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 enum dm_queue_mode {
  26         DM_TYPE_NONE             = 0,
  27         DM_TYPE_BIO_BASED        = 1,
  28         DM_TYPE_REQUEST_BASED    = 2,
  29         DM_TYPE_MQ_REQUEST_BASED = 3,
  30         DM_TYPE_DAX_BIO_BASED    = 4,
  31 };
  32
  33 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  34
  35 union map_info {
  36         void *ptr;
  37 };
  38
  39 /*
  40  * In the constructor the target parameter will already have the
  41  * table, type, begin and len fields filled in.
  42  */
  43 typedef int (*dm_ctr_fn) (struct dm_target *target,
  44                           unsigned int argc, char **argv);
  45
  46 /*
  47  * The destructor doesn't need to free the dm_target, just
  48  * anything hidden ti->private.
  49  */
  50 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  51
  52 /*
  53  * The map function must return:
  54  * < 0: error
  55  * = 0: The target will handle the io by resubmitting it later
  56  * = 1: simple remap complete
  57  * = 2: The target wants to push back the io
  58  */
  59 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio);
  60 typedef int (*dm_clone_and_map_request_fn) (struct dm_target *ti,
  61                                             struct request *rq,
  62                                             union map_info *map_context,
  63                                             struct request **clone);
  64 typedef void (*dm_release_clone_request_fn) (struct request *clone);
  65
  66 /*
  67  * Returns:
  68  * < 0 : error (currently ignored)
  69  * 0   : ended successfully
  70  * 1   : for some reason the io has still not completed (eg,
  71  *       multipath target might want to requeue a failed io).
  72  * 2   : The target wants to push back the io
  73  */
  74 typedef int (*dm_endio_fn) (struct dm_target *ti,
  75                             struct bio *bio, blk_status_t *error);
  76 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  77                                     struct request *clone, blk_status_t error,
  78                                     union map_info *map_context);
  79
  80 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  81 typedef void (*dm_presuspend_undo_fn) (struct dm_target *ti);
  82 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  83 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  84 typedef void (*dm_resume_fn) (struct dm_target *ti);
  85
  86 typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  87                               unsigned status_flags, char *result, unsigned maxlen);
  88
  89 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  90
  91 typedef int (*dm_prepare_ioctl_fn) (struct dm_target *ti,
  92                             struct block_device **bdev, fmode_t *mode);
  93
  94 /*
  95  * These iteration functions are typically used to check (and combine)
  96  * properties of underlying devices.
  97  * E.g. Does at least one underlying device support flush?
  98  *      Does any underlying device not support WRITE_SAME?
  99  *
 100  * The callout function is called once for each contiguous section of
 101  * an underlying device.  State can be maintained in *data.
 102  * Return non-zero to stop iterating through any further devices.
 103  */
 104 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
 105                                            struct dm_dev *dev,
 106                                            sector_t start, sector_t len,
 107                                            void *data);
 108
 109 /*
 110  * This function must iterate through each section of device used by the
 111  * target until it encounters a non-zero return code, which it then returns.
 112  * Returns zero if no callout returned non-zero.
 113  */
 114 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
 115                                       iterate_devices_callout_fn fn,
 116                                       void *data);
 117
 118 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
 119                                 struct queue_limits *limits);
 120
 121 /*
 122  * Returns:
 123  *    0: The target can handle the next I/O immediately.
 124  *    1: The target can't handle the next I/O immediately.
 125  */
 126 typedef int (*dm_busy_fn) (struct dm_target *ti);
 127
 128 /*
 129  * Returns:
 130  *  < 0 : error
 131  * >= 0 : the number of bytes accessible at the address
 132  */
 133 typedef long (*dm_dax_direct_access_fn) (struct dm_target *ti, pgoff_t pgoff,
 134                 long nr_pages, void **kaddr, pfn_t *pfn);
 135 typedef size_t (*dm_dax_copy_from_iter_fn)(struct dm_target *ti, pgoff_t pgoff,
 136                 void *addr, size_t bytes, struct iov_iter *i);
 137 typedef void (*dm_dax_flush_fn)(struct dm_target *ti, pgoff_t pgoff, void *addr,
 138                 size_t size);
 139 #define PAGE_SECTORS (PAGE_SIZE / 512)
 140
 141 void dm_error(const char *message);
 142
 143 struct dm_dev {
 144         struct block_device *bdev;
 145         struct dax_device *dax_dev;
 146         fmode_t mode;
 147         char name[16];
 148 };
 149
 150 dev_t dm_get_dev_t(const char *path);
 151
 152 /*
 153  * Constructors should call these functions to ensure destination devices
 154  * are opened/closed correctly.
