Remove the `ForkedProjectLink` model

This removes the `ForkedProjectLink` model that has been replaced by
the `ForkNetworkMember` and `ForkNetwork` combination. All existing
relations have been adjusted to use these new models.

The `forked_project_link` table has been dropped.

The "Forks" count on the admin dashboard has been updated to count all
`ForkNetworkMember` rows and deduct the number of `ForkNetwork`
rows. This is because now the "root-project" of a fork network also
has a `ForkNetworkMember` row. This count could become inaccurate when
the root of a fork network is deleted.

34 files changed, 217 insertions, 251 deletions

diff --git a/app/controllers/admin/dashboard_controller.rb b/app/controllers/admin/dashboard_controller.rb
index b5fb5511638..23cc9ee247a 100644
--- a/app/controllers/admin/dashboard_controller.rb
+++ b/app/controllers/admin/dashboard_controller.rb
@@ -3,8 +3,8 @@
 class Admin::DashboardController < Admin::ApplicationController
   include CountHelper
 
-  COUNTED_ITEMS = [Project, User, Group, ForkedProjectLink, Issue, MergeRequest,
-                   Note, Snippet, Key, Milestone].freeze
+  COUNTED_ITEMS = [Project, User, Group, ForkNetworkMember, ForkNetwork, Issue,
+                   MergeRequest, Note, Snippet, Key, Milestone].freeze
 
   # rubocop: disable CodeReuse/ActiveRecord
   def index
diff --git a/app/helpers/count_helper.rb b/app/helpers/count_helper.rb
index e16223a82c9..13839474e1f 100644
--- a/app/helpers/count_helper.rb
+++ b/app/helpers/count_helper.rb
@@ -8,4 +8,18 @@ module CountHelper
 
     number_with_delimiter(count)
   end
+
+  # This will approximate the fork count by checking all counting all fork network
+  # memberships, and deducting 1 for each root of the fork network.
+  # This might be inacurate as the root of the fork network might have been deleted.
+  #
+  # This makes querying this information a lot more effecient and it should be
+  # accurate enough for the instance wide statistics
+  def approximate_fork_count_with_delimiters(count_data)
+    fork_network_count = count_data[ForkNetwork]
+    fork_network_member_count = count_data[ForkNetworkMember]
+    approximate_fork_count = fork_network_member_count - fork_network_count
+
+    number_with_delimiter(approximate_fork_count)
+  end
 end
diff --git a/app/models/forked_project_link.rb b/app/models/forked_project_link.rb
deleted file mode 100644
index 0f7067238cd..00000000000
--- a/app/models/forked_project_link.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-# frozen_string_literal: true
-
-class ForkedProjectLink < ActiveRecord::Base
-  belongs_to :forked_to_project, -> { where.not(pending_delete: true) }, class_name: 'Project'
-  belongs_to :forked_from_project, -> { where.not(pending_delete: true) }, class_name: 'Project'
-end
diff --git a/app/models/project.rb b/app/models/project.rb
index c7ca322853f..7a447592568 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -164,20 +164,15 @@ class Project < ActiveRecord::Base
   has_one :packagist_service
   has_one :hangouts_chat_service
 
-  # TODO: replace these relations with the fork network versions
-  has_one  :forked_project_link,  foreign_key: "forked_to_project_id"
-  has_one  :forked_from_project,  through:   :forked_project_link
-
-  has_many :forked_project_links, foreign_key: "forked_from_project_id"
-  has_many :forks,                through:     :forked_project_links, source: :forked_to_project
-  # TODO: replace these relations with the fork network versions
-
   has_one :root_of_fork_network,
           foreign_key: 'root_project_id',
           inverse_of: :root_project,
           class_name: 'ForkNetwork'
   has_one :fork_network_member
   has_one :fork_network, through: :fork_network_member
+  has_one :forked_from_project, through: :fork_network_member
+  has_many :forked_to_members, class_name: 'ForkNetworkMember', foreign_key: 'forked_from_project_id'
+  has_many :forks, through: :forked_to_members, source: :project, inverse_of: :forked_from_project
 
   has_one :import_state, autosave: true, class_name: 'ProjectImportState', inverse_of: :project
   has_one :import_export_upload, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
@@ -1247,12 +1242,7 @@ class Project < ActiveRecord::Base
   end
 
   def forked?
-    return true if fork_network && fork_network.root_project != self
-
-    # TODO: Use only the above conditional using the `fork_network`
-    # This is the old conditional that looks at the `forked_project_link`, we
-    # fall back to this while we're migrating the new models
-    !(forked_project_link.nil? || forked_project_link.forked_from_project.nil?)
+    fork_network && fork_network.root_project != self
   end
 
   def fork_source
@@ -1543,9 +1533,7 @@ class Project < ActiveRecord::Base
   def visibility_level_allowed_as_fork?(level = self.visibility_level)
     return true unless forked?
 
-    # self.forked_from_project will be nil before the project is saved, so
-    # we need to go through the relation
-    original_project = forked_project_link&.forked_from_project
+    original_project = fork_source
     return true unless original_project
 
     level <= original_project.visibility_level
diff --git a/app/services/projects/create_service.rb b/app/services/projects/create_service.rb
index 0e6a7e8da54..20bfe5af7a1 100644
--- a/app/services/projects/create_service.rb
+++ b/app/services/projects/create_service.rb
@@ -13,8 +13,8 @@ module Projects
         return ::Projects::CreateFromTemplateService.new(current_user, params).execute
       end
 
-      forked_from_project_id = params.delete(:forked_from_project_id)
       import_data = params.delete(:import_data)
+      relations_block = params.delete(:relations_block)
 
       @project = Project.new(params)
 
@@ -24,11 +24,6 @@ module Projects
         return @project
       end
 
-      unless allowed_fork?(forked_from_project_id)
-        @project.errors.add(:forked_from_project_id, 'is forbidden')
-        return @project
-      end
-
       set_project_name_from_path
 
       # get namespace id
@@ -47,6 +42,7 @@ module Projects
         @project.namespace_id = current_user.namespace_id
       end
 
+      relations_block&.call(@project)
       yield(@project) if block_given?
 
