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4db6bfe0 AK |
1 | /* |
2 | * Copyright (C) 2001-2002 Sistina Software (UK) Limited. | |
3 | * Copyright (C) 2006-2008 Red Hat GmbH | |
4 | * | |
5 | * This file is released under the GPL. | |
6 | */ | |
7 | ||
8 | #include "dm-exception-store.h" | |
9 | #include "dm-snap.h" | |
10 | ||
11 | #include <linux/mm.h> | |
12 | #include <linux/pagemap.h> | |
13 | #include <linux/vmalloc.h> | |
14 | #include <linux/slab.h> | |
15 | #include <linux/dm-io.h> | |
16 | ||
17 | #define DM_MSG_PREFIX "persistent snapshot" | |
18 | #define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */ | |
19 | ||
20 | /*----------------------------------------------------------------- | |
21 | * Persistent snapshots, by persistent we mean that the snapshot | |
22 | * will survive a reboot. | |
23 | *---------------------------------------------------------------*/ | |
24 | ||
25 | /* | |
26 | * We need to store a record of which parts of the origin have | |
27 | * been copied to the snapshot device. The snapshot code | |
28 | * requires that we copy exception chunks to chunk aligned areas | |
29 | * of the COW store. It makes sense therefore, to store the | |
30 | * metadata in chunk size blocks. | |
31 | * | |
32 | * There is no backward or forward compatibility implemented, | |
33 | * snapshots with different disk versions than the kernel will | |
34 | * not be usable. It is expected that "lvcreate" will blank out | |
35 | * the start of a fresh COW device before calling the snapshot | |
36 | * constructor. | |
37 | * | |
38 | * The first chunk of the COW device just contains the header. | |
39 | * After this there is a chunk filled with exception metadata, | |
40 | * followed by as many exception chunks as can fit in the | |
41 | * metadata areas. | |
42 | * | |
43 | * All on disk structures are in little-endian format. The end | |
44 | * of the exceptions info is indicated by an exception with a | |
45 | * new_chunk of 0, which is invalid since it would point to the | |
46 | * header chunk. | |
47 | */ | |
48 | ||
49 | /* | |
50 | * Magic for persistent snapshots: "SnAp" - Feeble isn't it. | |
51 | */ | |
52 | #define SNAP_MAGIC 0x70416e53 | |
53 | ||
54 | /* | |
55 | * The on-disk version of the metadata. | |
56 | */ | |
57 | #define SNAPSHOT_DISK_VERSION 1 | |
58 | ||
59 | struct disk_header { | |
60 | uint32_t magic; | |
61 | ||
62 | /* | |
63 | * Is this snapshot valid. There is no way of recovering | |
64 | * an invalid snapshot. | |
65 | */ | |
66 | uint32_t valid; | |
67 | ||
68 | /* | |
69 | * Simple, incrementing version. no backward | |
70 | * compatibility. | |
71 | */ | |
72 | uint32_t version; | |
73 | ||
74 | /* In sectors */ | |
75 | uint32_t chunk_size; | |
76 | }; | |
77 | ||
78 | struct disk_exception { | |
79 | uint64_t old_chunk; | |
80 | uint64_t new_chunk; | |
81 | }; | |
82 | ||
83 | struct commit_callback { | |
84 | void (*callback)(void *, int success); | |
85 | void *context; | |
86 | }; | |
87 | ||
88 | /* | |
89 | * The top level structure for a persistent exception store. | |
90 | */ | |
91 | struct pstore { | |
92 | struct dm_snapshot *snap; /* up pointer to my snapshot */ | |
93 | int version; | |
94 | int valid; | |
95 | uint32_t exceptions_per_area; | |
96 | ||
97 | /* | |
98 | * Now that we have an asynchronous kcopyd there is no | |
99 | * need for large chunk sizes, so it wont hurt to have a | |
