btrfs: pass NULL index to btrfs_del_inode_ref() where not needed

There are two callers of btrfs_del_inode_ref() that declare a local index
variable and then pass a pointer for it to btrfs_del_inode_ref(), but then
don't use that index at all. Since btrfs_del_inode_ref() accepts a NULL
index pointer, pass NULL instead and stop declaring those useless index
variables.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: fdmanana

fs/btrfs/inode.c

@@ -6711,10 +6711,9 @@ int btrfs_add_link(struct btrfs_trans_handle *trans,
 		if (ret2)
 			btrfs_abort_transaction(trans, ret2);
 	} else if (add_backref) {
-		u64 local_index;
 		int ret2;
 
-		ret2 = btrfs_del_inode_ref(trans, root, name, ino, parent_ino, &local_index);
+		ret2 = btrfs_del_inode_ref(trans, root, name, ino, parent_ino, NULL);
 		if (ret2)
 			btrfs_abort_transaction(trans, ret2);
 	}

fs/btrfs/tree-log.c

@@ -3502,7 +3502,6 @@ void btrfs_del_inode_ref_in_log(struct btrfs_trans_handle *trans,
 				struct btrfs_inode *inode, u64 dirid)
 {
 	struct btrfs_root *log;
-	u64 index;
 	int ret;
 
 	ret = inode_logged(trans, inode, NULL);
@@ -3520,8 +3519,7 @@ void btrfs_del_inode_ref_in_log(struct btrfs_trans_handle *trans,
 	log = root->log_root;
 	mutex_lock(&inode->log_mutex);
 
-	ret = btrfs_del_inode_ref(trans, log, name, btrfs_ino(inode),
-				  dirid, &index);
+	ret = btrfs_del_inode_ref(trans, log, name, btrfs_ino(inode), dirid, NULL);
 	mutex_unlock(&inode->log_mutex);
 	if (ret < 0 && ret != -ENOENT)
 		btrfs_set_log_full_commit(trans);