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 typedef int (*dm_clone_and_map_request_fn) (struct dm_target *ti,
  52                                             struct request *rq,
  53                                             union map_info *map_context,
  54                                             struct request **clone);
  55 typedef void (*dm_release_clone_request_fn) (struct request *clone);
  56
  57 /*
  58  * Returns:
  59  * < 0 : error (currently ignored)
  60  * 0   : ended successfully
  61  * 1   : for some reason the io has still not completed (eg,
  62  *       multipath target might want to requeue a failed io).
  63  * 2   : The target wants to push back the io
  64  */
  65 typedef int (*dm_endio_fn) (struct dm_target *ti,
  66                             struct bio *bio, int error);
  67 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  68                                     struct request *clone, int error,
  69                                     union map_info *map_context);
  70
  71 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  72 typedef void (*dm_presuspend_undo_fn) (struct dm_target *ti);
  73 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  74 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  75 typedef void (*dm_resume_fn) (struct dm_target *ti);
  76
  77 typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  78                               unsigned status_flags, char *result, unsigned maxlen);
  79
  80 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  81
  82 typedef int (*dm_prepare_ioctl_fn) (struct dm_target *ti,
  83                             struct block_device **bdev, fmode_t *mode);
  84
  85 /*
  86  * These iteration functions are typically used to check (and combine)
  87  * properties of underlying devices.
  88  * E.g. Does at least one underlying device support flush?
  89  *      Does any underlying device not support WRITE_SAME?
  90  *
  91  * The callout function is called once for each contiguous section of
  92  * an underlying device.  State can be maintained in *data.
  93  * Return non-zero to stop iterating through any further devices.
  94  */
  95 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
  96                                            struct dm_dev *dev,
  97                                            sector_t start, sector_t len,
  98                                            void *data);
  99
 100 /*
 101  * This function must iterate through each section of device used by the
 102  * target until it encounters a non-zero return code, which it then returns.
 103  * Returns zero if no callout returned non-zero.
 104  */
 105 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
 106                                       iterate_devices_callout_fn fn,
 107                                       void *data);
 108
 109 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
 110                                 struct queue_limits *limits);
 111
 112 /*
 113  * Returns:
 114  *    0: The target can handle the next I/O immediately.
 115  *    1: The target can't handle the next I/O immediately.
 116  */
 117 typedef int (*dm_busy_fn) (struct dm_target *ti);
 118
 119 void dm_error(const char *message);
 120
 121 struct dm_dev {
 122         struct block_device *bdev;
 123         fmode_t mode;
 124         char name[16];
 125 };
 126
 127 /*
 128  * Constructors should call these functions to ensure destination devices
 129  * are opened/closed correctly.
 130  */
 131 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 132                   struct dm_dev **result);
 133 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 134
 135 /*
 136  * Information about a target type
 137  */
 138
 139 struct target_type {
 140         uint64_t features;
 141         const char *name;
 142         struct module *module;
 143         unsigned version[3];
 144         dm_ctr_fn ctr;
 145         dm_dtr_fn dtr;
 146         dm_map_fn map;
 147         dm_map_request_fn map_rq;
 148         dm_clone_and_map_request_fn clone_and_map_rq;
 149         dm_release_clone_request_fn release_clone_rq;
 150         dm_endio_fn end_io;
 151         dm_request_endio_fn rq_end_io;
 152         dm_presuspend_fn presuspend;
 153         dm_presuspend_undo_fn presuspend_undo;
 154         dm_postsuspend_fn postsuspend;
 155         dm_preresume_fn preresume;
 156         dm_resume_fn resume;
 157         dm_status_fn status;
 158         dm_message_fn message;
 159         dm_prepare_ioctl_fn prepare_ioctl;
 160         dm_busy_fn busy;
 161         dm_iterate_devices_fn iterate_devices;
 162         dm_io_hints_fn io_hints;
 163
 164         /* For internal device-mapper use. */
 165         struct list_head list;
 166 };
 167
 168 /*
 169  * Target features
 170  */
 171
 172 /*
 173  * Any table that contains an instance of this target must have only one.
