linux/include/linux/device-mapper.h
<<
>>
Prefs
   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};
  27
  28/*
  29 * In the constructor the target parameter will already have the
  30 * table, type, begin and len fields filled in.
  31 */
  32typedef int (*dm_ctr_fn) (struct dm_target *target,
  33                          unsigned int argc, char **argv);
  34
  35/*
  36 * The destructor doesn't need to free the dm_target, just
  37 * anything hidden ti->private.
  38 */
  39typedef void (*dm_dtr_fn) (struct dm_target *ti);
  40
  41/*
  42 * The map function must return:
  43 * < 0: error
  44 * = 0: The target will handle the io by resubmitting it later
  45 * = 1: simple remap complete
  46 * = 2: The target wants to push back the io
  47 */
  48typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio);
  49typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone,
  50                                  union map_info *map_context);
  51
  52/*
  53 * Returns:
  54 * < 0 : error (currently ignored)
  55 * 0   : ended successfully
  56 * 1   : for some reason the io has still not completed (eg,
  57 *       multipath target might want to requeue a failed io).
  58 * 2   : The target wants to push back the io
  59 */
  60typedef int (*dm_endio_fn) (struct dm_target *ti,
  61                            struct bio *bio, int error);
  62typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  63                                    struct request *clone, int error,
  64                                    union map_info *map_context);
  65
  66typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  67typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  68typedef int (*dm_preresume_fn) (struct dm_target *ti);
  69typedef void (*dm_resume_fn) (struct dm_target *ti);
  70
  71typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  72                              unsigned status_flags, char *result, unsigned maxlen);
  73
  74typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  75
  76typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
  77                            unsigned long arg);
  78
  79typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
  80                            struct bio_vec *biovec, int max_size);
  81
  82typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
  83                                           struct dm_dev *dev,
  84                                           sector_t start, sector_t len,
  85                                           void *data);
  86
  87typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
  88                                      iterate_devices_callout_fn fn,
  89                                      void *data);
  90
  91typedef void (*dm_io_hints_fn) (struct dm_target *ti,
  92                                struct queue_limits *limits);
  93
  94/*
  95 * Returns:
  96 *    0: The target can handle the next I/O immediately.
  97 *    1: The target can't handle the next I/O immediately.
  98 */
  99typedef int (*dm_busy_fn) (struct dm_target *ti);
 100
 101void dm_error(const char *message);
 102
 103/*
 104 * Combine device limits.
 105 */
 106int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 107                         sector_t start, sector_t len, void *data);
 108
 109struct dm_dev {
 110        struct block_device *bdev;
 111        fmode_t mode;
 112        char name[16];
 113};
 114
 115/*
 116 * Constructors should call these functions to ensure destination devices
 117 * are opened/closed correctly.
 118 */
 119int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
 120                                                 struct dm_dev **result);
 121void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 122
 123/*
 124 * Information about a target type
 125 */
 126
 127struct target_type {
 128        uint64_t features;
 129        const char *name;
 130        struct module *module;
 131        unsigned version[3];
 132        dm_ctr_fn ctr;
 133        dm_dtr_fn dtr;
 134        dm_map_fn map;
 135        dm_map_request_fn map_rq;
 136        dm_endio_fn end_io;
 137        dm_request_endio_fn rq_end_io;
 138        dm_presuspend_fn presuspend;
 139        dm_postsuspend_fn postsuspend;
 140        dm_preresume_fn preresume;
 141        dm_resume_fn resume;
 142        dm_status_fn status;
 143        dm_message_fn message;
 144        dm_ioctl_fn ioctl;
 145        dm_merge_fn merge;
 146        dm_busy_fn busy;
 147        dm_iterate_devices_fn iterate_devices;
 148        dm_io_hints_fn io_hints;
 149
 150        /* For internal device-mapper use. */
 151        struct list_head list;
 152};
 153
 154/*
 155 * Target features
 156 */
 157
 158/*
 159 * Any table that contains an instance of this target must have only one.
 160 */
 161#define DM_TARGET_SINGLETON             0x00000001
 162#define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
 163
 164/*
 165 * Indicates that a target does not support read-only devices.
