send-utils.c

   1 /*
   2  * Copyright (C) 2012 Alexander Block.  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 #include <unistd.h>
  20 #include <fcntl.h>
  21 #include <sys/ioctl.h>
  22 #include <uuid/uuid.h>
  23 #include <limits.h>
  24 #include <errno.h>
  25
  26 #include "ctree.h"
  27 #include "send-utils.h"
  28 #include "ioctl.h"
  29 #include "btrfs-list.h"
  30
  31 static int btrfs_subvolid_resolve_sub(int fd, char *path, size_t *path_len,
  32                                       u64 subvol_id);
  33
  34 static int btrfs_get_root_id_by_sub_path(int mnt_fd, const char *sub_path,
  35                                          u64 *root_id)
  36 {
  37         int ret;
  38         int subvol_fd;
  39
  40         subvol_fd = openat(mnt_fd, sub_path, O_RDONLY);
  41         if (subvol_fd < 0) {
  42                 ret = -errno;
  43                 fprintf(stderr, "ERROR: open %s failed. %s\n", sub_path,
  44                         strerror(-ret));
  45                 return ret;
  46         }
  47
  48         ret = btrfs_list_get_path_rootid(subvol_fd, root_id);
  49         close(subvol_fd);
  50         return ret;
  51 }
  52
  53 static int btrfs_read_root_item_raw(int mnt_fd, u64 root_id, size_t buf_len,
  54                                     u32 *read_len, void *buf)
  55 {
  56         int ret;
  57         struct btrfs_ioctl_search_args args;
  58         struct btrfs_ioctl_search_key *sk = &args.key;
  59         struct btrfs_ioctl_search_header *sh;
  60         unsigned long off = 0;
  61         int found = 0;
  62         int i;
  63
  64         *read_len = 0;
  65         memset(&args, 0, sizeof(args));
  66
  67         sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
  68
  69         /*
  70          * there may be more than one ROOT_ITEM key if there are
  71          * snapshots pending deletion, we have to loop through
  72          * them.
  73          */
  74         sk->min_objectid = root_id;
  75         sk->max_objectid = root_id;
  76         sk->max_type = BTRFS_ROOT_ITEM_KEY;
  77         sk->min_type = BTRFS_ROOT_ITEM_KEY;
  78         sk->max_offset = (u64)-1;
  79         sk->max_transid = (u64)-1;
  80         sk->nr_items = 4096;
  81
  82         while (1) {
  83                 ret = ioctl(mnt_fd, BTRFS_IOC_TREE_SEARCH, &args);
  84                 if (ret < 0) {
  85                         fprintf(stderr,
  86                                 "ERROR: can't perform the search - %s\n",
  87                                 strerror(errno));
  88                         return 0;
  89                 }
  90                 /* the ioctl returns the number of item it found in nr_items */
  91                 if (sk->nr_items == 0)
  92                         break;
  93
  94                 off = 0;
  95                 for (i = 0; i < sk->nr_items; i++) {
  96                         struct btrfs_root_item *item;
  97                         sh = (struct btrfs_ioctl_search_header *)(args.buf +
  98                                                                   off);
  99
 100                         off += sizeof(*sh);
 101                         item = (struct btrfs_root_item *)(args.buf + off);
 102                         off += btrfs_search_header_len(sh);
 103
 104                         sk->min_objectid = btrfs_search_header_objectid(sh);
 105                         sk->min_type = btrfs_search_header_type(sh);
 106                         sk->min_offset = btrfs_search_header_offset(sh);
 107
 108                         if (btrfs_search_header_objectid(sh) > root_id)
 109                                 break;
 110
 111                         if (btrfs_search_header_objectid(sh) == root_id &&
 112                             btrfs_search_header_type(sh) == BTRFS_ROOT_ITEM_KEY) {
 113                                 if (btrfs_search_header_len(sh) > buf_len) {
 114                                         /* btrfs-progs is too old for kernel */
 115                                         fprintf(stderr,
 116                                                 "ERROR: buf for read_root_item_raw() is too small, get newer btrfs tools!\n");
 117                                         return -EOVERFLOW;
 118                                 }
 119                                 memcpy(buf, item, btrfs_search_header_len(sh));
 120                                 *read_len = btrfs_search_header_len(sh);
 121                                 found = 1;
 122                         }
 123                 }
 124                 if (sk->min_offset < (u64)-1)
 125                         sk->min_offset++;
 126                 else
 127                         break;
 128
 129                 if (sk->min_type != BTRFS_ROOT_ITEM_KEY ||
 130                     sk->min_objectid != root_id)
 131                         break;
 132         }
 133
 134         return found ? 0 : -ENOENT;
 135 }
 136
 137 /*
 138  * Read a root item from the tree. In case we detect a root item smaller then
 139  * sizeof(root_item), we know it's an old version of the root structure and
 140  * initialize all new fields to zero. The same happens if we detect mismatching
 141  * generation numbers as then we know the root was once mounted with an older
 142  * kernel that was not aware of the root item structure change.
