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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, Zhang Yi <yi.zhang@huawei.com>,
        Jens Axboe <axboe@kernel.dk>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 178/348] blk-wbt: make sure throttle is enabled properly
Date:   Mon, 12 Jul 2021 08:09:22 +0200
Message-Id: <20210712060724.513089133@linuxfoundation.org>
In-Reply-To: <20210712060659.886176320@linuxfoundation.org>
References: <20210712060659.886176320@linuxfoundation.org>
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From: Zhang Yi <yi.zhang@huawei.com>

[ Upstream commit 76a8040817b4b9c69b53f9b326987fa891b4082a ]

After commit a79050434b45 ("blk-rq-qos: refactor out common elements of
blk-wbt"), if throttle was disabled by wbt_disable_default(), we could
not enable again, fix this by set enable_state back to
WBT_STATE_ON_DEFAULT.

Fixes: a79050434b45 ("blk-rq-qos: refactor out common elements of blk-wbt")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/r/20210619093700.920393-3-yi.zhang@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 block/blk-wbt.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 7c7dd5c14391..ee708c1bc352 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -645,9 +645,13 @@ void wbt_set_write_cache(struct request_queue *q, bool write_cache_on)
 void wbt_enable_default(struct request_queue *q)
 {
 	struct rq_qos *rqos = wbt_rq_qos(q);
+
 	/* Throttling already enabled? */
-	if (rqos)
+	if (rqos) {
+		if (RQWB(rqos)->enable_state == WBT_STATE_OFF_DEFAULT)
+			RQWB(rqos)->enable_state = WBT_STATE_ON_DEFAULT;
 		return;
+	}
 
 	/* Queue not registered? Maybe shutting down... */
 	if (!blk_queue_registered(q))
-- 
2.30.2