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 enum dm_queue_mode {
26 DM_TYPE_NONE = 0,
27 DM_TYPE_BIO_BASED = 1,
28 DM_TYPE_REQUEST_BASED = 2,
29 DM_TYPE_MQ_REQUEST_BASED = 3,
30 DM_TYPE_DAX_BIO_BASED = 4,
31 };
32
33 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
34
35 union map_info {
36 void *ptr;
37 };
38
39 /*
40 * In the constructor the target parameter will already have the
41 * table, type, begin and len fields filled in.
42 */
43 typedef int (*dm_ctr_fn) (struct dm_target *target,
44 unsigned int argc, char **argv);
45
46 /*
47 * The destructor doesn't need to free the dm_target, just
48 * anything hidden ti->private.
49 */
50 typedef void (*dm_dtr_fn) (struct dm_target *ti);
51
52 /*
53 * The map function must return:
54 * < 0: error
55 * = 0: The target will handle the io by resubmitting it later
56 * = 1: simple remap complete
57 * = 2: The target wants to push back the io
58 */
59 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio);
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, blk_status_t *error);
76 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
77 struct request *clone, blk_status_t 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_dax_direct_access_fn) (struct dm_target *ti, pgoff_t pgoff,
134 long nr_pages, void **kaddr, pfn_t *pfn);
135 typedef size_t (*dm_dax_copy_from_iter_fn)(struct dm_target *ti, pgoff_t pgoff,
136 void *addr, size_t bytes, struct iov_iter *i);
137 #define PAGE_SECTORS (PAGE_SIZE / 512)
138
139 void dm_error(const char *message);
140
141 struct dm_dev {
142 struct block_device *bdev;
143 struct dax_device *dax_dev;
144 fmode_t mode;
145 char name[16];
146 };
147
148 dev_t dm_get_dev_t(const char *path);
149
150 /*
151 * Constructors should call these functions to ensure destination devices
152 * are opened/closed correctly.
153 */
154 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
155 struct dm_dev **result);
156 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
157
158 /*
159 * Information about a target type
160 */
161
162 struct target_type {
163 uint64_t features;
164 const char *name;
165 struct module *module;
166 unsigned version[3];
167 dm_ctr_fn ctr;
168 dm_dtr_fn dtr;
169 dm_map_fn map;
170 dm_clone_and_map_request_fn clone_and_map_rq;
171 dm_release_clone_request_fn release_clone_rq;
172 dm_endio_fn end_io;
173 dm_request_endio_fn rq_end_io;
174 dm_presuspend_fn presuspend;
175 dm_presuspend_undo_fn presuspend_undo;
176 dm_postsuspend_fn postsuspend;
177 dm_preresume_fn preresume;
178 dm_resume_fn resume;
179 dm_status_fn status;
180 dm_message_fn message;
181 dm_prepare_ioctl_fn prepare_ioctl;
182 dm_busy_fn busy;
183 dm_iterate_devices_fn iterate_devices;
184 dm_io_hints_fn io_hints;
185 dm_dax_direct_access_fn direct_access;
186 dm_dax_copy_from_iter_fn dax_copy_from_iter;
187
188 /* For internal device-mapper use. */
189 struct list_head list;
190 };
191
192 /*
193 * Target features
194 */
195
196 /*
197 * Any table that contains an instance of this target must have only one.
198 */
199 #define DM_TARGET_SINGLETON 0x00000001
200 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
201
202 /*
203 * Indicates that a target does not support read-only devices.
204 */
205 #define DM_TARGET_ALWAYS_WRITEABLE 0x00000002
206 #define dm_target_always_writeable(type) \
207 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
208
209 /*
210 * Any device that contains a table with an instance of this target may never
211 * have tables containing any different target type.
212 */
213 #define DM_TARGET_IMMUTABLE 0x00000004
214 #define dm_target_is_immutable(type) ((type)->features & DM_TARGET_IMMUTABLE)
215
216 /*
217 * Indicates that a target may replace any target; even immutable targets.
218 * .map, .map_rq, .clone_and_map_rq and .release_clone_rq are all defined.
219 */
220 #define DM_TARGET_WILDCARD 0x00000008
221 #define dm_target_is_wildcard(type) ((type)->features & DM_TARGET_WILDCARD)
222
223 /*
224 * Some targets need to be sent the same WRITE bio severals times so
225 * that they can send copies of it to different devices. This function
226 * examines any supplied bio and returns the number of copies of it the
227 * target requires.