 174  */
 175 #define DM_TARGET_SINGLETON             0x00000001
 176 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
 177
 178 /*
 179  * Indicates that a target does not support read-only devices.
 180  */
 181 #define DM_TARGET_ALWAYS_WRITEABLE      0x00000002
 182 #define dm_target_always_writeable(type) \
 183                 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
 184
 185 /*
 186  * Any device that contains a table with an instance of this target may never
 187  * have tables containing any different target type.
 188  */
 189 #define DM_TARGET_IMMUTABLE             0x00000004
 190 #define dm_target_is_immutable(type)    ((type)->features & DM_TARGET_IMMUTABLE)
 191
 192 /*
 193  * Some targets need to be sent the same WRITE bio severals times so
 194  * that they can send copies of it to different devices.  This function
 195  * examines any supplied bio and returns the number of copies of it the
 196  * target requires.
 197  */
 198 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
 199
 200 struct dm_target {
 201         struct dm_table *table;
 202         struct target_type *type;
 203
 204         /* target limits */
 205         sector_t begin;
 206         sector_t len;
 207
 208         /* If non-zero, maximum size of I/O submitted to a target. */
 209         uint32_t max_io_len;
 210
 211         /*
 212          * A number of zero-length barrier bios that will be submitted
 213          * to the target for the purpose of flushing cache.
 214          *
 215          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 216          * It is a responsibility of the target driver to remap these bios
 217          * to the real underlying devices.
 218          */
 219         unsigned num_flush_bios;
 220
 221         /*
 222          * The number of discard bios that will be submitted to the target.
 223          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 224          */
 225         unsigned num_discard_bios;
 226
 227         /*
 228          * The number of WRITE SAME bios that will be submitted to the target.
 229          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 230          */
 231         unsigned num_write_same_bios;
 232
 233         /*
 234          * The minimum number of extra bytes allocated in each bio for the
 235          * target to use.  dm_per_bio_data returns the data location.
 236          */
 237         unsigned per_bio_data_size;
 238
 239         /*
 240          * If defined, this function is called to find out how many
 241          * duplicate bios should be sent to the target when writing
 242          * data.
 243          */
 244         dm_num_write_bios_fn num_write_bios;
 245
 246         /* target specific data */
 247         void *private;
 248
 249         /* Used to provide an error string from the ctr */
 250         char *error;
 251
 252         /*
 253          * Set if this target needs to receive flushes regardless of
 254          * whether or not its underlying devices have support.
 255          */
 256         bool flush_supported:1;
 257
 258         /*
 259          * Set if this target needs to receive discards regardless of
 260          * whether or not its underlying devices have support.
 261          */
 262         bool discards_supported:1;
 263
 264         /*
 265          * Set if the target required discard bios to be split
 266          * on max_io_len boundary.
 267          */
 268         bool split_discard_bios:1;
 269
 270         /*
 271          * Set if this target does not return zeroes on discarded blocks.
 272          */
 273         bool discard_zeroes_data_unsupported:1;
 274 };
 275
 276 /* Each target can link one of these into the table */
 277 struct dm_target_callbacks {
 278         struct list_head list;
 279         int (*congested_fn) (struct dm_target_callbacks *, int);
 280 };
 281
 282 /*
 283  * For bio-based dm.
 284  * One of these is allocated for each bio.
 285  * This structure shouldn't be touched directly by target drivers.
 286  * It is here so that we can inline dm_per_bio_data and
 287  * dm_bio_from_per_bio_data
 288  */
 289 struct dm_target_io {
 290         struct dm_io *io;
 291         struct dm_target *ti;
 292         unsigned target_bio_nr;
 293         unsigned *len_ptr;
 294         struct bio clone;
 295 };
 296
 297 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
 298 {
 299         return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
 300 }
 301
 302 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
 303 {
 304         return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
 305 }
 306
 307 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
 308 {
 309         return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
 310 }
 311
 312 int dm_register_target(struct target_type *t);
 313 void dm_unregister_target(struct target_type *t);
 314
 315 /*
 316  * Target argument parsing.