100 | * whole chunks worth of metadata in memory at once. | |
101 | */ | |
102 | void *area; | |
103 | ||
104 | /* | |
105 | * An area of zeros used to clear the next area. | |
106 | */ | |
107 | void *zero_area; | |
108 | ||
109 | /* | |
110 | * Used to keep track of which metadata area the data in | |
111 | * 'chunk' refers to. | |
112 | */ | |
113 | chunk_t current_area; | |
114 | ||
115 | /* | |
116 | * The next free chunk for an exception. | |
117 | */ | |
118 | chunk_t next_free; | |
119 | ||
120 | /* | |
121 | * The index of next free exception in the current | |
122 | * metadata area. | |
123 | */ | |
124 | uint32_t current_committed; | |
125 | ||
126 | atomic_t pending_count; | |
127 | uint32_t callback_count; | |
128 | struct commit_callback *callbacks; | |
129 | struct dm_io_client *io_client; | |
130 | ||
131 | struct workqueue_struct *metadata_wq; | |
132 | }; | |
133 | ||
134 | static unsigned sectors_to_pages(unsigned sectors) | |
135 | { | |
136 | return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9); | |
137 | } | |
138 | ||
139 | static int alloc_area(struct pstore *ps) | |
140 | { | |
141 | int r = -ENOMEM; | |
142 | size_t len; | |
143 | ||
144 | len = ps->snap->chunk_size << SECTOR_SHIFT; | |
145 | ||
146 | /* | |
147 | * Allocate the chunk_size block of memory that will hold | |
148 | * a single metadata area. | |
149 | */ | |
150 | ps->area = vmalloc(len); | |
151 | if (!ps->area) | |
152 | return r; | |
153 | ||
154 | ps->zero_area = vmalloc(len); | |
155 | if (!ps->zero_area) { | |
156 | vfree(ps->area); | |
157 | return r; | |
158 | } | |
159 | memset(ps->zero_area, 0, len); | |
160 | ||
161 | return 0; | |
162 | } | |
163 | ||
164 | static void free_area(struct pstore *ps) | |
165 | { | |
166 | vfree(ps->area); | |
167 | ps->area = NULL; | |
168 | vfree(ps->zero_area); | |
169 | ps->zero_area = NULL; | |
170 | } | |
171 | ||
172 | struct mdata_req { | |
173 | struct dm_io_region *where; | |
174 | struct dm_io_request *io_req; | |
175 | struct work_struct work; | |
176 | int result; | |
177 | }; | |
178 | ||
179 | static void do_metadata(struct work_struct *work) | |
180 | { | |
181 | struct mdata_req *req = container_of(work, struct mdata_req, work); | |
182 | ||
183 | req->result = dm_io(req->io_req, 1, req->where, NULL); | |
184 | } | |
185 | ||
186 | /* | |
187 | * Read or write a chunk aligned and sized block of data from a device. | |
188 | */ | |
189 | static int chunk_io(struct pstore *ps, chunk_t chunk, int rw, int metadata) | |
190 | { | |
191 | struct dm_io_region where = { | |
192 | .bdev = ps->snap->cow->bdev, | |
193 | .sector = ps->snap->chunk_size * chunk, | |
194 | .count = ps->snap->chunk_size, | |
195 | }; | |
196 | struct dm_io_request io_req = { | |
197 | .bi_rw = rw, | |
198 | .mem.type = DM_IO_VMA, | |
199 | .mem.ptr.vma = ps->area, | |
200 | .client = ps->io_client, | |
201 | .notify.fn = NULL, | |
202 | }; | |
203 | struct mdata_req req; | |
204 | ||
205 | if (!metadata) | |
206 | return dm_io(&io_req, 1, &where, NULL); | |
207 | ||
208 | req.where = &where; | |
209 | req.io_req = &io_req; | |
210 | ||
211 | /* | |
212 | * Issue the synchronous I/O from a different thread | |
213 | * to avoid generic_make_request recursion. | |
214 | */ | |
215 | INIT_WORK(&req.work, do_metadata); | |
216 | queue_work(ps->metadata_wq, &req.work); | |
217 | flush_workqueue(ps->metadata_wq); | |
218 | ||
