ericvh / 9p-sac

          v9fs: Plan 9 Resource Sharing for Linux
        =======================================

ABOUT
=====

v9fs is a Unix implementation of the Plan 9 9p remote filesystem protocol.

This software was originally developed by Ron Minnich <rminnich@sandia.gov>
and Maya Gokhale.  Additional development by Greg Watson
<gwatson@lanl.gov> and most recently Eric Van Hensbergen
<ericvh@gmail.com>, Latchesar Ionkov <lucho@ionkov.net> and Russ Cox
<rsc@swtch.com>.

The best detailed explanation of the Linux implementation and applications of
the 9p client is available in the form of a USENIX paper:
   http://www.usenix.org/events/usenix05/tech/freenix/hensbergen.html

Other applications are described in the following papers:
  * XCPU & Clustering
    http://xcpu.org/papers/xcpu-talk.pdf
  * KVMFS: control file system for KVM
    http://xcpu.org/papers/kvmfs.pdf
  * CellFS: A New Programming Model for the Cell BE
    http://xcpu.org/papers/cellfs-talk.pdf
  * PROSE I/O: Using 9p to enable Application Partitions
    http://plan9.escet.urjc.es/iwp9/cready/PROSE_iwp9_2006.pdf

USAGE
=====

For remote file server:

  mount -t 9p 10.10.1.2 /mnt/9

For Plan 9 From User Space applications (http://swtch.com/plan9)

  mount -t 9p `namespace`/acme /mnt/9 -o trans=unix,uname=$USER

OPTIONS
=======

  trans=name  select an alternative transport.  Valid options are
      currently:
      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)
      virtio  - connect to the next virtio channel available
        (from lguest or KVM with trans_virtio module)
      rdma  - connect to a specified RDMA channel

  uname=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.

  cache=mode  specifies a caching policy.  By default, no caches are used.
      loose = no attempts are made at consistency,
                                intended for exclusive, read-only mounts
      fscache = use FS-Cache for a persistent, read-only
        cache backend.

  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
      0x100 = display protocol message debug
      0x200 = display Fid debug
      0x400 = display packet debug
      0x800 = display fscache tracing debug

  rfdno=n  the file descriptor for reading with trans=fd

  wfdno=n  the file descriptor for writing with trans=fd

  maxdata=n  the number of bytes to use for 9p packet payload (msize)

  port=n  port to connect to on the remote server

  noextend  force legacy mode (no 9p2000.u semantics)

  dfltuid  attempt to mount as a particular uid

  dfltgid  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.

  access  there are three access modes.
      user  = if a user tries to access a file on v9fs
              filesystem for the first time, v9fs sends an
              attach command (Tattach) for that user.
        This is the default mode.
      <uid> = allows only user with uid=<uid> to access
        the files on the mounted filesystem
      any   = v9fs does single attach and performs all
        operations as one user

  cachetag  cache tag to use the specified persistent cache.
    cache tags for existing cache sessions can be listed at
    /sys/fs/9p/caches. (applies only to cache=fscache)

RESOURCES
=========

Our current recommendation is to use Inferno (http://www.vitanuova.com/inferno)
as the 9p server.  You can start a 9p server under Inferno by issuing the
following command:
   ; styxlisten -A tcp!*!564 export '#U*'

The -A specifies an unauthenticated export.  The 564 is the port # (you may
have to choose a higher port number if running as a normal user).  The '#U*'
specifies exporting the root of the Linux name space.  You may specify a
subset of the namespace by extending the path: '#U*'/tmp would just export
/tmp.  For more information, see the Inferno manual pages covering styxlisten
and export.

A Linux version of the 9p server is now maintained under the npfs project
on sourceforge (http://sourceforge.net/projects/npfs).  The currently
maintained version is the single-threaded version of the server (named spfs)
available from the same SVN repository.

There are user and developer mailing lists available through the v9fs project
on sourceforge (http://sourceforge.net/projects/v9fs).

A stand-alone version of the module (which should build for any 2.6 kernel)
is available via (http://github.com/ericvh/9p-sac/tree/master)

News and other information is maintained on SWiK (http://swik.net/v9fs)
and the Wiki (http://sf.net/apps/mediawiki/v9fs/index.php).

Bug reports may be issued through the kernel.org bugzilla 
(http://bugzilla.kernel.org)

For more information on the Plan 9 Operating System check out
http://plan9.bell-labs.com/plan9

For information on Plan 9 from User Space (Plan 9 applications and libraries
ported to Linux/BSD/OSX/etc) check out http://swtch.com/plan9


STATUS
======

The 2.6 kernel support is working on PPC and x86.

PLEASE USE THE KERNEL BUGZILLA TO REPORT PROBLEMS. (http://bugzilla.kernel.org)