Index: sys/kern/vfs_subr.c
===================================================================
--- sys/kern/vfs_subr.c
+++ sys/kern/vfs_subr.c
@@ -1264,23 +1264,6 @@
 	vlowat = vhiwat / 2;
 }
 
-/* XXX some names and initialization are bad for limits and watermarks. */
-static int
-vspace(void)
-{
-	u_long rnumvnodes, rfreevnodes;
-	int space;
-
-	rnumvnodes = atomic_load_long(&numvnodes);
-	rfreevnodes = atomic_load_long(&freevnodes);
-	if (rnumvnodes > desiredvnodes)
-		return (0);
-	space = desiredvnodes - rnumvnodes;
-	if (freevnodes > wantfreevnodes)
-		space += rfreevnodes - wantfreevnodes;
-	return (space);
-}
-
 static void
 vnlru_return_batch_locked(struct mount *mp)
 {
@@ -1346,13 +1329,41 @@
 static struct proc *vnlruproc;
 static int vnlruproc_sig;
 
+static bool
+vnlru_under(u_long rnumvnodes, u_long limit)
+{
+	u_long rfreevnodes, space;
+
+	if (__predict_false(rnumvnodes > desiredvnodes))
+		return (true);
+
+	space = desiredvnodes - rnumvnodes;
+	if (space < limit) {
+		rfreevnodes = atomic_load_long(&freevnodes);
+		if (rfreevnodes > wantfreevnodes)
+			space += rfreevnodes - wantfreevnodes;
+	}
+	return (space < limit);
+}
+
+static void
+vnlru_kick(void)
+{
+
+	mtx_assert(&vnode_free_list_mtx, MA_OWNED);
+	if (vnlruproc_sig == 0) {
+		vnlruproc_sig = 1;
+		wakeup(vnlruproc);
+	}
+}
+
 static void
 vnlru_proc(void)
 {
 	u_long rnumvnodes, rfreevnodes;
 	struct mount *mp, *nmp;
 	unsigned long onumvnodes;
-	int done, force, trigger, usevnodes, vsp;
+	int done, force, trigger, usevnodes;
 	bool reclaim_nc_src;
 
 	EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, vnlruproc,
@@ -1368,8 +1379,10 @@
 		 * adjusted using its sysctl, or emergency growth), first
 		 * try to reduce it by discarding from the free list.
 		 */
-		if (rnumvnodes > desiredvnodes)
+		if (rnumvnodes > desiredvnodes) {
 			vnlru_free_locked(rnumvnodes - desiredvnodes, NULL);
+			rnumvnodes = atomic_load_long(&numvnodes);
+		}
 		/*
 		 * Sleep if the vnode cache is in a good state.  This is
 		 * when it is not over-full and has space for about a 4%
@@ -1381,8 +1394,7 @@
 			force = 1;
 			vstir = 0;
 		}
-		vsp = vspace();
-		if (vsp >= vlowat && force == 0) {
+		if (force == 0 && !vnlru_under(rnumvnodes, vlowat)) {
 			vnlruproc_sig = 0;
 			wakeup(&vnlruproc_sig);
 			msleep(vnlruproc, &vnode_free_list_mtx,
@@ -1452,8 +1464,7 @@
 		 * After becoming active to expand above low water, keep
 		 * active until above high water.
 		 */
-		vsp = vspace();
-		force = vsp < vhiwat;
+		force = vnlru_under(numvnodes, vhiwat) ? 1 : 0;
 	}
 }
 
@@ -1529,18 +1540,6 @@
 	return (0);
 }
 
-static void
-vcheckspace(void)
-{
-	int vsp;
-
-	vsp = vspace();
-	if (vsp < vlowat && vnlruproc_sig == 0) {
-		vnlruproc_sig = 1;
-		wakeup(vnlruproc);
-	}
-}
-
 /*
  * Wait if necessary for space for a new vnode.
  */
@@ -1574,11 +1573,19 @@
 static struct vnode *
 vn_alloc(struct mount *mp)
 {
+	u_long rnumvnodes;
 	static int cyclecount;
 	int error __unused;
 
+	rnumvnodes = atomic_fetchadd_long(&numvnodes, 1) + 1;
+	if (__predict_true(!vnlru_under(rnumvnodes, vlowat)))
+		goto alloc;
+
+	atomic_subtract_long(&numvnodes, 1);
+
 	mtx_lock(&vnode_free_list_mtx);
-	if (numvnodes < desiredvnodes)
+	rnumvnodes = atomic_load_long(&numvnodes);
+	if (rnumvnodes < desiredvnodes)
 		cyclecount = 0;
 	else if (cyclecount++ >= freevnodes) {
 		cyclecount = 0;
@@ -1594,7 +1601,7 @@
 	 * should be chosen so that we never wait or even reclaim from
 	 * the free list to below its target minimum.
 	 */
-	if (numvnodes + 1 <= desiredvnodes)
+	if (rnumvnodes + 1 <= desiredvnodes)
 		;
 	else if (freevnodes > 0)
 		vnlru_free_locked(1, NULL);
@@ -1608,9 +1615,11 @@
 		}
 #endif
 	}
-	vcheckspace();
-	atomic_add_long(&numvnodes, 1);
+	rnumvnodes = atomic_fetchadd_long(&numvnodes, 1) + 1;
+	if (vnlru_under(rnumvnodes, vlowat))
+		vnlru_kick();
 	mtx_unlock(&vnode_free_list_mtx);
+alloc:
 	return (uma_zalloc(vnode_zone, M_WAITOK));
 }