Commit | Line | Data |
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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" | |
4db6bfe0 AK |
9 | |
10 | #include <linux/mm.h> | |
11 | #include <linux/pagemap.h> | |
12 | #include <linux/vmalloc.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/dm-io.h> | |
15 | ||
16 | #define DM_MSG_PREFIX "persistent snapshot" | |
17 | #define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */ | |
18 | ||
19 | /*----------------------------------------------------------------- | |
20 | * Persistent snapshots, by persistent we mean that the snapshot | |
21 | * will survive a reboot. | |
22 | *---------------------------------------------------------------*/ | |
23 | ||
24 | /* | |
25 | * We need to store a record of which parts of the origin have | |
26 | * been copied to the snapshot device. The snapshot code | |
27 | * requires that we copy exception chunks to chunk aligned areas | |
28 | * of the COW store. It makes sense therefore, to store the | |
29 | * metadata in chunk size blocks. | |
30 | * | |
31 | * There is no backward or forward compatibility implemented, | |
32 | * snapshots with different disk versions than the kernel will | |
33 | * not be usable. It is expected that "lvcreate" will blank out | |
34 | * the start of a fresh COW device before calling the snapshot | |
35 | * constructor. | |
36 | * | |
37 | * The first chunk of the COW device just contains the header. | |
38 | * After this there is a chunk filled with exception metadata, | |
39 | * followed by as many exception chunks as can fit in the | |
40 | * metadata areas. | |
41 | * | |
42 | * All on disk structures are in little-endian format. The end | |
43 | * of the exceptions info is indicated by an exception with a | |
44 | * new_chunk of 0, which is invalid since it would point to the | |
45 | * header chunk. | |
46 | */ | |
47 | ||
48 | /* | |
49 | * Magic for persistent snapshots: "SnAp" - Feeble isn't it. | |
50 | */ | |
51 | #define SNAP_MAGIC 0x70416e53 | |
52 | ||
53 | /* | |
54 | * The on-disk version of the metadata. | |
55 | */ | |
56 | #define SNAPSHOT_DISK_VERSION 1 | |
57 | ||
58 | struct disk_header { | |
59 | uint32_t magic; | |
60 | ||
61 | /* | |
62 | * Is this snapshot valid. There is no way of recovering | |
63 | * an invalid snapshot. | |
64 | */ | |
65 | uint32_t valid; | |
66 | ||
67 | /* | |
68 | * Simple, incrementing version. no backward | |
69 | * compatibility. | |
70 | */ | |
71 | uint32_t version; | |
72 | ||
73 | /* In sectors */ | |
74 | uint32_t chunk_size; | |
75 | }; | |
76 | ||
77 | struct disk_exception { | |
78 | uint64_t old_chunk; | |
79 | uint64_t new_chunk; | |
80 | }; | |
81 | ||
82 | struct commit_callback { | |
83 | void (*callback)(void *, int success); | |
84 | void *context; | |
85 | }; | |
86 | ||
87 | /* | |
88 | * The top level structure for a persistent exception store. | |
89 | */ | |
90 | struct pstore { | |
71fab00a | 91 | struct dm_exception_store *store; |
4db6bfe0 AK |
92 | int version; |
93 | int valid; | |
94 | uint32_t exceptions_per_area; | |
95 | ||
96 | /* | |
97 | * Now that we have an asynchronous kcopyd there is no | |
98 | * need for large chunk sizes, so it wont hurt to have a | |
99 | * whole chunks worth of metadata in memory at once. | |
100 | */ | |
101 | void *area; | |
102 | ||
103 | /* | |
104 | * An area of zeros used to clear the next area. | |
105 | */ | |
106 | void *zero_area; | |
107 | ||
108 | /* | |
109 | * Used to keep track of which metadata area the data in | |
