root/include/linux/device-mapper.h

INCLUDED FROM

DEFINITIONS

1. to_sector
2. to_bytes

   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/dm-ioctl.h>
  14 #include <linux/math64.h>
  15 #include <linux/ratelimit.h>
  16 
  17 struct dm_dev;
  18 struct dm_target;
  19 struct dm_table;
  20 struct mapped_device;
  21 struct bio_vec;
  22 
  23 /*
  24  * Type of table, mapped_device's mempool and request_queue
  25  */
  26 enum dm_queue_mode {
  27         DM_TYPE_NONE             = 0,
  28         DM_TYPE_BIO_BASED        = 1,
  29         DM_TYPE_REQUEST_BASED    = 2,
  30         DM_TYPE_DAX_BIO_BASED    = 3,
  31         DM_TYPE_NVME_BIO_BASED   = 4,
  32 };
  33 
  34 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  35 
  36 union map_info {
  37         void *ptr;
  38 };
  39 
  40 /*
  41  * In the constructor the target parameter will already have the
  42  * table, type, begin and len fields filled in.
  43  */
  44 typedef int (*dm_ctr_fn) (struct dm_target *target,
  45                           unsigned int argc, char **argv);
  46 
  47 /*
  48  * The destructor doesn't need to free the dm_target, just
  49  * anything hidden ti->private.
  50  */
  51 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  52 
  53 /*
  54  * The map function must return:
  55  * < 0: error
  56  * = 0: The target will handle the io by resubmitting it later
  57  * = 1: simple remap complete
  58  * = 2: The target wants to push back the io
  59  */
  60 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio);
  61 typedef int (*dm_clone_and_map_request_fn) (struct dm_target *ti,
  62                                             struct request *rq,
  63                                             union map_info *map_context,
  64                                             struct request **clone);
  65 typedef void (*dm_release_clone_request_fn) (struct request *clone,
  66                                              union map_info *map_context);
  67 
  68 /*
  69  * Returns:
  70  * < 0 : error (currently ignored)
  71  * 0   : ended successfully
  72  * 1   : for some reason the io has still not completed (eg,
  73  *       multipath target might want to requeue a failed io).
  74  * 2   : The target wants to push back the io
  75  */
  76 typedef int (*dm_endio_fn) (struct dm_target *ti,
  77                             struct bio *bio, blk_status_t *error);
  78 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  79                                     struct request *clone, blk_status_t error,
  80                                     union map_info *map_context);
  81 
  82 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  83 typedef void (*dm_presuspend_undo_fn) (struct dm_target *ti);
  84 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  85 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  86 typedef void (*dm_resume_fn) (struct dm_target *ti);
  87 
  88 typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  89                               unsigned status_flags, char *result, unsigned maxlen);
  90 
  91 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv,
  92                               char *result, unsigned maxlen);
  93 
  94 typedef int (*dm_prepare_ioctl_fn) (struct dm_target *ti, struct block_device **bdev);
  95 
  96 typedef int (*dm_report_zones_fn) (struct dm_target *ti, sector_t sector,
  97                                    struct blk_zone *zones,
  98                                    unsigned int *nr_zones);
  99 
 100 /*
 101  * These iteration functions are typically used to check (and combine)
 102  * properties of underlying devices.
 103  * E.g. Does at least one underlying device support flush?
 104  *      Does any underlying device not support WRITE_SAME?
 105  *
 106  * The callout function is called once for each contiguous section of
 107  * an underlying device.  State can be maintained in *data.
 108  * Return non-zero to stop iterating through any further devices.
 109  */
 110 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
 111                                            struct dm_dev *dev,
 112                                            sector_t start, sector_t len,
 113                                            void *data);
 114 
 115 /*
 116  * This function must iterate through each section of device used by the
 117  * target until it encounters a non-zero return code, which it then returns.
 118  * Returns zero if no callout returned non-zero.
 119  */
 120 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
 121                                       iterate_devices_callout_fn fn,
 122                                       void *data);
 123 
 124 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
 125                                 struct queue_limits *limits);
 126 
 127 /*
 128  * Returns:
 129  *    0: The target can handle the next I/O immediately.
 130  *    1: The target can't handle the next I/O immediately.
