Commit 93fa58cb authored by Eric Van Hensbergen's avatar Eric Van Hensbergen Committed by Linus Torvalds

[PATCH] v9fs: Documentation, Makefiles, Configuration


V9FS is a distributed file system for Linux which provides an
implementation of the Plan 9 resource sharing protocol 9P.  It can be
used to share all sorts of resources: static files, synthetic file servers
(such as /proc or /sys), devices, and application file servers (such as


Plan 9 ( is a research operating
system and associated applications suite developed by the Computing
Science Research Center of AT&T Bell Laboratories (now a part of
Lucent Technologies), the same group that developed UNIX , C, and C++.
Plan 9 was initially released in 1993 to universities, and then made
generally available in 1995. Its core operating systems code laid the
foundation for the Inferno Operating System released as a product by
Lucent Bell-Labs in 1997. The Inferno venture was the only commercial
embodiment of Plan 9 and is currently maintained as a product by Vita
Nuova ( After updated releases in 2000 and
2002, Plan 9 was open-sourced under the OSI approved Lucent Public
License in 2003.

The Plan 9 project was started by Ken Thompson and Rob Pike in 1985.
Their intent was to explore potential solutions to some of the
shortcomings of UNIX in the face of the widespread use of high-speed
networks to connect machines. In UNIX, networking was an afterthought
and UNIX clusters became little more than a network of stand-alone
systems. Plan 9 was designed from first principles as a seamless
distributed system with integrated secure network resource sharing.
Applications and services were architected in such a way as to allow
for implicit distribution across a cluster of systems. Configuring an
environment to use remote application components or services in place
of their local equivalent could be achieved with a few simple command
line instructions. For the most part, application implementations
operated independent of the location of their actual resources.

Commercial operating systems haven't changed much in the 20 years
since Plan 9 was conceived. Network and distributed systems support is
provided by a patchwork of middle-ware, with an endless number of
packages supplying pieces of the puzzle. Matters are complicated by
the use of different complicated protocols for individual services,
and separate implementations for kernel and application resources.
The V9FS project ( is an attempt to bring
Plan 9's unified approach to resource sharing to Linux and other
operating systems via support for the 9P2000 resource sharing


V9FS was originally developed by Ron Minnich and Maya Gokhale at Los
Alamos National Labs (LANL) in 1997.  In November of 2001, Greg Watson
setup a SourceForge project as a public repository for the code which
supported the Linux 2.4 kernel.

About a year ago, I picked up the initial attempt Ron Minnich had
made to provide 2.6 support and got the code integrated into a 2.6.5
kernel.   I then went through a line-for-line re-write attempting to
clean-up the code while more closely following the Linux Kernel style
guidelines.  I co-authored a paper with Ron Minnich on the V9FS Linux
support including performance comparisons to NFSv3 using Bonnie and
PostMark - this paper appeared at the USENIX/FREENIX 2005
conference in April 2005:
( ).


Our 2.6 kernel support is stabilizing and we'd like to begin pursuing
its integration into the official kernel tree.  We would appreciate any
review, comments, critiques, and additions from this community and are
actively seeking people to join our project and help us produce
something that would be acceptable and useful to the Linux community.


The code is reasonably stable, although there are no doubt corner cases
our regression tests haven't discovered yet.  It is in regular use by several
of the developers and has been tested on x86 and PowerPC
(32-bit and 64-bit) in both small and large (LANL cluster) deployments.
Our current regression tests include fsx, bonnie, and postmark.

It was our intention to keep things as simple as possible for this
release -- trying to focus on correctness within the core of the
protocol support versus a rich set of features.  For example: a more
complete security model and cache layer are in the road map, but
excluded from this release.   Additionally, we have removed support for
mmap operations at Al Viro's request.


Detailed performance numbers and analysis are included in the FREENIX
paper, but we show comparable performance to NFSv3 for large file
operations based on the Bonnie benchmark, and superior performance for
many small file operations based on the PostMark benchmark.   Somewhat
preliminary graphs (from the FREENIX paper) are available


The source code is available in a few different forms:

Git: rsync:// (webgit:
9P: tcp!!6564

The user-level server is available from either the Plan 9 distribution
or from
Other support applications are still being developed, but preliminary
version can be downloaded from sourceforge.

