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()
  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);
  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);
  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                            (unsigned long)btrfs_header_chunk_tree_uuid(eb),
 116                            BTRFS_UUID_SIZE);
 117
 118         return fs_info->chunk_root;
 119 out_chunk:
 120         free_extent_buffer(fs_info->chunk_root->node);
 121         btrfs_cleanup_all_caches(fs_info);
 122 out_devices:
 123         btrfs_close_devices(fs_info->fs_devices);
 124 out:
 125         btrfs_free_fs_info(fs_info);
 126         return NULL;
 127 }
 128
 129 static int search_iobuf(struct btrfs_root *root, void *iobuf,
 130                         size_t iobuf_size, off_t offset)
 131 {
 132         u64 gen = search_generation;
 133         u64 objectid = search_objectid;
 134         u32 size = btrfs_super_nodesize(root->fs_info->super_copy);
 135         u8 level = search_level;
 136         size_t block_off = 0;
 137
 138         while (block_off < iobuf_size) {
 139                 void *block = iobuf + block_off;
 140                 struct btrfs_header *header = block;
 141                 u64 h_byte, h_level, h_gen, h_owner;
 142
 143 //              printf("searching %Lu\n", offset + block_off);
 144                 h_byte = btrfs_stack_header_bytenr(header);
 145                 h_owner = btrfs_stack_header_owner(header);
 146                 h_level = header->level;
 147                 h_gen = btrfs_stack_header_generation(header);
 148
 149                 if (h_owner != objectid)
 150                         goto next;
 151                 if (h_byte != (offset + block_off))
 152                         goto next;
 153                 if (h_level < level)
 154                         goto next;
 155                 level = h_level;
 156                 if (csum_block(block, size)) {
 157                         fprintf(stderr, "Well block %Lu seems good, "
 158                                 "but the csum doesn't match\n",
 159                                 h_byte);
 160                         goto next;
 161                 }
 162                 if (h_gen != gen) {
 163                         fprintf(stderr, "Well block %Lu seems great, "
 164                                 "but generation doesn't match, "
 165                                 "have=%Lu, want=%Lu level %Lu\n", h_byte,
 166                                 h_gen, gen, h_level);
 167                         goto next;
 168                 }
 169                 printf("Found tree root at %Lu gen %Lu level %Lu\n", h_byte,
 170                        h_gen, h_level);
 171                 return 0;
 172 next:
 173                 block_off += size;
 174         }
 175
 176         return 1;
 177 }
 178
 179 static int read_physical(struct btrfs_root *root, int fd, u64 offset,
 180                          u64 bytenr, u64 len)
 181 {
 182         char *iobuf = malloc(len);
 183         ssize_t done;
 184         size_t total_read = 0;
 185         int ret = 1;
 186
 187         if (!iobuf) {
 188                 fprintf(stderr, "No memory\n");
 189                 return -1;
 190         }
 191
 192         while (total_read < len) {
 193                 done = pread64(fd, iobuf + total_read, len - total_read,
 194                                bytenr + total_read);
 195                 if (done < 0) {
 196                         fprintf(stderr, "Failed to read: %s\n",
 197                                 strerror(errno));
 198                         ret = -1;
 199                         goto out;
 200                 }
 201                 total_read += done;
 202         }
 203
 204         ret = search_iobuf(root, iobuf, total_read, offset);
 205 out:
 206         free(iobuf);
 207         return ret;
 208 }
 209
 210 static int find_root(struct btrfs_root *root)
 211 {
 212         struct btrfs_multi_bio *multi = NULL;
 213         struct btrfs_device *device;
 214         u64 metadata_offset = 0, metadata_size = 0;
 215         off_t offset = 0;
 216         off_t bytenr;
 217         int fd;
 218         int err;
 219         int ret = 1;
 220
 221         printf("Super think's the tree root is at %Lu, chunk root %Lu\n",
 222                btrfs_super_root(root->fs_info->super_copy),
 223                btrfs_super_chunk_root(root->fs_info->super_copy));
 224
 225         err = btrfs_next_metadata(&root->fs_info->mapping_tree,
 226                                   &metadata_offset, &metadata_size);
 227         if (err)
 228                 return ret;
 229
 230         offset = metadata_offset;
 231         while (1) {
 232                 u64 map_length = 4096;
 233                 u64 type;
 234
 235                 if (offset >
