include/uapi/linux/dm-log-userspace.h

   1 /* SPDX-License-Identifier: LGPL-2.0+ WITH Linux-syscall-note */
   2 /*
   3  * Copyright (C) 2006-2009 Red Hat, Inc.
   4  *
   5  * This file is released under the LGPL.
   6  */
   7
   8 #ifndef __DM_LOG_USERSPACE_H__
   9 #define __DM_LOG_USERSPACE_H__
  10
  11 #include <linux/types.h>
  12 #include <linux/dm-ioctl.h> /* For DM_UUID_LEN */
  13
  14 /*
  15  * The device-mapper userspace log module consists of a kernel component and
  16  * a user-space component.  The kernel component implements the API defined
  17  * in dm-dirty-log.h.  Its purpose is simply to pass the parameters and
  18  * return values of those API functions between kernel and user-space.
  19  *
  20  * Below are defined the 'request_types' - DM_ULOG_CTR, DM_ULOG_DTR, etc.
  21  * These request types represent the different functions in the device-mapper
  22  * dirty log API.  Each of these is described in more detail below.
  23  *
  24  * The user-space program must listen for requests from the kernel (representing
  25  * the various API functions) and process them.
  26  *
  27  * User-space begins by setting up the communication link (error checking
  28  * removed for clarity):
  29  *      fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
  30  *      addr.nl_family = AF_NETLINK;
  31  *      addr.nl_groups = CN_IDX_DM;
  32  *      addr.nl_pid = 0;
  33  *      r = bind(fd, (struct sockaddr *) &addr, sizeof(addr));
  34  *      opt = addr.nl_groups;
  35  *      setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &opt, sizeof(opt));
  36  *
  37  * User-space will then wait to receive requests form the kernel, which it
  38  * will process as described below.  The requests are received in the form,
  39  * ((struct dm_ulog_request) + (additional data)).  Depending on the request
  40  * type, there may or may not be 'additional data'.  In the descriptions below,
  41  * you will see 'Payload-to-userspace' and 'Payload-to-kernel'.  The
  42  * 'Payload-to-userspace' is what the kernel sends in 'additional data' as
  43  * necessary parameters to complete the request.  The 'Payload-to-kernel' is
  44  * the 'additional data' returned to the kernel that contains the necessary
  45  * results of the request.  The 'data_size' field in the dm_ulog_request
  46  * structure denotes the availability and amount of payload data.
  47  */
  48
  49 /*
  50  * DM_ULOG_CTR corresponds to (found in dm-dirty-log.h):
  51  * int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
  52  *            unsigned argc, char **argv);
  53  *
  54  * Payload-to-userspace:
  55  *      A single string containing all the argv arguments separated by ' 's
  56  * Payload-to-kernel:
  57  *      A NUL-terminated string that is the name of the device that is used
  58  *      as the backing store for the log data.  'dm_get_device' will be called
  59  *      on this device.  ('dm_put_device' will be called on this device
  60  *      automatically after calling DM_ULOG_DTR.)  If there is no device needed
  61  *      for log data, 'data_size' in the dm_ulog_request struct should be 0.
  62  *
  63  * The UUID contained in the dm_ulog_request structure is the reference that
  64  * will be used by all request types to a specific log.  The constructor must
  65  * record this association with the instance created.
  66  *
  67  * When the request has been processed, user-space must return the
  68  * dm_ulog_request to the kernel - setting the 'error' field, filling the
  69  * data field with the log device if necessary, and setting 'data_size'
  70  * appropriately.
  71  */
  72 #define DM_ULOG_CTR                    1
  73
  74 /*
  75  * DM_ULOG_DTR corresponds to (found in dm-dirty-log.h):
  76  * void (*dtr)(struct dm_dirty_log *log);
  77  *
  78  * Payload-to-userspace:
  79  *      A single string containing all the argv arguments separated by ' 's
  80  * Payload-to-kernel:
  81  *      None.  ('data_size' in the dm_ulog_request struct should be 0.)
  82  *
  83  * The UUID contained in the dm_ulog_request structure is all that is
  84  * necessary to identify the log instance being destroyed.  There is no
  85  * payload data.
  86  *
  87  * When the request has been processed, user-space must return the
  88  * dm_ulog_request to the kernel - setting the 'error' field and clearing
  89  * 'data_size' appropriately.
  90  */
  91 #define DM_ULOG_DTR                    2
  92
  93 /*
  94  * DM_ULOG_PRESUSPEND corresponds to (found in dm-dirty-log.h):
  95  * int (*presuspend)(struct dm_dirty_log *log);
  96  *
  97  * Payload-to-userspace:
  98  *      None.
  99  * Payload-to-kernel:
 100  *      None.