 317  */
 318 struct dm_arg_set {
 319         unsigned argc;
 320         char **argv;
 321 };
 322
 323 /*
 324  * The minimum and maximum value of a numeric argument, together with
 325  * the error message to use if the number is found to be outside that range.
 326  */
 327 struct dm_arg {
 328         unsigned min;
 329         unsigned max;
 330         char *error;
 331 };
 332
 333 /*
 334  * Validate the next argument, either returning it as *value or, if invalid,
 335  * returning -EINVAL and setting *error.
 336  */
 337 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 338                 unsigned *value, char **error);
 339
 340 /*
 341  * Process the next argument as the start of a group containing between
 342  * arg->min and arg->max further arguments. Either return the size as
 343  * *num_args or, if invalid, return -EINVAL and set *error.
 344  */
 345 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 346                       unsigned *num_args, char **error);
 347
 348 /*
 349  * Return the current argument and shift to the next.
 350  */
 351 const char *dm_shift_arg(struct dm_arg_set *as);
 352
 353 /*
 354  * Move through num_args arguments.
 355  */
 356 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 357
 358 /*-----------------------------------------------------------------
 359  * Functions for creating and manipulating mapped devices.
 360  * Drop the reference with dm_put when you finish with the object.
 361  *---------------------------------------------------------------*/
 362
 363 /*
 364  * DM_ANY_MINOR chooses the next available minor number.
 365  */
 366 #define DM_ANY_MINOR (-1)
 367 int dm_create(int minor, struct mapped_device **md);
 368
 369 /*
 370  * Reference counting for md.
 371  */
 372 struct mapped_device *dm_get_md(dev_t dev);
 373 void dm_get(struct mapped_device *md);
 374 int dm_hold(struct mapped_device *md);
 375 void dm_put(struct mapped_device *md);
 376
 377 /*
 378  * An arbitrary pointer may be stored alongside a mapped device.
 379  */
 380 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 381 void *dm_get_mdptr(struct mapped_device *md);
 382
 383 /*
 384  * A device can still be used while suspended, but I/O is deferred.
 385  */
 386 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 387 int dm_resume(struct mapped_device *md);
 388
 389 /*
 390  * Event functions.
 391  */
 392 uint32_t dm_get_event_nr(struct mapped_device *md);
 393 int dm_wait_event(struct mapped_device *md, int event_nr);
 394 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 395 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 396
 397 /*
 398  * Info functions.
 399  */
 400 const char *dm_device_name(struct mapped_device *md);
 401 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 402 struct gendisk *dm_disk(struct mapped_device *md);
 403 int dm_suspended(struct dm_target *ti);
 404 int dm_noflush_suspending(struct dm_target *ti);
 405 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
 406 union map_info *dm_get_rq_mapinfo(struct request *rq);
 407
 408 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
 409
 410 /*
 411  * Geometry functions.
 412  */
 413 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 414 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 415
 416 /*-----------------------------------------------------------------
 417  * Functions for manipulating device-mapper tables.
 418  *---------------------------------------------------------------*/
 419
 420 /*
 421  * First create an empty table.
 422  */
 423 int dm_table_create(struct dm_table **result, fmode_t mode,
 424                     unsigned num_targets, struct mapped_device *md);
 425
 426 /*
 427  * Then call this once for each target.
 428  */
 429 int dm_table_add_target(struct dm_table *t, const char *type,
 430                         sector_t start, sector_t len, char *params);
 431
 432 /*
 433  * Target_ctr should call this if it needs to add any callbacks.
 434  */
 435 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 436
 437 /*
 438  * Finally call this to make the table ready for use.
 439  */
 440 int dm_table_complete(struct dm_table *t);
 441
 442 /*
 443  * Target may require that it is never sent I/O larger than len.
 444  */
 445 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 446
 447 /*
 448  * Table reference counting.
 449  */
 450 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
 451 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
 452 void dm_sync_table(struct mapped_device *md);
 453
 454 /*
 455  * Queries
 456  */
 457 sector_t dm_table_get_size(struct dm_table *t);
 458 unsigned int dm_table_get_num_targets(struct dm_table *t);
 459 fmode_t dm_table_get_mode(struct dm_table *t);
 460 struct mapped_device *dm_table_get_md(struct dm_table *t);
 461
 462 /*
 463  * Trigger an event.
