include/linux/device-mapper.h

   1 /*
   2  * Copyright (C) 2001 Sistina Software (UK) Limited.
   3  * Copyright (C) 2004-2008 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 #include <linux/bio.h>
  12 #include <linux/blkdev.h>
  13
  14 struct dm_dev;
  15 struct dm_target;
  16 struct dm_table;
  17 struct mapped_device;
  18 struct bio_vec;
  19
  20 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  21
  22 union map_info {
  23         void *ptr;
  24         unsigned long long ll;
  25         unsigned flush_request;
  26 };
  27
  28 /*
  29  * In the constructor the target parameter will already have the
  30  * table, type, begin and len fields filled in.
  31  */
  32 typedef int (*dm_ctr_fn) (struct dm_target *target,
  33                           unsigned int argc, char **argv);
  34
  35 /*
  36  * The destructor doesn't need to free the dm_target, just
  37  * anything hidden ti->private.
  38  */
  39 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  40
  41 /*
  42  * The map function must return:
  43  * < 0: error
  44  * = 0: The target will handle the io by resubmitting it later
  45  * = 1: simple remap complete
  46  * = 2: The target wants to push back the io
  47  */
  48 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
  49                           union map_info *map_context);
  50 typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone,
  51                                   union map_info *map_context);
  52
  53 /*
  54  * Returns:
  55  * < 0 : error (currently ignored)
  56  * 0   : ended successfully
  57  * 1   : for some reason the io has still not completed (eg,
  58  *       multipath target might want to requeue a failed io).
  59  * 2   : The target wants to push back the io
  60  */
  61 typedef int (*dm_endio_fn) (struct dm_target *ti,
  62                             struct bio *bio, int error,
  63                             union map_info *map_context);
  64 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  65                                     struct request *clone, int error,
  66                                     union map_info *map_context);
  67
  68 typedef void (*dm_flush_fn) (struct dm_target *ti);
  69 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  70 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  71 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  72 typedef void (*dm_resume_fn) (struct dm_target *ti);
  73
  74 typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  75                              char *result, unsigned int maxlen);
  76
  77 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  78
  79 typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
  80                             unsigned long arg);
  81
  82 typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
  83                             struct bio_vec *biovec, int max_size);
  84
  85 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
  86                                            struct dm_dev *dev,
  87                                            sector_t start, sector_t len,
  88                                            void *data);
  89
  90 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
  91                                       iterate_devices_callout_fn fn,
  92                                       void *data);
  93
  94 /*
  95  * Returns:
  96  *    0: The target can handle the next I/O immediately.
  97  *    1: The target can't handle the next I/O immediately.
  98  */
  99 typedef int (*dm_busy_fn) (struct dm_target *ti);
 100
 101 void dm_error(const char *message);
 102
 103 /*
 104  * Combine device limits.
 105  */
 106 int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 107                          sector_t start, sector_t len, void *data);
 108
 109 struct dm_dev {
 110         struct block_device *bdev;
 111         fmode_t mode;
 112         char name[16];
 113 };
 114
 115 /*
 116  * Constructors should call these functions to ensure destination devices
 117  * are opened/closed correctly.
 118  * FIXME: too many arguments.
 119  */
 120 int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
 121                   sector_t len, fmode_t mode, struct dm_dev **result);
 122 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 123
 124 /*
 125  * Information about a target type
 126  */
 127
 128 /*
 129  * Target features
 130  */
 131
 132 struct target_type {
 133         uint64_t features;
 134         const char *name;
 135         struct module *module;
 136         unsigned version[3];
 137         dm_ctr_fn ctr;
 138         dm_dtr_fn dtr;
 139         dm_map_fn map;
 140         dm_map_request_fn map_rq;
 141         dm_endio_fn end_io;
 142         dm_request_endio_fn rq_end_io;
 143         dm_flush_fn flush;
 144         dm_presuspend_fn presuspend;
 145         dm_postsuspend_fn postsuspend;
 146         dm_preresume_fn preresume;
 147         dm_resume_fn resume;
 148         dm_status_fn status;
 149         dm_message_fn message;
 150         dm_ioctl_fn ioctl;
 151         dm_merge_fn merge;
 152         dm_busy_fn busy;
 153         dm_iterate_devices_fn iterate_devices;
 154
 155         /* For internal device-mapper use. */
 156         struct list_head list;
 157 };
 158
 159 struct dm_target {
 160         struct dm_table *table;
 161         struct target_type *type;
 162
 163         /* target limits */
 164         sector_t begin;
 165         sector_t len;
 166
 167         /* Always a power of 2 */
 168         sector_t split_io;
 169
 170         /*
 171          * A number of zero-length barrier requests that will be submitted
 172          * to the target for the purpose of flushing cache.
