linux-ext4 - ext4 online resize -> EXT4-fs error (device loop0) in ext4_update_backup

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Date:   Wed, 26 Oct 2022 19:49:56 +0000
From:   "Unterwurzacher, Jakob" <jakob.unterwurzacher@...obroma-systems.com>
To:     "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Schulz, Quentin" <quentin.schulz@...obroma-systems.com>
Subject: ext4 online resize -> EXT4-fs error (device loop0) in
 ext4_update_backup_sb:174: Filesystem failed CRC

Hi,

it looks like I am hitting a similar issue as reported by Borislav Petkov
in April 2022 ( https://lore.kernel.org/lkml/YmqOqGKajOOx90ZY@zn.tnic/ ).

I'm on kernel 6.0.5 and see this on arm64 as well as x86_64.
I have a 100% reproducer using a loop mount, here it is:

	truncate -s 16g ext4.img
	mkfs.ext4 ext4.img 500m
	mkdir ext4.mnt
	mount ext4.img ext4.mnt
	resize2fs ext4.img

And these are the kernel messages it generates:

	[   33.774267] loop0: detected capacity change from 0 to 33554432
	[   33.796319] EXT4-fs (loop0): mounted filesystem with ordered data mode. Quota mode: none.
	[   33.796518] ext4 filesystem being mounted at /root/ext4.mnt supports timestamps until 2038 (0x7fffffff)
	[   33.799324] EXT4-fs (loop0): resizing filesystem from 512000 to 16777216 blocks
	[   33.933110] EXT4-fs (loop0): resized filesystem to 16777216
	[   33.965633] EXT4-fs (loop0): Invalid checksum for backup superblock 8193

	[   33.965675] EXT4-fs error (device loop0) in ext4_update_backup_sb:174: Filesystem failed CRC
	[   33.965884] EXT4-fs (loop0): Invalid checksum for backup superblock 24577

	[   33.965902] EXT4-fs error (device loop0) in ext4_update_backup_sb:174: Filesystem failed CRC
	[   33.966058] EXT4-fs (loop0): Invalid checksum for backup superblock 40961

	[   33.966075] EXT4-fs error (device loop0) in ext4_update_backup_sb:174: Filesystem failed CRC
	[   33.966225] EXT4-fs (loop0): Invalid checksum for backup superblock 57345

	[   33.966242] EXT4-fs error (device loop0) in ext4_update_backup_sb:174: Filesystem failed CRC
	[   33.966398] EXT4-fs (loop0): Invalid checksum for backup superblock 73729

	[   33.966415] EXT4-fs error (device loop0) in ext4_update_backup_sb:174: Filesystem failed CRC
	[   33.966557] EXT4-fs (loop0): Invalid checksum for backup superblock 204801

	[   33.966574] EXT4-fs error (device loop0) in ext4_update_backup_sb:174: Filesystem failed CRC
	[   33.966765] EXT4-fs (loop0): Invalid checksum for backup superblock 221185

	[   33.966784] EXT4-fs error (device loop0) in ext4_update_backup_sb:174: Filesystem failed CRC
	[   33.966946] EXT4-fs error (device loop0) in ext4_update_backup_sb:174: Filesystem failed CRC
	[   33.967074] EXT4-fs error (device loop0) in ext4_update_backup_sb:174: Filesystem failed CRC
	[   33.967237] EXT4-fs error (device loop0) in ext4_update_backup_sb:174: Filesystem failed CRC

e2fsck seems mostly happy, should I be concerned?

	e2fsck ext4.img 

	e2fsck 1.46.2 (28-Feb-2021)
	ext4.img contains a file system with errors, check forced.
	Pass 1: Checking inodes, blocks, and sizes
	Pass 2: Checking directory structure
	Pass 3: Checking directory connectivity
	Pass 4: Checking reference counts
	Pass 5: Checking group summary information
	ext4.img: 11/4161536 files (0.0% non-contiguous), 536410/16777216 blocks

Thank you,
Jakob