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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007,2008 Oracle. All rights reserved.
4 */
5
6#include <linux/sched.h>
7#include <linux/slab.h>
8#include <linux/rbtree.h>
9#include <linux/mm.h>
10#include <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 (root->root_key.objectid == 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 != root->last_trans);
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 u64 new_flags = 0;
421 int ret;
422
423 /*
424 * Backrefs update rules:
425 *
426 * Always use full backrefs for extent pointers in tree block
427 * allocated by tree relocation.
428 *
429 * If a shared tree block is no longer referenced by its owner
430 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
431 * use full backrefs for extent pointers in tree block.
432 *
433 * If a tree block is been relocating
434 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
435 * use full backrefs for extent pointers in tree block.
436 * The reason for this is some operations (such as drop tree)
437 * are only allowed for blocks use full backrefs.
438 */
439
440 if (btrfs_block_can_be_shared(trans, root, buf)) {
441 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
442 btrfs_header_level(buf), 1,
443 &refs, &flags, NULL);
444 if (ret)
445 return ret;
446 if (unlikely(refs == 0)) {
447 btrfs_crit(fs_info,
448 "found 0 references for tree block at bytenr %llu level %d root %llu",
449 buf->start, btrfs_header_level(buf),
450 btrfs_root_id(root));
451 ret = -EUCLEAN;
452 btrfs_abort_transaction(trans, ret);
453 return ret;
454 }
455 } else {
456 refs = 1;
457 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
458 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
459 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
460 else
461 flags = 0;
462 }
463
464 owner = btrfs_header_owner(buf);
465 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
466 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
467
468 if (refs > 1) {
469 if ((owner == root->root_key.objectid ||
470 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
471 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
472 ret = btrfs_inc_ref(trans, root, buf, 1);
473 if (ret)
474 return ret;
475
476 if (root->root_key.objectid ==
477 BTRFS_TREE_RELOC_OBJECTID) {
478 ret = btrfs_dec_ref(trans, root, buf, 0);
479 if (ret)
480 return ret;
481 ret = btrfs_inc_ref(trans, root, cow, 1);
482 if (ret)
483 return ret;
484 }
485 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
486 } else {
487
488 if (root->root_key.objectid ==
489 BTRFS_TREE_RELOC_OBJECTID)
490 ret = btrfs_inc_ref(trans, root, cow, 1);
491 else
492 ret = btrfs_inc_ref(trans, root, cow, 0);
493 if (ret)
494 return ret;
495 }
496 if (new_flags != 0) {
497 ret = btrfs_set_disk_extent_flags(trans, buf, new_flags);
498 if (ret)
499 return ret;
500 }
501 } else {
502 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
503 if (root->root_key.objectid ==
504 BTRFS_TREE_RELOC_OBJECTID)
505 ret = btrfs_inc_ref(trans, root, cow, 1);
506 else
507 ret = btrfs_inc_ref(trans, root, cow, 0);
508 if (ret)
509 return ret;
510 ret = btrfs_dec_ref(trans, root, buf, 1);
511 if (ret)
512 return ret;
513 }
514 btrfs_clear_buffer_dirty(trans, buf);
515 *last_ref = 1;
516 }
517 return 0;
518}
519
520/*
521 * does the dirty work in cow of a single block. The parent block (if
522 * supplied) is updated to point to the new cow copy. The new buffer is marked
523 * dirty and returned locked. If you modify the block it needs to be marked
524 * dirty again.
525 *
526 * search_start -- an allocation hint for the new block
527 *
528 * empty_size -- a hint that you plan on doing more cow. This is the size in
529 * bytes the allocator should try to find free next to the block it returns.
530 * This is just a hint and may be ignored by the allocator.
531 */
532int btrfs_force_cow_block(struct btrfs_trans_handle *trans,
533 struct btrfs_root *root,
534 struct extent_buffer *buf,
535 struct extent_buffer *parent, int parent_slot,
536 struct extent_buffer **cow_ret,
537 u64 search_start, u64 empty_size,
538 enum btrfs_lock_nesting nest)
539{
540 struct btrfs_fs_info *fs_info = root->fs_info;
541 struct btrfs_disk_key disk_key;
542 struct extent_buffer *cow;
543 int level, ret;
544 int last_ref = 0;
545 int unlock_orig = 0;
546 u64 parent_start = 0;
547 u64 reloc_src_root = 0;
548
549 if (*cow_ret == buf)
550 unlock_orig = 1;
551
552 btrfs_assert_tree_write_locked(buf);
553
554 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
555 trans->transid != fs_info->running_transaction->transid);
556 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
557 trans->transid != root->last_trans);
558
559 level = btrfs_header_level(buf);
560
561 if (level == 0)
562 btrfs_item_key(buf, &disk_key, 0);
563 else
564 btrfs_node_key(buf, &disk_key, 0);
565
566 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
567 if (parent)
568 parent_start = parent->start;
569 reloc_src_root = btrfs_header_owner(buf);
570 }
571 cow = btrfs_alloc_tree_block(trans, root, parent_start,
572 root->root_key.objectid, &disk_key, level,
573 search_start, empty_size, reloc_src_root, nest);
574 if (IS_ERR(cow))
575 return PTR_ERR(cow);
576
577 /* cow is set to blocking by btrfs_init_new_buffer */
578
579 copy_extent_buffer_full(cow, buf);
580 btrfs_set_header_bytenr(cow, cow->start);
581 btrfs_set_header_generation(cow, trans->transid);
582 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
583 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
584 BTRFS_HEADER_FLAG_RELOC);
585 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
586 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
587 else
588 btrfs_set_header_owner(cow, root->root_key.objectid);
589
590 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
591
592 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
593 if (ret) {
594 btrfs_tree_unlock(cow);
595 free_extent_buffer(cow);
596 btrfs_abort_transaction(trans, ret);
597 return ret;
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_tree_unlock(cow);
604 free_extent_buffer(cow);
605 btrfs_abort_transaction(trans, ret);
606 return ret;
607 }
608 }
609
610 if (buf == root->node) {
611 WARN_ON(parent && parent != buf);
612 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
613 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
614 parent_start = buf->start;
615
616 ret = btrfs_tree_mod_log_insert_root(root->node, cow, true);
617 if (ret < 0) {
618 btrfs_tree_unlock(cow);
619 free_extent_buffer(cow);
620 btrfs_abort_transaction(trans, ret);
621 return ret;
622 }
623 atomic_inc(&cow->refs);
624 rcu_assign_pointer(root->node, cow);
625
626 btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
627 parent_start, last_ref);
628 free_extent_buffer(buf);
629 add_root_to_dirty_list(root);
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_tree_unlock(cow);
636 free_extent_buffer(cow);
637 btrfs_abort_transaction(trans, ret);
638 return ret;
639 }
640 btrfs_set_node_blockptr(parent, parent_slot,
641 cow->start);
642 btrfs_set_node_ptr_generation(parent, parent_slot,
643 trans->transid);
644 btrfs_mark_buffer_dirty(trans, parent);
645 if (last_ref) {
646 ret = btrfs_tree_mod_log_free_eb(buf);
647 if (ret) {
648 btrfs_tree_unlock(cow);
649 free_extent_buffer(cow);
650 btrfs_abort_transaction(trans, ret);
651 return ret;
652 }
653 }
654 btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
655 parent_start, last_ref);
656 }
657 if (unlock_orig)
658 btrfs_tree_unlock(buf);
659 free_extent_buffer_stale(buf);
660 btrfs_mark_buffer_dirty(trans, cow);
661 *cow_ret = cow;
662 return 0;
663}
664
665static inline int should_cow_block(struct btrfs_trans_handle *trans,
666 struct btrfs_root *root,
667 struct extent_buffer *buf)
668{
669 if (btrfs_is_testing(root->fs_info))
670 return 0;
671
672 /* Ensure we can see the FORCE_COW bit */
673 smp_mb__before_atomic();
674
675 /*
676 * We do not need to cow a block if
677 * 1) this block is not created or changed in this transaction;
678 * 2) this block does not belong to TREE_RELOC tree;
679 * 3) the root is not forced COW.
680 *
681 * What is forced COW:
682 * when we create snapshot during committing the transaction,
683 * after we've finished copying src root, we must COW the shared
684 * block to ensure the metadata consistency.
685 */
686 if (btrfs_header_generation(buf) == trans->transid &&
687 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
688 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
689 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
690 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
691 return 0;
692 return 1;
693}
694
695/*
696 * COWs a single block, see btrfs_force_cow_block() for the real work.
697 * This version of it has extra checks so that a block isn't COWed more than
698 * once per transaction, as long as it hasn't been written yet
699 */
700int btrfs_cow_block(struct btrfs_trans_handle *trans,
701 struct btrfs_root *root, struct extent_buffer *buf,
702 struct extent_buffer *parent, int parent_slot,
703 struct extent_buffer **cow_ret,
704 enum btrfs_lock_nesting nest)
705{
706 struct btrfs_fs_info *fs_info = root->fs_info;
707 u64 search_start;
708 int ret;
709
710 if (unlikely(test_bit(BTRFS_ROOT_DELETING, &root->state))) {
711 btrfs_abort_transaction(trans, -EUCLEAN);
712 btrfs_crit(fs_info,
713 "attempt to COW block %llu on root %llu that is being deleted",
714 buf->start, btrfs_root_id(root));
715 return -EUCLEAN;
716 }
717
718 /*
719 * COWing must happen through a running transaction, which always
720 * matches the current fs generation (it's a transaction with a state
721 * less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs
722 * into error state to prevent the commit of any transaction.
723 */
724 if (unlikely(trans->transaction != fs_info->running_transaction ||
725 trans->transid != fs_info->generation)) {
726 btrfs_abort_transaction(trans, -EUCLEAN);
727 btrfs_crit(fs_info,
728"unexpected transaction when attempting to COW block %llu on root %llu, transaction %llu running transaction %llu fs generation %llu",
729 buf->start, btrfs_root_id(root), trans->transid,
730 fs_info->running_transaction->transid,
731 fs_info->generation);
732 return -EUCLEAN;
733 }
734
735 if (!should_cow_block(trans, root, buf)) {
736 *cow_ret = buf;
737 return 0;
738 }
739
740 search_start = round_down(buf->start, SZ_1G);
741
742 /*
743 * Before CoWing this block for later modification, check if it's
744 * the subtree root and do the delayed subtree trace if needed.
745 *
746 * Also We don't care about the error, as it's handled internally.
747 */
748 btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
749 ret = btrfs_force_cow_block(trans, root, buf, parent, parent_slot,
750 cow_ret, search_start, 0, nest);
751
752 trace_btrfs_cow_block(root, buf, *cow_ret);
753
754 return ret;
755}
756ALLOW_ERROR_INJECTION(btrfs_cow_block, ERRNO);
757
758/*
759 * same as comp_keys only with two btrfs_key's
760 */
761int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
762{
763 if (k1->objectid > k2->objectid)
764 return 1;
765 if (k1->objectid < k2->objectid)
766 return -1;
767 if (k1->type > k2->type)
768 return 1;
769 if (k1->type < k2->type)
770 return -1;
771 if (k1->offset > k2->offset)
772 return 1;
773 if (k1->offset < k2->offset)
774 return -1;
775 return 0;
776}
777
778/*
779 * Search for a key in the given extent_buffer.
780 *
781 * The lower boundary for the search is specified by the slot number @first_slot.
782 * Use a value of 0 to search over the whole extent buffer. Works for both
783 * leaves and nodes.
784 *
785 * The slot in the extent buffer is returned via @slot. If the key exists in the
786 * extent buffer, then @slot will point to the slot where the key is, otherwise
787 * it points to the slot where you would insert the key.
788 *
789 * Slot may point to the total number of items (i.e. one position beyond the last
790 * key) if the key is bigger than the last key in the extent buffer.
791 */
792int btrfs_bin_search(struct extent_buffer *eb, int first_slot,
793 const struct btrfs_key *key, int *slot)
794{
795 unsigned long p;
796 int item_size;
797 /*
798 * Use unsigned types for the low and high slots, so that we get a more
799 * efficient division in the search loop below.
800 */
801 u32 low = first_slot;
802 u32 high = btrfs_header_nritems(eb);
803 int ret;
804 const int key_size = sizeof(struct btrfs_disk_key);
805
806 if (unlikely(low > high)) {
807 btrfs_err(eb->fs_info,
808 "%s: low (%u) > high (%u) eb %llu owner %llu level %d",
809 __func__, low, high, eb->start,
810 btrfs_header_owner(eb), btrfs_header_level(eb));
811 return -EINVAL;
812 }
813
814 if (btrfs_header_level(eb) == 0) {
815 p = offsetof(struct btrfs_leaf, items);
816 item_size = sizeof(struct btrfs_item);
817 } else {
818 p = offsetof(struct btrfs_node, ptrs);
819 item_size = sizeof(struct btrfs_key_ptr);
820 }
821
822 while (low < high) {
823 const int unit_size = folio_size(eb->folios[0]);
824 unsigned long oil;
825 unsigned long offset;
826 struct btrfs_disk_key *tmp;
827 struct btrfs_disk_key unaligned;
828 int mid;
829
830 mid = (low + high) / 2;
831 offset = p + mid * item_size;
832 oil = get_eb_offset_in_folio(eb, offset);
833
834 if (oil + key_size <= unit_size) {
835 const unsigned long idx = get_eb_folio_index(eb, offset);
836 char *kaddr = folio_address(eb->folios[idx]);
837
838 oil = get_eb_offset_in_folio(eb, offset);
839 tmp = (struct btrfs_disk_key *)(kaddr + oil);
840 } else {
841 read_extent_buffer(eb, &unaligned, offset, key_size);
842 tmp = &unaligned;
843 }
844
845 ret = btrfs_comp_keys(tmp, key);
846
847 if (ret < 0)
848 low = mid + 1;
849 else if (ret > 0)
850 high = mid;
851 else {
852 *slot = mid;
853 return 0;
854 }
855 }
856 *slot = low;
857 return 1;
858}
859
860static void root_add_used_bytes(struct btrfs_root *root)
861{
862 spin_lock(&root->accounting_lock);
863 btrfs_set_root_used(&root->root_item,
864 btrfs_root_used(&root->root_item) + root->fs_info->nodesize);
865 spin_unlock(&root->accounting_lock);
866}
867
868static void root_sub_used_bytes(struct btrfs_root *root)
869{
870 spin_lock(&root->accounting_lock);
871 btrfs_set_root_used(&root->root_item,
872 btrfs_root_used(&root->root_item) - root->fs_info->nodesize);
873 spin_unlock(&root->accounting_lock);
874}
875
876/* given a node and slot number, this reads the blocks it points to. The
877 * extent buffer is returned with a reference taken (but unlocked).
878 */
879struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
880 int slot)
881{
882 int level = btrfs_header_level(parent);
883 struct btrfs_tree_parent_check check = { 0 };
884 struct extent_buffer *eb;
885
886 if (slot < 0 || slot >= btrfs_header_nritems(parent))
887 return ERR_PTR(-ENOENT);
888
889 ASSERT(level);
890
891 check.level = level - 1;
892 check.transid = btrfs_node_ptr_generation(parent, slot);
893 check.owner_root = btrfs_header_owner(parent);
894 check.has_first_key = true;
895 btrfs_node_key_to_cpu(parent, &check.first_key, slot);
896
897 eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
898 &check);
899 if (IS_ERR(eb))
900 return eb;
901 if (!extent_buffer_uptodate(eb)) {
902 free_extent_buffer(eb);
903 return ERR_PTR(-EIO);
904 }
905
906 return eb;
907}
908
909/*
910 * node level balancing, used to make sure nodes are in proper order for
911 * item deletion. We balance from the top down, so we have to make sure
912 * that a deletion won't leave an node completely empty later on.
913 */
914static noinline int balance_level(struct btrfs_trans_handle *trans,
915 struct btrfs_root *root,
916 struct btrfs_path *path, int level)
917{
918 struct btrfs_fs_info *fs_info = root->fs_info;
919 struct extent_buffer *right = NULL;
920 struct extent_buffer *mid;
921 struct extent_buffer *left = NULL;
922 struct extent_buffer *parent = NULL;
923 int ret = 0;
924 int wret;
925 int pslot;
926 int orig_slot = path->slots[level];
927 u64 orig_ptr;
928
929 ASSERT(level > 0);
930
931 mid = path->nodes[level];
932
933 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK);
934 WARN_ON(btrfs_header_generation(mid) != trans->transid);
935
936 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
937
938 if (level < BTRFS_MAX_LEVEL - 1) {
939 parent = path->nodes[level + 1];
940 pslot = path->slots[level + 1];
941 }
942
943 /*
944 * deal with the case where there is only one pointer in the root
945 * by promoting the node below to a root
946 */
947 if (!parent) {
948 struct extent_buffer *child;
949
950 if (btrfs_header_nritems(mid) != 1)
951 return 0;
952
953 /* promote the child to a root */
954 child = btrfs_read_node_slot(mid, 0);
955 if (IS_ERR(child)) {
956 ret = PTR_ERR(child);
957 goto out;
958 }
959
960 btrfs_tree_lock(child);
961 ret = btrfs_cow_block(trans, root, child, mid, 0, &child,
962 BTRFS_NESTING_COW);
963 if (ret) {
964 btrfs_tree_unlock(child);
965 free_extent_buffer(child);
966 goto out;
967 }
968
969 ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
970 if (ret < 0) {
971 btrfs_tree_unlock(child);
972 free_extent_buffer(child);
973 btrfs_abort_transaction(trans, ret);
974 goto out;
975 }
976 rcu_assign_pointer(root->node, child);
977
978 add_root_to_dirty_list(root);
979 btrfs_tree_unlock(child);
980
981 path->locks[level] = 0;
982 path->nodes[level] = NULL;
983 btrfs_clear_buffer_dirty(trans, mid);
984 btrfs_tree_unlock(mid);
985 /* once for the path */
986 free_extent_buffer(mid);
987
988 root_sub_used_bytes(root);
989 btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
990 /* once for the root ptr */
991 free_extent_buffer_stale(mid);
992 return 0;
993 }
994 if (btrfs_header_nritems(mid) >
995 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
996 return 0;
997
998 if (pslot) {
999 left = btrfs_read_node_slot(parent, pslot - 1);
1000 if (IS_ERR(left)) {
1001 ret = PTR_ERR(left);
1002 left = NULL;
1003 goto out;
1004 }
1005
1006 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
1007 wret = btrfs_cow_block(trans, root, left,
1008 parent, pslot - 1, &left,
1009 BTRFS_NESTING_LEFT_COW);
1010 if (wret) {
1011 ret = wret;
1012 goto out;
1013 }
1014 }
1015
1016 if (pslot + 1 < btrfs_header_nritems(parent)) {
1017 right = btrfs_read_node_slot(parent, pslot + 1);
1018 if (IS_ERR(right)) {
1019 ret = PTR_ERR(right);
1020 right = NULL;
1021 goto out;
1022 }
1023
1024 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
1025 wret = btrfs_cow_block(trans, root, right,
1026 parent, pslot + 1, &right,
1027 BTRFS_NESTING_RIGHT_COW);
1028 if (wret) {
1029 ret = wret;
1030 goto out;
1031 }
1032 }
1033
1034 /* first, try to make some room in the middle buffer */
1035 if (left) {
1036 orig_slot += btrfs_header_nritems(left);
1037 wret = push_node_left(trans, left, mid, 1);
1038 if (wret < 0)
1039 ret = wret;
1040 }
1041
1042 /*
1043 * then try to empty the right most buffer into the middle
1044 */
1045 if (right) {
1046 wret = push_node_left(trans, mid, right, 1);
1047 if (wret < 0 && wret != -ENOSPC)
1048 ret = wret;
1049 if (btrfs_header_nritems(right) == 0) {
1050 btrfs_clear_buffer_dirty(trans, right);
1051 btrfs_tree_unlock(right);
1052 ret = btrfs_del_ptr(trans, root, path, level + 1, pslot + 1);
1053 if (ret < 0) {
1054 free_extent_buffer_stale(right);
1055 right = NULL;
1056 goto out;
1057 }
1058 root_sub_used_bytes(root);
1059 btrfs_free_tree_block(trans, btrfs_root_id(root), right,
1060 0, 1);
1061 free_extent_buffer_stale(right);
1062 right = NULL;
1063 } else {
1064 struct btrfs_disk_key right_key;
1065 btrfs_node_key(right, &right_key, 0);
1066 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1067 BTRFS_MOD_LOG_KEY_REPLACE);
1068 if (ret < 0) {
1069 btrfs_abort_transaction(trans, ret);
1070 goto out;
1071 }
1072 btrfs_set_node_key(parent, &right_key, pslot + 1);
1073 btrfs_mark_buffer_dirty(trans, parent);
1074 }
1075 }
1076 if (btrfs_header_nritems(mid) == 1) {
1077 /*
1078 * we're not allowed to leave a node with one item in the
1079 * tree during a delete. A deletion from lower in the tree
1080 * could try to delete the only pointer in this node.