 155  */
 156 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 157                   struct dm_dev **result);
 158 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 159
 160 /*
 161  * Information about a target type
 162  */
 163
 164 struct target_type {
 165         uint64_t features;
 166         const char *name;
 167         struct module *module;
 168         unsigned version[3];
 169         dm_ctr_fn ctr;
 170         dm_dtr_fn dtr;
 171         dm_map_fn map;
 172         dm_clone_and_map_request_fn clone_and_map_rq;
 173         dm_release_clone_request_fn release_clone_rq;
 174         dm_endio_fn end_io;
 175         dm_request_endio_fn rq_end_io;
 176         dm_presuspend_fn presuspend;
 177         dm_presuspend_undo_fn presuspend_undo;
 178         dm_postsuspend_fn postsuspend;
 179         dm_preresume_fn preresume;
 180         dm_resume_fn resume;
 181         dm_status_fn status;
 182         dm_message_fn message;
 183         dm_prepare_ioctl_fn prepare_ioctl;
 184         dm_busy_fn busy;
 185         dm_iterate_devices_fn iterate_devices;
 186         dm_io_hints_fn io_hints;
 187         dm_dax_direct_access_fn direct_access;
 188         dm_dax_copy_from_iter_fn dax_copy_from_iter;
 189         dm_dax_flush_fn dax_flush;
 190
 191         /* For internal device-mapper use. */
 192         struct list_head list;
 193 };
 194
 195 /*
 196  * Target features
 197  */
 198
 199 /*
 200  * Any table that contains an instance of this target must have only one.
 201  */
 202 #define DM_TARGET_SINGLETON             0x00000001
 203 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
 204
 205 /*
 206  * Indicates that a target does not support read-only devices.
 207  */
 208 #define DM_TARGET_ALWAYS_WRITEABLE      0x00000002
 209 #define dm_target_always_writeable(type) \
 210                 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
 211
 212 /*
 213  * Any device that contains a table with an instance of this target may never
 214  * have tables containing any different target type.
 215  */
 216 #define DM_TARGET_IMMUTABLE             0x00000004
 217 #define dm_target_is_immutable(type)    ((type)->features & DM_TARGET_IMMUTABLE)
 218
 219 /*
 220  * Indicates that a target may replace any target; even immutable targets.
 221  * .map, .map_rq, .clone_and_map_rq and .release_clone_rq are all defined.
 222  */
 223 #define DM_TARGET_WILDCARD              0x00000008
 224 #define dm_target_is_wildcard(type)     ((type)->features & DM_TARGET_WILDCARD)
 225
 226 /*
 227  * Some targets need to be sent the same WRITE bio severals times so
 228  * that they can send copies of it to different devices.  This function
 229  * examines any supplied bio and returns the number of copies of it the
 230  * target requires.
 231  */
 232 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
 233
 234 /*
 235  * A target implements own bio data integrity.
 236  */
 237 #define DM_TARGET_INTEGRITY             0x00000010
 238 #define dm_target_has_integrity(type)   ((type)->features & DM_TARGET_INTEGRITY)
 239
 240 /*
 241  * A target passes integrity data to the lower device.
 242  */
 243 #define DM_TARGET_PASSES_INTEGRITY      0x00000020
 244 #define dm_target_passes_integrity(type) ((type)->features & DM_TARGET_PASSES_INTEGRITY)
 245
 246 /*
 247  * Indicates that a target supports host-managed zoned block devices.
