btrfs: remove the disk_bytenr in struct btrfs_dio_private

This field is never used, so remove it. Last use was probably in
23ea8e5a ("Btrfs: load checksum data once when submitting a direct
read io").
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/btrfs_inode.h

@@ -403,7 +403,6 @@ struct btrfs_dio_private {
 	 * grab the file offset, thus need a dedicated member for file offset.
 	 */
 	u64 file_offset;
-	u64 disk_bytenr;
 	/* Used for bio::bi_size */
 	u32 bytes;
 

fs/btrfs/inode.c

@@ -8002,7 +8002,6 @@ static struct btrfs_dio_private *btrfs_create_dio_private(struct bio *dio_bio,
 	dip->inode = inode;
 	dip->file_offset = file_offset;
 	dip->bytes = dio_bio->bi_iter.bi_size;
-	dip->disk_bytenr = dio_bio->bi_iter.bi_sector << 9;
 	dip->dio_bio = dio_bio;
 	refcount_set(&dip->refs, 1);
 	return dip;