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 | 9 | |
b0d3cc01 | 10 | #include <linux/ctype.h> |
4db6bfe0 AK |
11 | #include <linux/mm.h> |
12 | #include <linux/pagemap.h> | |
13 | #include <linux/vmalloc.h> | |
daaa5f7c | 14 | #include <linux/export.h> |
4db6bfe0 AK |
15 | #include <linux/slab.h> |
16 | #include <linux/dm-io.h> | |
55494bf2 | 17 | #include "dm-bufio.h" |
4db6bfe0 AK |
18 | |
19 | #define DM_MSG_PREFIX "persistent snapshot" | |
20 | #define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */ | |
21 | ||
55b082e6 MP |
22 | #define DM_PREFETCH_CHUNKS 12 |
23 | ||
4db6bfe0 AK |
24 | /*----------------------------------------------------------------- |
25 | * Persistent snapshots, by persistent we mean that the snapshot | |
26 | * will survive a reboot. | |
27 | *---------------------------------------------------------------*/ | |
28 | ||
29 | /* | |
30 | * We need to store a record of which parts of the origin have | |
31 | * been copied to the snapshot device. The snapshot code | |
32 | * requires that we copy exception chunks to chunk aligned areas | |
33 | * of the COW store. It makes sense therefore, to store the | |
34 | * metadata in chunk size blocks. | |
35 | * | |
36 | * There is no backward or forward compatibility implemented, | |
37 | * snapshots with different disk versions than the kernel will | |
38 | * not be usable. It is expected that "lvcreate" will blank out | |
39 | * the start of a fresh COW device before calling the snapshot | |
40 | * constructor. | |
41 | * | |
42 | * The first chunk of the COW device just contains the header. | |
43 | * After this there is a chunk filled with exception metadata, | |
44 | * followed by as many exception chunks as can fit in the | |
45 | * metadata areas. | |
46 | * | |
47 | * All on disk structures are in little-endian format. The end | |
48 | * of the exceptions info is indicated by an exception with a | |
49 | * new_chunk of 0, which is invalid since it would point to the | |
50 | * header chunk. | |
51 | */ | |
52 | ||
53 | /* | |
54 | * Magic for persistent snapshots: "SnAp" - Feeble isn't it. | |
55 | */ | |
56 | #define SNAP_MAGIC 0x70416e53 | |
57 | ||
58 | /* | |
59 | * The on-disk version of the metadata. | |
60 | */ | |
61 | #define SNAPSHOT_DISK_VERSION 1 | |
62 | ||
4454a621 MP |
63 | #define NUM_SNAPSHOT_HDR_CHUNKS 1 |
64 | ||
4db6bfe0 | 65 | struct disk_header { |
283a8328 | 66 | __le32 magic; |
4db6bfe0 AK |
67 | |
68 | /* | |
69 | * Is this snapshot valid. There is no way of recovering | |
70 | * an invalid snapshot. | |
71 | */ | |
283a8328 | 72 | __le32 valid; |
4db6bfe0 AK |
73 | |
74 | /* | |
75 | * Simple, incrementing version. no backward | |
76 | * compatibility. | |
77 | */ | |
283a8328 | 78 | __le32 version; |
4db6bfe0 AK |
79 | |
80 | /* In sectors */ | |
283a8328 AK |
81 | __le32 chunk_size; |
82 | } __packed; | |
4db6bfe0 AK |
83 | |
84 | struct disk_exception { | |
283a8328 AK |
85 | __le64 old_chunk; |
86 | __le64 new_chunk; | |
87 | } __packed; | |
88 | ||
89 | struct core_exception { | |
4db6bfe0 AK |
90 | uint64_t old_chunk; |
91 | uint64_t new_chunk; | |
92 | }; | |
93 | ||
94 | struct commit_callback { | |
95 | void (*callback)(void *, int success); | |
96 | void *context; | |
97 | }; | |
98 | ||
99 | /* | |
100 | * The top level structure for a persistent exception store. | |
101 | */ | |
102 | struct pstore { | |
71fab00a | 103 | struct dm_exception_store *store; |
4db6bfe0 AK |
104 | int version; |
105 | int valid; | |
106 | uint32_t exceptions_per_area; | |
107 | ||
108 | /* | |
109 | * Now that we have an asynchronous kcopyd there is no | |
110 | * need for large chunk sizes, so it wont hurt to have a | |
111 | * whole chunks worth of metadata in memory at once. | |
112 | */ | |
113 | void *area; | |
114 | ||
115 | /* | |
116 | * An area of zeros used to clear the next area. | |
117 | */ | |
118 | void *zero_area; | |
119 | ||
61578dcd MP |
120 | /* |
121 | * An area used for header. The header can be written | |
122 | * concurrently with metadata (when invalidating the snapshot), | |
123 | * so it needs a separate buffer. | |
124 | */ | |
125 | void *header_area; | |
126 | ||
4db6bfe0 AK |
127 | /* |
