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 dev_t dm_get_dev_t(const char *path);
 128
 129 /*
 130  * Constructors should call these functions to ensure destination devices
 131  * are opened/closed correctly.
 132  */
 133 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 134                   struct dm_dev **result);
 135 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 136
 137 /*
 138  * Information about a target type
 139  */
 140
 141 struct target_type {
 142         uint64_t features;
 143         const char *name;
 144         struct module *module;
 145         unsigned version[3];
 146         dm_ctr_fn ctr;
 147         dm_dtr_fn dtr;
 148         dm_map_fn map;
 149         dm_map_request_fn map_rq;
 150         dm_clone_and_map_request_fn clone_and_map_rq;
 151         dm_release_clone_request_fn release_clone_rq;
 152         dm_endio_fn end_io;
 153         dm_request_endio_fn rq_end_io;
 154         dm_presuspend_fn presuspend;
 155         dm_presuspend_undo_fn presuspend_undo;
 156         dm_postsuspend_fn postsuspend;
 157         dm_preresume_fn preresume;
 158         dm_resume_fn resume;
 159         dm_status_fn status;
 160         dm_message_fn message;
 161         dm_prepare_ioctl_fn prepare_ioctl;
 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  * Indicates that a target may replace any target; even immutable targets.
 196  * .map, .map_rq, .clone_and_map_rq and .release_clone_rq are all defined.
 197  */
 198 #define DM_TARGET_WILDCARD              0x00000008
 199 #define dm_target_is_wildcard(type)     ((type)->features & DM_TARGET_WILDCARD)
 200
 201 /*
 202  * Some targets need to be sent the same WRITE bio severals times so
 203  * that they can send copies of it to different devices.  This function
 204  * examines any supplied bio and returns the number of copies of it the
 205  * target requires.
 206  */
 207 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
 208
 209 struct dm_target {
 210         struct dm_table *table;
 211         struct target_type *type;
 212
 213         /* target limits */
 214         sector_t begin;
 215         sector_t len;
 216
 217         /* If non-zero, maximum size of I/O submitted to a target. */
 218         uint32_t max_io_len;
 219
 220         /*
 221          * A number of zero-length barrier bios that will be submitted
 222          * to the target for the purpose of flushing cache.
 223          *
 224          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 225          * It is a responsibility of the target driver to remap these bios
 226          * to the real underlying devices.
 227          */
 228         unsigned num_flush_bios;
 229
 230         /*
 231          * The number of discard bios that will be submitted to the target.
 232          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 233          */
 234         unsigned num_discard_bios;
 235
 236         /*
 237          * The number of WRITE SAME bios that will be submitted to the target.
 238          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 239          */
 240         unsigned num_write_same_bios;
 241
 242         /*
 243          * The minimum number of extra bytes allocated in each io for the
 244          * target to use.
 245          */
 246         unsigned per_io_data_size;
 247
 248         /*
 249          * If defined, this function is called to find out how many
 250          * duplicate bios should be sent to the target when writing
 251          * data.
 252          */
 253         dm_num_write_bios_fn num_write_bios;
 254
 255         /* target specific data */
 256         void *private;
 257
 258         /* Used to provide an error string from the ctr */
 259         char *error;
 260
 261         /*
 262          * Set if this target needs to receive flushes regardless of
 263          * whether or not its underlying devices have support.
 264          */
 265         bool flush_supported:1;
 266
 267         /*
 268          * Set if this target needs to receive discards regardless of
 269          * whether or not its underlying devices have support.
 270          */
 271         bool discards_supported:1;
 272
 273         /*
 274          * Set if the target required discard bios to be split
 275          * on max_io_len boundary.
 276          */
 277         bool split_discard_bios:1;
 278
 279         /*
 280          * Set if this target does not return zeroes on discarded blocks.
 281          */
 282         bool discard_zeroes_data_unsupported:1;
 283 };
 284
 285 /* Each target can link one of these into the table */
 286 struct dm_target_callbacks {
 287         struct list_head list;
 288         int (*congested_fn) (struct dm_target_callbacks *, int);
 289 };
 290
 291 /*
 292  * For bio-based dm.
 293  * One of these is allocated for each bio.
 294  * This structure shouldn't be touched directly by target drivers.