       # If the block added errors, don't try to save the project
@@ -54,10 +50,6 @@ module Projects
 
       @project.creator = current_user
 
-      if forked_from_project_id
-        @project.build_forked_project_link(forked_from_project_id: forked_from_project_id)
-      end
-
       save_project_and_import_data(import_data)
 
       after_create_actions if @project.persisted?
@@ -80,15 +72,6 @@ module Projects
     end
 
     # rubocop: disable CodeReuse/ActiveRecord
-    def allowed_fork?(source_project_id)
-      return true if source_project_id.nil?
-
-      source_project = Project.find_by(id: source_project_id)
-      current_user.can?(:fork_project, source_project)
-    end
-    # rubocop: enable CodeReuse/ActiveRecord
-
-    # rubocop: disable CodeReuse/ActiveRecord
     def allowed_namespace?(user, namespace_id)
       namespace = Namespace.find_by(id: namespace_id)
       current_user.can?(:create_projects, namespace)
diff --git a/app/services/projects/fork_service.rb b/app/services/projects/fork_service.rb
index cbbb88a9410..8dc0e044875 100644
--- a/app/services/projects/fork_service.rb
+++ b/app/services/projects/fork_service.rb
@@ -12,31 +12,42 @@ module Projects
 
     private
 
+    def allowed_fork?
+      current_user.can?(:fork_project, @project)
+    end
+
     def link_existing_project(fork_to_project)
       return if fork_to_project.forked?
 
-      link_fork_network(fork_to_project)
+      build_fork_network_member(fork_to_project)
 
-      # A forked project stores its LFS objects in the `forked_from_project`.
-      # So the LFS objects become inaccessible, and therefore delete them from
-      # the database so they'll get cleaned up.
-      #
-      # TODO: refactor this to get the correct lfs objects when implementing
-      #       https://gitlab.com/gitlab-org/gitlab-ce/issues/39769
-      fork_to_project.lfs_objects_projects.delete_all
+      if link_fork_network(fork_to_project)
+        # A forked project stores its LFS objects in the `forked_from_project`.
+        # So the LFS objects become inaccessible, and therefore delete them from
+        # the database so they'll get cleaned up.
+        #
+        # TODO: refactor this to get the correct lfs objects when implementing
+        #       https://gitlab.com/gitlab-org/gitlab-ce/issues/39769
+        fork_to_project.lfs_objects_projects.delete_all
 
-      fork_to_project
+        fork_to_project
+      end
     end
 
     def fork_new_project
       new_params = {
-        forked_from_project_id: @project.id,
         visibility_level:       allowed_visibility_level,
         description:            @project.description,
         name:                   @project.name,
         path:                   @project.path,
         shared_runners_enabled: @project.shared_runners_enabled,
-        namespace_id:           target_namespace.id
+        namespace_id:           target_namespace.id,
+        fork_network:           fork_network,
+        # We need to assign the fork network membership after the project has
+        # been instantiated to avoid ActiveRecord trying to create it when
+        # initializing the project, as that would cause a foreign key constraint
+        # exception.
+        relations_block:        -> (project) { build_fork_network_member(project) }
       }
 
       if @project.avatar.present? && @project.avatar.image?
@@ -46,38 +57,35 @@ module Projects
       new_project = CreateService.new(current_user, new_params).execute
       return new_project unless new_project.persisted?
 
+      # Set the forked_from_project relation after saving to avoid having to
+      # reload the project to reset the association information and cause an
+      # extra query.
+      new_project.forked_from_project = @project
+
       builds_access_level = @project.project_feature.builds_access_level
       new_project.project_feature.update(builds_access_level: builds_access_level)
 
-      link_fork_network(new_project)
-
       new_project
     end
 
     def fork_network
-      if @project.fork_network
-        @project.fork_network
-      elsif forked_from_project = @project.forked_from_project
-        # TODO: remove this case when all background migrations have completed
-        # this only happens when a project had a `forked_project_link` that was
-        # not migrated to the `fork_network` relation
-        forked_from_project.fork_network || forked_from_project.create_root_of_fork_network
+      @fork_network ||= @project.fork_network || @project.build_root_of_fork_network
+    end
+
+    def build_fork_network_member(fork_to_project)
+      if allowed_fork?
+        fork_to_project.build_fork_network_member(forked_from_project: @project,
+                                                  fork_network: fork_network)
       else
-        @project.create_root_of_fork_network
+        fork_to_project.errors.add(:forked_from_project_id, 'is forbidden')
       end
     end
 
     def link_fork_network(fork_to_project)
-      fork_network.fork_network_members.create(project: fork_to_project,
-                                               forked_from_project: @project)
-
-      # TODO: remove this when ForkedProjectLink model is removed
-      unless fork_to_project.forked_project_link
-        fork_to_project.create_forked_project_link(forked_to_project: fork_to_project,
-                                                   forked_from_project: @project)
-      end
+      return if fork_to_project.errors.any?
 
