docs: filesystems: convert afs.txt to ReST

- Add a SPDX header;
- Adjust document and section titles;
- Comment out text-only ToC;
- Mark literal blocks as such;
- Add it to filesystems/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/d77f5afdb5da0f8b0ec3dbe720aef23f1ce73bb5.1581955849.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Mauro Carvalho Chehab 2020-02-17 17:11:50 +01:00 committed by Jonathan Corbet
parent 7627216830
commit ca6e9049a0
2 changed files with 34 additions and 40 deletions

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@ -1,8 +1,10 @@
====================
kAFS: AFS FILESYSTEM
====================
.. SPDX-License-Identifier: GPL-2.0
Contents:
====================
kAFS: AFS FILESYSTEM
====================
.. Contents:
- Overview.
- Usage.
@ -14,8 +16,7 @@ Contents:
- The @sys substitution.
========
OVERVIEW
Overview
========
This filesystem provides a fairly simple secure AFS filesystem driver. It is
@ -35,35 +36,33 @@ It does not yet support the following AFS features:
(*) pioctl() system call.
===========
COMPILATION
Compilation
===========
The filesystem should be enabled by turning on the kernel configuration
options:
options::
CONFIG_AF_RXRPC - The RxRPC protocol transport
CONFIG_RXKAD - The RxRPC Kerberos security handler
CONFIG_AFS - The AFS filesystem
Additionally, the following can be turned on to aid debugging:
Additionally, the following can be turned on to aid debugging::
CONFIG_AF_RXRPC_DEBUG - Permit AF_RXRPC debugging to be enabled
CONFIG_AFS_DEBUG - Permit AFS debugging to be enabled
They permit the debugging messages to be turned on dynamically by manipulating
the masks in the following files:
the masks in the following files::
/sys/module/af_rxrpc/parameters/debug
/sys/module/kafs/parameters/debug
=====
USAGE
Usage
=====
When inserting the driver modules the root cell must be specified along with a
list of volume location server IP addresses:
list of volume location server IP addresses::
modprobe rxrpc
modprobe kafs rootcell=cambridge.redhat.com:172.16.18.73:172.16.18.91
@ -77,14 +76,14 @@ The second module is the kerberos RxRPC security driver, and the third module
is the actual filesystem driver for the AFS filesystem.
Once the module has been loaded, more modules can be added by the following
procedure:
procedure::
echo add grand.central.org 18.9.48.14:128.2.203.61:130.237.48.87 >/proc/fs/afs/cells
Where the parameters to the "add" command are the name of a cell and a list of
volume location servers within that cell, with the latter separated by colons.
Filesystems can be mounted anywhere by commands similar to the following:
Filesystems can be mounted anywhere by commands similar to the following::
mount -t afs "%cambridge.redhat.com:root.afs." /afs
mount -t afs "#cambridge.redhat.com:root.cell." /afs/cambridge
@ -104,8 +103,7 @@ named volume will be looked up in the cell specified during modprobe.
Additional cells can be added through /proc (see later section).
===========
MOUNTPOINTS
Mountpoints
===========
AFS has a concept of mountpoints. In AFS terms, these are specially formatted
@ -123,42 +121,40 @@ culled first. If all are culled, then the requested volume will also be
unmounted, otherwise error EBUSY will be returned.
This can be used by the administrator to attempt to unmount the whole AFS tree
mounted on /afs in one go by doing:
mounted on /afs in one go by doing::
umount /afs
============
DYNAMIC ROOT
Dynamic Root
============
A mount option is available to create a serverless mount that is only usable
for dynamic lookup. Creating such a mount can be done by, for example:
for dynamic lookup. Creating such a mount can be done by, for example::
mount -t afs none /afs -o dyn
This creates a mount that just has an empty directory at the root. Attempting
to look up a name in this directory will cause a mountpoint to be created that
looks up a cell of the same name, for example:
looks up a cell of the same name, for example::
ls /afs/grand.central.org/
===============
PROC FILESYSTEM
Proc Filesystem
===============
The AFS modules creates a "/proc/fs/afs/" directory and populates it:
(*) A "cells" file that lists cells currently known to the afs module and
their usage counts:
their usage counts::
[root@andromeda ~]# cat /proc/fs/afs/cells
USE NAME
3 cambridge.redhat.com
(*) A directory per cell that contains files that list volume location
servers, volumes, and active servers known within that cell.
servers, volumes, and active servers known within that cell::
[root@andromeda ~]# cat /proc/fs/afs/cambridge.redhat.com/servers
USE ADDR STATE
@ -171,8 +167,7 @@ The AFS modules creates a "/proc/fs/afs/" directory and populates it:
1 Val 20000000 20000001 20000002 root.afs
=================
THE CELL DATABASE
The Cell Database
=================
The filesystem maintains an internal database of all the cells it knows and the
@ -181,7 +176,7 @@ the system belongs is added to the database when modprobe is performed by the
"rootcell=" argument or, if compiled in, using a "kafs.rootcell=" argument on
the kernel command line.
Further cells can be added by commands similar to the following:
Further cells can be added by commands similar to the following::
echo add CELLNAME VLADDR[:VLADDR][:VLADDR]... >/proc/fs/afs/cells
echo add grand.central.org 18.9.48.14:128.2.203.61:130.237.48.87 >/proc/fs/afs/cells
@ -189,8 +184,7 @@ Further cells can be added by commands similar to the following:
No other cell database operations are available at this time.
========
SECURITY
Security
========
Secure operations are initiated by acquiring a key using the klog program. A
@ -198,17 +192,17 @@ very primitive klog program is available at:
http://people.redhat.com/~dhowells/rxrpc/klog.c
This should be compiled by:
This should be compiled by::
make klog LDLIBS="-lcrypto -lcrypt -lkrb4 -lkeyutils"
And then run as:
And then run as::
./klog
Assuming it's successful, this adds a key of type RxRPC, named for the service
and cell, eg: "afs@<cellname>". This can be viewed with the keyctl program or
by cat'ing /proc/keys:
by cat'ing /proc/keys::
[root@andromeda ~]# keyctl show
Session Keyring
@ -232,20 +226,19 @@ socket), then the operations on the file will be made with key that was used to
open the file.
=====================
THE @SYS SUBSTITUTION
The @sys Substitution
=====================
The list of up to 16 @sys substitutions for the current network namespace can
be configured by writing a list to /proc/fs/afs/sysname:
be configured by writing a list to /proc/fs/afs/sysname::
[root@andromeda ~]# echo foo amd64_linux_26 >/proc/fs/afs/sysname
or cleared entirely by writing an empty list:
or cleared entirely by writing an empty list::
[root@andromeda ~]# echo >/proc/fs/afs/sysname
The current list for current network namespace can be retrieved by:
The current list for current network namespace can be retrieved by::
[root@andromeda ~]# cat /proc/fs/afs/sysname
foo

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@ -49,6 +49,7 @@ Documentation for filesystem implementations.
9p
adfs
affs
afs
autofs
fuse
overlayfs