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 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
  95                                 struct queue_limits *limits);
  96
  97 /*
  98  * Returns:
  99  *    0: The target can handle the next I/O immediately.
 100  *    1: The target can't handle the next I/O immediately.
 101  */
 102 typedef int (*dm_busy_fn) (struct dm_target *ti);
 103
 104 void dm_error(const char *message);
 105
 106 /*
 107  * Combine device limits.
 108  */
 109 int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 110                          sector_t start, sector_t len, void *data);
 111
 112 struct dm_dev {
 113         struct block_device *bdev;
 114         fmode_t mode;
 115         char name[16];
 116 };
 117
 118 /*
 119  * Constructors should call these functions to ensure destination devices
 120  * are opened/closed correctly.
 121  * FIXME: too many arguments.
 122  */
 123 int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
 124                   sector_t len, fmode_t mode, struct dm_dev **result);
 125 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 126
 127 /*
 128  * Information about a target type
 129  */
 130
 131 /*
 132  * Target features
 133  */
 134
 135 struct target_type {
 136         uint64_t features;
 137         const char *name;
 138         struct module *module;
 139         unsigned version[3];
 140         dm_ctr_fn ctr;
 141         dm_dtr_fn dtr;
 142         dm_map_fn map;
 143         dm_map_request_fn map_rq;
 144         dm_endio_fn end_io;
 145         dm_request_endio_fn rq_end_io;
 146         dm_flush_fn flush;
 147         dm_presuspend_fn presuspend;
 148         dm_postsuspend_fn postsuspend;
 149         dm_preresume_fn preresume;
 150         dm_resume_fn resume;
 151         dm_status_fn status;
 152         dm_message_fn message;
 153         dm_ioctl_fn ioctl;
 154         dm_merge_fn merge;
 155         dm_busy_fn busy;
 156         dm_iterate_devices_fn iterate_devices;
 157         dm_io_hints_fn io_hints;
 158
 159         /* For internal device-mapper use. */
 160         struct list_head list;
 161 };
 162
 163 struct dm_target {
 164         struct dm_table *table;
 165         struct target_type *type;
 166
 167         /* target limits */
 168         sector_t begin;
 169         sector_t len;
 170
 171         /* Always a power of 2 */
 172         sector_t split_io;
 173
 174         /*
 175          * A number of zero-length barrier requests that will be submitted
 176          * to the target for the purpose of flushing cache.
 177          *
 178          * The request number will be placed in union map_info->flush_request.
 179          * It is a responsibility of the target driver to remap these requests
 180          * to the real underlying devices.
 181          */
 182         unsigned num_flush_requests;
 183
 184         /* target specific data */
 185         void *private;
 186
 187         /* Used to provide an error string from the ctr */
 188         char *error;
 189 };
 190
 191 int dm_register_target(struct target_type *t);
 192 void dm_unregister_target(struct target_type *t);
 193
 194 /*-----------------------------------------------------------------
 195  * Functions for creating and manipulating mapped devices.
 196  * Drop the reference with dm_put when you finish with the object.
 197  *---------------------------------------------------------------*/
 198
 199 /*
 200  * DM_ANY_MINOR chooses the next available minor number.
 201  */
 202 #define DM_ANY_MINOR (-1)
 203 int dm_create(int minor, struct mapped_device **md);
 204
 205 /*
 206  * Reference counting for md.
 207  */
 208 struct mapped_device *dm_get_md(dev_t dev);
 209 void dm_get(struct mapped_device *md);
 210 void dm_put(struct mapped_device *md);
 211
 212 /*
 213  * An arbitrary pointer may be stored alongside a mapped device.
 214  */
 215 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 216 void *dm_get_mdptr(struct mapped_device *md);
 217
 218 /*
 219  * A device can still be used while suspended, but I/O is deferred.
 220  */
 221 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 222 int dm_resume(struct mapped_device *md);
 223
 224 /*
 225  * Event functions.
 226  */
 227 uint32_t dm_get_event_nr(struct mapped_device *md);
 228 int dm_wait_event(struct mapped_device *md, int event_nr);
 229 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 230 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 231
 232 /*
 233  * Info functions.
 234  */
 235 const char *dm_device_name(struct mapped_device *md);
 236 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 237 struct gendisk *dm_disk(struct mapped_device *md);
 238 int dm_suspended(struct dm_target *ti);
 239 int dm_noflush_suspending(struct dm_target *ti);
 240 union map_info *dm_get_mapinfo(struct bio *bio);
 241 union map_info *dm_get_rq_mapinfo(struct request *rq);
 242
 243 /*
 244  * Geometry functions.
 245  */
 246 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 247 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 248
 249
 250 /*-----------------------------------------------------------------
 251  * Functions for manipulating device-mapper tables.
 252  *---------------------------------------------------------------*/
 253
 254 /*
 255  * First create an empty table.
