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                 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->super_copy = calloc(1, BTRFS_SUPER_INFO_SIZE);
 120         fs_info->tree_root = tree_root;
 121         fs_info->extent_root = extent_root;
 122         fs_info->chunk_root = chunk_root;
 123         fs_info->dev_root = dev_root;
 124         fs_info->csum_root = csum_root;
 125
 126         fs_info->readonly = 1;
 127
 128         extent_io_tree_init(&fs_info->extent_cache);
 129         extent_io_tree_init(&fs_info->free_space_cache);
 130         extent_io_tree_init(&fs_info->block_group_cache);
 131         extent_io_tree_init(&fs_info->pinned_extents);
 132         extent_io_tree_init(&fs_info->pending_del);
 133         extent_io_tree_init(&fs_info->extent_ins);
 134         cache_tree_init(&fs_info->fs_root_cache);
 135
 136         cache_tree_init(&fs_info->mapping_tree.cache_tree);
 137
 138         mutex_init(&fs_info->fs_mutex);
 139         fs_info->fs_devices = fs_devices;
 140         INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);
 141         INIT_LIST_HEAD(&fs_info->space_info);
 142
 143         __setup_root(4096, 4096, 4096, 4096, tree_root,
 144                      fs_info, BTRFS_ROOT_TREE_OBJECTID);
 145
 146         ret = btrfs_open_devices(fs_devices, O_RDONLY);
 147         if (ret)
 148                 goto out_cleanup;
 149
 150         fs_info->super_bytenr = BTRFS_SUPER_INFO_OFFSET;
 151         disk_super = fs_info->super_copy;
 152         ret = btrfs_read_dev_super(fs_devices->latest_bdev,
 153                                    disk_super, BTRFS_SUPER_INFO_OFFSET);
 154         if (ret) {
 155                 printk("No valid btrfs found\n");
 156                 goto out_devices;
 157         }
 158
 159         memcpy(fs_info->fsid, &disk_super->fsid, BTRFS_FSID_SIZE);
 160
 161
 162         features = btrfs_super_incompat_flags(disk_super) &
 163                    ~BTRFS_FEATURE_INCOMPAT_SUPP;
 164         if (features) {
 165                 printk("couldn't open because of unsupported "
 166                        "option features (%Lx).\n", features);
 167                 goto out_devices;
 168         }
 169
 170         features = btrfs_super_incompat_flags(disk_super);
 171         if (!(features & BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF)) {
 172                 features |= BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF;
 173                 btrfs_set_super_incompat_flags(disk_super, features);
 174         }
 175
 176         nodesize = btrfs_super_nodesize(disk_super);
 177         leafsize = btrfs_super_leafsize(disk_super);
 178         sectorsize = btrfs_super_sectorsize(disk_super);
 179         stripesize = btrfs_super_stripesize(disk_super);
 180         tree_root->nodesize = nodesize;
 181         tree_root->leafsize = leafsize;
 182         tree_root->sectorsize = sectorsize;
 183         tree_root->stripesize = stripesize;
 184
 185         ret = btrfs_read_sys_array(tree_root);
 186         if (ret)
 187                 goto out_devices;
 188         blocksize = btrfs_level_size(tree_root,
 189                                      btrfs_super_chunk_root_level(disk_super));
 190         generation = btrfs_super_chunk_root_generation(disk_super);
 191
 192         __setup_root(nodesize, leafsize, sectorsize, stripesize,
 193                      chunk_root, fs_info, BTRFS_CHUNK_TREE_OBJECTID);
 194
 195         chunk_root->node = read_tree_block(chunk_root,
 196                                            btrfs_super_chunk_root(disk_super),
 197                                            blocksize, generation);
 198         if (!chunk_root->node) {
 199                 printk("Couldn't read chunk root\n");
 200                 goto out_devices;
 201         }
 202
 203         read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
 204                  (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
 205                  BTRFS_UUID_SIZE);
 206
 207         if (!(btrfs_super_flags(disk_super) & BTRFS_SUPER_FLAG_METADUMP)) {
 208                 ret = btrfs_read_chunk_tree(chunk_root);
 209                 if (ret)
 210                         goto out_chunk;
 211         }
 212
