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

  For server running on QEMU host with virtio transport:
  
  	mount -t 9p -o trans=virtio <mount_tag> /mnt/9
  
  where mount_tag is the tag associated by the server to each of the exported
  mount points. Each 9P export is seen by the client as a virtio device with an
  associated "mount_tag" property. Available mount tags can be
  seen by reading /sys/bus/virtio/drivers/9pnet_virtio/virtio<n>/mount_tag files.

  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 QEMU 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 or 9p2000.L semantics)
  
    version=name	Select 9P protocol version. Valid options are:
  			9p2000          - Legacy mode (same as noextend)
  			9p2000.u        - Use 9P2000.u protocol
  			9p2000.L        - Use 9P2000.L protocol

    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/nferno/index.html)

  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)