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         unsigned long long ll;
  27 };
  28
  29 /*
  30  * In the constructor the target parameter will already have the
  31  * table, type, begin and len fields filled in.
  32  */
  33 typedef int (*dm_ctr_fn) (struct dm_target *target,
  34                           unsigned int argc, char **argv);
  35
  36 /*
  37  * The destructor doesn't need to free the dm_target, just
  38  * anything hidden ti->private.
  39  */
  40 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  41
  42 /*
  43  * The map function must return:
  44  * < 0: error
  45  * = 0: The target will handle the io by resubmitting it later
  46  * = 1: simple remap complete
  47  * = 2: The target wants to push back the io
  48  */
  49 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio);
  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 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  64                                     struct request *clone, int error,
  65                                     union map_info *map_context);
  66
  67 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  68 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  69 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  70 typedef void (*dm_resume_fn) (struct dm_target *ti);
  71
  72 typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  73                               unsigned status_flags, char *result, unsigned maxlen);
  74
  75 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  76
  77 typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
  78                             unsigned long arg);
  79
  80 typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
  81                             struct bio_vec *biovec, int max_size);
  82
  83 /*
  84  * These iteration functions are typically used to check (and combine)
  85  * properties of underlying devices.
  86  * E.g. Does at least one underlying device support flush?
  87  *      Does any underlying device not support WRITE_SAME?
  88  *
  89  * The callout function is called once for each contiguous section of
  90  * an underlying device.  State can be maintained in *data.
  91  * Return non-zero to stop iterating through any further devices.
  92  */
  93 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
  94                                            struct dm_dev *dev,
  95                                            sector_t start, sector_t len,
  96                                            void *data);
  97
  98 /*
  99  * This function must iterate through each section of device used by the
 100  * target until it encounters a non-zero return code, which it then returns.
 101  * Returns zero if no callout returned non-zero.
 102  */
 103 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
 104                                       iterate_devices_callout_fn fn,
 105                                       void *data);
 106
 107 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
 108                                 struct queue_limits *limits);
 109
 110 /*
 111  * Returns:
 112  *    0: The target can handle the next I/O immediately.
 113  *    1: The target can't handle the next I/O immediately.
 114  */
 115 typedef int (*dm_busy_fn) (struct dm_target *ti);
 116
 117 void dm_error(const char *message);
 118
 119 /*
 120  * Combine device limits.
 121  */
 122 int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 123                          sector_t start, sector_t len, void *data);
 124
 125 struct dm_dev {
 126         struct block_device *bdev;
 127         fmode_t mode;
 128         char name[16];
 129 };
 130
 131 /*
 132  * Constructors should call these functions to ensure destination devices
 133  * are opened/closed correctly.
 134  */
 135 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 136                                                  struct dm_dev **result);
 137 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 138
 139 /*
 140  * Information about a target type
 141  */
 142
 143 struct target_type {
 144         uint64_t features;
 145         const char *name;
 146         struct module *module;
 147         unsigned version[3];
 148         dm_ctr_fn ctr;
 149         dm_dtr_fn dtr;
 150         dm_map_fn map;
 151         dm_map_request_fn map_rq;
 152         dm_endio_fn end_io;
 153         dm_request_endio_fn rq_end_io;
 154         dm_presuspend_fn presuspend;
 155         dm_postsuspend_fn postsuspend;
 156         dm_preresume_fn preresume;
 157         dm_resume_fn resume;
 158         dm_status_fn status;
 159         dm_message_fn message;
 160         dm_ioctl_fn ioctl;
 161         dm_merge_fn merge;
 162         dm_busy_fn busy;
 163         dm_iterate_devices_fn iterate_devices;
 164         dm_io_hints_fn io_hints;
 165
 166         /* For internal device-mapper use. */
 167         struct list_head list;
 168 };
 169
 170 /*
 171  * Target features
 172  */
 173
 174 /*
 175  * Any table that contains an instance of this target must have only one.
 176  */
 177 #define DM_TARGET_SINGLETON             0x00000001
 178 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
 179
 180 /*
 181  * Indicates that a target does not support read-only devices.