1081 * So, pull some keys from the left.
1082 * There has to be a left pointer at this point because
1083 * otherwise we would have pulled some pointers from the
1084 * right
1085 */
1086 if (unlikely(!left)) {
1087 btrfs_crit(fs_info,
1088"missing left child when middle child only has 1 item, parent bytenr %llu level %d mid bytenr %llu root %llu",
1089 parent->start, btrfs_header_level(parent),
1090 mid->start, btrfs_root_id(root));
1091 ret = -EUCLEAN;
1092 btrfs_abort_transaction(trans, ret);
1093 goto out;
1094 }
1095 wret = balance_node_right(trans, mid, left);
1096 if (wret < 0) {
1097 ret = wret;
1098 goto out;
1099 }
1100 if (wret == 1) {
1101 wret = push_node_left(trans, left, mid, 1);
1102 if (wret < 0)
1103 ret = wret;
1104 }
1105 BUG_ON(wret == 1);
1106 }
1107 if (btrfs_header_nritems(mid) == 0) {
1108 btrfs_clear_buffer_dirty(trans, mid);
1109 btrfs_tree_unlock(mid);
1110 ret = btrfs_del_ptr(trans, root, path, level + 1, pslot);
1111 if (ret < 0) {
1112 free_extent_buffer_stale(mid);
1113 mid = NULL;
1114 goto out;
1115 }
1116 root_sub_used_bytes(root);
1117 btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
1118 free_extent_buffer_stale(mid);
1119 mid = NULL;
1120 } else {
1121 /* update the parent key to reflect our changes */
1122 struct btrfs_disk_key mid_key;
1123 btrfs_node_key(mid, &mid_key, 0);
1124 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1125 BTRFS_MOD_LOG_KEY_REPLACE);
1126 if (ret < 0) {
1127 btrfs_abort_transaction(trans, ret);
1128 goto out;
1129 }
1130 btrfs_set_node_key(parent, &mid_key, pslot);
1131 btrfs_mark_buffer_dirty(trans, parent);
1132 }
1133
1134 /* update the path */
1135 if (left) {
1136 if (btrfs_header_nritems(left) > orig_slot) {
1137 atomic_inc(&left->refs);
1138 /* left was locked after cow */
1139 path->nodes[level] = left;
1140 path->slots[level + 1] -= 1;
1141 path->slots[level] = orig_slot;
1142 if (mid) {
1143 btrfs_tree_unlock(mid);
1144 free_extent_buffer(mid);
1145 }
1146 } else {
1147 orig_slot -= btrfs_header_nritems(left);
1148 path->slots[level] = orig_slot;
1149 }
1150 }
1151 /* double check we haven't messed things up */
1152 if (orig_ptr !=
1153 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1154 BUG();
1155out:
1156 if (right) {
1157 btrfs_tree_unlock(right);
1158 free_extent_buffer(right);
1159 }
1160 if (left) {
1161 if (path->nodes[level] != left)
1162 btrfs_tree_unlock(left);
1163 free_extent_buffer(left);
1164 }
1165 return ret;
1166}
1167
1168/* Node balancing for insertion. Here we only split or push nodes around
1169 * when they are completely full. This is also done top down, so we
1170 * have to be pessimistic.
1171 */
1172static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1173 struct btrfs_root *root,
1174 struct btrfs_path *path, int level)
1175{
1176 struct btrfs_fs_info *fs_info = root->fs_info;
1177 struct extent_buffer *right = NULL;
1178 struct extent_buffer *mid;
1179 struct extent_buffer *left = NULL;
1180 struct extent_buffer *parent = NULL;
1181 int ret = 0;
1182 int wret;
1183 int pslot;
1184 int orig_slot = path->slots[level];
1185
1186 if (level == 0)
1187 return 1;
1188
1189 mid = path->nodes[level];
1190 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1191
1192 if (level < BTRFS_MAX_LEVEL - 1) {
1193 parent = path->nodes[level + 1];
1194 pslot = path->slots[level + 1];
1195 }
1196
1197 if (!parent)
1198 return 1;
1199
1200 /* first, try to make some room in the middle buffer */
1201 if (pslot) {
1202 u32 left_nr;
1203
1204 left = btrfs_read_node_slot(parent, pslot - 1);
1205 if (IS_ERR(left))
1206 return PTR_ERR(left);
1207
1208 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
1209
1210 left_nr = btrfs_header_nritems(left);
1211 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1212 wret = 1;
1213 } else {
1214 ret = btrfs_cow_block(trans, root, left, parent,
1215 pslot - 1, &left,
1216 BTRFS_NESTING_LEFT_COW);
1217 if (ret)
1218 wret = 1;
1219 else {
1220 wret = push_node_left(trans, left, mid, 0);
1221 }
1222 }
1223 if (wret < 0)
1224 ret = wret;
1225 if (wret == 0) {
1226 struct btrfs_disk_key disk_key;
1227 orig_slot += left_nr;
1228 btrfs_node_key(mid, &disk_key, 0);
1229 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1230 BTRFS_MOD_LOG_KEY_REPLACE);
1231 if (ret < 0) {
1232 btrfs_tree_unlock(left);
1233 free_extent_buffer(left);
1234 btrfs_abort_transaction(trans, ret);
1235 return ret;
1236 }
1237 btrfs_set_node_key(parent, &disk_key, pslot);
1238 btrfs_mark_buffer_dirty(trans, parent);
1239 if (btrfs_header_nritems(left) > orig_slot) {
1240 path->nodes[level] = left;
1241 path->slots[level + 1] -= 1;
1242 path->slots[level] = orig_slot;
1243 btrfs_tree_unlock(mid);
1244 free_extent_buffer(mid);
1245 } else {
1246 orig_slot -=
1247 btrfs_header_nritems(left);
1248 path->slots[level] = orig_slot;
1249 btrfs_tree_unlock(left);
1250 free_extent_buffer(left);
1251 }
1252 return 0;
1253 }
1254 btrfs_tree_unlock(left);
1255 free_extent_buffer(left);
1256 }
1257
1258 /*
1259 * then try to empty the right most buffer into the middle
1260 */
1261 if (pslot + 1 < btrfs_header_nritems(parent)) {
1262 u32 right_nr;
1263
1264 right = btrfs_read_node_slot(parent, pslot + 1);
1265 if (IS_ERR(right))
1266 return PTR_ERR(right);
1267
1268 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
1269
1270 right_nr = btrfs_header_nritems(right);
1271 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1272 wret = 1;
1273 } else {
1274 ret = btrfs_cow_block(trans, root, right,
1275 parent, pslot + 1,
1276 &right, BTRFS_NESTING_RIGHT_COW);
1277 if (ret)
1278 wret = 1;
1279 else {
1280 wret = balance_node_right(trans, right, mid);
1281 }
1282 }
1283 if (wret < 0)
1284 ret = wret;
1285 if (wret == 0) {
1286 struct btrfs_disk_key disk_key;
1287
1288 btrfs_node_key(right, &disk_key, 0);
1289 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1290 BTRFS_MOD_LOG_KEY_REPLACE);
1291 if (ret < 0) {
1292 btrfs_tree_unlock(right);
1293 free_extent_buffer(right);
1294 btrfs_abort_transaction(trans, ret);
1295 return ret;
1296 }
1297 btrfs_set_node_key(parent, &disk_key, pslot + 1);
1298 btrfs_mark_buffer_dirty(trans, parent);
1299
1300 if (btrfs_header_nritems(mid) <= orig_slot) {
1301 path->nodes[level] = right;
1302 path->slots[level + 1] += 1;
1303 path->slots[level] = orig_slot -
1304 btrfs_header_nritems(mid);
1305 btrfs_tree_unlock(mid);
1306 free_extent_buffer(mid);
1307 } else {
1308 btrfs_tree_unlock(right);
1309 free_extent_buffer(right);
1310 }
1311 return 0;
1312 }
1313 btrfs_tree_unlock(right);
1314 free_extent_buffer(right);
1315 }
1316 return 1;
1317}
1318
1319/*
1320 * readahead one full node of leaves, finding things that are close
1321 * to the block in 'slot', and triggering ra on them.
1322 */
1323static void reada_for_search(struct btrfs_fs_info *fs_info,
1324 struct btrfs_path *path,
1325 int level, int slot, u64 objectid)
1326{
1327 struct extent_buffer *node;
1328 struct btrfs_disk_key disk_key;
1329 u32 nritems;
1330 u64 search;
1331 u64 target;
1332 u64 nread = 0;
1333 u64 nread_max;
1334 u32 nr;
1335 u32 blocksize;
1336 u32 nscan = 0;
1337
1338 if (level != 1 && path->reada != READA_FORWARD_ALWAYS)
1339 return;
1340
1341 if (!path->nodes[level])
1342 return;
1343
1344 node = path->nodes[level];
1345
1346 /*
1347 * Since the time between visiting leaves is much shorter than the time
1348 * between visiting nodes, limit read ahead of nodes to 1, to avoid too
1349 * much IO at once (possibly random).
1350 */
1351 if (path->reada == READA_FORWARD_ALWAYS) {
1352 if (level > 1)
1353 nread_max = node->fs_info->nodesize;
1354 else
1355 nread_max = SZ_128K;
1356 } else {
1357 nread_max = SZ_64K;
1358 }
1359
1360 search = btrfs_node_blockptr(node, slot);
1361 blocksize = fs_info->nodesize;
1362 if (path->reada != READA_FORWARD_ALWAYS) {
1363 struct extent_buffer *eb;
1364
1365 eb = find_extent_buffer(fs_info, search);
1366 if (eb) {
1367 free_extent_buffer(eb);
1368 return;
1369 }
1370 }
1371
1372 target = search;
1373
1374 nritems = btrfs_header_nritems(node);
1375 nr = slot;
1376
1377 while (1) {
1378 if (path->reada == READA_BACK) {
1379 if (nr == 0)
1380 break;
1381 nr--;
1382 } else if (path->reada == READA_FORWARD ||
1383 path->reada == READA_FORWARD_ALWAYS) {
1384 nr++;
1385 if (nr >= nritems)
1386 break;
1387 }
1388 if (path->reada == READA_BACK && objectid) {
1389 btrfs_node_key(node, &disk_key, nr);
1390 if (btrfs_disk_key_objectid(&disk_key) != objectid)
1391 break;
1392 }
1393 search = btrfs_node_blockptr(node, nr);
1394 if (path->reada == READA_FORWARD_ALWAYS ||
1395 (search <= target && target - search <= 65536) ||
1396 (search > target && search - target <= 65536)) {
1397 btrfs_readahead_node_child(node, nr);
1398 nread += blocksize;
1399 }
1400 nscan++;
1401 if (nread > nread_max || nscan > 32)
1402 break;
1403 }
1404}
1405
1406static noinline void reada_for_balance(struct btrfs_path *path, int level)
1407{
1408 struct extent_buffer *parent;
1409 int slot;
1410 int nritems;
1411
1412 parent = path->nodes[level + 1];
1413 if (!parent)
1414 return;
1415
1416 nritems = btrfs_header_nritems(parent);
1417 slot = path->slots[level + 1];
1418
1419 if (slot > 0)
1420 btrfs_readahead_node_child(parent, slot - 1);
1421 if (slot + 1 < nritems)
1422 btrfs_readahead_node_child(parent, slot + 1);
1423}
1424
1425
1426/*
1427 * when we walk down the tree, it is usually safe to unlock the higher layers
1428 * in the tree. The exceptions are when our path goes through slot 0, because
1429 * operations on the tree might require changing key pointers higher up in the
1430 * tree.
1431 *
1432 * callers might also have set path->keep_locks, which tells this code to keep
1433 * the lock if the path points to the last slot in the block. This is part of
1434 * walking through the tree, and selecting the next slot in the higher block.
1435 *
1436 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
1437 * if lowest_unlock is 1, level 0 won't be unlocked
1438 */
1439static noinline void unlock_up(struct btrfs_path *path, int level,
1440 int lowest_unlock, int min_write_lock_level,
1441 int *write_lock_level)
1442{
1443 int i;
1444 int skip_level = level;
1445 bool check_skip = true;
1446
1447 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1448 if (!path->nodes[i])
1449 break;
1450 if (!path->locks[i])
1451 break;
1452
1453 if (check_skip) {
1454 if (path->slots[i] == 0) {
1455 skip_level = i + 1;
1456 continue;
1457 }
1458
1459 if (path->keep_locks) {
1460 u32 nritems;
1461
1462 nritems = btrfs_header_nritems(path->nodes[i]);
1463 if (nritems < 1 || path->slots[i] >= nritems - 1) {
1464 skip_level = i + 1;
1465 continue;
1466 }
1467 }
1468 }
1469
1470 if (i >= lowest_unlock && i > skip_level) {
1471 check_skip = false;
1472 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
1473 path->locks[i] = 0;
1474 if (write_lock_level &&
1475 i > min_write_lock_level &&
1476 i <= *write_lock_level) {
1477 *write_lock_level = i - 1;
1478 }
1479 }
1480 }
1481}
1482
1483/*
1484 * Helper function for btrfs_search_slot() and other functions that do a search
1485 * on a btree. The goal is to find a tree block in the cache (the radix tree at
1486 * fs_info->buffer_radix), but if we can't find it, or it's not up to date, read
1487 * its pages from disk.
1488 *
1489 * Returns -EAGAIN, with the path unlocked, if the caller needs to repeat the
1490 * whole btree search, starting again from the current root node.
1491 */
1492static int
1493read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
1494 struct extent_buffer **eb_ret, int level, int slot,
1495 const struct btrfs_key *key)
1496{
1497 struct btrfs_fs_info *fs_info = root->fs_info;
1498 struct btrfs_tree_parent_check check = { 0 };
1499 u64 blocknr;
1500 u64 gen;
1501 struct extent_buffer *tmp;
1502 int ret;
1503 int parent_level;
1504 bool unlock_up;
1505
1506 unlock_up = ((level + 1 < BTRFS_MAX_LEVEL) && p->locks[level + 1]);
1507 blocknr = btrfs_node_blockptr(*eb_ret, slot);
1508 gen = btrfs_node_ptr_generation(*eb_ret, slot);
1509 parent_level = btrfs_header_level(*eb_ret);
1510 btrfs_node_key_to_cpu(*eb_ret, &check.first_key, slot);
1511 check.has_first_key = true;
1512 check.level = parent_level - 1;
1513 check.transid = gen;
1514 check.owner_root = root->root_key.objectid;
1515
1516 /*
1517 * If we need to read an extent buffer from disk and we are holding locks
1518 * on upper level nodes, we unlock all the upper nodes before reading the
1519 * extent buffer, and then return -EAGAIN to the caller as it needs to
1520 * restart the search. We don't release the lock on the current level
1521 * because we need to walk this node to figure out which blocks to read.
1522 */
1523 tmp = find_extent_buffer(fs_info, blocknr);
1524 if (tmp) {
1525 if (p->reada == READA_FORWARD_ALWAYS)
1526 reada_for_search(fs_info, p, level, slot, key->objectid);
1527
1528 /* first we do an atomic uptodate check */
1529 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
1530 /*
1531 * Do extra check for first_key, eb can be stale due to
1532 * being cached, read from scrub, or have multiple
1533 * parents (shared tree blocks).
1534 */
1535 if (btrfs_verify_level_key(tmp,
1536 parent_level - 1, &check.first_key, gen)) {
1537 free_extent_buffer(tmp);
1538 return -EUCLEAN;
1539 }
1540 *eb_ret = tmp;
1541 return 0;
1542 }
1543
1544 if (p->nowait) {
1545 free_extent_buffer(tmp);
1546 return -EAGAIN;
1547 }
1548
1549 if (unlock_up)
1550 btrfs_unlock_up_safe(p, level + 1);
1551
1552 /* now we're allowed to do a blocking uptodate check */
1553 ret = btrfs_read_extent_buffer(tmp, &check);
1554 if (ret) {
1555 free_extent_buffer(tmp);
1556 btrfs_release_path(p);
1557 return -EIO;
1558 }
1559 if (btrfs_check_eb_owner(tmp, root->root_key.objectid)) {
1560 free_extent_buffer(tmp);
1561 btrfs_release_path(p);
1562 return -EUCLEAN;
1563 }
1564
1565 if (unlock_up)
1566 ret = -EAGAIN;
1567
1568 goto out;
1569 } else if (p->nowait) {
1570 return -EAGAIN;
1571 }
1572
1573 if (unlock_up) {
1574 btrfs_unlock_up_safe(p, level + 1);
1575 ret = -EAGAIN;
1576 } else {
1577 ret = 0;
1578 }
1579
1580 if (p->reada != READA_NONE)
1581 reada_for_search(fs_info, p, level, slot, key->objectid);
1582
1583 tmp = read_tree_block(fs_info, blocknr, &check);
1584 if (IS_ERR(tmp)) {
1585 btrfs_release_path(p);
1586 return PTR_ERR(tmp);
1587 }
1588 /*
1589 * If the read above didn't mark this buffer up to date,
1590 * it will never end up being up to date. Set ret to EIO now
1591 * and give up so that our caller doesn't loop forever
1592 * on our EAGAINs.
