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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * dm-snapshot.c | |
3 | * | |
4 | * Copyright (C) 2001-2002 Sistina Software (UK) Limited. | |
5 | * | |
6 | * This file is released under the GPL. | |
7 | */ | |
8 | ||
9 | #include <linux/blkdev.h> | |
1da177e4 | 10 | #include <linux/device-mapper.h> |
90fa1527 | 11 | #include <linux/delay.h> |
1da177e4 LT |
12 | #include <linux/fs.h> |
13 | #include <linux/init.h> | |
14 | #include <linux/kdev_t.h> | |
15 | #include <linux/list.h> | |
16 | #include <linux/mempool.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/slab.h> | |
19 | #include <linux/vmalloc.h> | |
6f3c3f0a | 20 | #include <linux/log2.h> |
a765e20e | 21 | #include <linux/dm-kcopyd.h> |
ccc45ea8 | 22 | #include <linux/workqueue.h> |
1da177e4 | 23 | |
aea53d92 | 24 | #include "dm-exception-store.h" |
1da177e4 | 25 | |
72d94861 AK |
26 | #define DM_MSG_PREFIX "snapshots" |
27 | ||
d698aa45 MP |
28 | static const char dm_snapshot_merge_target_name[] = "snapshot-merge"; |
29 | ||
30 | #define dm_target_is_snapshot_merge(ti) \ | |
31 | ((ti)->type->name == dm_snapshot_merge_target_name) | |
32 | ||
1da177e4 LT |
33 | /* |
34 | * The percentage increment we will wake up users at | |
35 | */ | |
36 | #define WAKE_UP_PERCENT 5 | |
37 | ||
38 | /* | |
39 | * kcopyd priority of snapshot operations | |
40 | */ | |
41 | #define SNAPSHOT_COPY_PRIORITY 2 | |
42 | ||
43 | /* | |
8ee2767a | 44 | * Reserve 1MB for each snapshot initially (with minimum of 1 page). |
1da177e4 | 45 | */ |
8ee2767a | 46 | #define SNAPSHOT_PAGES (((1UL << 20) >> PAGE_SHIFT) ? : 1) |
1da177e4 | 47 | |
cd45daff MP |
48 | /* |
49 | * The size of the mempool used to track chunks in use. | |
50 | */ | |
51 | #define MIN_IOS 256 | |
52 | ||
ccc45ea8 JB |
53 | #define DM_TRACKED_CHUNK_HASH_SIZE 16 |
54 | #define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ | |
55 | (DM_TRACKED_CHUNK_HASH_SIZE - 1)) | |
56 | ||
191437a5 | 57 | struct dm_exception_table { |
ccc45ea8 JB |
58 | uint32_t hash_mask; |
59 | unsigned hash_shift; | |
60 | struct list_head *table; | |
61 | }; | |
62 | ||
63 | struct dm_snapshot { | |
64 | struct rw_semaphore lock; | |
65 | ||
66 | struct dm_dev *origin; | |
fc56f6fb MS |
67 | struct dm_dev *cow; |
68 | ||
69 | struct dm_target *ti; | |
ccc45ea8 JB |
70 | |
71 | /* List of snapshots per Origin */ | |
72 | struct list_head list; | |
73 | ||
74 | /* You can't use a snapshot if this is 0 (e.g. if full) */ | |
75 | int valid; | |
76 | ||
77 | /* Origin writes don't trigger exceptions until this is set */ | |
78 | int active; | |
79 | ||
c26655ca MS |
80 | /* Whether or not owning mapped_device is suspended */ |
81 | int suspended; | |
82 | ||
ccc45ea8 JB |
83 | mempool_t *pending_pool; |
84 | ||
85 | atomic_t pending_exceptions_count; | |
86 | ||
191437a5 JB |
87 | struct dm_exception_table pending; |
88 | struct dm_exception_table complete; | |
ccc45ea8 JB |
89 | |
90 | /* | |
91 | * pe_lock protects all pending_exception operations and access | |
92 | * as well as the snapshot_bios list. | |
93 | */ | |
94 | spinlock_t pe_lock; | |
95 | ||
96 | /* The on disk metadata handler */ | |
97 | struct dm_exception_store *store; | |
98 | ||
99 | struct dm_kcopyd_client *kcopyd_client; | |
100 | ||
101 | /* Queue of snapshot writes for ksnapd to flush */ | |
102 | struct bio_list queued_bios; | |
103 | struct work_struct queued_bios_work; | |
104 | ||
105 | /* Chunks with outstanding reads */ | |
106 | mempool_t *tracked_chunk_pool; | |
107 | spinlock_t tracked_chunk_lock; | |
108 | struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE]; | |
109 | }; | |
110 | ||
fc56f6fb MS |
111 | struct dm_dev *dm_snap_cow(struct dm_snapshot *s) |
112 | { | |
113 | return s->cow; | |
114 | } | |
115 | EXPORT_SYMBOL(dm_snap_cow); | |
116 | ||
c642f9e0 | 117 | static struct workqueue_struct *ksnapd; |
c4028958 | 118 | static void flush_queued_bios(struct work_struct *work); |
ca3a931f | 119 | |
ccc45ea8 JB |
120 | static sector_t chunk_to_sector(struct dm_exception_store *store, |
121 | chunk_t chunk) | |
122 | { | |
123 | return chunk << store->chunk_shift; | |
124 | } | |
125 | ||
126 | static int bdev_equal(struct block_device *lhs, struct block_device *rhs) | |
127 | { | |
128 | /* | |
129 | * There is only ever one instance of a particular block | |
130 | * device so we can compare pointers safely. | |
131 | */ | |
132 | return lhs == rhs; | |
133 | } | |
134 | ||
028867ac | 135 | struct dm_snap_pending_exception { |
1d4989c8 | 136 | struct dm_exception e; |
1da177e4 LT |
137 | |
138 | /* | |
139 | * Origin buffers waiting for this to complete are held | |
140 | * in a bio list | |
141 | */ | |
142 | struct bio_list origin_bios; | |
143 | struct bio_list snapshot_bios; | |
144 | ||
1da177e4 LT |
145 | /* Pointer back to snapshot context */ |
146 | struct dm_snapshot *snap; | |
147 | ||
148 | /* | |
149 | * 1 indicates the exception has already been sent to | |
150 | * kcopyd. | |
151 | */ | |
152 | int started; | |
153 | }; | |
154 | ||
155 | /* | |
156 | * Hash table mapping origin volumes to lists of snapshots and | |
157 | * a lock to protect it | |
158 | */ | |
e18b890b CL |
159 | static struct kmem_cache *exception_cache; |
160 | static struct kmem_cache *pending_cache; | |
1da177e4 | 161 | |
cd45daff MP |
162 | struct dm_snap_tracked_chunk { |
163 | struct hlist_node node; | |
164 | chunk_t chunk; | |
165 | }; | |
166 | ||
167 | static struct kmem_cache *tracked_chunk_cache; | |
168 | ||
169 | static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s, | |
170 | chunk_t chunk) | |
171 | { | |
172 | struct dm_snap_tracked_chunk *c = mempool_alloc(s->tracked_chunk_pool, | |
173 | GFP_NOIO); | |
174 | unsigned long flags; | |
175 | ||
176 | c->chunk = chunk; | |
177 | ||
178 | spin_lock_irqsave(&s->tracked_chunk_lock, flags); | |
179 | hlist_add_head(&c->node, | |
180 | &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]); | |
181 | spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); | |
182 | ||
183 | return c; | |
184 | } | |
185 | ||
186 | static void stop_tracking_chunk(struct dm_snapshot *s, | |
187 | struct dm_snap_tracked_chunk *c) | |
188 | { | |
189 | unsigned long flags; | |
190 | ||
191 | spin_lock_irqsave(&s->tracked_chunk_lock, flags); | |
192 | hlist_del(&c->node); | |
193 | spin_unlock_irqrestore(&s->tracked_chunk_lock, flags); | |
194 | ||
195 | mempool_free(c, s->tracked_chunk_pool); | |
196 | } | |
197 | ||
a8d41b59 MP |
198 | static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk) |
199 | { | |
200 | struct dm_snap_tracked_chunk *c; | |
201 | struct hlist_node *hn; | |
202 | int found = 0; | |
203 | ||
204 | spin_lock_irq(&s->tracked_chunk_lock); | |
205 | ||
206 | hlist_for_each_entry(c, hn, | |
207 | &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) { | |
208 | if (c->chunk == chunk) { | |
209 | found = 1; | |
210 | break; | |
211 | } | |
212 | } | |
213 | ||
214 | spin_unlock_irq(&s->tracked_chunk_lock); | |
215 | ||
216 | return found; | |
217 | } | |
218 | ||
615d1eb9 MS |
219 | /* |
220 | * This conflicting I/O is extremely improbable in the caller, | |
221 | * so msleep(1) is sufficient and there is no need for a wait queue. | |
222 | */ | |
223 | static void __check_for_conflicting_io(struct dm_snapshot *s, chunk_t chunk) | |
224 | { | |
225 | while (__chunk_is_tracked(s, chunk)) | |
226 | msleep(1); | |
227 | } | |
228 | ||
1da177e4 LT |
229 | /* |
230 | * One of these per registered origin, held in the snapshot_origins hash | |
231 | */ | |
232 | struct origin { | |
233 | /* The origin device */ | |
234 | struct block_device *bdev; | |
235 | ||
236 | struct list_head hash_list; | |
237 | ||
238 | /* List of snapshots for this origin */ | |
239 | struct list_head snapshots; | |
240 | }; | |
241 | ||
242 | /* | |
243 | * Size of the hash table for origin volumes. If we make this | |
244 | * the size of the minors list then it should be nearly perfect | |
245 | */ | |
246 | #define ORIGIN_HASH_SIZE 256 | |
247 | #define ORIGIN_MASK 0xFF | |
248 | static struct list_head *_origins; | |
249 | static struct rw_semaphore _origins_lock; | |
250 | ||
251 | static int init_origin_hash(void) | |
252 | { | |
253 | int i; | |
254 | ||
