[RFC][PATCH 0/7] v9fs: Plan 9 resource sharing protocol (2.0-rc7)

[ericvh@gmail.com]

This is part [0/7] of the v9fs-2.0-rc7 patch against Linux 2.6.

Hi everyone, we'd like to announce v2.0-rc7 of our 9P2000 file system 
driver support for Linux in order to solicit comments and criticism.

BACKGROUND

Plan 9 (http://plan9.bell-labs.com/plan9) 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 (http://www.vitanuova.com). 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 (http://v9fs.sourceforge.net) 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
protocol.

V9FS HISTORY

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:
( http://www.usenix.org/events/usenix05/tech/freenix/hensbergen.html ).

CALL FOR PARTICIPATION/REQUEST FOR COMMENTS

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.

STATUS

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.

PERFORMANCE

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
(http://v9fs.sourceforge.net/perf/index.html).

RESOURCES

The source code is available in a few different forms:

tarballs: http://v9fs.sf.net
CVSweb: http://cvs.sourceforge.net/viewcvs.py/v9fs/linux-9p/
CVS: :pserver:anonymous@cvs.sourceforge.net:/cvsroot/v9fs/linux-9p
Git: rsync://v9fs.graverobber.org/v9fs (webgit: http://v9fs.graverobber.org)
9P: tcp!v9fs.graverobber.org!6564

The user-level server is available from either the Plan 9 distribution
or from http://v9fs.sf.net
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 (http://plan9.bell-labs.com/sys/man/5/INDEX.html), but there is
an effort under way to write a more complete Internet-Draft style
specification (http://v9fs.sf.net/rfc).

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

THANKS

Thanks for your time in reading this message, I look forward to
hearing from all of you -- we are well aware that there is much work
to do, but I hope that with your help we can produce something that
everyone finds useful and valuable.

       -Eric Van Hensbergen
         V9FS Project


 ----------

====== 06/01/2005 - erichv ===
 * split dentry routines out to vfs_dentry to reduce vfs_inode size
 * some new error codes from ron

====== 05/31/2005 - ericvh ===
 * get rid of dynamic rpc struct allocation and associated slab
 * get rid of vestigial address_space_operations (from Pekka)
 * fix type name convention to Linux kernel standard (from Pekka)

====== 05/27/2005 - ericvh ====
 * remove potential slab leak in init_v9fs
 * modify QID to prevent inodes of 0 or 1

====== 05/25/2005 - ericvh ====
 * more LKML suggested cleanups
 * change packet and mistruct slab alloc to kmalloc

====== 05/24/2005 - ericvh ====
 * remove BUG() statements in OOM cases
 * clean up more bogus kfree checks
 * clean up error cases and redundant assignments in vfs_inode
 * change the way aname (remotename) is specified and allocated

====== 05/23/2005 - ericvh ====
 * release 2.0-rc6
 * Fix some style screwups

====== 05/20/2005 - ericvh ====
 * Fix multi-user bug reported by Ron & Ollie
 * change /usr/src/linux to KDIR in CVS makefile 
 * fix bogus copy_to_user error messages

====== 05/16/2005 - ericvh ====
 * release 2.0-rc5
 * Adrian Bunk style corrections
       - add statics where appropriate
       - remove unused procedures
       - pay attention to copy_from_user and copy_to_user return codes

====== 05/05/2005 - ericvh ====
 * additional cleanup of free null checks throughout code
 * fix slab leaks

====== 05/04/2005 - ericvh ====
 * release 2.0-rc3
 * use hash table in error mapping routines instead of linear search
 * added all errors from fossil, vacfs, and u9fs - now we need to trim down

====== 05/03/2005 - ericvh ====
 * switch to using lib/parser.c for command line parsing
 * change default user to nobody
 * re-enable slabs and remove slab debug
 * enable kernel slab debug options and fix corrupts slab names\
 * rework slab from session based to msize based

====== 05/02/2005 - ericvh ====
 * clean up trans_sock a bit more
 * eliminate normal allocation/free leak detection code from mainline
 * fix double-free in t_flush code

