summaryrefslogtreecommitdiff
path: root/btrfs-find-root.c
blob: 3e1396d3f4406123ebe31712a510907e93ea9ee6 (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
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
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
/*
 * Copyright (C) 2011 Red Hat.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 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.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#define _XOPEN_SOURCE 500
#define _GNU_SOURCE 1
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <zlib.h>
#include "kerncompat.h"
#include "ctree.h"
#include "disk-io.h"
#include "print-tree.h"
#include "transaction.h"
#include "list.h"
#include "version.h"
#include "volumes.h"
#include "utils.h"
#include "crc32c.h"

static u16 csum_size = 0;
static u64 search_objectid = BTRFS_ROOT_TREE_OBJECTID;

static void usage()
{
	fprintf(stderr, "Usage: find-roots [-o search_objectid] <device>\n");
}

int csum_block(void *buf, u32 len)
{
	char *result;
	u32 crc = ~(u32)0;
	int ret = 0;

	result = malloc(csum_size * sizeof(char));
	if (!result) {
		fprintf(stderr, "No memory\n");
		return 1;
	}

	len -= BTRFS_CSUM_SIZE;
	crc = crc32c(crc, buf + BTRFS_CSUM_SIZE, len);
	btrfs_csum_final(crc, result);

	if (memcmp(buf, result, csum_size))
		ret = 1;
	free(result);
	return ret;
}

static int close_all_devices(struct btrfs_fs_info *fs_info)
{
	struct list_head *list;
	struct list_head *next;
	struct btrfs_device *device;

	return 0;

	list = &fs_info->fs_devices->devices;
	list_for_each(next, list) {
		device = list_entry(next, struct btrfs_device, dev_list);
		if (device->fd != -1) {
			close(device->fd);
			device->fd = -1;
		}
	}
	return 0;
}

static struct btrfs_root *open_ctree_broken(int fd, const char *device)
{
	u32 sectorsize;
	u32 nodesize;
	u32 leafsize;
	u32 blocksize;
	u32 stripesize;
	u64 generation;
	struct btrfs_root *tree_root = malloc(sizeof(struct btrfs_root));
	struct btrfs_root *extent_root = malloc(sizeof(struct btrfs_root));
	struct btrfs_root *chunk_root = malloc(sizeof(struct btrfs_root));
	struct btrfs_root *dev_root = malloc(sizeof(struct btrfs_root));
	struct btrfs_root *csum_root = malloc(sizeof(struct btrfs_root));
	struct btrfs_fs_info *fs_info = malloc(sizeof(*fs_info));
	int ret;
	struct btrfs_super_block *disk_super;
	struct btrfs_fs_devices *fs_devices = NULL;
	u64 total_devs;
	u64 features;

	ret = btrfs_scan_one_device(fd, device, &fs_devices,
				    &total_devs, BTRFS_SUPER_INFO_OFFSET);

	if (ret) {
		fprintf(stderr, "No valid Btrfs found on %s\n", device);
		goto out;
	}

	if (total_devs != 1) {
		ret = btrfs_scan_for_fsid(fs_devices, total_devs, 1);
		if (ret)
			goto out;
	}

	memset(fs_info, 0, sizeof(*fs_info));
	fs_info->super_copy = calloc(1, BTRFS_SUPER_INFO_SIZE);
	fs_info->tree_root = tree_root;
	fs_info->extent_root = extent_root;
	fs_info->chunk_root = chunk_root;
	fs_info->dev_root = dev_root;
	fs_info->csum_root = csum_root;

	fs_info->readonly = 1;

	extent_io_tree_init(&fs_info->extent_cache);
	extent_io_tree_init(&fs_info->free_space_cache);
	extent_io_tree_init(&fs_info->block_group_cache);
	extent_io_tree_init(&fs_info->pinned_extents);
	extent_io_tree_init(&fs_info->pending_del);
	extent_io_tree_init(&fs_info->extent_ins);
	cache_tree_init(&fs_info->fs_root_cache);

	cache_tree_init(&fs_info->mapping_tree.cache_tree);

	mutex_init(&fs_info->fs_mutex);
	fs_info->fs_devices = fs_devices;
	INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
	INIT_LIST_HEAD(&fs_info->space_info);