110 | * 'chunk' refers to. | |
111 | */ | |
112 | chunk_t current_area; | |
113 | ||
114 | /* | |
115 | * The next free chunk for an exception. | |
116 | */ | |
117 | chunk_t next_free; | |
118 | ||
119 | /* | |
120 | * The index of next free exception in the current | |
121 | * metadata area. | |
122 | */ | |
123 | uint32_t current_committed; | |
124 | ||
125 | atomic_t pending_count; | |
126 | uint32_t callback_count; | |
127 | struct commit_callback *callbacks; | |
128 | struct dm_io_client *io_client; | |
129 | ||
130 | struct workqueue_struct *metadata_wq; | |
131 | }; | |
132 | ||
133 | static unsigned sectors_to_pages(unsigned sectors) | |
134 | { | |
135 | return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9); | |
136 | } | |
137 | ||
138 | static int alloc_area(struct pstore *ps) | |
139 | { | |
140 | int r = -ENOMEM; | |
141 | size_t len; | |
142 | ||
71fab00a | 143 | len = ps->store->chunk_size << SECTOR_SHIFT; |
4db6bfe0 AK |
144 | |
145 | /* | |
146 | * Allocate the chunk_size block of memory that will hold | |
147 | * a single metadata area. | |
148 | */ | |
149 | ps->area = vmalloc(len); | |
150 | if (!ps->area) | |
151 | return r; | |
152 | ||
153 | ps->zero_area = vmalloc(len); | |
154 | if (!ps->zero_area) { | |
155 | vfree(ps->area); | |
156 | return r; | |
157 | } | |
158 | memset(ps->zero_area, 0, len); | |
159 | ||
160 | return 0; | |
161 | } | |
162 | ||
163 | static void free_area(struct pstore *ps) | |
164 | { | |
a32079ce JB |
165 | if (ps->area) |
166 | vfree(ps->area); | |
4db6bfe0 | 167 | ps->area = NULL; |
a32079ce JB |
168 | |
169 | if (ps->zero_area) | |
170 | vfree(ps->zero_area); | |
4db6bfe0 AK |
171 | ps->zero_area = NULL; |
172 | } | |
173 | ||
174 | struct mdata_req { | |
175 | struct dm_io_region *where; | |
176 | struct dm_io_request *io_req; | |
177 | struct work_struct work; | |
178 | int result; | |
179 | }; | |
180 | ||
181 | static void do_metadata(struct work_struct *work) | |
182 | { | |
183 | struct mdata_req *req = container_of(work, struct mdata_req, work); | |
184 | ||
185 | req->result = dm_io(req->io_req, 1, req->where, NULL); | |
186 | } | |
187 | ||
188 | /* | |
189 | * Read or write a chunk aligned and sized block of data from a device. | |
190 | */ | |
191 | static int chunk_io(struct pstore *ps, chunk_t chunk, int rw, int metadata) | |
192 | { | |
193 | struct dm_io_region where = { | |
71fab00a JB |
194 | .bdev = ps->store->cow->bdev, |
195 | .sector = ps->store->chunk_size * chunk, | |
196 | .count = ps->store->chunk_size, | |
4db6bfe0 AK |
197 | }; |
198 | struct dm_io_request io_req = { | |
199 | .bi_rw = rw, | |
200 | .mem.type = DM_IO_VMA, | |
201 | .mem.ptr.vma = ps->area, | |
202 | .client = ps->io_client, | |
203 | .notify.fn = NULL, | |
204 | }; | |
205 | struct mdata_req req; | |
206 | ||
207 | if (!metadata) | |
208 | return dm_io(&io_req, 1, &where, NULL); | |
209 | ||
210 | req.where = &where; | |
211 | req.io_req = &io_req; | |
212 | ||
213 | /* | |
214 | * Issue the synchronous I/O from a different thread | |
215 | * to avoid generic_make_request recursion. | |
216 | */ | |
217 | INIT_WORK(&req.work, do_metadata); | |
218 | queue_work(ps->metadata_wq, &req.work); | |
219 | flush_workqueue(ps->metadata_wq); | |
220 | ||
221 | return req.result; | |
222 | } | |
223 | ||
224 | /* | |
225 | * Convert a metadata area index to a chunk index. | |
226 | */ | |
227 | static chunk_t area_location(struct pstore *ps, chunk_t area) | |
228 | { | |
229 | return 1 + ((ps->exceptions_per_area + 1) * area); | |
