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path: root/Documentation/filesystems/ext4.txt
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2008-10-10ext4: add an option to control error handling on file dataHidehiro Kawai
If the journal doesn't abort when it gets an IO error in file data blocks, the file data corruption will spread silently. Because most of applications and commands do buffered writes without fsync(), they don't notice the IO error. It's scary for mission critical systems. On the other hand, if the journal aborts whenever it gets an IO error in file data blocks, the system will easily become inoperable. So this patch introduces a filesystem option to determine whether it aborts the journal or just call printk() when it gets an IO error in file data. If you mount an ext4 fs with data_err=abort option, it aborts on file data write error. If you mount it with data_err=ignore, it doesn't abort, just call printk(). data_err=ignore is the default. Here is the corresponding patch of the ext3 version: http://kerneltrap.org/mailarchive/linux-kernel/2008/9/9/3239374 Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2008-10-10ext4: Rename ext4dev to ext4Theodore Ts'o
The ext4 filesystem is getting stable enough that it's time to drop the "dev" prefix. Also remove the requirement for the TEST_FILESYS flag. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2008-10-09ext4: Use readahead when reading an inode from the inode tableTheodore Ts'o
With modern hard drives, reading 64k takes roughly the same time as reading a 4k block. So request readahead for adjacent inode table blocks to reduce the time it takes when iterating over directories (especially when doing this in htree sort order) in a cold cache case. With this patch, the time it takes to run "git status" on a kernel tree after flushing the caches via "echo 3 > /proc/sys/vm/drop_caches" is reduced by 21%. Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2008-07-27ext4: Update documentation to remind users to update mke2fs.confTheodore Ts'o
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2008-07-11ext4: Documention update for new ordered mode and delayed allocationMingming Cao
Adding some documentations for delayed allocation and new ordered mode. Signed-off-by: Mingming Cao <cmm@us.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2008-07-11ext4: Documentation updates.Jose R. Santos
Some of the information in Documentation/filesystems/ext4.txt is out of date and in need of an update. Signed-off-by: Jose R. Santos <jrs@us.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2008-05-26ext4: enable barriers by defaultEric Sandeen
I can't think of any valid reason for ext4 to not use barriers when they are available; I believe this is necessary for filesystem integrity in the face of a volatile write cache on storage. An administrator who trusts that the cache is sufficiently battery- backed (and power supplies are sufficiently redundant, etc...) can always turn it back off again. SuSE has carried such a patch for ext3 for quite some time now. Also document the mount option while we're at it. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Mingming Cao <cmm@us.ibm.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2008-01-29ext4: Add multi block allocator for ext4Alex Tomas
Signed-off-by: Alex Tomas <alex@clusterfs.com> Signed-off-by: Andreas Dilger <adilger@clusterfs.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2008-01-28ext4: Add the journal checksum featureGirish Shilamkar
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>
2006-10-11[PATCH] Documentation/filesystems/ext4.txtDave Kleikamp
This file, ext4.txt, was put together with information from Andrew Morton, Andreas Dilger, Suparna Bhattacharya, and Ted Ts'o. I copied the mount options, with the exception of "extents", from ext3.txt, so if anyone is aware of anything out-of-date, please let me know. Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Suparna Bhattacharya <suparna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>