 182  */
 183 #define DM_TARGET_ALWAYS_WRITEABLE      0x00000002
 184 #define dm_target_always_writeable(type) \
 185                 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
 186
 187 /*
 188  * Any device that contains a table with an instance of this target may never
 189  * have tables containing any different target type.
 190  */
 191 #define DM_TARGET_IMMUTABLE             0x00000004
 192 #define dm_target_is_immutable(type)    ((type)->features & DM_TARGET_IMMUTABLE)
 193
 194 /*
 195  * Some targets need to be sent the same WRITE bio severals times so
 196  * that they can send copies of it to different devices.  This function
 197  * examines any supplied bio and returns the number of copies of it the
 198  * target requires.
 199  */
 200 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
 201
 202 struct dm_target {
 203         struct dm_table *table;
 204         struct target_type *type;
 205
 206         /* target limits */
 207         sector_t begin;
 208         sector_t len;
 209
 210         /* If non-zero, maximum size of I/O submitted to a target. */
 211         uint32_t max_io_len;
 212
 213         /*
 214          * A number of zero-length barrier bios that will be submitted
 215          * to the target for the purpose of flushing cache.
 216          *
 217          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 218          * It is a responsibility of the target driver to remap these bios
 219          * to the real underlying devices.
 220          */
 221         unsigned num_flush_bios;
 222
 223         /*
 224          * The number of discard bios that will be submitted to the target.
 225          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 226          */
 227         unsigned num_discard_bios;
 228
 229         /*
 230          * The number of WRITE SAME bios that will be submitted to the target.
 231          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 232          */
 233         unsigned num_write_same_bios;
 234
 235         /*
 236          * The minimum number of extra bytes allocated in each bio for the
 237          * target to use.  dm_per_bio_data returns the data location.
 238          */
 239         unsigned per_bio_data_size;
 240
 241         /*
 242          * If defined, this function is called to find out how many
 243          * duplicate bios should be sent to the target when writing
 244          * data.
 245          */
 246         dm_num_write_bios_fn num_write_bios;
 247
 248         /* target specific data */
 249         void *private;
 250
 251         /* Used to provide an error string from the ctr */
 252         char *error;
 253
 254         /*
 255          * Set if this target needs to receive flushes regardless of
 256          * whether or not its underlying devices have support.
 257          */
 258         bool flush_supported:1;
 259
 260         /*
 261          * Set if this target needs to receive discards regardless of
 262          * whether or not its underlying devices have support.
 263          */
 264         bool discards_supported:1;
 265
 266         /*
 267          * Set if the target required discard bios to be split
 268          * on max_io_len boundary.
 269          */
 270         bool split_discard_bios:1;
 271
 272         /*
 273          * Set if this target does not return zeroes on discarded blocks.
 274          */
 275         bool discard_zeroes_data_unsupported:1;
 276 };
 277
 278 /* Each target can link one of these into the table */
 279 struct dm_target_callbacks {
 280         struct list_head list;
 281         int (*congested_fn) (struct dm_target_callbacks *, int);
 282 };
 283
 284 /*
 285  * For bio-based dm.
 286  * One of these is allocated for each bio.
 287  * This structure shouldn't be touched directly by target drivers.
 288  * It is here so that we can inline dm_per_bio_data and
 289  * dm_bio_from_per_bio_data
 290  */
 291 struct dm_target_io {
 292         struct dm_io *io;
 293         struct dm_target *ti;
 294         union map_info info;
 295         unsigned target_bio_nr;
 296         struct bio clone;
 297 };
 298
 299 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
 300 {
 301         return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
 302 }
 303
 304 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
 305 {
 306         return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
 307 }
 308
 309 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
 310 {
 311         return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
 312 }
 313
 314 int dm_register_target(struct target_type *t);
 315 void dm_unregister_target(struct target_type *t);
 316
 317 /*
 318  * Target argument parsing.
 319  */
 320 struct dm_arg_set {
 321         unsigned argc;
 322         char **argv;
 323 };
 324
 325 /*
 326  * The minimum and maximum value of a numeric argument, together with
 327  * the error message to use if the number is found to be outside that range.