228 */
229 typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
230
231 /*
232 * A target implements own bio data integrity.
233 */
234 #define DM_TARGET_INTEGRITY 0x00000010
235 #define dm_target_has_integrity(type) ((type)->features & DM_TARGET_INTEGRITY)
236
237 /*
238 * A target passes integrity data to the lower device.
239 */
240 #define DM_TARGET_PASSES_INTEGRITY 0x00000020
241 #define dm_target_passes_integrity(type) ((type)->features & DM_TARGET_PASSES_INTEGRITY)
242
243 /*
244 * Indicates that a target supports host-managed zoned block devices.
245 */
246 #define DM_TARGET_ZONED_HM 0x00000040
247 #define dm_target_supports_zoned_hm(type) ((type)->features & DM_TARGET_ZONED_HM)
248
249 struct dm_target {
250 struct dm_table *table;
251 struct target_type *type;
252
253 /* target limits */
254 sector_t begin;
255 sector_t len;
256
257 /* If non-zero, maximum size of I/O submitted to a target. */
258 uint32_t max_io_len;
259
260 /*
261 * A number of zero-length barrier bios that will be submitted
262 * to the target for the purpose of flushing cache.
263 *
264 * The bio number can be accessed with dm_bio_get_target_bio_nr.
265 * It is a responsibility of the target driver to remap these bios
266 * to the real underlying devices.
267 */
268 unsigned num_flush_bios;
269
270 /*
271 * The number of discard bios that will be submitted to the target.
272 * The bio number can be accessed with dm_bio_get_target_bio_nr.
273 */
274 unsigned num_discard_bios;
275
276 /*
277 * The number of WRITE SAME bios that will be submitted to the target.
278 * The bio number can be accessed with dm_bio_get_target_bio_nr.
279 */
280 unsigned num_write_same_bios;
281
282 /*
283 * The number of WRITE ZEROES bios that will be submitted to the target.
284 * The bio number can be accessed with dm_bio_get_target_bio_nr.
285 */
286 unsigned num_write_zeroes_bios;
287
288 /*
289 * The minimum number of extra bytes allocated in each io for the
290 * target to use.
291 */
292 unsigned per_io_data_size;
293
294 /*
295 * If defined, this function is called to find out how many
296 * duplicate bios should be sent to the target when writing
297 * data.
298 */
299 dm_num_write_bios_fn num_write_bios;
300
301 /* target specific data */
302 void *private;
303
304 /* Used to provide an error string from the ctr */
305 char *error;
306
307 /*
308 * Set if this target needs to receive flushes regardless of
309 * whether or not its underlying devices have support.
310 */
311 bool flush_supported:1;
312
313 /*
314 * Set if this target needs to receive discards regardless of
315 * whether or not its underlying devices have support.
316 */
317 bool discards_supported:1;
318
319 /*
320 * Set if the target required discard bios to be split
321 * on max_io_len boundary.
322 */
323 bool split_discard_bios:1;
324 };
325
326 /* Each target can link one of these into the table */
327 struct dm_target_callbacks {
328 struct list_head list;
329 int (*congested_fn) (struct dm_target_callbacks *, int);
330 };
331
332 /*
333 * For bio-based dm.
334 * One of these is allocated for each bio.
335 * This structure shouldn't be touched directly by target drivers.
336 * It is here so that we can inline dm_per_bio_data and
337 * dm_bio_from_per_bio_data
338 */
339 struct dm_target_io {
340 struct dm_io *io;
341 struct dm_target *ti;
342 unsigned target_bio_nr;
343 unsigned *len_ptr;
344 struct bio clone;
345 };
346
dm_per_bio_data(struct bio * bio,size_t data_size)347 static inline void *dm_per_bio_data(struct bio *bio, size_t data_size)
348 {
349 return (char *)bio - offsetof(struct dm_target_io, clone) - data_size;
350 }
351
dm_bio_from_per_bio_data(void * data,size_t data_size)352 static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
353 {
354 return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone));
355 }
356
dm_bio_get_target_bio_nr(const struct bio * bio)357 static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio)
358 {
359 return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
360 }
361
362 int dm_register_target(struct target_type *t);
363 void dm_unregister_target(struct target_type *t);
364
365 /*
366 * Target argument parsing.
367 */
368 struct dm_arg_set {
369 unsigned argc;
370 char **argv;
371 };
372
373 /*
374 * The minimum and maximum value of a numeric argument, together with
375 * the error message to use if the number is found to be outside that range.