230 | } | |
231 | ||
232 | /* | |
233 | * Read or write a metadata area. Remembering to skip the first | |
234 | * chunk which holds the header. | |
235 | */ | |
236 | static int area_io(struct pstore *ps, int rw) | |
237 | { | |
238 | int r; | |
239 | chunk_t chunk; | |
240 | ||
241 | chunk = area_location(ps, ps->current_area); | |
242 | ||
243 | r = chunk_io(ps, chunk, rw, 0); | |
244 | if (r) | |
245 | return r; | |
246 | ||
247 | return 0; | |
248 | } | |
249 | ||
250 | static void zero_memory_area(struct pstore *ps) | |
251 | { | |
71fab00a | 252 | memset(ps->area, 0, ps->store->chunk_size << SECTOR_SHIFT); |
4db6bfe0 AK |
253 | } |
254 | ||
255 | static int zero_disk_area(struct pstore *ps, chunk_t area) | |
256 | { | |
257 | struct dm_io_region where = { | |
71fab00a JB |
258 | .bdev = ps->store->cow->bdev, |
259 | .sector = ps->store->chunk_size * area_location(ps, area), | |
260 | .count = ps->store->chunk_size, | |
4db6bfe0 AK |
261 | }; |
262 | struct dm_io_request io_req = { | |
263 | .bi_rw = WRITE, | |
264 | .mem.type = DM_IO_VMA, | |
265 | .mem.ptr.vma = ps->zero_area, | |
266 | .client = ps->io_client, | |
267 | .notify.fn = NULL, | |
268 | }; | |
269 | ||
270 | return dm_io(&io_req, 1, &where, NULL); | |
271 | } | |
272 | ||
273 | static int read_header(struct pstore *ps, int *new_snapshot) | |
274 | { | |
275 | int r; | |
276 | struct disk_header *dh; | |
277 | chunk_t chunk_size; | |
278 | int chunk_size_supplied = 1; | |
279 | ||
280 | /* | |
281 | * Use default chunk size (or hardsect_size, if larger) if none supplied | |
282 | */ | |
71fab00a JB |
283 | if (!ps->store->chunk_size) { |
284 | ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS, | |
285 | bdev_hardsect_size(ps->store->cow->bdev) >> 9); | |
286 | ps->store->chunk_mask = ps->store->chunk_size - 1; | |
287 | ps->store->chunk_shift = ffs(ps->store->chunk_size) - 1; | |
4db6bfe0 AK |
288 | chunk_size_supplied = 0; |
289 | } | |
290 | ||
71fab00a JB |
291 | ps->io_client = dm_io_client_create(sectors_to_pages(ps->store-> |
292 | chunk_size)); | |
4db6bfe0 AK |
293 | if (IS_ERR(ps->io_client)) |
294 | return PTR_ERR(ps->io_client); | |
295 | ||
296 | r = alloc_area(ps); | |
297 | if (r) | |
298 | return r; | |
299 | ||
300 | r = chunk_io(ps, 0, READ, 1); | |
301 | if (r) | |
302 | goto bad; | |
303 | ||
304 | dh = (struct disk_header *) ps->area; | |
305 | ||
306 | if (le32_to_cpu(dh->magic) == 0) { | |
307 | *new_snapshot = 1; | |
308 | return 0; | |
309 | } | |
310 | ||
311 | if (le32_to_cpu(dh->magic) != SNAP_MAGIC) { | |
312 | DMWARN("Invalid or corrupt snapshot"); | |
313 | r = -ENXIO; | |
314 | goto bad; | |
315 | } | |
316 | ||
317 | *new_snapshot = 0; | |
318 | ps->valid = le32_to_cpu(dh->valid); | |
319 | ps->version = le32_to_cpu(dh->version); | |
320 | chunk_size = le32_to_cpu(dh->chunk_size); | |
321 | ||
71fab00a | 322 | if (!chunk_size_supplied || ps->store->chunk_size == chunk_size) |
4db6bfe0 AK |
323 | return 0; |
324 | ||
325 | DMWARN("chunk size %llu in device metadata overrides " | |
326 | "table chunk size of %llu.", | |
327 | (unsigned long long)chunk_size, | |
71fab00a | 328 | (unsigned long long)ps->store->chunk_size); |
4db6bfe0 AK |
329 | |
330 | /* We had a bogus chunk_size. Fix stuff up. */ | |
331 | free_area(ps); | |
332 | ||
71fab00a JB |
333 | ps->store->chunk_size = chunk_size; |
334 | ps->store->chunk_mask = chunk_size - 1; | |
335 | ps->store->chunk_shift = ffs(chunk_size) - 1; | |
4db6bfe0 | 336 | |
71fab00a | 337 | r = dm_io_client_resize(sectors_to_pages(ps->store->chunk_size), |
