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                 close(device->fd);
  80         }
  81         return 0;
  82 }
  83
  84 static struct btrfs_root *open_ctree_broken(int fd, const char *device)
  85 {
  86         u32 sectorsize;
  87         u32 nodesize;
  88         u32 leafsize;
  89         u32 blocksize;
  90         u32 stripesize;
  91         u64 generation;
  92         struct btrfs_root *tree_root = malloc(sizeof(struct btrfs_root));
  93         struct btrfs_root *extent_root = malloc(sizeof(struct btrfs_root));
  94         struct btrfs_root *chunk_root = malloc(sizeof(struct btrfs_root));
  95         struct btrfs_root *dev_root = malloc(sizeof(struct btrfs_root));
  96         struct btrfs_root *csum_root = malloc(sizeof(struct btrfs_root));
  97         struct btrfs_fs_info *fs_info = malloc(sizeof(*fs_info));
  98         int ret;
  99         struct btrfs_super_block *disk_super;
 100         struct btrfs_fs_devices *fs_devices = NULL;
 101         u64 total_devs;
 102         u64 features;
 103
 104         ret = btrfs_scan_one_device(fd, device, &fs_devices,
 105                                     &total_devs, BTRFS_SUPER_INFO_OFFSET);
 106
 107         if (ret) {
 108                 fprintf(stderr, "No valid Btrfs found on %s\n", device);
 109                 goto out;
 110         }
 111
 112         if (total_devs != 1) {
 113                 ret = btrfs_scan_for_fsid(fs_devices, total_devs, 1);
 114                 if (ret)
 115                         goto out;
 116         }
 117
 118         memset(fs_info, 0, sizeof(*fs_info));
 119         fs_info->tree_root = tree_root;
 120         fs_info->extent_root = extent_root;
 121         fs_info->chunk_root = chunk_root;
 122         fs_info->dev_root = dev_root;
 123         fs_info->csum_root = csum_root;
 124
 125         fs_info->readonly = 1;
 126
 127         extent_io_tree_init(&fs_info->extent_cache);
 128         extent_io_tree_init(&fs_info->free_space_cache);
 129         extent_io_tree_init(&fs_info->block_group_cache);
 130         extent_io_tree_init(&fs_info->pinned_extents);
 131         extent_io_tree_init(&fs_info->pending_del);
 132         extent_io_tree_init(&fs_info->extent_ins);
 133         cache_tree_init(&fs_info->fs_root_cache);
 134
 135         cache_tree_init(&fs_info->mapping_tree.cache_tree);
 136
 137         mutex_init(&fs_info->fs_mutex);
 138         fs_info->fs_devices = fs_devices;
 139         INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
 140         INIT_LIST_HEAD(&fs_info->space_info);
 141
 142         __setup_root(4096, 4096, 4096, 4096, tree_root,
 143                      fs_info, BTRFS_ROOT_TREE_OBJECTID);
 144
 145         ret = btrfs_open_devices(fs_devices, O_RDONLY);
 146         if (ret)
 147                 goto out_cleanup;
 148
 149         fs_info->super_bytenr = BTRFS_SUPER_INFO_OFFSET;
 150         disk_super = &fs_info->super_copy;
 151         ret = btrfs_read_dev_super(fs_devices->latest_bdev,
 152                                    disk_super, BTRFS_SUPER_INFO_OFFSET);
 153         if (ret) {
 154                 printk("No valid btrfs found\n");
 155                 goto out_devices;
 156         }
 157
 158         memcpy(fs_info->fsid, &disk_super->fsid, BTRFS_FSID_SIZE);
 159
 160
 161         features = btrfs_super_incompat_flags(disk_super) &
 162                    ~BTRFS_FEATURE_INCOMPAT_SUPP;
 163         if (features) {
 164                 printk("couldn't open because of unsupported "
 165                        "option features (%Lx).\n", features);
 166                 goto out_devices;
 167         }
 168
 169         features = btrfs_super_incompat_flags(disk_super);
 170         if (!(features & BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF)) {
 171                 features |= BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF;
 172                 btrfs_set_super_incompat_flags(disk_super, features);
 173         }
 174
 175         nodesize = btrfs_super_nodesize(disk_super);
 176         leafsize = btrfs_super_leafsize(disk_super);
 177         sectorsize = btrfs_super_sectorsize(disk_super);
 178         stripesize = btrfs_super_stripesize(disk_super);
 179         tree_root->nodesize = nodesize;
 180         tree_root->leafsize = leafsize;
 181         tree_root->sectorsize = sectorsize;
 182         tree_root->stripesize = stripesize;
 183
 184         ret = btrfs_read_sys_array(tree_root);
 185         if (ret)
 186                 goto out_devices;
 187         blocksize = btrfs_level_size(tree_root,
 188                                      btrfs_super_chunk_root_level(disk_super));
 189         generation = btrfs_super_chunk_root_generation(disk_super);
 190
