[Xen-devel] [PATCH v3] hotplug/Linux: add iscsi block hotplug script

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

This hotplug script has been tested with IET and NetBSD iSCSI targets,
without authentication.

This hotplug script will only work with PV guests not using pygrub.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxx>
---
Changes since v2:
 * Removed returns from functions, since we call fatal on error.
 * Removed checks for the return value of internal functions.
 * Use do_or_die or && and || in order to prevent using set +e/set -e.
Changes since v1:
 * Added an example in the script header to show the usage.
 * Changed shebang to use bash.
 * Replace type with command, for portability reasons.
 * Replace echo with fatal/log functions.
 * Include block-common.sh.
 * Prevent infinite loop when waitign for device to settle.
 * Only redirect stdout to /dev/null.
Changes due to 4.3 release freeze:
 * We can no longer provide a user/password, because they will be
   stored in xenstore "params" backend node, which can be read by the
   guest.
 * Only works with PV domains because we don't have a hook in libxl to
   pass the block device created by the script to Qemu.
 * Doesn't work with pygrub because we don't call the script until
   pygrub has already been executed, and even if we called it earlier
   we still need a hook in order to provide the right block device to
   pygrub.
Changes since v1:
 * Add -e to script shebang, and use 'set +e' if we know hotplug
   execution might fail.
---
 tools/hotplug/Linux/Makefile    |    1 +
 tools/hotplug/Linux/block-iscsi |  154 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 155 insertions(+), 0 deletions(-)
 create mode 100644 tools/hotplug/Linux/block-iscsi

diff --git a/tools/hotplug/Linux/Makefile b/tools/hotplug/Linux/Makefile
index 0605559..98c7738 100644
--- a/tools/hotplug/Linux/Makefile
+++ b/tools/hotplug/Linux/Makefile
@@ -21,6 +21,7 @@ XEN_SCRIPTS += blktap
 XEN_SCRIPTS += xen-hotplug-cleanup
 XEN_SCRIPTS += external-device-migrate
 XEN_SCRIPTS += vscsi
+XEN_SCRIPTS += block-iscsi
 XEN_SCRIPT_DATA = xen-script-common.sh locking.sh logging.sh
 XEN_SCRIPT_DATA += xen-hotplug-common.sh xen-network-common.sh vif-common.sh
 XEN_SCRIPT_DATA += block-common.sh
diff --git a/tools/hotplug/Linux/block-iscsi b/tools/hotplug/Linux/block-iscsi
new file mode 100644
index 0000000..8e36852
--- /dev/null
+++ b/tools/hotplug/Linux/block-iscsi
@@ -0,0 +1,154 @@
+#!/bin/bash -e
+#
+# Open-iSCSI Xen block device hotplug script
+#
+# Author Roger Pau Monnà <roger.pau@xxxxxxxxxx>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published
+# by the Free Software Foundation; version 2.1 only. with the special
+# exception on linking described in file LICENSE.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# Usage:
+#
+# Target should be specified using the following syntax:
+#
+# script=block-iscsi,vdev=xvda,target=iqn=<iqn>,portal=<portal IP>
+#
+# Portal address must be in IP format.
+#
+
+dir=$(dirname "$0")
+. "$dir/block-common.sh"
+
+remove_label()
+{
+    echo $1 | sed "s/^\("$2"\)//"
+}
+
+check_tools()
+{
+    if ! command -v iscsiadm > /dev/null 2>&1; then
+        fatal "Unable to find iscsiadm tool"
+    fi
+    if [ "$multipath" = "y" ] && ! command -v multipath > /dev/null 2>&1; then
+        fatal "Unable to find multipath"
+    fi
+}
+
+# Sets the following global variables based on the params field passed in as
+# a parameter: iqn, portal, auth_method, user, multipath, password
+parse_target()
+{
+    # set multipath default value
+    multipath="n"
+    for param in $(echo "$1" | tr "," "\n")
+    do
+        case $param in
+        iqn=*)
+            iqn=$(remove_label $param "iqn=")
+            ;;
+        portal=*)
+            portal=$(remove_label $param "portal=")
+            ;;
+        multipath=*)
+            multipath=$(remove_label $param "multipath=")
+            ;;
+        esac
+    done
+    if [ -z "$iqn" ] || [ -z "$portal" ]; then
+        fatal "iqn= and portal= are required parameters"
+    fi
+    if [ "$multipath" != "y" ] && [ "$multipath" != "n" ]; then
+        fatal "multipath valid values are y and n, $multipath not a valid 
value"
+    fi
+}
+
+# Sets $dev to point to the device associated with the value in iqn
+find_device()
+{
+    count=0
+    while [ ! -e /dev/disk/by-path/*"$iqn"-lun-0 ]; do
+        sleep 0.1
+        count=`expr $count + 1`
+        if [ count = 100 ]; then
+            # 10s timeout while waiting for iSCSI disk to settle
+            fatal "timeout waiting for iSCSI disk to settle"
+        fi
+    done
+    sddev=$(readlink -f /dev/disk/by-path/*"$iqn"-lun-0 || true)
+    if [ ! -b "$sddev" ]; then
+        fatal "Unable to find attached device path"
+    fi
+    if [ "$multipath" = "y" ]; then
+        mdev=$(multipath -ll "$sddev" | head -1 | awk '{ print $1}')
+        if [ ! -b /dev/mapper/"$mdev" ]; then
+            fatal "Unable to find attached device multipath"
+        fi
+        dev="/dev/mapper/$mdev"
+    else
+        dev="$sddev"
+    fi
+}
+
+# Attaches the target $iqn in $portal and sets $dev to point to the
+# multipath device
+attach()
+{
+    do_or_die iscsiadm -m node --targetname "$iqn" -p "$portal" --login > 
/dev/null
+    find_device
+}
+
+# Discovers targets in $portal and checks that $iqn is one of those targets
+# Also sets the auth parameters to attach the device
+prepare()
+{
+    # Check if target is already opened
+    iscsiadm -m session 2>&1 | grep -q "$iqn" && fatal "Device already opened"
+    # Discover portal targets
+    iscsiadm -m discovery -t st -p $portal 2>&1 | grep -q "$iqn" || \
+        fatal "No matching target iqn found"
+}
+
+# Attaches the device and writes xenstore backend entries to connect
+# the device
+add()
+{
+    attach
+    write_dev $dev
+}
+
+# Disconnects the device
+remove()
+{
+    find_device
+    do_or_die iscsiadm -m node --targetname "$iqn" -p "$portal" --logout > 
/dev/null
+}
+
+command=$1
+target=$(xenstore-read $XENBUS_PATH/params || true)
+if [ -z "$target" ]; then
+    fatal "No information about the target"
+fi
+
+parse_target "$target"
+
+check_tools || exit 1
+
+case $command in
+add)
+    prepare
+    add
+    ;;
+remove)
+    remove
+    ;;
+*)
+    exit 1
+    ;;
+esac
-- 
1.7.7.5 (Apple Git-26)


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