fs/btrfs/ctree.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007,2008 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/sched.h>
   7 #include <linux/slab.h>
   8 #include <linux/rbtree.h>
   9 #include <linux/mm.h>
  10 #include "ctree.h"
  11 #include "disk-io.h"
  12 #include "transaction.h"
  13 #include "print-tree.h"
  14 #include "locking.h"
  15 #include "volumes.h"
  16 #include "qgroup.h"
  17 #include "tree-mod-log.h"
  18
  19 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  20                       *root, struct btrfs_path *path, int level);
  21 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  22                       const struct btrfs_key *ins_key, struct btrfs_path *path,
  23                       int data_size, int extend);
  24 static int push_node_left(struct btrfs_trans_handle *trans,
  25                           struct extent_buffer *dst,
  26                           struct extent_buffer *src, int empty);
  27 static int balance_node_right(struct btrfs_trans_handle *trans,
  28                               struct extent_buffer *dst_buf,
  29                               struct extent_buffer *src_buf);
  30 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
  31                     int level, int slot);
  32
  33 static const struct btrfs_csums {
  34         u16             size;
  35         const char      name[10];
  36         const char      driver[12];
  37 } btrfs_csums[] = {
  38         [BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
  39         [BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
  40         [BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
  41         [BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
  42                                      .driver = "blake2b-256" },
  43 };
  44
  45 int btrfs_super_csum_size(const struct btrfs_super_block *s)
  46 {
  47         u16 t = btrfs_super_csum_type(s);
  48         /*
  49          * csum type is validated at mount time
  50          */
  51         return btrfs_csums[t].size;
  52 }
  53
  54 const char *btrfs_super_csum_name(u16 csum_type)
  55 {
  56         /* csum type is validated at mount time */
  57         return btrfs_csums[csum_type].name;
  58 }
  59
  60 /*
  61  * Return driver name if defined, otherwise the name that's also a valid driver
  62  * name
  63  */
  64 const char *btrfs_super_csum_driver(u16 csum_type)
  65 {
  66         /* csum type is validated at mount time */
  67         return btrfs_csums[csum_type].driver[0] ?
  68                 btrfs_csums[csum_type].driver :
  69                 btrfs_csums[csum_type].name;
  70 }
  71
  72 size_t __attribute_const__ btrfs_get_num_csums(void)
  73 {
  74         return ARRAY_SIZE(btrfs_csums);
  75 }
  76
  77 struct btrfs_path *btrfs_alloc_path(void)
  78 {
  79         return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
  80 }
  81
  82 /* this also releases the path */
  83 void btrfs_free_path(struct btrfs_path *p)
  84 {
  85         if (!p)
  86                 return;
  87         btrfs_release_path(p);
  88         kmem_cache_free(btrfs_path_cachep, p);
  89 }
  90
  91 /*
  92  * path release drops references on the extent buffers in the path
  93  * and it drops any locks held by this path
  94  *
  95  * It is safe to call this on paths that no locks or extent buffers held.
  96  */
  97 noinline void btrfs_release_path(struct btrfs_path *p)
  98 {
  99         int i;
 100
 101         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
 102                 p->slots[i] = 0;
 103                 if (!p->nodes[i])
 104                         continue;
 105                 if (p->locks[i]) {
 106                         btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
 107                         p->locks[i] = 0;
 108                 }
 109                 free_extent_buffer(p->nodes[i]);
 110                 p->nodes[i] = NULL;
 111         }
 112 }
 113
 114 /*
 115  * safely gets a reference on the root node of a tree.  A lock
 116  * is not taken, so a concurrent writer may put a different node
 117  * at the root of the tree.  See btrfs_lock_root_node for the
 118  * looping required.
 119  *
 120  * The extent buffer returned by this has a reference taken, so
 121  * it won't disappear.  It may stop being the root of the tree
 122  * at any time because there are no locks held.
 123  */
 124 struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
 125 {
 126         struct extent_buffer *eb;
 127
 128         while (1) {
 129                 rcu_read_lock();
 130                 eb = rcu_dereference(root->node);
 131
 132                 /*
 133                  * RCU really hurts here, we could free up the root node because
 134                  * it was COWed but we may not get the new root node yet so do
 135                  * the inc_not_zero dance and if it doesn't work then
 136                  * synchronize_rcu and try again.
 137                  */
 138                 if (atomic_inc_not_zero(&eb->refs)) {
 139                         rcu_read_unlock();
 140                         break;
 141                 }
 142                 rcu_read_unlock();
 143                 synchronize_rcu();
 144         }
 145         return eb;
 146 }
 147
 148 /*
 149  * Cowonly root (not-shareable trees, everything not subvolume or reloc roots),
 150  * just get put onto a simple dirty list.  Transaction walks this list to make
 151  * sure they get properly updated on disk.
 152  */
 153 static void add_root_to_dirty_list(struct btrfs_root *root)
 154 {
 155         struct btrfs_fs_info *fs_info = root->fs_info;
 156
 157         if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
 158             !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
 159                 return;
 160
 161         spin_lock(&fs_info->trans_lock);
 162         if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
 163                 /* Want the extent tree to be the last on the list */
 164                 if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID)
 165                         list_move_tail(&root->dirty_list,
 166                                        &fs_info->dirty_cowonly_roots);
 167                 else
 168                         list_move(&root->dirty_list,
 169                                   &fs_info->dirty_cowonly_roots);
 170         }
 171         spin_unlock(&fs_info->trans_lock);
 172 }
 173
 174 /*
 175  * used by snapshot creation to make a copy of a root for a tree with
 176  * a given objectid.  The buffer with the new root node is returned in
 177  * cow_ret, and this func returns zero on success or a negative error code.
 178  */
 179 int btrfs_copy_root(struct btrfs_trans_handle *trans,
 180                       struct btrfs_root *root,
 181                       struct extent_buffer *buf,
 182                       struct extent_buffer **cow_ret, u64 new_root_objectid)
 183 {
 184         struct btrfs_fs_info *fs_info = root->fs_info;
 185         struct extent_buffer *cow;
 186         int ret = 0;
 187         int level;
 188         struct btrfs_disk_key disk_key;
 189
 190         WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 191                 trans->transid != fs_info->running_transaction->transid);
 192         WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 193                 trans->transid != root->last_trans);
 194
 195         level = btrfs_header_level(buf);
 196         if (level == 0)
 197                 btrfs_item_key(buf, &disk_key, 0);
 198         else
 199                 btrfs_node_key(buf, &disk_key, 0);
 200
 201         cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
 202                                      &disk_key, level, buf->start, 0,
 203                                      BTRFS_NESTING_NEW_ROOT);
 204         if (IS_ERR(cow))
 205                 return PTR_ERR(cow);
 206
 207         copy_extent_buffer_full(cow, buf);
 208         btrfs_set_header_bytenr(cow, cow->start);
 209         btrfs_set_header_generation(cow, trans->transid);
 210         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 211         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 212                                      BTRFS_HEADER_FLAG_RELOC);
 213         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 214                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 215         else
 216                 btrfs_set_header_owner(cow, new_root_objectid);
 217
 218         write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
 219
 220         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 221         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 222                 ret = btrfs_inc_ref(trans, root, cow, 1);
 223         else
 224                 ret = btrfs_inc_ref(trans, root, cow, 0);
 225         if (ret) {
 226                 btrfs_tree_unlock(cow);
 227                 free_extent_buffer(cow);
 228                 btrfs_abort_transaction(trans, ret);
 229                 return ret;
 230         }
 231
 232         btrfs_mark_buffer_dirty(cow);
 233         *cow_ret = cow;
 234         return 0;
 235 }
 236
 237 /*
 238  * check if the tree block can be shared by multiple trees
 239  */
 240 int btrfs_block_can_be_shared(struct btrfs_root *root,
 241                               struct extent_buffer *buf)
 242 {
 243         /*
 244          * Tree blocks not in shareable trees and tree roots are never shared.
 245          * If a block was allocated after the last snapshot and the block was
 246          * not allocated by tree relocation, we know the block is not shared.
 247          */
 248         if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 249             buf != root->node && buf != root->commit_root &&
 250             (btrfs_header_generation(buf) <=
 251              btrfs_root_last_snapshot(&root->root_item) ||
 252              btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 253                 return 1;
 254
 255         return 0;
 256 }
 257
 258 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 259                                        struct btrfs_root *root,
 260                                        struct extent_buffer *buf,
 261                                        struct extent_buffer *cow,
 262                                        int *last_ref)
 263 {
 264         struct btrfs_fs_info *fs_info = root->fs_info;
 265         u64 refs;
 266         u64 owner;
 267         u64 flags;
 268         u64 new_flags = 0;
 269         int ret;
 270
 271         /*
 272          * Backrefs update rules:
 273          *
 274          * Always use full backrefs for extent pointers in tree block
 275          * allocated by tree relocation.
 276          *
 277          * If a shared tree block is no longer referenced by its owner
 278          * tree (btrfs_header_owner(buf) == root->root_key.objectid),
 279          * use full backrefs for extent pointers in tree block.
 280          *
 281          * If a tree block is been relocating
 282          * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
 283          * use full backrefs for extent pointers in tree block.
 284          * The reason for this is some operations (such as drop tree)
 285          * are only allowed for blocks use full backrefs.
 286          */
 287
 288         if (btrfs_block_can_be_shared(root, buf)) {
 289                 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
 290                                                btrfs_header_level(buf), 1,
 291                                                &refs, &flags);
 292                 if (ret)
 293                         return ret;
 294                 if (refs == 0) {
 295                         ret = -EROFS;
 296                         btrfs_handle_fs_error(fs_info, ret, NULL);
 297                         return ret;
 298                 }
 299         } else {
 300                 refs = 1;
 301                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 302                     btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 303                         flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
 304                 else
 305                         flags = 0;
 306         }
 307
 308         owner = btrfs_header_owner(buf);
 309         BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
 310                !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
 311
 312         if (refs > 1) {
 313                 if ((owner == root->root_key.objectid ||
 314                      root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
 315                     !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
 316                         ret = btrfs_inc_ref(trans, root, buf, 1);
 317                         if (ret)
 318                                 return ret;
 319
 320                         if (root->root_key.objectid ==
 321                             BTRFS_TREE_RELOC_OBJECTID) {
 322                                 ret = btrfs_dec_ref(trans, root, buf, 0);
 323                                 if (ret)
 324                                         return ret;
 325                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 326                                 if (ret)
 327                                         return ret;
 328                         }
 329                         new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
 330                 } else {
 331
 332                         if (root->root_key.objectid ==
 333                             BTRFS_TREE_RELOC_OBJECTID)
 334                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 335                         else
 336                                 ret = btrfs_inc_ref(trans, root, cow, 0);
 337                         if (ret)
 338                                 return ret;
 339                 }
 340                 if (new_flags != 0) {
 341                         int level = btrfs_header_level(buf);
 342
 343                         ret = btrfs_set_disk_extent_flags(trans, buf,
 344                                                           new_flags, level, 0);
 345                         if (ret)
 346                                 return ret;
 347                 }
 348         } else {
 349                 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
 350                         if (root->root_key.objectid ==
 351                             BTRFS_TREE_RELOC_OBJECTID)
 352                                 ret = btrfs_inc_ref(trans, root, cow, 1);
 353                         else
 354                                 ret = btrfs_inc_ref(trans, root, cow, 0);
 355                         if (ret)
 356                                 return ret;
 357                         ret = btrfs_dec_ref(trans, root, buf, 1);
 358                         if (ret)
 359                                 return ret;
 360                 }
 361                 btrfs_clean_tree_block(buf);
 362                 *last_ref = 1;
 363         }
 364         return 0;
 365 }
 366
 367 /*
 368  * does the dirty work in cow of a single block.  The parent block (if
 369  * supplied) is updated to point to the new cow copy.  The new buffer is marked
 370  * dirty and returned locked.  If you modify the block it needs to be marked
 371  * dirty again.
 372  *
 373  * search_start -- an allocation hint for the new block
 374  *
 375  * empty_size -- a hint that you plan on doing more cow.  This is the size in
 376  * bytes the allocator should try to find free next to the block it returns.
 377  * This is just a hint and may be ignored by the allocator.
 378  */
 379 static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 380                              struct btrfs_root *root,
 381                              struct extent_buffer *buf,
 382                              struct extent_buffer *parent, int parent_slot,
 383                              struct extent_buffer **cow_ret,
 384                              u64 search_start, u64 empty_size,
 385                              enum btrfs_lock_nesting nest)
 386 {
 387         struct btrfs_fs_info *fs_info = root->fs_info;
 388         struct btrfs_disk_key disk_key;
 389         struct extent_buffer *cow;
 390         int level, ret;
 391         int last_ref = 0;
 392         int unlock_orig = 0;
 393         u64 parent_start = 0;
 394
 395         if (*cow_ret == buf)
 396                 unlock_orig = 1;
 397
 398         btrfs_assert_tree_locked(buf);
 399
 400         WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 401                 trans->transid != fs_info->running_transaction->transid);
 402         WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 403                 trans->transid != root->last_trans);
 404
 405         level = btrfs_header_level(buf);
 406
 407         if (level == 0)
 408                 btrfs_item_key(buf, &disk_key, 0);
 409         else
 410                 btrfs_node_key(buf, &disk_key, 0);
 411
 412         if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
 413                 parent_start = parent->start;
 414
 415         cow = btrfs_alloc_tree_block(trans, root, parent_start,
 416                                      root->root_key.objectid, &disk_key, level,
 417                                      search_start, empty_size, nest);
 418         if (IS_ERR(cow))
 419                 return PTR_ERR(cow);
 420
 421         /* cow is set to blocking by btrfs_init_new_buffer */
 422
 423         copy_extent_buffer_full(cow, buf);
 424         btrfs_set_header_bytenr(cow, cow->start);
 425         btrfs_set_header_generation(cow, trans->transid);
 426         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 427         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 428                                      BTRFS_HEADER_FLAG_RELOC);
 429         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
 430                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 431         else
 432                 btrfs_set_header_owner(cow, root->root_key.objectid);
 433
 434         write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
 435
 436         ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
 437         if (ret) {
 438                 btrfs_tree_unlock(cow);
 439                 free_extent_buffer(cow);
 440                 btrfs_abort_transaction(trans, ret);
 441                 return ret;
 442         }
 443
 444         if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
 445                 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
 446                 if (ret) {
 447                         btrfs_tree_unlock(cow);
 448                         free_extent_buffer(cow);
 449                         btrfs_abort_transaction(trans, ret);
 450                         return ret;
 451                 }
 452         }
 453
 454         if (buf == root->node) {
 455                 WARN_ON(parent && parent != buf);
 456                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 457                     btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 458                         parent_start = buf->start;
 459
 460                 atomic_inc(&cow->refs);
 461                 ret = btrfs_tree_mod_log_insert_root(root->node, cow, true);
 462                 BUG_ON(ret < 0);
 463                 rcu_assign_pointer(root->node, cow);
 464
 465                 btrfs_free_tree_block(trans, root, buf, parent_start,
 466                                       last_ref);
 467                 free_extent_buffer(buf);
 468                 add_root_to_dirty_list(root);
 469         } else {
 470                 WARN_ON(trans->transid != btrfs_header_generation(parent));
 471                 btrfs_tree_mod_log_insert_key(parent, parent_slot,
 472                                               BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
 473                 btrfs_set_node_blockptr(parent, parent_slot,
 474                                         cow->start);
 475                 btrfs_set_node_ptr_generation(parent, parent_slot,
 476                                               trans->transid);
 477                 btrfs_mark_buffer_dirty(parent);
 478                 if (last_ref) {
 479                         ret = btrfs_tree_mod_log_free_eb(buf);
 480                         if (ret) {
 481                                 btrfs_tree_unlock(cow);
 482                                 free_extent_buffer(cow);
 483                                 btrfs_abort_transaction(trans, ret);
 484                                 return ret;
 485                         }
 486                 }
 487                 btrfs_free_tree_block(trans, root, buf, parent_start,
 488                                       last_ref);
 489         }
 490         if (unlock_orig)
 491                 btrfs_tree_unlock(buf);
 492         free_extent_buffer_stale(buf);
 493         btrfs_mark_buffer_dirty(cow);
 494         *cow_ret = cow;
 495         return 0;
 496 }
 497
 498 static inline int should_cow_block(struct btrfs_trans_handle *trans,
 499                                    struct btrfs_root *root,
 500                                    struct extent_buffer *buf)
 501 {
 502         if (btrfs_is_testing(root->fs_info))
 503                 return 0;
 504
 505         /* Ensure we can see the FORCE_COW bit */
 506         smp_mb__before_atomic();
 507
 508         /*
 509          * We do not need to cow a block if
 510          * 1) this block is not created or changed in this transaction;
 511          * 2) this block does not belong to TREE_RELOC tree;
 512          * 3) the root is not forced COW.
 513          *
 514          * What is forced COW:
 515          *    when we create snapshot during committing the transaction,
 516          *    after we've finished copying src root, we must COW the shared
 517          *    block to ensure the metadata consistency.
 518          */
 519         if (btrfs_header_generation(buf) == trans->transid &&
 520             !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
 521             !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
 522               btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
 523             !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
 524                 return 0;
 525         return 1;
 526 }
 527
 528 /*
 529  * cows a single block, see __btrfs_cow_block for the real work.
 530  * This version of it has extra checks so that a block isn't COWed more than
 531  * once per transaction, as long as it hasn't been written yet
 532  */
 533 noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
 534                     struct btrfs_root *root, struct extent_buffer *buf,
 535                     struct extent_buffer *parent, int parent_slot,
 536                     struct extent_buffer **cow_ret,
 537                     enum btrfs_lock_nesting nest)
 538 {
 539         struct btrfs_fs_info *fs_info = root->fs_info;
 540         u64 search_start;
 541         int ret;
 542
 543         if (test_bit(BTRFS_ROOT_DELETING, &root->state))
 544                 btrfs_err(fs_info,
 545                         "COW'ing blocks on a fs root that's being dropped");
 546
 547         if (trans->transaction != fs_info->running_transaction)
 548                 WARN(1, KERN_CRIT "trans %llu running %llu\n",
 549                        trans->transid,
 550                        fs_info->running_transaction->transid);
 551
 552         if (trans->transid != fs_info->generation)
 553                 WARN(1, KERN_CRIT "trans %llu running %llu\n",
 554                        trans->transid, fs_info->generation);
 555
 556         if (!should_cow_block(trans, root, buf)) {
 557                 *cow_ret = buf;
 558                 return 0;
 559         }
 560
 561         search_start = buf->start & ~((u64)SZ_1G - 1);
 562
 563         /*
 564          * Before CoWing this block for later modification, check if it's
 565          * the subtree root and do the delayed subtree trace if needed.
 566          *
 567          * Also We don't care about the error, as it's handled internally.
 568          */
 569         btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
 570         ret = __btrfs_cow_block(trans, root, buf, parent,
 571                                  parent_slot, cow_ret, search_start, 0, nest);
 572
 573         trace_btrfs_cow_block(root, buf, *cow_ret);
 574
 575         return ret;
 576 }
 577 ALLOW_ERROR_INJECTION(btrfs_cow_block, ERRNO);
 578
 579 /*
 580  * helper function for defrag to decide if two blocks pointed to by a
 581  * node are actually close by
 582  */
 583 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
 584 {
 585         if (blocknr < other && other - (blocknr + blocksize) < 32768)
 586                 return 1;
 587         if (blocknr > other && blocknr - (other + blocksize) < 32768)
 588                 return 1;
 589         return 0;
 590 }
 591
 592 #ifdef __LITTLE_ENDIAN
 593
 594 /*
 595  * Compare two keys, on little-endian the disk order is same as CPU order and
 596  * we can avoid the conversion.
