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dm-log-userspace.h
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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 
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  */
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__ */