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 /*
  23  * Type of table, mapped_device's mempool and request_queue
  24  */
  25 #define DM_TYPE_NONE                    0
  26 #define DM_TYPE_BIO_BASED               1
  27 #define DM_TYPE_REQUEST_BASED           2
  28 #define DM_TYPE_MQ_REQUEST_BASED        3
  29 #define DM_TYPE_DAX_BIO_BASED           4
  30
  31 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  32
  33 union map_info {
  34         void *ptr;
  35 };
  36
  37 /*
  38  * In the constructor the target parameter will already have the
  39  * table, type, begin and len fields filled in.
  40  */
  41 typedef int (*dm_ctr_fn) (struct dm_target *target,
  42                           unsigned int argc, char **argv);
  43
  44 /*
  45  * The destructor doesn't need to free the dm_target, just
  46  * anything hidden ti->private.
  47  */
  48 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  49
  50 /*
  51  * The map function must return:
  52  * < 0: error
  53  * = 0: The target will handle the io by resubmitting it later
  54  * = 1: simple remap complete
  55  * = 2: The target wants to push back the io
  56  */
  57 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio);
  58 typedef int (*dm_clone_and_map_request_fn) (struct dm_target *ti,
  59                                             struct request *rq,
  60                                             union map_info *map_context,
  61                                             struct request **clone);
  62 typedef void (*dm_release_clone_request_fn) (struct request *clone);
  63
  64 /*
  65  * Returns:
  66  * < 0 : error (currently ignored)
  67  * 0   : ended successfully
  68  * 1   : for some reason the io has still not completed (eg,
  69  *       multipath target might want to requeue a failed io).
  70  * 2   : The target wants to push back the io
  71  */
  72 typedef int (*dm_endio_fn) (struct dm_target *ti,
  73                             struct bio *bio, int error);
  74 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  75                                     struct request *clone, int error,
  76                                     union map_info *map_context);
  77
  78 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  79 typedef void (*dm_presuspend_undo_fn) (struct dm_target *ti);
  80 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  81 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  82 typedef void (*dm_resume_fn) (struct dm_target *ti);
  83
  84 typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  85                               unsigned status_flags, char *result, unsigned maxlen);
  86
  87 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  88
  89 typedef int (*dm_prepare_ioctl_fn) (struct dm_target *ti,
  90                             struct block_device **bdev, fmode_t *mode);
  91
  92 /*
  93  * These iteration functions are typically used to check (and combine)
  94  * properties of underlying devices.
  95  * E.g. Does at least one underlying device support flush?
  96  *      Does any underlying device not support WRITE_SAME?
  97  *
  98  * The callout function is called once for each contiguous section of
  99  * an underlying device.  State can be maintained in *data.
 100  * Return non-zero to stop iterating through any further devices.
 101  */
 102 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
 103                                            struct dm_dev *dev,
 104                                            sector_t start, sector_t len,
 105                                            void *data);
 106
 107 /*
 108  * This function must iterate through each section of device used by the
 109  * target until it encounters a non-zero return code, which it then returns.
 110  * Returns zero if no callout returned non-zero.
 111  */
 112 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
 113                                       iterate_devices_callout_fn fn,
 114                                       void *data);
 115
 116 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
 117                                 struct queue_limits *limits);
 118
 119 /*
 120  * Returns:
 121  *    0: The target can handle the next I/O immediately.
 122  *    1: The target can't handle the next I/O immediately.
 123  */
 124 typedef int (*dm_busy_fn) (struct dm_target *ti);
 125
 126 /*
 127  * Returns:
 128  *  < 0 : error
 129  * >= 0 : the number of bytes accessible at the address
 130  */
 131 typedef long (*dm_direct_access_fn) (struct dm_target *ti, sector_t sector,
 132                                      void **kaddr, pfn_t *pfn, long size);
 133
 134 void dm_error(const char *message);
 135
 136 struct dm_dev {
 137         struct block_device *bdev;
 138         fmode_t mode;
 139         char name[16];
 140 };
 141
 142 dev_t dm_get_dev_t(const char *path);
 143
 144 /*
 145  * Constructors should call these functions to ensure destination devices
 146  * are opened/closed correctly.
