chmod (as root) gets "permission denied"

[Gab]

I'm running Ubuntu 12.04 LTS
Release: 12.04

My posixovl version:

fuse-posixovl:
  Installed: 1.2~20100321+git4224970-1
  Candidate: 1.2~20100321+git4224970-1

I've mounted as a root a posixovl directory over a cifs directory that doesn't handle file permissions.
My cifs fstab mount:
//file-server/gabriele /mnt/file-server cifs noauto,noperm,nounix,noserverino,mapchars,user=**,password=**,sec=ntlm,users 0 0

my posixovl mount commands (i've tried them all)
# mount.posixovl /mnt/fileserver/subdir
# mount.posixovl -F /mnt/fileserver/subdir

if I

# cd /mnt/fileserver/subdir
# touch testfile
# chmod g+w testfile

I get a:
chmod: changing permissions of `testfile': Permission denied

though i'm successfully able to chown. I mounted the cifs fliesysem and the posixovl as root.

[Gab (contini-mailing)]

A workaround I have just found:
if i mount the filesystem with the undocumented option:

# mount.posixovl -1 /mnt/fileserver/subdir

i'm able to chmod on mounted file system.
Reading the source i've learnt the magic option enables the "single thread" mode. Maybe it has performance issues, but at least it is usable now.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.