dm snapshot: extend exception store functions

Supply dm_add_exception as a callback to the read_metadata function.
Add a status function ready for a later patch and name the functions
consistently.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/drivers/md/dm-exception-store.h b/drivers/md/dm-exception-store.h
index 78d1acec77e9..bb9f33d5daa2 100644
--- a/drivers/md/dm-exception-store.h
+++ b/drivers/md/dm-exception-store.h
@@ -11,6 +11,7 @@
 #define _LINUX_DM_EXCEPTION_STORE
 
 #include <linux/blkdev.h>
+#include <linux/device-mapper.h>
 
 /*
  * The snapshot code deals with largish chunks of the disk at a
@@ -37,7 +38,6 @@ struct dm_snap_exception {
  * COW device).
  */
 struct dm_exception_store {
-
         /*
          * Destroys this object when you've finished with it.
          */
@@ -45,9 +45,13 @@ struct dm_exception_store {
 
         /*
          * The target shouldn't read the COW device until this is
-         * called.
+         * called.  As exceptions are read from the COW, they are
+         * reported back via the callback.
          */
-        int (*read_metadata) (struct dm_exception_store *store);
+        int (*read_metadata) (struct dm_exception_store *store,
+                              int (*callback)(void *callback_context,
+                                              chunk_t old, chunk_t new),
+                              void *callback_context);
 
         /*
          * Find somewhere to store the next exception.
@@ -68,6 +72,9 @@ 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);
+
         /*
          * Return how full the snapshot is.
          */