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 #include <linux/math64.h>
  14 #include <linux/ratelimit.h>
  15
  16 struct dm_dev;
  17 struct dm_target;
  18 struct dm_table;
  19 struct mapped_device;
  20 struct bio_vec;
  21
  22 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  23
  24 union map_info {
  25         void *ptr;
  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 typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone,
  50                                   union map_info *map_context);
  51
  52 /*
  53  * Returns:
  54  * < 0 : error (currently ignored)
  55  * 0   : ended successfully
  56  * 1   : for some reason the io has still not completed (eg,
  57  *       multipath target might want to requeue a failed io).
  58  * 2   : The target wants to push back the io
  59  */
  60 typedef int (*dm_endio_fn) (struct dm_target *ti,
  61                             struct bio *bio, int error);
  62 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  63                                     struct request *clone, int error,
  64                                     union map_info *map_context);
  65
  66 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  67 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  68 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  69 typedef void (*dm_resume_fn) (struct dm_target *ti);
  70
  71 typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  72                               unsigned status_flags, char *result, unsigned maxlen);
  73
  74 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  75
  76 typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
  77                             unsigned long arg);
  78
  79 typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
  80                             struct bio_vec *biovec, int max_size);
  81
  82 /*
  83  * These iteration functions are typically used to check (and combine)
  84  * properties of underlying devices.
  85  * E.g. Does at least one underlying device support flush?
  86  *      Does any underlying device not support WRITE_SAME?
  87  *
  88  * The callout function is called once for each contiguous section of
  89  * an underlying device.  State can be maintained in *data.
  90  * Return non-zero to stop iterating through any further devices.
  91  */
  92 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
  93                                            struct dm_dev *dev,
  94                                            sector_t start, sector_t len,
  95                                            void *data);
  96
  97 /*
  98  * This function must iterate through each section of device used by the
  99  * target until it encounters a non-zero return code, which it then returns.
 100  * Returns zero if no callout returned non-zero.
 101  */
 102 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
 103                                       iterate_devices_callout_fn fn,
 104                                       void *data);
 105
 106 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
 107                                 struct queue_limits *limits);
 108
 109 /*
 110  * Returns:
 111  *    0: The target can handle the next I/O immediately.
 112  *    1: The target can't handle the next I/O immediately.
 113  */
 114 typedef int (*dm_busy_fn) (struct dm_target *ti);
 115
 116 void dm_error(const char *message);
 117
 118 struct dm_dev {
 119         struct block_device *bdev;
 120         fmode_t mode;
 121         char name[16];
 122 };
 123
 124 /*
 125  * Constructors should call these functions to ensure destination devices
 126  * are opened/closed correctly.
 127  */
 128 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 129                   struct dm_dev **result);
 130 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 131
 132 /*
 133  * Information about a target type
 134  */
 135
 136 struct target_type {
 137         uint64_t features;
 138         const char *name;
 139         struct module *module;
 140         unsigned version[3];
 141         dm_ctr_fn ctr;
 142         dm_dtr_fn dtr;
 143         dm_map_fn map;
 144         dm_map_request_fn map_rq;
 145         dm_endio_fn end_io;
 146         dm_request_endio_fn rq_end_io;
 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 /*
 164  * Target features
 165  */
 166
 167 /*
 168  * Any table that contains an instance of this target must have only one.
 169  */
 170 #define DM_TARGET_SINGLETON             0x00000001
 171 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
 172
 173 /*
 174  * Indicates that a target does not support read-only devices.
 175  */
 176 #define DM_TARGET_ALWAYS_WRITEABLE      0x00000002
 177 #define dm_target_always_writeable(type) \
 178                 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
 179
 180 /*
 181  * Any device that contains a table with an instance of this target may never
 182  * have tables containing any different target type.
 183  */
 184 #define DM_TARGET_IMMUTABLE             0x00000004
 185 #define dm_target_is_immutable(type)    ((type)->features & DM_TARGET_IMMUTABLE)
 186
 187 /*
 188  * Some targets need to be sent the same WRITE bio severals times so
 189  * that they can send copies of it to different devices.  This function
 190  * examines any supplied bio and returns the number of copies of it the
 191  * target requires.