219 | return req.result; | |
220 | } | |
221 | ||
222 | /* | |
223 | * Convert a metadata area index to a chunk index. | |
224 | */ | |
225 | static chunk_t area_location(struct pstore *ps, chunk_t area) | |
226 | { | |
227 | return 1 + ((ps->exceptions_per_area + 1) * area); | |
228 | } | |
229 | ||
230 | /* | |
231 | * Read or write a metadata area. Remembering to skip the first | |
232 | * chunk which holds the header. | |
233 | */ | |
234 | static int area_io(struct pstore *ps, int rw) | |
235 | { | |
236 | int r; | |
237 | chunk_t chunk; | |
238 | ||
239 | chunk = area_location(ps, ps->current_area); | |
240 | ||
241 | r = chunk_io(ps, chunk, rw, 0); | |
242 | if (r) | |
243 | return r; | |
244 | ||
245 | return 0; | |
246 | } | |
247 | ||
248 | static void zero_memory_area(struct pstore *ps) | |
249 | { | |
250 | memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT); | |
251 | } | |
252 | ||
253 | static int zero_disk_area(struct pstore *ps, chunk_t area) | |
254 | { | |
255 | struct dm_io_region where = { | |
256 | .bdev = ps->snap->cow->bdev, | |
257 | .sector = ps->snap->chunk_size * area_location(ps, area), | |
258 | .count = ps->snap->chunk_size, | |
259 | }; | |
260 | struct dm_io_request io_req = { | |
261 | .bi_rw = WRITE, | |
262 | .mem.type = DM_IO_VMA, | |
263 | .mem.ptr.vma = ps->zero_area, | |
264 | .client = ps->io_client, | |
265 | .notify.fn = NULL, | |
266 | }; | |
267 | ||
268 | return dm_io(&io_req, 1, &where, NULL); | |
269 | } | |
270 | ||
271 | static int read_header(struct pstore *ps, int *new_snapshot) | |
272 | { | |
273 | int r; | |
274 | struct disk_header *dh; | |
275 | chunk_t chunk_size; | |
276 | int chunk_size_supplied = 1; | |
277 | ||
278 | /* | |
279 | * Use default chunk size (or hardsect_size, if larger) if none supplied | |
280 | */ | |
281 | if (!ps->snap->chunk_size) { | |
282 | ps->snap->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS, | |
283 | bdev_hardsect_size(ps->snap->cow->bdev) >> 9); | |
284 | ps->snap->chunk_mask = ps->snap->chunk_size - 1; | |
285 | ps->snap->chunk_shift = ffs(ps->snap->chunk_size) - 1; | |
286 | chunk_size_supplied = 0; | |
287 | } | |
288 | ||
289 | ps->io_client = dm_io_client_create(sectors_to_pages(ps->snap-> | |
290 | chunk_size)); | |
291 | if (IS_ERR(ps->io_client)) | |
292 | return PTR_ERR(ps->io_client); | |
293 | ||
294 | r = alloc_area(ps); | |
295 | if (r) | |
296 | return r; | |
297 | ||
298 | r = chunk_io(ps, 0, READ, 1); | |
299 | if (r) | |
300 | goto bad; | |
301 | ||
302 | dh = (struct disk_header *) ps->area; | |
303 | ||
304 | if (le32_to_cpu(dh->magic) == 0) { | |
305 | *new_snapshot = 1; | |
306 | return 0; | |
307 | } | |
308 | ||
309 | if (le32_to_cpu(dh->magic) != SNAP_MAGIC) { | |
310 | DMWARN("Invalid or corrupt snapshot"); | |
311 | r = -ENXIO; | |
312 | goto bad; | |
313 | } | |
314 | ||
315 | *new_snapshot = 0; | |
316 | ps->valid = le32_to_cpu(dh->valid); | |
317 | ps->version = le32_to_cpu(dh->version); | |
318 | chunk_size = le32_to_cpu(dh->chunk_size); | |
319 | ||
320 | if (!chunk_size_supplied || ps->snap->chunk_size == chunk_size) | |
321 | return 0; | |
322 | ||
323 | DMWARN("chunk size %llu in device metadata overrides " | |
324 | "table chunk size of %llu.", | |
325 | (unsigned long long)chunk_size, | |
326 | (unsigned long long)ps->snap->chunk_size); | |
327 | ||
328 | /* We had a bogus chunk_size. Fix stuff up. */ | |
329 | free_area(ps); | |