 143  */
 144 static int btrfs_read_root_item(int mnt_fd, u64 root_id,
 145                                 struct btrfs_root_item *item)
 146 {
 147         int ret;
 148         u32 read_len;
 149
 150         ret = btrfs_read_root_item_raw(mnt_fd, root_id, sizeof(*item),
 151                                        &read_len, item);
 152         if (ret)
 153                 return ret;
 154
 155         if (read_len < sizeof(*item) ||
 156             btrfs_root_generation(item) != btrfs_root_generation_v2(item))
 157                 memset(&item->generation_v2, 0,
 158                         sizeof(*item) - offsetof(struct btrfs_root_item,
 159                                                  generation_v2));
 160
 161         return 0;
 162 }
 163
 164 #ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
 165 static struct rb_node *tree_insert(struct rb_root *root,
 166                                    struct subvol_info *si,
 167                                    enum subvol_search_type type)
 168 {
 169         struct rb_node **p = &root->rb_node;
 170         struct rb_node *parent = NULL;
 171         struct subvol_info *entry;
 172         __s64 comp;
 173
 174         while (*p) {
 175                 parent = *p;
 176                 if (type == subvol_search_by_received_uuid) {
 177                         entry = rb_entry(parent, struct subvol_info,
 178                                         rb_received_node);
 179
 180                         comp = memcmp(entry->received_uuid, si->received_uuid,
 181                                         BTRFS_UUID_SIZE);
 182                         if (!comp) {
 183                                 if (entry->stransid < si->stransid)
 184                                         comp = -1;
 185                                 else if (entry->stransid > si->stransid)
 186                                         comp = 1;
 187                                 else
 188                                         comp = 0;
 189                         }
 190                 } else if (type == subvol_search_by_uuid) {
 191                         entry = rb_entry(parent, struct subvol_info,
 192                                         rb_local_node);
 193                         comp = memcmp(entry->uuid, si->uuid, BTRFS_UUID_SIZE);
 194                 } else if (type == subvol_search_by_root_id) {
 195                         entry = rb_entry(parent, struct subvol_info,
 196                                         rb_root_id_node);
 197                         comp = entry->root_id - si->root_id;
 198                 } else if (type == subvol_search_by_path) {
 199                         entry = rb_entry(parent, struct subvol_info,
 200                                         rb_path_node);
 201                         comp = strcmp(entry->path, si->path);
 202                 } else {
 203                         BUG();
 204                 }
 205
 206                 if (comp < 0)
 207                         p = &(*p)->rb_left;
 208                 else if (comp > 0)
 209                         p = &(*p)->rb_right;
 210                 else
 211                         return parent;
 212         }
 213
 214         if (type == subvol_search_by_received_uuid) {
 215                 rb_link_node(&si->rb_received_node, parent, p);
 216                 rb_insert_color(&si->rb_received_node, root);
 217         } else if (type == subvol_search_by_uuid) {
 218                 rb_link_node(&si->rb_local_node, parent, p);
 219                 rb_insert_color(&si->rb_local_node, root);
 220         } else if (type == subvol_search_by_root_id) {
 221                 rb_link_node(&si->rb_root_id_node, parent, p);
 222                 rb_insert_color(&si->rb_root_id_node, root);
 223         } else if (type == subvol_search_by_path) {
 224                 rb_link_node(&si->rb_path_node, parent, p);
