IDMAnagement: Add owner ID pointer to embedded ones.

Add a dedicated `owner_id` pointer to ID types that can be embedded
(Collections and NodeTrees), and modify slightly come code to make
handling those more safe and consistent.

This implements first part of T69169.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D15838

20 files changed, 118 insertions, 89 deletions

diff --git a/source/blender/blenkernel/BKE_collection.h b/source/blender/blenkernel/BKE_collection.h
index feb3dc7de80..4a729311b6a 100644
--- a/source/blender/blenkernel/BKE_collection.h
+++ b/source/blender/blenkernel/BKE_collection.h
@@ -94,7 +94,7 @@ struct Collection *BKE_collection_duplicate(struct Main *bmain,
 /* Master Collection for Scene */
 
 #define BKE_SCENE_COLLECTION_NAME "Scene Collection"
-struct Collection *BKE_collection_master_add(void);
+struct Collection *BKE_collection_master_add(struct Scene *scene);
 
 /* Collection Objects */
 
@@ -296,7 +296,9 @@ void BKE_main_collections_parent_relations_rebuild(struct Main *bmain);
 /* .blend file I/O */
 
 void BKE_collection_blend_write_nolib(struct BlendWriter *writer, struct Collection *collection);
-void BKE_collection_blend_read_data(struct BlendDataReader *reader, struct Collection *collection);
+void BKE_collection_blend_read_data(struct BlendDataReader *reader,
+                                    struct Collection *collection,
+                                    struct ID *owner_id);
 void BKE_collection_blend_read_lib(struct BlendLibReader *reader, struct Collection *collection);
 void BKE_collection_blend_read_expand(struct BlendExpander *expander,
                                       struct Collection *collection);
diff --git a/source/blender/blenkernel/BKE_node.h b/source/blender/blenkernel/BKE_node.h
index 8affbf0ca67..46303a4e19c 100644
--- a/source/blender/blenkernel/BKE_node.h
+++ b/source/blender/blenkernel/BKE_node.h
@@ -472,6 +472,11 @@ void ntreeSetTypes(const struct bContext *C, struct bNodeTree *ntree);
 
 struct bNodeTree *ntreeAddTree(struct Main *bmain, const char *name, const char *idname);
 
+struct bNodeTree *ntreeAddTreeEmbedded(struct Main *bmain,
+                                       struct ID *owner_id,
+                                       const char *name,
+                                       const char *idname);
+
 /* copy/free funcs, need to manage ID users */
 
 /**
@@ -540,7 +545,9 @@ void ntreeBlendWrite(struct BlendWriter *writer, struct bNodeTree *ntree);
 /**
  * \note `ntree` itself has been read!
  */
-void ntreeBlendReadData(struct BlendDataReader *reader, struct bNodeTree *ntree);
+void ntreeBlendReadData(struct BlendDataReader *reader,
+                        struct ID *owner_id,
+                        struct bNodeTree *ntree);
 void ntreeBlendReadLib(struct BlendLibReader *reader, struct bNodeTree *ntree);
 void ntreeBlendReadExpand(struct BlendExpander *expander, struct bNodeTree *ntree);
 
diff --git a/source/blender/blenkernel/intern/collection.c b/source/blender/blenkernel/intern/collection.c
index caf59a9b363..572a0caa3c7 100644
--- a/source/blender/blenkernel/intern/collection.c
+++ b/source/blender/blenkernel/intern/collection.c
@@ -143,6 +143,9 @@ static void collection_foreach_id(ID *id, LibraryForeachIDData *data)
 {
   Collection *collection = (Collection *)id;
 
+  BKE_LIB_FOREACHID_PROCESS_ID(
+      data, collection->owner_id, IDWALK_CB_LOOPBACK | IDWALK_CB_NEVER_SELF);
+
   LISTBASE_FOREACH (CollectionObject *, cob, &collection->gobject) {
     BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, cob->ob, IDWALK_CB_USER);
   }
@@ -162,7 +165,7 @@ static void collection_foreach_id(ID *id, LibraryForeachIDData *data)
   }
 }
 
-static ID *collection_owner_get(Main *bmain, ID *id, ID *owner_id_hint)
+static ID *collection_owner_get(Main *bmain, ID *id, ID *UNUSED(owner_id_hint))
 {
   if ((id->flag & LIB_EMBEDDED_DATA) == 0) {
     return id;
@@ -171,20 +174,21 @@ static ID *collection_owner_get(Main *bmain, ID *id, ID *owner_id_hint)
 
