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 | ||
10 | #include "dm.h" | |
11 | #include "dm-snap.h" | |
1da177e4 LT |
12 | |
13 | #include <linux/mm.h> | |
14 | #include <linux/pagemap.h> | |
15 | #include <linux/vmalloc.h> | |
16 | #include <linux/slab.h> | |
a765e20e AK |
17 | #include <linux/dm-io.h> |
18 | #include <linux/dm-kcopyd.h> | |
1da177e4 | 19 | |
72d94861 | 20 | #define DM_MSG_PREFIX "snapshots" |
4c7e3bf4 | 21 | #define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */ |
72d94861 | 22 | |
1da177e4 LT |
23 | /*----------------------------------------------------------------- |
24 | * Persistent snapshots, by persistent we mean that the snapshot | |
25 | * will survive a reboot. | |
26 | *---------------------------------------------------------------*/ | |
27 | ||
28 | /* | |
29 | * We need to store a record of which parts of the origin have | |
30 | * been copied to the snapshot device. The snapshot code | |
31 | * requires that we copy exception chunks to chunk aligned areas | |
32 | * of the COW store. It makes sense therefore, to store the | |
33 | * metadata in chunk size blocks. | |
34 | * | |
35 | * There is no backward or forward compatibility implemented, | |
36 | * snapshots with different disk versions than the kernel will | |
37 | * not be usable. It is expected that "lvcreate" will blank out | |
38 | * the start of a fresh COW device before calling the snapshot | |
39 | * constructor. | |
40 | * | |
41 | * The first chunk of the COW device just contains the header. | |
42 | * After this there is a chunk filled with exception metadata, | |
43 | * followed by as many exception chunks as can fit in the | |
44 | * metadata areas. | |
45 | * | |
46 | * All on disk structures are in little-endian format. The end | |
47 | * of the exceptions info is indicated by an exception with a | |
48 | * new_chunk of 0, which is invalid since it would point to the | |
49 | * header chunk. | |
50 | */ | |
51 | ||
52 | /* | |
53 | * Magic for persistent snapshots: "SnAp" - Feeble isn't it. | |
54 | */ | |
55 | #define SNAP_MAGIC 0x70416e53 | |
56 | ||
57 | /* | |
58 | * The on-disk version of the metadata. | |
59 | */ | |
60 | #define SNAPSHOT_DISK_VERSION 1 | |
61 | ||
62 | struct disk_header { | |
63 | uint32_t magic; | |
64 | ||
65 | /* | |
66 | * Is this snapshot valid. There is no way of recovering | |
67 | * an invalid snapshot. | |
68 | */ | |
69 | uint32_t valid; | |
70 | ||
71 | /* | |
72 | * Simple, incrementing version. no backward | |
73 | * compatibility. | |
74 | */ | |
75 | uint32_t version; | |
76 | ||
77 | /* In sectors */ | |
78 | uint32_t chunk_size; | |
79 | }; | |
80 | ||
81 | struct disk_exception { | |
82 | uint64_t old_chunk; | |
83 | uint64_t new_chunk; | |
84 | }; | |
85 | ||
86 | struct commit_callback { | |
87 | void (*callback)(void *, int success); | |
88 | void *context; | |
89 | }; | |
90 | ||
91 | /* | |
92 | * The top level structure for a persistent exception store. | |
93 | */ | |
94 | struct pstore { | |
95 | struct dm_snapshot *snap; /* up pointer to my snapshot */ | |
96 | int version; | |
97 | int valid; | |
1da177e4 LT |
98 | uint32_t exceptions_per_area; |