-      refresh_forks_count
+      fork_to_project.fork_network_member.save &&
+        refresh_forks_count
     end
 
     def refresh_forks_count
diff --git a/app/services/projects/forks_count_service.rb b/app/services/projects/forks_count_service.rb
index 00e73148358..ca85e2dc281 100644
--- a/app/services/projects/forks_count_service.rb
+++ b/app/services/projects/forks_count_service.rb
@@ -9,10 +9,7 @@ module Projects
 
     # rubocop: disable CodeReuse/ActiveRecord
     def self.query(project_ids)
-      # We can't directly change ForkedProjectLink to ForkNetworkMember here
-      # Nowadays, when a call using v3 to projects/:id/fork is made,
-      # the relationship to ForkNetworkMember is not updated
-      ForkedProjectLink.where(forked_from_project: project_ids)
+      ForkNetworkMember.where(forked_from_project: project_ids)
     end
     # rubocop: enable CodeReuse/ActiveRecord
   end
diff --git a/app/services/projects/move_forks_service.rb b/app/services/projects/move_forks_service.rb
index 2948555a17c..33f0bab12c9 100644
--- a/app/services/projects/move_forks_service.rb
+++ b/app/services/projects/move_forks_service.rb
@@ -6,7 +6,6 @@ module Projects
       return unless super && source_project.fork_network
 
       Project.transaction(requires_new: true) do
-        move_forked_project_links
         move_fork_network_members
         update_root_project
         refresh_forks_count
@@ -18,18 +17,6 @@ module Projects
     private
 
     # rubocop: disable CodeReuse/ActiveRecord
-    def move_forked_project_links
-      # Update ancestor
-      ForkedProjectLink.where(forked_to_project: source_project)
-                       .update_all(forked_to_project_id: @project.id)
-
-      # Update the descendants
-      ForkedProjectLink.where(forked_from_project: source_project)
-                       .update_all(forked_from_project_id: @project.id)
-    end
-    # rubocop: enable CodeReuse/ActiveRecord
-
-    # rubocop: disable CodeReuse/ActiveRecord
     def move_fork_network_members
       ForkNetworkMember.where(project: source_project).update_all(project_id: @project.id)
       ForkNetworkMember.where(forked_from_project: source_project).update_all(forked_from_project_id: @project.id)
diff --git a/app/services/projects/unlink_fork_service.rb b/app/services/projects/unlink_fork_service.rb
index a8b7c7f136a..1b8a920268f 100644
--- a/app/services/projects/unlink_fork_service.rb
+++ b/app/services/projects/unlink_fork_service.rb
@@ -25,7 +25,6 @@ module Projects
       end
 
       @project.fork_network_member.destroy
-      @project.forked_project_link.destroy
     end
     # rubocop: enable CodeReuse/ActiveRecord
 
diff --git a/app/views/admin/dashboard/index.html.haml b/app/views/admin/dashboard/index.html.haml
index 85c04f8a01d..7ac79cc77f5 100644
--- a/app/views/admin/dashboard/index.html.haml
+++ b/app/views/admin/dashboard/index.html.haml
@@ -42,7 +42,7 @@
             %p
               Forks
               %span.light.float-right
-                = approximate_count_with_delimiters(@counts, ForkedProjectLink)
+                = approximate_fork_count_with_delimiters(@counts)
             %p
               Issues
               %span.light.float-right
diff --git a/app/workers/namespaceless_project_destroy_worker.rb b/app/workers/namespaceless_project_destroy_worker.rb
index d9df42c9e17..2965f3b1150 100644
--- a/app/workers/namespaceless_project_destroy_worker.rb
+++ b/app/workers/namespaceless_project_destroy_worker.rb
@@ -32,7 +32,5 @@ class NamespacelessProjectDestroyWorker
     merge_requests = project.forked_from_project.merge_requests.opened.from_project(project)
 
     merge_requests.update_all(state: 'closed')
-
-    project.forked_project_link.destroy
   end
 end
diff --git a/lib/api/entities.rb b/lib/api/entities.rb
index 5a4b85f98cf..65855e8aac4 100644
--- a/lib/api/entities.rb
+++ b/lib/api/entities.rb
@@ -260,7 +260,7 @@ module API
         super(projects_relation).preload(:group)
                                 .preload(project_group_links: :group,
                                          fork_network: :root_project,
-                                         forked_project_link: :forked_from_project,
+                                         fork_network_member: :forked_from_project,
                                          forked_from_project: [:route, :forks, :tags, namespace: :route])
       end
       # rubocop: enable CodeReuse/ActiveRecord
diff --git a/spec/controllers/projects/merge_requests_controller_spec.rb b/spec/controllers/projects/merge_requests_controller_spec.rb
index 73b62dc1151..78581dc37a4 100644
--- a/spec/controllers/projects/merge_requests_controller_spec.rb
+++ b/spec/controllers/projects/merge_requests_controller_spec.rb
@@ -838,12 +838,14 @@ describe Projects::MergeRequestsController do
     end
 
     context 'with a forked project' do
-      let(:fork_project) { create(:project, :repository, forked_from_project: project) }
-      let(:fork_owner) { fork_project.owner }
+      let(:forked_project) { fork_project(project, fork_owner, repository: true) }
+      let(:fork_owner) { create(:user) }
 
       before do
-        merge_request.update!(source_project: fork_project)
-        fork_project.add_reporter(user)
+        project.add_developer(fork_owner)
+
+        merge_request.update!(source_project: forked_project)
+        forked_project.add_reporter(user)
       end
 
