summaryrefslogtreecommitdiffstats
path: root/src/barebox-state/backend_storage.c
blob: b7b6882d68b77cea18387954cb750a328ac41a49 (plain) (blame)
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
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
/*
 * Copyright (C) 2016 Pengutronix, Markus Pargmann <mpa@pengutronix.de>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <asm-generic/ioctl.h>
#include <fcntl.h>
#include <fs.h>
#include <libfile.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mtd/mtd-abi.h>
#include <linux/stat.h>
#include <linux/fs.h>
#include <malloc.h>
#include <printk.h>

#include "state.h"

/*
 * The state framework stores data in so called buckets. A bucket is
 * exactly one copy of the state we want to store. On flash type media
 * a bucket corresponds to a single eraseblock. On media which do not
 * need an erase operation a bucket corresponds to a storage area of
 * @stridesize bytes.
 *
 * For redundancy and to make sure that we have valid data on the storage
 * device at any time the state framework stores multiple buckets. The strategy
 * is as follows:
 *
 * When loading the state from the storage we iterate over the buckets. We
 * take the first one we find which has valid crcs. The next step is to
 * restore consistency between the different buckets. This means rewriting
 * a bucket when it signalled it needs refresh (i.e. returned -EUCLEAN)
 * or when contains data different from the bucket we use.
 *
 * When the state backend initialized successfully we already restored
 * consistency which means all buckets contain the same data. This means
 * when storing a new state we can just write all buckets in order.
 */

const unsigned int min_copies_written = 1;

/**
 * state_storage_write - Writes the given data to the storage
 * @param storage Storage object
 * @param buf Buffer with the data
 * @param len Length of the buffer
 * @return 0 on success, -errno otherwise
 *
 * This function iterates over all registered buckets and executes a write
 * operation on all of them. Writes are always in the same sequence. This
 * ensures, that reading in the same sequence will always return the latest
 * written valid data first.
 * We try to at least write min_copies_written. If this fails we return with an
 * error.
 */
int state_storage_write(struct state_backend_storage *storage,
		        const void * buf, ssize_t len)
{
	struct state_backend_storage_bucket *bucket;
	int ret;
	int copies_written = 0;

	if (storage->readonly)
		return 0;

	list_for_each_entry(bucket, &storage->buckets, bucket_list) {
		ret = bucket->write(bucket, buf, len);
		if (ret < 0) {
			dev_warn(storage->dev, "Failed to write state backend bucket, %d\n",
				 ret);
		} else {
			++copies_written;
		}
	}

	if (copies_written >= min_copies_written)
		return 0;

	dev_err(storage->dev, "Failed to write state to at least %d buckets. Successfully written to %d buckets\n",
		min_copies_written, copies_written);
	return -EIO;
}

static int bucket_refresh(struct state_backend_storage *storage,
			  struct state_backend_storage_bucket *bucket, void *buf, ssize_t len)
{
	int ret;

	if (bucket->needs_refresh)
		goto refresh;

	if (bucket->len != len)
		goto refresh;

	if (memcmp(bucket->buf, buf, len))
		goto refresh;

	return 0;

refresh:
	ret = bucket->write(bucket, buf, len);

	if (ret)
		dev_warn(storage->dev, "Failed to restore bucket %d@0x%08lx\n",
			 bucket->num, bucket->offset);
	else
		dev_info(storage->dev, "restored bucket %d@0x%08lx\n",
			 bucket->num, bucket->offset);

	return ret;
}

/**
 * state_storage_read - Reads valid data from the backend storage
 * @param storage Storage object
 * @param format Format of the data that is stored
 * @param magic state magic value
 * @param buf The newly allocated data area will be stored in this pointer
 * @param len The resulting length of the buffer
 * @return 0 on success, -errno otherwise. buf and len will be set to valid
 * values on success.
 *
 * This function goes through all buckets and tries to read valid data from
 * them. The first bucket which returns data that is successfully verified
 * against the data format is used. To ensure the validity of all bucket copies,
 * we restore the consistency at the end.
 */
int state_storage_read(struct state_backend_storage *storage,
		       struct state_backend_format *format,
		       uint32_t magic, void **buf, ssize_t *len)
{
	struct state_backend_storage_bucket *bucket, *bucket_used = NULL;
	int ret;

