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. After many original
ideas, approaches and improvements, it becomes totally
different from Unionfs while keeping the basic features.
See Unionfs for the basic features.
if AUFS
comment "These options are for 2.6.27-3-generic"
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 an 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 an 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 an 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 an 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 an impact to performance.
endchoice
config AUFS_STAT
bool "Use <sysfs>/fs/aufs/stat"
depends on SYSFS
help
Shows some statistic data via <sysfs>/fs/aufs/stat.
See detail in aufs.5.
comment "SYSFS and AUFS_STAT are disabled"
depends on SYSFS = n
config AUFS_HINOTIFY
bool "Use inotify to detect actions on a branch"
depends on INOTIFY
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=inotify' mount option.
It will have a negative impact to the performance.
See detail in aufs.5.
comment "INOTIFY and AUFS_HINOTIFY are disabled"
depends on INOTIFY = n
config AUFS_EXPORT
bool "NFS-exportable aufs"
depends on (AUFS = y && EXPORTFS = y) || (AUFS = m && EXPORTFS)
help
If you want to export your mounted aufs, then enable this
option. There are several requirements to export aufs.
See detail in aufs.5.
comment "EXPORTFS and AUFS_EXPORT are disabled"
depends on EXPORTFS = n
comment "AUFS_EXPORT is disabled since EXPORTFS is a module but AUFS"
depends on EXPORTFS = m && AUFS = y
config AUFS_INO_T_64
bool
depends on 64BIT && !(ALPHA || S390)
default y
config AUFS_ROBR
bool "Aufs as an readonly branch of another aufs mount"
help
If you want make your aufs to be a part of another aufs, then
enable this option. In other words, you can specify your aufs
path in 'br:' mount option for another aufs, but cannot
specify 'rw' as the branch permission.
It will have a negative impact to the performance.
See detail in aufs.5.
config AUFS_DLGT
bool "Delegate the internal branch access the kernel thread"
help
If you want aufs to delegate
the internal access to the branches which is made by aufs, to
the kernel thread, in order to hide the access issued by your
application from your LSM or something or make your
application to be traced strictly by the task I/O accounting,
then enable this option and use 'dlgt' mount option.
It will have a negative impact to the performance.
See detail in aufs.5.
config AUFS_HIN_OR_DLGT
bool
depends on AUFS_HINOTIFY || AUFS_DLGT
default y
help
Automatic configuration for internal use.
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_RR_SQUASHFS
bool "Make squashfs branch RR (real readonly) by default"
default y
help
If you use squashfs or LZMA patched squashfs as an aufs branch
and want to set '=rr' to it by default, then enable this
configuration.
'rr' stands for real readonly and it optimizes some aspects of
'ro.'
See detail in aufs.5.
config AUFS_SEC_PERM_PATCH
bool "sec_perm-2.6.24.patch was applied or not"
depends on AUFS = m
depends on SECURITY
help
If you build aufs as a module and enabled CONFIG_SECURITY,
then you need to apply the patch
'CVS_TREE/aufs/patch/sec_perm-2.6.24.patch' to your kernel
source, and enable this configuration.
The sec_perm-2.6.24.patch exports a kernel function
security_inode_permission() to modules.
comment "SECURITY and AUFS_SEC_PERM_PATCH are disabled"
depends on SECURITY = n
config AUFS_SPLICE_PATCH
bool "splice.patch for sendfile(2) and splice(2)"
help
If you use 'loopback mount' on a fs-image file, or use
splice(2) or sendfile(2) systemcall in aufs, then you need to
apply the patch 'CVS_TREE/aufs/patch/splice.patch' to your
kernel source, and enable this configuration.
The splice.patch makes the kernel function do_splice_to/from()
global and exports them to modules.
config AUFS_PUT_FILP_PATCH
bool "put_filp.patch for NFS branch"
depends on AUFS = m
depends on NFS_FS
help
If you build aufs as a module and use mounted NFS as an aufs
branch filesystem, then you need to apply the patch
'CVS_TREE/aufs/patch/put_filp.patch' to your kernel source,
and enable this configuration.
The put_filp.patch exports a kernel function put_filp() to
modules.
comment "NFS_FS and AUFS_PUT_FILP_PATCH are disabled"
depends on NFS_FS = n
config AUFS_LHASH_PATCH
bool "lhash.patch for NFS branch"
depends on NFS_FS
help
If you use mounted NFS as an aufs branch filesystem, then you
need to apply the patch 'CVS_TREE/aufs/patch/lhash.patch' (or
lhash-2.6.22.patch for linux-2.6.22 and later) to your kernel
source, and enable this configuration.
