Documentation/filesystems/9p.txt

   1                     v9fs: Plan 9 Resource Sharing for Linux
   2                     =======================================
   3
   4 ABOUT
   5 =====
   6
   7 v9fs is a Unix implementation of the Plan 9 9p remote filesystem protocol.
   8
   9 This software was originally developed by Ron Minnich <rminnich@sandia.gov>
  10 and Maya Gokhale.  Additional development by Greg Watson
  11 <gwatson@lanl.gov> and most recently Eric Van Hensbergen
  12 <ericvh@gmail.com>, Latchesar Ionkov <lucho@ionkov.net> and Russ Cox
  13 <rsc@swtch.com>.
  14
  15 The best detailed explanation of the Linux implementation and applications of
  16 the 9p client is available in the form of a USENIX paper:
  17    http://www.usenix.org/events/usenix05/tech/freenix/hensbergen.html
  18
  19 Other applications are described in the following papers:
  20         * XCPU & Clustering
  21                 http://xcpu.org/papers/xcpu-talk.pdf
  22         * KVMFS: control file system for KVM
  23                 http://xcpu.org/papers/kvmfs.pdf
  24         * CellFS: A New Programming Model for the Cell BE
  25                 http://xcpu.org/papers/cellfs-talk.pdf
  26         * PROSE I/O: Using 9p to enable Application Partitions
  27                 http://plan9.escet.urjc.es/iwp9/cready/PROSE_iwp9_2006.pdf
  28
  29 USAGE
  30 =====
  31
  32 For remote file server:
  33
  34         mount -t 9p 10.10.1.2 /mnt/9
  35
  36 For Plan 9 From User Space applications (http://swtch.com/plan9)
  37
  38         mount -t 9p `namespace`/acme /mnt/9 -o trans=unix,uname=$USER
  39
  40 For server running on QEMU host with virtio transport:
  41
  42         mount -t 9p -o trans=virtio <mount_tag> /mnt/9
  43
  44 where mount_tag is the tag associated by the server to each of the exported
  45 mount points. Each 9P export is seen by the client as a virtio device with an
  46 associated "mount_tag" property. Available mount tags can be
  47 seen by reading /sys/bus/virtio/drivers/9pnet_virtio/virtio<n>/mount_tag files.
  48
  49 OPTIONS
  50 =======
  51
  52   trans=name    select an alternative transport.  Valid options are
  53                 currently:
  54                         unix    - specifying a named pipe mount point
  55                         tcp     - specifying a normal TCP/IP connection
  56                         fd      - used passed file descriptors for connection
  57                                 (see rfdno and wfdno)
  58                         virtio  - connect to the next virtio channel available
  59                                 (from QEMU with trans_virtio module)
  60                         rdma    - connect to a specified RDMA channel
  61
  62   uname=name    user name to attempt mount as on the remote server.  The
  63                 server may override or ignore this value.  Certain user
  64                 names may require authentication.
  65
  66   aname=name    aname specifies the file tree to access when the server is
  67                 offering several exported file systems.
  68
  69   cache=mode    specifies a caching policy.  By default, no caches are used.
  70                         loose = no attempts are made at consistency,
  71                                 intended for exclusive, read-only mounts
  72                         fscache = use FS-Cache for a persistent, read-only
  73                                 cache backend.
  74
  75   debug=n       specifies debug level.  The debug level is a bitmask.
  76                         0x01  = display verbose error messages
  77                         0x02  = developer debug (DEBUG_CURRENT)
  78                         0x04  = display 9p trace
  79                         0x08  = display VFS trace
  80                         0x10  = display Marshalling debug
  81                         0x20  = display RPC debug
  82                         0x40  = display transport debug
  83                         0x80  = display allocation debug
  84                         0x100 = display protocol message debug
  85                         0x200 = display Fid debug
  86                         0x400 = display packet debug
  87                         0x800 = display fscache tracing debug
  88
  89   rfdno=n       the file descriptor for reading with trans=fd
  90
  91   wfdno=n       the file descriptor for writing with trans=fd
  92
  93   maxdata=n     the number of bytes to use for 9p packet payload (msize)
  94
  95   port=n        port to connect to on the remote server
  96
  97   noextend      force legacy mode (no 9p2000.u or 9p2000.L semantics)
  98
  99   version=name  Select 9P protocol version. Valid options are:
 100                         9p2000          - Legacy mode (same as noextend)
 101                         9p2000.u        - Use 9P2000.u protocol
 102                         9p2000.L        - Use 9P2000.L protocol
 103
 104   dfltuid       attempt to mount as a particular uid
 105
 106   dfltgid       attempt to mount with a particular gid
 107
 108   afid          security channel - used by Plan 9 authentication protocols
 109
 110   nodevmap      do not map special files - represent them as normal files.
 111                 This can be used to share devices/named pipes/sockets between
 112                 hosts.  This functionality will be expanded in later versions.
 113
 114   access        there are three access modes.
 115                         user  = if a user tries to access a file on v9fs
 116                                 filesystem for the first time, v9fs sends an
 117                                 attach command (Tattach) for that user.
 118                                 This is the default mode.
 119                         <uid> = allows only user with uid=<uid> to access
 120                                 the files on the mounted filesystem
 121                         any   = v9fs does single attach and performs all
 122                                 operations as one user
 123
 124   cachetag      cache tag to use the specified persistent cache.
 125                 cache tags for existing cache sessions can be listed at
 126                 /sys/fs/9p/caches. (applies only to cache=fscache)
 127
 128 RESOURCES
 129 =========
 130
 131 Our current recommendation is to use Inferno (http://www.vitanuova.com/nferno/index.html)
 132 as the 9p server.  You can start a 9p server under Inferno by issuing the
 133 following command:
 134    ; styxlisten -A tcp!*!564 export '#U*'
 135
 136 The -A specifies an unauthenticated export.  The 564 is the port # (you may
 137 have to choose a higher port number if running as a normal user).  The '#U*'
 138 specifies exporting the root of the Linux name space.  You may specify a
 139 subset of the namespace by extending the path: '#U*'/tmp would just export
 140 /tmp.  For more information, see the Inferno manual pages covering styxlisten
 141 and export.
 142
 143 A Linux version of the 9p server is now maintained under the npfs project
 144 on sourceforge (http://sourceforge.net/projects/npfs).  The currently
 145 maintained version is the single-threaded version of the server (named spfs)
 146 available from the same SVN repository.
 147
 148 There are user and developer mailing lists available through the v9fs project
 149 on sourceforge (http://sourceforge.net/projects/v9fs).
 150
 151 A stand-alone version of the module (which should build for any 2.6 kernel)
 152 is available via (http://github.com/ericvh/9p-sac/tree/master)
 153
 154 News and other information is maintained on SWiK (http://swik.net/v9fs)
 155 and the Wiki (http://sf.net/apps/mediawiki/v9fs/index.php).
 156
 157 Bug reports may be issued through the kernel.org bugzilla
 158 (http://bugzilla.kernel.org)
 159
 160 For more information on the Plan 9 Operating System check out
 161 http://plan9.bell-labs.com/plan9
 162
 163 For information on Plan 9 from User Space (Plan 9 applications and libraries
 164 ported to Linux/BSD/OSX/etc) check out http://swtch.com/plan9
 165
 166
 167 STATUS
 168 ======
 169
 170 The 2.6 kernel support is working on PPC and x86.
 171
 172 PLEASE USE THE KERNEL BUGZILLA TO REPORT PROBLEMS. (http://bugzilla.kernel.org)
 173