	__setup_root(4096, 4096, 4096, 4096, tree_root,
		     fs_info, BTRFS_ROOT_TREE_OBJECTID);

	ret = btrfs_open_devices(fs_devices, O_RDONLY);
	if (ret)
		goto out_cleanup;

	fs_info->super_bytenr = BTRFS_SUPER_INFO_OFFSET;
	disk_super = fs_info->super_copy;
	ret = btrfs_read_dev_super(fs_devices->latest_bdev,
				   disk_super, BTRFS_SUPER_INFO_OFFSET);
	if (ret) {
		printk("No valid btrfs found\n");
		goto out_devices;
	}

	memcpy(fs_info->fsid, &disk_super->fsid, BTRFS_FSID_SIZE);


	features = btrfs_super_incompat_flags(disk_super) &
		   ~BTRFS_FEATURE_INCOMPAT_SUPP;
	if (features) {
		printk("couldn't open because of unsupported "
		       "option features (%Lx).\n", features);
		goto out_devices;
	}

	features = btrfs_super_incompat_flags(disk_super);
	if (!(features & BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF)) {
		features |= BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF;
		btrfs_set_super_incompat_flags(disk_super, features);
	}

	nodesize = btrfs_super_nodesize(disk_super);
	leafsize = btrfs_super_leafsize(disk_super);
	sectorsize = btrfs_super_sectorsize(disk_super);
	stripesize = btrfs_super_stripesize(disk_super);
	tree_root->nodesize = nodesize;
	tree_root->leafsize = leafsize;
	tree_root->sectorsize = sectorsize;
	tree_root->stripesize = stripesize;

	ret = btrfs_read_sys_array(tree_root);
	if (ret)
		goto out_devices;
	blocksize = btrfs_level_size(tree_root,
				     btrfs_super_chunk_root_level(disk_super));
	generation = btrfs_super_chunk_root_generation(disk_super);

	__setup_root(nodesize, leafsize, sectorsize, stripesize,
		     chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);

	chunk_root->node = read_tree_block(chunk_root,
					   btrfs_super_chunk_root(disk_super),
					   blocksize, generation);
	if (!chunk_root->node) {
		printk("Couldn't read chunk root\n");
		goto out_devices;
	}

	read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
	         (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
		 BTRFS_UUID_SIZE);

	if (!(btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)) {
		ret = btrfs_read_chunk_tree(chunk_root);
		if (ret)
			goto out_chunk;
	}

	return fs_info->chunk_root;
out_chunk:
	free_extent_buffer(fs_info->chunk_root->node);
out_devices:
	close_all_devices(fs_info);
out_cleanup:
	extent_io_tree_cleanup(&fs_info->extent_cache);
	extent_io_tree_cleanup(&fs_info->free_space_cache);
	extent_io_tree_cleanup(&fs_info->block_group_cache);
	extent_io_tree_cleanup(&fs_info->pinned_extents);
	extent_io_tree_cleanup(&fs_info->pending_del);
	extent_io_tree_cleanup(&fs_info->extent_ins);
out:
	free(tree_root);
	free(extent_root);
	free(chunk_root);
	free(dev_root);
	free(csum_root);
	free(fs_info);
	return NULL;
}

static int search_iobuf(struct btrfs_root *root, void *iobuf,
			size_t iobuf_size, off_t offset)
{
	u64 gen = btrfs_super_generation(root->fs_info->super_copy);
	u64 objectid = search_objectid;
	u32 size = btrfs_super_nodesize(root->fs_info->super_copy);
	u8 level = root->fs_info->super_copy->root_level;
	size_t block_off = 0;

	while (block_off < iobuf_size) {
		void *block = iobuf + block_off;
		struct btrfs_header *header = block;
		u64 h_byte, h_level, h_gen, h_owner;