1593 */
1594 if (!extent_buffer_uptodate(tmp))
1595 ret = -EIO;
1596
1597out:
1598 if (ret == 0) {
1599 *eb_ret = tmp;
1600 } else {
1601 free_extent_buffer(tmp);
1602 btrfs_release_path(p);
1603 }
1604
1605 return ret;
1606}
1607
1608/*
1609 * helper function for btrfs_search_slot. This does all of the checks
1610 * for node-level blocks and does any balancing required based on
1611 * the ins_len.
1612 *
1613 * If no extra work was required, zero is returned. If we had to
1614 * drop the path, -EAGAIN is returned and btrfs_search_slot must
1615 * start over
1616 */
1617static int
1618setup_nodes_for_search(struct btrfs_trans_handle *trans,
1619 struct btrfs_root *root, struct btrfs_path *p,
1620 struct extent_buffer *b, int level, int ins_len,
1621 int *write_lock_level)
1622{
1623 struct btrfs_fs_info *fs_info = root->fs_info;
1624 int ret = 0;
1625
1626 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
1627 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
1628
1629 if (*write_lock_level < level + 1) {
1630 *write_lock_level = level + 1;
1631 btrfs_release_path(p);
1632 return -EAGAIN;
1633 }
1634
1635 reada_for_balance(p, level);
1636 ret = split_node(trans, root, p, level);
1637
1638 b = p->nodes[level];
1639 } else if (ins_len < 0 && btrfs_header_nritems(b) <
1640 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
1641
1642 if (*write_lock_level < level + 1) {
1643 *write_lock_level = level + 1;
1644 btrfs_release_path(p);
1645 return -EAGAIN;
1646 }
1647
1648 reada_for_balance(p, level);
1649 ret = balance_level(trans, root, p, level);
1650 if (ret)
1651 return ret;
1652
1653 b = p->nodes[level];
1654 if (!b) {
1655 btrfs_release_path(p);
1656 return -EAGAIN;
1657 }
1658 BUG_ON(btrfs_header_nritems(b) == 1);
1659 }
1660 return ret;
1661}
1662
1663int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
1664 u64 iobjectid, u64 ioff, u8 key_type,
1665 struct btrfs_key *found_key)
1666{
1667 int ret;
1668 struct btrfs_key key;
1669 struct extent_buffer *eb;
1670
1671 ASSERT(path);
1672 ASSERT(found_key);
1673
1674 key.type = key_type;
1675 key.objectid = iobjectid;
1676 key.offset = ioff;
1677
1678 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1679 if (ret < 0)
1680 return ret;
1681
1682 eb = path->nodes[0];
1683 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1684 ret = btrfs_next_leaf(fs_root, path);
1685 if (ret)
1686 return ret;
1687 eb = path->nodes[0];
1688 }
1689
1690 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1691 if (found_key->type != key.type ||
1692 found_key->objectid != key.objectid)
1693 return 1;
1694
1695 return 0;
1696}
1697
1698static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
1699 struct btrfs_path *p,
1700 int write_lock_level)
1701{
1702 struct extent_buffer *b;
1703 int root_lock = 0;
1704 int level = 0;
1705
1706 if (p->search_commit_root) {
1707 b = root->commit_root;
1708 atomic_inc(&b->refs);
1709 level = btrfs_header_level(b);
1710 /*
1711 * Ensure that all callers have set skip_locking when
1712 * p->search_commit_root = 1.
1713 */
1714 ASSERT(p->skip_locking == 1);
1715
1716 goto out;
1717 }
1718
1719 if (p->skip_locking) {
1720 b = btrfs_root_node(root);
1721 level = btrfs_header_level(b);
1722 goto out;
1723 }
1724
1725 /* We try very hard to do read locks on the root */
1726 root_lock = BTRFS_READ_LOCK;
1727
1728 /*
1729 * If the level is set to maximum, we can skip trying to get the read
1730 * lock.
1731 */
1732 if (write_lock_level < BTRFS_MAX_LEVEL) {
1733 /*
1734 * We don't know the level of the root node until we actually
1735 * have it read locked
1736 */
1737 if (p->nowait) {
1738 b = btrfs_try_read_lock_root_node(root);
1739 if (IS_ERR(b))
1740 return b;
1741 } else {
1742 b = btrfs_read_lock_root_node(root);
1743 }
1744 level = btrfs_header_level(b);
1745 if (level > write_lock_level)
1746 goto out;
1747
1748 /* Whoops, must trade for write lock */
1749 btrfs_tree_read_unlock(b);
1750 free_extent_buffer(b);
1751 }
1752
1753 b = btrfs_lock_root_node(root);
1754 root_lock = BTRFS_WRITE_LOCK;
1755
1756 /* The level might have changed, check again */
1757 level = btrfs_header_level(b);
1758
1759out:
1760 /*
1761 * The root may have failed to write out at some point, and thus is no
1762 * longer valid, return an error in this case.
1763 */
1764 if (!extent_buffer_uptodate(b)) {
1765 if (root_lock)
1766 btrfs_tree_unlock_rw(b, root_lock);
1767 free_extent_buffer(b);
1768 return ERR_PTR(-EIO);
1769 }
1770
1771 p->nodes[level] = b;
1772 if (!p->skip_locking)
1773 p->locks[level] = root_lock;
1774 /*
1775 * Callers are responsible for dropping b's references.
1776 */
1777 return b;
1778}
1779
1780/*
1781 * Replace the extent buffer at the lowest level of the path with a cloned
1782 * version. The purpose is to be able to use it safely, after releasing the
1783 * commit root semaphore, even if relocation is happening in parallel, the
1784 * transaction used for relocation is committed and the extent buffer is
1785 * reallocated in the next transaction.
1786 *
1787 * This is used in a context where the caller does not prevent transaction
1788 * commits from happening, either by holding a transaction handle or holding
1789 * some lock, while it's doing searches through a commit root.
1790 * At the moment it's only used for send operations.
1791 */
1792static int finish_need_commit_sem_search(struct btrfs_path *path)
1793{
1794 const int i = path->lowest_level;
1795 const int slot = path->slots[i];
1796 struct extent_buffer *lowest = path->nodes[i];
1797 struct extent_buffer *clone;
1798
1799 ASSERT(path->need_commit_sem);
1800
1801 if (!lowest)
1802 return 0;
1803
1804 lockdep_assert_held_read(&lowest->fs_info->commit_root_sem);
1805
1806 clone = btrfs_clone_extent_buffer(lowest);
1807 if (!clone)
1808 return -ENOMEM;
1809
1810 btrfs_release_path(path);
1811 path->nodes[i] = clone;
1812 path->slots[i] = slot;
1813
1814 return 0;
1815}
1816
1817static inline int search_for_key_slot(struct extent_buffer *eb,
1818 int search_low_slot,
1819 const struct btrfs_key *key,
1820 int prev_cmp,
1821 int *slot)
1822{
1823 /*
1824 * If a previous call to btrfs_bin_search() on a parent node returned an
1825 * exact match (prev_cmp == 0), we can safely assume the target key will
1826 * always be at slot 0 on lower levels, since each key pointer
1827 * (struct btrfs_key_ptr) refers to the lowest key accessible from the
1828 * subtree it points to. Thus we can skip searching lower levels.
1829 */
1830 if (prev_cmp == 0) {
1831 *slot = 0;
1832 return 0;
1833 }
1834
1835 return btrfs_bin_search(eb, search_low_slot, key, slot);
1836}
1837
1838static int search_leaf(struct btrfs_trans_handle *trans,
1839 struct btrfs_root *root,
1840 const struct btrfs_key *key,
1841 struct btrfs_path *path,
1842 int ins_len,
1843 int prev_cmp)
1844{
1845 struct extent_buffer *leaf = path->nodes[0];
1846 int leaf_free_space = -1;
1847 int search_low_slot = 0;
1848 int ret;
1849 bool do_bin_search = true;
1850
1851 /*
1852 * If we are doing an insertion, the leaf has enough free space and the
1853 * destination slot for the key is not slot 0, then we can unlock our
1854 * write lock on the parent, and any other upper nodes, before doing the
1855 * binary search on the leaf (with search_for_key_slot()), allowing other
1856 * tasks to lock the parent and any other upper nodes.
1857 */
1858 if (ins_len > 0) {
1859 /*
1860 * Cache the leaf free space, since we will need it later and it
1861 * will not change until then.
1862 */
1863 leaf_free_space = btrfs_leaf_free_space(leaf);
1864
1865 /*
1866 * !path->locks[1] means we have a single node tree, the leaf is
1867 * the root of the tree.
1868 */
1869 if (path->locks[1] && leaf_free_space >= ins_len) {
1870 struct btrfs_disk_key first_key;
1871
1872 ASSERT(btrfs_header_nritems(leaf) > 0);
1873 btrfs_item_key(leaf, &first_key, 0);
1874
1875 /*
1876 * Doing the extra comparison with the first key is cheap,
1877 * taking into account that the first key is very likely
1878 * already in a cache line because it immediately follows
1879 * the extent buffer's header and we have recently accessed
1880 * the header's level field.
1881 */
1882 ret = btrfs_comp_keys(&first_key, key);
1883 if (ret < 0) {
1884 /*
1885 * The first key is smaller than the key we want
1886 * to insert, so we are safe to unlock all upper
1887 * nodes and we have to do the binary search.
1888 *
1889 * We do use btrfs_unlock_up_safe() and not
1890 * unlock_up() because the later does not unlock
1891 * nodes with a slot of 0 - we can safely unlock
1892 * any node even if its slot is 0 since in this
1893 * case the key does not end up at slot 0 of the
1894 * leaf and there's no need to split the leaf.
1895 */
1896 btrfs_unlock_up_safe(path, 1);
1897 search_low_slot = 1;
1898 } else {
1899 /*
1900 * The first key is >= then the key we want to
1901 * insert, so we can skip the binary search as
1902 * the target key will be at slot 0.
1903 *
1904 * We can not unlock upper nodes when the key is
1905 * less than the first key, because we will need
1906 * to update the key at slot 0 of the parent node
1907 * and possibly of other upper nodes too.
1908 * If the key matches the first key, then we can
1909 * unlock all the upper nodes, using
1910 * btrfs_unlock_up_safe() instead of unlock_up()
1911 * as stated above.
1912 */
1913 if (ret == 0)
1914 btrfs_unlock_up_safe(path, 1);
1915 /*
1916 * ret is already 0 or 1, matching the result of
1917 * a btrfs_bin_search() call, so there is no need
1918 * to adjust it.
1919 */
1920 do_bin_search = false;
1921 path->slots[0] = 0;
1922 }
1923 }
1924 }
1925
1926 if (do_bin_search) {
1927 ret = search_for_key_slot(leaf, search_low_slot, key,
1928 prev_cmp, &path->slots[0]);
1929 if (ret < 0)
1930 return ret;
1931 }
1932
1933 if (ins_len > 0) {
1934 /*
1935 * Item key already exists. In this case, if we are allowed to
1936 * insert the item (for example, in dir_item case, item key
1937 * collision is allowed), it will be merged with the original
1938 * item. Only the item size grows, no new btrfs item will be
1939 * added. If search_for_extension is not set, ins_len already
1940 * accounts the size btrfs_item, deduct it here so leaf space
1941 * check will be correct.
1942 */
1943 if (ret == 0 && !path->search_for_extension) {
1944 ASSERT(ins_len >= sizeof(struct btrfs_item));
1945 ins_len -= sizeof(struct btrfs_item);
1946 }
1947
1948 ASSERT(leaf_free_space >= 0);
1949
1950 if (leaf_free_space < ins_len) {
1951 int err;
1952
1953 err = split_leaf(trans, root, key, path, ins_len,
1954 (ret == 0));
1955 ASSERT(err <= 0);
1956 if (WARN_ON(err > 0))
1957 err = -EUCLEAN;
1958 if (err)
1959 ret = err;
1960 }
1961 }
1962
1963 return ret;
1964}
1965
1966/*
1967 * Look for a key in a tree and perform necessary modifications to preserve
1968 * tree invariants.
1969 *
1970 * @trans: Handle of transaction, used when modifying the tree
1971 * @p: Holds all btree nodes along the search path
1972 * @root: The root node of the tree
1973 * @key: The key we are looking for
1974 * @ins_len: Indicates purpose of search:
1975 * >0 for inserts it's size of item inserted (*)
1976 * <0 for deletions
1977 * 0 for plain searches, not modifying the tree
1978 *
1979 * (*) If size of item inserted doesn't include
1980 * sizeof(struct btrfs_item), then p->search_for_extension must
1981 * be set.
1982 * @cow: boolean should CoW operations be performed. Must always be 1
1983 * when modifying the tree.
1984 *
1985 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
1986 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
1987 *
1988 * If @key is found, 0 is returned and you can find the item in the leaf level
1989 * of the path (level 0)
1990 *
1991 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
1992 * points to the slot where it should be inserted
1993 *
1994 * If an error is encountered while searching the tree a negative error number
1995 * is returned
1996 */
1997int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1998 const struct btrfs_key *key, struct btrfs_path *p,
1999 int ins_len, int cow)
2000{
2001 struct btrfs_fs_info *fs_info = root->fs_info;
2002 struct extent_buffer *b;
2003 int slot;
2004 int ret;
2005 int err;
2006 int level;
2007 int lowest_unlock = 1;
2008 /* everything at write_lock_level or lower must be write locked */
2009 int write_lock_level = 0;
2010 u8 lowest_level = 0;
2011 int min_write_lock_level;
2012 int prev_cmp;
2013
2014 might_sleep();
2015
2016 lowest_level = p->lowest_level;
2017 WARN_ON(lowest_level && ins_len > 0);
2018 WARN_ON(p->nodes[0] != NULL);
2019 BUG_ON(!cow && ins_len);
2020
2021 /*
2022 * For now only allow nowait for read only operations. There's no
2023 * strict reason why we can't, we just only need it for reads so it's
2024 * only implemented for reads.
2025 */
2026 ASSERT(!p->nowait || !cow);
2027
2028 if (ins_len < 0) {
2029 lowest_unlock = 2;
2030
2031 /* when we are removing items, we might have to go up to level
2032 * two as we update tree pointers Make sure we keep write
2033 * for those levels as well
2034 */
2035 write_lock_level = 2;
2036 } else if (ins_len > 0) {
2037 /*
2038 * for inserting items, make sure we have a write lock on
2039 * level 1 so we can update keys
2040 */
2041 write_lock_level = 1;
2042 }
2043
2044 if (!cow)
2045 write_lock_level = -1;
2046
2047 if (cow && (p->keep_locks || p->lowest_level))
2048 write_lock_level = BTRFS_MAX_LEVEL;
2049
2050 min_write_lock_level = write_lock_level;
2051
2052 if (p->need_commit_sem) {
2053 ASSERT(p->search_commit_root);
2054 if (p->nowait) {
2055 if (!down_read_trylock(&fs_info->commit_root_sem))
2056 return -EAGAIN;
2057 } else {
2058 down_read(&fs_info->commit_root_sem);
2059 }
2060 }
2061
2062again:
2063 prev_cmp = -1;
2064 b = btrfs_search_slot_get_root(root, p, write_lock_level);
2065 if (IS_ERR(b)) {
2066 ret = PTR_ERR(b);
2067 goto done;
2068 }
2069
2070 while (b) {
2071 int dec = 0;
2072
2073 level = btrfs_header_level(b);
2074
2075 if (cow) {
2076 bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2077
2078 /*
2079 * if we don't really need to cow this block
2080 * then we don't want to set the path blocking,
2081 * so we test it here
2082 */
2083 if (!should_cow_block(trans, root, b))
2084 goto cow_done;
2085
2086 /*
2087 * must have write locks on this node and the
2088 * parent
2089 */
2090 if (level > write_lock_level ||
2091 (level + 1 > write_lock_level &&
2092 level + 1 < BTRFS_MAX_LEVEL &&
2093 p->nodes[level + 1])) {
2094 write_lock_level = level + 1;
2095 btrfs_release_path(p);
2096 goto again;
2097 }
2098
2099 if (last_level)
2100 err = btrfs_cow_block(trans, root, b, NULL, 0,
2101 &b,
2102 BTRFS_NESTING_COW);
2103 else
2104 err = btrfs_cow_block(trans, root, b,
2105 p->nodes[level + 1],
2106 p->slots[level + 1], &b,
2107 BTRFS_NESTING_COW);
2108 if (err) {
2109 ret = err;
2110 goto done;
2111 }
2112 }
2113cow_done:
2114 p->nodes[level] = b;
2115
2116 /*
2117 * we have a lock on b and as long as we aren't changing
2118 * the tree, there is no way to for the items in b to change.
2119 * It is safe to drop the lock on our parent before we
2120 * go through the expensive btree search on b.
2121 *
2122 * If we're inserting or deleting (ins_len != 0), then we might
2123 * be changing slot zero, which may require changing the parent.
2124 * So, we can't drop the lock until after we know which slot
2125 * we're operating on.
2126 */
2127 if (!ins_len && !p->keep_locks) {
2128 int u = level + 1;
2129
2130 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2131 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2132 p->locks[u] = 0;
2133 }
2134 }
2135
2136 if (level == 0) {
2137 if (ins_len > 0)
2138 ASSERT(write_lock_level >= 1);
2139
2140 ret = search_leaf(trans, root, key, p, ins_len, prev_cmp);
2141 if (!p->search_for_split)
2142 unlock_up(p, level, lowest_unlock,
2143 min_write_lock_level, NULL);
2144 goto done;
2145 }
2146
2147 ret = search_for_key_slot(b, 0, key, prev_cmp, &slot);
2148 if (ret < 0)
2149 goto done;
2150 prev_cmp = ret;
2151
2152 if (ret && slot > 0) {
2153 dec = 1;
2154 slot--;
2155 }
2156 p->slots[level] = slot;
2157 err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
2158 &write_lock_level);
2159 if (err == -EAGAIN)
2160 goto again;
2161 if (err) {
2162 ret = err;
2163 goto done;
2164 }
2165 b = p->nodes[level];
2166 slot = p->slots[level];
2167
2168 /*
2169 * Slot 0 is special, if we change the key we have to update
2170 * the parent pointer which means we must have a write lock on
2171 * the parent
2172 */
2173 if (slot == 0 && ins_len && write_lock_level < level + 1) {
2174 write_lock_level = level + 1;
2175 btrfs_release_path(p);
2176 goto again;
2177 }
2178
2179 unlock_up(p, level, lowest_unlock, min_write_lock_level,
2180 &write_lock_level);
2181
2182 if (level == lowest_level) {
2183 if (dec)
2184 p->slots[level]++;
2185 goto done;
2186 }
2187
2188 err = read_block_for_search(root, p, &b, level, slot, key);
2189 if (err == -EAGAIN)
2190 goto again;
2191 if (err) {
2192 ret = err;
2193 goto done;
2194 }
2195
2196 if (!p->skip_locking) {
2197 level = btrfs_header_level(b);
2198
2199 btrfs_maybe_reset_lockdep_class(root, b);
2200
2201 if (level <= write_lock_level) {
2202 btrfs_tree_lock(b);
2203 p->locks[level] = BTRFS_WRITE_LOCK;
2204 } else {
2205 if (p->nowait) {
2206 if (!btrfs_try_tree_read_lock(b)) {
2207 free_extent_buffer(b);
2208 ret = -EAGAIN;
2209 goto done;
2210 }
2211 } else {
2212 btrfs_tree_read_lock(b);
2213 }
2214 p->locks[level] = BTRFS_READ_LOCK;
2215 }
2216 p->nodes[level] = b;
2217 }
2218 }
2219 ret = 1;
2220done:
2221 if (ret < 0 && !p->skip_release_on_error)
2222 btrfs_release_path(p);
2223
2224 if (p->need_commit_sem) {
2225 int ret2;
2226
2227 ret2 = finish_need_commit_sem_search(p);
2228 up_read(&fs_info->commit_root_sem);
2229 if (ret2)
2230 ret = ret2;
2231 }
2232
2233 return ret;
2234}
2235ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO);
2236
2237/*
2238 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2239 * current state of the tree together with the operations recorded in the tree
2240 * modification log to search for the key in a previous version of this tree, as
2241 * denoted by the time_seq parameter.