128 | * Used to keep track of which metadata area the data in | |
129 | * 'chunk' refers to. | |
130 | */ | |
131 | chunk_t current_area; | |
132 | ||
133 | /* | |
134 | * The next free chunk for an exception. | |
4454a621 MP |
135 | * |
136 | * When creating exceptions, all the chunks here and above are | |
137 | * free. It holds the next chunk to be allocated. On rare | |
138 | * occasions (e.g. after a system crash) holes can be left in | |
139 | * the exception store because chunks can be committed out of | |
140 | * order. | |
141 | * | |
142 | * When merging exceptions, it does not necessarily mean all the | |
143 | * chunks here and above are free. It holds the value it would | |
144 | * have held if all chunks had been committed in order of | |
145 | * allocation. Consequently the value may occasionally be | |
146 | * slightly too low, but since it's only used for 'status' and | |
147 | * it can never reach its minimum value too early this doesn't | |
148 | * matter. | |
4db6bfe0 | 149 | */ |
4454a621 | 150 | |
4db6bfe0 AK |
151 | chunk_t next_free; |
152 | ||
153 | /* | |
154 | * The index of next free exception in the current | |
155 | * metadata area. | |
156 | */ | |
157 | uint32_t current_committed; | |
158 | ||
159 | atomic_t pending_count; | |
160 | uint32_t callback_count; | |
161 | struct commit_callback *callbacks; | |
162 | struct dm_io_client *io_client; | |
163 | ||
164 | struct workqueue_struct *metadata_wq; | |
165 | }; | |
166 | ||
4db6bfe0 AK |
167 | static int alloc_area(struct pstore *ps) |
168 | { | |
169 | int r = -ENOMEM; | |
170 | size_t len; | |
171 | ||
71fab00a | 172 | len = ps->store->chunk_size << SECTOR_SHIFT; |
4db6bfe0 AK |
173 | |
174 | /* | |
175 | * Allocate the chunk_size block of memory that will hold | |
176 | * a single metadata area. | |
177 | */ | |
178 | ps->area = vmalloc(len); | |
179 | if (!ps->area) | |
61578dcd | 180 | goto err_area; |
4db6bfe0 | 181 | |
e29e65aa | 182 | ps->zero_area = vzalloc(len); |
61578dcd MP |
183 | if (!ps->zero_area) |
184 | goto err_zero_area; | |
4db6bfe0 | 185 | |
61578dcd MP |
186 | ps->header_area = vmalloc(len); |
187 | if (!ps->header_area) | |
188 | goto err_header_area; | |
189 | ||
4db6bfe0 | 190 | return 0; |
61578dcd MP |
191 | |
192 | err_header_area: | |
193 | vfree(ps->zero_area); | |
194 | ||
195 | err_zero_area: | |
196 | vfree(ps->area); | |
197 | ||
198 | err_area: | |
199 | return r; | |
4db6bfe0 AK |
200 | } |
201 | ||
202 | static void free_area(struct pstore *ps) | |
203 | { | |
0c8f8632 | 204 | vfree(ps->area); |
4db6bfe0 | 205 | ps->area = NULL; |
0c8f8632 | 206 | vfree(ps->zero_area); |
4db6bfe0 | 207 | ps->zero_area = NULL; |
0c8f8632 | 208 | vfree(ps->header_area); |
61578dcd | 209 | ps->header_area = NULL; |
4db6bfe0 AK |
210 | } |
211 | ||
212 | struct mdata_req { | |
213 | struct dm_io_region *where; | |
214 | struct dm_io_request *io_req; | |
215 | struct work_struct work; | |
216 | int result; | |
217 | }; | |
218 | ||
219 | static void do_metadata(struct work_struct *work) | |
220 | { | |
221 | struct mdata_req *req = container_of(work, struct mdata_req, work); | |
222 | ||
223 | req->result = dm_io(req->io_req, 1, req->where, NULL); | |
224 | } | |
225 | ||
226 | /* | |
227 | * Read or write a chunk aligned and sized block of data from a device. | |
228 | */ | |
02d2fd31 MP |
229 | static int chunk_io(struct pstore *ps, void *area, chunk_t chunk, int rw, |
230 | int metadata) | |
4db6bfe0 AK |
231 | { |
232 | struct dm_io_region where = { | |
fc56f6fb | 233 | .bdev = dm_snap_cow(ps->store->snap)->bdev, |
71fab00a JB |
234 | .sector = ps->store->chunk_size * chunk, |
235 | .count = ps->store->chunk_size, | |
4db6bfe0 AK |
236 | }; |
237 | struct dm_io_request io_req = { | |
238 | .bi_rw = rw, | |
239 | .mem.type = DM_IO_VMA, | |
02d2fd31 | 240 | .mem.ptr.vma = area, |
4db6bfe0 AK |
241 | .client = ps->io_client, |
242 | .notify.fn = NULL, | |
243 | }; | |
244 | struct mdata_req req; | |
245 | ||
246 | if (!metadata) | |
247 | return dm_io(&io_req, 1, &where, NULL); | |
248 | ||
249 | req.where = &where; | |
250 | req.io_req = &io_req; | |
251 | ||
252 | /* | |
253 | * Issue the synchronous I/O from a different thread | |
