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| author | Girish Shilamkar <girish@clusterfs.com> | 2008-01-28 23:58:27 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2008-01-28 23:58:27 -0500 |
| commit | 818d276ceb83aa9fdebb5e0a53188290312de987 (patch) | |
| tree | de3fb4ffadd72caea2876c5232ce76cd14b3646e /include/linux/ext4_fs.h | |
| parent | 8e85fb3f305b24b79c6d9cb7a56d22b062335ad3 (diff) | |
| download | lwn-818d276ceb83aa9fdebb5e0a53188290312de987.tar.gz lwn-818d276ceb83aa9fdebb5e0a53188290312de987.zip | |
ext4: Add the journal checksum feature
The journal checksum feature adds two new flags i.e
JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT and JBD2_FEATURE_COMPAT_CHECKSUM.
JBD2_FEATURE_CHECKSUM flag indicates that the commit block contains the
checksum for the blocks described by the descriptor blocks.
Due to checksums, writing of the commit record no longer needs to be
synchronous. Now commit record can be sent to disk without waiting for
descriptor blocks to be written to disk. This behavior is controlled
using JBD2_FEATURE_ASYNC_COMMIT flag. Older kernels/e2fsck should not be
able to recover the journal with _ASYNC_COMMIT hence it is made
incompat.
The commit header has been extended to hold the checksum along with the
type of the checksum.
For recovery in pass scan checksums are verified to ensure the sanity
and completeness(in case of _ASYNC_COMMIT) of every transaction.
Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
Signed-off-by: Girish Shilamkar <girish@clusterfs.com>
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Diffstat (limited to 'include/linux/ext4_fs.h')
| -rw-r--r-- | include/linux/ext4_fs.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h index 300cc5a5adb9..cd406dba0e64 100644 --- a/include/linux/ext4_fs.h +++ b/include/linux/ext4_fs.h @@ -467,7 +467,8 @@ do { \ #define EXT4_MOUNT_USRQUOTA 0x100000 /* "old" user quota */ #define EXT4_MOUNT_GRPQUOTA 0x200000 /* "old" group quota */ #define EXT4_MOUNT_EXTENTS 0x400000 /* Extents support */ - +#define EXT4_MOUNT_JOURNAL_CHECKSUM 0x800000 /* Journal checksums */ +#define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT 0x1000000 /* Journal Async Commit */ /* Compatibility, for having both ext2_fs.h and ext4_fs.h included at once */ #ifndef _LINUX_EXT2_FS_H #define clear_opt(o, opt) o &= ~EXT4_MOUNT_##opt |