 131  */
 132 typedef int (*dm_busy_fn) (struct dm_target *ti);
 133 
 134 /*
 135  * Returns:
 136  *  < 0 : error
 137  * >= 0 : the number of bytes accessible at the address
 138  */
 139 typedef long (*dm_dax_direct_access_fn) (struct dm_target *ti, pgoff_t pgoff,
 140                 long nr_pages, void **kaddr, pfn_t *pfn);
 141 typedef size_t (*dm_dax_copy_iter_fn)(struct dm_target *ti, pgoff_t pgoff,
 142                 void *addr, size_t bytes, struct iov_iter *i);
 143 #define PAGE_SECTORS (PAGE_SIZE / 512)
 144 
 145 void dm_error(const char *message);
 146 
 147 struct dm_dev {
 148         struct block_device *bdev;
 149         struct dax_device *dax_dev;
 150         fmode_t mode;
 151         char name[16];
 152 };
 153 
 154 dev_t dm_get_dev_t(const char *path);
 155 
 156 /*
 157  * Constructors should call these functions to ensure destination devices
 158  * are opened/closed correctly.
 159  */
 160 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 161                   struct dm_dev **result);
 162 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 163 
 164 /*
 165  * Information about a target type
 166  */
 167 
 168 struct target_type {
 169         uint64_t features;
 170         const char *name;
 171         struct module *module;
 172         unsigned version[3];
 173         dm_ctr_fn ctr;
 174         dm_dtr_fn dtr;
 175         dm_map_fn map;
 176         dm_clone_and_map_request_fn clone_and_map_rq;
 177         dm_release_clone_request_fn release_clone_rq;
 178         dm_endio_fn end_io;
 179         dm_request_endio_fn rq_end_io;
 180         dm_presuspend_fn presuspend;
 181         dm_presuspend_undo_fn presuspend_undo;
 182         dm_postsuspend_fn postsuspend;
 183         dm_preresume_fn preresume;
 184         dm_resume_fn resume;
 185         dm_status_fn status;
 186         dm_message_fn message;
 187         dm_prepare_ioctl_fn prepare_ioctl;
 188 #ifdef CONFIG_BLK_DEV_ZONED
 189         dm_report_zones_fn report_zones;
 190 #endif
 191         dm_busy_fn busy;
 192         dm_iterate_devices_fn iterate_devices;
 193         dm_io_hints_fn io_hints;
 194         dm_dax_direct_access_fn direct_access;
 195         dm_dax_copy_iter_fn dax_copy_from_iter;
 196         dm_dax_copy_iter_fn dax_copy_to_iter;
 197 
 198         /* For internal device-mapper use. */
 199         struct list_head list;
 200 };
 201 
 202 /*
 203  * Target features
 204  */
 205 
 206 /*
 207  * Any table that contains an instance of this target must have only one.
 208  */
 209 #define DM_TARGET_SINGLETON             0x00000001
 210 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
 211 
 212 /*
 213  * Indicates that a target does not support read-only devices.
 214  */
 215 #define DM_TARGET_ALWAYS_WRITEABLE      0x00000002
 216 #define dm_target_always_writeable(type) \
 217                 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
 218 
 219 /*
 220  * Any device that contains a table with an instance of this target may never
 221  * have tables containing any different target type.
 222  */
 223 #define DM_TARGET_IMMUTABLE             0x00000004
 224 #define dm_target_is_immutable(type)    ((type)->features & DM_TARGET_IMMUTABLE)
 225 
 226 /*
 227  * Indicates that a target may replace any target; even immutable targets.
 228  * .map, .map_rq, .clone_and_map_rq and .release_clone_rq are all defined.
 229  */
 230 #define DM_TARGET_WILDCARD              0x00000008
 231 #define dm_target_is_wildcard(type)     ((type)->features & DM_TARGET_WILDCARD)
 232 
 233 /*
 234  * A target implements own bio data integrity.
 235  */
 236 #define DM_TARGET_INTEGRITY             0x00000010
 237 #define dm_target_has_integrity(type)   ((type)->features & DM_TARGET_INTEGRITY)
 238 
 239 /*
 240  * A target passes integrity data to the lower device.