 213         return fs_info->chunk_root;
 214 out_chunk:
 215         free_extent_buffer(fs_info->chunk_root->node);
 216 out_devices:
 217         close_all_devices(fs_info);
 218 out_cleanup:
 219         extent_io_tree_cleanup(&fs_info->extent_cache);
 220         extent_io_tree_cleanup(&fs_info->free_space_cache);
 221         extent_io_tree_cleanup(&fs_info->block_group_cache);
 222         extent_io_tree_cleanup(&fs_info->pinned_extents);
 223         extent_io_tree_cleanup(&fs_info->pending_del);
 224         extent_io_tree_cleanup(&fs_info->extent_ins);
 225 out:
 226         free(tree_root);
 227         free(extent_root);
 228         free(chunk_root);
 229         free(dev_root);
 230         free(csum_root);
 231         free(fs_info);
 232         return NULL;
 233 }
 234
 235 static int search_iobuf(struct btrfs_root *root, void *iobuf,
 236                         size_t iobuf_size, off_t offset)
 237 {
 238         u64 gen = btrfs_super_generation(root->fs_info->super_copy);
 239         u64 objectid = search_objectid;
 240         u32 size = btrfs_super_nodesize(root->fs_info->super_copy);
 241         u8 level = root->fs_info->super_copy->root_level;
 242         size_t block_off = 0;
 243
 244         while (block_off < iobuf_size) {
 245                 void *block = iobuf + block_off;
 246                 struct btrfs_header *header = block;
 247                 u64 h_byte, h_level, h_gen, h_owner;
 248
 249 //              printf("searching %Lu\n", offset + block_off);
 250                 h_byte = le64_to_cpu(header->bytenr);
 251                 h_owner = le64_to_cpu(header->owner);
 252                 h_level = header->level;
 253                 h_gen = le64_to_cpu(header->generation);
 254
 255                 if (h_owner != objectid)
 256                         goto next;
 257                 if (h_byte != (offset + block_off))
 258                         goto next;
 259                 if (h_level != level)
 260                         goto next;
 261                 if (csum_block(block, size)) {
 262                         fprintf(stderr, "Well block %Lu seems good, "
 263                                 "but the csum doesn't match\n",
 264                                 h_byte);
 265                         goto next;
 266                 }
 267                 if (h_gen != gen) {
 268                         fprintf(stderr, "Well block %Lu seems great, "
 269                                 "but generation doesn't match, "
 270                                 "have=%Lu, want=%Lu\n", h_byte, h_gen,
 271                                 gen);
 272                         goto next;
 273                 }
 274                 printf("Found tree root at %Lu\n", h_byte);
 275                 return 0;
 276 next:
 277                 block_off += size;
 278         }
 279
 280         return 1;
 281 }
 282
 283 static int read_physical(struct btrfs_root *root, int fd, u64 offset,
 284                          u64 bytenr, u64 len)
 285 {
 286         char *iobuf = malloc(len);
 287         ssize_t done;
 288         size_t total_read = 0;
 289         int ret = 1;
 290
 291         if (!iobuf) {
 292                 fprintf(stderr, "No memory\n");
 293                 return -1;
 294         }
 295
 296         while (total_read < len) {
 297                 done = pread64(fd, iobuf + total_read, len - total_read,
 298                                bytenr + total_read);
 299                 if (done < 0) {
 300                         fprintf(stderr, "Failed to read: %s\n",
 301                                 strerror(errno));
 302                         ret = -1;
 303                         goto out;
 304                 }
 305                 total_read += done;
 306         }
 307
 308         ret = search_iobuf(root, iobuf, total_read, offset);
 309 out:
 310         free(iobuf);
 311         return ret;
 312 }
 313
 314 static int find_root(struct btrfs_root *root)
 315 {
 316         struct btrfs_multi_bio *multi = NULL;
 317         struct btrfs_device *device;
 318         u64 metadata_offset = 0, metadata_size = 0;
 319         off_t offset = 0;
 320         off_t bytenr;
 321         int fd;
 322         int err;
 323         int ret = 1;
 324
