From: Zheng Liu Subject: Re: [PATCH 3/7 v2] ext4: add physical block and status member into extent status tree Date: Fri, 18 Jan 2013 17:49:34 +0800 Message-ID: <20130118094934.GA20442@gmail.com> References: <1357901627-3068-1-git-send-email-wenqing.lz@taobao.com> <1357901627-3068-4-git-send-email-wenqing.lz@taobao.com> <20130117044213.GA19734@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org, Jan kara , Zheng Liu To: Theodore Ts'o Return-path: Received: from mail-pb0-f43.google.com ([209.85.160.43]:48873 "EHLO mail-pb0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751032Ab3ARJfm (ORCPT ); Fri, 18 Jan 2013 04:35:42 -0500 Received: by mail-pb0-f43.google.com with SMTP id jt11so579010pbb.30 for ; Fri, 18 Jan 2013 01:35:41 -0800 (PST) Content-Disposition: inline In-Reply-To: <20130117044213.GA19734@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Jan 16, 2013 at 11:42:13PM -0500, Theodore Ts'o wrote: > On Fri, Jan 11, 2013 at 06:53:43PM +0800, Zheng Liu wrote: > > struct extent_status { > > struct rb_node rb_node; > > ext4_lblk_t es_lblk; /* first logical block extent covers */ > > ext4_lblk_t es_len; /* length of extent in block */ > > + ext4_fsblk_t es_pblk; /* first physical block */ > > + int es_status; /* record the status of extent */ > > }; > > Given that we only support 48 bits for the physical block number, and > we only need two bits for es_status, one thing we could do to save > memory is to stash the es_status bits in the top two bits of es_pblk. Thanks for the comment. In next version, es_status will be stashed into es_pblk. Regards, - Zheng