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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007,2008 Oracle. All rights reserved.
4 */
5
6#include <linux/sched.h>
7#include <linux/slab.h>
8#include <linux/rbtree.h>
9#include <linux/mm.h>
10#include "ctree.h"
11#include "disk-io.h"
12#include "transaction.h"
13#include "print-tree.h"
14#include "locking.h"
15#include "volumes.h"
16#include "qgroup.h"
17
18static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
19 *root, struct btrfs_path *path, int level);
20static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
21 const struct btrfs_key *ins_key, struct btrfs_path *path,
22 int data_size, int extend);
23static int push_node_left(struct btrfs_trans_handle *trans,
24 struct extent_buffer *dst,
25 struct extent_buffer *src, int empty);
26static int balance_node_right(struct btrfs_trans_handle *trans,
27 struct extent_buffer *dst_buf,
28 struct extent_buffer *src_buf);
29static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
30 int level, int slot);
31
32static const struct btrfs_csums {
33 u16 size;
34 const char *name;
35} btrfs_csums[] = {
36 [BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
37};
38
39int btrfs_super_csum_size(const struct btrfs_super_block *s)
40{
41 u16 t = btrfs_super_csum_type(s);
42 /*
43 * csum type is validated at mount time
44 */
45 return btrfs_csums[t].size;
46}
47
48const char *btrfs_super_csum_name(u16 csum_type)
49{
50 /* csum type is validated at mount time */
51 return btrfs_csums[csum_type].name;
52}
53
54struct btrfs_path *btrfs_alloc_path(void)
55{
56 return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
57}
58
59/*
60 * set all locked nodes in the path to blocking locks. This should
61 * be done before scheduling
62 */
63noinline void btrfs_set_path_blocking(struct btrfs_path *p)
64{
65 int i;
66 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
67 if (!p->nodes[i] || !p->locks[i])
68 continue;
69 /*
70 * If we currently have a spinning reader or writer lock this
71 * will bump the count of blocking holders and drop the
72 * spinlock.
73 */
74 if (p->locks[i] == BTRFS_READ_LOCK) {
75 btrfs_set_lock_blocking_read(p->nodes[i]);
76 p->locks[i] = BTRFS_READ_LOCK_BLOCKING;
77 } else if (p->locks[i] == BTRFS_WRITE_LOCK) {
78 btrfs_set_lock_blocking_write(p->nodes[i]);
79 p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING;
80 }
81 }
82}
83
84/* this also releases the path */
85void btrfs_free_path(struct btrfs_path *p)
86{
87 if (!p)
88 return;
89 btrfs_release_path(p);
90 kmem_cache_free(btrfs_path_cachep, p);
91}
92
93/*
94 * path release drops references on the extent buffers in the path
95 * and it drops any locks held by this path
96 *
97 * It is safe to call this on paths that no locks or extent buffers held.
98 */
99noinline void btrfs_release_path(struct btrfs_path *p)
100{
101 int i;
102
103 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
104 p->slots[i] = 0;
105 if (!p->nodes[i])
106 continue;
107 if (p->locks[i]) {
108 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
109 p->locks[i] = 0;
110 }
111 free_extent_buffer(p->nodes[i]);
112 p->nodes[i] = NULL;
113 }
114}
115
116/*
117 * safely gets a reference on the root node of a tree. A lock
118 * is not taken, so a concurrent writer may put a different node
119 * at the root of the tree. See btrfs_lock_root_node for the
120 * looping required.
121 *
122 * The extent buffer returned by this has a reference taken, so
123 * it won't disappear. It may stop being the root of the tree
124 * at any time because there are no locks held.
125 */
126struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
127{
128 struct extent_buffer *eb;
129
130 while (1) {
131 rcu_read_lock();
132 eb = rcu_dereference(root->node);
133
134 /*
135 * RCU really hurts here, we could free up the root node because
136 * it was COWed but we may not get the new root node yet so do
137 * the inc_not_zero dance and if it doesn't work then
138 * synchronize_rcu and try again.
139 */
140 if (atomic_inc_not_zero(&eb->refs)) {
141 rcu_read_unlock();
142 break;
143 }
144 rcu_read_unlock();
145 synchronize_rcu();
146 }
147 return eb;
148}
149
150/* loop around taking references on and locking the root node of the
151 * tree until you end up with a lock on the root. A locked buffer
152 * is returned, with a reference held.
153 */
154struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
155{
156 struct extent_buffer *eb;
157
158 while (1) {
159 eb = btrfs_root_node(root);
160 btrfs_tree_lock(eb);
161 if (eb == root->node)
162 break;
163 btrfs_tree_unlock(eb);
164 free_extent_buffer(eb);
165 }
166 return eb;
167}
168
169/* loop around taking references on and locking the root node of the
170 * tree until you end up with a lock on the root. A locked buffer
171 * is returned, with a reference held.
172 */
173struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
174{
175 struct extent_buffer *eb;
176
177 while (1) {
178 eb = btrfs_root_node(root);
179 btrfs_tree_read_lock(eb);
180 if (eb == root->node)
181 break;
182 btrfs_tree_read_unlock(eb);
183 free_extent_buffer(eb);
184 }
185 return eb;
186}
187
188/* cowonly root (everything not a reference counted cow subvolume), just get
189 * put onto a simple dirty list. transaction.c walks this to make sure they
190 * get properly updated on disk.
191 */
192static void add_root_to_dirty_list(struct btrfs_root *root)
193{
194 struct btrfs_fs_info *fs_info = root->fs_info;
195
196 if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
197 !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
198 return;
199
200 spin_lock(&fs_info->trans_lock);
201 if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
202 /* Want the extent tree to be the last on the list */
203 if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID)
204 list_move_tail(&root->dirty_list,
205 &fs_info->dirty_cowonly_roots);
206 else
207 list_move(&root->dirty_list,
208 &fs_info->dirty_cowonly_roots);
209 }
210 spin_unlock(&fs_info->trans_lock);
211}
212
213/*
214 * used by snapshot creation to make a copy of a root for a tree with
215 * a given objectid. The buffer with the new root node is returned in
216 * cow_ret, and this func returns zero on success or a negative error code.
217 */
218int btrfs_copy_root(struct btrfs_trans_handle *trans,
219 struct btrfs_root *root,
220 struct extent_buffer *buf,
221 struct extent_buffer **cow_ret, u64 new_root_objectid)
222{
223 struct btrfs_fs_info *fs_info = root->fs_info;
224 struct extent_buffer *cow;
225 int ret = 0;
226 int level;
227 struct btrfs_disk_key disk_key;
228
229 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
230 trans->transid != fs_info->running_transaction->transid);
231 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
232 trans->transid != root->last_trans);
233
234 level = btrfs_header_level(buf);
235 if (level == 0)
236 btrfs_item_key(buf, &disk_key, 0);
237 else
238 btrfs_node_key(buf, &disk_key, 0);
239
240 cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
241 &disk_key, level, buf->start, 0);
242 if (IS_ERR(cow))
243 return PTR_ERR(cow);
244
245 copy_extent_buffer_full(cow, buf);
246 btrfs_set_header_bytenr(cow, cow->start);
247 btrfs_set_header_generation(cow, trans->transid);
248 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
249 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
250 BTRFS_HEADER_FLAG_RELOC);
251 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
252 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
253 else
254 btrfs_set_header_owner(cow, new_root_objectid);
255
256 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
257
258 WARN_ON(btrfs_header_generation(buf) > trans->transid);
259 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
260 ret = btrfs_inc_ref(trans, root, cow, 1);
261 else
262 ret = btrfs_inc_ref(trans, root, cow, 0);
263
264 if (ret)
265 return ret;
266
267 btrfs_mark_buffer_dirty(cow);
268 *cow_ret = cow;
269 return 0;
270}
271
272enum mod_log_op {
273 MOD_LOG_KEY_REPLACE,
274 MOD_LOG_KEY_ADD,
275 MOD_LOG_KEY_REMOVE,
276 MOD_LOG_KEY_REMOVE_WHILE_FREEING,
277 MOD_LOG_KEY_REMOVE_WHILE_MOVING,
278 MOD_LOG_MOVE_KEYS,
279 MOD_LOG_ROOT_REPLACE,
280};
281
282struct tree_mod_root {
283 u64 logical;
284 u8 level;
285};
286
287struct tree_mod_elem {
288 struct rb_node node;
289 u64 logical;
290 u64 seq;
291 enum mod_log_op op;
292
293 /* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
294 int slot;
295
296 /* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
297 u64 generation;
298
299 /* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
300 struct btrfs_disk_key key;
301 u64 blockptr;
302
303 /* this is used for op == MOD_LOG_MOVE_KEYS */
304 struct {
305 int dst_slot;
306 int nr_items;
307 } move;
308
309 /* this is used for op == MOD_LOG_ROOT_REPLACE */
310 struct tree_mod_root old_root;
311};
312
313/*
314 * Pull a new tree mod seq number for our operation.
315 */
316static inline u64 btrfs_inc_tree_mod_seq(struct btrfs_fs_info *fs_info)
317{
318 return atomic64_inc_return(&fs_info->tree_mod_seq);
319}
320
321/*
322 * This adds a new blocker to the tree mod log's blocker list if the @elem
323 * passed does not already have a sequence number set. So when a caller expects
324 * to record tree modifications, it should ensure to set elem->seq to zero
325 * before calling btrfs_get_tree_mod_seq.
326 * Returns a fresh, unused tree log modification sequence number, even if no new
327 * blocker was added.
328 */
329u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
330 struct seq_list *elem)
331{
332 write_lock(&fs_info->tree_mod_log_lock);
333 spin_lock(&fs_info->tree_mod_seq_lock);
334 if (!elem->seq) {
335 elem->seq = btrfs_inc_tree_mod_seq(fs_info);
336 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
337 }
338 spin_unlock(&fs_info->tree_mod_seq_lock);
339 write_unlock(&fs_info->tree_mod_log_lock);
340
341 return elem->seq;
342}
343
344void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
345 struct seq_list *elem)
346{
347 struct rb_root *tm_root;
348 struct rb_node *node;
349 struct rb_node *next;
350 struct seq_list *cur_elem;
351 struct tree_mod_elem *tm;
352 u64 min_seq = (u64)-1;
353 u64 seq_putting = elem->seq;
354
355 if (!seq_putting)
356 return;
357
358 spin_lock(&fs_info->tree_mod_seq_lock);
359 list_del(&elem->list);
360 elem->seq = 0;
361
362 list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) {
363 if (cur_elem->seq < min_seq) {
364 if (seq_putting > cur_elem->seq) {
365 /*
366 * blocker with lower sequence number exists, we
367 * cannot remove anything from the log
368 */
369 spin_unlock(&fs_info->tree_mod_seq_lock);
370 return;
371 }
372 min_seq = cur_elem->seq;
373 }
374 }
375 spin_unlock(&fs_info->tree_mod_seq_lock);
376
377 /*
378 * anything that's lower than the lowest existing (read: blocked)
379 * sequence number can be removed from the tree.
380 */
381 write_lock(&fs_info->tree_mod_log_lock);
382 tm_root = &fs_info->tree_mod_log;
383 for (node = rb_first(tm_root); node; node = next) {
384 next = rb_next(node);
385 tm = rb_entry(node, struct tree_mod_elem, node);
386 if (tm->seq > min_seq)
387 continue;
388 rb_erase(node, tm_root);
389 kfree(tm);
390 }
391 write_unlock(&fs_info->tree_mod_log_lock);
392}
393
394/*
395 * key order of the log:
396 * node/leaf start address -> sequence
397 *
398 * The 'start address' is the logical address of the *new* root node
399 * for root replace operations, or the logical address of the affected
400 * block for all other operations.
401 */
402static noinline int
403__tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
404{
405 struct rb_root *tm_root;
406 struct rb_node **new;
407 struct rb_node *parent = NULL;
408 struct tree_mod_elem *cur;
409
410 lockdep_assert_held_write(&fs_info->tree_mod_log_lock);
411
412 tm->seq = btrfs_inc_tree_mod_seq(fs_info);
413
414 tm_root = &fs_info->tree_mod_log;
415 new = &tm_root->rb_node;
416 while (*new) {
417 cur = rb_entry(*new, struct tree_mod_elem, node);
418 parent = *new;
419 if (cur->logical < tm->logical)
420 new = &((*new)->rb_left);
421 else if (cur->logical > tm->logical)
422 new = &((*new)->rb_right);
423 else if (cur->seq < tm->seq)
424 new = &((*new)->rb_left);
425 else if (cur->seq > tm->seq)
426 new = &((*new)->rb_right);
427 else
428 return -EEXIST;
429 }
430
431 rb_link_node(&tm->node, parent, new);
432 rb_insert_color(&tm->node, tm_root);
433 return 0;
434}
435
436/*
437 * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it
438 * returns zero with the tree_mod_log_lock acquired. The caller must hold
439 * this until all tree mod log insertions are recorded in the rb tree and then
440 * write unlock fs_info::tree_mod_log_lock.
441 */
442static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
443 struct extent_buffer *eb) {
444 smp_mb();
445 if (list_empty(&(fs_info)->tree_mod_seq_list))
446 return 1;
447 if (eb && btrfs_header_level(eb) == 0)
448 return 1;
449
450 write_lock(&fs_info->tree_mod_log_lock);
451 if (list_empty(&(fs_info)->tree_mod_seq_list)) {
452 write_unlock(&fs_info->tree_mod_log_lock);
453 return 1;
454 }
455
456 return 0;
457}
458
459/* Similar to tree_mod_dont_log, but doesn't acquire any locks. */
460static inline int tree_mod_need_log(const struct btrfs_fs_info *fs_info,
461 struct extent_buffer *eb)
462{
463 smp_mb();
464 if (list_empty(&(fs_info)->tree_mod_seq_list))
465 return 0;
466 if (eb && btrfs_header_level(eb) == 0)
467 return 0;
468
469 return 1;
470}
471
472static struct tree_mod_elem *
473alloc_tree_mod_elem(struct extent_buffer *eb, int slot,
474 enum mod_log_op op, gfp_t flags)
475{
476 struct tree_mod_elem *tm;
477
478 tm = kzalloc(sizeof(*tm), flags);
479 if (!tm)
480 return NULL;
481
482 tm->logical = eb->start;
483 if (op != MOD_LOG_KEY_ADD) {
484 btrfs_node_key(eb, &tm->key, slot);
485 tm->blockptr = btrfs_node_blockptr(eb, slot);
486 }
487 tm->op = op;
488 tm->slot = slot;
489 tm->generation = btrfs_node_ptr_generation(eb, slot);
490 RB_CLEAR_NODE(&tm->node);
491
492 return tm;
493}
494
495static noinline int tree_mod_log_insert_key(struct extent_buffer *eb, int slot,
496 enum mod_log_op op, gfp_t flags)
497{
498 struct tree_mod_elem *tm;
499 int ret;
500
501 if (!tree_mod_need_log(eb->fs_info, eb))
502 return 0;
503
504 tm = alloc_tree_mod_elem(eb, slot, op, flags);
505 if (!tm)
506 return -ENOMEM;
507
508 if (tree_mod_dont_log(eb->fs_info, eb)) {
509 kfree(tm);
510 return 0;
511 }
512
513 ret = __tree_mod_log_insert(eb->fs_info, tm);
514 write_unlock(&eb->fs_info->tree_mod_log_lock);
515 if (ret)
516 kfree(tm);
517
518 return ret;
519}
520
521static noinline int tree_mod_log_insert_move(struct extent_buffer *eb,
522 int dst_slot, int src_slot, int nr_items)
523{
524 struct tree_mod_elem *tm = NULL;
525 struct tree_mod_elem **tm_list = NULL;
526 int ret = 0;
527 int i;
528 int locked = 0;
529
530 if (!tree_mod_need_log(eb->fs_info, eb))
531 return 0;
532
533 tm_list = kcalloc(nr_items, sizeof(struct tree_mod_elem *), GFP_NOFS);
534 if (!tm_list)
535 return -ENOMEM;
536
537 tm = kzalloc(sizeof(*tm), GFP_NOFS);
538 if (!tm) {
539 ret = -ENOMEM;
540 goto free_tms;
541 }
542
543 tm->logical = eb->start;
544 tm->slot = src_slot;
545 tm->move.dst_slot = dst_slot;
546 tm->move.nr_items = nr_items;
547 tm->op = MOD_LOG_MOVE_KEYS;
548
549 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
550 tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot,
551 MOD_LOG_KEY_REMOVE_WHILE_MOVING, GFP_NOFS);
552 if (!tm_list[i]) {
553 ret = -ENOMEM;
554 goto free_tms;
555 }
556 }
557
558 if (tree_mod_dont_log(eb->fs_info, eb))
559 goto free_tms;
560 locked = 1;
561
562 /*
563 * When we override something during the move, we log these removals.
564 * This can only happen when we move towards the beginning of the
565 * buffer, i.e. dst_slot < src_slot.
566 */
567 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
568 ret = __tree_mod_log_insert(eb->fs_info, tm_list[i]);
569 if (ret)
570 goto free_tms;
571 }
572
573 ret = __tree_mod_log_insert(eb->fs_info, tm);
574 if (ret)
575 goto free_tms;
576 write_unlock(&eb->fs_info->tree_mod_log_lock);
577 kfree(tm_list);
578
579 return 0;
580free_tms:
581 for (i = 0; i < nr_items; i++) {
582 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
583 rb_erase(&tm_list[i]->node, &eb->fs_info->tree_mod_log);
584 kfree(tm_list[i]);
585 }
586 if (locked)
587 write_unlock(&eb->fs_info->tree_mod_log_lock);
588 kfree(tm_list);
589 kfree(tm);
590
591 return ret;
592}
593
594static inline int
595__tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
596 struct tree_mod_elem **tm_list,
597 int nritems)
598{
599 int i, j;
600 int ret;
601
602 for (i = nritems - 1; i >= 0; i--) {
603 ret = __tree_mod_log_insert(fs_info, tm_list[i]);
604 if (ret) {
605 for (j = nritems - 1; j > i; j--)
606 rb_erase(&tm_list[j]->node,
607 &fs_info->tree_mod_log);
608 return ret;
609 }
610 }
611
612 return 0;
613}
614
615static noinline int tree_mod_log_insert_root(struct extent_buffer *old_root,
616 struct extent_buffer *new_root, int log_removal)
617{
618 struct btrfs_fs_info *fs_info = old_root->fs_info;
619 struct tree_mod_elem *tm = NULL;
620 struct tree_mod_elem **tm_list = NULL;
621 int nritems = 0;
622 int ret = 0;
623 int i;
624
625 if (!tree_mod_need_log(fs_info, NULL))
626 return 0;
627
628 if (log_removal && btrfs_header_level(old_root) > 0) {
629 nritems = btrfs_header_nritems(old_root);
630 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *),
631 GFP_NOFS);
632 if (!tm_list) {
633 ret = -ENOMEM;
634 goto free_tms;
635 }
636 for (i = 0; i < nritems; i++) {
637 tm_list[i] = alloc_tree_mod_elem(old_root, i,
638 MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
639 if (!tm_list[i]) {
640 ret = -ENOMEM;
641 goto free_tms;
642 }
643 }
644 }
645
646 tm = kzalloc(sizeof(*tm), GFP_NOFS);
647 if (!tm) {
648 ret = -ENOMEM;
649 goto free_tms;
650 }
651
652 tm->logical = new_root->start;
653 tm->old_root.logical = old_root->start;
654 tm->old_root.level = btrfs_header_level(old_root);
655 tm->generation = btrfs_header_generation(old_root);
656 tm->op = MOD_LOG_ROOT_REPLACE;
657
658 if (tree_mod_dont_log(fs_info, NULL))
659 goto free_tms;
660
661 if (tm_list)
662 ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
663 if (!ret)
664 ret = __tree_mod_log_insert(fs_info, tm);
665
666 write_unlock(&fs_info->tree_mod_log_lock);
667 if (ret)
668 goto free_tms;
669 kfree(tm_list);
670
671 return ret;
672
673free_tms:
674 if (tm_list) {
675 for (i = 0; i < nritems; i++)
676 kfree(tm_list[i]);
677 kfree(tm_list);
678 }
679 kfree(tm);
680
681 return ret;
682}
683
684static struct tree_mod_elem *
685__tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
686 int smallest)
687{
688 struct rb_root *tm_root;
689 struct rb_node *node;
690 struct tree_mod_elem *cur = NULL;
691 struct tree_mod_elem *found = NULL;
692
693 read_lock(&fs_info->tree_mod_log_lock);
694 tm_root = &fs_info->tree_mod_log;
695 node = tm_root->rb_node;
696 while (node) {
697 cur = rb_entry(node, struct tree_mod_elem, node);
698 if (cur->logical < start) {
699 node = node->rb_left;
700 } else if (cur->logical > start) {
701 node = node->rb_right;
702 } else if (cur->seq < min_seq) {
703 node = node->rb_left;
704 } else if (!smallest) {
705 /* we want the node with the highest seq */
706 if (found)
707 BUG_ON(found->seq > cur->seq);
708 found = cur;
709 node = node->rb_left;
710 } else if (cur->seq > min_seq) {
711 /* we want the node with the smallest seq */
712 if (found)
713 BUG_ON(found->seq < cur->seq);
714 found = cur;
715 node = node->rb_right;
716 } else {
717 found = cur;
718 break;
719 }
720 }
721 read_unlock(&fs_info->tree_mod_log_lock);
722
723 return found;
724}
725
726/*
727 * this returns the element from the log with the smallest time sequence
728 * value that's in the log (the oldest log item). any element with a time
729 * sequence lower than min_seq will be ignored.
730 */
731static struct tree_mod_elem *
732tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
733 u64 min_seq)
734{
735 return __tree_mod_log_search(fs_info, start, min_seq, 1);
736}
737
738/*
739 * this returns the element from the log with the largest time sequence
740 * value that's in the log (the most recent log item). any element with
741 * a time sequence lower than min_seq will be ignored.
742 */
743static struct tree_mod_elem *
744tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
745{
746 return __tree_mod_log_search(fs_info, start, min_seq, 0);
747}
748
749static noinline int tree_mod_log_eb_copy(struct extent_buffer *dst,
750 struct extent_buffer *src, unsigned long dst_offset,
751 unsigned long src_offset, int nr_items)
752{
753 struct btrfs_fs_info *fs_info = dst->fs_info;
754 int ret = 0;
755 struct tree_mod_elem **tm_list = NULL;
756 struct tree_mod_elem **tm_list_add, **tm_list_rem;
757 int i;
758 int locked = 0;
759
760 if (!tree_mod_need_log(fs_info, NULL))
761 return 0;
762
763 if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
764 return 0;
765
766 tm_list = kcalloc(nr_items * 2, sizeof(struct tree_mod_elem *),
767 GFP_NOFS);
768 if (!tm_list)
769 return -ENOMEM;
770
771 tm_list_add = tm_list;
772 tm_list_rem = tm_list + nr_items;
773 for (i = 0; i < nr_items; i++) {
774 tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset,
775 MOD_LOG_KEY_REMOVE, GFP_NOFS);
776 if (!tm_list_rem[i]) {
777 ret = -ENOMEM;
778 goto free_tms;
779 }
780
781 tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset,
782 MOD_LOG_KEY_ADD, GFP_NOFS);
783 if (!tm_list_add[i]) {
784 ret = -ENOMEM;
785 goto free_tms;
786 }
787 }
788
789 if (tree_mod_dont_log(fs_info, NULL))
790 goto free_tms;
791 locked = 1;
792
793 for (i = 0; i < nr_items; i++) {
794 ret = __tree_mod_log_insert(fs_info, tm_list_rem[i]);
795 if (ret)
796 goto free_tms;
797 ret = __tree_mod_log_insert(fs_info, tm_list_add[i]);
798 if (ret)
799 goto free_tms;
800 }
801
802 write_unlock(&fs_info->tree_mod_log_lock);
803 kfree(tm_list);
804
805 return 0;
806
807free_tms:
808 for (i = 0; i < nr_items * 2; i++) {
809 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
810 rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
811 kfree(tm_list[i]);
812 }
813 if (locked)
814 write_unlock(&fs_info->tree_mod_log_lock);
815 kfree(tm_list);
816
817 return ret;
818}
819
820static noinline int tree_mod_log_free_eb(struct extent_buffer *eb)
821{
822 struct tree_mod_elem **tm_list = NULL;
823 int nritems = 0;
824 int i;
825 int ret = 0;
826
827 if (btrfs_header_level(eb) == 0)
828 return 0;
829
830 if (!tree_mod_need_log(eb->fs_info, NULL))
831 return 0;
832
833 nritems = btrfs_header_nritems(eb);
834 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *), GFP_NOFS);
835 if (!tm_list)
836 return -ENOMEM;
837
838 for (i = 0; i < nritems; i++) {
839 tm_list[i] = alloc_tree_mod_elem(eb, i,
840 MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
841 if (!tm_list[i]) {
842 ret = -ENOMEM;
843 goto free_tms;
844 }
845 }
846
847 if (tree_mod_dont_log(eb->fs_info, eb))
848 goto free_tms;
849
850 ret = __tree_mod_log_free_eb(eb->fs_info, tm_list, nritems);
851 write_unlock(&eb->fs_info->tree_mod_log_lock);
852 if (ret)
853 goto free_tms;
854 kfree(tm_list);
855
856 return 0;
857
858free_tms:
859 for (i = 0; i < nritems; i++)
860 kfree(tm_list[i]);
861 kfree(tm_list);
862
863 return ret;
864}
865
866/*
867 * check if the tree block can be shared by multiple trees
868 */
869int btrfs_block_can_be_shared(struct btrfs_root *root,
870 struct extent_buffer *buf)
871{
872 /*
873 * Tree blocks not in reference counted trees and tree roots
874 * are never shared. If a block was allocated after the last
875 * snapshot and the block was not allocated by tree relocation,
876 * we know the block is not shared.
877 */
878 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
879 buf != root->node && buf != root->commit_root &&
880 (btrfs_header_generation(buf) <=
881 btrfs_root_last_snapshot(&root->root_item) ||
882 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
883 return 1;
884
885 return 0;
886}
887
888static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
889 struct btrfs_root *root,
890 struct extent_buffer *buf,
891 struct extent_buffer *cow,
892 int *last_ref)
893{
894 struct btrfs_fs_info *fs_info = root->fs_info;
895 u64 refs;
896 u64 owner;
897 u64 flags;
898 u64 new_flags = 0;
899 int ret;
900
901 /*
902 * Backrefs update rules:
903 *
904 * Always use full backrefs for extent pointers in tree block
905 * allocated by tree relocation.
906 *
907 * If a shared tree block is no longer referenced by its owner
908 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
909 * use full backrefs for extent pointers in tree block.
910 *
911 * If a tree block is been relocating
912 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
913 * use full backrefs for extent pointers in tree block.
914 * The reason for this is some operations (such as drop tree)
915 * are only allowed for blocks use full backrefs.
916 */
917
918 if (btrfs_block_can_be_shared(root, buf)) {
919 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
920 btrfs_header_level(buf), 1,
921 &refs, &flags);
922 if (ret)
923 return ret;
924 if (refs == 0) {
925 ret = -EROFS;
926 btrfs_handle_fs_error(fs_info, ret, NULL);
927 return ret;
928 }
929 } else {
930 refs = 1;
931 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
932 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
933 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
934 else
935 flags = 0;
936 }
937
938 owner = btrfs_header_owner(buf);
939 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
940 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
941
942 if (refs > 1) {
943 if ((owner == root->root_key.objectid ||
944 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
945 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
946 ret = btrfs_inc_ref(trans, root, buf, 1);
947 if (ret)
948 return ret;
949
950 if (root->root_key.objectid ==
951 BTRFS_TREE_RELOC_OBJECTID) {
952 ret = btrfs_dec_ref(trans, root, buf, 0);
953 if (ret)
954 return ret;
955 ret = btrfs_inc_ref(trans, root, cow, 1);
956 if (ret)
957 return ret;
958 }
959 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
960 } else {
961
962 if (root->root_key.objectid ==
963 BTRFS_TREE_RELOC_OBJECTID)
964 ret = btrfs_inc_ref(trans, root, cow, 1);
965 else
966 ret = btrfs_inc_ref(trans, root, cow, 0);
967 if (ret)
968 return ret;
969 }
970 if (new_flags != 0) {
971 int level = btrfs_header_level(buf);
972
973 ret = btrfs_set_disk_extent_flags(trans,
974 buf->start,
975 buf->len,
976 new_flags, level, 0);
977 if (ret)
978 return ret;
979 }
980 } else {
981 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
982 if (root->root_key.objectid ==
983 BTRFS_TREE_RELOC_OBJECTID)
984 ret = btrfs_inc_ref(trans, root, cow, 1);
985 else
986 ret = btrfs_inc_ref(trans, root, cow, 0);
987 if (ret)
988 return ret;
989 ret = btrfs_dec_ref(trans, root, buf, 1);
990 if (ret)
991 return ret;
992 }
993 btrfs_clean_tree_block(buf);
994 *last_ref = 1;
995 }
996 return 0;
997}
998
999static struct extent_buffer *alloc_tree_block_no_bg_flush(
1000 struct btrfs_trans_handle *trans,
1001 struct btrfs_root *root,
1002 u64 parent_start,
1003 const struct btrfs_disk_key *disk_key,
1004 int level,
1005 u64 hint,
1006 u64 empty_size)
1007{
1008 struct btrfs_fs_info *fs_info = root->fs_info;
1009 struct extent_buffer *ret;
1010
1011 /*
1012 * If we are COWing a node/leaf from the extent, chunk, device or free
1013 * space trees, make sure that we do not finish block group creation of
1014 * pending block groups. We do this to avoid a deadlock.
1015 * COWing can result in allocation of a new chunk, and flushing pending
1016 * block groups (btrfs_create_pending_block_groups()) can be triggered
1017 * when finishing allocation of a new chunk. Creation of a pending block
1018 * group modifies the extent, chunk, device and free space trees,
1019 * therefore we could deadlock with ourselves since we are holding a
1020 * lock on an extent buffer that btrfs_create_pending_block_groups() may
1021 * try to COW later.
1022 * For similar reasons, we also need to delay flushing pending block
1023 * groups when splitting a leaf or node, from one of those trees, since
1024 * we are holding a write lock on it and its parent or when inserting a
1025 * new root node for one of those trees.
1026 */
1027 if (root == fs_info->extent_root ||
1028 root == fs_info->chunk_root ||
1029 root == fs_info->dev_root ||
1030 root == fs_info->free_space_root)
1031 trans->can_flush_pending_bgs = false;
1032
1033 ret = btrfs_alloc_tree_block(trans, root, parent_start,
1034 root->root_key.objectid, disk_key, level,
1035 hint, empty_size);
1036 trans->can_flush_pending_bgs = true;
1037
1038 return ret;
1039}
1040
1041/*
1042 * does the dirty work in cow of a single block. The parent block (if
1043 * supplied) is updated to point to the new cow copy. The new buffer is marked
1044 * dirty and returned locked. If you modify the block it needs to be marked
1045 * dirty again.
1046 *
1047 * search_start -- an allocation hint for the new block
1048 *
1049 * empty_size -- a hint that you plan on doing more cow. This is the size in
1050 * bytes the allocator should try to find free next to the block it returns.
1051 * This is just a hint and may be ignored by the allocator.
1052 */
1053static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
1054 struct btrfs_root *root,
1055 struct extent_buffer *buf,
1056 struct extent_buffer *parent, int parent_slot,
1057 struct extent_buffer **cow_ret,
1058 u64 search_start, u64 empty_size)
1059{
1060 struct btrfs_fs_info *fs_info = root->fs_info;
1061 struct btrfs_disk_key disk_key;
1062 struct extent_buffer *cow;
1063 int level, ret;
1064 int last_ref = 0;
1065 int unlock_orig = 0;
1066 u64 parent_start = 0;
1067
1068 if (*cow_ret == buf)
1069 unlock_orig = 1;
1070
1071 btrfs_assert_tree_locked(buf);
1072
1073 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
1074 trans->transid != fs_info->running_transaction->transid);
1075 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
1076 trans->transid != root->last_trans);
1077
1078 level = btrfs_header_level(buf);
1079
1080 if (level == 0)
1081 btrfs_item_key(buf, &disk_key, 0);
1082 else
1083 btrfs_node_key(buf, &disk_key, 0);
1084
1085 if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
1086 parent_start = parent->start;
1087
1088 cow = alloc_tree_block_no_bg_flush(trans, root, parent_start, &disk_key,
1089 level, search_start, empty_size);
1090 if (IS_ERR(cow))
1091 return PTR_ERR(cow);
1092
1093 /* cow is set to blocking by btrfs_init_new_buffer */
1094
1095 copy_extent_buffer_full(cow, buf);
1096 btrfs_set_header_bytenr(cow, cow->start);
1097 btrfs_set_header_generation(cow, trans->transid);
1098 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
1099 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
1100 BTRFS_HEADER_FLAG_RELOC);
1101 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1102 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
1103 else
1104 btrfs_set_header_owner(cow, root->root_key.objectid);
1105
1106 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
1107
1108 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
1109 if (ret) {
1110 btrfs_abort_transaction(trans, ret);
1111 return ret;
1112 }
1113
1114 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
1115 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
1116 if (ret) {
1117 btrfs_abort_transaction(trans, ret);
1118 return ret;
1119 }
1120 }
1121
1122 if (buf == root->node) {
1123 WARN_ON(parent && parent != buf);
1124 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1125 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1126 parent_start = buf->start;
1127
1128 extent_buffer_get(cow);
1129 ret = tree_mod_log_insert_root(root->node, cow, 1);
1130 BUG_ON(ret < 0);
1131 rcu_assign_pointer(root->node, cow);
1132
1133 btrfs_free_tree_block(trans, root, buf, parent_start,
1134 last_ref);
1135 free_extent_buffer(buf);
1136 add_root_to_dirty_list(root);
1137 } else {
1138 WARN_ON(trans->transid != btrfs_header_generation(parent));
1139 tree_mod_log_insert_key(parent, parent_slot,
1140 MOD_LOG_KEY_REPLACE, GFP_NOFS);
1141 btrfs_set_node_blockptr(parent, parent_slot,
1142 cow->start);
1143 btrfs_set_node_ptr_generation(parent, parent_slot,
1144 trans->transid);
1145 btrfs_mark_buffer_dirty(parent);
1146 if (last_ref) {
1147 ret = tree_mod_log_free_eb(buf);
1148 if (ret) {
1149 btrfs_abort_transaction(trans, ret);
1150 return ret;
1151 }
1152 }
1153 btrfs_free_tree_block(trans, root, buf, parent_start,
1154 last_ref);
1155 }
1156 if (unlock_orig)
1157 btrfs_tree_unlock(buf);
1158 free_extent_buffer_stale(buf);
1159 btrfs_mark_buffer_dirty(cow);
1160 *cow_ret = cow;
1161 return 0;
1162}
1163
1164/*
1165 * returns the logical address of the oldest predecessor of the given root.
1166 * entries older than time_seq are ignored.
1167 */
1168static struct tree_mod_elem *__tree_mod_log_oldest_root(
1169 struct extent_buffer *eb_root, u64 time_seq)
1170{
1171 struct tree_mod_elem *tm;
1172 struct tree_mod_elem *found = NULL;
1173 u64 root_logical = eb_root->start;
1174 int looped = 0;
1175
1176 if (!time_seq)
1177 return NULL;
1178
1179 /*
1180 * the very last operation that's logged for a root is the
1181 * replacement operation (if it is replaced at all). this has
1182 * the logical address of the *new* root, making it the very
1183 * first operation that's logged for this root.
1184 */
1185 while (1) {
1186 tm = tree_mod_log_search_oldest(eb_root->fs_info, root_logical,
1187 time_seq);
1188 if (!looped && !tm)
1189 return NULL;
1190 /*
1191 * if there are no tree operation for the oldest root, we simply
1192 * return it. this should only happen if that (old) root is at
1193 * level 0.
1194 */
1195 if (!tm)
1196 break;
1197
1198 /*
1199 * if there's an operation that's not a root replacement, we
1200 * found the oldest version of our root. normally, we'll find a
1201 * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1202 */
1203 if (tm->op != MOD_LOG_ROOT_REPLACE)
1204 break;
1205
1206 found = tm;
1207 root_logical = tm->old_root.logical;
1208 looped = 1;
1209 }
1210
1211 /* if there's no old root to return, return what we found instead */
1212 if (!found)
1213 found = tm;
1214
1215 return found;
1216}
1217
1218/*
1219 * tm is a pointer to the first operation to rewind within eb. then, all
1220 * previous operations will be rewound (until we reach something older than
1221 * time_seq).
1222 */
1223static void
1224__tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1225 u64 time_seq, struct tree_mod_elem *first_tm)
1226{
1227 u32 n;
1228 struct rb_node *next;
1229 struct tree_mod_elem *tm = first_tm;
1230 unsigned long o_dst;
1231 unsigned long o_src;
1232 unsigned long p_size = sizeof(struct btrfs_key_ptr);
1233
1234 n = btrfs_header_nritems(eb);
1235 read_lock(&fs_info->tree_mod_log_lock);
1236 while (tm && tm->seq >= time_seq) {
1237 /*
1238 * all the operations are recorded with the operator used for
1239 * the modification. as we're going backwards, we do the
1240 * opposite of each operation here.
1241 */
1242 switch (tm->op) {
1243 case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1244 BUG_ON(tm->slot < n);
1245 /* Fallthrough */
1246 case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1247 case MOD_LOG_KEY_REMOVE:
1248 btrfs_set_node_key(eb, &tm->key, tm->slot);
1249 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1250 btrfs_set_node_ptr_generation(eb, tm->slot,
1251 tm->generation);
1252 n++;
1253 break;
1254 case MOD_LOG_KEY_REPLACE:
1255 BUG_ON(tm->slot >= n);
1256 btrfs_set_node_key(eb, &tm->key, tm->slot);
1257 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1258 btrfs_set_node_ptr_generation(eb, tm->slot,
1259 tm->generation);
1260 break;
1261 case MOD_LOG_KEY_ADD:
1262 /* if a move operation is needed it's in the log */
1263 n--;
1264 break;
1265 case MOD_LOG_MOVE_KEYS:
1266 o_dst = btrfs_node_key_ptr_offset(tm->slot);
1267 o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1268 memmove_extent_buffer(eb, o_dst, o_src,
1269 tm->move.nr_items * p_size);
1270 break;
1271 case MOD_LOG_ROOT_REPLACE:
1272 /*
1273 * this operation is special. for roots, this must be
1274 * handled explicitly before rewinding.
1275 * for non-roots, this operation may exist if the node
1276 * was a root: root A -> child B; then A gets empty and
1277 * B is promoted to the new root. in the mod log, we'll
1278 * have a root-replace operation for B, a tree block
1279 * that is no root. we simply ignore that operation.
1280 */
1281 break;
1282 }
1283 next = rb_next(&tm->node);
1284 if (!next)
1285 break;
1286 tm = rb_entry(next, struct tree_mod_elem, node);
1287 if (tm->logical != first_tm->logical)
1288 break;
1289 }
1290 read_unlock(&fs_info->tree_mod_log_lock);
1291 btrfs_set_header_nritems(eb, n);
1292}
1293
1294/*
1295 * Called with eb read locked. If the buffer cannot be rewound, the same buffer
1296 * is returned. If rewind operations happen, a fresh buffer is returned. The
1297 * returned buffer is always read-locked. If the returned buffer is not the
1298 * input buffer, the lock on the input buffer is released and the input buffer
1299 * is freed (its refcount is decremented).
