Re: [GIT PULL] ext4 updates for 5.5

From: Linus Torvalds
Date: Sat Nov 30 2019 - 14:10:37 EST

On Tue, Nov 26, 2019 at 4:53 AM Theodore Y. Ts'o <tytso@xxxxxxx> wrote:
> * Direct I/O via iomap (required the iomap-for-next branch from Darrick
> as a prereq).

I appreciate you telling me this, but why didn't you say anything at
all in the merge?

Ted, this merge commit message is simply not acceptable:

Merge branch 'iomap-for-next' into mb/dio

That's literally all you wrote about the iomap merge.

Not ok.

Merges are commits too. And merges need commit messages too. They need
an explanation of what they do - and why - the same way a normal
commit does.

You wouldn't make a one-liner "Do this" message for a regular commit
that has big implications. Why do you think it's ok for a merge

When you merge something, the individual commits that get pulled in
hopefully have their own explanations for each individual change -
otherwise you definitely shouldn't merge them. So the merge doesn't
need to replicate all of that.

But the merge itself still needs a "why am I merging these commits" explanation.

We pride ourselves on good commit messages. But that merge commit
message is pure and utter garbage.