fs/btrfs/ref-verify.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2014 Facebook.  All rights reserved.
   4  */
   5
   6 #include <linux/sched.h>
   7 #include <linux/stacktrace.h>
   8 #include "ctree.h"
   9 #include "disk-io.h"
  10 #include "locking.h"
  11 #include "delayed-ref.h"
  12 #include "ref-verify.h"
  13
  14 /*
  15  * Used to keep track the roots and number of refs each root has for a given
  16  * bytenr.  This just tracks the number of direct references, no shared
  17  * references.
  18  */
  19 struct root_entry {
  20         u64 root_objectid;
  21         u64 num_refs;
  22         struct rb_node node;
  23 };
  24
  25 /*
  26  * These are meant to represent what should exist in the extent tree, these can
  27  * be used to verify the extent tree is consistent as these should all match
  28  * what the extent tree says.
  29  */
  30 struct ref_entry {
  31         u64 root_objectid;
  32         u64 parent;
  33         u64 owner;
  34         u64 offset;
  35         u64 num_refs;
  36         struct rb_node node;
  37 };
  38
  39 #define MAX_TRACE       16
  40
  41 /*
  42  * Whenever we add/remove a reference we record the action.  The action maps
  43  * back to the delayed ref action.  We hold the ref we are changing in the
  44  * action so we can account for the history properly, and we record the root we
  45  * were called with since it could be different from ref_root.  We also store
  46  * stack traces because that's how I roll.
  47  */
  48 struct ref_action {
  49         int action;
  50         u64 root;
  51         struct ref_entry ref;
  52         struct list_head list;
  53         unsigned long trace[MAX_TRACE];
  54         unsigned int trace_len;
  55 };
  56
  57 /*
  58  * One of these for every block we reference, it holds the roots and references
  59  * to it as well as all of the ref actions that have occurred to it.  We never
  60  * free it until we unmount the file system in order to make sure re-allocations
  61  * are happening properly.
  62  */
  63 struct block_entry {
  64         u64 bytenr;
  65         u64 len;
  66         u64 num_refs;
  67         int metadata;
  68         int from_disk;
  69         struct rb_root roots;
  70         struct rb_root refs;
  71         struct rb_node node;
  72         struct list_head actions;
  73 };
  74
  75 static struct block_entry *insert_block_entry(struct rb_root *root,
  76                                               struct block_entry *be)
  77 {
  78         struct rb_node **p = &root->rb_node;
  79         struct rb_node *parent_node = NULL;
  80         struct block_entry *entry;
  81
  82         while (*p) {
  83                 parent_node = *p;
  84                 entry = rb_entry(parent_node, struct block_entry, node);
  85                 if (entry->bytenr > be->bytenr)
  86                         p = &(*p)->rb_left;
  87                 else if (entry->bytenr < be->bytenr)
  88                         p = &(*p)->rb_right;
  89                 else
  90                         return entry;
  91         }
  92
  93         rb_link_node(&be->node, parent_node, p);
  94         rb_insert_color(&be->node, root);
  95         return NULL;
  96 }
  97
  98 static struct block_entry *lookup_block_entry(struct rb_root *root, u64 bytenr)
  99 {
 100         struct rb_node *n;
 101         struct block_entry *entry = NULL;
 102
 103         n = root->rb_node;
 104         while (n) {
 105                 entry = rb_entry(n, struct block_entry, node);
 106                 if (entry->bytenr < bytenr)
 107                         n = n->rb_right;
 108                 else if (entry->bytenr > bytenr)
 109                         n = n->rb_left;
 110                 else
 111                         return entry;
 112         }
 113         return NULL;
 114 }
 115
 116 static struct root_entry *insert_root_entry(struct rb_root *root,
 117                                             struct root_entry *re)
 118 {
 119         struct rb_node **p = &root->rb_node;
 120         struct rb_node *parent_node = NULL;
 121         struct root_entry *entry;
 122
 123         while (*p) {
 124                 parent_node = *p;
 125                 entry = rb_entry(parent_node, struct root_entry, node);
 126                 if (entry->root_objectid > re->root_objectid)
 127                         p = &(*p)->rb_left;
 128                 else if (entry->root_objectid < re->root_objectid)
 129                         p = &(*p)->rb_right;
 130                 else
 131                         return entry;
 132         }
 133
 134         rb_link_node(&re->node, parent_node, p);
 135         rb_insert_color(&re->node, root);
 136         return NULL;
 137
 138 }
 139
 140 static int comp_refs(struct ref_entry *ref1, struct ref_entry *ref2)
 141 {
 142         if (ref1->root_objectid < ref2->root_objectid)
 143                 return -1;
 144         if (ref1->root_objectid > ref2->root_objectid)
 145                 return 1;
 146         if (ref1->parent < ref2->parent)
 147                 return -1;
 148         if (ref1->parent > ref2->parent)
