[PATCH] block, bfq: Init saved_wr_start_at_switch_to_srt in unlikely case

From: Douglas Anderson
Date: Wed Jun 26 2019 - 16:00:36 EST

Some debug code suggested by Paolo was tripping when I did reboot
stress tests. Specifically in bfq_bfqq_resume_state()
"bic->saved_wr_start_at_switch_to_srt" was later than the current
value of "jiffies". A bit of debugging showed that
"bic->saved_wr_start_at_switch_to_srt" was actually 0 and a bit more
debugging showed that was because we had run through the "unlikely"
case in the bfq_bfqq_save_state() function.

Let's init "saved_wr_start_at_switch_to_srt" in the unlikely case to
something sane.

NOTE: this fixes no known real-world errors.

Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Reviewed-by: Paolo Valente <paolo.valente@xxxxxxxxxx>
Paolo said to add his Reviewed-by in https://crrev.com/c/1678756.

block/bfq-iosched.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 72840ebf953e..008c93d6b8d7 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2678,6 +2678,7 @@ static void bfq_bfqq_save_state(struct bfq_queue *bfqq)
* to enjoy weight raising if split soon.
bic->saved_wr_coeff = bfqq->bfqd->bfq_wr_coeff;
+ bic->saved_wr_start_at_switch_to_srt = bfq_smallest_from_now();
bic->saved_wr_cur_max_time = bfq_wr_duration(bfqq->bfqd);
bic->saved_last_wr_start_finish = jiffies;
} else {