Loading...
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 <linux/error-injection.h>
11#include "messages.h"
12#include "ctree.h"
13#include "disk-io.h"
14#include "transaction.h"
15#include "print-tree.h"
16#include "locking.h"
17#include "volumes.h"
18#include "qgroup.h"
19#include "tree-mod-log.h"
20#include "tree-checker.h"
21#include "fs.h"
22#include "accessors.h"
23#include "extent-tree.h"
24#include "relocation.h"
25#include "file-item.h"
26
27static struct kmem_cache *btrfs_path_cachep;
28
29static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
30 *root, struct btrfs_path *path, int level);
31static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
32 const struct btrfs_key *ins_key, struct btrfs_path *path,
33 int data_size, int extend);
34static int push_node_left(struct btrfs_trans_handle *trans,
35 struct extent_buffer *dst,
36 struct extent_buffer *src, int empty);
37static int balance_node_right(struct btrfs_trans_handle *trans,
38 struct extent_buffer *dst_buf,
39 struct extent_buffer *src_buf);
40
41static const struct btrfs_csums {
42 u16 size;
43 const char name[10];
44 const char driver[12];
45} btrfs_csums[] = {
46 [BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
47 [BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
48 [BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
49 [BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
50 .driver = "blake2b-256" },
51};
52
53/*
54 * The leaf data grows from end-to-front in the node. this returns the address
55 * of the start of the last item, which is the stop of the leaf data stack.
56 */
57static unsigned int leaf_data_end(const struct extent_buffer *leaf)
58{
59 u32 nr = btrfs_header_nritems(leaf);
60
61 if (nr == 0)
62 return BTRFS_LEAF_DATA_SIZE(leaf->fs_info);
63 return btrfs_item_offset(leaf, nr - 1);
64}
65
66/*
67 * Move data in a @leaf (using memmove, safe for overlapping ranges).
68 *
69 * @leaf: leaf that we're doing a memmove on
70 * @dst_offset: item data offset we're moving to
71 * @src_offset: item data offset were' moving from
72 * @len: length of the data we're moving
73 *
74 * Wrapper around memmove_extent_buffer() that takes into account the header on
75 * the leaf. The btrfs_item offset's start directly after the header, so we
76 * have to adjust any offsets to account for the header in the leaf. This
77 * handles that math to simplify the callers.
78 */
79static inline void memmove_leaf_data(const struct extent_buffer *leaf,
80 unsigned long dst_offset,
81 unsigned long src_offset,
82 unsigned long len)
83{
84 memmove_extent_buffer(leaf, btrfs_item_nr_offset(leaf, 0) + dst_offset,
85 btrfs_item_nr_offset(leaf, 0) + src_offset, len);
86}
87
88/*
89 * Copy item data from @src into @dst at the given @offset.
90 *
91 * @dst: destination leaf that we're copying into
92 * @src: source leaf that we're copying from
93 * @dst_offset: item data offset we're copying to
94 * @src_offset: item data offset were' copying from
95 * @len: length of the data we're copying
96 *
97 * Wrapper around copy_extent_buffer() that takes into account the header on
98 * the leaf. The btrfs_item offset's start directly after the header, so we
99 * have to adjust any offsets to account for the header in the leaf. This
100 * handles that math to simplify the callers.
101 */
102static inline void copy_leaf_data(const struct extent_buffer *dst,
103 const struct extent_buffer *src,
104 unsigned long dst_offset,
105 unsigned long src_offset, unsigned long len)
106{
107 copy_extent_buffer(dst, src, btrfs_item_nr_offset(dst, 0) + dst_offset,
108 btrfs_item_nr_offset(src, 0) + src_offset, len);
109}
110
111/*
112 * Move items in a @leaf (using memmove).
113 *
114 * @dst: destination leaf for the items
115 * @dst_item: the item nr we're copying into
116 * @src_item: the item nr we're copying from
117 * @nr_items: the number of items to copy
118 *
119 * Wrapper around memmove_extent_buffer() that does the math to get the
120 * appropriate offsets into the leaf from the item numbers.
121 */
122static inline void memmove_leaf_items(const struct extent_buffer *leaf,
123 int dst_item, int src_item, int nr_items)
124{
125 memmove_extent_buffer(leaf, btrfs_item_nr_offset(leaf, dst_item),
126 btrfs_item_nr_offset(leaf, src_item),
127 nr_items * sizeof(struct btrfs_item));
128}
129
130/*
131 * Copy items from @src into @dst at the given @offset.
132 *
133 * @dst: destination leaf for the items
134 * @src: source leaf for the items
135 * @dst_item: the item nr we're copying into
136 * @src_item: the item nr we're copying from
137 * @nr_items: the number of items to copy
138 *
139 * Wrapper around copy_extent_buffer() that does the math to get the
140 * appropriate offsets into the leaf from the item numbers.
141 */
142static inline void copy_leaf_items(const struct extent_buffer *dst,
143 const struct extent_buffer *src,
144 int dst_item, int src_item, int nr_items)
145{
146 copy_extent_buffer(dst, src, btrfs_item_nr_offset(dst, dst_item),
147 btrfs_item_nr_offset(src, src_item),
148 nr_items * sizeof(struct btrfs_item));
149}
150
151/* This exists for btrfs-progs usages. */
152u16 btrfs_csum_type_size(u16 type)
153{
154 return btrfs_csums[type].size;
155}
156
157int btrfs_super_csum_size(const struct btrfs_super_block *s)
158{
159 u16 t = btrfs_super_csum_type(s);
160 /*
161 * csum type is validated at mount time
162 */
163 return btrfs_csum_type_size(t);
164}
165
166const char *btrfs_super_csum_name(u16 csum_type)
167{
168 /* csum type is validated at mount time */
169 return btrfs_csums[csum_type].name;
170}
171
172/*
173 * Return driver name if defined, otherwise the name that's also a valid driver
174 * name
175 */
176const char *btrfs_super_csum_driver(u16 csum_type)
177{
178 /* csum type is validated at mount time */
179 return btrfs_csums[csum_type].driver[0] ?
180 btrfs_csums[csum_type].driver :
181 btrfs_csums[csum_type].name;
182}
183
184size_t __attribute_const__ btrfs_get_num_csums(void)
185{
186 return ARRAY_SIZE(btrfs_csums);
187}
188
189struct btrfs_path *btrfs_alloc_path(void)
190{
191 might_sleep();
192
193 return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
194}
195
196/* this also releases the path */
197void btrfs_free_path(struct btrfs_path *p)
198{
199 if (!p)
200 return;
201 btrfs_release_path(p);
202 kmem_cache_free(btrfs_path_cachep, p);
203}
204
205/*
206 * path release drops references on the extent buffers in the path
207 * and it drops any locks held by this path
208 *
209 * It is safe to call this on paths that no locks or extent buffers held.
210 */
211noinline void btrfs_release_path(struct btrfs_path *p)
212{
213 int i;
214
215 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
216 p->slots[i] = 0;
217 if (!p->nodes[i])
218 continue;
219 if (p->locks[i]) {
220 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
221 p->locks[i] = 0;
222 }
223 free_extent_buffer(p->nodes[i]);
224 p->nodes[i] = NULL;
225 }
226}
227
228/*
229 * We want the transaction abort to print stack trace only for errors where the
230 * cause could be a bug, eg. due to ENOSPC, and not for common errors that are
231 * caused by external factors.
232 */
233bool __cold abort_should_print_stack(int error)
234{
235 switch (error) {
236 case -EIO:
237 case -EROFS:
238 case -ENOMEM:
239 return false;
240 }
241 return true;
242}
243
244/*
245 * safely gets a reference on the root node of a tree. A lock
246 * is not taken, so a concurrent writer may put a different node
247 * at the root of the tree. See btrfs_lock_root_node for the
248 * looping required.
249 *
250 * The extent buffer returned by this has a reference taken, so
251 * it won't disappear. It may stop being the root of the tree
252 * at any time because there are no locks held.
253 */
254struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
255{
256 struct extent_buffer *eb;
257
258 while (1) {
259 rcu_read_lock();
260 eb = rcu_dereference(root->node);
261
262 /*
263 * RCU really hurts here, we could free up the root node because
264 * it was COWed but we may not get the new root node yet so do
265 * the inc_not_zero dance and if it doesn't work then
266 * synchronize_rcu and try again.
267 */
268 if (atomic_inc_not_zero(&eb->refs)) {
269 rcu_read_unlock();
270 break;
271 }
272 rcu_read_unlock();
273 synchronize_rcu();
274 }
275 return eb;
276}
277
278/*
279 * Cowonly root (not-shareable trees, everything not subvolume or reloc roots),
280 * just get put onto a simple dirty list. Transaction walks this list to make
281 * sure they get properly updated on disk.
282 */
283static void add_root_to_dirty_list(struct btrfs_root *root)
284{
285 struct btrfs_fs_info *fs_info = root->fs_info;
286
287 if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
288 !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
289 return;
290
291 spin_lock(&fs_info->trans_lock);
292 if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
293 /* Want the extent tree to be the last on the list */
294 if (btrfs_root_id(root) == BTRFS_EXTENT_TREE_OBJECTID)
295 list_move_tail(&root->dirty_list,
296 &fs_info->dirty_cowonly_roots);
297 else
298 list_move(&root->dirty_list,
299 &fs_info->dirty_cowonly_roots);
300 }
301 spin_unlock(&fs_info->trans_lock);
302}
303
304/*
305 * used by snapshot creation to make a copy of a root for a tree with
306 * a given objectid. The buffer with the new root node is returned in
307 * cow_ret, and this func returns zero on success or a negative error code.
308 */
309int btrfs_copy_root(struct btrfs_trans_handle *trans,
310 struct btrfs_root *root,
311 struct extent_buffer *buf,
312 struct extent_buffer **cow_ret, u64 new_root_objectid)
313{
314 struct btrfs_fs_info *fs_info = root->fs_info;
315 struct extent_buffer *cow;
316 int ret = 0;
317 int level;
318 struct btrfs_disk_key disk_key;
319 u64 reloc_src_root = 0;
320
321 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
322 trans->transid != fs_info->running_transaction->transid);
323 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
324 trans->transid != btrfs_get_root_last_trans(root));
325
326 level = btrfs_header_level(buf);
327 if (level == 0)
328 btrfs_item_key(buf, &disk_key, 0);
329 else
330 btrfs_node_key(buf, &disk_key, 0);
331
332 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
333 reloc_src_root = btrfs_header_owner(buf);
334 cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
335 &disk_key, level, buf->start, 0,
336 reloc_src_root, BTRFS_NESTING_NEW_ROOT);
337 if (IS_ERR(cow))
338 return PTR_ERR(cow);
339
340 copy_extent_buffer_full(cow, buf);
341 btrfs_set_header_bytenr(cow, cow->start);
342 btrfs_set_header_generation(cow, trans->transid);
343 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
344 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
345 BTRFS_HEADER_FLAG_RELOC);
346 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
347 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
348 else
349 btrfs_set_header_owner(cow, new_root_objectid);
350
351 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
352
353 WARN_ON(btrfs_header_generation(buf) > trans->transid);
354 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
355 ret = btrfs_inc_ref(trans, root, cow, 1);
356 else
357 ret = btrfs_inc_ref(trans, root, cow, 0);
358 if (ret) {
359 btrfs_tree_unlock(cow);
360 free_extent_buffer(cow);
361 btrfs_abort_transaction(trans, ret);
362 return ret;
363 }
364
365 btrfs_mark_buffer_dirty(trans, cow);
366 *cow_ret = cow;
367 return 0;
368}
369
370/*
371 * check if the tree block can be shared by multiple trees
372 */
373bool btrfs_block_can_be_shared(struct btrfs_trans_handle *trans,
374 struct btrfs_root *root,
375 struct extent_buffer *buf)
376{
377 const u64 buf_gen = btrfs_header_generation(buf);
378
379 /*
380 * Tree blocks not in shareable trees and tree roots are never shared.
381 * If a block was allocated after the last snapshot and the block was
382 * not allocated by tree relocation, we know the block is not shared.
383 */
384
385 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
386 return false;
387
388 if (buf == root->node)
389 return false;
390
391 if (buf_gen > btrfs_root_last_snapshot(&root->root_item) &&
392 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))
393 return false;
394
395 if (buf != root->commit_root)
396 return true;
397
398 /*
399 * An extent buffer that used to be the commit root may still be shared
400 * because the tree height may have increased and it became a child of a
401 * higher level root. This can happen when snapshotting a subvolume
402 * created in the current transaction.
403 */
404 if (buf_gen == trans->transid)
405 return true;
406
407 return false;
408}
409
410static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
411 struct btrfs_root *root,
412 struct extent_buffer *buf,
413 struct extent_buffer *cow,
414 int *last_ref)
415{
416 struct btrfs_fs_info *fs_info = root->fs_info;
417 u64 refs;
418 u64 owner;
419 u64 flags;
420 int ret;
421
422 /*
423 * Backrefs update rules:
424 *
425 * Always use full backrefs for extent pointers in tree block
426 * allocated by tree relocation.
427 *
428 * If a shared tree block is no longer referenced by its owner
429 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
430 * use full backrefs for extent pointers in tree block.
431 *
432 * If a tree block is been relocating
433 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
434 * use full backrefs for extent pointers in tree block.
435 * The reason for this is some operations (such as drop tree)
436 * are only allowed for blocks use full backrefs.
437 */
438
439 if (btrfs_block_can_be_shared(trans, root, buf)) {
440 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
441 btrfs_header_level(buf), 1,
442 &refs, &flags, NULL);
443 if (ret)
444 return ret;
445 if (unlikely(refs == 0)) {
446 btrfs_crit(fs_info,
447 "found 0 references for tree block at bytenr %llu level %d root %llu",
448 buf->start, btrfs_header_level(buf),
449 btrfs_root_id(root));
450 ret = -EUCLEAN;
451 btrfs_abort_transaction(trans, ret);
452 return ret;
453 }
454 } else {
455 refs = 1;
456 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID ||
457 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
458 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
459 else
460 flags = 0;
461 }
462
463 owner = btrfs_header_owner(buf);
464 if (unlikely(owner == BTRFS_TREE_RELOC_OBJECTID &&
465 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))) {
466 btrfs_crit(fs_info,
467"found tree block at bytenr %llu level %d root %llu refs %llu flags %llx without full backref flag set",
468 buf->start, btrfs_header_level(buf),
469 btrfs_root_id(root), refs, flags);
470 ret = -EUCLEAN;
471 btrfs_abort_transaction(trans, ret);
472 return ret;
473 }
474
475 if (refs > 1) {
476 if ((owner == btrfs_root_id(root) ||
477 btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) &&
478 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
479 ret = btrfs_inc_ref(trans, root, buf, 1);
480 if (ret)
481 return ret;
482
483 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) {
484 ret = btrfs_dec_ref(trans, root, buf, 0);
485 if (ret)
486 return ret;
487 ret = btrfs_inc_ref(trans, root, cow, 1);
488 if (ret)
489 return ret;
490 }
491 ret = btrfs_set_disk_extent_flags(trans, buf,
492 BTRFS_BLOCK_FLAG_FULL_BACKREF);
493 if (ret)
494 return ret;
495 } else {
496
497 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
498 ret = btrfs_inc_ref(trans, root, cow, 1);
499 else
500 ret = btrfs_inc_ref(trans, root, cow, 0);
501 if (ret)
502 return ret;
503 }
504 } else {
505 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
506 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
507 ret = btrfs_inc_ref(trans, root, cow, 1);
508 else
509 ret = btrfs_inc_ref(trans, root, cow, 0);
510 if (ret)
511 return ret;
512 ret = btrfs_dec_ref(trans, root, buf, 1);
513 if (ret)
514 return ret;
515 }
516 btrfs_clear_buffer_dirty(trans, buf);
517 *last_ref = 1;
518 }
519 return 0;
520}
521
522/*
523 * does the dirty work in cow of a single block. The parent block (if
524 * supplied) is updated to point to the new cow copy. The new buffer is marked
525 * dirty and returned locked. If you modify the block it needs to be marked
526 * dirty again.
527 *
528 * search_start -- an allocation hint for the new block
529 *
530 * empty_size -- a hint that you plan on doing more cow. This is the size in
531 * bytes the allocator should try to find free next to the block it returns.
532 * This is just a hint and may be ignored by the allocator.
533 */
534int btrfs_force_cow_block(struct btrfs_trans_handle *trans,
535 struct btrfs_root *root,
536 struct extent_buffer *buf,
537 struct extent_buffer *parent, int parent_slot,
538 struct extent_buffer **cow_ret,
539 u64 search_start, u64 empty_size,
540 enum btrfs_lock_nesting nest)
541{
542 struct btrfs_fs_info *fs_info = root->fs_info;
543 struct btrfs_disk_key disk_key;
544 struct extent_buffer *cow;
545 int level, ret;
546 int last_ref = 0;
547 int unlock_orig = 0;
548 u64 parent_start = 0;
549 u64 reloc_src_root = 0;
550
551 if (*cow_ret == buf)
552 unlock_orig = 1;
553
554 btrfs_assert_tree_write_locked(buf);
555
556 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
557 trans->transid != fs_info->running_transaction->transid);
558 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
559 trans->transid != btrfs_get_root_last_trans(root));
560
561 level = btrfs_header_level(buf);
562
563 if (level == 0)
564 btrfs_item_key(buf, &disk_key, 0);
565 else
566 btrfs_node_key(buf, &disk_key, 0);
567
568 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) {
569 if (parent)
570 parent_start = parent->start;
571 reloc_src_root = btrfs_header_owner(buf);
572 }
573 cow = btrfs_alloc_tree_block(trans, root, parent_start,
574 btrfs_root_id(root), &disk_key, level,
575 search_start, empty_size, reloc_src_root, nest);
576 if (IS_ERR(cow))
577 return PTR_ERR(cow);
578
579 /* cow is set to blocking by btrfs_init_new_buffer */
580
581 copy_extent_buffer_full(cow, buf);
582 btrfs_set_header_bytenr(cow, cow->start);
583 btrfs_set_header_generation(cow, trans->transid);
584 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
585 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
586 BTRFS_HEADER_FLAG_RELOC);
587 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
588 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
589 else
590 btrfs_set_header_owner(cow, btrfs_root_id(root));
591
592 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
593
594 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
595 if (ret) {
596 btrfs_abort_transaction(trans, ret);
597 goto error_unlock_cow;
598 }
599
600 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
601 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
602 if (ret) {
603 btrfs_abort_transaction(trans, ret);
604 goto error_unlock_cow;
605 }
606 }
607
608 if (buf == root->node) {
609 WARN_ON(parent && parent != buf);
610 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID ||
611 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
612 parent_start = buf->start;
613
614 ret = btrfs_tree_mod_log_insert_root(root->node, cow, true);
615 if (ret < 0) {
616 btrfs_abort_transaction(trans, ret);
617 goto error_unlock_cow;
618 }
619 atomic_inc(&cow->refs);
620 rcu_assign_pointer(root->node, cow);
621
622 ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
623 parent_start, last_ref);
624 free_extent_buffer(buf);
625 add_root_to_dirty_list(root);
626 if (ret < 0) {
627 btrfs_abort_transaction(trans, ret);
628 goto error_unlock_cow;
629 }
630 } else {
631 WARN_ON(trans->transid != btrfs_header_generation(parent));
632 ret = btrfs_tree_mod_log_insert_key(parent, parent_slot,
633 BTRFS_MOD_LOG_KEY_REPLACE);
634 if (ret) {
635 btrfs_abort_transaction(trans, ret);
636 goto error_unlock_cow;
637 }
638 btrfs_set_node_blockptr(parent, parent_slot,
639 cow->start);
640 btrfs_set_node_ptr_generation(parent, parent_slot,
641 trans->transid);
642 btrfs_mark_buffer_dirty(trans, parent);
643 if (last_ref) {
644 ret = btrfs_tree_mod_log_free_eb(buf);
645 if (ret) {
646 btrfs_abort_transaction(trans, ret);
647 goto error_unlock_cow;
648 }
649 }
650 ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
651 parent_start, last_ref);
652 if (ret < 0) {
653 btrfs_abort_transaction(trans, ret);
654 goto error_unlock_cow;
655 }
656 }
657
658 trace_btrfs_cow_block(root, buf, cow);
659 if (unlock_orig)
660 btrfs_tree_unlock(buf);
661 free_extent_buffer_stale(buf);
662 btrfs_mark_buffer_dirty(trans, cow);
663 *cow_ret = cow;
664 return 0;
665
666error_unlock_cow:
667 btrfs_tree_unlock(cow);
668 free_extent_buffer(cow);
669 return ret;
670}
671
672static inline int should_cow_block(struct btrfs_trans_handle *trans,
673 struct btrfs_root *root,
674 struct extent_buffer *buf)
675{
676 if (btrfs_is_testing(root->fs_info))
677 return 0;
678
679 /* Ensure we can see the FORCE_COW bit */
680 smp_mb__before_atomic();
681
682 /*
683 * We do not need to cow a block if
684 * 1) this block is not created or changed in this transaction;
685 * 2) this block does not belong to TREE_RELOC tree;
686 * 3) the root is not forced COW.
