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/math64.h>
14 #include <linux/ratelimit.h>
15
16 struct dm_dev;
17 struct dm_target;
18 struct dm_table;
19 struct mapped_device;
20 struct bio_vec;
21
22 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
23
24 union map_info {
25 void *ptr;
26 };
27
28 /*
29 * In the constructor the target parameter will already have the
30 * table, type, begin and len fields filled in.
31 */
32 typedef 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 */
39 typedef 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 */
48 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio);
49 typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone,
50 union map_info *map_context);
51 typedef int (*dm_clone_and_map_request_fn) (struct dm_target *ti,
52 struct request *rq,
53 union map_info *map_context,
54 struct request **clone);
55 typedef void (*dm_release_clone_request_fn) (struct request *clone);
56
57 /*
58 * Returns:
59 * < 0 : error (currently ignored)
60 * 0 : ended successfully
61 * 1 : for some reason the io has still not completed (eg,
62 * multipath target might want to requeue a failed io).
63 * 2 : The target wants to push back the io
64 */
65 typedef int (*dm_endio_fn) (struct dm_target *ti,
66 struct bio *bio, int error);
67 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
68 struct request *clone, int error,
69 union map_info *map_context);
70
71 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
72 typedef void (*dm_presuspend_undo_fn) (struct dm_target *ti);
73 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
74 typedef int (*dm_preresume_fn) (struct dm_target *ti);
75 typedef void (*dm_resume_fn) (struct dm_target *ti);
76
77 typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
78 unsigned status_flags, char *result, unsigned maxlen);
79
80 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
81
82 typedef int (*dm_prepare_ioctl_fn) (struct dm_target *ti,
83 struct block_device **bdev, fmode_t *mode);
84
85 /*
86 * These iteration functions are typically used to check (and combine)
87 * properties of underlying devices.
88 * E.g. Does at least one underlying device support flush?
89 * Does any underlying device not support WRITE_SAME?
90 *
91 * The callout function is called once for each contiguous section of
92 * an underlying device. State can be maintained in *data.
93 * Return non-zero to stop iterating through any further devices.
94 */
95 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
96 struct dm_dev *dev,
97 sector_t start, sector_t len,
98 void *data);
99
100 /*
101 * This function must iterate through each section of device used by the
102 * target until it encounters a non-zero return code, which it then returns.
103 * Returns zero if no callout returned non-zero.
104 */
105 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
106 iterate_devices_callout_fn fn,
107 void *data);
108
109 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
110 struct queue_limits *limits);
111
112 /*
113 * Returns:
114 * 0: The target can handle the next I/O immediately.
115 * 1: The target can't handle the next I/O immediately.
116 */
117 typedef int (*dm_busy_fn) (struct dm_target *ti);
118
119 void dm_error(const char *message);
120
121 struct dm_dev {
122 struct block_device *bdev;
123 fmode_t mode;
124 char name[16];
125 };
126
127 dev_t dm_get_dev_t(const char *path);
128
129 /*
130 * Constructors should call these functions to ensure destination devices
131 * are opened/closed correctly.
132 */
133 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
134 struct dm_dev **result);
135 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
136
137 /*
138 * Information about a target type
139 */
140
141 struct target_type {
142 uint64_t features;
143 const char *name;
144 struct module *module;
145 unsigned version[3];
146 dm_ctr_fn ctr;
147 dm_dtr_fn dtr;
148 dm_map_fn map;
149 dm_map_request_fn map_rq;
150 dm_clone_and_map_request_fn clone_and_map_rq;
151 dm_release_clone_request_fn release_clone_rq;
152 dm_endio_fn end_io;
153 dm_request_endio_fn rq_end_io;
154 dm_presuspend_fn presuspend;
155 dm_presuspend_undo_fn presuspend_undo;
156 dm_postsuspend_fn postsuspend;
157 dm_preresume_fn preresume;
158 dm_resume_fn resume;
159 dm_status_fn status;
160 dm_message_fn message;
161 dm_prepare_ioctl_fn prepare_ioctl;
162 dm_busy_fn busy;
163 dm_iterate_devices_fn iterate_devices;
164 dm_io_hints_fn io_hints;
165
166 /* For internal device-mapper use. */
167 struct list_head list;
168 };
169
170 /*
171 * Target features
172 */
173
174 /*
175 * Any table that contains an instance of this target must have only one.
