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 | ||
61578dcd MP |
108 | /* |
109 | * An area used for header. The header can be written | |
110 | * concurrently with metadata (when invalidating the snapshot), | |
111 | * so it needs a separate buffer. | |
112 | */ | |
113 | void *header_area; | |
114 | ||
4db6bfe0 AK |
115 | /* |
116 | * Used to keep track of which metadata area the data in | |
117 | * 'chunk' refers to. | |
118 | */ | |
119 | chunk_t current_area; | |
120 | ||
121 | /* | |
122 | * The next free chunk for an exception. | |
123 | */ | |
124 | chunk_t next_free; | |
125 | ||
126 | /* | |
127 | * The index of next free exception in the current | |
128 | * metadata area. | |
129 | */ | |
130 | uint32_t current_committed; | |
131 | ||
132 | atomic_t pending_count; | |
133 | uint32_t callback_count; | |
134 | struct commit_callback *callbacks; | |
135 | struct dm_io_client *io_client; | |
136 | ||
137 | struct workqueue_struct *metadata_wq; | |
138 | }; | |
139 | ||
140 | static unsigned sectors_to_pages(unsigned sectors) | |
141 | { | |
142 | return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9); | |
143 | } | |
144 | ||
145 | static int alloc_area(struct pstore *ps) | |
146 | { | |
147 | int r = -ENOMEM; | |
148 | size_t len; | |
149 | ||
71fab00a | 150 | len = ps->store->chunk_size << SECTOR_SHIFT; |
4db6bfe0 AK |
151 | |
152 | /* | |
153 | * Allocate the chunk_size block of memory that will hold | |
154 | * a single metadata area. | |
155 | */ | |
156 | ps->area = vmalloc(len); | |
157 | if (!ps->area) | |
61578dcd | 158 | goto err_area; |
4db6bfe0 AK |
159 | |
160 | ps->zero_area = vmalloc(len); | |
61578dcd MP |
161 | if (!ps->zero_area) |
162 | goto err_zero_area; | |
4db6bfe0 AK |
163 | memset(ps->zero_area, 0, len); |
164 | ||
61578dcd MP |
165 | ps->header_area = vmalloc(len); |
166 | if (!ps->header_area) | |
167 | goto err_header_area; | |
168 | ||
4db6bfe0 | 169 | return 0; |
61578dcd MP |
170 | |
171 | err_header_area: | |
172 | vfree(ps->zero_area); | |
173 | ||
174 | err_zero_area: | |
175 | vfree(ps->area); | |
176 | ||
177 | err_area: | |
178 | return r; | |
4db6bfe0 AK |
179 | } |
180 | ||
181 | static void free_area(struct pstore *ps) | |
182 | { | |
a32079ce JB |
183 | if (ps->area) |
184 | vfree(ps->area); | |
4db6bfe0 | 185 | ps->area = NULL; |
a32079ce JB |
186 | |
187 | if (ps->zero_area) | |
188 | vfree(ps->zero_area); | |
4db6bfe0 | 189 | ps->zero_area = NULL; |
61578dcd MP |
190 | |
191 | if (ps->header_area) | |
192 | vfree(ps->header_area); | |
193 | ps->header_area = NULL; | |
4db6bfe0 AK |
194 | } |
195 | ||
196 | struct mdata_req { | |
197 | struct dm_io_region *where; | |
198 | struct dm_io_request *io_req; | |
199 | struct work_struct work; | |
200 | int result; | |
201 | }; | |
202 | ||
203 | static void do_metadata(struct work_struct *work) | |
204 | { | |
205 | struct mdata_req *req = container_of(work, struct mdata_req, work); | |
206 | ||
207 | req->result = dm_io(req->io_req, 1, req->where, NULL); | |
208 | } | |
209 | ||
210 | /* | |
211 | * Read or write a chunk aligned and sized block of data from a device. | |
212 | */ | |
02d2fd31 MP |
