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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_trans_handle *trans, struct btrfs_root *root,
41                     struct btrfs_path *path, int level, int slot,
42                     int tree_mod_log);
43 static void tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
44                                  struct extent_buffer *eb);
45 struct extent_buffer *read_old_tree_block(struct btrfs_root *root, u64 bytenr,
46                                           u32 blocksize, u64 parent_transid,
47                                           u64 time_seq);
48 struct extent_buffer *btrfs_find_old_tree_block(struct btrfs_root *root,
49                                                 u64 bytenr, u32 blocksize,
50                                                 u64 time_seq);
51
52 struct btrfs_path *btrfs_alloc_path(void)
53 {
54         struct btrfs_path *path;
55         path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
56         return path;
57 }
58
59 /*
60  * set all locked nodes in the path to blocking locks.  This should
61  * be done before scheduling
62  */
63 noinline void btrfs_set_path_blocking(struct btrfs_path *p)
64 {
65         int i;
66         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
67                 if (!p->nodes[i] || !p->locks[i])
68                         continue;
69                 btrfs_set_lock_blocking_rw(p->nodes[i], p->locks[i]);
70                 if (p->locks[i] == BTRFS_READ_LOCK)
71                         p->locks[i] = BTRFS_READ_LOCK_BLOCKING;
72                 else if (p->locks[i] == BTRFS_WRITE_LOCK)
73                         p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING;
74         }
75 }
76
77 /*
78  * reset all the locked nodes in the patch to spinning locks.
79  *
80  * held is used to keep lockdep happy, when lockdep is enabled
81  * we set held to a blocking lock before we go around and
82  * retake all the spinlocks in the path.  You can safely use NULL
83  * for held
84  */
85 noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
86                                         struct extent_buffer *held, int held_rw)
87 {
88         int i;
89
90 #ifdef CONFIG_DEBUG_LOCK_ALLOC
91         /* lockdep really cares that we take all of these spinlocks
92          * in the right order.  If any of the locks in the path are not
93          * currently blocking, it is going to complain.  So, make really
94          * really sure by forcing the path to blocking before we clear
95          * the path blocking.
96          */
97         if (held) {
98                 btrfs_set_lock_blocking_rw(held, held_rw);
99                 if (held_rw == BTRFS_WRITE_LOCK)
100                         held_rw = BTRFS_WRITE_LOCK_BLOCKING;
101                 else if (held_rw == BTRFS_READ_LOCK)
102                         held_rw = BTRFS_READ_LOCK_BLOCKING;
103         }
104         btrfs_set_path_blocking(p);
105 #endif
106
107         for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
108                 if (p->nodes[i] && p->locks[i]) {
109                         btrfs_clear_lock_blocking_rw(p->nodes[i], p->locks[i]);
110                         if (p->locks[i] == BTRFS_WRITE_LOCK_BLOCKING)
111                                 p->locks[i] = BTRFS_WRITE_LOCK;
112                         else if (p->locks[i] == BTRFS_READ_LOCK_BLOCKING)
113                                 p->locks[i] = BTRFS_READ_LOCK;
114                 }
115         }
116
117 #ifdef CONFIG_DEBUG_LOCK_ALLOC
118         if (held)
119                 btrfs_clear_lock_blocking_rw(held, held_rw);
120 #endif
121 }
122
123 /* this also releases the path */
124 void btrfs_free_path(struct btrfs_path *p)
125 {
126         if (!p)
127                 return;
128         btrfs_release_path(p);
129         kmem_cache_free(btrfs_path_cachep, p);
130 }
131
132 /*
133  * path release drops references on the extent buffers in the path
134  * and it drops any locks held by this path
135  *
136  * It is safe to call this on paths that no locks or extent buffers held.
137  */
138 noinline void btrfs_release_path(struct btrfs_path *p)
139 {
140         int i;
141
142         for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
143                 p->slots[i] = 0;
144                 if (!p->nodes[i])
145                         continue;
146                 if (p->locks[i]) {
147                         btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
148                         p->locks[i] = 0;
149                 }
150                 free_extent_buffer(p->nodes[i]);
151                 p->nodes[i] = NULL;
152         }
153 }
154
155 /*
156  * safely gets a reference on the root node of a tree.  A lock
157  * is not taken, so a concurrent writer may put a different node
158  * at the root of the tree.  See btrfs_lock_root_node for the
159  * looping required.
160  *
161  * The extent buffer returned by this has a reference taken, so
162  * it won't disappear.  It may stop being the root of the tree
163  * at any time because there are no locks held.
164  */
165 struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
166 {
167         struct extent_buffer *eb;
168
169         while (1) {
170                 rcu_read_lock();
171                 eb = rcu_dereference(root->node);
172
173                 /*
174                  * RCU really hurts here, we could free up the root node because
175                  * it was cow'ed but we may not get the new root node yet so do
176                  * the inc_not_zero dance and if it doesn't work then
177                  * synchronize_rcu and try again.
178                  */
179                 if (atomic_inc_not_zero(&eb->refs)) {
180                         rcu_read_unlock();
181                         break;
182                 }
183                 rcu_read_unlock();
184                 synchronize_rcu();
185         }
186         return eb;
187 }
188
189 /* loop around taking references on and locking the root node of the
190  * tree until you end up with a lock on the root.  A locked buffer
191  * is returned, with a reference held.
192  */
193 struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
194 {
195         struct extent_buffer *eb;
196
197         while (1) {
198                 eb = btrfs_root_node(root);
199                 btrfs_tree_lock(eb);
200                 if (eb == root->node)
201                         break;
202                 btrfs_tree_unlock(eb);
203                 free_extent_buffer(eb);
204         }
205         return eb;
206 }
207
208 /* loop around taking references on and locking the root node of the
209  * tree until you end up with a lock on the root.  A locked buffer
210  * is returned, with a reference held.
211  */
212 struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
213 {
214         struct extent_buffer *eb;
215
216         while (1) {
217                 eb = btrfs_root_node(root);
218                 btrfs_tree_read_lock(eb);
219                 if (eb == root->node)
220                         break;
221                 btrfs_tree_read_unlock(eb);
222                 free_extent_buffer(eb);
223         }
224         return eb;
225 }
226
227 /* cowonly root (everything not a reference counted cow subvolume), just get
228  * put onto a simple dirty list.  transaction.c walks this to make sure they
229  * get properly updated on disk.
230  */
231 static void add_root_to_dirty_list(struct btrfs_root *root)
232 {
233         spin_lock(&root->fs_info->trans_lock);
234         if (root->track_dirty && list_empty(&root->dirty_list)) {
235                 list_add(&root->dirty_list,
236                          &root->fs_info->dirty_cowonly_roots);
237         }
238         spin_unlock(&root->fs_info->trans_lock);
239 }
240
241 /*
242  * used by snapshot creation to make a copy of a root for a tree with
243  * a given objectid.  The buffer with the new root node is returned in
244  * cow_ret, and this func returns zero on success or a negative error code.
245  */
246 int btrfs_copy_root(struct btrfs_trans_handle *trans,
247                       struct btrfs_root *root,
248                       struct extent_buffer *buf,
249                       struct extent_buffer **cow_ret, u64 new_root_objectid)
250 {
251         struct extent_buffer *cow;
252         int ret = 0;
253         int level;
254         struct btrfs_disk_key disk_key;
255
256         WARN_ON(root->ref_cows && trans->transid !=
257                 root->fs_info->running_transaction->transid);
258         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
259
260         level = btrfs_header_level(buf);
261         if (level == 0)
262                 btrfs_item_key(buf, &disk_key, 0);
263         else
264                 btrfs_node_key(buf, &disk_key, 0);
265
266         cow = btrfs_alloc_free_block(trans, root, buf->len, 0,
267                                      new_root_objectid, &disk_key, level,
268                                      buf->start, 0);
269         if (IS_ERR(cow))
270                 return PTR_ERR(cow);
271
272         copy_extent_buffer(cow, buf, 0, 0, cow->len);
273         btrfs_set_header_bytenr(cow, cow->start);
274         btrfs_set_header_generation(cow, trans->transid);
275         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
276         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
277                                      BTRFS_HEADER_FLAG_RELOC);
278         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
279                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
280         else
281                 btrfs_set_header_owner(cow, new_root_objectid);
282
283         write_extent_buffer(cow, root->fs_info->fsid,
284                             (unsigned long)btrfs_header_fsid(cow),
285                             BTRFS_FSID_SIZE);
286
287         WARN_ON(btrfs_header_generation(buf) > trans->transid);
288         if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
289                 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
290         else
291                 ret = btrfs_inc_ref(trans, root, cow, 0, 1);
292
293         if (ret)
294                 return ret;
295
296         btrfs_mark_buffer_dirty(cow);
297         *cow_ret = cow;
298         return 0;
299 }
300
301 enum mod_log_op {
302         MOD_LOG_KEY_REPLACE,
303         MOD_LOG_KEY_ADD,
304         MOD_LOG_KEY_REMOVE,
305         MOD_LOG_KEY_REMOVE_WHILE_FREEING,
306         MOD_LOG_KEY_REMOVE_WHILE_MOVING,
307         MOD_LOG_MOVE_KEYS,
308         MOD_LOG_ROOT_REPLACE,
309 };
310
311 struct tree_mod_move {
312         int dst_slot;
313         int nr_items;
314 };
315
316 struct tree_mod_root {
317         u64 logical;
318         u8 level;
319 };
320
321 struct tree_mod_elem {
322         struct rb_node node;
323         u64 index;              /* shifted logical */
324         u64 seq;
325         enum mod_log_op op;
326
327         /* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
328         int slot;
329
330         /* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
331         u64 generation;
332
333         /* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
334         struct btrfs_disk_key key;
335         u64 blockptr;
336
337         /* this is used for op == MOD_LOG_MOVE_KEYS */
338         struct tree_mod_move move;
339
340         /* this is used for op == MOD_LOG_ROOT_REPLACE */
341         struct tree_mod_root old_root;
342 };
343
344 static inline void tree_mod_log_read_lock(struct btrfs_fs_info *fs_info)
345 {
346         read_lock(&fs_info->tree_mod_log_lock);
347 }
348
349 static inline void tree_mod_log_read_unlock(struct btrfs_fs_info *fs_info)
350 {
351         read_unlock(&fs_info->tree_mod_log_lock);
352 }
353
354 static inline void tree_mod_log_write_lock(struct btrfs_fs_info *fs_info)
355 {
356         write_lock(&fs_info->tree_mod_log_lock);
357 }
358
359 static inline void tree_mod_log_write_unlock(struct btrfs_fs_info *fs_info)
360 {
361         write_unlock(&fs_info->tree_mod_log_lock);
362 }
363
364 /*
365  * This adds a new blocker to the tree mod log's blocker list if the @elem
366  * passed does not already have a sequence number set. So when a caller expects
367  * to record tree modifications, it should ensure to set elem->seq to zero
368  * before calling btrfs_get_tree_mod_seq.
369  * Returns a fresh, unused tree log modification sequence number, even if no new
370  * blocker was added.
371  */
372 u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
373                            struct seq_list *elem)
374 {
375         u64 seq;
376
377         tree_mod_log_write_lock(fs_info);
378         spin_lock(&fs_info->tree_mod_seq_lock);
379         if (!elem->seq) {
380                 elem->seq = btrfs_inc_tree_mod_seq(fs_info);
381                 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
382         }
383         seq = btrfs_inc_tree_mod_seq(fs_info);
384         spin_unlock(&fs_info->tree_mod_seq_lock);
385         tree_mod_log_write_unlock(fs_info);
386
387         return seq;
388 }
389
390 void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
391                             struct seq_list *elem)
392 {
393         struct rb_root *tm_root;
394         struct rb_node *node;
395         struct rb_node *next;
396         struct seq_list *cur_elem;
397         struct tree_mod_elem *tm;
398         u64 min_seq = (u64)-1;
399         u64 seq_putting = elem->seq;
400
401         if (!seq_putting)
402                 return;
403
404         spin_lock(&fs_info->tree_mod_seq_lock);
405         list_del(&elem->list);
406         elem->seq = 0;
407
408         list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) {
409                 if (cur_elem->seq < min_seq) {
410                         if (seq_putting > cur_elem->seq) {
411                                 /*
412                                  * blocker with lower sequence number exists, we
413                                  * cannot remove anything from the log
414                                  */
415                                 spin_unlock(&fs_info->tree_mod_seq_lock);
416                                 return;
417                         }
418                         min_seq = cur_elem->seq;
419                 }
420         }
421         spin_unlock(&fs_info->tree_mod_seq_lock);
422
423         /*
424          * anything that's lower than the lowest existing (read: blocked)
425          * sequence number can be removed from the tree.
426          */
427         tree_mod_log_write_lock(fs_info);
428         tm_root = &fs_info->tree_mod_log;
429         for (node = rb_first(tm_root); node; node = next) {
430                 next = rb_next(node);
431                 tm = container_of(node, struct tree_mod_elem, node);
432                 if (tm->seq > min_seq)
433                         continue;
434                 rb_erase(node, tm_root);
435                 kfree(tm);
436         }
437         tree_mod_log_write_unlock(fs_info);
438 }
439
440 /*
441  * key order of the log:
442  *       index -> sequence
443  *
444  * the index is the shifted logical of the *new* root node for root replace
445  * operations, or the shifted logical of the affected block for all other
446  * operations.
447  */
448 static noinline int
449 __tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
450 {
451         struct rb_root *tm_root;
452         struct rb_node **new;
453         struct rb_node *parent = NULL;
454         struct tree_mod_elem *cur;
455
456         BUG_ON(!tm || !tm->seq);
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                         kfree(tm);
473                         return -EEXIST;
474                 }
475         }
476
477         rb_link_node(&tm->node, parent, new);
478         rb_insert_color(&tm->node, tm_root);
479         return 0;
480 }
481
482 /*
483  * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it
484  * returns zero with the tree_mod_log_lock acquired. The caller must hold
485  * this until all tree mod log insertions are recorded in the rb tree and then
486  * call tree_mod_log_write_unlock() to release.
487  */
488 static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
489                                     struct extent_buffer *eb) {
490         smp_mb();
491         if (list_empty(&(fs_info)->tree_mod_seq_list))
492                 return 1;
493         if (eb && btrfs_header_level(eb) == 0)
494                 return 1;
495
496         tree_mod_log_write_lock(fs_info);
497         if (list_empty(&fs_info->tree_mod_seq_list)) {
498                 /*
499                  * someone emptied the list while we were waiting for the lock.
500                  * we must not add to the list when no blocker exists.
501                  */
502                 tree_mod_log_write_unlock(fs_info);
503                 return 1;
504         }
505
506         return 0;
507 }
508
509 /*
510  * This allocates memory and gets a tree modification sequence number.
511  *
512  * Returns <0 on error.
513  * Returns >0 (the added sequence number) on success.
514  */
515 static inline int tree_mod_alloc(struct btrfs_fs_info *fs_info, gfp_t flags,
516                                  struct tree_mod_elem **tm_ret)
517 {
518         struct tree_mod_elem *tm;
519
520         /*
521          * once we switch from spin locks to something different, we should
522          * honor the flags parameter here.
