fs/btrfs/ctree.c

   1 /*
   2  * Copyright (C) 2007,2008 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/sched.h>
  20 #include <linux/slab.h>
  21 #include <linux/rbtree.h>
  22 #include <linux/mm.h>
  23 #include "ctree.h"
  24 #include "disk-io.h"
  25 #include "transaction.h"
  26 #include "print-tree.h"
  27 #include "locking.h"
  28
  29 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
  30                       *root, struct btrfs_path *path, int level);
  31 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  32                       const struct btrfs_key *ins_key, struct btrfs_path *path,
  33                       int data_size, int extend);
  34 static int push_node_left(struct btrfs_trans_handle *trans,
  35                           struct btrfs_fs_info *fs_info,
  36                           struct extent_buffer *dst,
  37                           struct extent_buffer *src, int empty);
  38 static int balance_node_right(struct btrfs_trans_handle *trans,
  39                               struct btrfs_fs_info *fs_info,
  40                               struct extent_buffer *dst_buf,
  41                               struct extent_buffer *src_buf);
  42 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
  43                     int level, int slot);
  44 static int tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
  45                                  struct extent_buffer *eb);
  46
  47 struct btrfs_path *btrfs_alloc_path(void)
  48 {
  49         return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
  50 }
  51
  52 /*
  53  * set all locked nodes in the path to blocking locks.  This should
  54  * be done before scheduling
  55  */
  56 noinline void btrfs_set_path_blocking(struct btrfs_path *p)
  57 {
  58         int i;
  59         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
  60                 if (!p->nodes[i] || !p->locks[i])
  61                         continue;
  62                 btrfs_set_lock_blocking_rw(p->nodes[i], p->locks[i]);
  63                 if (p->locks[i] == BTRFS_READ_LOCK)
  64                         p->locks[i] = BTRFS_READ_LOCK_BLOCKING;
  65                 else if (p->locks[i] == BTRFS_WRITE_LOCK)
  66                         p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING;
  67         }
  68 }
  69
  70 /*
  71  * reset all the locked nodes in the patch to spinning locks.
  72  *
  73  * held is used to keep lockdep happy, when lockdep is enabled
  74  * we set held to a blocking lock before we go around and
  75  * retake all the spinlocks in the path.  You can safely use NULL
  76  * for held
  77  */
  78 noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
  79                                         struct extent_buffer *held, int held_rw)
  80 {
  81         int i;
  82
  83         if (held) {
  84                 btrfs_set_lock_blocking_rw(held, held_rw);
  85                 if (held_rw == BTRFS_WRITE_LOCK)
  86                         held_rw = BTRFS_WRITE_LOCK_BLOCKING;
  87                 else if (held_rw == BTRFS_READ_LOCK)
  88                         held_rw = BTRFS_READ_LOCK_BLOCKING;
  89         }
  90         btrfs_set_path_blocking(p);
  91
  92         for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
  93                 if (p->nodes[i] && p->locks[i]) {
  94                         btrfs_clear_lock_blocking_rw(p->nodes[i], p->locks[i]);
  95                         if (p->locks[i] == BTRFS_WRITE_LOCK_BLOCKING)
  96                                 p->locks[i] = BTRFS_WRITE_LOCK;
  97                         else if (p->locks[i] == BTRFS_READ_LOCK_BLOCKING)
  98                                 p->locks[i] = BTRFS_READ_LOCK;
  99                 }
 100         }
 101
 102         if (held)
 103                 btrfs_clear_lock_blocking_rw(held, held_rw);
 104 }
 105
 106 /* this also releases the path */
 107 void btrfs_free_path(struct btrfs_path *p)
 108 {
 109         if (!p)
 110                 return;
 111         btrfs_release_path(p);
 112         kmem_cache_free(btrfs_path_cachep, p);
 113 }
 114
 115 /*
 116  * path release drops references on the extent buffers in the path
 117  * and it drops any locks held by this path
 118  *
 119  * It is safe to call this on paths that no locks or extent buffers held.
 120  */
 121 noinline void btrfs_release_path(struct btrfs_path *p)
 122 {
 123         int i;
 124
 125         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
 126                 p->slots[i] = 0;
 127                 if (!p->nodes[i])
 128                         continue;
 129                 if (p->locks[i]) {
 130                         btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
 131                         p->locks[i] = 0;
 132                 }
 133                 free_extent_buffer(p->nodes[i]);
 134                 p->nodes[i] = NULL;
 135         }
 136 }
 137
 138 /*
 139  * safely gets a reference on the root node of a tree.  A lock
 140  * is not taken, so a concurrent writer may put a different node
 141  * at the root of the tree.  See btrfs_lock_root_node for the
 142  * looping required.
 143  *
 144  * The extent buffer returned by this has a reference taken, so
 145  * it won't disappear.  It may stop being the root of the tree
 146  * at any time because there are no locks held.
 147  */
 148 struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
 149 {
 150         struct extent_buffer *eb;
 151
 152         while (1) {
 153                 rcu_read_lock();
 154                 eb = rcu_dereference(root->node);
 155
 156                 /*
 157                  * RCU really hurts here, we could free up the root node because
 158                  * it was COWed but we may not get the new root node yet so do
 159                  * the inc_not_zero dance and if it doesn't work then
 160                  * synchronize_rcu and try again.
 161                  */
 162                 if (atomic_inc_not_zero(&eb->refs)) {
 163                         rcu_read_unlock();
 164                         break;
 165                 }
 166                 rcu_read_unlock();
 167                 synchronize_rcu();
 168         }
 169         return eb;
 170 }
 171
 172 /* loop around taking references on and locking the root node of the
 173  * tree until you end up with a lock on the root.  A locked buffer
 174  * is returned, with a reference held.
 175  */
 176 struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
 177 {
 178         struct extent_buffer *eb;
 179
 180         while (1) {
 181                 eb = btrfs_root_node(root);
 182                 btrfs_tree_lock(eb);
 183                 if (eb == root->node)
 184                         break;
 185                 btrfs_tree_unlock(eb);
 186                 free_extent_buffer(eb);
 187         }
 188         return eb;
 189 }
 190
 191 /* loop around taking references on and locking the root node of the
 192  * tree until you end up with a lock on the root.  A locked buffer
 193  * is returned, with a reference held.
 194  */
 195 static struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
 196 {
 197         struct extent_buffer *eb;
 198
 199         while (1) {
 200                 eb = btrfs_root_node(root);
 201                 btrfs_tree_read_lock(eb);
 202                 if (eb == root->node)
 203                         break;
 204                 btrfs_tree_read_unlock(eb);
 205                 free_extent_buffer(eb);
 206         }
 207         return eb;
 208 }
 209
 210 /* cowonly root (everything not a reference counted cow subvolume), just get
 211  * put onto a simple dirty list.  transaction.c walks this to make sure they
 212  * get properly updated on disk.
 213  */
 214 static void add_root_to_dirty_list(struct btrfs_root *root)
 215 {
 216         struct btrfs_fs_info *fs_info = root->fs_info;
 217
 218         if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
 219             !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
 220                 return;
 221
 222         spin_lock(&fs_info->trans_lock);
 223         if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
 224                 /* Want the extent tree to be the last on the list */
 225                 if (root->objectid == BTRFS_EXTENT_TREE_OBJECTID)
 226                         list_move_tail(&root->dirty_list,
 227                                        &fs_info->dirty_cowonly_roots);
 228                 else
 229                         list_move(&root->dirty_list,
 230                                   &fs_info->dirty_cowonly_roots);
 231         }
 232         spin_unlock(&fs_info->trans_lock);
 233 }
 234
 235 /*
 236  * used by snapshot creation to make a copy of a root for a tree with
 237  * a given objectid.  The buffer with the new root node is returned in
 238  * cow_ret, and this func returns zero on success or a negative error code.
 239  */
 240 int btrfs_copy_root(struct btrfs_trans_handle *trans,
 241                       struct btrfs_root *root,
 242                       struct extent_buffer *buf,
 243                       struct extent_buffer **cow_ret, u64 new_root_objectid)
 244 {
 245         struct btrfs_fs_info *fs_info = root->fs_info;
 246         struct extent_buffer *cow;
 247         int ret = 0;
 248         int level;
 249         struct btrfs_disk_key disk_key;
 250
 251         WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 252                 trans->transid != fs_info->running_transaction->transid);
 253         WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 254                 trans->transid != root->last_trans);
 255
 256         level = btrfs_header_level(buf);
 257         if (level == 0)
 258                 btrfs_item_key(buf, &disk_key, 0);
 259         else
 260                 btrfs_node_key(buf, &disk_key, 0);
 261
 262         cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
 263                         &disk_key, level, buf->start, 0);
 264         if (IS_ERR(cow))
 265                 return PTR_ERR(cow);
 266
 267         copy_extent_buffer_full(cow, buf);
 268         btrfs_set_header_bytenr(cow, cow->start);
 269         btrfs_set_header_generation(cow, trans->transid);
 270         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
 271         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
 272                                      BTRFS_HEADER_FLAG_RELOC);
 273         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 274                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
 275         else
 276                 btrfs_set_header_owner(cow, new_root_objectid);
 277
 278         write_extent_buffer_fsid(cow, fs_info->fsid);
 279
 280         WARN_ON(btrfs_header_generation(buf) > trans->transid);
 281         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
 282                 ret = btrfs_inc_ref(trans, root, cow, 1);
 283         else
 284                 ret = btrfs_inc_ref(trans, root, cow, 0);
 285
 286         if (ret)
 287                 return ret;
 288
 289         btrfs_mark_buffer_dirty(cow);
 290         *cow_ret = cow;
 291         return 0;
 292 }
 293
 294 enum mod_log_op {
 295         MOD_LOG_KEY_REPLACE,
 296         MOD_LOG_KEY_ADD,
 297         MOD_LOG_KEY_REMOVE,
 298         MOD_LOG_KEY_REMOVE_WHILE_FREEING,
 299         MOD_LOG_KEY_REMOVE_WHILE_MOVING,
 300         MOD_LOG_MOVE_KEYS,
 301         MOD_LOG_ROOT_REPLACE,
 302 };
 303
 304 struct tree_mod_move {
 305         int dst_slot;
 306         int nr_items;
 307 };
 308
 309 struct tree_mod_root {
 310         u64 logical;
 311         u8 level;
 312 };
 313
 314 struct tree_mod_elem {
 315         struct rb_node node;
 316         u64 logical;
 317         u64 seq;
 318         enum mod_log_op op;
 319
 320         /* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
 321         int slot;
 322
 323         /* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
 324         u64 generation;
 325
 326         /* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
 327         struct btrfs_disk_key key;
 328         u64 blockptr;
 329
 330         /* this is used for op == MOD_LOG_MOVE_KEYS */
 331         struct tree_mod_move move;
 332
 333         /* this is used for op == MOD_LOG_ROOT_REPLACE */
 334         struct tree_mod_root old_root;
 335 };
 336
 337 static inline void tree_mod_log_read_lock(struct btrfs_fs_info *fs_info)
 338 {
 339         read_lock(&fs_info->tree_mod_log_lock);
 340 }
 341
 342 static inline void tree_mod_log_read_unlock(struct btrfs_fs_info *fs_info)
 343 {
 344         read_unlock(&fs_info->tree_mod_log_lock);
 345 }
 346
 347 static inline void tree_mod_log_write_lock(struct btrfs_fs_info *fs_info)
 348 {
 349         write_lock(&fs_info->tree_mod_log_lock);
 350 }
 351
 352 static inline void tree_mod_log_write_unlock(struct btrfs_fs_info *fs_info)
 353 {
 354         write_unlock(&fs_info->tree_mod_log_lock);
 355 }
 356
 357 /*
 358  * Pull a new tree mod seq number for our operation.
 359  */
 360 static inline u64 btrfs_inc_tree_mod_seq(struct btrfs_fs_info *fs_info)
 361 {
 362         return atomic64_inc_return(&fs_info->tree_mod_seq);
 363 }
 364
 365 /*
 366  * This adds a new blocker to the tree mod log's blocker list if the @elem
 367  * passed does not already have a sequence number set. So when a caller expects
 368  * to record tree modifications, it should ensure to set elem->seq to zero
 369  * before calling btrfs_get_tree_mod_seq.
 370  * Returns a fresh, unused tree log modification sequence number, even if no new
 371  * blocker was added.
 372  */
 373 u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
 374                            struct seq_list *elem)
 375 {
 376         tree_mod_log_write_lock(fs_info);
 377         spin_lock(&fs_info->tree_mod_seq_lock);
 378         if (!elem->seq) {
 379                 elem->seq = btrfs_inc_tree_mod_seq(fs_info);
 380                 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
 381         }
 382         spin_unlock(&fs_info->tree_mod_seq_lock);
 383         tree_mod_log_write_unlock(fs_info);
 384
 385         return elem->seq;
 386 }
 387
 388 void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
 389                             struct seq_list *elem)
 390 {
 391         struct rb_root *tm_root;
 392         struct rb_node *node;
 393         struct rb_node *next;
 394         struct seq_list *cur_elem;
 395         struct tree_mod_elem *tm;
 396         u64 min_seq = (u64)-1;
 397         u64 seq_putting = elem->seq;
 398
 399         if (!seq_putting)
 400                 return;
 401
 402         spin_lock(&fs_info->tree_mod_seq_lock);
 403         list_del(&elem->list);
 404         elem->seq = 0;
 405
 406         list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) {
 407                 if (cur_elem->seq < min_seq) {
 408                         if (seq_putting > cur_elem->seq) {
 409                                 /*
 410                                  * blocker with lower sequence number exists, we
 411                                  * cannot remove anything from the log
 412                                  */
 413                                 spin_unlock(&fs_info->tree_mod_seq_lock);
 414                                 return;
 415                         }
 416                         min_seq = cur_elem->seq;
 417                 }
 418         }
 419         spin_unlock(&fs_info->tree_mod_seq_lock);
 420
 421         /*
 422          * anything that's lower than the lowest existing (read: blocked)
 423          * sequence number can be removed from the tree.
 424          */
 425         tree_mod_log_write_lock(fs_info);
 426         tm_root = &fs_info->tree_mod_log;
 427         for (node = rb_first(tm_root); node; node = next) {
 428                 next = rb_next(node);
 429                 tm = rb_entry(node, struct tree_mod_elem, node);
 430                 if (tm->seq > min_seq)
 431                         continue;
 432                 rb_erase(node, tm_root);
 433                 kfree(tm);
 434         }
 435         tree_mod_log_write_unlock(fs_info);
 436 }
 437
 438 /*
 439  * key order of the log:
 440  *       node/leaf start address -> sequence
 441  *
 442  * The 'start address' is the logical address of the *new* root node
 443  * for root replace operations, or the logical address of the affected
 444  * block for all other operations.
 445  *
 446  * Note: must be called with write lock (tree_mod_log_write_lock).
 447  */
 448 static noinline int
 449 __tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
 450 {
 451         struct rb_root *tm_root;
 452         struct rb_node **new;
 453         struct rb_node *parent = NULL;
 454         struct tree_mod_elem *cur;
 455
 456         tm->seq = btrfs_inc_tree_mod_seq(fs_info);
 457
 458         tm_root = &fs_info->tree_mod_log;
 459         new = &tm_root->rb_node;
 460         while (*new) {
 461                 cur = rb_entry(*new, struct tree_mod_elem, node);
 462                 parent = *new;
 463                 if (cur->logical < tm->logical)
 464                         new = &((*new)->rb_left);
 465                 else if (cur->logical > tm->logical)
 466                         new = &((*new)->rb_right);
 467                 else if (cur->seq < tm->seq)
 468                         new = &((*new)->rb_left);
 469                 else if (cur->seq > tm->seq)
 470                         new = &((*new)->rb_right);
 471                 else
 472                         return -EEXIST;
 473         }
 474
 475         rb_link_node(&tm->node, parent, new);
 476         rb_insert_color(&tm->node, tm_root);
 477         return 0;
 478 }
 479
 480 /*
 481  * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it
 482  * returns zero with the tree_mod_log_lock acquired. The caller must hold
 483  * this until all tree mod log insertions are recorded in the rb tree and then
 484  * call tree_mod_log_write_unlock() to release.
 485  */
 486 static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
 487                                     struct extent_buffer *eb) {
 488         smp_mb();
 489         if (list_empty(&(fs_info)->tree_mod_seq_list))
 490                 return 1;
 491         if (eb && btrfs_header_level(eb) == 0)
 492                 return 1;
 493
 494         tree_mod_log_write_lock(fs_info);
 495         if (list_empty(&(fs_info)->tree_mod_seq_list)) {
 496                 tree_mod_log_write_unlock(fs_info);
 497                 return 1;
 498         }
 499
 500         return 0;
 501 }
 502
 503 /* Similar to tree_mod_dont_log, but doesn't acquire any locks. */
 504 static inline int tree_mod_need_log(const struct btrfs_fs_info *fs_info,
 505                                     struct extent_buffer *eb)
 506 {
 507         smp_mb();
 508         if (list_empty(&(fs_info)->tree_mod_seq_list))
 509                 return 0;
 510         if (eb && btrfs_header_level(eb) == 0)
 511                 return 0;
 512
 513         return 1;
 514 }
 515
 516 static struct tree_mod_elem *
 517 alloc_tree_mod_elem(struct extent_buffer *eb, int slot,
 518                     enum mod_log_op op, gfp_t flags)
 519 {
 520         struct tree_mod_elem *tm;
 521
 522         tm = kzalloc(sizeof(*tm), flags);
 523         if (!tm)
 524                 return NULL;
 525
 526         tm->logical = eb->start;
 527         if (op != MOD_LOG_KEY_ADD) {
 528                 btrfs_node_key(eb, &tm->key, slot);
 529                 tm->blockptr = btrfs_node_blockptr(eb, slot);
 530         }
 531         tm->op = op;
 532         tm->slot = slot;
 533         tm->generation = btrfs_node_ptr_generation(eb, slot);
 534         RB_CLEAR_NODE(&tm->node);
 535
 536         return tm;
 537 }
 538
 539 static noinline int
 540 tree_mod_log_insert_key(struct btrfs_fs_info *fs_info,
 541                         struct extent_buffer *eb, int slot,
 542                         enum mod_log_op op, gfp_t flags)
 543 {
 544         struct tree_mod_elem *tm;
 545         int ret;
 546
 547         if (!tree_mod_need_log(fs_info, eb))
 548                 return 0;
 549
 550         tm = alloc_tree_mod_elem(eb, slot, op, flags);
 551         if (!tm)
 552                 return -ENOMEM;
 553
 554         if (tree_mod_dont_log(fs_info, eb)) {
 555                 kfree(tm);
 556                 return 0;
 557         }
 558
 559         ret = __tree_mod_log_insert(fs_info, tm);
 560         tree_mod_log_write_unlock(fs_info);
 561         if (ret)
 562                 kfree(tm);
 563
 564         return ret;
 565 }
 566
 567 static noinline int
 568 tree_mod_log_insert_move(struct btrfs_fs_info *fs_info,
 569                          struct extent_buffer *eb, int dst_slot, int src_slot,
 570                          int nr_items)
 571 {
 572         struct tree_mod_elem *tm = NULL;
 573         struct tree_mod_elem **tm_list = NULL;
 574         int ret = 0;
 575         int i;
 576         int locked = 0;
 577
 578         if (!tree_mod_need_log(fs_info, eb))
 579                 return 0;
 580
 581         tm_list = kcalloc(nr_items, sizeof(struct tree_mod_elem *), GFP_NOFS);
 582         if (!tm_list)
 583                 return -ENOMEM;
 584
 585         tm = kzalloc(sizeof(*tm), GFP_NOFS);
 586         if (!tm) {
 587                 ret = -ENOMEM;
 588                 goto free_tms;
 589         }
 590
 591         tm->logical = eb->start;
 592         tm->slot = src_slot;
 593         tm->move.dst_slot = dst_slot;
 594         tm->move.nr_items = nr_items;
 595         tm->op = MOD_LOG_MOVE_KEYS;
 596
 597         for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
 598                 tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot,
 599                     MOD_LOG_KEY_REMOVE_WHILE_MOVING, GFP_NOFS);
 600                 if (!tm_list[i]) {
 601                         ret = -ENOMEM;
 602                         goto free_tms;
 603                 }
 604         }
 605
 606         if (tree_mod_dont_log(fs_info, eb))
 607                 goto free_tms;
 608         locked = 1;
 609
 610         /*
 611          * When we override something during the move, we log these removals.
 612          * This can only happen when we move towards the beginning of the
 613          * buffer, i.e. dst_slot < src_slot.
 614          */
 615         for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
 616                 ret = __tree_mod_log_insert(fs_info, tm_list[i]);
 617                 if (ret)
 618                         goto free_tms;
 619         }
 620
 621         ret = __tree_mod_log_insert(fs_info, tm);
 622         if (ret)
 623                 goto free_tms;
 624         tree_mod_log_write_unlock(fs_info);
 625         kfree(tm_list);
 626
 627         return 0;
 628 free_tms:
 629         for (i = 0; i < nr_items; i++) {
 630                 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
 631                         rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
 632                 kfree(tm_list[i]);
 633         }
 634         if (locked)
 635                 tree_mod_log_write_unlock(fs_info);
 636         kfree(tm_list);
 637         kfree(tm);
 638
 639         return ret;
 640 }
 641
 642 static inline int
 643 __tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
 644                        struct tree_mod_elem **tm_list,
 645                        int nritems)
 646 {
 647         int i, j;
 648         int ret;
 649
 650         for (i = nritems - 1; i >= 0; i--) {
 651                 ret = __tree_mod_log_insert(fs_info, tm_list[i]);
 652                 if (ret) {
 653                         for (j = nritems - 1; j > i; j--)
 654                                 rb_erase(&tm_list[j]->node,
 655                                          &fs_info->tree_mod_log);
 656                         return ret;
 657                 }
 658         }
 659
 660         return 0;
 661 }
 662
 663 static noinline int
 664 tree_mod_log_insert_root(struct btrfs_fs_info *fs_info,
 665                          struct extent_buffer *old_root,
 666                          struct extent_buffer *new_root,
 667                          int log_removal)
 668 {
 669         struct tree_mod_elem *tm = NULL;
 670         struct tree_mod_elem **tm_list = NULL;
 671         int nritems = 0;
 672         int ret = 0;
 673         int i;
 674
 675         if (!tree_mod_need_log(fs_info, NULL))
 676                 return 0;
 677
 678         if (log_removal && btrfs_header_level(old_root) > 0) {
 679                 nritems = btrfs_header_nritems(old_root);
 680                 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *),
 681                                   GFP_NOFS);
 682                 if (!tm_list) {
 683                         ret = -ENOMEM;
 684                         goto free_tms;
 685                 }
 686                 for (i = 0; i < nritems; i++) {
 687                         tm_list[i] = alloc_tree_mod_elem(old_root, i,
 688                             MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
 689                         if (!tm_list[i]) {
 690                                 ret = -ENOMEM;
 691                                 goto free_tms;
 692                         }
 693                 }
 694         }
 695
 696         tm = kzalloc(sizeof(*tm), GFP_NOFS);
 697         if (!tm) {
 698                 ret = -ENOMEM;
 699                 goto free_tms;
 700         }
 701
 702         tm->logical = new_root->start;
 703         tm->old_root.logical = old_root->start;
 704         tm->old_root.level = btrfs_header_level(old_root);
 705         tm->generation = btrfs_header_generation(old_root);
 706         tm->op = MOD_LOG_ROOT_REPLACE;
 707
 708         if (tree_mod_dont_log(fs_info, NULL))
 709                 goto free_tms;
 710
 711         if (tm_list)
 712                 ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
 713         if (!ret)
 714                 ret = __tree_mod_log_insert(fs_info, tm);
 715
 716         tree_mod_log_write_unlock(fs_info);
 717         if (ret)
 718                 goto free_tms;
 719         kfree(tm_list);
 720
 721         return ret;
 722
 723 free_tms:
 724         if (tm_list) {
 725                 for (i = 0; i < nritems; i++)
 726                         kfree(tm_list[i]);
 727                 kfree(tm_list);
 728         }
 729         kfree(tm);
 730
 731         return ret;
 732 }
 733
 734 static struct tree_mod_elem *
 735 __tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
 736                       int smallest)
 737 {
 738         struct rb_root *tm_root;
 739         struct rb_node *node;
 740         struct tree_mod_elem *cur = NULL;
 741         struct tree_mod_elem *found = NULL;
 742
 743         tree_mod_log_read_lock(fs_info);
 744         tm_root = &fs_info->tree_mod_log;
 745         node = tm_root->rb_node;
 746         while (node) {
 747                 cur = rb_entry(node, struct tree_mod_elem, node);
 748                 if (cur->logical < start) {
 749                         node = node->rb_left;
 750                 } else if (cur->logical > start) {
 751                         node = node->rb_right;
 752                 } else if (cur->seq < min_seq) {
 753                         node = node->rb_left;
 754                 } else if (!smallest) {
 755                         /* we want the node with the highest seq */
 756                         if (found)
 757                                 BUG_ON(found->seq > cur->seq);
 758                         found = cur;
 759                         node = node->rb_left;
 760                 } else if (cur->seq > min_seq) {
 761                         /* we want the node with the smallest seq */
 762                         if (found)
 763                                 BUG_ON(found->seq < cur->seq);
 764                         found = cur;
 765                         node = node->rb_right;
 766                 } else {
 767                         found = cur;
 768                         break;
 769                 }
 770         }
 771         tree_mod_log_read_unlock(fs_info);
 772
 773         return found;
 774 }
 775
 776 /*
 777  * this returns the element from the log with the smallest time sequence
 778  * value that's in the log (the oldest log item). any element with a time
 779  * sequence lower than min_seq will be ignored.
