linux-ext4 - ext4 superblock checksum invalid after running resize2fs

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Date:   Tue, 3 Jan 2023 00:35:02 +0000
From:   Zsolt Murzsa <thxer@...er.hu>
To:     "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
Subject: ext4 superblock checksum invalid after running resize2fs

Hi!

I've had the same issue with twice in the last couple of days with the resize2fs online expand function. 
I have a md raid 1, with an LVM volume, which is formatted with ext4. I resized the volume (from 4T to 5T), then I ran resize2fs, which ran without error, the file system got bigger. 

After a few hours, I reset the machine (unsafely), due to some zombie processes, but after restarting, the system could not mount the filesystem.
I checked the disks, and ran some hardware checks, but I didn't find anything wrong. I thought the hard reset caused some problem.

That was the problem: "Superblock checksum does not match superblock". I tried several superblocks, e2fsck, testdisk, but nothing helped, dumpe2fs showed all the data about the superblock. 
I started to restore from a backup. 

In the meantime, I found the debugfs tool, with which I could skip the checksum check and thus see all the folders and files that I restored to a separate disk.
I replaced the two drives, recreated md RAID 1, LVM, then reformatted with ext4, started copying the data back.

I ran out of space so expanded the LV and ran resize2fs again (from 3T to 5T). It ran successfully again, the attached file system is 5T. 
Then I ran an e2fsck.

"e2fsck -n /dev/vg1/data
e2fsck 1.46.5 (30-Dec-2021)
Warning!  /dev/vg1/data is mounted.
ext2fs_open2: Superblock checksum does not match superblock
e2fsck: Superblock invalid, trying backup blocks...
e2fsck: Superblock checksum does not match superblock while trying to open /dev/vg1/data

The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem.  If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
    e2fsck -b 8193 <device>
or
    e2fsck -b 32768 <device>"

I'm shocked it happened again.
I can currently write / read the files, but it is suspicious that I will not be able to mount the filesystem again.
In the first case, I couldn't find a simple solution, but is it possible to fix the checksum somehow?
It takes a lot of time to use debugfs to copy everything to another drive and back again.

My current kernel version: 5.19.17-1-pve.
I can attach all the superblocks (Both the first and second case), or any other information, if needed. 

Best Regards,
Zsolt Murzsa