rbd: RBD_V{1,2}_DATA_FORMAT macros

... and also fix up the comment -- format 1 data objects have always
been 12 hex digits long.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Jason Dillaman <dillaman@redhat.com>

drivers/block/rbd.c

@@ -1257,18 +1257,16 @@ static void rbd_segment_name_free(const char *name)
 
 static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
 {
+	const char *name_format = rbd_dev->image_format == 1 ?
+				      RBD_V1_DATA_FORMAT : RBD_V2_DATA_FORMAT;
 	char *name;
 	u64 segment;
 	int ret;
-	char *name_format;
 
 	name = kmem_cache_alloc(rbd_segment_name_cache, GFP_NOIO);
 	if (!name)
 		return NULL;
 	segment = offset >> rbd_dev->header.obj_order;
-	name_format = "%s.%012llx";
-	if (rbd_dev->image_format == 2)
-		name_format = "%s.%016llx";
 	ret = snprintf(name, CEPH_MAX_OID_NAME_LEN + 1, name_format,
 			rbd_dev->header.object_prefix, segment);
 	if (ret < 0 || ret > CEPH_MAX_OID_NAME_LEN) {

drivers/block/rbd_types.h

@@ -25,8 +25,8 @@
  */
 
 #define RBD_HEADER_PREFIX      "rbd_header."
-#define RBD_DATA_PREFIX        "rbd_data."
 #define RBD_ID_PREFIX          "rbd_id."
+#define RBD_V2_DATA_FORMAT     "%s.%016llx"
 
 #define RBD_LOCK_NAME          "rbd_lock"
 #define RBD_LOCK_TAG           "internal"
@@ -42,13 +42,14 @@ enum rbd_notify_op {
 /*
  * For format version 1, rbd image 'foo' consists of objects
  *   foo.rbd		- image metadata
- *   rb.<idhi>.<idlo>.00000000
- *   rb.<idhi>.<idlo>.00000001
+ *   rb.<idhi>.<idlo>.<extra>.000000000000
+ *   rb.<idhi>.<idlo>.<extra>.000000000001
  *   ...		- data
  * There is no notion of a persistent image id in rbd format 1.
  */
 
 #define RBD_SUFFIX		".rbd"
+#define RBD_V1_DATA_FORMAT	"%s.%012llx"
 
 #define RBD_DIRECTORY           "rbd_directory"
 #define RBD_INFO                "rbd_info"