Commit | Line | Data |
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3bd94003 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
4db6bfe0 AK |
2 | /* |
3 | * Copyright (C) 2001-2002 Sistina Software (UK) Limited. | |
4 | * Copyright (C) 2006-2008 Red Hat GmbH | |
5 | * | |
6 | * This file is released under the GPL. | |
7 | */ | |
8 | ||
9 | #include "dm-exception-store.h" | |
4db6bfe0 | 10 | |
b0d3cc01 | 11 | #include <linux/ctype.h> |
4db6bfe0 AK |
12 | #include <linux/mm.h> |
13 | #include <linux/pagemap.h> | |
14 | #include <linux/vmalloc.h> | |
daaa5f7c | 15 | #include <linux/export.h> |
4db6bfe0 AK |
16 | #include <linux/slab.h> |
17 | #include <linux/dm-io.h> | |
afa53df8 | 18 | #include <linux/dm-bufio.h> |
4db6bfe0 AK |
19 | |
20 | #define DM_MSG_PREFIX "persistent snapshot" | |
ad6bf88a | 21 | #define DM_CHUNK_SIZE_DEFAULT_SECTORS 32U /* 16KB */ |
4db6bfe0 | 22 | |
55b082e6 MP |
23 | #define DM_PREFETCH_CHUNKS 12 |
24 | ||
a4a82ce3 HM |
25 | /* |
26 | *--------------------------------------------------------------- | |
4db6bfe0 AK |
27 | * Persistent snapshots, by persistent we mean that the snapshot |
28 | * will survive a reboot. | |
a4a82ce3 HM |
29 | *--------------------------------------------------------------- |
30 | */ | |
4db6bfe0 AK |
31 | |
32 | /* | |
33 | * We need to store a record of which parts of the origin have | |
34 | * been copied to the snapshot device. The snapshot code | |
35 | * requires that we copy exception chunks to chunk aligned areas | |
36 | * of the COW store. It makes sense therefore, to store the | |
37 | * metadata in chunk size blocks. | |
38 | * | |
39 | * There is no backward or forward compatibility implemented, | |
40 | * snapshots with different disk versions than the kernel will | |
41 | * not be usable. It is expected that "lvcreate" will blank out | |
42 | * the start of a fresh COW device before calling the snapshot | |
43 | * constructor. | |
44 | * | |
45 | * The first chunk of the COW device just contains the header. | |
46 | * After this there is a chunk filled with exception metadata, | |
47 | * followed by as many exception chunks as can fit in the | |
48 | * metadata areas. | |
49 | * | |
50 | * All on disk structures are in little-endian format. The end | |
51 | * of the exceptions info is indicated by an exception with a | |
52 | * new_chunk of 0, which is invalid since it would point to the | |
53 | * header chunk. | |
54 | */ | |
55 | ||
56 | /* | |
57 | * Magic for persistent snapshots: "SnAp" - Feeble isn't it. | |
58 | */ | |
59 | #define SNAP_MAGIC 0x70416e53 | |
60 | ||
61 | /* | |
62 | * The on-disk version of the metadata. | |
63 | */ | |
64 | #define SNAPSHOT_DISK_VERSION 1 | |
65 | ||
4454a621 MP |
66 | #define NUM_SNAPSHOT_HDR_CHUNKS 1 |
67 | ||
4db6bfe0 | 68 | struct disk_header { |
283a8328 | 69 | __le32 magic; |
4db6bfe0 AK |
70 | |
71 | /* | |
72 | * Is this snapshot valid. There is no way of recovering | |
73 | * an invalid snapshot. | |
74 | */ | |
283a8328 | 75 | __le32 valid; |
4db6bfe0 AK |
76 | |
77 | /* | |
78 | * Simple, incrementing version. no backward | |
79 | * compatibility. | |
80 | */ | |
283a8328 | 81 | __le32 version; |
4db6bfe0 AK |
82 | |
83 | /* In sectors */ | |
283a8328 AK |
84 | __le32 chunk_size; |
85 | } __packed; | |
4db6bfe0 AK |
86 | |
87 | struct disk_exception { | |
283a8328 AK |
88 | __le64 old_chunk; |
89 | __le64 new_chunk; | |
90 | } __packed; | |
91 | ||
92 | struct core_exception { | |
4db6bfe0 AK |
93 | uint64_t old_chunk; |
94 | uint64_t new_chunk; | |
95 | }; | |
96 | ||
97 | struct commit_callback { | |
02f10ba1 | 98 | void (*callback)(void *ref, int success); |
4db6bfe0 AK |
99 | void *context; |
