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