diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c
index 5771a9c60dd3..0fb5d2203113 100644
--- a/sys/vm/swap_pager.c
+++ b/sys/vm/swap_pager.c
@@ -104,12 +104,6 @@
 #define SWM_FREE	0x02	/* free, period			*/
 #define SWM_POP		0x04	/* pop out			*/
 
-/*
- * vm_swap_size is in page-sized chunks now.  It was DEV_BSIZE'd chunks
- * in the old system.
- */
-extern int vm_swap_size;	/* number of free swap blocks, in pages */
-
 int swap_pager_full;		/* swap space exhaustion (task killing) */
 static int swap_pager_almost_full; /* swap space exhaustion (w/ hysteresis)*/
 static int nsw_rcount;		/* free read buffers			*/
@@ -124,10 +118,6 @@ static int swhash_mask;
 static int swap_async_max = 4;	/* maximum in-progress async I/O's	*/
 static struct sx sw_alloc_sx;
 
-/* from vm_swap.c */
-extern struct vnode *swapdev_vp;
-extern struct swdevt *swdevt;
-extern int nswdev;
 
 SYSCTL_INT(_vm, OID_AUTO, swap_async_max,
         CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops");
@@ -185,8 +175,7 @@ static void waitchainbuf(struct bio *bp, int count, int done);
  * swap_*() routines are externally accessible.  swp_*() routines are
  * internal.
  */
-int dmmax;
-static int dmmax_mask;
+int dmmax, dmmax_mask;
 int nswap_lowat = 128;		/* in pages, swap_pager_almost_full warn */
 int nswap_hiwat = 512;		/* in pages, swap_pager_almost_full warn */
 
diff --git a/sys/vm/swap_pager.h b/sys/vm/swap_pager.h
index 48ddf0011f29..23fc08508846 100644
--- a/sys/vm/swap_pager.h
+++ b/sys/vm/swap_pager.h
@@ -84,6 +84,15 @@ extern int swap_pager_full;
 extern struct blist *swapblist;
 extern struct uma_zone *swap_zone;
 extern int nswap_lowat, nswap_hiwat;
+extern int dmmax, dmmax_mask;
+extern struct vnode *swapdev_vp;
+extern struct swdevt *swdevt;
+extern int nswdev;
+/*
+ * vm_swap_size is in page-sized chunks now.  It was DEV_BSIZE'd chunks
+ * in the old system.
+ */
+extern int vm_swap_size;	/* number of free swap blocks, in pages */
 
 void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *);
 boolean_t swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after);
diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c
index cff7cf6afc69..b94854e1ac6d 100644
--- a/sys/vm/vm_pageout.c
+++ b/sys/vm/vm_pageout.c
@@ -144,7 +144,6 @@ int vm_pageout_pages_needed=0;	/* flag saying that the pageout daemon needs page
 static int vm_pageout_req_swapout;	/* XXX */
 static int vm_daemon_needed;
 #endif
-extern int vm_swap_size;
 static int vm_max_launder = 32;
 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0;
 static int vm_pageout_full_stats_interval = 0;
diff --git a/sys/vm/vm_swap.c b/sys/vm/vm_swap.c
index 3f75289053a5..14530af9b47e 100644
--- a/sys/vm/vm_swap.c
+++ b/sys/vm/vm_swap.c
@@ -67,7 +67,6 @@
  */
 
 typedef	int32_t	swblk_t;	/* swap offset */
-extern int dmmax;
 
 #ifndef NSWAPDEV
 #define NSWAPDEV	4
@@ -351,7 +350,7 @@ swaponvp(td, vp, dev, nblks)
 	 * DEV_BSIZE'd.   aligned_nblks is used to calculate the
 	 * size of the swap bitmap, taking into account the stripe size.
 	 */
-	aligned_nblks = (nblks + (dmmax - 1)) & ~(u_long)(dmmax - 1);
+	aligned_nblks = (nblks + dmmax_mask) & ~(u_long)dmmax_mask;
 
 	if (aligned_nblks * nswdev > nswap)
 		nswap = aligned_nblks * nswdev;
@@ -470,7 +469,7 @@ found:
 		nblks = max(nblks, sp->sw_nblks);
 	}
 
-	aligned_nblks = (nblks + (dmmax - 1)) & ~(u_long)(dmmax - 1);
+	aligned_nblks = (nblks + dmmax_mask) & ~(u_long)dmmax_mask;
 	nswap = aligned_nblks * nswdev;
 
 	if (nswap == 0) {