The patch file makes the kernel function __lookup_hash() global
and exports it to modules.
comment "NFS_FS and AUFS_LHASH_PATCH are disabled"
depends on NFS_FS = n
config AUFS_BR_NFS
bool
depends on NFS_FS
default n if (!AUFS_LHASH_PATCH || !(AUFS = y || AUFS_PUT_FILP_PATCH))
default y
help
Automatic configuration for internal use.
When aufs supports NFS branch, enabled automatically.
config AUFS_BR_XFS
bool
depends on XFS_FS
default y
help
Automatic configuration for internal use.
When aufs supports XFS branch, enabled automatically.
config AUFS_FSYNC_SUPER_PATCH
bool "fsync_super-2.6.xx.patch was applied or not"
depends on AUFS = m
help
If you build aufs as a module and want to flush everything for
branch filesystems which are not marked as 'rr' nor 'rr+wh' at
umount or remount time, then you need to apply the patch
'CVS_TREE/aufs/patch/fsync_super-2.6.16.patch' or
'...-2.6.19.patch' to your kernel source, and enable this
configuration.
It may be helpful at shutdown time in case of your aufs is a
root filesystem. But this behaviour will not guarantee the
consistency of branch filesystems. To guarantee it, try the
approach described in the aufs manual, and do not forget
installing auplink script.
The fsync_super-2.6.xx.patch does nothing but exports a kernel
function fsync_super() to modules.
config AUFS_DENY_WRITE_ACCESS_PATCH
bool "deny_write_access.patch was applied or not"
depends on AUFS = m
help
A security enhancement to deny writing to a running executable
which exists on an aufs branch filesystem and executed through
aufs. If you applied
'CVS_TREE/aufs/patch/deny_write_access.patch' to your kernel
and you are compiling aufs as a module, then enable this
option.
The write_deny_access.patch does nothing but export the
function.
config AUFS_WORKAROUND_FUSE
bool "Special handling for FUSE-based filesystem"
depends on FUSE_FS
help
A FUSE-based filesystem may not initialize its inode
attributes and the FUSE developer thinks the inode attributes
in a positive dentry which is returned by VFS lookup operation
are not reliable.
If you use a FUSE-based filesystem as an aufs branch, and it
customizes the inode attribute on it without overriding
fuse_lowlevel_ops.lookup, probably you need to enable this
configuration.
If you enable this configuration, aufs calls getattr operation
in every lookup and revalidate operation for the FUSE-based
filesystem branch.
It will have a negative impact to the performance even if you do
not use a FUSE-based filesystem branch.
config AUFS_HIN_OR_FUSE
bool
depends on AUFS_HINOTIFY || AUFS_WORKAROUND_FUSE
default y
help
Automatic configuration for internal use.
config AUFS_DEBUG
bool "Debug aufs"
default y
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.
config AUFS_COMPAT
bool "Compatibility with Unionfs (obsolete)"
help
This makes aufs compatible with unionfs-style mount options and some
behaviours.
The dirs= mount option and =nfsro branch permission flag are always
interpreted as br: mount option and =ro flag respectively. The
'debug', 'delete' and 'imap' mount options are ignored.
If you disable this option, you will get,
- aufs issues a warning about the ignored mount options
- the default branch permission flag is set. RW for the first branch,
and RO for the rests.
- the name of a internal file which represents the directory is
'opaque', becomes '.wh..wh..opq'
- the 'diropq=w' mount option is set by default
config AUFS_UNIONFS22_PATCH
bool "Unionfs-2.2 or later patch is applied or not (obsolete)"
help
Unionfs version 2.2 (and later) patch introduces some changes in VFS layer which has an impact to aufs. If you have applied such patch to your kernel, you need to enable this configuration even if you disabled CONFIG_UNIONFS.
config AUFS_UNIONFS23_PATCH
bool "Unionfs-2.3 or later patch is applied or not (obsolete)"
select AUFS_SPLICE_PATCH
select AUFS_UNIONFS22_PATCH
help
Unionfs version 2.3 (and later) patch introduces some changes in VFS layer which has an impact to aufs. If you have applied such patch to your kernel, you need to enable this configuration even if you disabled CONFIG_UNIONFS.
