[SOLVED] Unmountable BTRFS, and extent and rootfs check error


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Hello all,

[Solved], see below, thanks @johnnie.black

 

History

I had a problem with "Unmountable BTRFS - No filesystem" on a (almost new, installed few weeks ago) array drive. I solved it with the help of this topic: 

 

Basicaly I copy a mirror superblock to the main one.

 

root@Serveur:~# btrfs rescue super-recover -v /dev/mapper/md1 # reported all supers are valid and did not recover
root@Serveur:~# btrfs-select-super -s 1 /dev/mapper/md1 # to force using first mirror

 

The drive mounted and, despite data was already there (manually mounted with array in maintenance mode), it has been reconstructed.

 

I then btrfs scrubed it, no errors.

I have a inaccessible folder that I can't even delete.


Now I still have some unraiparable errors:

root@Serveur:~# btrfs check --repair /dev/mapper/md1
enabling repair mode
WARNING:

        Do not use --repair unless you are advised to do so by a developer
        or an experienced user, and then only after having accepted that no
        fsck can successfully repair all types of filesystem corruption. Eg.
        some software or hardware bugs can fatally damage a volume.
        The operation will start in 10 seconds.
        Use Ctrl-C to stop it.
10 9 8 7 6 5 4 3 2 1
Starting repair.
Opening filesystem to check...
Checking filesystem on /dev/mapper/md1
UUID: c262207c-8afe-4501-9ed2-522fd075f58d
[1/7] checking root items
Fixed 0 roots.
[2/7] checking extents
ref mismatch on [15044599808 131072] extent item 1, found 0
incorrect local backref count on 15044599808 root 5 owner 4996 offset 28704768 found 0 wanted 1 back 0x1730fd0
backref disk bytenr does not match extent record, bytenr=15044599808, ref bytenr=15043026944
backpointer mismatch on [15044599808 131072]
owner ref check failed [15044599808 131072]
repair deleting extent record: key [15044599808,168,131072]
Repaired extent references for 15044599808
ref mismatch on [1099503798605 131072] extent item 0, found 1
unaligned extent rec on [1099503798605 131072]
record unaligned extent record on 1099503798605 131072
No device size related problem found
[3/7] checking free space cache
cache and super generation don't match, space cache will be invalidated
[4/7] checking fs roots
root 5 inode 4996 errors 4540, bad file extent, file extent discount, nbytes wrong
Found file extent holes:
        start: 28704768, len: 131072
ERROR: errors found in fs roots
found 2487837077504 bytes used, error(s) found
total csum bytes: 2426215532
total tree bytes: 2765979648
total fs tree bytes: 6717440
total extent tree bytes: 16760832
btree space waste bytes: 283448596
file data blocks allocated: 2485070966784
 referenced 2485070966784

I need advice for the next steps to have a clean filesystem please.

 

I see several solutions:

  1. there is something more to do to recover with btrfs check --repair I'm not yet aware of
  2. use btrfs restore to copy to another drive, then reformat
  3. using unbalance to move data elsewhere, (maybe btrfs recover?), then reformat
  4. fourth answer 😆, please tell

 

Thank you for any guidance or suggestion !

 

Take care and stay at home

 

Reynald

 

 

Edited by Reynald
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Solved:

 

Here is what I did:

 

First error was reported in the gui after an unclean reboot: 

Unmountable BTRFS - No filesystem

So I mounted array in maintenance mode and did:

root@Serveur:~# btrfs rescue super-recover -v /dev/mapper/md1 # reported all supers are valid and did not recover
root@Serveur:~# btrfs-select-super -s 1 /dev/mapper/md1 # to force using first mirror

The drive mounted but has been reconstructed...

After because I still had error reported by btrfs check, I used unBalance to transfert to a healthy drive.

 

I then mounted array in maintenance mode and used:

mkdir -p /mnt/disk2/restore && mount /dev/mapper/md2 /mnt/disk2/restore
btrfs restore -v /dev/mapper/md1 /mnt/disk2/restore

It restored some other broken files.

 

Finally, I unmounted, changed filesystem to another one in GUI so drive got reformatted, and changed back to BTRFS Encrypted, and... voilà !

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  • JorgeB changed the title to [SOLVED] Unmountable BTRFS, and extent and rootfs check error

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