1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 ======================================= 3 =======================================
4 v9fs: Plan 9 Resource Sharing for Linux 4 v9fs: Plan 9 Resource Sharing for Linux
5 ======================================= 5 =======================================
6 6
7 About 7 About
8 ===== 8 =====
9 9
10 v9fs is a Unix implementation of the Plan 9 9p 10 v9fs is a Unix implementation of the Plan 9 9p remote filesystem protocol.
11 11
12 This software was originally developed by Ron < 12 This software was originally developed by Ron Minnich <rminnich@sandia.gov>
13 and Maya Gokhale. Additional development by G 13 and Maya Gokhale. Additional development by Greg Watson
14 <gwatson@lanl.gov> and most recently Eric Van H 14 <gwatson@lanl.gov> and most recently Eric Van Hensbergen
15 <ericvh@gmail.com>, Latchesar Ionkov <lucho@ion 15 <ericvh@gmail.com>, Latchesar Ionkov <lucho@ionkov.net> and Russ Cox
16 <rsc@swtch.com>. 16 <rsc@swtch.com>.
17 17
18 The best detailed explanation of the Linux imp 18 The best detailed explanation of the Linux implementation and applications of
19 the 9p client is available in the form of a US 19 the 9p client is available in the form of a USENIX paper:
20 20
21 https://www.usenix.org/events/usenix05/tech 21 https://www.usenix.org/events/usenix05/tech/freenix/hensbergen.html
22 22
23 Other applications are described in the follow 23 Other applications are described in the following papers:
24 24
25 * XCPU & Clustering 25 * XCPU & Clustering
26 http://xcpu.org/papers/xcpu-talk.pdf 26 http://xcpu.org/papers/xcpu-talk.pdf
27 * KVMFS: control file system for KVM 27 * KVMFS: control file system for KVM
28 http://xcpu.org/papers/kvmfs.pdf 28 http://xcpu.org/papers/kvmfs.pdf
29 * CellFS: A New Programming Model for 29 * CellFS: A New Programming Model for the Cell BE
30 http://xcpu.org/papers/cellfs-talk.p 30 http://xcpu.org/papers/cellfs-talk.pdf
31 * PROSE I/O: Using 9p to enable Applic 31 * PROSE I/O: Using 9p to enable Application Partitions
32 http://plan9.escet.urjc.es/iwp9/crea 32 http://plan9.escet.urjc.es/iwp9/cready/PROSE_iwp9_2006.pdf
33 * VirtFS: A Virtualization Aware File 33 * VirtFS: A Virtualization Aware File System pass-through
34 http://goo.gl/3WPDg 34 http://goo.gl/3WPDg
35 35
36 Usage 36 Usage
37 ===== 37 =====
38 38
39 For remote file server:: 39 For remote file server::
40 40
41 mount -t 9p 10.10.1.2 /mnt/9 41 mount -t 9p 10.10.1.2 /mnt/9
42 42
43 For Plan 9 From User Space applications (http: 43 For Plan 9 From User Space applications (http://swtch.com/plan9)::
44 44
45 mount -t 9p `namespace`/acme /mnt/9 -o 45 mount -t 9p `namespace`/acme /mnt/9 -o trans=unix,uname=$USER
46 46
47 For server running on QEMU host with virtio tr 47 For server running on QEMU host with virtio transport::
48 48
49 mount -t 9p -o trans=virtio <mount_tag 49 mount -t 9p -o trans=virtio <mount_tag> /mnt/9
50 50
51 where mount_tag is the tag associated by the s 51 where mount_tag is the tag associated by the server to each of the exported
52 mount points. Each 9P export is seen by the cl 52 mount points. Each 9P export is seen by the client as a virtio device with an
53 associated "mount_tag" property. Available mou 53 associated "mount_tag" property. Available mount tags can be
54 seen by reading /sys/bus/virtio/drivers/9pnet_ 54 seen by reading /sys/bus/virtio/drivers/9pnet_virtio/virtio<n>/mount_tag files.
55 55
56 Options 56 Options
57 ======= 57 =======
58 58
59 ============= ============================== 59 ============= ===============================================================
60 trans=name select an alternative transpor 60 trans=name select an alternative transport. Valid options are
61 currently: 61 currently:
62 62
63 ======== ============ 63 ======== ============================================
64 unix specifying a 64 unix specifying a named pipe mount point
65 tcp specifying a 65 tcp specifying a normal TCP/IP connection
66 fd used passed 66 fd used passed file descriptors for connection
67 (see rfdno a 67 (see rfdno and wfdno)
68 virtio connect to t 68 virtio connect to the next virtio channel available
69 (from QEMU w 69 (from QEMU with trans_virtio module)
70 rdma connect to a 70 rdma connect to a specified RDMA channel
71 ======== ============ 71 ======== ============================================
72 72
73 uname=name user name to attempt mount as 73 uname=name user name to attempt mount as on the remote server. The
74 server may override or ignore 74 server may override or ignore this value. Certain user
75 names may require authenticati 75 names may require authentication.
