linux/include/linux/device-mapper.h
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   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
  15struct dm_dev;
  16struct dm_target;
  17struct dm_table;
  18struct mapped_device;
  19struct bio_vec;
  20
  21typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  22
  23union 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 */
  33typedef 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 */
  40typedef 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 */
  49typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
  50                          union map_info *map_context);
  51typedef 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 */
  62typedef int (*dm_endio_fn) (struct dm_target *ti,
  63                            struct bio *bio, int error,
  64                            union map_info *map_context);
  65typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  66                                    struct request *clone, int error,
  67                                    union map_info *map_context);
  68
  69typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  70typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  71typedef int (*dm_preresume_fn) (struct dm_target *ti);
  72typedef void (*dm_resume_fn) (struct dm_target *ti);
  73
  74typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  75                             unsigned status_flags, char *result, unsigned maxlen);
  76
  77typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  78
  79typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
  80                            unsigned long arg);
  81
  82typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
  83                            struct bio_vec *biovec, int max_size);
  84
  85typedef 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
  90typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
  91                                      iterate_devices_callout_fn fn,
  92                                      void *data);
  93
  94typedef 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 */
 102typedef int (*dm_busy_fn) (struct dm_target *ti);
 103
 104void dm_error(const char *message);
 105
 106/*
 107 * Combine device limits.
 108 */
 109int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 110                         sector_t start, sector_t len, void *data);
 111
 112struct 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 */
 122int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 123                                                 struct dm_dev **result);
 124void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 125
 126/*
 127 * Information about a target type
 128 */
 129
 130struct 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
 181struct 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        bool discards_supported:1;
 225
 226        /*
 227         * Set if the target required discard request to be split
 228         * on max_io_len boundary.
 229         */
 230        bool split_discard_requests:1;
 231
 232        /*
 233         * Set if this target does not return zeroes on discarded blocks.
 234         */
 235        bool discard_zeroes_data_unsupported:1;
 236};
 237
 238/* Each target can link one of these into the table */
 239struct dm_target_callbacks {
 240        struct list_head list;
 241        int (*congested_fn) (struct dm_target_callbacks *, int);
 242};
 243
 244int dm_register_target(struct target_type *t);
 245void dm_unregister_target(struct target_type *t);
 246
 247/*
 248 * Target argument parsing.
 249 */
 250struct 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 */
 259struct 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 */
 269int 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 */
 277int 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 */
 283const char *dm_shift_arg(struct dm_arg_set *as);
 284
 285/*
 286 * Move through num_args arguments.
 287 */
 288void 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)
 299int dm_create(int minor, struct mapped_device **md);
 300
 301/*
 302 * Reference counting for md.
 303 */
 304struct mapped_device *dm_get_md(dev_t dev);
 305void dm_get(struct mapped_device *md);
 306void dm_put(struct mapped_device *md);
 307
 308/*
 309 * An arbitrary pointer may be stored alongside a mapped device.
 310 */
 311void dm_set_mdptr(struct mapped_device *md, void *ptr);
 312void *dm_get_mdptr(struct mapped_device *md);
 313
 314/*
 315 * A device can still be used while suspended, but I/O is deferred.
 316 */
 317int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 318int dm_resume(struct mapped_device *md);
 319
 320/*
 321 * Event functions.
 322 */
 323uint32_t dm_get_event_nr(struct mapped_device *md);
 324int dm_wait_event(struct mapped_device *md, int event_nr);
 325uint32_t dm_next_uevent_seq(struct mapped_device *md);
 326void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 327
 328/*
 329 * Info functions.
 330 */
 331const char *dm_device_name(struct mapped_device *md);
 332int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 333struct gendisk *dm_disk(struct mapped_device *md);
 334int dm_suspended(struct dm_target *ti);
 335int dm_noflush_suspending(struct dm_target *ti);
 336union map_info *dm_get_mapinfo(struct bio *bio);
 337union map_info *dm_get_rq_mapinfo(struct request *rq);
 338
 339/*
 340 * Geometry functions.
 341 */
 342int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 343int 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 */
 353int 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 */
 359int 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 */
 365void 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 */
 370int dm_table_complete(struct dm_table *t);
 371
 372/*
 373 * Target may require that it is never sent I/O larger than len.
 374 */
 375int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 376
 377/*
 378 * Table reference counting.
 379 */
 380struct dm_table *dm_get_live_table(struct mapped_device *md);
 381void dm_table_get(struct dm_table *t);
 382void dm_table_put(struct dm_table *t);
 383
 384/*
 385 * Queries
 386 */
 387sector_t dm_table_get_size(struct dm_table *t);
 388unsigned int dm_table_get_num_targets(struct dm_table *t);
 389fmode_t dm_table_get_mode(struct dm_table *t);
 390struct mapped_device *dm_table_get_md(struct dm_table *t);
 391
 392/*
 393 * Trigger an event.
 394 */
 395void 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 */
 401struct dm_table *dm_swap_table(struct mapped_device *md,
 402                               struct dm_table *t);
 403
 404/*
 405 * A wrapper around vmalloc.
 406 */
 407void *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
 415extern 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
 511static inline sector_t to_sector(unsigned long n)
 512{
 513        return (n >> SECTOR_SHIFT);
 514}
 515
 516static 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 *---------------------------------------------------------------*/
 524void dm_dispatch_request(struct request *rq);
 525void dm_requeue_unmapped_request(struct request *rq);
 526void dm_kill_unmapped_request(struct request *rq, int error);
 527int dm_underlying_device_busy(struct request_queue *q);
 528
 529#endif  /* _LINUX_DEVICE_MAPPER_H */
 530
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