330 | ||
331 | ps->snap->chunk_size = chunk_size; | |
332 | ps->snap->chunk_mask = chunk_size - 1; | |
333 | ps->snap->chunk_shift = ffs(chunk_size) - 1; | |
334 | ||
335 | r = dm_io_client_resize(sectors_to_pages(ps->snap->chunk_size), | |
336 | ps->io_client); | |
337 | if (r) | |
338 | return r; | |
339 | ||
340 | r = alloc_area(ps); | |
341 | return r; | |
342 | ||
343 | bad: | |
344 | free_area(ps); | |
345 | return r; | |
346 | } | |
347 | ||
348 | static int write_header(struct pstore *ps) | |
349 | { | |
350 | struct disk_header *dh; | |
351 | ||
352 | memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT); | |
353 | ||
354 | dh = (struct disk_header *) ps->area; | |
355 | dh->magic = cpu_to_le32(SNAP_MAGIC); | |
356 | dh->valid = cpu_to_le32(ps->valid); | |
357 | dh->version = cpu_to_le32(ps->version); | |
358 | dh->chunk_size = cpu_to_le32(ps->snap->chunk_size); | |
359 | ||
360 | return chunk_io(ps, 0, WRITE, 1); | |
361 | } | |
362 | ||
363 | /* | |
364 | * Access functions for the disk exceptions, these do the endian conversions. | |
365 | */ | |
366 | static struct disk_exception *get_exception(struct pstore *ps, uint32_t index) | |
367 | { | |
368 | BUG_ON(index >= ps->exceptions_per_area); | |
369 | ||
370 | return ((struct disk_exception *) ps->area) + index; | |
371 | } | |
372 | ||
373 | static void read_exception(struct pstore *ps, | |
374 | uint32_t index, struct disk_exception *result) | |
375 | { | |
376 | struct disk_exception *e = get_exception(ps, index); | |
377 | ||
378 | /* copy it */ | |
379 | result->old_chunk = le64_to_cpu(e->old_chunk); | |
380 | result->new_chunk = le64_to_cpu(e->new_chunk); | |
381 | } | |
382 | ||
383 | static void write_exception(struct pstore *ps, | |
384 | uint32_t index, struct disk_exception *de) | |
385 | { | |
386 | struct disk_exception *e = get_exception(ps, index); | |
387 | ||
388 | /* copy it */ | |
389 | e->old_chunk = cpu_to_le64(de->old_chunk); | |
390 | e->new_chunk = cpu_to_le64(de->new_chunk); | |
391 | } | |
392 | ||
393 | /* | |
394 | * Registers the exceptions that are present in the current area. | |
395 | * 'full' is filled in to indicate if the area has been | |
396 | * filled. | |
397 | */ | |
a159c1ac JB |
398 | static int insert_exceptions(struct pstore *ps, |
399 | int (*callback)(void *callback_context, | |
400 | chunk_t old, chunk_t new), | |
401 | void *callback_context, | |
402 | int *full) | |
4db6bfe0 AK |
403 | { |
404 | int r; | |
405 | unsigned int i; | |
406 | struct disk_exception de; | |
407 | ||
408 | /* presume the area is full */ | |
409 | *full = 1; | |
410 | ||
411 | for (i = 0; i < ps->exceptions_per_area; i++) { | |
412 | read_exception(ps, i, &de); | |
413 | ||
414 | /* | |
415 | * If the new_chunk is pointing at the start of | |
416 | * the COW device, where the first metadata area | |
417 | * is we know that we've hit the end of the | |
418 | * exceptions. Therefore the area is not full. | |
419 | */ | |
420 | if (de.new_chunk == 0LL) { | |
421 | ps->current_committed = i; | |
422 | *full = 0; | |
423 | break; | |
424 | } | |
425 | ||
426 | /* | |
427 | * Keep track of the start of the free chunks. | |
428 | */ | |
429 | if (ps->next_free <= de.new_chunk) | |
430 | ps->next_free = de.new_chunk + 1; | |
431 | ||
432 | /* | |
433 | * Otherwise we add the exception to the snapshot. | |
434 | */ | |
a159c1ac | 435 | r = callback(callback_context, de.old_chunk, de.new_chunk); |