376 */
377 struct dm_arg {
378 unsigned min;
379 unsigned max;
380 char *error;
381 };
382
383 /*
384 * Validate the next argument, either returning it as *value or, if invalid,
385 * returning -EINVAL and setting *error.
386 */
387 int dm_read_arg(const struct dm_arg *arg, struct dm_arg_set *arg_set,
388 unsigned *value, char **error);
389
390 /*
391 * Process the next argument as the start of a group containing between
392 * arg->min and arg->max further arguments. Either return the size as
393 * *num_args or, if invalid, return -EINVAL and set *error.
394 */
395 int dm_read_arg_group(const struct dm_arg *arg, struct dm_arg_set *arg_set,
396 unsigned *num_args, char **error);
397
398 /*
399 * Return the current argument and shift to the next.
400 */
401 const char *dm_shift_arg(struct dm_arg_set *as);
402
403 /*
404 * Move through num_args arguments.
405 */
406 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
407
408 /*-----------------------------------------------------------------
409 * Functions for creating and manipulating mapped devices.
410 * Drop the reference with dm_put when you finish with the object.
411 *---------------------------------------------------------------*/
412
413 /*
414 * DM_ANY_MINOR chooses the next available minor number.
415 */
416 #define DM_ANY_MINOR (-1)
417 int dm_create(int minor, struct mapped_device **md);
418
419 /*
420 * Reference counting for md.
421 */
422 struct mapped_device *dm_get_md(dev_t dev);
423 void dm_get(struct mapped_device *md);
424 int dm_hold(struct mapped_device *md);
425 void dm_put(struct mapped_device *md);
426
427 /*
428 * An arbitrary pointer may be stored alongside a mapped device.
429 */
430 void dm_set_mdptr(struct mapped_device *md, void *ptr);
431 void *dm_get_mdptr(struct mapped_device *md);
432
433 /*
434 * A device can still be used while suspended, but I/O is deferred.
435 */
436 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
437 int dm_resume(struct mapped_device *md);
438
439 /*
440 * Event functions.
441 */
442 uint32_t dm_get_event_nr(struct mapped_device *md);
443 int dm_wait_event(struct mapped_device *md, int event_nr);
444 uint32_t dm_next_uevent_seq(struct mapped_device *md);
445 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
446
447 /*
448 * Info functions.
449 */
450 const char *dm_device_name(struct mapped_device *md);
451 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
452 struct gendisk *dm_disk(struct mapped_device *md);
453 int dm_suspended(struct dm_target *ti);
454 int dm_noflush_suspending(struct dm_target *ti);
455 void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors);
456 void dm_remap_zone_report(struct dm_target *ti, struct bio *bio,
457 sector_t start);
458 union map_info *dm_get_rq_mapinfo(struct request *rq);
459
460 struct queue_limits *dm_get_queue_limits(struct mapped_device *md);
461
462 /*
463 * Geometry functions.
464 */
465 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
466 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
467
468 /*-----------------------------------------------------------------
469 * Functions for manipulating device-mapper tables.
470 *---------------------------------------------------------------*/
471
472 /*
473 * First create an empty table.
474 */
475 int dm_table_create(struct dm_table **result, fmode_t mode,
476 unsigned num_targets, struct mapped_device *md);
477
478 /*
479 * Then call this once for each target.
480 */
481 int dm_table_add_target(struct dm_table *t, const char *type,
482 sector_t start, sector_t len, char *params);
483
484 /*
485 * Target_ctr should call this if it needs to add any callbacks.
486 */
487 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
488
489 /*
490 * Target can use this to set the table's type.
491 * Can only ever be called from a target's ctr.
492 * Useful for "hybrid" target (supports both bio-based
493 * and request-based).
494 */
495 void dm_table_set_type(struct dm_table *t, enum dm_queue_mode type);
496
497 /*
498 * Finally call this to make the table ready for use.
499 */
500 int dm_table_complete(struct dm_table *t);
501
502 /*
503 * Target may require that it is never sent I/O larger than len.
504 */
505 int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
506
507 /*
508 * Table reference counting.
509 */
510 struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx);
511 void dm_put_live_table(struct mapped_device *md, int srcu_idx);
512 void dm_sync_table(struct mapped_device *md);
513
514 /*
515 * Queries
516 */
517 sector_t dm_table_get_size(struct dm_table *t);
518 unsigned int dm_table_get_num_targets(struct dm_table *t);
519 fmode_t dm_table_get_mode(struct dm_table *t);
520 struct mapped_device *dm_table_get_md(struct dm_table *t);
521
522 /*
523 * Trigger an event.