 328  */
 329 struct dm_arg {
 330         unsigned min;
 331         unsigned max;
 332         char *error;
 333 };
 334
 335 /*
 336  * Validate the next argument, either returning it as *value or, if invalid,
 337  * returning -EINVAL and setting *error.
 338  */
 339 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 340                 unsigned *value, char **error);
 341
 342 /*
 343  * Process the next argument as the start of a group containing between
 344  * arg->min and arg->max further arguments. Either return the size as
 345  * *num_args or, if invalid, return -EINVAL and set *error.
 346  */
 347 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 348                       unsigned *num_args, char **error);
 349
 350 /*
 351  * Return the current argument and shift to the next.
 352  */
 353 const char *dm_shift_arg(struct dm_arg_set *as);
 354
 355 /*
 356  * Move through num_args arguments.
 357  */
 358 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 359
 360 /*-----------------------------------------------------------------
 361  * Functions for creating and manipulating mapped devices.
 362  * Drop the reference with dm_put when you finish with the object.
 363  *---------------------------------------------------------------*/
 364
 365 /*
 366  * DM_ANY_MINOR chooses the next available minor number.
 367  */
 368 #define DM_ANY_MINOR (-1)
 369 int dm_create(int minor, struct mapped_device **md);
 370
 371 /*
 372  * Reference counting for md.
 373  */
 374 struct mapped_device *dm_get_md(dev_t dev);
 375 void dm_get(struct mapped_device *md);
 376 void dm_put(struct mapped_device *md);
 377
 378 /*
 379  * An arbitrary pointer may be stored alongside a mapped device.
 380  */
 381 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 382 void *dm_get_mdptr(struct mapped_device *md);
 383
 384 /*
 385  * A device can still be used while suspended, but I/O is deferred.
 386  */
 387 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 388 int dm_resume(struct mapped_device *md);
 389
 390 /*
 391  * Event functions.
 392  */
 393 uint32_t dm_get_event_nr(struct mapped_device *md);
 394 int dm_wait_event(struct mapped_device *md, int event_nr);
 395 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 396 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 397
 398 /*
 399  * Info functions.
 400  */
 401 const char *dm_device_name(struct mapped_device *md);
 402 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 403 struct gendisk *dm_disk(struct mapped_device *md);
 404 int dm_suspended(struct dm_target *ti);
 405 int dm_noflush_suspending(struct dm_target *ti);
 406 union map_info *dm_get_mapinfo(struct bio *bio);
 407 union map_info *dm_get_rq_mapinfo(struct request *rq);
 408
 409 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
 410
 411 /*
 412  * Geometry functions.
 413  */
 414 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 415 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 416
 417 /*-----------------------------------------------------------------
 418  * Functions for manipulating device-mapper tables.
 419  *---------------------------------------------------------------*/
 420
 421 /*
 422  * First create an empty table.
 423  */
 424 int dm_table_create(struct dm_table **result, fmode_t mode,
 425                     unsigned num_targets, struct mapped_device *md);
 426
 427 /*
 428  * Then call this once for each target.
 429  */
 430 int dm_table_add_target(struct dm_table *t, const char *type,
 431                         sector_t start, sector_t len, char *params);
 432
 433 /*
 434  * Target_ctr should call this if it needs to add any callbacks.
 435  */
 436 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 437
 438 /*
 439  * Finally call this to make the table ready for use.
 440  */
 441 int dm_table_complete(struct dm_table *t);
 442
 443 /*
 444  * Target may require that it is never sent I/O larger than len.
 445  */
 446 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 447
 448 /*
 449  * Table reference counting.
 450  */
 451 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
 452 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
 453 void dm_sync_table(struct mapped_device *md);
 454
 455 /*
 456  * Queries
 457  */
 458 sector_t dm_table_get_size(struct dm_table *t);
 459 unsigned int dm_table_get_num_targets(struct dm_table *t);
 460 fmode_t dm_table_get_mode(struct dm_table *t);
 461 struct mapped_device *dm_table_get_md(struct dm_table *t);
 462
 463 /*
 464  * Trigger an event.
 465  */
 466 void dm_table_event(struct dm_table *t);
 467
 468 /*
 469  * The device must be suspended before calling this method.
 470  * Returns the previous table, which the caller must destroy.
