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 #include <linux/bio.h>
  14
  15 struct dm_target;
  16 struct dm_table;
  17 struct dm_dev;
  18 struct mapped_device;
  19
  20 typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
  21
  22 union map_info {
  23         void *ptr;
  24         unsigned long long ll;
  25 };
  26
  27 /*
  28  * In the constructor the target parameter will already have the
  29  * table, type, begin and len fields filled in.
  30  */
  31 typedef int (*dm_ctr_fn) (struct dm_target *target,
  32                           unsigned int argc, char **argv);
  33
  34 /*
  35  * The destructor doesn't need to free the dm_target, just
  36  * anything hidden ti->private.
  37  */
  38 typedef void (*dm_dtr_fn) (struct dm_target *ti);
  39
  40 /*
  41  * The map function must return:
  42  * < 0: error
  43  * = 0: The target will handle the io by resubmitting it later
  44  * = 1: simple remap complete
  45  * = 2: The target wants to push back the io
  46  */
  47 typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
  48                           union map_info *map_context);
  49
  50 /*
  51  * Returns:
  52  * < 0 : error (currently ignored)
  53  * 0   : ended successfully
  54  * 1   : for some reason the io has still not completed (eg,
  55  *       multipath target might want to requeue a failed io).
  56  * 2   : The target wants to push back the io
  57  */
  58 typedef int (*dm_endio_fn) (struct dm_target *ti,
  59                             struct bio *bio, int error,
  60                             union map_info *map_context);
  61
  62 typedef void (*dm_flush_fn) (struct dm_target *ti);
  63 typedef void (*dm_presuspend_fn) (struct dm_target *ti);
  64 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  65 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  66 typedef void (*dm_resume_fn) (struct dm_target *ti);
  67
  68 typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  69                              char *result, unsigned int maxlen);
  70
  71 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  72
  73 typedef int (*dm_ioctl_fn) (struct dm_target *ti, struct inode *inode,
  74                             struct file *filp, unsigned int cmd,
  75                             unsigned long arg);
  76
  77 void dm_error(const char *message);
  78
  79 /*
  80  * Combine device limits.
  81  */
  82 void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev);
  83
  84 /*
  85  * Constructors should call these functions to ensure destination devices
  86  * are opened/closed correctly.
  87  * FIXME: too many arguments.
  88  */
  89 int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
  90                   sector_t len, int mode, struct dm_dev **result);
  91 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
  92
  93 /*
  94  * Information about a target type
  95  */
  96 struct target_type {
  97         const char *name;
  98         struct module *module;
  99         unsigned version[3];
 100         dm_ctr_fn ctr;
 101         dm_dtr_fn dtr;
 102         dm_map_fn map;
 103         dm_endio_fn end_io;
 104         dm_flush_fn flush;
 105         dm_presuspend_fn presuspend;
 106         dm_postsuspend_fn postsuspend;
 107         dm_preresume_fn preresume;
 108         dm_resume_fn resume;
 109         dm_status_fn status;
 110         dm_message_fn message;
 111         dm_ioctl_fn ioctl;
 112 };
 113
 114 struct io_restrictions {
 115         unsigned long bounce_pfn;
 116         unsigned long seg_boundary_mask;
 117         unsigned max_hw_sectors;
 118         unsigned max_sectors;
 119         unsigned max_segment_size;
 120         unsigned short hardsect_size;
 121         unsigned short max_hw_segments;
 122         unsigned short max_phys_segments;
 123         unsigned char no_cluster; /* inverted so that 0 is default */
 124 };
 125
 126 struct dm_target {
 127         struct dm_table *table;
 128         struct target_type *type;
 129
 130         /* target limits */
 131         sector_t begin;
 132         sector_t len;
 133
 134         /* FIXME: turn this into a mask, and merge with io_restrictions */
 135         /* Always a power of 2 */
 136         sector_t split_io;
 137
 138         /*
 139          * These are automatically filled in by
 140          * dm_table_get_device.
