Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
6cca1e7a | 2 | * dm-exception-store.c |
1da177e4 LT |
3 | * |
4 | * Copyright (C) 2001-2002 Sistina Software (UK) Limited. | |
6cca1e7a | 5 | * Copyright (C) 2006 Red Hat GmbH |
1da177e4 LT |
6 | * |
7 | * This file is released under the GPL. | |
8 | */ | |
9 | ||
1da177e4 | 10 | #include "dm-snap.h" |
1da177e4 LT |
11 | |
12 | #include <linux/mm.h> | |
13 | #include <linux/pagemap.h> | |
14 | #include <linux/vmalloc.h> | |
15 | #include <linux/slab.h> | |
a765e20e AK |
16 | #include <linux/dm-io.h> |
17 | #include <linux/dm-kcopyd.h> | |
1da177e4 | 18 | |
72d94861 | 19 | #define DM_MSG_PREFIX "snapshots" |
4c7e3bf4 | 20 | #define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */ |
72d94861 | 21 | |
1da177e4 LT |
22 | /*----------------------------------------------------------------- |
23 | * Persistent snapshots, by persistent we mean that the snapshot | |
24 | * will survive a reboot. | |
25 | *---------------------------------------------------------------*/ | |
26 | ||
27 | /* | |
28 | * We need to store a record of which parts of the origin have | |
29 | * been copied to the snapshot device. The snapshot code | |
30 | * requires that we copy exception chunks to chunk aligned areas | |
31 | * of the COW store. It makes sense therefore, to store the | |
32 | * metadata in chunk size blocks. | |
33 | * | |
34 | * There is no backward or forward compatibility implemented, | |
35 | * snapshots with different disk versions than the kernel will | |
36 | * not be usable. It is expected that "lvcreate" will blank out | |
37 | * the start of a fresh COW device before calling the snapshot | |
38 | * constructor. | |
39 | * | |
40 | * The first chunk of the COW device just contains the header. | |
41 | * After this there is a chunk filled with exception metadata, | |
42 | * followed by as many exception chunks as can fit in the | |
43 | * metadata areas. | |
44 | * | |
45 | * All on disk structures are in little-endian format. The end | |
46 | * of the exceptions info is indicated by an exception with a | |
47 | * new_chunk of 0, which is invalid since it would point to the | |
48 | * header chunk. | |
49 | */ | |
50 | ||
51 | /* | |
52 | * Magic for persistent snapshots: "SnAp" - Feeble isn't it. | |
53 | */ | |
54 | #define SNAP_MAGIC 0x70416e53 | |
55 | ||
56 | /* | |
57 | * The on-disk version of the metadata. | |
58 | */ | |
59 | #define SNAPSHOT_DISK_VERSION 1 | |
60 | ||
61 | struct disk_header { | |
62 | uint32_t magic; | |
63 | ||
64 | /* | |
65 | * Is this snapshot valid. There is no way of recovering | |
66 | * an invalid snapshot. | |
67 | */ | |
68 | uint32_t valid; | |
69 | ||
70 | /* | |
71 | * Simple, incrementing version. no backward | |
72 | * compatibility. | |
73 | */ | |
74 | uint32_t version; | |
75 | ||
76 | /* In sectors */ | |
77 | uint32_t chunk_size; | |
78 | }; | |
79 | ||
80 | struct disk_exception { | |
81 | uint64_t old_chunk; | |
82 | uint64_t new_chunk; | |
83 | }; | |
84 | ||
85 | struct commit_callback { | |
86 | void (*callback)(void *, int success); | |
87 | void *context; | |
88 | }; | |
89 | ||
90 | /* | |
91 | * The top level structure for a persistent exception store. | |
92 | */ | |
93 | struct pstore { | |
94 | struct dm_snapshot *snap; /* up pointer to my snapshot */ | |
95 | int version; | |
96 | int valid; | |
1da177e4 LT |
