linux/include/linux/dm-log-userspace.h
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   1/*
   2 * Copyright (C) 2006-2009 Red Hat, Inc.
   3 *
   4 * This file is released under the LGPL.
   5 */
   6
   7#ifndef __DM_LOG_USERSPACE_H__
   8#define __DM_LOG_USERSPACE_H__
   9
  10#include <linux/dm-ioctl.h> /* For DM_UUID_LEN */
  11
  12/*
  13 * The device-mapper userspace log module consists of a kernel component and
  14 * a user-space component.  The kernel component implements the API defined
  15 * in dm-dirty-log.h.  Its purpose is simply to pass the parameters and
  16 * return values of those API functions between kernel and user-space.
  17 *
  18 * Below are defined the 'request_types' - DM_ULOG_CTR, DM_ULOG_DTR, etc.
  19 * These request types represent the different functions in the device-mapper
  20 * dirty log API.  Each of these is described in more detail below.
  21 *
  22 * The user-space program must listen for requests from the kernel (representing
  23 * the various API functions) and process them.
  24 *
  25 * User-space begins by setting up the communication link (error checking
  26 * removed for clarity):
  27 *      fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
  28 *      addr.nl_family = AF_NETLINK;
  29 *      addr.nl_groups = CN_IDX_DM;
  30 *      addr.nl_pid = 0;
  31 *      r = bind(fd, (struct sockaddr *) &addr, sizeof(addr));
  32 *      opt = addr.nl_groups;
  33 *      setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &opt, sizeof(opt));
  34 *
  35 * User-space will then wait to receive requests form the kernel, which it
  36 * will process as described below.  The requests are received in the form,
  37 * ((struct dm_ulog_request) + (additional data)).  Depending on the request
  38 * type, there may or may not be 'additional data'.  In the descriptions below,
  39 * you will see 'Payload-to-userspace' and 'Payload-to-kernel'.  The
  40 * 'Payload-to-userspace' is what the kernel sends in 'additional data' as
  41 * necessary parameters to complete the request.  The 'Payload-to-kernel' is
  42 * the 'additional data' returned to the kernel that contains the necessary
  43 * results of the request.  The 'data_size' field in the dm_ulog_request
  44 * structure denotes the availability and amount of payload data.
  45 */
  46
  47/*
  48 * DM_ULOG_CTR corresponds to (found in dm-dirty-log.h):
  49 * int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
  50 *            unsigned argc, char **argv);
  51 *
  52 * Payload-to-userspace:
  53 *      A single string containing all the argv arguments separated by ' 's
  54 * Payload-to-kernel:
  55 *      A NUL-terminated string that is the name of the device that is used
  56 *      as the backing store for the log data.  'dm_get_device' will be called
  57 *      on this device.  ('dm_put_device' will be called on this device
  58 *      automatically after calling DM_ULOG_DTR.)  If there is no device needed
  59 *      for log data, 'data_size' in the dm_ulog_request struct should be 0.
  60 *
  61 * The UUID contained in the dm_ulog_request structure is the reference that
  62 * will be used by all request types to a specific log.  The constructor must
  63 * record this association with the instance created.
  64 *
  65 * When the request has been processed, user-space must return the
  66 * dm_ulog_request to the kernel - setting the 'error' field, filling the
  67 * data field with the log device if necessary, and setting 'data_size'
  68 * appropriately.
  69 */
  70#define DM_ULOG_CTR                    1
  71
  72/*
  73 * DM_ULOG_DTR corresponds to (found in dm-dirty-log.h):
  74 * void (*dtr)(struct dm_dirty_log *log);
  75 *
  76 * Payload-to-userspace:
  77 *      A single string containing all the argv arguments separated by ' 's
  78 * Payload-to-kernel:
  79 *      None.  ('data_size' in the dm_ulog_request struct should be 0.)
  80 *
  81 * The UUID contained in the dm_ulog_request structure is all that is
  82 * necessary to identify the log instance being destroyed.  There is no
  83 * payload data.
  84 *
  85 * When the request has been processed, user-space must return the
  86 * dm_ulog_request to the kernel - setting the 'error' field and clearing
  87 * 'data_size' appropriately.
  88 */
  89#define DM_ULOG_DTR                    2
  90
  91/*
  92 * DM_ULOG_PRESUSPEND corresponds to (found in dm-dirty-log.h):
  93 * int (*presuspend)(struct dm_dirty_log *log);
  94 *
  95 * Payload-to-userspace:
  96 *      None.
