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data=writeback mode is dangerous as it leads to higher data loss and stale data exposure when systems crash. It should not be the default, especially when all major distros ensure their ext3 filesystems default to ordered mode. Change the default mode to the safer data=ordered mode, because we should be caring far more about avoiding stale data exposure than performance. CC: linux-ext4@vger.kernel.org Signed-off-by: Dave Chinner <dchinner@redhat.com> Acked-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz>
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config EXT3_FS tristate "Ext3 journalling file system support" select JBD help This is the journalling version of the Second extended file system (often called ext3), the de facto standard Linux file system (method to organize files on a storage device) for hard disks.
The journalling code included in this driver means you do not have
to run e2fsck (file system checker) on your file systems after a
crash. The journal keeps track of any changes that were being made
at the time the system crashed, and can ensure that your file system
is consistent without the need for a lengthy check.
Other than adding the journal to the file system, the on-disk format
of ext3 is identical to ext2. It is possible to freely switch
between using the ext3 driver and the ext2 driver, as long as the
file system has been cleanly unmounted, or e2fsck is run on the file
system.
To add a journal on an existing ext2 file system or change the
behavior of ext3 file systems, you can use the tune2fs utility ("man
tune2fs"). To modify attributes of files and directories on ext3
file systems, use chattr ("man chattr"). You need to be using
e2fsprogs version 1.20 or later in order to create ext3 journals
(available at <http://sourceforge.net/projects/e2fsprogs/>).
To compile this file system support as a module, choose M here: the
module will be called ext3.
config EXT3_DEFAULTS_TO_ORDERED bool "Default to 'data=ordered' in ext3" depends on EXT3_FS default y help The journal mode options for ext3 have different tradeoffs between when data is guaranteed to be on disk and performance. The use of "data=writeback" can cause unwritten data to appear in files after an system crash or power failure, which can be a security issue. However, "data=ordered" mode can also result in major performance problems, including seconds-long delays before an fsync() call returns. For details, see:
http://ext4.wiki.kernel.org/index.php/Ext3_data_mode_tradeoffs
If you have been historically happy with ext3's performance,
data=ordered mode will be a safe choice and you should
answer 'y' here. If you understand the reliability and data
privacy issues of data=writeback and are willing to make
that trade off, answer 'n'.
config EXT3_FS_XATTR bool "Ext3 extended attributes" depends on EXT3_FS default y help Extended attributes are name:value pairs associated with inodes by the kernel or by users (see the attr(5) manual page, or visit http://acl.bestbits.at/ for details).
If unsure, say N.
You need this for POSIX ACL support on ext3.
config EXT3_FS_POSIX_ACL bool "Ext3 POSIX Access Control Lists" depends on EXT3_FS_XATTR select FS_POSIX_ACL help Posix Access Control Lists (ACLs) support permissions for users and groups beyond the owner/group/world scheme.
To learn more about Access Control Lists, visit the Posix ACLs for
Linux website <http://acl.bestbits.at/>.
If you don't know what Access Control Lists are, say N
config EXT3_FS_SECURITY bool "Ext3 Security Labels" depends on EXT3_FS_XATTR help Security labels support alternative access control models implemented by security modules like SELinux. This option enables an extended attribute handler for file security labels in the ext3 filesystem.
If you are not using a security module that requires using
extended attributes for file security labels, say N.