4db6bfe0 AK |
338 | ps->io_client); |
339 | if (r) | |
340 | return r; | |
341 | ||
342 | r = alloc_area(ps); | |
343 | return r; | |
344 | ||
345 | bad: | |
346 | free_area(ps); | |
347 | return r; | |
348 | } | |
349 | ||
350 | static int write_header(struct pstore *ps) | |
351 | { | |
352 | struct disk_header *dh; | |
353 | ||
71fab00a | 354 | memset(ps->area, 0, ps->store->chunk_size << SECTOR_SHIFT); |
4db6bfe0 AK |
355 | |
356 | dh = (struct disk_header *) ps->area; | |
357 | dh->magic = cpu_to_le32(SNAP_MAGIC); | |
358 | dh->valid = cpu_to_le32(ps->valid); | |
359 | dh->version = cpu_to_le32(ps->version); | |
71fab00a | 360 | dh->chunk_size = cpu_to_le32(ps->store->chunk_size); |
4db6bfe0 AK |
361 | |
362 | return chunk_io(ps, 0, WRITE, 1); | |
363 | } | |
364 | ||
365 | /* | |
366 | * Access functions for the disk exceptions, these do the endian conversions. | |
367 | */ | |
368 | static struct disk_exception *get_exception(struct pstore *ps, uint32_t index) | |
369 | { | |
370 | BUG_ON(index >= ps->exceptions_per_area); | |
371 | ||
372 | return ((struct disk_exception *) ps->area) + index; | |
373 | } | |
374 | ||
375 | static void read_exception(struct pstore *ps, | |
376 | uint32_t index, struct disk_exception *result) | |
377 | { | |
378 | struct disk_exception *e = get_exception(ps, index); | |
379 | ||
380 | /* copy it */ | |
381 | result->old_chunk = le64_to_cpu(e->old_chunk); | |
382 | result->new_chunk = le64_to_cpu(e->new_chunk); | |
383 | } | |
384 | ||
385 | static void write_exception(struct pstore *ps, | |
386 | uint32_t index, struct disk_exception *de) | |
387 | { | |
388 | struct disk_exception *e = get_exception(ps, index); | |
389 | ||
390 | /* copy it */ | |
391 | e->old_chunk = cpu_to_le64(de->old_chunk); | |
392 | e->new_chunk = cpu_to_le64(de->new_chunk); | |
393 | } | |
394 | ||
395 | /* | |
396 | * Registers the exceptions that are present in the current area. | |
397 | * 'full' is filled in to indicate if the area has been | |
398 | * filled. | |
399 | */ | |
a159c1ac JB |
400 | static int insert_exceptions(struct pstore *ps, |
401 | int (*callback)(void *callback_context, | |
402 | chunk_t old, chunk_t new), | |
403 | void *callback_context, | |
404 | int *full) | |
4db6bfe0 AK |
405 | { |
406 | int r; | |
407 | unsigned int i; | |
408 | struct disk_exception de; | |
409 | ||
410 | /* presume the area is full */ | |
411 | *full = 1; | |
412 | ||
413 | for (i = 0; i < ps->exceptions_per_area; i++) { | |
414 | read_exception(ps, i, &de); | |
415 | ||
416 | /* | |
417 | * If the new_chunk is pointing at the start of | |
418 | * the COW device, where the first metadata area | |
419 | * is we know that we've hit the end of the | |
420 | * exceptions. Therefore the area is not full. | |
421 | */ | |
422 | if (de.new_chunk == 0LL) { | |
423 | ps->current_committed = i; | |
424 | *full = 0; | |
425 | break; | |
426 | } | |
427 | ||
428 | /* | |
429 | * Keep track of the start of the free chunks. | |
430 | */ | |
431 | if (ps->next_free <= de.new_chunk) | |
432 | ps->next_free = de.new_chunk + 1; | |
433 | ||
434 | /* | |
435 | * Otherwise we add the exception to the snapshot. | |
436 | */ | |
a159c1ac | 437 | r = callback(callback_context, de.old_chunk, de.new_chunk); |
4db6bfe0 AK |
438 | if (r) |
439 | return r; | |
440 | } | |
441 | ||
442 | return 0; | |
443 | } | |
444 | ||
a159c1ac JB |
445 | static int read_exceptions(struct pstore *ps, |
446 | int (*callback)(void *callback_context, chunk_t old, | |
