Deleting subvolumes - there be dragons

I just read this article here: https://lwn.net/Articles/579009/ which states:

---------------------------------
btrfs subvolume delete path

For ordinary subvolumes (as opposed to snapshots, described below),
the subvolume indicated by path must be empty before it can be deleted.
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So I gave it a try:

$ sudo btrfs subvolume create /home2
$ sudo mkdir /home2/lalala
< copy a random pdf file into /home2/lalala) >
$ sudo btrfs subvolume delete /home2

And boom! It's all gone!
Even though subvolume was not empty.

So apart from the fact that it looks like the article is wrong here, it seems very dangerous to me that one simple command can nuke an entire volume, even if it's full of files and folders.

Of course I'm new to btrfs so maybe I'm reading something wrong. If so, then please do set me straight.

As you have found, that's not correct. In fact, there's a couple of
potentially misleading things in that article, just from skimming the first few paragraphs...

You can do the same thing with rm -rf on any filesystem. So yes,
it's a dangerous command, and you need to be sure you want to run it.

No, I think the author of the article is just mistaken.

Hugo.

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That's not correct, but maybe the author meant that a subvolume you intend to delete must not contain another subvolume. A subvolume in another subvolume will anchor the parent.

Chris Murphy