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 thats 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 occured 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         struct stack_trace stack_trace;
 209
 210         stack_trace.max_entries = MAX_TRACE;
 211         stack_trace.nr_entries = 0;
 212         stack_trace.entries = ra->trace;
 213         stack_trace.skip = 2;
 214         save_stack_trace(&stack_trace);
 215         ra->trace_len = stack_trace.nr_entries;
 216 }
 217
 218 static void __print_stack_trace(struct btrfs_fs_info *fs_info,
 219                                 struct ref_action *ra)
 220 {
 221         struct stack_trace trace;
 222
 223         if (ra->trace_len == 0) {
 224                 btrfs_err(fs_info, "  ref-verify: no stacktrace");
 225                 return;
 226         }
 227         trace.nr_entries = ra->trace_len;
 228         trace.entries = ra->trace;
 229         print_stack_trace(&trace, 2);
 230 }
 231 #else
 232 static void inline __save_stack_trace(struct ref_action *ra)
 233 {
 234 }
 235
 236 static void inline __print_stack_trace(struct btrfs_fs_info *fs_info,
 237                                        struct ref_action *ra)
 238 {
 239         btrfs_err(fs_info, "  ref-verify: no stacktrace support");
 240 }
 241 #endif
 242
 243 static void free_block_entry(struct block_entry *be)
 244 {
 245         struct root_entry *re;
 246         struct ref_entry *ref;
 247         struct ref_action *ra;
 248         struct rb_node *n;
 249
 250         while ((n = rb_first(&be->roots))) {
 251                 re = rb_entry(n, struct root_entry, node);
 252                 rb_erase(&re->node, &be->roots);
 253                 kfree(re);
 254         }
 255
 256         while((n = rb_first(&be->refs))) {
 257                 ref = rb_entry(n, struct ref_entry, node);
 258                 rb_erase(&ref->node, &be->refs);
 259                 kfree(ref);
 260         }
 261
 262         while (!list_empty(&be->actions)) {
 263                 ra = list_first_entry(&be->actions, struct ref_action,
 264                                       list);
 265                 list_del(&ra->list);
 266                 kfree(ra);
 267         }
 268         kfree(be);
 269 }
 270
 271 static struct block_entry *add_block_entry(struct btrfs_fs_info *fs_info,
 272                                            u64 bytenr, u64 len,
 273                                            u64 root_objectid)
 274 {
 275         struct block_entry *be = NULL, *exist;
 276         struct root_entry *re = NULL;
 277
 278         re = kzalloc(sizeof(struct root_entry), GFP_KERNEL);
 279         be = kzalloc(sizeof(struct block_entry), GFP_KERNEL);
 280         if (!be || !re) {
 281                 kfree(re);
 282                 kfree(be);
 283                 return ERR_PTR(-ENOMEM);
 284         }
 285         be->bytenr = bytenr;
 286         be->len = len;
 287
 288         re->root_objectid = root_objectid;
 289         re->num_refs = 0;
 290
 291         spin_lock(&fs_info->ref_verify_lock);
 292         exist = insert_block_entry(&fs_info->block_tree, be);
 293         if (exist) {
 294                 if (root_objectid) {
 295                         struct root_entry *exist_re;
 296
 297                         exist_re = insert_root_entry(&exist->roots, re);
 298                         if (exist_re)
 299                                 kfree(re);
 300                 } else {
 301                         kfree(re);
 302                 }
 303                 kfree(be);
 304                 return exist;
 305         }
 306
 307         be->num_refs = 0;
 308         be->metadata = 0;
 309         be->from_disk = 0;
 310         be->roots = RB_ROOT;
 311         be->refs = RB_ROOT;
 312         INIT_LIST_HEAD(&be->actions);
 313         if (root_objectid)
 314                 insert_root_entry(&be->roots, re);
 315         else
 316                 kfree(re);
 317         return be;
 318 }
 319
 320 static int add_tree_block(struct btrfs_fs_info *fs_info, u64 ref_root,
 321                           u64 parent, u64 bytenr, int level)
 322 {
 323         struct block_entry *be;
 324         struct root_entry *re;
 325         struct ref_entry *ref = NULL, *exist;
 326
 327         ref = kmalloc(sizeof(struct ref_entry), GFP_KERNEL);
 328         if (!ref)
 329                 return -ENOMEM;
 330
 331         if (parent)
 332                 ref->root_objectid = 0;
 333         else
 334                 ref->root_objectid = ref_root;