4db6bfe0 AK |
436 | if (r) |
437 | return r; | |
438 | } | |
439 | ||
440 | return 0; | |
441 | } | |
442 | ||
a159c1ac JB |
443 | static int read_exceptions(struct pstore *ps, |
444 | int (*callback)(void *callback_context, chunk_t old, | |
445 | chunk_t new), | |
446 | void *callback_context) | |
4db6bfe0 AK |
447 | { |
448 | int r, full = 1; | |
449 | ||
450 | /* | |
451 | * Keeping reading chunks and inserting exceptions until | |
452 | * we find a partially full area. | |
453 | */ | |
454 | for (ps->current_area = 0; full; ps->current_area++) { | |
455 | r = area_io(ps, READ); | |
456 | if (r) | |
457 | return r; | |
458 | ||
a159c1ac | 459 | r = insert_exceptions(ps, callback, callback_context, &full); |
4db6bfe0 AK |
460 | if (r) |
461 | return r; | |
462 | } | |
463 | ||
464 | ps->current_area--; | |
465 | ||
466 | return 0; | |
467 | } | |
468 | ||
469 | static struct pstore *get_info(struct dm_exception_store *store) | |
470 | { | |
471 | return (struct pstore *) store->context; | |
472 | } | |
473 | ||
474 | static void persistent_fraction_full(struct dm_exception_store *store, | |
475 | sector_t *numerator, sector_t *denominator) | |
476 | { | |
477 | *numerator = get_info(store)->next_free * store->snap->chunk_size; | |
478 | *denominator = get_dev_size(store->snap->cow->bdev); | |
479 | } | |
480 | ||
493df71c | 481 | static void persistent_dtr(struct dm_exception_store *store) |
4db6bfe0 AK |
482 | { |
483 | struct pstore *ps = get_info(store); | |
484 | ||
485 | destroy_workqueue(ps->metadata_wq); | |
486 | dm_io_client_destroy(ps->io_client); | |
487 | vfree(ps->callbacks); | |
488 | free_area(ps); | |
489 | kfree(ps); | |
490 | } | |
491 | ||
a159c1ac JB |
492 | static int persistent_read_metadata(struct dm_exception_store *store, |
493 | int (*callback)(void *callback_context, | |
494 | chunk_t old, chunk_t new), | |
495 | void *callback_context) | |
4db6bfe0 AK |
496 | { |
497 | int r, uninitialized_var(new_snapshot); | |
498 | struct pstore *ps = get_info(store); | |
499 | ||
500 | /* | |
501 | * Read the snapshot header. | |
502 | */ | |
503 | r = read_header(ps, &new_snapshot); | |
504 | if (r) | |
505 | return r; | |
506 | ||
507 | /* | |
508 | * Now we know correct chunk_size, complete the initialisation. | |
509 | */ | |
510 | ps->exceptions_per_area = (ps->snap->chunk_size << SECTOR_SHIFT) / | |
511 | sizeof(struct disk_exception); | |
512 | ps->callbacks = dm_vcalloc(ps->exceptions_per_area, | |
513 | sizeof(*ps->callbacks)); | |
514 | if (!ps->callbacks) | |
515 | return -ENOMEM; | |
516 | ||
517 | /* | |
518 | * Do we need to setup a new snapshot ? | |
519 | */ | |
520 | if (new_snapshot) { | |
521 | r = write_header(ps); | |
522 | if (r) { | |
523 | DMWARN("write_header failed"); | |
524 | return r; | |
525 | } | |
526 | ||
527 | ps->current_area = 0; | |
528 | zero_memory_area(ps); | |
529 | r = zero_disk_area(ps, 0); | |
530 | if (r) { | |
531 | DMWARN("zero_disk_area(0) failed"); | |
532 | return r; | |
533 | } | |
534 | } else { | |
535 | /* | |
536 | * Sanity checks. | |
537 | */ | |
538 | if (ps->version != SNAPSHOT_DISK_VERSION) { | |
539 | DMWARN("unable to handle snapshot disk version %d", | |
540 | ps->version); | |
541 | return -EINVAL; | |
542 | } | |
543 | ||
544 | /* | |
545 | * Metadata are valid, but snapshot is invalidated | |
546 | */ | |
547 | if (!ps->valid) | |
548 | return 1; | |
