Commit Graph

11 Commits

Author SHA1 Message Date
Diego Calleja
22359f5745 ext4: Update Documentation/filesystems/ext4.txt
Since Ext4 is supposed to be stable in 2.6.28-rc, ext4's documentation
file should be updated.

[ More updates also added by Theodore Ts'o. ]

Signed-off-by: Diego Calleja <diegocg@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2008-10-17 09:15:14 -04:00
Hidehiro Kawai
5bf5683a33 ext4: add an option to control error handling on file data
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>
2008-10-10 22:12:43 -04:00
Theodore Ts'o
03010a3350 ext4: Rename ext4dev to ext4
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>
2008-10-10 20:02:48 -04:00
Theodore Ts'o
240799cdf2 ext4: Use readahead when reading an inode from the inode table
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>
2008-10-09 23:53:47 -04:00
Theodore Ts'o
4537398d91 ext4: Update documentation to remind users to update mke2fs.conf
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2008-07-27 19:59:21 -04:00
Mingming Cao
49f1487b2e ext4: Documention update for new ordered mode and delayed allocation
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>
2008-07-11 19:27:31 -04:00
Jose R. Santos
93e3270c87 ext4: Documentation updates.
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>
2008-07-11 19:27:31 -04:00
Eric Sandeen
571640cad3 ext4: enable barriers by default
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>
2008-05-26 12:29:46 -04:00
Alex Tomas
c9de560ded ext4: Add multi block allocator for ext4
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>
2008-01-29 00:19:52 -05:00
Girish Shilamkar
818d276ceb 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>
2008-01-28 23:58:27 -05:00
Dave Kleikamp
fc513a333b [PATCH] Documentation/filesystems/ext4.txt
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>
2006-10-11 11:14:19 -07:00