summaryrefslogtreecommitdiff
path: root/drivers/md/persistent-data/dm-transaction-manager.c
blob: d247a35da3c63030bca417b89482bb8fdf371cd0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
/*
 * Copyright (C) 2011 Red Hat, Inc.
 *
 * This file is released under the GPL.
 */
#include "dm-transaction-manager.h"
#include "dm-space-map.h"
#include "dm-space-map-disk.h"
#include "dm-space-map-metadata.h"
#include "dm-persistent-data-internal.h"

#include <linux/export.h>
#include <linux/slab.h>
#include <linux/device-mapper.h>

#define DM_MSG_PREFIX "transaction manager"

/*----------------------------------------------------------------*/

struct shadow_info {
	struct hlist_node hlist;
	dm_block_t where;
};

/*
 * It would be nice if we scaled with the size of transaction.
 */
#define HASH_SIZE 256
#define HASH_MASK (HASH_SIZE - 1)

struct dm_transaction_manager {
	int is_clone;
	struct dm_transaction_manager *real;

	struct dm_block_manager *bm;
	struct dm_space_map *sm;

	spinlock_t lock;
	struct hlist_head buckets[HASH_SIZE];
};

/*----------------------------------------------------------------*/

static int is_shadow(struct dm_transaction_manager *tm, dm_block_t b)
{
	int r = 0;
	unsigned bucket = dm_hash_block(b, HASH_MASK);
	struct shadow_info *si;
	struct hlist_node *n;

	spin_lock(&tm->lock);
	hlist_for_each_entry(si, n, tm->buckets + bucket, hlist)
		if (si->where == b) {
			r = 1;
			break;
		}
	spin_unlock(&tm->lock);

	return r;
}

/*
 * This can silently fail if there's no memory.  We're ok with this since
 * creating redundant shadows causes no harm.
 */
static void insert_shadow(struct dm_transaction_manager *tm, dm_block_t b)
{
	unsigned bucket;
	struct shadow_info *si;

	si = kmalloc(sizeof(*si), GFP_NOIO);
	if (si) {
		si->where = b;
		bucket = dm_hash_block(b, HASH_MASK);
		spin_lock(&tm->lock);
		hlist_add_head(&si->hlist, tm->buckets + bucket);
		spin_unlock(&tm->lock);
	}
}

static void wipe_shadow_table(struct dm_transaction_manager *tm)
{
	struct shadow_info *si;
	struct hlist_node *n, *tmp;
	struct hlist_head *bucket;
	int i;

	spin_lock(&tm->lock);
	for (i = 0; i < HASH_SIZE; i++) {
		bucket = tm->buckets + i;
		hlist_for_each_entry_safe(si, n, tmp, bucket, hlist)
			kfree(si);

		INIT_HLIST_HEAD(bucket);
	}

	spin_unlock(&tm->lock);
}

/*----------------------------------------------------------------*/

static struct dm_transaction_manager *dm_tm_create(struct dm_block_manager *bm,
						   struct dm_space_map *sm)
{
	int i;
	struct dm_transaction_manager *tm;

	tm = kmalloc(sizeof(*tm), GFP_KERNEL);
	if (!tm)
		return ERR_PTR(-ENOMEM);

	tm->is_clone = 0;
	tm->real = NULL;
	tm->bm = bm;
	tm->sm = sm;

	spin_lock_init(&tm->lock);
	for (i = 0; i < HASH_SIZE; i++)
		INIT_HLIST_HEAD(tm->buckets + i);

	return tm;
}

struct dm_transaction_manager *dm_tm_create_non_blocking_clone(struct dm_transaction_manager *real)
{
	struct dm_transaction_manager *tm;

	tm = kmalloc(sizeof(*tm), GFP_KERNEL);
	if (tm) {
		tm->is_clone = 1;
		tm->real = real;
	}

	return tm;
}
EXPORT_SYMBOL_GPL(dm_tm_create_non_blocking_clone);

void dm_tm_destroy(struct dm_transaction_manager *tm)
{
	if (!tm->is_clone)
		wipe_shadow_table(tm);

	kfree(tm);
}
EXPORT_SYMBOL_GPL(dm_tm_destroy);

int dm_tm_pre_commit(struct dm_transaction_manager *tm)
{
	int r;

	if (tm->is_clone)
		return -EWOULDBLOCK;

	r = dm_sm_commit(tm->sm);
	if (r < 0)
		return r;

	return 0;
}
EXPORT_SYMBOL_GPL(dm_tm_pre_commit);

int dm_tm_commit(struct dm_transaction_manager *tm, struct dm_block *root)
{
	if (tm->is_clone)
		return -EWOULDBLOCK;

	wipe_shadow_table(tm);

	return dm_bm_flush_and_unlock(tm->bm, root);
}
EXPORT_SYMBOL_GPL(dm_tm_commit);

int dm_tm_new_block(struct dm_transaction_manager *tm,
		    struct dm_block_validator *v,
		    struct dm_block **result)
{
	int r;
	dm_block_t new_block;

	if (tm->is_clone)
		return -EWOULDBLOCK;

	r = dm_sm_new_block(tm->sm, &new_block);
	if (r < 0)
		return r;

	r = dm_bm_write_lock_zero(tm->bm, new_block, v, result);
	if (r < 0) {
		dm_sm_dec_block(tm->sm, new_block);
		return r;
	}

