summaryrefslogtreecommitdiffstats
path: root/include/uapi/linux/dm-log-userspace.h
blob: 5c47a860337654a760de92e0c2d654b8292e0732 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
/* SPDX-License-Identifier: LGPL-2.0+ WITH Linux-syscall-note */
/*
 * Copyright (C) 2006-2009 Red Hat, Inc.
 *
 * This file is released under the LGPL.
 */

#ifndef __DM_LOG_USERSPACE_H__
#define __DM_LOG_USERSPACE_H__

#include <linux/types.h>
#include <linux/dm-ioctl.h> /* For DM_UUID_LEN */

/*
 * The device-mapper userspace log module consists of a kernel component and
 * a user-space component.  The kernel component implements the API defined
 * in dm-dirty-log.h.  Its purpose is simply to pass the parameters and
 * return values of those API functions between kernel and user-space.
 *
 * Below are defined the 'request_types' - DM_ULOG_CTR, DM_ULOG_DTR, etc.
 * These request types represent the different functions in the device-mapper
 * dirty log API.  Each of these is described in more detail below.
 *
 * The user-space program must listen for requests from the kernel (representing
 * the various API functions) and process them.
 *
 * User-space begins by setting up the communication link (error checking
 * removed for clarity):
 *	fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
 *	addr.nl_family = AF_NETLINK;
 *	addr.nl_groups = CN_IDX_DM;
 *	addr.nl_pid = 0;
 *	r = bind(fd, (struct sockaddr *) &addr, sizeof(addr));
 *	opt = addr.nl_groups;
 *	setsockopt(fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &opt, sizeof(opt));
 *
 * User-space will then wait to receive requests form the kernel, which it
 * will process as described below.  The requests are received in the form,
 * ((struct dm_ulog_request) + (additional data)).  Depending on the request
 * type, there may or may not be 'additional data'.  In the descriptions below,
 * you will see 'Payload-to-userspace' and 'Payload-to-kernel'.  The
 * 'Payload-to-userspace' is what the kernel sends in 'additional data' as
 * necessary parameters to complete the request.  The 'Payload-to-kernel' is
 * the 'additional data' returned to the kernel that contains the necessary
 * results of the request.  The 'data_size' field in the dm_ulog_request
 * structure denotes the availability and amount of payload data.
 */

/*
 * DM_ULOG_CTR corresponds to (found in dm-dirty-log.h):
 * int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
 *	      unsigned argc, char **argv);
 *
 * Payload-to-userspace:
 *	A single string containing all the argv arguments separated by ' 's
 * Payload-to-kernel:
 *	A NUL-terminated string that is the name of the device that is used
 *	as the backing store for the log data.  'dm_get_device' will be called
 *	on this device.  ('dm_put_device' will be called on this device
 *	automatically after calling DM_ULOG_DTR.)  If there is no device needed
 *	for log data, 'data_size' in the dm_ulog_request struct should be 0.
 *
 * The UUID contained in the dm_ulog_request structure is the reference that
 * will be used by all request types to a specific log.  The constructor must
 * record this association with the instance created.
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field, filling the
 * data field with the log device if necessary, and setting 'data_size'
 * appropriately.
 */
#define DM_ULOG_CTR                    1

/*
 * DM_ULOG_DTR corresponds to (found in dm-dirty-log.h):
 * void (*dtr)(struct dm_dirty_log *log);
 *
 * Payload-to-userspace:
 *	A single string containing all the argv arguments separated by ' 's
 * Payload-to-kernel:
 *	None.  ('data_size' in the dm_ulog_request struct should be 0.)
 *
 * The UUID contained in the dm_ulog_request structure is all that is
 * necessary to identify the log instance being destroyed.  There is no
 * payload data.
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field and clearing
 * 'data_size' appropriately.
 */
#define DM_ULOG_DTR                    2

/*
 * DM_ULOG_PRESUSPEND corresponds to (found in dm-dirty-log.h):
 * int (*presuspend)(struct dm_dirty_log *log);
 *
 * Payload-to-userspace:
 *	None.
 * Payload-to-kernel:
 *	None.
 *
 * The UUID contained in the dm_ulog_request structure is all that is
 * necessary to identify the log instance being presuspended.  There is no
 * payload data.
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field and
 * 'data_size' appropriately.
 */
#define DM_ULOG_PRESUSPEND             3

/*
 * DM_ULOG_POSTSUSPEND corresponds to (found in dm-dirty-log.h):
 * int (*postsuspend)(struct dm_dirty_log *log);
 *
 * Payload-to-userspace:
 *	None.
 * Payload-to-kernel:
 *	None.
 *
 * The UUID contained in the dm_ulog_request structure is all that is
 * necessary to identify the log instance being postsuspended.  There is no
 * payload data.
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field and
 * 'data_size' appropriately.
 */
#define DM_ULOG_POSTSUSPEND            4

