From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752712AbXJUIEH (ORCPT ); Sun, 21 Oct 2007 04:04:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751255AbXJUIDu (ORCPT ); Sun, 21 Oct 2007 04:03:50 -0400 Received: from wa-out-1112.google.com ([209.85.146.180]:31522 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751194AbXJUIDs (ORCPT ); Sun, 21 Oct 2007 04:03:48 -0400 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=gC2OUf8d17iYVCciNJ1lQunJsZl6/GeFaaMzfJlaT5y3GoJs17Aahu/1Y/LdIfyNFk2ukgYkvCkQCDmbnsc544WPzOBJesK1cVDNeGGJXQilg9lvcXXItDAPMdxk1xzj/0CztHPNy+GpLPJS5seiK9bMAilD1V4pWLAuORv6FQY= Message-ID: Date: Sun, 21 Oct 2007 16:03:47 +0800 From: "Nai XIA" To: linux-kernel@vger.kernel.org Subject: The meaning of first_logical_block in do_mpage_readpage MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org hi, it may be a stupid question, but I am not quite clear about what "first_logical_block" is used for as one of parameters of "do_mpage_readpage". I searched all the source code and I found that "first_logical_block" always equals zero when passed to "do_mpage_readpage" and is used only in scope of "do_mpage_readpage". This makes me wonder about: 1. when should "first_logical_block" passed as non-zero values ? 2. why "first_logical_block" is one of args of "do_mpage_readpage" instead of being a local variable of it ? ( it seems that no one uses "first_logical_block" outside "do_mpage_readpage") Anyone can help me out . Thanks in advance!