Commit | Line | Data |
---|---|---|
3241b1d3 JT |
1 | /* |
2 | * Copyright (C) 2011 Red Hat, Inc. | |
3 | * | |
4 | * This file is released under the GPL. | |
5 | */ | |
6 | #include "dm-block-manager.h" | |
7 | #include "dm-persistent-data-internal.h" | |
3241b1d3 | 8 | |
afa53df8 | 9 | #include <linux/dm-bufio.h> |
3241b1d3 JT |
10 | #include <linux/crc32c.h> |
11 | #include <linux/module.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/rwsem.h> | |
14 | #include <linux/device-mapper.h> | |
15 | #include <linux/stacktrace.h> | |
0881e7bd | 16 | #include <linux/sched/task.h> |
3241b1d3 JT |
17 | |
18 | #define DM_MSG_PREFIX "block manager" | |
19 | ||
20 | /*----------------------------------------------------------------*/ | |
21 | ||
2e8ed711 JT |
22 | #ifdef CONFIG_DM_DEBUG_BLOCK_MANAGER_LOCKING |
23 | ||
3241b1d3 JT |
24 | /* |
25 | * This is a read/write semaphore with a couple of differences. | |
26 | * | |
27 | * i) There is a restriction on the number of concurrent read locks that | |
28 | * may be held at once. This is just an implementation detail. | |
29 | * | |
30 | * ii) Recursive locking attempts are detected and return EINVAL. A stack | |
83f0d77a | 31 | * trace is also emitted for the previous lock acquisition. |
3241b1d3 JT |
32 | * |
33 | * iii) Priority is given to write locks. | |
34 | */ | |
35 | #define MAX_HOLDERS 4 | |
36 | #define MAX_STACK 10 | |
37 | ||
38 | typedef unsigned long stack_entries[MAX_STACK]; | |
39 | ||
40 | struct block_lock { | |
41 | spinlock_t lock; | |
42 | __s32 count; | |
43 | struct list_head waiters; | |
44 | struct task_struct *holders[MAX_HOLDERS]; | |
45 | ||
46 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING | |
47 | struct stack_trace traces[MAX_HOLDERS]; | |
48 | stack_entries entries[MAX_HOLDERS]; | |
49 | #endif | |
50 | }; | |
51 | ||
52 | struct waiter { | |
53 | struct list_head list; | |
54 | struct task_struct *task; | |
55 | int wants_write; | |
56 | }; | |
57 | ||
58 | static unsigned __find_holder(struct block_lock *lock, | |
59 | struct task_struct *task) | |
60 | { | |
61 | unsigned i; | |
62 | ||
63 | for (i = 0; i < MAX_HOLDERS; i++) | |
64 | if (lock->holders[i] == task) | |
65 | break; | |
66 | ||
67 | BUG_ON(i == MAX_HOLDERS); | |
68 | return i; | |
69 | } | |
70 | ||
71 | /* call this *after* you increment lock->count */ | |
72 | static void __add_holder(struct block_lock *lock, struct task_struct *task) | |
73 | { | |
74 | unsigned h = __find_holder(lock, NULL); | |
75 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING | |
76 | struct stack_trace *t; | |
77 | #endif | |
78 | ||
79 | get_task_struct(task); | |
80 | lock->holders[h] = task; | |
81 | ||
82 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING | |
83 | t = lock->traces + h; | |
84 | t->nr_entries = 0; | |
85 | t->max_entries = MAX_STACK; | |
86 | t->entries = lock->entries[h]; | |
87 | t->skip = 2; | |
88 | save_stack_trace(t); | |
89 | #endif | |
90 | } | |
91 | ||
92 | /* call this *before* you decrement lock->count */ | |
93 | static void __del_holder(struct block_lock *lock, struct task_struct *task) | |
94 | { | |
95 | unsigned h = __find_holder(lock, task); | |
96 | lock->holders[h] = NULL; | |
97 | put_task_struct(task); | |
98 | } | |
99 | ||
100 | static int __check_holder(struct block_lock *lock) | |
101 | { | |
102 | unsigned i; | |
3241b1d3 JT |
103 | |
