drivers/block/loop.h

   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 mutex            lo_ctl_mutex;
  58         struct kthread_worker   worker;
  59         struct task_struct      *worker_task;
  60         bool                    use_dio;
  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         struct request *rq;
  70         bool use_aio; /* use AIO interface to handle I/O */
  71         atomic_t ref; /* only for aio */
  72         long ret;
  73         struct kiocb iocb;
  74         struct bio_vec *bvec;
  75         struct cgroup_subsys_state *css;
  76 };
  77
  78 /* Support for loadable transfer modules */
  79 struct loop_func_table {
  80         int number;     /* filter type */
  81         int (*transfer)(struct loop_device *lo, int cmd,
  82                         struct page *raw_page, unsigned raw_off,
  83                         struct page *loop_page, unsigned loop_off,
  84                         int size, sector_t real_block);
  85         int (*init)(struct loop_device *, const struct loop_info64 *);
  86         /* release is called from loop_unregister_transfer or clr_fd */
  87         int (*release)(struct loop_device *);
  88         int (*ioctl)(struct loop_device *, int cmd, unsigned long arg);
  89         struct module *owner;
  90 };
  91
  92 int loop_register_transfer(struct loop_func_table *funcs);
  93 int loop_unregister_transfer(int number);
  94
  95 #endif