 248  */
 249 #define DM_TARGET_ZONED_HM              0x00000040
 250 #define dm_target_supports_zoned_hm(type) ((type)->features & DM_TARGET_ZONED_HM)
 251
 252 struct dm_target {
 253         struct dm_table *table;
 254         struct target_type *type;
 255
 256         /* target limits */
 257         sector_t begin;
 258         sector_t len;
 259
 260         /* If non-zero, maximum size of I/O submitted to a target. */
 261         uint32_t max_io_len;
 262
 263         /*
 264          * A number of zero-length barrier bios that will be submitted
 265          * to the target for the purpose of flushing cache.
 266          *
 267          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 268          * It is a responsibility of the target driver to remap these bios
 269          * to the real underlying devices.
 270          */
 271         unsigned num_flush_bios;
 272
 273         /*
 274          * The number of discard bios that will be submitted to the target.
 275          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 276          */
 277         unsigned num_discard_bios;
 278
 279         /*
 280          * The number of WRITE SAME bios that will be submitted to the target.
 281          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 282          */
 283         unsigned num_write_same_bios;
 284
 285         /*
 286          * The number of WRITE ZEROES bios that will be submitted to the target.
 287          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 288          */
 289         unsigned num_write_zeroes_bios;
 290
 291         /*
 292          * The minimum number of extra bytes allocated in each io for the
 293          * target to use.
 294          */
 295         unsigned per_io_data_size;
 296
 297         /*
 298          * If defined, this function is called to find out how many
 299          * duplicate bios should be sent to the target when writing
 300          * data.
 301          */
 302         dm_num_write_bios_fn num_write_bios;
 303
 304         /* target specific data */
 305         void *private;
 306
 307         /* Used to provide an error string from the ctr */
 308         char *error;
 309
 310         /*
 311          * Set if this target needs to receive flushes regardless of
 312          * whether or not its underlying devices have support.
 313          */
 314         bool flush_supported:1;
 315
 316         /*
 317          * Set if this target needs to receive discards regardless of
 318          * whether or not its underlying devices have support.
 319          */
 320         bool discards_supported:1;
 321
 322         /*
 323          * Set if the target required discard bios to be split
 324          * on max_io_len boundary.
 325          */
 326         bool split_discard_bios:1;
 327 };
 328
 329 /* Each target can link one of these into the table */
 330 struct dm_target_callbacks {
 331         struct list_head list;
 332         int (*congested_fn) (struct dm_target_callbacks *, int);
 333 };
 334
 335 /*
 336  * For bio-based dm.
 337  * One of these is allocated for each bio.
 338  * This structure shouldn't be touched directly by target drivers.
 339  * It is here so that we can inline dm_per_bio_data and
 340  * dm_bio_from_per_bio_data
 341  */
 342 struct dm_target_io {
 343         struct dm_io *io;
 344         struct dm_target *ti;
 345         unsigned target_bio_nr;
 346         unsigned *len_ptr;
 347         struct bio clone;
 348 };
 349
 350 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
 351 {
 352         return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
 353 }
 354
 355 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
 356 {
 357         return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
 358 }
 359
 360 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
 361 {
 362         return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
 363 }
 364
 365 int dm_register_target(struct target_type *t);
 366 void dm_unregister_target(struct target_type *t);
 367
 368 /*
 369  * Target argument parsing.
 370  */
 371 struct dm_arg_set {
 372         unsigned argc;
 373         char **argv;
 374 };
 375
 376 /*
 377  * The minimum and maximum value of a numeric argument, together with
 378  * the error message to use if the number is found to be outside that range.
 379  */
 380 struct dm_arg {
 381         unsigned min;
 382         unsigned max;
 383         char *error;
 384 };
 385
 386 /*
 387  * Validate the next argument, either returning it as *value or, if invalid,
 388  * returning -EINVAL and setting *error.
 389  */
 390 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 391                 unsigned *value, char **error);
 392
 393 /*
 394  * Process the next argument as the start of a group containing between
 395  * arg->min and arg->max further arguments. Either return the size as
 396  * *num_args or, if invalid, return -EINVAL and set *error.
 397  */
 398 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 399                       unsigned *num_args, char **error);
 400
 401 /*
 402  * Return the current argument and shift to the next.
 403  */
 404 const char *dm_shift_arg(struct dm_arg_set *as);
 405
 406 /*
 407  * Move through num_args arguments.
 408  */
 409 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 410
 411 /*-----------------------------------------------------------------
 412  * Functions for creating and manipulating mapped devices.
