config EXT4_FS tristate "The Extended 4 (ext4) filesystem" select JBD2 select CRC16 select CRYPTO select CRYPTO_CRC32C 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 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 help 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_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. 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 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_FS_ENCRYPTION bool "Ext4 Encryption" depends on EXT4_FS select CRYPTO_AES select CRYPTO_CBC select CRYPTO_ECB select CRYPTO_XTS select CRYPTO_CTS select CRYPTO_CTR select CRYPTO_SHA256 select KEYS select ENCRYPTED_KEYS help Enable encryption of ext4 files and directories. This feature is similar to ecryptfs, but it is more memory efficient since it avoids caching the encrypted and decrypted pages in the page cache. 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 with a command such as: echo 1 > /sys/module/ext4/parameters/mballoc_debug