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/ratelimit.h>
14
15 struct dm_dev;
16 struct dm_target;
17 struct dm_table;
18 struct mapped_device;
19 struct bio_vec;
20
21 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
22
23 union map_info {
24 void *ptr;
25 unsigned long long ll;
26 unsigned target_request_nr;
27 };
28
29 /*
30 * In the constructor the target parameter will already have the
31 * table, type, begin and len fields filled in.
32 */
33 typedef int (*dm_ctr_fn) (struct dm_target *target,
34 unsigned int argc, char **argv);
35
36 /*
37 * The destructor doesn't need to free the dm_target, just
38 * anything hidden ti->private.
39 */
40 typedef void (*dm_dtr_fn) (struct dm_target *ti);
41
42 /*
43 * The map function must return:
44 * < 0: error
45 * = 0: The target will handle the io by resubmitting it later
46 * = 1: simple remap complete
47 * = 2: The target wants to push back the io
48 */
49 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
50 union map_info *map_context);
51 typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone,
52 union map_info *map_context);
53
54 /*
55 * Returns:
56 * < 0 : error (currently ignored)
57 * 0 : ended successfully
58 * 1 : for some reason the io has still not completed (eg,
59 * multipath target might want to requeue a failed io).
60 * 2 : The target wants to push back the io
61 */
62 typedef int (*dm_endio_fn) (struct dm_target *ti,
63 struct bio *bio, int error,
64 union map_info *map_context);
65 typedef int (*dm_request_endio_fn) (struct dm_target *ti,
66 struct request *clone, int error,
67 union map_info *map_context);
68
69 typedef void (*dm_flush_fn) (struct dm_target *ti);
70 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
71 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
72 typedef int (*dm_preresume_fn) (struct dm_target *ti);
73 typedef void (*dm_resume_fn) (struct dm_target *ti);
74
75 typedef void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
76 char *result, unsigned int maxlen);
77
78 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
79
80 typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
81 unsigned long arg);
82
83 typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
84 struct bio_vec *biovec, int max_size);
85
86 typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
87 struct dm_dev *dev,
88 sector_t start, sector_t len,
89 void *data);
90
91 typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
92 iterate_devices_callout_fn fn,
93 void *data);
94
95 typedef void (*dm_io_hints_fn) (struct dm_target *ti,
96 struct queue_limits *limits);
97
98 /*
99 * Returns:
100 * 0: The target can handle the next I/O immediately.
101 * 1: The target can't handle the next I/O immediately.
102 */
103 typedef int (*dm_busy_fn) (struct dm_target *ti);
104
105 void dm_error(const char *message);
106
107 /*
108 * Combine device limits.
109 */
110 int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
111 sector_t start, sector_t len, void *data);
112
113 struct dm_dev {
114 struct block_device *bdev;
115 fmode_t mode;
116 char name[16];
117 };
118
119 /*
120 * Constructors should call these functions to ensure destination devices
121 * are opened/closed correctly.
122 */
123 int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
124 struct dm_dev **result);
125 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
126
127 /*
128 * Information about a target type
129 */
130
131 struct target_type {
132 uint64_t features;
133 const char *name;
134 struct module *module;
135 unsigned version[3];
136 dm_ctr_fn ctr;
137 dm_dtr_fn dtr;
138 dm_map_fn map;
139 dm_map_request_fn map_rq;
140 dm_endio_fn end_io;
141 dm_request_endio_fn rq_end_io;
142 dm_flush_fn flush;
143 dm_presuspend_fn presuspend;
144 dm_postsuspend_fn postsuspend;
145 dm_preresume_fn preresume;
146 dm_resume_fn resume;
147 dm_status_fn status;
148 dm_message_fn message;
149 dm_ioctl_fn ioctl;
150 dm_merge_fn merge;
151 dm_busy_fn busy;
152 dm_iterate_devices_fn iterate_devices;
153 dm_io_hints_fn io_hints;
154
155 /* For internal device-mapper use. */
156 struct list_head list;
157 };
158
159 /*
160 * Target features
161 */
162
163 /*
164 * Any table that contains an instance of this target must have only one.
165 */
166 #define DM_TARGET_SINGLETON 0x00000001
167 #define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON)
168
169 /*
170 * Indicates that a target does not support read-only devices.
171 */
172 #define DM_TARGET_ALWAYS_WRITEABLE 0x00000002
173 #define dm_target_always_writeable(type) \
174 ((type)->features & DM_TARGET_ALWAYS_WRITEABLE)
175
176 /*
177 * Any device that contains a table with an instance of this target may never
178 * have tables containing any different target type.
179 */
180 #define DM_TARGET_IMMUTABLE 0x00000004
181 #define dm_target_is_immutable(type) ((type)->features & DM_TARGET_IMMUTABLE)
182
183 struct dm_target {
184 struct dm_table *table;
185 struct target_type *type;
186
187 /* target limits */
188 sector_t begin;
189 sector_t len;
190
191 /* Always a power of 2 */
192 sector_t split_io;
193
194 /*
195 * A number of zero-length barrier requests that will be submitted
196 * to the target for the purpose of flushing cache.
