From 1d7f30a13e156ee1a359f6f59a4ff994eac1ca90 Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Fri, 12 Nov 2021 15:55:54 +0100
Subject: [mount-store] Take greater care where the .notmounted flag is written

While the task manager should make sure only one invocation if
mount-store is running, add a few extra checks whether a mount-point is
pulled under our feet, or mounted when we don't expect it.
This includes making sure dmsd is not accessing the share while we're
trying to manipulate it.
---
 scripts/mount-store                                   | 19 ++++++++++++++++++-
 .../org/openslx/taskmanager/tasks/MountVmStore.java   |  2 +-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/scripts/mount-store b/scripts/mount-store
index 3cff451..6a21bf6 100755
--- a/scripts/mount-store
+++ b/scripts/mount-store
@@ -125,6 +125,12 @@ disable_nfs_export () {
 	fi
 }
 
+start_dmsd () {
+	if "$DMSD_WAS_RUNNING"; then
+		systemctl --no-block start dmsd.service
+	fi
+}
+
 # Quick safty measure -- if any local FS is mounted, do nothing and print warning if different type is requested
 CURRENT_TYPE="$( awk -v DEST="$DEST" '$2 == DEST {print $3}' /proc/mounts )"
 if [ -n "$CURRENT_TYPE" ] && ! [[ "$CURRENT_TYPE" == nfs* || "$CURRENT_TYPE" == cifs* ]]; then
@@ -148,8 +154,10 @@ systemctl stop dnbd3-server.service
 # Already mounted?
 TRIES=0
 NFS_WAS_RUNNING=false
+DMSD_WAS_RUNNING=false
 systemctl is-active -q nfs-kernel-server.service && NFS_WAS_RUNNING=true
-while awk '{print $2}' "/proc/mounts" | grep -Fxq "${DEST}"; do
+systemctl is-active -q dmsd.service && DMSD_WAS_RUNNING=true
+while mountpoint "${DEST}"; do
 	echo "Trying to unmount '$DEST'..."
 	systemctl stop nfs-kernel-server.service
 	if [ "$TRIES" -gt 5 ]; then
@@ -172,6 +180,7 @@ while awk '{print $2}' "/proc/mounts" | grep -Fxq "${DEST}"; do
 		RET=$?
 	fi
 	[ "$RET" = 0 ] && break
+	systemctl stop dmsd.service
 	sleep 1
 	TRIES=$(( TRIES + 1 ))
 done
@@ -194,6 +203,7 @@ fi
 if [[ "${SOURCE}" == "null" ]]; then
 	prepare_storage "local"
 	systemctl --no-block start dnbd3-server.service
+	start_dmsd
 	enable_nfs_export
 	echo "Success. Now using internal storage."
 	exit 0
@@ -203,6 +213,11 @@ fi
 
 disable_nfs_export
 
+if mountpoint "${DEST}"; then
+	echo "**** Something was mounted to $DEST in the meantime. Aborting ****"
+	# Use the "nothing changed" exit code, as another concurrent invocation has changed stuff, apparently
+	exit 99
+fi
 touch "${FLAG}"
 
 if [[ "${SOURCE}" == "unknown" ]]; then
@@ -225,6 +240,7 @@ exec_mount () {
 	echo "Mount succeeded, checking write permissions...."
 	prepare_storage "$fstype"
 	RET=$?
+	mountpoint "$DEST" && rm -f -- "$FLAG"
 	[ "$RET" -eq "0" ] && return 0
 	umount -v "$DEST" || umount -v -f -l "$DEST"
 	return "$RET"
@@ -323,6 +339,7 @@ if [ "$RET" = "0" ]; then
 	echo "-- Share mounted successfully!  --"
 	echo "----------------------------------"
 	systemctl --no-block start dnbd3-server.service
+	start_dmsd
 fi
 
 exit "$RET"
diff --git a/src/main/java/org/openslx/taskmanager/tasks/MountVmStore.java b/src/main/java/org/openslx/taskmanager/tasks/MountVmStore.java
index d0530cc..791fcad 100644
--- a/src/main/java/org/openslx/taskmanager/tasks/MountVmStore.java
+++ b/src/main/java/org/openslx/taskmanager/tasks/MountVmStore.java
@@ -47,7 +47,7 @@ public class MountVmStore extends SystemCommandTask
 	@Override
 	protected String[] initCommandLine()
 	{
-		if ( !isRunning.compareAndSet( null, this ) ) {
+		while ( !isRunning.compareAndSet( null, this ) ) {
 			MountVmStore current = isRunning.get();
 			if ( current != null ) {
 				if ( current.equals( this ) ) {
-- 
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