104 | for (i = 0; i < MAX_HOLDERS; i++) { | |
105 | if (lock->holders[i] == current) { | |
10343180 | 106 | DMERR("recursive lock detected in metadata"); |
3241b1d3 JT |
107 | #ifdef CONFIG_DM_DEBUG_BLOCK_STACK_TRACING |
108 | DMERR("previously held here:"); | |
109 | print_stack_trace(lock->traces + i, 4); | |
110 | ||
83f0d77a | 111 | DMERR("subsequent acquisition attempted here:"); |
313c9b97 | 112 | dump_stack(); |
3241b1d3 JT |
113 | #endif |
114 | return -EINVAL; | |
115 | } | |
116 | } | |
117 | ||
118 | return 0; | |
119 | } | |
120 | ||
121 | static void __wait(struct waiter *w) | |
122 | { | |
123 | for (;;) { | |
642fa448 | 124 | set_current_state(TASK_UNINTERRUPTIBLE); |
3241b1d3 JT |
125 | |
126 | if (!w->task) | |
127 | break; | |
128 | ||
129 | schedule(); | |
130 | } | |
131 | ||
642fa448 | 132 | set_current_state(TASK_RUNNING); |
3241b1d3 JT |
133 | } |
134 | ||
135 | static void __wake_waiter(struct waiter *w) | |
136 | { | |
137 | struct task_struct *task; | |
138 | ||
139 | list_del(&w->list); | |
140 | task = w->task; | |
141 | smp_mb(); | |
142 | w->task = NULL; | |
143 | wake_up_process(task); | |
144 | } | |
145 | ||
146 | /* | |
147 | * We either wake a few readers or a single writer. | |
148 | */ | |
149 | static void __wake_many(struct block_lock *lock) | |
150 | { | |
151 | struct waiter *w, *tmp; | |
152 | ||
153 | BUG_ON(lock->count < 0); | |
154 | list_for_each_entry_safe(w, tmp, &lock->waiters, list) { | |
155 | if (lock->count >= MAX_HOLDERS) | |
156 | return; | |
157 | ||
158 | if (w->wants_write) { | |
159 | if (lock->count > 0) | |
160 | return; /* still read locked */ | |
161 | ||
162 | lock->count = -1; | |
163 | __add_holder(lock, w->task); | |
164 | __wake_waiter(w); | |
165 | return; | |
166 | } | |
167 | ||
168 | lock->count++; | |
169 | __add_holder(lock, w->task); | |
170 | __wake_waiter(w); | |
171 | } | |
172 | } | |
173 | ||
174 | static void bl_init(struct block_lock *lock) | |
175 | { | |
176 | int i; | |
177 | ||
178 | spin_lock_init(&lock->lock); | |
179 | lock->count = 0; | |
180 | INIT_LIST_HEAD(&lock->waiters); | |
181 | for (i = 0; i < MAX_HOLDERS; i++) | |
182 | lock->holders[i] = NULL; | |
183 | } | |
184 | ||
185 | static int __available_for_read(struct block_lock *lock) | |
186 | { | |
187 | return lock->count >= 0 && | |
188 | lock->count < MAX_HOLDERS && | |
189 | list_empty(&lock->waiters); | |
190 | } | |
191 | ||
192 | static int bl_down_read(struct block_lock *lock) | |
193 | { | |
194 | int r; | |
195 | struct waiter w; | |
196 | ||
197 | spin_lock(&lock->lock); | |
198 | r = __check_holder(lock); | |
199 | if (r) { | |
200 | spin_unlock(&lock->lock); | |
201 | return r; | |
202 | } | |
203 | ||
204 | if (__available_for_read(lock)) { | |
205 | lock->count++; | |
206 | __add_holder(lock, current); | |
207 | spin_unlock(&lock->lock); | |
208 | return 0; | |
209 | } | |
210 | ||
211 | get_task_struct(current); | |
212 | ||
213 | w.task = current; | |
214 | w.wants_write = 0; | |
215 | list_add_tail(&w.list, &lock->waiters); | |
216 | spin_unlock(&lock->lock); | |
217 | ||
218 | __wait(&w); | |
219 | put_task_struct(current); | |
220 | return 0; | |
221 | } | |
222 | ||
223 | static int bl_down_read_nonblock(struct block_lock *lock) | |
224 | { | |
225 | int r; | |
226 | ||
227 | spin_lock(&lock->lock); | |
228 | r = __check_holder(lock); | |
229 | if (r) | |
230 | goto out; | |
231 | ||
