docs: aoe: add it to the driver-api book

Those files belong to the admin guide, so add them.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Justin Sanders <justin@coraid.com>

9 files changed, 314 insertions, 0 deletions

diff --git a/Documentation/admin-guide/aoe/aoe.rst b/Documentation/admin-guide/aoe/aoe.rst
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index 000000000000..a05e751363a0
--- /dev/null
+++ b/Documentation/admin-guide/aoe/aoe.rst
@@ -0,0 +1,150 @@
+Introduction
+============
+
+ATA over Ethernet is a network protocol that provides simple access to
+block storage on the LAN.
+
+  http://support.coraid.com/documents/AoEr11.txt
+
+The EtherDrive (R) HOWTO for 2.6 and 3.x kernels is found at ...
+
+  http://support.coraid.com/support/linux/EtherDrive-2.6-HOWTO.html
+
+It has many tips and hints!  Please see, especially, recommended
+tunings for virtual memory:
+
+  http://support.coraid.com/support/linux/EtherDrive-2.6-HOWTO-5.html#ss5.19
+
+The aoetools are userland programs that are designed to work with this
+driver.  The aoetools are on sourceforge.
+
+  http://aoetools.sourceforge.net/
+
+The scripts in this Documentation/admin-guide/aoe directory are intended to
+document the use of the driver and are not necessary if you install
+the aoetools.
+
+
+Creating Device Nodes
+=====================
+
+  Users of udev should find the block device nodes created
+  automatically, but to create all the necessary device nodes, use the
+  udev configuration rules provided in udev.txt (in this directory).
+
+  There is a udev-install.sh script that shows how to install these
+  rules on your system.
+
+  There is also an autoload script that shows how to edit
+  /etc/modprobe.d/aoe.conf to ensure that the aoe module is loaded when
+  necessary.  Preloading the aoe module is preferable to autoloading,
+  however, because AoE discovery takes a few seconds.  It can be
+  confusing when an AoE device is not present the first time the a
+  command is run but appears a second later.
+
+Using Device Nodes
+==================
+
+  "cat /dev/etherd/err" blocks, waiting for error diagnostic output,
+  like any retransmitted packets.
+
+  "echo eth2 eth4 > /dev/etherd/interfaces" tells the aoe driver to
+  limit ATA over Ethernet traffic to eth2 and eth4.  AoE traffic from
+  untrusted networks should be ignored as a matter of security.  See
+  also the aoe_iflist driver option described below.
+
+  "echo > /dev/etherd/discover" tells the driver to find out what AoE
+  devices are available.
+
+  In the future these character devices may disappear and be replaced
+  by sysfs counterparts.  Using the commands in aoetools insulates
+  users from these implementation details.
+
+  The block devices are named like this::
+
+	e{shelf}.{slot}
+	e{shelf}.{slot}p{part}
+
+  ... so that "e0.2" is the third blade from the left (slot 2) in the
+  first shelf (shelf address zero).  That's the whole disk.  The first
+  partition on that disk would be "e0.2p1".
+
+Using sysfs
+===========
+
+  Each aoe block device in /sys/block has the extra attributes of
+  state, mac, and netif.  The state attribute is "up" when the device
+  is ready for I/O and "down" if detected but unusable.  The
+  "down,closewait" state shows that the device is still open and
+  cannot come up again until it has been closed.
+
+  The mac attribute is the ethernet address of the remote AoE device.
+  The netif attribute is the network interface on the localhost
+  through which we are communicating with the remote AoE device.
+
+  There is a script in this directory that formats this information in
+  a convenient way.  Users with aoetools should use the aoe-stat
+  command::
+
+    root@makki root# sh Documentation/admin-guide/aoe/status.sh
+       e10.0            eth3              up
+       e10.1            eth3              up
+       e10.2            eth3              up
+       e10.3            eth3              up
+       e10.4            eth3              up
+       e10.5            eth3              up
+       e10.6            eth3              up
+       e10.7            eth3              up
+       e10.8            eth3              up
+       e10.9            eth3              up
+        e4.0            eth1              up
+        e4.1            eth1              up
+        e4.2            eth1              up
+        e4.3            eth1              up
+        e4.4            eth1              up
+        e4.5            eth1              up
+        e4.6            eth1              up
+        e4.7            eth1              up
+        e4.8            eth1              up
+        e4.9            eth1              up
+
+  Use /sys/module/aoe/parameters/aoe_iflist (or better, the driver
+  option discussed below) instead of /dev/etherd/interfaces to limit
+  AoE traffic to the network interfaces in the given
+  whitespace-separated list.  Unlike the old character device, the
+  sysfs entry can be read from as well as written to.
+
+  It's helpful to trigger discovery after setting the list of allowed
+  interfaces.  The aoetools package provides an aoe-discover script
+  for this purpose.  You can also directly use the
+  /dev/etherd/discover special file described above.