   Collection *master_collection = (Collection *)id;
   BLI_assert((master_collection->flag & COLLECTION_IS_MASTER) != 0);
+  BLI_assert(master_collection->owner_id != NULL);
 
-  if (owner_id_hint != NULL && GS(owner_id_hint->name) == ID_SCE &&
-      ((Scene *)owner_id_hint)->master_collection == master_collection) {
-    return owner_id_hint;
-  }
-
+#ifndef NDEBUG
+  bool is_owner_found = false;
   LISTBASE_FOREACH (Scene *, scene, &bmain->scenes) {
     if (scene->master_collection == master_collection) {
-      return &scene->id;
+      BLI_assert(master_collection->owner_id == &scene->id);
+      BLI_assert(!is_owner_found);
+      is_owner_found = true;
     }
   }
+  BLI_assert(is_owner_found);
+#endif
 
-  BLI_assert_msg(0, "Embedded collection with no owner. Critical Main inconsistency.");
-  return NULL;
+  return master_collection->owner_id;
 }
 
 void BKE_collection_blend_write_nolib(BlendWriter *writer, Collection *collection)
@@ -233,8 +237,13 @@ void BKE_collection_compat_blend_read_data(BlendDataReader *reader, SceneCollect
 }
 #endif
 
-void BKE_collection_blend_read_data(BlendDataReader *reader, Collection *collection)
+void BKE_collection_blend_read_data(BlendDataReader *reader, Collection *collection, ID *owner_id)
 {
+  /* Special case for this pointer, do not rely on regular `lib_link` process here. Avoids needs
+   * for do_versioning, and ensures coherence of data in any case. */
+  BLI_assert((collection->id.flag & LIB_EMBEDDED_DATA) != 0 || owner_id == NULL);
+  collection->owner_id = owner_id;
+
   BLO_read_list(reader, &collection->gobject);
   BLO_read_list(reader, &collection->children);
 
@@ -265,7 +274,7 @@ void BKE_collection_blend_read_data(BlendDataReader *reader, Collection *collect
 static void collection_blend_read_data(BlendDataReader *reader, ID *id)
 {
   Collection *collection = (Collection *)id;
-  BKE_collection_blend_read_data(reader, collection);
+  BKE_collection_blend_read_data(reader, collection, NULL);
 }
 
 static void lib_link_collection_data(BlendLibReader *reader, Library *lib, Collection *collection)
@@ -849,14 +858,18 @@ Base *BKE_collection_or_layer_objects(const ViewLayer *view_layer, Collection *c
 /** \name Scene Master Collection
  * \{ */
 
-Collection *BKE_collection_master_add()
+Collection *BKE_collection_master_add(Scene *scene)
 {
+  BLI_assert(scene != NULL && scene->master_collection == NULL);
+
   /* Not an actual datablock, but owned by scene. */
   Collection *master_collection = BKE_libblock_alloc(
       NULL, ID_GR, BKE_SCENE_COLLECTION_NAME, LIB_ID_CREATE_NO_MAIN);
   master_collection->id.flag |= LIB_EMBEDDED_DATA;
+  master_collection->owner_id = &scene->id;
   master_collection->flag |= COLLECTION_IS_MASTER;
   master_collection->color_tag = COLLECTION_COLOR_NONE;
+
   return master_collection;
 }
 
diff --git a/source/blender/blenkernel/intern/linestyle.c b/source/blender/blenkernel/intern/linestyle.c
index 12a661d139b..776fe06edf7 100644
--- a/source/blender/blenkernel/intern/linestyle.c
+++ b/source/blender/blenkernel/intern/linestyle.c
@@ -2041,9 +2041,7 @@ void BKE_linestyle_default_shader(const bContext *C, FreestyleLineStyle *linesty
 
   BLI_assert(linestyle->nodetree == NULL);
 
-  ntree = ntreeAddTree(NULL, "stroke_shader", "ShaderNodeTree");
-
-  linestyle->nodetree = ntree;
+  ntree = ntreeAddTreeEmbedded(NULL, &linestyle->id, "stroke_shader", "ShaderNodeTree");
 
   uv_along_stroke = nodeAddStaticNode(C, ntree, SH_NODE_UVALONGSTROKE);
   uv_along_stroke->locx = 0.0f;
diff --git a/source/blender/blenkernel/intern/material.c b/source/blender/blenkernel/intern/material.c
index 248d292664a..442b31ff21e 100644
--- a/source/blender/blenkernel/intern/material.c
+++ b/source/blender/blenkernel/intern/material.c
@@ -1962,8 +1962,8 @@ static void material_default_surface_init(Material *ma)
 {
   strcpy(ma->id.name, "MADefault Surface");
 