 780  */
 781 static struct tree_mod_elem *
 782 tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
 783                            u64 min_seq)
 784 {
 785         return __tree_mod_log_search(fs_info, start, min_seq, 1);
 786 }
 787
 788 /*
 789  * this returns the element from the log with the largest time sequence
 790  * value that's in the log (the most recent log item). any element with
 791  * a time sequence lower than min_seq will be ignored.
 792  */
 793 static struct tree_mod_elem *
 794 tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
 795 {
 796         return __tree_mod_log_search(fs_info, start, min_seq, 0);
 797 }
 798
 799 static noinline int
 800 tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
 801                      struct extent_buffer *src, unsigned long dst_offset,
 802                      unsigned long src_offset, int nr_items)
 803 {
 804         int ret = 0;
 805         struct tree_mod_elem **tm_list = NULL;
 806         struct tree_mod_elem **tm_list_add, **tm_list_rem;
 807         int i;
 808         int locked = 0;
 809
 810         if (!tree_mod_need_log(fs_info, NULL))
 811                 return 0;
 812
 813         if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
 814                 return 0;
 815
 816         tm_list = kcalloc(nr_items * 2, sizeof(struct tree_mod_elem *),
 817                           GFP_NOFS);
 818         if (!tm_list)
 819                 return -ENOMEM;
 820
 821         tm_list_add = tm_list;
 822         tm_list_rem = tm_list + nr_items;
 823         for (i = 0; i < nr_items; i++) {
 824                 tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset,
 825                     MOD_LOG_KEY_REMOVE, GFP_NOFS);
 826                 if (!tm_list_rem[i]) {
 827                         ret = -ENOMEM;
 828                         goto free_tms;
 829                 }
 830
 831                 tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset,
 832                     MOD_LOG_KEY_ADD, GFP_NOFS);
 833                 if (!tm_list_add[i]) {
 834                         ret = -ENOMEM;
 835                         goto free_tms;
 836                 }
 837         }
 838
 839         if (tree_mod_dont_log(fs_info, NULL))
 840                 goto free_tms;
 841         locked = 1;
 842
 843         for (i = 0; i < nr_items; i++) {
 844                 ret = __tree_mod_log_insert(fs_info, tm_list_rem[i]);
 845                 if (ret)
 846                         goto free_tms;
 847                 ret = __tree_mod_log_insert(fs_info, tm_list_add[i]);
 848                 if (ret)
 849                         goto free_tms;
 850         }
 851
 852         tree_mod_log_write_unlock(fs_info);
 853         kfree(tm_list);
 854
 855         return 0;
 856
 857 free_tms:
 858         for (i = 0; i < nr_items * 2; i++) {
 859                 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
 860                         rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
 861                 kfree(tm_list[i]);
 862         }
 863         if (locked)
 864                 tree_mod_log_write_unlock(fs_info);
 865         kfree(tm_list);
 866
 867         return ret;
 868 }
 869
 870 static inline void
 871 tree_mod_log_eb_move(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
 872                      int dst_offset, int src_offset, int nr_items)
 873 {
 874         int ret;
 875         ret = tree_mod_log_insert_move(fs_info, dst, dst_offset, src_offset,
 876                                        nr_items);
 877         BUG_ON(ret < 0);
 878 }
 879
 880 static noinline void
 881 tree_mod_log_set_node_key(struct btrfs_fs_info *fs_info,
 882                           struct extent_buffer *eb, int slot, int atomic)
 883 {
 884         int ret;
 885
 886         ret = tree_mod_log_insert_key(fs_info, eb, slot,
 887                                         MOD_LOG_KEY_REPLACE,
 888                                         atomic ? GFP_ATOMIC : GFP_NOFS);
 889         BUG_ON(ret < 0);
 890 }
 891
 892 static noinline int
 893 tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, struct extent_buffer *eb)
 894 {
 895         struct tree_mod_elem **tm_list = NULL;
 896         int nritems = 0;
 897         int i;
 898         int ret = 0;
 899
 900         if (btrfs_header_level(eb) == 0)
 901                 return 0;
 902
 903         if (!tree_mod_need_log(fs_info, NULL))
 904                 return 0;
 905
 906         nritems = btrfs_header_nritems(eb);
 907         tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *), GFP_NOFS);
 908         if (!tm_list)
 909                 return -ENOMEM;
 910
 911         for (i = 0; i < nritems; i++) {
 912                 tm_list[i] = alloc_tree_mod_elem(eb, i,
 913                     MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
 914                 if (!tm_list[i]) {
 915                         ret = -ENOMEM;
 916                         goto free_tms;
 917                 }
 918         }
 919
 920         if (tree_mod_dont_log(fs_info, eb))
 921                 goto free_tms;
 922
 923         ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
 924         tree_mod_log_write_unlock(fs_info);
 925         if (ret)
 926                 goto free_tms;
 927         kfree(tm_list);
 928
 929         return 0;
 930
 931 free_tms:
 932         for (i = 0; i < nritems; i++)
 933                 kfree(tm_list[i]);
 934         kfree(tm_list);
 935
 936         return ret;
 937 }
 938
 939 static noinline void
 940 tree_mod_log_set_root_pointer(struct btrfs_root *root,
 941                               struct extent_buffer *new_root_node,
 942                               int log_removal)
 943 {
 944         int ret;
 945         ret = tree_mod_log_insert_root(root->fs_info, root->node,
 946                                        new_root_node, log_removal);
 947         BUG_ON(ret < 0);
 948 }
 949
 950 /*
 951  * check if the tree block can be shared by multiple trees
 952  */
 953 int btrfs_block_can_be_shared(struct btrfs_root *root,
 954                               struct extent_buffer *buf)
 955 {
 956         /*
 957          * Tree blocks not in reference counted trees and tree roots
 958          * are never shared. If a block was allocated after the last
 959          * snapshot and the block was not allocated by tree relocation,
 960          * we know the block is not shared.
 961          */
 962         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 963             buf != root->node && buf != root->commit_root &&
 964             (btrfs_header_generation(buf) <=
 965              btrfs_root_last_snapshot(&root->root_item) ||
 966              btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 967                 return 1;
 968 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
 969         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 970             btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
 971                 return 1;
 972 #endif
 973         return 0;
 974 }
 975
 976 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
 977                                        struct btrfs_root *root,
 978                                        struct extent_buffer *buf,
 979                                        struct extent_buffer *cow,
 980                                        int *last_ref)
 981 {
 982         struct btrfs_fs_info *fs_info = root->fs_info;
 983         u64 refs;
 984         u64 owner;
 985         u64 flags;
 986         u64 new_flags = 0;
 987         int ret;
 988
 989         /*
 990          * Backrefs update rules:
 991          *
 992          * Always use full backrefs for extent pointers in tree block
 993          * allocated by tree relocation.
 994          *
 995          * If a shared tree block is no longer referenced by its owner
 996          * tree (btrfs_header_owner(buf) == root->root_key.objectid),
 997          * use full backrefs for extent pointers in tree block.
 998          *
 999          * If a tree block is been relocating
1000          * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
1001          * use full backrefs for extent pointers in tree block.
1002          * The reason for this is some operations (such as drop tree)
1003          * are only allowed for blocks use full backrefs.
1004          */
1005
1006         if (btrfs_block_can_be_shared(root, buf)) {
1007                 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
1008                                                btrfs_header_level(buf), 1,
1009                                                &refs, &flags);
1010                 if (ret)
1011                         return ret;
1012                 if (refs == 0) {
1013                         ret = -EROFS;
1014                         btrfs_handle_fs_error(fs_info, ret, NULL);
1015                         return ret;
1016                 }
1017         } else {
1018                 refs = 1;
1019                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1020                     btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1021                         flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
1022                 else
1023                         flags = 0;
1024         }
1025
1026         owner = btrfs_header_owner(buf);
1027         BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
1028                !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
1029
1030         if (refs > 1) {
1031                 if ((owner == root->root_key.objectid ||
1032                      root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
1033                     !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
1034                         ret = btrfs_inc_ref(trans, root, buf, 1);
1035                         if (ret)
1036                                 return ret;
1037
1038                         if (root->root_key.objectid ==
1039                             BTRFS_TREE_RELOC_OBJECTID) {
1040                                 ret = btrfs_dec_ref(trans, root, buf, 0);
1041                                 if (ret)
1042                                         return ret;
1043                                 ret = btrfs_inc_ref(trans, root, cow, 1);
1044                                 if (ret)
1045                                         return ret;
1046                         }
1047                         new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
1048                 } else {
1049
1050                         if (root->root_key.objectid ==
1051                             BTRFS_TREE_RELOC_OBJECTID)
1052                                 ret = btrfs_inc_ref(trans, root, cow, 1);
1053                         else
1054                                 ret = btrfs_inc_ref(trans, root, cow, 0);
1055                         if (ret)
1056                                 return ret;
1057                 }
1058                 if (new_flags != 0) {
1059                         int level = btrfs_header_level(buf);
1060
1061                         ret = btrfs_set_disk_extent_flags(trans, fs_info,
1062                                                           buf->start,
1063                                                           buf->len,
1064                                                           new_flags, level, 0);
1065                         if (ret)
1066                                 return ret;
1067                 }
1068         } else {
1069                 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
1070                         if (root->root_key.objectid ==
1071                             BTRFS_TREE_RELOC_OBJECTID)
1072                                 ret = btrfs_inc_ref(trans, root, cow, 1);
1073                         else
1074                                 ret = btrfs_inc_ref(trans, root, cow, 0);
1075                         if (ret)
1076                                 return ret;
1077                         ret = btrfs_dec_ref(trans, root, buf, 1);
1078                         if (ret)
1079                                 return ret;
1080                 }
1081                 clean_tree_block(fs_info, buf);
1082                 *last_ref = 1;
1083         }
1084         return 0;
1085 }
1086
1087 /*
1088  * does the dirty work in cow of a single block.  The parent block (if
1089  * supplied) is updated to point to the new cow copy.  The new buffer is marked
1090  * dirty and returned locked.  If you modify the block it needs to be marked
1091  * dirty again.
1092  *
1093  * search_start -- an allocation hint for the new block
1094  *
1095  * empty_size -- a hint that you plan on doing more cow.  This is the size in
1096  * bytes the allocator should try to find free next to the block it returns.
1097  * This is just a hint and may be ignored by the allocator.
1098  */
1099 static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
1100                              struct btrfs_root *root,
1101                              struct extent_buffer *buf,
1102                              struct extent_buffer *parent, int parent_slot,
1103                              struct extent_buffer **cow_ret,
1104                              u64 search_start, u64 empty_size)
1105 {
1106         struct btrfs_fs_info *fs_info = root->fs_info;
1107         struct btrfs_disk_key disk_key;
1108         struct extent_buffer *cow;
1109         int level, ret;
1110         int last_ref = 0;
1111         int unlock_orig = 0;
1112         u64 parent_start = 0;
1113
1114         if (*cow_ret == buf)
1115                 unlock_orig = 1;
1116
1117         btrfs_assert_tree_locked(buf);
1118
1119         WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
1120                 trans->transid != fs_info->running_transaction->transid);
1121         WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
1122                 trans->transid != root->last_trans);
1123
1124         level = btrfs_header_level(buf);
1125
1126         if (level == 0)
1127                 btrfs_item_key(buf, &disk_key, 0);
1128         else
1129                 btrfs_node_key(buf, &disk_key, 0);
1130
1131         if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
1132                 parent_start = parent->start;
1133
1134         cow = btrfs_alloc_tree_block(trans, root, parent_start,
1135                         root->root_key.objectid, &disk_key, level,
1136                         search_start, empty_size);
1137         if (IS_ERR(cow))
1138                 return PTR_ERR(cow);
1139
1140         /* cow is set to blocking by btrfs_init_new_buffer */
1141
1142         copy_extent_buffer_full(cow, buf);
1143         btrfs_set_header_bytenr(cow, cow->start);
1144         btrfs_set_header_generation(cow, trans->transid);
1145         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
1146         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
1147                                      BTRFS_HEADER_FLAG_RELOC);
1148         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1149                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
1150         else
1151                 btrfs_set_header_owner(cow, root->root_key.objectid);
1152
1153         write_extent_buffer_fsid(cow, fs_info->fsid);
1154
1155         ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
1156         if (ret) {
1157                 btrfs_abort_transaction(trans, ret);
1158                 return ret;
1159         }
1160
1161         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
1162                 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
1163                 if (ret) {
1164                         btrfs_abort_transaction(trans, ret);
1165                         return ret;
1166                 }
1167         }
1168
1169         if (buf == root->node) {
1170                 WARN_ON(parent && parent != buf);
1171                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1172                     btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1173                         parent_start = buf->start;
1174
1175                 extent_buffer_get(cow);
1176                 tree_mod_log_set_root_pointer(root, cow, 1);
1177                 rcu_assign_pointer(root->node, cow);
1178
1179                 btrfs_free_tree_block(trans, root, buf, parent_start,
1180                                       last_ref);
1181                 free_extent_buffer(buf);
1182                 add_root_to_dirty_list(root);
1183         } else {
1184                 WARN_ON(trans->transid != btrfs_header_generation(parent));
1185                 tree_mod_log_insert_key(fs_info, parent, parent_slot,
1186                                         MOD_LOG_KEY_REPLACE, GFP_NOFS);
1187                 btrfs_set_node_blockptr(parent, parent_slot,
1188                                         cow->start);
1189                 btrfs_set_node_ptr_generation(parent, parent_slot,
1190                                               trans->transid);
1191                 btrfs_mark_buffer_dirty(parent);
1192                 if (last_ref) {
1193                         ret = tree_mod_log_free_eb(fs_info, buf);
1194                         if (ret) {
1195                                 btrfs_abort_transaction(trans, ret);
1196                                 return ret;
1197                         }
1198                 }
1199                 btrfs_free_tree_block(trans, root, buf, parent_start,
1200                                       last_ref);
1201         }
1202         if (unlock_orig)
1203                 btrfs_tree_unlock(buf);
1204         free_extent_buffer_stale(buf);
1205         btrfs_mark_buffer_dirty(cow);
1206         *cow_ret = cow;
1207         return 0;
1208 }
1209
1210 /*
1211  * returns the logical address of the oldest predecessor of the given root.
1212  * entries older than time_seq are ignored.
1213  */
1214 static struct tree_mod_elem *
1215 __tree_mod_log_oldest_root(struct btrfs_fs_info *fs_info,
1216                            struct extent_buffer *eb_root, u64 time_seq)
1217 {
1218         struct tree_mod_elem *tm;
1219         struct tree_mod_elem *found = NULL;
1220         u64 root_logical = eb_root->start;
1221         int looped = 0;
1222
1223         if (!time_seq)
1224                 return NULL;
1225
1226         /*
1227          * the very last operation that's logged for a root is the
1228          * replacement operation (if it is replaced at all). this has
1229          * the logical address of the *new* root, making it the very
1230          * first operation that's logged for this root.
1231          */
1232         while (1) {
1233                 tm = tree_mod_log_search_oldest(fs_info, root_logical,
1234                                                 time_seq);
1235                 if (!looped && !tm)
1236                         return NULL;
1237                 /*
1238                  * if there are no tree operation for the oldest root, we simply
1239                  * return it. this should only happen if that (old) root is at
1240                  * level 0.
1241                  */
1242                 if (!tm)
1243                         break;
1244
1245                 /*
1246                  * if there's an operation that's not a root replacement, we
1247                  * found the oldest version of our root. normally, we'll find a
1248                  * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1249                  */
1250                 if (tm->op != MOD_LOG_ROOT_REPLACE)
1251                         break;
1252
1253                 found = tm;
1254                 root_logical = tm->old_root.logical;
1255                 looped = 1;
1256         }
1257
1258         /* if there's no old root to return, return what we found instead */
1259         if (!found)
1260                 found = tm;
1261
1262         return found;
1263 }
1264
1265 /*
1266  * tm is a pointer to the first operation to rewind within eb. then, all
1267  * previous operations will be rewound (until we reach something older than
1268  * time_seq).
1269  */
1270 static void
1271 __tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1272                       u64 time_seq, struct tree_mod_elem *first_tm)
1273 {
1274         u32 n;
1275         struct rb_node *next;
1276         struct tree_mod_elem *tm = first_tm;
1277         unsigned long o_dst;
1278         unsigned long o_src;
1279         unsigned long p_size = sizeof(struct btrfs_key_ptr);
1280
1281         n = btrfs_header_nritems(eb);
1282         tree_mod_log_read_lock(fs_info);
1283         while (tm && tm->seq >= time_seq) {
1284                 /*
1285                  * all the operations are recorded with the operator used for
1286                  * the modification. as we're going backwards, we do the
1287                  * opposite of each operation here.
1288                  */
1289                 switch (tm->op) {
1290                 case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1291                         BUG_ON(tm->slot < n);
1292                         /* Fallthrough */
1293                 case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1294                 case MOD_LOG_KEY_REMOVE:
1295                         btrfs_set_node_key(eb, &tm->key, tm->slot);
1296                         btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1297                         btrfs_set_node_ptr_generation(eb, tm->slot,
1298                                                       tm->generation);
1299                         n++;
1300                         break;
1301                 case MOD_LOG_KEY_REPLACE:
1302                         BUG_ON(tm->slot >= n);
1303                         btrfs_set_node_key(eb, &tm->key, tm->slot);
1304                         btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1305                         btrfs_set_node_ptr_generation(eb, tm->slot,
1306                                                       tm->generation);
1307                         break;
1308                 case MOD_LOG_KEY_ADD:
1309                         /* if a move operation is needed it's in the log */
1310                         n--;
1311                         break;
1312                 case MOD_LOG_MOVE_KEYS:
1313                         o_dst = btrfs_node_key_ptr_offset(tm->slot);
1314                         o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1315                         memmove_extent_buffer(eb, o_dst, o_src,
1316                                               tm->move.nr_items * p_size);
1317                         break;
1318                 case MOD_LOG_ROOT_REPLACE:
1319                         /*
1320                          * this operation is special. for roots, this must be
1321                          * handled explicitly before rewinding.
1322                          * for non-roots, this operation may exist if the node
1323                          * was a root: root A -> child B; then A gets empty and
1324                          * B is promoted to the new root. in the mod log, we'll
1325                          * have a root-replace operation for B, a tree block
1326                          * that is no root. we simply ignore that operation.
1327                          */
1328                         break;
1329                 }
1330                 next = rb_next(&tm->node);
1331                 if (!next)
1332                         break;
1333                 tm = rb_entry(next, struct tree_mod_elem, node);
1334                 if (tm->logical != first_tm->logical)
1335                         break;
1336         }
1337         tree_mod_log_read_unlock(fs_info);
1338         btrfs_set_header_nritems(eb, n);
1339 }
1340
1341 /*
1342  * Called with eb read locked. If the buffer cannot be rewound, the same buffer
1343  * is returned. If rewind operations happen, a fresh buffer is returned. The
1344  * returned buffer is always read-locked. If the returned buffer is not the
1345  * input buffer, the lock on the input buffer is released and the input buffer
1346  * is freed (its refcount is decremented).
1347  */
1348 static struct extent_buffer *
1349 tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
1350                     struct extent_buffer *eb, u64 time_seq)
1351 {
1352         struct extent_buffer *eb_rewin;
1353         struct tree_mod_elem *tm;
1354
1355         if (!time_seq)
1356                 return eb;
1357
1358         if (btrfs_header_level(eb) == 0)
1359                 return eb;
1360
1361         tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1362         if (!tm)
1363                 return eb;
1364
1365         btrfs_set_path_blocking(path);
1366         btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1367
1368         if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1369                 BUG_ON(tm->slot != 0);
1370                 eb_rewin = alloc_dummy_extent_buffer(fs_info, eb->start);
1371                 if (!eb_rewin) {
1372                         btrfs_tree_read_unlock_blocking(eb);
1373                         free_extent_buffer(eb);
1374                         return NULL;
1375                 }
1376                 btrfs_set_header_bytenr(eb_rewin, eb->start);
1377                 btrfs_set_header_backref_rev(eb_rewin,
1378                                              btrfs_header_backref_rev(eb));
1379                 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1380                 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1381         } else {
1382                 eb_rewin = btrfs_clone_extent_buffer(eb);
1383                 if (!eb_rewin) {
1384                         btrfs_tree_read_unlock_blocking(eb);
1385                         free_extent_buffer(eb);
1386                         return NULL;
1387                 }
1388         }
1389
1390         btrfs_clear_path_blocking(path, NULL, BTRFS_READ_LOCK);
1391         btrfs_tree_read_unlock_blocking(eb);
1392         free_extent_buffer(eb);
1393
1394         extent_buffer_get(eb_rewin);
1395         btrfs_tree_read_lock(eb_rewin);
1396         __tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm);
1397         WARN_ON(btrfs_header_nritems(eb_rewin) >
1398                 BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1399
1400         return eb_rewin;
1401 }
1402
1403 /*
1404  * get_old_root() rewinds the state of @root's root node to the given @time_seq
1405  * value. If there are no changes, the current root->root_node is returned. If
1406  * anything changed in between, there's a fresh buffer allocated on which the
1407  * rewind operations are done. In any case, the returned buffer is read locked.
1408  * Returns NULL on error (with no locks held).
1409  */
1410 static inline struct extent_buffer *
1411 get_old_root(struct btrfs_root *root, u64 time_seq)
1412 {
1413         struct btrfs_fs_info *fs_info = root->fs_info;
1414         struct tree_mod_elem *tm;
1415         struct extent_buffer *eb = NULL;
1416         struct extent_buffer *eb_root;
1417         struct extent_buffer *old;
1418         struct tree_mod_root *old_root = NULL;
1419         u64 old_generation = 0;
1420         u64 logical;
1421
1422         eb_root = btrfs_read_lock_root_node(root);
1423         tm = __tree_mod_log_oldest_root(fs_info, eb_root, time_seq);
1424         if (!tm)
1425                 return eb_root;
1426
1427         if (tm->op == MOD_LOG_ROOT_REPLACE) {
1428                 old_root = &tm->old_root;
1429                 old_generation = tm->generation;
1430                 logical = old_root->logical;
1431         } else {
1432                 logical = eb_root->start;
1433         }
1434
1435         tm = tree_mod_log_search(fs_info, logical, time_seq);
1436         if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1437                 btrfs_tree_read_unlock(eb_root);
1438                 free_extent_buffer(eb_root);
1439                 old = read_tree_block(fs_info, logical, 0);
1440                 if (WARN_ON(IS_ERR(old) || !extent_buffer_uptodate(old))) {
1441                         if (!IS_ERR(old))
1442                                 free_extent_buffer(old);
1443                         btrfs_warn(fs_info,
1444                                    "failed to read tree block %llu from get_old_root",
1445                                    logical);
1446                 } else {
1447                         eb = btrfs_clone_extent_buffer(old);
1448                         free_extent_buffer(old);
1449                 }
1450         } else if (old_root) {
1451                 btrfs_tree_read_unlock(eb_root);
1452                 free_extent_buffer(eb_root);
1453                 eb = alloc_dummy_extent_buffer(fs_info, logical);
1454         } else {
1455                 btrfs_set_lock_blocking_rw(eb_root, BTRFS_READ_LOCK);
1456                 eb = btrfs_clone_extent_buffer(eb_root);
1457                 btrfs_tree_read_unlock_blocking(eb_root);
1458                 free_extent_buffer(eb_root);
1459         }
1460
1461         if (!eb)
1462                 return NULL;
1463         extent_buffer_get(eb);
1464         btrfs_tree_read_lock(eb);
1465         if (old_root) {
1466                 btrfs_set_header_bytenr(eb, eb->start);
1467                 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1468                 btrfs_set_header_owner(eb, btrfs_header_owner(eb_root));
1469                 btrfs_set_header_level(eb, old_root->level);
1470                 btrfs_set_header_generation(eb, old_generation);
1471         }
1472         if (tm)
1473                 __tree_mod_log_rewind(fs_info, eb, time_seq, tm);
1474         else
1475                 WARN_ON(btrfs_header_level(eb) != 0);
1476         WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1477
1478         return eb;
1479 }
1480
1481 int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
1482 {
1483         struct tree_mod_elem *tm;
1484         int level;
1485         struct extent_buffer *eb_root = btrfs_root_node(root);
1486
1487         tm = __tree_mod_log_oldest_root(root->fs_info, eb_root, time_seq);
1488         if (tm && tm->op == MOD_LOG_ROOT_REPLACE) {
1489                 level = tm->old_root.level;
1490         } else {
1491                 level = btrfs_header_level(eb_root);
1492         }
1493         free_extent_buffer(eb_root);
1494
1495         return level;
1496 }
1497
1498 static inline int should_cow_block(struct btrfs_trans_handle *trans,
1499                                    struct btrfs_root *root,
1500                                    struct extent_buffer *buf)
1501 {
1502         if (btrfs_is_testing(root->fs_info))
1503                 return 0;
1504
1505         /* ensure we can see the force_cow */
1506         smp_rmb();
1507
1508         /*
1509          * We do not need to cow a block if
1510          * 1) this block is not created or changed in this transaction;
1511          * 2) this block does not belong to TREE_RELOC tree;
1512          * 3) the root is not forced COW.
1513          *
1514          * What is forced COW:
1515          *    when we create snapshot during committing the transaction,
1516          *    after we've finished coping src root, we must COW the shared
1517          *    block to ensure the metadata consistency.
