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