| 1 | # SPDX-License-Identifier: GPL-2.0-only |
| 2 | config EXT4_FS |
| 3 | tristate "The Extended 4 (ext4) filesystem" |
| 4 | select BUFFER_HEAD |
| 5 | select JBD2 |
| 6 | select CRC16 |
| 7 | select CRC32 |
| 8 | select FS_IOMAP |
| 9 | select FS_ENCRYPTION_ALGS if FS_ENCRYPTION |
| 10 | help |
| 11 | This is the next generation of the ext3 filesystem. |
| 12 | |
| 13 | Unlike the change from ext2 filesystem to ext3 filesystem, |
| 14 | the on-disk format of ext4 is not forwards compatible with |
| 15 | ext3; it is based on extent maps and it supports 48-bit |
| 16 | physical block numbers. The ext4 filesystem also supports delayed |
| 17 | allocation, persistent preallocation, high resolution time stamps, |
| 18 | and a number of other features to improve performance and speed |
| 19 | up fsck time. For more information, please see the web pages at |
| 20 | http://ext4.wiki.kernel.org. |
| 21 | |
| 22 | The ext4 filesystem supports mounting an ext3 filesystem; while there |
| 23 | are some performance gains from the delayed allocation and inode |
| 24 | table readahead, the best performance gains require enabling ext4 |
| 25 | features in the filesystem using tune2fs, or formatting a new |
| 26 | filesystem as an ext4 filesystem initially. Without explicit enabling |
| 27 | of ext4 features, the on disk filesystem format stays fully backward |
| 28 | compatible. |
| 29 | |
| 30 | To compile this file system support as a module, choose M here. The |
| 31 | module will be called ext4. |
| 32 | |
| 33 | If unsure, say N. |
| 34 | |
| 35 | config EXT4_USE_FOR_EXT2 |
| 36 | bool "Use ext4 for ext2 file systems" |
| 37 | depends on EXT4_FS |
| 38 | depends on EXT2_FS=n |
| 39 | default y |
| 40 | help |
| 41 | Allow the ext4 file system driver code to be used for ext2 |
| 42 | file system mounts. This allows users to reduce their |
| 43 | compiled kernel size by using one file system driver for |
| 44 | ext2, ext3, and ext4 file systems. |
| 45 | |
| 46 | config EXT4_FS_POSIX_ACL |
| 47 | bool "Ext4 POSIX Access Control Lists" |
| 48 | depends on EXT4_FS |
| 49 | select FS_POSIX_ACL |
| 50 | help |
| 51 | POSIX Access Control Lists (ACLs) support permissions for users and |
| 52 | groups beyond the owner/group/world scheme. |
| 53 | |
| 54 | If you don't know what Access Control Lists are, say N |
| 55 | |
| 56 | config EXT4_FS_SECURITY |
| 57 | bool "Ext4 Security Labels" |
| 58 | depends on EXT4_FS |
| 59 | help |
| 60 | Security labels support alternative access control models |
| 61 | implemented by security modules like SELinux. This option |
| 62 | enables an extended attribute handler for file security |
| 63 | labels in the ext4 filesystem. |
| 64 | |
| 65 | If you are not using a security module that requires using |
| 66 | extended attributes for file security labels, say N. |
| 67 | |
| 68 | config EXT4_DEBUG |
| 69 | bool "Ext4 debugging support" |
| 70 | depends on EXT4_FS |
| 71 | help |
| 72 | Enables run-time debugging support for the ext4 filesystem. |
| 73 | |
| 74 | If you select Y here, then you will be able to turn on debugging |
| 75 | using dynamic debug control for mb_debug() / ext_debug() msgs. |
| 76 | |
| 77 | config EXT4_KUNIT_TESTS |
| 78 | tristate "KUnit tests for ext4" if !KUNIT_ALL_TESTS |
| 79 | depends on EXT4_FS && KUNIT |
| 80 | default KUNIT_ALL_TESTS |
| 81 | help |
| 82 | This builds the ext4 KUnit tests. |
| 83 | |
| 84 | KUnit tests run during boot and output the results to the debug log |
| 85 | in TAP format (https://testanything.org/). Only useful for kernel devs |
| 86 | running KUnit test harness and are not for inclusion into a production |
| 87 | build. |
| 88 | |
| 89 | For more information on KUnit and unit tests in general please refer |
| 90 | to the KUnit documentation in Documentation/dev-tools/kunit/. |
| 91 | |
| 92 | If unsure, say N. |