 325         printf("Super think's the tree root is at %Lu, chunk root %Lu\n",
 326                btrfs_super_root(root->fs_info->super_copy),
 327                btrfs_super_chunk_root(root->fs_info->super_copy));
 328
 329         err = btrfs_next_metadata(&root->fs_info->mapping_tree,
 330                                   &metadata_offset, &metadata_size);
 331         if (err)
 332                 return ret;
 333
 334         offset = metadata_offset;
 335         while (1) {
 336                 u64 map_length = 4096;
 337                 u64 type;
 338
 339                 if (offset >
 340                     btrfs_super_total_bytes(root->fs_info->super_copy)) {
 341                         printf("Went past the fs size, exiting");
 342                         break;
 343                 }
 344                 if (offset >= (metadata_offset + metadata_size)) {
 345                         err = btrfs_next_metadata(&root->fs_info->mapping_tree,
 346                                                   &metadata_offset,
 347                                                   &metadata_size);
 348                         if (err) {
 349                                 printf("No more metdata to scan, exiting\n");
 350                                 break;
 351                         }
 352                         offset = metadata_offset;
 353                 }
 354                 err = __btrfs_map_block(&root->fs_info->mapping_tree, READ,
 355                                       offset, &map_length, &type,
 356                                       &multi, 0, NULL);
 357                 if (err) {
 358                         offset += map_length;
 359                         continue;
 360                 }
 361
 362                 if (!(type & BTRFS_BLOCK_GROUP_METADATA)) {
 363                         offset += map_length;
 364                         kfree(multi);
 365                         continue;
 366                 }
 367
 368                 device = multi->stripes[0].dev;
 369                 fd = device->fd;
 370                 bytenr = multi->stripes[0].physical;
 371                 kfree(multi);
 372
 373                 err = read_physical(root, fd, offset, bytenr, map_length);
 374                 if (!err) {
 375                         ret = 0;
 376                         break;
 377                 } else if (err < 0) {
 378                         ret = err;
 379                         break;
 380                 }
 381                 offset += map_length;
 382         }
 383         return ret;
 384 }
 385
 386 int main(int argc, char **argv)
 387 {
 388         struct btrfs_root *root;
 389         int dev_fd;
 390         int opt;
 391         int ret;
 392
 393         while ((opt = getopt(argc, argv, "o:")) != -1) {
 394                 switch(opt) {
 395                         case 'o':
 396                                 errno = 0;
 397                                 search_objectid = (u64)strtoll(optarg, NULL,
 398                                                                10);
 399                                 if (errno) {
 400                                         fprintf(stderr, "Error parsing "
 401                                                 "objectid\n");
 402                                         exit(1);
 403                                 }
 404                                 break;
 405                         default:
 406                                 usage();
 407                                 exit(1);
 408                 }
 409         }
 410
 411         if (optind >= argc) {
 412                 usage();
 413                 exit(1);
 414         }
 415
 416         dev_fd = open(argv[optind], O_RDONLY);
 417         if (dev_fd < 0) {
 418                 fprintf(stderr, "Failed to open device %s\n", argv[optind]);
 419                 exit(1);
 420         }
 421
 422         root = open_ctree_broken(dev_fd, argv[optind]);
 423         close(dev_fd);
 424
 425         if (!root) {
 426                 fprintf(stderr, "Open ctree failed\n");
 427                 exit(1);
 428         }
 429
 430         csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 431         ret = find_root(root);
 432         close_ctree(root);
 433         return ret;
 434 }