176 */
177 #define DM_TARGET_SINGLETON 0x00000001
178 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
179
180 /*
181 * Indicates that a target does not support read-only devices.
182 */
183 #define DM_TARGET_ALWAYS_WRITEABLE 0x00000002
184 #define dm_target_always_writeable(type) \
185 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
186
187 /*
188 * Any device that contains a table with an instance of this target may never
189 * have tables containing any different target type.
190 */
191 #define DM_TARGET_IMMUTABLE 0x00000004
192 #define dm_target_is_immutable(type) ((type)->features & DM_TARGET_IMMUTABLE)
193
194 /*
195 * Indicates that a target may replace any target; even immutable targets.
196 * .map, .map_rq, .clone_and_map_rq and .release_clone_rq are all defined.
197 */
198 #define DM_TARGET_WILDCARD 0x00000008
199 #define dm_target_is_wildcard(type) ((type)->features & DM_TARGET_WILDCARD)
200
201 /*
202 * Some targets need to be sent the same WRITE bio severals times so
203 * that they can send copies of it to different devices. This function
204 * examines any supplied bio and returns the number of copies of it the
205 * target requires.
206 */
207 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
208
209 struct dm_target {
210 struct dm_table *table;
211 struct target_type *type;
212
213 /* target limits */
214 sector_t begin;
215 sector_t len;
216
217 /* If non-zero, maximum size of I/O submitted to a target. */
218 uint32_t max_io_len;
219
220 /*
221 * A number of zero-length barrier bios that will be submitted
222 * to the target for the purpose of flushing cache.
223 *
224 * The bio number can be accessed with dm_bio_get_target_bio_nr.
225 * It is a responsibility of the target driver to remap these bios
226 * to the real underlying devices.
227 */
228 unsigned num_flush_bios;
229
230 /*
231 * The number of discard bios that will be submitted to the target.
232 * The bio number can be accessed with dm_bio_get_target_bio_nr.
233 */
234 unsigned num_discard_bios;
235
236 /*
237 * The number of WRITE SAME bios that will be submitted to the target.
238 * The bio number can be accessed with dm_bio_get_target_bio_nr.
239 */
240 unsigned num_write_same_bios;
241
242 /*
243 * The minimum number of extra bytes allocated in each io for the
244 * target to use.
245 */
246 unsigned per_io_data_size;
247
248 /*
249 * If defined, this function is called to find out how many
250 * duplicate bios should be sent to the target when writing
251 * data.
252 */
253 dm_num_write_bios_fn num_write_bios;
254
255 /* target specific data */
256 void *private;
257
258 /* Used to provide an error string from the ctr */
259 char *error;
260
261 /*
262 * Set if this target needs to receive flushes regardless of
263 * whether or not its underlying devices have support.
264 */
265 bool flush_supported:1;
266
267 /*
268 * Set if this target needs to receive discards regardless of
269 * whether or not its underlying devices have support.
270 */
271 bool discards_supported:1;
272
273 /*
274 * Set if the target required discard bios to be split
275 * on max_io_len boundary.
276 */
277 bool split_discard_bios:1;
278
279 /*
280 * Set if this target does not return zeroes on discarded blocks.
281 */
282 bool discard_zeroes_data_unsupported:1;
283 };
284
285 /* Each target can link one of these into the table */
286 struct dm_target_callbacks {
287 struct list_head list;
288 int (*congested_fn) (struct dm_target_callbacks *, int);
289 };
290
291 /*
292 * For bio-based dm.
293 * One of these is allocated for each bio.
294 * This structure shouldn't be touched directly by target drivers.
295 * It is here so that we can inline dm_per_bio_data and
296 * dm_bio_from_per_bio_data
297 */
298 struct dm_target_io {
299 struct dm_io *io;
300 struct dm_target *ti;
301 unsigned target_bio_nr;
302 unsigned *len_ptr;
303 struct bio clone;
304 };
305
306 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
307 {
308 return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
309 }
310
311 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
312 {
313 return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
314 }
315
316 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
317 {
318 return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
319 }
320
321 int dm_register_target(struct target_type *t);
322 void dm_unregister_target(struct target_type *t);
323
324 /*
325 * Target argument parsing.
