Xen devel - May 2013 - [PATCH v3] hotplug/Linux: add iscsi block hotplug script

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 Monné <roger.pau@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <ian.jackson@citrix.com>
---
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 Monné <roger.pau@citrix.com>
+#
+# 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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Roger Pau Monne writes ("[PATCH v3] hotplug/Linux: add iscsi block hotplug
script"):
> This hotplug script has been tested with IET and NetBSD iSCSI targets,
> without authentication.
This looks plausible to me.  I think it''s low-risk and would warrant a
freeze exception.

Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>


ian.

On Tue, May 7, 2013 at 6:31 PM, Ian Jackson <Ian.Jackson@eu.citrix.com>
wrote:
> Roger Pau Monne writes ("[PATCH v3] hotplug/Linux: add iscsi block
hotplug script"):
>> This hotplug script has been tested with IET and NetBSD iSCSI targets,
>> without authentication.
>
> This looks plausible to me.  I think it''s low-risk and would
warrant a
> freeze exception.
>
> Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Yes, I think based on the timing of the patches posted, and the (low)
risk to breaking existing functionality:

Acked-by: George Dunlap <george.dunlap@eu.citriix.com>

On Wed, 2013-05-08 at 11:28 +0100, George Dunlap wrote:
> On Tue, May 7, 2013 at 6:31 PM, Ian Jackson
<Ian.Jackson@eu.citrix.com> wrote:
> > Roger Pau Monne writes ("[PATCH v3] hotplug/Linux: add iscsi
block hotplug script"):
> >> This hotplug script has been tested with IET and NetBSD iSCSI
targets,
> >> without authentication.
> >
> > This looks plausible to me.  I think it''s low-risk and would
warrant a
> > freeze exception.
> >
> > Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
> 
> Yes, I think based on the timing of the patches posted, and the (low)
> risk to breaking existing functionality:
> 
> Acked-by: George Dunlap <george.dunlap@eu.citriix.com>
Applied, thanks.