197 *
198 * The request number will be placed in union map_info->target_request_nr.
199 * It is a responsibility of the target driver to remap these requests
200 * to the real underlying devices.
201 */
202 unsigned num_flush_requests;
203
204 /*
205 * The number of discard requests that will be submitted to the
206 * target. map_info->request_nr is used just like num_flush_requests.
207 */
208 unsigned num_discard_requests;
209
210 /* target specific data */
211 void *private;
212
213 /* Used to provide an error string from the ctr */
214 char *error;
215
216 /*
217 * Set if this target needs to receive discards regardless of
218 * whether or not its underlying devices have support.
219 */
220 unsigned discards_supported:1;
221
222 /*
223 * Set if this target does not return zeroes on discarded blocks.
224 */
225 unsigned discard_zeroes_data_unsupported:1;
226 };
227
228 /* Each target can link one of these into the table */
229 struct dm_target_callbacks {
230 struct list_head list;
231 int (*congested_fn) (struct dm_target_callbacks *, int);
232 };
233
234 int dm_register_target(struct target_type *t);
235 void dm_unregister_target(struct target_type *t);
236
237 /*
238 * Target argument parsing.
239 */
240 struct dm_arg_set {
241 unsigned argc;
242 char **argv;
243 };
244
245 /*
246 * The minimum and maximum value of a numeric argument, together with
247 * the error message to use if the number is found to be outside that range.
248 */
249 struct dm_arg {
250 unsigned min;
251 unsigned max;
252 char *error;
253 };
254
255 /*
256 * Validate the next argument, either returning it as *value or, if invalid,
257 * returning -EINVAL and setting *error.
258 */
259 int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
260 unsigned *value, char **error);
261
262 /*
263 * Process the next argument as the start of a group containing between
264 * arg->min and arg->max further arguments. Either return the size as
265 * *num_args or, if invalid, return -EINVAL and set *error.
266 */
267 int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
268 unsigned *num_args, char **error);
269
270 /*
271 * Return the current argument and shift to the next.
272 */
273 const char *dm_shift_arg(struct dm_arg_set *as);
274
275 /*
276 * Move through num_args arguments.
277 */
278 void dm_consume_args(struct dm_arg_set *as, unsigned num_args);
279
280 /*-----------------------------------------------------------------
281 * Functions for creating and manipulating mapped devices.
282 * Drop the reference with dm_put when you finish with the object.
283 *---------------------------------------------------------------*/
284
285 /*
286 * DM_ANY_MINOR chooses the next available minor number.
287 */
288 #define DM_ANY_MINOR (-1)
289 int dm_create(int minor, struct mapped_device **md);
290
291 /*
292 * Reference counting for md.
293 */
294 struct mapped_device *dm_get_md(dev_t dev);
295 void dm_get(struct mapped_device *md);
296 void dm_put(struct mapped_device *md);
297
298 /*
299 * An arbitrary pointer may be stored alongside a mapped device.
300 */
301 void dm_set_mdptr(struct mapped_device *md, void *ptr);
302 void *dm_get_mdptr(struct mapped_device *md);
303
304 /*
305 * A device can still be used while suspended, but I/O is deferred.
306 */
307 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
308 int dm_resume(struct mapped_device *md);
309
310 /*
311 * Event functions.
312 */
313 uint32_t dm_get_event_nr(struct mapped_device *md);
314 int dm_wait_event(struct mapped_device *md, int event_nr);
315 uint32_t dm_next_uevent_seq(struct mapped_device *md);
316 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
317
318 /*
319 * Info functions.
320 */
321 const char *dm_device_name(struct mapped_device *md);
322 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
323 struct gendisk *dm_disk(struct mapped_device *md);
324 int dm_suspended(struct dm_target *ti);
325 int dm_noflush_suspending(struct dm_target *ti);
326 union map_info *dm_get_mapinfo(struct bio *bio);
327 union map_info *dm_get_rq_mapinfo(struct request *rq);
328
329 /*
330 * Geometry functions.
331 */
332 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
333 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
334
335
336 /*-----------------------------------------------------------------
337 * Functions for manipulating device-mapper tables.
338 *---------------------------------------------------------------*/
339
340 /*
341 * First create an empty table.
342 */
343 int dm_table_create(struct dm_table **result, fmode_t mode,
344 unsigned num_targets, struct mapped_device *md);
345
346 /*
347 * Then call this once for each target.
348 */
349 int dm_table_add_target(struct dm_table *t, const char *type,
350 sector_t start, sector_t len, char *params);
351
352 /*
353 * Target_ctr should call this if it needs to add any callbacks.
354 */
355 void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
356
357 /*
358 * Finally call this to make the table ready for use.