524 */
525 void dm_table_event(struct dm_table *t);
526
527 /*
528 * Run the queue for request-based targets.
529 */
530 void dm_table_run_md_queue_async(struct dm_table *t);
531
532 /*
533 * The device must be suspended before calling this method.
534 * Returns the previous table, which the caller must destroy.
535 */
536 struct dm_table *dm_swap_table(struct mapped_device *md,
537 struct dm_table *t);
538
539 /*
540 * A wrapper around vmalloc.
541 */
542 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
543
544 /*-----------------------------------------------------------------
545 * Macros.
546 *---------------------------------------------------------------*/
547 #define DM_NAME "device-mapper"
548
549 #define DM_RATELIMIT(pr_func, fmt, ...) \
550 do { \
551 static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, \
552 DEFAULT_RATELIMIT_BURST); \
553 \
554 if (__ratelimit(&rs)) \
555 pr_func(DM_FMT(fmt), ##__VA_ARGS__); \
556 } while (0)
557
558 #define DM_FMT(fmt) DM_NAME ": " DM_MSG_PREFIX ": " fmt "\n"
559
560 #define DMCRIT(fmt, ...) pr_crit(DM_FMT(fmt), ##__VA_ARGS__)
561
562 #define DMERR(fmt, ...) pr_err(DM_FMT(fmt), ##__VA_ARGS__)
563 #define DMERR_LIMIT(fmt, ...) DM_RATELIMIT(pr_err, fmt, ##__VA_ARGS__)
564 #define DMWARN(fmt, ...) pr_warn(DM_FMT(fmt), ##__VA_ARGS__)
565 #define DMWARN_LIMIT(fmt, ...) DM_RATELIMIT(pr_warn, fmt, ##__VA_ARGS__)
566 #define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
567 #define DMINFO_LIMIT(fmt, ...) DM_RATELIMIT(pr_info, fmt, ##__VA_ARGS__)
568
569 #ifdef CONFIG_DM_DEBUG
570 #define DMDEBUG(fmt, ...) printk(KERN_DEBUG DM_FMT(fmt), ##__VA_ARGS__)
571 #define DMDEBUG_LIMIT(fmt, ...) DM_RATELIMIT(pr_debug, fmt, ##__VA_ARGS__)
572 #else
573 #define DMDEBUG(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
574 #define DMDEBUG_LIMIT(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
575 #endif
576
577 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
578 0 : scnprintf(result + sz, maxlen - sz, x))
579
580 #define SECTOR_SHIFT 9
581
582 /*
583 * Definitions of return values from target end_io function.
584 */
585 #define DM_ENDIO_DONE 0
586 #define DM_ENDIO_INCOMPLETE 1
587 #define DM_ENDIO_REQUEUE 2
588
589 /*
590 * Definitions of return values from target map function.
591 */
592 #define DM_MAPIO_SUBMITTED 0
593 #define DM_MAPIO_REMAPPED 1
594 #define DM_MAPIO_REQUEUE DM_ENDIO_REQUEUE
595 #define DM_MAPIO_DELAY_REQUEUE 3
596 #define DM_MAPIO_KILL 4
597
598 #define dm_sector_div64(x, y)( \
599 { \
600 u64 _res; \
601 (x) = div64_u64_rem(x, y, &_res); \
602 _res; \
603 } \
604 )
605
606 /*
607 * Ceiling(n / sz)
608 */
609 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
610
611 #define dm_sector_div_up(n, sz) ( \
612 { \
613 sector_t _r = ((n) + (sz) - 1); \
614 sector_div(_r, (sz)); \
615 _r; \
616 } \
617 )
618
619 /*
620 * ceiling(n / size) * size
621 */
622 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
623
624 #define dm_array_too_big(fixed, obj, num) \
625 ((num) > (UINT_MAX - (fixed)) / (obj))
626
627 /*
628 * Sector offset taken relative to the start of the target instead of
629 * relative to the start of the device.
630 */
631 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
632
to_sector(unsigned long long n)633 static inline sector_t to_sector(unsigned long long n)
634 {
635 return (n >> SECTOR_SHIFT);
636 }
637
to_bytes(sector_t n)638 static inline unsigned long to_bytes(sector_t n)
639 {
640 return (n << SECTOR_SHIFT);
641 }
642
643 #endif /* _LINUX_DEVICE_MAPPER_H */
644