/*

   * loop.h

   *
   * Written by Theodore Ts'o, 3/29/93.
   *
   * Copyright 1993 by Theodore Ts'o.  Redistribution of this file is
   * permitted under the GNU General Public License.
   */

  #ifndef _LINUX_LOOP_H
  #define _LINUX_LOOP_H

  #include <linux/bio.h>
  #include <linux/blkdev.h>

  #include <linux/blk-mq.h>

  #include <linux/spinlock.h>

  #include <linux/mutex.h>

  #include <linux/kthread.h>

  #include <uapi/linux/loop.h>

  
  /* Possible states of device */
  enum {
  	Lo_unbound,
  	Lo_bound,
  	Lo_rundown,
  };
  
  struct loop_func_table;
  
  struct loop_device {
  	int		lo_number;

  	atomic_t	lo_refcnt;

  	loff_t		lo_offset;
  	loff_t		lo_sizelimit;
  	int		lo_flags;
  	int		(*transfer)(struct loop_device *, int cmd,
  				    struct page *raw_page, unsigned raw_off,
  				    struct page *loop_page, unsigned loop_off,
  				    int size, sector_t real_block);
  	char		lo_file_name[LO_NAME_SIZE];
  	char		lo_crypt_name[LO_NAME_SIZE];
  	char		lo_encrypt_key[LO_KEY_SIZE];
  	int		lo_encrypt_key_size;
  	struct loop_func_table *lo_encryption;
  	__u32           lo_init[2];

  	kuid_t		lo_key_owner;	/* Who set the key */

  	int		(*ioctl)(struct loop_device *, int cmd, 
  				 unsigned long arg); 
  
  	struct file *	lo_backing_file;
  	struct block_device *lo_device;

  	void		*key_data; 

  	gfp_t		old_gfp_mask;

  
  	spinlock_t		lo_lock;

  	int			lo_state;

  	struct kthread_worker	worker;
  	struct task_struct	*worker_task;

  	bool			use_dio;

  	bool			sysfs_inited;

  	struct request_queue	*lo_queue;

  	struct blk_mq_tag_set	tag_set;

  	struct gendisk		*lo_disk;

  };

  struct loop_cmd {

  	struct kthread_work work;

  	bool use_aio; /* use AIO interface to handle I/O */
  	atomic_t ref; /* only for aio */

  	long ret;

  	struct kiocb iocb;

  	struct bio_vec *bvec;

  	struct cgroup_subsys_state *css;

  };

  /* Support for loadable transfer modules */
  struct loop_func_table {
  	int number;	/* filter type */ 
  	int (*transfer)(struct loop_device *lo, int cmd,
  			struct page *raw_page, unsigned raw_off,
  			struct page *loop_page, unsigned loop_off,
  			int size, sector_t real_block);
  	int (*init)(struct loop_device *, const struct loop_info64 *); 
  	/* release is called from loop_unregister_transfer or clr_fd */
  	int (*release)(struct loop_device *); 
  	int (*ioctl)(struct loop_device *, int cmd, unsigned long arg);
  	struct module *owner;
  }; 
  
  int loop_register_transfer(struct loop_func_table *funcs);
  int loop_unregister_transfer(int number); 
  
  #endif