From 2589f2499de03fe756d249d14d9024dc9faca817 Mon Sep 17 00:00:00 2001
From: Mark Murray <markm@FreeBSD.org>
Date: Sun, 25 Jun 2000 09:44:32 +0000
Subject: [PATCH] Nifty idea from Jeroen van Gelderen; don't call a routine to
 check if we are using the /dev/zero device, just check a flag (supplied by
 /dev/zero). Reviewed by:	dfr

---
 sys/vm/vm_mmap.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sys/vm/vm_mmap.c b/sys/vm/vm_mmap.c
index 922234ad15e..b196d6f81a6 100644
--- a/sys/vm/vm_mmap.c
+++ b/sys/vm/vm_mmap.c
@@ -299,7 +299,8 @@ mmap(p, uap)
 		 * XXX hack to handle use of /dev/zero to map anon memory (ala
 		 * SunOS).
 		 */
-		if (vp->v_type == VCHR && iszerodev(vp->v_rdev)) {
+		if ((vp->v_type == VCHR) && 
+		    (vp->v_rdev->si_devsw->d_flags & D_MMAP_ANON)) {
 			handle = NULL;
 			maxprot = VM_PROT_ALL;
 			flags |= MAP_ANON;