99 | ||
100 | /* | |
101 | * Now that we have an asynchronous kcopyd there is no | |
102 | * need for large chunk sizes, so it wont hurt to have a | |
103 | * whole chunks worth of metadata in memory at once. | |
104 | */ | |
105 | void *area; | |
106 | ||
7c9e6c17 AK |
107 | /* |
108 | * An area of zeros used to clear the next area. | |
109 | */ | |
110 | void *zero_area; | |
111 | ||
1da177e4 LT |
112 | /* |
113 | * Used to keep track of which metadata area the data in | |
114 | * 'chunk' refers to. | |
115 | */ | |
fd14acf6 | 116 | chunk_t current_area; |
1da177e4 LT |
117 | |
118 | /* | |
119 | * The next free chunk for an exception. | |
120 | */ | |
fd14acf6 | 121 | chunk_t next_free; |
1da177e4 LT |
122 | |
123 | /* | |
124 | * The index of next free exception in the current | |
125 | * metadata area. | |
126 | */ | |
127 | uint32_t current_committed; | |
128 | ||
129 | atomic_t pending_count; | |
130 | uint32_t callback_count; | |
131 | struct commit_callback *callbacks; | |
6cca1e7a | 132 | struct dm_io_client *io_client; |
fcac03ab MB |
133 | |
134 | struct workqueue_struct *metadata_wq; | |
1da177e4 LT |
135 | }; |
136 | ||
028867ac | 137 | static unsigned sectors_to_pages(unsigned sectors) |
1da177e4 | 138 | { |
92436262 | 139 | return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9); |
1da177e4 LT |
140 | } |
141 | ||
142 | static int alloc_area(struct pstore *ps) | |
143 | { | |
144 | int r = -ENOMEM; | |
145 | size_t len; | |
146 | ||
c51c2752 | 147 | len = ps->snap->chunk_size << SECTOR_SHIFT; |
1da177e4 LT |
148 | |
149 | /* | |
150 | * Allocate the chunk_size block of memory that will hold | |
151 | * a single metadata area. | |
152 | */ | |
153 | ps->area = vmalloc(len); | |
154 | if (!ps->area) | |
155 | return r; | |
156 | ||
7c9e6c17 AK |
157 | ps->zero_area = vmalloc(len); |
158 | if (!ps->zero_area) { | |
159 | vfree(ps->area); | |
160 | return r; | |
161 | } | |
162 | memset(ps->zero_area, 0, len); | |
163 | ||
1da177e4 LT |
164 | return 0; |
165 | } | |
166 | ||
167 | static void free_area(struct pstore *ps) | |
168 | { | |
169 | vfree(ps->area); | |
4c7e3bf4 | 170 | ps->area = NULL; |
7c9e6c17 AK |
171 | vfree(ps->zero_area); |
172 | ps->zero_area = NULL; | |
1da177e4 LT |
173 | } |
174 | ||
fcac03ab | 175 | struct mdata_req { |
22a1ceb1 | 176 | struct dm_io_region *where; |
fcac03ab MB |
177 | struct dm_io_request *io_req; |
178 | struct work_struct work; | |
179 | int result; | |
180 | }; | |
181 | ||
182 | static void do_metadata(struct work_struct *work) | |
183 | { | |
184 | struct mdata_req *req = container_of(work, struct mdata_req, work); | |
185 | ||
186 | req->result = dm_io(req->io_req, 1, req->where, NULL); | |
187 | } | |
188 | ||
1da177e4 LT |
189 | /* |
190 | * Read or write a chunk aligned and sized block of data from a device. | |
191 | */ | |
fd14acf6 | 192 | static int chunk_io(struct pstore *ps, chunk_t chunk, int rw, int metadata) |
1da177e4 | 193 | { |
22a1ceb1 | 194 | struct dm_io_region where = { |
6cca1e7a HM |
195 | .bdev = ps->snap->cow->bdev, |
196 | .sector = ps->snap->chunk_size * chunk, | |
197 | .count = ps->snap->chunk_size, | |
198 | }; | |
