Merge pull request #23941 from trociny/wip-23445

librbd: flatten operation should use object map

Reviewed-by: Jason Dillaman <dillaman@redhat.com>

src/librbd/ObjectMap.cc

@@ -110,6 +110,32 @@ bool ObjectMap<I>::object_may_exist(uint64_t object_no) const
   return exists;
 }
 
+template <typename I>
+bool ObjectMap<I>::object_may_not_exist(uint64_t object_no) const
+{
+  ceph_assert(m_image_ctx.snap_lock.is_locked());
+
+  // Fall back to default logic if object map is disabled or invalid
+  if (!m_image_ctx.test_features(RBD_FEATURE_OBJECT_MAP,
+                                 m_image_ctx.snap_lock)) {
+    return true;
+  }
+
+  bool flags_set;
+  int r = m_image_ctx.test_flags(RBD_FLAG_OBJECT_MAP_INVALID,
+                                 m_image_ctx.snap_lock, &flags_set);
+  if (r < 0 || flags_set) {
+    return true;
+  }
+
+  RWLock::RLocker l(m_image_ctx.object_map_lock);
+  uint8_t state = (*this)[object_no];
+  bool nonexistent = (state != OBJECT_EXISTS && state != OBJECT_EXISTS_CLEAN);
+  ldout(m_image_ctx.cct, 20) << "object_no=" << object_no << " r="
+                             << nonexistent << dendl;
+  return nonexistent;
+}
+
 template <typename I>
 bool ObjectMap<I>::update_required(const ceph::BitVector<2>::Iterator& it,
                                    uint8_t new_state) {

src/librbd/ObjectMap.h

@@ -48,6 +48,7 @@ public:
   void close(Context *on_finish);
   bool set_object_map(ceph::BitVector<2> &target_object_map);
   bool object_may_exist(uint64_t object_no) const;
+  bool object_may_not_exist(uint64_t object_no) const;
 
   void aio_save(Context *on_finish);
   void aio_resize(uint64_t new_size, uint8_t default_object_state,

src/librbd/operation/FlattenRequest.cc

@@ -40,6 +40,15 @@ public:
       return -ERESTART;
     }
 
+    {
+      RWLock::RLocker snap_lock(image_ctx.snap_lock);
+      if (image_ctx.object_map != nullptr &&
+          !image_ctx.object_map->object_may_not_exist(m_object_no)) {
+        // can skip because the object already exists
+        return 1;
+      }
+    }
+
     bufferlist bl;
     string oid = image_ctx.get_object_name(m_object_no);
     auto req = new io::ObjectWriteRequest<I>(&image_ctx, oid, m_object_no, 0,