359 */
360 int dm_table_complete(struct dm_table *t);
361
362 /*
363 * Table reference counting.
364 */
365 struct dm_table *dm_get_live_table(struct mapped_device *md);
366 void dm_table_get(struct dm_table *t);
367 void dm_table_put(struct dm_table *t);
368
369 /*
370 * Queries
371 */
372 sector_t dm_table_get_size(struct dm_table *t);
373 unsigned int dm_table_get_num_targets(struct dm_table *t);
374 fmode_t dm_table_get_mode(struct dm_table *t);
375 struct mapped_device *dm_table_get_md(struct dm_table *t);
376
377 /*
378 * Trigger an event.
379 */
380 void dm_table_event(struct dm_table *t);
381
382 /*
383 * The device must be suspended before calling this method.
384 * Returns the previous table, which the caller must destroy.
385 */
386 struct dm_table *dm_swap_table(struct mapped_device *md,
387 struct dm_table *t);
388
389 /*
390 * A wrapper around vmalloc.
391 */
392 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
393
394 /*-----------------------------------------------------------------
395 * Macros.
396 *---------------------------------------------------------------*/
397 #define DM_NAME "device-mapper"
398
399 #ifdef CONFIG_PRINTK
400 extern struct ratelimit_state dm_ratelimit_state;
401
402 #define dm_ratelimit() __ratelimit(&dm_ratelimit_state)
403 #else
404 #define dm_ratelimit() 0
405 #endif
406
407 #define DMCRIT(f, arg...) \
408 printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
409
410 #define DMERR(f, arg...) \
411 printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
412 #define DMERR_LIMIT(f, arg...) \
413 do { \
414 if (dm_ratelimit()) \
415 printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
416 f "\n", ## arg); \
417 } while (0)
418
419 #define DMWARN(f, arg...) \
420 printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
421 #define DMWARN_LIMIT(f, arg...) \
422 do { \
423 if (dm_ratelimit()) \
424 printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
425 f "\n", ## arg); \
426 } while (0)
427
428 #define DMINFO(f, arg...) \
429 printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
430 #define DMINFO_LIMIT(f, arg...) \
431 do { \
432 if (dm_ratelimit()) \
433 printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
434 "\n", ## arg); \
435 } while (0)
436
437 #ifdef CONFIG_DM_DEBUG
438 # define DMDEBUG(f, arg...) \
439 printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
440 # define DMDEBUG_LIMIT(f, arg...) \
441 do { \
442 if (dm_ratelimit()) \
443 printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
444 "\n", ## arg); \
445 } while (0)
446 #else
447 # define DMDEBUG(f, arg...) do {} while (0)
448 # define DMDEBUG_LIMIT(f, arg...) do {} while (0)
449 #endif
450
451 #define DMEMIT(x...) sz += ((sz >= maxlen) ? \
452 0 : scnprintf(result + sz, maxlen - sz, x))
453
454 #define SECTOR_SHIFT 9
455
456 /*
457 * Definitions of return values from target end_io function.
458 */
459 #define DM_ENDIO_INCOMPLETE 1
460 #define DM_ENDIO_REQUEUE 2
461
462 /*
463 * Definitions of return values from target map function.
464 */
465 #define DM_MAPIO_SUBMITTED 0
466 #define DM_MAPIO_REMAPPED 1
467 #define DM_MAPIO_REQUEUE DM_ENDIO_REQUEUE
468
469 /*
470 * Ceiling(n / sz)
471 */
472 #define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))
473
474 #define dm_sector_div_up(n, sz) ( \
475 { \
476 sector_t _r = ((n) + (sz) - 1); \
477 sector_div(_r, (sz)); \
478 _r; \
479 } \
480 )
481
482 /*
483 * ceiling(n / size) * size
484 */
485 #define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))
486
487 #define dm_array_too_big(fixed, obj, num) \
488 ((num) > (UINT_MAX - (fixed)) / (obj))
489
490 /*
491 * Sector offset taken relative to the start of the target instead of
492 * relative to the start of the device.
493 */
494 #define dm_target_offset(ti, sector) ((sector) - (ti)->begin)
495
to_sector(unsigned long n)496 static inline sector_t to_sector(unsigned long n)
497 {
498 return (n >> SECTOR_SHIFT);
499 }
500
to_bytes(sector_t n)501 static inline unsigned long to_bytes(sector_t n)
502 {
503 return (n << SECTOR_SHIFT);
504 }
505
506 /*-----------------------------------------------------------------
507 * Helper for block layer and dm core operations
508 *---------------------------------------------------------------*/
509 void dm_dispatch_request(struct request *rq);
510 void dm_requeue_unmapped_request(struct request *rq);
511 void dm_kill_unmapped_request(struct request *rq, int error);
512 int dm_underlying_device_busy(struct request_queue *q);
513
514 #endif /* _LINUX_DEVICE_MAPPER_H */
515