97 | uint32_t exceptions_per_area; |
98 | ||
99 | /* | |
100 | * Now that we have an asynchronous kcopyd there is no | |
101 | * need for large chunk sizes, so it wont hurt to have a | |
102 | * whole chunks worth of metadata in memory at once. | |
103 | */ | |
104 | void *area; | |
105 | ||
7c9e6c17 AK |
106 | /* |
107 | * An area of zeros used to clear the next area. | |
108 | */ | |
109 | void *zero_area; | |
110 | ||
1da177e4 LT |
111 | /* |
112 | * Used to keep track of which metadata area the data in | |
113 | * 'chunk' refers to. | |
114 | */ | |
fd14acf6 | 115 | chunk_t current_area; |
1da177e4 LT |
116 | |
117 | /* | |
118 | * The next free chunk for an exception. | |
119 | */ | |
fd14acf6 | 120 | chunk_t next_free; |
1da177e4 LT |
121 | |
122 | /* | |
123 | * The index of next free exception in the current | |
124 | * metadata area. | |
125 | */ | |
126 | uint32_t current_committed; | |
127 | ||
128 | atomic_t pending_count; | |
129 | uint32_t callback_count; | |
130 | struct commit_callback *callbacks; | |
6cca1e7a | 131 | struct dm_io_client *io_client; |
fcac03ab MB |
132 | |
133 | struct workqueue_struct *metadata_wq; | |
1da177e4 LT |
134 | }; |
135 | ||
028867ac | 136 | static unsigned sectors_to_pages(unsigned sectors) |
1da177e4 | 137 | { |
92436262 | 138 | return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9); |
1da177e4 LT |
139 | } |
140 | ||
141 | static int alloc_area(struct pstore *ps) | |
142 | { | |
143 | int r = -ENOMEM; | |
144 | size_t len; | |
145 | ||
c51c2752 | 146 | len = ps->snap->chunk_size << SECTOR_SHIFT; |
1da177e4 LT |
147 | |
148 | /* | |
149 | * Allocate the chunk_size block of memory that will hold | |
150 | * a single metadata area. | |
151 | */ | |
152 | ps->area = vmalloc(len); | |
153 | if (!ps->area) | |
154 | return r; | |
155 | ||
7c9e6c17 AK |
156 | ps->zero_area = vmalloc(len); |
157 | if (!ps->zero_area) { | |
158 | vfree(ps->area); | |
159 | return r; | |
160 | } | |
161 | memset(ps->zero_area, 0, len); | |
162 | ||
1da177e4 LT |
163 | return 0; |
164 | } | |
165 | ||
166 | static void free_area(struct pstore *ps) | |
167 | { | |
168 | vfree(ps->area); | |
4c7e3bf4 | 169 | ps->area = NULL; |
7c9e6c17 AK |
170 | vfree(ps->zero_area); |
171 | ps->zero_area = NULL; | |
1da177e4 LT |
172 | } |
173 | ||
fcac03ab | 174 | struct mdata_req { |
22a1ceb1 | 175 | struct dm_io_region *where; |
fcac03ab MB |
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 | ||
1da177e4 LT |
188 | /* |
189 | * Read or write a chunk aligned and sized block of data from a device. | |
190 | */ | |
fd14acf6 | 191 | static int chunk_io(struct pstore *ps, chunk_t chunk, int rw, int metadata) |
1da177e4 | 192 | { |
22a1ceb1 | 193 | struct dm_io_region where = { |
6cca1e7a HM |
194 | .bdev = ps->snap->cow->bdev, |
195 | .sector = ps->snap->chunk_size * chunk, | |
196 | .count = ps->snap->chunk_size, | |
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 | }; | |
fcac03ab MB |
205 | struct mdata_req req; |
206 | ||
207 | if (!metadata) | |
208 | return dm_io(&io_req, 1, &where, NULL); | |
6cca1e7a | 209 | |
fcac03ab MB |
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; | |
1da177e4 LT |
222 | } |
223 | ||
a481db78 MP |
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 | ||
1da177e4 LT |
232 | /* |
233 | * Read or write a metadata area. Remembering to skip the first | |
234 | * chunk which holds the header. | |