 597  */
 598 static int comp_keys(const struct btrfs_disk_key *disk_key,
 599                      const struct btrfs_key *k2)
 600 {
 601         const struct btrfs_key *k1 = (const struct btrfs_key *)disk_key;
 602
 603         return btrfs_comp_cpu_keys(k1, k2);
 604 }
 605
 606 #else
 607
 608 /*
 609  * compare two keys in a memcmp fashion
 610  */
 611 static int comp_keys(const struct btrfs_disk_key *disk,
 612                      const struct btrfs_key *k2)
 613 {
 614         struct btrfs_key k1;
 615
 616         btrfs_disk_key_to_cpu(&k1, disk);
 617
 618         return btrfs_comp_cpu_keys(&k1, k2);
 619 }
 620 #endif
 621
 622 /*
 623  * same as comp_keys only with two btrfs_key's
 624  */
 625 int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
 626 {
 627         if (k1->objectid > k2->objectid)
 628                 return 1;
 629         if (k1->objectid < k2->objectid)
 630                 return -1;
 631         if (k1->type > k2->type)
 632                 return 1;
 633         if (k1->type < k2->type)
 634                 return -1;
 635         if (k1->offset > k2->offset)
 636                 return 1;
 637         if (k1->offset < k2->offset)
 638                 return -1;
 639         return 0;
 640 }
 641
 642 /*
 643  * this is used by the defrag code to go through all the
 644  * leaves pointed to by a node and reallocate them so that
 645  * disk order is close to key order
 646  */
 647 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 648                        struct btrfs_root *root, struct extent_buffer *parent,
 649                        int start_slot, u64 *last_ret,
 650                        struct btrfs_key *progress)
 651 {
 652         struct btrfs_fs_info *fs_info = root->fs_info;
 653         struct extent_buffer *cur;
 654         u64 blocknr;
 655         u64 search_start = *last_ret;
 656         u64 last_block = 0;
 657         u64 other;
 658         u32 parent_nritems;
 659         int end_slot;
 660         int i;
 661         int err = 0;
 662         u32 blocksize;
 663         int progress_passed = 0;
 664         struct btrfs_disk_key disk_key;
 665
 666         WARN_ON(trans->transaction != fs_info->running_transaction);
 667         WARN_ON(trans->transid != fs_info->generation);
 668
 669         parent_nritems = btrfs_header_nritems(parent);
 670         blocksize = fs_info->nodesize;
 671         end_slot = parent_nritems - 1;
 672
 673         if (parent_nritems <= 1)
 674                 return 0;
 675
 676         for (i = start_slot; i <= end_slot; i++) {
 677                 int close = 1;
 678
 679                 btrfs_node_key(parent, &disk_key, i);
 680                 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
 681                         continue;
 682
 683                 progress_passed = 1;
 684                 blocknr = btrfs_node_blockptr(parent, i);
 685                 if (last_block == 0)
 686                         last_block = blocknr;
 687
 688                 if (i > 0) {
 689                         other = btrfs_node_blockptr(parent, i - 1);
 690                         close = close_blocks(blocknr, other, blocksize);
 691                 }
 692                 if (!close && i < end_slot) {
 693                         other = btrfs_node_blockptr(parent, i + 1);
 694                         close = close_blocks(blocknr, other, blocksize);
 695                 }
 696                 if (close) {
 697                         last_block = blocknr;
 698                         continue;
 699                 }
 700
 701                 cur = btrfs_read_node_slot(parent, i);
 702                 if (IS_ERR(cur))
 703                         return PTR_ERR(cur);
 704                 if (search_start == 0)
 705                         search_start = last_block;
 706
 707                 btrfs_tree_lock(cur);
 708                 err = __btrfs_cow_block(trans, root, cur, parent, i,
 709                                         &cur, search_start,
 710                                         min(16 * blocksize,
 711                                             (end_slot - i) * blocksize),
 712                                         BTRFS_NESTING_COW);
 713                 if (err) {
 714                         btrfs_tree_unlock(cur);
 715                         free_extent_buffer(cur);
 716                         break;
 717                 }
 718                 search_start = cur->start;
 719                 last_block = cur->start;
 720                 *last_ret = search_start;
 721                 btrfs_tree_unlock(cur);
 722                 free_extent_buffer(cur);
 723         }
 724         return err;
 725 }
 726
 727 /*
 728  * search for key in the extent_buffer.  The items start at offset p,
 729  * and they are item_size apart.
 730  *
 731  * the slot in the array is returned via slot, and it points to
 732  * the place where you would insert key if it is not found in
 733  * the array.
 734  *
 735  * Slot may point to total number of items if the key is bigger than
 736  * all of the keys
 737  */
 738 static noinline int generic_bin_search(struct extent_buffer *eb,
 739                                        unsigned long p, int item_size,
 740                                        const struct btrfs_key *key, int *slot)
 741 {
 742         int low = 0;
 743         int high = btrfs_header_nritems(eb);
 744         int ret;
 745         const int key_size = sizeof(struct btrfs_disk_key);
 746
 747         if (low > high) {
 748                 btrfs_err(eb->fs_info,
 749                  "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
 750                           __func__, low, high, eb->start,
 751                           btrfs_header_owner(eb), btrfs_header_level(eb));
 752                 return -EINVAL;
 753         }
 754
 755         while (low < high) {
 756                 unsigned long oip;
 757                 unsigned long offset;
 758                 struct btrfs_disk_key *tmp;
 759                 struct btrfs_disk_key unaligned;
 760                 int mid;
 761
 762                 mid = (low + high) / 2;
 763                 offset = p + mid * item_size;
 764                 oip = offset_in_page(offset);
 765
 766                 if (oip + key_size <= PAGE_SIZE) {
 767                         const unsigned long idx = get_eb_page_index(offset);
 768                         char *kaddr = page_address(eb->pages[idx]);
 769
 770                         oip = get_eb_offset_in_page(eb, offset);
 771                         tmp = (struct btrfs_disk_key *)(kaddr + oip);
 772                 } else {
 773                         read_extent_buffer(eb, &unaligned, offset, key_size);
 774                         tmp = &unaligned;
 775                 }
 776
 777                 ret = comp_keys(tmp, key);
 778
 779                 if (ret < 0)
 780                         low = mid + 1;
 781                 else if (ret > 0)
 782                         high = mid;
 783                 else {
 784                         *slot = mid;
 785                         return 0;
 786                 }
 787         }
 788         *slot = low;
 789         return 1;
 790 }
 791
 792 /*
 793  * simple bin_search frontend that does the right thing for
 794  * leaves vs nodes
 795  */
 796 int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
 797                      int *slot)
 798 {
 799         if (btrfs_header_level(eb) == 0)
 800                 return generic_bin_search(eb,
 801                                           offsetof(struct btrfs_leaf, items),
 802                                           sizeof(struct btrfs_item), key, slot);
 803         else
 804                 return generic_bin_search(eb,
 805                                           offsetof(struct btrfs_node, ptrs),
 806                                           sizeof(struct btrfs_key_ptr), key, slot);
 807 }
 808
 809 static void root_add_used(struct btrfs_root *root, u32 size)
 810 {
 811         spin_lock(&root->accounting_lock);
 812         btrfs_set_root_used(&root->root_item,
 813                             btrfs_root_used(&root->root_item) + size);
 814         spin_unlock(&root->accounting_lock);
 815 }
 816
 817 static void root_sub_used(struct btrfs_root *root, u32 size)
 818 {
 819         spin_lock(&root->accounting_lock);
 820         btrfs_set_root_used(&root->root_item,
 821                             btrfs_root_used(&root->root_item) - size);
 822         spin_unlock(&root->accounting_lock);
 823 }
 824
 825 /* given a node and slot number, this reads the blocks it points to.  The
 826  * extent buffer is returned with a reference taken (but unlocked).
 827  */
 828 struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
 829                                            int slot)
 830 {
 831         int level = btrfs_header_level(parent);
 832         struct extent_buffer *eb;
 833         struct btrfs_key first_key;
 834
 835         if (slot < 0 || slot >= btrfs_header_nritems(parent))
 836                 return ERR_PTR(-ENOENT);
 837
 838         BUG_ON(level == 0);
 839
 840         btrfs_node_key_to_cpu(parent, &first_key, slot);
 841         eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
 842                              btrfs_header_owner(parent),
 843                              btrfs_node_ptr_generation(parent, slot),
 844                              level - 1, &first_key);
 845         if (!IS_ERR(eb) && !extent_buffer_uptodate(eb)) {
 846                 free_extent_buffer(eb);
 847                 eb = ERR_PTR(-EIO);
 848         }
 849
 850         return eb;
 851 }
 852
 853 /*
 854  * node level balancing, used to make sure nodes are in proper order for
 855  * item deletion.  We balance from the top down, so we have to make sure
 856  * that a deletion won't leave an node completely empty later on.
 857  */
 858 static noinline int balance_level(struct btrfs_trans_handle *trans,
 859                          struct btrfs_root *root,
 860                          struct btrfs_path *path, int level)
 861 {
 862         struct btrfs_fs_info *fs_info = root->fs_info;
 863         struct extent_buffer *right = NULL;
 864         struct extent_buffer *mid;
 865         struct extent_buffer *left = NULL;
 866         struct extent_buffer *parent = NULL;
 867         int ret = 0;
 868         int wret;
 869         int pslot;
 870         int orig_slot = path->slots[level];
 871         u64 orig_ptr;
 872
 873         ASSERT(level > 0);
 874
 875         mid = path->nodes[level];
 876
 877         WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK);
 878         WARN_ON(btrfs_header_generation(mid) != trans->transid);
 879
 880         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 881
 882         if (level < BTRFS_MAX_LEVEL - 1) {
 883                 parent = path->nodes[level + 1];
 884                 pslot = path->slots[level + 1];
 885         }
 886
 887         /*
 888          * deal with the case where there is only one pointer in the root
 889          * by promoting the node below to a root
 890          */
 891         if (!parent) {
 892                 struct extent_buffer *child;
 893
 894                 if (btrfs_header_nritems(mid) != 1)
 895                         return 0;
 896
 897                 /* promote the child to a root */
 898                 child = btrfs_read_node_slot(mid, 0);
 899                 if (IS_ERR(child)) {
 900                         ret = PTR_ERR(child);
 901                         btrfs_handle_fs_error(fs_info, ret, NULL);
 902                         goto enospc;
 903                 }
 904
 905                 btrfs_tree_lock(child);
 906                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child,
 907                                       BTRFS_NESTING_COW);
 908                 if (ret) {
 909                         btrfs_tree_unlock(child);
 910                         free_extent_buffer(child);
 911                         goto enospc;
 912                 }
 913
 914                 ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
 915                 BUG_ON(ret < 0);
 916                 rcu_assign_pointer(root->node, child);
 917
 918                 add_root_to_dirty_list(root);
 919                 btrfs_tree_unlock(child);
 920
 921                 path->locks[level] = 0;
 922                 path->nodes[level] = NULL;
 923                 btrfs_clean_tree_block(mid);
 924                 btrfs_tree_unlock(mid);
 925                 /* once for the path */
 926                 free_extent_buffer(mid);
 927
 928                 root_sub_used(root, mid->len);
 929                 btrfs_free_tree_block(trans, root, mid, 0, 1);
 930                 /* once for the root ptr */
 931                 free_extent_buffer_stale(mid);
 932                 return 0;
 933         }
 934         if (btrfs_header_nritems(mid) >
 935             BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
 936                 return 0;
 937
 938         left = btrfs_read_node_slot(parent, pslot - 1);
 939         if (IS_ERR(left))
 940                 left = NULL;
 941
 942         if (left) {
 943                 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
 944                 wret = btrfs_cow_block(trans, root, left,
 945                                        parent, pslot - 1, &left,
 946                                        BTRFS_NESTING_LEFT_COW);
 947                 if (wret) {
 948                         ret = wret;
 949                         goto enospc;
 950                 }
 951         }
 952
 953         right = btrfs_read_node_slot(parent, pslot + 1);
 954         if (IS_ERR(right))
 955                 right = NULL;
 956
 957         if (right) {
 958                 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
 959                 wret = btrfs_cow_block(trans, root, right,
 960                                        parent, pslot + 1, &right,
 961                                        BTRFS_NESTING_RIGHT_COW);
 962                 if (wret) {
 963                         ret = wret;
 964                         goto enospc;
 965                 }
 966         }
 967
 968         /* first, try to make some room in the middle buffer */
 969         if (left) {
 970                 orig_slot += btrfs_header_nritems(left);
 971                 wret = push_node_left(trans, left, mid, 1);
 972                 if (wret < 0)
 973                         ret = wret;
 974         }
 975
 976         /*
 977          * then try to empty the right most buffer into the middle
 978          */
 979         if (right) {
 980                 wret = push_node_left(trans, mid, right, 1);
 981                 if (wret < 0 && wret != -ENOSPC)
 982                         ret = wret;
 983                 if (btrfs_header_nritems(right) == 0) {
 984                         btrfs_clean_tree_block(right);
 985                         btrfs_tree_unlock(right);
 986                         del_ptr(root, path, level + 1, pslot + 1);
 987                         root_sub_used(root, right->len);
 988                         btrfs_free_tree_block(trans, root, right, 0, 1);
 989                         free_extent_buffer_stale(right);
 990                         right = NULL;
 991                 } else {
 992                         struct btrfs_disk_key right_key;
 993                         btrfs_node_key(right, &right_key, 0);
 994                         ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
 995                                         BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
 996                         BUG_ON(ret < 0);
 997                         btrfs_set_node_key(parent, &right_key, pslot + 1);
 998                         btrfs_mark_buffer_dirty(parent);
 999                 }
1000         }
1001         if (btrfs_header_nritems(mid) == 1) {
1002                 /*
1003                  * we're not allowed to leave a node with one item in the
1004                  * tree during a delete.  A deletion from lower in the tree
1005                  * could try to delete the only pointer in this node.
1006                  * So, pull some keys from the left.
1007                  * There has to be a left pointer at this point because
1008                  * otherwise we would have pulled some pointers from the
1009                  * right
1010                  */
1011                 if (!left) {
1012                         ret = -EROFS;
1013                         btrfs_handle_fs_error(fs_info, ret, NULL);
1014                         goto enospc;
1015                 }
1016                 wret = balance_node_right(trans, mid, left);
1017                 if (wret < 0) {
1018                         ret = wret;
1019                         goto enospc;
1020                 }
1021                 if (wret == 1) {
1022                         wret = push_node_left(trans, left, mid, 1);
1023                         if (wret < 0)
1024                                 ret = wret;
1025                 }
1026                 BUG_ON(wret == 1);
1027         }
1028         if (btrfs_header_nritems(mid) == 0) {
1029                 btrfs_clean_tree_block(mid);
1030                 btrfs_tree_unlock(mid);
1031                 del_ptr(root, path, level + 1, pslot);
1032                 root_sub_used(root, mid->len);
1033                 btrfs_free_tree_block(trans, root, mid, 0, 1);
1034                 free_extent_buffer_stale(mid);
1035                 mid = NULL;
1036         } else {
1037                 /* update the parent key to reflect our changes */
1038                 struct btrfs_disk_key mid_key;
1039                 btrfs_node_key(mid, &mid_key, 0);
1040                 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1041                                 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1042                 BUG_ON(ret < 0);
1043                 btrfs_set_node_key(parent, &mid_key, pslot);
1044                 btrfs_mark_buffer_dirty(parent);
1045         }
1046
1047         /* update the path */
1048         if (left) {
1049                 if (btrfs_header_nritems(left) > orig_slot) {
1050                         atomic_inc(&left->refs);
1051                         /* left was locked after cow */
1052                         path->nodes[level] = left;
1053                         path->slots[level + 1] -= 1;
1054                         path->slots[level] = orig_slot;
1055                         if (mid) {
1056                                 btrfs_tree_unlock(mid);
1057                                 free_extent_buffer(mid);
1058                         }
1059                 } else {
1060                         orig_slot -= btrfs_header_nritems(left);
1061                         path->slots[level] = orig_slot;
1062                 }
1063         }
1064         /* double check we haven't messed things up */
1065         if (orig_ptr !=
1066             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1067                 BUG();
1068 enospc:
1069         if (right) {
1070                 btrfs_tree_unlock(right);
1071                 free_extent_buffer(right);
1072         }
1073         if (left) {
1074                 if (path->nodes[level] != left)
1075                         btrfs_tree_unlock(left);
1076                 free_extent_buffer(left);
1077         }
1078         return ret;
1079 }
1080
1081 /* Node balancing for insertion.  Here we only split or push nodes around
1082  * when they are completely full.  This is also done top down, so we
1083  * have to be pessimistic.
1084  */
1085 static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1086                                           struct btrfs_root *root,
1087                                           struct btrfs_path *path, int level)
1088 {
1089         struct btrfs_fs_info *fs_info = root->fs_info;
1090         struct extent_buffer *right = NULL;
1091         struct extent_buffer *mid;
1092         struct extent_buffer *left = NULL;
1093         struct extent_buffer *parent = NULL;
1094         int ret = 0;
1095         int wret;
1096         int pslot;
1097         int orig_slot = path->slots[level];
1098
1099         if (level == 0)
1100                 return 1;
1101
1102         mid = path->nodes[level];
1103         WARN_ON(btrfs_header_generation(mid) != trans->transid);
1104
1105         if (level < BTRFS_MAX_LEVEL - 1) {
1106                 parent = path->nodes[level + 1];
1107                 pslot = path->slots[level + 1];
1108         }
1109
1110         if (!parent)
1111                 return 1;
1112
1113         left = btrfs_read_node_slot(parent, pslot - 1);
1114         if (IS_ERR(left))
1115                 left = NULL;
1116
1117         /* first, try to make some room in the middle buffer */
1118         if (left) {
1119                 u32 left_nr;
1120
1121                 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
1122
1123                 left_nr = btrfs_header_nritems(left);
1124                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1125                         wret = 1;
1126                 } else {
1127                         ret = btrfs_cow_block(trans, root, left, parent,
1128                                               pslot - 1, &left,
1129                                               BTRFS_NESTING_LEFT_COW);
1130                         if (ret)
1131                                 wret = 1;
1132                         else {
1133                                 wret = push_node_left(trans, left, mid, 0);
1134                         }
1135                 }
1136                 if (wret < 0)
1137                         ret = wret;
1138                 if (wret == 0) {
1139                         struct btrfs_disk_key disk_key;
1140                         orig_slot += left_nr;
1141                         btrfs_node_key(mid, &disk_key, 0);
1142                         ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1143                                         BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1144                         BUG_ON(ret < 0);
1145                         btrfs_set_node_key(parent, &disk_key, pslot);
1146                         btrfs_mark_buffer_dirty(parent);
1147                         if (btrfs_header_nritems(left) > orig_slot) {
1148                                 path->nodes[level] = left;
1149                                 path->slots[level + 1] -= 1;
1150                                 path->slots[level] = orig_slot;
1151                                 btrfs_tree_unlock(mid);
1152                                 free_extent_buffer(mid);
1153                         } else {
1154                                 orig_slot -=
1155                                         btrfs_header_nritems(left);
1156                                 path->slots[level] = orig_slot;
1157                                 btrfs_tree_unlock(left);
1158                                 free_extent_buffer(left);
1159                         }
1160                         return 0;
1161                 }
1162                 btrfs_tree_unlock(left);
1163                 free_extent_buffer(left);
1164         }
1165         right = btrfs_read_node_slot(parent, pslot + 1);
1166         if (IS_ERR(right))
1167                 right = NULL;
1168
1169         /*
1170          * then try to empty the right most buffer into the middle
1171          */
1172         if (right) {
1173                 u32 right_nr;
1174
1175                 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
1176
1177                 right_nr = btrfs_header_nritems(right);
1178                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1179                         wret = 1;
1180                 } else {
1181                         ret = btrfs_cow_block(trans, root, right,
1182                                               parent, pslot + 1,
1183                                               &right, BTRFS_NESTING_RIGHT_COW);
1184                         if (ret)
1185                                 wret = 1;
1186                         else {
1187                                 wret = balance_node_right(trans, right, mid);
1188                         }
1189                 }
1190                 if (wret < 0)
1191                         ret = wret;
1192                 if (wret == 0) {
1193                         struct btrfs_disk_key disk_key;
1194
1195                         btrfs_node_key(right, &disk_key, 0);
1196                         ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1197                                         BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1198                         BUG_ON(ret < 0);
1199                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
1200                         btrfs_mark_buffer_dirty(parent);
1201
1202                         if (btrfs_header_nritems(mid) <= orig_slot) {
1203                                 path->nodes[level] = right;
1204                                 path->slots[level + 1] += 1;
1205                                 path->slots[level] = orig_slot -
1206                                         btrfs_header_nritems(mid);
1207                                 btrfs_tree_unlock(mid);
1208                                 free_extent_buffer(mid);
1209                         } else {
1210                                 btrfs_tree_unlock(right);
1211                                 free_extent_buffer(right);
1212                         }
1213                         return 0;
1214                 }
1215                 btrfs_tree_unlock(right);
1216                 free_extent_buffer(right);
1217         }
1218         return 1;
1219 }
1220
1221 /*
1222  * readahead one full node of leaves, finding things that are close
1223  * to the block in 'slot', and triggering ra on them.