 335         ref->parent = parent;
 336         ref->owner = level;
 337         ref->offset = 0;
 338         ref->num_refs = 1;
 339
 340         be = add_block_entry(fs_info, bytenr, fs_info->nodesize, ref_root);
 341         if (IS_ERR(be)) {
 342                 kfree(ref);
 343                 return PTR_ERR(be);
 344         }
 345         be->num_refs++;
 346         be->from_disk = 1;
 347         be->metadata = 1;
 348
 349         if (!parent) {
 350                 ASSERT(ref_root);
 351                 re = lookup_root_entry(&be->roots, ref_root);
 352                 ASSERT(re);
 353                 re->num_refs++;
 354         }
 355         exist = insert_ref_entry(&be->refs, ref);
 356         if (exist) {
 357                 exist->num_refs++;
 358                 kfree(ref);
 359         }
 360         spin_unlock(&fs_info->ref_verify_lock);
 361
 362         return 0;
 363 }
 364
 365 static int add_shared_data_ref(struct btrfs_fs_info *fs_info,
 366                                u64 parent, u32 num_refs, u64 bytenr,
 367                                u64 num_bytes)
 368 {
 369         struct block_entry *be;
 370         struct ref_entry *ref;
 371
 372         ref = kzalloc(sizeof(struct ref_entry), GFP_KERNEL);
 373         if (!ref)
 374                 return -ENOMEM;
 375         be = add_block_entry(fs_info, bytenr, num_bytes, 0);
 376         if (IS_ERR(be)) {
 377                 kfree(ref);
 378                 return PTR_ERR(be);
 379         }
 380         be->num_refs += num_refs;
 381
 382         ref->parent = parent;
 383         ref->num_refs = num_refs;
 384         if (insert_ref_entry(&be->refs, ref)) {
 385                 spin_unlock(&fs_info->ref_verify_lock);
 386                 btrfs_err(fs_info, "existing shared ref when reading from disk?");
 387                 kfree(ref);
 388                 return -EINVAL;
 389         }
 390         spin_unlock(&fs_info->ref_verify_lock);
 391         return 0;
 392 }
 393
 394 static int add_extent_data_ref(struct btrfs_fs_info *fs_info,
 395                                struct extent_buffer *leaf,
 396                                struct btrfs_extent_data_ref *dref,
 397                                u64 bytenr, u64 num_bytes)
 398 {
 399         struct block_entry *be;
 400         struct ref_entry *ref;
 401         struct root_entry *re;
 402         u64 ref_root = btrfs_extent_data_ref_root(leaf, dref);
 403         u64 owner = btrfs_extent_data_ref_objectid(leaf, dref);
 404         u64 offset = btrfs_extent_data_ref_offset(leaf, dref);
 405         u32 num_refs = btrfs_extent_data_ref_count(leaf, dref);
 406
 407         ref = kzalloc(sizeof(struct ref_entry), GFP_KERNEL);
 408         if (!ref)
 409                 return -ENOMEM;
 410         be = add_block_entry(fs_info, bytenr, num_bytes, ref_root);
 411         if (IS_ERR(be)) {
 412                 kfree(ref);
 413                 return PTR_ERR(be);
 414         }
 415         be->num_refs += num_refs;
 416
 417         ref->parent = 0;
 418         ref->owner = owner;
 419         ref->root_objectid = ref_root;
 420         ref->offset = offset;
 421         ref->num_refs = num_refs;
 422         if (insert_ref_entry(&be->refs, ref)) {
 423                 spin_unlock(&fs_info->ref_verify_lock);
 424                 btrfs_err(fs_info, "existing ref when reading from disk?");
 425                 kfree(ref);
 426                 return -EINVAL;
 427         }
 428
 429         re = lookup_root_entry(&be->roots, ref_root);
 430         if (!re) {
 431                 spin_unlock(&fs_info->ref_verify_lock);
 432                 btrfs_err(fs_info, "missing root in new block entry?");
 433                 return -EINVAL;
 434         }
 435         re->num_refs += num_refs;
 436         spin_unlock(&fs_info->ref_verify_lock);
 437         return 0;
 438 }
 439
 440 static int process_extent_item(struct btrfs_fs_info *fs_info,
 441                                struct btrfs_path *path, struct btrfs_key *key,
 442                                int slot, int *tree_block_level)
 443 {
 444         struct btrfs_extent_item *ei;
 445         struct btrfs_extent_inline_ref *iref;
 446         struct btrfs_extent_data_ref *dref;
 447         struct btrfs_shared_data_ref *sref;
 448         struct extent_buffer *leaf = path->nodes[0];
 449         u32 item_size = btrfs_item_size_nr(leaf, slot);
 450         unsigned long end, ptr;
 451         u64 offset, flags, count;