 191         __setup_root(nodesize, leafsize, sectorsize, stripesize,
 192                      chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
 193
 194         chunk_root->node = read_tree_block(chunk_root,
 195                                            btrfs_super_chunk_root(disk_super),
 196                                            blocksize, generation);
 197         if (!chunk_root->node) {
 198                 printk("Couldn't read chunk root\n");
 199                 goto out_devices;
 200         }
 201
 202         read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
 203                  (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
 204                  BTRFS_UUID_SIZE);
 205
 206         if (!(btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)) {
 207                 ret = btrfs_read_chunk_tree(chunk_root);
 208                 if (ret)
 209                         goto out_chunk;
 210         }
 211
 212         return fs_info->chunk_root;
 213 out_chunk:
 214         free_extent_buffer(fs_info->chunk_root->node);
 215 out_devices:
 216         close_all_devices(fs_info);
 217 out_cleanup:
 218         extent_io_tree_cleanup(&fs_info->extent_cache);
 219         extent_io_tree_cleanup(&fs_info->free_space_cache);
 220         extent_io_tree_cleanup(&fs_info->block_group_cache);
 221         extent_io_tree_cleanup(&fs_info->pinned_extents);
 222         extent_io_tree_cleanup(&fs_info->pending_del);
 223         extent_io_tree_cleanup(&fs_info->extent_ins);
 224 out:
 225         free(tree_root);
 226         free(extent_root);
 227         free(chunk_root);
 228         free(dev_root);
 229         free(csum_root);
 230         free(fs_info);
 231         return NULL;
 232 }
 233
 234 static int search_iobuf(struct btrfs_root *root, void *iobuf,
 235                         size_t iobuf_size, off_t offset)
 236 {
 237         u64 gen = btrfs_super_generation(&root->fs_info->super_copy);
 238         u64 objectid = search_objectid;
 239         u32 size = btrfs_super_nodesize(&root->fs_info->super_copy);
 240         u8 level = root->fs_info->super_copy.root_level;
 241         size_t block_off = 0;
 242
 243         while (block_off < iobuf_size) {
 244                 void *block = iobuf + block_off;
 245                 struct btrfs_header *header = block;
 246                 u64 h_byte, h_level, h_gen, h_owner;
 247
 248 //              printf("searching %Lu\n", offset + block_off);
 249                 h_byte = le64_to_cpu(header->bytenr);
 250                 h_owner = le64_to_cpu(header->owner);
 251                 h_level = header->level;
 252                 h_gen = le64_to_cpu(header->generation);
 253
 254                 if (h_owner != objectid)
 255                         goto next;
 256                 if (h_byte != (offset + block_off))
 257                         goto next;
 258                 if (h_level != level)
 259                         goto next;
 260                 if (csum_block(block, size)) {
 261                         fprintf(stderr, "Well block %Lu seems good, "
 262                                 "but the csum doesn't match\n",
 263                                 h_byte);
 264                         goto next;
 265                 }
 266                 if (h_gen != gen) {
 267                         fprintf(stderr, "Well block %Lu seems great, "
 268                                 "but generation doesn't match, "
 269                                 "have=%Lu, want=%Lu\n", h_byte, h_gen,
 270                                 gen);
 271                         goto next;
 272                 }
 273                 printf("Found tree root at %Lu\n", h_byte);
 274                 return 0;
 275 next:
 276                 block_off += size;
 277         }
 278
 279         return 1;
 280 }
 281
 282 static int read_physical(struct btrfs_root *root, int fd, u64 offset,
 283                          u64 bytenr, u64 len)
 284 {
 285         char *iobuf = malloc(len);
 286         ssize_t done;
 287         size_t total_read = 0;
 288         int ret = 1;
 289
 290         if (!iobuf) {
 291                 fprintf(stderr, "No memory\n");
 292                 return -1;
 293         }
 294
 295         while (total_read < len) {
 296                 done = pread64(fd, iobuf + total_read, len - total_read,
 297                                bytenr + total_read);
 298                 if (done < 0) {
 299                         fprintf(stderr, "Failed to read: %s\n",
 300                                 strerror(errno));
 301                         ret = -1;
 302                         goto out;
 303                 }
 304                 total_read += done;
 305         }
 306
 307         ret = search_iobuf(root, iobuf, total_read, offset);