255 | _origins = kmalloc(ORIGIN_HASH_SIZE * sizeof(struct list_head), | |
256 | GFP_KERNEL); | |
257 | if (!_origins) { | |
72d94861 | 258 | DMERR("unable to allocate memory"); |
1da177e4 LT |
259 | return -ENOMEM; |
260 | } | |
261 | ||
262 | for (i = 0; i < ORIGIN_HASH_SIZE; i++) | |
263 | INIT_LIST_HEAD(_origins + i); | |
264 | init_rwsem(&_origins_lock); | |
265 | ||
266 | return 0; | |
267 | } | |
268 | ||
269 | static void exit_origin_hash(void) | |
270 | { | |
271 | kfree(_origins); | |
272 | } | |
273 | ||
028867ac | 274 | static unsigned origin_hash(struct block_device *bdev) |
1da177e4 LT |
275 | { |
276 | return bdev->bd_dev & ORIGIN_MASK; | |
277 | } | |
278 | ||
279 | static struct origin *__lookup_origin(struct block_device *origin) | |
280 | { | |
281 | struct list_head *ol; | |
282 | struct origin *o; | |
283 | ||
284 | ol = &_origins[origin_hash(origin)]; | |
285 | list_for_each_entry (o, ol, hash_list) | |
286 | if (bdev_equal(o->bdev, origin)) | |
287 | return o; | |
288 | ||
289 | return NULL; | |
290 | } | |
291 | ||
292 | static void __insert_origin(struct origin *o) | |
293 | { | |
294 | struct list_head *sl = &_origins[origin_hash(o->bdev)]; | |
295 | list_add_tail(&o->hash_list, sl); | |
296 | } | |
297 | ||
c1f0c183 MS |
298 | /* |
299 | * _origins_lock must be held when calling this function. | |
300 | * Returns number of snapshots registered using the supplied cow device, plus: | |
301 | * snap_src - a snapshot suitable for use as a source of exception handover | |
302 | * snap_dest - a snapshot capable of receiving exception handover. | |
9d3b15c4 MP |
303 | * snap_merge - an existing snapshot-merge target linked to the same origin. |
304 | * There can be at most one snapshot-merge target. The parameter is optional. | |
c1f0c183 | 305 | * |
9d3b15c4 | 306 | * Possible return values and states of snap_src and snap_dest. |
c1f0c183 MS |
307 | * 0: NULL, NULL - first new snapshot |
308 | * 1: snap_src, NULL - normal snapshot | |
309 | * 2: snap_src, snap_dest - waiting for handover | |
310 | * 2: snap_src, NULL - handed over, waiting for old to be deleted | |
311 | * 1: NULL, snap_dest - source got destroyed without handover | |
312 | */ | |
313 | static int __find_snapshots_sharing_cow(struct dm_snapshot *snap, | |
314 | struct dm_snapshot **snap_src, | |
9d3b15c4 MP |
315 | struct dm_snapshot **snap_dest, |
316 | struct dm_snapshot **snap_merge) | |
c1f0c183 MS |
317 | { |
318 | struct dm_snapshot *s; | |
319 | struct origin *o; | |
320 | int count = 0; | |
321 | int active; | |
322 | ||
323 | o = __lookup_origin(snap->origin->bdev); | |
324 | if (!o) | |
325 | goto out; | |
326 | ||
327 | list_for_each_entry(s, &o->snapshots, list) { | |
9d3b15c4 MP |
328 | if (dm_target_is_snapshot_merge(s->ti) && snap_merge) |
329 | *snap_merge = s; | |
c1f0c183 MS |
330 | if (!bdev_equal(s->cow->bdev, snap->cow->bdev)) |
331 | continue; | |
332 | ||
333 | down_read(&s->lock); | |
334 | active = s->active; | |
335 | up_read(&s->lock); | |
336 | ||
337 | if (active) { | |
338 | if (snap_src) | |
339 | *snap_src = s; | |
340 | } else if (snap_dest) | |
341 | *snap_dest = s; | |
342 | ||
343 | count++; | |
344 | } | |
345 | ||
346 | out: | |
347 | return count; | |
348 | } | |
349 | ||
350 | /* | |
351 | * On success, returns 1 if this snapshot is a handover destination, | |
352 | * otherwise returns 0. | |
353 | */ | |
354 | static int __validate_exception_handover(struct dm_snapshot *snap) | |
355 | { | |
356 | struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; | |
9d3b15c4 | 357 | struct dm_snapshot *snap_merge = NULL; |
c1f0c183 MS |
358 | |
359 | /* Does snapshot need exceptions handed over to it? */ | |
9d3b15c4 MP |
360 | if ((__find_snapshots_sharing_cow(snap, &snap_src, &snap_dest, |
361 | &snap_merge) == 2) || | |
c1f0c183 MS |
362 | snap_dest) { |
363 | snap->ti->error = "Snapshot cow pairing for exception " | |
364 | "table handover failed"; | |
365 | return -EINVAL; | |
366 | } | |
367 | ||
368 | /* | |
369 | * If no snap_src was found, snap cannot become a handover | |
370 | * destination. | |
371 | */ | |
372 | if (!snap_src) | |
373 | return 0; | |
374 | ||
9d3b15c4 MP |
375 | /* |
376 | * Non-snapshot-merge handover? | |
377 | */ | |
378 | if (!dm_target_is_snapshot_merge(snap->ti)) | |
379 | return 1; | |
380 | ||
381 | /* | |
382 | * Do not allow more than one merging snapshot. | |
383 | */ | |
384 | if (snap_merge) { | |
385 | snap->ti->error = "A snapshot is already merging."; | |
386 | return -EINVAL; | |
387 | } | |
388 | ||
c1f0c183 MS |
389 | return 1; |
390 | } | |
391 | ||
392 | static void __insert_snapshot(struct origin *o, struct dm_snapshot *s) | |
393 | { | |
394 | struct dm_snapshot *l; | |
395 | ||
396 | /* Sort the list according to chunk size, largest-first smallest-last */ | |
397 | list_for_each_entry(l, &o->snapshots, list) | |
398 | if (l->store->chunk_size < s->store->chunk_size) | |
399 | break; | |
400 | list_add_tail(&s->list, &l->list); | |
401 | } | |
402 | ||
1da177e4 LT |
403 | /* |
404 | * Make a note of the snapshot and its origin so we can look it | |
405 | * up when the origin has a write on it. | |
c1f0c183 MS |
406 | * |
407 | * Also validate snapshot exception store handovers. | |
408 | * On success, returns 1 if this registration is a handover destination, | |
409 | * otherwise returns 0. | |
1da177e4 LT |
410 | */ |
411 | static int register_snapshot(struct dm_snapshot *snap) | |
412 | { | |
c1f0c183 | 413 | struct origin *o, *new_o = NULL; |
1da177e4 | 414 | struct block_device *bdev = snap->origin->bdev; |
c1f0c183 | 415 | int r = 0; |
1da177e4 | 416 | |
60c856c8 MP |
417 | new_o = kmalloc(sizeof(*new_o), GFP_KERNEL); |
418 | if (!new_o) | |
419 | return -ENOMEM; | |
420 | ||
1da177e4 | 421 | down_write(&_origins_lock); |
1da177e4 | 422 | |
c1f0c183 MS |
423 | r = __validate_exception_handover(snap); |
424 | if (r < 0) { | |
425 | kfree(new_o); | |
426 | goto out; | |
427 | } | |
428 | ||
429 | o = __lookup_origin(bdev); | |
60c856c8 MP |
430 | if (o) |
431 | kfree(new_o); | |
432 | else { | |
1da177e4 | 433 | /* New origin */ |
60c856c8 | 434 | o = new_o; |
1da177e4 LT |
435 | |
436 | /* Initialise the struct */ | |
437 | INIT_LIST_HEAD(&o->snapshots); | |
438 | o->bdev = bdev; | |
439 | ||
440 | __insert_origin(o); | |
441 | } | |
442 | ||
c1f0c183 MS |
443 | __insert_snapshot(o, snap); |
444 | ||
445 | out: | |
446 | up_write(&_origins_lock); | |
447 | ||
448 | return r; | |
449 | } | |
450 | ||
451 | /* | |
452 | * Move snapshot to correct place in list according to chunk size. | |
453 | */ | |
454 | static void reregister_snapshot(struct dm_snapshot *s) | |
455 | { | |
456 | struct block_device *bdev = s->origin->bdev; | |
457 | ||
458 | down_write(&_origins_lock); | |
459 | ||
460 | list_del(&s->list); | |
461 | __insert_snapshot(__lookup_origin(bdev), s); | |
1da177e4 LT |
462 | |
463 | up_write(&_origins_lock); | |
1da177e4 LT |
464 | } |
465 | ||
466 | static void unregister_snapshot(struct dm_snapshot *s) | |
467 | { | |
468 | struct origin *o; | |
469 | ||
470 | down_write(&_origins_lock); | |
471 | o = __lookup_origin(s->origin->bdev); | |
472 | ||
473 | list_del(&s->list); | |
c1f0c183 | 474 | if (o && list_empty(&o->snapshots)) { |
1da177e4 LT |
475 | list_del(&o->hash_list); |
476 | kfree(o); | |
477 | } | |
478 | ||
479 | up_write(&_origins_lock); | |
480 | } | |
481 | ||
482 | /* | |
483 | * Implementation of the exception hash tables. | |
d74f81f8 MB |
484 | * The lowest hash_shift bits of the chunk number are ignored, allowing |
485 | * some consecutive chunks to be grouped together. | |
1da177e4 | 486 | */ |
3510cb94 JB |
487 | static int dm_exception_table_init(struct dm_exception_table *et, |
488 | uint32_t size, unsigned hash_shift) | |
1da177e4 LT |
489 | { |
490 | unsigned int i; | |
491 | ||
d74f81f8 | 492 | et->hash_shift = hash_shift; |
1da177e4 LT |
493 | et->hash_mask = size - 1; |
494 | et->table = dm_vcalloc(size, sizeof(struct list_head)); | |
495 | if (!et->table) | |
496 | return -ENOMEM; | |
497 | ||
498 | for (i = 0; i < size; i++) | |
499 | INIT_LIST_HEAD(et->table + i); | |
500 | ||
501 | return 0; | |
502 | } | |
503 | ||
3510cb94 JB |
504 | static void dm_exception_table_exit(struct dm_exception_table *et, |
