include/linux/device-mapper.h

   1 /*
   2  * Copyright (C) 2001 Sistina Software (UK) Limited.
   3  * Copyright (C) 2004 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 #ifdef __KERNEL__
  12
  13 struct dm_target;
  14 struct dm_table;
  15 struct dm_dev;
  16 struct mapped_device;
  17
  18 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  19
  20 union map_info {
  21         void *ptr;
  22         unsigned long long ll;
  23 };
  24
  25 /*
  26  * In the constructor the target parameter will already have the
  27  * table, type, begin and len fields filled in.
  28  */
  29 typedef int (*dm_ctr_fn) (struct dm_target *target,
  30                           unsigned int argc, char **argv);
  31
  32 /*
  33  * The destructor doesn't need to free the dm_target, just
  34  * anything hidden ti->private.
  35  */
  36 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  37
  38 /*
  39  * The map function must return:
  40  * < 0: error
  41  * = 0: The target will handle the io by resubmitting it later
  42  * = 1: simple remap complete
  43  * = 2: The target wants to push back the io
  44  */
  45 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
  46                           union map_info *map_context);
  47
  48 /*
  49  * Returns:
  50  * < 0 : error (currently ignored)
  51  * 0   : ended successfully
  52  * 1   : for some reason the io has still not completed (eg,
  53  *       multipath target might want to requeue a failed io).
  54  * 2   : The target wants to push back the io
  55  */
  56 typedef int (*dm_endio_fn) (struct dm_target *ti,
  57                             struct bio *bio, int error,
  58                             union map_info *map_context);
  59
  60 typedef void (*dm_flush_fn) (struct dm_target *ti);
  61 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  62 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  63 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  64 typedef void (*dm_resume_fn) (struct dm_target *ti);
  65
  66 typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  67                              char *result, unsigned int maxlen);
  68
  69 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  70
  71 typedef int (*dm_ioctl_fn) (struct dm_target *ti, struct inode *inode,
  72                             struct file *filp, unsigned int cmd,
  73                             unsigned long arg);
  74
  75 void dm_error(const char *message);
  76
  77 /*
  78  * Combine device limits.
  79  */
  80 void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev);
  81
  82 /*
  83  * Constructors should call these functions to ensure destination devices
  84  * are opened/closed correctly.
  85  * FIXME: too many arguments.
  86  */
  87 int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
  88                   sector_t len, int mode, struct dm_dev **result);
  89 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
  90
  91 /*
  92  * Information about a target type
  93  */
  94 struct target_type {
  95         const char *name;
  96         struct module *module;
  97         unsigned version[3];
  98         dm_ctr_fn ctr;
  99         dm_dtr_fn dtr;
 100         dm_map_fn map;
 101         dm_endio_fn end_io;
 102         dm_flush_fn flush;
 103         dm_presuspend_fn presuspend;
 104         dm_postsuspend_fn postsuspend;
 105         dm_preresume_fn preresume;
 106         dm_resume_fn resume;
 107         dm_status_fn status;
 108         dm_message_fn message;
 109         dm_ioctl_fn ioctl;
 110 };
 111
 112 struct io_restrictions {
 113         unsigned int            max_sectors;
 114         unsigned short          max_phys_segments;
 115         unsigned short          max_hw_segments;
 116         unsigned short          hardsect_size;
 117         unsigned int            max_segment_size;
 118         unsigned long           seg_boundary_mask;
 119         unsigned char           no_cluster; /* inverted so that 0 is default */
 120 };
 121
 122 struct dm_target {
 123         struct dm_table *table;
 124         struct target_type *type;
 125
 126         /* target limits */
 127         sector_t begin;
 128         sector_t len;
 129
 130         /* FIXME: turn this into a mask, and merge with io_restrictions */
 131         /* Always a power of 2 */
 132         sector_t split_io;
 133
 134         /*
 135          * These are automatically filled in by
 136          * dm_table_get_device.