1224  */
1225 static void reada_for_search(struct btrfs_fs_info *fs_info,
1226                              struct btrfs_path *path,
1227                              int level, int slot, u64 objectid)
1228 {
1229         struct extent_buffer *node;
1230         struct btrfs_disk_key disk_key;
1231         u32 nritems;
1232         u64 search;
1233         u64 target;
1234         u64 nread = 0;
1235         u64 nread_max;
1236         struct extent_buffer *eb;
1237         u32 nr;
1238         u32 blocksize;
1239         u32 nscan = 0;
1240
1241         if (level != 1 && path->reada != READA_FORWARD_ALWAYS)
1242                 return;
1243
1244         if (!path->nodes[level])
1245                 return;
1246
1247         node = path->nodes[level];
1248
1249         /*
1250          * Since the time between visiting leaves is much shorter than the time
1251          * between visiting nodes, limit read ahead of nodes to 1, to avoid too
1252          * much IO at once (possibly random).
1253          */
1254         if (path->reada == READA_FORWARD_ALWAYS) {
1255                 if (level > 1)
1256                         nread_max = node->fs_info->nodesize;
1257                 else
1258                         nread_max = SZ_128K;
1259         } else {
1260                 nread_max = SZ_64K;
1261         }
1262
1263         search = btrfs_node_blockptr(node, slot);
1264         blocksize = fs_info->nodesize;
1265         eb = find_extent_buffer(fs_info, search);
1266         if (eb) {
1267                 free_extent_buffer(eb);
1268                 return;
1269         }
1270
1271         target = search;
1272
1273         nritems = btrfs_header_nritems(node);
1274         nr = slot;
1275
1276         while (1) {
1277                 if (path->reada == READA_BACK) {
1278                         if (nr == 0)
1279                                 break;
1280                         nr--;
1281                 } else if (path->reada == READA_FORWARD ||
1282                            path->reada == READA_FORWARD_ALWAYS) {
1283                         nr++;
1284                         if (nr >= nritems)
1285                                 break;
1286                 }
1287                 if (path->reada == READA_BACK && objectid) {
1288                         btrfs_node_key(node, &disk_key, nr);
1289                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
1290                                 break;
1291                 }
1292                 search = btrfs_node_blockptr(node, nr);
1293                 if (path->reada == READA_FORWARD_ALWAYS ||
1294                     (search <= target && target - search <= 65536) ||
1295                     (search > target && search - target <= 65536)) {
1296                         btrfs_readahead_node_child(node, nr);
1297                         nread += blocksize;
1298                 }
1299                 nscan++;
1300                 if (nread > nread_max || nscan > 32)
1301                         break;
1302         }
1303 }
1304
1305 static noinline void reada_for_balance(struct btrfs_path *path, int level)
1306 {
1307         struct extent_buffer *parent;
1308         int slot;
1309         int nritems;
1310
1311         parent = path->nodes[level + 1];
1312         if (!parent)
1313                 return;
1314
1315         nritems = btrfs_header_nritems(parent);
1316         slot = path->slots[level + 1];
1317
1318         if (slot > 0)
1319                 btrfs_readahead_node_child(parent, slot - 1);
1320         if (slot + 1 < nritems)
1321                 btrfs_readahead_node_child(parent, slot + 1);
1322 }
1323
1324
1325 /*
1326  * when we walk down the tree, it is usually safe to unlock the higher layers
1327  * in the tree.  The exceptions are when our path goes through slot 0, because
1328  * operations on the tree might require changing key pointers higher up in the
1329  * tree.
1330  *
1331  * callers might also have set path->keep_locks, which tells this code to keep
1332  * the lock if the path points to the last slot in the block.  This is part of
1333  * walking through the tree, and selecting the next slot in the higher block.
1334  *
1335  * lowest_unlock sets the lowest level in the tree we're allowed to unlock.  so
1336  * if lowest_unlock is 1, level 0 won't be unlocked
1337  */
1338 static noinline void unlock_up(struct btrfs_path *path, int level,
1339                                int lowest_unlock, int min_write_lock_level,
1340                                int *write_lock_level)
1341 {
1342         int i;
1343         int skip_level = level;
1344         int no_skips = 0;
1345         struct extent_buffer *t;
1346
1347         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1348                 if (!path->nodes[i])
1349                         break;
1350                 if (!path->locks[i])
1351                         break;
1352                 if (!no_skips && path->slots[i] == 0) {
1353                         skip_level = i + 1;
1354                         continue;
1355                 }
1356                 if (!no_skips && path->keep_locks) {
1357                         u32 nritems;
1358                         t = path->nodes[i];
1359                         nritems = btrfs_header_nritems(t);
1360                         if (nritems < 1 || path->slots[i] >= nritems - 1) {
1361                                 skip_level = i + 1;
1362                                 continue;
1363                         }
1364                 }
1365                 if (skip_level < i && i >= lowest_unlock)
1366                         no_skips = 1;
1367
1368                 t = path->nodes[i];
1369                 if (i >= lowest_unlock && i > skip_level) {
1370                         btrfs_tree_unlock_rw(t, path->locks[i]);
1371                         path->locks[i] = 0;
1372                         if (write_lock_level &&
1373                             i > min_write_lock_level &&
1374                             i <= *write_lock_level) {
1375                                 *write_lock_level = i - 1;
1376                         }
1377                 }
1378         }
1379 }
1380
1381 /*
1382  * helper function for btrfs_search_slot.  The goal is to find a block
1383  * in cache without setting the path to blocking.  If we find the block
1384  * we return zero and the path is unchanged.
1385  *
1386  * If we can't find the block, we set the path blocking and do some
1387  * reada.  -EAGAIN is returned and the search must be repeated.
1388  */
1389 static int
1390 read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
1391                       struct extent_buffer **eb_ret, int level, int slot,
1392                       const struct btrfs_key *key)
1393 {
1394         struct btrfs_fs_info *fs_info = root->fs_info;
1395         u64 blocknr;
1396         u64 gen;
1397         struct extent_buffer *tmp;
1398         struct btrfs_key first_key;
1399         int ret;
1400         int parent_level;
1401
1402         blocknr = btrfs_node_blockptr(*eb_ret, slot);
1403         gen = btrfs_node_ptr_generation(*eb_ret, slot);
1404         parent_level = btrfs_header_level(*eb_ret);
1405         btrfs_node_key_to_cpu(*eb_ret, &first_key, slot);
1406
1407         tmp = find_extent_buffer(fs_info, blocknr);
1408         if (tmp) {
1409                 if (p->reada == READA_FORWARD_ALWAYS)
1410                         reada_for_search(fs_info, p, level, slot, key->objectid);
1411
1412                 /* first we do an atomic uptodate check */
1413                 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
1414                         /*
1415                          * Do extra check for first_key, eb can be stale due to
1416                          * being cached, read from scrub, or have multiple
1417                          * parents (shared tree blocks).
1418                          */
1419                         if (btrfs_verify_level_key(tmp,
1420                                         parent_level - 1, &first_key, gen)) {
1421                                 free_extent_buffer(tmp);
1422                                 return -EUCLEAN;
1423                         }
1424                         *eb_ret = tmp;
1425                         return 0;
1426                 }
1427
1428                 /* now we're allowed to do a blocking uptodate check */
1429                 ret = btrfs_read_buffer(tmp, gen, parent_level - 1, &first_key);
1430                 if (!ret) {
1431                         *eb_ret = tmp;
1432                         return 0;
1433                 }
1434                 free_extent_buffer(tmp);
1435                 btrfs_release_path(p);
1436                 return -EIO;
1437         }
1438
1439         /*
1440          * reduce lock contention at high levels
1441          * of the btree by dropping locks before
1442          * we read.  Don't release the lock on the current
1443          * level because we need to walk this node to figure
1444          * out which blocks to read.
1445          */
1446         btrfs_unlock_up_safe(p, level + 1);
1447
1448         if (p->reada != READA_NONE)
1449                 reada_for_search(fs_info, p, level, slot, key->objectid);
1450
1451         ret = -EAGAIN;
1452         tmp = read_tree_block(fs_info, blocknr, root->root_key.objectid,
1453                               gen, parent_level - 1, &first_key);
1454         if (!IS_ERR(tmp)) {
1455                 /*
1456                  * If the read above didn't mark this buffer up to date,
1457                  * it will never end up being up to date.  Set ret to EIO now
1458                  * and give up so that our caller doesn't loop forever
1459                  * on our EAGAINs.
1460                  */
1461                 if (!extent_buffer_uptodate(tmp))
1462                         ret = -EIO;
1463                 free_extent_buffer(tmp);
1464         } else {
1465                 ret = PTR_ERR(tmp);
1466         }
1467
1468         btrfs_release_path(p);
1469         return ret;
1470 }
1471
1472 /*
1473  * helper function for btrfs_search_slot.  This does all of the checks
1474  * for node-level blocks and does any balancing required based on
1475  * the ins_len.
1476  *
1477  * If no extra work was required, zero is returned.  If we had to
1478  * drop the path, -EAGAIN is returned and btrfs_search_slot must
1479  * start over
1480  */
1481 static int
1482 setup_nodes_for_search(struct btrfs_trans_handle *trans,
1483                        struct btrfs_root *root, struct btrfs_path *p,
1484                        struct extent_buffer *b, int level, int ins_len,
1485                        int *write_lock_level)
1486 {
1487         struct btrfs_fs_info *fs_info = root->fs_info;
1488         int ret = 0;
1489
1490         if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
1491             BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
1492
1493                 if (*write_lock_level < level + 1) {
1494                         *write_lock_level = level + 1;
1495                         btrfs_release_path(p);
1496                         return -EAGAIN;
1497                 }
1498
1499                 reada_for_balance(p, level);
1500                 ret = split_node(trans, root, p, level);
1501
1502                 b = p->nodes[level];
1503         } else if (ins_len < 0 && btrfs_header_nritems(b) <
1504                    BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
1505
1506                 if (*write_lock_level < level + 1) {
1507                         *write_lock_level = level + 1;
1508                         btrfs_release_path(p);
1509                         return -EAGAIN;
1510                 }
1511
1512                 reada_for_balance(p, level);
1513                 ret = balance_level(trans, root, p, level);
1514                 if (ret)
1515                         return ret;
1516
1517                 b = p->nodes[level];
1518                 if (!b) {
1519                         btrfs_release_path(p);
1520                         return -EAGAIN;
1521                 }
1522                 BUG_ON(btrfs_header_nritems(b) == 1);
1523         }
1524         return ret;
1525 }
1526
1527 int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
1528                 u64 iobjectid, u64 ioff, u8 key_type,
1529                 struct btrfs_key *found_key)
1530 {
1531         int ret;
1532         struct btrfs_key key;
1533         struct extent_buffer *eb;
1534
1535         ASSERT(path);
1536         ASSERT(found_key);
1537
1538         key.type = key_type;
1539         key.objectid = iobjectid;
1540         key.offset = ioff;
1541
1542         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1543         if (ret < 0)
1544                 return ret;
1545
1546         eb = path->nodes[0];
1547         if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1548                 ret = btrfs_next_leaf(fs_root, path);
1549                 if (ret)
1550                         return ret;
1551                 eb = path->nodes[0];
1552         }
1553
1554         btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1555         if (found_key->type != key.type ||
1556                         found_key->objectid != key.objectid)
1557                 return 1;
1558
1559         return 0;
1560 }
1561
1562 static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
1563                                                         struct btrfs_path *p,
1564                                                         int write_lock_level)
1565 {
1566         struct btrfs_fs_info *fs_info = root->fs_info;
1567         struct extent_buffer *b;
1568         int root_lock;
1569         int level = 0;
1570
1571         /* We try very hard to do read locks on the root */
1572         root_lock = BTRFS_READ_LOCK;
1573
1574         if (p->search_commit_root) {
1575                 /*
1576                  * The commit roots are read only so we always do read locks,
1577                  * and we always must hold the commit_root_sem when doing
1578                  * searches on them, the only exception is send where we don't
1579                  * want to block transaction commits for a long time, so
1580                  * we need to clone the commit root in order to avoid races
1581                  * with transaction commits that create a snapshot of one of
1582                  * the roots used by a send operation.
1583                  */
1584                 if (p->need_commit_sem) {
1585                         down_read(&fs_info->commit_root_sem);
1586                         b = btrfs_clone_extent_buffer(root->commit_root);
1587                         up_read(&fs_info->commit_root_sem);
1588                         if (!b)
1589                                 return ERR_PTR(-ENOMEM);
1590
1591                 } else {
1592                         b = root->commit_root;
1593                         atomic_inc(&b->refs);
1594                 }
1595                 level = btrfs_header_level(b);
1596                 /*
1597                  * Ensure that all callers have set skip_locking when
1598                  * p->search_commit_root = 1.
1599                  */
1600                 ASSERT(p->skip_locking == 1);
1601
1602                 goto out;
1603         }
1604
1605         if (p->skip_locking) {
1606                 b = btrfs_root_node(root);
1607                 level = btrfs_header_level(b);
1608                 goto out;
1609         }
1610
1611         /*
1612          * If the level is set to maximum, we can skip trying to get the read
1613          * lock.
1614          */
1615         if (write_lock_level < BTRFS_MAX_LEVEL) {
1616                 /*
1617                  * We don't know the level of the root node until we actually
1618                  * have it read locked
1619                  */
1620                 b = btrfs_read_lock_root_node(root);
1621                 level = btrfs_header_level(b);
1622                 if (level > write_lock_level)
1623                         goto out;
1624
1625                 /* Whoops, must trade for write lock */
1626                 btrfs_tree_read_unlock(b);
1627                 free_extent_buffer(b);
1628         }
1629
1630         b = btrfs_lock_root_node(root);
1631         root_lock = BTRFS_WRITE_LOCK;
1632
1633         /* The level might have changed, check again */
1634         level = btrfs_header_level(b);
1635
1636 out:
1637         p->nodes[level] = b;
1638         if (!p->skip_locking)
1639                 p->locks[level] = root_lock;
1640         /*
1641          * Callers are responsible for dropping b's references.
1642          */
1643         return b;
1644 }
1645
1646
1647 /*
1648  * btrfs_search_slot - look for a key in a tree and perform necessary
1649  * modifications to preserve tree invariants.
1650  *
1651  * @trans:      Handle of transaction, used when modifying the tree
1652  * @p:          Holds all btree nodes along the search path
1653  * @root:       The root node of the tree
1654  * @key:        The key we are looking for
1655  * @ins_len:    Indicates purpose of search:
1656  *              >0  for inserts it's size of item inserted (*)
1657  *              <0  for deletions
1658  *               0  for plain searches, not modifying the tree
1659  *
1660  *              (*) If size of item inserted doesn't include
1661  *              sizeof(struct btrfs_item), then p->search_for_extension must
1662  *              be set.
1663  * @cow:        boolean should CoW operations be performed. Must always be 1
1664  *              when modifying the tree.
1665  *
1666  * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
1667  * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
1668  *
1669  * If @key is found, 0 is returned and you can find the item in the leaf level
1670  * of the path (level 0)
1671  *
1672  * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
1673  * points to the slot where it should be inserted
1674  *
1675  * If an error is encountered while searching the tree a negative error number
1676  * is returned
1677  */
1678 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1679                       const struct btrfs_key *key, struct btrfs_path *p,
1680                       int ins_len, int cow)
1681 {
1682         struct extent_buffer *b;
1683         int slot;
1684         int ret;
1685         int err;
1686         int level;
1687         int lowest_unlock = 1;
1688         /* everything at write_lock_level or lower must be write locked */
1689         int write_lock_level = 0;
1690         u8 lowest_level = 0;
1691         int min_write_lock_level;
1692         int prev_cmp;
1693
1694         lowest_level = p->lowest_level;
1695         WARN_ON(lowest_level && ins_len > 0);
1696         WARN_ON(p->nodes[0] != NULL);
1697         BUG_ON(!cow && ins_len);
1698
1699         if (ins_len < 0) {
1700                 lowest_unlock = 2;
1701
1702                 /* when we are removing items, we might have to go up to level
1703                  * two as we update tree pointers  Make sure we keep write
1704                  * for those levels as well
1705                  */
1706                 write_lock_level = 2;
1707         } else if (ins_len > 0) {
1708                 /*
1709                  * for inserting items, make sure we have a write lock on
1710                  * level 1 so we can update keys
1711                  */
1712                 write_lock_level = 1;
1713         }
1714
1715         if (!cow)
1716                 write_lock_level = -1;
1717
1718         if (cow && (p->keep_locks || p->lowest_level))
1719                 write_lock_level = BTRFS_MAX_LEVEL;
1720
1721         min_write_lock_level = write_lock_level;
1722
1723 again:
1724         prev_cmp = -1;
1725         b = btrfs_search_slot_get_root(root, p, write_lock_level);
1726         if (IS_ERR(b)) {
1727                 ret = PTR_ERR(b);
1728                 goto done;
1729         }
1730
1731         while (b) {
1732                 int dec = 0;
1733
1734                 level = btrfs_header_level(b);
1735
1736                 if (cow) {
1737                         bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
1738
1739                         /*
1740                          * if we don't really need to cow this block
1741                          * then we don't want to set the path blocking,
1742                          * so we test it here
1743                          */
1744                         if (!should_cow_block(trans, root, b))
1745                                 goto cow_done;
1746
1747                         /*
1748                          * must have write locks on this node and the
1749                          * parent
1750                          */
1751                         if (level > write_lock_level ||
1752                             (level + 1 > write_lock_level &&
1753                             level + 1 < BTRFS_MAX_LEVEL &&
1754                             p->nodes[level + 1])) {
1755                                 write_lock_level = level + 1;
1756                                 btrfs_release_path(p);
1757                                 goto again;
1758                         }
1759
1760                         if (last_level)
1761                                 err = btrfs_cow_block(trans, root, b, NULL, 0,
1762                                                       &b,
1763                                                       BTRFS_NESTING_COW);
1764                         else
1765                                 err = btrfs_cow_block(trans, root, b,
1766                                                       p->nodes[level + 1],
1767                                                       p->slots[level + 1], &b,
1768                                                       BTRFS_NESTING_COW);
1769                         if (err) {
1770                                 ret = err;
1771                                 goto done;
1772                         }
1773                 }
1774 cow_done:
1775                 p->nodes[level] = b;
1776                 /*
1777                  * Leave path with blocking locks to avoid massive
1778                  * lock context switch, this is made on purpose.