505 | struct kmem_cache *mem) | |
1da177e4 LT |
506 | { |
507 | struct list_head *slot; | |
1d4989c8 | 508 | struct dm_exception *ex, *next; |
1da177e4 LT |
509 | int i, size; |
510 | ||
511 | size = et->hash_mask + 1; | |
512 | for (i = 0; i < size; i++) { | |
513 | slot = et->table + i; | |
514 | ||
515 | list_for_each_entry_safe (ex, next, slot, hash_list) | |
516 | kmem_cache_free(mem, ex); | |
517 | } | |
518 | ||
519 | vfree(et->table); | |
520 | } | |
521 | ||
191437a5 | 522 | static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk) |
1da177e4 | 523 | { |
d74f81f8 | 524 | return (chunk >> et->hash_shift) & et->hash_mask; |
1da177e4 LT |
525 | } |
526 | ||
3510cb94 | 527 | static void dm_remove_exception(struct dm_exception *e) |
1da177e4 LT |
528 | { |
529 | list_del(&e->hash_list); | |
530 | } | |
531 | ||
532 | /* | |
533 | * Return the exception data for a sector, or NULL if not | |
534 | * remapped. | |
535 | */ | |
3510cb94 JB |
536 | static struct dm_exception *dm_lookup_exception(struct dm_exception_table *et, |
537 | chunk_t chunk) | |
1da177e4 LT |
538 | { |
539 | struct list_head *slot; | |
1d4989c8 | 540 | struct dm_exception *e; |
1da177e4 LT |
541 | |
542 | slot = &et->table[exception_hash(et, chunk)]; | |
543 | list_for_each_entry (e, slot, hash_list) | |
d74f81f8 MB |
544 | if (chunk >= e->old_chunk && |
545 | chunk <= e->old_chunk + dm_consecutive_chunk_count(e)) | |
1da177e4 LT |
546 | return e; |
547 | ||
548 | return NULL; | |
549 | } | |
550 | ||
3510cb94 | 551 | static struct dm_exception *alloc_completed_exception(void) |
1da177e4 | 552 | { |
1d4989c8 | 553 | struct dm_exception *e; |
1da177e4 LT |
554 | |
555 | e = kmem_cache_alloc(exception_cache, GFP_NOIO); | |
556 | if (!e) | |
557 | e = kmem_cache_alloc(exception_cache, GFP_ATOMIC); | |
558 | ||
559 | return e; | |
560 | } | |
561 | ||
3510cb94 | 562 | static void free_completed_exception(struct dm_exception *e) |
1da177e4 LT |
563 | { |
564 | kmem_cache_free(exception_cache, e); | |
565 | } | |
566 | ||
92e86812 | 567 | static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s) |
1da177e4 | 568 | { |
92e86812 MP |
569 | struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool, |
570 | GFP_NOIO); | |
571 | ||
879129d2 | 572 | atomic_inc(&s->pending_exceptions_count); |
92e86812 MP |
573 | pe->snap = s; |
574 | ||
575 | return pe; | |
1da177e4 LT |
576 | } |
577 | ||
028867ac | 578 | static void free_pending_exception(struct dm_snap_pending_exception *pe) |
1da177e4 | 579 | { |
879129d2 MP |
580 | struct dm_snapshot *s = pe->snap; |
581 | ||
582 | mempool_free(pe, s->pending_pool); | |
583 | smp_mb__before_atomic_dec(); | |
584 | atomic_dec(&s->pending_exceptions_count); | |
1da177e4 LT |
585 | } |
586 | ||
3510cb94 JB |
587 | static void dm_insert_exception(struct dm_exception_table *eh, |
588 | struct dm_exception *new_e) | |
d74f81f8 | 589 | { |
d74f81f8 | 590 | struct list_head *l; |
1d4989c8 | 591 | struct dm_exception *e = NULL; |
d74f81f8 MB |
592 | |
593 | l = &eh->table[exception_hash(eh, new_e->old_chunk)]; | |
594 | ||
595 | /* Add immediately if this table doesn't support consecutive chunks */ | |
596 | if (!eh->hash_shift) | |
597 | goto out; | |
598 | ||
599 | /* List is ordered by old_chunk */ | |
600 | list_for_each_entry_reverse(e, l, hash_list) { | |
601 | /* Insert after an existing chunk? */ | |
602 | if (new_e->old_chunk == (e->old_chunk + | |
603 | dm_consecutive_chunk_count(e) + 1) && | |
604 | new_e->new_chunk == (dm_chunk_number(e->new_chunk) + | |
605 | dm_consecutive_chunk_count(e) + 1)) { | |
606 | dm_consecutive_chunk_count_inc(e); | |
3510cb94 | 607 | free_completed_exception(new_e); |
d74f81f8 MB |
608 | return; |
609 | } | |
610 | ||
611 | /* Insert before an existing chunk? */ | |
612 | if (new_e->old_chunk == (e->old_chunk - 1) && | |
613 | new_e->new_chunk == (dm_chunk_number(e->new_chunk) - 1)) { | |
614 | dm_consecutive_chunk_count_inc(e); | |
615 | e->old_chunk--; | |
616 | e->new_chunk--; | |
3510cb94 | 617 | free_completed_exception(new_e); |
d74f81f8 MB |
618 | return; |
619 | } | |
620 | ||
621 | if (new_e->old_chunk > e->old_chunk) | |
622 | break; | |
623 | } | |
624 | ||
625 | out: | |
626 | list_add(&new_e->hash_list, e ? &e->hash_list : l); | |
627 | } | |
628 | ||
a159c1ac JB |
629 | /* |
630 | * Callback used by the exception stores to load exceptions when | |
631 | * initialising. | |
632 | */ | |
633 | static int dm_add_exception(void *context, chunk_t old, chunk_t new) | |
1da177e4 | 634 | { |
a159c1ac | 635 | struct dm_snapshot *s = context; |
1d4989c8 | 636 | struct dm_exception *e; |
1da177e4 | 637 | |
3510cb94 | 638 | e = alloc_completed_exception(); |
1da177e4 LT |
639 | if (!e) |
640 | return -ENOMEM; | |
641 | ||
642 | e->old_chunk = old; | |
d74f81f8 MB |
643 | |
644 | /* Consecutive_count is implicitly initialised to zero */ | |
1da177e4 | 645 | e->new_chunk = new; |
d74f81f8 | 646 | |
3510cb94 | 647 | dm_insert_exception(&s->complete, e); |
d74f81f8 | 648 | |
1da177e4 LT |
649 | return 0; |
650 | } | |
651 | ||
7e201b35 MP |
652 | #define min_not_zero(l, r) (((l) == 0) ? (r) : (((r) == 0) ? (l) : min(l, r))) |
653 | ||
654 | /* | |
655 | * Return a minimum chunk size of all snapshots that have the specified origin. | |
656 | * Return zero if the origin has no snapshots. | |
657 | */ | |
658 | static sector_t __minimum_chunk_size(struct origin *o) | |
659 | { | |
660 | struct dm_snapshot *snap; | |
661 | unsigned chunk_size = 0; | |
662 | ||
663 | if (o) | |
664 | list_for_each_entry(snap, &o->snapshots, list) | |
665 | chunk_size = min_not_zero(chunk_size, | |
666 | snap->store->chunk_size); | |
667 | ||
668 | return chunk_size; | |
669 | } | |
670 | ||
1da177e4 LT |
671 | /* |
672 | * Hard coded magic. | |
673 | */ | |
674 | static int calc_max_buckets(void) | |
675 | { | |
676 | /* use a fixed size of 2MB */ | |
677 | unsigned long mem = 2 * 1024 * 1024; | |
678 | mem /= sizeof(struct list_head); | |
679 | ||
680 | return mem; | |
681 | } | |
682 | ||
1da177e4 LT |
683 | /* |
684 | * Allocate room for a suitable hash table. | |
685 | */ | |
fee1998e | 686 | static int init_hash_tables(struct dm_snapshot *s) |
1da177e4 LT |
687 | { |
688 | sector_t hash_size, cow_dev_size, origin_dev_size, max_buckets; | |
689 | ||
690 | /* | |
691 | * Calculate based on the size of the original volume or | |
692 | * the COW volume... | |
693 | */ | |
fc56f6fb | 694 | cow_dev_size = get_dev_size(s->cow->bdev); |
1da177e4 LT |
695 | origin_dev_size = get_dev_size(s->origin->bdev); |
696 | max_buckets = calc_max_buckets(); | |
697 | ||
fee1998e | 698 | hash_size = min(origin_dev_size, cow_dev_size) >> s->store->chunk_shift; |
1da177e4 LT |
699 | hash_size = min(hash_size, max_buckets); |
700 | ||
8e87b9b8 MP |
701 | if (hash_size < 64) |
702 | hash_size = 64; | |
8defd830 | 703 | hash_size = rounddown_pow_of_two(hash_size); |
3510cb94 JB |
704 | if (dm_exception_table_init(&s->complete, hash_size, |
705 | DM_CHUNK_CONSECUTIVE_BITS)) | |
1da177e4 LT |
706 | return -ENOMEM; |
707 | ||
708 | /* | |
709 | * Allocate hash table for in-flight exceptions | |
710 | * Make this smaller than the real hash table | |
711 | */ | |
712 | hash_size >>= 3; | |
713 | if (hash_size < 64) | |
714 | hash_size = 64; | |
715 | ||
3510cb94 JB |
716 | if (dm_exception_table_init(&s->pending, hash_size, 0)) { |
717 | dm_exception_table_exit(&s->complete, exception_cache); | |
1da177e4 LT |
718 | return -ENOMEM; |
719 | } | |
720 | ||
721 | return 0; | |
722 | } | |
723 | ||
1da177e4 LT |
724 | /* |
725 | * Construct a snapshot mapping: <origin_dev> <COW-dev> <p/n> <chunk-size> | |
726 | */ | |
727 | static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) | |
728 | { | |
729 | struct dm_snapshot *s; | |
cd45daff | 730 | int i; |
1da177e4 | 731 | int r = -EINVAL; |
fc56f6fb | 732 | char *origin_path, *cow_path; |
10b8106a MS |
733 | unsigned args_used, num_flush_requests = 1; |
734 | fmode_t origin_mode = FMODE_READ; | |
1da177e4 | 735 | |
4c7e3bf4 | 736 | if (argc != 4) { |
72d94861 | 737 | ti->error = "requires exactly 4 arguments"; |
1da177e4 | 738 | r = -EINVAL; |
fc56f6fb | 739 | goto bad; |
1da177e4 LT |
740 | } |
741 | ||
10b8106a MS |
742 | if (dm_target_is_snapshot_merge(ti)) { |
