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         unsigned target_request_nr;
  27 };
  28
  29 /*
  30  * In the constructor the target parameter will already have the
  31  * table, type, begin and len fields filled in.
  32  */
  33 typedef int (*dm_ctr_fn) (struct dm_target *target,
  34                           unsigned int argc, char **argv);
  35
  36 /*
  37  * The destructor doesn't need to free the dm_target, just
  38  * anything hidden ti->private.
  39  */
  40 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  41
  42 /*
  43  * The map function must return:
  44  * < 0: error
  45  * = 0: The target will handle the io by resubmitting it later
  46  * = 1: simple remap complete
  47  * = 2: The target wants to push back the io
  48  */
  49 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
  50                           union map_info *map_context);
  51 typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone,
  52                                   union map_info *map_context);
  53
  54 /*
  55  * Returns:
  56  * < 0 : error (currently ignored)
  57  * 0   : ended successfully
  58  * 1   : for some reason the io has still not completed (eg,
  59  *       multipath target might want to requeue a failed io).
  60  * 2   : The target wants to push back the io
  61  */
  62 typedef int (*dm_endio_fn) (struct dm_target *ti,
  63                             struct bio *bio, int error,
  64                             union map_info *map_context);
  65 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  66                                     struct request *clone, int error,
  67                                     union map_info *map_context);
  68
  69 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  70 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  71 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  72 typedef void (*dm_resume_fn) (struct dm_target *ti);
  73
  74 typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  75                              char *result, unsigned int maxlen);
  76
  77 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  78
  79 typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
  80                             unsigned long arg);
  81
  82 typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
  83                             struct bio_vec *biovec, int max_size);
  84
  85 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
  86                                            struct dm_dev *dev,
  87                                            sector_t start, sector_t len,
  88                                            void *data);
  89
  90 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
  91                                       iterate_devices_callout_fn fn,
  92                                       void *data);
  93
  94 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
  95                                 struct queue_limits *limits);
  96
  97 /*
  98  * Returns:
  99  *    0: The target can handle the next I/O immediately.
 100  *    1: The target can't handle the next I/O immediately.
 101  */
 102 typedef int (*dm_busy_fn) (struct dm_target *ti);
 103
 104 void dm_error(const char *message);
 105
 106 /*
 107  * Combine device limits.
 108  */
 109 int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 110                          sector_t start, sector_t len, void *data);
 111
 112 struct dm_dev {
 113         struct block_device *bdev;
 114         fmode_t mode;
 115         char name[16];
 116 };
 117
 118 /*
 119  * Constructors should call these functions to ensure destination devices
 120  * are opened/closed correctly.
 121  */
 122 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 123                                                  struct dm_dev **result);
 124 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 125
 126 /*
 127  * Information about a target type
 128  */
 129
 130 struct target_type {
 131         uint64_t features;
 132         const char *name;
 133         struct module *module;
 134         unsigned version[3];
 135         dm_ctr_fn ctr;
 136         dm_dtr_fn dtr;
 137         dm_map_fn map;
 138         dm_map_request_fn map_rq;
 139         dm_endio_fn end_io;
 140         dm_request_endio_fn rq_end_io;
 141         dm_presuspend_fn presuspend;
 142         dm_postsuspend_fn postsuspend;
 143         dm_preresume_fn preresume;
 144         dm_resume_fn resume;
 145         dm_status_fn status;
 146         dm_message_fn message;
 147         dm_ioctl_fn ioctl;
 148         dm_merge_fn merge;
 149         dm_busy_fn busy;
 150         dm_iterate_devices_fn iterate_devices;
 151         dm_io_hints_fn io_hints;
 152
 153         /* For internal device-mapper use. */
 154         struct list_head list;
 155 };
 156
 157 /*
 158  * Target features
 159  */
 160
 161 /*
 162  * Any table that contains an instance of this target must have only one.
 163  */
 164 #define DM_TARGET_SINGLETON             0x00000001
 165 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
 166
 167 /*
 168  * Indicates that a target does not support read-only devices.
 169  */
 170 #define DM_TARGET_ALWAYS_WRITEABLE      0x00000002
 171 #define dm_target_always_writeable(type) \
 172                 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
 173
 174 /*
 175  * Any device that contains a table with an instance of this target may never
 176  * have tables containing any different target type.
 177  */
 178 #define DM_TARGET_IMMUTABLE             0x00000004
 179 #define dm_target_is_immutable(type)    ((type)->features & DM_TARGET_IMMUTABLE)
 180
 181 struct dm_target {
 182         struct dm_table *table;
 183         struct target_type *type;
 184
 185         /* target limits */
 186         sector_t begin;
 187         sector_t len;
 188
 189         /* If non-zero, maximum size of I/O submitted to a target. */
 190         uint32_t max_io_len;
 191
 192         /*
 193          * A number of zero-length barrier requests that will be submitted
 194          * to the target for the purpose of flushing cache.
 195          *
 196          * The request number will be placed in union map_info->target_request_nr.
