Try these... assuming selinux is creating the perm issue.
I had something similar problem and doing the below got it resolved.
1) getsebool virt_use_nfs
This should show this variable as on ... as in ...
virt_use_nfs --> on
If not, then go to step 2
2) setsebool virt_use_nfs 1
Do all of the above as root.
Hope that helps
thanx,
deepak