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 struct btrfs_root *open_ctree_broken(int fd, const char *device)
  69 {
  70         u32 sectorsize;
  71         u32 nodesize;
  72         u32 leafsize;
  73         u32 blocksize;
  74         u32 stripesize;
  75         u64 generation;
  76         struct btrfs_root *tree_root = malloc(sizeof(struct btrfs_root));
  77         struct btrfs_root *extent_root = malloc(sizeof(struct btrfs_root));
  78         struct btrfs_root *chunk_root = malloc(sizeof(struct btrfs_root));
  79         struct btrfs_root *dev_root = malloc(sizeof(struct btrfs_root));
  80         struct btrfs_root *csum_root = malloc(sizeof(struct btrfs_root));
  81         struct btrfs_fs_info *fs_info = malloc(sizeof(*fs_info));
  82         int ret;
  83         struct btrfs_super_block *disk_super;
  84         struct btrfs_fs_devices *fs_devices = NULL;
  85         u64 total_devs;
  86         u64 features;
  87
  88         ret = btrfs_scan_one_device(fd, device, &fs_devices,
  89                                     &total_devs, BTRFS_SUPER_INFO_OFFSET);
  90
  91         if (ret) {
  92                 fprintf(stderr, "No valid Btrfs found on %s\n", device);
  93                 goto out;
  94         }
  95
  96         if (total_devs != 1) {
  97                 ret = btrfs_scan_for_fsid(fs_devices, total_devs, 1);
  98                 if (ret)
  99                         goto out;
 100         }
 101
 102         memset(fs_info, 0, sizeof(*fs_info));
 103         fs_info->super_copy = calloc(1, BTRFS_SUPER_INFO_SIZE);
 104         fs_info->tree_root = tree_root;
 105         fs_info->extent_root = extent_root;
 106         fs_info->chunk_root = chunk_root;
 107         fs_info->dev_root = dev_root;
 108         fs_info->csum_root = csum_root;
 109
 110         fs_info->readonly = 1;
 111
 112         extent_io_tree_init(&fs_info->extent_cache);
 113         extent_io_tree_init(&fs_info->free_space_cache);
 114         extent_io_tree_init(&fs_info->block_group_cache);
 115         extent_io_tree_init(&fs_info->pinned_extents);
 116         extent_io_tree_init(&fs_info->pending_del);
 117         extent_io_tree_init(&fs_info->extent_ins);
 118         cache_tree_init(&fs_info->fs_root_cache);
 119
 120         cache_tree_init(&fs_info->mapping_tree.cache_tree);
 121
 122         mutex_init(&fs_info->fs_mutex);
 123         fs_info->fs_devices = fs_devices;
 124         INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
 125         INIT_LIST_HEAD(&fs_info->space_info);
 126
 127         __setup_root(4096, 4096, 4096, 4096, tree_root,
 128                      fs_info, BTRFS_ROOT_TREE_OBJECTID);
 129
 130         ret = btrfs_open_devices(fs_devices, O_RDONLY);
 131         if (ret)
 132                 goto out_cleanup;
 133
 134         fs_info->super_bytenr = BTRFS_SUPER_INFO_OFFSET;
 135         disk_super = fs_info->super_copy;
 136         ret = btrfs_read_dev_super(fs_devices->latest_bdev,
 137                                    disk_super, BTRFS_SUPER_INFO_OFFSET);
 138         if (ret) {
 139                 printk("No valid btrfs found\n");
 140                 goto out_devices;
 141         }
 142
 143         memcpy(fs_info->fsid, &disk_super->fsid, BTRFS_FSID_SIZE);
 144
 145
 146         features = btrfs_super_incompat_flags(disk_super) &
 147                    ~BTRFS_FEATURE_INCOMPAT_SUPP;
 148         if (features) {
 149                 printk("couldn't open because of unsupported "
 150                        "option features (%Lx).\n", features);
 151                 goto out_devices;
 152         }
 153
 154         features = btrfs_super_incompat_flags(disk_super);
 155         if (!(features & BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF)) {
 156                 features |= BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF;
 157                 btrfs_set_super_incompat_flags(disk_super, features);
 158         }
 159
 160         nodesize = btrfs_super_nodesize(disk_super);
 161         leafsize = btrfs_super_leafsize(disk_super);
 162         sectorsize = btrfs_super_sectorsize(disk_super);
 163         stripesize = btrfs_super_stripesize(disk_super);
 164         tree_root->nodesize = nodesize;
 165         tree_root->leafsize = leafsize;
 166         tree_root->sectorsize = sectorsize;
 167         tree_root->stripesize = stripesize;
 168
 169         ret = btrfs_read_sys_array(tree_root);
 170         if (ret)
 171                 goto out_devices;
 172         blocksize = btrfs_level_size(tree_root,
 173                                      btrfs_super_chunk_root_level(disk_super));
 174         generation = btrfs_super_chunk_root_generation(disk_super);
 175
 176         __setup_root(nodesize, leafsize, sectorsize, stripesize,
