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