199 | struct dm_io_request io_req = { | |
200 | .bi_rw = rw, | |
201 | .mem.type = DM_IO_VMA, | |
202 | .mem.ptr.vma = ps->area, | |
203 | .client = ps->io_client, | |
204 | .notify.fn = NULL, | |
205 | }; | |
fcac03ab MB |
206 | struct mdata_req req; |
207 | ||
208 | if (!metadata) | |
209 | return dm_io(&io_req, 1, &where, NULL); | |
6cca1e7a | 210 | |
fcac03ab MB |
211 | req.where = &where; |
212 | req.io_req = &io_req; | |
213 | ||
214 | /* | |
215 | * Issue the synchronous I/O from a different thread | |
216 | * to avoid generic_make_request recursion. | |
217 | */ | |
218 | INIT_WORK(&req.work, do_metadata); | |
219 | queue_work(ps->metadata_wq, &req.work); | |
220 | flush_workqueue(ps->metadata_wq); | |
221 | ||
222 | return req.result; | |
1da177e4 LT |
223 | } |
224 | ||
a481db78 MP |
225 | /* |
226 | * Convert a metadata area index to a chunk index. | |
227 | */ | |
228 | static chunk_t area_location(struct pstore *ps, chunk_t area) | |
229 | { | |
230 | return 1 + ((ps->exceptions_per_area + 1) * area); | |
231 | } | |
232 | ||
1da177e4 LT |
233 | /* |
234 | * Read or write a metadata area. Remembering to skip the first | |
235 | * chunk which holds the header. | |
236 | */ | |
7c9e6c17 | 237 | static int area_io(struct pstore *ps, int rw) |
1da177e4 LT |
238 | { |
239 | int r; | |
fd14acf6 | 240 | chunk_t chunk; |
1da177e4 | 241 | |
7c9e6c17 | 242 | chunk = area_location(ps, ps->current_area); |
1da177e4 | 243 | |
fcac03ab | 244 | r = chunk_io(ps, chunk, rw, 0); |
1da177e4 LT |
245 | if (r) |
246 | return r; | |
247 | ||
1da177e4 LT |
248 | return 0; |
249 | } | |
250 | ||
7c9e6c17 | 251 | static void zero_memory_area(struct pstore *ps) |
1da177e4 | 252 | { |
c51c2752 | 253 | memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT); |
7c9e6c17 AK |
254 | } |
255 | ||
256 | static int zero_disk_area(struct pstore *ps, chunk_t area) | |
257 | { | |
258 | struct dm_io_region where = { | |
259 | .bdev = ps->snap->cow->bdev, | |
260 | .sector = ps->snap->chunk_size * area_location(ps, area), | |
261 | .count = ps->snap->chunk_size, | |
262 | }; | |
263 | struct dm_io_request io_req = { | |
264 | .bi_rw = WRITE, | |
265 | .mem.type = DM_IO_VMA, | |
266 | .mem.ptr.vma = ps->zero_area, | |
267 | .client = ps->io_client, | |
268 | .notify.fn = NULL, | |
269 | }; | |
270 | ||
271 | return dm_io(&io_req, 1, &where, NULL); | |
1da177e4 LT |
272 | } |
273 | ||
274 | static int read_header(struct pstore *ps, int *new_snapshot) | |
275 | { | |
276 | int r; | |
277 | struct disk_header *dh; | |
c51c2752 | 278 | chunk_t chunk_size; |
4c7e3bf4 | 279 | int chunk_size_supplied = 1; |
1da177e4 | 280 | |
4c7e3bf4 MM |
281 | /* |
282 | * Use default chunk size (or hardsect_size, if larger) if none supplied | |
283 | */ | |
284 | if (!ps->snap->chunk_size) { | |
285 | ps->snap->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS, | |
286 | bdev_hardsect_size(ps->snap->cow->bdev) >> 9); | |
287 | ps->snap->chunk_mask = ps->snap->chunk_size - 1; | |
288 | ps->snap->chunk_shift = ffs(ps->snap->chunk_size) - 1; | |
289 | chunk_size_supplied = 0; | |
290 | } | |
291 | ||
6cca1e7a HM |
292 | ps->io_client = dm_io_client_create(sectors_to_pages(ps->snap-> |