523          */
524         tm = *tm_ret = kzalloc(sizeof(*tm), GFP_ATOMIC);
525         if (!tm)
526                 return -ENOMEM;
527
528         tm->seq = btrfs_inc_tree_mod_seq(fs_info);
529         return tm->seq;
530 }
531
532 static inline int
533 __tree_mod_log_insert_key(struct btrfs_fs_info *fs_info,
534                           struct extent_buffer *eb, int slot,
535                           enum mod_log_op op, gfp_t flags)
536 {
537         int ret;
538         struct tree_mod_elem *tm;
539
540         ret = tree_mod_alloc(fs_info, flags, &tm);
541         if (ret < 0)
542                 return ret;
543
544         tm->index = eb->start >> PAGE_CACHE_SHIFT;
545         if (op != MOD_LOG_KEY_ADD) {
546                 btrfs_node_key(eb, &tm->key, slot);
547                 tm->blockptr = btrfs_node_blockptr(eb, slot);
548         }
549         tm->op = op;
550         tm->slot = slot;
551         tm->generation = btrfs_node_ptr_generation(eb, slot);
552
553         return __tree_mod_log_insert(fs_info, tm);
554 }
555
556 static noinline int
557 tree_mod_log_insert_key_mask(struct btrfs_fs_info *fs_info,
558                              struct extent_buffer *eb, int slot,
559                              enum mod_log_op op, gfp_t flags)
560 {
561         int ret;
562
563         if (tree_mod_dont_log(fs_info, eb))
564                 return 0;
565
566         ret = __tree_mod_log_insert_key(fs_info, eb, slot, op, flags);
567
568         tree_mod_log_write_unlock(fs_info);
569         return ret;
570 }
571
572 static noinline int
573 tree_mod_log_insert_key(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
574                         int slot, enum mod_log_op op)
575 {
576         return tree_mod_log_insert_key_mask(fs_info, eb, slot, op, GFP_NOFS);
577 }
578
579 static noinline int
580 tree_mod_log_insert_key_locked(struct btrfs_fs_info *fs_info,
581                              struct extent_buffer *eb, int slot,
582                              enum mod_log_op op)
583 {
584         return __tree_mod_log_insert_key(fs_info, eb, slot, op, GFP_NOFS);
585 }
586
587 static noinline int
588 tree_mod_log_insert_move(struct btrfs_fs_info *fs_info,
589                          struct extent_buffer *eb, int dst_slot, int src_slot,
590                          int nr_items, gfp_t flags)
591 {
592         struct tree_mod_elem *tm;
593         int ret;
594         int i;
595
596         if (tree_mod_dont_log(fs_info, eb))
597                 return 0;
598
599         /*
600          * When we override something during the move, we log these removals.
601          * This can only happen when we move towards the beginning of the
602          * buffer, i.e. dst_slot < src_slot.
603          */
604         for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
605                 ret = tree_mod_log_insert_key_locked(fs_info, eb, i + dst_slot,
606                                               MOD_LOG_KEY_REMOVE_WHILE_MOVING);
607                 BUG_ON(ret < 0);
608         }
609
610         ret = tree_mod_alloc(fs_info, flags, &tm);
611         if (ret < 0)
612                 goto out;
613
614         tm->index = eb->start >> PAGE_CACHE_SHIFT;
615         tm->slot = src_slot;
616         tm->move.dst_slot = dst_slot;
617         tm->move.nr_items = nr_items;
618         tm->op = MOD_LOG_MOVE_KEYS;
619
620         ret = __tree_mod_log_insert(fs_info, tm);
621 out:
622         tree_mod_log_write_unlock(fs_info);
623         return ret;
624 }
625
626 static inline void
627 __tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, struct extent_buffer *eb)
628 {
629         int i;
630         u32 nritems;
631         int ret;
632
633         if (btrfs_header_level(eb) == 0)
634                 return;
635
636         nritems = btrfs_header_nritems(eb);
637         for (i = nritems - 1; i >= 0; i--) {
638                 ret = tree_mod_log_insert_key_locked(fs_info, eb, i,
639                                               MOD_LOG_KEY_REMOVE_WHILE_FREEING);
640                 BUG_ON(ret < 0);
641         }
642 }
643
644 static noinline int
645 tree_mod_log_insert_root(struct btrfs_fs_info *fs_info,
646                          struct extent_buffer *old_root,
647                          struct extent_buffer *new_root, gfp_t flags)
648 {
649         struct tree_mod_elem *tm;
650         int ret;
651
652         if (tree_mod_dont_log(fs_info, NULL))
653                 return 0;
654
655         ret = tree_mod_alloc(fs_info, flags, &tm);
656         if (ret < 0)
657                 goto out;
658
659         tm->index = new_root->start >> PAGE_CACHE_SHIFT;
660         tm->old_root.logical = old_root->start;
661         tm->old_root.level = btrfs_header_level(old_root);
662         tm->generation = btrfs_header_generation(old_root);
663         tm->op = MOD_LOG_ROOT_REPLACE;
664
665         ret = __tree_mod_log_insert(fs_info, tm);
666 out:
667         tree_mod_log_write_unlock(fs_info);
668         return ret;
669 }
670
671 static struct tree_mod_elem *
672 __tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
673                       int smallest)
674 {
675         struct rb_root *tm_root;
676         struct rb_node *node;
677         struct tree_mod_elem *cur = NULL;
678         struct tree_mod_elem *found = NULL;
679         u64 index = start >> PAGE_CACHE_SHIFT;
680
681         tree_mod_log_read_lock(fs_info);
682         tm_root = &fs_info->tree_mod_log;
683         node = tm_root->rb_node;
684         while (node) {
685                 cur = container_of(node, struct tree_mod_elem, node);
686                 if (cur->index < index) {
687                         node = node->rb_left;
688                 } else if (cur->index > index) {
689                         node = node->rb_right;
690                 } else if (cur->seq < min_seq) {
691                         node = node->rb_left;
692                 } else if (!smallest) {
693                         /* we want the node with the highest seq */
694                         if (found)
695                                 BUG_ON(found->seq > cur->seq);
696                         found = cur;
697                         node = node->rb_left;
698                 } else if (cur->seq > min_seq) {
699                         /* we want the node with the smallest seq */
700                         if (found)
701                                 BUG_ON(found->seq < cur->seq);
702                         found = cur;
703                         node = node->rb_right;
704                 } else {
705                         found = cur;
706                         break;
707                 }
708         }
709         tree_mod_log_read_unlock(fs_info);
710
711         return found;
712 }
713
714 /*
715  * this returns the element from the log with the smallest time sequence
716  * value that's in the log (the oldest log item). any element with a time
717  * sequence lower than min_seq will be ignored.
718  */
719 static struct tree_mod_elem *
720 tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
721                            u64 min_seq)
722 {
723         return __tree_mod_log_search(fs_info, start, min_seq, 1);
724 }
725
726 /*
727  * this returns the element from the log with the largest time sequence
728  * value that's in the log (the most recent log item). any element with
729  * a time sequence lower than min_seq will be ignored.
730  */
731 static struct tree_mod_elem *
732 tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
733 {
734         return __tree_mod_log_search(fs_info, start, min_seq, 0);
735 }
736
737 static noinline void
738 tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
739                      struct extent_buffer *src, unsigned long dst_offset,
740                      unsigned long src_offset, int nr_items)
741 {
742         int ret;
743         int i;
744
745         if (tree_mod_dont_log(fs_info, NULL))
746                 return;
747
748         if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0) {
749                 tree_mod_log_write_unlock(fs_info);
750                 return;
751         }
752
753         for (i = 0; i < nr_items; i++) {
754                 ret = tree_mod_log_insert_key_locked(fs_info, src,
755                                                      i + src_offset,
756                                                      MOD_LOG_KEY_REMOVE);
757                 BUG_ON(ret < 0);
758                 ret = tree_mod_log_insert_key_locked(fs_info, dst,
759                                                      i + dst_offset,
760                                                      MOD_LOG_KEY_ADD);
761                 BUG_ON(ret < 0);
762         }
763
764         tree_mod_log_write_unlock(fs_info);
765 }
766
767 static inline void
768 tree_mod_log_eb_move(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
769                      int dst_offset, int src_offset, int nr_items)
770 {
771         int ret;
772         ret = tree_mod_log_insert_move(fs_info, dst, dst_offset, src_offset,
773                                        nr_items, GFP_NOFS);
774         BUG_ON(ret < 0);
775 }
776
777 static noinline void
778 tree_mod_log_set_node_key(struct btrfs_fs_info *fs_info,
779                           struct extent_buffer *eb,
780                           struct btrfs_disk_key *disk_key, int slot, int atomic)
781 {
782         int ret;
783
784         ret = tree_mod_log_insert_key_mask(fs_info, eb, slot,
785                                            MOD_LOG_KEY_REPLACE,
786                                            atomic ? GFP_ATOMIC : GFP_NOFS);
787         BUG_ON(ret < 0);
788 }
789
790 static noinline void
791 tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, struct extent_buffer *eb)
792 {
793         if (tree_mod_dont_log(fs_info, eb))
794                 return;
795
796         __tree_mod_log_free_eb(fs_info, eb);
797
798         tree_mod_log_write_unlock(fs_info);
799 }
800
801 static noinline void
802 tree_mod_log_set_root_pointer(struct btrfs_root *root,
803                               struct extent_buffer *new_root_node)
804 {
805         int ret;
806         ret = tree_mod_log_insert_root(root->fs_info, root->node,
807                                        new_root_node, GFP_NOFS);
808         BUG_ON(ret < 0);
809 }
810
811 /*
812  * check if the tree block can be shared by multiple trees
813  */
814 int btrfs_block_can_be_shared(struct btrfs_root *root,
815                               struct extent_buffer *buf)
816 {
817         /*
818          * Tree blocks not in refernece counted trees and tree roots
819          * are never shared. If a block was allocated after the last
820          * snapshot and the block was not allocated by tree relocation,
821          * we know the block is not shared.
822          */
823         if (root->ref_cows &&
824             buf != root->node && buf != root->commit_root &&
825             (btrfs_header_generation(buf) <=
826              btrfs_root_last_snapshot(&root->root_item) ||
827              btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
828                 return 1;
829 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
830         if (root->ref_cows &&
831             btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
832                 return 1;
833 #endif
834         return 0;
835 }
836
837 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
838                                        struct btrfs_root *root,
839                                        struct extent_buffer *buf,
840                                        struct extent_buffer *cow,
841                                        int *last_ref)
842 {
843         u64 refs;
844         u64 owner;
845         u64 flags;
846         u64 new_flags = 0;
847         int ret;
848
849         /*
850          * Backrefs update rules:
851          *
852          * Always use full backrefs for extent pointers in tree block
853          * allocated by tree relocation.
854          *
855          * If a shared tree block is no longer referenced by its owner
856          * tree (btrfs_header_owner(buf) == root->root_key.objectid),
857          * use full backrefs for extent pointers in tree block.
858          *
859          * If a tree block is been relocating
860          * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
861          * use full backrefs for extent pointers in tree block.
862          * The reason for this is some operations (such as drop tree)
863          * are only allowed for blocks use full backrefs.
864          */
865
866         if (btrfs_block_can_be_shared(root, buf)) {
867                 ret = btrfs_lookup_extent_info(trans, root, buf->start,
868                                                buf->len, &refs, &flags);
869                 if (ret)
870                         return ret;
871                 if (refs == 0) {
872                         ret = -EROFS;
873                         btrfs_std_error(root->fs_info, ret);
874                         return ret;
875                 }
876         } else {
877                 refs = 1;
878                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
879                     btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
880                         flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
881                 else
882                         flags = 0;
883         }
884
885         owner = btrfs_header_owner(buf);
886         BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
887                !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
888
889         if (refs > 1) {
890                 if ((owner == root->root_key.objectid ||
891                      root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
892                     !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
893                         ret = btrfs_inc_ref(trans, root, buf, 1, 1);
894                         BUG_ON(ret); /* -ENOMEM */
895
896                         if (root->root_key.objectid ==
897                             BTRFS_TREE_RELOC_OBJECTID) {
898                                 ret = btrfs_dec_ref(trans, root, buf, 0, 1);
899                                 BUG_ON(ret); /* -ENOMEM */
900                                 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
901                                 BUG_ON(ret); /* -ENOMEM */
902                         }
903                         new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
904                 } else {
905
906                         if (root->root_key.objectid ==
907                             BTRFS_TREE_RELOC_OBJECTID)
908                                 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
909                         else
910                                 ret = btrfs_inc_ref(trans, root, cow, 0, 1);
911                         BUG_ON(ret); /* -ENOMEM */
912                 }
913                 if (new_flags != 0) {
914                         ret = btrfs_set_disk_extent_flags(trans, root,
915                                                           buf->start,
916                                                           buf->len,
917                                                           new_flags, 0);
918                         if (ret)
919                                 return ret;
920                 }
921         } else {
922                 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
923                         if (root->root_key.objectid ==
924                             BTRFS_TREE_RELOC_OBJECTID)
925                                 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
926                         else
927                                 ret = btrfs_inc_ref(trans, root, cow, 0, 1);
928                         BUG_ON(ret); /* -ENOMEM */
929                         ret = btrfs_dec_ref(trans, root, buf, 1, 1);
930                         BUG_ON(ret); /* -ENOMEM */
931                 }
932                 tree_mod_log_free_eb(root->fs_info, buf);
933                 clean_tree_block(trans, root, buf);
934                 *last_ref = 1;
935         }
936         return 0;
937 }
938
939 /*
940  * does the dirty work in cow of a single block.  The parent block (if
941  * supplied) is updated to point to the new cow copy.  The new buffer is marked
942  * dirty and returned locked.  If you modify the block it needs to be marked
943  * dirty again.
944  *
945  * search_start -- an allocation hint for the new block
946  *
947  * empty_size -- a hint that you plan on doing more cow.  This is the size in
948  * bytes the allocator should try to find free next to the block it returns.
949  * This is just a hint and may be ignored by the allocator.
950  */
951 static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
952                              struct btrfs_root *root,
953                              struct extent_buffer *buf,
954                              struct extent_buffer *parent, int parent_slot,
955                              struct extent_buffer **cow_ret,
956                              u64 search_start, u64 empty_size)
957 {
958         struct btrfs_disk_key disk_key;
959         struct extent_buffer *cow;
960         int level, ret;
961         int last_ref = 0;
962         int unlock_orig = 0;
963         u64 parent_start;
964
965         if (*cow_ret == buf)
966                 unlock_orig = 1;
967
968         btrfs_assert_tree_locked(buf);
969
970         WARN_ON(root->ref_cows && trans->transid !=
971                 root->fs_info->running_transaction->transid);
972         WARN_ON(root->ref_cows && trans->transid != root->last_trans);
973
974         level = btrfs_header_level(buf);
975
976         if (level == 0)
977                 btrfs_item_key(buf, &disk_key, 0);
978         else
979                 btrfs_node_key(buf, &disk_key, 0);
980
981         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
982                 if (parent)
983                         parent_start = parent->start;
984                 else
985                         parent_start = 0;
986         } else
987                 parent_start = 0;
988
989         cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start,
990                                      root->root_key.objectid, &disk_key,
991                                      level, search_start, empty_size);
992         if (IS_ERR(cow))
993                 return PTR_ERR(cow);
994
995         /* cow is set to blocking by btrfs_init_new_buffer */
996
997         copy_extent_buffer(cow, buf, 0, 0, cow->len);
998         btrfs_set_header_bytenr(cow, cow->start);
999         btrfs_set_header_generation(cow, trans->transid);
1000         btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
1001         btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
1002                                      BTRFS_HEADER_FLAG_RELOC);
1003         if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1004                 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
1005         else
1006                 btrfs_set_header_owner(cow, root->root_key.objectid);
1007
1008         write_extent_buffer(cow, root->fs_info->fsid,
1009                             (unsigned long)btrfs_header_fsid(cow),
1010                             BTRFS_FSID_SIZE);
1011
1012         ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
1013         if (ret) {
1014                 btrfs_abort_transaction(trans, root, ret);
1015                 return ret;
1016         }
1017
1018         if (root->ref_cows)
1019                 btrfs_reloc_cow_block(trans, root, buf, cow);
1020
1021         if (buf == root->node) {
1022                 WARN_ON(parent && parent != buf);
1023                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1024                     btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1025                         parent_start = buf->start;
1026                 else
1027                         parent_start = 0;
1028
1029                 extent_buffer_get(cow);
1030                 tree_mod_log_set_root_pointer(root, cow);
1031                 rcu_assign_pointer(root->node, cow);
1032
1033                 btrfs_free_tree_block(trans, root, buf, parent_start,
1034                                       last_ref);
1035                 free_extent_buffer(buf);
1036                 add_root_to_dirty_list(root);
1037         } else {
1038                 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1039                         parent_start = parent->start;
1040                 else
1041                         parent_start = 0;
1042
1043                 WARN_ON(trans->transid != btrfs_header_generation(parent));
1044                 tree_mod_log_insert_key(root->fs_info, parent, parent_slot,
1045                                         MOD_LOG_KEY_REPLACE);
1046                 btrfs_set_node_blockptr(parent, parent_slot,
1047                                         cow->start);
1048                 btrfs_set_node_ptr_generation(parent, parent_slot,
1049                                               trans->transid);
1050                 btrfs_mark_buffer_dirty(parent);
1051                 btrfs_free_tree_block(trans, root, buf, parent_start,
1052                                       last_ref);
1053         }
1054         if (unlock_orig)
1055                 btrfs_tree_unlock(buf);
1056         free_extent_buffer_stale(buf);
1057         btrfs_mark_buffer_dirty(cow);
1058         *cow_ret = cow;
1059         return 0;
1060 }
1061
1062 /*
1063  * returns the logical address of the oldest predecessor of the given root.