326 */
327 struct dm_arg_set {
328 unsigned argc;
329 char **argv;
330 };
331
332 /*
333 * The minimum and maximum value of a numeric argument, together with
334 * the error message to use if the number is found to be outside that range.
335 */
336 struct dm_arg {
337 unsigned min;
338 unsigned max;
339 char *error;
340 };
341
342 /*
343 * Validate the next argument, either returning it as *value or, if invalid,
344 * returning -EINVAL and setting *error.
345 */
346 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
347 unsigned *value, char **error);
348
349 /*
350 * Process the next argument as the start of a group containing between
351 * arg->min and arg->max further arguments. Either return the size as
352 * *num_args or, if invalid, return -EINVAL and set *error.
353 */
354 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
355 unsigned *num_args, char **error);
356
357 /*
358 * Return the current argument and shift to the next.
359 */
360 const char *dm_shift_arg(struct dm_arg_set *as);
361
362 /*
363 * Move through num_args arguments.
364 */
365 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
366
367 /*-----------------------------------------------------------------
368 * Functions for creating and manipulating mapped devices.
369 * Drop the reference with dm_put when you finish with the object.
370 *---------------------------------------------------------------*/
371
372 /*
373 * DM_ANY_MINOR chooses the next available minor number.
374 */
375 #define DM_ANY_MINOR (-1)
376 int dm_create(int minor, struct mapped_device **md);
377
378 /*
379 * Reference counting for md.
380 */
381 struct mapped_device *dm_get_md(dev_t dev);
382 void dm_get(struct mapped_device *md);
383 int dm_hold(struct mapped_device *md);
384 void dm_put(struct mapped_device *md);
385
386 /*
387 * An arbitrary pointer may be stored alongside a mapped device.
388 */
389 void dm_set_mdptr(struct mapped_device *md, void *ptr);
390 void *dm_get_mdptr(struct mapped_device *md);
391
392 /*
393 * A device can still be used while suspended, but I/O is deferred.
394 */
395 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
396 int dm_resume(struct mapped_device *md);
397
398 /*
399 * Event functions.
400 */
401 uint32_t dm_get_event_nr(struct mapped_device *md);
402 int dm_wait_event(struct mapped_device *md, int event_nr);
403 uint32_t dm_next_uevent_seq(struct mapped_device *md);
404 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
405
406 /*
407 * Info functions.
408 */
409 const char *dm_device_name(struct mapped_device *md);
410 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
411 struct gendisk *dm_disk(struct mapped_device *md);
412 int dm_suspended(struct dm_target *ti);
413 int dm_noflush_suspending(struct dm_target *ti);
414 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
415 union map_info *dm_get_rq_mapinfo(struct request *rq);
416
417 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
418
419 /*
420 * Geometry functions.
421 */
422 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
423 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
424
425 /*-----------------------------------------------------------------
426 * Functions for manipulating device-mapper tables.
427 *---------------------------------------------------------------*/
428
429 /*
430 * First create an empty table.
431 */
432 int dm_table_create(struct dm_table **result, fmode_t mode,
433 unsigned num_targets, struct mapped_device *md);
434
435 /*
436 * Then call this once for each target.
437 */
438 int dm_table_add_target(struct dm_table *t, const char *type,
439 sector_t start, sector_t len, char *params);
440
441 /*
442 * Target_ctr should call this if it needs to add any callbacks.
443 */
444 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
445
446 /*
447 * Finally call this to make the table ready for use.
448 */
449 int dm_table_complete(struct dm_table *t);
450
451 /*
452 * Target may require that it is never sent I/O larger than len.
453 */
454 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
455
456 /*
457 * Table reference counting.
458 */
459 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
460 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
461 void dm_sync_table(struct mapped_device *md);
462
463 /*
464 * Queries
465 */
466 sector_t dm_table_get_size(struct dm_table *t);
467 unsigned int dm_table_get_num_targets(struct dm_table *t);
468 fmode_t dm_table_get_mode(struct dm_table *t);
469 struct mapped_device *dm_table_get_md(struct dm_table *t);
470
471 /*
472 * Trigger an event.
