[Cluster-devel] [GFS2 PATCH v2] 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>
---
 README.build                        |  9 +++++++++
 gfs2/scripts/82-gfs2-withdraw.rules |  2 ++
 gfs2/scripts/Makefile.am            |  5 +++++
 gfs2/scripts/gfs2_wd_udev.sh        | 30 ++++++++++++++++++++++++++++++
 4 files changed, 46 insertions(+)
 create mode 100644 gfs2/scripts/82-gfs2-withdraw.rules
 create mode 100755 gfs2/scripts/gfs2_wd_udev.sh

diff --git a/README.build b/README.build
index f4ebe53..6487bae 100644
--- a/README.build
+++ b/README.build
@@ -29,5 +29,14 @@ To install gfs2-utils, run:
 
     make install
 
+The following scripts (located in gfs2/scripts) are used to complete
+the userland portion of the gfs2 withdraw feature using uevents. They
+are not installed by 'make install' and need to be installed manually
+or during rpm installation to the corresponding locations.
+
+	82-gfs2-withdraw.rules in /etc/udev/rules.d/
+	gfs2_wd_udev.sh        in /usr/sbin/
+
 See also doc/README.contributing for details on submitting patches and
 doc/README.tests for more details regarding the test suite.
+
diff --git a/gfs2/scripts/82-gfs2-withdraw.rules b/gfs2/scripts/82-gfs2-withdraw.rules
new file mode 100644
index 0000000..2228615
--- /dev/null
+++ b/gfs2/scripts/82-gfs2-withdraw.rules
@@ -0,0 +1,2 @@
+SUBSYSTEM=="gfs2", ACTION=="offline", RUN+="/bin/sh /usr/sbin/gfs2_wd_udev.sh"
+
diff --git a/gfs2/scripts/Makefile.am b/gfs2/scripts/Makefile.am
index 62fb2fe..dde906f 100644
--- a/gfs2/scripts/Makefile.am
+++ b/gfs2/scripts/Makefile.am
@@ -3,3 +3,8 @@ MAINTAINERCLEANFILES = Makefile.in
 dist_sbin_SCRIPTS = \
 	gfs2_lockcapture \
 	gfs2_trace
+
+noinst_SCRIPTS = \
+	82-gfs2-withdraw.rules \
+	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