1518          */
1519         if (btrfs_header_generation(buf) == trans->transid &&
1520             !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1521             !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1522               btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1523             !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
1524                 return 0;
1525         return 1;
1526 }
1527
1528 /*
1529  * cows a single block, see __btrfs_cow_block for the real work.
1530  * This version of it has extra checks so that a block isn't COWed more than
1531  * once per transaction, as long as it hasn't been written yet
1532  */
1533 noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1534                     struct btrfs_root *root, struct extent_buffer *buf,
1535                     struct extent_buffer *parent, int parent_slot,
1536                     struct extent_buffer **cow_ret)
1537 {
1538         struct btrfs_fs_info *fs_info = root->fs_info;
1539         u64 search_start;
1540         int ret;
1541
1542         if (trans->transaction != fs_info->running_transaction)
1543                 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1544                        trans->transid,
1545                        fs_info->running_transaction->transid);
1546
1547         if (trans->transid != fs_info->generation)
1548                 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1549                        trans->transid, fs_info->generation);
1550
1551         if (!should_cow_block(trans, root, buf)) {
1552                 trans->dirty = true;
1553                 *cow_ret = buf;
1554                 return 0;
1555         }
1556
1557         search_start = buf->start & ~((u64)SZ_1G - 1);
1558
1559         if (parent)
1560                 btrfs_set_lock_blocking(parent);
1561         btrfs_set_lock_blocking(buf);
1562
1563         ret = __btrfs_cow_block(trans, root, buf, parent,
1564                                  parent_slot, cow_ret, search_start, 0);
1565
1566         trace_btrfs_cow_block(root, buf, *cow_ret);
1567
1568         return ret;
1569 }
1570
1571 /*
1572  * helper function for defrag to decide if two blocks pointed to by a
1573  * node are actually close by
1574  */
1575 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1576 {
1577         if (blocknr < other && other - (blocknr + blocksize) < 32768)
1578                 return 1;
1579         if (blocknr > other && blocknr - (other + blocksize) < 32768)
1580                 return 1;
1581         return 0;
1582 }
1583
1584 /*
1585  * compare two keys in a memcmp fashion
1586  */
1587 static int comp_keys(const struct btrfs_disk_key *disk,
1588                      const struct btrfs_key *k2)
1589 {
1590         struct btrfs_key k1;
1591
1592         btrfs_disk_key_to_cpu(&k1, disk);
1593
1594         return btrfs_comp_cpu_keys(&k1, k2);
1595 }
1596
1597 /*
1598  * same as comp_keys only with two btrfs_key's
1599  */
1600 int btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
1601 {
1602         if (k1->objectid > k2->objectid)
1603                 return 1;
1604         if (k1->objectid < k2->objectid)
1605                 return -1;
1606         if (k1->type > k2->type)
1607                 return 1;
1608         if (k1->type < k2->type)
1609                 return -1;
1610         if (k1->offset > k2->offset)
1611                 return 1;
1612         if (k1->offset < k2->offset)
1613                 return -1;
1614         return 0;
1615 }
1616
1617 /*
1618  * this is used by the defrag code to go through all the
1619  * leaves pointed to by a node and reallocate them so that
1620  * disk order is close to key order
1621  */
1622 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1623                        struct btrfs_root *root, struct extent_buffer *parent,
1624                        int start_slot, u64 *last_ret,
1625                        struct btrfs_key *progress)
1626 {
1627         struct btrfs_fs_info *fs_info = root->fs_info;
1628         struct extent_buffer *cur;
1629         u64 blocknr;
1630         u64 gen;
1631         u64 search_start = *last_ret;
1632         u64 last_block = 0;
1633         u64 other;
1634         u32 parent_nritems;
1635         int end_slot;
1636         int i;
1637         int err = 0;
1638         int parent_level;
1639         int uptodate;
1640         u32 blocksize;
1641         int progress_passed = 0;
1642         struct btrfs_disk_key disk_key;
1643
1644         parent_level = btrfs_header_level(parent);
1645
1646         WARN_ON(trans->transaction != fs_info->running_transaction);
1647         WARN_ON(trans->transid != fs_info->generation);
1648
1649         parent_nritems = btrfs_header_nritems(parent);
1650         blocksize = fs_info->nodesize;
1651         end_slot = parent_nritems - 1;
1652
1653         if (parent_nritems <= 1)
1654                 return 0;
1655
1656         btrfs_set_lock_blocking(parent);
1657
1658         for (i = start_slot; i <= end_slot; i++) {
1659                 int close = 1;
1660
1661                 btrfs_node_key(parent, &disk_key, i);
1662                 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1663                         continue;
1664
1665                 progress_passed = 1;
1666                 blocknr = btrfs_node_blockptr(parent, i);
1667                 gen = btrfs_node_ptr_generation(parent, i);
1668                 if (last_block == 0)
1669                         last_block = blocknr;
1670
1671                 if (i > 0) {
1672                         other = btrfs_node_blockptr(parent, i - 1);
1673                         close = close_blocks(blocknr, other, blocksize);
1674                 }
1675                 if (!close && i < end_slot) {
1676                         other = btrfs_node_blockptr(parent, i + 1);
1677                         close = close_blocks(blocknr, other, blocksize);
1678                 }
1679                 if (close) {
1680                         last_block = blocknr;
1681                         continue;
1682                 }
1683
1684                 cur = find_extent_buffer(fs_info, blocknr);
1685                 if (cur)
1686                         uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1687                 else
1688                         uptodate = 0;
1689                 if (!cur || !uptodate) {
1690                         if (!cur) {
1691                                 cur = read_tree_block(fs_info, blocknr, gen);
1692                                 if (IS_ERR(cur)) {
1693                                         return PTR_ERR(cur);
1694                                 } else if (!extent_buffer_uptodate(cur)) {
1695                                         free_extent_buffer(cur);
1696                                         return -EIO;
1697                                 }
1698                         } else if (!uptodate) {
1699                                 err = btrfs_read_buffer(cur, gen);
1700                                 if (err) {
1701                                         free_extent_buffer(cur);
1702                                         return err;
1703                                 }
1704                         }
1705                 }
1706                 if (search_start == 0)
1707                         search_start = last_block;
1708
1709                 btrfs_tree_lock(cur);
1710                 btrfs_set_lock_blocking(cur);
1711                 err = __btrfs_cow_block(trans, root, cur, parent, i,
1712                                         &cur, search_start,
1713                                         min(16 * blocksize,
1714                                             (end_slot - i) * blocksize));
1715                 if (err) {
1716                         btrfs_tree_unlock(cur);
1717                         free_extent_buffer(cur);
1718                         break;
1719                 }
1720                 search_start = cur->start;
1721                 last_block = cur->start;
1722                 *last_ret = search_start;
1723                 btrfs_tree_unlock(cur);
1724                 free_extent_buffer(cur);
1725         }
1726         return err;
1727 }
1728
1729 /*
1730  * search for key in the extent_buffer.  The items start at offset p,
1731  * and they are item_size apart.  There are 'max' items in p.
1732  *
1733  * the slot in the array is returned via slot, and it points to
1734  * the place where you would insert key if it is not found in
1735  * the array.
1736  *
1737  * slot may point to max if the key is bigger than all of the keys
1738  */
1739 static noinline int generic_bin_search(struct extent_buffer *eb,
1740                                        unsigned long p, int item_size,
1741                                        const struct btrfs_key *key,
1742                                        int max, int *slot)
1743 {
1744         int low = 0;
1745         int high = max;
1746         int mid;
1747         int ret;
1748         struct btrfs_disk_key *tmp = NULL;
1749         struct btrfs_disk_key unaligned;
1750         unsigned long offset;
1751         char *kaddr = NULL;
1752         unsigned long map_start = 0;
1753         unsigned long map_len = 0;
1754         int err;
1755
1756         if (low > high) {
1757                 btrfs_err(eb->fs_info,
1758                  "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
1759                           __func__, low, high, eb->start,
1760                           btrfs_header_owner(eb), btrfs_header_level(eb));
1761                 return -EINVAL;
1762         }
1763
1764         while (low < high) {
1765                 mid = (low + high) / 2;
1766                 offset = p + mid * item_size;
1767
1768                 if (!kaddr || offset < map_start ||
1769                     (offset + sizeof(struct btrfs_disk_key)) >
1770                     map_start + map_len) {
1771
1772                         err = map_private_extent_buffer(eb, offset,
1773                                                 sizeof(struct btrfs_disk_key),
1774                                                 &kaddr, &map_start, &map_len);
1775
1776                         if (!err) {
1777                                 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1778                                                         map_start);
1779                         } else if (err == 1) {
1780                                 read_extent_buffer(eb, &unaligned,
1781                                                    offset, sizeof(unaligned));
1782                                 tmp = &unaligned;
1783                         } else {
1784                                 return err;
1785                         }
1786
1787                 } else {
1788                         tmp = (struct btrfs_disk_key *)(kaddr + offset -
1789                                                         map_start);
1790                 }
1791                 ret = comp_keys(tmp, key);
1792
1793                 if (ret < 0)
1794                         low = mid + 1;
1795                 else if (ret > 0)
1796                         high = mid;
1797                 else {
1798                         *slot = mid;
1799                         return 0;
1800                 }
1801         }
1802         *slot = low;
1803         return 1;
1804 }
1805
1806 /*
1807  * simple bin_search frontend that does the right thing for
1808  * leaves vs nodes
1809  */
1810 static int bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
1811                       int level, int *slot)
1812 {
1813         if (level == 0)
1814                 return generic_bin_search(eb,
1815                                           offsetof(struct btrfs_leaf, items),
1816                                           sizeof(struct btrfs_item),
1817                                           key, btrfs_header_nritems(eb),
1818                                           slot);
1819         else
1820                 return generic_bin_search(eb,
1821                                           offsetof(struct btrfs_node, ptrs),
1822                                           sizeof(struct btrfs_key_ptr),
1823                                           key, btrfs_header_nritems(eb),
1824                                           slot);
1825 }
1826
1827 int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
1828                      int level, int *slot)
1829 {
1830         return bin_search(eb, key, level, slot);
1831 }
1832
1833 static void root_add_used(struct btrfs_root *root, u32 size)
1834 {
1835         spin_lock(&root->accounting_lock);
1836         btrfs_set_root_used(&root->root_item,
1837                             btrfs_root_used(&root->root_item) + size);
1838         spin_unlock(&root->accounting_lock);
1839 }
1840
1841 static void root_sub_used(struct btrfs_root *root, u32 size)
1842 {
1843         spin_lock(&root->accounting_lock);
1844         btrfs_set_root_used(&root->root_item,
1845                             btrfs_root_used(&root->root_item) - size);
1846         spin_unlock(&root->accounting_lock);
1847 }
1848
1849 /* given a node and slot number, this reads the blocks it points to.  The
1850  * extent buffer is returned with a reference taken (but unlocked).
1851  */
1852 static noinline struct extent_buffer *
1853 read_node_slot(struct btrfs_fs_info *fs_info, struct extent_buffer *parent,
1854                int slot)
1855 {
1856         int level = btrfs_header_level(parent);
1857         struct extent_buffer *eb;
1858
1859         if (slot < 0 || slot >= btrfs_header_nritems(parent))
1860                 return ERR_PTR(-ENOENT);
1861
1862         BUG_ON(level == 0);
1863
1864         eb = read_tree_block(fs_info, btrfs_node_blockptr(parent, slot),
1865                              btrfs_node_ptr_generation(parent, slot));
1866         if (!IS_ERR(eb) && !extent_buffer_uptodate(eb)) {
1867                 free_extent_buffer(eb);
1868                 eb = ERR_PTR(-EIO);
1869         }
1870
1871         return eb;
1872 }
1873
1874 /*
1875  * node level balancing, used to make sure nodes are in proper order for
1876  * item deletion.  We balance from the top down, so we have to make sure
1877  * that a deletion won't leave an node completely empty later on.
1878  */
1879 static noinline int balance_level(struct btrfs_trans_handle *trans,
1880                          struct btrfs_root *root,
1881                          struct btrfs_path *path, int level)
1882 {
1883         struct btrfs_fs_info *fs_info = root->fs_info;
1884         struct extent_buffer *right = NULL;
1885         struct extent_buffer *mid;
1886         struct extent_buffer *left = NULL;
1887         struct extent_buffer *parent = NULL;
1888         int ret = 0;
1889         int wret;
1890         int pslot;
1891         int orig_slot = path->slots[level];
1892         u64 orig_ptr;
1893
1894         if (level == 0)
1895                 return 0;
1896
1897         mid = path->nodes[level];
1898
1899         WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1900                 path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1901         WARN_ON(btrfs_header_generation(mid) != trans->transid);
1902
1903         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1904
1905         if (level < BTRFS_MAX_LEVEL - 1) {
1906                 parent = path->nodes[level + 1];
1907                 pslot = path->slots[level + 1];
1908         }
1909
1910         /*
1911          * deal with the case where there is only one pointer in the root
1912          * by promoting the node below to a root
1913          */
1914         if (!parent) {
1915                 struct extent_buffer *child;
1916
1917                 if (btrfs_header_nritems(mid) != 1)
1918                         return 0;
1919
1920                 /* promote the child to a root */
1921                 child = read_node_slot(fs_info, mid, 0);
1922                 if (IS_ERR(child)) {
1923                         ret = PTR_ERR(child);
1924                         btrfs_handle_fs_error(fs_info, ret, NULL);
1925                         goto enospc;
1926                 }
1927
1928                 btrfs_tree_lock(child);
1929                 btrfs_set_lock_blocking(child);
1930                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1931                 if (ret) {
1932                         btrfs_tree_unlock(child);
1933                         free_extent_buffer(child);
1934                         goto enospc;
1935                 }
1936
1937                 tree_mod_log_set_root_pointer(root, child, 1);
1938                 rcu_assign_pointer(root->node, child);
1939
1940                 add_root_to_dirty_list(root);
1941                 btrfs_tree_unlock(child);
1942
1943                 path->locks[level] = 0;
1944                 path->nodes[level] = NULL;
1945                 clean_tree_block(fs_info, mid);
1946                 btrfs_tree_unlock(mid);
1947                 /* once for the path */
1948                 free_extent_buffer(mid);
1949
1950                 root_sub_used(root, mid->len);
1951                 btrfs_free_tree_block(trans, root, mid, 0, 1);
1952                 /* once for the root ptr */
1953                 free_extent_buffer_stale(mid);
1954                 return 0;
1955         }
1956         if (btrfs_header_nritems(mid) >
1957             BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
1958                 return 0;
1959
1960         left = read_node_slot(fs_info, parent, pslot - 1);
1961         if (IS_ERR(left))
1962                 left = NULL;
1963
1964         if (left) {
1965                 btrfs_tree_lock(left);
1966                 btrfs_set_lock_blocking(left);
1967                 wret = btrfs_cow_block(trans, root, left,
1968                                        parent, pslot - 1, &left);
1969                 if (wret) {
1970                         ret = wret;
1971                         goto enospc;
1972                 }
1973         }
1974
1975         right = read_node_slot(fs_info, parent, pslot + 1);
1976         if (IS_ERR(right))
1977                 right = NULL;
1978
1979         if (right) {
1980                 btrfs_tree_lock(right);
1981                 btrfs_set_lock_blocking(right);
1982                 wret = btrfs_cow_block(trans, root, right,
1983                                        parent, pslot + 1, &right);
1984                 if (wret) {
1985                         ret = wret;
1986                         goto enospc;
1987                 }
1988         }
1989
1990         /* first, try to make some room in the middle buffer */
1991         if (left) {
1992                 orig_slot += btrfs_header_nritems(left);
1993                 wret = push_node_left(trans, fs_info, left, mid, 1);
1994                 if (wret < 0)
1995                         ret = wret;
1996         }
1997
1998         /*
1999          * then try to empty the right most buffer into the middle
2000          */
2001         if (right) {
2002                 wret = push_node_left(trans, fs_info, mid, right, 1);
2003                 if (wret < 0 && wret != -ENOSPC)
2004                         ret = wret;
2005                 if (btrfs_header_nritems(right) == 0) {
2006                         clean_tree_block(fs_info, right);
2007                         btrfs_tree_unlock(right);
2008                         del_ptr(root, path, level + 1, pslot + 1);
2009                         root_sub_used(root, right->len);
2010                         btrfs_free_tree_block(trans, root, right, 0, 1);
2011                         free_extent_buffer_stale(right);
2012                         right = NULL;
2013                 } else {
2014                         struct btrfs_disk_key right_key;
2015                         btrfs_node_key(right, &right_key, 0);
2016                         tree_mod_log_set_node_key(fs_info, parent,
2017                                                   pslot + 1, 0);
2018                         btrfs_set_node_key(parent, &right_key, pslot + 1);
2019                         btrfs_mark_buffer_dirty(parent);
2020                 }
2021         }
2022         if (btrfs_header_nritems(mid) == 1) {
2023                 /*
2024                  * we're not allowed to leave a node with one item in the
2025                  * tree during a delete.  A deletion from lower in the tree
2026                  * could try to delete the only pointer in this node.
2027                  * So, pull some keys from the left.
2028                  * There has to be a left pointer at this point because
2029                  * otherwise we would have pulled some pointers from the
2030                  * right
2031                  */
2032                 if (!left) {
2033                         ret = -EROFS;
2034                         btrfs_handle_fs_error(fs_info, ret, NULL);
2035                         goto enospc;
2036                 }
2037                 wret = balance_node_right(trans, fs_info, mid, left);
2038                 if (wret < 0) {
2039                         ret = wret;
2040                         goto enospc;
2041                 }
2042                 if (wret == 1) {
2043                         wret = push_node_left(trans, fs_info, left, mid, 1);
2044                         if (wret < 0)
2045                                 ret = wret;
2046                 }
2047                 BUG_ON(wret == 1);
2048         }
2049         if (btrfs_header_nritems(mid) == 0) {
2050                 clean_tree_block(fs_info, mid);
2051                 btrfs_tree_unlock(mid);
2052                 del_ptr(root, path, level + 1, pslot);
2053                 root_sub_used(root, mid->len);
2054                 btrfs_free_tree_block(trans, root, mid, 0, 1);
2055                 free_extent_buffer_stale(mid);
2056                 mid = NULL;
2057         } else {
2058                 /* update the parent key to reflect our changes */
2059                 struct btrfs_disk_key mid_key;
2060                 btrfs_node_key(mid, &mid_key, 0);
2061                 tree_mod_log_set_node_key(fs_info, parent, pslot, 0);
2062                 btrfs_set_node_key(parent, &mid_key, pslot);
2063                 btrfs_mark_buffer_dirty(parent);
2064         }
2065
2066         /* update the path */
2067         if (left) {
2068                 if (btrfs_header_nritems(left) > orig_slot) {
2069                         extent_buffer_get(left);
2070                         /* left was locked after cow */
2071                         path->nodes[level] = left;
2072                         path->slots[level + 1] -= 1;
2073                         path->slots[level] = orig_slot;
2074                         if (mid) {
2075                                 btrfs_tree_unlock(mid);
2076                                 free_extent_buffer(mid);
2077                         }
2078                 } else {
2079                         orig_slot -= btrfs_header_nritems(left);
2080                         path->slots[level] = orig_slot;
2081                 }
2082         }
2083         /* double check we haven't messed things up */
2084         if (orig_ptr !=
2085             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
2086                 BUG();
2087 enospc:
2088         if (right) {
2089                 btrfs_tree_unlock(right);
2090                 free_extent_buffer(right);
2091         }
2092         if (left) {
2093                 if (path->nodes[level] != left)
2094                         btrfs_tree_unlock(left);
2095                 free_extent_buffer(left);
2096         }
2097         return ret;
2098 }
2099
2100 /* Node balancing for insertion.  Here we only split or push nodes around
2101  * when they are completely full.  This is also done top down, so we
2102  * have to be pessimistic.
2103  */
2104 static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
2105                                           struct btrfs_root *root,
2106                                           struct btrfs_path *path, int level)
2107 {
2108         struct btrfs_fs_info *fs_info = root->fs_info;
2109         struct extent_buffer *right = NULL;
2110         struct extent_buffer *mid;
2111         struct extent_buffer *left = NULL;
2112         struct extent_buffer *parent = NULL;
2113         int ret = 0;
2114         int wret;
2115         int pslot;
2116         int orig_slot = path->slots[level];
2117
2118         if (level == 0)
2119                 return 1;
2120
2121         mid = path->nodes[level];
2122         WARN_ON(btrfs_header_generation(mid) != trans->transid);
2123
2124         if (level < BTRFS_MAX_LEVEL - 1) {
2125                 parent = path->nodes[level + 1];
2126                 pslot = path->slots[level + 1];
2127         }
2128
2129         if (!parent)
2130                 return 1;
2131
2132         left = read_node_slot(fs_info, parent, pslot - 1);
2133         if (IS_ERR(left))
2134                 left = NULL;
2135
2136         /* first, try to make some room in the middle buffer */
2137         if (left) {
2138                 u32 left_nr;
2139
2140                 btrfs_tree_lock(left);
2141                 btrfs_set_lock_blocking(left);
2142
2143                 left_nr = btrfs_header_nritems(left);
2144                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2145                         wret = 1;
2146                 } else {
2147                         ret = btrfs_cow_block(trans, root, left, parent,
2148                                               pslot - 1, &left);
2149                         if (ret)
2150                                 wret = 1;
2151                         else {
2152                                 wret = push_node_left(trans, fs_info,
2153                                                       left, mid, 0);
2154                         }
2155                 }
2156                 if (wret < 0)
2157                         ret = wret;
2158                 if (wret == 0) {
2159                         struct btrfs_disk_key disk_key;
2160                         orig_slot += left_nr;
2161                         btrfs_node_key(mid, &disk_key, 0);
2162                         tree_mod_log_set_node_key(fs_info, parent, pslot, 0);
2163                         btrfs_set_node_key(parent, &disk_key, pslot);
2164                         btrfs_mark_buffer_dirty(parent);
2165                         if (btrfs_header_nritems(left) > orig_slot) {
2166                                 path->nodes[level] = left;
2167                                 path->slots[level + 1] -= 1;
2168                                 path->slots[level] = orig_slot;
2169                                 btrfs_tree_unlock(mid);
2170                                 free_extent_buffer(mid);
2171                         } else {
2172                                 orig_slot -=
2173                                         btrfs_header_nritems(left);
2174                                 path->slots[level] = orig_slot;
2175                                 btrfs_tree_unlock(left);
2176                                 free_extent_buffer(left);
2177                         }
2178                         return 0;
2179                 }
2180                 btrfs_tree_unlock(left);
2181                 free_extent_buffer(left);
2182         }
2183         right = read_node_slot(fs_info, parent, pslot + 1);
2184         if (IS_ERR(right))
2185                 right = NULL;
2186
2187         /*
2188          * then try to empty the right most buffer into the middle
2189          */
2190         if (right) {
2191                 u32 right_nr;
2192
2193                 btrfs_tree_lock(right);
2194                 btrfs_set_lock_blocking(right);
2195
2196                 right_nr = btrfs_header_nritems(right);
2197                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2198                         wret = 1;
2199                 } else {
2200                         ret = btrfs_cow_block(trans, root, right,
2201                                               parent, pslot + 1,
2202                                               &right);
2203                         if (ret)
2204                                 wret = 1;
2205                         else {
2206                                 wret = balance_node_right(trans, fs_info,
2207                                                           right, mid);
2208                         }
2209                 }
2210                 if (wret < 0)
2211                         ret = wret;
2212                 if (wret == 0) {
2213                         struct btrfs_disk_key disk_key;
2214
2215                         btrfs_node_key(right, &disk_key, 0);
2216                         tree_mod_log_set_node_key(fs_info, parent,
2217                                                   pslot + 1, 0);
2218                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
2219                         btrfs_mark_buffer_dirty(parent);
2220
2221                         if (btrfs_header_nritems(mid) <= orig_slot) {
2222                                 path->nodes[level] = right;
2223                                 path->slots[level + 1] += 1;
2224                                 path->slots[level] = orig_slot -
2225                                         btrfs_header_nritems(mid);
2226                                 btrfs_tree_unlock(mid);
2227                                 free_extent_buffer(mid);
2228                         } else {
2229                                 btrfs_tree_unlock(right);
2230                                 free_extent_buffer(right);
2231                         }
2232                         return 0;
2233                 }
2234                 btrfs_tree_unlock(right);
2235                 free_extent_buffer(right);
2236         }
2237         return 1;
2238 }
2239
2240 /*
2241  * readahead one full node of leaves, finding things that are close
2242  * to the block in 'slot', and triggering ra on them.
