blk-throttle: factor out code to calculate ios/bytes_allowed

No functional changes, new apis will be used in later patches to
calculate wait time for throttled bios when new configuration is
submitted.

Noted this patch also rename tg_with_in_iops/bps_limit() to
tg_within_iops/bps_limit().

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220829022240.3348319-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 353bbd0886ca7a41bf9f82cd0091c0da89bd914a..89e76d52ee56c30a114eb937f0cdbba52fa2acdf 100644 (file)
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -754,33 +754,20 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)
                   tg->slice_start[rw], tg->slice_end[rw], jiffies);
 }
 
-static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,
-                                 u32 iops_limit, unsigned long *wait)
+static unsigned int calculate_io_allowed(u32 iops_limit,
+                                        unsigned long jiffy_elapsed)
 {
-       bool rw = bio_data_dir(bio);
        unsigned int io_allowed;
-       unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
        u64 tmp;
 
-       if (iops_limit == UINT_MAX) {
-               if (wait)
-                       *wait = 0;
-               return true;
-       }
-
-       jiffy_elapsed = jiffies - tg->slice_start[rw];
-
-       /* Round up to the next throttle slice, wait time must be nonzero */
-       jiffy_elapsed_rnd = roundup(jiffy_elapsed + 1, tg->td->throtl_slice);
-
        /*
-        * jiffy_elapsed_rnd should not be a big value as minimum iops can be
+        * jiffy_elapsed should not be a big value as minimum iops can be
         * 1 then at max jiffy elapsed should be equivalent of 1 second as we
         * will allow dispatch after 1 second and after that slice should
         * have been trimmed.
         */
 
-       tmp = (u64)iops_limit * jiffy_elapsed_rnd;
+       tmp = (u64)iops_limit * jiffy_elapsed;
        do_div(tmp, HZ);
 
        if (tmp > UINT_MAX)
@@ -788,6 +775,32 @@ static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,
        else
                io_allowed = tmp;
 
+       return io_allowed;
+}
+
+static u64 calculate_bytes_allowed(u64 bps_limit, unsigned long jiffy_elapsed)
+{
+       return mul_u64_u64_div_u64(bps_limit, (u64)jiffy_elapsed, (u64)HZ);
+}
+
+static bool tg_within_iops_limit(struct throtl_grp *tg, struct bio *bio,
+                                u32 iops_limit, unsigned long *wait)
+{
+       bool rw = bio_data_dir(bio);
+       unsigned int io_allowed;
+       unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;
+
+       if (iops_limit == UINT_MAX) {
+               if (wait)
+                       *wait = 0;
+               return true;
+       }
+
+       jiffy_elapsed = jiffies - tg->slice_start[rw];
+
+       /* Round up to the next throttle slice, wait time must be nonzero */
+       jiffy_elapsed_rnd = roundup(jiffy_elapsed + 1, tg->td->throtl_slice);
+       io_allowed = calculate_io_allowed(iops_limit, jiffy_elapsed_rnd);
        if (tg->io_disp[rw] + 1 <= io_allowed) {
                if (wait)
                        *wait = 0;
@@ -802,8 +815,8 @@ static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,
        return false;
 }
 
-static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
-                                u64 bps_limit, unsigned long *wait)
+static bool tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio,
+                               u64 bps_limit, unsigned long *wait)
 {
        bool rw = bio_data_dir(bio);
        u64 bytes_allowed, extra_bytes;
@@ -824,9 +837,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
                jiffy_elapsed_rnd = tg->td->throtl_slice;
 
        jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice);
-       bytes_allowed = mul_u64_u64_div_u64(bps_limit, (u64)jiffy_elapsed_rnd,
-                                           (u64)HZ);
-
+       bytes_allowed = calculate_bytes_allowed(bps_limit, jiffy_elapsed_rnd);
        if (tg->bytes_disp[rw] + bio_size <= bytes_allowed) {
                if (wait)
                        *wait = 0;
@@ -895,8 +906,8 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
                                jiffies + tg->td->throtl_slice);
        }
 
-       if (tg_with_in_bps_limit(tg, bio, bps_limit, &bps_wait) &&
-           tg_with_in_iops_limit(tg, bio, iops_limit, &iops_wait)) {
+       if (tg_within_bps_limit(tg, bio, bps_limit, &bps_wait) &&
+           tg_within_iops_limit(tg, bio, iops_limit, &iops_wait)) {
                if (wait)
                        *wait = 0;
                return true;