 241  */
 242 #define DM_TARGET_PASSES_INTEGRITY      0x00000020
 243 #define dm_target_passes_integrity(type) ((type)->features & DM_TARGET_PASSES_INTEGRITY)
 244 
 245 /*
 246  * Indicates that a target supports host-managed zoned block devices.
 247  */
 248 #define DM_TARGET_ZONED_HM              0x00000040
 249 #define dm_target_supports_zoned_hm(type) ((type)->features & DM_TARGET_ZONED_HM)
 250 
 251 struct dm_target {
 252         struct dm_table *table;
 253         struct target_type *type;
 254 
 255         /* target limits */
 256         sector_t begin;
 257         sector_t len;
 258 
 259         /* If non-zero, maximum size of I/O submitted to a target. */
 260         uint32_t max_io_len;
 261 
 262         /*
 263          * A number of zero-length barrier bios that will be submitted
 264          * to the target for the purpose of flushing cache.
 265          *
 266          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 267          * It is a responsibility of the target driver to remap these bios
 268          * to the real underlying devices.
 269          */
 270         unsigned num_flush_bios;
 271 
 272         /*
 273          * The number of discard bios that will be submitted to the target.
 274          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 275          */
 276         unsigned num_discard_bios;
 277 
 278         /*
 279          * The number of secure erase bios that will be submitted to the target.
 280          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 281          */
 282         unsigned num_secure_erase_bios;
 283 
 284         /*
 285          * The number of WRITE SAME bios that will be submitted to the target.
 286          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 287          */
 288         unsigned num_write_same_bios;
 289 
 290         /*
 291          * The number of WRITE ZEROES bios that will be submitted to the target.
 292          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 293          */
 294         unsigned num_write_zeroes_bios;
 295 
 296         /*
 297          * The minimum number of extra bytes allocated in each io for the
 298          * target to use.
 299          */
 300         unsigned per_io_data_size;
 301 
 302         /* target specific data */
 303         void *private;
 304 
 305         /* Used to provide an error string from the ctr */
 306         char *error;
 307 
 308         /*
 309          * Set if this target needs to receive flushes regardless of
 310          * whether or not its underlying devices have support.
 311          */
 312         bool flush_supported:1;
 313 
 314         /*
 315          * Set if this target needs to receive discards regardless of
 316          * whether or not its underlying devices have support.
 317          */
 318         bool discards_supported:1;
 319 };
 320 
 321 /* Each target can link one of these into the table */
 322 struct dm_target_callbacks {
 323         struct list_head list;
 324         int (*congested_fn) (struct dm_target_callbacks *, int);
 325 };
 326 
 327 void *dm_per_bio_data(struct bio *bio, size_t data_size);
 328 struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size);
 329 unsigned dm_bio_get_target_bio_nr(const struct bio *bio);
 330 
 331 int dm_register_target(struct target_type *t);
 332 void dm_unregister_target(struct target_type *t);
 333 
 334 /*
 335  * Target argument parsing.
 336  */
 337 struct dm_arg_set {
 338         unsigned argc;
 339         char **argv;
 340 };
 341 
 342 /*
 343  * The minimum and maximum value of a numeric argument, together with
 344  * the error message to use if the number is found to be outside that range.
 345  */
 346 struct dm_arg {
 347         unsigned min;
 348         unsigned max;
 349         char *error;
 350 };
 351 
 352 /*
 353  * Validate the next argument, either returning it as *value or, if invalid,
 354  * returning -EINVAL and setting *error.
 355  */
 356 int dm_read_arg(const struct dm_arg *arg, struct dm_arg_set *arg_set,
 357                 unsigned *value, char **error);
 358 
 359 /*
 360  * Process the next argument as the start of a group containing between
 361  * arg->min and arg->max further arguments. Either return the size as
 362  * *num_args or, if invalid, return -EINVAL and set *error.
 363  */
 364 int dm_read_arg_group(const struct dm_arg *arg, struct dm_arg_set *arg_set,
 365                       unsigned *num_args, char **error);
 366 
 367 /*
 368  * Return the current argument and shift to the next.
 369  */
 370 const char *dm_shift_arg(struct dm_arg_set *as);
 371 
 372 /*
 373  * Move through num_args arguments.
