Pileus Git - ~andy/linux/blob - fs/btrfs/backref.c

   1 /*
   2  * Copyright (C) 2011 STRATO.  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 <linux/vmalloc.h>
  20 #include "ctree.h"
  21 #include "disk-io.h"
  22 #include "backref.h"
  23 #include "ulist.h"
  24 #include "transaction.h"
  25 #include "delayed-ref.h"
  26 #include "locking.h"
  27
  28 struct extent_inode_elem {
  29         u64 inum;
  30         u64 offset;
  31         struct extent_inode_elem *next;
  32 };
  33
  34 static int check_extent_in_eb(struct btrfs_key *key, struct extent_buffer *eb,
  35                                 struct btrfs_file_extent_item *fi,
  36                                 u64 extent_item_pos,
  37                                 struct extent_inode_elem **eie)
  38 {
  39         u64 offset = 0;
  40         struct extent_inode_elem *e;
  41
  42         if (!btrfs_file_extent_compression(eb, fi) &&
  43             !btrfs_file_extent_encryption(eb, fi) &&
  44             !btrfs_file_extent_other_encoding(eb, fi)) {
  45                 u64 data_offset;
  46                 u64 data_len;
  47
  48                 data_offset = btrfs_file_extent_offset(eb, fi);
  49                 data_len = btrfs_file_extent_num_bytes(eb, fi);
  50
  51                 if (extent_item_pos < data_offset ||
  52                     extent_item_pos >= data_offset + data_len)
  53                         return 1;
  54                 offset = extent_item_pos - data_offset;
  55         }
  56
  57         e = kmalloc(sizeof(*e), GFP_NOFS);
  58         if (!e)
  59                 return -ENOMEM;
  60
  61         e->next = *eie;
  62         e->inum = key->objectid;
  63         e->offset = key->offset + offset;
  64         *eie = e;
  65
  66         return 0;
  67 }
  68
  69 static int find_extent_in_eb(struct extent_buffer *eb, u64 wanted_disk_byte,
  70                                 u64 extent_item_pos,
  71                                 struct extent_inode_elem **eie)
  72 {
  73         u64 disk_byte;
  74         struct btrfs_key key;
  75         struct btrfs_file_extent_item *fi;
  76         int slot;
  77         int nritems;
  78         int extent_type;
  79         int ret;
  80
  81         /*
  82          * from the shared data ref, we only have the leaf but we need
  83          * the key. thus, we must look into all items and see that we
  84          * find one (some) with a reference to our extent item.
  85          */
  86         nritems = btrfs_header_nritems(eb);
  87         for (slot = 0; slot < nritems; ++slot) {
  88                 btrfs_item_key_to_cpu(eb, &key, slot);
  89                 if (key.type != BTRFS_EXTENT_DATA_KEY)
  90                         continue;
  91                 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
  92                 extent_type = btrfs_file_extent_type(eb, fi);
  93                 if (extent_type == BTRFS_FILE_EXTENT_INLINE)
  94                         continue;
  95                 /* don't skip BTRFS_FILE_EXTENT_PREALLOC, we can handle that */
  96                 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
  97                 if (disk_byte != wanted_disk_byte)
  98                         continue;
  99
 100                 ret = check_extent_in_eb(&key, eb, fi, extent_item_pos, eie);
 101                 if (ret < 0)
 102                         return ret;
 103         }
 104
 105         return 0;
 106 }
 107
 108 /*
 109  * this structure records all encountered refs on the way up to the root
 110  */
 111 struct __prelim_ref {
 112         struct list_head list;
 113         u64 root_id;
 114         struct btrfs_key key_for_search;
 115         int level;
 116         int count;
 117         struct extent_inode_elem *inode_list;
 118         u64 parent;
 119         u64 wanted_disk_byte;
 120 };
 121
 122 static struct kmem_cache *btrfs_prelim_ref_cache;
 123
 124 int __init btrfs_prelim_ref_init(void)
 125 {
 126         btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
 127                                         sizeof(struct __prelim_ref),
 128                                         0,
 129                                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
 130                                         NULL);
 131         if (!btrfs_prelim_ref_cache)
 132                 return -ENOMEM;
 133         return 0;
 134 }
 135
 136 void btrfs_prelim_ref_exit(void)
 137 {
 138         if (btrfs_prelim_ref_cache)
 139                 kmem_cache_destroy(btrfs_prelim_ref_cache);
 140 }
 141
 142 /*
 143  * the rules for all callers of this function are:
 144  * - obtaining the parent is the goal
 145  * - if you add a key, you must know that it is a correct key
 146  * - if you cannot add the parent or a correct key, then we will look into the
 147  *   block later to set a correct key
 148  *
 149  * delayed refs
 150  * ============
 151  *        backref type | shared | indirect | shared | indirect
 152  * information         |   tree |     tree |   data |     data
 153  * --------------------+--------+----------+--------+----------
 154  *      parent logical |    y   |     -    |    -   |     -
 155  *      key to resolve |    -   |     y    |    y   |     y
 156  *  tree block logical |    -   |     -    |    -   |     -
 157  *  root for resolving |    y   |     y    |    y   |     y
 158  *
 159  * - column 1:       we've the parent -> done
 160  * - column 2, 3, 4: we use the key to find the parent
 161  *
 162  * on disk refs (inline or keyed)
 163  * ==============================
 164  *        backref type | shared | indirect | shared | indirect
 165  * information         |   tree |     tree |   data |     data
 166  * --------------------+--------+----------+--------+----------
 167  *      parent logical |    y   |     -    |    y   |     -
 168  *      key to resolve |    -   |     -    |    -   |     y
 169  *  tree block logical |    y   |     y    |    y   |     y
 170  *  root for resolving |    -   |     y    |    y   |     y
 171  *
 172  * - column 1, 3: we've the parent -> done
 173  * - column 2:    we take the first key from the block to find the parent
 174  *                (see __add_missing_keys)
 175  * - column 4:    we use the key to find the parent
 176  *
 177  * additional information that's available but not required to find the parent
 178  * block might help in merging entries to gain some speed.
 179  */
 180
 181 static int __add_prelim_ref(struct list_head *head, u64 root_id,
 182                             struct btrfs_key *key, int level,
 183                             u64 parent, u64 wanted_disk_byte, int count,
 184                             gfp_t gfp_mask)
 185 {
 186         struct __prelim_ref *ref;
 187
 188         if (root_id == BTRFS_DATA_RELOC_TREE_OBJECTID)
 189                 return 0;
 190
 191         ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
 192         if (!ref)
 193                 return -ENOMEM;
 194
 195         ref->root_id = root_id;
 196         if (key)
 197                 ref->key_for_search = *key;
 198         else
 199                 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
 200
 201         ref->inode_list = NULL;
 202         ref->level = level;
 203         ref->count = count;
 204         ref->parent = parent;
 205         ref->wanted_disk_byte = wanted_disk_byte;
 206         list_add_tail(&ref->list, head);
 207
 208         return 0;
 209 }
 210
 211 static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
 212                                 struct ulist *parents, int level,
 213                                 struct btrfs_key *key_for_search, u64 time_seq,
 214                                 u64 wanted_disk_byte,
 215                                 const u64 *extent_item_pos)
 216 {
 217         int ret = 0;
 218         int slot;
 219         struct extent_buffer *eb;
 220         struct btrfs_key key;
 221         struct btrfs_file_extent_item *fi;
 222         struct extent_inode_elem *eie = NULL, *old = NULL;
 223         u64 disk_byte;
 224
 225         if (level != 0) {
 226                 eb = path->nodes[level];
 227                 ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
 228                 if (ret < 0)
 229                         return ret;
 230                 return 0;
 231         }
 232
 233         /*
 234          * We normally enter this function with the path already pointing to
 235          * the first item to check. But sometimes, we may enter it with
 236          * slot==nritems. In that case, go to the next leaf before we continue.