1779                  */
1780
1781                 /*
1782                  * we have a lock on b and as long as we aren't changing
1783                  * the tree, there is no way to for the items in b to change.
1784                  * It is safe to drop the lock on our parent before we
1785                  * go through the expensive btree search on b.
1786                  *
1787                  * If we're inserting or deleting (ins_len != 0), then we might
1788                  * be changing slot zero, which may require changing the parent.
1789                  * So, we can't drop the lock until after we know which slot
1790                  * we're operating on.
1791                  */
1792                 if (!ins_len && !p->keep_locks) {
1793                         int u = level + 1;
1794
1795                         if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
1796                                 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
1797                                 p->locks[u] = 0;
1798                         }
1799                 }
1800
1801                 /*
1802                  * If btrfs_bin_search returns an exact match (prev_cmp == 0)
1803                  * we can safely assume the target key will always be in slot 0
1804                  * on lower levels due to the invariants BTRFS' btree provides,
1805                  * namely that a btrfs_key_ptr entry always points to the
1806                  * lowest key in the child node, thus we can skip searching
1807                  * lower levels
1808                  */
1809                 if (prev_cmp == 0) {
1810                         slot = 0;
1811                         ret = 0;
1812                 } else {
1813                         ret = btrfs_bin_search(b, key, &slot);
1814                         prev_cmp = ret;
1815                         if (ret < 0)
1816                                 goto done;
1817                 }
1818
1819                 if (level == 0) {
1820                         p->slots[level] = slot;
1821                         /*
1822                          * Item key already exists. In this case, if we are
1823                          * allowed to insert the item (for example, in dir_item
1824                          * case, item key collision is allowed), it will be
1825                          * merged with the original item. Only the item size
1826                          * grows, no new btrfs item will be added. If
1827                          * search_for_extension is not set, ins_len already
1828                          * accounts the size btrfs_item, deduct it here so leaf
1829                          * space check will be correct.
1830                          */
1831                         if (ret == 0 && ins_len > 0 && !p->search_for_extension) {
1832                                 ASSERT(ins_len >= sizeof(struct btrfs_item));
1833                                 ins_len -= sizeof(struct btrfs_item);
1834                         }
1835                         if (ins_len > 0 &&
1836                             btrfs_leaf_free_space(b) < ins_len) {
1837                                 if (write_lock_level < 1) {
1838                                         write_lock_level = 1;
1839                                         btrfs_release_path(p);
1840                                         goto again;
1841                                 }
1842
1843                                 err = split_leaf(trans, root, key,
1844                                                  p, ins_len, ret == 0);
1845
1846                                 BUG_ON(err > 0);
1847                                 if (err) {
1848                                         ret = err;
1849                                         goto done;
1850                                 }
1851                         }
1852                         if (!p->search_for_split)
1853                                 unlock_up(p, level, lowest_unlock,
1854                                           min_write_lock_level, NULL);
1855                         goto done;
1856                 }
1857                 if (ret && slot > 0) {
1858                         dec = 1;
1859                         slot--;
1860                 }
1861                 p->slots[level] = slot;
1862                 err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
1863                                              &write_lock_level);
1864                 if (err == -EAGAIN)
1865                         goto again;
1866                 if (err) {
1867                         ret = err;
1868                         goto done;
1869                 }
1870                 b = p->nodes[level];
1871                 slot = p->slots[level];
1872
1873                 /*
1874                  * Slot 0 is special, if we change the key we have to update
1875                  * the parent pointer which means we must have a write lock on
1876                  * the parent
1877                  */
1878                 if (slot == 0 && ins_len && write_lock_level < level + 1) {
1879                         write_lock_level = level + 1;
1880                         btrfs_release_path(p);
1881                         goto again;
1882                 }
1883
1884                 unlock_up(p, level, lowest_unlock, min_write_lock_level,
1885                           &write_lock_level);
1886
1887                 if (level == lowest_level) {
1888                         if (dec)
1889                                 p->slots[level]++;
1890                         goto done;
1891                 }
1892
1893                 err = read_block_for_search(root, p, &b, level, slot, key);
1894                 if (err == -EAGAIN)
1895                         goto again;
1896                 if (err) {
1897                         ret = err;
1898                         goto done;
1899                 }
1900
1901                 if (!p->skip_locking) {
1902                         level = btrfs_header_level(b);
1903                         if (level <= write_lock_level) {
1904                                 btrfs_tree_lock(b);
1905                                 p->locks[level] = BTRFS_WRITE_LOCK;
1906                         } else {
1907                                 btrfs_tree_read_lock(b);
1908                                 p->locks[level] = BTRFS_READ_LOCK;
1909                         }
1910                         p->nodes[level] = b;
1911                 }
1912         }
1913         ret = 1;
1914 done:
1915         if (ret < 0 && !p->skip_release_on_error)
1916                 btrfs_release_path(p);
1917         return ret;
1918 }
1919 ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO);
1920
1921 /*
1922  * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
1923  * current state of the tree together with the operations recorded in the tree
1924  * modification log to search for the key in a previous version of this tree, as
1925  * denoted by the time_seq parameter.
1926  *
1927  * Naturally, there is no support for insert, delete or cow operations.
1928  *
1929  * The resulting path and return value will be set up as if we called
1930  * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
1931  */
1932 int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
1933                           struct btrfs_path *p, u64 time_seq)
1934 {
1935         struct btrfs_fs_info *fs_info = root->fs_info;
1936         struct extent_buffer *b;
1937         int slot;
1938         int ret;
1939         int err;
1940         int level;
1941         int lowest_unlock = 1;
1942         u8 lowest_level = 0;
1943
1944         lowest_level = p->lowest_level;
1945         WARN_ON(p->nodes[0] != NULL);
1946
1947         if (p->search_commit_root) {
1948                 BUG_ON(time_seq);
1949                 return btrfs_search_slot(NULL, root, key, p, 0, 0);
1950         }
1951
1952 again:
1953         b = btrfs_get_old_root(root, time_seq);
1954         if (!b) {
1955                 ret = -EIO;
1956                 goto done;
1957         }
1958         level = btrfs_header_level(b);
1959         p->locks[level] = BTRFS_READ_LOCK;
1960
1961         while (b) {
1962                 int dec = 0;
1963
1964                 level = btrfs_header_level(b);
1965                 p->nodes[level] = b;
1966
1967                 /*
1968                  * we have a lock on b and as long as we aren't changing
1969                  * the tree, there is no way to for the items in b to change.
1970                  * It is safe to drop the lock on our parent before we
1971                  * go through the expensive btree search on b.
1972                  */
1973                 btrfs_unlock_up_safe(p, level + 1);
1974
1975                 ret = btrfs_bin_search(b, key, &slot);
1976                 if (ret < 0)
1977                         goto done;
1978
1979                 if (level == 0) {
1980                         p->slots[level] = slot;
1981                         unlock_up(p, level, lowest_unlock, 0, NULL);
1982                         goto done;
1983                 }
1984
1985                 if (ret && slot > 0) {
1986                         dec = 1;
1987                         slot--;
1988                 }
1989                 p->slots[level] = slot;
1990                 unlock_up(p, level, lowest_unlock, 0, NULL);
1991
1992                 if (level == lowest_level) {
1993                         if (dec)
1994                                 p->slots[level]++;
1995                         goto done;
1996                 }
1997
1998                 err = read_block_for_search(root, p, &b, level, slot, key);
1999                 if (err == -EAGAIN)
2000                         goto again;
2001                 if (err) {
2002                         ret = err;
2003                         goto done;
2004                 }
2005
2006                 level = btrfs_header_level(b);
2007                 btrfs_tree_read_lock(b);
2008                 b = btrfs_tree_mod_log_rewind(fs_info, p, b, time_seq);
2009                 if (!b) {
2010                         ret = -ENOMEM;
2011                         goto done;
2012                 }
2013                 p->locks[level] = BTRFS_READ_LOCK;
2014                 p->nodes[level] = b;
2015         }
2016         ret = 1;
2017 done:
2018         if (ret < 0)
2019                 btrfs_release_path(p);
2020
2021         return ret;
2022 }
2023
2024 /*
2025  * helper to use instead of search slot if no exact match is needed but
2026  * instead the next or previous item should be returned.
2027  * When find_higher is true, the next higher item is returned, the next lower
2028  * otherwise.
2029  * When return_any and find_higher are both true, and no higher item is found,
2030  * return the next lower instead.
2031  * When return_any is true and find_higher is false, and no lower item is found,
2032  * return the next higher instead.
2033  * It returns 0 if any item is found, 1 if none is found (tree empty), and
2034  * < 0 on error
2035  */
2036 int btrfs_search_slot_for_read(struct btrfs_root *root,
2037                                const struct btrfs_key *key,
2038                                struct btrfs_path *p, int find_higher,
2039                                int return_any)
2040 {
2041         int ret;
2042         struct extent_buffer *leaf;
2043
2044 again:
2045         ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
2046         if (ret <= 0)
2047                 return ret;
2048         /*
2049          * a return value of 1 means the path is at the position where the
2050          * item should be inserted. Normally this is the next bigger item,
2051          * but in case the previous item is the last in a leaf, path points
2052          * to the first free slot in the previous leaf, i.e. at an invalid
2053          * item.
2054          */
2055         leaf = p->nodes[0];
2056
2057         if (find_higher) {
2058                 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
2059                         ret = btrfs_next_leaf(root, p);
2060                         if (ret <= 0)
2061                                 return ret;
2062                         if (!return_any)
2063                                 return 1;
2064                         /*
2065                          * no higher item found, return the next
2066                          * lower instead
2067                          */
2068                         return_any = 0;
2069                         find_higher = 0;
2070                         btrfs_release_path(p);
2071                         goto again;
2072                 }
2073         } else {
2074                 if (p->slots[0] == 0) {
2075                         ret = btrfs_prev_leaf(root, p);
2076                         if (ret < 0)
2077                                 return ret;
2078                         if (!ret) {
2079                                 leaf = p->nodes[0];
2080                                 if (p->slots[0] == btrfs_header_nritems(leaf))
2081                                         p->slots[0]--;
2082                                 return 0;
2083                         }
2084                         if (!return_any)
2085                                 return 1;
2086                         /*
2087                          * no lower item found, return the next
2088                          * higher instead
2089                          */
2090                         return_any = 0;
2091                         find_higher = 1;
2092                         btrfs_release_path(p);
2093                         goto again;
2094                 } else {
2095                         --p->slots[0];
2096                 }
2097         }
2098         return 0;
2099 }
2100
2101 /*
2102  * adjust the pointers going up the tree, starting at level
2103  * making sure the right key of each node is points to 'key'.
2104  * This is used after shifting pointers to the left, so it stops
2105  * fixing up pointers when a given leaf/node is not in slot 0 of the
2106  * higher levels
2107  *
2108  */
2109 static void fixup_low_keys(struct btrfs_path *path,
2110                            struct btrfs_disk_key *key, int level)
2111 {
2112         int i;
2113         struct extent_buffer *t;
2114         int ret;
2115
2116         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2117                 int tslot = path->slots[i];
2118
2119                 if (!path->nodes[i])
2120                         break;
2121                 t = path->nodes[i];
2122                 ret = btrfs_tree_mod_log_insert_key(t, tslot,
2123                                 BTRFS_MOD_LOG_KEY_REPLACE, GFP_ATOMIC);
2124                 BUG_ON(ret < 0);
2125                 btrfs_set_node_key(t, key, tslot);
2126                 btrfs_mark_buffer_dirty(path->nodes[i]);
2127                 if (tslot != 0)
2128                         break;
2129         }
2130 }
2131
2132 /*
2133  * update item key.
2134  *
2135  * This function isn't completely safe. It's the caller's responsibility
2136  * that the new key won't break the order
2137  */
2138 void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
2139                              struct btrfs_path *path,
2140                              const struct btrfs_key *new_key)
2141 {
2142         struct btrfs_disk_key disk_key;
2143         struct extent_buffer *eb;
2144         int slot;
2145
2146         eb = path->nodes[0];
2147         slot = path->slots[0];
2148         if (slot > 0) {
2149                 btrfs_item_key(eb, &disk_key, slot - 1);
2150                 if (unlikely(comp_keys(&disk_key, new_key) >= 0)) {
2151                         btrfs_crit(fs_info,
2152                 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2153                                    slot, btrfs_disk_key_objectid(&disk_key),
2154                                    btrfs_disk_key_type(&disk_key),
2155                                    btrfs_disk_key_offset(&disk_key),
2156                                    new_key->objectid, new_key->type,
2157                                    new_key->offset);
2158                         btrfs_print_leaf(eb);
2159                         BUG();
2160                 }
2161         }
2162         if (slot < btrfs_header_nritems(eb) - 1) {
2163                 btrfs_item_key(eb, &disk_key, slot + 1);
2164                 if (unlikely(comp_keys(&disk_key, new_key) <= 0)) {
2165                         btrfs_crit(fs_info,
2166                 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2167                                    slot, btrfs_disk_key_objectid(&disk_key),
2168                                    btrfs_disk_key_type(&disk_key),
2169                                    btrfs_disk_key_offset(&disk_key),
2170                                    new_key->objectid, new_key->type,
2171                                    new_key->offset);
2172                         btrfs_print_leaf(eb);
2173                         BUG();
2174                 }
2175         }
2176
2177         btrfs_cpu_key_to_disk(&disk_key, new_key);
2178         btrfs_set_item_key(eb, &disk_key, slot);
2179         btrfs_mark_buffer_dirty(eb);
2180         if (slot == 0)
2181                 fixup_low_keys(path, &disk_key, 1);
2182 }
2183
2184 /*
2185  * Check key order of two sibling extent buffers.
2186  *
2187  * Return true if something is wrong.
2188  * Return false if everything is fine.
2189  *
2190  * Tree-checker only works inside one tree block, thus the following
2191  * corruption can not be detected by tree-checker:
2192  *
2193  * Leaf @left                   | Leaf @right
2194  * --------------------------------------------------------------
2195  * | 1 | 2 | 3 | 4 | 5 | f6 |   | 7 | 8 |
2196  *
2197  * Key f6 in leaf @left itself is valid, but not valid when the next
2198  * key in leaf @right is 7.
2199  * This can only be checked at tree block merge time.
2200  * And since tree checker has ensured all key order in each tree block
2201  * is correct, we only need to bother the last key of @left and the first
2202  * key of @right.
2203  */
2204 static bool check_sibling_keys(struct extent_buffer *left,
2205                                struct extent_buffer *right)
2206 {
2207         struct btrfs_key left_last;
2208         struct btrfs_key right_first;
2209         int level = btrfs_header_level(left);
2210         int nr_left = btrfs_header_nritems(left);
2211         int nr_right = btrfs_header_nritems(right);
2212
2213         /* No key to check in one of the tree blocks */
2214         if (!nr_left || !nr_right)
2215                 return false;
2216
2217         if (level) {
2218                 btrfs_node_key_to_cpu(left, &left_last, nr_left - 1);
2219                 btrfs_node_key_to_cpu(right, &right_first, 0);
2220         } else {
2221                 btrfs_item_key_to_cpu(left, &left_last, nr_left - 1);
2222                 btrfs_item_key_to_cpu(right, &right_first, 0);
2223         }
2224
2225         if (btrfs_comp_cpu_keys(&left_last, &right_first) >= 0) {
2226                 btrfs_crit(left->fs_info,
2227 "bad key order, sibling blocks, left last (%llu %u %llu) right first (%llu %u %llu)",
2228                            left_last.objectid, left_last.type,
2229                            left_last.offset, right_first.objectid,
2230                            right_first.type, right_first.offset);
2231                 return true;
2232         }
2233         return false;
2234 }
2235
2236 /*
2237  * try to push data from one node into the next node left in the
2238  * tree.
2239  *
2240  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2241  * error, and > 0 if there was no room in the left hand block.
2242  */
2243 static int push_node_left(struct btrfs_trans_handle *trans,
2244                           struct extent_buffer *dst,
2245                           struct extent_buffer *src, int empty)
2246 {
2247         struct btrfs_fs_info *fs_info = trans->fs_info;
2248         int push_items = 0;
2249         int src_nritems;
2250         int dst_nritems;
2251         int ret = 0;
2252
2253         src_nritems = btrfs_header_nritems(src);
2254         dst_nritems = btrfs_header_nritems(dst);
2255         push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2256         WARN_ON(btrfs_header_generation(src) != trans->transid);
2257         WARN_ON(btrfs_header_generation(dst) != trans->transid);
2258
2259         if (!empty && src_nritems <= 8)
2260                 return 1;
2261
2262         if (push_items <= 0)
2263                 return 1;
2264
2265         if (empty) {
2266                 push_items = min(src_nritems, push_items);
2267                 if (push_items < src_nritems) {
2268                         /* leave at least 8 pointers in the node if
2269                          * we aren't going to empty it
2270                          */
2271                         if (src_nritems - push_items < 8) {
2272                                 if (push_items <= 8)
2273                                         return 1;
2274                                 push_items -= 8;
2275                         }
2276                 }
2277         } else
2278                 push_items = min(src_nritems - 8, push_items);
2279
2280         /* dst is the left eb, src is the middle eb */
2281         if (check_sibling_keys(dst, src)) {
2282                 ret = -EUCLEAN;
2283                 btrfs_abort_transaction(trans, ret);
2284                 return ret;
2285         }
2286         ret = btrfs_tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
2287         if (ret) {
2288                 btrfs_abort_transaction(trans, ret);
2289                 return ret;
2290         }
2291         copy_extent_buffer(dst, src,
2292                            btrfs_node_key_ptr_offset(dst_nritems),
2293                            btrfs_node_key_ptr_offset(0),
2294                            push_items * sizeof(struct btrfs_key_ptr));
2295
2296         if (push_items < src_nritems) {
2297                 /*
2298                  * Don't call btrfs_tree_mod_log_insert_move() here, key removal
2299                  * was already fully logged by btrfs_tree_mod_log_eb_copy() above.
2300                  */
2301                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
2302                                       btrfs_node_key_ptr_offset(push_items),
2303                                       (src_nritems - push_items) *
2304                                       sizeof(struct btrfs_key_ptr));
2305         }
2306         btrfs_set_header_nritems(src, src_nritems - push_items);
2307         btrfs_set_header_nritems(dst, dst_nritems + push_items);
2308         btrfs_mark_buffer_dirty(src);
2309         btrfs_mark_buffer_dirty(dst);
2310
2311         return ret;
2312 }
2313
2314 /*
2315  * try to push data from one node into the next node right in the
2316  * tree.
2317  *
2318  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
2319  * error, and > 0 if there was no room in the right hand block.