100 | }; | |
101 | ||
102 | /* | |
103 | * The top level structure for a persistent exception store. | |
104 | */ | |
105 | struct pstore { | |
71fab00a | 106 | struct dm_exception_store *store; |
4db6bfe0 AK |
107 | int version; |
108 | int valid; | |
109 | uint32_t exceptions_per_area; | |
110 | ||
111 | /* | |
112 | * Now that we have an asynchronous kcopyd there is no | |
113 | * need for large chunk sizes, so it wont hurt to have a | |
114 | * whole chunks worth of metadata in memory at once. | |
115 | */ | |
116 | void *area; | |
117 | ||
118 | /* | |
119 | * An area of zeros used to clear the next area. | |
120 | */ | |
121 | void *zero_area; | |
122 | ||
61578dcd MP |
123 | /* |
124 | * An area used for header. The header can be written | |
125 | * concurrently with metadata (when invalidating the snapshot), | |
126 | * so it needs a separate buffer. | |
127 | */ | |
128 | void *header_area; | |
129 | ||
4db6bfe0 AK |
130 | /* |
131 | * Used to keep track of which metadata area the data in | |
132 | * 'chunk' refers to. | |
133 | */ | |
134 | chunk_t current_area; | |
135 | ||
136 | /* | |
137 | * The next free chunk for an exception. | |
4454a621 MP |
138 | * |
139 | * When creating exceptions, all the chunks here and above are | |
140 | * free. It holds the next chunk to be allocated. On rare | |
141 | * occasions (e.g. after a system crash) holes can be left in | |
142 | * the exception store because chunks can be committed out of | |
143 | * order. | |
144 | * | |
145 | * When merging exceptions, it does not necessarily mean all the | |
146 | * chunks here and above are free. It holds the value it would | |
147 | * have held if all chunks had been committed in order of | |
148 | * allocation. Consequently the value may occasionally be | |
149 | * slightly too low, but since it's only used for 'status' and | |
150 | * it can never reach its minimum value too early this doesn't | |
151 | * matter. | |
4db6bfe0 | 152 | */ |
4454a621 | 153 | |
4db6bfe0 AK |
154 | chunk_t next_free; |
155 | ||
156 | /* | |
157 | * The index of next free exception in the current | |
158 | * metadata area. | |
159 | */ | |
160 | uint32_t current_committed; | |
161 | ||
162 | atomic_t pending_count; | |
163 | uint32_t callback_count; | |
164 | struct commit_callback *callbacks; | |
165 | struct dm_io_client *io_client; | |
166 | ||
167 | struct workqueue_struct *metadata_wq; | |
168 | }; | |
169 | ||
4db6bfe0 AK |
170 | static int alloc_area(struct pstore *ps) |
171 | { | |
172 | int r = -ENOMEM; | |
173 | size_t len; | |
174 | ||
71fab00a | 175 | len = ps->store->chunk_size << SECTOR_SHIFT; |
4db6bfe0 AK |
176 | |
177 | /* | |
178 | * Allocate the chunk_size block of memory that will hold | |
179 | * a single metadata area. | |
180 | */ | |
181 | ps->area = vmalloc(len); | |
182 | if (!ps->area) | |
61578dcd | 183 | goto err_area; |
4db6bfe0 | 184 | |
e29e65aa | 185 | ps->zero_area = vzalloc(len); |
61578dcd MP |
186 | if (!ps->zero_area) |
187 | goto err_zero_area; | |
4db6bfe0 | 188 | |
61578dcd MP |
189 | ps->header_area = vmalloc(len); |
190 | if (!ps->header_area) | |
191 | goto err_header_area; | |
192 | ||
4db6bfe0 | 193 | return 0; |
61578dcd MP |
194 | |
195 | err_header_area: | |
196 | vfree(ps->zero_area); | |
197 | ||
198 | err_zero_area: | |
199 | vfree(ps->area); | |
200 | ||
201 | err_area: | |
202 | return r; | |
4db6bfe0 AK |
203 | } |
204 | ||
205 | static void free_area(struct pstore *ps) | |
206 | { | |
0c8f8632 | 207 | vfree(ps->area); |
4db6bfe0 | 208 | ps->area = NULL; |
0c8f8632 | 209 | vfree(ps->zero_area); |
4db6bfe0 | 210 | ps->zero_area = NULL; |
0c8f8632 | 211 | vfree(ps->header_area); |
61578dcd | 212 | ps->header_area = NULL; |