 413  * Drop the reference with dm_put when you finish with the object.
 414  *---------------------------------------------------------------*/
 415
 416 /*
 417  * DM_ANY_MINOR chooses the next available minor number.
 418  */
 419 #define DM_ANY_MINOR (-1)
 420 int dm_create(int minor, struct mapped_device **md);
 421
 422 /*
 423  * Reference counting for md.
 424  */
 425 struct mapped_device *dm_get_md(dev_t dev);
 426 void dm_get(struct mapped_device *md);
 427 int dm_hold(struct mapped_device *md);
 428 void dm_put(struct mapped_device *md);
 429
 430 /*
 431  * An arbitrary pointer may be stored alongside a mapped device.
 432  */
 433 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 434 void *dm_get_mdptr(struct mapped_device *md);
 435
 436 /*
 437  * A device can still be used while suspended, but I/O is deferred.
 438  */
 439 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 440 int dm_resume(struct mapped_device *md);
 441
 442 /*
 443  * Event functions.
 444  */
 445 uint32_t dm_get_event_nr(struct mapped_device *md);
 446 int dm_wait_event(struct mapped_device *md, int event_nr);
 447 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 448 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 449
 450 /*
 451  * Info functions.
 452  */
 453 const char *dm_device_name(struct mapped_device *md);
 454 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 455 struct gendisk *dm_disk(struct mapped_device *md);
 456 int dm_suspended(struct dm_target *ti);
 457 int dm_noflush_suspending(struct dm_target *ti);
 458 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
 459 void dm_remap_zone_report(struct dm_target *ti, struct bio *bio,
 460                           sector_t start);
 461 union map_info *dm_get_rq_mapinfo(struct request *rq);
 462
 463 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
 464
 465 /*
 466  * Geometry functions.
 467  */
 468 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 469 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 470
 471 /*-----------------------------------------------------------------
 472  * Functions for manipulating device-mapper tables.
 473  *---------------------------------------------------------------*/
 474
 475 /*
 476  * First create an empty table.
 477  */
 478 int dm_table_create(struct dm_table **result, fmode_t mode,
 479                     unsigned num_targets, struct mapped_device *md);
 480
 481 /*
 482  * Then call this once for each target.
 483  */
 484 int dm_table_add_target(struct dm_table *t, const char *type,
 485                         sector_t start, sector_t len, char *params);
 486
 487 /*
 488  * Target_ctr should call this if it needs to add any callbacks.
 489  */
 490 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 491
 492 /*
 493  * Target can use this to set the table's type.
 494  * Can only ever be called from a target's ctr.
 495  * Useful for "hybrid" target (supports both bio-based
 496  * and request-based).
 497  */
 498 void dm_table_set_type(struct dm_table *t, enum dm_queue_mode type);
 499
 500 /*
 501  * Finally call this to make the table ready for use.
 502  */
 503 int dm_table_complete(struct dm_table *t);
 504
 505 /*
 506  * Target may require that it is never sent I/O larger than len.
 507  */
 508 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 509
 510 /*
 511  * Table reference counting.
 512  */
 513 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
 514 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
 515 void dm_sync_table(struct mapped_device *md);
 516
 517 /*
 518  * Queries
 519  */
 520 sector_t dm_table_get_size(struct dm_table *t);
 521 unsigned int dm_table_get_num_targets(struct dm_table *t);
 522 fmode_t dm_table_get_mode(struct dm_table *t);
 523 struct mapped_device *dm_table_get_md(struct dm_table *t);
 524
 525 /*
 526  * Trigger an event.
 527  */
 528 void dm_table_event(struct dm_table *t);
 529
 530 /*
 531  * Run the queue for request-based targets.
 532  */
 533 void dm_table_run_md_queue_async(struct dm_table *t);
 534
 535 /*
 536  * The device must be suspended before calling this method.
 537  * Returns the previous table, which the caller must destroy.
 538  */
 539 struct dm_table *dm_swap_table(struct mapped_device *md,
 540                                struct dm_table *t);
 541
 542 /*
 543  * A wrapper around vmalloc.
 544  */
 545 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 546
 547 /*-----------------------------------------------------------------
 548  * Macros.
