Commit c9589f03 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe

blk-throttle: improve queue bypass handling

If a queue is bypassing, all blkcg policies should become noops but
blk-throttle wasn't.  It only became noop if the queue was dying.
While this wouldn't lead to an oops as falling back to the root blkg
is safe in this case, this can be a bit surprising - a bypassing queue
could still be applying throttle limits.

Fix it by removing blk_queue_dying() test in throtl_lookup_create_tg()
and testing blk_queue_bypass() in blk_throtl_bio() and bypassing
before doing anything else.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 85b6bc9d
...@@ -475,7 +475,7 @@ static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td, ...@@ -475,7 +475,7 @@ static struct throtl_grp *throtl_lookup_create_tg(struct throtl_data *td,
/* if %NULL and @q is alive, fall back to root_tg */ /* if %NULL and @q is alive, fall back to root_tg */
if (!IS_ERR(blkg)) if (!IS_ERR(blkg))
tg = blkg_to_tg(blkg); tg = blkg_to_tg(blkg);
else if (!blk_queue_dying(q)) else
tg = td_root_tg(td); tg = td_root_tg(td);
} }
...@@ -1438,10 +1438,11 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio) ...@@ -1438,10 +1438,11 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
* IO group * IO group
*/ */
spin_lock_irq(q->queue_lock); spin_lock_irq(q->queue_lock);
tg = throtl_lookup_create_tg(td, blkcg);
if (unlikely(!tg)) if (unlikely(blk_queue_bypass(q)))
goto out_unlock; goto out_unlock;
tg = throtl_lookup_create_tg(td, blkcg);
sq = &tg->service_queue; sq = &tg->service_queue;
while (true) { while (true) {
......
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