From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1767567AbXCIWYV (ORCPT ); Fri, 9 Mar 2007 17:24:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1767568AbXCIWYV (ORCPT ); Fri, 9 Mar 2007 17:24:21 -0500 Received: from ug-out-1314.google.com ([66.249.92.173]:42282 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1767567AbXCIWYU (ORCPT ); Fri, 9 Mar 2007 17:24:20 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=s7YP7lVS6oGTuEaWNIeWQVUJYA0vLGZU7NuB9EP+INvchkRJhCrE9rUJNByJf68sgWN9B+WP71xYgPO3dhrWcnH5ArTQFEmTCZDj4+Hh2+OFx0F0uZhKkss8OACeVJNlGh778TbSLpYClbuB/hZ2sC8l3GMvslT4G94MxXxqXfY= Message-ID: <4ae3c140703091424i25a0a3fcm6ba9d7bf348d04b6@mail.gmail.com> Date: Fri, 9 Mar 2007 17:24:18 -0500 From: "Xin Zhao" To: linux-kernel , linux-fsdevel Subject: question regarding the Linux block device cache MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, I am working on a file system that allow multiple files to share data blocks. That is, a data block can be shared by two or more files. Now my question is: suppose file A and B share the same data block D. Now a process open file A and read block D, then this process closes file A. If another process open file B and read block D right after the first process closes A, is the data of block D read from some cache or has to be loaded from disk again? I think this has to do with the Linux block device buffer cache. But I am not quite familiar with this part. Can someone help me or direct me to the right place to find the answer? Thanks in advance! -x