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 static u64 search_generation = 0;
  41 static unsigned long search_level = 0;
  42
  43 static void usage(void)
  44 {
  45         fprintf(stderr, "Usage: find-roots [-o search_objectid] "
  46                 "[ -g search_generation ] [ -l search_level ] <device>\n");
  47 }
  48
  49 static int csum_block(void *buf, u32 len)
  50 {
  51         char *result;
  52         u32 crc = ~(u32)0;
  53         int ret = 0;
  54
  55         result = malloc(csum_size * sizeof(char));
  56         if (!result) {
  57                 fprintf(stderr, "No memory\n");
  58                 return 1;
  59         }
  60
  61         len -= BTRFS_CSUM_SIZE;
  62         crc = crc32c(crc, buf + BTRFS_CSUM_SIZE, len);
  63         btrfs_csum_final(crc, result);
  64
  65         if (memcmp(buf, result, csum_size))
  66                 ret = 1;
  67         free(result);
  68         return ret;
  69 }
  70
  71 static struct btrfs_root *open_ctree_broken(int fd, const char *device)
  72 {
  73         struct btrfs_fs_info *fs_info;
  74         struct btrfs_super_block *disk_super;
  75         struct btrfs_fs_devices *fs_devices = NULL;
  76         struct extent_buffer *eb;
  77         int ret;
  78
  79         fs_info = btrfs_new_fs_info(0, BTRFS_SUPER_INFO_OFFSET);
  80         if (!fs_info) {
  81                 fprintf(stderr, "Failed to allocate memory for fs_info\n");
  82                 return NULL;
  83         }
  84
  85         ret = btrfs_scan_fs_devices(fd, device, &fs_devices, 0, 1, 1);
  86         if (ret)
  87                 goto out;
  88
  89         fs_info->fs_devices = fs_devices;
  90
  91         ret = btrfs_open_devices(fs_devices, O_RDONLY);
  92         if (ret)
  93                 goto out_devices;
  94
  95         disk_super = fs_info->super_copy;
  96         ret = btrfs_read_dev_super(fs_devices->latest_bdev,
  97                                    disk_super, fs_info->super_bytenr, 1);
  98         if (ret) {
  99                 printk("No valid btrfs found\n");
 100                 goto out_devices;
 101         }
 102
 103         memcpy(fs_info->fsid, &disk_super->fsid, BTRFS_FSID_SIZE);
 104
 105         ret = btrfs_check_fs_compatibility(disk_super, 0);
 106         if (ret)
 107                 goto out_devices;
 108
 109         ret = btrfs_setup_chunk_tree_and_device_map(fs_info);
 110         if (ret)
 111                 goto out_chunk;
 112
 113         eb = fs_info->chunk_root->node;
 114         read_extent_buffer(eb, fs_info->chunk_tree_uuid,
 115                            btrfs_header_chunk_tree_uuid(eb), BTRFS_UUID_SIZE);
 116
 117         return fs_info->chunk_root;
 118 out_chunk:
 119         free_extent_buffer(fs_info->chunk_root->node);
 120         btrfs_cleanup_all_caches(fs_info);
 121 out_devices:
 122         btrfs_close_devices(fs_info->fs_devices);
 123 out:
 124         btrfs_free_fs_info(fs_info);
 125         return NULL;
 126 }
 127
 128 static int search_iobuf(struct btrfs_root *root, void *iobuf,
 129                         size_t iobuf_size, off_t offset)
 130 {
 131         u64 gen = search_generation;
 132         u64 objectid = search_objectid;
 133         u32 size = btrfs_super_nodesize(root->fs_info->super_copy);
 134         u8 level = search_level;
 135         size_t block_off = 0;
 136
 137         while (block_off < iobuf_size) {
 138                 void *block = iobuf + block_off;
 139                 struct btrfs_header *header = block;
 140                 u64 h_byte, h_level, h_gen, h_owner;
 141
 142 //              printf("searching %Lu\n", offset + block_off);
 143                 h_byte = btrfs_stack_header_bytenr(header);
 144                 h_owner = btrfs_stack_header_owner(header);
 145                 h_level = header->level;
 146                 h_gen = btrfs_stack_header_generation(header);
 147
 148                 if (h_owner != objectid)
 149                         goto next;
 150                 if (h_byte != (offset + block_off))
 151                         goto next;
 152                 if (h_level < level)
 153                         goto next;
 154                 level = h_level;
 155                 if (csum_block(block, size)) {
 156                         fprintf(stderr, "Well block %Lu seems good, "
 157                                 "but the csum doesn't match\n",
 158                                 h_byte);
 159                         goto next;
 160                 }
 161                 if (h_gen != gen) {
 162                         fprintf(stderr, "Well block %Lu seems great, "
 163                                 "but generation doesn't match, "
 164                                 "have=%Lu, want=%Lu level %Lu\n", h_byte,
 165                                 h_gen, gen, h_level);
 166                         goto next;
 167                 }
 168                 printf("Found tree root at %Lu gen %Lu level %Lu\n", h_byte,
 169                        h_gen, h_level);
 170                 return 0;
 171 next:
 172                 block_off += size;
 173         }
 174
 175         return 1;
 176 }
 177
 178 static int read_physical(struct btrfs_root *root, int fd, u64 offset,
 179                          u64 bytenr, u64 len)
 180 {
 181         char *iobuf = malloc(len);
 182         ssize_t done;
 183         size_t total_read = 0;
 184         int ret = 1;
 185
 186         if (!iobuf) {