 308 out:
 309         free(iobuf);
 310         return ret;
 311 }
 312
 313 static int find_root(struct btrfs_root *root)
 314 {
 315         struct btrfs_multi_bio *multi = NULL;
 316         struct btrfs_device *device;
 317         u64 metadata_offset = 0, metadata_size = 0;
 318         off_t offset = 0;
 319         off_t bytenr;
 320         int fd;
 321         int err;
 322         int ret = 1;
 323
 324         printf("Super think's the tree root is at %Lu, chunk root %Lu\n",
 325                btrfs_super_root(&root->fs_info->super_copy),
 326                btrfs_super_chunk_root(&root->fs_info->super_copy));
 327
 328         err = btrfs_next_metadata(&root->fs_info->mapping_tree,
 329                                   &metadata_offset, &metadata_size);
 330         if (err)
 331                 return ret;
 332
 333         offset = metadata_offset;
 334         while (1) {
 335                 u64 map_length = 4096;
 336                 u64 type;
 337
 338                 if (offset >
 339                     btrfs_super_total_bytes(&root->fs_info->super_copy)) {
 340                         printf("Went past the fs size, exiting");
 341                         break;
 342                 }
 343                 if (offset >= (metadata_offset + metadata_size)) {
 344                         err = btrfs_next_metadata(&root->fs_info->mapping_tree,
 345                                                   &metadata_offset,
 346                                                   &metadata_size);
 347                         if (err) {
 348                                 printf("No more metdata to scan, exiting\n");
 349                                 break;
 350                         }
 351                         offset = metadata_offset;
 352                 }
 353                 err = __btrfs_map_block(&root->fs_info->mapping_tree, READ,
 354                                       offset, &map_length, &type,
 355                                       &multi, 0, NULL);
 356                 if (err) {
 357                         offset += map_length;
 358                         continue;
 359                 }
 360
 361                 if (!(type & BTRFS_BLOCK_GROUP_METADATA)) {
 362                         offset += map_length;
 363                         kfree(multi);
 364                         continue;
 365                 }
 366
 367                 device = multi->stripes[0].dev;
 368                 fd = device->fd;
 369                 bytenr = multi->stripes[0].physical;
 370                 kfree(multi);
 371
 372                 err = read_physical(root, fd, offset, bytenr, map_length);
 373                 if (!err) {
 374                         ret = 0;
 375                         break;
 376                 } else if (err < 0) {
 377                         ret = err;
 378                         break;
 379                 }
 380                 offset += map_length;
 381         }
 382         return ret;
 383 }
 384
 385 int main(int argc, char **argv)
 386 {
 387         struct btrfs_root *root;
 388         int dev_fd;
 389         int opt;
 390         int ret;
 391
 392         while ((opt = getopt(argc, argv, "o:")) != -1) {
 393                 switch(opt) {
 394                         case 'o':
 395                                 errno = 0;
 396                                 search_objectid = (u64)strtoll(optarg, NULL,
 397                                                                10);
 398                                 if (errno) {
 399                                         fprintf(stderr, "Error parsing "
 400                                                 "objectid\n");
 401                                         exit(1);
 402                                 }
 403                                 break;
 404                         default:
 405                                 usage();
 406                                 exit(1);
 407                 }
 408         }
 409
 410         if (optind >= argc) {
 411                 usage();
 412                 exit(1);
 413         }
 414
 415         dev_fd = open(argv[optind], O_RDONLY);
 416         if (dev_fd < 0) {
 417                 fprintf(stderr, "Failed to open device %s\n", argv[optind]);
 418                 exit(1);
 419         }
 420
 421         root = open_ctree_broken(dev_fd, argv[optind]);
 422         close(dev_fd);
 423
 424         if (!root) {
 425                 fprintf(stderr, "Open ctree failed\n");
 426                 exit(1);
 427         }
 428
 429         csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
 430         ret = find_root(root);
 431         close_ctree(root);
 432         return ret;
 433 }