76 76
77 aname=name aname specifies the file tree 77 aname=name aname specifies the file tree to access when the server is
78 offering several exported file 78 offering several exported file systems.
79 79
80 cache=mode specifies a caching policy. B 80 cache=mode specifies a caching policy. By default, no caches are used.
81 The mode can be specified as a 81 The mode can be specified as a bitmask or by using one of the
82 preexisting common 'shortcuts' 82 preexisting common 'shortcuts'.
83 The bitmask is described below 83 The bitmask is described below: (unspecified bits are reserved)
84 84
85 ========== ========== 85 ========== ====================================================
86 0b00000000 all caches 86 0b00000000 all caches disabled, mmap disabled
87 0b00000001 file cache 87 0b00000001 file caches enabled
88 0b00000010 meta-data 88 0b00000010 meta-data caches enabled
89 0b00000100 writeback 89 0b00000100 writeback behavior (as opposed to writethrough)
90 0b00001000 loose cach 90 0b00001000 loose caches (no explicit consistency with server)
91 0b10000000 fscache en 91 0b10000000 fscache enabled for persistent caching
92 ========== ========== 92 ========== ====================================================
93 93
94 The current shortcuts and thei 94 The current shortcuts and their associated bitmask are:
95 95
96 ========= ========== 96 ========= ====================================================
97 none 0b00000000 97 none 0b00000000 (no caching)
98 readahead 0b00000001 98 readahead 0b00000001 (only read-ahead file caching)
99 mmap 0b00000101 99 mmap 0b00000101 (read-ahead + writeback file cache)
100 loose 0b00001111 100 loose 0b00001111 (non-coherent file and meta-data caches)
101 fscache 0b10001111 101 fscache 0b10001111 (persistent loose cache)
102 ========= ========== 102 ========= ====================================================
103 103
104 NOTE: only these shortcuts are 104 NOTE: only these shortcuts are tested modes of operation at the
105 moment, so using other combina 105 moment, so using other combinations of bit-patterns is not
106 known to work. Work on better 106 known to work. Work on better cache support is in progress.
107 107
108 IMPORTANT: loose caches (and b 108 IMPORTANT: loose caches (and by extension at the moment fscache)
109 do not necessarily validate ca 109 do not necessarily validate cached values on the server. In other
110 words changes on the server ar 110 words changes on the server are not guaranteed to be reflected
111 on the client system. Only us 111 on the client system. Only use this mode of operation if you
112 have an exclusive mount and th 112 have an exclusive mount and the server will modify the filesystem
113 underneath you. 113 underneath you.
114 114
115 debug=n specifies debug level. The de 115 debug=n specifies debug level. The debug level is a bitmask.
116 116
117 ===== ============== 117 ===== ================================
118 0x01 display verbos 118 0x01 display verbose error messages
119 0x02 developer debu 119 0x02 developer debug (DEBUG_CURRENT)
120 0x04 display 9p tra 120 0x04 display 9p trace
121 0x08 display VFS tr 121 0x08 display VFS trace
122 0x10 display Marsha 122 0x10 display Marshalling debug
123 0x20 display RPC de 123 0x20 display RPC debug
124 0x40 display transp 124 0x40 display transport debug
125 0x80 display alloca 125 0x80 display allocation debug
126 0x100 display protoc 126 0x100 display protocol message debug
127 0x200 display Fid de 127 0x200 display Fid debug
128 0x400 display packet 128 0x400 display packet debug
129 0x800 display fscach 129 0x800 display fscache tracing debug
130 ===== ============== 130 ===== ================================
131 131
132 rfdno=n the file descriptor for readin 132 rfdno=n the file descriptor for reading with trans=fd
133 133
134 wfdno=n the file descriptor for writin 134 wfdno=n the file descriptor for writing with trans=fd
135 135
136 msize=n the number of bytes to use for 136 msize=n the number of bytes to use for 9p packet payload
137 137
138 port=n port to connect to on the remo 138 port=n port to connect to on the remote server
139 139
140 noextend force legacy mode (no 9p2000.u 140 noextend force legacy mode (no 9p2000.u or 9p2000.L semantics)
141 141
142 version=name Select 9P protocol version. Va 142 version=name Select 9P protocol version. Valid options are:
143 143
144 ======== ====== 144 ======== ==============================
145 9p2000 Legacy 145 9p2000 Legacy mode (same as noextend)
146 9p2000.u Use 9P 146 9p2000.u Use 9P2000.u protocol
147 9p2000.L Use 9P 147 9p2000.L Use 9P2000.L protocol
148 ======== ====== 148 ======== ==============================
149 149
150 dfltuid attempt to mount as a particul 150 dfltuid attempt to mount as a particular uid
151 151
152 dfltgid attempt to mount with a partic 152 dfltgid attempt to mount with a particular gid
153 153
154 afid security channel - used by Pla 154 afid security channel - used by Plan 9 authentication protocols
155 155
156 nodevmap do not map special files - rep 156 nodevmap do not map special files - represent them as normal files.