 177                      chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
 178
 179         chunk_root->node = read_tree_block(chunk_root,
 180                                            btrfs_super_chunk_root(disk_super),
 181                                            blocksize, generation);
 182         if (!chunk_root->node) {
 183                 printk("Couldn't read chunk root\n");
 184                 goto out_devices;
 185         }
 186
 187         read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
 188                  (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
 189                  BTRFS_UUID_SIZE);
 190
 191         if (!(btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)) {
 192                 ret = btrfs_read_chunk_tree(chunk_root);
 193                 if (ret)
 194                         goto out_chunk;
 195         }
 196
 197         return fs_info->chunk_root;
 198 out_chunk:
 199         free_extent_buffer(fs_info->chunk_root->node);
 200 out_devices:
 201         btrfs_close_devices(fs_info->fs_devices);
 202 out_cleanup:
 203         extent_io_tree_cleanup(&fs_info->extent_cache);
 204         extent_io_tree_cleanup(&fs_info->free_space_cache);
 205         extent_io_tree_cleanup(&fs_info->block_group_cache);
 206         extent_io_tree_cleanup(&fs_info->pinned_extents);
 207         extent_io_tree_cleanup(&fs_info->pending_del);
 208         extent_io_tree_cleanup(&fs_info->extent_ins);
 209 out:
 210         free(tree_root);
 211         free(extent_root);
 212         free(chunk_root);
 213         free(dev_root);
 214         free(csum_root);
 215         free(fs_info);
 216         return NULL;
 217 }
 218
 219 static int search_iobuf(struct btrfs_root *root, void *iobuf,
 220                         size_t iobuf_size, off_t offset)
 221 {
 222         u64 gen = btrfs_super_generation(root->fs_info->super_copy);
 223         u64 objectid = search_objectid;
 224         u32 size = btrfs_super_nodesize(root->fs_info->super_copy);
 225         u8 level = root->fs_info->super_copy->root_level;
 226         size_t block_off = 0;
 227
 228         while (block_off < iobuf_size) {
 229                 void *block = iobuf + block_off;
 230                 struct btrfs_header *header = block;
 231                 u64 h_byte, h_level, h_gen, h_owner;
 232
 233 //              printf("searching %Lu\n", offset + block_off);
 234                 h_byte = le64_to_cpu(header->bytenr);
 235                 h_owner = le64_to_cpu(header->owner);
 236                 h_level = header->level;
 237                 h_gen = le64_to_cpu(header->generation);
 238
 239                 if (h_owner != objectid)
 240                         goto next;
 241                 if (h_byte != (offset + block_off))
 242                         goto next;
 243                 if (h_level != level)
 244                         goto next;
 245                 if (csum_block(block, size)) {
 246                         fprintf(stderr, "Well block %Lu seems good, "
 247                                 "but the csum doesn't match\n",
 248                                 h_byte);
 249                         goto next;
 250                 }
 251                 if (h_gen != gen) {
 252                         fprintf(stderr, "Well block %Lu seems great, "
 253                                 "but generation doesn't match, "
 254                                 "have=%Lu, want=%Lu\n", h_byte, h_gen,
 255                                 gen);
 256                         goto next;
 257                 }
 258                 printf("Found tree root at %Lu\n", h_byte);
 259                 return 0;
 260 next:
 261                 block_off += size;
 262         }
 263
 264         return 1;
 265 }
 266
 267 static int read_physical(struct btrfs_root *root, int fd, u64 offset,
 268                          u64 bytenr, u64 len)
 269 {
 270         char *iobuf = malloc(len);
 271         ssize_t done;
 272         size_t total_read = 0;
 273         int ret = 1;
 274
 275         if (!iobuf) {
 276                 fprintf(stderr, "No memory\n");
 277                 return -1;
 278         }
 279
 280         while (total_read < len) {
 281                 done = pread64(fd, iobuf + total_read, len - total_read,
 282                                bytenr + total_read);
 283                 if (done < 0) {
 284                         fprintf(stderr, "Failed to read: %s\n",
 285                                 strerror(errno));
 286                         ret = -1;
 287                         goto out;
 288                 }
 289                 total_read += done;
 290         }
 291
 292         ret = search_iobuf(root, iobuf, total_read, offset);