 192  */
 193 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
 194
 195 struct dm_target {
 196         struct dm_table *table;
 197         struct target_type *type;
 198
 199         /* target limits */
 200         sector_t begin;
 201         sector_t len;
 202
 203         /* If non-zero, maximum size of I/O submitted to a target. */
 204         uint32_t max_io_len;
 205
 206         /*
 207          * A number of zero-length barrier bios that will be submitted
 208          * to the target for the purpose of flushing cache.
 209          *
 210          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 211          * It is a responsibility of the target driver to remap these bios
 212          * to the real underlying devices.
 213          */
 214         unsigned num_flush_bios;
 215
 216         /*
 217          * The number of discard bios that will be submitted to the target.
 218          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 219          */
 220         unsigned num_discard_bios;
 221
 222         /*
 223          * The number of WRITE SAME bios that will be submitted to the target.
 224          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 225          */
 226         unsigned num_write_same_bios;
 227
 228         /*
 229          * The minimum number of extra bytes allocated in each bio for the
 230          * target to use.  dm_per_bio_data returns the data location.
 231          */
 232         unsigned per_bio_data_size;
 233
 234         /*
 235          * If defined, this function is called to find out how many
 236          * duplicate bios should be sent to the target when writing
 237          * data.
 238          */
 239         dm_num_write_bios_fn num_write_bios;
 240
 241         /* target specific data */
 242         void *private;
 243
 244         /* Used to provide an error string from the ctr */
 245         char *error;
 246
 247         /*
 248          * Set if this target needs to receive flushes regardless of
 249          * whether or not its underlying devices have support.
 250          */
 251         bool flush_supported:1;
 252
 253         /*
 254          * Set if this target needs to receive discards regardless of
 255          * whether or not its underlying devices have support.
 256          */
 257         bool discards_supported:1;
 258
 259         /*
 260          * Set if the target required discard bios to be split
 261          * on max_io_len boundary.
 262          */
 263         bool split_discard_bios:1;
 264
 265         /*
 266          * Set if this target does not return zeroes on discarded blocks.
 267          */
 268         bool discard_zeroes_data_unsupported:1;
 269 };
 270
 271 /* Each target can link one of these into the table */
 272 struct dm_target_callbacks {
 273         struct list_head list;
 274         int (*congested_fn) (struct dm_target_callbacks *, int);
 275 };
 276
 277 /*
 278  * For bio-based dm.
 279  * One of these is allocated for each bio.
 280  * This structure shouldn't be touched directly by target drivers.
 281  * It is here so that we can inline dm_per_bio_data and
 282  * dm_bio_from_per_bio_data
 283  */
 284 struct dm_target_io {
 285         struct dm_io *io;
 286         struct dm_target *ti;
 287         unsigned target_bio_nr;
 288         unsigned *len_ptr;
 289         struct bio clone;
 290 };
 291
 292 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
 293 {
 294         return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
 295 }
 296
 297 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
 298 {
 299         return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
 300 }
 301
 302 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
 303 {
 304         return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
 305 }
 306
 307 int dm_register_target(struct target_type *t);
 308 void dm_unregister_target(struct target_type *t);
 309
 310 /*
 311  * Target argument parsing.
 312  */
 313 struct dm_arg_set {
 314         unsigned argc;
 315         char **argv;
 316 };
 317
 318 /*
 319  * The minimum and maximum value of a numeric argument, together with
 320  * the error message to use if the number is found to be outside that range.
 321  */
 322 struct dm_arg {
 323         unsigned min;
 324         unsigned max;
 325         char *error;
 326 };
 327
 328 /*
 329  * Validate the next argument, either returning it as *value or, if invalid,
 330  * returning -EINVAL and setting *error.
 331  */
 332 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 333                 unsigned *value, char **error);
 334
 335 /*
 336  * Process the next argument as the start of a group containing between
 337  * arg->min and arg->max further arguments. Either return the size as
 338  * *num_args or, if invalid, return -EINVAL and set *error.
