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 #define DM_TARGET_ALWAYS_WRITEABLE      0x00000002
 170 #define dm_target_always_writeable(type) \
 171                 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
 172
 173 struct dm_target {
 174         struct dm_table *table;
 175         struct target_type *type;
 176
 177         /* target limits */
 178         sector_t begin;
 179         sector_t len;
 180
 181         /* Always a power of 2 */
 182         sector_t split_io;
 183
 184         /*
 185          * A number of zero-length barrier requests that will be submitted
 186          * to the target for the purpose of flushing cache.
 187          *
 188          * The request number will be placed in union map_info->target_request_nr.
 189          * It is a responsibility of the target driver to remap these requests
 190          * to the real underlying devices.
 191          */
 192         unsigned num_flush_requests;
 193
 194         /*
 195          * The number of discard requests that will be submitted to the
 196          * target.  map_info->request_nr is used just like num_flush_requests.
 197          */
 198         unsigned num_discard_requests;
 199
 200         /* target specific data */
 201         void *private;
 202
 203         /* Used to provide an error string from the ctr */
 204         char *error;
 205
 206         /*
 207          * Set if this target needs to receive discards regardless of
 208          * whether or not its underlying devices have support.
 209          */
 210         unsigned discards_supported:1;
 211
 212         /*
 213          * Set if this target does not return zeroes on discarded blocks.
 214          */
 215         unsigned discard_zeroes_data_unsupported:1;
 216 };
 217
 218 /* Each target can link one of these into the table */
 219 struct dm_target_callbacks {
 220         struct list_head list;
 221         int (*congested_fn) (struct dm_target_callbacks *, int);
 222 };
 223
 224 int dm_register_target(struct target_type *t);
 225 void dm_unregister_target(struct target_type *t);
 226
 227 /*
 228  * Target argument parsing.
 229  */
 230 struct dm_arg_set {
 231         unsigned argc;
 232         char **argv;
 233 };
 234
 235 /*
 236  * The minimum and maximum value of a numeric argument, together with
 237  * the error message to use if the number is found to be outside that range.
 238  */
 239 struct dm_arg {
 240         unsigned min;
 241         unsigned max;
 242         char *error;
 243 };
 244
 245 /*
 246  * Validate the next argument, either returning it as *value or, if invalid,
 247  * returning -EINVAL and setting *error.
 248  */
 249 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 250                 unsigned *value, char **error);
 251
 252 /*
 253  * Process the next argument as the start of a group containing between
 254  * arg->min and arg->max further arguments. Either return the size as
 255  * *num_args or, if invalid, return -EINVAL and set *error.
 256  */
 257 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 258                       unsigned *num_args, char **error);
 259
 260 /*
 261  * Return the current argument and shift to the next.
 262  */
 263 const char *dm_shift_arg(struct dm_arg_set *as);
 264
 265 /*
 266  * Move through num_args arguments.
 267  */
 268 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 269
 270 /*-----------------------------------------------------------------
 271  * Functions for creating and manipulating mapped devices.
 272  * Drop the reference with dm_put when you finish with the object.
 273  *---------------------------------------------------------------*/
 274
 275 /*
 276  * DM_ANY_MINOR chooses the next available minor number.
 277  */
 278 #define DM_ANY_MINOR (-1)
 279 int dm_create(int minor, struct mapped_device **md);
 280
 281 /*
 282  * Reference counting for md.
 283  */
 284 struct mapped_device *dm_get_md(dev_t dev);
 285 void dm_get(struct mapped_device *md);
 286 void dm_put(struct mapped_device *md);
 287
 288 /*
 289  * An arbitrary pointer may be stored alongside a mapped device.
 290  */
 291 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 292 void *dm_get_mdptr(struct mapped_device *md);
 293
 294 /*
 295  * A device can still be used while suspended, but I/O is deferred.
 296  */
 297 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 298 int dm_resume(struct mapped_device *md);
 299
 300 /*
 301  * Event functions.
 302  */
 303 uint32_t dm_get_event_nr(struct mapped_device *md);
 304 int dm_wait_event(struct mapped_device *md, int event_nr);
 305 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 306 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 307
 308 /*
 309  * Info functions.
 310  */
 311 const char *dm_device_name(struct mapped_device *md);
 312 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 313 struct gendisk *dm_disk(struct mapped_device *md);
 314 int dm_suspended(struct dm_target *ti);
 315 int dm_noflush_suspending(struct dm_target *ti);
 316 union map_info *dm_get_mapinfo(struct bio *bio);
 317 union map_info *dm_get_rq_mapinfo(struct request *rq);
 318
 319 /*
 320  * Geometry functions.
 321  */
 322 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 323 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 324
 325
 326 /*-----------------------------------------------------------------
 327  * Functions for manipulating device-mapper tables.
 328  *---------------------------------------------------------------*/
 329
 330 /*
 331  * First create an empty table.
 332  */
 333 int dm_table_create(struct dm_table **result, fmode_t mode,
 334                     unsigned num_targets, struct mapped_device *md);
 335
 336 /*
 337  * Then call this once for each target.