232 | if (__available_for_read(lock)) { | |
233 | lock->count++; | |
234 | __add_holder(lock, current); | |
235 | r = 0; | |
236 | } else | |
237 | r = -EWOULDBLOCK; | |
238 | ||
239 | out: | |
240 | spin_unlock(&lock->lock); | |
241 | return r; | |
242 | } | |
243 | ||
244 | static void bl_up_read(struct block_lock *lock) | |
245 | { | |
246 | spin_lock(&lock->lock); | |
247 | BUG_ON(lock->count <= 0); | |
248 | __del_holder(lock, current); | |
249 | --lock->count; | |
250 | if (!list_empty(&lock->waiters)) | |
251 | __wake_many(lock); | |
252 | spin_unlock(&lock->lock); | |
253 | } | |
254 | ||
255 | static int bl_down_write(struct block_lock *lock) | |
256 | { | |
257 | int r; | |
258 | struct waiter w; | |
259 | ||
260 | spin_lock(&lock->lock); | |
261 | r = __check_holder(lock); | |
262 | if (r) { | |
263 | spin_unlock(&lock->lock); | |
264 | return r; | |
265 | } | |
266 | ||
267 | if (lock->count == 0 && list_empty(&lock->waiters)) { | |
268 | lock->count = -1; | |
269 | __add_holder(lock, current); | |
270 | spin_unlock(&lock->lock); | |
271 | return 0; | |
272 | } | |
273 | ||
274 | get_task_struct(current); | |
275 | w.task = current; | |
276 | w.wants_write = 1; | |
277 | ||
278 | /* | |
279 | * Writers given priority. We know there's only one mutator in the | |
280 | * system, so ignoring the ordering reversal. | |
281 | */ | |
282 | list_add(&w.list, &lock->waiters); | |
283 | spin_unlock(&lock->lock); | |
284 | ||
285 | __wait(&w); | |
286 | put_task_struct(current); | |
287 | ||
288 | return 0; | |
289 | } | |
290 | ||
291 | static void bl_up_write(struct block_lock *lock) | |
292 | { | |
293 | spin_lock(&lock->lock); | |
294 | __del_holder(lock, current); | |
295 | lock->count = 0; | |
296 | if (!list_empty(&lock->waiters)) | |
297 | __wake_many(lock); | |
298 | spin_unlock(&lock->lock); | |
299 | } | |
300 | ||
301 | static void report_recursive_bug(dm_block_t b, int r) | |
302 | { | |
303 | if (r == -EINVAL) | |
304 | DMERR("recursive acquisition of block %llu requested.", | |
305 | (unsigned long long) b); | |
306 | } | |
307 | ||
2e8ed711 JT |
308 | #else /* !CONFIG_DM_DEBUG_BLOCK_MANAGER_LOCKING */ |
309 | ||
310 | #define bl_init(x) do { } while (0) | |
311 | #define bl_down_read(x) 0 | |
312 | #define bl_down_read_nonblock(x) 0 | |
313 | #define bl_up_read(x) do { } while (0) | |
314 | #define bl_down_write(x) 0 | |
315 | #define bl_up_write(x) do { } while (0) | |
316 | #define report_recursive_bug(x, y) do { } while (0) | |
317 | ||
318 | #endif /* CONFIG_DM_DEBUG_BLOCK_MANAGER_LOCKING */ | |
319 | ||
3241b1d3 JT |
320 | /*----------------------------------------------------------------*/ |
321 | ||
322 | /* | |
323 | * Block manager is currently implemented using dm-bufio. struct | |
324 | * dm_block_manager and struct dm_block map directly onto a couple of | |
325 | * structs in the bufio interface. I want to retain the freedom to move | |
326 | * away from bufio in the future. So these structs are just cast within | |
327 | * this .c file, rather than making it through to the public interface. | |
328 | */ | |
329 | static struct dm_buffer *to_buffer(struct dm_block *b) | |
330 | { | |
331 | return (struct dm_buffer *) b; | |
332 | } | |
333 | ||
3241b1d3 JT |
334 | dm_block_t dm_block_location(struct dm_block *b) |
335 | { | |
336 | return dm_bufio_get_block_number(to_buffer(b)); | |
337 | } | |
338 | EXPORT_SYMBOL_GPL(dm_block_location); | |
