On Fri 25 Aug 2017 03:23:30 PM CEST, Manos Pitsidianakis wrote:
> @@ -1957,12 +1957,18 @@ void blk_io_limits_enable(BlockBackend *blk, const
> char *group, Error **errp)
> BlockDriverState *bs = blk_bs(blk), *throttle_node;
> QDict *options = qdict_new();
> Error *local_err = NULL;
> - ThrottleState *ts;
> -
> - bdrv_drained_begin(bs);
>
> /* Force creation of group in case it doesn't exist */
> - ts = throttle_group_incref(group);
> + if (!throttle_group_exists(group)) {
> + throttle_group_new_legacy(group, &local_err);
> + if (local_err) {
> + error_propagate(errp, local_err);
> + return;
> + }
> + }
After this, the reference count of the new group is 2 (as is already
explained in throttle_group_new_legacy()).
> + bdrv_drained_begin(bs);
> +
> qdict_set_default_str(options, "file", bs->node_name);
> qdict_set_default_str(options, QEMU_OPT_THROTTLE_GROUP_NAME, group);
> throttle_node = bdrv_new_open_driver(bdrv_find_format("throttle"), NULL,
And the implicit throttle node will hold and extra reference, making it
3.
How do you delete the legacy throttle group then? block_set_io_throttle
with everything set to 0 disables I/O limits and destroys the node, but
the reference count is still 2 and the group is not destroyed.
> +static int query_throttle_groups_foreach(Object *obj, void *data)
> +{
> + ThrottleGroup *tg;
> + struct ThrottleGroupQuery *query = data;
> +
> + tg = (ThrottleGroup *)object_dynamic_cast(obj, TYPE_THROTTLE_GROUP);
> + if (!tg) {
> + return 0;
> + }
> +
> + if (!g_strcmp0(query->name, tg->name)) {
> + query->result = tg;
> + return 1;
> + }
> +
> + return 0;
> +}
If you want you can make this a bit shorter if you merge both ifs:
if (tg && !g_strcmp0(query->name, tg->name)) {
query->result = tg;
return 1;
}
return 0;
> +void throttle_group_new_legacy(const char *name, Error **errp)
> +{
> + ThrottleGroup *tg = NULL;
No need to initialize tg here.
> ThrottleState *throttle_group_incref(const char *name)
> {
I think that you can make this one static and remove it from
throttle-groups.h (no one else is using it). Same with
throttle_group_unref.
Berto