       context 'user cannot push to source branch' do
diff --git a/spec/factories/forked_project_links.rb b/spec/factories/forked_project_links.rb
deleted file mode 100644
index bc59fea81ec..00000000000
--- a/spec/factories/forked_project_links.rb
+++ /dev/null
@@ -1,15 +0,0 @@
-FactoryBot.define do
-  factory :forked_project_link do
-    association :forked_to_project, factory: [:project, :repository]
-    association :forked_from_project, factory: [:project, :repository]
-
-    after(:create) do |link|
-      link.forked_from_project.reload
-      link.forked_to_project.reload
-    end
-
-    trait :forked_to_empty_project do
-      association :forked_to_project, factory: [:project, :repository]
-    end
-  end
-end
diff --git a/spec/features/admin/dashboard_spec.rb b/spec/features/admin/dashboard_spec.rb
new file mode 100644
index 00000000000..a6ca0803469
--- /dev/null
+++ b/spec/features/admin/dashboard_spec.rb
@@ -0,0 +1,28 @@
+require 'spec_helper'
+
+describe 'admin visits dashboard' do
+  include ProjectForksHelper
+
+  before do
+    sign_in(create(:admin))
+  end
+
+  context 'counting forks' do
+    it 'correctly counts 2 forks of a project' do
+      project = create(:project)
+      project_fork = fork_project(project)
+      fork_project(project_fork)
+
+      # Make sure the fork_networks & fork_networks reltuples have been updated
+      # to get a correct count on postgresql
+      if Gitlab::Database.postgresql?
+        ActiveRecord::Base.connection.execute('ANALYZE fork_networks')
+        ActiveRecord::Base.connection.execute('ANALYZE fork_network_members')
+      end
+
+      visit admin_root_path
+
+      expect(page).to have_content('Forks 2')
+    end
+  end
+end
diff --git a/spec/features/merge_request/user_edits_mr_spec.rb b/spec/features/merge_request/user_edits_mr_spec.rb
index 8c9e782aa76..3152707136c 100644
--- a/spec/features/merge_request/user_edits_mr_spec.rb
+++ b/spec/features/merge_request/user_edits_mr_spec.rb
@@ -1,11 +1,13 @@
 require 'rails_helper'
 
 describe 'Merge request > User edits MR' do
+  include ProjectForksHelper
+
   it_behaves_like 'an editable merge request'
 
   context 'for a forked project' do
     it_behaves_like 'an editable merge request' do
-      let(:source_project) { create(:project, :repository, forked_from_project: target_project) }
+      let(:source_project) { fork_project(target_project, nil, repository: true) }
     end
   end
 end
diff --git a/spec/features/merge_request/user_sees_mr_from_deleted_forked_project_spec.rb b/spec/features/merge_request/user_sees_mr_from_deleted_forked_project_spec.rb
index 029b66b5e8e..fc4a188d4a7 100644
--- a/spec/features/merge_request/user_sees_mr_from_deleted_forked_project_spec.rb
+++ b/spec/features/merge_request/user_sees_mr_from_deleted_forked_project_spec.rb
@@ -1,18 +1,20 @@
 require 'rails_helper'
 
 describe 'Merge request > User sees MR from deleted forked project', :js do
+  include ProjectForksHelper
+
   let(:project) { create(:project, :public, :repository) }
   let(:user) { project.creator }
-  let(:fork_project) { create(:project, :public, :repository, forked_from_project: project) }
+  let(:forked_project) { fork_project(project, nil, repository: true) }
   let!(:merge_request) do
-    create(:merge_request_with_diffs, source_project: fork_project,
+    create(:merge_request_with_diffs, source_project: forked_project,
                                       target_project: project,
                                       description: 'Test merge request')
   end
 
   before do
     MergeRequests::MergeService.new(project, user).execute(merge_request)
-    fork_project.destroy!
+    forked_project.destroy!
     sign_in(user)
     visit project_merge_request_path(project, merge_request)
   end
diff --git a/spec/features/merge_request/user_sees_notes_from_forked_project_spec.rb b/spec/features/merge_request/user_sees_notes_from_forked_project_spec.rb
index d4ad0b0a377..a6118453540 100644
--- a/spec/features/merge_request/user_sees_notes_from_forked_project_spec.rb
+++ b/spec/features/merge_request/user_sees_notes_from_forked_project_spec.rb
@@ -1,18 +1,20 @@
 require 'rails_helper'
 
 describe 'Merge request > User sees notes from forked project', :js do
+  include ProjectForksHelper
+
   let(:project) { create(:project, :public, :repository) }
   let(:user) { project.creator }
-  let(:fork_project) { create(:project, :public, :repository, forked_from_project: project) }
+  let(:forked_project) { fork_project(project, nil, repository: true) }
   let!(:merge_request) do
-    create(:merge_request_with_diffs, source_project: fork_project,
+    create(:merge_request_with_diffs, source_project: forked_project,
                                       target_project: project,
                                       description: 'Test merge request')
   end
 
   before do
     create(:note_on_commit, note: 'A commit comment',
-                            project: fork_project,
+                            project: forked_project,
                             commit_id: merge_request.commit_shas.first)
     sign_in(user)
   end
diff --git a/spec/features/merge_request/user_sees_pipelines_from_forked_project_spec.rb b/spec/features/merge_request/user_sees_pipelines_from_forked_project_spec.rb
index d30dcefc6aa..97093bbc2f6 100644
--- a/spec/features/merge_request/user_sees_pipelines_from_forked_project_spec.rb
+++ b/spec/features/merge_request/user_sees_pipelines_from_forked_project_spec.rb
@@ -1,17 +1,19 @@
 require 'rails_helper'
 
 describe 'Merge request > User sees pipelines from forked project', :js do
+  include ProjectForksHelper
+
   let(:target_project) { create(:project, :public, :repository) }
   let(:user) { target_project.creator }
-  let(:fork_project) { create(:project, :repository, forked_from_project: target_project) }
+  let(:forked_project) { fork_project(target_project, nil, repository: true) }
   let!(:merge_request) do
-    create(:merge_request_with_diffs, source_project: fork_project,
+    create(:merge_request_with_diffs, source_project: forked_project,
                                       target_project: target_project,
                                       description: 'Test merge request')
   end
   let(:pipeline) do
     create(:ci_pipeline,
-           project: fork_project,
+           project: forked_project,
            sha: merge_request.diff_head_sha,
            ref: merge_request.source_branch)
   end
diff --git a/spec/finders/fork_projects_finder_spec.rb b/spec/finders/fork_projects_finder_spec.rb
index f0cef7ea406..b3fdffc3331 100644
--- a/spec/finders/fork_projects_finder_spec.rb
+++ b/spec/finders/fork_projects_finder_spec.rb
@@ -1,20 +1,21 @@
 require 'spec_helper'
 