 147  */
 148 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 149                   struct dm_dev **result);
 150 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 151
 152 /*
 153  * Information about a target type
 154  */
 155
 156 struct target_type {
 157         uint64_t features;
 158         const char *name;
 159         struct module *module;
 160         unsigned version[3];
 161         dm_ctr_fn ctr;
 162         dm_dtr_fn dtr;
 163         dm_map_fn map;
 164         dm_clone_and_map_request_fn clone_and_map_rq;
 165         dm_release_clone_request_fn release_clone_rq;
 166         dm_endio_fn end_io;
 167         dm_request_endio_fn rq_end_io;
 168         dm_presuspend_fn presuspend;
 169         dm_presuspend_undo_fn presuspend_undo;
 170         dm_postsuspend_fn postsuspend;
 171         dm_preresume_fn preresume;
 172         dm_resume_fn resume;
 173         dm_status_fn status;
 174         dm_message_fn message;
 175         dm_prepare_ioctl_fn prepare_ioctl;
 176         dm_busy_fn busy;
 177         dm_iterate_devices_fn iterate_devices;
 178         dm_io_hints_fn io_hints;
 179         dm_direct_access_fn direct_access;
 180
 181         /* For internal device-mapper use. */
 182         struct list_head list;
 183 };
 184
 185 /*
 186  * Target features
 187  */
 188
 189 /*
 190  * Any table that contains an instance of this target must have only one.
 191  */
 192 #define DM_TARGET_SINGLETON             0x00000001
 193 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
 194
 195 /*
 196  * Indicates that a target does not support read-only devices.
 197  */
 198 #define DM_TARGET_ALWAYS_WRITEABLE      0x00000002
 199 #define dm_target_always_writeable(type) \
 200                 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
 201
 202 /*
 203  * Any device that contains a table with an instance of this target may never
 204  * have tables containing any different target type.
 205  */
 206 #define DM_TARGET_IMMUTABLE             0x00000004
 207 #define dm_target_is_immutable(type)    ((type)->features & DM_TARGET_IMMUTABLE)
 208
 209 /*
 210  * Indicates that a target may replace any target; even immutable targets.
 211  * .map, .map_rq, .clone_and_map_rq and .release_clone_rq are all defined.
 212  */
 213 #define DM_TARGET_WILDCARD              0x00000008
 214 #define dm_target_is_wildcard(type)     ((type)->features & DM_TARGET_WILDCARD)
 215
 216 /*
 217  * Some targets need to be sent the same WRITE bio severals times so
 218  * that they can send copies of it to different devices.  This function
 219  * examines any supplied bio and returns the number of copies of it the
 220  * target requires.
 221  */
 222 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
 223
 224 struct dm_target {
 225         struct dm_table *table;
 226         struct target_type *type;
 227
 228         /* target limits */
 229         sector_t begin;
 230         sector_t len;
 231
 232         /* If non-zero, maximum size of I/O submitted to a target. */
 233         uint32_t max_io_len;
 234
 235         /*
 236          * A number of zero-length barrier bios that will be submitted
 237          * to the target for the purpose of flushing cache.
 238          *
 239          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 240          * It is a responsibility of the target driver to remap these bios
 241          * to the real underlying devices.
 242          */
 243         unsigned num_flush_bios;
 244
 245         /*
 246          * The number of discard bios that will be submitted to the target.
 247          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 248          */
 249         unsigned num_discard_bios;
 250
 251         /*
 252          * The number of WRITE SAME bios that will be submitted to the target.
 253          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 254          */
 255         unsigned num_write_same_bios;
 256
 257         /*
 258          * The minimum number of extra bytes allocated in each io for the
 259          * target to use.
 260          */
 261         unsigned per_io_data_size;
 262
 263         /*
 264          * If defined, this function is called to find out how many
 265          * duplicate bios should be sent to the target when writing
 266          * data.
 267          */
 268         dm_num_write_bios_fn num_write_bios;
 269
 270         /* target specific data */
 271         void *private;
 272
 273         /* Used to provide an error string from the ctr */
 274         char *error;
 275
 276         /*
 277          * Set if this target needs to receive flushes regardless of
 278          * whether or not its underlying devices have support.
 279          */
 280         bool flush_supported:1;
 281
 282         /*
 283          * Set if this target needs to receive discards regardless of
 284          * whether or not its underlying devices have support.
 285          */
 286         bool discards_supported:1;
 287
 288         /*
 289          * Set if the target required discard bios to be split
 290          * on max_io_len boundary.
 291          */
 292         bool split_discard_bios:1;
 293
 294         /*
 295          * Set if this target does not return zeroes on discarded blocks.
 296          */
 297         bool discard_zeroes_data_unsupported:1;
 298 };
 299
 300 /* Each target can link one of these into the table */
 301 struct dm_target_callbacks {
 302         struct list_head list;
 303         int (*congested_fn) (struct dm_target_callbacks *, int);
 304 };
 305
 306 /*
 307  * For bio-based dm.
 308  * One of these is allocated for each bio.
 309  * This structure shouldn't be touched directly by target drivers.