  97 * Payload-to-kernel:
  98 *      None.
  99 *
 100 * The UUID contained in the dm_ulog_request structure is all that is
 101 * necessary to identify the log instance being presuspended.  There is no
 102 * payload data.
 103 *
 104 * When the request has been processed, user-space must return the
 105 * dm_ulog_request to the kernel - setting the 'error' field and
 106 * 'data_size' appropriately.
 107 */
 108#define DM_ULOG_PRESUSPEND             3
 109
 110/*
 111 * DM_ULOG_POSTSUSPEND corresponds to (found in dm-dirty-log.h):
 112 * int (*postsuspend)(struct dm_dirty_log *log);
 113 *
 114 * Payload-to-userspace:
 115 *      None.
 116 * Payload-to-kernel:
 117 *      None.
 118 *
 119 * The UUID contained in the dm_ulog_request structure is all that is
 120 * necessary to identify the log instance being postsuspended.  There is no
 121 * payload data.
 122 *
 123 * When the request has been processed, user-space must return the
 124 * dm_ulog_request to the kernel - setting the 'error' field and
 125 * 'data_size' appropriately.
 126 */
 127#define DM_ULOG_POSTSUSPEND            4
 128
 129/*
 130 * DM_ULOG_RESUME corresponds to (found in dm-dirty-log.h):
 131 * int (*resume)(struct dm_dirty_log *log);
 132 *
 133 * Payload-to-userspace:
 134 *      None.
 135 * Payload-to-kernel:
 136 *      None.
 137 *
 138 * The UUID contained in the dm_ulog_request structure is all that is
 139 * necessary to identify the log instance being resumed.  There is no
 140 * payload data.
 141 *
 142 * When the request has been processed, user-space must return the
 143 * dm_ulog_request to the kernel - setting the 'error' field and
 144 * 'data_size' appropriately.
 145 */
 146#define DM_ULOG_RESUME                 5
 147
 148/*
 149 * DM_ULOG_GET_REGION_SIZE corresponds to (found in dm-dirty-log.h):
 150 * uint32_t (*get_region_size)(struct dm_dirty_log *log);
 151 *
 152 * Payload-to-userspace:
 153 *      None.
 154 * Payload-to-kernel:
 155 *      uint64_t - contains the region size
 156 *
 157 * The region size is something that was determined at constructor time.
 158 * It is returned in the payload area and 'data_size' is set to
 159 * reflect this.
 160 *
 161 * When the request has been processed, user-space must return the
 162 * dm_ulog_request to the kernel - setting the 'error' field appropriately.
 163 */
 164#define DM_ULOG_GET_REGION_SIZE        6
 165
 166/*
 167 * DM_ULOG_IS_CLEAN corresponds to (found in dm-dirty-log.h):
 168 * int (*is_clean)(struct dm_dirty_log *log, region_t region);
 169 *
 170 * Payload-to-userspace:
 171 *      uint64_t - the region to get clean status on
 172 * Payload-to-kernel:
 173 *      int64_t  - 1 if clean, 0 otherwise
 174 *
 175 * Payload is sizeof(uint64_t) and contains the region for which the clean
 176 * status is being made.
 177 *
 178 * When the request has been processed, user-space must return the
 179 * dm_ulog_request to the kernel - filling the payload with 0 (not clean) or
 180 * 1 (clean), setting 'data_size' and 'error' appropriately.
 181 */
 182#define DM_ULOG_IS_CLEAN               7
 183
 184/*
 185 * DM_ULOG_IN_SYNC corresponds to (found in dm-dirty-log.h):
 186 * int (*in_sync)(struct dm_dirty_log *log, region_t region,
 187 *                int can_block);
 188 *
 189 * Payload-to-userspace:
 190 *      uint64_t - the region to get sync status on
 191 * Payload-to-kernel:
 192 *      int64_t - 1 if in-sync, 0 otherwise
 193 *
 194 * Exactly the same as 'is_clean' above, except this time asking "has the
 195 * region been recovered?" vs. "is the region not being modified?"
 196 */
 197#define DM_ULOG_IN_SYNC                8
 198
 199/*
 200 * DM_ULOG_FLUSH corresponds to (found in dm-dirty-log.h):
 201 * int (*flush)(struct dm_dirty_log *log);
 202 *
 203 * Payload-to-userspace:
 204 *      None.
 205 * Payload-to-kernel:
 206 *      None.
 207 *
 208 * No incoming or outgoing payload.  Simply flush log state to disk.