 197          * It is a responsibility of the target driver to remap these requests
 198          * to the real underlying devices.
 199          */
 200         unsigned num_flush_requests;
 201
 202         /*
 203          * The number of discard requests that will be submitted to the
 204          * target.  map_info->request_nr is used just like num_flush_requests.
 205          */
 206         unsigned num_discard_requests;
 207
 208         /* target specific data */
 209         void *private;
 210
 211         /* Used to provide an error string from the ctr */
 212         char *error;
 213
 214         /*
 215          * Set if this target needs to receive flushes regardless of
 216          * whether or not its underlying devices have support.
 217          */
 218         bool flush_supported:1;
 219
 220         /*
 221          * Set if this target needs to receive discards regardless of
 222          * whether or not its underlying devices have support.
 223          */
 224         unsigned discards_supported:1;
 225
 226         /*
 227          * Set if the target required discard request to be split
 228          * on max_io_len boundary.
 229          */
 230         unsigned split_discard_requests:1;
 231
 232         /*
 233          * Set if this target does not return zeroes on discarded blocks.
 234          */
 235         unsigned discard_zeroes_data_unsupported:1;
 236 };
 237
 238 /* Each target can link one of these into the table */
 239 struct dm_target_callbacks {
 240         struct list_head list;
 241         int (*congested_fn) (struct dm_target_callbacks *, int);
 242 };
 243
 244 int dm_register_target(struct target_type *t);
 245 void dm_unregister_target(struct target_type *t);
 246
 247 /*
 248  * Target argument parsing.
 249  */
 250 struct dm_arg_set {
 251         unsigned argc;
 252         char **argv;
 253 };
 254
 255 /*
 256  * The minimum and maximum value of a numeric argument, together with
 257  * the error message to use if the number is found to be outside that range.
 258  */
 259 struct dm_arg {
 260         unsigned min;
 261         unsigned max;
 262         char *error;
 263 };
 264
 265 /*
 266  * Validate the next argument, either returning it as *value or, if invalid,
 267  * returning -EINVAL and setting *error.
 268  */
 269 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 270                 unsigned *value, char **error);
 271
 272 /*
 273  * Process the next argument as the start of a group containing between
 274  * arg->min and arg->max further arguments. Either return the size as
 275  * *num_args or, if invalid, return -EINVAL and set *error.
 276  */
 277 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 278                       unsigned *num_args, char **error);
 279
 280 /*
 281  * Return the current argument and shift to the next.
 282  */
 283 const char *dm_shift_arg(struct dm_arg_set *as);
 284
 285 /*
 286  * Move through num_args arguments.
 287  */
 288 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 289
 290 /*-----------------------------------------------------------------
 291  * Functions for creating and manipulating mapped devices.
 292  * Drop the reference with dm_put when you finish with the object.
 293  *---------------------------------------------------------------*/
 294
 295 /*
 296  * DM_ANY_MINOR chooses the next available minor number.
 297  */
 298 #define DM_ANY_MINOR (-1)
 299 int dm_create(int minor, struct mapped_device **md);
 300
 301 /*
 302  * Reference counting for md.
 303  */
 304 struct mapped_device *dm_get_md(dev_t dev);
 305 void dm_get(struct mapped_device *md);
 306 void dm_put(struct mapped_device *md);
 307
 308 /*
 309  * An arbitrary pointer may be stored alongside a mapped device.
 310  */
 311 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 312 void *dm_get_mdptr(struct mapped_device *md);
 313
 314 /*
 315  * A device can still be used while suspended, but I/O is deferred.
 316  */
 317 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 318 int dm_resume(struct mapped_device *md);
 319
 320 /*
 321  * Event functions.
 322  */
 323 uint32_t dm_get_event_nr(struct mapped_device *md);
 324 int dm_wait_event(struct mapped_device *md, int event_nr);
 325 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 326 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 327
 328 /*
 329  * Info functions.
 330  */
 331 const char *dm_device_name(struct mapped_device *md);
 332 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 333 struct gendisk *dm_disk(struct mapped_device *md);
 334 int dm_suspended(struct dm_target *ti);
 335 int dm_noflush_suspending(struct dm_target *ti);
 336 union map_info *dm_get_mapinfo(struct bio *bio);
 337 union map_info *dm_get_rq_mapinfo(struct request *rq);
 338
 339 /*
 340  * Geometry functions.
 341  */
 342 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 343 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 344
 345
 346 /*-----------------------------------------------------------------
 347  * Functions for manipulating device-mapper tables.
 348  *---------------------------------------------------------------*/
 349
 350 /*
 351  * First create an empty table.
 352  */
 353 int dm_table_create(struct dm_table **result, fmode_t mode,
 354                     unsigned num_targets, struct mapped_device *md);
 355
 356 /*
 357  * Then call this once for each target.
 358  */
 359 int dm_table_add_target(struct dm_table *t, const char *type,
 360                         sector_t start, sector_t len, char *params);
 361
 362 /*
 363  * Target_ctr should call this if it needs to add any callbacks.
