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_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
  83                             unsigned long arg);
  84
  85 typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
  86                             struct bio_vec *biovec, int max_size);
  87
  88 /*
  89  * These iteration functions are typically used to check (and combine)
  90  * properties of underlying devices.
  91  * E.g. Does at least one underlying device support flush?
  92  *      Does any underlying device not support WRITE_SAME?
  93  *
  94  * The callout function is called once for each contiguous section of
  95  * an underlying device.  State can be maintained in *data.
  96  * Return non-zero to stop iterating through any further devices.
  97  */
  98 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
  99                                            struct dm_dev *dev,
 100                                            sector_t start, sector_t len,
 101                                            void *data);
 102
 103 /*
 104  * This function must iterate through each section of device used by the
 105  * target until it encounters a non-zero return code, which it then returns.
 106  * Returns zero if no callout returned non-zero.
 107  */
 108 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
 109                                       iterate_devices_callout_fn fn,
 110                                       void *data);
 111
 112 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
 113                                 struct queue_limits *limits);
 114
 115 /*
 116  * Returns:
 117  *    0: The target can handle the next I/O immediately.
 118  *    1: The target can't handle the next I/O immediately.
 119  */
 120 typedef int (*dm_busy_fn) (struct dm_target *ti);
 121
 122 void dm_error(const char *message);
 123
 124 struct dm_dev {
 125         struct block_device *bdev;
 126         fmode_t mode;
 127         char name[16];
 128 };
 129
 130 /*
 131  * Constructors should call these functions to ensure destination devices
 132  * are opened/closed correctly.
 133  */
 134 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 135                   struct dm_dev **result);
 136 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 137
 138 /*
 139  * Information about a target type
 140  */
 141
 142 struct target_type {
 143         uint64_t features;
 144         const char *name;
 145         struct module *module;
 146         unsigned version[3];
 147         dm_ctr_fn ctr;
 148         dm_dtr_fn dtr;
 149         dm_map_fn map;
 150         dm_map_request_fn map_rq;
 151         dm_clone_and_map_request_fn clone_and_map_rq;
 152         dm_release_clone_request_fn release_clone_rq;
 153         dm_endio_fn end_io;
 154         dm_request_endio_fn rq_end_io;
 155         dm_presuspend_fn presuspend;
 156         dm_presuspend_undo_fn presuspend_undo;
 157         dm_postsuspend_fn postsuspend;
 158         dm_preresume_fn preresume;
 159         dm_resume_fn resume;
 160         dm_status_fn status;
 161         dm_message_fn message;
 162         dm_ioctl_fn ioctl;
 163         dm_merge_fn merge;
 164         dm_busy_fn busy;
 165         dm_iterate_devices_fn iterate_devices;
 166         dm_io_hints_fn io_hints;
 167
 168         /* For internal device-mapper use. */
 169         struct list_head list;
 170 };
 171
 172 /*
 173  * Target features
 174  */
 175
 176 /*
 177  * Any table that contains an instance of this target must have only one.
 178  */
 179 #define DM_TARGET_SINGLETON             0x00000001
 180 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
 181
 182 /*
 183  * Indicates that a target does not support read-only devices.
 184  */
 185 #define DM_TARGET_ALWAYS_WRITEABLE      0x00000002
 186 #define dm_target_always_writeable(type) \
 187                 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
 188
 189 /*
 190  * Any device that contains a table with an instance of this target may never
 191  * have tables containing any different target type.
 192  */
 193 #define DM_TARGET_IMMUTABLE             0x00000004
 194 #define dm_target_is_immutable(type)    ((type)->features & DM_TARGET_IMMUTABLE)
 195
 196 /*
 197  * Some targets need to be sent the same WRITE bio severals times so
 198  * that they can send copies of it to different devices.  This function
 199  * examines any supplied bio and returns the number of copies of it the
 200  * target requires.
