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__ */
409