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  *      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
 391 struct 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__ */