2242 *
2243 * Naturally, there is no support for insert, delete or cow operations.
2244 *
2245 * The resulting path and return value will be set up as if we called
2246 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2247 */
2248int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2249 struct btrfs_path *p, u64 time_seq)
2250{
2251 struct btrfs_fs_info *fs_info = root->fs_info;
2252 struct extent_buffer *b;
2253 int slot;
2254 int ret;
2255 int err;
2256 int level;
2257 int lowest_unlock = 1;
2258 u8 lowest_level = 0;
2259
2260 lowest_level = p->lowest_level;
2261 WARN_ON(p->nodes[0] != NULL);
2262 ASSERT(!p->nowait);
2263
2264 if (p->search_commit_root) {
2265 BUG_ON(time_seq);
2266 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2267 }
2268
2269again:
2270 b = btrfs_get_old_root(root, time_seq);
2271 if (!b) {
2272 ret = -EIO;
2273 goto done;
2274 }
2275 level = btrfs_header_level(b);
2276 p->locks[level] = BTRFS_READ_LOCK;
2277
2278 while (b) {
2279 int dec = 0;
2280
2281 level = btrfs_header_level(b);
2282 p->nodes[level] = b;
2283
2284 /*
2285 * we have a lock on b and as long as we aren't changing
2286 * the tree, there is no way to for the items in b to change.
2287 * It is safe to drop the lock on our parent before we
2288 * go through the expensive btree search on b.
2289 */
2290 btrfs_unlock_up_safe(p, level + 1);
2291
2292 ret = btrfs_bin_search(b, 0, key, &slot);
2293 if (ret < 0)
2294 goto done;
2295
2296 if (level == 0) {
2297 p->slots[level] = slot;
2298 unlock_up(p, level, lowest_unlock, 0, NULL);
2299 goto done;
2300 }
2301
2302 if (ret && slot > 0) {
2303 dec = 1;
2304 slot--;
2305 }
2306 p->slots[level] = slot;
2307 unlock_up(p, level, lowest_unlock, 0, NULL);
2308
2309 if (level == lowest_level) {
2310 if (dec)
2311 p->slots[level]++;
2312 goto done;
2313 }
2314
2315 err = read_block_for_search(root, p, &b, level, slot, key);
2316 if (err == -EAGAIN)
2317 goto again;
2318 if (err) {
2319 ret = err;
2320 goto done;
2321 }
2322
2323 level = btrfs_header_level(b);
2324 btrfs_tree_read_lock(b);
2325 b = btrfs_tree_mod_log_rewind(fs_info, p, b, time_seq);
2326 if (!b) {
2327 ret = -ENOMEM;
2328 goto done;
2329 }
2330 p->locks[level] = BTRFS_READ_LOCK;
2331 p->nodes[level] = b;
2332 }
2333 ret = 1;
2334done:
2335 if (ret < 0)
2336 btrfs_release_path(p);
2337
2338 return ret;
2339}
2340
2341/*
2342 * Search the tree again to find a leaf with smaller keys.
2343 * Returns 0 if it found something.
2344 * Returns 1 if there are no smaller keys.
2345 * Returns < 0 on error.
2346 *
2347 * This may release the path, and so you may lose any locks held at the
2348 * time you call it.
2349 */
2350static int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
2351{
2352 struct btrfs_key key;
2353 struct btrfs_key orig_key;
2354 struct btrfs_disk_key found_key;
2355 int ret;
2356
2357 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
2358 orig_key = key;
2359
2360 if (key.offset > 0) {
2361 key.offset--;
2362 } else if (key.type > 0) {
2363 key.type--;
2364 key.offset = (u64)-1;
2365 } else if (key.objectid > 0) {
2366 key.objectid--;
2367 key.type = (u8)-1;
2368 key.offset = (u64)-1;
2369 } else {
2370 return 1;
2371 }
2372
2373 btrfs_release_path(path);
2374 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2375 if (ret <= 0)
2376 return ret;
2377
2378 /*
2379 * Previous key not found. Even if we were at slot 0 of the leaf we had
2380 * before releasing the path and calling btrfs_search_slot(), we now may
2381 * be in a slot pointing to the same original key - this can happen if
2382 * after we released the path, one of more items were moved from a
2383 * sibling leaf into the front of the leaf we had due to an insertion
2384 * (see push_leaf_right()).
2385 * If we hit this case and our slot is > 0 and just decrement the slot
2386 * so that the caller does not process the same key again, which may or
2387 * may not break the caller, depending on its logic.
2388 */
2389 if (path->slots[0] < btrfs_header_nritems(path->nodes[0])) {
2390 btrfs_item_key(path->nodes[0], &found_key, path->slots[0]);
2391 ret = btrfs_comp_keys(&found_key, &orig_key);
2392 if (ret == 0) {
2393 if (path->slots[0] > 0) {
2394 path->slots[0]--;
2395 return 0;
2396 }
2397 /*
2398 * At slot 0, same key as before, it means orig_key is
2399 * the lowest, leftmost, key in the tree. We're done.
2400 */
2401 return 1;
2402 }
2403 }
2404
2405 btrfs_item_key(path->nodes[0], &found_key, 0);
2406 ret = btrfs_comp_keys(&found_key, &key);
2407 /*
2408 * We might have had an item with the previous key in the tree right
2409 * before we released our path. And after we released our path, that
2410 * item might have been pushed to the first slot (0) of the leaf we
2411 * were holding due to a tree balance. Alternatively, an item with the
2412 * previous key can exist as the only element of a leaf (big fat item).
2413 * Therefore account for these 2 cases, so that our callers (like
2414 * btrfs_previous_item) don't miss an existing item with a key matching
2415 * the previous key we computed above.
2416 */
2417 if (ret <= 0)
2418 return 0;
2419 return 1;
2420}
2421
2422/*
2423 * helper to use instead of search slot if no exact match is needed but
2424 * instead the next or previous item should be returned.
2425 * When find_higher is true, the next higher item is returned, the next lower
2426 * otherwise.
2427 * When return_any and find_higher are both true, and no higher item is found,
2428 * return the next lower instead.
2429 * When return_any is true and find_higher is false, and no lower item is found,
2430 * return the next higher instead.
2431 * It returns 0 if any item is found, 1 if none is found (tree empty), and
2432 * < 0 on error
2433 */
2434int btrfs_search_slot_for_read(struct btrfs_root *root,
2435 const struct btrfs_key *key,
2436 struct btrfs_path *p, int find_higher,
2437 int return_any)
2438{
2439 int ret;
2440 struct extent_buffer *leaf;
2441
2442again:
2443 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
2444 if (ret <= 0)
2445 return ret;
2446 /*
2447 * a return value of 1 means the path is at the position where the
2448 * item should be inserted. Normally this is the next bigger item,
2449 * but in case the previous item is the last in a leaf, path points
2450 * to the first free slot in the previous leaf, i.e. at an invalid
2451 * item.
2452 */
2453 leaf = p->nodes[0];
2454
2455 if (find_higher) {
2456 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
2457 ret = btrfs_next_leaf(root, p);
2458 if (ret <= 0)
2459 return ret;
2460 if (!return_any)
2461 return 1;
2462 /*
2463 * no higher item found, return the next
2464 * lower instead
2465 */
2466 return_any = 0;
2467 find_higher = 0;
2468 btrfs_release_path(p);
2469 goto again;
2470 }
2471 } else {
2472 if (p->slots[0] == 0) {
2473 ret = btrfs_prev_leaf(root, p);
2474 if (ret < 0)
2475 return ret;
2476 if (!ret) {
2477 leaf = p->nodes[0];
2478 if (p->slots[0] == btrfs_header_nritems(leaf))
2479 p->slots[0]--;
2480 return 0;
2481 }
2482 if (!return_any)
2483 return 1;
2484 /*
2485 * no lower item found, return the next
2486 * higher instead
2487 */
2488 return_any = 0;
2489 find_higher = 1;
2490 btrfs_release_path(p);
2491 goto again;
2492 } else {
2493 --p->slots[0];
2494 }
2495 }
2496 return 0;
2497}
2498
2499/*
2500 * Execute search and call btrfs_previous_item to traverse backwards if the item
2501 * was not found.
2502 *
2503 * Return 0 if found, 1 if not found and < 0 if error.
2504 */
2505int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key,
2506 struct btrfs_path *path)
2507{
2508 int ret;
2509
2510 ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
2511 if (ret > 0)
2512 ret = btrfs_previous_item(root, path, key->objectid, key->type);
2513
2514 if (ret == 0)
2515 btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
2516
2517 return ret;
2518}
2519
2520/*
2521 * Search for a valid slot for the given path.
2522 *
2523 * @root: The root node of the tree.
2524 * @key: Will contain a valid item if found.
2525 * @path: The starting point to validate the slot.
2526 *
2527 * Return: 0 if the item is valid
2528 * 1 if not found
2529 * <0 if error.
2530 */
2531int btrfs_get_next_valid_item(struct btrfs_root *root, struct btrfs_key *key,
2532 struct btrfs_path *path)
2533{
2534 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
2535 int ret;
2536
2537 ret = btrfs_next_leaf(root, path);
2538 if (ret)
2539 return ret;
2540 }
2541
2542 btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
2543 return 0;
2544}
2545
2546/*
2547 * adjust the pointers going up the tree, starting at level
2548 * making sure the right key of each node is points to 'key'.
2549 * This is used after shifting pointers to the left, so it stops
2550 * fixing up pointers when a given leaf/node is not in slot 0 of the
2551 * higher levels
2552 *
2553 */
2554static void fixup_low_keys(struct btrfs_trans_handle *trans,
2555 struct btrfs_path *path,
2556 struct btrfs_disk_key *key, int level)
2557{
2558 int i;
2559 struct extent_buffer *t;
2560 int ret;
2561
2562 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2563 int tslot = path->slots[i];
2564
2565 if (!path->nodes[i])
2566 break;
2567 t = path->nodes[i];
2568 ret = btrfs_tree_mod_log_insert_key(t, tslot,
2569 BTRFS_MOD_LOG_KEY_REPLACE);
2570 BUG_ON(ret < 0);
2571 btrfs_set_node_key(t, key, tslot);
2572 btrfs_mark_buffer_dirty(trans, path->nodes[i]);
2573 if (tslot != 0)
2574 break;
2575 }
2576}
2577
2578/*
2579 * update item key.
2580 *
2581 * This function isn't completely safe. It's the caller's responsibility
2582 * that the new key won't break the order
2583 */
2584void btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
2585 struct btrfs_path *path,
2586 const struct btrfs_key *new_key)
2587{
2588 struct btrfs_fs_info *fs_info = trans->fs_info;
2589 struct btrfs_disk_key disk_key;
2590 struct extent_buffer *eb;
2591 int slot;
2592
2593 eb = path->nodes[0];
2594 slot = path->slots[0];
2595 if (slot > 0) {
2596 btrfs_item_key(eb, &disk_key, slot - 1);
2597 if (unlikely(btrfs_comp_keys(&disk_key, new_key) >= 0)) {
2598 btrfs_print_leaf(eb);
2599 btrfs_crit(fs_info,
2600 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2601 slot, btrfs_disk_key_objectid(&disk_key),
2602 btrfs_disk_key_type(&disk_key),
2603 btrfs_disk_key_offset(&disk_key),
2604 new_key->objectid, new_key->type,
2605 new_key->offset);
2606 BUG();
2607 }
2608 }
2609 if (slot < btrfs_header_nritems(eb) - 1) {
2610 btrfs_item_key(eb, &disk_key, slot + 1);
2611 if (unlikely(btrfs_comp_keys(&disk_key, new_key) <= 0)) {
2612 btrfs_print_leaf(eb);
2613 btrfs_crit(fs_info,
2614 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2615 slot, btrfs_disk_key_objectid(&disk_key),
2616 btrfs_disk_key_type(&disk_key),
2617 btrfs_disk_key_offset(&disk_key),
2618 new_key->objectid, new_key->type,
2619 new_key->offset);
2620 BUG();
2621 }
2622 }
2623
2624 btrfs_cpu_key_to_disk(&disk_key, new_key);
2625 btrfs_set_item_key(eb, &disk_key, slot);
2626 btrfs_mark_buffer_dirty(trans, eb);
2627 if (slot == 0)
2628 fixup_low_keys(trans, path, &disk_key, 1);
2629}
2630
2631/*
2632 * Check key order of two sibling extent buffers.
2633 *
2634 * Return true if something is wrong.
2635 * Return false if everything is fine.
2636 *
2637 * Tree-checker only works inside one tree block, thus the following
2638 * corruption can not be detected by tree-checker:
2639 *
2640 * Leaf @left | Leaf @right
2641 * --------------------------------------------------------------
2642 * | 1 | 2 | 3 | 4 | 5 | f6 | | 7 | 8 |
2643 *
2644 * Key f6 in leaf @left itself is valid, but not valid when the next
2645 * key in leaf @right is 7.
2646 * This can only be checked at tree block merge time.
2647 * And since tree checker has ensured all key order in each tree block
2648 * is correct, we only need to bother the last key of @left and the first
2649 * key of @right.
2650 */
2651static bool check_sibling_keys(struct extent_buffer *left,
2652 struct extent_buffer *right)
2653{
2654 struct btrfs_key left_last;
2655 struct btrfs_key right_first;
2656 int level = btrfs_header_level(left);
2657 int nr_left = btrfs_header_nritems(left);
2658 int nr_right = btrfs_header_nritems(right);
2659
2660 /* No key to check in one of the tree blocks */
2661 if (!nr_left || !nr_right)
2662 return false;
2663
2664 if (level) {
2665 btrfs_node_key_to_cpu(left, &left_last, nr_left - 1);
2666 btrfs_node_key_to_cpu(right, &right_first, 0);
2667 } else {
2668 btrfs_item_key_to_cpu(left, &left_last, nr_left - 1);
2669 btrfs_item_key_to_cpu(right, &right_first, 0);
2670 }
2671
2672 if (unlikely(btrfs_comp_cpu_keys(&left_last, &right_first) >= 0)) {
2673 btrfs_crit(left->fs_info, "left extent buffer:");
2674 btrfs_print_tree(left, false);
2675 btrfs_crit(left->fs_info, "right extent buffer:");
2676 btrfs_print_tree(right, false);
2677 btrfs_crit(left->fs_info,
2678"bad key order, sibling blocks, left last (%llu %u %llu) right first (%llu %u %llu)",
2679 left_last.objectid, left_last.type,
2680 left_last.offset, right_first.objectid,
2681 right_first.type, right_first.offset);
2682 return true;
2683 }
2684 return false;
2685}
2686
2687/*
2688 * try to push data from one node into the next node left in the
2689 * tree.
2690 *
2691 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2692 * error, and > 0 if there was no room in the left hand block.
2693 */
2694static int push_node_left(struct btrfs_trans_handle *trans,
2695 struct extent_buffer *dst,
2696 struct extent_buffer *src, int empty)
2697{
2698 struct btrfs_fs_info *fs_info = trans->fs_info;
2699 int push_items = 0;
2700 int src_nritems;
2701 int dst_nritems;
2702 int ret = 0;
2703
2704 src_nritems = btrfs_header_nritems(src);
2705 dst_nritems = btrfs_header_nritems(dst);
2706 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2707 WARN_ON(btrfs_header_generation(src) != trans->transid);
2708 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2709
2710 if (!empty && src_nritems <= 8)
2711 return 1;
2712
2713 if (push_items <= 0)
2714 return 1;
2715
2716 if (empty) {
2717 push_items = min(src_nritems, push_items);
2718 if (push_items < src_nritems) {
2719 /* leave at least 8 pointers in the node if
2720 * we aren't going to empty it
2721 */
2722 if (src_nritems - push_items < 8) {
2723 if (push_items <= 8)
2724 return 1;
2725 push_items -= 8;
2726 }
2727 }
2728 } else
2729 push_items = min(src_nritems - 8, push_items);
2730
2731 /* dst is the left eb, src is the middle eb */
2732 if (check_sibling_keys(dst, src)) {
2733 ret = -EUCLEAN;
2734 btrfs_abort_transaction(trans, ret);
2735 return ret;
2736 }
2737 ret = btrfs_tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
2738 if (ret) {
2739 btrfs_abort_transaction(trans, ret);
2740 return ret;
2741 }
2742 copy_extent_buffer(dst, src,
2743 btrfs_node_key_ptr_offset(dst, dst_nritems),
2744 btrfs_node_key_ptr_offset(src, 0),
2745 push_items * sizeof(struct btrfs_key_ptr));
2746
2747 if (push_items < src_nritems) {
2748 /*
2749 * btrfs_tree_mod_log_eb_copy handles logging the move, so we
2750 * don't need to do an explicit tree mod log operation for it.
2751 */
2752 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(src, 0),
2753 btrfs_node_key_ptr_offset(src, push_items),
2754 (src_nritems - push_items) *
2755 sizeof(struct btrfs_key_ptr));
2756 }
2757 btrfs_set_header_nritems(src, src_nritems - push_items);
2758 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2759 btrfs_mark_buffer_dirty(trans, src);
2760 btrfs_mark_buffer_dirty(trans, dst);
2761
2762 return ret;
2763}
2764
2765/*
2766 * try to push data from one node into the next node right in the
2767 * tree.
2768 *
2769 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
2770 * error, and > 0 if there was no room in the right hand block.