-  bNodeTree *ntree = ntreeAddTree(NULL, "Shader Nodetree", ntreeType_Shader->idname);
-  ma->nodetree = ntree;
+  bNodeTree *ntree = ntreeAddTreeEmbedded(
+      NULL, &ma->id, "Shader Nodetree", ntreeType_Shader->idname);
   ma->use_nodes = true;
 
   bNode *principled = nodeAddStaticNode(NULL, ntree, SH_NODE_BSDF_PRINCIPLED);
@@ -1990,8 +1990,8 @@ static void material_default_volume_init(Material *ma)
 {
   strcpy(ma->id.name, "MADefault Volume");
 
-  bNodeTree *ntree = ntreeAddTree(NULL, "Shader Nodetree", ntreeType_Shader->idname);
-  ma->nodetree = ntree;
+  bNodeTree *ntree = ntreeAddTreeEmbedded(
+      NULL, &ma->id, "Shader Nodetree", ntreeType_Shader->idname);
   ma->use_nodes = true;
 
   bNode *principled = nodeAddStaticNode(NULL, ntree, SH_NODE_VOLUME_PRINCIPLED);
@@ -2015,8 +2015,8 @@ static void material_default_holdout_init(Material *ma)
 {
   strcpy(ma->id.name, "MADefault Holdout");
 
-  bNodeTree *ntree = ntreeAddTree(NULL, "Shader Nodetree", ntreeType_Shader->idname);
-  ma->nodetree = ntree;
+  bNodeTree *ntree = ntreeAddTreeEmbedded(
+      NULL, &ma->id, "Shader Nodetree", ntreeType_Shader->idname);
   ma->use_nodes = true;
 
   bNode *holdout = nodeAddStaticNode(NULL, ntree, SH_NODE_HOLDOUT);
diff --git a/source/blender/blenkernel/intern/node.cc b/source/blender/blenkernel/intern/node.cc
index e1eaed71f37..3cb2b80813f 100644
--- a/source/blender/blenkernel/intern/node.cc
+++ b/source/blender/blenkernel/intern/node.cc
@@ -325,6 +325,8 @@ static void node_foreach_id(ID *id, LibraryForeachIDData *data)
 {
   bNodeTree *ntree = (bNodeTree *)id;
 
+  BKE_LIB_FOREACHID_PROCESS_ID(data, ntree->owner_id, IDWALK_CB_LOOPBACK);
+
   BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, ntree->gpd, IDWALK_CB_USER);
 
   LISTBASE_FOREACH (bNode *, node, &ntree->nodes) {
@@ -399,7 +401,7 @@ static void node_foreach_path(ID *id, BPathForeachPathData *bpath_data)
   }
 }
 
-static ID *node_owner_get(Main *bmain, ID *id, ID *owner_id_hint)
+static ID *node_owner_get(Main *UNUSED(bmain), ID *id, ID *UNUSED(owner_id_hint))
 {
   if ((id->flag & LIB_EMBEDDED_DATA) == 0) {
     return id;
@@ -408,30 +410,10 @@ static ID *node_owner_get(Main *bmain, ID *id, ID *owner_id_hint)
   // BLI_assert((id->tag & LIB_TAG_NO_MAIN) == 0);
 
   bNodeTree *ntree = reinterpret_cast<bNodeTree *>(id);
+  BLI_assert(ntree->owner_id != NULL);
+  BLI_assert(ntreeFromID(ntree->owner_id) == ntree);
 
