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/ratelimit.h>
  14
  15 struct dm_dev;
  16 struct dm_target;
  17 struct dm_table;
  18 struct mapped_device;
  19 struct bio_vec;
  20
  21 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  22
  23 union map_info {
  24         void *ptr;
  25         unsigned long long ll;
  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
  52 /*
  53  * Returns:
  54  * < 0 : error (currently ignored)
  55  * 0   : ended successfully
  56  * 1   : for some reason the io has still not completed (eg,
  57  *       multipath target might want to requeue a failed io).
  58  * 2   : The target wants to push back the io
  59  */
  60 typedef int (*dm_endio_fn) (struct dm_target *ti,
  61                             struct bio *bio, int error);
  62 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  63                                     struct request *clone, int error,
  64                                     union map_info *map_context);
  65
  66 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  67 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  68 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  69 typedef void (*dm_resume_fn) (struct dm_target *ti);
  70
  71 typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  72                               unsigned status_flags, char *result, unsigned maxlen);
  73
  74 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  75
  76 typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
  77                             unsigned long arg);
  78
  79 typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
  80                             struct bio_vec *biovec, int max_size);
  81
  82 /*
  83  * These iteration functions are typically used to check (and combine)
  84  * properties of underlying devices.
  85  * E.g. Does at least one underlying device support flush?
  86  *      Does any underlying device not support WRITE_SAME?
  87  *
  88  * The callout function is called once for each contiguous section of
  89  * an underlying device.  State can be maintained in *data.
  90  * Return non-zero to stop iterating through any further devices.
  91  */
  92 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
  93                                            struct dm_dev *dev,
  94                                            sector_t start, sector_t len,
  95                                            void *data);
  96
  97 /*
  98  * This function must iterate through each section of device used by the
  99  * target until it encounters a non-zero return code, which it then returns.
 100  * Returns zero if no callout returned non-zero.
 101  */
 102 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
 103                                       iterate_devices_callout_fn fn,
 104                                       void *data);
 105
 106 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
 107                                 struct queue_limits *limits);
 108
 109 /*
 110  * Returns:
 111  *    0: The target can handle the next I/O immediately.
 112  *    1: The target can't handle the next I/O immediately.
 113  */
 114 typedef int (*dm_busy_fn) (struct dm_target *ti);
 115
 116 void dm_error(const char *message);
 117
 118 /*
 119  * Combine device limits.
 120  */
 121 int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 122                          sector_t start, sector_t len, void *data);
 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_endio_fn end_io;
 152         dm_request_endio_fn rq_end_io;
 153         dm_presuspend_fn presuspend;
 154         dm_postsuspend_fn postsuspend;
 155         dm_preresume_fn preresume;
 156         dm_resume_fn resume;
 157         dm_status_fn status;
 158         dm_message_fn message;
 159         dm_ioctl_fn ioctl;
 160         dm_merge_fn merge;
 161         dm_busy_fn busy;
 162         dm_iterate_devices_fn iterate_devices;
 163         dm_io_hints_fn io_hints;
 164
 165         /* For internal device-mapper use. */
 166         struct list_head list;
 167 };
 168
 169 /*
 170  * Target features
 171  */
 172
 173 /*
 174  * Any table that contains an instance of this target must have only one.
 175  */
 176 #define DM_TARGET_SINGLETON             0x00000001
 177 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
 178
 179 /*
 180  * Indicates that a target does not support read-only devices.
 181  */
 182 #define DM_TARGET_ALWAYS_WRITEABLE      0x00000002
 183 #define dm_target_always_writeable(type) \
 184                 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
 185
 186 /*
 187  * Any device that contains a table with an instance of this target may never
 188  * have tables containing any different target type.
 189  */
 190 #define DM_TARGET_IMMUTABLE             0x00000004
 191 #define dm_target_is_immutable(type)    ((type)->features & DM_TARGET_IMMUTABLE)
 192
 193 /*
 194  * Some targets need to be sent the same WRITE bio severals times so
 195  * that they can send copies of it to different devices.  This function
 196  * examines any supplied bio and returns the number of copies of it the
 197  * target requires.
