block: Replace struct rq_depth with unsigned int in struct iolatency_grp

We only need a max queue depth for every iolatency to limit the inflight io
number. Replace struct rq_depth with unsigned int to simplfy "struct
iolatency_grp" and save memory.
Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20221018111240.22612-4-shikemeng@huawei.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-iolatency.c

@@ -141,7 +141,7 @@ struct iolatency_grp {
 	struct latency_stat __percpu *stats;
 	struct latency_stat cur_stat;
 	struct blk_iolatency *blkiolat;
-	struct rq_depth rq_depth;
+	unsigned int max_depth;
 	struct rq_wait rq_wait;
 	atomic64_t window_start;
 	atomic_t scale_cookie;
@@ -280,7 +280,7 @@ static void iolat_cleanup_cb(struct rq_wait *rqw, void *private_data)
 static bool iolat_acquire_inflight(struct rq_wait *rqw, void *private_data)
 {
 	struct iolatency_grp *iolat = private_data;
-	return rq_wait_inc_below(rqw, iolat->rq_depth.max_depth);
+	return rq_wait_inc_below(rqw, iolat->max_depth);
 }
 
 static void __blkcg_iolatency_throttle(struct rq_qos *rqos,
@@ -374,7 +374,7 @@ static void scale_change(struct iolatency_grp *iolat, bool up)
 {
 	unsigned long qd = iolat->blkiolat->rqos.q->nr_requests;
 	unsigned long scale = scale_amount(qd, up);
-	unsigned long old = iolat->rq_depth.max_depth;
+	unsigned long old = iolat->max_depth;
 
 	if (old > qd)
 		old = qd;
@@ -386,12 +386,12 @@ static void scale_change(struct iolatency_grp *iolat, bool up)
 		if (old < qd) {
 			old += scale;
 			old = min(old, qd);
-			iolat->rq_depth.max_depth = old;
+			iolat->max_depth = old;
 			wake_up_all(&iolat->rq_wait.wait);
 		}
 	} else {
 		old >>= 1;
-		iolat->rq_depth.max_depth = max(old, 1UL);
+		iolat->max_depth = max(old, 1UL);
 	}
 }
 
@@ -444,7 +444,7 @@ static void check_scale_change(struct iolatency_grp *iolat)
 	}
 
 	/* We're as low as we can go. */
-	if (iolat->rq_depth.max_depth == 1 && direction < 0) {
+	if (iolat->max_depth == 1 && direction < 0) {
 		blkcg_use_delay(lat_to_blkg(iolat));
 		return;
 	}
@@ -452,7 +452,7 @@ static void check_scale_change(struct iolatency_grp *iolat)
 	/* We're back to the default cookie, unthrottle all the things. */
 	if (cur_cookie == DEFAULT_SCALE_COOKIE) {
 		blkcg_clear_delay(lat_to_blkg(iolat));
-		iolat->rq_depth.max_depth = UINT_MAX;
+		iolat->max_depth = UINT_MAX;
 		wake_up_all(&iolat->rq_wait.wait);
 		return;
 	}
@@ -507,7 +507,7 @@ static void iolatency_record_time(struct iolatency_grp *iolat,
 	 * We don't want to count issue_as_root bio's in the cgroups latency
 	 * statistics as it could skew the numbers downwards.
 	 */
-	if (unlikely(issue_as_root && iolat->rq_depth.max_depth != UINT_MAX)) {
+	if (unlikely(issue_as_root && iolat->max_depth != UINT_MAX)) {
 		u64 sub = iolat->min_lat_nsec;
 		if (req_time < sub)
 			blkcg_add_delay(lat_to_blkg(iolat), now, sub - req_time);
@@ -919,7 +919,7 @@ static void iolatency_ssd_stat(struct iolatency_grp *iolat, struct seq_file *s)
 	}
 	preempt_enable();
 
-	if (iolat->rq_depth.max_depth == UINT_MAX)
+	if (iolat->max_depth == UINT_MAX)
 		seq_printf(s, " missed=%llu total=%llu depth=max",
 			(unsigned long long)stat.ps.missed,
 			(unsigned long long)stat.ps.total);
@@ -927,7 +927,7 @@ static void iolatency_ssd_stat(struct iolatency_grp *iolat, struct seq_file *s)
 		seq_printf(s, " missed=%llu total=%llu depth=%u",
 			(unsigned long long)stat.ps.missed,
 			(unsigned long long)stat.ps.total,
-			iolat->rq_depth.max_depth);
+			iolat->max_depth);
 }
 
 static void iolatency_pd_stat(struct blkg_policy_data *pd, struct seq_file *s)
@@ -944,12 +944,12 @@ static void iolatency_pd_stat(struct blkg_policy_data *pd, struct seq_file *s)
 
 	avg_lat = div64_u64(iolat->lat_avg, NSEC_PER_USEC);
 	cur_win = div64_u64(iolat->cur_win_nsec, NSEC_PER_MSEC);
-	if (iolat->rq_depth.max_depth == UINT_MAX)
+	if (iolat->max_depth == UINT_MAX)
 		seq_printf(s, " depth=max avg_lat=%llu win=%llu",
 			avg_lat, cur_win);
 	else
 		seq_printf(s, " depth=%u avg_lat=%llu win=%llu",
-			iolat->rq_depth.max_depth, avg_lat, cur_win);
+			iolat->max_depth, avg_lat, cur_win);
 }
 
 static struct blkg_policy_data *iolatency_pd_alloc(gfp_t gfp,
@@ -993,9 +993,7 @@ static void iolatency_pd_init(struct blkg_policy_data *pd)
 	latency_stat_init(iolat, &iolat->cur_stat);
 	rq_wait_init(&iolat->rq_wait);
 	spin_lock_init(&iolat->child_lat.lock);
-	iolat->rq_depth.queue_depth = blkg->q->nr_requests;
-	iolat->rq_depth.max_depth = UINT_MAX;
-	iolat->rq_depth.default_depth = iolat->rq_depth.queue_depth;
+	iolat->max_depth = UINT_MAX;
 	iolat->blkiolat = blkiolat;
 	iolat->cur_win_nsec = 100 * NSEC_PER_MSEC;
 	atomic64_set(&iolat->window_start, now);