1300 */
1301static struct extent_buffer *
1302tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
1303 struct extent_buffer *eb, u64 time_seq)
1304{
1305 struct extent_buffer *eb_rewin;
1306 struct tree_mod_elem *tm;
1307
1308 if (!time_seq)
1309 return eb;
1310
1311 if (btrfs_header_level(eb) == 0)
1312 return eb;
1313
1314 tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1315 if (!tm)
1316 return eb;
1317
1318 btrfs_set_path_blocking(path);
1319 btrfs_set_lock_blocking_read(eb);
1320
1321 if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1322 BUG_ON(tm->slot != 0);
1323 eb_rewin = alloc_dummy_extent_buffer(fs_info, eb->start);
1324 if (!eb_rewin) {
1325 btrfs_tree_read_unlock_blocking(eb);
1326 free_extent_buffer(eb);
1327 return NULL;
1328 }
1329 btrfs_set_header_bytenr(eb_rewin, eb->start);
1330 btrfs_set_header_backref_rev(eb_rewin,
1331 btrfs_header_backref_rev(eb));
1332 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1333 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1334 } else {
1335 eb_rewin = btrfs_clone_extent_buffer(eb);
1336 if (!eb_rewin) {
1337 btrfs_tree_read_unlock_blocking(eb);
1338 free_extent_buffer(eb);
1339 return NULL;
1340 }
1341 }
1342
1343 btrfs_tree_read_unlock_blocking(eb);
1344 free_extent_buffer(eb);
1345
1346 btrfs_tree_read_lock(eb_rewin);
1347 __tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm);
1348 WARN_ON(btrfs_header_nritems(eb_rewin) >
1349 BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1350
1351 return eb_rewin;
1352}
1353
1354/*
1355 * get_old_root() rewinds the state of @root's root node to the given @time_seq
1356 * value. If there are no changes, the current root->root_node is returned. If
1357 * anything changed in between, there's a fresh buffer allocated on which the
1358 * rewind operations are done. In any case, the returned buffer is read locked.
1359 * Returns NULL on error (with no locks held).
1360 */
1361static inline struct extent_buffer *
1362get_old_root(struct btrfs_root *root, u64 time_seq)
1363{
1364 struct btrfs_fs_info *fs_info = root->fs_info;
1365 struct tree_mod_elem *tm;
1366 struct extent_buffer *eb = NULL;
1367 struct extent_buffer *eb_root;
1368 u64 eb_root_owner = 0;
1369 struct extent_buffer *old;
1370 struct tree_mod_root *old_root = NULL;
1371 u64 old_generation = 0;
1372 u64 logical;
1373 int level;
1374
1375 eb_root = btrfs_read_lock_root_node(root);
1376 tm = __tree_mod_log_oldest_root(eb_root, time_seq);
1377 if (!tm)
1378 return eb_root;
1379
1380 if (tm->op == MOD_LOG_ROOT_REPLACE) {
1381 old_root = &tm->old_root;
1382 old_generation = tm->generation;
1383 logical = old_root->logical;
1384 level = old_root->level;
1385 } else {
1386 logical = eb_root->start;
1387 level = btrfs_header_level(eb_root);
1388 }
1389
1390 tm = tree_mod_log_search(fs_info, logical, time_seq);
1391 if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1392 btrfs_tree_read_unlock(eb_root);
1393 free_extent_buffer(eb_root);
1394 old = read_tree_block(fs_info, logical, 0, level, NULL);
1395 if (WARN_ON(IS_ERR(old) || !extent_buffer_uptodate(old))) {
1396 if (!IS_ERR(old))
1397 free_extent_buffer(old);
1398 btrfs_warn(fs_info,
1399 "failed to read tree block %llu from get_old_root",
1400 logical);
1401 } else {
1402 eb = btrfs_clone_extent_buffer(old);
1403 free_extent_buffer(old);
1404 }
1405 } else if (old_root) {
1406 eb_root_owner = btrfs_header_owner(eb_root);
1407 btrfs_tree_read_unlock(eb_root);
1408 free_extent_buffer(eb_root);
1409 eb = alloc_dummy_extent_buffer(fs_info, logical);
1410 } else {
1411 btrfs_set_lock_blocking_read(eb_root);
1412 eb = btrfs_clone_extent_buffer(eb_root);
1413 btrfs_tree_read_unlock_blocking(eb_root);
1414 free_extent_buffer(eb_root);
1415 }
1416
1417 if (!eb)
1418 return NULL;
1419 btrfs_tree_read_lock(eb);
1420 if (old_root) {
1421 btrfs_set_header_bytenr(eb, eb->start);
1422 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1423 btrfs_set_header_owner(eb, eb_root_owner);
1424 btrfs_set_header_level(eb, old_root->level);
1425 btrfs_set_header_generation(eb, old_generation);
1426 }
1427 if (tm)
1428 __tree_mod_log_rewind(fs_info, eb, time_seq, tm);
1429 else
1430 WARN_ON(btrfs_header_level(eb) != 0);
1431 WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1432
1433 return eb;
1434}
1435
1436int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
1437{
1438 struct tree_mod_elem *tm;
1439 int level;
1440 struct extent_buffer *eb_root = btrfs_root_node(root);
1441
1442 tm = __tree_mod_log_oldest_root(eb_root, time_seq);
1443 if (tm && tm->op == MOD_LOG_ROOT_REPLACE) {
1444 level = tm->old_root.level;
1445 } else {
1446 level = btrfs_header_level(eb_root);
1447 }
1448 free_extent_buffer(eb_root);
1449
1450 return level;
1451}
1452
1453static inline int should_cow_block(struct btrfs_trans_handle *trans,
1454 struct btrfs_root *root,
1455 struct extent_buffer *buf)
1456{
1457 if (btrfs_is_testing(root->fs_info))
1458 return 0;
1459
1460 /* Ensure we can see the FORCE_COW bit */
1461 smp_mb__before_atomic();
1462
1463 /*
1464 * We do not need to cow a block if
1465 * 1) this block is not created or changed in this transaction;
1466 * 2) this block does not belong to TREE_RELOC tree;
1467 * 3) the root is not forced COW.
1468 *
1469 * What is forced COW:
1470 * when we create snapshot during committing the transaction,
1471 * after we've finished copying src root, we must COW the shared
1472 * block to ensure the metadata consistency.
1473 */
1474 if (btrfs_header_generation(buf) == trans->transid &&
1475 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1476 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1477 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1478 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
1479 return 0;
1480 return 1;
1481}
1482
1483/*
1484 * cows a single block, see __btrfs_cow_block for the real work.
1485 * This version of it has extra checks so that a block isn't COWed more than
1486 * once per transaction, as long as it hasn't been written yet
1487 */
1488noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1489 struct btrfs_root *root, struct extent_buffer *buf,
1490 struct extent_buffer *parent, int parent_slot,
1491 struct extent_buffer **cow_ret)
1492{
1493 struct btrfs_fs_info *fs_info = root->fs_info;
1494 u64 search_start;
1495 int ret;
1496
1497 if (test_bit(BTRFS_ROOT_DELETING, &root->state))
1498 btrfs_err(fs_info,
1499 "COW'ing blocks on a fs root that's being dropped");
1500
1501 if (trans->transaction != fs_info->running_transaction)
1502 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1503 trans->transid,
1504 fs_info->running_transaction->transid);
1505
1506 if (trans->transid != fs_info->generation)
1507 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1508 trans->transid, fs_info->generation);
1509
1510 if (!should_cow_block(trans, root, buf)) {
1511 trans->dirty = true;
1512 *cow_ret = buf;
1513 return 0;
1514 }
1515
1516 search_start = buf->start & ~((u64)SZ_1G - 1);
1517
1518 if (parent)
1519 btrfs_set_lock_blocking_write(parent);
1520 btrfs_set_lock_blocking_write(buf);
1521
1522 /*
1523 * Before CoWing this block for later modification, check if it's
1524 * the subtree root and do the delayed subtree trace if needed.
1525 *
1526 * Also We don't care about the error, as it's handled internally.
1527 */
1528 btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
1529 ret = __btrfs_cow_block(trans, root, buf, parent,
1530 parent_slot, cow_ret, search_start, 0);
1531
1532 trace_btrfs_cow_block(root, buf, *cow_ret);
1533
1534 return ret;
1535}
1536
1537/*
1538 * helper function for defrag to decide if two blocks pointed to by a
1539 * node are actually close by
1540 */
1541static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1542{
1543 if (blocknr < other && other - (blocknr + blocksize) < 32768)
1544 return 1;
1545 if (blocknr > other && blocknr - (other + blocksize) < 32768)
1546 return 1;
1547 return 0;
1548}
1549
1550/*
1551 * compare two keys in a memcmp fashion
1552 */
1553static int comp_keys(const struct btrfs_disk_key *disk,
1554 const struct btrfs_key *k2)
1555{
1556 struct btrfs_key k1;
1557
1558 btrfs_disk_key_to_cpu(&k1, disk);
1559
1560 return btrfs_comp_cpu_keys(&k1, k2);
1561}
1562
1563/*
1564 * same as comp_keys only with two btrfs_key's
1565 */
1566int btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
1567{
1568 if (k1->objectid > k2->objectid)
1569 return 1;
1570 if (k1->objectid < k2->objectid)
1571 return -1;
1572 if (k1->type > k2->type)
1573 return 1;
1574 if (k1->type < k2->type)
1575 return -1;
1576 if (k1->offset > k2->offset)
1577 return 1;
1578 if (k1->offset < k2->offset)
1579 return -1;
1580 return 0;
1581}
1582
1583/*
1584 * this is used by the defrag code to go through all the
1585 * leaves pointed to by a node and reallocate them so that
1586 * disk order is close to key order
1587 */
1588int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1589 struct btrfs_root *root, struct extent_buffer *parent,
1590 int start_slot, u64 *last_ret,
1591 struct btrfs_key *progress)
1592{
1593 struct btrfs_fs_info *fs_info = root->fs_info;
1594 struct extent_buffer *cur;
1595 u64 blocknr;
1596 u64 gen;
1597 u64 search_start = *last_ret;
1598 u64 last_block = 0;
1599 u64 other;
1600 u32 parent_nritems;
1601 int end_slot;
1602 int i;
1603 int err = 0;
1604 int parent_level;
1605 int uptodate;
1606 u32 blocksize;
1607 int progress_passed = 0;
1608 struct btrfs_disk_key disk_key;
1609
1610 parent_level = btrfs_header_level(parent);
1611
1612 WARN_ON(trans->transaction != fs_info->running_transaction);
1613 WARN_ON(trans->transid != fs_info->generation);
1614
1615 parent_nritems = btrfs_header_nritems(parent);
1616 blocksize = fs_info->nodesize;
1617 end_slot = parent_nritems - 1;
1618
1619 if (parent_nritems <= 1)
1620 return 0;
1621
1622 btrfs_set_lock_blocking_write(parent);
1623
1624 for (i = start_slot; i <= end_slot; i++) {
1625 struct btrfs_key first_key;
1626 int close = 1;
1627
1628 btrfs_node_key(parent, &disk_key, i);
1629 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1630 continue;
1631
1632 progress_passed = 1;
1633 blocknr = btrfs_node_blockptr(parent, i);
1634 gen = btrfs_node_ptr_generation(parent, i);
1635 btrfs_node_key_to_cpu(parent, &first_key, i);
1636 if (last_block == 0)
1637 last_block = blocknr;
1638
1639 if (i > 0) {
1640 other = btrfs_node_blockptr(parent, i - 1);
1641 close = close_blocks(blocknr, other, blocksize);
1642 }
1643 if (!close && i < end_slot) {
1644 other = btrfs_node_blockptr(parent, i + 1);
1645 close = close_blocks(blocknr, other, blocksize);
1646 }
1647 if (close) {
1648 last_block = blocknr;
1649 continue;
1650 }
1651
1652 cur = find_extent_buffer(fs_info, blocknr);
1653 if (cur)
1654 uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1655 else
1656 uptodate = 0;
1657 if (!cur || !uptodate) {
1658 if (!cur) {
1659 cur = read_tree_block(fs_info, blocknr, gen,
1660 parent_level - 1,
1661 &first_key);
1662 if (IS_ERR(cur)) {
1663 return PTR_ERR(cur);
1664 } else if (!extent_buffer_uptodate(cur)) {
1665 free_extent_buffer(cur);
1666 return -EIO;
1667 }
1668 } else if (!uptodate) {
1669 err = btrfs_read_buffer(cur, gen,
1670 parent_level - 1,&first_key);
1671 if (err) {
1672 free_extent_buffer(cur);
1673 return err;
1674 }
1675 }
1676 }
1677 if (search_start == 0)
1678 search_start = last_block;
1679
1680 btrfs_tree_lock(cur);
1681 btrfs_set_lock_blocking_write(cur);
1682 err = __btrfs_cow_block(trans, root, cur, parent, i,
1683 &cur, search_start,
1684 min(16 * blocksize,
1685 (end_slot - i) * blocksize));
1686 if (err) {
1687 btrfs_tree_unlock(cur);
1688 free_extent_buffer(cur);
1689 break;
1690 }
1691 search_start = cur->start;
1692 last_block = cur->start;
1693 *last_ret = search_start;
1694 btrfs_tree_unlock(cur);
1695 free_extent_buffer(cur);
1696 }
1697 return err;
1698}
1699
1700/*
1701 * search for key in the extent_buffer. The items start at offset p,
1702 * and they are item_size apart. There are 'max' items in p.
1703 *
1704 * the slot in the array is returned via slot, and it points to
1705 * the place where you would insert key if it is not found in
1706 * the array.
1707 *
1708 * slot may point to max if the key is bigger than all of the keys
1709 */
1710static noinline int generic_bin_search(struct extent_buffer *eb,
1711 unsigned long p, int item_size,
1712 const struct btrfs_key *key,
1713 int max, int *slot)
1714{
1715 int low = 0;
1716 int high = max;
1717 int mid;
1718 int ret;
1719 struct btrfs_disk_key *tmp = NULL;
1720 struct btrfs_disk_key unaligned;
1721 unsigned long offset;
1722 char *kaddr = NULL;
1723 unsigned long map_start = 0;
1724 unsigned long map_len = 0;
1725 int err;
1726
1727 if (low > high) {
1728 btrfs_err(eb->fs_info,
1729 "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
1730 __func__, low, high, eb->start,
1731 btrfs_header_owner(eb), btrfs_header_level(eb));
1732 return -EINVAL;
1733 }
1734
1735 while (low < high) {
1736 mid = (low + high) / 2;
1737 offset = p + mid * item_size;
1738
1739 if (!kaddr || offset < map_start ||
1740 (offset + sizeof(struct btrfs_disk_key)) >
1741 map_start + map_len) {
1742
1743 err = map_private_extent_buffer(eb, offset,
1744 sizeof(struct btrfs_disk_key),
1745 &kaddr, &map_start, &map_len);
1746
1747 if (!err) {
1748 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1749 map_start);
1750 } else if (err == 1) {
1751 read_extent_buffer(eb, &unaligned,
1752 offset, sizeof(unaligned));
1753 tmp = &unaligned;
1754 } else {
1755 return err;
1756 }
1757
1758 } else {
1759 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1760 map_start);
1761 }
1762 ret = comp_keys(tmp, key);
1763
1764 if (ret < 0)
1765 low = mid + 1;
1766 else if (ret > 0)
1767 high = mid;
1768 else {
1769 *slot = mid;
1770 return 0;
1771 }
1772 }
1773 *slot = low;
1774 return 1;
1775}
1776
1777/*
1778 * simple bin_search frontend that does the right thing for
1779 * leaves vs nodes
1780 */
1781int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
1782 int level, int *slot)
1783{
1784 if (level == 0)
1785 return generic_bin_search(eb,
1786 offsetof(struct btrfs_leaf, items),
1787 sizeof(struct btrfs_item),
1788 key, btrfs_header_nritems(eb),
1789 slot);
1790 else
1791 return generic_bin_search(eb,
1792 offsetof(struct btrfs_node, ptrs),
1793 sizeof(struct btrfs_key_ptr),
1794 key, btrfs_header_nritems(eb),
1795 slot);
1796}
1797
1798static void root_add_used(struct btrfs_root *root, u32 size)
1799{
1800 spin_lock(&root->accounting_lock);
1801 btrfs_set_root_used(&root->root_item,
1802 btrfs_root_used(&root->root_item) + size);
1803 spin_unlock(&root->accounting_lock);
1804}
1805
1806static void root_sub_used(struct btrfs_root *root, u32 size)
1807{
1808 spin_lock(&root->accounting_lock);
1809 btrfs_set_root_used(&root->root_item,
1810 btrfs_root_used(&root->root_item) - size);
1811 spin_unlock(&root->accounting_lock);
1812}
1813
1814/* given a node and slot number, this reads the blocks it points to. The
1815 * extent buffer is returned with a reference taken (but unlocked).
1816 */
1817struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
1818 int slot)
1819{
1820 int level = btrfs_header_level(parent);
1821 struct extent_buffer *eb;
1822 struct btrfs_key first_key;
1823
1824 if (slot < 0 || slot >= btrfs_header_nritems(parent))
1825 return ERR_PTR(-ENOENT);
1826
1827 BUG_ON(level == 0);
1828
1829 btrfs_node_key_to_cpu(parent, &first_key, slot);
1830 eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
1831 btrfs_node_ptr_generation(parent, slot),
1832 level - 1, &first_key);
1833 if (!IS_ERR(eb) && !extent_buffer_uptodate(eb)) {
1834 free_extent_buffer(eb);
1835 eb = ERR_PTR(-EIO);
1836 }
1837
1838 return eb;
1839}
1840
1841/*
1842 * node level balancing, used to make sure nodes are in proper order for
1843 * item deletion. We balance from the top down, so we have to make sure
1844 * that a deletion won't leave an node completely empty later on.
1845 */
1846static noinline int balance_level(struct btrfs_trans_handle *trans,
1847 struct btrfs_root *root,
1848 struct btrfs_path *path, int level)
1849{
1850 struct btrfs_fs_info *fs_info = root->fs_info;
1851 struct extent_buffer *right = NULL;
1852 struct extent_buffer *mid;
1853 struct extent_buffer *left = NULL;
1854 struct extent_buffer *parent = NULL;
1855 int ret = 0;
1856 int wret;
1857 int pslot;
1858 int orig_slot = path->slots[level];
1859 u64 orig_ptr;
1860
1861 ASSERT(level > 0);
1862
1863 mid = path->nodes[level];
1864
1865 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1866 path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1867 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1868
1869 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1870
1871 if (level < BTRFS_MAX_LEVEL - 1) {
1872 parent = path->nodes[level + 1];
1873 pslot = path->slots[level + 1];
1874 }
1875
1876 /*
1877 * deal with the case where there is only one pointer in the root
1878 * by promoting the node below to a root
1879 */
1880 if (!parent) {
1881 struct extent_buffer *child;
1882
1883 if (btrfs_header_nritems(mid) != 1)
1884 return 0;
1885
1886 /* promote the child to a root */
1887 child = btrfs_read_node_slot(mid, 0);
1888 if (IS_ERR(child)) {
1889 ret = PTR_ERR(child);
1890 btrfs_handle_fs_error(fs_info, ret, NULL);
1891 goto enospc;
1892 }
1893
1894 btrfs_tree_lock(child);
1895 btrfs_set_lock_blocking_write(child);
1896 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1897 if (ret) {
1898 btrfs_tree_unlock(child);
1899 free_extent_buffer(child);
1900 goto enospc;
1901 }
1902
1903 ret = tree_mod_log_insert_root(root->node, child, 1);
1904 BUG_ON(ret < 0);
1905 rcu_assign_pointer(root->node, child);
1906
1907 add_root_to_dirty_list(root);
1908 btrfs_tree_unlock(child);
1909
1910 path->locks[level] = 0;
1911 path->nodes[level] = NULL;
1912 btrfs_clean_tree_block(mid);
1913 btrfs_tree_unlock(mid);
1914 /* once for the path */
1915 free_extent_buffer(mid);
1916
1917 root_sub_used(root, mid->len);
1918 btrfs_free_tree_block(trans, root, mid, 0, 1);
1919 /* once for the root ptr */
1920 free_extent_buffer_stale(mid);
1921 return 0;
1922 }
1923 if (btrfs_header_nritems(mid) >
1924 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
1925 return 0;
1926
1927 left = btrfs_read_node_slot(parent, pslot - 1);
1928 if (IS_ERR(left))
1929 left = NULL;
1930
1931 if (left) {
1932 btrfs_tree_lock(left);
1933 btrfs_set_lock_blocking_write(left);
1934 wret = btrfs_cow_block(trans, root, left,
1935 parent, pslot - 1, &left);
1936 if (wret) {
1937 ret = wret;
1938 goto enospc;
1939 }
1940 }
1941
1942 right = btrfs_read_node_slot(parent, pslot + 1);
1943 if (IS_ERR(right))
1944 right = NULL;
1945
1946 if (right) {
1947 btrfs_tree_lock(right);
1948 btrfs_set_lock_blocking_write(right);
1949 wret = btrfs_cow_block(trans, root, right,
1950 parent, pslot + 1, &right);
1951 if (wret) {
1952 ret = wret;
1953 goto enospc;
1954 }
1955 }
1956
1957 /* first, try to make some room in the middle buffer */
1958 if (left) {
1959 orig_slot += btrfs_header_nritems(left);
1960 wret = push_node_left(trans, left, mid, 1);
1961 if (wret < 0)
1962 ret = wret;
1963 }
1964
1965 /*
1966 * then try to empty the right most buffer into the middle
1967 */
1968 if (right) {
1969 wret = push_node_left(trans, mid, right, 1);
1970 if (wret < 0 && wret != -ENOSPC)
1971 ret = wret;
1972 if (btrfs_header_nritems(right) == 0) {
1973 btrfs_clean_tree_block(right);
1974 btrfs_tree_unlock(right);
1975 del_ptr(root, path, level + 1, pslot + 1);
1976 root_sub_used(root, right->len);
1977 btrfs_free_tree_block(trans, root, right, 0, 1);
1978 free_extent_buffer_stale(right);
1979 right = NULL;
1980 } else {
1981 struct btrfs_disk_key right_key;
1982 btrfs_node_key(right, &right_key, 0);
1983 ret = tree_mod_log_insert_key(parent, pslot + 1,
1984 MOD_LOG_KEY_REPLACE, GFP_NOFS);
1985 BUG_ON(ret < 0);
1986 btrfs_set_node_key(parent, &right_key, pslot + 1);
1987 btrfs_mark_buffer_dirty(parent);
1988 }
1989 }
1990 if (btrfs_header_nritems(mid) == 1) {
1991 /*
1992 * we're not allowed to leave a node with one item in the
1993 * tree during a delete. A deletion from lower in the tree
1994 * could try to delete the only pointer in this node.
1995 * So, pull some keys from the left.
1996 * There has to be a left pointer at this point because
1997 * otherwise we would have pulled some pointers from the
1998 * right
1999 */
2000 if (!left) {
2001 ret = -EROFS;
2002 btrfs_handle_fs_error(fs_info, ret, NULL);
2003 goto enospc;
2004 }
2005 wret = balance_node_right(trans, mid, left);
2006 if (wret < 0) {
2007 ret = wret;
2008 goto enospc;
2009 }
2010 if (wret == 1) {
2011 wret = push_node_left(trans, left, mid, 1);
2012 if (wret < 0)
2013 ret = wret;
2014 }
2015 BUG_ON(wret == 1);
2016 }
2017 if (btrfs_header_nritems(mid) == 0) {
2018 btrfs_clean_tree_block(mid);
2019 btrfs_tree_unlock(mid);
2020 del_ptr(root, path, level + 1, pslot);
2021 root_sub_used(root, mid->len);
2022 btrfs_free_tree_block(trans, root, mid, 0, 1);
2023 free_extent_buffer_stale(mid);
2024 mid = NULL;
2025 } else {
2026 /* update the parent key to reflect our changes */
2027 struct btrfs_disk_key mid_key;
2028 btrfs_node_key(mid, &mid_key, 0);
2029 ret = tree_mod_log_insert_key(parent, pslot,
2030 MOD_LOG_KEY_REPLACE, GFP_NOFS);
2031 BUG_ON(ret < 0);
2032 btrfs_set_node_key(parent, &mid_key, pslot);
2033 btrfs_mark_buffer_dirty(parent);
2034 }
2035
2036 /* update the path */
2037 if (left) {
2038 if (btrfs_header_nritems(left) > orig_slot) {
2039 extent_buffer_get(left);
2040 /* left was locked after cow */
2041 path->nodes[level] = left;
2042 path->slots[level + 1] -= 1;
2043 path->slots[level] = orig_slot;
2044 if (mid) {
2045 btrfs_tree_unlock(mid);
2046 free_extent_buffer(mid);
2047 }
2048 } else {
2049 orig_slot -= btrfs_header_nritems(left);
2050 path->slots[level] = orig_slot;
2051 }
2052 }
2053 /* double check we haven't messed things up */
2054 if (orig_ptr !=
2055 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
2056 BUG();
2057enospc:
2058 if (right) {
2059 btrfs_tree_unlock(right);
2060 free_extent_buffer(right);
2061 }
2062 if (left) {
2063 if (path->nodes[level] != left)
2064 btrfs_tree_unlock(left);
2065 free_extent_buffer(left);
2066 }
2067 return ret;
2068}
2069
2070/* Node balancing for insertion. Here we only split or push nodes around
2071 * when they are completely full. This is also done top down, so we
2072 * have to be pessimistic.
2073 */
2074static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
2075 struct btrfs_root *root,
2076 struct btrfs_path *path, int level)
2077{
2078 struct btrfs_fs_info *fs_info = root->fs_info;
2079 struct extent_buffer *right = NULL;
2080 struct extent_buffer *mid;
2081 struct extent_buffer *left = NULL;
2082 struct extent_buffer *parent = NULL;
2083 int ret = 0;
2084 int wret;
2085 int pslot;
2086 int orig_slot = path->slots[level];
2087
2088 if (level == 0)
2089 return 1;
2090
2091 mid = path->nodes[level];
2092 WARN_ON(btrfs_header_generation(mid) != trans->transid);
2093
2094 if (level < BTRFS_MAX_LEVEL - 1) {
2095 parent = path->nodes[level + 1];
2096 pslot = path->slots[level + 1];
2097 }
2098
2099 if (!parent)
2100 return 1;
2101
2102 left = btrfs_read_node_slot(parent, pslot - 1);
2103 if (IS_ERR(left))
2104 left = NULL;
2105
2106 /* first, try to make some room in the middle buffer */
2107 if (left) {
2108 u32 left_nr;
2109
2110 btrfs_tree_lock(left);
2111 btrfs_set_lock_blocking_write(left);
2112
2113 left_nr = btrfs_header_nritems(left);
2114 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2115 wret = 1;
2116 } else {
2117 ret = btrfs_cow_block(trans, root, left, parent,
2118 pslot - 1, &left);
2119 if (ret)
2120 wret = 1;
2121 else {
2122 wret = push_node_left(trans, left, mid, 0);
2123 }
2124 }
2125 if (wret < 0)
2126 ret = wret;
2127 if (wret == 0) {
2128 struct btrfs_disk_key disk_key;
2129 orig_slot += left_nr;
2130 btrfs_node_key(mid, &disk_key, 0);
2131 ret = tree_mod_log_insert_key(parent, pslot,
2132 MOD_LOG_KEY_REPLACE, GFP_NOFS);
2133 BUG_ON(ret < 0);
2134 btrfs_set_node_key(parent, &disk_key, pslot);
2135 btrfs_mark_buffer_dirty(parent);
2136 if (btrfs_header_nritems(left) > orig_slot) {
2137 path->nodes[level] = left;
2138 path->slots[level + 1] -= 1;
2139 path->slots[level] = orig_slot;
2140 btrfs_tree_unlock(mid);
2141 free_extent_buffer(mid);
2142 } else {
2143 orig_slot -=
2144 btrfs_header_nritems(left);
2145 path->slots[level] = orig_slot;
2146 btrfs_tree_unlock(left);
2147 free_extent_buffer(left);
2148 }
2149 return 0;
2150 }
2151 btrfs_tree_unlock(left);
2152 free_extent_buffer(left);
2153 }
2154 right = btrfs_read_node_slot(parent, pslot + 1);
2155 if (IS_ERR(right))
2156 right = NULL;
2157
2158 /*
2159 * then try to empty the right most buffer into the middle
2160 */
2161 if (right) {
2162 u32 right_nr;
2163
2164 btrfs_tree_lock(right);
2165 btrfs_set_lock_blocking_write(right);
2166
2167 right_nr = btrfs_header_nritems(right);
2168 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2169 wret = 1;
2170 } else {
2171 ret = btrfs_cow_block(trans, root, right,
2172 parent, pslot + 1,
2173 &right);
2174 if (ret)
2175 wret = 1;
2176 else {
2177 wret = balance_node_right(trans, right, mid);
2178 }
2179 }
2180 if (wret < 0)
2181 ret = wret;
2182 if (wret == 0) {
2183 struct btrfs_disk_key disk_key;
2184
2185 btrfs_node_key(right, &disk_key, 0);
2186 ret = tree_mod_log_insert_key(parent, pslot + 1,
2187 MOD_LOG_KEY_REPLACE, GFP_NOFS);
2188 BUG_ON(ret < 0);
2189 btrfs_set_node_key(parent, &disk_key, pslot + 1);
2190 btrfs_mark_buffer_dirty(parent);
2191
2192 if (btrfs_header_nritems(mid) <= orig_slot) {
2193 path->nodes[level] = right;
2194 path->slots[level + 1] += 1;
2195 path->slots[level] = orig_slot -
2196 btrfs_header_nritems(mid);
2197 btrfs_tree_unlock(mid);
2198 free_extent_buffer(mid);
2199 } else {
2200 btrfs_tree_unlock(right);
2201 free_extent_buffer(right);
2202 }
2203 return 0;
2204 }
2205 btrfs_tree_unlock(right);
2206 free_extent_buffer(right);
2207 }
2208 return 1;
2209}
2210
2211/*
2212 * readahead one full node of leaves, finding things that are close
2213 * to the block in 'slot', and triggering ra on them.
2214 */
2215static void reada_for_search(struct btrfs_fs_info *fs_info,
2216 struct btrfs_path *path,
2217 int level, int slot, u64 objectid)
2218{
2219 struct extent_buffer *node;
2220 struct btrfs_disk_key disk_key;
2221 u32 nritems;
2222 u64 search;
2223 u64 target;
2224 u64 nread = 0;
2225 struct extent_buffer *eb;
2226 u32 nr;
2227 u32 blocksize;
2228 u32 nscan = 0;
2229
2230 if (level != 1)
2231 return;
2232
2233 if (!path->nodes[level])
2234 return;
2235
2236 node = path->nodes[level];
2237
2238 search = btrfs_node_blockptr(node, slot);
2239 blocksize = fs_info->nodesize;
2240 eb = find_extent_buffer(fs_info, search);
2241 if (eb) {
2242 free_extent_buffer(eb);
2243 return;
2244 }
2245
2246 target = search;
2247
2248 nritems = btrfs_header_nritems(node);
2249 nr = slot;
2250
2251 while (1) {
2252 if (path->reada == READA_BACK) {
2253 if (nr == 0)
2254 break;
2255 nr--;
2256 } else if (path->reada == READA_FORWARD) {
2257 nr++;
2258 if (nr >= nritems)
2259 break;
2260 }
2261 if (path->reada == READA_BACK && objectid) {
2262 btrfs_node_key(node, &disk_key, nr);
2263 if (btrfs_disk_key_objectid(&disk_key) != objectid)
2264 break;
2265 }
2266 search = btrfs_node_blockptr(node, nr);
2267 if ((search <= target && target - search <= 65536) ||
2268 (search > target && search - target <= 65536)) {
2269 readahead_tree_block(fs_info, search);
2270 nread += blocksize;
2271 }
2272 nscan++;
2273 if ((nread > 65536 || nscan > 32))
2274 break;
2275 }
2276}
2277
2278static noinline void reada_for_balance(struct btrfs_fs_info *fs_info,
2279 struct btrfs_path *path, int level)
2280{
2281 int slot;
2282 int nritems;
2283 struct extent_buffer *parent;
2284 struct extent_buffer *eb;
2285 u64 gen;
2286 u64 block1 = 0;
2287 u64 block2 = 0;
2288
2289 parent = path->nodes[level + 1];
2290 if (!parent)
2291 return;
2292
2293 nritems = btrfs_header_nritems(parent);
2294 slot = path->slots[level + 1];
2295
2296 if (slot > 0) {
2297 block1 = btrfs_node_blockptr(parent, slot - 1);
2298 gen = btrfs_node_ptr_generation(parent, slot - 1);
2299 eb = find_extent_buffer(fs_info, block1);
2300 /*
2301 * if we get -eagain from btrfs_buffer_uptodate, we
2302 * don't want to return eagain here. That will loop
2303 * forever
2304 */
2305 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2306 block1 = 0;
2307 free_extent_buffer(eb);
2308 }
2309 if (slot + 1 < nritems) {
2310 block2 = btrfs_node_blockptr(parent, slot + 1);
2311 gen = btrfs_node_ptr_generation(parent, slot + 1);
2312 eb = find_extent_buffer(fs_info, block2);
2313 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2314 block2 = 0;
2315 free_extent_buffer(eb);
2316 }
2317
2318 if (block1)
2319 readahead_tree_block(fs_info, block1);
2320 if (block2)
2321 readahead_tree_block(fs_info, block2);
2322}
2323
2324
2325/*
2326 * when we walk down the tree, it is usually safe to unlock the higher layers
2327 * in the tree. The exceptions are when our path goes through slot 0, because
2328 * operations on the tree might require changing key pointers higher up in the
2329 * tree.
2330 *
2331 * callers might also have set path->keep_locks, which tells this code to keep
2332 * the lock if the path points to the last slot in the block. This is part of
2333 * walking through the tree, and selecting the next slot in the higher block.
2334 *
2335 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
2336 * if lowest_unlock is 1, level 0 won't be unlocked
2337 */
2338static noinline void unlock_up(struct btrfs_path *path, int level,
2339 int lowest_unlock, int min_write_lock_level,
2340 int *write_lock_level)
2341{
2342 int i;
2343 int skip_level = level;
2344 int no_skips = 0;
2345 struct extent_buffer *t;
2346
2347 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2348 if (!path->nodes[i])
2349 break;
2350 if (!path->locks[i])
2351 break;
2352 if (!no_skips && path->slots[i] == 0) {
2353 skip_level = i + 1;
2354 continue;
2355 }
2356 if (!no_skips && path->keep_locks) {
2357 u32 nritems;
2358 t = path->nodes[i];
2359 nritems = btrfs_header_nritems(t);
2360 if (nritems < 1 || path->slots[i] >= nritems - 1) {
2361 skip_level = i + 1;
2362 continue;
2363 }
2364 }
2365 if (skip_level < i && i >= lowest_unlock)
2366 no_skips = 1;
2367
2368 t = path->nodes[i];
2369 if (i >= lowest_unlock && i > skip_level) {
2370 btrfs_tree_unlock_rw(t, path->locks[i]);
2371 path->locks[i] = 0;
2372 if (write_lock_level &&
2373 i > min_write_lock_level &&
2374 i <= *write_lock_level) {
2375 *write_lock_level = i - 1;
2376 }
2377 }
2378 }
2379}
2380
2381/*
2382 * This releases any locks held in the path starting at level and
2383 * going all the way up to the root.
2384 *
2385 * btrfs_search_slot will keep the lock held on higher nodes in a few
2386 * corner cases, such as COW of the block at slot zero in the node. This
2387 * ignores those rules, and it should only be called when there are no
2388 * more updates to be done higher up in the tree.
2389 */
2390noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
2391{
2392 int i;
2393
2394 if (path->keep_locks)
2395 return;
2396
2397 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2398 if (!path->nodes[i])
2399 continue;
2400 if (!path->locks[i])
2401 continue;
2402 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
2403 path->locks[i] = 0;
2404 }
2405}
2406
2407/*
2408 * helper function for btrfs_search_slot. The goal is to find a block
2409 * in cache without setting the path to blocking. If we find the block
2410 * we return zero and the path is unchanged.
2411 *
2412 * If we can't find the block, we set the path blocking and do some
2413 * reada. -EAGAIN is returned and the search must be repeated.
2414 */
2415static int
2416read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
2417 struct extent_buffer **eb_ret, int level, int slot,
2418 const struct btrfs_key *key)
2419{
2420 struct btrfs_fs_info *fs_info = root->fs_info;
2421 u64 blocknr;
2422 u64 gen;
2423 struct extent_buffer *b = *eb_ret;
2424 struct extent_buffer *tmp;
2425 struct btrfs_key first_key;
2426 int ret;
2427 int parent_level;
2428
2429 blocknr = btrfs_node_blockptr(b, slot);
2430 gen = btrfs_node_ptr_generation(b, slot);
2431 parent_level = btrfs_header_level(b);
2432 btrfs_node_key_to_cpu(b, &first_key, slot);
2433
2434 tmp = find_extent_buffer(fs_info, blocknr);
2435 if (tmp) {
2436 /* first we do an atomic uptodate check */
2437 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2438 /*
2439 * Do extra check for first_key, eb can be stale due to
2440 * being cached, read from scrub, or have multiple
2441 * parents (shared tree blocks).
2442 */
2443 if (btrfs_verify_level_key(tmp,
2444 parent_level - 1, &first_key, gen)) {
2445 free_extent_buffer(tmp);
2446 return -EUCLEAN;
2447 }
2448 *eb_ret = tmp;
2449 return 0;
2450 }
2451
2452 /* the pages were up to date, but we failed
2453 * the generation number check. Do a full
2454 * read for the generation number that is correct.
2455 * We must do this without dropping locks so
2456 * we can trust our generation number
2457 */
2458 btrfs_set_path_blocking(p);
2459
2460 /* now we're allowed to do a blocking uptodate check */
2461 ret = btrfs_read_buffer(tmp, gen, parent_level - 1, &first_key);
2462 if (!ret) {
2463 *eb_ret = tmp;
2464 return 0;
2465 }
2466 free_extent_buffer(tmp);
2467 btrfs_release_path(p);
2468 return -EIO;
2469 }
2470
2471 /*
2472 * reduce lock contention at high levels
2473 * of the btree by dropping locks before
2474 * we read. Don't release the lock on the current
2475 * level because we need to walk this node to figure
2476 * out which blocks to read.
2477 */
2478 btrfs_unlock_up_safe(p, level + 1);
2479 btrfs_set_path_blocking(p);
2480
2481 if (p->reada != READA_NONE)
2482 reada_for_search(fs_info, p, level, slot, key->objectid);
2483
2484 ret = -EAGAIN;
2485 tmp = read_tree_block(fs_info, blocknr, gen, parent_level - 1,
2486 &first_key);
2487 if (!IS_ERR(tmp)) {
2488 /*
2489 * If the read above didn't mark this buffer up to date,
2490 * it will never end up being up to date. Set ret to EIO now
2491 * and give up so that our caller doesn't loop forever
2492 * on our EAGAINs.
2493 */
2494 if (!extent_buffer_uptodate(tmp))
2495 ret = -EIO;
2496 free_extent_buffer(tmp);
2497 } else {
2498 ret = PTR_ERR(tmp);
2499 }
2500
2501 btrfs_release_path(p);
2502 return ret;
2503}
2504
2505/*
2506 * helper function for btrfs_search_slot. This does all of the checks
2507 * for node-level blocks and does any balancing required based on
2508 * the ins_len.
