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