 166 */
 167#define DM_TARGET_ALWAYS_WRITEABLE      0x00000002
 168#define dm_target_always_writeable(type) \
 169                ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
 170
 171/*
 172 * Any device that contains a table with an instance of this target may never
 173 * have tables containing any different target type.
 174 */
 175#define DM_TARGET_IMMUTABLE             0x00000004
 176#define dm_target_is_immutable(type)    ((type)->features & DM_TARGET_IMMUTABLE)
 177
 178struct dm_target {
 179        struct dm_table *table;
 180        struct target_type *type;
 181
 182        /* target limits */
 183        sector_t begin;
 184        sector_t len;
 185
 186        /* If non-zero, maximum size of I/O submitted to a target. */
 187        uint32_t max_io_len;
 188
 189        /*
 190         * A number of zero-length barrier requests that will be submitted
 191         * to the target for the purpose of flushing cache.
 192         *
 193         * The request number can be accessed with dm_bio_get_target_request_nr.
 194         * It is a responsibility of the target driver to remap these requests
 195         * to the real underlying devices.
 196         */
 197        unsigned num_flush_requests;
 198
 199        /*
 200         * The number of discard requests that will be submitted to the target.
 201         * The request number can be accessed with dm_bio_get_target_request_nr.
 202         */
 203        unsigned num_discard_requests;
 204
 205        /*
 206         * The number of WRITE SAME requests that will be submitted to the target.
 207         * The request number can be accessed with dm_bio_get_target_request_nr.
 208         */
 209        unsigned num_write_same_requests;
 210
 211        /*
 212         * The minimum number of extra bytes allocated in each bio for the
 213         * target to use.  dm_per_bio_data returns the data location.
 214         */
 215        unsigned per_bio_data_size;
 216
 217        /* target specific data */
 218        void *private;
 219
 220        /* Used to provide an error string from the ctr */
 221        char *error;
 222
 223        /*
 224         * Set if this target needs to receive flushes regardless of
 225         * whether or not its underlying devices have support.
 226         */
 227        bool flush_supported:1;
 228
 229        /*
 230         * Set if this target needs to receive discards regardless of
 231         * whether or not its underlying devices have support.
 232         */
 233        bool discards_supported:1;
 234
 235        /*
 236         * Set if the target required discard request to be split
 237         * on max_io_len boundary.
 238         */
 239        bool split_discard_requests:1;
 240
 241        /*
 242         * Set if this target does not return zeroes on discarded blocks.
 243         */
 244        bool discard_zeroes_data_unsupported:1;
 245};
 246
 247/* Each target can link one of these into the table */
 248struct dm_target_callbacks {
 249        struct list_head list;
 250        int (*congested_fn) (struct dm_target_callbacks *, int);
 251};
 252
 253/*
 254 * For bio-based dm.
 255 * One of these is allocated for each bio.
 256 * This structure shouldn't be touched directly by target drivers.
 257 * It is here so that we can inline dm_per_bio_data and
 258 * dm_bio_from_per_bio_data
 259 */
 260struct dm_target_io {
 261        struct dm_io *io;
 262        struct dm_target *ti;
 263        union map_info info;
 264        unsigned target_request_nr;
 265        struct bio clone;
 266};
 267
 268static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
 269{
 270        return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
 271}
 272
 273static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
 274{
 275        return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
 276}
 277
 278static inline unsigned dm_bio_get_target_request_nr(const struct bio *bio)
 279{
 280        return container_of(bio, struct dm_target_io, clone)->target_request_nr;
 281}
 282
 283int dm_register_target(struct target_type *t);
 284void dm_unregister_target(struct target_type *t);
 285
 286/*
 287 * Target argument parsing.
 288 */
 289struct dm_arg_set {
 290        unsigned argc;
 291        char **argv;
 292};
 293
 294/*
 295 * The minimum and maximum value of a numeric argument, together with
 296 * the error message to use if the number is found to be outside that range.