235 | */ | |
7c9e6c17 | 236 | static int area_io(struct pstore *ps, int rw) |
1da177e4 LT |
237 | { |
238 | int r; | |
fd14acf6 | 239 | chunk_t chunk; |
1da177e4 | 240 | |
7c9e6c17 | 241 | chunk = area_location(ps, ps->current_area); |
1da177e4 | 242 | |
fcac03ab | 243 | r = chunk_io(ps, chunk, rw, 0); |
1da177e4 LT |
244 | if (r) |
245 | return r; | |
246 | ||
1da177e4 LT |
247 | return 0; |
248 | } | |
249 | ||
7c9e6c17 | 250 | static void zero_memory_area(struct pstore *ps) |
1da177e4 | 251 | { |
c51c2752 | 252 | memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT); |
7c9e6c17 AK |
253 | } |
254 | ||
255 | static int zero_disk_area(struct pstore *ps, chunk_t area) | |
256 | { | |
257 | struct dm_io_region where = { | |
258 | .bdev = ps->snap->cow->bdev, | |
259 | .sector = ps->snap->chunk_size * area_location(ps, area), | |
260 | .count = ps->snap->chunk_size, | |
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); | |
1da177e4 LT |
271 | } |
272 | ||
273 | static int read_header(struct pstore *ps, int *new_snapshot) | |
274 | { | |
275 | int r; | |
276 | struct disk_header *dh; | |
c51c2752 | 277 | chunk_t chunk_size; |
4c7e3bf4 | 278 | int chunk_size_supplied = 1; |
1da177e4 | 279 | |
4c7e3bf4 MM |
280 | /* |
281 | * Use default chunk size (or hardsect_size, if larger) if none supplied | |
282 | */ | |
283 | if (!ps->snap->chunk_size) { | |
284 | ps->snap->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS, | |
285 | bdev_hardsect_size(ps->snap->cow->bdev) >> 9); | |
286 | ps->snap->chunk_mask = ps->snap->chunk_size - 1; | |
287 | ps->snap->chunk_shift = ffs(ps->snap->chunk_size) - 1; | |
288 | chunk_size_supplied = 0; | |
289 | } | |
290 | ||
6cca1e7a HM |
291 | ps->io_client = dm_io_client_create(sectors_to_pages(ps->snap-> |
292 | chunk_size)); | |
293 | if (IS_ERR(ps->io_client)) | |
294 | return PTR_ERR(ps->io_client); | |
1da177e4 | 295 | |
4c7e3bf4 MM |
296 | r = alloc_area(ps); |
297 | if (r) | |
6cca1e7a | 298 | return r; |
4c7e3bf4 | 299 | |
fcac03ab | 300 | r = chunk_io(ps, 0, READ, 1); |
4c7e3bf4 | 301 | if (r) |
6cca1e7a | 302 | goto bad; |
4c7e3bf4 | 303 | |
1da177e4 LT |
304 | dh = (struct disk_header *) ps->area; |
305 | ||
306 | if (le32_to_cpu(dh->magic) == 0) { | |
307 | *new_snapshot = 1; | |
4c7e3bf4 MM |
308 | return 0; |
309 | } | |
1da177e4 | 310 | |
4c7e3bf4 MM |
311 | if (le32_to_cpu(dh->magic) != SNAP_MAGIC) { |
312 | DMWARN("Invalid or corrupt snapshot"); | |
1da177e4 | 313 | r = -ENXIO; |
6cca1e7a | 314 | goto bad; |
1da177e4 LT |
315 | } |
316 | ||
4c7e3bf4 MM |
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 | ||
322 | if (!chunk_size_supplied || ps->snap->chunk_size == chunk_size) | |
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, | |
328 | (unsigned long long)ps->snap->chunk_size); | |
329 | ||
330 | /* We had a bogus chunk_size. Fix stuff up. */ | |
4c7e3bf4 MM |
331 | free_area(ps); |
332 | ||
333 | ps->snap->chunk_size = chunk_size; | |
334 | ps->snap->chunk_mask = chunk_size - 1; | |
335 | ps->snap->chunk_shift = ffs(chunk_size) - 1; | |
336 | ||
6cca1e7a HM |
337 | r = dm_io_client_resize(sectors_to_pages(ps->snap->chunk_size), |
338 | ps->io_client); | |
4c7e3bf4 MM |
339 | if (r) |
340 | return r; | |
341 | ||
342 | r = alloc_area(ps); | |
6cca1e7a | 343 | return r; |
4c7e3bf4 | 344 | |
6cca1e7a | 345 | bad: |
4c7e3bf4 | 346 | free_area(ps); |