447 | chunk_t new), | |
448 | void *callback_context) | |
4db6bfe0 AK |
449 | { |
450 | int r, full = 1; | |
451 | ||
452 | /* | |
453 | * Keeping reading chunks and inserting exceptions until | |
454 | * we find a partially full area. | |
455 | */ | |
456 | for (ps->current_area = 0; full; ps->current_area++) { | |
457 | r = area_io(ps, READ); | |
458 | if (r) | |
459 | return r; | |
460 | ||
a159c1ac | 461 | r = insert_exceptions(ps, callback, callback_context, &full); |
4db6bfe0 AK |
462 | if (r) |
463 | return r; | |
464 | } | |
465 | ||
466 | ps->current_area--; | |
467 | ||
468 | return 0; | |
469 | } | |
470 | ||
471 | static struct pstore *get_info(struct dm_exception_store *store) | |
472 | { | |
473 | return (struct pstore *) store->context; | |
474 | } | |
475 | ||
476 | static void persistent_fraction_full(struct dm_exception_store *store, | |
477 | sector_t *numerator, sector_t *denominator) | |
478 | { | |
d0216849 | 479 | *numerator = get_info(store)->next_free * store->chunk_size; |
49beb2b8 | 480 | *denominator = get_dev_size(store->cow->bdev); |
4db6bfe0 AK |
481 | } |
482 | ||
493df71c | 483 | static void persistent_dtr(struct dm_exception_store *store) |
4db6bfe0 AK |
484 | { |
485 | struct pstore *ps = get_info(store); | |
486 | ||
487 | destroy_workqueue(ps->metadata_wq); | |
a32079ce JB |
488 | |
489 | /* Created in read_header */ | |
490 | if (ps->io_client) | |
491 | dm_io_client_destroy(ps->io_client); | |
4db6bfe0 | 492 | free_area(ps); |
a32079ce JB |
493 | |
494 | /* Allocated in persistent_read_metadata */ | |
495 | if (ps->callbacks) | |
496 | vfree(ps->callbacks); | |
497 | ||
4db6bfe0 AK |
498 | kfree(ps); |
499 | } | |
500 | ||
a159c1ac JB |
501 | static int persistent_read_metadata(struct dm_exception_store *store, |
502 | int (*callback)(void *callback_context, | |
503 | chunk_t old, chunk_t new), | |
504 | void *callback_context) | |
4db6bfe0 AK |
505 | { |
506 | int r, uninitialized_var(new_snapshot); | |
507 | struct pstore *ps = get_info(store); | |
508 | ||
509 | /* | |
510 | * Read the snapshot header. | |
511 | */ | |
512 | r = read_header(ps, &new_snapshot); | |
513 | if (r) | |
514 | return r; | |
515 | ||
516 | /* | |
517 | * Now we know correct chunk_size, complete the initialisation. | |
518 | */ | |
71fab00a JB |
519 | ps->exceptions_per_area = (ps->store->chunk_size << SECTOR_SHIFT) / |
520 | sizeof(struct disk_exception); | |
4db6bfe0 AK |
521 | ps->callbacks = dm_vcalloc(ps->exceptions_per_area, |
522 | sizeof(*ps->callbacks)); | |
523 | if (!ps->callbacks) | |
524 | return -ENOMEM; | |
525 | ||
526 | /* | |
527 | * Do we need to setup a new snapshot ? | |
528 | */ | |
529 | if (new_snapshot) { | |
530 | r = write_header(ps); | |
531 | if (r) { | |
532 | DMWARN("write_header failed"); | |
533 | return r; | |
534 | } | |
535 | ||
536 | ps->current_area = 0; | |
537 | zero_memory_area(ps); | |
538 | r = zero_disk_area(ps, 0); | |
539 | if (r) { | |
540 | DMWARN("zero_disk_area(0) failed"); | |
541 | return r; | |
542 | } | |
543 | } else { | |
544 | /* | |
545 | * Sanity checks. | |
546 | */ | |
547 | if (ps->version != SNAPSHOT_DISK_VERSION) { | |
548 | DMWARN("unable to handle snapshot disk version %d", | |
549 | ps->version); | |
550 | return -EINVAL; | |
551 | } | |
552 | ||
553 | /* | |
554 | * Metadata are valid, but snapshot is invalidated | |
555 | */ | |
556 | if (!ps->valid) | |
557 | return 1; | |
558 | ||
559 | /* | |
560 | * Read the metadata. | |
561 | */ | |
a159c1ac | 562 | r = read_exceptions(ps, callback, callback_context); |