/*
 * DM_ULOG_RESUME corresponds to (found in dm-dirty-log.h):
 * int (*resume)(struct dm_dirty_log *log);
 *
 * Payload-to-userspace:
 *	None.
 * Payload-to-kernel:
 *	None.
 *
 * The UUID contained in the dm_ulog_request structure is all that is
 * necessary to identify the log instance being resumed.  There is no
 * payload data.
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field and
 * 'data_size' appropriately.
 */
#define DM_ULOG_RESUME                 5

/*
 * DM_ULOG_GET_REGION_SIZE corresponds to (found in dm-dirty-log.h):
 * __u32 (*get_region_size)(struct dm_dirty_log *log);
 *
 * Payload-to-userspace:
 *	None.
 * Payload-to-kernel:
 *	__u64 - contains the region size
 *
 * The region size is something that was determined at constructor time.
 * It is returned in the payload area and 'data_size' is set to
 * reflect this.
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field appropriately.
 */
#define DM_ULOG_GET_REGION_SIZE        6

/*
 * DM_ULOG_IS_CLEAN corresponds to (found in dm-dirty-log.h):
 * int (*is_clean)(struct dm_dirty_log *log, region_t region);
 *
 * Payload-to-userspace:
 *	__u64 - the region to get clean status on
 * Payload-to-kernel:
 *	__s64  - 1 if clean, 0 otherwise
 *
 * Payload is sizeof(__u64) and contains the region for which the clean
 * status is being made.
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - filling the payload with 0 (not clean) or
 * 1 (clean), setting 'data_size' and 'error' appropriately.
 */
#define DM_ULOG_IS_CLEAN               7

/*
 * DM_ULOG_IN_SYNC corresponds to (found in dm-dirty-log.h):
 * int (*in_sync)(struct dm_dirty_log *log, region_t region,
 *		  int can_block);
 *
 * Payload-to-userspace:
 *	__u64 - the region to get sync status on
 * Payload-to-kernel:
 *	__s64 - 1 if in-sync, 0 otherwise
 *
 * Exactly the same as 'is_clean' above, except this time asking "has the
 * region been recovered?" vs. "is the region not being modified?"
 */
#define DM_ULOG_IN_SYNC                8

/*
 * DM_ULOG_FLUSH corresponds to (found in dm-dirty-log.h):
 * int (*flush)(struct dm_dirty_log *log);
 *
 * Payload-to-userspace:
 *	If the 'integrated_flush' directive is present in the constructor
 *	table, the payload is as same as DM_ULOG_MARK_REGION:
 *		__u64 [] - region(s) to mark
 *	else
 *		None
 * Payload-to-kernel:
 *	None.
 *
 * If the 'integrated_flush' option was used during the creation of the
 * log, mark region requests are carried as payload in the flush request.
 * Piggybacking the mark requests in this way allows for fewer communications
 * between kernel and userspace.
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field and clearing
 * 'data_size' appropriately.
 */
#define DM_ULOG_FLUSH                  9

/*
 * DM_ULOG_MARK_REGION corresponds to (found in dm-dirty-log.h):
 * void (*mark_region)(struct dm_dirty_log *log, region_t region);
 *
 * Payload-to-userspace:
 *	__u64 [] - region(s) to mark
 * Payload-to-kernel:
 *	None.
 *
 * Incoming payload contains the one or more regions to mark dirty.
 * The number of regions contained in the payload can be determined from
 * 'data_size/sizeof(__u64)'.
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field and clearing
 * 'data_size' appropriately.
 */
#define DM_ULOG_MARK_REGION           10

/*
 * DM_ULOG_CLEAR_REGION corresponds to (found in dm-dirty-log.h):
 * void (*clear_region)(struct dm_dirty_log *log, region_t region);
 *
 * Payload-to-userspace:
 *	__u64 [] - region(s) to clear
 * Payload-to-kernel:
 *	None.
 *
 * Incoming payload contains the one or more regions to mark clean.
 * The number of regions contained in the payload can be determined from
 * 'data_size/sizeof(__u64)'.
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field and clearing
 * 'data_size' appropriately.
 */
#define DM_ULOG_CLEAR_REGION          11

/*
 * DM_ULOG_GET_RESYNC_WORK corresponds to (found in dm-dirty-log.h):
 * int (*get_resync_work)(struct dm_dirty_log *log, region_t *region);
 *
 * Payload-to-userspace:
 *	None.
 * Payload-to-kernel:
 *	{
 *		__s64 i; -- 1 if recovery necessary, 0 otherwise
 *		__u64 r; -- The region to recover if i=1
 *	}
 * 'data_size' should be set appropriately.
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field appropriately.
 */
#define DM_ULOG_GET_RESYNC_WORK       12

/*
 * DM_ULOG_SET_REGION_SYNC corresponds to (found in dm-dirty-log.h):
 * void (*set_region_sync)(struct dm_dirty_log *log,
 *			   region_t region, int in_sync);
 *
 * Payload-to-userspace:
 *	{
 *		__u64 - region to set sync state on
 *		__s64  - 0 if not-in-sync, 1 if in-sync
 *	}
 * Payload-to-kernel:
 *	None.
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field and clearing
 * 'data_size' appropriately.
 */
#define DM_ULOG_SET_REGION_SYNC       13

