elementary d_move question

["J. Bruce Fields" <bfields@fieldses.org>]

If I rename foo over bar, while holding bar open, then
/proc/<pid>/fd/<fd> still shows me bar's old path:

	$ touch foo bar
	$ tail -f bar &
	[1] 23492
	$ mv foo bar
	$ readlink /proc/23492/fd/3
	/home/bfields/bar (deleted)

The rename does a d_move(dentry, target) where I assume dentry is for
"foo" and target for "bar", with target the same dentry that the file
descriptor holds a reference on.

But d_move() does

	switch_names(dentry, target);

giving target name "foo".  So how does readlink still get "bar"?

I've clearly missed something obvious....

--b.