 101  *
 102  * The UUID contained in the dm_ulog_request structure is all that is
 103  * necessary to identify the log instance being presuspended.  There is no
 104  * payload data.
 105  *
 106  * When the request has been processed, user-space must return the
 107  * dm_ulog_request to the kernel - setting the 'error' field and
 108  * 'data_size' appropriately.
 109  */
 110 #define DM_ULOG_PRESUSPEND             3
 111
 112 /*
 113  * DM_ULOG_POSTSUSPEND corresponds to (found in dm-dirty-log.h):
 114  * int (*postsuspend)(struct dm_dirty_log *log);
 115  *
 116  * Payload-to-userspace:
 117  *      None.
 118  * Payload-to-kernel:
 119  *      None.
 120  *
 121  * The UUID contained in the dm_ulog_request structure is all that is
 122  * necessary to identify the log instance being postsuspended.  There is no
 123  * payload data.
 124  *
 125  * When the request has been processed, user-space must return the
 126  * dm_ulog_request to the kernel - setting the 'error' field and
 127  * 'data_size' appropriately.
 128  */
 129 #define DM_ULOG_POSTSUSPEND            4
 130
 131 /*
 132  * DM_ULOG_RESUME corresponds to (found in dm-dirty-log.h):
 133  * int (*resume)(struct dm_dirty_log *log);
 134  *
 135  * Payload-to-userspace:
 136  *      None.
 137  * Payload-to-kernel:
 138  *      None.
 139  *
 140  * The UUID contained in the dm_ulog_request structure is all that is
 141  * necessary to identify the log instance being resumed.  There is no
 142  * payload data.
 143  *
 144  * When the request has been processed, user-space must return the
 145  * dm_ulog_request to the kernel - setting the 'error' field and
 146  * 'data_size' appropriately.
 147  */
 148 #define DM_ULOG_RESUME                 5
 149
 150 /*
 151  * DM_ULOG_GET_REGION_SIZE corresponds to (found in dm-dirty-log.h):
 152  * __u32 (*get_region_size)(struct dm_dirty_log *log);
 153  *
 154  * Payload-to-userspace:
 155  *      None.
 156  * Payload-to-kernel:
 157  *      __u64 - contains the region size
 158  *
 159  * The region size is something that was determined at constructor time.
 160  * It is returned in the payload area and 'data_size' is set to
 161  * reflect this.
 162  *
 163  * When the request has been processed, user-space must return the
 164  * dm_ulog_request to the kernel - setting the 'error' field appropriately.
 165  */
 166 #define DM_ULOG_GET_REGION_SIZE        6
 167
 168 /*
 169  * DM_ULOG_IS_CLEAN corresponds to (found in dm-dirty-log.h):
 170  * int (*is_clean)(struct dm_dirty_log *log, region_t region);
 171  *
 172  * Payload-to-userspace:
 173  *      __u64 - the region to get clean status on
 174  * Payload-to-kernel:
 175  *      __s64  - 1 if clean, 0 otherwise
 176  *
 177  * Payload is sizeof(__u64) and contains the region for which the clean
 178  * status is being made.
 179  *
 180  * When the request has been processed, user-space must return the
 181  * dm_ulog_request to the kernel - filling the payload with 0 (not clean) or
 182  * 1 (clean), setting 'data_size' and 'error' appropriately.
 183  */
 184 #define DM_ULOG_IS_CLEAN               7
 185
 186 /*
 187  * DM_ULOG_IN_SYNC corresponds to (found in dm-dirty-log.h):
 188  * int (*in_sync)(struct dm_dirty_log *log, region_t region,
 189  *                int can_block);
 190  *
 191  * Payload-to-userspace:
 192  *      __u64 - the region to get sync status on
 193  * Payload-to-kernel:
 194  *      __s64 - 1 if in-sync, 0 otherwise
 195  *
 196  * Exactly the same as 'is_clean' above, except this time asking "has the
 197  * region been recovered?" vs. "is the region not being modified?"
 198  */
 199 #define DM_ULOG_IN_SYNC                8
 200
 201 /*
 202  * DM_ULOG_FLUSH corresponds to (found in dm-dirty-log.h):
 203  * int (*flush)(struct dm_dirty_log *log);
 204  *
 205  * Payload-to-userspace:
 206  *      If the 'integrated_flush' directive is present in the constructor
 207  *      table, the payload is as same as DM_ULOG_MARK_REGION:
 208  *              __u64 [] - region(s) to mark
 209  *      else
 210  *              None
 211  * Payload-to-kernel:
 212  *      None.
 213  *
 214  * If the 'integrated_flush' option was used during the creation of the
 215  * log, mark region requests are carried as payload in the flush request.
 216  * Piggybacking the mark requests in this way allows for fewer communications
 217  * between kernel and userspace.