 237          */
 238         if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
 239                 ret = btrfs_next_old_leaf(root, path, time_seq);
 240
 241         while (!ret) {
 242                 eb = path->nodes[0];
 243                 slot = path->slots[0];
 244
 245                 btrfs_item_key_to_cpu(eb, &key, slot);
 246
 247                 if (key.objectid != key_for_search->objectid ||
 248                     key.type != BTRFS_EXTENT_DATA_KEY)
 249                         break;
 250
 251                 fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
 252                 disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
 253
 254                 if (disk_byte == wanted_disk_byte) {
 255                         eie = NULL;
 256                         old = NULL;
 257                         if (extent_item_pos) {
 258                                 ret = check_extent_in_eb(&key, eb, fi,
 259                                                 *extent_item_pos,
 260                                                 &eie);
 261                                 if (ret < 0)
 262                                         break;
 263                         }
 264                         if (ret > 0)
 265                                 goto next;
 266                         ret = ulist_add_merge(parents, eb->start,
 267                                               (uintptr_t)eie,
 268                                               (u64 *)&old, GFP_NOFS);
 269                         if (ret < 0)
 270                                 break;
 271                         if (!ret && extent_item_pos) {
 272                                 while (old->next)
 273                                         old = old->next;
 274                                 old->next = eie;
 275                         }
 276                 }
 277 next:
 278                 ret = btrfs_next_old_item(root, path, time_seq);
 279         }
 280
 281         if (ret > 0)
 282                 ret = 0;
 283         return ret;
 284 }
 285
 286 /*
 287  * resolve an indirect backref in the form (root_id, key, level)
 288  * to a logical address
 289  */
 290 static int __resolve_indirect_ref(struct btrfs_fs_info *fs_info,
 291                                   struct btrfs_path *path, u64 time_seq,
 292                                   struct __prelim_ref *ref,
 293                                   struct ulist *parents,
 294                                   const u64 *extent_item_pos)
 295 {
 296         struct btrfs_root *root;
 297         struct btrfs_key root_key;
 298         struct extent_buffer *eb;
 299         int ret = 0;
 300         int root_level;
 301         int level = ref->level;
 302
 303         root_key.objectid = ref->root_id;
 304         root_key.type = BTRFS_ROOT_ITEM_KEY;
 305         root_key.offset = (u64)-1;
 306         root = btrfs_read_fs_root_no_name(fs_info, &root_key);
 307         if (IS_ERR(root)) {
 308                 ret = PTR_ERR(root);
 309                 goto out;
 310         }
 311
 312         root_level = btrfs_old_root_level(root, time_seq);
 313
 314         if (root_level + 1 == level)
 315                 goto out;
 316
 317         path->lowest_level = level;
 318         ret = btrfs_search_old_slot(root, &ref->key_for_search, path, time_seq);
 319         pr_debug("search slot in root %llu (level %d, ref count %d) returned "
 320                  "%d for key (%llu %u %llu)\n",
 321                  ref->root_id, level, ref->count, ret,
 322                  ref->key_for_search.objectid, ref->key_for_search.type,
 323                  ref->key_for_search.offset);
 324         if (ret < 0)
 325                 goto out;
 326
 327         eb = path->nodes[level];
 328         while (!eb) {
 329                 if (WARN_ON(!level)) {
 330                         ret = 1;
 331                         goto out;
 332                 }
 333                 level--;
 334                 eb = path->nodes[level];
 335         }
 336
 337         ret = add_all_parents(root, path, parents, level, &ref->key_for_search,
 338                                 time_seq, ref->wanted_disk_byte,
 339                                 extent_item_pos);
 340 out:
 341         path->lowest_level = 0;
 342         btrfs_release_path(path);
 343         return ret;
 344 }
 345
 346 /*
 347  * resolve all indirect backrefs from the list
 348  */
 349 static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
 350                                    struct btrfs_path *path, u64 time_seq,
 351                                    struct list_head *head,
 352                                    const u64 *extent_item_pos)
 353 {
 354         int err;
 355         int ret = 0;
 356         struct __prelim_ref *ref;
 357         struct __prelim_ref *ref_safe;
 358         struct __prelim_ref *new_ref;
 359         struct ulist *parents;
 360         struct ulist_node *node;
 361         struct ulist_iterator uiter;
 362
 363         parents = ulist_alloc(GFP_NOFS);
 364         if (!parents)
 365                 return -ENOMEM;
 366
 367         /*
 368          * _safe allows us to insert directly after the current item without
 369          * iterating over the newly inserted items.
 370          * we're also allowed to re-assign ref during iteration.
 371          */
 372         list_for_each_entry_safe(ref, ref_safe, head, list) {
 373                 if (ref->parent)        /* already direct */
 374                         continue;
 375                 if (ref->count == 0)
 376                         continue;
 377                 err = __resolve_indirect_ref(fs_info, path, time_seq, ref,
 378                                              parents, extent_item_pos);
 379                 if (err == -ENOMEM)
 380                         goto out;
 381                 if (err)
 382                         continue;
 383
 384                 /* we put the first parent into the ref at hand */
 385                 ULIST_ITER_INIT(&uiter);
 386                 node = ulist_next(parents, &uiter);
 387                 ref->parent = node ? node->val : 0;
 388                 ref->inode_list = node ?
 389                         (struct extent_inode_elem *)(uintptr_t)node->aux : NULL;
 390
 391                 /* additional parents require new refs being added here */
 392                 while ((node = ulist_next(parents, &uiter))) {
 393                         new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
 394                                                    GFP_NOFS);
 395                         if (!new_ref) {
 396                                 ret = -ENOMEM;
 397                                 goto out;
 398                         }
 399                         memcpy(new_ref, ref, sizeof(*ref));
 400                         new_ref->parent = node->val;
 401                         new_ref->inode_list = (struct extent_inode_elem *)
 402                                                         (uintptr_t)node->aux;
 403                         list_add(&new_ref->list, &ref->list);
 404                 }
 405                 ulist_reinit(parents);
 406         }
 407 out:
 408         ulist_free(parents);
 409         return ret;
 410 }
 411
 412 static inline int ref_for_same_block(struct __prelim_ref *ref1,
 413                                      struct __prelim_ref *ref2)
 414 {
 415         if (ref1->level != ref2->level)
 416                 return 0;
 417         if (ref1->root_id != ref2->root_id)
 418                 return 0;
 419         if (ref1->key_for_search.type != ref2->key_for_search.type)
 420                 return 0;
 421         if (ref1->key_for_search.objectid != ref2->key_for_search.objectid)
 422                 return 0;
 423         if (ref1->key_for_search.offset != ref2->key_for_search.offset)
 424                 return 0;
 425         if (ref1->parent != ref2->parent)
 426                 return 0;
 427
 428         return 1;
 429 }
 430
 431 /*
 432  * read tree blocks and add keys where required.
 433  */
 434 static int __add_missing_keys(struct btrfs_fs_info *fs_info,
 435                               struct list_head *head)
 436 {
 437         struct list_head *pos;
 438         struct extent_buffer *eb;
 439
 440         list_for_each(pos, head) {
 441                 struct __prelim_ref *ref;
 442                 ref = list_entry(pos, struct __prelim_ref, list);
 443
 444                 if (ref->parent)
 445                         continue;
 446                 if (ref->key_for_search.type)
 447                         continue;
 448                 BUG_ON(!ref->wanted_disk_byte);
 449                 eb = read_tree_block(fs_info->tree_root, ref->wanted_disk_byte,
 450                                      fs_info->tree_root->leafsize, 0);
 451                 if (!eb || !extent_buffer_uptodate(eb)) {
 452                         free_extent_buffer(eb);
 453                         return -EIO;
 454                 }
 455                 btrfs_tree_read_lock(eb);
 456                 if (btrfs_header_level(eb) == 0)
 457                         btrfs_item_key_to_cpu(eb, &ref->key_for_search, 0);
 458                 else
 459                         btrfs_node_key_to_cpu(eb, &ref->key_for_search, 0);
 460                 btrfs_tree_read_unlock(eb);
 461                 free_extent_buffer(eb);
 462         }
 463         return 0;
 464 }
 465
 466 /*
 467  * merge two lists of backrefs and adjust counts accordingly
 468  *
 469  * mode = 1: merge identical keys, if key is set
 470  *    FIXME: if we add more keys in __add_prelim_ref, we can merge more here.
 471  *           additionally, we could even add a key range for the blocks we
 472  *           looked into to merge even more (-> replace unresolved refs by those
 473  *           having a parent).
