CIFS mount incorrect disk space

I defined a new samba mount in an ubuntu VM via /etc/fstab

//x.x.x.x/share  /share  cifs  credentials=/.smbcreds,uid=1000,gid=1000,vers=3.0  0  0

With this I get the following output from df -h

filesystem       Size   Used  Avail  Use%  Mounted On
//x.x.x.x/share  5.0G   79M   5.0G   2%    /share
...

This is a ZFS share on the host and I am using samba to expose it here. I would expect to see about 12TB of free space, which is what I see if I run df -u on the samba host. Running du -f --max-depth=1 in the ubuntu VM reports this:

2.2T   /share
...

Which is the correct usage for the mount. Ultimately I am having issues where services are trying to write files to the mount that are larger than the total reported filesystem space and they fail since they do a check on available space before writing.