743 | num_flush_requests = 2; | |
744 | origin_mode = FMODE_WRITE; | |
745 | } | |
746 | ||
1da177e4 | 747 | origin_path = argv[0]; |
fee1998e JB |
748 | argv++; |
749 | argc--; | |
1da177e4 | 750 | |
fc56f6fb MS |
751 | s = kmalloc(sizeof(*s), GFP_KERNEL); |
752 | if (!s) { | |
753 | ti->error = "Cannot allocate snapshot context private " | |
754 | "structure"; | |
755 | r = -ENOMEM; | |
756 | goto bad; | |
757 | } | |
758 | ||
759 | cow_path = argv[0]; | |
760 | argv++; | |
761 | argc--; | |
762 | ||
763 | r = dm_get_device(ti, cow_path, 0, 0, | |
764 | FMODE_READ | FMODE_WRITE, &s->cow); | |
765 | if (r) { | |
766 | ti->error = "Cannot get COW device"; | |
767 | goto bad_cow; | |
768 | } | |
769 | ||
770 | r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store); | |
fee1998e JB |
771 | if (r) { |
772 | ti->error = "Couldn't create exception store"; | |
1da177e4 | 773 | r = -EINVAL; |
fc56f6fb | 774 | goto bad_store; |
1da177e4 LT |
775 | } |
776 | ||
fee1998e JB |
777 | argv += args_used; |
778 | argc -= args_used; | |
779 | ||
10b8106a | 780 | r = dm_get_device(ti, origin_path, 0, ti->len, origin_mode, &s->origin); |
1da177e4 LT |
781 | if (r) { |
782 | ti->error = "Cannot get origin device"; | |
fee1998e | 783 | goto bad_origin; |
1da177e4 LT |
784 | } |
785 | ||
fc56f6fb | 786 | s->ti = ti; |
1da177e4 | 787 | s->valid = 1; |
aa14edeb | 788 | s->active = 0; |
c26655ca | 789 | s->suspended = 0; |
879129d2 | 790 | atomic_set(&s->pending_exceptions_count, 0); |
1da177e4 | 791 | init_rwsem(&s->lock); |
c1f0c183 | 792 | INIT_LIST_HEAD(&s->list); |
ca3a931f | 793 | spin_lock_init(&s->pe_lock); |
1da177e4 LT |
794 | |
795 | /* Allocate hash table for COW data */ | |
fee1998e | 796 | if (init_hash_tables(s)) { |
1da177e4 LT |
797 | ti->error = "Unable to allocate hash table space"; |
798 | r = -ENOMEM; | |
fee1998e | 799 | goto bad_hash_tables; |
1da177e4 LT |
800 | } |
801 | ||
eb69aca5 | 802 | r = dm_kcopyd_client_create(SNAPSHOT_PAGES, &s->kcopyd_client); |
1da177e4 LT |
803 | if (r) { |
804 | ti->error = "Could not create kcopyd client"; | |
fee1998e | 805 | goto bad_kcopyd; |
1da177e4 LT |
806 | } |
807 | ||
92e86812 MP |
808 | s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache); |
809 | if (!s->pending_pool) { | |
810 | ti->error = "Could not allocate mempool for pending exceptions"; | |
fee1998e | 811 | goto bad_pending_pool; |
92e86812 MP |
812 | } |
813 | ||
cd45daff MP |
814 | s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS, |
815 | tracked_chunk_cache); | |
816 | if (!s->tracked_chunk_pool) { | |
817 | ti->error = "Could not allocate tracked_chunk mempool for " | |
818 | "tracking reads"; | |
92e86812 | 819 | goto bad_tracked_chunk_pool; |
cd45daff MP |
820 | } |
821 | ||
822 | for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) | |
823 | INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]); | |
824 | ||
825 | spin_lock_init(&s->tracked_chunk_lock); | |
826 | ||
c1f0c183 MS |
827 | bio_list_init(&s->queued_bios); |
828 | INIT_WORK(&s->queued_bios_work, flush_queued_bios); | |
829 | ||
830 | ti->private = s; | |
10b8106a | 831 | ti->num_flush_requests = num_flush_requests; |
c1f0c183 MS |
832 | |
833 | /* Add snapshot to the list of snapshots for this origin */ | |
834 | /* Exceptions aren't triggered till snapshot_resume() is called */ | |
835 | r = register_snapshot(s); | |
836 | if (r == -ENOMEM) { | |
837 | ti->error = "Snapshot origin struct allocation failed"; | |
838 | goto bad_load_and_register; | |
839 | } else if (r < 0) { | |
840 | /* invalid handover, register_snapshot has set ti->error */ | |
841 | goto bad_load_and_register; | |
842 | } | |
843 | ||
844 | /* | |
845 | * Metadata must only be loaded into one table at once, so skip this | |
846 | * if metadata will be handed over during resume. | |
847 | * Chunk size will be set during the handover - set it to zero to | |
848 | * ensure it's ignored. | |
849 | */ | |
850 | if (r > 0) { | |
851 | s->store->chunk_size = 0; | |
852 | return 0; | |
853 | } | |
854 | ||
493df71c JB |
855 | r = s->store->type->read_metadata(s->store, dm_add_exception, |
856 | (void *)s); | |
0764147b | 857 | if (r < 0) { |
f9cea4f7 | 858 | ti->error = "Failed to read snapshot metadata"; |
c1f0c183 | 859 | goto bad_read_metadata; |
0764147b MB |
860 | } else if (r > 0) { |
861 | s->valid = 0; | |
862 | DMWARN("Snapshot is marked invalid."); | |
f9cea4f7 | 863 | } |
aa14edeb | 864 | |
3f2412dc MP |
865 | if (!s->store->chunk_size) { |
866 | ti->error = "Chunk size not set"; | |
c1f0c183 | 867 | goto bad_read_metadata; |
1da177e4 | 868 | } |
d0216849 | 869 | ti->split_io = s->store->chunk_size; |
1da177e4 LT |
870 | |
871 | return 0; | |
872 | ||
c1f0c183 MS |
873 | bad_read_metadata: |
874 | unregister_snapshot(s); | |
875 | ||
fee1998e | 876 | bad_load_and_register: |
cd45daff MP |
877 | mempool_destroy(s->tracked_chunk_pool); |
878 | ||
fee1998e | 879 | bad_tracked_chunk_pool: |
92e86812 MP |
880 | mempool_destroy(s->pending_pool); |
881 | ||
fee1998e | 882 | bad_pending_pool: |
eb69aca5 | 883 | dm_kcopyd_client_destroy(s->kcopyd_client); |
1da177e4 | 884 | |
fee1998e | 885 | bad_kcopyd: |
3510cb94 JB |
886 | dm_exception_table_exit(&s->pending, pending_cache); |
887 | dm_exception_table_exit(&s->complete, exception_cache); | |
1da177e4 | 888 | |
fee1998e | 889 | bad_hash_tables: |
1da177e4 LT |
890 | dm_put_device(ti, s->origin); |
891 | ||
fee1998e | 892 | bad_origin: |
fc56f6fb | 893 | dm_exception_store_destroy(s->store); |
1da177e4 | 894 | |
fc56f6fb MS |
895 | bad_store: |
896 | dm_put_device(ti, s->cow); | |
fee1998e | 897 | |
fc56f6fb MS |
898 | bad_cow: |
899 | kfree(s); | |
900 | ||
901 | bad: | |
1da177e4 LT |
902 | return r; |
903 | } | |
904 | ||
31c93a0c MB |
905 | static void __free_exceptions(struct dm_snapshot *s) |
906 | { | |
eb69aca5 | 907 | dm_kcopyd_client_destroy(s->kcopyd_client); |
31c93a0c MB |
908 | s->kcopyd_client = NULL; |
909 | ||
3510cb94 JB |
910 | dm_exception_table_exit(&s->pending, pending_cache); |
911 | dm_exception_table_exit(&s->complete, exception_cache); | |
31c93a0c MB |
912 | } |
913 | ||
c1f0c183 MS |
914 | static void __handover_exceptions(struct dm_snapshot *snap_src, |
915 | struct dm_snapshot *snap_dest) | |
916 | { | |
917 | union { | |
918 | struct dm_exception_table table_swap; | |
919 | struct dm_exception_store *store_swap; | |
920 | } u; | |
921 | ||
922 | /* | |
923 | * Swap all snapshot context information between the two instances. | |
924 | */ | |
925 | u.table_swap = snap_dest->complete; | |
926 | snap_dest->complete = snap_src->complete; | |
927 | snap_src->complete = u.table_swap; | |
928 | ||
929 | u.store_swap = snap_dest->store; | |
930 | snap_dest->store = snap_src->store; | |
931 | snap_src->store = u.store_swap; | |
932 | ||
933 | snap_dest->store->snap = snap_dest; | |
934 | snap_src->store->snap = snap_src; | |
935 | ||
936 | snap_dest->ti->split_io = snap_dest->store->chunk_size; | |
937 | snap_dest->valid = snap_src->valid; | |
938 | ||
939 | /* | |
940 | * Set source invalid to ensure it receives no further I/O. | |
941 | */ | |
942 | snap_src->valid = 0; | |
943 | } | |
944 | ||
1da177e4 LT |
945 | static void snapshot_dtr(struct dm_target *ti) |
946 | { | |
cd45daff MP |
947 | #ifdef CONFIG_DM_DEBUG |
948 | int i; | |
949 | #endif | |
028867ac | 950 | struct dm_snapshot *s = ti->private; |
c1f0c183 | 951 | struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; |
1da177e4 | 952 | |
ca3a931f AK |
953 | flush_workqueue(ksnapd); |
954 | ||
c1f0c183 MS |
955 | down_read(&_origins_lock); |
956 | /* Check whether exception handover must be cancelled */ | |
9d3b15c4 | 957 | (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); |
c1f0c183 MS |
958 | if (snap_src && snap_dest && (s == snap_src)) { |
959 | down_write(&snap_dest->lock); | |
960 | snap_dest->valid = 0; | |
961 | up_write(&snap_dest->lock); | |
962 | DMERR("Cancelling snapshot handover."); | |
963 | } | |
964 | up_read(&_origins_lock); | |
965 | ||
138728dc AK |
966 | /* Prevent further origin writes from using this snapshot. */ |
967 | /* After this returns there can be no new kcopyd jobs. */ | |
1da177e4 LT |
968 | unregister_snapshot(s); |
969 | ||
879129d2 | 970 | while (atomic_read(&s->pending_exceptions_count)) |