687 *
688 * What is forced COW:
689 * when we create snapshot during committing the transaction,
690 * after we've finished copying src root, we must COW the shared
691 * block to ensure the metadata consistency.
692 */
693 if (btrfs_header_generation(buf) == trans->transid &&
694 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
695 !(btrfs_root_id(root) != BTRFS_TREE_RELOC_OBJECTID &&
696 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
697 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
698 return 0;
699 return 1;
700}
701
702/*
703 * COWs a single block, see btrfs_force_cow_block() for the real work.
704 * This version of it has extra checks so that a block isn't COWed more than
705 * once per transaction, as long as it hasn't been written yet
706 */
707int btrfs_cow_block(struct btrfs_trans_handle *trans,
708 struct btrfs_root *root, struct extent_buffer *buf,
709 struct extent_buffer *parent, int parent_slot,
710 struct extent_buffer **cow_ret,
711 enum btrfs_lock_nesting nest)
712{
713 struct btrfs_fs_info *fs_info = root->fs_info;
714 u64 search_start;
715
716 if (unlikely(test_bit(BTRFS_ROOT_DELETING, &root->state))) {
717 btrfs_abort_transaction(trans, -EUCLEAN);
718 btrfs_crit(fs_info,
719 "attempt to COW block %llu on root %llu that is being deleted",
720 buf->start, btrfs_root_id(root));
721 return -EUCLEAN;
722 }
723
724 /*
725 * COWing must happen through a running transaction, which always
726 * matches the current fs generation (it's a transaction with a state
727 * less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs
728 * into error state to prevent the commit of any transaction.
729 */
730 if (unlikely(trans->transaction != fs_info->running_transaction ||
731 trans->transid != fs_info->generation)) {
732 btrfs_abort_transaction(trans, -EUCLEAN);
733 btrfs_crit(fs_info,
734"unexpected transaction when attempting to COW block %llu on root %llu, transaction %llu running transaction %llu fs generation %llu",
735 buf->start, btrfs_root_id(root), trans->transid,
736 fs_info->running_transaction->transid,
737 fs_info->generation);
738 return -EUCLEAN;
739 }
740
741 if (!should_cow_block(trans, root, buf)) {
742 *cow_ret = buf;
743 return 0;
744 }
745
746 search_start = round_down(buf->start, SZ_1G);
747
748 /*
749 * Before CoWing this block for later modification, check if it's
750 * the subtree root and do the delayed subtree trace if needed.
751 *
752 * Also We don't care about the error, as it's handled internally.
753 */
754 btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
755 return btrfs_force_cow_block(trans, root, buf, parent, parent_slot,
756 cow_ret, search_start, 0, nest);
757}
758ALLOW_ERROR_INJECTION(btrfs_cow_block, ERRNO);
759
760/*
761 * same as comp_keys only with two btrfs_key's
762 */
763int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
764{
765 if (k1->objectid > k2->objectid)
766 return 1;
767 if (k1->objectid < k2->objectid)
768 return -1;
769 if (k1->type > k2->type)
770 return 1;
771 if (k1->type < k2->type)
772 return -1;
773 if (k1->offset > k2->offset)
774 return 1;
775 if (k1->offset < k2->offset)
776 return -1;
777 return 0;
778}
779
780/*
781 * Search for a key in the given extent_buffer.
782 *
783 * The lower boundary for the search is specified by the slot number @first_slot.
784 * Use a value of 0 to search over the whole extent buffer. Works for both
785 * leaves and nodes.
786 *
787 * The slot in the extent buffer is returned via @slot. If the key exists in the
788 * extent buffer, then @slot will point to the slot where the key is, otherwise
789 * it points to the slot where you would insert the key.
790 *
791 * Slot may point to the total number of items (i.e. one position beyond the last
792 * key) if the key is bigger than the last key in the extent buffer.
793 */
794int btrfs_bin_search(struct extent_buffer *eb, int first_slot,
795 const struct btrfs_key *key, int *slot)
796{
797 unsigned long p;
798 int item_size;
799 /*
800 * Use unsigned types for the low and high slots, so that we get a more
801 * efficient division in the search loop below.
802 */
803 u32 low = first_slot;
804 u32 high = btrfs_header_nritems(eb);
805 int ret;
806 const int key_size = sizeof(struct btrfs_disk_key);
807
808 if (unlikely(low > high)) {
809 btrfs_err(eb->fs_info,
810 "%s: low (%u) > high (%u) eb %llu owner %llu level %d",
811 __func__, low, high, eb->start,
812 btrfs_header_owner(eb), btrfs_header_level(eb));
813 return -EINVAL;
814 }
815
816 if (btrfs_header_level(eb) == 0) {
817 p = offsetof(struct btrfs_leaf, items);
818 item_size = sizeof(struct btrfs_item);
819 } else {
820 p = offsetof(struct btrfs_node, ptrs);
821 item_size = sizeof(struct btrfs_key_ptr);
822 }
823
824 while (low < high) {
825 const int unit_size = eb->folio_size;
826 unsigned long oil;
827 unsigned long offset;
828 struct btrfs_disk_key *tmp;
829 struct btrfs_disk_key unaligned;
830 int mid;
831
832 mid = (low + high) / 2;
833 offset = p + mid * item_size;
834 oil = get_eb_offset_in_folio(eb, offset);
835
836 if (oil + key_size <= unit_size) {
837 const unsigned long idx = get_eb_folio_index(eb, offset);
838 char *kaddr = folio_address(eb->folios[idx]);
839
840 oil = get_eb_offset_in_folio(eb, offset);
841 tmp = (struct btrfs_disk_key *)(kaddr + oil);
842 } else {
843 read_extent_buffer(eb, &unaligned, offset, key_size);
844 tmp = &unaligned;
845 }
846
847 ret = btrfs_comp_keys(tmp, key);
848
849 if (ret < 0)
850 low = mid + 1;
851 else if (ret > 0)
852 high = mid;
853 else {
854 *slot = mid;
855 return 0;
856 }
857 }
858 *slot = low;
859 return 1;
860}
861
862static void root_add_used_bytes(struct btrfs_root *root)
863{
864 spin_lock(&root->accounting_lock);
865 btrfs_set_root_used(&root->root_item,
866 btrfs_root_used(&root->root_item) + root->fs_info->nodesize);
867 spin_unlock(&root->accounting_lock);
868}
869
870static void root_sub_used_bytes(struct btrfs_root *root)
871{
872 spin_lock(&root->accounting_lock);
873 btrfs_set_root_used(&root->root_item,
874 btrfs_root_used(&root->root_item) - root->fs_info->nodesize);
875 spin_unlock(&root->accounting_lock);
876}
877
878/* given a node and slot number, this reads the blocks it points to. The
879 * extent buffer is returned with a reference taken (but unlocked).
880 */
881struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
882 int slot)
883{
884 int level = btrfs_header_level(parent);
885 struct btrfs_tree_parent_check check = { 0 };
886 struct extent_buffer *eb;
887
888 if (slot < 0 || slot >= btrfs_header_nritems(parent))
889 return ERR_PTR(-ENOENT);
890
891 ASSERT(level);
892
893 check.level = level - 1;
894 check.transid = btrfs_node_ptr_generation(parent, slot);
895 check.owner_root = btrfs_header_owner(parent);
896 check.has_first_key = true;
897 btrfs_node_key_to_cpu(parent, &check.first_key, slot);
898
899 eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
900 &check);
901 if (IS_ERR(eb))
902 return eb;
903 if (!extent_buffer_uptodate(eb)) {
904 free_extent_buffer(eb);
905 return ERR_PTR(-EIO);
906 }
907
908 return eb;
909}
910
911/*
912 * node level balancing, used to make sure nodes are in proper order for
913 * item deletion. We balance from the top down, so we have to make sure
914 * that a deletion won't leave an node completely empty later on.
915 */
916static noinline int balance_level(struct btrfs_trans_handle *trans,
917 struct btrfs_root *root,
918 struct btrfs_path *path, int level)
919{
920 struct btrfs_fs_info *fs_info = root->fs_info;
921 struct extent_buffer *right = NULL;
922 struct extent_buffer *mid;
923 struct extent_buffer *left = NULL;
924 struct extent_buffer *parent = NULL;
925 int ret = 0;
926 int wret;
927 int pslot;
928 int orig_slot = path->slots[level];
929 u64 orig_ptr;
930
931 ASSERT(level > 0);
932
933 mid = path->nodes[level];
934
935 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK);
936 WARN_ON(btrfs_header_generation(mid) != trans->transid);
937
938 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
939
940 if (level < BTRFS_MAX_LEVEL - 1) {
941 parent = path->nodes[level + 1];
942 pslot = path->slots[level + 1];
943 }
944
945 /*
946 * deal with the case where there is only one pointer in the root
947 * by promoting the node below to a root
948 */
949 if (!parent) {
950 struct extent_buffer *child;
951
952 if (btrfs_header_nritems(mid) != 1)
953 return 0;
954
955 /* promote the child to a root */
956 child = btrfs_read_node_slot(mid, 0);
957 if (IS_ERR(child)) {
958 ret = PTR_ERR(child);
959 goto out;
960 }
961
962 btrfs_tree_lock(child);
963 ret = btrfs_cow_block(trans, root, child, mid, 0, &child,
964 BTRFS_NESTING_COW);
965 if (ret) {
966 btrfs_tree_unlock(child);
967 free_extent_buffer(child);
968 goto out;
969 }
970
971 ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
972 if (ret < 0) {
973 btrfs_tree_unlock(child);
974 free_extent_buffer(child);
975 btrfs_abort_transaction(trans, ret);
976 goto out;
977 }
978 rcu_assign_pointer(root->node, child);
979
980 add_root_to_dirty_list(root);
981 btrfs_tree_unlock(child);
982
983 path->locks[level] = 0;
984 path->nodes[level] = NULL;
985 btrfs_clear_buffer_dirty(trans, mid);
986 btrfs_tree_unlock(mid);
987 /* once for the path */
988 free_extent_buffer(mid);
989
990 root_sub_used_bytes(root);
991 ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
992 /* once for the root ptr */
993 free_extent_buffer_stale(mid);
994 if (ret < 0) {
995 btrfs_abort_transaction(trans, ret);
996 goto out;
997 }
998 return 0;
999 }
1000 if (btrfs_header_nritems(mid) >
1001 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
1002 return 0;
1003
1004 if (pslot) {
1005 left = btrfs_read_node_slot(parent, pslot - 1);
1006 if (IS_ERR(left)) {
1007 ret = PTR_ERR(left);
1008 left = NULL;
1009 goto out;
1010 }
1011
1012 btrfs_tree_lock_nested(left, BTRFS_NESTING_LEFT);
1013 wret = btrfs_cow_block(trans, root, left,
1014 parent, pslot - 1, &left,
1015 BTRFS_NESTING_LEFT_COW);
1016 if (wret) {
1017 ret = wret;
1018 goto out;
1019 }
1020 }
1021
1022 if (pslot + 1 < btrfs_header_nritems(parent)) {
1023 right = btrfs_read_node_slot(parent, pslot + 1);
1024 if (IS_ERR(right)) {
1025 ret = PTR_ERR(right);
1026 right = NULL;
1027 goto out;
1028 }
1029
1030 btrfs_tree_lock_nested(right, BTRFS_NESTING_RIGHT);
1031 wret = btrfs_cow_block(trans, root, right,
1032 parent, pslot + 1, &right,
1033 BTRFS_NESTING_RIGHT_COW);
1034 if (wret) {
1035 ret = wret;
1036 goto out;
1037 }
1038 }
1039
1040 /* first, try to make some room in the middle buffer */
1041 if (left) {
1042 orig_slot += btrfs_header_nritems(left);
1043 wret = push_node_left(trans, left, mid, 1);
1044 if (wret < 0)
1045 ret = wret;
1046 }
1047
1048 /*
1049 * then try to empty the right most buffer into the middle
1050 */
1051 if (right) {
1052 wret = push_node_left(trans, mid, right, 1);
1053 if (wret < 0 && wret != -ENOSPC)
1054 ret = wret;
1055 if (btrfs_header_nritems(right) == 0) {
1056 btrfs_clear_buffer_dirty(trans, right);
1057 btrfs_tree_unlock(right);
1058 ret = btrfs_del_ptr(trans, root, path, level + 1, pslot + 1);
1059 if (ret < 0) {
1060 free_extent_buffer_stale(right);
1061 right = NULL;
1062 goto out;
1063 }
1064 root_sub_used_bytes(root);
1065 ret = btrfs_free_tree_block(trans, btrfs_root_id(root),
1066 right, 0, 1);
1067 free_extent_buffer_stale(right);
1068 right = NULL;
1069 if (ret < 0) {
1070 btrfs_abort_transaction(trans, ret);
1071 goto out;
1072 }
1073 } else {
1074 struct btrfs_disk_key right_key;
1075 btrfs_node_key(right, &right_key, 0);
1076 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1077 BTRFS_MOD_LOG_KEY_REPLACE);
1078 if (ret < 0) {
1079 btrfs_abort_transaction(trans, ret);
1080 goto out;
1081 }
1082 btrfs_set_node_key(parent, &right_key, pslot + 1);
1083 btrfs_mark_buffer_dirty(trans, parent);
1084 }
1085 }
1086 if (btrfs_header_nritems(mid) == 1) {
1087 /*
1088 * we're not allowed to leave a node with one item in the
1089 * tree during a delete. A deletion from lower in the tree
1090 * could try to delete the only pointer in this node.
1091 * So, pull some keys from the left.
1092 * There has to be a left pointer at this point because
1093 * otherwise we would have pulled some pointers from the
1094 * right
1095 */
1096 if (unlikely(!left)) {
1097 btrfs_crit(fs_info,
1098"missing left child when middle child only has 1 item, parent bytenr %llu level %d mid bytenr %llu root %llu",
1099 parent->start, btrfs_header_level(parent),
1100 mid->start, btrfs_root_id(root));
1101 ret = -EUCLEAN;
1102 btrfs_abort_transaction(trans, ret);
1103 goto out;
1104 }
1105 wret = balance_node_right(trans, mid, left);
1106 if (wret < 0) {
1107 ret = wret;
1108 goto out;
1109 }
1110 if (wret == 1) {
1111 wret = push_node_left(trans, left, mid, 1);
1112 if (wret < 0)
1113 ret = wret;
1114 }
1115 BUG_ON(wret == 1);
1116 }
1117 if (btrfs_header_nritems(mid) == 0) {
1118 btrfs_clear_buffer_dirty(trans, mid);
1119 btrfs_tree_unlock(mid);
1120 ret = btrfs_del_ptr(trans, root, path, level + 1, pslot);
1121 if (ret < 0) {
1122 free_extent_buffer_stale(mid);
1123 mid = NULL;
1124 goto out;
1125 }
1126 root_sub_used_bytes(root);
1127 ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
1128 free_extent_buffer_stale(mid);
1129 mid = NULL;
1130 if (ret < 0) {
1131 btrfs_abort_transaction(trans, ret);
1132 goto out;
1133 }
1134 } else {
1135 /* update the parent key to reflect our changes */
1136 struct btrfs_disk_key mid_key;
1137 btrfs_node_key(mid, &mid_key, 0);
1138 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1139 BTRFS_MOD_LOG_KEY_REPLACE);
1140 if (ret < 0) {
1141 btrfs_abort_transaction(trans, ret);
1142 goto out;
1143 }
1144 btrfs_set_node_key(parent, &mid_key, pslot);
1145 btrfs_mark_buffer_dirty(trans, parent);
1146 }
1147
1148 /* update the path */
1149 if (left) {
1150 if (btrfs_header_nritems(left) > orig_slot) {
1151 atomic_inc(&left->refs);
1152 /* left was locked after cow */
1153 path->nodes[level] = left;
1154 path->slots[level + 1] -= 1;
1155 path->slots[level] = orig_slot;
1156 if (mid) {
1157 btrfs_tree_unlock(mid);
1158 free_extent_buffer(mid);
1159 }
1160 } else {
1161 orig_slot -= btrfs_header_nritems(left);
1162 path->slots[level] = orig_slot;
1163 }
1164 }
1165 /* double check we haven't messed things up */
1166 if (orig_ptr !=
1167 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1168 BUG();
1169out:
1170 if (right) {
1171 btrfs_tree_unlock(right);
1172 free_extent_buffer(right);
1173 }
1174 if (left) {
1175 if (path->nodes[level] != left)
1176 btrfs_tree_unlock(left);
1177 free_extent_buffer(left);
1178 }
1179 return ret;
1180}
1181
1182/* Node balancing for insertion. Here we only split or push nodes around
1183 * when they are completely full. This is also done top down, so we
1184 * have to be pessimistic.
1185 */
1186static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1187 struct btrfs_root *root,
1188 struct btrfs_path *path, int level)
1189{
1190 struct btrfs_fs_info *fs_info = root->fs_info;
1191 struct extent_buffer *right = NULL;
1192 struct extent_buffer *mid;
1193 struct extent_buffer *left = NULL;
1194 struct extent_buffer *parent = NULL;
1195 int ret = 0;
1196 int wret;
1197 int pslot;
1198 int orig_slot = path->slots[level];
1199
1200 if (level == 0)
1201 return 1;
1202
1203 mid = path->nodes[level];
1204 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1205
1206 if (level < BTRFS_MAX_LEVEL - 1) {
1207 parent = path->nodes[level + 1];
1208 pslot = path->slots[level + 1];
1209 }
1210
1211 if (!parent)
1212 return 1;
1213
1214 /* first, try to make some room in the middle buffer */
1215 if (pslot) {
1216 u32 left_nr;
1217
1218 left = btrfs_read_node_slot(parent, pslot - 1);
1219 if (IS_ERR(left))
1220 return PTR_ERR(left);
1221
1222 btrfs_tree_lock_nested(left, BTRFS_NESTING_LEFT);
1223
1224 left_nr = btrfs_header_nritems(left);
1225 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1226 wret = 1;
1227 } else {
1228 ret = btrfs_cow_block(trans, root, left, parent,
1229 pslot - 1, &left,
1230 BTRFS_NESTING_LEFT_COW);
1231 if (ret)
1232 wret = 1;
1233 else {
1234 wret = push_node_left(trans, left, mid, 0);
1235 }
1236 }
1237 if (wret < 0)
1238 ret = wret;
1239 if (wret == 0) {
1240 struct btrfs_disk_key disk_key;
1241 orig_slot += left_nr;
1242 btrfs_node_key(mid, &disk_key, 0);
1243 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1244 BTRFS_MOD_LOG_KEY_REPLACE);
1245 if (ret < 0) {
1246 btrfs_tree_unlock(left);
1247 free_extent_buffer(left);
1248 btrfs_abort_transaction(trans, ret);
1249 return ret;
1250 }
1251 btrfs_set_node_key(parent, &disk_key, pslot);
1252 btrfs_mark_buffer_dirty(trans, parent);
1253 if (btrfs_header_nritems(left) > orig_slot) {
1254 path->nodes[level] = left;
1255 path->slots[level + 1] -= 1;
1256 path->slots[level] = orig_slot;
1257 btrfs_tree_unlock(mid);
1258 free_extent_buffer(mid);
1259 } else {
1260 orig_slot -=
1261 btrfs_header_nritems(left);
1262 path->slots[level] = orig_slot;
1263 btrfs_tree_unlock(left);
1264 free_extent_buffer(left);
1265 }
1266 return 0;
1267 }
1268 btrfs_tree_unlock(left);
1269 free_extent_buffer(left);
1270 }
1271
1272 /*
1273 * then try to empty the right most buffer into the middle
1274 */
1275 if (pslot + 1 < btrfs_header_nritems(parent)) {
1276 u32 right_nr;
1277
1278 right = btrfs_read_node_slot(parent, pslot + 1);
1279 if (IS_ERR(right))
1280 return PTR_ERR(right);
1281
1282 btrfs_tree_lock_nested(right, BTRFS_NESTING_RIGHT);
1283
1284 right_nr = btrfs_header_nritems(right);
1285 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1286 wret = 1;
1287 } else {
1288 ret = btrfs_cow_block(trans, root, right,
1289 parent, pslot + 1,
1290 &right, BTRFS_NESTING_RIGHT_COW);
1291 if (ret)
1292 wret = 1;
1293 else {
1294 wret = balance_node_right(trans, right, mid);
1295 }
1296 }
1297 if (wret < 0)
1298 ret = wret;
1299 if (wret == 0) {
1300 struct btrfs_disk_key disk_key;
1301
1302 btrfs_node_key(right, &disk_key, 0);
1303 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1304 BTRFS_MOD_LOG_KEY_REPLACE);
1305 if (ret < 0) {
1306 btrfs_tree_unlock(right);
1307 free_extent_buffer(right);
1308 btrfs_abort_transaction(trans, ret);
1309 return ret;
1310 }
1311 btrfs_set_node_key(parent, &disk_key, pslot + 1);
1312 btrfs_mark_buffer_dirty(trans, parent);
1313
1314 if (btrfs_header_nritems(mid) <= orig_slot) {
1315 path->nodes[level] = right;
1316 path->slots[level + 1] += 1;
1317 path->slots[level] = orig_slot -
1318 btrfs_header_nritems(mid);
1319 btrfs_tree_unlock(mid);
1320 free_extent_buffer(mid);
1321 } else {
1322 btrfs_tree_unlock(right);
1323 free_extent_buffer(right);
1324 }
1325 return 0;
1326 }
1327 btrfs_tree_unlock(right);
1328 free_extent_buffer(right);
1329 }
1330 return 1;
1331}
1332
1333/*
1334 * readahead one full node of leaves, finding things that are close
1335 * to the block in 'slot', and triggering ra on them.