1064  * entries older than time_seq are ignored.
1065  */
1066 static struct tree_mod_elem *
1067 __tree_mod_log_oldest_root(struct btrfs_fs_info *fs_info,
1068                            struct btrfs_root *root, u64 time_seq)
1069 {
1070         struct tree_mod_elem *tm;
1071         struct tree_mod_elem *found = NULL;
1072         u64 root_logical = root->node->start;
1073         int looped = 0;
1074
1075         if (!time_seq)
1076                 return 0;
1077
1078         /*
1079          * the very last operation that's logged for a root is the replacement
1080          * operation (if it is replaced at all). this has the index of the *new*
1081          * root, making it the very first operation that's logged for this root.
1082          */
1083         while (1) {
1084                 tm = tree_mod_log_search_oldest(fs_info, root_logical,
1085                                                 time_seq);
1086                 if (!looped && !tm)
1087                         return 0;
1088                 /*
1089                  * if there are no tree operation for the oldest root, we simply
1090                  * return it. this should only happen if that (old) root is at
1091                  * level 0.
1092                  */
1093                 if (!tm)
1094                         break;
1095
1096                 /*
1097                  * if there's an operation that's not a root replacement, we
1098                  * found the oldest version of our root. normally, we'll find a
1099                  * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1100                  */
1101                 if (tm->op != MOD_LOG_ROOT_REPLACE)
1102                         break;
1103
1104                 found = tm;
1105                 root_logical = tm->old_root.logical;
1106                 BUG_ON(root_logical == root->node->start);
1107                 looped = 1;
1108         }
1109
1110         /* if there's no old root to return, return what we found instead */
1111         if (!found)
1112                 found = tm;
1113
1114         return found;
1115 }
1116
1117 /*
1118  * tm is a pointer to the first operation to rewind within eb. then, all
1119  * previous operations will be rewinded (until we reach something older than
1120  * time_seq).
1121  */
1122 static void
1123 __tree_mod_log_rewind(struct extent_buffer *eb, u64 time_seq,
1124                       struct tree_mod_elem *first_tm)
1125 {
1126         u32 n;
1127         struct rb_node *next;
1128         struct tree_mod_elem *tm = first_tm;
1129         unsigned long o_dst;
1130         unsigned long o_src;
1131         unsigned long p_size = sizeof(struct btrfs_key_ptr);
1132
1133         n = btrfs_header_nritems(eb);
1134         while (tm && tm->seq >= time_seq) {
1135                 /*
1136                  * all the operations are recorded with the operator used for
1137                  * the modification. as we're going backwards, we do the
1138                  * opposite of each operation here.
1139                  */
1140                 switch (tm->op) {
1141                 case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1142                         BUG_ON(tm->slot < n);
1143                 case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1144                 case MOD_LOG_KEY_REMOVE:
1145                         btrfs_set_node_key(eb, &tm->key, tm->slot);
1146                         btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1147                         btrfs_set_node_ptr_generation(eb, tm->slot,
1148                                                       tm->generation);
1149                         n++;
1150                         break;
1151                 case MOD_LOG_KEY_REPLACE:
1152                         BUG_ON(tm->slot >= n);
1153                         btrfs_set_node_key(eb, &tm->key, tm->slot);
1154                         btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1155                         btrfs_set_node_ptr_generation(eb, tm->slot,
1156                                                       tm->generation);
1157                         break;
1158                 case MOD_LOG_KEY_ADD:
1159                         /* if a move operation is needed it's in the log */
1160                         n--;
1161                         break;
1162                 case MOD_LOG_MOVE_KEYS:
1163                         o_dst = btrfs_node_key_ptr_offset(tm->slot);
1164                         o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1165                         memmove_extent_buffer(eb, o_dst, o_src,
1166                                               tm->move.nr_items * p_size);
1167                         break;
1168                 case MOD_LOG_ROOT_REPLACE:
1169                         /*
1170                          * this operation is special. for roots, this must be
1171                          * handled explicitly before rewinding.
1172                          * for non-roots, this operation may exist if the node
1173                          * was a root: root A -> child B; then A gets empty and
1174                          * B is promoted to the new root. in the mod log, we'll
1175                          * have a root-replace operation for B, a tree block
1176                          * that is no root. we simply ignore that operation.
1177                          */
1178                         break;
1179                 }
1180                 next = rb_next(&tm->node);
1181                 if (!next)
1182                         break;
1183                 tm = container_of(next, struct tree_mod_elem, node);
1184                 if (tm->index != first_tm->index)
1185                         break;
1186         }
1187         btrfs_set_header_nritems(eb, n);
1188 }
1189
1190 static struct extent_buffer *
1191 tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1192                     u64 time_seq)
1193 {
1194         struct extent_buffer *eb_rewin;
1195         struct tree_mod_elem *tm;
1196
1197         if (!time_seq)
1198                 return eb;
1199
1200         if (btrfs_header_level(eb) == 0)
1201                 return eb;
1202
1203         tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1204         if (!tm)
1205                 return eb;
1206
1207         if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1208                 BUG_ON(tm->slot != 0);
1209                 eb_rewin = alloc_dummy_extent_buffer(eb->start,
1210                                                 fs_info->tree_root->nodesize);
1211                 BUG_ON(!eb_rewin);
1212                 btrfs_set_header_bytenr(eb_rewin, eb->start);
1213                 btrfs_set_header_backref_rev(eb_rewin,
1214                                              btrfs_header_backref_rev(eb));
1215                 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1216                 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1217         } else {
1218                 eb_rewin = btrfs_clone_extent_buffer(eb);
1219                 BUG_ON(!eb_rewin);
1220         }
1221
1222         extent_buffer_get(eb_rewin);
1223         free_extent_buffer(eb);
1224
1225         __tree_mod_log_rewind(eb_rewin, time_seq, tm);
1226         WARN_ON(btrfs_header_nritems(eb_rewin) >
1227                 BTRFS_NODEPTRS_PER_BLOCK(fs_info->fs_root));
1228
1229         return eb_rewin;
1230 }
1231
1232 /*
1233  * get_old_root() rewinds the state of @root's root node to the given @time_seq
1234  * value. If there are no changes, the current root->root_node is returned. If
1235  * anything changed in between, there's a fresh buffer allocated on which the
1236  * rewind operations are done. In any case, the returned buffer is read locked.
1237  * Returns NULL on error (with no locks held).
1238  */
1239 static inline struct extent_buffer *
1240 get_old_root(struct btrfs_root *root, u64 time_seq)
1241 {
1242         struct tree_mod_elem *tm;
1243         struct extent_buffer *eb;
1244         struct tree_mod_root *old_root = NULL;
1245         u64 old_generation = 0;
1246         u64 logical;
1247         u32 blocksize;
1248
1249         eb = btrfs_read_lock_root_node(root);
1250         tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
1251         if (!tm)
1252                 return root->node;
1253
1254         if (tm->op == MOD_LOG_ROOT_REPLACE) {
1255                 old_root = &tm->old_root;
1256                 old_generation = tm->generation;
1257                 logical = old_root->logical;
1258         } else {
1259                 logical = root->node->start;
1260         }
1261
1262         tm = tree_mod_log_search(root->fs_info, logical, time_seq);
1263         if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1264                 btrfs_tree_read_unlock(root->node);
1265                 free_extent_buffer(root->node);
1266                 blocksize = btrfs_level_size(root, old_root->level);
1267                 eb = read_tree_block(root, logical, blocksize, 0);
1268                 if (!eb) {
1269                         pr_warn("btrfs: failed to read tree block %llu from get_old_root\n",
1270                                 logical);
1271                         WARN_ON(1);
1272                 } else {
1273                         eb = btrfs_clone_extent_buffer(eb);
1274                 }
1275         } else if (old_root) {
1276                 btrfs_tree_read_unlock(root->node);
1277                 free_extent_buffer(root->node);
1278                 eb = alloc_dummy_extent_buffer(logical, root->nodesize);
1279         } else {
1280                 eb = btrfs_clone_extent_buffer(root->node);
1281                 btrfs_tree_read_unlock(root->node);
1282                 free_extent_buffer(root->node);
1283         }
1284
1285         if (!eb)
1286                 return NULL;
1287         extent_buffer_get(eb);
1288         btrfs_tree_read_lock(eb);
1289         if (old_root) {
1290                 btrfs_set_header_bytenr(eb, eb->start);
1291                 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1292                 btrfs_set_header_owner(eb, root->root_key.objectid);
1293                 btrfs_set_header_level(eb, old_root->level);
1294                 btrfs_set_header_generation(eb, old_generation);
1295         }
1296         if (tm)
1297                 __tree_mod_log_rewind(eb, time_seq, tm);
1298         else
1299                 WARN_ON(btrfs_header_level(eb) != 0);
1300         WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(root));
1301
1302         return eb;
1303 }
1304
1305 int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
1306 {
1307         struct tree_mod_elem *tm;
1308         int level;
1309
1310         tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
1311         if (tm && tm->op == MOD_LOG_ROOT_REPLACE) {
1312                 level = tm->old_root.level;
1313         } else {
1314                 rcu_read_lock();
1315                 level = btrfs_header_level(root->node);
1316                 rcu_read_unlock();
1317         }
1318
1319         return level;
1320 }
1321
1322 static inline int should_cow_block(struct btrfs_trans_handle *trans,
1323                                    struct btrfs_root *root,
1324                                    struct extent_buffer *buf)
1325 {
1326         /* ensure we can see the force_cow */
1327         smp_rmb();
1328
1329         /*
1330          * We do not need to cow a block if
1331          * 1) this block is not created or changed in this transaction;
1332          * 2) this block does not belong to TREE_RELOC tree;
1333          * 3) the root is not forced COW.
1334          *
1335          * What is forced COW:
1336          *    when we create snapshot during commiting the transaction,
1337          *    after we've finished coping src root, we must COW the shared
1338          *    block to ensure the metadata consistency.
1339          */
1340         if (btrfs_header_generation(buf) == trans->transid &&
1341             !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1342             !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1343               btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1344             !root->force_cow)
1345                 return 0;
1346         return 1;
1347 }
1348
1349 /*
1350  * cows a single block, see __btrfs_cow_block for the real work.
1351  * This version of it has extra checks so that a block isn't cow'd more than
1352  * once per transaction, as long as it hasn't been written yet
1353  */
1354 noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1355                     struct btrfs_root *root, struct extent_buffer *buf,
1356                     struct extent_buffer *parent, int parent_slot,
1357                     struct extent_buffer **cow_ret)
1358 {
1359         u64 search_start;
1360         int ret;
1361
1362         if (trans->transaction != root->fs_info->running_transaction) {
1363                 printk(KERN_CRIT "trans %llu running %llu\n",
1364                        (unsigned long long)trans->transid,
1365                        (unsigned long long)
1366                        root->fs_info->running_transaction->transid);
1367                 WARN_ON(1);
1368         }
1369         if (trans->transid != root->fs_info->generation) {
1370                 printk(KERN_CRIT "trans %llu running %llu\n",
1371                        (unsigned long long)trans->transid,
1372                        (unsigned long long)root->fs_info->generation);
1373                 WARN_ON(1);
1374         }
1375
1376         if (!should_cow_block(trans, root, buf)) {
1377                 *cow_ret = buf;
1378                 return 0;
1379         }
1380
1381         search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
1382
1383         if (parent)
1384                 btrfs_set_lock_blocking(parent);
1385         btrfs_set_lock_blocking(buf);
1386
1387         ret = __btrfs_cow_block(trans, root, buf, parent,
1388                                  parent_slot, cow_ret, search_start, 0);
1389
1390         trace_btrfs_cow_block(root, buf, *cow_ret);
1391
1392         return ret;
1393 }
1394
1395 /*
1396  * helper function for defrag to decide if two blocks pointed to by a
1397  * node are actually close by
1398  */
1399 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1400 {
1401         if (blocknr < other && other - (blocknr + blocksize) < 32768)
1402                 return 1;
1403         if (blocknr > other && blocknr - (other + blocksize) < 32768)
1404                 return 1;
1405         return 0;
1406 }
1407
1408 /*
1409  * compare two keys in a memcmp fashion
1410  */
1411 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
1412 {
1413         struct btrfs_key k1;
1414
1415         btrfs_disk_key_to_cpu(&k1, disk);
1416
1417         return btrfs_comp_cpu_keys(&k1, k2);
1418 }
1419
1420 /*
1421  * same as comp_keys only with two btrfs_key's
1422  */
1423 int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2)
1424 {
1425         if (k1->objectid > k2->objectid)
1426                 return 1;
1427         if (k1->objectid < k2->objectid)
1428                 return -1;
1429         if (k1->type > k2->type)
1430                 return 1;
1431         if (k1->type < k2->type)
1432                 return -1;
1433         if (k1->offset > k2->offset)
1434                 return 1;
1435         if (k1->offset < k2->offset)
1436                 return -1;
1437         return 0;
1438 }
1439
1440 /*
1441  * this is used by the defrag code to go through all the
1442  * leaves pointed to by a node and reallocate them so that
1443  * disk order is close to key order
1444  */
1445 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1446                        struct btrfs_root *root, struct extent_buffer *parent,
1447                        int start_slot, int cache_only, u64 *last_ret,
1448                        struct btrfs_key *progress)
1449 {
1450         struct extent_buffer *cur;
1451         u64 blocknr;
1452         u64 gen;
1453         u64 search_start = *last_ret;
1454         u64 last_block = 0;
1455         u64 other;
1456         u32 parent_nritems;
1457         int end_slot;
1458         int i;
1459         int err = 0;
1460         int parent_level;
1461         int uptodate;
1462         u32 blocksize;
1463         int progress_passed = 0;
1464         struct btrfs_disk_key disk_key;
1465
1466         parent_level = btrfs_header_level(parent);
1467         if (cache_only && parent_level != 1)
1468                 return 0;
1469
1470         if (trans->transaction != root->fs_info->running_transaction)
1471                 WARN_ON(1);
1472         if (trans->transid != root->fs_info->generation)
1473                 WARN_ON(1);
1474
1475         parent_nritems = btrfs_header_nritems(parent);
1476         blocksize = btrfs_level_size(root, parent_level - 1);
1477         end_slot = parent_nritems;
1478
1479         if (parent_nritems == 1)
1480                 return 0;
1481
1482         btrfs_set_lock_blocking(parent);
1483
1484         for (i = start_slot; i < end_slot; i++) {
1485                 int close = 1;
1486
1487                 btrfs_node_key(parent, &disk_key, i);
1488                 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1489                         continue;
1490
1491                 progress_passed = 1;
1492                 blocknr = btrfs_node_blockptr(parent, i);
1493                 gen = btrfs_node_ptr_generation(parent, i);
1494                 if (last_block == 0)
1495                         last_block = blocknr;
1496
1497                 if (i > 0) {
1498                         other = btrfs_node_blockptr(parent, i - 1);
1499                         close = close_blocks(blocknr, other, blocksize);
1500                 }
1501                 if (!close && i < end_slot - 2) {
1502                         other = btrfs_node_blockptr(parent, i + 1);
1503                         close = close_blocks(blocknr, other, blocksize);
1504                 }
1505                 if (close) {
1506                         last_block = blocknr;
1507                         continue;
1508                 }
1509
1510                 cur = btrfs_find_tree_block(root, blocknr, blocksize);
1511                 if (cur)
1512                         uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1513                 else
1514                         uptodate = 0;
1515                 if (!cur || !uptodate) {
1516                         if (cache_only) {
1517                                 free_extent_buffer(cur);
1518                                 continue;
1519                         }
1520                         if (!cur) {
1521                                 cur = read_tree_block(root, blocknr,
1522                                                          blocksize, gen);
1523                                 if (!cur)
1524                                         return -EIO;
1525                         } else if (!uptodate) {
1526                                 err = btrfs_read_buffer(cur, gen);
1527                                 if (err) {
1528                                         free_extent_buffer(cur);
1529                                         return err;
1530                                 }
1531                         }
1532                 }
1533                 if (search_start == 0)
1534                         search_start = last_block;
1535
1536                 btrfs_tree_lock(cur);
1537                 btrfs_set_lock_blocking(cur);
1538                 err = __btrfs_cow_block(trans, root, cur, parent, i,
1539                                         &cur, search_start,
1540                                         min(16 * blocksize,
1541                                             (end_slot - i) * blocksize));
1542                 if (err) {
1543                         btrfs_tree_unlock(cur);
1544                         free_extent_buffer(cur);
1545                         break;
1546                 }
1547                 search_start = cur->start;
1548                 last_block = cur->start;
1549                 *last_ret = search_start;
1550                 btrfs_tree_unlock(cur);
1551                 free_extent_buffer(cur);
1552         }
1553         return err;
1554 }
1555
1556 /*
1557  * The leaf data grows from end-to-front in the node.
