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 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
  83                                            struct dm_dev *dev,
  84                                            sector_t start, sector_t len,
  85                                            void *data);
  86
  87 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
  88                                       iterate_devices_callout_fn fn,
  89                                       void *data);
  90
  91 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
  92                                 struct queue_limits *limits);
  93
  94 /*
  95  * Returns:
  96  *    0: The target can handle the next I/O immediately.
  97  *    1: The target can't handle the next I/O immediately.
  98  */
  99 typedef int (*dm_busy_fn) (struct dm_target *ti);
 100
 101 void dm_error(const char *message);
 102
 103 /*
 104  * Combine device limits.
 105  */
 106 int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 107                          sector_t start, sector_t len, void *data);
 108
 109 struct dm_dev {
 110         struct block_device *bdev;
 111         fmode_t mode;
 112         char name[16];
 113 };
 114
 115 /*
 116  * Constructors should call these functions to ensure destination devices
 117  * are opened/closed correctly.
 118  */
 119 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 120                                                  struct dm_dev **result);
 121 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 122
 123 /*
 124  * Information about a target type
 125  */
 126
 127 struct target_type {
 128         uint64_t features;
 129         const char *name;
 130         struct module *module;
 131         unsigned version[3];
 132         dm_ctr_fn ctr;
 133         dm_dtr_fn dtr;
 134         dm_map_fn map;
 135         dm_map_request_fn map_rq;
 136         dm_endio_fn end_io;
 137         dm_request_endio_fn rq_end_io;
 138         dm_presuspend_fn presuspend;
 139         dm_postsuspend_fn postsuspend;
 140         dm_preresume_fn preresume;
 141         dm_resume_fn resume;
 142         dm_status_fn status;
 143         dm_message_fn message;
 144         dm_ioctl_fn ioctl;
 145         dm_merge_fn merge;
 146         dm_busy_fn busy;
 147         dm_iterate_devices_fn iterate_devices;
 148         dm_io_hints_fn io_hints;
 149
 150         /* For internal device-mapper use. */
 151         struct list_head list;
 152 };
 153
 154 /*
 155  * Target features
 156  */
 157
 158 /*
 159  * Any table that contains an instance of this target must have only one.
 160  */
 161 #define DM_TARGET_SINGLETON             0x00000001
 162 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
 163
 164 /*
 165  * Indicates that a target does not support read-only devices.
 166  */
 167 #define DM_TARGET_ALWAYS_WRITEABLE      0x00000002
 168 #define dm_target_always_writeable(type) \
 169                 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
 170
 171 /*
 172  * Any device that contains a table with an instance of this target may never
 173  * have tables containing any different target type.
 174  */
 175 #define DM_TARGET_IMMUTABLE             0x00000004
 176 #define dm_target_is_immutable(type)    ((type)->features & DM_TARGET_IMMUTABLE)
 177
 178 /*
 179  * Some targets need to be sent the same WRITE bio severals times so
 180  * that they can send copies of it to different devices.  This function
 181  * examines any supplied bio and returns the number of copies of it the
 182  * target requires.
 183  */
 184 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
 185
 186 struct dm_target {
 187         struct dm_table *table;
 188         struct target_type *type;
 189
 190         /* target limits */
 191         sector_t begin;
 192         sector_t len;
 193
 194         /* If non-zero, maximum size of I/O submitted to a target. */
 195         uint32_t max_io_len;
 196
 197         /*
 198          * A number of zero-length barrier bios that will be submitted
 199          * to the target for the purpose of flushing cache.
 200          *
 201          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 202          * It is a responsibility of the target driver to remap these bios
 203          * to the real underlying devices.
 204          */
 205         unsigned num_flush_bios;
 206
 207         /*
 208          * The number of discard bios that will be submitted to the target.
 209          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 210          */
 211         unsigned num_discard_bios;
 212
 213         /*
 214          * The number of WRITE SAME bios that will be submitted to the target.
 215          * The bio number can be accessed with dm_bio_get_target_bio_nr.
 216          */
 217         unsigned num_write_same_bios;
 218
 219         /*
 220          * The minimum number of extra bytes allocated in each bio for the
 221          * target to use.  dm_per_bio_data returns the data location.
 222          */
 223         unsigned per_bio_data_size;
 224
 225         /*
 226          * If defined, this function is called to find out how many
 227          * duplicate bios should be sent to the target when writing
 228          * data.
 229          */
 230         dm_num_write_bios_fn num_write_bios;
 231
 232         /* target specific data */
 233         void *private;
 234
 235         /* Used to provide an error string from the ctr */
 236         char *error;
 237
 238         /*
 239          * Set if this target needs to receive flushes regardless of
 240          * whether or not its underlying devices have support.
 241          */
 242         bool flush_supported:1;
 243
 244         /*
 245          * Set if this target needs to receive discards regardless of
 246          * whether or not its underlying devices have support.
