From e37dfd3d2b204c08d0a5296c379df78cb30d70f0 Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Sun, 19 Jun 2016 18:29:43 +0000
Subject: [PATCH] Do not access NFS data for reclaimed vnode.

Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Approved by:	re (delphij)
---
 sys/fs/nfsclient/nfs_clvnops.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/sys/fs/nfsclient/nfs_clvnops.c b/sys/fs/nfsclient/nfs_clvnops.c
index 2a8afa9d542..5799d0bd6f3 100644
--- a/sys/fs/nfsclient/nfs_clvnops.c
+++ b/sys/fs/nfsclient/nfs_clvnops.c
@@ -3097,10 +3097,14 @@ nfs_advlock(struct vop_advlock_args *ap)
 			}
 		}
 		if (error == 0 && ap->a_op == F_SETLK) {
-			/* Mark that a file lock has been acquired. */
-			mtx_lock(&np->n_mtx);
-			np->n_flag |= NHASBEENLOCKED;
-			mtx_unlock(&np->n_mtx);
+			error = NFSVOPLOCK(vp, LK_SHARED);
+			if (error == 0) {
+				/* Mark that a file lock has been acquired. */
+				mtx_lock(&np->n_mtx);
+				np->n_flag |= NHASBEENLOCKED;
+				mtx_unlock(&np->n_mtx);
+				NFSVOPUNLOCK(vp, 0);
+			}
 		}
 	}
 	return (error);