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 *	If the 'integrated_flush' directive is present in the constructor
205 *	table, the payload is as same as DM_ULOG_MARK_REGION:
206 *		uint64_t [] - region(s) to mark
207 *	else
208 *		None
209 * Payload-to-kernel:
210 *	None.
211 *
212 * If the 'integrated_flush' option was used during the creation of the
213 * log, mark region requests are carried as payload in the flush request.
214 * Piggybacking the mark requests in this way allows for fewer communications
215 * between kernel and userspace.
216 *
217 * When the request has been processed, user-space must return the
218 * dm_ulog_request to the kernel - setting the 'error' field and clearing
219 * 'data_size' appropriately.
220 */
221#define DM_ULOG_FLUSH                  9
222
223/*
224 * DM_ULOG_MARK_REGION corresponds to (found in dm-dirty-log.h):
225 * void (*mark_region)(struct dm_dirty_log *log, region_t region);
226 *
227 * Payload-to-userspace:
228 *	uint64_t [] - region(s) to mark
229 * Payload-to-kernel:
230 *	None.
231 *
232 * Incoming payload contains the one or more regions to mark dirty.
233 * The number of regions contained in the payload can be determined from
234 * 'data_size/sizeof(uint64_t)'.
235 *
236 * When the request has been processed, user-space must return the
237 * dm_ulog_request to the kernel - setting the 'error' field and clearing
238 * 'data_size' appropriately.
239 */
240#define DM_ULOG_MARK_REGION           10
241
242/*
243 * DM_ULOG_CLEAR_REGION corresponds to (found in dm-dirty-log.h):
244 * void (*clear_region)(struct dm_dirty_log *log, region_t region);
245 *
246 * Payload-to-userspace:
247 *	uint64_t [] - region(s) to clear
248 * Payload-to-kernel:
249 *	None.
250 *
251 * Incoming payload contains the one or more regions to mark clean.
252 * The number of regions contained in the payload can be determined from
253 * 'data_size/sizeof(uint64_t)'.
254 *
255 * When the request has been processed, user-space must return the
256 * dm_ulog_request to the kernel - setting the 'error' field and clearing
257 * 'data_size' appropriately.
258 */
259#define DM_ULOG_CLEAR_REGION          11
260
261/*
262 * DM_ULOG_GET_RESYNC_WORK corresponds to (found in dm-dirty-log.h):
263 * int (*get_resync_work)(struct dm_dirty_log *log, region_t *region);
264 *
265 * Payload-to-userspace:
266 *	None.
267 * Payload-to-kernel:
268 *	{
269 *		int64_t i; -- 1 if recovery necessary, 0 otherwise
270 *		uint64_t r; -- The region to recover if i=1
271 *	}
272 * 'data_size' should be set appropriately.
273 *
274 * When the request has been processed, user-space must return the
275 * dm_ulog_request to the kernel - setting the 'error' field appropriately.
276 */
277#define DM_ULOG_GET_RESYNC_WORK       12
278
279/*
280 * DM_ULOG_SET_REGION_SYNC corresponds to (found in dm-dirty-log.h):
281 * void (*set_region_sync)(struct dm_dirty_log *log,
282 *			   region_t region, int in_sync);
283 *
284 * Payload-to-userspace:
285 *	{
286 *		uint64_t - region to set sync state on
287 *		int64_t  - 0 if not-in-sync, 1 if in-sync
288 *	}
289 * Payload-to-kernel:
290 *	None.
291 *
292 * When the request has been processed, user-space must return the
293 * dm_ulog_request to the kernel - setting the 'error' field and clearing
294 * 'data_size' appropriately.
295 */
296#define DM_ULOG_SET_REGION_SYNC       13
297
298/*
299 * DM_ULOG_GET_SYNC_COUNT corresponds to (found in dm-dirty-log.h):
300 * region_t (*get_sync_count)(struct dm_dirty_log *log);
301 *
302 * Payload-to-userspace:
303 *	None.
304 * Payload-to-kernel:
305 *	uint64_t - the number of in-sync regions
306 *
307 * No incoming payload.  Kernel-bound payload contains the number of
308 * regions that are in-sync (in a size_t).
309 *
310 * When the request has been processed, user-space must return the
311 * dm_ulog_request to the kernel - setting the 'error' field and
312 * 'data_size' appropriately.
313 */
314#define DM_ULOG_GET_SYNC_COUNT        14
315
316/*
317 * DM_ULOG_STATUS_INFO corresponds to (found in dm-dirty-log.h):
318 * int (*status)(struct dm_dirty_log *log, STATUSTYPE_INFO,
319 *		 char *result, unsigned maxlen);
320 *
321 * Payload-to-userspace:
322 *	None.
