drivers/md/md.c

1191  *   int load_super(struct md_rdev *dev, struct md_rdev *refdev, int minor_version)
1193  *      if refdev != NULL, compare superblocks on both devices
1195  *      0 - dev has a superblock that is compatible with refdev
1196  *      1 - dev has a superblock that is compatible and newer than refdev
1197  *          so dev should be used as the refdev in future
1217 					  struct md_rdev *refdev,
1251 static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)
1308 	if (!refdev) {
1315 		mdp_super_t *refsb = page_address(refdev->sb_page);
1318 				rdev->bdev, refdev->bdev);
1323 				rdev->bdev, refdev->bdev);
1691 static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)
1834 	if (!refdev) {
1841 		struct mdp_superblock_1 *refsb = page_address(refdev->sb_page);
1849 				refdev->bdev);