 218  *
 219  * When the request has been processed, user-space must return the
 220  * dm_ulog_request to the kernel - setting the 'error' field and clearing
 221  * 'data_size' appropriately.
 222  */
 223 #define DM_ULOG_FLUSH                  9
 224
 225 /*
 226  * DM_ULOG_MARK_REGION corresponds to (found in dm-dirty-log.h):
 227  * void (*mark_region)(struct dm_dirty_log *log, region_t region);
 228  *
 229  * Payload-to-userspace:
 230  *      __u64 [] - region(s) to mark
 231  * Payload-to-kernel:
 232  *      None.
 233  *
 234  * Incoming payload contains the one or more regions to mark dirty.
 235  * The number of regions contained in the payload can be determined from
 236  * 'data_size/sizeof(__u64)'.
 237  *
 238  * When the request has been processed, user-space must return the
 239  * dm_ulog_request to the kernel - setting the 'error' field and clearing
 240  * 'data_size' appropriately.
 241  */
 242 #define DM_ULOG_MARK_REGION           10
 243
 244 /*
 245  * DM_ULOG_CLEAR_REGION corresponds to (found in dm-dirty-log.h):
 246  * void (*clear_region)(struct dm_dirty_log *log, region_t region);
 247  *
 248  * Payload-to-userspace:
 249  *      __u64 [] - region(s) to clear
 250  * Payload-to-kernel:
 251  *      None.
 252  *
 253  * Incoming payload contains the one or more regions to mark clean.
 254  * The number of regions contained in the payload can be determined from
 255  * 'data_size/sizeof(__u64)'.
 256  *
 257  * When the request has been processed, user-space must return the
 258  * dm_ulog_request to the kernel - setting the 'error' field and clearing
 259  * 'data_size' appropriately.
 260  */
 261 #define DM_ULOG_CLEAR_REGION          11
 262
 263 /*
 264  * DM_ULOG_GET_RESYNC_WORK corresponds to (found in dm-dirty-log.h):
 265  * int (*get_resync_work)(struct dm_dirty_log *log, region_t *region);
 266  *
 267  * Payload-to-userspace:
 268  *      None.
 269  * Payload-to-kernel:
 270  *      {
 271  *              __s64 i; -- 1 if recovery necessary, 0 otherwise
 272  *              __u64 r; -- The region to recover if i=1
 273  *      }
 274  * 'data_size' should be set appropriately.
 275  *
 276  * When the request has been processed, user-space must return the
 277  * dm_ulog_request to the kernel - setting the 'error' field appropriately.
 278  */
 279 #define DM_ULOG_GET_RESYNC_WORK       12
 280
 281 /*
 282  * DM_ULOG_SET_REGION_SYNC corresponds to (found in dm-dirty-log.h):
 283  * void (*set_region_sync)(struct dm_dirty_log *log,
 284  *                         region_t region, int in_sync);
 285  *
 286  * Payload-to-userspace:
 287  *      {
 288  *              __u64 - region to set sync state on
 289  *              __s64  - 0 if not-in-sync, 1 if in-sync
 290  *      }
 291  * Payload-to-kernel:
 292  *      None.
 293  *
 294  * When the request has been processed, user-space must return the
 295  * dm_ulog_request to the kernel - setting the 'error' field and clearing
 296  * 'data_size' appropriately.
 297  */
 298 #define DM_ULOG_SET_REGION_SYNC       13
 299
 300 /*
 301  * DM_ULOG_GET_SYNC_COUNT corresponds to (found in dm-dirty-log.h):
 302  * region_t (*get_sync_count)(struct dm_dirty_log *log);
 303  *
 304  * Payload-to-userspace:
 305  *      None.
 306  * Payload-to-kernel:
 307  *      __u64 - the number of in-sync regions
 308  *
 309  * No incoming payload.  Kernel-bound payload contains the number of
 310  * regions that are in-sync (in a size_t).
 311  *
 312  * When the request has been processed, user-space must return the
 313  * dm_ulog_request to the kernel - setting the 'error' field and
 314  * 'data_size' appropriately.
 315  */
 316 #define DM_ULOG_GET_SYNC_COUNT        14
 317
 318 /*
 319  * DM_ULOG_STATUS_INFO corresponds to (found in dm-dirty-log.h):
 320  * int (*status)(struct dm_dirty_log *log, STATUSTYPE_INFO,
 321  *               char *result, unsigned maxlen);
 322  *
 323  * Payload-to-userspace:
 324  *      None.
 325  * Payload-to-kernel:
 326  *      Character string containing STATUSTYPE_INFO
 327  *
 328  * When the request has been processed, user-space must return the
 329  * dm_ulog_request to the kernel - setting the 'error' field and
 330  * 'data_size' appropriately.
