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- selectable permission flags for ro branch, whether whiteout can
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- support <sysfs>/fs/aufs.
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- support multiple writable branches, some policies to select one
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among multiple writable branches.
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- a new semantics for link(2) and rename(2) to support multiple
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- a delegation of the internal branch access to support task I/O
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accounting, which also supports Linux Security Modules (LSM) mainly
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- nested mount, i.e. aufs as readonly no-whiteout branch of another aufs.
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- and more... see aufs manual in detail
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Aufs is in still development stage, especially,,,
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Aufs is in still development stage, especially:
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- pseudo hardlink (hardlink over branches)
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- allow a direct access manually to a file on branch, e.g. bypassing aufs.
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including NFS or remote filesystem branch.
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- refine xino and revalidate
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- pseudo-link in NFS-exporting
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- a delegation of the internal branch access to support task I/O
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accounting, which also supports Linux Security Modules (LSM) mainly
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- nested mount, i.e. aufs as readonly no-whiteout branch of another aufs.
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- reorder the branch index without del/re-add.
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- permanent xino files
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- an option for refreshing the opened files after add/del branches
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- 'move' policy for copy-up between two writable branches, after
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- ioctl to manipulate file between branches.
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- sample for kvm, xen, vmware and openvz? If a directory can be
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sharable between several Guest-OSes, to share readonly aufs branches
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- remount option copy/move between two branches. (unnecessary?)
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- O_DIRECT (unnecessary?)
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- light version, without branch manipulation. (unnecessary?)
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- SMP, because I don't have such machine. But several users reported
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aufs is working fine on SMP machines.
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- 64bit environment, because I don't have such machine.
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90
- copyup in userspace
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- inotify in userspace
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- disk quota (unnecessary?)
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$ cd aufs.wcvs/aufs
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$ cvs diff -D20061212 -D20061219
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Usually I am updating CVS tree on every Monday.
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115
I always try putting the stable version in CVS, so you can try CVS
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116
instead of SourceForge File Release. And every changes are summarized
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and reported to aufs-users at lists.sourceforge.net ML. It is recommended to
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and reported to aufs-users at lists.sourceforge.net ML. I'd like to
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recommend you to join this ML.
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3. Configuration and Compilation
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122
----------------------------------------
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Aufs is being developed and tested on linux-2.6.16 and later
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(But I am planning to shift to the 'linux-2.6.18 and later').
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Aufs is being developed and tested on linux-2.6.16 and later.
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You need the correct environment to build a kernel module. Generally
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it is an environment which your kernel was built.
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If you are unsure that you got the correct environment, then I
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recommend you to built your kernel by yourself. If it succeeds, you've
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got the correct environment.
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Currently aufs configuration is written in ./Kconfig.in. You can build the
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real ./fs/aufs/Kconfig file by 'make.' And follow the instructions which will
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be produced. The built ./fs/aufs/Kconfig depends upon the kernel version.
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Currently aufs configuration is written in ./Kconfig.in. You can
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generate the real ./fs/aufs/Kconfig file by make(1). And follow the
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instructions which will be produced. The built ./fs/aufs/Kconfig
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depends upon the kernel version.
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Before you build ./fs/aufs/Kconfig, you need to configure your kernel,
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since this build refers to linux/include/version.h.
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136
$ make -f local.mk kconfig
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The local.mk searches your kernel build path by
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139
KDIR = /lib/modules/$(shell uname -r)/build
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If you are cross-compiling the aufs module, try
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$ make KDIR=/your/kernel/build/path -f local.mk kconfig
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If you compile aufs statically, the built Kconfig will help you.
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If you link aufs statically, the generated Kconfig will help you.
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144
Also you can use ./local.mk to compile aufs as a module by simply,
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145
$ make -f local.mk
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configuration for your aufs module.
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If you don't want to change the ./local.mk, then create a new file
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./priv_def.mk and write the definitions your aufs configuration. The
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./local.mk includes ./priv_def.mk it it exists.
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./local.mk includes ./priv_def.mk if it exists.
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When you configure aufs by modifying ./local.mk (or ./priv_dev.mk),
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leave it blank/unset when you disable an aufs configuration, instead
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There is a contributed Makefile for aufs users. You might want to try
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http://sourceforge.net/mailarchive/forum.php?thread_name=9c4865a10707241831r189f9646n5f2c4a9c303797d1%40mail.gmail.com&forum_name=aufs-users
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and see the attachment.
