atomic renames on freebsd w/ softupdates, was Re: djblinux?

* Laurent Bercot:

> I'm seriously considering a BSD kernel... as well as a Linux kernel,
> a Solaris kernel (except it isn't free), ... you name it.

this is a little OT here, but there's one thing bernstein relies on
which is not entirely true:  atomic renames of files.  for example
freebsds soft-updates keep meta-data about a particular file-system
consistent (not as a journaling fs does, but softupdates guarantee
that writes come one after the other, in order, no jumping around).

i undertand that since djb software, especially large qmail server
installations evokes the need to limit renames to only one at a time
per fs.  the djb software style needs atomic renames all over the
place, and this disturbs me.  do other freebsd'ers on this list know
more about this?

  clemens