 198  */
 199 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
 200
 201 struct dm_target {
 202         struct dm_table *table;
 203         struct target_type *type;
 204
 205         /* target limits */
 206         sector_t begin;
 207         sector_t len;
 208
 209         /* If non-zero, maximum size of I/O submitted to a target. */
 210         uint32_t max_io_len;
 211
 212         /*
 213          * A number of zero-length barrier bios that will be submitted
 214          * to the target for the purpose of flushing cache.
 215          *
 216          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 217          * It is a responsibility of the target driver to remap these bios
 218          * to the real underlying devices.
 219          */
 220         unsigned num_flush_bios;
 221
 222         /*
 223          * The number of discard bios that will be submitted to the target.
 224          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 225          */
 226         unsigned num_discard_bios;
 227
 228         /*
 229          * The number of WRITE SAME bios that will be submitted to the target.
 230          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 231          */
 232         unsigned num_write_same_bios;
 233
 234         /*
 235          * The minimum number of extra bytes allocated in each bio for the
 236          * target to use.  dm_per_bio_data returns the data location.
 237          */
 238         unsigned per_bio_data_size;
 239
 240         /*
 241          * If defined, this function is called to find out how many
 242          * duplicate bios should be sent to the target when writing
 243          * data.
 244          */
 245         dm_num_write_bios_fn num_write_bios;
 246
 247         /* target specific data */
 248         void *private;
 249
 250         /* Used to provide an error string from the ctr */
 251         char *error;
 252
 253         /*
 254          * Set if this target needs to receive flushes regardless of
 255          * whether or not its underlying devices have support.
 256          */
 257         bool flush_supported:1;
 258
 259         /*
 260          * Set if this target needs to receive discards regardless of
 261          * whether or not its underlying devices have support.
 262          */
 263         bool discards_supported:1;
 264
 265         /*
 266          * Set if the target required discard bios to be split
 267          * on max_io_len boundary.
 268          */
 269         bool split_discard_bios:1;
 270
 271         /*
 272          * Set if this target does not return zeroes on discarded blocks.
 273          */
 274         bool discard_zeroes_data_unsupported:1;
 275 };
 276
 277 /* Each target can link one of these into the table */
 278 struct dm_target_callbacks {
 279         struct list_head list;
 280         int (*congested_fn) (struct dm_target_callbacks *, int);
 281 };
 282
 283 /*
 284  * For bio-based dm.
 285  * One of these is allocated for each bio.
 286  * This structure shouldn't be touched directly by target drivers.
 287  * It is here so that we can inline dm_per_bio_data and
 288  * dm_bio_from_per_bio_data
 289  */
 290 struct dm_target_io {
 291         struct dm_io *io;
 292         struct dm_target *ti;
 293         union map_info info;
 294         unsigned target_bio_nr;
 295         struct bio clone;
 296 };
 297
 298 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
 299 {
 300         return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
 301 }
 302
 303 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
 304 {
 305         return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
 306 }
 307
 308 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
 309 {
 310         return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
 311 }
 312
 313 int dm_register_target(struct target_type *t);
 314 void dm_unregister_target(struct target_type *t);
 315
 316 /*
 317  * Target argument parsing.
 318  */
 319 struct dm_arg_set {
 320         unsigned argc;
 321         char **argv;
 322 };
 323
 324 /*
 325  * The minimum and maximum value of a numeric argument, together with
 326  * the error message to use if the number is found to be outside that range.
 327  */
 328 struct dm_arg {
 329         unsigned min;
 330         unsigned max;
 331         char *error;
 332 };
 333
 334 /*
 335  * Validate the next argument, either returning it as *value or, if invalid,
 336  * returning -EINVAL and setting *error.