339 | ||
340 | void *dm_block_data(struct dm_block *b) | |
341 | { | |
342 | return dm_bufio_get_block_data(to_buffer(b)); | |
343 | } | |
344 | EXPORT_SYMBOL_GPL(dm_block_data); | |
345 | ||
346 | struct buffer_aux { | |
347 | struct dm_block_validator *validator; | |
3241b1d3 | 348 | int write_locked; |
2e8ed711 JT |
349 | |
350 | #ifdef CONFIG_DM_DEBUG_BLOCK_MANAGER_LOCKING | |
351 | struct block_lock lock; | |
352 | #endif | |
3241b1d3 JT |
353 | }; |
354 | ||
355 | static void dm_block_manager_alloc_callback(struct dm_buffer *buf) | |
356 | { | |
357 | struct buffer_aux *aux = dm_bufio_get_aux_data(buf); | |
358 | aux->validator = NULL; | |
359 | bl_init(&aux->lock); | |
360 | } | |
361 | ||
362 | static void dm_block_manager_write_callback(struct dm_buffer *buf) | |
363 | { | |
364 | struct buffer_aux *aux = dm_bufio_get_aux_data(buf); | |
365 | if (aux->validator) { | |
366 | aux->validator->prepare_for_write(aux->validator, (struct dm_block *) buf, | |
367 | dm_bufio_get_block_size(dm_bufio_get_client(buf))); | |
368 | } | |
369 | } | |
370 | ||
371 | /*---------------------------------------------------------------- | |
372 | * Public interface | |
373 | *--------------------------------------------------------------*/ | |
51a0f659 JT |
374 | struct dm_block_manager { |
375 | struct dm_bufio_client *bufio; | |
31097557 | 376 | bool read_only:1; |
51a0f659 JT |
377 | }; |
378 | ||
3241b1d3 JT |
379 | struct dm_block_manager *dm_block_manager_create(struct block_device *bdev, |
380 | unsigned block_size, | |
3241b1d3 JT |
381 | unsigned max_held_per_thread) |
382 | { | |
51a0f659 JT |
383 | int r; |
384 | struct dm_block_manager *bm; | |
385 | ||
386 | bm = kmalloc(sizeof(*bm), GFP_KERNEL); | |
387 | if (!bm) { | |
388 | r = -ENOMEM; | |
389 | goto bad; | |
390 | } | |
391 | ||
392 | bm->bufio = dm_bufio_client_create(bdev, block_size, max_held_per_thread, | |
393 | sizeof(struct buffer_aux), | |
394 | dm_block_manager_alloc_callback, | |
395 | dm_block_manager_write_callback); | |
396 | if (IS_ERR(bm->bufio)) { | |
397 | r = PTR_ERR(bm->bufio); | |
398 | kfree(bm); | |
399 | goto bad; | |
400 | } | |
401 | ||
31097557 JT |
402 | bm->read_only = false; |
403 | ||
51a0f659 JT |
404 | return bm; |
405 | ||
406 | bad: | |
407 | return ERR_PTR(r); | |
3241b1d3 JT |
408 | } |
409 | EXPORT_SYMBOL_GPL(dm_block_manager_create); | |
410 | ||
411 | void dm_block_manager_destroy(struct dm_block_manager *bm) | |
412 | { | |
51a0f659 JT |
413 | dm_bufio_client_destroy(bm->bufio); |
414 | kfree(bm); | |
3241b1d3 JT |
415 | } |
416 | EXPORT_SYMBOL_GPL(dm_block_manager_destroy); | |
417 | ||
418 | unsigned dm_bm_block_size(struct dm_block_manager *bm) | |
419 | { | |
51a0f659 | 420 | return dm_bufio_get_block_size(bm->bufio); |
3241b1d3 JT |
421 | } |
422 | EXPORT_SYMBOL_GPL(dm_bm_block_size); | |
423 | ||
424 | dm_block_t dm_bm_nr_blocks(struct dm_block_manager *bm) | |
425 | { | |
51a0f659 | 426 | return dm_bufio_get_device_size(bm->bufio); |
3241b1d3 JT |
427 | } |
428 | ||
429 | static int dm_bm_validate_buffer(struct dm_block_manager *bm, | |
430 | struct dm_buffer *buf, | |
431 | struct buffer_aux *aux, | |
432 | struct dm_block_validator *v) | |
433 | { | |
434 | if (unlikely(!aux->validator)) { | |
435 | int r; | |
436 | if (!v) | |
437 | return 0; | |
51a0f659 | 438 | r = v->check(v, (struct dm_block *) buf, dm_bufio_get_block_size(bm->bufio)); |
