[Cluster-devel] [GFS2 PATCH] gfs2-utils: Fix hang on withdraw

[Abhijith Das]

Issuing a withdraw on a gfs2 filesystem causes a hang. When
gfs_controld was removed, the userspace functionality that
completes a withdraw operation went away. This causes gfs2
kernel to hang waiting for a withdraw completion ack from
userspace.

This patchset introduces a uevent-based shell script to do
the job that gfs_controld used to do on withdraw. An 'offline'
uevent triggers the execution of this script. This script
suspends the device associated with the filesystem and signals
a completed withdraw to the kernel.

Resolves: rhbz#1225634
Signed-off-by: Abhi Das <adas at redhat.com>
---
 gfs2/scripts/82-gfs2-withdraw.rules |  2 ++
 gfs2/scripts/gfs2_wd_udev.sh        | 30 ++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)
 create mode 100644 gfs2/scripts/82-gfs2-withdraw.rules
 create mode 100755 gfs2/scripts/gfs2_wd_udev.sh

diff --git a/gfs2/scripts/82-gfs2-withdraw.rules b/gfs2/scripts/82-gfs2-withdraw.rules
new file mode 100644
index 0000000..c1ab02b
--- /dev/null
+++ b/gfs2/scripts/82-gfs2-withdraw.rules
@@ -0,0 +1,2 @@
+SUBSYSTEM=="gfs2", ACTION=="offline", RUN+="/bin/sh /sbin/gfs2_wd_udev.sh"
+
diff --git a/gfs2/scripts/gfs2_wd_udev.sh b/gfs2/scripts/gfs2_wd_udev.sh
new file mode 100755
index 0000000..ac3ce35
--- /dev/null
+++ b/gfs2/scripts/gfs2_wd_udev.sh
@@ -0,0 +1,30 @@
+#!/bin/sh
+#
+# Do not run this script manually. This script is called by udev on a gfs2
+# withdraw uevent and is used to complete the withdraw action and notify the
+# kernel.
+#
+
+# Sanity checks
+if [ "$SUBSYSTEM" != "gfs2" ] || [ "$LOCKPROTO" != "lock_dlm" ] ||
+       [ -z "$DEVPATH" ] || [ "$ACTION" != "offline" ]
+then
+    exit 1 # Nothing to do here
+fi
+
+# Try and suspend the device
+SYSFS_TOPDIR="/sys"$DEVPATH
+DM_NAME=$(cat "$SYSFS_TOPDIR/device/dm/name")
+DM_DEV="/dev/mapper/"$DM_NAME
+
+if [ -z "$DM_DEV" ]
+then
+    /usr/bin/dmsetup suspend $DM_DEV
+fi
+
+# Signal completion of withdraw
+WD_ACK="$SYSFS_TOPDIR/lock_module/withdraw"
+if [ -f "$WD_ACK" ]
+then
+    echo "1" > $WD_ACK
+fi
-- 
2.4.3