From 8db7d16526debbca6bc7a32a57fd0378e48e37de Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Mon, 1 Nov 2021 07:46:52 +0200
Subject: [PATCH] geom_vfs: lock devvp in g_vfs_close()

It is needed for g_vfs_close() invalidating the buffers.  We rely on the
vnode lock for correctness.

Reported and tested by:	pho
Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D32761
---
 sys/geom/geom_vfs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sys/geom/geom_vfs.c b/sys/geom/geom_vfs.c
index 592062b8b12..9590fee1100 100644
--- a/sys/geom/geom_vfs.c
+++ b/sys/geom/geom_vfs.c
@@ -302,12 +302,16 @@ g_vfs_close(struct g_consumer *cp)
 {
 	struct g_geom *gp;
 	struct g_vfs_softc *sc;
+	struct vnode *vp;
 
 	g_topology_assert();
 
 	gp = cp->geom;
 	sc = gp->softc;
+	vp = cp->private;
+	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 	bufobj_invalbuf(sc->sc_bo, V_SAVE, 0, 0);
+	VOP_UNLOCK(vp);
 	sc->sc_bo->bo_private = cp->private;
 	gp->softc = NULL;
 	mtx_destroy(&sc->sc_mtx);