On Thu 17 Sep 2015 03:48:17 PM CEST, Kevin Wolf wrote:
> +static void swap_feature_fields(BlockDriverState *bs_top,
> + BlockDriverState *bs_new)
> +{
> + BlockDriverState tmp;
> +
> + bdrv_move_feature_fields(&tmp, bs_top);
> + bdrv_move_feature_fields(bs_top, bs_new);
> + bdrv_move_feature_fields(bs_new, &tmp);
> +
> + assert(!bs_new->io_limits_enabled);
> + if (bs_top->io_limits_enabled) {
> + bdrv_io_limits_enable(bs_new, throttle_group_get_name(bs_top));
> + bdrv_io_limits_disable(bs_top);
> + }
> +}
I would use 'if (bs_top->throttle_state != NULL)' instead. That pointer
is set if and only if the BDS has I/O limits set.
bs->io_limits_enabled can be set to false in order to bypass the limits
temporarily without removing the BDS's throttling settings (e.g in
bdrv_read_unthrottled()).
I actually think that we can get rid of io_limits_enabled in several
places (if not completely), but I will take care of that in a separate
patch.
The only scenario that could cause problems is if bs->throttle_state is
set but bs->io_limits_enabled is false when swap_feature_fields() is
called, but I don't think that's possible in this case.
Berto