 339  */
 340 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 341                       unsigned *num_args, char **error);
 342
 343 /*
 344  * Return the current argument and shift to the next.
 345  */
 346 const char *dm_shift_arg(struct dm_arg_set *as);
 347
 348 /*
 349  * Move through num_args arguments.
 350  */
 351 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 352
 353 /*-----------------------------------------------------------------
 354  * Functions for creating and manipulating mapped devices.
 355  * Drop the reference with dm_put when you finish with the object.
 356  *---------------------------------------------------------------*/
 357
 358 /*
 359  * DM_ANY_MINOR chooses the next available minor number.
 360  */
 361 #define DM_ANY_MINOR (-1)
 362 int dm_create(int minor, struct mapped_device **md);
 363
 364 /*
 365  * Reference counting for md.
 366  */
 367 struct mapped_device *dm_get_md(dev_t dev);
 368 void dm_get(struct mapped_device *md);
 369 void dm_put(struct mapped_device *md);
 370
 371 /*
 372  * An arbitrary pointer may be stored alongside a mapped device.
 373  */
 374 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 375 void *dm_get_mdptr(struct mapped_device *md);
 376
 377 /*
 378  * A device can still be used while suspended, but I/O is deferred.
 379  */
 380 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 381 int dm_resume(struct mapped_device *md);
 382
 383 /*
 384  * Event functions.
 385  */
 386 uint32_t dm_get_event_nr(struct mapped_device *md);
 387 int dm_wait_event(struct mapped_device *md, int event_nr);
 388 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 389 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 390
 391 /*
 392  * Info functions.
 393  */
 394 const char *dm_device_name(struct mapped_device *md);
 395 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 396 struct gendisk *dm_disk(struct mapped_device *md);
 397 int dm_suspended(struct dm_target *ti);
 398 int dm_noflush_suspending(struct dm_target *ti);
 399 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
 400 union map_info *dm_get_rq_mapinfo(struct request *rq);
 401
 402 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
 403
 404 /*
 405  * Geometry functions.
 406  */
 407 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 408 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 409
 410 /*-----------------------------------------------------------------
 411  * Functions for manipulating device-mapper tables.
 412  *---------------------------------------------------------------*/
 413
 414 /*
 415  * First create an empty table.
 416  */
 417 int dm_table_create(struct dm_table **result, fmode_t mode,
 418                     unsigned num_targets, struct mapped_device *md);
 419
 420 /*
 421  * Then call this once for each target.
 422  */
 423 int dm_table_add_target(struct dm_table *t, const char *type,
 424                         sector_t start, sector_t len, char *params);
 425
 426 /*
 427  * Target_ctr should call this if it needs to add any callbacks.
 428  */
 429 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 430
 431 /*
 432  * Finally call this to make the table ready for use.
 433  */
 434 int dm_table_complete(struct dm_table *t);
 435
 436 /*
 437  * Target may require that it is never sent I/O larger than len.
 438  */
 439 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 440
 441 /*
 442  * Table reference counting.
 443  */
 444 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
 445 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
 446 void dm_sync_table(struct mapped_device *md);
 447
 448 /*
 449  * Queries
 450  */
 451 sector_t dm_table_get_size(struct dm_table *t);
 452 unsigned int dm_table_get_num_targets(struct dm_table *t);
 453 fmode_t dm_table_get_mode(struct dm_table *t);
 454 struct mapped_device *dm_table_get_md(struct dm_table *t);
 455
 456 /*
 457  * Trigger an event.
 458  */
 459 void dm_table_event(struct dm_table *t);
 460
 461 /*
 462  * Run the queue for request-based targets.
 463  */
 464 void dm_table_run_md_queue_async(struct dm_table *t);
 465
 466 /*
 467  * The device must be suspended before calling this method.
 468  * Returns the previous table, which the caller must destroy.
 469  */
 470 struct dm_table *dm_swap_table(struct mapped_device *md,
 471                                struct dm_table *t);
 472
 473 /*
 474  * A wrapper around vmalloc.
