include/linux/device-mapper.h

   1 /*
   2  * Copyright (C) 2001 Sistina Software (UK) Limited.
   3  * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
   4  *
   5  * This file is released under the LGPL.
   6  */
   7
   8 #ifndef _LINUX_DEVICE_MAPPER_H
   9 #define _LINUX_DEVICE_MAPPER_H
  10
  11 struct dm_target;
  12 struct dm_table;
  13 struct dm_dev;
  14
  15 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  16
  17 union map_info {
  18         void *ptr;
  19         unsigned long long ll;
  20 };
  21
  22 /*
  23  * In the constructor the target parameter will already have the
  24  * table, type, begin and len fields filled in.
  25  */
  26 typedef int (*dm_ctr_fn) (struct dm_target *target,
  27                           unsigned int argc, char **argv);
  28
  29 /*
  30  * The destructor doesn't need to free the dm_target, just
  31  * anything hidden ti->private.
  32  */
  33 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  34
  35 /*
  36  * The map function must return:
  37  * < 0: error
  38  * = 0: The target will handle the io by resubmitting it later
  39  * > 0: simple remap complete
  40  */
  41 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
  42                           union map_info *map_context);
  43
  44 /*
  45  * Returns:
  46  * < 0 : error (currently ignored)
  47  * 0   : ended successfully
  48  * 1   : for some reason the io has still not completed (eg,
  49  *       multipath target might want to requeue a failed io).
  50  */
  51 typedef int (*dm_endio_fn) (struct dm_target *ti,
  52                             struct bio *bio, int error,
  53                             union map_info *map_context);
  54
  55 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  56 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  57 typedef void (*dm_resume_fn) (struct dm_target *ti);
  58
  59 typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  60                              char *result, unsigned int maxlen);
  61
  62 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  63
  64 void dm_error(const char *message);
  65
  66 /*
  67  * Constructors should call these functions to ensure destination devices
  68  * are opened/closed correctly.
  69  * FIXME: too many arguments.
  70  */
  71 int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
  72                   sector_t len, int mode, struct dm_dev **result);
  73 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
  74
  75 /*
  76  * Information about a target type
  77  */
  78 struct target_type {
  79         const char *name;
  80         struct module *module;
  81         unsigned version[3];
  82         dm_ctr_fn ctr;
  83         dm_dtr_fn dtr;
  84         dm_map_fn map;
  85         dm_endio_fn end_io;
  86         dm_presuspend_fn presuspend;
  87         dm_postsuspend_fn postsuspend;
  88         dm_resume_fn resume;
  89         dm_status_fn status;
  90         dm_message_fn message;
  91 };
  92
  93 struct io_restrictions {
  94         unsigned short          max_sectors;
  95         unsigned short          max_phys_segments;
  96         unsigned short          max_hw_segments;
  97         unsigned short          hardsect_size;
  98         unsigned int            max_segment_size;
  99         unsigned long           seg_boundary_mask;
 100 };
 101
 102 struct dm_target {
 103         struct dm_table *table;
 104         struct target_type *type;
 105
 106         /* target limits */
 107         sector_t begin;
 108         sector_t len;
 109
 110         /* FIXME: turn this into a mask, and merge with io_restrictions */
 111         /* Always a power of 2 */
 112         sector_t split_io;
 113
 114         /*
 115          * These are automatically filled in by
 116          * dm_table_get_device.
 117          */
 118         struct io_restrictions limits;
 119
 120         /* target specific data */
 121         void *private;
 122
 123         /* Used to provide an error string from the ctr */
 124         char *error;
 125 };
 126
 127 int dm_register_target(struct target_type *t);
 128 int dm_unregister_target(struct target_type *t);
 129
 130 #endif                          /* _LINUX_DEVICE_MAPPER_H */