157 This can be used to share devi 157 This can be used to share devices/named pipes/sockets between
158 hosts. This functionality wil 158 hosts. This functionality will be expanded in later versions.
159 159
160 directio bypass page cache on all read/ 160 directio bypass page cache on all read/write operations
161 161
162 ignoreqv ignore qid.version==0 as a mar 162 ignoreqv ignore qid.version==0 as a marker to ignore cache
163 163
164 noxattr do not offer xattr functions o 164 noxattr do not offer xattr functions on this mount.
165 165
166 access there are four access modes. 166 access there are four access modes.
167 user 167 user
168 if a user trie 168 if a user tries to access a file on v9fs
169 filesystem for 169 filesystem for the first time, v9fs sends an
170 attach command 170 attach command (Tattach) for that user.
171 This is the de 171 This is the default mode.
172 <uid> 172 <uid>
173 allows only us 173 allows only user with uid=<uid> to access
174 the files on t 174 the files on the mounted filesystem
175 any 175 any
176 v9fs does sing 176 v9fs does single attach and performs all
177 operations as 177 operations as one user
178 clien 178 clien
179 ACL based acc 179 ACL based access check on the 9p client
180 side for acce 180 side for access validation
181 181
182 cachetag cache tag to use the specified 182 cachetag cache tag to use the specified persistent cache.
183 cache tags for existing cache 183 cache tags for existing cache sessions can be listed at
184 /sys/fs/9p/caches. (applies on 184 /sys/fs/9p/caches. (applies only to cache=fscache)
185 ============= ============================== 185 ============= ===============================================================
186 186
187 Behavior 187 Behavior
188 ======== 188 ========
189 189
190 This section aims at describing 9p 'quirks' th 190 This section aims at describing 9p 'quirks' that can be different
191 from a local filesystem behaviors. 191 from a local filesystem behaviors.
192 192
193 - Setting O_NONBLOCK on a file will make clie 193 - Setting O_NONBLOCK on a file will make client reads return as early
194 as the server returns some data instead of 194 as the server returns some data instead of trying to fill the read
195 buffer with the requested amount of bytes o 195 buffer with the requested amount of bytes or end of file is reached.
196 196
197 Resources 197 Resources
198 ========= 198 =========
199 199
200 Protocol specifications are maintained on gith 200 Protocol specifications are maintained on github:
201 http://ericvh.github.com/9p-rfc/ 201 http://ericvh.github.com/9p-rfc/
202 202
203 9p client and server implementations are liste 203 9p client and server implementations are listed on
204 http://9p.cat-v.org/implementations 204 http://9p.cat-v.org/implementations
205 205
206 A 9p2000.L server is being developed by LLNL a 206 A 9p2000.L server is being developed by LLNL and can be found
207 at http://code.google.com/p/diod/ 207 at http://code.google.com/p/diod/
208 208
209 There are user and developer mailing lists ava 209 There are user and developer mailing lists available through the v9fs project
210 on sourceforge (http://sourceforge.net/project 210 on sourceforge (http://sourceforge.net/projects/v9fs).
211 211
212 News and other information is maintained on a 212 News and other information is maintained on a Wiki.
213 (http://sf.net/apps/mediawiki/v9fs/index.php). 213 (http://sf.net/apps/mediawiki/v9fs/index.php).
214 214
215 Bug reports are best issued via the mailing li 215 Bug reports are best issued via the mailing list.
216 216
217 For more information on the Plan 9 Operating S 217 For more information on the Plan 9 Operating System check out
218 http://plan9.bell-labs.com/plan9 218 http://plan9.bell-labs.com/plan9
219 219
220 For information on Plan 9 from User Space (Pla 220 For information on Plan 9 from User Space (Plan 9 applications and libraries
221 ported to Linux/BSD/OSX/etc) check out https:/ 221 ported to Linux/BSD/OSX/etc) check out https://9fans.github.io/plan9port/
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