 225                 rb_insert_color(&si->rb_path_node, root);
 226         }
 227         return NULL;
 228 }
 229 #endif
 230
 231 int btrfs_subvolid_resolve(int fd, char *path, size_t path_len, u64 subvol_id)
 232 {
 233         if (path_len < 1)
 234                 return -EOVERFLOW;
 235         path[0] = '\0';
 236         path_len--;
 237         path[path_len] = '\0';
 238         return btrfs_subvolid_resolve_sub(fd, path, &path_len, subvol_id);
 239 }
 240
 241 static int btrfs_subvolid_resolve_sub(int fd, char *path, size_t *path_len,
 242                                       u64 subvol_id)
 243 {
 244         int ret;
 245         struct btrfs_ioctl_search_args search_arg;
 246         struct btrfs_ioctl_ino_lookup_args ino_lookup_arg;
 247         struct btrfs_ioctl_search_header *search_header;
 248         struct btrfs_root_ref *backref_item;
 249
 250         if (subvol_id == BTRFS_FS_TREE_OBJECTID) {
 251                 if (*path_len < 1)
 252                         return -EOVERFLOW;
 253                 *path = '\0';
 254                 (*path_len)--;
 255                 return 0;
 256         }
 257
 258         memset(&search_arg, 0, sizeof(search_arg));
 259         search_arg.key.tree_id = BTRFS_ROOT_TREE_OBJECTID;
 260         search_arg.key.min_objectid = subvol_id;
 261         search_arg.key.max_objectid = subvol_id;
 262         search_arg.key.min_type = BTRFS_ROOT_BACKREF_KEY;
 263         search_arg.key.max_type = BTRFS_ROOT_BACKREF_KEY;
 264         search_arg.key.max_offset = (u64)-1;
 265         search_arg.key.max_transid = (u64)-1;
 266         search_arg.key.nr_items = 1;
 267         ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &search_arg);
 268         if (ret < 0) {
 269                 fprintf(stderr,
 270                         "ioctl(BTRFS_IOC_TREE_SEARCH, subvol_id %llu) ret=%d, error: %s\n",
 271                         (unsigned long long)subvol_id, ret, strerror(errno));
 272                 return ret;
 273         }
 274
 275         if (search_arg.key.nr_items < 1) {
 276                 fprintf(stderr,
 277                         "failed to lookup subvol_id %llu!\n",
 278                         (unsigned long long)subvol_id);
 279                 return -ENOENT;
 280         }
 281         search_header = (struct btrfs_ioctl_search_header *)search_arg.buf;
 282         backref_item = (struct btrfs_root_ref *)(search_header + 1);
 283         if (btrfs_search_header_offset(search_header)
 284             != BTRFS_FS_TREE_OBJECTID) {
 285                 int sub_ret;
 286
 287                 sub_ret = btrfs_subvolid_resolve_sub(fd, path, path_len,
 288                                 btrfs_search_header_offset(search_header));
 289                 if (sub_ret)
 290                         return sub_ret;
 291                 if (*path_len < 1)
 292                         return -EOVERFLOW;
 293                 strcat(path, "/");
 294                 (*path_len)--;
 295         }
 296
 297         if (btrfs_stack_root_ref_dirid(backref_item) !=
 298             BTRFS_FIRST_FREE_OBJECTID) {
 299                 int len;
 300
 301                 memset(&ino_lookup_arg, 0, sizeof(ino_lookup_arg));
 302                 ino_lookup_arg.treeid =
 303                         btrfs_search_header_offset(search_header);
 304                 ino_lookup_arg.objectid =
 305                         btrfs_stack_root_ref_dirid(backref_item);
 306                 ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP, &ino_lookup_arg);
 307                 if (ret < 0) {
 308                         fprintf(stderr,
 309                                 "ioctl(BTRFS_IOC_INO_LOOKUP) ret=%d, error: %s\n",
 310                                 ret, strerror(errno));
 311                         return ret;
 312                 }
 313
 314                 len = strlen(ino_lookup_arg.name);
 315                 if (*path_len < len)
 316                         return -EOVERFLOW;