 209 *
 210 * When the request has been processed, user-space must return the
 211 * dm_ulog_request to the kernel - setting the 'error' field and clearing
 212 * 'data_size' appropriately.
 213 */
 214#define DM_ULOG_FLUSH                  9
 215
 216/*
 217 * DM_ULOG_MARK_REGION corresponds to (found in dm-dirty-log.h):
 218 * void (*mark_region)(struct dm_dirty_log *log, region_t region);
 219 *
 220 * Payload-to-userspace:
 221 *      uint64_t [] - region(s) to mark
 222 * Payload-to-kernel:
 223 *      None.
 224 *
 225 * Incoming payload contains the one or more regions to mark dirty.
 226 * The number of regions contained in the payload can be determined from
 227 * 'data_size/sizeof(uint64_t)'.
 228 *
 229 * When the request has been processed, user-space must return the
 230 * dm_ulog_request to the kernel - setting the 'error' field and clearing
 231 * 'data_size' appropriately.
 232 */
 233#define DM_ULOG_MARK_REGION           10
 234
 235/*
 236 * DM_ULOG_CLEAR_REGION corresponds to (found in dm-dirty-log.h):
 237 * void (*clear_region)(struct dm_dirty_log *log, region_t region);
 238 *
 239 * Payload-to-userspace:
 240 *      uint64_t [] - region(s) to clear
 241 * Payload-to-kernel:
 242 *      None.
 243 *
 244 * Incoming payload contains the one or more regions to mark clean.
 245 * The number of regions contained in the payload can be determined from
 246 * 'data_size/sizeof(uint64_t)'.
 247 *
 248 * When the request has been processed, user-space must return the
 249 * dm_ulog_request to the kernel - setting the 'error' field and clearing
 250 * 'data_size' appropriately.
 251 */
 252#define DM_ULOG_CLEAR_REGION          11
 253
 254/*
 255 * DM_ULOG_GET_RESYNC_WORK corresponds to (found in dm-dirty-log.h):
 256 * int (*get_resync_work)(struct dm_dirty_log *log, region_t *region);
 257 *
 258 * Payload-to-userspace:
 259 *      None.
 260 * Payload-to-kernel:
 261 *      {
 262 *              int64_t i; -- 1 if recovery necessary, 0 otherwise
 263 *              uint64_t r; -- The region to recover if i=1
 264 *      }
 265 * 'data_size' should be set appropriately.
 266 *
 267 * When the request has been processed, user-space must return the
 268 * dm_ulog_request to the kernel - setting the 'error' field appropriately.
 269 */
 270#define DM_ULOG_GET_RESYNC_WORK       12
 271
 272/*
 273 * DM_ULOG_SET_REGION_SYNC corresponds to (found in dm-dirty-log.h):
 274 * void (*set_region_sync)(struct dm_dirty_log *log,
 275 *                         region_t region, int in_sync);
 276 *
 277 * Payload-to-userspace:
 278 *      {
 279 *              uint64_t - region to set sync state on
 280 *              int64_t  - 0 if not-in-sync, 1 if in-sync
 281 *      }
 282 * Payload-to-kernel:
 283 *      None.
 284 *
 285 * When the request has been processed, user-space must return the
 286 * dm_ulog_request to the kernel - setting the 'error' field and clearing
 287 * 'data_size' appropriately.
 288 */
 289#define DM_ULOG_SET_REGION_SYNC       13
 290
 291/*
 292 * DM_ULOG_GET_SYNC_COUNT corresponds to (found in dm-dirty-log.h):
 293 * region_t (*get_sync_count)(struct dm_dirty_log *log);
 294 *
 295 * Payload-to-userspace:
 296 *      None.
 297 * Payload-to-kernel:
 298 *      uint64_t - the number of in-sync regions
 299 *
 300 * No incoming payload.  Kernel-bound payload contains the number of
 301 * regions that are in-sync (in a size_t).
 302 *
 303 * When the request has been processed, user-space must return the
 304 * dm_ulog_request to the kernel - setting the 'error' field and
 305 * 'data_size' appropriately.
 306 */
 307#define DM_ULOG_GET_SYNC_COUNT        14
 308
 309/*
 310 * DM_ULOG_STATUS_INFO corresponds to (found in dm-dirty-log.h):
 311 * int (*status)(struct dm_dirty_log *log, STATUSTYPE_INFO,
 312 *               char *result, unsigned maxlen);
 313 *
 314 * Payload-to-userspace:
 315 *      None.
