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# SPDX-License-Identifier: GPL-2.0 config AUFS_FS tristate "Aufs (Advanced multi layered unification filesystem) support" help Aufs is a stackable unification filesystem such as Unionfs, which unifies several directories and provides a merged single directory. In the early days, aufs was entirely re-designed and re-implemented Unionfs Version 1.x series. Introducing many original ideas, approaches and improvements, it becomes totally different from Unionfs while keeping the basic features. if AUFS_FS choice prompt "Maximum number of branches" default AUFS_BRANCH_MAX_127 help Specifies the maximum number of branches (or member directories) in a single aufs. The larger value consumes more system resources and has a minor impact to performance. config AUFS_BRANCH_MAX_127 bool "127" help Specifies the maximum number of branches (or member directories) in a single aufs. The larger value consumes more system resources and has a minor impact to performance. config AUFS_BRANCH_MAX_511 bool "511" help Specifies the maximum number of branches (or member directories) in a single aufs. The larger value consumes more system resources and has a minor impact to performance. config AUFS_BRANCH_MAX_1023 bool "1023" help Specifies the maximum number of branches (or member directories) in a single aufs. The larger value consumes more system resources and has a minor impact to performance. config AUFS_BRANCH_MAX_32767 bool "32767" help Specifies the maximum number of branches (or member directories) in a single aufs. The larger value consumes more system resources and has a minor impact to performance. endchoice config AUFS_SBILIST bool depends on AUFS_MAGIC_SYSRQ || PROC_FS default y help Automatic configuration for internal use. When aufs supports Magic SysRq or /proc, enabled automatically. config AUFS_HNOTIFY bool "Detect direct branch access (bypassing aufs)" help If you want to modify files on branches directly, eg. bypassing aufs, and want aufs to detect the changes of them fully, then enable this option and use 'udba=notify' mount option. Currently there is only one available configuration, "fsnotify". It will have a negative impact to the performance. See detail in aufs.5. choice prompt "method" if AUFS_HNOTIFY default AUFS_HFSNOTIFY config AUFS_HFSNOTIFY bool "fsnotify" select FSNOTIFY endchoice config AUFS_EXPORT bool "NFS-exportable aufs" depends on EXPORTFS help If you want to export your mounted aufs via NFS, then enable this option. There are several requirements for this configuration. See detail in aufs.5. config AUFS_INO_T_64 bool depends on AUFS_EXPORT depends on 64BIT && !(ALPHA || S390) default y help Automatic configuration for internal use. /* typedef unsigned long/int __kernel_ino_t */ /* alpha and s390x are int */ config AUFS_XATTR bool "support for XATTR/EA (including Security Labels)" help If your branch fs supports XATTR/EA and you want to make them available in aufs too, then enable this opsion and specify the branch attributes for EA. See detail in aufs.5. config AUFS_FHSM bool "File-based Hierarchical Storage Management" help Hierarchical Storage Management (or HSM) is a well-known feature in the storage world. Aufs provides this feature as file-based. with multiple branches. These multiple branches are prioritized, ie. the topmost one should be the fastest drive and be used heavily. config AUFS_RDU bool "Readdir in userspace" help Aufs has two methods to provide a merged view for a directory, by a user-space library and by kernel-space natively. The latter is always enabled but sometimes large and slow. If you enable this option, install the library in aufs2-util package, and set some environment variables for your readdir(3), then the work will be handled in user-space which generally shows better performance in most cases. See detail in aufs.5. config AUFS_DIRREN bool "Workaround for rename(2)-ing a directory" help By default, aufs returns EXDEV error in renameing a dir who has his child on the lower branch, since it is a bad idea to issue rename(2) internally for every lower branch. But user may not accept this behaviour. So here is a workaround to allow such rename(2) and store some extra infromation on the writable branch. Obviously this costs high (and I don't like it). To use this feature, you need to enable this configuration AND to specify the mount option `dirren.' See details in aufs.5 and the design documents. config AUFS_SHWH bool "Show whiteouts" help If you want to make the whiteouts in aufs visible, then enable this option and specify 'shwh' mount option. Although it may sounds like philosophy or something, but in technically it simply shows the name of whiteout with keeping its behaviour. config AUFS_BR_RAMFS bool "Ramfs (initramfs/rootfs) as an aufs branch" help If you want to use ramfs as an aufs branch fs, then enable this option. Generally tmpfs is recommended. Aufs prohibited them to be a branch fs by default, because initramfs becomes unusable after switch_root or something generally. If you sets initramfs as an aufs branch and boot your system by switch_root, you will meet a problem easily since the files in initramfs may be inaccessible. Unless you are going to use ramfs as an aufs branch fs without switch_root or something, leave it N. config AUFS_BR_FUSE bool "Fuse fs as an aufs branch" depends on FUSE_FS select AUFS_POLL help If you want to use fuse-based userspace filesystem as an aufs branch fs, then enable this option. It implements the internal poll(2) operation which is implemented by fuse only (curretnly). config AUFS_POLL bool help Automatic configuration for internal use. config AUFS_BR_HFSPLUS bool "Hfsplus as an aufs branch" depends on HFSPLUS_FS default y help If you want to use hfsplus fs as an aufs branch fs, then enable this option. This option introduces a small overhead at copying-up a file on hfsplus. config AUFS_BDEV_LOOP bool depends on BLK_DEV_LOOP default y help Automatic configuration for internal use. Convert =[ym] into =y. config AUFS_DEBUG bool "Debug aufs" help Enable this to compile aufs internal debug code. It will have a negative impact to the performance. config AUFS_MAGIC_SYSRQ bool depends on AUFS_DEBUG && MAGIC_SYSRQ default y help Automatic configuration for internal use. When aufs supports Magic SysRq, enabled automatically. endif