/*
 * DM_ULOG_GET_SYNC_COUNT corresponds to (found in dm-dirty-log.h):
 * region_t (*get_sync_count)(struct dm_dirty_log *log);
 *
 * Payload-to-userspace:
 *	None.
 * Payload-to-kernel:
 *	__u64 - the number of in-sync regions
 *
 * No incoming payload.  Kernel-bound payload contains the number of
 * regions that are in-sync (in a size_t).
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field and
 * 'data_size' appropriately.
 */
#define DM_ULOG_GET_SYNC_COUNT        14

/*
 * DM_ULOG_STATUS_INFO corresponds to (found in dm-dirty-log.h):
 * int (*status)(struct dm_dirty_log *log, STATUSTYPE_INFO,
 *		 char *result, unsigned maxlen);
 *
 * Payload-to-userspace:
 *	None.
 * Payload-to-kernel:
 *	Character string containing STATUSTYPE_INFO
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field and
 * 'data_size' appropriately.
 */
#define DM_ULOG_STATUS_INFO           15

/*
 * DM_ULOG_STATUS_TABLE corresponds to (found in dm-dirty-log.h):
 * int (*status)(struct dm_dirty_log *log, STATUSTYPE_TABLE,
 *		 char *result, unsigned maxlen);
 *
 * Payload-to-userspace:
 *	None.
 * Payload-to-kernel:
 *	Character string containing STATUSTYPE_TABLE
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field and
 * 'data_size' appropriately.
 */
#define DM_ULOG_STATUS_TABLE          16

/*
 * DM_ULOG_IS_REMOTE_RECOVERING corresponds to (found in dm-dirty-log.h):
 * int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);
 *
 * Payload-to-userspace:
 *	__u64 - region to determine recovery status on
 * Payload-to-kernel:
 *	{
 *		__s64 is_recovering;  -- 0 if no, 1 if yes
 *		__u64 in_sync_hint;  -- lowest region still needing resync
 *	}
 *
 * When the request has been processed, user-space must return the
 * dm_ulog_request to the kernel - setting the 'error' field and
 * 'data_size' appropriately.
 */
#define DM_ULOG_IS_REMOTE_RECOVERING  17

/*
 * (DM_ULOG_REQUEST_MASK & request_type) to get the request type
 *
 * Payload-to-userspace:
 *	A single string containing all the argv arguments separated by ' 's
 * Payload-to-kernel:
 *	None.  ('data_size' in the dm_ulog_request struct should be 0.)
 *
 * We are reserving 8 bits of the 32-bit 'request_type' field for the
 * various request types above.  The remaining 24-bits are currently
 * set to zero and are reserved for future use and compatibility concerns.
 *
 * User-space should always use DM_ULOG_REQUEST_TYPE to acquire the
 * request type from the 'request_type' field to maintain forward compatibility.
 */
#define DM_ULOG_REQUEST_MASK 0xFF
#define DM_ULOG_REQUEST_TYPE(request_type) \
	(DM_ULOG_REQUEST_MASK & (request_type))

/*
 * DM_ULOG_REQUEST_VERSION is incremented when there is a
 * change to the way information is passed between kernel
 * and userspace.  This could be a structure change of
 * dm_ulog_request or a change in the way requests are
 * issued/handled.  Changes are outlined here:
 *	version 1:  Initial implementation
 *	version 2:  DM_ULOG_CTR allowed to return a string containing a
 *	            device name that is to be registered with DM via
 *	            'dm_get_device'.
 *	version 3:  DM_ULOG_FLUSH is capable of carrying payload for marking
 *		    regions.  This "integrated flush" reduces the number of
 *		    requests between the kernel and userspace by effectively
 *		    merging 'mark' and 'flush' requests.  A constructor table
 *		    argument ('integrated_flush') is required to turn this
 *		    feature on, so it is backwards compatible with older
 *		    userspace versions.
 */
#define DM_ULOG_REQUEST_VERSION 3

struct dm_ulog_request {
	/*
	 * The local unique identifier (luid) and the universally unique
	 * identifier (uuid) are used to tie a request to a specific
	 * mirror log.  A single machine log could probably make due with
	 * just the 'luid', but a cluster-aware log must use the 'uuid' and
	 * the 'luid'.  The uuid is what is required for node to node
	 * communication concerning a particular log, but the 'luid' helps
	 * differentiate between logs that are being swapped and have the
	 * same 'uuid'.  (Think "live" and "inactive" device-mapper tables.)
	 */
	__u64 luid;
	char uuid[DM_UUID_LEN];
	char padding[3];        /* Padding because DM_UUID_LEN = 129 */

	__u32 version;       /* See DM_ULOG_REQUEST_VERSION */
	__s32 error;          /* Used to report back processing errors */

	__u32 seq;           /* Sequence number for request */
	__u32 request_type;  /* DM_ULOG_* defined above */
	__u32 data_size;     /* How much data (not including this struct) */

	char data[0];
};

#endif /* __DM_LOG_USERSPACE_H__ */