[libvirt] Problems with <filesystem type='block'>

Doug Goldstein cardoe at gentoo.org
Sun Mar 3 23:24:39 UTC 2013


On Fri, Dec 21, 2012 at 10:15 PM, Lars Kellogg-Stedman <lars at oddbit.com> wrote:
> Using libvirt 1.0.1, I'm trying to start an LXC container using the
> '<filesytem type="block">' syntax, like this:
>
>     <filesystem type="block" accessmode="passthrough">
>       <source dev="/dev/vg_files/vm-foobar-root" />
>       <target dir="/" />
>     </filesystem>
>
> The specified block device exists:
>
>     # ls -lL /dev/vg_files/vm-foobar-root
>     brw-rw---- 1 root disk 253, 19 Dec 21 22:23 /dev/vg_files/vm-foobar-root
>
> If I start the domain, it appears to start without any errors...
>
>     # virsh start foobar
>     Domain foobar started
>
> ...but it's not actually running.  The log files (with loglevel=2)
> don't seem to be very interesting; this is everything from the
> instance log file:
>
> 2012-12-22 04:10:57.862+0000: starting up
> PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin LIBVIRT_DEBUG=2 LIBVIRT_LOG_OUTPUTS=2:stderr /usr/lib/libvirt/libvirt_lxc --name foobar --console 22 --security=none --handshake 25 --background --veth veth1
> 2012-12-22 04:10:57.967+0000: 1468: info : libvirt version: 1.0.1
> 2012-12-22 04:10:57.967+0000: 1468: info : lxcCapsInit:151 : No driver, not initializing security driver
> PATH=/bin:/sbin TERM=linux container=lxc-libvirt container_uuid=9041e32e-1df2-00c2-4660-dfa5b41510b7 LIBVIRT_LXC_UUID=9041e32e-1df2-00c2-4660-dfa5b41510b7 LIBVIRT_LXC_NAME=foobar /sbin/init
> 2012-12-22 04:10:58.198+0000: 1: warning : lxcContainerDropCapabilities:1788 : libcap-ng support not compiled in, unable to clear capabilities
> 2012-12-22 04:10:58.198+0000: 1493: warning : lxcControllerClearCapabilities:679 : libcap-ng support not compiled in, unable to clear capabilities
>
> Running an "strace" on the libvirtd process (strace -p <libvirtd_pid>
> -f ...), it doesn't look like libvirt is ever trying to mount the
> referenced filesystem.
>
> Is this supposed to work?  It seems like the support for having
> libvirt mount the block device is relatively recent, and I haven't had
> much luck finding examples of other folks using this capability.
>
> Thanks,
>
> -- Lars

Lars,

I just gave it a whirl. And I'm able to reproduce the same issue you
are seeing. The issue appears to be that
lxcContainerMountFsBlockAuto() is never being called. It was added in
http://www.redhat.com/archives/libvir-list/2011-August/msg00201.html
Hopefully I'll have more info soon.

-- 
Doug Goldstein




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