 317                 strcat(path, ino_lookup_arg.name);
 318                 (*path_len) -= len;
 319         }
 320
 321         if (*path_len < btrfs_stack_root_ref_name_len(backref_item))
 322                 return -EOVERFLOW;
 323         strncat(path, (char *)(backref_item + 1),
 324                 btrfs_stack_root_ref_name_len(backref_item));
 325         (*path_len) -= btrfs_stack_root_ref_name_len(backref_item);
 326         return 0;
 327 }
 328
 329 #ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
 330 static int count_bytes(void *buf, int len, char b)
 331 {
 332         int cnt = 0;
 333         int i;
 334
 335         for (i = 0; i < len; i++) {
 336                 if (((char *)buf)[i] == b)
 337                         cnt++;
 338         }
 339         return cnt;
 340 }
 341
 342 void subvol_uuid_search_add(struct subvol_uuid_search *s,
 343                             struct subvol_info *si)
 344 {
 345         int cnt;
 346
 347         tree_insert(&s->root_id_subvols, si, subvol_search_by_root_id);
 348         tree_insert(&s->path_subvols, si, subvol_search_by_path);
 349
 350         cnt = count_bytes(si->uuid, BTRFS_UUID_SIZE, 0);
 351         if (cnt != BTRFS_UUID_SIZE)
 352                 tree_insert(&s->local_subvols, si, subvol_search_by_uuid);
 353         cnt = count_bytes(si->received_uuid, BTRFS_UUID_SIZE, 0);
 354         if (cnt != BTRFS_UUID_SIZE)
 355                 tree_insert(&s->received_subvols, si,
 356                                 subvol_search_by_received_uuid);
 357 }
 358
 359 static struct subvol_info *tree_search(struct rb_root *root,
 360                                        u64 root_id, const u8 *uuid,
 361                                        u64 stransid, const char *path,
 362                                        enum subvol_search_type type)
 363 {
 364         struct rb_node *n = root->rb_node;
 365         struct subvol_info *entry;
 366         __s64 comp;
 367
 368         while (n) {
 369                 if (type == subvol_search_by_received_uuid) {
 370                         entry = rb_entry(n, struct subvol_info,
 371                                         rb_received_node);
 372                         comp = memcmp(entry->received_uuid, uuid,
 373                                         BTRFS_UUID_SIZE);
 374                         if (!comp) {
 375                                 if (entry->stransid < stransid)
 376                                         comp = -1;
 377                                 else if (entry->stransid > stransid)
 378                                         comp = 1;
 379                                 else
 380                                         comp = 0;
 381                         }
 382                 } else if (type == subvol_search_by_uuid) {
 383                         entry = rb_entry(n, struct subvol_info, rb_local_node);
 384                         comp = memcmp(entry->uuid, uuid, BTRFS_UUID_SIZE);
 385                 } else if (type == subvol_search_by_root_id) {
 386                         entry = rb_entry(n, struct subvol_info,
 387                                          rb_root_id_node);
 388                         comp = entry->root_id - root_id;
 389                 } else if (type == subvol_search_by_path) {
 390                         entry = rb_entry(n, struct subvol_info, rb_path_node);
 391                         comp = strcmp(entry->path, path);
 392                 } else {
 393                         BUG();
 394                 }
 395                 if (comp < 0)
 396                         n = n->rb_left;
 397                 else if (comp > 0)
 398                         n = n->rb_right;
 399                 else
 400                         return entry;
 401         }
 402         return NULL;
 403 }
 404
 405 /*
 406  * this function will be only called if kernel doesn't support uuid tree.
