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