293 | chunk_size)); | |
294 | if (IS_ERR(ps->io_client)) | |
295 | return PTR_ERR(ps->io_client); | |
1da177e4 | 296 | |
4c7e3bf4 MM |
297 | r = alloc_area(ps); |
298 | if (r) | |
6cca1e7a | 299 | return r; |
4c7e3bf4 | 300 | |
fcac03ab | 301 | r = chunk_io(ps, 0, READ, 1); |
4c7e3bf4 | 302 | if (r) |
6cca1e7a | 303 | goto bad; |
4c7e3bf4 | 304 | |
1da177e4 LT |
305 | dh = (struct disk_header *) ps->area; |
306 | ||
307 | if (le32_to_cpu(dh->magic) == 0) { | |
308 | *new_snapshot = 1; | |
4c7e3bf4 MM |
309 | return 0; |
310 | } | |
1da177e4 | 311 | |
4c7e3bf4 MM |
312 | if (le32_to_cpu(dh->magic) != SNAP_MAGIC) { |
313 | DMWARN("Invalid or corrupt snapshot"); | |
1da177e4 | 314 | r = -ENXIO; |
6cca1e7a | 315 | goto bad; |
1da177e4 LT |
316 | } |
317 | ||
4c7e3bf4 MM |
318 | *new_snapshot = 0; |
319 | ps->valid = le32_to_cpu(dh->valid); | |
320 | ps->version = le32_to_cpu(dh->version); | |
321 | chunk_size = le32_to_cpu(dh->chunk_size); | |
322 | ||
323 | if (!chunk_size_supplied || ps->snap->chunk_size == chunk_size) | |
324 | return 0; | |
325 | ||
326 | DMWARN("chunk size %llu in device metadata overrides " | |
327 | "table chunk size of %llu.", | |
328 | (unsigned long long)chunk_size, | |
329 | (unsigned long long)ps->snap->chunk_size); | |
330 | ||
331 | /* We had a bogus chunk_size. Fix stuff up. */ | |
4c7e3bf4 MM |
332 | free_area(ps); |
333 | ||
334 | ps->snap->chunk_size = chunk_size; | |
335 | ps->snap->chunk_mask = chunk_size - 1; | |
336 | ps->snap->chunk_shift = ffs(chunk_size) - 1; | |
337 | ||
6cca1e7a HM |
338 | r = dm_io_client_resize(sectors_to_pages(ps->snap->chunk_size), |
339 | ps->io_client); | |
4c7e3bf4 MM |
340 | if (r) |
341 | return r; | |
342 | ||
343 | r = alloc_area(ps); | |
6cca1e7a | 344 | return r; |
4c7e3bf4 | 345 | |
6cca1e7a | 346 | bad: |
4c7e3bf4 | 347 | free_area(ps); |
1da177e4 LT |
348 | return r; |
349 | } | |
350 | ||
351 | static int write_header(struct pstore *ps) | |
352 | { | |
353 | struct disk_header *dh; | |
354 | ||
c51c2752 | 355 | memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT); |
1da177e4 LT |
356 | |
357 | dh = (struct disk_header *) ps->area; | |
358 | dh->magic = cpu_to_le32(SNAP_MAGIC); | |
359 | dh->valid = cpu_to_le32(ps->valid); | |
360 | dh->version = cpu_to_le32(ps->version); | |
c51c2752 | 361 | dh->chunk_size = cpu_to_le32(ps->snap->chunk_size); |
1da177e4 | 362 | |
fcac03ab | 363 | return chunk_io(ps, 0, WRITE, 1); |
1da177e4 LT |
364 | } |
365 | ||
366 | /* | |
367 | * Access functions for the disk exceptions, these do the endian conversions. | |
368 | */ | |
369 | static struct disk_exception *get_exception(struct pstore *ps, uint32_t index) | |
370 | { | |
e4ff496d | 371 | BUG_ON(index >= ps->exceptions_per_area); |
1da177e4 LT |
372 | |
373 | return ((struct disk_exception *) ps->area) + index; | |
374 | } | |
375 | ||
e4ff496d MM |
376 | static void read_exception(struct pstore *ps, |
377 | uint32_t index, struct disk_exception *result) | |
1da177e4 | 378 | { |
e4ff496d | 379 | struct disk_exception *e = get_exception(ps, index); |
1da177e4 LT |
380 | |
381 | /* copy it */ | |
382 | result->old_chunk = le64_to_cpu(e->old_chunk); | |
