I just read about the "inline data" feature in EXT4, and more specifically about that answer on how to enable it.

What are the reasons why this feature isn't enabled by default in EXT4 ? I guess it's to keep the FS compatible with older kernels, that didn't support this feature yet. Are there other reasons ?

If I know that I'll never use an older kernel, is there any reason NOT to always enable this feature when formatting a partition with EXT4 ?

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    Doesn't look like the 2013 patch to add support for grub has been merged yet, so you probably don't want to enable it on the /boot FS. Jan 8 at 11:14

1 Answer 1


Answering my own question, basically just developing Stéphane Chazelas' comment :

As Theodore Ts'o (maintainer of ext4) explained in an e-mail dating back to 2019:

There are some known issues with with the inline_data feature (...).


But yeah, there is a good reason why it's not a default-enabled feature. It also generally doesn't buy you much for most file system workloads, so it hasn't been high on my priority list to fix.

So it's probably best no to enable that feature for now, unless absolutely needed.

  • There have been quite a few fixes since 2019, including to inline data, but I haven’t seen any more recent update on the actual situation of inline data support. Feb 9 at 14:10

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