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config EXT4_FS
tristate "The Extended 4 (ext4) filesystem"
select JBD2
select CRC16
This is the next generation of the ext3 filesystem.
Unlike the change from ext2 filesystem to ext3 filesystem,
the on-disk format of ext4 is not forwards compatible with
ext3; it is based on extent maps and it supports 48-bit
physical block numbers. The ext4 filesystem also supports delayed
allocation, persistent preallocation, high resolution time stamps,
and a number of other features to improve performance and speed
up fsck time. For more information, please see the web pages at
The ext4 filesystem will support mounting an ext3
filesystem; while there will be some performance gains from
the delayed allocation and inode table readahead, the best
performance gains will require enabling ext4 features in the
filesystem, or formatting a new filesystem as an ext4
filesystem initially.
To compile this file system support as a module, choose M here. The
module will be called ext4.
If unsure, say N.
config EXT4_USE_FOR_EXT23
bool "Use ext4 for ext2/ext3 file systems"
depends on EXT4_FS
depends on EXT3_FS=n || EXT2_FS=n
default y
Allow the ext4 file system driver code to be used for ext2 or
ext3 file system mounts. This allows users to reduce their
compiled kernel size by using one file system driver for
ext2, ext3, and ext4 file systems.
config EXT4_FS_XATTR
bool "Ext4 extended attributes"
depends on EXT4_FS
default y
Extended attributes are name:value pairs associated with inodes by
the kernel or by users (see the attr(5) manual page, or visit
<> for details).
If unsure, say N.
You need this for POSIX ACL support on ext4.
bool "Ext4 POSIX Access Control Lists"
depends on EXT4_FS_XATTR
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 <>.
If you don't know what Access Control Lists are, say N
bool "Ext4 Security Labels"
depends on EXT4_FS_XATTR
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 ext4 filesystem.
If you are not using a security module that requires using
extended attributes for file security labels, say N.
config EXT4_DEBUG
bool "EXT4 debugging support"
depends on EXT4_FS
Enables run-time debugging support for the ext4 filesystem.
If you select Y here, then you will be able to turn on debugging
with a command such as "echo 1 > /sys/kernel/debug/ext4/mballoc-debug"