): start tree-log replay
[  197.408847] BTRFS warning (device loop0): log replay required on RO 
media
[  197.409458] BTRFS error (device loop0): open_ctree failed

So I've added nologreplay and it did the trick:

$ sudo mount -o ro,rescue=nologreplay:ibadroots 
/run/media/niko/3ea0705c-21c9-4ba9-80ee-5a511cb2a093/nvme0n1p6.img.copy 
/mnt2/

[  416.913016] loop0: detected capacity change from 0 to 207618048
[  416.918895] BTRFS info (device loop0): flagging fs with big metadata 
feature
[  416.918903] BTRFS info (device loop0): disabling log replay at mount 
time
[  416.918905] BTRFS info (device loop0): ignoring bad roots
[  416.918907] BTRFS info (device loop0): disk space caching is enabled
[  416.918908] BTRFS info (device loop0): has skinny extents
[  416.929887] BTRFS warning (device loop0): checksum verify failed on 
21348679680 wanted 0xd05bf9be found 0x2874489b level 1

$ sudo btrfs subvolume list /mnt2 | grep -v snapshot | grep -v docker
ID 256 gen 1029644 top level 5 path home
ID 265 gen 1029641 top level 256 path home/niko/.cache
ID 912 gen 1029406 top level 5 path images
ID 2428 gen 359129 top level 5 path var
ID 2429 gen 1026054 top level 2428 path var/tmp
ID 2430 gen 1029044 top level 2428 path var/cache
ID 2433 gen 1029641 top level 5 path root
ID 2653 gen 1029641 top level 5 path avd

$ ls -al /mnt2
totale 16
drwxr-xr-x 1 root root  58 16 giu 19.09 .
drwxr-xr-x 1 root root 198 12 set 17.50 ..
drwxr-xr-x 1 niko niko  72 26 ago 10.22 avd
drwxr-xr-x 1 root root  28 16 apr 10.25 home
drwxrwxrwx 1 niko niko  96 20 ago 17.23 images
dr-xr-xr-x 1 root root 196 24 ago 14.58 root
drwxr-xr-x 1 root root  28 16 apr 10.21 snapshots
drwxr-xr-x 1 root root  16 13 giu 00.10 var

Apart from backing my files up, what else should I be able to do at this 
point?

I've tried scrubbing but it's a no go:

$ sudo btrfs scrub start /dev/loop0
scrub started on /dev/loop0, fsid d3d387d6-eb5e-4b4b-9a9c-581d74fb56b4 
(pid=3255)

$ sudo btrfs scrub status /dev/loop0
UUID:             d3d387d6-eb5e-4b4b-9a9c-581d74fb56b4
Scrub started:    Sun Sep 12 18:00:30 2021
Status:           aborted
Duration:         0:00:00
Total to scrub:   97.27GiB
Rate:             0.00B/s
Error summary:    no errors found

Any chance to recover the partition?

Niccolò