 201  */
 202 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
 203
 204 struct dm_target {
 205         struct dm_table *table;
 206         struct target_type *type;
 207
 208         /* target limits */
 209         sector_t begin;
 210         sector_t len;
 211
 212         /* If non-zero, maximum size of I/O submitted to a target. */
 213         uint32_t max_io_len;
 214
 215         /*
 216          * A number of zero-length barrier bios that will be submitted
 217          * to the target for the purpose of flushing cache.
 218          *
 219          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 220          * It is a responsibility of the target driver to remap these bios
 221          * to the real underlying devices.
 222          */
 223         unsigned num_flush_bios;
 224
 225         /*
 226          * The number of discard bios that will be submitted to the target.
 227          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 228          */
 229         unsigned num_discard_bios;
 230
 231         /*
 232          * The number of WRITE SAME bios that will be submitted to the target.
 233          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 234          */
 235         unsigned num_write_same_bios;
 236
 237         /*
 238          * The minimum number of extra bytes allocated in each bio for the
 239          * target to use.  dm_per_bio_data returns the data location.
 240          */
 241         unsigned per_bio_data_size;
 242
 243         /*
 244          * If defined, this function is called to find out how many
 245          * duplicate bios should be sent to the target when writing
 246          * data.
 247          */
 248         dm_num_write_bios_fn num_write_bios;
 249
 250         /* target specific data */
 251         void *private;
 252
 253         /* Used to provide an error string from the ctr */
 254         char *error;
 255
 256         /*
 257          * Set if this target needs to receive flushes regardless of
 258          * whether or not its underlying devices have support.
 259          */
 260         bool flush_supported:1;
 261
 262         /*
 263          * Set if this target needs to receive discards regardless of
 264          * whether or not its underlying devices have support.
 265          */
 266         bool discards_supported:1;
 267
 268         /*
 269          * Set if the target required discard bios to be split
 270          * on max_io_len boundary.
 271          */
 272         bool split_discard_bios:1;
 273
 274         /*
 275          * Set if this target does not return zeroes on discarded blocks.
 276          */
 277         bool discard_zeroes_data_unsupported:1;
 278 };
 279
 280 /* Each target can link one of these into the table */
 281 struct dm_target_callbacks {
 282         struct list_head list;
 283         int (*congested_fn) (struct dm_target_callbacks *, int);
 284 };
 285
 286 /*
 287  * For bio-based dm.
 288  * One of these is allocated for each bio.
 289  * This structure shouldn't be touched directly by target drivers.
 290  * It is here so that we can inline dm_per_bio_data and
 291  * dm_bio_from_per_bio_data
 292  */
 293 struct dm_target_io {
 294         struct dm_io *io;
 295         struct dm_target *ti;
 296         unsigned target_bio_nr;
 297         unsigned *len_ptr;
 298         struct bio clone;
 299 };
 300
 301 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
 302 {
 303         return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
 304 }
 305
 306 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
 307 {
 308         return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
 309 }
 310
 311 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
 312 {
 313         return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
 314 }
 315
 316 int dm_register_target(struct target_type *t);
 317 void dm_unregister_target(struct target_type *t);
 318
 319 /*
 320  * Target argument parsing.
 321  */
 322 struct dm_arg_set {
 323         unsigned argc;
 324         char **argv;
 325 };
 326
 327 /*
 328  * The minimum and maximum value of a numeric argument, together with
 329  * the error message to use if the number is found to be outside that range.
 330  */
 331 struct dm_arg {
 332         unsigned min;
 333         unsigned max;
 334         char *error;
 335 };
 336
 337 /*
 338  * Validate the next argument, either returning it as *value or, if invalid,
 339  * returning -EINVAL and setting *error.
 340  */
 341 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 342                 unsigned *value, char **error);
 343
 344 /*
 345  * Process the next argument as the start of a group containing between
 346  * arg->min and arg->max further arguments. Either return the size as
 347  * *num_args or, if invalid, return -EINVAL and set *error.