 187                 fprintf(stderr, "No memory\n");
 188                 return -1;
 189         }
 190
 191         while (total_read < len) {
 192                 done = pread64(fd, iobuf + total_read, len - total_read,
 193                                bytenr + total_read);
 194                 if (done < 0) {
 195                         fprintf(stderr, "Failed to read: %s\n",
 196                                 strerror(errno));
 197                         ret = -1;
 198                         goto out;
 199                 }
 200                 total_read += done;
 201         }
 202
 203         ret = search_iobuf(root, iobuf, total_read, offset);
 204 out:
 205         free(iobuf);
 206         return ret;
 207 }
 208
 209 static int find_root(struct btrfs_root *root)
 210 {
 211         struct btrfs_multi_bio *multi = NULL;
 212         struct btrfs_device *device;
 213         u64 metadata_offset = 0, metadata_size = 0;
 214         off_t offset = 0;
 215         off_t bytenr;
 216         int fd;
 217         int err;
 218         int ret = 1;
 219
 220         printf("Super think's the tree root is at %Lu, chunk root %Lu\n",
 221                btrfs_super_root(root->fs_info->super_copy),
 222                btrfs_super_chunk_root(root->fs_info->super_copy));
 223
 224         err = btrfs_next_metadata(&root->fs_info->mapping_tree,
 225                                   &metadata_offset, &metadata_size);
 226         if (err)
 227                 return ret;
 228
 229         offset = metadata_offset;
 230         while (1) {
 231                 u64 map_length = 4096;
 232                 u64 type;
 233
 234                 if (offset >
 235                     btrfs_super_total_bytes(root->fs_info->super_copy)) {
 236                         printf("Went past the fs size, exiting");
 237                         break;
 238                 }
 239                 if (offset >= (metadata_offset + metadata_size)) {
 240                         err = btrfs_next_metadata(&root->fs_info->mapping_tree,
 241                                                   &metadata_offset,
 242                                                   &metadata_size);
 243                         if (err) {
 244                                 printf("No more metdata to scan, exiting\n");
 245                                 break;
 246                         }
 247                         offset = metadata_offset;
 248                 }
 249                 err = __btrfs_map_block(&root->fs_info->mapping_tree, READ,
 250                                       offset, &map_length, &type,
 251                                       &multi, 0, NULL);
 252                 if (err) {
 253                         offset += map_length;
 254                         continue;
 255                 }
 256
 257                 if (!(type & BTRFS_BLOCK_GROUP_METADATA)) {
 258                         offset += map_length;
 259                         kfree(multi);
 260                         continue;
 261                 }
 262
 263                 device = multi->stripes[0].dev;
 264                 fd = device->fd;
 265                 bytenr = multi->stripes[0].physical;
 266                 kfree(multi);
 267
 268                 err = read_physical(root, fd, offset, bytenr, map_length);
 269                 if (!err) {
 270                         ret = 0;
 271                         break;
 272                 } else if (err < 0) {
 273                         ret = err;
 274                         break;
 275                 }
 276                 offset += map_length;
 277         }
 278         return ret;
 279 }
 280
 281 int main(int argc, char **argv)
 282 {
 283         struct btrfs_root *root;
 284         int dev_fd;
 285         int opt;
 286         int ret;
 287
 288         while ((opt = getopt(argc, argv, "l:o:g:")) != -1) {
 289                 switch(opt) {
 290                         case 'o':
 291                                 search_objectid = arg_strtou64(optarg);
 292                                 break;
 293                         case 'g':
 294                                 search_generation = arg_strtou64(optarg);
 295                                 break;
 296                         case 'l':
 297                                 search_level = arg_strtou64(optarg);
 298                                 break;
 299                         default:
 300                                 usage();
 301                                 exit(1);
 302                 }
 303         }
 304
 305         if (optind >= argc) {
 306                 usage();
 307                 exit(1);
 308         }
 309
 310         dev_fd = open(argv[optind], O_RDONLY);
 311         if (dev_fd < 0) {
 312                 fprintf(stderr, "Failed to open device %s\n", argv[optind]);
 313                 exit(1);
 314         }
 315
 316         root = open_ctree_broken(dev_fd, argv[optind]);
 317         close(dev_fd);
 318
 319         if (!root) {
 320                 fprintf(stderr, "Open ctree failed\n");
 321                 exit(1);
 322         }
 323
 324         if (search_generation == 0)
 325                 search_generation = btrfs_super_generation(root->fs_info->super_copy);
 326
 327         csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 328         ret = find_root(root);
 329         close_ctree(root);
 330         return ret;
 331 }