include/linux/dm-log-userspace.h

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