From e9eb5810438c7de713a45f43af227798a6b5ec2f Mon Sep 17 00:00:00 2001
From: Martin Schwenke <mschwenke@ddn.com>
Date: Fri, 10 May 2024 18:00:18 +1000
Subject: [PATCH] ctdb-scripts: Protect against races when starting grace
 period

While the PID check is worth it in relevant cases, NFS-Ganesha still
might go away after the check.  Unfortunately, neither grace command
fails an indicative exit code, so invent one by checking error
messages.  This can then be converted to success by the caller.

Signed-off-by: Martin Schwenke <mschwenke@ddn.com>
Reviewed-by: Volker Lendecke <vl@samba.org>

Autobuild-User(master): Volker Lendecke <vl@samba.org>
Autobuild-Date(master): Thu May 30 12:50:01 UTC 2024 on atb-devel-224
---
 ctdb/doc/examples/nfs-ganesha-callout | 39 ++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 4 deletions(-)

diff --git a/ctdb/doc/examples/nfs-ganesha-callout b/ctdb/doc/examples/nfs-ganesha-callout
index b0017d6cc10..8b7df88456e 100755
--- a/ctdb/doc/examples/nfs-ganesha-callout
+++ b/ctdb/doc/examples/nfs-ganesha-callout
@@ -272,13 +272,34 @@ grace_period()
 {
 	_arg="$1"
 
+	_gp_status=0
 	if [ -x "/usr/bin/grace_period" ]; then
-		/usr/bin/grace_period "$_arg"
+		_out=$(/usr/bin/grace_period "$_arg" 2>&1) ||
+			_gp_status=$?
+		_down_msg="Error: Can't talk to ganesha service on d-bus"
 	else
-		dbus-send --print-reply --system --dest=org.ganesha.nfsd \
+		_out=$(dbus-send \
+			--print-reply --system --dest=org.ganesha.nfsd \
 			/org/ganesha/nfsd/admin org.ganesha.nfsd.admin.grace \
-			string:"$_arg"
+			string:"$_arg" 2>&1) ||
+			_gp_status=$?
+		_down_msg="Error org.freedesktop.DBus.Error.ServiceUnknown"
 	fi
+
+	if [ -n "$_out" ]; then
+		echo "$_out"
+	fi
+
+	if [ $_gp_status -ne 0 ]; then
+		# If $_out contains $_down_msg then NFS-Ganesha is
+		# either down or is starting, so will be in grace
+		# anyway.
+		if [ "${_out#*"${_down_msg}"}" != "$_out" ]; then
+			return 3 # ESRCH - No such process
+		fi
+	fi
+
+	return $_gp_status
 }
 
 grace_period_if_running()
@@ -290,7 +311,17 @@ grace_period_if_running()
 		return 0
 	fi
 
-	grace_period "$_arg"
+	_status=0
+	grace_period "$_arg" || _status=$?
+	case $_status in
+	3)
+		# Convert to success
+		return 0
+		;;
+	*)
+		return $_status
+		;;
+	esac
 }
 
 nfs_startipreallocate()
-- 
2.47.3