 374  */
 375 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 376 
 377 /*-----------------------------------------------------------------
 378  * Functions for creating and manipulating mapped devices.
 379  * Drop the reference with dm_put when you finish with the object.
 380  *---------------------------------------------------------------*/
 381 
 382 /*
 383  * DM_ANY_MINOR chooses the next available minor number.
 384  */
 385 #define DM_ANY_MINOR (-1)
 386 int dm_create(int minor, struct mapped_device **md);
 387 
 388 /*
 389  * Reference counting for md.
 390  */
 391 struct mapped_device *dm_get_md(dev_t dev);
 392 void dm_get(struct mapped_device *md);
 393 int dm_hold(struct mapped_device *md);
 394 void dm_put(struct mapped_device *md);
 395 
 396 /*
 397  * An arbitrary pointer may be stored alongside a mapped device.
 398  */
 399 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 400 void *dm_get_mdptr(struct mapped_device *md);
 401 
 402 /*
 403  * A device can still be used while suspended, but I/O is deferred.
 404  */
 405 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 406 int dm_resume(struct mapped_device *md);
 407 
 408 /*
 409  * Event functions.
 410  */
 411 uint32_t dm_get_event_nr(struct mapped_device *md);
 412 int dm_wait_event(struct mapped_device *md, int event_nr);
 413 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 414 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 415 
 416 /*
 417  * Info functions.
 418  */
 419 const char *dm_device_name(struct mapped_device *md);
 420 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 421 struct gendisk *dm_disk(struct mapped_device *md);
 422 int dm_suspended(struct dm_target *ti);
 423 int dm_noflush_suspending(struct dm_target *ti);
 424 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
 425 void dm_remap_zone_report(struct dm_target *ti, sector_t start,
 426                           struct blk_zone *zones, unsigned int *nr_zones);
 427 union map_info *dm_get_rq_mapinfo(struct request *rq);
 428 
 429 /*
 430  * Device mapper functions to parse and create devices specified by the
 431  * parameter "dm-mod.create="
 432  */
 433 int __init dm_early_create(struct dm_ioctl *dmi,
 434                            struct dm_target_spec **spec_array,
 435                            char **target_params_array);
 436 
 437 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
 438 
 439 /*
 440  * Geometry functions.
 441  */
 442 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 443 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 444 
 445 /*-----------------------------------------------------------------
 446  * Functions for manipulating device-mapper tables.
 447  *---------------------------------------------------------------*/
 448 
 449 /*
 450  * First create an empty table.
 451  */
 452 int dm_table_create(struct dm_table **result, fmode_t mode,
 453                     unsigned num_targets, struct mapped_device *md);
 454 
 455 /*
 456  * Then call this once for each target.
 457  */
 458 int dm_table_add_target(struct dm_table *t, const char *type,
 459                         sector_t start, sector_t len, char *params);
 460 
 461 /*
 462  * Target_ctr should call this if it needs to add any callbacks.
 463  */
 464 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 465 
 466 /*
 467  * Target can use this to set the table's type.
 468  * Can only ever be called from a target's ctr.
 469  * Useful for "hybrid" target (supports both bio-based
 470  * and request-based).
 471  */
 472 void dm_table_set_type(struct dm_table *t, enum dm_queue_mode type);
 473 
 474 /*
 475  * Finally call this to make the table ready for use.
 476  */
 477 int dm_table_complete(struct dm_table *t);
 478 
 479 /*
 480  * Destroy the table when finished.
 481  */
 482 void dm_table_destroy(struct dm_table *t);
 483 
 484 /*
 485  * Target may require that it is never sent I/O larger than len.
 486  */
 487 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 488 
 489 /*
 490  * Table reference counting.
 491  */
 492 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
 493 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
 494 void dm_sync_table(struct mapped_device *md);
 495 
 496 /*
 497  * Queries
 498  */
 499 sector_t dm_table_get_size(struct dm_table *t);
 500 unsigned int dm_table_get_num_targets(struct dm_table *t);
 501 fmode_t dm_table_get_mode(struct dm_table *t);
 502 struct mapped_device *dm_table_get_md(struct dm_table *t);
 503 const char *dm_table_device_name(struct dm_table *t);
 504 
 505 /*
 506  * Trigger an event.