4db6bfe0 AK |
563 | if (r) |
564 | return r; | |
565 | } | |
566 | ||
567 | return 0; | |
568 | } | |
569 | ||
a159c1ac JB |
570 | static int persistent_prepare_exception(struct dm_exception_store *store, |
571 | struct dm_snap_exception *e) | |
4db6bfe0 AK |
572 | { |
573 | struct pstore *ps = get_info(store); | |
574 | uint32_t stride; | |
575 | chunk_t next_free; | |
49beb2b8 | 576 | sector_t size = get_dev_size(store->cow->bdev); |
4db6bfe0 AK |
577 | |
578 | /* Is there enough room ? */ | |
d0216849 | 579 | if (size < ((ps->next_free + 1) * store->chunk_size)) |
4db6bfe0 AK |
580 | return -ENOSPC; |
581 | ||
582 | e->new_chunk = ps->next_free; | |
583 | ||
584 | /* | |
585 | * Move onto the next free pending, making sure to take | |
586 | * into account the location of the metadata chunks. | |
587 | */ | |
588 | stride = (ps->exceptions_per_area + 1); | |
589 | next_free = ++ps->next_free; | |
590 | if (sector_div(next_free, stride) == 1) | |
591 | ps->next_free++; | |
592 | ||
593 | atomic_inc(&ps->pending_count); | |
594 | return 0; | |
595 | } | |
596 | ||
a159c1ac JB |
597 | static void persistent_commit_exception(struct dm_exception_store *store, |
598 | struct dm_snap_exception *e, | |
599 | void (*callback) (void *, int success), | |
600 | void *callback_context) | |
4db6bfe0 AK |
601 | { |
602 | unsigned int i; | |
603 | struct pstore *ps = get_info(store); | |
604 | struct disk_exception de; | |
605 | struct commit_callback *cb; | |
606 | ||
607 | de.old_chunk = e->old_chunk; | |
608 | de.new_chunk = e->new_chunk; | |
609 | write_exception(ps, ps->current_committed++, &de); | |
610 | ||
611 | /* | |
612 | * Add the callback to the back of the array. This code | |
613 | * is the only place where the callback array is | |
614 | * manipulated, and we know that it will never be called | |
615 | * multiple times concurrently. | |
616 | */ | |
617 | cb = ps->callbacks + ps->callback_count++; | |
618 | cb->callback = callback; | |
619 | cb->context = callback_context; | |
620 | ||
621 | /* | |
622 | * If there are exceptions in flight and we have not yet | |
623 | * filled this metadata area there's nothing more to do. | |
624 | */ | |
625 | if (!atomic_dec_and_test(&ps->pending_count) && | |
626 | (ps->current_committed != ps->exceptions_per_area)) | |
627 | return; | |
628 | ||
629 | /* | |
630 | * If we completely filled the current area, then wipe the next one. | |
631 | */ | |
632 | if ((ps->current_committed == ps->exceptions_per_area) && | |
633 | zero_disk_area(ps, ps->current_area + 1)) | |
634 | ps->valid = 0; | |
635 | ||
636 | /* | |
637 | * Commit exceptions to disk. | |
638 | */ | |
639 | if (ps->valid && area_io(ps, WRITE)) | |
640 | ps->valid = 0; | |
641 | ||
642 | /* | |
643 | * Advance to the next area if this one is full. | |
644 | */ | |
645 | if (ps->current_committed == ps->exceptions_per_area) { | |
646 | ps->current_committed = 0; | |
647 | ps->current_area++; | |
648 | zero_memory_area(ps); | |
649 | } | |
650 | ||
651 | for (i = 0; i < ps->callback_count; i++) { | |
652 | cb = ps->callbacks + i; | |
653 | cb->callback(cb->context, ps->valid); | |
654 | } | |
655 | ||
656 | ps->callback_count = 0; | |
657 | } | |
658 | ||
a159c1ac | 659 | static void persistent_drop_snapshot(struct dm_exception_store *store) |
4db6bfe0 AK |
660 | { |
661 | struct pstore *ps = get_info(store); | |
662 | ||
663 | ps->valid = 0; | |
664 | if (write_header(ps)) | |
665 | DMWARN("write header failed"); | |
666 | } | |
667 | ||