 297 */
 298struct dm_arg {
 299        unsigned min;
 300        unsigned max;
 301        char *error;
 302};
 303
 304/*
 305 * Validate the next argument, either returning it as *value or, if invalid,
 306 * returning -EINVAL and setting *error.
 307 */
 308int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
 309                unsigned *value, char **error);
 310
 311/*
 312 * Process the next argument as the start of a group containing between
 313 * arg->min and arg->max further arguments. Either return the size as
 314 * *num_args or, if invalid, return -EINVAL and set *error.
 315 */
 316int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
 317                      unsigned *num_args, char **error);
 318
 319/*
 320 * Return the current argument and shift to the next.
 321 */
 322const char *dm_shift_arg(struct dm_arg_set *as);
 323
 324/*
 325 * Move through num_args arguments.
 326 */
 327void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
 328
 329/*-----------------------------------------------------------------
 330 * Functions for creating and manipulating mapped devices.
 331 * Drop the reference with dm_put when you finish with the object.
 332 *---------------------------------------------------------------*/
 333
 334/*
 335 * DM_ANY_MINOR chooses the next available minor number.
 336 */
 337#define DM_ANY_MINOR (-1)
 338int dm_create(int minor, struct mapped_device **md);
 339
 340/*
 341 * Reference counting for md.
 342 */
 343struct mapped_device *dm_get_md(dev_t dev);
 344void dm_get(struct mapped_device *md);
 345void dm_put(struct mapped_device *md);
 346
 347/*
 348 * An arbitrary pointer may be stored alongside a mapped device.
 349 */
 350void dm_set_mdptr(struct mapped_device *md, void *ptr);
 351void *dm_get_mdptr(struct mapped_device *md);
 352
 353/*
 354 * A device can still be used while suspended, but I/O is deferred.
 355 */
 356int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 357int dm_resume(struct mapped_device *md);
 358
 359/*
 360 * Event functions.
 361 */
 362uint32_t dm_get_event_nr(struct mapped_device *md);
 363int dm_wait_event(struct mapped_device *md, int event_nr);
 364uint32_t dm_next_uevent_seq(struct mapped_device *md);
 365void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 366
 367/*
 368 * Info functions.
 369 */
 370const char *dm_device_name(struct mapped_device *md);
 371int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 372struct gendisk *dm_disk(struct mapped_device *md);
 373int dm_suspended(struct dm_target *ti);
 374int dm_noflush_suspending(struct dm_target *ti);
 375union map_info *dm_get_mapinfo(struct bio *bio);
 376union map_info *dm_get_rq_mapinfo(struct request *rq);
 377
 378/*
 379 * Geometry functions.
 380 */
 381int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 382int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 383
 384
 385/*-----------------------------------------------------------------
 386 * Functions for manipulating device-mapper tables.
 387 *---------------------------------------------------------------*/
 388
 389/*
 390 * First create an empty table.
 391 */
 392int dm_table_create(struct dm_table **result, fmode_t mode,
 393                    unsigned num_targets, struct mapped_device *md);
 394
 395/*
 396 * Then call this once for each target.
 397 */
 398int dm_table_add_target(struct dm_table *t, const char *type,
 399                        sector_t start, sector_t len, char *params);
 400
 401/*
 402 * Target_ctr should call this if it needs to add any callbacks.
 403 */
 404void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
 405
 406/*
 407 * Finally call this to make the table ready for use.
 408 */
 409int dm_table_complete(struct dm_table *t);
 410
 411/*
 412 * Target may require that it is never sent I/O larger than len.
 413 */
 414int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
 415
 416/*
 417 * Table reference counting.
 418 */
 419struct dm_table *dm_get_live_table(struct mapped_device *md);
 420void dm_table_get(struct dm_table *t);
 421void dm_table_put(struct dm_table *t);
 422
 423/*
 424 * Queries
 425 */
 426sector_t dm_table_get_size(struct dm_table *t);
 427unsigned int dm_table_get_num_targets(struct dm_table *t);
 428fmode_t dm_table_get_mode(struct dm_table *t);
 429struct mapped_device *dm_table_get_md(struct dm_table *t);
 430
 431/*
 432 * Trigger an event.