 452         int type, ret;
 453
 454         ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 455         flags = btrfs_extent_flags(leaf, ei);
 456
 457         if ((key->type == BTRFS_EXTENT_ITEM_KEY) &&
 458             flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 459                 struct btrfs_tree_block_info *info;
 460
 461                 info = (struct btrfs_tree_block_info *)(ei + 1);
 462                 *tree_block_level = btrfs_tree_block_level(leaf, info);
 463                 iref = (struct btrfs_extent_inline_ref *)(info + 1);
 464         } else {
 465                 if (key->type == BTRFS_METADATA_ITEM_KEY)
 466                         *tree_block_level = key->offset;
 467                 iref = (struct btrfs_extent_inline_ref *)(ei + 1);
 468         }
 469
 470         ptr = (unsigned long)iref;
 471         end = (unsigned long)ei + item_size;
 472         while (ptr < end) {
 473                 iref = (struct btrfs_extent_inline_ref *)ptr;
 474                 type = btrfs_extent_inline_ref_type(leaf, iref);
 475                 offset = btrfs_extent_inline_ref_offset(leaf, iref);
 476                 switch (type) {
 477                 case BTRFS_TREE_BLOCK_REF_KEY:
 478                         ret = add_tree_block(fs_info, offset, 0, key->objectid,
 479                                              *tree_block_level);
 480                         break;
 481                 case BTRFS_SHARED_BLOCK_REF_KEY:
 482                         ret = add_tree_block(fs_info, 0, offset, key->objectid,
 483                                              *tree_block_level);
 484                         break;
 485                 case BTRFS_EXTENT_DATA_REF_KEY:
 486                         dref = (struct btrfs_extent_data_ref *)(&iref->offset);
 487                         ret = add_extent_data_ref(fs_info, leaf, dref,
 488                                                   key->objectid, key->offset);
 489                         break;
 490                 case BTRFS_SHARED_DATA_REF_KEY:
 491                         sref = (struct btrfs_shared_data_ref *)(iref + 1);
 492                         count = btrfs_shared_data_ref_count(leaf, sref);
 493                         ret = add_shared_data_ref(fs_info, offset, count,
 494                                                   key->objectid, key->offset);
 495                         break;
 496                 default:
 497                         btrfs_err(fs_info, "invalid key type in iref");
 498                         ret = -EINVAL;
 499                         break;
 500                 }
 501                 if (ret)
 502                         break;
 503                 ptr += btrfs_extent_inline_ref_size(type);
 504         }
 505         return ret;
 506 }
 507
 508 static int process_leaf(struct btrfs_root *root,
 509                         struct btrfs_path *path, u64 *bytenr, u64 *num_bytes)
 510 {
 511         struct btrfs_fs_info *fs_info = root->fs_info;
 512         struct extent_buffer *leaf = path->nodes[0];
 513         struct btrfs_extent_data_ref *dref;
 514         struct btrfs_shared_data_ref *sref;
 515         u32 count;
 516         int i = 0, tree_block_level = 0, ret = 0;
 517         struct btrfs_key key;
 518         int nritems = btrfs_header_nritems(leaf);
 519
 520         for (i = 0; i < nritems; i++) {
 521                 btrfs_item_key_to_cpu(leaf, &key, i);
 522                 switch (key.type) {
 523                 case BTRFS_EXTENT_ITEM_KEY:
 524                         *num_bytes = key.offset;
 525                 case BTRFS_METADATA_ITEM_KEY:
 526                         *bytenr = key.objectid;
 527                         ret = process_extent_item(fs_info, path, &key, i,
 528                                                   &tree_block_level);
 529                         break;
 530                 case BTRFS_TREE_BLOCK_REF_KEY:
 531                         ret = add_tree_block(fs_info, key.offset, 0,
 532                                              key.objectid, tree_block_level);
 533                         break;
 534                 case BTRFS_SHARED_BLOCK_REF_KEY:
 535                         ret = add_tree_block(fs_info, 0, key.offset,
 536                                              key.objectid, tree_block_level);
 537                         break;
 538                 case BTRFS_EXTENT_DATA_REF_KEY:
 539                         dref = btrfs_item_ptr(leaf, i,
 540                                               struct btrfs_extent_data_ref);