323 * Payload-to-kernel:
324 *	Character string containing STATUSTYPE_INFO
325 *
326 * When the request has been processed, user-space must return the
327 * dm_ulog_request to the kernel - setting the 'error' field and
328 * 'data_size' appropriately.
329 */
330#define DM_ULOG_STATUS_INFO           15
331
332/*
333 * DM_ULOG_STATUS_TABLE corresponds to (found in dm-dirty-log.h):
334 * int (*status)(struct dm_dirty_log *log, STATUSTYPE_TABLE,
335 *		 char *result, unsigned maxlen);
336 *
337 * Payload-to-userspace:
338 *	None.
339 * Payload-to-kernel:
340 *	Character string containing STATUSTYPE_TABLE
341 *
342 * When the request has been processed, user-space must return the
343 * dm_ulog_request to the kernel - setting the 'error' field and
344 * 'data_size' appropriately.
345 */
346#define DM_ULOG_STATUS_TABLE          16
347
348/*
349 * DM_ULOG_IS_REMOTE_RECOVERING corresponds to (found in dm-dirty-log.h):
350 * int (*is_remote_recovering)(struct dm_dirty_log *log, region_t region);
351 *
352 * Payload-to-userspace:
353 *	uint64_t - region to determine recovery status on
354 * Payload-to-kernel:
355 *	{
356 *		int64_t is_recovering;  -- 0 if no, 1 if yes
357 *		uint64_t in_sync_hint;  -- lowest region still needing resync
358 *	}
359 *
360 * When the request has been processed, user-space must return the
361 * dm_ulog_request to the kernel - setting the 'error' field and
362 * 'data_size' appropriately.
363 */
364#define DM_ULOG_IS_REMOTE_RECOVERING  17
365
366/*
367 * (DM_ULOG_REQUEST_MASK & request_type) to get the request type
368 *
369 * Payload-to-userspace:
370 *	A single string containing all the argv arguments separated by ' 's
371 * Payload-to-kernel:
372 *	None.  ('data_size' in the dm_ulog_request struct should be 0.)
373 *
374 * We are reserving 8 bits of the 32-bit 'request_type' field for the
375 * various request types above.  The remaining 24-bits are currently
376 * set to zero and are reserved for future use and compatibility concerns.
377 *
378 * User-space should always use DM_ULOG_REQUEST_TYPE to acquire the
379 * request type from the 'request_type' field to maintain forward compatibility.
380 */
381#define DM_ULOG_REQUEST_MASK 0xFF
382#define DM_ULOG_REQUEST_TYPE(request_type) \
383	(DM_ULOG_REQUEST_MASK & (request_type))
384
385/*
386 * DM_ULOG_REQUEST_VERSION is incremented when there is a
387 * change to the way information is passed between kernel
388 * and userspace.  This could be a structure change of
389 * dm_ulog_request or a change in the way requests are
390 * issued/handled.  Changes are outlined here:
391 *	version 1:  Initial implementation
392 *	version 2:  DM_ULOG_CTR allowed to return a string containing a
393 *	            device name that is to be registered with DM via
394 *	            'dm_get_device'.
395 *	version 3:  DM_ULOG_FLUSH is capable of carrying payload for marking
396 *		    regions.  This "integrated flush" reduces the number of
397 *		    requests between the kernel and userspace by effectively
398 *		    merging 'mark' and 'flush' requests.  A constructor table
399 *		    argument ('integrated_flush') is required to turn this
400 *		    feature on, so it is backwards compatible with older
401 *		    userspace versions.
402 */
403#define DM_ULOG_REQUEST_VERSION 3
404
405struct dm_ulog_request {
406	/*
407	 * The local unique identifier (luid) and the universally unique
408	 * identifier (uuid) are used to tie a request to a specific
409	 * mirror log.  A single machine log could probably make due with
410	 * just the 'luid', but a cluster-aware log must use the 'uuid' and
411	 * the 'luid'.  The uuid is what is required for node to node
412	 * communication concerning a particular log, but the 'luid' helps
413	 * differentiate between logs that are being swapped and have the
414	 * same 'uuid'.  (Think "live" and "inactive" device-mapper tables.)
415	 */
416	uint64_t luid;
417	char uuid[DM_UUID_LEN];
418	char padding[3];        /* Padding because DM_UUID_LEN = 129 */
419
420	uint32_t version;       /* See DM_ULOG_REQUEST_VERSION */
421	int32_t error;          /* Used to report back processing errors */
422
423	uint32_t seq;           /* Sequence number for request */
424	uint32_t request_type;  /* DM_ULOG_* defined above */
425	uint32_t data_size;     /* How much data (not including this struct) */
426
427	char data[0];
428};
429
430#endif /* __DM_LOG_USERSPACE_H__ */
431