1336 */
1337static void reada_for_search(struct btrfs_fs_info *fs_info,
1338 struct btrfs_path *path,
1339 int level, int slot, u64 objectid)
1340{
1341 struct extent_buffer *node;
1342 struct btrfs_disk_key disk_key;
1343 u32 nritems;
1344 u64 search;
1345 u64 target;
1346 u64 nread = 0;
1347 u64 nread_max;
1348 u32 nr;
1349 u32 blocksize;
1350 u32 nscan = 0;
1351
1352 if (level != 1 && path->reada != READA_FORWARD_ALWAYS)
1353 return;
1354
1355 if (!path->nodes[level])
1356 return;
1357
1358 node = path->nodes[level];
1359
1360 /*
1361 * Since the time between visiting leaves is much shorter than the time
1362 * between visiting nodes, limit read ahead of nodes to 1, to avoid too
1363 * much IO at once (possibly random).
1364 */
1365 if (path->reada == READA_FORWARD_ALWAYS) {
1366 if (level > 1)
1367 nread_max = node->fs_info->nodesize;
1368 else
1369 nread_max = SZ_128K;
1370 } else {
1371 nread_max = SZ_64K;
1372 }
1373
1374 search = btrfs_node_blockptr(node, slot);
1375 blocksize = fs_info->nodesize;
1376 if (path->reada != READA_FORWARD_ALWAYS) {
1377 struct extent_buffer *eb;
1378
1379 eb = find_extent_buffer(fs_info, search);
1380 if (eb) {
1381 free_extent_buffer(eb);
1382 return;
1383 }
1384 }
1385
1386 target = search;
1387
1388 nritems = btrfs_header_nritems(node);
1389 nr = slot;
1390
1391 while (1) {
1392 if (path->reada == READA_BACK) {
1393 if (nr == 0)
1394 break;
1395 nr--;
1396 } else if (path->reada == READA_FORWARD ||
1397 path->reada == READA_FORWARD_ALWAYS) {
1398 nr++;
1399 if (nr >= nritems)
1400 break;
1401 }
1402 if (path->reada == READA_BACK && objectid) {
1403 btrfs_node_key(node, &disk_key, nr);
1404 if (btrfs_disk_key_objectid(&disk_key) != objectid)
1405 break;
1406 }
1407 search = btrfs_node_blockptr(node, nr);
1408 if (path->reada == READA_FORWARD_ALWAYS ||
1409 (search <= target && target - search <= 65536) ||
1410 (search > target && search - target <= 65536)) {
1411 btrfs_readahead_node_child(node, nr);
1412 nread += blocksize;
1413 }
1414 nscan++;
1415 if (nread > nread_max || nscan > 32)
1416 break;
1417 }
1418}
1419
1420static noinline void reada_for_balance(struct btrfs_path *path, int level)
1421{
1422 struct extent_buffer *parent;
1423 int slot;
1424 int nritems;
1425
1426 parent = path->nodes[level + 1];
1427 if (!parent)
1428 return;
1429
1430 nritems = btrfs_header_nritems(parent);
1431 slot = path->slots[level + 1];
1432
1433 if (slot > 0)
1434 btrfs_readahead_node_child(parent, slot - 1);
1435 if (slot + 1 < nritems)
1436 btrfs_readahead_node_child(parent, slot + 1);
1437}
1438
1439
1440/*
1441 * when we walk down the tree, it is usually safe to unlock the higher layers
1442 * in the tree. The exceptions are when our path goes through slot 0, because
1443 * operations on the tree might require changing key pointers higher up in the
1444 * tree.
1445 *
1446 * callers might also have set path->keep_locks, which tells this code to keep
1447 * the lock if the path points to the last slot in the block. This is part of
1448 * walking through the tree, and selecting the next slot in the higher block.
1449 *
1450 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
1451 * if lowest_unlock is 1, level 0 won't be unlocked
1452 */
1453static noinline void unlock_up(struct btrfs_path *path, int level,
1454 int lowest_unlock, int min_write_lock_level,
1455 int *write_lock_level)
1456{
1457 int i;
1458 int skip_level = level;
1459 bool check_skip = true;
1460
1461 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1462 if (!path->nodes[i])
1463 break;
1464 if (!path->locks[i])
1465 break;
1466
1467 if (check_skip) {
1468 if (path->slots[i] == 0) {
1469 skip_level = i + 1;
1470 continue;
1471 }
1472
1473 if (path->keep_locks) {
1474 u32 nritems;
1475
1476 nritems = btrfs_header_nritems(path->nodes[i]);
1477 if (nritems < 1 || path->slots[i] >= nritems - 1) {
1478 skip_level = i + 1;
1479 continue;
1480 }
1481 }
1482 }
1483
1484 if (i >= lowest_unlock && i > skip_level) {
1485 check_skip = false;
1486 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
1487 path->locks[i] = 0;
1488 if (write_lock_level &&
1489 i > min_write_lock_level &&
1490 i <= *write_lock_level) {
1491 *write_lock_level = i - 1;
1492 }
1493 }
1494 }
1495}
1496
1497/*
1498 * Helper function for btrfs_search_slot() and other functions that do a search
1499 * on a btree. The goal is to find a tree block in the cache (the radix tree at
1500 * fs_info->buffer_radix), but if we can't find it, or it's not up to date, read
1501 * its pages from disk.
1502 *
1503 * Returns -EAGAIN, with the path unlocked, if the caller needs to repeat the
1504 * whole btree search, starting again from the current root node.
1505 */
1506static int
1507read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
1508 struct extent_buffer **eb_ret, int slot,
1509 const struct btrfs_key *key)
1510{
1511 struct btrfs_fs_info *fs_info = root->fs_info;
1512 struct btrfs_tree_parent_check check = { 0 };
1513 u64 blocknr;
1514 struct extent_buffer *tmp = NULL;
1515 int ret = 0;
1516 int parent_level;
1517 int err;
1518 bool read_tmp = false;
1519 bool tmp_locked = false;
1520 bool path_released = false;
1521
1522 blocknr = btrfs_node_blockptr(*eb_ret, slot);
1523 parent_level = btrfs_header_level(*eb_ret);
1524 btrfs_node_key_to_cpu(*eb_ret, &check.first_key, slot);
1525 check.has_first_key = true;
1526 check.level = parent_level - 1;
1527 check.transid = btrfs_node_ptr_generation(*eb_ret, slot);
1528 check.owner_root = btrfs_root_id(root);
1529
1530 /*
1531 * If we need to read an extent buffer from disk and we are holding locks
1532 * on upper level nodes, we unlock all the upper nodes before reading the
1533 * extent buffer, and then return -EAGAIN to the caller as it needs to
1534 * restart the search. We don't release the lock on the current level
1535 * because we need to walk this node to figure out which blocks to read.
1536 */
1537 tmp = find_extent_buffer(fs_info, blocknr);
1538 if (tmp) {
1539 if (p->reada == READA_FORWARD_ALWAYS)
1540 reada_for_search(fs_info, p, parent_level, slot, key->objectid);
1541
1542 /* first we do an atomic uptodate check */
1543 if (btrfs_buffer_uptodate(tmp, check.transid, 1) > 0) {
1544 /*
1545 * Do extra check for first_key, eb can be stale due to
1546 * being cached, read from scrub, or have multiple
1547 * parents (shared tree blocks).
1548 */
1549 if (btrfs_verify_level_key(tmp, &check)) {
1550 ret = -EUCLEAN;
1551 goto out;
1552 }
1553 *eb_ret = tmp;
1554 tmp = NULL;
1555 ret = 0;
1556 goto out;
1557 }
1558
1559 if (p->nowait) {
1560 ret = -EAGAIN;
1561 goto out;
1562 }
1563
1564 if (!p->skip_locking) {
1565 btrfs_unlock_up_safe(p, parent_level + 1);
1566 btrfs_maybe_reset_lockdep_class(root, tmp);
1567 tmp_locked = true;
1568 btrfs_tree_read_lock(tmp);
1569 btrfs_release_path(p);
1570 ret = -EAGAIN;
1571 path_released = true;
1572 }
1573
1574 /* Now we're allowed to do a blocking uptodate check. */
1575 err = btrfs_read_extent_buffer(tmp, &check);
1576 if (err) {
1577 ret = err;
1578 goto out;
1579 }
1580
1581 if (ret == 0) {
1582 ASSERT(!tmp_locked);
1583 *eb_ret = tmp;
1584 tmp = NULL;
1585 }
1586 goto out;
1587 } else if (p->nowait) {
1588 ret = -EAGAIN;
1589 goto out;
1590 }
1591
1592 if (!p->skip_locking) {
1593 btrfs_unlock_up_safe(p, parent_level + 1);
1594 ret = -EAGAIN;
1595 }
1596
1597 if (p->reada != READA_NONE)
1598 reada_for_search(fs_info, p, parent_level, slot, key->objectid);
1599
1600 tmp = btrfs_find_create_tree_block(fs_info, blocknr, check.owner_root, check.level);
1601 if (IS_ERR(tmp)) {
1602 ret = PTR_ERR(tmp);
1603 tmp = NULL;
1604 goto out;
1605 }
1606 read_tmp = true;
1607
1608 if (!p->skip_locking) {
1609 ASSERT(ret == -EAGAIN);
1610 btrfs_maybe_reset_lockdep_class(root, tmp);
1611 tmp_locked = true;
1612 btrfs_tree_read_lock(tmp);
1613 btrfs_release_path(p);
1614 path_released = true;
1615 }
1616
1617 /* Now we're allowed to do a blocking uptodate check. */
1618 err = btrfs_read_extent_buffer(tmp, &check);
1619 if (err) {
1620 ret = err;
1621 goto out;
1622 }
1623
1624 /*
1625 * If the read above didn't mark this buffer up to date,
1626 * it will never end up being up to date. Set ret to EIO now
1627 * and give up so that our caller doesn't loop forever
1628 * on our EAGAINs.
1629 */
1630 if (!extent_buffer_uptodate(tmp)) {
1631 ret = -EIO;
1632 goto out;
1633 }
1634
1635 if (ret == 0) {
1636 ASSERT(!tmp_locked);
1637 *eb_ret = tmp;
1638 tmp = NULL;
1639 }
1640out:
1641 if (tmp) {
1642 if (tmp_locked)
1643 btrfs_tree_read_unlock(tmp);
1644 if (read_tmp && ret && ret != -EAGAIN)
1645 free_extent_buffer_stale(tmp);
1646 else
1647 free_extent_buffer(tmp);
1648 }
1649 if (ret && !path_released)
1650 btrfs_release_path(p);
1651
1652 return ret;
1653}
1654
1655/*
1656 * helper function for btrfs_search_slot. This does all of the checks
1657 * for node-level blocks and does any balancing required based on
1658 * the ins_len.
1659 *
1660 * If no extra work was required, zero is returned. If we had to
1661 * drop the path, -EAGAIN is returned and btrfs_search_slot must
1662 * start over
1663 */
1664static int
1665setup_nodes_for_search(struct btrfs_trans_handle *trans,
1666 struct btrfs_root *root, struct btrfs_path *p,
1667 struct extent_buffer *b, int level, int ins_len,
1668 int *write_lock_level)
1669{
1670 struct btrfs_fs_info *fs_info = root->fs_info;
1671 int ret = 0;
1672
1673 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
1674 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
1675
1676 if (*write_lock_level < level + 1) {
1677 *write_lock_level = level + 1;
1678 btrfs_release_path(p);
1679 return -EAGAIN;
1680 }
1681
1682 reada_for_balance(p, level);
1683 ret = split_node(trans, root, p, level);
1684
1685 b = p->nodes[level];
1686 } else if (ins_len < 0 && btrfs_header_nritems(b) <
1687 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
1688
1689 if (*write_lock_level < level + 1) {
1690 *write_lock_level = level + 1;
1691 btrfs_release_path(p);
1692 return -EAGAIN;
1693 }
1694
1695 reada_for_balance(p, level);
1696 ret = balance_level(trans, root, p, level);
1697 if (ret)
1698 return ret;
1699
1700 b = p->nodes[level];
1701 if (!b) {
1702 btrfs_release_path(p);
1703 return -EAGAIN;
1704 }
1705 BUG_ON(btrfs_header_nritems(b) == 1);
1706 }
1707 return ret;
1708}
1709
1710int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
1711 u64 iobjectid, u64 ioff, u8 key_type,
1712 struct btrfs_key *found_key)
1713{
1714 int ret;
1715 struct btrfs_key key;
1716 struct extent_buffer *eb;
1717
1718 ASSERT(path);
1719 ASSERT(found_key);
1720
1721 key.type = key_type;
1722 key.objectid = iobjectid;
1723 key.offset = ioff;
1724
1725 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1726 if (ret < 0)
1727 return ret;
1728
1729 eb = path->nodes[0];
1730 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1731 ret = btrfs_next_leaf(fs_root, path);
1732 if (ret)
1733 return ret;
1734 eb = path->nodes[0];
1735 }
1736
1737 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1738 if (found_key->type != key.type ||
1739 found_key->objectid != key.objectid)
1740 return 1;
1741
1742 return 0;
1743}
1744
1745static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
1746 struct btrfs_path *p,
1747 int write_lock_level)
1748{
1749 struct extent_buffer *b;
1750 int root_lock = 0;
1751 int level = 0;
1752
1753 if (p->search_commit_root) {
1754 b = root->commit_root;
1755 atomic_inc(&b->refs);
1756 level = btrfs_header_level(b);
1757 /*
1758 * Ensure that all callers have set skip_locking when
1759 * p->search_commit_root = 1.
1760 */
1761 ASSERT(p->skip_locking == 1);
1762
1763 goto out;
1764 }
1765
1766 if (p->skip_locking) {
1767 b = btrfs_root_node(root);
1768 level = btrfs_header_level(b);
1769 goto out;
1770 }
1771
1772 /* We try very hard to do read locks on the root */
1773 root_lock = BTRFS_READ_LOCK;
1774
1775 /*
1776 * If the level is set to maximum, we can skip trying to get the read
1777 * lock.
1778 */
1779 if (write_lock_level < BTRFS_MAX_LEVEL) {
1780 /*
1781 * We don't know the level of the root node until we actually
1782 * have it read locked
1783 */
1784 if (p->nowait) {
1785 b = btrfs_try_read_lock_root_node(root);
1786 if (IS_ERR(b))
1787 return b;
1788 } else {
1789 b = btrfs_read_lock_root_node(root);
1790 }
1791 level = btrfs_header_level(b);
1792 if (level > write_lock_level)
1793 goto out;
1794
1795 /* Whoops, must trade for write lock */
1796 btrfs_tree_read_unlock(b);
1797 free_extent_buffer(b);
1798 }
1799
1800 b = btrfs_lock_root_node(root);
1801 root_lock = BTRFS_WRITE_LOCK;
1802
1803 /* The level might have changed, check again */
1804 level = btrfs_header_level(b);
1805
1806out:
1807 /*
1808 * The root may have failed to write out at some point, and thus is no
1809 * longer valid, return an error in this case.
1810 */
1811 if (!extent_buffer_uptodate(b)) {
1812 if (root_lock)
1813 btrfs_tree_unlock_rw(b, root_lock);
1814 free_extent_buffer(b);
1815 return ERR_PTR(-EIO);
1816 }
1817
1818 p->nodes[level] = b;
1819 if (!p->skip_locking)
1820 p->locks[level] = root_lock;
1821 /*
1822 * Callers are responsible for dropping b's references.
1823 */
1824 return b;
1825}
1826
1827/*
1828 * Replace the extent buffer at the lowest level of the path with a cloned
1829 * version. The purpose is to be able to use it safely, after releasing the
1830 * commit root semaphore, even if relocation is happening in parallel, the
1831 * transaction used for relocation is committed and the extent buffer is
1832 * reallocated in the next transaction.
1833 *
1834 * This is used in a context where the caller does not prevent transaction
1835 * commits from happening, either by holding a transaction handle or holding
1836 * some lock, while it's doing searches through a commit root.
1837 * At the moment it's only used for send operations.
1838 */
1839static int finish_need_commit_sem_search(struct btrfs_path *path)
1840{
1841 const int i = path->lowest_level;
1842 const int slot = path->slots[i];
1843 struct extent_buffer *lowest = path->nodes[i];
1844 struct extent_buffer *clone;
1845
1846 ASSERT(path->need_commit_sem);
1847
1848 if (!lowest)
1849 return 0;
1850
1851 lockdep_assert_held_read(&lowest->fs_info->commit_root_sem);
1852
1853 clone = btrfs_clone_extent_buffer(lowest);
1854 if (!clone)
1855 return -ENOMEM;
1856
1857 btrfs_release_path(path);
1858 path->nodes[i] = clone;
1859 path->slots[i] = slot;
1860
1861 return 0;
1862}
1863
1864static inline int search_for_key_slot(struct extent_buffer *eb,
1865 int search_low_slot,
1866 const struct btrfs_key *key,
1867 int prev_cmp,
1868 int *slot)
1869{
1870 /*
1871 * If a previous call to btrfs_bin_search() on a parent node returned an
1872 * exact match (prev_cmp == 0), we can safely assume the target key will
1873 * always be at slot 0 on lower levels, since each key pointer
1874 * (struct btrfs_key_ptr) refers to the lowest key accessible from the
1875 * subtree it points to. Thus we can skip searching lower levels.
1876 */
1877 if (prev_cmp == 0) {
1878 *slot = 0;
1879 return 0;
1880 }
1881
1882 return btrfs_bin_search(eb, search_low_slot, key, slot);
1883}
1884
1885static int search_leaf(struct btrfs_trans_handle *trans,
1886 struct btrfs_root *root,
1887 const struct btrfs_key *key,
1888 struct btrfs_path *path,
1889 int ins_len,
1890 int prev_cmp)
1891{
1892 struct extent_buffer *leaf = path->nodes[0];
1893 int leaf_free_space = -1;
1894 int search_low_slot = 0;
1895 int ret;
1896 bool do_bin_search = true;
1897
1898 /*
1899 * If we are doing an insertion, the leaf has enough free space and the
1900 * destination slot for the key is not slot 0, then we can unlock our
1901 * write lock on the parent, and any other upper nodes, before doing the
1902 * binary search on the leaf (with search_for_key_slot()), allowing other
1903 * tasks to lock the parent and any other upper nodes.
1904 */
1905 if (ins_len > 0) {
1906 /*
1907 * Cache the leaf free space, since we will need it later and it
1908 * will not change until then.
1909 */
1910 leaf_free_space = btrfs_leaf_free_space(leaf);
1911
1912 /*
1913 * !path->locks[1] means we have a single node tree, the leaf is
1914 * the root of the tree.
1915 */
1916 if (path->locks[1] && leaf_free_space >= ins_len) {
1917 struct btrfs_disk_key first_key;
1918
1919 ASSERT(btrfs_header_nritems(leaf) > 0);
1920 btrfs_item_key(leaf, &first_key, 0);
1921
1922 /*
1923 * Doing the extra comparison with the first key is cheap,
1924 * taking into account that the first key is very likely
1925 * already in a cache line because it immediately follows
1926 * the extent buffer's header and we have recently accessed
1927 * the header's level field.
1928 */
1929 ret = btrfs_comp_keys(&first_key, key);
1930 if (ret < 0) {
1931 /*
1932 * The first key is smaller than the key we want
1933 * to insert, so we are safe to unlock all upper
1934 * nodes and we have to do the binary search.
1935 *
1936 * We do use btrfs_unlock_up_safe() and not
1937 * unlock_up() because the later does not unlock
1938 * nodes with a slot of 0 - we can safely unlock
1939 * any node even if its slot is 0 since in this
1940 * case the key does not end up at slot 0 of the
1941 * leaf and there's no need to split the leaf.
1942 */
1943 btrfs_unlock_up_safe(path, 1);
1944 search_low_slot = 1;
1945 } else {
1946 /*
1947 * The first key is >= then the key we want to
1948 * insert, so we can skip the binary search as
1949 * the target key will be at slot 0.
1950 *
1951 * We can not unlock upper nodes when the key is
1952 * less than the first key, because we will need
1953 * to update the key at slot 0 of the parent node
1954 * and possibly of other upper nodes too.