4db6bfe0 AK |
213 | } |
214 | ||
215 | struct mdata_req { | |
216 | struct dm_io_region *where; | |
217 | struct dm_io_request *io_req; | |
218 | struct work_struct work; | |
219 | int result; | |
220 | }; | |
221 | ||
222 | static void do_metadata(struct work_struct *work) | |
223 | { | |
224 | struct mdata_req *req = container_of(work, struct mdata_req, work); | |
225 | ||
226 | req->result = dm_io(req->io_req, 1, req->where, NULL); | |
227 | } | |
228 | ||
229 | /* | |
230 | * Read or write a chunk aligned and sized block of data from a device. | |
231 | */ | |
6b990139 BVA |
232 | static int chunk_io(struct pstore *ps, void *area, chunk_t chunk, blk_opf_t opf, |
233 | int metadata) | |
4db6bfe0 AK |
234 | { |
235 | struct dm_io_region where = { | |
fc56f6fb | 236 | .bdev = dm_snap_cow(ps->store->snap)->bdev, |
71fab00a JB |
237 | .sector = ps->store->chunk_size * chunk, |
238 | .count = ps->store->chunk_size, | |
4db6bfe0 AK |
239 | }; |
240 | struct dm_io_request io_req = { | |
6b990139 | 241 | .bi_opf = opf, |
4db6bfe0 | 242 | .mem.type = DM_IO_VMA, |
02d2fd31 | 243 | .mem.ptr.vma = area, |
4db6bfe0 AK |
244 | .client = ps->io_client, |
245 | .notify.fn = NULL, | |
246 | }; | |
247 | struct mdata_req req; | |
248 | ||
249 | if (!metadata) | |
250 | return dm_io(&io_req, 1, &where, NULL); | |
251 | ||
252 | req.where = &where; | |
253 | req.io_req = &io_req; | |
254 | ||
255 | /* | |
256 | * Issue the synchronous I/O from a different thread | |
ed00aabd | 257 | * to avoid submit_bio_noacct recursion. |
4db6bfe0 | 258 | */ |
ca1cab37 | 259 | INIT_WORK_ONSTACK(&req.work, do_metadata); |
4db6bfe0 | 260 | queue_work(ps->metadata_wq, &req.work); |
5ea330a7 | 261 | flush_workqueue(ps->metadata_wq); |
c1a64160 | 262 | destroy_work_on_stack(&req.work); |
4db6bfe0 AK |
263 | |
264 | return req.result; | |
265 | } | |
266 | ||
267 | /* | |
268 | * Convert a metadata area index to a chunk index. | |
269 | */ | |
270 | static chunk_t area_location(struct pstore *ps, chunk_t area) | |
271 | { | |
87c961cb | 272 | return NUM_SNAPSHOT_HDR_CHUNKS + ((ps->exceptions_per_area + 1) * area); |
4db6bfe0 AK |
273 | } |
274 | ||
e9c6a182 MP |
275 | static void skip_metadata(struct pstore *ps) |
276 | { | |
277 | uint32_t stride = ps->exceptions_per_area + 1; | |
278 | chunk_t next_free = ps->next_free; | |
0ef0b471 | 279 | |
e9c6a182 MP |
280 | if (sector_div(next_free, stride) == NUM_SNAPSHOT_HDR_CHUNKS) |
281 | ps->next_free++; | |
282 | } | |
283 | ||
4db6bfe0 AK |
284 | /* |
285 | * Read or write a metadata area. Remembering to skip the first | |
286 | * chunk which holds the header. | |
287 | */ | |
6b990139 | 288 | static int area_io(struct pstore *ps, blk_opf_t opf) |
4db6bfe0 | 289 | { |
7d837c0d | 290 | chunk_t chunk = area_location(ps, ps->current_area); |
4db6bfe0 | 291 | |
6b990139 | 292 | return chunk_io(ps, ps->area, chunk, opf, 0); |
4db6bfe0 AK |
293 | } |
294 | ||
295 | static void zero_memory_area(struct pstore *ps) | |
296 | { | |
71fab00a | 297 | memset(ps->area, 0, ps->store->chunk_size << SECTOR_SHIFT); |
4db6bfe0 AK |
298 | } |
299 | ||
300 | static int zero_disk_area(struct pstore *ps, chunk_t area) | |
301 | { | |
e6047149 | 302 | return chunk_io(ps, ps->zero_area, area_location(ps, area), |
6b990139 | 303 | REQ_OP_WRITE, 0); |
4db6bfe0 AK |
304 | } |
305 | ||
306 | static int read_header(struct pstore *ps, int *new_snapshot) | |
307 | { | |
308 | int r; | |
309 | struct disk_header *dh; | |
86a3238c | 310 | unsigned int chunk_size; |
4db6bfe0 | 311 | int chunk_size_supplied = 1; |
ae0b7448 | 312 | char *chunk_err; |
4db6bfe0 AK |
313 | |
314 | /* | |
df96eee6 MP |
315 | * Use default chunk size (or logical_block_size, if larger) |