213 | static int chunk_io(struct pstore *ps, void *area, chunk_t chunk, int rw, |
214 | int metadata) | |
4db6bfe0 AK |
215 | { |
216 | struct dm_io_region where = { | |
71fab00a JB |
217 | .bdev = ps->store->cow->bdev, |
218 | .sector = ps->store->chunk_size * chunk, | |
219 | .count = ps->store->chunk_size, | |
4db6bfe0 AK |
220 | }; |
221 | struct dm_io_request io_req = { | |
222 | .bi_rw = rw, | |
223 | .mem.type = DM_IO_VMA, | |
02d2fd31 | 224 | .mem.ptr.vma = area, |
4db6bfe0 AK |
225 | .client = ps->io_client, |
226 | .notify.fn = NULL, | |
227 | }; | |
228 | struct mdata_req req; | |
229 | ||
230 | if (!metadata) | |
231 | return dm_io(&io_req, 1, &where, NULL); | |
232 | ||
233 | req.where = &where; | |
234 | req.io_req = &io_req; | |
235 | ||
236 | /* | |
237 | * Issue the synchronous I/O from a different thread | |
238 | * to avoid generic_make_request recursion. | |
239 | */ | |
240 | INIT_WORK(&req.work, do_metadata); | |
241 | queue_work(ps->metadata_wq, &req.work); | |
242 | flush_workqueue(ps->metadata_wq); | |
243 | ||
244 | return req.result; | |
245 | } | |
246 | ||
247 | /* | |
248 | * Convert a metadata area index to a chunk index. | |
249 | */ | |
250 | static chunk_t area_location(struct pstore *ps, chunk_t area) | |
251 | { | |
252 | return 1 + ((ps->exceptions_per_area + 1) * area); | |
253 | } | |
254 | ||
255 | /* | |
256 | * Read or write a metadata area. Remembering to skip the first | |
257 | * chunk which holds the header. | |
258 | */ | |
259 | static int area_io(struct pstore *ps, int rw) | |
260 | { | |
261 | int r; | |
262 | chunk_t chunk; | |
263 | ||
264 | chunk = area_location(ps, ps->current_area); | |
265 | ||
02d2fd31 | 266 | r = chunk_io(ps, ps->area, chunk, rw, 0); |
4db6bfe0 AK |
267 | if (r) |
268 | return r; | |
269 | ||
270 | return 0; | |
271 | } | |
272 | ||
273 | static void zero_memory_area(struct pstore *ps) | |
274 | { | |
71fab00a | 275 | memset(ps->area, 0, ps->store->chunk_size << SECTOR_SHIFT); |
4db6bfe0 AK |
276 | } |
277 | ||
278 | static int zero_disk_area(struct pstore *ps, chunk_t area) | |
279 | { | |
02d2fd31 | 280 | return chunk_io(ps, ps->zero_area, area_location(ps, area), WRITE, 0); |
4db6bfe0 AK |
281 | } |
282 | ||
283 | static int read_header(struct pstore *ps, int *new_snapshot) | |
284 | { | |
285 | int r; | |
286 | struct disk_header *dh; | |
287 | chunk_t chunk_size; | |
288 | int chunk_size_supplied = 1; | |
ae0b7448 | 289 | char *chunk_err; |
4db6bfe0 AK |
290 | |
291 | /* | |
292 | * Use default chunk size (or hardsect_size, if larger) if none supplied | |
293 | */ | |
71fab00a JB |
294 | if (!ps->store->chunk_size) { |
295 | ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS, | |
e1defc4f | 296 | bdev_logical_block_size(ps->store->cow->bdev) >> 9); |
71fab00a JB |
297 | ps->store->chunk_mask = ps->store->chunk_size - 1; |
298 | ps->store->chunk_shift = ffs(ps->store->chunk_size) - 1; | |
4db6bfe0 AK |
299 | chunk_size_supplied = 0; |
300 | } | |
301 | ||
71fab00a JB |
302 | ps->io_client = dm_io_client_create(sectors_to_pages(ps->store-> |
303 | chunk_size)); | |
4db6bfe0 AK |
304 | if (IS_ERR(ps->io_client)) |
305 | return PTR_ERR(ps->io_client); | |