 407  */
 408 static struct subvol_info *subvol_uuid_search_old(struct subvol_uuid_search *s,
 409                                        u64 root_id, const u8 *uuid, u64 transid,
 410                                        const char *path,
 411                                        enum subvol_search_type type)
 412 {
 413         struct rb_root *root;
 414         if (type == subvol_search_by_received_uuid)
 415                 root = &s->received_subvols;
 416         else if (type == subvol_search_by_uuid)
 417                 root = &s->local_subvols;
 418         else if (type == subvol_search_by_root_id)
 419                 root = &s->root_id_subvols;
 420         else if (type == subvol_search_by_path)
 421                 root = &s->path_subvols;
 422         else
 423                 return NULL;
 424         return tree_search(root, root_id, uuid, transid, path, type);
 425 }
 426 #else
 427 void subvol_uuid_search_add(struct subvol_uuid_search *s,
 428                             struct subvol_info *si)
 429 {
 430         if (si) {
 431                 free(si->path);
 432                 free(si);
 433         }
 434 }
 435 #endif
 436
 437 struct subvol_info *subvol_uuid_search(struct subvol_uuid_search *s,
 438                                        u64 root_id, const u8 *uuid, u64 transid,
 439                                        const char *path,
 440                                        enum subvol_search_type type)
 441 {
 442         int ret = 0;
 443         struct btrfs_root_item root_item;
 444         struct subvol_info *info = NULL;
 445
 446 #ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
 447         if (!s->uuid_tree_existed)
 448                 return subvol_uuid_search_old(s, root_id, uuid, transid,
 449                                              path, type);
 450 #endif
 451         switch (type) {
 452         case subvol_search_by_received_uuid:
 453                 ret = btrfs_lookup_uuid_received_subvol_item(s->mnt_fd, uuid,
 454                                                              &root_id);
 455                 break;
 456         case subvol_search_by_uuid:
 457                 ret = btrfs_lookup_uuid_subvol_item(s->mnt_fd, uuid, &root_id);
 458                 break;
 459         case subvol_search_by_root_id:
 460                 break;
 461         case subvol_search_by_path:
 462                 ret = btrfs_get_root_id_by_sub_path(s->mnt_fd, path, &root_id);
 463                 break;
 464         default:
 465                 ret = -EINVAL;
 466                 break;
 467         }
 468
 469         if (ret)
 470                 goto out;
 471
 472         ret = btrfs_read_root_item(s->mnt_fd, root_id, &root_item);
 473         if (ret)
 474                 goto out;
 475
 476         info = calloc(1, sizeof(*info));
 477         info->root_id = root_id;
 478         memcpy(info->uuid, root_item.uuid, BTRFS_UUID_SIZE);
 479         memcpy(info->received_uuid, root_item.received_uuid, BTRFS_UUID_SIZE);
 480         memcpy(info->parent_uuid, root_item.parent_uuid, BTRFS_UUID_SIZE);
 481         info->ctransid = btrfs_root_ctransid(&root_item);
 482         info->otransid = btrfs_root_otransid(&root_item);
 483         info->stransid = btrfs_root_stransid(&root_item);
 484         info->rtransid = btrfs_root_rtransid(&root_item);
 485         if (type == subvol_search_by_path) {
 486                 info->path = strdup(path);
 487         } else {
 488                 info->path = malloc(PATH_MAX);
 489                 ret = btrfs_subvolid_resolve(s->mnt_fd, info->path,
 490                                              PATH_MAX, root_id);
 491         }
 492
 493 out:
 494         if (ret && info) {
 495                 free(info->path);
 496                 free(info);
 497                 info = NULL;
 498         }
 499
 500         return info;
 501 }
 502
 503 #ifdef BTRFS_COMPAT_SEND_NO_UUID_TREE
 504 static int is_uuid_tree_supported(int fd)
 505 {
 506         int ret;
 507         struct btrfs_ioctl_search_args args;
 508         struct btrfs_ioctl_search_key *sk = &args.key;
 509
 510         memset(&args, 0, sizeof(args));
 511
 512         sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
 513
 514         sk->min_objectid = BTRFS_UUID_TREE_OBJECTID;
 515         sk->max_objectid = BTRFS_UUID_TREE_OBJECTID;
 516         sk->max_type = BTRFS_ROOT_ITEM_KEY;
 517         sk->min_type = BTRFS_ROOT_ITEM_KEY;
 518         sk->max_offset = (u64)-1;
 519         sk->max_transid = (u64)-1;
 520         sk->nr_items = 1;
 521
 522         ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
 523         if (ret < 0)
 524                 return ret;
 525
 526         /* the ioctl returns the number of item it found in nr_items */
 527         if (sk->nr_items == 0)
 528                 return 0;
 529
 530         return 1;
 531 }
 532
 533 /*
 534  * this function is mainly used to read all root items
