[Backport] Fix Deadlock & Delete affected reactions on comment deletion (#14392) (#14425)

* Enhance Ghost comment mitigation Settings (#14392)

* refactor models.DeleteComment and delete related reactions too

* use deleteComment for UserDeleteWithCommentsMaxDays in DeleteUser

* Resolve Fixme & fix potential deadlock

* rm refactor

* make diff eaven less

5 files changed, 23 insertions, 14 deletions

diff --git a/models/admin.go b/models/admin.go
index 903e35b0c9..b14f0e93fd 100644
--- a/models/admin.go
+++ b/models/admin.go
@@ -77,7 +77,7 @@ func removeStorageWithNotice(e Engine, bucket storage.ObjectStorage, title, path
 	if err := bucket.Delete(path); err != nil {
 		desc := fmt.Sprintf("%s [%s]: %v", title, path, err)
 		log.Warn(title+" [%s]: %v", path, err)
-		if err = createNotice(x, NoticeRepository, desc); err != nil {
+		if err = createNotice(e, NoticeRepository, desc); err != nil {
 			log.Error("CreateRepositoryNotice: %v", err)
 		}
 	}
diff --git a/models/issue_assignees.go b/models/issue_assignees.go
index 05e1797c19..6716f2fc70 100644
--- a/models/issue_assignees.go
+++ b/models/issue_assignees.go
@@ -82,7 +82,7 @@ func isUserAssignedToIssue(e Engine, issue *Issue, user *User) (isAssigned bool,
 }
 
 // ClearAssigneeByUserID deletes all assignments of an user
-func clearAssigneeByUserID(sess *xorm.Session, userID int64) (err error) {
+func clearAssigneeByUserID(sess Engine, userID int64) (err error) {
 	_, err = sess.Delete(&IssueAssignees{AssigneeID: userID})
 	return
 }
diff --git a/models/issue_comment.go b/models/issue_comment.go
index 73cbb0566f..b2a21e0f5b 100644
--- a/models/issue_comment.go
+++ b/models/issue_comment.go
@@ -1077,6 +1077,10 @@ func DeleteComment(comment *Comment, doer *User) error {
 		return err
 	}
 
+	if err := deleteReaction(sess, &ReactionOptions{Comment: comment}); err != nil {
+		return err
+	}
+
 	return sess.Commit()
 }
 
diff --git a/models/issue_reaction.go b/models/issue_reaction.go
index 50b9d6848a..1f1a483996 100644
--- a/models/issue_reaction.go
+++ b/models/issue_reaction.go
@@ -178,11 +178,15 @@ func CreateCommentReaction(doer *User, issue *Issue, comment *Comment, content s
 	})
 }
 
-func deleteReaction(e *xorm.Session, opts *ReactionOptions) error {
+func deleteReaction(e Engine, opts *ReactionOptions) error {
 	reaction := &Reaction{
-		Type:    opts.Type,
-		UserID:  opts.Doer.ID,
-		IssueID: opts.Issue.ID,
+		Type: opts.Type,
+	}
+	if opts.Doer != nil {
+		reaction.UserID = opts.Doer.ID
+	}
+	if opts.Issue != nil {
+		reaction.IssueID = opts.Issue.ID
 	}
 	if opts.Comment != nil {
 		reaction.CommentID = opts.Comment.ID
diff --git a/models/user.go b/models/user.go
index dc3b4142bf..f35d2e5c6b 100644
--- a/models/user.go
+++ b/models/user.go
@@ -40,7 +40,6 @@ import (
 	"golang.org/x/crypto/scrypt"
 	"golang.org/x/crypto/ssh"
 	"xorm.io/builder"
-	"xorm.io/xorm"
 )
 
 // UserType defines the user type
@@ -1020,8 +1019,7 @@ func deleteBeans(e Engine, beans ...interface{}) (err error) {
 	return nil
 }
 
-// FIXME: need some kind of mechanism to record failure. HINT: system notice
-func deleteUser(e *xorm.Session, u *User) error {
+func deleteUser(e Engine, u *User) error {
 	// Note: A user owns any repository or belongs to any organization
 	//	cannot perform delete operation.
 
@@ -1135,18 +1133,21 @@ func deleteUser(e *xorm.Session, u *User) error {
 		return fmt.Errorf("Delete: %v", err)
 	}
 
-	// FIXME: system notice
 	// Note: There are something just cannot be roll back,
 	//	so just keep error logs of those operations.
 	path := UserPath(u.Name)
-	if err := util.RemoveAll(path); err != nil {
-		return fmt.Errorf("Failed to RemoveAll %s: %v", path, err)
+	if err = util.RemoveAll(path); err != nil {
+		err = fmt.Errorf("Failed to RemoveAll %s: %v", path, err)
+		_ = createNotice(e, NoticeTask, fmt.Sprintf("delete user '%s': %v", u.Name, err))
+		return err
 	}
 
 	if len(u.Avatar) > 0 {
 		avatarPath := u.CustomAvatarRelativePath()
-		if err := storage.Avatars.Delete(avatarPath); err != nil {
-			return fmt.Errorf("Failed to remove %s: %v", avatarPath, err)
+		if err = storage.Avatars.Delete(avatarPath); err != nil {
+			err = fmt.Errorf("Failed to remove %s: %v", avatarPath, err)
+			_ = createNotice(e, NoticeTask, fmt.Sprintf("delete user '%s': %v", u.Name, err))
+			return err
 		}
 	}