From: Andreas Dilger Subject: Re: [PATCH 15/41] whiteout: ext2 whiteout support Date: Wed, 21 Oct 2009 15:17:38 -0600 Message-ID: <1983FB3A-C88F-4EF4-A2E1-8B18DF97F0AB@sun.com> References: <1256152779-10054-1-git-send-email-vaurora@redhat.com> <1256152779-10054-2-git-send-email-vaurora@redhat.com> <1256152779-10054-3-git-send-email-vaurora@redhat.com> <1256152779-10054-4-git-send-email-vaurora@redhat.com> <1256152779-10054-5-git-send-email-vaurora@redhat.com> <1256152779-10054-6-git-send-email-vaurora@redhat.com> <1256152779-10054-7-git-send-email-vaurora@redhat.com> <1256152779-10054-8-git-send-email-vaurora@redhat.com> <1256152779-10054-9-git-send-email-vaurora@redhat.com> <1256152779-10054-10-git-send-email-vaurora@redhat.com> <1256152779-10054-11-git-send-email-vaurora@redhat.com> <1256152779-10054-12-git-send-email-vaurora@redhat.com> <1256152779-10054-13-git-send-email-vaurora@redhat.com> <1256152779-10054-14-git-send-email-vaurora@redhat.com> <1256152779-10054-15-git-send-email-vaurora@redhat.com> <1256152779-10054-16-git-send-email-vaurora@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; CHARSET=US-ASCII; delsp=yes; format=flowed Content-Transfer-Encoding: 7BIT Cc: Jan Blunck , Alexander Viro , Christoph Hellwig , Andy Whitcroft , Scott James Remnant , Sandu Popa Marius , Jan Rekorajski , "J. R. Okajima" , Arnd Bergmann , Vladimir Dronnikov , Felix Fietkau , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Theodore Tso , linux-ext4@vger.kernel.org To: Valerie Aurora Return-path: Received: from sca-es-mail-2.Sun.COM ([192.18.43.133]:44367 "EHLO sca-es-mail-2.sun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754015AbZJUVSN (ORCPT ); Wed, 21 Oct 2009 17:18:13 -0400 In-reply-to: <1256152779-10054-16-git-send-email-vaurora@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2009-10-21, at 13:19, Valerie Aurora wrote: > This patch adds whiteout support to EXT2. A whiteout is an empty > directory > entry (inode == 0) with the file type set to EXT2_FT_WHT. Therefore it > allocates space in directories. Due to being implemented as a > filetype it is > necessary to have the EXT2_FEATURE_INCOMPAT_FILETYPE flag set. > > diff --git a/include/linux/ext2_fs.h b/include/linux/ext2_fs.h > index 121720d..bd10826 100644 > --- a/include/linux/ext2_fs.h > +++ b/include/linux/ext2_fs.h > @@ -189,6 +189,7 @@ struct ext2_group_desc > +#define EXT2_OPAQUE_FL 0x00040000 Please check in the upstream e2fsprogs ext2_fs.h before defining new flag values for ext2/3/4. In this case, 0x40000 conflicts with EXT4_HUGE_FILE_FL, which is of course bad. > @@ -503,10 +504,12 @@ struct ext2_super_block { > #define EXT2_FEATURE_INCOMPAT_META_BG 0x0010 > +#define EXT2_FEATURE_INCOMPAT_WHITEOUT 0x0020 This one doesn't conflict, probably due to luck, because 0x0040-0x0200 are already in use for other features. I'm not sure if 0x0020 was reserved for some other use, or just skipped to avoid potential conflicts. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.