Since 5.10 kernel there is a new feature called fast_commit. In arch wiki https://wiki.archlinux.org/title/ext4 you can read that it can be enabled in existing filesystem with:

tune2fs -O fast_commit /dev/drivepartition

but in https://lwn.net/Articles/842385/ there is:

Fast commits are activated at filesystem creation time, so users will have to recreate their filesystems to use this feature.

So is tune2fs -O fast_commit truly enable this feature in existing filesystem ?

1 Answer 1


tune2fs -O fast_commit is supported since e2fsprogs 1.46.0, which was released two weeks after the LWN article was published. So the article was correct at the time of publication, and the Arch wiki is correct now.

tune2fs -O fast_commit doesn’t just set the corresponding flag, it creates all the required data structures; the required functions were added in late January 2021, and tune2fs was then updated to use them. You can run it even on a mounted system, and check with dumpe2fs that the feature was indeed enabled (look for “Fast commit length” and check that it’s non-zero).

  • Thank you. Seems it works: Fast commit length: 256
    – EdiD
    Commented Nov 25, 2021 at 10:51

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