 474  * mode = 2: merge identical parents
 475  */
 476 static void __merge_refs(struct list_head *head, int mode)
 477 {
 478         struct list_head *pos1;
 479
 480         list_for_each(pos1, head) {
 481                 struct list_head *n2;
 482                 struct list_head *pos2;
 483                 struct __prelim_ref *ref1;
 484
 485                 ref1 = list_entry(pos1, struct __prelim_ref, list);
 486
 487                 for (pos2 = pos1->next, n2 = pos2->next; pos2 != head;
 488                      pos2 = n2, n2 = pos2->next) {
 489                         struct __prelim_ref *ref2;
 490                         struct __prelim_ref *xchg;
 491                         struct extent_inode_elem *eie;
 492
 493                         ref2 = list_entry(pos2, struct __prelim_ref, list);
 494
 495                         if (mode == 1) {
 496                                 if (!ref_for_same_block(ref1, ref2))
 497                                         continue;
 498                                 if (!ref1->parent && ref2->parent) {
 499                                         xchg = ref1;
 500                                         ref1 = ref2;
 501                                         ref2 = xchg;
 502                                 }
 503                         } else {
 504                                 if (ref1->parent != ref2->parent)
 505                                         continue;
 506                         }
 507
 508                         eie = ref1->inode_list;
 509                         while (eie && eie->next)
 510                                 eie = eie->next;
 511                         if (eie)
 512                                 eie->next = ref2->inode_list;
 513                         else
 514                                 ref1->inode_list = ref2->inode_list;
 515                         ref1->count += ref2->count;
 516
 517                         list_del(&ref2->list);
 518                         kmem_cache_free(btrfs_prelim_ref_cache, ref2);
 519                 }
 520
 521         }
 522 }
 523
 524 /*
 525  * add all currently queued delayed refs from this head whose seq nr is
 526  * smaller or equal that seq to the list
 527  */
 528 static int __add_delayed_refs(struct btrfs_delayed_ref_head *head, u64 seq,
 529                               struct list_head *prefs)
 530 {
 531         struct btrfs_delayed_extent_op *extent_op = head->extent_op;
 532         struct rb_node *n = &head->node.rb_node;
 533         struct btrfs_key key;
 534         struct btrfs_key op_key = {0};
 535         int sgn;
 536         int ret = 0;
 537
 538         if (extent_op && extent_op->update_key)
 539                 btrfs_disk_key_to_cpu(&op_key, &extent_op->key);
 540
 541         while ((n = rb_prev(n))) {
 542                 struct btrfs_delayed_ref_node *node;
 543                 node = rb_entry(n, struct btrfs_delayed_ref_node,
 544                                 rb_node);
 545                 if (node->bytenr != head->node.bytenr)
 546                         break;
 547                 WARN_ON(node->is_head);
 548
 549                 if (node->seq > seq)
 550                         continue;
 551
 552                 switch (node->action) {
 553                 case BTRFS_ADD_DELAYED_EXTENT:
 554                 case BTRFS_UPDATE_DELAYED_HEAD:
 555                         WARN_ON(1);
 556                         continue;
 557                 case BTRFS_ADD_DELAYED_REF:
 558                         sgn = 1;
 559                         break;
 560                 case BTRFS_DROP_DELAYED_REF:
 561                         sgn = -1;
 562                         break;
 563                 default:
 564                         BUG_ON(1);
 565                 }
 566                 switch (node->type) {
 567                 case BTRFS_TREE_BLOCK_REF_KEY: {
 568                         struct btrfs_delayed_tree_ref *ref;
 569
 570                         ref = btrfs_delayed_node_to_tree_ref(node);
 571                         ret = __add_prelim_ref(prefs, ref->root, &op_key,
 572                                                ref->level + 1, 0, node->bytenr,
 573                                                node->ref_mod * sgn, GFP_ATOMIC);
 574                         break;
 575                 }
 576                 case BTRFS_SHARED_BLOCK_REF_KEY: {
 577                         struct btrfs_delayed_tree_ref *ref;
 578
 579                         ref = btrfs_delayed_node_to_tree_ref(node);
 580                         ret = __add_prelim_ref(prefs, ref->root, NULL,
 581                                                ref->level + 1, ref->parent,
 582                                                node->bytenr,
 583                                                node->ref_mod * sgn, GFP_ATOMIC);
 584                         break;
 585                 }
 586                 case BTRFS_EXTENT_DATA_REF_KEY: {
 587                         struct btrfs_delayed_data_ref *ref;
 588                         ref = btrfs_delayed_node_to_data_ref(node);
 589
 590                         key.objectid = ref->objectid;
 591                         key.type = BTRFS_EXTENT_DATA_KEY;
 592                         key.offset = ref->offset;
 593                         ret = __add_prelim_ref(prefs, ref->root, &key, 0, 0,
 594                                                node->bytenr,
 595                                                node->ref_mod * sgn, GFP_ATOMIC);
 596                         break;
 597                 }
 598                 case BTRFS_SHARED_DATA_REF_KEY: {
 599                         struct btrfs_delayed_data_ref *ref;
 600
 601                         ref = btrfs_delayed_node_to_data_ref(node);
 602
 603                         key.objectid = ref->objectid;
 604                         key.type = BTRFS_EXTENT_DATA_KEY;
 605                         key.offset = ref->offset;
 606                         ret = __add_prelim_ref(prefs, ref->root, &key, 0,
 607                                                ref->parent, node->bytenr,
 608                                                node->ref_mod * sgn, GFP_ATOMIC);
 609                         break;
 610                 }
 611                 default:
 612                         WARN_ON(1);
 613                 }
 614                 if (ret)
 615                         return ret;
 616         }
 617
 618         return 0;
 619 }
 620
 621 /*
 622  * add all inline backrefs for bytenr to the list
 623  */
 624 static int __add_inline_refs(struct btrfs_fs_info *fs_info,
 625                              struct btrfs_path *path, u64 bytenr,
 626                              int *info_level, struct list_head *prefs)
 627 {
 628         int ret = 0;
 629         int slot;
 630         struct extent_buffer *leaf;
 631         struct btrfs_key key;
 632         struct btrfs_key found_key;
 633         unsigned long ptr;
 634         unsigned long end;
 635         struct btrfs_extent_item *ei;
 636         u64 flags;
 637         u64 item_size;
 638
 639         /*
 640          * enumerate all inline refs
 641          */
 642         leaf = path->nodes[0];
 643         slot = path->slots[0];
 644
 645         item_size = btrfs_item_size_nr(leaf, slot);
 646         BUG_ON(item_size < sizeof(*ei));
 647
 648         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 649         flags = btrfs_extent_flags(leaf, ei);
 650         btrfs_item_key_to_cpu(leaf, &found_key, slot);
 651
 652         ptr = (unsigned long)(ei + 1);
 653         end = (unsigned long)ei + item_size;
 654
 655         if (found_key.type == BTRFS_EXTENT_ITEM_KEY &&
 656             flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 657                 struct btrfs_tree_block_info *info;
 658
 659                 info = (struct btrfs_tree_block_info *)ptr;
 660                 *info_level = btrfs_tree_block_level(leaf, info);
 661                 ptr += sizeof(struct btrfs_tree_block_info);
 662                 BUG_ON(ptr > end);
 663         } else if (found_key.type == BTRFS_METADATA_ITEM_KEY) {
 664                 *info_level = found_key.offset;
 665         } else {
 666                 BUG_ON(!(flags & BTRFS_EXTENT_FLAG_DATA));
 667         }
 668
 669         while (ptr < end) {
 670                 struct btrfs_extent_inline_ref *iref;
 671                 u64 offset;
 672                 int type;
 673
 674                 iref = (struct btrfs_extent_inline_ref *)ptr;
 675                 type = btrfs_extent_inline_ref_type(leaf, iref);
 676                 offset = btrfs_extent_inline_ref_offset(leaf, iref);
 677
 678                 switch (type) {
 679                 case BTRFS_SHARED_BLOCK_REF_KEY:
 680                         ret = __add_prelim_ref(prefs, 0, NULL,
 681                                                 *info_level + 1, offset,
 682                                                 bytenr, 1, GFP_NOFS);
 683                         break;
 684                 case BTRFS_SHARED_DATA_REF_KEY: {
 685                         struct btrfs_shared_data_ref *sdref;
 686                         int count;
 687
 688                         sdref = (struct btrfs_shared_data_ref *)(iref + 1);
 689                         count = btrfs_shared_data_ref_count(leaf, sdref);
 690                         ret = __add_prelim_ref(prefs, 0, NULL, 0, offset,
 691                                                bytenr, count, GFP_NOFS);
 692                         break;
 693                 }
 694                 case BTRFS_TREE_BLOCK_REF_KEY:
 695                         ret = __add_prelim_ref(prefs, offset, NULL,
 696                                                *info_level + 1, 0,
 697                                                bytenr, 1, GFP_NOFS);
 698                         break;
 699                 case BTRFS_EXTENT_DATA_REF_KEY: {
 700                         struct btrfs_extent_data_ref *dref;
 701                         int count;
 702                         u64 root;
 703
 704                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
 705                         count = btrfs_extent_data_ref_count(leaf, dref);
 706                         key.objectid = btrfs_extent_data_ref_objectid(leaf,