2771 *
2772 * this will only push up to 1/2 the contents of the left node over
2773 */
2774static int balance_node_right(struct btrfs_trans_handle *trans,
2775 struct extent_buffer *dst,
2776 struct extent_buffer *src)
2777{
2778 struct btrfs_fs_info *fs_info = trans->fs_info;
2779 int push_items = 0;
2780 int max_push;
2781 int src_nritems;
2782 int dst_nritems;
2783 int ret = 0;
2784
2785 WARN_ON(btrfs_header_generation(src) != trans->transid);
2786 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2787
2788 src_nritems = btrfs_header_nritems(src);
2789 dst_nritems = btrfs_header_nritems(dst);
2790 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2791 if (push_items <= 0)
2792 return 1;
2793
2794 if (src_nritems < 4)
2795 return 1;
2796
2797 max_push = src_nritems / 2 + 1;
2798 /* don't try to empty the node */
2799 if (max_push >= src_nritems)
2800 return 1;
2801
2802 if (max_push < push_items)
2803 push_items = max_push;
2804
2805 /* dst is the right eb, src is the middle eb */
2806 if (check_sibling_keys(src, dst)) {
2807 ret = -EUCLEAN;
2808 btrfs_abort_transaction(trans, ret);
2809 return ret;
2810 }
2811
2812 /*
2813 * btrfs_tree_mod_log_eb_copy handles logging the move, so we don't
2814 * need to do an explicit tree mod log operation for it.
2815 */
2816 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(dst, push_items),
2817 btrfs_node_key_ptr_offset(dst, 0),
2818 (dst_nritems) *
2819 sizeof(struct btrfs_key_ptr));
2820
2821 ret = btrfs_tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
2822 push_items);
2823 if (ret) {
2824 btrfs_abort_transaction(trans, ret);
2825 return ret;
2826 }
2827 copy_extent_buffer(dst, src,
2828 btrfs_node_key_ptr_offset(dst, 0),
2829 btrfs_node_key_ptr_offset(src, src_nritems - push_items),
2830 push_items * sizeof(struct btrfs_key_ptr));
2831
2832 btrfs_set_header_nritems(src, src_nritems - push_items);
2833 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2834
2835 btrfs_mark_buffer_dirty(trans, src);
2836 btrfs_mark_buffer_dirty(trans, dst);
2837
2838 return ret;
2839}
2840
2841/*
2842 * helper function to insert a new root level in the tree.
2843 * A new node is allocated, and a single item is inserted to
2844 * point to the existing root
2845 *
2846 * returns zero on success or < 0 on failure.
2847 */
2848static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2849 struct btrfs_root *root,
2850 struct btrfs_path *path, int level)
2851{
2852 u64 lower_gen;
2853 struct extent_buffer *lower;
2854 struct extent_buffer *c;
2855 struct extent_buffer *old;
2856 struct btrfs_disk_key lower_key;
2857 int ret;
2858
2859 BUG_ON(path->nodes[level]);
2860 BUG_ON(path->nodes[level-1] != root->node);
2861
2862 lower = path->nodes[level-1];
2863 if (level == 1)
2864 btrfs_item_key(lower, &lower_key, 0);
2865 else
2866 btrfs_node_key(lower, &lower_key, 0);
2867
2868 c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
2869 &lower_key, level, root->node->start, 0,
2870 0, BTRFS_NESTING_NEW_ROOT);
2871 if (IS_ERR(c))
2872 return PTR_ERR(c);
2873
2874 root_add_used_bytes(root);
2875
2876 btrfs_set_header_nritems(c, 1);
2877 btrfs_set_node_key(c, &lower_key, 0);
2878 btrfs_set_node_blockptr(c, 0, lower->start);
2879 lower_gen = btrfs_header_generation(lower);
2880 WARN_ON(lower_gen != trans->transid);
2881
2882 btrfs_set_node_ptr_generation(c, 0, lower_gen);
2883
2884 btrfs_mark_buffer_dirty(trans, c);
2885
2886 old = root->node;
2887 ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
2888 if (ret < 0) {
2889 btrfs_free_tree_block(trans, btrfs_root_id(root), c, 0, 1);
2890 btrfs_tree_unlock(c);
2891 free_extent_buffer(c);
2892 return ret;
2893 }
2894 rcu_assign_pointer(root->node, c);
2895
2896 /* the super has an extra ref to root->node */
2897 free_extent_buffer(old);
2898
2899 add_root_to_dirty_list(root);
2900 atomic_inc(&c->refs);
2901 path->nodes[level] = c;
2902 path->locks[level] = BTRFS_WRITE_LOCK;
2903 path->slots[level] = 0;
2904 return 0;
2905}
2906
2907/*
2908 * worker function to insert a single pointer in a node.
2909 * the node should have enough room for the pointer already
2910 *
2911 * slot and level indicate where you want the key to go, and
2912 * blocknr is the block the key points to.
2913 */
2914static int insert_ptr(struct btrfs_trans_handle *trans,
2915 struct btrfs_path *path,
2916 struct btrfs_disk_key *key, u64 bytenr,
2917 int slot, int level)
2918{
2919 struct extent_buffer *lower;
2920 int nritems;
2921 int ret;
2922
2923 BUG_ON(!path->nodes[level]);
2924 btrfs_assert_tree_write_locked(path->nodes[level]);
2925 lower = path->nodes[level];
2926 nritems = btrfs_header_nritems(lower);
2927 BUG_ON(slot > nritems);
2928 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
2929 if (slot != nritems) {
2930 if (level) {
2931 ret = btrfs_tree_mod_log_insert_move(lower, slot + 1,
2932 slot, nritems - slot);
2933 if (ret < 0) {
2934 btrfs_abort_transaction(trans, ret);
2935 return ret;
2936 }
2937 }
2938 memmove_extent_buffer(lower,
2939 btrfs_node_key_ptr_offset(lower, slot + 1),
2940 btrfs_node_key_ptr_offset(lower, slot),
2941 (nritems - slot) * sizeof(struct btrfs_key_ptr));
2942 }
2943 if (level) {
2944 ret = btrfs_tree_mod_log_insert_key(lower, slot,
2945 BTRFS_MOD_LOG_KEY_ADD);
2946 if (ret < 0) {
2947 btrfs_abort_transaction(trans, ret);
2948 return ret;
2949 }
2950 }
2951 btrfs_set_node_key(lower, key, slot);
2952 btrfs_set_node_blockptr(lower, slot, bytenr);
2953 WARN_ON(trans->transid == 0);
2954 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
2955 btrfs_set_header_nritems(lower, nritems + 1);
2956 btrfs_mark_buffer_dirty(trans, lower);
2957
2958 return 0;
2959}
2960
2961/*
2962 * split the node at the specified level in path in two.
2963 * The path is corrected to point to the appropriate node after the split
2964 *
2965 * Before splitting this tries to make some room in the node by pushing
2966 * left and right, if either one works, it returns right away.
2967 *
2968 * returns 0 on success and < 0 on failure
2969 */
2970static noinline int split_node(struct btrfs_trans_handle *trans,
2971 struct btrfs_root *root,
2972 struct btrfs_path *path, int level)
2973{
2974 struct btrfs_fs_info *fs_info = root->fs_info;
2975 struct extent_buffer *c;
2976 struct extent_buffer *split;
2977 struct btrfs_disk_key disk_key;
2978 int mid;
2979 int ret;
2980 u32 c_nritems;
2981
2982 c = path->nodes[level];
2983 WARN_ON(btrfs_header_generation(c) != trans->transid);
2984 if (c == root->node) {
2985 /*
2986 * trying to split the root, lets make a new one
2987 *
2988 * tree mod log: We don't log_removal old root in
2989 * insert_new_root, because that root buffer will be kept as a
2990 * normal node. We are going to log removal of half of the
2991 * elements below with btrfs_tree_mod_log_eb_copy(). We're
2992 * holding a tree lock on the buffer, which is why we cannot
2993 * race with other tree_mod_log users.
2994 */
2995 ret = insert_new_root(trans, root, path, level + 1);
2996 if (ret)
2997 return ret;
2998 } else {
2999 ret = push_nodes_for_insert(trans, root, path, level);
3000 c = path->nodes[level];
3001 if (!ret && btrfs_header_nritems(c) <
3002 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
3003 return 0;
3004 if (ret < 0)
3005 return ret;
3006 }
3007
3008 c_nritems = btrfs_header_nritems(c);
3009 mid = (c_nritems + 1) / 2;
3010 btrfs_node_key(c, &disk_key, mid);
3011
3012 split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
3013 &disk_key, level, c->start, 0,
3014 0, BTRFS_NESTING_SPLIT);
3015 if (IS_ERR(split))
3016 return PTR_ERR(split);
3017
3018 root_add_used_bytes(root);
3019 ASSERT(btrfs_header_level(c) == level);
3020
3021 ret = btrfs_tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
3022 if (ret) {
3023 btrfs_tree_unlock(split);
3024 free_extent_buffer(split);
3025 btrfs_abort_transaction(trans, ret);
3026 return ret;
3027 }
3028 copy_extent_buffer(split, c,
3029 btrfs_node_key_ptr_offset(split, 0),
3030 btrfs_node_key_ptr_offset(c, mid),
3031 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3032 btrfs_set_header_nritems(split, c_nritems - mid);
3033 btrfs_set_header_nritems(c, mid);
3034
3035 btrfs_mark_buffer_dirty(trans, c);
3036 btrfs_mark_buffer_dirty(trans, split);
3037
3038 ret = insert_ptr(trans, path, &disk_key, split->start,
3039 path->slots[level + 1] + 1, level + 1);
3040 if (ret < 0) {
3041 btrfs_tree_unlock(split);
3042 free_extent_buffer(split);
3043 return ret;
3044 }
3045
3046 if (path->slots[level] >= mid) {
3047 path->slots[level] -= mid;
3048 btrfs_tree_unlock(c);
3049 free_extent_buffer(c);
3050 path->nodes[level] = split;
3051 path->slots[level + 1] += 1;
3052 } else {
3053 btrfs_tree_unlock(split);
3054 free_extent_buffer(split);
3055 }
3056 return 0;
3057}
3058
3059/*
3060 * how many bytes are required to store the items in a leaf. start
3061 * and nr indicate which items in the leaf to check. This totals up the
3062 * space used both by the item structs and the item data
3063 */
3064static int leaf_space_used(const struct extent_buffer *l, int start, int nr)
3065{
3066 int data_len;
3067 int nritems = btrfs_header_nritems(l);
3068 int end = min(nritems, start + nr) - 1;
3069
3070 if (!nr)
3071 return 0;
3072 data_len = btrfs_item_offset(l, start) + btrfs_item_size(l, start);
3073 data_len = data_len - btrfs_item_offset(l, end);
3074 data_len += sizeof(struct btrfs_item) * nr;
3075 WARN_ON(data_len < 0);
3076 return data_len;
3077}
3078
3079/*
3080 * The space between the end of the leaf items and
3081 * the start of the leaf data. IOW, how much room
3082 * the leaf has left for both items and data
3083 */
3084int btrfs_leaf_free_space(const struct extent_buffer *leaf)
3085{
3086 struct btrfs_fs_info *fs_info = leaf->fs_info;
3087 int nritems = btrfs_header_nritems(leaf);
3088 int ret;
3089
3090 ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
3091 if (ret < 0) {
3092 btrfs_crit(fs_info,
3093 "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3094 ret,
3095 (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
3096 leaf_space_used(leaf, 0, nritems), nritems);
3097 }
3098 return ret;
3099}
3100
3101/*
3102 * min slot controls the lowest index we're willing to push to the
3103 * right. We'll push up to and including min_slot, but no lower
3104 */
3105static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
3106 struct btrfs_path *path,
3107 int data_size, int empty,
3108 struct extent_buffer *right,
3109 int free_space, u32 left_nritems,
3110 u32 min_slot)
3111{
3112 struct btrfs_fs_info *fs_info = right->fs_info;
3113 struct extent_buffer *left = path->nodes[0];
3114 struct extent_buffer *upper = path->nodes[1];
3115 struct btrfs_map_token token;
3116 struct btrfs_disk_key disk_key;
3117 int slot;
3118 u32 i;
3119 int push_space = 0;
3120 int push_items = 0;
3121 u32 nr;
3122 u32 right_nritems;
3123 u32 data_end;
3124 u32 this_item_size;
3125
3126 if (empty)
3127 nr = 0;
3128 else
3129 nr = max_t(u32, 1, min_slot);
3130
3131 if (path->slots[0] >= left_nritems)
3132 push_space += data_size;
3133
3134 slot = path->slots[1];
3135 i = left_nritems - 1;
3136 while (i >= nr) {
3137 if (!empty && push_items > 0) {
3138 if (path->slots[0] > i)
3139 break;
3140 if (path->slots[0] == i) {
3141 int space = btrfs_leaf_free_space(left);
3142
3143 if (space + push_space * 2 > free_space)
3144 break;
3145 }
3146 }
3147
3148 if (path->slots[0] == i)
3149 push_space += data_size;
3150
3151 this_item_size = btrfs_item_size(left, i);
3152 if (this_item_size + sizeof(struct btrfs_item) +
3153 push_space > free_space)
3154 break;
3155
3156 push_items++;
3157 push_space += this_item_size + sizeof(struct btrfs_item);
3158 if (i == 0)
3159 break;
3160 i--;
3161 }
3162
3163 if (push_items == 0)
3164 goto out_unlock;
3165
3166 WARN_ON(!empty && push_items == left_nritems);
3167
3168 /* push left to right */
3169 right_nritems = btrfs_header_nritems(right);
3170
3171 push_space = btrfs_item_data_end(left, left_nritems - push_items);
3172 push_space -= leaf_data_end(left);
3173
3174 /* make room in the right data area */
3175 data_end = leaf_data_end(right);
3176 memmove_leaf_data(right, data_end - push_space, data_end,
3177 BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
3178
3179 /* copy from the left data area */
3180 copy_leaf_data(right, left, BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3181 leaf_data_end(left), push_space);
3182
3183 memmove_leaf_items(right, push_items, 0, right_nritems);
3184
3185 /* copy the items from left to right */
3186 copy_leaf_items(right, left, 0, left_nritems - push_items, push_items);
3187
3188 /* update the item pointers */
3189 btrfs_init_map_token(&token, right);
3190 right_nritems += push_items;
3191 btrfs_set_header_nritems(right, right_nritems);
3192 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3193 for (i = 0; i < right_nritems; i++) {
3194 push_space -= btrfs_token_item_size(&token, i);
3195 btrfs_set_token_item_offset(&token, i, push_space);
3196 }
3197
3198 left_nritems -= push_items;
3199 btrfs_set_header_nritems(left, left_nritems);
3200
3201 if (left_nritems)
3202 btrfs_mark_buffer_dirty(trans, left);
3203 else
3204 btrfs_clear_buffer_dirty(trans, left);
3205
3206 btrfs_mark_buffer_dirty(trans, right);
3207
3208 btrfs_item_key(right, &disk_key, 0);
3209 btrfs_set_node_key(upper, &disk_key, slot + 1);
3210 btrfs_mark_buffer_dirty(trans, upper);
3211
3212 /* then fixup the leaf pointer in the path */
3213 if (path->slots[0] >= left_nritems) {
3214 path->slots[0] -= left_nritems;
3215 if (btrfs_header_nritems(path->nodes[0]) == 0)
3216 btrfs_clear_buffer_dirty(trans, path->nodes[0]);
3217 btrfs_tree_unlock(path->nodes[0]);
3218 free_extent_buffer(path->nodes[0]);
3219 path->nodes[0] = right;
3220 path->slots[1] += 1;
3221 } else {
3222 btrfs_tree_unlock(right);
3223 free_extent_buffer(right);
3224 }
3225 return 0;
3226
3227out_unlock:
3228 btrfs_tree_unlock(right);
3229 free_extent_buffer(right);
3230 return 1;
3231}
3232
3233/*
3234 * push some data in the path leaf to the right, trying to free up at
3235 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3236 *
3237 * returns 1 if the push failed because the other node didn't have enough
3238 * room, 0 if everything worked out and < 0 if there were major errors.
