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