 707                                                                       dref);
 708                         key.type = BTRFS_EXTENT_DATA_KEY;
 709                         key.offset = btrfs_extent_data_ref_offset(leaf, dref);
 710                         root = btrfs_extent_data_ref_root(leaf, dref);
 711                         ret = __add_prelim_ref(prefs, root, &key, 0, 0,
 712                                                bytenr, count, GFP_NOFS);
 713                         break;
 714                 }
 715                 default:
 716                         WARN_ON(1);
 717                 }
 718                 if (ret)
 719                         return ret;
 720                 ptr += btrfs_extent_inline_ref_size(type);
 721         }
 722
 723         return 0;
 724 }
 725
 726 /*
 727  * add all non-inline backrefs for bytenr to the list
 728  */
 729 static int __add_keyed_refs(struct btrfs_fs_info *fs_info,
 730                             struct btrfs_path *path, u64 bytenr,
 731                             int info_level, struct list_head *prefs)
 732 {
 733         struct btrfs_root *extent_root = fs_info->extent_root;
 734         int ret;
 735         int slot;
 736         struct extent_buffer *leaf;
 737         struct btrfs_key key;
 738
 739         while (1) {
 740                 ret = btrfs_next_item(extent_root, path);
 741                 if (ret < 0)
 742                         break;
 743                 if (ret) {
 744                         ret = 0;
 745                         break;
 746                 }
 747
 748                 slot = path->slots[0];
 749                 leaf = path->nodes[0];
 750                 btrfs_item_key_to_cpu(leaf, &key, slot);
 751
 752                 if (key.objectid != bytenr)
 753                         break;
 754                 if (key.type < BTRFS_TREE_BLOCK_REF_KEY)
 755                         continue;
 756                 if (key.type > BTRFS_SHARED_DATA_REF_KEY)
 757                         break;
 758
 759                 switch (key.type) {
 760                 case BTRFS_SHARED_BLOCK_REF_KEY:
 761                         ret = __add_prelim_ref(prefs, 0, NULL,
 762                                                 info_level + 1, key.offset,
 763                                                 bytenr, 1, GFP_NOFS);
 764                         break;
 765                 case BTRFS_SHARED_DATA_REF_KEY: {
 766                         struct btrfs_shared_data_ref *sdref;
 767                         int count;
 768
 769                         sdref = btrfs_item_ptr(leaf, slot,
 770                                               struct btrfs_shared_data_ref);
 771                         count = btrfs_shared_data_ref_count(leaf, sdref);
 772                         ret = __add_prelim_ref(prefs, 0, NULL, 0, key.offset,
 773                                                 bytenr, count, GFP_NOFS);
 774                         break;
 775                 }
 776                 case BTRFS_TREE_BLOCK_REF_KEY:
 777                         ret = __add_prelim_ref(prefs, key.offset, NULL,
 778                                                info_level + 1, 0,
 779                                                bytenr, 1, GFP_NOFS);
 780                         break;
 781                 case BTRFS_EXTENT_DATA_REF_KEY: {
 782                         struct btrfs_extent_data_ref *dref;
 783                         int count;
 784                         u64 root;
 785
 786                         dref = btrfs_item_ptr(leaf, slot,
 787                                               struct btrfs_extent_data_ref);
 788                         count = btrfs_extent_data_ref_count(leaf, dref);
 789                         key.objectid = btrfs_extent_data_ref_objectid(leaf,
 790                                                                       dref);
 791                         key.type = BTRFS_EXTENT_DATA_KEY;
 792                         key.offset = btrfs_extent_data_ref_offset(leaf, dref);
 793                         root = btrfs_extent_data_ref_root(leaf, dref);
 794                         ret = __add_prelim_ref(prefs, root, &key, 0, 0,
 795                                                bytenr, count, GFP_NOFS);
 796                         break;
 797                 }
 798                 default:
 799                         WARN_ON(1);
 800                 }
 801                 if (ret)
 802                         return ret;
 803
 804         }
 805
 806         return ret;
 807 }
 808
 809 /*
 810  * this adds all existing backrefs (inline backrefs, backrefs and delayed
 811  * refs) for the given bytenr to the refs list, merges duplicates and resolves
 812  * indirect refs to their parent bytenr.
 813  * When roots are found, they're added to the roots list
 814  *
 815  * FIXME some caching might speed things up
 816  */
 817 static int find_parent_nodes(struct btrfs_trans_handle *trans,
 818                              struct btrfs_fs_info *fs_info, u64 bytenr,
 819                              u64 time_seq, struct ulist *refs,
 820                              struct ulist *roots, const u64 *extent_item_pos)
 821 {
 822         struct btrfs_key key;
 823         struct btrfs_path *path;
 824         struct btrfs_delayed_ref_root *delayed_refs = NULL;
 825         struct btrfs_delayed_ref_head *head;
 826         int info_level = 0;
 827         int ret;
 828         struct list_head prefs_delayed;
 829         struct list_head prefs;
 830         struct __prelim_ref *ref;
 831
 832         INIT_LIST_HEAD(&prefs);
 833         INIT_LIST_HEAD(&prefs_delayed);
 834
 835         key.objectid = bytenr;
 836         key.offset = (u64)-1;
 837         if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
 838                 key.type = BTRFS_METADATA_ITEM_KEY;
 839         else
 840                 key.type = BTRFS_EXTENT_ITEM_KEY;
 841
 842         path = btrfs_alloc_path();
 843         if (!path)
 844                 return -ENOMEM;
 845         if (!trans)
 846                 path->search_commit_root = 1;
 847
 848         /*
 849          * grab both a lock on the path and a lock on the delayed ref head.
 850          * We need both to get a consistent picture of how the refs look
 851          * at a specified point in time
 852          */
 853 again:
 854         head = NULL;
 855
 856         ret = btrfs_search_slot(trans, fs_info->extent_root, &key, path, 0, 0);
 857         if (ret < 0)
 858                 goto out;
 859         BUG_ON(ret == 0);
 860
 861         if (trans) {
 862                 /*
 863                  * look if there are updates for this ref queued and lock the
 864                  * head
 865                  */
 866                 delayed_refs = &trans->transaction->delayed_refs;
 867                 spin_lock(&delayed_refs->lock);
 868                 head = btrfs_find_delayed_ref_head(trans, bytenr);
 869                 if (head) {
 870                         if (!mutex_trylock(&head->mutex)) {
 871                                 atomic_inc(&head->node.refs);
 872                                 spin_unlock(&delayed_refs->lock);
 873
 874                                 btrfs_release_path(path);
 875
 876                                 /*
 877                                  * Mutex was contended, block until it's
 878                                  * released and try again
 879                                  */
 880                                 mutex_lock(&head->mutex);
 881                                 mutex_unlock(&head->mutex);
 882                                 btrfs_put_delayed_ref(&head->node);
 883                                 goto again;
 884                         }
 885                         ret = __add_delayed_refs(head, time_seq,
 886                                                  &prefs_delayed);
 887                         mutex_unlock(&head->mutex);
 888                         if (ret) {
 889                                 spin_unlock(&delayed_refs->lock);
 890                                 goto out;
 891                         }
 892                 }
 893                 spin_unlock(&delayed_refs->lock);
 894         }
 895
 896         if (path->slots[0]) {
 897                 struct extent_buffer *leaf;
 898                 int slot;
 899
 900                 path->slots[0]--;
 901                 leaf = path->nodes[0];
 902                 slot = path->slots[0];
 903                 btrfs_item_key_to_cpu(leaf, &key, slot);
 904                 if (key.objectid == bytenr &&
 905                     (key.type == BTRFS_EXTENT_ITEM_KEY ||
 906                      key.type == BTRFS_METADATA_ITEM_KEY)) {
 907                         ret = __add_inline_refs(fs_info, path, bytenr,
 908                                                 &info_level, &prefs);
 909                         if (ret)
 910                                 goto out;
 911                         ret = __add_keyed_refs(fs_info, path, bytenr,
 912                                                info_level, &prefs);
 913                         if (ret)
 914                                 goto out;
 915                 }
 916         }
 917         btrfs_release_path(path);
 918
 919         list_splice_init(&prefs_delayed, &prefs);
 920
 921         ret = __add_missing_keys(fs_info, &prefs);
 922         if (ret)
 923                 goto out;
 924
 925         __merge_refs(&prefs, 1);
 926
 927         ret = __resolve_indirect_refs(fs_info, path, time_seq, &prefs,
 928                                       extent_item_pos);
 929         if (ret)
 930                 goto out;
 931
 932         __merge_refs(&prefs, 2);
 933
 934         while (!list_empty(&prefs)) {
 935                 ref = list_first_entry(&prefs, struct __prelim_ref, list);
 936                 WARN_ON(ref->count < 0);
 937                 if (ref->count && ref->root_id && ref->parent == 0) {
 938                         /* no parent == root of tree */
 939                         ret = ulist_add(roots, ref->root_id, 0, GFP_NOFS);
 940                         if (ret < 0)
 941                                 goto out;
 942                 }
 943                 if (ref->count && ref->parent) {
 944                         struct extent_inode_elem *eie = NULL;