3239 *
3240 * this will push starting from min_slot to the end of the leaf. It won't
3241 * push any slot lower than min_slot
3242 */
3243static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3244 *root, struct btrfs_path *path,
3245 int min_data_size, int data_size,
3246 int empty, u32 min_slot)
3247{
3248 struct extent_buffer *left = path->nodes[0];
3249 struct extent_buffer *right;
3250 struct extent_buffer *upper;
3251 int slot;
3252 int free_space;
3253 u32 left_nritems;
3254 int ret;
3255
3256 if (!path->nodes[1])
3257 return 1;
3258
3259 slot = path->slots[1];
3260 upper = path->nodes[1];
3261 if (slot >= btrfs_header_nritems(upper) - 1)
3262 return 1;
3263
3264 btrfs_assert_tree_write_locked(path->nodes[1]);
3265
3266 right = btrfs_read_node_slot(upper, slot + 1);
3267 if (IS_ERR(right))
3268 return PTR_ERR(right);
3269
3270 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
3271
3272 free_space = btrfs_leaf_free_space(right);
3273 if (free_space < data_size)
3274 goto out_unlock;
3275
3276 ret = btrfs_cow_block(trans, root, right, upper,
3277 slot + 1, &right, BTRFS_NESTING_RIGHT_COW);
3278 if (ret)
3279 goto out_unlock;
3280
3281 left_nritems = btrfs_header_nritems(left);
3282 if (left_nritems == 0)
3283 goto out_unlock;
3284
3285 if (check_sibling_keys(left, right)) {
3286 ret = -EUCLEAN;
3287 btrfs_abort_transaction(trans, ret);
3288 btrfs_tree_unlock(right);
3289 free_extent_buffer(right);
3290 return ret;
3291 }
3292 if (path->slots[0] == left_nritems && !empty) {
3293 /* Key greater than all keys in the leaf, right neighbor has
3294 * enough room for it and we're not emptying our leaf to delete
3295 * it, therefore use right neighbor to insert the new item and
3296 * no need to touch/dirty our left leaf. */
3297 btrfs_tree_unlock(left);
3298 free_extent_buffer(left);
3299 path->nodes[0] = right;
3300 path->slots[0] = 0;
3301 path->slots[1]++;
3302 return 0;
3303 }
3304
3305 return __push_leaf_right(trans, path, min_data_size, empty, right,
3306 free_space, left_nritems, min_slot);
3307out_unlock:
3308 btrfs_tree_unlock(right);
3309 free_extent_buffer(right);
3310 return 1;
3311}
3312
3313/*
3314 * push some data in the path leaf to the left, trying to free up at
3315 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3316 *
3317 * max_slot can put a limit on how far into the leaf we'll push items. The
3318 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3319 * items
3320 */
3321static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
3322 struct btrfs_path *path, int data_size,
3323 int empty, struct extent_buffer *left,
3324 int free_space, u32 right_nritems,
3325 u32 max_slot)
3326{
3327 struct btrfs_fs_info *fs_info = left->fs_info;
3328 struct btrfs_disk_key disk_key;
3329 struct extent_buffer *right = path->nodes[0];
3330 int i;
3331 int push_space = 0;
3332 int push_items = 0;
3333 u32 old_left_nritems;
3334 u32 nr;
3335 int ret = 0;
3336 u32 this_item_size;
3337 u32 old_left_item_size;
3338 struct btrfs_map_token token;
3339
3340 if (empty)
3341 nr = min(right_nritems, max_slot);
3342 else
3343 nr = min(right_nritems - 1, max_slot);
3344
3345 for (i = 0; i < nr; i++) {
3346 if (!empty && push_items > 0) {
3347 if (path->slots[0] < i)
3348 break;
3349 if (path->slots[0] == i) {
3350 int space = btrfs_leaf_free_space(right);
3351
3352 if (space + push_space * 2 > free_space)
3353 break;
3354 }
3355 }
3356
3357 if (path->slots[0] == i)
3358 push_space += data_size;
3359
3360 this_item_size = btrfs_item_size(right, i);
3361 if (this_item_size + sizeof(struct btrfs_item) + push_space >
3362 free_space)
3363 break;
3364
3365 push_items++;
3366 push_space += this_item_size + sizeof(struct btrfs_item);
3367 }
3368
3369 if (push_items == 0) {
3370 ret = 1;
3371 goto out;
3372 }
3373 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3374
3375 /* push data from right to left */
3376 copy_leaf_items(left, right, btrfs_header_nritems(left), 0, push_items);
3377
3378 push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3379 btrfs_item_offset(right, push_items - 1);
3380
3381 copy_leaf_data(left, right, leaf_data_end(left) - push_space,
3382 btrfs_item_offset(right, push_items - 1), push_space);
3383 old_left_nritems = btrfs_header_nritems(left);
3384 BUG_ON(old_left_nritems <= 0);
3385
3386 btrfs_init_map_token(&token, left);
3387 old_left_item_size = btrfs_item_offset(left, old_left_nritems - 1);
3388 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3389 u32 ioff;
3390
3391 ioff = btrfs_token_item_offset(&token, i);
3392 btrfs_set_token_item_offset(&token, i,
3393 ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size));
3394 }
3395 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3396
3397 /* fixup right node */
3398 if (push_items > right_nritems)
3399 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3400 right_nritems);
3401
3402 if (push_items < right_nritems) {
3403 push_space = btrfs_item_offset(right, push_items - 1) -
3404 leaf_data_end(right);
3405 memmove_leaf_data(right,
3406 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3407 leaf_data_end(right), push_space);
3408
3409 memmove_leaf_items(right, 0, push_items,
3410 btrfs_header_nritems(right) - push_items);
3411 }
3412
3413 btrfs_init_map_token(&token, right);
3414 right_nritems -= push_items;
3415 btrfs_set_header_nritems(right, right_nritems);
3416 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3417 for (i = 0; i < right_nritems; i++) {
3418 push_space = push_space - btrfs_token_item_size(&token, i);
3419 btrfs_set_token_item_offset(&token, i, push_space);
3420 }
3421
3422 btrfs_mark_buffer_dirty(trans, left);
3423 if (right_nritems)
3424 btrfs_mark_buffer_dirty(trans, right);
3425 else
3426 btrfs_clear_buffer_dirty(trans, right);
3427
3428 btrfs_item_key(right, &disk_key, 0);
3429 fixup_low_keys(trans, path, &disk_key, 1);
3430
3431 /* then fixup the leaf pointer in the path */
3432 if (path->slots[0] < push_items) {
3433 path->slots[0] += old_left_nritems;
3434 btrfs_tree_unlock(path->nodes[0]);
3435 free_extent_buffer(path->nodes[0]);
3436 path->nodes[0] = left;
3437 path->slots[1] -= 1;
3438 } else {
3439 btrfs_tree_unlock(left);
3440 free_extent_buffer(left);
3441 path->slots[0] -= push_items;
3442 }
3443 BUG_ON(path->slots[0] < 0);
3444 return ret;
3445out:
3446 btrfs_tree_unlock(left);
3447 free_extent_buffer(left);
3448 return ret;
3449}
3450
3451/*
3452 * push some data in the path leaf to the left, trying to free up at
3453 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3454 *
3455 * max_slot can put a limit on how far into the leaf we'll push items. The
3456 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3457 * items
3458 */
3459static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3460 *root, struct btrfs_path *path, int min_data_size,
3461 int data_size, int empty, u32 max_slot)
3462{
3463 struct extent_buffer *right = path->nodes[0];
3464 struct extent_buffer *left;
3465 int slot;
3466 int free_space;
3467 u32 right_nritems;
3468 int ret = 0;
3469
3470 slot = path->slots[1];
3471 if (slot == 0)
3472 return 1;
3473 if (!path->nodes[1])
3474 return 1;
3475
3476 right_nritems = btrfs_header_nritems(right);
3477 if (right_nritems == 0)
3478 return 1;
3479
3480 btrfs_assert_tree_write_locked(path->nodes[1]);
3481
3482 left = btrfs_read_node_slot(path->nodes[1], slot - 1);
3483 if (IS_ERR(left))
3484 return PTR_ERR(left);
3485
3486 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
3487
3488 free_space = btrfs_leaf_free_space(left);
3489 if (free_space < data_size) {
3490 ret = 1;
3491 goto out;
3492 }
3493
3494 ret = btrfs_cow_block(trans, root, left,
3495 path->nodes[1], slot - 1, &left,
3496 BTRFS_NESTING_LEFT_COW);
3497 if (ret) {
3498 /* we hit -ENOSPC, but it isn't fatal here */
3499 if (ret == -ENOSPC)
3500 ret = 1;
3501 goto out;
3502 }
3503
3504 if (check_sibling_keys(left, right)) {
3505 ret = -EUCLEAN;
3506 btrfs_abort_transaction(trans, ret);
3507 goto out;
3508 }
3509 return __push_leaf_left(trans, path, min_data_size, empty, left,
3510 free_space, right_nritems, max_slot);
3511out:
3512 btrfs_tree_unlock(left);
3513 free_extent_buffer(left);
3514 return ret;
3515}
3516
3517/*
3518 * split the path's leaf in two, making sure there is at least data_size
3519 * available for the resulting leaf level of the path.
3520 */
3521static noinline int copy_for_split(struct btrfs_trans_handle *trans,
3522 struct btrfs_path *path,
3523 struct extent_buffer *l,
3524 struct extent_buffer *right,
3525 int slot, int mid, int nritems)
3526{
3527 struct btrfs_fs_info *fs_info = trans->fs_info;
3528 int data_copy_size;
3529 int rt_data_off;
3530 int i;
3531 int ret;
3532 struct btrfs_disk_key disk_key;
3533 struct btrfs_map_token token;
3534
3535 nritems = nritems - mid;
3536 btrfs_set_header_nritems(right, nritems);
3537 data_copy_size = btrfs_item_data_end(l, mid) - leaf_data_end(l);
3538
3539 copy_leaf_items(right, l, 0, mid, nritems);
3540
3541 copy_leaf_data(right, l, BTRFS_LEAF_DATA_SIZE(fs_info) - data_copy_size,
3542 leaf_data_end(l), data_copy_size);
3543
3544 rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_data_end(l, mid);
3545
3546 btrfs_init_map_token(&token, right);
3547 for (i = 0; i < nritems; i++) {
3548 u32 ioff;
3549
3550 ioff = btrfs_token_item_offset(&token, i);
3551 btrfs_set_token_item_offset(&token, i, ioff + rt_data_off);
3552 }
3553
3554 btrfs_set_header_nritems(l, mid);
3555 btrfs_item_key(right, &disk_key, 0);
3556 ret = insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
3557 if (ret < 0)
3558 return ret;
3559
3560 btrfs_mark_buffer_dirty(trans, right);
3561 btrfs_mark_buffer_dirty(trans, l);
3562 BUG_ON(path->slots[0] != slot);
3563
3564 if (mid <= slot) {
3565 btrfs_tree_unlock(path->nodes[0]);
3566 free_extent_buffer(path->nodes[0]);
3567 path->nodes[0] = right;
3568 path->slots[0] -= mid;
3569 path->slots[1] += 1;
3570 } else {
3571 btrfs_tree_unlock(right);
3572 free_extent_buffer(right);
3573 }
3574
3575 BUG_ON(path->slots[0] < 0);
3576
3577 return 0;
3578}
3579
3580/*
3581 * double splits happen when we need to insert a big item in the middle
3582 * of a leaf. A double split can leave us with 3 mostly empty leaves:
3583 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
3584 * A B C
3585 *
3586 * We avoid this by trying to push the items on either side of our target
3587 * into the adjacent leaves. If all goes well we can avoid the double split
3588 * completely.
3589 */
3590static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
3591 struct btrfs_root *root,
3592 struct btrfs_path *path,
3593 int data_size)
3594{
3595 int ret;
3596 int progress = 0;
3597 int slot;
3598 u32 nritems;
3599 int space_needed = data_size;
3600
3601 slot = path->slots[0];
3602 if (slot < btrfs_header_nritems(path->nodes[0]))
3603 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3604
3605 /*
3606 * try to push all the items after our slot into the
3607 * right leaf
3608 */
3609 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
3610 if (ret < 0)
3611 return ret;
3612
3613 if (ret == 0)
3614 progress++;
3615
3616 nritems = btrfs_header_nritems(path->nodes[0]);
3617 /*
3618 * our goal is to get our slot at the start or end of a leaf. If
3619 * we've done so we're done
3620 */
3621 if (path->slots[0] == 0 || path->slots[0] == nritems)
3622 return 0;
3623
3624 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3625 return 0;
3626
3627 /* try to push all the items before our slot into the next leaf */
3628 slot = path->slots[0];
3629 space_needed = data_size;
3630 if (slot > 0)
3631 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3632 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
3633 if (ret < 0)
3634 return ret;
3635
3636 if (ret == 0)
3637 progress++;
3638
3639 if (progress)
3640 return 0;
3641 return 1;
3642}
3643
3644/*
3645 * split the path's leaf in two, making sure there is at least data_size
3646 * available for the resulting leaf level of the path.
3647 *
3648 * returns 0 if all went well and < 0 on failure.
3649 */
3650static noinline int split_leaf(struct btrfs_trans_handle *trans,
3651 struct btrfs_root *root,
3652 const struct btrfs_key *ins_key,
3653 struct btrfs_path *path, int data_size,
3654 int extend)
3655{
3656 struct btrfs_disk_key disk_key;
3657 struct extent_buffer *l;
3658 u32 nritems;
3659 int mid;
3660 int slot;
3661 struct extent_buffer *right;
3662 struct btrfs_fs_info *fs_info = root->fs_info;
3663 int ret = 0;
3664 int wret;
3665 int split;
3666 int num_doubles = 0;
3667 int tried_avoid_double = 0;
3668
3669 l = path->nodes[0];
3670 slot = path->slots[0];
3671 if (extend && data_size + btrfs_item_size(l, slot) +
3672 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
3673 return -EOVERFLOW;
3674
3675 /* first try to make some room by pushing left and right */
3676 if (data_size && path->nodes[1]) {
3677 int space_needed = data_size;
3678
3679 if (slot < btrfs_header_nritems(l))
3680 space_needed -= btrfs_leaf_free_space(l);
3681
3682 wret = push_leaf_right(trans, root, path, space_needed,
3683 space_needed, 0, 0);
3684 if (wret < 0)
3685 return wret;
3686 if (wret) {
3687 space_needed = data_size;
3688 if (slot > 0)
3689 space_needed -= btrfs_leaf_free_space(l);
3690 wret = push_leaf_left(trans, root, path, space_needed,
3691 space_needed, 0, (u32)-1);
3692 if (wret < 0)
3693 return wret;
3694 }
3695 l = path->nodes[0];
3696
3697 /* did the pushes work? */
3698 if (btrfs_leaf_free_space(l) >= data_size)
3699 return 0;
3700 }
3701
3702 if (!path->nodes[1]) {
3703 ret = insert_new_root(trans, root, path, 1);
3704 if (ret)
3705 return ret;
3706 }
3707again:
3708 split = 1;
3709 l = path->nodes[0];
3710 slot = path->slots[0];
3711 nritems = btrfs_header_nritems(l);
3712 mid = (nritems + 1) / 2;
3713
3714 if (mid <= slot) {
3715 if (nritems == 1 ||
3716 leaf_space_used(l, mid, nritems - mid) + data_size >
3717 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3718 if (slot >= nritems) {
3719 split = 0;
3720 } else {
3721 mid = slot;
3722 if (mid != nritems &&
3723 leaf_space_used(l, mid, nritems - mid) +
3724 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3725 if (data_size && !tried_avoid_double)
3726 goto push_for_double;
3727 split = 2;
3728 }
3729 }
3730 }
3731 } else {
3732 if (leaf_space_used(l, 0, mid) + data_size >
3733 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3734 if (!extend && data_size && slot == 0) {
3735 split = 0;
3736 } else if ((extend || !data_size) && slot == 0) {
3737 mid = 1;
3738 } else {
3739 mid = slot;
3740 if (mid != nritems &&
3741 leaf_space_used(l, mid, nritems - mid) +
3742 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3743 if (data_size && !tried_avoid_double)
3744 goto push_for_double;
3745 split = 2;
3746 }
3747 }
3748 }
3749 }
3750
3751 if (split == 0)
3752 btrfs_cpu_key_to_disk(&disk_key, ins_key);
3753 else
3754 btrfs_item_key(l, &disk_key, mid);
3755
3756 /*
3757 * We have to about BTRFS_NESTING_NEW_ROOT here if we've done a double
3758 * split, because we're only allowed to have MAX_LOCKDEP_SUBCLASSES
3759 * subclasses, which is 8 at the time of this patch, and we've maxed it
3760 * out. In the future we could add a
3761 * BTRFS_NESTING_SPLIT_THE_SPLITTENING if we need to, but for now just
3762 * use BTRFS_NESTING_NEW_ROOT.
3763 */
3764 right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
3765 &disk_key, 0, l->start, 0, 0,
3766 num_doubles ? BTRFS_NESTING_NEW_ROOT :
3767 BTRFS_NESTING_SPLIT);
3768 if (IS_ERR(right))
3769 return PTR_ERR(right);
3770
3771 root_add_used_bytes(root);
3772
3773 if (split == 0) {
3774 if (mid <= slot) {
3775 btrfs_set_header_nritems(right, 0);
3776 ret = insert_ptr(trans, path, &disk_key,
3777 right->start, path->slots[1] + 1, 1);
3778 if (ret < 0) {
3779 btrfs_tree_unlock(right);
3780 free_extent_buffer(right);
3781 return ret;
3782 }
3783 btrfs_tree_unlock(path->nodes[0]);
3784 free_extent_buffer(path->nodes[0]);
3785 path->nodes[0] = right;
3786 path->slots[0] = 0;
3787 path->slots[1] += 1;
3788 } else {
3789 btrfs_set_header_nritems(right, 0);
3790 ret = insert_ptr(trans, path, &disk_key,
3791 right->start, path->slots[1], 1);
3792 if (ret < 0) {
3793 btrfs_tree_unlock(right);
3794 free_extent_buffer(right);
3795 return ret;
3796 }
3797 btrfs_tree_unlock(path->nodes[0]);
3798 free_extent_buffer(path->nodes[0]);
3799 path->nodes[0] = right;
3800 path->slots[0] = 0;
3801 if (path->slots[1] == 0)
3802 fixup_low_keys(trans, path, &disk_key, 1);
3803 }
3804 /*
3805 * We create a new leaf 'right' for the required ins_len and
3806 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
3807 * the content of ins_len to 'right'.
3808 */
3809 return ret;
3810 }
3811
3812 ret = copy_for_split(trans, path, l, right, slot, mid, nritems);
3813 if (ret < 0) {
3814 btrfs_tree_unlock(right);
3815 free_extent_buffer(right);
3816 return ret;
3817 }
3818
3819 if (split == 2) {
3820 BUG_ON(num_doubles != 0);
3821 num_doubles++;
3822 goto again;
3823 }
3824
3825 return 0;
3826
3827push_for_double:
3828 push_for_double_split(trans, root, path, data_size);
3829 tried_avoid_double = 1;
3830 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3831 return 0;
3832 goto again;
3833}
3834
3835static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3836 struct btrfs_root *root,
3837 struct btrfs_path *path, int ins_len)
3838{
3839 struct btrfs_key key;
3840 struct extent_buffer *leaf;
3841 struct btrfs_file_extent_item *fi;
3842 u64 extent_len = 0;
3843 u32 item_size;
3844 int ret;
3845
3846 leaf = path->nodes[0];
3847 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3848
3849 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3850 key.type != BTRFS_EXTENT_CSUM_KEY);
3851
3852 if (btrfs_leaf_free_space(leaf) >= ins_len)
3853 return 0;
3854
3855 item_size = btrfs_item_size(leaf, path->slots[0]);
3856 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3857 fi = btrfs_item_ptr(leaf, path->slots[0],
3858 struct btrfs_file_extent_item);
3859 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3860 }
3861 btrfs_release_path(path);
3862
3863 path->keep_locks = 1;
3864 path->search_for_split = 1;
3865 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3866 path->search_for_split = 0;
3867 if (ret > 0)
3868 ret = -EAGAIN;
3869 if (ret < 0)
3870 goto err;
3871
3872 ret = -EAGAIN;
3873 leaf = path->nodes[0];
3874 /* if our item isn't there, return now */
3875 if (item_size != btrfs_item_size(leaf, path->slots[0]))
3876 goto err;
3877
3878 /* the leaf has changed, it now has room. return now */
3879 if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
3880 goto err;
3881
3882 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3883 fi = btrfs_item_ptr(leaf, path->slots[0],
3884 struct btrfs_file_extent_item);
3885 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3886 goto err;
3887 }
3888
3889 ret = split_leaf(trans, root, &key, path, ins_len, 1);
3890 if (ret)
3891 goto err;
3892
3893 path->keep_locks = 0;
3894 btrfs_unlock_up_safe(path, 1);
3895 return 0;
3896err:
3897 path->keep_locks = 0;
3898 return ret;
3899}
3900
3901static noinline int split_item(struct btrfs_trans_handle *trans,
3902 struct btrfs_path *path,
3903 const struct btrfs_key *new_key,
3904 unsigned long split_offset)
3905{
3906 struct extent_buffer *leaf;
3907 int orig_slot, slot;
3908 char *buf;
3909 u32 nritems;
3910 u32 item_size;
3911 u32 orig_offset;
3912 struct btrfs_disk_key disk_key;
3913
3914 leaf = path->nodes[0];
3915 /*
3916 * Shouldn't happen because the caller must have previously called
3917 * setup_leaf_for_split() to make room for the new item in the leaf.