549 | ||
550 | /* | |
551 | * Read the metadata. | |
552 | */ | |
a159c1ac | 553 | r = read_exceptions(ps, callback, callback_context); |
4db6bfe0 AK |
554 | if (r) |
555 | return r; | |
556 | } | |
557 | ||
558 | return 0; | |
559 | } | |
560 | ||
a159c1ac JB |
561 | static int persistent_prepare_exception(struct dm_exception_store *store, |
562 | struct dm_snap_exception *e) | |
4db6bfe0 AK |
563 | { |
564 | struct pstore *ps = get_info(store); | |
565 | uint32_t stride; | |
566 | chunk_t next_free; | |
567 | sector_t size = get_dev_size(store->snap->cow->bdev); | |
568 | ||
569 | /* Is there enough room ? */ | |
570 | if (size < ((ps->next_free + 1) * store->snap->chunk_size)) | |
571 | return -ENOSPC; | |
572 | ||
573 | e->new_chunk = ps->next_free; | |
574 | ||
575 | /* | |
576 | * Move onto the next free pending, making sure to take | |
577 | * into account the location of the metadata chunks. | |
578 | */ | |
579 | stride = (ps->exceptions_per_area + 1); | |
580 | next_free = ++ps->next_free; | |
581 | if (sector_div(next_free, stride) == 1) | |
582 | ps->next_free++; | |
583 | ||
584 | atomic_inc(&ps->pending_count); | |
585 | return 0; | |
586 | } | |
587 | ||
a159c1ac JB |
588 | static void persistent_commit_exception(struct dm_exception_store *store, |
589 | struct dm_snap_exception *e, | |
590 | void (*callback) (void *, int success), | |
591 | void *callback_context) | |
4db6bfe0 AK |
592 | { |
593 | unsigned int i; | |
594 | struct pstore *ps = get_info(store); | |
595 | struct disk_exception de; | |
596 | struct commit_callback *cb; | |
597 | ||
598 | de.old_chunk = e->old_chunk; | |
599 | de.new_chunk = e->new_chunk; | |
600 | write_exception(ps, ps->current_committed++, &de); | |
601 | ||
602 | /* | |
603 | * Add the callback to the back of the array. This code | |
604 | * is the only place where the callback array is | |
605 | * manipulated, and we know that it will never be called | |
606 | * multiple times concurrently. | |
607 | */ | |
608 | cb = ps->callbacks + ps->callback_count++; | |
609 | cb->callback = callback; | |
610 | cb->context = callback_context; | |
611 | ||
612 | /* | |
613 | * If there are exceptions in flight and we have not yet | |
614 | * filled this metadata area there's nothing more to do. | |
615 | */ | |
616 | if (!atomic_dec_and_test(&ps->pending_count) && | |
617 | (ps->current_committed != ps->exceptions_per_area)) | |
618 | return; | |
619 | ||
620 | /* | |
621 | * If we completely filled the current area, then wipe the next one. | |
622 | */ | |
623 | if ((ps->current_committed == ps->exceptions_per_area) && | |
624 | zero_disk_area(ps, ps->current_area + 1)) | |
625 | ps->valid = 0; | |
626 | ||
627 | /* | |
628 | * Commit exceptions to disk. | |
629 | */ | |
630 | if (ps->valid && area_io(ps, WRITE)) | |
631 | ps->valid = 0; | |
632 | ||
633 | /* | |
634 | * Advance to the next area if this one is full. | |
635 | */ | |
636 | if (ps->current_committed == ps->exceptions_per_area) { | |
637 | ps->current_committed = 0; | |
638 | ps->current_area++; | |
639 | zero_memory_area(ps); | |
640 | } | |
641 | ||
642 | for (i = 0; i < ps->callback_count; i++) { | |
643 | cb = ps->callbacks + i; | |
644 | cb->callback(cb->context, ps->valid); | |
645 | } | |
646 | ||
647 | ps->callback_count = 0; | |
648 | } | |
649 | ||
a159c1ac | 650 | static void persistent_drop_snapshot(struct dm_exception_store *store) |
4db6bfe0 AK |