====== 04/30/2005 - ericvh ====
 * remove mmap support - support available in mmap branch (unmaintained)
 * clean up error paths in get_sb

====== 04/29/2005 - ericvh ====
 * protocol field shifting for lucho - make sure you update u9fs too
 * remove transient clunks from lookup (broke linux semantics)
 * whole mess of sparse cleanup changes - multithreaded broken for now

====== 04/28/2005 - ericvh ====
 * fix memory leaks in transport and session_init

====== 04/27/2005 - ericvh ====
 * fix t_version tid (to -1) so we work with Plan 9 servers
 * change to C99 initializers
 * CHANGE KCONFIG option to 9P_FS from 9P (will require BK change outside CVS)

====== 04/25/2005 - ericvh ====
 * release 2.0-rc2

====== 04/23/2005 - ericvh ====
 
 * fix mount segfault problem

====== 04/22/2005 - ericvh ====

 Linux-Kernel Mentor Comments responded to:
 * clean-up Documentation (and remove/move in patch/BK)
       * move README to Documentation/v9fs/v9fs.txt
       * integrate AUTHORS into MAINTAINERS
       * remove COPYING, TODO, INSTALL and CHANGELOG
       * get rid of pointless comments in Makefile
 * clean up debug statements and legacy version hacks
       * put debug defines in do {} while(0) loops
       * make sure all printks have a KERN_
       * get rid of redundant/pointless macros
 * style cleanup 
       * fix function comments to match kernel_doc style
       * remove { } on single line if statements
       * get rid of big inlines
       * get rid of global rpc slab
       * return negative on error, 0 on success uniformly
       * fit entire prototype on line when possible
 * prefix all globals with v9fs_
 * 

====== 04/18/2005 - ericvh ====

 * fix atomic while sleeping warning (thanks Lucho)
 * move inline functions to top of vfs_inode to fix build warning (thanks Lucho)

====== 04/13/2005 - ericvh ====

 * fix 9p2000.u Rerror marshalling to match RFC (thanks Russ)
 * release 2.0-rc1

====== 04/12/2005 - ericvh ====
 
 * fix clunk behavior
 * fix oops during mount problems

====== 03/25/2005 - ericvh =====

 * add extended flag
 * add nodevmap flag
 * add then remove nosuid/nosgid flag (done implicitly)

====== 03/24/2005 - ericvh =====

 * split debug prints into debugs and errors
 * add checks for extended mode with link operations
 * allow override of extended mode with a mount option

====== 03/23/2005 - ericvh =====

 * Code cleanup
 * Make debug level settable at mount time

====== 03/22/2005 - ericvh ======

 * fix various problems with mmap support
 * We now pass fsx!

====== 03/20/2005 - ericvh ======

 * add mmap addr operation support

====== 03/19/2005 - ericvh ======

 * add support for hard links
 * mknod file (PIPES, SOCKETS, DEVICES) support

====== 03/17/2005 - ericvh ======

 * fix open modes so we actually do truncate and append correctly
 * code cleanup, do a better job of conditionalizing extensions

====== 03/16/2005 - ericvh ====

 * add support for readlink and followlink
 * add support for creation of symlinks

====== 03/14/2005 - ericvh ====
 
 * revert setattr to using (no-change) values in stat structure
 * revert rename to using (no-change) values in stat structure
 * fix rename bug (was trying to rename parent directory, not sub-dir)
 * fix bug with chown that wouldn't set uid right
   (wasn't setting string name, only n_uid and u9fs was favoring string name)

====== 03/11/2005 - ericvh ====

 * fix setuid and setgid

 ====== 03/03/2005 - ericvh ====
 * rearrange dir structure to make parsing a bit easier
 * debug numeric id and unix[n] extension
 NOTICE: make sure you use a new u9fs, or thing will break

 ====== 03/02/2005 - ericvh ====

 * Add 9P2000.u error semantics
 * Add 9P2000.u numeric ids to directory structures
 * Provision for variable length extension string (unix[n])

 ====== 03/01/2005 - ericvh ====

 * add version check for definition of vfs_permission versus generic_permission
 * add new 9P2000.u changes to 9p.h

 ====== 02/25/2005 - ericvh =====

 * fix t_wstat in set_attr so chmod & chown works
 * fix t_wstat implementation in rename (but u9fs still broken for rename)

 ====== 02/23/2005 - ericvh =====

 Fixed some permissions bugs associated with mounting actual
 Plan 9 file servers.  Also fixed a bug which crept into 
 attach where we were sending server address as the aname.
 We need to start doing a better job about keeping this file
 up-to-date.
 