 338  */
 339 int dm_table_add_target(struct dm_table *t, const char *type,
 340                         sector_t start, sector_t len, char *params);
 341
 342 /*
 343  * Target_ctr should call this if it needs to add any callbacks.
 344  */
 345 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 346
 347 /*
 348  * Finally call this to make the table ready for use.
 349  */
 350 int dm_table_complete(struct dm_table *t);
 351
 352 /*
 353  * Table reference counting.
 354  */
 355 struct dm_table *dm_get_live_table(struct mapped_device *md);
 356 void dm_table_get(struct dm_table *t);
 357 void dm_table_put(struct dm_table *t);
 358
 359 /*
 360  * Queries
 361  */
 362 sector_t dm_table_get_size(struct dm_table *t);
 363 unsigned int dm_table_get_num_targets(struct dm_table *t);
 364 fmode_t dm_table_get_mode(struct dm_table *t);
 365 struct mapped_device *dm_table_get_md(struct dm_table *t);
 366
 367 /*
 368  * Trigger an event.
 369  */
 370 void dm_table_event(struct dm_table *t);
 371
 372 /*
 373  * The device must be suspended before calling this method.
 374  * Returns the previous table, which the caller must destroy.
 375  */
 376 struct dm_table *dm_swap_table(struct mapped_device *md,
 377                                struct dm_table *t);
 378
 379 /*
 380  * A wrapper around vmalloc.
 381  */
 382 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 383
 384 /*-----------------------------------------------------------------
 385  * Macros.
 386  *---------------------------------------------------------------*/
 387 #define DM_NAME "device-mapper"
 388
 389 #ifdef CONFIG_PRINTK
 390 extern struct ratelimit_state dm_ratelimit_state;
 391
 392 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 393 #else
 394 #define dm_ratelimit()  0
 395 #endif
 396
 397 #define DMCRIT(f, arg...) \
 398         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 399
 400 #define DMERR(f, arg...) \
 401         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 402 #define DMERR_LIMIT(f, arg...) \
 403         do { \
 404                 if (dm_ratelimit())     \
 405                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 406                                f "\n", ## arg); \
 407         } while (0)
 408
 409 #define DMWARN(f, arg...) \
 410         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 411 #define DMWARN_LIMIT(f, arg...) \
 412         do { \
 413                 if (dm_ratelimit())     \
 414                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 415                                f "\n", ## arg); \
 416         } while (0)
 417
 418 #define DMINFO(f, arg...) \
 419         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 420 #define DMINFO_LIMIT(f, arg...) \
 421         do { \
 422                 if (dm_ratelimit())     \
 423                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 424                                "\n", ## arg); \
 425         } while (0)
 426
 427 #ifdef CONFIG_DM_DEBUG
 428 #  define DMDEBUG(f, arg...) \
 429         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 430 #  define DMDEBUG_LIMIT(f, arg...) \
 431         do { \
 432                 if (dm_ratelimit())     \
 433                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 434                                "\n", ## arg); \
 435         } while (0)
 436 #else
 437 #  define DMDEBUG(f, arg...) do {} while (0)
 438 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 439 #endif
 440
 441 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 442                           0 : scnprintf(result + sz, maxlen - sz, x))
 443
 444 #define SECTOR_SHIFT 9
 445
 446 /*
 447  * Definitions of return values from target end_io function.
 448  */
 449 #define DM_ENDIO_INCOMPLETE     1
 450 #define DM_ENDIO_REQUEUE        2
 451
 452 /*
 453  * Definitions of return values from target map function.
 454  */
 455 #define DM_MAPIO_SUBMITTED      0
 456 #define DM_MAPIO_REMAPPED       1
 457 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 458
 459 /*
 460  * Ceiling(n / sz)
 461  */
 462 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 463
 464 #define dm_sector_div_up(n, sz) ( \
 465 { \
 466         sector_t _r = ((n) + (sz) - 1); \
 467         sector_div(_r, (sz)); \
 468         _r; \
 469 } \
 470 )
 471
 472 /*
 473  * ceiling(n / size) * size
 474  */
 475 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 476
 477 #define dm_array_too_big(fixed, obj, num) \
 478         ((num) > (UINT_MAX - (fixed)) / (obj))
 479
 480 /*
 481  * Sector offset taken relative to the start of the target instead of
 482  * relative to the start of the device.
 483  */
 484 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 485
 486 static inline sector_t to_sector(unsigned long n)
 487 {
 488         return (n >> SECTOR_SHIFT);
 489 }
 490
 491 static inline unsigned long to_bytes(sector_t n)
 492 {
 493         return (n << SECTOR_SHIFT);
 494 }
 495
 496 /*-----------------------------------------------------------------
 497  * Helper for block layer and dm core operations
 498  *---------------------------------------------------------------*/
 499 void dm_dispatch_request(struct request *rq);
 500 void dm_requeue_unmapped_request(struct request *rq);
 501 void dm_kill_unmapped_request(struct request *rq, int error);
 502 int dm_underlying_device_busy(struct request_queue *q);
 503
 504 #endif  /* _LINUX_DEVICE_MAPPER_H */