Documentation on the protocol has historically been the Plan 9 Man
pages (, but there is
an effort under way to write a more complete Internet-Draft style
specification (

There are a couple of mailing lists supporting v9fs, but the most used
is -- please direct/cc your
comments there so the other v9fs contibutors can participate in the
conversation.  There is also an IRC channel: irc://

This part of the patch contains Documentation, Makefiles, and configuration
file changes.
Signed-off-by: default avatarEric Van Hensbergen <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 28225418
V9FS: 9P2000 for Linux
v9fs is a Unix implementation of the Plan 9 9p remote filesystem protocol.
This software was originally developed by Ron Minnich <>
and Maya Gokhale <>. Additional development by Greg Watson
<> and most recently Eric Van Hensbergen
<> and Latchesar Ionkov <>.
For remote file server:
mount -t 9P /mnt/9
For Plan 9 From User Space applications (
mount -t 9P `namespace`/acme /mnt/9 -o proto=unix,name=$USER
proto=name select an alternative transport. Valid options are
unix - specifying a named pipe mount point
tcp - specifying a normal TCP/IP connection
fd - used passed file descriptors for connection
(see rfdno and wfdno)
name=name user name to attempt mount as on the remote server. The
server may override or ignore this value. Certain user
names may require authentication.
aname=name aname specifies the file tree to access when the server is
offering several exported file systems.
debug=n specifies debug level. The debug level is a bitmask.
0x01 = display verbose error messages
0x02 = developer debug (DEBUG_CURRENT)
0x04 = display 9P trace
0x08 = display VFS trace
0x10 = display Marshalling debug
0x20 = display RPC debug
0x40 = display transport debug
0x80 = display allocation debug
rfdno=n the file descriptor for reading with proto=fd
wfdno=n the file descriptor for writing with proto=fd
maxdata=n the number of bytes to use for 9P packet payload (msize)
port=n port to connect to on the remote server
timeout=n request timeouts (in ms) (default 60000ms)
noextend force legacy mode (no 9P2000.u semantics)
uid attempt to mount as a particular uid
gid attempt to mount with a particular gid
afid security channel - used by Plan 9 authentication protocols
nodevmap do not map special files - represent them as normal files.
This can be used to share devices/named pipes/sockets between
hosts. This functionality will be expanded in later versions.
The Linux version of the 9P server, along with some client-side utilities
can be found at (along with a CVS repository of the
development branch of this module). There are user and developer mailing
lists here, as well as a bug-tracker.
For more information on the Plan 9 Operating System check out
For information on Plan 9 from User Space (Plan 9 applications and libraries
ported to Linux/BSD/OSX/etc) check out
The 2.6 kernel support is working on PPC and x86.
......@@ -2684,6 +2684,17 @@ L:
S: Maintained
P: Eric Van Hensbergen
P: Ron Minnich
P: Latchesar Ionkov
S: Maintained
P: Mauro Carvalho Chehab
obj-$(CONFIG_9P_FS) := 9p2000.o
9p2000-objs := \
vfs_super.o \
vfs_inode.o \
vfs_file.o \
vfs_dir.o \
vfs_dentry.o \
error.o \
mux.o \
trans_fd.o \
trans_sock.o \
9p.o \
conv.o \
v9fs.o \
......@@ -1703,6 +1703,17 @@ config AFS_FS
config RXRPC
config 9P_FS
tristate "Plan 9 Resource Sharing Support (9P2000) (Experimental)"
If you say Y here, you will get experimental support for
Plan 9 resource sharing via the 9P2000 protocol.
See <> for more information.
If unsure, say N.
menu "Partition Types"
......@@ -94,6 +94,7 @@ obj-$(CONFIG_RELAYFS_FS) += relayfs/
obj-$(CONFIG_SUN_OPENPROMFS) += openpromfs/
obj-$(CONFIG_JFS_FS) += jfs/
obj-$(CONFIG_XFS_FS) += xfs/
obj-$(CONFIG_9P_FS) += 9p/
obj-$(CONFIG_AFS_FS) += afs/
obj-$(CONFIG_BEFS_FS) += befs/
obj-$(CONFIG_HOSTFS) += hostfs/
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