On 2023-01-24 17:20, Mike Frysinger wrote:
> i'd like to require that the mv be
> atomic when relocating a directory, and if it isn't, fallback to other
> logic

Calling the new option "--one-file-system" sounds a bit wrong, as 
--one-file-system is for programs like 'du' and 'cp' and causes them to 
not cross a file system boundary when recursing - something that 'mv' 
could also do (when it falls back on copying), but which is a different 
thing than what you're asking for.

How about if we call the new option --no-copy instead? Something like 
the attached incomplete patch, say. (It needs more documentation and 
ideally a test case.)