-/*
- * The snapshot code deals with largish chunks of the disk at a
- * time. Typically 64k - 256k.
- */
-/* FIXME: can we get away with limiting these to a uint32_t ? */
-typedef sector_t chunk_t;
-
-/*
- * An exception is used where an old chunk of data has been
- * replaced by a new one.
- */
-struct dm_snap_exception {
- struct list_head hash_list;
-
- chunk_t old_chunk;
- chunk_t new_chunk;
-};
-
-/*
- * Abstraction to handle the meta/layout of exception stores (the
- * COW device).
- */
-struct exception_store {
-
- /*
- * Destroys this object when you've finished with it.
- */
- void (*destroy) (struct exception_store *store);
-
- /*
- * The target shouldn't read the COW device until this is
- * called.
- */
- int (*read_metadata) (struct exception_store *store);
-
- /*
- * Find somewhere to store the next exception.
- */
- int (*prepare_exception) (struct exception_store *store,
- struct dm_snap_exception *e);
-
- /*
- * Update the metadata with this exception.
- */
- void (*commit_exception) (struct exception_store *store,
- struct dm_snap_exception *e,
- void (*callback) (void *, int success),
- void *callback_context);
-
- /*
- * The snapshot is invalid, note this in the metadata.
- */
- void (*drop_snapshot) (struct exception_store *store);
-
- /*
- * Return how full the snapshot is.
- */
- void (*fraction_full) (struct exception_store *store,
- sector_t *numerator,
- sector_t *denominator);
-
- struct dm_snapshot *snap;
- void *context;
-};