target/iblock: use bdev_nr_bytes instead of open coding it

Use the proper helper to read the block device size.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20211018101130.1838532-9-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/target/target_core_iblock.c

@@ -232,9 +232,9 @@ static unsigned long long iblock_emulate_read_cap_with_block_size(
 	struct block_device *bd,
 	struct request_queue *q)
 {
-	unsigned long long blocks_long = (div_u64(i_size_read(bd->bd_inode),
-					bdev_logical_block_size(bd)) - 1);
 	u32 block_size = bdev_logical_block_size(bd);
+	unsigned long long blocks_long =
+		div_u64(bdev_nr_bytes(bd), block_size) - 1;
 
 	if (block_size == dev->dev_attrib.block_size)
 		return blocks_long;