 describe ForkProjectsFinder do
-  let(:source_project) { create(:project, :empty_repo) }
-  let(:private_fork) { create(:project, :private, :empty_repo, name: 'A') }
-  let(:internal_fork) { create(:project, :internal, :empty_repo, name: 'B') }
-  let(:public_fork) { create(:project, :public, :empty_repo, name: 'C') }
+  include ProjectForksHelper
+
+  let(:source_project) { create(:project, :public, :empty_repo) }
+  let(:private_fork) { fork_project(source_project, nil, name: 'A') }
+  let(:internal_fork) { fork_project(source_project, nil, name: 'B') }
+  let(:public_fork) { fork_project(source_project, nil, name: 'C') }
 
   let(:non_member) { create(:user) }
   let(:private_fork_member) { create(:user) }
 
   before do
+    private_fork.update!(visibility_level: Gitlab::VisibilityLevel::PRIVATE)
     private_fork.add_developer(private_fork_member)
 
-    source_project.forks << private_fork
-    source_project.forks << internal_fork
-    source_project.forks << public_fork
+    internal_fork.update!(visibility_level: Gitlab::VisibilityLevel::INTERNAL)
   end
 
   describe '#execute' do
diff --git a/spec/helpers/visibility_level_helper_spec.rb b/spec/helpers/visibility_level_helper_spec.rb
index a3be222b7bd..e565ac8c530 100644
--- a/spec/helpers/visibility_level_helper_spec.rb
+++ b/spec/helpers/visibility_level_helper_spec.rb
@@ -1,6 +1,8 @@
 require 'spec_helper'
 
 describe VisibilityLevelHelper do
+  include ProjectForksHelper
+
   let(:project)          { build(:project) }
   let(:group)            { build(:group) }
   let(:personal_snippet) { build(:personal_snippet) }
@@ -83,13 +85,13 @@ describe VisibilityLevelHelper do
 
   describe "disallowed_visibility_level?" do
     describe "forks" do
-      let(:project)       { create(:project, :internal) }
-      let(:fork_project)  { create(:project, forked_from_project: project) }
+      let(:project) { create(:project, :internal) }
+      let(:forked_project) { fork_project(project) }
 
       it "disallows levels" do
-        expect(disallowed_visibility_level?(fork_project, Gitlab::VisibilityLevel::PUBLIC)).to be_truthy
-        expect(disallowed_visibility_level?(fork_project, Gitlab::VisibilityLevel::INTERNAL)).to be_falsey
-        expect(disallowed_visibility_level?(fork_project, Gitlab::VisibilityLevel::PRIVATE)).to be_falsey
+        expect(disallowed_visibility_level?(forked_project, Gitlab::VisibilityLevel::PUBLIC)).to be_truthy
+        expect(disallowed_visibility_level?(forked_project, Gitlab::VisibilityLevel::INTERNAL)).to be_falsey
+        expect(disallowed_visibility_level?(forked_project, Gitlab::VisibilityLevel::PRIVATE)).to be_falsey
       end
     end
 
diff --git a/spec/lib/gitlab/import_export/all_models.yml b/spec/lib/gitlab/import_export/all_models.yml
index fe167033941..a63f34b5536 100644
--- a/spec/lib/gitlab/import_export/all_models.yml
+++ b/spec/lib/gitlab/import_export/all_models.yml
@@ -229,9 +229,8 @@ project:
 - mock_ci_service
 - mock_deployment_service
 - mock_monitoring_service
-- forked_project_link
+- forked_to_members
 - forked_from_project
-- forked_project_links
 - forks
 - merge_requests
 - fork_merge_requests
diff --git a/spec/models/forked_project_link_spec.rb b/spec/models/forked_project_link_spec.rb
deleted file mode 100644
index 32e33e8f42f..00000000000
--- a/spec/models/forked_project_link_spec.rb
+++ /dev/null
@@ -1,68 +0,0 @@
-require 'spec_helper'
-
-describe ForkedProjectLink, "add link on fork" do
-  include ProjectForksHelper
-
-  let(:project_from) { create(:project, :repository) }
-  let(:project_to) { fork_project(project_from, user) }
-  let(:user) { create(:user) }
-
-  before do
-    project_from.add_reporter(user)
-  end
-
-  it 'project_from knows its forks' do
-    _ = project_to
-
-    expect(project_from.forks.count).to eq(1)
-  end
-
-  it "project_to knows it is forked" do
-    expect(project_to.forked?).to be_truthy
-  end
-
-  it "project knows who it is forked from" do
-    expect(project_to.forked_from_project).to eq(project_from)
-  end
-
-  context 'project_to is pending_delete' do
-    before do
-      project_to.update!(pending_delete: true)
-    end
-
-    it { expect(project_from.forks.count).to eq(0) }
-  end
-
-  context 'project_from is pending_delete' do
-    before do
-      project_from.update!(pending_delete: true)
-    end
-
-    it { expect(project_to.forked_from_project).to be_nil }
-  end
-
-  describe '#forked?' do
-    let(:project_to) { create(:project, :repository, forked_project_link: forked_project_link) }
-    let(:forked_project_link) { create(:forked_project_link) }
-
-    before do
-      forked_project_link.forked_from_project = project_from
-      forked_project_link.forked_to_project = project_to
-      forked_project_link.save!
-    end
-
-    it "project_to knows it is forked" do
-      expect(project_to.forked?).to be_truthy
-    end
-
-    it "project_from is not forked" do
-      expect(project_from.forked?).to be_falsey
-    end
-
-    it "project_to.destroy destroys fork_link" do
-      project_to.destroy
-
-      expect(ForkedProjectLink.exists?(id: forked_project_link.id)).to eq(false)
-    end
-  end
-end
diff --git a/spec/models/project_spec.rb b/spec/models/project_spec.rb
index 3fecddefff2..ecfa7771b02 100644
--- a/spec/models/project_spec.rb
+++ b/spec/models/project_spec.rb
@@ -23,7 +23,6 @@ describe Project do
     it { is_expected.to have_many(:deploy_keys) }
     it { is_expected.to have_many(:hooks) }
     it { is_expected.to have_many(:protected_branches) }
-    it { is_expected.to have_one(:forked_project_link) }
     it { is_expected.to have_one(:slack_service) }
     it { is_expected.to have_one(:microsoft_teams_service) }
     it { is_expected.to have_one(:mattermost_service) }
@@ -56,7 +55,7 @@ describe Project do
     it { is_expected.to have_one(:statistics).class_name('ProjectStatistics') }
     it { is_expected.to have_one(:import_data).class_name('ProjectImportData') }
     it { is_expected.to have_one(:last_event).class_name('Event') }
-    it { is_expected.to have_one(:forked_from_project).through(:forked_project_link) }
+    it { is_expected.to have_one(:forked_from_project).through(:fork_network_member) }
     it { is_expected.to have_one(:auto_devops).class_name('ProjectAutoDevops') }
     it { is_expected.to have_many(:commit_statuses) }
     it { is_expected.to have_many(:pipelines) }
@@ -77,7 +76,8 @@ describe Project do
     it { is_expected.to have_many(:lfs_objects_projects) }
     it { is_expected.to have_many(:project_group_links) }
     it { is_expected.to have_many(:notification_settings).dependent(:delete_all) }
-    it { is_expected.to have_many(:forks).through(:forked_project_links) }
+    it { is_expected.to have_many(:forked_to_members).class_name('ForkNetworkMember') }
+    it { is_expected.to have_many(:forks).through(:forked_to_members) }
     it { is_expected.to have_many(:uploads) }
     it { is_expected.to have_many(:pipeline_schedules) }
     it { is_expected.to have_many(:members_and_requesters) }
@@ -1359,7 +1359,7 @@ describe Project do
 