 945                         if (extent_item_pos && !ref->inode_list) {
 946                                 u32 bsz;
 947                                 struct extent_buffer *eb;
 948                                 bsz = btrfs_level_size(fs_info->extent_root,
 949                                                         info_level);
 950                                 eb = read_tree_block(fs_info->extent_root,
 951                                                            ref->parent, bsz, 0);
 952                                 if (!eb || !extent_buffer_uptodate(eb)) {
 953                                         free_extent_buffer(eb);
 954                                         ret = -EIO;
 955                                         goto out;
 956                                 }
 957                                 ret = find_extent_in_eb(eb, bytenr,
 958                                                         *extent_item_pos, &eie);
 959                                 free_extent_buffer(eb);
 960                                 if (ret < 0)
 961                                         goto out;
 962                                 ref->inode_list = eie;
 963                         }
 964                         ret = ulist_add_merge(refs, ref->parent,
 965                                               (uintptr_t)ref->inode_list,
 966                                               (u64 *)&eie, GFP_NOFS);
 967                         if (ret < 0)
 968                                 goto out;
 969                         if (!ret && extent_item_pos) {
 970                                 /*
 971                                  * we've recorded that parent, so we must extend
 972                                  * its inode list here
 973                                  */
 974                                 BUG_ON(!eie);
 975                                 while (eie->next)
 976                                         eie = eie->next;
 977                                 eie->next = ref->inode_list;
 978                         }
 979                 }
 980                 list_del(&ref->list);
 981                 kmem_cache_free(btrfs_prelim_ref_cache, ref);
 982         }
 983
 984 out:
 985         btrfs_free_path(path);
 986         while (!list_empty(&prefs)) {
 987                 ref = list_first_entry(&prefs, struct __prelim_ref, list);
 988                 list_del(&ref->list);
 989                 kmem_cache_free(btrfs_prelim_ref_cache, ref);
 990         }
 991         while (!list_empty(&prefs_delayed)) {
 992                 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
 993                                        list);
 994                 list_del(&ref->list);
 995                 kmem_cache_free(btrfs_prelim_ref_cache, ref);
 996         }
 997
 998         return ret;
 999 }
1000
1001 static void free_leaf_list(struct ulist *blocks)
1002 {
1003         struct ulist_node *node = NULL;
1004         struct extent_inode_elem *eie;
1005         struct extent_inode_elem *eie_next;
1006         struct ulist_iterator uiter;
1007
1008         ULIST_ITER_INIT(&uiter);
1009         while ((node = ulist_next(blocks, &uiter))) {
1010                 if (!node->aux)
1011                         continue;
1012                 eie = (struct extent_inode_elem *)(uintptr_t)node->aux;
1013                 for (; eie; eie = eie_next) {
1014                         eie_next = eie->next;
1015                         kfree(eie);
1016                 }
1017                 node->aux = 0;
1018         }
1019
1020         ulist_free(blocks);
1021 }
1022
1023 /*
1024  * Finds all leafs with a reference to the specified combination of bytenr and
1025  * offset. key_list_head will point to a list of corresponding keys (caller must
1026  * free each list element). The leafs will be stored in the leafs ulist, which
1027  * must be freed with ulist_free.
1028  *
1029  * returns 0 on success, <0 on error
1030  */
1031 static int btrfs_find_all_leafs(struct btrfs_trans_handle *trans,
1032                                 struct btrfs_fs_info *fs_info, u64 bytenr,
1033                                 u64 time_seq, struct ulist **leafs,
1034                                 const u64 *extent_item_pos)
1035 {
1036         struct ulist *tmp;
1037         int ret;
1038
1039         tmp = ulist_alloc(GFP_NOFS);
1040         if (!tmp)
1041                 return -ENOMEM;
1042         *leafs = ulist_alloc(GFP_NOFS);
1043         if (!*leafs) {
1044                 ulist_free(tmp);
1045                 return -ENOMEM;
1046         }
1047
1048         ret = find_parent_nodes(trans, fs_info, bytenr,
1049                                 time_seq, *leafs, tmp, extent_item_pos);
1050         ulist_free(tmp);
1051
1052         if (ret < 0 && ret != -ENOENT) {
1053                 free_leaf_list(*leafs);
1054                 return ret;
1055         }
1056
1057         return 0;
1058 }
1059
1060 /*
1061  * walk all backrefs for a given extent to find all roots that reference this
1062  * extent. Walking a backref means finding all extents that reference this
1063  * extent and in turn walk the backrefs of those, too. Naturally this is a
1064  * recursive process, but here it is implemented in an iterative fashion: We
1065  * find all referencing extents for the extent in question and put them on a
1066  * list. In turn, we find all referencing extents for those, further appending
1067  * to the list. The way we iterate the list allows adding more elements after
1068  * the current while iterating. The process stops when we reach the end of the
1069  * list. Found roots are added to the roots list.
1070  *
1071  * returns 0 on success, < 0 on error.
1072  */
1073 int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
1074                                 struct btrfs_fs_info *fs_info, u64 bytenr,
1075                                 u64 time_seq, struct ulist **roots)
1076 {
1077         struct ulist *tmp;
1078         struct ulist_node *node = NULL;
1079         struct ulist_iterator uiter;
1080         int ret;
1081
1082         tmp = ulist_alloc(GFP_NOFS);
1083         if (!tmp)
1084                 return -ENOMEM;
1085         *roots = ulist_alloc(GFP_NOFS);
1086         if (!*roots) {
1087                 ulist_free(tmp);
1088                 return -ENOMEM;
1089         }
1090
1091         ULIST_ITER_INIT(&uiter);
1092         while (1) {
1093                 ret = find_parent_nodes(trans, fs_info, bytenr,
1094                                         time_seq, tmp, *roots, NULL);
1095                 if (ret < 0 && ret != -ENOENT) {
1096                         ulist_free(tmp);
1097                         ulist_free(*roots);
1098                         return ret;
1099                 }
1100                 node = ulist_next(tmp, &uiter);
1101                 if (!node)
1102                         break;
1103                 bytenr = node->val;
1104         }
1105
1106         ulist_free(tmp);
1107         return 0;
1108 }
1109
1110
1111 static int __inode_info(u64 inum, u64 ioff, u8 key_type,
1112                         struct btrfs_root *fs_root, struct btrfs_path *path,
1113                         struct btrfs_key *found_key)
1114 {
1115         int ret;
1116         struct btrfs_key key;
1117         struct extent_buffer *eb;
1118
1119         key.type = key_type;
1120         key.objectid = inum;
1121         key.offset = ioff;
1122
1123         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1124         if (ret < 0)
1125                 return ret;
1126
1127         eb = path->nodes[0];
1128         if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1129                 ret = btrfs_next_leaf(fs_root, path);
1130                 if (ret)
1131                         return ret;
1132                 eb = path->nodes[0];
1133         }
1134
1135         btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1136         if (found_key->type != key.type || found_key->objectid != key.objectid)
1137                 return 1;
1138
1139         return 0;
1140 }
1141
1142 /*
1143  * this makes the path point to (inum INODE_ITEM ioff)
1144  */
1145 int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1146                         struct btrfs_path *path)
1147 {
1148         struct btrfs_key key;
1149         return __inode_info(inum, ioff, BTRFS_INODE_ITEM_KEY, fs_root, path,
1150                                 &key);
1151 }
1152
1153 static int inode_ref_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
1154                                 struct btrfs_path *path,
1155                                 struct btrfs_key *found_key)
1156 {
1157         return __inode_info(inum, ioff, BTRFS_INODE_REF_KEY, fs_root, path,
1158                                 found_key);
1159 }
1160
1161 int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
1162                           u64 start_off, struct btrfs_path *path,
1163                           struct btrfs_inode_extref **ret_extref,
1164                           u64 *found_off)
1165 {
1166         int ret, slot;
1167         struct btrfs_key key;
1168         struct btrfs_key found_key;
1169         struct btrfs_inode_extref *extref;
1170         struct extent_buffer *leaf;
1171         unsigned long ptr;
1172
1173         key.objectid = inode_objectid;
1174         btrfs_set_key_type(&key, BTRFS_INODE_EXTREF_KEY);
1175         key.offset = start_off;
1176
1177         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1178         if (ret < 0)
1179                 return ret;
1180
1181         while (1) {
1182                 leaf = path->nodes[0];
1183                 slot = path->slots[0];
1184                 if (slot >= btrfs_header_nritems(leaf)) {
1185                         /*
1186                          * If the item at offset is not found,
1187                          * btrfs_search_slot will point us to the slot
1188                          * where it should be inserted. In our case
1189                          * that will be the slot directly before the
1190                          * next INODE_REF_KEY_V2 item. In the case
1191                          * that we're pointing to the last slot in a
1192                          * leaf, we must move one leaf over.
