[PATCH 2/4] block, bfq: reduce upper bound for inject limit to max_rq_in_driver+1

[Paolo Valente]

Upon an increment attempt of the injection limit, the latter is
constrained not to become higher than twice the maximum number
max_rq_in_driver of I/O requests that have happened to be in service
in the drive. This high bound allows the injection limit to grow
beyond max_rq_in_driver, which may then cause max_rq_in_driver itself
to grow.

However, since the limit is incremented by only one unit at a time,
there is no need for such a high bound, and just max_rq_in_driver+1 is
enough.

Signed-off-by: Paolo Valente <paolo.valente@xxxxxxxxxx>
---
 block/bfq-iosched.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 5a2bbd8613a8..e114282204f6 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -5805,7 +5805,7 @@ static void bfq_update_inject_limit(struct bfq_data *bfqd,
 			bfqq->inject_limit--;
 			bfqq->decrease_time_jif = jiffies;
 		} else if (tot_time_ns < threshold &&
-			   old_limit < bfqd->max_rq_in_driver<<1)
+			   old_limit <= bfqd->max_rq_in_driver)
 			bfqq->inject_limit++;
 	}
 
-- 
2.20.1