storaged: btrfs: show btrfs filesystem "root" subvolume as "top-level"

[jelly]

Showing this as "/" confuses users as they might think it is the root partition and official btrfs terminology names it "top-level".

https://btrfs.readthedocs.io/en/latest/Subvolumes.html

Relates: #19920

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[jelly]

If we want this italic, it might not be too easy and we have to special case it for btrfs.

[garrett]

Two different naive approaches, without much code modification:

• One passes all the names to a data attribute and CSS specifically acts upon the attribute (with a simple class selector child below it, so it won't try to match anything but a parent of the class, instead of everything): https://github.com/cockpit-project/cockpit/commit/b33a5121ebed605de42385e3aa08a2788cd9d256

• The other explicitly only handles "top-level" and sets a class: https://github.com/cockpit-project/cockpit/commit/3a660b1a6178ebad6c81e4e5b936ed5c35091c8e

This is assuming that "name" is not translated here, however, and that subvolumes are not able to be called "top-level" manually, and that someone has done so.

Is this the best way to do it? I'm sure it's not. It's a way without modifying anything. It might spark some other idea too (perhaps a better way to determine this, as you know the code better), so I'm sharing it.

[garrett]

It's still in English as "top-level", at least in https://wiki.debianforum.de/Btrfs :

[jelly]

And anaconda PR https://github.com/rhinstaller/anaconda-webui/pull/492