1193                          */
1194                         ret = btrfs_next_leaf(root, path);
1195                         if (ret) {
1196                                 if (ret >= 1)
1197                                         ret = -ENOENT;
1198                                 break;
1199                         }
1200                         continue;
1201                 }
1202
1203                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
1204
1205                 /*
1206                  * Check that we're still looking at an extended ref key for
1207                  * this particular objectid. If we have different
1208                  * objectid or type then there are no more to be found
1209                  * in the tree and we can exit.
1210                  */
1211                 ret = -ENOENT;
1212                 if (found_key.objectid != inode_objectid)
1213                         break;
1214                 if (btrfs_key_type(&found_key) != BTRFS_INODE_EXTREF_KEY)
1215                         break;
1216
1217                 ret = 0;
1218                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1219                 extref = (struct btrfs_inode_extref *)ptr;
1220                 *ret_extref = extref;
1221                 if (found_off)
1222                         *found_off = found_key.offset;
1223                 break;
1224         }
1225
1226         return ret;
1227 }
1228
1229 /*
1230  * this iterates to turn a name (from iref/extref) into a full filesystem path.
1231  * Elements of the path are separated by '/' and the path is guaranteed to be
1232  * 0-terminated. the path is only given within the current file system.
1233  * Therefore, it never starts with a '/'. the caller is responsible to provide
1234  * "size" bytes in "dest". the dest buffer will be filled backwards. finally,
1235  * the start point of the resulting string is returned. this pointer is within
1236  * dest, normally.
1237  * in case the path buffer would overflow, the pointer is decremented further
1238  * as if output was written to the buffer, though no more output is actually
1239  * generated. that way, the caller can determine how much space would be
1240  * required for the path to fit into the buffer. in that case, the returned
1241  * value will be smaller than dest. callers must check this!
1242  */
1243 char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
1244                         u32 name_len, unsigned long name_off,
1245                         struct extent_buffer *eb_in, u64 parent,
1246                         char *dest, u32 size)
1247 {
1248         int slot;
1249         u64 next_inum;
1250         int ret;
1251         s64 bytes_left = ((s64)size) - 1;
1252         struct extent_buffer *eb = eb_in;
1253         struct btrfs_key found_key;
1254         int leave_spinning = path->leave_spinning;
1255         struct btrfs_inode_ref *iref;
1256
1257         if (bytes_left >= 0)
1258                 dest[bytes_left] = '\0';
1259
1260         path->leave_spinning = 1;
1261         while (1) {
1262                 bytes_left -= name_len;
1263                 if (bytes_left >= 0)
1264                         read_extent_buffer(eb, dest + bytes_left,
1265                                            name_off, name_len);
1266                 if (eb != eb_in) {
1267                         btrfs_tree_read_unlock_blocking(eb);
1268                         free_extent_buffer(eb);
1269                 }
1270                 ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
1271                 if (ret > 0)
1272                         ret = -ENOENT;
1273                 if (ret)
1274                         break;
1275
1276                 next_inum = found_key.offset;
1277
1278                 /* regular exit ahead */
1279                 if (parent == next_inum)
1280                         break;
1281
1282                 slot = path->slots[0];
1283                 eb = path->nodes[0];
1284                 /* make sure we can use eb after releasing the path */
1285                 if (eb != eb_in) {
1286                         atomic_inc(&eb->refs);
1287                         btrfs_tree_read_lock(eb);
1288                         btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1289                 }
1290                 btrfs_release_path(path);
1291                 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1292
1293                 name_len = btrfs_inode_ref_name_len(eb, iref);
1294                 name_off = (unsigned long)(iref + 1);
1295
1296                 parent = next_inum;
1297                 --bytes_left;
1298                 if (bytes_left >= 0)
1299                         dest[bytes_left] = '/';
1300         }
1301
1302         btrfs_release_path(path);
1303         path->leave_spinning = leave_spinning;
1304
1305         if (ret)
1306                 return ERR_PTR(ret);
1307
1308         return dest + bytes_left;
1309 }
1310
1311 /*
1312  * this makes the path point to (logical EXTENT_ITEM *)
1313  * returns BTRFS_EXTENT_FLAG_DATA for data, BTRFS_EXTENT_FLAG_TREE_BLOCK for
1314  * tree blocks and <0 on error.
1315  */
1316 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
1317                         struct btrfs_path *path, struct btrfs_key *found_key,
1318                         u64 *flags_ret)
1319 {
1320         int ret;
1321         u64 flags;
1322         u64 size = 0;
1323         u32 item_size;
1324         struct extent_buffer *eb;
1325         struct btrfs_extent_item *ei;
1326         struct btrfs_key key;
1327
1328         if (btrfs_fs_incompat(fs_info, SKINNY_METADATA))
1329                 key.type = BTRFS_METADATA_ITEM_KEY;
1330         else
1331                 key.type = BTRFS_EXTENT_ITEM_KEY;
1332         key.objectid = logical;
1333         key.offset = (u64)-1;
1334
1335         ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path, 0, 0);
1336         if (ret < 0)
1337                 return ret;
1338         ret = btrfs_previous_item(fs_info->extent_root, path,
1339                                         0, BTRFS_EXTENT_ITEM_KEY);
1340         if (ret < 0)
1341                 return ret;
1342
1343         btrfs_item_key_to_cpu(path->nodes[0], found_key, path->slots[0]);
1344         if (found_key->type == BTRFS_METADATA_ITEM_KEY)
1345                 size = fs_info->extent_root->leafsize;
1346         else if (found_key->type == BTRFS_EXTENT_ITEM_KEY)
1347                 size = found_key->offset;
1348
1349         if ((found_key->type != BTRFS_EXTENT_ITEM_KEY &&
1350              found_key->type != BTRFS_METADATA_ITEM_KEY) ||
1351             found_key->objectid > logical ||
1352             found_key->objectid + size <= logical) {
1353                 pr_debug("logical %llu is not within any extent\n", logical);
1354                 return -ENOENT;
1355         }
1356
1357         eb = path->nodes[0];
1358         item_size = btrfs_item_size_nr(eb, path->slots[0]);
1359         BUG_ON(item_size < sizeof(*ei));
1360
1361         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
1362         flags = btrfs_extent_flags(eb, ei);
1363
1364         pr_debug("logical %llu is at position %llu within the extent (%llu "
1365                  "EXTENT_ITEM %llu) flags %#llx size %u\n",
1366                  logical, logical - found_key->objectid, found_key->objectid,
1367                  found_key->offset, flags, item_size);
1368
1369         WARN_ON(!flags_ret);
1370         if (flags_ret) {
1371                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1372                         *flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
1373                 else if (flags & BTRFS_EXTENT_FLAG_DATA)
1374                         *flags_ret = BTRFS_EXTENT_FLAG_DATA;
1375                 else
1376                         BUG_ON(1);
1377                 return 0;
1378         }
1379
1380         return -EIO;
1381 }
1382
1383 /*
1384  * helper function to iterate extent inline refs. ptr must point to a 0 value
1385  * for the first call and may be modified. it is used to track state.
