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 * Some targets need to be sent the same WRITE bio severals times so
196 * that they can send copies of it to different devices. This function
197 * examines any supplied bio and returns the number of copies of it the
198 * target requires.
199 */
200 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
201
202 struct dm_target {
203 struct dm_table *table;
204 struct target_type *type;
205
206 /* target limits */
207 sector_t begin;
208 sector_t len;
209
210 /* If non-zero, maximum size of I/O submitted to a target. */
211 uint32_t max_io_len;
212
213 /*
214 * A number of zero-length barrier bios that will be submitted
215 * to the target for the purpose of flushing cache.
216 *
217 * The bio number can be accessed with dm_bio_get_target_bio_nr.
218 * It is a responsibility of the target driver to remap these bios
219 * to the real underlying devices.
220 */
221 unsigned num_flush_bios;
222
223 /*
224 * The number of discard bios that will be submitted to the target.
225 * The bio number can be accessed with dm_bio_get_target_bio_nr.
226 */
227 unsigned num_discard_bios;
228
229 /*
230 * The number of WRITE SAME bios that will be submitted to the target.
231 * The bio number can be accessed with dm_bio_get_target_bio_nr.
232 */
233 unsigned num_write_same_bios;
234
235 /*
236 * The minimum number of extra bytes allocated in each bio for the
237 * target to use. dm_per_bio_data returns the data location.
238 */
239 unsigned per_bio_data_size;
240
241 /*
242 * If defined, this function is called to find out how many
243 * duplicate bios should be sent to the target when writing
244 * data.
245 */
246 dm_num_write_bios_fn num_write_bios;
247
248 /* target specific data */
249 void *private;
250
251 /* Used to provide an error string from the ctr */
252 char *error;
253
254 /*
255 * Set if this target needs to receive flushes regardless of
256 * whether or not its underlying devices have support.
257 */
258 bool flush_supported:1;
259
260 /*
261 * Set if this target needs to receive discards regardless of
262 * whether or not its underlying devices have support.
263 */
264 bool discards_supported:1;
265
266 /*
267 * Set if the target required discard bios to be split
268 * on max_io_len boundary.
269 */
270 bool split_discard_bios:1;
271
272 /*
273 * Set if this target does not return zeroes on discarded blocks.
274 */
275 bool discard_zeroes_data_unsupported:1;
276 };
277
278 /* Each target can link one of these into the table */
279 struct dm_target_callbacks {
280 struct list_head list;
281 int (*congested_fn) (struct dm_target_callbacks *, int);
282 };
283
284 /*
285 * For bio-based dm.
286 * One of these is allocated for each bio.
287 * This structure shouldn't be touched directly by target drivers.
288 * It is here so that we can inline dm_per_bio_data and
289 * dm_bio_from_per_bio_data
290 */
291 struct dm_target_io {
292 struct dm_io *io;
293 struct dm_target *ti;
294 unsigned target_bio_nr;
295 unsigned *len_ptr;
296 struct bio clone;
297 };
298
dm_per_bio_data(struct bio * bio,size_t data_size)299 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
300 {
301 return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
302 }
303
dm_bio_from_per_bio_data(void * data,size_t data_size)304 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
305 {
306 return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
307 }
308
dm_bio_get_target_bio_nr(const struct bio * bio)309 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
310 {
311 return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
312 }
313
314 int dm_register_target(struct target_type *t);
315 void dm_unregister_target(struct target_type *t);
316
317 /*
318 * Target argument parsing.
319 */
320 struct dm_arg_set {
321 unsigned argc;
322 char **argv;
323 };
324
325 /*
326 * The minimum and maximum value of a numeric argument, together with
327 * the error message to use if the number is found to be outside that range.
328 */
329 struct dm_arg {
330 unsigned min;
331 unsigned max;
332 char *error;
333 };
334
335 /*
336 * Validate the next argument, either returning it as *value or, if invalid,
337 * returning -EINVAL and setting *error.
338 */
339 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
340 unsigned *value, char **error);
341
342 /*
343 * Process the next argument as the start of a group containing between
344 * arg->min and arg->max further arguments. Either return the size as
345 * *num_args or, if invalid, return -EINVAL and set *error.
346 */
347 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
348 unsigned *num_args, char **error);
349
350 /*
351 * Return the current argument and shift to the next.
352 */
353 const char *dm_shift_arg(struct dm_arg_set *as);
354
355 /*
356 * Move through num_args arguments.
357 */
358 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
359
360 /*-----------------------------------------------------------------
361 * Functions for creating and manipulating mapped devices.
362 * Drop the reference with dm_put when you finish with the object.
363 *---------------------------------------------------------------*/
364
365 /*
366 * DM_ANY_MINOR chooses the next available minor number.
367 */
368 #define DM_ANY_MINOR (-1)
369 int dm_create(int minor, struct mapped_device **md);
370
371 /*
372 * Reference counting for md.
373 */
374 struct mapped_device *dm_get_md(dev_t dev);
375 void dm_get(struct mapped_device *md);
376 int dm_hold(struct mapped_device *md);
377 void dm_put(struct mapped_device *md);
378
379 /*
380 * An arbitrary pointer may be stored alongside a mapped device.
381 */
382 void dm_set_mdptr(struct mapped_device *md, void *ptr);
383 void *dm_get_mdptr(struct mapped_device *md);
384
385 /*
386 * A device can still be used while suspended, but I/O is deferred.
387 */
388 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
389 int dm_resume(struct mapped_device *md);
390
391 /*
392 * Event functions.
393 */
394 uint32_t dm_get_event_nr(struct mapped_device *md);
395 int dm_wait_event(struct mapped_device *md, int event_nr);
396 uint32_t dm_next_uevent_seq(struct mapped_device *md);
397 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
398
399 /*
400 * Info functions.