2509 *
2510 * If no extra work was required, zero is returned. If we had to
2511 * drop the path, -EAGAIN is returned and btrfs_search_slot must
2512 * start over
2513 */
2514static int
2515setup_nodes_for_search(struct btrfs_trans_handle *trans,
2516 struct btrfs_root *root, struct btrfs_path *p,
2517 struct extent_buffer *b, int level, int ins_len,
2518 int *write_lock_level)
2519{
2520 struct btrfs_fs_info *fs_info = root->fs_info;
2521 int ret;
2522
2523 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2524 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
2525 int sret;
2526
2527 if (*write_lock_level < level + 1) {
2528 *write_lock_level = level + 1;
2529 btrfs_release_path(p);
2530 goto again;
2531 }
2532
2533 btrfs_set_path_blocking(p);
2534 reada_for_balance(fs_info, p, level);
2535 sret = split_node(trans, root, p, level);
2536
2537 BUG_ON(sret > 0);
2538 if (sret) {
2539 ret = sret;
2540 goto done;
2541 }
2542 b = p->nodes[level];
2543 } else if (ins_len < 0 && btrfs_header_nritems(b) <
2544 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
2545 int sret;
2546
2547 if (*write_lock_level < level + 1) {
2548 *write_lock_level = level + 1;
2549 btrfs_release_path(p);
2550 goto again;
2551 }
2552
2553 btrfs_set_path_blocking(p);
2554 reada_for_balance(fs_info, p, level);
2555 sret = balance_level(trans, root, p, level);
2556
2557 if (sret) {
2558 ret = sret;
2559 goto done;
2560 }
2561 b = p->nodes[level];
2562 if (!b) {
2563 btrfs_release_path(p);
2564 goto again;
2565 }
2566 BUG_ON(btrfs_header_nritems(b) == 1);
2567 }
2568 return 0;
2569
2570again:
2571 ret = -EAGAIN;
2572done:
2573 return ret;
2574}
2575
2576static int key_search(struct extent_buffer *b, const struct btrfs_key *key,
2577 int level, int *prev_cmp, int *slot)
2578{
2579 if (*prev_cmp != 0) {
2580 *prev_cmp = btrfs_bin_search(b, key, level, slot);
2581 return *prev_cmp;
2582 }
2583
2584 *slot = 0;
2585
2586 return 0;
2587}
2588
2589int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
2590 u64 iobjectid, u64 ioff, u8 key_type,
2591 struct btrfs_key *found_key)
2592{
2593 int ret;
2594 struct btrfs_key key;
2595 struct extent_buffer *eb;
2596
2597 ASSERT(path);
2598 ASSERT(found_key);
2599
2600 key.type = key_type;
2601 key.objectid = iobjectid;
2602 key.offset = ioff;
2603
2604 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
2605 if (ret < 0)
2606 return ret;
2607
2608 eb = path->nodes[0];
2609 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
2610 ret = btrfs_next_leaf(fs_root, path);
2611 if (ret)
2612 return ret;
2613 eb = path->nodes[0];
2614 }
2615
2616 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
2617 if (found_key->type != key.type ||
2618 found_key->objectid != key.objectid)
2619 return 1;
2620
2621 return 0;
2622}
2623
2624static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
2625 struct btrfs_path *p,
2626 int write_lock_level)
2627{
2628 struct btrfs_fs_info *fs_info = root->fs_info;
2629 struct extent_buffer *b;
2630 int root_lock;
2631 int level = 0;
2632
2633 /* We try very hard to do read locks on the root */
2634 root_lock = BTRFS_READ_LOCK;
2635
2636 if (p->search_commit_root) {
2637 /*
2638 * The commit roots are read only so we always do read locks,
2639 * and we always must hold the commit_root_sem when doing
2640 * searches on them, the only exception is send where we don't
2641 * want to block transaction commits for a long time, so
2642 * we need to clone the commit root in order to avoid races
2643 * with transaction commits that create a snapshot of one of
2644 * the roots used by a send operation.
2645 */
2646 if (p->need_commit_sem) {
2647 down_read(&fs_info->commit_root_sem);
2648 b = btrfs_clone_extent_buffer(root->commit_root);
2649 up_read(&fs_info->commit_root_sem);
2650 if (!b)
2651 return ERR_PTR(-ENOMEM);
2652
2653 } else {
2654 b = root->commit_root;
2655 extent_buffer_get(b);
2656 }
2657 level = btrfs_header_level(b);
2658 /*
2659 * Ensure that all callers have set skip_locking when
2660 * p->search_commit_root = 1.
2661 */
2662 ASSERT(p->skip_locking == 1);
2663
2664 goto out;
2665 }
2666
2667 if (p->skip_locking) {
2668 b = btrfs_root_node(root);
2669 level = btrfs_header_level(b);
2670 goto out;
2671 }
2672
2673 /*
2674 * If the level is set to maximum, we can skip trying to get the read
2675 * lock.
2676 */
2677 if (write_lock_level < BTRFS_MAX_LEVEL) {
2678 /*
2679 * We don't know the level of the root node until we actually
2680 * have it read locked
2681 */
2682 b = btrfs_read_lock_root_node(root);
2683 level = btrfs_header_level(b);
2684 if (level > write_lock_level)
2685 goto out;
2686
2687 /* Whoops, must trade for write lock */
2688 btrfs_tree_read_unlock(b);
2689 free_extent_buffer(b);
2690 }
2691
2692 b = btrfs_lock_root_node(root);
2693 root_lock = BTRFS_WRITE_LOCK;
2694
2695 /* The level might have changed, check again */
2696 level = btrfs_header_level(b);
2697
2698out:
2699 p->nodes[level] = b;
2700 if (!p->skip_locking)
2701 p->locks[level] = root_lock;
2702 /*
2703 * Callers are responsible for dropping b's references.
2704 */
2705 return b;
2706}
2707
2708
2709/*
2710 * btrfs_search_slot - look for a key in a tree and perform necessary
2711 * modifications to preserve tree invariants.
2712 *
2713 * @trans: Handle of transaction, used when modifying the tree
2714 * @p: Holds all btree nodes along the search path
2715 * @root: The root node of the tree
2716 * @key: The key we are looking for
2717 * @ins_len: Indicates purpose of search, for inserts it is 1, for
2718 * deletions it's -1. 0 for plain searches
2719 * @cow: boolean should CoW operations be performed. Must always be 1
2720 * when modifying the tree.
2721 *
2722 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
2723 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
2724 *
2725 * If @key is found, 0 is returned and you can find the item in the leaf level
2726 * of the path (level 0)
2727 *
2728 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
2729 * points to the slot where it should be inserted
2730 *
2731 * If an error is encountered while searching the tree a negative error number
2732 * is returned
2733 */
2734int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2735 const struct btrfs_key *key, struct btrfs_path *p,
2736 int ins_len, int cow)
2737{
2738 struct extent_buffer *b;
2739 int slot;
2740 int ret;
2741 int err;
2742 int level;
2743 int lowest_unlock = 1;
2744 /* everything at write_lock_level or lower must be write locked */
2745 int write_lock_level = 0;
2746 u8 lowest_level = 0;
2747 int min_write_lock_level;
2748 int prev_cmp;
2749
2750 lowest_level = p->lowest_level;
2751 WARN_ON(lowest_level && ins_len > 0);
2752 WARN_ON(p->nodes[0] != NULL);
2753 BUG_ON(!cow && ins_len);
2754
2755 if (ins_len < 0) {
2756 lowest_unlock = 2;
2757
2758 /* when we are removing items, we might have to go up to level
2759 * two as we update tree pointers Make sure we keep write
2760 * for those levels as well
2761 */
2762 write_lock_level = 2;
2763 } else if (ins_len > 0) {
2764 /*
2765 * for inserting items, make sure we have a write lock on
2766 * level 1 so we can update keys
2767 */
2768 write_lock_level = 1;
2769 }
2770
2771 if (!cow)
2772 write_lock_level = -1;
2773
2774 if (cow && (p->keep_locks || p->lowest_level))
2775 write_lock_level = BTRFS_MAX_LEVEL;
2776
2777 min_write_lock_level = write_lock_level;
2778
2779again:
2780 prev_cmp = -1;
2781 b = btrfs_search_slot_get_root(root, p, write_lock_level);
2782 if (IS_ERR(b)) {
2783 ret = PTR_ERR(b);
2784 goto done;
2785 }
2786
2787 while (b) {
2788 level = btrfs_header_level(b);
2789
2790 /*
2791 * setup the path here so we can release it under lock
2792 * contention with the cow code
2793 */
2794 if (cow) {
2795 bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2796
2797 /*
2798 * if we don't really need to cow this block
2799 * then we don't want to set the path blocking,
2800 * so we test it here
2801 */
2802 if (!should_cow_block(trans, root, b)) {
2803 trans->dirty = true;
2804 goto cow_done;
2805 }
2806
2807 /*
2808 * must have write locks on this node and the
2809 * parent
2810 */
2811 if (level > write_lock_level ||
2812 (level + 1 > write_lock_level &&
2813 level + 1 < BTRFS_MAX_LEVEL &&
2814 p->nodes[level + 1])) {
2815 write_lock_level = level + 1;
2816 btrfs_release_path(p);
2817 goto again;
2818 }
2819
2820 btrfs_set_path_blocking(p);
2821 if (last_level)
2822 err = btrfs_cow_block(trans, root, b, NULL, 0,
2823 &b);
2824 else
2825 err = btrfs_cow_block(trans, root, b,
2826 p->nodes[level + 1],
2827 p->slots[level + 1], &b);
2828 if (err) {
2829 ret = err;
2830 goto done;
2831 }
2832 }
2833cow_done:
2834 p->nodes[level] = b;
2835 /*
2836 * Leave path with blocking locks to avoid massive
2837 * lock context switch, this is made on purpose.
2838 */
2839
2840 /*
2841 * we have a lock on b and as long as we aren't changing
2842 * the tree, there is no way to for the items in b to change.
2843 * It is safe to drop the lock on our parent before we
2844 * go through the expensive btree search on b.
2845 *
2846 * If we're inserting or deleting (ins_len != 0), then we might
2847 * be changing slot zero, which may require changing the parent.
2848 * So, we can't drop the lock until after we know which slot
2849 * we're operating on.
2850 */
2851 if (!ins_len && !p->keep_locks) {
2852 int u = level + 1;
2853
2854 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2855 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2856 p->locks[u] = 0;
2857 }
2858 }
2859
2860 ret = key_search(b, key, level, &prev_cmp, &slot);
2861 if (ret < 0)
2862 goto done;
2863
2864 if (level != 0) {
2865 int dec = 0;
2866 if (ret && slot > 0) {
2867 dec = 1;
2868 slot -= 1;
2869 }
2870 p->slots[level] = slot;
2871 err = setup_nodes_for_search(trans, root, p, b, level,
2872 ins_len, &write_lock_level);
2873 if (err == -EAGAIN)
2874 goto again;
2875 if (err) {
2876 ret = err;
2877 goto done;
2878 }
2879 b = p->nodes[level];
2880 slot = p->slots[level];
2881
2882 /*
2883 * slot 0 is special, if we change the key
2884 * we have to update the parent pointer
2885 * which means we must have a write lock
2886 * on the parent
2887 */
2888 if (slot == 0 && ins_len &&
2889 write_lock_level < level + 1) {
2890 write_lock_level = level + 1;
2891 btrfs_release_path(p);
2892 goto again;
2893 }
2894
2895 unlock_up(p, level, lowest_unlock,
2896 min_write_lock_level, &write_lock_level);
2897
2898 if (level == lowest_level) {
2899 if (dec)
2900 p->slots[level]++;
2901 goto done;
2902 }
2903
2904 err = read_block_for_search(root, p, &b, level,
2905 slot, key);
2906 if (err == -EAGAIN)
2907 goto again;
2908 if (err) {
2909 ret = err;
2910 goto done;
2911 }
2912
2913 if (!p->skip_locking) {
2914 level = btrfs_header_level(b);
2915 if (level <= write_lock_level) {
2916 if (!btrfs_try_tree_write_lock(b)) {
2917 btrfs_set_path_blocking(p);
2918 btrfs_tree_lock(b);
2919 }
2920 p->locks[level] = BTRFS_WRITE_LOCK;
2921 } else {
2922 if (!btrfs_tree_read_lock_atomic(b)) {
2923 btrfs_set_path_blocking(p);
2924 btrfs_tree_read_lock(b);
2925 }
2926 p->locks[level] = BTRFS_READ_LOCK;
2927 }
2928 p->nodes[level] = b;
2929 }
2930 } else {
2931 p->slots[level] = slot;
2932 if (ins_len > 0 &&
2933 btrfs_leaf_free_space(b) < ins_len) {
2934 if (write_lock_level < 1) {
2935 write_lock_level = 1;
2936 btrfs_release_path(p);
2937 goto again;
2938 }
2939
2940 btrfs_set_path_blocking(p);
2941 err = split_leaf(trans, root, key,
2942 p, ins_len, ret == 0);
2943
2944 BUG_ON(err > 0);
2945 if (err) {
2946 ret = err;
2947 goto done;
2948 }
2949 }
2950 if (!p->search_for_split)
2951 unlock_up(p, level, lowest_unlock,
2952 min_write_lock_level, NULL);
2953 goto done;
2954 }
2955 }
2956 ret = 1;
2957done:
2958 /*
2959 * we don't really know what they plan on doing with the path
2960 * from here on, so for now just mark it as blocking
2961 */
2962 if (!p->leave_spinning)
2963 btrfs_set_path_blocking(p);
2964 if (ret < 0 && !p->skip_release_on_error)
2965 btrfs_release_path(p);
2966 return ret;
2967}
2968
2969/*
2970 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2971 * current state of the tree together with the operations recorded in the tree
2972 * modification log to search for the key in a previous version of this tree, as
2973 * denoted by the time_seq parameter.
2974 *
2975 * Naturally, there is no support for insert, delete or cow operations.
2976 *
2977 * The resulting path and return value will be set up as if we called
2978 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2979 */
2980int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2981 struct btrfs_path *p, u64 time_seq)
2982{
2983 struct btrfs_fs_info *fs_info = root->fs_info;
2984 struct extent_buffer *b;
2985 int slot;
2986 int ret;
2987 int err;
2988 int level;
2989 int lowest_unlock = 1;
2990 u8 lowest_level = 0;
2991 int prev_cmp = -1;
2992
2993 lowest_level = p->lowest_level;
2994 WARN_ON(p->nodes[0] != NULL);
2995
2996 if (p->search_commit_root) {
2997 BUG_ON(time_seq);
2998 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2999 }
3000
3001again:
3002 b = get_old_root(root, time_seq);
3003 if (!b) {
3004 ret = -EIO;
3005 goto done;
3006 }
3007 level = btrfs_header_level(b);
3008 p->locks[level] = BTRFS_READ_LOCK;
3009
3010 while (b) {
3011 level = btrfs_header_level(b);
3012 p->nodes[level] = b;
3013
3014 /*
3015 * we have a lock on b and as long as we aren't changing
3016 * the tree, there is no way to for the items in b to change.
3017 * It is safe to drop the lock on our parent before we
3018 * go through the expensive btree search on b.
3019 */
3020 btrfs_unlock_up_safe(p, level + 1);
3021
3022 /*
3023 * Since we can unwind ebs we want to do a real search every
3024 * time.
3025 */
3026 prev_cmp = -1;
3027 ret = key_search(b, key, level, &prev_cmp, &slot);
3028 if (ret < 0)
3029 goto done;
3030
3031 if (level != 0) {
3032 int dec = 0;
3033 if (ret && slot > 0) {
3034 dec = 1;
3035 slot -= 1;
3036 }
3037 p->slots[level] = slot;
3038 unlock_up(p, level, lowest_unlock, 0, NULL);
3039
3040 if (level == lowest_level) {
3041 if (dec)
3042 p->slots[level]++;
3043 goto done;
3044 }
3045
3046 err = read_block_for_search(root, p, &b, level,
3047 slot, key);
3048 if (err == -EAGAIN)
3049 goto again;
3050 if (err) {
3051 ret = err;
3052 goto done;
3053 }
3054
3055 level = btrfs_header_level(b);
3056 if (!btrfs_tree_read_lock_atomic(b)) {
3057 btrfs_set_path_blocking(p);
3058 btrfs_tree_read_lock(b);
3059 }
3060 b = tree_mod_log_rewind(fs_info, p, b, time_seq);
3061 if (!b) {
3062 ret = -ENOMEM;
3063 goto done;
3064 }
3065 p->locks[level] = BTRFS_READ_LOCK;
3066 p->nodes[level] = b;
3067 } else {
3068 p->slots[level] = slot;
3069 unlock_up(p, level, lowest_unlock, 0, NULL);
3070 goto done;
3071 }
3072 }
3073 ret = 1;
3074done:
3075 if (!p->leave_spinning)
3076 btrfs_set_path_blocking(p);
3077 if (ret < 0)
3078 btrfs_release_path(p);
3079
3080 return ret;
3081}
3082
3083/*
3084 * helper to use instead of search slot if no exact match is needed but
3085 * instead the next or previous item should be returned.
3086 * When find_higher is true, the next higher item is returned, the next lower
3087 * otherwise.
3088 * When return_any and find_higher are both true, and no higher item is found,
3089 * return the next lower instead.
3090 * When return_any is true and find_higher is false, and no lower item is found,
3091 * return the next higher instead.
3092 * It returns 0 if any item is found, 1 if none is found (tree empty), and
3093 * < 0 on error
3094 */
3095int btrfs_search_slot_for_read(struct btrfs_root *root,
3096 const struct btrfs_key *key,
3097 struct btrfs_path *p, int find_higher,
3098 int return_any)
3099{
3100 int ret;
3101 struct extent_buffer *leaf;
3102
3103again:
3104 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
3105 if (ret <= 0)
3106 return ret;
3107 /*
3108 * a return value of 1 means the path is at the position where the
3109 * item should be inserted. Normally this is the next bigger item,
3110 * but in case the previous item is the last in a leaf, path points
3111 * to the first free slot in the previous leaf, i.e. at an invalid
3112 * item.
3113 */
3114 leaf = p->nodes[0];
3115
3116 if (find_higher) {
3117 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
3118 ret = btrfs_next_leaf(root, p);
3119 if (ret <= 0)
3120 return ret;
3121 if (!return_any)
3122 return 1;
3123 /*
3124 * no higher item found, return the next
3125 * lower instead
3126 */
3127 return_any = 0;
3128 find_higher = 0;
3129 btrfs_release_path(p);
3130 goto again;
3131 }
3132 } else {
3133 if (p->slots[0] == 0) {
3134 ret = btrfs_prev_leaf(root, p);
3135 if (ret < 0)
3136 return ret;
3137 if (!ret) {
3138 leaf = p->nodes[0];
3139 if (p->slots[0] == btrfs_header_nritems(leaf))
3140 p->slots[0]--;
3141 return 0;
3142 }
3143 if (!return_any)
3144 return 1;
3145 /*
3146 * no lower item found, return the next
3147 * higher instead
3148 */
3149 return_any = 0;
3150 find_higher = 1;
3151 btrfs_release_path(p);
3152 goto again;
3153 } else {
3154 --p->slots[0];
3155 }
3156 }
3157 return 0;
3158}
3159
3160/*
3161 * adjust the pointers going up the tree, starting at level
3162 * making sure the right key of each node is points to 'key'.
3163 * This is used after shifting pointers to the left, so it stops
3164 * fixing up pointers when a given leaf/node is not in slot 0 of the
3165 * higher levels
3166 *
3167 */
3168static void fixup_low_keys(struct btrfs_path *path,
3169 struct btrfs_disk_key *key, int level)
3170{
3171 int i;
3172 struct extent_buffer *t;
3173 int ret;
3174
3175 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
3176 int tslot = path->slots[i];
3177
3178 if (!path->nodes[i])
3179 break;
3180 t = path->nodes[i];
3181 ret = tree_mod_log_insert_key(t, tslot, MOD_LOG_KEY_REPLACE,
3182 GFP_ATOMIC);
3183 BUG_ON(ret < 0);
3184 btrfs_set_node_key(t, key, tslot);
3185 btrfs_mark_buffer_dirty(path->nodes[i]);
3186 if (tslot != 0)
3187 break;
3188 }
3189}
3190
3191/*
3192 * update item key.
3193 *
3194 * This function isn't completely safe. It's the caller's responsibility
3195 * that the new key won't break the order
3196 */
3197void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
3198 struct btrfs_path *path,
3199 const struct btrfs_key *new_key)
3200{
3201 struct btrfs_disk_key disk_key;
3202 struct extent_buffer *eb;
3203 int slot;
3204
3205 eb = path->nodes[0];
3206 slot = path->slots[0];
3207 if (slot > 0) {
3208 btrfs_item_key(eb, &disk_key, slot - 1);
3209 if (unlikely(comp_keys(&disk_key, new_key) >= 0)) {
3210 btrfs_crit(fs_info,
3211 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
3212 slot, btrfs_disk_key_objectid(&disk_key),
3213 btrfs_disk_key_type(&disk_key),
3214 btrfs_disk_key_offset(&disk_key),
3215 new_key->objectid, new_key->type,
3216 new_key->offset);
3217 btrfs_print_leaf(eb);
3218 BUG();
3219 }
3220 }
3221 if (slot < btrfs_header_nritems(eb) - 1) {
3222 btrfs_item_key(eb, &disk_key, slot + 1);
3223 if (unlikely(comp_keys(&disk_key, new_key) <= 0)) {
3224 btrfs_crit(fs_info,
3225 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
3226 slot, btrfs_disk_key_objectid(&disk_key),
3227 btrfs_disk_key_type(&disk_key),
3228 btrfs_disk_key_offset(&disk_key),
3229 new_key->objectid, new_key->type,
3230 new_key->offset);
3231 btrfs_print_leaf(eb);
3232 BUG();
3233 }
3234 }
3235
3236 btrfs_cpu_key_to_disk(&disk_key, new_key);
3237 btrfs_set_item_key(eb, &disk_key, slot);
3238 btrfs_mark_buffer_dirty(eb);
3239 if (slot == 0)
3240 fixup_low_keys(path, &disk_key, 1);
3241}
3242
3243/*
3244 * try to push data from one node into the next node left in the
3245 * tree.
3246 *
3247 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
3248 * error, and > 0 if there was no room in the left hand block.
3249 */
3250static int push_node_left(struct btrfs_trans_handle *trans,
3251 struct extent_buffer *dst,
3252 struct extent_buffer *src, int empty)
3253{
3254 struct btrfs_fs_info *fs_info = trans->fs_info;
3255 int push_items = 0;
3256 int src_nritems;
3257 int dst_nritems;
3258 int ret = 0;
3259
3260 src_nritems = btrfs_header_nritems(src);
3261 dst_nritems = btrfs_header_nritems(dst);
3262 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
3263 WARN_ON(btrfs_header_generation(src) != trans->transid);
3264 WARN_ON(btrfs_header_generation(dst) != trans->transid);
3265
3266 if (!empty && src_nritems <= 8)
3267 return 1;
3268
3269 if (push_items <= 0)
3270 return 1;
3271
3272 if (empty) {
3273 push_items = min(src_nritems, push_items);
3274 if (push_items < src_nritems) {
3275 /* leave at least 8 pointers in the node if
3276 * we aren't going to empty it
3277 */
3278 if (src_nritems - push_items < 8) {
3279 if (push_items <= 8)
3280 return 1;
3281 push_items -= 8;
3282 }
3283 }
3284 } else
3285 push_items = min(src_nritems - 8, push_items);
3286
3287 ret = tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
3288 if (ret) {
3289 btrfs_abort_transaction(trans, ret);
3290 return ret;
3291 }
3292 copy_extent_buffer(dst, src,
3293 btrfs_node_key_ptr_offset(dst_nritems),
3294 btrfs_node_key_ptr_offset(0),
3295 push_items * sizeof(struct btrfs_key_ptr));
3296
3297 if (push_items < src_nritems) {
3298 /*
3299 * Don't call tree_mod_log_insert_move here, key removal was
3300 * already fully logged by tree_mod_log_eb_copy above.
3301 */
3302 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
3303 btrfs_node_key_ptr_offset(push_items),
3304 (src_nritems - push_items) *
3305 sizeof(struct btrfs_key_ptr));
3306 }
3307 btrfs_set_header_nritems(src, src_nritems - push_items);
3308 btrfs_set_header_nritems(dst, dst_nritems + push_items);
3309 btrfs_mark_buffer_dirty(src);
3310 btrfs_mark_buffer_dirty(dst);
3311
3312 return ret;
3313}
3314
3315/*
3316 * try to push data from one node into the next node right in the
3317 * tree.
3318 *
3319 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
3320 * error, and > 0 if there was no room in the right hand block.
3321 *
3322 * this will only push up to 1/2 the contents of the left node over
3323 */
3324static int balance_node_right(struct btrfs_trans_handle *trans,
3325 struct extent_buffer *dst,
3326 struct extent_buffer *src)
3327{
3328 struct btrfs_fs_info *fs_info = trans->fs_info;
3329 int push_items = 0;
3330 int max_push;
3331 int src_nritems;
3332 int dst_nritems;
3333 int ret = 0;
3334
3335 WARN_ON(btrfs_header_generation(src) != trans->transid);
3336 WARN_ON(btrfs_header_generation(dst) != trans->transid);
3337
3338 src_nritems = btrfs_header_nritems(src);
3339 dst_nritems = btrfs_header_nritems(dst);
3340 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
3341 if (push_items <= 0)
3342 return 1;
3343
3344 if (src_nritems < 4)
3345 return 1;
3346
3347 max_push = src_nritems / 2 + 1;
3348 /* don't try to empty the node */
3349 if (max_push >= src_nritems)
3350 return 1;
3351
3352 if (max_push < push_items)
3353 push_items = max_push;
3354
3355 ret = tree_mod_log_insert_move(dst, push_items, 0, dst_nritems);
3356 BUG_ON(ret < 0);
3357 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
3358 btrfs_node_key_ptr_offset(0),
3359 (dst_nritems) *
3360 sizeof(struct btrfs_key_ptr));
3361
3362 ret = tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
3363 push_items);
3364 if (ret) {
3365 btrfs_abort_transaction(trans, ret);
3366 return ret;
3367 }
3368 copy_extent_buffer(dst, src,
3369 btrfs_node_key_ptr_offset(0),
3370 btrfs_node_key_ptr_offset(src_nritems - push_items),
3371 push_items * sizeof(struct btrfs_key_ptr));
3372
3373 btrfs_set_header_nritems(src, src_nritems - push_items);
3374 btrfs_set_header_nritems(dst, dst_nritems + push_items);
3375
3376 btrfs_mark_buffer_dirty(src);
3377 btrfs_mark_buffer_dirty(dst);
3378
3379 return ret;
3380}
3381
3382/*
3383 * helper function to insert a new root level in the tree.
3384 * A new node is allocated, and a single item is inserted to
3385 * point to the existing root
3386 *
3387 * returns zero on success or < 0 on failure.
3388 */
3389static noinline int insert_new_root(struct btrfs_trans_handle *trans,
3390 struct btrfs_root *root,
3391 struct btrfs_path *path, int level)
3392{
3393 struct btrfs_fs_info *fs_info = root->fs_info;
3394 u64 lower_gen;
3395 struct extent_buffer *lower;
3396 struct extent_buffer *c;
3397 struct extent_buffer *old;
3398 struct btrfs_disk_key lower_key;
3399 int ret;
3400
3401 BUG_ON(path->nodes[level]);
3402 BUG_ON(path->nodes[level-1] != root->node);
3403
3404 lower = path->nodes[level-1];
3405 if (level == 1)
3406 btrfs_item_key(lower, &lower_key, 0);
3407 else
3408 btrfs_node_key(lower, &lower_key, 0);
3409
3410 c = alloc_tree_block_no_bg_flush(trans, root, 0, &lower_key, level,
3411 root->node->start, 0);
3412 if (IS_ERR(c))
3413 return PTR_ERR(c);
3414
3415 root_add_used(root, fs_info->nodesize);
3416
3417 btrfs_set_header_nritems(c, 1);
3418 btrfs_set_node_key(c, &lower_key, 0);
3419 btrfs_set_node_blockptr(c, 0, lower->start);
3420 lower_gen = btrfs_header_generation(lower);
3421 WARN_ON(lower_gen != trans->transid);
3422
3423 btrfs_set_node_ptr_generation(c, 0, lower_gen);
3424
3425 btrfs_mark_buffer_dirty(c);
3426
3427 old = root->node;
3428 ret = tree_mod_log_insert_root(root->node, c, 0);
3429 BUG_ON(ret < 0);
3430 rcu_assign_pointer(root->node, c);
3431
3432 /* the super has an extra ref to root->node */
3433 free_extent_buffer(old);
3434
3435 add_root_to_dirty_list(root);
3436 extent_buffer_get(c);
3437 path->nodes[level] = c;
3438 path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
3439 path->slots[level] = 0;
3440 return 0;
3441}
3442
3443/*
3444 * worker function to insert a single pointer in a node.
3445 * the node should have enough room for the pointer already
3446 *
3447 * slot and level indicate where you want the key to go, and
3448 * blocknr is the block the key points to.
3449 */
3450static void insert_ptr(struct btrfs_trans_handle *trans,
3451 struct btrfs_path *path,
3452 struct btrfs_disk_key *key, u64 bytenr,
3453 int slot, int level)
3454{
3455 struct extent_buffer *lower;
3456 int nritems;
3457 int ret;
3458
3459 BUG_ON(!path->nodes[level]);
3460 btrfs_assert_tree_locked(path->nodes[level]);
3461 lower = path->nodes[level];
3462 nritems = btrfs_header_nritems(lower);
3463 BUG_ON(slot > nritems);
3464 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
3465 if (slot != nritems) {
3466 if (level) {
3467 ret = tree_mod_log_insert_move(lower, slot + 1, slot,
3468 nritems - slot);
3469 BUG_ON(ret < 0);
3470 }
3471 memmove_extent_buffer(lower,
3472 btrfs_node_key_ptr_offset(slot + 1),
3473 btrfs_node_key_ptr_offset(slot),
3474 (nritems - slot) * sizeof(struct btrfs_key_ptr));
3475 }
3476 if (level) {
3477 ret = tree_mod_log_insert_key(lower, slot, MOD_LOG_KEY_ADD,
3478 GFP_NOFS);
3479 BUG_ON(ret < 0);
3480 }
3481 btrfs_set_node_key(lower, key, slot);
3482 btrfs_set_node_blockptr(lower, slot, bytenr);
3483 WARN_ON(trans->transid == 0);
3484 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3485 btrfs_set_header_nritems(lower, nritems + 1);
3486 btrfs_mark_buffer_dirty(lower);
3487}
3488
3489/*
3490 * split the node at the specified level in path in two.
3491 * The path is corrected to point to the appropriate node after the split
3492 *
3493 * Before splitting this tries to make some room in the node by pushing
3494 * left and right, if either one works, it returns right away.
3495 *
3496 * returns 0 on success and < 0 on failure
3497 */
3498static noinline int split_node(struct btrfs_trans_handle *trans,
3499 struct btrfs_root *root,
3500 struct btrfs_path *path, int level)
3501{
3502 struct btrfs_fs_info *fs_info = root->fs_info;
3503 struct extent_buffer *c;
3504 struct extent_buffer *split;
3505 struct btrfs_disk_key disk_key;
3506 int mid;
3507 int ret;
3508 u32 c_nritems;
3509
3510 c = path->nodes[level];
3511 WARN_ON(btrfs_header_generation(c) != trans->transid);
3512 if (c == root->node) {
3513 /*
3514 * trying to split the root, lets make a new one
3515 *
3516 * tree mod log: We don't log_removal old root in
3517 * insert_new_root, because that root buffer will be kept as a
3518 * normal node. We are going to log removal of half of the
3519 * elements below with tree_mod_log_eb_copy. We're holding a
3520 * tree lock on the buffer, which is why we cannot race with
3521 * other tree_mod_log users.
3522 */
3523 ret = insert_new_root(trans, root, path, level + 1);
3524 if (ret)
3525 return ret;
3526 } else {
3527 ret = push_nodes_for_insert(trans, root, path, level);
3528 c = path->nodes[level];
3529 if (!ret && btrfs_header_nritems(c) <
3530 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
3531 return 0;
3532 if (ret < 0)
3533 return ret;
3534 }
3535
3536 c_nritems = btrfs_header_nritems(c);
3537 mid = (c_nritems + 1) / 2;
3538 btrfs_node_key(c, &disk_key, mid);
3539
3540 split = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, level,
3541 c->start, 0);
3542 if (IS_ERR(split))
3543 return PTR_ERR(split);
3544
3545 root_add_used(root, fs_info->nodesize);
3546 ASSERT(btrfs_header_level(c) == level);
3547
3548 ret = tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
3549 if (ret) {
3550 btrfs_abort_transaction(trans, ret);
3551 return ret;
3552 }
3553 copy_extent_buffer(split, c,
3554 btrfs_node_key_ptr_offset(0),
3555 btrfs_node_key_ptr_offset(mid),
3556 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3557 btrfs_set_header_nritems(split, c_nritems - mid);
3558 btrfs_set_header_nritems(c, mid);
3559 ret = 0;
3560
3561 btrfs_mark_buffer_dirty(c);
3562 btrfs_mark_buffer_dirty(split);
3563
3564 insert_ptr(trans, path, &disk_key, split->start,
3565 path->slots[level + 1] + 1, level + 1);
3566
3567 if (path->slots[level] >= mid) {
3568 path->slots[level] -= mid;
3569 btrfs_tree_unlock(c);
3570 free_extent_buffer(c);
3571 path->nodes[level] = split;
3572 path->slots[level + 1] += 1;
3573 } else {
3574 btrfs_tree_unlock(split);
3575 free_extent_buffer(split);
3576 }
3577 return ret;
3578}
3579
3580/*
3581 * how many bytes are required to store the items in a leaf. start
3582 * and nr indicate which items in the leaf to check. This totals up the
3583 * space used both by the item structs and the item data
3584 */
3585static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3586{
3587 struct btrfs_item *start_item;
3588 struct btrfs_item *end_item;
3589 struct btrfs_map_token token;
3590 int data_len;
3591 int nritems = btrfs_header_nritems(l);
3592 int end = min(nritems, start + nr) - 1;
3593
3594 if (!nr)
3595 return 0;
3596 btrfs_init_map_token(&token, l);
3597 start_item = btrfs_item_nr(start);
3598 end_item = btrfs_item_nr(end);
3599 data_len = btrfs_token_item_offset(l, start_item, &token) +
3600 btrfs_token_item_size(l, start_item, &token);
3601 data_len = data_len - btrfs_token_item_offset(l, end_item, &token);
3602 data_len += sizeof(struct btrfs_item) * nr;
3603 WARN_ON(data_len < 0);
3604 return data_len;
3605}
3606
3607/*
3608 * The space between the end of the leaf items and
3609 * the start of the leaf data. IOW, how much room
3610 * the leaf has left for both items and data
3611 */
3612noinline int btrfs_leaf_free_space(struct extent_buffer *leaf)
3613{
3614 struct btrfs_fs_info *fs_info = leaf->fs_info;
3615 int nritems = btrfs_header_nritems(leaf);
3616 int ret;
3617
3618 ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
3619 if (ret < 0) {
3620 btrfs_crit(fs_info,
3621 "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3622 ret,
3623 (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
3624 leaf_space_used(leaf, 0, nritems), nritems);
3625 }
3626 return ret;
3627}
3628
3629/*
3630 * min slot controls the lowest index we're willing to push to the
3631 * right. We'll push up to and including min_slot, but no lower
3632 */
3633static noinline int __push_leaf_right(struct btrfs_path *path,
3634 int data_size, int empty,
3635 struct extent_buffer *right,
3636 int free_space, u32 left_nritems,
3637 u32 min_slot)
3638{
3639 struct btrfs_fs_info *fs_info = right->fs_info;
3640 struct extent_buffer *left = path->nodes[0];
3641 struct extent_buffer *upper = path->nodes[1];
3642 struct btrfs_map_token token;
3643 struct btrfs_disk_key disk_key;
3644 int slot;
3645 u32 i;
3646 int push_space = 0;
3647 int push_items = 0;
3648 struct btrfs_item *item;
3649 u32 nr;
3650 u32 right_nritems;
3651 u32 data_end;
3652 u32 this_item_size;
3653
3654 if (empty)
3655 nr = 0;
3656 else
3657 nr = max_t(u32, 1, min_slot);
3658
3659 if (path->slots[0] >= left_nritems)
3660 push_space += data_size;
3661
3662 slot = path->slots[1];
3663 i = left_nritems - 1;
3664 while (i >= nr) {
3665 item = btrfs_item_nr(i);
3666
3667 if (!empty && push_items > 0) {
3668 if (path->slots[0] > i)
3669 break;
3670 if (path->slots[0] == i) {
3671 int space = btrfs_leaf_free_space(left);
3672
3673 if (space + push_space * 2 > free_space)
3674 break;
3675 }
3676 }
3677
3678 if (path->slots[0] == i)
3679 push_space += data_size;
3680
3681 this_item_size = btrfs_item_size(left, item);
3682 if (this_item_size + sizeof(*item) + push_space > free_space)
3683 break;
3684
3685 push_items++;
3686 push_space += this_item_size + sizeof(*item);
3687 if (i == 0)
3688 break;
3689 i--;
3690 }
3691
3692 if (push_items == 0)
3693 goto out_unlock;
3694
3695 WARN_ON(!empty && push_items == left_nritems);
3696
3697 /* push left to right */
3698 right_nritems = btrfs_header_nritems(right);
3699
3700 push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3701 push_space -= leaf_data_end(left);
3702
3703 /* make room in the right data area */
3704 data_end = leaf_data_end(right);
3705 memmove_extent_buffer(right,
3706 BTRFS_LEAF_DATA_OFFSET + data_end - push_space,
3707 BTRFS_LEAF_DATA_OFFSET + data_end,
3708 BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
3709
3710 /* copy from the left data area */
3711 copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET +
3712 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3713 BTRFS_LEAF_DATA_OFFSET + leaf_data_end(left),
3714 push_space);
3715
3716 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3717 btrfs_item_nr_offset(0),
3718 right_nritems * sizeof(struct btrfs_item));
3719
3720 /* copy the items from left to right */
3721 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3722 btrfs_item_nr_offset(left_nritems - push_items),
3723 push_items * sizeof(struct btrfs_item));
3724
3725 /* update the item pointers */
3726 btrfs_init_map_token(&token, right);
3727 right_nritems += push_items;
3728 btrfs_set_header_nritems(right, right_nritems);
3729 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3730 for (i = 0; i < right_nritems; i++) {
3731 item = btrfs_item_nr(i);
3732 push_space -= btrfs_token_item_size(right, item, &token);
3733 btrfs_set_token_item_offset(right, item, push_space, &token);
3734 }
3735
3736 left_nritems -= push_items;
3737 btrfs_set_header_nritems(left, left_nritems);
3738
3739 if (left_nritems)
3740 btrfs_mark_buffer_dirty(left);
3741 else
3742 btrfs_clean_tree_block(left);
3743
3744 btrfs_mark_buffer_dirty(right);
3745
3746 btrfs_item_key(right, &disk_key, 0);
3747 btrfs_set_node_key(upper, &disk_key, slot + 1);
3748 btrfs_mark_buffer_dirty(upper);
3749
3750 /* then fixup the leaf pointer in the path */
3751 if (path->slots[0] >= left_nritems) {
3752 path->slots[0] -= left_nritems;
3753 if (btrfs_header_nritems(path->nodes[0]) == 0)
3754 btrfs_clean_tree_block(path->nodes[0]);
3755 btrfs_tree_unlock(path->nodes[0]);
3756 free_extent_buffer(path->nodes[0]);
3757 path->nodes[0] = right;
3758 path->slots[1] += 1;
3759 } else {
3760 btrfs_tree_unlock(right);
3761 free_extent_buffer(right);
3762 }
3763 return 0;
3764
3765out_unlock:
3766 btrfs_tree_unlock(right);
3767 free_extent_buffer(right);
3768 return 1;
3769}
3770
3771/*
3772 * push some data in the path leaf to the right, trying to free up at
3773 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3774 *
3775 * returns 1 if the push failed because the other node didn't have enough
3776 * room, 0 if everything worked out and < 0 if there were major errors.
3777 *
3778 * this will push starting from min_slot to the end of the leaf. It won't
3779 * push any slot lower than min_slot
3780 */
3781static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3782 *root, struct btrfs_path *path,
3783 int min_data_size, int data_size,
3784 int empty, u32 min_slot)
3785{
3786 struct extent_buffer *left = path->nodes[0];
3787 struct extent_buffer *right;
3788 struct extent_buffer *upper;
3789 int slot;
3790 int free_space;
3791 u32 left_nritems;
3792 int ret;
3793
3794 if (!path->nodes[1])
3795 return 1;
3796
3797 slot = path->slots[1];
3798 upper = path->nodes[1];
3799 if (slot >= btrfs_header_nritems(upper) - 1)
3800 return 1;
3801
3802 btrfs_assert_tree_locked(path->nodes[1]);
3803
3804 right = btrfs_read_node_slot(upper, slot + 1);
3805 /*
3806 * slot + 1 is not valid or we fail to read the right node,
3807 * no big deal, just return.