+
+Driver Options
+==============
+
+  There is a boot option for the built-in aoe driver and a
+  corresponding module parameter, aoe_iflist.  Without this option,
+  all network interfaces may be used for ATA over Ethernet.  Here is a
+  usage example for the module parameter::
+
+    modprobe aoe_iflist="eth1 eth3"
+
+  The aoe_deadsecs module parameter determines the maximum number of
+  seconds that the driver will wait for an AoE device to provide a
+  response to an AoE command.  After aoe_deadsecs seconds have
+  elapsed, the AoE device will be marked as "down".  A value of zero
+  is supported for testing purposes and makes the aoe driver keep
+  trying AoE commands forever.
+
+  The aoe_maxout module parameter has a default of 128.  This is the
+  maximum number of unresponded packets that will be sent to an AoE
+  target at one time.
+
+  The aoe_dyndevs module parameter defaults to 1, meaning that the
+  driver will assign a block device minor number to a discovered AoE
+  target based on the order of its discovery.  With dynamic minor
+  device numbers in use, a greater range of AoE shelf and slot
+  addresses can be supported.  Users with udev will never have to
+  think about minor numbers.  Using aoe_dyndevs=0 allows device nodes
+  to be pre-created using a static minor-number scheme with the
+  aoe-mkshelf script in the aoetools.
diff --git a/Documentation/admin-guide/aoe/autoload.sh b/Documentation/admin-guide/aoe/autoload.sh
new file mode 100644
index 000000000000..815dff4691c9
--- /dev/null
+++ b/Documentation/admin-guide/aoe/autoload.sh
@@ -0,0 +1,17 @@
+#!/bin/sh
+# set aoe to autoload by installing the
+# aliases in /etc/modprobe.d/
+
+f=/etc/modprobe.d/aoe.conf
+
+if test ! -r $f || test ! -w $f; then
+	echo "cannot configure $f for module autoloading" 1>&2
+	exit 1
+fi
+
+grep major-152 $f >/dev/null
+if [ $? = 1 ]; then
+	echo alias block-major-152 aoe >> $f
+	echo alias char-major-152 aoe >> $f
+fi
+
diff --git a/Documentation/admin-guide/aoe/examples.rst b/Documentation/admin-guide/aoe/examples.rst
new file mode 100644
index 000000000000..91f3198e52c1
--- /dev/null
+++ b/Documentation/admin-guide/aoe/examples.rst
@@ -0,0 +1,23 @@
+Example of udev rules
+---------------------
+
+ .. include:: udev.txt
+    :literal:
+
+Example of udev install rules script
+------------------------------------
+
+ .. literalinclude:: udev-install.sh
+    :language: shell
+
+Example script to get status
+----------------------------
+
+ .. literalinclude:: status.sh
+    :language: shell
+
+Example of AoE autoload script
+------------------------------
+
+ .. literalinclude:: autoload.sh
+    :language: shell
diff --git a/Documentation/admin-guide/aoe/index.rst b/Documentation/admin-guide/aoe/index.rst
new file mode 100644
index 000000000000..d71c5df15922
--- /dev/null
+++ b/Documentation/admin-guide/aoe/index.rst
@@ -0,0 +1,17 @@
+=======================
+ATA over Ethernet (AoE)
+=======================
+
+.. toctree::
+    :maxdepth: 1
+
+    aoe
+    todo
+    examples
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`
diff --git a/Documentation/admin-guide/aoe/status.sh b/Documentation/admin-guide/aoe/status.sh
new file mode 100644
index 000000000000..eeec7baae57a
--- /dev/null
+++ b/Documentation/admin-guide/aoe/status.sh
@@ -0,0 +1,30 @@
+#! /bin/sh
+# collate and present sysfs information about AoE storage
+#
+# A more complete version of this script is aoe-stat, in the
+# aoetools.
+
+set -e
+format="%8s\t%8s\t%8s\n"
+me=`basename $0`
+sysd=${sysfs_dir:-/sys}
+
+# printf "$format" device mac netif state
+
+# Suse 9.1 Pro doesn't put /sys in /etc/mtab
+#test -z "`mount | grep sysfs`" && {
+test ! -d "$sysd/block" && {
+	echo "$me Error: sysfs is not mounted" 1>&2
+	exit 1
+}
+
+for d in `ls -d $sysd/block/etherd* 2>/dev/null | grep -v p` end; do
+	# maybe ls comes up empty, so we use "end"
+	test $d = end && continue
+
+	dev=`echo "$d" | sed 's/.*!//'`
+	printf "$format" \
+		"$dev" \
+		"`cat \"$d/netif\"`" \
+		"`cat \"$d/state\"`"
+done | sort
diff --git a/Documentation/admin-guide/aoe/todo.rst b/Documentation/admin-guide/aoe/todo.rst
new file mode 100644
index 000000000000..dea8db5a33e1
--- /dev/null
+++ b/Documentation/admin-guide/aoe/todo.rst
@@ -0,0 +1,17 @@
+TODO
+====
+
+There is a potential for deadlock when allocating a struct sk_buff for
+data that needs to be written out to aoe storage.  If the data is
+being written from a dirty page in order to free that page, and if
+there are no other pages available, then deadlock may occur when a
+free page is needed for the sk_buff allocation.  This situation has
+not been observed, but it would be nice to eliminate any potential for
+deadlock under memory pressure.