1558  * this returns the address of the start of the last item,
1559  * which is the stop of the leaf data stack
1560  */
1561 static inline unsigned int leaf_data_end(struct btrfs_root *root,
1562                                          struct extent_buffer *leaf)
1563 {
1564         u32 nr = btrfs_header_nritems(leaf);
1565         if (nr == 0)
1566                 return BTRFS_LEAF_DATA_SIZE(root);
1567         return btrfs_item_offset_nr(leaf, nr - 1);
1568 }
1569
1570
1571 /*
1572  * search for key in the extent_buffer.  The items start at offset p,
1573  * and they are item_size apart.  There are 'max' items in p.
1574  *
1575  * the slot in the array is returned via slot, and it points to
1576  * the place where you would insert key if it is not found in
1577  * the array.
1578  *
1579  * slot may point to max if the key is bigger than all of the keys
1580  */
1581 static noinline int generic_bin_search(struct extent_buffer *eb,
1582                                        unsigned long p,
1583                                        int item_size, struct btrfs_key *key,
1584                                        int max, int *slot)
1585 {
1586         int low = 0;
1587         int high = max;
1588         int mid;
1589         int ret;
1590         struct btrfs_disk_key *tmp = NULL;
1591         struct btrfs_disk_key unaligned;
1592         unsigned long offset;
1593         char *kaddr = NULL;
1594         unsigned long map_start = 0;
1595         unsigned long map_len = 0;
1596         int err;
1597
1598         while (low < high) {
1599                 mid = (low + high) / 2;
1600                 offset = p + mid * item_size;
1601
1602                 if (!kaddr || offset < map_start ||
1603                     (offset + sizeof(struct btrfs_disk_key)) >
1604                     map_start + map_len) {
1605
1606                         err = map_private_extent_buffer(eb, offset,
1607                                                 sizeof(struct btrfs_disk_key),
1608                                                 &kaddr, &map_start, &map_len);
1609
1610                         if (!err) {
1611                                 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1612                                                         map_start);
1613                         } else {
1614                                 read_extent_buffer(eb, &unaligned,
1615                                                    offset, sizeof(unaligned));
1616                                 tmp = &unaligned;
1617                         }
1618
1619                 } else {
1620                         tmp = (struct btrfs_disk_key *)(kaddr + offset -
1621                                                         map_start);
1622                 }
1623                 ret = comp_keys(tmp, key);
1624
1625                 if (ret < 0)
1626                         low = mid + 1;
1627                 else if (ret > 0)
1628                         high = mid;
1629                 else {
1630                         *slot = mid;
1631                         return 0;
1632                 }
1633         }
1634         *slot = low;
1635         return 1;
1636 }
1637
1638 /*
1639  * simple bin_search frontend that does the right thing for
1640  * leaves vs nodes
1641  */
1642 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
1643                       int level, int *slot)
1644 {
1645         if (level == 0)
1646                 return generic_bin_search(eb,
1647                                           offsetof(struct btrfs_leaf, items),
1648                                           sizeof(struct btrfs_item),
1649                                           key, btrfs_header_nritems(eb),
1650                                           slot);
1651         else
1652                 return generic_bin_search(eb,
1653                                           offsetof(struct btrfs_node, ptrs),
1654                                           sizeof(struct btrfs_key_ptr),
1655                                           key, btrfs_header_nritems(eb),
1656                                           slot);
1657 }
1658
1659 int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
1660                      int level, int *slot)
1661 {
1662         return bin_search(eb, key, level, slot);
1663 }
1664
1665 static void root_add_used(struct btrfs_root *root, u32 size)
1666 {
1667         spin_lock(&root->accounting_lock);
1668         btrfs_set_root_used(&root->root_item,
1669                             btrfs_root_used(&root->root_item) + size);
1670         spin_unlock(&root->accounting_lock);
1671 }
1672
1673 static void root_sub_used(struct btrfs_root *root, u32 size)
1674 {
1675         spin_lock(&root->accounting_lock);
1676         btrfs_set_root_used(&root->root_item,
1677                             btrfs_root_used(&root->root_item) - size);
1678         spin_unlock(&root->accounting_lock);
1679 }
1680
1681 /* given a node and slot number, this reads the blocks it points to.  The
1682  * extent buffer is returned with a reference taken (but unlocked).
1683  * NULL is returned on error.
1684  */
1685 static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root,
1686                                    struct extent_buffer *parent, int slot)
1687 {
1688         int level = btrfs_header_level(parent);
1689         if (slot < 0)
1690                 return NULL;
1691         if (slot >= btrfs_header_nritems(parent))
1692                 return NULL;
1693
1694         BUG_ON(level == 0);
1695
1696         return read_tree_block(root, btrfs_node_blockptr(parent, slot),
1697                        btrfs_level_size(root, level - 1),
1698                        btrfs_node_ptr_generation(parent, slot));
1699 }
1700
1701 /*
1702  * node level balancing, used to make sure nodes are in proper order for
1703  * item deletion.  We balance from the top down, so we have to make sure
1704  * that a deletion won't leave an node completely empty later on.
1705  */
1706 static noinline int balance_level(struct btrfs_trans_handle *trans,
1707                          struct btrfs_root *root,
1708                          struct btrfs_path *path, int level)
1709 {
1710         struct extent_buffer *right = NULL;
1711         struct extent_buffer *mid;
1712         struct extent_buffer *left = NULL;
1713         struct extent_buffer *parent = NULL;
1714         int ret = 0;
1715         int wret;
1716         int pslot;
1717         int orig_slot = path->slots[level];
1718         u64 orig_ptr;
1719
1720         if (level == 0)
1721                 return 0;
1722
1723         mid = path->nodes[level];
1724
1725         WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1726                 path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1727         WARN_ON(btrfs_header_generation(mid) != trans->transid);
1728
1729         orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1730
1731         if (level < BTRFS_MAX_LEVEL - 1) {
1732                 parent = path->nodes[level + 1];
1733                 pslot = path->slots[level + 1];
1734         }
1735
1736         /*
1737          * deal with the case where there is only one pointer in the root
1738          * by promoting the node below to a root
1739          */
1740         if (!parent) {
1741                 struct extent_buffer *child;
1742
1743                 if (btrfs_header_nritems(mid) != 1)
1744                         return 0;
1745
1746                 /* promote the child to a root */
1747                 child = read_node_slot(root, mid, 0);
1748                 if (!child) {
1749                         ret = -EROFS;
1750                         btrfs_std_error(root->fs_info, ret);
1751                         goto enospc;
1752                 }
1753
1754                 btrfs_tree_lock(child);
1755                 btrfs_set_lock_blocking(child);
1756                 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1757                 if (ret) {
1758                         btrfs_tree_unlock(child);
1759                         free_extent_buffer(child);
1760                         goto enospc;
1761                 }
1762
1763                 tree_mod_log_free_eb(root->fs_info, root->node);
1764                 tree_mod_log_set_root_pointer(root, child);
1765                 rcu_assign_pointer(root->node, child);
1766
1767                 add_root_to_dirty_list(root);
1768                 btrfs_tree_unlock(child);
1769
1770                 path->locks[level] = 0;
1771                 path->nodes[level] = NULL;
1772                 clean_tree_block(trans, root, mid);
1773                 btrfs_tree_unlock(mid);
1774                 /* once for the path */
1775                 free_extent_buffer(mid);
1776
1777                 root_sub_used(root, mid->len);
1778                 btrfs_free_tree_block(trans, root, mid, 0, 1);
1779                 /* once for the root ptr */
1780                 free_extent_buffer_stale(mid);
1781                 return 0;
1782         }
1783         if (btrfs_header_nritems(mid) >
1784             BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
1785                 return 0;
1786
1787         left = read_node_slot(root, parent, pslot - 1);
1788         if (left) {
1789                 btrfs_tree_lock(left);
1790                 btrfs_set_lock_blocking(left);
1791                 wret = btrfs_cow_block(trans, root, left,
1792                                        parent, pslot - 1, &left);
1793                 if (wret) {
1794                         ret = wret;
1795                         goto enospc;
1796                 }
1797         }
1798         right = read_node_slot(root, parent, pslot + 1);
1799         if (right) {
1800                 btrfs_tree_lock(right);
1801                 btrfs_set_lock_blocking(right);
1802                 wret = btrfs_cow_block(trans, root, right,
1803                                        parent, pslot + 1, &right);
1804                 if (wret) {
1805                         ret = wret;
1806                         goto enospc;
1807                 }
1808         }
1809
1810         /* first, try to make some room in the middle buffer */
1811         if (left) {
1812                 orig_slot += btrfs_header_nritems(left);
1813                 wret = push_node_left(trans, root, left, mid, 1);
1814                 if (wret < 0)
1815                         ret = wret;
1816         }
1817
1818         /*
1819          * then try to empty the right most buffer into the middle
1820          */
1821         if (right) {
1822                 wret = push_node_left(trans, root, mid, right, 1);
1823                 if (wret < 0 && wret != -ENOSPC)
1824                         ret = wret;
1825                 if (btrfs_header_nritems(right) == 0) {
1826                         clean_tree_block(trans, root, right);
1827                         btrfs_tree_unlock(right);
1828                         del_ptr(trans, root, path, level + 1, pslot + 1, 1);
1829                         root_sub_used(root, right->len);
1830                         btrfs_free_tree_block(trans, root, right, 0, 1);
1831                         free_extent_buffer_stale(right);
1832                         right = NULL;
1833                 } else {
1834                         struct btrfs_disk_key right_key;
1835                         btrfs_node_key(right, &right_key, 0);
1836                         tree_mod_log_set_node_key(root->fs_info, parent,
1837                                                   &right_key, pslot + 1, 0);
1838                         btrfs_set_node_key(parent, &right_key, pslot + 1);
1839                         btrfs_mark_buffer_dirty(parent);
1840                 }
1841         }
1842         if (btrfs_header_nritems(mid) == 1) {
1843                 /*
1844                  * we're not allowed to leave a node with one item in the
1845                  * tree during a delete.  A deletion from lower in the tree
1846                  * could try to delete the only pointer in this node.
1847                  * So, pull some keys from the left.
1848                  * There has to be a left pointer at this point because
1849                  * otherwise we would have pulled some pointers from the
1850                  * right
1851                  */
1852                 if (!left) {
1853                         ret = -EROFS;
1854                         btrfs_std_error(root->fs_info, ret);
1855                         goto enospc;
1856                 }
1857                 wret = balance_node_right(trans, root, mid, left);
1858                 if (wret < 0) {
1859                         ret = wret;
1860                         goto enospc;
1861                 }
1862                 if (wret == 1) {
1863                         wret = push_node_left(trans, root, left, mid, 1);
1864                         if (wret < 0)
1865                                 ret = wret;
1866                 }
1867                 BUG_ON(wret == 1);
1868         }
1869         if (btrfs_header_nritems(mid) == 0) {
1870                 clean_tree_block(trans, root, mid);
1871                 btrfs_tree_unlock(mid);
1872                 del_ptr(trans, root, path, level + 1, pslot, 1);
1873                 root_sub_used(root, mid->len);
1874                 btrfs_free_tree_block(trans, root, mid, 0, 1);
1875                 free_extent_buffer_stale(mid);
1876                 mid = NULL;
1877         } else {
1878                 /* update the parent key to reflect our changes */
1879                 struct btrfs_disk_key mid_key;
1880                 btrfs_node_key(mid, &mid_key, 0);
1881                 tree_mod_log_set_node_key(root->fs_info, parent, &mid_key,
1882                                           pslot, 0);
1883                 btrfs_set_node_key(parent, &mid_key, pslot);
1884                 btrfs_mark_buffer_dirty(parent);
1885         }
1886
1887         /* update the path */
1888         if (left) {
1889                 if (btrfs_header_nritems(left) > orig_slot) {
1890                         extent_buffer_get(left);
1891                         /* left was locked after cow */
1892                         path->nodes[level] = left;
1893                         path->slots[level + 1] -= 1;
1894                         path->slots[level] = orig_slot;
1895                         if (mid) {
1896                                 btrfs_tree_unlock(mid);
1897                                 free_extent_buffer(mid);
1898                         }
1899                 } else {
1900                         orig_slot -= btrfs_header_nritems(left);
1901                         path->slots[level] = orig_slot;
1902                 }
1903         }
1904         /* double check we haven't messed things up */
1905         if (orig_ptr !=
1906             btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1907                 BUG();
1908 enospc:
1909         if (right) {
1910                 btrfs_tree_unlock(right);
1911                 free_extent_buffer(right);
1912         }
1913         if (left) {
1914                 if (path->nodes[level] != left)
1915                         btrfs_tree_unlock(left);
1916                 free_extent_buffer(left);
1917         }
1918         return ret;
1919 }
1920
1921 /* Node balancing for insertion.  Here we only split or push nodes around
1922  * when they are completely full.  This is also done top down, so we
1923  * have to be pessimistic.
