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 target_request_nr;
  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  */
 122 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 123                                                  struct dm_dev **result);
 124 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 125
 126 /*
 127  * Information about a target type
 128  */
 129
 130 /*
 131  * Target features
 132  */
 133
 134 struct target_type {
 135         uint64_t features;
 136         const char *name;
 137         struct module *module;
 138         unsigned version[3];
 139         dm_ctr_fn ctr;
 140         dm_dtr_fn dtr;
 141         dm_map_fn map;
 142         dm_map_request_fn map_rq;
 143         dm_endio_fn end_io;
 144         dm_request_endio_fn rq_end_io;
 145         dm_flush_fn flush;
 146         dm_presuspend_fn presuspend;
 147         dm_postsuspend_fn postsuspend;
 148         dm_preresume_fn preresume;
 149         dm_resume_fn resume;
 150         dm_status_fn status;
 151         dm_message_fn message;
 152         dm_ioctl_fn ioctl;
 153         dm_merge_fn merge;
 154         dm_busy_fn busy;
 155         dm_iterate_devices_fn iterate_devices;
 156         dm_io_hints_fn io_hints;
 157
 158         /* For internal device-mapper use. */
 159         struct list_head list;
 160 };
 161
 162 struct dm_target {
 163         struct dm_table *table;
 164         struct target_type *type;
 165
 166         /* target limits */
 167         sector_t begin;
 168         sector_t len;
 169
 170         /* Always a power of 2 */
 171         sector_t split_io;
 172
 173         /*
 174          * A number of zero-length barrier requests that will be submitted
 175          * to the target for the purpose of flushing cache.
 176          *
 177          * The request number will be placed in union map_info->target_request_nr.
 178          * It is a responsibility of the target driver to remap these requests
 179          * to the real underlying devices.
 180          */
 181         unsigned num_flush_requests;
 182
 183         /*
 184          * The number of discard requests that will be submitted to the
 185          * target.  map_info->request_nr is used just like num_flush_requests.
 186          */
 187         unsigned num_discard_requests;
 188
 189         /* target specific data */
 190         void *private;
 191
 192         /* Used to provide an error string from the ctr */
 193         char *error;
 194
 195         /*
 196          * Set if this target needs to receive discards regardless of
 197          * whether or not its underlying devices have support.
 198          */
 199         unsigned discards_supported:1;
 200
 201         /*
 202          * Set if this target does not return zeroes on discarded blocks.
 203          */
 204         unsigned discard_zeroes_data_unsupported:1;
 205 };
 206
 207 /* Each target can link one of these into the table */
 208 struct dm_target_callbacks {
 209         struct list_head list;
 210         int (*congested_fn) (struct dm_target_callbacks *, int);
 211 };
 212
 213 int dm_register_target(struct target_type *t);
 214 void dm_unregister_target(struct target_type *t);
 215
 216 /*
 217  * Target argument parsing.
 218  */
 219 struct dm_arg_set {
 220         unsigned argc;
 221         char **argv;
 222 };
 223
 224 /*
 225  * The minimum and maximum value of a numeric argument, together with
 226  * the error message to use if the number is found to be outside that range.
 227  */
 228 struct dm_arg {
 229         unsigned min;
 230         unsigned max;
 231         char *error;
 232 };
 233
 234 /*
 235  * Validate the next argument, either returning it as *value or, if invalid,
 236  * returning -EINVAL and setting *error.
 237  */
 238 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 239                 unsigned *value, char **error);
 240
 241 /*
 242  * Process the next argument as the start of a group containing between
 243  * arg->min and arg->max further arguments. Either return the size as
 244  * *num_args or, if invalid, return -EINVAL and set *error.
 245  */
 246 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 247                       unsigned *num_args, char **error);
 248
 249 /*
 250  * Return the current argument and shift to the next.
 251  */
 252 const char *dm_shift_arg(struct dm_arg_set *as);
 253
 254 /*
 255  * Move through num_args arguments.
 256  */
 257 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 258
 259 /*-----------------------------------------------------------------
 260  * Functions for creating and manipulating mapped devices.
 261  * Drop the reference with dm_put when you finish with the object.
 262  *---------------------------------------------------------------*/
 263
 264 /*
 265  * DM_ANY_MINOR chooses the next available minor number.
 266  */
 267 #define DM_ANY_MINOR (-1)
 268 int dm_create(int minor, struct mapped_device **md);
 269
 270 /*
 271  * Reference counting for md.
 272  */
 273 struct mapped_device *dm_get_md(dev_t dev);
 274 void dm_get(struct mapped_device *md);
 275 void dm_put(struct mapped_device *md);
 276
 277 /*
 278  * An arbitrary pointer may be stored alongside a mapped device.
 279  */
 280 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 281 void *dm_get_mdptr(struct mapped_device *md);
 282
 283 /*
 284  * A device can still be used while suspended, but I/O is deferred.
 285  */
 286 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 287 int dm_resume(struct mapped_device *md);
 288
 289 /*
 290  * Event functions.
 291  */
 292 uint32_t dm_get_event_nr(struct mapped_device *md);
 293 int dm_wait_event(struct mapped_device *md, int event_nr);
 294 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 295 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 296
 297 /*
 298  * Info functions.
 299  */
 300 const char *dm_device_name(struct mapped_device *md);
 301 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 302 struct gendisk *dm_disk(struct mapped_device *md);
 303 int dm_suspended(struct dm_target *ti);
 304 int dm_noflush_suspending(struct dm_target *ti);
 305 union map_info *dm_get_mapinfo(struct bio *bio);
 306 union map_info *dm_get_rq_mapinfo(struct request *rq);
 307
 308 /*
 309  * Geometry functions.
