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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);
40static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
41 int level, int slot);
42
43static const struct btrfs_csums {
44 u16 size;
45 const char name[10];
46 const char driver[12];
47} btrfs_csums[] = {
48 [BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
49 [BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
50 [BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
51 [BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
52 .driver = "blake2b-256" },
53};
54
55/*
56 * The leaf data grows from end-to-front in the node. this returns the address
57 * of the start of the last item, which is the stop of the leaf data stack.
58 */
59static unsigned int leaf_data_end(const struct extent_buffer *leaf)
60{
61 u32 nr = btrfs_header_nritems(leaf);
62
63 if (nr == 0)
64 return BTRFS_LEAF_DATA_SIZE(leaf->fs_info);
65 return btrfs_item_offset(leaf, nr - 1);
66}
67
68/*
69 * Move data in a @leaf (using memmove, safe for overlapping ranges).
70 *
71 * @leaf: leaf that we're doing a memmove on
72 * @dst_offset: item data offset we're moving to
73 * @src_offset: item data offset were' moving from
74 * @len: length of the data we're moving
75 *
76 * Wrapper around memmove_extent_buffer() that takes into account the header on
77 * the leaf. The btrfs_item offset's start directly after the header, so we
78 * have to adjust any offsets to account for the header in the leaf. This
79 * handles that math to simplify the callers.
80 */
81static inline void memmove_leaf_data(const struct extent_buffer *leaf,
82 unsigned long dst_offset,
83 unsigned long src_offset,
84 unsigned long len)
85{
86 memmove_extent_buffer(leaf, btrfs_item_nr_offset(leaf, 0) + dst_offset,
87 btrfs_item_nr_offset(leaf, 0) + src_offset, len);
88}
89
90/*
91 * Copy item data from @src into @dst at the given @offset.
92 *
93 * @dst: destination leaf that we're copying into
94 * @src: source leaf that we're copying from
95 * @dst_offset: item data offset we're copying to
96 * @src_offset: item data offset were' copying from
97 * @len: length of the data we're copying
98 *
99 * Wrapper around copy_extent_buffer() that takes into account the header on
100 * the leaf. The btrfs_item offset's start directly after the header, so we
101 * have to adjust any offsets to account for the header in the leaf. This
102 * handles that math to simplify the callers.
103 */
104static inline void copy_leaf_data(const struct extent_buffer *dst,
105 const struct extent_buffer *src,
106 unsigned long dst_offset,
107 unsigned long src_offset, unsigned long len)
108{
109 copy_extent_buffer(dst, src, btrfs_item_nr_offset(dst, 0) + dst_offset,
110 btrfs_item_nr_offset(src, 0) + src_offset, len);
111}
112
113/*
114 * Move items in a @leaf (using memmove).
115 *
116 * @dst: destination leaf for the items
117 * @dst_item: the item nr we're copying into
118 * @src_item: the item nr we're copying from
119 * @nr_items: the number of items to copy
120 *
121 * Wrapper around memmove_extent_buffer() that does the math to get the
122 * appropriate offsets into the leaf from the item numbers.
123 */
124static inline void memmove_leaf_items(const struct extent_buffer *leaf,
125 int dst_item, int src_item, int nr_items)
126{
127 memmove_extent_buffer(leaf, btrfs_item_nr_offset(leaf, dst_item),
128 btrfs_item_nr_offset(leaf, src_item),
129 nr_items * sizeof(struct btrfs_item));
130}
131
132/*
133 * Copy items from @src into @dst at the given @offset.
134 *
135 * @dst: destination leaf for the items
136 * @src: source leaf for the items
137 * @dst_item: the item nr we're copying into
138 * @src_item: the item nr we're copying from
139 * @nr_items: the number of items to copy
140 *
141 * Wrapper around copy_extent_buffer() that does the math to get the
142 * appropriate offsets into the leaf from the item numbers.
143 */
144static inline void copy_leaf_items(const struct extent_buffer *dst,
145 const struct extent_buffer *src,
146 int dst_item, int src_item, int nr_items)
147{
148 copy_extent_buffer(dst, src, btrfs_item_nr_offset(dst, dst_item),
149 btrfs_item_nr_offset(src, src_item),
150 nr_items * sizeof(struct btrfs_item));
151}
152
153int btrfs_super_csum_size(const struct btrfs_super_block *s)
154{
155 u16 t = btrfs_super_csum_type(s);
156 /*
157 * csum type is validated at mount time
158 */
159 return btrfs_csums[t].size;
160}
161
162const char *btrfs_super_csum_name(u16 csum_type)
163{
164 /* csum type is validated at mount time */
165 return btrfs_csums[csum_type].name;
166}
167
168/*
169 * Return driver name if defined, otherwise the name that's also a valid driver
170 * name
171 */
172const char *btrfs_super_csum_driver(u16 csum_type)
173{
174 /* csum type is validated at mount time */
175 return btrfs_csums[csum_type].driver[0] ?
176 btrfs_csums[csum_type].driver :
177 btrfs_csums[csum_type].name;
178}
179
180size_t __attribute_const__ btrfs_get_num_csums(void)
181{
182 return ARRAY_SIZE(btrfs_csums);
183}
184
185struct btrfs_path *btrfs_alloc_path(void)
186{
187 might_sleep();
188
189 return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
190}
191
192/* this also releases the path */
193void btrfs_free_path(struct btrfs_path *p)
194{
195 if (!p)
196 return;
197 btrfs_release_path(p);
198 kmem_cache_free(btrfs_path_cachep, p);
199}
200
201/*
202 * path release drops references on the extent buffers in the path
203 * and it drops any locks held by this path
204 *
205 * It is safe to call this on paths that no locks or extent buffers held.
206 */
207noinline void btrfs_release_path(struct btrfs_path *p)
208{
209 int i;
210
211 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
212 p->slots[i] = 0;
213 if (!p->nodes[i])
214 continue;
215 if (p->locks[i]) {
216 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
217 p->locks[i] = 0;
218 }
219 free_extent_buffer(p->nodes[i]);
220 p->nodes[i] = NULL;
221 }
222}
223
224/*
225 * We want the transaction abort to print stack trace only for errors where the
226 * cause could be a bug, eg. due to ENOSPC, and not for common errors that are
227 * caused by external factors.
228 */
229bool __cold abort_should_print_stack(int errno)
230{
231 switch (errno) {
232 case -EIO:
233 case -EROFS:
234 case -ENOMEM:
235 return false;
236 }
237 return true;
238}
239
240/*
241 * safely gets a reference on the root node of a tree. A lock
242 * is not taken, so a concurrent writer may put a different node
243 * at the root of the tree. See btrfs_lock_root_node for the
244 * looping required.
245 *
246 * The extent buffer returned by this has a reference taken, so
247 * it won't disappear. It may stop being the root of the tree
248 * at any time because there are no locks held.
249 */
250struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
251{
252 struct extent_buffer *eb;
253
254 while (1) {
255 rcu_read_lock();
256 eb = rcu_dereference(root->node);
257
258 /*
259 * RCU really hurts here, we could free up the root node because
260 * it was COWed but we may not get the new root node yet so do
261 * the inc_not_zero dance and if it doesn't work then
262 * synchronize_rcu and try again.
263 */
264 if (atomic_inc_not_zero(&eb->refs)) {
265 rcu_read_unlock();
266 break;
267 }
268 rcu_read_unlock();
269 synchronize_rcu();
270 }
271 return eb;
272}
273
274/*
275 * Cowonly root (not-shareable trees, everything not subvolume or reloc roots),
276 * just get put onto a simple dirty list. Transaction walks this list to make
277 * sure they get properly updated on disk.
278 */
279static void add_root_to_dirty_list(struct btrfs_root *root)
280{
281 struct btrfs_fs_info *fs_info = root->fs_info;
282
283 if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
284 !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
285 return;
286
287 spin_lock(&fs_info->trans_lock);
288 if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
289 /* Want the extent tree to be the last on the list */
290 if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID)
291 list_move_tail(&root->dirty_list,
292 &fs_info->dirty_cowonly_roots);
293 else
294 list_move(&root->dirty_list,
295 &fs_info->dirty_cowonly_roots);
296 }
297 spin_unlock(&fs_info->trans_lock);
298}
299
300/*
301 * used by snapshot creation to make a copy of a root for a tree with
302 * a given objectid. The buffer with the new root node is returned in
303 * cow_ret, and this func returns zero on success or a negative error code.
304 */
305int btrfs_copy_root(struct btrfs_trans_handle *trans,
306 struct btrfs_root *root,
307 struct extent_buffer *buf,
308 struct extent_buffer **cow_ret, u64 new_root_objectid)
309{
310 struct btrfs_fs_info *fs_info = root->fs_info;
311 struct extent_buffer *cow;
312 int ret = 0;
313 int level;
314 struct btrfs_disk_key disk_key;
315
316 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
317 trans->transid != fs_info->running_transaction->transid);
318 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
319 trans->transid != root->last_trans);
320
321 level = btrfs_header_level(buf);
322 if (level == 0)
323 btrfs_item_key(buf, &disk_key, 0);
324 else
325 btrfs_node_key(buf, &disk_key, 0);
326
327 cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
328 &disk_key, level, buf->start, 0,
329 BTRFS_NESTING_NEW_ROOT);
330 if (IS_ERR(cow))
331 return PTR_ERR(cow);
332
333 copy_extent_buffer_full(cow, buf);
334 btrfs_set_header_bytenr(cow, cow->start);
335 btrfs_set_header_generation(cow, trans->transid);
336 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
337 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
338 BTRFS_HEADER_FLAG_RELOC);
339 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
340 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
341 else
342 btrfs_set_header_owner(cow, new_root_objectid);
343
344 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
345
346 WARN_ON(btrfs_header_generation(buf) > trans->transid);
347 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
348 ret = btrfs_inc_ref(trans, root, cow, 1);
349 else
350 ret = btrfs_inc_ref(trans, root, cow, 0);
351 if (ret) {
352 btrfs_tree_unlock(cow);
353 free_extent_buffer(cow);
354 btrfs_abort_transaction(trans, ret);
355 return ret;
356 }
357
358 btrfs_mark_buffer_dirty(cow);
359 *cow_ret = cow;
360 return 0;
361}
362
363/*
364 * check if the tree block can be shared by multiple trees
365 */
366int btrfs_block_can_be_shared(struct btrfs_root *root,
367 struct extent_buffer *buf)
368{
369 /*
370 * Tree blocks not in shareable trees and tree roots are never shared.
371 * If a block was allocated after the last snapshot and the block was
372 * not allocated by tree relocation, we know the block is not shared.
373 */
374 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
375 buf != root->node && buf != root->commit_root &&
376 (btrfs_header_generation(buf) <=
377 btrfs_root_last_snapshot(&root->root_item) ||
378 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
379 return 1;
380
381 return 0;
382}
383
384static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
385 struct btrfs_root *root,
386 struct extent_buffer *buf,
387 struct extent_buffer *cow,
388 int *last_ref)
389{
390 struct btrfs_fs_info *fs_info = root->fs_info;
391 u64 refs;
392 u64 owner;
393 u64 flags;
394 u64 new_flags = 0;
395 int ret;
396
397 /*
398 * Backrefs update rules:
399 *
400 * Always use full backrefs for extent pointers in tree block
401 * allocated by tree relocation.
402 *
403 * If a shared tree block is no longer referenced by its owner
404 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
405 * use full backrefs for extent pointers in tree block.
406 *
407 * If a tree block is been relocating
408 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
409 * use full backrefs for extent pointers in tree block.
410 * The reason for this is some operations (such as drop tree)
411 * are only allowed for blocks use full backrefs.
412 */
413
414 if (btrfs_block_can_be_shared(root, buf)) {
415 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
416 btrfs_header_level(buf), 1,
417 &refs, &flags);
418 if (ret)
419 return ret;
420 if (refs == 0) {
421 ret = -EROFS;
422 btrfs_handle_fs_error(fs_info, ret, NULL);
423 return ret;
424 }
425 } else {
426 refs = 1;
427 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
428 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
429 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
430 else
431 flags = 0;
432 }
433
434 owner = btrfs_header_owner(buf);
435 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
436 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
437
438 if (refs > 1) {
439 if ((owner == root->root_key.objectid ||
440 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
441 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
442 ret = btrfs_inc_ref(trans, root, buf, 1);
443 if (ret)
444 return ret;
445
446 if (root->root_key.objectid ==
447 BTRFS_TREE_RELOC_OBJECTID) {
448 ret = btrfs_dec_ref(trans, root, buf, 0);
449 if (ret)
450 return ret;
451 ret = btrfs_inc_ref(trans, root, cow, 1);
452 if (ret)
453 return ret;
454 }
455 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
456 } else {
457
458 if (root->root_key.objectid ==
459 BTRFS_TREE_RELOC_OBJECTID)
460 ret = btrfs_inc_ref(trans, root, cow, 1);
461 else
462 ret = btrfs_inc_ref(trans, root, cow, 0);
463 if (ret)
464 return ret;
465 }
466 if (new_flags != 0) {
467 int level = btrfs_header_level(buf);
468
469 ret = btrfs_set_disk_extent_flags(trans, buf,
470 new_flags, level);
471 if (ret)
472 return ret;
473 }
474 } else {
475 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
476 if (root->root_key.objectid ==
477 BTRFS_TREE_RELOC_OBJECTID)
478 ret = btrfs_inc_ref(trans, root, cow, 1);
479 else
480 ret = btrfs_inc_ref(trans, root, cow, 0);
481 if (ret)
482 return ret;
483 ret = btrfs_dec_ref(trans, root, buf, 1);
484 if (ret)
485 return ret;
486 }
487 btrfs_clean_tree_block(buf);
488 *last_ref = 1;
489 }
490 return 0;
491}
492
493/*
494 * does the dirty work in cow of a single block. The parent block (if
495 * supplied) is updated to point to the new cow copy. The new buffer is marked
496 * dirty and returned locked. If you modify the block it needs to be marked
497 * dirty again.
498 *
499 * search_start -- an allocation hint for the new block
500 *
501 * empty_size -- a hint that you plan on doing more cow. This is the size in
502 * bytes the allocator should try to find free next to the block it returns.
503 * This is just a hint and may be ignored by the allocator.
504 */
505static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
506 struct btrfs_root *root,
507 struct extent_buffer *buf,
508 struct extent_buffer *parent, int parent_slot,
509 struct extent_buffer **cow_ret,
510 u64 search_start, u64 empty_size,
511 enum btrfs_lock_nesting nest)
512{
513 struct btrfs_fs_info *fs_info = root->fs_info;
514 struct btrfs_disk_key disk_key;
515 struct extent_buffer *cow;
516 int level, ret;
517 int last_ref = 0;
518 int unlock_orig = 0;
519 u64 parent_start = 0;
520
521 if (*cow_ret == buf)
522 unlock_orig = 1;
523
524 btrfs_assert_tree_write_locked(buf);
525
526 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
527 trans->transid != fs_info->running_transaction->transid);
528 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
529 trans->transid != root->last_trans);
530
531 level = btrfs_header_level(buf);
532
533 if (level == 0)
534 btrfs_item_key(buf, &disk_key, 0);
535 else
536 btrfs_node_key(buf, &disk_key, 0);
537
538 if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
539 parent_start = parent->start;
540
541 cow = btrfs_alloc_tree_block(trans, root, parent_start,
542 root->root_key.objectid, &disk_key, level,
543 search_start, empty_size, nest);
544 if (IS_ERR(cow))
545 return PTR_ERR(cow);
546
547 /* cow is set to blocking by btrfs_init_new_buffer */
548
549 copy_extent_buffer_full(cow, buf);
550 btrfs_set_header_bytenr(cow, cow->start);
551 btrfs_set_header_generation(cow, trans->transid);
552 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
553 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
554 BTRFS_HEADER_FLAG_RELOC);
555 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
556 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
557 else
558 btrfs_set_header_owner(cow, root->root_key.objectid);
559
560 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
561
562 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
563 if (ret) {
564 btrfs_tree_unlock(cow);
565 free_extent_buffer(cow);
566 btrfs_abort_transaction(trans, ret);
567 return ret;
568 }
569
570 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
571 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
572 if (ret) {
573 btrfs_tree_unlock(cow);
574 free_extent_buffer(cow);
575 btrfs_abort_transaction(trans, ret);
576 return ret;
577 }
578 }
579
580 if (buf == root->node) {
581 WARN_ON(parent && parent != buf);
582 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
583 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
584 parent_start = buf->start;
585
586 atomic_inc(&cow->refs);
587 ret = btrfs_tree_mod_log_insert_root(root->node, cow, true);
588 BUG_ON(ret < 0);
589 rcu_assign_pointer(root->node, cow);
590
591 btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
592 parent_start, last_ref);
593 free_extent_buffer(buf);
594 add_root_to_dirty_list(root);
595 } else {
596 WARN_ON(trans->transid != btrfs_header_generation(parent));
597 btrfs_tree_mod_log_insert_key(parent, parent_slot,
598 BTRFS_MOD_LOG_KEY_REPLACE);
599 btrfs_set_node_blockptr(parent, parent_slot,
600 cow->start);
601 btrfs_set_node_ptr_generation(parent, parent_slot,
602 trans->transid);
603 btrfs_mark_buffer_dirty(parent);
604 if (last_ref) {
605 ret = btrfs_tree_mod_log_free_eb(buf);
606 if (ret) {
607 btrfs_tree_unlock(cow);
608 free_extent_buffer(cow);
609 btrfs_abort_transaction(trans, ret);
610 return ret;
611 }
612 }
613 btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
614 parent_start, last_ref);
615 }
616 if (unlock_orig)
617 btrfs_tree_unlock(buf);
618 free_extent_buffer_stale(buf);
619 btrfs_mark_buffer_dirty(cow);
620 *cow_ret = cow;
621 return 0;
622}
623
624static inline int should_cow_block(struct btrfs_trans_handle *trans,
625 struct btrfs_root *root,
626 struct extent_buffer *buf)
627{
628 if (btrfs_is_testing(root->fs_info))
629 return 0;
630
631 /* Ensure we can see the FORCE_COW bit */
632 smp_mb__before_atomic();
633
634 /*
635 * We do not need to cow a block if
636 * 1) this block is not created or changed in this transaction;
637 * 2) this block does not belong to TREE_RELOC tree;
638 * 3) the root is not forced COW.
639 *
640 * What is forced COW:
641 * when we create snapshot during committing the transaction,
642 * after we've finished copying src root, we must COW the shared
643 * block to ensure the metadata consistency.
644 */
645 if (btrfs_header_generation(buf) == trans->transid &&
646 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
647 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
648 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
649 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
650 return 0;
651 return 1;
652}
653
654/*
655 * cows a single block, see __btrfs_cow_block for the real work.
656 * This version of it has extra checks so that a block isn't COWed more than
657 * once per transaction, as long as it hasn't been written yet
658 */
659noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
660 struct btrfs_root *root, struct extent_buffer *buf,
661 struct extent_buffer *parent, int parent_slot,
662 struct extent_buffer **cow_ret,
663 enum btrfs_lock_nesting nest)
664{
665 struct btrfs_fs_info *fs_info = root->fs_info;
666 u64 search_start;
667 int ret;
668
669 if (test_bit(BTRFS_ROOT_DELETING, &root->state))
670 btrfs_err(fs_info,
671 "COW'ing blocks on a fs root that's being dropped");
672
673 if (trans->transaction != fs_info->running_transaction)
674 WARN(1, KERN_CRIT "trans %llu running %llu\n",
675 trans->transid,
676 fs_info->running_transaction->transid);
677
678 if (trans->transid != fs_info->generation)
679 WARN(1, KERN_CRIT "trans %llu running %llu\n",
680 trans->transid, fs_info->generation);
681
682 if (!should_cow_block(trans, root, buf)) {
683 *cow_ret = buf;
684 return 0;
685 }
686
687 search_start = buf->start & ~((u64)SZ_1G - 1);
688
689 /*
690 * Before CoWing this block for later modification, check if it's
691 * the subtree root and do the delayed subtree trace if needed.
692 *
693 * Also We don't care about the error, as it's handled internally.
694 */
695 btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
696 ret = __btrfs_cow_block(trans, root, buf, parent,
697 parent_slot, cow_ret, search_start, 0, nest);
698
699 trace_btrfs_cow_block(root, buf, *cow_ret);
700
701 return ret;
702}
703ALLOW_ERROR_INJECTION(btrfs_cow_block, ERRNO);
704
705/*
706 * helper function for defrag to decide if two blocks pointed to by a
707 * node are actually close by
708 */
709static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
710{
711 if (blocknr < other && other - (blocknr + blocksize) < 32768)
712 return 1;
713 if (blocknr > other && blocknr - (other + blocksize) < 32768)
714 return 1;
715 return 0;
716}
717
718#ifdef __LITTLE_ENDIAN
719
720/*
721 * Compare two keys, on little-endian the disk order is same as CPU order and
722 * we can avoid the conversion.
723 */
724static int comp_keys(const struct btrfs_disk_key *disk_key,
725 const struct btrfs_key *k2)
726{
727 const struct btrfs_key *k1 = (const struct btrfs_key *)disk_key;
728
729 return btrfs_comp_cpu_keys(k1, k2);
730}
731
732#else
733
734/*
735 * compare two keys in a memcmp fashion
736 */
737static int comp_keys(const struct btrfs_disk_key *disk,
738 const struct btrfs_key *k2)
739{
740 struct btrfs_key k1;
741
742 btrfs_disk_key_to_cpu(&k1, disk);
743
744 return btrfs_comp_cpu_keys(&k1, k2);
745}
746#endif
747
748/*
749 * same as comp_keys only with two btrfs_key's
750 */
751int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
752{
753 if (k1->objectid > k2->objectid)
754 return 1;
755 if (k1->objectid < k2->objectid)
756 return -1;
757 if (k1->type > k2->type)
758 return 1;
759 if (k1->type < k2->type)
760 return -1;
761 if (k1->offset > k2->offset)
762 return 1;
763 if (k1->offset < k2->offset)
764 return -1;
765 return 0;
766}
767
768/*
769 * this is used by the defrag code to go through all the
770 * leaves pointed to by a node and reallocate them so that
771 * disk order is close to key order
772 */
773int btrfs_realloc_node(struct btrfs_trans_handle *trans,
774 struct btrfs_root *root, struct extent_buffer *parent,
775 int start_slot, u64 *last_ret,
776 struct btrfs_key *progress)
777{
778 struct btrfs_fs_info *fs_info = root->fs_info;
779 struct extent_buffer *cur;
780 u64 blocknr;
781 u64 search_start = *last_ret;
782 u64 last_block = 0;
783 u64 other;
784 u32 parent_nritems;
785 int end_slot;
786 int i;
787 int err = 0;
788 u32 blocksize;
789 int progress_passed = 0;
790 struct btrfs_disk_key disk_key;
791
792 WARN_ON(trans->transaction != fs_info->running_transaction);
793 WARN_ON(trans->transid != fs_info->generation);
794
795 parent_nritems = btrfs_header_nritems(parent);
796 blocksize = fs_info->nodesize;
797 end_slot = parent_nritems - 1;
798
799 if (parent_nritems <= 1)
800 return 0;
801
802 for (i = start_slot; i <= end_slot; i++) {
803 int close = 1;
804
805 btrfs_node_key(parent, &disk_key, i);
806 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
807 continue;
808
809 progress_passed = 1;
810 blocknr = btrfs_node_blockptr(parent, i);
811 if (last_block == 0)
812 last_block = blocknr;
813
814 if (i > 0) {
815 other = btrfs_node_blockptr(parent, i - 1);
816 close = close_blocks(blocknr, other, blocksize);
817 }
818 if (!close && i < end_slot) {
819 other = btrfs_node_blockptr(parent, i + 1);
820 close = close_blocks(blocknr, other, blocksize);
821 }
822 if (close) {
823 last_block = blocknr;
824 continue;
825 }
826
827 cur = btrfs_read_node_slot(parent, i);
828 if (IS_ERR(cur))
829 return PTR_ERR(cur);
830 if (search_start == 0)
831 search_start = last_block;
832
833 btrfs_tree_lock(cur);
834 err = __btrfs_cow_block(trans, root, cur, parent, i,
835 &cur, search_start,
836 min(16 * blocksize,
837 (end_slot - i) * blocksize),
838 BTRFS_NESTING_COW);
839 if (err) {
840 btrfs_tree_unlock(cur);
841 free_extent_buffer(cur);
842 break;
843 }
844 search_start = cur->start;
845 last_block = cur->start;
846 *last_ret = search_start;
847 btrfs_tree_unlock(cur);
848 free_extent_buffer(cur);
849 }
850 return err;
851}
852
853/*
854 * Search for a key in the given extent_buffer.
855 *
856 * The lower boundary for the search is specified by the slot number @low. Use a
857 * value of 0 to search over the whole extent buffer.
858 *
859 * The slot in the extent buffer is returned via @slot. If the key exists in the
860 * extent buffer, then @slot will point to the slot where the key is, otherwise
861 * it points to the slot where you would insert the key.
862 *
863 * Slot may point to the total number of items (i.e. one position beyond the last
864 * key) if the key is bigger than the last key in the extent buffer.
865 */
866static noinline int generic_bin_search(struct extent_buffer *eb, int low,
867 const struct btrfs_key *key, int *slot)
868{
869 unsigned long p;
870 int item_size;
871 int high = btrfs_header_nritems(eb);
872 int ret;
873 const int key_size = sizeof(struct btrfs_disk_key);
874
875 if (low > high) {
876 btrfs_err(eb->fs_info,
877 "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
878 __func__, low, high, eb->start,
879 btrfs_header_owner(eb), btrfs_header_level(eb));
880 return -EINVAL;
881 }
882
883 if (btrfs_header_level(eb) == 0) {
884 p = offsetof(struct btrfs_leaf, items);
885 item_size = sizeof(struct btrfs_item);
886 } else {
887 p = offsetof(struct btrfs_node, ptrs);
888 item_size = sizeof(struct btrfs_key_ptr);
889 }
890
891 while (low < high) {
892 unsigned long oip;
893 unsigned long offset;
894 struct btrfs_disk_key *tmp;
895 struct btrfs_disk_key unaligned;
896 int mid;
897
898 mid = (low + high) / 2;
899 offset = p + mid * item_size;
900 oip = offset_in_page(offset);
901
902 if (oip + key_size <= PAGE_SIZE) {
903 const unsigned long idx = get_eb_page_index(offset);
904 char *kaddr = page_address(eb->pages[idx]);
905
906 oip = get_eb_offset_in_page(eb, offset);
907 tmp = (struct btrfs_disk_key *)(kaddr + oip);
908 } else {
909 read_extent_buffer(eb, &unaligned, offset, key_size);
910 tmp = &unaligned;
911 }
912
913 ret = comp_keys(tmp, key);
914
915 if (ret < 0)
916 low = mid + 1;
917 else if (ret > 0)
918 high = mid;
919 else {
920 *slot = mid;
921 return 0;
922 }
923 }
924 *slot = low;
925 return 1;
926}
927
928/*
929 * Simple binary search on an extent buffer. Works for both leaves and nodes, and
930 * always searches over the whole range of keys (slot 0 to slot 'nritems - 1').
931 */
932int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
933 int *slot)
934{
935 return generic_bin_search(eb, 0, key, slot);
936}
937
938static void root_add_used(struct btrfs_root *root, u32 size)
939{
940 spin_lock(&root->accounting_lock);
941 btrfs_set_root_used(&root->root_item,
942 btrfs_root_used(&root->root_item) + size);
943 spin_unlock(&root->accounting_lock);
944}
945
946static void root_sub_used(struct btrfs_root *root, u32 size)
947{
948 spin_lock(&root->accounting_lock);
949 btrfs_set_root_used(&root->root_item,
950 btrfs_root_used(&root->root_item) - size);
951 spin_unlock(&root->accounting_lock);
952}
953
954/* given a node and slot number, this reads the blocks it points to. The
955 * extent buffer is returned with a reference taken (but unlocked).
956 */
957struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
958 int slot)
959{
960 int level = btrfs_header_level(parent);
961 struct btrfs_tree_parent_check check = { 0 };
962 struct extent_buffer *eb;
963
964 if (slot < 0 || slot >= btrfs_header_nritems(parent))
965 return ERR_PTR(-ENOENT);
966
967 BUG_ON(level == 0);
968
969 check.level = level - 1;
970 check.transid = btrfs_node_ptr_generation(parent, slot);
971 check.owner_root = btrfs_header_owner(parent);
972 check.has_first_key = true;
973 btrfs_node_key_to_cpu(parent, &check.first_key, slot);
974
975 eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
976 &check);
977 if (IS_ERR(eb))
978 return eb;
979 if (!extent_buffer_uptodate(eb)) {
980 free_extent_buffer(eb);
981 return ERR_PTR(-EIO);
982 }
983
984 return eb;
985}
986
987/*
988 * node level balancing, used to make sure nodes are in proper order for
989 * item deletion. We balance from the top down, so we have to make sure
990 * that a deletion won't leave an node completely empty later on.
991 */
992static noinline int balance_level(struct btrfs_trans_handle *trans,
993 struct btrfs_root *root,
994 struct btrfs_path *path, int level)
995{
996 struct btrfs_fs_info *fs_info = root->fs_info;
997 struct extent_buffer *right = NULL;
998 struct extent_buffer *mid;
999 struct extent_buffer *left = NULL;
1000 struct extent_buffer *parent = NULL;
1001 int ret = 0;
1002 int wret;
1003 int pslot;
1004 int orig_slot = path->slots[level];
1005 u64 orig_ptr;
1006
1007 ASSERT(level > 0);
1008
1009 mid = path->nodes[level];
1010
1011 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK);
1012 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1013
1014 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1015
1016 if (level < BTRFS_MAX_LEVEL - 1) {
1017 parent = path->nodes[level + 1];
1018 pslot = path->slots[level + 1];
1019 }
1020
1021 /*
1022 * deal with the case where there is only one pointer in the root
1023 * by promoting the node below to a root
1024 */
1025 if (!parent) {
1026 struct extent_buffer *child;
1027
1028 if (btrfs_header_nritems(mid) != 1)
1029 return 0;
1030
1031 /* promote the child to a root */
1032 child = btrfs_read_node_slot(mid, 0);
1033 if (IS_ERR(child)) {
1034 ret = PTR_ERR(child);
1035 btrfs_handle_fs_error(fs_info, ret, NULL);
1036 goto enospc;
1037 }
1038
1039 btrfs_tree_lock(child);
1040 ret = btrfs_cow_block(trans, root, child, mid, 0, &child,
1041 BTRFS_NESTING_COW);
1042 if (ret) {
1043 btrfs_tree_unlock(child);
1044 free_extent_buffer(child);
1045 goto enospc;
1046 }
1047
1048 ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
1049 BUG_ON(ret < 0);
1050 rcu_assign_pointer(root->node, child);
1051
1052 add_root_to_dirty_list(root);
1053 btrfs_tree_unlock(child);
1054
1055 path->locks[level] = 0;
1056 path->nodes[level] = NULL;
1057 btrfs_clean_tree_block(mid);
1058 btrfs_tree_unlock(mid);
1059 /* once for the path */
1060 free_extent_buffer(mid);
1061
1062 root_sub_used(root, mid->len);
1063 btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
1064 /* once for the root ptr */
1065 free_extent_buffer_stale(mid);
1066 return 0;
1067 }
1068 if (btrfs_header_nritems(mid) >
1069 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
1070 return 0;
1071
1072 left = btrfs_read_node_slot(parent, pslot - 1);
1073 if (IS_ERR(left))
1074 left = NULL;
1075
1076 if (left) {
1077 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
1078 wret = btrfs_cow_block(trans, root, left,
1079 parent, pslot - 1, &left,
1080 BTRFS_NESTING_LEFT_COW);
1081 if (wret) {
1082 ret = wret;
1083 goto enospc;
1084 }
1085 }
1086
1087 right = btrfs_read_node_slot(parent, pslot + 1);
1088 if (IS_ERR(right))
1089 right = NULL;
1090
1091 if (right) {
1092 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
1093 wret = btrfs_cow_block(trans, root, right,
1094 parent, pslot + 1, &right,
1095 BTRFS_NESTING_RIGHT_COW);
1096 if (wret) {
1097 ret = wret;
1098 goto enospc;
1099 }
1100 }
1101
1102 /* first, try to make some room in the middle buffer */
1103 if (left) {
1104 orig_slot += btrfs_header_nritems(left);
1105 wret = push_node_left(trans, left, mid, 1);
1106 if (wret < 0)
1107 ret = wret;
1108 }
1109
1110 /*
1111 * then try to empty the right most buffer into the middle
1112 */
1113 if (right) {
1114 wret = push_node_left(trans, mid, right, 1);
1115 if (wret < 0 && wret != -ENOSPC)
1116 ret = wret;
1117 if (btrfs_header_nritems(right) == 0) {
1118 btrfs_clean_tree_block(right);
1119 btrfs_tree_unlock(right);
1120 del_ptr(root, path, level + 1, pslot + 1);
1121 root_sub_used(root, right->len);
1122 btrfs_free_tree_block(trans, btrfs_root_id(root), right,
1123 0, 1);
1124 free_extent_buffer_stale(right);
1125 right = NULL;
1126 } else {
1127 struct btrfs_disk_key right_key;
1128 btrfs_node_key(right, &right_key, 0);
1129 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1130 BTRFS_MOD_LOG_KEY_REPLACE);
1131 BUG_ON(ret < 0);
1132 btrfs_set_node_key(parent, &right_key, pslot + 1);
1133 btrfs_mark_buffer_dirty(parent);
1134 }
1135 }
1136 if (btrfs_header_nritems(mid) == 1) {
1137 /*
1138 * we're not allowed to leave a node with one item in the
1139 * tree during a delete. A deletion from lower in the tree
1140 * could try to delete the only pointer in this node.
1141 * So, pull some keys from the left.
1142 * There has to be a left pointer at this point because
1143 * otherwise we would have pulled some pointers from the
1144 * right
1145 */
1146 if (!left) {
1147 ret = -EROFS;
1148 btrfs_handle_fs_error(fs_info, ret, NULL);
1149 goto enospc;
1150 }
1151 wret = balance_node_right(trans, mid, left);
1152 if (wret < 0) {
1153 ret = wret;
1154 goto enospc;
1155 }
1156 if (wret == 1) {
1157 wret = push_node_left(trans, left, mid, 1);
1158 if (wret < 0)
1159 ret = wret;
1160 }
1161 BUG_ON(wret == 1);
1162 }
1163 if (btrfs_header_nritems(mid) == 0) {
1164 btrfs_clean_tree_block(mid);
1165 btrfs_tree_unlock(mid);
1166 del_ptr(root, path, level + 1, pslot);
1167 root_sub_used(root, mid->len);
1168 btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
1169 free_extent_buffer_stale(mid);
1170 mid = NULL;
1171 } else {
1172 /* update the parent key to reflect our changes */
1173 struct btrfs_disk_key mid_key;
1174 btrfs_node_key(mid, &mid_key, 0);
1175 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1176 BTRFS_MOD_LOG_KEY_REPLACE);
1177 BUG_ON(ret < 0);
1178 btrfs_set_node_key(parent, &mid_key, pslot);
1179 btrfs_mark_buffer_dirty(parent);
1180 }
1181
1182 /* update the path */
1183 if (left) {
1184 if (btrfs_header_nritems(left) > orig_slot) {
1185 atomic_inc(&left->refs);
1186 /* left was locked after cow */
1187 path->nodes[level] = left;
1188 path->slots[level + 1] -= 1;
1189 path->slots[level] = orig_slot;
1190 if (mid) {
1191 btrfs_tree_unlock(mid);
1192 free_extent_buffer(mid);
1193 }
1194 } else {
1195 orig_slot -= btrfs_header_nritems(left);
1196 path->slots[level] = orig_slot;
1197 }
1198 }
1199 /* double check we haven't messed things up */
1200 if (orig_ptr !=
1201 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1202 BUG();
1203enospc:
1204 if (right) {
1205 btrfs_tree_unlock(right);
1206 free_extent_buffer(right);
1207 }
1208 if (left) {
1209 if (path->nodes[level] != left)
1210 btrfs_tree_unlock(left);
1211 free_extent_buffer(left);
1212 }
1213 return ret;
1214}
1215
1216/* Node balancing for insertion. Here we only split or push nodes around
1217 * when they are completely full. This is also done top down, so we
1218 * have to be pessimistic.
1219 */
1220static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1221 struct btrfs_root *root,
1222 struct btrfs_path *path, int level)
1223{
1224 struct btrfs_fs_info *fs_info = root->fs_info;
1225 struct extent_buffer *right = NULL;
1226 struct extent_buffer *mid;
1227 struct extent_buffer *left = NULL;
1228 struct extent_buffer *parent = NULL;
1229 int ret = 0;
1230 int wret;
1231 int pslot;
1232 int orig_slot = path->slots[level];
1233
1234 if (level == 0)
1235 return 1;
1236
1237 mid = path->nodes[level];
1238 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1239
1240 if (level < BTRFS_MAX_LEVEL - 1) {
1241 parent = path->nodes[level + 1];
1242 pslot = path->slots[level + 1];
1243 }
1244
1245 if (!parent)
1246 return 1;
1247
1248 left = btrfs_read_node_slot(parent, pslot - 1);
1249 if (IS_ERR(left))
1250 left = NULL;
1251
1252 /* first, try to make some room in the middle buffer */
1253 if (left) {
1254 u32 left_nr;
1255
1256 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
1257
1258 left_nr = btrfs_header_nritems(left);
1259 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1260 wret = 1;
1261 } else {
1262 ret = btrfs_cow_block(trans, root, left, parent,
1263 pslot - 1, &left,
1264 BTRFS_NESTING_LEFT_COW);
1265 if (ret)
1266 wret = 1;
1267 else {
1268 wret = push_node_left(trans, left, mid, 0);
1269 }
1270 }
1271 if (wret < 0)
1272 ret = wret;
1273 if (wret == 0) {
1274 struct btrfs_disk_key disk_key;
1275 orig_slot += left_nr;
1276 btrfs_node_key(mid, &disk_key, 0);
1277 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1278 BTRFS_MOD_LOG_KEY_REPLACE);
1279 BUG_ON(ret < 0);
1280 btrfs_set_node_key(parent, &disk_key, pslot);
1281 btrfs_mark_buffer_dirty(parent);
1282 if (btrfs_header_nritems(left) > orig_slot) {
1283 path->nodes[level] = left;
1284 path->slots[level + 1] -= 1;
1285 path->slots[level] = orig_slot;
1286 btrfs_tree_unlock(mid);
1287 free_extent_buffer(mid);
1288 } else {
1289 orig_slot -=
1290 btrfs_header_nritems(left);
1291 path->slots[level] = orig_slot;
1292 btrfs_tree_unlock(left);
1293 free_extent_buffer(left);
1294 }
1295 return 0;
1296 }
1297 btrfs_tree_unlock(left);
1298 free_extent_buffer(left);
1299 }
1300 right = btrfs_read_node_slot(parent, pslot + 1);
1301 if (IS_ERR(right))
1302 right = NULL;
1303
1304 /*
1305 * then try to empty the right most buffer into the middle
1306 */
1307 if (right) {
1308 u32 right_nr;
1309
1310 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
1311
1312 right_nr = btrfs_header_nritems(right);
1313 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1314 wret = 1;
1315 } else {
1316 ret = btrfs_cow_block(trans, root, right,
1317 parent, pslot + 1,
1318 &right, BTRFS_NESTING_RIGHT_COW);
1319 if (ret)
1320 wret = 1;
1321 else {
1322 wret = balance_node_right(trans, right, mid);
1323 }
1324 }
1325 if (wret < 0)
1326 ret = wret;
1327 if (wret == 0) {
1328 struct btrfs_disk_key disk_key;
1329
1330 btrfs_node_key(right, &disk_key, 0);
1331 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1332 BTRFS_MOD_LOG_KEY_REPLACE);
1333 BUG_ON(ret < 0);
1334 btrfs_set_node_key(parent, &disk_key, pslot + 1);
1335 btrfs_mark_buffer_dirty(parent);
1336
1337 if (btrfs_header_nritems(mid) <= orig_slot) {
1338 path->nodes[level] = right;
1339 path->slots[level + 1] += 1;
1340 path->slots[level] = orig_slot -
1341 btrfs_header_nritems(mid);
1342 btrfs_tree_unlock(mid);
1343 free_extent_buffer(mid);
1344 } else {
1345 btrfs_tree_unlock(right);
1346 free_extent_buffer(right);
1347 }
1348 return 0;
1349 }
1350 btrfs_tree_unlock(right);
1351 free_extent_buffer(right);
1352 }
1353 return 1;
1354}
1355
1356/*
1357 * readahead one full node of leaves, finding things that are close
1358 * to the block in 'slot', and triggering ra on them.
1359 */
1360static void reada_for_search(struct btrfs_fs_info *fs_info,
1361 struct btrfs_path *path,
1362 int level, int slot, u64 objectid)
1363{
1364 struct extent_buffer *node;
1365 struct btrfs_disk_key disk_key;
1366 u32 nritems;
1367 u64 search;
1368 u64 target;
1369 u64 nread = 0;
1370 u64 nread_max;
1371 u32 nr;
1372 u32 blocksize;
1373 u32 nscan = 0;
1374
1375 if (level != 1 && path->reada != READA_FORWARD_ALWAYS)
1376 return;
1377
1378 if (!path->nodes[level])
1379 return;
1380
1381 node = path->nodes[level];
1382
1383 /*
1384 * Since the time between visiting leaves is much shorter than the time
1385 * between visiting nodes, limit read ahead of nodes to 1, to avoid too
1386 * much IO at once (possibly random).
1387 */
1388 if (path->reada == READA_FORWARD_ALWAYS) {
1389 if (level > 1)
1390 nread_max = node->fs_info->nodesize;
1391 else
1392 nread_max = SZ_128K;
1393 } else {
1394 nread_max = SZ_64K;
1395 }
1396
1397 search = btrfs_node_blockptr(node, slot);
1398 blocksize = fs_info->nodesize;
1399 if (path->reada != READA_FORWARD_ALWAYS) {
1400 struct extent_buffer *eb;
1401
1402 eb = find_extent_buffer(fs_info, search);
1403 if (eb) {
1404 free_extent_buffer(eb);
1405 return;
1406 }
1407 }
1408
1409 target = search;
1410
1411 nritems = btrfs_header_nritems(node);
1412 nr = slot;
1413
1414 while (1) {
1415 if (path->reada == READA_BACK) {
1416 if (nr == 0)
1417 break;
1418 nr--;
1419 } else if (path->reada == READA_FORWARD ||
1420 path->reada == READA_FORWARD_ALWAYS) {
1421 nr++;
1422 if (nr >= nritems)
1423 break;
1424 }
1425 if (path->reada == READA_BACK && objectid) {
1426 btrfs_node_key(node, &disk_key, nr);
1427 if (btrfs_disk_key_objectid(&disk_key) != objectid)
1428 break;
1429 }
1430 search = btrfs_node_blockptr(node, nr);
1431 if (path->reada == READA_FORWARD_ALWAYS ||
1432 (search <= target && target - search <= 65536) ||
1433 (search > target && search - target <= 65536)) {
1434 btrfs_readahead_node_child(node, nr);
1435 nread += blocksize;
1436 }
1437 nscan++;
1438 if (nread > nread_max || nscan > 32)
1439 break;
1440 }
1441}
1442
1443static noinline void reada_for_balance(struct btrfs_path *path, int level)
1444{
1445 struct extent_buffer *parent;
1446 int slot;
1447 int nritems;
1448
1449 parent = path->nodes[level + 1];
1450 if (!parent)
1451 return;
1452
1453 nritems = btrfs_header_nritems(parent);
1454 slot = path->slots[level + 1];
1455
1456 if (slot > 0)
1457 btrfs_readahead_node_child(parent, slot - 1);
1458 if (slot + 1 < nritems)
1459 btrfs_readahead_node_child(parent, slot + 1);
1460}
1461
1462
1463/*
1464 * when we walk down the tree, it is usually safe to unlock the higher layers
1465 * in the tree. The exceptions are when our path goes through slot 0, because
1466 * operations on the tree might require changing key pointers higher up in the
1467 * tree.
1468 *
1469 * callers might also have set path->keep_locks, which tells this code to keep
1470 * the lock if the path points to the last slot in the block. This is part of
1471 * walking through the tree, and selecting the next slot in the higher block.
1472 *
1473 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
1474 * if lowest_unlock is 1, level 0 won't be unlocked
1475 */
1476static noinline void unlock_up(struct btrfs_path *path, int level,
1477 int lowest_unlock, int min_write_lock_level,
1478 int *write_lock_level)
1479{
1480 int i;
1481 int skip_level = level;
1482 bool check_skip = true;
1483
1484 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1485 if (!path->nodes[i])
1486 break;
1487 if (!path->locks[i])
1488 break;
1489
1490 if (check_skip) {
1491 if (path->slots[i] == 0) {
1492 skip_level = i + 1;
1493 continue;
1494 }
1495
1496 if (path->keep_locks) {
1497 u32 nritems;
1498
1499 nritems = btrfs_header_nritems(path->nodes[i]);
1500 if (nritems < 1 || path->slots[i] >= nritems - 1) {
1501 skip_level = i + 1;
1502 continue;
1503 }
1504 }
1505 }
1506
1507 if (i >= lowest_unlock && i > skip_level) {
1508 check_skip = false;
1509 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
1510 path->locks[i] = 0;
1511 if (write_lock_level &&
1512 i > min_write_lock_level &&
1513 i <= *write_lock_level) {
1514 *write_lock_level = i - 1;
1515 }
1516 }
1517 }
1518}
1519
1520/*
1521 * Helper function for btrfs_search_slot() and other functions that do a search
1522 * on a btree. The goal is to find a tree block in the cache (the radix tree at
1523 * fs_info->buffer_radix), but if we can't find it, or it's not up to date, read
1524 * its pages from disk.
1525 *
1526 * Returns -EAGAIN, with the path unlocked, if the caller needs to repeat the
1527 * whole btree search, starting again from the current root node.
1528 */
1529static int
1530read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
1531 struct extent_buffer **eb_ret, int level, int slot,
1532 const struct btrfs_key *key)
1533{
1534 struct btrfs_fs_info *fs_info = root->fs_info;
1535 struct btrfs_tree_parent_check check = { 0 };
1536 u64 blocknr;
1537 u64 gen;
1538 struct extent_buffer *tmp;
1539 int ret;
1540 int parent_level;
1541 bool unlock_up;
1542
1543 unlock_up = ((level + 1 < BTRFS_MAX_LEVEL) && p->locks[level + 1]);
1544 blocknr = btrfs_node_blockptr(*eb_ret, slot);
1545 gen = btrfs_node_ptr_generation(*eb_ret, slot);
1546 parent_level = btrfs_header_level(*eb_ret);
1547 btrfs_node_key_to_cpu(*eb_ret, &check.first_key, slot);
1548 check.has_first_key = true;
1549 check.level = parent_level - 1;
1550 check.transid = gen;
1551 check.owner_root = root->root_key.objectid;
1552
1553 /*
1554 * If we need to read an extent buffer from disk and we are holding locks
1555 * on upper level nodes, we unlock all the upper nodes before reading the
1556 * extent buffer, and then return -EAGAIN to the caller as it needs to
1557 * restart the search. We don't release the lock on the current level
1558 * because we need to walk this node to figure out which blocks to read.
1559 */
1560 tmp = find_extent_buffer(fs_info, blocknr);
1561 if (tmp) {
1562 if (p->reada == READA_FORWARD_ALWAYS)
1563 reada_for_search(fs_info, p, level, slot, key->objectid);
1564
1565 /* first we do an atomic uptodate check */
1566 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
1567 /*
1568 * Do extra check for first_key, eb can be stale due to
1569 * being cached, read from scrub, or have multiple
1570 * parents (shared tree blocks).
1571 */
1572 if (btrfs_verify_level_key(tmp,
1573 parent_level - 1, &check.first_key, gen)) {
1574 free_extent_buffer(tmp);
1575 return -EUCLEAN;
1576 }
1577 *eb_ret = tmp;
1578 return 0;
1579 }
1580
1581 if (p->nowait) {
1582 free_extent_buffer(tmp);
1583 return -EAGAIN;
1584 }
1585
1586 if (unlock_up)
1587 btrfs_unlock_up_safe(p, level + 1);
1588
1589 /* now we're allowed to do a blocking uptodate check */
1590 ret = btrfs_read_extent_buffer(tmp, &check);
1591 if (ret) {
1592 free_extent_buffer(tmp);
1593 btrfs_release_path(p);
1594 return -EIO;
1595 }
1596 if (btrfs_check_eb_owner(tmp, root->root_key.objectid)) {
1597 free_extent_buffer(tmp);
1598 btrfs_release_path(p);
1599 return -EUCLEAN;
1600 }
1601
1602 if (unlock_up)
1603 ret = -EAGAIN;
1604
1605 goto out;
1606 } else if (p->nowait) {
1607 return -EAGAIN;
1608 }
1609
1610 if (unlock_up) {
1611 btrfs_unlock_up_safe(p, level + 1);
1612 ret = -EAGAIN;
1613 } else {
1614 ret = 0;
1615 }
1616
1617 if (p->reada != READA_NONE)
1618 reada_for_search(fs_info, p, level, slot, key->objectid);
1619
1620 tmp = read_tree_block(fs_info, blocknr, &check);
1621 if (IS_ERR(tmp)) {
1622 btrfs_release_path(p);
1623 return PTR_ERR(tmp);
1624 }
1625 /*
1626 * If the read above didn't mark this buffer up to date,
1627 * it will never end up being up to date. Set ret to EIO now
1628 * and give up so that our caller doesn't loop forever
1629 * on our EAGAINs.
1630 */
1631 if (!extent_buffer_uptodate(tmp))
1632 ret = -EIO;
1633
1634out:
1635 if (ret == 0) {
1636 *eb_ret = tmp;
1637 } else {
1638 free_extent_buffer(tmp);
1639 btrfs_release_path(p);
1640 }
1641
1642 return ret;
1643}
1644
1645/*
1646 * helper function for btrfs_search_slot. This does all of the checks
1647 * for node-level blocks and does any balancing required based on
1648 * the ins_len.
1649 *
1650 * If no extra work was required, zero is returned. If we had to
1651 * drop the path, -EAGAIN is returned and btrfs_search_slot must
1652 * start over
1653 */
1654static int
1655setup_nodes_for_search(struct btrfs_trans_handle *trans,
1656 struct btrfs_root *root, struct btrfs_path *p,
1657 struct extent_buffer *b, int level, int ins_len,
1658 int *write_lock_level)
1659{
1660 struct btrfs_fs_info *fs_info = root->fs_info;
1661 int ret = 0;
1662
1663 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
1664 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
1665
1666 if (*write_lock_level < level + 1) {
1667 *write_lock_level = level + 1;
1668 btrfs_release_path(p);
1669 return -EAGAIN;
1670 }
1671
1672 reada_for_balance(p, level);
1673 ret = split_node(trans, root, p, level);
1674
1675 b = p->nodes[level];
1676 } else if (ins_len < 0 && btrfs_header_nritems(b) <
1677 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
1678
1679 if (*write_lock_level < level + 1) {
1680 *write_lock_level = level + 1;
1681 btrfs_release_path(p);
1682 return -EAGAIN;
1683 }
1684
1685 reada_for_balance(p, level);
1686 ret = balance_level(trans, root, p, level);
1687 if (ret)
1688 return ret;
1689
1690 b = p->nodes[level];
1691 if (!b) {
1692 btrfs_release_path(p);
1693 return -EAGAIN;
1694 }
1695 BUG_ON(btrfs_header_nritems(b) == 1);
1696 }
1697 return ret;
1698}
1699
1700int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
1701 u64 iobjectid, u64 ioff, u8 key_type,
1702 struct btrfs_key *found_key)
1703{
1704 int ret;
1705 struct btrfs_key key;
1706 struct extent_buffer *eb;
1707
1708 ASSERT(path);
1709 ASSERT(found_key);
1710
1711 key.type = key_type;
1712 key.objectid = iobjectid;
1713 key.offset = ioff;
1714
1715 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1716 if (ret < 0)
1717 return ret;
1718
1719 eb = path->nodes[0];
1720 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1721 ret = btrfs_next_leaf(fs_root, path);
1722 if (ret)
1723 return ret;
1724 eb = path->nodes[0];
1725 }
1726
1727 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1728 if (found_key->type != key.type ||
1729 found_key->objectid != key.objectid)
1730 return 1;
1731
1732 return 0;
1733}
1734
1735static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
1736 struct btrfs_path *p,
1737 int write_lock_level)
1738{
1739 struct extent_buffer *b;
1740 int root_lock = 0;
1741 int level = 0;
1742
1743 if (p->search_commit_root) {
1744 b = root->commit_root;
1745 atomic_inc(&b->refs);
1746 level = btrfs_header_level(b);
1747 /*
1748 * Ensure that all callers have set skip_locking when
1749 * p->search_commit_root = 1.
1750 */
1751 ASSERT(p->skip_locking == 1);
1752
1753 goto out;
1754 }
1755
1756 if (p->skip_locking) {
1757 b = btrfs_root_node(root);
1758 level = btrfs_header_level(b);
1759 goto out;
1760 }
1761
1762 /* We try very hard to do read locks on the root */
1763 root_lock = BTRFS_READ_LOCK;
1764
1765 /*
1766 * If the level is set to maximum, we can skip trying to get the read
1767 * lock.
1768 */
1769 if (write_lock_level < BTRFS_MAX_LEVEL) {
1770 /*
1771 * We don't know the level of the root node until we actually
1772 * have it read locked
1773 */
1774 if (p->nowait) {
1775 b = btrfs_try_read_lock_root_node(root);
1776 if (IS_ERR(b))
1777 return b;
1778 } else {
1779 b = btrfs_read_lock_root_node(root);
1780 }
1781 level = btrfs_header_level(b);
1782 if (level > write_lock_level)
1783 goto out;
1784
1785 /* Whoops, must trade for write lock */
1786 btrfs_tree_read_unlock(b);
1787 free_extent_buffer(b);
1788 }
1789
1790 b = btrfs_lock_root_node(root);
1791 root_lock = BTRFS_WRITE_LOCK;
1792
1793 /* The level might have changed, check again */
1794 level = btrfs_header_level(b);
1795
1796out:
1797 /*
1798 * The root may have failed to write out at some point, and thus is no
1799 * longer valid, return an error in this case.
1800 */
1801 if (!extent_buffer_uptodate(b)) {
1802 if (root_lock)
1803 btrfs_tree_unlock_rw(b, root_lock);
1804 free_extent_buffer(b);
1805 return ERR_PTR(-EIO);
1806 }
1807
1808 p->nodes[level] = b;
1809 if (!p->skip_locking)
1810 p->locks[level] = root_lock;
1811 /*
1812 * Callers are responsible for dropping b's references.
1813 */
1814 return b;
1815}
1816
1817/*
1818 * Replace the extent buffer at the lowest level of the path with a cloned
1819 * version. The purpose is to be able to use it safely, after releasing the
1820 * commit root semaphore, even if relocation is happening in parallel, the
1821 * transaction used for relocation is committed and the extent buffer is
1822 * reallocated in the next transaction.
1823 *
1824 * This is used in a context where the caller does not prevent transaction
1825 * commits from happening, either by holding a transaction handle or holding
1826 * some lock, while it's doing searches through a commit root.
1827 * At the moment it's only used for send operations.
1828 */
1829static int finish_need_commit_sem_search(struct btrfs_path *path)
1830{
1831 const int i = path->lowest_level;
1832 const int slot = path->slots[i];
1833 struct extent_buffer *lowest = path->nodes[i];
1834 struct extent_buffer *clone;
1835
1836 ASSERT(path->need_commit_sem);
1837
1838 if (!lowest)
1839 return 0;
1840
1841 lockdep_assert_held_read(&lowest->fs_info->commit_root_sem);
1842
1843 clone = btrfs_clone_extent_buffer(lowest);
1844 if (!clone)
1845 return -ENOMEM;
1846
1847 btrfs_release_path(path);
1848 path->nodes[i] = clone;
1849 path->slots[i] = slot;
1850
1851 return 0;
1852}
1853
1854static inline int search_for_key_slot(struct extent_buffer *eb,
1855 int search_low_slot,
1856 const struct btrfs_key *key,
1857 int prev_cmp,
1858 int *slot)
1859{
1860 /*
1861 * If a previous call to btrfs_bin_search() on a parent node returned an
1862 * exact match (prev_cmp == 0), we can safely assume the target key will
1863 * always be at slot 0 on lower levels, since each key pointer
1864 * (struct btrfs_key_ptr) refers to the lowest key accessible from the
1865 * subtree it points to. Thus we can skip searching lower levels.
1866 */
1867 if (prev_cmp == 0) {
1868 *slot = 0;
1869 return 0;
1870 }
1871
1872 return generic_bin_search(eb, search_low_slot, key, slot);
1873}
1874
1875static int search_leaf(struct btrfs_trans_handle *trans,
1876 struct btrfs_root *root,
1877 const struct btrfs_key *key,
1878 struct btrfs_path *path,
1879 int ins_len,
1880 int prev_cmp)
1881{
1882 struct extent_buffer *leaf = path->nodes[0];
1883 int leaf_free_space = -1;
1884 int search_low_slot = 0;
1885 int ret;
1886 bool do_bin_search = true;
1887
1888 /*
1889 * If we are doing an insertion, the leaf has enough free space and the
1890 * destination slot for the key is not slot 0, then we can unlock our
1891 * write lock on the parent, and any other upper nodes, before doing the
1892 * binary search on the leaf (with search_for_key_slot()), allowing other
1893 * tasks to lock the parent and any other upper nodes.
1894 */
1895 if (ins_len > 0) {
1896 /*
1897 * Cache the leaf free space, since we will need it later and it
1898 * will not change until then.
1899 */
1900 leaf_free_space = btrfs_leaf_free_space(leaf);
1901
1902 /*
1903 * !path->locks[1] means we have a single node tree, the leaf is
1904 * the root of the tree.
1905 */
1906 if (path->locks[1] && leaf_free_space >= ins_len) {
1907 struct btrfs_disk_key first_key;
1908
1909 ASSERT(btrfs_header_nritems(leaf) > 0);
1910 btrfs_item_key(leaf, &first_key, 0);
1911
1912 /*
1913 * Doing the extra comparison with the first key is cheap,
1914 * taking into account that the first key is very likely
1915 * already in a cache line because it immediately follows
1916 * the extent buffer's header and we have recently accessed
1917 * the header's level field.
1918 */
1919 ret = comp_keys(&first_key, key);
1920 if (ret < 0) {
1921 /*
1922 * The first key is smaller than the key we want
1923 * to insert, so we are safe to unlock all upper
1924 * nodes and we have to do the binary search.
1925 *
1926 * We do use btrfs_unlock_up_safe() and not
1927 * unlock_up() because the later does not unlock
1928 * nodes with a slot of 0 - we can safely unlock
1929 * any node even if its slot is 0 since in this
1930 * case the key does not end up at slot 0 of the
1931 * leaf and there's no need to split the leaf.
1932 */
1933 btrfs_unlock_up_safe(path, 1);
1934 search_low_slot = 1;
1935 } else {
1936 /*
1937 * The first key is >= then the key we want to
1938 * insert, so we can skip the binary search as
1939 * the target key will be at slot 0.
1940 *
1941 * We can not unlock upper nodes when the key is
1942 * less than the first key, because we will need
1943 * to update the key at slot 0 of the parent node
1944 * and possibly of other upper nodes too.
1945 * If the key matches the first key, then we can
1946 * unlock all the upper nodes, using
1947 * btrfs_unlock_up_safe() instead of unlock_up()
1948 * as stated above.
1949 */
1950 if (ret == 0)
1951 btrfs_unlock_up_safe(path, 1);
1952 /*
1953 * ret is already 0 or 1, matching the result of
1954 * a btrfs_bin_search() call, so there is no need
1955 * to adjust it.
1956 */
1957 do_bin_search = false;
1958 path->slots[0] = 0;
1959 }
1960 }
1961 }
1962
1963 if (do_bin_search) {
1964 ret = search_for_key_slot(leaf, search_low_slot, key,
1965 prev_cmp, &path->slots[0]);
1966 if (ret < 0)
1967 return ret;
1968 }
1969
1970 if (ins_len > 0) {
1971 /*
1972 * Item key already exists. In this case, if we are allowed to
1973 * insert the item (for example, in dir_item case, item key
1974 * collision is allowed), it will be merged with the original
1975 * item. Only the item size grows, no new btrfs item will be
1976 * added. If search_for_extension is not set, ins_len already
1977 * accounts the size btrfs_item, deduct it here so leaf space
1978 * check will be correct.
1979 */
1980 if (ret == 0 && !path->search_for_extension) {
1981 ASSERT(ins_len >= sizeof(struct btrfs_item));
1982 ins_len -= sizeof(struct btrfs_item);
1983 }
1984
1985 ASSERT(leaf_free_space >= 0);
1986
1987 if (leaf_free_space < ins_len) {
1988 int err;
1989
1990 err = split_leaf(trans, root, key, path, ins_len,
1991 (ret == 0));
1992 ASSERT(err <= 0);
1993 if (WARN_ON(err > 0))
1994 err = -EUCLEAN;
1995 if (err)
1996 ret = err;
1997 }
1998 }
1999
2000 return ret;
2001}
2002
2003/*
2004 * btrfs_search_slot - look for a key in a tree and perform necessary
2005 * modifications to preserve tree invariants.
2006 *
2007 * @trans: Handle of transaction, used when modifying the tree
2008 * @p: Holds all btree nodes along the search path
2009 * @root: The root node of the tree
2010 * @key: The key we are looking for
2011 * @ins_len: Indicates purpose of search:
2012 * >0 for inserts it's size of item inserted (*)
2013 * <0 for deletions
2014 * 0 for plain searches, not modifying the tree
2015 *
2016 * (*) If size of item inserted doesn't include
2017 * sizeof(struct btrfs_item), then p->search_for_extension must
2018 * be set.
2019 * @cow: boolean should CoW operations be performed. Must always be 1
2020 * when modifying the tree.
2021 *
2022 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
2023 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
2024 *
2025 * If @key is found, 0 is returned and you can find the item in the leaf level
2026 * of the path (level 0)
2027 *
2028 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
2029 * points to the slot where it should be inserted
2030 *
2031 * If an error is encountered while searching the tree a negative error number
2032 * is returned
2033 */
2034int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2035 const struct btrfs_key *key, struct btrfs_path *p,
2036 int ins_len, int cow)
2037{
2038 struct btrfs_fs_info *fs_info = root->fs_info;
2039 struct extent_buffer *b;
2040 int slot;
2041 int ret;
2042 int err;
2043 int level;
2044 int lowest_unlock = 1;
2045 /* everything at write_lock_level or lower must be write locked */
2046 int write_lock_level = 0;
2047 u8 lowest_level = 0;
2048 int min_write_lock_level;
2049 int prev_cmp;
2050
2051 might_sleep();
2052
2053 lowest_level = p->lowest_level;
2054 WARN_ON(lowest_level && ins_len > 0);
2055 WARN_ON(p->nodes[0] != NULL);
2056 BUG_ON(!cow && ins_len);
2057
2058 /*
2059 * For now only allow nowait for read only operations. There's no
2060 * strict reason why we can't, we just only need it for reads so it's
2061 * only implemented for reads.
2062 */
2063 ASSERT(!p->nowait || !cow);
2064
2065 if (ins_len < 0) {
2066 lowest_unlock = 2;
2067
2068 /* when we are removing items, we might have to go up to level
2069 * two as we update tree pointers Make sure we keep write
2070 * for those levels as well
2071 */
2072 write_lock_level = 2;
2073 } else if (ins_len > 0) {
2074 /*
2075 * for inserting items, make sure we have a write lock on
2076 * level 1 so we can update keys
2077 */
2078 write_lock_level = 1;
2079 }
2080
2081 if (!cow)
2082 write_lock_level = -1;
2083
2084 if (cow && (p->keep_locks || p->lowest_level))
2085 write_lock_level = BTRFS_MAX_LEVEL;
2086
2087 min_write_lock_level = write_lock_level;
2088
2089 if (p->need_commit_sem) {
2090 ASSERT(p->search_commit_root);
2091 if (p->nowait) {
2092 if (!down_read_trylock(&fs_info->commit_root_sem))
2093 return -EAGAIN;
2094 } else {
2095 down_read(&fs_info->commit_root_sem);
2096 }
2097 }
2098
2099again:
2100 prev_cmp = -1;
2101 b = btrfs_search_slot_get_root(root, p, write_lock_level);
2102 if (IS_ERR(b)) {
2103 ret = PTR_ERR(b);
2104 goto done;
2105 }
2106
2107 while (b) {
2108 int dec = 0;
2109
2110 level = btrfs_header_level(b);
2111
2112 if (cow) {
2113 bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2114
2115 /*
2116 * if we don't really need to cow this block
2117 * then we don't want to set the path blocking,
2118 * so we test it here
2119 */
2120 if (!should_cow_block(trans, root, b))
2121 goto cow_done;
2122
2123 /*
2124 * must have write locks on this node and the
2125 * parent
2126 */
2127 if (level > write_lock_level ||
2128 (level + 1 > write_lock_level &&
2129 level + 1 < BTRFS_MAX_LEVEL &&
2130 p->nodes[level + 1])) {
2131 write_lock_level = level + 1;
2132 btrfs_release_path(p);
2133 goto again;
2134 }
2135
2136 if (last_level)
2137 err = btrfs_cow_block(trans, root, b, NULL, 0,
2138 &b,
2139 BTRFS_NESTING_COW);
2140 else
2141 err = btrfs_cow_block(trans, root, b,
2142 p->nodes[level + 1],
2143 p->slots[level + 1], &b,
2144 BTRFS_NESTING_COW);
2145 if (err) {
2146 ret = err;
2147 goto done;
2148 }
2149 }
2150cow_done:
2151 p->nodes[level] = b;
2152
2153 /*
2154 * we have a lock on b and as long as we aren't changing
2155 * the tree, there is no way to for the items in b to change.
2156 * It is safe to drop the lock on our parent before we
2157 * go through the expensive btree search on b.
2158 *
2159 * If we're inserting or deleting (ins_len != 0), then we might
2160 * be changing slot zero, which may require changing the parent.
2161 * So, we can't drop the lock until after we know which slot
2162 * we're operating on.
2163 */
2164 if (!ins_len && !p->keep_locks) {
2165 int u = level + 1;
2166
2167 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2168 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2169 p->locks[u] = 0;
2170 }
2171 }
2172
2173 if (level == 0) {
2174 if (ins_len > 0)
2175 ASSERT(write_lock_level >= 1);
2176
2177 ret = search_leaf(trans, root, key, p, ins_len, prev_cmp);
2178 if (!p->search_for_split)
2179 unlock_up(p, level, lowest_unlock,
2180 min_write_lock_level, NULL);
2181 goto done;
2182 }
2183
2184 ret = search_for_key_slot(b, 0, key, prev_cmp, &slot);
2185 if (ret < 0)
2186 goto done;
2187 prev_cmp = ret;
2188
2189 if (ret && slot > 0) {
2190 dec = 1;
2191 slot--;
2192 }
2193 p->slots[level] = slot;
2194 err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
2195 &write_lock_level);
2196 if (err == -EAGAIN)
2197 goto again;
2198 if (err) {
2199 ret = err;
2200 goto done;
2201 }
2202 b = p->nodes[level];
2203 slot = p->slots[level];
2204
2205 /*
2206 * Slot 0 is special, if we change the key we have to update
2207 * the parent pointer which means we must have a write lock on
2208 * the parent
2209 */
2210 if (slot == 0 && ins_len && write_lock_level < level + 1) {
2211 write_lock_level = level + 1;
2212 btrfs_release_path(p);
2213 goto again;
2214 }
2215
2216 unlock_up(p, level, lowest_unlock, min_write_lock_level,
2217 &write_lock_level);
2218
2219 if (level == lowest_level) {
2220 if (dec)
2221 p->slots[level]++;
2222 goto done;
2223 }
2224
2225 err = read_block_for_search(root, p, &b, level, slot, key);
2226 if (err == -EAGAIN)
2227 goto again;
2228 if (err) {
2229 ret = err;
2230 goto done;
2231 }
2232
2233 if (!p->skip_locking) {
2234 level = btrfs_header_level(b);
2235
2236 btrfs_maybe_reset_lockdep_class(root, b);
2237
2238 if (level <= write_lock_level) {
2239 btrfs_tree_lock(b);
2240 p->locks[level] = BTRFS_WRITE_LOCK;
2241 } else {
2242 if (p->nowait) {
2243 if (!btrfs_try_tree_read_lock(b)) {
2244 free_extent_buffer(b);
2245 ret = -EAGAIN;
2246 goto done;
2247 }
2248 } else {
2249 btrfs_tree_read_lock(b);
2250 }
2251 p->locks[level] = BTRFS_READ_LOCK;
2252 }
2253 p->nodes[level] = b;
2254 }
2255 }
2256 ret = 1;
2257done:
2258 if (ret < 0 && !p->skip_release_on_error)
2259 btrfs_release_path(p);
2260
2261 if (p->need_commit_sem) {
2262 int ret2;
2263
2264 ret2 = finish_need_commit_sem_search(p);
2265 up_read(&fs_info->commit_root_sem);
2266 if (ret2)
2267 ret = ret2;
2268 }
2269
2270 return ret;
2271}
2272ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO);
2273
2274/*
2275 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2276 * current state of the tree together with the operations recorded in the tree
2277 * modification log to search for the key in a previous version of this tree, as
2278 * denoted by the time_seq parameter.
2279 *
2280 * Naturally, there is no support for insert, delete or cow operations.
2281 *
2282 * The resulting path and return value will be set up as if we called
2283 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2284 */
2285int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2286 struct btrfs_path *p, u64 time_seq)
2287{
2288 struct btrfs_fs_info *fs_info = root->fs_info;
2289 struct extent_buffer *b;
2290 int slot;
2291 int ret;
2292 int err;
2293 int level;
2294 int lowest_unlock = 1;
2295 u8 lowest_level = 0;
2296
2297 lowest_level = p->lowest_level;
2298 WARN_ON(p->nodes[0] != NULL);
2299 ASSERT(!p->nowait);
2300
2301 if (p->search_commit_root) {
2302 BUG_ON(time_seq);
2303 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2304 }
2305
2306again:
2307 b = btrfs_get_old_root(root, time_seq);
2308 if (!b) {
2309 ret = -EIO;
2310 goto done;
2311 }
2312 level = btrfs_header_level(b);
2313 p->locks[level] = BTRFS_READ_LOCK;
2314
2315 while (b) {
2316 int dec = 0;
2317
2318 level = btrfs_header_level(b);
2319 p->nodes[level] = b;
2320
2321 /*
2322 * we have a lock on b and as long as we aren't changing
2323 * the tree, there is no way to for the items in b to change.
2324 * It is safe to drop the lock on our parent before we
2325 * go through the expensive btree search on b.
2326 */
2327 btrfs_unlock_up_safe(p, level + 1);
2328
2329 ret = btrfs_bin_search(b, key, &slot);
2330 if (ret < 0)
2331 goto done;
2332
2333 if (level == 0) {
2334 p->slots[level] = slot;
2335 unlock_up(p, level, lowest_unlock, 0, NULL);
2336 goto done;
2337 }
2338
2339 if (ret && slot > 0) {
2340 dec = 1;
2341 slot--;
2342 }
2343 p->slots[level] = slot;
2344 unlock_up(p, level, lowest_unlock, 0, NULL);
2345
2346 if (level == lowest_level) {
2347 if (dec)
2348 p->slots[level]++;
2349 goto done;
2350 }
2351
2352 err = read_block_for_search(root, p, &b, level, slot, key);
2353 if (err == -EAGAIN)
2354 goto again;
2355 if (err) {
2356 ret = err;
2357 goto done;
2358 }
2359
2360 level = btrfs_header_level(b);
2361 btrfs_tree_read_lock(b);
2362 b = btrfs_tree_mod_log_rewind(fs_info, p, b, time_seq);
2363 if (!b) {
2364 ret = -ENOMEM;
2365 goto done;
2366 }
2367 p->locks[level] = BTRFS_READ_LOCK;
2368 p->nodes[level] = b;
2369 }
2370 ret = 1;
2371done:
2372 if (ret < 0)
2373 btrfs_release_path(p);
2374
2375 return ret;
2376}
2377
2378/*
2379 * helper to use instead of search slot if no exact match is needed but
2380 * instead the next or previous item should be returned.
2381 * When find_higher is true, the next higher item is returned, the next lower
2382 * otherwise.
2383 * When return_any and find_higher are both true, and no higher item is found,
2384 * return the next lower instead.
2385 * When return_any is true and find_higher is false, and no lower item is found,
2386 * return the next higher instead.
2387 * It returns 0 if any item is found, 1 if none is found (tree empty), and
2388 * < 0 on error
2389 */
2390int btrfs_search_slot_for_read(struct btrfs_root *root,
2391 const struct btrfs_key *key,
2392 struct btrfs_path *p, int find_higher,
2393 int return_any)
2394{
2395 int ret;
2396 struct extent_buffer *leaf;
2397
2398again:
2399 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
2400 if (ret <= 0)
2401 return ret;
2402 /*
2403 * a return value of 1 means the path is at the position where the
2404 * item should be inserted. Normally this is the next bigger item,
2405 * but in case the previous item is the last in a leaf, path points
2406 * to the first free slot in the previous leaf, i.e. at an invalid
2407 * item.
2408 */
2409 leaf = p->nodes[0];
2410
2411 if (find_higher) {
2412 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
2413 ret = btrfs_next_leaf(root, p);
2414 if (ret <= 0)
2415 return ret;
2416 if (!return_any)
2417 return 1;
2418 /*
2419 * no higher item found, return the next
2420 * lower instead
2421 */
2422 return_any = 0;
2423 find_higher = 0;
2424 btrfs_release_path(p);
2425 goto again;
2426 }
2427 } else {
2428 if (p->slots[0] == 0) {
2429 ret = btrfs_prev_leaf(root, p);
2430 if (ret < 0)
2431 return ret;
2432 if (!ret) {
2433 leaf = p->nodes[0];
2434 if (p->slots[0] == btrfs_header_nritems(leaf))
2435 p->slots[0]--;
2436 return 0;
2437 }
2438 if (!return_any)
2439 return 1;
2440 /*
2441 * no lower item found, return the next
2442 * higher instead
2443 */
2444 return_any = 0;
2445 find_higher = 1;
2446 btrfs_release_path(p);
2447 goto again;
2448 } else {
2449 --p->slots[0];
2450 }
2451 }
2452 return 0;
2453}
2454
2455/*
2456 * Execute search and call btrfs_previous_item to traverse backwards if the item
2457 * was not found.
2458 *
2459 * Return 0 if found, 1 if not found and < 0 if error.
2460 */
2461int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key,
2462 struct btrfs_path *path)
2463{
2464 int ret;
2465
2466 ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
2467 if (ret > 0)
2468 ret = btrfs_previous_item(root, path, key->objectid, key->type);
2469
2470 if (ret == 0)
2471 btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
2472
2473 return ret;
2474}
2475
2476/*
2477 * Search for a valid slot for the given path.
2478 *
2479 * @root: The root node of the tree.
2480 * @key: Will contain a valid item if found.
2481 * @path: The starting point to validate the slot.
2482 *
2483 * Return: 0 if the item is valid
2484 * 1 if not found
2485 * <0 if error.
2486 */
2487int btrfs_get_next_valid_item(struct btrfs_root *root, struct btrfs_key *key,
2488 struct btrfs_path *path)
2489{
2490 while (1) {
2491 int ret;
2492 const int slot = path->slots[0];
2493 const struct extent_buffer *leaf = path->nodes[0];
2494
2495 /* This is where we start walking the path. */
2496 if (slot >= btrfs_header_nritems(leaf)) {
2497 /*
2498 * If we've reached the last slot in this leaf we need
2499 * to go to the next leaf and reset the path.
2500 */
2501 ret = btrfs_next_leaf(root, path);
2502 if (ret)
2503 return ret;
2504 continue;
2505 }
2506 /* Store the found, valid item in @key. */
2507 btrfs_item_key_to_cpu(leaf, key, slot);
2508 break;
2509 }
2510 return 0;
2511}
2512
2513/*
2514 * adjust the pointers going up the tree, starting at level
2515 * making sure the right key of each node is points to 'key'.
2516 * This is used after shifting pointers to the left, so it stops
2517 * fixing up pointers when a given leaf/node is not in slot 0 of the
2518 * higher levels
2519 *
2520 */
2521static void fixup_low_keys(struct btrfs_path *path,
2522 struct btrfs_disk_key *key, int level)
2523{
2524 int i;
2525 struct extent_buffer *t;
2526 int ret;
2527
2528 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2529 int tslot = path->slots[i];
2530
2531 if (!path->nodes[i])
2532 break;
2533 t = path->nodes[i];
2534 ret = btrfs_tree_mod_log_insert_key(t, tslot,
2535 BTRFS_MOD_LOG_KEY_REPLACE);
2536 BUG_ON(ret < 0);
2537 btrfs_set_node_key(t, key, tslot);
2538 btrfs_mark_buffer_dirty(path->nodes[i]);
2539 if (tslot != 0)
2540 break;
2541 }
2542}
2543
2544/*
2545 * update item key.
2546 *
2547 * This function isn't completely safe. It's the caller's responsibility
2548 * that the new key won't break the order
2549 */
2550void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
2551 struct btrfs_path *path,
2552 const struct btrfs_key *new_key)
2553{
2554 struct btrfs_disk_key disk_key;
2555 struct extent_buffer *eb;
2556 int slot;
2557
2558 eb = path->nodes[0];
2559 slot = path->slots[0];
2560 if (slot > 0) {
2561 btrfs_item_key(eb, &disk_key, slot - 1);
2562 if (unlikely(comp_keys(&disk_key, new_key) >= 0)) {
2563 btrfs_crit(fs_info,
2564 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2565 slot, btrfs_disk_key_objectid(&disk_key),
2566 btrfs_disk_key_type(&disk_key),
2567 btrfs_disk_key_offset(&disk_key),
2568 new_key->objectid, new_key->type,
2569 new_key->offset);
2570 btrfs_print_leaf(eb);
2571 BUG();
2572 }
2573 }
2574 if (slot < btrfs_header_nritems(eb) - 1) {
2575 btrfs_item_key(eb, &disk_key, slot + 1);
2576 if (unlikely(comp_keys(&disk_key, new_key) <= 0)) {
2577 btrfs_crit(fs_info,
2578 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2579 slot, btrfs_disk_key_objectid(&disk_key),
2580 btrfs_disk_key_type(&disk_key),
2581 btrfs_disk_key_offset(&disk_key),
2582 new_key->objectid, new_key->type,
2583 new_key->offset);
2584 btrfs_print_leaf(eb);
2585 BUG();
2586 }
2587 }
2588
2589 btrfs_cpu_key_to_disk(&disk_key, new_key);
2590 btrfs_set_item_key(eb, &disk_key, slot);
2591 btrfs_mark_buffer_dirty(eb);
2592 if (slot == 0)
2593 fixup_low_keys(path, &disk_key, 1);
2594}
2595
2596/*
2597 * Check key order of two sibling extent buffers.
2598 *
2599 * Return true if something is wrong.
2600 * Return false if everything is fine.
2601 *
2602 * Tree-checker only works inside one tree block, thus the following
2603 * corruption can not be detected by tree-checker:
2604 *
2605 * Leaf @left | Leaf @right
2606 * --------------------------------------------------------------
2607 * | 1 | 2 | 3 | 4 | 5 | f6 | | 7 | 8 |
2608 *
2609 * Key f6 in leaf @left itself is valid, but not valid when the next
2610 * key in leaf @right is 7.
2611 * This can only be checked at tree block merge time.
2612 * And since tree checker has ensured all key order in each tree block
2613 * is correct, we only need to bother the last key of @left and the first
2614 * key of @right.
2615 */
2616static bool check_sibling_keys(struct extent_buffer *left,
2617 struct extent_buffer *right)
2618{
2619 struct btrfs_key left_last;
2620 struct btrfs_key right_first;
2621 int level = btrfs_header_level(left);
2622 int nr_left = btrfs_header_nritems(left);
2623 int nr_right = btrfs_header_nritems(right);
2624
2625 /* No key to check in one of the tree blocks */
2626 if (!nr_left || !nr_right)
2627 return false;
2628
2629 if (level) {
2630 btrfs_node_key_to_cpu(left, &left_last, nr_left - 1);
2631 btrfs_node_key_to_cpu(right, &right_first, 0);
2632 } else {
2633 btrfs_item_key_to_cpu(left, &left_last, nr_left - 1);
2634 btrfs_item_key_to_cpu(right, &right_first, 0);
2635 }
2636
2637 if (btrfs_comp_cpu_keys(&left_last, &right_first) >= 0) {
2638 btrfs_crit(left->fs_info,
2639"bad key order, sibling blocks, left last (%llu %u %llu) right first (%llu %u %llu)",
2640 left_last.objectid, left_last.type,
2641 left_last.offset, right_first.objectid,
2642 right_first.type, right_first.offset);
2643 return true;
2644 }
2645 return false;
2646}
2647
2648/*
2649 * try to push data from one node into the next node left in the
2650 * tree.
2651 *
2652 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2653 * error, and > 0 if there was no room in the left hand block.
2654 */
2655static int push_node_left(struct btrfs_trans_handle *trans,
2656 struct extent_buffer *dst,
2657 struct extent_buffer *src, int empty)
2658{
2659 struct btrfs_fs_info *fs_info = trans->fs_info;
2660 int push_items = 0;
2661 int src_nritems;
2662 int dst_nritems;
2663 int ret = 0;
2664
2665 src_nritems = btrfs_header_nritems(src);
2666 dst_nritems = btrfs_header_nritems(dst);
2667 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2668 WARN_ON(btrfs_header_generation(src) != trans->transid);
2669 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2670
2671 if (!empty && src_nritems <= 8)
2672 return 1;
2673
2674 if (push_items <= 0)
2675 return 1;
2676
2677 if (empty) {
2678 push_items = min(src_nritems, push_items);
2679 if (push_items < src_nritems) {
2680 /* leave at least 8 pointers in the node if
2681 * we aren't going to empty it
2682 */
2683 if (src_nritems - push_items < 8) {
2684 if (push_items <= 8)
2685 return 1;
2686 push_items -= 8;
2687 }
2688 }
2689 } else
2690 push_items = min(src_nritems - 8, push_items);
2691
2692 /* dst is the left eb, src is the middle eb */
2693 if (check_sibling_keys(dst, src)) {
2694 ret = -EUCLEAN;
2695 btrfs_abort_transaction(trans, ret);
2696 return ret;
2697 }
2698 ret = btrfs_tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
2699 if (ret) {
2700 btrfs_abort_transaction(trans, ret);
2701 return ret;
2702 }
2703 copy_extent_buffer(dst, src,
2704 btrfs_node_key_ptr_offset(dst, dst_nritems),
2705 btrfs_node_key_ptr_offset(src, 0),
2706 push_items * sizeof(struct btrfs_key_ptr));
2707
2708 if (push_items < src_nritems) {
2709 /*
2710 * Don't call btrfs_tree_mod_log_insert_move() here, key removal
2711 * was already fully logged by btrfs_tree_mod_log_eb_copy() above.
2712 */
2713 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(src, 0),
2714 btrfs_node_key_ptr_offset(src, push_items),
2715 (src_nritems - push_items) *
2716 sizeof(struct btrfs_key_ptr));
2717 }
2718 btrfs_set_header_nritems(src, src_nritems - push_items);
2719 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2720 btrfs_mark_buffer_dirty(src);
2721 btrfs_mark_buffer_dirty(dst);
2722
2723 return ret;
2724}
2725
2726/*
2727 * try to push data from one node into the next node right in the
2728 * tree.
2729 *
2730 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
2731 * error, and > 0 if there was no room in the right hand block.
2732 *
2733 * this will only push up to 1/2 the contents of the left node over
2734 */
2735static int balance_node_right(struct btrfs_trans_handle *trans,
2736 struct extent_buffer *dst,
2737 struct extent_buffer *src)
2738{
2739 struct btrfs_fs_info *fs_info = trans->fs_info;
2740 int push_items = 0;
2741 int max_push;
2742 int src_nritems;
2743 int dst_nritems;
2744 int ret = 0;
2745
2746 WARN_ON(btrfs_header_generation(src) != trans->transid);
2747 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2748
2749 src_nritems = btrfs_header_nritems(src);
2750 dst_nritems = btrfs_header_nritems(dst);
2751 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2752 if (push_items <= 0)
2753 return 1;
2754
2755 if (src_nritems < 4)
2756 return 1;
2757
2758 max_push = src_nritems / 2 + 1;
2759 /* don't try to empty the node */
2760 if (max_push >= src_nritems)
2761 return 1;
2762
2763 if (max_push < push_items)
2764 push_items = max_push;
2765
2766 /* dst is the right eb, src is the middle eb */
2767 if (check_sibling_keys(src, dst)) {
2768 ret = -EUCLEAN;
2769 btrfs_abort_transaction(trans, ret);
2770 return ret;
2771 }
2772 ret = btrfs_tree_mod_log_insert_move(dst, push_items, 0, dst_nritems);
2773 BUG_ON(ret < 0);
2774 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(dst, push_items),
2775 btrfs_node_key_ptr_offset(dst, 0),
2776 (dst_nritems) *
2777 sizeof(struct btrfs_key_ptr));
2778
2779 ret = btrfs_tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
2780 push_items);
2781 if (ret) {
2782 btrfs_abort_transaction(trans, ret);
2783 return ret;
2784 }
2785 copy_extent_buffer(dst, src,
2786 btrfs_node_key_ptr_offset(dst, 0),
2787 btrfs_node_key_ptr_offset(src, src_nritems - push_items),
2788 push_items * sizeof(struct btrfs_key_ptr));
2789
2790 btrfs_set_header_nritems(src, src_nritems - push_items);
2791 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2792
2793 btrfs_mark_buffer_dirty(src);
2794 btrfs_mark_buffer_dirty(dst);
2795
2796 return ret;
2797}
2798
2799/*
2800 * helper function to insert a new root level in the tree.
2801 * A new node is allocated, and a single item is inserted to
2802 * point to the existing root
2803 *
2804 * returns zero on success or < 0 on failure.
2805 */
2806static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2807 struct btrfs_root *root,
2808 struct btrfs_path *path, int level)
2809{
2810 struct btrfs_fs_info *fs_info = root->fs_info;
2811 u64 lower_gen;
2812 struct extent_buffer *lower;
2813 struct extent_buffer *c;
2814 struct extent_buffer *old;
2815 struct btrfs_disk_key lower_key;
2816 int ret;
2817
2818 BUG_ON(path->nodes[level]);
2819 BUG_ON(path->nodes[level-1] != root->node);
2820
2821 lower = path->nodes[level-1];
2822 if (level == 1)
2823 btrfs_item_key(lower, &lower_key, 0);
2824 else
2825 btrfs_node_key(lower, &lower_key, 0);
2826
2827 c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
2828 &lower_key, level, root->node->start, 0,
2829 BTRFS_NESTING_NEW_ROOT);
2830 if (IS_ERR(c))
2831 return PTR_ERR(c);
2832
2833 root_add_used(root, fs_info->nodesize);
2834
2835 btrfs_set_header_nritems(c, 1);
2836 btrfs_set_node_key(c, &lower_key, 0);
2837 btrfs_set_node_blockptr(c, 0, lower->start);
2838 lower_gen = btrfs_header_generation(lower);
2839 WARN_ON(lower_gen != trans->transid);
2840
2841 btrfs_set_node_ptr_generation(c, 0, lower_gen);
2842
2843 btrfs_mark_buffer_dirty(c);
2844
2845 old = root->node;
2846 ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
2847 BUG_ON(ret < 0);
2848 rcu_assign_pointer(root->node, c);
2849
2850 /* the super has an extra ref to root->node */
2851 free_extent_buffer(old);
2852
2853 add_root_to_dirty_list(root);
2854 atomic_inc(&c->refs);
2855 path->nodes[level] = c;
2856 path->locks[level] = BTRFS_WRITE_LOCK;
2857 path->slots[level] = 0;
2858 return 0;
2859}
2860
2861/*
2862 * worker function to insert a single pointer in a node.
2863 * the node should have enough room for the pointer already
2864 *
2865 * slot and level indicate where you want the key to go, and
2866 * blocknr is the block the key points to.
2867 */
2868static void insert_ptr(struct btrfs_trans_handle *trans,
2869 struct btrfs_path *path,
2870 struct btrfs_disk_key *key, u64 bytenr,
2871 int slot, int level)
2872{
2873 struct extent_buffer *lower;
2874 int nritems;
2875 int ret;
2876
2877 BUG_ON(!path->nodes[level]);
2878 btrfs_assert_tree_write_locked(path->nodes[level]);
2879 lower = path->nodes[level];
2880 nritems = btrfs_header_nritems(lower);
2881 BUG_ON(slot > nritems);
2882 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
2883 if (slot != nritems) {
2884 if (level) {
2885 ret = btrfs_tree_mod_log_insert_move(lower, slot + 1,
2886 slot, nritems - slot);
2887 BUG_ON(ret < 0);
2888 }
2889 memmove_extent_buffer(lower,
2890 btrfs_node_key_ptr_offset(lower, slot + 1),
2891 btrfs_node_key_ptr_offset(lower, slot),
2892 (nritems - slot) * sizeof(struct btrfs_key_ptr));
2893 }
2894 if (level) {
2895 ret = btrfs_tree_mod_log_insert_key(lower, slot,
2896 BTRFS_MOD_LOG_KEY_ADD);
2897 BUG_ON(ret < 0);
2898 }
2899 btrfs_set_node_key(lower, key, slot);
2900 btrfs_set_node_blockptr(lower, slot, bytenr);
2901 WARN_ON(trans->transid == 0);
2902 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
2903 btrfs_set_header_nritems(lower, nritems + 1);
2904 btrfs_mark_buffer_dirty(lower);
2905}
2906
2907/*
2908 * split the node at the specified level in path in two.
2909 * The path is corrected to point to the appropriate node after the split
2910 *
2911 * Before splitting this tries to make some room in the node by pushing
2912 * left and right, if either one works, it returns right away.
2913 *
2914 * returns 0 on success and < 0 on failure
2915 */
2916static noinline int split_node(struct btrfs_trans_handle *trans,
2917 struct btrfs_root *root,
2918 struct btrfs_path *path, int level)
2919{
2920 struct btrfs_fs_info *fs_info = root->fs_info;
2921 struct extent_buffer *c;
2922 struct extent_buffer *split;
2923 struct btrfs_disk_key disk_key;
2924 int mid;
2925 int ret;
2926 u32 c_nritems;
2927
2928 c = path->nodes[level];
2929 WARN_ON(btrfs_header_generation(c) != trans->transid);
2930 if (c == root->node) {
2931 /*
2932 * trying to split the root, lets make a new one
2933 *
2934 * tree mod log: We don't log_removal old root in
2935 * insert_new_root, because that root buffer will be kept as a
2936 * normal node. We are going to log removal of half of the
2937 * elements below with btrfs_tree_mod_log_eb_copy(). We're
2938 * holding a tree lock on the buffer, which is why we cannot
2939 * race with other tree_mod_log users.
2940 */
2941 ret = insert_new_root(trans, root, path, level + 1);
2942 if (ret)
2943 return ret;
2944 } else {
2945 ret = push_nodes_for_insert(trans, root, path, level);
2946 c = path->nodes[level];
2947 if (!ret && btrfs_header_nritems(c) <
2948 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
2949 return 0;
2950 if (ret < 0)
2951 return ret;
2952 }
2953
2954 c_nritems = btrfs_header_nritems(c);
2955 mid = (c_nritems + 1) / 2;
2956 btrfs_node_key(c, &disk_key, mid);
2957
2958 split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
2959 &disk_key, level, c->start, 0,
2960 BTRFS_NESTING_SPLIT);
2961 if (IS_ERR(split))
2962 return PTR_ERR(split);
2963
2964 root_add_used(root, fs_info->nodesize);
2965 ASSERT(btrfs_header_level(c) == level);
2966
2967 ret = btrfs_tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
2968 if (ret) {
2969 btrfs_abort_transaction(trans, ret);
2970 return ret;
2971 }
2972 copy_extent_buffer(split, c,
2973 btrfs_node_key_ptr_offset(split, 0),
2974 btrfs_node_key_ptr_offset(c, mid),
2975 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
2976 btrfs_set_header_nritems(split, c_nritems - mid);
2977 btrfs_set_header_nritems(c, mid);
2978
2979 btrfs_mark_buffer_dirty(c);
2980 btrfs_mark_buffer_dirty(split);
2981
2982 insert_ptr(trans, path, &disk_key, split->start,
2983 path->slots[level + 1] + 1, level + 1);
2984
2985 if (path->slots[level] >= mid) {
2986 path->slots[level] -= mid;
2987 btrfs_tree_unlock(c);
2988 free_extent_buffer(c);
2989 path->nodes[level] = split;
2990 path->slots[level + 1] += 1;
2991 } else {
2992 btrfs_tree_unlock(split);
2993 free_extent_buffer(split);
2994 }
2995 return 0;
2996}
2997
2998/*
2999 * how many bytes are required to store the items in a leaf. start
3000 * and nr indicate which items in the leaf to check. This totals up the
3001 * space used both by the item structs and the item data
3002 */
3003static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3004{
3005 int data_len;
3006 int nritems = btrfs_header_nritems(l);
3007 int end = min(nritems, start + nr) - 1;
3008
3009 if (!nr)
3010 return 0;
3011 data_len = btrfs_item_offset(l, start) + btrfs_item_size(l, start);
3012 data_len = data_len - btrfs_item_offset(l, end);
3013 data_len += sizeof(struct btrfs_item) * nr;
3014 WARN_ON(data_len < 0);
3015 return data_len;
3016}
3017
3018/*
3019 * The space between the end of the leaf items and
3020 * the start of the leaf data. IOW, how much room
3021 * the leaf has left for both items and data
3022 */
3023noinline int btrfs_leaf_free_space(struct extent_buffer *leaf)
3024{
3025 struct btrfs_fs_info *fs_info = leaf->fs_info;
3026 int nritems = btrfs_header_nritems(leaf);
3027 int ret;
3028
3029 ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
3030 if (ret < 0) {
3031 btrfs_crit(fs_info,
3032 "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3033 ret,
3034 (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
3035 leaf_space_used(leaf, 0, nritems), nritems);
3036 }
3037 return ret;
3038}
3039
3040/*
3041 * min slot controls the lowest index we're willing to push to the
3042 * right. We'll push up to and including min_slot, but no lower
3043 */
3044static noinline int __push_leaf_right(struct btrfs_path *path,
3045 int data_size, int empty,
3046 struct extent_buffer *right,
3047 int free_space, u32 left_nritems,
3048 u32 min_slot)
3049{
3050 struct btrfs_fs_info *fs_info = right->fs_info;
3051 struct extent_buffer *left = path->nodes[0];
3052 struct extent_buffer *upper = path->nodes[1];
3053 struct btrfs_map_token token;
3054 struct btrfs_disk_key disk_key;
3055 int slot;
3056 u32 i;
3057 int push_space = 0;
3058 int push_items = 0;
3059 u32 nr;
3060 u32 right_nritems;
3061 u32 data_end;
3062 u32 this_item_size;
3063
3064 if (empty)
3065 nr = 0;
3066 else
3067 nr = max_t(u32, 1, min_slot);
3068
3069 if (path->slots[0] >= left_nritems)
3070 push_space += data_size;
3071
3072 slot = path->slots[1];
3073 i = left_nritems - 1;
3074 while (i >= nr) {
3075 if (!empty && push_items > 0) {
3076 if (path->slots[0] > i)
3077 break;
3078 if (path->slots[0] == i) {
3079 int space = btrfs_leaf_free_space(left);
3080
3081 if (space + push_space * 2 > free_space)
3082 break;
3083 }
3084 }
3085
3086 if (path->slots[0] == i)
3087 push_space += data_size;
3088
3089 this_item_size = btrfs_item_size(left, i);
3090 if (this_item_size + sizeof(struct btrfs_item) +
3091 push_space > free_space)
3092 break;
3093
3094 push_items++;
3095 push_space += this_item_size + sizeof(struct btrfs_item);
3096 if (i == 0)
3097 break;
3098 i--;
3099 }
3100
3101 if (push_items == 0)
3102 goto out_unlock;
3103
3104 WARN_ON(!empty && push_items == left_nritems);
3105
3106 /* push left to right */
3107 right_nritems = btrfs_header_nritems(right);
3108
3109 push_space = btrfs_item_data_end(left, left_nritems - push_items);
3110 push_space -= leaf_data_end(left);
3111
3112 /* make room in the right data area */
3113 data_end = leaf_data_end(right);
3114 memmove_leaf_data(right, data_end - push_space, data_end,
3115 BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
3116
3117 /* copy from the left data area */
3118 copy_leaf_data(right, left, BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3119 leaf_data_end(left), push_space);
3120
3121 memmove_leaf_items(right, push_items, 0, right_nritems);
3122
3123 /* copy the items from left to right */
3124 copy_leaf_items(right, left, 0, left_nritems - push_items, push_items);
3125
3126 /* update the item pointers */
3127 btrfs_init_map_token(&token, right);
3128 right_nritems += push_items;
3129 btrfs_set_header_nritems(right, right_nritems);
3130 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3131 for (i = 0; i < right_nritems; i++) {
3132 push_space -= btrfs_token_item_size(&token, i);
3133 btrfs_set_token_item_offset(&token, i, push_space);
3134 }
3135
3136 left_nritems -= push_items;
3137 btrfs_set_header_nritems(left, left_nritems);
3138
3139 if (left_nritems)
3140 btrfs_mark_buffer_dirty(left);
3141 else
3142 btrfs_clean_tree_block(left);
3143
3144 btrfs_mark_buffer_dirty(right);
3145
3146 btrfs_item_key(right, &disk_key, 0);
3147 btrfs_set_node_key(upper, &disk_key, slot + 1);
3148 btrfs_mark_buffer_dirty(upper);
3149
3150 /* then fixup the leaf pointer in the path */
3151 if (path->slots[0] >= left_nritems) {
3152 path->slots[0] -= left_nritems;
3153 if (btrfs_header_nritems(path->nodes[0]) == 0)
3154 btrfs_clean_tree_block(path->nodes[0]);
3155 btrfs_tree_unlock(path->nodes[0]);
3156 free_extent_buffer(path->nodes[0]);
3157 path->nodes[0] = right;
3158 path->slots[1] += 1;
3159 } else {
3160 btrfs_tree_unlock(right);
3161 free_extent_buffer(right);
3162 }
3163 return 0;
3164
3165out_unlock:
3166 btrfs_tree_unlock(right);
3167 free_extent_buffer(right);
3168 return 1;
3169}
3170
3171/*
3172 * push some data in the path leaf to the right, trying to free up at
3173 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3174 *
3175 * returns 1 if the push failed because the other node didn't have enough
3176 * room, 0 if everything worked out and < 0 if there were major errors.
3177 *
3178 * this will push starting from min_slot to the end of the leaf. It won't
3179 * push any slot lower than min_slot
3180 */
3181static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3182 *root, struct btrfs_path *path,
3183 int min_data_size, int data_size,
3184 int empty, u32 min_slot)
3185{
3186 struct extent_buffer *left = path->nodes[0];
3187 struct extent_buffer *right;
3188 struct extent_buffer *upper;
3189 int slot;
3190 int free_space;
3191 u32 left_nritems;
3192 int ret;
3193
3194 if (!path->nodes[1])
3195 return 1;
3196
3197 slot = path->slots[1];
3198 upper = path->nodes[1];
3199 if (slot >= btrfs_header_nritems(upper) - 1)
3200 return 1;
3201
3202 btrfs_assert_tree_write_locked(path->nodes[1]);
3203
3204 right = btrfs_read_node_slot(upper, slot + 1);
3205 /*
3206 * slot + 1 is not valid or we fail to read the right node,
3207 * no big deal, just return.
3208 */
3209 if (IS_ERR(right))
3210 return 1;
3211
3212 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
3213
3214 free_space = btrfs_leaf_free_space(right);
3215 if (free_space < data_size)
3216 goto out_unlock;
3217
3218 ret = btrfs_cow_block(trans, root, right, upper,
3219 slot + 1, &right, BTRFS_NESTING_RIGHT_COW);
3220 if (ret)
3221 goto out_unlock;
3222
3223 left_nritems = btrfs_header_nritems(left);
3224 if (left_nritems == 0)
3225 goto out_unlock;
3226
3227 if (check_sibling_keys(left, right)) {
3228 ret = -EUCLEAN;
3229 btrfs_tree_unlock(right);
3230 free_extent_buffer(right);
3231 return ret;
3232 }
3233 if (path->slots[0] == left_nritems && !empty) {
3234 /* Key greater than all keys in the leaf, right neighbor has
3235 * enough room for it and we're not emptying our leaf to delete
3236 * it, therefore use right neighbor to insert the new item and
3237 * no need to touch/dirty our left leaf. */
3238 btrfs_tree_unlock(left);
3239 free_extent_buffer(left);
3240 path->nodes[0] = right;
3241 path->slots[0] = 0;
3242 path->slots[1]++;
3243 return 0;
3244 }
3245
3246 return __push_leaf_right(path, min_data_size, empty,
3247 right, free_space, left_nritems, min_slot);
3248out_unlock:
3249 btrfs_tree_unlock(right);
3250 free_extent_buffer(right);
3251 return 1;
3252}
3253
3254/*
3255 * push some data in the path leaf to the left, trying to free up at
3256 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3257 *
3258 * max_slot can put a limit on how far into the leaf we'll push items. The
3259 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3260 * items
3261 */
3262static noinline int __push_leaf_left(struct btrfs_path *path, int data_size,
3263 int empty, struct extent_buffer *left,
3264 int free_space, u32 right_nritems,
3265 u32 max_slot)
3266{
3267 struct btrfs_fs_info *fs_info = left->fs_info;
3268 struct btrfs_disk_key disk_key;
3269 struct extent_buffer *right = path->nodes[0];
3270 int i;
3271 int push_space = 0;
3272 int push_items = 0;
3273 u32 old_left_nritems;
3274 u32 nr;
3275 int ret = 0;
3276 u32 this_item_size;
3277 u32 old_left_item_size;
3278 struct btrfs_map_token token;
3279
3280 if (empty)
3281 nr = min(right_nritems, max_slot);
3282 else
3283 nr = min(right_nritems - 1, max_slot);
3284
3285 for (i = 0; i < nr; i++) {
3286 if (!empty && push_items > 0) {
3287 if (path->slots[0] < i)
3288 break;
3289 if (path->slots[0] == i) {
3290 int space = btrfs_leaf_free_space(right);
3291
3292 if (space + push_space * 2 > free_space)
3293 break;
3294 }
3295 }
3296
3297 if (path->slots[0] == i)
3298 push_space += data_size;
3299
3300 this_item_size = btrfs_item_size(right, i);
3301 if (this_item_size + sizeof(struct btrfs_item) + push_space >
3302 free_space)
3303 break;
3304
3305 push_items++;
3306 push_space += this_item_size + sizeof(struct btrfs_item);
3307 }
3308
3309 if (push_items == 0) {
3310 ret = 1;
3311 goto out;
3312 }
3313 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3314
3315 /* push data from right to left */
3316 copy_leaf_items(left, right, btrfs_header_nritems(left), 0, push_items);
3317
3318 push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3319 btrfs_item_offset(right, push_items - 1);
3320
3321 copy_leaf_data(left, right, leaf_data_end(left) - push_space,
3322 btrfs_item_offset(right, push_items - 1), push_space);
3323 old_left_nritems = btrfs_header_nritems(left);
3324 BUG_ON(old_left_nritems <= 0);
3325
3326 btrfs_init_map_token(&token, left);
3327 old_left_item_size = btrfs_item_offset(left, old_left_nritems - 1);
3328 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3329 u32 ioff;
3330
3331 ioff = btrfs_token_item_offset(&token, i);
3332 btrfs_set_token_item_offset(&token, i,
3333 ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size));
3334 }
3335 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3336
3337 /* fixup right node */
3338 if (push_items > right_nritems)
3339 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3340 right_nritems);
3341
3342 if (push_items < right_nritems) {
3343 push_space = btrfs_item_offset(right, push_items - 1) -
3344 leaf_data_end(right);
3345 memmove_leaf_data(right,
3346 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3347 leaf_data_end(right), push_space);
3348
3349 memmove_leaf_items(right, 0, push_items,
3350 btrfs_header_nritems(right) - push_items);
3351 }
3352
3353 btrfs_init_map_token(&token, right);
3354 right_nritems -= push_items;
3355 btrfs_set_header_nritems(right, right_nritems);
3356 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3357 for (i = 0; i < right_nritems; i++) {
3358 push_space = push_space - btrfs_token_item_size(&token, i);
3359 btrfs_set_token_item_offset(&token, i, push_space);
3360 }
3361
3362 btrfs_mark_buffer_dirty(left);
3363 if (right_nritems)
3364 btrfs_mark_buffer_dirty(right);
3365 else
3366 btrfs_clean_tree_block(right);
3367
3368 btrfs_item_key(right, &disk_key, 0);
3369 fixup_low_keys(path, &disk_key, 1);
3370
3371 /* then fixup the leaf pointer in the path */
3372 if (path->slots[0] < push_items) {
3373 path->slots[0] += old_left_nritems;
3374 btrfs_tree_unlock(path->nodes[0]);
3375 free_extent_buffer(path->nodes[0]);
3376 path->nodes[0] = left;
3377 path->slots[1] -= 1;
3378 } else {
3379 btrfs_tree_unlock(left);
3380 free_extent_buffer(left);
3381 path->slots[0] -= push_items;
3382 }
3383 BUG_ON(path->slots[0] < 0);
3384 return ret;
3385out:
3386 btrfs_tree_unlock(left);
3387 free_extent_buffer(left);
3388 return ret;
3389}
3390
3391/*
3392 * push some data in the path leaf to the left, trying to free up at
3393 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3394 *
3395 * max_slot can put a limit on how far into the leaf we'll push items. The
3396 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3397 * items
3398 */
3399static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3400 *root, struct btrfs_path *path, int min_data_size,
3401 int data_size, int empty, u32 max_slot)
3402{
3403 struct extent_buffer *right = path->nodes[0];
3404 struct extent_buffer *left;
3405 int slot;
3406 int free_space;
3407 u32 right_nritems;
3408 int ret = 0;
3409
3410 slot = path->slots[1];
3411 if (slot == 0)
3412 return 1;
3413 if (!path->nodes[1])
3414 return 1;
3415
3416 right_nritems = btrfs_header_nritems(right);
3417 if (right_nritems == 0)
3418 return 1;
3419
3420 btrfs_assert_tree_write_locked(path->nodes[1]);
3421
3422 left = btrfs_read_node_slot(path->nodes[1], slot - 1);
3423 /*
3424 * slot - 1 is not valid or we fail to read the left node,
3425 * no big deal, just return.
3426 */
3427 if (IS_ERR(left))
3428 return 1;
3429
3430 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
3431
3432 free_space = btrfs_leaf_free_space(left);
3433 if (free_space < data_size) {
3434 ret = 1;
3435 goto out;
3436 }
3437
3438 ret = btrfs_cow_block(trans, root, left,
3439 path->nodes[1], slot - 1, &left,
3440 BTRFS_NESTING_LEFT_COW);
3441 if (ret) {
3442 /* we hit -ENOSPC, but it isn't fatal here */
3443 if (ret == -ENOSPC)
3444 ret = 1;
3445 goto out;
3446 }
3447
3448 if (check_sibling_keys(left, right)) {
3449 ret = -EUCLEAN;
3450 goto out;
3451 }
3452 return __push_leaf_left(path, min_data_size,
3453 empty, left, free_space, right_nritems,
3454 max_slot);
3455out:
3456 btrfs_tree_unlock(left);
3457 free_extent_buffer(left);
3458 return ret;
3459}
3460
3461/*
3462 * split the path's leaf in two, making sure there is at least data_size
3463 * available for the resulting leaf level of the path.
3464 */
3465static noinline void copy_for_split(struct btrfs_trans_handle *trans,
3466 struct btrfs_path *path,
3467 struct extent_buffer *l,
3468 struct extent_buffer *right,
3469 int slot, int mid, int nritems)
3470{
3471 struct btrfs_fs_info *fs_info = trans->fs_info;
3472 int data_copy_size;
3473 int rt_data_off;
3474 int i;
3475 struct btrfs_disk_key disk_key;
3476 struct btrfs_map_token token;
3477
3478 nritems = nritems - mid;
3479 btrfs_set_header_nritems(right, nritems);
3480 data_copy_size = btrfs_item_data_end(l, mid) - leaf_data_end(l);
3481
3482 copy_leaf_items(right, l, 0, mid, nritems);
3483
3484 copy_leaf_data(right, l, BTRFS_LEAF_DATA_SIZE(fs_info) - data_copy_size,
3485 leaf_data_end(l), data_copy_size);
3486
3487 rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_data_end(l, mid);
3488
3489 btrfs_init_map_token(&token, right);
3490 for (i = 0; i < nritems; i++) {
3491 u32 ioff;
3492
3493 ioff = btrfs_token_item_offset(&token, i);
3494 btrfs_set_token_item_offset(&token, i, ioff + rt_data_off);
3495 }
3496
3497 btrfs_set_header_nritems(l, mid);
3498 btrfs_item_key(right, &disk_key, 0);
3499 insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
3500
3501 btrfs_mark_buffer_dirty(right);
3502 btrfs_mark_buffer_dirty(l);
3503 BUG_ON(path->slots[0] != slot);
3504
3505 if (mid <= slot) {
3506 btrfs_tree_unlock(path->nodes[0]);
3507 free_extent_buffer(path->nodes[0]);
3508 path->nodes[0] = right;
3509 path->slots[0] -= mid;
3510 path->slots[1] += 1;
3511 } else {
3512 btrfs_tree_unlock(right);
3513 free_extent_buffer(right);
3514 }
3515
3516 BUG_ON(path->slots[0] < 0);
3517}
3518
3519/*
3520 * double splits happen when we need to insert a big item in the middle
3521 * of a leaf. A double split can leave us with 3 mostly empty leaves:
3522 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
3523 * A B C
3524 *
3525 * We avoid this by trying to push the items on either side of our target
3526 * into the adjacent leaves. If all goes well we can avoid the double split
3527 * completely.
3528 */
3529static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
3530 struct btrfs_root *root,
3531 struct btrfs_path *path,
3532 int data_size)
3533{
3534 int ret;
3535 int progress = 0;
3536 int slot;
3537 u32 nritems;
3538 int space_needed = data_size;
3539
3540 slot = path->slots[0];
3541 if (slot < btrfs_header_nritems(path->nodes[0]))
3542 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3543
3544 /*
3545 * try to push all the items after our slot into the
3546 * right leaf
3547 */
3548 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
3549 if (ret < 0)
3550 return ret;
3551
3552 if (ret == 0)
3553 progress++;
3554
3555 nritems = btrfs_header_nritems(path->nodes[0]);
3556 /*
3557 * our goal is to get our slot at the start or end of a leaf. If
3558 * we've done so we're done
3559 */
3560 if (path->slots[0] == 0 || path->slots[0] == nritems)
3561 return 0;
3562
3563 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3564 return 0;
3565
3566 /* try to push all the items before our slot into the next leaf */
3567 slot = path->slots[0];
3568 space_needed = data_size;
3569 if (slot > 0)
3570 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3571 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
3572 if (ret < 0)
3573 return ret;
3574
3575 if (ret == 0)
3576 progress++;
3577
3578 if (progress)
3579 return 0;
3580 return 1;
3581}
3582
3583/*
3584 * split the path's leaf in two, making sure there is at least data_size
3585 * available for the resulting leaf level of the path.
3586 *
3587 * returns 0 if all went well and < 0 on failure.
3588 */
3589static noinline int split_leaf(struct btrfs_trans_handle *trans,
3590 struct btrfs_root *root,
3591 const struct btrfs_key *ins_key,
3592 struct btrfs_path *path, int data_size,
3593 int extend)
3594{
3595 struct btrfs_disk_key disk_key;
3596 struct extent_buffer *l;
3597 u32 nritems;
3598 int mid;
3599 int slot;
3600 struct extent_buffer *right;
3601 struct btrfs_fs_info *fs_info = root->fs_info;
3602 int ret = 0;
3603 int wret;
3604 int split;
3605 int num_doubles = 0;
3606 int tried_avoid_double = 0;
3607
3608 l = path->nodes[0];
3609 slot = path->slots[0];
3610 if (extend && data_size + btrfs_item_size(l, slot) +
3611 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
3612 return -EOVERFLOW;
3613
3614 /* first try to make some room by pushing left and right */
3615 if (data_size && path->nodes[1]) {
3616 int space_needed = data_size;
3617
3618 if (slot < btrfs_header_nritems(l))
3619 space_needed -= btrfs_leaf_free_space(l);
3620
3621 wret = push_leaf_right(trans, root, path, space_needed,
3622 space_needed, 0, 0);
3623 if (wret < 0)
3624 return wret;
3625 if (wret) {
3626 space_needed = data_size;
3627 if (slot > 0)
3628 space_needed -= btrfs_leaf_free_space(l);
3629 wret = push_leaf_left(trans, root, path, space_needed,
3630 space_needed, 0, (u32)-1);
3631 if (wret < 0)
3632 return wret;
3633 }
3634 l = path->nodes[0];
3635
3636 /* did the pushes work? */
3637 if (btrfs_leaf_free_space(l) >= data_size)
3638 return 0;
3639 }
3640
3641 if (!path->nodes[1]) {
3642 ret = insert_new_root(trans, root, path, 1);
3643 if (ret)
3644 return ret;
3645 }
3646again:
3647 split = 1;
3648 l = path->nodes[0];
3649 slot = path->slots[0];
3650 nritems = btrfs_header_nritems(l);
3651 mid = (nritems + 1) / 2;
3652
3653 if (mid <= slot) {
3654 if (nritems == 1 ||
3655 leaf_space_used(l, mid, nritems - mid) + data_size >
3656 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3657 if (slot >= nritems) {
3658 split = 0;
3659 } else {
3660 mid = slot;
3661 if (mid != nritems &&
3662 leaf_space_used(l, mid, nritems - mid) +
3663 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3664 if (data_size && !tried_avoid_double)
3665 goto push_for_double;
3666 split = 2;
3667 }
3668 }
3669 }
3670 } else {
3671 if (leaf_space_used(l, 0, mid) + data_size >
3672 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3673 if (!extend && data_size && slot == 0) {
3674 split = 0;
3675 } else if ((extend || !data_size) && slot == 0) {
3676 mid = 1;
3677 } else {
3678 mid = slot;
3679 if (mid != nritems &&
3680 leaf_space_used(l, mid, nritems - mid) +
3681 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3682 if (data_size && !tried_avoid_double)
3683 goto push_for_double;
3684 split = 2;
3685 }
3686 }
3687 }
3688 }
3689
3690 if (split == 0)
3691 btrfs_cpu_key_to_disk(&disk_key, ins_key);
3692 else
3693 btrfs_item_key(l, &disk_key, mid);
3694
3695 /*
3696 * We have to about BTRFS_NESTING_NEW_ROOT here if we've done a double
3697 * split, because we're only allowed to have MAX_LOCKDEP_SUBCLASSES
3698 * subclasses, which is 8 at the time of this patch, and we've maxed it
3699 * out. In the future we could add a
3700 * BTRFS_NESTING_SPLIT_THE_SPLITTENING if we need to, but for now just
3701 * use BTRFS_NESTING_NEW_ROOT.
3702 */
3703 right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
3704 &disk_key, 0, l->start, 0,
3705 num_doubles ? BTRFS_NESTING_NEW_ROOT :
3706 BTRFS_NESTING_SPLIT);
3707 if (IS_ERR(right))
3708 return PTR_ERR(right);
3709
3710 root_add_used(root, fs_info->nodesize);
3711
3712 if (split == 0) {
3713 if (mid <= slot) {
3714 btrfs_set_header_nritems(right, 0);
3715 insert_ptr(trans, path, &disk_key,
3716 right->start, path->slots[1] + 1, 1);
3717 btrfs_tree_unlock(path->nodes[0]);
3718 free_extent_buffer(path->nodes[0]);
3719 path->nodes[0] = right;
3720 path->slots[0] = 0;
3721 path->slots[1] += 1;
3722 } else {
3723 btrfs_set_header_nritems(right, 0);
3724 insert_ptr(trans, path, &disk_key,
3725 right->start, path->slots[1], 1);
3726 btrfs_tree_unlock(path->nodes[0]);
3727 free_extent_buffer(path->nodes[0]);
3728 path->nodes[0] = right;
3729 path->slots[0] = 0;
3730 if (path->slots[1] == 0)
3731 fixup_low_keys(path, &disk_key, 1);
3732 }
3733 /*
3734 * We create a new leaf 'right' for the required ins_len and
3735 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
3736 * the content of ins_len to 'right'.