 549  *---------------------------------------------------------------*/
 550 #define DM_NAME "device-mapper"
 551
 552 #ifdef CONFIG_PRINTK
 553 extern struct ratelimit_state dm_ratelimit_state;
 554
 555 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 556 #else
 557 #define dm_ratelimit()  0
 558 #endif
 559
 560 #define DM_FMT(fmt) DM_NAME ": " DM_MSG_PREFIX ": " fmt "\n"
 561
 562 #define DMCRIT(fmt, ...) pr_crit(DM_FMT(fmt), ##__VA_ARGS__)
 563
 564 #define DMERR(fmt, ...) pr_err(DM_FMT(fmt), ##__VA_ARGS__)
 565 #define DMERR_LIMIT(fmt, ...)                                           \
 566 do {                                                                    \
 567         if (dm_ratelimit())                                             \
 568                 DMERR(fmt, ##__VA_ARGS__);                              \
 569 } while (0)
 570
 571 #define DMWARN(fmt, ...) pr_warn(DM_FMT(fmt), ##__VA_ARGS__)
 572 #define DMWARN_LIMIT(fmt, ...)                                          \
 573 do {                                                                    \
 574         if (dm_ratelimit())                                             \
 575                 DMWARN(fmt, ##__VA_ARGS__);                             \
 576 } while (0)
 577
 578 #define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
 579 #define DMINFO_LIMIT(fmt, ...)                                          \
 580 do {                                                                    \
 581         if (dm_ratelimit())                                             \
 582                 DMINFO(fmt, ##__VA_ARGS__);                             \
 583 } while (0)
 584
 585 #ifdef CONFIG_DM_DEBUG
 586 #define DMDEBUG(fmt, ...) printk(KERN_DEBUG DM_FMT(fmt), ##__VA_ARGS__)
 587 #define DMDEBUG_LIMIT(fmt, ...)                                         \
 588 do {                                                                    \
 589         if (dm_ratelimit())                                             \
 590                 DMDEBUG(fmt, ##__VA_ARGS__);                            \
 591 } while (0)
 592 #else
 593 #define DMDEBUG(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
 594 #define DMDEBUG_LIMIT(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
 595 #endif
 596
 597 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 598                           0 : scnprintf(result + sz, maxlen - sz, x))
 599
 600 #define SECTOR_SHIFT 9
 601
 602 /*
 603  * Definitions of return values from target end_io function.
 604  */
 605 #define DM_ENDIO_DONE           0
 606 #define DM_ENDIO_INCOMPLETE     1
 607 #define DM_ENDIO_REQUEUE        2
 608
 609 /*
 610  * Definitions of return values from target map function.
 611  */
 612 #define DM_MAPIO_SUBMITTED      0
 613 #define DM_MAPIO_REMAPPED       1
 614 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 615 #define DM_MAPIO_DELAY_REQUEUE  3
 616 #define DM_MAPIO_KILL           4
 617
 618 #define dm_sector_div64(x, y)( \
 619 { \
 620         u64 _res; \
 621         (x) = div64_u64_rem(x, y, &_res); \
 622         _res; \
 623 } \
 624 )
 625
 626 /*
 627  * Ceiling(n / sz)
 628  */
 629 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 630
 631 #define dm_sector_div_up(n, sz) ( \
 632 { \
 633         sector_t _r = ((n) + (sz) - 1); \
 634         sector_div(_r, (sz)); \
 635         _r; \
 636 } \
 637 )
 638
 639 /*
 640  * ceiling(n / size) * size
 641  */
 642 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 643
 644 #define dm_array_too_big(fixed, obj, num) \
 645         ((num) > (UINT_MAX - (fixed)) / (obj))
 646
 647 /*
 648  * Sector offset taken relative to the start of the target instead of
 649  * relative to the start of the device.
 650  */
 651 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 652
 653 static inline sector_t to_sector(unsigned long n)
 654 {
 655         return (n >> SECTOR_SHIFT);
 656 }
 657
 658 static inline unsigned long to_bytes(sector_t n)
 659 {
 660         return (n << SECTOR_SHIFT);
 661 }
 662
 663 #endif  /* _LINUX_DEVICE_MAPPER_H */