3808 */
3809 if (IS_ERR(right))
3810 return 1;
3811
3812 btrfs_tree_lock(right);
3813 btrfs_set_lock_blocking_write(right);
3814
3815 free_space = btrfs_leaf_free_space(right);
3816 if (free_space < data_size)
3817 goto out_unlock;
3818
3819 /* cow and double check */
3820 ret = btrfs_cow_block(trans, root, right, upper,
3821 slot + 1, &right);
3822 if (ret)
3823 goto out_unlock;
3824
3825 free_space = btrfs_leaf_free_space(right);
3826 if (free_space < data_size)
3827 goto out_unlock;
3828
3829 left_nritems = btrfs_header_nritems(left);
3830 if (left_nritems == 0)
3831 goto out_unlock;
3832
3833 if (path->slots[0] == left_nritems && !empty) {
3834 /* Key greater than all keys in the leaf, right neighbor has
3835 * enough room for it and we're not emptying our leaf to delete
3836 * it, therefore use right neighbor to insert the new item and
3837 * no need to touch/dirty our left leaf. */
3838 btrfs_tree_unlock(left);
3839 free_extent_buffer(left);
3840 path->nodes[0] = right;
3841 path->slots[0] = 0;
3842 path->slots[1]++;
3843 return 0;
3844 }
3845
3846 return __push_leaf_right(path, min_data_size, empty,
3847 right, free_space, left_nritems, min_slot);
3848out_unlock:
3849 btrfs_tree_unlock(right);
3850 free_extent_buffer(right);
3851 return 1;
3852}
3853
3854/*
3855 * push some data in the path leaf to the left, trying to free up at
3856 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3857 *
3858 * max_slot can put a limit on how far into the leaf we'll push items. The
3859 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3860 * items
3861 */
3862static noinline int __push_leaf_left(struct btrfs_path *path, int data_size,
3863 int empty, struct extent_buffer *left,
3864 int free_space, u32 right_nritems,
3865 u32 max_slot)
3866{
3867 struct btrfs_fs_info *fs_info = left->fs_info;
3868 struct btrfs_disk_key disk_key;
3869 struct extent_buffer *right = path->nodes[0];
3870 int i;
3871 int push_space = 0;
3872 int push_items = 0;
3873 struct btrfs_item *item;
3874 u32 old_left_nritems;
3875 u32 nr;
3876 int ret = 0;
3877 u32 this_item_size;
3878 u32 old_left_item_size;
3879 struct btrfs_map_token token;
3880
3881 if (empty)
3882 nr = min(right_nritems, max_slot);
3883 else
3884 nr = min(right_nritems - 1, max_slot);
3885
3886 for (i = 0; i < nr; i++) {
3887 item = btrfs_item_nr(i);
3888
3889 if (!empty && push_items > 0) {
3890 if (path->slots[0] < i)
3891 break;
3892 if (path->slots[0] == i) {
3893 int space = btrfs_leaf_free_space(right);
3894
3895 if (space + push_space * 2 > free_space)
3896 break;
3897 }
3898 }
3899
3900 if (path->slots[0] == i)
3901 push_space += data_size;
3902
3903 this_item_size = btrfs_item_size(right, item);
3904 if (this_item_size + sizeof(*item) + push_space > free_space)
3905 break;
3906
3907 push_items++;
3908 push_space += this_item_size + sizeof(*item);
3909 }
3910
3911 if (push_items == 0) {
3912 ret = 1;
3913 goto out;
3914 }
3915 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3916
3917 /* push data from right to left */
3918 copy_extent_buffer(left, right,
3919 btrfs_item_nr_offset(btrfs_header_nritems(left)),
3920 btrfs_item_nr_offset(0),
3921 push_items * sizeof(struct btrfs_item));
3922
3923 push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3924 btrfs_item_offset_nr(right, push_items - 1);
3925
3926 copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET +
3927 leaf_data_end(left) - push_space,
3928 BTRFS_LEAF_DATA_OFFSET +
3929 btrfs_item_offset_nr(right, push_items - 1),
3930 push_space);
3931 old_left_nritems = btrfs_header_nritems(left);
3932 BUG_ON(old_left_nritems <= 0);
3933
3934 btrfs_init_map_token(&token, left);
3935 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3936 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3937 u32 ioff;
3938
3939 item = btrfs_item_nr(i);
3940
3941 ioff = btrfs_token_item_offset(left, item, &token);
3942 btrfs_set_token_item_offset(left, item,
3943 ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size),
3944 &token);
3945 }
3946 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3947
3948 /* fixup right node */
3949 if (push_items > right_nritems)
3950 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3951 right_nritems);
3952
3953 if (push_items < right_nritems) {
3954 push_space = btrfs_item_offset_nr(right, push_items - 1) -
3955 leaf_data_end(right);
3956 memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET +
3957 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3958 BTRFS_LEAF_DATA_OFFSET +
3959 leaf_data_end(right), push_space);
3960
3961 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3962 btrfs_item_nr_offset(push_items),
3963 (btrfs_header_nritems(right) - push_items) *
3964 sizeof(struct btrfs_item));
3965 }
3966
3967 btrfs_init_map_token(&token, right);
3968 right_nritems -= push_items;
3969 btrfs_set_header_nritems(right, right_nritems);
3970 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3971 for (i = 0; i < right_nritems; i++) {
3972 item = btrfs_item_nr(i);
3973
3974 push_space = push_space - btrfs_token_item_size(right,
3975 item, &token);
3976 btrfs_set_token_item_offset(right, item, push_space, &token);
3977 }
3978
3979 btrfs_mark_buffer_dirty(left);
3980 if (right_nritems)
3981 btrfs_mark_buffer_dirty(right);
3982 else
3983 btrfs_clean_tree_block(right);
3984
3985 btrfs_item_key(right, &disk_key, 0);
3986 fixup_low_keys(path, &disk_key, 1);
3987
3988 /* then fixup the leaf pointer in the path */
3989 if (path->slots[0] < push_items) {
3990 path->slots[0] += old_left_nritems;
3991 btrfs_tree_unlock(path->nodes[0]);
3992 free_extent_buffer(path->nodes[0]);
3993 path->nodes[0] = left;
3994 path->slots[1] -= 1;
3995 } else {
3996 btrfs_tree_unlock(left);
3997 free_extent_buffer(left);
3998 path->slots[0] -= push_items;
3999 }
4000 BUG_ON(path->slots[0] < 0);
4001 return ret;
4002out:
4003 btrfs_tree_unlock(left);
4004 free_extent_buffer(left);
4005 return ret;
4006}
4007
4008/*
4009 * push some data in the path leaf to the left, trying to free up at
4010 * least data_size bytes. returns zero if the push worked, nonzero otherwise
4011 *
4012 * max_slot can put a limit on how far into the leaf we'll push items. The
4013 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
4014 * items
4015 */
4016static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
4017 *root, struct btrfs_path *path, int min_data_size,
4018 int data_size, int empty, u32 max_slot)
4019{
4020 struct extent_buffer *right = path->nodes[0];
4021 struct extent_buffer *left;
4022 int slot;
4023 int free_space;
4024 u32 right_nritems;
4025 int ret = 0;
4026
4027 slot = path->slots[1];
4028 if (slot == 0)
4029 return 1;
4030 if (!path->nodes[1])
4031 return 1;
4032
4033 right_nritems = btrfs_header_nritems(right);
4034 if (right_nritems == 0)
4035 return 1;
4036
4037 btrfs_assert_tree_locked(path->nodes[1]);
4038
4039 left = btrfs_read_node_slot(path->nodes[1], slot - 1);
4040 /*
4041 * slot - 1 is not valid or we fail to read the left node,
4042 * no big deal, just return.
4043 */
4044 if (IS_ERR(left))
4045 return 1;
4046
4047 btrfs_tree_lock(left);
4048 btrfs_set_lock_blocking_write(left);
4049
4050 free_space = btrfs_leaf_free_space(left);
4051 if (free_space < data_size) {
4052 ret = 1;
4053 goto out;
4054 }
4055
4056 /* cow and double check */
4057 ret = btrfs_cow_block(trans, root, left,
4058 path->nodes[1], slot - 1, &left);
4059 if (ret) {
4060 /* we hit -ENOSPC, but it isn't fatal here */
4061 if (ret == -ENOSPC)
4062 ret = 1;
4063 goto out;
4064 }
4065
4066 free_space = btrfs_leaf_free_space(left);
4067 if (free_space < data_size) {
4068 ret = 1;
4069 goto out;
4070 }
4071
4072 return __push_leaf_left(path, min_data_size,
4073 empty, left, free_space, right_nritems,
4074 max_slot);
4075out:
4076 btrfs_tree_unlock(left);
4077 free_extent_buffer(left);
4078 return ret;
4079}
4080
4081/*
4082 * split the path's leaf in two, making sure there is at least data_size
4083 * available for the resulting leaf level of the path.
4084 */
4085static noinline void copy_for_split(struct btrfs_trans_handle *trans,
4086 struct btrfs_path *path,
4087 struct extent_buffer *l,
4088 struct extent_buffer *right,
4089 int slot, int mid, int nritems)
4090{
4091 struct btrfs_fs_info *fs_info = trans->fs_info;
4092 int data_copy_size;
4093 int rt_data_off;
4094 int i;
4095 struct btrfs_disk_key disk_key;
4096 struct btrfs_map_token token;
4097
4098 nritems = nritems - mid;
4099 btrfs_set_header_nritems(right, nritems);
4100 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(l);
4101
4102 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
4103 btrfs_item_nr_offset(mid),
4104 nritems * sizeof(struct btrfs_item));
4105
4106 copy_extent_buffer(right, l,
4107 BTRFS_LEAF_DATA_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) -
4108 data_copy_size, BTRFS_LEAF_DATA_OFFSET +
4109 leaf_data_end(l), data_copy_size);
4110
4111 rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_end_nr(l, mid);
4112
4113 btrfs_init_map_token(&token, right);
4114 for (i = 0; i < nritems; i++) {
4115 struct btrfs_item *item = btrfs_item_nr(i);
4116 u32 ioff;
4117
4118 ioff = btrfs_token_item_offset(right, item, &token);
4119 btrfs_set_token_item_offset(right, item,
4120 ioff + rt_data_off, &token);
4121 }
4122
4123 btrfs_set_header_nritems(l, mid);
4124 btrfs_item_key(right, &disk_key, 0);
4125 insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
4126
4127 btrfs_mark_buffer_dirty(right);
4128 btrfs_mark_buffer_dirty(l);
4129 BUG_ON(path->slots[0] != slot);
4130
4131 if (mid <= slot) {
4132 btrfs_tree_unlock(path->nodes[0]);
4133 free_extent_buffer(path->nodes[0]);
4134 path->nodes[0] = right;
4135 path->slots[0] -= mid;
4136 path->slots[1] += 1;
4137 } else {
4138 btrfs_tree_unlock(right);
4139 free_extent_buffer(right);
4140 }
4141
4142 BUG_ON(path->slots[0] < 0);
4143}
4144
4145/*
4146 * double splits happen when we need to insert a big item in the middle
4147 * of a leaf. A double split can leave us with 3 mostly empty leaves:
4148 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
4149 * A B C
4150 *
4151 * We avoid this by trying to push the items on either side of our target
4152 * into the adjacent leaves. If all goes well we can avoid the double split
4153 * completely.
4154 */
4155static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
4156 struct btrfs_root *root,
4157 struct btrfs_path *path,
4158 int data_size)
4159{
4160 int ret;
4161 int progress = 0;
4162 int slot;
4163 u32 nritems;
4164 int space_needed = data_size;
4165
4166 slot = path->slots[0];
4167 if (slot < btrfs_header_nritems(path->nodes[0]))
4168 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
4169
4170 /*
4171 * try to push all the items after our slot into the
4172 * right leaf
4173 */
4174 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
4175 if (ret < 0)
4176 return ret;
4177
4178 if (ret == 0)
4179 progress++;
4180
4181 nritems = btrfs_header_nritems(path->nodes[0]);
4182 /*
4183 * our goal is to get our slot at the start or end of a leaf. If
4184 * we've done so we're done
4185 */
4186 if (path->slots[0] == 0 || path->slots[0] == nritems)
4187 return 0;
4188
4189 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
4190 return 0;
4191
4192 /* try to push all the items before our slot into the next leaf */
4193 slot = path->slots[0];
4194 space_needed = data_size;
4195 if (slot > 0)
4196 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
4197 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
4198 if (ret < 0)
4199 return ret;
4200
4201 if (ret == 0)
4202 progress++;
4203
4204 if (progress)
4205 return 0;
4206 return 1;
4207}
4208
4209/*
4210 * split the path's leaf in two, making sure there is at least data_size
4211 * available for the resulting leaf level of the path.
4212 *
4213 * returns 0 if all went well and < 0 on failure.
4214 */
4215static noinline int split_leaf(struct btrfs_trans_handle *trans,
4216 struct btrfs_root *root,
4217 const struct btrfs_key *ins_key,
4218 struct btrfs_path *path, int data_size,
4219 int extend)
4220{
4221 struct btrfs_disk_key disk_key;
4222 struct extent_buffer *l;
4223 u32 nritems;
4224 int mid;
4225 int slot;
4226 struct extent_buffer *right;
4227 struct btrfs_fs_info *fs_info = root->fs_info;
4228 int ret = 0;
4229 int wret;
4230 int split;
4231 int num_doubles = 0;
4232 int tried_avoid_double = 0;
4233
4234 l = path->nodes[0];
4235 slot = path->slots[0];
4236 if (extend && data_size + btrfs_item_size_nr(l, slot) +
4237 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
4238 return -EOVERFLOW;
4239
4240 /* first try to make some room by pushing left and right */
4241 if (data_size && path->nodes[1]) {
4242 int space_needed = data_size;
4243
4244 if (slot < btrfs_header_nritems(l))
4245 space_needed -= btrfs_leaf_free_space(l);
4246
4247 wret = push_leaf_right(trans, root, path, space_needed,
4248 space_needed, 0, 0);
4249 if (wret < 0)
4250 return wret;
4251 if (wret) {
4252 space_needed = data_size;
4253 if (slot > 0)
4254 space_needed -= btrfs_leaf_free_space(l);
4255 wret = push_leaf_left(trans, root, path, space_needed,
4256 space_needed, 0, (u32)-1);
4257 if (wret < 0)
4258 return wret;
4259 }
4260 l = path->nodes[0];
4261
4262 /* did the pushes work? */
4263 if (btrfs_leaf_free_space(l) >= data_size)
4264 return 0;
4265 }
4266
4267 if (!path->nodes[1]) {
4268 ret = insert_new_root(trans, root, path, 1);
4269 if (ret)
4270 return ret;
4271 }
4272again:
4273 split = 1;
4274 l = path->nodes[0];
4275 slot = path->slots[0];
4276 nritems = btrfs_header_nritems(l);
4277 mid = (nritems + 1) / 2;
4278
4279 if (mid <= slot) {
4280 if (nritems == 1 ||
4281 leaf_space_used(l, mid, nritems - mid) + data_size >
4282 BTRFS_LEAF_DATA_SIZE(fs_info)) {
4283 if (slot >= nritems) {
4284 split = 0;
4285 } else {
4286 mid = slot;
4287 if (mid != nritems &&
4288 leaf_space_used(l, mid, nritems - mid) +
4289 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4290 if (data_size && !tried_avoid_double)
4291 goto push_for_double;
4292 split = 2;
4293 }
4294 }
4295 }
4296 } else {
4297 if (leaf_space_used(l, 0, mid) + data_size >
4298 BTRFS_LEAF_DATA_SIZE(fs_info)) {
4299 if (!extend && data_size && slot == 0) {
4300 split = 0;
4301 } else if ((extend || !data_size) && slot == 0) {
4302 mid = 1;
4303 } else {
4304 mid = slot;
4305 if (mid != nritems &&
4306 leaf_space_used(l, mid, nritems - mid) +
4307 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4308 if (data_size && !tried_avoid_double)
4309 goto push_for_double;
4310 split = 2;
4311 }
4312 }
4313 }
4314 }
4315
4316 if (split == 0)
4317 btrfs_cpu_key_to_disk(&disk_key, ins_key);
4318 else
4319 btrfs_item_key(l, &disk_key, mid);
4320
4321 right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0,
4322 l->start, 0);
4323 if (IS_ERR(right))
4324 return PTR_ERR(right);
4325
4326 root_add_used(root, fs_info->nodesize);
4327
4328 if (split == 0) {
4329 if (mid <= slot) {
4330 btrfs_set_header_nritems(right, 0);
4331 insert_ptr(trans, path, &disk_key,
4332 right->start, path->slots[1] + 1, 1);
4333 btrfs_tree_unlock(path->nodes[0]);
4334 free_extent_buffer(path->nodes[0]);
4335 path->nodes[0] = right;
4336 path->slots[0] = 0;
4337 path->slots[1] += 1;
4338 } else {
4339 btrfs_set_header_nritems(right, 0);
4340 insert_ptr(trans, path, &disk_key,
4341 right->start, path->slots[1], 1);
4342 btrfs_tree_unlock(path->nodes[0]);
4343 free_extent_buffer(path->nodes[0]);
4344 path->nodes[0] = right;
4345 path->slots[0] = 0;
4346 if (path->slots[1] == 0)
4347 fixup_low_keys(path, &disk_key, 1);
4348 }
4349 /*
4350 * We create a new leaf 'right' for the required ins_len and
4351 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
4352 * the content of ins_len to 'right'.
4353 */
4354 return ret;
4355 }
4356
4357 copy_for_split(trans, path, l, right, slot, mid, nritems);
4358
4359 if (split == 2) {
4360 BUG_ON(num_doubles != 0);
4361 num_doubles++;
4362 goto again;
4363 }
4364
4365 return 0;
4366
4367push_for_double:
4368 push_for_double_split(trans, root, path, data_size);
4369 tried_avoid_double = 1;
4370 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
4371 return 0;
4372 goto again;
4373}
4374
4375static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
4376 struct btrfs_root *root,
4377 struct btrfs_path *path, int ins_len)
4378{
4379 struct btrfs_key key;
4380 struct extent_buffer *leaf;
4381 struct btrfs_file_extent_item *fi;
4382 u64 extent_len = 0;
4383 u32 item_size;
4384 int ret;
4385
4386 leaf = path->nodes[0];
4387 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4388
4389 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
4390 key.type != BTRFS_EXTENT_CSUM_KEY);
4391
4392 if (btrfs_leaf_free_space(leaf) >= ins_len)
4393 return 0;
4394
4395 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4396 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4397 fi = btrfs_item_ptr(leaf, path->slots[0],
4398 struct btrfs_file_extent_item);
4399 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
4400 }
4401 btrfs_release_path(path);
4402
4403 path->keep_locks = 1;
4404 path->search_for_split = 1;
4405 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
4406 path->search_for_split = 0;
4407 if (ret > 0)
4408 ret = -EAGAIN;
4409 if (ret < 0)
4410 goto err;
4411
4412 ret = -EAGAIN;
4413 leaf = path->nodes[0];
4414 /* if our item isn't there, return now */
4415 if (item_size != btrfs_item_size_nr(leaf, path->slots[0]))
4416 goto err;
4417
4418 /* the leaf has changed, it now has room. return now */
4419 if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
4420 goto err;
4421
4422 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4423 fi = btrfs_item_ptr(leaf, path->slots[0],
4424 struct btrfs_file_extent_item);
4425 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
4426 goto err;
4427 }
4428
4429 btrfs_set_path_blocking(path);
4430 ret = split_leaf(trans, root, &key, path, ins_len, 1);
4431 if (ret)
4432 goto err;
4433
4434 path->keep_locks = 0;
4435 btrfs_unlock_up_safe(path, 1);
4436 return 0;
4437err:
4438 path->keep_locks = 0;
4439 return ret;
4440}
4441
4442static noinline int split_item(struct btrfs_path *path,
4443 const struct btrfs_key *new_key,
4444 unsigned long split_offset)
4445{
4446 struct extent_buffer *leaf;
4447 struct btrfs_item *item;
4448 struct btrfs_item *new_item;
4449 int slot;
4450 char *buf;
4451 u32 nritems;
4452 u32 item_size;
4453 u32 orig_offset;
4454 struct btrfs_disk_key disk_key;
4455
4456 leaf = path->nodes[0];
4457 BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));
4458
4459 btrfs_set_path_blocking(path);
4460
4461 item = btrfs_item_nr(path->slots[0]);
4462 orig_offset = btrfs_item_offset(leaf, item);
4463 item_size = btrfs_item_size(leaf, item);
4464
4465 buf = kmalloc(item_size, GFP_NOFS);
4466 if (!buf)
4467 return -ENOMEM;
4468
4469 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
4470 path->slots[0]), item_size);
4471
4472 slot = path->slots[0] + 1;
4473 nritems = btrfs_header_nritems(leaf);
4474 if (slot != nritems) {
4475 /* shift the items */
4476 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
4477 btrfs_item_nr_offset(slot),
4478 (nritems - slot) * sizeof(struct btrfs_item));
4479 }
4480
4481 btrfs_cpu_key_to_disk(&disk_key, new_key);
4482 btrfs_set_item_key(leaf, &disk_key, slot);
4483
4484 new_item = btrfs_item_nr(slot);
4485
4486 btrfs_set_item_offset(leaf, new_item, orig_offset);
4487 btrfs_set_item_size(leaf, new_item, item_size - split_offset);
4488
4489 btrfs_set_item_offset(leaf, item,
4490 orig_offset + item_size - split_offset);
4491 btrfs_set_item_size(leaf, item, split_offset);
4492
4493 btrfs_set_header_nritems(leaf, nritems + 1);
4494
4495 /* write the data for the start of the original item */
4496 write_extent_buffer(leaf, buf,
4497 btrfs_item_ptr_offset(leaf, path->slots[0]),
4498 split_offset);
4499
4500 /* write the data for the new item */
4501 write_extent_buffer(leaf, buf + split_offset,
4502 btrfs_item_ptr_offset(leaf, slot),
4503 item_size - split_offset);
4504 btrfs_mark_buffer_dirty(leaf);
4505
4506 BUG_ON(btrfs_leaf_free_space(leaf) < 0);
4507 kfree(buf);
4508 return 0;
4509}
4510
4511/*
4512 * This function splits a single item into two items,
4513 * giving 'new_key' to the new item and splitting the
4514 * old one at split_offset (from the start of the item).
4515 *
4516 * The path may be released by this operation. After
4517 * the split, the path is pointing to the old item. The
4518 * new item is going to be in the same node as the old one.
4519 *
4520 * Note, the item being split must be smaller enough to live alone on
4521 * a tree block with room for one extra struct btrfs_item
4522 *
4523 * This allows us to split the item in place, keeping a lock on the
4524 * leaf the entire time.
4525 */
4526int btrfs_split_item(struct btrfs_trans_handle *trans,
4527 struct btrfs_root *root,
4528 struct btrfs_path *path,
4529 const struct btrfs_key *new_key,
4530 unsigned long split_offset)
4531{
4532 int ret;
4533 ret = setup_leaf_for_split(trans, root, path,
4534 sizeof(struct btrfs_item));
4535 if (ret)
4536 return ret;
4537
4538 ret = split_item(path, new_key, split_offset);
4539 return ret;
4540}
4541
4542/*
4543 * This function duplicate a item, giving 'new_key' to the new item.
4544 * It guarantees both items live in the same tree leaf and the new item
4545 * is contiguous with the original item.
4546 *
4547 * This allows us to split file extent in place, keeping a lock on the
4548 * leaf the entire time.
4549 */
4550int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4551 struct btrfs_root *root,
4552 struct btrfs_path *path,
4553 const struct btrfs_key *new_key)
4554{
4555 struct extent_buffer *leaf;
4556 int ret;
4557 u32 item_size;
4558
4559 leaf = path->nodes[0];
4560 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4561 ret = setup_leaf_for_split(trans, root, path,
4562 item_size + sizeof(struct btrfs_item));
4563 if (ret)
4564 return ret;
4565
4566 path->slots[0]++;
4567 setup_items_for_insert(root, path, new_key, &item_size,
4568 item_size, item_size +
4569 sizeof(struct btrfs_item), 1);
4570 leaf = path->nodes[0];
4571 memcpy_extent_buffer(leaf,
4572 btrfs_item_ptr_offset(leaf, path->slots[0]),
4573 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4574 item_size);
4575 return 0;
4576}
4577
4578/*
4579 * make the item pointed to by the path smaller. new_size indicates
4580 * how small to make it, and from_end tells us if we just chop bytes
4581 * off the end of the item or if we shift the item to chop bytes off
4582 * the front.
4583 */
4584void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end)
4585{
4586 int slot;
4587 struct extent_buffer *leaf;
4588 struct btrfs_item *item;
4589 u32 nritems;
4590 unsigned int data_end;
4591 unsigned int old_data_start;
4592 unsigned int old_size;
4593 unsigned int size_diff;
4594 int i;
4595 struct btrfs_map_token token;
4596
4597 leaf = path->nodes[0];
4598 slot = path->slots[0];
4599
4600 old_size = btrfs_item_size_nr(leaf, slot);
4601 if (old_size == new_size)
4602 return;
4603
4604 nritems = btrfs_header_nritems(leaf);
4605 data_end = leaf_data_end(leaf);
4606
4607 old_data_start = btrfs_item_offset_nr(leaf, slot);
4608
4609 size_diff = old_size - new_size;
4610
4611 BUG_ON(slot < 0);
4612 BUG_ON(slot >= nritems);
4613
4614 /*
4615 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4616 */
4617 /* first correct the data pointers */
4618 btrfs_init_map_token(&token, leaf);
4619 for (i = slot; i < nritems; i++) {
4620 u32 ioff;
4621 item = btrfs_item_nr(i);
4622
4623 ioff = btrfs_token_item_offset(leaf, item, &token);
4624 btrfs_set_token_item_offset(leaf, item,
4625 ioff + size_diff, &token);
4626 }
4627
4628 /* shift the data */
4629 if (from_end) {
4630 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4631 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4632 data_end, old_data_start + new_size - data_end);
4633 } else {
4634 struct btrfs_disk_key disk_key;
4635 u64 offset;
4636
4637 btrfs_item_key(leaf, &disk_key, slot);
4638
4639 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4640 unsigned long ptr;
4641 struct btrfs_file_extent_item *fi;
4642
4643 fi = btrfs_item_ptr(leaf, slot,
4644 struct btrfs_file_extent_item);
4645 fi = (struct btrfs_file_extent_item *)(
4646 (unsigned long)fi - size_diff);
4647
4648 if (btrfs_file_extent_type(leaf, fi) ==
4649 BTRFS_FILE_EXTENT_INLINE) {
4650 ptr = btrfs_item_ptr_offset(leaf, slot);
4651 memmove_extent_buffer(leaf, ptr,
4652 (unsigned long)fi,
4653 BTRFS_FILE_EXTENT_INLINE_DATA_START);
4654 }
4655 }
4656
4657 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4658 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4659 data_end, old_data_start - data_end);
4660
4661 offset = btrfs_disk_key_offset(&disk_key);
4662 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4663 btrfs_set_item_key(leaf, &disk_key, slot);
4664 if (slot == 0)
4665 fixup_low_keys(path, &disk_key, 1);
4666 }
4667
4668 item = btrfs_item_nr(slot);
4669 btrfs_set_item_size(leaf, item, new_size);
4670 btrfs_mark_buffer_dirty(leaf);
4671
4672 if (btrfs_leaf_free_space(leaf) < 0) {
4673 btrfs_print_leaf(leaf);
4674 BUG();
4675 }
4676}
4677
4678/*
4679 * make the item pointed to by the path bigger, data_size is the added size.
4680 */
4681void btrfs_extend_item(struct btrfs_path *path, u32 data_size)
4682{
4683 int slot;
4684 struct extent_buffer *leaf;
4685 struct btrfs_item *item;
4686 u32 nritems;
4687 unsigned int data_end;
4688 unsigned int old_data;
4689 unsigned int old_size;
4690 int i;
4691 struct btrfs_map_token token;
4692
4693 leaf = path->nodes[0];
4694
4695 nritems = btrfs_header_nritems(leaf);
4696 data_end = leaf_data_end(leaf);
4697
4698 if (btrfs_leaf_free_space(leaf) < data_size) {
4699 btrfs_print_leaf(leaf);
4700 BUG();
4701 }
4702 slot = path->slots[0];
4703 old_data = btrfs_item_end_nr(leaf, slot);
4704
4705 BUG_ON(slot < 0);
4706 if (slot >= nritems) {
4707 btrfs_print_leaf(leaf);
4708 btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
4709 slot, nritems);
4710 BUG();
4711 }
4712
4713 /*
4714 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4715 */
4716 /* first correct the data pointers */
4717 btrfs_init_map_token(&token, leaf);
4718 for (i = slot; i < nritems; i++) {
4719 u32 ioff;
4720 item = btrfs_item_nr(i);
4721
4722 ioff = btrfs_token_item_offset(leaf, item, &token);
4723 btrfs_set_token_item_offset(leaf, item,
4724 ioff - data_size, &token);
4725 }
4726
4727 /* shift the data */
4728 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4729 data_end - data_size, BTRFS_LEAF_DATA_OFFSET +
4730 data_end, old_data - data_end);
4731
4732 data_end = old_data;
4733 old_size = btrfs_item_size_nr(leaf, slot);
4734 item = btrfs_item_nr(slot);
4735 btrfs_set_item_size(leaf, item, old_size + data_size);
4736 btrfs_mark_buffer_dirty(leaf);
4737
4738 if (btrfs_leaf_free_space(leaf) < 0) {
4739 btrfs_print_leaf(leaf);
4740 BUG();
4741 }
4742}
4743
4744/*
4745 * this is a helper for btrfs_insert_empty_items, the main goal here is
4746 * to save stack depth by doing the bulk of the work in a function
4747 * that doesn't call btrfs_search_slot
4748 */
4749void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
4750 const struct btrfs_key *cpu_key, u32 *data_size,
4751 u32 total_data, u32 total_size, int nr)
4752{
4753 struct btrfs_fs_info *fs_info = root->fs_info;
4754 struct btrfs_item *item;
4755 int i;
4756 u32 nritems;
4757 unsigned int data_end;
4758 struct btrfs_disk_key disk_key;
4759 struct extent_buffer *leaf;
4760 int slot;
4761 struct btrfs_map_token token;
4762
4763 if (path->slots[0] == 0) {
4764 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4765 fixup_low_keys(path, &disk_key, 1);
4766 }
4767 btrfs_unlock_up_safe(path, 1);
4768
4769 leaf = path->nodes[0];
4770 slot = path->slots[0];
4771
4772 nritems = btrfs_header_nritems(leaf);
4773 data_end = leaf_data_end(leaf);
4774
4775 if (btrfs_leaf_free_space(leaf) < total_size) {
4776 btrfs_print_leaf(leaf);
4777 btrfs_crit(fs_info, "not enough freespace need %u have %d",
4778 total_size, btrfs_leaf_free_space(leaf));
4779 BUG();
4780 }
4781
4782 btrfs_init_map_token(&token, leaf);
4783 if (slot != nritems) {
4784 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4785
4786 if (old_data < data_end) {
4787 btrfs_print_leaf(leaf);
4788 btrfs_crit(fs_info, "slot %d old_data %d data_end %d",
4789 slot, old_data, data_end);
4790 BUG();
4791 }
4792 /*
4793 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4794 */
4795 /* first correct the data pointers */
4796 for (i = slot; i < nritems; i++) {
4797 u32 ioff;
4798
4799 item = btrfs_item_nr(i);
4800 ioff = btrfs_token_item_offset(leaf, item, &token);
4801 btrfs_set_token_item_offset(leaf, item,
4802 ioff - total_data, &token);
4803 }
4804 /* shift the items */
4805 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4806 btrfs_item_nr_offset(slot),
4807 (nritems - slot) * sizeof(struct btrfs_item));
4808
4809 /* shift the data */
4810 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4811 data_end - total_data, BTRFS_LEAF_DATA_OFFSET +
4812 data_end, old_data - data_end);
4813 data_end = old_data;
4814 }
4815
4816 /* setup the item for the new data */
4817 for (i = 0; i < nr; i++) {
4818 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4819 btrfs_set_item_key(leaf, &disk_key, slot + i);
4820 item = btrfs_item_nr(slot + i);
4821 btrfs_set_token_item_offset(leaf, item,
4822 data_end - data_size[i], &token);
4823 data_end -= data_size[i];
4824 btrfs_set_token_item_size(leaf, item, data_size[i], &token);
4825 }
4826
4827 btrfs_set_header_nritems(leaf, nritems + nr);
4828 btrfs_mark_buffer_dirty(leaf);
4829
4830 if (btrfs_leaf_free_space(leaf) < 0) {
4831 btrfs_print_leaf(leaf);
4832 BUG();
4833 }
4834}
4835
4836/*
4837 * Given a key and some data, insert items into the tree.
4838 * This does all the path init required, making room in the tree if needed.
4839 */
4840int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4841 struct btrfs_root *root,
4842 struct btrfs_path *path,
4843 const struct btrfs_key *cpu_key, u32 *data_size,
4844 int nr)
4845{
4846 int ret = 0;
4847 int slot;
4848 int i;
4849 u32 total_size = 0;
4850 u32 total_data = 0;
4851
4852 for (i = 0; i < nr; i++)
4853 total_data += data_size[i];
4854
4855 total_size = total_data + (nr * sizeof(struct btrfs_item));
4856 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4857 if (ret == 0)
4858 return -EEXIST;
4859 if (ret < 0)
4860 return ret;
4861
4862 slot = path->slots[0];
4863 BUG_ON(slot < 0);
4864
4865 setup_items_for_insert(root, path, cpu_key, data_size,
4866 total_data, total_size, nr);
4867 return 0;
4868}
4869
4870/*
4871 * Given a key and some data, insert an item into the tree.
4872 * This does all the path init required, making room in the tree if needed.
4873 */
4874int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4875 const struct btrfs_key *cpu_key, void *data,
4876 u32 data_size)
4877{
4878 int ret = 0;
4879 struct btrfs_path *path;
4880 struct extent_buffer *leaf;
4881 unsigned long ptr;
4882
4883 path = btrfs_alloc_path();
4884 if (!path)
4885 return -ENOMEM;
4886 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4887 if (!ret) {
4888 leaf = path->nodes[0];
4889 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4890 write_extent_buffer(leaf, data, ptr, data_size);
4891 btrfs_mark_buffer_dirty(leaf);
4892 }
4893 btrfs_free_path(path);
4894 return ret;
4895}
4896
4897/*
4898 * delete the pointer from a given node.
4899 *
4900 * the tree should have been previously balanced so the deletion does not
4901 * empty a node.
4902 */
4903static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
4904 int level, int slot)
4905{
4906 struct extent_buffer *parent = path->nodes[level];
4907 u32 nritems;
4908 int ret;
4909
4910 nritems = btrfs_header_nritems(parent);
4911 if (slot != nritems - 1) {
4912 if (level) {
4913 ret = tree_mod_log_insert_move(parent, slot, slot + 1,
4914 nritems - slot - 1);
4915 BUG_ON(ret < 0);
4916 }
4917 memmove_extent_buffer(parent,
4918 btrfs_node_key_ptr_offset(slot),
4919 btrfs_node_key_ptr_offset(slot + 1),
4920 sizeof(struct btrfs_key_ptr) *
4921 (nritems - slot - 1));
4922 } else if (level) {
4923 ret = tree_mod_log_insert_key(parent, slot, MOD_LOG_KEY_REMOVE,
4924 GFP_NOFS);
4925 BUG_ON(ret < 0);
4926 }
4927
4928 nritems--;
4929 btrfs_set_header_nritems(parent, nritems);
4930 if (nritems == 0 && parent == root->node) {
4931 BUG_ON(btrfs_header_level(root->node) != 1);
4932 /* just turn the root into a leaf and break */
4933 btrfs_set_header_level(root->node, 0);
4934 } else if (slot == 0) {
4935 struct btrfs_disk_key disk_key;
4936
4937 btrfs_node_key(parent, &disk_key, 0);
4938 fixup_low_keys(path, &disk_key, level + 1);
4939 }
4940 btrfs_mark_buffer_dirty(parent);
4941}
4942
4943/*
4944 * a helper function to delete the leaf pointed to by path->slots[1] and
4945 * path->nodes[1].
4946 *
4947 * This deletes the pointer in path->nodes[1] and frees the leaf
4948 * block extent. zero is returned if it all worked out, < 0 otherwise.
4949 *
4950 * The path must have already been setup for deleting the leaf, including
4951 * all the proper balancing. path->nodes[1] must be locked.
4952 */
4953static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4954 struct btrfs_root *root,
4955 struct btrfs_path *path,
4956 struct extent_buffer *leaf)
4957{
4958 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4959 del_ptr(root, path, 1, path->slots[1]);
4960
4961 /*
4962 * btrfs_free_extent is expensive, we want to make sure we
4963 * aren't holding any locks when we call it
4964 */
4965 btrfs_unlock_up_safe(path, 0);
4966
4967 root_sub_used(root, leaf->len);
4968
4969 extent_buffer_get(leaf);
4970 btrfs_free_tree_block(trans, root, leaf, 0, 1);
4971 free_extent_buffer_stale(leaf);
4972}
4973/*
4974 * delete the item at the leaf level in path. If that empties
4975 * the leaf, remove it from the tree
4976 */
4977int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4978 struct btrfs_path *path, int slot, int nr)
4979{
4980 struct btrfs_fs_info *fs_info = root->fs_info;
4981 struct extent_buffer *leaf;
4982 struct btrfs_item *item;
4983 u32 last_off;
4984 u32 dsize = 0;
4985 int ret = 0;
4986 int wret;
4987 int i;
4988 u32 nritems;
4989
4990 leaf = path->nodes[0];
4991 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4992
4993 for (i = 0; i < nr; i++)
4994 dsize += btrfs_item_size_nr(leaf, slot + i);
4995
4996 nritems = btrfs_header_nritems(leaf);
4997
4998 if (slot + nr != nritems) {
4999 int data_end = leaf_data_end(leaf);
5000 struct btrfs_map_token token;
5001
5002 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
5003 data_end + dsize,
5004 BTRFS_LEAF_DATA_OFFSET + data_end,
5005 last_off - data_end);
5006
5007 btrfs_init_map_token(&token, leaf);
5008 for (i = slot + nr; i < nritems; i++) {
5009 u32 ioff;
5010
5011 item = btrfs_item_nr(i);
5012 ioff = btrfs_token_item_offset(leaf, item, &token);
5013 btrfs_set_token_item_offset(leaf, item,
5014 ioff + dsize, &token);
5015 }
5016
5017 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
5018 btrfs_item_nr_offset(slot + nr),
5019 sizeof(struct btrfs_item) *
5020 (nritems - slot - nr));
5021 }
5022 btrfs_set_header_nritems(leaf, nritems - nr);
5023 nritems -= nr;
5024
5025 /* delete the leaf if we've emptied it */
5026 if (nritems == 0) {
5027 if (leaf == root->node) {
5028 btrfs_set_header_level(leaf, 0);
5029 } else {
5030 btrfs_set_path_blocking(path);
5031 btrfs_clean_tree_block(leaf);
5032 btrfs_del_leaf(trans, root, path, leaf);
5033 }
5034 } else {
5035 int used = leaf_space_used(leaf, 0, nritems);
5036 if (slot == 0) {
5037 struct btrfs_disk_key disk_key;
5038
5039 btrfs_item_key(leaf, &disk_key, 0);
5040 fixup_low_keys(path, &disk_key, 1);
5041 }
5042
5043 /* delete the leaf if it is mostly empty */
5044 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
5045 /* push_leaf_left fixes the path.
5046 * make sure the path still points to our leaf
5047 * for possible call to del_ptr below
5048 */
5049 slot = path->slots[1];
5050 extent_buffer_get(leaf);
5051
5052 btrfs_set_path_blocking(path);
5053 wret = push_leaf_left(trans, root, path, 1, 1,
5054 1, (u32)-1);
5055 if (wret < 0 && wret != -ENOSPC)
5056 ret = wret;
5057
5058 if (path->nodes[0] == leaf &&
5059 btrfs_header_nritems(leaf)) {
5060 wret = push_leaf_right(trans, root, path, 1,
5061 1, 1, 0);
5062 if (wret < 0 && wret != -ENOSPC)
5063 ret = wret;
5064 }
5065
5066 if (btrfs_header_nritems(leaf) == 0) {
5067 path->slots[1] = slot;
5068 btrfs_del_leaf(trans, root, path, leaf);
5069 free_extent_buffer(leaf);
5070 ret = 0;
5071 } else {
5072 /* if we're still in the path, make sure
5073 * we're dirty. Otherwise, one of the
5074 * push_leaf functions must have already
5075 * dirtied this buffer
5076 */
5077 if (path->nodes[0] == leaf)
5078 btrfs_mark_buffer_dirty(leaf);
5079 free_extent_buffer(leaf);
5080 }
5081 } else {
5082 btrfs_mark_buffer_dirty(leaf);
5083 }
5084 }
5085 return ret;
5086}
5087
5088/*
5089 * search the tree again to find a leaf with lesser keys
5090 * returns 0 if it found something or 1 if there are no lesser leaves.
