blk-iocost: Reset vtime_base_rate in ioc_refresh_params

Since commit ac33e91e("blk-iocost: implement vtime loss compensation")
split vtime_rate into vtime_rate and vtime_base_rate, we need reset both
vtime_base_rate and vtime_rate when device parameters are refreshed.
If vtime_base_rate is no reset here, vtime_rate will be overwritten with
old vtime_base_rate soon in ioc_refresh_vrate.
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20221018121932.10792-3-shikemeng@huawei.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-iocost.c

@@ -906,8 +906,10 @@ static bool ioc_refresh_params(struct ioc *ioc, bool force)
 	if (idx == ioc->autop_idx && !force)
 		return false;
 
-	if (idx != ioc->autop_idx)
+	if (idx != ioc->autop_idx) {
 		atomic64_set(&ioc->vtime_rate, VTIME_PER_USEC);
+		ioc->vtime_base_rate = VTIME_PER_USEC;
+	}
 
 	ioc->autop_idx = idx;
 	ioc->autop_too_fast_at = 0;