btrfs: remove unused btrfs_dio_private::private

We haven't used this since commit 9be3395bcd4a ("Btrfs: use a btrfs
bioset instead of abusing bio internals").

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 27a1fef..ad36685 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -301,7 +301,6 @@ struct btrfs_dio_private {
 	u64 logical_offset;
 	u64 disk_bytenr;
 	u64 bytes;
-	void *private;
 
 	/* number of bios pending for this dio */
 	atomic_t pending_bios;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index b32970d..6a240d8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7923,7 +7923,6 @@ static struct btrfs_dio_private *btrfs_create_dio_private(struct bio *dio_bio,
 	bio->bi_private = dip;
 	btrfs_io_bio(bio)->logical = file_offset;
 
-	dip->private = dio_bio->bi_private;
 	dip->inode = inode;
 	dip->logical_offset = file_offset;
 	dip->bytes = dio_bio->bi_iter.bi_size;