	/*
	 * Iterate over all buckets. The first valid one we find is the
	 * one we want to use.
	 */
	list_for_each_entry(bucket, &storage->buckets, bucket_list) {
		ret = bucket->read(bucket, &bucket->buf, &bucket->len);
		if (ret == -EUCLEAN)
			bucket->needs_refresh = 1;
		else if (ret)
			continue;

		/*
		 * Verify the buffer crcs. The buffer length is passed in the len argument,
		 * .verify overwrites it with the length actually used.
		 */
		ret = format->verify(format, magic, bucket->buf, &bucket->len);
		if (!ret && !bucket_used)
			bucket_used = bucket;
	}

	if (!bucket_used) {
		dev_err(storage->dev, "Failed to find any valid state copy in any bucket\n");

		return -ENOENT;
	}

	dev_info(storage->dev, "Using bucket %d@0x%08lx\n", bucket_used->num, bucket_used->offset);

	/*
	 * Restore/refresh all buckets except the one we currently use (in case
	 * it's the only usable bucket at the moment)
	 */
	list_for_each_entry(bucket, &storage->buckets, bucket_list) {
		if (bucket == bucket_used)
			continue;

		ret = bucket_refresh(storage, bucket, bucket_used->buf, bucket_used->len);

		/* Free buffer from the unused buckets */
		free(bucket->buf);
		bucket->buf = NULL;
	}

	/*
	 * Restore/refresh the bucket we currently use
	 */
	ret = bucket_refresh(storage, bucket_used, bucket_used->buf, bucket_used->len);

	*buf = bucket_used->buf;
	*len = bucket_used->len;

	/* buffer from the used bucket is passed to the caller, do not free */
	bucket_used->buf = NULL;

	return 0;
}

static int mtd_get_meminfo(const char *path, struct mtd_info_user *meminfo)
{
	int fd, ret;

	fd = open(path, O_RDONLY);
	if (fd < 0) {
		pr_err("Failed to open '%s', %d\n", path, ret);
		return fd;
	}

	ret = ioctl(fd, MEMGETINFO, meminfo);

	close(fd);

	return ret;
}

/* Number of copies that should be allocated */
const int desired_copies = 3;

/**
 * state_storage_mtd_buckets_init - Creates storage buckets for mtd devices
 * @param storage Storage object
 * @param meminfo Info about the mtd device
 * @param circular If false, use non-circular mode to write data that is compatible with the old on-flash format
 * @return 0 on success, -errno otherwise
 *
 * Starting from offset 0 this function tries to create circular buckets on
 * different offsets in the device. Different copies of the data are located in
 * different eraseblocks.
 * For MTD devices we use circular buckets to minimize the number of erases.
 * Circular buckets write new data always in the next free space.
 */
static int state_storage_mtd_buckets_init(struct state_backend_storage *storage,
					  struct mtd_info_user *meminfo, bool circular)
{
	struct state_backend_storage_bucket *bucket;
	ssize_t end = storage->offset + storage->max_size;
	int nr_copies = 0;
	off_t offset;
	ssize_t writesize;

	if (!end || end > meminfo->size)
		end = meminfo->size;

	if (!IS_ALIGNED(storage->offset, meminfo->erasesize)) {
		dev_err(storage->dev, "Offset within the device is not aligned to eraseblocks. Offset is %ld, erasesize %zu\n",
			storage->offset, meminfo->erasesize);
		return -EINVAL;
	}

	if (circular)
		writesize = meminfo->writesize;
	else
		writesize = meminfo->erasesize;

	for (offset = storage->offset; offset < end; offset += meminfo->erasesize) {
		int ret;
		unsigned int eraseblock = offset / meminfo->erasesize;

		ret = state_backend_bucket_circular_create(storage->dev, storage->path,
							   &bucket,
							   eraseblock,
							   writesize,
							   meminfo);
		if (ret)
			continue;

		bucket->offset = offset;
		bucket->num = nr_copies;

		list_add_tail(&bucket->bucket_list, &storage->buckets);
		++nr_copies;
		if (nr_copies >= desired_copies)
			return 0;
	}

	if (!nr_copies) {
		dev_err(storage->dev, "Failed to initialize any state storage bucket\n");
		return -EIO;
	}

	dev_warn(storage->dev, "Failed to initialize desired amount of buckets, only %d of %d succeeded\n",
		 nr_copies, desired_copies);
	return 0;
}