 348  */
 349 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 350                       unsigned *num_args, char **error);
 351
 352 /*
 353  * Return the current argument and shift to the next.
 354  */
 355 const char *dm_shift_arg(struct dm_arg_set *as);
 356
 357 /*
 358  * Move through num_args arguments.
 359  */
 360 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 361
 362 /*-----------------------------------------------------------------
 363  * Functions for creating and manipulating mapped devices.
 364  * Drop the reference with dm_put when you finish with the object.
 365  *---------------------------------------------------------------*/
 366
 367 /*
 368  * DM_ANY_MINOR chooses the next available minor number.
 369  */
 370 #define DM_ANY_MINOR (-1)
 371 int dm_create(int minor, struct mapped_device **md);
 372
 373 /*
 374  * Reference counting for md.
 375  */
 376 struct mapped_device *dm_get_md(dev_t dev);
 377 void dm_get(struct mapped_device *md);
 378 int dm_hold(struct mapped_device *md);
 379 void dm_put(struct mapped_device *md);
 380
 381 /*
 382  * An arbitrary pointer may be stored alongside a mapped device.
 383  */
 384 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 385 void *dm_get_mdptr(struct mapped_device *md);
 386
 387 /*
 388  * A device can still be used while suspended, but I/O is deferred.
 389  */
 390 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 391 int dm_resume(struct mapped_device *md);
 392
 393 /*
 394  * Event functions.
 395  */
 396 uint32_t dm_get_event_nr(struct mapped_device *md);
 397 int dm_wait_event(struct mapped_device *md, int event_nr);
 398 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 399 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 400
 401 /*
 402  * Info functions.
 403  */
 404 const char *dm_device_name(struct mapped_device *md);
 405 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 406 struct gendisk *dm_disk(struct mapped_device *md);
 407 int dm_suspended(struct dm_target *ti);
 408 int dm_noflush_suspending(struct dm_target *ti);
 409 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
 410 union map_info *dm_get_rq_mapinfo(struct request *rq);
 411
 412 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
 413
 414 /*
 415  * Geometry functions.
 416  */
 417 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 418 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 419
 420 /*-----------------------------------------------------------------
 421  * Functions for manipulating device-mapper tables.
 422  *---------------------------------------------------------------*/
 423
 424 /*
 425  * First create an empty table.
 426  */
 427 int dm_table_create(struct dm_table **result, fmode_t mode,
 428                     unsigned num_targets, struct mapped_device *md);
 429
 430 /*
 431  * Then call this once for each target.
 432  */
 433 int dm_table_add_target(struct dm_table *t, const char *type,
 434                         sector_t start, sector_t len, char *params);
 435
 436 /*
 437  * Target_ctr should call this if it needs to add any callbacks.
 438  */
 439 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 440
 441 /*
 442  * Finally call this to make the table ready for use.
 443  */
 444 int dm_table_complete(struct dm_table *t);
 445
 446 /*
 447  * Target may require that it is never sent I/O larger than len.
 448  */
 449 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 450
 451 /*
 452  * Table reference counting.
 453  */
 454 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
 455 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
 456 void dm_sync_table(struct mapped_device *md);
 457
 458 /*
 459  * Queries
 460  */
 461 sector_t dm_table_get_size(struct dm_table *t);
 462 unsigned int dm_table_get_num_targets(struct dm_table *t);
 463 fmode_t dm_table_get_mode(struct dm_table *t);
 464 struct mapped_device *dm_table_get_md(struct dm_table *t);
 465
 466 /*
 467  * Trigger an event.
 468  */
 469 void dm_table_event(struct dm_table *t);
 470
 471 /*
 472  * Run the queue for request-based targets.
 473  */
 474 void dm_table_run_md_queue_async(struct dm_table *t);
 475
 476 /*
 477  * The device must be suspended before calling this method.
 478  * Returns the previous table, which the caller must destroy.