 471  */
 472 struct dm_table *dm_swap_table(struct mapped_device *md,
 473                                struct dm_table *t);
 474
 475 /*
 476  * A wrapper around vmalloc.
 477  */
 478 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 479
 480 /*-----------------------------------------------------------------
 481  * Macros.
 482  *---------------------------------------------------------------*/
 483 #define DM_NAME "device-mapper"
 484
 485 #ifdef CONFIG_PRINTK
 486 extern struct ratelimit_state dm_ratelimit_state;
 487
 488 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 489 #else
 490 #define dm_ratelimit()  0
 491 #endif
 492
 493 #define DMCRIT(f, arg...) \
 494         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 495
 496 #define DMERR(f, arg...) \
 497         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 498 #define DMERR_LIMIT(f, arg...) \
 499         do { \
 500                 if (dm_ratelimit())     \
 501                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 502                                f "\n", ## arg); \
 503         } while (0)
 504
 505 #define DMWARN(f, arg...) \
 506         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 507 #define DMWARN_LIMIT(f, arg...) \
 508         do { \
 509                 if (dm_ratelimit())     \
 510                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 511                                f "\n", ## arg); \
 512         } while (0)
 513
 514 #define DMINFO(f, arg...) \
 515         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 516 #define DMINFO_LIMIT(f, arg...) \
 517         do { \
 518                 if (dm_ratelimit())     \
 519                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 520                                "\n", ## arg); \
 521         } while (0)
 522
 523 #ifdef CONFIG_DM_DEBUG
 524 #  define DMDEBUG(f, arg...) \
 525         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 526 #  define DMDEBUG_LIMIT(f, arg...) \
 527         do { \
 528                 if (dm_ratelimit())     \
 529                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 530                                "\n", ## arg); \
 531         } while (0)
 532 #else
 533 #  define DMDEBUG(f, arg...) do {} while (0)
 534 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 535 #endif
 536
 537 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 538                           0 : scnprintf(result + sz, maxlen - sz, x))
 539
 540 #define SECTOR_SHIFT 9
 541
 542 /*
 543  * Definitions of return values from target end_io function.
 544  */
 545 #define DM_ENDIO_INCOMPLETE     1
 546 #define DM_ENDIO_REQUEUE        2
 547
 548 /*
 549  * Definitions of return values from target map function.
 550  */
 551 #define DM_MAPIO_SUBMITTED      0
 552 #define DM_MAPIO_REMAPPED       1
 553 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 554
 555 #define dm_sector_div64(x, y)( \
 556 { \
 557         u64 _res; \
 558         (x) = div64_u64_rem(x, y, &_res); \
 559         _res; \
 560 } \
 561 )
 562
 563 /*
 564  * Ceiling(n / sz)
 565  */
 566 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 567
 568 #define dm_sector_div_up(n, sz) ( \
 569 { \
 570         sector_t _r = ((n) + (sz) - 1); \
 571         sector_div(_r, (sz)); \
 572         _r; \
 573 } \
 574 )
 575
 576 /*
 577  * ceiling(n / size) * size
 578  */
 579 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 580
 581 #define dm_array_too_big(fixed, obj, num) \
 582         ((num) > (UINT_MAX - (fixed)) / (obj))
 583
 584 /*
 585  * Sector offset taken relative to the start of the target instead of
 586  * relative to the start of the device.
 587  */
 588 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 589
 590 static inline sector_t to_sector(unsigned long n)
 591 {
 592         return (n >> SECTOR_SHIFT);
 593 }
 594
 595 static inline unsigned long to_bytes(sector_t n)
 596 {
 597         return (n << SECTOR_SHIFT);
 598 }
 599
 600 /*-----------------------------------------------------------------
 601  * Helper for block layer and dm core operations
 602  *---------------------------------------------------------------*/
 603 void dm_dispatch_request(struct request *rq);
 604 void dm_requeue_unmapped_request(struct request *rq);
 605 void dm_kill_unmapped_request(struct request *rq, int error);
 606 int dm_underlying_device_busy(struct request_queue *q);
 607
 608 #endif  /* _LINUX_DEVICE_MAPPER_H */