2243  */
2244 static void reada_for_search(struct btrfs_fs_info *fs_info,
2245                              struct btrfs_path *path,
2246                              int level, int slot, u64 objectid)
2247 {
2248         struct extent_buffer *node;
2249         struct btrfs_disk_key disk_key;
2250         u32 nritems;
2251         u64 search;
2252         u64 target;
2253         u64 nread = 0;
2254         struct extent_buffer *eb;
2255         u32 nr;
2256         u32 blocksize;
2257         u32 nscan = 0;
2258
2259         if (level != 1)
2260                 return;
2261
2262         if (!path->nodes[level])
2263                 return;
2264
2265         node = path->nodes[level];
2266
2267         search = btrfs_node_blockptr(node, slot);
2268         blocksize = fs_info->nodesize;
2269         eb = find_extent_buffer(fs_info, search);
2270         if (eb) {
2271                 free_extent_buffer(eb);
2272                 return;
2273         }
2274
2275         target = search;
2276
2277         nritems = btrfs_header_nritems(node);
2278         nr = slot;
2279
2280         while (1) {
2281                 if (path->reada == READA_BACK) {
2282                         if (nr == 0)
2283                                 break;
2284                         nr--;
2285                 } else if (path->reada == READA_FORWARD) {
2286                         nr++;
2287                         if (nr >= nritems)
2288                                 break;
2289                 }
2290                 if (path->reada == READA_BACK && objectid) {
2291                         btrfs_node_key(node, &disk_key, nr);
2292                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
2293                                 break;
2294                 }
2295                 search = btrfs_node_blockptr(node, nr);
2296                 if ((search <= target && target - search <= 65536) ||
2297                     (search > target && search - target <= 65536)) {
2298                         readahead_tree_block(fs_info, search);
2299                         nread += blocksize;
2300                 }
2301                 nscan++;
2302                 if ((nread > 65536 || nscan > 32))
2303                         break;
2304         }
2305 }
2306
2307 static noinline void reada_for_balance(struct btrfs_fs_info *fs_info,
2308                                        struct btrfs_path *path, int level)
2309 {
2310         int slot;
2311         int nritems;
2312         struct extent_buffer *parent;
2313         struct extent_buffer *eb;
2314         u64 gen;
2315         u64 block1 = 0;
2316         u64 block2 = 0;
2317
2318         parent = path->nodes[level + 1];
2319         if (!parent)
2320                 return;
2321
2322         nritems = btrfs_header_nritems(parent);
2323         slot = path->slots[level + 1];
2324
2325         if (slot > 0) {
2326                 block1 = btrfs_node_blockptr(parent, slot - 1);
2327                 gen = btrfs_node_ptr_generation(parent, slot - 1);
2328                 eb = find_extent_buffer(fs_info, block1);
2329                 /*
2330                  * if we get -eagain from btrfs_buffer_uptodate, we
2331                  * don't want to return eagain here.  That will loop
2332                  * forever
2333                  */
2334                 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2335                         block1 = 0;
2336                 free_extent_buffer(eb);
2337         }
2338         if (slot + 1 < nritems) {
2339                 block2 = btrfs_node_blockptr(parent, slot + 1);
2340                 gen = btrfs_node_ptr_generation(parent, slot + 1);
2341                 eb = find_extent_buffer(fs_info, block2);
2342                 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2343                         block2 = 0;
2344                 free_extent_buffer(eb);
2345         }
2346
2347         if (block1)
2348                 readahead_tree_block(fs_info, block1);
2349         if (block2)
2350                 readahead_tree_block(fs_info, block2);
2351 }
2352
2353
2354 /*
2355  * when we walk down the tree, it is usually safe to unlock the higher layers
2356  * in the tree.  The exceptions are when our path goes through slot 0, because
2357  * operations on the tree might require changing key pointers higher up in the
2358  * tree.
2359  *
2360  * callers might also have set path->keep_locks, which tells this code to keep
2361  * the lock if the path points to the last slot in the block.  This is part of
2362  * walking through the tree, and selecting the next slot in the higher block.
2363  *
2364  * lowest_unlock sets the lowest level in the tree we're allowed to unlock.  so
2365  * if lowest_unlock is 1, level 0 won't be unlocked
2366  */
2367 static noinline void unlock_up(struct btrfs_path *path, int level,
2368                                int lowest_unlock, int min_write_lock_level,
2369                                int *write_lock_level)
2370 {
2371         int i;
2372         int skip_level = level;
2373         int no_skips = 0;
2374         struct extent_buffer *t;
2375
2376         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2377                 if (!path->nodes[i])
2378                         break;
2379                 if (!path->locks[i])
2380                         break;
2381                 if (!no_skips && path->slots[i] == 0) {
2382                         skip_level = i + 1;
2383                         continue;
2384                 }
2385                 if (!no_skips && path->keep_locks) {
2386                         u32 nritems;
2387                         t = path->nodes[i];
2388                         nritems = btrfs_header_nritems(t);
2389                         if (nritems < 1 || path->slots[i] >= nritems - 1) {
2390                                 skip_level = i + 1;
2391                                 continue;
2392                         }
2393                 }
2394                 if (skip_level < i && i >= lowest_unlock)
2395                         no_skips = 1;
2396
2397                 t = path->nodes[i];
2398                 if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
2399                         btrfs_tree_unlock_rw(t, path->locks[i]);
2400                         path->locks[i] = 0;
2401                         if (write_lock_level &&
2402                             i > min_write_lock_level &&
2403                             i <= *write_lock_level) {
2404                                 *write_lock_level = i - 1;
2405                         }
2406                 }
2407         }
2408 }
2409
2410 /*
2411  * This releases any locks held in the path starting at level and
2412  * going all the way up to the root.
2413  *
2414  * btrfs_search_slot will keep the lock held on higher nodes in a few
2415  * corner cases, such as COW of the block at slot zero in the node.  This
2416  * ignores those rules, and it should only be called when there are no
2417  * more updates to be done higher up in the tree.
2418  */
2419 noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
2420 {
2421         int i;
2422
2423         if (path->keep_locks)
2424                 return;
2425
2426         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2427                 if (!path->nodes[i])
2428                         continue;
2429                 if (!path->locks[i])
2430                         continue;
2431                 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
2432                 path->locks[i] = 0;
2433         }
2434 }
2435
2436 /*
2437  * helper function for btrfs_search_slot.  The goal is to find a block
2438  * in cache without setting the path to blocking.  If we find the block
2439  * we return zero and the path is unchanged.
2440  *
2441  * If we can't find the block, we set the path blocking and do some
2442  * reada.  -EAGAIN is returned and the search must be repeated.
2443  */
2444 static int
2445 read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
2446                       struct extent_buffer **eb_ret, int level, int slot,
2447                       const struct btrfs_key *key)
2448 {
2449         struct btrfs_fs_info *fs_info = root->fs_info;
2450         u64 blocknr;
2451         u64 gen;
2452         struct extent_buffer *b = *eb_ret;
2453         struct extent_buffer *tmp;
2454         int ret;
2455
2456         blocknr = btrfs_node_blockptr(b, slot);
2457         gen = btrfs_node_ptr_generation(b, slot);
2458
2459         tmp = find_extent_buffer(fs_info, blocknr);
2460         if (tmp) {
2461                 /* first we do an atomic uptodate check */
2462                 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2463                         *eb_ret = tmp;
2464                         return 0;
2465                 }
2466
2467                 /* the pages were up to date, but we failed
2468                  * the generation number check.  Do a full
2469                  * read for the generation number that is correct.
2470                  * We must do this without dropping locks so
2471                  * we can trust our generation number
2472                  */
2473                 btrfs_set_path_blocking(p);
2474
2475                 /* now we're allowed to do a blocking uptodate check */
2476                 ret = btrfs_read_buffer(tmp, gen);
2477                 if (!ret) {
2478                         *eb_ret = tmp;
2479                         return 0;
2480                 }
2481                 free_extent_buffer(tmp);
2482                 btrfs_release_path(p);
2483                 return -EIO;
2484         }
2485
2486         /*
2487          * reduce lock contention at high levels
2488          * of the btree by dropping locks before
2489          * we read.  Don't release the lock on the current
2490          * level because we need to walk this node to figure
2491          * out which blocks to read.
2492          */
2493         btrfs_unlock_up_safe(p, level + 1);
2494         btrfs_set_path_blocking(p);
2495
2496         free_extent_buffer(tmp);
2497         if (p->reada != READA_NONE)
2498                 reada_for_search(fs_info, p, level, slot, key->objectid);
2499
2500         ret = -EAGAIN;
2501         tmp = read_tree_block(fs_info, blocknr, gen);
2502         if (!IS_ERR(tmp)) {
2503                 /*
2504                  * If the read above didn't mark this buffer up to date,
2505                  * it will never end up being up to date.  Set ret to EIO now
2506                  * and give up so that our caller doesn't loop forever
2507                  * on our EAGAINs.
2508                  */
2509                 if (!btrfs_buffer_uptodate(tmp, 0, 0))
2510                         ret = -EIO;
2511                 free_extent_buffer(tmp);
2512         } else {
2513                 ret = PTR_ERR(tmp);
2514         }
2515
2516         btrfs_release_path(p);
2517         return ret;
2518 }
2519
2520 /*
2521  * helper function for btrfs_search_slot.  This does all of the checks
2522  * for node-level blocks and does any balancing required based on
2523  * the ins_len.
2524  *
2525  * If no extra work was required, zero is returned.  If we had to
2526  * drop the path, -EAGAIN is returned and btrfs_search_slot must
2527  * start over
2528  */
2529 static int
2530 setup_nodes_for_search(struct btrfs_trans_handle *trans,
2531                        struct btrfs_root *root, struct btrfs_path *p,
2532                        struct extent_buffer *b, int level, int ins_len,
2533                        int *write_lock_level)
2534 {
2535         struct btrfs_fs_info *fs_info = root->fs_info;
2536         int ret;
2537
2538         if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2539             BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
2540                 int sret;
2541
2542                 if (*write_lock_level < level + 1) {
2543                         *write_lock_level = level + 1;
2544                         btrfs_release_path(p);
2545                         goto again;
2546                 }
2547
2548                 btrfs_set_path_blocking(p);
2549                 reada_for_balance(fs_info, p, level);
2550                 sret = split_node(trans, root, p, level);
2551                 btrfs_clear_path_blocking(p, NULL, 0);
2552
2553                 BUG_ON(sret > 0);
2554                 if (sret) {
2555                         ret = sret;
2556                         goto done;
2557                 }
2558                 b = p->nodes[level];
2559         } else if (ins_len < 0 && btrfs_header_nritems(b) <
2560                    BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
2561                 int sret;
2562
2563                 if (*write_lock_level < level + 1) {
2564                         *write_lock_level = level + 1;
2565                         btrfs_release_path(p);
2566                         goto again;
2567                 }
2568
2569                 btrfs_set_path_blocking(p);
2570                 reada_for_balance(fs_info, p, level);
2571                 sret = balance_level(trans, root, p, level);
2572                 btrfs_clear_path_blocking(p, NULL, 0);
2573
2574                 if (sret) {
2575                         ret = sret;
2576                         goto done;
2577                 }
2578                 b = p->nodes[level];
2579                 if (!b) {
2580                         btrfs_release_path(p);
2581                         goto again;
2582                 }
2583                 BUG_ON(btrfs_header_nritems(b) == 1);
2584         }
2585         return 0;
2586
2587 again:
2588         ret = -EAGAIN;
2589 done:
2590         return ret;
2591 }
2592
2593 static void key_search_validate(struct extent_buffer *b,
2594                                 const struct btrfs_key *key,
2595                                 int level)
2596 {
2597 #ifdef CONFIG_BTRFS_ASSERT
2598         struct btrfs_disk_key disk_key;
2599
2600         btrfs_cpu_key_to_disk(&disk_key, key);
2601
2602         if (level == 0)
2603                 ASSERT(!memcmp_extent_buffer(b, &disk_key,
2604                     offsetof(struct btrfs_leaf, items[0].key),
2605                     sizeof(disk_key)));
2606         else
2607                 ASSERT(!memcmp_extent_buffer(b, &disk_key,
2608                     offsetof(struct btrfs_node, ptrs[0].key),
2609                     sizeof(disk_key)));
2610 #endif
2611 }
2612
2613 static int key_search(struct extent_buffer *b, const struct btrfs_key *key,
2614                       int level, int *prev_cmp, int *slot)
2615 {
2616         if (*prev_cmp != 0) {
2617                 *prev_cmp = bin_search(b, key, level, slot);
2618                 return *prev_cmp;
2619         }
2620
2621         key_search_validate(b, key, level);
2622         *slot = 0;
2623
2624         return 0;
2625 }
2626
2627 int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
2628                 u64 iobjectid, u64 ioff, u8 key_type,
2629                 struct btrfs_key *found_key)
2630 {
2631         int ret;
2632         struct btrfs_key key;
2633         struct extent_buffer *eb;
2634
2635         ASSERT(path);
2636         ASSERT(found_key);
2637
2638         key.type = key_type;
2639         key.objectid = iobjectid;
2640         key.offset = ioff;
2641
2642         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
2643         if (ret < 0)
2644                 return ret;
2645
2646         eb = path->nodes[0];
2647         if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
2648                 ret = btrfs_next_leaf(fs_root, path);
2649                 if (ret)
2650                         return ret;
2651                 eb = path->nodes[0];
2652         }
2653
2654         btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
2655         if (found_key->type != key.type ||
2656                         found_key->objectid != key.objectid)
2657                 return 1;
2658
2659         return 0;
2660 }
2661
2662 /*
2663  * look for key in the tree.  path is filled in with nodes along the way
2664  * if key is found, we return zero and you can find the item in the leaf
2665  * level of the path (level 0)
2666  *
2667  * If the key isn't found, the path points to the slot where it should
2668  * be inserted, and 1 is returned.  If there are other errors during the
2669  * search a negative error number is returned.
2670  *
2671  * if ins_len > 0, nodes and leaves will be split as we walk down the
2672  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
2673  * possible)
2674  */
2675 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2676                       const struct btrfs_key *key, struct btrfs_path *p,
2677                       int ins_len, int cow)
2678 {
2679         struct btrfs_fs_info *fs_info = root->fs_info;
2680         struct extent_buffer *b;
2681         int slot;
2682         int ret;
2683         int err;
2684         int level;
2685         int lowest_unlock = 1;
2686         int root_lock;
2687         /* everything at write_lock_level or lower must be write locked */
2688         int write_lock_level = 0;
2689         u8 lowest_level = 0;
2690         int min_write_lock_level;
2691         int prev_cmp;
2692
2693         lowest_level = p->lowest_level;
2694         WARN_ON(lowest_level && ins_len > 0);
2695         WARN_ON(p->nodes[0] != NULL);
2696         BUG_ON(!cow && ins_len);
2697
2698         if (ins_len < 0) {
2699                 lowest_unlock = 2;
2700
2701                 /* when we are removing items, we might have to go up to level
2702                  * two as we update tree pointers  Make sure we keep write
2703                  * for those levels as well
2704                  */
2705                 write_lock_level = 2;
2706         } else if (ins_len > 0) {
2707                 /*
2708                  * for inserting items, make sure we have a write lock on
2709                  * level 1 so we can update keys
2710                  */
2711                 write_lock_level = 1;
2712         }
2713
2714         if (!cow)
2715                 write_lock_level = -1;
2716
2717         if (cow && (p->keep_locks || p->lowest_level))
2718                 write_lock_level = BTRFS_MAX_LEVEL;
2719
2720         min_write_lock_level = write_lock_level;
2721
2722 again:
2723         prev_cmp = -1;
2724         /*
2725          * we try very hard to do read locks on the root
2726          */
2727         root_lock = BTRFS_READ_LOCK;
2728         level = 0;
2729         if (p->search_commit_root) {
2730                 /*
2731                  * the commit roots are read only
2732                  * so we always do read locks
2733                  */
2734                 if (p->need_commit_sem)
2735                         down_read(&fs_info->commit_root_sem);
2736                 b = root->commit_root;
2737                 extent_buffer_get(b);
2738                 level = btrfs_header_level(b);
2739                 if (p->need_commit_sem)
2740                         up_read(&fs_info->commit_root_sem);
2741                 if (!p->skip_locking)
2742                         btrfs_tree_read_lock(b);
2743         } else {
2744                 if (p->skip_locking) {
2745                         b = btrfs_root_node(root);
2746                         level = btrfs_header_level(b);
2747                 } else {
2748                         /* we don't know the level of the root node
2749                          * until we actually have it read locked
2750                          */
2751                         b = btrfs_read_lock_root_node(root);
2752                         level = btrfs_header_level(b);
2753                         if (level <= write_lock_level) {
2754                                 /* whoops, must trade for write lock */
2755                                 btrfs_tree_read_unlock(b);
2756                                 free_extent_buffer(b);
2757                                 b = btrfs_lock_root_node(root);
2758                                 root_lock = BTRFS_WRITE_LOCK;
2759
2760                                 /* the level might have changed, check again */
2761                                 level = btrfs_header_level(b);
2762                         }
2763                 }
2764         }
2765         p->nodes[level] = b;
2766         if (!p->skip_locking)
2767                 p->locks[level] = root_lock;
2768
2769         while (b) {
2770                 level = btrfs_header_level(b);
2771
2772                 /*
2773                  * setup the path here so we can release it under lock
2774                  * contention with the cow code
2775                  */
2776                 if (cow) {
2777                         bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2778
2779                         /*
2780                          * if we don't really need to cow this block
2781                          * then we don't want to set the path blocking,
2782                          * so we test it here
2783                          */
2784                         if (!should_cow_block(trans, root, b)) {
2785                                 trans->dirty = true;
2786                                 goto cow_done;
2787                         }
2788
2789                         /*
2790                          * must have write locks on this node and the
2791                          * parent
2792                          */
2793                         if (level > write_lock_level ||
2794                             (level + 1 > write_lock_level &&
2795                             level + 1 < BTRFS_MAX_LEVEL &&
2796                             p->nodes[level + 1])) {
2797                                 write_lock_level = level + 1;
2798                                 btrfs_release_path(p);
2799                                 goto again;
2800                         }
2801
2802                         btrfs_set_path_blocking(p);
2803                         if (last_level)
2804                                 err = btrfs_cow_block(trans, root, b, NULL, 0,
2805                                                       &b);
2806                         else
2807                                 err = btrfs_cow_block(trans, root, b,
2808                                                       p->nodes[level + 1],
2809                                                       p->slots[level + 1], &b);
2810                         if (err) {
2811                                 ret = err;
2812                                 goto done;
2813                         }
2814                 }
2815 cow_done:
2816                 p->nodes[level] = b;
2817                 btrfs_clear_path_blocking(p, NULL, 0);
2818
2819                 /*
2820                  * we have a lock on b and as long as we aren't changing
2821                  * the tree, there is no way to for the items in b to change.
2822                  * It is safe to drop the lock on our parent before we
2823                  * go through the expensive btree search on b.
2824                  *
2825                  * If we're inserting or deleting (ins_len != 0), then we might
2826                  * be changing slot zero, which may require changing the parent.
2827                  * So, we can't drop the lock until after we know which slot
2828                  * we're operating on.
2829                  */
2830                 if (!ins_len && !p->keep_locks) {
2831                         int u = level + 1;
2832
2833                         if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2834                                 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2835                                 p->locks[u] = 0;
2836                         }
2837                 }
2838
2839                 ret = key_search(b, key, level, &prev_cmp, &slot);
2840                 if (ret < 0)
2841                         goto done;
2842
2843                 if (level != 0) {
2844                         int dec = 0;
2845                         if (ret && slot > 0) {
2846                                 dec = 1;
2847                                 slot -= 1;
2848                         }
2849                         p->slots[level] = slot;
2850                         err = setup_nodes_for_search(trans, root, p, b, level,
2851                                              ins_len, &write_lock_level);
2852                         if (err == -EAGAIN)
2853                                 goto again;
2854                         if (err) {
2855                                 ret = err;
2856                                 goto done;
2857                         }
2858                         b = p->nodes[level];
2859                         slot = p->slots[level];
2860
2861                         /*
2862                          * slot 0 is special, if we change the key
2863                          * we have to update the parent pointer
2864                          * which means we must have a write lock
2865                          * on the parent
2866                          */
2867                         if (slot == 0 && ins_len &&
2868                             write_lock_level < level + 1) {
2869                                 write_lock_level = level + 1;
2870                                 btrfs_release_path(p);
2871                                 goto again;
2872                         }
2873
2874                         unlock_up(p, level, lowest_unlock,
2875                                   min_write_lock_level, &write_lock_level);
2876
2877                         if (level == lowest_level) {
2878                                 if (dec)
2879                                         p->slots[level]++;
2880                                 goto done;
2881                         }
2882
2883                         err = read_block_for_search(root, p, &b, level,
2884                                                     slot, key);
2885                         if (err == -EAGAIN)
2886                                 goto again;
2887                         if (err) {
2888                                 ret = err;
2889                                 goto done;
2890                         }
2891
2892                         if (!p->skip_locking) {
2893                                 level = btrfs_header_level(b);
2894                                 if (level <= write_lock_level) {
2895                                         err = btrfs_try_tree_write_lock(b);
2896                                         if (!err) {
2897                                                 btrfs_set_path_blocking(p);
2898                                                 btrfs_tree_lock(b);
2899                                                 btrfs_clear_path_blocking(p, b,
2900                                                                   BTRFS_WRITE_LOCK);
2901                                         }
2902                                         p->locks[level] = BTRFS_WRITE_LOCK;
2903                                 } else {
2904                                         err = btrfs_tree_read_lock_atomic(b);
2905                                         if (!err) {
2906                                                 btrfs_set_path_blocking(p);
2907                                                 btrfs_tree_read_lock(b);
2908                                                 btrfs_clear_path_blocking(p, b,
2909                                                                   BTRFS_READ_LOCK);
2910                                         }
2911                                         p->locks[level] = BTRFS_READ_LOCK;
2912                                 }
2913                                 p->nodes[level] = b;
2914                         }
2915                 } else {
2916                         p->slots[level] = slot;
2917                         if (ins_len > 0 &&
2918                             btrfs_leaf_free_space(fs_info, b) < ins_len) {
2919                                 if (write_lock_level < 1) {
2920                                         write_lock_level = 1;
2921                                         btrfs_release_path(p);
2922                                         goto again;
2923                                 }
2924
2925                                 btrfs_set_path_blocking(p);
2926                                 err = split_leaf(trans, root, key,
2927                                                  p, ins_len, ret == 0);
2928                                 btrfs_clear_path_blocking(p, NULL, 0);
2929
2930                                 BUG_ON(err > 0);
2931                                 if (err) {
2932                                         ret = err;
2933                                         goto done;
2934                                 }
2935                         }
2936                         if (!p->search_for_split)
2937                                 unlock_up(p, level, lowest_unlock,
2938                                           min_write_lock_level, &write_lock_level);
2939                         goto done;
2940                 }
2941         }
2942         ret = 1;
2943 done:
2944         /*
2945          * we don't really know what they plan on doing with the path
2946          * from here on, so for now just mark it as blocking
2947          */
2948         if (!p->leave_spinning)
2949                 btrfs_set_path_blocking(p);
2950         if (ret < 0 && !p->skip_release_on_error)
2951                 btrfs_release_path(p);
2952         return ret;
2953 }
2954
2955 /*
2956  * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2957  * current state of the tree together with the operations recorded in the tree
2958  * modification log to search for the key in a previous version of this tree, as
2959  * denoted by the time_seq parameter.
2960  *
2961  * Naturally, there is no support for insert, delete or cow operations.
2962  *
2963  * The resulting path and return value will be set up as if we called
2964  * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2965  */
2966 int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2967                           struct btrfs_path *p, u64 time_seq)
2968 {
2969         struct btrfs_fs_info *fs_info = root->fs_info;
2970         struct extent_buffer *b;
2971         int slot;
2972         int ret;
2973         int err;
2974         int level;
2975         int lowest_unlock = 1;
2976         u8 lowest_level = 0;
2977         int prev_cmp = -1;
2978
2979         lowest_level = p->lowest_level;
2980         WARN_ON(p->nodes[0] != NULL);
2981
2982         if (p->search_commit_root) {
2983                 BUG_ON(time_seq);
2984                 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2985         }
2986
2987 again:
2988         b = get_old_root(root, time_seq);
2989         level = btrfs_header_level(b);
2990         p->locks[level] = BTRFS_READ_LOCK;
2991
2992         while (b) {
2993                 level = btrfs_header_level(b);
2994                 p->nodes[level] = b;
2995                 btrfs_clear_path_blocking(p, NULL, 0);
2996
2997                 /*
2998                  * we have a lock on b and as long as we aren't changing
2999                  * the tree, there is no way to for the items in b to change.
3000                  * It is safe to drop the lock on our parent before we
3001                  * go through the expensive btree search on b.
3002                  */
3003                 btrfs_unlock_up_safe(p, level + 1);
3004
3005                 /*
3006                  * Since we can unwind ebs we want to do a real search every
3007                  * time.
3008                  */
3009                 prev_cmp = -1;
3010                 ret = key_search(b, key, level, &prev_cmp, &slot);
3011
3012                 if (level != 0) {
3013                         int dec = 0;
3014                         if (ret && slot > 0) {
3015                                 dec = 1;
3016                                 slot -= 1;
3017                         }
3018                         p->slots[level] = slot;
3019                         unlock_up(p, level, lowest_unlock, 0, NULL);
3020
3021                         if (level == lowest_level) {
3022                                 if (dec)
3023                                         p->slots[level]++;
3024                                 goto done;
3025                         }
3026
3027                         err = read_block_for_search(root, p, &b, level,
3028                                                     slot, key);
3029                         if (err == -EAGAIN)
3030                                 goto again;
3031                         if (err) {
3032                                 ret = err;
3033                                 goto done;
3034                         }
3035
3036                         level = btrfs_header_level(b);
3037                         err = btrfs_tree_read_lock_atomic(b);
3038                         if (!err) {
3039                                 btrfs_set_path_blocking(p);
3040                                 btrfs_tree_read_lock(b);
3041                                 btrfs_clear_path_blocking(p, b,
3042                                                           BTRFS_READ_LOCK);
3043                         }
3044                         b = tree_mod_log_rewind(fs_info, p, b, time_seq);
3045                         if (!b) {
3046                                 ret = -ENOMEM;
3047                                 goto done;
3048                         }
3049                         p->locks[level] = BTRFS_READ_LOCK;
3050                         p->nodes[level] = b;
3051                 } else {
3052                         p->slots[level] = slot;
3053                         unlock_up(p, level, lowest_unlock, 0, NULL);
3054                         goto done;
3055                 }
3056         }
3057         ret = 1;
3058 done:
3059         if (!p->leave_spinning)
3060                 btrfs_set_path_blocking(p);
3061         if (ret < 0)
3062                 btrfs_release_path(p);
3063
3064         return ret;
3065 }
3066
3067 /*
3068  * helper to use instead of search slot if no exact match is needed but
3069  * instead the next or previous item should be returned.