 464  */
 465 void dm_table_event(struct dm_table *t);
 466
 467 /*
 468  * Run the queue for request-based targets.
 469  */
 470 void dm_table_run_md_queue_async(struct dm_table *t);
 471
 472 /*
 473  * The device must be suspended before calling this method.
 474  * Returns the previous table, which the caller must destroy.
 475  */
 476 struct dm_table *dm_swap_table(struct mapped_device *md,
 477                                struct dm_table *t);
 478
 479 /*
 480  * A wrapper around vmalloc.
 481  */
 482 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 483
 484 /*-----------------------------------------------------------------
 485  * Macros.
 486  *---------------------------------------------------------------*/
 487 #define DM_NAME "device-mapper"
 488
 489 #ifdef CONFIG_PRINTK
 490 extern struct ratelimit_state dm_ratelimit_state;
 491
 492 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 493 #else
 494 #define dm_ratelimit()  0
 495 #endif
 496
 497 #define DMCRIT(f, arg...) \
 498         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 499
 500 #define DMERR(f, arg...) \
 501         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 502 #define DMERR_LIMIT(f, arg...) \
 503         do { \
 504                 if (dm_ratelimit())     \
 505                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 506                                f "\n", ## arg); \
 507         } while (0)
 508
 509 #define DMWARN(f, arg...) \
 510         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 511 #define DMWARN_LIMIT(f, arg...) \
 512         do { \
 513                 if (dm_ratelimit())     \
 514                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 515                                f "\n", ## arg); \
 516         } while (0)
 517
 518 #define DMINFO(f, arg...) \
 519         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 520 #define DMINFO_LIMIT(f, arg...) \
 521         do { \
 522                 if (dm_ratelimit())     \
 523                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 524                                "\n", ## arg); \
 525         } while (0)
 526
 527 #ifdef CONFIG_DM_DEBUG
 528 #  define DMDEBUG(f, arg...) \
 529         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 530 #  define DMDEBUG_LIMIT(f, arg...) \
 531         do { \
 532                 if (dm_ratelimit())     \
 533                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 534                                "\n", ## arg); \
 535         } while (0)
 536 #else
 537 #  define DMDEBUG(f, arg...) do {} while (0)
 538 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 539 #endif
 540
 541 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 542                           0 : scnprintf(result + sz, maxlen - sz, x))
 543
 544 #define SECTOR_SHIFT 9
 545
 546 /*
 547  * Definitions of return values from target end_io function.
 548  */
 549 #define DM_ENDIO_INCOMPLETE     1
 550 #define DM_ENDIO_REQUEUE        2
 551
 552 /*
 553  * Definitions of return values from target map function.
 554  */
 555 #define DM_MAPIO_SUBMITTED      0
 556 #define DM_MAPIO_REMAPPED       1
 557 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 558
 559 #define dm_sector_div64(x, y)( \
 560 { \
 561         u64 _res; \
 562         (x) = div64_u64_rem(x, y, &_res); \
 563         _res; \
 564 } \
 565 )
 566
 567 /*
 568  * Ceiling(n / sz)
 569  */
 570 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 571
 572 #define dm_sector_div_up(n, sz) ( \
 573 { \
 574         sector_t _r = ((n) + (sz) - 1); \
 575         sector_div(_r, (sz)); \
 576         _r; \
 577 } \
 578 )
 579
 580 /*
 581  * ceiling(n / size) * size
 582  */
 583 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 584
 585 #define dm_array_too_big(fixed, obj, num) \
 586         ((num) > (UINT_MAX - (fixed)) / (obj))
 587
 588 /*
 589  * Sector offset taken relative to the start of the target instead of
 590  * relative to the start of the device.
 591  */
 592 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 593
 594 static inline sector_t to_sector(unsigned long n)
 595 {
 596         return (n >> SECTOR_SHIFT);
 597 }
 598
 599 static inline unsigned long to_bytes(sector_t n)
 600 {
 601         return (n << SECTOR_SHIFT);
 602 }
 603
 604 #endif  /* _LINUX_DEVICE_MAPPER_H */