blk-wbt: fix that wbt can't be disabled by default

commit b11d31ae01e6 ("blk-wbt: remove unnecessary check in
wbt_enable_default()") removes the checking of CONFIG_BLK_WBT_MQ by
mistake, which is used to control enable or disable wbt by default.

Fix the problem by adding back the checking. This patch also do a litter
cleanup to make related code more readable.

Fixes: b11d31ae01e6 ("blk-wbt: remove unnecessary check in wbt_enable_default()")
Reported-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/lkml/CAKXUXMzfKq_J9nKHGyr5P5rvUETY4B-fxoQD4sO+NYjFOfVtZA@mail.gmail.com/t/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230522121854.2928880-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index e49a486..9ec2a2f 100644 (file)
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -730,14 +730,16 @@ void wbt_enable_default(struct gendisk *disk)
 {
        struct request_queue *q = disk->queue;
        struct rq_qos *rqos;
-       bool disable_flag = q->elevator &&
-                   test_bit(ELEVATOR_FLAG_DISABLE_WBT, &q->elevator->flags);
+       bool enable = IS_ENABLED(CONFIG_BLK_WBT_MQ);
+
+       if (q->elevator &&
+           test_bit(ELEVATOR_FLAG_DISABLE_WBT, &q->elevator->flags))
+               enable = false;
 
        /* Throttling already enabled? */
        rqos = wbt_rq_qos(q);
        if (rqos) {
-               if (!disable_flag &&
-                   RQWB(rqos)->enable_state == WBT_STATE_OFF_DEFAULT)
+               if (enable && RQWB(rqos)->enable_state == WBT_STATE_OFF_DEFAULT)
                        RQWB(rqos)->enable_state = WBT_STATE_ON_DEFAULT;
                return;
        }
@@ -746,7 +748,7 @@ void wbt_enable_default(struct gendisk *disk)
        if (!blk_queue_registered(q))
                return;
 
-       if (queue_is_mq(q) && !disable_flag)
+       if (queue_is_mq(q) && enable)
                wbt_init(disk);
 }
 EXPORT_SYMBOL_GPL(wbt_enable_default);