On 6/25/21 4:53 AM, Michal Prívozník wrote:
On 5/28/21 8:30 PM, Jim Fehlig wrote:
Hi All!
I received a bug report about virtlockd emitting an error whenever libvirtd is (re)started
May 25 15:44:31 virt81 virtlockd[7723]: Requested operation is not valid: Lockspace for path /data/libvirtd/lockspace already exists
The problem is easily reproducible with git master by enabling lockd in qemu.conf, setting file_lockspace_dir in qemu-lockd.conf, then restarting libvirtd.
If I understand the code correctly, when the qemu driver loads, it calls virLockManagerPluginNew, which dlopens lockd.so and calls drvInit, aka virLockManagerLockDaemonInit. Here the driver object is created, config loaded, and virLockManagerLockDaemonSetupLockspace is called. virLockManagerLockDaemonSetupLockspace sends virLockSpaceProtocolCreateLockSpaceArgs rpc to virtlockd, where it is dispatched to virLockSpaceProtocolDispatchCreateLockSpace. Alas we encounter the error when virLockDaemonFindLockSpace finds the existing lockspace.
I'm not really sure how to go about fixing it and fishing for opinions. virLockManagerLockDaemonSetupLockspace already has some code to handle the error
https://gitlab.com/libvirt/libvirt/-/blob/master/src/locking/lock_driver_loc...
Since libvirtd ignores VIR_ERR_OPERATION_INVALID, should virtlockd be changed to not return error in that case? It would be better if libvirtd knew it already told virtlockd to configure the lockspace and avoid needlessly doing it again.
Yeah, that would be the best. But I'm not sure we have a reliable way to store that info. I mean, what if I'd shut down libvirtd, then virtlockd and then 'rm -rf $lockDir'.
Fortunately, the RPC between virtlockd and libvirtd is considered internal enough that we can change it. We have guaranteed by the specfile that the virtlockd and libvirtd will be the same version. Therefore, I think we can add a new flag "hey, it's okay if the lockspace exists, no need to report error".
I explored this option (see attached patch) but when testing realized whatever is specified in file_lockspace_dir must be created by the user anyhow. If not, VMs fail to start # virsh start test error: Failed to start domain 'test' error: Unable to open/create resource /data/libvirtd/lockspace/de22c4bf931e7c48b49e8ca64b477d44e78a51543e534df488b05ccd08ec5caa: No such file or directory Since the user must create the lockspace, it will always exist :-).
Maybe we can change virtlockd to not report error if the lockspace exists even without the flag.
Callers are not interested in the error, so I took this approach https://listman.redhat.com/archives/libvir-list/2021-June/msg00841.html Regards, Jim