383 | result->new_chunk = le64_to_cpu(e->new_chunk); | |
1da177e4 LT |
384 | } |
385 | ||
e4ff496d MM |
386 | static void write_exception(struct pstore *ps, |
387 | uint32_t index, struct disk_exception *de) | |
1da177e4 | 388 | { |
e4ff496d | 389 | struct disk_exception *e = get_exception(ps, index); |
1da177e4 LT |
390 | |
391 | /* copy it */ | |
392 | e->old_chunk = cpu_to_le64(de->old_chunk); | |
393 | e->new_chunk = cpu_to_le64(de->new_chunk); | |
1da177e4 LT |
394 | } |
395 | ||
396 | /* | |
397 | * Registers the exceptions that are present in the current area. | |
398 | * 'full' is filled in to indicate if the area has been | |
399 | * filled. | |
400 | */ | |
401 | static int insert_exceptions(struct pstore *ps, int *full) | |
402 | { | |
403 | int r; | |
404 | unsigned int i; | |
405 | struct disk_exception de; | |
406 | ||
407 | /* presume the area is full */ | |
408 | *full = 1; | |
409 | ||
410 | for (i = 0; i < ps->exceptions_per_area; i++) { | |
e4ff496d | 411 | read_exception(ps, i, &de); |
1da177e4 LT |
412 | |
413 | /* | |
414 | * If the new_chunk is pointing at the start of | |
415 | * the COW device, where the first metadata area | |
416 | * is we know that we've hit the end of the | |
417 | * exceptions. Therefore the area is not full. | |
418 | */ | |
419 | if (de.new_chunk == 0LL) { | |
420 | ps->current_committed = i; | |
421 | *full = 0; | |
422 | break; | |
423 | } | |
424 | ||
425 | /* | |
426 | * Keep track of the start of the free chunks. | |
427 | */ | |
428 | if (ps->next_free <= de.new_chunk) | |
429 | ps->next_free = de.new_chunk + 1; | |
430 | ||
431 | /* | |
432 | * Otherwise we add the exception to the snapshot. | |
433 | */ | |
434 | r = dm_add_exception(ps->snap, de.old_chunk, de.new_chunk); | |
435 | if (r) | |
436 | return r; | |
437 | } | |
438 | ||
439 | return 0; | |
440 | } | |
441 | ||
442 | static int read_exceptions(struct pstore *ps) | |
443 | { | |
1da177e4 LT |
444 | int r, full = 1; |
445 | ||
446 | /* | |
447 | * Keeping reading chunks and inserting exceptions until | |
448 | * we find a partially full area. | |
449 | */ | |
7c9e6c17 AK |
450 | for (ps->current_area = 0; full; ps->current_area++) { |
451 | r = area_io(ps, READ); | |
1da177e4 LT |
452 | if (r) |
453 | return r; | |
454 | ||
455 | r = insert_exceptions(ps, &full); | |
456 | if (r) | |
457 | return r; | |
458 | } | |
459 | ||
7c9e6c17 AK |
460 | ps->current_area--; |
461 | ||
1da177e4 LT |
462 | return 0; |
463 | } | |
464 | ||
028867ac | 465 | static struct pstore *get_info(struct exception_store *store) |
1da177e4 LT |
466 | { |
467 | return (struct pstore *) store->context; | |
468 | } | |
469 | ||
470 | static void persistent_fraction_full(struct exception_store *store, | |
471 | sector_t *numerator, sector_t *denominator) | |
472 | { | |
473 | *numerator = get_info(store)->next_free * store->snap->chunk_size; | |
474 | *denominator = get_dev_size(store->snap->cow->bdev); | |
475 | } | |
476 | ||
477 | static void persistent_destroy(struct exception_store *store) | |
478 | { | |
479 | struct pstore *ps = get_info(store); | |
480 | ||
fcac03ab | 481 | destroy_workqueue(ps->metadata_wq); |
