From 973b795b6453c7112d3dee9ca09906f7fbdfab31 Mon Sep 17 00:00:00 2001
From: Attilio Rao <attilio@FreeBSD.org>
Date: Mon, 19 Nov 2012 20:43:19 +0000
Subject: [PATCH] insmntque() is always called with the lock held in exclusive
 mode, then: - assume the lock is held in exclusive mode and remove a moot
 check   about the lock acquisition. - in the destructor remove !MPSAFE
 specific chunk.

Reviewed by:	kib
MFC after:	2 weeks
---
 sys/kern/vfs_subr.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 179b7f4aad30..f1a0d34c6c82 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1111,10 +1111,6 @@ insmntque_stddtr(struct vnode *vp, void *dtr_arg)
 
 	vp->v_data = NULL;
 	vp->v_op = &dead_vnodeops;
-	/* XXX non mp-safe fs may still call insmntque with vnode
-	   unlocked */
-	if (!VOP_ISLOCKED(vp))
-		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 	vgone(vp);
 	vput(vp);
 }
@@ -1126,7 +1122,6 @@ int
 insmntque1(struct vnode *vp, struct mount *mp,
 	void (*dtr)(struct vnode *, void *), void *dtr_arg)
 {
-	int locked;
 
 	KASSERT(vp->v_mount == NULL,
 		("insmntque: vnode already on per mount vnode list"));
@@ -1144,18 +1139,15 @@ insmntque1(struct vnode *vp, struct mount *mp,
 	 */
 	MNT_ILOCK(mp);
 	VI_LOCK(vp);
-	if ((mp->mnt_kern_flag & MNTK_NOINSMNTQ) != 0 &&
+	if (((mp->mnt_kern_flag & MNTK_NOINSMNTQ) != 0 &&
 	    ((mp->mnt_kern_flag & MNTK_UNMOUNTF) != 0 ||
-	     mp->mnt_nvnodelistsize == 0)) {
-		locked = VOP_ISLOCKED(vp);
-		if (!locked || (locked == LK_EXCLUSIVE &&
-		     (vp->v_vflag & VV_FORCEINSMQ) == 0)) {
-			VI_UNLOCK(vp);
-			MNT_IUNLOCK(mp);
-			if (dtr != NULL)
-				dtr(vp, dtr_arg);
-			return (EBUSY);
-		}
+	    mp->mnt_nvnodelistsize == 0)) &&
+	    (vp->v_vflag & VV_FORCEINSMQ) == 0) {
+		VI_UNLOCK(vp);
+		MNT_IUNLOCK(mp);
+		if (dtr != NULL)
+			dtr(vp, dtr_arg);
+		return (EBUSY);
 	}
 	vp->v_mount = mp;
 	MNT_REF(mp);