254 | * to avoid generic_make_request recursion. | |
255 | */ | |
ca1cab37 | 256 | INIT_WORK_ONSTACK(&req.work, do_metadata); |
4db6bfe0 | 257 | queue_work(ps->metadata_wq, &req.work); |
5ea330a7 | 258 | flush_workqueue(ps->metadata_wq); |
c1a64160 | 259 | destroy_work_on_stack(&req.work); |
4db6bfe0 AK |
260 | |
261 | return req.result; | |
262 | } | |
263 | ||
264 | /* | |
265 | * Convert a metadata area index to a chunk index. | |
266 | */ | |
267 | static chunk_t area_location(struct pstore *ps, chunk_t area) | |
268 | { | |
87c961cb | 269 | return NUM_SNAPSHOT_HDR_CHUNKS + ((ps->exceptions_per_area + 1) * area); |
4db6bfe0 AK |
270 | } |
271 | ||
e9c6a182 MP |
272 | static void skip_metadata(struct pstore *ps) |
273 | { | |
274 | uint32_t stride = ps->exceptions_per_area + 1; | |
275 | chunk_t next_free = ps->next_free; | |
276 | if (sector_div(next_free, stride) == NUM_SNAPSHOT_HDR_CHUNKS) | |
277 | ps->next_free++; | |
278 | } | |
279 | ||
4db6bfe0 AK |
280 | /* |
281 | * Read or write a metadata area. Remembering to skip the first | |
282 | * chunk which holds the header. | |
283 | */ | |
284 | static int area_io(struct pstore *ps, int rw) | |
285 | { | |
286 | int r; | |
287 | chunk_t chunk; | |
288 | ||
289 | chunk = area_location(ps, ps->current_area); | |
290 | ||
02d2fd31 | 291 | r = chunk_io(ps, ps->area, chunk, rw, 0); |
4db6bfe0 AK |
292 | if (r) |
293 | return r; | |
294 | ||
295 | return 0; | |
296 | } | |
297 | ||
298 | static void zero_memory_area(struct pstore *ps) | |
299 | { | |
71fab00a | 300 | memset(ps->area, 0, ps->store->chunk_size << SECTOR_SHIFT); |
4db6bfe0 AK |
301 | } |
302 | ||
303 | static int zero_disk_area(struct pstore *ps, chunk_t area) | |
304 | { | |
02d2fd31 | 305 | return chunk_io(ps, ps->zero_area, area_location(ps, area), WRITE, 0); |
4db6bfe0 AK |
306 | } |
307 | ||
308 | static int read_header(struct pstore *ps, int *new_snapshot) | |
309 | { | |
310 | int r; | |
311 | struct disk_header *dh; | |
df96eee6 | 312 | unsigned chunk_size; |
4db6bfe0 | 313 | int chunk_size_supplied = 1; |
ae0b7448 | 314 | char *chunk_err; |
4db6bfe0 AK |
315 | |
316 | /* | |
df96eee6 MP |
317 | * Use default chunk size (or logical_block_size, if larger) |
318 | * if none supplied | |
4db6bfe0 | 319 | */ |
71fab00a JB |
320 | if (!ps->store->chunk_size) { |
321 | ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS, | |
fc56f6fb MS |
322 | bdev_logical_block_size(dm_snap_cow(ps->store->snap)-> |
323 | bdev) >> 9); | |
71fab00a | 324 | ps->store->chunk_mask = ps->store->chunk_size - 1; |
a3d939ae | 325 | ps->store->chunk_shift = __ffs(ps->store->chunk_size); |
4db6bfe0 AK |
326 | chunk_size_supplied = 0; |
327 | } | |
328 | ||
bda8efec | 329 | ps->io_client = dm_io_client_create(); |
4db6bfe0 AK |
330 | if (IS_ERR(ps->io_client)) |
331 | return PTR_ERR(ps->io_client); | |
332 | ||
333 | r = alloc_area(ps); | |
334 | if (r) | |
335 | return r; | |
336 | ||
61578dcd | 337 | r = chunk_io(ps, ps->header_area, 0, READ, 1); |
4db6bfe0 AK |
338 | if (r) |
339 | goto bad; | |
340 | ||
61578dcd | 341 | dh = ps->header_area; |
4db6bfe0 AK |
342 | |
343 | if (le32_to_cpu(dh->magic) == 0) { | |
344 | *new_snapshot = 1; | |
345 | return 0; | |
346 | } | |
347 | ||
348 | if (le32_to_cpu(dh->magic) != SNAP_MAGIC) { | |
349 | DMWARN("Invalid or corrupt snapshot"); | |
350 | r = -ENXIO; | |
351 | goto bad; | |
352 | } | |
353 | ||
354 | *new_snapshot = 0; | |
355 | ps->valid = le32_to_cpu(dh->valid); | |
356 | ps->version = le32_to_cpu(dh->version); | |
357 | chunk_size = le32_to_cpu(dh->chunk_size); | |
358 | ||
ae0b7448 | 359 | if (ps->store->chunk_size == chunk_size) |
4db6bfe0 AK |
360 | return 0; |
361 | ||
ae0b7448 | 362 | if (chunk_size_supplied) |
df96eee6 MP |
363 | DMWARN("chunk size %u in device metadata overrides " |
364 | "table chunk size of %u.", | |
365 | chunk_size, ps->store->chunk_size); | |
4db6bfe0 AK |
366 | |
367 | /* We had a bogus chunk_size. Fix stuff up. */ | |
368 | free_area(ps); | |
369 | ||
ae0b7448 MP |
370 | r = dm_exception_store_set_chunk_size(ps->store, chunk_size, |
371 | &chunk_err); | |
372 | if (r) { | |
df96eee6 MP |
373 | DMERR("invalid on-disk chunk size %u: %s.", |
374 | chunk_size, chunk_err); | |