 149                 return 1;
 150         if (ref1->owner < ref2->owner)
 151                 return -1;
 152         if (ref1->owner > ref2->owner)
 153                 return 1;
 154         if (ref1->offset < ref2->offset)
 155                 return -1;
 156         if (ref1->offset > ref2->offset)
 157                 return 1;
 158         return 0;
 159 }
 160
 161 static struct ref_entry *insert_ref_entry(struct rb_root *root,
 162                                           struct ref_entry *ref)
 163 {
 164         struct rb_node **p = &root->rb_node;
 165         struct rb_node *parent_node = NULL;
 166         struct ref_entry *entry;
 167         int cmp;
 168
 169         while (*p) {
 170                 parent_node = *p;
 171                 entry = rb_entry(parent_node, struct ref_entry, node);
 172                 cmp = comp_refs(entry, ref);
 173                 if (cmp > 0)
 174                         p = &(*p)->rb_left;
 175                 else if (cmp < 0)
 176                         p = &(*p)->rb_right;
 177                 else
 178                         return entry;
 179         }
 180
 181         rb_link_node(&ref->node, parent_node, p);
 182         rb_insert_color(&ref->node, root);
 183         return NULL;
 184
 185 }
 186
 187 static struct root_entry *lookup_root_entry(struct rb_root *root, u64 objectid)
 188 {
 189         struct rb_node *n;
 190         struct root_entry *entry = NULL;
 191
 192         n = root->rb_node;
 193         while (n) {
 194                 entry = rb_entry(n, struct root_entry, node);
 195                 if (entry->root_objectid < objectid)
 196                         n = n->rb_right;
 197                 else if (entry->root_objectid > objectid)
 198                         n = n->rb_left;
 199                 else
 200                         return entry;
 201         }
 202         return NULL;
 203 }
 204
 205 #ifdef CONFIG_STACKTRACE
 206 static void __save_stack_trace(struct ref_action *ra)
 207 {
 208         ra->trace_len = stack_trace_save(ra->trace, MAX_TRACE, 2);
 209 }
 210
 211 static void __print_stack_trace(struct btrfs_fs_info *fs_info,
 212                                 struct ref_action *ra)
 213 {
 214         if (ra->trace_len == 0) {
 215                 btrfs_err(fs_info, "  ref-verify: no stacktrace");
 216                 return;
 217         }
 218         stack_trace_print(ra->trace, ra->trace_len, 2);
 219 }
 220 #else
 221 static inline void __save_stack_trace(struct ref_action *ra)
 222 {
 223 }
 224
 225 static inline void __print_stack_trace(struct btrfs_fs_info *fs_info,
 226                                        struct ref_action *ra)
 227 {
 228         btrfs_err(fs_info, "  ref-verify: no stacktrace support");
 229 }
 230 #endif
 231
 232 static void free_block_entry(struct block_entry *be)
 233 {
 234         struct root_entry *re;
 235         struct ref_entry *ref;
 236         struct ref_action *ra;
 237         struct rb_node *n;
 238
 239         while ((n = rb_first(&be->roots))) {
 240                 re = rb_entry(n, struct root_entry, node);
 241                 rb_erase(&re->node, &be->roots);
 242                 kfree(re);
 243         }
 244
 245         while((n = rb_first(&be->refs))) {
 246                 ref = rb_entry(n, struct ref_entry, node);
 247                 rb_erase(&ref->node, &be->refs);
 248                 kfree(ref);
 249         }
 250
 251         while (!list_empty(&be->actions)) {
 252                 ra = list_first_entry(&be->actions, struct ref_action,
 253                                       list);
 254                 list_del(&ra->list);
 255                 kfree(ra);
 256         }
 257         kfree(be);
 258 }
 259
 260 static struct block_entry *add_block_entry(struct btrfs_fs_info *fs_info,
 261                                            u64 bytenr, u64 len,
 262                                            u64 root_objectid)
 263 {
 264         struct block_entry *be = NULL, *exist;
 265         struct root_entry *re = NULL;
 266
 267         re = kzalloc(sizeof(struct root_entry), GFP_KERNEL);
 268         be = kzalloc(sizeof(struct block_entry), GFP_KERNEL);
 269         if (!be || !re) {
 270                 kfree(re);
 271                 kfree(be);
 272                 return ERR_PTR(-ENOMEM);
 273         }
 274         be->bytenr = bytenr;
 275         be->len = len;
 276
 277         re->root_objectid = root_objectid;
 278         re->num_refs = 0;
 279
 280         spin_lock(&fs_info->ref_verify_lock);
 281         exist = insert_block_entry(&fs_info->block_tree, be);
 282         if (exist) {
 283                 if (root_objectid) {
 284                         struct root_entry *exist_re;
 285
 286                         exist_re = insert_root_entry(&exist->roots, re);
 287                         if (exist_re)
 288                                 kfree(re);
 289                 } else {
 290                         kfree(re);
 291                 }
 292                 kfree(be);
 293                 return exist;
 294         }
 295
 296         be->num_refs = 0;
