dm snapshot: move status to exception store

Let the exception store types print out their status through
the new API, rather than having the snapshot code do it.

Adjust the buffer position to allow for the preceding DMEMIT in the
arguments to type->status().
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

drivers/md/dm-exception-store.h

@@ -79,8 +79,9 @@ struct dm_exception_store_type {
 	 */
 	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.

drivers/md/dm-snap-persistent.c

@@ -688,11 +688,19 @@ static int persistent_ctr(struct dm_exception_store *store,
 	return 0;
 }
 
-static int persistent_status(struct dm_exception_store *store,
-			     status_type_t status, char *result,
-			     unsigned int maxlen)
+static unsigned persistent_status(struct dm_exception_store *store,
+				  status_type_t status, char *result,
+				  unsigned maxlen)
 {
-	int sz = 0;
+	unsigned sz = 0;
+
+	switch (status) {
+	case STATUSTYPE_INFO:
+		break;
+	case STATUSTYPE_TABLE:
+		DMEMIT(" %s P %llu", store->cow->name,
+		       (unsigned long long)store->chunk_size);
+	}
 
 	return sz;
 }

drivers/md/dm-snap-transient.c

@@ -81,11 +81,19 @@ static int transient_ctr(struct dm_exception_store *store,
 	return 0;
 }
 
-static int transient_status(struct dm_exception_store *store,
-			    status_type_t status, char *result,
-			    unsigned maxlen)
+static unsigned transient_status(struct dm_exception_store *store,
+				 status_type_t status, char *result,
+				 unsigned maxlen)
 {
-	int sz = 0;
+	unsigned sz = 0;
+
+	switch (status) {
+	case STATUSTYPE_INFO:
+		break;
+	case STATUSTYPE_TABLE:
+		DMEMIT(" %s N %llu", store->cow->name,
+		       (unsigned long long)store->chunk_size);
+	}
 
 	return sz;
 }

drivers/md/dm-snap.c

@@ -70,9 +70,6 @@ struct dm_snapshot {
 	/* Origin writes don't trigger exceptions until this is set */
 	int active;
 
-	/* Used for display of table */
-	char type;
-
 	mempool_t *pending_pool;
 
 	atomic_t pending_exceptions_count;
@@ -1166,9 +1163,8 @@ static int snapshot_status(struct dm_target *ti, status_type_t type,
 		 * make sense.
 		 */
 		DMEMIT("%s", snap->origin->name);
-		DMEMIT(" %s %s %llu", snap->store->cow->name,
-		       snap->store->type->name,
-		       (unsigned long long)snap->store->chunk_size);
+		snap->store->type->status(snap->store, type, result + sz,
+					  maxlen - sz);
 		break;
 	}