6cca1e7a | 482 | dm_io_client_destroy(ps->io_client); |
1da177e4 LT |
483 | vfree(ps->callbacks); |
484 | free_area(ps); | |
485 | kfree(ps); | |
486 | } | |
487 | ||
488 | static int persistent_read_metadata(struct exception_store *store) | |
489 | { | |
e48b9db2 | 490 | int r, uninitialized_var(new_snapshot); |
1da177e4 LT |
491 | struct pstore *ps = get_info(store); |
492 | ||
493 | /* | |
494 | * Read the snapshot header. | |
495 | */ | |
496 | r = read_header(ps, &new_snapshot); | |
497 | if (r) | |
498 | return r; | |
499 | ||
c51c2752 AK |
500 | /* |
501 | * Now we know correct chunk_size, complete the initialisation. | |
502 | */ | |
503 | ps->exceptions_per_area = (ps->snap->chunk_size << SECTOR_SHIFT) / | |
504 | sizeof(struct disk_exception); | |
505 | ps->callbacks = dm_vcalloc(ps->exceptions_per_area, | |
506 | sizeof(*ps->callbacks)); | |
507 | if (!ps->callbacks) | |
508 | return -ENOMEM; | |
509 | ||
1da177e4 LT |
510 | /* |
511 | * Do we need to setup a new snapshot ? | |
512 | */ | |
513 | if (new_snapshot) { | |
514 | r = write_header(ps); | |
515 | if (r) { | |
516 | DMWARN("write_header failed"); | |
517 | return r; | |
518 | } | |
519 | ||
7c9e6c17 AK |
520 | ps->current_area = 0; |
521 | zero_memory_area(ps); | |
522 | r = zero_disk_area(ps, 0); | |
1da177e4 | 523 | if (r) { |
7c9e6c17 | 524 | DMWARN("zero_disk_area(0) failed"); |
1da177e4 LT |
525 | return r; |
526 | } | |
1da177e4 LT |
527 | } else { |
528 | /* | |
529 | * Sanity checks. | |
530 | */ | |
1da177e4 LT |
531 | if (ps->version != SNAPSHOT_DISK_VERSION) { |
532 | DMWARN("unable to handle snapshot disk version %d", | |
533 | ps->version); | |
534 | return -EINVAL; | |
535 | } | |
536 | ||
0764147b MB |
537 | /* |
538 | * Metadata are valid, but snapshot is invalidated | |
539 | */ | |
540 | if (!ps->valid) | |
541 | return 1; | |
542 | ||
1da177e4 LT |
543 | /* |
544 | * Read the metadata. | |
545 | */ | |
546 | r = read_exceptions(ps); | |
547 | if (r) | |
548 | return r; | |
549 | } | |
550 | ||
551 | return 0; | |
552 | } | |
553 | ||
554 | static int persistent_prepare(struct exception_store *store, | |
028867ac | 555 | struct dm_snap_exception *e) |
1da177e4 LT |
556 | { |
557 | struct pstore *ps = get_info(store); | |
558 | uint32_t stride; | |
fd14acf6 | 559 | chunk_t next_free; |
1da177e4 LT |
560 | sector_t size = get_dev_size(store->snap->cow->bdev); |
561 | ||
562 | /* Is there enough room ? */ | |
563 | if (size < ((ps->next_free + 1) * store->snap->chunk_size)) | |
564 | return -ENOSPC; | |
565 | ||
566 | e->new_chunk = ps->next_free; | |
567 | ||
568 | /* | |
569 | * Move onto the next free pending, making sure to take | |
570 | * into account the location of the metadata chunks. | |
571 | */ | |
572 | stride = (ps->exceptions_per_area + 1); | |
fd14acf6 MP |
573 | next_free = ++ps->next_free; |
574 | if (sector_div(next_free, stride) == 1) | |
1da177e4 LT |
575 | ps->next_free++; |
576 | ||
577 | atomic_inc(&ps->pending_count); | |
578 | return 0; | |
579 | } | |
580 | ||
581 | static void persistent_commit(struct exception_store *store, | |
028867ac | 582 | struct dm_snap_exception *e, |
1da177e4 LT |