 310  */
 311 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 312 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 313
 314
 315 /*-----------------------------------------------------------------
 316  * Functions for manipulating device-mapper tables.
 317  *---------------------------------------------------------------*/
 318
 319 /*
 320  * First create an empty table.
 321  */
 322 int dm_table_create(struct dm_table **result, fmode_t mode,
 323                     unsigned num_targets, struct mapped_device *md);
 324
 325 /*
 326  * Then call this once for each target.
 327  */
 328 int dm_table_add_target(struct dm_table *t, const char *type,
 329                         sector_t start, sector_t len, char *params);
 330
 331 /*
 332  * Target_ctr should call this if it needs to add any callbacks.
 333  */
 334 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 335
 336 /*
 337  * Finally call this to make the table ready for use.
 338  */
 339 int dm_table_complete(struct dm_table *t);
 340
 341 /*
 342  * Table reference counting.
 343  */
 344 struct dm_table *dm_get_live_table(struct mapped_device *md);
 345 void dm_table_get(struct dm_table *t);
 346 void dm_table_put(struct dm_table *t);
 347
 348 /*
 349  * Queries
 350  */
 351 sector_t dm_table_get_size(struct dm_table *t);
 352 unsigned int dm_table_get_num_targets(struct dm_table *t);
 353 fmode_t dm_table_get_mode(struct dm_table *t);
 354 struct mapped_device *dm_table_get_md(struct dm_table *t);
 355
 356 /*
 357  * Trigger an event.
 358  */
 359 void dm_table_event(struct dm_table *t);
 360
 361 /*
 362  * The device must be suspended before calling this method.
 363  * Returns the previous table, which the caller must destroy.
 364  */
 365 struct dm_table *dm_swap_table(struct mapped_device *md,
 366                                struct dm_table *t);
 367
 368 /*
 369  * A wrapper around vmalloc.
 370  */
 371 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 372
 373 /*-----------------------------------------------------------------
 374  * Macros.
 375  *---------------------------------------------------------------*/
 376 #define DM_NAME "device-mapper"
 377
 378 #define DMCRIT(f, arg...) \
 379         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 380
 381 #define DMERR(f, arg...) \
 382         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 383 #define DMERR_LIMIT(f, arg...) \
 384         do { \
 385                 if (printk_ratelimit()) \
 386                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 387                                f "\n", ## arg); \
 388         } while (0)
 389
 390 #define DMWARN(f, arg...) \
 391         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 392 #define DMWARN_LIMIT(f, arg...) \
 393         do { \
 394                 if (printk_ratelimit()) \
 395                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 396                                f "\n", ## arg); \
 397         } while (0)
 398
 399 #define DMINFO(f, arg...) \
 400         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 401 #define DMINFO_LIMIT(f, arg...) \
 402         do { \
 403                 if (printk_ratelimit()) \
 404                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 405                                "\n", ## arg); \
 406         } while (0)
 407
 408 #ifdef CONFIG_DM_DEBUG
 409 #  define DMDEBUG(f, arg...) \
 410         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 411 #  define DMDEBUG_LIMIT(f, arg...) \
 412         do { \
 413                 if (printk_ratelimit()) \
 414                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 415                                "\n", ## arg); \
 416         } while (0)
 417 #else
 418 #  define DMDEBUG(f, arg...) do {} while (0)
 419 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 420 #endif
 421
 422 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 423                           0 : scnprintf(result + sz, maxlen - sz, x))
 424
 425 #define SECTOR_SHIFT 9
 426
 427 /*
 428  * Definitions of return values from target end_io function.
 429  */
 430 #define DM_ENDIO_INCOMPLETE     1
 431 #define DM_ENDIO_REQUEUE        2
 432
 433 /*
 434  * Definitions of return values from target map function.
 435  */
 436 #define DM_MAPIO_SUBMITTED      0
 437 #define DM_MAPIO_REMAPPED       1
 438 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 439
 440 /*
 441  * Ceiling(n / sz)
 442  */
 443 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 444
 445 #define dm_sector_div_up(n, sz) ( \
 446 { \
 447         sector_t _r = ((n) + (sz) - 1); \
 448         sector_div(_r, (sz)); \
 449         _r; \
 450 } \
 451 )
 452
 453 /*
 454  * ceiling(n / size) * size
 455  */
 456 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 457
 458 #define dm_array_too_big(fixed, obj, num) \
 459         ((num) > (UINT_MAX - (fixed)) / (obj))
 460
 461 /*
 462  * Sector offset taken relative to the start of the target instead of
 463  * relative to the start of the device.
 464  */
 465 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 466
 467 static inline sector_t to_sector(unsigned long n)
 468 {
 469         return (n >> SECTOR_SHIFT);
 470 }
 471
 472 static inline unsigned long to_bytes(sector_t n)
 473 {
 474         return (n << SECTOR_SHIFT);
 475 }
 476
 477 /*-----------------------------------------------------------------
 478  * Helper for block layer and dm core operations
 479  *---------------------------------------------------------------*/
 480 void dm_dispatch_request(struct request *rq);
 481 void dm_requeue_unmapped_request(struct request *rq);
 482 void dm_kill_unmapped_request(struct request *rq, int error);
 483 int dm_underlying_device_busy(struct request_queue *q);
 484
 485 #endif  /* _LINUX_DEVICE_MAPPER_H */