90fa1527 | 971 | msleep(1); |
879129d2 MP |
972 | /* |
973 | * Ensure instructions in mempool_destroy aren't reordered | |
974 | * before atomic_read. | |
975 | */ | |
976 | smp_mb(); | |
977 | ||
cd45daff MP |
978 | #ifdef CONFIG_DM_DEBUG |
979 | for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++) | |
980 | BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i])); | |
981 | #endif | |
982 | ||
983 | mempool_destroy(s->tracked_chunk_pool); | |
984 | ||
31c93a0c | 985 | __free_exceptions(s); |
1da177e4 | 986 | |
92e86812 MP |
987 | mempool_destroy(s->pending_pool); |
988 | ||
1da177e4 | 989 | dm_put_device(ti, s->origin); |
fee1998e JB |
990 | |
991 | dm_exception_store_destroy(s->store); | |
138728dc | 992 | |
fc56f6fb MS |
993 | dm_put_device(ti, s->cow); |
994 | ||
1da177e4 LT |
995 | kfree(s); |
996 | } | |
997 | ||
998 | /* | |
999 | * Flush a list of buffers. | |
1000 | */ | |
1001 | static void flush_bios(struct bio *bio) | |
1002 | { | |
1003 | struct bio *n; | |
1004 | ||
1005 | while (bio) { | |
1006 | n = bio->bi_next; | |
1007 | bio->bi_next = NULL; | |
1008 | generic_make_request(bio); | |
1009 | bio = n; | |
1010 | } | |
1011 | } | |
1012 | ||
c4028958 | 1013 | static void flush_queued_bios(struct work_struct *work) |
ca3a931f | 1014 | { |
c4028958 DH |
1015 | struct dm_snapshot *s = |
1016 | container_of(work, struct dm_snapshot, queued_bios_work); | |
ca3a931f AK |
1017 | struct bio *queued_bios; |
1018 | unsigned long flags; | |
1019 | ||
1020 | spin_lock_irqsave(&s->pe_lock, flags); | |
1021 | queued_bios = bio_list_get(&s->queued_bios); | |
1022 | spin_unlock_irqrestore(&s->pe_lock, flags); | |
1023 | ||
1024 | flush_bios(queued_bios); | |
1025 | } | |
1026 | ||
515ad66c MP |
1027 | static int do_origin(struct dm_dev *origin, struct bio *bio); |
1028 | ||
1029 | /* | |
1030 | * Flush a list of buffers. | |
1031 | */ | |
1032 | static void retry_origin_bios(struct dm_snapshot *s, struct bio *bio) | |
1033 | { | |
1034 | struct bio *n; | |
1035 | int r; | |
1036 | ||
1037 | while (bio) { | |
1038 | n = bio->bi_next; | |
1039 | bio->bi_next = NULL; | |
1040 | r = do_origin(s->origin, bio); | |
1041 | if (r == DM_MAPIO_REMAPPED) | |
1042 | generic_make_request(bio); | |
1043 | bio = n; | |
1044 | } | |
1045 | } | |
1046 | ||
1da177e4 LT |
1047 | /* |
1048 | * Error a list of buffers. | |
1049 | */ | |
1050 | static void error_bios(struct bio *bio) | |
1051 | { | |
1052 | struct bio *n; | |
1053 | ||
1054 | while (bio) { | |
1055 | n = bio->bi_next; | |
1056 | bio->bi_next = NULL; | |
6712ecf8 | 1057 | bio_io_error(bio); |
1da177e4 LT |
1058 | bio = n; |
1059 | } | |
1060 | } | |
1061 | ||
695368ac | 1062 | static void __invalidate_snapshot(struct dm_snapshot *s, int err) |
76df1c65 AK |
1063 | { |
1064 | if (!s->valid) | |
1065 | return; | |
1066 | ||
1067 | if (err == -EIO) | |
1068 | DMERR("Invalidating snapshot: Error reading/writing."); | |
1069 | else if (err == -ENOMEM) | |
1070 | DMERR("Invalidating snapshot: Unable to allocate exception."); | |
1071 | ||
493df71c JB |
1072 | if (s->store->type->drop_snapshot) |
1073 | s->store->type->drop_snapshot(s->store); | |
76df1c65 AK |
1074 | |
1075 | s->valid = 0; | |
1076 | ||
fc56f6fb | 1077 | dm_table_event(s->ti->table); |
76df1c65 AK |
1078 | } |
1079 | ||
028867ac | 1080 | static void pending_complete(struct dm_snap_pending_exception *pe, int success) |
1da177e4 | 1081 | { |
1d4989c8 | 1082 | struct dm_exception *e; |
1da177e4 | 1083 | struct dm_snapshot *s = pe->snap; |
9d493fa8 AK |
1084 | struct bio *origin_bios = NULL; |
1085 | struct bio *snapshot_bios = NULL; | |
1086 | int error = 0; | |
1da177e4 | 1087 | |
76df1c65 AK |
1088 | if (!success) { |
1089 | /* Read/write error - snapshot is unusable */ | |
1da177e4 | 1090 | down_write(&s->lock); |
695368ac | 1091 | __invalidate_snapshot(s, -EIO); |
9d493fa8 | 1092 | error = 1; |
76df1c65 AK |
1093 | goto out; |
1094 | } | |
1095 | ||
3510cb94 | 1096 | e = alloc_completed_exception(); |
76df1c65 | 1097 | if (!e) { |
1da177e4 | 1098 | down_write(&s->lock); |
695368ac | 1099 | __invalidate_snapshot(s, -ENOMEM); |
9d493fa8 | 1100 | error = 1; |
76df1c65 AK |
1101 | goto out; |
1102 | } | |
1103 | *e = pe->e; | |
1da177e4 | 1104 | |
76df1c65 AK |
1105 | down_write(&s->lock); |
1106 | if (!s->valid) { | |
3510cb94 | 1107 | free_completed_exception(e); |
9d493fa8 | 1108 | error = 1; |
76df1c65 | 1109 | goto out; |
1da177e4 LT |
1110 | } |
1111 | ||
615d1eb9 MS |
1112 | /* Check for conflicting reads */ |
1113 | __check_for_conflicting_io(s, pe->e.old_chunk); | |
a8d41b59 | 1114 | |
9d493fa8 AK |
1115 | /* |
1116 | * Add a proper exception, and remove the | |
1117 | * in-flight exception from the list. | |
1118 | */ | |
3510cb94 | 1119 | dm_insert_exception(&s->complete, e); |
76df1c65 | 1120 | |
1da177e4 | 1121 | out: |
3510cb94 | 1122 | dm_remove_exception(&pe->e); |
9d493fa8 | 1123 | snapshot_bios = bio_list_get(&pe->snapshot_bios); |
515ad66c MP |
1124 | origin_bios = bio_list_get(&pe->origin_bios); |
1125 | free_pending_exception(pe); | |
1da177e4 | 1126 | |
9d493fa8 AK |
1127 | up_write(&s->lock); |
1128 | ||
1129 | /* Submit any pending write bios */ | |
1130 | if (error) | |
1131 | error_bios(snapshot_bios); | |
1132 | else | |
1133 | flush_bios(snapshot_bios); | |
1134 | ||
515ad66c | 1135 | retry_origin_bios(s, origin_bios); |
1da177e4 LT |
1136 | } |
1137 | ||
1138 | static void commit_callback(void *context, int success) | |
1139 | { | |
028867ac AK |
1140 | struct dm_snap_pending_exception *pe = context; |
1141 | ||
1da177e4 LT |
1142 | pending_complete(pe, success); |
1143 | } | |
1144 | ||
1145 | /* | |
1146 | * Called when the copy I/O has finished. kcopyd actually runs | |
1147 | * this code so don't block. | |
1148 | */ | |
4cdc1d1f | 1149 | static void copy_callback(int read_err, unsigned long write_err, void *context) |
1da177e4 | 1150 | { |
028867ac | 1151 | struct dm_snap_pending_exception *pe = context; |
1da177e4 LT |
1152 | struct dm_snapshot *s = pe->snap; |
1153 | ||
1154 | if (read_err || write_err) | |
1155 | pending_complete(pe, 0); | |
1156 | ||
1157 | else | |
1158 | /* Update the metadata if we are persistent */ | |
493df71c JB |
1159 | s->store->type->commit_exception(s->store, &pe->e, |
1160 | commit_callback, pe); | |
1da177e4 LT |
1161 | } |
1162 | ||
1163 | /* | |
1164 | * Dispatches the copy operation to kcopyd. | |
1165 | */ | |
028867ac | 1166 | static void start_copy(struct dm_snap_pending_exception *pe) |
1da177e4 LT |
1167 | { |
1168 | struct dm_snapshot *s = pe->snap; | |
22a1ceb1 | 1169 | struct dm_io_region src, dest; |
1da177e4 LT |
1170 | struct block_device *bdev = s->origin->bdev; |
1171 | sector_t dev_size; | |
1172 | ||
1173 | dev_size = get_dev_size(bdev); | |
1174 | ||
1175 | src.bdev = bdev; | |
71fab00a | 1176 | src.sector = chunk_to_sector(s->store, pe->e.old_chunk); |
df96eee6 | 1177 | src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector); |
1da177e4 | 1178 | |
fc56f6fb | 1179 | dest.bdev = s->cow->bdev; |
71fab00a | 1180 | dest.sector = chunk_to_sector(s->store, pe->e.new_chunk); |
1da177e4 LT |
1181 | dest.count = src.count; |
1182 | ||
1183 | /* Hand over to kcopyd */ | |
eb69aca5 | 1184 | dm_kcopyd_copy(s->kcopyd_client, |
1da177e4 LT |
1185 | &src, 1, &dest, 0, copy_callback, pe); |
1186 | } | |
1187 | ||
2913808e MP |
1188 | static struct dm_snap_pending_exception * |
1189 | __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk) | |
1190 | { | |
3510cb94 | 1191 | struct dm_exception *e = dm_lookup_exception(&s->pending, chunk); |
2913808e MP |
1192 | |
1193 | if (!e) | |
1194 | return NULL; | |
1195 | ||
1196 | return container_of(e, struct dm_snap_pending_exception, e); | |
1197 | } | |
1198 | ||
1da177e4 LT |
1199 | /* |
1200 | * Looks to see if this snapshot already has a pending exception | |
1201 | * for this chunk, otherwise it allocates a new one and inserts | |
1202 | * it into the pending table. | |
1203 | * | |
1204 | * NOTE: a write lock must be held on snap->lock before calling | |
1205 | * this. | |
1206 | */ | |
028867ac | 1207 | static struct dm_snap_pending_exception * |
c6621392 MP |
1208 | __find_pending_exception(struct dm_snapshot *s, |
1209 | struct dm_snap_pending_exception *pe, chunk_t chunk) | |