316 | * if none supplied | |
4db6bfe0 | 317 | */ |
71fab00a JB |
318 | if (!ps->store->chunk_size) { |
319 | ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS, | |
fc56f6fb MS |
320 | bdev_logical_block_size(dm_snap_cow(ps->store->snap)-> |
321 | bdev) >> 9); | |
71fab00a | 322 | ps->store->chunk_mask = ps->store->chunk_size - 1; |
a3d939ae | 323 | ps->store->chunk_shift = __ffs(ps->store->chunk_size); |
4db6bfe0 AK |
324 | chunk_size_supplied = 0; |
325 | } | |
326 | ||
bda8efec | 327 | ps->io_client = dm_io_client_create(); |
4db6bfe0 AK |
328 | if (IS_ERR(ps->io_client)) |
329 | return PTR_ERR(ps->io_client); | |
330 | ||
331 | r = alloc_area(ps); | |
332 | if (r) | |
333 | return r; | |
334 | ||
6b990139 | 335 | r = chunk_io(ps, ps->header_area, 0, REQ_OP_READ, 1); |
4db6bfe0 AK |
336 | if (r) |
337 | goto bad; | |
338 | ||
61578dcd | 339 | dh = ps->header_area; |
4db6bfe0 AK |
340 | |
341 | if (le32_to_cpu(dh->magic) == 0) { | |
342 | *new_snapshot = 1; | |
343 | return 0; | |
344 | } | |
345 | ||
346 | if (le32_to_cpu(dh->magic) != SNAP_MAGIC) { | |
347 | DMWARN("Invalid or corrupt snapshot"); | |
348 | r = -ENXIO; | |
349 | goto bad; | |
350 | } | |
351 | ||
352 | *new_snapshot = 0; | |
353 | ps->valid = le32_to_cpu(dh->valid); | |
354 | ps->version = le32_to_cpu(dh->version); | |
355 | chunk_size = le32_to_cpu(dh->chunk_size); | |
356 | ||
ae0b7448 | 357 | if (ps->store->chunk_size == chunk_size) |
4db6bfe0 AK |
358 | return 0; |
359 | ||
ae0b7448 | 360 | if (chunk_size_supplied) |
2e84fecf | 361 | DMWARN("chunk size %u in device metadata overrides table chunk size of %u.", |
df96eee6 | 362 | chunk_size, ps->store->chunk_size); |
4db6bfe0 AK |
363 | |
364 | /* We had a bogus chunk_size. Fix stuff up. */ | |
365 | free_area(ps); | |
366 | ||
ae0b7448 MP |
367 | r = dm_exception_store_set_chunk_size(ps->store, chunk_size, |
368 | &chunk_err); | |
369 | if (r) { | |
df96eee6 MP |
370 | DMERR("invalid on-disk chunk size %u: %s.", |
371 | chunk_size, chunk_err); | |
ae0b7448 MP |
372 | return r; |
373 | } | |
4db6bfe0 | 374 | |
4db6bfe0 AK |
375 | r = alloc_area(ps); |
376 | return r; | |
377 | ||
378 | bad: | |
379 | free_area(ps); | |
380 | return r; | |
381 | } | |
382 | ||
383 | static int write_header(struct pstore *ps) | |
384 | { | |
385 | struct disk_header *dh; | |
386 | ||
61578dcd | 387 | memset(ps->header_area, 0, ps->store->chunk_size << SECTOR_SHIFT); |
4db6bfe0 | 388 | |
61578dcd | 389 | dh = ps->header_area; |
4db6bfe0 AK |
390 | dh->magic = cpu_to_le32(SNAP_MAGIC); |
391 | dh->valid = cpu_to_le32(ps->valid); | |
392 | dh->version = cpu_to_le32(ps->version); | |
71fab00a | 393 | dh->chunk_size = cpu_to_le32(ps->store->chunk_size); |
4db6bfe0 | 394 | |
6b990139 | 395 | return chunk_io(ps, ps->header_area, 0, REQ_OP_WRITE, 1); |
4db6bfe0 AK |
396 | } |
397 | ||
398 | /* | |
399 | * Access functions for the disk exceptions, these do the endian conversions. | |
400 | */ | |
2cadabd5 MP |
401 | static struct disk_exception *get_exception(struct pstore *ps, void *ps_area, |
402 | uint32_t index) | |
4db6bfe0 AK |
403 | { |
404 | BUG_ON(index >= ps->exceptions_per_area); | |
405 | ||
2cadabd5 | 406 | return ((struct disk_exception *) ps_area) + index; |
4db6bfe0 AK |
407 | } |
408 | ||
2cadabd5 | 409 | static void read_exception(struct pstore *ps, void *ps_area, |
283a8328 | 410 | uint32_t index, struct core_exception *result) |
4db6bfe0 | 411 | { |
2cadabd5 | 412 | struct disk_exception *de = get_exception(ps, ps_area, index); |
4db6bfe0 AK |
413 | |
414 | /* copy it */ | |
283a8328 AK |
415 | result->old_chunk = le64_to_cpu(de->old_chunk); |
416 | result->new_chunk = le64_to_cpu(de->new_chunk); | |