3918 */
3919 if (WARN_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item)))
3920 return -ENOSPC;
3921
3922 orig_slot = path->slots[0];
3923 orig_offset = btrfs_item_offset(leaf, path->slots[0]);
3924 item_size = btrfs_item_size(leaf, path->slots[0]);
3925
3926 buf = kmalloc(item_size, GFP_NOFS);
3927 if (!buf)
3928 return -ENOMEM;
3929
3930 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3931 path->slots[0]), item_size);
3932
3933 slot = path->slots[0] + 1;
3934 nritems = btrfs_header_nritems(leaf);
3935 if (slot != nritems) {
3936 /* shift the items */
3937 memmove_leaf_items(leaf, slot + 1, slot, nritems - slot);
3938 }
3939
3940 btrfs_cpu_key_to_disk(&disk_key, new_key);
3941 btrfs_set_item_key(leaf, &disk_key, slot);
3942
3943 btrfs_set_item_offset(leaf, slot, orig_offset);
3944 btrfs_set_item_size(leaf, slot, item_size - split_offset);
3945
3946 btrfs_set_item_offset(leaf, orig_slot,
3947 orig_offset + item_size - split_offset);
3948 btrfs_set_item_size(leaf, orig_slot, split_offset);
3949
3950 btrfs_set_header_nritems(leaf, nritems + 1);
3951
3952 /* write the data for the start of the original item */
3953 write_extent_buffer(leaf, buf,
3954 btrfs_item_ptr_offset(leaf, path->slots[0]),
3955 split_offset);
3956
3957 /* write the data for the new item */
3958 write_extent_buffer(leaf, buf + split_offset,
3959 btrfs_item_ptr_offset(leaf, slot),
3960 item_size - split_offset);
3961 btrfs_mark_buffer_dirty(trans, leaf);
3962
3963 BUG_ON(btrfs_leaf_free_space(leaf) < 0);
3964 kfree(buf);
3965 return 0;
3966}
3967
3968/*
3969 * This function splits a single item into two items,
3970 * giving 'new_key' to the new item and splitting the
3971 * old one at split_offset (from the start of the item).
3972 *
3973 * The path may be released by this operation. After
3974 * the split, the path is pointing to the old item. The
3975 * new item is going to be in the same node as the old one.
3976 *
3977 * Note, the item being split must be smaller enough to live alone on
3978 * a tree block with room for one extra struct btrfs_item
3979 *
3980 * This allows us to split the item in place, keeping a lock on the
3981 * leaf the entire time.
3982 */
3983int btrfs_split_item(struct btrfs_trans_handle *trans,
3984 struct btrfs_root *root,
3985 struct btrfs_path *path,
3986 const struct btrfs_key *new_key,
3987 unsigned long split_offset)
3988{
3989 int ret;
3990 ret = setup_leaf_for_split(trans, root, path,
3991 sizeof(struct btrfs_item));
3992 if (ret)
3993 return ret;
3994
3995 ret = split_item(trans, path, new_key, split_offset);
3996 return ret;
3997}
3998
3999/*
4000 * make the item pointed to by the path smaller. new_size indicates
4001 * how small to make it, and from_end tells us if we just chop bytes
4002 * off the end of the item or if we shift the item to chop bytes off
4003 * the front.
4004 */
4005void btrfs_truncate_item(struct btrfs_trans_handle *trans,
4006 struct btrfs_path *path, u32 new_size, int from_end)
4007{
4008 int slot;
4009 struct extent_buffer *leaf;
4010 u32 nritems;
4011 unsigned int data_end;
4012 unsigned int old_data_start;
4013 unsigned int old_size;
4014 unsigned int size_diff;
4015 int i;
4016 struct btrfs_map_token token;
4017
4018 leaf = path->nodes[0];
4019 slot = path->slots[0];
4020
4021 old_size = btrfs_item_size(leaf, slot);
4022 if (old_size == new_size)
4023 return;
4024
4025 nritems = btrfs_header_nritems(leaf);
4026 data_end = leaf_data_end(leaf);
4027
4028 old_data_start = btrfs_item_offset(leaf, slot);
4029
4030 size_diff = old_size - new_size;
4031
4032 BUG_ON(slot < 0);
4033 BUG_ON(slot >= nritems);
4034
4035 /*
4036 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4037 */
4038 /* first correct the data pointers */
4039 btrfs_init_map_token(&token, leaf);
4040 for (i = slot; i < nritems; i++) {
4041 u32 ioff;
4042
4043 ioff = btrfs_token_item_offset(&token, i);
4044 btrfs_set_token_item_offset(&token, i, ioff + size_diff);
4045 }
4046
4047 /* shift the data */
4048 if (from_end) {
4049 memmove_leaf_data(leaf, data_end + size_diff, data_end,
4050 old_data_start + new_size - data_end);
4051 } else {
4052 struct btrfs_disk_key disk_key;
4053 u64 offset;
4054
4055 btrfs_item_key(leaf, &disk_key, slot);
4056
4057 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4058 unsigned long ptr;
4059 struct btrfs_file_extent_item *fi;
4060
4061 fi = btrfs_item_ptr(leaf, slot,
4062 struct btrfs_file_extent_item);
4063 fi = (struct btrfs_file_extent_item *)(
4064 (unsigned long)fi - size_diff);
4065
4066 if (btrfs_file_extent_type(leaf, fi) ==
4067 BTRFS_FILE_EXTENT_INLINE) {
4068 ptr = btrfs_item_ptr_offset(leaf, slot);
4069 memmove_extent_buffer(leaf, ptr,
4070 (unsigned long)fi,
4071 BTRFS_FILE_EXTENT_INLINE_DATA_START);
4072 }
4073 }
4074
4075 memmove_leaf_data(leaf, data_end + size_diff, data_end,
4076 old_data_start - data_end);
4077
4078 offset = btrfs_disk_key_offset(&disk_key);
4079 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4080 btrfs_set_item_key(leaf, &disk_key, slot);
4081 if (slot == 0)
4082 fixup_low_keys(trans, path, &disk_key, 1);
4083 }
4084
4085 btrfs_set_item_size(leaf, slot, new_size);
4086 btrfs_mark_buffer_dirty(trans, leaf);
4087
4088 if (btrfs_leaf_free_space(leaf) < 0) {
4089 btrfs_print_leaf(leaf);
4090 BUG();
4091 }
4092}
4093
4094/*
4095 * make the item pointed to by the path bigger, data_size is the added size.
4096 */
4097void btrfs_extend_item(struct btrfs_trans_handle *trans,
4098 struct btrfs_path *path, u32 data_size)
4099{
4100 int slot;
4101 struct extent_buffer *leaf;
4102 u32 nritems;
4103 unsigned int data_end;
4104 unsigned int old_data;
4105 unsigned int old_size;
4106 int i;
4107 struct btrfs_map_token token;
4108
4109 leaf = path->nodes[0];
4110
4111 nritems = btrfs_header_nritems(leaf);
4112 data_end = leaf_data_end(leaf);
4113
4114 if (btrfs_leaf_free_space(leaf) < data_size) {
4115 btrfs_print_leaf(leaf);
4116 BUG();
4117 }
4118 slot = path->slots[0];
4119 old_data = btrfs_item_data_end(leaf, slot);
4120
4121 BUG_ON(slot < 0);
4122 if (slot >= nritems) {
4123 btrfs_print_leaf(leaf);
4124 btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
4125 slot, nritems);
4126 BUG();
4127 }
4128
4129 /*
4130 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4131 */
4132 /* first correct the data pointers */
4133 btrfs_init_map_token(&token, leaf);
4134 for (i = slot; i < nritems; i++) {
4135 u32 ioff;
4136
4137 ioff = btrfs_token_item_offset(&token, i);
4138 btrfs_set_token_item_offset(&token, i, ioff - data_size);
4139 }
4140
4141 /* shift the data */
4142 memmove_leaf_data(leaf, data_end - data_size, data_end,
4143 old_data - data_end);
4144
4145 data_end = old_data;
4146 old_size = btrfs_item_size(leaf, slot);
4147 btrfs_set_item_size(leaf, slot, old_size + data_size);
4148 btrfs_mark_buffer_dirty(trans, leaf);
4149
4150 if (btrfs_leaf_free_space(leaf) < 0) {
4151 btrfs_print_leaf(leaf);
4152 BUG();
4153 }
4154}
4155
4156/*
4157 * Make space in the node before inserting one or more items.
4158 *
4159 * @trans: transaction handle
4160 * @root: root we are inserting items to
4161 * @path: points to the leaf/slot where we are going to insert new items
4162 * @batch: information about the batch of items to insert
4163 *
4164 * Main purpose is to save stack depth by doing the bulk of the work in a
4165 * function that doesn't call btrfs_search_slot
4166 */
4167static void setup_items_for_insert(struct btrfs_trans_handle *trans,
4168 struct btrfs_root *root, struct btrfs_path *path,
4169 const struct btrfs_item_batch *batch)
4170{
4171 struct btrfs_fs_info *fs_info = root->fs_info;
4172 int i;
4173 u32 nritems;
4174 unsigned int data_end;
4175 struct btrfs_disk_key disk_key;
4176 struct extent_buffer *leaf;
4177 int slot;
4178 struct btrfs_map_token token;
4179 u32 total_size;
4180
4181 /*
4182 * Before anything else, update keys in the parent and other ancestors
4183 * if needed, then release the write locks on them, so that other tasks
4184 * can use them while we modify the leaf.
4185 */
4186 if (path->slots[0] == 0) {
4187 btrfs_cpu_key_to_disk(&disk_key, &batch->keys[0]);
4188 fixup_low_keys(trans, path, &disk_key, 1);
4189 }
4190 btrfs_unlock_up_safe(path, 1);
4191
4192 leaf = path->nodes[0];
4193 slot = path->slots[0];
4194
4195 nritems = btrfs_header_nritems(leaf);
4196 data_end = leaf_data_end(leaf);
4197 total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
4198
4199 if (btrfs_leaf_free_space(leaf) < total_size) {
4200 btrfs_print_leaf(leaf);
4201 btrfs_crit(fs_info, "not enough freespace need %u have %d",
4202 total_size, btrfs_leaf_free_space(leaf));
4203 BUG();
4204 }
4205
4206 btrfs_init_map_token(&token, leaf);
4207 if (slot != nritems) {
4208 unsigned int old_data = btrfs_item_data_end(leaf, slot);
4209
4210 if (old_data < data_end) {
4211 btrfs_print_leaf(leaf);
4212 btrfs_crit(fs_info,
4213 "item at slot %d with data offset %u beyond data end of leaf %u",
4214 slot, old_data, data_end);
4215 BUG();
4216 }
4217 /*
4218 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4219 */
4220 /* first correct the data pointers */
4221 for (i = slot; i < nritems; i++) {
4222 u32 ioff;
4223
4224 ioff = btrfs_token_item_offset(&token, i);
4225 btrfs_set_token_item_offset(&token, i,
4226 ioff - batch->total_data_size);
4227 }
4228 /* shift the items */
4229 memmove_leaf_items(leaf, slot + batch->nr, slot, nritems - slot);
4230
4231 /* shift the data */
4232 memmove_leaf_data(leaf, data_end - batch->total_data_size,
4233 data_end, old_data - data_end);
4234 data_end = old_data;
4235 }
4236
4237 /* setup the item for the new data */
4238 for (i = 0; i < batch->nr; i++) {
4239 btrfs_cpu_key_to_disk(&disk_key, &batch->keys[i]);
4240 btrfs_set_item_key(leaf, &disk_key, slot + i);
4241 data_end -= batch->data_sizes[i];
4242 btrfs_set_token_item_offset(&token, slot + i, data_end);
4243 btrfs_set_token_item_size(&token, slot + i, batch->data_sizes[i]);
4244 }
4245
4246 btrfs_set_header_nritems(leaf, nritems + batch->nr);
4247 btrfs_mark_buffer_dirty(trans, leaf);
4248
4249 if (btrfs_leaf_free_space(leaf) < 0) {
4250 btrfs_print_leaf(leaf);
4251 BUG();
4252 }
4253}
4254
4255/*
4256 * Insert a new item into a leaf.
4257 *
4258 * @trans: Transaction handle.
4259 * @root: The root of the btree.
4260 * @path: A path pointing to the target leaf and slot.
4261 * @key: The key of the new item.
4262 * @data_size: The size of the data associated with the new key.
4263 */
4264void btrfs_setup_item_for_insert(struct btrfs_trans_handle *trans,
4265 struct btrfs_root *root,
4266 struct btrfs_path *path,
4267 const struct btrfs_key *key,
4268 u32 data_size)
4269{
4270 struct btrfs_item_batch batch;
4271
4272 batch.keys = key;
4273 batch.data_sizes = &data_size;
4274 batch.total_data_size = data_size;
4275 batch.nr = 1;
4276
4277 setup_items_for_insert(trans, root, path, &batch);
4278}
4279
4280/*
4281 * Given a key and some data, insert items into the tree.
4282 * This does all the path init required, making room in the tree if needed.
4283 */
4284int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4285 struct btrfs_root *root,
4286 struct btrfs_path *path,
4287 const struct btrfs_item_batch *batch)
4288{
4289 int ret = 0;
4290 int slot;
4291 u32 total_size;
4292
4293 total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
4294 ret = btrfs_search_slot(trans, root, &batch->keys[0], path, total_size, 1);
4295 if (ret == 0)
4296 return -EEXIST;
4297 if (ret < 0)
4298 return ret;
4299
4300 slot = path->slots[0];
4301 BUG_ON(slot < 0);
4302
4303 setup_items_for_insert(trans, root, path, batch);
4304 return 0;
4305}
4306
4307/*
4308 * Given a key and some data, insert an item into the tree.
4309 * This does all the path init required, making room in the tree if needed.
4310 */
4311int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4312 const struct btrfs_key *cpu_key, void *data,
4313 u32 data_size)
4314{
4315 int ret = 0;
4316 struct btrfs_path *path;
4317 struct extent_buffer *leaf;
4318 unsigned long ptr;
4319
4320 path = btrfs_alloc_path();
4321 if (!path)
4322 return -ENOMEM;
4323 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4324 if (!ret) {
4325 leaf = path->nodes[0];
4326 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4327 write_extent_buffer(leaf, data, ptr, data_size);
4328 btrfs_mark_buffer_dirty(trans, leaf);
4329 }
4330 btrfs_free_path(path);
4331 return ret;
4332}
4333
4334/*
4335 * This function duplicates an item, giving 'new_key' to the new item.
4336 * It guarantees both items live in the same tree leaf and the new item is
4337 * contiguous with the original item.
4338 *
4339 * This allows us to split a file extent in place, keeping a lock on the leaf
4340 * the entire time.
4341 */
4342int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4343 struct btrfs_root *root,
4344 struct btrfs_path *path,
4345 const struct btrfs_key *new_key)
4346{
4347 struct extent_buffer *leaf;
4348 int ret;
4349 u32 item_size;
4350
4351 leaf = path->nodes[0];
4352 item_size = btrfs_item_size(leaf, path->slots[0]);
4353 ret = setup_leaf_for_split(trans, root, path,
4354 item_size + sizeof(struct btrfs_item));
4355 if (ret)
4356 return ret;
4357
4358 path->slots[0]++;
4359 btrfs_setup_item_for_insert(trans, root, path, new_key, item_size);
4360 leaf = path->nodes[0];
4361 memcpy_extent_buffer(leaf,
4362 btrfs_item_ptr_offset(leaf, path->slots[0]),
4363 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4364 item_size);
4365 return 0;
4366}
4367
4368/*
4369 * delete the pointer from a given node.
4370 *
4371 * the tree should have been previously balanced so the deletion does not
4372 * empty a node.
4373 *
4374 * This is exported for use inside btrfs-progs, don't un-export it.
4375 */
4376int btrfs_del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4377 struct btrfs_path *path, int level, int slot)
4378{
4379 struct extent_buffer *parent = path->nodes[level];
4380 u32 nritems;
4381 int ret;
4382
4383 nritems = btrfs_header_nritems(parent);
4384 if (slot != nritems - 1) {
4385 if (level) {
4386 ret = btrfs_tree_mod_log_insert_move(parent, slot,
4387 slot + 1, nritems - slot - 1);
4388 if (ret < 0) {
4389 btrfs_abort_transaction(trans, ret);
4390 return ret;
4391 }
4392 }
4393 memmove_extent_buffer(parent,
4394 btrfs_node_key_ptr_offset(parent, slot),
4395 btrfs_node_key_ptr_offset(parent, slot + 1),
4396 sizeof(struct btrfs_key_ptr) *
4397 (nritems - slot - 1));
4398 } else if (level) {
4399 ret = btrfs_tree_mod_log_insert_key(parent, slot,
4400 BTRFS_MOD_LOG_KEY_REMOVE);
4401 if (ret < 0) {
4402 btrfs_abort_transaction(trans, ret);
4403 return ret;
4404 }
4405 }
4406
4407 nritems--;
4408 btrfs_set_header_nritems(parent, nritems);
4409 if (nritems == 0 && parent == root->node) {
4410 BUG_ON(btrfs_header_level(root->node) != 1);
4411 /* just turn the root into a leaf and break */
4412 btrfs_set_header_level(root->node, 0);
4413 } else if (slot == 0) {
4414 struct btrfs_disk_key disk_key;
4415
4416 btrfs_node_key(parent, &disk_key, 0);
4417 fixup_low_keys(trans, path, &disk_key, level + 1);
4418 }
4419 btrfs_mark_buffer_dirty(trans, parent);
4420 return 0;
4421}
4422
4423/*
4424 * a helper function to delete the leaf pointed to by path->slots[1] and
4425 * path->nodes[1].
4426 *
4427 * This deletes the pointer in path->nodes[1] and frees the leaf
4428 * block extent. zero is returned if it all worked out, < 0 otherwise.
4429 *
4430 * The path must have already been setup for deleting the leaf, including
4431 * all the proper balancing. path->nodes[1] must be locked.
4432 */
4433static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
4434 struct btrfs_root *root,
4435 struct btrfs_path *path,
4436 struct extent_buffer *leaf)
4437{
4438 int ret;
4439
4440 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4441 ret = btrfs_del_ptr(trans, root, path, 1, path->slots[1]);
4442 if (ret < 0)
4443 return ret;
4444
4445 /*
4446 * btrfs_free_extent is expensive, we want to make sure we
4447 * aren't holding any locks when we call it
4448 */
4449 btrfs_unlock_up_safe(path, 0);
4450
4451 root_sub_used_bytes(root);
4452
4453 atomic_inc(&leaf->refs);
4454 btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
4455 free_extent_buffer_stale(leaf);
4456 return 0;
4457}
4458/*
4459 * delete the item at the leaf level in path. If that empties
4460 * the leaf, remove it from the tree
4461 */
4462int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4463 struct btrfs_path *path, int slot, int nr)
4464{
4465 struct btrfs_fs_info *fs_info = root->fs_info;
4466 struct extent_buffer *leaf;
4467 int ret = 0;
4468 int wret;
4469 u32 nritems;
4470
4471 leaf = path->nodes[0];
4472 nritems = btrfs_header_nritems(leaf);
4473
4474 if (slot + nr != nritems) {
4475 const u32 last_off = btrfs_item_offset(leaf, slot + nr - 1);
4476 const int data_end = leaf_data_end(leaf);
4477 struct btrfs_map_token token;
4478 u32 dsize = 0;
4479 int i;
4480
4481 for (i = 0; i < nr; i++)
4482 dsize += btrfs_item_size(leaf, slot + i);
4483
4484 memmove_leaf_data(leaf, data_end + dsize, data_end,
4485 last_off - data_end);
4486
4487 btrfs_init_map_token(&token, leaf);
4488 for (i = slot + nr; i < nritems; i++) {
4489 u32 ioff;
4490
4491 ioff = btrfs_token_item_offset(&token, i);
4492 btrfs_set_token_item_offset(&token, i, ioff + dsize);
4493 }
4494
4495 memmove_leaf_items(leaf, slot, slot + nr, nritems - slot - nr);
4496 }
4497 btrfs_set_header_nritems(leaf, nritems - nr);
4498 nritems -= nr;
4499
4500 /* delete the leaf if we've emptied it */
4501 if (nritems == 0) {
4502 if (leaf == root->node) {
4503 btrfs_set_header_level(leaf, 0);
4504 } else {
4505 btrfs_clear_buffer_dirty(trans, leaf);
4506 ret = btrfs_del_leaf(trans, root, path, leaf);
4507 if (ret < 0)
4508 return ret;
4509 }
4510 } else {
4511 int used = leaf_space_used(leaf, 0, nritems);
4512 if (slot == 0) {
4513 struct btrfs_disk_key disk_key;
4514
4515 btrfs_item_key(leaf, &disk_key, 0);
4516 fixup_low_keys(trans, path, &disk_key, 1);
4517 }
4518
4519 /*
4520 * Try to delete the leaf if it is mostly empty. We do this by
4521 * trying to move all its items into its left and right neighbours.