3070  * When find_higher is true, the next higher item is returned, the next lower
3071  * otherwise.
3072  * When return_any and find_higher are both true, and no higher item is found,
3073  * return the next lower instead.
3074  * When return_any is true and find_higher is false, and no lower item is found,
3075  * return the next higher instead.
3076  * It returns 0 if any item is found, 1 if none is found (tree empty), and
3077  * < 0 on error
3078  */
3079 int btrfs_search_slot_for_read(struct btrfs_root *root,
3080                                const struct btrfs_key *key,
3081                                struct btrfs_path *p, int find_higher,
3082                                int return_any)
3083 {
3084         int ret;
3085         struct extent_buffer *leaf;
3086
3087 again:
3088         ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
3089         if (ret <= 0)
3090                 return ret;
3091         /*
3092          * a return value of 1 means the path is at the position where the
3093          * item should be inserted. Normally this is the next bigger item,
3094          * but in case the previous item is the last in a leaf, path points
3095          * to the first free slot in the previous leaf, i.e. at an invalid
3096          * item.
3097          */
3098         leaf = p->nodes[0];
3099
3100         if (find_higher) {
3101                 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
3102                         ret = btrfs_next_leaf(root, p);
3103                         if (ret <= 0)
3104                                 return ret;
3105                         if (!return_any)
3106                                 return 1;
3107                         /*
3108                          * no higher item found, return the next
3109                          * lower instead
3110                          */
3111                         return_any = 0;
3112                         find_higher = 0;
3113                         btrfs_release_path(p);
3114                         goto again;
3115                 }
3116         } else {
3117                 if (p->slots[0] == 0) {
3118                         ret = btrfs_prev_leaf(root, p);
3119                         if (ret < 0)
3120                                 return ret;
3121                         if (!ret) {
3122                                 leaf = p->nodes[0];
3123                                 if (p->slots[0] == btrfs_header_nritems(leaf))
3124                                         p->slots[0]--;
3125                                 return 0;
3126                         }
3127                         if (!return_any)
3128                                 return 1;
3129                         /*
3130                          * no lower item found, return the next
3131                          * higher instead
3132                          */
3133                         return_any = 0;
3134                         find_higher = 1;
3135                         btrfs_release_path(p);
3136                         goto again;
3137                 } else {
3138                         --p->slots[0];
3139                 }
3140         }
3141         return 0;
3142 }
3143
3144 /*
3145  * adjust the pointers going up the tree, starting at level
3146  * making sure the right key of each node is points to 'key'.
3147  * This is used after shifting pointers to the left, so it stops
3148  * fixing up pointers when a given leaf/node is not in slot 0 of the
3149  * higher levels
3150  *
3151  */
3152 static void fixup_low_keys(struct btrfs_fs_info *fs_info,
3153                            struct btrfs_path *path,
3154                            struct btrfs_disk_key *key, int level)
3155 {
3156         int i;
3157         struct extent_buffer *t;
3158
3159         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
3160                 int tslot = path->slots[i];
3161                 if (!path->nodes[i])
3162                         break;
3163                 t = path->nodes[i];
3164                 tree_mod_log_set_node_key(fs_info, t, tslot, 1);
3165                 btrfs_set_node_key(t, key, tslot);
3166                 btrfs_mark_buffer_dirty(path->nodes[i]);
3167                 if (tslot != 0)
3168                         break;
3169         }
3170 }
3171
3172 /*
3173  * update item key.
3174  *
3175  * This function isn't completely safe. It's the caller's responsibility
3176  * that the new key won't break the order
3177  */
3178 void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
3179                              struct btrfs_path *path,
3180                              const struct btrfs_key *new_key)
3181 {
3182         struct btrfs_disk_key disk_key;
3183         struct extent_buffer *eb;
3184         int slot;
3185
3186         eb = path->nodes[0];
3187         slot = path->slots[0];
3188         if (slot > 0) {
3189                 btrfs_item_key(eb, &disk_key, slot - 1);
3190                 BUG_ON(comp_keys(&disk_key, new_key) >= 0);
3191         }
3192         if (slot < btrfs_header_nritems(eb) - 1) {
3193                 btrfs_item_key(eb, &disk_key, slot + 1);
3194                 BUG_ON(comp_keys(&disk_key, new_key) <= 0);
3195         }
3196
3197         btrfs_cpu_key_to_disk(&disk_key, new_key);
3198         btrfs_set_item_key(eb, &disk_key, slot);
3199         btrfs_mark_buffer_dirty(eb);
3200         if (slot == 0)
3201                 fixup_low_keys(fs_info, path, &disk_key, 1);
3202 }
3203
3204 /*
3205  * try to push data from one node into the next node left in the
3206  * tree.
3207  *
3208  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
3209  * error, and > 0 if there was no room in the left hand block.
3210  */
3211 static int push_node_left(struct btrfs_trans_handle *trans,
3212                           struct btrfs_fs_info *fs_info,
3213                           struct extent_buffer *dst,
3214                           struct extent_buffer *src, int empty)
3215 {
3216         int push_items = 0;
3217         int src_nritems;
3218         int dst_nritems;
3219         int ret = 0;
3220
3221         src_nritems = btrfs_header_nritems(src);
3222         dst_nritems = btrfs_header_nritems(dst);
3223         push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
3224         WARN_ON(btrfs_header_generation(src) != trans->transid);
3225         WARN_ON(btrfs_header_generation(dst) != trans->transid);
3226
3227         if (!empty && src_nritems <= 8)
3228                 return 1;
3229
3230         if (push_items <= 0)
3231                 return 1;
3232
3233         if (empty) {
3234                 push_items = min(src_nritems, push_items);
3235                 if (push_items < src_nritems) {
3236                         /* leave at least 8 pointers in the node if
3237                          * we aren't going to empty it
3238                          */
3239                         if (src_nritems - push_items < 8) {
3240                                 if (push_items <= 8)
3241                                         return 1;
3242                                 push_items -= 8;
3243                         }
3244                 }
3245         } else
3246                 push_items = min(src_nritems - 8, push_items);
3247
3248         ret = tree_mod_log_eb_copy(fs_info, dst, src, dst_nritems, 0,
3249                                    push_items);
3250         if (ret) {
3251                 btrfs_abort_transaction(trans, ret);
3252                 return ret;
3253         }
3254         copy_extent_buffer(dst, src,
3255                            btrfs_node_key_ptr_offset(dst_nritems),
3256                            btrfs_node_key_ptr_offset(0),
3257                            push_items * sizeof(struct btrfs_key_ptr));
3258
3259         if (push_items < src_nritems) {
3260                 /*
3261                  * don't call tree_mod_log_eb_move here, key removal was already
3262                  * fully logged by tree_mod_log_eb_copy above.
3263                  */
3264                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
3265                                       btrfs_node_key_ptr_offset(push_items),
3266                                       (src_nritems - push_items) *
3267                                       sizeof(struct btrfs_key_ptr));
3268         }
3269         btrfs_set_header_nritems(src, src_nritems - push_items);
3270         btrfs_set_header_nritems(dst, dst_nritems + push_items);
3271         btrfs_mark_buffer_dirty(src);
3272         btrfs_mark_buffer_dirty(dst);
3273
3274         return ret;
3275 }
3276
3277 /*
3278  * try to push data from one node into the next node right in the
3279  * tree.
3280  *
3281  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
3282  * error, and > 0 if there was no room in the right hand block.
3283  *
3284  * this will  only push up to 1/2 the contents of the left node over
3285  */
3286 static int balance_node_right(struct btrfs_trans_handle *trans,
3287                               struct btrfs_fs_info *fs_info,
3288                               struct extent_buffer *dst,
3289                               struct extent_buffer *src)
3290 {
3291         int push_items = 0;
3292         int max_push;
3293         int src_nritems;
3294         int dst_nritems;
3295         int ret = 0;
3296
3297         WARN_ON(btrfs_header_generation(src) != trans->transid);
3298         WARN_ON(btrfs_header_generation(dst) != trans->transid);
3299
3300         src_nritems = btrfs_header_nritems(src);
3301         dst_nritems = btrfs_header_nritems(dst);
3302         push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
3303         if (push_items <= 0)
3304                 return 1;
3305
3306         if (src_nritems < 4)
3307                 return 1;
3308
3309         max_push = src_nritems / 2 + 1;
3310         /* don't try to empty the node */
3311         if (max_push >= src_nritems)
3312                 return 1;
3313
3314         if (max_push < push_items)
3315                 push_items = max_push;
3316
3317         tree_mod_log_eb_move(fs_info, dst, push_items, 0, dst_nritems);
3318         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
3319                                       btrfs_node_key_ptr_offset(0),
3320                                       (dst_nritems) *
3321                                       sizeof(struct btrfs_key_ptr));
3322
3323         ret = tree_mod_log_eb_copy(fs_info, dst, src, 0,
3324                                    src_nritems - push_items, push_items);
3325         if (ret) {
3326                 btrfs_abort_transaction(trans, ret);
3327                 return ret;
3328         }
3329         copy_extent_buffer(dst, src,
3330                            btrfs_node_key_ptr_offset(0),
3331                            btrfs_node_key_ptr_offset(src_nritems - push_items),
3332                            push_items * sizeof(struct btrfs_key_ptr));
3333
3334         btrfs_set_header_nritems(src, src_nritems - push_items);
3335         btrfs_set_header_nritems(dst, dst_nritems + push_items);
3336
3337         btrfs_mark_buffer_dirty(src);
3338         btrfs_mark_buffer_dirty(dst);
3339
3340         return ret;
3341 }
3342
3343 /*
3344  * helper function to insert a new root level in the tree.
3345  * A new node is allocated, and a single item is inserted to
3346  * point to the existing root
3347  *
3348  * returns zero on success or < 0 on failure.
3349  */
3350 static noinline int insert_new_root(struct btrfs_trans_handle *trans,
3351                            struct btrfs_root *root,
3352                            struct btrfs_path *path, int level)
3353 {
3354         struct btrfs_fs_info *fs_info = root->fs_info;
3355         u64 lower_gen;
3356         struct extent_buffer *lower;
3357         struct extent_buffer *c;
3358         struct extent_buffer *old;
3359         struct btrfs_disk_key lower_key;
3360
3361         BUG_ON(path->nodes[level]);
3362         BUG_ON(path->nodes[level-1] != root->node);
3363
3364         lower = path->nodes[level-1];
3365         if (level == 1)
3366                 btrfs_item_key(lower, &lower_key, 0);
3367         else
3368                 btrfs_node_key(lower, &lower_key, 0);
3369
3370         c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
3371                                    &lower_key, level, root->node->start, 0);
3372         if (IS_ERR(c))
3373                 return PTR_ERR(c);
3374
3375         root_add_used(root, fs_info->nodesize);
3376
3377         memzero_extent_buffer(c, 0, sizeof(struct btrfs_header));
3378         btrfs_set_header_nritems(c, 1);
3379         btrfs_set_header_level(c, level);
3380         btrfs_set_header_bytenr(c, c->start);
3381         btrfs_set_header_generation(c, trans->transid);
3382         btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
3383         btrfs_set_header_owner(c, root->root_key.objectid);
3384
3385         write_extent_buffer_fsid(c, fs_info->fsid);
3386         write_extent_buffer_chunk_tree_uuid(c, fs_info->chunk_tree_uuid);
3387
3388         btrfs_set_node_key(c, &lower_key, 0);
3389         btrfs_set_node_blockptr(c, 0, lower->start);
3390         lower_gen = btrfs_header_generation(lower);
3391         WARN_ON(lower_gen != trans->transid);
3392
3393         btrfs_set_node_ptr_generation(c, 0, lower_gen);
3394
3395         btrfs_mark_buffer_dirty(c);
3396
3397         old = root->node;
3398         tree_mod_log_set_root_pointer(root, c, 0);
3399         rcu_assign_pointer(root->node, c);
3400
3401         /* the super has an extra ref to root->node */
3402         free_extent_buffer(old);
3403
3404         add_root_to_dirty_list(root);
3405         extent_buffer_get(c);
3406         path->nodes[level] = c;
3407         path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
3408         path->slots[level] = 0;
3409         return 0;
3410 }
3411
3412 /*
3413  * worker function to insert a single pointer in a node.
3414  * the node should have enough room for the pointer already
3415  *
3416  * slot and level indicate where you want the key to go, and
3417  * blocknr is the block the key points to.
3418  */
3419 static void insert_ptr(struct btrfs_trans_handle *trans,
3420                        struct btrfs_fs_info *fs_info, struct btrfs_path *path,
3421                        struct btrfs_disk_key *key, u64 bytenr,
3422                        int slot, int level)
3423 {
3424         struct extent_buffer *lower;
3425         int nritems;
3426         int ret;
3427
3428         BUG_ON(!path->nodes[level]);
3429         btrfs_assert_tree_locked(path->nodes[level]);
3430         lower = path->nodes[level];
3431         nritems = btrfs_header_nritems(lower);
3432         BUG_ON(slot > nritems);
3433         BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(fs_info));
3434         if (slot != nritems) {
3435                 if (level)
3436                         tree_mod_log_eb_move(fs_info, lower, slot + 1,
3437                                              slot, nritems - slot);
3438                 memmove_extent_buffer(lower,
3439                               btrfs_node_key_ptr_offset(slot + 1),
3440                               btrfs_node_key_ptr_offset(slot),
3441                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
3442         }
3443         if (level) {
3444                 ret = tree_mod_log_insert_key(fs_info, lower, slot,
3445                                               MOD_LOG_KEY_ADD, GFP_NOFS);
3446                 BUG_ON(ret < 0);
3447         }
3448         btrfs_set_node_key(lower, key, slot);
3449         btrfs_set_node_blockptr(lower, slot, bytenr);
3450         WARN_ON(trans->transid == 0);
3451         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3452         btrfs_set_header_nritems(lower, nritems + 1);
3453         btrfs_mark_buffer_dirty(lower);
3454 }
3455
3456 /*
3457  * split the node at the specified level in path in two.
3458  * The path is corrected to point to the appropriate node after the split
3459  *
3460  * Before splitting this tries to make some room in the node by pushing
3461  * left and right, if either one works, it returns right away.
3462  *
3463  * returns 0 on success and < 0 on failure
3464  */
3465 static noinline int split_node(struct btrfs_trans_handle *trans,
3466                                struct btrfs_root *root,
3467                                struct btrfs_path *path, int level)
3468 {
3469         struct btrfs_fs_info *fs_info = root->fs_info;
3470         struct extent_buffer *c;
3471         struct extent_buffer *split;
3472         struct btrfs_disk_key disk_key;
3473         int mid;
3474         int ret;
3475         u32 c_nritems;
3476
3477         c = path->nodes[level];
3478         WARN_ON(btrfs_header_generation(c) != trans->transid);
3479         if (c == root->node) {
3480                 /*
3481                  * trying to split the root, lets make a new one
3482                  *
3483                  * tree mod log: We don't log_removal old root in
3484                  * insert_new_root, because that root buffer will be kept as a
3485                  * normal node. We are going to log removal of half of the
3486                  * elements below with tree_mod_log_eb_copy. We're holding a
3487                  * tree lock on the buffer, which is why we cannot race with
3488                  * other tree_mod_log users.
3489                  */
3490                 ret = insert_new_root(trans, root, path, level + 1);
3491                 if (ret)
3492                         return ret;
3493         } else {
3494                 ret = push_nodes_for_insert(trans, root, path, level);
3495                 c = path->nodes[level];
3496                 if (!ret && btrfs_header_nritems(c) <
3497                     BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
3498                         return 0;
3499                 if (ret < 0)
3500                         return ret;
3501         }
3502
3503         c_nritems = btrfs_header_nritems(c);
3504         mid = (c_nritems + 1) / 2;
3505         btrfs_node_key(c, &disk_key, mid);
3506
3507         split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
3508                         &disk_key, level, c->start, 0);
3509         if (IS_ERR(split))
3510                 return PTR_ERR(split);
3511
3512         root_add_used(root, fs_info->nodesize);
3513
3514         memzero_extent_buffer(split, 0, sizeof(struct btrfs_header));
3515         btrfs_set_header_level(split, btrfs_header_level(c));
3516         btrfs_set_header_bytenr(split, split->start);
3517         btrfs_set_header_generation(split, trans->transid);
3518         btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
3519         btrfs_set_header_owner(split, root->root_key.objectid);
3520         write_extent_buffer_fsid(split, fs_info->fsid);
3521         write_extent_buffer_chunk_tree_uuid(split, fs_info->chunk_tree_uuid);
3522
3523         ret = tree_mod_log_eb_copy(fs_info, split, c, 0, mid, c_nritems - mid);
3524         if (ret) {
3525                 btrfs_abort_transaction(trans, ret);
3526                 return ret;
3527         }
3528         copy_extent_buffer(split, c,
3529                            btrfs_node_key_ptr_offset(0),
3530                            btrfs_node_key_ptr_offset(mid),
3531                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3532         btrfs_set_header_nritems(split, c_nritems - mid);
3533         btrfs_set_header_nritems(c, mid);
3534         ret = 0;
3535
3536         btrfs_mark_buffer_dirty(c);
3537         btrfs_mark_buffer_dirty(split);
3538
3539         insert_ptr(trans, fs_info, path, &disk_key, split->start,
3540                    path->slots[level + 1] + 1, level + 1);
3541
3542         if (path->slots[level] >= mid) {
3543                 path->slots[level] -= mid;
3544                 btrfs_tree_unlock(c);
3545                 free_extent_buffer(c);
3546                 path->nodes[level] = split;
3547                 path->slots[level + 1] += 1;
3548         } else {
3549                 btrfs_tree_unlock(split);
3550                 free_extent_buffer(split);
3551         }
3552         return ret;
3553 }
3554
3555 /*
3556  * how many bytes are required to store the items in a leaf.  start
3557  * and nr indicate which items in the leaf to check.  This totals up the
3558  * space used both by the item structs and the item data
3559  */
3560 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3561 {
3562         struct btrfs_item *start_item;
3563         struct btrfs_item *end_item;
3564         struct btrfs_map_token token;
3565         int data_len;
3566         int nritems = btrfs_header_nritems(l);
3567         int end = min(nritems, start + nr) - 1;
3568
3569         if (!nr)
3570                 return 0;
3571         btrfs_init_map_token(&token);
3572         start_item = btrfs_item_nr(start);
3573         end_item = btrfs_item_nr(end);
3574         data_len = btrfs_token_item_offset(l, start_item, &token) +
3575                 btrfs_token_item_size(l, start_item, &token);
3576         data_len = data_len - btrfs_token_item_offset(l, end_item, &token);
3577         data_len += sizeof(struct btrfs_item) * nr;
3578         WARN_ON(data_len < 0);
3579         return data_len;
3580 }
3581
3582 /*
3583  * The space between the end of the leaf items and
3584  * the start of the leaf data.  IOW, how much room
3585  * the leaf has left for both items and data
3586  */
3587 noinline int btrfs_leaf_free_space(struct btrfs_fs_info *fs_info,
3588                                    struct extent_buffer *leaf)
3589 {
3590         int nritems = btrfs_header_nritems(leaf);
3591         int ret;
3592
3593         ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
3594         if (ret < 0) {
3595                 btrfs_crit(fs_info,
3596                            "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3597                            ret,
3598                            (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
3599                            leaf_space_used(leaf, 0, nritems), nritems);
3600         }
3601         return ret;
3602 }
3603
3604 /*
3605  * min slot controls the lowest index we're willing to push to the
3606  * right.  We'll push up to and including min_slot, but no lower
3607  */
3608 static noinline int __push_leaf_right(struct btrfs_fs_info *fs_info,
3609                                       struct btrfs_path *path,
3610                                       int data_size, int empty,
3611                                       struct extent_buffer *right,
3612                                       int free_space, u32 left_nritems,
3613                                       u32 min_slot)
3614 {
3615         struct extent_buffer *left = path->nodes[0];
3616         struct extent_buffer *upper = path->nodes[1];
3617         struct btrfs_map_token token;
3618         struct btrfs_disk_key disk_key;
3619         int slot;
3620         u32 i;
3621         int push_space = 0;
3622         int push_items = 0;
3623         struct btrfs_item *item;
3624         u32 nr;
3625         u32 right_nritems;
3626         u32 data_end;
3627         u32 this_item_size;
3628
3629         btrfs_init_map_token(&token);
3630
3631         if (empty)
3632                 nr = 0;
3633         else
3634                 nr = max_t(u32, 1, min_slot);
3635
3636         if (path->slots[0] >= left_nritems)
3637                 push_space += data_size;
3638
3639         slot = path->slots[1];
3640         i = left_nritems - 1;
3641         while (i >= nr) {
3642                 item = btrfs_item_nr(i);
3643
3644                 if (!empty && push_items > 0) {
3645                         if (path->slots[0] > i)
3646                                 break;
3647                         if (path->slots[0] == i) {
3648                                 int space = btrfs_leaf_free_space(fs_info, left);
3649                                 if (space + push_space * 2 > free_space)
3650                                         break;
3651                         }
3652                 }
3653
3654                 if (path->slots[0] == i)
3655                         push_space += data_size;
3656
3657                 this_item_size = btrfs_item_size(left, item);
3658                 if (this_item_size + sizeof(*item) + push_space > free_space)
3659                         break;
3660
3661                 push_items++;
3662                 push_space += this_item_size + sizeof(*item);
3663                 if (i == 0)
3664                         break;
3665                 i--;
3666         }
3667
3668         if (push_items == 0)
3669                 goto out_unlock;
3670
3671         WARN_ON(!empty && push_items == left_nritems);
3672
3673         /* push left to right */
3674         right_nritems = btrfs_header_nritems(right);
3675
3676         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3677         push_space -= leaf_data_end(fs_info, left);
3678
3679         /* make room in the right data area */
3680         data_end = leaf_data_end(fs_info, right);
3681         memmove_extent_buffer(right,
3682                               BTRFS_LEAF_DATA_OFFSET + data_end - push_space,
3683                               BTRFS_LEAF_DATA_OFFSET + data_end,
3684                               BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
3685
3686         /* copy from the left data area */
3687         copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET +
3688                      BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3689                      BTRFS_LEAF_DATA_OFFSET + leaf_data_end(fs_info, left),
3690                      push_space);
3691
3692         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3693                               btrfs_item_nr_offset(0),
3694                               right_nritems * sizeof(struct btrfs_item));
3695
3696         /* copy the items from left to right */
3697         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3698                    btrfs_item_nr_offset(left_nritems - push_items),
3699                    push_items * sizeof(struct btrfs_item));
3700
3701         /* update the item pointers */
3702         right_nritems += push_items;
3703         btrfs_set_header_nritems(right, right_nritems);
3704         push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3705         for (i = 0; i < right_nritems; i++) {
3706                 item = btrfs_item_nr(i);
3707                 push_space -= btrfs_token_item_size(right, item, &token);
3708                 btrfs_set_token_item_offset(right, item, push_space, &token);
3709         }
3710
3711         left_nritems -= push_items;
3712         btrfs_set_header_nritems(left, left_nritems);
3713
3714         if (left_nritems)
3715                 btrfs_mark_buffer_dirty(left);
3716         else
3717                 clean_tree_block(fs_info, left);
3718
3719         btrfs_mark_buffer_dirty(right);
3720
3721         btrfs_item_key(right, &disk_key, 0);
3722         btrfs_set_node_key(upper, &disk_key, slot + 1);
3723         btrfs_mark_buffer_dirty(upper);
3724
3725         /* then fixup the leaf pointer in the path */
3726         if (path->slots[0] >= left_nritems) {
3727                 path->slots[0] -= left_nritems;
3728                 if (btrfs_header_nritems(path->nodes[0]) == 0)
3729                         clean_tree_block(fs_info, path->nodes[0]);
3730                 btrfs_tree_unlock(path->nodes[0]);
3731                 free_extent_buffer(path->nodes[0]);
3732                 path->nodes[0] = right;
3733                 path->slots[1] += 1;
3734         } else {
3735                 btrfs_tree_unlock(right);
3736                 free_extent_buffer(right);
3737         }
3738         return 0;
3739
3740 out_unlock:
3741         btrfs_tree_unlock(right);
3742         free_extent_buffer(right);
3743         return 1;
3744 }
3745
3746 /*
3747  * push some data in the path leaf to the right, trying to free up at
3748  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3749  *
3750  * returns 1 if the push failed because the other node didn't have enough
3751  * room, 0 if everything worked out and < 0 if there were major errors.
3752  *
3753  * this will push starting from min_slot to the end of the leaf.  It won't
3754  * push any slot lower than min_slot
3755  */
3756 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3757                            *root, struct btrfs_path *path,
3758                            int min_data_size, int data_size,
3759                            int empty, u32 min_slot)
3760 {
3761         struct btrfs_fs_info *fs_info = root->fs_info;
3762         struct extent_buffer *left = path->nodes[0];
3763         struct extent_buffer *right;
3764         struct extent_buffer *upper;
3765         int slot;
3766         int free_space;
3767         u32 left_nritems;
3768         int ret;
3769
3770         if (!path->nodes[1])
3771                 return 1;
3772
3773         slot = path->slots[1];
3774         upper = path->nodes[1];
3775         if (slot >= btrfs_header_nritems(upper) - 1)
3776                 return 1;
3777
3778         btrfs_assert_tree_locked(path->nodes[1]);
3779
3780         right = read_node_slot(fs_info, upper, slot + 1);
3781         /*
3782          * slot + 1 is not valid or we fail to read the right node,
3783          * no big deal, just return.
