[Lxc-users] Facing issue in Sharing host device node with container

[Datta, Souvik]

Hi,

I have created a ubuntu - precise container inside of Ubuntu host (precise).  I am trying to share a plugged in USB MSD device between host and container. In order to do so, I did a bind mount of the host device node to a fake node in the container. Following are the steps that I did:

1. Inside the container , created a file /dev/usb 
2. In the host shell executed - sudo mount --bind /dev/sdb1 /var/lib/lxc/CN/rootfs/dev/usb

After this, I went and changed the configuration file in /var/lib/lxc/CN/config to give the container access to /dev/sdb1. The changes made in the config file is:
lxc.cgroup.devices.allow = b 8:17 rwm

In the container ,  when I execute ls -al "/dev/usb", it shows the following:
brw-rw---- 1 root disk 8, 17 Jun 24 09:26 /dev/usb

In the host, when I execute - mount , along with other mount point, it shows the following:
....
/dev/sdb1 on /var/lib/lxc/CN/rootfs/dev/usb type none (rw,bind)
....

But the issue is that - Inside the container, when I am trying to mount - /dev/usb on a directory 
I get the following error - 

ubuntu at CN:~$ sudo mount /dev/usb test/
[sudo] password for ubuntu: 
mount: block device /dev/usb is write-protected, mounting read-only
mount: cannot mount block device /dev/usb read-only

Can some one please let me know if I am missing something here? It would also be very helpful , if some one can please explain the difference between the approach of sharing a device node - one in which I use "mount --bind" to share a device node, another is through the LXC config file.

Thanks and Regards,
Souvik