From: "Theodore Ts'o" <tytso@mit.edu>
To: linux-ext4@vger.kernel.org
Subject: [PATCH, E2FSPROGS] On-disk format definition group desciptor checksums
Date: Wed, 18 Oct 2006 02:23:14 -0400 [thread overview]
Message-ID: <E1Ga4pe-0004rB-Cj@candygram.thunk.org> (raw)
Comments?
- Ted
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" <tytso@mit.edu>
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
next reply other threads:[~2006-10-18 6:23 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-18 6:23 Theodore Ts'o [this message]
2006-10-18 19:28 ` [PATCH, E2FSPROGS] On-disk format definition group desciptor checksums Andreas Dilger
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