493df71c JB |
668 | static int persistent_ctr(struct dm_exception_store *store, |
669 | unsigned argc, char **argv) | |
4db6bfe0 AK |
670 | { |
671 | struct pstore *ps; | |
672 | ||
673 | /* allocate the pstore */ | |
a32079ce | 674 | ps = kzalloc(sizeof(*ps), GFP_KERNEL); |
4db6bfe0 AK |
675 | if (!ps) |
676 | return -ENOMEM; | |
677 | ||
71fab00a | 678 | ps->store = store; |
4db6bfe0 AK |
679 | ps->valid = 1; |
680 | ps->version = SNAPSHOT_DISK_VERSION; | |
681 | ps->area = NULL; | |
682 | ps->next_free = 2; /* skipping the header and first area */ | |
683 | ps->current_committed = 0; | |
684 | ||
685 | ps->callback_count = 0; | |
686 | atomic_set(&ps->pending_count, 0); | |
687 | ps->callbacks = NULL; | |
688 | ||
689 | ps->metadata_wq = create_singlethread_workqueue("ksnaphd"); | |
690 | if (!ps->metadata_wq) { | |
691 | kfree(ps); | |
692 | DMERR("couldn't start header metadata update thread"); | |
693 | return -ENOMEM; | |
694 | } | |
695 | ||
4db6bfe0 AK |
696 | store->context = ps; |
697 | ||
698 | return 0; | |
699 | } | |
700 | ||
1e302a92 JB |
701 | static unsigned persistent_status(struct dm_exception_store *store, |
702 | status_type_t status, char *result, | |
703 | unsigned maxlen) | |
493df71c | 704 | { |
1e302a92 JB |
705 | unsigned sz = 0; |
706 | ||
707 | switch (status) { | |
708 | case STATUSTYPE_INFO: | |
709 | break; | |
710 | case STATUSTYPE_TABLE: | |
711 | DMEMIT(" %s P %llu", store->cow->name, | |
712 | (unsigned long long)store->chunk_size); | |
713 | } | |
493df71c JB |
714 | |
715 | return sz; | |
716 | } | |
717 | ||
718 | static struct dm_exception_store_type _persistent_type = { | |
719 | .name = "persistent", | |
720 | .module = THIS_MODULE, | |
721 | .ctr = persistent_ctr, | |
722 | .dtr = persistent_dtr, | |
723 | .read_metadata = persistent_read_metadata, | |
724 | .prepare_exception = persistent_prepare_exception, | |
725 | .commit_exception = persistent_commit_exception, | |
726 | .drop_snapshot = persistent_drop_snapshot, | |
727 | .fraction_full = persistent_fraction_full, | |
728 | .status = persistent_status, | |
729 | }; | |
730 | ||
731 | static struct dm_exception_store_type _persistent_compat_type = { | |
732 | .name = "P", | |
733 | .module = THIS_MODULE, | |
734 | .ctr = persistent_ctr, | |
735 | .dtr = persistent_dtr, | |
736 | .read_metadata = persistent_read_metadata, | |
737 | .prepare_exception = persistent_prepare_exception, | |
738 | .commit_exception = persistent_commit_exception, | |
739 | .drop_snapshot = persistent_drop_snapshot, | |
740 | .fraction_full = persistent_fraction_full, | |
741 | .status = persistent_status, | |
742 | }; | |
743 | ||
4db6bfe0 AK |
744 | int dm_persistent_snapshot_init(void) |
745 | { | |
493df71c JB |
746 | int r; |
747 | ||
748 | r = dm_exception_store_type_register(&_persistent_type); | |
749 | if (r) { | |
750 | DMERR("Unable to register persistent exception store type"); | |
751 | return r; | |
752 | } | |
753 | ||
754 | r = dm_exception_store_type_register(&_persistent_compat_type); | |
755 | if (r) { | |
756 | DMERR("Unable to register old-style persistent exception " | |
757 | "store type"); | |
758 | dm_exception_store_type_unregister(&_persistent_type); | |
759 | return r; | |
760 | } | |
761 | ||
762 | return r; | |
4db6bfe0 AK |
763 | } |
764 | ||
765 | void dm_persistent_snapshot_exit(void) | |
766 | { | |
493df71c JB |
767 | dm_exception_store_type_unregister(&_persistent_type); |
768 | dm_exception_store_type_unregister(&_persistent_compat_type); | |
4db6bfe0 | 769 | } |