 247          */
 248         bool discards_supported:1;
 249
 250         /*
 251          * Set if the target required discard bios to be split
 252          * on max_io_len boundary.
 253          */
 254         bool split_discard_bios:1;
 255
 256         /*
 257          * Set if this target does not return zeroes on discarded blocks.
 258          */
 259         bool discard_zeroes_data_unsupported:1;
 260 };
 261
 262 /* Each target can link one of these into the table */
 263 struct dm_target_callbacks {
 264         struct list_head list;
 265         int (*congested_fn) (struct dm_target_callbacks *, int);
 266 };
 267
 268 /*
 269  * For bio-based dm.
 270  * One of these is allocated for each bio.
 271  * This structure shouldn't be touched directly by target drivers.
 272  * It is here so that we can inline dm_per_bio_data and
 273  * dm_bio_from_per_bio_data
 274  */
 275 struct dm_target_io {
 276         struct dm_io *io;
 277         struct dm_target *ti;
 278         union map_info info;
 279         unsigned target_bio_nr;
 280         struct bio clone;
 281 };
 282
 283 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
 284 {
 285         return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
 286 }
 287
 288 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
 289 {
 290         return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
 291 }
 292
 293 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
 294 {
 295         return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
 296 }
 297
 298 int dm_register_target(struct target_type *t);
 299 void dm_unregister_target(struct target_type *t);
 300
 301 /*
 302  * Target argument parsing.
 303  */
 304 struct dm_arg_set {
 305         unsigned argc;
 306         char **argv;
 307 };
 308
 309 /*
 310  * The minimum and maximum value of a numeric argument, together with
 311  * the error message to use if the number is found to be outside that range.
 312  */
 313 struct dm_arg {
 314         unsigned min;
 315         unsigned max;
 316         char *error;
 317 };
 318
 319 /*
 320  * Validate the next argument, either returning it as *value or, if invalid,
 321  * returning -EINVAL and setting *error.
 322  */
 323 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 324                 unsigned *value, char **error);
 325
 326 /*
 327  * Process the next argument as the start of a group containing between
 328  * arg->min and arg->max further arguments. Either return the size as
 329  * *num_args or, if invalid, return -EINVAL and set *error.
 330  */
 331 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 332                       unsigned *num_args, char **error);
 333
 334 /*
 335  * Return the current argument and shift to the next.
 336  */
 337 const char *dm_shift_arg(struct dm_arg_set *as);
 338
 339 /*
 340  * Move through num_args arguments.
 341  */
 342 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 343
 344 /*-----------------------------------------------------------------
 345  * Functions for creating and manipulating mapped devices.
 346  * Drop the reference with dm_put when you finish with the object.
 347  *---------------------------------------------------------------*/
 348
 349 /*
 350  * DM_ANY_MINOR chooses the next available minor number.
 351  */
 352 #define DM_ANY_MINOR (-1)
 353 int dm_create(int minor, struct mapped_device **md);
 354
 355 /*
 356  * Reference counting for md.
 357  */
 358 struct mapped_device *dm_get_md(dev_t dev);
 359 void dm_get(struct mapped_device *md);
 360 void dm_put(struct mapped_device *md);
 361
 362 /*
 363  * An arbitrary pointer may be stored alongside a mapped device.
 364  */
 365 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 366 void *dm_get_mdptr(struct mapped_device *md);
 367
 368 /*
 369  * A device can still be used while suspended, but I/O is deferred.
 370  */
 371 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 372 int dm_resume(struct mapped_device *md);
 373
 374 /*
 375  * Event functions.
 376  */
 377 uint32_t dm_get_event_nr(struct mapped_device *md);
 378 int dm_wait_event(struct mapped_device *md, int event_nr);
 379 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 380 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 381
 382 /*
 383  * Info functions.
 384  */
 385 const char *dm_device_name(struct mapped_device *md);
 386 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 387 struct gendisk *dm_disk(struct mapped_device *md);
 388 int dm_suspended(struct dm_target *ti);
 389 int dm_noflush_suspending(struct dm_target *ti);
 390 union map_info *dm_get_mapinfo(struct bio *bio);
 391 union map_info *dm_get_rq_mapinfo(struct request *rq);
 392
 393 /*
 394  * Geometry functions.
 395  */
 396 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 397 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 398
 399
 400 /*-----------------------------------------------------------------
 401  * Functions for manipulating device-mapper tables.
 402  *---------------------------------------------------------------*/
 403
 404 /*
 405  * First create an empty table.
 406  */
 407 int dm_table_create(struct dm_table **result, fmode_t mode,
 408                     unsigned num_targets, struct mapped_device *md);
 409
 410 /*
 411  * Then call this once for each target.
 412  */
 413 int dm_table_add_target(struct dm_table *t, const char *type,
 414                         sector_t start, sector_t len, char *params);
 415
 416 /*
 417  * Target_ctr should call this if it needs to add any callbacks.
 418  */
 419 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 420
 421 /*
 422  * Finally call this to make the table ready for use.