3784          */
3785         if (IS_ERR(right))
3786                 return 1;
3787
3788         btrfs_tree_lock(right);
3789         btrfs_set_lock_blocking(right);
3790
3791         free_space = btrfs_leaf_free_space(fs_info, right);
3792         if (free_space < data_size)
3793                 goto out_unlock;
3794
3795         /* cow and double check */
3796         ret = btrfs_cow_block(trans, root, right, upper,
3797                               slot + 1, &right);
3798         if (ret)
3799                 goto out_unlock;
3800
3801         free_space = btrfs_leaf_free_space(fs_info, right);
3802         if (free_space < data_size)
3803                 goto out_unlock;
3804
3805         left_nritems = btrfs_header_nritems(left);
3806         if (left_nritems == 0)
3807                 goto out_unlock;
3808
3809         if (path->slots[0] == left_nritems && !empty) {
3810                 /* Key greater than all keys in the leaf, right neighbor has
3811                  * enough room for it and we're not emptying our leaf to delete
3812                  * it, therefore use right neighbor to insert the new item and
3813                  * no need to touch/dirty our left leaft. */
3814                 btrfs_tree_unlock(left);
3815                 free_extent_buffer(left);
3816                 path->nodes[0] = right;
3817                 path->slots[0] = 0;
3818                 path->slots[1]++;
3819                 return 0;
3820         }
3821
3822         return __push_leaf_right(fs_info, path, min_data_size, empty,
3823                                 right, free_space, left_nritems, min_slot);
3824 out_unlock:
3825         btrfs_tree_unlock(right);
3826         free_extent_buffer(right);
3827         return 1;
3828 }
3829
3830 /*
3831  * push some data in the path leaf to the left, trying to free up at
3832  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3833  *
3834  * max_slot can put a limit on how far into the leaf we'll push items.  The
3835  * item at 'max_slot' won't be touched.  Use (u32)-1 to make us do all the
3836  * items
3837  */
3838 static noinline int __push_leaf_left(struct btrfs_fs_info *fs_info,
3839                                      struct btrfs_path *path, int data_size,
3840                                      int empty, struct extent_buffer *left,
3841                                      int free_space, u32 right_nritems,
3842                                      u32 max_slot)
3843 {
3844         struct btrfs_disk_key disk_key;
3845         struct extent_buffer *right = path->nodes[0];
3846         int i;
3847         int push_space = 0;
3848         int push_items = 0;
3849         struct btrfs_item *item;
3850         u32 old_left_nritems;
3851         u32 nr;
3852         int ret = 0;
3853         u32 this_item_size;
3854         u32 old_left_item_size;
3855         struct btrfs_map_token token;
3856
3857         btrfs_init_map_token(&token);
3858
3859         if (empty)
3860                 nr = min(right_nritems, max_slot);
3861         else
3862                 nr = min(right_nritems - 1, max_slot);
3863
3864         for (i = 0; i < nr; i++) {
3865                 item = btrfs_item_nr(i);
3866
3867                 if (!empty && push_items > 0) {
3868                         if (path->slots[0] < i)
3869                                 break;
3870                         if (path->slots[0] == i) {
3871                                 int space = btrfs_leaf_free_space(fs_info, right);
3872                                 if (space + push_space * 2 > free_space)
3873                                         break;
3874                         }
3875                 }
3876
3877                 if (path->slots[0] == i)
3878                         push_space += data_size;
3879
3880                 this_item_size = btrfs_item_size(right, item);
3881                 if (this_item_size + sizeof(*item) + push_space > free_space)
3882                         break;
3883
3884                 push_items++;
3885                 push_space += this_item_size + sizeof(*item);
3886         }
3887
3888         if (push_items == 0) {
3889                 ret = 1;
3890                 goto out;
3891         }
3892         WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3893
3894         /* push data from right to left */
3895         copy_extent_buffer(left, right,
3896                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
3897                            btrfs_item_nr_offset(0),
3898                            push_items * sizeof(struct btrfs_item));
3899
3900         push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3901                      btrfs_item_offset_nr(right, push_items - 1);
3902
3903         copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET +
3904                      leaf_data_end(fs_info, left) - push_space,
3905                      BTRFS_LEAF_DATA_OFFSET +
3906                      btrfs_item_offset_nr(right, push_items - 1),
3907                      push_space);
3908         old_left_nritems = btrfs_header_nritems(left);
3909         BUG_ON(old_left_nritems <= 0);
3910
3911         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3912         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3913                 u32 ioff;
3914
3915                 item = btrfs_item_nr(i);
3916
3917                 ioff = btrfs_token_item_offset(left, item, &token);
3918                 btrfs_set_token_item_offset(left, item,
3919                       ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size),
3920                       &token);
3921         }
3922         btrfs_set_header_nritems(left, old_left_nritems + push_items);
3923
3924         /* fixup right node */
3925         if (push_items > right_nritems)
3926                 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3927                        right_nritems);
3928
3929         if (push_items < right_nritems) {
3930                 push_space = btrfs_item_offset_nr(right, push_items - 1) -
3931                                                   leaf_data_end(fs_info, right);
3932                 memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET +
3933                                       BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3934                                       BTRFS_LEAF_DATA_OFFSET +
3935                                       leaf_data_end(fs_info, right), push_space);
3936
3937                 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3938                               btrfs_item_nr_offset(push_items),
3939                              (btrfs_header_nritems(right) - push_items) *
3940                              sizeof(struct btrfs_item));
3941         }
3942         right_nritems -= push_items;
3943         btrfs_set_header_nritems(right, right_nritems);
3944         push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3945         for (i = 0; i < right_nritems; i++) {
3946                 item = btrfs_item_nr(i);
3947
3948                 push_space = push_space - btrfs_token_item_size(right,
3949                                                                 item, &token);
3950                 btrfs_set_token_item_offset(right, item, push_space, &token);
3951         }
3952
3953         btrfs_mark_buffer_dirty(left);
3954         if (right_nritems)
3955                 btrfs_mark_buffer_dirty(right);
3956         else
3957                 clean_tree_block(fs_info, right);
3958
3959         btrfs_item_key(right, &disk_key, 0);
3960         fixup_low_keys(fs_info, path, &disk_key, 1);
3961
3962         /* then fixup the leaf pointer in the path */
3963         if (path->slots[0] < push_items) {
3964                 path->slots[0] += old_left_nritems;
3965                 btrfs_tree_unlock(path->nodes[0]);
3966                 free_extent_buffer(path->nodes[0]);
3967                 path->nodes[0] = left;
3968                 path->slots[1] -= 1;
3969         } else {
3970                 btrfs_tree_unlock(left);
3971                 free_extent_buffer(left);
3972                 path->slots[0] -= push_items;
3973         }
3974         BUG_ON(path->slots[0] < 0);
3975         return ret;
3976 out:
3977         btrfs_tree_unlock(left);
3978         free_extent_buffer(left);
3979         return ret;
3980 }
3981
3982 /*
3983  * push some data in the path leaf to the left, trying to free up at
3984  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3985  *
3986  * max_slot can put a limit on how far into the leaf we'll push items.  The
3987  * item at 'max_slot' won't be touched.  Use (u32)-1 to make us push all the
3988  * items
3989  */
3990 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3991                           *root, struct btrfs_path *path, int min_data_size,
3992                           int data_size, int empty, u32 max_slot)
3993 {
3994         struct btrfs_fs_info *fs_info = root->fs_info;
3995         struct extent_buffer *right = path->nodes[0];
3996         struct extent_buffer *left;
3997         int slot;
3998         int free_space;
3999         u32 right_nritems;
4000         int ret = 0;
4001
4002         slot = path->slots[1];
4003         if (slot == 0)
4004                 return 1;
4005         if (!path->nodes[1])
4006                 return 1;
4007
4008         right_nritems = btrfs_header_nritems(right);
4009         if (right_nritems == 0)
4010                 return 1;
4011
4012         btrfs_assert_tree_locked(path->nodes[1]);
4013
4014         left = read_node_slot(fs_info, path->nodes[1], slot - 1);
4015         /*
4016          * slot - 1 is not valid or we fail to read the left node,
4017          * no big deal, just return.
4018          */
4019         if (IS_ERR(left))
4020                 return 1;
4021
4022         btrfs_tree_lock(left);
4023         btrfs_set_lock_blocking(left);
4024
4025         free_space = btrfs_leaf_free_space(fs_info, left);
4026         if (free_space < data_size) {
4027                 ret = 1;
4028                 goto out;
4029         }
4030
4031         /* cow and double check */
4032         ret = btrfs_cow_block(trans, root, left,
4033                               path->nodes[1], slot - 1, &left);
4034         if (ret) {
4035                 /* we hit -ENOSPC, but it isn't fatal here */
4036                 if (ret == -ENOSPC)
4037                         ret = 1;
4038                 goto out;
4039         }
4040
4041         free_space = btrfs_leaf_free_space(fs_info, left);
4042         if (free_space < data_size) {
4043                 ret = 1;
4044                 goto out;
4045         }
4046
4047         return __push_leaf_left(fs_info, path, min_data_size,
4048                                empty, left, free_space, right_nritems,
4049                                max_slot);
4050 out:
4051         btrfs_tree_unlock(left);
4052         free_extent_buffer(left);
4053         return ret;
4054 }
4055
4056 /*
4057  * split the path's leaf in two, making sure there is at least data_size
4058  * available for the resulting leaf level of the path.
4059  */
4060 static noinline void copy_for_split(struct btrfs_trans_handle *trans,
4061                                     struct btrfs_fs_info *fs_info,
4062                                     struct btrfs_path *path,
4063                                     struct extent_buffer *l,
4064                                     struct extent_buffer *right,
4065                                     int slot, int mid, int nritems)
4066 {
4067         int data_copy_size;
4068         int rt_data_off;
4069         int i;
4070         struct btrfs_disk_key disk_key;
4071         struct btrfs_map_token token;
4072
4073         btrfs_init_map_token(&token);
4074
4075         nritems = nritems - mid;
4076         btrfs_set_header_nritems(right, nritems);
4077         data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(fs_info, l);
4078
4079         copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
4080                            btrfs_item_nr_offset(mid),
4081                            nritems * sizeof(struct btrfs_item));
4082
4083         copy_extent_buffer(right, l,
4084                      BTRFS_LEAF_DATA_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) -
4085                      data_copy_size, BTRFS_LEAF_DATA_OFFSET +
4086                      leaf_data_end(fs_info, l), data_copy_size);
4087
4088         rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_end_nr(l, mid);
4089
4090         for (i = 0; i < nritems; i++) {
4091                 struct btrfs_item *item = btrfs_item_nr(i);
4092                 u32 ioff;
4093
4094                 ioff = btrfs_token_item_offset(right, item, &token);
4095                 btrfs_set_token_item_offset(right, item,
4096                                             ioff + rt_data_off, &token);
4097         }
4098
4099         btrfs_set_header_nritems(l, mid);
4100         btrfs_item_key(right, &disk_key, 0);
4101         insert_ptr(trans, fs_info, path, &disk_key, right->start,
4102                    path->slots[1] + 1, 1);
4103
4104         btrfs_mark_buffer_dirty(right);
4105         btrfs_mark_buffer_dirty(l);
4106         BUG_ON(path->slots[0] != slot);
4107
4108         if (mid <= slot) {
4109                 btrfs_tree_unlock(path->nodes[0]);
4110                 free_extent_buffer(path->nodes[0]);
4111                 path->nodes[0] = right;
4112                 path->slots[0] -= mid;
4113                 path->slots[1] += 1;
4114         } else {
4115                 btrfs_tree_unlock(right);
4116                 free_extent_buffer(right);
4117         }
4118
4119         BUG_ON(path->slots[0] < 0);
4120 }
4121
4122 /*
4123  * double splits happen when we need to insert a big item in the middle
4124  * of a leaf.  A double split can leave us with 3 mostly empty leaves:
4125  * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
4126  *          A                 B                 C
4127  *
4128  * We avoid this by trying to push the items on either side of our target
4129  * into the adjacent leaves.  If all goes well we can avoid the double split
4130  * completely.
4131  */
4132 static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
4133                                           struct btrfs_root *root,
4134                                           struct btrfs_path *path,
4135                                           int data_size)
4136 {
4137         struct btrfs_fs_info *fs_info = root->fs_info;
4138         int ret;
4139         int progress = 0;
4140         int slot;
4141         u32 nritems;
4142         int space_needed = data_size;
4143
4144         slot = path->slots[0];
4145         if (slot < btrfs_header_nritems(path->nodes[0]))
4146                 space_needed -= btrfs_leaf_free_space(fs_info, path->nodes[0]);
4147
4148         /*
4149          * try to push all the items after our slot into the
4150          * right leaf
4151          */
4152         ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
4153         if (ret < 0)
4154                 return ret;
4155
4156         if (ret == 0)
4157                 progress++;
4158
4159         nritems = btrfs_header_nritems(path->nodes[0]);
4160         /*
4161          * our goal is to get our slot at the start or end of a leaf.  If
4162          * we've done so we're done
4163          */
4164         if (path->slots[0] == 0 || path->slots[0] == nritems)
4165                 return 0;
4166
4167         if (btrfs_leaf_free_space(fs_info, path->nodes[0]) >= data_size)
4168                 return 0;
4169
4170         /* try to push all the items before our slot into the next leaf */
4171         slot = path->slots[0];
4172         space_needed = data_size;
4173         if (slot > 0)
4174                 space_needed -= btrfs_leaf_free_space(fs_info, path->nodes[0]);
4175         ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
4176         if (ret < 0)
4177                 return ret;
4178
4179         if (ret == 0)
4180                 progress++;
4181
4182         if (progress)
4183                 return 0;
4184         return 1;
4185 }
4186
4187 /*
4188  * split the path's leaf in two, making sure there is at least data_size
4189  * available for the resulting leaf level of the path.
4190  *
4191  * returns 0 if all went well and < 0 on failure.
4192  */
4193 static noinline int split_leaf(struct btrfs_trans_handle *trans,
4194                                struct btrfs_root *root,
4195                                const struct btrfs_key *ins_key,
4196                                struct btrfs_path *path, int data_size,
4197                                int extend)
4198 {
4199         struct btrfs_disk_key disk_key;
4200         struct extent_buffer *l;
4201         u32 nritems;
4202         int mid;
4203         int slot;
4204         struct extent_buffer *right;
4205         struct btrfs_fs_info *fs_info = root->fs_info;
4206         int ret = 0;
4207         int wret;
4208         int split;
4209         int num_doubles = 0;
4210         int tried_avoid_double = 0;
4211
4212         l = path->nodes[0];
4213         slot = path->slots[0];
4214         if (extend && data_size + btrfs_item_size_nr(l, slot) +
4215             sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
4216                 return -EOVERFLOW;
4217
4218         /* first try to make some room by pushing left and right */
4219         if (data_size && path->nodes[1]) {
4220                 int space_needed = data_size;
4221
4222                 if (slot < btrfs_header_nritems(l))
4223                         space_needed -= btrfs_leaf_free_space(fs_info, l);
4224
4225                 wret = push_leaf_right(trans, root, path, space_needed,
4226                                        space_needed, 0, 0);
4227                 if (wret < 0)
4228                         return wret;
4229                 if (wret) {
4230                         space_needed = data_size;
4231                         if (slot > 0)
4232                                 space_needed -= btrfs_leaf_free_space(fs_info,
4233                                                                       l);
4234                         wret = push_leaf_left(trans, root, path, space_needed,
4235                                               space_needed, 0, (u32)-1);
4236                         if (wret < 0)
4237                                 return wret;
4238                 }
4239                 l = path->nodes[0];
4240
4241                 /* did the pushes work? */
4242                 if (btrfs_leaf_free_space(fs_info, l) >= data_size)
4243                         return 0;
4244         }
4245
4246         if (!path->nodes[1]) {
4247                 ret = insert_new_root(trans, root, path, 1);
4248                 if (ret)
4249                         return ret;
4250         }
4251 again:
4252         split = 1;
4253         l = path->nodes[0];
4254         slot = path->slots[0];
4255         nritems = btrfs_header_nritems(l);
4256         mid = (nritems + 1) / 2;
4257
4258         if (mid <= slot) {
4259                 if (nritems == 1 ||
4260                     leaf_space_used(l, mid, nritems - mid) + data_size >
4261                         BTRFS_LEAF_DATA_SIZE(fs_info)) {
4262                         if (slot >= nritems) {
4263                                 split = 0;
4264                         } else {
4265                                 mid = slot;
4266                                 if (mid != nritems &&
4267                                     leaf_space_used(l, mid, nritems - mid) +
4268                                     data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4269                                         if (data_size && !tried_avoid_double)
4270                                                 goto push_for_double;
4271                                         split = 2;
4272                                 }
4273                         }
4274                 }
4275         } else {
4276                 if (leaf_space_used(l, 0, mid) + data_size >
4277                         BTRFS_LEAF_DATA_SIZE(fs_info)) {
4278                         if (!extend && data_size && slot == 0) {
4279                                 split = 0;
4280                         } else if ((extend || !data_size) && slot == 0) {
4281                                 mid = 1;
4282                         } else {
4283                                 mid = slot;
4284                                 if (mid != nritems &&
4285                                     leaf_space_used(l, mid, nritems - mid) +
4286                                     data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4287                                         if (data_size && !tried_avoid_double)
4288                                                 goto push_for_double;
4289                                         split = 2;
4290                                 }
4291                         }
4292                 }
4293         }
4294
4295         if (split == 0)
4296                 btrfs_cpu_key_to_disk(&disk_key, ins_key);
4297         else
4298                 btrfs_item_key(l, &disk_key, mid);
4299
4300         right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
4301                         &disk_key, 0, l->start, 0);
4302         if (IS_ERR(right))
4303                 return PTR_ERR(right);
4304
4305         root_add_used(root, fs_info->nodesize);
4306
4307         memzero_extent_buffer(right, 0, sizeof(struct btrfs_header));
4308         btrfs_set_header_bytenr(right, right->start);
4309         btrfs_set_header_generation(right, trans->transid);
4310         btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
4311         btrfs_set_header_owner(right, root->root_key.objectid);
4312         btrfs_set_header_level(right, 0);
4313         write_extent_buffer_fsid(right, fs_info->fsid);
4314         write_extent_buffer_chunk_tree_uuid(right, fs_info->chunk_tree_uuid);
4315
4316         if (split == 0) {
4317                 if (mid <= slot) {
4318                         btrfs_set_header_nritems(right, 0);
4319                         insert_ptr(trans, fs_info, path, &disk_key,
4320                                    right->start, path->slots[1] + 1, 1);
4321                         btrfs_tree_unlock(path->nodes[0]);
4322                         free_extent_buffer(path->nodes[0]);
4323                         path->nodes[0] = right;
4324                         path->slots[0] = 0;
4325                         path->slots[1] += 1;
4326                 } else {
4327                         btrfs_set_header_nritems(right, 0);
4328                         insert_ptr(trans, fs_info, path, &disk_key,
4329                                    right->start, path->slots[1], 1);
4330                         btrfs_tree_unlock(path->nodes[0]);
4331                         free_extent_buffer(path->nodes[0]);
4332                         path->nodes[0] = right;
4333                         path->slots[0] = 0;
4334                         if (path->slots[1] == 0)
4335                                 fixup_low_keys(fs_info, path, &disk_key, 1);
4336                 }
4337                 /*
4338                  * We create a new leaf 'right' for the required ins_len and
4339                  * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
4340                  * the content of ins_len to 'right'.
4341                  */
4342                 return ret;
4343         }
4344
4345         copy_for_split(trans, fs_info, path, l, right, slot, mid, nritems);
4346
4347         if (split == 2) {
4348                 BUG_ON(num_doubles != 0);
4349                 num_doubles++;
4350                 goto again;
4351         }
4352
4353         return 0;
4354
4355 push_for_double:
4356         push_for_double_split(trans, root, path, data_size);
4357         tried_avoid_double = 1;
4358         if (btrfs_leaf_free_space(fs_info, path->nodes[0]) >= data_size)
4359                 return 0;
4360         goto again;
4361 }
4362
4363 static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
4364                                          struct btrfs_root *root,
4365                                          struct btrfs_path *path, int ins_len)
4366 {
4367         struct btrfs_fs_info *fs_info = root->fs_info;
4368         struct btrfs_key key;
4369         struct extent_buffer *leaf;
4370         struct btrfs_file_extent_item *fi;
4371         u64 extent_len = 0;
4372         u32 item_size;
4373         int ret;
4374
4375         leaf = path->nodes[0];
4376         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4377
4378         BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
4379                key.type != BTRFS_EXTENT_CSUM_KEY);
4380
4381         if (btrfs_leaf_free_space(fs_info, leaf) >= ins_len)
4382                 return 0;
4383
4384         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4385         if (key.type == BTRFS_EXTENT_DATA_KEY) {
4386                 fi = btrfs_item_ptr(leaf, path->slots[0],
4387                                     struct btrfs_file_extent_item);
4388                 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
4389         }
4390         btrfs_release_path(path);
4391
4392         path->keep_locks = 1;
4393         path->search_for_split = 1;
4394         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
4395         path->search_for_split = 0;
4396         if (ret > 0)
4397                 ret = -EAGAIN;
4398         if (ret < 0)
4399                 goto err;
4400
4401         ret = -EAGAIN;
4402         leaf = path->nodes[0];
4403         /* if our item isn't there, return now */
4404         if (item_size != btrfs_item_size_nr(leaf, path->slots[0]))
4405                 goto err;
4406
4407         /* the leaf has  changed, it now has room.  return now */
4408         if (btrfs_leaf_free_space(fs_info, path->nodes[0]) >= ins_len)
4409                 goto err;
4410
4411         if (key.type == BTRFS_EXTENT_DATA_KEY) {
4412                 fi = btrfs_item_ptr(leaf, path->slots[0],
4413                                     struct btrfs_file_extent_item);
4414                 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
4415                         goto err;
4416         }
4417
4418         btrfs_set_path_blocking(path);
4419         ret = split_leaf(trans, root, &key, path, ins_len, 1);
4420         if (ret)
4421                 goto err;
4422
4423         path->keep_locks = 0;
4424         btrfs_unlock_up_safe(path, 1);
4425         return 0;
4426 err:
4427         path->keep_locks = 0;
4428         return ret;
4429 }
4430
4431 static noinline int split_item(struct btrfs_fs_info *fs_info,
4432                                struct btrfs_path *path,
4433                                const struct btrfs_key *new_key,
4434                                unsigned long split_offset)
4435 {
4436         struct extent_buffer *leaf;
4437         struct btrfs_item *item;
4438         struct btrfs_item *new_item;
4439         int slot;
4440         char *buf;
4441         u32 nritems;
4442         u32 item_size;
4443         u32 orig_offset;
4444         struct btrfs_disk_key disk_key;
4445
4446         leaf = path->nodes[0];
4447         BUG_ON(btrfs_leaf_free_space(fs_info, leaf) < sizeof(struct btrfs_item));
4448
4449         btrfs_set_path_blocking(path);
4450
4451         item = btrfs_item_nr(path->slots[0]);
4452         orig_offset = btrfs_item_offset(leaf, item);
4453         item_size = btrfs_item_size(leaf, item);
4454
4455         buf = kmalloc(item_size, GFP_NOFS);
4456         if (!buf)
4457                 return -ENOMEM;
4458
4459         read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
4460                             path->slots[0]), item_size);
4461
4462         slot = path->slots[0] + 1;
4463         nritems = btrfs_header_nritems(leaf);
4464         if (slot != nritems) {
4465                 /* shift the items */
4466                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
4467                                 btrfs_item_nr_offset(slot),
4468                                 (nritems - slot) * sizeof(struct btrfs_item));
4469         }
4470
4471         btrfs_cpu_key_to_disk(&disk_key, new_key);
4472         btrfs_set_item_key(leaf, &disk_key, slot);
4473
4474         new_item = btrfs_item_nr(slot);
4475
4476         btrfs_set_item_offset(leaf, new_item, orig_offset);
4477         btrfs_set_item_size(leaf, new_item, item_size - split_offset);
4478
4479         btrfs_set_item_offset(leaf, item,
4480                               orig_offset + item_size - split_offset);
4481         btrfs_set_item_size(leaf, item, split_offset);
4482
4483         btrfs_set_header_nritems(leaf, nritems + 1);
4484
4485         /* write the data for the start of the original item */
4486         write_extent_buffer(leaf, buf,
4487                             btrfs_item_ptr_offset(leaf, path->slots[0]),
4488                             split_offset);
4489
4490         /* write the data for the new item */
4491         write_extent_buffer(leaf, buf + split_offset,
4492                             btrfs_item_ptr_offset(leaf, slot),
4493                             item_size - split_offset);
4494         btrfs_mark_buffer_dirty(leaf);
4495
4496         BUG_ON(btrfs_leaf_free_space(fs_info, leaf) < 0);
4497         kfree(buf);
4498         return 0;
4499 }
4500
4501 /*
4502  * This function splits a single item into two items,
4503  * giving 'new_key' to the new item and splitting the
4504  * old one at split_offset (from the start of the item).
