Description
Can not set write policy of filesystem as immediate for lxc guest from virt-manager GUI

Version:
virt-manager-0.10.0-8.el7.noarch

How reproducible:
100%

Steps to Reproduce:
1: #virt-manager --connect lxc:///

2: open lxc guest via virt-manager,make sure the vm in shutdown status,attached the detailed steps of creating lxc guest in additional info B.

3: switch to hardware detail page,click add Hardware button

4: select Filesystem in left panel, input source path(the path of host,e.g. /tmp),input target path(the path of guest,e.g. /mnt),choose write policy as "immediate".

5: click Finish,click Apply

6: start the guest,check the xml of the guest,the write policy is "default" instead of "immediate",also write policy shows as "default" from virt-manager GUI.
# virsh -c lxc:/// dumpxml $gueset
    <filesystem type='mount' accessmode='passthrough'>
      <source dir='/tmp'/>
      <target dir='/mnt'/>
    </filesystem>


Actual results：
As description.

Expected results:
The write policy of lxc guest can be set as "immediate" from virt-manager GUI.

Additional info:
A.If I add the below line in guest xml,then boot the guest,write policy shows as "immediate" from virt-manager GUI.
    <driver type='path' wrpolicy='immediate'/>

B.Attach the detailed steps to create a lxc guest.
1. add the following yum repo
#vim /etc/yum.repos.d/yum-fedora.conf
[main]
cachedir=/var/cache/yum/$basearch/$releaseverkeepcache=0
debuglevel=2
logfile=/var/log/yum.log
exactarch=1
obsoletes=1
gpgcheck=1
plugins=1
installonly_limit=3

[fedora]
name=Fedora $releasever - $basearch failovermethod=priority
#baseurl=http://download.fedoraproject.org/pub/fedora/linux/releases/$releasever/Everything/$basearch/os/
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=fedora-$releasever&arch=$basearch
enabled=1
metadata_expire=7d
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$releasever-$basearch

[updates]
name=Fedora $releasever - $basearch - Updates failovermethod=priority
#baseurl=http://download.fedoraproject.org/pub/fedora/linux/updates/$releasever/$basearch/
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=updates-released-f$releasever&arch=$basearch
enabled=1
gpgcheck=1

2.#yum -y --nogpg --releasever=19 --config=/etc/yum.repos.d/yum-fedora.conf --installroot=/var/lib/libvirt/filesystems/f19x86_64 --disablerepo='*' --enablerepo=fedora  install  systemd passwd yum redhat-release vim-minimal openssh-server procps

3. #echo "pts/0" >> /var/lib/libvirt/filesystems/f19x86_64/etc/securetty

4. #vi /var/lib/libvirt/filesystems/f19x86_64/etc/pam.d/login
 commnent out the following lines
#session    required     pam_selinux.so close
#session    required     pam_loginuid.so

5.add root user and the passwd.
#chroot /var/lib/libvirt/filesystems/f19x86_64 /bin/passwd root

6. Launch virt-manager
#virt-manager

7.Click "Create a new virtual machine"

8.input vm name,select "Localhost(LXC)" in "Connetion"

9.select "operating system container" and click "Forward"

10.Browse to path of rootfs.fedora,in this case is /var/lib/libvirt/filesystems/f19x86_64

11.set Memory and cpu ,and click "Forward"

12.click "Advanced options", click "Finish"