 475  */
 476 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 477
 478 /*-----------------------------------------------------------------
 479  * Macros.
 480  *---------------------------------------------------------------*/
 481 #define DM_NAME "device-mapper"
 482
 483 #ifdef CONFIG_PRINTK
 484 extern struct ratelimit_state dm_ratelimit_state;
 485
 486 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 487 #else
 488 #define dm_ratelimit()  0
 489 #endif
 490
 491 #define DMCRIT(f, arg...) \
 492         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 493
 494 #define DMERR(f, arg...) \
 495         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 496 #define DMERR_LIMIT(f, arg...) \
 497         do { \
 498                 if (dm_ratelimit())     \
 499                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 500                                f "\n", ## arg); \
 501         } while (0)
 502
 503 #define DMWARN(f, arg...) \
 504         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 505 #define DMWARN_LIMIT(f, arg...) \
 506         do { \
 507                 if (dm_ratelimit())     \
 508                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 509                                f "\n", ## arg); \
 510         } while (0)
 511
 512 #define DMINFO(f, arg...) \
 513         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 514 #define DMINFO_LIMIT(f, arg...) \
 515         do { \
 516                 if (dm_ratelimit())     \
 517                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 518                                "\n", ## arg); \
 519         } while (0)
 520
 521 #ifdef CONFIG_DM_DEBUG
 522 #  define DMDEBUG(f, arg...) \
 523         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 524 #  define DMDEBUG_LIMIT(f, arg...) \
 525         do { \
 526                 if (dm_ratelimit())     \
 527                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 528                                "\n", ## arg); \
 529         } while (0)
 530 #else
 531 #  define DMDEBUG(f, arg...) do {} while (0)
 532 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 533 #endif
 534
 535 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 536                           0 : scnprintf(result + sz, maxlen - sz, x))
 537
 538 #define SECTOR_SHIFT 9
 539
 540 /*
 541  * Definitions of return values from target end_io function.
 542  */
 543 #define DM_ENDIO_INCOMPLETE     1
 544 #define DM_ENDIO_REQUEUE        2
 545
 546 /*
 547  * Definitions of return values from target map function.
 548  */
 549 #define DM_MAPIO_SUBMITTED      0
 550 #define DM_MAPIO_REMAPPED       1
 551 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 552
 553 #define dm_sector_div64(x, y)( \
 554 { \
 555         u64 _res; \
 556         (x) = div64_u64_rem(x, y, &_res); \
 557         _res; \
 558 } \
 559 )
 560
 561 /*
 562  * Ceiling(n / sz)
 563  */
 564 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 565
 566 #define dm_sector_div_up(n, sz) ( \
 567 { \
 568         sector_t _r = ((n) + (sz) - 1); \
 569         sector_div(_r, (sz)); \
 570         _r; \
 571 } \
 572 )
 573
 574 /*
 575  * ceiling(n / size) * size
 576  */
 577 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 578
 579 #define dm_array_too_big(fixed, obj, num) \
 580         ((num) > (UINT_MAX - (fixed)) / (obj))
 581
 582 /*
 583  * Sector offset taken relative to the start of the target instead of
 584  * relative to the start of the device.
 585  */
 586 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 587
 588 static inline sector_t to_sector(unsigned long n)
 589 {
 590         return (n >> SECTOR_SHIFT);
 591 }
 592
 593 static inline unsigned long to_bytes(sector_t n)
 594 {
 595         return (n << SECTOR_SHIFT);
 596 }
 597
 598 /*-----------------------------------------------------------------
 599  * Helper for block layer and dm core operations
 600  *---------------------------------------------------------------*/
 601 void dm_dispatch_request(struct request *rq);
 602 void dm_requeue_unmapped_request(struct request *rq);
 603 void dm_kill_unmapped_request(struct request *rq, int error);
 604 int dm_underlying_device_busy(struct request_queue *q);
 605
 606 #endif  /* _LINUX_DEVICE_MAPPER_H */