crush: fix fast rule lookup when uniform

Older clients will search for the first rule with a matching ruleset, type, and size. The has_uniform_rules bool is only set if we have rule ids and rulesets that line up, but we must also verify that the rest of the mask matches or else we can get a different CRUSH mapping result because the mask might not match and old clients will fail to find a rule and we will find one. We also can't just check the ruleset as the legacy clients find the *first* (of potentially many) matching rules; hence we only do the fast check if all rulesets == rule id. Signed-off-by: Sage Weil <[email protected]>
heyingstar · Sep 6, 2017 · f24095e · f24095e
1 parent f0f93c6
commit f24095e
Showing 1 changed file with 8 additions and 7 deletions.
diff --git a/src/crush/CrushWrapper.h b/src/crush/CrushWrapper.h
@@ -1261,14 +1261,15 @@ class CrushWrapper {
 
   int find_rule(int ruleset, int type, int size) const {
     if (!crush) return -1;
-    if (!have_uniform_rules) {
-      return crush_find_rule(crush, ruleset, type, size);
-    } else {
-      if (ruleset < (int)crush->max_rules &&
-	  crush->rules[ruleset])
-	return ruleset;
-      return -1;
+    if (have_uniform_rules &&
+	ruleset < (int)crush->max_rules &&
+	crush->rules[ruleset] &&
+	crush->rules[ruleset]->mask.type == type &&
+	crush->rules[ruleset]->mask.min_size <= size &&
+	crush->rules[ruleset]->mask.max_size >= size) {
+      return ruleset;
     }
+    return crush_find_rule(crush, ruleset, type, size);
   }
 
   bool ruleset_exists(const int ruleset) const {