btrfs-find-root.c

   1 /*
   2  * Copyright (C) 2011 Red Hat.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #define _XOPEN_SOURCE 500
  20 #define _GNU_SOURCE 1
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <unistd.h>
  24 #include <fcntl.h>
  25 #include <sys/stat.h>
  26 #include <zlib.h>
  27 #include "kerncompat.h"
  28 #include "ctree.h"
  29 #include "disk-io.h"
  30 #include "print-tree.h"
  31 #include "transaction.h"
  32 #include "list.h"
  33 #include "version.h"
  34 #include "volumes.h"
  35 #include "utils.h"
  36 #include "crc32c.h"
  37
  38 static u16 csum_size = 0;
  39 static u64 search_objectid = BTRFS_ROOT_TREE_OBJECTID;
  40
  41 static void usage()
  42 {
  43         fprintf(stderr, "Usage: find-roots [-o search_objectid] <device>\n");
  44 }
  45
  46 int csum_block(void *buf, u32 len)
  47 {
  48         char *result;
  49         u32 crc = ~(u32)0;
  50         int ret = 0;
  51
  52         result = malloc(csum_size * sizeof(char));
  53         if (!result) {
  54                 fprintf(stderr, "No memory\n");
  55                 return 1;
  56         }
  57
  58         len -= BTRFS_CSUM_SIZE;
  59         crc = crc32c(crc, buf + BTRFS_CSUM_SIZE, len);
  60         btrfs_csum_final(crc, result);
  61
  62         if (memcmp(buf, result, csum_size))
  63                 ret = 1;
  64         free(result);
  65         return ret;
  66 }
  67
  68 static int close_all_devices(struct btrfs_fs_info *fs_info)
  69 {
  70         struct list_head *list;
  71         struct list_head *next;
  72         struct btrfs_device *device;
  73
  74         return 0;
  75
  76         list = &fs_info->fs_devices->devices;
  77         list_for_each(next, list) {
  78                 device = list_entry(next, struct btrfs_device, dev_list);
  79                 if (device->fd != -1) {
  80                         close(device->fd);
  81                         device->fd = -1;
  82                 }
  83         }
  84         return 0;
  85 }
  86
  87 static struct btrfs_root *open_ctree_broken(int fd, const char *device)
  88 {
  89         u32 sectorsize;
  90         u32 nodesize;
  91         u32 leafsize;
  92         u32 blocksize;
  93         u32 stripesize;
  94         u64 generation;
  95         struct btrfs_root *tree_root = malloc(sizeof(struct btrfs_root));
  96         struct btrfs_root *extent_root = malloc(sizeof(struct btrfs_root));
  97         struct btrfs_root *chunk_root = malloc(sizeof(struct btrfs_root));
  98         struct btrfs_root *dev_root = malloc(sizeof(struct btrfs_root));
  99         struct btrfs_root *csum_root = malloc(sizeof(struct btrfs_root));
 100         struct btrfs_fs_info *fs_info = malloc(sizeof(*fs_info));
 101         int ret;
 102         struct btrfs_super_block *disk_super;
 103         struct btrfs_fs_devices *fs_devices = NULL;
 104         u64 total_devs;
 105         u64 features;
 106
 107         ret = btrfs_scan_one_device(fd, device, &fs_devices,
 108                                     &total_devs, BTRFS_SUPER_INFO_OFFSET);
 109
 110         if (ret) {
 111                 fprintf(stderr, "No valid Btrfs found on %s\n", device);
 112                 goto out;
 113         }
 114
 115         if (total_devs != 1) {
 116                 ret = btrfs_scan_for_fsid(fs_devices, total_devs, 1);
 117                 if (ret)
 118                         goto out;
 119         }
 120
 121         memset(fs_info, 0, sizeof(*fs_info));
 122         fs_info->super_copy = calloc(1, BTRFS_SUPER_INFO_SIZE);
 123         fs_info->tree_root = tree_root;
 124         fs_info->extent_root = extent_root;
 125         fs_info->chunk_root = chunk_root;
 126         fs_info->dev_root = dev_root;
 127         fs_info->csum_root = csum_root;
 128
 129         fs_info->readonly = 1;
 130
 131         extent_io_tree_init(&fs_info->extent_cache);
 132         extent_io_tree_init(&fs_info->free_space_cache);
 133         extent_io_tree_init(&fs_info->block_group_cache);
 134         extent_io_tree_init(&fs_info->pinned_extents);
 135         extent_io_tree_init(&fs_info->pending_del);
 136         extent_io_tree_init(&fs_info->extent_ins);
 137         cache_tree_init(&fs_info->fs_root_cache);
 138
 139         cache_tree_init(&fs_info->mapping_tree.cache_tree);
 140
 141         mutex_init(&fs_info->fs_mutex);
 142         fs_info->fs_devices = fs_devices;
 143         INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
 144         INIT_LIST_HEAD(&fs_info->space_info);
 145
 146         __setup_root(4096, 4096, 4096, 4096, tree_root,
 147                      fs_info, BTRFS_ROOT_TREE_OBJECTID);
 148
 149         ret = btrfs_open_devices(fs_devices, O_RDONLY);
 150         if (ret)
 151                 goto out_cleanup;
 152
 153         fs_info->super_bytenr = BTRFS_SUPER_INFO_OFFSET;
 154         disk_super = fs_info->super_copy;
 155         ret = btrfs_read_dev_super(fs_devices->latest_bdev,
 156                                    disk_super, BTRFS_SUPER_INFO_OFFSET);
 157         if (ret) {
 158                 printk("No valid btrfs found\n");
 159                 goto out_devices;
 160         }
 161
 162         memcpy(fs_info->fsid, &disk_super->fsid, BTRFS_FSID_SIZE);
 163
 164
 165         features = btrfs_super_incompat_flags(disk_super) &
 166                    ~BTRFS_FEATURE_INCOMPAT_SUPP;
 167         if (features) {