2320  *
2321  * this will  only push up to 1/2 the contents of the left node over
2322  */
2323 static int balance_node_right(struct btrfs_trans_handle *trans,
2324                               struct extent_buffer *dst,
2325                               struct extent_buffer *src)
2326 {
2327         struct btrfs_fs_info *fs_info = trans->fs_info;
2328         int push_items = 0;
2329         int max_push;
2330         int src_nritems;
2331         int dst_nritems;
2332         int ret = 0;
2333
2334         WARN_ON(btrfs_header_generation(src) != trans->transid);
2335         WARN_ON(btrfs_header_generation(dst) != trans->transid);
2336
2337         src_nritems = btrfs_header_nritems(src);
2338         dst_nritems = btrfs_header_nritems(dst);
2339         push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2340         if (push_items <= 0)
2341                 return 1;
2342
2343         if (src_nritems < 4)
2344                 return 1;
2345
2346         max_push = src_nritems / 2 + 1;
2347         /* don't try to empty the node */
2348         if (max_push >= src_nritems)
2349                 return 1;
2350
2351         if (max_push < push_items)
2352                 push_items = max_push;
2353
2354         /* dst is the right eb, src is the middle eb */
2355         if (check_sibling_keys(src, dst)) {
2356                 ret = -EUCLEAN;
2357                 btrfs_abort_transaction(trans, ret);
2358                 return ret;
2359         }
2360         ret = btrfs_tree_mod_log_insert_move(dst, push_items, 0, dst_nritems);
2361         BUG_ON(ret < 0);
2362         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
2363                                       btrfs_node_key_ptr_offset(0),
2364                                       (dst_nritems) *
2365                                       sizeof(struct btrfs_key_ptr));
2366
2367         ret = btrfs_tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
2368                                          push_items);
2369         if (ret) {
2370                 btrfs_abort_transaction(trans, ret);
2371                 return ret;
2372         }
2373         copy_extent_buffer(dst, src,
2374                            btrfs_node_key_ptr_offset(0),
2375                            btrfs_node_key_ptr_offset(src_nritems - push_items),
2376                            push_items * sizeof(struct btrfs_key_ptr));
2377
2378         btrfs_set_header_nritems(src, src_nritems - push_items);
2379         btrfs_set_header_nritems(dst, dst_nritems + push_items);
2380
2381         btrfs_mark_buffer_dirty(src);
2382         btrfs_mark_buffer_dirty(dst);
2383
2384         return ret;
2385 }
2386
2387 /*
2388  * helper function to insert a new root level in the tree.
2389  * A new node is allocated, and a single item is inserted to
2390  * point to the existing root
2391  *
2392  * returns zero on success or < 0 on failure.
2393  */
2394 static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2395                            struct btrfs_root *root,
2396                            struct btrfs_path *path, int level)
2397 {
2398         struct btrfs_fs_info *fs_info = root->fs_info;
2399         u64 lower_gen;
2400         struct extent_buffer *lower;
2401         struct extent_buffer *c;
2402         struct extent_buffer *old;
2403         struct btrfs_disk_key lower_key;
2404         int ret;
2405
2406         BUG_ON(path->nodes[level]);
2407         BUG_ON(path->nodes[level-1] != root->node);
2408
2409         lower = path->nodes[level-1];
2410         if (level == 1)
2411                 btrfs_item_key(lower, &lower_key, 0);
2412         else
2413                 btrfs_node_key(lower, &lower_key, 0);
2414
2415         c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
2416                                    &lower_key, level, root->node->start, 0,
2417                                    BTRFS_NESTING_NEW_ROOT);
2418         if (IS_ERR(c))
2419                 return PTR_ERR(c);
2420
2421         root_add_used(root, fs_info->nodesize);
2422
2423         btrfs_set_header_nritems(c, 1);
2424         btrfs_set_node_key(c, &lower_key, 0);
2425         btrfs_set_node_blockptr(c, 0, lower->start);
2426         lower_gen = btrfs_header_generation(lower);
2427         WARN_ON(lower_gen != trans->transid);
2428
2429         btrfs_set_node_ptr_generation(c, 0, lower_gen);
2430
2431         btrfs_mark_buffer_dirty(c);
2432
2433         old = root->node;
2434         ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
2435         BUG_ON(ret < 0);
2436         rcu_assign_pointer(root->node, c);
2437
2438         /* the super has an extra ref to root->node */
2439         free_extent_buffer(old);
2440
2441         add_root_to_dirty_list(root);
2442         atomic_inc(&c->refs);
2443         path->nodes[level] = c;
2444         path->locks[level] = BTRFS_WRITE_LOCK;
2445         path->slots[level] = 0;
2446         return 0;
2447 }
2448
2449 /*
2450  * worker function to insert a single pointer in a node.
2451  * the node should have enough room for the pointer already
2452  *
2453  * slot and level indicate where you want the key to go, and
2454  * blocknr is the block the key points to.
2455  */
2456 static void insert_ptr(struct btrfs_trans_handle *trans,
2457                        struct btrfs_path *path,
2458                        struct btrfs_disk_key *key, u64 bytenr,
2459                        int slot, int level)
2460 {
2461         struct extent_buffer *lower;
2462         int nritems;
2463         int ret;
2464
2465         BUG_ON(!path->nodes[level]);
2466         btrfs_assert_tree_locked(path->nodes[level]);
2467         lower = path->nodes[level];
2468         nritems = btrfs_header_nritems(lower);
2469         BUG_ON(slot > nritems);
2470         BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
2471         if (slot != nritems) {
2472                 if (level) {
2473                         ret = btrfs_tree_mod_log_insert_move(lower, slot + 1,
2474                                         slot, nritems - slot);
2475                         BUG_ON(ret < 0);
2476                 }
2477                 memmove_extent_buffer(lower,
2478                               btrfs_node_key_ptr_offset(slot + 1),
2479                               btrfs_node_key_ptr_offset(slot),
2480                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
2481         }
2482         if (level) {
2483                 ret = btrfs_tree_mod_log_insert_key(lower, slot,
2484                                             BTRFS_MOD_LOG_KEY_ADD, GFP_NOFS);
2485                 BUG_ON(ret < 0);
2486         }
2487         btrfs_set_node_key(lower, key, slot);
2488         btrfs_set_node_blockptr(lower, slot, bytenr);
2489         WARN_ON(trans->transid == 0);
2490         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
2491         btrfs_set_header_nritems(lower, nritems + 1);
2492         btrfs_mark_buffer_dirty(lower);
2493 }
2494
2495 /*
2496  * split the node at the specified level in path in two.
2497  * The path is corrected to point to the appropriate node after the split
2498  *
2499  * Before splitting this tries to make some room in the node by pushing
2500  * left and right, if either one works, it returns right away.
2501  *
2502  * returns 0 on success and < 0 on failure
2503  */
2504 static noinline int split_node(struct btrfs_trans_handle *trans,
2505                                struct btrfs_root *root,
2506                                struct btrfs_path *path, int level)
2507 {
2508         struct btrfs_fs_info *fs_info = root->fs_info;
2509         struct extent_buffer *c;
2510         struct extent_buffer *split;
2511         struct btrfs_disk_key disk_key;
2512         int mid;
2513         int ret;
2514         u32 c_nritems;
2515
2516         c = path->nodes[level];
2517         WARN_ON(btrfs_header_generation(c) != trans->transid);
2518         if (c == root->node) {
2519                 /*
2520                  * trying to split the root, lets make a new one
2521                  *
2522                  * tree mod log: We don't log_removal old root in
2523                  * insert_new_root, because that root buffer will be kept as a
2524                  * normal node. We are going to log removal of half of the
2525                  * elements below with btrfs_tree_mod_log_eb_copy(). We're
2526                  * holding a tree lock on the buffer, which is why we cannot
2527                  * race with other tree_mod_log users.
2528                  */
2529                 ret = insert_new_root(trans, root, path, level + 1);
2530                 if (ret)
2531                         return ret;
2532         } else {
2533                 ret = push_nodes_for_insert(trans, root, path, level);
2534                 c = path->nodes[level];
2535                 if (!ret && btrfs_header_nritems(c) <
2536                     BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
2537                         return 0;
2538                 if (ret < 0)
2539                         return ret;
2540         }
2541
2542         c_nritems = btrfs_header_nritems(c);
2543         mid = (c_nritems + 1) / 2;
2544         btrfs_node_key(c, &disk_key, mid);
2545
2546         split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
2547                                        &disk_key, level, c->start, 0,
2548                                        BTRFS_NESTING_SPLIT);
2549         if (IS_ERR(split))
2550                 return PTR_ERR(split);
2551
2552         root_add_used(root, fs_info->nodesize);
2553         ASSERT(btrfs_header_level(c) == level);
2554
2555         ret = btrfs_tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
2556         if (ret) {
2557                 btrfs_abort_transaction(trans, ret);
2558                 return ret;
2559         }
2560         copy_extent_buffer(split, c,
2561                            btrfs_node_key_ptr_offset(0),
2562                            btrfs_node_key_ptr_offset(mid),
2563                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
2564         btrfs_set_header_nritems(split, c_nritems - mid);
2565         btrfs_set_header_nritems(c, mid);
2566
2567         btrfs_mark_buffer_dirty(c);
2568         btrfs_mark_buffer_dirty(split);
2569
2570         insert_ptr(trans, path, &disk_key, split->start,
2571                    path->slots[level + 1] + 1, level + 1);
2572
2573         if (path->slots[level] >= mid) {
2574                 path->slots[level] -= mid;
2575                 btrfs_tree_unlock(c);
2576                 free_extent_buffer(c);
2577                 path->nodes[level] = split;
2578                 path->slots[level + 1] += 1;
2579         } else {
2580                 btrfs_tree_unlock(split);
2581                 free_extent_buffer(split);
2582         }
2583         return 0;
2584 }
2585
2586 /*
2587  * how many bytes are required to store the items in a leaf.  start
2588  * and nr indicate which items in the leaf to check.  This totals up the
2589  * space used both by the item structs and the item data
2590  */
2591 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
2592 {
2593         struct btrfs_item *start_item;
2594         struct btrfs_item *end_item;
2595         int data_len;
2596         int nritems = btrfs_header_nritems(l);
2597         int end = min(nritems, start + nr) - 1;
2598
2599         if (!nr)
2600                 return 0;
2601         start_item = btrfs_item_nr(start);
2602         end_item = btrfs_item_nr(end);
2603         data_len = btrfs_item_offset(l, start_item) +
2604                    btrfs_item_size(l, start_item);
2605         data_len = data_len - btrfs_item_offset(l, end_item);
2606         data_len += sizeof(struct btrfs_item) * nr;
2607         WARN_ON(data_len < 0);
2608         return data_len;
2609 }
2610
2611 /*
2612  * The space between the end of the leaf items and
2613  * the start of the leaf data.  IOW, how much room
2614  * the leaf has left for both items and data
2615  */
2616 noinline int btrfs_leaf_free_space(struct extent_buffer *leaf)
2617 {
2618         struct btrfs_fs_info *fs_info = leaf->fs_info;
2619         int nritems = btrfs_header_nritems(leaf);
2620         int ret;
2621
2622         ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
2623         if (ret < 0) {
2624                 btrfs_crit(fs_info,
2625                            "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
2626                            ret,
2627                            (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
2628                            leaf_space_used(leaf, 0, nritems), nritems);
2629         }
2630         return ret;
2631 }
2632
2633 /*
2634  * min slot controls the lowest index we're willing to push to the
2635  * right.  We'll push up to and including min_slot, but no lower
2636  */
2637 static noinline int __push_leaf_right(struct btrfs_path *path,
2638                                       int data_size, int empty,
2639                                       struct extent_buffer *right,
2640                                       int free_space, u32 left_nritems,
2641                                       u32 min_slot)
2642 {
2643         struct btrfs_fs_info *fs_info = right->fs_info;
2644         struct extent_buffer *left = path->nodes[0];
2645         struct extent_buffer *upper = path->nodes[1];
2646         struct btrfs_map_token token;
2647         struct btrfs_disk_key disk_key;
2648         int slot;
2649         u32 i;
2650         int push_space = 0;
2651         int push_items = 0;
2652         struct btrfs_item *item;
2653         u32 nr;
2654         u32 right_nritems;
2655         u32 data_end;
2656         u32 this_item_size;
2657
2658         if (empty)
2659                 nr = 0;
2660         else
2661                 nr = max_t(u32, 1, min_slot);
2662
2663         if (path->slots[0] >= left_nritems)
2664                 push_space += data_size;
2665
2666         slot = path->slots[1];
2667         i = left_nritems - 1;
2668         while (i >= nr) {
2669                 item = btrfs_item_nr(i);
2670
2671                 if (!empty && push_items > 0) {
2672                         if (path->slots[0] > i)
2673                                 break;
2674                         if (path->slots[0] == i) {
2675                                 int space = btrfs_leaf_free_space(left);
2676
2677                                 if (space + push_space * 2 > free_space)
2678                                         break;
2679                         }
2680                 }
2681
2682                 if (path->slots[0] == i)
2683                         push_space += data_size;
2684
2685                 this_item_size = btrfs_item_size(left, item);
2686                 if (this_item_size + sizeof(*item) + push_space > free_space)
2687                         break;
2688
2689                 push_items++;
2690                 push_space += this_item_size + sizeof(*item);
2691                 if (i == 0)
2692                         break;
2693                 i--;
2694         }
2695
2696         if (push_items == 0)
2697                 goto out_unlock;
2698
2699         WARN_ON(!empty && push_items == left_nritems);
2700
2701         /* push left to right */
2702         right_nritems = btrfs_header_nritems(right);
2703
2704         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
2705         push_space -= leaf_data_end(left);
2706
2707         /* make room in the right data area */
2708         data_end = leaf_data_end(right);
2709         memmove_extent_buffer(right,
2710                               BTRFS_LEAF_DATA_OFFSET + data_end - push_space,
2711                               BTRFS_LEAF_DATA_OFFSET + data_end,
2712                               BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
2713
2714         /* copy from the left data area */
2715         copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET +
2716                      BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
2717                      BTRFS_LEAF_DATA_OFFSET + leaf_data_end(left),
2718                      push_space);
2719
2720         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
2721                               btrfs_item_nr_offset(0),
2722                               right_nritems * sizeof(struct btrfs_item));
2723
2724         /* copy the items from left to right */
2725         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
2726                    btrfs_item_nr_offset(left_nritems - push_items),
2727                    push_items * sizeof(struct btrfs_item));
2728
2729         /* update the item pointers */
2730         btrfs_init_map_token(&token, right);
2731         right_nritems += push_items;
2732         btrfs_set_header_nritems(right, right_nritems);
2733         push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
2734         for (i = 0; i < right_nritems; i++) {
2735                 item = btrfs_item_nr(i);
2736                 push_space -= btrfs_token_item_size(&token, item);
2737                 btrfs_set_token_item_offset(&token, item, push_space);
2738         }
2739
2740         left_nritems -= push_items;
2741         btrfs_set_header_nritems(left, left_nritems);
2742
2743         if (left_nritems)
2744                 btrfs_mark_buffer_dirty(left);
2745         else
2746                 btrfs_clean_tree_block(left);
2747
2748         btrfs_mark_buffer_dirty(right);
2749
2750         btrfs_item_key(right, &disk_key, 0);
2751         btrfs_set_node_key(upper, &disk_key, slot + 1);
2752         btrfs_mark_buffer_dirty(upper);
2753
2754         /* then fixup the leaf pointer in the path */
2755         if (path->slots[0] >= left_nritems) {
2756                 path->slots[0] -= left_nritems;
2757                 if (btrfs_header_nritems(path->nodes[0]) == 0)
2758                         btrfs_clean_tree_block(path->nodes[0]);
2759                 btrfs_tree_unlock(path->nodes[0]);
2760                 free_extent_buffer(path->nodes[0]);
2761                 path->nodes[0] = right;
2762                 path->slots[1] += 1;
2763         } else {
2764                 btrfs_tree_unlock(right);
2765                 free_extent_buffer(right);
2766         }
2767         return 0;
2768
2769 out_unlock:
2770         btrfs_tree_unlock(right);
2771         free_extent_buffer(right);
2772         return 1;
2773 }
2774
2775 /*
2776  * push some data in the path leaf to the right, trying to free up at
2777  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
2778  *
2779  * returns 1 if the push failed because the other node didn't have enough
2780  * room, 0 if everything worked out and < 0 if there were major errors.
2781  *
2782  * this will push starting from min_slot to the end of the leaf.  It won't
2783  * push any slot lower than min_slot
2784  */
2785 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
2786                            *root, struct btrfs_path *path,
2787                            int min_data_size, int data_size,
2788                            int empty, u32 min_slot)
2789 {
2790         struct extent_buffer *left = path->nodes[0];
2791         struct extent_buffer *right;
2792         struct extent_buffer *upper;
2793         int slot;
2794         int free_space;
2795         u32 left_nritems;
2796         int ret;
2797
2798         if (!path->nodes[1])
2799                 return 1;
2800
2801         slot = path->slots[1];
2802         upper = path->nodes[1];
2803         if (slot >= btrfs_header_nritems(upper) - 1)
2804                 return 1;
2805
2806         btrfs_assert_tree_locked(path->nodes[1]);
2807
2808         right = btrfs_read_node_slot(upper, slot + 1);
2809         /*
2810          * slot + 1 is not valid or we fail to read the right node,
2811          * no big deal, just return.