1da177e4 LT |
347 | return r; |
348 | } | |
349 | ||
350 | static int write_header(struct pstore *ps) | |
351 | { | |
352 | struct disk_header *dh; | |
353 | ||
c51c2752 | 354 | memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT); |
1da177e4 LT |
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); | |
c51c2752 | 360 | dh->chunk_size = cpu_to_le32(ps->snap->chunk_size); |
1da177e4 | 361 | |
fcac03ab | 362 | return chunk_io(ps, 0, WRITE, 1); |
1da177e4 LT |
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 | { | |
e4ff496d | 370 | BUG_ON(index >= ps->exceptions_per_area); |
1da177e4 LT |
371 | |
372 | return ((struct disk_exception *) ps->area) + index; | |
373 | } | |
374 | ||
e4ff496d MM |
375 | static void read_exception(struct pstore *ps, |
376 | uint32_t index, struct disk_exception *result) | |
1da177e4 | 377 | { |
e4ff496d | 378 | struct disk_exception *e = get_exception(ps, index); |
1da177e4 LT |
379 | |
380 | /* copy it */ | |
381 | result->old_chunk = le64_to_cpu(e->old_chunk); | |
382 | result->new_chunk = le64_to_cpu(e->new_chunk); | |
1da177e4 LT |
383 | } |
384 | ||
e4ff496d MM |
385 | static void write_exception(struct pstore *ps, |
386 | uint32_t index, struct disk_exception *de) | |
1da177e4 | 387 | { |
e4ff496d | 388 | struct disk_exception *e = get_exception(ps, index); |
1da177e4 LT |
389 | |
390 | /* copy it */ | |
391 | e->old_chunk = cpu_to_le64(de->old_chunk); | |
392 | e->new_chunk = cpu_to_le64(de->new_chunk); | |
1da177e4 LT |
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 | */ | |
400 | static int insert_exceptions(struct pstore *ps, int *full) | |
401 | { | |
402 | int r; | |
403 | unsigned int i; | |
404 | struct disk_exception de; | |
405 | ||
406 | /* presume the area is full */ | |
407 | *full = 1; | |
408 | ||
409 | for (i = 0; i < ps->exceptions_per_area; i++) { | |
e4ff496d | 410 | read_exception(ps, i, &de); |
1da177e4 LT |
411 | |
412 | /* | |
413 | * If the new_chunk is pointing at the start of | |
414 | * the COW device, where the first metadata area | |
415 | * is we know that we've hit the end of the | |
416 | * exceptions. Therefore the area is not full. | |
417 | */ | |
418 | if (de.new_chunk == 0LL) { | |
419 | ps->current_committed = i; | |
420 | *full = 0; | |
421 | break; | |
422 | } | |
423 | ||
424 | /* | |
425 | * Keep track of the start of the free chunks. | |
426 | */ | |
427 | if (ps->next_free <= de.new_chunk) | |
428 | ps->next_free = de.new_chunk + 1; | |
429 | ||
430 | /* | |
431 | * Otherwise we add the exception to the snapshot. | |
432 | */ | |
433 | r = dm_add_exception(ps->snap, de.old_chunk, de.new_chunk); | |
434 | if (r) | |
435 | return r; | |
436 | } | |
437 | ||
438 | return 0; | |
439 | } | |
440 | ||
441 | static int read_exceptions(struct pstore *ps) | |
442 | { | |
1da177e4 LT |
443 | int r, full = 1; |
444 | ||
445 | /* | |
446 | * Keeping reading chunks and inserting exceptions until | |
447 | * we find a partially full area. | |
448 | */ | |
7c9e6c17 AK |
449 | for (ps->current_area = 0; full; ps->current_area++) { |
450 | r = area_io(ps, READ); | |
1da177e4 LT |
451 | if (r) |
452 | return r; | |
453 | ||
454 | r = insert_exceptions(ps, &full); | |
455 | if (r) | |
456 | return r; | |
457 | } | |
458 | ||
7c9e6c17 AK |
459 | ps->current_area--; |
460 | ||
1da177e4 LT |
461 | return 0; |
462 | } | |
463 | ||