 168                 printk("couldn't open because of unsupported "
 169                        "option features (%Lx).\n", features);
 170                 goto out_devices;
 171         }
 172
 173         features = btrfs_super_incompat_flags(disk_super);
 174         if (!(features & BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF)) {
 175                 features |= BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF;
 176                 btrfs_set_super_incompat_flags(disk_super, features);
 177         }
 178
 179         nodesize = btrfs_super_nodesize(disk_super);
 180         leafsize = btrfs_super_leafsize(disk_super);
 181         sectorsize = btrfs_super_sectorsize(disk_super);
 182         stripesize = btrfs_super_stripesize(disk_super);
 183         tree_root->nodesize = nodesize;
 184         tree_root->leafsize = leafsize;
 185         tree_root->sectorsize = sectorsize;
 186         tree_root->stripesize = stripesize;
 187
 188         ret = btrfs_read_sys_array(tree_root);
 189         if (ret)
 190                 goto out_devices;
 191         blocksize = btrfs_level_size(tree_root,
 192                                      btrfs_super_chunk_root_level(disk_super));
 193         generation = btrfs_super_chunk_root_generation(disk_super);
 194
 195         __setup_root(nodesize, leafsize, sectorsize, stripesize,
 196                      chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
 197
 198         chunk_root->node = read_tree_block(chunk_root,
 199                                            btrfs_super_chunk_root(disk_super),
 200                                            blocksize, generation);
 201         if (!chunk_root->node) {
 202                 printk("Couldn't read chunk root\n");
 203                 goto out_devices;
 204         }
 205
 206         read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
 207                  (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
 208                  BTRFS_UUID_SIZE);
 209
 210         if (!(btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)) {
 211                 ret = btrfs_read_chunk_tree(chunk_root);
 212                 if (ret)
 213                         goto out_chunk;
 214         }
 215
 216         return fs_info->chunk_root;
 217 out_chunk:
 218         free_extent_buffer(fs_info->chunk_root->node);
 219 out_devices:
 220         close_all_devices(fs_info);
 221 out_cleanup:
 222         extent_io_tree_cleanup(&fs_info->extent_cache);
 223         extent_io_tree_cleanup(&fs_info->free_space_cache);
 224         extent_io_tree_cleanup(&fs_info->block_group_cache);
 225         extent_io_tree_cleanup(&fs_info->pinned_extents);
 226         extent_io_tree_cleanup(&fs_info->pending_del);
 227         extent_io_tree_cleanup(&fs_info->extent_ins);
 228 out:
 229         free(tree_root);
 230         free(extent_root);
 231         free(chunk_root);
 232         free(dev_root);
 233         free(csum_root);
 234         free(fs_info);
 235         return NULL;
 236 }
 237
 238 static int search_iobuf(struct btrfs_root *root, void *iobuf,
 239                         size_t iobuf_size, off_t offset)
 240 {
 241         u64 gen = btrfs_super_generation(root->fs_info->super_copy);
 242         u64 objectid = search_objectid;
 243         u32 size = btrfs_super_nodesize(root->fs_info->super_copy);
 244         u8 level = root->fs_info->super_copy->root_level;
 245         size_t block_off = 0;
 246
 247         while (block_off < iobuf_size) {
 248                 void *block = iobuf + block_off;
 249                 struct btrfs_header *header = block;
 250                 u64 h_byte, h_level, h_gen, h_owner;
 251
 252 //              printf("searching %Lu\n", offset + block_off);
 253                 h_byte = le64_to_cpu(header->bytenr);
 254                 h_owner = le64_to_cpu(header->owner);
 255                 h_level = header->level;
 256                 h_gen = le64_to_cpu(header->generation);
 257
 258                 if (h_owner != objectid)
 259                         goto next;
 260                 if (h_byte != (offset + block_off))
 261                         goto next;
 262                 if (h_level != level)
 263                         goto next;
 264                 if (csum_block(block, size)) {
 265                         fprintf(stderr, "Well block %Lu seems good, "
 266                                 "but the csum doesn't match\n",
 267                                 h_byte);
 268                         goto next;
 269                 }
 270                 if (h_gen != gen) {
 271                         fprintf(stderr, "Well block %Lu seems great, "
 272                                 "but generation doesn't match, "
 273                                 "have=%Lu, want=%Lu\n", h_byte, h_gen,
 274                                 gen);
 275                         goto next;
 276                 }
 277                 printf("Found tree root at %Lu\n", h_byte);
 278                 return 0;
 279 next:
 280                 block_off += size;
 281         }
 282
 283         return 1;
 284 }
 285
 286 static int read_physical(struct btrfs_root *root, int fd, u64 offset,
 287                          u64 bytenr, u64 len)
 288 {
 289         char *iobuf = malloc(len);
 290         ssize_t done;
 291         size_t total_read = 0;
 292         int ret = 1;
 293
 294         if (!iobuf) {
