blk-wbt: make sure throttle is enabled properly

BugLink: https://bugs.launchpad.net/bugs/1938340
[ 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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 3aaeefe393c8c80850815b0d29f0a10a4c04ddef..4ec0a018a2ad3ffa5081a26ac98ca2b969d9992d 100644 (file)
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -637,9 +637,13 @@ 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))