I tested quota reporting against a Win8 Server via cifs-utils 6.0 (on a Fedora box) with SMB2.0 and it's not quite what one might expect.
It glitches on the Used column returning what on the test server system looks
to be the remaining free space on the drive overall. Guessing that it
is the result of mixing folder and drive sizes in the likely
calculation totalsize - freespace = used. In this case the "folder"
total size approaches zero (100M) and the free space is the figure at
drive level not folder..hence the negative value below.
sudo mount -t cifs //testserver/test mnt/ --verbose -ouser=zzalsmf3,domain
Filesystem Size Used Avail Use% Mounted on
//126.96.36.199/test 100M -160G 50M 101% /home/matt/mnt/isilon
I don't consider this a bug. statfs() reports information about the drive at large, not information about the amount available to a specific user. This info is better presented via the quota tools, but that will require some VFS layer work since the quota API currently operates on block devices.
cc'ing Sachin since he was looking at this a while back...
...also, this a kernel problem, not a userland one...
*** This bug has been marked as a duplicate of bug 9281 ***