1da177e4 | 1210 | { |
c6621392 | 1211 | struct dm_snap_pending_exception *pe2; |
1da177e4 | 1212 | |
2913808e MP |
1213 | pe2 = __lookup_pending_exception(s, chunk); |
1214 | if (pe2) { | |
76df1c65 | 1215 | free_pending_exception(pe); |
2913808e | 1216 | return pe2; |
1da177e4 LT |
1217 | } |
1218 | ||
76df1c65 AK |
1219 | pe->e.old_chunk = chunk; |
1220 | bio_list_init(&pe->origin_bios); | |
1221 | bio_list_init(&pe->snapshot_bios); | |
76df1c65 AK |
1222 | pe->started = 0; |
1223 | ||
493df71c | 1224 | if (s->store->type->prepare_exception(s->store, &pe->e)) { |
76df1c65 AK |
1225 | free_pending_exception(pe); |
1226 | return NULL; | |
1227 | } | |
1228 | ||
3510cb94 | 1229 | dm_insert_exception(&s->pending, &pe->e); |
76df1c65 | 1230 | |
1da177e4 LT |
1231 | return pe; |
1232 | } | |
1233 | ||
1d4989c8 | 1234 | static void remap_exception(struct dm_snapshot *s, struct dm_exception *e, |
d74f81f8 | 1235 | struct bio *bio, chunk_t chunk) |
1da177e4 | 1236 | { |
fc56f6fb | 1237 | bio->bi_bdev = s->cow->bdev; |
71fab00a JB |
1238 | bio->bi_sector = chunk_to_sector(s->store, |
1239 | dm_chunk_number(e->new_chunk) + | |
1240 | (chunk - e->old_chunk)) + | |
1241 | (bio->bi_sector & | |
1242 | s->store->chunk_mask); | |
1da177e4 LT |
1243 | } |
1244 | ||
1245 | static int snapshot_map(struct dm_target *ti, struct bio *bio, | |
1246 | union map_info *map_context) | |
1247 | { | |
1d4989c8 | 1248 | struct dm_exception *e; |
028867ac | 1249 | struct dm_snapshot *s = ti->private; |
d2a7ad29 | 1250 | int r = DM_MAPIO_REMAPPED; |
1da177e4 | 1251 | chunk_t chunk; |
028867ac | 1252 | struct dm_snap_pending_exception *pe = NULL; |
1da177e4 | 1253 | |
494b3ee7 | 1254 | if (unlikely(bio_empty_barrier(bio))) { |
fc56f6fb | 1255 | bio->bi_bdev = s->cow->bdev; |
494b3ee7 MP |
1256 | return DM_MAPIO_REMAPPED; |
1257 | } | |
1258 | ||
71fab00a | 1259 | chunk = sector_to_chunk(s->store, bio->bi_sector); |
1da177e4 LT |
1260 | |
1261 | /* Full snapshots are not usable */ | |
76df1c65 | 1262 | /* To get here the table must be live so s->active is always set. */ |
1da177e4 | 1263 | if (!s->valid) |
f6a80ea8 | 1264 | return -EIO; |
1da177e4 | 1265 | |
ba40a2aa AK |
1266 | /* FIXME: should only take write lock if we need |
1267 | * to copy an exception */ | |
1268 | down_write(&s->lock); | |
1269 | ||
1270 | if (!s->valid) { | |
1271 | r = -EIO; | |
1272 | goto out_unlock; | |
1273 | } | |
1274 | ||
1275 | /* If the block is already remapped - use that, else remap it */ | |
3510cb94 | 1276 | e = dm_lookup_exception(&s->complete, chunk); |
ba40a2aa | 1277 | if (e) { |
d74f81f8 | 1278 | remap_exception(s, e, bio, chunk); |
ba40a2aa AK |
1279 | goto out_unlock; |
1280 | } | |
1281 | ||
1da177e4 LT |
1282 | /* |
1283 | * Write to snapshot - higher level takes care of RW/RO | |
1284 | * flags so we should only get this if we are | |
1285 | * writeable. | |
1286 | */ | |
1287 | if (bio_rw(bio) == WRITE) { | |
2913808e | 1288 | pe = __lookup_pending_exception(s, chunk); |
76df1c65 | 1289 | if (!pe) { |
c6621392 MP |
1290 | up_write(&s->lock); |
1291 | pe = alloc_pending_exception(s); | |
1292 | down_write(&s->lock); | |
1293 | ||
1294 | if (!s->valid) { | |
1295 | free_pending_exception(pe); | |
1296 | r = -EIO; | |
1297 | goto out_unlock; | |
1298 | } | |
1299 | ||
3510cb94 | 1300 | e = dm_lookup_exception(&s->complete, chunk); |
35bf659b MP |
1301 | if (e) { |
1302 | free_pending_exception(pe); | |
1303 | remap_exception(s, e, bio, chunk); | |
1304 | goto out_unlock; | |
1305 | } | |
1306 | ||
c6621392 | 1307 | pe = __find_pending_exception(s, pe, chunk); |
2913808e MP |
1308 | if (!pe) { |
1309 | __invalidate_snapshot(s, -ENOMEM); | |
1310 | r = -EIO; | |
1311 | goto out_unlock; | |
1312 | } | |
1da177e4 LT |
1313 | } |
1314 | ||
d74f81f8 | 1315 | remap_exception(s, &pe->e, bio, chunk); |
76df1c65 AK |
1316 | bio_list_add(&pe->snapshot_bios, bio); |
1317 | ||
d2a7ad29 | 1318 | r = DM_MAPIO_SUBMITTED; |
ba40a2aa | 1319 | |
76df1c65 AK |
1320 | if (!pe->started) { |
1321 | /* this is protected by snap->lock */ | |
1322 | pe->started = 1; | |
ba40a2aa | 1323 | up_write(&s->lock); |
76df1c65 | 1324 | start_copy(pe); |
ba40a2aa AK |
1325 | goto out; |
1326 | } | |
cd45daff | 1327 | } else { |
ba40a2aa | 1328 | bio->bi_bdev = s->origin->bdev; |
cd45daff MP |
1329 | map_context->ptr = track_chunk(s, chunk); |
1330 | } | |
1da177e4 | 1331 | |
ba40a2aa AK |
1332 | out_unlock: |
1333 | up_write(&s->lock); | |
1334 | out: | |
1da177e4 LT |
1335 | return r; |
1336 | } | |
1337 | ||
3452c2a1 MP |
1338 | /* |
1339 | * A snapshot-merge target behaves like a combination of a snapshot | |
1340 | * target and a snapshot-origin target. It only generates new | |
1341 | * exceptions in other snapshots and not in the one that is being | |
1342 | * merged. | |
1343 | * | |
1344 | * For each chunk, if there is an existing exception, it is used to | |
1345 | * redirect I/O to the cow device. Otherwise I/O is sent to the origin, | |
1346 | * which in turn might generate exceptions in other snapshots. | |
1347 | */ | |
1348 | static int snapshot_merge_map(struct dm_target *ti, struct bio *bio, | |
1349 | union map_info *map_context) | |
1350 | { | |
1351 | struct dm_exception *e; | |
1352 | struct dm_snapshot *s = ti->private; | |
1353 | int r = DM_MAPIO_REMAPPED; | |
1354 | chunk_t chunk; | |
1355 | ||
10b8106a MS |
1356 | if (unlikely(bio_empty_barrier(bio))) { |
1357 | if (!map_context->flush_request) | |
1358 | bio->bi_bdev = s->origin->bdev; | |
1359 | else | |
1360 | bio->bi_bdev = s->cow->bdev; | |
1361 | map_context->ptr = NULL; | |
1362 | return DM_MAPIO_REMAPPED; | |
1363 | } | |
1364 | ||
3452c2a1 MP |
1365 | chunk = sector_to_chunk(s->store, bio->bi_sector); |
1366 | ||
1367 | down_read(&s->lock); | |
1368 | ||
1369 | /* Full snapshots are not usable */ | |
1370 | if (!s->valid) { | |
1371 | r = -EIO; | |
1372 | goto out_unlock; | |
1373 | } | |
1374 | ||
1375 | /* If the block is already remapped - use that */ | |
1376 | e = dm_lookup_exception(&s->complete, chunk); | |
1377 | if (e) { | |
1378 | remap_exception(s, e, bio, chunk); | |
1379 | goto out_unlock; | |
1380 | } | |
1381 | ||
1382 | bio->bi_bdev = s->origin->bdev; | |
1383 | ||
1384 | if (bio_rw(bio) == WRITE) { | |
1385 | up_read(&s->lock); | |
1386 | return do_origin(s->origin, bio); | |
1387 | } | |
1388 | ||
1389 | out_unlock: | |
1390 | up_read(&s->lock); | |
1391 | ||
1392 | return r; | |
1393 | } | |
1394 | ||
cd45daff MP |
1395 | static int snapshot_end_io(struct dm_target *ti, struct bio *bio, |
1396 | int error, union map_info *map_context) | |
1397 | { | |
1398 | struct dm_snapshot *s = ti->private; | |
1399 | struct dm_snap_tracked_chunk *c = map_context->ptr; | |
1400 | ||
1401 | if (c) | |
1402 | stop_tracking_chunk(s, c); | |
1403 | ||
1404 | return 0; | |
1405 | } | |
1406 | ||
c26655ca MS |
1407 | static void snapshot_postsuspend(struct dm_target *ti) |
1408 | { | |
1409 | struct dm_snapshot *s = ti->private; | |
1410 | ||
1411 | down_write(&s->lock); | |
1412 | s->suspended = 1; | |
1413 | up_write(&s->lock); | |
1414 | } | |
1415 | ||
c1f0c183 MS |
1416 | static int snapshot_preresume(struct dm_target *ti) |
1417 | { | |
1418 | int r = 0; | |
1419 | struct dm_snapshot *s = ti->private; | |
1420 | struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; | |
1421 | ||
1422 | down_read(&_origins_lock); | |
9d3b15c4 | 1423 | (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); |
c1f0c183 MS |
1424 | if (snap_src && snap_dest) { |
1425 | down_read(&snap_src->lock); | |
1426 | if (s == snap_src) { | |
1427 | DMERR("Unable to resume snapshot source until " | |
1428 | "handover completes."); | |
1429 | r = -EINVAL; | |
1430 | } else if (!snap_src->suspended) { | |
1431 | DMERR("Unable to perform snapshot handover until " | |
1432 | "source is suspended."); | |
1433 | r = -EINVAL; | |
1434 | } | |
1435 | up_read(&snap_src->lock); | |
1436 | } | |
1437 | up_read(&_origins_lock); | |
1438 | ||
1439 | return r; | |
1440 | } | |
1441 | ||
1da177e4 LT |
1442 | static void snapshot_resume(struct dm_target *ti) |
1443 | { | |
028867ac | 1444 | struct dm_snapshot *s = ti->private; |
c1f0c183 MS |
1445 | struct dm_snapshot *snap_src = NULL, *snap_dest = NULL; |
1446 | ||
