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