 137          */
 138         struct io_restrictions limits;
 139
 140         /* target specific data */
 141         void *private;
 142
 143         /* Used to provide an error string from the ctr */
 144         char *error;
 145 };
 146
 147 int dm_register_target(struct target_type *t);
 148 int dm_unregister_target(struct target_type *t);
 149
 150
 151 /*-----------------------------------------------------------------
 152  * Functions for creating and manipulating mapped devices.
 153  * Drop the reference with dm_put when you finish with the object.
 154  *---------------------------------------------------------------*/
 155
 156 /*
 157  * DM_ANY_MINOR chooses the next available minor number.
 158  */
 159 #define DM_ANY_MINOR (-1)
 160 int dm_create(int minor, struct mapped_device **md);
 161
 162 /*
 163  * Reference counting for md.
 164  */
 165 struct mapped_device *dm_get_md(dev_t dev);
 166 void dm_get(struct mapped_device *md);
 167 void dm_put(struct mapped_device *md);
 168
 169 /*
 170  * An arbitrary pointer may be stored alongside a mapped device.
 171  */
 172 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 173 void *dm_get_mdptr(struct mapped_device *md);
 174
 175 /*
 176  * A device can still be used while suspended, but I/O is deferred.
 177  */
 178 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 179 int dm_resume(struct mapped_device *md);
 180
 181 /*
 182  * Event functions.
 183  */
 184 uint32_t dm_get_event_nr(struct mapped_device *md);
 185 int dm_wait_event(struct mapped_device *md, int event_nr);
 186
 187 /*
 188  * Info functions.
 189  */
 190 const char *dm_device_name(struct mapped_device *md);
 191 struct gendisk *dm_disk(struct mapped_device *md);
 192 int dm_suspended(struct mapped_device *md);
 193 int dm_noflush_suspending(struct dm_target *ti);
 194
 195 /*
 196  * Geometry functions.
 197  */
 198 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 199 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 200
 201
 202 /*-----------------------------------------------------------------
 203  * Functions for manipulating device-mapper tables.
 204  *---------------------------------------------------------------*/
 205
 206 /*
 207  * First create an empty table.
 208  */
 209 int dm_table_create(struct dm_table **result, int mode,
 210                     unsigned num_targets, struct mapped_device *md);
 211
 212 /*
 213  * Then call this once for each target.
 214  */
 215 int dm_table_add_target(struct dm_table *t, const char *type,
 216                         sector_t start, sector_t len, char *params);
 217
 218 /*
 219  * Finally call this to make the table ready for use.
 220  */
 221 int dm_table_complete(struct dm_table *t);
 222
 223 /*
 224  * Table reference counting.
 225  */
 226 struct dm_table *dm_get_table(struct mapped_device *md);
 227 void dm_table_get(struct dm_table *t);
 228 void dm_table_put(struct dm_table *t);
 229
 230 /*
 231  * Queries
 232  */
 233 sector_t dm_table_get_size(struct dm_table *t);
 234 unsigned int dm_table_get_num_targets(struct dm_table *t);
 235 int dm_table_get_mode(struct dm_table *t);
 236 struct mapped_device *dm_table_get_md(struct dm_table *t);
 237
 238 /*
 239  * Trigger an event.
 240  */
 241 void dm_table_event(struct dm_table *t);
 242
 243 /*
 244  * The device must be suspended before calling this method.
 245  */
 246 int dm_swap_table(struct mapped_device *md, struct dm_table *t);
 247
 248 /*
 249  * Prepare a table for a device that will error all I/O.
 250  * To make it active, call dm_suspend(), dm_swap_table() then dm_resume().
 251  */
 252 int dm_create_error_table(struct dm_table **result, struct mapped_device *md);
 253
 254 #endif  /* __KERNEL__ */
 255 #endif  /* _LINUX_DEVICE_MAPPER_H */