ae0b7448 MP |
375 | return r; |
376 | } | |
4db6bfe0 | 377 | |
4db6bfe0 AK |
378 | r = alloc_area(ps); |
379 | return r; | |
380 | ||
381 | bad: | |
382 | free_area(ps); | |
383 | return r; | |
384 | } | |
385 | ||
386 | static int write_header(struct pstore *ps) | |
387 | { | |
388 | struct disk_header *dh; | |
389 | ||
61578dcd | 390 | memset(ps->header_area, 0, ps->store->chunk_size << SECTOR_SHIFT); |
4db6bfe0 | 391 | |
61578dcd | 392 | dh = ps->header_area; |
4db6bfe0 AK |
393 | dh->magic = cpu_to_le32(SNAP_MAGIC); |
394 | dh->valid = cpu_to_le32(ps->valid); | |
395 | dh->version = cpu_to_le32(ps->version); | |
71fab00a | 396 | dh->chunk_size = cpu_to_le32(ps->store->chunk_size); |
4db6bfe0 | 397 | |
61578dcd | 398 | return chunk_io(ps, ps->header_area, 0, WRITE, 1); |
4db6bfe0 AK |
399 | } |
400 | ||
401 | /* | |
402 | * Access functions for the disk exceptions, these do the endian conversions. | |
403 | */ | |
2cadabd5 MP |
404 | static struct disk_exception *get_exception(struct pstore *ps, void *ps_area, |
405 | uint32_t index) | |
4db6bfe0 AK |
406 | { |
407 | BUG_ON(index >= ps->exceptions_per_area); | |
408 | ||
2cadabd5 | 409 | return ((struct disk_exception *) ps_area) + index; |
4db6bfe0 AK |
410 | } |
411 | ||
2cadabd5 | 412 | static void read_exception(struct pstore *ps, void *ps_area, |
283a8328 | 413 | uint32_t index, struct core_exception *result) |
4db6bfe0 | 414 | { |
2cadabd5 | 415 | struct disk_exception *de = get_exception(ps, ps_area, index); |
4db6bfe0 AK |
416 | |
417 | /* copy it */ | |
283a8328 AK |
418 | result->old_chunk = le64_to_cpu(de->old_chunk); |
419 | result->new_chunk = le64_to_cpu(de->new_chunk); | |
4db6bfe0 AK |
420 | } |
421 | ||
422 | static void write_exception(struct pstore *ps, | |
283a8328 | 423 | uint32_t index, struct core_exception *e) |
4db6bfe0 | 424 | { |
2cadabd5 | 425 | struct disk_exception *de = get_exception(ps, ps->area, index); |
4db6bfe0 AK |
426 | |
427 | /* copy it */ | |
283a8328 AK |
428 | de->old_chunk = cpu_to_le64(e->old_chunk); |
429 | de->new_chunk = cpu_to_le64(e->new_chunk); | |
4db6bfe0 AK |
430 | } |
431 | ||
4454a621 MP |
432 | static void clear_exception(struct pstore *ps, uint32_t index) |
433 | { | |
2cadabd5 | 434 | struct disk_exception *de = get_exception(ps, ps->area, index); |
4454a621 MP |
435 | |
436 | /* clear it */ | |
283a8328 AK |
437 | de->old_chunk = 0; |
438 | de->new_chunk = 0; | |
4454a621 MP |
439 | } |
440 | ||
4db6bfe0 AK |
441 | /* |
442 | * Registers the exceptions that are present in the current area. | |
443 | * 'full' is filled in to indicate if the area has been | |
444 | * filled. | |
445 | */ | |
2cadabd5 | 446 | static int insert_exceptions(struct pstore *ps, void *ps_area, |
a159c1ac JB |
447 | int (*callback)(void *callback_context, |
448 | chunk_t old, chunk_t new), | |
449 | void *callback_context, | |
450 | int *full) | |
4db6bfe0 AK |
451 | { |
452 | int r; | |
453 | unsigned int i; | |
283a8328 | 454 | struct core_exception e; |
4db6bfe0 AK |
455 | |
456 | /* presume the area is full */ | |
457 | *full = 1; | |
458 | ||
459 | for (i = 0; i < ps->exceptions_per_area; i++) { | |
2cadabd5 | 460 | read_exception(ps, ps_area, i, &e); |
4db6bfe0 AK |
461 | |
462 | /* | |
463 | * If the new_chunk is pointing at the start of | |
464 | * the COW device, where the first metadata area | |
465 | * is we know that we've hit the end of the | |
466 | * exceptions. Therefore the area is not full. | |
467 | */ | |
283a8328 | 468 | if (e.new_chunk == 0LL) { |
4db6bfe0 AK |
469 | ps->current_committed = i; |
470 | *full = 0; | |
471 | break; | |
472 | } | |
473 | ||
474 | /* | |
475 | * Keep track of the start of the free chunks. | |
476 | */ | |
283a8328 AK |
477 | if (ps->next_free <= e.new_chunk) |
478 | ps->next_free = e.new_chunk + 1; | |
4db6bfe0 AK |
479 | |
480 | /* | |
481 | * Otherwise we add the exception to the snapshot. | |
482 | */ | |
283a8328 | 483 | r = callback(callback_context, e.old_chunk, e.new_chunk); |
4db6bfe0 AK |
484 | if (r) |
485 | return r; | |
486 | } | |
487 | ||
488 | return 0; | |
489 | } | |
490 | ||
a159c1ac JB |
491 | static int read_exceptions(struct pstore *ps, |
492 | int (*callback)(void *callback_context, chunk_t old, | |
