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 #ifdef __KERNEL__
  12
  13 struct dm_target;
  14 struct dm_table;
  15 struct dm_dev;
  16 struct mapped_device;
  17
  18 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  19
  20 union map_info {
  21         void *ptr;
  22         unsigned long long ll;
  23 };
  24
  25 /*
  26  * In the constructor the target parameter will already have the
  27  * table, type, begin and len fields filled in.
  28  */
  29 typedef int (*dm_ctr_fn) (struct dm_target *target,
  30                           unsigned int argc, char **argv);
  31
  32 /*
  33  * The destructor doesn't need to free the dm_target, just
  34  * anything hidden ti->private.
  35  */
  36 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  37
  38 /*
  39  * The map function must return:
  40  * < 0: error
  41  * = 0: The target will handle the io by resubmitting it later
  42  * > 0: simple remap complete
  43  */
  44 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
  45                           union map_info *map_context);
  46
  47 /*
  48  * Returns:
  49  * < 0 : error (currently ignored)
  50  * 0   : ended successfully
  51  * 1   : for some reason the io has still not completed (eg,
  52  *       multipath target might want to requeue a failed io).
  53  */
  54 typedef int (*dm_endio_fn) (struct dm_target *ti,
  55                             struct bio *bio, int error,
  56                             union map_info *map_context);
  57
  58 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  59 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  60 typedef void (*dm_resume_fn) (struct dm_target *ti);
  61
  62 typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  63                              char *result, unsigned int maxlen);
  64
  65 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  66
  67 void dm_error(const char *message);
  68
  69 /*
  70  * Constructors should call these functions to ensure destination devices
  71  * are opened/closed correctly.
  72  * FIXME: too many arguments.
  73  */
  74 int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
  75                   sector_t len, int mode, struct dm_dev **result);
  76 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
  77
  78 /*
  79  * Information about a target type
  80  */
  81 struct target_type {
  82         const char *name;
  83         struct module *module;
  84         unsigned version[3];
  85         dm_ctr_fn ctr;
  86         dm_dtr_fn dtr;
  87         dm_map_fn map;
  88         dm_endio_fn end_io;
  89         dm_presuspend_fn presuspend;
  90         dm_postsuspend_fn postsuspend;
  91         dm_resume_fn resume;
  92         dm_status_fn status;
  93         dm_message_fn message;
  94 };
  95
  96 struct io_restrictions {
  97         unsigned int            max_sectors;
  98         unsigned short          max_phys_segments;
  99         unsigned short          max_hw_segments;
 100         unsigned short          hardsect_size;
 101         unsigned int            max_segment_size;
 102         unsigned long           seg_boundary_mask;
 103         unsigned char           no_cluster; /* inverted so that 0 is default */
 104 };
 105
 106 struct dm_target {
 107         struct dm_table *table;
 108         struct target_type *type;
 109
 110         /* target limits */
 111         sector_t begin;
 112         sector_t len;
 113
 114         /* FIXME: turn this into a mask, and merge with io_restrictions */
 115         /* Always a power of 2 */
 116         sector_t split_io;
 117
 118         /*
 119          * These are automatically filled in by
 120          * dm_table_get_device.
 121          */
 122         struct io_restrictions limits;
 123
 124         /* target specific data */
 125         void *private;
 126
 127         /* Used to provide an error string from the ctr */
 128         char *error;
 129 };
 130
 131 int dm_register_target(struct target_type *t);
 132 int dm_unregister_target(struct target_type *t);
 133
 134
 135 /*-----------------------------------------------------------------
 136  * Functions for creating and manipulating mapped devices.
 137  * Drop the reference with dm_put when you finish with the object.
 138  *---------------------------------------------------------------*/
 139
 140 /*
 141  * DM_ANY_MINOR chooses the next available minor number.
 142  */
 143 #define DM_ANY_MINOR (-1)
 144 int dm_create(int minor, struct mapped_device **md);
 145
 146 /*
 147  * Reference counting for md.
 148  */
 149 struct mapped_device *dm_get_md(dev_t dev);
 150 void dm_get(struct mapped_device *md);
 151 void dm_put(struct mapped_device *md);
 152
 153 /*
 154  * An arbitrary pointer may be stored alongside a mapped device.
 155  */
 156 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 157 void *dm_get_mdptr(struct mapped_device *md);
 158
 159 /*
 160  * A device can still be used while suspended, but I/O is deferred.
 161  */
 162 int dm_suspend(struct mapped_device *md, int with_lockfs);
 163 int dm_resume(struct mapped_device *md);
 164
 165 /*
 166  * Event functions.
 167  */
 168 uint32_t dm_get_event_nr(struct mapped_device *md);
 169 int dm_wait_event(struct mapped_device *md, int event_nr);
 170
 171 /*
 172  * Info functions.
 173  */
 174 const char *dm_device_name(struct mapped_device *md);
 175 struct gendisk *dm_disk(struct mapped_device *md);
 176 int dm_suspended(struct mapped_device *md);
 177
 178 /*
 179  * Geometry functions.
 180  */
 181 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 182 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 183
 184
 185 /*-----------------------------------------------------------------
 186  * Functions for manipulating device-mapper tables.
 187  *---------------------------------------------------------------*/
 188
 189 /*
 190  * First create an empty table.
 191  */
 192 int dm_table_create(struct dm_table **result, int mode,
 193                     unsigned num_targets, struct mapped_device *md);
 194
 195 /*
 196  * Then call this once for each target.
 197  */
 198 int dm_table_add_target(struct dm_table *t, const char *type,
 199                         sector_t start, sector_t len, char *params);
 200
 201 /*
 202  * Finally call this to make the table ready for use.
 203  */
 204 int dm_table_complete(struct dm_table *t);
 205
 206 /*
 207  * Table reference counting.
 208  */
 209 struct dm_table *dm_get_table(struct mapped_device *md);
 210 void dm_table_get(struct dm_table *t);
 211 void dm_table_put(struct dm_table *t);
 212
 213 /*
 214  * Queries
 215  */
 216 sector_t dm_table_get_size(struct dm_table *t);
 217 unsigned int dm_table_get_num_targets(struct dm_table *t);
 218 int dm_table_get_mode(struct dm_table *t);
 219 struct mapped_device *dm_table_get_md(struct dm_table *t);
 220
 221 /*
 222  * Trigger an event.
 223  */
 224 void dm_table_event(struct dm_table *t);
 225
 226 /*
 227  * The device must be suspended before calling this method.
 228  */
 229 int dm_swap_table(struct mapped_device *md, struct dm_table *t);
 230
 231 /*
 232  * Prepare a table for a device that will error all I/O.
 233  * To make it active, call dm_suspend(), dm_swap_table() then dm_resume().
 234  */
 235 int dm_create_error_table(struct dm_table **result, struct mapped_device *md);
 236
 237 #endif  /* __KERNEL__ */
 238 #endif  /* _LINUX_DEVICE_MAPPER_H */