1*6da0b38fSAlexey Dobriyanconfig EXT4_FS 2*6da0b38fSAlexey Dobriyan tristate "The Extended 4 (ext4) filesystem" 3*6da0b38fSAlexey Dobriyan select JBD2 4*6da0b38fSAlexey Dobriyan select CRC16 5*6da0b38fSAlexey Dobriyan help 6*6da0b38fSAlexey Dobriyan This is the next generation of the ext3 filesystem. 7*6da0b38fSAlexey Dobriyan 8*6da0b38fSAlexey Dobriyan Unlike the change from ext2 filesystem to ext3 filesystem, 9*6da0b38fSAlexey Dobriyan the on-disk format of ext4 is not forwards compatible with 10*6da0b38fSAlexey Dobriyan ext3; it is based on extent maps and it supports 48-bit 11*6da0b38fSAlexey Dobriyan physical block numbers. The ext4 filesystem also supports delayed 12*6da0b38fSAlexey Dobriyan allocation, persistent preallocation, high resolution time stamps, 13*6da0b38fSAlexey Dobriyan and a number of other features to improve performance and speed 14*6da0b38fSAlexey Dobriyan up fsck time. For more information, please see the web pages at 15*6da0b38fSAlexey Dobriyan http://ext4.wiki.kernel.org. 16*6da0b38fSAlexey Dobriyan 17*6da0b38fSAlexey Dobriyan The ext4 filesystem will support mounting an ext3 18*6da0b38fSAlexey Dobriyan filesystem; while there will be some performance gains from 19*6da0b38fSAlexey Dobriyan the delayed allocation and inode table readahead, the best 20*6da0b38fSAlexey Dobriyan performance gains will require enabling ext4 features in the 21*6da0b38fSAlexey Dobriyan filesystem, or formating a new filesystem as an ext4 22*6da0b38fSAlexey Dobriyan filesystem initially. 23*6da0b38fSAlexey Dobriyan 24*6da0b38fSAlexey Dobriyan To compile this file system support as a module, choose M here. The 25*6da0b38fSAlexey Dobriyan module will be called ext4. 26*6da0b38fSAlexey Dobriyan 27*6da0b38fSAlexey Dobriyan If unsure, say N. 28*6da0b38fSAlexey Dobriyan 29*6da0b38fSAlexey Dobriyanconfig EXT4DEV_COMPAT 30*6da0b38fSAlexey Dobriyan bool "Enable ext4dev compatibility" 31*6da0b38fSAlexey Dobriyan depends on EXT4_FS 32*6da0b38fSAlexey Dobriyan help 33*6da0b38fSAlexey Dobriyan Starting with 2.6.28, the name of the ext4 filesystem was 34*6da0b38fSAlexey Dobriyan renamed from ext4dev to ext4. Unfortunately there are some 35*6da0b38fSAlexey Dobriyan legacy userspace programs (such as klibc's fstype) have 36*6da0b38fSAlexey Dobriyan "ext4dev" hardcoded. 37*6da0b38fSAlexey Dobriyan 38*6da0b38fSAlexey Dobriyan To enable backwards compatibility so that systems that are 39*6da0b38fSAlexey Dobriyan still expecting to mount ext4 filesystems using ext4dev, 40*6da0b38fSAlexey Dobriyan chose Y here. This feature will go away by 2.6.31, so 41*6da0b38fSAlexey Dobriyan please arrange to get your userspace programs fixed! 42*6da0b38fSAlexey Dobriyan 43*6da0b38fSAlexey Dobriyanconfig EXT4_FS_XATTR 44*6da0b38fSAlexey Dobriyan bool "Ext4 extended attributes" 45*6da0b38fSAlexey Dobriyan depends on EXT4_FS 46*6da0b38fSAlexey Dobriyan default y 47*6da0b38fSAlexey Dobriyan help 48*6da0b38fSAlexey Dobriyan Extended attributes are name:value pairs associated with inodes by 49*6da0b38fSAlexey Dobriyan the kernel or by users (see the attr(5) manual page, or visit 50*6da0b38fSAlexey Dobriyan <http://acl.bestbits.at/> for details). 51*6da0b38fSAlexey Dobriyan 52*6da0b38fSAlexey Dobriyan If unsure, say N. 53*6da0b38fSAlexey Dobriyan 54*6da0b38fSAlexey Dobriyan You need this for POSIX ACL support on ext4. 55*6da0b38fSAlexey Dobriyan 56*6da0b38fSAlexey Dobriyanconfig EXT4_FS_POSIX_ACL 57*6da0b38fSAlexey Dobriyan bool "Ext4 POSIX Access Control Lists" 58*6da0b38fSAlexey Dobriyan depends on EXT4_FS_XATTR 59*6da0b38fSAlexey Dobriyan select FS_POSIX_ACL 60*6da0b38fSAlexey Dobriyan help 61*6da0b38fSAlexey Dobriyan POSIX Access Control Lists (ACLs) support permissions for users and 62*6da0b38fSAlexey Dobriyan groups beyond the owner/group/world scheme. 63*6da0b38fSAlexey Dobriyan 64*6da0b38fSAlexey Dobriyan To learn more about Access Control Lists, visit the POSIX ACLs for 65*6da0b38fSAlexey Dobriyan Linux website <http://acl.bestbits.at/>. 66*6da0b38fSAlexey Dobriyan 67*6da0b38fSAlexey Dobriyan If you don't know what Access Control Lists are, say N 68*6da0b38fSAlexey Dobriyan 69*6da0b38fSAlexey Dobriyanconfig EXT4_FS_SECURITY 70*6da0b38fSAlexey Dobriyan bool "Ext4 Security Labels" 71*6da0b38fSAlexey Dobriyan depends on EXT4_FS_XATTR 72*6da0b38fSAlexey Dobriyan help 73*6da0b38fSAlexey Dobriyan Security labels support alternative access control models 74*6da0b38fSAlexey Dobriyan implemented by security modules like SELinux. This option 75*6da0b38fSAlexey Dobriyan enables an extended attribute handler for file security 76*6da0b38fSAlexey Dobriyan labels in the ext4 filesystem. 77*6da0b38fSAlexey Dobriyan 78*6da0b38fSAlexey Dobriyan If you are not using a security module that requires using 79*6da0b38fSAlexey Dobriyan extended attributes for file security labels, say N. 80