493 | chunk_t new), | |
494 | void *callback_context) | |
4db6bfe0 AK |
495 | { |
496 | int r, full = 1; | |
55494bf2 | 497 | struct dm_bufio_client *client; |
55b082e6 | 498 | chunk_t prefetch_area = 0; |
55494bf2 MP |
499 | |
500 | client = dm_bufio_client_create(dm_snap_cow(ps->store->snap)->bdev, | |
501 | ps->store->chunk_size << SECTOR_SHIFT, | |
502 | 1, 0, NULL, NULL); | |
503 | ||
504 | if (IS_ERR(client)) | |
505 | return PTR_ERR(client); | |
4db6bfe0 | 506 | |
55b082e6 MP |
507 | /* |
508 | * Setup for one current buffer + desired readahead buffers. | |
509 | */ | |
510 | dm_bufio_set_minimum_buffers(client, 1 + DM_PREFETCH_CHUNKS); | |
511 | ||
4db6bfe0 AK |
512 | /* |
513 | * Keeping reading chunks and inserting exceptions until | |
514 | * we find a partially full area. | |
515 | */ | |
516 | for (ps->current_area = 0; full; ps->current_area++) { | |
55494bf2 MP |
517 | struct dm_buffer *bp; |
518 | void *area; | |
55b082e6 MP |
519 | chunk_t chunk; |
520 | ||
521 | if (unlikely(prefetch_area < ps->current_area)) | |
522 | prefetch_area = ps->current_area; | |
523 | ||
524 | if (DM_PREFETCH_CHUNKS) do { | |
525 | chunk_t pf_chunk = area_location(ps, prefetch_area); | |
526 | if (unlikely(pf_chunk >= dm_bufio_get_device_size(client))) | |
527 | break; | |
528 | dm_bufio_prefetch(client, pf_chunk, 1); | |
529 | prefetch_area++; | |
530 | if (unlikely(!prefetch_area)) | |
531 | break; | |
532 | } while (prefetch_area <= ps->current_area + DM_PREFETCH_CHUNKS); | |
533 | ||
534 | chunk = area_location(ps, ps->current_area); | |
55494bf2 MP |
535 | |
536 | area = dm_bufio_read(client, chunk, &bp); | |
fc0a4461 | 537 | if (IS_ERR(area)) { |
55494bf2 MP |
538 | r = PTR_ERR(area); |
539 | goto ret_destroy_bufio; | |
540 | } | |
4db6bfe0 | 541 | |
55494bf2 | 542 | r = insert_exceptions(ps, area, callback, callback_context, |
2cadabd5 | 543 | &full); |
55494bf2 | 544 | |
2c945820 MP |
545 | if (!full) |
546 | memcpy(ps->area, area, ps->store->chunk_size << SECTOR_SHIFT); | |
547 | ||
55494bf2 MP |
548 | dm_bufio_release(bp); |
549 | ||
550 | dm_bufio_forget(client, chunk); | |
551 | ||
552 | if (unlikely(r)) | |
553 | goto ret_destroy_bufio; | |
4db6bfe0 AK |
554 | } |
555 | ||
556 | ps->current_area--; | |
557 | ||
e9c6a182 MP |
558 | skip_metadata(ps); |
559 | ||
55494bf2 MP |
560 | r = 0; |
561 | ||
562 | ret_destroy_bufio: | |
563 | dm_bufio_client_destroy(client); | |
564 | ||
565 | return r; | |
4db6bfe0 AK |
566 | } |
567 | ||
568 | static struct pstore *get_info(struct dm_exception_store *store) | |
569 | { | |
570 | return (struct pstore *) store->context; | |
571 | } | |
572 | ||
985903bb MS |
573 | static void persistent_usage(struct dm_exception_store *store, |
574 | sector_t *total_sectors, | |
575 | sector_t *sectors_allocated, | |
576 | sector_t *metadata_sectors) | |
4db6bfe0 | 577 | { |
985903bb MS |
578 | struct pstore *ps = get_info(store); |
579 | ||
580 | *sectors_allocated = ps->next_free * store->chunk_size; | |
fc56f6fb | 581 | *total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev); |
985903bb MS |
582 | |
583 | /* | |
584 | * First chunk is the fixed header. | |
585 | * Then there are (ps->current_area + 1) metadata chunks, each one | |
586 | * separated from the next by ps->exceptions_per_area data chunks. | |
587 | */ | |
4454a621 MP |
588 | *metadata_sectors = (ps->current_area + 1 + NUM_SNAPSHOT_HDR_CHUNKS) * |
589 | store->chunk_size; | |
4db6bfe0 AK |
590 | } |
591 | ||
493df71c | 592 | static void persistent_dtr(struct dm_exception_store *store) |
4db6bfe0 AK |
593 | { |
594 | struct pstore *ps = get_info(store); | |
595 | ||
596 | destroy_workqueue(ps->metadata_wq); | |
a32079ce JB |
597 | |
598 | /* Created in read_header */ | |
599 | if (ps->io_client) | |
600 | dm_io_client_destroy(ps->io_client); | |
4db6bfe0 | 601 | free_area(ps); |
a32079ce JB |
602 | |
603 | /* Allocated in persistent_read_metadata */ | |
0c8f8632 | 604 | vfree(ps->callbacks); |
a32079ce | 605 | |
4db6bfe0 AK |
606 | kfree(ps); |
607 | } | |
608 | ||
a159c1ac JB |
609 | static int persistent_read_metadata(struct dm_exception_store *store, |
610 | int (*callback)(void *callback_context, | |