 256  */
 257 int dm_table_create(struct dm_table **result, fmode_t mode,
 258                     unsigned num_targets, struct mapped_device *md);
 259
 260 /*
 261  * Then call this once for each target.
 262  */
 263 int dm_table_add_target(struct dm_table *t, const char *type,
 264                         sector_t start, sector_t len, char *params);
 265
 266 /*
 267  * Finally call this to make the table ready for use.
 268  */
 269 int dm_table_complete(struct dm_table *t);
 270
 271 /*
 272  * Unplug all devices in a table.
 273  */
 274 void dm_table_unplug_all(struct dm_table *t);
 275
 276 /*
 277  * Table reference counting.
 278  */
 279 struct dm_table *dm_get_live_table(struct mapped_device *md);
 280 void dm_table_get(struct dm_table *t);
 281 void dm_table_put(struct dm_table *t);
 282
 283 /*
 284  * Queries
 285  */
 286 sector_t dm_table_get_size(struct dm_table *t);
 287 unsigned int dm_table_get_num_targets(struct dm_table *t);
 288 fmode_t dm_table_get_mode(struct dm_table *t);
 289 struct mapped_device *dm_table_get_md(struct dm_table *t);
 290
 291 /*
 292  * Trigger an event.
 293  */
 294 void dm_table_event(struct dm_table *t);
 295
 296 /*
 297  * The device must be suspended before calling this method.
 298  * Returns the previous table, which the caller must destroy.
 299  */
 300 struct dm_table *dm_swap_table(struct mapped_device *md,
 301                                struct dm_table *t);
 302
 303 /*
 304  * A wrapper around vmalloc.
 305  */
 306 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 307
 308 /*-----------------------------------------------------------------
 309  * Macros.
 310  *---------------------------------------------------------------*/
 311 #define DM_NAME "device-mapper"
 312
 313 #define DMCRIT(f, arg...) \
 314         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 315
 316 #define DMERR(f, arg...) \
 317         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 318 #define DMERR_LIMIT(f, arg...) \
 319         do { \
 320                 if (printk_ratelimit()) \
 321                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 322                                f "\n", ## arg); \
 323         } while (0)
 324
 325 #define DMWARN(f, arg...) \
 326         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 327 #define DMWARN_LIMIT(f, arg...) \
 328         do { \
 329                 if (printk_ratelimit()) \
 330                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 331                                f "\n", ## arg); \
 332         } while (0)
 333
 334 #define DMINFO(f, arg...) \
 335         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 336 #define DMINFO_LIMIT(f, arg...) \
 337         do { \
 338                 if (printk_ratelimit()) \
 339                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 340                                "\n", ## arg); \
 341         } while (0)
 342
 343 #ifdef CONFIG_DM_DEBUG
 344 #  define DMDEBUG(f, arg...) \
 345         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 346 #  define DMDEBUG_LIMIT(f, arg...) \
 347         do { \
 348                 if (printk_ratelimit()) \
 349                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 350                                "\n", ## arg); \
 351         } while (0)
 352 #else
 353 #  define DMDEBUG(f, arg...) do {} while (0)
 354 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 355 #endif
 356
 357 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 358                           0 : scnprintf(result + sz, maxlen - sz, x))
 359
 360 #define SECTOR_SHIFT 9
 361
 362 /*
 363  * Definitions of return values from target end_io function.
 364  */
 365 #define DM_ENDIO_INCOMPLETE     1
 366 #define DM_ENDIO_REQUEUE        2
 367
 368 /*
 369  * Definitions of return values from target map function.
 370  */
 371 #define DM_MAPIO_SUBMITTED      0
 372 #define DM_MAPIO_REMAPPED       1
 373 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 374
 375 /*
 376  * Ceiling(n / sz)
 377  */
 378 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 379
 380 #define dm_sector_div_up(n, sz) ( \
 381 { \
 382         sector_t _r = ((n) + (sz) - 1); \
 383         sector_div(_r, (sz)); \
 384         _r; \
 385 } \
 386 )
 387
 388 /*
 389  * ceiling(n / size) * size
 390  */
 391 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 392
 393 #define dm_array_too_big(fixed, obj, num) \
 394         ((num) > (UINT_MAX - (fixed)) / (obj))
 395
 396 static inline sector_t to_sector(unsigned long n)
 397 {
 398         return (n >> SECTOR_SHIFT);
 399 }
 400
 401 static inline unsigned long to_bytes(sector_t n)
 402 {
 403         return (n << SECTOR_SHIFT);
 404 }
 405
 406 /*-----------------------------------------------------------------
 407  * Helper for block layer and dm core operations
 408  *---------------------------------------------------------------*/
 409 void dm_dispatch_request(struct request *rq);
 410 void dm_requeue_unmapped_request(struct request *rq);
 411 void dm_kill_unmapped_request(struct request *rq, int error);
 412 int dm_underlying_device_busy(struct request_queue *q);
 413
 414 #endif  /* _LINUX_DEVICE_MAPPER_H */