docs: filesystems: convert 9p.txt to ReST

- Add a SPDX header;
- Add a document title;
- Adjust section titles;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add table markups;
- Add it to filesystems/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/96a060b7b5c0c3838ab1751addfe4d6d3bc37bd6.1581955849.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

2 files changed, 70 insertions, 45 deletions

diff --git a/Documentation/filesystems/9p.txt b/Documentation/filesystems/9p.rst
index fec7144e817c..f054d1c45e86 100644
--- a/Documentation/filesystems/9p.txt
+++ b/Documentation/filesystems/9p.rst
@@ -1,7 +1,10 @@
-	  	    v9fs: Plan 9 Resource Sharing for Linux
-		    =======================================
+.. SPDX-License-Identifier: GPL-2.0
 
-ABOUT
+=======================================
+v9fs: Plan 9 Resource Sharing for Linux
+=======================================
+
+About
 =====
 
 v9fs is a Unix implementation of the Plan 9 9p remote filesystem protocol.
@@ -14,32 +17,34 @@ and Maya Gokhale.  Additional development by Greg Watson
 
 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
+	  http://xcpu.org/papers/xcpu-talk.pdf
 	* KVMFS: control file system for KVM
-		http://xcpu.org/papers/kvmfs.pdf
+	  http://xcpu.org/papers/kvmfs.pdf
 	* CellFS: A New Programming Model for the Cell BE
-		http://xcpu.org/papers/cellfs-talk.pdf
+	  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
+	  http://plan9.escet.urjc.es/iwp9/cready/PROSE_iwp9_2006.pdf
 	* VirtFS: A Virtualization Aware File System pass-through
-		http://goo.gl/3WPDg
+	  http://goo.gl/3WPDg
 
-USAGE
+Usage
 =====
 
-For remote file server:
+For remote file server::
 
 	mount -t 9p 10.10.1.2 /mnt/9
 
-For Plan 9 From User Space applications (http://swtch.com/plan9)
+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:
+For server running on QEMU host with virtio transport::
 
 	mount -t 9p -o trans=virtio <mount_tag> /mnt/9
 
@@ -48,18 +53,22 @@ 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
+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
+
+			========  ============================================
+			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
@@ -69,28 +78,36 @@ OPTIONS
   		offering several exported file systems.
 
   cache=mode	specifies a caching policy.  By default, no caches are used.
-                        none = default no cache policy, metadata and data
+
+                        none
+				default no cache policy, metadata and data
                                 alike are synchronous.
-			loose = no attempts are made at consistency,
+			loose
+				no attempts are made at consistency,
                                 intended for exclusive, read-only mounts
-                        fscache = use FS-Cache for a persistent, read-only
+                        fscache
+				use FS-Cache for a persistent, read-only
 				cache backend.
-                        mmap = minimal cache that is only used for read-write
+                        mmap
+				minimal cache that is only used for read-write
                                 mmap.  Northing else is cached, like cache=none
 
   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
+
+			=====   ================================
+			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
 
@@ -103,9 +120,12 @@ OPTIONS
   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
+
+			========        ==============================
+			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
 
@@ -118,22 +138,27 @@ OPTIONS
 		hosts.  This functionality will be expanded in later versions.
 
   access	there are four access modes.
-			user  = if a user tries to access a file on v9fs
+			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
+			<uid>
+				allows only user with uid=<uid> to access
 				the files on the mounted filesystem
-			any   = v9fs does single attach and performs all
+			any
+				v9fs does single attach and performs all
 				operations as one user
-			client = ACL based access check on the 9p client
+			clien
+				 ACL based access check on the 9p client
 			         side for access validation
 
   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
+Resources
 =========
 
 Protocol specifications are maintained on github:
@@ -158,4 +183,3 @@ 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
-
diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst
index 45d791905e91..a9330c3f8c2e 100644
--- a/Documentation/filesystems/index.rst
+++ b/Documentation/filesystems/index.rst
@@ -46,6 +46,7 @@ Documentation for filesystem implementations.
 .. toctree::
    :maxdepth: 2
 
+   9p
    autofs
    fuse
    overlayfs