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 discards regardless of
 216          * whether or not its underlying devices have support.
 217          */
 218         unsigned discards_supported:1;
 219
 220         /*
 221          * Set if the target required discard request to be split
 222          * on max_io_len boundary.
 223          */
 224         unsigned split_discard_requests:1;
 225
 226         /*
 227          * Set if this target does not return zeroes on discarded blocks.
 228          */
 229         unsigned discard_zeroes_data_unsupported:1;
 230 };
 231
 232 /* Each target can link one of these into the table */
 233 struct dm_target_callbacks {
 234         struct list_head list;
 235         int (*congested_fn) (struct dm_target_callbacks *, int);
 236 };
 237
 238 int dm_register_target(struct target_type *t);
 239 void dm_unregister_target(struct target_type *t);
 240
 241 /*
 242  * Target argument parsing.
 243  */
 244 struct dm_arg_set {
 245         unsigned argc;
 246         char **argv;
 247 };
 248
 249 /*
 250  * The minimum and maximum value of a numeric argument, together with
 251  * the error message to use if the number is found to be outside that range.
 252  */
 253 struct dm_arg {
 254         unsigned min;
 255         unsigned max;
 256         char *error;
 257 };
 258
 259 /*
 260  * Validate the next argument, either returning it as *value or, if invalid,
 261  * returning -EINVAL and setting *error.
 262  */
 263 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 264                 unsigned *value, char **error);
 265
 266 /*
 267  * Process the next argument as the start of a group containing between
 268  * arg->min and arg->max further arguments. Either return the size as
 269  * *num_args or, if invalid, return -EINVAL and set *error.
 270  */
 271 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 272                       unsigned *num_args, char **error);
 273
 274 /*
 275  * Return the current argument and shift to the next.
 276  */
 277 const char *dm_shift_arg(struct dm_arg_set *as);
 278
 279 /*
 280  * Move through num_args arguments.
 281  */
 282 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 283
 284 /*-----------------------------------------------------------------
 285  * Functions for creating and manipulating mapped devices.
 286  * Drop the reference with dm_put when you finish with the object.
 287  *---------------------------------------------------------------*/
 288
 289 /*
 290  * DM_ANY_MINOR chooses the next available minor number.
 291  */
 292 #define DM_ANY_MINOR (-1)
 293 int dm_create(int minor, struct mapped_device **md);
 294
 295 /*
 296  * Reference counting for md.
 297  */
 298 struct mapped_device *dm_get_md(dev_t dev);
 299 void dm_get(struct mapped_device *md);
 300 void dm_put(struct mapped_device *md);
 301
 302 /*
 303  * An arbitrary pointer may be stored alongside a mapped device.
 304  */
 305 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 306 void *dm_get_mdptr(struct mapped_device *md);
 307
 308 /*
 309  * A device can still be used while suspended, but I/O is deferred.
 310  */
 311 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 312 int dm_resume(struct mapped_device *md);
 313
 314 /*
 315  * Event functions.
 316  */
 317 uint32_t dm_get_event_nr(struct mapped_device *md);
 318 int dm_wait_event(struct mapped_device *md, int event_nr);
 319 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 320 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 321
 322 /*
 323  * Info functions.
 324  */
 325 const char *dm_device_name(struct mapped_device *md);
 326 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 327 struct gendisk *dm_disk(struct mapped_device *md);
 328 int dm_suspended(struct dm_target *ti);
 329 int dm_noflush_suspending(struct dm_target *ti);
 330 union map_info *dm_get_mapinfo(struct bio *bio);
 331 union map_info *dm_get_rq_mapinfo(struct request *rq);
 332
 333 /*
 334  * Geometry functions.
 335  */
 336 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 337 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 338
 339
 340 /*-----------------------------------------------------------------
 341  * Functions for manipulating device-mapper tables.
 342  *---------------------------------------------------------------*/
 343
 344 /*
 345  * First create an empty table.
 346  */
 347 int dm_table_create(struct dm_table **result, fmode_t mode,
 348                     unsigned num_targets, struct mapped_device *md);
 349
 350 /*
 351  * Then call this once for each target.
 352  */
 353 int dm_table_add_target(struct dm_table *t, const char *type,
 354                         sector_t start, sector_t len, char *params);
 355
 356 /*
 357  * Target_ctr should call this if it needs to add any callbacks.
 358  */
 359 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 360
 361 /*
 362  * Finally call this to make the table ready for use.
 363  */
 364 int dm_table_complete(struct dm_table *t);
 365
 366 /*
 367  * Target may require that it is never sent I/O larger than len.
 368  */
 369 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 370
 371 /*
 372  * Table reference counting.
