blk-wbt: wake up all when we scale up, not down

josefbacik · axboe · commit 5e65a20341e0 · 2018-10-11T13:31:28.000-06:00
Tetsuo brought to my attention that I screwed up the scale_up/scale_down helpers when I factored out the rq-qos code. We need to wake up all the waiters when we add slots for requests to make, not when we shrink the slots. Otherwise we'll end up things waiting forever. This was a mistake and simply puts everything back the way it was. cc: stable@vger.kernel.org Fixes: a790504 ("blk-rq-qos: refactor out common elements of blk-wbt") eported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
@@ -310,6 +310,7 @@ static void scale_up(struct rq_wb *rwb)
 	rq_depth_scale_up(&rwb->rq_depth);
 	calc_wb_limits(rwb);
 	rwb->unknown_cnt = 0;
+	rwb_wake_all(rwb);
 	rwb_trace_step(rwb, "scale up");
 }
 
@@ -318,7 +319,6 @@ static void scale_down(struct rq_wb *rwb, bool hard_throttle)
 	rq_depth_scale_down(&rwb->rq_depth, hard_throttle);
 	calc_wb_limits(rwb);
 	rwb->unknown_cnt = 0;
-	rwb_wake_all(rwb);
 	rwb_trace_step(rwb, "scale down");
 }
 

Original file line number	Diff line number	Diff line change
`@@ -310,6 +310,7 @@ static void scale_up(struct rq_wb *rwb)`
`310`	`310`	`rq_depth_scale_up(&rwb->rq_depth);`
`311`	`311`	`calc_wb_limits(rwb);`
`312`	`312`	`rwb->unknown_cnt = 0;`
	`313`	`+ rwb_wake_all(rwb);`
`313`	`314`	`rwb_trace_step(rwb, "scale up");`
`314`	`315`	`}`
`315`	`316`
`@@ -318,7 +319,6 @@ static void scale_down(struct rq_wb *rwb, bool hard_throttle)`
`318`	`319`	`rq_depth_scale_down(&rwb->rq_depth, hard_throttle);`
`319`	`320`	`calc_wb_limits(rwb);`
`320`	`321`	`rwb->unknown_cnt = 0;`
`321`		`- rwb_wake_all(rwb);`
`322`	`322`	`rwb_trace_step(rwb, "scale down");`
`323`	`323`	`}`
`324`	`324`