Increase size of the clone bitmap. A limit of only 64 device clones

turned out to be too low for the upcoming work on cloning bpf. The new
limit is 1024 device clones. As part of the size increase, the bitmap
has been changed to be allocated separately to avoid bloating all device
nodes, as suggested by guenther, millert and deraadt.

ok millert mikeb

3 files changed, 20 insertions, 7 deletions

diff --git a/sys/kern/spec_vnops.c b/sys/kern/spec_vnops.c
index 265a558d4b5..9a5e9e0f2b0 100644
--- a/sys/kern/spec_vnops.c
+++ b/sys/kern/spec_vnops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: spec_vnops.c,v 1.86 2016/03/19 12:04:15 natano Exp $	*/
+/*	$OpenBSD: spec_vnops.c,v 1.87 2016/03/31 20:00:17 natano Exp $	*/
 /*	$NetBSD: spec_vnops.c,v 1.29 1996/04/22 01:42:38 christos Exp $	*/
 
 /*
@@ -707,13 +707,14 @@ spec_open_clone(struct vop_open_args *ap)
 	if (minor(vp->v_rdev) >= (1 << CLONE_SHIFT))
 		return (ENXIO);
 
-	for (i = 1; i < sizeof(vp->v_specbitmap) * NBBY; i++)
+	for (i = 1; i < CLONE_MAP_SZ * NBBY; i++) {
 		if (isclr(vp->v_specbitmap, i)) {
 			setbit(vp->v_specbitmap, i);
 			break;
 		}
+	}
 
-	if (i == sizeof(vp->v_specbitmap) * NBBY)
+	if (i == CLONE_MAP_SZ * NBBY)
 		return (EBUSY); /* too many open instances */
 
 	error = cdevvp(makedev(major(vp->v_rdev),
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 966e8977f9c..fb4e22da8d9 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_subr.c,v 1.240 2016/03/19 12:04:15 natano Exp $	*/
+/*	$OpenBSD: vfs_subr.c,v 1.241 2016/03/31 20:00:17 natano Exp $	*/
 /*	$NetBSD: vfs_subr.c,v 1.53 1996/04/22 01:39:13 christos Exp $	*/
 
 /*
@@ -555,7 +555,13 @@ loop:
 		nvp->v_specnext = *vpp;
 		nvp->v_specmountpoint = NULL;
 		nvp->v_speclockf = NULL;
-		memset(nvp->v_specbitmap, 0, sizeof(nvp->v_specbitmap));
+		nvp->v_specbitmap = NULL;
+		if (nvp_rdev == VCHR &&
+		    (cdevsw[major(nvp_rdev)].d_flags & D_CLONE) &&
+		    minor(nvp_rdev) >> CLONE_SHIFT == 0) {
+			nvp->v_specbitmap = malloc(CLONE_MAP_SZ, M_VNODE,
+			    M_WAITOK | M_ZERO);
+		}
 		*vpp = nvp;
 		if (vp != NULLVP) {
 			nvp->v_flag |= VALIASED;
@@ -1093,6 +1099,11 @@ vgonel(struct vnode *vp, struct proc *p)
 				vx->v_flag &= ~VALIASED;
 			vp->v_flag &= ~VALIASED;
 		}
+		if (vp->v_rdev == VCHR &&
+		    (cdevsw[major(vp->v_rdev)].d_flags & D_CLONE) &&
+		    minor(vp->v_rdev) >> CLONE_SHIFT == 0) {
+			free(vp->v_specbitmap, M_VNODE, CLONE_MAP_SZ);
+		}
 		free(vp->v_specinfo, M_VNODE, sizeof(struct specinfo));
 		vp->v_specinfo = NULL;
 	}
diff --git a/sys/sys/specdev.h b/sys/sys/specdev.h
index 092b903808f..b550c720497 100644
--- a/sys/sys/specdev.h
+++ b/sys/sys/specdev.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: specdev.h,v 1.34 2013/11/02 00:16:31 deraadt Exp $	*/
+/*	$OpenBSD: specdev.h,v 1.35 2016/03/31 20:00:17 natano Exp $	*/
 /*	$NetBSD: specdev.h,v 1.12 1996/02/13 13:13:01 mycroft Exp $	*/
 
 /*
@@ -46,7 +46,7 @@ struct specinfo {
 	daddr_t si_lastr;
 	union {
 		struct vnode *ci_parent; /* pointer back to parent device */
-		u_int8_t ci_bitmap[8]; /* bitmap of devices cloned off us */
+		u_int8_t *ci_bitmap; /* bitmap of devices cloned off us */
 	} si_ci;
 };
 
@@ -71,6 +71,7 @@ struct cloneinfo {
  * This gives us 8 bits for encoding the real minor number.
  */
 #define CLONE_SHIFT	8
+#define CLONE_MAP_SZ	128
 
 /*
  * Special device management