	/*
	 * New blocks count as shadows in that they don't need to be
	 * shadowed again.
	 */
	insert_shadow(tm, new_block);

	return 0;
}

static int __shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
			  struct dm_block_validator *v,
			  struct dm_block **result)
{
	int r;
	dm_block_t new;
	struct dm_block *orig_block;

	r = dm_sm_new_block(tm->sm, &new);
	if (r < 0)
		return r;

	r = dm_sm_dec_block(tm->sm, orig);
	if (r < 0)
		return r;

	r = dm_bm_read_lock(tm->bm, orig, v, &orig_block);
	if (r < 0)
		return r;

	/*
	 * It would be tempting to use dm_bm_unlock_move here, but some
	 * code, such as the space maps, keeps using the old data structures
	 * secure in the knowledge they won't be changed until the next
	 * transaction.  Using unlock_move would force a synchronous read
	 * since the old block would no longer be in the cache.
	 */
	r = dm_bm_write_lock_zero(tm->bm, new, v, result);
	if (r) {
		dm_bm_unlock(orig_block);
		return r;
	}

	memcpy(dm_block_data(*result), dm_block_data(orig_block),
	       dm_bm_block_size(tm->bm));

	dm_bm_unlock(orig_block);
	return r;
}

int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
		       struct dm_block_validator *v, struct dm_block **result,
		       int *inc_children)
{
	int r;

	if (tm->is_clone)
		return -EWOULDBLOCK;

	r = dm_sm_count_is_more_than_one(tm->sm, orig, inc_children);
	if (r < 0)
		return r;

	if (is_shadow(tm, orig) && !*inc_children)
		return dm_bm_write_lock(tm->bm, orig, v, result);

	r = __shadow_block(tm, orig, v, result);
	if (r < 0)
		return r;
	insert_shadow(tm, dm_block_location(*result));

	return r;
}
EXPORT_SYMBOL_GPL(dm_tm_shadow_block);

int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b,
		    struct dm_block_validator *v,
		    struct dm_block **blk)
{
	if (tm->is_clone)
		return dm_bm_read_try_lock(tm->real->bm, b, v, blk);

	return dm_bm_read_lock(tm->bm, b, v, blk);
}
EXPORT_SYMBOL_GPL(dm_tm_read_lock);

int dm_tm_unlock(struct dm_transaction_manager *tm, struct dm_block *b)
{
	return dm_bm_unlock(b);
}
EXPORT_SYMBOL_GPL(dm_tm_unlock);

void dm_tm_inc(struct dm_transaction_manager *tm, dm_block_t b)
{
	/*
	 * The non-blocking clone doesn't support this.
	 */
	BUG_ON(tm->is_clone);

	dm_sm_inc_block(tm->sm, b);
}
EXPORT_SYMBOL_GPL(dm_tm_inc);

void dm_tm_dec(struct dm_transaction_manager *tm, dm_block_t b)
{
	/*
	 * The non-blocking clone doesn't support this.
	 */
	BUG_ON(tm->is_clone);

	dm_sm_dec_block(tm->sm, b);
}
EXPORT_SYMBOL_GPL(dm_tm_dec);

int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b,
	      uint32_t *result)
{
	if (tm->is_clone)
		return -EWOULDBLOCK;

	return dm_sm_get_count(tm->sm, b, result);
}

struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm)
{
	return tm->bm;
}

/*----------------------------------------------------------------*/

static int dm_tm_create_internal(struct dm_block_manager *bm,
				 dm_block_t sb_location,
				 struct dm_transaction_manager **tm,
				 struct dm_space_map **sm,
				 int create,
				 void *sm_root, size_t sm_len)
{
	int r;

	*sm = dm_sm_metadata_init();
	if (IS_ERR(*sm))
		return PTR_ERR(*sm);

	*tm = dm_tm_create(bm, *sm);
	if (IS_ERR(*tm)) {
		dm_sm_destroy(*sm);
		return PTR_ERR(*tm);
	}

	if (create) {
		r = dm_sm_metadata_create(*sm, *tm, dm_bm_nr_blocks(bm),
					  sb_location);
		if (r) {
			DMERR("couldn't create metadata space map");
			goto bad;
		}

	} else {
		r = dm_sm_metadata_open(*sm, *tm, sm_root, sm_len);
		if (r) {
			DMERR("couldn't open metadata space map");
			goto bad;
		}
	}

	return 0;

bad:
	dm_tm_destroy(*tm);
	dm_sm_destroy(*sm);
	return r;
}

int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
			 struct dm_transaction_manager **tm,
			 struct dm_space_map **sm)
{
	return dm_tm_create_internal(bm, sb_location, tm, sm, 1, NULL, 0);
}
EXPORT_SYMBOL_GPL(dm_tm_create_with_sm);

int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
		       void *sm_root, size_t root_len,
		       struct dm_transaction_manager **tm,
		       struct dm_space_map **sm)
{
	return dm_tm_create_internal(bm, sb_location, tm, sm, 0, sm_root, root_len);
}
EXPORT_SYMBOL_GPL(dm_tm_open_with_sm);

/*----------------------------------------------------------------*/