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Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +00001/*
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"
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +00009
10#include <linux/mm.h>
11#include <linux/pagemap.h>
12#include <linux/vmalloc.h>
13#include <linux/slab.h>
14#include <linux/dm-io.h>
15
16#define DM_MSG_PREFIX "persistent snapshot"
17#define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */
18
19/*-----------------------------------------------------------------
20 * Persistent snapshots, by persistent we mean that the snapshot
21 * will survive a reboot.
22 *---------------------------------------------------------------*/
23
24/*
25 * We need to store a record of which parts of the origin have
26 * been copied to the snapshot device. The snapshot code
27 * requires that we copy exception chunks to chunk aligned areas
28 * of the COW store. It makes sense therefore, to store the
29 * metadata in chunk size blocks.
30 *
31 * There is no backward or forward compatibility implemented,
32 * snapshots with different disk versions than the kernel will
33 * not be usable. It is expected that "lvcreate" will blank out
34 * the start of a fresh COW device before calling the snapshot
35 * constructor.
36 *
37 * The first chunk of the COW device just contains the header.
38 * After this there is a chunk filled with exception metadata,
39 * followed by as many exception chunks as can fit in the
40 * metadata areas.
41 *
42 * All on disk structures are in little-endian format. The end
43 * of the exceptions info is indicated by an exception with a
44 * new_chunk of 0, which is invalid since it would point to the
45 * header chunk.
46 */
47
48/*
49 * Magic for persistent snapshots: "SnAp" - Feeble isn't it.
50 */
51#define SNAP_MAGIC 0x70416e53
52
53/*
54 * The on-disk version of the metadata.
55 */
56#define SNAPSHOT_DISK_VERSION 1
57
58struct disk_header {
59 uint32_t magic;
60
61 /*
62 * Is this snapshot valid. There is no way of recovering
63 * an invalid snapshot.
64 */
65 uint32_t valid;
66
67 /*
68 * Simple, incrementing version. no backward
69 * compatibility.
70 */
71 uint32_t version;
72
73 /* In sectors */
74 uint32_t chunk_size;
75};
76
77struct disk_exception {
78 uint64_t old_chunk;
79 uint64_t new_chunk;
80};
81
82struct commit_callback {
83 void (*callback)(void *, int success);
84 void *context;
85};
86
87/*
88 * The top level structure for a persistent exception store.
89 */
90struct pstore {
Jonathan Brassow71fab002009-04-02 19:55:33 +010091 struct dm_exception_store *store;
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +000092 int version;
93 int valid;
94 uint32_t exceptions_per_area;
95
96 /*
97 * Now that we have an asynchronous kcopyd there is no
98 * need for large chunk sizes, so it wont hurt to have a
99 * whole chunks worth of metadata in memory at once.
100 */
101 void *area;
102
103 /*
104 * An area of zeros used to clear the next area.
105 */
106 void *zero_area;
107
108 /*
109 * Used to keep track of which metadata area the data in
110 * 'chunk' refers to.
111 */
112 chunk_t current_area;
113
114 /*
115 * The next free chunk for an exception.
116 */
117 chunk_t next_free;
118
119 /*
120 * The index of next free exception in the current
121 * metadata area.
122 */
123 uint32_t current_committed;
124
125 atomic_t pending_count;
126 uint32_t callback_count;
127 struct commit_callback *callbacks;
128 struct dm_io_client *io_client;
129
130 struct workqueue_struct *metadata_wq;
131};
132
133static unsigned sectors_to_pages(unsigned sectors)
134{
135 return DIV_ROUND_UP(sectors, PAGE_SIZE >> 9);
136}
137
138static int alloc_area(struct pstore *ps)
139{
140 int r = -ENOMEM;
141 size_t len;
142
Jonathan Brassow71fab002009-04-02 19:55:33 +0100143 len = ps->store->chunk_size << SECTOR_SHIFT;
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000144
145 /*
146 * Allocate the chunk_size block of memory that will hold
147 * a single metadata area.