4522 * If we can't move all the items, then we don't delete it - it's
4523 * not ideal, but future insertions might fill the leaf with more
4524 * items, or items from other leaves might be moved later into our
4525 * leaf due to deletions on those leaves.
4526 */
4527 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
4528 u32 min_push_space;
4529
4530 /* push_leaf_left fixes the path.
4531 * make sure the path still points to our leaf
4532 * for possible call to btrfs_del_ptr below
4533 */
4534 slot = path->slots[1];
4535 atomic_inc(&leaf->refs);
4536 /*
4537 * We want to be able to at least push one item to the
4538 * left neighbour leaf, and that's the first item.
4539 */
4540 min_push_space = sizeof(struct btrfs_item) +
4541 btrfs_item_size(leaf, 0);
4542 wret = push_leaf_left(trans, root, path, 0,
4543 min_push_space, 1, (u32)-1);
4544 if (wret < 0 && wret != -ENOSPC)
4545 ret = wret;
4546
4547 if (path->nodes[0] == leaf &&
4548 btrfs_header_nritems(leaf)) {
4549 /*
4550 * If we were not able to push all items from our
4551 * leaf to its left neighbour, then attempt to
4552 * either push all the remaining items to the
4553 * right neighbour or none. There's no advantage
4554 * in pushing only some items, instead of all, as
4555 * it's pointless to end up with a leaf having
4556 * too few items while the neighbours can be full
4557 * or nearly full.
4558 */
4559 nritems = btrfs_header_nritems(leaf);
4560 min_push_space = leaf_space_used(leaf, 0, nritems);
4561 wret = push_leaf_right(trans, root, path, 0,
4562 min_push_space, 1, 0);
4563 if (wret < 0 && wret != -ENOSPC)
4564 ret = wret;
4565 }
4566
4567 if (btrfs_header_nritems(leaf) == 0) {
4568 path->slots[1] = slot;
4569 ret = btrfs_del_leaf(trans, root, path, leaf);
4570 if (ret < 0)
4571 return ret;
4572 free_extent_buffer(leaf);
4573 ret = 0;
4574 } else {
4575 /* if we're still in the path, make sure
4576 * we're dirty. Otherwise, one of the
4577 * push_leaf functions must have already
4578 * dirtied this buffer
4579 */
4580 if (path->nodes[0] == leaf)
4581 btrfs_mark_buffer_dirty(trans, leaf);
4582 free_extent_buffer(leaf);
4583 }
4584 } else {
4585 btrfs_mark_buffer_dirty(trans, leaf);
4586 }
4587 }
4588 return ret;
4589}
4590
4591/*
4592 * A helper function to walk down the tree starting at min_key, and looking
4593 * for nodes or leaves that are have a minimum transaction id.
4594 * This is used by the btree defrag code, and tree logging
4595 *
4596 * This does not cow, but it does stuff the starting key it finds back
4597 * into min_key, so you can call btrfs_search_slot with cow=1 on the
4598 * key and get a writable path.
4599 *
4600 * This honors path->lowest_level to prevent descent past a given level
4601 * of the tree.
4602 *
4603 * min_trans indicates the oldest transaction that you are interested
4604 * in walking through. Any nodes or leaves older than min_trans are
4605 * skipped over (without reading them).
4606 *
4607 * returns zero if something useful was found, < 0 on error and 1 if there
4608 * was nothing in the tree that matched the search criteria.
4609 */
4610int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4611 struct btrfs_path *path,
4612 u64 min_trans)
4613{
4614 struct extent_buffer *cur;
4615 struct btrfs_key found_key;
4616 int slot;
4617 int sret;
4618 u32 nritems;
4619 int level;
4620 int ret = 1;
4621 int keep_locks = path->keep_locks;
4622
4623 ASSERT(!path->nowait);
4624 path->keep_locks = 1;
4625again:
4626 cur = btrfs_read_lock_root_node(root);
4627 level = btrfs_header_level(cur);
4628 WARN_ON(path->nodes[level]);
4629 path->nodes[level] = cur;
4630 path->locks[level] = BTRFS_READ_LOCK;
4631
4632 if (btrfs_header_generation(cur) < min_trans) {
4633 ret = 1;
4634 goto out;
4635 }
4636 while (1) {
4637 nritems = btrfs_header_nritems(cur);
4638 level = btrfs_header_level(cur);
4639 sret = btrfs_bin_search(cur, 0, min_key, &slot);
4640 if (sret < 0) {
4641 ret = sret;
4642 goto out;
4643 }
4644
4645 /* at the lowest level, we're done, setup the path and exit */
4646 if (level == path->lowest_level) {
4647 if (slot >= nritems)
4648 goto find_next_key;
4649 ret = 0;
4650 path->slots[level] = slot;
4651 btrfs_item_key_to_cpu(cur, &found_key, slot);
4652 goto out;
4653 }
4654 if (sret && slot > 0)
4655 slot--;
4656 /*
4657 * check this node pointer against the min_trans parameters.
4658 * If it is too old, skip to the next one.
4659 */
4660 while (slot < nritems) {
4661 u64 gen;
4662
4663 gen = btrfs_node_ptr_generation(cur, slot);
4664 if (gen < min_trans) {
4665 slot++;
4666 continue;
4667 }
4668 break;
4669 }
4670find_next_key:
4671 /*
4672 * we didn't find a candidate key in this node, walk forward
4673 * and find another one
4674 */
4675 if (slot >= nritems) {
4676 path->slots[level] = slot;
4677 sret = btrfs_find_next_key(root, path, min_key, level,
4678 min_trans);
4679 if (sret == 0) {
4680 btrfs_release_path(path);
4681 goto again;
4682 } else {
4683 goto out;
4684 }
4685 }
4686 /* save our key for returning back */
4687 btrfs_node_key_to_cpu(cur, &found_key, slot);
4688 path->slots[level] = slot;
4689 if (level == path->lowest_level) {
4690 ret = 0;
4691 goto out;
4692 }
4693 cur = btrfs_read_node_slot(cur, slot);
4694 if (IS_ERR(cur)) {
4695 ret = PTR_ERR(cur);
4696 goto out;
4697 }
4698
4699 btrfs_tree_read_lock(cur);
4700
4701 path->locks[level - 1] = BTRFS_READ_LOCK;
4702 path->nodes[level - 1] = cur;
4703 unlock_up(path, level, 1, 0, NULL);
4704 }
4705out:
4706 path->keep_locks = keep_locks;
4707 if (ret == 0) {
4708 btrfs_unlock_up_safe(path, path->lowest_level + 1);
4709 memcpy(min_key, &found_key, sizeof(found_key));
4710 }
4711 return ret;
4712}
4713
4714/*
4715 * this is similar to btrfs_next_leaf, but does not try to preserve
4716 * and fixup the path. It looks for and returns the next key in the
4717 * tree based on the current path and the min_trans parameters.
4718 *
4719 * 0 is returned if another key is found, < 0 if there are any errors
4720 * and 1 is returned if there are no higher keys in the tree
4721 *
4722 * path->keep_locks should be set to 1 on the search made before
4723 * calling this function.
4724 */
4725int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4726 struct btrfs_key *key, int level, u64 min_trans)
4727{
4728 int slot;
4729 struct extent_buffer *c;
4730
4731 WARN_ON(!path->keep_locks && !path->skip_locking);
4732 while (level < BTRFS_MAX_LEVEL) {
4733 if (!path->nodes[level])
4734 return 1;
4735
4736 slot = path->slots[level] + 1;
4737 c = path->nodes[level];
4738next:
4739 if (slot >= btrfs_header_nritems(c)) {
4740 int ret;
4741 int orig_lowest;
4742 struct btrfs_key cur_key;
4743 if (level + 1 >= BTRFS_MAX_LEVEL ||
4744 !path->nodes[level + 1])
4745 return 1;
4746
4747 if (path->locks[level + 1] || path->skip_locking) {
4748 level++;
4749 continue;
4750 }
4751
4752 slot = btrfs_header_nritems(c) - 1;
4753 if (level == 0)
4754 btrfs_item_key_to_cpu(c, &cur_key, slot);
4755 else
4756 btrfs_node_key_to_cpu(c, &cur_key, slot);
4757
4758 orig_lowest = path->lowest_level;
4759 btrfs_release_path(path);
4760 path->lowest_level = level;
4761 ret = btrfs_search_slot(NULL, root, &cur_key, path,
4762 0, 0);
4763 path->lowest_level = orig_lowest;
4764 if (ret < 0)
4765 return ret;
4766
4767 c = path->nodes[level];
4768 slot = path->slots[level];
4769 if (ret == 0)
4770 slot++;
4771 goto next;
4772 }
4773
4774 if (level == 0)
4775 btrfs_item_key_to_cpu(c, key, slot);
4776 else {
4777 u64 gen = btrfs_node_ptr_generation(c, slot);
4778
4779 if (gen < min_trans) {
4780 slot++;
4781 goto next;
4782 }
4783 btrfs_node_key_to_cpu(c, key, slot);
4784 }
4785 return 0;
4786 }
4787 return 1;
4788}
4789
4790int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
4791 u64 time_seq)
4792{
4793 int slot;
4794 int level;
4795 struct extent_buffer *c;
4796 struct extent_buffer *next;
4797 struct btrfs_fs_info *fs_info = root->fs_info;
4798 struct btrfs_key key;
4799 bool need_commit_sem = false;
4800 u32 nritems;
4801 int ret;
4802 int i;
4803
4804 /*
4805 * The nowait semantics are used only for write paths, where we don't
4806 * use the tree mod log and sequence numbers.
4807 */
4808 if (time_seq)
4809 ASSERT(!path->nowait);
4810
4811 nritems = btrfs_header_nritems(path->nodes[0]);
4812 if (nritems == 0)
4813 return 1;
4814
4815 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
4816again:
4817 level = 1;
4818 next = NULL;
4819 btrfs_release_path(path);
4820
4821 path->keep_locks = 1;
4822
4823 if (time_seq) {
4824 ret = btrfs_search_old_slot(root, &key, path, time_seq);
4825 } else {
4826 if (path->need_commit_sem) {
4827 path->need_commit_sem = 0;
4828 need_commit_sem = true;
4829 if (path->nowait) {
4830 if (!down_read_trylock(&fs_info->commit_root_sem)) {
4831 ret = -EAGAIN;
4832 goto done;
4833 }
4834 } else {
4835 down_read(&fs_info->commit_root_sem);
4836 }
4837 }
4838 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4839 }
4840 path->keep_locks = 0;
4841
4842 if (ret < 0)
4843 goto done;
4844
4845 nritems = btrfs_header_nritems(path->nodes[0]);
4846 /*
4847 * by releasing the path above we dropped all our locks. A balance
4848 * could have added more items next to the key that used to be
4849 * at the very end of the block. So, check again here and
4850 * advance the path if there are now more items available.
4851 */
4852 if (nritems > 0 && path->slots[0] < nritems - 1) {
4853 if (ret == 0)
4854 path->slots[0]++;
4855 ret = 0;
4856 goto done;
4857 }
4858 /*
4859 * So the above check misses one case:
4860 * - after releasing the path above, someone has removed the item that
4861 * used to be at the very end of the block, and balance between leafs
4862 * gets another one with bigger key.offset to replace it.
4863 *
4864 * This one should be returned as well, or we can get leaf corruption
4865 * later(esp. in __btrfs_drop_extents()).
4866 *
4867 * And a bit more explanation about this check,
4868 * with ret > 0, the key isn't found, the path points to the slot
4869 * where it should be inserted, so the path->slots[0] item must be the
4870 * bigger one.
4871 */
4872 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
4873 ret = 0;
4874 goto done;
4875 }
4876
4877 while (level < BTRFS_MAX_LEVEL) {
4878 if (!path->nodes[level]) {
4879 ret = 1;
4880 goto done;
4881 }
4882
4883 slot = path->slots[level] + 1;
4884 c = path->nodes[level];
4885 if (slot >= btrfs_header_nritems(c)) {
4886 level++;
4887 if (level == BTRFS_MAX_LEVEL) {
4888 ret = 1;
4889 goto done;
4890 }
4891 continue;
4892 }
4893
4894
4895 /*
4896 * Our current level is where we're going to start from, and to
4897 * make sure lockdep doesn't complain we need to drop our locks
4898 * and nodes from 0 to our current level.
4899 */
4900 for (i = 0; i < level; i++) {
4901 if (path->locks[level]) {
4902 btrfs_tree_read_unlock(path->nodes[i]);
4903 path->locks[i] = 0;
4904 }
4905 free_extent_buffer(path->nodes[i]);
4906 path->nodes[i] = NULL;
4907 }
4908
4909 next = c;
4910 ret = read_block_for_search(root, path, &next, level,
4911 slot, &key);
4912 if (ret == -EAGAIN && !path->nowait)
4913 goto again;
4914
4915 if (ret < 0) {
4916 btrfs_release_path(path);
4917 goto done;
4918 }
4919
4920 if (!path->skip_locking) {
4921 ret = btrfs_try_tree_read_lock(next);
4922 if (!ret && path->nowait) {
4923 ret = -EAGAIN;
4924 goto done;
4925 }
4926 if (!ret && time_seq) {
4927 /*
4928 * If we don't get the lock, we may be racing
4929 * with push_leaf_left, holding that lock while
4930 * itself waiting for the leaf we've currently
4931 * locked. To solve this situation, we give up
4932 * on our lock and cycle.
4933 */
4934 free_extent_buffer(next);
4935 btrfs_release_path(path);
4936 cond_resched();
4937 goto again;
4938 }
4939 if (!ret)
4940 btrfs_tree_read_lock(next);
4941 }
4942 break;
4943 }
4944 path->slots[level] = slot;
4945 while (1) {
4946 level--;
4947 path->nodes[level] = next;
4948 path->slots[level] = 0;
4949 if (!path->skip_locking)
4950 path->locks[level] = BTRFS_READ_LOCK;
4951 if (!level)
4952 break;
4953
4954 ret = read_block_for_search(root, path, &next, level,
4955 0, &key);
4956 if (ret == -EAGAIN && !path->nowait)
4957 goto again;
4958
4959 if (ret < 0) {
4960 btrfs_release_path(path);
4961 goto done;
4962 }
4963
4964 if (!path->skip_locking) {
4965 if (path->nowait) {
4966 if (!btrfs_try_tree_read_lock(next)) {
4967 ret = -EAGAIN;
4968 goto done;
4969 }
4970 } else {
4971 btrfs_tree_read_lock(next);
4972 }
4973 }
4974 }
4975 ret = 0;
4976done:
4977 unlock_up(path, 0, 1, 0, NULL);
4978 if (need_commit_sem) {
4979 int ret2;
4980
4981 path->need_commit_sem = 1;
4982 ret2 = finish_need_commit_sem_search(path);
4983 up_read(&fs_info->commit_root_sem);
4984 if (ret2)
4985 ret = ret2;
4986 }
4987
4988 return ret;
4989}
4990
4991int btrfs_next_old_item(struct btrfs_root *root, struct btrfs_path *path, u64 time_seq)
4992{
4993 path->slots[0]++;
4994 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
4995 return btrfs_next_old_leaf(root, path, time_seq);
4996 return 0;
4997}
4998
4999/*
5000 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5001 * searching until it gets past min_objectid or finds an item of 'type'
5002 *
5003 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5004 */
5005int btrfs_previous_item(struct btrfs_root *root,
5006 struct btrfs_path *path, u64 min_objectid,
5007 int type)
5008{
5009 struct btrfs_key found_key;
5010 struct extent_buffer *leaf;
5011 u32 nritems;
5012 int ret;
5013
5014 while (1) {
5015 if (path->slots[0] == 0) {
5016 ret = btrfs_prev_leaf(root, path);
5017 if (ret != 0)
5018 return ret;
5019 } else {
5020 path->slots[0]--;
5021 }
5022 leaf = path->nodes[0];
5023 nritems = btrfs_header_nritems(leaf);
5024 if (nritems == 0)
5025 return 1;
5026 if (path->slots[0] == nritems)
5027 path->slots[0]--;
5028
5029 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5030 if (found_key.objectid < min_objectid)
5031 break;
5032 if (found_key.type == type)
5033 return 0;
5034 if (found_key.objectid == min_objectid &&
5035 found_key.type < type)
5036 break;
5037 }
5038 return 1;
5039}
5040
5041/*
5042 * search in extent tree to find a previous Metadata/Data extent item with
5043 * min objecitd.
5044 *
5045 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5046 */
5047int btrfs_previous_extent_item(struct btrfs_root *root,
5048 struct btrfs_path *path, u64 min_objectid)
5049{
5050 struct btrfs_key found_key;
5051 struct extent_buffer *leaf;
5052 u32 nritems;
5053 int ret;
5054
5055 while (1) {
5056 if (path->slots[0] == 0) {
5057 ret = btrfs_prev_leaf(root, path);
5058 if (ret != 0)
5059 return ret;
5060 } else {
5061 path->slots[0]--;
5062 }
5063 leaf = path->nodes[0];
5064 nritems = btrfs_header_nritems(leaf);
5065 if (nritems == 0)
5066 return 1;
5067 if (path->slots[0] == nritems)
5068 path->slots[0]--;
5069
5070 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5071 if (found_key.objectid < min_objectid)
5072 break;
5073 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5074 found_key.type == BTRFS_METADATA_ITEM_KEY)
5075 return 0;
5076 if (found_key.objectid == min_objectid &&
5077 found_key.type < BTRFS_EXTENT_ITEM_KEY)
5078 break;
5079 }
5080 return 1;
5081}
5082
5083int __init btrfs_ctree_init(void)
5084{
5085 btrfs_path_cachep = kmem_cache_create("btrfs_path",
5086 sizeof(struct btrfs_path), 0,
5087 SLAB_MEM_SPREAD, NULL);
5088 if (!btrfs_path_cachep)
5089 return -ENOMEM;
5090 return 0;
5091}
5092
5093void __cold btrfs_ctree_exit(void)
5094{
5095 kmem_cache_destroy(btrfs_path_cachep);
5096}
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}