1386  * if more refs exist, 0 is returned and the next call to
1387  * __get_extent_inline_ref must pass the modified ptr parameter to get the
1388  * next ref. after the last ref was processed, 1 is returned.
1389  * returns <0 on error
1390  */
1391 static int __get_extent_inline_ref(unsigned long *ptr, struct extent_buffer *eb,
1392                                 struct btrfs_extent_item *ei, u32 item_size,
1393                                 struct btrfs_extent_inline_ref **out_eiref,
1394                                 int *out_type)
1395 {
1396         unsigned long end;
1397         u64 flags;
1398         struct btrfs_tree_block_info *info;
1399
1400         if (!*ptr) {
1401                 /* first call */
1402                 flags = btrfs_extent_flags(eb, ei);
1403                 if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1404                         info = (struct btrfs_tree_block_info *)(ei + 1);
1405                         *out_eiref =
1406                                 (struct btrfs_extent_inline_ref *)(info + 1);
1407                 } else {
1408                         *out_eiref = (struct btrfs_extent_inline_ref *)(ei + 1);
1409                 }
1410                 *ptr = (unsigned long)*out_eiref;
1411                 if ((void *)*ptr >= (void *)ei + item_size)
1412                         return -ENOENT;
1413         }
1414
1415         end = (unsigned long)ei + item_size;
1416         *out_eiref = (struct btrfs_extent_inline_ref *)*ptr;
1417         *out_type = btrfs_extent_inline_ref_type(eb, *out_eiref);
1418
1419         *ptr += btrfs_extent_inline_ref_size(*out_type);
1420         WARN_ON(*ptr > end);
1421         if (*ptr == end)
1422                 return 1; /* last */
1423
1424         return 0;
1425 }
1426
1427 /*
1428  * reads the tree block backref for an extent. tree level and root are returned
1429  * through out_level and out_root. ptr must point to a 0 value for the first
1430  * call and may be modified (see __get_extent_inline_ref comment).
1431  * returns 0 if data was provided, 1 if there was no more data to provide or
1432  * <0 on error.
1433  */
1434 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
1435                                 struct btrfs_extent_item *ei, u32 item_size,
1436                                 u64 *out_root, u8 *out_level)
1437 {
1438         int ret;
1439         int type;
1440         struct btrfs_tree_block_info *info;
1441         struct btrfs_extent_inline_ref *eiref;
1442
1443         if (*ptr == (unsigned long)-1)
1444                 return 1;
1445
1446         while (1) {
1447                 ret = __get_extent_inline_ref(ptr, eb, ei, item_size,
1448                                                 &eiref, &type);
1449                 if (ret < 0)
1450                         return ret;
1451
1452                 if (type == BTRFS_TREE_BLOCK_REF_KEY ||
1453                     type == BTRFS_SHARED_BLOCK_REF_KEY)
1454                         break;
1455
1456                 if (ret == 1)
1457                         return 1;
1458         }
1459
1460         /* we can treat both ref types equally here */
1461         info = (struct btrfs_tree_block_info *)(ei + 1);
1462         *out_root = btrfs_extent_inline_ref_offset(eb, eiref);
1463         *out_level = btrfs_tree_block_level(eb, info);
1464
1465         if (ret == 1)
1466                 *ptr = (unsigned long)-1;
1467
1468         return 0;
1469 }
1470
1471 static int iterate_leaf_refs(struct extent_inode_elem *inode_list,
1472                                 u64 root, u64 extent_item_objectid,
1473                                 iterate_extent_inodes_t *iterate, void *ctx)
1474 {
1475         struct extent_inode_elem *eie;
1476         int ret = 0;
1477
1478         for (eie = inode_list; eie; eie = eie->next) {
1479                 pr_debug("ref for %llu resolved, key (%llu EXTEND_DATA %llu), "
1480                          "root %llu\n", extent_item_objectid,
1481                          eie->inum, eie->offset, root);
1482                 ret = iterate(eie->inum, eie->offset, root, ctx);
1483                 if (ret) {
1484                         pr_debug("stopping iteration for %llu due to ret=%d\n",
1485                                  extent_item_objectid, ret);
1486                         break;
1487                 }
1488         }
1489
1490         return ret;
1491 }
1492
1493 /*
1494  * calls iterate() for every inode that references the extent identified by
1495  * the given parameters.
1496  * when the iterator function returns a non-zero value, iteration stops.
1497  */
1498 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
1499                                 u64 extent_item_objectid, u64 extent_item_pos,
1500                                 int search_commit_root,
1501                                 iterate_extent_inodes_t *iterate, void *ctx)
1502 {
1503         int ret;
1504         struct btrfs_trans_handle *trans = NULL;
1505         struct ulist *refs = NULL;
1506         struct ulist *roots = NULL;
1507         struct ulist_node *ref_node = NULL;
1508         struct ulist_node *root_node = NULL;
1509         struct seq_list tree_mod_seq_elem = {};
1510         struct ulist_iterator ref_uiter;
1511         struct ulist_iterator root_uiter;
1512
1513         pr_debug("resolving all inodes for extent %llu\n",
1514                         extent_item_objectid);
1515
1516         if (!search_commit_root) {
1517                 trans = btrfs_join_transaction(fs_info->extent_root);
1518                 if (IS_ERR(trans))
1519                         return PTR_ERR(trans);
1520                 btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1521         }
1522
1523         ret = btrfs_find_all_leafs(trans, fs_info, extent_item_objectid,
1524                                    tree_mod_seq_elem.seq, &refs,
1525                                    &extent_item_pos);
1526         if (ret)
1527                 goto out;
1528
1529         ULIST_ITER_INIT(&ref_uiter);
1530         while (!ret && (ref_node = ulist_next(refs, &ref_uiter))) {
1531                 ret = btrfs_find_all_roots(trans, fs_info, ref_node->val,
1532                                            tree_mod_seq_elem.seq, &roots);
1533                 if (ret)
1534                         break;
1535                 ULIST_ITER_INIT(&root_uiter);
1536                 while (!ret && (root_node = ulist_next(roots, &root_uiter))) {
1537                         pr_debug("root %llu references leaf %llu, data list "
1538                                  "%#llx\n", root_node->val, ref_node->val,
1539                                  ref_node->aux);
1540                         ret = iterate_leaf_refs((struct extent_inode_elem *)
1541                                                 (uintptr_t)ref_node->aux,
1542                                                 root_node->val,
1543                                                 extent_item_objectid,
1544                                                 iterate, ctx);
1545                 }
1546                 ulist_free(roots);
1547         }
1548
1549         free_leaf_list(refs);
1550 out:
1551         if (!search_commit_root) {
1552                 btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
1553                 btrfs_end_transaction(trans, fs_info->extent_root);
1554         }
1555
1556         return ret;
1557 }
1558
1559 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
1560                                 struct btrfs_path *path,
1561                                 iterate_extent_inodes_t *iterate, void *ctx)
1562 {
1563         int ret;
1564         u64 extent_item_pos;
1565         u64 flags = 0;
1566         struct btrfs_key found_key;
1567         int search_commit_root = path->search_commit_root;
1568
1569         ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
1570         btrfs_release_path(path);
1571         if (ret < 0)
1572                 return ret;
1573         if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1574                 return -EINVAL;
1575
1576         extent_item_pos = logical - found_key.objectid;
1577         ret = iterate_extent_inodes(fs_info, found_key.objectid,
1578                                         extent_item_pos, search_commit_root,
1579                                         iterate, ctx);
1580
1581         return ret;
1582 }
1583
1584 typedef int (iterate_irefs_t)(u64 parent, u32 name_len, unsigned long name_off,
1585                               struct extent_buffer *eb, void *ctx);
1586
1587 static int iterate_inode_refs(u64 inum, struct btrfs_root *fs_root,
1588                               struct btrfs_path *path,
1589                               iterate_irefs_t *iterate, void *ctx)
1590 {
1591         int ret = 0;
1592         int slot;
1593         u32 cur;
1594         u32 len;
1595         u32 name_len;
1596         u64 parent = 0;
1597         int found = 0;
1598         struct extent_buffer *eb;
1599         struct btrfs_item *item;
1600         struct btrfs_inode_ref *iref;
1601         struct btrfs_key found_key;
1602
1603         while (!ret) {
1604                 path->leave_spinning = 1;
1605                 ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
1606                                      &found_key);
