kvserver: guard inversion check and requeue behind PriorityInversionRequeue

Previously, we introduced the PriorityInversionRequeue cluster setting, intended
for backport, to handle cases where a range was enqueued with a high-priority
repair action but, at processing time, a low-priority rebalance action was
computed. In such cases, the caller re-adds the range to the queue under its
updated priority. Although the cluster setting guards this requeue behavior, the
inversion check always ran unconditionally, reducing backport safety. This
commit updates the logic so that the cluster setting guard both the inversion
check and the requeue behavior.

Author: wenyihu6

pkg/kv/kvserver/replicate_queue.go

@@ -926,21 +926,21 @@ func (rq *replicateQueue) processOneChange(
 	change, err := rq.planner.PlanOneChange(
 		ctx, repl, desc, conf, plan.PlannerOptions{Scatter: scatter})
 
-	inversion, shouldRequeue := allocatorimpl.CheckPriorityInversion(priorityAtEnqueue, change.Action)
-	if inversion {
-		if priorityInversionLogEveryN.ShouldLog() {
-			log.KvDistribution.Infof(ctx,
-				"priority inversion during process: shouldRequeue = %t action=%s, priority=%v, enqueuePriority=%v",
-				shouldRequeue, change.Action, change.Action.Priority(), priorityAtEnqueue)
-		}
-
-		if shouldRequeue && PriorityInversionRequeue.Get(&rq.store.cfg.Settings.SV) {
-			// Return true to requeue the range. Return the error to ensure it is
-			// logged and tracked in replicate queue bq.failures metrics. See
-			// replicateQueue.process for details.
-			return true /*requeue*/, maybeAnnotateDecommissionErr(
-				errors.Errorf("requing due to priority inversion: action=%s, priority=%v, enqueuePriority=%v",
-					change.Action, change.Action.Priority(), priorityAtEnqueue), change.Action)
+	if PriorityInversionRequeue.Get(&rq.store.cfg.Settings.SV) {
+		if inversion, shouldRequeue := allocatorimpl.CheckPriorityInversion(priorityAtEnqueue, change.Action); inversion {
+			if priorityInversionLogEveryN.ShouldLog() {
+				log.KvDistribution.Infof(ctx,
+					"priority inversion during process: shouldRequeue = %t action=%s, priority=%v, enqueuePriority=%v",
+					shouldRequeue, change.Action, change.Action.Priority(), priorityAtEnqueue)
+			}
+			if shouldRequeue {
+				// Return true to requeue the range. Return the error to ensure it is
+				// logged and tracked in replicate queue bq.failures metrics. See
+				// replicateQueue.process for details.
+				return true /*requeue*/, maybeAnnotateDecommissionErr(
+					errors.Errorf("requing due to priority inversion: action=%s, priority=%v, enqueuePriority=%v",
+						change.Action, change.Action.Priority(), priorityAtEnqueue), change.Action)
+			}
 		}
 	}