1955 * If the key matches the first key, then we can
1956 * unlock all the upper nodes, using
1957 * btrfs_unlock_up_safe() instead of unlock_up()
1958 * as stated above.
1959 */
1960 if (ret == 0)
1961 btrfs_unlock_up_safe(path, 1);
1962 /*
1963 * ret is already 0 or 1, matching the result of
1964 * a btrfs_bin_search() call, so there is no need
1965 * to adjust it.
1966 */
1967 do_bin_search = false;
1968 path->slots[0] = 0;
1969 }
1970 }
1971 }
1972
1973 if (do_bin_search) {
1974 ret = search_for_key_slot(leaf, search_low_slot, key,
1975 prev_cmp, &path->slots[0]);
1976 if (ret < 0)
1977 return ret;
1978 }
1979
1980 if (ins_len > 0) {
1981 /*
1982 * Item key already exists. In this case, if we are allowed to
1983 * insert the item (for example, in dir_item case, item key
1984 * collision is allowed), it will be merged with the original
1985 * item. Only the item size grows, no new btrfs item will be
1986 * added. If search_for_extension is not set, ins_len already
1987 * accounts the size btrfs_item, deduct it here so leaf space
1988 * check will be correct.
1989 */
1990 if (ret == 0 && !path->search_for_extension) {
1991 ASSERT(ins_len >= sizeof(struct btrfs_item));
1992 ins_len -= sizeof(struct btrfs_item);
1993 }
1994
1995 ASSERT(leaf_free_space >= 0);
1996
1997 if (leaf_free_space < ins_len) {
1998 int err;
1999
2000 err = split_leaf(trans, root, key, path, ins_len,
2001 (ret == 0));
2002 ASSERT(err <= 0);
2003 if (WARN_ON(err > 0))
2004 err = -EUCLEAN;
2005 if (err)
2006 ret = err;
2007 }
2008 }
2009
2010 return ret;
2011}
2012
2013/*
2014 * Look for a key in a tree and perform necessary modifications to preserve
2015 * tree invariants.
2016 *
2017 * @trans: Handle of transaction, used when modifying the tree
2018 * @p: Holds all btree nodes along the search path
2019 * @root: The root node of the tree
2020 * @key: The key we are looking for
2021 * @ins_len: Indicates purpose of search:
2022 * >0 for inserts it's size of item inserted (*)
2023 * <0 for deletions
2024 * 0 for plain searches, not modifying the tree
2025 *
2026 * (*) If size of item inserted doesn't include
2027 * sizeof(struct btrfs_item), then p->search_for_extension must
2028 * be set.
2029 * @cow: boolean should CoW operations be performed. Must always be 1
2030 * when modifying the tree.
2031 *
2032 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
2033 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
2034 *
2035 * If @key is found, 0 is returned and you can find the item in the leaf level
2036 * of the path (level 0)
2037 *
2038 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
2039 * points to the slot where it should be inserted
2040 *
2041 * If an error is encountered while searching the tree a negative error number
2042 * is returned
2043 */
2044int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2045 const struct btrfs_key *key, struct btrfs_path *p,
2046 int ins_len, int cow)
2047{
2048 struct btrfs_fs_info *fs_info;
2049 struct extent_buffer *b;
2050 int slot;
2051 int ret;
2052 int err;
2053 int level;
2054 int lowest_unlock = 1;
2055 /* everything at write_lock_level or lower must be write locked */
2056 int write_lock_level = 0;
2057 u8 lowest_level = 0;
2058 int min_write_lock_level;
2059 int prev_cmp;
2060
2061 if (!root)
2062 return -EINVAL;
2063
2064 fs_info = root->fs_info;
2065 might_sleep();
2066
2067 lowest_level = p->lowest_level;
2068 WARN_ON(lowest_level && ins_len > 0);
2069 WARN_ON(p->nodes[0] != NULL);
2070 BUG_ON(!cow && ins_len);
2071
2072 /*
2073 * For now only allow nowait for read only operations. There's no
2074 * strict reason why we can't, we just only need it for reads so it's
2075 * only implemented for reads.
2076 */
2077 ASSERT(!p->nowait || !cow);
2078
2079 if (ins_len < 0) {
2080 lowest_unlock = 2;
2081
2082 /* when we are removing items, we might have to go up to level
2083 * two as we update tree pointers Make sure we keep write
2084 * for those levels as well
2085 */
2086 write_lock_level = 2;
2087 } else if (ins_len > 0) {
2088 /*
2089 * for inserting items, make sure we have a write lock on
2090 * level 1 so we can update keys
2091 */
2092 write_lock_level = 1;
2093 }
2094
2095 if (!cow)
2096 write_lock_level = -1;
2097
2098 if (cow && (p->keep_locks || p->lowest_level))
2099 write_lock_level = BTRFS_MAX_LEVEL;
2100
2101 min_write_lock_level = write_lock_level;
2102
2103 if (p->need_commit_sem) {
2104 ASSERT(p->search_commit_root);
2105 if (p->nowait) {
2106 if (!down_read_trylock(&fs_info->commit_root_sem))
2107 return -EAGAIN;
2108 } else {
2109 down_read(&fs_info->commit_root_sem);
2110 }
2111 }
2112
2113again:
2114 prev_cmp = -1;
2115 b = btrfs_search_slot_get_root(root, p, write_lock_level);
2116 if (IS_ERR(b)) {
2117 ret = PTR_ERR(b);
2118 goto done;
2119 }
2120
2121 while (b) {
2122 int dec = 0;
2123
2124 level = btrfs_header_level(b);
2125
2126 if (cow) {
2127 bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2128
2129 /*
2130 * if we don't really need to cow this block
2131 * then we don't want to set the path blocking,
2132 * so we test it here
2133 */
2134 if (!should_cow_block(trans, root, b))
2135 goto cow_done;
2136
2137 /*
2138 * must have write locks on this node and the
2139 * parent
2140 */
2141 if (level > write_lock_level ||
2142 (level + 1 > write_lock_level &&
2143 level + 1 < BTRFS_MAX_LEVEL &&
2144 p->nodes[level + 1])) {
2145 write_lock_level = level + 1;
2146 btrfs_release_path(p);
2147 goto again;
2148 }
2149
2150 if (last_level)
2151 err = btrfs_cow_block(trans, root, b, NULL, 0,
2152 &b,
2153 BTRFS_NESTING_COW);
2154 else
2155 err = btrfs_cow_block(trans, root, b,
2156 p->nodes[level + 1],
2157 p->slots[level + 1], &b,
2158 BTRFS_NESTING_COW);
2159 if (err) {
2160 ret = err;
2161 goto done;
2162 }
2163 }
2164cow_done:
2165 p->nodes[level] = b;
2166
2167 /*
2168 * we have a lock on b and as long as we aren't changing
2169 * the tree, there is no way to for the items in b to change.
2170 * It is safe to drop the lock on our parent before we
2171 * go through the expensive btree search on b.
2172 *
2173 * If we're inserting or deleting (ins_len != 0), then we might
2174 * be changing slot zero, which may require changing the parent.
2175 * So, we can't drop the lock until after we know which slot
2176 * we're operating on.
2177 */
2178 if (!ins_len && !p->keep_locks) {
2179 int u = level + 1;
2180
2181 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2182 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2183 p->locks[u] = 0;
2184 }
2185 }
2186
2187 if (level == 0) {
2188 if (ins_len > 0)
2189 ASSERT(write_lock_level >= 1);
2190
2191 ret = search_leaf(trans, root, key, p, ins_len, prev_cmp);
2192 if (!p->search_for_split)
2193 unlock_up(p, level, lowest_unlock,
2194 min_write_lock_level, NULL);
2195 goto done;
2196 }
2197
2198 ret = search_for_key_slot(b, 0, key, prev_cmp, &slot);
2199 if (ret < 0)
2200 goto done;
2201 prev_cmp = ret;
2202
2203 if (ret && slot > 0) {
2204 dec = 1;
2205 slot--;
2206 }
2207 p->slots[level] = slot;
2208 err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
2209 &write_lock_level);
2210 if (err == -EAGAIN)
2211 goto again;
2212 if (err) {
2213 ret = err;
2214 goto done;
2215 }
2216 b = p->nodes[level];
2217 slot = p->slots[level];
2218
2219 /*
2220 * Slot 0 is special, if we change the key we have to update
2221 * the parent pointer which means we must have a write lock on
2222 * the parent
2223 */
2224 if (slot == 0 && ins_len && write_lock_level < level + 1) {
2225 write_lock_level = level + 1;
2226 btrfs_release_path(p);
2227 goto again;
2228 }
2229
2230 unlock_up(p, level, lowest_unlock, min_write_lock_level,
2231 &write_lock_level);
2232
2233 if (level == lowest_level) {
2234 if (dec)
2235 p->slots[level]++;
2236 goto done;
2237 }
2238
2239 err = read_block_for_search(root, p, &b, slot, key);
2240 if (err == -EAGAIN && !p->nowait)
2241 goto again;
2242 if (err) {
2243 ret = err;
2244 goto done;
2245 }
2246
2247 if (!p->skip_locking) {
2248 level = btrfs_header_level(b);
2249
2250 btrfs_maybe_reset_lockdep_class(root, b);
2251
2252 if (level <= write_lock_level) {
2253 btrfs_tree_lock(b);
2254 p->locks[level] = BTRFS_WRITE_LOCK;
2255 } else {
2256 if (p->nowait) {
2257 if (!btrfs_try_tree_read_lock(b)) {
2258 free_extent_buffer(b);
2259 ret = -EAGAIN;
2260 goto done;
2261 }
2262 } else {
2263 btrfs_tree_read_lock(b);
2264 }
2265 p->locks[level] = BTRFS_READ_LOCK;
2266 }
2267 p->nodes[level] = b;
2268 }
2269 }
2270 ret = 1;
2271done:
2272 if (ret < 0 && !p->skip_release_on_error)
2273 btrfs_release_path(p);
2274
2275 if (p->need_commit_sem) {
2276 int ret2;
2277
2278 ret2 = finish_need_commit_sem_search(p);
2279 up_read(&fs_info->commit_root_sem);
2280 if (ret2)
2281 ret = ret2;
2282 }
2283
2284 return ret;
2285}
2286ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO);
2287
2288/*
2289 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2290 * current state of the tree together with the operations recorded in the tree
2291 * modification log to search for the key in a previous version of this tree, as
2292 * denoted by the time_seq parameter.
2293 *
2294 * Naturally, there is no support for insert, delete or cow operations.
2295 *
2296 * The resulting path and return value will be set up as if we called
2297 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2298 */
2299int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2300 struct btrfs_path *p, u64 time_seq)
2301{
2302 struct btrfs_fs_info *fs_info = root->fs_info;
2303 struct extent_buffer *b;
2304 int slot;
2305 int ret;
2306 int err;
2307 int level;
2308 int lowest_unlock = 1;
2309 u8 lowest_level = 0;
2310
2311 lowest_level = p->lowest_level;
2312 WARN_ON(p->nodes[0] != NULL);
2313 ASSERT(!p->nowait);
2314
2315 if (p->search_commit_root) {
2316 BUG_ON(time_seq);
2317 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2318 }
2319
2320again:
2321 b = btrfs_get_old_root(root, time_seq);
2322 if (!b) {
2323 ret = -EIO;
2324 goto done;
2325 }
2326 level = btrfs_header_level(b);
2327 p->locks[level] = BTRFS_READ_LOCK;
2328
2329 while (b) {
2330 int dec = 0;
2331
2332 level = btrfs_header_level(b);
2333 p->nodes[level] = b;
2334
2335 /*
2336 * we have a lock on b and as long as we aren't changing
2337 * the tree, there is no way to for the items in b to change.
2338 * It is safe to drop the lock on our parent before we
2339 * go through the expensive btree search on b.
2340 */
2341 btrfs_unlock_up_safe(p, level + 1);
2342
2343 ret = btrfs_bin_search(b, 0, key, &slot);
2344 if (ret < 0)
2345 goto done;
2346
2347 if (level == 0) {
2348 p->slots[level] = slot;
2349 unlock_up(p, level, lowest_unlock, 0, NULL);
2350 goto done;
2351 }
2352
2353 if (ret && slot > 0) {
2354 dec = 1;
2355 slot--;
2356 }
2357 p->slots[level] = slot;
2358 unlock_up(p, level, lowest_unlock, 0, NULL);
2359
2360 if (level == lowest_level) {
2361 if (dec)
2362 p->slots[level]++;
2363 goto done;
2364 }
2365
2366 err = read_block_for_search(root, p, &b, slot, key);
2367 if (err == -EAGAIN && !p->nowait)
2368 goto again;
2369 if (err) {
2370 ret = err;
2371 goto done;
2372 }
2373
2374 level = btrfs_header_level(b);
2375 btrfs_tree_read_lock(b);
2376 b = btrfs_tree_mod_log_rewind(fs_info, b, time_seq);
2377 if (!b) {
2378 ret = -ENOMEM;
2379 goto done;
2380 }
2381 p->locks[level] = BTRFS_READ_LOCK;
2382 p->nodes[level] = b;
2383 }
2384 ret = 1;
2385done:
2386 if (ret < 0)
2387 btrfs_release_path(p);
2388
2389 return ret;
2390}
2391
2392/*
2393 * Search the tree again to find a leaf with smaller keys.
2394 * Returns 0 if it found something.
2395 * Returns 1 if there are no smaller keys.
2396 * Returns < 0 on error.
2397 *
2398 * This may release the path, and so you may lose any locks held at the
2399 * time you call it.
2400 */
2401static int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
2402{
2403 struct btrfs_key key;
2404 struct btrfs_key orig_key;
2405 struct btrfs_disk_key found_key;
2406 int ret;
2407
2408 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
2409 orig_key = key;
2410
2411 if (key.offset > 0) {
2412 key.offset--;
2413 } else if (key.type > 0) {
2414 key.type--;
2415 key.offset = (u64)-1;
2416 } else if (key.objectid > 0) {
2417 key.objectid--;
2418 key.type = (u8)-1;
2419 key.offset = (u64)-1;
2420 } else {
2421 return 1;
2422 }
2423
2424 btrfs_release_path(path);
2425 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2426 if (ret <= 0)
2427 return ret;
2428
2429 /*
2430 * Previous key not found. Even if we were at slot 0 of the leaf we had
2431 * before releasing the path and calling btrfs_search_slot(), we now may
2432 * be in a slot pointing to the same original key - this can happen if
2433 * after we released the path, one of more items were moved from a
2434 * sibling leaf into the front of the leaf we had due to an insertion
2435 * (see push_leaf_right()).
2436 * If we hit this case and our slot is > 0 and just decrement the slot
2437 * so that the caller does not process the same key again, which may or
2438 * may not break the caller, depending on its logic.
2439 */
2440 if (path->slots[0] < btrfs_header_nritems(path->nodes[0])) {
2441 btrfs_item_key(path->nodes[0], &found_key, path->slots[0]);
2442 ret = btrfs_comp_keys(&found_key, &orig_key);
2443 if (ret == 0) {
2444 if (path->slots[0] > 0) {
2445 path->slots[0]--;
2446 return 0;
2447 }
2448 /*
2449 * At slot 0, same key as before, it means orig_key is
2450 * the lowest, leftmost, key in the tree. We're done.
2451 */
2452 return 1;
2453 }
2454 }
2455
2456 btrfs_item_key(path->nodes[0], &found_key, 0);
2457 ret = btrfs_comp_keys(&found_key, &key);
2458 /*
2459 * We might have had an item with the previous key in the tree right
2460 * before we released our path. And after we released our path, that
2461 * item might have been pushed to the first slot (0) of the leaf we
2462 * were holding due to a tree balance. Alternatively, an item with the
2463 * previous key can exist as the only element of a leaf (big fat item).
2464 * Therefore account for these 2 cases, so that our callers (like
2465 * btrfs_previous_item) don't miss an existing item with a key matching
2466 * the previous key we computed above.
2467 */
2468 if (ret <= 0)
2469 return 0;
2470 return 1;
2471}
2472
2473/*
2474 * helper to use instead of search slot if no exact match is needed but
2475 * instead the next or previous item should be returned.
2476 * When find_higher is true, the next higher item is returned, the next lower
2477 * otherwise.
2478 * When return_any and find_higher are both true, and no higher item is found,
2479 * return the next lower instead.
2480 * When return_any is true and find_higher is false, and no lower item is found,
2481 * return the next higher instead.
2482 * It returns 0 if any item is found, 1 if none is found (tree empty), and
2483 * < 0 on error
2484 */
2485int btrfs_search_slot_for_read(struct btrfs_root *root,
2486 const struct btrfs_key *key,
2487 struct btrfs_path *p, int find_higher,
2488 int return_any)
2489{
2490 int ret;
2491 struct extent_buffer *leaf;
2492
2493again:
2494 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
2495 if (ret <= 0)
2496 return ret;
2497 /*
2498 * a return value of 1 means the path is at the position where the
2499 * item should be inserted. Normally this is the next bigger item,
2500 * but in case the previous item is the last in a leaf, path points
2501 * to the first free slot in the previous leaf, i.e. at an invalid
2502 * item.
2503 */
2504 leaf = p->nodes[0];
2505
2506 if (find_higher) {
2507 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
2508 ret = btrfs_next_leaf(root, p);
2509 if (ret <= 0)
2510 return ret;
2511 if (!return_any)
2512 return 1;
2513 /*
2514 * no higher item found, return the next
2515 * lower instead
2516 */
2517 return_any = 0;
2518 find_higher = 0;
2519 btrfs_release_path(p);
2520 goto again;
2521 }
2522 } else {
2523 if (p->slots[0] == 0) {
2524 ret = btrfs_prev_leaf(root, p);
2525 if (ret < 0)
2526 return ret;
2527 if (!ret) {
2528 leaf = p->nodes[0];
2529 if (p->slots[0] == btrfs_header_nritems(leaf))
2530 p->slots[0]--;
2531 return 0;
2532 }
2533 if (!return_any)
2534 return 1;
2535 /*
2536 * no lower item found, return the next
2537 * higher instead
2538 */
2539 return_any = 0;
2540 find_higher = 1;
2541 btrfs_release_path(p);
2542 goto again;
2543 } else {
2544 --p->slots[0];
2545 }
2546 }
2547 return 0;
2548}
2549
2550/*
2551 * Execute search and call btrfs_previous_item to traverse backwards if the item
2552 * was not found.
2553 *
2554 * Return 0 if found, 1 if not found and < 0 if error.
2555 */
2556int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key,
2557 struct btrfs_path *path)
2558{
2559 int ret;
2560
2561 ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
2562 if (ret > 0)
2563 ret = btrfs_previous_item(root, path, key->objectid, key->type);
2564
2565 if (ret == 0)
2566 btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
2567
2568 return ret;
2569}
2570
2571/*
2572 * Search for a valid slot for the given path.
2573 *
2574 * @root: The root node of the tree.
2575 * @key: Will contain a valid item if found.
2576 * @path: The starting point to validate the slot.
2577 *
2578 * Return: 0 if the item is valid
2579 * 1 if not found
2580 * <0 if error.
2581 */
2582int btrfs_get_next_valid_item(struct btrfs_root *root, struct btrfs_key *key,
2583 struct btrfs_path *path)
2584{
2585 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
2586 int ret;
2587
2588 ret = btrfs_next_leaf(root, path);
2589 if (ret)
2590 return ret;
2591 }
2592
2593 btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
2594 return 0;
2595}
2596
2597/*
2598 * adjust the pointers going up the tree, starting at level
2599 * making sure the right key of each node is points to 'key'.
2600 * This is used after shifting pointers to the left, so it stops
2601 * fixing up pointers when a given leaf/node is not in slot 0 of the
2602 * higher levels
2603 *
2604 */
2605static void fixup_low_keys(struct btrfs_trans_handle *trans,
2606 const struct btrfs_path *path,
2607 const struct btrfs_disk_key *key, int level)
2608{
2609 int i;
2610 struct extent_buffer *t;
2611 int ret;
2612
2613 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2614 int tslot = path->slots[i];
2615
2616 if (!path->nodes[i])
2617 break;
2618 t = path->nodes[i];
2619 ret = btrfs_tree_mod_log_insert_key(t, tslot,
2620 BTRFS_MOD_LOG_KEY_REPLACE);
2621 BUG_ON(ret < 0);
2622 btrfs_set_node_key(t, key, tslot);
2623 btrfs_mark_buffer_dirty(trans, path->nodes[i]);
2624 if (tslot != 0)
2625 break;
2626 }
2627}
2628
2629/*
2630 * update item key.
