#ifndef _LINUX_LOOP_H#define _LINUX_LOOP_H#include <linux/kdev_t.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__/* Possible states of device */enum {	Lo_unbound,	Lo_bound,	Lo_rundown,};struct loop_device {	int		lo_number;	int		lo_refcnt;	kdev_t		lo_device;	int		lo_offset;	int		lo_encrypt_type;	int		lo_encrypt_key_size;	int		lo_flags;	int		(*transfer)(struct loop_device *, int cmd,				    char *raw_buf, char *loop_buf, int size,				    int real_block);	char		lo_name[LO_NAME_SIZE];	char		lo_encrypt_key[LO_KEY_SIZE];	__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;	void		*key_data; 	char		key_reserved[48]; /* for use by the filter modules */	int		old_gfp_mask;	spinlock_t		lo_lock;	struct buffer_head	*lo_bh;	struct buffer_head	*lo_bhtail;	int			lo_state;	struct semaphore	lo_sem;	struct semaphore	lo_ctl_mutex;	struct semaphore	lo_bh_mutex;	atomic_t		lo_pending;};typedef	int (* transfer_proc_t)(struct loop_device *, int cmd,				char *raw_buf, char *loop_buf, int size,				int real_block);static inline int lo_do_transfer(struct loop_device *lo, int cmd, char *rbuf,				 char *lbuf, int size, int rblock){	if (!lo->transfer)		return 0;	return lo->transfer(lo, cmd, rbuf, lbuf, size, rblock);}#endif /* __KERNEL__ *//* * Loop flags */#define LO_FLAGS_DO_BMAP	1#define LO_FLAGS_READ_ONLY	2#define LO_FLAGS_BH_REMAP	4/*  * Note that this structure gets the wrong offsets when directly used * from a glibc program, because glibc has a 32bit dev_t. * Prevent people from shooting in their own foot.   */#if __GLIBC__ >= 2 && !defined(dev_t)#error "Wrong dev_t in loop.h"#endif /* *	This uses kdev_t because glibc currently has no appropiate *	conversion version for the loop ioctls.  * 	The situation is very unpleasant	 */struct loop_info {	int		lo_number;	/* ioctl r/o */	dev_t		lo_device; 	/* ioctl r/o */	unsigned long	lo_inode; 	/* ioctl r/o */	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];};/* * Loop filter types */#define LO_CRYPT_NONE	  0#define LO_CRYPT_XOR	  1#define LO_CRYPT_DES	  2#define LO_CRYPT_FISH2    3    /* Brand new 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 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, char *raw_buf,			char *loop_buf, int size, int real_block);	int (*init)(struct loop_device *, struct loop_info *); 	/* 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);	/* lock and unlock manage the module use counts */ 	void (*lock)(struct loop_device *);	void (*unlock)(struct loop_device *);}; 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#endif