 541                         ret = add_extent_data_ref(fs_info, leaf, dref, *bytenr,
 542                                                   *num_bytes);
 543                         break;
 544                 case BTRFS_SHARED_DATA_REF_KEY:
 545                         sref = btrfs_item_ptr(leaf, i,
 546                                               struct btrfs_shared_data_ref);
 547                         count = btrfs_shared_data_ref_count(leaf, sref);
 548                         ret = add_shared_data_ref(fs_info, key.offset, count,
 549                                                   *bytenr, *num_bytes);
 550                         break;
 551                 default:
 552                         break;
 553                 }
 554                 if (ret)
 555                         break;
 556         }
 557         return ret;
 558 }
 559
 560 /* Walk down to the leaf from the given level */
 561 static int walk_down_tree(struct btrfs_root *root, struct btrfs_path *path,
 562                           int level, u64 *bytenr, u64 *num_bytes)
 563 {
 564         struct btrfs_fs_info *fs_info = root->fs_info;
 565         struct extent_buffer *eb;
 566         u64 block_bytenr, gen;
 567         int ret = 0;
 568
 569         while (level >= 0) {
 570                 if (level) {
 571                         struct btrfs_key first_key;
 572
 573                         block_bytenr = btrfs_node_blockptr(path->nodes[level],
 574                                                            path->slots[level]);
 575                         gen = btrfs_node_ptr_generation(path->nodes[level],
 576                                                         path->slots[level]);
 577                         btrfs_node_key_to_cpu(path->nodes[level], &first_key,
 578                                               path->slots[level]);
 579                         eb = read_tree_block(fs_info, block_bytenr, gen,
 580                                              level - 1, &first_key);
 581                         if (IS_ERR(eb))
 582                                 return PTR_ERR(eb);
 583                         if (!extent_buffer_uptodate(eb)) {
 584                                 free_extent_buffer(eb);
 585                                 return -EIO;
 586                         }
 587                         btrfs_tree_read_lock(eb);
 588                         btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
 589                         path->nodes[level-1] = eb;
 590                         path->slots[level-1] = 0;
 591                         path->locks[level-1] = BTRFS_READ_LOCK_BLOCKING;
 592                 } else {
 593                         ret = process_leaf(root, path, bytenr, num_bytes);
 594                         if (ret)
 595                                 break;
 596                 }
 597                 level--;
 598         }
 599         return ret;
 600 }
 601
 602 /* Walk up to the next node that needs to be processed */
 603 static int walk_up_tree(struct btrfs_path *path, int *level)
 604 {
 605         int l;
 606
 607         for (l = 0; l < BTRFS_MAX_LEVEL; l++) {
 608                 if (!path->nodes[l])
 609                         continue;
 610                 if (l) {
 611                         path->slots[l]++;
 612                         if (path->slots[l] <
 613                             btrfs_header_nritems(path->nodes[l])) {
 614                                 *level = l;
 615                                 return 0;
 616                         }
 617                 }
 618                 btrfs_tree_unlock_rw(path->nodes[l], path->locks[l]);
 619                 free_extent_buffer(path->nodes[l]);
 620                 path->nodes[l] = NULL;
 621                 path->slots[l] = 0;
 622                 path->locks[l] = 0;
 623         }
 624
 625         return 1;
 626 }
 627
 628 static void dump_ref_action(struct btrfs_fs_info *fs_info,
 629                             struct ref_action *ra)
 630 {
 631         btrfs_err(fs_info,
 632 "  Ref action %d, root %llu, ref_root %llu, parent %llu, owner %llu, offset %llu, num_refs %llu",
 633                   ra->action, ra->root, ra->ref.root_objectid, ra->ref.parent,
 634                   ra->ref.owner, ra->ref.offset, ra->ref.num_refs);
 635         __print_stack_trace(fs_info, ra);
 636 }
 637
 638 /*
 639  * Dumps all the information from the block entry to printk, it's going to be
 640  * awesome.