     context 'when checking on forked project' do
       let(:project)        { create(:project, :internal) }
-      let(:forked_project) { create(:project, forked_from_project: project) }
+      let(:forked_project) { fork_project(project) }
 
       it { expect(forked_project.visibility_level_allowed?(Gitlab::VisibilityLevel::PRIVATE)).to be_truthy }
       it { expect(forked_project.visibility_level_allowed?(Gitlab::VisibilityLevel::INTERNAL)).to be_truthy }
@@ -1971,9 +1971,12 @@ describe Project do
     let(:import_jid) { '123' }
 
     context 'forked' do
-      let(:forked_project_link) { create(:forked_project_link, :forked_to_empty_project) }
-      let(:forked_from_project) { forked_project_link.forked_from_project }
-      let(:project) { forked_project_link.forked_to_project }
+      let(:forked_from_project) { create(:project, :repository) }
+      let(:project) { create(:project) }
+
+      before do
+        fork_project(forked_from_project, nil, target_project: project)
+      end
 
       it 'schedules a RepositoryForkWorker job' do
         expect(RepositoryForkWorker).to receive(:perform_async).with(project.id).and_return(import_jid)
@@ -2260,6 +2263,12 @@ describe Project do
       end
     end
 
+    describe '#forks' do
+      it 'includes direct forks of the project' do
+        expect(project.forks).to contain_exactly(forked_project)
+      end
+    end
+
     describe '#lfs_storage_project' do
       it 'returns self for non-forks' do
         expect(project.lfs_storage_project).to eq project
diff --git a/spec/requests/api/projects_spec.rb b/spec/requests/api/projects_spec.rb
index c8e98e6024c..22e5a7c7174 100644
--- a/spec/requests/api/projects_spec.rb
+++ b/spec/requests/api/projects_spec.rb
@@ -1196,7 +1196,7 @@ describe API::Projects do
 
           expect(response).to have_gitlab_http_status(201)
           expect(project_fork_target.forked_from_project.id).to eq(project_fork_source.id)
-          expect(project_fork_target.forked_project_link).to be_present
+          expect(project_fork_target.fork_network_member).to be_present
           expect(project_fork_target).to be_forked
         end
 
diff --git a/spec/serializers/merge_request_widget_entity_spec.rb b/spec/serializers/merge_request_widget_entity_spec.rb
index 0ba2539a717..5bf8aa7f23f 100644
--- a/spec/serializers/merge_request_widget_entity_spec.rb
+++ b/spec/serializers/merge_request_widget_entity_spec.rb
@@ -1,6 +1,8 @@
 require 'spec_helper'
 
 describe MergeRequestWidgetEntity do
+  include ProjectForksHelper
+
   let(:project)  { create :project, :repository }
   let(:resource) { create(:merge_request, source_project: project, target_project: project) }
   let(:user)     { create(:user) }
@@ -206,12 +208,12 @@ describe MergeRequestWidgetEntity do
 
   describe 'when source project is deleted' do
     let(:project) { create(:project, :repository) }
-    let(:fork_project) { create(:project, :repository, forked_from_project: project) }
-    let(:merge_request) { create(:merge_request, source_project: fork_project, target_project: project) }
+    let(:forked_project) { fork_project(project) }
+    let(:merge_request) { create(:merge_request, source_project: forked_project, target_project: project) }
 
     it 'returns a blank rebase_path' do
       allow(merge_request).to receive(:should_be_rebased?).and_return(true)
-      fork_project.destroy
+      forked_project.destroy
       merge_request.reload
 
       entity = described_class.new(merge_request, request: request).as_json
diff --git a/spec/services/projects/create_service_spec.rb b/spec/services/projects/create_service_spec.rb
index a80c8a7fe51..08de27ca44a 100644
--- a/spec/services/projects/create_service_spec.rb
+++ b/spec/services/projects/create_service_spec.rb
@@ -295,6 +295,17 @@ describe Projects::CreateService, '#execute' do
     end
   end
 