4db6bfe0 AK |
417 | } |
418 | ||
419 | static void write_exception(struct pstore *ps, | |
283a8328 | 420 | uint32_t index, struct core_exception *e) |
4db6bfe0 | 421 | { |
2cadabd5 | 422 | struct disk_exception *de = get_exception(ps, ps->area, index); |
4db6bfe0 AK |
423 | |
424 | /* copy it */ | |
283a8328 AK |
425 | de->old_chunk = cpu_to_le64(e->old_chunk); |
426 | de->new_chunk = cpu_to_le64(e->new_chunk); | |
4db6bfe0 AK |
427 | } |
428 | ||
4454a621 MP |
429 | static void clear_exception(struct pstore *ps, uint32_t index) |
430 | { | |
2cadabd5 | 431 | struct disk_exception *de = get_exception(ps, ps->area, index); |
4454a621 MP |
432 | |
433 | /* clear it */ | |
283a8328 AK |
434 | de->old_chunk = 0; |
435 | de->new_chunk = 0; | |
4454a621 MP |
436 | } |
437 | ||
4db6bfe0 AK |
438 | /* |
439 | * Registers the exceptions that are present in the current area. | |
440 | * 'full' is filled in to indicate if the area has been | |
441 | * filled. | |
442 | */ | |
2cadabd5 | 443 | static int insert_exceptions(struct pstore *ps, void *ps_area, |
a159c1ac JB |
444 | int (*callback)(void *callback_context, |
445 | chunk_t old, chunk_t new), | |
446 | void *callback_context, | |
447 | int *full) | |
4db6bfe0 AK |
448 | { |
449 | int r; | |
450 | unsigned int i; | |
283a8328 | 451 | struct core_exception e; |
4db6bfe0 AK |
452 | |
453 | /* presume the area is full */ | |
454 | *full = 1; | |
455 | ||
456 | for (i = 0; i < ps->exceptions_per_area; i++) { | |
2cadabd5 | 457 | read_exception(ps, ps_area, i, &e); |
4db6bfe0 AK |
458 | |
459 | /* | |
460 | * If the new_chunk is pointing at the start of | |
461 | * the COW device, where the first metadata area | |
462 | * is we know that we've hit the end of the | |
463 | * exceptions. Therefore the area is not full. | |
464 | */ | |
283a8328 | 465 | if (e.new_chunk == 0LL) { |
4db6bfe0 AK |
466 | ps->current_committed = i; |
467 | *full = 0; | |
468 | break; | |
469 | } | |
470 | ||
471 | /* | |
472 | * Keep track of the start of the free chunks. | |
473 | */ | |
283a8328 AK |
474 | if (ps->next_free <= e.new_chunk) |
475 | ps->next_free = e.new_chunk + 1; | |
4db6bfe0 AK |
476 | |
477 | /* | |
478 | * Otherwise we add the exception to the snapshot. | |
479 | */ | |
283a8328 | 480 | r = callback(callback_context, e.old_chunk, e.new_chunk); |
4db6bfe0 AK |
481 | if (r) |
482 | return r; | |
483 | } | |
484 | ||
485 | return 0; | |
486 | } | |
487 | ||
a159c1ac JB |
488 | static int read_exceptions(struct pstore *ps, |
489 | int (*callback)(void *callback_context, chunk_t old, | |
490 | chunk_t new), | |
491 | void *callback_context) | |
4db6bfe0 AK |
492 | { |
493 | int r, full = 1; | |
55494bf2 | 494 | struct dm_bufio_client *client; |
55b082e6 | 495 | chunk_t prefetch_area = 0; |
55494bf2 MP |
496 | |
497 | client = dm_bufio_client_create(dm_snap_cow(ps->store->snap)->bdev, | |
498 | ps->store->chunk_size << SECTOR_SHIFT, | |
0fcb100d | 499 | 1, 0, NULL, NULL, 0); |
55494bf2 MP |
500 | |
501 | if (IS_ERR(client)) | |
502 | return PTR_ERR(client); | |
4db6bfe0 | 503 | |
55b082e6 MP |
504 | /* |
505 | * Setup for one current buffer + desired readahead buffers. | |
506 | */ | |
507 | dm_bufio_set_minimum_buffers(client, 1 + DM_PREFETCH_CHUNKS); | |
508 | ||
4db6bfe0 AK |
509 | /* |
510 | * Keeping reading chunks and inserting exceptions until | |
511 | * we find a partially full area. | |
512 | */ | |
513 | for (ps->current_area = 0; full; ps->current_area++) { | |
55494bf2 MP |
514 | struct dm_buffer *bp; |
515 | void *area; | |
55b082e6 MP |
516 | chunk_t chunk; |
517 | ||
518 | if (unlikely(prefetch_area < ps->current_area)) | |
519 | prefetch_area = ps->current_area; | |
