linux/include/linux/loop.h
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   1/*
   2 * include/linux/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/spinlock.h>
  15#include <linux/mutex.h>
  16#include <uapi/linux/loop.h>
  17
  18/* Possible states of device */
  19enum {
  20        Lo_unbound,
  21        Lo_bound,
  22        Lo_rundown,
  23};
  24
  25struct loop_func_table;
  26
  27struct loop_device {
  28        int             lo_number;
  29        int             lo_refcnt;
  30        loff_t          lo_offset;
  31        loff_t          lo_sizelimit;
  32        int             lo_flags;
  33        int             (*transfer)(struct loop_device *, int cmd,
  34                                    struct page *raw_page, unsigned raw_off,
  35                                    struct page *loop_page, unsigned loop_off,
  36                                    int size, sector_t real_block);
  37        char            lo_file_name[LO_NAME_SIZE];
  38        char            lo_crypt_name[LO_NAME_SIZE];
  39        char            lo_encrypt_key[LO_KEY_SIZE];
  40        int             lo_encrypt_key_size;
  41        struct loop_func_table *lo_encryption;
  42        __u32           lo_init[2];
  43        kuid_t          lo_key_owner;   /* Who set the key */
  44        int             (*ioctl)(struct loop_device *, int cmd, 
  45                                 unsigned long arg); 
  46
  47        struct file *   lo_backing_file;
  48        struct block_device *lo_device;
  49        unsigned        lo_blocksize;
  50        void            *key_data; 
  51
  52        gfp_t           old_gfp_mask;
  53
  54        spinlock_t              lo_lock;
  55        struct bio_list         lo_bio_list;
  56        unsigned int            lo_bio_count;
  57        int                     lo_state;
  58        struct mutex            lo_ctl_mutex;
  59        struct task_struct      *lo_thread;
  60        wait_queue_head_t       lo_event;
  61        /* wait queue for incoming requests */
  62        wait_queue_head_t       lo_req_wait;
  63
  64        struct request_queue    *lo_queue;
  65        struct gendisk          *lo_disk;
  66};
  67
  68/* Support for loadable transfer modules */
  69struct loop_func_table {
  70        int number;     /* filter type */ 
  71        int (*transfer)(struct loop_device *lo, int cmd,
  72                        struct page *raw_page, unsigned raw_off,
  73                        struct page *loop_page, unsigned loop_off,
  74                        int size, sector_t real_block);
  75        int (*init)(struct loop_device *, const struct loop_info64 *); 
  76        /* release is called from loop_unregister_transfer or clr_fd */
  77        int (*release)(struct loop_device *); 
  78        int (*ioctl)(struct loop_device *, int cmd, unsigned long arg);
  79        struct module *owner;
  80}; 
  81
  82int loop_register_transfer(struct loop_func_table *funcs);
  83int loop_unregister_transfer(int number); 
  84
  85#endif
  86
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