 173          *
 174          * The request number will be placed in union map_info->flush_request.
 175          * It is a responsibility of the target driver to remap these requests
 176          * to the real underlying devices.
 177          */
 178         unsigned num_flush_requests;
 179
 180         /* target specific data */
 181         void *private;
 182
 183         /* Used to provide an error string from the ctr */
 184         char *error;
 185 };
 186
 187 int dm_register_target(struct target_type *t);
 188 void dm_unregister_target(struct target_type *t);
 189
 190 /*-----------------------------------------------------------------
 191  * Functions for creating and manipulating mapped devices.
 192  * Drop the reference with dm_put when you finish with the object.
 193  *---------------------------------------------------------------*/
 194
 195 /*
 196  * DM_ANY_MINOR chooses the next available minor number.
 197  */
 198 #define DM_ANY_MINOR (-1)
 199 int dm_create(int minor, struct mapped_device **md);
 200
 201 /*
 202  * Reference counting for md.
 203  */
 204 struct mapped_device *dm_get_md(dev_t dev);
 205 void dm_get(struct mapped_device *md);
 206 void dm_put(struct mapped_device *md);
 207
 208 /*
 209  * An arbitrary pointer may be stored alongside a mapped device.
 210  */
 211 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 212 void *dm_get_mdptr(struct mapped_device *md);
 213
 214 /*
 215  * A device can still be used while suspended, but I/O is deferred.
 216  */
 217 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 218 int dm_resume(struct mapped_device *md);
 219
 220 /*
 221  * Event functions.
 222  */
 223 uint32_t dm_get_event_nr(struct mapped_device *md);
 224 int dm_wait_event(struct mapped_device *md, int event_nr);
 225 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 226 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 227
 228 /*
 229  * Info functions.
 230  */
 231 const char *dm_device_name(struct mapped_device *md);
 232 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 233 struct gendisk *dm_disk(struct mapped_device *md);
 234 int dm_suspended(struct mapped_device *md);
 235 int dm_noflush_suspending(struct dm_target *ti);
 236 union map_info *dm_get_mapinfo(struct bio *bio);
 237 union map_info *dm_get_rq_mapinfo(struct request *rq);
 238
 239 /*
 240  * Geometry functions.
 241  */
 242 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 243 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 244
 245
 246 /*-----------------------------------------------------------------
 247  * Functions for manipulating device-mapper tables.
 248  *---------------------------------------------------------------*/
 249
 250 /*
 251  * First create an empty table.
 252  */
 253 int dm_table_create(struct dm_table **result, fmode_t mode,
 254                     unsigned num_targets, struct mapped_device *md);
 255
 256 /*
 257  * Then call this once for each target.
 258  */
 259 int dm_table_add_target(struct dm_table *t, const char *type,
 260                         sector_t start, sector_t len, char *params);
 261
 262 /*
 263  * Finally call this to make the table ready for use.
 264  */
 265 int dm_table_complete(struct dm_table *t);
 266
 267 /*
 268  * Unplug all devices in a table.
 269  */
 270 void dm_table_unplug_all(struct dm_table *t);
 271
 272 /*
 273  * Table reference counting.