520 | ||
03b18887 HM |
521 | if (DM_PREFETCH_CHUNKS) { |
522 | do { | |
523 | chunk_t pf_chunk = area_location(ps, prefetch_area); | |
0ef0b471 | 524 | |
03b18887 HM |
525 | if (unlikely(pf_chunk >= dm_bufio_get_device_size(client))) |
526 | break; | |
527 | dm_bufio_prefetch(client, pf_chunk, 1); | |
528 | prefetch_area++; | |
529 | if (unlikely(!prefetch_area)) | |
530 | break; | |
531 | } while (prefetch_area <= ps->current_area + DM_PREFETCH_CHUNKS); | |
532 | } | |
55b082e6 MP |
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 | { | |
26cb62a2 | 570 | return store->context; |
4db6bfe0 AK |
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 */ | |
7a35693a | 604 | kvfree(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 | 613 | { |
3f649ab7 | 614 | int r, new_snapshot; |
4db6bfe0 AK |
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); | |
7a35693a MWO |
629 | ps->callbacks = kvcalloc(ps->exceptions_per_area, |
630 | sizeof(*ps->callbacks), GFP_KERNEL); | |
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, |
385277bf | 698 | struct dm_exception *e, int valid, |
8ca817c4 | 699 | void (*callback)(void *, int success), |
a159c1ac | 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 | ||
385277bf MP |
707 | if (!valid) |
708 | ps->valid = 0; | |
709 | ||
283a8328 AK |
710 | ce.old_chunk = e->old_chunk; |
711 | ce.new_chunk = e->new_chunk; | |
712 | write_exception(ps, ps->current_committed++, &ce); | |
4db6bfe0 AK |
713 | |
714 | /* | |
715 | * Add the callback to the back of the array. This code | |
716 | * is the only place where the callback array is | |
717 | * manipulated, and we know that it will never be called | |
718 | * multiple times concurrently. | |
719 | */ | |
720 | cb = ps->callbacks + ps->callback_count++; | |
721 | cb->callback = callback; | |
722 | cb->context = callback_context; | |
723 | ||
724 | /* | |
725 | * If there are exceptions in flight and we have not yet | |
726 | * filled this metadata area there's nothing more to do. | |
727 | */ | |
728 | if (!atomic_dec_and_test(&ps->pending_count) && | |
729 | (ps->current_committed != ps->exceptions_per_area)) | |
730 | return; | |
731 | ||
732 | /* | |
733 | * If we completely filled the current area, then wipe the next one. | |
734 | */ | |
735 | if ((ps->current_committed == ps->exceptions_per_area) && | |
a2d2b034 | 736 | zero_disk_area(ps, ps->current_area + 1)) |
4db6bfe0 AK |
737 | ps->valid = 0; |
738 | ||
739 | /* | |
740 | * Commit exceptions to disk. | |
741 | */ | |
6b990139 BVA |
742 | if (ps->valid && area_io(ps, REQ_OP_WRITE | REQ_PREFLUSH | REQ_FUA | |
743 | REQ_SYNC)) | |
4db6bfe0 AK |
744 | ps->valid = 0; |
745 | ||
746 | /* | |
747 | * Advance to the next area if this one is full. | |
748 | */ | |
749 | if (ps->current_committed == ps->exceptions_per_area) { | |
750 | ps->current_committed = 0; | |
751 | ps->current_area++; | |
752 | zero_memory_area(ps); | |
753 | } | |
754 | ||
755 | for (i = 0; i < ps->callback_count; i++) { | |
756 | cb = ps->callbacks + i; | |
757 | cb->callback(cb->context, ps->valid); | |
758 | } | |
759 | ||
760 | ps->callback_count = 0; | |
761 | } | |
762 | ||
4454a621 MP |
763 | static int persistent_prepare_merge(struct dm_exception_store *store, |
764 | chunk_t *last_old_chunk, | |
765 | chunk_t *last_new_chunk) | |
766 | { | |
767 | struct pstore *ps = get_info(store); | |
283a8328 | 768 | struct core_exception ce; |
4454a621 MP |
769 | int nr_consecutive; |
770 | int r; | |
771 | ||
772 | /* | |
773 | * When current area is empty, move back to preceding area. | |
774 | */ | |
775 | if (!ps->current_committed) { | |
776 | /* | |
777 | * Have we finished? | |
778 | */ | |