 297         be->metadata = 0;
 298         be->from_disk = 0;
 299         be->roots = RB_ROOT;
 300         be->refs = RB_ROOT;
 301         INIT_LIST_HEAD(&be->actions);
 302         if (root_objectid)
 303                 insert_root_entry(&be->roots, re);
 304         else
 305                 kfree(re);
 306         return be;
 307 }
 308
 309 static int add_tree_block(struct btrfs_fs_info *fs_info, u64 ref_root,
 310                           u64 parent, u64 bytenr, int level)
 311 {
 312         struct block_entry *be;
 313         struct root_entry *re;
 314         struct ref_entry *ref = NULL, *exist;
 315
 316         ref = kmalloc(sizeof(struct ref_entry), GFP_KERNEL);
 317         if (!ref)
 318                 return -ENOMEM;
 319
 320         if (parent)
 321                 ref->root_objectid = 0;
 322         else
 323                 ref->root_objectid = ref_root;
 324         ref->parent = parent;
 325         ref->owner = level;
 326         ref->offset = 0;
 327         ref->num_refs = 1;
 328
 329         be = add_block_entry(fs_info, bytenr, fs_info->nodesize, ref_root);
 330         if (IS_ERR(be)) {
 331                 kfree(ref);
 332                 return PTR_ERR(be);
 333         }
 334         be->num_refs++;
 335         be->from_disk = 1;
 336         be->metadata = 1;
 337
 338         if (!parent) {
 339                 ASSERT(ref_root);
 340                 re = lookup_root_entry(&be->roots, ref_root);
 341                 ASSERT(re);
 342                 re->num_refs++;
 343         }
 344         exist = insert_ref_entry(&be->refs, ref);
 345         if (exist) {
 346                 exist->num_refs++;
 347                 kfree(ref);
 348         }
 349         spin_unlock(&fs_info->ref_verify_lock);
 350
 351         return 0;
 352 }
 353
 354 static int add_shared_data_ref(struct btrfs_fs_info *fs_info,
 355                                u64 parent, u32 num_refs, u64 bytenr,
 356                                u64 num_bytes)
 357 {
 358         struct block_entry *be;
 359         struct ref_entry *ref;
 360
 361         ref = kzalloc(sizeof(struct ref_entry), GFP_KERNEL);
 362         if (!ref)
 363                 return -ENOMEM;
 364         be = add_block_entry(fs_info, bytenr, num_bytes, 0);
 365         if (IS_ERR(be)) {
 366                 kfree(ref);
 367                 return PTR_ERR(be);
 368         }
 369         be->num_refs += num_refs;
 370
 371         ref->parent = parent;
 372         ref->num_refs = num_refs;
 373         if (insert_ref_entry(&be->refs, ref)) {
 374                 spin_unlock(&fs_info->ref_verify_lock);
 375                 btrfs_err(fs_info, "existing shared ref when reading from disk?");
 376                 kfree(ref);
 377                 return -EINVAL;
 378         }
 379         spin_unlock(&fs_info->ref_verify_lock);
 380         return 0;
 381 }
 382
 383 static int add_extent_data_ref(struct btrfs_fs_info *fs_info,
 384                                struct extent_buffer *leaf,
 385                                struct btrfs_extent_data_ref *dref,
 386                                u64 bytenr, u64 num_bytes)
 387 {
 388         struct block_entry *be;
 389         struct ref_entry *ref;
 390         struct root_entry *re;
 391         u64 ref_root = btrfs_extent_data_ref_root(leaf, dref);
 392         u64 owner = btrfs_extent_data_ref_objectid(leaf, dref);
 393         u64 offset = btrfs_extent_data_ref_offset(leaf, dref);
 394         u32 num_refs = btrfs_extent_data_ref_count(leaf, dref);
 395
 396         ref = kzalloc(sizeof(struct ref_entry), GFP_KERNEL);
 397         if (!ref)
 398                 return -ENOMEM;
 399         be = add_block_entry(fs_info, bytenr, num_bytes, ref_root);
 400         if (IS_ERR(be)) {
 401                 kfree(ref);
 402                 return PTR_ERR(be);
 403         }
 404         be->num_refs += num_refs;
 405
 406         ref->parent = 0;
 407         ref->owner = owner;
 408         ref->root_objectid = ref_root;
 409         ref->offset = offset;
 410         ref->num_refs = num_refs;
 411         if (insert_ref_entry(&be->refs, ref)) {
 412                 spin_unlock(&fs_info->ref_verify_lock);
 413                 btrfs_err(fs_info, "existing ref when reading from disk?");
 414                 kfree(ref);
 415                 return -EINVAL;
 416         }
 417
 418         re = lookup_root_entry(&be->roots, ref_root);
 419         if (!re) {
 420                 spin_unlock(&fs_info->ref_verify_lock);
 421                 btrfs_err(fs_info, "missing root in new block entry?");
 422                 return -EINVAL;
 423         }
 424         re->num_refs += num_refs;
 425         spin_unlock(&fs_info->ref_verify_lock);
 426         return 0;
 427 }
 428
 429 static int process_extent_item(struct btrfs_fs_info *fs_info,
 430                                struct btrfs_path *path, struct btrfs_key *key,
 431                                int slot, int *tree_block_level)
 432 {
 433         struct btrfs_extent_item *ei;
 434         struct btrfs_extent_inline_ref *iref;
 435         struct btrfs_extent_data_ref *dref;