148 */
149 ps->area = vmalloc(len);
150 if (!ps->area)
151 return r;
152
153 ps->zero_area = vmalloc(len);
154 if (!ps->zero_area) {
155 vfree(ps->area);
156 return r;
157 }
158 memset(ps->zero_area, 0, len);
159
160 return 0;
161}
162
163static void free_area(struct pstore *ps)
164{
Jonathan Brassowa32079c2009-04-02 19:55:35 +0100165 if (ps->area)
166 vfree(ps->area);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000167 ps->area = NULL;
Jonathan Brassowa32079c2009-04-02 19:55:35 +0100168
169 if (ps->zero_area)
170 vfree(ps->zero_area);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000171 ps->zero_area = NULL;
172}
173
174struct mdata_req {
175 struct dm_io_region *where;
176 struct dm_io_request *io_req;
177 struct work_struct work;
178 int result;
179};
180
181static void do_metadata(struct work_struct *work)
182{
183 struct mdata_req *req = container_of(work, struct mdata_req, work);
184
185 req->result = dm_io(req->io_req, 1, req->where, NULL);
186}
187
188/*
189 * Read or write a chunk aligned and sized block of data from a device.
190 */
191static int chunk_io(struct pstore *ps, chunk_t chunk, int rw, int metadata)
192{
193 struct dm_io_region where = {
Jonathan Brassow71fab002009-04-02 19:55:33 +0100194 .bdev = ps->store->cow->bdev,
195 .sector = ps->store->chunk_size * chunk,
196 .count = ps->store->chunk_size,
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000197 };
198 struct dm_io_request io_req = {
199 .bi_rw = rw,
200 .mem.type = DM_IO_VMA,
201 .mem.ptr.vma = ps->area,
202 .client = ps->io_client,
203 .notify.fn = NULL,
204 };
205 struct mdata_req req;
206
207 if (!metadata)
208 return dm_io(&io_req, 1, &where, NULL);
209
210 req.where = &where;
211 req.io_req = &io_req;
212
213 /*
214 * Issue the synchronous I/O from a different thread
215 * to avoid generic_make_request recursion.
216 */
217 INIT_WORK(&req.work, do_metadata);
218 queue_work(ps->metadata_wq, &req.work);
219 flush_workqueue(ps->metadata_wq);
220
221 return req.result;
222}
223
224/*
225 * Convert a metadata area index to a chunk index.
226 */
227static chunk_t area_location(struct pstore *ps, chunk_t area)
228{
229 return 1 + ((ps->exceptions_per_area + 1) * area);
230}
231
232/*
233 * Read or write a metadata area. Remembering to skip the first
234 * chunk which holds the header.
235 */
236static int area_io(struct pstore *ps, int rw)
237{
238 int r;
239 chunk_t chunk;
240
241 chunk = area_location(ps, ps->current_area);
242
243 r = chunk_io(ps, chunk, rw, 0);
244 if (r)
245 return r;
246
247 return 0;
248}
249
250static void zero_memory_area(struct pstore *ps)
251{
Jonathan Brassow71fab002009-04-02 19:55:33 +0100252 memset(ps->area, 0, ps->store->chunk_size << SECTOR_SHIFT);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000253}
254
255static int zero_disk_area(struct pstore *ps, chunk_t area)
256{
257 struct dm_io_region where = {
Jonathan Brassow71fab002009-04-02 19:55:33 +0100258 .bdev = ps->store->cow->bdev,
259 .sector = ps->store->chunk_size * area_location(ps, area),
260 .count = ps->store->chunk_size,
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000261 };
262 struct dm_io_request io_req = {
263 .bi_rw = WRITE,
264 .mem.type = DM_IO_VMA,
265 .mem.ptr.vma = ps->zero_area,
266 .client = ps->io_client,
267 .notify.fn = NULL,
268 };
269
270 return dm_io(&io_req, 1, &where, NULL);
271}
272
273static int read_header(struct pstore *ps, int *new_snapshot)
274{
275 int r;
276 struct disk_header *dh;
277 chunk_t chunk_size;
278 int chunk_size_supplied = 1;
279
280 /*
281 * Use default chunk size (or hardsect_size, if larger) if none supplied
282 */
Jonathan Brassow71fab002009-04-02 19:55:33 +0100283 if (!ps->store->chunk_size) {
284 ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS,
Martin K. Petersene1defc42009-05-22 17:17:49 -0400285 bdev_logical_block_size(ps->store->cow->bdev) >> 9);