a5bd968a | 439 | if (unlikely(r)) { |
89ddeb8c MS |
440 | DMERR_LIMIT("%s validator check failed for block %llu", v->name, |
441 | (unsigned long long) dm_bufio_get_block_number(buf)); | |
3241b1d3 | 442 | return r; |
a5bd968a | 443 | } |
3241b1d3 JT |
444 | aux->validator = v; |
445 | } else { | |
446 | if (unlikely(aux->validator != v)) { | |
89ddeb8c MS |
447 | DMERR_LIMIT("validator mismatch (old=%s vs new=%s) for block %llu", |
448 | aux->validator->name, v ? v->name : "NULL", | |
449 | (unsigned long long) dm_bufio_get_block_number(buf)); | |
3241b1d3 JT |
450 | return -EINVAL; |
451 | } | |
452 | } | |
453 | ||
454 | return 0; | |
455 | } | |
456 | int dm_bm_read_lock(struct dm_block_manager *bm, dm_block_t b, | |
457 | struct dm_block_validator *v, | |
458 | struct dm_block **result) | |
459 | { | |
460 | struct buffer_aux *aux; | |
461 | void *p; | |
462 | int r; | |
463 | ||
51a0f659 | 464 | p = dm_bufio_read(bm->bufio, b, (struct dm_buffer **) result); |
5941c621 | 465 | if (IS_ERR(p)) |
3241b1d3 JT |
466 | return PTR_ERR(p); |
467 | ||
468 | aux = dm_bufio_get_aux_data(to_buffer(*result)); | |
469 | r = bl_down_read(&aux->lock); | |
470 | if (unlikely(r)) { | |
471 | dm_bufio_release(to_buffer(*result)); | |
472 | report_recursive_bug(b, r); | |
473 | return r; | |
474 | } | |
475 | ||
476 | aux->write_locked = 0; | |
477 | ||
478 | r = dm_bm_validate_buffer(bm, to_buffer(*result), aux, v); | |
479 | if (unlikely(r)) { | |
480 | bl_up_read(&aux->lock); | |
481 | dm_bufio_release(to_buffer(*result)); | |
482 | return r; | |
483 | } | |
484 | ||
485 | return 0; | |
486 | } | |
487 | EXPORT_SYMBOL_GPL(dm_bm_read_lock); | |
488 | ||
489 | int dm_bm_write_lock(struct dm_block_manager *bm, | |
490 | dm_block_t b, struct dm_block_validator *v, | |
491 | struct dm_block **result) | |
492 | { | |
493 | struct buffer_aux *aux; | |
494 | void *p; | |
495 | int r; | |
496 | ||
31097557 JT |
497 | if (bm->read_only) |
498 | return -EPERM; | |
499 | ||
51a0f659 | 500 | p = dm_bufio_read(bm->bufio, b, (struct dm_buffer **) result); |
5941c621 | 501 | if (IS_ERR(p)) |
3241b1d3 JT |
502 | return PTR_ERR(p); |
503 | ||
504 | aux = dm_bufio_get_aux_data(to_buffer(*result)); | |
505 | r = bl_down_write(&aux->lock); | |
506 | if (r) { | |
507 | dm_bufio_release(to_buffer(*result)); | |
508 | report_recursive_bug(b, r); | |
509 | return r; | |
510 | } | |
511 | ||
512 | aux->write_locked = 1; | |
513 | ||
514 | r = dm_bm_validate_buffer(bm, to_buffer(*result), aux, v); | |
515 | if (unlikely(r)) { | |
516 | bl_up_write(&aux->lock); | |
517 | dm_bufio_release(to_buffer(*result)); | |
518 | return r; | |
519 | } | |
520 | ||
521 | return 0; | |
522 | } | |
523 | EXPORT_SYMBOL_GPL(dm_bm_write_lock); | |
524 | ||
525 | int dm_bm_read_try_lock(struct dm_block_manager *bm, | |
526 | dm_block_t b, struct dm_block_validator *v, | |
527 | struct dm_block **result) | |
528 | { | |
529 | struct buffer_aux *aux; | |
530 | void *p; | |
531 | int r; | |
532 | ||
51a0f659 | 533 | p = dm_bufio_get(bm->bufio, b, (struct dm_buffer **) result); |
5941c621 | 534 | if (IS_ERR(p)) |
3241b1d3 JT |
535 | return PTR_ERR(p); |
536 | if (unlikely(!p)) | |
537 | return -EWOULDBLOCK; | |
538 | ||
539 | aux = dm_bufio_get_aux_data(to_buffer(*result)); | |
540 | r = bl_down_read_nonblock(&aux->lock); | |
541 | if (r < 0) { | |
542 | dm_bufio_release(to_buffer(*result)); | |
