How to insert ContentDocumentLink in Salesforce?

ContentVersion cVersion = new ContentVersion();
cVersion.ContentLocation = 'S'; //S-Document is in Salesforce. E-Document is outside of Salesforce. L-Document is on a Social Netork.
cVersion.PathOnClient = attach.Name;//File name with extention
cVersion.Origin = 'H';//C-Content Origin. H-Chatter Origin.
cVersion.OwnerId = attach.OwnerId;//Owner of the file
cVersion.Title = attach.Name;//Name of the file
cVersion.VersionData = attach.Body;//File content
Insert cVersion;

//After saved the Content Verison, get the ContentDocumentId
Id conDocument = [SELECT ContentDocumentId FROM ContentVersion WHERE Id =:cVersion.Id].ContentDocumentId;

//Insert ContentDocumentLink
ContentDocumentLink cDocLink = new ContentDocumentLink();
cDocLink.ContentDocumentId = conDocument;//Add ContentDocumentId
cDocLink.LinkedEntityId = attach.ParentId;//Add attachment parentId
cDocLink.ShareType = 'I';//V - Viewer permission. C - Collaborator permission. I - Inferred permission.
cDocLink.Visibility = 'InternalUsers';//AllUsers, InternalUsers, SharedUsers
Insert cDocLink;