On Fri, Jan 22, 2016 at 03:35:33PM -0500, Cole Robinson wrote:
> On 01/22/2016 02:35 PM, Kashyap Chamarthy wrote:
> > On Fri, Jan 22, 2016 at 03:56:08PM +0000, Daniel P. Berrange wrote:
> >> We have had virtlockd available for a long time now but
> >> have always defaulted to the 'nop' lock driver which does
> >> no locking. This gives users an unsafe deployment by
> >> default unless they know to turn on lockd. virtlockd will
> >> auto-activate via systemd when guests launch, so setting
> >> it on by default will only cause upgrade pain for people
> >> on non-systemd distros.
> >
> > I tried to test this patch in the below way after applying to my local
> > Git master, and my test seems to fail.
My mistake - test was failing because I missed to start 'virtlogd'
daemon _before_ libvirtd. (Thanks, Cole, for noticing that I mixed up
'virtlogd' and 'virtlockd'.)
With that fixed, my same test succeeds[*].
ACK & Tested-By: Kashyap Chamarthy <kchamart@xxxxxxxxxx>
[*] Test
(1) Purposefully make two libvirt VMs point to the same disk image:
$ sudo ./run tools/virsh dumpxml cvm1 | grep 'source file'
<source file='/var/lib/libvirt/images/cirros-0.3.3-x86_64-disk.img'/>
$ sudo ./run tools/virsh dumpxml cvm2 | grep 'source file'
<source file='/var/lib/libvirt/images/cirros-0.3.3-x86_64-disk.img'/>
(2) Start the first guest (cvm1):
$ sudo ./run tools/virsh start cvm1
Domain cvm1 started
(3) Start the second guest (cvm2), the disk image is locked, and libvirt,
correctly, refuses to start it:
$ sudo ./run tools/virsh start cvm2
error: Failed to start domain cvm2
error: resource busy: Lockspace resource
'/var/lib/libvirt/images/cirros-0.3.3-x86_64-disk.img' is locked
And, an appropriate error is thrown in libvirt debug log:
...
2016-01-22 21:56:19.095+0000: 3008: error : virLockSpaceAcquireResource:640 : resource busy: Lockspace resource '/var/lib/libvirt/images/cirros-0.3.3-x86_64-disk.img' is locked
...
[...]
> > Enable `virtlockd` for the QEMU driver:
> >
> > $ augtool -s set /files/etc/libvirt/qemu.conf/lock_manager lockd
> >
> > Invoke just compiled virtlockd and libvirtd (in that order):
> >
> > $ sudo ./run src/virtlockd &
Noting for completeness, I missed a step here: starting the virtlogd
daemon _before_ libvirtd
$ sudo ./run src/virtlogd &
(Just remembered that recently a patch (a8bb330) was merged that made it
mandatory to have virtlogd start _before_ libvirtd, because: "In the
non-systemd case, without socket activation, we need to proper
ordering.")
> > $ sudo ./run daemon/libvirtd &
[...]
> You're mixing up virtlogd and virtlockd :) virtlogd was added recently
> and should be started. But maybe there's another issue if it wasn't
> started automatically.
Duh, that's embarassing, you're of course right. Thanks for catching
that. After starting the 'virtlogd' daemon, all is good.
--
/kashyap
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