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 void inline __save_stack_trace(struct ref_action *ra)
 222 {
 223 }
 224
 225 static void inline __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 {
 500         struct btrfs_fs_info *fs_info = root->fs_info;
 501         struct extent_buffer *leaf = path->nodes[0];
 502         struct btrfs_extent_data_ref *dref;
 503         struct btrfs_shared_data_ref *sref;
 504         u32 count;
 505         int i = 0, tree_block_level = 0, ret = 0;
 506         struct btrfs_key key;
 507         int nritems = btrfs_header_nritems(leaf);
 508
 509         for (i = 0; i < nritems; i++) {
 510                 btrfs_item_key_to_cpu(leaf, &key, i);
 511                 switch (key.type) {
 512                 case BTRFS_EXTENT_ITEM_KEY:
 513                         *num_bytes = key.offset;
 514                         fallthrough;
 515                 case BTRFS_METADATA_ITEM_KEY:
 516                         *bytenr = key.objectid;
 517                         ret = process_extent_item(fs_info, path, &key, i,
 518                                                   &tree_block_level);
 519                         break;
 520                 case BTRFS_TREE_BLOCK_REF_KEY:
 521                         ret = add_tree_block(fs_info, key.offset, 0,
 522                                              key.objectid, tree_block_level);
 523                         break;
 524                 case BTRFS_SHARED_BLOCK_REF_KEY:
 525                         ret = add_tree_block(fs_info, 0, key.offset,
 526                                              key.objectid, tree_block_level);
 527                         break;
 528                 case BTRFS_EXTENT_DATA_REF_KEY:
 529                         dref = btrfs_item_ptr(leaf, i,
 530                                               struct btrfs_extent_data_ref);
 531                         ret = add_extent_data_ref(fs_info, leaf, dref, *bytenr,
 532                                                   *num_bytes);
 533                         break;
 534                 case BTRFS_SHARED_DATA_REF_KEY:
 535                         sref = btrfs_item_ptr(leaf, i,
 536                                               struct btrfs_shared_data_ref);
 537                         count = btrfs_shared_data_ref_count(leaf, sref);
 538                         ret = add_shared_data_ref(fs_info, key.offset, count,
 539                                                   *bytenr, *num_bytes);
 540                         break;
 541                 default:
 542                         break;
 543                 }
 544                 if (ret)
 545                         break;
 546         }
 547         return ret;
 548 }
 549
 550 /* Walk down to the leaf from the given level */
 551 static int walk_down_tree(struct btrfs_root *root, struct btrfs_path *path,
 552                           int level, u64 *bytenr, u64 *num_bytes)
 553 {
 554         struct btrfs_fs_info *fs_info = root->fs_info;
 555         struct extent_buffer *eb;
 556         u64 block_bytenr, gen;
 557         int ret = 0;
 558
 559         while (level >= 0) {
 560                 if (level) {
 561                         struct btrfs_key first_key;
 562
 563                         block_bytenr = btrfs_node_blockptr(path->nodes[level],
 564                                                            path->slots[level]);
 565                         gen = btrfs_node_ptr_generation(path->nodes[level],
 566                                                         path->slots[level]);
 567                         btrfs_node_key_to_cpu(path->nodes[level], &first_key,
 568                                               path->slots[level]);
 569                         eb = read_tree_block(fs_info, block_bytenr, gen,
 570                                              level - 1, &first_key);
 571                         if (IS_ERR(eb))
 572                                 return PTR_ERR(eb);
 573                         if (!extent_buffer_uptodate(eb)) {
