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@redhat.com> [*] 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