-  if (owner_id_hint != nullptr && ntreeFromID(owner_id_hint) == ntree) {
-    return owner_id_hint;
-  }
-
-  ListBase *lists[] = {&bmain->materials,
-                       &bmain->lights,
-                       &bmain->worlds,
-                       &bmain->textures,
-                       &bmain->scenes,
-                       &bmain->linestyles,
-                       &bmain->simulations,
-                       nullptr};
-
-  for (int i = 0; lists[i] != nullptr; i++) {
-    LISTBASE_FOREACH (ID *, id_iter, lists[i]) {
-      if (ntreeFromID(id_iter) == ntree) {
-        return id_iter;
-      }
-    }
-  }
-
-  BLI_assert_msg(0, "Embedded node tree with no owner. Critical Main inconsistency.");
-  return nullptr;
+  return ntree->owner_id;
 }
 
 static void write_node_socket_default_value(BlendWriter *writer, bNodeSocket *sock)
@@ -667,8 +649,13 @@ static void direct_link_node_socket(BlendDataReader *reader, bNodeSocket *sock)
   sock->runtime = MEM_new<bNodeSocketRuntime>(__func__);
 }
 
-void ntreeBlendReadData(BlendDataReader *reader, bNodeTree *ntree)
+void ntreeBlendReadData(BlendDataReader *reader, ID *owner_id, bNodeTree *ntree)
 {
+  /* Special case for this pointer, do not rely on regular `lib_link` process here. Avoids needs
+   * for do_versioning, and ensures coherence of data in any case. */
+  BLI_assert((ntree->id.flag & LIB_EMBEDDED_DATA) != 0 || owner_id == nullptr);
+  ntree->owner_id = owner_id;
+
   /* NOTE: writing and reading goes in sync, for speed. */
   ntree->is_updating = false;
   ntree->typeinfo = nullptr;
@@ -830,7 +817,7 @@ void ntreeBlendReadData(BlendDataReader *reader, bNodeTree *ntree)
 static void ntree_blend_read_data(BlendDataReader *reader, ID *id)
 {
   bNodeTree *ntree = (bNodeTree *)id;
-  ntreeBlendReadData(reader, ntree);
+  ntreeBlendReadData(reader, nullptr, ntree);
 }
 
 static void lib_link_node_socket(BlendLibReader *reader, Library *lib, bNodeSocket *sock)
@@ -2575,12 +2562,12 @@ void nodePositionPropagate(bNode *node)
   }
 }
 
-bNodeTree *ntreeAddTree(Main *bmain, const char *name, const char *idname)
+static bNodeTree *ntreeAddTree_do(
+    Main *bmain, ID *owner_id, const bool is_embedded, const char *name, const char *idname)
 {
   /* trees are created as local trees for compositor, material or texture nodes,
    * node groups and other tree types are created as library data.
    */
-  const bool is_embedded = (bmain == nullptr);
   int flag = 0;
   if (is_embedded) {
     flag |= LIB_ID_CREATE_NO_MAIN;
@@ -2588,7 +2575,15 @@ bNodeTree *ntreeAddTree(Main *bmain, const char *name, const char *idname)
   bNodeTree *ntree = (bNodeTree *)BKE_libblock_alloc(bmain, ID_NT, name, flag);
   BKE_libblock_init_empty(&ntree->id);
   if (is_embedded) {
+    BLI_assert(owner_id != NULL);
     ntree->id.flag |= LIB_EMBEDDED_DATA;
+    ntree->owner_id = owner_id;
+    bNodeTree **ntree_owner_ptr = BKE_ntree_ptr_from_id(owner_id);
+    BLI_assert(ntree_owner_ptr != NULL);
+    *ntree_owner_ptr = ntree;
+  }
+  else {
+    BLI_assert(owner_id == NULL);
   }
 
   BLI_strncpy(ntree->idname, idname, sizeof(ntree->idname));
@@ -2597,6 +2592,19 @@ bNodeTree *ntreeAddTree(Main *bmain, const char *name, const char *idname)
   return ntree;
 }
 
+bNodeTree *ntreeAddTree(Main *bmain, const char *name, const char *idname)
+{
+  return ntreeAddTree_do(bmain, nullptr, false, name, idname);
+}
+
+bNodeTree *ntreeAddTreeEmbedded(Main *UNUSED(bmain),
+                                ID *owner_id,
+                                const char *name,
+                                const char *idname)
+{
+  return ntreeAddTree_do(nullptr, owner_id, true, name, idname);
+}
+
 bNodeTree *ntreeCopyTree_ex(const bNodeTree *ntree, Main *bmain, const bool do_id_user)
 {
   const int flag = do_id_user ? 0 : LIB_ID_CREATE_NO_USER_REFCOUNT | LIB_ID_CREATE_NO_MAIN;
diff --git a/source/blender/blenkernel/intern/scene.cc b/source/blender/blenkernel/intern/scene.cc
index 02f47a5ee35..71c77be5b46 100644
--- a/source/blender/blenkernel/intern/scene.cc
+++ b/source/blender/blenkernel/intern/scene.cc
@@ -216,7 +216,7 @@ static void scene_init_data(ID *id)
   }
 