 141          */
 142         struct io_restrictions limits;
 143
 144         /* target specific data */
 145         void *private;
 146
 147         /* Used to provide an error string from the ctr */
 148         char *error;
 149 };
 150
 151 int dm_register_target(struct target_type *t);
 152 int dm_unregister_target(struct target_type *t);
 153
 154
 155 /*-----------------------------------------------------------------
 156  * Functions for creating and manipulating mapped devices.
 157  * Drop the reference with dm_put when you finish with the object.
 158  *---------------------------------------------------------------*/
 159
 160 /*
 161  * DM_ANY_MINOR chooses the next available minor number.
 162  */
 163 #define DM_ANY_MINOR (-1)
 164 int dm_create(int minor, struct mapped_device **md);
 165
 166 /*
 167  * Reference counting for md.
 168  */
 169 struct mapped_device *dm_get_md(dev_t dev);
 170 void dm_get(struct mapped_device *md);
 171 void dm_put(struct mapped_device *md);
 172
 173 /*
 174  * An arbitrary pointer may be stored alongside a mapped device.
 175  */
 176 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 177 void *dm_get_mdptr(struct mapped_device *md);
 178
 179 /*
 180  * A device can still be used while suspended, but I/O is deferred.
 181  */
 182 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
 183 int dm_resume(struct mapped_device *md);
 184
 185 /*
 186  * Event functions.
 187  */
 188 uint32_t dm_get_event_nr(struct mapped_device *md);
 189 int dm_wait_event(struct mapped_device *md, int event_nr);
 190 uint32_t dm_next_uevent_seq(struct mapped_device *md);
 191 void dm_uevent_add(struct mapped_device *md, struct list_head *elist);
 192
 193 /*
 194  * Info functions.
 195  */
 196 const char *dm_device_name(struct mapped_device *md);
 197 int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
 198 struct gendisk *dm_disk(struct mapped_device *md);
 199 int dm_suspended(struct mapped_device *md);
 200 int dm_noflush_suspending(struct dm_target *ti);
 201
 202 /*
 203  * Geometry functions.
 204  */
 205 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 206 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 207
 208
 209 /*-----------------------------------------------------------------
 210  * Functions for manipulating device-mapper tables.
 211  *---------------------------------------------------------------*/
 212
 213 /*
 214  * First create an empty table.
 215  */
 216 int dm_table_create(struct dm_table **result, int mode,
 217                     unsigned num_targets, struct mapped_device *md);
 218
 219 /*
 220  * Then call this once for each target.
 221  */
 222 int dm_table_add_target(struct dm_table *t, const char *type,
 223                         sector_t start, sector_t len, char *params);
 224
 225 /*
 226  * Finally call this to make the table ready for use.
 227  */
 228 int dm_table_complete(struct dm_table *t);
 229
 230 /*
 231  * Table reference counting.
 232  */
 233 struct dm_table *dm_get_table(struct mapped_device *md);
 234 void dm_table_get(struct dm_table *t);
 235 void dm_table_put(struct dm_table *t);
 236
 237 /*
 238  * Queries
 239  */
 240 sector_t dm_table_get_size(struct dm_table *t);
 241 unsigned int dm_table_get_num_targets(struct dm_table *t);
 242 int dm_table_get_mode(struct dm_table *t);
 243 struct mapped_device *dm_table_get_md(struct dm_table *t);
 244
 245 /*
 246  * Trigger an event.
 247  */
 248 void dm_table_event(struct dm_table *t);
 249
 250 /*
 251  * The device must be suspended before calling this method.
 252  */
 253 int dm_swap_table(struct mapped_device *md, struct dm_table *t);
 254
 255 /*
 256  * Prepare a table for a device that will error all I/O.
 257  * To make it active, call dm_suspend(), dm_swap_table() then dm_resume().
 258  */
 259 int dm_create_error_table(struct dm_table **result, struct mapped_device *md);
 260
 261 #endif  /* __KERNEL__ */
 262 #endif  /* _LINUX_DEVICE_MAPPER_H */