1924  */
1925 static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1926                                           struct btrfs_root *root,
1927                                           struct btrfs_path *path, int level)
1928 {
1929         struct extent_buffer *right = NULL;
1930         struct extent_buffer *mid;
1931         struct extent_buffer *left = NULL;
1932         struct extent_buffer *parent = NULL;
1933         int ret = 0;
1934         int wret;
1935         int pslot;
1936         int orig_slot = path->slots[level];
1937
1938         if (level == 0)
1939                 return 1;
1940
1941         mid = path->nodes[level];
1942         WARN_ON(btrfs_header_generation(mid) != trans->transid);
1943
1944         if (level < BTRFS_MAX_LEVEL - 1) {
1945                 parent = path->nodes[level + 1];
1946                 pslot = path->slots[level + 1];
1947         }
1948
1949         if (!parent)
1950                 return 1;
1951
1952         left = read_node_slot(root, parent, pslot - 1);
1953
1954         /* first, try to make some room in the middle buffer */
1955         if (left) {
1956                 u32 left_nr;
1957
1958                 btrfs_tree_lock(left);
1959                 btrfs_set_lock_blocking(left);
1960
1961                 left_nr = btrfs_header_nritems(left);
1962                 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1963                         wret = 1;
1964                 } else {
1965                         ret = btrfs_cow_block(trans, root, left, parent,
1966                                               pslot - 1, &left);
1967                         if (ret)
1968                                 wret = 1;
1969                         else {
1970                                 wret = push_node_left(trans, root,
1971                                                       left, mid, 0);
1972                         }
1973                 }
1974                 if (wret < 0)
1975                         ret = wret;
1976                 if (wret == 0) {
1977                         struct btrfs_disk_key disk_key;
1978                         orig_slot += left_nr;
1979                         btrfs_node_key(mid, &disk_key, 0);
1980                         tree_mod_log_set_node_key(root->fs_info, parent,
1981                                                   &disk_key, pslot, 0);
1982                         btrfs_set_node_key(parent, &disk_key, pslot);
1983                         btrfs_mark_buffer_dirty(parent);
1984                         if (btrfs_header_nritems(left) > orig_slot) {
1985                                 path->nodes[level] = left;
1986                                 path->slots[level + 1] -= 1;
1987                                 path->slots[level] = orig_slot;
1988                                 btrfs_tree_unlock(mid);
1989                                 free_extent_buffer(mid);
1990                         } else {
1991                                 orig_slot -=
1992                                         btrfs_header_nritems(left);
1993                                 path->slots[level] = orig_slot;
1994                                 btrfs_tree_unlock(left);
1995                                 free_extent_buffer(left);
1996                         }
1997                         return 0;
1998                 }
1999                 btrfs_tree_unlock(left);
2000                 free_extent_buffer(left);
2001         }
2002         right = read_node_slot(root, parent, pslot + 1);
2003
2004         /*
2005          * then try to empty the right most buffer into the middle
2006          */
2007         if (right) {
2008                 u32 right_nr;
2009
2010                 btrfs_tree_lock(right);
2011                 btrfs_set_lock_blocking(right);
2012
2013                 right_nr = btrfs_header_nritems(right);
2014                 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
2015                         wret = 1;
2016                 } else {
2017                         ret = btrfs_cow_block(trans, root, right,
2018                                               parent, pslot + 1,
2019                                               &right);
2020                         if (ret)
2021                                 wret = 1;
2022                         else {
2023                                 wret = balance_node_right(trans, root,
2024                                                           right, mid);
2025                         }
2026                 }
2027                 if (wret < 0)
2028                         ret = wret;
2029                 if (wret == 0) {
2030                         struct btrfs_disk_key disk_key;
2031
2032                         btrfs_node_key(right, &disk_key, 0);
2033                         tree_mod_log_set_node_key(root->fs_info, parent,
2034                                                   &disk_key, pslot + 1, 0);
2035                         btrfs_set_node_key(parent, &disk_key, pslot + 1);
2036                         btrfs_mark_buffer_dirty(parent);
2037
2038                         if (btrfs_header_nritems(mid) <= orig_slot) {
2039                                 path->nodes[level] = right;
2040                                 path->slots[level + 1] += 1;
2041                                 path->slots[level] = orig_slot -
2042                                         btrfs_header_nritems(mid);
2043                                 btrfs_tree_unlock(mid);
2044                                 free_extent_buffer(mid);
2045                         } else {
2046                                 btrfs_tree_unlock(right);
2047                                 free_extent_buffer(right);
2048                         }
2049                         return 0;
2050                 }
2051                 btrfs_tree_unlock(right);
2052                 free_extent_buffer(right);
2053         }
2054         return 1;
2055 }
2056
2057 /*
2058  * readahead one full node of leaves, finding things that are close
2059  * to the block in 'slot', and triggering ra on them.
2060  */
2061 static void reada_for_search(struct btrfs_root *root,
2062                              struct btrfs_path *path,
2063                              int level, int slot, u64 objectid)
2064 {
2065         struct extent_buffer *node;
2066         struct btrfs_disk_key disk_key;
2067         u32 nritems;
2068         u64 search;
2069         u64 target;
2070         u64 nread = 0;
2071         u64 gen;
2072         int direction = path->reada;
2073         struct extent_buffer *eb;
2074         u32 nr;
2075         u32 blocksize;
2076         u32 nscan = 0;
2077
2078         if (level != 1)
2079                 return;
2080
2081         if (!path->nodes[level])
2082                 return;
2083
2084         node = path->nodes[level];
2085
2086         search = btrfs_node_blockptr(node, slot);
2087         blocksize = btrfs_level_size(root, level - 1);
2088         eb = btrfs_find_tree_block(root, search, blocksize);
2089         if (eb) {
2090                 free_extent_buffer(eb);
2091                 return;
2092         }
2093
2094         target = search;
2095
2096         nritems = btrfs_header_nritems(node);
2097         nr = slot;
2098
2099         while (1) {
2100                 if (direction < 0) {
2101                         if (nr == 0)
2102                                 break;
2103                         nr--;
2104                 } else if (direction > 0) {
2105                         nr++;
2106                         if (nr >= nritems)
2107                                 break;
2108                 }
2109                 if (path->reada < 0 && objectid) {
2110                         btrfs_node_key(node, &disk_key, nr);
2111                         if (btrfs_disk_key_objectid(&disk_key) != objectid)
2112                                 break;
2113                 }
2114                 search = btrfs_node_blockptr(node, nr);
2115                 if ((search <= target && target - search <= 65536) ||
2116                     (search > target && search - target <= 65536)) {
2117                         gen = btrfs_node_ptr_generation(node, nr);
2118                         readahead_tree_block(root, search, blocksize, gen);
2119                         nread += blocksize;
2120                 }
2121                 nscan++;
2122                 if ((nread > 65536 || nscan > 32))
2123                         break;
2124         }
2125 }
2126
2127 /*
2128  * returns -EAGAIN if it had to drop the path, or zero if everything was in
2129  * cache
2130  */
2131 static noinline int reada_for_balance(struct btrfs_root *root,
2132                                       struct btrfs_path *path, int level)
2133 {
2134         int slot;
2135         int nritems;
2136         struct extent_buffer *parent;
2137         struct extent_buffer *eb;
2138         u64 gen;
2139         u64 block1 = 0;
2140         u64 block2 = 0;
2141         int ret = 0;
2142         int blocksize;
2143
2144         parent = path->nodes[level + 1];
2145         if (!parent)
2146                 return 0;
2147
2148         nritems = btrfs_header_nritems(parent);
2149         slot = path->slots[level + 1];
2150         blocksize = btrfs_level_size(root, level);
2151
2152         if (slot > 0) {
2153                 block1 = btrfs_node_blockptr(parent, slot - 1);
2154                 gen = btrfs_node_ptr_generation(parent, slot - 1);
2155                 eb = btrfs_find_tree_block(root, block1, blocksize);
2156                 /*
2157                  * if we get -eagain from btrfs_buffer_uptodate, we
2158                  * don't want to return eagain here.  That will loop
2159                  * forever
2160                  */
2161                 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2162                         block1 = 0;
2163                 free_extent_buffer(eb);
2164         }
2165         if (slot + 1 < nritems) {
2166                 block2 = btrfs_node_blockptr(parent, slot + 1);
2167                 gen = btrfs_node_ptr_generation(parent, slot + 1);
2168                 eb = btrfs_find_tree_block(root, block2, blocksize);
2169                 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2170                         block2 = 0;
2171                 free_extent_buffer(eb);
2172         }
2173         if (block1 || block2) {
2174                 ret = -EAGAIN;
2175
2176                 /* release the whole path */
2177                 btrfs_release_path(path);
2178
2179                 /* read the blocks */
2180                 if (block1)
2181                         readahead_tree_block(root, block1, blocksize, 0);
2182                 if (block2)
2183                         readahead_tree_block(root, block2, blocksize, 0);
2184
2185                 if (block1) {
2186                         eb = read_tree_block(root, block1, blocksize, 0);
2187                         free_extent_buffer(eb);
2188                 }
2189                 if (block2) {
2190                         eb = read_tree_block(root, block2, blocksize, 0);
2191                         free_extent_buffer(eb);
2192                 }
2193         }
2194         return ret;
2195 }
2196
2197
2198 /*
2199  * when we walk down the tree, it is usually safe to unlock the higher layers
2200  * in the tree.  The exceptions are when our path goes through slot 0, because
2201  * operations on the tree might require changing key pointers higher up in the
2202  * tree.
2203  *
2204  * callers might also have set path->keep_locks, which tells this code to keep
2205  * the lock if the path points to the last slot in the block.  This is part of
2206  * walking through the tree, and selecting the next slot in the higher block.
2207  *
2208  * lowest_unlock sets the lowest level in the tree we're allowed to unlock.  so
2209  * if lowest_unlock is 1, level 0 won't be unlocked
2210  */
2211 static noinline void unlock_up(struct btrfs_path *path, int level,
2212                                int lowest_unlock, int min_write_lock_level,
2213                                int *write_lock_level)
2214 {
2215         int i;
2216         int skip_level = level;
2217         int no_skips = 0;
2218         struct extent_buffer *t;
2219
2220         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2221                 if (!path->nodes[i])
2222                         break;
2223                 if (!path->locks[i])
2224                         break;
2225                 if (!no_skips && path->slots[i] == 0) {
2226                         skip_level = i + 1;
2227                         continue;
2228                 }
2229                 if (!no_skips && path->keep_locks) {
2230                         u32 nritems;
2231                         t = path->nodes[i];
2232                         nritems = btrfs_header_nritems(t);
2233                         if (nritems < 1 || path->slots[i] >= nritems - 1) {
2234                                 skip_level = i + 1;
2235                                 continue;
2236                         }
2237                 }
2238                 if (skip_level < i && i >= lowest_unlock)
2239                         no_skips = 1;
2240
2241                 t = path->nodes[i];
2242                 if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
2243                         btrfs_tree_unlock_rw(t, path->locks[i]);
2244                         path->locks[i] = 0;
2245                         if (write_lock_level &&
2246                             i > min_write_lock_level &&
2247                             i <= *write_lock_level) {
2248                                 *write_lock_level = i - 1;
2249                         }
2250                 }
2251         }
2252 }
2253
2254 /*
2255  * This releases any locks held in the path starting at level and
2256  * going all the way up to the root.
2257  *
2258  * btrfs_search_slot will keep the lock held on higher nodes in a few
2259  * corner cases, such as COW of the block at slot zero in the node.  This
2260  * ignores those rules, and it should only be called when there are no
2261  * more updates to be done higher up in the tree.
2262  */
2263 noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
2264 {
2265         int i;
2266
2267         if (path->keep_locks)
2268                 return;
2269
2270         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2271                 if (!path->nodes[i])
2272                         continue;
2273                 if (!path->locks[i])
2274                         continue;
2275                 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
2276                 path->locks[i] = 0;
2277         }
2278 }
2279
2280 /*
2281  * helper function for btrfs_search_slot.  The goal is to find a block
2282  * in cache without setting the path to blocking.  If we find the block
2283  * we return zero and the path is unchanged.
2284  *
2285  * If we can't find the block, we set the path blocking and do some
2286  * reada.  -EAGAIN is returned and the search must be repeated.
2287  */
2288 static int
2289 read_block_for_search(struct btrfs_trans_handle *trans,
2290                        struct btrfs_root *root, struct btrfs_path *p,
2291                        struct extent_buffer **eb_ret, int level, int slot,
2292                        struct btrfs_key *key, u64 time_seq)
2293 {
2294         u64 blocknr;
2295         u64 gen;
2296         u32 blocksize;
2297         struct extent_buffer *b = *eb_ret;
2298         struct extent_buffer *tmp;
2299         int ret;
2300
2301         blocknr = btrfs_node_blockptr(b, slot);
2302         gen = btrfs_node_ptr_generation(b, slot);
2303         blocksize = btrfs_level_size(root, level - 1);
2304
2305         tmp = btrfs_find_tree_block(root, blocknr, blocksize);
2306         if (tmp) {
2307                 /* first we do an atomic uptodate check */
2308                 if (btrfs_buffer_uptodate(tmp, 0, 1) > 0) {
2309                         if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2310                                 /*
2311                                  * we found an up to date block without
2312                                  * sleeping, return
2313                                  * right away
2314                                  */
2315                                 *eb_ret = tmp;
2316                                 return 0;
2317                         }
2318                         /* the pages were up to date, but we failed
2319                          * the generation number check.  Do a full
2320                          * read for the generation number that is correct.
2321                          * We must do this without dropping locks so
2322                          * we can trust our generation number
2323                          */
2324                         free_extent_buffer(tmp);
2325                         btrfs_set_path_blocking(p);
2326
2327                         /* now we're allowed to do a blocking uptodate check */
2328                         tmp = read_tree_block(root, blocknr, blocksize, gen);
2329                         if (tmp && btrfs_buffer_uptodate(tmp, gen, 0) > 0) {
2330                                 *eb_ret = tmp;
2331                                 return 0;
2332                         }
2333                         free_extent_buffer(tmp);
2334                         btrfs_release_path(p);
2335                         return -EIO;
2336                 }
2337         }
2338
2339         /*
2340          * reduce lock contention at high levels
2341          * of the btree by dropping locks before
2342          * we read.  Don't release the lock on the current
2343          * level because we need to walk this node to figure
2344          * out which blocks to read.
2345          */
2346         btrfs_unlock_up_safe(p, level + 1);
2347         btrfs_set_path_blocking(p);
2348
2349         free_extent_buffer(tmp);
2350         if (p->reada)
2351                 reada_for_search(root, p, level, slot, key->objectid);
2352
2353         btrfs_release_path(p);
2354
2355         ret = -EAGAIN;
2356         tmp = read_tree_block(root, blocknr, blocksize, 0);
2357         if (tmp) {
2358                 /*
2359                  * If the read above didn't mark this buffer up to date,
2360                  * it will never end up being up to date.  Set ret to EIO now
2361                  * and give up so that our caller doesn't loop forever
2362                  * on our EAGAINs.
2363                  */
2364                 if (!btrfs_buffer_uptodate(tmp, 0, 0))
2365                         ret = -EIO;
2366                 free_extent_buffer(tmp);
2367         }
2368         return ret;
2369 }
2370
2371 /*
2372  * helper function for btrfs_search_slot.  This does all of the checks
2373  * for node-level blocks and does any balancing required based on
2374  * the ins_len.
