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 /*
23 * Type of table, mapped_device's mempool and request_queue
24 */
25 #define DM_TYPE_NONE 0
26 #define DM_TYPE_BIO_BASED 1
27 #define DM_TYPE_REQUEST_BASED 2
28 #define DM_TYPE_MQ_REQUEST_BASED 3
29 #define DM_TYPE_DAX_BIO_BASED 4
30
31 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
32
33 union map_info {
34 void *ptr;
35 };
36
37 /*
38 * In the constructor the target parameter will already have the
39 * table, type, begin and len fields filled in.
40 */
41 typedef int (*dm_ctr_fn) (struct dm_target *target,
42 unsigned int argc, char **argv);
43
44 /*
45 * The destructor doesn't need to free the dm_target, just
46 * anything hidden ti->private.
47 */
48 typedef void (*dm_dtr_fn) (struct dm_target *ti);
49
50 /*
51 * The map function must return:
52 * < 0: error
53 * = 0: The target will handle the io by resubmitting it later
54 * = 1: simple remap complete
55 * = 2: The target wants to push back the io
56 */
57 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio);
58 typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone,
59 union map_info *map_context);
60 typedef int (*dm_clone_and_map_request_fn) (struct dm_target *ti,
61 struct request *rq,
62 union map_info *map_context,
63 struct request **clone);
64 typedef void (*dm_release_clone_request_fn) (struct request *clone);
65
66 /*
67 * Returns:
68 * < 0 : error (currently ignored)
69 * 0 : ended successfully
70 * 1 : for some reason the io has still not completed (eg,
71 * multipath target might want to requeue a failed io).
72 * 2 : The target wants to push back the io
73 */
74 typedef int (*dm_endio_fn) (struct dm_target *ti,
75 struct bio *bio, int error);
76 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
77 struct request *clone, int error,
78 union map_info *map_context);
79
80 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
81 typedef void (*dm_presuspend_undo_fn) (struct dm_target *ti);
82 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
83 typedef int (*dm_preresume_fn) (struct dm_target *ti);
84 typedef void (*dm_resume_fn) (struct dm_target *ti);
85
86 typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
87 unsigned status_flags, char *result, unsigned maxlen);
88
89 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
90
91 typedef int (*dm_prepare_ioctl_fn) (struct dm_target *ti,
92 struct block_device **bdev, fmode_t *mode);
93
94 /*
95 * These iteration functions are typically used to check (and combine)
96 * properties of underlying devices.
97 * E.g. Does at least one underlying device support flush?
98 * Does any underlying device not support WRITE_SAME?
99 *
100 * The callout function is called once for each contiguous section of
101 * an underlying device. State can be maintained in *data.
102 * Return non-zero to stop iterating through any further devices.
103 */
104 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
105 struct dm_dev *dev,
106 sector_t start, sector_t len,
107 void *data);
108
109 /*
110 * This function must iterate through each section of device used by the
111 * target until it encounters a non-zero return code, which it then returns.
112 * Returns zero if no callout returned non-zero.
113 */
114 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
115 iterate_devices_callout_fn fn,
116 void *data);
117
118 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
119 struct queue_limits *limits);
120
121 /*
122 * Returns:
123 * 0: The target can handle the next I/O immediately.
124 * 1: The target can't handle the next I/O immediately.
125 */
126 typedef int (*dm_busy_fn) (struct dm_target *ti);
127
128 /*
129 * Returns:
130 * < 0 : error
131 * >= 0 : the number of bytes accessible at the address
132 */
133 typedef long (*dm_direct_access_fn) (struct dm_target *ti, sector_t sector,
134 void **kaddr, pfn_t *pfn, long size);
135
136 void dm_error(const char *message);
137
138 struct dm_dev {
139 struct block_device *bdev;
140 fmode_t mode;
141 char name[16];
142 };
143
144 dev_t dm_get_dev_t(const char *path);
145
146 /*
147 * Constructors should call these functions to ensure destination devices
148 * are opened/closed correctly.
149 */
150 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
151 struct dm_dev **result);
152 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
153
154 /*
155 * Information about a target type
156 */
157
158 struct target_type {
159 uint64_t features;
160 const char *name;
161 struct module *module;
162 unsigned version[3];
163 dm_ctr_fn ctr;
164 dm_dtr_fn dtr;
165 dm_map_fn map;
166 dm_map_request_fn map_rq;
167 dm_clone_and_map_request_fn clone_and_map_rq;
168 dm_release_clone_request_fn release_clone_rq;
169 dm_endio_fn end_io;
170 dm_request_endio_fn rq_end_io;
171 dm_presuspend_fn presuspend;
172 dm_presuspend_undo_fn presuspend_undo;
173 dm_postsuspend_fn postsuspend;
174 dm_preresume_fn preresume;
175 dm_resume_fn resume;
176 dm_status_fn status;
177 dm_message_fn message;
178 dm_prepare_ioctl_fn prepare_ioctl;
179 dm_busy_fn busy;
180 dm_iterate_devices_fn iterate_devices;
181 dm_io_hints_fn io_hints;
182 dm_direct_access_fn direct_access;
183
184 /* For internal device-mapper use. */
185 struct list_head list;
186 };
187
188 /*
189 * Target features
190 */
191
192 /*
193 * Any table that contains an instance of this target must have only one.
