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
 144 struct io_restrictions {
 145         unsigned long bounce_pfn;
 146         unsigned long seg_boundary_mask;
 147         unsigned max_hw_sectors;
 148         unsigned max_sectors;
 149         unsigned max_segment_size;
 150         unsigned short hardsect_size;
 151         unsigned short max_hw_segments;
 152         unsigned short max_phys_segments;
 153         unsigned char no_cluster; /* inverted so that 0 is default */
 154 };
 155
 156 struct dm_target {
 157         struct dm_table *table;
 158         struct target_type *type;
 159
 160         /* target limits */
 161         sector_t begin;
 162         sector_t len;
 163
 164         /* FIXME: turn this into a mask, and merge with io_restrictions */
 165         /* Always a power of 2 */
 166         sector_t split_io;
 167
 168         /*
 169          * These are automatically filled in by
 170          * dm_table_get_device.
 171          */
 172         struct io_restrictions limits;
 173
 174         /* target specific data */
 175         void *private;
 176
 177         /* Used to provide an error string from the ctr */
 178         char *error;
 179 };
 180
 181 int dm_register_target(struct target_type *t);
 182 void dm_unregister_target(struct target_type *t);
 183
 184 /*-----------------------------------------------------------------
 185  * Functions for creating and manipulating mapped devices.
 186  * Drop the reference with dm_put when you finish with the object.
 187  *---------------------------------------------------------------*/
 188
 189 /*
 190  * DM_ANY_MINOR chooses the next available minor number.
 191  */
 192 #define DM_ANY_MINOR (-1)
 193 int dm_create(int minor, struct mapped_device **md);
 194
 195 /*
 196  * Reference counting for md.
 197  */
 198 struct mapped_device *dm_get_md(dev_t dev);
 199 void dm_get(struct mapped_device *md);
 200 void dm_put(struct mapped_device *md);
 201
 202 /*
 203  * An arbitrary pointer may be stored alongside a mapped device.
 204  */
 205 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 206 void *dm_get_mdptr(struct mapped_device *md);
 207
 208 /*
 209  * A device can still be used while suspended, but I/O is deferred.
 210  */
 211 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 212 int dm_resume(struct mapped_device *md);
 213
 214 /*
 215  * Event functions.
 216  */
 217 uint32_t dm_get_event_nr(struct mapped_device *md);
 218 int dm_wait_event(struct mapped_device *md, int event_nr);
 219 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 220 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 221
 222 /*
 223  * Info functions.
 224  */
 225 const char *dm_device_name(struct mapped_device *md);
 226 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 227 struct gendisk *dm_disk(struct mapped_device *md);
 228 int dm_suspended(struct mapped_device *md);
 229 int dm_noflush_suspending(struct dm_target *ti);
 230 union map_info *dm_get_mapinfo(struct bio *bio);
 231
 232 /*
 233  * Geometry functions.
 234  */
 235 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 236 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 237
 238
 239 /*-----------------------------------------------------------------
 240  * Functions for manipulating device-mapper tables.
 241  *---------------------------------------------------------------*/
 242
 243 /*
 244  * First create an empty table.
 245  */
 246 int dm_table_create(struct dm_table **result, fmode_t mode,
 247                     unsigned num_targets, struct mapped_device *md);
 248
 249 /*
 250  * Then call this once for each target.
 251  */
 252 int dm_table_add_target(struct dm_table *t, const char *type,
 253                         sector_t start, sector_t len, char *params);
 254
 255 /*
 256  * Finally call this to make the table ready for use.
 257  */
 258 int dm_table_complete(struct dm_table *t);
 259
 260 /*
 261  * Unplug all devices in a table.
 262  */
 263 void dm_table_unplug_all(struct dm_table *t);
 264
 265 /*
 266  * Table reference counting.
 267  */
 268 struct dm_table *dm_get_table(struct mapped_device *md);
 269 void dm_table_get(struct dm_table *t);
 270 void dm_table_put(struct dm_table *t);
 271
 272 /*
 273  * Queries
 274  */
 275 sector_t dm_table_get_size(struct dm_table *t);
 276 unsigned int dm_table_get_num_targets(struct dm_table *t);
 277 fmode_t dm_table_get_mode(struct dm_table *t);
 278 struct mapped_device *dm_table_get_md(struct dm_table *t);
 279
 280 /*
 281  * Trigger an event.
 282  */
 283 void dm_table_event(struct dm_table *t);
 284
 285 /*
 286  * The device must be suspended before calling this method.
 287  */
 288 int dm_swap_table(struct mapped_device *md, struct dm_table *t);
 289
 290 /*
 291  * A wrapper around vmalloc.
 292  */
 293 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 294
 295 /*-----------------------------------------------------------------
 296  * Macros.
 297  *---------------------------------------------------------------*/
 298 #define DM_NAME "device-mapper"
 299
 300 #define DMCRIT(f, arg...) \
 301         printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 302
 303 #define DMERR(f, arg...) \
 304         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 305 #define DMERR_LIMIT(f, arg...) \
 306         do { \
 307                 if (printk_ratelimit()) \
 308                         printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
 309                                f "\n", ## arg); \
 310         } while (0)
 311
 312 #define DMWARN(f, arg...) \
 313         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 314 #define DMWARN_LIMIT(f, arg...) \
 315         do { \
 316                 if (printk_ratelimit()) \
 317                         printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
 318                                f "\n", ## arg); \
 319         } while (0)
 320
 321 #define DMINFO(f, arg...) \
 322         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
 323 #define DMINFO_LIMIT(f, arg...) \
 324         do { \
 325                 if (printk_ratelimit()) \
 326                         printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
 327                                "\n", ## arg); \
 328         } while (0)
 329
 330 #ifdef CONFIG_DM_DEBUG
 331 #  define DMDEBUG(f, arg...) \
 332         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
 333 #  define DMDEBUG_LIMIT(f, arg...) \
 334         do { \
 335                 if (printk_ratelimit()) \
 336                         printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
 337                                "\n", ## arg); \
 338         } while (0)
 339 #else
 340 #  define DMDEBUG(f, arg...) do {} while (0)
 341 #  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
 342 #endif
 343
 344 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
 345                           0 : scnprintf(result + sz, maxlen - sz, x))
 346
 347 #define SECTOR_SHIFT 9
 348
 349 /*
 350  * Definitions of return values from target end_io function.
 351  */
 352 #define DM_ENDIO_INCOMPLETE     1
 353 #define DM_ENDIO_REQUEUE        2
 354
 355 /*
 356  * Definitions of return values from target map function.
 357  */
 358 #define DM_MAPIO_SUBMITTED      0
 359 #define DM_MAPIO_REMAPPED       1
 360 #define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE
 361
 362 /*
 363  * Ceiling(n / sz)
 364  */
 365 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
 366
 367 #define dm_sector_div_up(n, sz) ( \
 368 { \
 369         sector_t _r = ((n) + (sz) - 1); \
 370         sector_div(_r, (sz)); \
 371         _r; \
 372 } \
 373 )
 374
 375 /*
 376  * ceiling(n / size) * size
 377  */
 378 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
 379
 380 #define dm_array_too_big(fixed, obj, num) \
 381         ((num) > (UINT_MAX - (fixed)) / (obj))
 382
 383 static inline sector_t to_sector(unsigned long n)
 384 {
 385         return (n >> SECTOR_SHIFT);
 386 }
 387
 388 static inline unsigned long to_bytes(sector_t n)
 389 {
 390         return (n << SECTOR_SHIFT);
 391 }
 392
 393 #endif  /* _LINUX_DEVICE_MAPPER_H */