+struct dm_snap_tracked_chunk {
+ struct hlist_node node;
+ chunk_t chunk;
+};
+
+static struct kmem_cache *tracked_chunk_cache;
+
+static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s,
+ chunk_t chunk)
+{
+ struct dm_snap_tracked_chunk *c = mempool_alloc(s->tracked_chunk_pool,
+ GFP_NOIO);
+ unsigned long flags;
+
+ c->chunk = chunk;
+
+ spin_lock_irqsave(&s->tracked_chunk_lock, flags);
+ hlist_add_head(&c->node,
+ &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]);
+ spin_unlock_irqrestore(&s->tracked_chunk_lock, flags);
+
+ return c;
+}
+
+static void stop_tracking_chunk(struct dm_snapshot *s,
+ struct dm_snap_tracked_chunk *c)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&s->tracked_chunk_lock, flags);
+ hlist_del(&c->node);
+ spin_unlock_irqrestore(&s->tracked_chunk_lock, flags);
+
+ mempool_free(c, s->tracked_chunk_pool);
+}
+