From: Andrew Morton Subject: Re: [PATCH] Ext4: Uninitialized Block Groups Date: Thu, 20 Sep 2007 16:22:08 -0700 Message-ID: <20070920162208.17f96f78.akpm@linux-foundation.org> References: <46F06C7B.20308@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, Andreas Dilger , cmm@us.ibm.com To: Avantika Mathur Return-path: Received: from smtp2.linux-foundation.org ([207.189.120.14]:47637 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751364AbXITXWh (ORCPT ); Thu, 20 Sep 2007 19:22:37 -0400 In-Reply-To: <46F06C7B.20308@linux.vnet.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Tue, 18 Sep 2007 17:25:31 -0700 Avantika Mathur wrote: > In pass1 of e2fsck, every inode table in the fileystem is scanned and checked, > regardless of whether it is in use. This is this the most time consuming part > of the filesystem check. The unintialized block group feature can greatly > reduce e2fsck time by eliminating checking of uninitialized inodes. > > With this feature, there is a a high water mark of used inodes for each block > group. Block and inode bitmaps can be uninitialized on disk via a flag in the > group descriptor to avoid reading or scanning them at e2fsck time. A checksum > of each group descriptor is used to ensure that corruption in the group > descriptor's bit flags does not cause incorrect operation. This needed a few fixups due to conflicts with ext2-ext3-ext4-add-block-bitmap-validation.patch but they were pretty straightforward. Please check that the result is OK.