Merge pull request #19805 from vbotbuildovich/backport-pr-19794-v23.3…

….x-395

[v23.3.x] c/p_balancer: fixed possible overflow of final used ration

src/v/cluster/partition_balancer_types.h

@@ -45,6 +45,13 @@ struct node_disk_space {
     double peak_used_ratio() const { return double(used + assigned) / total; }
 
     double final_used_ratio() const {
+        // it sometimes may happen  that the partition replica size on one node
+        // is out of date with the total used size reported by a node space
+        // manager. This may lead to an overflow of final used ratio.
+        if (released >= used + assigned) {
+            return 0.0;
+        }
+
         return double(used + assigned - released) / total;
     }