2375  *
2376  * If no extra work was required, zero is returned.  If we had to
2377  * drop the path, -EAGAIN is returned and btrfs_search_slot must
2378  * start over
2379  */
2380 static int
2381 setup_nodes_for_search(struct btrfs_trans_handle *trans,
2382                        struct btrfs_root *root, struct btrfs_path *p,
2383                        struct extent_buffer *b, int level, int ins_len,
2384                        int *write_lock_level)
2385 {
2386         int ret;
2387         if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2388             BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
2389                 int sret;
2390
2391                 if (*write_lock_level < level + 1) {
2392                         *write_lock_level = level + 1;
2393                         btrfs_release_path(p);
2394                         goto again;
2395                 }
2396
2397                 sret = reada_for_balance(root, p, level);
2398                 if (sret)
2399                         goto again;
2400
2401                 btrfs_set_path_blocking(p);
2402                 sret = split_node(trans, root, p, level);
2403                 btrfs_clear_path_blocking(p, NULL, 0);
2404
2405                 BUG_ON(sret > 0);
2406                 if (sret) {
2407                         ret = sret;
2408                         goto done;
2409                 }
2410                 b = p->nodes[level];
2411         } else if (ins_len < 0 && btrfs_header_nritems(b) <
2412                    BTRFS_NODEPTRS_PER_BLOCK(root) / 2) {
2413                 int sret;
2414
2415                 if (*write_lock_level < level + 1) {
2416                         *write_lock_level = level + 1;
2417                         btrfs_release_path(p);
2418                         goto again;
2419                 }
2420
2421                 sret = reada_for_balance(root, p, level);
2422                 if (sret)
2423                         goto again;
2424
2425                 btrfs_set_path_blocking(p);
2426                 sret = balance_level(trans, root, p, level);
2427                 btrfs_clear_path_blocking(p, NULL, 0);
2428
2429                 if (sret) {
2430                         ret = sret;
2431                         goto done;
2432                 }
2433                 b = p->nodes[level];
2434                 if (!b) {
2435                         btrfs_release_path(p);
2436                         goto again;
2437                 }
2438                 BUG_ON(btrfs_header_nritems(b) == 1);
2439         }
2440         return 0;
2441
2442 again:
2443         ret = -EAGAIN;
2444 done:
2445         return ret;
2446 }
2447
2448 /*
2449  * look for key in the tree.  path is filled in with nodes along the way
2450  * if key is found, we return zero and you can find the item in the leaf
2451  * level of the path (level 0)
2452  *
2453  * If the key isn't found, the path points to the slot where it should
2454  * be inserted, and 1 is returned.  If there are other errors during the
2455  * search a negative error number is returned.
2456  *
2457  * if ins_len > 0, nodes and leaves will be split as we walk down the
2458  * tree.  if ins_len < 0, nodes will be merged as we walk down the tree (if
2459  * possible)
2460  */
2461 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
2462                       *root, struct btrfs_key *key, struct btrfs_path *p, int
2463                       ins_len, int cow)
2464 {
2465         struct extent_buffer *b;
2466         int slot;
2467         int ret;
2468         int err;
2469         int level;
2470         int lowest_unlock = 1;
2471         int root_lock;
2472         /* everything at write_lock_level or lower must be write locked */
2473         int write_lock_level = 0;
2474         u8 lowest_level = 0;
2475         int min_write_lock_level;
2476
2477         lowest_level = p->lowest_level;
2478         WARN_ON(lowest_level && ins_len > 0);
2479         WARN_ON(p->nodes[0] != NULL);
2480
2481         if (ins_len < 0) {
2482                 lowest_unlock = 2;
2483
2484                 /* when we are removing items, we might have to go up to level
2485                  * two as we update tree pointers  Make sure we keep write
2486                  * for those levels as well
2487                  */
2488                 write_lock_level = 2;
2489         } else if (ins_len > 0) {
2490                 /*
2491                  * for inserting items, make sure we have a write lock on
2492                  * level 1 so we can update keys
2493                  */
2494                 write_lock_level = 1;
2495         }
2496
2497         if (!cow)
2498                 write_lock_level = -1;
2499
2500         if (cow && (p->keep_locks || p->lowest_level))
2501                 write_lock_level = BTRFS_MAX_LEVEL;
2502
2503         min_write_lock_level = write_lock_level;
2504
2505 again:
2506         /*
2507          * we try very hard to do read locks on the root
2508          */
2509         root_lock = BTRFS_READ_LOCK;
2510         level = 0;
2511         if (p->search_commit_root) {
2512                 /*
2513                  * the commit roots are read only
2514                  * so we always do read locks
2515                  */
2516                 b = root->commit_root;
2517                 extent_buffer_get(b);
2518                 level = btrfs_header_level(b);
2519                 if (!p->skip_locking)
2520                         btrfs_tree_read_lock(b);
2521         } else {
2522                 if (p->skip_locking) {
2523                         b = btrfs_root_node(root);
2524                         level = btrfs_header_level(b);
2525                 } else {
2526                         /* we don't know the level of the root node
2527                          * until we actually have it read locked
2528                          */
2529                         b = btrfs_read_lock_root_node(root);
2530                         level = btrfs_header_level(b);
2531                         if (level <= write_lock_level) {
2532                                 /* whoops, must trade for write lock */
2533                                 btrfs_tree_read_unlock(b);
2534                                 free_extent_buffer(b);
2535                                 b = btrfs_lock_root_node(root);
2536                                 root_lock = BTRFS_WRITE_LOCK;
2537
2538                                 /* the level might have changed, check again */
2539                                 level = btrfs_header_level(b);
2540                         }
2541                 }
2542         }
2543         p->nodes[level] = b;
2544         if (!p->skip_locking)
2545                 p->locks[level] = root_lock;
2546
2547         while (b) {
2548                 level = btrfs_header_level(b);
2549
2550                 /*
2551                  * setup the path here so we can release it under lock
2552                  * contention with the cow code
2553                  */
2554                 if (cow) {
2555                         /*
2556                          * if we don't really need to cow this block
2557                          * then we don't want to set the path blocking,
2558                          * so we test it here
2559                          */
2560                         if (!should_cow_block(trans, root, b))
2561                                 goto cow_done;
2562
2563                         btrfs_set_path_blocking(p);
2564
2565                         /*
2566                          * must have write locks on this node and the
2567                          * parent
2568                          */
2569                         if (level + 1 > write_lock_level) {
2570                                 write_lock_level = level + 1;
2571                                 btrfs_release_path(p);
2572                                 goto again;
2573                         }
2574
2575                         err = btrfs_cow_block(trans, root, b,
2576                                               p->nodes[level + 1],
2577                                               p->slots[level + 1], &b);
2578                         if (err) {
2579                                 ret = err;
2580                                 goto done;
2581                         }
2582                 }
2583 cow_done:
2584                 BUG_ON(!cow && ins_len);
2585
2586                 p->nodes[level] = b;
2587                 btrfs_clear_path_blocking(p, NULL, 0);
2588
2589                 /*
2590                  * we have a lock on b and as long as we aren't changing
2591                  * the tree, there is no way to for the items in b to change.
2592                  * It is safe to drop the lock on our parent before we
2593                  * go through the expensive btree search on b.
2594                  *
2595                  * If cow is true, then we might be changing slot zero,
2596                  * which may require changing the parent.  So, we can't
2597                  * drop the lock until after we know which slot we're
2598                  * operating on.
2599                  */
2600                 if (!cow)
2601                         btrfs_unlock_up_safe(p, level + 1);
2602
2603                 ret = bin_search(b, key, level, &slot);
2604
2605                 if (level != 0) {
2606                         int dec = 0;
2607                         if (ret && slot > 0) {
2608                                 dec = 1;
2609                                 slot -= 1;
2610                         }
2611                         p->slots[level] = slot;
2612                         err = setup_nodes_for_search(trans, root, p, b, level,
2613                                              ins_len, &write_lock_level);
2614                         if (err == -EAGAIN)
2615                                 goto again;
2616                         if (err) {
2617                                 ret = err;
2618                                 goto done;
2619                         }
2620                         b = p->nodes[level];
2621                         slot = p->slots[level];
2622
2623                         /*
2624                          * slot 0 is special, if we change the key
2625                          * we have to update the parent pointer
2626                          * which means we must have a write lock
2627                          * on the parent
2628                          */
2629                         if (slot == 0 && cow &&
2630                             write_lock_level < level + 1) {
2631                                 write_lock_level = level + 1;
2632                                 btrfs_release_path(p);
2633                                 goto again;
2634                         }
2635
2636                         unlock_up(p, level, lowest_unlock,
2637                                   min_write_lock_level, &write_lock_level);
2638
2639                         if (level == lowest_level) {
2640                                 if (dec)
2641                                         p->slots[level]++;
2642                                 goto done;
2643                         }
2644
2645                         err = read_block_for_search(trans, root, p,
2646                                                     &b, level, slot, key, 0);
2647                         if (err == -EAGAIN)
2648                                 goto again;
2649                         if (err) {
2650                                 ret = err;
2651                                 goto done;
2652                         }
2653
2654                         if (!p->skip_locking) {
2655                                 level = btrfs_header_level(b);
2656                                 if (level <= write_lock_level) {
2657                                         err = btrfs_try_tree_write_lock(b);
2658                                         if (!err) {
2659                                                 btrfs_set_path_blocking(p);
2660                                                 btrfs_tree_lock(b);
2661                                                 btrfs_clear_path_blocking(p, b,
2662                                                                   BTRFS_WRITE_LOCK);
2663                                         }
2664                                         p->locks[level] = BTRFS_WRITE_LOCK;
2665                                 } else {
2666                                         err = btrfs_try_tree_read_lock(b);
2667                                         if (!err) {
2668                                                 btrfs_set_path_blocking(p);
2669                                                 btrfs_tree_read_lock(b);
2670                                                 btrfs_clear_path_blocking(p, b,
2671                                                                   BTRFS_READ_LOCK);
2672                                         }
2673                                         p->locks[level] = BTRFS_READ_LOCK;
2674                                 }
2675                                 p->nodes[level] = b;
2676                         }
2677                 } else {
2678                         p->slots[level] = slot;
2679                         if (ins_len > 0 &&
2680                             btrfs_leaf_free_space(root, b) < ins_len) {
2681                                 if (write_lock_level < 1) {
2682                                         write_lock_level = 1;
2683                                         btrfs_release_path(p);
2684                                         goto again;
2685                                 }
2686
2687                                 btrfs_set_path_blocking(p);
2688                                 err = split_leaf(trans, root, key,
2689                                                  p, ins_len, ret == 0);
2690                                 btrfs_clear_path_blocking(p, NULL, 0);
2691
2692                                 BUG_ON(err > 0);
2693                                 if (err) {
2694                                         ret = err;
2695                                         goto done;
2696                                 }
2697                         }
2698                         if (!p->search_for_split)
2699                                 unlock_up(p, level, lowest_unlock,
2700                                           min_write_lock_level, &write_lock_level);
2701                         goto done;
2702                 }
2703         }
2704         ret = 1;
2705 done:
2706         /*
2707          * we don't really know what they plan on doing with the path
2708          * from here on, so for now just mark it as blocking
2709          */
2710         if (!p->leave_spinning)
2711                 btrfs_set_path_blocking(p);
2712         if (ret < 0)
2713                 btrfs_release_path(p);
2714         return ret;
2715 }
2716
2717 /*
2718  * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2719  * current state of the tree together with the operations recorded in the tree
2720  * modification log to search for the key in a previous version of this tree, as
2721  * denoted by the time_seq parameter.
2722  *
2723  * Naturally, there is no support for insert, delete or cow operations.
2724  *
2725  * The resulting path and return value will be set up as if we called
2726  * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2727  */
2728 int btrfs_search_old_slot(struct btrfs_root *root, struct btrfs_key *key,
2729                           struct btrfs_path *p, u64 time_seq)
2730 {
2731         struct extent_buffer *b;
2732         int slot;
2733         int ret;
2734         int err;
2735         int level;
2736         int lowest_unlock = 1;
2737         u8 lowest_level = 0;
2738
2739         lowest_level = p->lowest_level;
2740         WARN_ON(p->nodes[0] != NULL);
2741
2742         if (p->search_commit_root) {
2743                 BUG_ON(time_seq);
2744                 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2745         }
2746
2747 again:
2748         b = get_old_root(root, time_seq);
2749         level = btrfs_header_level(b);
2750         p->locks[level] = BTRFS_READ_LOCK;
2751
2752         while (b) {
2753                 level = btrfs_header_level(b);
2754                 p->nodes[level] = b;
2755                 btrfs_clear_path_blocking(p, NULL, 0);
2756
2757                 /*
2758                  * we have a lock on b and as long as we aren't changing
2759                  * the tree, there is no way to for the items in b to change.
2760                  * It is safe to drop the lock on our parent before we
2761                  * go through the expensive btree search on b.
2762                  */
2763                 btrfs_unlock_up_safe(p, level + 1);
2764
2765                 ret = bin_search(b, key, level, &slot);
2766
2767                 if (level != 0) {
2768                         int dec = 0;
2769                         if (ret && slot > 0) {
2770                                 dec = 1;
2771                                 slot -= 1;
2772                         }
2773                         p->slots[level] = slot;
2774                         unlock_up(p, level, lowest_unlock, 0, NULL);
2775
2776                         if (level == lowest_level) {
2777                                 if (dec)
2778                                         p->slots[level]++;
2779                                 goto done;
2780                         }
2781
2782                         err = read_block_for_search(NULL, root, p, &b, level,
2783                                                     slot, key, time_seq);
2784                         if (err == -EAGAIN)
2785                                 goto again;
2786                         if (err) {
2787                                 ret = err;
2788                                 goto done;
2789                         }
2790
2791                         level = btrfs_header_level(b);
2792                         err = btrfs_try_tree_read_lock(b);
2793                         if (!err) {
2794                                 btrfs_set_path_blocking(p);
2795                                 btrfs_tree_read_lock(b);
2796                                 btrfs_clear_path_blocking(p, b,
2797                                                           BTRFS_READ_LOCK);
2798                         }
2799                         p->locks[level] = BTRFS_READ_LOCK;
2800                         p->nodes[level] = b;
2801                         b = tree_mod_log_rewind(root->fs_info, b, time_seq);
2802                         if (b != p->nodes[level]) {
2803                                 btrfs_tree_unlock_rw(p->nodes[level],
2804                                                      p->locks[level]);
2805                                 p->locks[level] = 0;
2806                                 p->nodes[level] = b;
2807                         }
2808                 } else {
2809                         p->slots[level] = slot;
2810                         unlock_up(p, level, lowest_unlock, 0, NULL);
2811                         goto done;
2812                 }
2813         }
2814         ret = 1;
2815 done:
2816         if (!p->leave_spinning)
2817                 btrfs_set_path_blocking(p);
2818         if (ret < 0)
2819                 btrfs_release_path(p);
2820
2821         return ret;
2822 }
2823
2824 /*
2825  * helper to use instead of search slot if no exact match is needed but
2826  * instead the next or previous item should be returned.
2827  * When find_higher is true, the next higher item is returned, the next lower
2828  * otherwise.
2829  * When return_any and find_higher are both true, and no higher item is found,
2830  * return the next lower instead.
2831  * When return_any is true and find_higher is false, and no lower item is found,
2832  * return the next higher instead.
2833  * It returns 0 if any item is found, 1 if none is found (tree empty), and
2834  * < 0 on error
2835  */
2836 int btrfs_search_slot_for_read(struct btrfs_root *root,
2837                                struct btrfs_key *key, struct btrfs_path *p,
2838                                int find_higher, int return_any)
2839 {
2840         int ret;
2841         struct extent_buffer *leaf;
2842
2843 again:
2844         ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
2845         if (ret <= 0)
2846                 return ret;
2847         /*
2848          * a return value of 1 means the path is at the position where the
2849          * item should be inserted. Normally this is the next bigger item,
2850          * but in case the previous item is the last in a leaf, path points
2851          * to the first free slot in the previous leaf, i.e. at an invalid
2852          * item.
2853          */
2854         leaf = p->nodes[0];
2855
2856         if (find_higher) {
2857                 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
2858                         ret = btrfs_next_leaf(root, p);
2859                         if (ret <= 0)
2860                                 return ret;
2861                         if (!return_any)
2862                                 return 1;
2863                         /*
2864                          * no higher item found, return the next
2865                          * lower instead
2866                          */
2867                         return_any = 0;
2868                         find_higher = 0;
2869                         btrfs_release_path(p);
2870                         goto again;
2871                 }
2872         } else {
2873                 if (p->slots[0] == 0) {
2874                         ret = btrfs_prev_leaf(root, p);
2875                         if (ret < 0)
2876                                 return ret;
2877                         if (!ret) {
2878                                 p->slots[0] = btrfs_header_nritems(leaf) - 1;
2879                                 return 0;
2880                         }
2881                         if (!return_any)
2882                                 return 1;
2883                         /*
2884                          * no lower item found, return the next
2885                          * higher instead
2886                          */
2887                         return_any = 0;
2888                         find_higher = 1;
2889                         btrfs_release_path(p);
2890                         goto again;
2891                 } else {
2892                         --p->slots[0];
2893                 }
2894         }
2895         return 0;
2896 }
2897
2898 /*
2899  * adjust the pointers going up the tree, starting at level
2900  * making sure the right key of each node is points to 'key'.
