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authorMauro Carvalho Chehab <mchehab+samsung@kernel.org>2019-06-27 18:59:40 +0300
committerMauro Carvalho Chehab <mchehab+samsung@kernel.org>2019-07-15 17:03:02 +0300
commit83bbf6e103544d65f17f4b2ccea1c6a51c0b0769 (patch)
tree9f37eb8ea225fc60312ba26b43522c420634da53 /Documentation/admin-guide/aoe
parentdf1b7ce784c220373d202ea9f8bc0c424f2c9f7c (diff)
downloadlinux-83bbf6e103544d65f17f4b2ccea1c6a51c0b0769.tar.xz
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>
Diffstat (limited to 'Documentation/admin-guide/aoe')
-rw-r--r--Documentation/admin-guide/aoe/aoe.rst150
-rw-r--r--Documentation/admin-guide/aoe/autoload.sh17
-rw-r--r--Documentation/admin-guide/aoe/examples.rst23
-rw-r--r--Documentation/admin-guide/aoe/index.rst17
-rw-r--r--Documentation/admin-guide/aoe/status.sh30
-rw-r--r--Documentation/admin-guide/aoe/todo.rst17
-rw-r--r--Documentation/admin-guide/aoe/udev-install.sh33
-rw-r--r--Documentation/admin-guide/aoe/udev.txt26
8 files changed, 313 insertions, 0 deletions
diff --git a/Documentation/admin-guide/aoe/aoe.rst b/Documentation/admin-guide/aoe/aoe.rst
new file mode 100644
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"