   /* Master Collection */
-  scene->master_collection = BKE_collection_master_add();
+  scene->master_collection = BKE_collection_master_add(scene);
 
   BKE_view_layer_add(scene, "ViewLayer", nullptr, VIEWLAYER_ADD_NEW);
 }
diff --git a/source/blender/blenkernel/intern/simulation.cc b/source/blender/blenkernel/intern/simulation.cc
index 260d67de4d8..6afb698bcc0 100644
--- a/source/blender/blenkernel/intern/simulation.cc
+++ b/source/blender/blenkernel/intern/simulation.cc
@@ -51,8 +51,7 @@ static void simulation_init_data(ID *id)
 
   MEMCPY_STRUCT_AFTER(simulation, DNA_struct_default_get(Simulation), id);
 
-  bNodeTree *ntree = ntreeAddTree(nullptr, "Geometry Nodetree", ntreeType_Geometry->idname);
-  simulation->nodetree = ntree;
+  ntreeAddTreeEmbedded(nullptr, id, "Geometry Nodetree", ntreeType_Geometry->idname);
 }
 
 static void simulation_copy_data(Main *bmain, ID *id_dst, const ID *id_src, const int flag)
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index d178c8fcd4c..863f978daaf 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -2052,7 +2052,7 @@ static void direct_link_id_embedded_id(BlendDataReader *reader,
                           (ID *)*nodetree,
                           id_old != NULL ? (ID *)ntreeFromID(id_old) : NULL,
                           0);
-    ntreeBlendReadData(reader, *nodetree);
+    ntreeBlendReadData(reader, id, *nodetree);
   }
 
   if (GS(id->name) == ID_SCE) {
@@ -2064,7 +2064,7 @@ static void direct_link_id_embedded_id(BlendDataReader *reader,
                             &scene->master_collection->id,
                             id_old != NULL ? &((Scene *)id_old)->master_collection->id : NULL,
                             0);
-      BKE_collection_blend_read_data(reader, scene->master_collection);
+      BKE_collection_blend_read_data(reader, scene->master_collection, &scene->id);
     }
   }
 }
diff --git a/source/blender/blenloader/intern/versioning_280.c b/source/blender/blenloader/intern/versioning_280.c
index cd2132ddae9..c1ea96aaedc 100644
--- a/source/blender/blenloader/intern/versioning_280.c
+++ b/source/blender/blenloader/intern/versioning_280.c
@@ -367,7 +367,7 @@ static void do_version_scene_collection_to_collection(Main *bmain, Scene *scene)
   BLI_listbase_clear(&scene->view_layers);
 
   if (!scene->master_collection) {
-    scene->master_collection = BKE_collection_master_add();
+    scene->master_collection = BKE_collection_master_add(scene);
   }
 
   /* Convert scene collections. */
@@ -411,7 +411,7 @@ static void do_version_layers_to_collections(Main *bmain, Scene *scene)
   /* Since we don't have access to FileData we check the (always valid) first
    * render layer instead. */
   if (!scene->master_collection) {
-    scene->master_collection = BKE_collection_master_add();
+    scene->master_collection = BKE_collection_master_add(scene);
   }
 
   if (scene->view_layers.first) {
diff --git a/source/blender/draw/engines/eevee/eevee_shaders.c b/source/blender/draw/engines/eevee/eevee_shaders.c
index e7b6cd636ae..04d1168a30d 100644
--- a/source/blender/draw/engines/eevee/eevee_shaders.c
+++ b/source/blender/draw/engines/eevee/eevee_shaders.c
@@ -1192,8 +1192,8 @@ Material *EEVEE_material_default_diffuse_get(void)
   if (!e_data.diffuse_mat) {
     Material *ma = BKE_id_new_nomain(ID_MA, "EEVEEE default diffuse");
 
