lxc.mount.entry should support all the bdev modules

[xaionaro]

Hello.

I've faced with a problem of using squashfs image a rootfs for containers. However, if I'm adding something like:

lxc.mount.entry = /srv/lxc/.storage/sdb1/roots.squashfs/containertype_rootfs.sqsh /srv/lxc/container_name/rootfs squashfs ro,loop 0 0

I'm getting an error:

# lxc-start -n container
lxc-start: Block device required - failed to mount '/srv/lxc/.storage/sdb1/roots.squashfs/containertype_rootfs.sqsh' on '/usr/lib/x86_64-linux-gnu/lxc/./'
lxc-start: failed to setup the mount entries for 'container'
lxc-start: failed to setup the container
lxc-start: invalid sequence number 1. expected 2
lxc-start: failed to spawn 'container'

The problem is that LXC doesn't use intermediate loop-devices to mount squashfs images:

mount(
        "/srv/lxc/.storage/sdb1/roots.squashfs/containertype.sqsh",
        "/usr/lib/x86_64-linux-gnu/lxc/",
        "squashfs",
        MS_RDONLY,
        "loop" 
) = -1 ENOTBLK (Block device required)

Here's the mount() call of "mount"-utility for squashfs image:

mount("/dev/loop0", "/mnt/test", "squashfs", MS_MGC_VAL, NULL) = 0

[stgraber]

We have support for loop devices in the rootfs mounting code but apparently not for extra mount entries...

For the time being, you best bet would be to use a hook and do a manual mount in there.

[alphaonex86]

Same here, same feature needed