code: public boolean hardLinkTo(String src, String dst) throws IOException {  
      INode dstNode = hardLinkToInternal(src, dst); 
      getEditLog().logSync(false);  
      if (dstNode != null && auditLog.isInfoEnabled()) {  
  			logAuditEvent(getCurrentUGI(), Server.getRemoteIp(),
          "hardlink", src, dst, dstNode);
      } 
      return dstNode != null; 
    }
docs: Create the hard link from src file to the dest file.