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 #define DM_TARGET_SUPPORTS_BARRIERS 0x00000001
 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 hardsect_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          * These are automatically filled in by
 173          * dm_table_get_device.
 174          */
 175         struct io_restrictions limits;
 176
 177         /* target specific data */
 178         void *private;
 179
 180         /* Used to provide an error string from the ctr */
 181         char *error;
 182 };
 183
 184 int dm_register_target(struct target_type *t);
 185 void dm_unregister_target(struct target_type *t);
 186
 187 /*-----------------------------------------------------------------
 188  * Functions for creating and manipulating mapped devices.
 189  * Drop the reference with dm_put when you finish with the object.
 190  *---------------------------------------------------------------*/
 191
 192 /*
 193  * DM_ANY_MINOR chooses the next available minor number.
 194  */
 195 #define DM_ANY_MINOR (-1)
 196 int dm_create(int minor, struct mapped_device **md);
 197
 198 /*
 199  * Reference counting for md.
 200  */
 201 struct mapped_device *dm_get_md(dev_t dev);
 202 void dm_get(struct mapped_device *md);
 203 void dm_put(struct mapped_device *md);
 204
 205 /*
 206  * An arbitrary pointer may be stored alongside a mapped device.
 207  */
 208 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 209 void *dm_get_mdptr(struct mapped_device *md);
 210
 211 /*
 212  * A device can still be used while suspended, but I/O is deferred.
 213  */
 214 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 215 int dm_resume(struct mapped_device *md);
 216
 217 /*
 218  * Event functions.
 219  */
 220 uint32_t dm_get_event_nr(struct mapped_device *md);
 221 int dm_wait_event(struct mapped_device *md, int event_nr);
 222 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 223 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 224
 225 /*
 226  * Info functions.
 227  */
 228 const char *dm_device_name(struct mapped_device *md);
 229 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 230 struct gendisk *dm_disk(struct mapped_device *md);
 231 int dm_suspended(struct mapped_device *md);
 232 int dm_noflush_suspending(struct dm_target *ti);
 233 union map_info *dm_get_mapinfo(struct bio *bio);
 234
 235 /*
 236  * Geometry functions.
 237  */
 238 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 239 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 240
 241
 242 /*-----------------------------------------------------------------
 243  * Functions for manipulating device-mapper tables.
 244  *---------------------------------------------------------------*/
 245
 246 /*
 247  * First create an empty table.
 248  */
 249 int dm_table_create(struct dm_table **result, fmode_t mode,
 250                     unsigned num_targets, struct mapped_device *md);
 251
 252 /*
 253  * Then call this once for each target.
 254  */
 255 int dm_table_add_target(struct dm_table *t, const char *type,
 256                         sector_t start, sector_t len, char *params);
 257
 258 /*
 259  * Finally call this to make the table ready for use.
 260  */
 261 int dm_table_complete(struct dm_table *t);
 262
 263 /*
 264  * Unplug all devices in a table.
 265  */
 266 void dm_table_unplug_all(struct dm_table *t);
 267
 268 /*
 269  * Table reference counting.
 270  */
 271 struct dm_table *dm_get_table(struct mapped_device *md);
 272 void dm_table_get(struct dm_table *t);
 273 void dm_table_put(struct dm_table *t);
 274
 275 /*
 276  * Queries
 277  */
 278 sector_t dm_table_get_size(struct dm_table *t);
 279 unsigned int dm_table_get_num_targets(struct dm_table *t);
 280 fmode_t dm_table_get_mode(struct dm_table *t);
 281 struct mapped_device *dm_table_get_md(struct dm_table *t);
 282
 283 /*
 284  * Trigger an event.
 285  */
 286 void dm_table_event(struct dm_table *t);
 287
 288 /*
 289  * The device must be suspended before calling this method.
 290  */
 291 int dm_swap_table(struct mapped_device *md, struct dm_table *t);
 292
 293 /*
 294  * A wrapper around vmalloc.
 295  */
 296 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 297
 298 /*-----------------------------------------------------------------
 299  * Macros.
 300  *---------------------------------------------------------------*/
 301 #define DM_NAME "device-mapper"
 302
 303 #define DMCRIT(f, arg...) \
 304         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 305
 306 #define DMERR(f, arg...) \
 307         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 308 #define DMERR_LIMIT(f, arg...) \
 309         do { \
 310                 if (printk_ratelimit()) \
 311                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 312                                f "\n", ## arg); \
 313         } while (0)
 314
 315 #define DMWARN(f, arg...) \
 316         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 317 #define DMWARN_LIMIT(f, arg...) \
 318         do { \
 319                 if (printk_ratelimit()) \
 320                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 321                                f "\n", ## arg); \
 322         } while (0)
 323
 324 #define DMINFO(f, arg...) \
 325         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 326 #define DMINFO_LIMIT(f, arg...) \
 327         do { \
 328                 if (printk_ratelimit()) \
 329                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 330                                "\n", ## arg); \
 331         } while (0)
 332
 333 #ifdef CONFIG_DM_DEBUG
 334 #  define DMDEBUG(f, arg...) \
 335         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 336 #  define DMDEBUG_LIMIT(f, arg...) \
 337         do { \
 338                 if (printk_ratelimit()) \
 339                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 340                                "\n", ## arg); \
 341         } while (0)
 342 #else
 343 #  define DMDEBUG(f, arg...) do {} while (0)
 344 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 345 #endif
 346
 347 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 348                           0 : scnprintf(result + sz, maxlen - sz, x))
 349
 350 #define SECTOR_SHIFT 9
 351
 352 /*
 353  * Definitions of return values from target end_io function.
 354  */
 355 #define DM_ENDIO_INCOMPLETE     1
 356 #define DM_ENDIO_REQUEUE        2
 357
 358 /*
 359  * Definitions of return values from target map function.
 360  */
 361 #define DM_MAPIO_SUBMITTED      0
 362 #define DM_MAPIO_REMAPPED       1
 363 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 364
 365 /*
 366  * Ceiling(n / sz)
 367  */
 368 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 369
 370 #define dm_sector_div_up(n, sz) ( \
 371 { \
 372         sector_t _r = ((n) + (sz) - 1); \
 373         sector_div(_r, (sz)); \
 374         _r; \
 375 } \
 376 )
 377
 378 /*
 379  * ceiling(n / size) * size
 380  */
 381 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 382
 383 #define dm_array_too_big(fixed, obj, num) \
 384         ((num) > (UINT_MAX - (fixed)) / (obj))
 385
 386 static inline sector_t to_sector(unsigned long n)
 387 {
 388         return (n >> SECTOR_SHIFT);
 389 }
 390
 391 static inline unsigned long to_bytes(sector_t n)
 392 {
 393         return (n << SECTOR_SHIFT);
 394 }
 395
 396 #endif  /* _LINUX_DEVICE_MAPPER_H */