194 */
195 #define DM_TARGET_SINGLETON 0x00000001
196 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
197
198 /*
199 * Indicates that a target does not support read-only devices.
200 */
201 #define DM_TARGET_ALWAYS_WRITEABLE 0x00000002
202 #define dm_target_always_writeable(type) \
203 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
204
205 /*
206 * Any device that contains a table with an instance of this target may never
207 * have tables containing any different target type.
208 */
209 #define DM_TARGET_IMMUTABLE 0x00000004
210 #define dm_target_is_immutable(type) ((type)->features & DM_TARGET_IMMUTABLE)
211
212 /*
213 * Indicates that a target may replace any target; even immutable targets.
214 * .map, .map_rq, .clone_and_map_rq and .release_clone_rq are all defined.
215 */
216 #define DM_TARGET_WILDCARD 0x00000008
217 #define dm_target_is_wildcard(type) ((type)->features & DM_TARGET_WILDCARD)
218
219 /*
220 * Some targets need to be sent the same WRITE bio severals times so
221 * that they can send copies of it to different devices. This function
222 * examines any supplied bio and returns the number of copies of it the
223 * target requires.
224 */
225 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
226
227 struct dm_target {
228 struct dm_table *table;
229 struct target_type *type;
230
231 /* target limits */
232 sector_t begin;
233 sector_t len;
234
235 /* If non-zero, maximum size of I/O submitted to a target. */
236 uint32_t max_io_len;
237
238 /*
239 * A number of zero-length barrier bios that will be submitted
240 * to the target for the purpose of flushing cache.
241 *
242 * The bio number can be accessed with dm_bio_get_target_bio_nr.
243 * It is a responsibility of the target driver to remap these bios
244 * to the real underlying devices.
245 */
246 unsigned num_flush_bios;
247
248 /*
249 * The number of discard bios that will be submitted to the target.
250 * The bio number can be accessed with dm_bio_get_target_bio_nr.
251 */
252 unsigned num_discard_bios;
253
254 /*
255 * The number of WRITE SAME bios that will be submitted to the target.
256 * The bio number can be accessed with dm_bio_get_target_bio_nr.
257 */
258 unsigned num_write_same_bios;
259
260 /*
261 * The minimum number of extra bytes allocated in each io for the
262 * target to use.
263 */
264 unsigned per_io_data_size;
265
266 /*
267 * If defined, this function is called to find out how many
268 * duplicate bios should be sent to the target when writing
269 * data.
270 */
271 dm_num_write_bios_fn num_write_bios;
272
273 /* target specific data */
274 void *private;
275
276 /* Used to provide an error string from the ctr */
277 char *error;
278
279 /*
280 * Set if this target needs to receive flushes regardless of
281 * whether or not its underlying devices have support.
282 */
283 bool flush_supported:1;
284
285 /*
286 * Set if this target needs to receive discards regardless of
287 * whether or not its underlying devices have support.
288 */
289 bool discards_supported:1;
290
291 /*
292 * Set if the target required discard bios to be split
293 * on max_io_len boundary.
294 */
295 bool split_discard_bios:1;
296
297 /*
298 * Set if this target does not return zeroes on discarded blocks.
299 */
300 bool discard_zeroes_data_unsupported:1;
301 };
302
303 /* Each target can link one of these into the table */
304 struct dm_target_callbacks {
305 struct list_head list;
306 int (*congested_fn) (struct dm_target_callbacks *, int);
307 };
308
309 /*
310 * For bio-based dm.
311 * One of these is allocated for each bio.
312 * This structure shouldn't be touched directly by target drivers.
313 * It is here so that we can inline dm_per_bio_data and
314 * dm_bio_from_per_bio_data
315 */
316 struct dm_target_io {
317 struct dm_io *io;
318 struct dm_target *ti;
319 unsigned target_bio_nr;
320 unsigned *len_ptr;
321 struct bio clone;
322 };
323
dm_per_bio_data(struct bio * bio,size_t data_size)324 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
325 {
326 return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
327 }
328
dm_bio_from_per_bio_data(void * data,size_t data_size)329 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
330 {
331 return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
332 }
333
dm_bio_get_target_bio_nr(const struct bio * bio)334 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
335 {
336 return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
337 }
338
339 int dm_register_target(struct target_type *t);
340 void dm_unregister_target(struct target_type *t);
341
342 /*
343 * Target argument parsing.