611 | chunk_t old, chunk_t new), | |
612 | void *callback_context) | |
4db6bfe0 AK |
613 | { |
614 | int r, uninitialized_var(new_snapshot); | |
615 | struct pstore *ps = get_info(store); | |
616 | ||
617 | /* | |
618 | * Read the snapshot header. | |
619 | */ | |
620 | r = read_header(ps, &new_snapshot); | |
621 | if (r) | |
622 | return r; | |
623 | ||
624 | /* | |
625 | * Now we know correct chunk_size, complete the initialisation. | |
626 | */ | |
71fab00a JB |
627 | ps->exceptions_per_area = (ps->store->chunk_size << SECTOR_SHIFT) / |
628 | sizeof(struct disk_exception); | |
4db6bfe0 | 629 | ps->callbacks = dm_vcalloc(ps->exceptions_per_area, |
a2d2b034 | 630 | sizeof(*ps->callbacks)); |
4db6bfe0 AK |
631 | if (!ps->callbacks) |
632 | return -ENOMEM; | |
633 | ||
634 | /* | |
635 | * Do we need to setup a new snapshot ? | |
636 | */ | |
637 | if (new_snapshot) { | |
638 | r = write_header(ps); | |
639 | if (r) { | |
640 | DMWARN("write_header failed"); | |
641 | return r; | |
642 | } | |
643 | ||
644 | ps->current_area = 0; | |
645 | zero_memory_area(ps); | |
646 | r = zero_disk_area(ps, 0); | |
f5acc834 | 647 | if (r) |
4db6bfe0 | 648 | DMWARN("zero_disk_area(0) failed"); |
f5acc834 JB |
649 | return r; |
650 | } | |
651 | /* | |
652 | * Sanity checks. | |
653 | */ | |
654 | if (ps->version != SNAPSHOT_DISK_VERSION) { | |
655 | DMWARN("unable to handle snapshot disk version %d", | |
656 | ps->version); | |
657 | return -EINVAL; | |
658 | } | |
4db6bfe0 | 659 | |
f5acc834 JB |
660 | /* |
661 | * Metadata are valid, but snapshot is invalidated | |
662 | */ | |
663 | if (!ps->valid) | |
664 | return 1; | |
4db6bfe0 | 665 | |
f5acc834 JB |
666 | /* |
667 | * Read the metadata. | |
668 | */ | |
669 | r = read_exceptions(ps, callback, callback_context); | |
4db6bfe0 | 670 | |
f5acc834 | 671 | return r; |
4db6bfe0 AK |
672 | } |
673 | ||
a159c1ac | 674 | static int persistent_prepare_exception(struct dm_exception_store *store, |
1d4989c8 | 675 | struct dm_exception *e) |
4db6bfe0 AK |
676 | { |
677 | struct pstore *ps = get_info(store); | |
fc56f6fb | 678 | sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev); |
4db6bfe0 AK |
679 | |
680 | /* Is there enough room ? */ | |
d0216849 | 681 | if (size < ((ps->next_free + 1) * store->chunk_size)) |
4db6bfe0 AK |
682 | return -ENOSPC; |
683 | ||
684 | e->new_chunk = ps->next_free; | |
685 | ||
686 | /* | |
687 | * Move onto the next free pending, making sure to take | |
688 | * into account the location of the metadata chunks. | |
689 | */ | |
e9c6a182 MP |
690 | ps->next_free++; |
691 | skip_metadata(ps); | |
4db6bfe0 AK |
692 | |
693 | atomic_inc(&ps->pending_count); | |
694 | return 0; | |
695 | } | |
696 | ||
a159c1ac | 697 | static void persistent_commit_exception(struct dm_exception_store *store, |
1d4989c8 | 698 | struct dm_exception *e, |
a159c1ac JB |
699 | void (*callback) (void *, int success), |
700 | void *callback_context) | |
4db6bfe0 AK |
701 | { |
702 | unsigned int i; | |
703 | struct pstore *ps = get_info(store); | |
283a8328 | 704 | struct core_exception ce; |
4db6bfe0 AK |
705 | struct commit_callback *cb; |
706 | ||
283a8328 AK |
707 | ce.old_chunk = e->old_chunk; |
708 | ce.new_chunk = e->new_chunk; | |
709 | write_exception(ps, ps->current_committed++, &ce); | |
4db6bfe0 AK |
710 | |
711 | /* | |
712 | * Add the callback to the back of the array. This code | |
713 | * is the only place where the callback array is | |
714 | * manipulated, and we know that it will never be called | |
715 | * multiple times concurrently. | |
716 | */ | |
717 | cb = ps->callbacks + ps->callback_count++; | |
718 | cb->callback = callback; | |
719 | cb->context = callback_context; | |
720 | ||
721 | /* | |
722 | * If there are exceptions in flight and we have not yet | |
723 | * filled this metadata area there's nothing more to do. | |
724 | */ | |
725 | if (!atomic_dec_and_test(&ps->pending_count) && | |
726 | (ps->current_committed != ps->exceptions_per_area)) | |
727 | return; | |
728 | ||
729 | /* | |
730 | * If we completely filled the current area, then wipe the next one. | |
731 | */ | |
732 | if ((ps->current_committed == ps->exceptions_per_area) && | |
a2d2b034 | 733 | zero_disk_area(ps, ps->current_area + 1)) |
