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