viced: prevent writes on readonly fileservers
Currently, a fileserver can be initialized as readonly. In this mode,
writes on this server should not be allowed. Unfortunately, updates on
files stored by readonly fileservers are not completely prevented. In
some situations, the check for RO server is omitted (e.g. if the user is
the owner of the file to be updated). In other situations, the same
check is redundant.
To fix these problems, consolidate this check in one place.
Change-Id: Id53e15216404dfe691a87c7b4964ff08924c262c
Reviewed-on: https://gerrit.openafs.org/13934
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: Benjamin Kaduk <kaduk@mit.edu>