 641  */
 642 static void dump_block_entry(struct btrfs_fs_info *fs_info,
 643                              struct block_entry *be)
 644 {
 645         struct ref_entry *ref;
 646         struct root_entry *re;
 647         struct ref_action *ra;
 648         struct rb_node *n;
 649
 650         btrfs_err(fs_info,
 651 "dumping block entry [%llu %llu], num_refs %llu, metadata %d, from disk %d",
 652                   be->bytenr, be->len, be->num_refs, be->metadata,
 653                   be->from_disk);
 654
 655         for (n = rb_first(&be->refs); n; n = rb_next(n)) {
 656                 ref = rb_entry(n, struct ref_entry, node);
 657                 btrfs_err(fs_info,
 658 "  ref root %llu, parent %llu, owner %llu, offset %llu, num_refs %llu",
 659                           ref->root_objectid, ref->parent, ref->owner,
 660                           ref->offset, ref->num_refs);
 661         }
 662
 663         for (n = rb_first(&be->roots); n; n = rb_next(n)) {
 664                 re = rb_entry(n, struct root_entry, node);
 665                 btrfs_err(fs_info, "  root entry %llu, num_refs %llu",
 666                           re->root_objectid, re->num_refs);
 667         }
 668
 669         list_for_each_entry(ra, &be->actions, list)
 670                 dump_ref_action(fs_info, ra);
 671 }
 672
 673 /*
 674  * btrfs_ref_tree_mod: called when we modify a ref for a bytenr
 675  * @root: the root we are making this modification from.
 676  * @bytenr: the bytenr we are modifying.
 677  * @num_bytes: number of bytes.
 678  * @parent: the parent bytenr.
 679  * @ref_root: the original root owner of the bytenr.
 680  * @owner: level in the case of metadata, inode in the case of data.
 681  * @offset: 0 for metadata, file offset for data.
 682  * @action: the action that we are doing, this is the same as the delayed ref
 683  *      action.
 684  *
 685  * This will add an action item to the given bytenr and do sanity checks to make
 686  * sure we haven't messed something up.  If we are making a new allocation and
 687  * this block entry has history we will delete all previous actions as long as
 688  * our sanity checks pass as they are no longer needed.