/**
 * state_storage_file_buckets_init - Create buckets for a conventional file descriptor
 * @param storage Storage object
 * @return 0 on success, -errno otherwise
 *
 * For blockdevices and other regular files we create direct buckets beginning
 * at offset 0. Direct buckets are simple and write data always to offset 0.
 */
static int state_storage_file_buckets_init(struct state_backend_storage *storage)
{
	struct state_backend_storage_bucket *bucket;
	int ret, n;
	off_t offset;
	int nr_copies = 0;
	uint32_t stridesize = storage->stridesize;
	size_t max_size = storage->max_size;

	if (!stridesize) {
		dev_err(storage->dev, "stridesize unspecified\n");
		return -EINVAL;
	}

	if (max_size && max_size < desired_copies * stridesize) {
		dev_err(storage->dev, "device is too small to hold %d copies\n", desired_copies);
		return -EINVAL;
	}

	for (n = 0; n < desired_copies; n++) {
		offset = storage->offset + n * stridesize;
		ret = state_backend_bucket_direct_create(storage->dev, storage->path,
							 &bucket, offset,
							 stridesize);
		if (ret) {
			dev_warn(storage->dev, "Failed to create direct bucket at '%s' offset %ld\n",
				 storage->path, offset);
			continue;
		}

		bucket->offset = offset;
		bucket->num = nr_copies;

		list_add_tail(&bucket->bucket_list, &storage->buckets);
		++nr_copies;
	}

	if (!nr_copies) {
		dev_err(storage->dev, "Failed to initialize any state direct storage bucket\n");
		return -EIO;
	}

	if (nr_copies < desired_copies)
		dev_warn(storage->dev, "Failed to initialize desired amount of direct buckets, only %d of %d succeeded\n",
			nr_copies, desired_copies);

	return 0;
}


/**
 * state_storage_init - Init backend storage
 * @param path Path to the backend storage file
 * @param dev_offset Offset in the device to start writing at.
 * @param max_size Maximum size of the data. May be 0 for infinite.
 * @param stridesize Distance between two copies of the data. Not relevant for MTD
 * @param storagetype Type of the storage backend. This may be NULL where we
 * autoselect some backwardscompatible backend options
 * @return 0 on success, -errno otherwise
 *
 * Depending on the filetype, we create mtd buckets or normal file buckets.
 */
int state_storage_init(struct state *state, const char *path,
		       off_t offset, size_t max_size, uint32_t stridesize,
		       const char *storagetype)
{
	struct state_backend_storage *storage = &state->storage;
	int ret;
	struct mtd_info_user meminfo;

	INIT_LIST_HEAD(&storage->buckets);
	storage->dev = &state->dev;
	storage->name = storagetype;
	storage->stridesize = stridesize;
	storage->offset = offset;
	storage->max_size = max_size;
	storage->path = xstrdup(path);

	ret = mtd_get_meminfo(path, &meminfo);
	if (!ret && !(meminfo.flags & MTD_NO_ERASE)) {
		bool circular;
		if (!storagetype || !strcmp(storagetype, "circular")) {
			circular = true;
		} else if (!strcmp(storagetype, "noncircular")) {
			dev_warn(storage->dev, "using old format circular storage type.\n");
			circular = false;
		} else {
			dev_warn(storage->dev, "unknown storage type '%s'\n", storagetype);
			return -EINVAL;
		}
		return state_storage_mtd_buckets_init(storage, &meminfo, circular);
	} else {
		return state_storage_file_buckets_init(storage);
	}

	dev_err(storage->dev, "storage init done\n");
}

void state_storage_set_readonly(struct state_backend_storage *storage)
{
	storage->readonly = true;
}

/**
 * state_storage_free - Free backend storage
 * @param storage Storage object
 */
void state_storage_free(struct state_backend_storage *storage)
{
	struct state_backend_storage_bucket *bucket;
	struct state_backend_storage_bucket *bucket_tmp;

	if (!storage->buckets.next)
		return;

	list_for_each_entry_safe(bucket, bucket_tmp, &storage->buckets,
				 bucket_list) {
		list_del(&bucket->bucket_list);
		bucket->free(bucket);
	}

	free(storage->path);
}