 295  * It is here so that we can inline dm_per_bio_data and
 296  * dm_bio_from_per_bio_data
 297  */
 298 struct dm_target_io {
 299         struct dm_io *io;
 300         struct dm_target *ti;
 301         unsigned target_bio_nr;
 302         unsigned *len_ptr;
 303         struct bio clone;
 304 };
 305
 306 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
 307 {
 308         return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
 309 }
 310
 311 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
 312 {
 313         return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
 314 }
 315
 316 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
 317 {
 318         return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
 319 }
 320
 321 int dm_register_target(struct target_type *t);
 322 void dm_unregister_target(struct target_type *t);
 323
 324 /*
 325  * Target argument parsing.
 326  */
 327 struct dm_arg_set {
 328         unsigned argc;
 329         char **argv;
 330 };
 331
 332 /*
 333  * The minimum and maximum value of a numeric argument, together with
 334  * the error message to use if the number is found to be outside that range.
 335  */
 336 struct dm_arg {
 337         unsigned min;
 338         unsigned max;
 339         char *error;
 340 };
 341
 342 /*
 343  * Validate the next argument, either returning it as *value or, if invalid,
 344  * returning -EINVAL and setting *error.
 345  */
 346 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 347                 unsigned *value, char **error);
 348
 349 /*
 350  * Process the next argument as the start of a group containing between
 351  * arg->min and arg->max further arguments. Either return the size as
 352  * *num_args or, if invalid, return -EINVAL and set *error.
 353  */
 354 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 355                       unsigned *num_args, char **error);
 356
 357 /*
 358  * Return the current argument and shift to the next.
 359  */
 360 const char *dm_shift_arg(struct dm_arg_set *as);
 361
 362 /*
 363  * Move through num_args arguments.
 364  */
 365 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 366
 367 /*-----------------------------------------------------------------
 368  * Functions for creating and manipulating mapped devices.
 369  * Drop the reference with dm_put when you finish with the object.
 370  *---------------------------------------------------------------*/
 371
 372 /*
 373  * DM_ANY_MINOR chooses the next available minor number.
 374  */
 375 #define DM_ANY_MINOR (-1)
 376 int dm_create(int minor, struct mapped_device **md);
 377
 378 /*
 379  * Reference counting for md.
 380  */
 381 struct mapped_device *dm_get_md(dev_t dev);
 382 void dm_get(struct mapped_device *md);
 383 int dm_hold(struct mapped_device *md);
 384 void dm_put(struct mapped_device *md);
 385
 386 /*
 387  * An arbitrary pointer may be stored alongside a mapped device.
 388  */
 389 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 390 void *dm_get_mdptr(struct mapped_device *md);
 391
 392 /*
 393  * A device can still be used while suspended, but I/O is deferred.
 394  */
 395 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 396 int dm_resume(struct mapped_device *md);
 397
 398 /*
 399  * Event functions.
 400  */
 401 uint32_t dm_get_event_nr(struct mapped_device *md);
 402 int dm_wait_event(struct mapped_device *md, int event_nr);
 403 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 404 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 405
 406 /*
 407  * Info functions.
 408  */
 409 const char *dm_device_name(struct mapped_device *md);
 410 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 411 struct gendisk *dm_disk(struct mapped_device *md);
 412 int dm_suspended(struct dm_target *ti);
 413 int dm_noflush_suspending(struct dm_target *ti);
 414 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
 415 union map_info *dm_get_rq_mapinfo(struct request *rq);
 416
 417 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
 418
 419 /*
 420  * Geometry functions.
 421  */
 422 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 423 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 424
 425 /*-----------------------------------------------------------------
 426  * Functions for manipulating device-mapper tables.
 427  *---------------------------------------------------------------*/
 428
 429 /*
 430  * First create an empty table.
 431  */
 432 int dm_table_create(struct dm_table **result, fmode_t mode,
 433                     unsigned num_targets, struct mapped_device *md);
 434
 435 /*
 436  * Then call this once for each target.
 437  */
 438 int dm_table_add_target(struct dm_table *t, const char *type,
 439                         sector_t start, sector_t len, char *params);
 440
 441 /*
 442  * Target_ctr should call this if it needs to add any callbacks.
 443  */
 444 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 445
 446 /*
 447  * Finally call this to make the table ready for use.
 448  */
 449 int dm_table_complete(struct dm_table *t);
 450
 451 /*
 452  * Target may require that it is never sent I/O larger than len.
 453  */
 454 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 455
 456 /*
 457  * Table reference counting.
