diff --git a/sys/cam/ctl/ctl_backend_block.c b/sys/cam/ctl/ctl_backend_block.c
--- a/sys/cam/ctl/ctl_backend_block.c
+++ b/sys/cam/ctl/ctl_backend_block.c
@@ -588,7 +588,7 @@
 {
 	union ctl_io *io = beio->io;
 	struct mount *mountpoint;
-	int error, lock_flags;
+	int error;
 
 	DPRINTF("entered\n");
 
@@ -597,12 +597,8 @@
 
 	(void) vn_start_write(be_lun->vn, &mountpoint, V_WAIT);
 
-	if (MNT_SHARED_WRITES(mountpoint) ||
-	    ((mountpoint == NULL) && MNT_SHARED_WRITES(be_lun->vn->v_mount)))
-		lock_flags = LK_SHARED;
-	else
-		lock_flags = LK_EXCLUSIVE;
-	vn_lock(be_lun->vn, lock_flags | LK_RETRY);
+	vn_lock(be_lun->vn, vn_lktype_write(mountpoint, be_lun->vn) |
+	    LK_RETRY);
 	error = VOP_FSYNC(be_lun->vn, beio->io_arg ? MNT_NOWAIT : MNT_WAIT,
 	    curthread);
 	VOP_UNLOCK(be_lun->vn);
@@ -722,16 +718,10 @@
 		}
 	} else {
 		struct mount *mountpoint;
-		int lock_flags;
 
 		(void)vn_start_write(be_lun->vn, &mountpoint, V_WAIT);
-
-		if (MNT_SHARED_WRITES(mountpoint) || ((mountpoint == NULL)
-		  && MNT_SHARED_WRITES(be_lun->vn->v_mount)))
-			lock_flags = LK_SHARED;
-		else
-			lock_flags = LK_EXCLUSIVE;
-		vn_lock(be_lun->vn, lock_flags | LK_RETRY);
+		vn_lock(be_lun->vn, vn_lktype_write(mountpoint,
+		    be_lun->vn) | LK_RETRY);
 
 		/*
 		 * UFS pays attention to IO_DIRECT for writes.  The write
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -3517,7 +3517,7 @@
 	struct vnode *vp;
 	struct mount *mp;
 	struct file *fp;
-	int error, lock_flags;
+	int error;
 
 	AUDIT_ARG_FD(fd);
 	error = getvnode(td, fd, &cap_fsync_rights, &fp);
@@ -3532,13 +3532,7 @@
 	error = vn_start_write(vp, &mp, V_WAIT | PCATCH);
 	if (error != 0)
 		goto drop;
-	if (MNT_SHARED_WRITES(mp) ||
-	    ((mp == NULL) && MNT_SHARED_WRITES(vp->v_mount))) {
-		lock_flags = LK_SHARED;
-	} else {
-		lock_flags = LK_EXCLUSIVE;
-	}
-	vn_lock(vp, lock_flags | LK_RETRY);
+	vn_lock(vp, vn_lktype_write(mp, vp) | LK_RETRY);
 	AUDIT_ARG_VNODE1(vp);
 	if (vp->v_object != NULL) {
 		VM_OBJECT_WLOCK(vp->v_object);
diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -653,11 +653,7 @@
 			    (error = vn_start_write(vp, &mp, V_WAIT | PCATCH))
 			    != 0)
 				goto out;
-			if (MNT_SHARED_WRITES(mp) ||
-			    ((mp == NULL) && MNT_SHARED_WRITES(vp->v_mount)))
-				lock_flags = LK_SHARED;
-			else
-				lock_flags = LK_EXCLUSIVE;
+			lock_flags = vn_lktype_write(mp, vp);
 		} else
 			lock_flags = LK_SHARED;
 		vn_lock(vp, lock_flags | LK_RETRY);
@@ -1106,7 +1102,7 @@
 	struct vnode *vp;
 	struct mount *mp;
 	off_t orig_offset;
-	int error, ioflag, lock_flags;
+	int error, ioflag;
 	int advice;
 	bool need_finished_write;
 
@@ -1147,14 +1143,7 @@
 
 	advice = get_advice(fp, uio);
 
-	if (MNT_SHARED_WRITES(mp) ||
-	    (mp == NULL && MNT_SHARED_WRITES(vp->v_mount))) {
-		lock_flags = LK_SHARED;
-	} else {
-		lock_flags = LK_EXCLUSIVE;
-	}
-
-	vn_lock(vp, lock_flags | LK_RETRY);
+	vn_lock(vp, vn_lktype_write(mp, vp) | LK_RETRY);
 	switch (advice) {
 	case POSIX_FADV_NORMAL:
 	case POSIX_FADV_SEQUENTIAL:
@@ -3060,7 +3049,7 @@
 {
 	struct mount *mp;
 	off_t dataoff, holeoff, xfer2;
-	int error, lckf;
+	int error;
 
 	/*
 	 * Loop around doing writes of blksize until write has been completed.
@@ -3099,11 +3088,7 @@
 				VOP_UNLOCK(outvp);
 			}
 		} else {
-			if (MNT_SHARED_WRITES(mp))
-				lckf = LK_SHARED;
-			else
-				lckf = LK_EXCLUSIVE;
-			error = vn_lock(outvp, lckf);
+			error = vn_lock(outvp, vn_lktype_write(mp, outvp));
 			if (error == 0) {
 				error = vn_rdwr(UIO_WRITE, outvp, dat, xfer2,
 				    outoff, UIO_SYSSPACE, IO_NODELOCKED,
@@ -3532,3 +3517,12 @@
 	if (vp2 != NULL)
 		ASSERT_VOP_ELOCKED(vp2, "vp2 ret");
 }
+
+int
+vn_lktype_write(struct mount *mp, struct vnode *vp)
+{
+	if (MNT_SHARED_WRITES(mp) ||
+	    (mp == NULL && MNT_SHARED_WRITES(vp->v_mount)))
+		return (LK_SHARED);
+	return (LK_EXCLUSIVE);
+}
diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h
--- a/sys/sys/vnode.h
+++ b/sys/sys/vnode.h
@@ -1089,6 +1089,7 @@
 void vn_fsid(struct vnode *vp, struct vattr *va);
 
 int vn_dir_check_exec(struct vnode *vp, struct componentname *cnp);
+int vn_lktype_write(struct mount *mp, struct vnode *vp);
 
 #define VOP_UNLOCK_FLAGS(vp, flags)	({				\
 	struct vnode *_vp = (vp);					\
diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c
--- a/sys/vm/vm_pageout.c
+++ b/sys/vm/vm_pageout.c
@@ -606,7 +606,7 @@
 	struct mount *mp;
 	vm_object_t object;
 	vm_pindex_t pindex;
-	int error, lockmode;
+	int error;
 
 	object = m->object;
 	VM_OBJECT_ASSERT_WLOCKED(object);
@@ -640,9 +640,7 @@
 		vm_object_reference_locked(object);
 		pindex = m->pindex;
 		VM_OBJECT_WUNLOCK(object);
-		lockmode = MNT_SHARED_WRITES(vp->v_mount) ?
-		    LK_SHARED : LK_EXCLUSIVE;
-		if (vget(vp, lockmode | LK_TIMELOCK)) {
+		if (vget(vp, vn_lktype_write(NULL, vp) | LK_TIMELOCK) != 0) {
 			vp = NULL;
 			error = EDEADLK;
 			goto unlock_mp;