From: xie xingguo <xie.xingguo@zte.com.cn>
Date: Tue, 27 Jun 2017 12:24:59 +0000 (+0800)
Subject: crush: fix potential class id collision
X-Git-Tag: v12.1.1~42^2~4
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=906f0b5bcda450a95f20648c2312139aca5491d4;p=ceph.git

crush: fix potential class id collision

Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>
---

diff --git a/src/crush/CrushWrapper.cc b/src/crush/CrushWrapper.cc
index 012a065fbdc..15ce05139bc 100644
--- a/src/crush/CrushWrapper.cc
+++ b/src/crush/CrushWrapper.cc
@@ -1283,6 +1283,31 @@ int CrushWrapper::trim_roots_with_class(bool unused)
   return 0;
 }
 
+int32_t CrushWrapper::_alloc_class_id() const {
+  if (class_name.empty()) {
+    return 0;
+  }
+  int32_t class_id = class_name.rbegin()->first + 1;
+  if (class_id >= 0) {
+    return class_id;
+  }
+  // wrapped, pick a random start and do exhaustive search
+  uint32_t upperlimit = numeric_limits<int32_t>::max() + 1;
+  class_id = rand() % upperlimit;
+  const auto start = class_id;
+  do {
+    if (!class_name.count(class_id)) {
+      return class_id;
+    } else {
+      class_id++;
+      if (class_id < 0) {
+        class_id = 0;
+      }
+    }
+  } while (class_id != start);
+  assert(0 == "no available class id");
+}
+
 void CrushWrapper::reweight(CephContext *cct)
 {
   set<int> roots;
diff --git a/src/crush/CrushWrapper.h b/src/crush/CrushWrapper.h
index 56b26dbd075..5e3a8ea6da6 100644
--- a/src/crush/CrushWrapper.h
+++ b/src/crush/CrushWrapper.h
@@ -482,10 +482,12 @@ public:
     return 0;
   }
 
+  int32_t _alloc_class_id() const;
+
   int get_or_create_class_id(const string& name) {
     int c = get_class_id(name);
     if (c < 0) {
-      int i = class_name.size();
+      int i = _alloc_class_id();
       class_name[i] = name;
       class_rname[name] = i;
       return i;