--- old/usr/src/uts/common/fs/zfs/space_map.c	Mon Apr  7 00:45:25 2008
+++ new/usr/src/uts/common/fs/zfs/space_map.c	Mon Apr  7 00:45:25 2008
@@ -180,7 +180,29 @@
 	sm->sm_space -= size;
 }
 
+
+
 int
+space_map_fold(space_map_t *sm, uint8_t oldwidth, uint8_t newwidth)
+{
+	space_seg_t *ss;
+	uint64_t d, r;
+
+	ASSERT(MUTEX_HELD(sm->sm_lock));
+
+	for (ss = avl_first(&sm->sm_root); ss != NULL;
+	    ss = AVL_NEXT(&sm->sm_root, ss)) {
+		d = ss->ss_start / oldwidth;
+		r = ss->ss_start % oldwidth;
+		ss->ss_start = d * newwidth + r;
+
+		d = ss->ss_end / oldwidth;
+		r = ss->ss_end % oldwidth;
+		ss->ss_end = d * newwidth + r;
+	}
+}
+
+int
 space_map_contains(space_map_t *sm, uint64_t start, uint64_t size)
 {
 	avl_index_t where;
@@ -345,9 +367,18 @@
 		for (entry = entry_map; entry < entry_map_end; entry++) {
 			uint64_t e = *entry;
 
-			if (SM_DEBUG_DECODE(e))		/* Skip debug entries */
+			if (SM_IS_DEBUG(e))		/* Skip debug entries */
 				continue;
 
+			if (SM_IS_SPECIAL(e)) {
+				uint8_t oldwidth, newwidth;
+				ASSERT(SM_SPECIAL_ACTION_DECODE(e) == SM_FOLD);
+				oldwidth = BF64_ENCODE(e, 0, 8);
+				newwidth = BF64_ENCODE(e, 8, 8);
+				space_map_fold(sm, oldwidth, newwidth);
+				continue;
+			}
+
 			(SM_TYPE_DECODE(e) == maptype ?
 			    space_map_add : space_map_remove)(sm,
 			    (SM_OFFSET_DECODE(e) << sm->sm_shift) + mapstart,