 689  */
 690 int btrfs_ref_tree_mod(struct btrfs_root *root, u64 bytenr, u64 num_bytes,
 691                        u64 parent, u64 ref_root, u64 owner, u64 offset,
 692                        int action)
 693 {
 694         struct btrfs_fs_info *fs_info = root->fs_info;
 695         struct ref_entry *ref = NULL, *exist;
 696         struct ref_action *ra = NULL;
 697         struct block_entry *be = NULL;
 698         struct root_entry *re = NULL;
 699         int ret = 0;
 700         bool metadata = owner < BTRFS_FIRST_FREE_OBJECTID;
 701
 702         if (!btrfs_test_opt(root->fs_info, REF_VERIFY))
 703                 return 0;
 704
 705         ref = kzalloc(sizeof(struct ref_entry), GFP_NOFS);
 706         ra = kmalloc(sizeof(struct ref_action), GFP_NOFS);
 707         if (!ra || !ref) {
 708                 kfree(ref);
 709                 kfree(ra);
 710                 ret = -ENOMEM;
 711                 goto out;
 712         }
 713
 714         if (parent) {
 715                 ref->parent = parent;
 716         } else {
 717                 ref->root_objectid = ref_root;
 718                 ref->owner = owner;
 719                 ref->offset = offset;
 720         }
 721         ref->num_refs = (action == BTRFS_DROP_DELAYED_REF) ? -1 : 1;
 722
 723         memcpy(&ra->ref, ref, sizeof(struct ref_entry));
 724         /*
 725          * Save the extra info from the delayed ref in the ref action to make it
 726          * easier to figure out what is happening.  The real ref's we add to the
 727          * ref tree need to reflect what we save on disk so it matches any
 728          * on-disk refs we pre-loaded.
 729          */
 730         ra->ref.owner = owner;
 731         ra->ref.offset = offset;
 732         ra->ref.root_objectid = ref_root;
 733         __save_stack_trace(ra);
 734
 735         INIT_LIST_HEAD(&ra->list);
 736         ra->action = action;
 737         ra->root = root->objectid;
 738
 739         /*
 740          * This is an allocation, preallocate the block_entry in case we haven't
 741          * used it before.
 742          */
 743         ret = -EINVAL;
 744         if (action == BTRFS_ADD_DELAYED_EXTENT) {
 745                 /*
 746                  * For subvol_create we'll just pass in whatever the parent root
 747                  * is and the new root objectid, so let's not treat the passed
 748                  * in root as if it really has a ref for this bytenr.
 749                  */
 750                 be = add_block_entry(root->fs_info, bytenr, num_bytes, ref_root);
 751                 if (IS_ERR(be)) {
 752                         kfree(ref);
 753                         kfree(ra);
 754                         ret = PTR_ERR(be);
 755                         goto out;
 756                 }
 757                 be->num_refs++;
 758                 if (metadata)
 759                         be->metadata = 1;
 760
 761                 if (be->num_refs != 1) {
 762                         btrfs_err(fs_info,
 763                         "re-allocated a block that still has references to it!");
 764                         dump_block_entry(fs_info, be);
 765                         dump_ref_action(fs_info, ra);
 766                         kfree(ref);
 767                         kfree(ra);
 768                         goto out_unlock;
 769                 }
 770
 771                 while (!list_empty(&be->actions)) {
 772                         struct ref_action *tmp;
 773
 774                         tmp = list_first_entry(&be->actions, struct ref_action,
 775                                                list);
 776                         list_del(&tmp->list);
 777                         kfree(tmp);
 778                 }
 779         } else {
 780                 struct root_entry *tmp;
 781
 782                 if (!parent) {
 783                         re = kmalloc(sizeof(struct root_entry), GFP_NOFS);
 784                         if (!re) {
 785                                 kfree(ref);
 786                                 kfree(ra);
 787                                 ret = -ENOMEM;
 788                                 goto out;
 789                         }
 790                         /*
 791                          * This is the root that is modifying us, so it's the
 792                          * one we want to lookup below when we modify the
 793                          * re->num_refs.