4505  *
4506  * The path may be released by this operation.  After
4507  * the split, the path is pointing to the old item.  The
4508  * new item is going to be in the same node as the old one.
4509  *
4510  * Note, the item being split must be smaller enough to live alone on
4511  * a tree block with room for one extra struct btrfs_item
4512  *
4513  * This allows us to split the item in place, keeping a lock on the
4514  * leaf the entire time.
4515  */
4516 int btrfs_split_item(struct btrfs_trans_handle *trans,
4517                      struct btrfs_root *root,
4518                      struct btrfs_path *path,
4519                      const struct btrfs_key *new_key,
4520                      unsigned long split_offset)
4521 {
4522         int ret;
4523         ret = setup_leaf_for_split(trans, root, path,
4524                                    sizeof(struct btrfs_item));
4525         if (ret)
4526                 return ret;
4527
4528         ret = split_item(root->fs_info, path, new_key, split_offset);
4529         return ret;
4530 }
4531
4532 /*
4533  * This function duplicate a item, giving 'new_key' to the new item.
4534  * It guarantees both items live in the same tree leaf and the new item
4535  * is contiguous with the original item.
4536  *
4537  * This allows us to split file extent in place, keeping a lock on the
4538  * leaf the entire time.
4539  */
4540 int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4541                          struct btrfs_root *root,
4542                          struct btrfs_path *path,
4543                          const struct btrfs_key *new_key)
4544 {
4545         struct extent_buffer *leaf;
4546         int ret;
4547         u32 item_size;
4548
4549         leaf = path->nodes[0];
4550         item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4551         ret = setup_leaf_for_split(trans, root, path,
4552                                    item_size + sizeof(struct btrfs_item));
4553         if (ret)
4554                 return ret;
4555
4556         path->slots[0]++;
4557         setup_items_for_insert(root, path, new_key, &item_size,
4558                                item_size, item_size +
4559                                sizeof(struct btrfs_item), 1);
4560         leaf = path->nodes[0];
4561         memcpy_extent_buffer(leaf,
4562                              btrfs_item_ptr_offset(leaf, path->slots[0]),
4563                              btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4564                              item_size);
4565         return 0;
4566 }
4567
4568 /*
4569  * make the item pointed to by the path smaller.  new_size indicates
4570  * how small to make it, and from_end tells us if we just chop bytes
4571  * off the end of the item or if we shift the item to chop bytes off
4572  * the front.
4573  */
4574 void btrfs_truncate_item(struct btrfs_fs_info *fs_info,
4575                          struct btrfs_path *path, u32 new_size, int from_end)
4576 {
4577         int slot;
4578         struct extent_buffer *leaf;
4579         struct btrfs_item *item;
4580         u32 nritems;
4581         unsigned int data_end;
4582         unsigned int old_data_start;
4583         unsigned int old_size;
4584         unsigned int size_diff;
4585         int i;
4586         struct btrfs_map_token token;
4587
4588         btrfs_init_map_token(&token);
4589
4590         leaf = path->nodes[0];
4591         slot = path->slots[0];
4592
4593         old_size = btrfs_item_size_nr(leaf, slot);
4594         if (old_size == new_size)
4595                 return;
4596
4597         nritems = btrfs_header_nritems(leaf);
4598         data_end = leaf_data_end(fs_info, leaf);
4599
4600         old_data_start = btrfs_item_offset_nr(leaf, slot);
4601
4602         size_diff = old_size - new_size;
4603
4604         BUG_ON(slot < 0);
4605         BUG_ON(slot >= nritems);
4606
4607         /*
4608          * item0..itemN ... dataN.offset..dataN.size .. data0.size
4609          */
4610         /* first correct the data pointers */
4611         for (i = slot; i < nritems; i++) {
4612                 u32 ioff;
4613                 item = btrfs_item_nr(i);
4614
4615                 ioff = btrfs_token_item_offset(leaf, item, &token);
4616                 btrfs_set_token_item_offset(leaf, item,
4617                                             ioff + size_diff, &token);
4618         }
4619
4620         /* shift the data */
4621         if (from_end) {
4622                 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4623                               data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4624                               data_end, old_data_start + new_size - data_end);
4625         } else {
4626                 struct btrfs_disk_key disk_key;
4627                 u64 offset;
4628
4629                 btrfs_item_key(leaf, &disk_key, slot);
4630
4631                 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4632                         unsigned long ptr;
4633                         struct btrfs_file_extent_item *fi;
4634
4635                         fi = btrfs_item_ptr(leaf, slot,
4636                                             struct btrfs_file_extent_item);
4637                         fi = (struct btrfs_file_extent_item *)(
4638                              (unsigned long)fi - size_diff);
4639
4640                         if (btrfs_file_extent_type(leaf, fi) ==
4641                             BTRFS_FILE_EXTENT_INLINE) {
4642                                 ptr = btrfs_item_ptr_offset(leaf, slot);
4643                                 memmove_extent_buffer(leaf, ptr,
4644                                       (unsigned long)fi,
4645                                       BTRFS_FILE_EXTENT_INLINE_DATA_START);
4646                         }
4647                 }
4648
4649                 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4650                               data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4651                               data_end, old_data_start - data_end);
4652
4653                 offset = btrfs_disk_key_offset(&disk_key);
4654                 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4655                 btrfs_set_item_key(leaf, &disk_key, slot);
4656                 if (slot == 0)
4657                         fixup_low_keys(fs_info, path, &disk_key, 1);
4658         }
4659
4660         item = btrfs_item_nr(slot);
4661         btrfs_set_item_size(leaf, item, new_size);
4662         btrfs_mark_buffer_dirty(leaf);
4663
4664         if (btrfs_leaf_free_space(fs_info, leaf) < 0) {
4665                 btrfs_print_leaf(leaf);
4666                 BUG();
4667         }
4668 }
4669
4670 /*
4671  * make the item pointed to by the path bigger, data_size is the added size.
4672  */
4673 void btrfs_extend_item(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
4674                        u32 data_size)
4675 {
4676         int slot;
4677         struct extent_buffer *leaf;
4678         struct btrfs_item *item;
4679         u32 nritems;
4680         unsigned int data_end;
4681         unsigned int old_data;
4682         unsigned int old_size;
4683         int i;
4684         struct btrfs_map_token token;
4685
4686         btrfs_init_map_token(&token);
4687
4688         leaf = path->nodes[0];
4689
4690         nritems = btrfs_header_nritems(leaf);
4691         data_end = leaf_data_end(fs_info, leaf);
4692
4693         if (btrfs_leaf_free_space(fs_info, leaf) < data_size) {
4694                 btrfs_print_leaf(leaf);
4695                 BUG();
4696         }
4697         slot = path->slots[0];
4698         old_data = btrfs_item_end_nr(leaf, slot);
4699
4700         BUG_ON(slot < 0);
4701         if (slot >= nritems) {
4702                 btrfs_print_leaf(leaf);
4703                 btrfs_crit(fs_info, "slot %d too large, nritems %d",
4704                            slot, nritems);
4705                 BUG_ON(1);
4706         }
4707
4708         /*
4709          * item0..itemN ... dataN.offset..dataN.size .. data0.size
4710          */
4711         /* first correct the data pointers */
4712         for (i = slot; i < nritems; i++) {
4713                 u32 ioff;
4714                 item = btrfs_item_nr(i);
4715
4716                 ioff = btrfs_token_item_offset(leaf, item, &token);
4717                 btrfs_set_token_item_offset(leaf, item,
4718                                             ioff - data_size, &token);
4719         }
4720
4721         /* shift the data */
4722         memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4723                       data_end - data_size, BTRFS_LEAF_DATA_OFFSET +
4724                       data_end, old_data - data_end);
4725
4726         data_end = old_data;
4727         old_size = btrfs_item_size_nr(leaf, slot);
4728         item = btrfs_item_nr(slot);
4729         btrfs_set_item_size(leaf, item, old_size + data_size);
4730         btrfs_mark_buffer_dirty(leaf);
4731
4732         if (btrfs_leaf_free_space(fs_info, leaf) < 0) {
4733                 btrfs_print_leaf(leaf);
4734                 BUG();
4735         }
4736 }
4737
4738 /*
4739  * this is a helper for btrfs_insert_empty_items, the main goal here is
4740  * to save stack depth by doing the bulk of the work in a function
4741  * that doesn't call btrfs_search_slot
4742  */
4743 void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
4744                             const struct btrfs_key *cpu_key, u32 *data_size,
4745                             u32 total_data, u32 total_size, int nr)
4746 {
4747         struct btrfs_fs_info *fs_info = root->fs_info;
4748         struct btrfs_item *item;
4749         int i;
4750         u32 nritems;
4751         unsigned int data_end;
4752         struct btrfs_disk_key disk_key;
4753         struct extent_buffer *leaf;
4754         int slot;
4755         struct btrfs_map_token token;
4756
4757         if (path->slots[0] == 0) {
4758                 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4759                 fixup_low_keys(fs_info, path, &disk_key, 1);
4760         }
4761         btrfs_unlock_up_safe(path, 1);
4762
4763         btrfs_init_map_token(&token);
4764
4765         leaf = path->nodes[0];
4766         slot = path->slots[0];
4767
4768         nritems = btrfs_header_nritems(leaf);
4769         data_end = leaf_data_end(fs_info, leaf);
4770
4771         if (btrfs_leaf_free_space(fs_info, leaf) < total_size) {
4772                 btrfs_print_leaf(leaf);
4773                 btrfs_crit(fs_info, "not enough freespace need %u have %d",
4774                            total_size, btrfs_leaf_free_space(fs_info, leaf));
4775                 BUG();
4776         }
4777
4778         if (slot != nritems) {
4779                 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4780
4781                 if (old_data < data_end) {
4782                         btrfs_print_leaf(leaf);
4783                         btrfs_crit(fs_info, "slot %d old_data %d data_end %d",
4784                                    slot, old_data, data_end);
4785                         BUG_ON(1);
4786                 }
4787                 /*
4788                  * item0..itemN ... dataN.offset..dataN.size .. data0.size
4789                  */
4790                 /* first correct the data pointers */
4791                 for (i = slot; i < nritems; i++) {
4792                         u32 ioff;
4793
4794                         item = btrfs_item_nr(i);
4795                         ioff = btrfs_token_item_offset(leaf, item, &token);
4796                         btrfs_set_token_item_offset(leaf, item,
4797                                                     ioff - total_data, &token);
4798                 }
4799                 /* shift the items */
4800                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4801                               btrfs_item_nr_offset(slot),
4802                               (nritems - slot) * sizeof(struct btrfs_item));
4803
4804                 /* shift the data */
4805                 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4806                               data_end - total_data, BTRFS_LEAF_DATA_OFFSET +
4807                               data_end, old_data - data_end);
4808                 data_end = old_data;
4809         }
4810
4811         /* setup the item for the new data */
4812         for (i = 0; i < nr; i++) {
4813                 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4814                 btrfs_set_item_key(leaf, &disk_key, slot + i);
4815                 item = btrfs_item_nr(slot + i);
4816                 btrfs_set_token_item_offset(leaf, item,
4817                                             data_end - data_size[i], &token);
4818                 data_end -= data_size[i];
4819                 btrfs_set_token_item_size(leaf, item, data_size[i], &token);
4820         }
4821
4822         btrfs_set_header_nritems(leaf, nritems + nr);
4823         btrfs_mark_buffer_dirty(leaf);
4824
4825         if (btrfs_leaf_free_space(fs_info, leaf) < 0) {
4826                 btrfs_print_leaf(leaf);
4827                 BUG();
4828         }
4829 }
4830
4831 /*
4832  * Given a key and some data, insert items into the tree.
4833  * This does all the path init required, making room in the tree if needed.
4834  */
4835 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4836                             struct btrfs_root *root,
4837                             struct btrfs_path *path,
4838                             const struct btrfs_key *cpu_key, u32 *data_size,
4839                             int nr)
4840 {
4841         int ret = 0;
4842         int slot;
4843         int i;
4844         u32 total_size = 0;
4845         u32 total_data = 0;
4846
4847         for (i = 0; i < nr; i++)
4848                 total_data += data_size[i];
4849
4850         total_size = total_data + (nr * sizeof(struct btrfs_item));
4851         ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4852         if (ret == 0)
4853                 return -EEXIST;
4854         if (ret < 0)
4855                 return ret;
4856
4857         slot = path->slots[0];
4858         BUG_ON(slot < 0);
4859
4860         setup_items_for_insert(root, path, cpu_key, data_size,
4861                                total_data, total_size, nr);
4862         return 0;
4863 }
4864
4865 /*
4866  * Given a key and some data, insert an item into the tree.
4867  * This does all the path init required, making room in the tree if needed.
4868  */
4869 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4870                       const struct btrfs_key *cpu_key, void *data,
4871                       u32 data_size)
4872 {
4873         int ret = 0;
4874         struct btrfs_path *path;
4875         struct extent_buffer *leaf;
4876         unsigned long ptr;
4877
4878         path = btrfs_alloc_path();
4879         if (!path)
4880                 return -ENOMEM;
4881         ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4882         if (!ret) {
4883                 leaf = path->nodes[0];
4884                 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4885                 write_extent_buffer(leaf, data, ptr, data_size);
4886                 btrfs_mark_buffer_dirty(leaf);
4887         }
4888         btrfs_free_path(path);
4889         return ret;
4890 }
4891
4892 /*
4893  * delete the pointer from a given node.
4894  *
4895  * the tree should have been previously balanced so the deletion does not
4896  * empty a node.
4897  */
4898 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
4899                     int level, int slot)
4900 {
4901         struct btrfs_fs_info *fs_info = root->fs_info;
4902         struct extent_buffer *parent = path->nodes[level];
4903         u32 nritems;
4904         int ret;
4905
4906         nritems = btrfs_header_nritems(parent);
4907         if (slot != nritems - 1) {
4908                 if (level)
4909                         tree_mod_log_eb_move(fs_info, parent, slot,
4910                                              slot + 1, nritems - slot - 1);
4911                 memmove_extent_buffer(parent,
4912                               btrfs_node_key_ptr_offset(slot),
4913                               btrfs_node_key_ptr_offset(slot + 1),
4914                               sizeof(struct btrfs_key_ptr) *
4915                               (nritems - slot - 1));
4916         } else if (level) {
4917                 ret = tree_mod_log_insert_key(fs_info, parent, slot,
4918                                               MOD_LOG_KEY_REMOVE, GFP_NOFS);
4919                 BUG_ON(ret < 0);
4920         }
4921
4922         nritems--;
4923         btrfs_set_header_nritems(parent, nritems);
4924         if (nritems == 0 && parent == root->node) {
4925                 BUG_ON(btrfs_header_level(root->node) != 1);
4926                 /* just turn the root into a leaf and break */
4927                 btrfs_set_header_level(root->node, 0);
4928         } else if (slot == 0) {
4929                 struct btrfs_disk_key disk_key;
4930
4931                 btrfs_node_key(parent, &disk_key, 0);
4932                 fixup_low_keys(fs_info, path, &disk_key, level + 1);
4933         }
4934         btrfs_mark_buffer_dirty(parent);
4935 }
4936
4937 /*
4938  * a helper function to delete the leaf pointed to by path->slots[1] and
4939  * path->nodes[1].
4940  *
4941  * This deletes the pointer in path->nodes[1] and frees the leaf
4942  * block extent.  zero is returned if it all worked out, < 0 otherwise.
4943  *
4944  * The path must have already been setup for deleting the leaf, including
4945  * all the proper balancing.  path->nodes[1] must be locked.
4946  */
4947 static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4948                                     struct btrfs_root *root,
4949                                     struct btrfs_path *path,
4950                                     struct extent_buffer *leaf)
4951 {
4952         WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4953         del_ptr(root, path, 1, path->slots[1]);
4954
4955         /*
4956          * btrfs_free_extent is expensive, we want to make sure we
4957          * aren't holding any locks when we call it
4958          */
4959         btrfs_unlock_up_safe(path, 0);
4960
4961         root_sub_used(root, leaf->len);
4962
4963         extent_buffer_get(leaf);
4964         btrfs_free_tree_block(trans, root, leaf, 0, 1);
4965         free_extent_buffer_stale(leaf);
4966 }
4967 /*
4968  * delete the item at the leaf level in path.  If that empties
4969  * the leaf, remove it from the tree
4970  */
4971 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4972                     struct btrfs_path *path, int slot, int nr)
4973 {
4974         struct btrfs_fs_info *fs_info = root->fs_info;
4975         struct extent_buffer *leaf;
4976         struct btrfs_item *item;
4977         u32 last_off;
4978         u32 dsize = 0;
4979         int ret = 0;
4980         int wret;
4981         int i;
4982         u32 nritems;
4983         struct btrfs_map_token token;
4984
4985         btrfs_init_map_token(&token);
4986
4987         leaf = path->nodes[0];
4988         last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4989
4990         for (i = 0; i < nr; i++)
4991                 dsize += btrfs_item_size_nr(leaf, slot + i);
4992
4993         nritems = btrfs_header_nritems(leaf);
4994
4995         if (slot + nr != nritems) {
4996                 int data_end = leaf_data_end(fs_info, leaf);
4997
4998                 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4999                               data_end + dsize,
5000                               BTRFS_LEAF_DATA_OFFSET + data_end,
5001                               last_off - data_end);
5002
5003                 for (i = slot + nr; i < nritems; i++) {
5004                         u32 ioff;
5005
5006                         item = btrfs_item_nr(i);
5007                         ioff = btrfs_token_item_offset(leaf, item, &token);
5008                         btrfs_set_token_item_offset(leaf, item,
5009                                                     ioff + dsize, &token);
5010                 }
5011
5012                 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
5013                               btrfs_item_nr_offset(slot + nr),
5014                               sizeof(struct btrfs_item) *
5015                               (nritems - slot - nr));
5016         }
5017         btrfs_set_header_nritems(leaf, nritems - nr);
5018         nritems -= nr;
5019
5020         /* delete the leaf if we've emptied it */
5021         if (nritems == 0) {
5022                 if (leaf == root->node) {
5023                         btrfs_set_header_level(leaf, 0);
5024                 } else {
5025                         btrfs_set_path_blocking(path);
5026                         clean_tree_block(fs_info, leaf);
5027                         btrfs_del_leaf(trans, root, path, leaf);
5028                 }
5029         } else {
5030                 int used = leaf_space_used(leaf, 0, nritems);
5031                 if (slot == 0) {
5032                         struct btrfs_disk_key disk_key;
5033
5034                         btrfs_item_key(leaf, &disk_key, 0);
5035                         fixup_low_keys(fs_info, path, &disk_key, 1);
5036                 }
5037
5038                 /* delete the leaf if it is mostly empty */
5039                 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
5040                         /* push_leaf_left fixes the path.
5041                          * make sure the path still points to our leaf
5042                          * for possible call to del_ptr below
5043                          */
5044                         slot = path->slots[1];
5045                         extent_buffer_get(leaf);
5046
5047                         btrfs_set_path_blocking(path);
5048                         wret = push_leaf_left(trans, root, path, 1, 1,
5049                                               1, (u32)-1);
5050                         if (wret < 0 && wret != -ENOSPC)
5051                                 ret = wret;
5052
5053                         if (path->nodes[0] == leaf &&
5054                             btrfs_header_nritems(leaf)) {
5055                                 wret = push_leaf_right(trans, root, path, 1,
5056                                                        1, 1, 0);
5057                                 if (wret < 0 && wret != -ENOSPC)
5058                                         ret = wret;
5059                         }
5060
5061                         if (btrfs_header_nritems(leaf) == 0) {
5062                                 path->slots[1] = slot;
5063                                 btrfs_del_leaf(trans, root, path, leaf);
5064                                 free_extent_buffer(leaf);
5065                                 ret = 0;
5066                         } else {
5067                                 /* if we're still in the path, make sure
5068                                  * we're dirty.  Otherwise, one of the
5069                                  * push_leaf functions must have already
5070                                  * dirtied this buffer
5071                                  */
5072                                 if (path->nodes[0] == leaf)
5073                                         btrfs_mark_buffer_dirty(leaf);
5074                                 free_extent_buffer(leaf);
5075                         }
5076                 } else {
5077                         btrfs_mark_buffer_dirty(leaf);
5078                 }
5079         }
5080         return ret;
5081 }
5082
5083 /*
5084  * search the tree again to find a leaf with lesser keys
5085  * returns 0 if it found something or 1 if there are no lesser leaves.
5086  * returns < 0 on io errors.
5087  *
5088  * This may release the path, and so you may lose any locks held at the
5089  * time you call it.
5090  */
5091 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
5092 {
5093         struct btrfs_key key;
5094         struct btrfs_disk_key found_key;
5095         int ret;
5096
5097         btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
5098
5099         if (key.offset > 0) {
5100                 key.offset--;
5101         } else if (key.type > 0) {
5102                 key.type--;
5103                 key.offset = (u64)-1;
5104         } else if (key.objectid > 0) {
5105                 key.objectid--;
5106                 key.type = (u8)-1;
5107                 key.offset = (u64)-1;
5108         } else {
5109                 return 1;
5110         }
5111
5112         btrfs_release_path(path);
5113         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5114         if (ret < 0)
5115                 return ret;
5116         btrfs_item_key(path->nodes[0], &found_key, 0);
5117         ret = comp_keys(&found_key, &key);
5118         /*
5119          * We might have had an item with the previous key in the tree right
5120          * before we released our path. And after we released our path, that
5121          * item might have been pushed to the first slot (0) of the leaf we
5122          * were holding due to a tree balance. Alternatively, an item with the
5123          * previous key can exist as the only element of a leaf (big fat item).
5124          * Therefore account for these 2 cases, so that our callers (like
5125          * btrfs_previous_item) don't miss an existing item with a key matching
5126          * the previous key we computed above.
5127          */
5128         if (ret <= 0)
5129                 return 0;
5130         return 1;
5131 }
5132
5133 /*
5134  * A helper function to walk down the tree starting at min_key, and looking
5135  * for nodes or leaves that are have a minimum transaction id.
5136  * This is used by the btree defrag code, and tree logging
5137  *
5138  * This does not cow, but it does stuff the starting key it finds back
5139  * into min_key, so you can call btrfs_search_slot with cow=1 on the
5140  * key and get a writable path.
5141  *
5142  * This does lock as it descends, and path->keep_locks should be set
5143  * to 1 by the caller.
5144  *
5145  * This honors path->lowest_level to prevent descent past a given level
5146  * of the tree.
5147  *
5148  * min_trans indicates the oldest transaction that you are interested
5149  * in walking through.  Any nodes or leaves older than min_trans are
5150  * skipped over (without reading them).
5151  *
5152  * returns zero if something useful was found, < 0 on error and 1 if there
5153  * was nothing in the tree that matched the search criteria.
5154  */
5155 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
5156                          struct btrfs_path *path,
5157                          u64 min_trans)
5158 {
5159         struct btrfs_fs_info *fs_info = root->fs_info;
5160         struct extent_buffer *cur;
5161         struct btrfs_key found_key;
5162         int slot;
5163         int sret;
5164         u32 nritems;
5165         int level;
5166         int ret = 1;
5167         int keep_locks = path->keep_locks;
5168
5169         path->keep_locks = 1;
5170 again:
5171         cur = btrfs_read_lock_root_node(root);
5172         level = btrfs_header_level(cur);
5173         WARN_ON(path->nodes[level]);
5174         path->nodes[level] = cur;
5175         path->locks[level] = BTRFS_READ_LOCK;
5176
5177         if (btrfs_header_generation(cur) < min_trans) {
5178                 ret = 1;
5179                 goto out;
5180         }
5181         while (1) {
5182                 nritems = btrfs_header_nritems(cur);
5183                 level = btrfs_header_level(cur);
5184                 sret = bin_search(cur, min_key, level, &slot);
5185
5186                 /* at the lowest level, we're done, setup the path and exit */
5187                 if (level == path->lowest_level) {
5188                         if (slot >= nritems)
5189                                 goto find_next_key;
5190                         ret = 0;
5191                         path->slots[level] = slot;
5192                         btrfs_item_key_to_cpu(cur, &found_key, slot);
5193                         goto out;
5194                 }
5195                 if (sret && slot > 0)
5196                         slot--;
5197                 /*
5198                  * check this node pointer against the min_trans parameters.
5199                  * If it is too old, old, skip to the next one.