Jonathan Brassow71fab002009-04-02 19:55:33 +0100286 ps->store->chunk_mask = ps->store->chunk_size - 1;
287 ps->store->chunk_shift = ffs(ps->store->chunk_size) - 1;
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000288 chunk_size_supplied = 0;
289 }
290
Jonathan Brassow71fab002009-04-02 19:55:33 +0100291 ps->io_client = dm_io_client_create(sectors_to_pages(ps->store->
292 chunk_size));
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000293 if (IS_ERR(ps->io_client))
294 return PTR_ERR(ps->io_client);
295
296 r = alloc_area(ps);
297 if (r)
298 return r;
299
300 r = chunk_io(ps, 0, READ, 1);
301 if (r)
302 goto bad;
303
304 dh = (struct disk_header *) ps->area;
305
306 if (le32_to_cpu(dh->magic) == 0) {
307 *new_snapshot = 1;
308 return 0;
309 }
310
311 if (le32_to_cpu(dh->magic) != SNAP_MAGIC) {
312 DMWARN("Invalid or corrupt snapshot");
313 r = -ENXIO;
314 goto bad;
315 }
316
317 *new_snapshot = 0;
318 ps->valid = le32_to_cpu(dh->valid);
319 ps->version = le32_to_cpu(dh->version);
320 chunk_size = le32_to_cpu(dh->chunk_size);
321
Jonathan Brassow71fab002009-04-02 19:55:33 +0100322 if (!chunk_size_supplied || ps->store->chunk_size == chunk_size)
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000323 return 0;
324
325 DMWARN("chunk size %llu in device metadata overrides "
326 "table chunk size of %llu.",
327 (unsigned long long)chunk_size,
Jonathan Brassow71fab002009-04-02 19:55:33 +0100328 (unsigned long long)ps->store->chunk_size);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000329
330 /* We had a bogus chunk_size. Fix stuff up. */
331 free_area(ps);
332
Jonathan Brassow71fab002009-04-02 19:55:33 +0100333 ps->store->chunk_size = chunk_size;
334 ps->store->chunk_mask = chunk_size - 1;
335 ps->store->chunk_shift = ffs(chunk_size) - 1;
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000336
Jonathan Brassow71fab002009-04-02 19:55:33 +0100337 r = dm_io_client_resize(sectors_to_pages(ps->store->chunk_size),
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000338 ps->io_client);
339 if (r)
340 return r;
341
342 r = alloc_area(ps);
343 return r;
344
345bad:
346 free_area(ps);
347 return r;
348}
349
350static int write_header(struct pstore *ps)
351{
352 struct disk_header *dh;
353
Jonathan Brassow71fab002009-04-02 19:55:33 +0100354 memset(ps->area, 0, ps->store->chunk_size << SECTOR_SHIFT);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000355
356 dh = (struct disk_header *) ps->area;
357 dh->magic = cpu_to_le32(SNAP_MAGIC);
358 dh->valid = cpu_to_le32(ps->valid);
359 dh->version = cpu_to_le32(ps->version);
Jonathan Brassow71fab002009-04-02 19:55:33 +0100360 dh->chunk_size = cpu_to_le32(ps->store->chunk_size);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000361
362 return chunk_io(ps, 0, WRITE, 1);
363}
364
365/*
366 * Access functions for the disk exceptions, these do the endian conversions.
367 */
368static struct disk_exception *get_exception(struct pstore *ps, uint32_t index)
369{
370 BUG_ON(index >= ps->exceptions_per_area);
371
372 return ((struct disk_exception *) ps->area) + index;
373}
374
375static void read_exception(struct pstore *ps,
376 uint32_t index, struct disk_exception *result)
377{
378 struct disk_exception *e = get_exception(ps, index);
379
380 /* copy it */
381 result->old_chunk = le64_to_cpu(e->old_chunk);
382 result->new_chunk = le64_to_cpu(e->new_chunk);
383}
384
385static void write_exception(struct pstore *ps,
386 uint32_t index, struct disk_exception *de)
387{
388 struct disk_exception *e = get_exception(ps, index);
389
390 /* copy it */
391 e->old_chunk = cpu_to_le64(de->old_chunk);
392 e->new_chunk = cpu_to_le64(de->new_chunk);
393}
394
395/*
396 * Registers the exceptions that are present in the current area.
397 * 'full' is filled in to indicate if the area has been
398 * filled.
