From: Andreas Dilger Subject: Re: [PATCH, E2FSPROGS] On-disk format definition group desciptor checksums Date: Wed, 18 Oct 2006 13:28:37 -0600 Message-ID: <20061018192837.GE3509@schatzie.adilger.int> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org Return-path: Received: from mail.clusterfs.com ([206.168.112.78]:57577 "EHLO mail.clusterfs.com") by vger.kernel.org with ESMTP id S1161295AbWJRT2n (ORCPT ); Wed, 18 Oct 2006 15:28:43 -0400 To: Theodore Ts'o Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Oct 18, 2006 02:23 -0400, Theodore Ts'o wrote: > On-disk format definition for group descriptor checksums > > - EXT4_FEATURE_RO_COMPAT_GDT_CSUM (0x0010?) - store a crc16 checksum in > the group descriptor (s_uuid[16] | __u32 group | ext3_group_desc > (excluding gd_checksum itself)). This allows the kernel to more safely > manage UNINIT groups. > > Signed-off-by: "Theodore Ts'o" Looks good to me. > Index: e2fsprogs/lib/ext2fs/ext2_fs.h > =================================================================== > --- e2fsprogs.orig/lib/ext2fs/ext2_fs.h 2006-10-18 02:20:35.000000000 -0400 > +++ e2fsprogs/lib/ext2fs/ext2_fs.h 2006-10-18 02:20:41.000000000 -0400 > @@ -144,7 +144,9 @@ > __u16 bg_free_inodes_count; /* Free inodes count */ > __u16 bg_used_dirs_count; /* Directories count */ > __u16 bg_flags; > - __u32 bg_reserved[3]; > + __u32 bg_reserved[2]; > + __u16 bg_itable_unused; /* Unused inodes count */ > + __u16 bg_checksum; /* crc16(s_uuid+grouo_num+group_desc)*/ > }; > > struct ext4_group_desc > @@ -601,6 +603,7 @@ > #define EXT2_FEATURE_RO_COMPAT_LARGE_FILE 0x0002 > /* #define EXT2_FEATURE_RO_COMPAT_BTREE_DIR 0x0004 not used */ > #define EXT4_FEATURE_RO_COMPAT_HUGE_FILE 0x0008 > +#define EXT4_FEATURE_RO_COMPAT_GDT_CSUM 0x0010 > > #define EXT2_FEATURE_INCOMPAT_COMPRESSION 0x0001 > #define EXT2_FEATURE_INCOMPAT_FILETYPE 0x0002 Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc.