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