From: Felipe Monteiro de Carvalho Subject: Re: Which features should I implement in my ext4 reader? Date: Wed, 14 Aug 2013 07:06:44 +0200 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 To: linux-ext4@vger.kernel.org Return-path: Received: from mail-pb0-f52.google.com ([209.85.160.52]:38915 "EHLO mail-pb0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751141Ab3HNFGp (ORCPT ); Wed, 14 Aug 2013 01:06:45 -0400 Received: by mail-pb0-f52.google.com with SMTP id wz12so8738344pbc.39 for ; Tue, 13 Aug 2013 22:06:44 -0700 (PDT) In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: Hello, Did my last message go through? Just wondering if it was lost ... thanks, Felipe Monteiro de Carvalho On Mon, Aug 12, 2013 at 5:38 PM, Felipe Monteiro de Carvalho wrote: > Hello, > > Thanks to the help here I have essentially finished my ext4 reader =) > At least it can read ext4 filesystems with these features, which is > what I found when using Ubuntu and Mageia LInux: > > EXT4_FEATURE_INCOMPAT_JOURNAL_DEV = $0008; // Journal device */ > EXT4_FEATURE_INCOMPAT_META_BG = $0010; > EXT4_FEATURE_INCOMPAT_EXTENTS = $0040; // extents support */ > EXT4_FEATURE_INCOMPAT_FLEX_BG = $0200; > EXT4_FEATURE_INCOMPAT_64BIT = $0080; > > Some features seam to not require any extra care for my reader: > > EXT4_FEATURE_INCOMPAT_COMPRESSION = $0001; > EXT4_FEATURE_INCOMPAT_FILETYPE = $0002; > EXT4_FEATURE_INCOMPAT_RECOVER = $0004; // Needs recovery */ > EXT4_FEATURE_INCOMPAT_BG_USE_META_CSUM= $2000; // use crc32c for bg */ > > But I now wonder about these features: > > EXT4_FEATURE_INCOMPAT_MMP = $0100; > EXT4_FEATURE_INCOMPAT_EA_INODE = $0400; // EA in inode */ > EXT4_FEATURE_INCOMPAT_DIRDATA = $1000; // data in dirent */ > EXT4_FEATURE_INCOMPAT_LARGEDIR = $4000; // >2GB or 3-lvl htree */ > EXT4_FEATURE_INCOMPAT_INLINEDATA = $8000; // data in inode */ > > Could anyone comment how common is the use of those features and if > they are already stable and in production usage (I read that they were > under development in 2011)? > > And also which ones require an active work for a reader application to > implement. As I already found out that FLEX_BG does not require active > work to be supported despite being in the INCOMPAT list... > > From the description I'm pretty sure that at least DIRDATA and > INLINEDATA would require adjustments in my software. But I wonder if > they are already being used and stable, etc, and if it is a good idea > to work on supporting them. > > thanks, =) > -- > Felipe Monteiro de Carvalho -- Felipe Monteiro de Carvalho