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 <sage@redhat.com>
(cherry picked from commit f24095e0e9734531dbdbcd4bff1392c463188e8e)

diff --git a/src/crush/CrushWrapper.h b/src/crush/CrushWrapper.h
index 3737d57300230404dd6b086861a2d10fd28c5941..384af2c442692357969c9d483b27b5f821b3b2f2 100644 (file)
--- a/src/crush/CrushWrapper.h
+++ b/src/crush/CrushWrapper.h
@@ -1258,14 +1258,15 @@ public:
 
   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 {