5091 * returns < 0 on io errors.
5092 *
5093 * This may release the path, and so you may lose any locks held at the
5094 * time you call it.
5095 */
5096int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
5097{
5098 struct btrfs_key key;
5099 struct btrfs_disk_key found_key;
5100 int ret;
5101
5102 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
5103
5104 if (key.offset > 0) {
5105 key.offset--;
5106 } else if (key.type > 0) {
5107 key.type--;
5108 key.offset = (u64)-1;
5109 } else if (key.objectid > 0) {
5110 key.objectid--;
5111 key.type = (u8)-1;
5112 key.offset = (u64)-1;
5113 } else {
5114 return 1;
5115 }
5116
5117 btrfs_release_path(path);
5118 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5119 if (ret < 0)
5120 return ret;
5121 btrfs_item_key(path->nodes[0], &found_key, 0);
5122 ret = comp_keys(&found_key, &key);
5123 /*
5124 * We might have had an item with the previous key in the tree right
5125 * before we released our path. And after we released our path, that
5126 * item might have been pushed to the first slot (0) of the leaf we
5127 * were holding due to a tree balance. Alternatively, an item with the
5128 * previous key can exist as the only element of a leaf (big fat item).
5129 * Therefore account for these 2 cases, so that our callers (like
5130 * btrfs_previous_item) don't miss an existing item with a key matching
5131 * the previous key we computed above.
5132 */
5133 if (ret <= 0)
5134 return 0;
5135 return 1;
5136}
5137
5138/*
5139 * A helper function to walk down the tree starting at min_key, and looking
5140 * for nodes or leaves that are have a minimum transaction id.
5141 * This is used by the btree defrag code, and tree logging
5142 *
5143 * This does not cow, but it does stuff the starting key it finds back
5144 * into min_key, so you can call btrfs_search_slot with cow=1 on the
5145 * key and get a writable path.
5146 *
5147 * This honors path->lowest_level to prevent descent past a given level
5148 * of the tree.
5149 *
5150 * min_trans indicates the oldest transaction that you are interested
5151 * in walking through. Any nodes or leaves older than min_trans are
5152 * skipped over (without reading them).
5153 *
5154 * returns zero if something useful was found, < 0 on error and 1 if there
5155 * was nothing in the tree that matched the search criteria.
5156 */
5157int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
5158 struct btrfs_path *path,
5159 u64 min_trans)
5160{
5161 struct extent_buffer *cur;
5162 struct btrfs_key found_key;
5163 int slot;
5164 int sret;
5165 u32 nritems;
5166 int level;
5167 int ret = 1;
5168 int keep_locks = path->keep_locks;
5169
5170 path->keep_locks = 1;
5171again:
5172 cur = btrfs_read_lock_root_node(root);
5173 level = btrfs_header_level(cur);
5174 WARN_ON(path->nodes[level]);
5175 path->nodes[level] = cur;
5176 path->locks[level] = BTRFS_READ_LOCK;
5177
5178 if (btrfs_header_generation(cur) < min_trans) {
5179 ret = 1;
5180 goto out;
5181 }
5182 while (1) {
5183 nritems = btrfs_header_nritems(cur);
5184 level = btrfs_header_level(cur);
5185 sret = btrfs_bin_search(cur, min_key, level, &slot);
5186 if (sret < 0) {
5187 ret = sret;
5188 goto out;
5189 }
5190
5191 /* at the lowest level, we're done, setup the path and exit */
5192 if (level == path->lowest_level) {
5193 if (slot >= nritems)
5194 goto find_next_key;
5195 ret = 0;
5196 path->slots[level] = slot;
5197 btrfs_item_key_to_cpu(cur, &found_key, slot);
5198 goto out;
5199 }
5200 if (sret && slot > 0)
5201 slot--;
5202 /*
5203 * check this node pointer against the min_trans parameters.
5204 * If it is too old, old, skip to the next one.
5205 */
5206 while (slot < nritems) {
5207 u64 gen;
5208
5209 gen = btrfs_node_ptr_generation(cur, slot);
5210 if (gen < min_trans) {
5211 slot++;
5212 continue;
5213 }
5214 break;
5215 }
5216find_next_key:
5217 /*
5218 * we didn't find a candidate key in this node, walk forward
5219 * and find another one
5220 */
5221 if (slot >= nritems) {
5222 path->slots[level] = slot;
5223 btrfs_set_path_blocking(path);
5224 sret = btrfs_find_next_key(root, path, min_key, level,
5225 min_trans);
5226 if (sret == 0) {
5227 btrfs_release_path(path);
5228 goto again;
5229 } else {
5230 goto out;
5231 }
5232 }
5233 /* save our key for returning back */
5234 btrfs_node_key_to_cpu(cur, &found_key, slot);
5235 path->slots[level] = slot;
5236 if (level == path->lowest_level) {
5237 ret = 0;
5238 goto out;
5239 }
5240 btrfs_set_path_blocking(path);
5241 cur = btrfs_read_node_slot(cur, slot);
5242 if (IS_ERR(cur)) {
5243 ret = PTR_ERR(cur);
5244 goto out;
5245 }
5246
5247 btrfs_tree_read_lock(cur);
5248
5249 path->locks[level - 1] = BTRFS_READ_LOCK;
5250 path->nodes[level - 1] = cur;
5251 unlock_up(path, level, 1, 0, NULL);
5252 }
5253out:
5254 path->keep_locks = keep_locks;
5255 if (ret == 0) {
5256 btrfs_unlock_up_safe(path, path->lowest_level + 1);
5257 btrfs_set_path_blocking(path);
5258 memcpy(min_key, &found_key, sizeof(found_key));
5259 }
5260 return ret;
5261}
5262
5263/*
5264 * this is similar to btrfs_next_leaf, but does not try to preserve
5265 * and fixup the path. It looks for and returns the next key in the
5266 * tree based on the current path and the min_trans parameters.
5267 *
5268 * 0 is returned if another key is found, < 0 if there are any errors
5269 * and 1 is returned if there are no higher keys in the tree
5270 *
5271 * path->keep_locks should be set to 1 on the search made before
5272 * calling this function.
5273 */
5274int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
5275 struct btrfs_key *key, int level, u64 min_trans)
5276{
5277 int slot;
5278 struct extent_buffer *c;
5279
5280 WARN_ON(!path->keep_locks && !path->skip_locking);
5281 while (level < BTRFS_MAX_LEVEL) {
5282 if (!path->nodes[level])
5283 return 1;
5284
5285 slot = path->slots[level] + 1;
5286 c = path->nodes[level];
5287next:
5288 if (slot >= btrfs_header_nritems(c)) {
5289 int ret;
5290 int orig_lowest;
5291 struct btrfs_key cur_key;
5292 if (level + 1 >= BTRFS_MAX_LEVEL ||
5293 !path->nodes[level + 1])
5294 return 1;
5295
5296 if (path->locks[level + 1] || path->skip_locking) {
5297 level++;
5298 continue;
5299 }
5300
5301 slot = btrfs_header_nritems(c) - 1;
5302 if (level == 0)
5303 btrfs_item_key_to_cpu(c, &cur_key, slot);
5304 else
5305 btrfs_node_key_to_cpu(c, &cur_key, slot);
5306
5307 orig_lowest = path->lowest_level;
5308 btrfs_release_path(path);
5309 path->lowest_level = level;
5310 ret = btrfs_search_slot(NULL, root, &cur_key, path,
5311 0, 0);
5312 path->lowest_level = orig_lowest;
5313 if (ret < 0)
5314 return ret;
5315
5316 c = path->nodes[level];
5317 slot = path->slots[level];
5318 if (ret == 0)
5319 slot++;
5320 goto next;
5321 }
5322
5323 if (level == 0)
5324 btrfs_item_key_to_cpu(c, key, slot);
5325 else {
5326 u64 gen = btrfs_node_ptr_generation(c, slot);
5327
5328 if (gen < min_trans) {
5329 slot++;
5330 goto next;
5331 }
5332 btrfs_node_key_to_cpu(c, key, slot);
5333 }
5334 return 0;
5335 }
5336 return 1;
5337}
5338
5339/*
5340 * search the tree again to find a leaf with greater keys
5341 * returns 0 if it found something or 1 if there are no greater leaves.
5342 * returns < 0 on io errors.
5343 */
5344int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
5345{
5346 return btrfs_next_old_leaf(root, path, 0);
5347}
5348
5349int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
5350 u64 time_seq)
5351{
5352 int slot;
5353 int level;
5354 struct extent_buffer *c;
5355 struct extent_buffer *next;
5356 struct btrfs_key key;
5357 u32 nritems;
5358 int ret;
5359 int old_spinning = path->leave_spinning;
5360 int next_rw_lock = 0;
5361
5362 nritems = btrfs_header_nritems(path->nodes[0]);
5363 if (nritems == 0)
5364 return 1;
5365
5366 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5367again:
5368 level = 1;
5369 next = NULL;
5370 next_rw_lock = 0;
5371 btrfs_release_path(path);
5372
5373 path->keep_locks = 1;
5374 path->leave_spinning = 1;
5375
5376 if (time_seq)
5377 ret = btrfs_search_old_slot(root, &key, path, time_seq);
5378 else
5379 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5380 path->keep_locks = 0;
5381
5382 if (ret < 0)
5383 return ret;
5384
5385 nritems = btrfs_header_nritems(path->nodes[0]);
5386 /*
5387 * by releasing the path above we dropped all our locks. A balance
5388 * could have added more items next to the key that used to be
5389 * at the very end of the block. So, check again here and
5390 * advance the path if there are now more items available.
5391 */
5392 if (nritems > 0 && path->slots[0] < nritems - 1) {
5393 if (ret == 0)
5394 path->slots[0]++;
5395 ret = 0;
5396 goto done;
5397 }
5398 /*
5399 * So the above check misses one case:
5400 * - after releasing the path above, someone has removed the item that
5401 * used to be at the very end of the block, and balance between leafs
5402 * gets another one with bigger key.offset to replace it.
5403 *
5404 * This one should be returned as well, or we can get leaf corruption
5405 * later(esp. in __btrfs_drop_extents()).
5406 *
5407 * And a bit more explanation about this check,
5408 * with ret > 0, the key isn't found, the path points to the slot
5409 * where it should be inserted, so the path->slots[0] item must be the
5410 * bigger one.
5411 */
5412 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
5413 ret = 0;
5414 goto done;
5415 }
5416
5417 while (level < BTRFS_MAX_LEVEL) {
5418 if (!path->nodes[level]) {
5419 ret = 1;
5420 goto done;
5421 }
5422
5423 slot = path->slots[level] + 1;
5424 c = path->nodes[level];
5425 if (slot >= btrfs_header_nritems(c)) {
5426 level++;
5427 if (level == BTRFS_MAX_LEVEL) {
5428 ret = 1;
5429 goto done;
5430 }
5431 continue;
5432 }
5433
5434 if (next) {
5435 btrfs_tree_unlock_rw(next, next_rw_lock);
5436 free_extent_buffer(next);
5437 }
5438
5439 next = c;
5440 next_rw_lock = path->locks[level];
5441 ret = read_block_for_search(root, path, &next, level,
5442 slot, &key);
5443 if (ret == -EAGAIN)
5444 goto again;
5445
5446 if (ret < 0) {
5447 btrfs_release_path(path);
5448 goto done;
5449 }
5450
5451 if (!path->skip_locking) {
5452 ret = btrfs_try_tree_read_lock(next);
5453 if (!ret && time_seq) {
5454 /*
5455 * If we don't get the lock, we may be racing
5456 * with push_leaf_left, holding that lock while
5457 * itself waiting for the leaf we've currently
5458 * locked. To solve this situation, we give up
5459 * on our lock and cycle.
5460 */
5461 free_extent_buffer(next);
5462 btrfs_release_path(path);
5463 cond_resched();
5464 goto again;
5465 }
5466 if (!ret) {
5467 btrfs_set_path_blocking(path);
5468 btrfs_tree_read_lock(next);
5469 }
5470 next_rw_lock = BTRFS_READ_LOCK;
5471 }
5472 break;
5473 }
5474 path->slots[level] = slot;
5475 while (1) {
5476 level--;
5477 c = path->nodes[level];
5478 if (path->locks[level])
5479 btrfs_tree_unlock_rw(c, path->locks[level]);
5480
5481 free_extent_buffer(c);
5482 path->nodes[level] = next;
5483 path->slots[level] = 0;
5484 if (!path->skip_locking)
5485 path->locks[level] = next_rw_lock;
5486 if (!level)
5487 break;
5488
5489 ret = read_block_for_search(root, path, &next, level,
5490 0, &key);
5491 if (ret == -EAGAIN)
5492 goto again;
5493
5494 if (ret < 0) {
5495 btrfs_release_path(path);
5496 goto done;
5497 }
5498
5499 if (!path->skip_locking) {
5500 ret = btrfs_try_tree_read_lock(next);
5501 if (!ret) {
5502 btrfs_set_path_blocking(path);
5503 btrfs_tree_read_lock(next);
5504 }
5505 next_rw_lock = BTRFS_READ_LOCK;
5506 }
5507 }
5508 ret = 0;
5509done:
5510 unlock_up(path, 0, 1, 0, NULL);
5511 path->leave_spinning = old_spinning;
5512 if (!old_spinning)
5513 btrfs_set_path_blocking(path);
5514
5515 return ret;
5516}
5517
5518/*
5519 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5520 * searching until it gets past min_objectid or finds an item of 'type'
5521 *
5522 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5523 */
5524int btrfs_previous_item(struct btrfs_root *root,
5525 struct btrfs_path *path, u64 min_objectid,
5526 int type)
5527{
5528 struct btrfs_key found_key;
5529 struct extent_buffer *leaf;
5530 u32 nritems;
5531 int ret;
5532
5533 while (1) {
5534 if (path->slots[0] == 0) {
5535 btrfs_set_path_blocking(path);
5536 ret = btrfs_prev_leaf(root, path);
5537 if (ret != 0)
5538 return ret;
5539 } else {
5540 path->slots[0]--;
5541 }
5542 leaf = path->nodes[0];
5543 nritems = btrfs_header_nritems(leaf);
5544 if (nritems == 0)
5545 return 1;
5546 if (path->slots[0] == nritems)
5547 path->slots[0]--;
5548
5549 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5550 if (found_key.objectid < min_objectid)
5551 break;
5552 if (found_key.type == type)
5553 return 0;
5554 if (found_key.objectid == min_objectid &&
5555 found_key.type < type)
5556 break;
5557 }
5558 return 1;
5559}
5560
5561/*
5562 * search in extent tree to find a previous Metadata/Data extent item with
5563 * min objecitd.
5564 *
5565 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5566 */
5567int btrfs_previous_extent_item(struct btrfs_root *root,
5568 struct btrfs_path *path, u64 min_objectid)
5569{
5570 struct btrfs_key found_key;
5571 struct extent_buffer *leaf;
5572 u32 nritems;
5573 int ret;
5574
5575 while (1) {
5576 if (path->slots[0] == 0) {
5577 btrfs_set_path_blocking(path);
5578 ret = btrfs_prev_leaf(root, path);
5579 if (ret != 0)
5580 return ret;
5581 } else {
5582 path->slots[0]--;
5583 }
5584 leaf = path->nodes[0];
5585 nritems = btrfs_header_nritems(leaf);
5586 if (nritems == 0)
5587 return 1;
5588 if (path->slots[0] == nritems)
5589 path->slots[0]--;
5590
5591 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5592 if (found_key.objectid < min_objectid)
5593 break;
5594 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5595 found_key.type == BTRFS_METADATA_ITEM_KEY)
5596 return 0;
5597 if (found_key.objectid == min_objectid &&
5598 found_key.type < BTRFS_EXTENT_ITEM_KEY)
5599 break;
5600 }
5601 return 1;
5602}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007,2008 Oracle. All rights reserved.
4 */
5
6#include <linux/sched.h>
7#include <linux/slab.h>
8#include <linux/rbtree.h>
9#include <linux/mm.h>
10#include "ctree.h"
11#include "disk-io.h"
12#include "transaction.h"
13#include "print-tree.h"
14#include "locking.h"
15#include "volumes.h"
16#include "qgroup.h"
17#include "tree-mod-log.h"
18
19static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
20 *root, struct btrfs_path *path, int level);
21static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
22 const struct btrfs_key *ins_key, struct btrfs_path *path,
23 int data_size, int extend);
24static int push_node_left(struct btrfs_trans_handle *trans,
25 struct extent_buffer *dst,
26 struct extent_buffer *src, int empty);
27static int balance_node_right(struct btrfs_trans_handle *trans,
28 struct extent_buffer *dst_buf,
29 struct extent_buffer *src_buf);
30static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
31 int level, int slot);
32
33static const struct btrfs_csums {
34 u16 size;
35 const char name[10];
36 const char driver[12];
37} btrfs_csums[] = {
38 [BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
39 [BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
40 [BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
41 [BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
42 .driver = "blake2b-256" },
43};
44
45int btrfs_super_csum_size(const struct btrfs_super_block *s)
46{
47 u16 t = btrfs_super_csum_type(s);
48 /*
49 * csum type is validated at mount time
50 */
51 return btrfs_csums[t].size;
52}
53
54const char *btrfs_super_csum_name(u16 csum_type)
55{
56 /* csum type is validated at mount time */
57 return btrfs_csums[csum_type].name;
58}
59
60/*
61 * Return driver name if defined, otherwise the name that's also a valid driver
62 * name
63 */
64const char *btrfs_super_csum_driver(u16 csum_type)
65{
66 /* csum type is validated at mount time */
67 return btrfs_csums[csum_type].driver[0] ?
68 btrfs_csums[csum_type].driver :
69 btrfs_csums[csum_type].name;
70}
71
72size_t __attribute_const__ btrfs_get_num_csums(void)
73{
74 return ARRAY_SIZE(btrfs_csums);
75}
76
77struct btrfs_path *btrfs_alloc_path(void)
78{
79 return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
80}
81
82/* this also releases the path */
83void btrfs_free_path(struct btrfs_path *p)
84{
85 if (!p)
86 return;
87 btrfs_release_path(p);
88 kmem_cache_free(btrfs_path_cachep, p);
89}
90
91/*
92 * path release drops references on the extent buffers in the path
93 * and it drops any locks held by this path
94 *
95 * It is safe to call this on paths that no locks or extent buffers held.
96 */
97noinline void btrfs_release_path(struct btrfs_path *p)
98{
99 int i;
100
101 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
102 p->slots[i] = 0;
103 if (!p->nodes[i])
104 continue;
105 if (p->locks[i]) {
106 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
107 p->locks[i] = 0;
108 }
109 free_extent_buffer(p->nodes[i]);
110 p->nodes[i] = NULL;
111 }
112}
113
114/*
115 * safely gets a reference on the root node of a tree. A lock
116 * is not taken, so a concurrent writer may put a different node
117 * at the root of the tree. See btrfs_lock_root_node for the
118 * looping required.
119 *
120 * The extent buffer returned by this has a reference taken, so
121 * it won't disappear. It may stop being the root of the tree
122 * at any time because there are no locks held.
123 */
124struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
125{
126 struct extent_buffer *eb;
127
128 while (1) {
129 rcu_read_lock();
130 eb = rcu_dereference(root->node);
131
132 /*
133 * RCU really hurts here, we could free up the root node because
134 * it was COWed but we may not get the new root node yet so do
135 * the inc_not_zero dance and if it doesn't work then
136 * synchronize_rcu and try again.
137 */
138 if (atomic_inc_not_zero(&eb->refs)) {
139 rcu_read_unlock();
140 break;
141 }
142 rcu_read_unlock();
143 synchronize_rcu();
144 }
145 return eb;
146}
147
148/*
149 * Cowonly root (not-shareable trees, everything not subvolume or reloc roots),
150 * just get put onto a simple dirty list. Transaction walks this list to make
151 * sure they get properly updated on disk.
152 */
153static void add_root_to_dirty_list(struct btrfs_root *root)
154{
155 struct btrfs_fs_info *fs_info = root->fs_info;
156
157 if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
158 !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
159 return;
160
161 spin_lock(&fs_info->trans_lock);
162 if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
163 /* Want the extent tree to be the last on the list */
164 if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID)
165 list_move_tail(&root->dirty_list,
166 &fs_info->dirty_cowonly_roots);
167 else
168 list_move(&root->dirty_list,
169 &fs_info->dirty_cowonly_roots);
170 }
171 spin_unlock(&fs_info->trans_lock);
172}
173
174/*
175 * used by snapshot creation to make a copy of a root for a tree with
176 * a given objectid. The buffer with the new root node is returned in
177 * cow_ret, and this func returns zero on success or a negative error code.
178 */
179int btrfs_copy_root(struct btrfs_trans_handle *trans,
180 struct btrfs_root *root,
181 struct extent_buffer *buf,
182 struct extent_buffer **cow_ret, u64 new_root_objectid)
183{
184 struct btrfs_fs_info *fs_info = root->fs_info;
185 struct extent_buffer *cow;
186 int ret = 0;
187 int level;
188 struct btrfs_disk_key disk_key;
189
190 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
191 trans->transid != fs_info->running_transaction->transid);
192 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
193 trans->transid != root->last_trans);
194
195 level = btrfs_header_level(buf);
196 if (level == 0)
197 btrfs_item_key(buf, &disk_key, 0);
198 else
199 btrfs_node_key(buf, &disk_key, 0);
200
201 cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
202 &disk_key, level, buf->start, 0,
203 BTRFS_NESTING_NEW_ROOT);
204 if (IS_ERR(cow))
205 return PTR_ERR(cow);
206
207 copy_extent_buffer_full(cow, buf);
208 btrfs_set_header_bytenr(cow, cow->start);
209 btrfs_set_header_generation(cow, trans->transid);
210 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
211 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
212 BTRFS_HEADER_FLAG_RELOC);
213 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
214 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
215 else
216 btrfs_set_header_owner(cow, new_root_objectid);
217
218 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
219
220 WARN_ON(btrfs_header_generation(buf) > trans->transid);
221 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
222 ret = btrfs_inc_ref(trans, root, cow, 1);
223 else
224 ret = btrfs_inc_ref(trans, root, cow, 0);
225 if (ret) {
226 btrfs_tree_unlock(cow);
227 free_extent_buffer(cow);
228 btrfs_abort_transaction(trans, ret);
229 return ret;
230 }
231
232 btrfs_mark_buffer_dirty(cow);
233 *cow_ret = cow;
234 return 0;
235}
236
237/*
238 * check if the tree block can be shared by multiple trees
239 */
240int btrfs_block_can_be_shared(struct btrfs_root *root,
241 struct extent_buffer *buf)
242{
243 /*
244 * Tree blocks not in shareable trees and tree roots are never shared.
245 * If a block was allocated after the last snapshot and the block was
246 * not allocated by tree relocation, we know the block is not shared.
247 */
248 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
249 buf != root->node && buf != root->commit_root &&
250 (btrfs_header_generation(buf) <=
251 btrfs_root_last_snapshot(&root->root_item) ||
252 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
253 return 1;
254
255 return 0;
256}
257
258static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
259 struct btrfs_root *root,
260 struct extent_buffer *buf,
261 struct extent_buffer *cow,
262 int *last_ref)
263{
264 struct btrfs_fs_info *fs_info = root->fs_info;
265 u64 refs;
266 u64 owner;
267 u64 flags;
268 u64 new_flags = 0;
269 int ret;
270
271 /*
272 * Backrefs update rules:
273 *
274 * Always use full backrefs for extent pointers in tree block
275 * allocated by tree relocation.
276 *
277 * If a shared tree block is no longer referenced by its owner
278 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
279 * use full backrefs for extent pointers in tree block.
280 *
281 * If a tree block is been relocating
282 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
283 * use full backrefs for extent pointers in tree block.
284 * The reason for this is some operations (such as drop tree)
285 * are only allowed for blocks use full backrefs.
286 */
287
288 if (btrfs_block_can_be_shared(root, buf)) {
289 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
290 btrfs_header_level(buf), 1,
291 &refs, &flags);
292 if (ret)
293 return ret;
294 if (refs == 0) {
295 ret = -EROFS;
296 btrfs_handle_fs_error(fs_info, ret, NULL);
297 return ret;
298 }
299 } else {
300 refs = 1;
301 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
302 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
303 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
304 else
305 flags = 0;
306 }
307
308 owner = btrfs_header_owner(buf);
309 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
310 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
311
312 if (refs > 1) {
313 if ((owner == root->root_key.objectid ||
314 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
315 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
316 ret = btrfs_inc_ref(trans, root, buf, 1);
317 if (ret)
318 return ret;
319
320 if (root->root_key.objectid ==
321 BTRFS_TREE_RELOC_OBJECTID) {
322 ret = btrfs_dec_ref(trans, root, buf, 0);
323 if (ret)
324 return ret;
325 ret = btrfs_inc_ref(trans, root, cow, 1);
326 if (ret)
327 return ret;
328 }
329 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
330 } else {
331
332 if (root->root_key.objectid ==
333 BTRFS_TREE_RELOC_OBJECTID)
334 ret = btrfs_inc_ref(trans, root, cow, 1);
335 else
336 ret = btrfs_inc_ref(trans, root, cow, 0);
337 if (ret)
338 return ret;
339 }
340 if (new_flags != 0) {
341 int level = btrfs_header_level(buf);
342
343 ret = btrfs_set_disk_extent_flags(trans, buf,
344 new_flags, level, 0);
345 if (ret)
346 return ret;
347 }
348 } else {
349 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
350 if (root->root_key.objectid ==
351 BTRFS_TREE_RELOC_OBJECTID)
352 ret = btrfs_inc_ref(trans, root, cow, 1);
353 else
354 ret = btrfs_inc_ref(trans, root, cow, 0);
355 if (ret)
356 return ret;
357 ret = btrfs_dec_ref(trans, root, buf, 1);
358 if (ret)
359 return ret;
360 }
361 btrfs_clean_tree_block(buf);
362 *last_ref = 1;
363 }
364 return 0;
365}
366
367/*
368 * does the dirty work in cow of a single block. The parent block (if
369 * supplied) is updated to point to the new cow copy. The new buffer is marked
370 * dirty and returned locked. If you modify the block it needs to be marked
371 * dirty again.
372 *
373 * search_start -- an allocation hint for the new block
374 *
375 * empty_size -- a hint that you plan on doing more cow. This is the size in
376 * bytes the allocator should try to find free next to the block it returns.
377 * This is just a hint and may be ignored by the allocator.
378 */
379static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
380 struct btrfs_root *root,
381 struct extent_buffer *buf,
382 struct extent_buffer *parent, int parent_slot,
383 struct extent_buffer **cow_ret,
384 u64 search_start, u64 empty_size,
385 enum btrfs_lock_nesting nest)
386{
387 struct btrfs_fs_info *fs_info = root->fs_info;
388 struct btrfs_disk_key disk_key;
389 struct extent_buffer *cow;
390 int level, ret;
391 int last_ref = 0;
392 int unlock_orig = 0;
393 u64 parent_start = 0;
394
395 if (*cow_ret == buf)
396 unlock_orig = 1;
397
398 btrfs_assert_tree_locked(buf);
399
400 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
401 trans->transid != fs_info->running_transaction->transid);
402 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
403 trans->transid != root->last_trans);
404
405 level = btrfs_header_level(buf);
406
407 if (level == 0)
408 btrfs_item_key(buf, &disk_key, 0);
409 else
410 btrfs_node_key(buf, &disk_key, 0);
411
412 if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
413 parent_start = parent->start;
414
415 cow = btrfs_alloc_tree_block(trans, root, parent_start,
416 root->root_key.objectid, &disk_key, level,
417 search_start, empty_size, nest);
418 if (IS_ERR(cow))
419 return PTR_ERR(cow);
420
421 /* cow is set to blocking by btrfs_init_new_buffer */
422
423 copy_extent_buffer_full(cow, buf);
424 btrfs_set_header_bytenr(cow, cow->start);
425 btrfs_set_header_generation(cow, trans->transid);
426 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
427 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
428 BTRFS_HEADER_FLAG_RELOC);
429 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
430 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
431 else
432 btrfs_set_header_owner(cow, root->root_key.objectid);
433
434 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
435
436 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
437 if (ret) {
438 btrfs_tree_unlock(cow);
439 free_extent_buffer(cow);
440 btrfs_abort_transaction(trans, ret);
441 return ret;
442 }
443
444 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
445 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
446 if (ret) {
447 btrfs_tree_unlock(cow);
448 free_extent_buffer(cow);
449 btrfs_abort_transaction(trans, ret);
450 return ret;
451 }
452 }
453
454 if (buf == root->node) {
455 WARN_ON(parent && parent != buf);
456 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
457 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
458 parent_start = buf->start;
459
460 atomic_inc(&cow->refs);
461 ret = btrfs_tree_mod_log_insert_root(root->node, cow, true);
462 BUG_ON(ret < 0);
463 rcu_assign_pointer(root->node, cow);
464
465 btrfs_free_tree_block(trans, root, buf, parent_start,
466 last_ref);
467 free_extent_buffer(buf);
468 add_root_to_dirty_list(root);
469 } else {
470 WARN_ON(trans->transid != btrfs_header_generation(parent));
471 btrfs_tree_mod_log_insert_key(parent, parent_slot,
472 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
473 btrfs_set_node_blockptr(parent, parent_slot,
474 cow->start);
475 btrfs_set_node_ptr_generation(parent, parent_slot,
476 trans->transid);
477 btrfs_mark_buffer_dirty(parent);
478 if (last_ref) {
479 ret = btrfs_tree_mod_log_free_eb(buf);
480 if (ret) {
481 btrfs_tree_unlock(cow);
482 free_extent_buffer(cow);
483 btrfs_abort_transaction(trans, ret);
484 return ret;
485 }
486 }
487 btrfs_free_tree_block(trans, root, buf, parent_start,
488 last_ref);
489 }
490 if (unlock_orig)
491 btrfs_tree_unlock(buf);
492 free_extent_buffer_stale(buf);
493 btrfs_mark_buffer_dirty(cow);
494 *cow_ret = cow;
495 return 0;
496}
497
498static inline int should_cow_block(struct btrfs_trans_handle *trans,
499 struct btrfs_root *root,
500 struct extent_buffer *buf)
501{
502 if (btrfs_is_testing(root->fs_info))
503 return 0;
504
505 /* Ensure we can see the FORCE_COW bit */
506 smp_mb__before_atomic();
507
508 /*
509 * We do not need to cow a block if
510 * 1) this block is not created or changed in this transaction;
511 * 2) this block does not belong to TREE_RELOC tree;
512 * 3) the root is not forced COW.
513 *
514 * What is forced COW:
515 * when we create snapshot during committing the transaction,
516 * after we've finished copying src root, we must COW the shared
517 * block to ensure the metadata consistency.
518 */
519 if (btrfs_header_generation(buf) == trans->transid &&
520 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
521 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
522 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
523 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
524 return 0;
525 return 1;
526}
527
528/*
529 * cows a single block, see __btrfs_cow_block for the real work.
530 * This version of it has extra checks so that a block isn't COWed more than
531 * once per transaction, as long as it hasn't been written yet
532 */
533noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
534 struct btrfs_root *root, struct extent_buffer *buf,
535 struct extent_buffer *parent, int parent_slot,
536 struct extent_buffer **cow_ret,
537 enum btrfs_lock_nesting nest)
538{
539 struct btrfs_fs_info *fs_info = root->fs_info;
540 u64 search_start;
541 int ret;
542
543 if (test_bit(BTRFS_ROOT_DELETING, &root->state))
544 btrfs_err(fs_info,
545 "COW'ing blocks on a fs root that's being dropped");
546
547 if (trans->transaction != fs_info->running_transaction)
548 WARN(1, KERN_CRIT "trans %llu running %llu\n",
549 trans->transid,
550 fs_info->running_transaction->transid);
551
552 if (trans->transid != fs_info->generation)
553 WARN(1, KERN_CRIT "trans %llu running %llu\n",
554 trans->transid, fs_info->generation);
555
556 if (!should_cow_block(trans, root, buf)) {
557 *cow_ret = buf;
558 return 0;
559 }
560
561 search_start = buf->start & ~((u64)SZ_1G - 1);
562
563 /*
564 * Before CoWing this block for later modification, check if it's
565 * the subtree root and do the delayed subtree trace if needed.
566 *
567 * Also We don't care about the error, as it's handled internally.
568 */
569 btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
570 ret = __btrfs_cow_block(trans, root, buf, parent,
571 parent_slot, cow_ret, search_start, 0, nest);
572
573 trace_btrfs_cow_block(root, buf, *cow_ret);
574
575 return ret;
576}
577ALLOW_ERROR_INJECTION(btrfs_cow_block, ERRNO);
578
579/*
580 * helper function for defrag to decide if two blocks pointed to by a
581 * node are actually close by
582 */
583static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
584{
585 if (blocknr < other && other - (blocknr + blocksize) < 32768)
586 return 1;
587 if (blocknr > other && blocknr - (other + blocksize) < 32768)
588 return 1;
589 return 0;
590}
591
592#ifdef __LITTLE_ENDIAN
593
594/*
595 * Compare two keys, on little-endian the disk order is same as CPU order and
596 * we can avoid the conversion.
597 */
598static int comp_keys(const struct btrfs_disk_key *disk_key,
599 const struct btrfs_key *k2)
600{
601 const struct btrfs_key *k1 = (const struct btrfs_key *)disk_key;
602
603 return btrfs_comp_cpu_keys(k1, k2);
604}
605
606#else
607
608/*
609 * compare two keys in a memcmp fashion
610 */
611static int comp_keys(const struct btrfs_disk_key *disk,
612 const struct btrfs_key *k2)
613{
614 struct btrfs_key k1;
615
616 btrfs_disk_key_to_cpu(&k1, disk);
617
618 return btrfs_comp_cpu_keys(&k1, k2);
619}
620#endif
621
622/*
623 * same as comp_keys only with two btrfs_key's
624 */
625int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
626{
627 if (k1->objectid > k2->objectid)
628 return 1;
629 if (k1->objectid < k2->objectid)
630 return -1;
631 if (k1->type > k2->type)
632 return 1;
633 if (k1->type < k2->type)
634 return -1;
635 if (k1->offset > k2->offset)
636 return 1;
637 if (k1->offset < k2->offset)
638 return -1;
639 return 0;
640}
641
642/*
643 * this is used by the defrag code to go through all the
644 * leaves pointed to by a node and reallocate them so that
645 * disk order is close to key order
646 */
647int btrfs_realloc_node(struct btrfs_trans_handle *trans,
648 struct btrfs_root *root, struct extent_buffer *parent,
649 int start_slot, u64 *last_ret,
650 struct btrfs_key *progress)
651{
652 struct btrfs_fs_info *fs_info = root->fs_info;
653 struct extent_buffer *cur;
654 u64 blocknr;
655 u64 search_start = *last_ret;
656 u64 last_block = 0;
657 u64 other;
658 u32 parent_nritems;
659 int end_slot;
660 int i;
661 int err = 0;
662 u32 blocksize;
663 int progress_passed = 0;
664 struct btrfs_disk_key disk_key;
665
666 WARN_ON(trans->transaction != fs_info->running_transaction);
667 WARN_ON(trans->transid != fs_info->generation);
668
669 parent_nritems = btrfs_header_nritems(parent);
670 blocksize = fs_info->nodesize;
671 end_slot = parent_nritems - 1;
672
673 if (parent_nritems <= 1)
674 return 0;
675
676 for (i = start_slot; i <= end_slot; i++) {
677 int close = 1;
678
679 btrfs_node_key(parent, &disk_key, i);
680 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
681 continue;
682
683 progress_passed = 1;
684 blocknr = btrfs_node_blockptr(parent, i);
685 if (last_block == 0)
686 last_block = blocknr;
687
688 if (i > 0) {
689 other = btrfs_node_blockptr(parent, i - 1);
690 close = close_blocks(blocknr, other, blocksize);
691 }
692 if (!close && i < end_slot) {
693 other = btrfs_node_blockptr(parent, i + 1);
694 close = close_blocks(blocknr, other, blocksize);
695 }
696 if (close) {
697 last_block = blocknr;
698 continue;
699 }
700
701 cur = btrfs_read_node_slot(parent, i);
702 if (IS_ERR(cur))
703 return PTR_ERR(cur);
704 if (search_start == 0)
705 search_start = last_block;
706
707 btrfs_tree_lock(cur);
708 err = __btrfs_cow_block(trans, root, cur, parent, i,
709 &cur, search_start,
710 min(16 * blocksize,
711 (end_slot - i) * blocksize),
712 BTRFS_NESTING_COW);
713 if (err) {
714 btrfs_tree_unlock(cur);
715 free_extent_buffer(cur);
716 break;
717 }
718 search_start = cur->start;
719 last_block = cur->start;
720 *last_ret = search_start;
721 btrfs_tree_unlock(cur);
722 free_extent_buffer(cur);
723 }
724 return err;
725}
726
727/*
728 * search for key in the extent_buffer. The items start at offset p,
729 * and they are item_size apart. There are 'max' items in p.
730 *
731 * the slot in the array is returned via slot, and it points to
732 * the place where you would insert key if it is not found in
733 * the array.
734 *
735 * slot may point to max if the key is bigger than all of the keys
736 */
737static noinline int generic_bin_search(struct extent_buffer *eb,
738 unsigned long p, int item_size,
739 const struct btrfs_key *key,
740 int max, int *slot)
741{
742 int low = 0;
743 int high = max;
744 int ret;
745 const int key_size = sizeof(struct btrfs_disk_key);
746
747 if (low > high) {
748 btrfs_err(eb->fs_info,
749 "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
750 __func__, low, high, eb->start,
751 btrfs_header_owner(eb), btrfs_header_level(eb));
752 return -EINVAL;
753 }
754
755 while (low < high) {
756 unsigned long oip;
757 unsigned long offset;
758 struct btrfs_disk_key *tmp;
759 struct btrfs_disk_key unaligned;
760 int mid;
761
762 mid = (low + high) / 2;
763 offset = p + mid * item_size;
764 oip = offset_in_page(offset);
765
766 if (oip + key_size <= PAGE_SIZE) {
767 const unsigned long idx = get_eb_page_index(offset);
768 char *kaddr = page_address(eb->pages[idx]);
769
770 oip = get_eb_offset_in_page(eb, offset);
771 tmp = (struct btrfs_disk_key *)(kaddr + oip);
772 } else {
773 read_extent_buffer(eb, &unaligned, offset, key_size);
774 tmp = &unaligned;
775 }
776
777 ret = comp_keys(tmp, key);
778
779 if (ret < 0)
780 low = mid + 1;
781 else if (ret > 0)
782 high = mid;
783 else {
784 *slot = mid;
785 return 0;
786 }
787 }
788 *slot = low;
789 return 1;
790}
791
792/*
793 * simple bin_search frontend that does the right thing for
794 * leaves vs nodes
795 */
796int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
797 int *slot)
798{
799 if (btrfs_header_level(eb) == 0)
800 return generic_bin_search(eb,
801 offsetof(struct btrfs_leaf, items),
802 sizeof(struct btrfs_item),
803 key, btrfs_header_nritems(eb),
804 slot);
805 else
806 return generic_bin_search(eb,
807 offsetof(struct btrfs_node, ptrs),
808 sizeof(struct btrfs_key_ptr),
809 key, btrfs_header_nritems(eb),
810 slot);
811}
812
813static void root_add_used(struct btrfs_root *root, u32 size)
814{
815 spin_lock(&root->accounting_lock);
816 btrfs_set_root_used(&root->root_item,
817 btrfs_root_used(&root->root_item) + size);
818 spin_unlock(&root->accounting_lock);
819}
820
821static void root_sub_used(struct btrfs_root *root, u32 size)
822{
823 spin_lock(&root->accounting_lock);
824 btrfs_set_root_used(&root->root_item,
825 btrfs_root_used(&root->root_item) - size);
826 spin_unlock(&root->accounting_lock);
827}
828
829/* given a node and slot number, this reads the blocks it points to. The
830 * extent buffer is returned with a reference taken (but unlocked).
