Re: Upgraded from Buster to Bullseye, unmountable Btrfs filesystem

On 2021/11/11 21:55, S. wrote:

On 11/11/21 02:11, Qu Wenruo wrote:

quoted

quoted

root@OpenMediaVault:~# dd if=/dev/sda3 of=/tmp/mirror1 bs=1 count=16k
skip=149487616
16384+0 records in
16384+0 records out
16384 bytes (16 kB, 16 KiB) copied, 0.305711 s, 53.6 kB/s

My bad, this copy should be from /dev/sdb2, not /dev/sda3.

No wonder both copy doesn't match.

Hi, I really appreciate your help to fix this. I am attaching the new
`mirror1` image, generated like this:

------------------------
root@OpenMediaVault:~# dd if=/dev/sdb2 of=/tmp/mirror1 bs=1 count=16k

You missed the "skip=" parameter.

16384+0 records in
16384+0 records out
16384 bytes (16 kB, 16 KiB) copied, 0.274943 s, 59.6 kB/s
root@OpenMediaVault:~# rsync -avh /tmp/mirror1
sully@192.168.1.14:/home/sully/Desktop/
Password:
sending incremental file list
mirror1

sent 16.49K bytes  received 35 bytes  3.67K bytes/sec
total size is 16.38K  speedup is 0.99
------------------------

quoted

# dd if=mirror2 of=/dev/sdb2 bs=1 count=16k skip=149487616
# dd if=mirror2 of=/dev/sda3 bs=1 count=16k skip=170459136

All my bad.

The correct command line should be:

# dd if=mirror2 of=/dev/sdb2 bs=1 count=16k seek=149487616
# dd if=mirror2 of=/dev/sda3 bs=1 count=16k seek=170459136

Thankfully, even with the wrong command, btrfs has enough space reserved
at its beginning, so your fs is still untouched and very safe.

Thanks,
Qu

After writing out your fixed `mirror2` image with the above commands I
get these dmesg errors when attempting to mount it:

-------------------------
[   28.859193] BTRFS info (device sda3): flagging fs with big metadata
feature
[   28.866209] BTRFS info (device sda3): disk space caching is enabled
[   28.872507] BTRFS info (device sda3): has skinny extents
[   29.053000] BTRFS critical (device sda3): corrupt leaf: root=9
block=170459136 slot=0, invalid key objectid, have 1101835439474057344
expect to be aligned to 4096
[   29.067527] BTRFS error (device sda3): block=170459136 read time tree
block corruption detected
[   29.120141] BTRFS critical (device sda3): corrupt leaf: root=9
block=170459136 slot=0, invalid key objectid, have 1101835439474057344
expect to be aligned to 4096
[   29.134781] BTRFS error (device sda3): block=170459136 read time tree
block corruption detected
[   29.143568] BTRFS warning (device sda3): failed to read root
(objectid=9): -5
[   29.239873] BTRFS error (device sda3): open_ctree failed
-------------------------

Please let me know if you need anything else. Thanks a lot!