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 };
  25
  26 /*
  27  * In the constructor the target parameter will already have the
  28  * table, type, begin and len fields filled in.
  29  */
  30 typedef int (*dm_ctr_fn) (struct dm_target *target,
  31                           unsigned int argc, char **argv);
  32
  33 /*
  34  * The destructor doesn't need to free the dm_target, just
  35  * anything hidden ti->private.
  36  */
  37 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  38
  39 /*
  40  * The map function must return:
  41  * < 0: error
  42  * = 0: The target will handle the io by resubmitting it later
  43  * = 1: simple remap complete
  44  * = 2: The target wants to push back the io
  45  */
  46 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
  47                           union map_info *map_context);
  48 typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone,
  49                                   union map_info *map_context);
  50
  51 /*
  52  * Returns:
  53  * < 0 : error (currently ignored)
  54  * 0   : ended successfully
  55  * 1   : for some reason the io has still not completed (eg,
  56  *       multipath target might want to requeue a failed io).
  57  * 2   : The target wants to push back the io
  58  */
  59 typedef int (*dm_endio_fn) (struct dm_target *ti,
  60                             struct bio *bio, int error,
  61                             union map_info *map_context);
  62 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
  63                                     struct request *clone, int error,
  64                                     union map_info *map_context);
  65
  66 typedef void (*dm_flush_fn) (struct dm_target *ti);
  67 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  68 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  69 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  70 typedef void (*dm_resume_fn) (struct dm_target *ti);
  71
  72 typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  73                              char *result, unsigned int maxlen);
  74
  75 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  76
  77 typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
  78                             unsigned long arg);
  79
  80 typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
  81                             struct bio_vec *biovec, int max_size);
  82
  83 /*
  84  * Returns:
  85  *    0: The target can handle the next I/O immediately.
  86  *    1: The target can't handle the next I/O immediately.
  87  */
  88 typedef int (*dm_busy_fn) (struct dm_target *ti);
  89
  90 void dm_error(const char *message);
  91
  92 /*
  93  * Combine device limits.
  94  */
  95 void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev);
  96
  97 struct dm_dev {
  98         struct block_device *bdev;
  99         fmode_t mode;
 100         char name[16];
 101 };
 102
 103 /*
 104  * Constructors should call these functions to ensure destination devices
 105  * are opened/closed correctly.
 106  * FIXME: too many arguments.
 107  */
 108 int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
 109                   sector_t len, fmode_t mode, struct dm_dev **result);
 110 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
 111
 112 /*
 113  * Information about a target type
 114  */
 115
 116 /*
 117  * Target features
 118  */
 119
 120 struct target_type {
 121         uint64_t features;
 122         const char *name;
 123         struct module *module;
 124         unsigned version[3];
 125         dm_ctr_fn ctr;
 126         dm_dtr_fn dtr;
 127         dm_map_fn map;
 128         dm_map_request_fn map_rq;
 129         dm_endio_fn end_io;
 130         dm_request_endio_fn rq_end_io;
 131         dm_flush_fn flush;
 132         dm_presuspend_fn presuspend;
 133         dm_postsuspend_fn postsuspend;
 134         dm_preresume_fn preresume;
 135         dm_resume_fn resume;
 136         dm_status_fn status;
 137         dm_message_fn message;
 138         dm_ioctl_fn ioctl;
 139         dm_merge_fn merge;
 140         dm_busy_fn busy;
 141
 142         /* For internal device-mapper use. */
 143         struct list_head list;
 144 };
 145
 146 struct io_restrictions {
 147         unsigned long bounce_pfn;
 148         unsigned long seg_boundary_mask;
 149         unsigned max_hw_sectors;
 150         unsigned max_sectors;
 151         unsigned max_segment_size;
 152         unsigned short hardsect_size;
 153         unsigned short max_hw_segments;
 154         unsigned short max_phys_segments;
 155         unsigned char no_cluster; /* inverted so that 0 is default */
 156 };
 157
 158 struct dm_target {
 159         struct dm_table *table;
 160         struct target_type *type;
 161
 162         /* target limits */
 163         sector_t begin;
 164         sector_t len;
 165
 166         /* FIXME: turn this into a mask, and merge with io_restrictions */
 167         /* Always a power of 2 */
 168         sector_t split_io;
 169
 170         /*
 171          * These are automatically filled in by
 172          * dm_table_get_device.
 173          */
 174         struct io_restrictions limits;
 175
 176         /* target specific data */
 177         void *private;
 178
 179         /* Used to provide an error string from the ctr */
 180         char *error;
 181 };
 182
 183 int dm_register_target(struct target_type *t);
 184 void dm_unregister_target(struct target_type *t);
 185
 186 /*-----------------------------------------------------------------
 187  * Functions for creating and manipulating mapped devices.
 188  * Drop the reference with dm_put when you finish with the object.
 189  *---------------------------------------------------------------*/
 190
 191 /*
 192  * DM_ANY_MINOR chooses the next available minor number.
 193  */
 194 #define DM_ANY_MINOR (-1)
 195 int dm_create(int minor, struct mapped_device **md);
 196
 197 /*
 198  * Reference counting for md.
 199  */
 200 struct mapped_device *dm_get_md(dev_t dev);
 201 void dm_get(struct mapped_device *md);
 202 void dm_put(struct mapped_device *md);
 203
 204 /*
 205  * An arbitrary pointer may be stored alongside a mapped device.
 206  */
 207 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 208 void *dm_get_mdptr(struct mapped_device *md);
 209
 210 /*
 211  * A device can still be used while suspended, but I/O is deferred.