 436         struct btrfs_shared_data_ref *sref;
 437         struct extent_buffer *leaf = path->nodes[0];
 438         u32 item_size = btrfs_item_size_nr(leaf, slot);
 439         unsigned long end, ptr;
 440         u64 offset, flags, count;
 441         int type, ret;
 442
 443         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 444         flags = btrfs_extent_flags(leaf, ei);
 445
 446         if ((key->type == BTRFS_EXTENT_ITEM_KEY) &&
 447             flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 448                 struct btrfs_tree_block_info *info;
 449
 450                 info = (struct btrfs_tree_block_info *)(ei + 1);
 451                 *tree_block_level = btrfs_tree_block_level(leaf, info);
 452                 iref = (struct btrfs_extent_inline_ref *)(info + 1);
 453         } else {
 454                 if (key->type == BTRFS_METADATA_ITEM_KEY)
 455                         *tree_block_level = key->offset;
 456                 iref = (struct btrfs_extent_inline_ref *)(ei + 1);
 457         }
 458
 459         ptr = (unsigned long)iref;
 460         end = (unsigned long)ei + item_size;
 461         while (ptr < end) {
 462                 iref = (struct btrfs_extent_inline_ref *)ptr;
 463                 type = btrfs_extent_inline_ref_type(leaf, iref);
 464                 offset = btrfs_extent_inline_ref_offset(leaf, iref);
 465                 switch (type) {
 466                 case BTRFS_TREE_BLOCK_REF_KEY:
 467                         ret = add_tree_block(fs_info, offset, 0, key->objectid,
 468                                              *tree_block_level);
 469                         break;
 470                 case BTRFS_SHARED_BLOCK_REF_KEY:
 471                         ret = add_tree_block(fs_info, 0, offset, key->objectid,
 472                                              *tree_block_level);
 473                         break;
 474                 case BTRFS_EXTENT_DATA_REF_KEY:
 475                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
 476                         ret = add_extent_data_ref(fs_info, leaf, dref,
 477                                                   key->objectid, key->offset);
 478                         break;
 479                 case BTRFS_SHARED_DATA_REF_KEY:
 480                         sref = (struct btrfs_shared_data_ref *)(iref + 1);
 481                         count = btrfs_shared_data_ref_count(leaf, sref);
 482                         ret = add_shared_data_ref(fs_info, offset, count,
 483                                                   key->objectid, key->offset);
 484                         break;
 485                 default:
 486                         btrfs_err(fs_info, "invalid key type in iref");
 487                         ret = -EINVAL;
 488                         break;
 489                 }
 490                 if (ret)
 491                         break;
 492                 ptr += btrfs_extent_inline_ref_size(type);
 493         }
 494         return ret;
 495 }
 496
 497 static int process_leaf(struct btrfs_root *root,
 498                         struct btrfs_path *path, u64 *bytenr, u64 *num_bytes,
 499                         int *tree_block_level)
 500 {
 501         struct btrfs_fs_info *fs_info = root->fs_info;
 502         struct extent_buffer *leaf = path->nodes[0];
 503         struct btrfs_extent_data_ref *dref;
 504         struct btrfs_shared_data_ref *sref;
 505         u32 count;
 506         int i = 0, ret = 0;
 507         struct btrfs_key key;
 508         int nritems = btrfs_header_nritems(leaf);
 509
 510         for (i = 0; i < nritems; i++) {
 511                 btrfs_item_key_to_cpu(leaf, &key, i);
 512                 switch (key.type) {
 513                 case BTRFS_EXTENT_ITEM_KEY:
 514                         *num_bytes = key.offset;
 515                         fallthrough;
 516                 case BTRFS_METADATA_ITEM_KEY:
 517                         *bytenr = key.objectid;
 518                         ret = process_extent_item(fs_info, path, &key, i,
 519                                                   tree_block_level);
 520                         break;
 521                 case BTRFS_TREE_BLOCK_REF_KEY:
 522                         ret = add_tree_block(fs_info, key.offset, 0,
 523                                              key.objectid, *tree_block_level);
 524                         break;
 525                 case BTRFS_SHARED_BLOCK_REF_KEY:
 526                         ret = add_tree_block(fs_info, 0, key.offset,
 527                                              key.objectid, *tree_block_level);
 528                         break;
 529                 case BTRFS_EXTENT_DATA_REF_KEY:
 530                         dref = btrfs_item_ptr(leaf, i,
 531                                               struct btrfs_extent_data_ref);
 532                         ret = add_extent_data_ref(fs_info, leaf, dref, *bytenr,
 533                                                   *num_bytes);
 534                         break;
 535                 case BTRFS_SHARED_DATA_REF_KEY:
 536                         sref = btrfs_item_ptr(leaf, i,
 537                                               struct btrfs_shared_data_ref);
 538                         count = btrfs_shared_data_ref_count(leaf, sref);
 539                         ret = add_shared_data_ref(fs_info, key.offset, count,
 540                                                   *bytenr, *num_bytes);
 541                         break;
 542                 default:
 543                         break;
 544                 }
 545                 if (ret)
 546                         break;
 547         }
 548         return ret;
 549 }
 550
 551 /* Walk down to the leaf from the given level */
 552 static int walk_down_tree(struct btrfs_root *root, struct btrfs_path *path,
 553                           int level, u64 *bytenr, u64 *num_bytes,
 554                           int *tree_block_level)
 555 {
 556         struct extent_buffer *eb;
 557         int ret = 0;
 558
 559         while (level >= 0) {
 560                 if (level) {
 561                         eb = btrfs_read_node_slot(path->nodes[level],
 562                                                   path->slots[level]);
 563                         if (IS_ERR(eb))
 564                                 return PTR_ERR(eb);
 565                         btrfs_tree_read_lock(eb);
 566                         path->nodes[level-1] = eb;
 567                         path->slots[level-1] = 0;
 568                         path->locks[level-1] = BTRFS_READ_LOCK;
 569                 } else {
 570                         ret = process_leaf(root, path, bytenr, num_bytes,
 571                                            tree_block_level);
 572                         if (ret)
 573                                 break;
 574                 }
 575                 level--;
 576         }
 577         return ret;
 578 }
 579
 580 /* Walk up to the next node that needs to be processed */
 581 static int walk_up_tree(struct btrfs_path *path, int *level)
 582 {
 583         int l;
 584
 585         for (l = 0; l < BTRFS_MAX_LEVEL; l++) {
 586                 if (!path->nodes[l])
 587                         continue;
 588                 if (l) {
 589                         path->slots[l]++;
 590                         if (path->slots[l] <
 591                             btrfs_header_nritems(path->nodes[l])) {
 592                                 *level = l;
 593                                 return 0;
 594                         }
 595                 }
 596                 btrfs_tree_unlock_rw(path->nodes[l], path->locks[l]);
 597                 free_extent_buffer(path->nodes[l]);
 598                 path->nodes[l] = NULL;
 599                 path->slots[l] = 0;
 600                 path->locks[l] = 0;
 601         }
 602
 603         return 1;
 604 }
 605
 606 static void dump_ref_action(struct btrfs_fs_info *fs_info,
 607                             struct ref_action *ra)
 608 {
 609         btrfs_err(fs_info,
 610 "  Ref action %d, root %llu, ref_root %llu, parent %llu, owner %llu, offset %llu, num_refs %llu",
 611                   ra->action, ra->root, ra->ref.root_objectid, ra->ref.parent,
 612                   ra->ref.owner, ra->ref.offset, ra->ref.num_refs);
 613         __print_stack_trace(fs_info, ra);
 614 }
 615
 616 /*
 617  * Dumps all the information from the block entry to printk, it's going to be
 618  * awesome.
 619  */
 620 static void dump_block_entry(struct btrfs_fs_info *fs_info,
 621                              struct block_entry *be)
 622 {
 623         struct ref_entry *ref;
 624         struct root_entry *re;
 625         struct ref_action *ra;
 626         struct rb_node *n;
 627
 628         btrfs_err(fs_info,
 629 "dumping block entry [%llu %llu], num_refs %llu, metadata %d, from disk %d",
 630                   be->bytenr, be->len, be->num_refs, be->metadata,
 631                   be->from_disk);
 632
 633         for (n = rb_first(&be->refs); n; n = rb_next(n)) {
 634                 ref = rb_entry(n, struct ref_entry, node);
 635                 btrfs_err(fs_info,
 636 "  ref root %llu, parent %llu, owner %llu, offset %llu, num_refs %llu",
 637                           ref->root_objectid, ref->parent, ref->owner,
 638                           ref->offset, ref->num_refs);
 639         }
 640
 641         for (n = rb_first(&be->roots); n; n = rb_next(n)) {
 642                 re = rb_entry(n, struct root_entry, node);
 643                 btrfs_err(fs_info, "  root entry %llu, num_refs %llu",
 644                           re->root_objectid, re->num_refs);
 645         }
 646
 647         list_for_each_entry(ra, &be->actions, list)
 648                 dump_ref_action(fs_info, ra);
 649 }
 650
 651 /*
 652  * btrfs_ref_tree_mod: called when we modify a ref for a bytenr
 653  *
 654  * This will add an action item to the given bytenr and do sanity checks to make
 655  * sure we haven't messed something up.  If we are making a new allocation and
 656  * this block entry has history we will delete all previous actions as long as
 657  * our sanity checks pass as they are no longer needed.