 310  * It is here so that we can inline dm_per_bio_data and
 311  * dm_bio_from_per_bio_data
 312  */
 313 struct dm_target_io {
 314         struct dm_io *io;
 315         struct dm_target *ti;
 316         unsigned target_bio_nr;
 317         unsigned *len_ptr;
 318         struct bio clone;
 319 };
 320
 321 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
 322 {
 323         return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
 324 }
 325
 326 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
 327 {
 328         return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
 329 }
 330
 331 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
 332 {
 333         return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
 334 }
 335
 336 int dm_register_target(struct target_type *t);
 337 void dm_unregister_target(struct target_type *t);
 338
 339 /*
 340  * Target argument parsing.
 341  */
 342 struct dm_arg_set {
 343         unsigned argc;
 344         char **argv;
 345 };
 346
 347 /*
 348  * The minimum and maximum value of a numeric argument, together with
 349  * the error message to use if the number is found to be outside that range.
 350  */
 351 struct dm_arg {
 352         unsigned min;
 353         unsigned max;
 354         char *error;
 355 };
 356
 357 /*
 358  * Validate the next argument, either returning it as *value or, if invalid,
 359  * returning -EINVAL and setting *error.
 360  */
 361 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 362                 unsigned *value, char **error);
 363
 364 /*
 365  * Process the next argument as the start of a group containing between
 366  * arg->min and arg->max further arguments. Either return the size as
 367  * *num_args or, if invalid, return -EINVAL and set *error.
 368  */
 369 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 370                       unsigned *num_args, char **error);
 371
 372 /*
 373  * Return the current argument and shift to the next.
 374  */
 375 const char *dm_shift_arg(struct dm_arg_set *as);
 376
 377 /*
 378  * Move through num_args arguments.
 379  */
 380 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 381
 382 /*-----------------------------------------------------------------
 383  * Functions for creating and manipulating mapped devices.
 384  * Drop the reference with dm_put when you finish with the object.
 385  *---------------------------------------------------------------*/
 386
 387 /*
 388  * DM_ANY_MINOR chooses the next available minor number.
 389  */
 390 #define DM_ANY_MINOR (-1)
 391 int dm_create(int minor, struct mapped_device **md);
 392
 393 /*
 394  * Reference counting for md.
 395  */
 396 struct mapped_device *dm_get_md(dev_t dev);
 397 void dm_get(struct mapped_device *md);
 398 int dm_hold(struct mapped_device *md);
 399 void dm_put(struct mapped_device *md);
 400
 401 /*
 402  * An arbitrary pointer may be stored alongside a mapped device.
 403  */
 404 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 405 void *dm_get_mdptr(struct mapped_device *md);
 406
 407 /*
 408  * A device can still be used while suspended, but I/O is deferred.
 409  */
 410 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 411 int dm_resume(struct mapped_device *md);
 412
 413 /*
 414  * Event functions.
 415  */
 416 uint32_t dm_get_event_nr(struct mapped_device *md);
 417 int dm_wait_event(struct mapped_device *md, int event_nr);
 418 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 419 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 420
 421 /*
 422  * Info functions.
 423  */
 424 const char *dm_device_name(struct mapped_device *md);
 425 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 426 struct gendisk *dm_disk(struct mapped_device *md);
 427 int dm_suspended(struct dm_target *ti);
 428 int dm_noflush_suspending(struct dm_target *ti);
 429 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
 430 union map_info *dm_get_rq_mapinfo(struct request *rq);
 431
 432 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
 433
 434 /*
 435  * Geometry functions.
 436  */
 437 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 438 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 439
 440 /*-----------------------------------------------------------------
 441  * Functions for manipulating device-mapper tables.
 442  *---------------------------------------------------------------*/
 443
 444 /*
 445  * First create an empty table.
 446  */
 447 int dm_table_create(struct dm_table **result, fmode_t mode,
 448                     unsigned num_targets, struct mapped_device *md);
 449
 450 /*
 451  * Then call this once for each target.
 452  */
 453 int dm_table_add_target(struct dm_table *t, const char *type,
 454                         sector_t start, sector_t len, char *params);
 455
 456 /*
 457  * Target_ctr should call this if it needs to add any callbacks.
 458  */
 459 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 460
 461 /*
 462  * Target can use this to set the table's type.
 463  * Can only ever be called from a target's ctr.
 464  * Useful for "hybrid" target (supports both bio-based
 465  * and request-based).
 466  */
 467 void dm_table_set_type(struct dm_table *t, unsigned type);
 468
 469 /*
 470  * Finally call this to make the table ready for use.
 471  */
 472 int dm_table_complete(struct dm_table *t);
 473
 474 /*
 475  * Target may require that it is never sent I/O larger than len.