 794                          */
 795                         ref_root = root->objectid;
 796                         re->root_objectid = root->objectid;
 797                         re->num_refs = 0;
 798                 }
 799
 800                 spin_lock(&root->fs_info->ref_verify_lock);
 801                 be = lookup_block_entry(&root->fs_info->block_tree, bytenr);
 802                 if (!be) {
 803                         btrfs_err(fs_info,
 804 "trying to do action %d to bytenr %llu num_bytes %llu but there is no existing entry!",
 805                                   action, (unsigned long long)bytenr,
 806                                   (unsigned long long)num_bytes);
 807                         dump_ref_action(fs_info, ra);
 808                         kfree(ref);
 809                         kfree(ra);
 810                         goto out_unlock;
 811                 }
 812
 813                 if (!parent) {
 814                         tmp = insert_root_entry(&be->roots, re);
 815                         if (tmp) {
 816                                 kfree(re);
 817                                 re = tmp;
 818                         }
 819                 }
 820         }
 821
 822         exist = insert_ref_entry(&be->refs, ref);
 823         if (exist) {
 824                 if (action == BTRFS_DROP_DELAYED_REF) {
 825                         if (exist->num_refs == 0) {
 826                                 btrfs_err(fs_info,
 827 "dropping a ref for a existing root that doesn't have a ref on the block");
 828                                 dump_block_entry(fs_info, be);
 829                                 dump_ref_action(fs_info, ra);
 830                                 kfree(ref);
 831                                 kfree(ra);
 832                                 goto out_unlock;
 833                         }
 834                         exist->num_refs--;
 835                         if (exist->num_refs == 0) {
 836                                 rb_erase(&exist->node, &be->refs);
 837                                 kfree(exist);
 838                         }
 839                 } else if (!be->metadata) {
 840                         exist->num_refs++;
 841                 } else {
 842                         btrfs_err(fs_info,
 843 "attempting to add another ref for an existing ref on a tree block");
 844                         dump_block_entry(fs_info, be);
 845                         dump_ref_action(fs_info, ra);
 846                         kfree(ref);
 847                         kfree(ra);
 848                         goto out_unlock;
 849                 }
 850                 kfree(ref);
 851         } else {
 852                 if (action == BTRFS_DROP_DELAYED_REF) {
 853                         btrfs_err(fs_info,
 854 "dropping a ref for a root that doesn't have a ref on the block");
 855                         dump_block_entry(fs_info, be);
 856                         dump_ref_action(fs_info, ra);
 857                         kfree(ref);
 858                         kfree(ra);
 859                         goto out_unlock;
 860                 }
 861         }
 862
 863         if (!parent && !re) {
 864                 re = lookup_root_entry(&be->roots, ref_root);
 865                 if (!re) {
 866                         /*
 867                          * This shouldn't happen because we will add our re
 868                          * above when we lookup the be with !parent, but just in
 869                          * case catch this case so we don't panic because I
 870                          * didn't thik of some other corner case.
 871                          */
 872                         btrfs_err(fs_info, "failed to find root %llu for %llu",
 873                                   root->objectid, be->bytenr);
 874                         dump_block_entry(fs_info, be);
 875                         dump_ref_action(fs_info, ra);
 876                         kfree(ra);
 877                         goto out_unlock;
 878                 }
 879         }
 880         if (action == BTRFS_DROP_DELAYED_REF) {
 881                 if (re)
 882                         re->num_refs--;
 883                 be->num_refs--;
 884         } else if (action == BTRFS_ADD_DELAYED_REF) {
 885                 be->num_refs++;
 886                 if (re)
 887                         re->num_refs++;
 888         }
 889         list_add_tail(&ra->list, &be->actions);
 890         ret = 0;
 891 out_unlock:
 892         spin_unlock(&root->fs_info->ref_verify_lock);
 893 out:
 894         if (ret)
 895                 btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
 896         return ret;
 897 }
 898
 899 /* Free up the ref cache */
 900 void btrfs_free_ref_cache(struct btrfs_fs_info *fs_info)
 901 {
 902         struct block_entry *be;
 903         struct rb_node *n;
 904
 905         if (!btrfs_test_opt(fs_info, REF_VERIFY))
 906                 return;
 907
 908         spin_lock(&fs_info->ref_verify_lock);
 909         while ((n = rb_first(&fs_info->block_tree))) {
 910                 be = rb_entry(n, struct block_entry, node);
 911                 rb_erase(&be->node, &fs_info->block_tree);
 912                 free_block_entry(be);
 913                 cond_resched_lock(&fs_info->ref_verify_lock);
 914         }
 915         spin_unlock(&fs_info->ref_verify_lock);
 916 }
 917
 918 void btrfs_free_ref_tree_range(struct btrfs_fs_info *fs_info, u64 start,
 919                                u64 len)
 920 {
 921         struct block_entry *be = NULL, *entry;
 922         struct rb_node *n;
 923
 924         if (!btrfs_test_opt(fs_info, REF_VERIFY))
 925                 return;
 926
 927         spin_lock(&fs_info->ref_verify_lock);
 928         n = fs_info->block_tree.rb_node;
 929         while (n) {
 930                 entry = rb_entry(n, struct block_entry, node);
 931                 if (entry->bytenr < start) {
 932                         n = n->rb_right;
 933                 } else if (entry->bytenr > start) {
 934                         n = n->rb_left;
 935                 } else {
 936                         be = entry;
 937                         break;
 938                 }
 939                 /* We want to get as close to start as possible */
 940                 if (be == NULL ||
 941                     (entry->bytenr < start && be->bytenr > start) ||
 942                     (entry->bytenr < start && entry->bytenr > be->bytenr))
 943                         be = entry;
 944         }
 945
 946         /*
 947          * Could have an empty block group, maybe have something to check for
 948          * this case to verify we were actually empty?
