1 files changed, 49 insertions, 9 deletions

diff --git a/drivers/md/dm-exception-store.h b/drivers/md/dm-exception-store.h
index bb9f33d5daa..0a2e6e7f67b 100644
--- a/drivers/md/dm-exception-store.h
+++ b/drivers/md/dm-exception-store.h
@@ -37,11 +37,18 @@ struct dm_snap_exception {
  * Abstraction to handle the meta/layout of exception stores (the
  * COW device).
  */
-struct dm_exception_store {
+struct dm_exception_store;
+struct dm_exception_store_type {
+	const char *name;
+	struct module *module;
+
+	int (*ctr) (struct dm_exception_store *store,
+		    unsigned argc, char **argv);
+
 	/*
 	 * Destroys this object when you've finished with it.
 	 */
-	void (*destroy) (struct dm_exception_store *store);
+	void (*dtr) (struct dm_exception_store *store);
 
 	/*
 	 * The target shouldn't read the COW device until this is
@@ -72,8 +79,9 @@ struct dm_exception_store {
 	 */
 	void (*drop_snapshot) (struct dm_exception_store *store);
 
-	int (*status) (struct dm_exception_store *store, status_type_t status,
-		       char *result, unsigned int maxlen);
+	unsigned (*status) (struct dm_exception_store *store,
+			    status_type_t status, char *result,
+			    unsigned maxlen);
 
 	/*
 	 * Return how full the snapshot is.
@@ -82,7 +90,21 @@ struct dm_exception_store {
 			       sector_t *numerator,
 			       sector_t *denominator);
 
-	struct dm_snapshot *snap;
+	/* For internal device-mapper use only. */
+	struct list_head list;
+};
+
+struct dm_exception_store {
+	struct dm_exception_store_type *type;
+	struct dm_target *ti;
+
+	struct dm_dev *cow;
+
+	/* Size of data blocks saved - must be a power of 2 */
+	chunk_t chunk_size;
+	chunk_t chunk_mask;
+	chunk_t chunk_shift;
+
 	void *context;
 };
 
@@ -129,6 +151,28 @@ static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e)
 
 #  endif
 
+/*
+ * Return the number of sectors in the device.
+ */
+static inline sector_t get_dev_size(struct block_device *bdev)
+{
+	return bdev->bd_inode->i_size >> SECTOR_SHIFT;
+}
+
+static inline chunk_t sector_to_chunk(struct dm_exception_store *store,
+				      sector_t sector)
+{
+	return (sector & ~store->chunk_mask) >> store->chunk_shift;
+}
+
+int dm_exception_store_type_register(struct dm_exception_store_type *type);
+int dm_exception_store_type_unregister(struct dm_exception_store_type *type);
+
+int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
+			      unsigned *args_used,
+			      struct dm_exception_store **store);
+void dm_exception_store_destroy(struct dm_exception_store *store);
+
 int dm_exception_store_init(void);
 void dm_exception_store_exit(void);
 
@@ -141,8 +185,4 @@ void dm_persistent_snapshot_exit(void);
 int dm_transient_snapshot_init(void);
 void dm_transient_snapshot_exit(void);
 
-int dm_create_persistent(struct dm_exception_store *store);
-
-int dm_create_transient(struct dm_exception_store *store);
-
 #endif /* _LINUX_DM_EXCEPTION_STORE */