306 | ||
307 | r = alloc_area(ps); | |
308 | if (r) | |
309 | return r; | |
310 | ||
61578dcd | 311 | r = chunk_io(ps, ps->header_area, 0, READ, 1); |
4db6bfe0 AK |
312 | if (r) |
313 | goto bad; | |
314 | ||
61578dcd | 315 | dh = ps->header_area; |
4db6bfe0 AK |
316 | |
317 | if (le32_to_cpu(dh->magic) == 0) { | |
318 | *new_snapshot = 1; | |
319 | return 0; | |
320 | } | |
321 | ||
322 | if (le32_to_cpu(dh->magic) != SNAP_MAGIC) { | |
323 | DMWARN("Invalid or corrupt snapshot"); | |
324 | r = -ENXIO; | |
325 | goto bad; | |
326 | } | |
327 | ||
328 | *new_snapshot = 0; | |
329 | ps->valid = le32_to_cpu(dh->valid); | |
330 | ps->version = le32_to_cpu(dh->version); | |
331 | chunk_size = le32_to_cpu(dh->chunk_size); | |
332 | ||
ae0b7448 | 333 | if (ps->store->chunk_size == chunk_size) |
4db6bfe0 AK |
334 | return 0; |
335 | ||
ae0b7448 MP |
336 | if (chunk_size_supplied) |
337 | DMWARN("chunk size %llu in device metadata overrides " | |
338 | "table chunk size of %llu.", | |
339 | (unsigned long long)chunk_size, | |
340 | (unsigned long long)ps->store->chunk_size); | |
4db6bfe0 AK |
341 | |
342 | /* We had a bogus chunk_size. Fix stuff up. */ | |
343 | free_area(ps); | |
344 | ||
ae0b7448 MP |
345 | r = dm_exception_store_set_chunk_size(ps->store, chunk_size, |
346 | &chunk_err); | |
347 | if (r) { | |
348 | DMERR("invalid on-disk chunk size %llu: %s.", | |
349 | (unsigned long long)chunk_size, chunk_err); | |
350 | return r; | |
351 | } | |
4db6bfe0 | 352 | |
71fab00a | 353 | r = dm_io_client_resize(sectors_to_pages(ps->store->chunk_size), |
4db6bfe0 AK |
354 | ps->io_client); |
355 | if (r) | |
356 | return r; | |
357 | ||
358 | r = alloc_area(ps); | |
359 | return r; | |
360 | ||
361 | bad: | |
362 | free_area(ps); | |
363 | return r; | |
364 | } | |
365 | ||
366 | static int write_header(struct pstore *ps) | |
367 | { | |
368 | struct disk_header *dh; | |
369 | ||
61578dcd | 370 | memset(ps->header_area, 0, ps->store->chunk_size << SECTOR_SHIFT); |
4db6bfe0 | 371 | |
61578dcd | 372 | dh = ps->header_area; |
4db6bfe0 AK |
373 | dh->magic = cpu_to_le32(SNAP_MAGIC); |
374 | dh->valid = cpu_to_le32(ps->valid); | |
375 | dh->version = cpu_to_le32(ps->version); | |
71fab00a | 376 | dh->chunk_size = cpu_to_le32(ps->store->chunk_size); |
4db6bfe0 | 377 | |
61578dcd | 378 | return chunk_io(ps, ps->header_area, 0, WRITE, 1); |
4db6bfe0 AK |
379 | } |
380 | ||
381 | /* | |
382 | * Access functions for the disk exceptions, these do the endian conversions. | |
383 | */ | |
384 | static struct disk_exception *get_exception(struct pstore *ps, uint32_t index) | |
385 | { | |
386 | BUG_ON(index >= ps->exceptions_per_area); | |
387 | ||
388 | return ((struct disk_exception *) ps->area) + index; | |
389 | } | |
390 | ||
391 | static void read_exception(struct pstore *ps, | |
392 | uint32_t index, struct disk_exception *result) | |
393 | { | |
394 | struct disk_exception *e = get_exception(ps, index); | |
395 | ||
396 | /* copy it */ | |
397 | result->old_chunk = le64_to_cpu(e->old_chunk); | |
398 | result->new_chunk = le64_to_cpu(e->new_chunk); | |
399 | } | |
400 | ||
401 | static void write_exception(struct pstore *ps, | |