 236                     btrfs_super_total_bytes(root->fs_info->super_copy)) {
 237                         printf("Went past the fs size, exiting");
 238                         break;
 239                 }
 240                 if (offset >= (metadata_offset + metadata_size)) {
 241                         err = btrfs_next_metadata(&root->fs_info->mapping_tree,
 242                                                   &metadata_offset,
 243                                                   &metadata_size);
 244                         if (err) {
 245                                 printf("No more metdata to scan, exiting\n");
 246                                 break;
 247                         }
 248                         offset = metadata_offset;
 249                 }
 250                 err = __btrfs_map_block(&root->fs_info->mapping_tree, READ,
 251                                       offset, &map_length, &type,
 252                                       &multi, 0, NULL);
 253                 if (err) {
 254                         offset += map_length;
 255                         continue;
 256                 }
 257
 258                 if (!(type & BTRFS_BLOCK_GROUP_METADATA)) {
 259                         offset += map_length;
 260                         kfree(multi);
 261                         continue;
 262                 }
 263
 264                 device = multi->stripes[0].dev;
 265                 fd = device->fd;
 266                 bytenr = multi->stripes[0].physical;
 267                 kfree(multi);
 268
 269                 err = read_physical(root, fd, offset, bytenr, map_length);
 270                 if (!err) {
 271                         ret = 0;
 272                         break;
 273                 } else if (err < 0) {
 274                         ret = err;
 275                         break;
 276                 }
 277                 offset += map_length;
 278         }
 279         return ret;
 280 }
 281
 282 int main(int argc, char **argv)
 283 {
 284         struct btrfs_root *root;
 285         int dev_fd;
 286         int opt;
 287         int ret;
 288
 289         while ((opt = getopt(argc, argv, "l:o:g:")) != -1) {
 290                 switch(opt) {
 291                         errno = 0;
 292                         case 'o':
 293                                 search_objectid = (u64)strtoll(optarg, NULL,
 294                                                                10);
 295                                 if (errno) {
 296                                         fprintf(stderr, "Error parsing "
 297                                                 "objectid\n");
 298                                         exit(1);
 299                                 }
 300                                 break;
 301                         case 'g':
 302                                 search_generation = (u64)strtoll(optarg, NULL,
 303                                                                10);
 304                                 if (errno) {
 305                                         fprintf(stderr, "Error parsing "
 306                                                 "generation\n");
 307                                         exit(1);
 308                                 }
 309                                 break;
 310                         case 'l':
 311                                 search_level = strtol(optarg, NULL, 10);
 312                                 if (errno) {
 313                                         fprintf(stderr, "Error parsing "
 314                                                 "level\n");
 315                                         exit(1);
 316                                 }
 317                                 break;
 318                         default:
 319                                 usage();
 320                                 exit(1);
 321                 }
 322         }
 323
 324         if (optind >= argc) {
 325                 usage();
 326                 exit(1);
 327         }
 328
 329         dev_fd = open(argv[optind], O_RDONLY);
 330         if (dev_fd < 0) {
 331                 fprintf(stderr, "Failed to open device %s\n", argv[optind]);
 332                 exit(1);
 333         }
 334
 335         root = open_ctree_broken(dev_fd, argv[optind]);
 336         close(dev_fd);
 337
 338         if (!root) {
 339                 fprintf(stderr, "Open ctree failed\n");
 340                 exit(1);
 341         }
 342
 343         if (search_generation == 0)
 344                 search_generation = btrfs_super_generation(root->fs_info->super_copy);
 345
 346         csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 347         ret = find_root(root);
 348         close_ctree(root);
 349         return ret;
 350 }