diff -urNp ref/drivers/md/lvm-snap.c 2.4.20pre5aa1/drivers/md/lvm-snap.c
--- ref/drivers/md/lvm-snap.c	Thu Aug 29 02:13:10 2002
+++ 2.4.20pre5aa1/drivers/md/lvm-snap.c	Fri Aug 30 02:22:36 2002
@@ -113,6 +113,8 @@ lvm_find_exception_table(kdev_t org_dev,
 	lv_block_exception_t * ret;
 	int i = 0;
 
+	if (!hash_table)
+		BUG() ;
 	hash_table = &hash_table[hashfn(org_dev, org_start, mask, chunk_size)];
 	ret = NULL;
 	for (next = hash_table->next; next != hash_table; next = next->next)
diff -urNp ref/drivers/md/lvm.c 2.4.20pre5aa1/drivers/md/lvm.c
--- ref/drivers/md/lvm.c	Thu Aug 29 02:13:10 2002
+++ 2.4.20pre5aa1/drivers/md/lvm.c	Fri Aug 30 02:24:20 2002
@@ -1151,7 +1151,8 @@ static void __remap_snapshot(kdev_t rdev
 
 	/* we must redo lvm_snapshot_remap_block in order to avoid a
 	   race condition in the gap where no lock was held */
-	if (!lvm_snapshot_remap_block(&rdev, &rsector, pe_start, lv) &&
+	if (lv->lv_block_exception && 
+	    !lvm_snapshot_remap_block(&rdev, &rsector, pe_start, lv) &&
 	    !lvm_snapshot_COW(rdev, rsector, pe_start, rsector, vg, lv))
 		lvm_write_COW_table_block(vg, lv);
 
@@ -1160,11 +1161,12 @@ static void __remap_snapshot(kdev_t rdev
 
 static inline void _remap_snapshot(kdev_t rdev, ulong rsector,
 				   ulong pe_start, lv_t *lv, vg_t *vg) {
-	int r;
+	int r = 0;
 
 	/* check to see if this chunk is already in the snapshot */
 	down_read(&lv->lv_lock);
-	r = lvm_snapshot_remap_block(&rdev, &rsector, pe_start, lv);
+	if (lv->lv_block_exception)
+		r = lvm_snapshot_remap_block(&rdev, &rsector, pe_start, lv);
 	up_read(&lv->lv_lock);
 
 	if (!r)