 507  */
 508 void dm_table_event(struct dm_table *t);
 509 
 510 /*
 511  * Run the queue for request-based targets.
 512  */
 513 void dm_table_run_md_queue_async(struct dm_table *t);
 514 
 515 /*
 516  * The device must be suspended before calling this method.
 517  * Returns the previous table, which the caller must destroy.
 518  */
 519 struct dm_table *dm_swap_table(struct mapped_device *md,
 520                                struct dm_table *t);
 521 
 522 /*
 523  * A wrapper around vmalloc.
 524  */
 525 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 526 
 527 /*-----------------------------------------------------------------
 528  * Macros.
 529  *---------------------------------------------------------------*/
 530 #define DM_NAME "device-mapper"
 531 
 532 #define DM_FMT(fmt) DM_NAME ": " DM_MSG_PREFIX ": " fmt "\n"
 533 
 534 #define DMCRIT(fmt, ...) pr_crit(DM_FMT(fmt), ##__VA_ARGS__)
 535 
 536 #define DMERR(fmt, ...) pr_err(DM_FMT(fmt), ##__VA_ARGS__)
 537 #define DMERR_LIMIT(fmt, ...) pr_err_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
 538 #define DMWARN(fmt, ...) pr_warn(DM_FMT(fmt), ##__VA_ARGS__)
 539 #define DMWARN_LIMIT(fmt, ...) pr_warn_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
 540 #define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
 541 #define DMINFO_LIMIT(fmt, ...) pr_info_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
 542 
 543 #ifdef CONFIG_DM_DEBUG
 544 #define DMDEBUG(fmt, ...) printk(KERN_DEBUG DM_FMT(fmt), ##__VA_ARGS__)
 545 #define DMDEBUG_LIMIT(fmt, ...) pr_debug_ratelimited(DM_FMT(fmt), ##__VA_ARGS__)
 546 #else
 547 #define DMDEBUG(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
 548 #define DMDEBUG_LIMIT(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
 549 #endif
 550 
 551 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 552                           0 : scnprintf(result + sz, maxlen - sz, x))
 553 
 554 /*
 555  * Definitions of return values from target end_io function.
 556  */
 557 #define DM_ENDIO_DONE           0
 558 #define DM_ENDIO_INCOMPLETE     1
 559 #define DM_ENDIO_REQUEUE        2
 560 #define DM_ENDIO_DELAY_REQUEUE  3
 561 
 562 /*
 563  * Definitions of return values from target map function.
 564  */
 565 #define DM_MAPIO_SUBMITTED      0
 566 #define DM_MAPIO_REMAPPED       1
 567 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 568 #define DM_MAPIO_DELAY_REQUEUE  DM_ENDIO_DELAY_REQUEUE
 569 #define DM_MAPIO_KILL           4
 570 
 571 #define dm_sector_div64(x, y)( \
 572 { \
 573         u64 _res; \
 574         (x) = div64_u64_rem(x, y, &_res); \
 575         _res; \
 576 } \
 577 )
 578 
 579 /*
 580  * Ceiling(n / sz)
 581  */
 582 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 583 
 584 #define dm_sector_div_up(n, sz) ( \
 585 { \
 586         sector_t _r = ((n) + (sz) - 1); \
 587         sector_div(_r, (sz)); \
 588         _r; \
 589 } \
 590 )
 591 
 592 /*
 593  * ceiling(n / size) * size
 594  */
 595 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 596 
 597 #define dm_array_too_big(fixed, obj, num) \
 598         ((num) > (UINT_MAX - (fixed)) / (obj))
 599 
 600 /*
 601  * Sector offset taken relative to the start of the target instead of
 602  * relative to the start of the device.
 603  */
 604 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 605 
 606 static inline sector_t to_sector(unsigned long long n)
 607 {
 608         return (n >> SECTOR_SHIFT);
 609 }
 610 
 611 static inline unsigned long to_bytes(sector_t n)
 612 {
 613         return (n << SECTOR_SHIFT);
 614 }
 615 
 616 #endif  /* _LINUX_DEVICE_MAPPER_H */