Index: sys/vm/swap_pager.c
===================================================================
--- sys/vm/swap_pager.c
+++ sys/vm/swap_pager.c
@@ -321,8 +321,6 @@
 #endif
 }
 
-#define SWM_POP		0x01	/* pop out			*/
-
 static int swap_pager_full = 2;	/* swap space exhaustion (task killing) */
 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/
 static struct mtx swbuf_mtx;	/* to sync nsw_wcount_async */
@@ -423,7 +421,8 @@
 static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t);
 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t);
 static void swp_pager_meta_free_all(vm_object_t);
-static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int);
+static daddr_t swp_pager_meta_lookup(vm_object_t, vm_pindex_t);
+static daddr_t swp_pager_meta_remove(vm_object_t, vm_pindex_t);
 
 static void
 swp_pager_init_freerange(daddr_t *start, daddr_t *num)
@@ -956,8 +955,10 @@
 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject,
     vm_pindex_t offset, int destroysource)
 {
+	struct swblk *sb;
 	vm_pindex_t i;
 	daddr_t dstaddr, n_free, s_free, srcaddr;
+	int limit, start;
 
 	VM_OBJECT_ASSERT_WLOCKED(srcobject);
 	VM_OBJECT_ASSERT_WLOCKED(dstobject);
@@ -985,11 +986,39 @@
 	 * Transfer source to destination.
 	 */
 	swp_pager_init_freerange(&s_free, &n_free);
-	for (i = 0; i < dstobject->size; ++i) {
-		srcaddr = swp_pager_meta_ctl(srcobject, i + offset, SWM_POP);
-		if (srcaddr == SWAPBLK_NONE)
+	for (i = 0; i < dstobject->size; i++) {
+		/*
+		 * Find the next source block and remove it.
+		 */
+		sb = SWAP_PCTRIE_LOOKUP_GE(&srcobject->un_pager.swp.swp_blks,
+		    rounddown(i + offset, SWAP_META_PAGES));
+		if (sb == NULL || sb->p >= dstobject->size + offset)
+			break;
+		limit = dstobject->size + offset - sb->p < SWAP_META_PAGES ?
+		    dstobject->size + offset - sb->p : SWAP_META_PAGES;
+		for (start = i + offset > sb->p ? i + offset - sb->p : 0;
+		     start < limit; start++) {
+			if (sb->d[start] != SWAPBLK_NONE) {
+				i = sb->p + start - offset;
+				break;
+			}
+		}
+		if (start == limit) {
+			i = sb->p + start - offset - 1;
 			continue;
-		dstaddr = swp_pager_meta_ctl(dstobject, i, 0);
+		}
+		srcaddr = sb->d[start];
+		sb->d[start] = SWAPBLK_NONE;
+		if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) {
+			SWAP_PCTRIE_REMOVE(&srcobject->un_pager.swp.swp_blks,
+			    rounddown(i + offset, SWAP_META_PAGES));
+			uma_zfree(swblk_zone, sb);
+		}
+
+		/*
+		 * Find the matching destination block, if any.
+		 */
+		dstaddr = swp_pager_meta_lookup(dstobject, i);
 		if (dstaddr != SWAPBLK_NONE) {
 			/*
 			 * Destination has valid swapblk or it is represented
@@ -1057,7 +1086,7 @@
 	/*
 	 * do we have good backing store at the requested index ?
 	 */
-	blk0 = swp_pager_meta_ctl(object, pindex, 0);
+	blk0 = swp_pager_meta_lookup(object, pindex);
 	if (blk0 == SWAPBLK_NONE) {
 		if (before)
 			*before = 0;
@@ -1073,7 +1102,7 @@
 		for (i = 1; i < SWB_NPAGES; i++) {
 			if (i > pindex)
 				break;
-			blk = swp_pager_meta_ctl(object, pindex - i, 0);
+			blk = swp_pager_meta_lookup(object, pindex - i);
 			if (blk != blk0 - i)
 				break;
 		}
@@ -1085,7 +1114,7 @@
 	 */
 	if (after != NULL) {
 		for (i = 1; i < SWB_NPAGES; i++) {
-			blk = swp_pager_meta_ctl(object, pindex + i, 0);
+			blk = swp_pager_meta_lookup(object, pindex + i);
 			if (blk != blk0 + i)
 				break;
 		}
@@ -1118,7 +1147,7 @@
 {
 	daddr_t srcaddr;
 