+  it 'calls the passed block' do
+    fake_block = double('block')
+    opts[:relations_block] = fake_block
+
+    expect_next_instance_of(Project) do |project|
+      expect(fake_block).to receive(:call).with(project)
+    end
+
+    create_project(user, opts)
+  end
+
   it 'writes project full path to .git/config' do
     project = create_project(user, opts)
     rugged = rugged_repo(project.repository)
diff --git a/spec/services/projects/destroy_service_spec.rb b/spec/services/projects/destroy_service_spec.rb
index 1d31d26f418..12ddf8447bd 100644
--- a/spec/services/projects/destroy_service_spec.rb
+++ b/spec/services/projects/destroy_service_spec.rb
@@ -259,7 +259,6 @@ describe Projects::DestroyService do
 
     before do
       project.lfs_objects << create(:lfs_object)
-      forked_project.forked_project_link.destroy
       forked_project.reload
     end
 
diff --git a/spec/services/projects/fork_service_spec.rb b/spec/services/projects/fork_service_spec.rb
index 947cb61038d..a3d24ae312a 100644
--- a/spec/services/projects/fork_service_spec.rb
+++ b/spec/services/projects/fork_service_spec.rb
@@ -31,6 +31,10 @@ describe Projects::ForkService do
 
           it { is_expected.not_to be_persisted }
           it { expect(subject.errors[:forked_from_project_id]).to eq(['is forbidden']) }
+
+          it 'does not create a fork network' do
+            expect { subject }.not_to change { @from_project.reload.fork_network }
+          end
         end
 
         describe "successfully creates project in the user namespace" do
@@ -70,6 +74,12 @@ describe Projects::ForkService do
             expect(fork_network.root_project).to eq(@from_project)
             expect(fork_network.projects).to contain_exactly(@from_project, to_project)
           end
+
+          it 'imports the repository of the forked project' do
+            to_project = fork_project(@from_project, @to_user, repository: true)
+
+            expect(to_project.empty_repo?).to be_falsy
+          end
         end
 
         context 'creating a fork of a fork' do
@@ -247,11 +257,13 @@ describe Projects::ForkService do
 
     context 'if project is not forked' do
       it 'creates fork relation' do
-        expect(fork_to_project.forked?).to be false
+        expect(fork_to_project.forked?).to be_falsy
         expect(forked_from_project(fork_to_project)).to be_nil
 
         subject.execute(fork_to_project)
 
+        fork_to_project.reload
+
         expect(fork_to_project.forked?).to be true
         expect(forked_from_project(fork_to_project)).to eq fork_from_project
         expect(fork_to_project.forked_from_project).to eq fork_from_project
@@ -272,6 +284,17 @@ describe Projects::ForkService do
           .to change { fork_to_project.lfs_objects_projects.count }
           .to(0)
       end
+
+      context 'if the fork is not allowed' do
+        let(:fork_from_project) { create(:project, :private) }
+
+        it 'does not delete the LFS objects' do
+          create(:lfs_objects_project, project: fork_to_project)
+
+          expect { subject.execute(fork_to_project) }
+            .not_to change { fork_to_project.lfs_objects_projects.size }
+        end
+      end
     end
   end
 end
diff --git a/spec/services/projects/unlink_fork_service_spec.rb b/spec/services/projects/unlink_fork_service_spec.rb
index 3ec6139bfa6..014aab44281 100644
--- a/spec/services/projects/unlink_fork_service_spec.rb
+++ b/spec/services/projects/unlink_fork_service_spec.rb
@@ -5,13 +5,12 @@ describe Projects::UnlinkForkService do
 
   subject { described_class.new(forked_project, user) }
 
-  let(:fork_link) { forked_project.forked_project_link }
   let(:project) { create(:project, :public) }
   let(:forked_project) { fork_project(project, user) }
   let(:user) { create(:user) }
 
   context 'with opened merge request on the source project' do
-    let(:merge_request) { create(:merge_request, source_project: forked_project, target_project: fork_link.forked_from_project) }
+    let(:merge_request) { create(:merge_request, source_project: forked_project, target_project: forked_project.forked_from_project) }
     let(:merge_request2) { create(:merge_request, source_project: forked_project, target_project: fork_project(project)) }
     let(:merge_request_in_fork) { create(:merge_request, source_project: forked_project, target_project: forked_project) }
 
@@ -35,12 +34,6 @@ describe Projects::UnlinkForkService do
     end
   end
 
-  it 'remove fork relation' do
-    expect(forked_project.forked_project_link).to receive(:destroy)
-
-    subject.execute
-  end
-
   it 'removes the link to the fork network' do
     expect(forked_project.fork_network_member).to be_present
     expect(forked_project.fork_network).to be_present
diff --git a/spec/support/helpers/project_forks_helper.rb b/spec/support/helpers/project_forks_helper.rb
index 2c501a2a27c..6a7132c3093 100644
--- a/spec/support/helpers/project_forks_helper.rb
+++ b/spec/support/helpers/project_forks_helper.rb
@@ -24,7 +24,7 @@ module ProjectForksHelper
       allow(service).to receive(:gitlab_shell).and_return(shell)
     end
 
-    forked_project = service.execute
+    forked_project = service.execute(params[:target_project])
 