 658  */
 659 int btrfs_ref_tree_mod(struct btrfs_fs_info *fs_info,
 660                        struct btrfs_ref *generic_ref)
 661 {
 662         struct ref_entry *ref = NULL, *exist;
 663         struct ref_action *ra = NULL;
 664         struct block_entry *be = NULL;
 665         struct root_entry *re = NULL;
 666         int action = generic_ref->action;
 667         int ret = 0;
 668         bool metadata;
 669         u64 bytenr = generic_ref->bytenr;
 670         u64 num_bytes = generic_ref->len;
 671         u64 parent = generic_ref->parent;
 672         u64 ref_root = 0;
 673         u64 owner = 0;
 674         u64 offset = 0;
 675
 676         if (!btrfs_test_opt(fs_info, REF_VERIFY))
 677                 return 0;
 678
 679         if (generic_ref->type == BTRFS_REF_METADATA) {
 680                 if (!parent)
 681                         ref_root = generic_ref->tree_ref.root;
 682                 owner = generic_ref->tree_ref.level;
 683         } else if (!parent) {
 684                 ref_root = generic_ref->data_ref.ref_root;
 685                 owner = generic_ref->data_ref.ino;
 686                 offset = generic_ref->data_ref.offset;
 687         }
 688         metadata = owner < BTRFS_FIRST_FREE_OBJECTID;
 689
 690         ref = kzalloc(sizeof(struct ref_entry), GFP_NOFS);
 691         ra = kmalloc(sizeof(struct ref_action), GFP_NOFS);
 692         if (!ra || !ref) {
 693                 kfree(ref);
 694                 kfree(ra);
 695                 ret = -ENOMEM;
 696                 goto out;
 697         }
 698
 699         ref->parent = parent;
 700         ref->owner = owner;
 701         ref->root_objectid = ref_root;
 702         ref->offset = offset;
 703         ref->num_refs = (action == BTRFS_DROP_DELAYED_REF) ? -1 : 1;
 704
 705         memcpy(&ra->ref, ref, sizeof(struct ref_entry));
 706         /*
 707          * Save the extra info from the delayed ref in the ref action to make it
 708          * easier to figure out what is happening.  The real ref's we add to the
 709          * ref tree need to reflect what we save on disk so it matches any
 710          * on-disk refs we pre-loaded.
 711          */
 712         ra->ref.owner = owner;
 713         ra->ref.offset = offset;
 714         ra->ref.root_objectid = ref_root;
 715         __save_stack_trace(ra);
 716
 717         INIT_LIST_HEAD(&ra->list);
 718         ra->action = action;
 719         ra->root = generic_ref->real_root;
 720
 721         /*
 722          * This is an allocation, preallocate the block_entry in case we haven't
 723          * used it before.
 724          */
 725         ret = -EINVAL;
 726         if (action == BTRFS_ADD_DELAYED_EXTENT) {
 727                 /*
 728                  * For subvol_create we'll just pass in whatever the parent root
 729                  * is and the new root objectid, so let's not treat the passed
 730                  * in root as if it really has a ref for this bytenr.
 731                  */
 732                 be = add_block_entry(fs_info, bytenr, num_bytes, ref_root);
 733                 if (IS_ERR(be)) {
 734                         kfree(ref);
 735                         kfree(ra);
 736                         ret = PTR_ERR(be);
 737                         goto out;
 738                 }
 739                 be->num_refs++;
 740                 if (metadata)
 741                         be->metadata = 1;
 742
 743                 if (be->num_refs != 1) {
 744                         btrfs_err(fs_info,
 745                         "re-allocated a block that still has references to it!");
 746                         dump_block_entry(fs_info, be);
 747                         dump_ref_action(fs_info, ra);
 748                         kfree(ref);
 749                         kfree(ra);
 750                         goto out_unlock;
 751                 }
 752
 753                 while (!list_empty(&be->actions)) {
 754                         struct ref_action *tmp;
 755
 756                         tmp = list_first_entry(&be->actions, struct ref_action,
 757                                                list);
 758                         list_del(&tmp->list);
 759                         kfree(tmp);
 760                 }
 761         } else {
 762                 struct root_entry *tmp;
 763
 764                 if (!parent) {
 765                         re = kmalloc(sizeof(struct root_entry), GFP_NOFS);
 766                         if (!re) {
 767                                 kfree(ref);
 768                                 kfree(ra);
 769                                 ret = -ENOMEM;
 770                                 goto out;
 771                         }
 772                         /*
 773                          * This is the root that is modifying us, so it's the
 774                          * one we want to lookup below when we modify the
 775                          * re->num_refs.
