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 number of WRITE ZEROES bios that will be submitted to the target.
 259          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 260          */
 261         unsigned num_write_zeroes_bios;
 262
 263         /*
 264          * The minimum number of extra bytes allocated in each io for the
 265          * target to use.
 266          */
 267         unsigned per_io_data_size;
 268
 269         /*
 270          * If defined, this function is called to find out how many
 271          * duplicate bios should be sent to the target when writing
 272          * data.
 273          */
 274         dm_num_write_bios_fn num_write_bios;
 275
 276         /* target specific data */
 277         void *private;
 278
 279         /* Used to provide an error string from the ctr */
 280         char *error;
 281
 282         /*
 283          * Set if this target needs to receive flushes regardless of
 284          * whether or not its underlying devices have support.
 285          */
 286         bool flush_supported:1;
 287
 288         /*
 289          * Set if this target needs to receive discards regardless of
 290          * whether or not its underlying devices have support.
 291          */
 292         bool discards_supported:1;
 293
 294         /*
 295          * Set if the target required discard bios to be split
 296          * on max_io_len boundary.
 297          */
 298         bool split_discard_bios:1;
 299 };
 300
 301 /* Each target can link one of these into the table */
 302 struct dm_target_callbacks {
 303         struct list_head list;
 304         int (*congested_fn) (struct dm_target_callbacks *, int);
 305 };
 306
 307 /*
 308  * For bio-based dm.
 309  * One of these is allocated for each bio.
 310  * This structure shouldn't be touched directly by target drivers.
 311  * It is here so that we can inline dm_per_bio_data and
 312  * dm_bio_from_per_bio_data
 313  */
 314 struct dm_target_io {
 315         struct dm_io *io;
 316         struct dm_target *ti;
 317         unsigned target_bio_nr;
 318         unsigned *len_ptr;
 319         struct bio clone;
 320 };
 321
 322 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
 323 {
 324         return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
 325 }
 326
 327 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
 328 {
 329         return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
 330 }
 331
 332 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
 333 {
 334         return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
 335 }
 336
 337 int dm_register_target(struct target_type *t);
 338 void dm_unregister_target(struct target_type *t);
 339
 340 /*
 341  * Target argument parsing.
 342  */
 343 struct dm_arg_set {
 344         unsigned argc;
 345         char **argv;
 346 };
 347
 348 /*
 349  * The minimum and maximum value of a numeric argument, together with
 350  * the error message to use if the number is found to be outside that range.
 351  */
 352 struct dm_arg {
 353         unsigned min;
 354         unsigned max;
 355         char *error;
 356 };
 357
 358 /*
 359  * Validate the next argument, either returning it as *value or, if invalid,
 360  * returning -EINVAL and setting *error.
 361  */
 362 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 363                 unsigned *value, char **error);
 364
 365 /*
 366  * Process the next argument as the start of a group containing between
 367  * arg->min and arg->max further arguments. Either return the size as
 368  * *num_args or, if invalid, return -EINVAL and set *error.
 369  */
 370 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 371                       unsigned *num_args, char **error);
 372
 373 /*
 374  * Return the current argument and shift to the next.
 375  */
 376 const char *dm_shift_arg(struct dm_arg_set *as);
 377
 378 /*
 379  * Move through num_args arguments.
 380  */
 381 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 382
 383 /*-----------------------------------------------------------------
 384  * Functions for creating and manipulating mapped devices.
 385  * Drop the reference with dm_put when you finish with the object.
 386  *---------------------------------------------------------------*/
 387
 388 /*
 389  * DM_ANY_MINOR chooses the next available minor number.
 390  */
 391 #define DM_ANY_MINOR (-1)
 392 int dm_create(int minor, struct mapped_device **md);
 393
 394 /*
 395  * Reference counting for md.
 396  */
 397 struct mapped_device *dm_get_md(dev_t dev);
 398 void dm_get(struct mapped_device *md);
 399 int dm_hold(struct mapped_device *md);
 400 void dm_put(struct mapped_device *md);
 401
 402 /*
 403  * An arbitrary pointer may be stored alongside a mapped device.
 404  */
 405 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 406 void *dm_get_mdptr(struct mapped_device *md);
 407
 408 /*
 409  * A device can still be used while suspended, but I/O is deferred.
 410  */
 411 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 412 int dm_resume(struct mapped_device *md);
 413
 414 /*
 415  * Event functions.
 416  */
 417 uint32_t dm_get_event_nr(struct mapped_device *md);
 418 int dm_wait_event(struct mapped_device *md, int event_nr);
 419 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 420 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 421
 422 /*
 423  * Info functions.
 424  */
 425 const char *dm_device_name(struct mapped_device *md);
 426 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 427 struct gendisk *dm_disk(struct mapped_device *md);
 428 int dm_suspended(struct dm_target *ti);
 429 int dm_noflush_suspending(struct dm_target *ti);
 430 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
 431 union map_info *dm_get_rq_mapinfo(struct request *rq);
 432
 433 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
 434
 435 /*
 436  * Geometry functions.
 437  */
 438 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 439 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 440
 441 /*-----------------------------------------------------------------
 442  * Functions for manipulating device-mapper tables.
 443  *---------------------------------------------------------------*/
 444
 445 /*
 446  * First create an empty table.
 447  */
 448 int dm_table_create(struct dm_table **result, fmode_t mode,
 449                     unsigned num_targets, struct mapped_device *md);
 450
 451 /*
 452  * Then call this once for each target.