-    bNodeTree *ntree = ntreeAddTree(NULL, "Shader Nodetree", ntreeType_Shader->idname);
-    ma->nodetree = ntree;
+    bNodeTree *ntree = ntreeAddTreeEmbedded(
+        NULL, &ma->id, "Shader Nodetree", ntreeType_Shader->idname);
     ma->use_nodes = true;
 
     bNode *bsdf = nodeAddStaticNode(NULL, ntree, SH_NODE_BSDF_DIFFUSE);
@@ -1219,8 +1219,8 @@ Material *EEVEE_material_default_glossy_get(void)
   if (!e_data.glossy_mat) {
     Material *ma = BKE_id_new_nomain(ID_MA, "EEVEEE default metal");
 
-    bNodeTree *ntree = ntreeAddTree(NULL, "Shader Nodetree", ntreeType_Shader->idname);
-    ma->nodetree = ntree;
+    bNodeTree *ntree = ntreeAddTreeEmbedded(
+        NULL, &ma->id, "Shader Nodetree", ntreeType_Shader->idname);
     ma->use_nodes = true;
 
     bNode *bsdf = nodeAddStaticNode(NULL, ntree, SH_NODE_BSDF_GLOSSY);
@@ -1248,8 +1248,8 @@ Material *EEVEE_material_default_error_get(void)
   if (!e_data.error_mat) {
     Material *ma = BKE_id_new_nomain(ID_MA, "EEVEEE default error");
 
-    bNodeTree *ntree = ntreeAddTree(NULL, "Shader Nodetree", ntreeType_Shader->idname);
-    ma->nodetree = ntree;
+    bNodeTree *ntree = ntreeAddTreeEmbedded(
+        NULL, &ma->id, "Shader Nodetree", ntreeType_Shader->idname);
     ma->use_nodes = true;
 
     /* Use emission and output material to be compatible with both World and Material. */
diff --git a/source/blender/draw/engines/eevee_next/eevee_material.cc b/source/blender/draw/engines/eevee_next/eevee_material.cc
index 13efbd1bd1a..a92f96e8c70 100644
--- a/source/blender/draw/engines/eevee_next/eevee_material.cc
+++ b/source/blender/draw/engines/eevee_next/eevee_material.cc
@@ -72,10 +72,9 @@ bNodeTree *DefaultSurfaceNodeTree::nodetree_get(::Material *ma)
 MaterialModule::MaterialModule(Instance &inst) : inst_(inst)
 {
   {
-    bNodeTree *ntree = ntreeAddTree(nullptr, "Shader Nodetree", ntreeType_Shader->idname);
-
     diffuse_mat = (::Material *)BKE_id_new_nomain(ID_MA, "EEVEE default diffuse");
-    diffuse_mat->nodetree = ntree;
+    bNodeTree *ntree = ntreeAddTreeEmbedded(
+        nullptr, &diffuse_mat->id, "Shader Nodetree", ntreeType_Shader->idname);
     diffuse_mat->use_nodes = true;
     /* To use the forward pipeline. */
     diffuse_mat->blend_method = MA_BM_BLEND;
@@ -95,10 +94,9 @@ MaterialModule::MaterialModule(Instance &inst) : inst_(inst)
     nodeSetActive(ntree, output);
   }
   {
-    bNodeTree *ntree = ntreeAddTree(nullptr, "Shader Nodetree", ntreeType_Shader->idname);
-
     glossy_mat = (::Material *)BKE_id_new_nomain(ID_MA, "EEVEE default metal");
-    glossy_mat->nodetree = ntree;
+    bNodeTree *ntree = ntreeAddTreeEmbedded(
+        nullptr, &glossy_mat->id, "Shader Nodetree", ntreeType_Shader->idname);
     glossy_mat->use_nodes = true;
     /* To use the forward pipeline. */
     glossy_mat->blend_method = MA_BM_BLEND;
@@ -120,10 +118,9 @@ MaterialModule::MaterialModule(Instance &inst) : inst_(inst)
     nodeSetActive(ntree, output);
   }
   {
-    bNodeTree *ntree = ntreeAddTree(nullptr, "Shader Nodetree", ntreeType_Shader->idname);
-
     error_mat_ = (::Material *)BKE_id_new_nomain(ID_MA, "EEVEE default error");
-    error_mat_->nodetree = ntree;
+    bNodeTree *ntree = ntreeAddTreeEmbedded(
+        nullptr, &error_mat_->id, "Shader Nodetree", ntreeType_Shader->idname);
     error_mat_->use_nodes = true;
 
