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
  14 struct dm_target;
  15 struct dm_table;
  16 struct mapped_device;
  17 struct bio_vec;
  18
  19 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  20
  21 union map_info {
  22         void *ptr;
  23         unsigned long long ll;
  24         unsigned flush_request;
  25 };
  26
  27 /*
  28  * In the constructor the target parameter will already have the
  29  * table, type, begin and len fields filled in.
  30  */
  31 typedef int (*dm_ctr_fn) (struct dm_target *target,
  32                           unsigned int argc, char **argv);
  33
  34 /*
  35  * The destructor doesn't need to free the dm_target, just
  36  * anything hidden ti->private.
  37  */
  38 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  39
  40 /*
  41  * The map function must return:
  42  * < 0: error
  43  * = 0: The target will handle the io by resubmitting it later
  44  * = 1: simple remap complete
  45  * = 2: The target wants to push back the io
  46  */
  47 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
  48                           union map_info *map_context);
  49 typedef 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  */
  60 typedef int (*dm_endio_fn) (struct dm_target *ti,
  61                             struct bio *bio, int error,
  62                             union map_info *map_context);
  63 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  64                                     struct request *clone, int error,
  65                                     union map_info *map_context);
  66
  67 typedef void (*dm_flush_fn) (struct dm_target *ti);
  68 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  69 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  70 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  71 typedef void (*dm_resume_fn) (struct dm_target *ti);
  72
  73 typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  74                              char *result, unsigned int maxlen);
  75
  76 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  77
  78 typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
  79                             unsigned long arg);
  80
  81 typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
  82                             struct bio_vec *biovec, int max_size);
  83
  84 /*
  85  * Returns:
  86  *    0: The target can handle the next I/O immediately.
  87  *    1: The target can't handle the next I/O immediately.
  88  */
  89 typedef int (*dm_busy_fn) (struct dm_target *ti);
  90
  91 void dm_error(const char *message);
  92
  93 /*
  94  * Combine device limits.
  95  */
  96 void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev);
  97
  98 struct dm_dev {
  99         struct block_device *bdev;
 100         fmode_t mode;
 101         char name[16];
 102 };
 103
 104 /*
 105  * Constructors should call these functions to ensure destination devices
 106  * are opened/closed correctly.
 107  * FIXME: too many arguments.
 108  */
 109 int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
 110                   sector_t len, fmode_t mode, struct dm_dev **result);
 111 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 112
 113 /*
 114  * Information about a target type
 115  */
 116
 117 /*
 118  * Target features
 119  */
 120
 121 struct target_type {
 122         uint64_t features;
 123         const char *name;
 124         struct module *module;
 125         unsigned version[3];
 126         dm_ctr_fn ctr;
 127         dm_dtr_fn dtr;
 128         dm_map_fn map;
 129         dm_map_request_fn map_rq;
 130         dm_endio_fn end_io;
 131         dm_request_endio_fn rq_end_io;
 132         dm_flush_fn flush;
 133         dm_presuspend_fn presuspend;
 134         dm_postsuspend_fn postsuspend;
 135         dm_preresume_fn preresume;
 136         dm_resume_fn resume;
 137         dm_status_fn status;
 138         dm_message_fn message;
 139         dm_ioctl_fn ioctl;
 140         dm_merge_fn merge;
 141         dm_busy_fn busy;
 142
 143         /* For internal device-mapper use. */
 144         struct list_head list;
 145 };
 146
 147 struct io_restrictions {
 148         unsigned long bounce_pfn;
 149         unsigned long seg_boundary_mask;
 150         unsigned max_hw_sectors;
 151         unsigned max_sectors;
 152         unsigned max_segment_size;
 153         unsigned short logical_block_size;
 154         unsigned short max_hw_segments;
 155         unsigned short max_phys_segments;
 156         unsigned char no_cluster; /* inverted so that 0 is default */
 157 };
 158
 159 struct dm_target {
 160         struct dm_table *table;
 161         struct target_type *type;
 162
 163         /* target limits */
 164         sector_t begin;
 165         sector_t len;
 166
 167         /* FIXME: turn this into a mask, and merge with io_restrictions */
 168         /* Always a power of 2 */
 169         sector_t split_io;
 170
 171         /*
 172          * A number of zero-length barrier requests that will be submitted
 173          * to the target for the purpose of flushing cache.
 174          *
 175          * The request number will be placed in union map_info->flush_request.
 176          * It is a responsibility of the target driver to remap these requests
 177          * to the real underlying devices.
 178          */
 179         unsigned num_flush_requests;
 180
 181         /*
 182          * These are automatically filled in by
 183          * dm_table_get_device.
 184          */
 185         struct io_restrictions limits;
 186
 187         /* target specific data */
 188         void *private;
 189
 190         /* Used to provide an error string from the ctr */
 191         char *error;
 192 };
 193
 194 int dm_register_target(struct target_type *t);
 195 void dm_unregister_target(struct target_type *t);
 196
 197 /*-----------------------------------------------------------------
 198  * Functions for creating and manipulating mapped devices.
 199  * Drop the reference with dm_put when you finish with the object.
 200  *---------------------------------------------------------------*/
 201
 202 /*
 203  * DM_ANY_MINOR chooses the next available minor number.
 204  */
 205 #define DM_ANY_MINOR (-1)
 206 int dm_create(int minor, struct mapped_device **md);
 207
 208 /*
 209  * Reference counting for md.
 210  */
 211 struct mapped_device *dm_get_md(dev_t dev);
 212 void dm_get(struct mapped_device *md);
 213 void dm_put(struct mapped_device *md);
 214
 215 /*
 216  * An arbitrary pointer may be stored alongside a mapped device.