831 */
832struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
833 int slot)
834{
835 int level = btrfs_header_level(parent);
836 struct extent_buffer *eb;
837 struct btrfs_key first_key;
838
839 if (slot < 0 || slot >= btrfs_header_nritems(parent))
840 return ERR_PTR(-ENOENT);
841
842 BUG_ON(level == 0);
843
844 btrfs_node_key_to_cpu(parent, &first_key, slot);
845 eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
846 btrfs_header_owner(parent),
847 btrfs_node_ptr_generation(parent, slot),
848 level - 1, &first_key);
849 if (!IS_ERR(eb) && !extent_buffer_uptodate(eb)) {
850 free_extent_buffer(eb);
851 eb = ERR_PTR(-EIO);
852 }
853
854 return eb;
855}
856
857/*
858 * node level balancing, used to make sure nodes are in proper order for
859 * item deletion. We balance from the top down, so we have to make sure
860 * that a deletion won't leave an node completely empty later on.
861 */
862static noinline int balance_level(struct btrfs_trans_handle *trans,
863 struct btrfs_root *root,
864 struct btrfs_path *path, int level)
865{
866 struct btrfs_fs_info *fs_info = root->fs_info;
867 struct extent_buffer *right = NULL;
868 struct extent_buffer *mid;
869 struct extent_buffer *left = NULL;
870 struct extent_buffer *parent = NULL;
871 int ret = 0;
872 int wret;
873 int pslot;
874 int orig_slot = path->slots[level];
875 u64 orig_ptr;
876
877 ASSERT(level > 0);
878
879 mid = path->nodes[level];
880
881 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK);
882 WARN_ON(btrfs_header_generation(mid) != trans->transid);
883
884 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
885
886 if (level < BTRFS_MAX_LEVEL - 1) {
887 parent = path->nodes[level + 1];
888 pslot = path->slots[level + 1];
889 }
890
891 /*
892 * deal with the case where there is only one pointer in the root
893 * by promoting the node below to a root
894 */
895 if (!parent) {
896 struct extent_buffer *child;
897
898 if (btrfs_header_nritems(mid) != 1)
899 return 0;
900
901 /* promote the child to a root */
902 child = btrfs_read_node_slot(mid, 0);
903 if (IS_ERR(child)) {
904 ret = PTR_ERR(child);
905 btrfs_handle_fs_error(fs_info, ret, NULL);
906 goto enospc;
907 }
908
909 btrfs_tree_lock(child);
910 ret = btrfs_cow_block(trans, root, child, mid, 0, &child,
911 BTRFS_NESTING_COW);
912 if (ret) {
913 btrfs_tree_unlock(child);
914 free_extent_buffer(child);
915 goto enospc;
916 }
917
918 ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
919 BUG_ON(ret < 0);
920 rcu_assign_pointer(root->node, child);
921
922 add_root_to_dirty_list(root);
923 btrfs_tree_unlock(child);
924
925 path->locks[level] = 0;
926 path->nodes[level] = NULL;
927 btrfs_clean_tree_block(mid);
928 btrfs_tree_unlock(mid);
929 /* once for the path */
930 free_extent_buffer(mid);
931
932 root_sub_used(root, mid->len);
933 btrfs_free_tree_block(trans, root, mid, 0, 1);
934 /* once for the root ptr */
935 free_extent_buffer_stale(mid);
936 return 0;
937 }
938 if (btrfs_header_nritems(mid) >
939 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
940 return 0;
941
942 left = btrfs_read_node_slot(parent, pslot - 1);
943 if (IS_ERR(left))
944 left = NULL;
945
946 if (left) {
947 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
948 wret = btrfs_cow_block(trans, root, left,
949 parent, pslot - 1, &left,
950 BTRFS_NESTING_LEFT_COW);
951 if (wret) {
952 ret = wret;
953 goto enospc;
954 }
955 }
956
957 right = btrfs_read_node_slot(parent, pslot + 1);
958 if (IS_ERR(right))
959 right = NULL;
960
961 if (right) {
962 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
963 wret = btrfs_cow_block(trans, root, right,
964 parent, pslot + 1, &right,
965 BTRFS_NESTING_RIGHT_COW);
966 if (wret) {
967 ret = wret;
968 goto enospc;
969 }
970 }
971
972 /* first, try to make some room in the middle buffer */
973 if (left) {
974 orig_slot += btrfs_header_nritems(left);
975 wret = push_node_left(trans, left, mid, 1);
976 if (wret < 0)
977 ret = wret;
978 }
979
980 /*
981 * then try to empty the right most buffer into the middle
982 */
983 if (right) {
984 wret = push_node_left(trans, mid, right, 1);
985 if (wret < 0 && wret != -ENOSPC)
986 ret = wret;
987 if (btrfs_header_nritems(right) == 0) {
988 btrfs_clean_tree_block(right);
989 btrfs_tree_unlock(right);
990 del_ptr(root, path, level + 1, pslot + 1);
991 root_sub_used(root, right->len);
992 btrfs_free_tree_block(trans, root, right, 0, 1);
993 free_extent_buffer_stale(right);
994 right = NULL;
995 } else {
996 struct btrfs_disk_key right_key;
997 btrfs_node_key(right, &right_key, 0);
998 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
999 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1000 BUG_ON(ret < 0);
1001 btrfs_set_node_key(parent, &right_key, pslot + 1);
1002 btrfs_mark_buffer_dirty(parent);
1003 }
1004 }
1005 if (btrfs_header_nritems(mid) == 1) {
1006 /*
1007 * we're not allowed to leave a node with one item in the
1008 * tree during a delete. A deletion from lower in the tree
1009 * could try to delete the only pointer in this node.
1010 * So, pull some keys from the left.
1011 * There has to be a left pointer at this point because
1012 * otherwise we would have pulled some pointers from the
1013 * right
1014 */
1015 if (!left) {
1016 ret = -EROFS;
1017 btrfs_handle_fs_error(fs_info, ret, NULL);
1018 goto enospc;
1019 }
1020 wret = balance_node_right(trans, mid, left);
1021 if (wret < 0) {
1022 ret = wret;
1023 goto enospc;
1024 }
1025 if (wret == 1) {
1026 wret = push_node_left(trans, left, mid, 1);
1027 if (wret < 0)
1028 ret = wret;
1029 }
1030 BUG_ON(wret == 1);
1031 }
1032 if (btrfs_header_nritems(mid) == 0) {
1033 btrfs_clean_tree_block(mid);
1034 btrfs_tree_unlock(mid);
1035 del_ptr(root, path, level + 1, pslot);
1036 root_sub_used(root, mid->len);
1037 btrfs_free_tree_block(trans, root, mid, 0, 1);
1038 free_extent_buffer_stale(mid);
1039 mid = NULL;
1040 } else {
1041 /* update the parent key to reflect our changes */
1042 struct btrfs_disk_key mid_key;
1043 btrfs_node_key(mid, &mid_key, 0);
1044 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1045 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1046 BUG_ON(ret < 0);
1047 btrfs_set_node_key(parent, &mid_key, pslot);
1048 btrfs_mark_buffer_dirty(parent);
1049 }
1050
1051 /* update the path */
1052 if (left) {
1053 if (btrfs_header_nritems(left) > orig_slot) {
1054 atomic_inc(&left->refs);
1055 /* left was locked after cow */
1056 path->nodes[level] = left;
1057 path->slots[level + 1] -= 1;
1058 path->slots[level] = orig_slot;
1059 if (mid) {
1060 btrfs_tree_unlock(mid);
1061 free_extent_buffer(mid);
1062 }
1063 } else {
1064 orig_slot -= btrfs_header_nritems(left);
1065 path->slots[level] = orig_slot;
1066 }
1067 }
1068 /* double check we haven't messed things up */
1069 if (orig_ptr !=
1070 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1071 BUG();
1072enospc:
1073 if (right) {
1074 btrfs_tree_unlock(right);
1075 free_extent_buffer(right);
1076 }
1077 if (left) {
1078 if (path->nodes[level] != left)
1079 btrfs_tree_unlock(left);
1080 free_extent_buffer(left);
1081 }
1082 return ret;
1083}
1084
1085/* Node balancing for insertion. Here we only split or push nodes around
1086 * when they are completely full. This is also done top down, so we
1087 * have to be pessimistic.
1088 */
1089static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1090 struct btrfs_root *root,
1091 struct btrfs_path *path, int level)
1092{
1093 struct btrfs_fs_info *fs_info = root->fs_info;
1094 struct extent_buffer *right = NULL;
1095 struct extent_buffer *mid;
1096 struct extent_buffer *left = NULL;
1097 struct extent_buffer *parent = NULL;
1098 int ret = 0;
1099 int wret;
1100 int pslot;
1101 int orig_slot = path->slots[level];
1102
1103 if (level == 0)
1104 return 1;
1105
1106 mid = path->nodes[level];
1107 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1108
1109 if (level < BTRFS_MAX_LEVEL - 1) {
1110 parent = path->nodes[level + 1];
1111 pslot = path->slots[level + 1];
1112 }
1113
1114 if (!parent)
1115 return 1;
1116
1117 left = btrfs_read_node_slot(parent, pslot - 1);
1118 if (IS_ERR(left))
1119 left = NULL;
1120
1121 /* first, try to make some room in the middle buffer */
1122 if (left) {
1123 u32 left_nr;
1124
1125 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
1126
1127 left_nr = btrfs_header_nritems(left);
1128 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1129 wret = 1;
1130 } else {
1131 ret = btrfs_cow_block(trans, root, left, parent,
1132 pslot - 1, &left,
1133 BTRFS_NESTING_LEFT_COW);
1134 if (ret)
1135 wret = 1;
1136 else {
1137 wret = push_node_left(trans, left, mid, 0);
1138 }
1139 }
1140 if (wret < 0)
1141 ret = wret;
1142 if (wret == 0) {
1143 struct btrfs_disk_key disk_key;
1144 orig_slot += left_nr;
1145 btrfs_node_key(mid, &disk_key, 0);
1146 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1147 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1148 BUG_ON(ret < 0);
1149 btrfs_set_node_key(parent, &disk_key, pslot);
1150 btrfs_mark_buffer_dirty(parent);
1151 if (btrfs_header_nritems(left) > orig_slot) {
1152 path->nodes[level] = left;
1153 path->slots[level + 1] -= 1;
1154 path->slots[level] = orig_slot;
1155 btrfs_tree_unlock(mid);
1156 free_extent_buffer(mid);
1157 } else {
1158 orig_slot -=
1159 btrfs_header_nritems(left);
1160 path->slots[level] = orig_slot;
1161 btrfs_tree_unlock(left);
1162 free_extent_buffer(left);
1163 }
1164 return 0;
1165 }
1166 btrfs_tree_unlock(left);
1167 free_extent_buffer(left);
1168 }
1169 right = btrfs_read_node_slot(parent, pslot + 1);
1170 if (IS_ERR(right))
1171 right = NULL;
1172
1173 /*
1174 * then try to empty the right most buffer into the middle
1175 */
1176 if (right) {
1177 u32 right_nr;
1178
1179 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
1180
1181 right_nr = btrfs_header_nritems(right);
1182 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1183 wret = 1;
1184 } else {
1185 ret = btrfs_cow_block(trans, root, right,
1186 parent, pslot + 1,
1187 &right, BTRFS_NESTING_RIGHT_COW);
1188 if (ret)
1189 wret = 1;
1190 else {
1191 wret = balance_node_right(trans, right, mid);
1192 }
1193 }
1194 if (wret < 0)
1195 ret = wret;
1196 if (wret == 0) {
1197 struct btrfs_disk_key disk_key;
1198
1199 btrfs_node_key(right, &disk_key, 0);
1200 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1201 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1202 BUG_ON(ret < 0);
1203 btrfs_set_node_key(parent, &disk_key, pslot + 1);
1204 btrfs_mark_buffer_dirty(parent);
1205
1206 if (btrfs_header_nritems(mid) <= orig_slot) {
1207 path->nodes[level] = right;
1208 path->slots[level + 1] += 1;
1209 path->slots[level] = orig_slot -
1210 btrfs_header_nritems(mid);
1211 btrfs_tree_unlock(mid);
1212 free_extent_buffer(mid);
1213 } else {
1214 btrfs_tree_unlock(right);
1215 free_extent_buffer(right);
1216 }
1217 return 0;
1218 }
1219 btrfs_tree_unlock(right);
1220 free_extent_buffer(right);
1221 }
1222 return 1;
1223}
1224
1225/*
1226 * readahead one full node of leaves, finding things that are close
1227 * to the block in 'slot', and triggering ra on them.
1228 */
1229static void reada_for_search(struct btrfs_fs_info *fs_info,
1230 struct btrfs_path *path,
1231 int level, int slot, u64 objectid)
1232{
1233 struct extent_buffer *node;
1234 struct btrfs_disk_key disk_key;
1235 u32 nritems;
1236 u64 search;
1237 u64 target;
1238 u64 nread = 0;
1239 u64 nread_max;
1240 struct extent_buffer *eb;
1241 u32 nr;
1242 u32 blocksize;
1243 u32 nscan = 0;
1244
1245 if (level != 1 && path->reada != READA_FORWARD_ALWAYS)
1246 return;
1247
1248 if (!path->nodes[level])
1249 return;
1250
1251 node = path->nodes[level];
1252
1253 /*
1254 * Since the time between visiting leaves is much shorter than the time
1255 * between visiting nodes, limit read ahead of nodes to 1, to avoid too
1256 * much IO at once (possibly random).
1257 */
1258 if (path->reada == READA_FORWARD_ALWAYS) {
1259 if (level > 1)
1260 nread_max = node->fs_info->nodesize;
1261 else
1262 nread_max = SZ_128K;
1263 } else {
1264 nread_max = SZ_64K;
1265 }
1266
1267 search = btrfs_node_blockptr(node, slot);
1268 blocksize = fs_info->nodesize;
1269 eb = find_extent_buffer(fs_info, search);
1270 if (eb) {
1271 free_extent_buffer(eb);
1272 return;
1273 }
1274
1275 target = search;
1276
1277 nritems = btrfs_header_nritems(node);
1278 nr = slot;
1279
1280 while (1) {
1281 if (path->reada == READA_BACK) {
1282 if (nr == 0)
1283 break;
1284 nr--;
1285 } else if (path->reada == READA_FORWARD ||
1286 path->reada == READA_FORWARD_ALWAYS) {
1287 nr++;
1288 if (nr >= nritems)
1289 break;
1290 }
1291 if (path->reada == READA_BACK && objectid) {
1292 btrfs_node_key(node, &disk_key, nr);
1293 if (btrfs_disk_key_objectid(&disk_key) != objectid)
1294 break;
1295 }
1296 search = btrfs_node_blockptr(node, nr);
1297 if (path->reada == READA_FORWARD_ALWAYS ||
1298 (search <= target && target - search <= 65536) ||
1299 (search > target && search - target <= 65536)) {
1300 btrfs_readahead_node_child(node, nr);
1301 nread += blocksize;
1302 }
1303 nscan++;
1304 if (nread > nread_max || nscan > 32)
1305 break;
1306 }
1307}
1308
1309static noinline void reada_for_balance(struct btrfs_path *path, int level)
1310{
1311 struct extent_buffer *parent;
1312 int slot;
1313 int nritems;
1314
1315 parent = path->nodes[level + 1];
1316 if (!parent)
1317 return;
1318
1319 nritems = btrfs_header_nritems(parent);
1320 slot = path->slots[level + 1];
1321
1322 if (slot > 0)
1323 btrfs_readahead_node_child(parent, slot - 1);
1324 if (slot + 1 < nritems)
1325 btrfs_readahead_node_child(parent, slot + 1);
1326}
1327
1328
1329/*
1330 * when we walk down the tree, it is usually safe to unlock the higher layers
1331 * in the tree. The exceptions are when our path goes through slot 0, because
1332 * operations on the tree might require changing key pointers higher up in the
1333 * tree.
1334 *
1335 * callers might also have set path->keep_locks, which tells this code to keep
1336 * the lock if the path points to the last slot in the block. This is part of
1337 * walking through the tree, and selecting the next slot in the higher block.
1338 *
1339 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
1340 * if lowest_unlock is 1, level 0 won't be unlocked
1341 */
1342static noinline void unlock_up(struct btrfs_path *path, int level,
1343 int lowest_unlock, int min_write_lock_level,
1344 int *write_lock_level)
1345{
1346 int i;
1347 int skip_level = level;
1348 int no_skips = 0;
1349 struct extent_buffer *t;
1350
1351 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1352 if (!path->nodes[i])
1353 break;
1354 if (!path->locks[i])
1355 break;
1356 if (!no_skips && path->slots[i] == 0) {
1357 skip_level = i + 1;
1358 continue;
1359 }
1360 if (!no_skips && path->keep_locks) {
1361 u32 nritems;
1362 t = path->nodes[i];
1363 nritems = btrfs_header_nritems(t);
1364 if (nritems < 1 || path->slots[i] >= nritems - 1) {
1365 skip_level = i + 1;
1366 continue;
1367 }
1368 }
1369 if (skip_level < i && i >= lowest_unlock)
1370 no_skips = 1;
1371
1372 t = path->nodes[i];
1373 if (i >= lowest_unlock && i > skip_level) {
1374 btrfs_tree_unlock_rw(t, path->locks[i]);
1375 path->locks[i] = 0;
1376 if (write_lock_level &&
1377 i > min_write_lock_level &&
1378 i <= *write_lock_level) {
1379 *write_lock_level = i - 1;
1380 }
1381 }
1382 }
1383}
1384
1385/*
1386 * helper function for btrfs_search_slot. The goal is to find a block
1387 * in cache without setting the path to blocking. If we find the block
1388 * we return zero and the path is unchanged.
1389 *
1390 * If we can't find the block, we set the path blocking and do some
1391 * reada. -EAGAIN is returned and the search must be repeated.
1392 */
1393static int
1394read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
1395 struct extent_buffer **eb_ret, int level, int slot,
1396 const struct btrfs_key *key)
1397{
1398 struct btrfs_fs_info *fs_info = root->fs_info;
1399 u64 blocknr;
1400 u64 gen;
1401 struct extent_buffer *tmp;
1402 struct btrfs_key first_key;
1403 int ret;
1404 int parent_level;
1405
1406 blocknr = btrfs_node_blockptr(*eb_ret, slot);
1407 gen = btrfs_node_ptr_generation(*eb_ret, slot);
1408 parent_level = btrfs_header_level(*eb_ret);
1409 btrfs_node_key_to_cpu(*eb_ret, &first_key, slot);
1410
1411 tmp = find_extent_buffer(fs_info, blocknr);
1412 if (tmp) {
1413 if (p->reada == READA_FORWARD_ALWAYS)
1414 reada_for_search(fs_info, p, level, slot, key->objectid);
1415
1416 /* first we do an atomic uptodate check */
1417 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
1418 /*
1419 * Do extra check for first_key, eb can be stale due to
1420 * being cached, read from scrub, or have multiple
1421 * parents (shared tree blocks).
1422 */
1423 if (btrfs_verify_level_key(tmp,
1424 parent_level - 1, &first_key, gen)) {
1425 free_extent_buffer(tmp);
1426 return -EUCLEAN;
1427 }
1428 *eb_ret = tmp;
1429 return 0;
1430 }
1431
1432 /* now we're allowed to do a blocking uptodate check */
1433 ret = btrfs_read_buffer(tmp, gen, parent_level - 1, &first_key);
1434 if (!ret) {
1435 *eb_ret = tmp;
1436 return 0;
1437 }
1438 free_extent_buffer(tmp);
1439 btrfs_release_path(p);
1440 return -EIO;
1441 }
1442
1443 /*
1444 * reduce lock contention at high levels
1445 * of the btree by dropping locks before
1446 * we read. Don't release the lock on the current
1447 * level because we need to walk this node to figure
1448 * out which blocks to read.
1449 */
1450 btrfs_unlock_up_safe(p, level + 1);
1451
1452 if (p->reada != READA_NONE)
1453 reada_for_search(fs_info, p, level, slot, key->objectid);
1454
1455 ret = -EAGAIN;
1456 tmp = read_tree_block(fs_info, blocknr, root->root_key.objectid,
1457 gen, parent_level - 1, &first_key);
1458 if (!IS_ERR(tmp)) {
1459 /*
1460 * If the read above didn't mark this buffer up to date,
1461 * it will never end up being up to date. Set ret to EIO now
1462 * and give up so that our caller doesn't loop forever
1463 * on our EAGAINs.
1464 */
1465 if (!extent_buffer_uptodate(tmp))
1466 ret = -EIO;
1467 free_extent_buffer(tmp);
1468 } else {
1469 ret = PTR_ERR(tmp);
1470 }
1471
1472 btrfs_release_path(p);
1473 return ret;
1474}
1475
1476/*
1477 * helper function for btrfs_search_slot. This does all of the checks
1478 * for node-level blocks and does any balancing required based on
1479 * the ins_len.
1480 *
1481 * If no extra work was required, zero is returned. If we had to
1482 * drop the path, -EAGAIN is returned and btrfs_search_slot must
1483 * start over
1484 */
1485static int
1486setup_nodes_for_search(struct btrfs_trans_handle *trans,
1487 struct btrfs_root *root, struct btrfs_path *p,
1488 struct extent_buffer *b, int level, int ins_len,
1489 int *write_lock_level)
1490{
1491 struct btrfs_fs_info *fs_info = root->fs_info;
1492 int ret = 0;
1493
1494 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
1495 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
1496
1497 if (*write_lock_level < level + 1) {
1498 *write_lock_level = level + 1;
1499 btrfs_release_path(p);
1500 return -EAGAIN;
1501 }
1502
1503 reada_for_balance(p, level);
1504 ret = split_node(trans, root, p, level);
1505
1506 b = p->nodes[level];
1507 } else if (ins_len < 0 && btrfs_header_nritems(b) <
1508 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
1509
1510 if (*write_lock_level < level + 1) {
1511 *write_lock_level = level + 1;
1512 btrfs_release_path(p);
1513 return -EAGAIN;
1514 }
1515
1516 reada_for_balance(p, level);
1517 ret = balance_level(trans, root, p, level);
1518 if (ret)
1519 return ret;
1520
1521 b = p->nodes[level];
1522 if (!b) {
1523 btrfs_release_path(p);
1524 return -EAGAIN;
1525 }
1526 BUG_ON(btrfs_header_nritems(b) == 1);
1527 }
1528 return ret;
1529}
1530
1531int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
1532 u64 iobjectid, u64 ioff, u8 key_type,
1533 struct btrfs_key *found_key)
1534{
1535 int ret;
1536 struct btrfs_key key;
1537 struct extent_buffer *eb;
1538
1539 ASSERT(path);
1540 ASSERT(found_key);
1541
1542 key.type = key_type;
1543 key.objectid = iobjectid;
1544 key.offset = ioff;
1545
1546 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1547 if (ret < 0)
1548 return ret;
1549
1550 eb = path->nodes[0];
1551 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1552 ret = btrfs_next_leaf(fs_root, path);
1553 if (ret)
1554 return ret;
1555 eb = path->nodes[0];
1556 }
1557
1558 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1559 if (found_key->type != key.type ||
1560 found_key->objectid != key.objectid)
1561 return 1;
1562
1563 return 0;
1564}
1565
1566static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
1567 struct btrfs_path *p,
1568 int write_lock_level)
1569{
1570 struct btrfs_fs_info *fs_info = root->fs_info;
1571 struct extent_buffer *b;
1572 int root_lock;
1573 int level = 0;
1574
1575 /* We try very hard to do read locks on the root */
1576 root_lock = BTRFS_READ_LOCK;
1577
1578 if (p->search_commit_root) {
1579 /*
1580 * The commit roots are read only so we always do read locks,
1581 * and we always must hold the commit_root_sem when doing
1582 * searches on them, the only exception is send where we don't
1583 * want to block transaction commits for a long time, so
1584 * we need to clone the commit root in order to avoid races
1585 * with transaction commits that create a snapshot of one of
1586 * the roots used by a send operation.
1587 */
1588 if (p->need_commit_sem) {
1589 down_read(&fs_info->commit_root_sem);
1590 b = btrfs_clone_extent_buffer(root->commit_root);
1591 up_read(&fs_info->commit_root_sem);
1592 if (!b)
1593 return ERR_PTR(-ENOMEM);
1594
1595 } else {
1596 b = root->commit_root;
1597 atomic_inc(&b->refs);
1598 }
1599 level = btrfs_header_level(b);
1600 /*
1601 * Ensure that all callers have set skip_locking when
1602 * p->search_commit_root = 1.
1603 */
1604 ASSERT(p->skip_locking == 1);
1605
1606 goto out;
1607 }
1608
1609 if (p->skip_locking) {
1610 b = btrfs_root_node(root);
1611 level = btrfs_header_level(b);
1612 goto out;
1613 }
1614
1615 /*
1616 * If the level is set to maximum, we can skip trying to get the read
1617 * lock.
1618 */
1619 if (write_lock_level < BTRFS_MAX_LEVEL) {
1620 /*
1621 * We don't know the level of the root node until we actually
1622 * have it read locked
1623 */
1624 b = btrfs_read_lock_root_node(root);
1625 level = btrfs_header_level(b);
1626 if (level > write_lock_level)
1627 goto out;
1628
1629 /* Whoops, must trade for write lock */
1630 btrfs_tree_read_unlock(b);
1631 free_extent_buffer(b);
1632 }
1633
1634 b = btrfs_lock_root_node(root);
1635 root_lock = BTRFS_WRITE_LOCK;
1636
1637 /* The level might have changed, check again */
1638 level = btrfs_header_level(b);
1639
1640out:
1641 p->nodes[level] = b;
1642 if (!p->skip_locking)
1643 p->locks[level] = root_lock;
1644 /*
1645 * Callers are responsible for dropping b's references.
1646 */
1647 return b;
1648}
1649
1650
1651/*
1652 * btrfs_search_slot - look for a key in a tree and perform necessary
1653 * modifications to preserve tree invariants.
1654 *
1655 * @trans: Handle of transaction, used when modifying the tree
1656 * @p: Holds all btree nodes along the search path
1657 * @root: The root node of the tree
1658 * @key: The key we are looking for
1659 * @ins_len: Indicates purpose of search:
1660 * >0 for inserts it's size of item inserted (*)
1661 * <0 for deletions
1662 * 0 for plain searches, not modifying the tree
1663 *
1664 * (*) If size of item inserted doesn't include
1665 * sizeof(struct btrfs_item), then p->search_for_extension must
1666 * be set.
1667 * @cow: boolean should CoW operations be performed. Must always be 1
1668 * when modifying the tree.
1669 *
1670 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
1671 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
1672 *
1673 * If @key is found, 0 is returned and you can find the item in the leaf level
1674 * of the path (level 0)
1675 *
1676 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
1677 * points to the slot where it should be inserted
1678 *
1679 * If an error is encountered while searching the tree a negative error number
1680 * is returned
1681 */
1682int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1683 const struct btrfs_key *key, struct btrfs_path *p,
1684 int ins_len, int cow)
1685{
1686 struct extent_buffer *b;
1687 int slot;
1688 int ret;
1689 int err;
1690 int level;
1691 int lowest_unlock = 1;
1692 /* everything at write_lock_level or lower must be write locked */
1693 int write_lock_level = 0;
1694 u8 lowest_level = 0;
1695 int min_write_lock_level;
1696 int prev_cmp;
1697
1698 lowest_level = p->lowest_level;
1699 WARN_ON(lowest_level && ins_len > 0);
1700 WARN_ON(p->nodes[0] != NULL);
1701 BUG_ON(!cow && ins_len);
1702
1703 if (ins_len < 0) {
1704 lowest_unlock = 2;
1705
1706 /* when we are removing items, we might have to go up to level
1707 * two as we update tree pointers Make sure we keep write
1708 * for those levels as well
1709 */
1710 write_lock_level = 2;
1711 } else if (ins_len > 0) {
1712 /*
1713 * for inserting items, make sure we have a write lock on
1714 * level 1 so we can update keys
1715 */
1716 write_lock_level = 1;
1717 }
1718
1719 if (!cow)
1720 write_lock_level = -1;
1721
1722 if (cow && (p->keep_locks || p->lowest_level))
1723 write_lock_level = BTRFS_MAX_LEVEL;
1724
1725 min_write_lock_level = write_lock_level;
1726
1727again:
1728 prev_cmp = -1;
1729 b = btrfs_search_slot_get_root(root, p, write_lock_level);
1730 if (IS_ERR(b)) {
1731 ret = PTR_ERR(b);
1732 goto done;
1733 }
1734
1735 while (b) {
1736 int dec = 0;
1737
1738 level = btrfs_header_level(b);
1739
1740 if (cow) {
1741 bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
1742
1743 /*
1744 * if we don't really need to cow this block
1745 * then we don't want to set the path blocking,
1746 * so we test it here
1747 */
1748 if (!should_cow_block(trans, root, b))
1749 goto cow_done;
1750
1751 /*
1752 * must have write locks on this node and the
1753 * parent
1754 */
1755 if (level > write_lock_level ||
1756 (level + 1 > write_lock_level &&
1757 level + 1 < BTRFS_MAX_LEVEL &&
1758 p->nodes[level + 1])) {
1759 write_lock_level = level + 1;
1760 btrfs_release_path(p);
1761 goto again;
1762 }
1763
1764 if (last_level)
1765 err = btrfs_cow_block(trans, root, b, NULL, 0,
1766 &b,
1767 BTRFS_NESTING_COW);
1768 else
1769 err = btrfs_cow_block(trans, root, b,
1770 p->nodes[level + 1],
1771 p->slots[level + 1], &b,
1772 BTRFS_NESTING_COW);
1773 if (err) {
1774 ret = err;
1775 goto done;
1776 }
1777 }
1778cow_done:
1779 p->nodes[level] = b;
1780 /*
1781 * Leave path with blocking locks to avoid massive
1782 * lock context switch, this is made on purpose.
1783 */
1784
1785 /*
1786 * we have a lock on b and as long as we aren't changing
1787 * the tree, there is no way to for the items in b to change.
1788 * It is safe to drop the lock on our parent before we
1789 * go through the expensive btree search on b.
1790 *
1791 * If we're inserting or deleting (ins_len != 0), then we might
1792 * be changing slot zero, which may require changing the parent.
1793 * So, we can't drop the lock until after we know which slot
1794 * we're operating on.
1795 */
1796 if (!ins_len && !p->keep_locks) {
1797 int u = level + 1;
1798
1799 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
1800 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
1801 p->locks[u] = 0;
1802 }
1803 }
1804
1805 /*
1806 * If btrfs_bin_search returns an exact match (prev_cmp == 0)
1807 * we can safely assume the target key will always be in slot 0
1808 * on lower levels due to the invariants BTRFS' btree provides,
1809 * namely that a btrfs_key_ptr entry always points to the
1810 * lowest key in the child node, thus we can skip searching
1811 * lower levels
1812 */
1813 if (prev_cmp == 0) {
1814 slot = 0;
1815 ret = 0;
1816 } else {
1817 ret = btrfs_bin_search(b, key, &slot);
1818 prev_cmp = ret;
1819 if (ret < 0)
1820 goto done;
1821 }
1822
1823 if (level == 0) {
1824 p->slots[level] = slot;
1825 /*
1826 * Item key already exists. In this case, if we are
1827 * allowed to insert the item (for example, in dir_item
1828 * case, item key collision is allowed), it will be
1829 * merged with the original item. Only the item size
1830 * grows, no new btrfs item will be added. If
1831 * search_for_extension is not set, ins_len already
1832 * accounts the size btrfs_item, deduct it here so leaf
1833 * space check will be correct.
1834 */
1835 if (ret == 0 && ins_len > 0 && !p->search_for_extension) {
1836 ASSERT(ins_len >= sizeof(struct btrfs_item));
1837 ins_len -= sizeof(struct btrfs_item);
1838 }
1839 if (ins_len > 0 &&
1840 btrfs_leaf_free_space(b) < ins_len) {
1841 if (write_lock_level < 1) {
1842 write_lock_level = 1;
1843 btrfs_release_path(p);
1844 goto again;
1845 }
1846
1847 err = split_leaf(trans, root, key,
1848 p, ins_len, ret == 0);
1849
1850 BUG_ON(err > 0);
1851 if (err) {
1852 ret = err;
1853 goto done;
1854 }
1855 }
1856 if (!p->search_for_split)
1857 unlock_up(p, level, lowest_unlock,
1858 min_write_lock_level, NULL);
1859 goto done;
1860 }
1861 if (ret && slot > 0) {
1862 dec = 1;
1863 slot--;
1864 }
1865 p->slots[level] = slot;
1866 err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
1867 &write_lock_level);
1868 if (err == -EAGAIN)
1869 goto again;
1870 if (err) {
1871 ret = err;
1872 goto done;
1873 }
1874 b = p->nodes[level];
1875 slot = p->slots[level];
1876
1877 /*
1878 * Slot 0 is special, if we change the key we have to update
1879 * the parent pointer which means we must have a write lock on
1880 * the parent
1881 */
1882 if (slot == 0 && ins_len && write_lock_level < level + 1) {
1883 write_lock_level = level + 1;
1884 btrfs_release_path(p);
1885 goto again;
1886 }
1887
1888 unlock_up(p, level, lowest_unlock, min_write_lock_level,
1889 &write_lock_level);
1890
1891 if (level == lowest_level) {
1892 if (dec)
1893 p->slots[level]++;
1894 goto done;
1895 }
1896
1897 err = read_block_for_search(root, p, &b, level, slot, key);
1898 if (err == -EAGAIN)
1899 goto again;
1900 if (err) {
1901 ret = err;
1902 goto done;
1903 }
1904
1905 if (!p->skip_locking) {
1906 level = btrfs_header_level(b);
1907 if (level <= write_lock_level) {
1908 btrfs_tree_lock(b);
1909 p->locks[level] = BTRFS_WRITE_LOCK;
1910 } else {
1911 btrfs_tree_read_lock(b);
1912 p->locks[level] = BTRFS_READ_LOCK;
1913 }
1914 p->nodes[level] = b;
1915 }
1916 }
1917 ret = 1;
1918done:
1919 if (ret < 0 && !p->skip_release_on_error)
1920 btrfs_release_path(p);
1921 return ret;
1922}
1923ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO);
1924
1925/*
1926 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
1927 * current state of the tree together with the operations recorded in the tree
1928 * modification log to search for the key in a previous version of this tree, as
1929 * denoted by the time_seq parameter.
1930 *
1931 * Naturally, there is no support for insert, delete or cow operations.
1932 *
1933 * The resulting path and return value will be set up as if we called
1934 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
1935 */
1936int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
1937 struct btrfs_path *p, u64 time_seq)
1938{
1939 struct btrfs_fs_info *fs_info = root->fs_info;
1940 struct extent_buffer *b;
1941 int slot;
1942 int ret;
1943 int err;
1944 int level;
1945 int lowest_unlock = 1;
1946 u8 lowest_level = 0;
1947
1948 lowest_level = p->lowest_level;
1949 WARN_ON(p->nodes[0] != NULL);
1950
1951 if (p->search_commit_root) {
1952 BUG_ON(time_seq);
1953 return btrfs_search_slot(NULL, root, key, p, 0, 0);
1954 }
1955
1956again:
1957 b = btrfs_get_old_root(root, time_seq);
1958 if (!b) {
1959 ret = -EIO;
1960 goto done;
1961 }
1962 level = btrfs_header_level(b);
1963 p->locks[level] = BTRFS_READ_LOCK;
1964
1965 while (b) {
1966 int dec = 0;
1967
1968 level = btrfs_header_level(b);
1969 p->nodes[level] = b;
1970
1971 /*
1972 * we have a lock on b and as long as we aren't changing
1973 * the tree, there is no way to for the items in b to change.
1974 * It is safe to drop the lock on our parent before we
1975 * go through the expensive btree search on b.
1976 */
1977 btrfs_unlock_up_safe(p, level + 1);
1978
1979 ret = btrfs_bin_search(b, key, &slot);
1980 if (ret < 0)
1981 goto done;
1982
1983 if (level == 0) {
1984 p->slots[level] = slot;
1985 unlock_up(p, level, lowest_unlock, 0, NULL);
1986 goto done;
1987 }
1988
1989 if (ret && slot > 0) {
1990 dec = 1;
1991 slot--;
1992 }
1993 p->slots[level] = slot;
1994 unlock_up(p, level, lowest_unlock, 0, NULL);
1995
1996 if (level == lowest_level) {
1997 if (dec)
1998 p->slots[level]++;
1999 goto done;
2000 }
2001
2002 err = read_block_for_search(root, p, &b, level, slot, key);
2003 if (err == -EAGAIN)
2004 goto again;
2005 if (err) {
2006 ret = err;
2007 goto done;
2008 }
2009
2010 level = btrfs_header_level(b);
2011 btrfs_tree_read_lock(b);
2012 b = btrfs_tree_mod_log_rewind(fs_info, p, b, time_seq);
2013 if (!b) {
2014 ret = -ENOMEM;
2015 goto done;
2016 }
2017 p->locks[level] = BTRFS_READ_LOCK;
2018 p->nodes[level] = b;
2019 }
2020 ret = 1;
2021done:
2022 if (ret < 0)
2023 btrfs_release_path(p);
2024
2025 return ret;
2026}
2027
2028/*
2029 * helper to use instead of search slot if no exact match is needed but
2030 * instead the next or previous item should be returned.
2031 * When find_higher is true, the next higher item is returned, the next lower
2032 * otherwise.
2033 * When return_any and find_higher are both true, and no higher item is found,
2034 * return the next lower instead.
2035 * When return_any is true and find_higher is false, and no lower item is found,
2036 * return the next higher instead.
2037 * It returns 0 if any item is found, 1 if none is found (tree empty), and
2038 * < 0 on error
2039 */
2040int btrfs_search_slot_for_read(struct btrfs_root *root,
2041 const struct btrfs_key *key,
2042 struct btrfs_path *p, int find_higher,
2043 int return_any)
2044{
2045 int ret;
2046 struct extent_buffer *leaf;
2047
2048again:
2049 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
2050 if (ret <= 0)
2051 return ret;
2052 /*
2053 * a return value of 1 means the path is at the position where the
2054 * item should be inserted. Normally this is the next bigger item,
2055 * but in case the previous item is the last in a leaf, path points
2056 * to the first free slot in the previous leaf, i.e. at an invalid
2057 * item.
2058 */
2059 leaf = p->nodes[0];
2060
2061 if (find_higher) {
2062 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
2063 ret = btrfs_next_leaf(root, p);
2064 if (ret <= 0)
2065 return ret;
2066 if (!return_any)
2067 return 1;
2068 /*
2069 * no higher item found, return the next
2070 * lower instead
2071 */
2072 return_any = 0;
2073 find_higher = 0;
2074 btrfs_release_path(p);
2075 goto again;
2076 }
2077 } else {
2078 if (p->slots[0] == 0) {
2079 ret = btrfs_prev_leaf(root, p);
2080 if (ret < 0)
2081 return ret;
2082 if (!ret) {
2083 leaf = p->nodes[0];
2084 if (p->slots[0] == btrfs_header_nritems(leaf))
2085 p->slots[0]--;
2086 return 0;
2087 }
2088 if (!return_any)
2089 return 1;
2090 /*
2091 * no lower item found, return the next
2092 * higher instead
2093 */
2094 return_any = 0;
2095 find_higher = 1;
2096 btrfs_release_path(p);
2097 goto again;
2098 } else {
2099 --p->slots[0];
2100 }
2101 }
2102 return 0;
2103}
2104
2105/*
2106 * adjust the pointers going up the tree, starting at level
2107 * making sure the right key of each node is points to 'key'.
2108 * This is used after shifting pointers to the left, so it stops
2109 * fixing up pointers when a given leaf/node is not in slot 0 of the
2110 * higher levels
2111 *
2112 */
2113static void fixup_low_keys(struct btrfs_path *path,
2114 struct btrfs_disk_key *key, int level)
2115{
2116 int i;
2117 struct extent_buffer *t;
2118 int ret;
2119
2120 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2121 int tslot = path->slots[i];
2122
2123 if (!path->nodes[i])
2124 break;
2125 t = path->nodes[i];
2126 ret = btrfs_tree_mod_log_insert_key(t, tslot,
2127 BTRFS_MOD_LOG_KEY_REPLACE, GFP_ATOMIC);
2128 BUG_ON(ret < 0);
2129 btrfs_set_node_key(t, key, tslot);
2130 btrfs_mark_buffer_dirty(path->nodes[i]);
2131 if (tslot != 0)
2132 break;
2133 }
2134}
2135
2136/*
2137 * update item key.