028867ac | 464 | static struct pstore *get_info(struct exception_store *store) |
1da177e4 LT |
465 | { |
466 | return (struct pstore *) store->context; | |
467 | } | |
468 | ||
469 | static void persistent_fraction_full(struct exception_store *store, | |
470 | sector_t *numerator, sector_t *denominator) | |
471 | { | |
472 | *numerator = get_info(store)->next_free * store->snap->chunk_size; | |
473 | *denominator = get_dev_size(store->snap->cow->bdev); | |
474 | } | |
475 | ||
476 | static void persistent_destroy(struct exception_store *store) | |
477 | { | |
478 | struct pstore *ps = get_info(store); | |
479 | ||
fcac03ab | 480 | destroy_workqueue(ps->metadata_wq); |
6cca1e7a | 481 | dm_io_client_destroy(ps->io_client); |
1da177e4 LT |
482 | vfree(ps->callbacks); |
483 | free_area(ps); | |
484 | kfree(ps); | |
485 | } | |
486 | ||
487 | static int persistent_read_metadata(struct exception_store *store) | |
488 | { | |
e48b9db2 | 489 | int r, uninitialized_var(new_snapshot); |
1da177e4 LT |
490 | struct pstore *ps = get_info(store); |
491 | ||
492 | /* | |
493 | * Read the snapshot header. | |
494 | */ | |
495 | r = read_header(ps, &new_snapshot); | |
496 | if (r) | |
497 | return r; | |
498 | ||
c51c2752 AK |
499 | /* |
500 | * Now we know correct chunk_size, complete the initialisation. | |
501 | */ | |
502 | ps->exceptions_per_area = (ps->snap->chunk_size << SECTOR_SHIFT) / | |
503 | sizeof(struct disk_exception); | |
504 | ps->callbacks = dm_vcalloc(ps->exceptions_per_area, | |
505 | sizeof(*ps->callbacks)); | |
506 | if (!ps->callbacks) | |
507 | return -ENOMEM; | |
508 | ||
1da177e4 LT |
509 | /* |
510 | * Do we need to setup a new snapshot ? | |
511 | */ | |
512 | if (new_snapshot) { | |
513 | r = write_header(ps); | |
514 | if (r) { | |
515 | DMWARN("write_header failed"); | |
516 | return r; | |
517 | } | |
518 | ||
7c9e6c17 AK |
519 | ps->current_area = 0; |
520 | zero_memory_area(ps); | |
521 | r = zero_disk_area(ps, 0); | |
1da177e4 | 522 | if (r) { |
7c9e6c17 | 523 | DMWARN("zero_disk_area(0) failed"); |
1da177e4 LT |
524 | return r; |
525 | } | |
1da177e4 LT |
526 | } else { |
527 | /* | |
528 | * Sanity checks. | |
529 | */ | |
1da177e4 LT |
530 | if (ps->version != SNAPSHOT_DISK_VERSION) { |
531 | DMWARN("unable to handle snapshot disk version %d", | |
532 | ps->version); | |
533 | return -EINVAL; | |
534 | } | |
535 | ||
0764147b MB |
536 | /* |
537 | * Metadata are valid, but snapshot is invalidated | |
538 | */ | |
539 | if (!ps->valid) | |
540 | return 1; | |
541 | ||
1da177e4 LT |
542 | /* |
543 | * Read the metadata. | |
544 | */ | |
545 | r = read_exceptions(ps); | |
546 | if (r) | |
547 | return r; | |
548 | } | |
549 | ||
550 | return 0; | |
551 | } | |
552 | ||
553 | static int persistent_prepare(struct exception_store *store, | |
028867ac | 554 | struct dm_snap_exception *e) |
1da177e4 LT |
555 | { |
556 | struct pstore *ps = get_info(store); | |
557 | uint32_t stride; | |
fd14acf6 | 558 | chunk_t next_free; |
1da177e4 LT |
559 | sector_t size = get_dev_size(store->snap->cow->bdev); |
560 | ||
561 | /* Is there enough room ? */ | |
562 | if (size < ((ps->next_free + 1) * store->snap->chunk_size)) | |
563 | return -ENOSPC; | |
564 | ||
565 | e->new_chunk = ps->next_free; | |
566 | ||
567 | /* | |
568 | * Move onto the next free pending, making sure to take | |
569 | * into account the location of the metadata chunks. | |