2812          */
2813         if (IS_ERR(right))
2814                 return 1;
2815
2816         __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
2817
2818         free_space = btrfs_leaf_free_space(right);
2819         if (free_space < data_size)
2820                 goto out_unlock;
2821
2822         /* cow and double check */
2823         ret = btrfs_cow_block(trans, root, right, upper,
2824                               slot + 1, &right, BTRFS_NESTING_RIGHT_COW);
2825         if (ret)
2826                 goto out_unlock;
2827
2828         free_space = btrfs_leaf_free_space(right);
2829         if (free_space < data_size)
2830                 goto out_unlock;
2831
2832         left_nritems = btrfs_header_nritems(left);
2833         if (left_nritems == 0)
2834                 goto out_unlock;
2835
2836         if (check_sibling_keys(left, right)) {
2837                 ret = -EUCLEAN;
2838                 btrfs_tree_unlock(right);
2839                 free_extent_buffer(right);
2840                 return ret;
2841         }
2842         if (path->slots[0] == left_nritems && !empty) {
2843                 /* Key greater than all keys in the leaf, right neighbor has
2844                  * enough room for it and we're not emptying our leaf to delete
2845                  * it, therefore use right neighbor to insert the new item and
2846                  * no need to touch/dirty our left leaf. */
2847                 btrfs_tree_unlock(left);
2848                 free_extent_buffer(left);
2849                 path->nodes[0] = right;
2850                 path->slots[0] = 0;
2851                 path->slots[1]++;
2852                 return 0;
2853         }
2854
2855         return __push_leaf_right(path, min_data_size, empty,
2856                                 right, free_space, left_nritems, min_slot);
2857 out_unlock:
2858         btrfs_tree_unlock(right);
2859         free_extent_buffer(right);
2860         return 1;
2861 }
2862
2863 /*
2864  * push some data in the path leaf to the left, trying to free up at
2865  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
2866  *
2867  * max_slot can put a limit on how far into the leaf we'll push items.  The
2868  * item at 'max_slot' won't be touched.  Use (u32)-1 to make us do all the
2869  * items
2870  */
2871 static noinline int __push_leaf_left(struct btrfs_path *path, int data_size,
2872                                      int empty, struct extent_buffer *left,
2873                                      int free_space, u32 right_nritems,
2874                                      u32 max_slot)
2875 {
2876         struct btrfs_fs_info *fs_info = left->fs_info;
2877         struct btrfs_disk_key disk_key;
2878         struct extent_buffer *right = path->nodes[0];
2879         int i;
2880         int push_space = 0;
2881         int push_items = 0;
2882         struct btrfs_item *item;
2883         u32 old_left_nritems;
2884         u32 nr;
2885         int ret = 0;
2886         u32 this_item_size;
2887         u32 old_left_item_size;
2888         struct btrfs_map_token token;
2889
2890         if (empty)
2891                 nr = min(right_nritems, max_slot);
2892         else
2893                 nr = min(right_nritems - 1, max_slot);
2894
2895         for (i = 0; i < nr; i++) {
2896                 item = btrfs_item_nr(i);
2897
2898                 if (!empty && push_items > 0) {
2899                         if (path->slots[0] < i)
2900                                 break;
2901                         if (path->slots[0] == i) {
2902                                 int space = btrfs_leaf_free_space(right);
2903
2904                                 if (space + push_space * 2 > free_space)
2905                                         break;
2906                         }
2907                 }
2908
2909                 if (path->slots[0] == i)
2910                         push_space += data_size;
2911
2912                 this_item_size = btrfs_item_size(right, item);
2913                 if (this_item_size + sizeof(*item) + push_space > free_space)
2914                         break;
2915
2916                 push_items++;
2917                 push_space += this_item_size + sizeof(*item);
2918         }
2919
2920         if (push_items == 0) {
2921                 ret = 1;
2922                 goto out;
2923         }
2924         WARN_ON(!empty && push_items == btrfs_header_nritems(right));
2925
2926         /* push data from right to left */
2927         copy_extent_buffer(left, right,
2928                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
2929                            btrfs_item_nr_offset(0),
2930                            push_items * sizeof(struct btrfs_item));
2931
2932         push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
2933                      btrfs_item_offset_nr(right, push_items - 1);
2934
2935         copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET +
2936                      leaf_data_end(left) - push_space,
2937                      BTRFS_LEAF_DATA_OFFSET +
2938                      btrfs_item_offset_nr(right, push_items - 1),
2939                      push_space);
2940         old_left_nritems = btrfs_header_nritems(left);
2941         BUG_ON(old_left_nritems <= 0);
2942
2943         btrfs_init_map_token(&token, left);
2944         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
2945         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
2946                 u32 ioff;
2947
2948                 item = btrfs_item_nr(i);
2949
2950                 ioff = btrfs_token_item_offset(&token, item);
2951                 btrfs_set_token_item_offset(&token, item,
2952                       ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size));
2953         }
2954         btrfs_set_header_nritems(left, old_left_nritems + push_items);
2955
2956         /* fixup right node */
2957         if (push_items > right_nritems)
2958                 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
2959                        right_nritems);
2960
2961         if (push_items < right_nritems) {
2962                 push_space = btrfs_item_offset_nr(right, push_items - 1) -
2963                                                   leaf_data_end(right);
2964                 memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET +
2965                                       BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
2966                                       BTRFS_LEAF_DATA_OFFSET +
2967                                       leaf_data_end(right), push_space);
2968
2969                 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
2970                               btrfs_item_nr_offset(push_items),
2971                              (btrfs_header_nritems(right) - push_items) *
2972                              sizeof(struct btrfs_item));
2973         }
2974
2975         btrfs_init_map_token(&token, right);
2976         right_nritems -= push_items;
2977         btrfs_set_header_nritems(right, right_nritems);
2978         push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
2979         for (i = 0; i < right_nritems; i++) {
2980                 item = btrfs_item_nr(i);
2981
2982                 push_space = push_space - btrfs_token_item_size(&token, item);
2983                 btrfs_set_token_item_offset(&token, item, push_space);
2984         }
2985
2986         btrfs_mark_buffer_dirty(left);
2987         if (right_nritems)
2988                 btrfs_mark_buffer_dirty(right);
2989         else
2990                 btrfs_clean_tree_block(right);
2991
2992         btrfs_item_key(right, &disk_key, 0);
2993         fixup_low_keys(path, &disk_key, 1);
2994
2995         /* then fixup the leaf pointer in the path */
2996         if (path->slots[0] < push_items) {
2997                 path->slots[0] += old_left_nritems;
2998                 btrfs_tree_unlock(path->nodes[0]);
2999                 free_extent_buffer(path->nodes[0]);
3000                 path->nodes[0] = left;
3001                 path->slots[1] -= 1;
3002         } else {
3003                 btrfs_tree_unlock(left);
3004                 free_extent_buffer(left);
3005                 path->slots[0] -= push_items;
3006         }
3007         BUG_ON(path->slots[0] < 0);
3008         return ret;
3009 out:
3010         btrfs_tree_unlock(left);
3011         free_extent_buffer(left);
3012         return ret;
3013 }
3014
3015 /*
3016  * push some data in the path leaf to the left, trying to free up at
3017  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3018  *
3019  * max_slot can put a limit on how far into the leaf we'll push items.  The
3020  * item at 'max_slot' won't be touched.  Use (u32)-1 to make us push all the
3021  * items
3022  */
3023 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3024                           *root, struct btrfs_path *path, int min_data_size,
3025                           int data_size, int empty, u32 max_slot)
3026 {
3027         struct extent_buffer *right = path->nodes[0];
3028         struct extent_buffer *left;
3029         int slot;
3030         int free_space;
3031         u32 right_nritems;
3032         int ret = 0;
3033
3034         slot = path->slots[1];
3035         if (slot == 0)
3036                 return 1;
3037         if (!path->nodes[1])
3038                 return 1;
3039
3040         right_nritems = btrfs_header_nritems(right);
3041         if (right_nritems == 0)
3042                 return 1;
3043
3044         btrfs_assert_tree_locked(path->nodes[1]);
3045
3046         left = btrfs_read_node_slot(path->nodes[1], slot - 1);
3047         /*
3048          * slot - 1 is not valid or we fail to read the left node,
3049          * no big deal, just return.
3050          */
3051         if (IS_ERR(left))
3052                 return 1;
3053
3054         __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
3055
3056         free_space = btrfs_leaf_free_space(left);
3057         if (free_space < data_size) {
3058                 ret = 1;
3059                 goto out;
3060         }
3061
3062         /* cow and double check */
3063         ret = btrfs_cow_block(trans, root, left,
3064                               path->nodes[1], slot - 1, &left,
3065                               BTRFS_NESTING_LEFT_COW);
3066         if (ret) {
3067                 /* we hit -ENOSPC, but it isn't fatal here */
3068                 if (ret == -ENOSPC)
3069                         ret = 1;
3070                 goto out;
3071         }
3072
3073         free_space = btrfs_leaf_free_space(left);
3074         if (free_space < data_size) {
3075                 ret = 1;
3076                 goto out;
3077         }
3078
3079         if (check_sibling_keys(left, right)) {
3080                 ret = -EUCLEAN;
3081                 goto out;
3082         }
3083         return __push_leaf_left(path, min_data_size,
3084                                empty, left, free_space, right_nritems,
3085                                max_slot);
3086 out:
3087         btrfs_tree_unlock(left);
3088         free_extent_buffer(left);
3089         return ret;
3090 }
3091
3092 /*
3093  * split the path's leaf in two, making sure there is at least data_size
3094  * available for the resulting leaf level of the path.
3095  */
3096 static noinline void copy_for_split(struct btrfs_trans_handle *trans,
3097                                     struct btrfs_path *path,
3098                                     struct extent_buffer *l,
3099                                     struct extent_buffer *right,
3100                                     int slot, int mid, int nritems)
3101 {
3102         struct btrfs_fs_info *fs_info = trans->fs_info;
3103         int data_copy_size;
3104         int rt_data_off;
3105         int i;
3106         struct btrfs_disk_key disk_key;
3107         struct btrfs_map_token token;
3108
3109         nritems = nritems - mid;
3110         btrfs_set_header_nritems(right, nritems);
3111         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(l);
3112
3113         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
3114                            btrfs_item_nr_offset(mid),
3115                            nritems * sizeof(struct btrfs_item));
3116
3117         copy_extent_buffer(right, l,
3118                      BTRFS_LEAF_DATA_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) -
3119                      data_copy_size, BTRFS_LEAF_DATA_OFFSET +
3120                      leaf_data_end(l), data_copy_size);
3121
3122         rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_end_nr(l, mid);
3123
3124         btrfs_init_map_token(&token, right);
3125         for (i = 0; i < nritems; i++) {
3126                 struct btrfs_item *item = btrfs_item_nr(i);
3127                 u32 ioff;
3128
3129                 ioff = btrfs_token_item_offset(&token, item);
3130                 btrfs_set_token_item_offset(&token, item, ioff + rt_data_off);
3131         }
3132
3133         btrfs_set_header_nritems(l, mid);
3134         btrfs_item_key(right, &disk_key, 0);
3135         insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
3136
3137         btrfs_mark_buffer_dirty(right);
3138         btrfs_mark_buffer_dirty(l);
3139         BUG_ON(path->slots[0] != slot);
3140
3141         if (mid <= slot) {
3142                 btrfs_tree_unlock(path->nodes[0]);
3143                 free_extent_buffer(path->nodes[0]);
3144                 path->nodes[0] = right;
3145                 path->slots[0] -= mid;
3146                 path->slots[1] += 1;
3147         } else {
3148                 btrfs_tree_unlock(right);
3149                 free_extent_buffer(right);
3150         }
3151
3152         BUG_ON(path->slots[0] < 0);
3153 }
3154
3155 /*
3156  * double splits happen when we need to insert a big item in the middle
3157  * of a leaf.  A double split can leave us with 3 mostly empty leaves:
3158  * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
3159  *          A                 B                 C
3160  *
3161  * We avoid this by trying to push the items on either side of our target
3162  * into the adjacent leaves.  If all goes well we can avoid the double split
3163  * completely.
3164  */
3165 static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
3166                                           struct btrfs_root *root,
3167                                           struct btrfs_path *path,
3168                                           int data_size)
3169 {
3170         int ret;
3171         int progress = 0;
3172         int slot;
3173         u32 nritems;
3174         int space_needed = data_size;
3175
3176         slot = path->slots[0];
3177         if (slot < btrfs_header_nritems(path->nodes[0]))
3178                 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3179
3180         /*
3181          * try to push all the items after our slot into the
3182          * right leaf
3183          */
3184         ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
3185         if (ret < 0)
3186                 return ret;
3187
3188         if (ret == 0)
3189                 progress++;
3190
3191         nritems = btrfs_header_nritems(path->nodes[0]);
3192         /*
3193          * our goal is to get our slot at the start or end of a leaf.  If
3194          * we've done so we're done
3195          */
3196         if (path->slots[0] == 0 || path->slots[0] == nritems)
3197                 return 0;
3198
3199         if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3200                 return 0;
3201
3202         /* try to push all the items before our slot into the next leaf */
3203         slot = path->slots[0];
3204         space_needed = data_size;
3205         if (slot > 0)
3206                 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3207         ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
3208         if (ret < 0)
3209                 return ret;
3210
3211         if (ret == 0)
3212                 progress++;
3213
3214         if (progress)
3215                 return 0;
3216         return 1;
3217 }
3218
3219 /*
3220  * split the path's leaf in two, making sure there is at least data_size
3221  * available for the resulting leaf level of the path.
3222  *
3223  * returns 0 if all went well and < 0 on failure.
3224  */
3225 static noinline int split_leaf(struct btrfs_trans_handle *trans,
3226                                struct btrfs_root *root,
3227                                const struct btrfs_key *ins_key,
3228                                struct btrfs_path *path, int data_size,
3229                                int extend)
3230 {
3231         struct btrfs_disk_key disk_key;
3232         struct extent_buffer *l;
3233         u32 nritems;
3234         int mid;
3235         int slot;
3236         struct extent_buffer *right;
3237         struct btrfs_fs_info *fs_info = root->fs_info;
3238         int ret = 0;
3239         int wret;
3240         int split;
3241         int num_doubles = 0;
3242         int tried_avoid_double = 0;
3243
3244         l = path->nodes[0];
3245         slot = path->slots[0];
3246         if (extend && data_size + btrfs_item_size_nr(l, slot) +
3247             sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
3248                 return -EOVERFLOW;
3249
3250         /* first try to make some room by pushing left and right */
3251         if (data_size && path->nodes[1]) {
3252                 int space_needed = data_size;
3253
3254                 if (slot < btrfs_header_nritems(l))
3255                         space_needed -= btrfs_leaf_free_space(l);
3256
3257                 wret = push_leaf_right(trans, root, path, space_needed,
3258                                        space_needed, 0, 0);
3259                 if (wret < 0)
3260                         return wret;
3261                 if (wret) {
3262                         space_needed = data_size;
3263                         if (slot > 0)
3264                                 space_needed -= btrfs_leaf_free_space(l);
3265                         wret = push_leaf_left(trans, root, path, space_needed,
3266                                               space_needed, 0, (u32)-1);
3267                         if (wret < 0)
3268                                 return wret;
3269                 }
3270                 l = path->nodes[0];
3271
3272                 /* did the pushes work? */
3273                 if (btrfs_leaf_free_space(l) >= data_size)
3274                         return 0;
3275         }
3276
3277         if (!path->nodes[1]) {
3278                 ret = insert_new_root(trans, root, path, 1);
3279                 if (ret)
3280                         return ret;
3281         }
3282 again:
3283         split = 1;
3284         l = path->nodes[0];
3285         slot = path->slots[0];
3286         nritems = btrfs_header_nritems(l);
3287         mid = (nritems + 1) / 2;
3288
3289         if (mid <= slot) {
3290                 if (nritems == 1 ||
3291                     leaf_space_used(l, mid, nritems - mid) + data_size >
3292                         BTRFS_LEAF_DATA_SIZE(fs_info)) {
3293                         if (slot >= nritems) {
3294                                 split = 0;
3295                         } else {
3296                                 mid = slot;
3297                                 if (mid != nritems &&
3298                                     leaf_space_used(l, mid, nritems - mid) +
3299                                     data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3300                                         if (data_size && !tried_avoid_double)
3301                                                 goto push_for_double;
3302                                         split = 2;
3303                                 }
3304                         }
3305                 }
3306         } else {
3307                 if (leaf_space_used(l, 0, mid) + data_size >
3308                         BTRFS_LEAF_DATA_SIZE(fs_info)) {
3309                         if (!extend && data_size && slot == 0) {
3310                                 split = 0;
3311                         } else if ((extend || !data_size) && slot == 0) {
3312                                 mid = 1;
3313                         } else {
3314                                 mid = slot;
3315                                 if (mid != nritems &&
3316                                     leaf_space_used(l, mid, nritems - mid) +
3317                                     data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3318                                         if (data_size && !tried_avoid_double)
3319                                                 goto push_for_double;
3320                                         split = 2;
3321                                 }
3322                         }
3323                 }
3324         }
3325
3326         if (split == 0)
3327                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
3328         else
3329                 btrfs_item_key(l, &disk_key, mid);
3330
3331         /*
3332          * We have to about BTRFS_NESTING_NEW_ROOT here if we've done a double
3333          * split, because we're only allowed to have MAX_LOCKDEP_SUBCLASSES
3334          * subclasses, which is 8 at the time of this patch, and we've maxed it
3335          * out.  In the future we could add a
3336          * BTRFS_NESTING_SPLIT_THE_SPLITTENING if we need to, but for now just
3337          * use BTRFS_NESTING_NEW_ROOT.
3338          */
3339         right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
3340                                        &disk_key, 0, l->start, 0,
3341                                        num_doubles ? BTRFS_NESTING_NEW_ROOT :
3342                                        BTRFS_NESTING_SPLIT);
3343         if (IS_ERR(right))
3344                 return PTR_ERR(right);
3345
3346         root_add_used(root, fs_info->nodesize);
3347
3348         if (split == 0) {
3349                 if (mid <= slot) {
3350                         btrfs_set_header_nritems(right, 0);
3351                         insert_ptr(trans, path, &disk_key,
3352                                    right->start, path->slots[1] + 1, 1);
3353                         btrfs_tree_unlock(path->nodes[0]);
3354                         free_extent_buffer(path->nodes[0]);
3355                         path->nodes[0] = right;
3356                         path->slots[0] = 0;
3357                         path->slots[1] += 1;
3358                 } else {
3359                         btrfs_set_header_nritems(right, 0);
3360                         insert_ptr(trans, path, &disk_key,
3361                                    right->start, path->slots[1], 1);
3362                         btrfs_tree_unlock(path->nodes[0]);
3363                         free_extent_buffer(path->nodes[0]);
3364                         path->nodes[0] = right;
3365                         path->slots[0] = 0;
3366                         if (path->slots[1] == 0)
3367                                 fixup_low_keys(path, &disk_key, 1);
3368                 }
3369                 /*
3370                  * We create a new leaf 'right' for the required ins_len and
3371                  * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
3372                  * the content of ins_len to 'right'.
