1config EXT4_FS 2 tristate "The Extended 4 (ext4) filesystem" 3 select JBD2 4 select CRC16 5 help 6 This is the next generation of the ext3 filesystem. 7 8 Unlike the change from ext2 filesystem to ext3 filesystem, 9 the on-disk format of ext4 is not forwards compatible with 10 ext3; it is based on extent maps and it supports 48-bit 11 physical block numbers. The ext4 filesystem also supports delayed 12 allocation, persistent preallocation, high resolution time stamps, 13 and a number of other features to improve performance and speed 14 up fsck time. For more information, please see the web pages at 15 http://ext4.wiki.kernel.org. 16 17 The ext4 filesystem will support mounting an ext3 18 filesystem; while there will be some performance gains from 19 the delayed allocation and inode table readahead, the best 20 performance gains will require enabling ext4 features in the 21 filesystem, or formatting a new filesystem as an ext4 22 filesystem initially. 23 24 To compile this file system support as a module, choose M here. The 25 module will be called ext4. 26 27 If unsure, say N. 28 29config EXT4_USE_FOR_EXT23 30 bool "Use ext4 for ext2/ext3 file systems" 31 depends on EXT3_FS=n || EXT2_FS=n 32 default y 33 help 34 Allow the ext4 file system driver code to be used for ext2 or 35 ext3 file system mounts. This allows users to reduce their 36 compiled kernel size by using one file system driver for 37 ext2, ext3, and ext4 file systems. 38 39config EXT4_FS_XATTR 40 bool "Ext4 extended attributes" 41 depends on EXT4_FS 42 default y 43 help 44 Extended attributes are name:value pairs associated with inodes by 45 the kernel or by users (see the attr(5) manual page, or visit 46 <http://acl.bestbits.at/> for details). 47 48 If unsure, say N. 49 50 You need this for POSIX ACL support on ext4. 51 52config EXT4_FS_POSIX_ACL 53 bool "Ext4 POSIX Access Control Lists" 54 depends on EXT4_FS_XATTR 55 select FS_POSIX_ACL 56 help 57 POSIX Access Control Lists (ACLs) support permissions for users and 58 groups beyond the owner/group/world scheme. 59 60 To learn more about Access Control Lists, visit the POSIX ACLs for 61 Linux website <http://acl.bestbits.at/>. 62 63 If you don't know what Access Control Lists are, say N 64 65config EXT4_FS_SECURITY 66 bool "Ext4 Security Labels" 67 depends on EXT4_FS_XATTR 68 help 69 Security labels support alternative access control models 70 implemented by security modules like SELinux. This option 71 enables an extended attribute handler for file security 72 labels in the ext4 filesystem. 73 74 If you are not using a security module that requires using 75 extended attributes for file security labels, say N. 76 77config EXT4_DEBUG 78 bool "EXT4 debugging support" 79 depends on EXT4_FS 80 help 81 Enables run-time debugging support for the ext4 filesystem. 82 83 If you select Y here, then you will be able to turn on debugging 84 with a command such as "echo 1 > /sys/kernel/debug/ext4/mballoc-debug" 85