402 | uint32_t index, struct disk_exception *de) | |
403 | { | |
404 | struct disk_exception *e = get_exception(ps, index); | |
405 | ||
406 | /* copy it */ | |
407 | e->old_chunk = cpu_to_le64(de->old_chunk); | |
408 | e->new_chunk = cpu_to_le64(de->new_chunk); | |
409 | } | |
410 | ||
411 | /* | |
412 | * Registers the exceptions that are present in the current area. | |
413 | * 'full' is filled in to indicate if the area has been | |
414 | * filled. | |
415 | */ | |
a159c1ac JB |
416 | static int insert_exceptions(struct pstore *ps, |
417 | int (*callback)(void *callback_context, | |
418 | chunk_t old, chunk_t new), | |
419 | void *callback_context, | |
420 | int *full) | |
4db6bfe0 AK |
421 | { |
422 | int r; | |
423 | unsigned int i; | |
424 | struct disk_exception de; | |
425 | ||
426 | /* presume the area is full */ | |
427 | *full = 1; | |
428 | ||
429 | for (i = 0; i < ps->exceptions_per_area; i++) { | |
430 | read_exception(ps, i, &de); | |
431 | ||
432 | /* | |
433 | * If the new_chunk is pointing at the start of | |
434 | * the COW device, where the first metadata area | |
435 | * is we know that we've hit the end of the | |
436 | * exceptions. Therefore the area is not full. | |
437 | */ | |
438 | if (de.new_chunk == 0LL) { | |
439 | ps->current_committed = i; | |
440 | *full = 0; | |
441 | break; | |
442 | } | |
443 | ||
444 | /* | |
445 | * Keep track of the start of the free chunks. | |
446 | */ | |
447 | if (ps->next_free <= de.new_chunk) | |
448 | ps->next_free = de.new_chunk + 1; | |
449 | ||
450 | /* | |
451 | * Otherwise we add the exception to the snapshot. | |
452 | */ | |
a159c1ac | 453 | r = callback(callback_context, de.old_chunk, de.new_chunk); |
4db6bfe0 AK |
454 | if (r) |
455 | return r; | |
456 | } | |
457 | ||
458 | return 0; | |
459 | } | |
460 | ||
a159c1ac JB |
461 | static int read_exceptions(struct pstore *ps, |
462 | int (*callback)(void *callback_context, chunk_t old, | |
463 | chunk_t new), | |
464 | void *callback_context) | |
4db6bfe0 AK |
465 | { |
466 | int r, full = 1; | |
467 | ||
468 | /* | |
469 | * Keeping reading chunks and inserting exceptions until | |
470 | * we find a partially full area. | |
471 | */ | |
472 | for (ps->current_area = 0; full; ps->current_area++) { | |
473 | r = area_io(ps, READ); | |
474 | if (r) | |
475 | return r; | |
476 | ||
a159c1ac | 477 | r = insert_exceptions(ps, callback, callback_context, &full); |
4db6bfe0 AK |
478 | if (r) |
479 | return r; | |
480 | } | |
481 | ||
482 | ps->current_area--; | |
483 | ||
484 | return 0; | |
485 | } | |
486 | ||
487 | static struct pstore *get_info(struct dm_exception_store *store) | |
488 | { | |
489 | return (struct pstore *) store->context; | |
490 | } | |
491 | ||
492 | static void persistent_fraction_full(struct dm_exception_store *store, | |
493 | sector_t *numerator, sector_t *denominator) | |
494 | { | |
d0216849 | 495 | *numerator = get_info(store)->next_free * store->chunk_size; |
49beb2b8 | 496 | *denominator = get_dev_size(store->cow->bdev); |
4db6bfe0 AK |
497 | } |
498 | ||
493df71c | 499 | static void persistent_dtr(struct dm_exception_store *store) |
4db6bfe0 AK |
