Hi,
I find myself caught between two traditions.
On the one hand, the radix tree has been calling the page cache dirty &
writeback bits "tags" for over a decade.
On the other hand, using some of the bits _in a pointer_ as a tag has been
common practice since at least the 1960s.
https://en.wikipedia.org/wiki/Tagged_pointer and
https://en.wikipedia.org/wiki/31-bit
EROFS wants to use tagged pointers in the radix tree / xarray. Right now,
they're building them by hand, which is predictably grotty-looking.
I think it's reasonable to provide this functionality as part of the
XArray API, _but_ it's confusing to have two different things called tags.
I've done my best to document my way around this, but if we want to rename
the things that the radix tree called tags to avoid the problem entirely,
now is the time to do it. Anybody got a Good Idea?