 433 */
 434void dm_table_event(struct dm_table *t);
 435
 436/*
 437 * The device must be suspended before calling this method.
 438 * Returns the previous table, which the caller must destroy.
 439 */
 440struct dm_table *dm_swap_table(struct mapped_device *md,
 441                               struct dm_table *t);
 442
 443/*
 444 * A wrapper around vmalloc.
 445 */
 446void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 447
 448/*-----------------------------------------------------------------
 449 * Macros.
 450 *---------------------------------------------------------------*/
 451#define DM_NAME "device-mapper"
 452
 453#ifdef CONFIG_PRINTK
 454extern struct ratelimit_state dm_ratelimit_state;
 455
 456#define dm_ratelimit()  __ratelimit(&dm_ratelimit_state)
 457#else
 458#define dm_ratelimit()  0
 459#endif
 460
 461#define DMCRIT(f, arg...) \
 462        printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 463
 464#define DMERR(f, arg...) \
 465        printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 466#define DMERR_LIMIT(f, arg...) \
 467        do { \
 468                if (dm_ratelimit())     \
 469                        printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 470                               f "\n", ## arg); \
 471        } while (0)
 472
 473#define DMWARN(f, arg...) \
 474        printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 475#define DMWARN_LIMIT(f, arg...) \
 476        do { \
 477                if (dm_ratelimit())     \
 478                        printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 479                               f "\n", ## arg); \
 480        } while (0)
 481
 482#define DMINFO(f, arg...) \
 483        printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 484#define DMINFO_LIMIT(f, arg...) \
 485        do { \
 486                if (dm_ratelimit())     \
 487                        printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 488                               "\n", ## arg); \
 489        } while (0)
 490
 491#ifdef CONFIG_DM_DEBUG
 492#  define DMDEBUG(f, arg...) \
 493        printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 494#  define DMDEBUG_LIMIT(f, arg...) \
 495        do { \
 496                if (dm_ratelimit())     \
 497                        printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 498                               "\n", ## arg); \
 499        } while (0)
 500#else
 501#  define DMDEBUG(f, arg...) do {} while (0)
 502#  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 503#endif
 504
 505#define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 506                          0 : scnprintf(result + sz, maxlen - sz, x))
 507
 508#define SECTOR_SHIFT 9
 509
 510/*
 511 * Definitions of return values from target end_io function.
 512 */
 513#define DM_ENDIO_INCOMPLETE     1
 514#define DM_ENDIO_REQUEUE        2
 515
 516/*
 517 * Definitions of return values from target map function.
 518 */
 519#define DM_MAPIO_SUBMITTED      0
 520#define DM_MAPIO_REMAPPED       1
 521#define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 522
 523/*
 524 * Ceiling(n / sz)
 525 */
 526#define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 527
 528#define dm_sector_div_up(n, sz) ( \
 529{ \
 530        sector_t _r = ((n) + (sz) - 1); \
 531        sector_div(_r, (sz)); \
 532        _r; \
 533} \
 534)
 535
 536/*
 537 * ceiling(n / size) * size
 538 */
 539#define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 540
 541#define dm_array_too_big(fixed, obj, num) \
 542        ((num) > (UINT_MAX - (fixed)) / (obj))
 543
 544/*
 545 * Sector offset taken relative to the start of the target instead of
 546 * relative to the start of the device.
 547 */
 548#define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
 549
 550static inline sector_t to_sector(unsigned long n)
 551{
 552        return (n >> SECTOR_SHIFT);
 553}
 554
 555static inline unsigned long to_bytes(sector_t n)
 556{
 557        return (n << SECTOR_SHIFT);
 558}
 559
 560/*-----------------------------------------------------------------
 561 * Helper for block layer and dm core operations
 562 *---------------------------------------------------------------*/
 563void dm_dispatch_request(struct request *rq);
 564void dm_requeue_unmapped_request(struct request *rq);
 565void dm_kill_unmapped_request(struct request *rq, int error);
 566int dm_underlying_device_busy(struct request_queue *q);
 567
 568#endif  /* _LINUX_DEVICE_MAPPER_H */
 569
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.