500 | { |
501 | struct pstore *ps = get_info(store); | |
502 | ||
503 | destroy_workqueue(ps->metadata_wq); | |
a32079ce JB |
504 | |
505 | /* Created in read_header */ | |
506 | if (ps->io_client) | |
507 | dm_io_client_destroy(ps->io_client); | |
4db6bfe0 | 508 | free_area(ps); |
a32079ce JB |
509 | |
510 | /* Allocated in persistent_read_metadata */ | |
511 | if (ps->callbacks) | |
512 | vfree(ps->callbacks); | |
513 | ||
4db6bfe0 AK |
514 | kfree(ps); |
515 | } | |
516 | ||
a159c1ac JB |
517 | static int persistent_read_metadata(struct dm_exception_store *store, |
518 | int (*callback)(void *callback_context, | |
519 | chunk_t old, chunk_t new), | |
520 | void *callback_context) | |
4db6bfe0 AK |
521 | { |
522 | int r, uninitialized_var(new_snapshot); | |
523 | struct pstore *ps = get_info(store); | |
524 | ||
525 | /* | |
526 | * Read the snapshot header. | |
527 | */ | |
528 | r = read_header(ps, &new_snapshot); | |
529 | if (r) | |
530 | return r; | |
531 | ||
532 | /* | |
533 | * Now we know correct chunk_size, complete the initialisation. | |
534 | */ | |
71fab00a JB |
535 | ps->exceptions_per_area = (ps->store->chunk_size << SECTOR_SHIFT) / |
536 | sizeof(struct disk_exception); | |
4db6bfe0 AK |
537 | ps->callbacks = dm_vcalloc(ps->exceptions_per_area, |
538 | sizeof(*ps->callbacks)); | |
539 | if (!ps->callbacks) | |
540 | return -ENOMEM; | |
541 | ||
542 | /* | |
543 | * Do we need to setup a new snapshot ? | |
544 | */ | |
545 | if (new_snapshot) { | |
546 | r = write_header(ps); | |
547 | if (r) { | |
548 | DMWARN("write_header failed"); | |
549 | return r; | |
550 | } | |
551 | ||
552 | ps->current_area = 0; | |
553 | zero_memory_area(ps); | |
554 | r = zero_disk_area(ps, 0); | |
555 | if (r) { | |
556 | DMWARN("zero_disk_area(0) failed"); | |
557 | return r; | |
558 | } | |
559 | } else { | |
560 | /* | |
561 | * Sanity checks. | |
562 | */ | |
563 | if (ps->version != SNAPSHOT_DISK_VERSION) { | |
564 | DMWARN("unable to handle snapshot disk version %d", | |
565 | ps->version); | |
566 | return -EINVAL; | |
567 | } | |
568 | ||
569 | /* | |
570 | * Metadata are valid, but snapshot is invalidated | |
571 | */ | |
572 | if (!ps->valid) | |
573 | return 1; | |
574 | ||
575 | /* | |
576 | * Read the metadata. | |
577 | */ | |
a159c1ac | 578 | r = read_exceptions(ps, callback, callback_context); |
4db6bfe0 AK |
579 | if (r) |
580 | return r; | |
581 | } | |
582 | ||
583 | return 0; | |
584 | } | |
585 | ||
a159c1ac JB |
586 | static int persistent_prepare_exception(struct dm_exception_store *store, |
587 | struct dm_snap_exception *e) | |
4db6bfe0 AK |
588 | { |
589 | struct pstore *ps = get_info(store); | |
590 | uint32_t stride; | |
591 | chunk_t next_free; | |
49beb2b8 | 592 | sector_t size = get_dev_size(store->cow->bdev); |
4db6bfe0 AK |
593 | |
594 | /* Is there enough room ? */ | |
d0216849 | 595 | if (size < ((ps->next_free + 1) * store->chunk_size)) |
4db6bfe0 AK |
596 | return -ENOSPC; |
597 | ||
598 | e->new_chunk = ps->next_free; | |
599 | ||
600 | /* | |
601 | * Move onto the next free pending, making sure to take | |
602 | * into account the location of the metadata chunks. | |
603 | */ | |