4db6bfe0 AK |
734 | ps->valid = 0; |
735 | ||
736 | /* | |
737 | * Commit exceptions to disk. | |
738 | */ | |
d87f4c14 | 739 | if (ps->valid && area_io(ps, WRITE_FLUSH_FUA)) |
4db6bfe0 AK |
740 | ps->valid = 0; |
741 | ||
742 | /* | |
743 | * Advance to the next area if this one is full. | |
744 | */ | |
745 | if (ps->current_committed == ps->exceptions_per_area) { | |
746 | ps->current_committed = 0; | |
747 | ps->current_area++; | |
748 | zero_memory_area(ps); | |
749 | } | |
750 | ||
751 | for (i = 0; i < ps->callback_count; i++) { | |
752 | cb = ps->callbacks + i; | |
753 | cb->callback(cb->context, ps->valid); | |
754 | } | |
755 | ||
756 | ps->callback_count = 0; | |
757 | } | |
758 | ||
4454a621 MP |
759 | static int persistent_prepare_merge(struct dm_exception_store *store, |
760 | chunk_t *last_old_chunk, | |
761 | chunk_t *last_new_chunk) | |
762 | { | |
763 | struct pstore *ps = get_info(store); | |
283a8328 | 764 | struct core_exception ce; |
4454a621 MP |
765 | int nr_consecutive; |
766 | int r; | |
767 | ||
768 | /* | |
769 | * When current area is empty, move back to preceding area. | |
770 | */ | |
771 | if (!ps->current_committed) { | |
772 | /* | |
773 | * Have we finished? | |
774 | */ | |
775 | if (!ps->current_area) | |
776 | return 0; | |
777 | ||
778 | ps->current_area--; | |
779 | r = area_io(ps, READ); | |
780 | if (r < 0) | |
781 | return r; | |
782 | ps->current_committed = ps->exceptions_per_area; | |
783 | } | |
784 | ||
2cadabd5 | 785 | read_exception(ps, ps->area, ps->current_committed - 1, &ce); |
283a8328 AK |
786 | *last_old_chunk = ce.old_chunk; |
787 | *last_new_chunk = ce.new_chunk; | |
4454a621 MP |
788 | |
789 | /* | |
790 | * Find number of consecutive chunks within the current area, | |
791 | * working backwards. | |
792 | */ | |
793 | for (nr_consecutive = 1; nr_consecutive < ps->current_committed; | |
794 | nr_consecutive++) { | |
2cadabd5 MP |
795 | read_exception(ps, ps->area, |
796 | ps->current_committed - 1 - nr_consecutive, &ce); | |
283a8328 AK |
797 | if (ce.old_chunk != *last_old_chunk - nr_consecutive || |
798 | ce.new_chunk != *last_new_chunk - nr_consecutive) | |
4454a621 MP |
799 | break; |
800 | } | |
801 | ||
802 | return nr_consecutive; | |
803 | } | |
804 | ||
805 | static int persistent_commit_merge(struct dm_exception_store *store, | |
806 | int nr_merged) | |
807 | { | |
808 | int r, i; | |
809 | struct pstore *ps = get_info(store); | |
810 | ||
811 | BUG_ON(nr_merged > ps->current_committed); | |
812 | ||
813 | for (i = 0; i < nr_merged; i++) | |
814 | clear_exception(ps, ps->current_committed - 1 - i); | |
815 | ||
762a80d9 | 816 | r = area_io(ps, WRITE_FLUSH_FUA); |
4454a621 MP |
817 | if (r < 0) |
818 | return r; | |
819 | ||
820 | ps->current_committed -= nr_merged; | |
821 | ||
822 | /* | |
823 | * At this stage, only persistent_usage() uses ps->next_free, so | |
824 | * we make no attempt to keep ps->next_free strictly accurate | |
825 | * as exceptions may have been committed out-of-order originally. | |
826 | * Once a snapshot has become merging, we set it to the value it | |
827 | * would have held had all the exceptions been committed in order. | |
828 | * | |
829 | * ps->current_area does not get reduced by prepare_merge() until | |
830 | * after commit_merge() has removed the nr_merged previous exceptions. | |
831 | */ | |
87c961cb TK |
832 | ps->next_free = area_location(ps, ps->current_area) + |
833 | ps->current_committed + 1; | |
4454a621 MP |
834 | |
835 | return 0; | |
836 | } | |
837 | ||
a159c1ac | 838 | static void persistent_drop_snapshot(struct dm_exception_store *store) |
4db6bfe0 AK |
839 | { |
840 | struct pstore *ps = get_info(store); | |
841 | ||
842 | ps->valid = 0; | |
843 | if (write_header(ps)) | |
844 | DMWARN("write header failed"); | |
845 | } | |
846 | ||
b0d3cc01 | 847 | static int persistent_ctr(struct dm_exception_store *store, char *options) |
4db6bfe0 AK |
848 | { |
849 | struct pstore *ps; | |
a2a678ed | 850 | int r; |
4db6bfe0 AK |
851 | |
852 | /* allocate the pstore */ | |
a32079ce | 853 | ps = kzalloc(sizeof(*ps), GFP_KERNEL); |
4db6bfe0 AK |
854 | if (!ps) |
855 | return -ENOMEM; | |
856 | ||