-	srcaddr = swp_pager_meta_ctl(m->object, m->pindex, SWM_POP);
+	srcaddr = swp_pager_meta_remove(m->object, m->pindex);
 	if (srcaddr != SWAPBLK_NONE)
 		swp_pager_freeswapspace(srcaddr, 1);
 }
@@ -1214,7 +1243,7 @@
 	vm_object_pip_add(object, count);
 
 	pindex = bm->pindex;
-	blk = swp_pager_meta_ctl(object, pindex, 0);
+	blk = swp_pager_meta_lookup(object, pindex);
 	KASSERT(blk != SWAPBLK_NONE,
 	    ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex));
 
@@ -2085,28 +2114,55 @@
 }
 
 /*
- * SWP_PAGER_METACTL() -  misc control of swap meta data.
+ * SWP_PAGER_META_LOOKUP() -  look up swap meta data.
  *
- *	This routine is capable of looking up, or removing swapblk
- *	assignments in the swap meta data.  It returns the swapblk being
- *	looked-up, popped, or SWAPBLK_NONE if the block was invalid.
+ *	Look up swapblk assignments in the swap meta data.  Returns the swapblk
+ *	for (pindex = 0; (sb = being looked-up, or SWAPBLK_NONE if the block
+ *	was invalid.
  *
  *	When acting on a busy resident page and paging is in progress, we
  *	have to wait until paging is complete but otherwise can act on the
  *	busy page.
+ */
+static daddr_t
+swp_pager_meta_lookup(vm_object_t object, vm_pindex_t pindex)
+{
+	struct swblk *sb;
+
+	VM_OBJECT_ASSERT_LOCKED(object);
+
+	/*
+	 * The meta data only exists if the object is OBJT_SWAP
+	 * and even then might not be allocated yet.
+	 */
+	if (object->type != OBJT_SWAP)
+		return (SWAPBLK_NONE);
+
+	sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks,
+	    rounddown(pindex, SWAP_META_PAGES));
+	if (sb == NULL)
+		return (SWAPBLK_NONE);
+	return (sb->d[pindex % SWAP_META_PAGES]);
+}
+
+/*
+ * SWP_PAGER_META_REMOVE() -  remove swap meta data.
  *
- *	SWM_POP		remove from meta data but do not free it
+ *	This routine is capable of removing swapblk assignments in the swap
+ *	for (pindex = 0; (sb = meta data.  It returns the swapblk being
+ *	removed, or SWAPBLK_NONE if the block was invalid.
+ *
+ *	When acting on a busy resident page and paging is in progress, we
+ *	have to wait until paging is complete but otherwise can act on the
+ *	busy page.
  */
 static daddr_t
-swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags)
+swp_pager_meta_remove(vm_object_t object, vm_pindex_t pindex)
 {
 	struct swblk *sb;
 	daddr_t r1;
 
-	if ((flags & SWM_POP) != 0)
-		VM_OBJECT_ASSERT_WLOCKED(object);
-	else
-		VM_OBJECT_ASSERT_LOCKED(object);
+	VM_OBJECT_ASSERT_WLOCKED(object);
 
 	/*
 	 * The meta data only exists if the object is OBJT_SWAP
@@ -2122,13 +2178,11 @@
 	r1 = sb->d[pindex % SWAP_META_PAGES];
 	if (r1 == SWAPBLK_NONE)
 		return (SWAPBLK_NONE);
-	if ((flags & SWM_POP) != 0) {
-		sb->d[pindex % SWAP_META_PAGES] = SWAPBLK_NONE;
-		if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) {
-			SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks,
-			    rounddown(pindex, SWAP_META_PAGES));
-			uma_zfree(swblk_zone, sb);
-		}
+	sb->d[pindex % SWAP_META_PAGES] = SWAPBLK_NONE;
+	if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) {
+		SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks,
+		    rounddown(pindex, SWAP_META_PAGES));
+		uma_zfree(swblk_zone, sb);
 	}
 	return (r1);
 }