amap_pp_adjref could fragment ppref array; fix by merging adjacent chunks;

from Chuck Silvers; okay art@

1 files changed, 16 insertions, 12 deletions

diff --git a/sys/uvm/uvm_amap.c b/sys/uvm/uvm_amap.c
index 0b38ac13faf..de6bea7db3e 100644
--- a/sys/uvm/uvm_amap.c
+++ b/sys/uvm/uvm_amap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_amap.c,v 1.22 2002/02/12 18:36:53 provos Exp $	*/
+/*	$OpenBSD: uvm_amap.c,v 1.23 2002/02/19 17:57:34 provos Exp $	*/
 /*	$NetBSD: uvm_amap.c,v 1.27 2000/11/25 06:27:59 chs Exp $	*/
 
 /*
@@ -933,19 +933,16 @@ amap_pp_adjref(amap, curslot, slotlen, adjval)
 	vsize_t slotlen;
 	int adjval;
 {
-	int stopslot, *ppref, lcv;
-	int ref, len;
-
-	/*
-	 * get init values
-	 */
+ 	int stopslot, *ppref, lcv, prevlcv;
+ 	int ref, len, prevref, prevlen;
 
 	stopslot = curslot + slotlen;
 	ppref = amap->am_ppref;
+ 	prevlcv = -1;
 
 	/*
-	 * first advance to the correct place in the ppref array, fragment
-	 * if needed.
+ 	 * first advance to the correct place in the ppref array,
+ 	 * fragment if needed.
 	 */
 
 	for (lcv = 0 ; lcv < curslot ; lcv += len) {
@@ -955,10 +952,13 @@ amap_pp_adjref(amap, curslot, slotlen, adjval)
 			pp_setreflen(ppref, curslot, ref, len - (curslot -lcv));
 			len = curslot - lcv;   /* new length of entry @ lcv */
 		}
+		prevlcv = lcv;
 	}
+	pp_getreflen(ppref, prevlcv, &prevref, &prevlen);
 
 	/*
-	 * now adjust reference counts in range (make sure we dont overshoot)
+	 * now adjust reference counts in range.  merge the first
+	 * changed entry with the last unchanged entry if possible.
 	 */
 
 	if (lcv != curslot)
@@ -972,10 +972,14 @@ amap_pp_adjref(amap, curslot, slotlen, adjval)
 			    len - (stopslot - lcv));
 			len = stopslot - lcv;
 		}
-		ref = ref + adjval;    /* ADJUST! */
+		ref += adjval;
 		if (ref < 0)
 			panic("amap_pp_adjref: negative reference count");
-		pp_setreflen(ppref, lcv, ref, len);
+		if (lcv == prevlcv + prevlen && ref == prevref) {
+			pp_setreflen(ppref, prevlcv, ref, prevlen + len);
+		} else {
+			pp_setreflen(ppref, lcv, ref, len);
+		}
 		if (ref == 0)
 			amap_wiperange(amap, lcv, len);
 	}