29 struct loop_device {  struct
35 	int		(*transfer)(struct loop_device *, int cmd,  argument
46 	int		(*ioctl)(struct loop_device *, int cmd,   argument
49 	struct file *	lo_backing_file;
50 	struct block_device *lo_device;
51 	void		*key_data; 
53 	gfp_t		old_gfp_mask;
55 	spinlock_t		lo_lock;
56 	int			lo_state;
57 	spinlock_t              lo_work_lock;
58 	struct workqueue_struct *workqueue;
59 	struct work_struct      rootcg_work;
60 	struct list_head        rootcg_cmd_list;
61 	struct list_head        idle_worker_list;
62 	struct rb_root          worker_tree;
63 	struct timer_list       timer;
64 	bool			use_dio;
88 	int (*transfer)(struct loop_device *lo, int cmd,  argument