 337  */
 338 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 339                 unsigned *value, char **error);
 340
 341 /*
 342  * Process the next argument as the start of a group containing between
 343  * arg->min and arg->max further arguments. Either return the size as
 344  * *num_args or, if invalid, return -EINVAL and set *error.
 345  */
 346 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 347                       unsigned *num_args, char **error);
 348
 349 /*
 350  * Return the current argument and shift to the next.
 351  */
 352 const char *dm_shift_arg(struct dm_arg_set *as);
 353
 354 /*
 355  * Move through num_args arguments.
 356  */
 357 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 358
 359 /*-----------------------------------------------------------------
 360  * Functions for creating and manipulating mapped devices.
 361  * Drop the reference with dm_put when you finish with the object.
 362  *---------------------------------------------------------------*/
 363
 364 /*
 365  * DM_ANY_MINOR chooses the next available minor number.
 366  */
 367 #define DM_ANY_MINOR (-1)
 368 int dm_create(int minor, struct mapped_device **md);
 369
 370 /*
 371  * Reference counting for md.
 372  */
 373 struct mapped_device *dm_get_md(dev_t dev);
 374 void dm_get(struct mapped_device *md);
 375 void dm_put(struct mapped_device *md);
 376
 377 /*
 378  * An arbitrary pointer may be stored alongside a mapped device.
 379  */
 380 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 381 void *dm_get_mdptr(struct mapped_device *md);
 382
 383 /*
 384  * A device can still be used while suspended, but I/O is deferred.
 385  */
 386 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 387 int dm_resume(struct mapped_device *md);
 388
 389 /*
 390  * Event functions.
 391  */
 392 uint32_t dm_get_event_nr(struct mapped_device *md);
 393 int dm_wait_event(struct mapped_device *md, int event_nr);
 394 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 395 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 396
 397 /*
 398  * Info functions.
 399  */
 400 const char *dm_device_name(struct mapped_device *md);
 401 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 402 struct gendisk *dm_disk(struct mapped_device *md);
 403 int dm_suspended(struct dm_target *ti);
 404 int dm_noflush_suspending(struct dm_target *ti);
 405 union map_info *dm_get_mapinfo(struct bio *bio);
 406 union map_info *dm_get_rq_mapinfo(struct request *rq);
 407
 408 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
 409
 410 /*
 411  * Geometry functions.
 412  */
 413 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 414 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 415
 416 /*-----------------------------------------------------------------
 417  * Functions for manipulating device-mapper tables.
 418  *---------------------------------------------------------------*/
 419
 420 /*
 421  * First create an empty table.
 422  */
 423 int dm_table_create(struct dm_table **result, fmode_t mode,
 424                     unsigned num_targets, struct mapped_device *md);
 425
 426 /*
 427  * Then call this once for each target.
 428  */
 429 int dm_table_add_target(struct dm_table *t, const char *type,
 430                         sector_t start, sector_t len, char *params);
 431
 432 /*
 433  * Target_ctr should call this if it needs to add any callbacks.
 434  */
 435 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 436
 437 /*
 438  * Finally call this to make the table ready for use.
 439  */
 440 int dm_table_complete(struct dm_table *t);
 441
 442 /*
 443  * Target may require that it is never sent I/O larger than len.
 444  */
 445 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 446
 447 /*
 448  * Table reference counting.
 449  */
 450 struct dm_table *dm_get_live_table(struct mapped_device *md);
 451 void dm_table_get(struct dm_table *t);
 452 void dm_table_put(struct dm_table *t);
 453
 454 /*
 455  * Queries
 456  */
 457 sector_t dm_table_get_size(struct dm_table *t);
 458 unsigned int dm_table_get_num_targets(struct dm_table *t);
 459 fmode_t dm_table_get_mode(struct dm_table *t);
 460 struct mapped_device *dm_table_get_md(struct dm_table *t);
 461
 462 /*
 463  * Trigger an event.
 464  */
 465 void dm_table_event(struct dm_table *t);
 466
 467 /*
 468  * The device must be suspended before calling this method.