3373                  */
3374                 return ret;
3375         }
3376
3377         copy_for_split(trans, path, l, right, slot, mid, nritems);
3378
3379         if (split == 2) {
3380                 BUG_ON(num_doubles != 0);
3381                 num_doubles++;
3382                 goto again;
3383         }
3384
3385         return 0;
3386
3387 push_for_double:
3388         push_for_double_split(trans, root, path, data_size);
3389         tried_avoid_double = 1;
3390         if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3391                 return 0;
3392         goto again;
3393 }
3394
3395 static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3396                                          struct btrfs_root *root,
3397                                          struct btrfs_path *path, int ins_len)
3398 {
3399         struct btrfs_key key;
3400         struct extent_buffer *leaf;
3401         struct btrfs_file_extent_item *fi;
3402         u64 extent_len = 0;
3403         u32 item_size;
3404         int ret;
3405
3406         leaf = path->nodes[0];
3407         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3408
3409         BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3410                key.type != BTRFS_EXTENT_CSUM_KEY);
3411
3412         if (btrfs_leaf_free_space(leaf) >= ins_len)
3413                 return 0;
3414
3415         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3416         if (key.type == BTRFS_EXTENT_DATA_KEY) {
3417                 fi = btrfs_item_ptr(leaf, path->slots[0],
3418                                     struct btrfs_file_extent_item);
3419                 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3420         }
3421         btrfs_release_path(path);
3422
3423         path->keep_locks = 1;
3424         path->search_for_split = 1;
3425         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3426         path->search_for_split = 0;
3427         if (ret > 0)
3428                 ret = -EAGAIN;
3429         if (ret < 0)
3430                 goto err;
3431
3432         ret = -EAGAIN;
3433         leaf = path->nodes[0];
3434         /* if our item isn't there, return now */
3435         if (item_size != btrfs_item_size_nr(leaf, path->slots[0]))
3436                 goto err;
3437
3438         /* the leaf has  changed, it now has room.  return now */
3439         if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
3440                 goto err;
3441
3442         if (key.type == BTRFS_EXTENT_DATA_KEY) {
3443                 fi = btrfs_item_ptr(leaf, path->slots[0],
3444                                     struct btrfs_file_extent_item);
3445                 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3446                         goto err;
3447         }
3448
3449         ret = split_leaf(trans, root, &key, path, ins_len, 1);
3450         if (ret)
3451                 goto err;
3452
3453         path->keep_locks = 0;
3454         btrfs_unlock_up_safe(path, 1);
3455         return 0;
3456 err:
3457         path->keep_locks = 0;
3458         return ret;
3459 }
3460
3461 static noinline int split_item(struct btrfs_path *path,
3462                                const struct btrfs_key *new_key,
3463                                unsigned long split_offset)
3464 {
3465         struct extent_buffer *leaf;
3466         struct btrfs_item *item;
3467         struct btrfs_item *new_item;
3468         int slot;
3469         char *buf;
3470         u32 nritems;
3471         u32 item_size;
3472         u32 orig_offset;
3473         struct btrfs_disk_key disk_key;
3474
3475         leaf = path->nodes[0];
3476         BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));
3477
3478         item = btrfs_item_nr(path->slots[0]);
3479         orig_offset = btrfs_item_offset(leaf, item);
3480         item_size = btrfs_item_size(leaf, item);
3481
3482         buf = kmalloc(item_size, GFP_NOFS);
3483         if (!buf)
3484                 return -ENOMEM;
3485
3486         read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3487                             path->slots[0]), item_size);
3488
3489         slot = path->slots[0] + 1;
3490         nritems = btrfs_header_nritems(leaf);
3491         if (slot != nritems) {
3492                 /* shift the items */
3493                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
3494                                 btrfs_item_nr_offset(slot),
3495                                 (nritems - slot) * sizeof(struct btrfs_item));
3496         }
3497
3498         btrfs_cpu_key_to_disk(&disk_key, new_key);
3499         btrfs_set_item_key(leaf, &disk_key, slot);
3500
3501         new_item = btrfs_item_nr(slot);
3502
3503         btrfs_set_item_offset(leaf, new_item, orig_offset);
3504         btrfs_set_item_size(leaf, new_item, item_size - split_offset);
3505
3506         btrfs_set_item_offset(leaf, item,
3507                               orig_offset + item_size - split_offset);
3508         btrfs_set_item_size(leaf, item, split_offset);
3509
3510         btrfs_set_header_nritems(leaf, nritems + 1);
3511
3512         /* write the data for the start of the original item */
3513         write_extent_buffer(leaf, buf,
3514                             btrfs_item_ptr_offset(leaf, path->slots[0]),
3515                             split_offset);
3516
3517         /* write the data for the new item */
3518         write_extent_buffer(leaf, buf + split_offset,
3519                             btrfs_item_ptr_offset(leaf, slot),
3520                             item_size - split_offset);
3521         btrfs_mark_buffer_dirty(leaf);
3522
3523         BUG_ON(btrfs_leaf_free_space(leaf) < 0);
3524         kfree(buf);
3525         return 0;
3526 }
3527
3528 /*
3529  * This function splits a single item into two items,
3530  * giving 'new_key' to the new item and splitting the
3531  * old one at split_offset (from the start of the item).
3532  *
3533  * The path may be released by this operation.  After
3534  * the split, the path is pointing to the old item.  The
3535  * new item is going to be in the same node as the old one.
3536  *
3537  * Note, the item being split must be smaller enough to live alone on
3538  * a tree block with room for one extra struct btrfs_item
3539  *
3540  * This allows us to split the item in place, keeping a lock on the
3541  * leaf the entire time.
3542  */
3543 int btrfs_split_item(struct btrfs_trans_handle *trans,
3544                      struct btrfs_root *root,
3545                      struct btrfs_path *path,
3546                      const struct btrfs_key *new_key,
3547                      unsigned long split_offset)
3548 {
3549         int ret;
3550         ret = setup_leaf_for_split(trans, root, path,
3551                                    sizeof(struct btrfs_item));
3552         if (ret)
3553                 return ret;
3554
3555         ret = split_item(path, new_key, split_offset);
3556         return ret;
3557 }
3558
3559 /*
3560  * This function duplicate a item, giving 'new_key' to the new item.
3561  * It guarantees both items live in the same tree leaf and the new item
3562  * is contiguous with the original item.
3563  *
3564  * This allows us to split file extent in place, keeping a lock on the
3565  * leaf the entire time.
3566  */
3567 int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
3568                          struct btrfs_root *root,
3569                          struct btrfs_path *path,
3570                          const struct btrfs_key *new_key)
3571 {
3572         struct extent_buffer *leaf;
3573         int ret;
3574         u32 item_size;
3575
3576         leaf = path->nodes[0];
3577         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3578         ret = setup_leaf_for_split(trans, root, path,
3579                                    item_size + sizeof(struct btrfs_item));
3580         if (ret)
3581                 return ret;
3582
3583         path->slots[0]++;
3584         setup_items_for_insert(root, path, new_key, &item_size, 1);
3585         leaf = path->nodes[0];
3586         memcpy_extent_buffer(leaf,
3587                              btrfs_item_ptr_offset(leaf, path->slots[0]),
3588                              btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
3589                              item_size);
3590         return 0;
3591 }
3592
3593 /*
3594  * make the item pointed to by the path smaller.  new_size indicates
3595  * how small to make it, and from_end tells us if we just chop bytes
3596  * off the end of the item or if we shift the item to chop bytes off
3597  * the front.
3598  */
3599 void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end)
3600 {
3601         int slot;
3602         struct extent_buffer *leaf;
3603         struct btrfs_item *item;
3604         u32 nritems;
3605         unsigned int data_end;
3606         unsigned int old_data_start;
3607         unsigned int old_size;
3608         unsigned int size_diff;
3609         int i;
3610         struct btrfs_map_token token;
3611
3612         leaf = path->nodes[0];
3613         slot = path->slots[0];
3614
3615         old_size = btrfs_item_size_nr(leaf, slot);
3616         if (old_size == new_size)
3617                 return;
3618
3619         nritems = btrfs_header_nritems(leaf);
3620         data_end = leaf_data_end(leaf);
3621
3622         old_data_start = btrfs_item_offset_nr(leaf, slot);
3623
3624         size_diff = old_size - new_size;
3625
3626         BUG_ON(slot < 0);
3627         BUG_ON(slot >= nritems);
3628
3629         /*
3630          * item0..itemN ... dataN.offset..dataN.size .. data0.size
3631          */
3632         /* first correct the data pointers */
3633         btrfs_init_map_token(&token, leaf);
3634         for (i = slot; i < nritems; i++) {
3635                 u32 ioff;
3636                 item = btrfs_item_nr(i);
3637
3638                 ioff = btrfs_token_item_offset(&token, item);
3639                 btrfs_set_token_item_offset(&token, item, ioff + size_diff);
3640         }
3641
3642         /* shift the data */
3643         if (from_end) {
3644                 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3645                               data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
3646                               data_end, old_data_start + new_size - data_end);
3647         } else {
3648                 struct btrfs_disk_key disk_key;
3649                 u64 offset;
3650
3651                 btrfs_item_key(leaf, &disk_key, slot);
3652
3653                 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
3654                         unsigned long ptr;
3655                         struct btrfs_file_extent_item *fi;
3656
3657                         fi = btrfs_item_ptr(leaf, slot,
3658                                             struct btrfs_file_extent_item);
3659                         fi = (struct btrfs_file_extent_item *)(
3660                              (unsigned long)fi - size_diff);
3661
3662                         if (btrfs_file_extent_type(leaf, fi) ==
3663                             BTRFS_FILE_EXTENT_INLINE) {
3664                                 ptr = btrfs_item_ptr_offset(leaf, slot);
3665                                 memmove_extent_buffer(leaf, ptr,
3666                                       (unsigned long)fi,
3667                                       BTRFS_FILE_EXTENT_INLINE_DATA_START);
3668                         }
3669                 }
3670
3671                 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3672                               data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
3673                               data_end, old_data_start - data_end);
3674
3675                 offset = btrfs_disk_key_offset(&disk_key);
3676                 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
3677                 btrfs_set_item_key(leaf, &disk_key, slot);
3678                 if (slot == 0)
3679                         fixup_low_keys(path, &disk_key, 1);
3680         }
3681
3682         item = btrfs_item_nr(slot);
3683         btrfs_set_item_size(leaf, item, new_size);
3684         btrfs_mark_buffer_dirty(leaf);
3685
3686         if (btrfs_leaf_free_space(leaf) < 0) {
3687                 btrfs_print_leaf(leaf);
3688                 BUG();
3689         }
3690 }
3691
3692 /*
3693  * make the item pointed to by the path bigger, data_size is the added size.
3694  */
3695 void btrfs_extend_item(struct btrfs_path *path, u32 data_size)
3696 {
3697         int slot;
3698         struct extent_buffer *leaf;
3699         struct btrfs_item *item;
3700         u32 nritems;
3701         unsigned int data_end;
3702         unsigned int old_data;
3703         unsigned int old_size;
3704         int i;
3705         struct btrfs_map_token token;
3706
3707         leaf = path->nodes[0];
3708
3709         nritems = btrfs_header_nritems(leaf);
3710         data_end = leaf_data_end(leaf);
3711
3712         if (btrfs_leaf_free_space(leaf) < data_size) {
3713                 btrfs_print_leaf(leaf);
3714                 BUG();
3715         }
3716         slot = path->slots[0];
3717         old_data = btrfs_item_end_nr(leaf, slot);
3718
3719         BUG_ON(slot < 0);
3720         if (slot >= nritems) {
3721                 btrfs_print_leaf(leaf);
3722                 btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
3723                            slot, nritems);
3724                 BUG();
3725         }
3726
3727         /*
3728          * item0..itemN ... dataN.offset..dataN.size .. data0.size
3729          */
3730         /* first correct the data pointers */
3731         btrfs_init_map_token(&token, leaf);
3732         for (i = slot; i < nritems; i++) {
3733                 u32 ioff;
3734                 item = btrfs_item_nr(i);
3735
3736                 ioff = btrfs_token_item_offset(&token, item);
3737                 btrfs_set_token_item_offset(&token, item, ioff - data_size);
3738         }
3739
3740         /* shift the data */
3741         memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3742                       data_end - data_size, BTRFS_LEAF_DATA_OFFSET +
3743                       data_end, old_data - data_end);
3744
3745         data_end = old_data;
3746         old_size = btrfs_item_size_nr(leaf, slot);
3747         item = btrfs_item_nr(slot);
3748         btrfs_set_item_size(leaf, item, old_size + data_size);
3749         btrfs_mark_buffer_dirty(leaf);
3750
3751         if (btrfs_leaf_free_space(leaf) < 0) {
3752                 btrfs_print_leaf(leaf);
3753                 BUG();
3754         }
3755 }
3756
3757 /**
3758  * setup_items_for_insert - Helper called before inserting one or more items
3759  * to a leaf. Main purpose is to save stack depth by doing the bulk of the work
3760  * in a function that doesn't call btrfs_search_slot
3761  *
3762  * @root:       root we are inserting items to
3763  * @path:       points to the leaf/slot where we are going to insert new items
3764  * @cpu_key:    array of keys for items to be inserted
3765  * @data_size:  size of the body of each item we are going to insert
3766  * @nr:         size of @cpu_key/@data_size arrays
3767  */
3768 void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
3769                             const struct btrfs_key *cpu_key, u32 *data_size,
3770                             int nr)
3771 {
3772         struct btrfs_fs_info *fs_info = root->fs_info;
3773         struct btrfs_item *item;
3774         int i;
3775         u32 nritems;
3776         unsigned int data_end;
3777         struct btrfs_disk_key disk_key;
3778         struct extent_buffer *leaf;
3779         int slot;
3780         struct btrfs_map_token token;
3781         u32 total_size;
3782         u32 total_data = 0;
3783
3784         for (i = 0; i < nr; i++)
3785                 total_data += data_size[i];
3786         total_size = total_data + (nr * sizeof(struct btrfs_item));
3787
3788         if (path->slots[0] == 0) {
3789                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
3790                 fixup_low_keys(path, &disk_key, 1);
3791         }
3792         btrfs_unlock_up_safe(path, 1);
3793
3794         leaf = path->nodes[0];
3795         slot = path->slots[0];
3796
3797         nritems = btrfs_header_nritems(leaf);
3798         data_end = leaf_data_end(leaf);
3799
3800         if (btrfs_leaf_free_space(leaf) < total_size) {
3801                 btrfs_print_leaf(leaf);
3802                 btrfs_crit(fs_info, "not enough freespace need %u have %d",
3803                            total_size, btrfs_leaf_free_space(leaf));
3804                 BUG();
3805         }
3806
3807         btrfs_init_map_token(&token, leaf);
3808         if (slot != nritems) {
3809                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
3810
3811                 if (old_data < data_end) {
3812                         btrfs_print_leaf(leaf);
3813                         btrfs_crit(fs_info,
3814                 "item at slot %d with data offset %u beyond data end of leaf %u",
3815                                    slot, old_data, data_end);
3816                         BUG();
3817                 }
3818                 /*
3819                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
3820                  */
3821                 /* first correct the data pointers */
3822                 for (i = slot; i < nritems; i++) {
3823                         u32 ioff;
3824
3825                         item = btrfs_item_nr(i);
3826                         ioff = btrfs_token_item_offset(&token, item);
3827                         btrfs_set_token_item_offset(&token, item,
3828                                                     ioff - total_data);
3829                 }
3830                 /* shift the items */
3831                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
3832                               btrfs_item_nr_offset(slot),
3833                               (nritems - slot) * sizeof(struct btrfs_item));
3834
3835                 /* shift the data */
3836                 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3837                               data_end - total_data, BTRFS_LEAF_DATA_OFFSET +
3838                               data_end, old_data - data_end);
3839                 data_end = old_data;
3840         }
3841
3842         /* setup the item for the new data */
3843         for (i = 0; i < nr; i++) {
3844                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
3845                 btrfs_set_item_key(leaf, &disk_key, slot + i);
3846                 item = btrfs_item_nr(slot + i);
3847                 data_end -= data_size[i];
3848                 btrfs_set_token_item_offset(&token, item, data_end);
3849                 btrfs_set_token_item_size(&token, item, data_size[i]);
3850         }
3851
3852         btrfs_set_header_nritems(leaf, nritems + nr);
3853         btrfs_mark_buffer_dirty(leaf);
3854
3855         if (btrfs_leaf_free_space(leaf) < 0) {
3856                 btrfs_print_leaf(leaf);
3857                 BUG();
3858         }
3859 }
3860
3861 /*
3862  * Given a key and some data, insert items into the tree.
3863  * This does all the path init required, making room in the tree if needed.
3864  */
3865 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
3866                             struct btrfs_root *root,
3867                             struct btrfs_path *path,
3868                             const struct btrfs_key *cpu_key, u32 *data_size,
3869                             int nr)
3870 {
3871         int ret = 0;
3872         int slot;
3873         int i;
3874         u32 total_size = 0;
3875         u32 total_data = 0;
3876
3877         for (i = 0; i < nr; i++)
3878                 total_data += data_size[i];
3879
3880         total_size = total_data + (nr * sizeof(struct btrfs_item));
3881         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
3882         if (ret == 0)
3883                 return -EEXIST;
3884         if (ret < 0)
3885                 return ret;
3886
3887         slot = path->slots[0];
3888         BUG_ON(slot < 0);
3889
3890         setup_items_for_insert(root, path, cpu_key, data_size, nr);
3891         return 0;
3892 }
3893
3894 /*
3895  * Given a key and some data, insert an item into the tree.
3896  * This does all the path init required, making room in the tree if needed.
3897  */
3898 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3899                       const struct btrfs_key *cpu_key, void *data,
3900                       u32 data_size)
3901 {
3902         int ret = 0;
3903         struct btrfs_path *path;
3904         struct extent_buffer *leaf;
3905         unsigned long ptr;
3906
3907         path = btrfs_alloc_path();
3908         if (!path)
3909                 return -ENOMEM;
3910         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
3911         if (!ret) {
3912                 leaf = path->nodes[0];
3913                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
3914                 write_extent_buffer(leaf, data, ptr, data_size);
3915                 btrfs_mark_buffer_dirty(leaf);
3916         }
3917         btrfs_free_path(path);
3918         return ret;
3919 }
3920
3921 /*
3922  * delete the pointer from a given node.
3923  *
3924  * the tree should have been previously balanced so the deletion does not
3925  * empty a node.
3926  */
3927 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
3928                     int level, int slot)
3929 {
3930         struct extent_buffer *parent = path->nodes[level];
3931         u32 nritems;
3932         int ret;
3933
3934         nritems = btrfs_header_nritems(parent);
3935         if (slot != nritems - 1) {
3936                 if (level) {
3937                         ret = btrfs_tree_mod_log_insert_move(parent, slot,
3938                                         slot + 1, nritems - slot - 1);
3939                         BUG_ON(ret < 0);
3940                 }
3941                 memmove_extent_buffer(parent,
3942                               btrfs_node_key_ptr_offset(slot),
3943                               btrfs_node_key_ptr_offset(slot + 1),
3944                               sizeof(struct btrfs_key_ptr) *
3945                               (nritems - slot - 1));
3946         } else if (level) {
3947                 ret = btrfs_tree_mod_log_insert_key(parent, slot,
3948                                 BTRFS_MOD_LOG_KEY_REMOVE, GFP_NOFS);
3949                 BUG_ON(ret < 0);
3950         }
3951
3952         nritems--;
3953         btrfs_set_header_nritems(parent, nritems);
3954         if (nritems == 0 && parent == root->node) {
3955                 BUG_ON(btrfs_header_level(root->node) != 1);
3956                 /* just turn the root into a leaf and break */
3957                 btrfs_set_header_level(root->node, 0);
3958         } else if (slot == 0) {
3959                 struct btrfs_disk_key disk_key;
3960
3961                 btrfs_node_key(parent, &disk_key, 0);
3962                 fixup_low_keys(path, &disk_key, level + 1);
3963         }
3964         btrfs_mark_buffer_dirty(parent);
3965 }
3966
3967 /*
3968  * a helper function to delete the leaf pointed to by path->slots[1] and
3969  * path->nodes[1].
3970  *
3971  * This deletes the pointer in path->nodes[1] and frees the leaf
3972  * block extent.  zero is returned if it all worked out, < 0 otherwise.
3973  *
3974  * The path must have already been setup for deleting the leaf, including
3975  * all the proper balancing.  path->nodes[1] must be locked.