     /* Use emission and output material to be compatible with both World and Material. */
diff --git a/source/blender/editors/space_node/node_edit.cc b/source/blender/editors/space_node/node_edit.cc
index 5f92e514385..9167b96b76f 100644
--- a/source/blender/editors/space_node/node_edit.cc
+++ b/source/blender/editors/space_node/node_edit.cc
@@ -506,12 +506,12 @@ void ED_node_shader_default(const bContext *C, ID *id)
   }
   else if (ELEM(GS(id->name), ID_WO, ID_LA)) {
     /* Emission */
-    bNodeTree *ntree = ntreeAddTree(nullptr, "Shader Nodetree", ntreeType_Shader->idname);
+    bNodeTree *ntree = ntreeAddTreeEmbedded(
+        nullptr, id, "Shader Nodetree", ntreeType_Shader->idname);
     bNode *shader, *output;
 
     if (GS(id->name) == ID_WO) {
       World *world = (World *)id;
-      world->nodetree = ntree;
 
       shader = nodeAddStaticNode(nullptr, ntree, SH_NODE_BACKGROUND);
       output = nodeAddStaticNode(nullptr, ntree, SH_NODE_OUTPUT_WORLD);
@@ -525,9 +525,6 @@ void ED_node_shader_default(const bContext *C, ID *id)
       copy_v3_v3(((bNodeSocketValueRGBA *)color_sock->default_value)->value, &world->horr);
     }
     else {
-      Light *light = (Light *)id;
-      light->nodetree = ntree;
-
       shader = nodeAddStaticNode(nullptr, ntree, SH_NODE_EMISSION);
       output = nodeAddStaticNode(nullptr, ntree, SH_NODE_OUTPUT_LIGHT);
       nodeAddLink(ntree,
@@ -560,7 +557,8 @@ void ED_node_composit_default(const bContext *C, Scene *sce)
     return;
   }
 
-  sce->nodetree = ntreeAddTree(nullptr, "Compositing Nodetree", ntreeType_Composite->idname);
+  sce->nodetree = ntreeAddTreeEmbedded(
+      nullptr, &sce->id, "Compositing Nodetree", ntreeType_Composite->idname);
 
   sce->nodetree->chunksize = 256;
   sce->nodetree->edit_quality = NTREE_QUALITY_HIGH;
@@ -593,7 +591,8 @@ void ED_node_texture_default(const bContext *C, Tex *tex)
     return;
   }
 
-  tex->nodetree = ntreeAddTree(nullptr, "Texture Nodetree", ntreeType_Texture->idname);
+  tex->nodetree = ntreeAddTreeEmbedded(
+      nullptr, &tex->id, "Texture Nodetree", ntreeType_Texture->idname);
 
   bNode *out = nodeAddStaticNode(C, tex->nodetree, TEX_NODE_OUTPUT);
   out->locx = 300.0f;
diff --git a/source/blender/freestyle/intern/blender_interface/BlenderStrokeRenderer.cpp b/source/blender/freestyle/intern/blender_interface/BlenderStrokeRenderer.cpp
index 6365dfe26a7..dd041abfd1f 100644
--- a/source/blender/freestyle/intern/blender_interface/BlenderStrokeRenderer.cpp
+++ b/source/blender/freestyle/intern/blender_interface/BlenderStrokeRenderer.cpp
@@ -218,12 +218,12 @@ Material *BlenderStrokeRenderer::GetStrokeShader(Main *bmain,
         break;
       }
     }
+    ma->nodetree = ntree;
   }
   else {
-    ntree = ntreeAddTree(nullptr, "stroke_shader", "ShaderNodeTree");
+    ntree = ntreeAddTreeEmbedded(nullptr, &ma->id, "stroke_shader", "ShaderNodeTree");
   }
-  ma->nodetree = ntree;
-  ma->use_nodes = 1;
+  ma->use_nodes = true;
   ma->blend_method = MA_BM_HASHED;
 
   bNode *input_attr_color = nodeAddStaticNode(nullptr, ntree, SH_NODE_ATTRIBUTE);
diff --git a/source/blender/io/collada/Materials.cpp b/source/blender/io/collada/Materials.cpp
index b5d89d8d1cf..997da31b939 100644
--- a/source/blender/io/collada/Materials.cpp
+++ b/source/blender/io/collada/Materials.cpp
@@ -86,7 +86,7 @@ bNodeTree *MaterialNode::prepare_material_nodetree()
     return nullptr;
   }
 