3737 */
3738 return ret;
3739 }
3740
3741 copy_for_split(trans, path, l, right, slot, mid, nritems);
3742
3743 if (split == 2) {
3744 BUG_ON(num_doubles != 0);
3745 num_doubles++;
3746 goto again;
3747 }
3748
3749 return 0;
3750
3751push_for_double:
3752 push_for_double_split(trans, root, path, data_size);
3753 tried_avoid_double = 1;
3754 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3755 return 0;
3756 goto again;
3757}
3758
3759static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3760 struct btrfs_root *root,
3761 struct btrfs_path *path, int ins_len)
3762{
3763 struct btrfs_key key;
3764 struct extent_buffer *leaf;
3765 struct btrfs_file_extent_item *fi;
3766 u64 extent_len = 0;
3767 u32 item_size;
3768 int ret;
3769
3770 leaf = path->nodes[0];
3771 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3772
3773 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3774 key.type != BTRFS_EXTENT_CSUM_KEY);
3775
3776 if (btrfs_leaf_free_space(leaf) >= ins_len)
3777 return 0;
3778
3779 item_size = btrfs_item_size(leaf, path->slots[0]);
3780 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3781 fi = btrfs_item_ptr(leaf, path->slots[0],
3782 struct btrfs_file_extent_item);
3783 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3784 }
3785 btrfs_release_path(path);
3786
3787 path->keep_locks = 1;
3788 path->search_for_split = 1;
3789 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3790 path->search_for_split = 0;
3791 if (ret > 0)
3792 ret = -EAGAIN;
3793 if (ret < 0)
3794 goto err;
3795
3796 ret = -EAGAIN;
3797 leaf = path->nodes[0];
3798 /* if our item isn't there, return now */
3799 if (item_size != btrfs_item_size(leaf, path->slots[0]))
3800 goto err;
3801
3802 /* the leaf has changed, it now has room. return now */
3803 if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
3804 goto err;
3805
3806 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3807 fi = btrfs_item_ptr(leaf, path->slots[0],
3808 struct btrfs_file_extent_item);
3809 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3810 goto err;
3811 }
3812
3813 ret = split_leaf(trans, root, &key, path, ins_len, 1);
3814 if (ret)
3815 goto err;
3816
3817 path->keep_locks = 0;
3818 btrfs_unlock_up_safe(path, 1);
3819 return 0;
3820err:
3821 path->keep_locks = 0;
3822 return ret;
3823}
3824
3825static noinline int split_item(struct btrfs_path *path,
3826 const struct btrfs_key *new_key,
3827 unsigned long split_offset)
3828{
3829 struct extent_buffer *leaf;
3830 int orig_slot, slot;
3831 char *buf;
3832 u32 nritems;
3833 u32 item_size;
3834 u32 orig_offset;
3835 struct btrfs_disk_key disk_key;
3836
3837 leaf = path->nodes[0];
3838 BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));
3839
3840 orig_slot = path->slots[0];
3841 orig_offset = btrfs_item_offset(leaf, path->slots[0]);
3842 item_size = btrfs_item_size(leaf, path->slots[0]);
3843
3844 buf = kmalloc(item_size, GFP_NOFS);
3845 if (!buf)
3846 return -ENOMEM;
3847
3848 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3849 path->slots[0]), item_size);
3850
3851 slot = path->slots[0] + 1;
3852 nritems = btrfs_header_nritems(leaf);
3853 if (slot != nritems) {
3854 /* shift the items */
3855 memmove_leaf_items(leaf, slot + 1, slot, nritems - slot);
3856 }
3857
3858 btrfs_cpu_key_to_disk(&disk_key, new_key);
3859 btrfs_set_item_key(leaf, &disk_key, slot);
3860
3861 btrfs_set_item_offset(leaf, slot, orig_offset);
3862 btrfs_set_item_size(leaf, slot, item_size - split_offset);
3863
3864 btrfs_set_item_offset(leaf, orig_slot,
3865 orig_offset + item_size - split_offset);
3866 btrfs_set_item_size(leaf, orig_slot, split_offset);
3867
3868 btrfs_set_header_nritems(leaf, nritems + 1);
3869
3870 /* write the data for the start of the original item */
3871 write_extent_buffer(leaf, buf,
3872 btrfs_item_ptr_offset(leaf, path->slots[0]),
3873 split_offset);
3874
3875 /* write the data for the new item */
3876 write_extent_buffer(leaf, buf + split_offset,
3877 btrfs_item_ptr_offset(leaf, slot),
3878 item_size - split_offset);
3879 btrfs_mark_buffer_dirty(leaf);
3880
3881 BUG_ON(btrfs_leaf_free_space(leaf) < 0);
3882 kfree(buf);
3883 return 0;
3884}
3885
3886/*
3887 * This function splits a single item into two items,
3888 * giving 'new_key' to the new item and splitting the
3889 * old one at split_offset (from the start of the item).
3890 *
3891 * The path may be released by this operation. After
3892 * the split, the path is pointing to the old item. The
3893 * new item is going to be in the same node as the old one.
3894 *
3895 * Note, the item being split must be smaller enough to live alone on
3896 * a tree block with room for one extra struct btrfs_item
3897 *
3898 * This allows us to split the item in place, keeping a lock on the
3899 * leaf the entire time.
3900 */
3901int btrfs_split_item(struct btrfs_trans_handle *trans,
3902 struct btrfs_root *root,
3903 struct btrfs_path *path,
3904 const struct btrfs_key *new_key,
3905 unsigned long split_offset)
3906{
3907 int ret;
3908 ret = setup_leaf_for_split(trans, root, path,
3909 sizeof(struct btrfs_item));
3910 if (ret)
3911 return ret;
3912
3913 ret = split_item(path, new_key, split_offset);
3914 return ret;
3915}
3916
3917/*
3918 * make the item pointed to by the path smaller. new_size indicates
3919 * how small to make it, and from_end tells us if we just chop bytes
3920 * off the end of the item or if we shift the item to chop bytes off
3921 * the front.
3922 */
3923void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end)
3924{
3925 int slot;
3926 struct extent_buffer *leaf;
3927 u32 nritems;
3928 unsigned int data_end;
3929 unsigned int old_data_start;
3930 unsigned int old_size;
3931 unsigned int size_diff;
3932 int i;
3933 struct btrfs_map_token token;
3934
3935 leaf = path->nodes[0];
3936 slot = path->slots[0];
3937
3938 old_size = btrfs_item_size(leaf, slot);
3939 if (old_size == new_size)
3940 return;
3941
3942 nritems = btrfs_header_nritems(leaf);
3943 data_end = leaf_data_end(leaf);
3944
3945 old_data_start = btrfs_item_offset(leaf, slot);
3946
3947 size_diff = old_size - new_size;
3948
3949 BUG_ON(slot < 0);
3950 BUG_ON(slot >= nritems);
3951
3952 /*
3953 * item0..itemN ... dataN.offset..dataN.size .. data0.size
3954 */
3955 /* first correct the data pointers */
3956 btrfs_init_map_token(&token, leaf);
3957 for (i = slot; i < nritems; i++) {
3958 u32 ioff;
3959
3960 ioff = btrfs_token_item_offset(&token, i);
3961 btrfs_set_token_item_offset(&token, i, ioff + size_diff);
3962 }
3963
3964 /* shift the data */
3965 if (from_end) {
3966 memmove_leaf_data(leaf, data_end + size_diff, data_end,
3967 old_data_start + new_size - data_end);
3968 } else {
3969 struct btrfs_disk_key disk_key;
3970 u64 offset;
3971
3972 btrfs_item_key(leaf, &disk_key, slot);
3973
3974 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
3975 unsigned long ptr;
3976 struct btrfs_file_extent_item *fi;
3977
3978 fi = btrfs_item_ptr(leaf, slot,
3979 struct btrfs_file_extent_item);
3980 fi = (struct btrfs_file_extent_item *)(
3981 (unsigned long)fi - size_diff);
3982
3983 if (btrfs_file_extent_type(leaf, fi) ==
3984 BTRFS_FILE_EXTENT_INLINE) {
3985 ptr = btrfs_item_ptr_offset(leaf, slot);
3986 memmove_extent_buffer(leaf, ptr,
3987 (unsigned long)fi,
3988 BTRFS_FILE_EXTENT_INLINE_DATA_START);
3989 }
3990 }
3991
3992 memmove_leaf_data(leaf, data_end + size_diff, data_end,
3993 old_data_start - data_end);
3994
3995 offset = btrfs_disk_key_offset(&disk_key);
3996 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
3997 btrfs_set_item_key(leaf, &disk_key, slot);
3998 if (slot == 0)
3999 fixup_low_keys(path, &disk_key, 1);
4000 }
4001
4002 btrfs_set_item_size(leaf, slot, new_size);
4003 btrfs_mark_buffer_dirty(leaf);
4004
4005 if (btrfs_leaf_free_space(leaf) < 0) {
4006 btrfs_print_leaf(leaf);
4007 BUG();
4008 }
4009}
4010
4011/*
4012 * make the item pointed to by the path bigger, data_size is the added size.
4013 */
4014void btrfs_extend_item(struct btrfs_path *path, u32 data_size)
4015{
4016 int slot;
4017 struct extent_buffer *leaf;
4018 u32 nritems;
4019 unsigned int data_end;
4020 unsigned int old_data;
4021 unsigned int old_size;
4022 int i;
4023 struct btrfs_map_token token;
4024
4025 leaf = path->nodes[0];
4026
4027 nritems = btrfs_header_nritems(leaf);
4028 data_end = leaf_data_end(leaf);
4029
4030 if (btrfs_leaf_free_space(leaf) < data_size) {
4031 btrfs_print_leaf(leaf);
4032 BUG();
4033 }
4034 slot = path->slots[0];
4035 old_data = btrfs_item_data_end(leaf, slot);
4036
4037 BUG_ON(slot < 0);
4038 if (slot >= nritems) {
4039 btrfs_print_leaf(leaf);
4040 btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
4041 slot, nritems);
4042 BUG();
4043 }
4044
4045 /*
4046 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4047 */
4048 /* first correct the data pointers */
4049 btrfs_init_map_token(&token, leaf);
4050 for (i = slot; i < nritems; i++) {
4051 u32 ioff;
4052
4053 ioff = btrfs_token_item_offset(&token, i);
4054 btrfs_set_token_item_offset(&token, i, ioff - data_size);
4055 }
4056
4057 /* shift the data */
4058 memmove_leaf_data(leaf, data_end - data_size, data_end,
4059 old_data - data_end);
4060
4061 data_end = old_data;
4062 old_size = btrfs_item_size(leaf, slot);
4063 btrfs_set_item_size(leaf, slot, old_size + data_size);
4064 btrfs_mark_buffer_dirty(leaf);
4065
4066 if (btrfs_leaf_free_space(leaf) < 0) {
4067 btrfs_print_leaf(leaf);
4068 BUG();
4069 }
4070}
4071
4072/*
4073 * Make space in the node before inserting one or more items.
4074 *
4075 * @root: root we are inserting items to
4076 * @path: points to the leaf/slot where we are going to insert new items
4077 * @batch: information about the batch of items to insert
4078 *
4079 * Main purpose is to save stack depth by doing the bulk of the work in a
4080 * function that doesn't call btrfs_search_slot
4081 */
4082static void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
4083 const struct btrfs_item_batch *batch)
4084{
4085 struct btrfs_fs_info *fs_info = root->fs_info;
4086 int i;
4087 u32 nritems;
4088 unsigned int data_end;
4089 struct btrfs_disk_key disk_key;
4090 struct extent_buffer *leaf;
4091 int slot;
4092 struct btrfs_map_token token;
4093 u32 total_size;
4094
4095 /*
4096 * Before anything else, update keys in the parent and other ancestors
4097 * if needed, then release the write locks on them, so that other tasks
4098 * can use them while we modify the leaf.
4099 */
4100 if (path->slots[0] == 0) {
4101 btrfs_cpu_key_to_disk(&disk_key, &batch->keys[0]);
4102 fixup_low_keys(path, &disk_key, 1);
4103 }
4104 btrfs_unlock_up_safe(path, 1);
4105
4106 leaf = path->nodes[0];
4107 slot = path->slots[0];
4108
4109 nritems = btrfs_header_nritems(leaf);
4110 data_end = leaf_data_end(leaf);
4111 total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
4112
4113 if (btrfs_leaf_free_space(leaf) < total_size) {
4114 btrfs_print_leaf(leaf);
4115 btrfs_crit(fs_info, "not enough freespace need %u have %d",
4116 total_size, btrfs_leaf_free_space(leaf));
4117 BUG();
4118 }
4119
4120 btrfs_init_map_token(&token, leaf);
4121 if (slot != nritems) {
4122 unsigned int old_data = btrfs_item_data_end(leaf, slot);
4123
4124 if (old_data < data_end) {
4125 btrfs_print_leaf(leaf);
4126 btrfs_crit(fs_info,
4127 "item at slot %d with data offset %u beyond data end of leaf %u",
4128 slot, old_data, data_end);
4129 BUG();
4130 }
4131 /*
4132 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4133 */
4134 /* first correct the data pointers */
4135 for (i = slot; i < nritems; i++) {
4136 u32 ioff;
4137
4138 ioff = btrfs_token_item_offset(&token, i);
4139 btrfs_set_token_item_offset(&token, i,
4140 ioff - batch->total_data_size);
4141 }
4142 /* shift the items */
4143 memmove_leaf_items(leaf, slot + batch->nr, slot, nritems - slot);
4144
4145 /* shift the data */
4146 memmove_leaf_data(leaf, data_end - batch->total_data_size,
4147 data_end, old_data - data_end);
4148 data_end = old_data;
4149 }
4150
4151 /* setup the item for the new data */
4152 for (i = 0; i < batch->nr; i++) {
4153 btrfs_cpu_key_to_disk(&disk_key, &batch->keys[i]);
4154 btrfs_set_item_key(leaf, &disk_key, slot + i);
4155 data_end -= batch->data_sizes[i];
4156 btrfs_set_token_item_offset(&token, slot + i, data_end);
4157 btrfs_set_token_item_size(&token, slot + i, batch->data_sizes[i]);
4158 }
4159
4160 btrfs_set_header_nritems(leaf, nritems + batch->nr);
4161 btrfs_mark_buffer_dirty(leaf);
4162
4163 if (btrfs_leaf_free_space(leaf) < 0) {
4164 btrfs_print_leaf(leaf);
4165 BUG();
4166 }
4167}
4168
4169/*
4170 * Insert a new item into a leaf.
4171 *
4172 * @root: The root of the btree.
4173 * @path: A path pointing to the target leaf and slot.
4174 * @key: The key of the new item.
4175 * @data_size: The size of the data associated with the new key.
4176 */
4177void btrfs_setup_item_for_insert(struct btrfs_root *root,
4178 struct btrfs_path *path,
4179 const struct btrfs_key *key,
4180 u32 data_size)
4181{
4182 struct btrfs_item_batch batch;
4183
4184 batch.keys = key;
4185 batch.data_sizes = &data_size;
4186 batch.total_data_size = data_size;
4187 batch.nr = 1;
4188
4189 setup_items_for_insert(root, path, &batch);
4190}
4191
4192/*
4193 * Given a key and some data, insert items into the tree.
4194 * This does all the path init required, making room in the tree if needed.
4195 */
4196int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4197 struct btrfs_root *root,
4198 struct btrfs_path *path,
4199 const struct btrfs_item_batch *batch)
4200{
4201 int ret = 0;
4202 int slot;
4203 u32 total_size;
4204
4205 total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
4206 ret = btrfs_search_slot(trans, root, &batch->keys[0], path, total_size, 1);
4207 if (ret == 0)
4208 return -EEXIST;
4209 if (ret < 0)
4210 return ret;
4211
4212 slot = path->slots[0];
4213 BUG_ON(slot < 0);
4214
4215 setup_items_for_insert(root, path, batch);
4216 return 0;
4217}
4218
4219/*
4220 * Given a key and some data, insert an item into the tree.
4221 * This does all the path init required, making room in the tree if needed.
4222 */
4223int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4224 const struct btrfs_key *cpu_key, void *data,
4225 u32 data_size)
4226{
4227 int ret = 0;
4228 struct btrfs_path *path;
4229 struct extent_buffer *leaf;
4230 unsigned long ptr;
4231
4232 path = btrfs_alloc_path();
4233 if (!path)
4234 return -ENOMEM;
4235 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4236 if (!ret) {
4237 leaf = path->nodes[0];
4238 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4239 write_extent_buffer(leaf, data, ptr, data_size);
4240 btrfs_mark_buffer_dirty(leaf);
4241 }
4242 btrfs_free_path(path);
4243 return ret;
4244}
4245
4246/*
4247 * This function duplicates an item, giving 'new_key' to the new item.
4248 * It guarantees both items live in the same tree leaf and the new item is
4249 * contiguous with the original item.
4250 *
4251 * This allows us to split a file extent in place, keeping a lock on the leaf
4252 * the entire time.
4253 */
4254int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4255 struct btrfs_root *root,
4256 struct btrfs_path *path,
4257 const struct btrfs_key *new_key)
4258{
4259 struct extent_buffer *leaf;
4260 int ret;
4261 u32 item_size;
4262
4263 leaf = path->nodes[0];
4264 item_size = btrfs_item_size(leaf, path->slots[0]);
4265 ret = setup_leaf_for_split(trans, root, path,
4266 item_size + sizeof(struct btrfs_item));
4267 if (ret)
4268 return ret;
4269
4270 path->slots[0]++;
4271 btrfs_setup_item_for_insert(root, path, new_key, item_size);
4272 leaf = path->nodes[0];
4273 memcpy_extent_buffer(leaf,
4274 btrfs_item_ptr_offset(leaf, path->slots[0]),
4275 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4276 item_size);
4277 return 0;
4278}
4279
4280/*
4281 * delete the pointer from a given node.
4282 *
4283 * the tree should have been previously balanced so the deletion does not
4284 * empty a node.
4285 */
4286static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
4287 int level, int slot)
4288{
4289 struct extent_buffer *parent = path->nodes[level];
4290 u32 nritems;
4291 int ret;
4292
4293 nritems = btrfs_header_nritems(parent);
4294 if (slot != nritems - 1) {
4295 if (level) {
4296 ret = btrfs_tree_mod_log_insert_move(parent, slot,
4297 slot + 1, nritems - slot - 1);
4298 BUG_ON(ret < 0);
4299 }
4300 memmove_extent_buffer(parent,
4301 btrfs_node_key_ptr_offset(parent, slot),
4302 btrfs_node_key_ptr_offset(parent, slot + 1),
4303 sizeof(struct btrfs_key_ptr) *
4304 (nritems - slot - 1));
4305 } else if (level) {
4306 ret = btrfs_tree_mod_log_insert_key(parent, slot,
4307 BTRFS_MOD_LOG_KEY_REMOVE);
4308 BUG_ON(ret < 0);
4309 }
4310
4311 nritems--;
4312 btrfs_set_header_nritems(parent, nritems);
4313 if (nritems == 0 && parent == root->node) {
4314 BUG_ON(btrfs_header_level(root->node) != 1);
4315 /* just turn the root into a leaf and break */
4316 btrfs_set_header_level(root->node, 0);
4317 } else if (slot == 0) {
4318 struct btrfs_disk_key disk_key;
4319
4320 btrfs_node_key(parent, &disk_key, 0);
4321 fixup_low_keys(path, &disk_key, level + 1);
4322 }
4323 btrfs_mark_buffer_dirty(parent);
4324}
4325
4326/*
4327 * a helper function to delete the leaf pointed to by path->slots[1] and
4328 * path->nodes[1].
4329 *
4330 * This deletes the pointer in path->nodes[1] and frees the leaf
4331 * block extent. zero is returned if it all worked out, < 0 otherwise.
4332 *
4333 * The path must have already been setup for deleting the leaf, including
4334 * all the proper balancing. path->nodes[1] must be locked.
4335 */
4336static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4337 struct btrfs_root *root,
4338 struct btrfs_path *path,
4339 struct extent_buffer *leaf)
4340{
4341 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4342 del_ptr(root, path, 1, path->slots[1]);
4343
4344 /*
4345 * btrfs_free_extent is expensive, we want to make sure we
4346 * aren't holding any locks when we call it
4347 */
4348 btrfs_unlock_up_safe(path, 0);
4349
4350 root_sub_used(root, leaf->len);
4351
4352 atomic_inc(&leaf->refs);
4353 btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
4354 free_extent_buffer_stale(leaf);
4355}
4356/*
4357 * delete the item at the leaf level in path. If that empties
4358 * the leaf, remove it from the tree
4359 */
4360int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4361 struct btrfs_path *path, int slot, int nr)
4362{
4363 struct btrfs_fs_info *fs_info = root->fs_info;
4364 struct extent_buffer *leaf;
4365 int ret = 0;
4366 int wret;
4367 u32 nritems;
4368
4369 leaf = path->nodes[0];
4370 nritems = btrfs_header_nritems(leaf);
4371
4372 if (slot + nr != nritems) {
4373 const u32 last_off = btrfs_item_offset(leaf, slot + nr - 1);
4374 const int data_end = leaf_data_end(leaf);
4375 struct btrfs_map_token token;
4376 u32 dsize = 0;
4377 int i;
4378
4379 for (i = 0; i < nr; i++)
4380 dsize += btrfs_item_size(leaf, slot + i);
4381
4382 memmove_leaf_data(leaf, data_end + dsize, data_end,
4383 last_off - data_end);
4384
4385 btrfs_init_map_token(&token, leaf);
4386 for (i = slot + nr; i < nritems; i++) {
4387 u32 ioff;
4388
4389 ioff = btrfs_token_item_offset(&token, i);
4390 btrfs_set_token_item_offset(&token, i, ioff + dsize);
4391 }
4392
4393 memmove_leaf_items(leaf, slot, slot + nr, nritems - slot - nr);
4394 }
4395 btrfs_set_header_nritems(leaf, nritems - nr);
4396 nritems -= nr;
4397
4398 /* delete the leaf if we've emptied it */
4399 if (nritems == 0) {
4400 if (leaf == root->node) {
4401 btrfs_set_header_level(leaf, 0);
4402 } else {
4403 btrfs_clean_tree_block(leaf);
4404 btrfs_del_leaf(trans, root, path, leaf);
4405 }
4406 } else {
4407 int used = leaf_space_used(leaf, 0, nritems);
4408 if (slot == 0) {
4409 struct btrfs_disk_key disk_key;
4410
4411 btrfs_item_key(leaf, &disk_key, 0);
4412 fixup_low_keys(path, &disk_key, 1);
4413 }
4414
4415 /*
4416 * Try to delete the leaf if it is mostly empty. We do this by
4417 * trying to move all its items into its left and right neighbours.
4418 * If we can't move all the items, then we don't delete it - it's
4419 * not ideal, but future insertions might fill the leaf with more
4420 * items, or items from other leaves might be moved later into our
4421 * leaf due to deletions on those leaves.
4422 */
4423 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
4424 u32 min_push_space;
4425
4426 /* push_leaf_left fixes the path.
4427 * make sure the path still points to our leaf
4428 * for possible call to del_ptr below
4429 */
4430 slot = path->slots[1];
4431 atomic_inc(&leaf->refs);
4432 /*
4433 * We want to be able to at least push one item to the
4434 * left neighbour leaf, and that's the first item.
4435 */
4436 min_push_space = sizeof(struct btrfs_item) +
4437 btrfs_item_size(leaf, 0);
4438 wret = push_leaf_left(trans, root, path, 0,
4439 min_push_space, 1, (u32)-1);
4440 if (wret < 0 && wret != -ENOSPC)
4441 ret = wret;
4442
4443 if (path->nodes[0] == leaf &&
4444 btrfs_header_nritems(leaf)) {
4445 /*
4446 * If we were not able to push all items from our
4447 * leaf to its left neighbour, then attempt to
4448 * either push all the remaining items to the
4449 * right neighbour or none. There's no advantage
4450 * in pushing only some items, instead of all, as
4451 * it's pointless to end up with a leaf having
4452 * too few items while the neighbours can be full
4453 * or nearly full.
4454 */
4455 nritems = btrfs_header_nritems(leaf);
4456 min_push_space = leaf_space_used(leaf, 0, nritems);
4457 wret = push_leaf_right(trans, root, path, 0,
4458 min_push_space, 1, 0);
4459 if (wret < 0 && wret != -ENOSPC)
4460 ret = wret;
4461 }
4462
4463 if (btrfs_header_nritems(leaf) == 0) {
4464 path->slots[1] = slot;
4465 btrfs_del_leaf(trans, root, path, leaf);
4466 free_extent_buffer(leaf);
4467 ret = 0;
4468 } else {
4469 /* if we're still in the path, make sure
4470 * we're dirty. Otherwise, one of the
4471 * push_leaf functions must have already
4472 * dirtied this buffer
4473 */
4474 if (path->nodes[0] == leaf)
4475 btrfs_mark_buffer_dirty(leaf);
4476 free_extent_buffer(leaf);
4477 }
4478 } else {
4479 btrfs_mark_buffer_dirty(leaf);
4480 }
4481 }
4482 return ret;
4483}
4484
4485/*
4486 * search the tree again to find a leaf with lesser keys
4487 * returns 0 if it found something or 1 if there are no lesser leaves.
4488 * returns < 0 on io errors.
4489 *
4490 * This may release the path, and so you may lose any locks held at the
4491 * time you call it.
4492 */
4493int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
4494{
4495 struct btrfs_key key;
4496 struct btrfs_disk_key found_key;
4497 int ret;
4498
4499 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
4500
4501 if (key.offset > 0) {
4502 key.offset--;
4503 } else if (key.type > 0) {
4504 key.type--;
4505 key.offset = (u64)-1;
4506 } else if (key.objectid > 0) {
4507 key.objectid--;
4508 key.type = (u8)-1;
4509 key.offset = (u64)-1;
4510 } else {
4511 return 1;
4512 }
4513
4514 btrfs_release_path(path);
4515 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4516 if (ret < 0)
4517 return ret;
4518 btrfs_item_key(path->nodes[0], &found_key, 0);
4519 ret = comp_keys(&found_key, &key);
4520 /*
4521 * We might have had an item with the previous key in the tree right
4522 * before we released our path. And after we released our path, that
4523 * item might have been pushed to the first slot (0) of the leaf we
4524 * were holding due to a tree balance. Alternatively, an item with the
4525 * previous key can exist as the only element of a leaf (big fat item).
4526 * Therefore account for these 2 cases, so that our callers (like
4527 * btrfs_previous_item) don't miss an existing item with a key matching
4528 * the previous key we computed above.
4529 */
4530 if (ret <= 0)
4531 return 0;
4532 return 1;
4533}
4534
4535/*
4536 * A helper function to walk down the tree starting at min_key, and looking
4537 * for nodes or leaves that are have a minimum transaction id.
4538 * This is used by the btree defrag code, and tree logging
4539 *
4540 * This does not cow, but it does stuff the starting key it finds back
4541 * into min_key, so you can call btrfs_search_slot with cow=1 on the
4542 * key and get a writable path.
4543 *
4544 * This honors path->lowest_level to prevent descent past a given level
4545 * of the tree.
4546 *
4547 * min_trans indicates the oldest transaction that you are interested
4548 * in walking through. Any nodes or leaves older than min_trans are
4549 * skipped over (without reading them).
4550 *
4551 * returns zero if something useful was found, < 0 on error and 1 if there
4552 * was nothing in the tree that matched the search criteria.
4553 */
4554int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4555 struct btrfs_path *path,
4556 u64 min_trans)
4557{
4558 struct extent_buffer *cur;
4559 struct btrfs_key found_key;
4560 int slot;
4561 int sret;
4562 u32 nritems;
4563 int level;
4564 int ret = 1;
4565 int keep_locks = path->keep_locks;
4566
4567 ASSERT(!path->nowait);
4568 path->keep_locks = 1;
4569again:
4570 cur = btrfs_read_lock_root_node(root);
4571 level = btrfs_header_level(cur);
4572 WARN_ON(path->nodes[level]);
4573 path->nodes[level] = cur;
4574 path->locks[level] = BTRFS_READ_LOCK;
4575
4576 if (btrfs_header_generation(cur) < min_trans) {
4577 ret = 1;
4578 goto out;
4579 }
4580 while (1) {
4581 nritems = btrfs_header_nritems(cur);
4582 level = btrfs_header_level(cur);
4583 sret = btrfs_bin_search(cur, min_key, &slot);
4584 if (sret < 0) {
4585 ret = sret;
4586 goto out;
4587 }
4588
4589 /* at the lowest level, we're done, setup the path and exit */
4590 if (level == path->lowest_level) {
4591 if (slot >= nritems)
4592 goto find_next_key;
4593 ret = 0;
4594 path->slots[level] = slot;
4595 btrfs_item_key_to_cpu(cur, &found_key, slot);
4596 goto out;
4597 }
4598 if (sret && slot > 0)
4599 slot--;
4600 /*
4601 * check this node pointer against the min_trans parameters.
4602 * If it is too old, skip to the next one.
4603 */
4604 while (slot < nritems) {
4605 u64 gen;
4606
4607 gen = btrfs_node_ptr_generation(cur, slot);
4608 if (gen < min_trans) {
4609 slot++;
4610 continue;
4611 }
4612 break;
4613 }
4614find_next_key:
4615 /*
4616 * we didn't find a candidate key in this node, walk forward
4617 * and find another one
4618 */
4619 if (slot >= nritems) {
4620 path->slots[level] = slot;
4621 sret = btrfs_find_next_key(root, path, min_key, level,
4622 min_trans);
4623 if (sret == 0) {
4624 btrfs_release_path(path);
4625 goto again;
4626 } else {
4627 goto out;
4628 }
4629 }
4630 /* save our key for returning back */
4631 btrfs_node_key_to_cpu(cur, &found_key, slot);
4632 path->slots[level] = slot;
4633 if (level == path->lowest_level) {
4634 ret = 0;
4635 goto out;
4636 }
4637 cur = btrfs_read_node_slot(cur, slot);
4638 if (IS_ERR(cur)) {
4639 ret = PTR_ERR(cur);
4640 goto out;
4641 }
4642
4643 btrfs_tree_read_lock(cur);
4644
4645 path->locks[level - 1] = BTRFS_READ_LOCK;
4646 path->nodes[level - 1] = cur;
4647 unlock_up(path, level, 1, 0, NULL);
4648 }
4649out:
4650 path->keep_locks = keep_locks;
4651 if (ret == 0) {
4652 btrfs_unlock_up_safe(path, path->lowest_level + 1);
4653 memcpy(min_key, &found_key, sizeof(found_key));
4654 }
4655 return ret;
4656}
4657
4658/*
4659 * this is similar to btrfs_next_leaf, but does not try to preserve
4660 * and fixup the path. It looks for and returns the next key in the
4661 * tree based on the current path and the min_trans parameters.
4662 *
4663 * 0 is returned if another key is found, < 0 if there are any errors
4664 * and 1 is returned if there are no higher keys in the tree
4665 *
4666 * path->keep_locks should be set to 1 on the search made before
4667 * calling this function.
4668 */
4669int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4670 struct btrfs_key *key, int level, u64 min_trans)
4671{
4672 int slot;
4673 struct extent_buffer *c;
4674
4675 WARN_ON(!path->keep_locks && !path->skip_locking);
4676 while (level < BTRFS_MAX_LEVEL) {
4677 if (!path->nodes[level])
4678 return 1;
4679
4680 slot = path->slots[level] + 1;
4681 c = path->nodes[level];
4682next:
4683 if (slot >= btrfs_header_nritems(c)) {
4684 int ret;
4685 int orig_lowest;
4686 struct btrfs_key cur_key;
4687 if (level + 1 >= BTRFS_MAX_LEVEL ||
4688 !path->nodes[level + 1])
4689 return 1;
4690
4691 if (path->locks[level + 1] || path->skip_locking) {
4692 level++;
4693 continue;
4694 }
4695
4696 slot = btrfs_header_nritems(c) - 1;
4697 if (level == 0)
4698 btrfs_item_key_to_cpu(c, &cur_key, slot);
4699 else
4700 btrfs_node_key_to_cpu(c, &cur_key, slot);
4701
4702 orig_lowest = path->lowest_level;
4703 btrfs_release_path(path);
4704 path->lowest_level = level;
4705 ret = btrfs_search_slot(NULL, root, &cur_key, path,
4706 0, 0);
4707 path->lowest_level = orig_lowest;
4708 if (ret < 0)
4709 return ret;
4710
4711 c = path->nodes[level];
4712 slot = path->slots[level];
4713 if (ret == 0)
4714 slot++;
4715 goto next;
4716 }
4717
4718 if (level == 0)
4719 btrfs_item_key_to_cpu(c, key, slot);
4720 else {
4721 u64 gen = btrfs_node_ptr_generation(c, slot);
4722
4723 if (gen < min_trans) {
4724 slot++;
4725 goto next;
4726 }
4727 btrfs_node_key_to_cpu(c, key, slot);
4728 }
4729 return 0;
4730 }
4731 return 1;
4732}
4733
4734int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
4735 u64 time_seq)
4736{
4737 int slot;
4738 int level;
4739 struct extent_buffer *c;
4740 struct extent_buffer *next;
4741 struct btrfs_fs_info *fs_info = root->fs_info;
4742 struct btrfs_key key;
4743 bool need_commit_sem = false;
4744 u32 nritems;
4745 int ret;
4746 int i;
4747
4748 /*
4749 * The nowait semantics are used only for write paths, where we don't
4750 * use the tree mod log and sequence numbers.
4751 */
4752 if (time_seq)
4753 ASSERT(!path->nowait);
4754
4755 nritems = btrfs_header_nritems(path->nodes[0]);
4756 if (nritems == 0)
4757 return 1;
4758
4759 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
4760again:
4761 level = 1;
4762 next = NULL;
4763 btrfs_release_path(path);
4764
4765 path->keep_locks = 1;
4766
4767 if (time_seq) {
4768 ret = btrfs_search_old_slot(root, &key, path, time_seq);
4769 } else {
4770 if (path->need_commit_sem) {
4771 path->need_commit_sem = 0;
4772 need_commit_sem = true;
4773 if (path->nowait) {
4774 if (!down_read_trylock(&fs_info->commit_root_sem)) {
4775 ret = -EAGAIN;
4776 goto done;
4777 }
4778 } else {
4779 down_read(&fs_info->commit_root_sem);
4780 }
4781 }
4782 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4783 }
4784 path->keep_locks = 0;
4785
4786 if (ret < 0)
4787 goto done;
4788
4789 nritems = btrfs_header_nritems(path->nodes[0]);
4790 /*
4791 * by releasing the path above we dropped all our locks. A balance
4792 * could have added more items next to the key that used to be
4793 * at the very end of the block. So, check again here and
4794 * advance the path if there are now more items available.
4795 */
4796 if (nritems > 0 && path->slots[0] < nritems - 1) {
4797 if (ret == 0)
4798 path->slots[0]++;
4799 ret = 0;
4800 goto done;
4801 }
4802 /*
4803 * So the above check misses one case:
4804 * - after releasing the path above, someone has removed the item that
4805 * used to be at the very end of the block, and balance between leafs
4806 * gets another one with bigger key.offset to replace it.
4807 *
4808 * This one should be returned as well, or we can get leaf corruption
4809 * later(esp. in __btrfs_drop_extents()).
4810 *
4811 * And a bit more explanation about this check,
4812 * with ret > 0, the key isn't found, the path points to the slot
4813 * where it should be inserted, so the path->slots[0] item must be the
4814 * bigger one.
4815 */
4816 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
4817 ret = 0;
4818 goto done;
4819 }
4820
4821 while (level < BTRFS_MAX_LEVEL) {
4822 if (!path->nodes[level]) {
4823 ret = 1;
4824 goto done;
4825 }
4826
4827 slot = path->slots[level] + 1;
4828 c = path->nodes[level];
4829 if (slot >= btrfs_header_nritems(c)) {
4830 level++;
4831 if (level == BTRFS_MAX_LEVEL) {
4832 ret = 1;
4833 goto done;
4834 }
4835 continue;
4836 }
4837
4838
4839 /*
4840 * Our current level is where we're going to start from, and to
4841 * make sure lockdep doesn't complain we need to drop our locks
4842 * and nodes from 0 to our current level.
4843 */
4844 for (i = 0; i < level; i++) {
4845 if (path->locks[level]) {
4846 btrfs_tree_read_unlock(path->nodes[i]);
4847 path->locks[i] = 0;
4848 }
4849 free_extent_buffer(path->nodes[i]);
4850 path->nodes[i] = NULL;
4851 }
4852
4853 next = c;
4854 ret = read_block_for_search(root, path, &next, level,
4855 slot, &key);
4856 if (ret == -EAGAIN && !path->nowait)
4857 goto again;
4858
4859 if (ret < 0) {
4860 btrfs_release_path(path);
4861 goto done;
4862 }
4863
4864 if (!path->skip_locking) {
4865 ret = btrfs_try_tree_read_lock(next);
4866 if (!ret && path->nowait) {
4867 ret = -EAGAIN;
4868 goto done;
4869 }
4870 if (!ret && time_seq) {
4871 /*
4872 * If we don't get the lock, we may be racing
4873 * with push_leaf_left, holding that lock while
4874 * itself waiting for the leaf we've currently
4875 * locked. To solve this situation, we give up
4876 * on our lock and cycle.
4877 */
4878 free_extent_buffer(next);
4879 btrfs_release_path(path);
4880 cond_resched();
4881 goto again;
4882 }
4883 if (!ret)
4884 btrfs_tree_read_lock(next);
4885 }
4886 break;
4887 }
4888 path->slots[level] = slot;
4889 while (1) {
4890 level--;
4891 path->nodes[level] = next;
4892 path->slots[level] = 0;
4893 if (!path->skip_locking)
4894 path->locks[level] = BTRFS_READ_LOCK;
4895 if (!level)
4896 break;
4897
4898 ret = read_block_for_search(root, path, &next, level,
4899 0, &key);
4900 if (ret == -EAGAIN && !path->nowait)
4901 goto again;
4902
4903 if (ret < 0) {
4904 btrfs_release_path(path);
4905 goto done;
4906 }
4907
4908 if (!path->skip_locking) {
4909 if (path->nowait) {
4910 if (!btrfs_try_tree_read_lock(next)) {
4911 ret = -EAGAIN;
4912 goto done;
4913 }
4914 } else {
4915 btrfs_tree_read_lock(next);
4916 }
4917 }
4918 }
4919 ret = 0;
4920done:
4921 unlock_up(path, 0, 1, 0, NULL);
4922 if (need_commit_sem) {
4923 int ret2;
4924
4925 path->need_commit_sem = 1;
4926 ret2 = finish_need_commit_sem_search(path);
4927 up_read(&fs_info->commit_root_sem);
4928 if (ret2)
4929 ret = ret2;
4930 }
4931
4932 return ret;
4933}
4934
4935int btrfs_next_old_item(struct btrfs_root *root, struct btrfs_path *path, u64 time_seq)
4936{
4937 path->slots[0]++;
4938 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
4939 return btrfs_next_old_leaf(root, path, time_seq);
4940 return 0;
4941}
4942
4943/*
4944 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
4945 * searching until it gets past min_objectid or finds an item of 'type'
4946 *
4947 * returns 0 if something is found, 1 if nothing was found and < 0 on error
4948 */
4949int btrfs_previous_item(struct btrfs_root *root,
4950 struct btrfs_path *path, u64 min_objectid,
4951 int type)
4952{
4953 struct btrfs_key found_key;
4954 struct extent_buffer *leaf;
4955 u32 nritems;
4956 int ret;
4957
4958 while (1) {
4959 if (path->slots[0] == 0) {
4960 ret = btrfs_prev_leaf(root, path);
4961 if (ret != 0)
4962 return ret;
4963 } else {
4964 path->slots[0]--;
4965 }
4966 leaf = path->nodes[0];
4967 nritems = btrfs_header_nritems(leaf);
4968 if (nritems == 0)
4969 return 1;
4970 if (path->slots[0] == nritems)
4971 path->slots[0]--;
4972
4973 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
4974 if (found_key.objectid < min_objectid)
4975 break;
4976 if (found_key.type == type)
4977 return 0;
4978 if (found_key.objectid == min_objectid &&
4979 found_key.type < type)
4980 break;
4981 }
4982 return 1;
4983}
4984
4985/*
4986 * search in extent tree to find a previous Metadata/Data extent item with
4987 * min objecitd.
4988 *
4989 * returns 0 if something is found, 1 if nothing was found and < 0 on error
4990 */
4991int btrfs_previous_extent_item(struct btrfs_root *root,
4992 struct btrfs_path *path, u64 min_objectid)
4993{
4994 struct btrfs_key found_key;
4995 struct extent_buffer *leaf;
4996 u32 nritems;
4997 int ret;
4998
4999 while (1) {
5000 if (path->slots[0] == 0) {
5001 ret = btrfs_prev_leaf(root, path);
5002 if (ret != 0)
5003 return ret;
5004 } else {
5005 path->slots[0]--;
5006 }
5007 leaf = path->nodes[0];
5008 nritems = btrfs_header_nritems(leaf);
5009 if (nritems == 0)
5010 return 1;
5011 if (path->slots[0] == nritems)
5012 path->slots[0]--;
5013
5014 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5015 if (found_key.objectid < min_objectid)
5016 break;
5017 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5018 found_key.type == BTRFS_METADATA_ITEM_KEY)
5019 return 0;
5020 if (found_key.objectid == min_objectid &&
5021 found_key.type < BTRFS_EXTENT_ITEM_KEY)
5022 break;
5023 }
5024 return 1;
5025}
5026
5027int __init btrfs_ctree_init(void)
5028{
5029 btrfs_path_cachep = kmem_cache_create("btrfs_path",
5030 sizeof(struct btrfs_path), 0,
5031 SLAB_MEM_SPREAD, NULL);
5032 if (!btrfs_path_cachep)
5033 return -ENOMEM;
5034 return 0;
5035}
5036
5037void __cold btrfs_ctree_exit(void)
5038{
5039 kmem_cache_destroy(btrfs_path_cachep);
5040}
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}