583 | void (*callback) (void *, int success), |
584 | void *callback_context) | |
585 | { | |
1da177e4 LT |
586 | unsigned int i; |
587 | struct pstore *ps = get_info(store); | |
588 | struct disk_exception de; | |
589 | struct commit_callback *cb; | |
590 | ||
591 | de.old_chunk = e->old_chunk; | |
592 | de.new_chunk = e->new_chunk; | |
593 | write_exception(ps, ps->current_committed++, &de); | |
594 | ||
595 | /* | |
596 | * Add the callback to the back of the array. This code | |
597 | * is the only place where the callback array is | |
598 | * manipulated, and we know that it will never be called | |
599 | * multiple times concurrently. | |
600 | */ | |
601 | cb = ps->callbacks + ps->callback_count++; | |
602 | cb->callback = callback; | |
603 | cb->context = callback_context; | |
604 | ||
605 | /* | |
7c9e6c17 AK |
606 | * If there are exceptions in flight and we have not yet |
607 | * filled this metadata area there's nothing more to do. | |
1da177e4 | 608 | */ |
7c9e6c17 AK |
609 | if (!atomic_dec_and_test(&ps->pending_count) && |
610 | (ps->current_committed != ps->exceptions_per_area)) | |
611 | return; | |
1da177e4 | 612 | |
7acedc5b MP |
613 | /* |
614 | * If we completely filled the current area, then wipe the next one. | |
615 | */ | |
616 | if ((ps->current_committed == ps->exceptions_per_area) && | |
617 | zero_disk_area(ps, ps->current_area + 1)) | |
618 | ps->valid = 0; | |
619 | ||
7c9e6c17 AK |
620 | /* |
621 | * Commit exceptions to disk. | |
622 | */ | |
7acedc5b | 623 | if (ps->valid && area_io(ps, WRITE)) |
7c9e6c17 | 624 | ps->valid = 0; |
927ffe7c | 625 | |
7c9e6c17 AK |
626 | /* |
627 | * Advance to the next area if this one is full. | |
628 | */ | |
629 | if (ps->current_committed == ps->exceptions_per_area) { | |
7c9e6c17 AK |
630 | ps->current_committed = 0; |
631 | ps->current_area++; | |
632 | zero_memory_area(ps); | |
633 | } | |
1da177e4 | 634 | |
7c9e6c17 AK |
635 | for (i = 0; i < ps->callback_count; i++) { |
636 | cb = ps->callbacks + i; | |
637 | cb->callback(cb->context, ps->valid); | |
1da177e4 | 638 | } |
7c9e6c17 AK |
639 | |
640 | ps->callback_count = 0; | |
1da177e4 LT |
641 | } |
642 | ||
643 | static void persistent_drop(struct exception_store *store) | |
644 | { | |
645 | struct pstore *ps = get_info(store); | |
646 | ||
647 | ps->valid = 0; | |
648 | if (write_header(ps)) | |
649 | DMWARN("write header failed"); | |
650 | } | |
651 | ||
4c7e3bf4 | 652 | int dm_create_persistent(struct exception_store *store) |
1da177e4 | 653 | { |
1da177e4 LT |
654 | struct pstore *ps; |
655 | ||
1da177e4 LT |
656 | /* allocate the pstore */ |
657 | ps = kmalloc(sizeof(*ps), GFP_KERNEL); | |
4c7e3bf4 MM |
658 | if (!ps) |
659 | return -ENOMEM; | |
1da177e4 LT |
660 | |
661 | ps->snap = store->snap; | |
662 | ps->valid = 1; | |
663 | ps->version = SNAPSHOT_DISK_VERSION; | |
4c7e3bf4 | 664 | ps->area = NULL; |
1da177e4 LT |
665 | ps->next_free = 2; /* skipping the header and first area */ |
666 | ps->current_committed = 0; | |
667 | ||
1da177e4 LT |
668 | ps->callback_count = 0; |
669 | atomic_set(&ps->pending_count, 0); | |
c51c2752 | 670 | ps->callbacks = NULL; |
1da177e4 | 671 | |