 316 * Payload-to-kernel:
 317 *      Character string containing STATUSTYPE_INFO
 318 *
 319 * When the request has been processed, user-space must return the
 320 * dm_ulog_request to the kernel - setting the 'error' field and
 321 * 'data_size' appropriately.
 322 */
 323#define DM_ULOG_STATUS_INFO           15
 324
 325/*
 326 * DM_ULOG_STATUS_TABLE corresponds to (found in dm-dirty-log.h):
 327 * int (*status)(struct dm_dirty_log *log, STATUSTYPE_TABLE,
 328 *               char *result, unsigned maxlen);
 329 *
 330 * Payload-to-userspace:
 331 *      None.
 332 * Payload-to-kernel:
 333 *      Character string containing STATUSTYPE_TABLE
 334 *
 335 * When the request has been processed, user-space must return the
 336 * dm_ulog_request to the kernel - setting the 'error' field and
 337 * 'data_size' appropriately.
 338 */
 339#define DM_ULOG_STATUS_TABLE          16
 340
 341/*
 342 * DM_ULOG_IS_REMOTE_RECOVERING corresponds to (found in dm-dirty-log.h):
 343 * int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);
 344 *
 345 * Payload-to-userspace:
 346 *      uint64_t - region to determine recovery status on
 347 * Payload-to-kernel:
 348 *      {
 349 *              int64_t is_recovering;  -- 0 if no, 1 if yes
 350 *              uint64_t in_sync_hint;  -- lowest region still needing resync
 351 *      }
 352 *
 353 * When the request has been processed, user-space must return the
 354 * dm_ulog_request to the kernel - setting the 'error' field and
 355 * 'data_size' appropriately.
 356 */
 357#define DM_ULOG_IS_REMOTE_RECOVERING  17
 358
 359/*
 360 * (DM_ULOG_REQUEST_MASK & request_type) to get the request type
 361 *
 362 * Payload-to-userspace:
 363 *      A single string containing all the argv arguments separated by ' 's
 364 * Payload-to-kernel:
 365 *      None.  ('data_size' in the dm_ulog_request struct should be 0.)
 366 *
 367 * We are reserving 8 bits of the 32-bit 'request_type' field for the
 368 * various request types above.  The remaining 24-bits are currently
 369 * set to zero and are reserved for future use and compatibility concerns.
 370 *
 371 * User-space should always use DM_ULOG_REQUEST_TYPE to acquire the
 372 * request type from the 'request_type' field to maintain forward compatibility.
 373 */
 374#define DM_ULOG_REQUEST_MASK 0xFF
 375#define DM_ULOG_REQUEST_TYPE(request_type) \
 376        (DM_ULOG_REQUEST_MASK & (request_type))
 377
 378/*
 379 * DM_ULOG_REQUEST_VERSION is incremented when there is a
 380 * change to the way information is passed between kernel
 381 * and userspace.  This could be a structure change of
 382 * dm_ulog_request or a change in the way requests are
 383 * issued/handled.  Changes are outlined here:
 384 *      version 1:  Initial implementation
 385 *      version 2:  DM_ULOG_CTR allowed to return a string containing a
 386 *                  device name that is to be registered with DM via
 387 *                  'dm_get_device'.
 388 */
 389#define DM_ULOG_REQUEST_VERSION 2
 390
 391struct dm_ulog_request {
 392        /*
 393         * The local unique identifier (luid) and the universally unique
 394         * identifier (uuid) are used to tie a request to a specific
 395         * mirror log.  A single machine log could probably make due with
 396         * just the 'luid', but a cluster-aware log must use the 'uuid' and
 397         * the 'luid'.  The uuid is what is required for node to node
 398         * communication concerning a particular log, but the 'luid' helps
 399         * differentiate between logs that are being swapped and have the
 400         * same 'uuid'.  (Think "live" and "inactive" device-mapper tables.)
 401         */
 402        uint64_t luid;
 403        char uuid[DM_UUID_LEN];
 404        char padding[3];        /* Padding because DM_UUID_LEN = 129 */
 405
 406        uint32_t version;       /* See DM_ULOG_REQUEST_VERSION */
 407        int32_t error;          /* Used to report back processing errors */
 408
 409        uint32_t seq;           /* Sequence number for request */
 410        uint32_t request_type;  /* DM_ULOG_* defined above */
 411        uint32_t data_size;     /* How much data (not including this struct) */
 412
 413        char data[0];
 414};
 415
 416#endif /* __DM_LOG_USERSPACE_H__ */
 417
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