1607                 if (ret < 0)
1608                         break;
1609                 if (ret) {
1610                         ret = found ? 0 : -ENOENT;
1611                         break;
1612                 }
1613                 ++found;
1614
1615                 parent = found_key.offset;
1616                 slot = path->slots[0];
1617                 eb = path->nodes[0];
1618                 /* make sure we can use eb after releasing the path */
1619                 atomic_inc(&eb->refs);
1620                 btrfs_tree_read_lock(eb);
1621                 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1622                 btrfs_release_path(path);
1623
1624                 item = btrfs_item_nr(slot);
1625                 iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
1626
1627                 for (cur = 0; cur < btrfs_item_size(eb, item); cur += len) {
1628                         name_len = btrfs_inode_ref_name_len(eb, iref);
1629                         /* path must be released before calling iterate()! */
1630                         pr_debug("following ref at offset %u for inode %llu in "
1631                                  "tree %llu\n", cur, found_key.objectid,
1632                                  fs_root->objectid);
1633                         ret = iterate(parent, name_len,
1634                                       (unsigned long)(iref + 1), eb, ctx);
1635                         if (ret)
1636                                 break;
1637                         len = sizeof(*iref) + name_len;
1638                         iref = (struct btrfs_inode_ref *)((char *)iref + len);
1639                 }
1640                 btrfs_tree_read_unlock_blocking(eb);
1641                 free_extent_buffer(eb);
1642         }
1643
1644         btrfs_release_path(path);
1645
1646         return ret;
1647 }
1648
1649 static int iterate_inode_extrefs(u64 inum, struct btrfs_root *fs_root,
1650                                  struct btrfs_path *path,
1651                                  iterate_irefs_t *iterate, void *ctx)
1652 {
1653         int ret;
1654         int slot;
1655         u64 offset = 0;
1656         u64 parent;
1657         int found = 0;
1658         struct extent_buffer *eb;
1659         struct btrfs_inode_extref *extref;
1660         struct extent_buffer *leaf;
1661         u32 item_size;
1662         u32 cur_offset;
1663         unsigned long ptr;
1664
1665         while (1) {
1666                 ret = btrfs_find_one_extref(fs_root, inum, offset, path, &extref,
1667                                             &offset);
1668                 if (ret < 0)
1669                         break;
1670                 if (ret) {
1671                         ret = found ? 0 : -ENOENT;
1672                         break;
1673                 }
1674                 ++found;
1675
1676                 slot = path->slots[0];
1677                 eb = path->nodes[0];
1678                 /* make sure we can use eb after releasing the path */
1679                 atomic_inc(&eb->refs);
1680
1681                 btrfs_tree_read_lock(eb);
1682                 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1683                 btrfs_release_path(path);
1684
1685                 leaf = path->nodes[0];
1686                 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
1687                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
1688                 cur_offset = 0;
1689
1690                 while (cur_offset < item_size) {
1691                         u32 name_len;
1692
1693                         extref = (struct btrfs_inode_extref *)(ptr + cur_offset);
1694                         parent = btrfs_inode_extref_parent(eb, extref);
1695                         name_len = btrfs_inode_extref_name_len(eb, extref);
1696                         ret = iterate(parent, name_len,
1697                                       (unsigned long)&extref->name, eb, ctx);
1698                         if (ret)
1699                                 break;
1700
1701                         cur_offset += btrfs_inode_extref_name_len(leaf, extref);
1702                         cur_offset += sizeof(*extref);
1703                 }
1704                 btrfs_tree_read_unlock_blocking(eb);
1705                 free_extent_buffer(eb);
1706
1707                 offset++;
1708         }
1709
1710         btrfs_release_path(path);
1711
1712         return ret;
1713 }
1714
1715 static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
1716                          struct btrfs_path *path, iterate_irefs_t *iterate,
1717                          void *ctx)
1718 {
1719         int ret;
1720         int found_refs = 0;
1721
1722         ret = iterate_inode_refs(inum, fs_root, path, iterate, ctx);
1723         if (!ret)
1724                 ++found_refs;
1725         else if (ret != -ENOENT)
1726                 return ret;
1727
1728         ret = iterate_inode_extrefs(inum, fs_root, path, iterate, ctx);
1729         if (ret == -ENOENT && found_refs)
1730                 return 0;
1731
1732         return ret;
1733 }
1734
1735 /*
1736  * returns 0 if the path could be dumped (probably truncated)
1737  * returns <0 in case of an error
1738  */
1739 static int inode_to_path(u64 inum, u32 name_len, unsigned long name_off,
1740                          struct extent_buffer *eb, void *ctx)
1741 {
1742         struct inode_fs_paths *ipath = ctx;
1743         char *fspath;
1744         char *fspath_min;
1745         int i = ipath->fspath->elem_cnt;
1746         const int s_ptr = sizeof(char *);
1747         u32 bytes_left;
1748
1749         bytes_left = ipath->fspath->bytes_left > s_ptr ?
1750                                         ipath->fspath->bytes_left - s_ptr : 0;
1751
1752         fspath_min = (char *)ipath->fspath->val + (i + 1) * s_ptr;
1753         fspath = btrfs_ref_to_path(ipath->fs_root, ipath->btrfs_path, name_len,
1754                                    name_off, eb, inum, fspath_min, bytes_left);
1755         if (IS_ERR(fspath))
1756                 return PTR_ERR(fspath);
1757
1758         if (fspath > fspath_min) {
1759                 ipath->fspath->val[i] = (u64)(unsigned long)fspath;
1760                 ++ipath->fspath->elem_cnt;
1761                 ipath->fspath->bytes_left = fspath - fspath_min;
1762         } else {
1763                 ++ipath->fspath->elem_missed;
1764                 ipath->fspath->bytes_missing += fspath_min - fspath;
1765                 ipath->fspath->bytes_left = 0;
1766         }
1767
1768         return 0;
1769 }
1770
1771 /*
1772  * this dumps all file system paths to the inode into the ipath struct, provided
1773  * is has been created large enough. each path is zero-terminated and accessed
1774  * from ipath->fspath->val[i].
1775  * when it returns, there are ipath->fspath->elem_cnt number of paths available
1776  * in ipath->fspath->val[]. when the allocated space wasn't sufficient, the
1777  * number of missed paths in recored in ipath->fspath->elem_missed, otherwise,
1778  * it's zero. ipath->fspath->bytes_missing holds the number of bytes that would
1779  * have been needed to return all paths.
1780  */
1781 int paths_from_inode(u64 inum, struct inode_fs_paths *ipath)
1782 {
1783         return iterate_irefs(inum, ipath->fs_root, ipath->btrfs_path,
1784                              inode_to_path, ipath);
1785 }
1786
1787 struct btrfs_data_container *init_data_container(u32 total_bytes)
1788 {
1789         struct btrfs_data_container *data;
1790         size_t alloc_bytes;
1791
1792         alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
1793         data = vmalloc(alloc_bytes);
1794         if (!data)
1795                 return ERR_PTR(-ENOMEM);
1796
1797         if (total_bytes >= sizeof(*data)) {
1798                 data->bytes_left = total_bytes - sizeof(*data);
1799                 data->bytes_missing = 0;
1800         } else {
1801                 data->bytes_missing = sizeof(*data) - total_bytes;
1802                 data->bytes_left = 0;
1803         }
1804
1805         data->elem_cnt = 0;
1806         data->elem_missed = 0;
1807
1808         return data;
1809 }
1810
1811 /*
1812  * allocates space to return multiple file system paths for an inode.
1813  * total_bytes to allocate are passed, note that space usable for actual path
1814  * information will be total_bytes - sizeof(struct inode_fs_paths).
1815  * the returned pointer must be freed with free_ipath() in the end.
1816  */
1817 struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
1818                                         struct btrfs_path *path)
1819 {
1820         struct inode_fs_paths *ifp;
1821         struct btrfs_data_container *fspath;
1822
1823         fspath = init_data_container(total_bytes);
1824         if (IS_ERR(fspath))
1825                 return (void *)fspath;
1826
1827         ifp = kmalloc(sizeof(*ifp), GFP_NOFS);
1828         if (!ifp) {
1829                 kfree(fspath);
1830                 return ERR_PTR(-ENOMEM);
1831         }
1832
1833         ifp->btrfs_path = path;
1834         ifp->fspath = fspath;
1835         ifp->fs_root = fs_root;
1836
1837         return ifp;
1838 }
1839
1840 void free_ipath(struct inode_fs_paths *ipath)
1841 {
1842         if (!ipath)
1843                 return;
1844         vfree(ipath->fspath);
1845         kfree(ipath);
1846 }