16da0b38fSAlexey Dobriyanconfig EXT4_FS 26da0b38fSAlexey Dobriyan tristate "The Extended 4 (ext4) filesystem" 36da0b38fSAlexey Dobriyan select JBD2 46da0b38fSAlexey Dobriyan select CRC16 56da0b38fSAlexey Dobriyan help 66da0b38fSAlexey Dobriyan This is the next generation of the ext3 filesystem. 76da0b38fSAlexey Dobriyan 86da0b38fSAlexey Dobriyan Unlike the change from ext2 filesystem to ext3 filesystem, 96da0b38fSAlexey Dobriyan the on-disk format of ext4 is not forwards compatible with 106da0b38fSAlexey Dobriyan ext3; it is based on extent maps and it supports 48-bit 116da0b38fSAlexey Dobriyan physical block numbers. The ext4 filesystem also supports delayed 126da0b38fSAlexey Dobriyan allocation, persistent preallocation, high resolution time stamps, 136da0b38fSAlexey Dobriyan and a number of other features to improve performance and speed 146da0b38fSAlexey Dobriyan up fsck time. For more information, please see the web pages at 156da0b38fSAlexey Dobriyan http://ext4.wiki.kernel.org. 166da0b38fSAlexey Dobriyan 176da0b38fSAlexey Dobriyan The ext4 filesystem will support mounting an ext3 186da0b38fSAlexey Dobriyan filesystem; while there will be some performance gains from 196da0b38fSAlexey Dobriyan the delayed allocation and inode table readahead, the best 206da0b38fSAlexey Dobriyan performance gains will require enabling ext4 features in the 21692105b8SMatt LaPlante filesystem, or formatting a new filesystem as an ext4 226da0b38fSAlexey Dobriyan filesystem initially. 236da0b38fSAlexey Dobriyan 246da0b38fSAlexey Dobriyan To compile this file system support as a module, choose M here. The 256da0b38fSAlexey Dobriyan module will be called ext4. 266da0b38fSAlexey Dobriyan 276da0b38fSAlexey Dobriyan If unsure, say N. 286da0b38fSAlexey Dobriyan 2924b58424STheodore Ts'oconfig EXT4_USE_FOR_EXT23 3024b58424STheodore Ts'o bool "Use ext4 for ext2/ext3 file systems" 31*a214238dSTheodore Ts'o depends on EXT3_FS=n || EXT2_FS=n 3224b58424STheodore Ts'o default y 3324b58424STheodore Ts'o help 3424b58424STheodore Ts'o Allow the ext4 file system driver code to be used for ext2 or 3524b58424STheodore Ts'o ext3 file system mounts. This allows users to reduce their 3624b58424STheodore Ts'o compiled kernel size by using one file system driver for 3724b58424STheodore Ts'o ext2, ext3, and ext4 file systems. 3824b58424STheodore Ts'o 396da0b38fSAlexey Dobriyanconfig EXT4_FS_XATTR 406da0b38fSAlexey Dobriyan bool "Ext4 extended attributes" 416da0b38fSAlexey Dobriyan depends on EXT4_FS 426da0b38fSAlexey Dobriyan default y 436da0b38fSAlexey Dobriyan help 446da0b38fSAlexey Dobriyan Extended attributes are name:value pairs associated with inodes by 456da0b38fSAlexey Dobriyan the kernel or by users (see the attr(5) manual page, or visit 466da0b38fSAlexey Dobriyan <http://acl.bestbits.at/> for details). 476da0b38fSAlexey Dobriyan 486da0b38fSAlexey Dobriyan If unsure, say N. 496da0b38fSAlexey Dobriyan 506da0b38fSAlexey Dobriyan You need this for POSIX ACL support on ext4. 516da0b38fSAlexey Dobriyan 526da0b38fSAlexey Dobriyanconfig EXT4_FS_POSIX_ACL 536da0b38fSAlexey Dobriyan bool "Ext4 POSIX Access Control Lists" 546da0b38fSAlexey Dobriyan depends on EXT4_FS_XATTR 556da0b38fSAlexey Dobriyan select FS_POSIX_ACL 566da0b38fSAlexey Dobriyan help 576da0b38fSAlexey Dobriyan POSIX Access Control Lists (ACLs) support permissions for users and 586da0b38fSAlexey Dobriyan groups beyond the owner/group/world scheme. 596da0b38fSAlexey Dobriyan 606da0b38fSAlexey Dobriyan To learn more about Access Control Lists, visit the POSIX ACLs for 616da0b38fSAlexey Dobriyan Linux website <http://acl.bestbits.at/>. 626da0b38fSAlexey Dobriyan 636da0b38fSAlexey Dobriyan If you don't know what Access Control Lists are, say N 646da0b38fSAlexey Dobriyan 656da0b38fSAlexey Dobriyanconfig EXT4_FS_SECURITY 666da0b38fSAlexey Dobriyan bool "Ext4 Security Labels" 676da0b38fSAlexey Dobriyan depends on EXT4_FS_XATTR 686da0b38fSAlexey Dobriyan help 696da0b38fSAlexey Dobriyan Security labels support alternative access control models 706da0b38fSAlexey Dobriyan implemented by security modules like SELinux. This option 716da0b38fSAlexey Dobriyan enables an extended attribute handler for file security 726da0b38fSAlexey Dobriyan labels in the ext4 filesystem. 736da0b38fSAlexey Dobriyan 746da0b38fSAlexey Dobriyan If you are not using a security module that requires using 756da0b38fSAlexey Dobriyan extended attributes for file security labels, say N. 766ba495e9STheodore Ts'o 776ba495e9STheodore Ts'oconfig EXT4_DEBUG 786ba495e9STheodore Ts'o bool "EXT4 debugging support" 796ba495e9STheodore Ts'o depends on EXT4_FS 806ba495e9STheodore Ts'o help 816ba495e9STheodore Ts'o Enables run-time debugging support for the ext4 filesystem. 826ba495e9STheodore Ts'o 836ba495e9STheodore Ts'o If you select Y here, then you will be able to turn on debugging 846ba495e9STheodore Ts'o with a command such as "echo 1 > /sys/kernel/debug/ext4/mballoc-debug" 85