 476  */
 477 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 478
 479 /*
 480  * Table reference counting.
 481  */
 482 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
 483 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
 484 void dm_sync_table(struct mapped_device *md);
 485
 486 /*
 487  * Queries
 488  */
 489 sector_t dm_table_get_size(struct dm_table *t);
 490 unsigned int dm_table_get_num_targets(struct dm_table *t);
 491 fmode_t dm_table_get_mode(struct dm_table *t);
 492 struct mapped_device *dm_table_get_md(struct dm_table *t);
 493
 494 /*
 495  * Trigger an event.
 496  */
 497 void dm_table_event(struct dm_table *t);
 498
 499 /*
 500  * Run the queue for request-based targets.
 501  */
 502 void dm_table_run_md_queue_async(struct dm_table *t);
 503
 504 /*
 505  * The device must be suspended before calling this method.
 506  * Returns the previous table, which the caller must destroy.
 507  */
 508 struct dm_table *dm_swap_table(struct mapped_device *md,
 509                                struct dm_table *t);
 510
 511 /*
 512  * A wrapper around vmalloc.
 513  */
 514 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 515
 516 /*-----------------------------------------------------------------
 517  * Macros.
 518  *---------------------------------------------------------------*/
 519 #define DM_NAME "device-mapper"
 520
 521 #ifdef CONFIG_PRINTK
 522 extern struct ratelimit_state dm_ratelimit_state;
 523
 524 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 525 #else
 526 #define dm_ratelimit()  0
 527 #endif
 528
 529 #define DMCRIT(f, arg...) \
 530         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 531
 532 #define DMERR(f, arg...) \
 533         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 534 #define DMERR_LIMIT(f, arg...) \
 535         do { \
 536                 if (dm_ratelimit())     \
 537                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 538                                f "\n", ## arg); \
 539         } while (0)
 540
 541 #define DMWARN(f, arg...) \
 542         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 543 #define DMWARN_LIMIT(f, arg...) \
 544         do { \
 545                 if (dm_ratelimit())     \
 546                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 547                                f "\n", ## arg); \
 548         } while (0)
 549
 550 #define DMINFO(f, arg...) \
 551         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 552 #define DMINFO_LIMIT(f, arg...) \
 553         do { \
 554                 if (dm_ratelimit())     \
 555                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 556                                "\n", ## arg); \
 557         } while (0)
 558
 559 #ifdef CONFIG_DM_DEBUG
 560 #  define DMDEBUG(f, arg...) \
 561         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 562 #  define DMDEBUG_LIMIT(f, arg...) \
 563         do { \
 564                 if (dm_ratelimit())     \
 565                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 566                                "\n", ## arg); \
 567         } while (0)
 568 #else
 569 #  define DMDEBUG(f, arg...) do {} while (0)
 570 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 571 #endif
 572
 573 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 574                           0 : scnprintf(result + sz, maxlen - sz, x))
 575
 576 #define SECTOR_SHIFT 9
 577
 578 /*
 579  * Definitions of return values from target end_io function.
 580  */
 581 #define DM_ENDIO_INCOMPLETE     1
 582 #define DM_ENDIO_REQUEUE        2
 583
 584 /*
 585  * Definitions of return values from target map function.
 586  */
 587 #define DM_MAPIO_SUBMITTED      0
 588 #define DM_MAPIO_REMAPPED       1
 589 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 590 #define DM_MAPIO_DELAY_REQUEUE  3
 591
 592 #define dm_sector_div64(x, y)( \
 593 { \
 594         u64 _res; \
 595         (x) = div64_u64_rem(x, y, &_res); \
 596         _res; \
 597 } \
 598 )
 599
 600 /*
 601  * Ceiling(n / sz)
 602  */
 603 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 604
 605 #define dm_sector_div_up(n, sz) ( \
 606 { \
 607         sector_t _r = ((n) + (sz) - 1); \
 608         sector_div(_r, (sz)); \
 609         _r; \
 610 } \
 611 )
 612
 613 /*
 614  * ceiling(n / size) * size
 615  */
 616 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 617
 618 #define dm_array_too_big(fixed, obj, num) \
 619         ((num) > (UINT_MAX - (fixed)) / (obj))
 620
 621 /*
 622  * Sector offset taken relative to the start of the target instead of
 623  * relative to the start of the device.
 624  */
 625 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 626
 627 static inline sector_t to_sector(unsigned long n)
 628 {
 629         return (n >> SECTOR_SHIFT);
 630 }
 631
 632 static inline unsigned long to_bytes(sector_t n)
 633 {
 634         return (n << SECTOR_SHIFT);
 635 }
 636
 637 #endif  /* _LINUX_DEVICE_MAPPER_H */