 949          */
 950         if (!be) {
 951                 spin_unlock(&fs_info->ref_verify_lock);
 952                 return;
 953         }
 954
 955         n = &be->node;
 956         while (n) {
 957                 be = rb_entry(n, struct block_entry, node);
 958                 n = rb_next(n);
 959                 if (be->bytenr < start && be->bytenr + be->len > start) {
 960                         btrfs_err(fs_info,
 961                                 "block entry overlaps a block group [%llu,%llu]!",
 962                                 start, len);
 963                         dump_block_entry(fs_info, be);
 964                         continue;
 965                 }
 966                 if (be->bytenr < start)
 967                         continue;
 968                 if (be->bytenr >= start + len)
 969                         break;
 970                 if (be->bytenr + be->len > start + len) {
 971                         btrfs_err(fs_info,
 972                                 "block entry overlaps a block group [%llu,%llu]!",
 973                                 start, len);
 974                         dump_block_entry(fs_info, be);
 975                 }
 976                 rb_erase(&be->node, &fs_info->block_tree);
 977                 free_block_entry(be);
 978         }
 979         spin_unlock(&fs_info->ref_verify_lock);
 980 }
 981
 982 /* Walk down all roots and build the ref tree, meant to be called at mount */
 983 int btrfs_build_ref_tree(struct btrfs_fs_info *fs_info)
 984 {
 985         struct btrfs_path *path;
 986         struct extent_buffer *eb;
 987         u64 bytenr = 0, num_bytes = 0;
 988         int ret, level;
 989
 990         if (!btrfs_test_opt(fs_info, REF_VERIFY))
 991                 return 0;
 992
 993         path = btrfs_alloc_path();
 994         if (!path)
 995                 return -ENOMEM;
 996
 997         eb = btrfs_read_lock_root_node(fs_info->extent_root);
 998         btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
 999         level = btrfs_header_level(eb);
1000         path->nodes[level] = eb;
1001         path->slots[level] = 0;
1002         path->locks[level] = BTRFS_READ_LOCK_BLOCKING;
1003
1004         while (1) {
1005                 /*
1006                  * We have to keep track of the bytenr/num_bytes we last hit
1007                  * because we could have run out of space for an inline ref, and
1008                  * would have had to added a ref key item which may appear on a
1009                  * different leaf from the original extent item.
1010                  */
1011                 ret = walk_down_tree(fs_info->extent_root, path, level,
1012                                      &bytenr, &num_bytes);
1013                 if (ret)
1014                         break;
1015                 ret = walk_up_tree(path, &level);
1016                 if (ret < 0)
1017                         break;
1018                 if (ret > 0) {
1019                         ret = 0;
1020                         break;
1021                 }
1022         }
1023         if (ret) {
1024                 btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
1025                 btrfs_free_ref_cache(fs_info);
1026         }
1027         btrfs_free_path(path);
1028         return ret;
1029 }