root/include/linux/loop.h

INCLUDED FROM

#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              *lo_bio;
        struct bio              *lo_biotail;
        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 <asm/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

#endif