fcac03ab MB |
672 | ps->metadata_wq = create_singlethread_workqueue("ksnaphd"); |
673 | if (!ps->metadata_wq) { | |
851a8a7f | 674 | kfree(ps); |
fcac03ab MB |
675 | DMERR("couldn't start header metadata update thread"); |
676 | return -ENOMEM; | |
677 | } | |
678 | ||
1da177e4 LT |
679 | store->destroy = persistent_destroy; |
680 | store->read_metadata = persistent_read_metadata; | |
681 | store->prepare_exception = persistent_prepare; | |
682 | store->commit_exception = persistent_commit; | |
683 | store->drop_snapshot = persistent_drop; | |
684 | store->fraction_full = persistent_fraction_full; | |
685 | store->context = ps; | |
686 | ||
687 | return 0; | |
1da177e4 LT |
688 | } |
689 | ||
690 | /*----------------------------------------------------------------- | |
691 | * Implementation of the store for non-persistent snapshots. | |
692 | *---------------------------------------------------------------*/ | |
693 | struct transient_c { | |
694 | sector_t next_free; | |
695 | }; | |
696 | ||
697 | static void transient_destroy(struct exception_store *store) | |
698 | { | |
699 | kfree(store->context); | |
700 | } | |
701 | ||
702 | static int transient_read_metadata(struct exception_store *store) | |
703 | { | |
704 | return 0; | |
705 | } | |
706 | ||
028867ac AK |
707 | static int transient_prepare(struct exception_store *store, |
708 | struct dm_snap_exception *e) | |
1da177e4 LT |
709 | { |
710 | struct transient_c *tc = (struct transient_c *) store->context; | |
711 | sector_t size = get_dev_size(store->snap->cow->bdev); | |
712 | ||
713 | if (size < (tc->next_free + store->snap->chunk_size)) | |
714 | return -1; | |
715 | ||
716 | e->new_chunk = sector_to_chunk(store->snap, tc->next_free); | |
717 | tc->next_free += store->snap->chunk_size; | |
718 | ||
719 | return 0; | |
720 | } | |
721 | ||
722 | static void transient_commit(struct exception_store *store, | |
028867ac AK |
723 | struct dm_snap_exception *e, |
724 | void (*callback) (void *, int success), | |
725 | void *callback_context) | |
1da177e4 LT |
726 | { |
727 | /* Just succeed */ | |
728 | callback(callback_context, 1); | |
729 | } | |
730 | ||
731 | static void transient_fraction_full(struct exception_store *store, | |
732 | sector_t *numerator, sector_t *denominator) | |
733 | { | |
734 | *numerator = ((struct transient_c *) store->context)->next_free; | |
735 | *denominator = get_dev_size(store->snap->cow->bdev); | |
736 | } | |
737 | ||
4c7e3bf4 | 738 | int dm_create_transient(struct exception_store *store) |
1da177e4 LT |
739 | { |
740 | struct transient_c *tc; | |
741 | ||
1da177e4 LT |
742 | store->destroy = transient_destroy; |
743 | store->read_metadata = transient_read_metadata; | |
744 | store->prepare_exception = transient_prepare; | |
745 | store->commit_exception = transient_commit; | |
4c7e3bf4 | 746 | store->drop_snapshot = NULL; |
1da177e4 | 747 | store->fraction_full = transient_fraction_full; |
1da177e4 LT |
748 | |
749 | tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL); | |
750 | if (!tc) | |
751 | return -ENOMEM; | |
752 | ||
753 | tc->next_free = 0; | |
754 | store->context = tc; | |
755 | ||
756 | return 0; | |
757 | } |