 479  */
 480 struct dm_table *dm_swap_table(struct mapped_device *md,
 481                                struct dm_table *t);
 482
 483 /*
 484  * A wrapper around vmalloc.
 485  */
 486 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 487
 488 /*-----------------------------------------------------------------
 489  * Macros.
 490  *---------------------------------------------------------------*/
 491 #define DM_NAME "device-mapper"
 492
 493 #ifdef CONFIG_PRINTK
 494 extern struct ratelimit_state dm_ratelimit_state;
 495
 496 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 497 #else
 498 #define dm_ratelimit()  0
 499 #endif
 500
 501 #define DMCRIT(f, arg...) \
 502         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 503
 504 #define DMERR(f, arg...) \
 505         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 506 #define DMERR_LIMIT(f, arg...) \
 507         do { \
 508                 if (dm_ratelimit())     \
 509                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 510                                f "\n", ## arg); \
 511         } while (0)
 512
 513 #define DMWARN(f, arg...) \
 514         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 515 #define DMWARN_LIMIT(f, arg...) \
 516         do { \
 517                 if (dm_ratelimit())     \
 518                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 519                                f "\n", ## arg); \
 520         } while (0)
 521
 522 #define DMINFO(f, arg...) \
 523         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 524 #define DMINFO_LIMIT(f, arg...) \
 525         do { \
 526                 if (dm_ratelimit())     \
 527                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 528                                "\n", ## arg); \
 529         } while (0)
 530
 531 #ifdef CONFIG_DM_DEBUG
 532 #  define DMDEBUG(f, arg...) \
 533         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 534 #  define DMDEBUG_LIMIT(f, arg...) \
 535         do { \
 536                 if (dm_ratelimit())     \
 537                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 538                                "\n", ## arg); \
 539         } while (0)
 540 #else
 541 #  define DMDEBUG(f, arg...) do {} while (0)
 542 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 543 #endif
 544
 545 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 546                           0 : scnprintf(result + sz, maxlen - sz, x))
 547
 548 #define SECTOR_SHIFT 9
 549
 550 /*
 551  * Definitions of return values from target end_io function.
 552  */
 553 #define DM_ENDIO_INCOMPLETE     1
 554 #define DM_ENDIO_REQUEUE        2
 555
 556 /*
 557  * Definitions of return values from target map function.
 558  */
 559 #define DM_MAPIO_SUBMITTED      0
 560 #define DM_MAPIO_REMAPPED       1
 561 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 562
 563 #define dm_sector_div64(x, y)( \
 564 { \
 565         u64 _res; \
 566         (x) = div64_u64_rem(x, y, &_res); \
 567         _res; \
 568 } \
 569 )
 570
 571 /*
 572  * Ceiling(n / sz)
 573  */
 574 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 575
 576 #define dm_sector_div_up(n, sz) ( \
 577 { \
 578         sector_t _r = ((n) + (sz) - 1); \
 579         sector_div(_r, (sz)); \
 580         _r; \
 581 } \
 582 )
 583
 584 /*
 585  * ceiling(n / size) * size
 586  */
 587 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 588
 589 #define dm_array_too_big(fixed, obj, num) \
 590         ((num) > (UINT_MAX - (fixed)) / (obj))
 591
 592 /*
 593  * Sector offset taken relative to the start of the target instead of
 594  * relative to the start of the device.
 595  */
 596 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 597
 598 static inline sector_t to_sector(unsigned long n)
 599 {
 600         return (n >> SECTOR_SHIFT);
 601 }
 602
 603 static inline unsigned long to_bytes(sector_t n)
 604 {
 605         return (n << SECTOR_SHIFT);
 606 }
 607
 608 /*-----------------------------------------------------------------
 609  * Helper for block layer and dm core operations
 610  *---------------------------------------------------------------*/
 611 int dm_underlying_device_busy(struct request_queue *q);
 612
 613 #endif  /* _LINUX_DEVICE_MAPPER_H */