 458  */
 459 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
 460 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
 461 void dm_sync_table(struct mapped_device *md);
 462
 463 /*
 464  * Queries
 465  */
 466 sector_t dm_table_get_size(struct dm_table *t);
 467 unsigned int dm_table_get_num_targets(struct dm_table *t);
 468 fmode_t dm_table_get_mode(struct dm_table *t);
 469 struct mapped_device *dm_table_get_md(struct dm_table *t);
 470
 471 /*
 472  * Trigger an event.
 473  */
 474 void dm_table_event(struct dm_table *t);
 475
 476 /*
 477  * Run the queue for request-based targets.
 478  */
 479 void dm_table_run_md_queue_async(struct dm_table *t);
 480
 481 /*
 482  * The device must be suspended before calling this method.
 483  * Returns the previous table, which the caller must destroy.
 484  */
 485 struct dm_table *dm_swap_table(struct mapped_device *md,
 486                                struct dm_table *t);
 487
 488 /*
 489  * A wrapper around vmalloc.
 490  */
 491 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 492
 493 /*-----------------------------------------------------------------
 494  * Macros.
 495  *---------------------------------------------------------------*/
 496 #define DM_NAME "device-mapper"
 497
 498 #ifdef CONFIG_PRINTK
 499 extern struct ratelimit_state dm_ratelimit_state;
 500
 501 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 502 #else
 503 #define dm_ratelimit()  0
 504 #endif
 505
 506 #define DMCRIT(f, arg...) \
 507         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 508
 509 #define DMERR(f, arg...) \
 510         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 511 #define DMERR_LIMIT(f, arg...) \
 512         do { \
 513                 if (dm_ratelimit())     \
 514                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 515                                f "\n", ## arg); \
 516         } while (0)
 517
 518 #define DMWARN(f, arg...) \
 519         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 520 #define DMWARN_LIMIT(f, arg...) \
 521         do { \
 522                 if (dm_ratelimit())     \
 523                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 524                                f "\n", ## arg); \
 525         } while (0)
 526
 527 #define DMINFO(f, arg...) \
 528         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 529 #define DMINFO_LIMIT(f, arg...) \
 530         do { \
 531                 if (dm_ratelimit())     \
 532                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 533                                "\n", ## arg); \
 534         } while (0)
 535
 536 #ifdef CONFIG_DM_DEBUG
 537 #  define DMDEBUG(f, arg...) \
 538         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 539 #  define DMDEBUG_LIMIT(f, arg...) \
 540         do { \
 541                 if (dm_ratelimit())     \
 542                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 543                                "\n", ## arg); \
 544         } while (0)
 545 #else
 546 #  define DMDEBUG(f, arg...) do {} while (0)
 547 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 548 #endif
 549
 550 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 551                           0 : scnprintf(result + sz, maxlen - sz, x))
 552
 553 #define SECTOR_SHIFT 9
 554
 555 /*
 556  * Definitions of return values from target end_io function.
 557  */
 558 #define DM_ENDIO_INCOMPLETE     1
 559 #define DM_ENDIO_REQUEUE        2
 560
 561 /*
 562  * Definitions of return values from target map function.
 563  */
 564 #define DM_MAPIO_SUBMITTED      0
 565 #define DM_MAPIO_REMAPPED       1
 566 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 567
 568 #define dm_sector_div64(x, y)( \
 569 { \
 570         u64 _res; \
 571         (x) = div64_u64_rem(x, y, &_res); \
 572         _res; \
 573 } \
 574 )
 575
 576 /*
 577  * Ceiling(n / sz)
 578  */
 579 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 580
 581 #define dm_sector_div_up(n, sz) ( \
 582 { \
 583         sector_t _r = ((n) + (sz) - 1); \
 584         sector_div(_r, (sz)); \
 585         _r; \
 586 } \
 587 )
 588
 589 /*
 590  * ceiling(n / size) * size
 591  */
 592 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 593
 594 #define dm_array_too_big(fixed, obj, num) \
 595         ((num) > (UINT_MAX - (fixed)) / (obj))
 596
 597 /*
 598  * Sector offset taken relative to the start of the target instead of
 599  * relative to the start of the device.
 600  */
 601 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 602
 603 static inline sector_t to_sector(unsigned long n)
 604 {
 605         return (n >> SECTOR_SHIFT);
 606 }
 607
 608 static inline unsigned long to_bytes(sector_t n)
 609 {
 610         return (n << SECTOR_SHIFT);
 611 }
 612
 613 #endif  /* _LINUX_DEVICE_MAPPER_H */