 776                          */
 777                         ref_root = generic_ref->real_root;
 778                         re->root_objectid = generic_ref->real_root;
 779                         re->num_refs = 0;
 780                 }
 781
 782                 spin_lock(&fs_info->ref_verify_lock);
 783                 be = lookup_block_entry(&fs_info->block_tree, bytenr);
 784                 if (!be) {
 785                         btrfs_err(fs_info,
 786 "trying to do action %d to bytenr %llu num_bytes %llu but there is no existing entry!",
 787                                   action, bytenr, num_bytes);
 788                         dump_ref_action(fs_info, ra);
 789                         kfree(ref);
 790                         kfree(ra);
 791                         goto out_unlock;
 792                 } else if (be->num_refs == 0) {
 793                         btrfs_err(fs_info,
 794                 "trying to do action %d for a bytenr that has 0 total references",
 795                                 action);
 796                         dump_block_entry(fs_info, be);
 797                         dump_ref_action(fs_info, ra);
 798                         kfree(ref);
 799                         kfree(ra);
 800                         goto out_unlock;
 801                 }
 802
 803                 if (!parent) {
 804                         tmp = insert_root_entry(&be->roots, re);
 805                         if (tmp) {
 806                                 kfree(re);
 807                                 re = tmp;
 808                         }
 809                 }
 810         }
 811
 812         exist = insert_ref_entry(&be->refs, ref);
 813         if (exist) {
 814                 if (action == BTRFS_DROP_DELAYED_REF) {
 815                         if (exist->num_refs == 0) {
 816                                 btrfs_err(fs_info,
 817 "dropping a ref for a existing root that doesn't have a ref on the block");
 818                                 dump_block_entry(fs_info, be);
 819                                 dump_ref_action(fs_info, ra);
 820                                 kfree(ref);
 821                                 kfree(ra);
 822                                 goto out_unlock;
 823                         }
 824                         exist->num_refs--;
 825                         if (exist->num_refs == 0) {
 826                                 rb_erase(&exist->node, &be->refs);
 827                                 kfree(exist);
 828                         }
 829                 } else if (!be->metadata) {
 830                         exist->num_refs++;
 831                 } else {
 832                         btrfs_err(fs_info,
 833 "attempting to add another ref for an existing ref on a tree block");
 834                         dump_block_entry(fs_info, be);
 835                         dump_ref_action(fs_info, ra);
 836                         kfree(ref);
 837                         kfree(ra);
 838                         goto out_unlock;
 839                 }
 840                 kfree(ref);
 841         } else {
 842                 if (action == BTRFS_DROP_DELAYED_REF) {
 843                         btrfs_err(fs_info,
 844 "dropping a ref for a root that doesn't have a ref on the block");
 845                         dump_block_entry(fs_info, be);
 846                         dump_ref_action(fs_info, ra);
 847                         kfree(ref);
 848                         kfree(ra);
 849                         goto out_unlock;
 850                 }
 851         }
 852
 853         if (!parent && !re) {
 854                 re = lookup_root_entry(&be->roots, ref_root);
 855                 if (!re) {
 856                         /*
 857                          * This shouldn't happen because we will add our re
 858                          * above when we lookup the be with !parent, but just in
 859                          * case catch this case so we don't panic because I
 860                          * didn't think of some other corner case.
