blk-wbt: allow wbt to be enabled always through sysfs

[mirror_ubuntu-bionic-kernel.git] / block / blk-sysfs.c

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index f0ca569e276b958518cbf6765547b9c99b861786..a9784149176902beab4b25223989c2d702819f40 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -425,20 +425,30 @@ static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
        ssize_t ret;
        s64 val;
 
-       rwb = q->rq_wb;
-       if (!rwb)
-               return -EINVAL;
-
        ret = queue_var_store64(&val, page);
        if (ret < 0)
                return ret;
+       if (val < -1)
+               return -EINVAL;
+
+       rwb = q->rq_wb;
+       if (!rwb) {
+               ret = wbt_init(q);
+               if (ret)
+                       return ret;
+
+               rwb = q->rq_wb;
+               if (!rwb)
+                       return -EINVAL;
+       }
 
        if (val == -1)
                rwb->min_lat_nsec = wbt_default_latency_nsec(q);
        else if (val >= 0)
                rwb->min_lat_nsec = val * 1000ULL;
-       else
-               return -EINVAL;
+
+       if (rwb->enable_state == WBT_STATE_ON_DEFAULT)
+               rwb->enable_state = WBT_STATE_ON_MANUAL;
 
        wbt_update_limits(rwb);
        return count;