2138 *
2139 * This function isn't completely safe. It's the caller's responsibility
2140 * that the new key won't break the order
2141 */
2142void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
2143 struct btrfs_path *path,
2144 const struct btrfs_key *new_key)
2145{
2146 struct btrfs_disk_key disk_key;
2147 struct extent_buffer *eb;
2148 int slot;
2149
2150 eb = path->nodes[0];
2151 slot = path->slots[0];
2152 if (slot > 0) {
2153 btrfs_item_key(eb, &disk_key, slot - 1);
2154 if (unlikely(comp_keys(&disk_key, new_key) >= 0)) {
2155 btrfs_crit(fs_info,
2156 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2157 slot, btrfs_disk_key_objectid(&disk_key),
2158 btrfs_disk_key_type(&disk_key),
2159 btrfs_disk_key_offset(&disk_key),
2160 new_key->objectid, new_key->type,
2161 new_key->offset);
2162 btrfs_print_leaf(eb);
2163 BUG();
2164 }
2165 }
2166 if (slot < btrfs_header_nritems(eb) - 1) {
2167 btrfs_item_key(eb, &disk_key, slot + 1);
2168 if (unlikely(comp_keys(&disk_key, new_key) <= 0)) {
2169 btrfs_crit(fs_info,
2170 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2171 slot, btrfs_disk_key_objectid(&disk_key),
2172 btrfs_disk_key_type(&disk_key),
2173 btrfs_disk_key_offset(&disk_key),
2174 new_key->objectid, new_key->type,
2175 new_key->offset);
2176 btrfs_print_leaf(eb);
2177 BUG();
2178 }
2179 }
2180
2181 btrfs_cpu_key_to_disk(&disk_key, new_key);
2182 btrfs_set_item_key(eb, &disk_key, slot);
2183 btrfs_mark_buffer_dirty(eb);
2184 if (slot == 0)
2185 fixup_low_keys(path, &disk_key, 1);
2186}
2187
2188/*
2189 * Check key order of two sibling extent buffers.
2190 *
2191 * Return true if something is wrong.
2192 * Return false if everything is fine.
2193 *
2194 * Tree-checker only works inside one tree block, thus the following
2195 * corruption can not be detected by tree-checker:
2196 *
2197 * Leaf @left | Leaf @right
2198 * --------------------------------------------------------------
2199 * | 1 | 2 | 3 | 4 | 5 | f6 | | 7 | 8 |
2200 *
2201 * Key f6 in leaf @left itself is valid, but not valid when the next
2202 * key in leaf @right is 7.
2203 * This can only be checked at tree block merge time.
2204 * And since tree checker has ensured all key order in each tree block
2205 * is correct, we only need to bother the last key of @left and the first
2206 * key of @right.
2207 */
2208static bool check_sibling_keys(struct extent_buffer *left,
2209 struct extent_buffer *right)
2210{
2211 struct btrfs_key left_last;
2212 struct btrfs_key right_first;
2213 int level = btrfs_header_level(left);
2214 int nr_left = btrfs_header_nritems(left);
2215 int nr_right = btrfs_header_nritems(right);
2216
2217 /* No key to check in one of the tree blocks */
2218 if (!nr_left || !nr_right)
2219 return false;
2220
2221 if (level) {
2222 btrfs_node_key_to_cpu(left, &left_last, nr_left - 1);
2223 btrfs_node_key_to_cpu(right, &right_first, 0);
2224 } else {
2225 btrfs_item_key_to_cpu(left, &left_last, nr_left - 1);
2226 btrfs_item_key_to_cpu(right, &right_first, 0);
2227 }
2228
2229 if (btrfs_comp_cpu_keys(&left_last, &right_first) >= 0) {
2230 btrfs_crit(left->fs_info,
2231"bad key order, sibling blocks, left last (%llu %u %llu) right first (%llu %u %llu)",
2232 left_last.objectid, left_last.type,
2233 left_last.offset, right_first.objectid,
2234 right_first.type, right_first.offset);
2235 return true;
2236 }
2237 return false;
2238}
2239
2240/*
2241 * try to push data from one node into the next node left in the
2242 * tree.
2243 *
2244 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2245 * error, and > 0 if there was no room in the left hand block.
2246 */
2247static int push_node_left(struct btrfs_trans_handle *trans,
2248 struct extent_buffer *dst,
2249 struct extent_buffer *src, int empty)
2250{
2251 struct btrfs_fs_info *fs_info = trans->fs_info;
2252 int push_items = 0;
2253 int src_nritems;
2254 int dst_nritems;
2255 int ret = 0;
2256
2257 src_nritems = btrfs_header_nritems(src);
2258 dst_nritems = btrfs_header_nritems(dst);
2259 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2260 WARN_ON(btrfs_header_generation(src) != trans->transid);
2261 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2262
2263 if (!empty && src_nritems <= 8)
2264 return 1;
2265
2266 if (push_items <= 0)
2267 return 1;
2268
2269 if (empty) {
2270 push_items = min(src_nritems, push_items);
2271 if (push_items < src_nritems) {
2272 /* leave at least 8 pointers in the node if
2273 * we aren't going to empty it
2274 */
2275 if (src_nritems - push_items < 8) {
2276 if (push_items <= 8)
2277 return 1;
2278 push_items -= 8;
2279 }
2280 }
2281 } else
2282 push_items = min(src_nritems - 8, push_items);
2283
2284 /* dst is the left eb, src is the middle eb */
2285 if (check_sibling_keys(dst, src)) {
2286 ret = -EUCLEAN;
2287 btrfs_abort_transaction(trans, ret);
2288 return ret;
2289 }
2290 ret = btrfs_tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
2291 if (ret) {
2292 btrfs_abort_transaction(trans, ret);
2293 return ret;
2294 }
2295 copy_extent_buffer(dst, src,
2296 btrfs_node_key_ptr_offset(dst_nritems),
2297 btrfs_node_key_ptr_offset(0),
2298 push_items * sizeof(struct btrfs_key_ptr));
2299
2300 if (push_items < src_nritems) {
2301 /*
2302 * Don't call btrfs_tree_mod_log_insert_move() here, key removal
2303 * was already fully logged by btrfs_tree_mod_log_eb_copy() above.
2304 */
2305 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
2306 btrfs_node_key_ptr_offset(push_items),
2307 (src_nritems - push_items) *
2308 sizeof(struct btrfs_key_ptr));
2309 }
2310 btrfs_set_header_nritems(src, src_nritems - push_items);
2311 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2312 btrfs_mark_buffer_dirty(src);
2313 btrfs_mark_buffer_dirty(dst);
2314
2315 return ret;
2316}
2317
2318/*
2319 * try to push data from one node into the next node right in the
2320 * tree.
2321 *
2322 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
2323 * error, and > 0 if there was no room in the right hand block.
2324 *
2325 * this will only push up to 1/2 the contents of the left node over
2326 */
2327static int balance_node_right(struct btrfs_trans_handle *trans,
2328 struct extent_buffer *dst,
2329 struct extent_buffer *src)
2330{
2331 struct btrfs_fs_info *fs_info = trans->fs_info;
2332 int push_items = 0;
2333 int max_push;
2334 int src_nritems;
2335 int dst_nritems;
2336 int ret = 0;
2337
2338 WARN_ON(btrfs_header_generation(src) != trans->transid);
2339 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2340
2341 src_nritems = btrfs_header_nritems(src);
2342 dst_nritems = btrfs_header_nritems(dst);
2343 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2344 if (push_items <= 0)
2345 return 1;
2346
2347 if (src_nritems < 4)
2348 return 1;
2349
2350 max_push = src_nritems / 2 + 1;
2351 /* don't try to empty the node */
2352 if (max_push >= src_nritems)
2353 return 1;
2354
2355 if (max_push < push_items)
2356 push_items = max_push;
2357
2358 /* dst is the right eb, src is the middle eb */
2359 if (check_sibling_keys(src, dst)) {
2360 ret = -EUCLEAN;
2361 btrfs_abort_transaction(trans, ret);
2362 return ret;
2363 }
2364 ret = btrfs_tree_mod_log_insert_move(dst, push_items, 0, dst_nritems);
2365 BUG_ON(ret < 0);
2366 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
2367 btrfs_node_key_ptr_offset(0),
2368 (dst_nritems) *
2369 sizeof(struct btrfs_key_ptr));
2370
2371 ret = btrfs_tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
2372 push_items);
2373 if (ret) {
2374 btrfs_abort_transaction(trans, ret);
2375 return ret;
2376 }
2377 copy_extent_buffer(dst, src,
2378 btrfs_node_key_ptr_offset(0),
2379 btrfs_node_key_ptr_offset(src_nritems - push_items),
2380 push_items * sizeof(struct btrfs_key_ptr));
2381
2382 btrfs_set_header_nritems(src, src_nritems - push_items);
2383 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2384
2385 btrfs_mark_buffer_dirty(src);
2386 btrfs_mark_buffer_dirty(dst);
2387
2388 return ret;
2389}
2390
2391/*
2392 * helper function to insert a new root level in the tree.
2393 * A new node is allocated, and a single item is inserted to
2394 * point to the existing root
2395 *
2396 * returns zero on success or < 0 on failure.
2397 */
2398static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2399 struct btrfs_root *root,
2400 struct btrfs_path *path, int level)
2401{
2402 struct btrfs_fs_info *fs_info = root->fs_info;
2403 u64 lower_gen;
2404 struct extent_buffer *lower;
2405 struct extent_buffer *c;
2406 struct extent_buffer *old;
2407 struct btrfs_disk_key lower_key;
2408 int ret;
2409
2410 BUG_ON(path->nodes[level]);
2411 BUG_ON(path->nodes[level-1] != root->node);
2412
2413 lower = path->nodes[level-1];
2414 if (level == 1)
2415 btrfs_item_key(lower, &lower_key, 0);
2416 else
2417 btrfs_node_key(lower, &lower_key, 0);
2418
2419 c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
2420 &lower_key, level, root->node->start, 0,
2421 BTRFS_NESTING_NEW_ROOT);
2422 if (IS_ERR(c))
2423 return PTR_ERR(c);
2424
2425 root_add_used(root, fs_info->nodesize);
2426
2427 btrfs_set_header_nritems(c, 1);
2428 btrfs_set_node_key(c, &lower_key, 0);
2429 btrfs_set_node_blockptr(c, 0, lower->start);
2430 lower_gen = btrfs_header_generation(lower);
2431 WARN_ON(lower_gen != trans->transid);
2432
2433 btrfs_set_node_ptr_generation(c, 0, lower_gen);
2434
2435 btrfs_mark_buffer_dirty(c);
2436
2437 old = root->node;
2438 ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
2439 BUG_ON(ret < 0);
2440 rcu_assign_pointer(root->node, c);
2441
2442 /* the super has an extra ref to root->node */
2443 free_extent_buffer(old);
2444
2445 add_root_to_dirty_list(root);
2446 atomic_inc(&c->refs);
2447 path->nodes[level] = c;
2448 path->locks[level] = BTRFS_WRITE_LOCK;
2449 path->slots[level] = 0;
2450 return 0;
2451}
2452
2453/*
2454 * worker function to insert a single pointer in a node.
2455 * the node should have enough room for the pointer already
2456 *
2457 * slot and level indicate where you want the key to go, and
2458 * blocknr is the block the key points to.
2459 */
2460static void insert_ptr(struct btrfs_trans_handle *trans,
2461 struct btrfs_path *path,
2462 struct btrfs_disk_key *key, u64 bytenr,
2463 int slot, int level)
2464{
2465 struct extent_buffer *lower;
2466 int nritems;
2467 int ret;
2468
2469 BUG_ON(!path->nodes[level]);
2470 btrfs_assert_tree_locked(path->nodes[level]);
2471 lower = path->nodes[level];
2472 nritems = btrfs_header_nritems(lower);
2473 BUG_ON(slot > nritems);
2474 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
2475 if (slot != nritems) {
2476 if (level) {
2477 ret = btrfs_tree_mod_log_insert_move(lower, slot + 1,
2478 slot, nritems - slot);
2479 BUG_ON(ret < 0);
2480 }
2481 memmove_extent_buffer(lower,
2482 btrfs_node_key_ptr_offset(slot + 1),
2483 btrfs_node_key_ptr_offset(slot),
2484 (nritems - slot) * sizeof(struct btrfs_key_ptr));
2485 }
2486 if (level) {
2487 ret = btrfs_tree_mod_log_insert_key(lower, slot,
2488 BTRFS_MOD_LOG_KEY_ADD, GFP_NOFS);
2489 BUG_ON(ret < 0);
2490 }
2491 btrfs_set_node_key(lower, key, slot);
2492 btrfs_set_node_blockptr(lower, slot, bytenr);
2493 WARN_ON(trans->transid == 0);
2494 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
2495 btrfs_set_header_nritems(lower, nritems + 1);
2496 btrfs_mark_buffer_dirty(lower);
2497}
2498
2499/*
2500 * split the node at the specified level in path in two.
2501 * The path is corrected to point to the appropriate node after the split
2502 *
2503 * Before splitting this tries to make some room in the node by pushing
2504 * left and right, if either one works, it returns right away.
2505 *
2506 * returns 0 on success and < 0 on failure
2507 */
2508static noinline int split_node(struct btrfs_trans_handle *trans,
2509 struct btrfs_root *root,
2510 struct btrfs_path *path, int level)
2511{
2512 struct btrfs_fs_info *fs_info = root->fs_info;
2513 struct extent_buffer *c;
2514 struct extent_buffer *split;
2515 struct btrfs_disk_key disk_key;
2516 int mid;
2517 int ret;
2518 u32 c_nritems;
2519
2520 c = path->nodes[level];
2521 WARN_ON(btrfs_header_generation(c) != trans->transid);
2522 if (c == root->node) {
2523 /*
2524 * trying to split the root, lets make a new one
2525 *
2526 * tree mod log: We don't log_removal old root in
2527 * insert_new_root, because that root buffer will be kept as a
2528 * normal node. We are going to log removal of half of the
2529 * elements below with btrfs_tree_mod_log_eb_copy(). We're
2530 * holding a tree lock on the buffer, which is why we cannot
2531 * race with other tree_mod_log users.
2532 */
2533 ret = insert_new_root(trans, root, path, level + 1);
2534 if (ret)
2535 return ret;
2536 } else {
2537 ret = push_nodes_for_insert(trans, root, path, level);
2538 c = path->nodes[level];
2539 if (!ret && btrfs_header_nritems(c) <
2540 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
2541 return 0;
2542 if (ret < 0)
2543 return ret;
2544 }
2545
2546 c_nritems = btrfs_header_nritems(c);
2547 mid = (c_nritems + 1) / 2;
2548 btrfs_node_key(c, &disk_key, mid);
2549
2550 split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
2551 &disk_key, level, c->start, 0,
2552 BTRFS_NESTING_SPLIT);
2553 if (IS_ERR(split))
2554 return PTR_ERR(split);
2555
2556 root_add_used(root, fs_info->nodesize);
2557 ASSERT(btrfs_header_level(c) == level);
2558
2559 ret = btrfs_tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
2560 if (ret) {
2561 btrfs_abort_transaction(trans, ret);
2562 return ret;
2563 }
2564 copy_extent_buffer(split, c,
2565 btrfs_node_key_ptr_offset(0),
2566 btrfs_node_key_ptr_offset(mid),
2567 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
2568 btrfs_set_header_nritems(split, c_nritems - mid);
2569 btrfs_set_header_nritems(c, mid);
2570
2571 btrfs_mark_buffer_dirty(c);
2572 btrfs_mark_buffer_dirty(split);
2573
2574 insert_ptr(trans, path, &disk_key, split->start,
2575 path->slots[level + 1] + 1, level + 1);
2576
2577 if (path->slots[level] >= mid) {
2578 path->slots[level] -= mid;
2579 btrfs_tree_unlock(c);
2580 free_extent_buffer(c);
2581 path->nodes[level] = split;
2582 path->slots[level + 1] += 1;
2583 } else {
2584 btrfs_tree_unlock(split);
2585 free_extent_buffer(split);
2586 }
2587 return 0;
2588}
2589
2590/*
2591 * how many bytes are required to store the items in a leaf. start
2592 * and nr indicate which items in the leaf to check. This totals up the
2593 * space used both by the item structs and the item data
2594 */
2595static int leaf_space_used(struct extent_buffer *l, int start, int nr)
2596{
2597 struct btrfs_item *start_item;
2598 struct btrfs_item *end_item;
2599 int data_len;
2600 int nritems = btrfs_header_nritems(l);
2601 int end = min(nritems, start + nr) - 1;
2602
2603 if (!nr)
2604 return 0;
2605 start_item = btrfs_item_nr(start);
2606 end_item = btrfs_item_nr(end);
2607 data_len = btrfs_item_offset(l, start_item) +
2608 btrfs_item_size(l, start_item);
2609 data_len = data_len - btrfs_item_offset(l, end_item);
2610 data_len += sizeof(struct btrfs_item) * nr;
2611 WARN_ON(data_len < 0);
2612 return data_len;
2613}
2614
2615/*
2616 * The space between the end of the leaf items and
2617 * the start of the leaf data. IOW, how much room
2618 * the leaf has left for both items and data
2619 */
2620noinline int btrfs_leaf_free_space(struct extent_buffer *leaf)
2621{
2622 struct btrfs_fs_info *fs_info = leaf->fs_info;
2623 int nritems = btrfs_header_nritems(leaf);
2624 int ret;
2625
2626 ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
2627 if (ret < 0) {
2628 btrfs_crit(fs_info,
2629 "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
2630 ret,
2631 (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
2632 leaf_space_used(leaf, 0, nritems), nritems);
2633 }
2634 return ret;
2635}
2636
2637/*
2638 * min slot controls the lowest index we're willing to push to the
2639 * right. We'll push up to and including min_slot, but no lower
2640 */
2641static noinline int __push_leaf_right(struct btrfs_path *path,
2642 int data_size, int empty,
2643 struct extent_buffer *right,
2644 int free_space, u32 left_nritems,
2645 u32 min_slot)
2646{
2647 struct btrfs_fs_info *fs_info = right->fs_info;
2648 struct extent_buffer *left = path->nodes[0];
2649 struct extent_buffer *upper = path->nodes[1];
2650 struct btrfs_map_token token;
2651 struct btrfs_disk_key disk_key;
2652 int slot;
2653 u32 i;
2654 int push_space = 0;
2655 int push_items = 0;
2656 struct btrfs_item *item;
2657 u32 nr;
2658 u32 right_nritems;
2659 u32 data_end;
2660 u32 this_item_size;
2661
2662 if (empty)
2663 nr = 0;
2664 else
2665 nr = max_t(u32, 1, min_slot);
2666
2667 if (path->slots[0] >= left_nritems)
2668 push_space += data_size;
2669
2670 slot = path->slots[1];
2671 i = left_nritems - 1;
2672 while (i >= nr) {
2673 item = btrfs_item_nr(i);
2674
2675 if (!empty && push_items > 0) {
2676 if (path->slots[0] > i)
2677 break;
2678 if (path->slots[0] == i) {
2679 int space = btrfs_leaf_free_space(left);
2680
2681 if (space + push_space * 2 > free_space)
2682 break;
2683 }
2684 }
2685
2686 if (path->slots[0] == i)
2687 push_space += data_size;
2688
2689 this_item_size = btrfs_item_size(left, item);
2690 if (this_item_size + sizeof(*item) + push_space > free_space)
2691 break;
2692
2693 push_items++;
2694 push_space += this_item_size + sizeof(*item);
2695 if (i == 0)
2696 break;
2697 i--;
2698 }
2699
2700 if (push_items == 0)
2701 goto out_unlock;
2702
2703 WARN_ON(!empty && push_items == left_nritems);
2704
2705 /* push left to right */
2706 right_nritems = btrfs_header_nritems(right);
2707
2708 push_space = btrfs_item_end_nr(left, left_nritems - push_items);
2709 push_space -= leaf_data_end(left);
2710
2711 /* make room in the right data area */
2712 data_end = leaf_data_end(right);
2713 memmove_extent_buffer(right,
2714 BTRFS_LEAF_DATA_OFFSET + data_end - push_space,
2715 BTRFS_LEAF_DATA_OFFSET + data_end,
2716 BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
2717
2718 /* copy from the left data area */
2719 copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET +
2720 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
2721 BTRFS_LEAF_DATA_OFFSET + leaf_data_end(left),
2722 push_space);
2723
2724 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
2725 btrfs_item_nr_offset(0),
2726 right_nritems * sizeof(struct btrfs_item));
2727
2728 /* copy the items from left to right */
2729 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
2730 btrfs_item_nr_offset(left_nritems - push_items),
2731 push_items * sizeof(struct btrfs_item));
2732
2733 /* update the item pointers */
2734 btrfs_init_map_token(&token, right);
2735 right_nritems += push_items;
2736 btrfs_set_header_nritems(right, right_nritems);
2737 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
2738 for (i = 0; i < right_nritems; i++) {
2739 item = btrfs_item_nr(i);
2740 push_space -= btrfs_token_item_size(&token, item);
2741 btrfs_set_token_item_offset(&token, item, push_space);
2742 }
2743
2744 left_nritems -= push_items;
2745 btrfs_set_header_nritems(left, left_nritems);
2746
2747 if (left_nritems)
2748 btrfs_mark_buffer_dirty(left);
2749 else
2750 btrfs_clean_tree_block(left);
2751
2752 btrfs_mark_buffer_dirty(right);
2753
2754 btrfs_item_key(right, &disk_key, 0);
2755 btrfs_set_node_key(upper, &disk_key, slot + 1);
2756 btrfs_mark_buffer_dirty(upper);
2757
2758 /* then fixup the leaf pointer in the path */
2759 if (path->slots[0] >= left_nritems) {
2760 path->slots[0] -= left_nritems;
2761 if (btrfs_header_nritems(path->nodes[0]) == 0)
2762 btrfs_clean_tree_block(path->nodes[0]);
2763 btrfs_tree_unlock(path->nodes[0]);
2764 free_extent_buffer(path->nodes[0]);
2765 path->nodes[0] = right;
2766 path->slots[1] += 1;
2767 } else {
2768 btrfs_tree_unlock(right);
2769 free_extent_buffer(right);
2770 }
2771 return 0;
2772
2773out_unlock:
2774 btrfs_tree_unlock(right);
2775 free_extent_buffer(right);
2776 return 1;
2777}
2778
2779/*
2780 * push some data in the path leaf to the right, trying to free up at
2781 * least data_size bytes. returns zero if the push worked, nonzero otherwise
2782 *
2783 * returns 1 if the push failed because the other node didn't have enough
2784 * room, 0 if everything worked out and < 0 if there were major errors.
2785 *
2786 * this will push starting from min_slot to the end of the leaf. It won't
2787 * push any slot lower than min_slot
2788 */
2789static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
2790 *root, struct btrfs_path *path,
2791 int min_data_size, int data_size,
2792 int empty, u32 min_slot)
2793{
2794 struct extent_buffer *left = path->nodes[0];
2795 struct extent_buffer *right;
2796 struct extent_buffer *upper;
2797 int slot;
2798 int free_space;
2799 u32 left_nritems;
2800 int ret;
2801
2802 if (!path->nodes[1])
2803 return 1;
2804
2805 slot = path->slots[1];
2806 upper = path->nodes[1];
2807 if (slot >= btrfs_header_nritems(upper) - 1)
2808 return 1;
2809
2810 btrfs_assert_tree_locked(path->nodes[1]);
2811
2812 right = btrfs_read_node_slot(upper, slot + 1);
2813 /*
2814 * slot + 1 is not valid or we fail to read the right node,
2815 * no big deal, just return.
2816 */
2817 if (IS_ERR(right))
2818 return 1;
2819
2820 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
2821
2822 free_space = btrfs_leaf_free_space(right);
2823 if (free_space < data_size)
2824 goto out_unlock;
2825
2826 /* cow and double check */
2827 ret = btrfs_cow_block(trans, root, right, upper,
2828 slot + 1, &right, BTRFS_NESTING_RIGHT_COW);
2829 if (ret)
2830 goto out_unlock;
2831
2832 free_space = btrfs_leaf_free_space(right);
2833 if (free_space < data_size)
2834 goto out_unlock;
2835
2836 left_nritems = btrfs_header_nritems(left);
2837 if (left_nritems == 0)
2838 goto out_unlock;
2839
2840 if (check_sibling_keys(left, right)) {
2841 ret = -EUCLEAN;
2842 btrfs_tree_unlock(right);
2843 free_extent_buffer(right);
2844 return ret;
2845 }
2846 if (path->slots[0] == left_nritems && !empty) {
2847 /* Key greater than all keys in the leaf, right neighbor has
2848 * enough room for it and we're not emptying our leaf to delete
2849 * it, therefore use right neighbor to insert the new item and
2850 * no need to touch/dirty our left leaf. */
2851 btrfs_tree_unlock(left);
2852 free_extent_buffer(left);
2853 path->nodes[0] = right;
2854 path->slots[0] = 0;
2855 path->slots[1]++;
2856 return 0;
2857 }
2858
2859 return __push_leaf_right(path, min_data_size, empty,
2860 right, free_space, left_nritems, min_slot);
2861out_unlock:
2862 btrfs_tree_unlock(right);
2863 free_extent_buffer(right);
2864 return 1;
2865}
2866
2867/*
2868 * push some data in the path leaf to the left, trying to free up at
2869 * least data_size bytes. returns zero if the push worked, nonzero otherwise
2870 *
2871 * max_slot can put a limit on how far into the leaf we'll push items. The
2872 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
2873 * items
2874 */
2875static noinline int __push_leaf_left(struct btrfs_path *path, int data_size,
2876 int empty, struct extent_buffer *left,
2877 int free_space, u32 right_nritems,
2878 u32 max_slot)
2879{
2880 struct btrfs_fs_info *fs_info = left->fs_info;
2881 struct btrfs_disk_key disk_key;
2882 struct extent_buffer *right = path->nodes[0];
2883 int i;
2884 int push_space = 0;
2885 int push_items = 0;
2886 struct btrfs_item *item;
2887 u32 old_left_nritems;
2888 u32 nr;
2889 int ret = 0;
2890 u32 this_item_size;
2891 u32 old_left_item_size;
2892 struct btrfs_map_token token;
2893
2894 if (empty)
2895 nr = min(right_nritems, max_slot);
2896 else
2897 nr = min(right_nritems - 1, max_slot);
2898
2899 for (i = 0; i < nr; i++) {
2900 item = btrfs_item_nr(i);
2901
2902 if (!empty && push_items > 0) {
2903 if (path->slots[0] < i)
2904 break;
2905 if (path->slots[0] == i) {
2906 int space = btrfs_leaf_free_space(right);
2907
2908 if (space + push_space * 2 > free_space)
2909 break;
2910 }
2911 }
2912
2913 if (path->slots[0] == i)
2914 push_space += data_size;
2915
2916 this_item_size = btrfs_item_size(right, item);
2917 if (this_item_size + sizeof(*item) + push_space > free_space)
2918 break;
2919
2920 push_items++;
2921 push_space += this_item_size + sizeof(*item);
2922 }
2923
2924 if (push_items == 0) {
2925 ret = 1;
2926 goto out;
2927 }
2928 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
2929
2930 /* push data from right to left */
2931 copy_extent_buffer(left, right,
2932 btrfs_item_nr_offset(btrfs_header_nritems(left)),
2933 btrfs_item_nr_offset(0),
2934 push_items * sizeof(struct btrfs_item));
2935
2936 push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
2937 btrfs_item_offset_nr(right, push_items - 1);
2938
2939 copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET +
2940 leaf_data_end(left) - push_space,
2941 BTRFS_LEAF_DATA_OFFSET +
2942 btrfs_item_offset_nr(right, push_items - 1),
2943 push_space);
2944 old_left_nritems = btrfs_header_nritems(left);
2945 BUG_ON(old_left_nritems <= 0);
2946
2947 btrfs_init_map_token(&token, left);
2948 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
2949 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
2950 u32 ioff;
2951
2952 item = btrfs_item_nr(i);
2953
2954 ioff = btrfs_token_item_offset(&token, item);
2955 btrfs_set_token_item_offset(&token, item,
2956 ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size));
2957 }
2958 btrfs_set_header_nritems(left, old_left_nritems + push_items);
2959
2960 /* fixup right node */
2961 if (push_items > right_nritems)
2962 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
2963 right_nritems);
2964
2965 if (push_items < right_nritems) {
2966 push_space = btrfs_item_offset_nr(right, push_items - 1) -
2967 leaf_data_end(right);
2968 memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET +
2969 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
2970 BTRFS_LEAF_DATA_OFFSET +
2971 leaf_data_end(right), push_space);
2972
2973 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
2974 btrfs_item_nr_offset(push_items),
2975 (btrfs_header_nritems(right) - push_items) *
2976 sizeof(struct btrfs_item));
2977 }
2978
2979 btrfs_init_map_token(&token, right);
2980 right_nritems -= push_items;
2981 btrfs_set_header_nritems(right, right_nritems);
2982 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
2983 for (i = 0; i < right_nritems; i++) {
2984 item = btrfs_item_nr(i);
2985
2986 push_space = push_space - btrfs_token_item_size(&token, item);
2987 btrfs_set_token_item_offset(&token, item, push_space);
2988 }
2989
2990 btrfs_mark_buffer_dirty(left);
2991 if (right_nritems)
2992 btrfs_mark_buffer_dirty(right);
2993 else
2994 btrfs_clean_tree_block(right);
2995
2996 btrfs_item_key(right, &disk_key, 0);
2997 fixup_low_keys(path, &disk_key, 1);
2998
2999 /* then fixup the leaf pointer in the path */
3000 if (path->slots[0] < push_items) {
3001 path->slots[0] += old_left_nritems;
3002 btrfs_tree_unlock(path->nodes[0]);
3003 free_extent_buffer(path->nodes[0]);
3004 path->nodes[0] = left;
3005 path->slots[1] -= 1;
3006 } else {
3007 btrfs_tree_unlock(left);
3008 free_extent_buffer(left);
3009 path->slots[0] -= push_items;
3010 }
3011 BUG_ON(path->slots[0] < 0);
3012 return ret;
3013out:
3014 btrfs_tree_unlock(left);
3015 free_extent_buffer(left);
3016 return ret;
3017}
3018
3019/*
3020 * push some data in the path leaf to the left, trying to free up at
3021 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3022 *
3023 * max_slot can put a limit on how far into the leaf we'll push items. The
3024 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3025 * items
3026 */
3027static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3028 *root, struct btrfs_path *path, int min_data_size,
3029 int data_size, int empty, u32 max_slot)
3030{
3031 struct extent_buffer *right = path->nodes[0];
3032 struct extent_buffer *left;
3033 int slot;
3034 int free_space;
3035 u32 right_nritems;
3036 int ret = 0;
3037
3038 slot = path->slots[1];
3039 if (slot == 0)
3040 return 1;
3041 if (!path->nodes[1])
3042 return 1;
3043
3044 right_nritems = btrfs_header_nritems(right);
3045 if (right_nritems == 0)
3046 return 1;
3047
3048 btrfs_assert_tree_locked(path->nodes[1]);
3049
3050 left = btrfs_read_node_slot(path->nodes[1], slot - 1);
3051 /*
3052 * slot - 1 is not valid or we fail to read the left node,
3053 * no big deal, just return.
3054 */
3055 if (IS_ERR(left))
3056 return 1;
3057
3058 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
3059
3060 free_space = btrfs_leaf_free_space(left);
3061 if (free_space < data_size) {
3062 ret = 1;
3063 goto out;
3064 }
3065
3066 /* cow and double check */
3067 ret = btrfs_cow_block(trans, root, left,
3068 path->nodes[1], slot - 1, &left,
3069 BTRFS_NESTING_LEFT_COW);
3070 if (ret) {
3071 /* we hit -ENOSPC, but it isn't fatal here */
3072 if (ret == -ENOSPC)
3073 ret = 1;
3074 goto out;
3075 }
3076
3077 free_space = btrfs_leaf_free_space(left);
3078 if (free_space < data_size) {
3079 ret = 1;
3080 goto out;
3081 }
3082
3083 if (check_sibling_keys(left, right)) {
3084 ret = -EUCLEAN;
3085 goto out;
3086 }
3087 return __push_leaf_left(path, min_data_size,
3088 empty, left, free_space, right_nritems,
3089 max_slot);
3090out:
3091 btrfs_tree_unlock(left);
3092 free_extent_buffer(left);
3093 return ret;
3094}
3095
3096/*
3097 * split the path's leaf in two, making sure there is at least data_size
3098 * available for the resulting leaf level of the path.
3099 */
3100static noinline void copy_for_split(struct btrfs_trans_handle *trans,
3101 struct btrfs_path *path,
3102 struct extent_buffer *l,
3103 struct extent_buffer *right,
3104 int slot, int mid, int nritems)
3105{
3106 struct btrfs_fs_info *fs_info = trans->fs_info;
3107 int data_copy_size;
3108 int rt_data_off;
3109 int i;
3110 struct btrfs_disk_key disk_key;
3111 struct btrfs_map_token token;
3112
3113 nritems = nritems - mid;
3114 btrfs_set_header_nritems(right, nritems);
3115 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(l);
3116
3117 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
3118 btrfs_item_nr_offset(mid),
3119 nritems * sizeof(struct btrfs_item));
3120
3121 copy_extent_buffer(right, l,
3122 BTRFS_LEAF_DATA_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) -
3123 data_copy_size, BTRFS_LEAF_DATA_OFFSET +
3124 leaf_data_end(l), data_copy_size);
3125
3126 rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_end_nr(l, mid);
3127
3128 btrfs_init_map_token(&token, right);
3129 for (i = 0; i < nritems; i++) {
3130 struct btrfs_item *item = btrfs_item_nr(i);
3131 u32 ioff;
3132
3133 ioff = btrfs_token_item_offset(&token, item);
3134 btrfs_set_token_item_offset(&token, item, ioff + rt_data_off);
3135 }
3136
3137 btrfs_set_header_nritems(l, mid);
3138 btrfs_item_key(right, &disk_key, 0);
3139 insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
3140
3141 btrfs_mark_buffer_dirty(right);
3142 btrfs_mark_buffer_dirty(l);
3143 BUG_ON(path->slots[0] != slot);
3144
3145 if (mid <= slot) {
3146 btrfs_tree_unlock(path->nodes[0]);
3147 free_extent_buffer(path->nodes[0]);
3148 path->nodes[0] = right;
3149 path->slots[0] -= mid;
3150 path->slots[1] += 1;
3151 } else {
3152 btrfs_tree_unlock(right);
3153 free_extent_buffer(right);
3154 }
3155
3156 BUG_ON(path->slots[0] < 0);
3157}
3158
3159/*
3160 * double splits happen when we need to insert a big item in the middle
3161 * of a leaf. A double split can leave us with 3 mostly empty leaves:
3162 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
3163 * A B C
3164 *
3165 * We avoid this by trying to push the items on either side of our target
3166 * into the adjacent leaves. If all goes well we can avoid the double split
3167 * completely.
3168 */
3169static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
3170 struct btrfs_root *root,
3171 struct btrfs_path *path,
3172 int data_size)
3173{
3174 int ret;
3175 int progress = 0;
3176 int slot;
3177 u32 nritems;
3178 int space_needed = data_size;
3179
3180 slot = path->slots[0];
3181 if (slot < btrfs_header_nritems(path->nodes[0]))
3182 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3183
3184 /*
3185 * try to push all the items after our slot into the
3186 * right leaf
3187 */
3188 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
3189 if (ret < 0)
3190 return ret;
3191
3192 if (ret == 0)
3193 progress++;
3194
3195 nritems = btrfs_header_nritems(path->nodes[0]);
3196 /*
3197 * our goal is to get our slot at the start or end of a leaf. If
3198 * we've done so we're done
3199 */
3200 if (path->slots[0] == 0 || path->slots[0] == nritems)
3201 return 0;
3202
3203 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3204 return 0;
3205
3206 /* try to push all the items before our slot into the next leaf */
3207 slot = path->slots[0];
3208 space_needed = data_size;
3209 if (slot > 0)
3210 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3211 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
3212 if (ret < 0)
3213 return ret;
3214
3215 if (ret == 0)
3216 progress++;
3217
3218 if (progress)
3219 return 0;
3220 return 1;
3221}
3222
3223/*
3224 * split the path's leaf in two, making sure there is at least data_size
3225 * available for the resulting leaf level of the path.
3226 *
3227 * returns 0 if all went well and < 0 on failure.
3228 */
3229static noinline int split_leaf(struct btrfs_trans_handle *trans,
3230 struct btrfs_root *root,
3231 const struct btrfs_key *ins_key,
3232 struct btrfs_path *path, int data_size,
3233 int extend)
3234{
3235 struct btrfs_disk_key disk_key;
3236 struct extent_buffer *l;
3237 u32 nritems;
3238 int mid;
3239 int slot;
3240 struct extent_buffer *right;
3241 struct btrfs_fs_info *fs_info = root->fs_info;
3242 int ret = 0;
3243 int wret;
3244 int split;
3245 int num_doubles = 0;
3246 int tried_avoid_double = 0;
3247
3248 l = path->nodes[0];
3249 slot = path->slots[0];
3250 if (extend && data_size + btrfs_item_size_nr(l, slot) +
3251 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
3252 return -EOVERFLOW;
3253
3254 /* first try to make some room by pushing left and right */
3255 if (data_size && path->nodes[1]) {
3256 int space_needed = data_size;
3257
3258 if (slot < btrfs_header_nritems(l))
3259 space_needed -= btrfs_leaf_free_space(l);
3260
3261 wret = push_leaf_right(trans, root, path, space_needed,
3262 space_needed, 0, 0);
3263 if (wret < 0)
3264 return wret;
3265 if (wret) {
3266 space_needed = data_size;
3267 if (slot > 0)
3268 space_needed -= btrfs_leaf_free_space(l);
3269 wret = push_leaf_left(trans, root, path, space_needed,
3270 space_needed, 0, (u32)-1);
3271 if (wret < 0)
3272 return wret;
3273 }
3274 l = path->nodes[0];
3275
3276 /* did the pushes work? */
3277 if (btrfs_leaf_free_space(l) >= data_size)
3278 return 0;
3279 }
3280
3281 if (!path->nodes[1]) {
3282 ret = insert_new_root(trans, root, path, 1);
3283 if (ret)
3284 return ret;
3285 }
3286again:
3287 split = 1;
3288 l = path->nodes[0];
3289 slot = path->slots[0];
3290 nritems = btrfs_header_nritems(l);
3291 mid = (nritems + 1) / 2;
3292
3293 if (mid <= slot) {
3294 if (nritems == 1 ||
3295 leaf_space_used(l, mid, nritems - mid) + data_size >
3296 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3297 if (slot >= nritems) {
3298 split = 0;
3299 } else {
3300 mid = slot;
3301 if (mid != nritems &&
3302 leaf_space_used(l, mid, nritems - mid) +
3303 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3304 if (data_size && !tried_avoid_double)
3305 goto push_for_double;
3306 split = 2;
3307 }
3308 }
3309 }
3310 } else {
3311 if (leaf_space_used(l, 0, mid) + data_size >
3312 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3313 if (!extend && data_size && slot == 0) {
3314 split = 0;
3315 } else if ((extend || !data_size) && slot == 0) {
3316 mid = 1;
3317 } else {
3318 mid = slot;
3319 if (mid != nritems &&
3320 leaf_space_used(l, mid, nritems - mid) +
3321 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3322 if (data_size && !tried_avoid_double)
3323 goto push_for_double;
3324 split = 2;
3325 }
3326 }
3327 }
3328 }
3329
3330 if (split == 0)
3331 btrfs_cpu_key_to_disk(&disk_key, ins_key);
3332 else
3333 btrfs_item_key(l, &disk_key, mid);
3334
3335 /*
3336 * We have to about BTRFS_NESTING_NEW_ROOT here if we've done a double
3337 * split, because we're only allowed to have MAX_LOCKDEP_SUBCLASSES
3338 * subclasses, which is 8 at the time of this patch, and we've maxed it
3339 * out. In the future we could add a
3340 * BTRFS_NESTING_SPLIT_THE_SPLITTENING if we need to, but for now just
3341 * use BTRFS_NESTING_NEW_ROOT.