344 */
345 struct dm_arg_set {
346 unsigned argc;
347 char **argv;
348 };
349
350 /*
351 * The minimum and maximum value of a numeric argument, together with
352 * the error message to use if the number is found to be outside that range.
353 */
354 struct dm_arg {
355 unsigned min;
356 unsigned max;
357 char *error;
358 };
359
360 /*
361 * Validate the next argument, either returning it as *value or, if invalid,
362 * returning -EINVAL and setting *error.
363 */
364 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
365 unsigned *value, char **error);
366
367 /*
368 * Process the next argument as the start of a group containing between
369 * arg->min and arg->max further arguments. Either return the size as
370 * *num_args or, if invalid, return -EINVAL and set *error.
371 */
372 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
373 unsigned *num_args, char **error);
374
375 /*
376 * Return the current argument and shift to the next.
377 */
378 const char *dm_shift_arg(struct dm_arg_set *as);
379
380 /*
381 * Move through num_args arguments.
382 */
383 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
384
385 /*-----------------------------------------------------------------
386 * Functions for creating and manipulating mapped devices.
387 * Drop the reference with dm_put when you finish with the object.
388 *---------------------------------------------------------------*/
389
390 /*
391 * DM_ANY_MINOR chooses the next available minor number.
392 */
393 #define DM_ANY_MINOR (-1)
394 int dm_create(int minor, struct mapped_device **md);
395
396 /*
397 * Reference counting for md.
398 */
399 struct mapped_device *dm_get_md(dev_t dev);
400 void dm_get(struct mapped_device *md);
401 int dm_hold(struct mapped_device *md);
402 void dm_put(struct mapped_device *md);
403
404 /*
405 * An arbitrary pointer may be stored alongside a mapped device.
406 */
407 void dm_set_mdptr(struct mapped_device *md, void *ptr);
408 void *dm_get_mdptr(struct mapped_device *md);
409
410 /*
411 * Export the device via the ioctl interface (uses mdptr).
412 */
413 int dm_ioctl_export(struct mapped_device *md, const char *name,
414 const char *uuid);
415
416 /*
417 * A device can still be used while suspended, but I/O is deferred.
418 */
419 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
420 int dm_resume(struct mapped_device *md);
421
422 /*
423 * Event functions.
424 */
425 uint32_t dm_get_event_nr(struct mapped_device *md);
426 int dm_wait_event(struct mapped_device *md, int event_nr);
427 uint32_t dm_next_uevent_seq(struct mapped_device *md);
428 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
429
430 /*
431 * Info functions.
432 */
433 const char *dm_device_name(struct mapped_device *md);
434 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
435 struct gendisk *dm_disk(struct mapped_device *md);
436 int dm_suspended(struct dm_target *ti);
437 int dm_noflush_suspending(struct dm_target *ti);
438 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
439 union map_info *dm_get_rq_mapinfo(struct request *rq);
440
441 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
442
443 void dm_lock_md_type(struct mapped_device *md);
444 void dm_unlock_md_type(struct mapped_device *md);
445 void dm_set_md_type(struct mapped_device *md, unsigned type);
446 unsigned dm_get_md_type(struct mapped_device *md);
447 int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t);
448 unsigned dm_table_get_type(struct dm_table *t);
449
450 /*
451 * Geometry functions.
452 */
453 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
454 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
455
456 /*-----------------------------------------------------------------
457 * Functions for manipulating device-mapper tables.
458 *---------------------------------------------------------------*/
459
460 /*
461 * First create an empty table.
462 */
463 int dm_table_create(struct dm_table **result, fmode_t mode,
464 unsigned num_targets, struct mapped_device *md);
465
466 /*
467 * Then call this once for each target.
468 */
469 int dm_table_add_target(struct dm_table *t, const char *type,
470 sector_t start, sector_t len, char *params);
471
472 /*
473 * Target_ctr should call this if it needs to add any callbacks.
474 */
475 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
476
477 /*
478 * Target can use this to set the table's type.
479 * Can only ever be called from a target's ctr.
480 * Useful for "hybrid" target (supports both bio-based
481 * and request-based).
482 */
483 void dm_table_set_type(struct dm_table *t, unsigned type);
484
485 /*
486 * Finally call this to make the table ready for use.
487 */
488 int dm_table_complete(struct dm_table *t);
489
490 /*
491 * Target may require that it is never sent I/O larger than len.
