1/*
  2 * loop.h
  3 *
  4 * Written by Theodore Ts'o, 3/29/93.
  5 *
  6 * Copyright 1993 by Theodore Ts'o.  Redistribution of this file is
  7 * permitted under the GNU General Public License.
  8 */
  9#ifndef _LINUX_LOOP_H
 10#define _LINUX_LOOP_H
 11
 12#include <linux/bio.h>
 13#include <linux/blkdev.h>
 14#include <linux/blk-mq.h>
 15#include <linux/spinlock.h>
 16#include <linux/mutex.h>
 17#include <uapi/linux/loop.h>
 18
 19/* Possible states of device */
 20enum {
 21	Lo_unbound,
 22	Lo_bound,
 23	Lo_rundown,
 24	Lo_deleting,
 25};
 26
 27struct loop_func_table;
 28
 29struct loop_device {
 30	int		lo_number;
 31	atomic_t	lo_refcnt;
 32	loff_t		lo_offset;
 33	loff_t		lo_sizelimit;
 34	int		lo_flags;
 35	int		(*transfer)(struct loop_device *, int cmd,
 36				    struct page *raw_page, unsigned raw_off,
 37				    struct page *loop_page, unsigned loop_off,
 38				    int size, sector_t real_block);
 39	char		lo_file_name[LO_NAME_SIZE];
 40	char		lo_crypt_name[LO_NAME_SIZE];
 41	char		lo_encrypt_key[LO_KEY_SIZE];
 42	int		lo_encrypt_key_size;
 43	struct loop_func_table *lo_encryption;
 44	__u32           lo_init[2];
 45	kuid_t		lo_key_owner;	/* Who set the key */
 46	int		(*ioctl)(struct loop_device *, int cmd, 
 47				 unsigned long arg); 
 48
 49	struct file *	lo_backing_file;
 50	struct block_device *lo_device;
 51	void		*key_data; 
 52
 53	gfp_t		old_gfp_mask;
 54
 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;
 65	bool			sysfs_inited;
 66
 67	struct request_queue	*lo_queue;
 68	struct blk_mq_tag_set	tag_set;
 69	struct gendisk		*lo_disk;
 70	struct mutex		lo_mutex;
 71	bool			idr_visible;
 72};
 73
 74struct loop_cmd {
 75	struct list_head list_entry;
 76	bool use_aio; /* use AIO interface to handle I/O */
 77	atomic_t ref; /* only for aio */
 78	long ret;
 79	struct kiocb iocb;
 80	struct bio_vec *bvec;
 81	struct cgroup_subsys_state *blkcg_css;
 82	struct cgroup_subsys_state *memcg_css;
 83};
 84
 85/* Support for loadable transfer modules */
 86struct loop_func_table {
 87	int number;	/* filter type */ 
 88	int (*transfer)(struct loop_device *lo, int cmd,
 89			struct page *raw_page, unsigned raw_off,
 90			struct page *loop_page, unsigned loop_off,
 91			int size, sector_t real_block);
 92	int (*init)(struct loop_device *, const struct loop_info64 *); 
 93	/* release is called from loop_unregister_transfer or clr_fd */
 94	int (*release)(struct loop_device *); 
 95	int (*ioctl)(struct loop_device *, int cmd, unsigned long arg);
 96	struct module *owner;
 97}; 
 98
 99int loop_register_transfer(struct loop_func_table *funcs);
100int loop_unregister_transfer(int number); 
101
102#endif