blk-throttle: don't take carryover for prioritized processing of metadata

Commit 29390bb5661d ("blk-throttle: support prioritized processing of metadata")
takes bytes/ios carryover for prioritized processing of metadata. Turns out
we can support it by charging it directly without trimming slice, and the
result is same with carryover.

Cc: Tejun Heo <tj@kernel.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20250305043123.3938491-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 213e7b04617a00b165a878c7716b953f456b159b..7271aee94faf961676b318d35bf4751285a3e5fb 100644 (file)
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1620,13 +1620,6 @@ static bool tg_within_limit(struct throtl_grp *tg, struct bio *bio, bool rw)
        return tg_may_dispatch(tg, bio, NULL);
 }
 
-static void tg_dispatch_in_debt(struct throtl_grp *tg, struct bio *bio, bool rw)
-{
-       if (!bio_flagged(bio, BIO_BPS_THROTTLED))
-               tg->carryover_bytes[rw] -= throtl_bio_data_size(bio);
-       tg->carryover_ios[rw]--;
-}
-
 bool __blk_throtl_bio(struct bio *bio)
 {
        struct request_queue *q = bdev_get_queue(bio->bi_bdev);
@@ -1663,10 +1656,12 @@ bool __blk_throtl_bio(struct bio *bio)
                        /*
                         * IOs which may cause priority inversions are
                         * dispatched directly, even if they're over limit.
-                        * Debts are handled by carryover_bytes/ios while
-                        * calculating wait time.
+                        *
+                        * Charge and dispatch directly, and our throttle
+                        * control algorithm is adaptive, and extra IO bytes
+                        * will be throttled for paying the debt
                         */
-                       tg_dispatch_in_debt(tg, bio, rw);
+                       throtl_charge_bio(tg, bio);
                } else {
                        /* if above limits, break to queue */
                        break;