1447 | down_read(&_origins_lock); | |
9d3b15c4 | 1448 | (void) __find_snapshots_sharing_cow(s, &snap_src, &snap_dest, NULL); |
c1f0c183 MS |
1449 | if (snap_src && snap_dest) { |
1450 | down_write(&snap_src->lock); | |
1451 | down_write_nested(&snap_dest->lock, SINGLE_DEPTH_NESTING); | |
1452 | __handover_exceptions(snap_src, snap_dest); | |
1453 | up_write(&snap_dest->lock); | |
1454 | up_write(&snap_src->lock); | |
1455 | } | |
1456 | up_read(&_origins_lock); | |
1457 | ||
1458 | /* Now we have correct chunk size, reregister */ | |
1459 | reregister_snapshot(s); | |
1da177e4 | 1460 | |
aa14edeb AK |
1461 | down_write(&s->lock); |
1462 | s->active = 1; | |
c26655ca | 1463 | s->suspended = 0; |
aa14edeb | 1464 | up_write(&s->lock); |
1da177e4 LT |
1465 | } |
1466 | ||
1467 | static int snapshot_status(struct dm_target *ti, status_type_t type, | |
1468 | char *result, unsigned int maxlen) | |
1469 | { | |
2e4a31df | 1470 | unsigned sz = 0; |
028867ac | 1471 | struct dm_snapshot *snap = ti->private; |
1da177e4 LT |
1472 | |
1473 | switch (type) { | |
1474 | case STATUSTYPE_INFO: | |
94e76572 MP |
1475 | |
1476 | down_write(&snap->lock); | |
1477 | ||
1da177e4 | 1478 | if (!snap->valid) |
2e4a31df | 1479 | DMEMIT("Invalid"); |
1da177e4 | 1480 | else { |
985903bb MS |
1481 | if (snap->store->type->usage) { |
1482 | sector_t total_sectors, sectors_allocated, | |
1483 | metadata_sectors; | |
1484 | snap->store->type->usage(snap->store, | |
1485 | &total_sectors, | |
1486 | §ors_allocated, | |
1487 | &metadata_sectors); | |
1488 | DMEMIT("%llu/%llu %llu", | |
1489 | (unsigned long long)sectors_allocated, | |
1490 | (unsigned long long)total_sectors, | |
1491 | (unsigned long long)metadata_sectors); | |
1da177e4 LT |
1492 | } |
1493 | else | |
2e4a31df | 1494 | DMEMIT("Unknown"); |
1da177e4 | 1495 | } |
94e76572 MP |
1496 | |
1497 | up_write(&snap->lock); | |
1498 | ||
1da177e4 LT |
1499 | break; |
1500 | ||
1501 | case STATUSTYPE_TABLE: | |
1502 | /* | |
1503 | * kdevname returns a static pointer so we need | |
1504 | * to make private copies if the output is to | |
1505 | * make sense. | |
1506 | */ | |
fc56f6fb | 1507 | DMEMIT("%s %s", snap->origin->name, snap->cow->name); |
1e302a92 JB |
1508 | snap->store->type->status(snap->store, type, result + sz, |
1509 | maxlen - sz); | |
1da177e4 LT |
1510 | break; |
1511 | } | |
1512 | ||
1513 | return 0; | |
1514 | } | |
1515 | ||
8811f46c MS |
1516 | static int snapshot_iterate_devices(struct dm_target *ti, |
1517 | iterate_devices_callout_fn fn, void *data) | |
1518 | { | |
1519 | struct dm_snapshot *snap = ti->private; | |
1520 | ||
1521 | return fn(ti, snap->origin, 0, ti->len, data); | |
1522 | } | |
1523 | ||
1524 | ||
1da177e4 LT |
1525 | /*----------------------------------------------------------------- |
1526 | * Origin methods | |
1527 | *---------------------------------------------------------------*/ | |
9eaae8ff MP |
1528 | |
1529 | /* | |
1530 | * If no exceptions need creating, DM_MAPIO_REMAPPED is returned and any | |
1531 | * supplied bio was ignored. The caller may submit it immediately. | |
1532 | * (No remapping actually occurs as the origin is always a direct linear | |
1533 | * map.) | |
1534 | * | |
1535 | * If further exceptions are required, DM_MAPIO_SUBMITTED is returned | |
1536 | * and any supplied bio is added to a list to be submitted once all | |
1537 | * the necessary exceptions exist. | |
1538 | */ | |
1539 | static int __origin_write(struct list_head *snapshots, sector_t sector, | |
1540 | struct bio *bio) | |
1da177e4 | 1541 | { |
515ad66c | 1542 | int r = DM_MAPIO_REMAPPED; |
1da177e4 | 1543 | struct dm_snapshot *snap; |
1d4989c8 | 1544 | struct dm_exception *e; |
515ad66c MP |
1545 | struct dm_snap_pending_exception *pe; |
1546 | struct dm_snap_pending_exception *pe_to_start_now = NULL; | |
1547 | struct dm_snap_pending_exception *pe_to_start_last = NULL; | |
1da177e4 LT |
1548 | chunk_t chunk; |
1549 | ||
1550 | /* Do all the snapshots on this origin */ | |
1551 | list_for_each_entry (snap, snapshots, list) { | |
3452c2a1 MP |
1552 | /* |
1553 | * Don't make new exceptions in a merging snapshot | |
1554 | * because it has effectively been deleted | |
1555 | */ | |
1556 | if (dm_target_is_snapshot_merge(snap->ti)) | |
1557 | continue; | |
1558 | ||
76df1c65 AK |
1559 | down_write(&snap->lock); |
1560 | ||
aa14edeb AK |
1561 | /* Only deal with valid and active snapshots */ |
1562 | if (!snap->valid || !snap->active) | |
76df1c65 | 1563 | goto next_snapshot; |
1da177e4 | 1564 | |
d5e404c1 | 1565 | /* Nothing to do if writing beyond end of snapshot */ |
9eaae8ff | 1566 | if (sector >= dm_table_get_size(snap->ti->table)) |
76df1c65 | 1567 | goto next_snapshot; |
1da177e4 LT |
1568 | |
1569 | /* | |
1570 | * Remember, different snapshots can have | |
1571 | * different chunk sizes. | |
1572 | */ | |
9eaae8ff | 1573 | chunk = sector_to_chunk(snap->store, sector); |
1da177e4 LT |
1574 | |
1575 | /* | |
1576 | * Check exception table to see if block | |
1577 | * is already remapped in this snapshot | |
1578 | * and trigger an exception if not. | |
1579 | */ | |
3510cb94 | 1580 | e = dm_lookup_exception(&snap->complete, chunk); |
76df1c65 AK |
1581 | if (e) |
1582 | goto next_snapshot; | |
1583 | ||
2913808e | 1584 | pe = __lookup_pending_exception(snap, chunk); |
76df1c65 | 1585 | if (!pe) { |
c6621392 MP |
1586 | up_write(&snap->lock); |
1587 | pe = alloc_pending_exception(snap); | |
1588 | down_write(&snap->lock); | |
1589 | ||
1590 | if (!snap->valid) { | |
1591 | free_pending_exception(pe); | |
1592 | goto next_snapshot; | |
1593 | } | |
1594 | ||
3510cb94 | 1595 | e = dm_lookup_exception(&snap->complete, chunk); |
35bf659b MP |
1596 | if (e) { |
1597 | free_pending_exception(pe); | |
1598 | goto next_snapshot; | |
1599 | } | |
1600 | ||
c6621392 | 1601 | pe = __find_pending_exception(snap, pe, chunk); |
2913808e MP |
1602 | if (!pe) { |
1603 | __invalidate_snapshot(snap, -ENOMEM); | |
1604 | goto next_snapshot; | |
1605 | } | |
76df1c65 AK |
1606 | } |
1607 | ||
515ad66c | 1608 | r = DM_MAPIO_SUBMITTED; |
76df1c65 | 1609 | |
515ad66c MP |
1610 | /* |
1611 | * If an origin bio was supplied, queue it to wait for the | |
1612 | * completion of this exception, and start this one last, | |
1613 | * at the end of the function. | |
1614 | */ | |
1615 | if (bio) { | |
1616 | bio_list_add(&pe->origin_bios, bio); | |
1617 | bio = NULL; | |
76df1c65 | 1618 | |
515ad66c MP |
1619 | if (!pe->started) { |
1620 | pe->started = 1; | |
1621 | pe_to_start_last = pe; | |
1622 | } | |
76df1c65 AK |
1623 | } |
1624 | ||
1625 | if (!pe->started) { | |
1626 | pe->started = 1; | |
515ad66c | 1627 | pe_to_start_now = pe; |
1da177e4 LT |
1628 | } |
1629 | ||
76df1c65 | 1630 | next_snapshot: |
1da177e4 | 1631 | up_write(&snap->lock); |
1da177e4 | 1632 | |
515ad66c MP |
1633 | if (pe_to_start_now) { |
1634 | start_copy(pe_to_start_now); | |
1635 | pe_to_start_now = NULL; | |
1636 | } | |
b4b610f6 AK |
1637 | } |
1638 | ||
1da177e4 | 1639 | /* |
515ad66c MP |
1640 | * Submit the exception against which the bio is queued last, |
1641 | * to give the other exceptions a head start. | |
1da177e4 | 1642 | */ |
515ad66c MP |
1643 | if (pe_to_start_last) |
1644 | start_copy(pe_to_start_last); | |
1da177e4 LT |
1645 | |
1646 | return r; | |
1647 | } | |
1648 | ||
1649 | /* | |
1650 | * Called on a write from the origin driver. | |
1651 | */ | |
1652 | static int do_origin(struct dm_dev *origin, struct bio *bio) | |
1653 | { | |
1654 | struct origin *o; | |
d2a7ad29 | 1655 | int r = DM_MAPIO_REMAPPED; |
1da177e4 LT |
1656 | |
1657 | down_read(&_origins_lock); | |
1658 | o = __lookup_origin(origin->bdev); | |
1659 | if (o) | |
9eaae8ff | 1660 | r = __origin_write(&o->snapshots, bio->bi_sector, bio); |
1da177e4 LT |
1661 | up_read(&_origins_lock); |
1662 | ||
1663 | return r; | |
1664 | } | |
1665 | ||
1666 | /* | |
1667 | * Origin: maps a linear range of a device, with hooks for snapshotting. | |
1668 | */ | |
1669 | ||
1670 | /* | |
1671 | * Construct an origin mapping: <dev_path> | |
1672 | * The context for an origin is merely a 'struct dm_dev *' | |
1673 | * pointing to the real device. | |
1674 | */ | |
1675 | static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv) | |