 574                                 free_extent_buffer(eb);
 575                                 return -EIO;
 576                         }
 577                         btrfs_tree_read_lock(eb);
 578                         btrfs_set_lock_blocking_read(eb);
 579                         path->nodes[level-1] = eb;
 580                         path->slots[level-1] = 0;
 581                         path->locks[level-1] = BTRFS_READ_LOCK_BLOCKING;
 582                 } else {
 583                         ret = process_leaf(root, path, bytenr, num_bytes);
 584                         if (ret)
 585                                 break;
 586                 }
 587                 level--;
 588         }
 589         return ret;
 590 }
 591
 592 /* Walk up to the next node that needs to be processed */
 593 static int walk_up_tree(struct btrfs_path *path, int *level)
 594 {
 595         int l;
 596
 597         for (l = 0; l < BTRFS_MAX_LEVEL; l++) {
 598                 if (!path->nodes[l])
 599                         continue;
 600                 if (l) {
 601                         path->slots[l]++;
 602                         if (path->slots[l] <
 603                             btrfs_header_nritems(path->nodes[l])) {
 604                                 *level = l;
 605                                 return 0;
 606                         }
 607                 }
 608                 btrfs_tree_unlock_rw(path->nodes[l], path->locks[l]);
 609                 free_extent_buffer(path->nodes[l]);
 610                 path->nodes[l] = NULL;
 611                 path->slots[l] = 0;
 612                 path->locks[l] = 0;
 613         }
 614
 615         return 1;
 616 }
 617
 618 static void dump_ref_action(struct btrfs_fs_info *fs_info,
 619                             struct ref_action *ra)
 620 {
 621         btrfs_err(fs_info,
 622 "  Ref action %d, root %llu, ref_root %llu, parent %llu, owner %llu, offset %llu, num_refs %llu",
 623                   ra->action, ra->root, ra->ref.root_objectid, ra->ref.parent,
 624                   ra->ref.owner, ra->ref.offset, ra->ref.num_refs);
 625         __print_stack_trace(fs_info, ra);
 626 }
 627
 628 /*
 629  * Dumps all the information from the block entry to printk, it's going to be
 630  * awesome.
 631  */
 632 static void dump_block_entry(struct btrfs_fs_info *fs_info,
 633                              struct block_entry *be)
 634 {
 635         struct ref_entry *ref;
 636         struct root_entry *re;
 637         struct ref_action *ra;
 638         struct rb_node *n;
 639
 640         btrfs_err(fs_info,
 641 "dumping block entry [%llu %llu], num_refs %llu, metadata %d, from disk %d",
 642                   be->bytenr, be->len, be->num_refs, be->metadata,
 643                   be->from_disk);
 644
 645         for (n = rb_first(&be->refs); n; n = rb_next(n)) {
 646                 ref = rb_entry(n, struct ref_entry, node);
 647                 btrfs_err(fs_info,
 648 "  ref root %llu, parent %llu, owner %llu, offset %llu, num_refs %llu",
 649                           ref->root_objectid, ref->parent, ref->owner,
 650                           ref->offset, ref->num_refs);
 651         }
 652
 653         for (n = rb_first(&be->roots); n; n = rb_next(n)) {
 654                 re = rb_entry(n, struct root_entry, node);
 655                 btrfs_err(fs_info, "  root entry %llu, num_refs %llu",
 656                           re->root_objectid, re->num_refs);
 657         }
 658
 659         list_for_each_entry(ra, &be->actions, list)
 660                 dump_ref_action(fs_info, ra);
 661 }
 662
 663 /*
 664  * btrfs_ref_tree_mod: called when we modify a ref for a bytenr
 665  *
 666  * This will add an action item to the given bytenr and do sanity checks to make
 667  * sure we haven't messed something up.  If we are making a new allocation and
 668  * this block entry has history we will delete all previous actions as long as
 669  * our sanity checks pass as they are no longer needed.