473 */
474 void dm_table_event(struct dm_table *t);
475
476 /*
477 * Run the queue for request-based targets.
478 */
479 void dm_table_run_md_queue_async(struct dm_table *t);
480
481 /*
482 * The device must be suspended before calling this method.
483 * Returns the previous table, which the caller must destroy.
484 */
485 struct dm_table *dm_swap_table(struct mapped_device *md,
486 struct dm_table *t);
487
488 /*
489 * A wrapper around vmalloc.
490 */
491 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
492
493 /*-----------------------------------------------------------------
494 * Macros.
495 *---------------------------------------------------------------*/
496 #define DM_NAME "device-mapper"
497
498 #ifdef CONFIG_PRINTK
499 extern struct ratelimit_state dm_ratelimit_state;
500
501 #define dm_ratelimit() __ratelimit(&dm_ratelimit_state)
502 #else
503 #define dm_ratelimit() 0
504 #endif
505
506 #define DMCRIT(f, arg...) \
507 printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
508
509 #define DMERR(f, arg...) \
510 printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
511 #define DMERR_LIMIT(f, arg...) \
512 do { \
513 if (dm_ratelimit()) \
514 printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
515 f "\n", ## arg); \
516 } while (0)
517
518 #define DMWARN(f, arg...) \
519 printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
520 #define DMWARN_LIMIT(f, arg...) \
521 do { \
522 if (dm_ratelimit()) \
523 printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
524 f "\n", ## arg); \
525 } while (0)
526
527 #define DMINFO(f, arg...) \
528 printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
529 #define DMINFO_LIMIT(f, arg...) \
530 do { \
531 if (dm_ratelimit()) \
532 printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
533 "\n", ## arg); \
534 } while (0)
535
536 #ifdef CONFIG_DM_DEBUG
537 # define DMDEBUG(f, arg...) \
538 printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
539 # define DMDEBUG_LIMIT(f, arg...) \
540 do { \
541 if (dm_ratelimit()) \
542 printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
543 "\n", ## arg); \
544 } while (0)
545 #else
546 # define DMDEBUG(f, arg...) do {} while (0)
547 # define DMDEBUG_LIMIT(f, arg...) do {} while (0)
548 #endif
549
550 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
551 0 : scnprintf(result + sz, maxlen - sz, x))
552
553 #define SECTOR_SHIFT 9
554
555 /*
556 * Definitions of return values from target end_io function.
557 */
558 #define DM_ENDIO_INCOMPLETE 1
559 #define DM_ENDIO_REQUEUE 2
560
561 /*
562 * Definitions of return values from target map function.
563 */
564 #define DM_MAPIO_SUBMITTED 0
565 #define DM_MAPIO_REMAPPED 1
566 #define DM_MAPIO_REQUEUE DM_ENDIO_REQUEUE
567
568 #define dm_sector_div64(x, y)( \
569 { \
570 u64 _res; \
571 (x) = div64_u64_rem(x, y, &_res); \
572 _res; \
573 } \
574 )
575
576 /*
577 * Ceiling(n / sz)
578 */
579 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
580
581 #define dm_sector_div_up(n, sz) ( \
582 { \
583 sector_t _r = ((n) + (sz) - 1); \
584 sector_div(_r, (sz)); \
585 _r; \
586 } \
587 )
588
589 /*
590 * ceiling(n / size) * size
591 */
592 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
593
594 #define dm_array_too_big(fixed, obj, num) \
595 ((num) > (UINT_MAX - (fixed)) / (obj))
596
597 /*
598 * Sector offset taken relative to the start of the target instead of
599 * relative to the start of the device.
600 */
601 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
602
603 static inline sector_t to_sector(unsigned long n)
604 {
605 return (n >> SECTOR_SHIFT);
606 }
607
608 static inline unsigned long to_bytes(sector_t n)
609 {
610 return (n << SECTOR_SHIFT);
611 }
612
613 #endif /* _LINUX_DEVICE_MAPPER_H */
614
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