492 */
493 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
494
495 /*
496 * Table reference counting.
497 */
498 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
499 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
500 void dm_sync_table(struct mapped_device *md);
501
502 /*
503 * Queries
504 */
505 sector_t dm_table_get_size(struct dm_table *t);
506 unsigned int dm_table_get_num_targets(struct dm_table *t);
507 fmode_t dm_table_get_mode(struct dm_table *t);
508 struct mapped_device *dm_table_get_md(struct dm_table *t);
509
510 /*
511 * Trigger an event.
512 */
513 void dm_table_event(struct dm_table *t);
514
515 /*
516 * Run the queue for request-based targets.
517 */
518 void dm_table_run_md_queue_async(struct dm_table *t);
519
520 /*
521 * The device must be suspended before calling this method.
522 * Returns the previous table, which the caller must destroy.
523 */
524 struct dm_table *dm_swap_table(struct mapped_device *md,
525 struct dm_table *t);
526
527 /*
528 * A wrapper around vmalloc.
529 */
530 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
531
532 /*-----------------------------------------------------------------
533 * Macros.
534 *---------------------------------------------------------------*/
535 #define DM_NAME "device-mapper"
536
537 #ifdef CONFIG_PRINTK
538 extern struct ratelimit_state dm_ratelimit_state;
539
540 #define dm_ratelimit() __ratelimit(&dm_ratelimit_state)
541 #else
542 #define dm_ratelimit() 0
543 #endif
544
545 #define DMCRIT(f, arg...) \
546 printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
547
548 #define DMERR(f, arg...) \
549 printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
550 #define DMERR_LIMIT(f, arg...) \
551 do { \
552 if (dm_ratelimit()) \
553 printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
554 f "\n", ## arg); \
555 } while (0)
556
557 #define DMWARN(f, arg...) \
558 printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
559 #define DMWARN_LIMIT(f, arg...) \
560 do { \
561 if (dm_ratelimit()) \
562 printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
563 f "\n", ## arg); \
564 } while (0)
565
566 #define DMINFO(f, arg...) \
567 printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
568 #define DMINFO_LIMIT(f, arg...) \
569 do { \
570 if (dm_ratelimit()) \
571 printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
572 "\n", ## arg); \
573 } while (0)
574
575 #ifdef CONFIG_DM_DEBUG
576 # define DMDEBUG(f, arg...) \
577 printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
578 # define DMDEBUG_LIMIT(f, arg...) \
579 do { \
580 if (dm_ratelimit()) \
581 printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
582 "\n", ## arg); \
583 } while (0)
584 #else
585 # define DMDEBUG(f, arg...) do {} while (0)
586 # define DMDEBUG_LIMIT(f, arg...) do {} while (0)
587 #endif
588
589 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
590 0 : scnprintf(result + sz, maxlen - sz, x))
591
592 #define SECTOR_SHIFT 9
593
594 /*
595 * Definitions of return values from target end_io function.
596 */
597 #define DM_ENDIO_INCOMPLETE 1
598 #define DM_ENDIO_REQUEUE 2
599
600 /*
601 * Definitions of return values from target map function.
602 */
603 #define DM_MAPIO_SUBMITTED 0
604 #define DM_MAPIO_REMAPPED 1
605 #define DM_MAPIO_REQUEUE DM_ENDIO_REQUEUE
606 #define DM_MAPIO_DELAY_REQUEUE 3
607
608 #define dm_sector_div64(x, y)( \
609 { \
610 u64 _res; \
611 (x) = div64_u64_rem(x, y, &_res); \
612 _res; \
613 } \
614 )
615
616 /*
617 * Ceiling(n / sz)
618 */
619 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
620
621 #define dm_sector_div_up(n, sz) ( \
622 { \
623 sector_t _r = ((n) + (sz) - 1); \
624 sector_div(_r, (sz)); \
625 _r; \
626 } \
627 )
628
629 /*
630 * ceiling(n / size) * size
631 */
632 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
633
634 #define dm_array_too_big(fixed, obj, num) \
635 ((num) > (UINT_MAX - (fixed)) / (obj))
636
637 /*
638 * Sector offset taken relative to the start of the target instead of
639 * relative to the start of the device.
640 */
641 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
642
to_sector(unsigned long n)643 static inline sector_t to_sector(unsigned long n)
644 {
645 return (n >> SECTOR_SHIFT);
646 }
647
to_bytes(sector_t n)648 static inline unsigned long to_bytes(sector_t n)
649 {
650 return (n << SECTOR_SHIFT);
651 }
652
653 #endif /* _LINUX_DEVICE_MAPPER_H */
654