 670  */
 671 int btrfs_ref_tree_mod(struct btrfs_fs_info *fs_info,
 672                        struct btrfs_ref *generic_ref)
 673 {
 674         struct ref_entry *ref = NULL, *exist;
 675         struct ref_action *ra = NULL;
 676         struct block_entry *be = NULL;
 677         struct root_entry *re = NULL;
 678         int action = generic_ref->action;
 679         int ret = 0;
 680         bool metadata;
 681         u64 bytenr = generic_ref->bytenr;
 682         u64 num_bytes = generic_ref->len;
 683         u64 parent = generic_ref->parent;
 684         u64 ref_root;
 685         u64 owner;
 686         u64 offset;
 687
 688         if (!btrfs_test_opt(fs_info, REF_VERIFY))
 689                 return 0;
 690
 691         if (generic_ref->type == BTRFS_REF_METADATA) {
 692                 ref_root = generic_ref->tree_ref.root;
 693                 owner = generic_ref->tree_ref.level;
 694                 offset = 0;
 695         } else {
 696                 ref_root = generic_ref->data_ref.ref_root;
 697                 owner = generic_ref->data_ref.ino;
 698                 offset = generic_ref->data_ref.offset;
 699         }
 700         metadata = owner < BTRFS_FIRST_FREE_OBJECTID;
 701
 702         ref = kzalloc(sizeof(struct ref_entry), GFP_NOFS);
 703         ra = kmalloc(sizeof(struct ref_action), GFP_NOFS);
 704         if (!ra || !ref) {
 705                 kfree(ref);
 706                 kfree(ra);
 707                 ret = -ENOMEM;
 708                 goto out;
 709         }
 710
 711         if (parent) {
 712                 ref->parent = parent;
 713         } else {
 714                 ref->root_objectid = ref_root;
 715                 ref->owner = owner;
 716                 ref->offset = offset;
 717         }
 718         ref->num_refs = (action == BTRFS_DROP_DELAYED_REF) ? -1 : 1;
 719
 720         memcpy(&ra->ref, ref, sizeof(struct ref_entry));
 721         /*
 722          * Save the extra info from the delayed ref in the ref action to make it
 723          * easier to figure out what is happening.  The real ref's we add to the
 724          * ref tree need to reflect what we save on disk so it matches any
 725          * on-disk refs we pre-loaded.
 726          */
 727         ra->ref.owner = owner;
 728         ra->ref.offset = offset;
 729         ra->ref.root_objectid = ref_root;
 730         __save_stack_trace(ra);
 731
 732         INIT_LIST_HEAD(&ra->list);
 733         ra->action = action;
 734         ra->root = generic_ref->real_root;
 735
 736         /*
 737          * This is an allocation, preallocate the block_entry in case we haven't
 738          * used it before.
 739          */
 740         ret = -EINVAL;
 741         if (action == BTRFS_ADD_DELAYED_EXTENT) {
 742                 /*
 743                  * For subvol_create we'll just pass in whatever the parent root
 744                  * is and the new root objectid, so let's not treat the passed
 745                  * in root as if it really has a ref for this bytenr.
 746                  */
 747                 be = add_block_entry(fs_info, bytenr, num_bytes, ref_root);
 748                 if (IS_ERR(be)) {
 749                         kfree(ref);
 750                         kfree(ra);
 751                         ret = PTR_ERR(be);
 752                         goto out;
 753                 }
 754                 be->num_refs++;
 755                 if (metadata)
 756                         be->metadata = 1;
 757
 758                 if (be->num_refs != 1) {
 759                         btrfs_err(fs_info,
 760                         "re-allocated a block that still has references to it!");
 761                         dump_block_entry(fs_info, be);
 762                         dump_ref_action(fs_info, ra);
 763                         kfree(ref);
 764                         kfree(ra);
 765                         goto out_unlock;
 766                 }
 767
 768                 while (!list_empty(&be->actions)) {
 769                         struct ref_action *tmp;
 770
 771                         tmp = list_first_entry(&be->actions, struct ref_action,
 772                                                list);
 773                         list_del(&tmp->list);
 774                         kfree(tmp);
 775                 }
 776         } else {
 777                 struct root_entry *tmp;
 778
 779                 if (!parent) {
 780                         re = kmalloc(sizeof(struct root_entry), GFP_NOFS);
 781                         if (!re) {
 782                                 kfree(ref);
 783                                 kfree(ra);
 784                                 ret = -ENOMEM;
 785                                 goto out;
 786                         }
 787                         /*
 788                          * This is the root that is modifying us, so it's the
 789                          * one we want to lookup below when we modify the
 790                          * re->num_refs.