 535  * it will be only used when we use older kernel which uuid
 536  * tree is not supported yet
 537  */
 538 int subvol_uuid_search_init(int mnt_fd, struct subvol_uuid_search *s)
 539 {
 540         int ret;
 541         struct btrfs_ioctl_search_args args;
 542         struct btrfs_ioctl_search_key *sk = &args.key;
 543         struct btrfs_ioctl_search_header *sh;
 544         struct btrfs_root_item *root_item_ptr;
 545         struct btrfs_root_item root_item = {};
 546         struct subvol_info *si = NULL;
 547         int root_item_valid = 0;
 548         unsigned long off = 0;
 549         int i;
 550         char *path;
 551
 552         s->mnt_fd = mnt_fd;
 553
 554         s->root_id_subvols = RB_ROOT;
 555         s->local_subvols = RB_ROOT;
 556         s->received_subvols = RB_ROOT;
 557         s->path_subvols = RB_ROOT;
 558
 559         ret = is_uuid_tree_supported(mnt_fd);
 560         if (ret < 0) {
 561                 fprintf(stderr,
 562                         "ERROR: check if we support uuid tree fails - %s\n",
 563                         strerror(errno));
 564                 return ret;
 565         } else if (ret) {
 566                 /* uuid tree is supported */
 567                 s->uuid_tree_existed = 1;
 568                 return 0;
 569         }
 570         memset(&args, 0, sizeof(args));
 571
 572         sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
 573
 574         sk->max_objectid = (u64)-1;
 575         sk->max_offset = (u64)-1;
 576         sk->max_transid = (u64)-1;
 577         sk->min_type = BTRFS_ROOT_ITEM_KEY;
 578         sk->max_type = BTRFS_ROOT_BACKREF_KEY;
 579         sk->nr_items = 4096;
 580
 581         while (1) {
 582                 ret = ioctl(mnt_fd, BTRFS_IOC_TREE_SEARCH, &args);
 583                 if (ret < 0) {
 584                         fprintf(stderr, "ERROR: can't perform the search - %s\n",
 585                                 strerror(errno));
 586                         return ret;
 587                 }
 588                 if (sk->nr_items == 0)
 589                         break;
 590
 591                 off = 0;
 592
 593                 for (i = 0; i < sk->nr_items; i++) {
 594                         sh = (struct btrfs_ioctl_search_header *)(args.buf +
 595                                                                   off);
 596                         off += sizeof(*sh);
 597
 598                         if ((btrfs_search_header_objectid(sh) != 5 &&
 599                              btrfs_search_header_objectid(sh)
 600                              < BTRFS_FIRST_FREE_OBJECTID) ||
 601                             btrfs_search_header_objectid(sh)
 602                             > BTRFS_LAST_FREE_OBJECTID) {
 603                                 goto skip;
 604                         }
 605
 606                         if (btrfs_search_header_type(sh)
 607                             == BTRFS_ROOT_ITEM_KEY) {
 608                                 /* older kernels don't have uuids+times */
 609                                 if (btrfs_search_header_len(sh)
 610                                     < sizeof(root_item)) {
 611                                         root_item_valid = 0;
 612                                         goto skip;
 613                                 }
 614                                 root_item_ptr = (struct btrfs_root_item *)
 615                                                 (args.buf + off);
 616                                 memcpy(&root_item, root_item_ptr,
 617                                                 sizeof(root_item));
 618                                 root_item_valid = 1;
 619                         } else if (btrfs_search_header_type(sh)
 620                                    == BTRFS_ROOT_BACKREF_KEY ||
 621                                    root_item_valid) {
 622                                 if (!root_item_valid)
 623                                         goto skip;
 624
 625                                 path = btrfs_list_path_for_root(mnt_fd,
 626                                         btrfs_search_header_objectid(sh));
 627                                 if (!path)
 628                                         path = strdup("");
 629                                 if (IS_ERR(path)) {
 630                                         ret = PTR_ERR(path);
 631                                         fprintf(stderr, "ERROR: unable to "
 632                                                         "resolve path "
 633                                                         "for root %llu\n",
 634                                                 btrfs_search_header_objectid(sh));
 635                                         goto out;
 636                                 }
 637
 638                                 si = calloc(1, sizeof(*si));
 639                                 si->root_id = btrfs_search_header_objectid(sh);
 640                                 memcpy(si->uuid, root_item.uuid,
