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_presuspend_fn) (struct dm_target *ti);
  59 typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
  60 typedef int (*dm_preresume_fn) (struct dm_target *ti);
  61 typedef void (*dm_resume_fn) (struct dm_target *ti);
  62
  63 typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
  64                              char *result, unsigned int maxlen);
  65
  66 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
  67
  68 typedef int (*dm_ioctl_fn) (struct dm_target *ti, struct inode *inode,
  69                             struct file *filp, unsigned int cmd,
  70                             unsigned long arg);
  71
  72 void dm_error(const char *message);
  73
  74 /*
  75  * Combine device limits.
  76  */
  77 void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev);
  78
  79 /*
  80  * Constructors should call these functions to ensure destination devices
  81  * are opened/closed correctly.
  82  * FIXME: too many arguments.
  83  */
  84 int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
  85                   sector_t len, int mode, struct dm_dev **result);
  86 void dm_put_device(struct dm_target *ti, struct dm_dev *d);
  87
  88 /*
  89  * Information about a target type
  90  */
  91 struct target_type {
  92         const char *name;
  93         struct module *module;
  94         unsigned version[3];
  95         dm_ctr_fn ctr;
  96         dm_dtr_fn dtr;
  97         dm_map_fn map;
  98         dm_endio_fn end_io;
  99         dm_presuspend_fn presuspend;
 100         dm_postsuspend_fn postsuspend;
 101         dm_preresume_fn preresume;
 102         dm_resume_fn resume;
 103         dm_status_fn status;
 104         dm_message_fn message;
 105         dm_ioctl_fn ioctl;
 106 };
 107
 108 struct io_restrictions {
 109         unsigned int            max_sectors;
 110         unsigned short          max_phys_segments;
 111         unsigned short          max_hw_segments;
 112         unsigned short          hardsect_size;
 113         unsigned int            max_segment_size;
 114         unsigned long           seg_boundary_mask;
 115         unsigned char           no_cluster; /* inverted so that 0 is default */
 116 };
 117
 118 struct dm_target {
 119         struct dm_table *table;
 120         struct target_type *type;
 121
 122         /* target limits */
 123         sector_t begin;
 124         sector_t len;
 125
 126         /* FIXME: turn this into a mask, and merge with io_restrictions */
 127         /* Always a power of 2 */
 128         sector_t split_io;
 129
 130         /*
 131          * These are automatically filled in by
 132          * dm_table_get_device.
 133          */
 134         struct io_restrictions limits;
 135
 136         /* target specific data */
 137         void *private;
 138
 139         /* Used to provide an error string from the ctr */
 140         char *error;
 141 };
 142
 143 int dm_register_target(struct target_type *t);
 144 int dm_unregister_target(struct target_type *t);
 145
 146
 147 /*-----------------------------------------------------------------
 148  * Functions for creating and manipulating mapped devices.
 149  * Drop the reference with dm_put when you finish with the object.
 150  *---------------------------------------------------------------*/
 151
 152 /*
 153  * DM_ANY_MINOR chooses the next available minor number.
 154  */
 155 #define DM_ANY_MINOR (-1)
 156 int dm_create(int minor, struct mapped_device **md);
 157
 158 /*
 159  * Reference counting for md.
 160  */
 161 struct mapped_device *dm_get_md(dev_t dev);
 162 void dm_get(struct mapped_device *md);
 163 void dm_put(struct mapped_device *md);
 164
 165 /*
 166  * An arbitrary pointer may be stored alongside a mapped device.
 167  */
 168 void dm_set_mdptr(struct mapped_device *md, void *ptr);
 169 void *dm_get_mdptr(struct mapped_device *md);
 170
 171 /*
 172  * A device can still be used while suspended, but I/O is deferred.
 173  */
 174 int dm_suspend(struct mapped_device *md, int with_lockfs);
 175 int dm_resume(struct mapped_device *md);
 176
 177 /*
 178  * Event functions.
 179  */
 180 uint32_t dm_get_event_nr(struct mapped_device *md);
 181 int dm_wait_event(struct mapped_device *md, int event_nr);
 182
 183 /*
 184  * Info functions.
 185  */
 186 const char *dm_device_name(struct mapped_device *md);
 187 struct gendisk *dm_disk(struct mapped_device *md);
 188 int dm_suspended(struct mapped_device *md);
 189
 190 /*
 191  * Geometry functions.
 192  */
 193 int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
 194 int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);
 195
 196
 197 /*-----------------------------------------------------------------
 198  * Functions for manipulating device-mapper tables.
 199  *---------------------------------------------------------------*/
 200
 201 /*
 202  * First create an empty table.
 203  */
 204 int dm_table_create(struct dm_table **result, int mode,
 205                     unsigned num_targets, struct mapped_device *md);
 206
 207 /*
 208  * Then call this once for each target.
 209  */
 210 int dm_table_add_target(struct dm_table *t, const char *type,
 211                         sector_t start, sector_t len, char *params);
 212
 213 /*
 214  * Finally call this to make the table ready for use.
 215  */
 216 int dm_table_complete(struct dm_table *t);
 217
 218 /*
 219  * Table reference counting.
 220  */
 221 struct dm_table *dm_get_table(struct mapped_device *md);
 222 void dm_table_get(struct dm_table *t);
 223 void dm_table_put(struct dm_table *t);
 224
 225 /*
 226  * Queries
 227  */
 228 sector_t dm_table_get_size(struct dm_table *t);
 229 unsigned int dm_table_get_num_targets(struct dm_table *t);
 230 int dm_table_get_mode(struct dm_table *t);
 231 struct mapped_device *dm_table_get_md(struct dm_table *t);
 232
 233 /*
 234  * Trigger an event.
 235  */
 236 void dm_table_event(struct dm_table *t);
 237
 238 /*
 239  * The device must be suspended before calling this method.
 240  */
 241 int dm_swap_table(struct mapped_device *md, struct dm_table *t);
 242
 243 /*
 244  * Prepare a table for a device that will error all I/O.
 245  * To make it active, call dm_suspend(), dm_swap_table() then dm_resume().
 246  */
 247 int dm_create_error_table(struct dm_table **result, struct mapped_device *md);
 248
 249 #endif  /* __KERNEL__ */
 250 #endif  /* _LINUX_DEVICE_MAPPER_H */