 293 out:
 294         free(iobuf);
 295         return ret;
 296 }
 297
 298 static int find_root(struct btrfs_root *root)
 299 {
 300         struct btrfs_multi_bio *multi = NULL;
 301         struct btrfs_device *device;
 302         u64 metadata_offset = 0, metadata_size = 0;
 303         off_t offset = 0;
 304         off_t bytenr;
 305         int fd;
 306         int err;
 307         int ret = 1;
 308
 309         printf("Super think's the tree root is at %Lu, chunk root %Lu\n",
 310                btrfs_super_root(root->fs_info->super_copy),
 311                btrfs_super_chunk_root(root->fs_info->super_copy));
 312
 313         err = btrfs_next_metadata(&root->fs_info->mapping_tree,
 314                                   &metadata_offset, &metadata_size);
 315         if (err)
 316                 return ret;
 317
 318         offset = metadata_offset;
 319         while (1) {
 320                 u64 map_length = 4096;
 321                 u64 type;
 322
 323                 if (offset >
 324                     btrfs_super_total_bytes(root->fs_info->super_copy)) {
 325                         printf("Went past the fs size, exiting");
 326                         break;
 327                 }
 328                 if (offset >= (metadata_offset + metadata_size)) {
 329                         err = btrfs_next_metadata(&root->fs_info->mapping_tree,
 330                                                   &metadata_offset,
 331                                                   &metadata_size);
 332                         if (err) {
 333                                 printf("No more metdata to scan, exiting\n");
 334                                 break;
 335                         }
 336                         offset = metadata_offset;
 337                 }
 338                 err = __btrfs_map_block(&root->fs_info->mapping_tree, READ,
 339                                       offset, &map_length, &type,
 340                                       &multi, 0, NULL);
 341                 if (err) {
 342                         offset += map_length;
 343                         continue;
 344                 }
 345
 346                 if (!(type & BTRFS_BLOCK_GROUP_METADATA)) {
 347                         offset += map_length;
 348                         kfree(multi);
 349                         continue;
 350                 }
 351
 352                 device = multi->stripes[0].dev;
 353                 fd = device->fd;
 354                 bytenr = multi->stripes[0].physical;
 355                 kfree(multi);
 356
 357                 err = read_physical(root, fd, offset, bytenr, map_length);
 358                 if (!err) {
 359                         ret = 0;
 360                         break;
 361                 } else if (err < 0) {
 362                         ret = err;
 363                         break;
 364                 }
 365                 offset += map_length;
 366         }
 367         return ret;
 368 }
 369
 370 int main(int argc, char **argv)
 371 {
 372         struct btrfs_root *root;
 373         int dev_fd;
 374         int opt;
 375         int ret;
 376
 377         while ((opt = getopt(argc, argv, "o:")) != -1) {
 378                 switch(opt) {
 379                         case 'o':
 380                                 errno = 0;
 381                                 search_objectid = (u64)strtoll(optarg, NULL,
 382                                                                10);
 383                                 if (errno) {
 384                                         fprintf(stderr, "Error parsing "
 385                                                 "objectid\n");
 386                                         exit(1);
 387                                 }
 388                                 break;
 389                         default:
 390                                 usage();
 391                                 exit(1);
 392                 }
 393         }
 394
 395         if (optind >= argc) {
 396                 usage();
 397                 exit(1);
 398         }
 399
 400         dev_fd = open(argv[optind], O_RDONLY);
 401         if (dev_fd < 0) {
 402                 fprintf(stderr, "Failed to open device %s\n", argv[optind]);
 403                 exit(1);
 404         }
 405
 406         root = open_ctree_broken(dev_fd, argv[optind]);
 407         close(dev_fd);
 408
 409         if (!root) {
 410                 fprintf(stderr, "Open ctree failed\n");
 411                 exit(1);
 412         }
 413
 414         csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 415         ret = find_root(root);
 416         close_ctree(root);
 417         return ret;
 418 }