604 | stride = (ps->exceptions_per_area + 1); | |
605 | next_free = ++ps->next_free; | |
606 | if (sector_div(next_free, stride) == 1) | |
607 | ps->next_free++; | |
608 | ||
609 | atomic_inc(&ps->pending_count); | |
610 | return 0; | |
611 | } | |
612 | ||
a159c1ac JB |
613 | static void persistent_commit_exception(struct dm_exception_store *store, |
614 | struct dm_snap_exception *e, | |
615 | void (*callback) (void *, int success), | |
616 | void *callback_context) | |
4db6bfe0 AK |
617 | { |
618 | unsigned int i; | |
619 | struct pstore *ps = get_info(store); | |
620 | struct disk_exception de; | |
621 | struct commit_callback *cb; | |
622 | ||
623 | de.old_chunk = e->old_chunk; | |
624 | de.new_chunk = e->new_chunk; | |
625 | write_exception(ps, ps->current_committed++, &de); | |
626 | ||
627 | /* | |
628 | * Add the callback to the back of the array. This code | |
629 | * is the only place where the callback array is | |
630 | * manipulated, and we know that it will never be called | |
631 | * multiple times concurrently. | |
632 | */ | |
633 | cb = ps->callbacks + ps->callback_count++; | |
634 | cb->callback = callback; | |
635 | cb->context = callback_context; | |
636 | ||
637 | /* | |
638 | * If there are exceptions in flight and we have not yet | |
639 | * filled this metadata area there's nothing more to do. | |
640 | */ | |
641 | if (!atomic_dec_and_test(&ps->pending_count) && | |
642 | (ps->current_committed != ps->exceptions_per_area)) | |
643 | return; | |
644 | ||
645 | /* | |
646 | * If we completely filled the current area, then wipe the next one. | |
647 | */ | |
648 | if ((ps->current_committed == ps->exceptions_per_area) && | |
649 | zero_disk_area(ps, ps->current_area + 1)) | |
650 | ps->valid = 0; | |
651 | ||
652 | /* | |
653 | * Commit exceptions to disk. | |
654 | */ | |
2bd02345 | 655 | if (ps->valid && area_io(ps, WRITE_BARRIER)) |
4db6bfe0 AK |
656 | ps->valid = 0; |
657 | ||
658 | /* | |
659 | * Advance to the next area if this one is full. | |
660 | */ | |
661 | if (ps->current_committed == ps->exceptions_per_area) { | |
662 | ps->current_committed = 0; | |
663 | ps->current_area++; | |
664 | zero_memory_area(ps); | |
665 | } | |
666 | ||
667 | for (i = 0; i < ps->callback_count; i++) { | |
668 | cb = ps->callbacks + i; | |
669 | cb->callback(cb->context, ps->valid); | |
670 | } | |
671 | ||
672 | ps->callback_count = 0; | |
673 | } | |
674 | ||
a159c1ac | 675 | static void persistent_drop_snapshot(struct dm_exception_store *store) |
4db6bfe0 AK |
676 | { |
677 | struct pstore *ps = get_info(store); | |
678 | ||
679 | ps->valid = 0; | |
680 | if (write_header(ps)) | |
681 | DMWARN("write header failed"); | |
682 | } | |
683 | ||
493df71c JB |
684 | static int persistent_ctr(struct dm_exception_store *store, |
685 | unsigned argc, char **argv) | |
4db6bfe0 AK |
686 | { |
687 | struct pstore *ps; | |
688 | ||
689 | /* allocate the pstore */ | |
a32079ce | 690 | ps = kzalloc(sizeof(*ps), GFP_KERNEL); |
4db6bfe0 AK |
691 | if (!ps) |
692 | return -ENOMEM; | |
693 | ||
71fab00a | 694 | ps->store = store; |
4db6bfe0 AK |
695 | ps->valid = 1; |
696 | ps->version = SNAPSHOT_DISK_VERSION; | |