 861                          */
 862                         btrfs_err(fs_info, "failed to find root %llu for %llu",
 863                                   generic_ref->real_root, be->bytenr);
 864                         dump_block_entry(fs_info, be);
 865                         dump_ref_action(fs_info, ra);
 866                         kfree(ra);
 867                         goto out_unlock;
 868                 }
 869         }
 870         if (action == BTRFS_DROP_DELAYED_REF) {
 871                 if (re)
 872                         re->num_refs--;
 873                 be->num_refs--;
 874         } else if (action == BTRFS_ADD_DELAYED_REF) {
 875                 be->num_refs++;
 876                 if (re)
 877                         re->num_refs++;
 878         }
 879         list_add_tail(&ra->list, &be->actions);
 880         ret = 0;
 881 out_unlock:
 882         spin_unlock(&fs_info->ref_verify_lock);
 883 out:
 884         if (ret)
 885                 btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
 886         return ret;
 887 }
 888
 889 /* Free up the ref cache */
 890 void btrfs_free_ref_cache(struct btrfs_fs_info *fs_info)
 891 {
 892         struct block_entry *be;
 893         struct rb_node *n;
 894
 895         if (!btrfs_test_opt(fs_info, REF_VERIFY))
 896                 return;
 897
 898         spin_lock(&fs_info->ref_verify_lock);
 899         while ((n = rb_first(&fs_info->block_tree))) {
 900                 be = rb_entry(n, struct block_entry, node);
 901                 rb_erase(&be->node, &fs_info->block_tree);
 902                 free_block_entry(be);
 903                 cond_resched_lock(&fs_info->ref_verify_lock);
 904         }
 905         spin_unlock(&fs_info->ref_verify_lock);
 906 }
 907
 908 void btrfs_free_ref_tree_range(struct btrfs_fs_info *fs_info, u64 start,
 909                                u64 len)
 910 {
 911         struct block_entry *be = NULL, *entry;
 912         struct rb_node *n;
 913
 914         if (!btrfs_test_opt(fs_info, REF_VERIFY))
 915                 return;
 916
 917         spin_lock(&fs_info->ref_verify_lock);
 918         n = fs_info->block_tree.rb_node;
 919         while (n) {
 920                 entry = rb_entry(n, struct block_entry, node);
 921                 if (entry->bytenr < start) {
 922                         n = n->rb_right;
 923                 } else if (entry->bytenr > start) {
 924                         n = n->rb_left;
 925                 } else {
 926                         be = entry;
 927                         break;
 928                 }
 929                 /* We want to get as close to start as possible */
 930                 if (be == NULL ||
 931                     (entry->bytenr < start && be->bytenr > start) ||
 932                     (entry->bytenr < start && entry->bytenr > be->bytenr))
 933                         be = entry;
 934         }
 935
 936         /*
 937          * Could have an empty block group, maybe have something to check for
 938          * this case to verify we were actually empty?
 939          */
 940         if (!be) {
 941                 spin_unlock(&fs_info->ref_verify_lock);
 942                 return;
 943         }
 944
 945         n = &be->node;
 946         while (n) {
 947                 be = rb_entry(n, struct block_entry, node);
 948                 n = rb_next(n);
 949                 if (be->bytenr < start && be->bytenr + be->len > start) {
 950                         btrfs_err(fs_info,
 951                                 "block entry overlaps a block group [%llu,%llu]!",
 952                                 start, len);
 953                         dump_block_entry(fs_info, be);
 954                         continue;
 955                 }
 956                 if (be->bytenr < start)
 957                         continue;
 958                 if (be->bytenr >= start + len)
 959                         break;
 960                 if (be->bytenr + be->len > start + len) {
 961                         btrfs_err(fs_info,
 962                                 "block entry overlaps a block group [%llu,%llu]!",
 963                                 start, len);
 964                         dump_block_entry(fs_info, be);
 965                 }
 966                 rb_erase(&be->node, &fs_info->block_tree);
 967                 free_block_entry(be);
 968         }
 969         spin_unlock(&fs_info->ref_verify_lock);
 970 }
 971
 972 /* Walk down all roots and build the ref tree, meant to be called at mount */
 973 int btrfs_build_ref_tree(struct btrfs_fs_info *fs_info)
 974 {
 975         struct btrfs_path *path;
 976         struct extent_buffer *eb;
 977         int tree_block_level = 0;
 978         u64 bytenr = 0, num_bytes = 0;
 979         int ret, level;
 980
 981         if (!btrfs_test_opt(fs_info, REF_VERIFY))
 982                 return 0;
 983
 984         path = btrfs_alloc_path();
 985         if (!path)
 986                 return -ENOMEM;
 987
 988         eb = btrfs_read_lock_root_node(fs_info->extent_root);
 989         level = btrfs_header_level(eb);
 990         path->nodes[level] = eb;
 991         path->slots[level] = 0;
 992         path->locks[level] = BTRFS_READ_LOCK;
 993
 994         while (1) {
 995                 /*
 996                  * We have to keep track of the bytenr/num_bytes we last hit
 997                  * because we could have run out of space for an inline ref, and
 998                  * would have had to added a ref key item which may appear on a
 999                  * different leaf from the original extent item.
1000                  */
1001                 ret = walk_down_tree(fs_info->extent_root, path, level,
1002                                      &bytenr, &num_bytes, &tree_block_level);
1003                 if (ret)
1004                         break;
1005                 ret = walk_up_tree(path, &level);
1006                 if (ret < 0)
1007                         break;
1008                 if (ret > 0) {
1009                         ret = 0;
1010                         break;
1011                 }
1012         }
1013         if (ret) {
1014                 btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
1015                 btrfs_free_ref_cache(fs_info);
1016         }
1017         btrfs_free_path(path);
1018         return ret;
1019 }