2631 *
2632 * This function isn't completely safe. It's the caller's responsibility
2633 * that the new key won't break the order
2634 */
2635void btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
2636 const struct btrfs_path *path,
2637 const struct btrfs_key *new_key)
2638{
2639 struct btrfs_fs_info *fs_info = trans->fs_info;
2640 struct btrfs_disk_key disk_key;
2641 struct extent_buffer *eb;
2642 int slot;
2643
2644 eb = path->nodes[0];
2645 slot = path->slots[0];
2646 if (slot > 0) {
2647 btrfs_item_key(eb, &disk_key, slot - 1);
2648 if (unlikely(btrfs_comp_keys(&disk_key, new_key) >= 0)) {
2649 btrfs_print_leaf(eb);
2650 btrfs_crit(fs_info,
2651 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2652 slot, btrfs_disk_key_objectid(&disk_key),
2653 btrfs_disk_key_type(&disk_key),
2654 btrfs_disk_key_offset(&disk_key),
2655 new_key->objectid, new_key->type,
2656 new_key->offset);
2657 BUG();
2658 }
2659 }
2660 if (slot < btrfs_header_nritems(eb) - 1) {
2661 btrfs_item_key(eb, &disk_key, slot + 1);
2662 if (unlikely(btrfs_comp_keys(&disk_key, new_key) <= 0)) {
2663 btrfs_print_leaf(eb);
2664 btrfs_crit(fs_info,
2665 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2666 slot, btrfs_disk_key_objectid(&disk_key),
2667 btrfs_disk_key_type(&disk_key),
2668 btrfs_disk_key_offset(&disk_key),
2669 new_key->objectid, new_key->type,
2670 new_key->offset);
2671 BUG();
2672 }
2673 }
2674
2675 btrfs_cpu_key_to_disk(&disk_key, new_key);
2676 btrfs_set_item_key(eb, &disk_key, slot);
2677 btrfs_mark_buffer_dirty(trans, eb);
2678 if (slot == 0)
2679 fixup_low_keys(trans, path, &disk_key, 1);
2680}
2681
2682/*
2683 * Check key order of two sibling extent buffers.
2684 *
2685 * Return true if something is wrong.
2686 * Return false if everything is fine.
2687 *
2688 * Tree-checker only works inside one tree block, thus the following
2689 * corruption can not be detected by tree-checker:
2690 *
2691 * Leaf @left | Leaf @right
2692 * --------------------------------------------------------------
2693 * | 1 | 2 | 3 | 4 | 5 | f6 | | 7 | 8 |
2694 *
2695 * Key f6 in leaf @left itself is valid, but not valid when the next
2696 * key in leaf @right is 7.
2697 * This can only be checked at tree block merge time.
2698 * And since tree checker has ensured all key order in each tree block
2699 * is correct, we only need to bother the last key of @left and the first
2700 * key of @right.
2701 */
2702static bool check_sibling_keys(const struct extent_buffer *left,
2703 const struct extent_buffer *right)
2704{
2705 struct btrfs_key left_last;
2706 struct btrfs_key right_first;
2707 int level = btrfs_header_level(left);
2708 int nr_left = btrfs_header_nritems(left);
2709 int nr_right = btrfs_header_nritems(right);
2710
2711 /* No key to check in one of the tree blocks */
2712 if (!nr_left || !nr_right)
2713 return false;
2714
2715 if (level) {
2716 btrfs_node_key_to_cpu(left, &left_last, nr_left - 1);
2717 btrfs_node_key_to_cpu(right, &right_first, 0);
2718 } else {
2719 btrfs_item_key_to_cpu(left, &left_last, nr_left - 1);
2720 btrfs_item_key_to_cpu(right, &right_first, 0);
2721 }
2722
2723 if (unlikely(btrfs_comp_cpu_keys(&left_last, &right_first) >= 0)) {
2724 btrfs_crit(left->fs_info, "left extent buffer:");
2725 btrfs_print_tree(left, false);
2726 btrfs_crit(left->fs_info, "right extent buffer:");
2727 btrfs_print_tree(right, false);
2728 btrfs_crit(left->fs_info,
2729"bad key order, sibling blocks, left last (%llu %u %llu) right first (%llu %u %llu)",
2730 left_last.objectid, left_last.type,
2731 left_last.offset, right_first.objectid,
2732 right_first.type, right_first.offset);
2733 return true;
2734 }
2735 return false;
2736}
2737
2738/*
2739 * try to push data from one node into the next node left in the
2740 * tree.
2741 *
2742 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2743 * error, and > 0 if there was no room in the left hand block.
2744 */
2745static int push_node_left(struct btrfs_trans_handle *trans,
2746 struct extent_buffer *dst,
2747 struct extent_buffer *src, int empty)
2748{
2749 struct btrfs_fs_info *fs_info = trans->fs_info;
2750 int push_items = 0;
2751 int src_nritems;
2752 int dst_nritems;
2753 int ret = 0;
2754
2755 src_nritems = btrfs_header_nritems(src);
2756 dst_nritems = btrfs_header_nritems(dst);
2757 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2758 WARN_ON(btrfs_header_generation(src) != trans->transid);
2759 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2760
2761 if (!empty && src_nritems <= 8)
2762 return 1;
2763
2764 if (push_items <= 0)
2765 return 1;
2766
2767 if (empty) {
2768 push_items = min(src_nritems, push_items);
2769 if (push_items < src_nritems) {
2770 /* leave at least 8 pointers in the node if
2771 * we aren't going to empty it
2772 */
2773 if (src_nritems - push_items < 8) {
2774 if (push_items <= 8)
2775 return 1;
2776 push_items -= 8;
2777 }
2778 }
2779 } else
2780 push_items = min(src_nritems - 8, push_items);
2781
2782 /* dst is the left eb, src is the middle eb */
2783 if (check_sibling_keys(dst, src)) {
2784 ret = -EUCLEAN;
2785 btrfs_abort_transaction(trans, ret);
2786 return ret;
2787 }
2788 ret = btrfs_tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
2789 if (ret) {
2790 btrfs_abort_transaction(trans, ret);
2791 return ret;
2792 }
2793 copy_extent_buffer(dst, src,
2794 btrfs_node_key_ptr_offset(dst, dst_nritems),
2795 btrfs_node_key_ptr_offset(src, 0),
2796 push_items * sizeof(struct btrfs_key_ptr));
2797
2798 if (push_items < src_nritems) {
2799 /*
2800 * btrfs_tree_mod_log_eb_copy handles logging the move, so we
2801 * don't need to do an explicit tree mod log operation for it.
2802 */
2803 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(src, 0),
2804 btrfs_node_key_ptr_offset(src, push_items),
2805 (src_nritems - push_items) *
2806 sizeof(struct btrfs_key_ptr));
2807 }
2808 btrfs_set_header_nritems(src, src_nritems - push_items);
2809 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2810 btrfs_mark_buffer_dirty(trans, src);
2811 btrfs_mark_buffer_dirty(trans, dst);
2812
2813 return ret;
2814}
2815
2816/*
2817 * try to push data from one node into the next node right in the
2818 * tree.
2819 *
2820 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
2821 * error, and > 0 if there was no room in the right hand block.
2822 *
2823 * this will only push up to 1/2 the contents of the left node over
2824 */
2825static int balance_node_right(struct btrfs_trans_handle *trans,
2826 struct extent_buffer *dst,
2827 struct extent_buffer *src)
2828{
2829 struct btrfs_fs_info *fs_info = trans->fs_info;
2830 int push_items = 0;
2831 int max_push;
2832 int src_nritems;
2833 int dst_nritems;
2834 int ret = 0;
2835
2836 WARN_ON(btrfs_header_generation(src) != trans->transid);
2837 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2838
2839 src_nritems = btrfs_header_nritems(src);
2840 dst_nritems = btrfs_header_nritems(dst);
2841 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2842 if (push_items <= 0)
2843 return 1;
2844
2845 if (src_nritems < 4)
2846 return 1;
2847
2848 max_push = src_nritems / 2 + 1;
2849 /* don't try to empty the node */
2850 if (max_push >= src_nritems)
2851 return 1;
2852
2853 if (max_push < push_items)
2854 push_items = max_push;
2855
2856 /* dst is the right eb, src is the middle eb */
2857 if (check_sibling_keys(src, dst)) {
2858 ret = -EUCLEAN;
2859 btrfs_abort_transaction(trans, ret);
2860 return ret;
2861 }
2862
2863 /*
2864 * btrfs_tree_mod_log_eb_copy handles logging the move, so we don't
2865 * need to do an explicit tree mod log operation for it.
2866 */
2867 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(dst, push_items),
2868 btrfs_node_key_ptr_offset(dst, 0),
2869 (dst_nritems) *
2870 sizeof(struct btrfs_key_ptr));
2871
2872 ret = btrfs_tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
2873 push_items);
2874 if (ret) {
2875 btrfs_abort_transaction(trans, ret);
2876 return ret;
2877 }
2878 copy_extent_buffer(dst, src,
2879 btrfs_node_key_ptr_offset(dst, 0),
2880 btrfs_node_key_ptr_offset(src, src_nritems - push_items),
2881 push_items * sizeof(struct btrfs_key_ptr));
2882
2883 btrfs_set_header_nritems(src, src_nritems - push_items);
2884 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2885
2886 btrfs_mark_buffer_dirty(trans, src);
2887 btrfs_mark_buffer_dirty(trans, dst);
2888
2889 return ret;
2890}
2891
2892/*
2893 * helper function to insert a new root level in the tree.
2894 * A new node is allocated, and a single item is inserted to
2895 * point to the existing root
2896 *
2897 * returns zero on success or < 0 on failure.
2898 */
2899static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2900 struct btrfs_root *root,
2901 struct btrfs_path *path, int level)
2902{
2903 u64 lower_gen;
2904 struct extent_buffer *lower;
2905 struct extent_buffer *c;
2906 struct extent_buffer *old;
2907 struct btrfs_disk_key lower_key;
2908 int ret;
2909
2910 BUG_ON(path->nodes[level]);
2911 BUG_ON(path->nodes[level-1] != root->node);
2912
2913 lower = path->nodes[level-1];
2914 if (level == 1)
2915 btrfs_item_key(lower, &lower_key, 0);
2916 else
2917 btrfs_node_key(lower, &lower_key, 0);
2918
2919 c = btrfs_alloc_tree_block(trans, root, 0, btrfs_root_id(root),
2920 &lower_key, level, root->node->start, 0,
2921 0, BTRFS_NESTING_NEW_ROOT);
2922 if (IS_ERR(c))
2923 return PTR_ERR(c);
2924
2925 root_add_used_bytes(root);
2926
2927 btrfs_set_header_nritems(c, 1);
2928 btrfs_set_node_key(c, &lower_key, 0);
2929 btrfs_set_node_blockptr(c, 0, lower->start);
2930 lower_gen = btrfs_header_generation(lower);
2931 WARN_ON(lower_gen != trans->transid);
2932
2933 btrfs_set_node_ptr_generation(c, 0, lower_gen);
2934
2935 btrfs_mark_buffer_dirty(trans, c);
2936
2937 old = root->node;
2938 ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
2939 if (ret < 0) {
2940 int ret2;
2941
2942 ret2 = btrfs_free_tree_block(trans, btrfs_root_id(root), c, 0, 1);
2943 if (ret2 < 0)
2944 btrfs_abort_transaction(trans, ret2);
2945 btrfs_tree_unlock(c);
2946 free_extent_buffer(c);
2947 return ret;
2948 }
2949 rcu_assign_pointer(root->node, c);
2950
2951 /* the super has an extra ref to root->node */
2952 free_extent_buffer(old);
2953
2954 add_root_to_dirty_list(root);
2955 atomic_inc(&c->refs);
2956 path->nodes[level] = c;
2957 path->locks[level] = BTRFS_WRITE_LOCK;
2958 path->slots[level] = 0;
2959 return 0;
2960}
2961
2962/*
2963 * worker function to insert a single pointer in a node.
2964 * the node should have enough room for the pointer already
2965 *
2966 * slot and level indicate where you want the key to go, and
2967 * blocknr is the block the key points to.
2968 */
2969static int insert_ptr(struct btrfs_trans_handle *trans,
2970 const struct btrfs_path *path,
2971 const struct btrfs_disk_key *key, u64 bytenr,
2972 int slot, int level)
2973{
2974 struct extent_buffer *lower;
2975 int nritems;
2976 int ret;
2977
2978 BUG_ON(!path->nodes[level]);
2979 btrfs_assert_tree_write_locked(path->nodes[level]);
2980 lower = path->nodes[level];
2981 nritems = btrfs_header_nritems(lower);
2982 BUG_ON(slot > nritems);
2983 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
2984 if (slot != nritems) {
2985 if (level) {
2986 ret = btrfs_tree_mod_log_insert_move(lower, slot + 1,
2987 slot, nritems - slot);
2988 if (ret < 0) {
2989 btrfs_abort_transaction(trans, ret);
2990 return ret;
2991 }
2992 }
2993 memmove_extent_buffer(lower,
2994 btrfs_node_key_ptr_offset(lower, slot + 1),
2995 btrfs_node_key_ptr_offset(lower, slot),
2996 (nritems - slot) * sizeof(struct btrfs_key_ptr));
2997 }
2998 if (level) {
2999 ret = btrfs_tree_mod_log_insert_key(lower, slot,
3000 BTRFS_MOD_LOG_KEY_ADD);
3001 if (ret < 0) {
3002 btrfs_abort_transaction(trans, ret);
3003 return ret;
3004 }
3005 }
3006 btrfs_set_node_key(lower, key, slot);
3007 btrfs_set_node_blockptr(lower, slot, bytenr);
3008 WARN_ON(trans->transid == 0);
3009 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3010 btrfs_set_header_nritems(lower, nritems + 1);
3011 btrfs_mark_buffer_dirty(trans, lower);
3012
3013 return 0;
3014}
3015
3016/*
3017 * split the node at the specified level in path in two.
3018 * The path is corrected to point to the appropriate node after the split
3019 *
3020 * Before splitting this tries to make some room in the node by pushing
3021 * left and right, if either one works, it returns right away.
3022 *
3023 * returns 0 on success and < 0 on failure
3024 */
3025static noinline int split_node(struct btrfs_trans_handle *trans,
3026 struct btrfs_root *root,
3027 struct btrfs_path *path, int level)
3028{
3029 struct btrfs_fs_info *fs_info = root->fs_info;
3030 struct extent_buffer *c;
3031 struct extent_buffer *split;
3032 struct btrfs_disk_key disk_key;
3033 int mid;
3034 int ret;
3035 u32 c_nritems;
3036
3037 c = path->nodes[level];
3038 WARN_ON(btrfs_header_generation(c) != trans->transid);
3039 if (c == root->node) {
3040 /*
3041 * trying to split the root, lets make a new one
3042 *
3043 * tree mod log: We don't log_removal old root in
3044 * insert_new_root, because that root buffer will be kept as a
3045 * normal node. We are going to log removal of half of the
3046 * elements below with btrfs_tree_mod_log_eb_copy(). We're
3047 * holding a tree lock on the buffer, which is why we cannot
3048 * race with other tree_mod_log users.
3049 */
3050 ret = insert_new_root(trans, root, path, level + 1);
3051 if (ret)
3052 return ret;
3053 } else {
3054 ret = push_nodes_for_insert(trans, root, path, level);
3055 c = path->nodes[level];
3056 if (!ret && btrfs_header_nritems(c) <
3057 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
3058 return 0;
3059 if (ret < 0)
3060 return ret;
3061 }
3062
3063 c_nritems = btrfs_header_nritems(c);
3064 mid = (c_nritems + 1) / 2;
3065 btrfs_node_key(c, &disk_key, mid);
3066
3067 split = btrfs_alloc_tree_block(trans, root, 0, btrfs_root_id(root),
3068 &disk_key, level, c->start, 0,
3069 0, BTRFS_NESTING_SPLIT);
3070 if (IS_ERR(split))
3071 return PTR_ERR(split);
3072
3073 root_add_used_bytes(root);
3074 ASSERT(btrfs_header_level(c) == level);
3075
3076 ret = btrfs_tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
3077 if (ret) {
3078 btrfs_tree_unlock(split);
3079 free_extent_buffer(split);
3080 btrfs_abort_transaction(trans, ret);
3081 return ret;
3082 }
3083 copy_extent_buffer(split, c,
3084 btrfs_node_key_ptr_offset(split, 0),
3085 btrfs_node_key_ptr_offset(c, mid),
3086 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3087 btrfs_set_header_nritems(split, c_nritems - mid);
3088 btrfs_set_header_nritems(c, mid);
3089
3090 btrfs_mark_buffer_dirty(trans, c);
3091 btrfs_mark_buffer_dirty(trans, split);
3092
3093 ret = insert_ptr(trans, path, &disk_key, split->start,
3094 path->slots[level + 1] + 1, level + 1);
3095 if (ret < 0) {
3096 btrfs_tree_unlock(split);
3097 free_extent_buffer(split);
3098 return ret;
3099 }
3100
3101 if (path->slots[level] >= mid) {
3102 path->slots[level] -= mid;
3103 btrfs_tree_unlock(c);
3104 free_extent_buffer(c);
3105 path->nodes[level] = split;
3106 path->slots[level + 1] += 1;
3107 } else {
3108 btrfs_tree_unlock(split);
3109 free_extent_buffer(split);
3110 }
3111 return 0;
3112}
3113
3114/*
3115 * how many bytes are required to store the items in a leaf. start
3116 * and nr indicate which items in the leaf to check. This totals up the
3117 * space used both by the item structs and the item data
3118 */
3119static int leaf_space_used(const struct extent_buffer *l, int start, int nr)
3120{
3121 int data_len;
3122 int nritems = btrfs_header_nritems(l);
3123 int end = min(nritems, start + nr) - 1;
3124
3125 if (!nr)
3126 return 0;
3127 data_len = btrfs_item_offset(l, start) + btrfs_item_size(l, start);
3128 data_len = data_len - btrfs_item_offset(l, end);
3129 data_len += sizeof(struct btrfs_item) * nr;
3130 WARN_ON(data_len < 0);
3131 return data_len;
3132}
3133
3134/*
3135 * The space between the end of the leaf items and
3136 * the start of the leaf data. IOW, how much room
3137 * the leaf has left for both items and data
3138 */
3139int btrfs_leaf_free_space(const struct extent_buffer *leaf)
3140{
3141 struct btrfs_fs_info *fs_info = leaf->fs_info;
3142 int nritems = btrfs_header_nritems(leaf);
3143 int ret;
3144
3145 ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
3146 if (ret < 0) {
3147 btrfs_crit(fs_info,
3148 "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3149 ret,
3150 (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
3151 leaf_space_used(leaf, 0, nritems), nritems);
3152 }
3153 return ret;
3154}
3155
3156/*
3157 * min slot controls the lowest index we're willing to push to the
3158 * right. We'll push up to and including min_slot, but no lower
3159 */
3160static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
3161 struct btrfs_path *path,
3162 int data_size, int empty,
3163 struct extent_buffer *right,
3164 int free_space, u32 left_nritems,
3165 u32 min_slot)
3166{
3167 struct btrfs_fs_info *fs_info = right->fs_info;
3168 struct extent_buffer *left = path->nodes[0];
3169 struct extent_buffer *upper = path->nodes[1];
3170 struct btrfs_map_token token;
3171 struct btrfs_disk_key disk_key;
3172 int slot;
3173 u32 i;
3174 int push_space = 0;
3175 int push_items = 0;
3176 u32 nr;
3177 u32 right_nritems;
3178 u32 data_end;
3179 u32 this_item_size;
3180
3181 if (empty)
3182 nr = 0;
3183 else
3184 nr = max_t(u32, 1, min_slot);
3185
3186 if (path->slots[0] >= left_nritems)
3187 push_space += data_size;
3188
3189 slot = path->slots[1];
3190 i = left_nritems - 1;
3191 while (i >= nr) {
3192 if (!empty && push_items > 0) {
3193 if (path->slots[0] > i)
3194 break;
3195 if (path->slots[0] == i) {
3196 int space = btrfs_leaf_free_space(left);
3197
3198 if (space + push_space * 2 > free_space)
3199 break;
3200 }
3201 }
3202
3203 if (path->slots[0] == i)
3204 push_space += data_size;
3205
3206 this_item_size = btrfs_item_size(left, i);
3207 if (this_item_size + sizeof(struct btrfs_item) +
3208 push_space > free_space)
3209 break;
3210
3211 push_items++;
3212 push_space += this_item_size + sizeof(struct btrfs_item);
3213 if (i == 0)
3214 break;
3215 i--;
3216 }
3217
3218 if (push_items == 0)
3219 goto out_unlock;
3220
3221 WARN_ON(!empty && push_items == left_nritems);
3222
3223 /* push left to right */
3224 right_nritems = btrfs_header_nritems(right);
3225
3226 push_space = btrfs_item_data_end(left, left_nritems - push_items);
3227 push_space -= leaf_data_end(left);
3228
3229 /* make room in the right data area */
3230 data_end = leaf_data_end(right);
3231 memmove_leaf_data(right, data_end - push_space, data_end,
3232 BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
3233
3234 /* copy from the left data area */
3235 copy_leaf_data(right, left, BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3236 leaf_data_end(left), push_space);
3237
3238 memmove_leaf_items(right, push_items, 0, right_nritems);
3239
3240 /* copy the items from left to right */
3241 copy_leaf_items(right, left, 0, left_nritems - push_items, push_items);
3242
3243 /* update the item pointers */
3244 btrfs_init_map_token(&token, right);
3245 right_nritems += push_items;
3246 btrfs_set_header_nritems(right, right_nritems);
3247 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3248 for (i = 0; i < right_nritems; i++) {
3249 push_space -= btrfs_token_item_size(&token, i);
3250 btrfs_set_token_item_offset(&token, i, push_space);
3251 }
3252
3253 left_nritems -= push_items;
3254 btrfs_set_header_nritems(left, left_nritems);
3255
3256 if (left_nritems)
3257 btrfs_mark_buffer_dirty(trans, left);
3258 else
3259 btrfs_clear_buffer_dirty(trans, left);
3260
3261 btrfs_mark_buffer_dirty(trans, right);
3262
3263 btrfs_item_key(right, &disk_key, 0);
3264 btrfs_set_node_key(upper, &disk_key, slot + 1);
3265 btrfs_mark_buffer_dirty(trans, upper);
3266
3267 /* then fixup the leaf pointer in the path */
3268 if (path->slots[0] >= left_nritems) {
3269 path->slots[0] -= left_nritems;
3270 if (btrfs_header_nritems(path->nodes[0]) == 0)
3271 btrfs_clear_buffer_dirty(trans, path->nodes[0]);
3272 btrfs_tree_unlock(path->nodes[0]);
3273 free_extent_buffer(path->nodes[0]);
3274 path->nodes[0] = right;
3275 path->slots[1] += 1;
3276 } else {
3277 btrfs_tree_unlock(right);
3278 free_extent_buffer(right);
3279 }
3280 return 0;
3281
3282out_unlock:
3283 btrfs_tree_unlock(right);
3284 free_extent_buffer(right);
3285 return 1;
3286}
3287
3288/*
3289 * push some data in the path leaf to the right, trying to free up at
3290 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3291 *
3292 * returns 1 if the push failed because the other node didn't have enough
3293 * room, 0 if everything worked out and < 0 if there were major errors.