3342 */
3343 right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
3344 &disk_key, 0, l->start, 0,
3345 num_doubles ? BTRFS_NESTING_NEW_ROOT :
3346 BTRFS_NESTING_SPLIT);
3347 if (IS_ERR(right))
3348 return PTR_ERR(right);
3349
3350 root_add_used(root, fs_info->nodesize);
3351
3352 if (split == 0) {
3353 if (mid <= slot) {
3354 btrfs_set_header_nritems(right, 0);
3355 insert_ptr(trans, path, &disk_key,
3356 right->start, path->slots[1] + 1, 1);
3357 btrfs_tree_unlock(path->nodes[0]);
3358 free_extent_buffer(path->nodes[0]);
3359 path->nodes[0] = right;
3360 path->slots[0] = 0;
3361 path->slots[1] += 1;
3362 } else {
3363 btrfs_set_header_nritems(right, 0);
3364 insert_ptr(trans, path, &disk_key,
3365 right->start, path->slots[1], 1);
3366 btrfs_tree_unlock(path->nodes[0]);
3367 free_extent_buffer(path->nodes[0]);
3368 path->nodes[0] = right;
3369 path->slots[0] = 0;
3370 if (path->slots[1] == 0)
3371 fixup_low_keys(path, &disk_key, 1);
3372 }
3373 /*
3374 * We create a new leaf 'right' for the required ins_len and
3375 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
3376 * the content of ins_len to 'right'.
3377 */
3378 return ret;
3379 }
3380
3381 copy_for_split(trans, path, l, right, slot, mid, nritems);
3382
3383 if (split == 2) {
3384 BUG_ON(num_doubles != 0);
3385 num_doubles++;
3386 goto again;
3387 }
3388
3389 return 0;
3390
3391push_for_double:
3392 push_for_double_split(trans, root, path, data_size);
3393 tried_avoid_double = 1;
3394 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3395 return 0;
3396 goto again;
3397}
3398
3399static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3400 struct btrfs_root *root,
3401 struct btrfs_path *path, int ins_len)
3402{
3403 struct btrfs_key key;
3404 struct extent_buffer *leaf;
3405 struct btrfs_file_extent_item *fi;
3406 u64 extent_len = 0;
3407 u32 item_size;
3408 int ret;
3409
3410 leaf = path->nodes[0];
3411 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3412
3413 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3414 key.type != BTRFS_EXTENT_CSUM_KEY);
3415
3416 if (btrfs_leaf_free_space(leaf) >= ins_len)
3417 return 0;
3418
3419 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3420 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3421 fi = btrfs_item_ptr(leaf, path->slots[0],
3422 struct btrfs_file_extent_item);
3423 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3424 }
3425 btrfs_release_path(path);
3426
3427 path->keep_locks = 1;
3428 path->search_for_split = 1;
3429 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3430 path->search_for_split = 0;
3431 if (ret > 0)
3432 ret = -EAGAIN;
3433 if (ret < 0)
3434 goto err;
3435
3436 ret = -EAGAIN;
3437 leaf = path->nodes[0];
3438 /* if our item isn't there, return now */
3439 if (item_size != btrfs_item_size_nr(leaf, path->slots[0]))
3440 goto err;
3441
3442 /* the leaf has changed, it now has room. return now */
3443 if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
3444 goto err;
3445
3446 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3447 fi = btrfs_item_ptr(leaf, path->slots[0],
3448 struct btrfs_file_extent_item);
3449 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3450 goto err;
3451 }
3452
3453 ret = split_leaf(trans, root, &key, path, ins_len, 1);
3454 if (ret)
3455 goto err;
3456
3457 path->keep_locks = 0;
3458 btrfs_unlock_up_safe(path, 1);
3459 return 0;
3460err:
3461 path->keep_locks = 0;
3462 return ret;
3463}
3464
3465static noinline int split_item(struct btrfs_path *path,
3466 const struct btrfs_key *new_key,
3467 unsigned long split_offset)
3468{
3469 struct extent_buffer *leaf;
3470 struct btrfs_item *item;
3471 struct btrfs_item *new_item;
3472 int slot;
3473 char *buf;
3474 u32 nritems;
3475 u32 item_size;
3476 u32 orig_offset;
3477 struct btrfs_disk_key disk_key;
3478
3479 leaf = path->nodes[0];
3480 BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));
3481
3482 item = btrfs_item_nr(path->slots[0]);
3483 orig_offset = btrfs_item_offset(leaf, item);
3484 item_size = btrfs_item_size(leaf, item);
3485
3486 buf = kmalloc(item_size, GFP_NOFS);
3487 if (!buf)
3488 return -ENOMEM;
3489
3490 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3491 path->slots[0]), item_size);
3492
3493 slot = path->slots[0] + 1;
3494 nritems = btrfs_header_nritems(leaf);
3495 if (slot != nritems) {
3496 /* shift the items */
3497 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
3498 btrfs_item_nr_offset(slot),
3499 (nritems - slot) * sizeof(struct btrfs_item));
3500 }
3501
3502 btrfs_cpu_key_to_disk(&disk_key, new_key);
3503 btrfs_set_item_key(leaf, &disk_key, slot);
3504
3505 new_item = btrfs_item_nr(slot);
3506
3507 btrfs_set_item_offset(leaf, new_item, orig_offset);
3508 btrfs_set_item_size(leaf, new_item, item_size - split_offset);
3509
3510 btrfs_set_item_offset(leaf, item,
3511 orig_offset + item_size - split_offset);
3512 btrfs_set_item_size(leaf, item, split_offset);
3513
3514 btrfs_set_header_nritems(leaf, nritems + 1);
3515
3516 /* write the data for the start of the original item */
3517 write_extent_buffer(leaf, buf,
3518 btrfs_item_ptr_offset(leaf, path->slots[0]),
3519 split_offset);
3520
3521 /* write the data for the new item */
3522 write_extent_buffer(leaf, buf + split_offset,
3523 btrfs_item_ptr_offset(leaf, slot),
3524 item_size - split_offset);
3525 btrfs_mark_buffer_dirty(leaf);
3526
3527 BUG_ON(btrfs_leaf_free_space(leaf) < 0);
3528 kfree(buf);
3529 return 0;
3530}
3531
3532/*
3533 * This function splits a single item into two items,
3534 * giving 'new_key' to the new item and splitting the
3535 * old one at split_offset (from the start of the item).
3536 *
3537 * The path may be released by this operation. After
3538 * the split, the path is pointing to the old item. The
3539 * new item is going to be in the same node as the old one.
3540 *
3541 * Note, the item being split must be smaller enough to live alone on
3542 * a tree block with room for one extra struct btrfs_item
3543 *
3544 * This allows us to split the item in place, keeping a lock on the
3545 * leaf the entire time.
3546 */
3547int btrfs_split_item(struct btrfs_trans_handle *trans,
3548 struct btrfs_root *root,
3549 struct btrfs_path *path,
3550 const struct btrfs_key *new_key,
3551 unsigned long split_offset)
3552{
3553 int ret;
3554 ret = setup_leaf_for_split(trans, root, path,
3555 sizeof(struct btrfs_item));
3556 if (ret)
3557 return ret;
3558
3559 ret = split_item(path, new_key, split_offset);
3560 return ret;
3561}
3562
3563/*
3564 * This function duplicate a item, giving 'new_key' to the new item.
3565 * It guarantees both items live in the same tree leaf and the new item
3566 * is contiguous with the original item.
3567 *
3568 * This allows us to split file extent in place, keeping a lock on the
3569 * leaf the entire time.
3570 */
3571int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
3572 struct btrfs_root *root,
3573 struct btrfs_path *path,
3574 const struct btrfs_key *new_key)
3575{
3576 struct extent_buffer *leaf;
3577 int ret;
3578 u32 item_size;
3579
3580 leaf = path->nodes[0];
3581 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3582 ret = setup_leaf_for_split(trans, root, path,
3583 item_size + sizeof(struct btrfs_item));
3584 if (ret)
3585 return ret;
3586
3587 path->slots[0]++;
3588 setup_items_for_insert(root, path, new_key, &item_size, 1);
3589 leaf = path->nodes[0];
3590 memcpy_extent_buffer(leaf,
3591 btrfs_item_ptr_offset(leaf, path->slots[0]),
3592 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
3593 item_size);
3594 return 0;
3595}
3596
3597/*
3598 * make the item pointed to by the path smaller. new_size indicates
3599 * how small to make it, and from_end tells us if we just chop bytes
3600 * off the end of the item or if we shift the item to chop bytes off
3601 * the front.
3602 */
3603void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end)
3604{
3605 int slot;
3606 struct extent_buffer *leaf;
3607 struct btrfs_item *item;
3608 u32 nritems;
3609 unsigned int data_end;
3610 unsigned int old_data_start;
3611 unsigned int old_size;
3612 unsigned int size_diff;
3613 int i;
3614 struct btrfs_map_token token;
3615
3616 leaf = path->nodes[0];
3617 slot = path->slots[0];
3618
3619 old_size = btrfs_item_size_nr(leaf, slot);
3620 if (old_size == new_size)
3621 return;
3622
3623 nritems = btrfs_header_nritems(leaf);
3624 data_end = leaf_data_end(leaf);
3625
3626 old_data_start = btrfs_item_offset_nr(leaf, slot);
3627
3628 size_diff = old_size - new_size;
3629
3630 BUG_ON(slot < 0);
3631 BUG_ON(slot >= nritems);
3632
3633 /*
3634 * item0..itemN ... dataN.offset..dataN.size .. data0.size
3635 */
3636 /* first correct the data pointers */
3637 btrfs_init_map_token(&token, leaf);
3638 for (i = slot; i < nritems; i++) {
3639 u32 ioff;
3640 item = btrfs_item_nr(i);
3641
3642 ioff = btrfs_token_item_offset(&token, item);
3643 btrfs_set_token_item_offset(&token, item, ioff + size_diff);
3644 }
3645
3646 /* shift the data */
3647 if (from_end) {
3648 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3649 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
3650 data_end, old_data_start + new_size - data_end);
3651 } else {
3652 struct btrfs_disk_key disk_key;
3653 u64 offset;
3654
3655 btrfs_item_key(leaf, &disk_key, slot);
3656
3657 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
3658 unsigned long ptr;
3659 struct btrfs_file_extent_item *fi;
3660
3661 fi = btrfs_item_ptr(leaf, slot,
3662 struct btrfs_file_extent_item);
3663 fi = (struct btrfs_file_extent_item *)(
3664 (unsigned long)fi - size_diff);
3665
3666 if (btrfs_file_extent_type(leaf, fi) ==
3667 BTRFS_FILE_EXTENT_INLINE) {
3668 ptr = btrfs_item_ptr_offset(leaf, slot);
3669 memmove_extent_buffer(leaf, ptr,
3670 (unsigned long)fi,
3671 BTRFS_FILE_EXTENT_INLINE_DATA_START);
3672 }
3673 }
3674
3675 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3676 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
3677 data_end, old_data_start - data_end);
3678
3679 offset = btrfs_disk_key_offset(&disk_key);
3680 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
3681 btrfs_set_item_key(leaf, &disk_key, slot);
3682 if (slot == 0)
3683 fixup_low_keys(path, &disk_key, 1);
3684 }
3685
3686 item = btrfs_item_nr(slot);
3687 btrfs_set_item_size(leaf, item, new_size);
3688 btrfs_mark_buffer_dirty(leaf);
3689
3690 if (btrfs_leaf_free_space(leaf) < 0) {
3691 btrfs_print_leaf(leaf);
3692 BUG();
3693 }
3694}
3695
3696/*
3697 * make the item pointed to by the path bigger, data_size is the added size.
3698 */
3699void btrfs_extend_item(struct btrfs_path *path, u32 data_size)
3700{
3701 int slot;
3702 struct extent_buffer *leaf;
3703 struct btrfs_item *item;
3704 u32 nritems;
3705 unsigned int data_end;
3706 unsigned int old_data;
3707 unsigned int old_size;
3708 int i;
3709 struct btrfs_map_token token;
3710
3711 leaf = path->nodes[0];
3712
3713 nritems = btrfs_header_nritems(leaf);
3714 data_end = leaf_data_end(leaf);
3715
3716 if (btrfs_leaf_free_space(leaf) < data_size) {
3717 btrfs_print_leaf(leaf);
3718 BUG();
3719 }
3720 slot = path->slots[0];
3721 old_data = btrfs_item_end_nr(leaf, slot);
3722
3723 BUG_ON(slot < 0);
3724 if (slot >= nritems) {
3725 btrfs_print_leaf(leaf);
3726 btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
3727 slot, nritems);
3728 BUG();
3729 }
3730
3731 /*
3732 * item0..itemN ... dataN.offset..dataN.size .. data0.size
3733 */
3734 /* first correct the data pointers */
3735 btrfs_init_map_token(&token, leaf);
3736 for (i = slot; i < nritems; i++) {
3737 u32 ioff;
3738 item = btrfs_item_nr(i);
3739
3740 ioff = btrfs_token_item_offset(&token, item);
3741 btrfs_set_token_item_offset(&token, item, ioff - data_size);
3742 }
3743
3744 /* shift the data */
3745 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3746 data_end - data_size, BTRFS_LEAF_DATA_OFFSET +
3747 data_end, old_data - data_end);
3748
3749 data_end = old_data;
3750 old_size = btrfs_item_size_nr(leaf, slot);
3751 item = btrfs_item_nr(slot);
3752 btrfs_set_item_size(leaf, item, old_size + data_size);
3753 btrfs_mark_buffer_dirty(leaf);
3754
3755 if (btrfs_leaf_free_space(leaf) < 0) {
3756 btrfs_print_leaf(leaf);
3757 BUG();
3758 }
3759}
3760
3761/**
3762 * setup_items_for_insert - Helper called before inserting one or more items
3763 * to a leaf. Main purpose is to save stack depth by doing the bulk of the work
3764 * in a function that doesn't call btrfs_search_slot
3765 *
3766 * @root: root we are inserting items to
3767 * @path: points to the leaf/slot where we are going to insert new items
3768 * @cpu_key: array of keys for items to be inserted
3769 * @data_size: size of the body of each item we are going to insert
3770 * @nr: size of @cpu_key/@data_size arrays
3771 */
3772void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
3773 const struct btrfs_key *cpu_key, u32 *data_size,
3774 int nr)
3775{
3776 struct btrfs_fs_info *fs_info = root->fs_info;
3777 struct btrfs_item *item;
3778 int i;
3779 u32 nritems;
3780 unsigned int data_end;
3781 struct btrfs_disk_key disk_key;
3782 struct extent_buffer *leaf;
3783 int slot;
3784 struct btrfs_map_token token;
3785 u32 total_size;
3786 u32 total_data = 0;
3787
3788 for (i = 0; i < nr; i++)
3789 total_data += data_size[i];
3790 total_size = total_data + (nr * sizeof(struct btrfs_item));
3791
3792 if (path->slots[0] == 0) {
3793 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
3794 fixup_low_keys(path, &disk_key, 1);
3795 }
3796 btrfs_unlock_up_safe(path, 1);
3797
3798 leaf = path->nodes[0];
3799 slot = path->slots[0];
3800
3801 nritems = btrfs_header_nritems(leaf);
3802 data_end = leaf_data_end(leaf);
3803
3804 if (btrfs_leaf_free_space(leaf) < total_size) {
3805 btrfs_print_leaf(leaf);
3806 btrfs_crit(fs_info, "not enough freespace need %u have %d",
3807 total_size, btrfs_leaf_free_space(leaf));
3808 BUG();
3809 }
3810
3811 btrfs_init_map_token(&token, leaf);
3812 if (slot != nritems) {
3813 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
3814
3815 if (old_data < data_end) {
3816 btrfs_print_leaf(leaf);
3817 btrfs_crit(fs_info,
3818 "item at slot %d with data offset %u beyond data end of leaf %u",
3819 slot, old_data, data_end);
3820 BUG();
3821 }
3822 /*
3823 * item0..itemN ... dataN.offset..dataN.size .. data0.size
3824 */
3825 /* first correct the data pointers */
3826 for (i = slot; i < nritems; i++) {
3827 u32 ioff;
3828
3829 item = btrfs_item_nr(i);
3830 ioff = btrfs_token_item_offset(&token, item);
3831 btrfs_set_token_item_offset(&token, item,
3832 ioff - total_data);
3833 }
3834 /* shift the items */
3835 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
3836 btrfs_item_nr_offset(slot),
3837 (nritems - slot) * sizeof(struct btrfs_item));
3838
3839 /* shift the data */
3840 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3841 data_end - total_data, BTRFS_LEAF_DATA_OFFSET +
3842 data_end, old_data - data_end);
3843 data_end = old_data;
3844 }
3845
3846 /* setup the item for the new data */
3847 for (i = 0; i < nr; i++) {
3848 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
3849 btrfs_set_item_key(leaf, &disk_key, slot + i);
3850 item = btrfs_item_nr(slot + i);
3851 data_end -= data_size[i];
3852 btrfs_set_token_item_offset(&token, item, data_end);
3853 btrfs_set_token_item_size(&token, item, data_size[i]);
3854 }
3855
3856 btrfs_set_header_nritems(leaf, nritems + nr);
3857 btrfs_mark_buffer_dirty(leaf);
3858
3859 if (btrfs_leaf_free_space(leaf) < 0) {
3860 btrfs_print_leaf(leaf);
3861 BUG();
3862 }
3863}
3864
3865/*
3866 * Given a key and some data, insert items into the tree.
3867 * This does all the path init required, making room in the tree if needed.
3868 */
3869int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
3870 struct btrfs_root *root,
3871 struct btrfs_path *path,
3872 const struct btrfs_key *cpu_key, u32 *data_size,
3873 int nr)
3874{
3875 int ret = 0;
3876 int slot;
3877 int i;
3878 u32 total_size = 0;
3879 u32 total_data = 0;
3880
3881 for (i = 0; i < nr; i++)
3882 total_data += data_size[i];
3883
3884 total_size = total_data + (nr * sizeof(struct btrfs_item));
3885 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
3886 if (ret == 0)
3887 return -EEXIST;
3888 if (ret < 0)
3889 return ret;
3890
3891 slot = path->slots[0];
3892 BUG_ON(slot < 0);
3893
3894 setup_items_for_insert(root, path, cpu_key, data_size, nr);
3895 return 0;
3896}
3897
3898/*
3899 * Given a key and some data, insert an item into the tree.
3900 * This does all the path init required, making room in the tree if needed.
3901 */
3902int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3903 const struct btrfs_key *cpu_key, void *data,
3904 u32 data_size)
3905{
3906 int ret = 0;
3907 struct btrfs_path *path;
3908 struct extent_buffer *leaf;
3909 unsigned long ptr;
3910
3911 path = btrfs_alloc_path();
3912 if (!path)
3913 return -ENOMEM;
3914 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
3915 if (!ret) {
3916 leaf = path->nodes[0];
3917 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
3918 write_extent_buffer(leaf, data, ptr, data_size);
3919 btrfs_mark_buffer_dirty(leaf);
3920 }
3921 btrfs_free_path(path);
3922 return ret;
3923}
3924
3925/*
3926 * delete the pointer from a given node.
3927 *
3928 * the tree should have been previously balanced so the deletion does not
3929 * empty a node.
3930 */
3931static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
3932 int level, int slot)
3933{
3934 struct extent_buffer *parent = path->nodes[level];
3935 u32 nritems;
3936 int ret;
3937
3938 nritems = btrfs_header_nritems(parent);
3939 if (slot != nritems - 1) {
3940 if (level) {
3941 ret = btrfs_tree_mod_log_insert_move(parent, slot,
3942 slot + 1, nritems - slot - 1);
3943 BUG_ON(ret < 0);
3944 }
3945 memmove_extent_buffer(parent,
3946 btrfs_node_key_ptr_offset(slot),
3947 btrfs_node_key_ptr_offset(slot + 1),
3948 sizeof(struct btrfs_key_ptr) *
3949 (nritems - slot - 1));
3950 } else if (level) {
3951 ret = btrfs_tree_mod_log_insert_key(parent, slot,
3952 BTRFS_MOD_LOG_KEY_REMOVE, GFP_NOFS);
3953 BUG_ON(ret < 0);
3954 }
3955
3956 nritems--;
3957 btrfs_set_header_nritems(parent, nritems);
3958 if (nritems == 0 && parent == root->node) {
3959 BUG_ON(btrfs_header_level(root->node) != 1);
3960 /* just turn the root into a leaf and break */
3961 btrfs_set_header_level(root->node, 0);
3962 } else if (slot == 0) {
3963 struct btrfs_disk_key disk_key;
3964
3965 btrfs_node_key(parent, &disk_key, 0);
3966 fixup_low_keys(path, &disk_key, level + 1);
3967 }
3968 btrfs_mark_buffer_dirty(parent);
3969}
3970
3971/*
3972 * a helper function to delete the leaf pointed to by path->slots[1] and
3973 * path->nodes[1].
3974 *
3975 * This deletes the pointer in path->nodes[1] and frees the leaf
3976 * block extent. zero is returned if it all worked out, < 0 otherwise.
3977 *
3978 * The path must have already been setup for deleting the leaf, including
3979 * all the proper balancing. path->nodes[1] must be locked.
3980 */
3981static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
3982 struct btrfs_root *root,
3983 struct btrfs_path *path,
3984 struct extent_buffer *leaf)
3985{
3986 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
3987 del_ptr(root, path, 1, path->slots[1]);
3988
3989 /*
3990 * btrfs_free_extent is expensive, we want to make sure we
3991 * aren't holding any locks when we call it
3992 */
3993 btrfs_unlock_up_safe(path, 0);
3994
3995 root_sub_used(root, leaf->len);
3996
3997 atomic_inc(&leaf->refs);
3998 btrfs_free_tree_block(trans, root, leaf, 0, 1);
3999 free_extent_buffer_stale(leaf);
4000}
4001/*
4002 * delete the item at the leaf level in path. If that empties
4003 * the leaf, remove it from the tree
4004 */
4005int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4006 struct btrfs_path *path, int slot, int nr)
4007{
4008 struct btrfs_fs_info *fs_info = root->fs_info;
4009 struct extent_buffer *leaf;
4010 struct btrfs_item *item;
4011 u32 last_off;
4012 u32 dsize = 0;
4013 int ret = 0;
4014 int wret;
4015 int i;
4016 u32 nritems;
4017
4018 leaf = path->nodes[0];
4019 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4020
4021 for (i = 0; i < nr; i++)
4022 dsize += btrfs_item_size_nr(leaf, slot + i);
4023
4024 nritems = btrfs_header_nritems(leaf);
4025
4026 if (slot + nr != nritems) {
4027 int data_end = leaf_data_end(leaf);
4028 struct btrfs_map_token token;
4029
4030 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4031 data_end + dsize,
4032 BTRFS_LEAF_DATA_OFFSET + data_end,
4033 last_off - data_end);
4034
4035 btrfs_init_map_token(&token, leaf);
4036 for (i = slot + nr; i < nritems; i++) {
4037 u32 ioff;
4038
4039 item = btrfs_item_nr(i);
4040 ioff = btrfs_token_item_offset(&token, item);
4041 btrfs_set_token_item_offset(&token, item, ioff + dsize);
4042 }
4043
4044 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
4045 btrfs_item_nr_offset(slot + nr),
4046 sizeof(struct btrfs_item) *
4047 (nritems - slot - nr));
4048 }
4049 btrfs_set_header_nritems(leaf, nritems - nr);
4050 nritems -= nr;
4051
4052 /* delete the leaf if we've emptied it */
4053 if (nritems == 0) {
4054 if (leaf == root->node) {
4055 btrfs_set_header_level(leaf, 0);
4056 } else {
4057 btrfs_clean_tree_block(leaf);
4058 btrfs_del_leaf(trans, root, path, leaf);
4059 }
4060 } else {
4061 int used = leaf_space_used(leaf, 0, nritems);
4062 if (slot == 0) {
4063 struct btrfs_disk_key disk_key;
4064
4065 btrfs_item_key(leaf, &disk_key, 0);
4066 fixup_low_keys(path, &disk_key, 1);
4067 }
4068
4069 /* delete the leaf if it is mostly empty */
4070 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
4071 /* push_leaf_left fixes the path.
4072 * make sure the path still points to our leaf
4073 * for possible call to del_ptr below
4074 */
4075 slot = path->slots[1];
4076 atomic_inc(&leaf->refs);
4077
4078 wret = push_leaf_left(trans, root, path, 1, 1,
4079 1, (u32)-1);
4080 if (wret < 0 && wret != -ENOSPC)
4081 ret = wret;
4082
4083 if (path->nodes[0] == leaf &&
4084 btrfs_header_nritems(leaf)) {
4085 wret = push_leaf_right(trans, root, path, 1,
4086 1, 1, 0);
4087 if (wret < 0 && wret != -ENOSPC)
4088 ret = wret;
4089 }
4090
4091 if (btrfs_header_nritems(leaf) == 0) {
4092 path->slots[1] = slot;
4093 btrfs_del_leaf(trans, root, path, leaf);
4094 free_extent_buffer(leaf);
4095 ret = 0;
4096 } else {
4097 /* if we're still in the path, make sure
4098 * we're dirty. Otherwise, one of the
4099 * push_leaf functions must have already
4100 * dirtied this buffer
4101 */
4102 if (path->nodes[0] == leaf)
4103 btrfs_mark_buffer_dirty(leaf);
4104 free_extent_buffer(leaf);
4105 }
4106 } else {
4107 btrfs_mark_buffer_dirty(leaf);
4108 }
4109 }
4110 return ret;
4111}
4112
4113/*
4114 * search the tree again to find a leaf with lesser keys
4115 * returns 0 if it found something or 1 if there are no lesser leaves.
4116 * returns < 0 on io errors.
4117 *
4118 * This may release the path, and so you may lose any locks held at the
4119 * time you call it.
4120 */
4121int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
4122{
4123 struct btrfs_key key;
4124 struct btrfs_disk_key found_key;
4125 int ret;
4126
4127 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
4128
4129 if (key.offset > 0) {
4130 key.offset--;
4131 } else if (key.type > 0) {
4132 key.type--;
4133 key.offset = (u64)-1;
4134 } else if (key.objectid > 0) {
4135 key.objectid--;
4136 key.type = (u8)-1;
4137 key.offset = (u64)-1;
4138 } else {
4139 return 1;
4140 }
4141
4142 btrfs_release_path(path);
4143 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4144 if (ret < 0)
4145 return ret;
4146 btrfs_item_key(path->nodes[0], &found_key, 0);
4147 ret = comp_keys(&found_key, &key);
4148 /*
4149 * We might have had an item with the previous key in the tree right
4150 * before we released our path. And after we released our path, that
4151 * item might have been pushed to the first slot (0) of the leaf we
4152 * were holding due to a tree balance. Alternatively, an item with the
4153 * previous key can exist as the only element of a leaf (big fat item).
4154 * Therefore account for these 2 cases, so that our callers (like
4155 * btrfs_previous_item) don't miss an existing item with a key matching
4156 * the previous key we computed above.
4157 */
4158 if (ret <= 0)
4159 return 0;
4160 return 1;
4161}
4162
4163/*
4164 * A helper function to walk down the tree starting at min_key, and looking
4165 * for nodes or leaves that are have a minimum transaction id.
4166 * This is used by the btree defrag code, and tree logging
4167 *
4168 * This does not cow, but it does stuff the starting key it finds back
4169 * into min_key, so you can call btrfs_search_slot with cow=1 on the
4170 * key and get a writable path.
4171 *
4172 * This honors path->lowest_level to prevent descent past a given level
4173 * of the tree.
4174 *
4175 * min_trans indicates the oldest transaction that you are interested
4176 * in walking through. Any nodes or leaves older than min_trans are
4177 * skipped over (without reading them).
4178 *
4179 * returns zero if something useful was found, < 0 on error and 1 if there
4180 * was nothing in the tree that matched the search criteria.
4181 */
4182int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4183 struct btrfs_path *path,
4184 u64 min_trans)
4185{
4186 struct extent_buffer *cur;
4187 struct btrfs_key found_key;
4188 int slot;
4189 int sret;
4190 u32 nritems;
4191 int level;
4192 int ret = 1;
4193 int keep_locks = path->keep_locks;
4194
4195 path->keep_locks = 1;
4196again:
4197 cur = btrfs_read_lock_root_node(root);
4198 level = btrfs_header_level(cur);
4199 WARN_ON(path->nodes[level]);
4200 path->nodes[level] = cur;
4201 path->locks[level] = BTRFS_READ_LOCK;
4202
4203 if (btrfs_header_generation(cur) < min_trans) {
4204 ret = 1;
4205 goto out;
4206 }
4207 while (1) {
4208 nritems = btrfs_header_nritems(cur);
4209 level = btrfs_header_level(cur);
4210 sret = btrfs_bin_search(cur, min_key, &slot);
4211 if (sret < 0) {
4212 ret = sret;
4213 goto out;
4214 }
4215
4216 /* at the lowest level, we're done, setup the path and exit */
4217 if (level == path->lowest_level) {
4218 if (slot >= nritems)
4219 goto find_next_key;
4220 ret = 0;
4221 path->slots[level] = slot;
4222 btrfs_item_key_to_cpu(cur, &found_key, slot);
4223 goto out;
4224 }
4225 if (sret && slot > 0)
4226 slot--;
4227 /*
4228 * check this node pointer against the min_trans parameters.
4229 * If it is too old, skip to the next one.
4230 */
4231 while (slot < nritems) {
4232 u64 gen;
4233
4234 gen = btrfs_node_ptr_generation(cur, slot);
4235 if (gen < min_trans) {
4236 slot++;
4237 continue;
4238 }
4239 break;
4240 }
4241find_next_key:
4242 /*
4243 * we didn't find a candidate key in this node, walk forward
4244 * and find another one
4245 */
4246 if (slot >= nritems) {
4247 path->slots[level] = slot;
4248 sret = btrfs_find_next_key(root, path, min_key, level,
4249 min_trans);
4250 if (sret == 0) {
4251 btrfs_release_path(path);
4252 goto again;
4253 } else {
4254 goto out;
4255 }
4256 }
4257 /* save our key for returning back */
4258 btrfs_node_key_to_cpu(cur, &found_key, slot);
4259 path->slots[level] = slot;
4260 if (level == path->lowest_level) {
4261 ret = 0;
4262 goto out;
4263 }
4264 cur = btrfs_read_node_slot(cur, slot);
4265 if (IS_ERR(cur)) {
4266 ret = PTR_ERR(cur);
4267 goto out;
4268 }
4269
4270 btrfs_tree_read_lock(cur);
4271
4272 path->locks[level - 1] = BTRFS_READ_LOCK;
4273 path->nodes[level - 1] = cur;
4274 unlock_up(path, level, 1, 0, NULL);
4275 }
4276out:
4277 path->keep_locks = keep_locks;
4278 if (ret == 0) {
4279 btrfs_unlock_up_safe(path, path->lowest_level + 1);
4280 memcpy(min_key, &found_key, sizeof(found_key));
4281 }
4282 return ret;
4283}
4284
4285/*
4286 * this is similar to btrfs_next_leaf, but does not try to preserve
4287 * and fixup the path. It looks for and returns the next key in the
4288 * tree based on the current path and the min_trans parameters.
4289 *
4290 * 0 is returned if another key is found, < 0 if there are any errors
4291 * and 1 is returned if there are no higher keys in the tree
4292 *
4293 * path->keep_locks should be set to 1 on the search made before
4294 * calling this function.
4295 */
4296int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4297 struct btrfs_key *key, int level, u64 min_trans)
4298{
4299 int slot;
4300 struct extent_buffer *c;
4301
4302 WARN_ON(!path->keep_locks && !path->skip_locking);
4303 while (level < BTRFS_MAX_LEVEL) {
4304 if (!path->nodes[level])
4305 return 1;
4306
4307 slot = path->slots[level] + 1;
4308 c = path->nodes[level];
4309next:
4310 if (slot >= btrfs_header_nritems(c)) {
4311 int ret;
4312 int orig_lowest;
4313 struct btrfs_key cur_key;
4314 if (level + 1 >= BTRFS_MAX_LEVEL ||
4315 !path->nodes[level + 1])
4316 return 1;
4317
4318 if (path->locks[level + 1] || path->skip_locking) {
4319 level++;
4320 continue;
4321 }
4322
4323 slot = btrfs_header_nritems(c) - 1;
4324 if (level == 0)
4325 btrfs_item_key_to_cpu(c, &cur_key, slot);
4326 else
4327 btrfs_node_key_to_cpu(c, &cur_key, slot);
4328
4329 orig_lowest = path->lowest_level;
4330 btrfs_release_path(path);
4331 path->lowest_level = level;
4332 ret = btrfs_search_slot(NULL, root, &cur_key, path,
4333 0, 0);
4334 path->lowest_level = orig_lowest;
4335 if (ret < 0)
4336 return ret;
4337
4338 c = path->nodes[level];
4339 slot = path->slots[level];
4340 if (ret == 0)
4341 slot++;
4342 goto next;
4343 }
4344
4345 if (level == 0)
4346 btrfs_item_key_to_cpu(c, key, slot);
4347 else {
4348 u64 gen = btrfs_node_ptr_generation(c, slot);
4349
4350 if (gen < min_trans) {
4351 slot++;
4352 goto next;
4353 }
4354 btrfs_node_key_to_cpu(c, key, slot);
4355 }
4356 return 0;
4357 }
4358 return 1;
4359}
4360
4361/*
4362 * search the tree again to find a leaf with greater keys
4363 * returns 0 if it found something or 1 if there are no greater leaves.
4364 * returns < 0 on io errors.
4365 */
4366int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
4367{
4368 return btrfs_next_old_leaf(root, path, 0);
4369}
4370
4371int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
4372 u64 time_seq)
4373{
4374 int slot;
4375 int level;
4376 struct extent_buffer *c;
4377 struct extent_buffer *next;
4378 struct btrfs_key key;
4379 u32 nritems;
4380 int ret;
4381 int i;
4382
4383 nritems = btrfs_header_nritems(path->nodes[0]);
4384 if (nritems == 0)
4385 return 1;
4386
4387 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
4388again:
4389 level = 1;
4390 next = NULL;
4391 btrfs_release_path(path);
4392
4393 path->keep_locks = 1;
4394
4395 if (time_seq)
4396 ret = btrfs_search_old_slot(root, &key, path, time_seq);
4397 else
4398 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4399 path->keep_locks = 0;
4400
4401 if (ret < 0)
4402 return ret;
4403
4404 nritems = btrfs_header_nritems(path->nodes[0]);
4405 /*
4406 * by releasing the path above we dropped all our locks. A balance
4407 * could have added more items next to the key that used to be
4408 * at the very end of the block. So, check again here and
4409 * advance the path if there are now more items available.
4410 */
4411 if (nritems > 0 && path->slots[0] < nritems - 1) {
4412 if (ret == 0)
4413 path->slots[0]++;
4414 ret = 0;
4415 goto done;
4416 }
4417 /*
4418 * So the above check misses one case:
4419 * - after releasing the path above, someone has removed the item that
4420 * used to be at the very end of the block, and balance between leafs
4421 * gets another one with bigger key.offset to replace it.
4422 *
4423 * This one should be returned as well, or we can get leaf corruption
4424 * later(esp. in __btrfs_drop_extents()).
4425 *
4426 * And a bit more explanation about this check,
4427 * with ret > 0, the key isn't found, the path points to the slot
4428 * where it should be inserted, so the path->slots[0] item must be the
4429 * bigger one.
4430 */
4431 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
4432 ret = 0;
4433 goto done;
4434 }
4435
4436 while (level < BTRFS_MAX_LEVEL) {
4437 if (!path->nodes[level]) {
4438 ret = 1;
4439 goto done;
4440 }
4441
4442 slot = path->slots[level] + 1;
4443 c = path->nodes[level];
4444 if (slot >= btrfs_header_nritems(c)) {
4445 level++;
4446 if (level == BTRFS_MAX_LEVEL) {
4447 ret = 1;
4448 goto done;
4449 }
4450 continue;
4451 }
4452
4453
4454 /*
4455 * Our current level is where we're going to start from, and to
4456 * make sure lockdep doesn't complain we need to drop our locks
4457 * and nodes from 0 to our current level.
4458 */
4459 for (i = 0; i < level; i++) {
4460 if (path->locks[level]) {
4461 btrfs_tree_read_unlock(path->nodes[i]);
4462 path->locks[i] = 0;
4463 }
4464 free_extent_buffer(path->nodes[i]);
4465 path->nodes[i] = NULL;
4466 }
4467
4468 next = c;
4469 ret = read_block_for_search(root, path, &next, level,
4470 slot, &key);
4471 if (ret == -EAGAIN)
4472 goto again;
4473
4474 if (ret < 0) {
4475 btrfs_release_path(path);
4476 goto done;
4477 }
4478
4479 if (!path->skip_locking) {
4480 ret = btrfs_try_tree_read_lock(next);
4481 if (!ret && time_seq) {
4482 /*
4483 * If we don't get the lock, we may be racing
4484 * with push_leaf_left, holding that lock while
4485 * itself waiting for the leaf we've currently
4486 * locked. To solve this situation, we give up
4487 * on our lock and cycle.
4488 */
4489 free_extent_buffer(next);
4490 btrfs_release_path(path);
4491 cond_resched();
4492 goto again;
4493 }
4494 if (!ret)
4495 btrfs_tree_read_lock(next);
4496 }
4497 break;
4498 }
4499 path->slots[level] = slot;
4500 while (1) {
4501 level--;
4502 path->nodes[level] = next;
4503 path->slots[level] = 0;
4504 if (!path->skip_locking)
4505 path->locks[level] = BTRFS_READ_LOCK;
4506 if (!level)
4507 break;
4508
4509 ret = read_block_for_search(root, path, &next, level,
4510 0, &key);
4511 if (ret == -EAGAIN)
4512 goto again;
4513
4514 if (ret < 0) {
4515 btrfs_release_path(path);
4516 goto done;
4517 }
4518
4519 if (!path->skip_locking)
4520 btrfs_tree_read_lock(next);
4521 }
4522 ret = 0;
4523done:
4524 unlock_up(path, 0, 1, 0, NULL);
4525
4526 return ret;
4527}
4528
4529/*
4530 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
4531 * searching until it gets past min_objectid or finds an item of 'type'
4532 *
4533 * returns 0 if something is found, 1 if nothing was found and < 0 on error
4534 */
4535int btrfs_previous_item(struct btrfs_root *root,
4536 struct btrfs_path *path, u64 min_objectid,
4537 int type)
4538{
4539 struct btrfs_key found_key;
4540 struct extent_buffer *leaf;
4541 u32 nritems;
4542 int ret;
4543
4544 while (1) {
4545 if (path->slots[0] == 0) {
4546 ret = btrfs_prev_leaf(root, path);
4547 if (ret != 0)
4548 return ret;
4549 } else {
4550 path->slots[0]--;
4551 }
4552 leaf = path->nodes[0];
4553 nritems = btrfs_header_nritems(leaf);
4554 if (nritems == 0)
4555 return 1;
4556 if (path->slots[0] == nritems)
4557 path->slots[0]--;
4558
4559 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
4560 if (found_key.objectid < min_objectid)
4561 break;
4562 if (found_key.type == type)
4563 return 0;
4564 if (found_key.objectid == min_objectid &&
4565 found_key.type < type)
4566 break;
4567 }
4568 return 1;
4569}
4570
4571/*
4572 * search in extent tree to find a previous Metadata/Data extent item with
4573 * min objecitd.
4574 *
4575 * returns 0 if something is found, 1 if nothing was found and < 0 on error
4576 */
4577int btrfs_previous_extent_item(struct btrfs_root *root,
4578 struct btrfs_path *path, u64 min_objectid)
4579{
4580 struct btrfs_key found_key;
4581 struct extent_buffer *leaf;
4582 u32 nritems;
4583 int ret;
4584
4585 while (1) {
4586 if (path->slots[0] == 0) {
4587 ret = btrfs_prev_leaf(root, path);
4588 if (ret != 0)
4589 return ret;
4590 } else {
4591 path->slots[0]--;
4592 }
4593 leaf = path->nodes[0];
4594 nritems = btrfs_header_nritems(leaf);
4595 if (nritems == 0)
4596 return 1;
4597 if (path->slots[0] == nritems)
4598 path->slots[0]--;
4599
4600 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
4601 if (found_key.objectid < min_objectid)
4602 break;
4603 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
4604 found_key.type == BTRFS_METADATA_ITEM_KEY)
4605 return 0;
4606 if (found_key.objectid == min_objectid &&
4607 found_key.type < BTRFS_EXTENT_ITEM_KEY)
4608 break;
4609 }
4610 return 1;
4611}