3976  */
3977 static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
3978                                     struct btrfs_root *root,
3979                                     struct btrfs_path *path,
3980                                     struct extent_buffer *leaf)
3981 {
3982         WARN_ON(btrfs_header_generation(leaf) != trans->transid);
3983         del_ptr(root, path, 1, path->slots[1]);
3984
3985         /*
3986          * btrfs_free_extent is expensive, we want to make sure we
3987          * aren't holding any locks when we call it
3988          */
3989         btrfs_unlock_up_safe(path, 0);
3990
3991         root_sub_used(root, leaf->len);
3992
3993         atomic_inc(&leaf->refs);
3994         btrfs_free_tree_block(trans, root, leaf, 0, 1);
3995         free_extent_buffer_stale(leaf);
3996 }
3997 /*
3998  * delete the item at the leaf level in path.  If that empties
3999  * the leaf, remove it from the tree
4000  */
4001 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4002                     struct btrfs_path *path, int slot, int nr)
4003 {
4004         struct btrfs_fs_info *fs_info = root->fs_info;
4005         struct extent_buffer *leaf;
4006         struct btrfs_item *item;
4007         u32 last_off;
4008         u32 dsize = 0;
4009         int ret = 0;
4010         int wret;
4011         int i;
4012         u32 nritems;
4013
4014         leaf = path->nodes[0];
4015         last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4016
4017         for (i = 0; i < nr; i++)
4018                 dsize += btrfs_item_size_nr(leaf, slot + i);
4019
4020         nritems = btrfs_header_nritems(leaf);
4021
4022         if (slot + nr != nritems) {
4023                 int data_end = leaf_data_end(leaf);
4024                 struct btrfs_map_token token;
4025
4026                 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4027                               data_end + dsize,
4028                               BTRFS_LEAF_DATA_OFFSET + data_end,
4029                               last_off - data_end);
4030
4031                 btrfs_init_map_token(&token, leaf);
4032                 for (i = slot + nr; i < nritems; i++) {
4033                         u32 ioff;
4034
4035                         item = btrfs_item_nr(i);
4036                         ioff = btrfs_token_item_offset(&token, item);
4037                         btrfs_set_token_item_offset(&token, item, ioff + dsize);
4038                 }
4039
4040                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
4041                               btrfs_item_nr_offset(slot + nr),
4042                               sizeof(struct btrfs_item) *
4043                               (nritems - slot - nr));
4044         }
4045         btrfs_set_header_nritems(leaf, nritems - nr);
4046         nritems -= nr;
4047
4048         /* delete the leaf if we've emptied it */
4049         if (nritems == 0) {
4050                 if (leaf == root->node) {
4051                         btrfs_set_header_level(leaf, 0);
4052                 } else {
4053                         btrfs_clean_tree_block(leaf);
4054                         btrfs_del_leaf(trans, root, path, leaf);
4055                 }
4056         } else {
4057                 int used = leaf_space_used(leaf, 0, nritems);
4058                 if (slot == 0) {
4059                         struct btrfs_disk_key disk_key;
4060
4061                         btrfs_item_key(leaf, &disk_key, 0);
4062                         fixup_low_keys(path, &disk_key, 1);
4063                 }
4064
4065                 /* delete the leaf if it is mostly empty */
4066                 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
4067                         /* push_leaf_left fixes the path.
4068                          * make sure the path still points to our leaf
4069                          * for possible call to del_ptr below
4070                          */
4071                         slot = path->slots[1];
4072                         atomic_inc(&leaf->refs);
4073
4074                         wret = push_leaf_left(trans, root, path, 1, 1,
4075                                               1, (u32)-1);
4076                         if (wret < 0 && wret != -ENOSPC)
4077                                 ret = wret;
4078
4079                         if (path->nodes[0] == leaf &&
4080                             btrfs_header_nritems(leaf)) {
4081                                 wret = push_leaf_right(trans, root, path, 1,
4082                                                        1, 1, 0);
4083                                 if (wret < 0 && wret != -ENOSPC)
4084                                         ret = wret;
4085                         }
4086
4087                         if (btrfs_header_nritems(leaf) == 0) {
4088                                 path->slots[1] = slot;
4089                                 btrfs_del_leaf(trans, root, path, leaf);
4090                                 free_extent_buffer(leaf);
4091                                 ret = 0;
4092                         } else {
4093                                 /* if we're still in the path, make sure
4094                                  * we're dirty.  Otherwise, one of the
4095                                  * push_leaf functions must have already
4096                                  * dirtied this buffer
4097                                  */
4098                                 if (path->nodes[0] == leaf)
4099                                         btrfs_mark_buffer_dirty(leaf);
4100                                 free_extent_buffer(leaf);
4101                         }
4102                 } else {
4103                         btrfs_mark_buffer_dirty(leaf);
4104                 }
4105         }
4106         return ret;
4107 }
4108
4109 /*
4110  * search the tree again to find a leaf with lesser keys
4111  * returns 0 if it found something or 1 if there are no lesser leaves.
4112  * returns < 0 on io errors.
4113  *
4114  * This may release the path, and so you may lose any locks held at the
4115  * time you call it.
4116  */
4117 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
4118 {
4119         struct btrfs_key key;
4120         struct btrfs_disk_key found_key;
4121         int ret;
4122
4123         btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
4124
4125         if (key.offset > 0) {
4126                 key.offset--;
4127         } else if (key.type > 0) {
4128                 key.type--;
4129                 key.offset = (u64)-1;
4130         } else if (key.objectid > 0) {
4131                 key.objectid--;
4132                 key.type = (u8)-1;
4133                 key.offset = (u64)-1;
4134         } else {
4135                 return 1;
4136         }
4137
4138         btrfs_release_path(path);
4139         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4140         if (ret < 0)
4141                 return ret;
4142         btrfs_item_key(path->nodes[0], &found_key, 0);
4143         ret = comp_keys(&found_key, &key);
4144         /*
4145          * We might have had an item with the previous key in the tree right
4146          * before we released our path. And after we released our path, that
4147          * item might have been pushed to the first slot (0) of the leaf we
4148          * were holding due to a tree balance. Alternatively, an item with the
4149          * previous key can exist as the only element of a leaf (big fat item).
4150          * Therefore account for these 2 cases, so that our callers (like
4151          * btrfs_previous_item) don't miss an existing item with a key matching
4152          * the previous key we computed above.
4153          */
4154         if (ret <= 0)
4155                 return 0;
4156         return 1;
4157 }
4158
4159 /*
4160  * A helper function to walk down the tree starting at min_key, and looking
4161  * for nodes or leaves that are have a minimum transaction id.
4162  * This is used by the btree defrag code, and tree logging
4163  *
4164  * This does not cow, but it does stuff the starting key it finds back
4165  * into min_key, so you can call btrfs_search_slot with cow=1 on the
4166  * key and get a writable path.
4167  *
4168  * This honors path->lowest_level to prevent descent past a given level
4169  * of the tree.
4170  *
4171  * min_trans indicates the oldest transaction that you are interested
4172  * in walking through.  Any nodes or leaves older than min_trans are
4173  * skipped over (without reading them).
4174  *
4175  * returns zero if something useful was found, < 0 on error and 1 if there
4176  * was nothing in the tree that matched the search criteria.
4177  */
4178 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4179                          struct btrfs_path *path,
4180                          u64 min_trans)
4181 {
4182         struct extent_buffer *cur;
4183         struct btrfs_key found_key;
4184         int slot;
4185         int sret;
4186         u32 nritems;
4187         int level;
4188         int ret = 1;
4189         int keep_locks = path->keep_locks;
4190
4191         path->keep_locks = 1;
4192 again:
4193         cur = btrfs_read_lock_root_node(root);
4194         level = btrfs_header_level(cur);
4195         WARN_ON(path->nodes[level]);
4196         path->nodes[level] = cur;
4197         path->locks[level] = BTRFS_READ_LOCK;
4198
4199         if (btrfs_header_generation(cur) < min_trans) {
4200                 ret = 1;
4201                 goto out;
4202         }
4203         while (1) {
4204                 nritems = btrfs_header_nritems(cur);
4205                 level = btrfs_header_level(cur);
4206                 sret = btrfs_bin_search(cur, min_key, &slot);
4207                 if (sret < 0) {
4208                         ret = sret;
4209                         goto out;
4210                 }
4211
4212                 /* at the lowest level, we're done, setup the path and exit */
4213                 if (level == path->lowest_level) {
4214                         if (slot >= nritems)
4215                                 goto find_next_key;
4216                         ret = 0;
4217                         path->slots[level] = slot;
4218                         btrfs_item_key_to_cpu(cur, &found_key, slot);
4219                         goto out;
4220                 }
4221                 if (sret && slot > 0)
4222                         slot--;
4223                 /*
4224                  * check this node pointer against the min_trans parameters.
4225                  * If it is too old, skip to the next one.
4226                  */
4227                 while (slot < nritems) {
4228                         u64 gen;
4229
4230                         gen = btrfs_node_ptr_generation(cur, slot);
4231                         if (gen < min_trans) {
4232                                 slot++;
4233                                 continue;
4234                         }
4235                         break;
4236                 }
4237 find_next_key:
4238                 /*
4239                  * we didn't find a candidate key in this node, walk forward
4240                  * and find another one
4241                  */
4242                 if (slot >= nritems) {
4243                         path->slots[level] = slot;
4244                         sret = btrfs_find_next_key(root, path, min_key, level,
4245                                                   min_trans);
4246                         if (sret == 0) {
4247                                 btrfs_release_path(path);
4248                                 goto again;
4249                         } else {
4250                                 goto out;
4251                         }
4252                 }
4253                 /* save our key for returning back */
4254                 btrfs_node_key_to_cpu(cur, &found_key, slot);
4255                 path->slots[level] = slot;
4256                 if (level == path->lowest_level) {
4257                         ret = 0;
4258                         goto out;
4259                 }
4260                 cur = btrfs_read_node_slot(cur, slot);
4261                 if (IS_ERR(cur)) {
4262                         ret = PTR_ERR(cur);
4263                         goto out;
4264                 }
4265
4266                 btrfs_tree_read_lock(cur);
4267
4268                 path->locks[level - 1] = BTRFS_READ_LOCK;
4269                 path->nodes[level - 1] = cur;
4270                 unlock_up(path, level, 1, 0, NULL);
4271         }
4272 out:
4273         path->keep_locks = keep_locks;
4274         if (ret == 0) {
4275                 btrfs_unlock_up_safe(path, path->lowest_level + 1);
4276                 memcpy(min_key, &found_key, sizeof(found_key));
4277         }
4278         return ret;
4279 }
4280
4281 /*
4282  * this is similar to btrfs_next_leaf, but does not try to preserve
4283  * and fixup the path.  It looks for and returns the next key in the
4284  * tree based on the current path and the min_trans parameters.
4285  *
4286  * 0 is returned if another key is found, < 0 if there are any errors
4287  * and 1 is returned if there are no higher keys in the tree
4288  *
4289  * path->keep_locks should be set to 1 on the search made before
4290  * calling this function.
4291  */
4292 int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4293                         struct btrfs_key *key, int level, u64 min_trans)
4294 {
4295         int slot;
4296         struct extent_buffer *c;
4297
4298         WARN_ON(!path->keep_locks && !path->skip_locking);
4299         while (level < BTRFS_MAX_LEVEL) {
4300                 if (!path->nodes[level])
4301                         return 1;
4302
4303                 slot = path->slots[level] + 1;
4304                 c = path->nodes[level];
4305 next:
4306                 if (slot >= btrfs_header_nritems(c)) {
4307                         int ret;
4308                         int orig_lowest;
4309                         struct btrfs_key cur_key;
4310                         if (level + 1 >= BTRFS_MAX_LEVEL ||
4311                             !path->nodes[level + 1])
4312                                 return 1;
4313
4314                         if (path->locks[level + 1] || path->skip_locking) {
4315                                 level++;
4316                                 continue;
4317                         }
4318
4319                         slot = btrfs_header_nritems(c) - 1;
4320                         if (level == 0)
4321                                 btrfs_item_key_to_cpu(c, &cur_key, slot);
4322                         else
4323                                 btrfs_node_key_to_cpu(c, &cur_key, slot);
4324
4325                         orig_lowest = path->lowest_level;
4326                         btrfs_release_path(path);
4327                         path->lowest_level = level;
4328                         ret = btrfs_search_slot(NULL, root, &cur_key, path,
4329                                                 0, 0);
4330                         path->lowest_level = orig_lowest;
4331                         if (ret < 0)
4332                                 return ret;
4333
4334                         c = path->nodes[level];
4335                         slot = path->slots[level];
4336                         if (ret == 0)
4337                                 slot++;
4338                         goto next;
4339                 }
4340
4341                 if (level == 0)
4342                         btrfs_item_key_to_cpu(c, key, slot);
4343                 else {
4344                         u64 gen = btrfs_node_ptr_generation(c, slot);
4345
4346                         if (gen < min_trans) {
4347                                 slot++;
4348                                 goto next;
4349                         }
4350                         btrfs_node_key_to_cpu(c, key, slot);
4351                 }
4352                 return 0;
4353         }
4354         return 1;
4355 }
4356
4357 /*
4358  * search the tree again to find a leaf with greater keys
4359  * returns 0 if it found something or 1 if there are no greater leaves.
4360  * returns < 0 on io errors.
4361  */
4362 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
4363 {
4364         return btrfs_next_old_leaf(root, path, 0);
4365 }
4366
4367 int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
4368                         u64 time_seq)
4369 {
4370         int slot;
4371         int level;
4372         struct extent_buffer *c;
4373         struct extent_buffer *next;
4374         struct btrfs_key key;
4375         u32 nritems;
4376         int ret;
4377         int i;
4378
4379         nritems = btrfs_header_nritems(path->nodes[0]);
4380         if (nritems == 0)
4381                 return 1;
4382
4383         btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
4384 again:
4385         level = 1;
4386         next = NULL;
4387         btrfs_release_path(path);
4388
4389         path->keep_locks = 1;
4390
4391         if (time_seq)
4392                 ret = btrfs_search_old_slot(root, &key, path, time_seq);
4393         else
4394                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4395         path->keep_locks = 0;
4396
4397         if (ret < 0)
4398                 return ret;
4399
4400         nritems = btrfs_header_nritems(path->nodes[0]);
4401         /*
4402          * by releasing the path above we dropped all our locks.  A balance
4403          * could have added more items next to the key that used to be
4404          * at the very end of the block.  So, check again here and
4405          * advance the path if there are now more items available.
4406          */
4407         if (nritems > 0 && path->slots[0] < nritems - 1) {
4408                 if (ret == 0)
4409                         path->slots[0]++;
4410                 ret = 0;
4411                 goto done;
4412         }
4413         /*
4414          * So the above check misses one case:
4415          * - after releasing the path above, someone has removed the item that
4416          *   used to be at the very end of the block, and balance between leafs
4417          *   gets another one with bigger key.offset to replace it.
4418          *
4419          * This one should be returned as well, or we can get leaf corruption
4420          * later(esp. in __btrfs_drop_extents()).
4421          *
4422          * And a bit more explanation about this check,
4423          * with ret > 0, the key isn't found, the path points to the slot
4424          * where it should be inserted, so the path->slots[0] item must be the
4425          * bigger one.
4426          */
4427         if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
4428                 ret = 0;
4429                 goto done;
4430         }
4431
4432         while (level < BTRFS_MAX_LEVEL) {
4433                 if (!path->nodes[level]) {
4434                         ret = 1;
4435                         goto done;
4436                 }
4437
4438                 slot = path->slots[level] + 1;
4439                 c = path->nodes[level];
4440                 if (slot >= btrfs_header_nritems(c)) {
4441                         level++;
4442                         if (level == BTRFS_MAX_LEVEL) {
4443                                 ret = 1;
4444                                 goto done;
4445                         }
4446                         continue;
4447                 }
4448
4449
4450                 /*
4451                  * Our current level is where we're going to start from, and to
4452                  * make sure lockdep doesn't complain we need to drop our locks
4453                  * and nodes from 0 to our current level.
4454                  */
4455                 for (i = 0; i < level; i++) {
4456                         if (path->locks[level]) {
4457                                 btrfs_tree_read_unlock(path->nodes[i]);
4458                                 path->locks[i] = 0;
4459                         }
4460                         free_extent_buffer(path->nodes[i]);
4461                         path->nodes[i] = NULL;
4462                 }
4463
4464                 next = c;
4465                 ret = read_block_for_search(root, path, &next, level,
4466                                             slot, &key);
4467                 if (ret == -EAGAIN)
4468                         goto again;
4469
4470                 if (ret < 0) {
4471                         btrfs_release_path(path);
4472                         goto done;
4473                 }
4474
4475                 if (!path->skip_locking) {
4476                         ret = btrfs_try_tree_read_lock(next);
4477                         if (!ret && time_seq) {
4478                                 /*
4479                                  * If we don't get the lock, we may be racing
4480                                  * with push_leaf_left, holding that lock while
4481                                  * itself waiting for the leaf we've currently
4482                                  * locked. To solve this situation, we give up
4483                                  * on our lock and cycle.
4484                                  */
4485                                 free_extent_buffer(next);
4486                                 btrfs_release_path(path);
4487                                 cond_resched();
4488                                 goto again;
4489                         }
4490                         if (!ret)
4491                                 btrfs_tree_read_lock(next);
4492                 }
4493                 break;
4494         }
4495         path->slots[level] = slot;
4496         while (1) {
4497                 level--;
4498                 path->nodes[level] = next;
4499                 path->slots[level] = 0;
4500                 if (!path->skip_locking)
4501                         path->locks[level] = BTRFS_READ_LOCK;
4502                 if (!level)
4503                         break;
4504
4505                 ret = read_block_for_search(root, path, &next, level,
4506                                             0, &key);
4507                 if (ret == -EAGAIN)
4508                         goto again;
4509
4510                 if (ret < 0) {
4511                         btrfs_release_path(path);
4512                         goto done;
4513                 }
4514
4515                 if (!path->skip_locking)
4516                         btrfs_tree_read_lock(next);
4517         }
4518         ret = 0;
4519 done:
4520         unlock_up(path, 0, 1, 0, NULL);
4521
4522         return ret;
4523 }
4524
4525 /*
4526  * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
4527  * searching until it gets past min_objectid or finds an item of 'type'
4528  *
4529  * returns 0 if something is found, 1 if nothing was found and < 0 on error
4530  */
4531 int btrfs_previous_item(struct btrfs_root *root,
4532                         struct btrfs_path *path, u64 min_objectid,
4533                         int type)
4534 {
4535         struct btrfs_key found_key;
4536         struct extent_buffer *leaf;
4537         u32 nritems;
4538         int ret;
4539
4540         while (1) {
4541                 if (path->slots[0] == 0) {
4542                         ret = btrfs_prev_leaf(root, path);
4543                         if (ret != 0)
4544                                 return ret;
4545                 } else {
4546                         path->slots[0]--;
4547                 }
4548                 leaf = path->nodes[0];
4549                 nritems = btrfs_header_nritems(leaf);
4550                 if (nritems == 0)
4551                         return 1;
4552                 if (path->slots[0] == nritems)
4553                         path->slots[0]--;
4554
4555                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
4556                 if (found_key.objectid < min_objectid)
4557                         break;
4558                 if (found_key.type == type)
4559                         return 0;
4560                 if (found_key.objectid == min_objectid &&
4561                     found_key.type < type)
4562                         break;
4563         }
4564         return 1;
4565 }
4566
4567 /*
4568  * search in extent tree to find a previous Metadata/Data extent item with
4569  * min objecitd.
4570  *
4571  * returns 0 if something is found, 1 if nothing was found and < 0 on error
4572  */
4573 int btrfs_previous_extent_item(struct btrfs_root *root,
4574                         struct btrfs_path *path, u64 min_objectid)
4575 {
4576         struct btrfs_key found_key;
4577         struct extent_buffer *leaf;
4578         u32 nritems;
4579         int ret;
4580
4581         while (1) {
4582                 if (path->slots[0] == 0) {
4583                         ret = btrfs_prev_leaf(root, path);
4584                         if (ret != 0)
4585                                 return ret;
4586                 } else {
4587                         path->slots[0]--;
4588                 }
4589                 leaf = path->nodes[0];
4590                 nritems = btrfs_header_nritems(leaf);
4591                 if (nritems == 0)
4592                         return 1;
4593                 if (path->slots[0] == nritems)
4594                         path->slots[0]--;
4595
4596                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
4597                 if (found_key.objectid < min_objectid)
4598                         break;
4599                 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
4600                     found_key.type == BTRFS_METADATA_ITEM_KEY)
4601                         return 0;
4602                 if (found_key.objectid == min_objectid &&
4603                     found_key.type < BTRFS_EXTENT_ITEM_KEY)
4604                         break;
4605         }
4606         return 1;
4607 }