On Fri, Jan 17, 2020 at 08:36:16AM -0800, Omar Sandoval wrote: > The semantics I implemented in my series were basically "linkat with > AT_REPLACE replaces the target iff rename would replace the target". > Therefore, symlinks are replaced, not followed, and mountpoints get > EXDEV. In my opinion that's both sane and unsurprising. Umm... EXDEV in rename() comes when _parents_ are on different mounts. rename() over a mountpoint is EBUSY if it has mounts in caller's namespace, but it succeeds (and detaches all mounts on the victim in any namespaces) otherwise. When are you returning EXDEV? Incidentally, mounts _are_ traversed on the link source, so what should that variant do when /tmp/foo is a mountpoint and you feed it "/tmp/foo" both for source and target?