543 | report_recursive_bug(b, r); | |
544 | return r; | |
545 | } | |
546 | aux->write_locked = 0; | |
547 | ||
548 | r = dm_bm_validate_buffer(bm, to_buffer(*result), aux, v); | |
549 | if (unlikely(r)) { | |
550 | bl_up_read(&aux->lock); | |
551 | dm_bufio_release(to_buffer(*result)); | |
552 | return r; | |
553 | } | |
554 | ||
555 | return 0; | |
556 | } | |
557 | ||
558 | int dm_bm_write_lock_zero(struct dm_block_manager *bm, | |
559 | dm_block_t b, struct dm_block_validator *v, | |
560 | struct dm_block **result) | |
561 | { | |
562 | int r; | |
563 | struct buffer_aux *aux; | |
564 | void *p; | |
565 | ||
31097557 JT |
566 | if (bm->read_only) |
567 | return -EPERM; | |
568 | ||
51a0f659 | 569 | p = dm_bufio_new(bm->bufio, b, (struct dm_buffer **) result); |
5941c621 | 570 | if (IS_ERR(p)) |
3241b1d3 JT |
571 | return PTR_ERR(p); |
572 | ||
573 | memset(p, 0, dm_bm_block_size(bm)); | |
574 | ||
575 | aux = dm_bufio_get_aux_data(to_buffer(*result)); | |
576 | r = bl_down_write(&aux->lock); | |
577 | if (r) { | |
578 | dm_bufio_release(to_buffer(*result)); | |
579 | return r; | |
580 | } | |
581 | ||
582 | aux->write_locked = 1; | |
583 | aux->validator = v; | |
584 | ||
585 | return 0; | |
586 | } | |
384ef0e6 | 587 | EXPORT_SYMBOL_GPL(dm_bm_write_lock_zero); |
3241b1d3 | 588 | |
4c7da06f | 589 | void dm_bm_unlock(struct dm_block *b) |
3241b1d3 JT |
590 | { |
591 | struct buffer_aux *aux; | |
592 | aux = dm_bufio_get_aux_data(to_buffer(b)); | |
593 | ||
594 | if (aux->write_locked) { | |
595 | dm_bufio_mark_buffer_dirty(to_buffer(b)); | |
596 | bl_up_write(&aux->lock); | |
597 | } else | |
598 | bl_up_read(&aux->lock); | |
599 | ||
600 | dm_bufio_release(to_buffer(b)); | |
3241b1d3 JT |
601 | } |
602 | EXPORT_SYMBOL_GPL(dm_bm_unlock); | |
603 | ||
a9d45396 | 604 | int dm_bm_flush(struct dm_block_manager *bm) |
3241b1d3 | 605 | { |
31097557 JT |
606 | if (bm->read_only) |
607 | return -EPERM; | |
608 | ||
51a0f659 | 609 | return dm_bufio_write_dirty_buffers(bm->bufio); |
3241b1d3 | 610 | } |
a9d45396 | 611 | EXPORT_SYMBOL_GPL(dm_bm_flush); |
3241b1d3 | 612 | |
04f17c80 JT |
613 | void dm_bm_prefetch(struct dm_block_manager *bm, dm_block_t b) |
614 | { | |
615 | dm_bufio_prefetch(bm->bufio, b, 1); | |
616 | } | |
617 | ||
49f154c7 MS |
618 | bool dm_bm_is_read_only(struct dm_block_manager *bm) |
619 | { | |
620 | return bm->read_only; | |
621 | } | |
622 | EXPORT_SYMBOL_GPL(dm_bm_is_read_only); | |
623 | ||
31097557 JT |
624 | void dm_bm_set_read_only(struct dm_block_manager *bm) |
625 | { | |
626 | bm->read_only = true; | |
627 | } | |
628 | EXPORT_SYMBOL_GPL(dm_bm_set_read_only); | |
629 | ||
9b7aaa64 JT |
630 | void dm_bm_set_read_write(struct dm_block_manager *bm) |
631 | { | |
632 | bm->read_only = false; | |
633 | } | |
634 | EXPORT_SYMBOL_GPL(dm_bm_set_read_write); | |
635 | ||
3241b1d3 JT |
636 | u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor) |
637 | { | |
638 | return crc32c(~(u32) 0, data, len) ^ init_xor; | |
639 | } | |
640 | EXPORT_SYMBOL_GPL(dm_bm_checksum); | |
641 | ||
642 | /*----------------------------------------------------------------*/ | |
643 | ||
644 | MODULE_LICENSE("GPL"); | |
645 | MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>"); | |
646 | MODULE_DESCRIPTION("Immutable metadata library for dm"); | |
647 | ||
648 | /*----------------------------------------------------------------*/ |