alternative attach names are a great idea for administating a
fileserver...  you can kick of dumps or halt the filesystem with a ctl
file...  way better than a ctl pipe and also provides a back channel
with proper perm checking...  i see no problem in providing filsystem
command for renaming/moving files between directories there too...  it
is just impossible to make use of this from mv because of the
mount/bind indirections/multiple filesystems per server ect.  you cant
figure out if the ctl file you have really belongs to that file system
of the file you are refering to or figure out the attach name of the
filesystem of any random file... there might be a exportfs in between
ect...

the only proper way to implement inter directory renames accessible
from mv command is with a 9p protocol change.

maybe we can live with a special fscmd and let the user figure out
the right filsys name and path? we can make the command format
and naming compatible so it works consistently with kfs, cwfs and
kenfs.

--
cinap