2901  * This is used after shifting pointers to the left, so it stops
2902  * fixing up pointers when a given leaf/node is not in slot 0 of the
2903  * higher levels
2904  *
2905  */
2906 static void fixup_low_keys(struct btrfs_trans_handle *trans,
2907                            struct btrfs_root *root, struct btrfs_path *path,
2908                            struct btrfs_disk_key *key, int level)
2909 {
2910         int i;
2911         struct extent_buffer *t;
2912
2913         for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2914                 int tslot = path->slots[i];
2915                 if (!path->nodes[i])
2916                         break;
2917                 t = path->nodes[i];
2918                 tree_mod_log_set_node_key(root->fs_info, t, key, tslot, 1);
2919                 btrfs_set_node_key(t, key, tslot);
2920                 btrfs_mark_buffer_dirty(path->nodes[i]);
2921                 if (tslot != 0)
2922                         break;
2923         }
2924 }
2925
2926 /*
2927  * update item key.
2928  *
2929  * This function isn't completely safe. It's the caller's responsibility
2930  * that the new key won't break the order
2931  */
2932 void btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
2933                              struct btrfs_root *root, struct btrfs_path *path,
2934                              struct btrfs_key *new_key)
2935 {
2936         struct btrfs_disk_key disk_key;
2937         struct extent_buffer *eb;
2938         int slot;
2939
2940         eb = path->nodes[0];
2941         slot = path->slots[0];
2942         if (slot > 0) {
2943                 btrfs_item_key(eb, &disk_key, slot - 1);
2944                 BUG_ON(comp_keys(&disk_key, new_key) >= 0);
2945         }
2946         if (slot < btrfs_header_nritems(eb) - 1) {
2947                 btrfs_item_key(eb, &disk_key, slot + 1);
2948                 BUG_ON(comp_keys(&disk_key, new_key) <= 0);
2949         }
2950
2951         btrfs_cpu_key_to_disk(&disk_key, new_key);
2952         btrfs_set_item_key(eb, &disk_key, slot);
2953         btrfs_mark_buffer_dirty(eb);
2954         if (slot == 0)
2955                 fixup_low_keys(trans, root, path, &disk_key, 1);
2956 }
2957
2958 /*
2959  * try to push data from one node into the next node left in the
2960  * tree.
2961  *
2962  * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2963  * error, and > 0 if there was no room in the left hand block.
2964  */
2965 static int push_node_left(struct btrfs_trans_handle *trans,
2966                           struct btrfs_root *root, struct extent_buffer *dst,
2967                           struct extent_buffer *src, int empty)
2968 {
2969         int push_items = 0;
2970         int src_nritems;
2971         int dst_nritems;
2972         int ret = 0;
2973
2974         src_nritems = btrfs_header_nritems(src);
2975         dst_nritems = btrfs_header_nritems(dst);
2976         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
2977         WARN_ON(btrfs_header_generation(src) != trans->transid);
2978         WARN_ON(btrfs_header_generation(dst) != trans->transid);
2979
2980         if (!empty && src_nritems <= 8)
2981                 return 1;
2982
2983         if (push_items <= 0)
2984                 return 1;
2985
2986         if (empty) {
2987                 push_items = min(src_nritems, push_items);
2988                 if (push_items < src_nritems) {
2989                         /* leave at least 8 pointers in the node if
2990                          * we aren't going to empty it
2991                          */
2992                         if (src_nritems - push_items < 8) {
2993                                 if (push_items <= 8)
2994                                         return 1;
2995                                 push_items -= 8;
2996                         }
2997                 }
2998         } else
2999                 push_items = min(src_nritems - 8, push_items);
3000
3001         tree_mod_log_eb_copy(root->fs_info, dst, src, dst_nritems, 0,
3002                              push_items);
3003         copy_extent_buffer(dst, src,
3004                            btrfs_node_key_ptr_offset(dst_nritems),
3005                            btrfs_node_key_ptr_offset(0),
3006                            push_items * sizeof(struct btrfs_key_ptr));
3007
3008         if (push_items < src_nritems) {
3009                 /*
3010                  * don't call tree_mod_log_eb_move here, key removal was already
3011                  * fully logged by tree_mod_log_eb_copy above.
3012                  */
3013                 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
3014                                       btrfs_node_key_ptr_offset(push_items),
3015                                       (src_nritems - push_items) *
3016                                       sizeof(struct btrfs_key_ptr));
3017         }
3018         btrfs_set_header_nritems(src, src_nritems - push_items);
3019         btrfs_set_header_nritems(dst, dst_nritems + push_items);
3020         btrfs_mark_buffer_dirty(src);
3021         btrfs_mark_buffer_dirty(dst);
3022
3023         return ret;
3024 }
3025
3026 /*
3027  * try to push data from one node into the next node right in the
3028  * tree.
3029  *
3030  * returns 0 if some ptrs were pushed, < 0 if there was some horrible
3031  * error, and > 0 if there was no room in the right hand block.
3032  *
3033  * this will  only push up to 1/2 the contents of the left node over
3034  */
3035 static int balance_node_right(struct btrfs_trans_handle *trans,
3036                               struct btrfs_root *root,
3037                               struct extent_buffer *dst,
3038                               struct extent_buffer *src)
3039 {
3040         int push_items = 0;
3041         int max_push;
3042         int src_nritems;
3043         int dst_nritems;
3044         int ret = 0;
3045
3046         WARN_ON(btrfs_header_generation(src) != trans->transid);
3047         WARN_ON(btrfs_header_generation(dst) != trans->transid);
3048
3049         src_nritems = btrfs_header_nritems(src);
3050         dst_nritems = btrfs_header_nritems(dst);
3051         push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
3052         if (push_items <= 0)
3053                 return 1;
3054
3055         if (src_nritems < 4)
3056                 return 1;
3057
3058         max_push = src_nritems / 2 + 1;
3059         /* don't try to empty the node */
3060         if (max_push >= src_nritems)
3061                 return 1;
3062
3063         if (max_push < push_items)
3064                 push_items = max_push;
3065
3066         tree_mod_log_eb_move(root->fs_info, dst, push_items, 0, dst_nritems);
3067         memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
3068                                       btrfs_node_key_ptr_offset(0),
3069                                       (dst_nritems) *
3070                                       sizeof(struct btrfs_key_ptr));
3071
3072         tree_mod_log_eb_copy(root->fs_info, dst, src, 0,
3073                              src_nritems - push_items, push_items);
3074         copy_extent_buffer(dst, src,
3075                            btrfs_node_key_ptr_offset(0),
3076                            btrfs_node_key_ptr_offset(src_nritems - push_items),
3077                            push_items * sizeof(struct btrfs_key_ptr));
3078
3079         btrfs_set_header_nritems(src, src_nritems - push_items);
3080         btrfs_set_header_nritems(dst, dst_nritems + push_items);
3081
3082         btrfs_mark_buffer_dirty(src);
3083         btrfs_mark_buffer_dirty(dst);
3084
3085         return ret;
3086 }
3087
3088 /*
3089  * helper function to insert a new root level in the tree.
3090  * A new node is allocated, and a single item is inserted to
3091  * point to the existing root
3092  *
3093  * returns zero on success or < 0 on failure.
3094  */
3095 static noinline int insert_new_root(struct btrfs_trans_handle *trans,
3096                            struct btrfs_root *root,
3097                            struct btrfs_path *path, int level)
3098 {
3099         u64 lower_gen;
3100         struct extent_buffer *lower;
3101         struct extent_buffer *c;
3102         struct extent_buffer *old;
3103         struct btrfs_disk_key lower_key;
3104
3105         BUG_ON(path->nodes[level]);
3106         BUG_ON(path->nodes[level-1] != root->node);
3107
3108         lower = path->nodes[level-1];
3109         if (level == 1)
3110                 btrfs_item_key(lower, &lower_key, 0);
3111         else
3112                 btrfs_node_key(lower, &lower_key, 0);
3113
3114         c = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
3115                                    root->root_key.objectid, &lower_key,
3116                                    level, root->node->start, 0);
3117         if (IS_ERR(c))
3118                 return PTR_ERR(c);
3119
3120         root_add_used(root, root->nodesize);
3121
3122         memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
3123         btrfs_set_header_nritems(c, 1);
3124         btrfs_set_header_level(c, level);
3125         btrfs_set_header_bytenr(c, c->start);
3126         btrfs_set_header_generation(c, trans->transid);
3127         btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
3128         btrfs_set_header_owner(c, root->root_key.objectid);
3129
3130         write_extent_buffer(c, root->fs_info->fsid,
3131                             (unsigned long)btrfs_header_fsid(c),
3132                             BTRFS_FSID_SIZE);
3133
3134         write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
3135                             (unsigned long)btrfs_header_chunk_tree_uuid(c),
3136                             BTRFS_UUID_SIZE);
3137
3138         btrfs_set_node_key(c, &lower_key, 0);
3139         btrfs_set_node_blockptr(c, 0, lower->start);
3140         lower_gen = btrfs_header_generation(lower);
3141         WARN_ON(lower_gen != trans->transid);
3142
3143         btrfs_set_node_ptr_generation(c, 0, lower_gen);
3144
3145         btrfs_mark_buffer_dirty(c);
3146
3147         old = root->node;
3148         tree_mod_log_set_root_pointer(root, c);
3149         rcu_assign_pointer(root->node, c);
3150
3151         /* the super has an extra ref to root->node */
3152         free_extent_buffer(old);
3153
3154         add_root_to_dirty_list(root);
3155         extent_buffer_get(c);
3156         path->nodes[level] = c;
3157         path->locks[level] = BTRFS_WRITE_LOCK;
3158         path->slots[level] = 0;
3159         return 0;
3160 }
3161
3162 /*
3163  * worker function to insert a single pointer in a node.
3164  * the node should have enough room for the pointer already
3165  *
3166  * slot and level indicate where you want the key to go, and
3167  * blocknr is the block the key points to.
3168  */
3169 static void insert_ptr(struct btrfs_trans_handle *trans,
3170                        struct btrfs_root *root, struct btrfs_path *path,
3171                        struct btrfs_disk_key *key, u64 bytenr,
3172                        int slot, int level)
3173 {
3174         struct extent_buffer *lower;
3175         int nritems;
3176         int ret;
3177
3178         BUG_ON(!path->nodes[level]);
3179         btrfs_assert_tree_locked(path->nodes[level]);
3180         lower = path->nodes[level];
3181         nritems = btrfs_header_nritems(lower);
3182         BUG_ON(slot > nritems);
3183         BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(root));
3184         if (slot != nritems) {
3185                 if (level)
3186                         tree_mod_log_eb_move(root->fs_info, lower, slot + 1,
3187                                              slot, nritems - slot);
3188                 memmove_extent_buffer(lower,
3189                               btrfs_node_key_ptr_offset(slot + 1),
3190                               btrfs_node_key_ptr_offset(slot),
3191                               (nritems - slot) * sizeof(struct btrfs_key_ptr));
3192         }
3193         if (level) {
3194                 ret = tree_mod_log_insert_key(root->fs_info, lower, slot,
3195                                               MOD_LOG_KEY_ADD);
3196                 BUG_ON(ret < 0);
3197         }
3198         btrfs_set_node_key(lower, key, slot);
3199         btrfs_set_node_blockptr(lower, slot, bytenr);
3200         WARN_ON(trans->transid == 0);
3201         btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3202         btrfs_set_header_nritems(lower, nritems + 1);
3203         btrfs_mark_buffer_dirty(lower);
3204 }
3205
3206 /*
3207  * split the node at the specified level in path in two.
3208  * The path is corrected to point to the appropriate node after the split
3209  *
3210  * Before splitting this tries to make some room in the node by pushing
3211  * left and right, if either one works, it returns right away.