71fab00a | 857 | ps->store = store; |
4db6bfe0 AK |
858 | ps->valid = 1; |
859 | ps->version = SNAPSHOT_DISK_VERSION; | |
860 | ps->area = NULL; | |
61578dcd MP |
861 | ps->zero_area = NULL; |
862 | ps->header_area = NULL; | |
4454a621 | 863 | ps->next_free = NUM_SNAPSHOT_HDR_CHUNKS + 1; /* header and 1st area */ |
4db6bfe0 AK |
864 | ps->current_committed = 0; |
865 | ||
866 | ps->callback_count = 0; | |
867 | atomic_set(&ps->pending_count, 0); | |
868 | ps->callbacks = NULL; | |
869 | ||
239c8dd5 | 870 | ps->metadata_wq = alloc_workqueue("ksnaphd", WQ_MEM_RECLAIM, 0); |
4db6bfe0 | 871 | if (!ps->metadata_wq) { |
4db6bfe0 | 872 | DMERR("couldn't start header metadata update thread"); |
a2a678ed SM |
873 | r = -ENOMEM; |
874 | goto err_workqueue; | |
4db6bfe0 AK |
875 | } |
876 | ||
b0d3cc01 MS |
877 | if (options) { |
878 | char overflow = toupper(options[0]); | |
879 | if (overflow == 'O') | |
880 | store->userspace_supports_overflow = true; | |
881 | else { | |
882 | DMERR("Unsupported persistent store option: %s", options); | |
a2a678ed SM |
883 | r = -EINVAL; |
884 | goto err_options; | |
b0d3cc01 MS |
885 | } |
886 | } | |
887 | ||
4db6bfe0 AK |
888 | store->context = ps; |
889 | ||
890 | return 0; | |
a2a678ed SM |
891 | |
892 | err_options: | |
893 | destroy_workqueue(ps->metadata_wq); | |
894 | err_workqueue: | |
895 | kfree(ps); | |
896 | ||
897 | return r; | |
4db6bfe0 AK |
898 | } |
899 | ||
1e302a92 JB |
900 | static unsigned persistent_status(struct dm_exception_store *store, |
901 | status_type_t status, char *result, | |
902 | unsigned maxlen) | |
493df71c | 903 | { |
1e302a92 JB |
904 | unsigned sz = 0; |
905 | ||
906 | switch (status) { | |
907 | case STATUSTYPE_INFO: | |
908 | break; | |
909 | case STATUSTYPE_TABLE: | |
b0d3cc01 MS |
910 | DMEMIT(" %s %llu", store->userspace_supports_overflow ? "PO" : "P", |
911 | (unsigned long long)store->chunk_size); | |
1e302a92 | 912 | } |
493df71c JB |
913 | |
914 | return sz; | |
915 | } | |
916 | ||
917 | static struct dm_exception_store_type _persistent_type = { | |
918 | .name = "persistent", | |
919 | .module = THIS_MODULE, | |
920 | .ctr = persistent_ctr, | |
921 | .dtr = persistent_dtr, | |
922 | .read_metadata = persistent_read_metadata, | |
923 | .prepare_exception = persistent_prepare_exception, | |
924 | .commit_exception = persistent_commit_exception, | |
4454a621 MP |
925 | .prepare_merge = persistent_prepare_merge, |
926 | .commit_merge = persistent_commit_merge, | |
493df71c | 927 | .drop_snapshot = persistent_drop_snapshot, |
985903bb | 928 | .usage = persistent_usage, |
493df71c JB |
929 | .status = persistent_status, |
930 | }; | |
931 | ||
932 | static struct dm_exception_store_type _persistent_compat_type = { | |
933 | .name = "P", | |
934 | .module = THIS_MODULE, | |
935 | .ctr = persistent_ctr, | |
936 | .dtr = persistent_dtr, | |
937 | .read_metadata = persistent_read_metadata, | |
938 | .prepare_exception = persistent_prepare_exception, | |
939 | .commit_exception = persistent_commit_exception, | |
4454a621 MP |
940 | .prepare_merge = persistent_prepare_merge, |
941 | .commit_merge = persistent_commit_merge, | |
493df71c | 942 | .drop_snapshot = persistent_drop_snapshot, |
985903bb | 943 | .usage = persistent_usage, |
493df71c JB |
944 | .status = persistent_status, |
945 | }; | |
946 | ||
4db6bfe0 AK |
947 | int dm_persistent_snapshot_init(void) |
948 | { | |
493df71c JB |
949 | int r; |
950 | ||
951 | r = dm_exception_store_type_register(&_persistent_type); | |
952 | if (r) { | |
953 | DMERR("Unable to register persistent exception store type"); | |
954 | return r; | |
955 | } | |
956 | ||
957 | r = dm_exception_store_type_register(&_persistent_compat_type); | |
958 | if (r) { | |
959 | DMERR("Unable to register old-style persistent exception " | |
960 | "store type"); | |
961 | dm_exception_store_type_unregister(&_persistent_type); | |
962 | return r; | |
963 | } | |
964 | ||
965 | return r; | |
4db6bfe0 AK |
966 | } |
967 | ||
968 | void dm_persistent_snapshot_exit(void) | |
969 | { | |
493df71c JB |
970 | dm_exception_store_type_unregister(&_persistent_type); |
971 | dm_exception_store_type_unregister(&_persistent_compat_type); | |
4db6bfe0 | 972 | } |