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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, kernel test robot <yujie.liu@intel.com>,
        Yu Kuai <yukuai3@huawei.com>, Ming Lei <ming.lei@redhat.com>,
        Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 5.15 519/530] blk-wbt: fix that rwb->wc is always set to 1 in wbt_init()
Date:   Mon, 24 Oct 2022 13:34:23 +0200
Message-Id: <20221024113108.503193211@linuxfoundation.org>
In-Reply-To: <20221024113044.976326639@linuxfoundation.org>
References: <20221024113044.976326639@linuxfoundation.org>
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From: Yu Kuai <yukuai3@huawei.com>

commit 285febabac4a16655372d23ff43e89ff6f216691 upstream.

commit 8c5035dfbb94 ("blk-wbt: call rq_qos_add() after wb_normal is
initialized") moves wbt_set_write_cache() before rq_qos_add(), which
is wrong because wbt_rq_qos() is still NULL.

Fix the problem by removing wbt_set_write_cache() and setting 'rwb->wc'
directly. Noted that this patch also remove the redundant setting of
'rab->wc'.

Fixes: 8c5035dfbb94 ("blk-wbt: call rq_qos_add() after wb_normal is initialized")
Reported-by: kernel test robot <yujie.liu@intel.com>
Link: https://lore.kernel.org/r/202210081045.77ddf59b-yujie.liu@intel.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20221009101038.1692875-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 block/blk-wbt.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -841,12 +841,11 @@ int wbt_init(struct request_queue *q)
 	rwb->last_comp = rwb->last_issue = jiffies;
 	rwb->win_nsec = RWB_WINDOW_NSEC;
 	rwb->enable_state = WBT_STATE_ON_DEFAULT;
-	rwb->wc = 1;
+	rwb->wc = test_bit(QUEUE_FLAG_WC, &q->queue_flags);
 	rwb->rq_depth.default_depth = RWB_DEF_DEPTH;
 	rwb->min_lat_nsec = wbt_default_latency_nsec(q);
 
 	wbt_queue_depth_changed(&rwb->rqos);
-	wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
 
 	/*
 	 * Assign rwb and add the stats callback.