root/drivers/block/loop.h

INCLUDED FROM

   1 /*
   2  * 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/blk-mq.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/mutex.h>
  17 #include <linux/kthread.h>
  18 #include <uapi/linux/loop.h>
  19 
  20 /* Possible states of device */
  21 enum {
  22         Lo_unbound,
  23         Lo_bound,
  24         Lo_rundown,
  25 };
  26 
  27 struct loop_func_table;
  28 
  29 struct loop_device {
  30         int             lo_number;
  31         atomic_t        lo_refcnt;
  32         loff_t          lo_offset;
  33         loff_t          lo_sizelimit;
  34         int             lo_flags;
  35         int             (*transfer)(struct loop_device *, int cmd,
  36                                     struct page *raw_page, unsigned raw_off,
  37                                     struct page *loop_page, unsigned loop_off,
  38                                     int size, sector_t real_block);
  39         char            lo_file_name[LO_NAME_SIZE];
  40         char            lo_crypt_name[LO_NAME_SIZE];
  41         char            lo_encrypt_key[LO_KEY_SIZE];
  42         int             lo_encrypt_key_size;
  43         struct loop_func_table *lo_encryption;
  44         __u32           lo_init[2];
  45         kuid_t          lo_key_owner;   /* Who set the key */
  46         int             (*ioctl)(struct loop_device *, int cmd, 
  47                                  unsigned long arg); 
  48 
  49         struct file *   lo_backing_file;
  50         struct block_device *lo_device;
  51         void            *key_data; 
  52 
  53         gfp_t           old_gfp_mask;
  54 
  55         spinlock_t              lo_lock;
  56         int                     lo_state;
  57         struct kthread_worker   worker;
  58         struct task_struct      *worker_task;
  59         bool                    use_dio;
  60         bool                    sysfs_inited;
  61 
  62         struct request_queue    *lo_queue;
  63         struct blk_mq_tag_set   tag_set;
  64         struct gendisk          *lo_disk;
  65 };
  66 
  67 struct loop_cmd {
  68         struct kthread_work work;
  69         bool use_aio; /* use AIO interface to handle I/O */
  70         atomic_t ref; /* only for aio */
  71         long ret;
  72         struct kiocb iocb;
  73         struct bio_vec *bvec;
  74         struct cgroup_subsys_state *css;
  75 };
  76 
  77 /* Support for loadable transfer modules */
  78 struct loop_func_table {
  79         int number;     /* filter type */ 
  80         int (*transfer)(struct loop_device *lo, int cmd,
  81                         struct page *raw_page, unsigned raw_off,
  82                         struct page *loop_page, unsigned loop_off,
  83                         int size, sector_t real_block);
  84         int (*init)(struct loop_device *, const struct loop_info64 *); 
  85         /* release is called from loop_unregister_transfer or clr_fd */
  86         int (*release)(struct loop_device *); 
  87         int (*ioctl)(struct loop_device *, int cmd, unsigned long arg);
  88         struct module *owner;
  89 }; 
  90 
  91 int loop_register_transfer(struct loop_func_table *funcs);
  92 int loop_unregister_transfer(int number); 
  93 
  94 #endif