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Currently, CONFIG_DEBUG_PROVE_LOCKING (in linux kernel) is not
146
supported since MAX_LOCKDEP_SUBCLASSES is too low for a stackable
165
supported since MAX_LOCKDEP_SUBCLASSES is too small for a stackable
147
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filesystem. I am trying reducing the depth of lock subclasses.
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Until then, you need to increase the value of MAX_LOCKDEP_SUBCLASSES
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macro in include/linux/lockdep.h, for example, 16UL, when you enable
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CONFIG_DEBUG_PROVE_LOCKING.
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When you test the performance, it is recommended to disable
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CONFIG_AUFS_DEBUG. It is enabled by default for the feature test.
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Since aufs supports several versions of linux kernel, it uses the
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#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 18)
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On the other hand, some distributions modify their kernel by their own
178
patches. For example, just a piece of code is brought from v2.6.18 and
179
merged into a distribution kernel which calls itself as v2.6.17.
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Finally, the conditions in aufs will not work correctly.
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You may or may not find them when you compile aufs.
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You need to modify aufs source code for 'custom-version' kernel
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(cf. patch/ubuntu-edgy.patch).
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There are several patches for linux kernel, in order to use aufs.
188
All of them are not necessary essentially, but in some cases you need
189
them. It is up to your environment and aufs usage.
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All these patches are just for exporting a kernel internal function to
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modules. If the function was already declared as extern and you link
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aufs statically to your kernel, then you don't need such patch. If the
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function was not extern and you want the feature, you need to apply
195
When you apply a patch, you need to enable the corresponding aufs
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All these patches are under CVS_TREE/aufs/patch.
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- sec_perm-2.6.24.patch
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For linux-2.6.24 and later.
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When you compile aufs as a module and enable CONFIG_SECURITY, this
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- splice-2.6.23.patch
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For linux-2.6.23 and later.
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When you use splice(2) or loopback-mount an fs-image file in aufs,
206
this patch is required. Aufs doesn't support splice(2) in
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linux-2.6.22 and earlier.
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- sysfs_get_dentry.patch
209
For linux-2.6.23 and later.
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If you want to see the file size under /sys/fs/aufs, apply this
211
patch. I am afraid most people never care the size of such file.
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The size shows the size of a memory allocated in kernel space.
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If you write something to the file under /sys/fs/aufs, the file size
214
will be zero and the memory will be freed.
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For linux-2.6.19 and later.
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When you compile aufs as a module and use NFS as an aufs branch
218
filesystem, this patch is required.
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For linux-2.6.19 and later till linux-2.6.21.
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When you use NFS as an aufs branch filesystem, this patch is
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Same above, but this patch is for linux-2.6.22 only.
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- deny_write_access.patch
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For linux-2.6.17 and later.
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When you compile aufs as a module, applied this patch and enabled a
228
configuration, a minor security enhancement will be available at
230
You can omit this if you don't care the writing to a running
231
executable on a lower branch filesystem which was invoked through
234
For linux-2.6.22 and earlier.
235
When you compile aufs as a module and applied this patch, an
236
optimization inside aufs will be available at adding or deleting a
237
branch filesystem. You can omit this if you don't care the aufs
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Additionally, there are patches for aufs which will be necessary when
241
you use non-standard kernel modules or patches. Some of them have been
242
tested by several people, but not all.
243
See also the comments in the patches.
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- ubuntu-2.6.22-14.46.patch
246
(http://archive.ubuntu.com/ubuntu/pool/main/l/linux-source-2.6.22/
247
linux-source-2.6.22_2.6.22-14.46_all.deb) which is modifed a lot by
250
For Ubuntu Edgy kernel which calls itself as 2.6.17, while its
251
umount_begin() interface has arguments of 2.6.18.
253
For realtime patch (http://people.redhat.com/mingo/realtime-preempt).
255
For linux-vserver module (http://linux-vserver.org).
256
- openvz_028stab039.1.patch
257
For openvz module (http://openvz.org).
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261
----------------------------------------
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$ man -l ./aufs.5
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# install -m 500 -p mount.aufs umount.aufs auplink aulchown /sbin (recommended)
265
# echo FLUSH=ALL > /etc/default/auplink (recommended)
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# insmod ./aufs.ko
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$ mkdir /tmp/rw /tmp/aufs
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# mount -t aufs -o dirs=/tmp/rw:${HOME}=ro none /tmp/aufs
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If you are familiar with Unionfs Version 1.x series and want to use
271
unionctl(8), you can try the sample unionctl script under sample/
162
274
Here is another example.
164
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# mount -t aufs -o br:/tmp/rw:${HOME}=ro none /tmp/aufs
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