 274  */
 275 struct dm_table *dm_get_table(struct mapped_device *md);
 276 void dm_table_get(struct dm_table *t);
 277 void dm_table_put(struct dm_table *t);
 278
 279 /*
 280  * Queries
 281  */
 282 sector_t dm_table_get_size(struct dm_table *t);
 283 unsigned int dm_table_get_num_targets(struct dm_table *t);
 284 fmode_t dm_table_get_mode(struct dm_table *t);
 285 struct mapped_device *dm_table_get_md(struct dm_table *t);
 286
 287 /*
 288  * Trigger an event.
 289  */
 290 void dm_table_event(struct dm_table *t);
 291
 292 /*
 293  * The device must be suspended before calling this method.
 294  */
 295 int dm_swap_table(struct mapped_device *md, struct dm_table *t);
 296
 297 /*
 298  * A wrapper around vmalloc.
 299  */
 300 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 301
 302 /*-----------------------------------------------------------------
 303  * Macros.
 304  *---------------------------------------------------------------*/
 305 #define DM_NAME "device-mapper"
 306
 307 #define DMCRIT(f, arg...) \
 308         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 309
 310 #define DMERR(f, arg...) \
 311         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 312 #define DMERR_LIMIT(f, arg...) \
 313         do { \
 314                 if (printk_ratelimit()) \
 315                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 316                                f "\n", ## arg); \
 317         } while (0)
 318
 319 #define DMWARN(f, arg...) \
 320         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 321 #define DMWARN_LIMIT(f, arg...) \
 322         do { \
 323                 if (printk_ratelimit()) \
 324                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 325                                f "\n", ## arg); \
 326         } while (0)
 327
 328 #define DMINFO(f, arg...) \
 329         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 330 #define DMINFO_LIMIT(f, arg...) \
 331         do { \
 332                 if (printk_ratelimit()) \
 333                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 334                                "\n", ## arg); \
 335         } while (0)
 336
 337 #ifdef CONFIG_DM_DEBUG
 338 #  define DMDEBUG(f, arg...) \
 339         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 340 #  define DMDEBUG_LIMIT(f, arg...) \
 341         do { \
 342                 if (printk_ratelimit()) \
 343                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 344                                "\n", ## arg); \
 345         } while (0)
 346 #else
 347 #  define DMDEBUG(f, arg...) do {} while (0)
 348 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 349 #endif
 350
 351 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 352                           0 : scnprintf(result + sz, maxlen - sz, x))
 353
 354 #define SECTOR_SHIFT 9
 355
 356 /*
 357  * Definitions of return values from target end_io function.
 358  */
 359 #define DM_ENDIO_INCOMPLETE     1
 360 #define DM_ENDIO_REQUEUE        2
 361
 362 /*
 363  * Definitions of return values from target map function.
 364  */
 365 #define DM_MAPIO_SUBMITTED      0
 366 #define DM_MAPIO_REMAPPED       1
 367 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 368
 369 /*
 370  * Ceiling(n / sz)
 371  */
 372 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 373
 374 #define dm_sector_div_up(n, sz) ( \
 375 { \
 376         sector_t _r = ((n) + (sz) - 1); \
 377         sector_div(_r, (sz)); \
 378         _r; \
 379 } \
 380 )
 381
 382 /*
 383  * ceiling(n / size) * size
 384  */
 385 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 386
 387 #define dm_array_too_big(fixed, obj, num) \
 388         ((num) > (UINT_MAX - (fixed)) / (obj))
 389
 390 static inline sector_t to_sector(unsigned long n)
 391 {
 392         return (n >> SECTOR_SHIFT);
 393 }
 394
 395 static inline unsigned long to_bytes(sector_t n)
 396 {
 397         return (n << SECTOR_SHIFT);
 398 }
 399
 400 /*-----------------------------------------------------------------
 401  * Helper for block layer and dm core operations
 402  *---------------------------------------------------------------*/
 403 void dm_dispatch_request(struct request *rq);
 404 void dm_requeue_unmapped_request(struct request *rq);
 405 void dm_kill_unmapped_request(struct request *rq, int error);
 406 int dm_underlying_device_busy(struct request_queue *q);
 407
 408 #endif  /* _LINUX_DEVICE_MAPPER_H */