+
+Because ATA over Ethernet is not fragmented by the kernel's IP code,
+the destructor member of the struct sk_buff is available to the aoe
+driver.  By using a mempool for allocating all but the first few
+sk_buffs, and by registering a destructor, we should be able to
+efficiently allocate sk_buffs without introducing any potential for
+deadlock.
diff --git a/Documentation/admin-guide/aoe/udev-install.sh b/Documentation/admin-guide/aoe/udev-install.sh
new file mode 100644
index 000000000000..15e86f58c036
--- /dev/null
+++ b/Documentation/admin-guide/aoe/udev-install.sh
@@ -0,0 +1,33 @@
+# install the aoe-specific udev rules from udev.txt into 
+# the system's udev configuration
+# 
+
+me="`basename $0`"
+
+# find udev.conf, often /etc/udev/udev.conf
+# (or environment can specify where to find udev.conf)
+#
+if test -z "$conf"; then
+	if test -r /etc/udev/udev.conf; then
+		conf=/etc/udev/udev.conf
+	else
+		conf="`find /etc -type f -name udev.conf 2> /dev/null`"
+		if test -z "$conf" || test ! -r "$conf"; then
+			echo "$me Error: no udev.conf found" 1>&2
+			exit 1
+		fi
+	fi
+fi
+
+# find the directory where udev rules are stored, often
+# /etc/udev/rules.d
+#
+rules_d="`sed -n '/^udev_rules=/{ s!udev_rules=!!; s!\"!!g; p; }' $conf`"
+if test -z "$rules_d" ; then
+	rules_d=/etc/udev/rules.d
+fi
+if test ! -d "$rules_d"; then
+	echo "$me Error: cannot find udev rules directory" 1>&2
+	exit 1
+fi
+sh -xc "cp `dirname $0`/udev.txt $rules_d/60-aoe.rules"
diff --git a/Documentation/admin-guide/aoe/udev.txt b/Documentation/admin-guide/aoe/udev.txt
new file mode 100644
index 000000000000..5fb756466bc7
--- /dev/null
+++ b/Documentation/admin-guide/aoe/udev.txt
@@ -0,0 +1,26 @@
+# These rules tell udev what device nodes to create for aoe support.
+# They may be installed along the following lines.  Check the section
+# 8 udev manpage to see whether your udev supports SUBSYSTEM, and
+# whether it uses one or two equal signs for SUBSYSTEM and KERNEL.
+# 
+#   ecashin@makki ~$ su
+#   Password:
+#   bash# find /etc -type f -name udev.conf
+#   /etc/udev/udev.conf
+#   bash# grep udev_rules= /etc/udev/udev.conf
+#   udev_rules="/etc/udev/rules.d/"
+#   bash# ls /etc/udev/rules.d/
+#   10-wacom.rules  50-udev.rules
+#   bash# cp /path/to/linux/Documentation/admin-guide/aoe/udev.txt \
+#           /etc/udev/rules.d/60-aoe.rules
+#  
+
+# aoe char devices
+SUBSYSTEM=="aoe", KERNEL=="discover",	NAME="etherd/%k", GROUP="disk", MODE="0220"
+SUBSYSTEM=="aoe", KERNEL=="err",	NAME="etherd/%k", GROUP="disk", MODE="0440"
+SUBSYSTEM=="aoe", KERNEL=="interfaces",	NAME="etherd/%k", GROUP="disk", MODE="0220"
+SUBSYSTEM=="aoe", KERNEL=="revalidate",	NAME="etherd/%k", GROUP="disk", MODE="0220"
+SUBSYSTEM=="aoe", KERNEL=="flush",	NAME="etherd/%k", GROUP="disk", MODE="0220"
+
+# aoe block devices     
+KERNEL=="etherd*",       GROUP="disk"
diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst
index 9228fbf5ce4e..1f0d9b939311 100644
--- a/Documentation/admin-guide/index.rst
+++ b/Documentation/admin-guide/index.rst
@@ -83,6 +83,7 @@ configure specific aspects of kernel behavior to your liking.
    namespaces/index
    perf-security
    acpi/index
+   aoe/index
    device-mapper/index
    laptops/index