 212  */
 213 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 214 int dm_resume(struct mapped_device *md);
 215
 216 /*
 217  * Event functions.
 218  */
 219 uint32_t dm_get_event_nr(struct mapped_device *md);
 220 int dm_wait_event(struct mapped_device *md, int event_nr);
 221 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 222 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 223
 224 /*
 225  * Info functions.
 226  */
 227 const char *dm_device_name(struct mapped_device *md);
 228 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 229 struct gendisk *dm_disk(struct mapped_device *md);
 230 int dm_suspended(struct mapped_device *md);
 231 int dm_noflush_suspending(struct dm_target *ti);
 232 union map_info *dm_get_mapinfo(struct bio *bio);
 233
 234 /*
 235  * Geometry functions.
 236  */
 237 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 238 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 239
 240
 241 /*-----------------------------------------------------------------
 242  * Functions for manipulating device-mapper tables.
 243  *---------------------------------------------------------------*/
 244
 245 /*
 246  * First create an empty table.
 247  */
 248 int dm_table_create(struct dm_table **result, fmode_t mode,
 249                     unsigned num_targets, struct mapped_device *md);
 250
 251 /*
 252  * Then call this once for each target.
 253  */
 254 int dm_table_add_target(struct dm_table *t, const char *type,
 255                         sector_t start, sector_t len, char *params);
 256
 257 /*
 258  * Finally call this to make the table ready for use.
 259  */
 260 int dm_table_complete(struct dm_table *t);
 261
 262 /*
 263  * Unplug all devices in a table.
 264  */
 265 void dm_table_unplug_all(struct dm_table *t);
 266
 267 /*
 268  * Table reference counting.
 269  */
 270 struct dm_table *dm_get_table(struct mapped_device *md);
 271 void dm_table_get(struct dm_table *t);
 272 void dm_table_put(struct dm_table *t);
 273
 274 /*
 275  * Queries
 276  */
 277 sector_t dm_table_get_size(struct dm_table *t);
 278 unsigned int dm_table_get_num_targets(struct dm_table *t);
 279 fmode_t dm_table_get_mode(struct dm_table *t);
 280 struct mapped_device *dm_table_get_md(struct dm_table *t);
 281
 282 /*
 283  * Trigger an event.
 284  */
 285 void dm_table_event(struct dm_table *t);
 286
 287 /*
 288  * The device must be suspended before calling this method.
 289  */
 290 int dm_swap_table(struct mapped_device *md, struct dm_table *t);
 291
 292 /*
 293  * A wrapper around vmalloc.
 294  */
 295 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 296
 297 /*-----------------------------------------------------------------
 298  * Macros.
 299  *---------------------------------------------------------------*/
 300 #define DM_NAME "device-mapper"
 301
 302 #define DMCRIT(f, arg...) \
 303         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 304
 305 #define DMERR(f, arg...) \
 306         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 307 #define DMERR_LIMIT(f, arg...) \
 308         do { \
 309                 if (printk_ratelimit()) \
 310                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 311                                f "\n", ## arg); \
 312         } while (0)
 313
 314 #define DMWARN(f, arg...) \
 315         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 316 #define DMWARN_LIMIT(f, arg...) \
 317         do { \
 318                 if (printk_ratelimit()) \
 319                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 320                                f "\n", ## arg); \
 321         } while (0)
 322
 323 #define DMINFO(f, arg...) \
 324         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 325 #define DMINFO_LIMIT(f, arg...) \
 326         do { \
 327                 if (printk_ratelimit()) \
 328                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 329                                "\n", ## arg); \
 330         } while (0)
 331
 332 #ifdef CONFIG_DM_DEBUG
 333 #  define DMDEBUG(f, arg...) \
 334         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 335 #  define DMDEBUG_LIMIT(f, arg...) \
 336         do { \
 337                 if (printk_ratelimit()) \
 338                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 339                                "\n", ## arg); \
 340         } while (0)
 341 #else
 342 #  define DMDEBUG(f, arg...) do {} while (0)
 343 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 344 #endif
 345
 346 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 347                           0 : scnprintf(result + sz, maxlen - sz, x))
 348
 349 #define SECTOR_SHIFT 9
 350
 351 /*
 352  * Definitions of return values from target end_io function.
 353  */
 354 #define DM_ENDIO_INCOMPLETE     1
 355 #define DM_ENDIO_REQUEUE        2
 356
 357 /*
 358  * Definitions of return values from target map function.
 359  */
 360 #define DM_MAPIO_SUBMITTED      0
 361 #define DM_MAPIO_REMAPPED       1
 362 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 363
 364 /*
 365  * Ceiling(n / sz)
 366  */
 367 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 368
 369 #define dm_sector_div_up(n, sz) ( \
 370 { \
 371         sector_t _r = ((n) + (sz) - 1); \
 372         sector_div(_r, (sz)); \
 373         _r; \
 374 } \
 375 )
 376
 377 /*
 378  * ceiling(n / size) * size
 379  */
 380 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 381
 382 #define dm_array_too_big(fixed, obj, num) \
 383         ((num) > (UINT_MAX - (fixed)) / (obj))
 384
 385 static inline sector_t to_sector(unsigned long n)
 386 {
 387         return (n >> SECTOR_SHIFT);
 388 }
 389
 390 static inline unsigned long to_bytes(sector_t n)
 391 {
 392         return (n << SECTOR_SHIFT);
 393 }
 394
 395 #endif  /* _LINUX_DEVICE_MAPPER_H */