 331  */
 332 #define DM_ULOG_STATUS_INFO           15
 333
 334 /*
 335  * DM_ULOG_STATUS_TABLE corresponds to (found in dm-dirty-log.h):
 336  * int (*status)(struct dm_dirty_log *log, STATUSTYPE_TABLE,
 337  *               char *result, unsigned maxlen);
 338  *
 339  * Payload-to-userspace:
 340  *      None.
 341  * Payload-to-kernel:
 342  *      Character string containing STATUSTYPE_TABLE
 343  *
 344  * When the request has been processed, user-space must return the
 345  * dm_ulog_request to the kernel - setting the 'error' field and
 346  * 'data_size' appropriately.
 347  */
 348 #define DM_ULOG_STATUS_TABLE          16
 349
 350 /*
 351  * DM_ULOG_IS_REMOTE_RECOVERING corresponds to (found in dm-dirty-log.h):
 352  * int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);
 353  *
 354  * Payload-to-userspace:
 355  *      __u64 - region to determine recovery status on
 356  * Payload-to-kernel:
 357  *      {
 358  *              __s64 is_recovering;  -- 0 if no, 1 if yes
 359  *              __u64 in_sync_hint;  -- lowest region still needing resync
 360  *      }
 361  *
 362  * When the request has been processed, user-space must return the
 363  * dm_ulog_request to the kernel - setting the 'error' field and
 364  * 'data_size' appropriately.
 365  */
 366 #define DM_ULOG_IS_REMOTE_RECOVERING  17
 367
 368 /*
 369  * (DM_ULOG_REQUEST_MASK & request_type) to get the request type
 370  *
 371  * Payload-to-userspace:
 372  *      A single string containing all the argv arguments separated by ' 's
 373  * Payload-to-kernel:
 374  *      None.  ('data_size' in the dm_ulog_request struct should be 0.)
 375  *
 376  * We are reserving 8 bits of the 32-bit 'request_type' field for the
 377  * various request types above.  The remaining 24-bits are currently
 378  * set to zero and are reserved for future use and compatibility concerns.
 379  *
 380  * User-space should always use DM_ULOG_REQUEST_TYPE to acquire the
 381  * request type from the 'request_type' field to maintain forward compatibility.
 382  */
 383 #define DM_ULOG_REQUEST_MASK 0xFF
 384 #define DM_ULOG_REQUEST_TYPE(request_type) \
 385         (DM_ULOG_REQUEST_MASK & (request_type))
 386
 387 /*
 388  * DM_ULOG_REQUEST_VERSION is incremented when there is a
 389  * change to the way information is passed between kernel
 390  * and userspace.  This could be a structure change of
 391  * dm_ulog_request or a change in the way requests are
 392  * issued/handled.  Changes are outlined here:
 393  *      version 1:  Initial implementation
 394  *      version 2:  DM_ULOG_CTR allowed to return a string containing a
 395  *                  device name that is to be registered with DM via
 396  *                  'dm_get_device'.
 397  *      version 3:  DM_ULOG_FLUSH is capable of carrying payload for marking
 398  *                  regions.  This "integrated flush" reduces the number of
 399  *                  requests between the kernel and userspace by effectively
 400  *                  merging 'mark' and 'flush' requests.  A constructor table
 401  *                  argument ('integrated_flush') is required to turn this
 402  *                  feature on, so it is backwards compatible with older
 403  *                  userspace versions.
 404  */
 405 #define DM_ULOG_REQUEST_VERSION 3
 406
 407 struct dm_ulog_request {
 408         /*
 409          * The local unique identifier (luid) and the universally unique
 410          * identifier (uuid) are used to tie a request to a specific
 411          * mirror log.  A single machine log could probably make due with
 412          * just the 'luid', but a cluster-aware log must use the 'uuid' and
 413          * the 'luid'.  The uuid is what is required for node to node
 414          * communication concerning a particular log, but the 'luid' helps
 415          * differentiate between logs that are being swapped and have the
 416          * same 'uuid'.  (Think "live" and "inactive" device-mapper tables.)
 417          */
 418         __u64 luid;
 419         char uuid[DM_UUID_LEN];
 420         char padding[3];        /* Padding because DM_UUID_LEN = 129 */
 421
 422         __u32 version;       /* See DM_ULOG_REQUEST_VERSION */
 423         __s32 error;          /* Used to report back processing errors */
 424
 425         __u32 seq;           /* Sequence number for request */
 426         __u32 request_type;  /* DM_ULOG_* defined above */
 427         __u32 data_size;     /* How much data (not including this struct) */
 428
 429         char data[0];
 430 };
 431
 432 #endif /* __DM_LOG_USERSPACE_H__ */