779 | if (!ps->current_area) | |
780 | return 0; | |
781 | ||
782 | ps->current_area--; | |
6b990139 | 783 | r = area_io(ps, REQ_OP_READ); |
4454a621 MP |
784 | if (r < 0) |
785 | return r; | |
786 | ps->current_committed = ps->exceptions_per_area; | |
787 | } | |
788 | ||
2cadabd5 | 789 | read_exception(ps, ps->area, ps->current_committed - 1, &ce); |
283a8328 AK |
790 | *last_old_chunk = ce.old_chunk; |
791 | *last_new_chunk = ce.new_chunk; | |
4454a621 MP |
792 | |
793 | /* | |
794 | * Find number of consecutive chunks within the current area, | |
795 | * working backwards. | |
796 | */ | |
797 | for (nr_consecutive = 1; nr_consecutive < ps->current_committed; | |
798 | nr_consecutive++) { | |
2cadabd5 MP |
799 | read_exception(ps, ps->area, |
800 | ps->current_committed - 1 - nr_consecutive, &ce); | |
283a8328 AK |
801 | if (ce.old_chunk != *last_old_chunk - nr_consecutive || |
802 | ce.new_chunk != *last_new_chunk - nr_consecutive) | |
4454a621 MP |
803 | break; |
804 | } | |
805 | ||
806 | return nr_consecutive; | |
807 | } | |
808 | ||
809 | static int persistent_commit_merge(struct dm_exception_store *store, | |
810 | int nr_merged) | |
811 | { | |
812 | int r, i; | |
813 | struct pstore *ps = get_info(store); | |
814 | ||
815 | BUG_ON(nr_merged > ps->current_committed); | |
816 | ||
817 | for (i = 0; i < nr_merged; i++) | |
818 | clear_exception(ps, ps->current_committed - 1 - i); | |
819 | ||
6b990139 | 820 | r = area_io(ps, REQ_OP_WRITE | REQ_PREFLUSH | REQ_FUA); |
4454a621 MP |
821 | if (r < 0) |
822 | return r; | |
823 | ||
824 | ps->current_committed -= nr_merged; | |
825 | ||
826 | /* | |
827 | * At this stage, only persistent_usage() uses ps->next_free, so | |
828 | * we make no attempt to keep ps->next_free strictly accurate | |
829 | * as exceptions may have been committed out-of-order originally. | |
830 | * Once a snapshot has become merging, we set it to the value it | |
831 | * would have held had all the exceptions been committed in order. | |
832 | * | |
833 | * ps->current_area does not get reduced by prepare_merge() until | |
834 | * after commit_merge() has removed the nr_merged previous exceptions. | |
835 | */ | |
87c961cb TK |
836 | ps->next_free = area_location(ps, ps->current_area) + |
837 | ps->current_committed + 1; | |
4454a621 MP |
838 | |
839 | return 0; | |
840 | } | |
841 | ||
a159c1ac | 842 | static void persistent_drop_snapshot(struct dm_exception_store *store) |
4db6bfe0 AK |
843 | { |
844 | struct pstore *ps = get_info(store); | |
845 | ||
846 | ps->valid = 0; | |
847 | if (write_header(ps)) | |
848 | DMWARN("write header failed"); | |
849 | } | |
850 | ||
b0d3cc01 | 851 | static int persistent_ctr(struct dm_exception_store *store, char *options) |
4db6bfe0 AK |
852 | { |
853 | struct pstore *ps; | |
a2a678ed | 854 | int r; |
4db6bfe0 AK |
855 | |
856 | /* allocate the pstore */ | |
a32079ce | 857 | ps = kzalloc(sizeof(*ps), GFP_KERNEL); |
4db6bfe0 AK |
858 | if (!ps) |
859 | return -ENOMEM; | |
860 | ||
71fab00a | 861 | ps->store = store; |
4db6bfe0 AK |
862 | ps->valid = 1; |
863 | ps->version = SNAPSHOT_DISK_VERSION; | |
864 | ps->area = NULL; | |
61578dcd MP |
865 | ps->zero_area = NULL; |
866 | ps->header_area = NULL; | |
4454a621 | 867 | ps->next_free = NUM_SNAPSHOT_HDR_CHUNKS + 1; /* header and 1st area */ |
4db6bfe0 AK |
868 | ps->current_committed = 0; |
869 | ||
870 | ps->callback_count = 0; | |
871 | atomic_set(&ps->pending_count, 0); | |
872 | ps->callbacks = NULL; | |
873 | ||
239c8dd5 | 874 | ps->metadata_wq = alloc_workqueue("ksnaphd", WQ_MEM_RECLAIM, 0); |
4db6bfe0 | 875 | if (!ps->metadata_wq) { |
4db6bfe0 | 876 | DMERR("couldn't start header metadata update thread"); |
