block: pass a gendisk to bdev_add_partition

bdev_add_partition can only operate on the whole device.  Make that clear
by passing a gendisk instead of a block_device.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210810154512.1809898-3-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk.h

@@ -347,8 +347,8 @@ void blk_free_ext_minor(unsigned int minor);
 #define ADDPART_FLAG_NONE	0
 #define ADDPART_FLAG_RAID	1
 #define ADDPART_FLAG_WHOLEDISK	2
-int bdev_add_partition(struct block_device *bdev, int partno,
-		sector_t start, sector_t length);
+int bdev_add_partition(struct gendisk *disk, int partno, sector_t start,
+		sector_t length);
 int bdev_del_partition(struct block_device *bdev, int partno);
 int bdev_resize_partition(struct block_device *bdev, int partno,
 		sector_t start, sector_t length);

block/ioctl.c

@@ -16,6 +16,7 @@
 static int blkpg_do_ioctl(struct block_device *bdev,
 			  struct blkpg_partition __user *upart, int op)
 {
+	struct gendisk *disk = bdev->bd_disk;
 	struct blkpg_partition p;
 	long long start, length;
 
@@ -40,7 +41,7 @@ static int blkpg_do_ioctl(struct block_device *bdev,
 		/* check if partition is aligned to blocksize */
 		if (p.start & (bdev_logical_block_size(bdev) - 1))
 			return -EINVAL;
-		return bdev_add_partition(bdev, p.pno, start, length);
+		return bdev_add_partition(disk, p.pno, start, length);
 	case BLKPG_RESIZE_PARTITION:
 		return bdev_resize_partition(bdev, p.pno, start, length);
 	default:

block/partitions/core.c

@@ -451,11 +451,10 @@ static bool partition_overlaps(struct gendisk *disk, sector_t start,
 	return overlap;
 }
 
-int bdev_add_partition(struct block_device *bdev, int partno,
-		sector_t start, sector_t length)
+int bdev_add_partition(struct gendisk *disk, int partno, sector_t start,
+		sector_t length)
 {
 	struct block_device *part;
-	struct gendisk *disk = bdev->bd_disk;
 	int ret;
 
 	mutex_lock(&disk->open_mutex);