570 | */ | |
571 | stride = (ps->exceptions_per_area + 1); | |
fd14acf6 MP |
572 | next_free = ++ps->next_free; |
573 | if (sector_div(next_free, stride) == 1) | |
1da177e4 LT |
574 | ps->next_free++; |
575 | ||
576 | atomic_inc(&ps->pending_count); | |
577 | return 0; | |
578 | } | |
579 | ||
580 | static void persistent_commit(struct exception_store *store, | |
028867ac | 581 | struct dm_snap_exception *e, |
1da177e4 LT |
582 | void (*callback) (void *, int success), |
583 | void *callback_context) | |
584 | { | |
1da177e4 LT |
585 | unsigned int i; |
586 | struct pstore *ps = get_info(store); | |
587 | struct disk_exception de; | |
588 | struct commit_callback *cb; | |
589 | ||
590 | de.old_chunk = e->old_chunk; | |
591 | de.new_chunk = e->new_chunk; | |
592 | write_exception(ps, ps->current_committed++, &de); | |
593 | ||
594 | /* | |
595 | * Add the callback to the back of the array. This code | |
596 | * is the only place where the callback array is | |
597 | * manipulated, and we know that it will never be called | |
598 | * multiple times concurrently. | |
599 | */ | |
600 | cb = ps->callbacks + ps->callback_count++; | |
601 | cb->callback = callback; | |
602 | cb->context = callback_context; | |
603 | ||
604 | /* | |
7c9e6c17 AK |
605 | * If there are exceptions in flight and we have not yet |
606 | * filled this metadata area there's nothing more to do. | |
1da177e4 | 607 | */ |
7c9e6c17 AK |
608 | if (!atomic_dec_and_test(&ps->pending_count) && |
609 | (ps->current_committed != ps->exceptions_per_area)) | |
610 | return; | |
1da177e4 | 611 | |
7acedc5b MP |
612 | /* |
613 | * If we completely filled the current area, then wipe the next one. | |
614 | */ | |
615 | if ((ps->current_committed == ps->exceptions_per_area) && | |
616 | zero_disk_area(ps, ps->current_area + 1)) | |
617 | ps->valid = 0; | |
618 | ||
7c9e6c17 AK |
619 | /* |
620 | * Commit exceptions to disk. | |
621 | */ | |
7acedc5b | 622 | if (ps->valid && area_io(ps, WRITE)) |
7c9e6c17 | 623 | ps->valid = 0; |
927ffe7c | 624 | |
7c9e6c17 AK |
625 | /* |
626 | * Advance to the next area if this one is full. | |
627 | */ | |
628 | if (ps->current_committed == ps->exceptions_per_area) { | |
7c9e6c17 AK |
629 | ps->current_committed = 0; |
630 | ps->current_area++; | |
631 | zero_memory_area(ps); | |
632 | } | |
1da177e4 | 633 | |
7c9e6c17 AK |
634 | for (i = 0; i < ps->callback_count; i++) { |
635 | cb = ps->callbacks + i; | |
636 | cb->callback(cb->context, ps->valid); | |
1da177e4 | 637 | } |
7c9e6c17 AK |
638 | |
639 | ps->callback_count = 0; | |
1da177e4 LT |
640 | } |
641 | ||
642 | static void persistent_drop(struct exception_store *store) | |
643 | { | |
644 | struct pstore *ps = get_info(store); | |
645 | ||
646 | ps->valid = 0; | |
647 | if (write_header(ps)) | |
648 | DMWARN("write header failed"); | |
649 | } | |
650 | ||
4c7e3bf4 | 651 | int dm_create_persistent(struct exception_store *store) |
1da177e4 | 652 | { |
1da177e4 LT |
653 | struct pstore *ps; |
654 | ||
1da177e4 LT |
655 | /* allocate the pstore */ |
656 | ps = kmalloc(sizeof(*ps), GFP_KERNEL); | |
4c7e3bf4 MM |
657 | if (!ps) |
658 | return -ENOMEM; | |
1da177e4 LT |
659 | |
660 | ps->snap = store->snap; | |
661 | ps->valid = 1; | |
662 | ps->version = SNAPSHOT_DISK_VERSION; | |
4c7e3bf4 | 663 | ps->area = NULL; |
1da177e4 LT |
664 | ps->next_free = 2; /* skipping the header and first area */ |