 423  */
 424 int dm_table_complete(struct dm_table *t);
 425
 426 /*
 427  * Target may require that it is never sent I/O larger than len.
 428  */
 429 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 430
 431 /*
 432  * Table reference counting.
 433  */
 434 struct dm_table *dm_get_live_table(struct mapped_device *md);
 435 void dm_table_get(struct dm_table *t);
 436 void dm_table_put(struct dm_table *t);
 437
 438 /*
 439  * Queries
 440  */
 441 sector_t dm_table_get_size(struct dm_table *t);
 442 unsigned int dm_table_get_num_targets(struct dm_table *t);
 443 fmode_t dm_table_get_mode(struct dm_table *t);
 444 struct mapped_device *dm_table_get_md(struct dm_table *t);
 445
 446 /*
 447  * Trigger an event.
 448  */
 449 void dm_table_event(struct dm_table *t);
 450
 451 /*
 452  * The device must be suspended before calling this method.
 453  * Returns the previous table, which the caller must destroy.
 454  */
 455 struct dm_table *dm_swap_table(struct mapped_device *md,
 456                                struct dm_table *t);
 457
 458 /*
 459  * A wrapper around vmalloc.
 460  */
 461 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 462
 463 /*-----------------------------------------------------------------
 464  * Macros.
 465  *---------------------------------------------------------------*/
 466 #define DM_NAME "device-mapper"
 467
 468 #ifdef CONFIG_PRINTK
 469 extern struct ratelimit_state dm_ratelimit_state;
 470
 471 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 472 #else
 473 #define dm_ratelimit()  0
 474 #endif
 475
 476 #define DMCRIT(f, arg...) \
 477         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 478
 479 #define DMERR(f, arg...) \
 480         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 481 #define DMERR_LIMIT(f, arg...) \
 482         do { \
 483                 if (dm_ratelimit())     \
 484                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 485                                f "\n", ## arg); \
 486         } while (0)
 487
 488 #define DMWARN(f, arg...) \
 489         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 490 #define DMWARN_LIMIT(f, arg...) \
 491         do { \
 492                 if (dm_ratelimit())     \
 493                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 494                                f "\n", ## arg); \
 495         } while (0)
 496
 497 #define DMINFO(f, arg...) \
 498         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 499 #define DMINFO_LIMIT(f, arg...) \
 500         do { \
 501                 if (dm_ratelimit())     \
 502                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 503                                "\n", ## arg); \
 504         } while (0)
 505
 506 #ifdef CONFIG_DM_DEBUG
 507 #  define DMDEBUG(f, arg...) \
 508         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 509 #  define DMDEBUG_LIMIT(f, arg...) \
 510         do { \
 511                 if (dm_ratelimit())     \
 512                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 513                                "\n", ## arg); \
 514         } while (0)
 515 #else
 516 #  define DMDEBUG(f, arg...) do {} while (0)
 517 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 518 #endif
 519
 520 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 521                           0 : scnprintf(result + sz, maxlen - sz, x))
 522
 523 #define SECTOR_SHIFT 9
 524
 525 /*
 526  * Definitions of return values from target end_io function.
 527  */
 528 #define DM_ENDIO_INCOMPLETE     1
 529 #define DM_ENDIO_REQUEUE        2
 530
 531 /*
 532  * Definitions of return values from target map function.
 533  */
 534 #define DM_MAPIO_SUBMITTED      0
 535 #define DM_MAPIO_REMAPPED       1
 536 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 537
 538 /*
 539  * Ceiling(n / sz)
 540  */
 541 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 542
 543 #define dm_sector_div_up(n, sz) ( \
 544 { \
 545         sector_t _r = ((n) + (sz) - 1); \
 546         sector_div(_r, (sz)); \
 547         _r; \
 548 } \
 549 )
 550
 551 /*
 552  * ceiling(n / size) * size
 553  */
 554 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 555
 556 #define dm_array_too_big(fixed, obj, num) \
 557         ((num) > (UINT_MAX - (fixed)) / (obj))
 558
 559 /*
 560  * Sector offset taken relative to the start of the target instead of
 561  * relative to the start of the device.
 562  */
 563 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 564
 565 static inline sector_t to_sector(unsigned long n)
 566 {
 567         return (n >> SECTOR_SHIFT);
 568 }
 569
 570 static inline unsigned long to_bytes(sector_t n)
 571 {
 572         return (n << SECTOR_SHIFT);
 573 }
 574
 575 /*-----------------------------------------------------------------
 576  * Helper for block layer and dm core operations
 577  *---------------------------------------------------------------*/
 578 void dm_dispatch_request(struct request *rq);
 579 void dm_requeue_unmapped_request(struct request *rq);
 580 void dm_kill_unmapped_request(struct request *rq, int error);
 581 int dm_underlying_device_busy(struct request_queue *q);
 582
 583 #endif  /* _LINUX_DEVICE_MAPPER_H */