5200                  */
5201                 while (slot < nritems) {
5202                         u64 gen;
5203
5204                         gen = btrfs_node_ptr_generation(cur, slot);
5205                         if (gen < min_trans) {
5206                                 slot++;
5207                                 continue;
5208                         }
5209                         break;
5210                 }
5211 find_next_key:
5212                 /*
5213                  * we didn't find a candidate key in this node, walk forward
5214                  * and find another one
5215                  */
5216                 if (slot >= nritems) {
5217                         path->slots[level] = slot;
5218                         btrfs_set_path_blocking(path);
5219                         sret = btrfs_find_next_key(root, path, min_key, level,
5220                                                   min_trans);
5221                         if (sret == 0) {
5222                                 btrfs_release_path(path);
5223                                 goto again;
5224                         } else {
5225                                 goto out;
5226                         }
5227                 }
5228                 /* save our key for returning back */
5229                 btrfs_node_key_to_cpu(cur, &found_key, slot);
5230                 path->slots[level] = slot;
5231                 if (level == path->lowest_level) {
5232                         ret = 0;
5233                         goto out;
5234                 }
5235                 btrfs_set_path_blocking(path);
5236                 cur = read_node_slot(fs_info, cur, slot);
5237                 if (IS_ERR(cur)) {
5238                         ret = PTR_ERR(cur);
5239                         goto out;
5240                 }
5241
5242                 btrfs_tree_read_lock(cur);
5243
5244                 path->locks[level - 1] = BTRFS_READ_LOCK;
5245                 path->nodes[level - 1] = cur;
5246                 unlock_up(path, level, 1, 0, NULL);
5247                 btrfs_clear_path_blocking(path, NULL, 0);
5248         }
5249 out:
5250         path->keep_locks = keep_locks;
5251         if (ret == 0) {
5252                 btrfs_unlock_up_safe(path, path->lowest_level + 1);
5253                 btrfs_set_path_blocking(path);
5254                 memcpy(min_key, &found_key, sizeof(found_key));
5255         }
5256         return ret;
5257 }
5258
5259 static int tree_move_down(struct btrfs_fs_info *fs_info,
5260                            struct btrfs_path *path,
5261                            int *level)
5262 {
5263         struct extent_buffer *eb;
5264
5265         BUG_ON(*level == 0);
5266         eb = read_node_slot(fs_info, path->nodes[*level], path->slots[*level]);
5267         if (IS_ERR(eb))
5268                 return PTR_ERR(eb);
5269
5270         path->nodes[*level - 1] = eb;
5271         path->slots[*level - 1] = 0;
5272         (*level)--;
5273         return 0;
5274 }
5275
5276 static int tree_move_next_or_upnext(struct btrfs_path *path,
5277                                     int *level, int root_level)
5278 {
5279         int ret = 0;
5280         int nritems;
5281         nritems = btrfs_header_nritems(path->nodes[*level]);
5282
5283         path->slots[*level]++;
5284
5285         while (path->slots[*level] >= nritems) {
5286                 if (*level == root_level)
5287                         return -1;
5288
5289                 /* move upnext */
5290                 path->slots[*level] = 0;
5291                 free_extent_buffer(path->nodes[*level]);
5292                 path->nodes[*level] = NULL;
5293                 (*level)++;
5294                 path->slots[*level]++;
5295
5296                 nritems = btrfs_header_nritems(path->nodes[*level]);
5297                 ret = 1;
5298         }
5299         return ret;
5300 }
5301
5302 /*
5303  * Returns 1 if it had to move up and next. 0 is returned if it moved only next
5304  * or down.
5305  */
5306 static int tree_advance(struct btrfs_fs_info *fs_info,
5307                         struct btrfs_path *path,
5308                         int *level, int root_level,
5309                         int allow_down,
5310                         struct btrfs_key *key)
5311 {
5312         int ret;
5313
5314         if (*level == 0 || !allow_down) {
5315                 ret = tree_move_next_or_upnext(path, level, root_level);
5316         } else {
5317                 ret = tree_move_down(fs_info, path, level);
5318         }
5319         if (ret >= 0) {
5320                 if (*level == 0)
5321                         btrfs_item_key_to_cpu(path->nodes[*level], key,
5322                                         path->slots[*level]);
5323                 else
5324                         btrfs_node_key_to_cpu(path->nodes[*level], key,
5325                                         path->slots[*level]);
5326         }
5327         return ret;
5328 }
5329
5330 static int tree_compare_item(struct btrfs_path *left_path,
5331                              struct btrfs_path *right_path,
5332                              char *tmp_buf)
5333 {
5334         int cmp;
5335         int len1, len2;
5336         unsigned long off1, off2;
5337
5338         len1 = btrfs_item_size_nr(left_path->nodes[0], left_path->slots[0]);
5339         len2 = btrfs_item_size_nr(right_path->nodes[0], right_path->slots[0]);
5340         if (len1 != len2)
5341                 return 1;
5342
5343         off1 = btrfs_item_ptr_offset(left_path->nodes[0], left_path->slots[0]);
5344         off2 = btrfs_item_ptr_offset(right_path->nodes[0],
5345                                 right_path->slots[0]);
5346
5347         read_extent_buffer(left_path->nodes[0], tmp_buf, off1, len1);
5348
5349         cmp = memcmp_extent_buffer(right_path->nodes[0], tmp_buf, off2, len1);
5350         if (cmp)
5351                 return 1;
5352         return 0;
5353 }
5354
5355 #define ADVANCE 1
5356 #define ADVANCE_ONLY_NEXT -1
5357
5358 /*
5359  * This function compares two trees and calls the provided callback for
5360  * every changed/new/deleted item it finds.
5361  * If shared tree blocks are encountered, whole subtrees are skipped, making
5362  * the compare pretty fast on snapshotted subvolumes.
5363  *
5364  * This currently works on commit roots only. As commit roots are read only,
5365  * we don't do any locking. The commit roots are protected with transactions.
5366  * Transactions are ended and rejoined when a commit is tried in between.
5367  *
5368  * This function checks for modifications done to the trees while comparing.
5369  * If it detects a change, it aborts immediately.
5370  */
5371 int btrfs_compare_trees(struct btrfs_root *left_root,
5372                         struct btrfs_root *right_root,
5373                         btrfs_changed_cb_t changed_cb, void *ctx)
5374 {
5375         struct btrfs_fs_info *fs_info = left_root->fs_info;
5376         int ret;
5377         int cmp;
5378         struct btrfs_path *left_path = NULL;
5379         struct btrfs_path *right_path = NULL;
5380         struct btrfs_key left_key;
5381         struct btrfs_key right_key;
5382         char *tmp_buf = NULL;
5383         int left_root_level;
5384         int right_root_level;
5385         int left_level;
5386         int right_level;
5387         int left_end_reached;
5388         int right_end_reached;
5389         int advance_left;
5390         int advance_right;
5391         u64 left_blockptr;
5392         u64 right_blockptr;
5393         u64 left_gen;
5394         u64 right_gen;
5395
5396         left_path = btrfs_alloc_path();
5397         if (!left_path) {
5398                 ret = -ENOMEM;
5399                 goto out;
5400         }
5401         right_path = btrfs_alloc_path();
5402         if (!right_path) {
5403                 ret = -ENOMEM;
5404                 goto out;
5405         }
5406
5407         tmp_buf = kvmalloc(fs_info->nodesize, GFP_KERNEL);
5408         if (!tmp_buf) {
5409                 ret = -ENOMEM;
5410                 goto out;
5411         }
5412
5413         left_path->search_commit_root = 1;
5414         left_path->skip_locking = 1;
5415         right_path->search_commit_root = 1;
5416         right_path->skip_locking = 1;
5417
5418         /*
5419          * Strategy: Go to the first items of both trees. Then do
5420          *
5421          * If both trees are at level 0
5422          *   Compare keys of current items
5423          *     If left < right treat left item as new, advance left tree
5424          *       and repeat
5425          *     If left > right treat right item as deleted, advance right tree
5426          *       and repeat
5427          *     If left == right do deep compare of items, treat as changed if
5428          *       needed, advance both trees and repeat
5429          * If both trees are at the same level but not at level 0
5430          *   Compare keys of current nodes/leafs
5431          *     If left < right advance left tree and repeat
5432          *     If left > right advance right tree and repeat
5433          *     If left == right compare blockptrs of the next nodes/leafs
5434          *       If they match advance both trees but stay at the same level
5435          *         and repeat
5436          *       If they don't match advance both trees while allowing to go
5437          *         deeper and repeat
5438          * If tree levels are different
5439          *   Advance the tree that needs it and repeat
5440          *
5441          * Advancing a tree means:
5442          *   If we are at level 0, try to go to the next slot. If that's not
5443          *   possible, go one level up and repeat. Stop when we found a level
5444          *   where we could go to the next slot. We may at this point be on a
5445          *   node or a leaf.
5446          *
5447          *   If we are not at level 0 and not on shared tree blocks, go one
5448          *   level deeper.
5449          *
5450          *   If we are not at level 0 and on shared tree blocks, go one slot to
5451          *   the right if possible or go up and right.
5452          */
5453
5454         down_read(&fs_info->commit_root_sem);
5455         left_level = btrfs_header_level(left_root->commit_root);
5456         left_root_level = left_level;
5457         left_path->nodes[left_level] =
5458                         btrfs_clone_extent_buffer(left_root->commit_root);
5459         if (!left_path->nodes[left_level]) {
5460                 up_read(&fs_info->commit_root_sem);
5461                 ret = -ENOMEM;
5462                 goto out;
5463         }
5464         extent_buffer_get(left_path->nodes[left_level]);
5465
5466         right_level = btrfs_header_level(right_root->commit_root);
5467         right_root_level = right_level;
5468         right_path->nodes[right_level] =
5469                         btrfs_clone_extent_buffer(right_root->commit_root);
5470         if (!right_path->nodes[right_level]) {
5471                 up_read(&fs_info->commit_root_sem);
5472                 ret = -ENOMEM;
5473                 goto out;
5474         }
5475         extent_buffer_get(right_path->nodes[right_level]);
5476         up_read(&fs_info->commit_root_sem);
5477
5478         if (left_level == 0)
5479                 btrfs_item_key_to_cpu(left_path->nodes[left_level],
5480                                 &left_key, left_path->slots[left_level]);
5481         else
5482                 btrfs_node_key_to_cpu(left_path->nodes[left_level],
5483                                 &left_key, left_path->slots[left_level]);
5484         if (right_level == 0)
5485                 btrfs_item_key_to_cpu(right_path->nodes[right_level],
5486                                 &right_key, right_path->slots[right_level]);
5487         else
5488                 btrfs_node_key_to_cpu(right_path->nodes[right_level],
5489                                 &right_key, right_path->slots[right_level]);
5490
5491         left_end_reached = right_end_reached = 0;
5492         advance_left = advance_right = 0;
5493
5494         while (1) {
5495                 if (advance_left && !left_end_reached) {
5496                         ret = tree_advance(fs_info, left_path, &left_level,
5497                                         left_root_level,
5498                                         advance_left != ADVANCE_ONLY_NEXT,
5499                                         &left_key);
5500                         if (ret == -1)
5501                                 left_end_reached = ADVANCE;
5502                         else if (ret < 0)
5503                                 goto out;
5504                         advance_left = 0;
5505                 }
5506                 if (advance_right && !right_end_reached) {
5507                         ret = tree_advance(fs_info, right_path, &right_level,
5508                                         right_root_level,
5509                                         advance_right != ADVANCE_ONLY_NEXT,
5510                                         &right_key);
5511                         if (ret == -1)
5512                                 right_end_reached = ADVANCE;
5513                         else if (ret < 0)
5514                                 goto out;
5515                         advance_right = 0;
5516                 }
5517
5518                 if (left_end_reached && right_end_reached) {
5519                         ret = 0;
5520                         goto out;
5521                 } else if (left_end_reached) {
5522                         if (right_level == 0) {
5523                                 ret = changed_cb(left_root, right_root,
5524                                                 left_path, right_path,
5525                                                 &right_key,
5526                                                 BTRFS_COMPARE_TREE_DELETED,
5527                                                 ctx);
5528                                 if (ret < 0)
5529                                         goto out;
5530                         }
5531                         advance_right = ADVANCE;
5532                         continue;
5533                 } else if (right_end_reached) {
5534                         if (left_level == 0) {
5535                                 ret = changed_cb(left_root, right_root,
5536                                                 left_path, right_path,
5537                                                 &left_key,
5538                                                 BTRFS_COMPARE_TREE_NEW,
5539                                                 ctx);
5540                                 if (ret < 0)
5541                                         goto out;
5542                         }
5543                         advance_left = ADVANCE;
5544                         continue;
5545                 }
5546
5547                 if (left_level == 0 && right_level == 0) {
5548                         cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
5549                         if (cmp < 0) {
5550                                 ret = changed_cb(left_root, right_root,
5551                                                 left_path, right_path,
5552                                                 &left_key,
5553                                                 BTRFS_COMPARE_TREE_NEW,
5554                                                 ctx);
5555                                 if (ret < 0)
5556                                         goto out;
5557                                 advance_left = ADVANCE;
5558                         } else if (cmp > 0) {
5559                                 ret = changed_cb(left_root, right_root,
5560                                                 left_path, right_path,
5561                                                 &right_key,
5562                                                 BTRFS_COMPARE_TREE_DELETED,
5563                                                 ctx);
5564                                 if (ret < 0)
5565                                         goto out;
5566                                 advance_right = ADVANCE;
5567                         } else {
5568                                 enum btrfs_compare_tree_result result;
5569
5570                                 WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
5571                                 ret = tree_compare_item(left_path, right_path,
5572                                                         tmp_buf);
5573                                 if (ret)
5574                                         result = BTRFS_COMPARE_TREE_CHANGED;
5575                                 else
5576                                         result = BTRFS_COMPARE_TREE_SAME;
5577                                 ret = changed_cb(left_root, right_root,
5578                                                  left_path, right_path,
5579                                                  &left_key, result, ctx);
5580                                 if (ret < 0)
5581                                         goto out;
5582                                 advance_left = ADVANCE;
5583                                 advance_right = ADVANCE;
5584                         }
5585                 } else if (left_level == right_level) {
5586                         cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
5587                         if (cmp < 0) {
5588                                 advance_left = ADVANCE;
5589                         } else if (cmp > 0) {
5590                                 advance_right = ADVANCE;
5591                         } else {
5592                                 left_blockptr = btrfs_node_blockptr(
5593                                                 left_path->nodes[left_level],
5594                                                 left_path->slots[left_level]);
5595                                 right_blockptr = btrfs_node_blockptr(
5596                                                 right_path->nodes[right_level],
5597                                                 right_path->slots[right_level]);
5598                                 left_gen = btrfs_node_ptr_generation(
5599                                                 left_path->nodes[left_level],
5600                                                 left_path->slots[left_level]);
5601                                 right_gen = btrfs_node_ptr_generation(
5602                                                 right_path->nodes[right_level],
5603                                                 right_path->slots[right_level]);
5604                                 if (left_blockptr == right_blockptr &&
5605                                     left_gen == right_gen) {
5606                                         /*
5607                                          * As we're on a shared block, don't
5608                                          * allow to go deeper.
5609                                          */
5610                                         advance_left = ADVANCE_ONLY_NEXT;
5611                                         advance_right = ADVANCE_ONLY_NEXT;
5612                                 } else {
5613                                         advance_left = ADVANCE;
5614                                         advance_right = ADVANCE;
5615                                 }
5616                         }
5617                 } else if (left_level < right_level) {
5618                         advance_right = ADVANCE;
5619                 } else {
5620                         advance_left = ADVANCE;
5621                 }
5622         }
5623
5624 out:
5625         btrfs_free_path(left_path);
5626         btrfs_free_path(right_path);
5627         kvfree(tmp_buf);
5628         return ret;
5629 }
5630
5631 /*
5632  * this is similar to btrfs_next_leaf, but does not try to preserve
5633  * and fixup the path.  It looks for and returns the next key in the
5634  * tree based on the current path and the min_trans parameters.
5635  *
5636  * 0 is returned if another key is found, < 0 if there are any errors
5637  * and 1 is returned if there are no higher keys in the tree
5638  *
5639  * path->keep_locks should be set to 1 on the search made before
5640  * calling this function.
5641  */
5642 int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
5643                         struct btrfs_key *key, int level, u64 min_trans)
5644 {
5645         int slot;
5646         struct extent_buffer *c;
5647
5648         WARN_ON(!path->keep_locks);
5649         while (level < BTRFS_MAX_LEVEL) {
5650                 if (!path->nodes[level])
5651                         return 1;
5652
5653                 slot = path->slots[level] + 1;
5654                 c = path->nodes[level];
5655 next:
5656                 if (slot >= btrfs_header_nritems(c)) {
5657                         int ret;
5658                         int orig_lowest;
5659                         struct btrfs_key cur_key;
5660                         if (level + 1 >= BTRFS_MAX_LEVEL ||
5661                             !path->nodes[level + 1])
5662                                 return 1;
5663
5664                         if (path->locks[level + 1]) {
5665                                 level++;
5666                                 continue;
5667                         }
5668
5669                         slot = btrfs_header_nritems(c) - 1;
5670                         if (level == 0)
5671                                 btrfs_item_key_to_cpu(c, &cur_key, slot);
5672                         else
5673                                 btrfs_node_key_to_cpu(c, &cur_key, slot);
5674
5675                         orig_lowest = path->lowest_level;
5676                         btrfs_release_path(path);
5677                         path->lowest_level = level;
5678                         ret = btrfs_search_slot(NULL, root, &cur_key, path,
5679                                                 0, 0);
5680                         path->lowest_level = orig_lowest;
5681                         if (ret < 0)
5682                                 return ret;
5683
5684                         c = path->nodes[level];
5685                         slot = path->slots[level];
5686                         if (ret == 0)
5687                                 slot++;
5688                         goto next;
5689                 }
5690
5691                 if (level == 0)
5692                         btrfs_item_key_to_cpu(c, key, slot);
5693                 else {
5694                         u64 gen = btrfs_node_ptr_generation(c, slot);
5695
5696                         if (gen < min_trans) {
5697                                 slot++;
5698                                 goto next;
5699                         }
5700                         btrfs_node_key_to_cpu(c, key, slot);
5701                 }
5702                 return 0;
5703         }
5704         return 1;
5705 }
5706
5707 /*
5708  * search the tree again to find a leaf with greater keys
5709  * returns 0 if it found something or 1 if there are no greater leaves.
5710  * returns < 0 on io errors.
5711  */
5712 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
5713 {
5714         return btrfs_next_old_leaf(root, path, 0);
5715 }
5716
5717 int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
5718                         u64 time_seq)
5719 {
5720         int slot;
5721         int level;
5722         struct extent_buffer *c;
5723         struct extent_buffer *next;
5724         struct btrfs_key key;
5725         u32 nritems;
5726         int ret;
5727         int old_spinning = path->leave_spinning;
5728         int next_rw_lock = 0;
5729
5730         nritems = btrfs_header_nritems(path->nodes[0]);
5731         if (nritems == 0)
5732                 return 1;
5733
5734         btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5735 again:
5736         level = 1;
5737         next = NULL;
5738         next_rw_lock = 0;
5739         btrfs_release_path(path);
5740
5741         path->keep_locks = 1;
5742         path->leave_spinning = 1;
5743
5744         if (time_seq)
5745                 ret = btrfs_search_old_slot(root, &key, path, time_seq);
5746         else
5747                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5748         path->keep_locks = 0;
5749
5750         if (ret < 0)
5751                 return ret;
5752
5753         nritems = btrfs_header_nritems(path->nodes[0]);
5754         /*
5755          * by releasing the path above we dropped all our locks.  A balance
5756          * could have added more items next to the key that used to be
5757          * at the very end of the block.  So, check again here and
5758          * advance the path if there are now more items available.
5759          */
5760         if (nritems > 0 && path->slots[0] < nritems - 1) {
5761                 if (ret == 0)
5762                         path->slots[0]++;
5763                 ret = 0;
5764                 goto done;
5765         }
5766         /*
5767          * So the above check misses one case:
5768          * - after releasing the path above, someone has removed the item that
5769          *   used to be at the very end of the block, and balance between leafs
5770          *   gets another one with bigger key.offset to replace it.
5771          *
5772          * This one should be returned as well, or we can get leaf corruption
5773          * later(esp. in __btrfs_drop_extents()).
5774          *
5775          * And a bit more explanation about this check,
5776          * with ret > 0, the key isn't found, the path points to the slot
5777          * where it should be inserted, so the path->slots[0] item must be the
5778          * bigger one.
5779          */
5780         if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
5781                 ret = 0;
5782                 goto done;
5783         }
5784
5785         while (level < BTRFS_MAX_LEVEL) {
5786                 if (!path->nodes[level]) {
5787                         ret = 1;
5788                         goto done;
5789                 }
5790
5791                 slot = path->slots[level] + 1;
5792                 c = path->nodes[level];
5793                 if (slot >= btrfs_header_nritems(c)) {
5794                         level++;
5795                         if (level == BTRFS_MAX_LEVEL) {
5796                                 ret = 1;
5797                                 goto done;
5798                         }
5799                         continue;
5800                 }
5801
5802                 if (next) {
5803                         btrfs_tree_unlock_rw(next, next_rw_lock);
5804                         free_extent_buffer(next);
5805                 }
5806
5807                 next = c;
5808                 next_rw_lock = path->locks[level];
5809                 ret = read_block_for_search(root, path, &next, level,
5810                                             slot, &key);
5811                 if (ret == -EAGAIN)
5812                         goto again;
5813
5814                 if (ret < 0) {
5815                         btrfs_release_path(path);
5816                         goto done;
5817                 }
5818
5819                 if (!path->skip_locking) {
5820                         ret = btrfs_try_tree_read_lock(next);
5821                         if (!ret && time_seq) {
5822                                 /*
5823                                  * If we don't get the lock, we may be racing
5824                                  * with push_leaf_left, holding that lock while
5825                                  * itself waiting for the leaf we've currently
5826                                  * locked. To solve this situation, we give up
5827                                  * on our lock and cycle.
5828                                  */
5829                                 free_extent_buffer(next);
5830                                 btrfs_release_path(path);
5831                                 cond_resched();
5832                                 goto again;
5833                         }
5834                         if (!ret) {
5835                                 btrfs_set_path_blocking(path);
5836                                 btrfs_tree_read_lock(next);
5837                                 btrfs_clear_path_blocking(path, next,
5838                                                           BTRFS_READ_LOCK);
5839                         }
5840                         next_rw_lock = BTRFS_READ_LOCK;
5841                 }
5842                 break;
5843         }
5844         path->slots[level] = slot;
5845         while (1) {
5846                 level--;
5847                 c = path->nodes[level];
5848                 if (path->locks[level])
5849                         btrfs_tree_unlock_rw(c, path->locks[level]);
5850
5851                 free_extent_buffer(c);
5852                 path->nodes[level] = next;
5853                 path->slots[level] = 0;
5854                 if (!path->skip_locking)
5855                         path->locks[level] = next_rw_lock;
5856                 if (!level)
5857                         break;
5858
5859                 ret = read_block_for_search(root, path, &next, level,
5860                                             0, &key);
5861                 if (ret == -EAGAIN)
5862                         goto again;
5863
5864                 if (ret < 0) {
5865                         btrfs_release_path(path);
5866                         goto done;
5867                 }
5868
5869                 if (!path->skip_locking) {
5870                         ret = btrfs_try_tree_read_lock(next);
5871                         if (!ret) {
5872                                 btrfs_set_path_blocking(path);
5873                                 btrfs_tree_read_lock(next);
5874                                 btrfs_clear_path_blocking(path, next,
5875                                                           BTRFS_READ_LOCK);
5876                         }
5877                         next_rw_lock = BTRFS_READ_LOCK;
5878                 }
5879         }
5880         ret = 0;
5881 done:
5882         unlock_up(path, 0, 1, 0, NULL);
5883         path->leave_spinning = old_spinning;
5884         if (!old_spinning)
5885                 btrfs_set_path_blocking(path);
5886
5887         return ret;
5888 }
5889
5890 /*
5891  * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5892  * searching until it gets past min_objectid or finds an item of 'type'
5893  *
5894  * returns 0 if something is found, 1 if nothing was found and < 0 on error
5895  */
5896 int btrfs_previous_item(struct btrfs_root *root,
5897                         struct btrfs_path *path, u64 min_objectid,
5898                         int type)
5899 {
5900         struct btrfs_key found_key;
5901         struct extent_buffer *leaf;
5902         u32 nritems;
5903         int ret;
5904
5905         while (1) {
5906                 if (path->slots[0] == 0) {
5907                         btrfs_set_path_blocking(path);
5908                         ret = btrfs_prev_leaf(root, path);
5909                         if (ret != 0)
5910                                 return ret;
5911                 } else {
5912                         path->slots[0]--;
5913                 }
5914                 leaf = path->nodes[0];
5915                 nritems = btrfs_header_nritems(leaf);
5916                 if (nritems == 0)
5917                         return 1;
5918                 if (path->slots[0] == nritems)
5919                         path->slots[0]--;
5920
5921                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5922                 if (found_key.objectid < min_objectid)
5923                         break;
5924                 if (found_key.type == type)
5925                         return 0;
5926                 if (found_key.objectid == min_objectid &&
5927                     found_key.type < type)
5928                         break;
5929         }
5930         return 1;
5931 }
5932
5933 /*
5934  * search in extent tree to find a previous Metadata/Data extent item with
5935  * min objecitd.
5936  *
5937  * returns 0 if something is found, 1 if nothing was found and < 0 on error
5938  */
5939 int btrfs_previous_extent_item(struct btrfs_root *root,
5940                         struct btrfs_path *path, u64 min_objectid)
5941 {
5942         struct btrfs_key found_key;
5943         struct extent_buffer *leaf;
5944         u32 nritems;
5945         int ret;
5946
5947         while (1) {
5948                 if (path->slots[0] == 0) {
5949                         btrfs_set_path_blocking(path);
5950                         ret = btrfs_prev_leaf(root, path);
5951                         if (ret != 0)
5952                                 return ret;
5953                 } else {
5954                         path->slots[0]--;
5955                 }
5956                 leaf = path->nodes[0];
5957                 nritems = btrfs_header_nritems(leaf);
5958                 if (nritems == 0)
5959                         return 1;
5960                 if (path->slots[0] == nritems)
5961                         path->slots[0]--;
5962
5963                 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5964                 if (found_key.objectid < min_objectid)
5965                         break;
5966                 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5967                     found_key.type == BTRFS_METADATA_ITEM_KEY)
5968                         return 0;
5969                 if (found_key.objectid == min_objectid &&
5970                     found_key.type < BTRFS_EXTENT_ITEM_KEY)
5971                         break;
5972         }
5973         return 1;
5974 }