3294 *
3295 * this will push starting from min_slot to the end of the leaf. It won't
3296 * push any slot lower than min_slot
3297 */
3298static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3299 *root, struct btrfs_path *path,
3300 int min_data_size, int data_size,
3301 int empty, u32 min_slot)
3302{
3303 struct extent_buffer *left = path->nodes[0];
3304 struct extent_buffer *right;
3305 struct extent_buffer *upper;
3306 int slot;
3307 int free_space;
3308 u32 left_nritems;
3309 int ret;
3310
3311 if (!path->nodes[1])
3312 return 1;
3313
3314 slot = path->slots[1];
3315 upper = path->nodes[1];
3316 if (slot >= btrfs_header_nritems(upper) - 1)
3317 return 1;
3318
3319 btrfs_assert_tree_write_locked(path->nodes[1]);
3320
3321 right = btrfs_read_node_slot(upper, slot + 1);
3322 if (IS_ERR(right))
3323 return PTR_ERR(right);
3324
3325 btrfs_tree_lock_nested(right, BTRFS_NESTING_RIGHT);
3326
3327 free_space = btrfs_leaf_free_space(right);
3328 if (free_space < data_size)
3329 goto out_unlock;
3330
3331 ret = btrfs_cow_block(trans, root, right, upper,
3332 slot + 1, &right, BTRFS_NESTING_RIGHT_COW);
3333 if (ret)
3334 goto out_unlock;
3335
3336 left_nritems = btrfs_header_nritems(left);
3337 if (left_nritems == 0)
3338 goto out_unlock;
3339
3340 if (check_sibling_keys(left, right)) {
3341 ret = -EUCLEAN;
3342 btrfs_abort_transaction(trans, ret);
3343 btrfs_tree_unlock(right);
3344 free_extent_buffer(right);
3345 return ret;
3346 }
3347 if (path->slots[0] == left_nritems && !empty) {
3348 /* Key greater than all keys in the leaf, right neighbor has
3349 * enough room for it and we're not emptying our leaf to delete
3350 * it, therefore use right neighbor to insert the new item and
3351 * no need to touch/dirty our left leaf. */
3352 btrfs_tree_unlock(left);
3353 free_extent_buffer(left);
3354 path->nodes[0] = right;
3355 path->slots[0] = 0;
3356 path->slots[1]++;
3357 return 0;
3358 }
3359
3360 return __push_leaf_right(trans, path, min_data_size, empty, right,
3361 free_space, left_nritems, min_slot);
3362out_unlock:
3363 btrfs_tree_unlock(right);
3364 free_extent_buffer(right);
3365 return 1;
3366}
3367
3368/*
3369 * push some data in the path leaf to the left, trying to free up at
3370 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3371 *
3372 * max_slot can put a limit on how far into the leaf we'll push items. The
3373 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3374 * items
3375 */
3376static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
3377 struct btrfs_path *path, int data_size,
3378 int empty, struct extent_buffer *left,
3379 int free_space, u32 right_nritems,
3380 u32 max_slot)
3381{
3382 struct btrfs_fs_info *fs_info = left->fs_info;
3383 struct btrfs_disk_key disk_key;
3384 struct extent_buffer *right = path->nodes[0];
3385 int i;
3386 int push_space = 0;
3387 int push_items = 0;
3388 u32 old_left_nritems;
3389 u32 nr;
3390 int ret = 0;
3391 u32 this_item_size;
3392 u32 old_left_item_size;
3393 struct btrfs_map_token token;
3394
3395 if (empty)
3396 nr = min(right_nritems, max_slot);
3397 else
3398 nr = min(right_nritems - 1, max_slot);
3399
3400 for (i = 0; i < nr; i++) {
3401 if (!empty && push_items > 0) {
3402 if (path->slots[0] < i)
3403 break;
3404 if (path->slots[0] == i) {
3405 int space = btrfs_leaf_free_space(right);
3406
3407 if (space + push_space * 2 > free_space)
3408 break;
3409 }
3410 }
3411
3412 if (path->slots[0] == i)
3413 push_space += data_size;
3414
3415 this_item_size = btrfs_item_size(right, i);
3416 if (this_item_size + sizeof(struct btrfs_item) + push_space >
3417 free_space)
3418 break;
3419
3420 push_items++;
3421 push_space += this_item_size + sizeof(struct btrfs_item);
3422 }
3423
3424 if (push_items == 0) {
3425 ret = 1;
3426 goto out;
3427 }
3428 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3429
3430 /* push data from right to left */
3431 copy_leaf_items(left, right, btrfs_header_nritems(left), 0, push_items);
3432
3433 push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3434 btrfs_item_offset(right, push_items - 1);
3435
3436 copy_leaf_data(left, right, leaf_data_end(left) - push_space,
3437 btrfs_item_offset(right, push_items - 1), push_space);
3438 old_left_nritems = btrfs_header_nritems(left);
3439 BUG_ON(old_left_nritems <= 0);
3440
3441 btrfs_init_map_token(&token, left);
3442 old_left_item_size = btrfs_item_offset(left, old_left_nritems - 1);
3443 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3444 u32 ioff;
3445
3446 ioff = btrfs_token_item_offset(&token, i);
3447 btrfs_set_token_item_offset(&token, i,
3448 ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size));
3449 }
3450 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3451
3452 /* fixup right node */
3453 if (push_items > right_nritems)
3454 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3455 right_nritems);
3456
3457 if (push_items < right_nritems) {
3458 push_space = btrfs_item_offset(right, push_items - 1) -
3459 leaf_data_end(right);
3460 memmove_leaf_data(right,
3461 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3462 leaf_data_end(right), push_space);
3463
3464 memmove_leaf_items(right, 0, push_items,
3465 btrfs_header_nritems(right) - push_items);
3466 }
3467
3468 btrfs_init_map_token(&token, right);
3469 right_nritems -= push_items;
3470 btrfs_set_header_nritems(right, right_nritems);
3471 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3472 for (i = 0; i < right_nritems; i++) {
3473 push_space = push_space - btrfs_token_item_size(&token, i);
3474 btrfs_set_token_item_offset(&token, i, push_space);
3475 }
3476
3477 btrfs_mark_buffer_dirty(trans, left);
3478 if (right_nritems)
3479 btrfs_mark_buffer_dirty(trans, right);
3480 else
3481 btrfs_clear_buffer_dirty(trans, right);
3482
3483 btrfs_item_key(right, &disk_key, 0);
3484 fixup_low_keys(trans, path, &disk_key, 1);
3485
3486 /* then fixup the leaf pointer in the path */
3487 if (path->slots[0] < push_items) {
3488 path->slots[0] += old_left_nritems;
3489 btrfs_tree_unlock(path->nodes[0]);
3490 free_extent_buffer(path->nodes[0]);
3491 path->nodes[0] = left;
3492 path->slots[1] -= 1;
3493 } else {
3494 btrfs_tree_unlock(left);
3495 free_extent_buffer(left);
3496 path->slots[0] -= push_items;
3497 }
3498 BUG_ON(path->slots[0] < 0);
3499 return ret;
3500out:
3501 btrfs_tree_unlock(left);
3502 free_extent_buffer(left);
3503 return ret;
3504}
3505
3506/*
3507 * push some data in the path leaf to the left, trying to free up at
3508 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3509 *
3510 * max_slot can put a limit on how far into the leaf we'll push items. The
3511 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3512 * items
3513 */
3514static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3515 *root, struct btrfs_path *path, int min_data_size,
3516 int data_size, int empty, u32 max_slot)
3517{
3518 struct extent_buffer *right = path->nodes[0];
3519 struct extent_buffer *left;
3520 int slot;
3521 int free_space;
3522 u32 right_nritems;
3523 int ret = 0;
3524
3525 slot = path->slots[1];
3526 if (slot == 0)
3527 return 1;
3528 if (!path->nodes[1])
3529 return 1;
3530
3531 right_nritems = btrfs_header_nritems(right);
3532 if (right_nritems == 0)
3533 return 1;
3534
3535 btrfs_assert_tree_write_locked(path->nodes[1]);
3536
3537 left = btrfs_read_node_slot(path->nodes[1], slot - 1);
3538 if (IS_ERR(left))
3539 return PTR_ERR(left);
3540
3541 btrfs_tree_lock_nested(left, BTRFS_NESTING_LEFT);
3542
3543 free_space = btrfs_leaf_free_space(left);
3544 if (free_space < data_size) {
3545 ret = 1;
3546 goto out;
3547 }
3548
3549 ret = btrfs_cow_block(trans, root, left,
3550 path->nodes[1], slot - 1, &left,
3551 BTRFS_NESTING_LEFT_COW);
3552 if (ret) {
3553 /* we hit -ENOSPC, but it isn't fatal here */
3554 if (ret == -ENOSPC)
3555 ret = 1;
3556 goto out;
3557 }
3558
3559 if (check_sibling_keys(left, right)) {
3560 ret = -EUCLEAN;
3561 btrfs_abort_transaction(trans, ret);
3562 goto out;
3563 }
3564 return __push_leaf_left(trans, path, min_data_size, empty, left,
3565 free_space, right_nritems, max_slot);
3566out:
3567 btrfs_tree_unlock(left);
3568 free_extent_buffer(left);
3569 return ret;
3570}
3571
3572/*
3573 * split the path's leaf in two, making sure there is at least data_size
3574 * available for the resulting leaf level of the path.
3575 */
3576static noinline int copy_for_split(struct btrfs_trans_handle *trans,
3577 struct btrfs_path *path,
3578 struct extent_buffer *l,
3579 struct extent_buffer *right,
3580 int slot, int mid, int nritems)
3581{
3582 struct btrfs_fs_info *fs_info = trans->fs_info;
3583 int data_copy_size;
3584 int rt_data_off;
3585 int i;
3586 int ret;
3587 struct btrfs_disk_key disk_key;
3588 struct btrfs_map_token token;
3589
3590 nritems = nritems - mid;
3591 btrfs_set_header_nritems(right, nritems);
3592 data_copy_size = btrfs_item_data_end(l, mid) - leaf_data_end(l);
3593
3594 copy_leaf_items(right, l, 0, mid, nritems);
3595
3596 copy_leaf_data(right, l, BTRFS_LEAF_DATA_SIZE(fs_info) - data_copy_size,
3597 leaf_data_end(l), data_copy_size);
3598
3599 rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_data_end(l, mid);
3600
3601 btrfs_init_map_token(&token, right);
3602 for (i = 0; i < nritems; i++) {
3603 u32 ioff;
3604
3605 ioff = btrfs_token_item_offset(&token, i);
3606 btrfs_set_token_item_offset(&token, i, ioff + rt_data_off);
3607 }
3608
3609 btrfs_set_header_nritems(l, mid);
3610 btrfs_item_key(right, &disk_key, 0);
3611 ret = insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
3612 if (ret < 0)
3613 return ret;
3614
3615 btrfs_mark_buffer_dirty(trans, right);
3616 btrfs_mark_buffer_dirty(trans, l);
3617 BUG_ON(path->slots[0] != slot);
3618
3619 if (mid <= slot) {
3620 btrfs_tree_unlock(path->nodes[0]);
3621 free_extent_buffer(path->nodes[0]);
3622 path->nodes[0] = right;
3623 path->slots[0] -= mid;
3624 path->slots[1] += 1;
3625 } else {
3626 btrfs_tree_unlock(right);
3627 free_extent_buffer(right);
3628 }
3629
3630 BUG_ON(path->slots[0] < 0);
3631
3632 return 0;
3633}
3634
3635/*
3636 * double splits happen when we need to insert a big item in the middle
3637 * of a leaf. A double split can leave us with 3 mostly empty leaves:
3638 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
3639 * A B C
3640 *
3641 * We avoid this by trying to push the items on either side of our target
3642 * into the adjacent leaves. If all goes well we can avoid the double split
3643 * completely.
3644 */
3645static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
3646 struct btrfs_root *root,
3647 struct btrfs_path *path,
3648 int data_size)
3649{
3650 int ret;
3651 int progress = 0;
3652 int slot;
3653 u32 nritems;
3654 int space_needed = data_size;
3655
3656 slot = path->slots[0];
3657 if (slot < btrfs_header_nritems(path->nodes[0]))
3658 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3659
3660 /*
3661 * try to push all the items after our slot into the
3662 * right leaf
3663 */
3664 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
3665 if (ret < 0)
3666 return ret;
3667
3668 if (ret == 0)
3669 progress++;
3670
3671 nritems = btrfs_header_nritems(path->nodes[0]);
3672 /*
3673 * our goal is to get our slot at the start or end of a leaf. If
3674 * we've done so we're done
3675 */
3676 if (path->slots[0] == 0 || path->slots[0] == nritems)
3677 return 0;
3678
3679 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3680 return 0;
3681
3682 /* try to push all the items before our slot into the next leaf */
3683 slot = path->slots[0];
3684 space_needed = data_size;
3685 if (slot > 0)
3686 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3687 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
3688 if (ret < 0)
3689 return ret;
3690
3691 if (ret == 0)
3692 progress++;
3693
3694 if (progress)
3695 return 0;
3696 return 1;
3697}
3698
3699/*
3700 * split the path's leaf in two, making sure there is at least data_size
3701 * available for the resulting leaf level of the path.
3702 *
3703 * returns 0 if all went well and < 0 on failure.
3704 */
3705static noinline int split_leaf(struct btrfs_trans_handle *trans,
3706 struct btrfs_root *root,
3707 const struct btrfs_key *ins_key,
3708 struct btrfs_path *path, int data_size,
3709 int extend)
3710{
3711 struct btrfs_disk_key disk_key;
3712 struct extent_buffer *l;
3713 u32 nritems;
3714 int mid;
3715 int slot;
3716 struct extent_buffer *right;
3717 struct btrfs_fs_info *fs_info = root->fs_info;
3718 int ret = 0;
3719 int wret;
3720 int split;
3721 int num_doubles = 0;
3722 int tried_avoid_double = 0;
3723
3724 l = path->nodes[0];
3725 slot = path->slots[0];
3726 if (extend && data_size + btrfs_item_size(l, slot) +
3727 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
3728 return -EOVERFLOW;
3729
3730 /* first try to make some room by pushing left and right */
3731 if (data_size && path->nodes[1]) {
3732 int space_needed = data_size;
3733
3734 if (slot < btrfs_header_nritems(l))
3735 space_needed -= btrfs_leaf_free_space(l);
3736
3737 wret = push_leaf_right(trans, root, path, space_needed,
3738 space_needed, 0, 0);
3739 if (wret < 0)
3740 return wret;
3741 if (wret) {
3742 space_needed = data_size;
3743 if (slot > 0)
3744 space_needed -= btrfs_leaf_free_space(l);
3745 wret = push_leaf_left(trans, root, path, space_needed,
3746 space_needed, 0, (u32)-1);
3747 if (wret < 0)
3748 return wret;
3749 }
3750 l = path->nodes[0];
3751
3752 /* did the pushes work? */
3753 if (btrfs_leaf_free_space(l) >= data_size)
3754 return 0;
3755 }
3756
3757 if (!path->nodes[1]) {
3758 ret = insert_new_root(trans, root, path, 1);
3759 if (ret)
3760 return ret;
3761 }
3762again:
3763 split = 1;
3764 l = path->nodes[0];
3765 slot = path->slots[0];
3766 nritems = btrfs_header_nritems(l);
3767 mid = (nritems + 1) / 2;
3768
3769 if (mid <= slot) {
3770 if (nritems == 1 ||
3771 leaf_space_used(l, mid, nritems - mid) + data_size >
3772 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3773 if (slot >= nritems) {
3774 split = 0;
3775 } else {
3776 mid = slot;
3777 if (mid != nritems &&
3778 leaf_space_used(l, mid, nritems - mid) +
3779 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3780 if (data_size && !tried_avoid_double)
3781 goto push_for_double;
3782 split = 2;
3783 }
3784 }
3785 }
3786 } else {
3787 if (leaf_space_used(l, 0, mid) + data_size >
3788 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3789 if (!extend && data_size && slot == 0) {
3790 split = 0;
3791 } else if ((extend || !data_size) && slot == 0) {
3792 mid = 1;
3793 } else {
3794 mid = slot;
3795 if (mid != nritems &&
3796 leaf_space_used(l, mid, nritems - mid) +
3797 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3798 if (data_size && !tried_avoid_double)
3799 goto push_for_double;
3800 split = 2;
3801 }
3802 }
3803 }
3804 }
3805
3806 if (split == 0)
3807 btrfs_cpu_key_to_disk(&disk_key, ins_key);
3808 else
3809 btrfs_item_key(l, &disk_key, mid);
3810
3811 /*
3812 * We have to about BTRFS_NESTING_NEW_ROOT here if we've done a double
3813 * split, because we're only allowed to have MAX_LOCKDEP_SUBCLASSES
3814 * subclasses, which is 8 at the time of this patch, and we've maxed it
3815 * out. In the future we could add a
3816 * BTRFS_NESTING_SPLIT_THE_SPLITTENING if we need to, but for now just
3817 * use BTRFS_NESTING_NEW_ROOT.
3818 */
3819 right = btrfs_alloc_tree_block(trans, root, 0, btrfs_root_id(root),
3820 &disk_key, 0, l->start, 0, 0,
3821 num_doubles ? BTRFS_NESTING_NEW_ROOT :
3822 BTRFS_NESTING_SPLIT);
3823 if (IS_ERR(right))
3824 return PTR_ERR(right);
3825
3826 root_add_used_bytes(root);
3827
3828 if (split == 0) {
3829 if (mid <= slot) {
3830 btrfs_set_header_nritems(right, 0);
3831 ret = insert_ptr(trans, path, &disk_key,
3832 right->start, path->slots[1] + 1, 1);
3833 if (ret < 0) {
3834 btrfs_tree_unlock(right);
3835 free_extent_buffer(right);
3836 return ret;
3837 }
3838 btrfs_tree_unlock(path->nodes[0]);
3839 free_extent_buffer(path->nodes[0]);
3840 path->nodes[0] = right;
3841 path->slots[0] = 0;
3842 path->slots[1] += 1;
3843 } else {
3844 btrfs_set_header_nritems(right, 0);
3845 ret = insert_ptr(trans, path, &disk_key,
3846 right->start, path->slots[1], 1);
3847 if (ret < 0) {
3848 btrfs_tree_unlock(right);
3849 free_extent_buffer(right);
3850 return ret;
3851 }
3852 btrfs_tree_unlock(path->nodes[0]);
3853 free_extent_buffer(path->nodes[0]);
3854 path->nodes[0] = right;
3855 path->slots[0] = 0;
3856 if (path->slots[1] == 0)
3857 fixup_low_keys(trans, path, &disk_key, 1);
3858 }
3859 /*
3860 * We create a new leaf 'right' for the required ins_len and
3861 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
3862 * the content of ins_len to 'right'.
