Current File : //usr/src/linux-headers-5.15.0-125-generic/fs/aufs/Kconfig
# 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
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
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