From 0e5b52868f31dabc555eb35038e1b6b20a974da5 Mon Sep 17 00:00:00 2001
From: David Greenman <dg@FreeBSD.org>
Date: Thu, 18 May 1995 05:09:54 +0000
Subject: Fixed a bug that managed to slip in during Poul's dynamic swap
 partition changes. The check for nswap was bogus, but the code was so
 convoluted that it was difficult to tell. It's better now. :-)

Reviewed by:	David Greenman (extensively), and John Dyson
Submitted by:	Poul-Henning Kamp, w/tweaks by me.
---
 sys/vm/vm_swap.c | 28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/sys/vm/vm_swap.c b/sys/vm/vm_swap.c
index 682d11a953a9..d66fb018c1e5 100644
--- a/sys/vm/vm_swap.c
+++ b/sys/vm/vm_swap.c
@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)vm_swap.c	8.5 (Berkeley) 2/17/94
- * $Id: vm_swap.c,v 1.16 1995/05/12 03:54:59 phk Exp $
+ * $Id: vm_swap.c,v 1.17 1995/05/14 03:00:10 davidg Exp $
  */
 
 #include <sys/param.h>
@@ -58,7 +58,7 @@
 #endif
 static struct swdevt should_be_malloced[NSWAPDEV];
 struct swdevt *swdevt = should_be_malloced;
-int nswap;
+int nswap;			/* first block after the interleaved devs */
 int nswdev = NSWAPDEV;
 int vm_swap_size;
 int bswneeded;
@@ -73,12 +73,6 @@ swstrategy(bp)
 	struct vnode *vp;
 
 	sz = howmany(bp->b_bcount, DEV_BSIZE);
-	if (bp->b_blkno + sz > nswap) {
-		bp->b_error = EINVAL;
-		bp->b_flags |= B_ERROR;
-		biodone(bp);
-		return;
-	}
 	if (nswdev > 1) {
 		off = bp->b_blkno % dmmax;
 		if (off + sz > dmmax) {
@@ -94,6 +88,12 @@ swstrategy(bp)
 	} else
 		index = 0;
 	sp = &swdevt[index];
+	if (bp->b_blkno + sz > sp->sw_nblks) {
+		bp->b_error = EINVAL;
+		bp->b_flags |= B_ERROR;
+		biodone(bp);
+		return;
+	}
 	if ((bp->b_dev = sp->sw_dev) == NODEV)
 		panic("swstrategy");
 	if (sp->sw_vp == NULL) {
@@ -241,17 +241,11 @@ swaponvp(p, vp, dev, nblks)
 	sp->sw_nblks = nblks;
 
 	if (nblks * nswdev > nswap)
-		nswap = nblks * nswdev;
+		nswap = (nblks+1) * nswdev;
 
 	for (dvbase = dmmax; dvbase < nblks; dvbase += dmmax) {
-		blk = nblks - dvbase;
-
-		if ((vsbase = index * dmmax + dvbase * nswdev) >= nswap)
-			panic("swfree");
-		if (blk > dmmax)
-			blk = dmmax;
-		/* XXX -- we need to exclude the first cluster as above */
-		/* but for now, this will work fine... */
+		blk = min(nblks - dvbase,dmmax);
+		vsbase = index * dmmax + dvbase * nswdev;
 		rlist_free(&swaplist, vsbase, vsbase + blk - 1);
 		vm_swap_size += blk;
 	}
-- 
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