a2a678ed SM |
877 | r = -ENOMEM; |
878 | goto err_workqueue; | |
4db6bfe0 AK |
879 | } |
880 | ||
b0d3cc01 MS |
881 | if (options) { |
882 | char overflow = toupper(options[0]); | |
0ef0b471 | 883 | |
b0d3cc01 MS |
884 | if (overflow == 'O') |
885 | store->userspace_supports_overflow = true; | |
886 | else { | |
887 | DMERR("Unsupported persistent store option: %s", options); | |
a2a678ed SM |
888 | r = -EINVAL; |
889 | goto err_options; | |
b0d3cc01 MS |
890 | } |
891 | } | |
892 | ||
4db6bfe0 AK |
893 | store->context = ps; |
894 | ||
895 | return 0; | |
a2a678ed SM |
896 | |
897 | err_options: | |
898 | destroy_workqueue(ps->metadata_wq); | |
899 | err_workqueue: | |
900 | kfree(ps); | |
901 | ||
902 | return r; | |
4db6bfe0 AK |
903 | } |
904 | ||
86a3238c | 905 | static unsigned int persistent_status(struct dm_exception_store *store, |
1e302a92 | 906 | status_type_t status, char *result, |
86a3238c | 907 | unsigned int maxlen) |
493df71c | 908 | { |
86a3238c | 909 | unsigned int sz = 0; |
1e302a92 JB |
910 | |
911 | switch (status) { | |
912 | case STATUSTYPE_INFO: | |
913 | break; | |
914 | case STATUSTYPE_TABLE: | |
b0d3cc01 MS |
915 | DMEMIT(" %s %llu", store->userspace_supports_overflow ? "PO" : "P", |
916 | (unsigned long long)store->chunk_size); | |
8ec45662 TS |
917 | break; |
918 | case STATUSTYPE_IMA: | |
919 | *result = '\0'; | |
920 | break; | |
1e302a92 | 921 | } |
493df71c JB |
922 | |
923 | return sz; | |
924 | } | |
925 | ||
926 | static struct dm_exception_store_type _persistent_type = { | |
927 | .name = "persistent", | |
928 | .module = THIS_MODULE, | |
929 | .ctr = persistent_ctr, | |
930 | .dtr = persistent_dtr, | |
931 | .read_metadata = persistent_read_metadata, | |
932 | .prepare_exception = persistent_prepare_exception, | |
933 | .commit_exception = persistent_commit_exception, | |
4454a621 MP |
934 | .prepare_merge = persistent_prepare_merge, |
935 | .commit_merge = persistent_commit_merge, | |
493df71c | 936 | .drop_snapshot = persistent_drop_snapshot, |
985903bb | 937 | .usage = persistent_usage, |
493df71c JB |
938 | .status = persistent_status, |
939 | }; | |
940 | ||
941 | static struct dm_exception_store_type _persistent_compat_type = { | |
942 | .name = "P", | |
943 | .module = THIS_MODULE, | |
944 | .ctr = persistent_ctr, | |
945 | .dtr = persistent_dtr, | |
946 | .read_metadata = persistent_read_metadata, | |
947 | .prepare_exception = persistent_prepare_exception, | |
948 | .commit_exception = persistent_commit_exception, | |
4454a621 MP |
949 | .prepare_merge = persistent_prepare_merge, |
950 | .commit_merge = persistent_commit_merge, | |
493df71c | 951 | .drop_snapshot = persistent_drop_snapshot, |
985903bb | 952 | .usage = persistent_usage, |
493df71c JB |
953 | .status = persistent_status, |
954 | }; | |
955 | ||
4db6bfe0 AK |
956 | int dm_persistent_snapshot_init(void) |
957 | { | |
493df71c JB |
958 | int r; |
959 | ||
960 | r = dm_exception_store_type_register(&_persistent_type); | |
961 | if (r) { | |
962 | DMERR("Unable to register persistent exception store type"); | |
963 | return r; | |
964 | } | |
965 | ||
966 | r = dm_exception_store_type_register(&_persistent_compat_type); | |
967 | if (r) { | |
2e84fecf | 968 | DMERR("Unable to register old-style persistent exception store type"); |
493df71c JB |
969 | dm_exception_store_type_unregister(&_persistent_type); |
970 | return r; | |
971 | } | |
972 | ||
973 | return r; | |
4db6bfe0 AK |
974 | } |
975 | ||
976 | void dm_persistent_snapshot_exit(void) | |
977 | { | |
493df71c JB |
978 | dm_exception_store_type_unregister(&_persistent_type); |
979 | dm_exception_store_type_unregister(&_persistent_compat_type); | |
4db6bfe0 | 980 | } |