How to exclude other filesystems but include subvolumes?

Many programs like find, tar, rsync, cp, du, etc have options to exclude
other filesystems, eg rsync: 
  --one-file-system, -x    don't cross filesystem boundaries

But this also excludes subvolumes, which are in the same filesystem.

How can I address a btrfs filesystem with all subvolumes, but exclude
other filesystems?

Example: I want to copy the / filesystem (with all subvolumes), what is the
best solution (for scripting!)?


-- 
Ullrich Horlacher              Server und Virtualisierung
Rechenzentrum TIK
Universitaet Stuttgart         E-Mail: horlacher@tik.uni-stuttgart.de
Allmandring 30a                Tel:    ++49-711-68565868
70569 Stuttgart (Germany)      WWW:    https://www.tik.uni-stuttgart.de/
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