[libvirt] [PATCH] qemu: Update a domain's persistent definition file if it's defined

[John Ferlan]

On 12/20/18 4:06 AM, Wang Yechao wrote:
> From: Li XueLei <li.xuelei1 at zte.com.cn>
> 
> During making disk snapshot in an active domain, sometimes we
> should update the domain's persistent definition.We must check if
> the domain is defined, before we update the persistent definition
> file.
> First,we create a vm.Then,define the vm and undefine the vm.Last create a 
> --memspec snapshot for the vm.Now,we will find a persistent definition
> file in the config directory if we don't use this patch.

The formatting is all off, rewritten to make it a bit easier:

During making disk snapshot in an active domain, sometimes we should
update the domain's persistent definition.

We must check if the domain is defined, before we update the persistent
definition file.

First, we create a vm.

Then, define the vm and undefine the vm.

Last create a --memspec snapshot for the vm.

Now, we will find a persistent definition file in the config directory
if we don't use this patch.

...

So I think what you're trying to point out is there is an edge condition
whereby if an active domain is undefined, then it's possible that the
qemuDomainSnapshotCreateDiskActive would call virDomainSaveConfig thus
recreating the domain.

Is that about right?

> 
> Signed-off-by: Li XueLei <li.xuelei1 at zte.com.cn>
> ---
>  src/qemu/qemu_driver.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index e32257f..94dcb97 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -15330,7 +15330,7 @@ qemuDomainSnapshotCreateDiskActive(virQEMUDriverPtr driver,
>  
>      if (ret == 0 || !do_transaction) {
>          if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm, driver->caps) < 0 ||
> -            (persist && virDomainSaveConfig(cfg->configDir, driver->caps,
> +            (vm->persistent && persist && virDomainSaveConfig(cfg->configDir, driver->caps,
>                                              vm->newDef) < 0))

Wrong indention here. The vm->newDef would need to align under the cfg->
or you could put the virDomainSaveConfig on the next line aligned under
the vm->persistent.

I'll need to look a bit more or hope that perhaps Peter sees this and
has some quick advice.

John

>              ret = -1;
>      }
>