From: "Aneesh Kumar K.V" Subject: Re: Buffer state bits Date: Thu, 27 Aug 2009 18:03:18 +0530 Message-ID: <20090827123318.GA19422@skywalker.linux.vnet.ibm.com> References: <20090826200021.GA5716@duck.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, Andrew Morton To: Jan Kara Return-path: Received: from e23smtp07.au.ibm.com ([202.81.31.140]:34373 "EHLO e23smtp07.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751298AbZH0MdX (ORCPT ); Thu, 27 Aug 2009 08:33:23 -0400 Content-Disposition: inline In-Reply-To: <20090826200021.GA5716@duck.novell.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: > > BH_Mapped > - Buffer has a physical block backing it stored in b_bdev + b_blocknr. This bit > is set by filesystem's get_block() function (or by VFS itself for block device > mappings). > > XXX: Some filesystems set BH_Mapped even for buffers that do no really > have the backing block (like buffers for delayed allocation). I think > we should get rid of it... > Also we don't want get_block to be called multiple times for the same file offset. __block_prepare_write does get_block looking at the BH_Mapped flag. ie one of reason delay and unwritten buffer_heads are also marked mapped. -aneesh