 364  */
 365 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 366
 367 /*
 368  * Finally call this to make the table ready for use.
 369  */
 370 int dm_table_complete(struct dm_table *t);
 371
 372 /*
 373  * Target may require that it is never sent I/O larger than len.
 374  */
 375 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 376
 377 /*
 378  * Table reference counting.
 379  */
 380 struct dm_table *dm_get_live_table(struct mapped_device *md);
 381 void dm_table_get(struct dm_table *t);
 382 void dm_table_put(struct dm_table *t);
 383
 384 /*
 385  * Queries
 386  */
 387 sector_t dm_table_get_size(struct dm_table *t);
 388 unsigned int dm_table_get_num_targets(struct dm_table *t);
 389 fmode_t dm_table_get_mode(struct dm_table *t);
 390 struct mapped_device *dm_table_get_md(struct dm_table *t);
 391
 392 /*
 393  * Trigger an event.
 394  */
 395 void dm_table_event(struct dm_table *t);
 396
 397 /*
 398  * The device must be suspended before calling this method.
 399  * Returns the previous table, which the caller must destroy.
 400  */
 401 struct dm_table *dm_swap_table(struct mapped_device *md,
 402                                struct dm_table *t);
 403
 404 /*
 405  * A wrapper around vmalloc.
 406  */
 407 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 408
 409 /*-----------------------------------------------------------------
 410  * Macros.
 411  *---------------------------------------------------------------*/
 412 #define DM_NAME "device-mapper"
 413
 414 #ifdef CONFIG_PRINTK
 415 extern struct ratelimit_state dm_ratelimit_state;
 416
 417 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 418 #else
 419 #define dm_ratelimit()  0
 420 #endif
 421
 422 #define DMCRIT(f, arg...) \
 423         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 424
 425 #define DMERR(f, arg...) \
 426         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 427 #define DMERR_LIMIT(f, arg...) \
 428         do { \
 429                 if (dm_ratelimit())     \
 430                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 431                                f "\n", ## arg); \
 432         } while (0)
 433
 434 #define DMWARN(f, arg...) \
 435         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 436 #define DMWARN_LIMIT(f, arg...) \
 437         do { \
 438                 if (dm_ratelimit())     \
 439                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 440                                f "\n", ## arg); \
 441         } while (0)
 442
 443 #define DMINFO(f, arg...) \
 444         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 445 #define DMINFO_LIMIT(f, arg...) \
 446         do { \
 447                 if (dm_ratelimit())     \
 448                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 449                                "\n", ## arg); \
 450         } while (0)
 451
 452 #ifdef CONFIG_DM_DEBUG
 453 #  define DMDEBUG(f, arg...) \
 454         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 455 #  define DMDEBUG_LIMIT(f, arg...) \
 456         do { \
 457                 if (dm_ratelimit())     \
 458                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 459                                "\n", ## arg); \
 460         } while (0)
 461 #else
 462 #  define DMDEBUG(f, arg...) do {} while (0)
 463 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 464 #endif
 465
 466 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 467                           0 : scnprintf(result + sz, maxlen - sz, x))
 468
 469 #define SECTOR_SHIFT 9
 470
 471 /*
 472  * Definitions of return values from target end_io function.
 473  */
 474 #define DM_ENDIO_INCOMPLETE     1
 475 #define DM_ENDIO_REQUEUE        2
 476
 477 /*
 478  * Definitions of return values from target map function.
 479  */
 480 #define DM_MAPIO_SUBMITTED      0
 481 #define DM_MAPIO_REMAPPED       1
 482 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 483
 484 /*
 485  * Ceiling(n / sz)
 486  */
 487 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 488
 489 #define dm_sector_div_up(n, sz) ( \
 490 { \
 491         sector_t _r = ((n) + (sz) - 1); \
 492         sector_div(_r, (sz)); \
 493         _r; \
 494 } \
 495 )
 496
 497 /*
 498  * ceiling(n / size) * size
 499  */
 500 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 501
 502 #define dm_array_too_big(fixed, obj, num) \
 503         ((num) > (UINT_MAX - (fixed)) / (obj))
 504
 505 /*
 506  * Sector offset taken relative to the start of the target instead of
 507  * relative to the start of the device.
 508  */
 509 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 510
 511 static inline sector_t to_sector(unsigned long n)
 512 {
 513         return (n >> SECTOR_SHIFT);
 514 }
 515
 516 static inline unsigned long to_bytes(sector_t n)
 517 {
 518         return (n << SECTOR_SHIFT);
 519 }
 520
 521 /*-----------------------------------------------------------------
 522  * Helper for block layer and dm core operations
 523  *---------------------------------------------------------------*/
 524 void dm_dispatch_request(struct request *rq);
 525 void dm_requeue_unmapped_request(struct request *rq);
 526 void dm_kill_unmapped_request(struct request *rq, int error);
 527 int dm_underlying_device_busy(struct request_queue *q);
 528
 529 #endif  /* _LINUX_DEVICE_MAPPER_H */