[libvirt] [PATCH v2 6/6] qemu: Fetch pr-helper process info on reconnect

[Peter Krempa]

On Thu, Jul 05, 2018 at 09:44:38 +0200, Michal Privoznik wrote:
> If qemu-pr-helper process died while libvirtd was not running no
> event is emitted. Therefore, when reconnecting to the monitor we
> must check the qemu-pr-helper process status and act accordingly.
> 
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>  src/qemu/qemu_process.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 61 insertions(+)
> 
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index ac2f73c99e..b6db337e76 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -2071,6 +2071,64 @@ qemuRefreshVirtioChannelState(virQEMUDriverPtr driver,
>      return ret;
>  }
>  
> +
> +static int
> +qemuProcessRefreshPRManagerState(virDomainObjPtr vm,
> +                                 virHashTablePtr info)
> +{
> +    qemuDomainObjPrivatePtr priv = vm->privateData;
> +    qemuMonitorPRManagerInfoPtr prManagerInfo;
> +    const char *managedAlias = qemuDomainGetManagedPRAlias();
> +    int ret = -1;
> +
> +    if (!(prManagerInfo = virHashLookup(info, managedAlias))) {
> +        virReportError(VIR_ERR_OPERATION_FAILED,
> +                       _("missing info on pr-manager %s"),
> +                       managedAlias);
> +        goto cleanup;
> +    }
> +
> +    priv->prDaemonRunning = prManagerInfo->connected;
> +
> +    if (!priv->prDaemonRunning &&
> +        virDomainDefHasManagedPR(vm->def) &&

You can assume this since you already checked in the caller.

> +        qemuProcessStartManagedPRDaemon(vm) < 0)
> +        goto cleanup;
> +
> +    ret = 0;
> + cleanup:
> +    return ret;
> +}
> +
> +
> +static int
> +qemuRefreshPRManagerState(virQEMUDriverPtr driver,
> +                          virDomainObjPtr vm)
> +{
> +    qemuDomainObjPrivatePtr priv = vm->privateData;
> +    virHashTablePtr info = NULL;
> +    int ret = -1;
> +
> +    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_PR_MANAGER_HELPER) ||
> +        !virDomainDefHasManagedPR(vm->def))
> +        return 0;
> +
> +    qemuDomainObjEnterMonitor(driver, vm);
> +    ret = qemuMonitorGetPRManagerInfo(priv->mon, &info);
> +    if (qemuDomainObjExitMonitor(driver, vm) < 0)
> +        ret = -1;
> +
> +    if (ret < 0)
> +        goto cleanup;
> +
> +    ret = qemuProcessRefreshPRManagerState(vm, info);
> +
> + cleanup:
> +    virHashFree(info);
> +    return ret;
> +}
> +
> +
>  static void
>  qemuRefreshRTC(virQEMUDriverPtr driver,
>                 virDomainObjPtr vm)
> @@ -7724,6 +7782,9 @@ qemuProcessReconnect(void *opaque)
>      if (qemuRefreshVirtioChannelState(driver, obj, QEMU_ASYNC_JOB_NONE) < 0)
>          goto error;
>  
> +    if (qemuRefreshPRManagerState(driver, obj) < 0)
> +        goto error;

This is executed prior to qemuProcessUpdateDevices and thus if a disk
detach with the PR manager succeeds during the time libvirtd was gone
the above code will not be able to find the correct state and will kill
the VM.

> +
>      /* If querying of guest's RTC failed, report error, but do not kill the domain. */
>      qemuRefreshRTC(driver, obj);

ACK if you move it to the correct place and simplify the restarting
code.

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