3863 */
3864 return ret;
3865 }
3866
3867 ret = copy_for_split(trans, path, l, right, slot, mid, nritems);
3868 if (ret < 0) {
3869 btrfs_tree_unlock(right);
3870 free_extent_buffer(right);
3871 return ret;
3872 }
3873
3874 if (split == 2) {
3875 BUG_ON(num_doubles != 0);
3876 num_doubles++;
3877 goto again;
3878 }
3879
3880 return 0;
3881
3882push_for_double:
3883 push_for_double_split(trans, root, path, data_size);
3884 tried_avoid_double = 1;
3885 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3886 return 0;
3887 goto again;
3888}
3889
3890static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3891 struct btrfs_root *root,
3892 struct btrfs_path *path, int ins_len)
3893{
3894 struct btrfs_key key;
3895 struct extent_buffer *leaf;
3896 struct btrfs_file_extent_item *fi;
3897 u64 extent_len = 0;
3898 u32 item_size;
3899 int ret;
3900
3901 leaf = path->nodes[0];
3902 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3903
3904 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3905 key.type != BTRFS_EXTENT_CSUM_KEY);
3906
3907 if (btrfs_leaf_free_space(leaf) >= ins_len)
3908 return 0;
3909
3910 item_size = btrfs_item_size(leaf, path->slots[0]);
3911 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3912 fi = btrfs_item_ptr(leaf, path->slots[0],
3913 struct btrfs_file_extent_item);
3914 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3915 }
3916 btrfs_release_path(path);
3917
3918 path->keep_locks = 1;
3919 path->search_for_split = 1;
3920 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3921 path->search_for_split = 0;
3922 if (ret > 0)
3923 ret = -EAGAIN;
3924 if (ret < 0)
3925 goto err;
3926
3927 ret = -EAGAIN;
3928 leaf = path->nodes[0];
3929 /* if our item isn't there, return now */
3930 if (item_size != btrfs_item_size(leaf, path->slots[0]))
3931 goto err;
3932
3933 /* the leaf has changed, it now has room. return now */
3934 if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
3935 goto err;
3936
3937 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3938 fi = btrfs_item_ptr(leaf, path->slots[0],
3939 struct btrfs_file_extent_item);
3940 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3941 goto err;
3942 }
3943
3944 ret = split_leaf(trans, root, &key, path, ins_len, 1);
3945 if (ret)
3946 goto err;
3947
3948 path->keep_locks = 0;
3949 btrfs_unlock_up_safe(path, 1);
3950 return 0;
3951err:
3952 path->keep_locks = 0;
3953 return ret;
3954}
3955
3956static noinline int split_item(struct btrfs_trans_handle *trans,
3957 struct btrfs_path *path,
3958 const struct btrfs_key *new_key,
3959 unsigned long split_offset)
3960{
3961 struct extent_buffer *leaf;
3962 int orig_slot, slot;
3963 char *buf;
3964 u32 nritems;
3965 u32 item_size;
3966 u32 orig_offset;
3967 struct btrfs_disk_key disk_key;
3968
3969 leaf = path->nodes[0];
3970 /*
3971 * Shouldn't happen because the caller must have previously called
3972 * setup_leaf_for_split() to make room for the new item in the leaf.
3973 */
3974 if (WARN_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item)))
3975 return -ENOSPC;
3976
3977 orig_slot = path->slots[0];
3978 orig_offset = btrfs_item_offset(leaf, path->slots[0]);
3979 item_size = btrfs_item_size(leaf, path->slots[0]);
3980
3981 buf = kmalloc(item_size, GFP_NOFS);
3982 if (!buf)
3983 return -ENOMEM;
3984
3985 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3986 path->slots[0]), item_size);
3987
3988 slot = path->slots[0] + 1;
3989 nritems = btrfs_header_nritems(leaf);
3990 if (slot != nritems) {
3991 /* shift the items */
3992 memmove_leaf_items(leaf, slot + 1, slot, nritems - slot);
3993 }
3994
3995 btrfs_cpu_key_to_disk(&disk_key, new_key);
3996 btrfs_set_item_key(leaf, &disk_key, slot);
3997
3998 btrfs_set_item_offset(leaf, slot, orig_offset);
3999 btrfs_set_item_size(leaf, slot, item_size - split_offset);
4000
4001 btrfs_set_item_offset(leaf, orig_slot,
4002 orig_offset + item_size - split_offset);
4003 btrfs_set_item_size(leaf, orig_slot, split_offset);
4004
4005 btrfs_set_header_nritems(leaf, nritems + 1);
4006
4007 /* write the data for the start of the original item */
4008 write_extent_buffer(leaf, buf,
4009 btrfs_item_ptr_offset(leaf, path->slots[0]),
4010 split_offset);
4011
4012 /* write the data for the new item */
4013 write_extent_buffer(leaf, buf + split_offset,
4014 btrfs_item_ptr_offset(leaf, slot),
4015 item_size - split_offset);
4016 btrfs_mark_buffer_dirty(trans, leaf);
4017
4018 BUG_ON(btrfs_leaf_free_space(leaf) < 0);
4019 kfree(buf);
4020 return 0;
4021}
4022
4023/*
4024 * This function splits a single item into two items,
4025 * giving 'new_key' to the new item and splitting the
4026 * old one at split_offset (from the start of the item).
4027 *
4028 * The path may be released by this operation. After
4029 * the split, the path is pointing to the old item. The
4030 * new item is going to be in the same node as the old one.
4031 *
4032 * Note, the item being split must be smaller enough to live alone on
4033 * a tree block with room for one extra struct btrfs_item
4034 *
4035 * This allows us to split the item in place, keeping a lock on the
4036 * leaf the entire time.
4037 */
4038int btrfs_split_item(struct btrfs_trans_handle *trans,
4039 struct btrfs_root *root,
4040 struct btrfs_path *path,
4041 const struct btrfs_key *new_key,
4042 unsigned long split_offset)
4043{
4044 int ret;
4045 ret = setup_leaf_for_split(trans, root, path,
4046 sizeof(struct btrfs_item));
4047 if (ret)
4048 return ret;
4049
4050 ret = split_item(trans, path, new_key, split_offset);
4051 return ret;
4052}
4053
4054/*
4055 * make the item pointed to by the path smaller. new_size indicates
4056 * how small to make it, and from_end tells us if we just chop bytes
4057 * off the end of the item or if we shift the item to chop bytes off
4058 * the front.
4059 */
4060void btrfs_truncate_item(struct btrfs_trans_handle *trans,
4061 const struct btrfs_path *path, u32 new_size, int from_end)
4062{
4063 int slot;
4064 struct extent_buffer *leaf;
4065 u32 nritems;
4066 unsigned int data_end;
4067 unsigned int old_data_start;
4068 unsigned int old_size;
4069 unsigned int size_diff;
4070 int i;
4071 struct btrfs_map_token token;
4072
4073 leaf = path->nodes[0];
4074 slot = path->slots[0];
4075
4076 old_size = btrfs_item_size(leaf, slot);
4077 if (old_size == new_size)
4078 return;
4079
4080 nritems = btrfs_header_nritems(leaf);
4081 data_end = leaf_data_end(leaf);
4082
4083 old_data_start = btrfs_item_offset(leaf, slot);
4084
4085 size_diff = old_size - new_size;
4086
4087 BUG_ON(slot < 0);
4088 BUG_ON(slot >= nritems);
4089
4090 /*
4091 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4092 */
4093 /* first correct the data pointers */
4094 btrfs_init_map_token(&token, leaf);
4095 for (i = slot; i < nritems; i++) {
4096 u32 ioff;
4097
4098 ioff = btrfs_token_item_offset(&token, i);
4099 btrfs_set_token_item_offset(&token, i, ioff + size_diff);
4100 }
4101
4102 /* shift the data */
4103 if (from_end) {
4104 memmove_leaf_data(leaf, data_end + size_diff, data_end,
4105 old_data_start + new_size - data_end);
4106 } else {
4107 struct btrfs_disk_key disk_key;
4108 u64 offset;
4109
4110 btrfs_item_key(leaf, &disk_key, slot);
4111
4112 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4113 unsigned long ptr;
4114 struct btrfs_file_extent_item *fi;
4115
4116 fi = btrfs_item_ptr(leaf, slot,
4117 struct btrfs_file_extent_item);
4118 fi = (struct btrfs_file_extent_item *)(
4119 (unsigned long)fi - size_diff);
4120
4121 if (btrfs_file_extent_type(leaf, fi) ==
4122 BTRFS_FILE_EXTENT_INLINE) {
4123 ptr = btrfs_item_ptr_offset(leaf, slot);
4124 memmove_extent_buffer(leaf, ptr,
4125 (unsigned long)fi,
4126 BTRFS_FILE_EXTENT_INLINE_DATA_START);
4127 }
4128 }
4129
4130 memmove_leaf_data(leaf, data_end + size_diff, data_end,
4131 old_data_start - data_end);
4132
4133 offset = btrfs_disk_key_offset(&disk_key);
4134 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4135 btrfs_set_item_key(leaf, &disk_key, slot);
4136 if (slot == 0)
4137 fixup_low_keys(trans, path, &disk_key, 1);
4138 }
4139
4140 btrfs_set_item_size(leaf, slot, new_size);
4141 btrfs_mark_buffer_dirty(trans, leaf);
4142
4143 if (btrfs_leaf_free_space(leaf) < 0) {
4144 btrfs_print_leaf(leaf);
4145 BUG();
4146 }
4147}
4148
4149/*
4150 * make the item pointed to by the path bigger, data_size is the added size.
4151 */
4152void btrfs_extend_item(struct btrfs_trans_handle *trans,
4153 const struct btrfs_path *path, u32 data_size)
4154{
4155 int slot;
4156 struct extent_buffer *leaf;
4157 u32 nritems;
4158 unsigned int data_end;
4159 unsigned int old_data;
4160 unsigned int old_size;
4161 int i;
4162 struct btrfs_map_token token;
4163
4164 leaf = path->nodes[0];
4165
4166 nritems = btrfs_header_nritems(leaf);
4167 data_end = leaf_data_end(leaf);
4168
4169 if (btrfs_leaf_free_space(leaf) < data_size) {
4170 btrfs_print_leaf(leaf);
4171 BUG();
4172 }
4173 slot = path->slots[0];
4174 old_data = btrfs_item_data_end(leaf, slot);
4175
4176 BUG_ON(slot < 0);
4177 if (slot >= nritems) {
4178 btrfs_print_leaf(leaf);
4179 btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
4180 slot, nritems);
4181 BUG();
4182 }
4183
4184 /*
4185 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4186 */
4187 /* first correct the data pointers */
4188 btrfs_init_map_token(&token, leaf);
4189 for (i = slot; i < nritems; i++) {
4190 u32 ioff;
4191
4192 ioff = btrfs_token_item_offset(&token, i);
4193 btrfs_set_token_item_offset(&token, i, ioff - data_size);
4194 }
4195
4196 /* shift the data */
4197 memmove_leaf_data(leaf, data_end - data_size, data_end,
4198 old_data - data_end);
4199
4200 data_end = old_data;
4201 old_size = btrfs_item_size(leaf, slot);
4202 btrfs_set_item_size(leaf, slot, old_size + data_size);
4203 btrfs_mark_buffer_dirty(trans, leaf);
4204
4205 if (btrfs_leaf_free_space(leaf) < 0) {
4206 btrfs_print_leaf(leaf);
4207 BUG();
4208 }
4209}
4210
4211/*
4212 * Make space in the node before inserting one or more items.
4213 *
4214 * @trans: transaction handle
4215 * @root: root we are inserting items to
4216 * @path: points to the leaf/slot where we are going to insert new items
4217 * @batch: information about the batch of items to insert
4218 *
4219 * Main purpose is to save stack depth by doing the bulk of the work in a
4220 * function that doesn't call btrfs_search_slot
4221 */
4222static void setup_items_for_insert(struct btrfs_trans_handle *trans,
4223 struct btrfs_root *root, struct btrfs_path *path,
4224 const struct btrfs_item_batch *batch)
4225{
4226 struct btrfs_fs_info *fs_info = root->fs_info;
4227 int i;
4228 u32 nritems;
4229 unsigned int data_end;
4230 struct btrfs_disk_key disk_key;
4231 struct extent_buffer *leaf;
4232 int slot;
4233 struct btrfs_map_token token;
4234 u32 total_size;
4235
4236 /*
4237 * Before anything else, update keys in the parent and other ancestors
4238 * if needed, then release the write locks on them, so that other tasks
4239 * can use them while we modify the leaf.
4240 */
4241 if (path->slots[0] == 0) {
4242 btrfs_cpu_key_to_disk(&disk_key, &batch->keys[0]);
4243 fixup_low_keys(trans, path, &disk_key, 1);
4244 }
4245 btrfs_unlock_up_safe(path, 1);
4246
4247 leaf = path->nodes[0];
4248 slot = path->slots[0];
4249
4250 nritems = btrfs_header_nritems(leaf);
4251 data_end = leaf_data_end(leaf);
4252 total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
4253
4254 if (btrfs_leaf_free_space(leaf) < total_size) {
4255 btrfs_print_leaf(leaf);
4256 btrfs_crit(fs_info, "not enough freespace need %u have %d",
4257 total_size, btrfs_leaf_free_space(leaf));
4258 BUG();
4259 }
4260
4261 btrfs_init_map_token(&token, leaf);
4262 if (slot != nritems) {
4263 unsigned int old_data = btrfs_item_data_end(leaf, slot);
4264
4265 if (old_data < data_end) {
4266 btrfs_print_leaf(leaf);
4267 btrfs_crit(fs_info,
4268 "item at slot %d with data offset %u beyond data end of leaf %u",
4269 slot, old_data, data_end);
4270 BUG();
4271 }
4272 /*
4273 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4274 */
4275 /* first correct the data pointers */
4276 for (i = slot; i < nritems; i++) {
4277 u32 ioff;
4278
4279 ioff = btrfs_token_item_offset(&token, i);
4280 btrfs_set_token_item_offset(&token, i,
4281 ioff - batch->total_data_size);
4282 }
4283 /* shift the items */
4284 memmove_leaf_items(leaf, slot + batch->nr, slot, nritems - slot);
4285
4286 /* shift the data */
4287 memmove_leaf_data(leaf, data_end - batch->total_data_size,
4288 data_end, old_data - data_end);
4289 data_end = old_data;
4290 }
4291
4292 /* setup the item for the new data */
4293 for (i = 0; i < batch->nr; i++) {
4294 btrfs_cpu_key_to_disk(&disk_key, &batch->keys[i]);
4295 btrfs_set_item_key(leaf, &disk_key, slot + i);
4296 data_end -= batch->data_sizes[i];
4297 btrfs_set_token_item_offset(&token, slot + i, data_end);
4298 btrfs_set_token_item_size(&token, slot + i, batch->data_sizes[i]);
4299 }
4300
4301 btrfs_set_header_nritems(leaf, nritems + batch->nr);
4302 btrfs_mark_buffer_dirty(trans, leaf);
4303
4304 if (btrfs_leaf_free_space(leaf) < 0) {
4305 btrfs_print_leaf(leaf);
4306 BUG();
4307 }
4308}
4309
4310/*
4311 * Insert a new item into a leaf.
4312 *
4313 * @trans: Transaction handle.
4314 * @root: The root of the btree.
4315 * @path: A path pointing to the target leaf and slot.
4316 * @key: The key of the new item.
4317 * @data_size: The size of the data associated with the new key.
4318 */
4319void btrfs_setup_item_for_insert(struct btrfs_trans_handle *trans,
4320 struct btrfs_root *root,
4321 struct btrfs_path *path,
4322 const struct btrfs_key *key,
4323 u32 data_size)
4324{
4325 struct btrfs_item_batch batch;
4326
4327 batch.keys = key;
4328 batch.data_sizes = &data_size;
4329 batch.total_data_size = data_size;
4330 batch.nr = 1;
4331
4332 setup_items_for_insert(trans, root, path, &batch);
4333}
4334
4335/*
4336 * Given a key and some data, insert items into the tree.
4337 * This does all the path init required, making room in the tree if needed.
4338 *
4339 * Returns: 0 on success
4340 * -EEXIST if the first key already exists
4341 * < 0 on other errors
4342 */
4343int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4344 struct btrfs_root *root,
4345 struct btrfs_path *path,
4346 const struct btrfs_item_batch *batch)
4347{
4348 int ret = 0;
4349 int slot;
4350 u32 total_size;
4351
4352 total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
4353 ret = btrfs_search_slot(trans, root, &batch->keys[0], path, total_size, 1);
4354 if (ret == 0)
4355 return -EEXIST;
4356 if (ret < 0)
4357 return ret;
4358
4359 slot = path->slots[0];
4360 BUG_ON(slot < 0);
4361
4362 setup_items_for_insert(trans, root, path, batch);
4363 return 0;
4364}
4365
4366/*
4367 * Given a key and some data, insert an item into the tree.
4368 * This does all the path init required, making room in the tree if needed.
4369 */
4370int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4371 const struct btrfs_key *cpu_key, void *data,
4372 u32 data_size)
4373{
4374 int ret = 0;
4375 struct btrfs_path *path;
4376 struct extent_buffer *leaf;
4377 unsigned long ptr;
4378
4379 path = btrfs_alloc_path();
4380 if (!path)
4381 return -ENOMEM;
4382 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4383 if (!ret) {
4384 leaf = path->nodes[0];
4385 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4386 write_extent_buffer(leaf, data, ptr, data_size);
4387 btrfs_mark_buffer_dirty(trans, leaf);
4388 }
4389 btrfs_free_path(path);
4390 return ret;
4391}
4392
4393/*
4394 * This function duplicates an item, giving 'new_key' to the new item.
4395 * It guarantees both items live in the same tree leaf and the new item is
4396 * contiguous with the original item.
4397 *
4398 * This allows us to split a file extent in place, keeping a lock on the leaf
4399 * the entire time.
4400 */
4401int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4402 struct btrfs_root *root,
4403 struct btrfs_path *path,
4404 const struct btrfs_key *new_key)
4405{
4406 struct extent_buffer *leaf;
4407 int ret;
4408 u32 item_size;
4409
4410 leaf = path->nodes[0];
4411 item_size = btrfs_item_size(leaf, path->slots[0]);
4412 ret = setup_leaf_for_split(trans, root, path,
4413 item_size + sizeof(struct btrfs_item));
4414 if (ret)
4415 return ret;
4416
4417 path->slots[0]++;
4418 btrfs_setup_item_for_insert(trans, root, path, new_key, item_size);
4419 leaf = path->nodes[0];
4420 memcpy_extent_buffer(leaf,
4421 btrfs_item_ptr_offset(leaf, path->slots[0]),
4422 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4423 item_size);
4424 return 0;
4425}
4426
4427/*
4428 * delete the pointer from a given node.
4429 *
4430 * the tree should have been previously balanced so the deletion does not
4431 * empty a node.
4432 *
4433 * This is exported for use inside btrfs-progs, don't un-export it.
4434 */
4435int btrfs_del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4436 struct btrfs_path *path, int level, int slot)
4437{
4438 struct extent_buffer *parent = path->nodes[level];
4439 u32 nritems;
4440 int ret;
4441
4442 nritems = btrfs_header_nritems(parent);
4443 if (slot != nritems - 1) {
4444 if (level) {
4445 ret = btrfs_tree_mod_log_insert_move(parent, slot,
4446 slot + 1, nritems - slot - 1);
4447 if (ret < 0) {
4448 btrfs_abort_transaction(trans, ret);
4449 return ret;
4450 }
4451 }
4452 memmove_extent_buffer(parent,
4453 btrfs_node_key_ptr_offset(parent, slot),
4454 btrfs_node_key_ptr_offset(parent, slot + 1),
4455 sizeof(struct btrfs_key_ptr) *
4456 (nritems - slot - 1));
4457 } else if (level) {
4458 ret = btrfs_tree_mod_log_insert_key(parent, slot,
4459 BTRFS_MOD_LOG_KEY_REMOVE);
4460 if (ret < 0) {
4461 btrfs_abort_transaction(trans, ret);
4462 return ret;
4463 }
4464 }
4465
4466 nritems--;
4467 btrfs_set_header_nritems(parent, nritems);
4468 if (nritems == 0 && parent == root->node) {
4469 BUG_ON(btrfs_header_level(root->node) != 1);
4470 /* just turn the root into a leaf and break */
4471 btrfs_set_header_level(root->node, 0);
4472 } else if (slot == 0) {
4473 struct btrfs_disk_key disk_key;
4474
4475 btrfs_node_key(parent, &disk_key, 0);
4476 fixup_low_keys(trans, path, &disk_key, level + 1);
4477 }
4478 btrfs_mark_buffer_dirty(trans, parent);
4479 return 0;
4480}
4481
4482/*
4483 * a helper function to delete the leaf pointed to by path->slots[1] and
4484 * path->nodes[1].
4485 *
4486 * This deletes the pointer in path->nodes[1] and frees the leaf
4487 * block extent. zero is returned if it all worked out, < 0 otherwise.
4488 *
4489 * The path must have already been setup for deleting the leaf, including
4490 * all the proper balancing. path->nodes[1] must be locked.