 453  */
 454 int dm_table_add_target(struct dm_table *t, const char *type,
 455                         sector_t start, sector_t len, char *params);
 456
 457 /*
 458  * Target_ctr should call this if it needs to add any callbacks.
 459  */
 460 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 461
 462 /*
 463  * Target can use this to set the table's type.
 464  * Can only ever be called from a target's ctr.
 465  * Useful for "hybrid" target (supports both bio-based
 466  * and request-based).
 467  */
 468 void dm_table_set_type(struct dm_table *t, unsigned type);
 469
 470 /*
 471  * Finally call this to make the table ready for use.
 472  */
 473 int dm_table_complete(struct dm_table *t);
 474
 475 /*
 476  * Target may require that it is never sent I/O larger than len.
 477  */
 478 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 479
 480 /*
 481  * Table reference counting.
 482  */
 483 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
 484 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
 485 void dm_sync_table(struct mapped_device *md);
 486
 487 /*
 488  * Queries
 489  */
 490 sector_t dm_table_get_size(struct dm_table *t);
 491 unsigned int dm_table_get_num_targets(struct dm_table *t);
 492 fmode_t dm_table_get_mode(struct dm_table *t);
 493 struct mapped_device *dm_table_get_md(struct dm_table *t);
 494
 495 /*
 496  * Trigger an event.
 497  */
 498 void dm_table_event(struct dm_table *t);
 499
 500 /*
 501  * Run the queue for request-based targets.
 502  */
 503 void dm_table_run_md_queue_async(struct dm_table *t);
 504
 505 /*
 506  * The device must be suspended before calling this method.
 507  * Returns the previous table, which the caller must destroy.
 508  */
 509 struct dm_table *dm_swap_table(struct mapped_device *md,
 510                                struct dm_table *t);
 511
 512 /*
 513  * A wrapper around vmalloc.
 514  */
 515 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 516
 517 /*-----------------------------------------------------------------
 518  * Macros.
 519  *---------------------------------------------------------------*/
 520 #define DM_NAME "device-mapper"
 521
 522 #ifdef CONFIG_PRINTK
 523 extern struct ratelimit_state dm_ratelimit_state;
 524
 525 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 526 #else
 527 #define dm_ratelimit()  0
 528 #endif
 529
 530 #define DMCRIT(f, arg...) \
 531         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 532
 533 #define DMERR(f, arg...) \
 534         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 535 #define DMERR_LIMIT(f, arg...) \
 536         do { \
 537                 if (dm_ratelimit())     \
 538                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 539                                f "\n", ## arg); \
 540         } while (0)
 541
 542 #define DMWARN(f, arg...) \
 543         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 544 #define DMWARN_LIMIT(f, arg...) \
 545         do { \
 546                 if (dm_ratelimit())     \
 547                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 548                                f "\n", ## arg); \
 549         } while (0)
 550
 551 #define DMINFO(f, arg...) \
 552         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 553 #define DMINFO_LIMIT(f, arg...) \
 554         do { \
 555                 if (dm_ratelimit())     \
 556                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 557                                "\n", ## arg); \
 558         } while (0)
 559
 560 #ifdef CONFIG_DM_DEBUG
 561 #  define DMDEBUG(f, arg...) \
 562         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 563 #  define DMDEBUG_LIMIT(f, arg...) \
 564         do { \
 565                 if (dm_ratelimit())     \
 566                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 567                                "\n", ## arg); \
 568         } while (0)
 569 #else
 570 #  define DMDEBUG(f, arg...) do {} while (0)
 571 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 572 #endif
 573
 574 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 575                           0 : scnprintf(result + sz, maxlen - sz, x))
 576
 577 #define SECTOR_SHIFT 9
 578
 579 /*
 580  * Definitions of return values from target end_io function.
 581  */
 582 #define DM_ENDIO_INCOMPLETE     1
 583 #define DM_ENDIO_REQUEUE        2
 584
 585 /*
 586  * Definitions of return values from target map function.
 587  */
 588 #define DM_MAPIO_SUBMITTED      0
 589 #define DM_MAPIO_REMAPPED       1
 590 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 591 #define DM_MAPIO_DELAY_REQUEUE  3
 592
 593 #define dm_sector_div64(x, y)( \
 594 { \
 595         u64 _res; \
 596         (x) = div64_u64_rem(x, y, &_res); \
 597         _res; \
 598 } \
 599 )
 600
 601 /*
 602  * Ceiling(n / sz)
 603  */
 604 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 605
 606 #define dm_sector_div_up(n, sz) ( \
 607 { \
 608         sector_t _r = ((n) + (sz) - 1); \
 609         sector_div(_r, (sz)); \
 610         _r; \
 611 } \
 612 )
 613
 614 /*
 615  * ceiling(n / size) * size
 616  */
 617 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 618
 619 #define dm_array_too_big(fixed, obj, num) \
 620         ((num) > (UINT_MAX - (fixed)) / (obj))
 621
 622 /*
 623  * Sector offset taken relative to the start of the target instead of
 624  * relative to the start of the device.
 625  */
 626 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 627
 628 static inline sector_t to_sector(unsigned long n)
 629 {
 630         return (n >> SECTOR_SHIFT);
 631 }
 632
 633 static inline unsigned long to_bytes(sector_t n)
 634 {
 635         return (n << SECTOR_SHIFT);
 636 }
 637
 638 #endif  /* _LINUX_DEVICE_MAPPER_H */