697 | ps->area = NULL; | |
61578dcd MP |
698 | ps->zero_area = NULL; |
699 | ps->header_area = NULL; | |
4db6bfe0 AK |
700 | ps->next_free = 2; /* skipping the header and first area */ |
701 | ps->current_committed = 0; | |
702 | ||
703 | ps->callback_count = 0; | |
704 | atomic_set(&ps->pending_count, 0); | |
705 | ps->callbacks = NULL; | |
706 | ||
707 | ps->metadata_wq = create_singlethread_workqueue("ksnaphd"); | |
708 | if (!ps->metadata_wq) { | |
709 | kfree(ps); | |
710 | DMERR("couldn't start header metadata update thread"); | |
711 | return -ENOMEM; | |
712 | } | |
713 | ||
4db6bfe0 AK |
714 | store->context = ps; |
715 | ||
716 | return 0; | |
717 | } | |
718 | ||
1e302a92 JB |
719 | static unsigned persistent_status(struct dm_exception_store *store, |
720 | status_type_t status, char *result, | |
721 | unsigned maxlen) | |
493df71c | 722 | { |
1e302a92 JB |
723 | unsigned sz = 0; |
724 | ||
725 | switch (status) { | |
726 | case STATUSTYPE_INFO: | |
727 | break; | |
728 | case STATUSTYPE_TABLE: | |
729 | DMEMIT(" %s P %llu", store->cow->name, | |
730 | (unsigned long long)store->chunk_size); | |
731 | } | |
493df71c JB |
732 | |
733 | return sz; | |
734 | } | |
735 | ||
736 | static struct dm_exception_store_type _persistent_type = { | |
737 | .name = "persistent", | |
738 | .module = THIS_MODULE, | |
739 | .ctr = persistent_ctr, | |
740 | .dtr = persistent_dtr, | |
741 | .read_metadata = persistent_read_metadata, | |
742 | .prepare_exception = persistent_prepare_exception, | |
743 | .commit_exception = persistent_commit_exception, | |
744 | .drop_snapshot = persistent_drop_snapshot, | |
745 | .fraction_full = persistent_fraction_full, | |
746 | .status = persistent_status, | |
747 | }; | |
748 | ||
749 | static struct dm_exception_store_type _persistent_compat_type = { | |
750 | .name = "P", | |
751 | .module = THIS_MODULE, | |
752 | .ctr = persistent_ctr, | |
753 | .dtr = persistent_dtr, | |
754 | .read_metadata = persistent_read_metadata, | |
755 | .prepare_exception = persistent_prepare_exception, | |
756 | .commit_exception = persistent_commit_exception, | |
757 | .drop_snapshot = persistent_drop_snapshot, | |
758 | .fraction_full = persistent_fraction_full, | |
759 | .status = persistent_status, | |
760 | }; | |
761 | ||
4db6bfe0 AK |
762 | int dm_persistent_snapshot_init(void) |
763 | { | |
493df71c JB |
764 | int r; |
765 | ||
766 | r = dm_exception_store_type_register(&_persistent_type); | |
767 | if (r) { | |
768 | DMERR("Unable to register persistent exception store type"); | |
769 | return r; | |
770 | } | |
771 | ||
772 | r = dm_exception_store_type_register(&_persistent_compat_type); | |
773 | if (r) { | |
774 | DMERR("Unable to register old-style persistent exception " | |
775 | "store type"); | |
776 | dm_exception_store_type_unregister(&_persistent_type); | |
777 | return r; | |
778 | } | |
779 | ||
780 | return r; | |
4db6bfe0 AK |
781 | } |
782 | ||
783 | void dm_persistent_snapshot_exit(void) | |
784 | { | |
493df71c JB |
785 | dm_exception_store_type_unregister(&_persistent_type); |
786 | dm_exception_store_type_unregister(&_persistent_compat_type); | |
4db6bfe0 | 787 | } |