#ifndef _LINUX_LOOP_H
  #define _LINUX_LOOP_H
  
  /*
   * include/linux/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.
   */
  
  #define LO_NAME_SIZE	64
  #define LO_KEY_SIZE	32
  
  #ifdef __KERNEL__
  #include <linux/bio.h>
  #include <linux/blkdev.h>
  #include <linux/spinlock.h>

  #include <linux/mutex.h>

  
  /* Possible states of device */
  enum {
  	Lo_unbound,
  	Lo_bound,
  	Lo_rundown,
  };
  
  struct loop_func_table;
  
  struct loop_device {
  	int		lo_number;
  	int		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];
  	uid_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;
  	unsigned	lo_blocksize;
  	void		*key_data; 

  	gfp_t		old_gfp_mask;

  
  	spinlock_t		lo_lock;

  	struct bio_list		lo_bio_list;

  	int			lo_state;

  	struct mutex		lo_ctl_mutex;

  	struct task_struct	*lo_thread;
  	wait_queue_head_t	lo_event;

  	struct request_queue	*lo_queue;

  	struct gendisk		*lo_disk;
  	struct list_head	lo_list;

  };
  
  #endif /* __KERNEL__ */
  
  /*
   * Loop flags
   */
  enum {
  	LO_FLAGS_READ_ONLY	= 1,
  	LO_FLAGS_USE_AOPS	= 2,

  	LO_FLAGS_AUTOCLEAR	= 4,

  };
  
  #include <asm/posix_types.h>	/* for __kernel_old_dev_t */

  #include <linux/types.h>	/* for __u64 */

  
  /* Backwards compatibility version */
  struct loop_info {
  	int		   lo_number;		/* ioctl r/o */
  	__kernel_old_dev_t lo_device; 		/* ioctl r/o */
  	unsigned long	   lo_inode; 		/* ioctl r/o */
  	__kernel_old_dev_t lo_rdevice; 		/* ioctl r/o */
  	int		   lo_offset;
  	int		   lo_encrypt_type;
  	int		   lo_encrypt_key_size; 	/* ioctl w/o */
  	int		   lo_flags;			/* ioctl r/o */
  	char		   lo_name[LO_NAME_SIZE];
  	unsigned char	   lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
  	unsigned long	   lo_init[2];
  	char		   reserved[4];
  };
  
  struct loop_info64 {
  	__u64		   lo_device;			/* ioctl r/o */
  	__u64		   lo_inode;			/* ioctl r/o */
  	__u64		   lo_rdevice;			/* ioctl r/o */
  	__u64		   lo_offset;
  	__u64		   lo_sizelimit;/* bytes, 0 == max available */
  	__u32		   lo_number;			/* ioctl r/o */
  	__u32		   lo_encrypt_type;
  	__u32		   lo_encrypt_key_size;		/* ioctl w/o */
  	__u32		   lo_flags;			/* ioctl r/o */
  	__u8		   lo_file_name[LO_NAME_SIZE];
  	__u8		   lo_crypt_name[LO_NAME_SIZE];
  	__u8		   lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
  	__u64		   lo_init[2];
  };
  
  /*
   * Loop filter types
   */
  
  #define LO_CRYPT_NONE		0
  #define LO_CRYPT_XOR		1
  #define LO_CRYPT_DES		2
  #define LO_CRYPT_FISH2		3    /* Twofish encryption */
  #define LO_CRYPT_BLOW		4
  #define LO_CRYPT_CAST128	5
  #define LO_CRYPT_IDEA		6
  #define LO_CRYPT_DUMMY		9
  #define LO_CRYPT_SKIPJACK	10
  #define LO_CRYPT_CRYPTOAPI	18
  #define MAX_LO_CRYPT		20
  
  #ifdef __KERNEL__
  /* 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
  /*
   * IOCTL commands --- we will commandeer 0x4C ('L')
   */
  
  #define LOOP_SET_FD		0x4C00
  #define LOOP_CLR_FD		0x4C01
  #define LOOP_SET_STATUS		0x4C02
  #define LOOP_GET_STATUS		0x4C03
  #define LOOP_SET_STATUS64	0x4C04
  #define LOOP_GET_STATUS64	0x4C05
  #define LOOP_CHANGE_FD		0x4C06

  #define LOOP_SET_CAPACITY	0x4C07

  
  #endif