 791                          */
 792                         ref_root = generic_ref->real_root;
 793                         re->root_objectid = generic_ref->real_root;
 794                         re->num_refs = 0;
 795                 }
 796
 797                 spin_lock(&fs_info->ref_verify_lock);
 798                 be = lookup_block_entry(&fs_info->block_tree, bytenr);
 799                 if (!be) {
 800                         btrfs_err(fs_info,
 801 "trying to do action %d to bytenr %llu num_bytes %llu but there is no existing entry!",
 802                                   action, (unsigned long long)bytenr,
 803                                   (unsigned long long)num_bytes);
 804                         dump_ref_action(fs_info, ra);
 805                         kfree(ref);
 806                         kfree(ra);
 807                         goto out_unlock;
 808                 } else if (be->num_refs == 0) {
 809                         btrfs_err(fs_info,
 810                 "trying to do action %d for a bytenr that has 0 total references",
 811                                 action);
 812                         dump_block_entry(fs_info, be);
 813                         dump_ref_action(fs_info, ra);
 814                         kfree(ref);
 815                         kfree(ra);
 816                         goto out_unlock;
 817                 }
 818
 819                 if (!parent) {
 820                         tmp = insert_root_entry(&be->roots, re);
 821                         if (tmp) {
 822                                 kfree(re);
 823                                 re = tmp;
 824                         }
 825                 }
 826         }
 827
 828         exist = insert_ref_entry(&be->refs, ref);
 829         if (exist) {
 830                 if (action == BTRFS_DROP_DELAYED_REF) {
 831                         if (exist->num_refs == 0) {
 832                                 btrfs_err(fs_info,
 833 "dropping a ref for a existing root that doesn't have a ref on the 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                         exist->num_refs--;
 841                         if (exist->num_refs == 0) {
 842                                 rb_erase(&exist->node, &be->refs);
 843                                 kfree(exist);
 844                         }
 845                 } else if (!be->metadata) {
 846                         exist->num_refs++;
 847                 } else {
 848                         btrfs_err(fs_info,
 849 "attempting to add another ref for an existing ref on a tree block");
 850                         dump_block_entry(fs_info, be);
 851                         dump_ref_action(fs_info, ra);
 852                         kfree(ref);
 853                         kfree(ra);
 854                         goto out_unlock;
 855                 }
 856                 kfree(ref);
 857         } else {
 858                 if (action == BTRFS_DROP_DELAYED_REF) {
 859                         btrfs_err(fs_info,
 860 "dropping a ref for a root that doesn't have a ref on the block");
 861                         dump_block_entry(fs_info, be);
 862                         dump_ref_action(fs_info, ra);
 863                         kfree(ra);
 864                         goto out_unlock;
 865                 }
 866         }
 867
 868         if (!parent && !re) {
 869                 re = lookup_root_entry(&be->roots, ref_root);
 870                 if (!re) {
 871                         /*
 872                          * This shouldn't happen because we will add our re
 873                          * above when we lookup the be with !parent, but just in
 874                          * case catch this case so we don't panic because I
 875                          * didn't think of some other corner case.
 876                          */
 877                         btrfs_err(fs_info, "failed to find root %llu for %llu",
 878                                   generic_ref->real_root, be->bytenr);
 879                         dump_block_entry(fs_info, be);
 880                         dump_ref_action(fs_info, ra);
 881                         kfree(ra);
 882                         goto out_unlock;
 883                 }
 884         }
 885         if (action == BTRFS_DROP_DELAYED_REF) {
 886                 if (re)
 887                         re->num_refs--;
 888                 be->num_refs--;
 889         } else if (action == BTRFS_ADD_DELAYED_REF) {
 890                 be->num_refs++;
 891                 if (re)
 892                         re->num_refs++;
 893         }
 894         list_add_tail(&ra->list, &be->actions);
 895         ret = 0;
 896 out_unlock:
 897         spin_unlock(&fs_info->ref_verify_lock);
 898 out:
 899         if (ret)
 900                 btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
 901         return ret;
 902 }
 903
 904 /* Free up the ref cache */
 905 void btrfs_free_ref_cache(struct btrfs_fs_info *fs_info)
 906 {
 907         struct block_entry *be;
 908         struct rb_node *n;
 909
 910         if (!btrfs_test_opt(fs_info, REF_VERIFY))
 911                 return;
 912
 913         spin_lock(&fs_info->ref_verify_lock);
 914         while ((n = rb_first(&fs_info->block_tree))) {
 915                 be = rb_entry(n, struct block_entry, node);
 916                 rb_erase(&be->node, &fs_info->block_tree);
 917                 free_block_entry(be);
 918                 cond_resched_lock(&fs_info->ref_verify_lock);
 919         }
 920         spin_unlock(&fs_info->ref_verify_lock);
 921 }
 922
 923 void btrfs_free_ref_tree_range(struct btrfs_fs_info *fs_info, u64 start,
 924                                u64 len)
 925 {
 926         struct block_entry *be = NULL, *entry;
 927         struct rb_node *n;
 928
 929         if (!btrfs_test_opt(fs_info, REF_VERIFY))
 930                 return;
 931
 932         spin_lock(&fs_info->ref_verify_lock);
 933         n = fs_info->block_tree.rb_node;
 934         while (n) {
 935                 entry = rb_entry(n, struct block_entry, node);
 936                 if (entry->bytenr < start) {
 937                         n = n->rb_right;
 938                 } else if (entry->bytenr > start) {
 939                         n = n->rb_left;
 940                 } else {
 941                         be = entry;
 942                         break;
 943                 }
 944                 /* We want to get as close to start as possible */
 945                 if (be == NULL ||
 946                     (entry->bytenr < start && be->bytenr > start) ||
 947                     (entry->bytenr < start && entry->bytenr > be->bytenr))
 948                         be = entry;
 949         }
 950
 951         /*
 952          * Could have an empty block group, maybe have something to check for
 953          * this case to verify we were actually empty?
