[libvirt] [PATCH 1/5] qemu: Only set group_name when actually requested

[John Ferlan]

On 01/25/2017 04:16 AM, Martin Kletzander wrote:
> We were setting it based on whether it was supported and that lead to
> setting it to NULL, which our JSON code caught.  However it ended up
> producing the following results:
> 
>  $ virsh blkdeviotune fedora vda --total-bytes-sec-max 2000
>  error: Unable to change block I/O throttle
>  error: internal error: argument key 'group' must not have null value
> 
> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
> ---
>  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 516a851d3d55..f45972e3c823 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -17506,7 +17506,7 @@ qemuDomainSetBlockIoTune(virDomainPtr dom,
>          qemuDomainObjEnterMonitor(driver, vm);
>          ret = qemuMonitorSetBlockIoThrottle(priv->mon, device,
>                                              &info, supportMaxOptions,
> -                                            supportGroupNameOption,
> +                                            set_fields & QEMU_BLOCK_IOTUNE_SET_GROUP_NAME,
>                                              supportMaxLengthOptions);
>          if (qemuDomainObjExitMonitor(driver, vm) < 0)
>              ret = -1;
> 

I believe this should be a change to qemuMonitorJSONSetBlockIoThrottle
to use 'S' instead of 's' in the virJSONValueObjectAdd call.

Been too long to remember why I went with 's' - although I wonder if it
had to do with "unsetting" the value... I do believe I should have gone
with my first instincts on this and should have made the design around
allowing the user to define a group number to use and then convert that
into a group name string with a static prefix and the number <sigh>.

ACK with that change.

John