-  material->nodetree = ntreeAddTree(nullptr, "Shader Nodetree", "ShaderNodeTree");
+  ntreeAddTreeEmbedded(nullptr, &material->id, "Shader Nodetree", "ShaderNodeTree");
   material->use_nodes = true;
   ntree = material->nodetree;
   return ntree;
diff --git a/source/blender/io/collada/collada_utils.cpp b/source/blender/io/collada/collada_utils.cpp
index 75842734b08..82c471a6524 100644
--- a/source/blender/io/collada/collada_utils.cpp
+++ b/source/blender/io/collada/collada_utils.cpp
@@ -1108,7 +1108,7 @@ static std::string bc_get_uvlayer_name(Mesh *me, int layer)
 static bNodeTree *prepare_material_nodetree(Material *ma)
 {
   if (ma->nodetree == nullptr) {
-    ma->nodetree = ntreeAddTree(nullptr, "Shader Nodetree", "ShaderNodeTree");
+    ntreeAddTreeEmbedded(nullptr, &ma->id, "Shader Nodetree", "ShaderNodeTree");
     ma->use_nodes = true;
   }
   return ma->nodetree;
diff --git a/source/blender/io/usd/intern/usd_reader_material.cc b/source/blender/io/usd/intern/usd_reader_material.cc
index 4b72a075106..3546beb022c 100644
--- a/source/blender/io/usd/intern/usd_reader_material.cc
+++ b/source/blender/io/usd/intern/usd_reader_material.cc
@@ -353,8 +353,7 @@ void USDMaterialReader::import_usd_preview(Material *mtl,
    * and output shaders. */
 
   /* Add the node tree. */
-  bNodeTree *ntree = ntreeAddTree(nullptr, "Shader Nodetree", "ShaderNodeTree");
-  mtl->nodetree = ntree;
+  bNodeTree *ntree = ntreeAddTreeEmbedded(nullptr, &mtl->id, "Shader Nodetree", "ShaderNodeTree");
   mtl->use_nodes = true;
 
   /* Create the Principled BSDF shader node. */
diff --git a/source/blender/io/wavefront_obj/importer/obj_import_mtl.cc b/source/blender/io/wavefront_obj/importer/obj_import_mtl.cc
index 58d414a59ad..0922a71979e 100644
--- a/source/blender/io/wavefront_obj/importer/obj_import_mtl.cc
+++ b/source/blender/io/wavefront_obj/importer/obj_import_mtl.cc
@@ -380,7 +380,8 @@ bNodeTree *create_mtl_node_tree(Main *bmain,
                                 Material *mat,
                                 bool relative_paths)
 {
-  bNodeTree *ntree = ntreeAddTree(nullptr, "Shader Nodetree", ntreeType_Shader->idname);
+  bNodeTree *ntree = ntreeAddTreeEmbedded(
+      nullptr, &mat->id, "Shader Nodetree", ntreeType_Shader->idname);
 
   bNode *bsdf = add_node(ntree, SH_NODE_BSDF_PRINCIPLED, node_locx_bsdf, node_locy_top);
   bNode *output = add_node(ntree, SH_NODE_OUTPUT_MATERIAL, node_locx_output, node_locy_top);
diff --git a/source/blender/makesdna/DNA_collection_types.h b/source/blender/makesdna/DNA_collection_types.h
index 26011c990d4..a3e5eb4e944 100644
--- a/source/blender/makesdna/DNA_collection_types.h
+++ b/source/blender/makesdna/DNA_collection_types.h
@@ -46,6 +46,9 @@ enum eCollectionLineArt_Flags {
 typedef struct Collection {
   ID id;
 
+  /** The ID owning this node tree, in case it is an embedded one. */
+  ID *owner_id;
+
   /** CollectionObject. */
   ListBase gobject;
   /** CollectionChild. */
diff --git a/source/blender/makesdna/DNA_node_types.h b/source/blender/makesdna/DNA_node_types.h
index 07e9f5d8c52..0114988a0bc 100644
--- a/source/blender/makesdna/DNA_node_types.h
+++ b/source/blender/makesdna/DNA_node_types.h
@@ -535,6 +535,9 @@ typedef struct bNodeTree {
   /** Animation data (must be immediately after id for utilities to use it). */
   struct AnimData *adt;
 
+  /** The ID owning this node tree, in case it is an embedded one. */
+  ID *owner_id;
+
   /** Runtime type information. */
   struct bNodeTreeType *typeinfo;
   /** Runtime type identifier. */