651 | { |
652 | struct pstore *ps = get_info(store); | |
653 | ||
654 | ps->valid = 0; | |
655 | if (write_header(ps)) | |
656 | DMWARN("write header failed"); | |
657 | } | |
658 | ||
493df71c JB |
659 | static int persistent_ctr(struct dm_exception_store *store, |
660 | unsigned argc, char **argv) | |
4db6bfe0 AK |
661 | { |
662 | struct pstore *ps; | |
663 | ||
664 | /* allocate the pstore */ | |
665 | ps = kmalloc(sizeof(*ps), GFP_KERNEL); | |
666 | if (!ps) | |
667 | return -ENOMEM; | |
668 | ||
669 | ps->snap = store->snap; | |
670 | ps->valid = 1; | |
671 | ps->version = SNAPSHOT_DISK_VERSION; | |
672 | ps->area = NULL; | |
673 | ps->next_free = 2; /* skipping the header and first area */ | |
674 | ps->current_committed = 0; | |
675 | ||
676 | ps->callback_count = 0; | |
677 | atomic_set(&ps->pending_count, 0); | |
678 | ps->callbacks = NULL; | |
679 | ||
680 | ps->metadata_wq = create_singlethread_workqueue("ksnaphd"); | |
681 | if (!ps->metadata_wq) { | |
682 | kfree(ps); | |
683 | DMERR("couldn't start header metadata update thread"); | |
684 | return -ENOMEM; | |
685 | } | |
686 | ||
4db6bfe0 AK |
687 | store->context = ps; |
688 | ||
689 | return 0; | |
690 | } | |
691 | ||
493df71c JB |
692 | static int persistent_status(struct dm_exception_store *store, |
693 | status_type_t status, char *result, | |
694 | unsigned int maxlen) | |
695 | { | |
696 | int sz = 0; | |
697 | ||
698 | return sz; | |
699 | } | |
700 | ||
701 | static struct dm_exception_store_type _persistent_type = { | |
702 | .name = "persistent", | |
703 | .module = THIS_MODULE, | |
704 | .ctr = persistent_ctr, | |
705 | .dtr = persistent_dtr, | |
706 | .read_metadata = persistent_read_metadata, | |
707 | .prepare_exception = persistent_prepare_exception, | |
708 | .commit_exception = persistent_commit_exception, | |
709 | .drop_snapshot = persistent_drop_snapshot, | |
710 | .fraction_full = persistent_fraction_full, | |
711 | .status = persistent_status, | |
712 | }; | |
713 | ||
714 | static struct dm_exception_store_type _persistent_compat_type = { | |
715 | .name = "P", | |
716 | .module = THIS_MODULE, | |
717 | .ctr = persistent_ctr, | |
718 | .dtr = persistent_dtr, | |
719 | .read_metadata = persistent_read_metadata, | |
720 | .prepare_exception = persistent_prepare_exception, | |
721 | .commit_exception = persistent_commit_exception, | |
722 | .drop_snapshot = persistent_drop_snapshot, | |
723 | .fraction_full = persistent_fraction_full, | |
724 | .status = persistent_status, | |
725 | }; | |
726 | ||
4db6bfe0 AK |
727 | int dm_persistent_snapshot_init(void) |
728 | { | |
493df71c JB |
729 | int r; |
730 | ||
731 | r = dm_exception_store_type_register(&_persistent_type); | |
732 | if (r) { | |
733 | DMERR("Unable to register persistent exception store type"); | |
734 | return r; | |
735 | } | |
736 | ||
737 | r = dm_exception_store_type_register(&_persistent_compat_type); | |
738 | if (r) { | |
739 | DMERR("Unable to register old-style persistent exception " | |
740 | "store type"); | |
741 | dm_exception_store_type_unregister(&_persistent_type); | |
742 | return r; | |
743 | } | |
744 | ||
745 | return r; | |
4db6bfe0 AK |
746 | } |
747 | ||
748 | void dm_persistent_snapshot_exit(void) | |
749 | { | |
493df71c JB |
750 | dm_exception_store_type_unregister(&_persistent_type); |
751 | dm_exception_store_type_unregister(&_persistent_compat_type); | |
4db6bfe0 | 752 | } |