Count exceptions in progress.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
 drivers/md/dm-snap.c |    9 +++++++++
 1 file changed, 9 insertions(+)

Index: linux-2.6.31-fast-new-2/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.31-fast-new-2.orig/drivers/md/dm-snap.c	2009-10-16 21:52:43.000000000 +0200
+++ linux-2.6.31-fast-new-2/drivers/md/dm-snap.c	2009-10-16 21:52:48.000000000 +0200
@@ -97,8 +97,12 @@ struct dm_snapshot {
 
 	mempool_t *pending_pool;
 
+	/* The number of pending exceptions allocated from the mempool */
 	atomic_t pending_exceptions_count;
 
+	/* The number of entries in "pending" table */
+	int pending_exceptions_submitted;
+
 	struct dm_exception_table pending;
 	struct dm_exception_table complete;
 
@@ -932,6 +936,7 @@ static int snapshot_ctr(struct dm_target
 	s->active = 0;
 	s->suspended = 0;
 	atomic_set(&s->pending_exceptions_count, 0);
+	s->pending_exceptions_submitted = 0;
 	s->handover = 0;
 	s->handover_snap = NULL;
 	s->merge_running = 0;
@@ -1142,6 +1147,7 @@ static void snapshot_dtr(struct dm_targe
 	smp_mb();
 
 #ifdef CONFIG_DM_DEBUG
+	BUG_ON(s->pending_exceptions_submitted);
 	for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
 		BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i]));
 #endif
@@ -1291,6 +1297,8 @@ static void pending_complete(struct dm_s
 	dm_insert_exception(&s->complete, e);
 
  out:
+	BUG_ON(s->pending_exceptions_submitted <= 0);
+	s->pending_exceptions_submitted--;
 	dm_remove_exception(&pe->e);
 	snapshot_bios = bio_list_get(&pe->snapshot_bios);
 	origin_bios = bio_list_get(&pe->origin_bios);
@@ -1401,6 +1409,7 @@ __find_pending_exception(struct dm_snaps
 	}
 
 	dm_insert_exception(&s->pending, &pe->e);
+	s->pending_exceptions_submitted++;
 
 	return pe;
 }