 641                                                 BTRFS_UUID_SIZE);
 642                                 memcpy(si->parent_uuid, root_item.parent_uuid,
 643                                                 BTRFS_UUID_SIZE);
 644                                 memcpy(si->received_uuid,
 645                                                 root_item.received_uuid,
 646                                                 BTRFS_UUID_SIZE);
 647                                 si->ctransid = btrfs_root_ctransid(&root_item);
 648                                 si->otransid = btrfs_root_otransid(&root_item);
 649                                 si->stransid = btrfs_root_stransid(&root_item);
 650                                 si->rtransid = btrfs_root_rtransid(&root_item);
 651                                 si->path = path;
 652                                 subvol_uuid_search_add(s, si);
 653                                 root_item_valid = 0;
 654                         } else {
 655                                 goto skip;
 656                         }
 657
 658 skip:
 659                         off += btrfs_search_header_len(sh);
 660
 661                         /*
 662                          * record the mins in sk so we can make sure the
 663                          * next search doesn't repeat this root
 664                          */
 665                         sk->min_objectid = btrfs_search_header_objectid(sh);
 666                         sk->min_offset = btrfs_search_header_offset(sh);
 667                         sk->min_type = btrfs_search_header_type(sh);
 668                 }
 669                 sk->nr_items = 4096;
 670                 if (sk->min_offset < (u64)-1)
 671                         sk->min_offset++;
 672                 else if (sk->min_objectid < (u64)-1) {
 673                         sk->min_objectid++;
 674                         sk->min_offset = 0;
 675                         sk->min_type = 0;
 676                 } else
 677                         break;
 678         }
 679
 680 out:
 681         return ret;
 682 }
 683
 684 void subvol_uuid_search_finit(struct subvol_uuid_search *s)
 685 {
 686         struct rb_root *root = &s->root_id_subvols;
 687         struct rb_node *node;
 688
 689         if (!s->uuid_tree_existed)
 690                 return;
 691
 692         while ((node = rb_first(root))) {
 693                 struct subvol_info *entry =
 694                         rb_entry(node, struct subvol_info, rb_root_id_node);
 695
 696                 free(entry->path);
 697                 rb_erase(node, root);
 698                 free(entry);
 699         }
 700
 701         s->root_id_subvols = RB_ROOT;
 702         s->local_subvols = RB_ROOT;
 703         s->received_subvols = RB_ROOT;
 704         s->path_subvols = RB_ROOT;
 705 }
 706 #else
 707 int subvol_uuid_search_init(int mnt_fd, struct subvol_uuid_search *s)
 708 {
 709         s->mnt_fd = mnt_fd;
 710
 711         return 0;
 712 }
 713
 714 void subvol_uuid_search_finit(struct subvol_uuid_search *s)
 715 {
 716 }
 717 #endif
 718
 719 int path_cat_out(char *out, const char *p1, const char *p2)
 720 {
 721         int p1_len = strlen(p1);
 722         int p2_len = strlen(p2);
 723
 724         if (p1_len + p2_len + 2 >= PATH_MAX)
 725                 return -ENAMETOOLONG;
 726
 727         if (p1_len && p1[p1_len - 1] == '/')
 728                 p1_len--;
 729         if (p2_len && p2[p2_len - 1] == '/')
 730                 p2_len--;
 731         sprintf(out, "%.*s/%.*s", p1_len, p1, p2_len, p2);
 732
 733         return 0;
 734 }
 735
 736 __attribute__((deprecated))
 737 char *path_cat(const char *p1, const char *p2)
 738 {
 739         int p1_len = strlen(p1);
 740         int p2_len = strlen(p2);
 741         char *new = malloc(p1_len + p2_len + 2);
 742
 743         path_cat_out(new, p1, p2);
 744
 745         return new;
 746 }
 747
 748 int path_cat3_out(char *out, const char *p1, const char *p2, const char *p3)
 749 {
 750         int p1_len = strlen(p1);
 751         int p2_len = strlen(p2);
 752         int p3_len = strlen(p3);
 753
 754         if (p1_len + p2_len + p3_len + 3 >= PATH_MAX)
 755                 return -ENAMETOOLONG;
 756
 757         if (p1_len && p1[p1_len - 1] == '/')
 758                 p1_len--;
 759         if (p2_len && p2[p2_len - 1] == '/')
 760                 p2_len--;
 761         if (p3_len && p3[p3_len - 1] == '/')
 762                 p3_len--;
 763         sprintf(out, "%.*s/%.*s/%.*s", p1_len, p1, p2_len, p2, p3_len, p3);
 764
 765         return 0;
 766 }
 767
 768 __attribute__((deprecated))
 769 char *path_cat3(const char *p1, const char *p2, const char *p3)
 770 {
 771         int p1_len = strlen(p1);
 772         int p2_len = strlen(p2);
 773         int p3_len = strlen(p3);
 774         char *new = malloc(p1_len + p2_len + p3_len + 3);
 775
 776         path_cat3_out(new, p1, p2, p3);
 777
 778         return new;
 779 }