include/linux/device-mapper.h

   1 /*
   2  * Copyright (C) 2001 Sistina Software (UK) Limited.
   3  *
   4  * This file is released under the LGPL.
   5  */
   6
   7 #ifndef _LINUX_DEVICE_MAPPER_H
   8 #define _LINUX_DEVICE_MAPPER_H
   9
  10 struct dm_target;
  11 struct dm_table;
  12 struct dm_dev;
  13
  14 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  15
  16 union map_info {
  17         void *ptr;
  18         unsigned long long ll;
  19 };
  20
  21 /*
  22  * In the constructor the target parameter will already have the
  23  * table, type, begin and len fields filled in.
  24  */
  25 typedef int (*dm_ctr_fn) (struct dm_target *target,
  26                           unsigned int argc, char **argv);
  27
  28 /*
  29  * The destructor doesn't need to free the dm_target, just
  30  * anything hidden ti->private.
  31  */
  32 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  33
  34 /*
  35  * The map function must return:
  36  * < 0: error
  37  * = 0: The target will handle the io by resubmitting it later
  38  * > 0: simple remap complete
  39  */
  40 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
  41                           union map_info *map_context);
  42
  43 /*
  44  * Returns:
  45  * < 0 : error (currently ignored)
  46  * 0   : ended successfully
  47  * 1   : for some reason the io has still not completed (eg,
  48  *       multipath target might want to requeue a failed io).
  49  */
  50 typedef int (*dm_endio_fn) (struct dm_target *ti,
  51                             struct bio *bio, int error,
  52                             union map_info *map_context);
  53
  54 typedef void (*dm_suspend_fn) (struct dm_target *ti);
  55 typedef void (*dm_resume_fn) (struct dm_target *ti);
  56
  57 typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  58                              char *result, unsigned int maxlen);
  59
  60 void dm_error(const char *message);
  61
  62 /*
  63  * Constructors should call these functions to ensure destination devices
  64  * are opened/closed correctly.
  65  * FIXME: too many arguments.
  66  */
  67 int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
  68                   sector_t len, int mode, struct dm_dev **result);
  69 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
  70
  71 /*
  72  * Information about a target type
  73  */
  74 struct target_type {
  75         const char *name;
  76         struct module *module;
  77         unsigned version[3];
  78         dm_ctr_fn ctr;
  79         dm_dtr_fn dtr;
  80         dm_map_fn map;
  81         dm_endio_fn end_io;
  82         dm_suspend_fn suspend;
  83         dm_resume_fn resume;
  84         dm_status_fn status;
  85 };
  86
  87 struct io_restrictions {
  88         unsigned short          max_sectors;
  89         unsigned short          max_phys_segments;
  90         unsigned short          max_hw_segments;
  91         unsigned short          hardsect_size;
  92         unsigned int            max_segment_size;
  93         unsigned long           seg_boundary_mask;
  94 };
  95
  96 struct dm_target {
  97         struct dm_table *table;
  98         struct target_type *type;
  99
 100         /* target limits */
 101         sector_t begin;
 102         sector_t len;
 103
 104         /* FIXME: turn this into a mask, and merge with io_restrictions */
 105         sector_t split_io;
 106
 107         /*
 108          * These are automatically filled in by
 109          * dm_table_get_device.
 110          */
 111         struct io_restrictions limits;
 112
 113         /* target specific data */
 114         void *private;
 115
 116         /* Used to provide an error string from the ctr */
 117         char *error;
 118 };
 119
 120 int dm_register_target(struct target_type *t);
 121 int dm_unregister_target(struct target_type *t);
 122
 123 #endif                          /* _LINUX_DEVICE_MAPPER_H */