     # Reload the both projects so they know about their newly created fork_network
     if forked_project.persisted?
diff --git a/spec/workers/namespaceless_project_destroy_worker_spec.rb b/spec/workers/namespaceless_project_destroy_worker_spec.rb
index eec110dfbfb..2f21a1321e1 100644
--- a/spec/workers/namespaceless_project_destroy_worker_spec.rb
+++ b/spec/workers/namespaceless_project_destroy_worker_spec.rb
@@ -71,10 +71,10 @@ describe NamespacelessProjectDestroyWorker do
           expect(merge_request.reload).to be_closed
         end
 
-        it 'destroys the link' do
+        it 'destroys fork network members' do
           subject.perform(project.id)
 
-          expect(parent_project.forked_project_links).to be_empty
+          expect(parent_project.forked_to_members).to be_empty
         end
       end
     end
diff --git a/spec/workers/rebase_worker_spec.rb b/spec/workers/rebase_worker_spec.rb
index 20aff020dbb..936b9deaecc 100644
--- a/spec/workers/rebase_worker_spec.rb
+++ b/spec/workers/rebase_worker_spec.rb
@@ -1,25 +1,23 @@
 require 'spec_helper'
 
 describe RebaseWorker, '#perform' do
+  include ProjectForksHelper
+
   context 'when rebasing an MR from a fork where upstream has protected branches' do
     let(:upstream_project) { create(:project, :repository) }
-    let(:fork_project) { create(:project, :repository) }
+    let(:forked_project) { fork_project(upstream_project, nil, repository: true) }
 
     let(:merge_request) do
       create(:merge_request,
-             source_project: fork_project,
+             source_project: forked_project,
              source_branch: 'feature_conflict',
              target_project: upstream_project,
              target_branch: 'master')
     end
 
-    before do
-      create(:forked_project_link, forked_to_project: fork_project, forked_from_project: upstream_project)
-    end
-
     it 'sets the correct project for running hooks' do
       expect(MergeRequests::RebaseService)
-        .to receive(:new).with(fork_project, merge_request.author).and_call_original
+        .to receive(:new).with(forked_project, merge_request.author).and_call_original
 
       subject.perform(merge_request, merge_request.author)
     end
diff --git a/spec/workers/repository_fork_worker_spec.rb b/spec/workers/repository_fork_worker_spec.rb
index ac8716ecfb1..781f91ac9ca 100644
--- a/spec/workers/repository_fork_worker_spec.rb
+++ b/spec/workers/repository_fork_worker_spec.rb
@@ -1,6 +1,8 @@
 require 'spec_helper'
 
 describe RepositoryForkWorker do
+  include ProjectForksHelper
+
   describe 'modules' do
     it 'includes ProjectImportOptions' do
       expect(described_class).to include_module(ProjectImportOptions)
@@ -8,9 +10,13 @@ describe RepositoryForkWorker do
   end
 
   describe "#perform" do
-    let(:project) { create(:project, :repository) }
+    let(:project) { create(:project, :public, :repository) }
     let(:shell) { Gitlab::Shell.new }
-    let(:fork_project) { create(:project, :repository, :import_scheduled, forked_from_project: project) }
+    let(:forked_project) { create(:project, :repository, :import_scheduled) }
+
+    before do
+      fork_project(project, forked_project.creator, target_project: forked_project, repository: true)
+    end
 
     shared_examples 'RepositoryForkWorker performing' do
       before do
@@ -21,8 +27,8 @@ describe RepositoryForkWorker do
         expect(shell).to receive(:fork_repository).with(
           'default',
           project.disk_path,
-          fork_project.repository_storage,
-          fork_project.disk_path
+          forked_project.repository_storage,
+          forked_project.disk_path
         )
       end
 
@@ -49,28 +55,28 @@ describe RepositoryForkWorker do
 
         perform!
 
-        expect(fork_project.protected_branches.first.name).to eq(fork_project.default_branch)
+        expect(forked_project.protected_branches.first.name).to eq(forked_project.default_branch)
       end
 
       it 'flushes various caches' do
         expect_fork_repository.and_return(true)
 
         # Works around https://github.com/rspec/rspec-mocks/issues/910
-        expect(Project).to receive(:find).with(fork_project.id).and_return(fork_project)
-        expect(fork_project.repository).to receive(:expire_emptiness_caches)
+        expect(Project).to receive(:find).with(forked_project.id).and_return(forked_project)
+        expect(forked_project.repository).to receive(:expire_emptiness_caches)
           .and_call_original
-        expect(fork_project.repository).to receive(:expire_exists_cache)
+        expect(forked_project.repository).to receive(:expire_exists_cache)
           .and_call_original
-        expect(fork_project.wiki.repository).to receive(:expire_emptiness_caches)
+        expect(forked_project.wiki.repository).to receive(:expire_emptiness_caches)
           .and_call_original
-        expect(fork_project.wiki.repository).to receive(:expire_exists_cache)
+        expect(forked_project.wiki.repository).to receive(:expire_exists_cache)
           .and_call_original
 
         perform!
       end
 
       it "handles bad fork" do
-        error_message = "Unable to fork project #{fork_project.id} for repository #{project.disk_path} -> #{fork_project.disk_path}"
+        error_message = "Unable to fork project #{forked_project.id} for repository #{project.disk_path} -> #{forked_project.disk_path}"
 
         expect_fork_repository.and_return(false)
 
@@ -80,7 +86,7 @@ describe RepositoryForkWorker do
 
     context 'only project ID passed' do
       def perform!
-        subject.perform(fork_project.id)
+        subject.perform(forked_project.id)
       end
 
       it_behaves_like 'RepositoryForkWorker performing'
@@ -88,7 +94,7 @@ describe RepositoryForkWorker do
 
     context 'project ID, storage and repo paths passed' do
       def perform!
-        subject.perform(fork_project.id, TestEnv.repos_path, project.disk_path)
+        subject.perform(forked_project.id, TestEnv.repos_path, project.disk_path)
       end
 
       it_behaves_like 'RepositoryForkWorker performing'