 295                 fprintf(stderr, "No memory\n");
 296                 return -1;
 297         }
 298
 299         while (total_read < len) {
 300                 done = pread64(fd, iobuf + total_read, len - total_read,
 301                                bytenr + total_read);
 302                 if (done < 0) {
 303                         fprintf(stderr, "Failed to read: %s\n",
 304                                 strerror(errno));
 305                         ret = -1;
 306                         goto out;
 307                 }
 308                 total_read += done;
 309         }
 310
 311         ret = search_iobuf(root, iobuf, total_read, offset);
 312 out:
 313         free(iobuf);
 314         return ret;
 315 }
 316
 317 static int find_root(struct btrfs_root *root)
 318 {
 319         struct btrfs_multi_bio *multi = NULL;
 320         struct btrfs_device *device;
 321         u64 metadata_offset = 0, metadata_size = 0;
 322         off_t offset = 0;
 323         off_t bytenr;
 324         int fd;
 325         int err;
 326         int ret = 1;
 327
 328         printf("Super think's the tree root is at %Lu, chunk root %Lu\n",
 329                btrfs_super_root(root->fs_info->super_copy),
 330                btrfs_super_chunk_root(root->fs_info->super_copy));
 331
 332         err = btrfs_next_metadata(&root->fs_info->mapping_tree,
 333                                   &metadata_offset, &metadata_size);
 334         if (err)
 335                 return ret;
 336
 337         offset = metadata_offset;
 338         while (1) {
 339                 u64 map_length = 4096;
 340                 u64 type;
 341
 342                 if (offset >
 343                     btrfs_super_total_bytes(root->fs_info->super_copy)) {
 344                         printf("Went past the fs size, exiting");
 345                         break;
 346                 }
 347                 if (offset >= (metadata_offset + metadata_size)) {
 348                         err = btrfs_next_metadata(&root->fs_info->mapping_tree,
 349                                                   &metadata_offset,
 350                                                   &metadata_size);
 351                         if (err) {
 352                                 printf("No more metdata to scan, exiting\n");
 353                                 break;
 354                         }
 355                         offset = metadata_offset;
 356                 }
 357                 err = __btrfs_map_block(&root->fs_info->mapping_tree, READ,
 358                                       offset, &map_length, &type,
 359                                       &multi, 0, NULL);
 360                 if (err) {
 361                         offset += map_length;
 362                         continue;
 363                 }
 364
 365                 if (!(type & BTRFS_BLOCK_GROUP_METADATA)) {
 366                         offset += map_length;
 367                         kfree(multi);
 368                         continue;
 369                 }
 370
 371                 device = multi->stripes[0].dev;
 372                 fd = device->fd;
 373                 bytenr = multi->stripes[0].physical;
 374                 kfree(multi);
 375
 376                 err = read_physical(root, fd, offset, bytenr, map_length);
 377                 if (!err) {
 378                         ret = 0;
 379                         break;
 380                 } else if (err < 0) {
 381                         ret = err;
 382                         break;
 383                 }
 384                 offset += map_length;
 385         }
 386         return ret;
 387 }
 388
 389 int main(int argc, char **argv)
 390 {
 391         struct btrfs_root *root;
 392         int dev_fd;
 393         int opt;
 394         int ret;
 395
 396         while ((opt = getopt(argc, argv, "o:")) != -1) {
 397                 switch(opt) {
 398                         case 'o':
 399                                 errno = 0;
 400                                 search_objectid = (u64)strtoll(optarg, NULL,
 401                                                                10);
 402                                 if (errno) {
 403                                         fprintf(stderr, "Error parsing "
 404                                                 "objectid\n");
 405                                         exit(1);
 406                                 }
 407                                 break;
 408                         default:
 409                                 usage();
 410                                 exit(1);
 411                 }
 412         }
 413
 414         if (optind >= argc) {
 415                 usage();
 416                 exit(1);
 417         }
 418
 419         dev_fd = open(argv[optind], O_RDONLY);
 420         if (dev_fd < 0) {
 421                 fprintf(stderr, "Failed to open device %s\n", argv[optind]);
 422                 exit(1);
 423         }
 424
 425         root = open_ctree_broken(dev_fd, argv[optind]);
 426         close(dev_fd);
 427
 428         if (!root) {
 429                 fprintf(stderr, "Open ctree failed\n");
 430                 exit(1);
 431         }
 432
 433         csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 434         ret = find_root(root);
 435         close_ctree(root);
 436         return ret;
 437 }