blk-throttle: remove THROTL_TG_HAS_IOPS_LIMIT

Currently, "tg->has_rules" and "tg->flags & THROTL_TG_HAS_IOPS_LIMIT"
both try to bypass bios that don't need to be throttled, however, they are
a little redundant and both not perfect:

1) "tg->has_rules" only distinguish read and write, but not iops and bps
   limit.
2) "tg->flags & THROTL_TG_HAS_IOPS_LIMIT" only check if iops limit
   exist, read and write is not distinguished, and bps limit is not
   checked.

tg->has_rules will extended to distinguish bps and iops in the following
patch. There is no need to keep the flag.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220921095309.1481289-2-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 55f2d98..a062539 100644 (file)
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -420,24 +420,12 @@ static void tg_update_has_rules(struct throtl_grp *tg)
        struct throtl_grp *parent_tg = sq_to_tg(tg->service_queue.parent_sq);
        struct throtl_data *td = tg->td;
        int rw;
-       int has_iops_limit = 0;
-
-       for (rw = READ; rw <= WRITE; rw++) {
-               unsigned int iops_limit = tg_iops_limit(tg, rw);
 
+       for (rw = READ; rw <= WRITE; rw++)
                tg->has_rules[rw] = (parent_tg && parent_tg->has_rules[rw]) ||
                        (td->limit_valid[td->limit_index] &&
                         (tg_bps_limit(tg, rw) != U64_MAX ||
-                         iops_limit != UINT_MAX));
-
-               if (iops_limit != UINT_MAX)
-                       has_iops_limit = 1;
-       }
-
-       if (has_iops_limit)
-               tg->flags |= THROTL_TG_HAS_IOPS_LIMIT;
-       else
-               tg->flags &= ~THROTL_TG_HAS_IOPS_LIMIT;
+                         tg_iops_limit(tg, rw) != UINT_MAX));
 }
 
 static void throtl_pd_online(struct blkg_policy_data *pd)

diff --git a/block/blk-throttle.h b/block/blk-throttle.h
index 66b4292..3994b89 100644 (file)
--- a/block/blk-throttle.h
+++ b/block/blk-throttle.h
@@ -55,8 +55,7 @@ struct throtl_service_queue {
 enum tg_state_flags {
        THROTL_TG_PENDING       = 1 << 0,       /* on parent's pending tree */
        THROTL_TG_WAS_EMPTY     = 1 << 1,       /* bio_lists[] became non-empty */
-       THROTL_TG_HAS_IOPS_LIMIT = 1 << 2,      /* tg has iops limit */
-       THROTL_TG_CANCELING     = 1 << 3,       /* starts to cancel bio */
+       THROTL_TG_CANCELING     = 1 << 2,       /* starts to cancel bio */
 };
 
 enum {
@@ -183,11 +182,6 @@ static inline bool blk_throtl_bio(struct bio *bio)
 {
        struct throtl_grp *tg = blkg_to_tg(bio->bi_blkg);
 
-       /* no need to throttle bps any more if the bio has been throttled */
-       if (bio_flagged(bio, BIO_BPS_THROTTLED) &&
-           !(tg->flags & THROTL_TG_HAS_IOPS_LIMIT))
-               return false;
-
        if (!tg->has_rules[bio_data_dir(bio)])
                return false;