//		printf("searching %Lu\n", offset + block_off);
		h_byte = le64_to_cpu(header->bytenr);
		h_owner = le64_to_cpu(header->owner);
		h_level = header->level;
		h_gen = le64_to_cpu(header->generation);

		if (h_owner != objectid)
			goto next;
		if (h_byte != (offset + block_off))
			goto next;
		if (h_level != level)
			goto next;
		if (csum_block(block, size)) {
			fprintf(stderr, "Well block %Lu seems good, "
				"but the csum doesn't match\n",
				h_byte);
			goto next;
		}
		if (h_gen != gen) {
			fprintf(stderr, "Well block %Lu seems great, "
				"but generation doesn't match, "
				"have=%Lu, want=%Lu\n", h_byte, h_gen,
				gen);
			goto next;
		}
		printf("Found tree root at %Lu\n", h_byte);
		return 0;
next:
		block_off += size;
	}

	return 1;
}

static int read_physical(struct btrfs_root *root, int fd, u64 offset,
			 u64 bytenr, u64 len)
{
	char *iobuf = malloc(len);
	ssize_t done;
	size_t total_read = 0;
	int ret = 1;

	if (!iobuf) {
		fprintf(stderr, "No memory\n");
		return -1;
	}

	while (total_read < len) {
		done = pread64(fd, iobuf + total_read, len - total_read,
			       bytenr + total_read);
		if (done < 0) {
			fprintf(stderr, "Failed to read: %s\n",
				strerror(errno));
			ret = -1;
			goto out;
		}
		total_read += done;
	}

	ret = search_iobuf(root, iobuf, total_read, offset);
out:
	free(iobuf);
	return ret;
}

static int find_root(struct btrfs_root *root)
{
	struct btrfs_multi_bio *multi = NULL;
	struct btrfs_device *device;
	u64 metadata_offset = 0, metadata_size = 0;
	off_t offset = 0;
	off_t bytenr;
	int fd;
	int err;
	int ret = 1;

	printf("Super think's the tree root is at %Lu, chunk root %Lu\n",
	       btrfs_super_root(root->fs_info->super_copy),
	       btrfs_super_chunk_root(root->fs_info->super_copy));

	err = btrfs_next_metadata(&root->fs_info->mapping_tree,
				  &metadata_offset, &metadata_size);
	if (err)
		return ret;

	offset = metadata_offset;
	while (1) {
		u64 map_length = 4096;
		u64 type;

		if (offset >
		    btrfs_super_total_bytes(root->fs_info->super_copy)) {
			printf("Went past the fs size, exiting");
			break;
		}
		if (offset >= (metadata_offset + metadata_size)) {
			err = btrfs_next_metadata(&root->fs_info->mapping_tree,
						  &metadata_offset,
						  &metadata_size);
			if (err) {
				printf("No more metdata to scan, exiting\n");
				break;
			}
			offset = metadata_offset;
		}
		err = __btrfs_map_block(&root->fs_info->mapping_tree, READ,
				      offset, &map_length, &type,
				      &multi, 0, NULL);
		if (err) {
			offset += map_length;
			continue;
		}

		if (!(type & BTRFS_BLOCK_GROUP_METADATA)) {
			offset += map_length;
			kfree(multi);
			continue;
		}

		device = multi->stripes[0].dev;
		fd = device->fd;
		bytenr = multi->stripes[0].physical;
		kfree(multi);

		err = read_physical(root, fd, offset, bytenr, map_length);
		if (!err) {
			ret = 0;
			break;
		} else if (err < 0) {
			ret = err;
			break;
		}
		offset += map_length;
	}
	return ret;
}

int main(int argc, char **argv)
{
	struct btrfs_root *root;
	int dev_fd;
	int opt;
	int ret;

	while ((opt = getopt(argc, argv, "o:")) != -1) {
		switch(opt) {
			case 'o':
				errno = 0;
				search_objectid = (u64)strtoll(optarg, NULL,
							       10);
				if (errno) {
					fprintf(stderr, "Error parsing "
						"objectid\n");
					exit(1);
				}
				break;
			default:
				usage();
				exit(1);
		}
	}

	if (optind >= argc) {
		usage();
		exit(1);
	}

	dev_fd = open(argv[optind], O_RDONLY);
	if (dev_fd < 0) {
		fprintf(stderr, "Failed to open device %s\n", argv[optind]);
		exit(1);
	}

	root = open_ctree_broken(dev_fd, argv[optind]);
	close(dev_fd);

	if (!root) {
		fprintf(stderr, "Open ctree failed\n");
		exit(1);
	}

	csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
	ret = find_root(root);
	close_ctree(root);
	return ret;
}