 954          */
 955         if (!be) {
 956                 spin_unlock(&fs_info->ref_verify_lock);
 957                 return;
 958         }
 959
 960         n = &be->node;
 961         while (n) {
 962                 be = rb_entry(n, struct block_entry, node);
 963                 n = rb_next(n);
 964                 if (be->bytenr < start && be->bytenr + be->len > start) {
 965                         btrfs_err(fs_info,
 966                                 "block entry overlaps a block group [%llu,%llu]!",
 967                                 start, len);
 968                         dump_block_entry(fs_info, be);
 969                         continue;
 970                 }
 971                 if (be->bytenr < start)
 972                         continue;
 973                 if (be->bytenr >= start + len)
 974                         break;
 975                 if (be->bytenr + be->len > start + len) {
 976                         btrfs_err(fs_info,
 977                                 "block entry overlaps a block group [%llu,%llu]!",
 978                                 start, len);
 979                         dump_block_entry(fs_info, be);
 980                 }
 981                 rb_erase(&be->node, &fs_info->block_tree);
 982                 free_block_entry(be);
 983         }
 984         spin_unlock(&fs_info->ref_verify_lock);
 985 }
 986
 987 /* Walk down all roots and build the ref tree, meant to be called at mount */
 988 int btrfs_build_ref_tree(struct btrfs_fs_info *fs_info)
 989 {
 990         struct btrfs_path *path;
 991         struct extent_buffer *eb;
 992         u64 bytenr = 0, num_bytes = 0;
 993         int ret, level;
 994
 995         if (!btrfs_test_opt(fs_info, REF_VERIFY))
 996                 return 0;
 997
 998         path = btrfs_alloc_path();
 999         if (!path)
1000                 return -ENOMEM;
1001
1002         eb = btrfs_read_lock_root_node(fs_info->extent_root);
1003         btrfs_set_lock_blocking_read(eb);
1004         level = btrfs_header_level(eb);
1005         path->nodes[level] = eb;
1006         path->slots[level] = 0;
1007         path->locks[level] = BTRFS_READ_LOCK_BLOCKING;
1008
1009         while (1) {
1010                 /*
1011                  * We have to keep track of the bytenr/num_bytes we last hit
1012                  * because we could have run out of space for an inline ref, and
1013                  * would have had to added a ref key item which may appear on a
1014                  * different leaf from the original extent item.
1015                  */
1016                 ret = walk_down_tree(fs_info->extent_root, path, level,
1017                                      &bytenr, &num_bytes);
1018                 if (ret)
1019                         break;
1020                 ret = walk_up_tree(path, &level);
1021                 if (ret < 0)
1022                         break;
1023                 if (ret > 0) {
1024                         ret = 0;
1025                         break;
1026                 }
1027         }
1028         if (ret) {
1029                 btrfs_clear_opt(fs_info->mount_opt, REF_VERIFY);
1030                 btrfs_free_ref_cache(fs_info);
1031         }
1032         btrfs_free_path(path);
1033         return ret;
1034 }