btrfs replace interrupted + corruptes fs

[Samuel Greiner <samuel@balkonien.org>]

Dear folks,

I have the feeling of being in trouble.

I have a btrfs fs upon 4 HDs. 1 HD should be replaced.

1. I issued the btrfs replace command, but got the message, that the 
target HD is mounted (it was not, it did not appear in the mount output).

2. I did a system reboot in hope to do a successfull replace. The system 
did not start but said, that it could not mount the btrfs fs because of 
a missing device.

3. I booted GParted Live to investigate further.

3.1 A mount -o degraded,rescue=usebackuproot,ro failed.
In dmesg I get the following errors

flagging fs with big metadata feature
allowing degraded mounts
trying to use backup root at mount time
disk space caching is enabled
has skinny extents
bdev /dev/sda errs: wr 755, rd 0, flush 0, corrupt 0, gen 0
bdev /dev/sdd1 errs: wr 7601141, rd  3801840, flush 12, corrupt 3755, 
gen 245
replace devid present without n active replace item
failed to init dev_replace -117
open_ctree failed

4. btrfs check runs through without error

-> I guess even if i was prompted the message, that the target device of 
the btrfs replace was mounted the replace was started. Due to the reboot 
now there seems to be errors in the filesystem additional to an replace 
which i cannot stop, because i can't mount the filesystem.

Right now I have a btrfs check --check-data-csum running in hope to get 
the errors fixed.

But actionally I really don't know how to deal with that situation.

Do you have any recommondations?


Thank you very much!
Samuel


Additional info:

I'm on an recent debian bullseye. But I can't run uname -r because right 
now I'm on the GParted (1.4.0-5) Live-System.

btrfs fi show /dev/sdd1
Label: 'Data' uuid:
     Total devices 4 FS bytes used 6.59 TiB
     devid 1 size 3.65 TiB used 3.39 TiB path /dev/sdd1
     devid 2 size 2.73 TiB used 2.49 TiB path /dev/sdb1
     devid 3 size 5.46 TiB used 2.11 TiB path /dev/sdc1
     devid 1 size 5.46 TiB used 5.21 TiB path /dev/sdd1