 ====== 12/15/2004 - ericvh =====

 Some updates (mostly from lucho) which fix up the re-write.
 Seems to pass bonnie and postmark versus u9fs server with
 same performance as before the rewrite.

 ====== 12/03/2004 - ericvh =====

 WARNING: CVS TIP IS UNSTABLE - use test3 if you want some level of 
          stability

 * line for line rewrite
 * major source reorganization
 * move to using slab allocators for several structures (fcall, pkts, mistat)
 * removal of all cacheing operations including addr_ops (required for mmap)

 Sorry for making a somewhat unstable commit.  Didn't want to hold up others
 from making progress with the code while I fixed up the rewrite.  Code should
 be much more approachable now and closer to LKML guidelines.
 
 ====== 11/21/2004 - lucho (via patch to ericvh) ====

 * add info to 9P debug prints

 * move socket receive processing to a kernel thread

 * send t_flush in response to user-interrupted transactions

 ====== 11/09/2004 - ericvh ========

 * restructure debug prints

   removed a bunch of noisy debug prints and restructured with a 
   more simple set of sections.  Disabled logging as it appears to 
   have some form of corruption, may remove immediately soon.

 * Big Kernel Locks
 
   Intended to remove these, but they seem to still be necessary to
   guarentee serialization.  Ended up adding more - will work hard
   to get rid of these in the next round of changes.

 * Sleep/Wakeup in p9client was causing multithreaded problems.  Sprinkled
   liberally with wakeup calls which seems to unwedge threads (assuming
   BKLs in place).  At the very least it passes Bonnie now

 ----------

v9fs-2.0-rc7 patch

---
commit 33c38809fa7ba8854763409352f349b284ae9a57
tree 7d6ca5270f0ecf9306a944a3d39897a97dc9f67f
parent e0d6d71440a3a35c6fc2dde09f8e8d4d7bd44dda
author <ericvh@ericvhG5.(none)> Thu, 02 Jun 2005 13:04:13 -0500
committer <ericvh@ericvhG5.(none)> Thu, 02 Jun 2005 13:04:13 -0500

 Documentation/filesystems/v9fs.txt |   86 ++
 MAINTAINERS                        |   11 
 fs/9p/9p.c                         |  359 +++++++++
 fs/9p/9p.h                         |  339 ++++++++
 fs/9p/Makefile                     |   17 
 fs/9p/conv.c                       |  729 +++++++++++++++++++
 fs/9p/conv.h                       |   35 
 fs/9p/debug.h                      |   69 +
 fs/9p/error.c                      |   92 ++
 fs/9p/error.h                      |  176 ++++
 fs/9p/fid.c                        |  232 ++++++
 fs/9p/fid.h                        |   55 +
 fs/9p/idpool.c                     |  150 +++
 fs/9p/idpool.h                     |   40 +
 fs/9p/mux.c                        |  437 +++++++++++
 fs/9p/mux.h                        |   37 
 fs/9p/trans_sock.c                 |  272 +++++++
 fs/9p/transport.h                  |   42 +
 fs/9p/v9fs.c                       |  412 ++++++++++
 fs/9p/v9fs.h                       |   84 ++
 fs/9p/v9fs_vfs.h                   |   51 +
 fs/9p/vfs_dentry.c                 |  140 +++
 fs/9p/vfs_dir.c                    |  242 ++++++
 fs/9p/vfs_file.c                   |  419 ++++++++++
 fs/9p/vfs_inode.c                  | 1415 +++++++++++++++++++++++++++++++++++++
 fs/9p/vfs_super.c                  |  257 ++++++
 fs/Kconfig                         |   11 
 fs/Makefile                        |    1 
 28 files changed, 6210 insertions(+)

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