401 */
402 const char *dm_device_name(struct mapped_device *md);
403 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
404 struct gendisk *dm_disk(struct mapped_device *md);
405 int dm_suspended(struct dm_target *ti);
406 int dm_noflush_suspending(struct dm_target *ti);
407 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
408 union map_info *dm_get_rq_mapinfo(struct request *rq);
409
410 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
411
412 /*
413 * Geometry functions.
414 */
415 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
416 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
417
418 /*-----------------------------------------------------------------
419 * Functions for manipulating device-mapper tables.
420 *---------------------------------------------------------------*/
421
422 /*
423 * First create an empty table.
424 */
425 int dm_table_create(struct dm_table **result, fmode_t mode,
426 unsigned num_targets, struct mapped_device *md);
427
428 /*
429 * Then call this once for each target.
430 */
431 int dm_table_add_target(struct dm_table *t, const char *type,
432 sector_t start, sector_t len, char *params);
433
434 /*
435 * Target_ctr should call this if it needs to add any callbacks.
436 */
437 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
438
439 /*
440 * Finally call this to make the table ready for use.
441 */
442 int dm_table_complete(struct dm_table *t);
443
444 /*
445 * Target may require that it is never sent I/O larger than len.
446 */
447 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
448
449 /*
450 * Table reference counting.
451 */
452 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
453 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
454 void dm_sync_table(struct mapped_device *md);
455
456 /*
457 * Queries
458 */
459 sector_t dm_table_get_size(struct dm_table *t);
460 unsigned int dm_table_get_num_targets(struct dm_table *t);
461 fmode_t dm_table_get_mode(struct dm_table *t);
462 struct mapped_device *dm_table_get_md(struct dm_table *t);
463
464 /*
465 * Trigger an event.
466 */
467 void dm_table_event(struct dm_table *t);
468
469 /*
470 * Run the queue for request-based targets.
471 */
472 void dm_table_run_md_queue_async(struct dm_table *t);
473
474 /*
475 * The device must be suspended before calling this method.
476 * Returns the previous table, which the caller must destroy.
477 */
478 struct dm_table *dm_swap_table(struct mapped_device *md,
479 struct dm_table *t);
480
481 /*
482 * A wrapper around vmalloc.
483 */
484 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
485
486 /*-----------------------------------------------------------------
487 * Macros.
488 *---------------------------------------------------------------*/
489 #define DM_NAME "device-mapper"
490
491 #ifdef CONFIG_PRINTK
492 extern struct ratelimit_state dm_ratelimit_state;
493
494 #define dm_ratelimit() __ratelimit(&dm_ratelimit_state)
495 #else
496 #define dm_ratelimit() 0
497 #endif
498
499 #define DMCRIT(f, arg...) \
500 printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
501
502 #define DMERR(f, arg...) \
503 printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
504 #define DMERR_LIMIT(f, arg...) \
505 do { \
506 if (dm_ratelimit()) \
507 printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
508 f "\n", ## arg); \
509 } while (0)
510
511 #define DMWARN(f, arg...) \
512 printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
513 #define DMWARN_LIMIT(f, arg...) \
514 do { \
515 if (dm_ratelimit()) \
516 printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
517 f "\n", ## arg); \
518 } while (0)
519
520 #define DMINFO(f, arg...) \
521 printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
522 #define DMINFO_LIMIT(f, arg...) \
523 do { \
524 if (dm_ratelimit()) \
525 printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
526 "\n", ## arg); \
527 } while (0)
528
529 #ifdef CONFIG_DM_DEBUG
530 # define DMDEBUG(f, arg...) \
531 printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
532 # define DMDEBUG_LIMIT(f, arg...) \
533 do { \
534 if (dm_ratelimit()) \
535 printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
536 "\n", ## arg); \
537 } while (0)
538 #else
539 # define DMDEBUG(f, arg...) do {} while (0)
540 # define DMDEBUG_LIMIT(f, arg...) do {} while (0)
541 #endif
542
543 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
544 0 : scnprintf(result + sz, maxlen - sz, x))
545
546 #define SECTOR_SHIFT 9
547
548 /*
549 * Definitions of return values from target end_io function.
550 */
551 #define DM_ENDIO_INCOMPLETE 1
552 #define DM_ENDIO_REQUEUE 2
553
554 /*
555 * Definitions of return values from target map function.
556 */
557 #define DM_MAPIO_SUBMITTED 0
558 #define DM_MAPIO_REMAPPED 1
559 #define DM_MAPIO_REQUEUE DM_ENDIO_REQUEUE
560
561 #define dm_sector_div64(x, y)( \
562 { \
563 u64 _res; \
564 (x) = div64_u64_rem(x, y, &_res); \
565 _res; \
566 } \
567 )
568
569 /*
570 * Ceiling(n / sz)
571 */
572 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
573
574 #define dm_sector_div_up(n, sz) ( \
575 { \
576 sector_t _r = ((n) + (sz) - 1); \
577 sector_div(_r, (sz)); \
578 _r; \
579 } \
580 )
581
582 /*
583 * ceiling(n / size) * size
584 */
585 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
586
587 #define dm_array_too_big(fixed, obj, num) \
588 ((num) > (UINT_MAX - (fixed)) / (obj))
589
590 /*
591 * Sector offset taken relative to the start of the target instead of
592 * relative to the start of the device.
593 */
594 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
595
to_sector(unsigned long n)596 static inline sector_t to_sector(unsigned long n)
597 {
598 return (n >> SECTOR_SHIFT);
599 }
600
to_bytes(sector_t n)601 static inline unsigned long to_bytes(sector_t n)
602 {
603 return (n << SECTOR_SHIFT);
604 }
605
606 #endif /* _LINUX_DEVICE_MAPPER_H */
607