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TOMOYO Linux Cross Reference
Linux/include/linux/device-mapper.h

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

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