 373  */
 374 struct dm_table *dm_get_live_table(struct mapped_device *md);
 375 void dm_table_get(struct dm_table *t);
 376 void dm_table_put(struct dm_table *t);
 377
 378 /*
 379  * Queries
 380  */
 381 sector_t dm_table_get_size(struct dm_table *t);
 382 unsigned int dm_table_get_num_targets(struct dm_table *t);
 383 fmode_t dm_table_get_mode(struct dm_table *t);
 384 struct mapped_device *dm_table_get_md(struct dm_table *t);
 385
 386 /*
 387  * Trigger an event.
 388  */
 389 void dm_table_event(struct dm_table *t);
 390
 391 /*
 392  * The device must be suspended before calling this method.
 393  * Returns the previous table, which the caller must destroy.
 394  */
 395 struct dm_table *dm_swap_table(struct mapped_device *md,
 396                                struct dm_table *t);
 397
 398 /*
 399  * A wrapper around vmalloc.
 400  */
 401 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 402
 403 /*-----------------------------------------------------------------
 404  * Macros.
 405  *---------------------------------------------------------------*/
 406 #define DM_NAME "device-mapper"
 407
 408 #ifdef CONFIG_PRINTK
 409 extern struct ratelimit_state dm_ratelimit_state;
 410
 411 #define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 412 #else
 413 #define dm_ratelimit()  0
 414 #endif
 415
 416 #define DMCRIT(f, arg...) \
 417         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 418
 419 #define DMERR(f, arg...) \
 420         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 421 #define DMERR_LIMIT(f, arg...) \
 422         do { \
 423                 if (dm_ratelimit())     \
 424                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 425                                f "\n", ## arg); \
 426         } while (0)
 427
 428 #define DMWARN(f, arg...) \
 429         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 430 #define DMWARN_LIMIT(f, arg...) \
 431         do { \
 432                 if (dm_ratelimit())     \
 433                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 434                                f "\n", ## arg); \
 435         } while (0)
 436
 437 #define DMINFO(f, arg...) \
 438         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 439 #define DMINFO_LIMIT(f, arg...) \
 440         do { \
 441                 if (dm_ratelimit())     \
 442                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 443                                "\n", ## arg); \
 444         } while (0)
 445
 446 #ifdef CONFIG_DM_DEBUG
 447 #  define DMDEBUG(f, arg...) \
 448         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 449 #  define DMDEBUG_LIMIT(f, arg...) \
 450         do { \
 451                 if (dm_ratelimit())     \
 452                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 453                                "\n", ## arg); \
 454         } while (0)
 455 #else
 456 #  define DMDEBUG(f, arg...) do {} while (0)
 457 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 458 #endif
 459
 460 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 461                           0 : scnprintf(result + sz, maxlen - sz, x))
 462
 463 #define SECTOR_SHIFT 9
 464
 465 /*
 466  * Definitions of return values from target end_io function.
 467  */
 468 #define DM_ENDIO_INCOMPLETE     1
 469 #define DM_ENDIO_REQUEUE        2
 470
 471 /*
 472  * Definitions of return values from target map function.
 473  */
 474 #define DM_MAPIO_SUBMITTED      0
 475 #define DM_MAPIO_REMAPPED       1
 476 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 477
 478 /*
 479  * Ceiling(n / sz)
 480  */
 481 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 482
 483 #define dm_sector_div_up(n, sz) ( \
 484 { \
 485         sector_t _r = ((n) + (sz) - 1); \
 486         sector_div(_r, (sz)); \
 487         _r; \
 488 } \
 489 )
 490
 491 /*
 492  * ceiling(n / size) * size
 493  */
 494 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 495
 496 #define dm_array_too_big(fixed, obj, num) \
 497         ((num) > (UINT_MAX - (fixed)) / (obj))
 498
 499 /*
 500  * Sector offset taken relative to the start of the target instead of
 501  * relative to the start of the device.
 502  */
 503 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 504
 505 static inline sector_t to_sector(unsigned long n)
 506 {
 507         return (n >> SECTOR_SHIFT);
 508 }
 509
 510 static inline unsigned long to_bytes(sector_t n)
 511 {
 512         return (n << SECTOR_SHIFT);
 513 }
 514
 515 /*-----------------------------------------------------------------
 516  * Helper for block layer and dm core operations
 517  *---------------------------------------------------------------*/
 518 void dm_dispatch_request(struct request *rq);
 519 void dm_requeue_unmapped_request(struct request *rq);
 520 void dm_kill_unmapped_request(struct request *rq, int error);
 521 int dm_underlying_device_busy(struct request_queue *q);
 522
 523 #endif  /* _LINUX_DEVICE_MAPPER_H */