Only check LFS integrity for first branch in push

changelogs/unreleased/jej-fix-slow-lfs-object-check.yml

+---
+title: Only check LFS integrity for first ref in a push to avoid timeout
+merge_request: 17098
+author:
+type: performance

lib/gitlab/checks/change_access.rb

@@ -16,11 +16,11 @@ module Gitlab
         lfs_objects_missing: 'LFS objects are missing. Ensure LFS is properly set up or try a manual "git lfs push --all".'
       }.freeze
 
-      attr_reader :user_access, :project, :skip_authorization, :protocol, :oldrev, :newrev, :ref, :branch_name, :tag_name
+      attr_reader :user_access, :project, :skip_authorization, :skip_lfs_integrity_check, :protocol, :oldrev, :newrev, :ref, :branch_name, :tag_name
 
       def initialize(
         change, user_access:, project:, skip_authorization: false,
-        protocol:
+        skip_lfs_integrity_check: false, protocol:
       )
         @oldrev, @newrev, @ref = change.values_at(:oldrev, :newrev, :ref)
         @branch_name = Gitlab::Git.branch_name(@ref)
@@ -28,6 +28,7 @@ module Gitlab
         @user_access = user_access
         @project = project
         @skip_authorization = skip_authorization
+        @skip_lfs_integrity_check = skip_lfs_integrity_check
         @protocol = protocol
       end
 
@@ -37,7 +38,7 @@ module Gitlab
         push_checks
         branch_checks
         tag_checks
-        lfs_objects_exist_check
+        lfs_objects_exist_check unless skip_lfs_integrity_check
         commits_check unless skip_commits_check
 
         true

lib/gitlab/git_access.rb

@@ -238,19 +238,22 @@ module Gitlab
       changes_list = Gitlab::ChangesList.new(changes)
 
       # Iterate over all changes to find if user allowed all of them to be applied
-      changes_list.each do |change|
+      changes_list.each.with_index do |change, index|
+        first_change = index == 0
+
         # If user does not have access to make at least one change, cancel all
         # push by allowing the exception to bubble up
-        check_single_change_access(change)
+        check_single_change_access(change, skip_lfs_integrity_check: !first_change)
       end
     end
 
-    def check_single_change_access(change)
+    def check_single_change_access(change, skip_lfs_integrity_check: false)
       Checks::ChangeAccess.new(
         change,
         user_access: user_access,
         project: project,
         skip_authorization: deploy_key?,
+        skip_lfs_integrity_check: skip_lfs_integrity_check,
         protocol: protocol
       ).exec
     end

lib/gitlab/git_access_wiki.rb

@@ -13,7 +13,7 @@ module Gitlab
       authentication_abilities.include?(:download_code) && user_access.can_do_action?(:download_wiki_code)
     end
 
-    def check_single_change_access(change)
+    def check_single_change_access(change, _options = {})
       unless user_access.can_do_action?(:create_wiki)
         raise UnauthorizedError, ERROR_MESSAGES[:write_to_wiki]
       end

spec/lib/gitlab/git_access_spec.rb

@@ -18,8 +18,9 @@ describe Gitlab::GitAccess do
                 redirected_path: redirected_path)
   end
 
-  let(:push_access_check) { access.check('git-receive-pack', '_any') }
-  let(:pull_access_check) { access.check('git-upload-pack', '_any') }
+  let(:changes) { '_any' }
+  let(:push_access_check) { access.check('git-receive-pack', changes) }
+  let(:pull_access_check) { access.check('git-upload-pack', changes) }
 
   describe '#check with single protocols allowed' do
     def disable_protocol(protocol)
@@ -646,6 +647,20 @@ describe Gitlab::GitAccess do
     end
   end
 
+  describe 'check LFS integrity' do
+    let(:changes) { ['6f6d7e7ed 570e7b2ab refs/heads/master', '6f6d7e7ed 570e7b2ab refs/heads/feature'] }
+
+    before do
+      project.add_developer(user)
+    end
+
+    it 'checks LFS integrity only for first change' do
+      expect_any_instance_of(Gitlab::Checks::LfsIntegrity).to receive(:objects_missing?).exactly(1).times
+
+      push_access_check
+    end
+  end
+
   describe '#check_push_access!' do
     before do
       merge_into_protected_branch