3212  *
3213  * returns 0 on success and < 0 on failure
3214  */
3215 static noinline int split_node(struct btrfs_trans_handle *trans,
3216                                struct btrfs_root *root,
3217                                struct btrfs_path *path, int level)
3218 {
3219         struct extent_buffer *c;
3220         struct extent_buffer *split;
3221         struct btrfs_disk_key disk_key;
3222         int mid;
3223         int ret;
3224         u32 c_nritems;
3225
3226         c = path->nodes[level];
3227         WARN_ON(btrfs_header_generation(c) != trans->transid);
3228         if (c == root->node) {
3229                 /* trying to split the root, lets make a new one */
3230                 ret = insert_new_root(trans, root, path, level + 1);
3231                 if (ret)
3232                         return ret;
3233         } else {
3234                 ret = push_nodes_for_insert(trans, root, path, level);
3235                 c = path->nodes[level];
3236                 if (!ret && btrfs_header_nritems(c) <
3237                     BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
3238                         return 0;
3239                 if (ret < 0)
3240                         return ret;
3241         }
3242
3243         c_nritems = btrfs_header_nritems(c);
3244         mid = (c_nritems + 1) / 2;
3245         btrfs_node_key(c, &disk_key, mid);
3246
3247         split = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
3248                                         root->root_key.objectid,
3249                                         &disk_key, level, c->start, 0);
3250         if (IS_ERR(split))
3251                 return PTR_ERR(split);
3252
3253         root_add_used(root, root->nodesize);
3254
3255         memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header));
3256         btrfs_set_header_level(split, btrfs_header_level(c));
3257         btrfs_set_header_bytenr(split, split->start);
3258         btrfs_set_header_generation(split, trans->transid);
3259         btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
3260         btrfs_set_header_owner(split, root->root_key.objectid);
3261         write_extent_buffer(split, root->fs_info->fsid,
3262                             (unsigned long)btrfs_header_fsid(split),
3263                             BTRFS_FSID_SIZE);
3264         write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
3265                             (unsigned long)btrfs_header_chunk_tree_uuid(split),
3266                             BTRFS_UUID_SIZE);
3267
3268         tree_mod_log_eb_copy(root->fs_info, split, c, 0, mid, c_nritems - mid);
3269         copy_extent_buffer(split, c,
3270                            btrfs_node_key_ptr_offset(0),
3271                            btrfs_node_key_ptr_offset(mid),
3272                            (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3273         btrfs_set_header_nritems(split, c_nritems - mid);
3274         btrfs_set_header_nritems(c, mid);
3275         ret = 0;
3276
3277         btrfs_mark_buffer_dirty(c);
3278         btrfs_mark_buffer_dirty(split);
3279
3280         insert_ptr(trans, root, path, &disk_key, split->start,
3281                    path->slots[level + 1] + 1, level + 1);
3282
3283         if (path->slots[level] >= mid) {
3284                 path->slots[level] -= mid;
3285                 btrfs_tree_unlock(c);
3286                 free_extent_buffer(c);
3287                 path->nodes[level] = split;
3288                 path->slots[level + 1] += 1;
3289         } else {
3290                 btrfs_tree_unlock(split);
3291                 free_extent_buffer(split);
3292         }
3293         return ret;
3294 }
3295
3296 /*
3297  * how many bytes are required to store the items in a leaf.  start
3298  * and nr indicate which items in the leaf to check.  This totals up the
3299  * space used both by the item structs and the item data
3300  */
3301 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3302 {
3303         int data_len;
3304         int nritems = btrfs_header_nritems(l);
3305         int end = min(nritems, start + nr) - 1;
3306
3307         if (!nr)
3308                 return 0;
3309         data_len = btrfs_item_end_nr(l, start);
3310         data_len = data_len - btrfs_item_offset_nr(l, end);
3311         data_len += sizeof(struct btrfs_item) * nr;
3312         WARN_ON(data_len < 0);
3313         return data_len;
3314 }
3315
3316 /*
3317  * The space between the end of the leaf items and
3318  * the start of the leaf data.  IOW, how much room
3319  * the leaf has left for both items and data
3320  */
3321 noinline int btrfs_leaf_free_space(struct btrfs_root *root,
3322                                    struct extent_buffer *leaf)
3323 {
3324         int nritems = btrfs_header_nritems(leaf);
3325         int ret;
3326         ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
3327         if (ret < 0) {
3328                 printk(KERN_CRIT "leaf free space ret %d, leaf data size %lu, "
3329                        "used %d nritems %d\n",
3330                        ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
3331                        leaf_space_used(leaf, 0, nritems), nritems);
3332         }
3333         return ret;
3334 }
3335
3336 /*
3337  * min slot controls the lowest index we're willing to push to the
3338  * right.  We'll push up to and including min_slot, but no lower
3339  */
3340 static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
3341                                       struct btrfs_root *root,
3342                                       struct btrfs_path *path,
3343                                       int data_size, int empty,
3344                                       struct extent_buffer *right,
3345                                       int free_space, u32 left_nritems,
3346                                       u32 min_slot)
3347 {
3348         struct extent_buffer *left = path->nodes[0];
3349         struct extent_buffer *upper = path->nodes[1];
3350         struct btrfs_map_token token;
3351         struct btrfs_disk_key disk_key;
3352         int slot;
3353         u32 i;
3354         int push_space = 0;
3355         int push_items = 0;
3356         struct btrfs_item *item;
3357         u32 nr;
3358         u32 right_nritems;
3359         u32 data_end;
3360         u32 this_item_size;
3361
3362         btrfs_init_map_token(&token);
3363
3364         if (empty)
3365                 nr = 0;
3366         else
3367                 nr = max_t(u32, 1, min_slot);
3368
3369         if (path->slots[0] >= left_nritems)
3370                 push_space += data_size;
3371
3372         slot = path->slots[1];
3373         i = left_nritems - 1;
3374         while (i >= nr) {
3375                 item = btrfs_item_nr(left, i);
3376
3377                 if (!empty && push_items > 0) {
3378                         if (path->slots[0] > i)
3379                                 break;
3380                         if (path->slots[0] == i) {
3381                                 int space = btrfs_leaf_free_space(root, left);
3382                                 if (space + push_space * 2 > free_space)
3383                                         break;
3384                         }
3385                 }
3386
3387                 if (path->slots[0] == i)
3388                         push_space += data_size;
3389
3390                 this_item_size = btrfs_item_size(left, item);
3391                 if (this_item_size + sizeof(*item) + push_space > free_space)
3392                         break;
3393
3394                 push_items++;
3395                 push_space += this_item_size + sizeof(*item);
3396                 if (i == 0)
3397                         break;
3398                 i--;
3399         }
3400
3401         if (push_items == 0)
3402                 goto out_unlock;
3403
3404         if (!empty && push_items == left_nritems)
3405                 WARN_ON(1);
3406
3407         /* push left to right */
3408         right_nritems = btrfs_header_nritems(right);
3409
3410         push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3411         push_space -= leaf_data_end(root, left);
3412
3413         /* make room in the right data area */
3414         data_end = leaf_data_end(root, right);
3415         memmove_extent_buffer(right,
3416                               btrfs_leaf_data(right) + data_end - push_space,
3417                               btrfs_leaf_data(right) + data_end,
3418                               BTRFS_LEAF_DATA_SIZE(root) - data_end);
3419
3420         /* copy from the left data area */
3421         copy_extent_buffer(right, left, btrfs_leaf_data(right) +
3422                      BTRFS_LEAF_DATA_SIZE(root) - push_space,
3423                      btrfs_leaf_data(left) + leaf_data_end(root, left),
3424                      push_space);
3425
3426         memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3427                               btrfs_item_nr_offset(0),
3428                               right_nritems * sizeof(struct btrfs_item));
3429
3430         /* copy the items from left to right */
3431         copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3432                    btrfs_item_nr_offset(left_nritems - push_items),
3433                    push_items * sizeof(struct btrfs_item));
3434
3435         /* update the item pointers */
3436         right_nritems += push_items;
3437         btrfs_set_header_nritems(right, right_nritems);
3438         push_space = BTRFS_LEAF_DATA_SIZE(root);
3439         for (i = 0; i < right_nritems; i++) {
3440                 item = btrfs_item_nr(right, i);
3441                 push_space -= btrfs_token_item_size(right, item, &token);
3442                 btrfs_set_token_item_offset(right, item, push_space, &token);
3443         }
3444
3445         left_nritems -= push_items;
3446         btrfs_set_header_nritems(left, left_nritems);
3447
3448         if (left_nritems)
3449                 btrfs_mark_buffer_dirty(left);
3450         else
3451                 clean_tree_block(trans, root, left);
3452
3453         btrfs_mark_buffer_dirty(right);
3454
3455         btrfs_item_key(right, &disk_key, 0);
3456         btrfs_set_node_key(upper, &disk_key, slot + 1);
3457         btrfs_mark_buffer_dirty(upper);
3458
3459         /* then fixup the leaf pointer in the path */
3460         if (path->slots[0] >= left_nritems) {
3461                 path->slots[0] -= left_nritems;
3462                 if (btrfs_header_nritems(path->nodes[0]) == 0)
3463                         clean_tree_block(trans, root, path->nodes[0]);
3464                 btrfs_tree_unlock(path->nodes[0]);
3465                 free_extent_buffer(path->nodes[0]);
3466                 path->nodes[0] = right;
3467                 path->slots[1] += 1;
3468         } else {
3469                 btrfs_tree_unlock(right);
3470                 free_extent_buffer(right);
3471         }
3472         return 0;
3473
3474 out_unlock:
3475         btrfs_tree_unlock(right);
3476         free_extent_buffer(right);
3477         return 1;
3478 }
3479
3480 /*
3481  * push some data in the path leaf to the right, trying to free up at
3482  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3483  *
3484  * returns 1 if the push failed because the other node didn't have enough
3485  * room, 0 if everything worked out and < 0 if there were major errors.
3486  *
3487  * this will push starting from min_slot to the end of the leaf.  It won't
3488  * push any slot lower than min_slot
3489  */
3490 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3491                            *root, struct btrfs_path *path,
3492                            int min_data_size, int data_size,
3493                            int empty, u32 min_slot)
3494 {
3495         struct extent_buffer *left = path->nodes[0];
3496         struct extent_buffer *right;
3497         struct extent_buffer *upper;
3498         int slot;
3499         int free_space;
3500         u32 left_nritems;
3501         int ret;
3502
3503         if (!path->nodes[1])
3504                 return 1;
3505
3506         slot = path->slots[1];
3507         upper = path->nodes[1];
3508         if (slot >= btrfs_header_nritems(upper) - 1)
3509                 return 1;
3510
3511         btrfs_assert_tree_locked(path->nodes[1]);
3512
3513         right = read_node_slot(root, upper, slot + 1);
3514         if (right == NULL)
3515                 return 1;
3516
3517         btrfs_tree_lock(right);
3518         btrfs_set_lock_blocking(right);
3519
3520         free_space = btrfs_leaf_free_space(root, right);
3521         if (free_space < data_size)
3522                 goto out_unlock;
3523
3524         /* cow and double check */
3525         ret = btrfs_cow_block(trans, root, right, upper,
3526                               slot + 1, &right);
3527         if (ret)
3528                 goto out_unlock;
3529
3530         free_space = btrfs_leaf_free_space(root, right);
3531         if (free_space < data_size)
3532                 goto out_unlock;
3533
3534         left_nritems = btrfs_header_nritems(left);
3535         if (left_nritems == 0)
3536                 goto out_unlock;
3537
3538         return __push_leaf_right(trans, root, path, min_data_size, empty,
3539                                 right, free_space, left_nritems, min_slot);
3540 out_unlock:
3541         btrfs_tree_unlock(right);
3542         free_extent_buffer(right);
3543         return 1;
3544 }
3545
3546 /*
3547  * push some data in the path leaf to the left, trying to free up at
3548  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3549  *
3550  * max_slot can put a limit on how far into the leaf we'll push items.  The
3551  * item at 'max_slot' won't be touched.  Use (u32)-1 to make us do all the
3552  * items
3553  */
3554 static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
3555                                      struct btrfs_root *root,
3556                                      struct btrfs_path *path, int data_size,
3557                                      int empty, struct extent_buffer *left,
3558                                      int free_space, u32 right_nritems,
3559                                      u32 max_slot)
3560 {
3561         struct btrfs_disk_key disk_key;
3562         struct extent_buffer *right = path->nodes[0];
3563         int i;
3564         int push_space = 0;
3565         int push_items = 0;
3566         struct btrfs_item *item;
3567         u32 old_left_nritems;
3568         u32 nr;
3569         int ret = 0;
3570         u32 this_item_size;
3571         u32 old_left_item_size;
3572         struct btrfs_map_token token;
3573
3574         btrfs_init_map_token(&token);
3575
3576         if (empty)
3577                 nr = min(right_nritems, max_slot);
3578         else
3579                 nr = min(right_nritems - 1, max_slot);
3580
3581         for (i = 0; i < nr; i++) {
3582                 item = btrfs_item_nr(right, i);
3583
3584                 if (!empty && push_items > 0) {
3585                         if (path->slots[0] < i)
3586                                 break;
3587                         if (path->slots[0] == i) {
3588                                 int space = btrfs_leaf_free_space(root, right);
3589                                 if (space + push_space * 2 > free_space)
3590                                         break;
3591                         }
3592                 }
3593
3594                 if (path->slots[0] == i)
3595                         push_space += data_size;
3596
3597                 this_item_size = btrfs_item_size(right, item);
3598                 if (this_item_size + sizeof(*item) + push_space > free_space)
3599                         break;
3600
3601                 push_items++;
3602                 push_space += this_item_size + sizeof(*item);
3603         }
3604
3605         if (push_items == 0) {
3606                 ret = 1;
3607                 goto out;
3608         }
3609         if (!empty && push_items == btrfs_header_nritems(right))
3610                 WARN_ON(1);
3611
3612         /* push data from right to left */
3613         copy_extent_buffer(left, right,
3614                            btrfs_item_nr_offset(btrfs_header_nritems(left)),
3615                            btrfs_item_nr_offset(0),
3616                            push_items * sizeof(struct btrfs_item));
3617
3618         push_space = BTRFS_LEAF_DATA_SIZE(root) -
3619                      btrfs_item_offset_nr(right, push_items - 1);
3620
3621         copy_extent_buffer(left, right, btrfs_leaf_data(left) +
3622                      leaf_data_end(root, left) - push_space,
3623                      btrfs_leaf_data(right) +
3624                      btrfs_item_offset_nr(right, push_items - 1),
3625                      push_space);
3626         old_left_nritems = btrfs_header_nritems(left);
3627         BUG_ON(old_left_nritems <= 0);
3628
3629         old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3630         for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3631                 u32 ioff;
3632
3633                 item = btrfs_item_nr(left, i);
3634
3635                 ioff = btrfs_token_item_offset(left, item, &token);
3636                 btrfs_set_token_item_offset(left, item,
3637                       ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size),
3638                       &token);
3639         }
3640         btrfs_set_header_nritems(left, old_left_nritems + push_items);
3641
3642         /* fixup right node */
3643         if (push_items > right_nritems) {
3644                 printk(KERN_CRIT "push items %d nr %u\n", push_items,
3645                        right_nritems);
3646                 WARN_ON(1);
3647         }
3648
3649         if (push_items < right_nritems) {
3650                 push_space = btrfs_item_offset_nr(right, push_items - 1) -
3651                                                   leaf_data_end(root, right);
3652                 memmove_extent_buffer(right, btrfs_leaf_data(right) +
3653                                       BTRFS_LEAF_DATA_SIZE(root) - push_space,
3654                                       btrfs_leaf_data(right) +
3655                                       leaf_data_end(root, right), push_space);
3656
3657                 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3658                               btrfs_item_nr_offset(push_items),
3659                              (btrfs_header_nritems(right) - push_items) *
3660                              sizeof(struct btrfs_item));
3661         }
3662         right_nritems -= push_items;
3663         btrfs_set_header_nritems(right, right_nritems);
3664         push_space = BTRFS_LEAF_DATA_SIZE(root);
3665         for (i = 0; i < right_nritems; i++) {
3666                 item = btrfs_item_nr(right, i);
3667
3668                 push_space = push_space - btrfs_token_item_size(right,
3669                                                                 item, &token);
3670                 btrfs_set_token_item_offset(right, item, push_space, &token);
3671         }
3672
3673         btrfs_mark_buffer_dirty(left);
3674         if (right_nritems)
3675                 btrfs_mark_buffer_dirty(right);
3676         else
3677                 clean_tree_block(trans, root, right);
3678
3679         btrfs_item_key(right, &disk_key, 0);
3680         fixup_low_keys(trans, root, path, &disk_key, 1);
3681
3682         /* then fixup the leaf pointer in the path */
3683         if (path->slots[0] < push_items) {
3684                 path->slots[0] += old_left_nritems;
3685                 btrfs_tree_unlock(path->nodes[0]);
3686                 free_extent_buffer(path->nodes[0]);
3687                 path->nodes[0] = left;
3688                 path->slots[1] -= 1;
3689         } else {
3690                 btrfs_tree_unlock(left);
3691                 free_extent_buffer(left);
3692                 path->slots[0] -= push_items;
3693         }
3694         BUG_ON(path->slots[0] < 0);
3695         return ret;
3696 out:
3697         btrfs_tree_unlock(left);
3698         free_extent_buffer(left);
3699         return ret;
3700 }
3701
3702 /*
3703  * push some data in the path leaf to the left, trying to free up at
3704  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
3705  *
3706  * max_slot can put a limit on how far into the leaf we'll push items.  The
3707  * item at 'max_slot' won't be touched.  Use (u32)-1 to make us push all the
3708  * items
3709  */
3710 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3711                           *root, struct btrfs_path *path, int min_data_size,
3712                           int data_size, int empty, u32 max_slot)
3713 {
3714         struct extent_buffer *right = path->nodes[0];
3715         struct extent_buffer *left;
3716         int slot;
3717         int free_space;
3718         u32 right_nritems;
3719         int ret = 0;
3720
3721         slot = path->slots[1];
3722         if (slot == 0)
3723                 return 1;
3724         if (!path->nodes[1])
3725                 return 1;
3726
3727         right_nritems = btrfs_header_nritems(right);
3728         if (right_nritems == 0)
3729                 return 1;
3730
3731         btrfs_assert_tree_locked(path->nodes[1]);
3732
3733         left = read_node_slot(root, path->nodes[1], slot - 1);
3734         if (left == NULL)
3735                 return 1;
3736
3737         btrfs_tree_lock(left);
3738         btrfs_set_lock_blocking(left);
3739
3740         free_space = btrfs_leaf_free_space(root, left);
3741         if (free_space < data_size) {
3742                 ret = 1;
3743                 goto out;
3744         }
3745
3746         /* cow and double check */
3747         ret = btrfs_cow_block(trans, root, left,
3748                               path->nodes[1], slot - 1, &left);
3749         if (ret) {
3750                 /* we hit -ENOSPC, but it isn't fatal here */
3751                 if (ret == -ENOSPC)
3752                         ret = 1;
3753                 goto out;
3754         }
3755
3756         free_space = btrfs_leaf_free_space(root, left);
3757         if (free_space < data_size) {
3758                 ret = 1;
3759                 goto out;
3760         }
3761