 469  * Returns the previous table, which the caller must destroy.
 470  */
 471 struct dm_table *dm_swap_table(struct mapped_device *md,
 472                                struct dm_table *t);
 473
 474 /*
 475  * A wrapper around vmalloc.
 476  */
 477 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 478
 479 /*-----------------------------------------------------------------
 480  * Macros.
 481  *---------------------------------------------------------------*/
 482 #define DM_NAME "device-mapper"
 483
 484 #ifdef CONFIG_PRINTK
 485 extern struct ratelimit_state dm_ratelimit_state;
 486
 487 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 488 #else
 489 #define dm_ratelimit()  0
 490 #endif
 491
 492 #define DMCRIT(f, arg...) \
 493         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 494
 495 #define DMERR(f, arg...) \
 496         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 497 #define DMERR_LIMIT(f, arg...) \
 498         do { \
 499                 if (dm_ratelimit())     \
 500                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 501                                f "\n", ## arg); \
 502         } while (0)
 503
 504 #define DMWARN(f, arg...) \
 505         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 506 #define DMWARN_LIMIT(f, arg...) \
 507         do { \
 508                 if (dm_ratelimit())     \
 509                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 510                                f "\n", ## arg); \
 511         } while (0)
 512
 513 #define DMINFO(f, arg...) \
 514         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 515 #define DMINFO_LIMIT(f, arg...) \
 516         do { \
 517                 if (dm_ratelimit())     \
 518                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 519                                "\n", ## arg); \
 520         } while (0)
 521
 522 #ifdef CONFIG_DM_DEBUG
 523 #  define DMDEBUG(f, arg...) \
 524         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 525 #  define DMDEBUG_LIMIT(f, arg...) \
 526         do { \
 527                 if (dm_ratelimit())     \
 528                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 529                                "\n", ## arg); \
 530         } while (0)
 531 #else
 532 #  define DMDEBUG(f, arg...) do {} while (0)
 533 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 534 #endif
 535
 536 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 537                           0 : scnprintf(result + sz, maxlen - sz, x))
 538
 539 #define SECTOR_SHIFT 9
 540
 541 /*
 542  * Definitions of return values from target end_io function.
 543  */
 544 #define DM_ENDIO_INCOMPLETE     1
 545 #define DM_ENDIO_REQUEUE        2
 546
 547 /*
 548  * Definitions of return values from target map function.
 549  */
 550 #define DM_MAPIO_SUBMITTED      0
 551 #define DM_MAPIO_REMAPPED       1
 552 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 553
 554 /*
 555  * Ceiling(n / sz)
 556  */
 557 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 558
 559 #define dm_sector_div_up(n, sz) ( \
 560 { \
 561         sector_t _r = ((n) + (sz) - 1); \
 562         sector_div(_r, (sz)); \
 563         _r; \
 564 } \
 565 )
 566
 567 /*
 568  * ceiling(n / size) * size
 569  */
 570 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 571
 572 #define dm_array_too_big(fixed, obj, num) \
 573         ((num) > (UINT_MAX - (fixed)) / (obj))
 574
 575 /*
 576  * Sector offset taken relative to the start of the target instead of
 577  * relative to the start of the device.
 578  */
 579 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 580
 581 static inline sector_t to_sector(unsigned long n)
 582 {
 583         return (n >> SECTOR_SHIFT);
 584 }
 585
 586 static inline unsigned long to_bytes(sector_t n)
 587 {
 588         return (n << SECTOR_SHIFT);
 589 }
 590
 591 /*-----------------------------------------------------------------
 592  * Helper for block layer and dm core operations
 593  *---------------------------------------------------------------*/
 594 void dm_dispatch_request(struct request *rq);
 595 void dm_requeue_unmapped_request(struct request *rq);
 596 void dm_kill_unmapped_request(struct request *rq, int error);
 597 int dm_underlying_device_busy(struct request_queue *q);
 598
 599 #endif  /* _LINUX_DEVICE_MAPPER_H */