665 | ps->current_committed = 0; | |
666 | ||
1da177e4 LT |
667 | ps->callback_count = 0; |
668 | atomic_set(&ps->pending_count, 0); | |
c51c2752 | 669 | ps->callbacks = NULL; |
1da177e4 | 670 | |
fcac03ab MB |
671 | ps->metadata_wq = create_singlethread_workqueue("ksnaphd"); |
672 | if (!ps->metadata_wq) { | |
851a8a7f | 673 | kfree(ps); |
fcac03ab MB |
674 | DMERR("couldn't start header metadata update thread"); |
675 | return -ENOMEM; | |
676 | } | |
677 | ||
1da177e4 LT |
678 | store->destroy = persistent_destroy; |
679 | store->read_metadata = persistent_read_metadata; | |
680 | store->prepare_exception = persistent_prepare; | |
681 | store->commit_exception = persistent_commit; | |
682 | store->drop_snapshot = persistent_drop; | |
683 | store->fraction_full = persistent_fraction_full; | |
684 | store->context = ps; | |
685 | ||
686 | return 0; | |
1da177e4 LT |
687 | } |
688 | ||
689 | /*----------------------------------------------------------------- | |
690 | * Implementation of the store for non-persistent snapshots. | |
691 | *---------------------------------------------------------------*/ | |
692 | struct transient_c { | |
693 | sector_t next_free; | |
694 | }; | |
695 | ||
696 | static void transient_destroy(struct exception_store *store) | |
697 | { | |
698 | kfree(store->context); | |
699 | } | |
700 | ||
701 | static int transient_read_metadata(struct exception_store *store) | |
702 | { | |
703 | return 0; | |
704 | } | |
705 | ||
028867ac AK |
706 | static int transient_prepare(struct exception_store *store, |
707 | struct dm_snap_exception *e) | |
1da177e4 LT |
708 | { |
709 | struct transient_c *tc = (struct transient_c *) store->context; | |
710 | sector_t size = get_dev_size(store->snap->cow->bdev); | |
711 | ||
712 | if (size < (tc->next_free + store->snap->chunk_size)) | |
713 | return -1; | |
714 | ||
715 | e->new_chunk = sector_to_chunk(store->snap, tc->next_free); | |
716 | tc->next_free += store->snap->chunk_size; | |
717 | ||
718 | return 0; | |
719 | } | |
720 | ||
721 | static void transient_commit(struct exception_store *store, | |
028867ac AK |
722 | struct dm_snap_exception *e, |
723 | void (*callback) (void *, int success), | |
724 | void *callback_context) | |
1da177e4 LT |
725 | { |
726 | /* Just succeed */ | |
727 | callback(callback_context, 1); | |
728 | } | |
729 | ||
730 | static void transient_fraction_full(struct exception_store *store, | |
731 | sector_t *numerator, sector_t *denominator) | |
732 | { | |
733 | *numerator = ((struct transient_c *) store->context)->next_free; | |
734 | *denominator = get_dev_size(store->snap->cow->bdev); | |
735 | } | |
736 | ||
4c7e3bf4 | 737 | int dm_create_transient(struct exception_store *store) |
1da177e4 LT |
738 | { |
739 | struct transient_c *tc; | |
740 | ||
1da177e4 LT |
741 | store->destroy = transient_destroy; |
742 | store->read_metadata = transient_read_metadata; | |
743 | store->prepare_exception = transient_prepare; | |
744 | store->commit_exception = transient_commit; | |
4c7e3bf4 | 745 | store->drop_snapshot = NULL; |
1da177e4 | 746 | store->fraction_full = transient_fraction_full; |
1da177e4 LT |
747 | |
748 | tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL); | |
749 | if (!tc) | |
750 | return -ENOMEM; | |
751 | ||
752 | tc->next_free = 0; | |
753 | store->context = tc; | |
754 | ||
755 | return 0; | |
756 | } |