399 */
Jonathan Brassowa159c1a2009-01-06 03:05:19 +0000400static int insert_exceptions(struct pstore *ps,
401 int (*callback)(void *callback_context,
402 chunk_t old, chunk_t new),
403 void *callback_context,
404 int *full)
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000405{
406 int r;
407 unsigned int i;
408 struct disk_exception de;
409
410 /* presume the area is full */
411 *full = 1;
412
413 for (i = 0; i < ps->exceptions_per_area; i++) {
414 read_exception(ps, i, &de);
415
416 /*
417 * If the new_chunk is pointing at the start of
418 * the COW device, where the first metadata area
419 * is we know that we've hit the end of the
420 * exceptions. Therefore the area is not full.
421 */
422 if (de.new_chunk == 0LL) {
423 ps->current_committed = i;
424 *full = 0;
425 break;
426 }
427
428 /*
429 * Keep track of the start of the free chunks.
430 */
431 if (ps->next_free <= de.new_chunk)
432 ps->next_free = de.new_chunk + 1;
433
434 /*
435 * Otherwise we add the exception to the snapshot.
436 */
Jonathan Brassowa159c1a2009-01-06 03:05:19 +0000437 r = callback(callback_context, de.old_chunk, de.new_chunk);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000438 if (r)
439 return r;
440 }
441
442 return 0;
443}
444
Jonathan Brassowa159c1a2009-01-06 03:05:19 +0000445static int read_exceptions(struct pstore *ps,
446 int (*callback)(void *callback_context, chunk_t old,
447 chunk_t new),
448 void *callback_context)
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000449{
450 int r, full = 1;
451
452 /*
453 * Keeping reading chunks and inserting exceptions until
454 * we find a partially full area.
455 */
456 for (ps->current_area = 0; full; ps->current_area++) {
457 r = area_io(ps, READ);
458 if (r)
459 return r;
460
Jonathan Brassowa159c1a2009-01-06 03:05:19 +0000461 r = insert_exceptions(ps, callback, callback_context, &full);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000462 if (r)
463 return r;
464 }
465
466 ps->current_area--;
467
468 return 0;
469}
470
471static struct pstore *get_info(struct dm_exception_store *store)
472{
473 return (struct pstore *) store->context;
474}
475
476static void persistent_fraction_full(struct dm_exception_store *store,
477 sector_t *numerator, sector_t *denominator)
478{
Jonathan Brassowd0216842009-04-02 19:55:32 +0100479 *numerator = get_info(store)->next_free * store->chunk_size;
Jonathan Brassow49beb2b2009-04-02 19:55:33 +0100480 *denominator = get_dev_size(store->cow->bdev);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000481}
482
Jonathan Brassow493df712009-04-02 19:55:31 +0100483static void persistent_dtr(struct dm_exception_store *store)
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000484{
485 struct pstore *ps = get_info(store);
486
487 destroy_workqueue(ps->metadata_wq);
Jonathan Brassowa32079c2009-04-02 19:55:35 +0100488
489 /* Created in read_header */
490 if (ps->io_client)
491 dm_io_client_destroy(ps->io_client);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000492 free_area(ps);
Jonathan Brassowa32079c2009-04-02 19:55:35 +0100493
494 /* Allocated in persistent_read_metadata */
495 if (ps->callbacks)
496 vfree(ps->callbacks);
497
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000498 kfree(ps);
499}
500
Jonathan Brassowa159c1a2009-01-06 03:05:19 +0000501static int persistent_read_metadata(struct dm_exception_store *store,
502 int (*callback)(void *callback_context,
503 chunk_t old, chunk_t new),
504 void *callback_context)
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000505{
506 int r, uninitialized_var(new_snapshot);
507 struct pstore *ps = get_info(store);
508
509 /*
510 * Read the snapshot header.
511 */
512 r = read_header(ps, &new_snapshot);
513 if (r)
514 return r;
515
516 /*
517 * Now we know correct chunk_size, complete the initialisation.
518 */
Jonathan Brassow71fab002009-04-02 19:55:33 +0100519 ps->exceptions_per_area = (ps->store->chunk_size << SECTOR_SHIFT) /
520 sizeof(struct disk_exception);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000521 ps->callbacks = dm_vcalloc(ps->exceptions_per_area,
522 sizeof(*ps->callbacks));
523 if (!ps->callbacks)
524 return -ENOMEM;
525
526 /*
527 * Do we need to setup a new snapshot ?