4491 */
4492static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
4493 struct btrfs_root *root,
4494 struct btrfs_path *path,
4495 struct extent_buffer *leaf)
4496{
4497 int ret;
4498
4499 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4500 ret = btrfs_del_ptr(trans, root, path, 1, path->slots[1]);
4501 if (ret < 0)
4502 return ret;
4503
4504 /*
4505 * btrfs_free_extent is expensive, we want to make sure we
4506 * aren't holding any locks when we call it
4507 */
4508 btrfs_unlock_up_safe(path, 0);
4509
4510 root_sub_used_bytes(root);
4511
4512 atomic_inc(&leaf->refs);
4513 ret = btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
4514 free_extent_buffer_stale(leaf);
4515 if (ret < 0)
4516 btrfs_abort_transaction(trans, ret);
4517
4518 return ret;
4519}
4520/*
4521 * delete the item at the leaf level in path. If that empties
4522 * the leaf, remove it from the tree
4523 */
4524int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4525 struct btrfs_path *path, int slot, int nr)
4526{
4527 struct btrfs_fs_info *fs_info = root->fs_info;
4528 struct extent_buffer *leaf;
4529 int ret = 0;
4530 int wret;
4531 u32 nritems;
4532
4533 leaf = path->nodes[0];
4534 nritems = btrfs_header_nritems(leaf);
4535
4536 if (slot + nr != nritems) {
4537 const u32 last_off = btrfs_item_offset(leaf, slot + nr - 1);
4538 const int data_end = leaf_data_end(leaf);
4539 struct btrfs_map_token token;
4540 u32 dsize = 0;
4541 int i;
4542
4543 for (i = 0; i < nr; i++)
4544 dsize += btrfs_item_size(leaf, slot + i);
4545
4546 memmove_leaf_data(leaf, data_end + dsize, data_end,
4547 last_off - data_end);
4548
4549 btrfs_init_map_token(&token, leaf);
4550 for (i = slot + nr; i < nritems; i++) {
4551 u32 ioff;
4552
4553 ioff = btrfs_token_item_offset(&token, i);
4554 btrfs_set_token_item_offset(&token, i, ioff + dsize);
4555 }
4556
4557 memmove_leaf_items(leaf, slot, slot + nr, nritems - slot - nr);
4558 }
4559 btrfs_set_header_nritems(leaf, nritems - nr);
4560 nritems -= nr;
4561
4562 /* delete the leaf if we've emptied it */
4563 if (nritems == 0) {
4564 if (leaf == root->node) {
4565 btrfs_set_header_level(leaf, 0);
4566 } else {
4567 btrfs_clear_buffer_dirty(trans, leaf);
4568 ret = btrfs_del_leaf(trans, root, path, leaf);
4569 if (ret < 0)
4570 return ret;
4571 }
4572 } else {
4573 int used = leaf_space_used(leaf, 0, nritems);
4574 if (slot == 0) {
4575 struct btrfs_disk_key disk_key;
4576
4577 btrfs_item_key(leaf, &disk_key, 0);
4578 fixup_low_keys(trans, path, &disk_key, 1);
4579 }
4580
4581 /*
4582 * Try to delete the leaf if it is mostly empty. We do this by
4583 * trying to move all its items into its left and right neighbours.
4584 * If we can't move all the items, then we don't delete it - it's
4585 * not ideal, but future insertions might fill the leaf with more
4586 * items, or items from other leaves might be moved later into our
4587 * leaf due to deletions on those leaves.
4588 */
4589 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
4590 u32 min_push_space;
4591
4592 /* push_leaf_left fixes the path.
4593 * make sure the path still points to our leaf
4594 * for possible call to btrfs_del_ptr below
4595 */
4596 slot = path->slots[1];
4597 atomic_inc(&leaf->refs);
4598 /*
4599 * We want to be able to at least push one item to the
4600 * left neighbour leaf, and that's the first item.
4601 */
4602 min_push_space = sizeof(struct btrfs_item) +
4603 btrfs_item_size(leaf, 0);
4604 wret = push_leaf_left(trans, root, path, 0,
4605 min_push_space, 1, (u32)-1);
4606 if (wret < 0 && wret != -ENOSPC)
4607 ret = wret;
4608
4609 if (path->nodes[0] == leaf &&
4610 btrfs_header_nritems(leaf)) {
4611 /*
4612 * If we were not able to push all items from our
4613 * leaf to its left neighbour, then attempt to
4614 * either push all the remaining items to the
4615 * right neighbour or none. There's no advantage
4616 * in pushing only some items, instead of all, as
4617 * it's pointless to end up with a leaf having
4618 * too few items while the neighbours can be full
4619 * or nearly full.
4620 */
4621 nritems = btrfs_header_nritems(leaf);
4622 min_push_space = leaf_space_used(leaf, 0, nritems);
4623 wret = push_leaf_right(trans, root, path, 0,
4624 min_push_space, 1, 0);
4625 if (wret < 0 && wret != -ENOSPC)
4626 ret = wret;
4627 }
4628
4629 if (btrfs_header_nritems(leaf) == 0) {
4630 path->slots[1] = slot;
4631 ret = btrfs_del_leaf(trans, root, path, leaf);
4632 if (ret < 0)
4633 return ret;
4634 free_extent_buffer(leaf);
4635 ret = 0;
4636 } else {
4637 /* if we're still in the path, make sure
4638 * we're dirty. Otherwise, one of the
4639 * push_leaf functions must have already
4640 * dirtied this buffer
4641 */
4642 if (path->nodes[0] == leaf)
4643 btrfs_mark_buffer_dirty(trans, leaf);
4644 free_extent_buffer(leaf);
4645 }
4646 } else {
4647 btrfs_mark_buffer_dirty(trans, leaf);
4648 }
4649 }
4650 return ret;
4651}
4652
4653/*
4654 * A helper function to walk down the tree starting at min_key, and looking
4655 * for nodes or leaves that are have a minimum transaction id.
4656 * This is used by the btree defrag code, and tree logging
4657 *
4658 * This does not cow, but it does stuff the starting key it finds back
4659 * into min_key, so you can call btrfs_search_slot with cow=1 on the
4660 * key and get a writable path.
4661 *
4662 * This honors path->lowest_level to prevent descent past a given level
4663 * of the tree.
4664 *
4665 * min_trans indicates the oldest transaction that you are interested
4666 * in walking through. Any nodes or leaves older than min_trans are
4667 * skipped over (without reading them).
4668 *
4669 * returns zero if something useful was found, < 0 on error and 1 if there
4670 * was nothing in the tree that matched the search criteria.
4671 */
4672int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4673 struct btrfs_path *path,
4674 u64 min_trans)
4675{
4676 struct extent_buffer *cur;
4677 struct btrfs_key found_key;
4678 int slot;
4679 int sret;
4680 u32 nritems;
4681 int level;
4682 int ret = 1;
4683 int keep_locks = path->keep_locks;
4684
4685 ASSERT(!path->nowait);
4686 path->keep_locks = 1;
4687again:
4688 cur = btrfs_read_lock_root_node(root);
4689 level = btrfs_header_level(cur);
4690 WARN_ON(path->nodes[level]);
4691 path->nodes[level] = cur;
4692 path->locks[level] = BTRFS_READ_LOCK;
4693
4694 if (btrfs_header_generation(cur) < min_trans) {
4695 ret = 1;
4696 goto out;
4697 }
4698 while (1) {
4699 nritems = btrfs_header_nritems(cur);
4700 level = btrfs_header_level(cur);
4701 sret = btrfs_bin_search(cur, 0, min_key, &slot);
4702 if (sret < 0) {
4703 ret = sret;
4704 goto out;
4705 }
4706
4707 /* at the lowest level, we're done, setup the path and exit */
4708 if (level == path->lowest_level) {
4709 if (slot >= nritems)
4710 goto find_next_key;
4711 ret = 0;
4712 path->slots[level] = slot;
4713 btrfs_item_key_to_cpu(cur, &found_key, slot);
4714 goto out;
4715 }
4716 if (sret && slot > 0)
4717 slot--;
4718 /*
4719 * check this node pointer against the min_trans parameters.
4720 * If it is too old, skip to the next one.
4721 */
4722 while (slot < nritems) {
4723 u64 gen;
4724
4725 gen = btrfs_node_ptr_generation(cur, slot);
4726 if (gen < min_trans) {
4727 slot++;
4728 continue;
4729 }
4730 break;
4731 }
4732find_next_key:
4733 /*
4734 * we didn't find a candidate key in this node, walk forward
4735 * and find another one
4736 */
4737 if (slot >= nritems) {
4738 path->slots[level] = slot;
4739 sret = btrfs_find_next_key(root, path, min_key, level,
4740 min_trans);
4741 if (sret == 0) {
4742 btrfs_release_path(path);
4743 goto again;
4744 } else {
4745 goto out;
4746 }
4747 }
4748 /* save our key for returning back */
4749 btrfs_node_key_to_cpu(cur, &found_key, slot);
4750 path->slots[level] = slot;
4751 if (level == path->lowest_level) {
4752 ret = 0;
4753 goto out;
4754 }
4755 cur = btrfs_read_node_slot(cur, slot);
4756 if (IS_ERR(cur)) {
4757 ret = PTR_ERR(cur);
4758 goto out;
4759 }
4760
4761 btrfs_tree_read_lock(cur);
4762
4763 path->locks[level - 1] = BTRFS_READ_LOCK;
4764 path->nodes[level - 1] = cur;
4765 unlock_up(path, level, 1, 0, NULL);
4766 }
4767out:
4768 path->keep_locks = keep_locks;
4769 if (ret == 0) {
4770 btrfs_unlock_up_safe(path, path->lowest_level + 1);
4771 memcpy(min_key, &found_key, sizeof(found_key));
4772 }
4773 return ret;
4774}
4775
4776/*
4777 * this is similar to btrfs_next_leaf, but does not try to preserve
4778 * and fixup the path. It looks for and returns the next key in the
4779 * tree based on the current path and the min_trans parameters.
4780 *
4781 * 0 is returned if another key is found, < 0 if there are any errors
4782 * and 1 is returned if there are no higher keys in the tree
4783 *
4784 * path->keep_locks should be set to 1 on the search made before
4785 * calling this function.
4786 */
4787int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4788 struct btrfs_key *key, int level, u64 min_trans)
4789{
4790 int slot;
4791 struct extent_buffer *c;
4792
4793 WARN_ON(!path->keep_locks && !path->skip_locking);
4794 while (level < BTRFS_MAX_LEVEL) {
4795 if (!path->nodes[level])
4796 return 1;
4797
4798 slot = path->slots[level] + 1;
4799 c = path->nodes[level];
4800next:
4801 if (slot >= btrfs_header_nritems(c)) {
4802 int ret;
4803 int orig_lowest;
4804 struct btrfs_key cur_key;
4805 if (level + 1 >= BTRFS_MAX_LEVEL ||
4806 !path->nodes[level + 1])
4807 return 1;
4808
4809 if (path->locks[level + 1] || path->skip_locking) {
4810 level++;
4811 continue;
4812 }
4813
4814 slot = btrfs_header_nritems(c) - 1;
4815 if (level == 0)
4816 btrfs_item_key_to_cpu(c, &cur_key, slot);
4817 else
4818 btrfs_node_key_to_cpu(c, &cur_key, slot);
4819
4820 orig_lowest = path->lowest_level;
4821 btrfs_release_path(path);
4822 path->lowest_level = level;
4823 ret = btrfs_search_slot(NULL, root, &cur_key, path,
4824 0, 0);
4825 path->lowest_level = orig_lowest;
4826 if (ret < 0)
4827 return ret;
4828
4829 c = path->nodes[level];
4830 slot = path->slots[level];
4831 if (ret == 0)
4832 slot++;
4833 goto next;
4834 }
4835
4836 if (level == 0)
4837 btrfs_item_key_to_cpu(c, key, slot);
4838 else {
4839 u64 gen = btrfs_node_ptr_generation(c, slot);
4840
4841 if (gen < min_trans) {
4842 slot++;
4843 goto next;
4844 }
4845 btrfs_node_key_to_cpu(c, key, slot);
4846 }
4847 return 0;
4848 }
4849 return 1;
4850}
4851
4852int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
4853 u64 time_seq)
4854{
4855 int slot;
4856 int level;
4857 struct extent_buffer *c;
4858 struct extent_buffer *next;
4859 struct btrfs_fs_info *fs_info = root->fs_info;
4860 struct btrfs_key key;
4861 bool need_commit_sem = false;
4862 u32 nritems;
4863 int ret;
4864 int i;
4865
4866 /*
4867 * The nowait semantics are used only for write paths, where we don't
4868 * use the tree mod log and sequence numbers.
4869 */
4870 if (time_seq)
4871 ASSERT(!path->nowait);
4872
4873 nritems = btrfs_header_nritems(path->nodes[0]);
4874 if (nritems == 0)
4875 return 1;
4876
4877 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
4878again:
4879 level = 1;
4880 next = NULL;
4881 btrfs_release_path(path);
4882
4883 path->keep_locks = 1;
4884
4885 if (time_seq) {
4886 ret = btrfs_search_old_slot(root, &key, path, time_seq);
4887 } else {
4888 if (path->need_commit_sem) {
4889 path->need_commit_sem = 0;
4890 need_commit_sem = true;
4891 if (path->nowait) {
4892 if (!down_read_trylock(&fs_info->commit_root_sem)) {
4893 ret = -EAGAIN;
4894 goto done;
4895 }
4896 } else {
4897 down_read(&fs_info->commit_root_sem);
4898 }
4899 }
4900 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4901 }
4902 path->keep_locks = 0;
4903
4904 if (ret < 0)
4905 goto done;
4906
4907 nritems = btrfs_header_nritems(path->nodes[0]);
4908 /*
4909 * by releasing the path above we dropped all our locks. A balance
4910 * could have added more items next to the key that used to be
4911 * at the very end of the block. So, check again here and
4912 * advance the path if there are now more items available.
4913 */
4914 if (nritems > 0 && path->slots[0] < nritems - 1) {
4915 if (ret == 0)
4916 path->slots[0]++;
4917 ret = 0;
4918 goto done;
4919 }
4920 /*
4921 * So the above check misses one case:
4922 * - after releasing the path above, someone has removed the item that
4923 * used to be at the very end of the block, and balance between leafs
4924 * gets another one with bigger key.offset to replace it.
4925 *
4926 * This one should be returned as well, or we can get leaf corruption
4927 * later(esp. in __btrfs_drop_extents()).
4928 *
4929 * And a bit more explanation about this check,
4930 * with ret > 0, the key isn't found, the path points to the slot
4931 * where it should be inserted, so the path->slots[0] item must be the
4932 * bigger one.
4933 */
4934 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
4935 ret = 0;
4936 goto done;
4937 }
4938
4939 while (level < BTRFS_MAX_LEVEL) {
4940 if (!path->nodes[level]) {
4941 ret = 1;
4942 goto done;
4943 }
4944
4945 slot = path->slots[level] + 1;
4946 c = path->nodes[level];
4947 if (slot >= btrfs_header_nritems(c)) {
4948 level++;
4949 if (level == BTRFS_MAX_LEVEL) {
4950 ret = 1;
4951 goto done;
4952 }
4953 continue;
4954 }
4955
4956
4957 /*
4958 * Our current level is where we're going to start from, and to
4959 * make sure lockdep doesn't complain we need to drop our locks
4960 * and nodes from 0 to our current level.
4961 */
4962 for (i = 0; i < level; i++) {
4963 if (path->locks[level]) {
4964 btrfs_tree_read_unlock(path->nodes[i]);
4965 path->locks[i] = 0;
4966 }
4967 free_extent_buffer(path->nodes[i]);
4968 path->nodes[i] = NULL;
4969 }
4970
4971 next = c;
4972 ret = read_block_for_search(root, path, &next, slot, &key);
4973 if (ret == -EAGAIN && !path->nowait)
4974 goto again;
4975
4976 if (ret < 0) {
4977 btrfs_release_path(path);
4978 goto done;
4979 }
4980
4981 if (!path->skip_locking) {
4982 ret = btrfs_try_tree_read_lock(next);
4983 if (!ret && path->nowait) {
4984 ret = -EAGAIN;
4985 goto done;
4986 }
4987 if (!ret && time_seq) {
4988 /*
4989 * If we don't get the lock, we may be racing
4990 * with push_leaf_left, holding that lock while
4991 * itself waiting for the leaf we've currently
4992 * locked. To solve this situation, we give up
4993 * on our lock and cycle.
4994 */
4995 free_extent_buffer(next);
4996 btrfs_release_path(path);
4997 cond_resched();
4998 goto again;
4999 }
5000 if (!ret)
5001 btrfs_tree_read_lock(next);
5002 }
5003 break;
5004 }
5005 path->slots[level] = slot;
5006 while (1) {
5007 level--;
5008 path->nodes[level] = next;
5009 path->slots[level] = 0;
5010 if (!path->skip_locking)
5011 path->locks[level] = BTRFS_READ_LOCK;
5012 if (!level)
5013 break;
5014
5015 ret = read_block_for_search(root, path, &next, 0, &key);
5016 if (ret == -EAGAIN && !path->nowait)
5017 goto again;
5018
5019 if (ret < 0) {
5020 btrfs_release_path(path);
5021 goto done;
5022 }
5023
5024 if (!path->skip_locking) {
5025 if (path->nowait) {
5026 if (!btrfs_try_tree_read_lock(next)) {
5027 ret = -EAGAIN;
5028 goto done;
5029 }
5030 } else {
5031 btrfs_tree_read_lock(next);
5032 }
5033 }
5034 }
5035 ret = 0;
5036done:
5037 unlock_up(path, 0, 1, 0, NULL);
5038 if (need_commit_sem) {
5039 int ret2;
5040
5041 path->need_commit_sem = 1;
5042 ret2 = finish_need_commit_sem_search(path);
5043 up_read(&fs_info->commit_root_sem);
5044 if (ret2)
5045 ret = ret2;
5046 }
5047
5048 return ret;
5049}
5050
5051int btrfs_next_old_item(struct btrfs_root *root, struct btrfs_path *path, u64 time_seq)
5052{
5053 path->slots[0]++;
5054 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
5055 return btrfs_next_old_leaf(root, path, time_seq);
5056 return 0;
5057}
5058
5059/*
5060 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5061 * searching until it gets past min_objectid or finds an item of 'type'
5062 *
5063 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5064 */
5065int btrfs_previous_item(struct btrfs_root *root,
5066 struct btrfs_path *path, u64 min_objectid,
5067 int type)
5068{
5069 struct btrfs_key found_key;
5070 struct extent_buffer *leaf;
5071 u32 nritems;
5072 int ret;
5073
5074 while (1) {
5075 if (path->slots[0] == 0) {
5076 ret = btrfs_prev_leaf(root, path);
5077 if (ret != 0)
5078 return ret;
5079 } else {
5080 path->slots[0]--;
5081 }
5082 leaf = path->nodes[0];
5083 nritems = btrfs_header_nritems(leaf);
5084 if (nritems == 0)
5085 return 1;
5086 if (path->slots[0] == nritems)
5087 path->slots[0]--;
5088
5089 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5090 if (found_key.objectid < min_objectid)
5091 break;
5092 if (found_key.type == type)
5093 return 0;
5094 if (found_key.objectid == min_objectid &&
5095 found_key.type < type)
5096 break;
5097 }
5098 return 1;
5099}
5100
5101/*
5102 * search in extent tree to find a previous Metadata/Data extent item with
5103 * min objecitd.
5104 *
5105 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5106 */
5107int btrfs_previous_extent_item(struct btrfs_root *root,
5108 struct btrfs_path *path, u64 min_objectid)
5109{
5110 struct btrfs_key found_key;
5111 struct extent_buffer *leaf;
5112 u32 nritems;
5113 int ret;
5114
5115 while (1) {
5116 if (path->slots[0] == 0) {
5117 ret = btrfs_prev_leaf(root, path);
5118 if (ret != 0)
5119 return ret;
5120 } else {
5121 path->slots[0]--;
5122 }
5123 leaf = path->nodes[0];
5124 nritems = btrfs_header_nritems(leaf);
5125 if (nritems == 0)
5126 return 1;
5127 if (path->slots[0] == nritems)
5128 path->slots[0]--;
5129
5130 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5131 if (found_key.objectid < min_objectid)
5132 break;
5133 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5134 found_key.type == BTRFS_METADATA_ITEM_KEY)
5135 return 0;
5136 if (found_key.objectid == min_objectid &&
5137 found_key.type < BTRFS_EXTENT_ITEM_KEY)
5138 break;
5139 }
5140 return 1;
5141}
5142
5143int __init btrfs_ctree_init(void)
5144{
5145 btrfs_path_cachep = KMEM_CACHE(btrfs_path, 0);
5146 if (!btrfs_path_cachep)
5147 return -ENOMEM;
5148 return 0;
5149}
5150
5151void __cold btrfs_ctree_exit(void)
5152{
5153 kmem_cache_destroy(btrfs_path_cachep);
5154}
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}