1676 | { | |
1677 | int r; | |
1678 | struct dm_dev *dev; | |
1679 | ||
1680 | if (argc != 1) { | |
72d94861 | 1681 | ti->error = "origin: incorrect number of arguments"; |
1da177e4 LT |
1682 | return -EINVAL; |
1683 | } | |
1684 | ||
1685 | r = dm_get_device(ti, argv[0], 0, ti->len, | |
1686 | dm_table_get_mode(ti->table), &dev); | |
1687 | if (r) { | |
1688 | ti->error = "Cannot get target device"; | |
1689 | return r; | |
1690 | } | |
1691 | ||
1692 | ti->private = dev; | |
494b3ee7 MP |
1693 | ti->num_flush_requests = 1; |
1694 | ||
1da177e4 LT |
1695 | return 0; |
1696 | } | |
1697 | ||
1698 | static void origin_dtr(struct dm_target *ti) | |
1699 | { | |
028867ac | 1700 | struct dm_dev *dev = ti->private; |
1da177e4 LT |
1701 | dm_put_device(ti, dev); |
1702 | } | |
1703 | ||
1704 | static int origin_map(struct dm_target *ti, struct bio *bio, | |
1705 | union map_info *map_context) | |
1706 | { | |
028867ac | 1707 | struct dm_dev *dev = ti->private; |
1da177e4 LT |
1708 | bio->bi_bdev = dev->bdev; |
1709 | ||
494b3ee7 MP |
1710 | if (unlikely(bio_empty_barrier(bio))) |
1711 | return DM_MAPIO_REMAPPED; | |
1712 | ||
1da177e4 | 1713 | /* Only tell snapshots if this is a write */ |
d2a7ad29 | 1714 | return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED; |
1da177e4 LT |
1715 | } |
1716 | ||
1da177e4 LT |
1717 | /* |
1718 | * Set the target "split_io" field to the minimum of all the snapshots' | |
1719 | * chunk sizes. | |
1720 | */ | |
1721 | static void origin_resume(struct dm_target *ti) | |
1722 | { | |
028867ac | 1723 | struct dm_dev *dev = ti->private; |
1da177e4 LT |
1724 | |
1725 | down_read(&_origins_lock); | |
1da177e4 | 1726 | |
7e201b35 MP |
1727 | ti->split_io = __minimum_chunk_size(__lookup_origin(dev->bdev)); |
1728 | ||
1729 | up_read(&_origins_lock); | |
1da177e4 LT |
1730 | } |
1731 | ||
1732 | static int origin_status(struct dm_target *ti, status_type_t type, char *result, | |
1733 | unsigned int maxlen) | |
1734 | { | |
028867ac | 1735 | struct dm_dev *dev = ti->private; |
1da177e4 LT |
1736 | |
1737 | switch (type) { | |
1738 | case STATUSTYPE_INFO: | |
1739 | result[0] = '\0'; | |
1740 | break; | |
1741 | ||
1742 | case STATUSTYPE_TABLE: | |
1743 | snprintf(result, maxlen, "%s", dev->name); | |
1744 | break; | |
1745 | } | |
1746 | ||
1747 | return 0; | |
1748 | } | |
1749 | ||
8811f46c MS |
1750 | static int origin_iterate_devices(struct dm_target *ti, |
1751 | iterate_devices_callout_fn fn, void *data) | |
1752 | { | |
1753 | struct dm_dev *dev = ti->private; | |
1754 | ||
1755 | return fn(ti, dev, 0, ti->len, data); | |
1756 | } | |
1757 | ||
1da177e4 LT |
1758 | static struct target_type origin_target = { |
1759 | .name = "snapshot-origin", | |
8811f46c | 1760 | .version = {1, 7, 0}, |
1da177e4 LT |
1761 | .module = THIS_MODULE, |
1762 | .ctr = origin_ctr, | |
1763 | .dtr = origin_dtr, | |
1764 | .map = origin_map, | |
1765 | .resume = origin_resume, | |
1766 | .status = origin_status, | |
8811f46c | 1767 | .iterate_devices = origin_iterate_devices, |
1da177e4 LT |
1768 | }; |
1769 | ||
1770 | static struct target_type snapshot_target = { | |
1771 | .name = "snapshot", | |
c26655ca | 1772 | .version = {1, 9, 0}, |
1da177e4 LT |
1773 | .module = THIS_MODULE, |
1774 | .ctr = snapshot_ctr, | |
1775 | .dtr = snapshot_dtr, | |
1776 | .map = snapshot_map, | |
cd45daff | 1777 | .end_io = snapshot_end_io, |
c26655ca | 1778 | .postsuspend = snapshot_postsuspend, |
c1f0c183 | 1779 | .preresume = snapshot_preresume, |
1da177e4 LT |
1780 | .resume = snapshot_resume, |
1781 | .status = snapshot_status, | |
8811f46c | 1782 | .iterate_devices = snapshot_iterate_devices, |
1da177e4 LT |
1783 | }; |
1784 | ||
d698aa45 MP |
1785 | static struct target_type merge_target = { |
1786 | .name = dm_snapshot_merge_target_name, | |
1787 | .version = {1, 0, 0}, | |
1788 | .module = THIS_MODULE, | |
1789 | .ctr = snapshot_ctr, | |
1790 | .dtr = snapshot_dtr, | |
3452c2a1 | 1791 | .map = snapshot_merge_map, |
d698aa45 MP |
1792 | .end_io = snapshot_end_io, |
1793 | .postsuspend = snapshot_postsuspend, | |
1794 | .preresume = snapshot_preresume, | |
1795 | .resume = snapshot_resume, | |
1796 | .status = snapshot_status, | |
1797 | .iterate_devices = snapshot_iterate_devices, | |
1798 | }; | |
1799 | ||
1da177e4 LT |
1800 | static int __init dm_snapshot_init(void) |
1801 | { | |
1802 | int r; | |
1803 | ||
4db6bfe0 AK |
1804 | r = dm_exception_store_init(); |
1805 | if (r) { | |
1806 | DMERR("Failed to initialize exception stores"); | |
1807 | return r; | |
1808 | } | |
1809 | ||
1da177e4 | 1810 | r = dm_register_target(&snapshot_target); |
d698aa45 | 1811 | if (r < 0) { |
1da177e4 | 1812 | DMERR("snapshot target register failed %d", r); |
034a186d | 1813 | goto bad_register_snapshot_target; |
1da177e4 LT |
1814 | } |
1815 | ||
1816 | r = dm_register_target(&origin_target); | |
1817 | if (r < 0) { | |
72d94861 | 1818 | DMERR("Origin target register failed %d", r); |
d698aa45 MP |
1819 | goto bad_register_origin_target; |
1820 | } | |
1821 | ||
1822 | r = dm_register_target(&merge_target); | |
1823 | if (r < 0) { | |
1824 | DMERR("Merge target register failed %d", r); | |
1825 | goto bad_register_merge_target; | |
1da177e4 LT |
1826 | } |
1827 | ||
1828 | r = init_origin_hash(); | |
1829 | if (r) { | |
1830 | DMERR("init_origin_hash failed."); | |
d698aa45 | 1831 | goto bad_origin_hash; |
1da177e4 LT |
1832 | } |
1833 | ||
1d4989c8 | 1834 | exception_cache = KMEM_CACHE(dm_exception, 0); |
1da177e4 LT |
1835 | if (!exception_cache) { |
1836 | DMERR("Couldn't create exception cache."); | |
1837 | r = -ENOMEM; | |
d698aa45 | 1838 | goto bad_exception_cache; |
1da177e4 LT |
1839 | } |
1840 | ||
028867ac | 1841 | pending_cache = KMEM_CACHE(dm_snap_pending_exception, 0); |
1da177e4 LT |
1842 | if (!pending_cache) { |
1843 | DMERR("Couldn't create pending cache."); | |
1844 | r = -ENOMEM; | |
d698aa45 | 1845 | goto bad_pending_cache; |
1da177e4 LT |
1846 | } |
1847 | ||
cd45daff MP |
1848 | tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0); |
1849 | if (!tracked_chunk_cache) { | |
1850 | DMERR("Couldn't create cache to track chunks in use."); | |
1851 | r = -ENOMEM; | |
d698aa45 | 1852 | goto bad_tracked_chunk_cache; |
cd45daff MP |
1853 | } |
1854 | ||
ca3a931f AK |
1855 | ksnapd = create_singlethread_workqueue("ksnapd"); |
1856 | if (!ksnapd) { | |
1857 | DMERR("Failed to create ksnapd workqueue."); | |
1858 | r = -ENOMEM; | |
92e86812 | 1859 | goto bad_pending_pool; |
ca3a931f AK |
1860 | } |
1861 | ||
1da177e4 LT |
1862 | return 0; |
1863 | ||
4db6bfe0 | 1864 | bad_pending_pool: |
cd45daff | 1865 | kmem_cache_destroy(tracked_chunk_cache); |
d698aa45 | 1866 | bad_tracked_chunk_cache: |
1da177e4 | 1867 | kmem_cache_destroy(pending_cache); |
d698aa45 | 1868 | bad_pending_cache: |
1da177e4 | 1869 | kmem_cache_destroy(exception_cache); |
d698aa45 | 1870 | bad_exception_cache: |
1da177e4 | 1871 | exit_origin_hash(); |
d698aa45 MP |
1872 | bad_origin_hash: |
1873 | dm_unregister_target(&merge_target); | |
1874 | bad_register_merge_target: | |
1da177e4 | 1875 | dm_unregister_target(&origin_target); |
d698aa45 | 1876 | bad_register_origin_target: |
1da177e4 | 1877 | dm_unregister_target(&snapshot_target); |
034a186d JB |
1878 | bad_register_snapshot_target: |
1879 | dm_exception_store_exit(); | |
d698aa45 | 1880 | |
1da177e4 LT |
1881 | return r; |
1882 | } | |
1883 | ||
1884 | static void __exit dm_snapshot_exit(void) | |
1885 | { | |
ca3a931f AK |
1886 | destroy_workqueue(ksnapd); |
1887 | ||
10d3bd09 MP |
1888 | dm_unregister_target(&snapshot_target); |
1889 | dm_unregister_target(&origin_target); | |
d698aa45 | 1890 | dm_unregister_target(&merge_target); |
1da177e4 LT |
1891 | |
1892 | exit_origin_hash(); | |
1da177e4 LT |
1893 | kmem_cache_destroy(pending_cache); |
1894 | kmem_cache_destroy(exception_cache); | |
cd45daff | 1895 | kmem_cache_destroy(tracked_chunk_cache); |
4db6bfe0 AK |
1896 | |
1897 | dm_exception_store_exit(); | |
1da177e4 LT |
1898 | } |
1899 | ||
1900 | /* Module hooks */ | |
1901 | module_init(dm_snapshot_init); | |
1902 | module_exit(dm_snapshot_exit); | |
1903 | ||
1904 | MODULE_DESCRIPTION(DM_NAME " snapshot target"); | |
1905 | MODULE_AUTHOR("Joe Thornber"); | |
1906 | MODULE_LICENSE("GPL"); |