528 */
529 if (new_snapshot) {
530 r = write_header(ps);
531 if (r) {
532 DMWARN("write_header failed");
533 return r;
534 }
535
536 ps->current_area = 0;
537 zero_memory_area(ps);
538 r = zero_disk_area(ps, 0);
539 if (r) {
540 DMWARN("zero_disk_area(0) failed");
541 return r;
542 }
543 } else {
544 /*
545 * Sanity checks.
546 */
547 if (ps->version != SNAPSHOT_DISK_VERSION) {
548 DMWARN("unable to handle snapshot disk version %d",
549 ps->version);
550 return -EINVAL;
551 }
552
553 /*
554 * Metadata are valid, but snapshot is invalidated
555 */
556 if (!ps->valid)
557 return 1;
558
559 /*
560 * Read the metadata.
561 */
Jonathan Brassowa159c1a2009-01-06 03:05:19 +0000562 r = read_exceptions(ps, callback, callback_context);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000563 if (r)
564 return r;
565 }
566
567 return 0;
568}
569
Jonathan Brassowa159c1a2009-01-06 03:05:19 +0000570static int persistent_prepare_exception(struct dm_exception_store *store,
571 struct dm_snap_exception *e)
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000572{
573 struct pstore *ps = get_info(store);
574 uint32_t stride;
575 chunk_t next_free;
Jonathan Brassow49beb2b2009-04-02 19:55:33 +0100576 sector_t size = get_dev_size(store->cow->bdev);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000577
578 /* Is there enough room ? */
Jonathan Brassowd0216842009-04-02 19:55:32 +0100579 if (size < ((ps->next_free + 1) * store->chunk_size))
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000580 return -ENOSPC;
581
582 e->new_chunk = ps->next_free;
583
584 /*
585 * Move onto the next free pending, making sure to take
586 * into account the location of the metadata chunks.
587 */
588 stride = (ps->exceptions_per_area + 1);
589 next_free = ++ps->next_free;
590 if (sector_div(next_free, stride) == 1)
591 ps->next_free++;
592
593 atomic_inc(&ps->pending_count);
594 return 0;
595}
596
Jonathan Brassowa159c1a2009-01-06 03:05:19 +0000597static void persistent_commit_exception(struct dm_exception_store *store,
598 struct dm_snap_exception *e,
599 void (*callback) (void *, int success),
600 void *callback_context)
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000601{
602 unsigned int i;
603 struct pstore *ps = get_info(store);
604 struct disk_exception de;
605 struct commit_callback *cb;
606
607 de.old_chunk = e->old_chunk;
608 de.new_chunk = e->new_chunk;
609 write_exception(ps, ps->current_committed++, &de);
610
611 /*
612 * Add the callback to the back of the array. This code
613 * is the only place where the callback array is
614 * manipulated, and we know that it will never be called
615 * multiple times concurrently.
616 */
617 cb = ps->callbacks + ps->callback_count++;
618 cb->callback = callback;
619 cb->context = callback_context;
620
621 /*
622 * If there are exceptions in flight and we have not yet
623 * filled this metadata area there's nothing more to do.
624 */
625 if (!atomic_dec_and_test(&ps->pending_count) &&
626 (ps->current_committed != ps->exceptions_per_area))
627 return;
628
629 /*
630 * If we completely filled the current area, then wipe the next one.
631 */
632 if ((ps->current_committed == ps->exceptions_per_area) &&
633 zero_disk_area(ps, ps->current_area + 1))
634 ps->valid = 0;
635
636 /*
637 * Commit exceptions to disk.
638 */
Mikulas Patocka2bd02342009-06-22 10:12:26 +0100639 if (ps->valid && area_io(ps, WRITE_BARRIER))
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000640 ps->valid = 0;
641
642 /*
643 * Advance to the next area if this one is full.
