forked from Minki/linux
b529c06f9d
The page originally referenced to checkout Plan9 application and libraries have been missing for quite some time and the development is carried out in github and documented on this new site. Signed-off-by: Juan Manuel Méndez Rey <vejeta@gmail.com> Link: https://lore.kernel.org/r/20200426015250.GA35090@camelot Signed-off-by: Jonathan Corbet <corbet@lwn.net>
196 lines
6.6 KiB
ReStructuredText
196 lines
6.6 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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=======================================
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v9fs: Plan 9 Resource Sharing for Linux
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=======================================
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About
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=====
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v9fs is a Unix implementation of the Plan 9 9p remote filesystem protocol.
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This software was originally developed by Ron Minnich <rminnich@sandia.gov>
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and Maya Gokhale. Additional development by Greg Watson
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<gwatson@lanl.gov> and most recently Eric Van Hensbergen
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<ericvh@gmail.com>, Latchesar Ionkov <lucho@ionkov.net> and Russ Cox
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<rsc@swtch.com>.
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The best detailed explanation of the Linux implementation and applications of
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the 9p client is available in the form of a USENIX paper:
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http://www.usenix.org/events/usenix05/tech/freenix/hensbergen.html
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Other applications are described in the following papers:
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* XCPU & Clustering
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http://xcpu.org/papers/xcpu-talk.pdf
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* KVMFS: control file system for KVM
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http://xcpu.org/papers/kvmfs.pdf
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* CellFS: A New Programming Model for the Cell BE
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http://xcpu.org/papers/cellfs-talk.pdf
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* PROSE I/O: Using 9p to enable Application Partitions
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http://plan9.escet.urjc.es/iwp9/cready/PROSE_iwp9_2006.pdf
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* VirtFS: A Virtualization Aware File System pass-through
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http://goo.gl/3WPDg
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Usage
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=====
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For remote file server::
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mount -t 9p 10.10.1.2 /mnt/9
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For Plan 9 From User Space applications (http://swtch.com/plan9)::
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mount -t 9p `namespace`/acme /mnt/9 -o trans=unix,uname=$USER
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For server running on QEMU host with virtio transport::
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mount -t 9p -o trans=virtio <mount_tag> /mnt/9
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where mount_tag is the tag associated by the server to each of the exported
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mount points. Each 9P export is seen by the client as a virtio device with an
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associated "mount_tag" property. Available mount tags can be
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seen by reading /sys/bus/virtio/drivers/9pnet_virtio/virtio<n>/mount_tag files.
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Options
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=======
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============= ===============================================================
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trans=name select an alternative transport. Valid options are
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currently:
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======== ============================================
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unix specifying a named pipe mount point
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tcp specifying a normal TCP/IP connection
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fd used passed file descriptors for connection
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(see rfdno and wfdno)
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virtio connect to the next virtio channel available
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(from QEMU with trans_virtio module)
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rdma connect to a specified RDMA channel
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======== ============================================
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uname=name user name to attempt mount as on the remote server. The
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server may override or ignore this value. Certain user
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names may require authentication.
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aname=name aname specifies the file tree to access when the server is
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offering several exported file systems.
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cache=mode specifies a caching policy. By default, no caches are used.
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none
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default no cache policy, metadata and data
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alike are synchronous.
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loose
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no attempts are made at consistency,
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intended for exclusive, read-only mounts
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fscache
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use FS-Cache for a persistent, read-only
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cache backend.
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mmap
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minimal cache that is only used for read-write
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mmap. Northing else is cached, like cache=none
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debug=n specifies debug level. The debug level is a bitmask.
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===== ================================
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0x01 display verbose error messages
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0x02 developer debug (DEBUG_CURRENT)
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0x04 display 9p trace
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0x08 display VFS trace
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0x10 display Marshalling debug
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0x20 display RPC debug
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0x40 display transport debug
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0x80 display allocation debug
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0x100 display protocol message debug
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0x200 display Fid debug
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0x400 display packet debug
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0x800 display fscache tracing debug
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===== ================================
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rfdno=n the file descriptor for reading with trans=fd
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wfdno=n the file descriptor for writing with trans=fd
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msize=n the number of bytes to use for 9p packet payload
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port=n port to connect to on the remote server
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noextend force legacy mode (no 9p2000.u or 9p2000.L semantics)
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version=name Select 9P protocol version. Valid options are:
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======== ==============================
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9p2000 Legacy mode (same as noextend)
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9p2000.u Use 9P2000.u protocol
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9p2000.L Use 9P2000.L protocol
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======== ==============================
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dfltuid attempt to mount as a particular uid
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dfltgid attempt to mount with a particular gid
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afid security channel - used by Plan 9 authentication protocols
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nodevmap do not map special files - represent them as normal files.
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This can be used to share devices/named pipes/sockets between
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hosts. This functionality will be expanded in later versions.
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access there are four access modes.
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user
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if a user tries to access a file on v9fs
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filesystem for the first time, v9fs sends an
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attach command (Tattach) for that user.
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This is the default mode.
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<uid>
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allows only user with uid=<uid> to access
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the files on the mounted filesystem
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any
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v9fs does single attach and performs all
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operations as one user
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clien
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ACL based access check on the 9p client
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side for access validation
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cachetag cache tag to use the specified persistent cache.
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cache tags for existing cache sessions can be listed at
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/sys/fs/9p/caches. (applies only to cache=fscache)
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============= ===============================================================
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Behavior
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========
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This section aims at describing 9p 'quirks' that can be different
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from a local filesystem behaviors.
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- Setting O_NONBLOCK on a file will make client reads return as early
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as the server returns some data instead of trying to fill the read
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buffer with the requested amount of bytes or end of file is reached.
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Resources
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=========
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Protocol specifications are maintained on github:
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http://ericvh.github.com/9p-rfc/
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9p client and server implementations are listed on
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http://9p.cat-v.org/implementations
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A 9p2000.L server is being developed by LLNL and can be found
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at http://code.google.com/p/diod/
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There are user and developer mailing lists available through the v9fs project
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on sourceforge (http://sourceforge.net/projects/v9fs).
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News and other information is maintained on a Wiki.
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(http://sf.net/apps/mediawiki/v9fs/index.php).
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Bug reports are best issued via the mailing list.
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For more information on the Plan 9 Operating System check out
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http://plan9.bell-labs.com/plan9
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For information on Plan 9 from User Space (Plan 9 applications and libraries
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ported to Linux/BSD/OSX/etc) check out https://9fans.github.io/plan9port/
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