Files
linux/fs/ext4/Kconfig
Lukas Bulwahn d6ace46c82 ext4: remove obsolete EXT3 config options
In June 2015, commit c290ea01ab ("fs: Remove ext3 filesystem driver")
removed the historic ext3 filesystem support as ext3 partitions are fully
supported with the ext4 filesystem support. To simplify updating the kernel
build configuration, which had only EXT3 support but not EXT4 support
enabled, the three config options EXT3_{FS,FS_POSIX_ACL,FS_SECURITY} were
kept, instead of immediately removing them. The three options just enable
the corresponding EXT4 counterparts when configs from older kernel versions
are used to build on later kernel versions. This ensures that the kernels
from those kernel build configurations would then continue to have EXT4
enabled for supporting booting from ext3 and ext4 file systems, to avoid
potential unexpected surprises.

Given that the kernel build configuration has no backwards-compatibility
guarantee and this transition phase for such build configurations has been
in place for a decade, we can reasonably expect all such users to have
transitioned to use the EXT4 config options in their config files at this
point in time. With that in mind, the three EXT3 config options are
obsolete by now.

Remove the obsolete EXT3 config options.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2025-09-25 14:47:05 -04:00

93 lines
3.1 KiB
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# SPDX-License-Identifier: GPL-2.0-only
config EXT4_FS
tristate "The Extended 4 (ext4) filesystem"
select BUFFER_HEAD
select JBD2
select CRC16
select CRC32
select FS_IOMAP
select FS_ENCRYPTION_ALGS if FS_ENCRYPTION
help
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
http://ext4.wiki.kernel.org.
The ext4 filesystem supports mounting an ext3 filesystem; while there
are some performance gains from the delayed allocation and inode
table readahead, the best performance gains require enabling ext4
features in the filesystem using tune2fs, or formatting a new
filesystem as an ext4 filesystem initially. Without explicit enabling
of ext4 features, the on disk filesystem format stays fully backward
compatible.
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_EXT2
bool "Use ext4 for ext2 file systems"
depends on EXT4_FS
depends on EXT2_FS=n
default y
help
Allow the ext4 file system driver code to be used for ext2
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_POSIX_ACL
bool "Ext4 POSIX Access Control Lists"
depends on EXT4_FS
select FS_POSIX_ACL
help
POSIX Access Control Lists (ACLs) support permissions for users and
groups beyond the owner/group/world scheme.
If you don't know what Access Control Lists are, say N
config EXT4_FS_SECURITY
bool "Ext4 Security Labels"
depends on EXT4_FS
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 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
help
Enables run-time debugging support for the ext4 filesystem.
If you select Y here, then you will be able to turn on debugging
using dynamic debug control for mb_debug() / ext_debug() msgs.
config EXT4_KUNIT_TESTS
tristate "KUnit tests for ext4" if !KUNIT_ALL_TESTS
depends on EXT4_FS && KUNIT
default KUNIT_ALL_TESTS
help
This builds the ext4 KUnit tests.
KUnit tests run during boot and output the results to the debug log
in TAP format (https://testanything.org/). Only useful for kernel devs
running KUnit test harness and are not for inclusion into a production
build.
For more information on KUnit and unit tests in general please refer
to the KUnit documentation in Documentation/dev-tools/kunit/.
If unsure, say N.