644 */
645 if (ps->current_committed == ps->exceptions_per_area) {
646 ps->current_committed = 0;
647 ps->current_area++;
648 zero_memory_area(ps);
649 }
650
651 for (i = 0; i < ps->callback_count; i++) {
652 cb = ps->callbacks + i;
653 cb->callback(cb->context, ps->valid);
654 }
655
656 ps->callback_count = 0;
657}
658
Jonathan Brassowa159c1a2009-01-06 03:05:19 +0000659static void persistent_drop_snapshot(struct dm_exception_store *store)
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000660{
661 struct pstore *ps = get_info(store);
662
663 ps->valid = 0;
664 if (write_header(ps))
665 DMWARN("write header failed");
666}
667
Jonathan Brassow493df712009-04-02 19:55:31 +0100668static int persistent_ctr(struct dm_exception_store *store,
669 unsigned argc, char **argv)
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000670{
671 struct pstore *ps;
672
673 /* allocate the pstore */
Jonathan Brassowa32079c2009-04-02 19:55:35 +0100674 ps = kzalloc(sizeof(*ps), GFP_KERNEL);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000675 if (!ps)
676 return -ENOMEM;
677
Jonathan Brassow71fab002009-04-02 19:55:33 +0100678 ps->store = store;
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000679 ps->valid = 1;
680 ps->version = SNAPSHOT_DISK_VERSION;
681 ps->area = NULL;
682 ps->next_free = 2; /* skipping the header and first area */
683 ps->current_committed = 0;
684
685 ps->callback_count = 0;
686 atomic_set(&ps->pending_count, 0);
687 ps->callbacks = NULL;
688
689 ps->metadata_wq = create_singlethread_workqueue("ksnaphd");
690 if (!ps->metadata_wq) {
691 kfree(ps);
692 DMERR("couldn't start header metadata update thread");
693 return -ENOMEM;
694 }
695
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000696 store->context = ps;
697
698 return 0;
699}
700
Jonathan Brassow1e302a92009-04-02 19:55:35 +0100701static unsigned persistent_status(struct dm_exception_store *store,
702 status_type_t status, char *result,
703 unsigned maxlen)
Jonathan Brassow493df712009-04-02 19:55:31 +0100704{
Jonathan Brassow1e302a92009-04-02 19:55:35 +0100705 unsigned sz = 0;
706
707 switch (status) {
708 case STATUSTYPE_INFO:
709 break;
710 case STATUSTYPE_TABLE:
711 DMEMIT(" %s P %llu", store->cow->name,
712 (unsigned long long)store->chunk_size);
713 }
Jonathan Brassow493df712009-04-02 19:55:31 +0100714
715 return sz;
716}
717
718static struct dm_exception_store_type _persistent_type = {
719 .name = "persistent",
720 .module = THIS_MODULE,
721 .ctr = persistent_ctr,
722 .dtr = persistent_dtr,
723 .read_metadata = persistent_read_metadata,
724 .prepare_exception = persistent_prepare_exception,
725 .commit_exception = persistent_commit_exception,
726 .drop_snapshot = persistent_drop_snapshot,
727 .fraction_full = persistent_fraction_full,
728 .status = persistent_status,
729};
730
731static struct dm_exception_store_type _persistent_compat_type = {
732 .name = "P",
733 .module = THIS_MODULE,
734 .ctr = persistent_ctr,
735 .dtr = persistent_dtr,
736 .read_metadata = persistent_read_metadata,
737 .prepare_exception = persistent_prepare_exception,
738 .commit_exception = persistent_commit_exception,
739 .drop_snapshot = persistent_drop_snapshot,
740 .fraction_full = persistent_fraction_full,
741 .status = persistent_status,
742};
743
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000744int dm_persistent_snapshot_init(void)
745{
Jonathan Brassow493df712009-04-02 19:55:31 +0100746 int r;
747
748 r = dm_exception_store_type_register(&_persistent_type);
749 if (r) {
750 DMERR("Unable to register persistent exception store type");
751 return r;
752 }
753
754 r = dm_exception_store_type_register(&_persistent_compat_type);
755 if (r) {
756 DMERR("Unable to register old-style persistent exception "
757 "store type");
758 dm_exception_store_type_unregister(&_persistent_type);
759 return r;
760 }
761
762 return r;
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000763}
764
765void dm_persistent_snapshot_exit(void)
766{
Jonathan Brassow493df712009-04-02 19:55:31 +0100767 dm_exception_store_type_unregister(&_persistent_type);
768 dm_exception_store_type_unregister(&_persistent_compat_type);
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000769}