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[];
430 };
431 
432 #endif /* __DM_LOG_USERSPACE_H__ */
433