 217  */
 218 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 219 void *dm_get_mdptr(struct mapped_device *md);
 220
 221 /*
 222  * A device can still be used while suspended, but I/O is deferred.
 223  */
 224 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 225 int dm_resume(struct mapped_device *md);
 226
 227 /*
 228  * Event functions.
 229  */
 230 uint32_t dm_get_event_nr(struct mapped_device *md);
 231 int dm_wait_event(struct mapped_device *md, int event_nr);
 232 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 233 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 234
 235 /*
 236  * Info functions.
 237  */
 238 const char *dm_device_name(struct mapped_device *md);
 239 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 240 struct gendisk *dm_disk(struct mapped_device *md);
 241 int dm_suspended(struct mapped_device *md);
 242 int dm_noflush_suspending(struct dm_target *ti);
 243 union map_info *dm_get_mapinfo(struct bio *bio);
 244
 245 /*
 246  * Geometry functions.
 247  */
 248 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 249 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 250
 251
 252 /*-----------------------------------------------------------------
 253  * Functions for manipulating device-mapper tables.
 254  *---------------------------------------------------------------*/
 255
 256 /*
 257  * First create an empty table.
 258  */
 259 int dm_table_create(struct dm_table **result, fmode_t mode,
 260                     unsigned num_targets, struct mapped_device *md);
 261
 262 /*
 263  * Then call this once for each target.
 264  */
 265 int dm_table_add_target(struct dm_table *t, const char *type,
 266                         sector_t start, sector_t len, char *params);
 267
 268 /*
 269  * Finally call this to make the table ready for use.
 270  */
 271 int dm_table_complete(struct dm_table *t);
 272
 273 /*
 274  * Unplug all devices in a table.
 275  */
 276 void dm_table_unplug_all(struct dm_table *t);
 277
 278 /*
 279  * Table reference counting.
 280  */
 281 struct dm_table *dm_get_table(struct mapped_device *md);
 282 void dm_table_get(struct dm_table *t);
 283 void dm_table_put(struct dm_table *t);
 284
 285 /*
 286  * Queries
 287  */
 288 sector_t dm_table_get_size(struct dm_table *t);
 289 unsigned int dm_table_get_num_targets(struct dm_table *t);
 290 fmode_t dm_table_get_mode(struct dm_table *t);
 291 struct mapped_device *dm_table_get_md(struct dm_table *t);
 292
 293 /*
 294  * Trigger an event.
 295  */
 296 void dm_table_event(struct dm_table *t);
 297
 298 /*
 299  * The device must be suspended before calling this method.
 300  */
 301 int dm_swap_table(struct mapped_device *md, struct dm_table *t);
 302
 303 /*
 304  * A wrapper around vmalloc.
 305  */
 306 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 307
 308 /*-----------------------------------------------------------------
 309  * Macros.
 310  *---------------------------------------------------------------*/
 311 #define DM_NAME "device-mapper"
 312
 313 #define DMCRIT(f, arg...) \
 314         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 315
 316 #define DMERR(f, arg...) \
 317         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 318 #define DMERR_LIMIT(f, arg...) \
 319         do { \
 320                 if (printk_ratelimit()) \
 321                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 322                                f "\n", ## arg); \
 323         } while (0)
 324
 325 #define DMWARN(f, arg...) \
 326         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 327 #define DMWARN_LIMIT(f, arg...) \
 328         do { \
 329                 if (printk_ratelimit()) \
 330                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 331                                f "\n", ## arg); \
 332         } while (0)
 333
 334 #define DMINFO(f, arg...) \
 335         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 336 #define DMINFO_LIMIT(f, arg...) \
 337         do { \
 338                 if (printk_ratelimit()) \
 339                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 340                                "\n", ## arg); \
 341         } while (0)
 342
 343 #ifdef CONFIG_DM_DEBUG
 344 #  define DMDEBUG(f, arg...) \
 345         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 346 #  define DMDEBUG_LIMIT(f, arg...) \
 347         do { \
 348                 if (printk_ratelimit()) \
 349                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 350                                "\n", ## arg); \
 351         } while (0)
 352 #else
 353 #  define DMDEBUG(f, arg...) do {} while (0)
 354 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 355 #endif
 356
 357 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 358                           0 : scnprintf(result + sz, maxlen - sz, x))
 359
 360 #define SECTOR_SHIFT 9
 361
 362 /*
 363  * Definitions of return values from target end_io function.
 364  */
 365 #define DM_ENDIO_INCOMPLETE     1
 366 #define DM_ENDIO_REQUEUE        2
 367
 368 /*
 369  * Definitions of return values from target map function.
 370  */
 371 #define DM_MAPIO_SUBMITTED      0
 372 #define DM_MAPIO_REMAPPED       1
 373 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 374
 375 /*
 376  * Ceiling(n / sz)
 377  */
 378 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 379
 380 #define dm_sector_div_up(n, sz) ( \
 381 { \
 382         sector_t _r = ((n) + (sz) - 1); \
 383         sector_div(_r, (sz)); \
 384         _r; \
 385 } \
 386 )
 387
 388 /*
 389  * ceiling(n / size) * size
 390  */
 391 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 392
 393 #define dm_array_too_big(fixed, obj, num) \
 394         ((num) > (UINT_MAX - (fixed)) / (obj))
 395
 396 static inline sector_t to_sector(unsigned long n)
 397 {
 398         return (n >> SECTOR_SHIFT);
 399 }
 400
 401 static inline unsigned long to_bytes(sector_t n)
 402 {
 403         return (n << SECTOR_SHIFT);
 404 }
 405
 406 #endif  /* _LINUX_DEVICE_MAPPER_H */