Identity

Kernel module: Built-in (ext4 — no separate package needed)
Userspace tools: e2fsprogs package (apt install e2fsprogs / dnf install e2fsprogs)
CLI tools: mkfs.ext4 (alias: mke2fs -t ext4), e2fsck, tune2fs, resize2fs, debugfs, dumpe2fs, blkid, findmnt
Config: /etc/fstab (mount options), no daemon config file
Logs: journalctl -k | grep ext4 (kernel messages), dmesg | grep ext4

Key Operations

Operation	Command
Check filesystem (unmounted)	`sudo e2fsck -f /dev/sdXN`
Check and auto-repair (unmounted)	`sudo e2fsck -y /dev/sdXN`
Create filesystem	`sudo mkfs.ext4 /dev/sdXN`
Create with label	`sudo mkfs.ext4 -L mylabel /dev/sdXN`
Get filesystem info	`sudo dumpe2fs /dev/sdXN \| less`
Show summary info	`sudo dumpe2fs -h /dev/sdXN`
Tune parameters	`sudo tune2fs -c 30 -i 1m /dev/sdXN`