FSExecutor fails to detect auto mounted storage

If kup-daemon is started when my NAS is offline, it fails to detect when it comes back up. I use systemd auto mounting.

My plan's destination path is: /share/nas/home/foo.bup

/etc/fstab

//nas0/homes/<some> /share/nas/home  cifs user,noauto,nofail,x-systemd.automount,x-systemd.device-timeout=10,x-systemd.idle-timeout=0,<somemoreopts> 0 0

/proc/mounts | grep nas/home before mount

systemd-1 /share/nas/home autofs <mountopts> 0 0

/proc/mounts | grep nas/home after starting NAS and ls /share/nas/home

systemd-1 /share/nas/home autofs <mountopts> 0 0
//nas0/homes/<some> /share/nas/home cifs <mountopts> 0 0

MountWatcher correctly detects the appearance of the mount and calls FSExecutor::checkMountPoints. There, mWatchedParentDir is /share/nas which is "incorrect" as it should be /share/nas/home.

	QDir lDir(mDestinationPath);
	if(!lDir.exists()) {
		// Destination doesn't exist, find nearest existing parent folder and
		// watch that for dirty or deleted
		if(mDirWatch->contains(mDestinationPath)) {
			mDirWatch->removeDir(mDestinationPath);
		}

		QString lExisting = mDestinationPath;
		do {
			lExisting += QStringLiteral("/..");
			lDir = QDir(QDir::cleanPath(lExisting));
		} while(!lDir.exists());
		lExisting = lDir.canonicalPath();

The issue is that lDir.exists() returns false for the actual mount point /share/nas/home when it shouldn't.

Yet various checks behave differently. [ -d /share/nas/home ] && echo ok says 'ok' ls,stat(1),opendir(3) error with "no such device".

Luckily stat(3) seems to work fine. So i propose to use that, at least for the parent-dir-detection.