Patch "blk-wbt: fix that wbt can't be disabled by default" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     blk-wbt-fix-that-wbt-can-t-be-disabled-by-default.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 5376a7667a1f2430589c3b2f5f0bccafd1dd761b
Author: Yu Kuai <yukuai3@xxxxxxxxxx>
Date:   Mon May 22 20:18:54 2023 +0800

    blk-wbt: fix that wbt can't be disabled by default
    
    [ Upstream commit 8a2b20a997a3779ae9fcae268f2959eb82ec05a1 ]
    
    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@xxxxxxxxx>
    Link: https://lore.kernel.org/lkml/CAKXUXMzfKq_J9nKHGyr5P5rvUETY4B-fxoQD4sO+NYjFOfVtZA@xxxxxxxxxxxxxx/t/
    Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
    Reviewed-by: Christoph Hellwig <hch@xxxxxx>
    Link: https://lore.kernel.org/r/20230522121854.2928880-1-yukuai1@xxxxxxxxxxxxxxx
    Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index fcacdff8af93b..526fb12c3e4cf 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -640,14 +640,16 @@ 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;
 	}
@@ -656,7 +658,7 @@ 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);