mtd: fix master device identification for mtd repartition

Function mtd_has_master renamed as mtd_is_partition to follow the function logic.
The patch fixes the problem of checking the right mtd device for partition creation.
To delete partition checking is not needed here so as it is done in mtd_del_partition.
By master we consider the mtd device which does not belong to any partition.

Signed-off-by: Roman Tereshonkov <roman.tereshonkov@nokia.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/mtdchar.c

@@ -522,10 +522,6 @@ static int mtd_blkpg_ioctl(struct mtd_info *mtd,
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
-	/* Only master mtd device must be used to control partitions */
-	if (!mtd_is_master(mtd))
-		return -EINVAL;
-
 	if (copy_from_user(&a, arg, sizeof(struct blkpg_ioctl_arg)))
 		return -EFAULT;
 
@@ -535,6 +531,10 @@ static int mtd_blkpg_ioctl(struct mtd_info *mtd,
 	switch (a.op) {
 	case BLKPG_ADD_PARTITION:
 
+		/* Only master mtd device must be used to add partitions */
+		if (mtd_is_partition(mtd))
+			return -EINVAL;
+
 		return mtd_add_partition(mtd, p.devname, p.start, p.length);
 
 	case BLKPG_DEL_PARTITION: