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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007,2008 Oracle. All rights reserved.
4 */
5
6#include <linux/sched.h>
7#include <linux/slab.h>
8#include <linux/rbtree.h>
9#include <linux/mm.h>
10#include <linux/error-injection.h>
11#include "messages.h"
12#include "ctree.h"
13#include "disk-io.h"
14#include "transaction.h"
15#include "print-tree.h"
16#include "locking.h"
17#include "volumes.h"
18#include "qgroup.h"
19#include "tree-mod-log.h"
20#include "tree-checker.h"
21#include "fs.h"
22#include "accessors.h"
23#include "extent-tree.h"
24#include "relocation.h"
25#include "file-item.h"
26
27static struct kmem_cache *btrfs_path_cachep;
28
29static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
30 *root, struct btrfs_path *path, int level);
31static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
32 const struct btrfs_key *ins_key, struct btrfs_path *path,
33 int data_size, int extend);
34static int push_node_left(struct btrfs_trans_handle *trans,
35 struct extent_buffer *dst,
36 struct extent_buffer *src, int empty);
37static int balance_node_right(struct btrfs_trans_handle *trans,
38 struct extent_buffer *dst_buf,
39 struct extent_buffer *src_buf);
40
41static const struct btrfs_csums {
42 u16 size;
43 const char name[10];
44 const char driver[12];
45} btrfs_csums[] = {
46 [BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
47 [BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
48 [BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
49 [BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
50 .driver = "blake2b-256" },
51};
52
53/*
54 * The leaf data grows from end-to-front in the node. this returns the address
55 * of the start of the last item, which is the stop of the leaf data stack.
56 */
57static unsigned int leaf_data_end(const struct extent_buffer *leaf)
58{
59 u32 nr = btrfs_header_nritems(leaf);
60
61 if (nr == 0)
62 return BTRFS_LEAF_DATA_SIZE(leaf->fs_info);
63 return btrfs_item_offset(leaf, nr - 1);
64}
65
66/*
67 * Move data in a @leaf (using memmove, safe for overlapping ranges).
68 *
69 * @leaf: leaf that we're doing a memmove on
70 * @dst_offset: item data offset we're moving to
71 * @src_offset: item data offset were' moving from
72 * @len: length of the data we're moving
73 *
74 * Wrapper around memmove_extent_buffer() that takes into account the header on
75 * the leaf. The btrfs_item offset's start directly after the header, so we
76 * have to adjust any offsets to account for the header in the leaf. This
77 * handles that math to simplify the callers.
78 */
79static inline void memmove_leaf_data(const struct extent_buffer *leaf,
80 unsigned long dst_offset,
81 unsigned long src_offset,
82 unsigned long len)
83{
84 memmove_extent_buffer(leaf, btrfs_item_nr_offset(leaf, 0) + dst_offset,
85 btrfs_item_nr_offset(leaf, 0) + src_offset, len);
86}
87
88/*
89 * Copy item data from @src into @dst at the given @offset.
90 *
91 * @dst: destination leaf that we're copying into
92 * @src: source leaf that we're copying from
93 * @dst_offset: item data offset we're copying to
94 * @src_offset: item data offset were' copying from
95 * @len: length of the data we're copying
96 *
97 * Wrapper around copy_extent_buffer() that takes into account the header on
98 * the leaf. The btrfs_item offset's start directly after the header, so we
99 * have to adjust any offsets to account for the header in the leaf. This
100 * handles that math to simplify the callers.
101 */
102static inline void copy_leaf_data(const struct extent_buffer *dst,
103 const struct extent_buffer *src,
104 unsigned long dst_offset,
105 unsigned long src_offset, unsigned long len)
106{
107 copy_extent_buffer(dst, src, btrfs_item_nr_offset(dst, 0) + dst_offset,
108 btrfs_item_nr_offset(src, 0) + src_offset, len);
109}
110
111/*
112 * Move items in a @leaf (using memmove).
113 *
114 * @dst: destination leaf for the items
115 * @dst_item: the item nr we're copying into
116 * @src_item: the item nr we're copying from
117 * @nr_items: the number of items to copy
118 *
119 * Wrapper around memmove_extent_buffer() that does the math to get the
120 * appropriate offsets into the leaf from the item numbers.
121 */
122static inline void memmove_leaf_items(const struct extent_buffer *leaf,
123 int dst_item, int src_item, int nr_items)
124{
125 memmove_extent_buffer(leaf, btrfs_item_nr_offset(leaf, dst_item),
126 btrfs_item_nr_offset(leaf, src_item),
127 nr_items * sizeof(struct btrfs_item));
128}
129
130/*
131 * Copy items from @src into @dst at the given @offset.
132 *
133 * @dst: destination leaf for the items
134 * @src: source leaf for the items
135 * @dst_item: the item nr we're copying into
136 * @src_item: the item nr we're copying from
137 * @nr_items: the number of items to copy
138 *
139 * Wrapper around copy_extent_buffer() that does the math to get the
140 * appropriate offsets into the leaf from the item numbers.
141 */
142static inline void copy_leaf_items(const struct extent_buffer *dst,
143 const struct extent_buffer *src,
144 int dst_item, int src_item, int nr_items)
145{
146 copy_extent_buffer(dst, src, btrfs_item_nr_offset(dst, dst_item),
147 btrfs_item_nr_offset(src, src_item),
148 nr_items * sizeof(struct btrfs_item));
149}
150
151/* This exists for btrfs-progs usages. */
152u16 btrfs_csum_type_size(u16 type)
153{
154 return btrfs_csums[type].size;
155}
156
157int btrfs_super_csum_size(const struct btrfs_super_block *s)
158{
159 u16 t = btrfs_super_csum_type(s);
160 /*
161 * csum type is validated at mount time
162 */
163 return btrfs_csum_type_size(t);
164}
165
166const char *btrfs_super_csum_name(u16 csum_type)
167{
168 /* csum type is validated at mount time */
169 return btrfs_csums[csum_type].name;
170}
171
172/*
173 * Return driver name if defined, otherwise the name that's also a valid driver
174 * name
175 */
176const char *btrfs_super_csum_driver(u16 csum_type)
177{
178 /* csum type is validated at mount time */
179 return btrfs_csums[csum_type].driver[0] ?
180 btrfs_csums[csum_type].driver :
181 btrfs_csums[csum_type].name;
182}
183
184size_t __attribute_const__ btrfs_get_num_csums(void)
185{
186 return ARRAY_SIZE(btrfs_csums);
187}
188
189struct btrfs_path *btrfs_alloc_path(void)
190{
191 might_sleep();
192
193 return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
194}
195
196/* this also releases the path */
197void btrfs_free_path(struct btrfs_path *p)
198{
199 if (!p)
200 return;
201 btrfs_release_path(p);
202 kmem_cache_free(btrfs_path_cachep, p);
203}
204
205/*
206 * path release drops references on the extent buffers in the path
207 * and it drops any locks held by this path
208 *
209 * It is safe to call this on paths that no locks or extent buffers held.
210 */
211noinline void btrfs_release_path(struct btrfs_path *p)
212{
213 int i;
214
215 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
216 p->slots[i] = 0;
217 if (!p->nodes[i])
218 continue;
219 if (p->locks[i]) {
220 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
221 p->locks[i] = 0;
222 }
223 free_extent_buffer(p->nodes[i]);
224 p->nodes[i] = NULL;
225 }
226}
227
228/*
229 * We want the transaction abort to print stack trace only for errors where the
230 * cause could be a bug, eg. due to ENOSPC, and not for common errors that are
231 * caused by external factors.
232 */
233bool __cold abort_should_print_stack(int error)
234{
235 switch (error) {
236 case -EIO:
237 case -EROFS:
238 case -ENOMEM:
239 return false;
240 }
241 return true;
242}
243
244/*
245 * safely gets a reference on the root node of a tree. A lock
246 * is not taken, so a concurrent writer may put a different node
247 * at the root of the tree. See btrfs_lock_root_node for the
248 * looping required.
249 *
250 * The extent buffer returned by this has a reference taken, so
251 * it won't disappear. It may stop being the root of the tree
252 * at any time because there are no locks held.
253 */
254struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
255{
256 struct extent_buffer *eb;
257
258 while (1) {
259 rcu_read_lock();
260 eb = rcu_dereference(root->node);
261
262 /*
263 * RCU really hurts here, we could free up the root node because
264 * it was COWed but we may not get the new root node yet so do
265 * the inc_not_zero dance and if it doesn't work then
266 * synchronize_rcu and try again.
267 */
268 if (atomic_inc_not_zero(&eb->refs)) {
269 rcu_read_unlock();
270 break;
271 }
272 rcu_read_unlock();
273 synchronize_rcu();
274 }
275 return eb;
276}
277
278/*
279 * Cowonly root (not-shareable trees, everything not subvolume or reloc roots),
280 * just get put onto a simple dirty list. Transaction walks this list to make
281 * sure they get properly updated on disk.
282 */
283static void add_root_to_dirty_list(struct btrfs_root *root)
284{
285 struct btrfs_fs_info *fs_info = root->fs_info;
286
287 if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
288 !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
289 return;
290
291 spin_lock(&fs_info->trans_lock);
292 if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
293 /* Want the extent tree to be the last on the list */
294 if (btrfs_root_id(root) == BTRFS_EXTENT_TREE_OBJECTID)
295 list_move_tail(&root->dirty_list,
296 &fs_info->dirty_cowonly_roots);
297 else
298 list_move(&root->dirty_list,
299 &fs_info->dirty_cowonly_roots);
300 }
301 spin_unlock(&fs_info->trans_lock);
302}
303
304/*
305 * used by snapshot creation to make a copy of a root for a tree with
306 * a given objectid. The buffer with the new root node is returned in
307 * cow_ret, and this func returns zero on success or a negative error code.
308 */
309int btrfs_copy_root(struct btrfs_trans_handle *trans,
310 struct btrfs_root *root,
311 struct extent_buffer *buf,
312 struct extent_buffer **cow_ret, u64 new_root_objectid)
313{
314 struct btrfs_fs_info *fs_info = root->fs_info;
315 struct extent_buffer *cow;
316 int ret = 0;
317 int level;
318 struct btrfs_disk_key disk_key;
319 u64 reloc_src_root = 0;
320
321 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
322 trans->transid != fs_info->running_transaction->transid);
323 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
324 trans->transid != btrfs_get_root_last_trans(root));
325
326 level = btrfs_header_level(buf);
327 if (level == 0)
328 btrfs_item_key(buf, &disk_key, 0);
329 else
330 btrfs_node_key(buf, &disk_key, 0);
331
332 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
333 reloc_src_root = btrfs_header_owner(buf);
334 cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
335 &disk_key, level, buf->start, 0,
336 reloc_src_root, BTRFS_NESTING_NEW_ROOT);
337 if (IS_ERR(cow))
338 return PTR_ERR(cow);
339
340 copy_extent_buffer_full(cow, buf);
341 btrfs_set_header_bytenr(cow, cow->start);
342 btrfs_set_header_generation(cow, trans->transid);
343 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
344 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
345 BTRFS_HEADER_FLAG_RELOC);
346 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
347 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
348 else
349 btrfs_set_header_owner(cow, new_root_objectid);
350
351 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
352
353 WARN_ON(btrfs_header_generation(buf) > trans->transid);
354 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
355 ret = btrfs_inc_ref(trans, root, cow, 1);
356 else
357 ret = btrfs_inc_ref(trans, root, cow, 0);
358 if (ret) {
359 btrfs_tree_unlock(cow);
360 free_extent_buffer(cow);
361 btrfs_abort_transaction(trans, ret);
362 return ret;
363 }
364
365 btrfs_mark_buffer_dirty(trans, cow);
366 *cow_ret = cow;
367 return 0;
368}
369
370/*
371 * check if the tree block can be shared by multiple trees
372 */
373bool btrfs_block_can_be_shared(struct btrfs_trans_handle *trans,
374 struct btrfs_root *root,
375 struct extent_buffer *buf)
376{
377 const u64 buf_gen = btrfs_header_generation(buf);
378
379 /*
380 * Tree blocks not in shareable trees and tree roots are never shared.
381 * If a block was allocated after the last snapshot and the block was
382 * not allocated by tree relocation, we know the block is not shared.
383 */
384
385 if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
386 return false;
387
388 if (buf == root->node)
389 return false;
390
391 if (buf_gen > btrfs_root_last_snapshot(&root->root_item) &&
392 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))
393 return false;
394
395 if (buf != root->commit_root)
396 return true;
397
398 /*
399 * An extent buffer that used to be the commit root may still be shared
400 * because the tree height may have increased and it became a child of a
401 * higher level root. This can happen when snapshotting a subvolume
402 * created in the current transaction.
403 */
404 if (buf_gen == trans->transid)
405 return true;
406
407 return false;
408}
409
410static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
411 struct btrfs_root *root,
412 struct extent_buffer *buf,
413 struct extent_buffer *cow,
414 int *last_ref)
415{
416 struct btrfs_fs_info *fs_info = root->fs_info;
417 u64 refs;
418 u64 owner;
419 u64 flags;
420 int ret;
421
422 /*
423 * Backrefs update rules:
424 *
425 * Always use full backrefs for extent pointers in tree block
426 * allocated by tree relocation.
427 *
428 * If a shared tree block is no longer referenced by its owner
429 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
430 * use full backrefs for extent pointers in tree block.
431 *
432 * If a tree block is been relocating
433 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
434 * use full backrefs for extent pointers in tree block.
435 * The reason for this is some operations (such as drop tree)
436 * are only allowed for blocks use full backrefs.
437 */
438
439 if (btrfs_block_can_be_shared(trans, root, buf)) {
440 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
441 btrfs_header_level(buf), 1,
442 &refs, &flags, NULL);
443 if (ret)
444 return ret;
445 if (unlikely(refs == 0)) {
446 btrfs_crit(fs_info,
447 "found 0 references for tree block at bytenr %llu level %d root %llu",
448 buf->start, btrfs_header_level(buf),
449 btrfs_root_id(root));
450 ret = -EUCLEAN;
451 btrfs_abort_transaction(trans, ret);
452 return ret;
453 }
454 } else {
455 refs = 1;
456 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID ||
457 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
458 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
459 else
460 flags = 0;
461 }
462
463 owner = btrfs_header_owner(buf);
464 if (unlikely(owner == BTRFS_TREE_RELOC_OBJECTID &&
465 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF))) {
466 btrfs_crit(fs_info,
467"found tree block at bytenr %llu level %d root %llu refs %llu flags %llx without full backref flag set",
468 buf->start, btrfs_header_level(buf),
469 btrfs_root_id(root), refs, flags);
470 ret = -EUCLEAN;
471 btrfs_abort_transaction(trans, ret);
472 return ret;
473 }
474
475 if (refs > 1) {
476 if ((owner == btrfs_root_id(root) ||
477 btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) &&
478 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
479 ret = btrfs_inc_ref(trans, root, buf, 1);
480 if (ret)
481 return ret;
482
483 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) {
484 ret = btrfs_dec_ref(trans, root, buf, 0);
485 if (ret)
486 return ret;
487 ret = btrfs_inc_ref(trans, root, cow, 1);
488 if (ret)
489 return ret;
490 }
491 ret = btrfs_set_disk_extent_flags(trans, buf,
492 BTRFS_BLOCK_FLAG_FULL_BACKREF);
493 if (ret)
494 return ret;
495 } else {
496
497 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
498 ret = btrfs_inc_ref(trans, root, cow, 1);
499 else
500 ret = btrfs_inc_ref(trans, root, cow, 0);
501 if (ret)
502 return ret;
503 }
504 } else {
505 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
506 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
507 ret = btrfs_inc_ref(trans, root, cow, 1);
508 else
509 ret = btrfs_inc_ref(trans, root, cow, 0);
510 if (ret)
511 return ret;
512 ret = btrfs_dec_ref(trans, root, buf, 1);
513 if (ret)
514 return ret;
515 }
516 btrfs_clear_buffer_dirty(trans, buf);
517 *last_ref = 1;
518 }
519 return 0;
520}
521
522/*
523 * does the dirty work in cow of a single block. The parent block (if
524 * supplied) is updated to point to the new cow copy. The new buffer is marked
525 * dirty and returned locked. If you modify the block it needs to be marked
526 * dirty again.
527 *
528 * search_start -- an allocation hint for the new block
529 *
530 * empty_size -- a hint that you plan on doing more cow. This is the size in
531 * bytes the allocator should try to find free next to the block it returns.
532 * This is just a hint and may be ignored by the allocator.
533 */
534int btrfs_force_cow_block(struct btrfs_trans_handle *trans,
535 struct btrfs_root *root,
536 struct extent_buffer *buf,
537 struct extent_buffer *parent, int parent_slot,
538 struct extent_buffer **cow_ret,
539 u64 search_start, u64 empty_size,
540 enum btrfs_lock_nesting nest)
541{
542 struct btrfs_fs_info *fs_info = root->fs_info;
543 struct btrfs_disk_key disk_key;
544 struct extent_buffer *cow;
545 int level, ret;
546 int last_ref = 0;
547 int unlock_orig = 0;
548 u64 parent_start = 0;
549 u64 reloc_src_root = 0;
550
551 if (*cow_ret == buf)
552 unlock_orig = 1;
553
554 btrfs_assert_tree_write_locked(buf);
555
556 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
557 trans->transid != fs_info->running_transaction->transid);
558 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
559 trans->transid != btrfs_get_root_last_trans(root));
560
561 level = btrfs_header_level(buf);
562
563 if (level == 0)
564 btrfs_item_key(buf, &disk_key, 0);
565 else
566 btrfs_node_key(buf, &disk_key, 0);
567
568 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID) {
569 if (parent)
570 parent_start = parent->start;
571 reloc_src_root = btrfs_header_owner(buf);
572 }
573 cow = btrfs_alloc_tree_block(trans, root, parent_start,
574 btrfs_root_id(root), &disk_key, level,
575 search_start, empty_size, reloc_src_root, nest);
576 if (IS_ERR(cow))
577 return PTR_ERR(cow);
578
579 /* cow is set to blocking by btrfs_init_new_buffer */
580
581 copy_extent_buffer_full(cow, buf);
582 btrfs_set_header_bytenr(cow, cow->start);
583 btrfs_set_header_generation(cow, trans->transid);
584 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
585 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
586 BTRFS_HEADER_FLAG_RELOC);
587 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
588 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
589 else
590 btrfs_set_header_owner(cow, btrfs_root_id(root));
591
592 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
593
594 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
595 if (ret) {
596 btrfs_abort_transaction(trans, ret);
597 goto error_unlock_cow;
598 }
599
600 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
601 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
602 if (ret) {
603 btrfs_abort_transaction(trans, ret);
604 goto error_unlock_cow;
605 }
606 }
607
608 if (buf == root->node) {
609 WARN_ON(parent && parent != buf);
610 if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID ||
611 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
612 parent_start = buf->start;
613
614 ret = btrfs_tree_mod_log_insert_root(root->node, cow, true);
615 if (ret < 0) {
616 btrfs_abort_transaction(trans, ret);
617 goto error_unlock_cow;
618 }
619 atomic_inc(&cow->refs);
620 rcu_assign_pointer(root->node, cow);
621
622 ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
623 parent_start, last_ref);
624 free_extent_buffer(buf);
625 add_root_to_dirty_list(root);
626 if (ret < 0) {
627 btrfs_abort_transaction(trans, ret);
628 goto error_unlock_cow;
629 }
630 } else {
631 WARN_ON(trans->transid != btrfs_header_generation(parent));
632 ret = btrfs_tree_mod_log_insert_key(parent, parent_slot,
633 BTRFS_MOD_LOG_KEY_REPLACE);
634 if (ret) {
635 btrfs_abort_transaction(trans, ret);
636 goto error_unlock_cow;
637 }
638 btrfs_set_node_blockptr(parent, parent_slot,
639 cow->start);
640 btrfs_set_node_ptr_generation(parent, parent_slot,
641 trans->transid);
642 btrfs_mark_buffer_dirty(trans, parent);
643 if (last_ref) {
644 ret = btrfs_tree_mod_log_free_eb(buf);
645 if (ret) {
646 btrfs_abort_transaction(trans, ret);
647 goto error_unlock_cow;
648 }
649 }
650 ret = btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
651 parent_start, last_ref);
652 if (ret < 0) {
653 btrfs_abort_transaction(trans, ret);
654 goto error_unlock_cow;
655 }
656 }
657
658 trace_btrfs_cow_block(root, buf, cow);
659 if (unlock_orig)
660 btrfs_tree_unlock(buf);
661 free_extent_buffer_stale(buf);
662 btrfs_mark_buffer_dirty(trans, cow);
663 *cow_ret = cow;
664 return 0;
665
666error_unlock_cow:
667 btrfs_tree_unlock(cow);
668 free_extent_buffer(cow);
669 return ret;
670}
671
672static inline int should_cow_block(struct btrfs_trans_handle *trans,
673 struct btrfs_root *root,
674 struct extent_buffer *buf)
675{
676 if (btrfs_is_testing(root->fs_info))
677 return 0;
678
679 /* Ensure we can see the FORCE_COW bit */
680 smp_mb__before_atomic();
681
682 /*
683 * We do not need to cow a block if
684 * 1) this block is not created or changed in this transaction;
685 * 2) this block does not belong to TREE_RELOC tree;
686 * 3) the root is not forced COW.
687 *
688 * What is forced COW:
689 * when we create snapshot during committing the transaction,
690 * after we've finished copying src root, we must COW the shared
691 * block to ensure the metadata consistency.
692 */
693 if (btrfs_header_generation(buf) == trans->transid &&
694 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
695 !(btrfs_root_id(root) != BTRFS_TREE_RELOC_OBJECTID &&
696 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
697 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
698 return 0;
699 return 1;
700}
701
702/*
703 * COWs a single block, see btrfs_force_cow_block() for the real work.
704 * This version of it has extra checks so that a block isn't COWed more than
705 * once per transaction, as long as it hasn't been written yet
706 */
707int btrfs_cow_block(struct btrfs_trans_handle *trans,
708 struct btrfs_root *root, struct extent_buffer *buf,
709 struct extent_buffer *parent, int parent_slot,
710 struct extent_buffer **cow_ret,
711 enum btrfs_lock_nesting nest)
712{
713 struct btrfs_fs_info *fs_info = root->fs_info;
714 u64 search_start;
715
716 if (unlikely(test_bit(BTRFS_ROOT_DELETING, &root->state))) {
717 btrfs_abort_transaction(trans, -EUCLEAN);
718 btrfs_crit(fs_info,
719 "attempt to COW block %llu on root %llu that is being deleted",
720 buf->start, btrfs_root_id(root));
721 return -EUCLEAN;
722 }
723
724 /*
725 * COWing must happen through a running transaction, which always
726 * matches the current fs generation (it's a transaction with a state
727 * less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs
728 * into error state to prevent the commit of any transaction.
729 */
730 if (unlikely(trans->transaction != fs_info->running_transaction ||
731 trans->transid != fs_info->generation)) {
732 btrfs_abort_transaction(trans, -EUCLEAN);
733 btrfs_crit(fs_info,
734"unexpected transaction when attempting to COW block %llu on root %llu, transaction %llu running transaction %llu fs generation %llu",
735 buf->start, btrfs_root_id(root), trans->transid,
736 fs_info->running_transaction->transid,
737 fs_info->generation);
738 return -EUCLEAN;
739 }
740
741 if (!should_cow_block(trans, root, buf)) {
742 *cow_ret = buf;
743 return 0;
744 }
745
746 search_start = round_down(buf->start, SZ_1G);
747
748 /*
749 * Before CoWing this block for later modification, check if it's
750 * the subtree root and do the delayed subtree trace if needed.
751 *
752 * Also We don't care about the error, as it's handled internally.
753 */
754 btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
755 return btrfs_force_cow_block(trans, root, buf, parent, parent_slot,
756 cow_ret, search_start, 0, nest);
757}
758ALLOW_ERROR_INJECTION(btrfs_cow_block, ERRNO);
759
760/*
761 * same as comp_keys only with two btrfs_key's
762 */
763int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
764{
765 if (k1->objectid > k2->objectid)
766 return 1;
767 if (k1->objectid < k2->objectid)
768 return -1;
769 if (k1->type > k2->type)
770 return 1;
771 if (k1->type < k2->type)
772 return -1;
773 if (k1->offset > k2->offset)
774 return 1;
775 if (k1->offset < k2->offset)
776 return -1;
777 return 0;
778}
779
780/*
781 * Search for a key in the given extent_buffer.
782 *
783 * The lower boundary for the search is specified by the slot number @first_slot.
784 * Use a value of 0 to search over the whole extent buffer. Works for both
785 * leaves and nodes.
786 *
787 * The slot in the extent buffer is returned via @slot. If the key exists in the
788 * extent buffer, then @slot will point to the slot where the key is, otherwise
789 * it points to the slot where you would insert the key.
790 *
791 * Slot may point to the total number of items (i.e. one position beyond the last
792 * key) if the key is bigger than the last key in the extent buffer.
793 */
794int btrfs_bin_search(struct extent_buffer *eb, int first_slot,
795 const struct btrfs_key *key, int *slot)
796{
797 unsigned long p;
798 int item_size;
799 /*
800 * Use unsigned types for the low and high slots, so that we get a more
801 * efficient division in the search loop below.
802 */
803 u32 low = first_slot;
804 u32 high = btrfs_header_nritems(eb);
805 int ret;
806 const int key_size = sizeof(struct btrfs_disk_key);
807
808 if (unlikely(low > high)) {
809 btrfs_err(eb->fs_info,
810 "%s: low (%u) > high (%u) eb %llu owner %llu level %d",
811 __func__, low, high, eb->start,
812 btrfs_header_owner(eb), btrfs_header_level(eb));
813 return -EINVAL;
814 }
815
816 if (btrfs_header_level(eb) == 0) {
817 p = offsetof(struct btrfs_leaf, items);
818 item_size = sizeof(struct btrfs_item);
819 } else {
820 p = offsetof(struct btrfs_node, ptrs);
821 item_size = sizeof(struct btrfs_key_ptr);
822 }
823
824 while (low < high) {
825 const int unit_size = eb->folio_size;
826 unsigned long oil;
827 unsigned long offset;
828 struct btrfs_disk_key *tmp;
829 struct btrfs_disk_key unaligned;
830 int mid;
831
832 mid = (low + high) / 2;
833 offset = p + mid * item_size;
834 oil = get_eb_offset_in_folio(eb, offset);
835
836 if (oil + key_size <= unit_size) {
837 const unsigned long idx = get_eb_folio_index(eb, offset);
838 char *kaddr = folio_address(eb->folios[idx]);
839
840 oil = get_eb_offset_in_folio(eb, offset);
841 tmp = (struct btrfs_disk_key *)(kaddr + oil);
842 } else {
843 read_extent_buffer(eb, &unaligned, offset, key_size);
844 tmp = &unaligned;
845 }
846
847 ret = btrfs_comp_keys(tmp, key);
848
849 if (ret < 0)
850 low = mid + 1;
851 else if (ret > 0)
852 high = mid;
853 else {
854 *slot = mid;
855 return 0;
856 }
857 }
858 *slot = low;
859 return 1;
860}
861
862static void root_add_used_bytes(struct btrfs_root *root)
863{
864 spin_lock(&root->accounting_lock);
865 btrfs_set_root_used(&root->root_item,
866 btrfs_root_used(&root->root_item) + root->fs_info->nodesize);
867 spin_unlock(&root->accounting_lock);
868}
869
870static void root_sub_used_bytes(struct btrfs_root *root)
871{
872 spin_lock(&root->accounting_lock);
873 btrfs_set_root_used(&root->root_item,
874 btrfs_root_used(&root->root_item) - root->fs_info->nodesize);
875 spin_unlock(&root->accounting_lock);
876}
877
878/* given a node and slot number, this reads the blocks it points to. The
879 * extent buffer is returned with a reference taken (but unlocked).
880 */
881struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
882 int slot)
883{
884 int level = btrfs_header_level(parent);
885 struct btrfs_tree_parent_check check = { 0 };
886 struct extent_buffer *eb;
887
888 if (slot < 0 || slot >= btrfs_header_nritems(parent))
889 return ERR_PTR(-ENOENT);
890
891 ASSERT(level);
892
893 check.level = level - 1;
894 check.transid = btrfs_node_ptr_generation(parent, slot);
895 check.owner_root = btrfs_header_owner(parent);
896 check.has_first_key = true;
897 btrfs_node_key_to_cpu(parent, &check.first_key, slot);
898
899 eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
900 &check);
901 if (IS_ERR(eb))
902 return eb;
903 if (!extent_buffer_uptodate(eb)) {
904 free_extent_buffer(eb);
905 return ERR_PTR(-EIO);
906 }
907
908 return eb;
909}
910
911/*
912 * node level balancing, used to make sure nodes are in proper order for
913 * item deletion. We balance from the top down, so we have to make sure
914 * that a deletion won't leave an node completely empty later on.
915 */
916static noinline int balance_level(struct btrfs_trans_handle *trans,
917 struct btrfs_root *root,
918 struct btrfs_path *path, int level)
919{
920 struct btrfs_fs_info *fs_info = root->fs_info;
921 struct extent_buffer *right = NULL;
922 struct extent_buffer *mid;
923 struct extent_buffer *left = NULL;
924 struct extent_buffer *parent = NULL;
925 int ret = 0;
926 int wret;
927 int pslot;
928 int orig_slot = path->slots[level];
929 u64 orig_ptr;
930
931 ASSERT(level > 0);
932
933 mid = path->nodes[level];
934
935 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK);
936 WARN_ON(btrfs_header_generation(mid) != trans->transid);
937
938 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
939
940 if (level < BTRFS_MAX_LEVEL - 1) {
941 parent = path->nodes[level + 1];
942 pslot = path->slots[level + 1];
943 }
944
945 /*
946 * deal with the case where there is only one pointer in the root
947 * by promoting the node below to a root
948 */
949 if (!parent) {
950 struct extent_buffer *child;
951
952 if (btrfs_header_nritems(mid) != 1)
953 return 0;
954
955 /* promote the child to a root */
956 child = btrfs_read_node_slot(mid, 0);
957 if (IS_ERR(child)) {
958 ret = PTR_ERR(child);
959 goto out;
960 }
961
962 btrfs_tree_lock(child);
963 ret = btrfs_cow_block(trans, root, child, mid, 0, &child,
964 BTRFS_NESTING_COW);
965 if (ret) {
966 btrfs_tree_unlock(child);
967 free_extent_buffer(child);
968 goto out;
969 }
970
971 ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
972 if (ret < 0) {
973 btrfs_tree_unlock(child);
974 free_extent_buffer(child);
975 btrfs_abort_transaction(trans, ret);
976 goto out;
977 }
978 rcu_assign_pointer(root->node, child);
979
980 add_root_to_dirty_list(root);
981 btrfs_tree_unlock(child);
982
983 path->locks[level] = 0;
984 path->nodes[level] = NULL;
985 btrfs_clear_buffer_dirty(trans, mid);
986 btrfs_tree_unlock(mid);
987 /* once for the path */
988 free_extent_buffer(mid);
989
990 root_sub_used_bytes(root);
991 ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
992 /* once for the root ptr */
993 free_extent_buffer_stale(mid);
994 if (ret < 0) {
995 btrfs_abort_transaction(trans, ret);
996 goto out;
997 }
998 return 0;
999 }
1000 if (btrfs_header_nritems(mid) >
1001 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
1002 return 0;
1003
1004 if (pslot) {
1005 left = btrfs_read_node_slot(parent, pslot - 1);
1006 if (IS_ERR(left)) {
1007 ret = PTR_ERR(left);
1008 left = NULL;
1009 goto out;
1010 }
1011
1012 btrfs_tree_lock_nested(left, BTRFS_NESTING_LEFT);
1013 wret = btrfs_cow_block(trans, root, left,
1014 parent, pslot - 1, &left,
1015 BTRFS_NESTING_LEFT_COW);
1016 if (wret) {
1017 ret = wret;
1018 goto out;
1019 }
1020 }
1021
1022 if (pslot + 1 < btrfs_header_nritems(parent)) {
1023 right = btrfs_read_node_slot(parent, pslot + 1);
1024 if (IS_ERR(right)) {
1025 ret = PTR_ERR(right);
1026 right = NULL;
1027 goto out;
1028 }
1029
1030 btrfs_tree_lock_nested(right, BTRFS_NESTING_RIGHT);
1031 wret = btrfs_cow_block(trans, root, right,
1032 parent, pslot + 1, &right,
1033 BTRFS_NESTING_RIGHT_COW);
1034 if (wret) {
1035 ret = wret;
1036 goto out;
1037 }
1038 }
1039
1040 /* first, try to make some room in the middle buffer */
1041 if (left) {
1042 orig_slot += btrfs_header_nritems(left);
1043 wret = push_node_left(trans, left, mid, 1);
1044 if (wret < 0)
1045 ret = wret;
1046 }
1047
1048 /*
1049 * then try to empty the right most buffer into the middle
1050 */
1051 if (right) {
1052 wret = push_node_left(trans, mid, right, 1);
1053 if (wret < 0 && wret != -ENOSPC)
1054 ret = wret;
1055 if (btrfs_header_nritems(right) == 0) {
1056 btrfs_clear_buffer_dirty(trans, right);
1057 btrfs_tree_unlock(right);
1058 ret = btrfs_del_ptr(trans, root, path, level + 1, pslot + 1);
1059 if (ret < 0) {
1060 free_extent_buffer_stale(right);
1061 right = NULL;
1062 goto out;
1063 }
1064 root_sub_used_bytes(root);
1065 ret = btrfs_free_tree_block(trans, btrfs_root_id(root),
1066 right, 0, 1);
1067 free_extent_buffer_stale(right);
1068 right = NULL;
1069 if (ret < 0) {
1070 btrfs_abort_transaction(trans, ret);
1071 goto out;
1072 }
1073 } else {
1074 struct btrfs_disk_key right_key;
1075 btrfs_node_key(right, &right_key, 0);
1076 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1077 BTRFS_MOD_LOG_KEY_REPLACE);
1078 if (ret < 0) {
1079 btrfs_abort_transaction(trans, ret);
1080 goto out;
1081 }
1082 btrfs_set_node_key(parent, &right_key, pslot + 1);
1083 btrfs_mark_buffer_dirty(trans, parent);
1084 }
1085 }
1086 if (btrfs_header_nritems(mid) == 1) {
1087 /*
1088 * we're not allowed to leave a node with one item in the
1089 * tree during a delete. A deletion from lower in the tree
1090 * could try to delete the only pointer in this node.
1091 * So, pull some keys from the left.
1092 * There has to be a left pointer at this point because
1093 * otherwise we would have pulled some pointers from the
1094 * right
1095 */
1096 if (unlikely(!left)) {
1097 btrfs_crit(fs_info,
1098"missing left child when middle child only has 1 item, parent bytenr %llu level %d mid bytenr %llu root %llu",
1099 parent->start, btrfs_header_level(parent),
1100 mid->start, btrfs_root_id(root));
1101 ret = -EUCLEAN;
1102 btrfs_abort_transaction(trans, ret);
1103 goto out;
1104 }
1105 wret = balance_node_right(trans, mid, left);
1106 if (wret < 0) {
1107 ret = wret;
1108 goto out;
1109 }
1110 if (wret == 1) {
1111 wret = push_node_left(trans, left, mid, 1);
1112 if (wret < 0)
1113 ret = wret;
1114 }
1115 BUG_ON(wret == 1);
1116 }
1117 if (btrfs_header_nritems(mid) == 0) {
1118 btrfs_clear_buffer_dirty(trans, mid);
1119 btrfs_tree_unlock(mid);
1120 ret = btrfs_del_ptr(trans, root, path, level + 1, pslot);
1121 if (ret < 0) {
1122 free_extent_buffer_stale(mid);
1123 mid = NULL;
1124 goto out;
1125 }
1126 root_sub_used_bytes(root);
1127 ret = btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
1128 free_extent_buffer_stale(mid);
1129 mid = NULL;
1130 if (ret < 0) {
1131 btrfs_abort_transaction(trans, ret);
1132 goto out;
1133 }
1134 } else {
1135 /* update the parent key to reflect our changes */
1136 struct btrfs_disk_key mid_key;
1137 btrfs_node_key(mid, &mid_key, 0);
1138 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1139 BTRFS_MOD_LOG_KEY_REPLACE);
1140 if (ret < 0) {
1141 btrfs_abort_transaction(trans, ret);
1142 goto out;
1143 }
1144 btrfs_set_node_key(parent, &mid_key, pslot);
1145 btrfs_mark_buffer_dirty(trans, parent);
1146 }
1147
1148 /* update the path */
1149 if (left) {
1150 if (btrfs_header_nritems(left) > orig_slot) {
1151 atomic_inc(&left->refs);
1152 /* left was locked after cow */
1153 path->nodes[level] = left;
1154 path->slots[level + 1] -= 1;
1155 path->slots[level] = orig_slot;
1156 if (mid) {
1157 btrfs_tree_unlock(mid);
1158 free_extent_buffer(mid);
1159 }
1160 } else {
1161 orig_slot -= btrfs_header_nritems(left);
1162 path->slots[level] = orig_slot;
1163 }
1164 }
1165 /* double check we haven't messed things up */
1166 if (orig_ptr !=
1167 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1168 BUG();
1169out:
1170 if (right) {
1171 btrfs_tree_unlock(right);
1172 free_extent_buffer(right);
1173 }
1174 if (left) {
1175 if (path->nodes[level] != left)
1176 btrfs_tree_unlock(left);
1177 free_extent_buffer(left);
1178 }
1179 return ret;
1180}
1181
1182/* Node balancing for insertion. Here we only split or push nodes around
1183 * when they are completely full. This is also done top down, so we
1184 * have to be pessimistic.
1185 */
1186static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1187 struct btrfs_root *root,
1188 struct btrfs_path *path, int level)
1189{
1190 struct btrfs_fs_info *fs_info = root->fs_info;
1191 struct extent_buffer *right = NULL;
1192 struct extent_buffer *mid;
1193 struct extent_buffer *left = NULL;
1194 struct extent_buffer *parent = NULL;
1195 int ret = 0;
1196 int wret;
1197 int pslot;
1198 int orig_slot = path->slots[level];
1199
1200 if (level == 0)
1201 return 1;
1202
1203 mid = path->nodes[level];
1204 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1205
1206 if (level < BTRFS_MAX_LEVEL - 1) {
1207 parent = path->nodes[level + 1];
1208 pslot = path->slots[level + 1];
1209 }
1210
1211 if (!parent)
1212 return 1;
1213
1214 /* first, try to make some room in the middle buffer */
1215 if (pslot) {
1216 u32 left_nr;
1217
1218 left = btrfs_read_node_slot(parent, pslot - 1);
1219 if (IS_ERR(left))
1220 return PTR_ERR(left);
1221
1222 btrfs_tree_lock_nested(left, BTRFS_NESTING_LEFT);
1223
1224 left_nr = btrfs_header_nritems(left);
1225 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1226 wret = 1;
1227 } else {
1228 ret = btrfs_cow_block(trans, root, left, parent,
1229 pslot - 1, &left,
1230 BTRFS_NESTING_LEFT_COW);
1231 if (ret)
1232 wret = 1;
1233 else {
1234 wret = push_node_left(trans, left, mid, 0);
1235 }
1236 }
1237 if (wret < 0)
1238 ret = wret;
1239 if (wret == 0) {
1240 struct btrfs_disk_key disk_key;
1241 orig_slot += left_nr;
1242 btrfs_node_key(mid, &disk_key, 0);
1243 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1244 BTRFS_MOD_LOG_KEY_REPLACE);
1245 if (ret < 0) {
1246 btrfs_tree_unlock(left);
1247 free_extent_buffer(left);
1248 btrfs_abort_transaction(trans, ret);
1249 return ret;
1250 }
1251 btrfs_set_node_key(parent, &disk_key, pslot);
1252 btrfs_mark_buffer_dirty(trans, parent);
1253 if (btrfs_header_nritems(left) > orig_slot) {
1254 path->nodes[level] = left;
1255 path->slots[level + 1] -= 1;
1256 path->slots[level] = orig_slot;
1257 btrfs_tree_unlock(mid);
1258 free_extent_buffer(mid);
1259 } else {
1260 orig_slot -=
1261 btrfs_header_nritems(left);
1262 path->slots[level] = orig_slot;
1263 btrfs_tree_unlock(left);
1264 free_extent_buffer(left);
1265 }
1266 return 0;
1267 }
1268 btrfs_tree_unlock(left);
1269 free_extent_buffer(left);
1270 }
1271
1272 /*
1273 * then try to empty the right most buffer into the middle
1274 */
1275 if (pslot + 1 < btrfs_header_nritems(parent)) {
1276 u32 right_nr;
1277
1278 right = btrfs_read_node_slot(parent, pslot + 1);
1279 if (IS_ERR(right))
1280 return PTR_ERR(right);
1281
1282 btrfs_tree_lock_nested(right, BTRFS_NESTING_RIGHT);
1283
1284 right_nr = btrfs_header_nritems(right);
1285 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1286 wret = 1;
1287 } else {
1288 ret = btrfs_cow_block(trans, root, right,
1289 parent, pslot + 1,
1290 &right, BTRFS_NESTING_RIGHT_COW);
1291 if (ret)
1292 wret = 1;
1293 else {
1294 wret = balance_node_right(trans, right, mid);
1295 }
1296 }
1297 if (wret < 0)
1298 ret = wret;
1299 if (wret == 0) {
1300 struct btrfs_disk_key disk_key;
1301
1302 btrfs_node_key(right, &disk_key, 0);
1303 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1304 BTRFS_MOD_LOG_KEY_REPLACE);
1305 if (ret < 0) {
1306 btrfs_tree_unlock(right);
1307 free_extent_buffer(right);
1308 btrfs_abort_transaction(trans, ret);
1309 return ret;
1310 }
1311 btrfs_set_node_key(parent, &disk_key, pslot + 1);
1312 btrfs_mark_buffer_dirty(trans, parent);
1313
1314 if (btrfs_header_nritems(mid) <= orig_slot) {
1315 path->nodes[level] = right;
1316 path->slots[level + 1] += 1;
1317 path->slots[level] = orig_slot -
1318 btrfs_header_nritems(mid);
1319 btrfs_tree_unlock(mid);
1320 free_extent_buffer(mid);
1321 } else {
1322 btrfs_tree_unlock(right);
1323 free_extent_buffer(right);
1324 }
1325 return 0;
1326 }
1327 btrfs_tree_unlock(right);
1328 free_extent_buffer(right);
1329 }
1330 return 1;
1331}
1332
1333/*
1334 * readahead one full node of leaves, finding things that are close
1335 * to the block in 'slot', and triggering ra on them.
1336 */
1337static void reada_for_search(struct btrfs_fs_info *fs_info,
1338 struct btrfs_path *path,
1339 int level, int slot, u64 objectid)
1340{
1341 struct extent_buffer *node;
1342 struct btrfs_disk_key disk_key;
1343 u32 nritems;
1344 u64 search;
1345 u64 target;
1346 u64 nread = 0;
1347 u64 nread_max;
1348 u32 nr;
1349 u32 blocksize;
1350 u32 nscan = 0;
1351
1352 if (level != 1 && path->reada != READA_FORWARD_ALWAYS)
1353 return;
1354
1355 if (!path->nodes[level])
1356 return;
1357
1358 node = path->nodes[level];
1359
1360 /*
1361 * Since the time between visiting leaves is much shorter than the time
1362 * between visiting nodes, limit read ahead of nodes to 1, to avoid too
1363 * much IO at once (possibly random).
1364 */
1365 if (path->reada == READA_FORWARD_ALWAYS) {
1366 if (level > 1)
1367 nread_max = node->fs_info->nodesize;
1368 else
1369 nread_max = SZ_128K;
1370 } else {
1371 nread_max = SZ_64K;
1372 }
1373
1374 search = btrfs_node_blockptr(node, slot);
1375 blocksize = fs_info->nodesize;
1376 if (path->reada != READA_FORWARD_ALWAYS) {
1377 struct extent_buffer *eb;
1378
1379 eb = find_extent_buffer(fs_info, search);
1380 if (eb) {
1381 free_extent_buffer(eb);
1382 return;
1383 }
1384 }
1385
1386 target = search;
1387
1388 nritems = btrfs_header_nritems(node);
1389 nr = slot;
1390
1391 while (1) {
1392 if (path->reada == READA_BACK) {
1393 if (nr == 0)
1394 break;
1395 nr--;
1396 } else if (path->reada == READA_FORWARD ||
1397 path->reada == READA_FORWARD_ALWAYS) {
1398 nr++;
1399 if (nr >= nritems)
1400 break;
1401 }
1402 if (path->reada == READA_BACK && objectid) {
1403 btrfs_node_key(node, &disk_key, nr);
1404 if (btrfs_disk_key_objectid(&disk_key) != objectid)
1405 break;
1406 }
1407 search = btrfs_node_blockptr(node, nr);
1408 if (path->reada == READA_FORWARD_ALWAYS ||
1409 (search <= target && target - search <= 65536) ||
1410 (search > target && search - target <= 65536)) {
1411 btrfs_readahead_node_child(node, nr);
1412 nread += blocksize;
1413 }
1414 nscan++;
1415 if (nread > nread_max || nscan > 32)
1416 break;
1417 }
1418}
1419
1420static noinline void reada_for_balance(struct btrfs_path *path, int level)
1421{
1422 struct extent_buffer *parent;
1423 int slot;
1424 int nritems;
1425
1426 parent = path->nodes[level + 1];
1427 if (!parent)
1428 return;
1429
1430 nritems = btrfs_header_nritems(parent);
1431 slot = path->slots[level + 1];
1432
1433 if (slot > 0)
1434 btrfs_readahead_node_child(parent, slot - 1);
1435 if (slot + 1 < nritems)
1436 btrfs_readahead_node_child(parent, slot + 1);
1437}
1438
1439
1440/*
1441 * when we walk down the tree, it is usually safe to unlock the higher layers
1442 * in the tree. The exceptions are when our path goes through slot 0, because
1443 * operations on the tree might require changing key pointers higher up in the
1444 * tree.
1445 *
1446 * callers might also have set path->keep_locks, which tells this code to keep
1447 * the lock if the path points to the last slot in the block. This is part of
1448 * walking through the tree, and selecting the next slot in the higher block.
1449 *
1450 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
1451 * if lowest_unlock is 1, level 0 won't be unlocked
1452 */
1453static noinline void unlock_up(struct btrfs_path *path, int level,
1454 int lowest_unlock, int min_write_lock_level,
1455 int *write_lock_level)
1456{
1457 int i;
1458 int skip_level = level;
1459 bool check_skip = true;
1460
1461 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1462 if (!path->nodes[i])
1463 break;
1464 if (!path->locks[i])
1465 break;
1466
1467 if (check_skip) {
1468 if (path->slots[i] == 0) {
1469 skip_level = i + 1;
1470 continue;
1471 }
1472
1473 if (path->keep_locks) {
1474 u32 nritems;
1475
1476 nritems = btrfs_header_nritems(path->nodes[i]);
1477 if (nritems < 1 || path->slots[i] >= nritems - 1) {
1478 skip_level = i + 1;
1479 continue;
1480 }
1481 }
1482 }
1483
1484 if (i >= lowest_unlock && i > skip_level) {
1485 check_skip = false;
1486 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
1487 path->locks[i] = 0;
1488 if (write_lock_level &&
1489 i > min_write_lock_level &&
1490 i <= *write_lock_level) {
1491 *write_lock_level = i - 1;
1492 }
1493 }
1494 }
1495}
1496
1497/*
1498 * Helper function for btrfs_search_slot() and other functions that do a search
1499 * on a btree. The goal is to find a tree block in the cache (the radix tree at
1500 * fs_info->buffer_radix), but if we can't find it, or it's not up to date, read
1501 * its pages from disk.
1502 *
1503 * Returns -EAGAIN, with the path unlocked, if the caller needs to repeat the
1504 * whole btree search, starting again from the current root node.
1505 */
1506static int
1507read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
1508 struct extent_buffer **eb_ret, int slot,
1509 const struct btrfs_key *key)
1510{
1511 struct btrfs_fs_info *fs_info = root->fs_info;
1512 struct btrfs_tree_parent_check check = { 0 };
1513 u64 blocknr;
1514 struct extent_buffer *tmp = NULL;
1515 int ret = 0;
1516 int parent_level;
1517 int err;
1518 bool read_tmp = false;
1519 bool tmp_locked = false;
1520 bool path_released = false;
1521
1522 blocknr = btrfs_node_blockptr(*eb_ret, slot);
1523 parent_level = btrfs_header_level(*eb_ret);
1524 btrfs_node_key_to_cpu(*eb_ret, &check.first_key, slot);
1525 check.has_first_key = true;
1526 check.level = parent_level - 1;
1527 check.transid = btrfs_node_ptr_generation(*eb_ret, slot);
1528 check.owner_root = btrfs_root_id(root);
1529
1530 /*
1531 * If we need to read an extent buffer from disk and we are holding locks
1532 * on upper level nodes, we unlock all the upper nodes before reading the
1533 * extent buffer, and then return -EAGAIN to the caller as it needs to
1534 * restart the search. We don't release the lock on the current level
1535 * because we need to walk this node to figure out which blocks to read.
1536 */
1537 tmp = find_extent_buffer(fs_info, blocknr);
1538 if (tmp) {
1539 if (p->reada == READA_FORWARD_ALWAYS)
1540 reada_for_search(fs_info, p, parent_level, slot, key->objectid);
1541
1542 /* first we do an atomic uptodate check */
1543 if (btrfs_buffer_uptodate(tmp, check.transid, 1) > 0) {
1544 /*
1545 * Do extra check for first_key, eb can be stale due to
1546 * being cached, read from scrub, or have multiple
1547 * parents (shared tree blocks).
1548 */
1549 if (btrfs_verify_level_key(tmp, &check)) {
1550 ret = -EUCLEAN;
1551 goto out;
1552 }
1553 *eb_ret = tmp;
1554 tmp = NULL;
1555 ret = 0;
1556 goto out;
1557 }
1558
1559 if (p->nowait) {
1560 ret = -EAGAIN;
1561 goto out;
1562 }
1563
1564 if (!p->skip_locking) {
1565 btrfs_unlock_up_safe(p, parent_level + 1);
1566 btrfs_maybe_reset_lockdep_class(root, tmp);
1567 tmp_locked = true;
1568 btrfs_tree_read_lock(tmp);
1569 btrfs_release_path(p);
1570 ret = -EAGAIN;
1571 path_released = true;
1572 }
1573
1574 /* Now we're allowed to do a blocking uptodate check. */
1575 err = btrfs_read_extent_buffer(tmp, &check);
1576 if (err) {
1577 ret = err;
1578 goto out;
1579 }
1580
1581 if (ret == 0) {
1582 ASSERT(!tmp_locked);
1583 *eb_ret = tmp;
1584 tmp = NULL;
1585 }
1586 goto out;
1587 } else if (p->nowait) {
1588 ret = -EAGAIN;
1589 goto out;
1590 }
1591
1592 if (!p->skip_locking) {
1593 btrfs_unlock_up_safe(p, parent_level + 1);
1594 ret = -EAGAIN;
1595 }
1596
1597 if (p->reada != READA_NONE)
1598 reada_for_search(fs_info, p, parent_level, slot, key->objectid);
1599
1600 tmp = btrfs_find_create_tree_block(fs_info, blocknr, check.owner_root, check.level);
1601 if (IS_ERR(tmp)) {
1602 ret = PTR_ERR(tmp);
1603 tmp = NULL;
1604 goto out;
1605 }
1606 read_tmp = true;
1607
1608 if (!p->skip_locking) {
1609 ASSERT(ret == -EAGAIN);
1610 btrfs_maybe_reset_lockdep_class(root, tmp);
1611 tmp_locked = true;
1612 btrfs_tree_read_lock(tmp);
1613 btrfs_release_path(p);
1614 path_released = true;
1615 }
1616
1617 /* Now we're allowed to do a blocking uptodate check. */
1618 err = btrfs_read_extent_buffer(tmp, &check);
1619 if (err) {
1620 ret = err;
1621 goto out;
1622 }
1623
1624 /*
1625 * If the read above didn't mark this buffer up to date,
1626 * it will never end up being up to date. Set ret to EIO now
1627 * and give up so that our caller doesn't loop forever
1628 * on our EAGAINs.
1629 */
1630 if (!extent_buffer_uptodate(tmp)) {
1631 ret = -EIO;
1632 goto out;
1633 }
1634
1635 if (ret == 0) {
1636 ASSERT(!tmp_locked);
1637 *eb_ret = tmp;
1638 tmp = NULL;
1639 }
1640out:
1641 if (tmp) {
1642 if (tmp_locked)
1643 btrfs_tree_read_unlock(tmp);
1644 if (read_tmp && ret && ret != -EAGAIN)
1645 free_extent_buffer_stale(tmp);
1646 else
1647 free_extent_buffer(tmp);
1648 }
1649 if (ret && !path_released)
1650 btrfs_release_path(p);
1651
1652 return ret;
1653}
1654
1655/*
1656 * helper function for btrfs_search_slot. This does all of the checks
1657 * for node-level blocks and does any balancing required based on
1658 * the ins_len.
1659 *
1660 * If no extra work was required, zero is returned. If we had to
1661 * drop the path, -EAGAIN is returned and btrfs_search_slot must
1662 * start over
1663 */
1664static int
1665setup_nodes_for_search(struct btrfs_trans_handle *trans,
1666 struct btrfs_root *root, struct btrfs_path *p,
1667 struct extent_buffer *b, int level, int ins_len,
1668 int *write_lock_level)
1669{
1670 struct btrfs_fs_info *fs_info = root->fs_info;
1671 int ret = 0;
1672
1673 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
1674 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
1675
1676 if (*write_lock_level < level + 1) {
1677 *write_lock_level = level + 1;
1678 btrfs_release_path(p);
1679 return -EAGAIN;
1680 }
1681
1682 reada_for_balance(p, level);
1683 ret = split_node(trans, root, p, level);
1684
1685 b = p->nodes[level];
1686 } else if (ins_len < 0 && btrfs_header_nritems(b) <
1687 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
1688
1689 if (*write_lock_level < level + 1) {
1690 *write_lock_level = level + 1;
1691 btrfs_release_path(p);
1692 return -EAGAIN;
1693 }
1694
1695 reada_for_balance(p, level);
1696 ret = balance_level(trans, root, p, level);
1697 if (ret)
1698 return ret;
1699
1700 b = p->nodes[level];
1701 if (!b) {
1702 btrfs_release_path(p);
1703 return -EAGAIN;
1704 }
1705 BUG_ON(btrfs_header_nritems(b) == 1);
1706 }
1707 return ret;
1708}
1709
1710int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
1711 u64 iobjectid, u64 ioff, u8 key_type,
1712 struct btrfs_key *found_key)
1713{
1714 int ret;
1715 struct btrfs_key key;
1716 struct extent_buffer *eb;
1717
1718 ASSERT(path);
1719 ASSERT(found_key);
1720
1721 key.type = key_type;
1722 key.objectid = iobjectid;
1723 key.offset = ioff;
1724
1725 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1726 if (ret < 0)
1727 return ret;
1728
1729 eb = path->nodes[0];
1730 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1731 ret = btrfs_next_leaf(fs_root, path);
1732 if (ret)
1733 return ret;
1734 eb = path->nodes[0];
1735 }
1736
1737 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1738 if (found_key->type != key.type ||
1739 found_key->objectid != key.objectid)
1740 return 1;
1741
1742 return 0;
1743}
1744
1745static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
1746 struct btrfs_path *p,
1747 int write_lock_level)
1748{
1749 struct extent_buffer *b;
1750 int root_lock = 0;
1751 int level = 0;
1752
1753 if (p->search_commit_root) {
1754 b = root->commit_root;
1755 atomic_inc(&b->refs);
1756 level = btrfs_header_level(b);
1757 /*
1758 * Ensure that all callers have set skip_locking when
1759 * p->search_commit_root = 1.
1760 */
1761 ASSERT(p->skip_locking == 1);
1762
1763 goto out;
1764 }
1765
1766 if (p->skip_locking) {
1767 b = btrfs_root_node(root);
1768 level = btrfs_header_level(b);
1769 goto out;
1770 }
1771
1772 /* We try very hard to do read locks on the root */
1773 root_lock = BTRFS_READ_LOCK;
1774
1775 /*
1776 * If the level is set to maximum, we can skip trying to get the read
1777 * lock.
1778 */
1779 if (write_lock_level < BTRFS_MAX_LEVEL) {
1780 /*
1781 * We don't know the level of the root node until we actually
1782 * have it read locked
1783 */
1784 if (p->nowait) {
1785 b = btrfs_try_read_lock_root_node(root);
1786 if (IS_ERR(b))
1787 return b;
1788 } else {
1789 b = btrfs_read_lock_root_node(root);
1790 }
1791 level = btrfs_header_level(b);
1792 if (level > write_lock_level)
1793 goto out;
1794
1795 /* Whoops, must trade for write lock */
1796 btrfs_tree_read_unlock(b);
1797 free_extent_buffer(b);
1798 }
1799
1800 b = btrfs_lock_root_node(root);
1801 root_lock = BTRFS_WRITE_LOCK;
1802
1803 /* The level might have changed, check again */
1804 level = btrfs_header_level(b);
1805
1806out:
1807 /*
1808 * The root may have failed to write out at some point, and thus is no
1809 * longer valid, return an error in this case.
1810 */
1811 if (!extent_buffer_uptodate(b)) {
1812 if (root_lock)
1813 btrfs_tree_unlock_rw(b, root_lock);
1814 free_extent_buffer(b);
1815 return ERR_PTR(-EIO);
1816 }
1817
1818 p->nodes[level] = b;
1819 if (!p->skip_locking)
1820 p->locks[level] = root_lock;
1821 /*
1822 * Callers are responsible for dropping b's references.
1823 */
1824 return b;
1825}
1826
1827/*
1828 * Replace the extent buffer at the lowest level of the path with a cloned
1829 * version. The purpose is to be able to use it safely, after releasing the
1830 * commit root semaphore, even if relocation is happening in parallel, the
1831 * transaction used for relocation is committed and the extent buffer is
1832 * reallocated in the next transaction.
1833 *
1834 * This is used in a context where the caller does not prevent transaction
1835 * commits from happening, either by holding a transaction handle or holding
1836 * some lock, while it's doing searches through a commit root.
1837 * At the moment it's only used for send operations.
1838 */
1839static int finish_need_commit_sem_search(struct btrfs_path *path)
1840{
1841 const int i = path->lowest_level;
1842 const int slot = path->slots[i];
1843 struct extent_buffer *lowest = path->nodes[i];
1844 struct extent_buffer *clone;
1845
1846 ASSERT(path->need_commit_sem);
1847
1848 if (!lowest)
1849 return 0;
1850
1851 lockdep_assert_held_read(&lowest->fs_info->commit_root_sem);
1852
1853 clone = btrfs_clone_extent_buffer(lowest);
1854 if (!clone)
1855 return -ENOMEM;
1856
1857 btrfs_release_path(path);
1858 path->nodes[i] = clone;
1859 path->slots[i] = slot;
1860
1861 return 0;
1862}
1863
1864static inline int search_for_key_slot(struct extent_buffer *eb,
1865 int search_low_slot,
1866 const struct btrfs_key *key,
1867 int prev_cmp,
1868 int *slot)
1869{
1870 /*
1871 * If a previous call to btrfs_bin_search() on a parent node returned an
1872 * exact match (prev_cmp == 0), we can safely assume the target key will
1873 * always be at slot 0 on lower levels, since each key pointer
1874 * (struct btrfs_key_ptr) refers to the lowest key accessible from the
1875 * subtree it points to. Thus we can skip searching lower levels.
1876 */
1877 if (prev_cmp == 0) {
1878 *slot = 0;
1879 return 0;
1880 }
1881
1882 return btrfs_bin_search(eb, search_low_slot, key, slot);
1883}
1884
1885static int search_leaf(struct btrfs_trans_handle *trans,
1886 struct btrfs_root *root,
1887 const struct btrfs_key *key,
1888 struct btrfs_path *path,
1889 int ins_len,
1890 int prev_cmp)
1891{
1892 struct extent_buffer *leaf = path->nodes[0];
1893 int leaf_free_space = -1;
1894 int search_low_slot = 0;
1895 int ret;
1896 bool do_bin_search = true;
1897
1898 /*
1899 * If we are doing an insertion, the leaf has enough free space and the
1900 * destination slot for the key is not slot 0, then we can unlock our
1901 * write lock on the parent, and any other upper nodes, before doing the
1902 * binary search on the leaf (with search_for_key_slot()), allowing other
1903 * tasks to lock the parent and any other upper nodes.
1904 */
1905 if (ins_len > 0) {
1906 /*
1907 * Cache the leaf free space, since we will need it later and it
1908 * will not change until then.
1909 */
1910 leaf_free_space = btrfs_leaf_free_space(leaf);
1911
1912 /*
1913 * !path->locks[1] means we have a single node tree, the leaf is
1914 * the root of the tree.
1915 */
1916 if (path->locks[1] && leaf_free_space >= ins_len) {
1917 struct btrfs_disk_key first_key;
1918
1919 ASSERT(btrfs_header_nritems(leaf) > 0);
1920 btrfs_item_key(leaf, &first_key, 0);
1921
1922 /*
1923 * Doing the extra comparison with the first key is cheap,
1924 * taking into account that the first key is very likely
1925 * already in a cache line because it immediately follows
1926 * the extent buffer's header and we have recently accessed
1927 * the header's level field.
1928 */
1929 ret = btrfs_comp_keys(&first_key, key);
1930 if (ret < 0) {
1931 /*
1932 * The first key is smaller than the key we want
1933 * to insert, so we are safe to unlock all upper
1934 * nodes and we have to do the binary search.
1935 *
1936 * We do use btrfs_unlock_up_safe() and not
1937 * unlock_up() because the later does not unlock
1938 * nodes with a slot of 0 - we can safely unlock
1939 * any node even if its slot is 0 since in this
1940 * case the key does not end up at slot 0 of the
1941 * leaf and there's no need to split the leaf.
1942 */
1943 btrfs_unlock_up_safe(path, 1);
1944 search_low_slot = 1;
1945 } else {
1946 /*
1947 * The first key is >= then the key we want to
1948 * insert, so we can skip the binary search as
1949 * the target key will be at slot 0.
1950 *
1951 * We can not unlock upper nodes when the key is
1952 * less than the first key, because we will need
1953 * to update the key at slot 0 of the parent node
1954 * and possibly of other upper nodes too.
1955 * If the key matches the first key, then we can
1956 * unlock all the upper nodes, using
1957 * btrfs_unlock_up_safe() instead of unlock_up()
1958 * as stated above.
1959 */
1960 if (ret == 0)
1961 btrfs_unlock_up_safe(path, 1);
1962 /*
1963 * ret is already 0 or 1, matching the result of
1964 * a btrfs_bin_search() call, so there is no need
1965 * to adjust it.
1966 */
1967 do_bin_search = false;
1968 path->slots[0] = 0;
1969 }
1970 }
1971 }
1972
1973 if (do_bin_search) {
1974 ret = search_for_key_slot(leaf, search_low_slot, key,
1975 prev_cmp, &path->slots[0]);
1976 if (ret < 0)
1977 return ret;
1978 }
1979
1980 if (ins_len > 0) {
1981 /*
1982 * Item key already exists. In this case, if we are allowed to
1983 * insert the item (for example, in dir_item case, item key
1984 * collision is allowed), it will be merged with the original
1985 * item. Only the item size grows, no new btrfs item will be
1986 * added. If search_for_extension is not set, ins_len already
1987 * accounts the size btrfs_item, deduct it here so leaf space
1988 * check will be correct.
1989 */
1990 if (ret == 0 && !path->search_for_extension) {
1991 ASSERT(ins_len >= sizeof(struct btrfs_item));
1992 ins_len -= sizeof(struct btrfs_item);
1993 }
1994
1995 ASSERT(leaf_free_space >= 0);
1996
1997 if (leaf_free_space < ins_len) {
1998 int err;
1999
2000 err = split_leaf(trans, root, key, path, ins_len,
2001 (ret == 0));
2002 ASSERT(err <= 0);
2003 if (WARN_ON(err > 0))
2004 err = -EUCLEAN;
2005 if (err)
2006 ret = err;
2007 }
2008 }
2009
2010 return ret;
2011}
2012
2013/*
2014 * Look for a key in a tree and perform necessary modifications to preserve
2015 * tree invariants.
2016 *
2017 * @trans: Handle of transaction, used when modifying the tree
2018 * @p: Holds all btree nodes along the search path
2019 * @root: The root node of the tree
2020 * @key: The key we are looking for
2021 * @ins_len: Indicates purpose of search:
2022 * >0 for inserts it's size of item inserted (*)
2023 * <0 for deletions
2024 * 0 for plain searches, not modifying the tree
2025 *
2026 * (*) If size of item inserted doesn't include
2027 * sizeof(struct btrfs_item), then p->search_for_extension must
2028 * be set.
2029 * @cow: boolean should CoW operations be performed. Must always be 1
2030 * when modifying the tree.
2031 *
2032 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
2033 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
2034 *
2035 * If @key is found, 0 is returned and you can find the item in the leaf level
2036 * of the path (level 0)
2037 *
2038 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
2039 * points to the slot where it should be inserted
2040 *
2041 * If an error is encountered while searching the tree a negative error number
2042 * is returned
2043 */
2044int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2045 const struct btrfs_key *key, struct btrfs_path *p,
2046 int ins_len, int cow)
2047{
2048 struct btrfs_fs_info *fs_info;
2049 struct extent_buffer *b;
2050 int slot;
2051 int ret;
2052 int err;
2053 int level;
2054 int lowest_unlock = 1;
2055 /* everything at write_lock_level or lower must be write locked */
2056 int write_lock_level = 0;
2057 u8 lowest_level = 0;
2058 int min_write_lock_level;
2059 int prev_cmp;
2060
2061 if (!root)
2062 return -EINVAL;
2063
2064 fs_info = root->fs_info;
2065 might_sleep();
2066
2067 lowest_level = p->lowest_level;
2068 WARN_ON(lowest_level && ins_len > 0);
2069 WARN_ON(p->nodes[0] != NULL);
2070 BUG_ON(!cow && ins_len);
2071
2072 /*
2073 * For now only allow nowait for read only operations. There's no
2074 * strict reason why we can't, we just only need it for reads so it's
2075 * only implemented for reads.
2076 */
2077 ASSERT(!p->nowait || !cow);
2078
2079 if (ins_len < 0) {
2080 lowest_unlock = 2;
2081
2082 /* when we are removing items, we might have to go up to level
2083 * two as we update tree pointers Make sure we keep write
2084 * for those levels as well
2085 */
2086 write_lock_level = 2;
2087 } else if (ins_len > 0) {
2088 /*
2089 * for inserting items, make sure we have a write lock on
2090 * level 1 so we can update keys
2091 */
2092 write_lock_level = 1;
2093 }
2094
2095 if (!cow)
2096 write_lock_level = -1;
2097
2098 if (cow && (p->keep_locks || p->lowest_level))
2099 write_lock_level = BTRFS_MAX_LEVEL;
2100
2101 min_write_lock_level = write_lock_level;
2102
2103 if (p->need_commit_sem) {
2104 ASSERT(p->search_commit_root);
2105 if (p->nowait) {
2106 if (!down_read_trylock(&fs_info->commit_root_sem))
2107 return -EAGAIN;
2108 } else {
2109 down_read(&fs_info->commit_root_sem);
2110 }
2111 }
2112
2113again:
2114 prev_cmp = -1;
2115 b = btrfs_search_slot_get_root(root, p, write_lock_level);
2116 if (IS_ERR(b)) {
2117 ret = PTR_ERR(b);
2118 goto done;
2119 }
2120
2121 while (b) {
2122 int dec = 0;
2123
2124 level = btrfs_header_level(b);
2125
2126 if (cow) {
2127 bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2128
2129 /*
2130 * if we don't really need to cow this block
2131 * then we don't want to set the path blocking,
2132 * so we test it here
2133 */
2134 if (!should_cow_block(trans, root, b))
2135 goto cow_done;
2136
2137 /*
2138 * must have write locks on this node and the
2139 * parent
2140 */
2141 if (level > write_lock_level ||
2142 (level + 1 > write_lock_level &&
2143 level + 1 < BTRFS_MAX_LEVEL &&
2144 p->nodes[level + 1])) {
2145 write_lock_level = level + 1;
2146 btrfs_release_path(p);
2147 goto again;
2148 }
2149
2150 if (last_level)
2151 err = btrfs_cow_block(trans, root, b, NULL, 0,
2152 &b,
2153 BTRFS_NESTING_COW);
2154 else
2155 err = btrfs_cow_block(trans, root, b,
2156 p->nodes[level + 1],
2157 p->slots[level + 1], &b,
2158 BTRFS_NESTING_COW);
2159 if (err) {
2160 ret = err;
2161 goto done;
2162 }
2163 }
2164cow_done:
2165 p->nodes[level] = b;
2166
2167 /*
2168 * we have a lock on b and as long as we aren't changing
2169 * the tree, there is no way to for the items in b to change.
2170 * It is safe to drop the lock on our parent before we
2171 * go through the expensive btree search on b.
2172 *
2173 * If we're inserting or deleting (ins_len != 0), then we might
2174 * be changing slot zero, which may require changing the parent.
2175 * So, we can't drop the lock until after we know which slot
2176 * we're operating on.
2177 */
2178 if (!ins_len && !p->keep_locks) {
2179 int u = level + 1;
2180
2181 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2182 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2183 p->locks[u] = 0;
2184 }
2185 }
2186
2187 if (level == 0) {
2188 if (ins_len > 0)
2189 ASSERT(write_lock_level >= 1);
2190
2191 ret = search_leaf(trans, root, key, p, ins_len, prev_cmp);
2192 if (!p->search_for_split)
2193 unlock_up(p, level, lowest_unlock,
2194 min_write_lock_level, NULL);
2195 goto done;
2196 }
2197
2198 ret = search_for_key_slot(b, 0, key, prev_cmp, &slot);
2199 if (ret < 0)
2200 goto done;
2201 prev_cmp = ret;
2202
2203 if (ret && slot > 0) {
2204 dec = 1;
2205 slot--;
2206 }
2207 p->slots[level] = slot;
2208 err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
2209 &write_lock_level);
2210 if (err == -EAGAIN)
2211 goto again;
2212 if (err) {
2213 ret = err;
2214 goto done;
2215 }
2216 b = p->nodes[level];
2217 slot = p->slots[level];
2218
2219 /*
2220 * Slot 0 is special, if we change the key we have to update
2221 * the parent pointer which means we must have a write lock on
2222 * the parent
2223 */
2224 if (slot == 0 && ins_len && write_lock_level < level + 1) {
2225 write_lock_level = level + 1;
2226 btrfs_release_path(p);
2227 goto again;
2228 }
2229
2230 unlock_up(p, level, lowest_unlock, min_write_lock_level,
2231 &write_lock_level);
2232
2233 if (level == lowest_level) {
2234 if (dec)
2235 p->slots[level]++;
2236 goto done;
2237 }
2238
2239 err = read_block_for_search(root, p, &b, slot, key);
2240 if (err == -EAGAIN && !p->nowait)
2241 goto again;
2242 if (err) {
2243 ret = err;
2244 goto done;
2245 }
2246
2247 if (!p->skip_locking) {
2248 level = btrfs_header_level(b);
2249
2250 btrfs_maybe_reset_lockdep_class(root, b);
2251
2252 if (level <= write_lock_level) {
2253 btrfs_tree_lock(b);
2254 p->locks[level] = BTRFS_WRITE_LOCK;
2255 } else {
2256 if (p->nowait) {
2257 if (!btrfs_try_tree_read_lock(b)) {
2258 free_extent_buffer(b);
2259 ret = -EAGAIN;
2260 goto done;
2261 }
2262 } else {
2263 btrfs_tree_read_lock(b);
2264 }
2265 p->locks[level] = BTRFS_READ_LOCK;
2266 }
2267 p->nodes[level] = b;
2268 }
2269 }
2270 ret = 1;
2271done:
2272 if (ret < 0 && !p->skip_release_on_error)
2273 btrfs_release_path(p);
2274
2275 if (p->need_commit_sem) {
2276 int ret2;
2277
2278 ret2 = finish_need_commit_sem_search(p);
2279 up_read(&fs_info->commit_root_sem);
2280 if (ret2)
2281 ret = ret2;
2282 }
2283
2284 return ret;
2285}
2286ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO);
2287
2288/*
2289 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2290 * current state of the tree together with the operations recorded in the tree
2291 * modification log to search for the key in a previous version of this tree, as
2292 * denoted by the time_seq parameter.
2293 *
2294 * Naturally, there is no support for insert, delete or cow operations.
2295 *
2296 * The resulting path and return value will be set up as if we called
2297 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2298 */
2299int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2300 struct btrfs_path *p, u64 time_seq)
2301{
2302 struct btrfs_fs_info *fs_info = root->fs_info;
2303 struct extent_buffer *b;
2304 int slot;
2305 int ret;
2306 int err;
2307 int level;
2308 int lowest_unlock = 1;
2309 u8 lowest_level = 0;
2310
2311 lowest_level = p->lowest_level;
2312 WARN_ON(p->nodes[0] != NULL);
2313 ASSERT(!p->nowait);
2314
2315 if (p->search_commit_root) {
2316 BUG_ON(time_seq);
2317 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2318 }
2319
2320again:
2321 b = btrfs_get_old_root(root, time_seq);
2322 if (!b) {
2323 ret = -EIO;
2324 goto done;
2325 }
2326 level = btrfs_header_level(b);
2327 p->locks[level] = BTRFS_READ_LOCK;
2328
2329 while (b) {
2330 int dec = 0;
2331
2332 level = btrfs_header_level(b);
2333 p->nodes[level] = b;
2334
2335 /*
2336 * we have a lock on b and as long as we aren't changing
2337 * the tree, there is no way to for the items in b to change.
2338 * It is safe to drop the lock on our parent before we
2339 * go through the expensive btree search on b.
2340 */
2341 btrfs_unlock_up_safe(p, level + 1);
2342
2343 ret = btrfs_bin_search(b, 0, key, &slot);
2344 if (ret < 0)
2345 goto done;
2346
2347 if (level == 0) {
2348 p->slots[level] = slot;
2349 unlock_up(p, level, lowest_unlock, 0, NULL);
2350 goto done;
2351 }
2352
2353 if (ret && slot > 0) {
2354 dec = 1;
2355 slot--;
2356 }
2357 p->slots[level] = slot;
2358 unlock_up(p, level, lowest_unlock, 0, NULL);
2359
2360 if (level == lowest_level) {
2361 if (dec)
2362 p->slots[level]++;
2363 goto done;
2364 }
2365
2366 err = read_block_for_search(root, p, &b, slot, key);
2367 if (err == -EAGAIN && !p->nowait)
2368 goto again;
2369 if (err) {
2370 ret = err;
2371 goto done;
2372 }
2373
2374 level = btrfs_header_level(b);
2375 btrfs_tree_read_lock(b);
2376 b = btrfs_tree_mod_log_rewind(fs_info, b, time_seq);
2377 if (!b) {
2378 ret = -ENOMEM;
2379 goto done;
2380 }
2381 p->locks[level] = BTRFS_READ_LOCK;
2382 p->nodes[level] = b;
2383 }
2384 ret = 1;
2385done:
2386 if (ret < 0)
2387 btrfs_release_path(p);
2388
2389 return ret;
2390}
2391
2392/*
2393 * Search the tree again to find a leaf with smaller keys.
2394 * Returns 0 if it found something.
2395 * Returns 1 if there are no smaller keys.
2396 * Returns < 0 on error.
2397 *
2398 * This may release the path, and so you may lose any locks held at the
2399 * time you call it.
2400 */
2401static int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
2402{
2403 struct btrfs_key key;
2404 struct btrfs_key orig_key;
2405 struct btrfs_disk_key found_key;
2406 int ret;
2407
2408 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
2409 orig_key = key;
2410
2411 if (key.offset > 0) {
2412 key.offset--;
2413 } else if (key.type > 0) {
2414 key.type--;
2415 key.offset = (u64)-1;
2416 } else if (key.objectid > 0) {
2417 key.objectid--;
2418 key.type = (u8)-1;
2419 key.offset = (u64)-1;
2420 } else {
2421 return 1;
2422 }
2423
2424 btrfs_release_path(path);
2425 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2426 if (ret <= 0)
2427 return ret;
2428
2429 /*
2430 * Previous key not found. Even if we were at slot 0 of the leaf we had
2431 * before releasing the path and calling btrfs_search_slot(), we now may
2432 * be in a slot pointing to the same original key - this can happen if
2433 * after we released the path, one of more items were moved from a
2434 * sibling leaf into the front of the leaf we had due to an insertion
2435 * (see push_leaf_right()).
2436 * If we hit this case and our slot is > 0 and just decrement the slot
2437 * so that the caller does not process the same key again, which may or
2438 * may not break the caller, depending on its logic.
2439 */
2440 if (path->slots[0] < btrfs_header_nritems(path->nodes[0])) {
2441 btrfs_item_key(path->nodes[0], &found_key, path->slots[0]);
2442 ret = btrfs_comp_keys(&found_key, &orig_key);
2443 if (ret == 0) {
2444 if (path->slots[0] > 0) {
2445 path->slots[0]--;
2446 return 0;
2447 }
2448 /*
2449 * At slot 0, same key as before, it means orig_key is
2450 * the lowest, leftmost, key in the tree. We're done.
2451 */
2452 return 1;
2453 }
2454 }
2455
2456 btrfs_item_key(path->nodes[0], &found_key, 0);
2457 ret = btrfs_comp_keys(&found_key, &key);
2458 /*
2459 * We might have had an item with the previous key in the tree right
2460 * before we released our path. And after we released our path, that
2461 * item might have been pushed to the first slot (0) of the leaf we
2462 * were holding due to a tree balance. Alternatively, an item with the
2463 * previous key can exist as the only element of a leaf (big fat item).
2464 * Therefore account for these 2 cases, so that our callers (like
2465 * btrfs_previous_item) don't miss an existing item with a key matching
2466 * the previous key we computed above.
2467 */
2468 if (ret <= 0)
2469 return 0;
2470 return 1;
2471}
2472
2473/*
2474 * helper to use instead of search slot if no exact match is needed but
2475 * instead the next or previous item should be returned.
2476 * When find_higher is true, the next higher item is returned, the next lower
2477 * otherwise.
2478 * When return_any and find_higher are both true, and no higher item is found,
2479 * return the next lower instead.
2480 * When return_any is true and find_higher is false, and no lower item is found,
2481 * return the next higher instead.
2482 * It returns 0 if any item is found, 1 if none is found (tree empty), and
2483 * < 0 on error
2484 */
2485int btrfs_search_slot_for_read(struct btrfs_root *root,
2486 const struct btrfs_key *key,
2487 struct btrfs_path *p, int find_higher,
2488 int return_any)
2489{
2490 int ret;
2491 struct extent_buffer *leaf;
2492
2493again:
2494 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
2495 if (ret <= 0)
2496 return ret;
2497 /*
2498 * a return value of 1 means the path is at the position where the
2499 * item should be inserted. Normally this is the next bigger item,
2500 * but in case the previous item is the last in a leaf, path points
2501 * to the first free slot in the previous leaf, i.e. at an invalid
2502 * item.
2503 */
2504 leaf = p->nodes[0];
2505
2506 if (find_higher) {
2507 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
2508 ret = btrfs_next_leaf(root, p);
2509 if (ret <= 0)
2510 return ret;
2511 if (!return_any)
2512 return 1;
2513 /*
2514 * no higher item found, return the next
2515 * lower instead
2516 */
2517 return_any = 0;
2518 find_higher = 0;
2519 btrfs_release_path(p);
2520 goto again;
2521 }
2522 } else {
2523 if (p->slots[0] == 0) {
2524 ret = btrfs_prev_leaf(root, p);
2525 if (ret < 0)
2526 return ret;
2527 if (!ret) {
2528 leaf = p->nodes[0];
2529 if (p->slots[0] == btrfs_header_nritems(leaf))
2530 p->slots[0]--;
2531 return 0;
2532 }
2533 if (!return_any)
2534 return 1;
2535 /*
2536 * no lower item found, return the next
2537 * higher instead
2538 */
2539 return_any = 0;
2540 find_higher = 1;
2541 btrfs_release_path(p);
2542 goto again;
2543 } else {
2544 --p->slots[0];
2545 }
2546 }
2547 return 0;
2548}
2549
2550/*
2551 * Execute search and call btrfs_previous_item to traverse backwards if the item
2552 * was not found.
2553 *
2554 * Return 0 if found, 1 if not found and < 0 if error.
2555 */
2556int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key,
2557 struct btrfs_path *path)
2558{
2559 int ret;
2560
2561 ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
2562 if (ret > 0)
2563 ret = btrfs_previous_item(root, path, key->objectid, key->type);
2564
2565 if (ret == 0)
2566 btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
2567
2568 return ret;
2569}
2570
2571/*
2572 * Search for a valid slot for the given path.
2573 *
2574 * @root: The root node of the tree.
2575 * @key: Will contain a valid item if found.
2576 * @path: The starting point to validate the slot.
2577 *
2578 * Return: 0 if the item is valid
2579 * 1 if not found
2580 * <0 if error.
2581 */
2582int btrfs_get_next_valid_item(struct btrfs_root *root, struct btrfs_key *key,
2583 struct btrfs_path *path)
2584{
2585 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
2586 int ret;
2587
2588 ret = btrfs_next_leaf(root, path);
2589 if (ret)
2590 return ret;
2591 }
2592
2593 btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
2594 return 0;
2595}
2596
2597/*
2598 * adjust the pointers going up the tree, starting at level
2599 * making sure the right key of each node is points to 'key'.
2600 * This is used after shifting pointers to the left, so it stops
2601 * fixing up pointers when a given leaf/node is not in slot 0 of the
2602 * higher levels
2603 *
2604 */
2605static void fixup_low_keys(struct btrfs_trans_handle *trans,
2606 const struct btrfs_path *path,
2607 const struct btrfs_disk_key *key, int level)
2608{
2609 int i;
2610 struct extent_buffer *t;
2611 int ret;
2612
2613 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2614 int tslot = path->slots[i];
2615
2616 if (!path->nodes[i])
2617 break;
2618 t = path->nodes[i];
2619 ret = btrfs_tree_mod_log_insert_key(t, tslot,
2620 BTRFS_MOD_LOG_KEY_REPLACE);
2621 BUG_ON(ret < 0);
2622 btrfs_set_node_key(t, key, tslot);
2623 btrfs_mark_buffer_dirty(trans, path->nodes[i]);
2624 if (tslot != 0)
2625 break;
2626 }
2627}
2628
2629/*
2630 * update item key.
2631 *
2632 * This function isn't completely safe. It's the caller's responsibility
2633 * that the new key won't break the order
2634 */
2635void btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
2636 const struct btrfs_path *path,
2637 const struct btrfs_key *new_key)
2638{
2639 struct btrfs_fs_info *fs_info = trans->fs_info;
2640 struct btrfs_disk_key disk_key;
2641 struct extent_buffer *eb;
2642 int slot;
2643
2644 eb = path->nodes[0];
2645 slot = path->slots[0];
2646 if (slot > 0) {
2647 btrfs_item_key(eb, &disk_key, slot - 1);
2648 if (unlikely(btrfs_comp_keys(&disk_key, new_key) >= 0)) {
2649 btrfs_print_leaf(eb);
2650 btrfs_crit(fs_info,
2651 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2652 slot, btrfs_disk_key_objectid(&disk_key),
2653 btrfs_disk_key_type(&disk_key),
2654 btrfs_disk_key_offset(&disk_key),
2655 new_key->objectid, new_key->type,
2656 new_key->offset);
2657 BUG();
2658 }
2659 }
2660 if (slot < btrfs_header_nritems(eb) - 1) {
2661 btrfs_item_key(eb, &disk_key, slot + 1);
2662 if (unlikely(btrfs_comp_keys(&disk_key, new_key) <= 0)) {
2663 btrfs_print_leaf(eb);
2664 btrfs_crit(fs_info,
2665 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2666 slot, btrfs_disk_key_objectid(&disk_key),
2667 btrfs_disk_key_type(&disk_key),
2668 btrfs_disk_key_offset(&disk_key),
2669 new_key->objectid, new_key->type,
2670 new_key->offset);
2671 BUG();
2672 }
2673 }
2674
2675 btrfs_cpu_key_to_disk(&disk_key, new_key);
2676 btrfs_set_item_key(eb, &disk_key, slot);
2677 btrfs_mark_buffer_dirty(trans, eb);
2678 if (slot == 0)
2679 fixup_low_keys(trans, path, &disk_key, 1);
2680}
2681
2682/*
2683 * Check key order of two sibling extent buffers.
2684 *
2685 * Return true if something is wrong.
2686 * Return false if everything is fine.
2687 *
2688 * Tree-checker only works inside one tree block, thus the following
2689 * corruption can not be detected by tree-checker:
2690 *
2691 * Leaf @left | Leaf @right
2692 * --------------------------------------------------------------
2693 * | 1 | 2 | 3 | 4 | 5 | f6 | | 7 | 8 |
2694 *
2695 * Key f6 in leaf @left itself is valid, but not valid when the next
2696 * key in leaf @right is 7.
2697 * This can only be checked at tree block merge time.
2698 * And since tree checker has ensured all key order in each tree block
2699 * is correct, we only need to bother the last key of @left and the first
2700 * key of @right.
2701 */
2702static bool check_sibling_keys(const struct extent_buffer *left,
2703 const struct extent_buffer *right)
2704{
2705 struct btrfs_key left_last;
2706 struct btrfs_key right_first;
2707 int level = btrfs_header_level(left);
2708 int nr_left = btrfs_header_nritems(left);
2709 int nr_right = btrfs_header_nritems(right);
2710
2711 /* No key to check in one of the tree blocks */
2712 if (!nr_left || !nr_right)
2713 return false;
2714
2715 if (level) {
2716 btrfs_node_key_to_cpu(left, &left_last, nr_left - 1);
2717 btrfs_node_key_to_cpu(right, &right_first, 0);
2718 } else {
2719 btrfs_item_key_to_cpu(left, &left_last, nr_left - 1);
2720 btrfs_item_key_to_cpu(right, &right_first, 0);
2721 }
2722
2723 if (unlikely(btrfs_comp_cpu_keys(&left_last, &right_first) >= 0)) {
2724 btrfs_crit(left->fs_info, "left extent buffer:");
2725 btrfs_print_tree(left, false);
2726 btrfs_crit(left->fs_info, "right extent buffer:");
2727 btrfs_print_tree(right, false);
2728 btrfs_crit(left->fs_info,
2729"bad key order, sibling blocks, left last (%llu %u %llu) right first (%llu %u %llu)",
2730 left_last.objectid, left_last.type,
2731 left_last.offset, right_first.objectid,
2732 right_first.type, right_first.offset);
2733 return true;
2734 }
2735 return false;
2736}
2737
2738/*
2739 * try to push data from one node into the next node left in the
2740 * tree.
2741 *
2742 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2743 * error, and > 0 if there was no room in the left hand block.
2744 */
2745static int push_node_left(struct btrfs_trans_handle *trans,
2746 struct extent_buffer *dst,
2747 struct extent_buffer *src, int empty)
2748{
2749 struct btrfs_fs_info *fs_info = trans->fs_info;
2750 int push_items = 0;
2751 int src_nritems;
2752 int dst_nritems;
2753 int ret = 0;
2754
2755 src_nritems = btrfs_header_nritems(src);
2756 dst_nritems = btrfs_header_nritems(dst);
2757 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2758 WARN_ON(btrfs_header_generation(src) != trans->transid);
2759 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2760
2761 if (!empty && src_nritems <= 8)
2762 return 1;
2763
2764 if (push_items <= 0)
2765 return 1;
2766
2767 if (empty) {
2768 push_items = min(src_nritems, push_items);
2769 if (push_items < src_nritems) {
2770 /* leave at least 8 pointers in the node if
2771 * we aren't going to empty it
2772 */
2773 if (src_nritems - push_items < 8) {
2774 if (push_items <= 8)
2775 return 1;
2776 push_items -= 8;
2777 }
2778 }
2779 } else
2780 push_items = min(src_nritems - 8, push_items);
2781
2782 /* dst is the left eb, src is the middle eb */
2783 if (check_sibling_keys(dst, src)) {
2784 ret = -EUCLEAN;
2785 btrfs_abort_transaction(trans, ret);
2786 return ret;
2787 }
2788 ret = btrfs_tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
2789 if (ret) {
2790 btrfs_abort_transaction(trans, ret);
2791 return ret;
2792 }
2793 copy_extent_buffer(dst, src,
2794 btrfs_node_key_ptr_offset(dst, dst_nritems),
2795 btrfs_node_key_ptr_offset(src, 0),
2796 push_items * sizeof(struct btrfs_key_ptr));
2797
2798 if (push_items < src_nritems) {
2799 /*
2800 * btrfs_tree_mod_log_eb_copy handles logging the move, so we
2801 * don't need to do an explicit tree mod log operation for it.
2802 */
2803 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(src, 0),
2804 btrfs_node_key_ptr_offset(src, push_items),
2805 (src_nritems - push_items) *
2806 sizeof(struct btrfs_key_ptr));
2807 }
2808 btrfs_set_header_nritems(src, src_nritems - push_items);
2809 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2810 btrfs_mark_buffer_dirty(trans, src);
2811 btrfs_mark_buffer_dirty(trans, dst);
2812
2813 return ret;
2814}
2815
2816/*
2817 * try to push data from one node into the next node right in the
2818 * tree.
2819 *
2820 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
2821 * error, and > 0 if there was no room in the right hand block.
2822 *
2823 * this will only push up to 1/2 the contents of the left node over
2824 */
2825static int balance_node_right(struct btrfs_trans_handle *trans,
2826 struct extent_buffer *dst,
2827 struct extent_buffer *src)
2828{
2829 struct btrfs_fs_info *fs_info = trans->fs_info;
2830 int push_items = 0;
2831 int max_push;
2832 int src_nritems;
2833 int dst_nritems;
2834 int ret = 0;
2835
2836 WARN_ON(btrfs_header_generation(src) != trans->transid);
2837 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2838
2839 src_nritems = btrfs_header_nritems(src);
2840 dst_nritems = btrfs_header_nritems(dst);
2841 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2842 if (push_items <= 0)
2843 return 1;
2844
2845 if (src_nritems < 4)
2846 return 1;
2847
2848 max_push = src_nritems / 2 + 1;
2849 /* don't try to empty the node */
2850 if (max_push >= src_nritems)
2851 return 1;
2852
2853 if (max_push < push_items)
2854 push_items = max_push;
2855
2856 /* dst is the right eb, src is the middle eb */
2857 if (check_sibling_keys(src, dst)) {
2858 ret = -EUCLEAN;
2859 btrfs_abort_transaction(trans, ret);
2860 return ret;
2861 }
2862
2863 /*
2864 * btrfs_tree_mod_log_eb_copy handles logging the move, so we don't
2865 * need to do an explicit tree mod log operation for it.
2866 */
2867 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(dst, push_items),
2868 btrfs_node_key_ptr_offset(dst, 0),
2869 (dst_nritems) *
2870 sizeof(struct btrfs_key_ptr));
2871
2872 ret = btrfs_tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
2873 push_items);
2874 if (ret) {
2875 btrfs_abort_transaction(trans, ret);
2876 return ret;
2877 }
2878 copy_extent_buffer(dst, src,
2879 btrfs_node_key_ptr_offset(dst, 0),
2880 btrfs_node_key_ptr_offset(src, src_nritems - push_items),
2881 push_items * sizeof(struct btrfs_key_ptr));
2882
2883 btrfs_set_header_nritems(src, src_nritems - push_items);
2884 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2885
2886 btrfs_mark_buffer_dirty(trans, src);
2887 btrfs_mark_buffer_dirty(trans, dst);
2888
2889 return ret;
2890}
2891
2892/*
2893 * helper function to insert a new root level in the tree.
2894 * A new node is allocated, and a single item is inserted to
2895 * point to the existing root
2896 *
2897 * returns zero on success or < 0 on failure.
2898 */
2899static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2900 struct btrfs_root *root,
2901 struct btrfs_path *path, int level)
2902{
2903 u64 lower_gen;
2904 struct extent_buffer *lower;
2905 struct extent_buffer *c;
2906 struct extent_buffer *old;
2907 struct btrfs_disk_key lower_key;
2908 int ret;
2909
2910 BUG_ON(path->nodes[level]);
2911 BUG_ON(path->nodes[level-1] != root->node);
2912
2913 lower = path->nodes[level-1];
2914 if (level == 1)
2915 btrfs_item_key(lower, &lower_key, 0);
2916 else
2917 btrfs_node_key(lower, &lower_key, 0);
2918
2919 c = btrfs_alloc_tree_block(trans, root, 0, btrfs_root_id(root),
2920 &lower_key, level, root->node->start, 0,
2921 0, BTRFS_NESTING_NEW_ROOT);
2922 if (IS_ERR(c))
2923 return PTR_ERR(c);
2924
2925 root_add_used_bytes(root);
2926
2927 btrfs_set_header_nritems(c, 1);
2928 btrfs_set_node_key(c, &lower_key, 0);
2929 btrfs_set_node_blockptr(c, 0, lower->start);
2930 lower_gen = btrfs_header_generation(lower);
2931 WARN_ON(lower_gen != trans->transid);
2932
2933 btrfs_set_node_ptr_generation(c, 0, lower_gen);
2934
2935 btrfs_mark_buffer_dirty(trans, c);
2936
2937 old = root->node;
2938 ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
2939 if (ret < 0) {
2940 int ret2;
2941
2942 ret2 = btrfs_free_tree_block(trans, btrfs_root_id(root), c, 0, 1);
2943 if (ret2 < 0)
2944 btrfs_abort_transaction(trans, ret2);
2945 btrfs_tree_unlock(c);
2946 free_extent_buffer(c);
2947 return ret;
2948 }
2949 rcu_assign_pointer(root->node, c);
2950
2951 /* the super has an extra ref to root->node */
2952 free_extent_buffer(old);
2953
2954 add_root_to_dirty_list(root);
2955 atomic_inc(&c->refs);
2956 path->nodes[level] = c;
2957 path->locks[level] = BTRFS_WRITE_LOCK;
2958 path->slots[level] = 0;
2959 return 0;
2960}
2961
2962/*
2963 * worker function to insert a single pointer in a node.
2964 * the node should have enough room for the pointer already
2965 *
2966 * slot and level indicate where you want the key to go, and
2967 * blocknr is the block the key points to.
2968 */
2969static int insert_ptr(struct btrfs_trans_handle *trans,
2970 const struct btrfs_path *path,
2971 const struct btrfs_disk_key *key, u64 bytenr,
2972 int slot, int level)
2973{
2974 struct extent_buffer *lower;
2975 int nritems;
2976 int ret;
2977
2978 BUG_ON(!path->nodes[level]);
2979 btrfs_assert_tree_write_locked(path->nodes[level]);
2980 lower = path->nodes[level];
2981 nritems = btrfs_header_nritems(lower);
2982 BUG_ON(slot > nritems);
2983 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
2984 if (slot != nritems) {
2985 if (level) {
2986 ret = btrfs_tree_mod_log_insert_move(lower, slot + 1,
2987 slot, nritems - slot);
2988 if (ret < 0) {
2989 btrfs_abort_transaction(trans, ret);
2990 return ret;
2991 }
2992 }
2993 memmove_extent_buffer(lower,
2994 btrfs_node_key_ptr_offset(lower, slot + 1),
2995 btrfs_node_key_ptr_offset(lower, slot),
2996 (nritems - slot) * sizeof(struct btrfs_key_ptr));
2997 }
2998 if (level) {
2999 ret = btrfs_tree_mod_log_insert_key(lower, slot,
3000 BTRFS_MOD_LOG_KEY_ADD);
3001 if (ret < 0) {
3002 btrfs_abort_transaction(trans, ret);
3003 return ret;
3004 }
3005 }
3006 btrfs_set_node_key(lower, key, slot);
3007 btrfs_set_node_blockptr(lower, slot, bytenr);
3008 WARN_ON(trans->transid == 0);
3009 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3010 btrfs_set_header_nritems(lower, nritems + 1);
3011 btrfs_mark_buffer_dirty(trans, lower);
3012
3013 return 0;
3014}
3015
3016/*
3017 * split the node at the specified level in path in two.
3018 * The path is corrected to point to the appropriate node after the split
3019 *
3020 * Before splitting this tries to make some room in the node by pushing
3021 * left and right, if either one works, it returns right away.
3022 *
3023 * returns 0 on success and < 0 on failure
3024 */
3025static noinline int split_node(struct btrfs_trans_handle *trans,
3026 struct btrfs_root *root,
3027 struct btrfs_path *path, int level)
3028{
3029 struct btrfs_fs_info *fs_info = root->fs_info;
3030 struct extent_buffer *c;
3031 struct extent_buffer *split;
3032 struct btrfs_disk_key disk_key;
3033 int mid;
3034 int ret;
3035 u32 c_nritems;
3036
3037 c = path->nodes[level];
3038 WARN_ON(btrfs_header_generation(c) != trans->transid);
3039 if (c == root->node) {
3040 /*
3041 * trying to split the root, lets make a new one
3042 *
3043 * tree mod log: We don't log_removal old root in
3044 * insert_new_root, because that root buffer will be kept as a
3045 * normal node. We are going to log removal of half of the
3046 * elements below with btrfs_tree_mod_log_eb_copy(). We're
3047 * holding a tree lock on the buffer, which is why we cannot
3048 * race with other tree_mod_log users.
3049 */
3050 ret = insert_new_root(trans, root, path, level + 1);
3051 if (ret)
3052 return ret;
3053 } else {
3054 ret = push_nodes_for_insert(trans, root, path, level);
3055 c = path->nodes[level];
3056 if (!ret && btrfs_header_nritems(c) <
3057 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
3058 return 0;
3059 if (ret < 0)
3060 return ret;
3061 }
3062
3063 c_nritems = btrfs_header_nritems(c);
3064 mid = (c_nritems + 1) / 2;
3065 btrfs_node_key(c, &disk_key, mid);
3066
3067 split = btrfs_alloc_tree_block(trans, root, 0, btrfs_root_id(root),
3068 &disk_key, level, c->start, 0,
3069 0, BTRFS_NESTING_SPLIT);
3070 if (IS_ERR(split))
3071 return PTR_ERR(split);
3072
3073 root_add_used_bytes(root);
3074 ASSERT(btrfs_header_level(c) == level);
3075
3076 ret = btrfs_tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
3077 if (ret) {
3078 btrfs_tree_unlock(split);
3079 free_extent_buffer(split);
3080 btrfs_abort_transaction(trans, ret);
3081 return ret;
3082 }
3083 copy_extent_buffer(split, c,
3084 btrfs_node_key_ptr_offset(split, 0),
3085 btrfs_node_key_ptr_offset(c, mid),
3086 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3087 btrfs_set_header_nritems(split, c_nritems - mid);
3088 btrfs_set_header_nritems(c, mid);
3089
3090 btrfs_mark_buffer_dirty(trans, c);
3091 btrfs_mark_buffer_dirty(trans, split);
3092
3093 ret = insert_ptr(trans, path, &disk_key, split->start,
3094 path->slots[level + 1] + 1, level + 1);
3095 if (ret < 0) {
3096 btrfs_tree_unlock(split);
3097 free_extent_buffer(split);
3098 return ret;
3099 }
3100
3101 if (path->slots[level] >= mid) {
3102 path->slots[level] -= mid;
3103 btrfs_tree_unlock(c);
3104 free_extent_buffer(c);
3105 path->nodes[level] = split;
3106 path->slots[level + 1] += 1;
3107 } else {
3108 btrfs_tree_unlock(split);
3109 free_extent_buffer(split);
3110 }
3111 return 0;
3112}
3113
3114/*
3115 * how many bytes are required to store the items in a leaf. start
3116 * and nr indicate which items in the leaf to check. This totals up the
3117 * space used both by the item structs and the item data
3118 */
3119static int leaf_space_used(const struct extent_buffer *l, int start, int nr)
3120{
3121 int data_len;
3122 int nritems = btrfs_header_nritems(l);
3123 int end = min(nritems, start + nr) - 1;
3124
3125 if (!nr)
3126 return 0;
3127 data_len = btrfs_item_offset(l, start) + btrfs_item_size(l, start);
3128 data_len = data_len - btrfs_item_offset(l, end);
3129 data_len += sizeof(struct btrfs_item) * nr;
3130 WARN_ON(data_len < 0);
3131 return data_len;
3132}
3133
3134/*
3135 * The space between the end of the leaf items and
3136 * the start of the leaf data. IOW, how much room
3137 * the leaf has left for both items and data
3138 */
3139int btrfs_leaf_free_space(const struct extent_buffer *leaf)
3140{
3141 struct btrfs_fs_info *fs_info = leaf->fs_info;
3142 int nritems = btrfs_header_nritems(leaf);
3143 int ret;
3144
3145 ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
3146 if (ret < 0) {
3147 btrfs_crit(fs_info,
3148 "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3149 ret,
3150 (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
3151 leaf_space_used(leaf, 0, nritems), nritems);
3152 }
3153 return ret;
3154}
3155
3156/*
3157 * min slot controls the lowest index we're willing to push to the
3158 * right. We'll push up to and including min_slot, but no lower
3159 */
3160static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
3161 struct btrfs_path *path,
3162 int data_size, int empty,
3163 struct extent_buffer *right,
3164 int free_space, u32 left_nritems,
3165 u32 min_slot)
3166{
3167 struct btrfs_fs_info *fs_info = right->fs_info;
3168 struct extent_buffer *left = path->nodes[0];
3169 struct extent_buffer *upper = path->nodes[1];
3170 struct btrfs_map_token token;
3171 struct btrfs_disk_key disk_key;
3172 int slot;
3173 u32 i;
3174 int push_space = 0;
3175 int push_items = 0;
3176 u32 nr;
3177 u32 right_nritems;
3178 u32 data_end;
3179 u32 this_item_size;
3180
3181 if (empty)
3182 nr = 0;
3183 else
3184 nr = max_t(u32, 1, min_slot);
3185
3186 if (path->slots[0] >= left_nritems)
3187 push_space += data_size;
3188
3189 slot = path->slots[1];
3190 i = left_nritems - 1;
3191 while (i >= nr) {
3192 if (!empty && push_items > 0) {
3193 if (path->slots[0] > i)
3194 break;
3195 if (path->slots[0] == i) {
3196 int space = btrfs_leaf_free_space(left);
3197
3198 if (space + push_space * 2 > free_space)
3199 break;
3200 }
3201 }
3202
3203 if (path->slots[0] == i)
3204 push_space += data_size;
3205
3206 this_item_size = btrfs_item_size(left, i);
3207 if (this_item_size + sizeof(struct btrfs_item) +
3208 push_space > free_space)
3209 break;
3210
3211 push_items++;
3212 push_space += this_item_size + sizeof(struct btrfs_item);
3213 if (i == 0)
3214 break;
3215 i--;
3216 }
3217
3218 if (push_items == 0)
3219 goto out_unlock;
3220
3221 WARN_ON(!empty && push_items == left_nritems);
3222
3223 /* push left to right */
3224 right_nritems = btrfs_header_nritems(right);
3225
3226 push_space = btrfs_item_data_end(left, left_nritems - push_items);
3227 push_space -= leaf_data_end(left);
3228
3229 /* make room in the right data area */
3230 data_end = leaf_data_end(right);
3231 memmove_leaf_data(right, data_end - push_space, data_end,
3232 BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
3233
3234 /* copy from the left data area */
3235 copy_leaf_data(right, left, BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3236 leaf_data_end(left), push_space);
3237
3238 memmove_leaf_items(right, push_items, 0, right_nritems);
3239
3240 /* copy the items from left to right */
3241 copy_leaf_items(right, left, 0, left_nritems - push_items, push_items);
3242
3243 /* update the item pointers */
3244 btrfs_init_map_token(&token, right);
3245 right_nritems += push_items;
3246 btrfs_set_header_nritems(right, right_nritems);
3247 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3248 for (i = 0; i < right_nritems; i++) {
3249 push_space -= btrfs_token_item_size(&token, i);
3250 btrfs_set_token_item_offset(&token, i, push_space);
3251 }
3252
3253 left_nritems -= push_items;
3254 btrfs_set_header_nritems(left, left_nritems);
3255
3256 if (left_nritems)
3257 btrfs_mark_buffer_dirty(trans, left);
3258 else
3259 btrfs_clear_buffer_dirty(trans, left);
3260
3261 btrfs_mark_buffer_dirty(trans, right);
3262
3263 btrfs_item_key(right, &disk_key, 0);
3264 btrfs_set_node_key(upper, &disk_key, slot + 1);
3265 btrfs_mark_buffer_dirty(trans, upper);
3266
3267 /* then fixup the leaf pointer in the path */
3268 if (path->slots[0] >= left_nritems) {
3269 path->slots[0] -= left_nritems;
3270 if (btrfs_header_nritems(path->nodes[0]) == 0)
3271 btrfs_clear_buffer_dirty(trans, path->nodes[0]);
3272 btrfs_tree_unlock(path->nodes[0]);
3273 free_extent_buffer(path->nodes[0]);
3274 path->nodes[0] = right;
3275 path->slots[1] += 1;
3276 } else {
3277 btrfs_tree_unlock(right);
3278 free_extent_buffer(right);
3279 }
3280 return 0;
3281
3282out_unlock:
3283 btrfs_tree_unlock(right);
3284 free_extent_buffer(right);
3285 return 1;
3286}
3287
3288/*
3289 * push some data in the path leaf to the right, trying to free up at
3290 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3291 *
3292 * returns 1 if the push failed because the other node didn't have enough
3293 * room, 0 if everything worked out and < 0 if there were major errors.
3294 *
3295 * this will push starting from min_slot to the end of the leaf. It won't
3296 * push any slot lower than min_slot
3297 */
3298static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3299 *root, struct btrfs_path *path,
3300 int min_data_size, int data_size,
3301 int empty, u32 min_slot)
3302{
3303 struct extent_buffer *left = path->nodes[0];
3304 struct extent_buffer *right;
3305 struct extent_buffer *upper;
3306 int slot;
3307 int free_space;
3308 u32 left_nritems;
3309 int ret;
3310
3311 if (!path->nodes[1])
3312 return 1;
3313
3314 slot = path->slots[1];
3315 upper = path->nodes[1];
3316 if (slot >= btrfs_header_nritems(upper) - 1)
3317 return 1;
3318
3319 btrfs_assert_tree_write_locked(path->nodes[1]);
3320
3321 right = btrfs_read_node_slot(upper, slot + 1);
3322 if (IS_ERR(right))
3323 return PTR_ERR(right);
3324
3325 btrfs_tree_lock_nested(right, BTRFS_NESTING_RIGHT);
3326
3327 free_space = btrfs_leaf_free_space(right);
3328 if (free_space < data_size)
3329 goto out_unlock;
3330
3331 ret = btrfs_cow_block(trans, root, right, upper,
3332 slot + 1, &right, BTRFS_NESTING_RIGHT_COW);
3333 if (ret)
3334 goto out_unlock;
3335
3336 left_nritems = btrfs_header_nritems(left);
3337 if (left_nritems == 0)
3338 goto out_unlock;
3339
3340 if (check_sibling_keys(left, right)) {
3341 ret = -EUCLEAN;
3342 btrfs_abort_transaction(trans, ret);
3343 btrfs_tree_unlock(right);
3344 free_extent_buffer(right);
3345 return ret;
3346 }
3347 if (path->slots[0] == left_nritems && !empty) {
3348 /* Key greater than all keys in the leaf, right neighbor has
3349 * enough room for it and we're not emptying our leaf to delete
3350 * it, therefore use right neighbor to insert the new item and
3351 * no need to touch/dirty our left leaf. */
3352 btrfs_tree_unlock(left);
3353 free_extent_buffer(left);
3354 path->nodes[0] = right;
3355 path->slots[0] = 0;
3356 path->slots[1]++;
3357 return 0;
3358 }
3359
3360 return __push_leaf_right(trans, path, min_data_size, empty, right,
3361 free_space, left_nritems, min_slot);
3362out_unlock:
3363 btrfs_tree_unlock(right);
3364 free_extent_buffer(right);
3365 return 1;
3366}
3367
3368/*
3369 * push some data in the path leaf to the left, trying to free up at
3370 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3371 *
3372 * max_slot can put a limit on how far into the leaf we'll push items. The
3373 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3374 * items
3375 */
3376static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
3377 struct btrfs_path *path, int data_size,
3378 int empty, struct extent_buffer *left,
3379 int free_space, u32 right_nritems,
3380 u32 max_slot)
3381{
3382 struct btrfs_fs_info *fs_info = left->fs_info;
3383 struct btrfs_disk_key disk_key;
3384 struct extent_buffer *right = path->nodes[0];
3385 int i;
3386 int push_space = 0;
3387 int push_items = 0;
3388 u32 old_left_nritems;
3389 u32 nr;
3390 int ret = 0;
3391 u32 this_item_size;
3392 u32 old_left_item_size;
3393 struct btrfs_map_token token;
3394
3395 if (empty)
3396 nr = min(right_nritems, max_slot);
3397 else
3398 nr = min(right_nritems - 1, max_slot);
3399
3400 for (i = 0; i < nr; i++) {
3401 if (!empty && push_items > 0) {
3402 if (path->slots[0] < i)
3403 break;
3404 if (path->slots[0] == i) {
3405 int space = btrfs_leaf_free_space(right);
3406
3407 if (space + push_space * 2 > free_space)
3408 break;
3409 }
3410 }
3411
3412 if (path->slots[0] == i)
3413 push_space += data_size;
3414
3415 this_item_size = btrfs_item_size(right, i);
3416 if (this_item_size + sizeof(struct btrfs_item) + push_space >
3417 free_space)
3418 break;
3419
3420 push_items++;
3421 push_space += this_item_size + sizeof(struct btrfs_item);
3422 }
3423
3424 if (push_items == 0) {
3425 ret = 1;
3426 goto out;
3427 }
3428 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3429
3430 /* push data from right to left */
3431 copy_leaf_items(left, right, btrfs_header_nritems(left), 0, push_items);
3432
3433 push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3434 btrfs_item_offset(right, push_items - 1);
3435
3436 copy_leaf_data(left, right, leaf_data_end(left) - push_space,
3437 btrfs_item_offset(right, push_items - 1), push_space);
3438 old_left_nritems = btrfs_header_nritems(left);
3439 BUG_ON(old_left_nritems <= 0);
3440
3441 btrfs_init_map_token(&token, left);
3442 old_left_item_size = btrfs_item_offset(left, old_left_nritems - 1);
3443 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3444 u32 ioff;
3445
3446 ioff = btrfs_token_item_offset(&token, i);
3447 btrfs_set_token_item_offset(&token, i,
3448 ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size));
3449 }
3450 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3451
3452 /* fixup right node */
3453 if (push_items > right_nritems)
3454 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3455 right_nritems);
3456
3457 if (push_items < right_nritems) {
3458 push_space = btrfs_item_offset(right, push_items - 1) -
3459 leaf_data_end(right);
3460 memmove_leaf_data(right,
3461 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3462 leaf_data_end(right), push_space);
3463
3464 memmove_leaf_items(right, 0, push_items,
3465 btrfs_header_nritems(right) - push_items);
3466 }
3467
3468 btrfs_init_map_token(&token, right);
3469 right_nritems -= push_items;
3470 btrfs_set_header_nritems(right, right_nritems);
3471 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3472 for (i = 0; i < right_nritems; i++) {
3473 push_space = push_space - btrfs_token_item_size(&token, i);
3474 btrfs_set_token_item_offset(&token, i, push_space);
3475 }
3476
3477 btrfs_mark_buffer_dirty(trans, left);
3478 if (right_nritems)
3479 btrfs_mark_buffer_dirty(trans, right);
3480 else
3481 btrfs_clear_buffer_dirty(trans, right);
3482
3483 btrfs_item_key(right, &disk_key, 0);
3484 fixup_low_keys(trans, path, &disk_key, 1);
3485
3486 /* then fixup the leaf pointer in the path */
3487 if (path->slots[0] < push_items) {
3488 path->slots[0] += old_left_nritems;
3489 btrfs_tree_unlock(path->nodes[0]);
3490 free_extent_buffer(path->nodes[0]);
3491 path->nodes[0] = left;
3492 path->slots[1] -= 1;
3493 } else {
3494 btrfs_tree_unlock(left);
3495 free_extent_buffer(left);
3496 path->slots[0] -= push_items;
3497 }
3498 BUG_ON(path->slots[0] < 0);
3499 return ret;
3500out:
3501 btrfs_tree_unlock(left);
3502 free_extent_buffer(left);
3503 return ret;
3504}
3505
3506/*
3507 * push some data in the path leaf to the left, trying to free up at
3508 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3509 *
3510 * max_slot can put a limit on how far into the leaf we'll push items. The
3511 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3512 * items
3513 */
3514static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3515 *root, struct btrfs_path *path, int min_data_size,
3516 int data_size, int empty, u32 max_slot)
3517{
3518 struct extent_buffer *right = path->nodes[0];
3519 struct extent_buffer *left;
3520 int slot;
3521 int free_space;
3522 u32 right_nritems;
3523 int ret = 0;
3524
3525 slot = path->slots[1];
3526 if (slot == 0)
3527 return 1;
3528 if (!path->nodes[1])
3529 return 1;
3530
3531 right_nritems = btrfs_header_nritems(right);
3532 if (right_nritems == 0)
3533 return 1;
3534
3535 btrfs_assert_tree_write_locked(path->nodes[1]);
3536
3537 left = btrfs_read_node_slot(path->nodes[1], slot - 1);
3538 if (IS_ERR(left))
3539 return PTR_ERR(left);
3540
3541 btrfs_tree_lock_nested(left, BTRFS_NESTING_LEFT);
3542
3543 free_space = btrfs_leaf_free_space(left);
3544 if (free_space < data_size) {
3545 ret = 1;
3546 goto out;
3547 }
3548
3549 ret = btrfs_cow_block(trans, root, left,
3550 path->nodes[1], slot - 1, &left,
3551 BTRFS_NESTING_LEFT_COW);
3552 if (ret) {
3553 /* we hit -ENOSPC, but it isn't fatal here */
3554 if (ret == -ENOSPC)
3555 ret = 1;
3556 goto out;
3557 }
3558
3559 if (check_sibling_keys(left, right)) {
3560 ret = -EUCLEAN;
3561 btrfs_abort_transaction(trans, ret);
3562 goto out;
3563 }
3564 return __push_leaf_left(trans, path, min_data_size, empty, left,
3565 free_space, right_nritems, max_slot);
3566out:
3567 btrfs_tree_unlock(left);
3568 free_extent_buffer(left);
3569 return ret;
3570}
3571
3572/*
3573 * split the path's leaf in two, making sure there is at least data_size
3574 * available for the resulting leaf level of the path.
3575 */
3576static noinline int copy_for_split(struct btrfs_trans_handle *trans,
3577 struct btrfs_path *path,
3578 struct extent_buffer *l,
3579 struct extent_buffer *right,
3580 int slot, int mid, int nritems)
3581{
3582 struct btrfs_fs_info *fs_info = trans->fs_info;
3583 int data_copy_size;
3584 int rt_data_off;
3585 int i;
3586 int ret;
3587 struct btrfs_disk_key disk_key;
3588 struct btrfs_map_token token;
3589
3590 nritems = nritems - mid;
3591 btrfs_set_header_nritems(right, nritems);
3592 data_copy_size = btrfs_item_data_end(l, mid) - leaf_data_end(l);
3593
3594 copy_leaf_items(right, l, 0, mid, nritems);
3595
3596 copy_leaf_data(right, l, BTRFS_LEAF_DATA_SIZE(fs_info) - data_copy_size,
3597 leaf_data_end(l), data_copy_size);
3598
3599 rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_data_end(l, mid);
3600
3601 btrfs_init_map_token(&token, right);
3602 for (i = 0; i < nritems; i++) {
3603 u32 ioff;
3604
3605 ioff = btrfs_token_item_offset(&token, i);
3606 btrfs_set_token_item_offset(&token, i, ioff + rt_data_off);
3607 }
3608
3609 btrfs_set_header_nritems(l, mid);
3610 btrfs_item_key(right, &disk_key, 0);
3611 ret = insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
3612 if (ret < 0)
3613 return ret;
3614
3615 btrfs_mark_buffer_dirty(trans, right);
3616 btrfs_mark_buffer_dirty(trans, l);
3617 BUG_ON(path->slots[0] != slot);
3618
3619 if (mid <= slot) {
3620 btrfs_tree_unlock(path->nodes[0]);
3621 free_extent_buffer(path->nodes[0]);
3622 path->nodes[0] = right;
3623 path->slots[0] -= mid;
3624 path->slots[1] += 1;
3625 } else {
3626 btrfs_tree_unlock(right);
3627 free_extent_buffer(right);
3628 }
3629
3630 BUG_ON(path->slots[0] < 0);
3631
3632 return 0;
3633}
3634
3635/*
3636 * double splits happen when we need to insert a big item in the middle
3637 * of a leaf. A double split can leave us with 3 mostly empty leaves:
3638 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
3639 * A B C
3640 *
3641 * We avoid this by trying to push the items on either side of our target
3642 * into the adjacent leaves. If all goes well we can avoid the double split
3643 * completely.
3644 */
3645static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
3646 struct btrfs_root *root,
3647 struct btrfs_path *path,
3648 int data_size)
3649{
3650 int ret;
3651 int progress = 0;
3652 int slot;
3653 u32 nritems;
3654 int space_needed = data_size;
3655
3656 slot = path->slots[0];
3657 if (slot < btrfs_header_nritems(path->nodes[0]))
3658 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3659
3660 /*
3661 * try to push all the items after our slot into the
3662 * right leaf
3663 */
3664 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
3665 if (ret < 0)
3666 return ret;
3667
3668 if (ret == 0)
3669 progress++;
3670
3671 nritems = btrfs_header_nritems(path->nodes[0]);
3672 /*
3673 * our goal is to get our slot at the start or end of a leaf. If
3674 * we've done so we're done
3675 */
3676 if (path->slots[0] == 0 || path->slots[0] == nritems)
3677 return 0;
3678
3679 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3680 return 0;
3681
3682 /* try to push all the items before our slot into the next leaf */
3683 slot = path->slots[0];
3684 space_needed = data_size;
3685 if (slot > 0)
3686 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3687 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
3688 if (ret < 0)
3689 return ret;
3690
3691 if (ret == 0)
3692 progress++;
3693
3694 if (progress)
3695 return 0;
3696 return 1;
3697}
3698
3699/*
3700 * split the path's leaf in two, making sure there is at least data_size
3701 * available for the resulting leaf level of the path.
3702 *
3703 * returns 0 if all went well and < 0 on failure.
3704 */
3705static noinline int split_leaf(struct btrfs_trans_handle *trans,
3706 struct btrfs_root *root,
3707 const struct btrfs_key *ins_key,
3708 struct btrfs_path *path, int data_size,
3709 int extend)
3710{
3711 struct btrfs_disk_key disk_key;
3712 struct extent_buffer *l;
3713 u32 nritems;
3714 int mid;
3715 int slot;
3716 struct extent_buffer *right;
3717 struct btrfs_fs_info *fs_info = root->fs_info;
3718 int ret = 0;
3719 int wret;
3720 int split;
3721 int num_doubles = 0;
3722 int tried_avoid_double = 0;
3723
3724 l = path->nodes[0];
3725 slot = path->slots[0];
3726 if (extend && data_size + btrfs_item_size(l, slot) +
3727 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
3728 return -EOVERFLOW;
3729
3730 /* first try to make some room by pushing left and right */
3731 if (data_size && path->nodes[1]) {
3732 int space_needed = data_size;
3733
3734 if (slot < btrfs_header_nritems(l))
3735 space_needed -= btrfs_leaf_free_space(l);
3736
3737 wret = push_leaf_right(trans, root, path, space_needed,
3738 space_needed, 0, 0);
3739 if (wret < 0)
3740 return wret;
3741 if (wret) {
3742 space_needed = data_size;
3743 if (slot > 0)
3744 space_needed -= btrfs_leaf_free_space(l);
3745 wret = push_leaf_left(trans, root, path, space_needed,
3746 space_needed, 0, (u32)-1);
3747 if (wret < 0)
3748 return wret;
3749 }
3750 l = path->nodes[0];
3751
3752 /* did the pushes work? */
3753 if (btrfs_leaf_free_space(l) >= data_size)
3754 return 0;
3755 }
3756
3757 if (!path->nodes[1]) {
3758 ret = insert_new_root(trans, root, path, 1);
3759 if (ret)
3760 return ret;
3761 }
3762again:
3763 split = 1;
3764 l = path->nodes[0];
3765 slot = path->slots[0];
3766 nritems = btrfs_header_nritems(l);
3767 mid = (nritems + 1) / 2;
3768
3769 if (mid <= slot) {
3770 if (nritems == 1 ||
3771 leaf_space_used(l, mid, nritems - mid) + data_size >
3772 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3773 if (slot >= nritems) {
3774 split = 0;
3775 } else {
3776 mid = slot;
3777 if (mid != nritems &&
3778 leaf_space_used(l, mid, nritems - mid) +
3779 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3780 if (data_size && !tried_avoid_double)
3781 goto push_for_double;
3782 split = 2;
3783 }
3784 }
3785 }
3786 } else {
3787 if (leaf_space_used(l, 0, mid) + data_size >
3788 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3789 if (!extend && data_size && slot == 0) {
3790 split = 0;
3791 } else if ((extend || !data_size) && slot == 0) {
3792 mid = 1;
3793 } else {
3794 mid = slot;
3795 if (mid != nritems &&
3796 leaf_space_used(l, mid, nritems - mid) +
3797 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3798 if (data_size && !tried_avoid_double)
3799 goto push_for_double;
3800 split = 2;
3801 }
3802 }
3803 }
3804 }
3805
3806 if (split == 0)
3807 btrfs_cpu_key_to_disk(&disk_key, ins_key);
3808 else
3809 btrfs_item_key(l, &disk_key, mid);
3810
3811 /*
3812 * We have to about BTRFS_NESTING_NEW_ROOT here if we've done a double
3813 * split, because we're only allowed to have MAX_LOCKDEP_SUBCLASSES
3814 * subclasses, which is 8 at the time of this patch, and we've maxed it
3815 * out. In the future we could add a
3816 * BTRFS_NESTING_SPLIT_THE_SPLITTENING if we need to, but for now just
3817 * use BTRFS_NESTING_NEW_ROOT.
3818 */
3819 right = btrfs_alloc_tree_block(trans, root, 0, btrfs_root_id(root),
3820 &disk_key, 0, l->start, 0, 0,
3821 num_doubles ? BTRFS_NESTING_NEW_ROOT :
3822 BTRFS_NESTING_SPLIT);
3823 if (IS_ERR(right))
3824 return PTR_ERR(right);
3825
3826 root_add_used_bytes(root);
3827
3828 if (split == 0) {
3829 if (mid <= slot) {
3830 btrfs_set_header_nritems(right, 0);
3831 ret = insert_ptr(trans, path, &disk_key,
3832 right->start, path->slots[1] + 1, 1);
3833 if (ret < 0) {
3834 btrfs_tree_unlock(right);
3835 free_extent_buffer(right);
3836 return ret;
3837 }
3838 btrfs_tree_unlock(path->nodes[0]);
3839 free_extent_buffer(path->nodes[0]);
3840 path->nodes[0] = right;
3841 path->slots[0] = 0;
3842 path->slots[1] += 1;
3843 } else {
3844 btrfs_set_header_nritems(right, 0);
3845 ret = insert_ptr(trans, path, &disk_key,
3846 right->start, path->slots[1], 1);
3847 if (ret < 0) {
3848 btrfs_tree_unlock(right);
3849 free_extent_buffer(right);
3850 return ret;
3851 }
3852 btrfs_tree_unlock(path->nodes[0]);
3853 free_extent_buffer(path->nodes[0]);
3854 path->nodes[0] = right;
3855 path->slots[0] = 0;
3856 if (path->slots[1] == 0)
3857 fixup_low_keys(trans, path, &disk_key, 1);
3858 }
3859 /*
3860 * We create a new leaf 'right' for the required ins_len and
3861 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
3862 * the content of ins_len to 'right'.
3863 */
3864 return ret;
3865 }
3866
3867 ret = copy_for_split(trans, path, l, right, slot, mid, nritems);
3868 if (ret < 0) {
3869 btrfs_tree_unlock(right);
3870 free_extent_buffer(right);
3871 return ret;
3872 }
3873
3874 if (split == 2) {
3875 BUG_ON(num_doubles != 0);
3876 num_doubles++;
3877 goto again;
3878 }
3879
3880 return 0;
3881
3882push_for_double:
3883 push_for_double_split(trans, root, path, data_size);
3884 tried_avoid_double = 1;
3885 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3886 return 0;
3887 goto again;
3888}
3889
3890static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3891 struct btrfs_root *root,
3892 struct btrfs_path *path, int ins_len)
3893{
3894 struct btrfs_key key;
3895 struct extent_buffer *leaf;
3896 struct btrfs_file_extent_item *fi;
3897 u64 extent_len = 0;
3898 u32 item_size;
3899 int ret;
3900
3901 leaf = path->nodes[0];
3902 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3903
3904 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3905 key.type != BTRFS_EXTENT_CSUM_KEY);
3906
3907 if (btrfs_leaf_free_space(leaf) >= ins_len)
3908 return 0;
3909
3910 item_size = btrfs_item_size(leaf, path->slots[0]);
3911 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3912 fi = btrfs_item_ptr(leaf, path->slots[0],
3913 struct btrfs_file_extent_item);
3914 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3915 }
3916 btrfs_release_path(path);
3917
3918 path->keep_locks = 1;
3919 path->search_for_split = 1;
3920 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3921 path->search_for_split = 0;
3922 if (ret > 0)
3923 ret = -EAGAIN;
3924 if (ret < 0)
3925 goto err;
3926
3927 ret = -EAGAIN;
3928 leaf = path->nodes[0];
3929 /* if our item isn't there, return now */
3930 if (item_size != btrfs_item_size(leaf, path->slots[0]))
3931 goto err;
3932
3933 /* the leaf has changed, it now has room. return now */
3934 if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
3935 goto err;
3936
3937 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3938 fi = btrfs_item_ptr(leaf, path->slots[0],
3939 struct btrfs_file_extent_item);
3940 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3941 goto err;
3942 }
3943
3944 ret = split_leaf(trans, root, &key, path, ins_len, 1);
3945 if (ret)
3946 goto err;
3947
3948 path->keep_locks = 0;
3949 btrfs_unlock_up_safe(path, 1);
3950 return 0;
3951err:
3952 path->keep_locks = 0;
3953 return ret;
3954}
3955
3956static noinline int split_item(struct btrfs_trans_handle *trans,
3957 struct btrfs_path *path,
3958 const struct btrfs_key *new_key,
3959 unsigned long split_offset)
3960{
3961 struct extent_buffer *leaf;
3962 int orig_slot, slot;
3963 char *buf;
3964 u32 nritems;
3965 u32 item_size;
3966 u32 orig_offset;
3967 struct btrfs_disk_key disk_key;
3968
3969 leaf = path->nodes[0];
3970 /*
3971 * Shouldn't happen because the caller must have previously called
3972 * setup_leaf_for_split() to make room for the new item in the leaf.
3973 */
3974 if (WARN_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item)))
3975 return -ENOSPC;
3976
3977 orig_slot = path->slots[0];
3978 orig_offset = btrfs_item_offset(leaf, path->slots[0]);
3979 item_size = btrfs_item_size(leaf, path->slots[0]);
3980
3981 buf = kmalloc(item_size, GFP_NOFS);
3982 if (!buf)
3983 return -ENOMEM;
3984
3985 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3986 path->slots[0]), item_size);
3987
3988 slot = path->slots[0] + 1;
3989 nritems = btrfs_header_nritems(leaf);
3990 if (slot != nritems) {
3991 /* shift the items */
3992 memmove_leaf_items(leaf, slot + 1, slot, nritems - slot);
3993 }
3994
3995 btrfs_cpu_key_to_disk(&disk_key, new_key);
3996 btrfs_set_item_key(leaf, &disk_key, slot);
3997
3998 btrfs_set_item_offset(leaf, slot, orig_offset);
3999 btrfs_set_item_size(leaf, slot, item_size - split_offset);
4000
4001 btrfs_set_item_offset(leaf, orig_slot,
4002 orig_offset + item_size - split_offset);
4003 btrfs_set_item_size(leaf, orig_slot, split_offset);
4004
4005 btrfs_set_header_nritems(leaf, nritems + 1);
4006
4007 /* write the data for the start of the original item */
4008 write_extent_buffer(leaf, buf,
4009 btrfs_item_ptr_offset(leaf, path->slots[0]),
4010 split_offset);
4011
4012 /* write the data for the new item */
4013 write_extent_buffer(leaf, buf + split_offset,
4014 btrfs_item_ptr_offset(leaf, slot),
4015 item_size - split_offset);
4016 btrfs_mark_buffer_dirty(trans, leaf);
4017
4018 BUG_ON(btrfs_leaf_free_space(leaf) < 0);
4019 kfree(buf);
4020 return 0;
4021}
4022
4023/*
4024 * This function splits a single item into two items,
4025 * giving 'new_key' to the new item and splitting the
4026 * old one at split_offset (from the start of the item).
4027 *
4028 * The path may be released by this operation. After
4029 * the split, the path is pointing to the old item. The
4030 * new item is going to be in the same node as the old one.
4031 *
4032 * Note, the item being split must be smaller enough to live alone on
4033 * a tree block with room for one extra struct btrfs_item
4034 *
4035 * This allows us to split the item in place, keeping a lock on the
4036 * leaf the entire time.
4037 */
4038int btrfs_split_item(struct btrfs_trans_handle *trans,
4039 struct btrfs_root *root,
4040 struct btrfs_path *path,
4041 const struct btrfs_key *new_key,
4042 unsigned long split_offset)
4043{
4044 int ret;
4045 ret = setup_leaf_for_split(trans, root, path,
4046 sizeof(struct btrfs_item));
4047 if (ret)
4048 return ret;
4049
4050 ret = split_item(trans, path, new_key, split_offset);
4051 return ret;
4052}
4053
4054/*
4055 * make the item pointed to by the path smaller. new_size indicates
4056 * how small to make it, and from_end tells us if we just chop bytes
4057 * off the end of the item or if we shift the item to chop bytes off
4058 * the front.
4059 */
4060void btrfs_truncate_item(struct btrfs_trans_handle *trans,
4061 const struct btrfs_path *path, u32 new_size, int from_end)
4062{
4063 int slot;
4064 struct extent_buffer *leaf;
4065 u32 nritems;
4066 unsigned int data_end;
4067 unsigned int old_data_start;
4068 unsigned int old_size;
4069 unsigned int size_diff;
4070 int i;
4071 struct btrfs_map_token token;
4072
4073 leaf = path->nodes[0];
4074 slot = path->slots[0];
4075
4076 old_size = btrfs_item_size(leaf, slot);
4077 if (old_size == new_size)
4078 return;
4079
4080 nritems = btrfs_header_nritems(leaf);
4081 data_end = leaf_data_end(leaf);
4082
4083 old_data_start = btrfs_item_offset(leaf, slot);
4084
4085 size_diff = old_size - new_size;
4086
4087 BUG_ON(slot < 0);
4088 BUG_ON(slot >= nritems);
4089
4090 /*
4091 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4092 */
4093 /* first correct the data pointers */
4094 btrfs_init_map_token(&token, leaf);
4095 for (i = slot; i < nritems; i++) {
4096 u32 ioff;
4097
4098 ioff = btrfs_token_item_offset(&token, i);
4099 btrfs_set_token_item_offset(&token, i, ioff + size_diff);
4100 }
4101
4102 /* shift the data */
4103 if (from_end) {
4104 memmove_leaf_data(leaf, data_end + size_diff, data_end,
4105 old_data_start + new_size - data_end);
4106 } else {
4107 struct btrfs_disk_key disk_key;
4108 u64 offset;
4109
4110 btrfs_item_key(leaf, &disk_key, slot);
4111
4112 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4113 unsigned long ptr;
4114 struct btrfs_file_extent_item *fi;
4115
4116 fi = btrfs_item_ptr(leaf, slot,
4117 struct btrfs_file_extent_item);
4118 fi = (struct btrfs_file_extent_item *)(
4119 (unsigned long)fi - size_diff);
4120
4121 if (btrfs_file_extent_type(leaf, fi) ==
4122 BTRFS_FILE_EXTENT_INLINE) {
4123 ptr = btrfs_item_ptr_offset(leaf, slot);
4124 memmove_extent_buffer(leaf, ptr,
4125 (unsigned long)fi,
4126 BTRFS_FILE_EXTENT_INLINE_DATA_START);
4127 }
4128 }
4129
4130 memmove_leaf_data(leaf, data_end + size_diff, data_end,
4131 old_data_start - data_end);
4132
4133 offset = btrfs_disk_key_offset(&disk_key);
4134 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4135 btrfs_set_item_key(leaf, &disk_key, slot);
4136 if (slot == 0)
4137 fixup_low_keys(trans, path, &disk_key, 1);
4138 }
4139
4140 btrfs_set_item_size(leaf, slot, new_size);
4141 btrfs_mark_buffer_dirty(trans, leaf);
4142
4143 if (btrfs_leaf_free_space(leaf) < 0) {
4144 btrfs_print_leaf(leaf);
4145 BUG();
4146 }
4147}
4148
4149/*
4150 * make the item pointed to by the path bigger, data_size is the added size.
4151 */
4152void btrfs_extend_item(struct btrfs_trans_handle *trans,
4153 const struct btrfs_path *path, u32 data_size)
4154{
4155 int slot;
4156 struct extent_buffer *leaf;
4157 u32 nritems;
4158 unsigned int data_end;
4159 unsigned int old_data;
4160 unsigned int old_size;
4161 int i;
4162 struct btrfs_map_token token;
4163
4164 leaf = path->nodes[0];
4165
4166 nritems = btrfs_header_nritems(leaf);
4167 data_end = leaf_data_end(leaf);
4168
4169 if (btrfs_leaf_free_space(leaf) < data_size) {
4170 btrfs_print_leaf(leaf);
4171 BUG();
4172 }
4173 slot = path->slots[0];
4174 old_data = btrfs_item_data_end(leaf, slot);
4175
4176 BUG_ON(slot < 0);
4177 if (slot >= nritems) {
4178 btrfs_print_leaf(leaf);
4179 btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
4180 slot, nritems);
4181 BUG();
4182 }
4183
4184 /*
4185 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4186 */
4187 /* first correct the data pointers */
4188 btrfs_init_map_token(&token, leaf);
4189 for (i = slot; i < nritems; i++) {
4190 u32 ioff;
4191
4192 ioff = btrfs_token_item_offset(&token, i);
4193 btrfs_set_token_item_offset(&token, i, ioff - data_size);
4194 }
4195
4196 /* shift the data */
4197 memmove_leaf_data(leaf, data_end - data_size, data_end,
4198 old_data - data_end);
4199
4200 data_end = old_data;
4201 old_size = btrfs_item_size(leaf, slot);
4202 btrfs_set_item_size(leaf, slot, old_size + data_size);
4203 btrfs_mark_buffer_dirty(trans, leaf);
4204
4205 if (btrfs_leaf_free_space(leaf) < 0) {
4206 btrfs_print_leaf(leaf);
4207 BUG();
4208 }
4209}
4210
4211/*
4212 * Make space in the node before inserting one or more items.
4213 *
4214 * @trans: transaction handle
4215 * @root: root we are inserting items to
4216 * @path: points to the leaf/slot where we are going to insert new items
4217 * @batch: information about the batch of items to insert
4218 *
4219 * Main purpose is to save stack depth by doing the bulk of the work in a
4220 * function that doesn't call btrfs_search_slot
4221 */
4222static void setup_items_for_insert(struct btrfs_trans_handle *trans,
4223 struct btrfs_root *root, struct btrfs_path *path,
4224 const struct btrfs_item_batch *batch)
4225{
4226 struct btrfs_fs_info *fs_info = root->fs_info;
4227 int i;
4228 u32 nritems;
4229 unsigned int data_end;
4230 struct btrfs_disk_key disk_key;
4231 struct extent_buffer *leaf;
4232 int slot;
4233 struct btrfs_map_token token;
4234 u32 total_size;
4235
4236 /*
4237 * Before anything else, update keys in the parent and other ancestors
4238 * if needed, then release the write locks on them, so that other tasks
4239 * can use them while we modify the leaf.
4240 */
4241 if (path->slots[0] == 0) {
4242 btrfs_cpu_key_to_disk(&disk_key, &batch->keys[0]);
4243 fixup_low_keys(trans, path, &disk_key, 1);
4244 }
4245 btrfs_unlock_up_safe(path, 1);
4246
4247 leaf = path->nodes[0];
4248 slot = path->slots[0];
4249
4250 nritems = btrfs_header_nritems(leaf);
4251 data_end = leaf_data_end(leaf);
4252 total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
4253
4254 if (btrfs_leaf_free_space(leaf) < total_size) {
4255 btrfs_print_leaf(leaf);
4256 btrfs_crit(fs_info, "not enough freespace need %u have %d",
4257 total_size, btrfs_leaf_free_space(leaf));
4258 BUG();
4259 }
4260
4261 btrfs_init_map_token(&token, leaf);
4262 if (slot != nritems) {
4263 unsigned int old_data = btrfs_item_data_end(leaf, slot);
4264
4265 if (old_data < data_end) {
4266 btrfs_print_leaf(leaf);
4267 btrfs_crit(fs_info,
4268 "item at slot %d with data offset %u beyond data end of leaf %u",
4269 slot, old_data, data_end);
4270 BUG();
4271 }
4272 /*
4273 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4274 */
4275 /* first correct the data pointers */
4276 for (i = slot; i < nritems; i++) {
4277 u32 ioff;
4278
4279 ioff = btrfs_token_item_offset(&token, i);
4280 btrfs_set_token_item_offset(&token, i,
4281 ioff - batch->total_data_size);
4282 }
4283 /* shift the items */
4284 memmove_leaf_items(leaf, slot + batch->nr, slot, nritems - slot);
4285
4286 /* shift the data */
4287 memmove_leaf_data(leaf, data_end - batch->total_data_size,
4288 data_end, old_data - data_end);
4289 data_end = old_data;
4290 }
4291
4292 /* setup the item for the new data */
4293 for (i = 0; i < batch->nr; i++) {
4294 btrfs_cpu_key_to_disk(&disk_key, &batch->keys[i]);
4295 btrfs_set_item_key(leaf, &disk_key, slot + i);
4296 data_end -= batch->data_sizes[i];
4297 btrfs_set_token_item_offset(&token, slot + i, data_end);
4298 btrfs_set_token_item_size(&token, slot + i, batch->data_sizes[i]);
4299 }
4300
4301 btrfs_set_header_nritems(leaf, nritems + batch->nr);
4302 btrfs_mark_buffer_dirty(trans, leaf);
4303
4304 if (btrfs_leaf_free_space(leaf) < 0) {
4305 btrfs_print_leaf(leaf);
4306 BUG();
4307 }
4308}
4309
4310/*
4311 * Insert a new item into a leaf.
4312 *
4313 * @trans: Transaction handle.
4314 * @root: The root of the btree.
4315 * @path: A path pointing to the target leaf and slot.
4316 * @key: The key of the new item.
4317 * @data_size: The size of the data associated with the new key.
4318 */
4319void btrfs_setup_item_for_insert(struct btrfs_trans_handle *trans,
4320 struct btrfs_root *root,
4321 struct btrfs_path *path,
4322 const struct btrfs_key *key,
4323 u32 data_size)
4324{
4325 struct btrfs_item_batch batch;
4326
4327 batch.keys = key;
4328 batch.data_sizes = &data_size;
4329 batch.total_data_size = data_size;
4330 batch.nr = 1;
4331
4332 setup_items_for_insert(trans, root, path, &batch);
4333}
4334
4335/*
4336 * Given a key and some data, insert items into the tree.
4337 * This does all the path init required, making room in the tree if needed.
4338 *
4339 * Returns: 0 on success
4340 * -EEXIST if the first key already exists
4341 * < 0 on other errors
4342 */
4343int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4344 struct btrfs_root *root,
4345 struct btrfs_path *path,
4346 const struct btrfs_item_batch *batch)
4347{
4348 int ret = 0;
4349 int slot;
4350 u32 total_size;
4351
4352 total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
4353 ret = btrfs_search_slot(trans, root, &batch->keys[0], path, total_size, 1);
4354 if (ret == 0)
4355 return -EEXIST;
4356 if (ret < 0)
4357 return ret;
4358
4359 slot = path->slots[0];
4360 BUG_ON(slot < 0);
4361
4362 setup_items_for_insert(trans, root, path, batch);
4363 return 0;
4364}
4365
4366/*
4367 * Given a key and some data, insert an item into the tree.
4368 * This does all the path init required, making room in the tree if needed.
4369 */
4370int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4371 const struct btrfs_key *cpu_key, void *data,
4372 u32 data_size)
4373{
4374 int ret = 0;
4375 struct btrfs_path *path;
4376 struct extent_buffer *leaf;
4377 unsigned long ptr;
4378
4379 path = btrfs_alloc_path();
4380 if (!path)
4381 return -ENOMEM;
4382 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4383 if (!ret) {
4384 leaf = path->nodes[0];
4385 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4386 write_extent_buffer(leaf, data, ptr, data_size);
4387 btrfs_mark_buffer_dirty(trans, leaf);
4388 }
4389 btrfs_free_path(path);
4390 return ret;
4391}
4392
4393/*
4394 * This function duplicates an item, giving 'new_key' to the new item.
4395 * It guarantees both items live in the same tree leaf and the new item is
4396 * contiguous with the original item.
4397 *
4398 * This allows us to split a file extent in place, keeping a lock on the leaf
4399 * the entire time.
4400 */
4401int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4402 struct btrfs_root *root,
4403 struct btrfs_path *path,
4404 const struct btrfs_key *new_key)
4405{
4406 struct extent_buffer *leaf;
4407 int ret;
4408 u32 item_size;
4409
4410 leaf = path->nodes[0];
4411 item_size = btrfs_item_size(leaf, path->slots[0]);
4412 ret = setup_leaf_for_split(trans, root, path,
4413 item_size + sizeof(struct btrfs_item));
4414 if (ret)
4415 return ret;
4416
4417 path->slots[0]++;
4418 btrfs_setup_item_for_insert(trans, root, path, new_key, item_size);
4419 leaf = path->nodes[0];
4420 memcpy_extent_buffer(leaf,
4421 btrfs_item_ptr_offset(leaf, path->slots[0]),
4422 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4423 item_size);
4424 return 0;
4425}
4426
4427/*
4428 * delete the pointer from a given node.
4429 *
4430 * the tree should have been previously balanced so the deletion does not
4431 * empty a node.
4432 *
4433 * This is exported for use inside btrfs-progs, don't un-export it.
4434 */
4435int btrfs_del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4436 struct btrfs_path *path, int level, int slot)
4437{
4438 struct extent_buffer *parent = path->nodes[level];
4439 u32 nritems;
4440 int ret;
4441
4442 nritems = btrfs_header_nritems(parent);
4443 if (slot != nritems - 1) {
4444 if (level) {
4445 ret = btrfs_tree_mod_log_insert_move(parent, slot,
4446 slot + 1, nritems - slot - 1);
4447 if (ret < 0) {
4448 btrfs_abort_transaction(trans, ret);
4449 return ret;
4450 }
4451 }
4452 memmove_extent_buffer(parent,
4453 btrfs_node_key_ptr_offset(parent, slot),
4454 btrfs_node_key_ptr_offset(parent, slot + 1),
4455 sizeof(struct btrfs_key_ptr) *
4456 (nritems - slot - 1));
4457 } else if (level) {
4458 ret = btrfs_tree_mod_log_insert_key(parent, slot,
4459 BTRFS_MOD_LOG_KEY_REMOVE);
4460 if (ret < 0) {
4461 btrfs_abort_transaction(trans, ret);
4462 return ret;
4463 }
4464 }
4465
4466 nritems--;
4467 btrfs_set_header_nritems(parent, nritems);
4468 if (nritems == 0 && parent == root->node) {
4469 BUG_ON(btrfs_header_level(root->node) != 1);
4470 /* just turn the root into a leaf and break */
4471 btrfs_set_header_level(root->node, 0);
4472 } else if (slot == 0) {
4473 struct btrfs_disk_key disk_key;
4474
4475 btrfs_node_key(parent, &disk_key, 0);
4476 fixup_low_keys(trans, path, &disk_key, level + 1);
4477 }
4478 btrfs_mark_buffer_dirty(trans, parent);
4479 return 0;
4480}
4481
4482/*
4483 * a helper function to delete the leaf pointed to by path->slots[1] and
4484 * path->nodes[1].
4485 *
4486 * This deletes the pointer in path->nodes[1] and frees the leaf
4487 * block extent. zero is returned if it all worked out, < 0 otherwise.
4488 *
4489 * The path must have already been setup for deleting the leaf, including
4490 * all the proper balancing. path->nodes[1] must be locked.
4491 */
4492static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
4493 struct btrfs_root *root,
4494 struct btrfs_path *path,
4495 struct extent_buffer *leaf)
4496{
4497 int ret;
4498
4499 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4500 ret = btrfs_del_ptr(trans, root, path, 1, path->slots[1]);
4501 if (ret < 0)
4502 return ret;
4503
4504 /*
4505 * btrfs_free_extent is expensive, we want to make sure we
4506 * aren't holding any locks when we call it
4507 */
4508 btrfs_unlock_up_safe(path, 0);
4509
4510 root_sub_used_bytes(root);
4511
4512 atomic_inc(&leaf->refs);
4513 ret = btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
4514 free_extent_buffer_stale(leaf);
4515 if (ret < 0)
4516 btrfs_abort_transaction(trans, ret);
4517
4518 return ret;
4519}
4520/*
4521 * delete the item at the leaf level in path. If that empties
4522 * the leaf, remove it from the tree
4523 */
4524int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4525 struct btrfs_path *path, int slot, int nr)
4526{
4527 struct btrfs_fs_info *fs_info = root->fs_info;
4528 struct extent_buffer *leaf;
4529 int ret = 0;
4530 int wret;
4531 u32 nritems;
4532
4533 leaf = path->nodes[0];
4534 nritems = btrfs_header_nritems(leaf);
4535
4536 if (slot + nr != nritems) {
4537 const u32 last_off = btrfs_item_offset(leaf, slot + nr - 1);
4538 const int data_end = leaf_data_end(leaf);
4539 struct btrfs_map_token token;
4540 u32 dsize = 0;
4541 int i;
4542
4543 for (i = 0; i < nr; i++)
4544 dsize += btrfs_item_size(leaf, slot + i);
4545
4546 memmove_leaf_data(leaf, data_end + dsize, data_end,
4547 last_off - data_end);
4548
4549 btrfs_init_map_token(&token, leaf);
4550 for (i = slot + nr; i < nritems; i++) {
4551 u32 ioff;
4552
4553 ioff = btrfs_token_item_offset(&token, i);
4554 btrfs_set_token_item_offset(&token, i, ioff + dsize);
4555 }
4556
4557 memmove_leaf_items(leaf, slot, slot + nr, nritems - slot - nr);
4558 }
4559 btrfs_set_header_nritems(leaf, nritems - nr);
4560 nritems -= nr;
4561
4562 /* delete the leaf if we've emptied it */
4563 if (nritems == 0) {
4564 if (leaf == root->node) {
4565 btrfs_set_header_level(leaf, 0);
4566 } else {
4567 btrfs_clear_buffer_dirty(trans, leaf);
4568 ret = btrfs_del_leaf(trans, root, path, leaf);
4569 if (ret < 0)
4570 return ret;
4571 }
4572 } else {
4573 int used = leaf_space_used(leaf, 0, nritems);
4574 if (slot == 0) {
4575 struct btrfs_disk_key disk_key;
4576
4577 btrfs_item_key(leaf, &disk_key, 0);
4578 fixup_low_keys(trans, path, &disk_key, 1);
4579 }
4580
4581 /*
4582 * Try to delete the leaf if it is mostly empty. We do this by
4583 * trying to move all its items into its left and right neighbours.
4584 * If we can't move all the items, then we don't delete it - it's
4585 * not ideal, but future insertions might fill the leaf with more
4586 * items, or items from other leaves might be moved later into our
4587 * leaf due to deletions on those leaves.
4588 */
4589 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
4590 u32 min_push_space;
4591
4592 /* push_leaf_left fixes the path.
4593 * make sure the path still points to our leaf
4594 * for possible call to btrfs_del_ptr below
4595 */
4596 slot = path->slots[1];
4597 atomic_inc(&leaf->refs);
4598 /*
4599 * We want to be able to at least push one item to the
4600 * left neighbour leaf, and that's the first item.
4601 */
4602 min_push_space = sizeof(struct btrfs_item) +
4603 btrfs_item_size(leaf, 0);
4604 wret = push_leaf_left(trans, root, path, 0,
4605 min_push_space, 1, (u32)-1);
4606 if (wret < 0 && wret != -ENOSPC)
4607 ret = wret;
4608
4609 if (path->nodes[0] == leaf &&
4610 btrfs_header_nritems(leaf)) {
4611 /*
4612 * If we were not able to push all items from our
4613 * leaf to its left neighbour, then attempt to
4614 * either push all the remaining items to the
4615 * right neighbour or none. There's no advantage
4616 * in pushing only some items, instead of all, as
4617 * it's pointless to end up with a leaf having
4618 * too few items while the neighbours can be full
4619 * or nearly full.
4620 */
4621 nritems = btrfs_header_nritems(leaf);
4622 min_push_space = leaf_space_used(leaf, 0, nritems);
4623 wret = push_leaf_right(trans, root, path, 0,
4624 min_push_space, 1, 0);
4625 if (wret < 0 && wret != -ENOSPC)
4626 ret = wret;
4627 }
4628
4629 if (btrfs_header_nritems(leaf) == 0) {
4630 path->slots[1] = slot;
4631 ret = btrfs_del_leaf(trans, root, path, leaf);
4632 if (ret < 0)
4633 return ret;
4634 free_extent_buffer(leaf);
4635 ret = 0;
4636 } else {
4637 /* if we're still in the path, make sure
4638 * we're dirty. Otherwise, one of the
4639 * push_leaf functions must have already
4640 * dirtied this buffer
4641 */
4642 if (path->nodes[0] == leaf)
4643 btrfs_mark_buffer_dirty(trans, leaf);
4644 free_extent_buffer(leaf);
4645 }
4646 } else {
4647 btrfs_mark_buffer_dirty(trans, leaf);
4648 }
4649 }
4650 return ret;
4651}
4652
4653/*
4654 * A helper function to walk down the tree starting at min_key, and looking
4655 * for nodes or leaves that are have a minimum transaction id.
4656 * This is used by the btree defrag code, and tree logging
4657 *
4658 * This does not cow, but it does stuff the starting key it finds back
4659 * into min_key, so you can call btrfs_search_slot with cow=1 on the
4660 * key and get a writable path.
4661 *
4662 * This honors path->lowest_level to prevent descent past a given level
4663 * of the tree.
4664 *
4665 * min_trans indicates the oldest transaction that you are interested
4666 * in walking through. Any nodes or leaves older than min_trans are
4667 * skipped over (without reading them).
4668 *
4669 * returns zero if something useful was found, < 0 on error and 1 if there
4670 * was nothing in the tree that matched the search criteria.
4671 */
4672int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4673 struct btrfs_path *path,
4674 u64 min_trans)
4675{
4676 struct extent_buffer *cur;
4677 struct btrfs_key found_key;
4678 int slot;
4679 int sret;
4680 u32 nritems;
4681 int level;
4682 int ret = 1;
4683 int keep_locks = path->keep_locks;
4684
4685 ASSERT(!path->nowait);
4686 path->keep_locks = 1;
4687again:
4688 cur = btrfs_read_lock_root_node(root);
4689 level = btrfs_header_level(cur);
4690 WARN_ON(path->nodes[level]);
4691 path->nodes[level] = cur;
4692 path->locks[level] = BTRFS_READ_LOCK;
4693
4694 if (btrfs_header_generation(cur) < min_trans) {
4695 ret = 1;
4696 goto out;
4697 }
4698 while (1) {
4699 nritems = btrfs_header_nritems(cur);
4700 level = btrfs_header_level(cur);
4701 sret = btrfs_bin_search(cur, 0, min_key, &slot);
4702 if (sret < 0) {
4703 ret = sret;
4704 goto out;
4705 }
4706
4707 /* at the lowest level, we're done, setup the path and exit */
4708 if (level == path->lowest_level) {
4709 if (slot >= nritems)
4710 goto find_next_key;
4711 ret = 0;
4712 path->slots[level] = slot;
4713 btrfs_item_key_to_cpu(cur, &found_key, slot);
4714 goto out;
4715 }
4716 if (sret && slot > 0)
4717 slot--;
4718 /*
4719 * check this node pointer against the min_trans parameters.
4720 * If it is too old, skip to the next one.
4721 */
4722 while (slot < nritems) {
4723 u64 gen;
4724
4725 gen = btrfs_node_ptr_generation(cur, slot);
4726 if (gen < min_trans) {
4727 slot++;
4728 continue;
4729 }
4730 break;
4731 }
4732find_next_key:
4733 /*
4734 * we didn't find a candidate key in this node, walk forward
4735 * and find another one
4736 */
4737 if (slot >= nritems) {
4738 path->slots[level] = slot;
4739 sret = btrfs_find_next_key(root, path, min_key, level,
4740 min_trans);
4741 if (sret == 0) {
4742 btrfs_release_path(path);
4743 goto again;
4744 } else {
4745 goto out;
4746 }
4747 }
4748 /* save our key for returning back */
4749 btrfs_node_key_to_cpu(cur, &found_key, slot);
4750 path->slots[level] = slot;
4751 if (level == path->lowest_level) {
4752 ret = 0;
4753 goto out;
4754 }
4755 cur = btrfs_read_node_slot(cur, slot);
4756 if (IS_ERR(cur)) {
4757 ret = PTR_ERR(cur);
4758 goto out;
4759 }
4760
4761 btrfs_tree_read_lock(cur);
4762
4763 path->locks[level - 1] = BTRFS_READ_LOCK;
4764 path->nodes[level - 1] = cur;
4765 unlock_up(path, level, 1, 0, NULL);
4766 }
4767out:
4768 path->keep_locks = keep_locks;
4769 if (ret == 0) {
4770 btrfs_unlock_up_safe(path, path->lowest_level + 1);
4771 memcpy(min_key, &found_key, sizeof(found_key));
4772 }
4773 return ret;
4774}
4775
4776/*
4777 * this is similar to btrfs_next_leaf, but does not try to preserve
4778 * and fixup the path. It looks for and returns the next key in the
4779 * tree based on the current path and the min_trans parameters.
4780 *
4781 * 0 is returned if another key is found, < 0 if there are any errors
4782 * and 1 is returned if there are no higher keys in the tree
4783 *
4784 * path->keep_locks should be set to 1 on the search made before
4785 * calling this function.
4786 */
4787int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4788 struct btrfs_key *key, int level, u64 min_trans)
4789{
4790 int slot;
4791 struct extent_buffer *c;
4792
4793 WARN_ON(!path->keep_locks && !path->skip_locking);
4794 while (level < BTRFS_MAX_LEVEL) {
4795 if (!path->nodes[level])
4796 return 1;
4797
4798 slot = path->slots[level] + 1;
4799 c = path->nodes[level];
4800next:
4801 if (slot >= btrfs_header_nritems(c)) {
4802 int ret;
4803 int orig_lowest;
4804 struct btrfs_key cur_key;
4805 if (level + 1 >= BTRFS_MAX_LEVEL ||
4806 !path->nodes[level + 1])
4807 return 1;
4808
4809 if (path->locks[level + 1] || path->skip_locking) {
4810 level++;
4811 continue;
4812 }
4813
4814 slot = btrfs_header_nritems(c) - 1;
4815 if (level == 0)
4816 btrfs_item_key_to_cpu(c, &cur_key, slot);
4817 else
4818 btrfs_node_key_to_cpu(c, &cur_key, slot);
4819
4820 orig_lowest = path->lowest_level;
4821 btrfs_release_path(path);
4822 path->lowest_level = level;
4823 ret = btrfs_search_slot(NULL, root, &cur_key, path,
4824 0, 0);
4825 path->lowest_level = orig_lowest;
4826 if (ret < 0)
4827 return ret;
4828
4829 c = path->nodes[level];
4830 slot = path->slots[level];
4831 if (ret == 0)
4832 slot++;
4833 goto next;
4834 }
4835
4836 if (level == 0)
4837 btrfs_item_key_to_cpu(c, key, slot);
4838 else {
4839 u64 gen = btrfs_node_ptr_generation(c, slot);
4840
4841 if (gen < min_trans) {
4842 slot++;
4843 goto next;
4844 }
4845 btrfs_node_key_to_cpu(c, key, slot);
4846 }
4847 return 0;
4848 }
4849 return 1;
4850}
4851
4852int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
4853 u64 time_seq)
4854{
4855 int slot;
4856 int level;
4857 struct extent_buffer *c;
4858 struct extent_buffer *next;
4859 struct btrfs_fs_info *fs_info = root->fs_info;
4860 struct btrfs_key key;
4861 bool need_commit_sem = false;
4862 u32 nritems;
4863 int ret;
4864 int i;
4865
4866 /*
4867 * The nowait semantics are used only for write paths, where we don't
4868 * use the tree mod log and sequence numbers.
4869 */
4870 if (time_seq)
4871 ASSERT(!path->nowait);
4872
4873 nritems = btrfs_header_nritems(path->nodes[0]);
4874 if (nritems == 0)
4875 return 1;
4876
4877 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
4878again:
4879 level = 1;
4880 next = NULL;
4881 btrfs_release_path(path);
4882
4883 path->keep_locks = 1;
4884
4885 if (time_seq) {
4886 ret = btrfs_search_old_slot(root, &key, path, time_seq);
4887 } else {
4888 if (path->need_commit_sem) {
4889 path->need_commit_sem = 0;
4890 need_commit_sem = true;
4891 if (path->nowait) {
4892 if (!down_read_trylock(&fs_info->commit_root_sem)) {
4893 ret = -EAGAIN;
4894 goto done;
4895 }
4896 } else {
4897 down_read(&fs_info->commit_root_sem);
4898 }
4899 }
4900 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4901 }
4902 path->keep_locks = 0;
4903
4904 if (ret < 0)
4905 goto done;
4906
4907 nritems = btrfs_header_nritems(path->nodes[0]);
4908 /*
4909 * by releasing the path above we dropped all our locks. A balance
4910 * could have added more items next to the key that used to be
4911 * at the very end of the block. So, check again here and
4912 * advance the path if there are now more items available.
4913 */
4914 if (nritems > 0 && path->slots[0] < nritems - 1) {
4915 if (ret == 0)
4916 path->slots[0]++;
4917 ret = 0;
4918 goto done;
4919 }
4920 /*
4921 * So the above check misses one case:
4922 * - after releasing the path above, someone has removed the item that
4923 * used to be at the very end of the block, and balance between leafs
4924 * gets another one with bigger key.offset to replace it.
4925 *
4926 * This one should be returned as well, or we can get leaf corruption
4927 * later(esp. in __btrfs_drop_extents()).
4928 *
4929 * And a bit more explanation about this check,
4930 * with ret > 0, the key isn't found, the path points to the slot
4931 * where it should be inserted, so the path->slots[0] item must be the
4932 * bigger one.
4933 */
4934 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
4935 ret = 0;
4936 goto done;
4937 }
4938
4939 while (level < BTRFS_MAX_LEVEL) {
4940 if (!path->nodes[level]) {
4941 ret = 1;
4942 goto done;
4943 }
4944
4945 slot = path->slots[level] + 1;
4946 c = path->nodes[level];
4947 if (slot >= btrfs_header_nritems(c)) {
4948 level++;
4949 if (level == BTRFS_MAX_LEVEL) {
4950 ret = 1;
4951 goto done;
4952 }
4953 continue;
4954 }
4955
4956
4957 /*
4958 * Our current level is where we're going to start from, and to
4959 * make sure lockdep doesn't complain we need to drop our locks
4960 * and nodes from 0 to our current level.
4961 */
4962 for (i = 0; i < level; i++) {
4963 if (path->locks[level]) {
4964 btrfs_tree_read_unlock(path->nodes[i]);
4965 path->locks[i] = 0;
4966 }
4967 free_extent_buffer(path->nodes[i]);
4968 path->nodes[i] = NULL;
4969 }
4970
4971 next = c;
4972 ret = read_block_for_search(root, path, &next, slot, &key);
4973 if (ret == -EAGAIN && !path->nowait)
4974 goto again;
4975
4976 if (ret < 0) {
4977 btrfs_release_path(path);
4978 goto done;
4979 }
4980
4981 if (!path->skip_locking) {
4982 ret = btrfs_try_tree_read_lock(next);
4983 if (!ret && path->nowait) {
4984 ret = -EAGAIN;
4985 goto done;
4986 }
4987 if (!ret && time_seq) {
4988 /*
4989 * If we don't get the lock, we may be racing
4990 * with push_leaf_left, holding that lock while
4991 * itself waiting for the leaf we've currently
4992 * locked. To solve this situation, we give up
4993 * on our lock and cycle.
4994 */
4995 free_extent_buffer(next);
4996 btrfs_release_path(path);
4997 cond_resched();
4998 goto again;
4999 }
5000 if (!ret)
5001 btrfs_tree_read_lock(next);
5002 }
5003 break;
5004 }
5005 path->slots[level] = slot;
5006 while (1) {
5007 level--;
5008 path->nodes[level] = next;
5009 path->slots[level] = 0;
5010 if (!path->skip_locking)
5011 path->locks[level] = BTRFS_READ_LOCK;
5012 if (!level)
5013 break;
5014
5015 ret = read_block_for_search(root, path, &next, 0, &key);
5016 if (ret == -EAGAIN && !path->nowait)
5017 goto again;
5018
5019 if (ret < 0) {
5020 btrfs_release_path(path);
5021 goto done;
5022 }
5023
5024 if (!path->skip_locking) {
5025 if (path->nowait) {
5026 if (!btrfs_try_tree_read_lock(next)) {
5027 ret = -EAGAIN;
5028 goto done;
5029 }
5030 } else {
5031 btrfs_tree_read_lock(next);
5032 }
5033 }
5034 }
5035 ret = 0;
5036done:
5037 unlock_up(path, 0, 1, 0, NULL);
5038 if (need_commit_sem) {
5039 int ret2;
5040
5041 path->need_commit_sem = 1;
5042 ret2 = finish_need_commit_sem_search(path);
5043 up_read(&fs_info->commit_root_sem);
5044 if (ret2)
5045 ret = ret2;
5046 }
5047
5048 return ret;
5049}
5050
5051int btrfs_next_old_item(struct btrfs_root *root, struct btrfs_path *path, u64 time_seq)
5052{
5053 path->slots[0]++;
5054 if (path->slots[0] >= btrfs_header_nritems(path->nodes[0]))
5055 return btrfs_next_old_leaf(root, path, time_seq);
5056 return 0;
5057}
5058
5059/*
5060 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5061 * searching until it gets past min_objectid or finds an item of 'type'
5062 *
5063 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5064 */
5065int btrfs_previous_item(struct btrfs_root *root,
5066 struct btrfs_path *path, u64 min_objectid,
5067 int type)
5068{
5069 struct btrfs_key found_key;
5070 struct extent_buffer *leaf;
5071 u32 nritems;
5072 int ret;
5073
5074 while (1) {
5075 if (path->slots[0] == 0) {
5076 ret = btrfs_prev_leaf(root, path);
5077 if (ret != 0)
5078 return ret;
5079 } else {
5080 path->slots[0]--;
5081 }
5082 leaf = path->nodes[0];
5083 nritems = btrfs_header_nritems(leaf);
5084 if (nritems == 0)
5085 return 1;
5086 if (path->slots[0] == nritems)
5087 path->slots[0]--;
5088
5089 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5090 if (found_key.objectid < min_objectid)
5091 break;
5092 if (found_key.type == type)
5093 return 0;
5094 if (found_key.objectid == min_objectid &&
5095 found_key.type < type)
5096 break;
5097 }
5098 return 1;
5099}
5100
5101/*
5102 * search in extent tree to find a previous Metadata/Data extent item with
5103 * min objecitd.
5104 *
5105 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5106 */
5107int btrfs_previous_extent_item(struct btrfs_root *root,
5108 struct btrfs_path *path, u64 min_objectid)
5109{
5110 struct btrfs_key found_key;
5111 struct extent_buffer *leaf;
5112 u32 nritems;
5113 int ret;
5114
5115 while (1) {
5116 if (path->slots[0] == 0) {
5117 ret = btrfs_prev_leaf(root, path);
5118 if (ret != 0)
5119 return ret;
5120 } else {
5121 path->slots[0]--;
5122 }
5123 leaf = path->nodes[0];
5124 nritems = btrfs_header_nritems(leaf);
5125 if (nritems == 0)
5126 return 1;
5127 if (path->slots[0] == nritems)
5128 path->slots[0]--;
5129
5130 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5131 if (found_key.objectid < min_objectid)
5132 break;
5133 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5134 found_key.type == BTRFS_METADATA_ITEM_KEY)
5135 return 0;
5136 if (found_key.objectid == min_objectid &&
5137 found_key.type < BTRFS_EXTENT_ITEM_KEY)
5138 break;
5139 }
5140 return 1;
5141}
5142
5143int __init btrfs_ctree_init(void)
5144{
5145 btrfs_path_cachep = KMEM_CACHE(btrfs_path, 0);
5146 if (!btrfs_path_cachep)
5147 return -ENOMEM;
5148 return 0;
5149}
5150
5151void __cold btrfs_ctree_exit(void)
5152{
5153 kmem_cache_destroy(btrfs_path_cachep);
5154}
1/*
2 * Copyright (C) 2007,2008 Oracle. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19#include <linux/sched.h>
20#include <linux/slab.h>
21#include <linux/rbtree.h>
22#include "ctree.h"
23#include "disk-io.h"
24#include "transaction.h"
25#include "print-tree.h"
26#include "locking.h"
27
28static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
29 *root, struct btrfs_path *path, int level);
30static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
31 *root, struct btrfs_key *ins_key,
32 struct btrfs_path *path, int data_size, int extend);
33static int push_node_left(struct btrfs_trans_handle *trans,
34 struct btrfs_root *root, struct extent_buffer *dst,
35 struct extent_buffer *src, int empty);
36static int balance_node_right(struct btrfs_trans_handle *trans,
37 struct btrfs_root *root,
38 struct extent_buffer *dst_buf,
39 struct extent_buffer *src_buf);
40static void del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
41 struct btrfs_path *path, int level, int slot,
42 int tree_mod_log);
43static void tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
44 struct extent_buffer *eb);
45struct extent_buffer *read_old_tree_block(struct btrfs_root *root, u64 bytenr,
46 u32 blocksize, u64 parent_transid,
47 u64 time_seq);
48struct extent_buffer *btrfs_find_old_tree_block(struct btrfs_root *root,
49 u64 bytenr, u32 blocksize,
50 u64 time_seq);
51
52struct btrfs_path *btrfs_alloc_path(void)
53{
54 struct btrfs_path *path;
55 path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
56 return path;
57}
58
59/*
60 * set all locked nodes in the path to blocking locks. This should
61 * be done before scheduling
62 */
63noinline void btrfs_set_path_blocking(struct btrfs_path *p)
64{
65 int i;
66 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
67 if (!p->nodes[i] || !p->locks[i])
68 continue;
69 btrfs_set_lock_blocking_rw(p->nodes[i], p->locks[i]);
70 if (p->locks[i] == BTRFS_READ_LOCK)
71 p->locks[i] = BTRFS_READ_LOCK_BLOCKING;
72 else if (p->locks[i] == BTRFS_WRITE_LOCK)
73 p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING;
74 }
75}
76
77/*
78 * reset all the locked nodes in the patch to spinning locks.
79 *
80 * held is used to keep lockdep happy, when lockdep is enabled
81 * we set held to a blocking lock before we go around and
82 * retake all the spinlocks in the path. You can safely use NULL
83 * for held
84 */
85noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
86 struct extent_buffer *held, int held_rw)
87{
88 int i;
89
90#ifdef CONFIG_DEBUG_LOCK_ALLOC
91 /* lockdep really cares that we take all of these spinlocks
92 * in the right order. If any of the locks in the path are not
93 * currently blocking, it is going to complain. So, make really
94 * really sure by forcing the path to blocking before we clear
95 * the path blocking.
96 */
97 if (held) {
98 btrfs_set_lock_blocking_rw(held, held_rw);
99 if (held_rw == BTRFS_WRITE_LOCK)
100 held_rw = BTRFS_WRITE_LOCK_BLOCKING;
101 else if (held_rw == BTRFS_READ_LOCK)
102 held_rw = BTRFS_READ_LOCK_BLOCKING;
103 }
104 btrfs_set_path_blocking(p);
105#endif
106
107 for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
108 if (p->nodes[i] && p->locks[i]) {
109 btrfs_clear_lock_blocking_rw(p->nodes[i], p->locks[i]);
110 if (p->locks[i] == BTRFS_WRITE_LOCK_BLOCKING)
111 p->locks[i] = BTRFS_WRITE_LOCK;
112 else if (p->locks[i] == BTRFS_READ_LOCK_BLOCKING)
113 p->locks[i] = BTRFS_READ_LOCK;
114 }
115 }
116
117#ifdef CONFIG_DEBUG_LOCK_ALLOC
118 if (held)
119 btrfs_clear_lock_blocking_rw(held, held_rw);
120#endif
121}
122
123/* this also releases the path */
124void btrfs_free_path(struct btrfs_path *p)
125{
126 if (!p)
127 return;
128 btrfs_release_path(p);
129 kmem_cache_free(btrfs_path_cachep, p);
130}
131
132/*
133 * path release drops references on the extent buffers in the path
134 * and it drops any locks held by this path
135 *
136 * It is safe to call this on paths that no locks or extent buffers held.
137 */
138noinline void btrfs_release_path(struct btrfs_path *p)
139{
140 int i;
141
142 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
143 p->slots[i] = 0;
144 if (!p->nodes[i])
145 continue;
146 if (p->locks[i]) {
147 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
148 p->locks[i] = 0;
149 }
150 free_extent_buffer(p->nodes[i]);
151 p->nodes[i] = NULL;
152 }
153}
154
155/*
156 * safely gets a reference on the root node of a tree. A lock
157 * is not taken, so a concurrent writer may put a different node
158 * at the root of the tree. See btrfs_lock_root_node for the
159 * looping required.
160 *
161 * The extent buffer returned by this has a reference taken, so
162 * it won't disappear. It may stop being the root of the tree
163 * at any time because there are no locks held.
164 */
165struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
166{
167 struct extent_buffer *eb;
168
169 while (1) {
170 rcu_read_lock();
171 eb = rcu_dereference(root->node);
172
173 /*
174 * RCU really hurts here, we could free up the root node because
175 * it was cow'ed but we may not get the new root node yet so do
176 * the inc_not_zero dance and if it doesn't work then
177 * synchronize_rcu and try again.
178 */
179 if (atomic_inc_not_zero(&eb->refs)) {
180 rcu_read_unlock();
181 break;
182 }
183 rcu_read_unlock();
184 synchronize_rcu();
185 }
186 return eb;
187}
188
189/* loop around taking references on and locking the root node of the
190 * tree until you end up with a lock on the root. A locked buffer
191 * is returned, with a reference held.
192 */
193struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
194{
195 struct extent_buffer *eb;
196
197 while (1) {
198 eb = btrfs_root_node(root);
199 btrfs_tree_lock(eb);
200 if (eb == root->node)
201 break;
202 btrfs_tree_unlock(eb);
203 free_extent_buffer(eb);
204 }
205 return eb;
206}
207
208/* loop around taking references on and locking the root node of the
209 * tree until you end up with a lock on the root. A locked buffer
210 * is returned, with a reference held.
211 */
212struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
213{
214 struct extent_buffer *eb;
215
216 while (1) {
217 eb = btrfs_root_node(root);
218 btrfs_tree_read_lock(eb);
219 if (eb == root->node)
220 break;
221 btrfs_tree_read_unlock(eb);
222 free_extent_buffer(eb);
223 }
224 return eb;
225}
226
227/* cowonly root (everything not a reference counted cow subvolume), just get
228 * put onto a simple dirty list. transaction.c walks this to make sure they
229 * get properly updated on disk.
230 */
231static void add_root_to_dirty_list(struct btrfs_root *root)
232{
233 spin_lock(&root->fs_info->trans_lock);
234 if (root->track_dirty && list_empty(&root->dirty_list)) {
235 list_add(&root->dirty_list,
236 &root->fs_info->dirty_cowonly_roots);
237 }
238 spin_unlock(&root->fs_info->trans_lock);
239}
240
241/*
242 * used by snapshot creation to make a copy of a root for a tree with
243 * a given objectid. The buffer with the new root node is returned in
244 * cow_ret, and this func returns zero on success or a negative error code.
245 */
246int btrfs_copy_root(struct btrfs_trans_handle *trans,
247 struct btrfs_root *root,
248 struct extent_buffer *buf,
249 struct extent_buffer **cow_ret, u64 new_root_objectid)
250{
251 struct extent_buffer *cow;
252 int ret = 0;
253 int level;
254 struct btrfs_disk_key disk_key;
255
256 WARN_ON(root->ref_cows && trans->transid !=
257 root->fs_info->running_transaction->transid);
258 WARN_ON(root->ref_cows && trans->transid != root->last_trans);
259
260 level = btrfs_header_level(buf);
261 if (level == 0)
262 btrfs_item_key(buf, &disk_key, 0);
263 else
264 btrfs_node_key(buf, &disk_key, 0);
265
266 cow = btrfs_alloc_free_block(trans, root, buf->len, 0,
267 new_root_objectid, &disk_key, level,
268 buf->start, 0);
269 if (IS_ERR(cow))
270 return PTR_ERR(cow);
271
272 copy_extent_buffer(cow, buf, 0, 0, cow->len);
273 btrfs_set_header_bytenr(cow, cow->start);
274 btrfs_set_header_generation(cow, trans->transid);
275 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
276 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
277 BTRFS_HEADER_FLAG_RELOC);
278 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
279 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
280 else
281 btrfs_set_header_owner(cow, new_root_objectid);
282
283 write_extent_buffer(cow, root->fs_info->fsid,
284 (unsigned long)btrfs_header_fsid(cow),
285 BTRFS_FSID_SIZE);
286
287 WARN_ON(btrfs_header_generation(buf) > trans->transid);
288 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
289 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
290 else
291 ret = btrfs_inc_ref(trans, root, cow, 0, 1);
292
293 if (ret)
294 return ret;
295
296 btrfs_mark_buffer_dirty(cow);
297 *cow_ret = cow;
298 return 0;
299}
300
301enum mod_log_op {
302 MOD_LOG_KEY_REPLACE,
303 MOD_LOG_KEY_ADD,
304 MOD_LOG_KEY_REMOVE,
305 MOD_LOG_KEY_REMOVE_WHILE_FREEING,
306 MOD_LOG_KEY_REMOVE_WHILE_MOVING,
307 MOD_LOG_MOVE_KEYS,
308 MOD_LOG_ROOT_REPLACE,
309};
310
311struct tree_mod_move {
312 int dst_slot;
313 int nr_items;
314};
315
316struct tree_mod_root {
317 u64 logical;
318 u8 level;
319};
320
321struct tree_mod_elem {
322 struct rb_node node;
323 u64 index; /* shifted logical */
324 struct seq_list elem;
325 enum mod_log_op op;
326
327 /* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
328 int slot;
329
330 /* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
331 u64 generation;
332
333 /* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
334 struct btrfs_disk_key key;
335 u64 blockptr;
336
337 /* this is used for op == MOD_LOG_MOVE_KEYS */
338 struct tree_mod_move move;
339
340 /* this is used for op == MOD_LOG_ROOT_REPLACE */
341 struct tree_mod_root old_root;
342};
343
344static inline void
345__get_tree_mod_seq(struct btrfs_fs_info *fs_info, struct seq_list *elem)
346{
347 elem->seq = atomic_inc_return(&fs_info->tree_mod_seq);
348 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
349}
350
351void btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
352 struct seq_list *elem)
353{
354 elem->flags = 1;
355 spin_lock(&fs_info->tree_mod_seq_lock);
356 __get_tree_mod_seq(fs_info, elem);
357 spin_unlock(&fs_info->tree_mod_seq_lock);
358}
359
360void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
361 struct seq_list *elem)
362{
363 struct rb_root *tm_root;
364 struct rb_node *node;
365 struct rb_node *next;
366 struct seq_list *cur_elem;
367 struct tree_mod_elem *tm;
368 u64 min_seq = (u64)-1;
369 u64 seq_putting = elem->seq;
370
371 if (!seq_putting)
372 return;
373
374 BUG_ON(!(elem->flags & 1));
375 spin_lock(&fs_info->tree_mod_seq_lock);
376 list_del(&elem->list);
377
378 list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) {
379 if ((cur_elem->flags & 1) && cur_elem->seq < min_seq) {
380 if (seq_putting > cur_elem->seq) {
381 /*
382 * blocker with lower sequence number exists, we
383 * cannot remove anything from the log
384 */
385 goto out;
386 }
387 min_seq = cur_elem->seq;
388 }
389 }
390
391 /*
392 * anything that's lower than the lowest existing (read: blocked)
393 * sequence number can be removed from the tree.
394 */
395 write_lock(&fs_info->tree_mod_log_lock);
396 tm_root = &fs_info->tree_mod_log;
397 for (node = rb_first(tm_root); node; node = next) {
398 next = rb_next(node);
399 tm = container_of(node, struct tree_mod_elem, node);
400 if (tm->elem.seq > min_seq)
401 continue;
402 rb_erase(node, tm_root);
403 list_del(&tm->elem.list);
404 kfree(tm);
405 }
406 write_unlock(&fs_info->tree_mod_log_lock);
407out:
408 spin_unlock(&fs_info->tree_mod_seq_lock);
409}
410
411/*
412 * key order of the log:
413 * index -> sequence
414 *
415 * the index is the shifted logical of the *new* root node for root replace
416 * operations, or the shifted logical of the affected block for all other
417 * operations.
418 */
419static noinline int
420__tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
421{
422 struct rb_root *tm_root;
423 struct rb_node **new;
424 struct rb_node *parent = NULL;
425 struct tree_mod_elem *cur;
426 int ret = 0;
427
428 BUG_ON(!tm || !tm->elem.seq);
429
430 write_lock(&fs_info->tree_mod_log_lock);
431 tm_root = &fs_info->tree_mod_log;
432 new = &tm_root->rb_node;
433 while (*new) {
434 cur = container_of(*new, struct tree_mod_elem, node);
435 parent = *new;
436 if (cur->index < tm->index)
437 new = &((*new)->rb_left);
438 else if (cur->index > tm->index)
439 new = &((*new)->rb_right);
440 else if (cur->elem.seq < tm->elem.seq)
441 new = &((*new)->rb_left);
442 else if (cur->elem.seq > tm->elem.seq)
443 new = &((*new)->rb_right);
444 else {
445 kfree(tm);
446 ret = -EEXIST;
447 goto unlock;
448 }
449 }
450
451 rb_link_node(&tm->node, parent, new);
452 rb_insert_color(&tm->node, tm_root);
453unlock:
454 write_unlock(&fs_info->tree_mod_log_lock);
455 return ret;
456}
457
458static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
459 struct extent_buffer *eb) {
460 smp_mb();
461 if (list_empty(&(fs_info)->tree_mod_seq_list))
462 return 1;
463 if (!eb)
464 return 0;
465 if (btrfs_header_level(eb) == 0)
466 return 1;
467 return 0;
468}
469
470/*
471 * This allocates memory and gets a tree modification sequence number when
472 * needed.
473 *
474 * Returns 0 when no sequence number is needed, < 0 on error.
475 * Returns 1 when a sequence number was added. In this case,
476 * fs_info->tree_mod_seq_lock was acquired and must be released by the caller
477 * after inserting into the rb tree.
478 */
479static inline int tree_mod_alloc(struct btrfs_fs_info *fs_info, gfp_t flags,
480 struct tree_mod_elem **tm_ret)
481{
482 struct tree_mod_elem *tm;
483 int seq;
484
485 if (tree_mod_dont_log(fs_info, NULL))
486 return 0;
487
488 tm = *tm_ret = kzalloc(sizeof(*tm), flags);
489 if (!tm)
490 return -ENOMEM;
491
492 tm->elem.flags = 0;
493 spin_lock(&fs_info->tree_mod_seq_lock);
494 if (list_empty(&fs_info->tree_mod_seq_list)) {
495 /*
496 * someone emptied the list while we were waiting for the lock.
497 * we must not add to the list, because no blocker exists. items
498 * are removed from the list only when the existing blocker is
499 * removed from the list.
500 */
501 kfree(tm);
502 seq = 0;
503 spin_unlock(&fs_info->tree_mod_seq_lock);
504 } else {
505 __get_tree_mod_seq(fs_info, &tm->elem);
506 seq = tm->elem.seq;
507 }
508
509 return seq;
510}
511
512static noinline int
513tree_mod_log_insert_key_mask(struct btrfs_fs_info *fs_info,
514 struct extent_buffer *eb, int slot,
515 enum mod_log_op op, gfp_t flags)
516{
517 struct tree_mod_elem *tm;
518 int ret;
519
520 ret = tree_mod_alloc(fs_info, flags, &tm);
521 if (ret <= 0)
522 return ret;
523
524 tm->index = eb->start >> PAGE_CACHE_SHIFT;
525 if (op != MOD_LOG_KEY_ADD) {
526 btrfs_node_key(eb, &tm->key, slot);
527 tm->blockptr = btrfs_node_blockptr(eb, slot);
528 }
529 tm->op = op;
530 tm->slot = slot;
531 tm->generation = btrfs_node_ptr_generation(eb, slot);
532
533 ret = __tree_mod_log_insert(fs_info, tm);
534 spin_unlock(&fs_info->tree_mod_seq_lock);
535 return ret;
536}
537
538static noinline int
539tree_mod_log_insert_key(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
540 int slot, enum mod_log_op op)
541{
542 return tree_mod_log_insert_key_mask(fs_info, eb, slot, op, GFP_NOFS);
543}
544
545static noinline int
546tree_mod_log_insert_move(struct btrfs_fs_info *fs_info,
547 struct extent_buffer *eb, int dst_slot, int src_slot,
548 int nr_items, gfp_t flags)
549{
550 struct tree_mod_elem *tm;
551 int ret;
552 int i;
553
554 if (tree_mod_dont_log(fs_info, eb))
555 return 0;
556
557 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
558 ret = tree_mod_log_insert_key(fs_info, eb, i + dst_slot,
559 MOD_LOG_KEY_REMOVE_WHILE_MOVING);
560 BUG_ON(ret < 0);
561 }
562
563 ret = tree_mod_alloc(fs_info, flags, &tm);
564 if (ret <= 0)
565 return ret;
566
567 tm->index = eb->start >> PAGE_CACHE_SHIFT;
568 tm->slot = src_slot;
569 tm->move.dst_slot = dst_slot;
570 tm->move.nr_items = nr_items;
571 tm->op = MOD_LOG_MOVE_KEYS;
572
573 ret = __tree_mod_log_insert(fs_info, tm);
574 spin_unlock(&fs_info->tree_mod_seq_lock);
575 return ret;
576}
577
578static noinline int
579tree_mod_log_insert_root(struct btrfs_fs_info *fs_info,
580 struct extent_buffer *old_root,
581 struct extent_buffer *new_root, gfp_t flags)
582{
583 struct tree_mod_elem *tm;
584 int ret;
585
586 ret = tree_mod_alloc(fs_info, flags, &tm);
587 if (ret <= 0)
588 return ret;
589
590 tm->index = new_root->start >> PAGE_CACHE_SHIFT;
591 tm->old_root.logical = old_root->start;
592 tm->old_root.level = btrfs_header_level(old_root);
593 tm->generation = btrfs_header_generation(old_root);
594 tm->op = MOD_LOG_ROOT_REPLACE;
595
596 ret = __tree_mod_log_insert(fs_info, tm);
597 spin_unlock(&fs_info->tree_mod_seq_lock);
598 return ret;
599}
600
601static struct tree_mod_elem *
602__tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
603 int smallest)
604{
605 struct rb_root *tm_root;
606 struct rb_node *node;
607 struct tree_mod_elem *cur = NULL;
608 struct tree_mod_elem *found = NULL;
609 u64 index = start >> PAGE_CACHE_SHIFT;
610
611 read_lock(&fs_info->tree_mod_log_lock);
612 tm_root = &fs_info->tree_mod_log;
613 node = tm_root->rb_node;
614 while (node) {
615 cur = container_of(node, struct tree_mod_elem, node);
616 if (cur->index < index) {
617 node = node->rb_left;
618 } else if (cur->index > index) {
619 node = node->rb_right;
620 } else if (cur->elem.seq < min_seq) {
621 node = node->rb_left;
622 } else if (!smallest) {
623 /* we want the node with the highest seq */
624 if (found)
625 BUG_ON(found->elem.seq > cur->elem.seq);
626 found = cur;
627 node = node->rb_left;
628 } else if (cur->elem.seq > min_seq) {
629 /* we want the node with the smallest seq */
630 if (found)
631 BUG_ON(found->elem.seq < cur->elem.seq);
632 found = cur;
633 node = node->rb_right;
634 } else {
635 found = cur;
636 break;
637 }
638 }
639 read_unlock(&fs_info->tree_mod_log_lock);
640
641 return found;
642}
643
644/*
645 * this returns the element from the log with the smallest time sequence
646 * value that's in the log (the oldest log item). any element with a time
647 * sequence lower than min_seq will be ignored.
648 */
649static struct tree_mod_elem *
650tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
651 u64 min_seq)
652{
653 return __tree_mod_log_search(fs_info, start, min_seq, 1);
654}
655
656/*
657 * this returns the element from the log with the largest time sequence
658 * value that's in the log (the most recent log item). any element with
659 * a time sequence lower than min_seq will be ignored.
660 */
661static struct tree_mod_elem *
662tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
663{
664 return __tree_mod_log_search(fs_info, start, min_seq, 0);
665}
666
667static inline void
668tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
669 struct extent_buffer *src, unsigned long dst_offset,
670 unsigned long src_offset, int nr_items)
671{
672 int ret;
673 int i;
674
675 if (tree_mod_dont_log(fs_info, NULL))
676 return;
677
678 if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
679 return;
680
681 /* speed this up by single seq for all operations? */
682 for (i = 0; i < nr_items; i++) {
683 ret = tree_mod_log_insert_key(fs_info, src, i + src_offset,
684 MOD_LOG_KEY_REMOVE);
685 BUG_ON(ret < 0);
686 ret = tree_mod_log_insert_key(fs_info, dst, i + dst_offset,
687 MOD_LOG_KEY_ADD);
688 BUG_ON(ret < 0);
689 }
690}
691
692static inline void
693tree_mod_log_eb_move(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
694 int dst_offset, int src_offset, int nr_items)
695{
696 int ret;
697 ret = tree_mod_log_insert_move(fs_info, dst, dst_offset, src_offset,
698 nr_items, GFP_NOFS);
699 BUG_ON(ret < 0);
700}
701
702static inline void
703tree_mod_log_set_node_key(struct btrfs_fs_info *fs_info,
704 struct extent_buffer *eb,
705 struct btrfs_disk_key *disk_key, int slot, int atomic)
706{
707 int ret;
708
709 ret = tree_mod_log_insert_key_mask(fs_info, eb, slot,
710 MOD_LOG_KEY_REPLACE,
711 atomic ? GFP_ATOMIC : GFP_NOFS);
712 BUG_ON(ret < 0);
713}
714
715static void tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
716 struct extent_buffer *eb)
717{
718 int i;
719 int ret;
720 u32 nritems;
721
722 if (tree_mod_dont_log(fs_info, eb))
723 return;
724
725 nritems = btrfs_header_nritems(eb);
726 for (i = nritems - 1; i >= 0; i--) {
727 ret = tree_mod_log_insert_key(fs_info, eb, i,
728 MOD_LOG_KEY_REMOVE_WHILE_FREEING);
729 BUG_ON(ret < 0);
730 }
731}
732
733static inline void
734tree_mod_log_set_root_pointer(struct btrfs_root *root,
735 struct extent_buffer *new_root_node)
736{
737 int ret;
738 tree_mod_log_free_eb(root->fs_info, root->node);
739 ret = tree_mod_log_insert_root(root->fs_info, root->node,
740 new_root_node, GFP_NOFS);
741 BUG_ON(ret < 0);
742}
743
744/*
745 * check if the tree block can be shared by multiple trees
746 */
747int btrfs_block_can_be_shared(struct btrfs_root *root,
748 struct extent_buffer *buf)
749{
750 /*
751 * Tree blocks not in refernece counted trees and tree roots
752 * are never shared. If a block was allocated after the last
753 * snapshot and the block was not allocated by tree relocation,
754 * we know the block is not shared.
755 */
756 if (root->ref_cows &&
757 buf != root->node && buf != root->commit_root &&
758 (btrfs_header_generation(buf) <=
759 btrfs_root_last_snapshot(&root->root_item) ||
760 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
761 return 1;
762#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
763 if (root->ref_cows &&
764 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
765 return 1;
766#endif
767 return 0;
768}
769
770static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
771 struct btrfs_root *root,
772 struct extent_buffer *buf,
773 struct extent_buffer *cow,
774 int *last_ref)
775{
776 u64 refs;
777 u64 owner;
778 u64 flags;
779 u64 new_flags = 0;
780 int ret;
781
782 /*
783 * Backrefs update rules:
784 *
785 * Always use full backrefs for extent pointers in tree block
786 * allocated by tree relocation.
787 *
788 * If a shared tree block is no longer referenced by its owner
789 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
790 * use full backrefs for extent pointers in tree block.
791 *
792 * If a tree block is been relocating
793 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
794 * use full backrefs for extent pointers in tree block.
795 * The reason for this is some operations (such as drop tree)
796 * are only allowed for blocks use full backrefs.
797 */
798
799 if (btrfs_block_can_be_shared(root, buf)) {
800 ret = btrfs_lookup_extent_info(trans, root, buf->start,
801 buf->len, &refs, &flags);
802 if (ret)
803 return ret;
804 if (refs == 0) {
805 ret = -EROFS;
806 btrfs_std_error(root->fs_info, ret);
807 return ret;
808 }
809 } else {
810 refs = 1;
811 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
812 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
813 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
814 else
815 flags = 0;
816 }
817
818 owner = btrfs_header_owner(buf);
819 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
820 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
821
822 if (refs > 1) {
823 if ((owner == root->root_key.objectid ||
824 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
825 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
826 ret = btrfs_inc_ref(trans, root, buf, 1, 1);
827 BUG_ON(ret); /* -ENOMEM */
828
829 if (root->root_key.objectid ==
830 BTRFS_TREE_RELOC_OBJECTID) {
831 ret = btrfs_dec_ref(trans, root, buf, 0, 1);
832 BUG_ON(ret); /* -ENOMEM */
833 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
834 BUG_ON(ret); /* -ENOMEM */
835 }
836 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
837 } else {
838
839 if (root->root_key.objectid ==
840 BTRFS_TREE_RELOC_OBJECTID)
841 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
842 else
843 ret = btrfs_inc_ref(trans, root, cow, 0, 1);
844 BUG_ON(ret); /* -ENOMEM */
845 }
846 if (new_flags != 0) {
847 ret = btrfs_set_disk_extent_flags(trans, root,
848 buf->start,
849 buf->len,
850 new_flags, 0);
851 if (ret)
852 return ret;
853 }
854 } else {
855 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
856 if (root->root_key.objectid ==
857 BTRFS_TREE_RELOC_OBJECTID)
858 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
859 else
860 ret = btrfs_inc_ref(trans, root, cow, 0, 1);
861 BUG_ON(ret); /* -ENOMEM */
862 ret = btrfs_dec_ref(trans, root, buf, 1, 1);
863 BUG_ON(ret); /* -ENOMEM */
864 }
865 /*
866 * don't log freeing in case we're freeing the root node, this
867 * is done by tree_mod_log_set_root_pointer later
868 */
869 if (buf != root->node && btrfs_header_level(buf) != 0)
870 tree_mod_log_free_eb(root->fs_info, buf);
871 clean_tree_block(trans, root, buf);
872 *last_ref = 1;
873 }
874 return 0;
875}
876
877/*
878 * does the dirty work in cow of a single block. The parent block (if
879 * supplied) is updated to point to the new cow copy. The new buffer is marked
880 * dirty and returned locked. If you modify the block it needs to be marked
881 * dirty again.
882 *
883 * search_start -- an allocation hint for the new block
884 *
885 * empty_size -- a hint that you plan on doing more cow. This is the size in
886 * bytes the allocator should try to find free next to the block it returns.
887 * This is just a hint and may be ignored by the allocator.
888 */
889static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
890 struct btrfs_root *root,
891 struct extent_buffer *buf,
892 struct extent_buffer *parent, int parent_slot,
893 struct extent_buffer **cow_ret,
894 u64 search_start, u64 empty_size)
895{
896 struct btrfs_disk_key disk_key;
897 struct extent_buffer *cow;
898 int level, ret;
899 int last_ref = 0;
900 int unlock_orig = 0;
901 u64 parent_start;
902
903 if (*cow_ret == buf)
904 unlock_orig = 1;
905
906 btrfs_assert_tree_locked(buf);
907
908 WARN_ON(root->ref_cows && trans->transid !=
909 root->fs_info->running_transaction->transid);
910 WARN_ON(root->ref_cows && trans->transid != root->last_trans);
911
912 level = btrfs_header_level(buf);
913
914 if (level == 0)
915 btrfs_item_key(buf, &disk_key, 0);
916 else
917 btrfs_node_key(buf, &disk_key, 0);
918
919 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
920 if (parent)
921 parent_start = parent->start;
922 else
923 parent_start = 0;
924 } else
925 parent_start = 0;
926
927 cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start,
928 root->root_key.objectid, &disk_key,
929 level, search_start, empty_size);
930 if (IS_ERR(cow))
931 return PTR_ERR(cow);
932
933 /* cow is set to blocking by btrfs_init_new_buffer */
934
935 copy_extent_buffer(cow, buf, 0, 0, cow->len);
936 btrfs_set_header_bytenr(cow, cow->start);
937 btrfs_set_header_generation(cow, trans->transid);
938 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
939 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
940 BTRFS_HEADER_FLAG_RELOC);
941 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
942 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
943 else
944 btrfs_set_header_owner(cow, root->root_key.objectid);
945
946 write_extent_buffer(cow, root->fs_info->fsid,
947 (unsigned long)btrfs_header_fsid(cow),
948 BTRFS_FSID_SIZE);
949
950 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
951 if (ret) {
952 btrfs_abort_transaction(trans, root, ret);
953 return ret;
954 }
955
956 if (root->ref_cows)
957 btrfs_reloc_cow_block(trans, root, buf, cow);
958
959 if (buf == root->node) {
960 WARN_ON(parent && parent != buf);
961 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
962 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
963 parent_start = buf->start;
964 else
965 parent_start = 0;
966
967 extent_buffer_get(cow);
968 tree_mod_log_set_root_pointer(root, cow);
969 rcu_assign_pointer(root->node, cow);
970
971 btrfs_free_tree_block(trans, root, buf, parent_start,
972 last_ref);
973 free_extent_buffer(buf);
974 add_root_to_dirty_list(root);
975 } else {
976 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
977 parent_start = parent->start;
978 else
979 parent_start = 0;
980
981 WARN_ON(trans->transid != btrfs_header_generation(parent));
982 tree_mod_log_insert_key(root->fs_info, parent, parent_slot,
983 MOD_LOG_KEY_REPLACE);
984 btrfs_set_node_blockptr(parent, parent_slot,
985 cow->start);
986 btrfs_set_node_ptr_generation(parent, parent_slot,
987 trans->transid);
988 btrfs_mark_buffer_dirty(parent);
989 btrfs_free_tree_block(trans, root, buf, parent_start,
990 last_ref);
991 }
992 if (unlock_orig)
993 btrfs_tree_unlock(buf);
994 free_extent_buffer_stale(buf);
995 btrfs_mark_buffer_dirty(cow);
996 *cow_ret = cow;
997 return 0;
998}
999
1000/*
1001 * returns the logical address of the oldest predecessor of the given root.
1002 * entries older than time_seq are ignored.
1003 */
1004static struct tree_mod_elem *
1005__tree_mod_log_oldest_root(struct btrfs_fs_info *fs_info,
1006 struct btrfs_root *root, u64 time_seq)
1007{
1008 struct tree_mod_elem *tm;
1009 struct tree_mod_elem *found = NULL;
1010 u64 root_logical = root->node->start;
1011 int looped = 0;
1012
1013 if (!time_seq)
1014 return 0;
1015
1016 /*
1017 * the very last operation that's logged for a root is the replacement
1018 * operation (if it is replaced at all). this has the index of the *new*
1019 * root, making it the very first operation that's logged for this root.
1020 */
1021 while (1) {
1022 tm = tree_mod_log_search_oldest(fs_info, root_logical,
1023 time_seq);
1024 if (!looped && !tm)
1025 return 0;
1026 /*
1027 * if there are no tree operation for the oldest root, we simply
1028 * return it. this should only happen if that (old) root is at
1029 * level 0.
1030 */
1031 if (!tm)
1032 break;
1033
1034 /*
1035 * if there's an operation that's not a root replacement, we
1036 * found the oldest version of our root. normally, we'll find a
1037 * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1038 */
1039 if (tm->op != MOD_LOG_ROOT_REPLACE)
1040 break;
1041
1042 found = tm;
1043 root_logical = tm->old_root.logical;
1044 BUG_ON(root_logical == root->node->start);
1045 looped = 1;
1046 }
1047
1048 /* if there's no old root to return, return what we found instead */
1049 if (!found)
1050 found = tm;
1051
1052 return found;
1053}
1054
1055/*
1056 * tm is a pointer to the first operation to rewind within eb. then, all
1057 * previous operations will be rewinded (until we reach something older than
1058 * time_seq).
1059 */
1060static void
1061__tree_mod_log_rewind(struct extent_buffer *eb, u64 time_seq,
1062 struct tree_mod_elem *first_tm)
1063{
1064 u32 n;
1065 struct rb_node *next;
1066 struct tree_mod_elem *tm = first_tm;
1067 unsigned long o_dst;
1068 unsigned long o_src;
1069 unsigned long p_size = sizeof(struct btrfs_key_ptr);
1070
1071 n = btrfs_header_nritems(eb);
1072 while (tm && tm->elem.seq >= time_seq) {
1073 /*
1074 * all the operations are recorded with the operator used for
1075 * the modification. as we're going backwards, we do the
1076 * opposite of each operation here.
1077 */
1078 switch (tm->op) {
1079 case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1080 BUG_ON(tm->slot < n);
1081 case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1082 case MOD_LOG_KEY_REMOVE:
1083 btrfs_set_node_key(eb, &tm->key, tm->slot);
1084 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1085 btrfs_set_node_ptr_generation(eb, tm->slot,
1086 tm->generation);
1087 n++;
1088 break;
1089 case MOD_LOG_KEY_REPLACE:
1090 BUG_ON(tm->slot >= n);
1091 btrfs_set_node_key(eb, &tm->key, tm->slot);
1092 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1093 btrfs_set_node_ptr_generation(eb, tm->slot,
1094 tm->generation);
1095 break;
1096 case MOD_LOG_KEY_ADD:
1097 /* if a move operation is needed it's in the log */
1098 n--;
1099 break;
1100 case MOD_LOG_MOVE_KEYS:
1101 o_dst = btrfs_node_key_ptr_offset(tm->slot);
1102 o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1103 memmove_extent_buffer(eb, o_dst, o_src,
1104 tm->move.nr_items * p_size);
1105 break;
1106 case MOD_LOG_ROOT_REPLACE:
1107 /*
1108 * this operation is special. for roots, this must be
1109 * handled explicitly before rewinding.
1110 * for non-roots, this operation may exist if the node
1111 * was a root: root A -> child B; then A gets empty and
1112 * B is promoted to the new root. in the mod log, we'll
1113 * have a root-replace operation for B, a tree block
1114 * that is no root. we simply ignore that operation.
1115 */
1116 break;
1117 }
1118 next = rb_next(&tm->node);
1119 if (!next)
1120 break;
1121 tm = container_of(next, struct tree_mod_elem, node);
1122 if (tm->index != first_tm->index)
1123 break;
1124 }
1125 btrfs_set_header_nritems(eb, n);
1126}
1127
1128static struct extent_buffer *
1129tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1130 u64 time_seq)
1131{
1132 struct extent_buffer *eb_rewin;
1133 struct tree_mod_elem *tm;
1134
1135 if (!time_seq)
1136 return eb;
1137
1138 if (btrfs_header_level(eb) == 0)
1139 return eb;
1140
1141 tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1142 if (!tm)
1143 return eb;
1144
1145 if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1146 BUG_ON(tm->slot != 0);
1147 eb_rewin = alloc_dummy_extent_buffer(eb->start,
1148 fs_info->tree_root->nodesize);
1149 BUG_ON(!eb_rewin);
1150 btrfs_set_header_bytenr(eb_rewin, eb->start);
1151 btrfs_set_header_backref_rev(eb_rewin,
1152 btrfs_header_backref_rev(eb));
1153 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1154 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1155 } else {
1156 eb_rewin = btrfs_clone_extent_buffer(eb);
1157 BUG_ON(!eb_rewin);
1158 }
1159
1160 extent_buffer_get(eb_rewin);
1161 free_extent_buffer(eb);
1162
1163 __tree_mod_log_rewind(eb_rewin, time_seq, tm);
1164
1165 return eb_rewin;
1166}
1167
1168/*
1169 * get_old_root() rewinds the state of @root's root node to the given @time_seq
1170 * value. If there are no changes, the current root->root_node is returned. If
1171 * anything changed in between, there's a fresh buffer allocated on which the
1172 * rewind operations are done. In any case, the returned buffer is read locked.
1173 * Returns NULL on error (with no locks held).
1174 */
1175static inline struct extent_buffer *
1176get_old_root(struct btrfs_root *root, u64 time_seq)
1177{
1178 struct tree_mod_elem *tm;
1179 struct extent_buffer *eb;
1180 struct tree_mod_root *old_root = NULL;
1181 u64 old_generation = 0;
1182 u64 logical;
1183
1184 eb = btrfs_read_lock_root_node(root);
1185 tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
1186 if (!tm)
1187 return root->node;
1188
1189 if (tm->op == MOD_LOG_ROOT_REPLACE) {
1190 old_root = &tm->old_root;
1191 old_generation = tm->generation;
1192 logical = old_root->logical;
1193 } else {
1194 logical = root->node->start;
1195 }
1196
1197 tm = tree_mod_log_search(root->fs_info, logical, time_seq);
1198 if (old_root)
1199 eb = alloc_dummy_extent_buffer(logical, root->nodesize);
1200 else
1201 eb = btrfs_clone_extent_buffer(root->node);
1202 btrfs_tree_read_unlock(root->node);
1203 free_extent_buffer(root->node);
1204 if (!eb)
1205 return NULL;
1206 btrfs_tree_read_lock(eb);
1207 if (old_root) {
1208 btrfs_set_header_bytenr(eb, eb->start);
1209 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1210 btrfs_set_header_owner(eb, root->root_key.objectid);
1211 btrfs_set_header_level(eb, old_root->level);
1212 btrfs_set_header_generation(eb, old_generation);
1213 }
1214 if (tm)
1215 __tree_mod_log_rewind(eb, time_seq, tm);
1216 else
1217 WARN_ON(btrfs_header_level(eb) != 0);
1218 extent_buffer_get(eb);
1219
1220 return eb;
1221}
1222
1223static inline int should_cow_block(struct btrfs_trans_handle *trans,
1224 struct btrfs_root *root,
1225 struct extent_buffer *buf)
1226{
1227 /* ensure we can see the force_cow */
1228 smp_rmb();
1229
1230 /*
1231 * We do not need to cow a block if
1232 * 1) this block is not created or changed in this transaction;
1233 * 2) this block does not belong to TREE_RELOC tree;
1234 * 3) the root is not forced COW.
1235 *
1236 * What is forced COW:
1237 * when we create snapshot during commiting the transaction,
1238 * after we've finished coping src root, we must COW the shared
1239 * block to ensure the metadata consistency.
1240 */
1241 if (btrfs_header_generation(buf) == trans->transid &&
1242 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1243 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1244 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1245 !root->force_cow)
1246 return 0;
1247 return 1;
1248}
1249
1250/*
1251 * cows a single block, see __btrfs_cow_block for the real work.
1252 * This version of it has extra checks so that a block isn't cow'd more than
1253 * once per transaction, as long as it hasn't been written yet
1254 */
1255noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1256 struct btrfs_root *root, struct extent_buffer *buf,
1257 struct extent_buffer *parent, int parent_slot,
1258 struct extent_buffer **cow_ret)
1259{
1260 u64 search_start;
1261 int ret;
1262
1263 if (trans->transaction != root->fs_info->running_transaction) {
1264 printk(KERN_CRIT "trans %llu running %llu\n",
1265 (unsigned long long)trans->transid,
1266 (unsigned long long)
1267 root->fs_info->running_transaction->transid);
1268 WARN_ON(1);
1269 }
1270 if (trans->transid != root->fs_info->generation) {
1271 printk(KERN_CRIT "trans %llu running %llu\n",
1272 (unsigned long long)trans->transid,
1273 (unsigned long long)root->fs_info->generation);
1274 WARN_ON(1);
1275 }
1276
1277 if (!should_cow_block(trans, root, buf)) {
1278 *cow_ret = buf;
1279 return 0;
1280 }
1281
1282 search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
1283
1284 if (parent)
1285 btrfs_set_lock_blocking(parent);
1286 btrfs_set_lock_blocking(buf);
1287
1288 ret = __btrfs_cow_block(trans, root, buf, parent,
1289 parent_slot, cow_ret, search_start, 0);
1290
1291 trace_btrfs_cow_block(root, buf, *cow_ret);
1292
1293 return ret;
1294}
1295
1296/*
1297 * helper function for defrag to decide if two blocks pointed to by a
1298 * node are actually close by
1299 */
1300static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1301{
1302 if (blocknr < other && other - (blocknr + blocksize) < 32768)
1303 return 1;
1304 if (blocknr > other && blocknr - (other + blocksize) < 32768)
1305 return 1;
1306 return 0;
1307}
1308
1309/*
1310 * compare two keys in a memcmp fashion
1311 */
1312static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
1313{
1314 struct btrfs_key k1;
1315
1316 btrfs_disk_key_to_cpu(&k1, disk);
1317
1318 return btrfs_comp_cpu_keys(&k1, k2);
1319}
1320
1321/*
1322 * same as comp_keys only with two btrfs_key's
1323 */
1324int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2)
1325{
1326 if (k1->objectid > k2->objectid)
1327 return 1;
1328 if (k1->objectid < k2->objectid)
1329 return -1;
1330 if (k1->type > k2->type)
1331 return 1;
1332 if (k1->type < k2->type)
1333 return -1;
1334 if (k1->offset > k2->offset)
1335 return 1;
1336 if (k1->offset < k2->offset)
1337 return -1;
1338 return 0;
1339}
1340
1341/*
1342 * this is used by the defrag code to go through all the
1343 * leaves pointed to by a node and reallocate them so that
1344 * disk order is close to key order
1345 */
1346int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1347 struct btrfs_root *root, struct extent_buffer *parent,
1348 int start_slot, int cache_only, u64 *last_ret,
1349 struct btrfs_key *progress)
1350{
1351 struct extent_buffer *cur;
1352 u64 blocknr;
1353 u64 gen;
1354 u64 search_start = *last_ret;
1355 u64 last_block = 0;
1356 u64 other;
1357 u32 parent_nritems;
1358 int end_slot;
1359 int i;
1360 int err = 0;
1361 int parent_level;
1362 int uptodate;
1363 u32 blocksize;
1364 int progress_passed = 0;
1365 struct btrfs_disk_key disk_key;
1366
1367 parent_level = btrfs_header_level(parent);
1368 if (cache_only && parent_level != 1)
1369 return 0;
1370
1371 if (trans->transaction != root->fs_info->running_transaction)
1372 WARN_ON(1);
1373 if (trans->transid != root->fs_info->generation)
1374 WARN_ON(1);
1375
1376 parent_nritems = btrfs_header_nritems(parent);
1377 blocksize = btrfs_level_size(root, parent_level - 1);
1378 end_slot = parent_nritems;
1379
1380 if (parent_nritems == 1)
1381 return 0;
1382
1383 btrfs_set_lock_blocking(parent);
1384
1385 for (i = start_slot; i < end_slot; i++) {
1386 int close = 1;
1387
1388 btrfs_node_key(parent, &disk_key, i);
1389 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1390 continue;
1391
1392 progress_passed = 1;
1393 blocknr = btrfs_node_blockptr(parent, i);
1394 gen = btrfs_node_ptr_generation(parent, i);
1395 if (last_block == 0)
1396 last_block = blocknr;
1397
1398 if (i > 0) {
1399 other = btrfs_node_blockptr(parent, i - 1);
1400 close = close_blocks(blocknr, other, blocksize);
1401 }
1402 if (!close && i < end_slot - 2) {
1403 other = btrfs_node_blockptr(parent, i + 1);
1404 close = close_blocks(blocknr, other, blocksize);
1405 }
1406 if (close) {
1407 last_block = blocknr;
1408 continue;
1409 }
1410
1411 cur = btrfs_find_tree_block(root, blocknr, blocksize);
1412 if (cur)
1413 uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1414 else
1415 uptodate = 0;
1416 if (!cur || !uptodate) {
1417 if (cache_only) {
1418 free_extent_buffer(cur);
1419 continue;
1420 }
1421 if (!cur) {
1422 cur = read_tree_block(root, blocknr,
1423 blocksize, gen);
1424 if (!cur)
1425 return -EIO;
1426 } else if (!uptodate) {
1427 err = btrfs_read_buffer(cur, gen);
1428 if (err) {
1429 free_extent_buffer(cur);
1430 return err;
1431 }
1432 }
1433 }
1434 if (search_start == 0)
1435 search_start = last_block;
1436
1437 btrfs_tree_lock(cur);
1438 btrfs_set_lock_blocking(cur);
1439 err = __btrfs_cow_block(trans, root, cur, parent, i,
1440 &cur, search_start,
1441 min(16 * blocksize,
1442 (end_slot - i) * blocksize));
1443 if (err) {
1444 btrfs_tree_unlock(cur);
1445 free_extent_buffer(cur);
1446 break;
1447 }
1448 search_start = cur->start;
1449 last_block = cur->start;
1450 *last_ret = search_start;
1451 btrfs_tree_unlock(cur);
1452 free_extent_buffer(cur);
1453 }
1454 return err;
1455}
1456
1457/*
1458 * The leaf data grows from end-to-front in the node.
1459 * this returns the address of the start of the last item,
1460 * which is the stop of the leaf data stack
1461 */
1462static inline unsigned int leaf_data_end(struct btrfs_root *root,
1463 struct extent_buffer *leaf)
1464{
1465 u32 nr = btrfs_header_nritems(leaf);
1466 if (nr == 0)
1467 return BTRFS_LEAF_DATA_SIZE(root);
1468 return btrfs_item_offset_nr(leaf, nr - 1);
1469}
1470
1471
1472/*
1473 * search for key in the extent_buffer. The items start at offset p,
1474 * and they are item_size apart. There are 'max' items in p.
1475 *
1476 * the slot in the array is returned via slot, and it points to
1477 * the place where you would insert key if it is not found in
1478 * the array.
1479 *
1480 * slot may point to max if the key is bigger than all of the keys
1481 */
1482static noinline int generic_bin_search(struct extent_buffer *eb,
1483 unsigned long p,
1484 int item_size, struct btrfs_key *key,
1485 int max, int *slot)
1486{
1487 int low = 0;
1488 int high = max;
1489 int mid;
1490 int ret;
1491 struct btrfs_disk_key *tmp = NULL;
1492 struct btrfs_disk_key unaligned;
1493 unsigned long offset;
1494 char *kaddr = NULL;
1495 unsigned long map_start = 0;
1496 unsigned long map_len = 0;
1497 int err;
1498
1499 while (low < high) {
1500 mid = (low + high) / 2;
1501 offset = p + mid * item_size;
1502
1503 if (!kaddr || offset < map_start ||
1504 (offset + sizeof(struct btrfs_disk_key)) >
1505 map_start + map_len) {
1506
1507 err = map_private_extent_buffer(eb, offset,
1508 sizeof(struct btrfs_disk_key),
1509 &kaddr, &map_start, &map_len);
1510
1511 if (!err) {
1512 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1513 map_start);
1514 } else {
1515 read_extent_buffer(eb, &unaligned,
1516 offset, sizeof(unaligned));
1517 tmp = &unaligned;
1518 }
1519
1520 } else {
1521 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1522 map_start);
1523 }
1524 ret = comp_keys(tmp, key);
1525
1526 if (ret < 0)
1527 low = mid + 1;
1528 else if (ret > 0)
1529 high = mid;
1530 else {
1531 *slot = mid;
1532 return 0;
1533 }
1534 }
1535 *slot = low;
1536 return 1;
1537}
1538
1539/*
1540 * simple bin_search frontend that does the right thing for
1541 * leaves vs nodes
1542 */
1543static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
1544 int level, int *slot)
1545{
1546 if (level == 0)
1547 return generic_bin_search(eb,
1548 offsetof(struct btrfs_leaf, items),
1549 sizeof(struct btrfs_item),
1550 key, btrfs_header_nritems(eb),
1551 slot);
1552 else
1553 return generic_bin_search(eb,
1554 offsetof(struct btrfs_node, ptrs),
1555 sizeof(struct btrfs_key_ptr),
1556 key, btrfs_header_nritems(eb),
1557 slot);
1558}
1559
1560int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
1561 int level, int *slot)
1562{
1563 return bin_search(eb, key, level, slot);
1564}
1565
1566static void root_add_used(struct btrfs_root *root, u32 size)
1567{
1568 spin_lock(&root->accounting_lock);
1569 btrfs_set_root_used(&root->root_item,
1570 btrfs_root_used(&root->root_item) + size);
1571 spin_unlock(&root->accounting_lock);
1572}
1573
1574static void root_sub_used(struct btrfs_root *root, u32 size)
1575{
1576 spin_lock(&root->accounting_lock);
1577 btrfs_set_root_used(&root->root_item,
1578 btrfs_root_used(&root->root_item) - size);
1579 spin_unlock(&root->accounting_lock);
1580}
1581
1582/* given a node and slot number, this reads the blocks it points to. The
1583 * extent buffer is returned with a reference taken (but unlocked).
1584 * NULL is returned on error.
1585 */
1586static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root,
1587 struct extent_buffer *parent, int slot)
1588{
1589 int level = btrfs_header_level(parent);
1590 if (slot < 0)
1591 return NULL;
1592 if (slot >= btrfs_header_nritems(parent))
1593 return NULL;
1594
1595 BUG_ON(level == 0);
1596
1597 return read_tree_block(root, btrfs_node_blockptr(parent, slot),
1598 btrfs_level_size(root, level - 1),
1599 btrfs_node_ptr_generation(parent, slot));
1600}
1601
1602/*
1603 * node level balancing, used to make sure nodes are in proper order for
1604 * item deletion. We balance from the top down, so we have to make sure
1605 * that a deletion won't leave an node completely empty later on.
1606 */
1607static noinline int balance_level(struct btrfs_trans_handle *trans,
1608 struct btrfs_root *root,
1609 struct btrfs_path *path, int level)
1610{
1611 struct extent_buffer *right = NULL;
1612 struct extent_buffer *mid;
1613 struct extent_buffer *left = NULL;
1614 struct extent_buffer *parent = NULL;
1615 int ret = 0;
1616 int wret;
1617 int pslot;
1618 int orig_slot = path->slots[level];
1619 u64 orig_ptr;
1620
1621 if (level == 0)
1622 return 0;
1623
1624 mid = path->nodes[level];
1625
1626 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1627 path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1628 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1629
1630 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1631
1632 if (level < BTRFS_MAX_LEVEL - 1) {
1633 parent = path->nodes[level + 1];
1634 pslot = path->slots[level + 1];
1635 }
1636
1637 /*
1638 * deal with the case where there is only one pointer in the root
1639 * by promoting the node below to a root
1640 */
1641 if (!parent) {
1642 struct extent_buffer *child;
1643
1644 if (btrfs_header_nritems(mid) != 1)
1645 return 0;
1646
1647 /* promote the child to a root */
1648 child = read_node_slot(root, mid, 0);
1649 if (!child) {
1650 ret = -EROFS;
1651 btrfs_std_error(root->fs_info, ret);
1652 goto enospc;
1653 }
1654
1655 btrfs_tree_lock(child);
1656 btrfs_set_lock_blocking(child);
1657 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1658 if (ret) {
1659 btrfs_tree_unlock(child);
1660 free_extent_buffer(child);
1661 goto enospc;
1662 }
1663
1664 tree_mod_log_set_root_pointer(root, child);
1665 rcu_assign_pointer(root->node, child);
1666
1667 add_root_to_dirty_list(root);
1668 btrfs_tree_unlock(child);
1669
1670 path->locks[level] = 0;
1671 path->nodes[level] = NULL;
1672 clean_tree_block(trans, root, mid);
1673 btrfs_tree_unlock(mid);
1674 /* once for the path */
1675 free_extent_buffer(mid);
1676
1677 root_sub_used(root, mid->len);
1678 btrfs_free_tree_block(trans, root, mid, 0, 1);
1679 /* once for the root ptr */
1680 free_extent_buffer_stale(mid);
1681 return 0;
1682 }
1683 if (btrfs_header_nritems(mid) >
1684 BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
1685 return 0;
1686
1687 left = read_node_slot(root, parent, pslot - 1);
1688 if (left) {
1689 btrfs_tree_lock(left);
1690 btrfs_set_lock_blocking(left);
1691 wret = btrfs_cow_block(trans, root, left,
1692 parent, pslot - 1, &left);
1693 if (wret) {
1694 ret = wret;
1695 goto enospc;
1696 }
1697 }
1698 right = read_node_slot(root, parent, pslot + 1);
1699 if (right) {
1700 btrfs_tree_lock(right);
1701 btrfs_set_lock_blocking(right);
1702 wret = btrfs_cow_block(trans, root, right,
1703 parent, pslot + 1, &right);
1704 if (wret) {
1705 ret = wret;
1706 goto enospc;
1707 }
1708 }
1709
1710 /* first, try to make some room in the middle buffer */
1711 if (left) {
1712 orig_slot += btrfs_header_nritems(left);
1713 wret = push_node_left(trans, root, left, mid, 1);
1714 if (wret < 0)
1715 ret = wret;
1716 }
1717
1718 /*
1719 * then try to empty the right most buffer into the middle
1720 */
1721 if (right) {
1722 wret = push_node_left(trans, root, mid, right, 1);
1723 if (wret < 0 && wret != -ENOSPC)
1724 ret = wret;
1725 if (btrfs_header_nritems(right) == 0) {
1726 clean_tree_block(trans, root, right);
1727 btrfs_tree_unlock(right);
1728 del_ptr(trans, root, path, level + 1, pslot + 1, 1);
1729 root_sub_used(root, right->len);
1730 btrfs_free_tree_block(trans, root, right, 0, 1);
1731 free_extent_buffer_stale(right);
1732 right = NULL;
1733 } else {
1734 struct btrfs_disk_key right_key;
1735 btrfs_node_key(right, &right_key, 0);
1736 tree_mod_log_set_node_key(root->fs_info, parent,
1737 &right_key, pslot + 1, 0);
1738 btrfs_set_node_key(parent, &right_key, pslot + 1);
1739 btrfs_mark_buffer_dirty(parent);
1740 }
1741 }
1742 if (btrfs_header_nritems(mid) == 1) {
1743 /*
1744 * we're not allowed to leave a node with one item in the
1745 * tree during a delete. A deletion from lower in the tree
1746 * could try to delete the only pointer in this node.
1747 * So, pull some keys from the left.
1748 * There has to be a left pointer at this point because
1749 * otherwise we would have pulled some pointers from the
1750 * right
1751 */
1752 if (!left) {
1753 ret = -EROFS;
1754 btrfs_std_error(root->fs_info, ret);
1755 goto enospc;
1756 }
1757 wret = balance_node_right(trans, root, mid, left);
1758 if (wret < 0) {
1759 ret = wret;
1760 goto enospc;
1761 }
1762 if (wret == 1) {
1763 wret = push_node_left(trans, root, left, mid, 1);
1764 if (wret < 0)
1765 ret = wret;
1766 }
1767 BUG_ON(wret == 1);
1768 }
1769 if (btrfs_header_nritems(mid) == 0) {
1770 clean_tree_block(trans, root, mid);
1771 btrfs_tree_unlock(mid);
1772 del_ptr(trans, root, path, level + 1, pslot, 1);
1773 root_sub_used(root, mid->len);
1774 btrfs_free_tree_block(trans, root, mid, 0, 1);
1775 free_extent_buffer_stale(mid);
1776 mid = NULL;
1777 } else {
1778 /* update the parent key to reflect our changes */
1779 struct btrfs_disk_key mid_key;
1780 btrfs_node_key(mid, &mid_key, 0);
1781 tree_mod_log_set_node_key(root->fs_info, parent, &mid_key,
1782 pslot, 0);
1783 btrfs_set_node_key(parent, &mid_key, pslot);
1784 btrfs_mark_buffer_dirty(parent);
1785 }
1786
1787 /* update the path */
1788 if (left) {
1789 if (btrfs_header_nritems(left) > orig_slot) {
1790 extent_buffer_get(left);
1791 /* left was locked after cow */
1792 path->nodes[level] = left;
1793 path->slots[level + 1] -= 1;
1794 path->slots[level] = orig_slot;
1795 if (mid) {
1796 btrfs_tree_unlock(mid);
1797 free_extent_buffer(mid);
1798 }
1799 } else {
1800 orig_slot -= btrfs_header_nritems(left);
1801 path->slots[level] = orig_slot;
1802 }
1803 }
1804 /* double check we haven't messed things up */
1805 if (orig_ptr !=
1806 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1807 BUG();
1808enospc:
1809 if (right) {
1810 btrfs_tree_unlock(right);
1811 free_extent_buffer(right);
1812 }
1813 if (left) {
1814 if (path->nodes[level] != left)
1815 btrfs_tree_unlock(left);
1816 free_extent_buffer(left);
1817 }
1818 return ret;
1819}
1820
1821/* Node balancing for insertion. Here we only split or push nodes around
1822 * when they are completely full. This is also done top down, so we
1823 * have to be pessimistic.
1824 */
1825static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1826 struct btrfs_root *root,
1827 struct btrfs_path *path, int level)
1828{
1829 struct extent_buffer *right = NULL;
1830 struct extent_buffer *mid;
1831 struct extent_buffer *left = NULL;
1832 struct extent_buffer *parent = NULL;
1833 int ret = 0;
1834 int wret;
1835 int pslot;
1836 int orig_slot = path->slots[level];
1837
1838 if (level == 0)
1839 return 1;
1840
1841 mid = path->nodes[level];
1842 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1843
1844 if (level < BTRFS_MAX_LEVEL - 1) {
1845 parent = path->nodes[level + 1];
1846 pslot = path->slots[level + 1];
1847 }
1848
1849 if (!parent)
1850 return 1;
1851
1852 left = read_node_slot(root, parent, pslot - 1);
1853
1854 /* first, try to make some room in the middle buffer */
1855 if (left) {
1856 u32 left_nr;
1857
1858 btrfs_tree_lock(left);
1859 btrfs_set_lock_blocking(left);
1860
1861 left_nr = btrfs_header_nritems(left);
1862 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1863 wret = 1;
1864 } else {
1865 ret = btrfs_cow_block(trans, root, left, parent,
1866 pslot - 1, &left);
1867 if (ret)
1868 wret = 1;
1869 else {
1870 wret = push_node_left(trans, root,
1871 left, mid, 0);
1872 }
1873 }
1874 if (wret < 0)
1875 ret = wret;
1876 if (wret == 0) {
1877 struct btrfs_disk_key disk_key;
1878 orig_slot += left_nr;
1879 btrfs_node_key(mid, &disk_key, 0);
1880 tree_mod_log_set_node_key(root->fs_info, parent,
1881 &disk_key, pslot, 0);
1882 btrfs_set_node_key(parent, &disk_key, pslot);
1883 btrfs_mark_buffer_dirty(parent);
1884 if (btrfs_header_nritems(left) > orig_slot) {
1885 path->nodes[level] = left;
1886 path->slots[level + 1] -= 1;
1887 path->slots[level] = orig_slot;
1888 btrfs_tree_unlock(mid);
1889 free_extent_buffer(mid);
1890 } else {
1891 orig_slot -=
1892 btrfs_header_nritems(left);
1893 path->slots[level] = orig_slot;
1894 btrfs_tree_unlock(left);
1895 free_extent_buffer(left);
1896 }
1897 return 0;
1898 }
1899 btrfs_tree_unlock(left);
1900 free_extent_buffer(left);
1901 }
1902 right = read_node_slot(root, parent, pslot + 1);
1903
1904 /*
1905 * then try to empty the right most buffer into the middle
1906 */
1907 if (right) {
1908 u32 right_nr;
1909
1910 btrfs_tree_lock(right);
1911 btrfs_set_lock_blocking(right);
1912
1913 right_nr = btrfs_header_nritems(right);
1914 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1915 wret = 1;
1916 } else {
1917 ret = btrfs_cow_block(trans, root, right,
1918 parent, pslot + 1,
1919 &right);
1920 if (ret)
1921 wret = 1;
1922 else {
1923 wret = balance_node_right(trans, root,
1924 right, mid);
1925 }
1926 }
1927 if (wret < 0)
1928 ret = wret;
1929 if (wret == 0) {
1930 struct btrfs_disk_key disk_key;
1931
1932 btrfs_node_key(right, &disk_key, 0);
1933 tree_mod_log_set_node_key(root->fs_info, parent,
1934 &disk_key, pslot + 1, 0);
1935 btrfs_set_node_key(parent, &disk_key, pslot + 1);
1936 btrfs_mark_buffer_dirty(parent);
1937
1938 if (btrfs_header_nritems(mid) <= orig_slot) {
1939 path->nodes[level] = right;
1940 path->slots[level + 1] += 1;
1941 path->slots[level] = orig_slot -
1942 btrfs_header_nritems(mid);
1943 btrfs_tree_unlock(mid);
1944 free_extent_buffer(mid);
1945 } else {
1946 btrfs_tree_unlock(right);
1947 free_extent_buffer(right);
1948 }
1949 return 0;
1950 }
1951 btrfs_tree_unlock(right);
1952 free_extent_buffer(right);
1953 }
1954 return 1;
1955}
1956
1957/*
1958 * readahead one full node of leaves, finding things that are close
1959 * to the block in 'slot', and triggering ra on them.
1960 */
1961static void reada_for_search(struct btrfs_root *root,
1962 struct btrfs_path *path,
1963 int level, int slot, u64 objectid)
1964{
1965 struct extent_buffer *node;
1966 struct btrfs_disk_key disk_key;
1967 u32 nritems;
1968 u64 search;
1969 u64 target;
1970 u64 nread = 0;
1971 u64 gen;
1972 int direction = path->reada;
1973 struct extent_buffer *eb;
1974 u32 nr;
1975 u32 blocksize;
1976 u32 nscan = 0;
1977
1978 if (level != 1)
1979 return;
1980
1981 if (!path->nodes[level])
1982 return;
1983
1984 node = path->nodes[level];
1985
1986 search = btrfs_node_blockptr(node, slot);
1987 blocksize = btrfs_level_size(root, level - 1);
1988 eb = btrfs_find_tree_block(root, search, blocksize);
1989 if (eb) {
1990 free_extent_buffer(eb);
1991 return;
1992 }
1993
1994 target = search;
1995
1996 nritems = btrfs_header_nritems(node);
1997 nr = slot;
1998
1999 while (1) {
2000 if (direction < 0) {
2001 if (nr == 0)
2002 break;
2003 nr--;
2004 } else if (direction > 0) {
2005 nr++;
2006 if (nr >= nritems)
2007 break;
2008 }
2009 if (path->reada < 0 && objectid) {
2010 btrfs_node_key(node, &disk_key, nr);
2011 if (btrfs_disk_key_objectid(&disk_key) != objectid)
2012 break;
2013 }
2014 search = btrfs_node_blockptr(node, nr);
2015 if ((search <= target && target - search <= 65536) ||
2016 (search > target && search - target <= 65536)) {
2017 gen = btrfs_node_ptr_generation(node, nr);
2018 readahead_tree_block(root, search, blocksize, gen);
2019 nread += blocksize;
2020 }
2021 nscan++;
2022 if ((nread > 65536 || nscan > 32))
2023 break;
2024 }
2025}
2026
2027/*
2028 * returns -EAGAIN if it had to drop the path, or zero if everything was in
2029 * cache
2030 */
2031static noinline int reada_for_balance(struct btrfs_root *root,
2032 struct btrfs_path *path, int level)
2033{
2034 int slot;
2035 int nritems;
2036 struct extent_buffer *parent;
2037 struct extent_buffer *eb;
2038 u64 gen;
2039 u64 block1 = 0;
2040 u64 block2 = 0;
2041 int ret = 0;
2042 int blocksize;
2043
2044 parent = path->nodes[level + 1];
2045 if (!parent)
2046 return 0;
2047
2048 nritems = btrfs_header_nritems(parent);
2049 slot = path->slots[level + 1];
2050 blocksize = btrfs_level_size(root, level);
2051
2052 if (slot > 0) {
2053 block1 = btrfs_node_blockptr(parent, slot - 1);
2054 gen = btrfs_node_ptr_generation(parent, slot - 1);
2055 eb = btrfs_find_tree_block(root, block1, blocksize);
2056 /*
2057 * if we get -eagain from btrfs_buffer_uptodate, we
2058 * don't want to return eagain here. That will loop
2059 * forever
2060 */
2061 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2062 block1 = 0;
2063 free_extent_buffer(eb);
2064 }
2065 if (slot + 1 < nritems) {
2066 block2 = btrfs_node_blockptr(parent, slot + 1);
2067 gen = btrfs_node_ptr_generation(parent, slot + 1);
2068 eb = btrfs_find_tree_block(root, block2, blocksize);
2069 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2070 block2 = 0;
2071 free_extent_buffer(eb);
2072 }
2073 if (block1 || block2) {
2074 ret = -EAGAIN;
2075
2076 /* release the whole path */
2077 btrfs_release_path(path);
2078
2079 /* read the blocks */
2080 if (block1)
2081 readahead_tree_block(root, block1, blocksize, 0);
2082 if (block2)
2083 readahead_tree_block(root, block2, blocksize, 0);
2084
2085 if (block1) {
2086 eb = read_tree_block(root, block1, blocksize, 0);
2087 free_extent_buffer(eb);
2088 }
2089 if (block2) {
2090 eb = read_tree_block(root, block2, blocksize, 0);
2091 free_extent_buffer(eb);
2092 }
2093 }
2094 return ret;
2095}
2096
2097
2098/*
2099 * when we walk down the tree, it is usually safe to unlock the higher layers
2100 * in the tree. The exceptions are when our path goes through slot 0, because
2101 * operations on the tree might require changing key pointers higher up in the
2102 * tree.
2103 *
2104 * callers might also have set path->keep_locks, which tells this code to keep
2105 * the lock if the path points to the last slot in the block. This is part of
2106 * walking through the tree, and selecting the next slot in the higher block.
2107 *
2108 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
2109 * if lowest_unlock is 1, level 0 won't be unlocked
2110 */
2111static noinline void unlock_up(struct btrfs_path *path, int level,
2112 int lowest_unlock, int min_write_lock_level,
2113 int *write_lock_level)
2114{
2115 int i;
2116 int skip_level = level;
2117 int no_skips = 0;
2118 struct extent_buffer *t;
2119
2120 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2121 if (!path->nodes[i])
2122 break;
2123 if (!path->locks[i])
2124 break;
2125 if (!no_skips && path->slots[i] == 0) {
2126 skip_level = i + 1;
2127 continue;
2128 }
2129 if (!no_skips && path->keep_locks) {
2130 u32 nritems;
2131 t = path->nodes[i];
2132 nritems = btrfs_header_nritems(t);
2133 if (nritems < 1 || path->slots[i] >= nritems - 1) {
2134 skip_level = i + 1;
2135 continue;
2136 }
2137 }
2138 if (skip_level < i && i >= lowest_unlock)
2139 no_skips = 1;
2140
2141 t = path->nodes[i];
2142 if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
2143 btrfs_tree_unlock_rw(t, path->locks[i]);
2144 path->locks[i] = 0;
2145 if (write_lock_level &&
2146 i > min_write_lock_level &&
2147 i <= *write_lock_level) {
2148 *write_lock_level = i - 1;
2149 }
2150 }
2151 }
2152}
2153
2154/*
2155 * This releases any locks held in the path starting at level and
2156 * going all the way up to the root.
2157 *
2158 * btrfs_search_slot will keep the lock held on higher nodes in a few
2159 * corner cases, such as COW of the block at slot zero in the node. This
2160 * ignores those rules, and it should only be called when there are no
2161 * more updates to be done higher up in the tree.
2162 */
2163noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
2164{
2165 int i;
2166
2167 if (path->keep_locks)
2168 return;
2169
2170 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2171 if (!path->nodes[i])
2172 continue;
2173 if (!path->locks[i])
2174 continue;
2175 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
2176 path->locks[i] = 0;
2177 }
2178}
2179
2180/*
2181 * helper function for btrfs_search_slot. The goal is to find a block
2182 * in cache without setting the path to blocking. If we find the block
2183 * we return zero and the path is unchanged.
2184 *
2185 * If we can't find the block, we set the path blocking and do some
2186 * reada. -EAGAIN is returned and the search must be repeated.
2187 */
2188static int
2189read_block_for_search(struct btrfs_trans_handle *trans,
2190 struct btrfs_root *root, struct btrfs_path *p,
2191 struct extent_buffer **eb_ret, int level, int slot,
2192 struct btrfs_key *key, u64 time_seq)
2193{
2194 u64 blocknr;
2195 u64 gen;
2196 u32 blocksize;
2197 struct extent_buffer *b = *eb_ret;
2198 struct extent_buffer *tmp;
2199 int ret;
2200
2201 blocknr = btrfs_node_blockptr(b, slot);
2202 gen = btrfs_node_ptr_generation(b, slot);
2203 blocksize = btrfs_level_size(root, level - 1);
2204
2205 tmp = btrfs_find_tree_block(root, blocknr, blocksize);
2206 if (tmp) {
2207 /* first we do an atomic uptodate check */
2208 if (btrfs_buffer_uptodate(tmp, 0, 1) > 0) {
2209 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2210 /*
2211 * we found an up to date block without
2212 * sleeping, return
2213 * right away
2214 */
2215 *eb_ret = tmp;
2216 return 0;
2217 }
2218 /* the pages were up to date, but we failed
2219 * the generation number check. Do a full
2220 * read for the generation number that is correct.
2221 * We must do this without dropping locks so
2222 * we can trust our generation number
2223 */
2224 free_extent_buffer(tmp);
2225 btrfs_set_path_blocking(p);
2226
2227 /* now we're allowed to do a blocking uptodate check */
2228 tmp = read_tree_block(root, blocknr, blocksize, gen);
2229 if (tmp && btrfs_buffer_uptodate(tmp, gen, 0) > 0) {
2230 *eb_ret = tmp;
2231 return 0;
2232 }
2233 free_extent_buffer(tmp);
2234 btrfs_release_path(p);
2235 return -EIO;
2236 }
2237 }
2238
2239 /*
2240 * reduce lock contention at high levels
2241 * of the btree by dropping locks before
2242 * we read. Don't release the lock on the current
2243 * level because we need to walk this node to figure
2244 * out which blocks to read.
2245 */
2246 btrfs_unlock_up_safe(p, level + 1);
2247 btrfs_set_path_blocking(p);
2248
2249 free_extent_buffer(tmp);
2250 if (p->reada)
2251 reada_for_search(root, p, level, slot, key->objectid);
2252
2253 btrfs_release_path(p);
2254
2255 ret = -EAGAIN;
2256 tmp = read_tree_block(root, blocknr, blocksize, 0);
2257 if (tmp) {
2258 /*
2259 * If the read above didn't mark this buffer up to date,
2260 * it will never end up being up to date. Set ret to EIO now
2261 * and give up so that our caller doesn't loop forever
2262 * on our EAGAINs.
2263 */
2264 if (!btrfs_buffer_uptodate(tmp, 0, 0))
2265 ret = -EIO;
2266 free_extent_buffer(tmp);
2267 }
2268 return ret;
2269}
2270
2271/*
2272 * helper function for btrfs_search_slot. This does all of the checks
2273 * for node-level blocks and does any balancing required based on
2274 * the ins_len.
2275 *
2276 * If no extra work was required, zero is returned. If we had to
2277 * drop the path, -EAGAIN is returned and btrfs_search_slot must
2278 * start over
2279 */
2280static int
2281setup_nodes_for_search(struct btrfs_trans_handle *trans,
2282 struct btrfs_root *root, struct btrfs_path *p,
2283 struct extent_buffer *b, int level, int ins_len,
2284 int *write_lock_level)
2285{
2286 int ret;
2287 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2288 BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
2289 int sret;
2290
2291 if (*write_lock_level < level + 1) {
2292 *write_lock_level = level + 1;
2293 btrfs_release_path(p);
2294 goto again;
2295 }
2296
2297 sret = reada_for_balance(root, p, level);
2298 if (sret)
2299 goto again;
2300
2301 btrfs_set_path_blocking(p);
2302 sret = split_node(trans, root, p, level);
2303 btrfs_clear_path_blocking(p, NULL, 0);
2304
2305 BUG_ON(sret > 0);
2306 if (sret) {
2307 ret = sret;
2308 goto done;
2309 }
2310 b = p->nodes[level];
2311 } else if (ins_len < 0 && btrfs_header_nritems(b) <
2312 BTRFS_NODEPTRS_PER_BLOCK(root) / 2) {
2313 int sret;
2314
2315 if (*write_lock_level < level + 1) {
2316 *write_lock_level = level + 1;
2317 btrfs_release_path(p);
2318 goto again;
2319 }
2320
2321 sret = reada_for_balance(root, p, level);
2322 if (sret)
2323 goto again;
2324
2325 btrfs_set_path_blocking(p);
2326 sret = balance_level(trans, root, p, level);
2327 btrfs_clear_path_blocking(p, NULL, 0);
2328
2329 if (sret) {
2330 ret = sret;
2331 goto done;
2332 }
2333 b = p->nodes[level];
2334 if (!b) {
2335 btrfs_release_path(p);
2336 goto again;
2337 }
2338 BUG_ON(btrfs_header_nritems(b) == 1);
2339 }
2340 return 0;
2341
2342again:
2343 ret = -EAGAIN;
2344done:
2345 return ret;
2346}
2347
2348/*
2349 * look for key in the tree. path is filled in with nodes along the way
2350 * if key is found, we return zero and you can find the item in the leaf
2351 * level of the path (level 0)
2352 *
2353 * If the key isn't found, the path points to the slot where it should
2354 * be inserted, and 1 is returned. If there are other errors during the
2355 * search a negative error number is returned.
2356 *
2357 * if ins_len > 0, nodes and leaves will be split as we walk down the
2358 * tree. if ins_len < 0, nodes will be merged as we walk down the tree (if
2359 * possible)
2360 */
2361int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
2362 *root, struct btrfs_key *key, struct btrfs_path *p, int
2363 ins_len, int cow)
2364{
2365 struct extent_buffer *b;
2366 int slot;
2367 int ret;
2368 int err;
2369 int level;
2370 int lowest_unlock = 1;
2371 int root_lock;
2372 /* everything at write_lock_level or lower must be write locked */
2373 int write_lock_level = 0;
2374 u8 lowest_level = 0;
2375 int min_write_lock_level;
2376
2377 lowest_level = p->lowest_level;
2378 WARN_ON(lowest_level && ins_len > 0);
2379 WARN_ON(p->nodes[0] != NULL);
2380
2381 if (ins_len < 0) {
2382 lowest_unlock = 2;
2383
2384 /* when we are removing items, we might have to go up to level
2385 * two as we update tree pointers Make sure we keep write
2386 * for those levels as well
2387 */
2388 write_lock_level = 2;
2389 } else if (ins_len > 0) {
2390 /*
2391 * for inserting items, make sure we have a write lock on
2392 * level 1 so we can update keys
2393 */
2394 write_lock_level = 1;
2395 }
2396
2397 if (!cow)
2398 write_lock_level = -1;
2399
2400 if (cow && (p->keep_locks || p->lowest_level))
2401 write_lock_level = BTRFS_MAX_LEVEL;
2402
2403 min_write_lock_level = write_lock_level;
2404
2405again:
2406 /*
2407 * we try very hard to do read locks on the root
2408 */
2409 root_lock = BTRFS_READ_LOCK;
2410 level = 0;
2411 if (p->search_commit_root) {
2412 /*
2413 * the commit roots are read only
2414 * so we always do read locks
2415 */
2416 b = root->commit_root;
2417 extent_buffer_get(b);
2418 level = btrfs_header_level(b);
2419 if (!p->skip_locking)
2420 btrfs_tree_read_lock(b);
2421 } else {
2422 if (p->skip_locking) {
2423 b = btrfs_root_node(root);
2424 level = btrfs_header_level(b);
2425 } else {
2426 /* we don't know the level of the root node
2427 * until we actually have it read locked
2428 */
2429 b = btrfs_read_lock_root_node(root);
2430 level = btrfs_header_level(b);
2431 if (level <= write_lock_level) {
2432 /* whoops, must trade for write lock */
2433 btrfs_tree_read_unlock(b);
2434 free_extent_buffer(b);
2435 b = btrfs_lock_root_node(root);
2436 root_lock = BTRFS_WRITE_LOCK;
2437
2438 /* the level might have changed, check again */
2439 level = btrfs_header_level(b);
2440 }
2441 }
2442 }
2443 p->nodes[level] = b;
2444 if (!p->skip_locking)
2445 p->locks[level] = root_lock;
2446
2447 while (b) {
2448 level = btrfs_header_level(b);
2449
2450 /*
2451 * setup the path here so we can release it under lock
2452 * contention with the cow code
2453 */
2454 if (cow) {
2455 /*
2456 * if we don't really need to cow this block
2457 * then we don't want to set the path blocking,
2458 * so we test it here
2459 */
2460 if (!should_cow_block(trans, root, b))
2461 goto cow_done;
2462
2463 btrfs_set_path_blocking(p);
2464
2465 /*
2466 * must have write locks on this node and the
2467 * parent
2468 */
2469 if (level + 1 > write_lock_level) {
2470 write_lock_level = level + 1;
2471 btrfs_release_path(p);
2472 goto again;
2473 }
2474
2475 err = btrfs_cow_block(trans, root, b,
2476 p->nodes[level + 1],
2477 p->slots[level + 1], &b);
2478 if (err) {
2479 ret = err;
2480 goto done;
2481 }
2482 }
2483cow_done:
2484 BUG_ON(!cow && ins_len);
2485
2486 p->nodes[level] = b;
2487 btrfs_clear_path_blocking(p, NULL, 0);
2488
2489 /*
2490 * we have a lock on b and as long as we aren't changing
2491 * the tree, there is no way to for the items in b to change.
2492 * It is safe to drop the lock on our parent before we
2493 * go through the expensive btree search on b.
2494 *
2495 * If cow is true, then we might be changing slot zero,
2496 * which may require changing the parent. So, we can't
2497 * drop the lock until after we know which slot we're
2498 * operating on.
2499 */
2500 if (!cow)
2501 btrfs_unlock_up_safe(p, level + 1);
2502
2503 ret = bin_search(b, key, level, &slot);
2504
2505 if (level != 0) {
2506 int dec = 0;
2507 if (ret && slot > 0) {
2508 dec = 1;
2509 slot -= 1;
2510 }
2511 p->slots[level] = slot;
2512 err = setup_nodes_for_search(trans, root, p, b, level,
2513 ins_len, &write_lock_level);
2514 if (err == -EAGAIN)
2515 goto again;
2516 if (err) {
2517 ret = err;
2518 goto done;
2519 }
2520 b = p->nodes[level];
2521 slot = p->slots[level];
2522
2523 /*
2524 * slot 0 is special, if we change the key
2525 * we have to update the parent pointer
2526 * which means we must have a write lock
2527 * on the parent
2528 */
2529 if (slot == 0 && cow &&
2530 write_lock_level < level + 1) {
2531 write_lock_level = level + 1;
2532 btrfs_release_path(p);
2533 goto again;
2534 }
2535
2536 unlock_up(p, level, lowest_unlock,
2537 min_write_lock_level, &write_lock_level);
2538
2539 if (level == lowest_level) {
2540 if (dec)
2541 p->slots[level]++;
2542 goto done;
2543 }
2544
2545 err = read_block_for_search(trans, root, p,
2546 &b, level, slot, key, 0);
2547 if (err == -EAGAIN)
2548 goto again;
2549 if (err) {
2550 ret = err;
2551 goto done;
2552 }
2553
2554 if (!p->skip_locking) {
2555 level = btrfs_header_level(b);
2556 if (level <= write_lock_level) {
2557 err = btrfs_try_tree_write_lock(b);
2558 if (!err) {
2559 btrfs_set_path_blocking(p);
2560 btrfs_tree_lock(b);
2561 btrfs_clear_path_blocking(p, b,
2562 BTRFS_WRITE_LOCK);
2563 }
2564 p->locks[level] = BTRFS_WRITE_LOCK;
2565 } else {
2566 err = btrfs_try_tree_read_lock(b);
2567 if (!err) {
2568 btrfs_set_path_blocking(p);
2569 btrfs_tree_read_lock(b);
2570 btrfs_clear_path_blocking(p, b,
2571 BTRFS_READ_LOCK);
2572 }
2573 p->locks[level] = BTRFS_READ_LOCK;
2574 }
2575 p->nodes[level] = b;
2576 }
2577 } else {
2578 p->slots[level] = slot;
2579 if (ins_len > 0 &&
2580 btrfs_leaf_free_space(root, b) < ins_len) {
2581 if (write_lock_level < 1) {
2582 write_lock_level = 1;
2583 btrfs_release_path(p);
2584 goto again;
2585 }
2586
2587 btrfs_set_path_blocking(p);
2588 err = split_leaf(trans, root, key,
2589 p, ins_len, ret == 0);
2590 btrfs_clear_path_blocking(p, NULL, 0);
2591
2592 BUG_ON(err > 0);
2593 if (err) {
2594 ret = err;
2595 goto done;
2596 }
2597 }
2598 if (!p->search_for_split)
2599 unlock_up(p, level, lowest_unlock,
2600 min_write_lock_level, &write_lock_level);
2601 goto done;
2602 }
2603 }
2604 ret = 1;
2605done:
2606 /*
2607 * we don't really know what they plan on doing with the path
2608 * from here on, so for now just mark it as blocking
2609 */
2610 if (!p->leave_spinning)
2611 btrfs_set_path_blocking(p);
2612 if (ret < 0)
2613 btrfs_release_path(p);
2614 return ret;
2615}
2616
2617/*
2618 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2619 * current state of the tree together with the operations recorded in the tree
2620 * modification log to search for the key in a previous version of this tree, as
2621 * denoted by the time_seq parameter.
2622 *
2623 * Naturally, there is no support for insert, delete or cow operations.
2624 *
2625 * The resulting path and return value will be set up as if we called
2626 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2627 */
2628int btrfs_search_old_slot(struct btrfs_root *root, struct btrfs_key *key,
2629 struct btrfs_path *p, u64 time_seq)
2630{
2631 struct extent_buffer *b;
2632 int slot;
2633 int ret;
2634 int err;
2635 int level;
2636 int lowest_unlock = 1;
2637 u8 lowest_level = 0;
2638
2639 lowest_level = p->lowest_level;
2640 WARN_ON(p->nodes[0] != NULL);
2641
2642 if (p->search_commit_root) {
2643 BUG_ON(time_seq);
2644 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2645 }
2646
2647again:
2648 b = get_old_root(root, time_seq);
2649 level = btrfs_header_level(b);
2650 p->locks[level] = BTRFS_READ_LOCK;
2651
2652 while (b) {
2653 level = btrfs_header_level(b);
2654 p->nodes[level] = b;
2655 btrfs_clear_path_blocking(p, NULL, 0);
2656
2657 /*
2658 * we have a lock on b and as long as we aren't changing
2659 * the tree, there is no way to for the items in b to change.
2660 * It is safe to drop the lock on our parent before we
2661 * go through the expensive btree search on b.
2662 */
2663 btrfs_unlock_up_safe(p, level + 1);
2664
2665 ret = bin_search(b, key, level, &slot);
2666
2667 if (level != 0) {
2668 int dec = 0;
2669 if (ret && slot > 0) {
2670 dec = 1;
2671 slot -= 1;
2672 }
2673 p->slots[level] = slot;
2674 unlock_up(p, level, lowest_unlock, 0, NULL);
2675
2676 if (level == lowest_level) {
2677 if (dec)
2678 p->slots[level]++;
2679 goto done;
2680 }
2681
2682 err = read_block_for_search(NULL, root, p, &b, level,
2683 slot, key, time_seq);
2684 if (err == -EAGAIN)
2685 goto again;
2686 if (err) {
2687 ret = err;
2688 goto done;
2689 }
2690
2691 level = btrfs_header_level(b);
2692 err = btrfs_try_tree_read_lock(b);
2693 if (!err) {
2694 btrfs_set_path_blocking(p);
2695 btrfs_tree_read_lock(b);
2696 btrfs_clear_path_blocking(p, b,
2697 BTRFS_READ_LOCK);
2698 }
2699 p->locks[level] = BTRFS_READ_LOCK;
2700 p->nodes[level] = b;
2701 b = tree_mod_log_rewind(root->fs_info, b, time_seq);
2702 if (b != p->nodes[level]) {
2703 btrfs_tree_unlock_rw(p->nodes[level],
2704 p->locks[level]);
2705 p->locks[level] = 0;
2706 p->nodes[level] = b;
2707 }
2708 } else {
2709 p->slots[level] = slot;
2710 unlock_up(p, level, lowest_unlock, 0, NULL);
2711 goto done;
2712 }
2713 }
2714 ret = 1;
2715done:
2716 if (!p->leave_spinning)
2717 btrfs_set_path_blocking(p);
2718 if (ret < 0)
2719 btrfs_release_path(p);
2720
2721 return ret;
2722}
2723
2724/*
2725 * adjust the pointers going up the tree, starting at level
2726 * making sure the right key of each node is points to 'key'.
2727 * This is used after shifting pointers to the left, so it stops
2728 * fixing up pointers when a given leaf/node is not in slot 0 of the
2729 * higher levels
2730 *
2731 */
2732static void fixup_low_keys(struct btrfs_trans_handle *trans,
2733 struct btrfs_root *root, struct btrfs_path *path,
2734 struct btrfs_disk_key *key, int level)
2735{
2736 int i;
2737 struct extent_buffer *t;
2738
2739 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2740 int tslot = path->slots[i];
2741 if (!path->nodes[i])
2742 break;
2743 t = path->nodes[i];
2744 tree_mod_log_set_node_key(root->fs_info, t, key, tslot, 1);
2745 btrfs_set_node_key(t, key, tslot);
2746 btrfs_mark_buffer_dirty(path->nodes[i]);
2747 if (tslot != 0)
2748 break;
2749 }
2750}
2751
2752/*
2753 * update item key.
2754 *
2755 * This function isn't completely safe. It's the caller's responsibility
2756 * that the new key won't break the order
2757 */
2758void btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
2759 struct btrfs_root *root, struct btrfs_path *path,
2760 struct btrfs_key *new_key)
2761{
2762 struct btrfs_disk_key disk_key;
2763 struct extent_buffer *eb;
2764 int slot;
2765
2766 eb = path->nodes[0];
2767 slot = path->slots[0];
2768 if (slot > 0) {
2769 btrfs_item_key(eb, &disk_key, slot - 1);
2770 BUG_ON(comp_keys(&disk_key, new_key) >= 0);
2771 }
2772 if (slot < btrfs_header_nritems(eb) - 1) {
2773 btrfs_item_key(eb, &disk_key, slot + 1);
2774 BUG_ON(comp_keys(&disk_key, new_key) <= 0);
2775 }
2776
2777 btrfs_cpu_key_to_disk(&disk_key, new_key);
2778 btrfs_set_item_key(eb, &disk_key, slot);
2779 btrfs_mark_buffer_dirty(eb);
2780 if (slot == 0)
2781 fixup_low_keys(trans, root, path, &disk_key, 1);
2782}
2783
2784/*
2785 * try to push data from one node into the next node left in the
2786 * tree.
2787 *
2788 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2789 * error, and > 0 if there was no room in the left hand block.
2790 */
2791static int push_node_left(struct btrfs_trans_handle *trans,
2792 struct btrfs_root *root, struct extent_buffer *dst,
2793 struct extent_buffer *src, int empty)
2794{
2795 int push_items = 0;
2796 int src_nritems;
2797 int dst_nritems;
2798 int ret = 0;
2799
2800 src_nritems = btrfs_header_nritems(src);
2801 dst_nritems = btrfs_header_nritems(dst);
2802 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
2803 WARN_ON(btrfs_header_generation(src) != trans->transid);
2804 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2805
2806 if (!empty && src_nritems <= 8)
2807 return 1;
2808
2809 if (push_items <= 0)
2810 return 1;
2811
2812 if (empty) {
2813 push_items = min(src_nritems, push_items);
2814 if (push_items < src_nritems) {
2815 /* leave at least 8 pointers in the node if
2816 * we aren't going to empty it
2817 */
2818 if (src_nritems - push_items < 8) {
2819 if (push_items <= 8)
2820 return 1;
2821 push_items -= 8;
2822 }
2823 }
2824 } else
2825 push_items = min(src_nritems - 8, push_items);
2826
2827 tree_mod_log_eb_copy(root->fs_info, dst, src, dst_nritems, 0,
2828 push_items);
2829 copy_extent_buffer(dst, src,
2830 btrfs_node_key_ptr_offset(dst_nritems),
2831 btrfs_node_key_ptr_offset(0),
2832 push_items * sizeof(struct btrfs_key_ptr));
2833
2834 if (push_items < src_nritems) {
2835 tree_mod_log_eb_move(root->fs_info, src, 0, push_items,
2836 src_nritems - push_items);
2837 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
2838 btrfs_node_key_ptr_offset(push_items),
2839 (src_nritems - push_items) *
2840 sizeof(struct btrfs_key_ptr));
2841 }
2842 btrfs_set_header_nritems(src, src_nritems - push_items);
2843 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2844 btrfs_mark_buffer_dirty(src);
2845 btrfs_mark_buffer_dirty(dst);
2846
2847 return ret;
2848}
2849
2850/*
2851 * try to push data from one node into the next node right in the
2852 * tree.
2853 *
2854 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
2855 * error, and > 0 if there was no room in the right hand block.
2856 *
2857 * this will only push up to 1/2 the contents of the left node over
2858 */
2859static int balance_node_right(struct btrfs_trans_handle *trans,
2860 struct btrfs_root *root,
2861 struct extent_buffer *dst,
2862 struct extent_buffer *src)
2863{
2864 int push_items = 0;
2865 int max_push;
2866 int src_nritems;
2867 int dst_nritems;
2868 int ret = 0;
2869
2870 WARN_ON(btrfs_header_generation(src) != trans->transid);
2871 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2872
2873 src_nritems = btrfs_header_nritems(src);
2874 dst_nritems = btrfs_header_nritems(dst);
2875 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
2876 if (push_items <= 0)
2877 return 1;
2878
2879 if (src_nritems < 4)
2880 return 1;
2881
2882 max_push = src_nritems / 2 + 1;
2883 /* don't try to empty the node */
2884 if (max_push >= src_nritems)
2885 return 1;
2886
2887 if (max_push < push_items)
2888 push_items = max_push;
2889
2890 tree_mod_log_eb_move(root->fs_info, dst, push_items, 0, dst_nritems);
2891 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
2892 btrfs_node_key_ptr_offset(0),
2893 (dst_nritems) *
2894 sizeof(struct btrfs_key_ptr));
2895
2896 tree_mod_log_eb_copy(root->fs_info, dst, src, 0,
2897 src_nritems - push_items, push_items);
2898 copy_extent_buffer(dst, src,
2899 btrfs_node_key_ptr_offset(0),
2900 btrfs_node_key_ptr_offset(src_nritems - push_items),
2901 push_items * sizeof(struct btrfs_key_ptr));
2902
2903 btrfs_set_header_nritems(src, src_nritems - push_items);
2904 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2905
2906 btrfs_mark_buffer_dirty(src);
2907 btrfs_mark_buffer_dirty(dst);
2908
2909 return ret;
2910}
2911
2912/*
2913 * helper function to insert a new root level in the tree.
2914 * A new node is allocated, and a single item is inserted to
2915 * point to the existing root
2916 *
2917 * returns zero on success or < 0 on failure.
2918 */
2919static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2920 struct btrfs_root *root,
2921 struct btrfs_path *path, int level)
2922{
2923 u64 lower_gen;
2924 struct extent_buffer *lower;
2925 struct extent_buffer *c;
2926 struct extent_buffer *old;
2927 struct btrfs_disk_key lower_key;
2928
2929 BUG_ON(path->nodes[level]);
2930 BUG_ON(path->nodes[level-1] != root->node);
2931
2932 lower = path->nodes[level-1];
2933 if (level == 1)
2934 btrfs_item_key(lower, &lower_key, 0);
2935 else
2936 btrfs_node_key(lower, &lower_key, 0);
2937
2938 c = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
2939 root->root_key.objectid, &lower_key,
2940 level, root->node->start, 0);
2941 if (IS_ERR(c))
2942 return PTR_ERR(c);
2943
2944 root_add_used(root, root->nodesize);
2945
2946 memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
2947 btrfs_set_header_nritems(c, 1);
2948 btrfs_set_header_level(c, level);
2949 btrfs_set_header_bytenr(c, c->start);
2950 btrfs_set_header_generation(c, trans->transid);
2951 btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
2952 btrfs_set_header_owner(c, root->root_key.objectid);
2953
2954 write_extent_buffer(c, root->fs_info->fsid,
2955 (unsigned long)btrfs_header_fsid(c),
2956 BTRFS_FSID_SIZE);
2957
2958 write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
2959 (unsigned long)btrfs_header_chunk_tree_uuid(c),
2960 BTRFS_UUID_SIZE);
2961
2962 btrfs_set_node_key(c, &lower_key, 0);
2963 btrfs_set_node_blockptr(c, 0, lower->start);
2964 lower_gen = btrfs_header_generation(lower);
2965 WARN_ON(lower_gen != trans->transid);
2966
2967 btrfs_set_node_ptr_generation(c, 0, lower_gen);
2968
2969 btrfs_mark_buffer_dirty(c);
2970
2971 old = root->node;
2972 tree_mod_log_set_root_pointer(root, c);
2973 rcu_assign_pointer(root->node, c);
2974
2975 /* the super has an extra ref to root->node */
2976 free_extent_buffer(old);
2977
2978 add_root_to_dirty_list(root);
2979 extent_buffer_get(c);
2980 path->nodes[level] = c;
2981 path->locks[level] = BTRFS_WRITE_LOCK;
2982 path->slots[level] = 0;
2983 return 0;
2984}
2985
2986/*
2987 * worker function to insert a single pointer in a node.
2988 * the node should have enough room for the pointer already
2989 *
2990 * slot and level indicate where you want the key to go, and
2991 * blocknr is the block the key points to.
2992 */
2993static void insert_ptr(struct btrfs_trans_handle *trans,
2994 struct btrfs_root *root, struct btrfs_path *path,
2995 struct btrfs_disk_key *key, u64 bytenr,
2996 int slot, int level)
2997{
2998 struct extent_buffer *lower;
2999 int nritems;
3000 int ret;
3001
3002 BUG_ON(!path->nodes[level]);
3003 btrfs_assert_tree_locked(path->nodes[level]);
3004 lower = path->nodes[level];
3005 nritems = btrfs_header_nritems(lower);
3006 BUG_ON(slot > nritems);
3007 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(root));
3008 if (slot != nritems) {
3009 if (level)
3010 tree_mod_log_eb_move(root->fs_info, lower, slot + 1,
3011 slot, nritems - slot);
3012 memmove_extent_buffer(lower,
3013 btrfs_node_key_ptr_offset(slot + 1),
3014 btrfs_node_key_ptr_offset(slot),
3015 (nritems - slot) * sizeof(struct btrfs_key_ptr));
3016 }
3017 if (level) {
3018 ret = tree_mod_log_insert_key(root->fs_info, lower, slot,
3019 MOD_LOG_KEY_ADD);
3020 BUG_ON(ret < 0);
3021 }
3022 btrfs_set_node_key(lower, key, slot);
3023 btrfs_set_node_blockptr(lower, slot, bytenr);
3024 WARN_ON(trans->transid == 0);
3025 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3026 btrfs_set_header_nritems(lower, nritems + 1);
3027 btrfs_mark_buffer_dirty(lower);
3028}
3029
3030/*
3031 * split the node at the specified level in path in two.
3032 * The path is corrected to point to the appropriate node after the split
3033 *
3034 * Before splitting this tries to make some room in the node by pushing
3035 * left and right, if either one works, it returns right away.
3036 *
3037 * returns 0 on success and < 0 on failure
3038 */
3039static noinline int split_node(struct btrfs_trans_handle *trans,
3040 struct btrfs_root *root,
3041 struct btrfs_path *path, int level)
3042{
3043 struct extent_buffer *c;
3044 struct extent_buffer *split;
3045 struct btrfs_disk_key disk_key;
3046 int mid;
3047 int ret;
3048 u32 c_nritems;
3049
3050 c = path->nodes[level];
3051 WARN_ON(btrfs_header_generation(c) != trans->transid);
3052 if (c == root->node) {
3053 /* trying to split the root, lets make a new one */
3054 ret = insert_new_root(trans, root, path, level + 1);
3055 if (ret)
3056 return ret;
3057 } else {
3058 ret = push_nodes_for_insert(trans, root, path, level);
3059 c = path->nodes[level];
3060 if (!ret && btrfs_header_nritems(c) <
3061 BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
3062 return 0;
3063 if (ret < 0)
3064 return ret;
3065 }
3066
3067 c_nritems = btrfs_header_nritems(c);
3068 mid = (c_nritems + 1) / 2;
3069 btrfs_node_key(c, &disk_key, mid);
3070
3071 split = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
3072 root->root_key.objectid,
3073 &disk_key, level, c->start, 0);
3074 if (IS_ERR(split))
3075 return PTR_ERR(split);
3076
3077 root_add_used(root, root->nodesize);
3078
3079 memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header));
3080 btrfs_set_header_level(split, btrfs_header_level(c));
3081 btrfs_set_header_bytenr(split, split->start);
3082 btrfs_set_header_generation(split, trans->transid);
3083 btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
3084 btrfs_set_header_owner(split, root->root_key.objectid);
3085 write_extent_buffer(split, root->fs_info->fsid,
3086 (unsigned long)btrfs_header_fsid(split),
3087 BTRFS_FSID_SIZE);
3088 write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
3089 (unsigned long)btrfs_header_chunk_tree_uuid(split),
3090 BTRFS_UUID_SIZE);
3091
3092 tree_mod_log_eb_copy(root->fs_info, split, c, 0, mid, c_nritems - mid);
3093 copy_extent_buffer(split, c,
3094 btrfs_node_key_ptr_offset(0),
3095 btrfs_node_key_ptr_offset(mid),
3096 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3097 btrfs_set_header_nritems(split, c_nritems - mid);
3098 btrfs_set_header_nritems(c, mid);
3099 ret = 0;
3100
3101 btrfs_mark_buffer_dirty(c);
3102 btrfs_mark_buffer_dirty(split);
3103
3104 insert_ptr(trans, root, path, &disk_key, split->start,
3105 path->slots[level + 1] + 1, level + 1);
3106
3107 if (path->slots[level] >= mid) {
3108 path->slots[level] -= mid;
3109 btrfs_tree_unlock(c);
3110 free_extent_buffer(c);
3111 path->nodes[level] = split;
3112 path->slots[level + 1] += 1;
3113 } else {
3114 btrfs_tree_unlock(split);
3115 free_extent_buffer(split);
3116 }
3117 return ret;
3118}
3119
3120/*
3121 * how many bytes are required to store the items in a leaf. start
3122 * and nr indicate which items in the leaf to check. This totals up the
3123 * space used both by the item structs and the item data
3124 */
3125static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3126{
3127 int data_len;
3128 int nritems = btrfs_header_nritems(l);
3129 int end = min(nritems, start + nr) - 1;
3130
3131 if (!nr)
3132 return 0;
3133 data_len = btrfs_item_end_nr(l, start);
3134 data_len = data_len - btrfs_item_offset_nr(l, end);
3135 data_len += sizeof(struct btrfs_item) * nr;
3136 WARN_ON(data_len < 0);
3137 return data_len;
3138}
3139
3140/*
3141 * The space between the end of the leaf items and
3142 * the start of the leaf data. IOW, how much room
3143 * the leaf has left for both items and data
3144 */
3145noinline int btrfs_leaf_free_space(struct btrfs_root *root,
3146 struct extent_buffer *leaf)
3147{
3148 int nritems = btrfs_header_nritems(leaf);
3149 int ret;
3150 ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
3151 if (ret < 0) {
3152 printk(KERN_CRIT "leaf free space ret %d, leaf data size %lu, "
3153 "used %d nritems %d\n",
3154 ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
3155 leaf_space_used(leaf, 0, nritems), nritems);
3156 }
3157 return ret;
3158}
3159
3160/*
3161 * min slot controls the lowest index we're willing to push to the
3162 * right. We'll push up to and including min_slot, but no lower
3163 */
3164static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
3165 struct btrfs_root *root,
3166 struct btrfs_path *path,
3167 int data_size, int empty,
3168 struct extent_buffer *right,
3169 int free_space, u32 left_nritems,
3170 u32 min_slot)
3171{
3172 struct extent_buffer *left = path->nodes[0];
3173 struct extent_buffer *upper = path->nodes[1];
3174 struct btrfs_map_token token;
3175 struct btrfs_disk_key disk_key;
3176 int slot;
3177 u32 i;
3178 int push_space = 0;
3179 int push_items = 0;
3180 struct btrfs_item *item;
3181 u32 nr;
3182 u32 right_nritems;
3183 u32 data_end;
3184 u32 this_item_size;
3185
3186 btrfs_init_map_token(&token);
3187
3188 if (empty)
3189 nr = 0;
3190 else
3191 nr = max_t(u32, 1, min_slot);
3192
3193 if (path->slots[0] >= left_nritems)
3194 push_space += data_size;
3195
3196 slot = path->slots[1];
3197 i = left_nritems - 1;
3198 while (i >= nr) {
3199 item = btrfs_item_nr(left, i);
3200
3201 if (!empty && push_items > 0) {
3202 if (path->slots[0] > i)
3203 break;
3204 if (path->slots[0] == i) {
3205 int space = btrfs_leaf_free_space(root, left);
3206 if (space + push_space * 2 > free_space)
3207 break;
3208 }
3209 }
3210
3211 if (path->slots[0] == i)
3212 push_space += data_size;
3213
3214 this_item_size = btrfs_item_size(left, item);
3215 if (this_item_size + sizeof(*item) + push_space > free_space)
3216 break;
3217
3218 push_items++;
3219 push_space += this_item_size + sizeof(*item);
3220 if (i == 0)
3221 break;
3222 i--;
3223 }
3224
3225 if (push_items == 0)
3226 goto out_unlock;
3227
3228 if (!empty && push_items == left_nritems)
3229 WARN_ON(1);
3230
3231 /* push left to right */
3232 right_nritems = btrfs_header_nritems(right);
3233
3234 push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3235 push_space -= leaf_data_end(root, left);
3236
3237 /* make room in the right data area */
3238 data_end = leaf_data_end(root, right);
3239 memmove_extent_buffer(right,
3240 btrfs_leaf_data(right) + data_end - push_space,
3241 btrfs_leaf_data(right) + data_end,
3242 BTRFS_LEAF_DATA_SIZE(root) - data_end);
3243
3244 /* copy from the left data area */
3245 copy_extent_buffer(right, left, btrfs_leaf_data(right) +
3246 BTRFS_LEAF_DATA_SIZE(root) - push_space,
3247 btrfs_leaf_data(left) + leaf_data_end(root, left),
3248 push_space);
3249
3250 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3251 btrfs_item_nr_offset(0),
3252 right_nritems * sizeof(struct btrfs_item));
3253
3254 /* copy the items from left to right */
3255 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3256 btrfs_item_nr_offset(left_nritems - push_items),
3257 push_items * sizeof(struct btrfs_item));
3258
3259 /* update the item pointers */
3260 right_nritems += push_items;
3261 btrfs_set_header_nritems(right, right_nritems);
3262 push_space = BTRFS_LEAF_DATA_SIZE(root);
3263 for (i = 0; i < right_nritems; i++) {
3264 item = btrfs_item_nr(right, i);
3265 push_space -= btrfs_token_item_size(right, item, &token);
3266 btrfs_set_token_item_offset(right, item, push_space, &token);
3267 }
3268
3269 left_nritems -= push_items;
3270 btrfs_set_header_nritems(left, left_nritems);
3271
3272 if (left_nritems)
3273 btrfs_mark_buffer_dirty(left);
3274 else
3275 clean_tree_block(trans, root, left);
3276
3277 btrfs_mark_buffer_dirty(right);
3278
3279 btrfs_item_key(right, &disk_key, 0);
3280 btrfs_set_node_key(upper, &disk_key, slot + 1);
3281 btrfs_mark_buffer_dirty(upper);
3282
3283 /* then fixup the leaf pointer in the path */
3284 if (path->slots[0] >= left_nritems) {
3285 path->slots[0] -= left_nritems;
3286 if (btrfs_header_nritems(path->nodes[0]) == 0)
3287 clean_tree_block(trans, root, path->nodes[0]);
3288 btrfs_tree_unlock(path->nodes[0]);
3289 free_extent_buffer(path->nodes[0]);
3290 path->nodes[0] = right;
3291 path->slots[1] += 1;
3292 } else {
3293 btrfs_tree_unlock(right);
3294 free_extent_buffer(right);
3295 }
3296 return 0;
3297
3298out_unlock:
3299 btrfs_tree_unlock(right);
3300 free_extent_buffer(right);
3301 return 1;
3302}
3303
3304/*
3305 * push some data in the path leaf to the right, trying to free up at
3306 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3307 *
3308 * returns 1 if the push failed because the other node didn't have enough
3309 * room, 0 if everything worked out and < 0 if there were major errors.
3310 *
3311 * this will push starting from min_slot to the end of the leaf. It won't
3312 * push any slot lower than min_slot
3313 */
3314static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3315 *root, struct btrfs_path *path,
3316 int min_data_size, int data_size,
3317 int empty, u32 min_slot)
3318{
3319 struct extent_buffer *left = path->nodes[0];
3320 struct extent_buffer *right;
3321 struct extent_buffer *upper;
3322 int slot;
3323 int free_space;
3324 u32 left_nritems;
3325 int ret;
3326
3327 if (!path->nodes[1])
3328 return 1;
3329
3330 slot = path->slots[1];
3331 upper = path->nodes[1];
3332 if (slot >= btrfs_header_nritems(upper) - 1)
3333 return 1;
3334
3335 btrfs_assert_tree_locked(path->nodes[1]);
3336
3337 right = read_node_slot(root, upper, slot + 1);
3338 if (right == NULL)
3339 return 1;
3340
3341 btrfs_tree_lock(right);
3342 btrfs_set_lock_blocking(right);
3343
3344 free_space = btrfs_leaf_free_space(root, right);
3345 if (free_space < data_size)
3346 goto out_unlock;
3347
3348 /* cow and double check */
3349 ret = btrfs_cow_block(trans, root, right, upper,
3350 slot + 1, &right);
3351 if (ret)
3352 goto out_unlock;
3353
3354 free_space = btrfs_leaf_free_space(root, right);
3355 if (free_space < data_size)
3356 goto out_unlock;
3357
3358 left_nritems = btrfs_header_nritems(left);
3359 if (left_nritems == 0)
3360 goto out_unlock;
3361
3362 return __push_leaf_right(trans, root, path, min_data_size, empty,
3363 right, free_space, left_nritems, min_slot);
3364out_unlock:
3365 btrfs_tree_unlock(right);
3366 free_extent_buffer(right);
3367 return 1;
3368}
3369
3370/*
3371 * push some data in the path leaf to the left, trying to free up at
3372 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3373 *
3374 * max_slot can put a limit on how far into the leaf we'll push items. The
3375 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3376 * items
3377 */
3378static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
3379 struct btrfs_root *root,
3380 struct btrfs_path *path, int data_size,
3381 int empty, struct extent_buffer *left,
3382 int free_space, u32 right_nritems,
3383 u32 max_slot)
3384{
3385 struct btrfs_disk_key disk_key;
3386 struct extent_buffer *right = path->nodes[0];
3387 int i;
3388 int push_space = 0;
3389 int push_items = 0;
3390 struct btrfs_item *item;
3391 u32 old_left_nritems;
3392 u32 nr;
3393 int ret = 0;
3394 u32 this_item_size;
3395 u32 old_left_item_size;
3396 struct btrfs_map_token token;
3397
3398 btrfs_init_map_token(&token);
3399
3400 if (empty)
3401 nr = min(right_nritems, max_slot);
3402 else
3403 nr = min(right_nritems - 1, max_slot);
3404
3405 for (i = 0; i < nr; i++) {
3406 item = btrfs_item_nr(right, i);
3407
3408 if (!empty && push_items > 0) {
3409 if (path->slots[0] < i)
3410 break;
3411 if (path->slots[0] == i) {
3412 int space = btrfs_leaf_free_space(root, right);
3413 if (space + push_space * 2 > free_space)
3414 break;
3415 }
3416 }
3417
3418 if (path->slots[0] == i)
3419 push_space += data_size;
3420
3421 this_item_size = btrfs_item_size(right, item);
3422 if (this_item_size + sizeof(*item) + push_space > free_space)
3423 break;
3424
3425 push_items++;
3426 push_space += this_item_size + sizeof(*item);
3427 }
3428
3429 if (push_items == 0) {
3430 ret = 1;
3431 goto out;
3432 }
3433 if (!empty && push_items == btrfs_header_nritems(right))
3434 WARN_ON(1);
3435
3436 /* push data from right to left */
3437 copy_extent_buffer(left, right,
3438 btrfs_item_nr_offset(btrfs_header_nritems(left)),
3439 btrfs_item_nr_offset(0),
3440 push_items * sizeof(struct btrfs_item));
3441
3442 push_space = BTRFS_LEAF_DATA_SIZE(root) -
3443 btrfs_item_offset_nr(right, push_items - 1);
3444
3445 copy_extent_buffer(left, right, btrfs_leaf_data(left) +
3446 leaf_data_end(root, left) - push_space,
3447 btrfs_leaf_data(right) +
3448 btrfs_item_offset_nr(right, push_items - 1),
3449 push_space);
3450 old_left_nritems = btrfs_header_nritems(left);
3451 BUG_ON(old_left_nritems <= 0);
3452
3453 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3454 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3455 u32 ioff;
3456
3457 item = btrfs_item_nr(left, i);
3458
3459 ioff = btrfs_token_item_offset(left, item, &token);
3460 btrfs_set_token_item_offset(left, item,
3461 ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size),
3462 &token);
3463 }
3464 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3465
3466 /* fixup right node */
3467 if (push_items > right_nritems) {
3468 printk(KERN_CRIT "push items %d nr %u\n", push_items,
3469 right_nritems);
3470 WARN_ON(1);
3471 }
3472
3473 if (push_items < right_nritems) {
3474 push_space = btrfs_item_offset_nr(right, push_items - 1) -
3475 leaf_data_end(root, right);
3476 memmove_extent_buffer(right, btrfs_leaf_data(right) +
3477 BTRFS_LEAF_DATA_SIZE(root) - push_space,
3478 btrfs_leaf_data(right) +
3479 leaf_data_end(root, right), push_space);
3480
3481 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3482 btrfs_item_nr_offset(push_items),
3483 (btrfs_header_nritems(right) - push_items) *
3484 sizeof(struct btrfs_item));
3485 }
3486 right_nritems -= push_items;
3487 btrfs_set_header_nritems(right, right_nritems);
3488 push_space = BTRFS_LEAF_DATA_SIZE(root);
3489 for (i = 0; i < right_nritems; i++) {
3490 item = btrfs_item_nr(right, i);
3491
3492 push_space = push_space - btrfs_token_item_size(right,
3493 item, &token);
3494 btrfs_set_token_item_offset(right, item, push_space, &token);
3495 }
3496
3497 btrfs_mark_buffer_dirty(left);
3498 if (right_nritems)
3499 btrfs_mark_buffer_dirty(right);
3500 else
3501 clean_tree_block(trans, root, right);
3502
3503 btrfs_item_key(right, &disk_key, 0);
3504 fixup_low_keys(trans, root, path, &disk_key, 1);
3505
3506 /* then fixup the leaf pointer in the path */
3507 if (path->slots[0] < push_items) {
3508 path->slots[0] += old_left_nritems;
3509 btrfs_tree_unlock(path->nodes[0]);
3510 free_extent_buffer(path->nodes[0]);
3511 path->nodes[0] = left;
3512 path->slots[1] -= 1;
3513 } else {
3514 btrfs_tree_unlock(left);
3515 free_extent_buffer(left);
3516 path->slots[0] -= push_items;
3517 }
3518 BUG_ON(path->slots[0] < 0);
3519 return ret;
3520out:
3521 btrfs_tree_unlock(left);
3522 free_extent_buffer(left);
3523 return ret;
3524}
3525
3526/*
3527 * push some data in the path leaf to the left, trying to free up at
3528 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3529 *
3530 * max_slot can put a limit on how far into the leaf we'll push items. The
3531 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3532 * items
3533 */
3534static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3535 *root, struct btrfs_path *path, int min_data_size,
3536 int data_size, int empty, u32 max_slot)
3537{
3538 struct extent_buffer *right = path->nodes[0];
3539 struct extent_buffer *left;
3540 int slot;
3541 int free_space;
3542 u32 right_nritems;
3543 int ret = 0;
3544
3545 slot = path->slots[1];
3546 if (slot == 0)
3547 return 1;
3548 if (!path->nodes[1])
3549 return 1;
3550
3551 right_nritems = btrfs_header_nritems(right);
3552 if (right_nritems == 0)
3553 return 1;
3554
3555 btrfs_assert_tree_locked(path->nodes[1]);
3556
3557 left = read_node_slot(root, path->nodes[1], slot - 1);
3558 if (left == NULL)
3559 return 1;
3560
3561 btrfs_tree_lock(left);
3562 btrfs_set_lock_blocking(left);
3563
3564 free_space = btrfs_leaf_free_space(root, left);
3565 if (free_space < data_size) {
3566 ret = 1;
3567 goto out;
3568 }
3569
3570 /* cow and double check */
3571 ret = btrfs_cow_block(trans, root, left,
3572 path->nodes[1], slot - 1, &left);
3573 if (ret) {
3574 /* we hit -ENOSPC, but it isn't fatal here */
3575 if (ret == -ENOSPC)
3576 ret = 1;
3577 goto out;
3578 }
3579
3580 free_space = btrfs_leaf_free_space(root, left);
3581 if (free_space < data_size) {
3582 ret = 1;
3583 goto out;
3584 }
3585
3586 return __push_leaf_left(trans, root, path, min_data_size,
3587 empty, left, free_space, right_nritems,
3588 max_slot);
3589out:
3590 btrfs_tree_unlock(left);
3591 free_extent_buffer(left);
3592 return ret;
3593}
3594
3595/*
3596 * split the path's leaf in two, making sure there is at least data_size
3597 * available for the resulting leaf level of the path.
3598 */
3599static noinline void copy_for_split(struct btrfs_trans_handle *trans,
3600 struct btrfs_root *root,
3601 struct btrfs_path *path,
3602 struct extent_buffer *l,
3603 struct extent_buffer *right,
3604 int slot, int mid, int nritems)
3605{
3606 int data_copy_size;
3607 int rt_data_off;
3608 int i;
3609 struct btrfs_disk_key disk_key;
3610 struct btrfs_map_token token;
3611
3612 btrfs_init_map_token(&token);
3613
3614 nritems = nritems - mid;
3615 btrfs_set_header_nritems(right, nritems);
3616 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
3617
3618 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
3619 btrfs_item_nr_offset(mid),
3620 nritems * sizeof(struct btrfs_item));
3621
3622 copy_extent_buffer(right, l,
3623 btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
3624 data_copy_size, btrfs_leaf_data(l) +
3625 leaf_data_end(root, l), data_copy_size);
3626
3627 rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
3628 btrfs_item_end_nr(l, mid);
3629
3630 for (i = 0; i < nritems; i++) {
3631 struct btrfs_item *item = btrfs_item_nr(right, i);
3632 u32 ioff;
3633
3634 ioff = btrfs_token_item_offset(right, item, &token);
3635 btrfs_set_token_item_offset(right, item,
3636 ioff + rt_data_off, &token);
3637 }
3638
3639 btrfs_set_header_nritems(l, mid);
3640 btrfs_item_key(right, &disk_key, 0);
3641 insert_ptr(trans, root, path, &disk_key, right->start,
3642 path->slots[1] + 1, 1);
3643
3644 btrfs_mark_buffer_dirty(right);
3645 btrfs_mark_buffer_dirty(l);
3646 BUG_ON(path->slots[0] != slot);
3647
3648 if (mid <= slot) {
3649 btrfs_tree_unlock(path->nodes[0]);
3650 free_extent_buffer(path->nodes[0]);
3651 path->nodes[0] = right;
3652 path->slots[0] -= mid;
3653 path->slots[1] += 1;
3654 } else {
3655 btrfs_tree_unlock(right);
3656 free_extent_buffer(right);
3657 }
3658
3659 BUG_ON(path->slots[0] < 0);
3660}
3661
3662/*
3663 * double splits happen when we need to insert a big item in the middle
3664 * of a leaf. A double split can leave us with 3 mostly empty leaves:
3665 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
3666 * A B C
3667 *
3668 * We avoid this by trying to push the items on either side of our target
3669 * into the adjacent leaves. If all goes well we can avoid the double split
3670 * completely.
3671 */
3672static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
3673 struct btrfs_root *root,
3674 struct btrfs_path *path,
3675 int data_size)
3676{
3677 int ret;
3678 int progress = 0;
3679 int slot;
3680 u32 nritems;
3681
3682 slot = path->slots[0];
3683
3684 /*
3685 * try to push all the items after our slot into the
3686 * right leaf
3687 */
3688 ret = push_leaf_right(trans, root, path, 1, data_size, 0, slot);
3689 if (ret < 0)
3690 return ret;
3691
3692 if (ret == 0)
3693 progress++;
3694
3695 nritems = btrfs_header_nritems(path->nodes[0]);
3696 /*
3697 * our goal is to get our slot at the start or end of a leaf. If
3698 * we've done so we're done
3699 */
3700 if (path->slots[0] == 0 || path->slots[0] == nritems)
3701 return 0;
3702
3703 if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
3704 return 0;
3705
3706 /* try to push all the items before our slot into the next leaf */
3707 slot = path->slots[0];
3708 ret = push_leaf_left(trans, root, path, 1, data_size, 0, slot);
3709 if (ret < 0)
3710 return ret;
3711
3712 if (ret == 0)
3713 progress++;
3714
3715 if (progress)
3716 return 0;
3717 return 1;
3718}
3719
3720/*
3721 * split the path's leaf in two, making sure there is at least data_size
3722 * available for the resulting leaf level of the path.
3723 *
3724 * returns 0 if all went well and < 0 on failure.
3725 */
3726static noinline int split_leaf(struct btrfs_trans_handle *trans,
3727 struct btrfs_root *root,
3728 struct btrfs_key *ins_key,
3729 struct btrfs_path *path, int data_size,
3730 int extend)
3731{
3732 struct btrfs_disk_key disk_key;
3733 struct extent_buffer *l;
3734 u32 nritems;
3735 int mid;
3736 int slot;
3737 struct extent_buffer *right;
3738 int ret = 0;
3739 int wret;
3740 int split;
3741 int num_doubles = 0;
3742 int tried_avoid_double = 0;
3743
3744 l = path->nodes[0];
3745 slot = path->slots[0];
3746 if (extend && data_size + btrfs_item_size_nr(l, slot) +
3747 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root))
3748 return -EOVERFLOW;
3749
3750 /* first try to make some room by pushing left and right */
3751 if (data_size) {
3752 wret = push_leaf_right(trans, root, path, data_size,
3753 data_size, 0, 0);
3754 if (wret < 0)
3755 return wret;
3756 if (wret) {
3757 wret = push_leaf_left(trans, root, path, data_size,
3758 data_size, 0, (u32)-1);
3759 if (wret < 0)
3760 return wret;
3761 }
3762 l = path->nodes[0];
3763
3764 /* did the pushes work? */
3765 if (btrfs_leaf_free_space(root, l) >= data_size)
3766 return 0;
3767 }
3768
3769 if (!path->nodes[1]) {
3770 ret = insert_new_root(trans, root, path, 1);
3771 if (ret)
3772 return ret;
3773 }
3774again:
3775 split = 1;
3776 l = path->nodes[0];
3777 slot = path->slots[0];
3778 nritems = btrfs_header_nritems(l);
3779 mid = (nritems + 1) / 2;
3780
3781 if (mid <= slot) {
3782 if (nritems == 1 ||
3783 leaf_space_used(l, mid, nritems - mid) + data_size >
3784 BTRFS_LEAF_DATA_SIZE(root)) {
3785 if (slot >= nritems) {
3786 split = 0;
3787 } else {
3788 mid = slot;
3789 if (mid != nritems &&
3790 leaf_space_used(l, mid, nritems - mid) +
3791 data_size > BTRFS_LEAF_DATA_SIZE(root)) {
3792 if (data_size && !tried_avoid_double)
3793 goto push_for_double;
3794 split = 2;
3795 }
3796 }
3797 }
3798 } else {
3799 if (leaf_space_used(l, 0, mid) + data_size >
3800 BTRFS_LEAF_DATA_SIZE(root)) {
3801 if (!extend && data_size && slot == 0) {
3802 split = 0;
3803 } else if ((extend || !data_size) && slot == 0) {
3804 mid = 1;
3805 } else {
3806 mid = slot;
3807 if (mid != nritems &&
3808 leaf_space_used(l, mid, nritems - mid) +
3809 data_size > BTRFS_LEAF_DATA_SIZE(root)) {
3810 if (data_size && !tried_avoid_double)
3811 goto push_for_double;
3812 split = 2 ;
3813 }
3814 }
3815 }
3816 }
3817
3818 if (split == 0)
3819 btrfs_cpu_key_to_disk(&disk_key, ins_key);
3820 else
3821 btrfs_item_key(l, &disk_key, mid);
3822
3823 right = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
3824 root->root_key.objectid,
3825 &disk_key, 0, l->start, 0);
3826 if (IS_ERR(right))
3827 return PTR_ERR(right);
3828
3829 root_add_used(root, root->leafsize);
3830
3831 memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
3832 btrfs_set_header_bytenr(right, right->start);
3833 btrfs_set_header_generation(right, trans->transid);
3834 btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
3835 btrfs_set_header_owner(right, root->root_key.objectid);
3836 btrfs_set_header_level(right, 0);
3837 write_extent_buffer(right, root->fs_info->fsid,
3838 (unsigned long)btrfs_header_fsid(right),
3839 BTRFS_FSID_SIZE);
3840
3841 write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
3842 (unsigned long)btrfs_header_chunk_tree_uuid(right),
3843 BTRFS_UUID_SIZE);
3844
3845 if (split == 0) {
3846 if (mid <= slot) {
3847 btrfs_set_header_nritems(right, 0);
3848 insert_ptr(trans, root, path, &disk_key, right->start,
3849 path->slots[1] + 1, 1);
3850 btrfs_tree_unlock(path->nodes[0]);
3851 free_extent_buffer(path->nodes[0]);
3852 path->nodes[0] = right;
3853 path->slots[0] = 0;
3854 path->slots[1] += 1;
3855 } else {
3856 btrfs_set_header_nritems(right, 0);
3857 insert_ptr(trans, root, path, &disk_key, right->start,
3858 path->slots[1], 1);
3859 btrfs_tree_unlock(path->nodes[0]);
3860 free_extent_buffer(path->nodes[0]);
3861 path->nodes[0] = right;
3862 path->slots[0] = 0;
3863 if (path->slots[1] == 0)
3864 fixup_low_keys(trans, root, path,
3865 &disk_key, 1);
3866 }
3867 btrfs_mark_buffer_dirty(right);
3868 return ret;
3869 }
3870
3871 copy_for_split(trans, root, path, l, right, slot, mid, nritems);
3872
3873 if (split == 2) {
3874 BUG_ON(num_doubles != 0);
3875 num_doubles++;
3876 goto again;
3877 }
3878
3879 return 0;
3880
3881push_for_double:
3882 push_for_double_split(trans, root, path, data_size);
3883 tried_avoid_double = 1;
3884 if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
3885 return 0;
3886 goto again;
3887}
3888
3889static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3890 struct btrfs_root *root,
3891 struct btrfs_path *path, int ins_len)
3892{
3893 struct btrfs_key key;
3894 struct extent_buffer *leaf;
3895 struct btrfs_file_extent_item *fi;
3896 u64 extent_len = 0;
3897 u32 item_size;
3898 int ret;
3899
3900 leaf = path->nodes[0];
3901 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3902
3903 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3904 key.type != BTRFS_EXTENT_CSUM_KEY);
3905
3906 if (btrfs_leaf_free_space(root, leaf) >= ins_len)
3907 return 0;
3908
3909 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3910 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3911 fi = btrfs_item_ptr(leaf, path->slots[0],
3912 struct btrfs_file_extent_item);
3913 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3914 }
3915 btrfs_release_path(path);
3916
3917 path->keep_locks = 1;
3918 path->search_for_split = 1;
3919 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3920 path->search_for_split = 0;
3921 if (ret < 0)
3922 goto err;
3923
3924 ret = -EAGAIN;
3925 leaf = path->nodes[0];
3926 /* if our item isn't there or got smaller, return now */
3927 if (ret > 0 || item_size != btrfs_item_size_nr(leaf, path->slots[0]))
3928 goto err;
3929
3930 /* the leaf has changed, it now has room. return now */
3931 if (btrfs_leaf_free_space(root, path->nodes[0]) >= ins_len)
3932 goto err;
3933
3934 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3935 fi = btrfs_item_ptr(leaf, path->slots[0],
3936 struct btrfs_file_extent_item);
3937 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3938 goto err;
3939 }
3940
3941 btrfs_set_path_blocking(path);
3942 ret = split_leaf(trans, root, &key, path, ins_len, 1);
3943 if (ret)
3944 goto err;
3945
3946 path->keep_locks = 0;
3947 btrfs_unlock_up_safe(path, 1);
3948 return 0;
3949err:
3950 path->keep_locks = 0;
3951 return ret;
3952}
3953
3954static noinline int split_item(struct btrfs_trans_handle *trans,
3955 struct btrfs_root *root,
3956 struct btrfs_path *path,
3957 struct btrfs_key *new_key,
3958 unsigned long split_offset)
3959{
3960 struct extent_buffer *leaf;
3961 struct btrfs_item *item;
3962 struct btrfs_item *new_item;
3963 int slot;
3964 char *buf;
3965 u32 nritems;
3966 u32 item_size;
3967 u32 orig_offset;
3968 struct btrfs_disk_key disk_key;
3969
3970 leaf = path->nodes[0];
3971 BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
3972
3973 btrfs_set_path_blocking(path);
3974
3975 item = btrfs_item_nr(leaf, path->slots[0]);
3976 orig_offset = btrfs_item_offset(leaf, item);
3977 item_size = btrfs_item_size(leaf, item);
3978
3979 buf = kmalloc(item_size, GFP_NOFS);
3980 if (!buf)
3981 return -ENOMEM;
3982
3983 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3984 path->slots[0]), item_size);
3985
3986 slot = path->slots[0] + 1;
3987 nritems = btrfs_header_nritems(leaf);
3988 if (slot != nritems) {
3989 /* shift the items */
3990 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
3991 btrfs_item_nr_offset(slot),
3992 (nritems - slot) * sizeof(struct btrfs_item));
3993 }
3994
3995 btrfs_cpu_key_to_disk(&disk_key, new_key);
3996 btrfs_set_item_key(leaf, &disk_key, slot);
3997
3998 new_item = btrfs_item_nr(leaf, slot);
3999
4000 btrfs_set_item_offset(leaf, new_item, orig_offset);
4001 btrfs_set_item_size(leaf, new_item, item_size - split_offset);
4002
4003 btrfs_set_item_offset(leaf, item,
4004 orig_offset + item_size - split_offset);
4005 btrfs_set_item_size(leaf, item, split_offset);
4006
4007 btrfs_set_header_nritems(leaf, nritems + 1);
4008
4009 /* write the data for the start of the original item */
4010 write_extent_buffer(leaf, buf,
4011 btrfs_item_ptr_offset(leaf, path->slots[0]),
4012 split_offset);
4013
4014 /* write the data for the new item */
4015 write_extent_buffer(leaf, buf + split_offset,
4016 btrfs_item_ptr_offset(leaf, slot),
4017 item_size - split_offset);
4018 btrfs_mark_buffer_dirty(leaf);
4019
4020 BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
4021 kfree(buf);
4022 return 0;
4023}
4024
4025/*
4026 * This function splits a single item into two items,
4027 * giving 'new_key' to the new item and splitting the
4028 * old one at split_offset (from the start of the item).
4029 *
4030 * The path may be released by this operation. After
4031 * the split, the path is pointing to the old item. The
4032 * new item is going to be in the same node as the old one.
4033 *
4034 * Note, the item being split must be smaller enough to live alone on
4035 * a tree block with room for one extra struct btrfs_item
4036 *
4037 * This allows us to split the item in place, keeping a lock on the
4038 * leaf the entire time.
4039 */
4040int btrfs_split_item(struct btrfs_trans_handle *trans,
4041 struct btrfs_root *root,
4042 struct btrfs_path *path,
4043 struct btrfs_key *new_key,
4044 unsigned long split_offset)
4045{
4046 int ret;
4047 ret = setup_leaf_for_split(trans, root, path,
4048 sizeof(struct btrfs_item));
4049 if (ret)
4050 return ret;
4051
4052 ret = split_item(trans, root, path, new_key, split_offset);
4053 return ret;
4054}
4055
4056/*
4057 * This function duplicate a item, giving 'new_key' to the new item.
4058 * It guarantees both items live in the same tree leaf and the new item
4059 * is contiguous with the original item.
4060 *
4061 * This allows us to split file extent in place, keeping a lock on the
4062 * leaf the entire time.
4063 */
4064int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4065 struct btrfs_root *root,
4066 struct btrfs_path *path,
4067 struct btrfs_key *new_key)
4068{
4069 struct extent_buffer *leaf;
4070 int ret;
4071 u32 item_size;
4072
4073 leaf = path->nodes[0];
4074 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4075 ret = setup_leaf_for_split(trans, root, path,
4076 item_size + sizeof(struct btrfs_item));
4077 if (ret)
4078 return ret;
4079
4080 path->slots[0]++;
4081 setup_items_for_insert(trans, root, path, new_key, &item_size,
4082 item_size, item_size +
4083 sizeof(struct btrfs_item), 1);
4084 leaf = path->nodes[0];
4085 memcpy_extent_buffer(leaf,
4086 btrfs_item_ptr_offset(leaf, path->slots[0]),
4087 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4088 item_size);
4089 return 0;
4090}
4091
4092/*
4093 * make the item pointed to by the path smaller. new_size indicates
4094 * how small to make it, and from_end tells us if we just chop bytes
4095 * off the end of the item or if we shift the item to chop bytes off
4096 * the front.
4097 */
4098void btrfs_truncate_item(struct btrfs_trans_handle *trans,
4099 struct btrfs_root *root,
4100 struct btrfs_path *path,
4101 u32 new_size, int from_end)
4102{
4103 int slot;
4104 struct extent_buffer *leaf;
4105 struct btrfs_item *item;
4106 u32 nritems;
4107 unsigned int data_end;
4108 unsigned int old_data_start;
4109 unsigned int old_size;
4110 unsigned int size_diff;
4111 int i;
4112 struct btrfs_map_token token;
4113
4114 btrfs_init_map_token(&token);
4115
4116 leaf = path->nodes[0];
4117 slot = path->slots[0];
4118
4119 old_size = btrfs_item_size_nr(leaf, slot);
4120 if (old_size == new_size)
4121 return;
4122
4123 nritems = btrfs_header_nritems(leaf);
4124 data_end = leaf_data_end(root, leaf);
4125
4126 old_data_start = btrfs_item_offset_nr(leaf, slot);
4127
4128 size_diff = old_size - new_size;
4129
4130 BUG_ON(slot < 0);
4131 BUG_ON(slot >= nritems);
4132
4133 /*
4134 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4135 */
4136 /* first correct the data pointers */
4137 for (i = slot; i < nritems; i++) {
4138 u32 ioff;
4139 item = btrfs_item_nr(leaf, i);
4140
4141 ioff = btrfs_token_item_offset(leaf, item, &token);
4142 btrfs_set_token_item_offset(leaf, item,
4143 ioff + size_diff, &token);
4144 }
4145
4146 /* shift the data */
4147 if (from_end) {
4148 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4149 data_end + size_diff, btrfs_leaf_data(leaf) +
4150 data_end, old_data_start + new_size - data_end);
4151 } else {
4152 struct btrfs_disk_key disk_key;
4153 u64 offset;
4154
4155 btrfs_item_key(leaf, &disk_key, slot);
4156
4157 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4158 unsigned long ptr;
4159 struct btrfs_file_extent_item *fi;
4160
4161 fi = btrfs_item_ptr(leaf, slot,
4162 struct btrfs_file_extent_item);
4163 fi = (struct btrfs_file_extent_item *)(
4164 (unsigned long)fi - size_diff);
4165
4166 if (btrfs_file_extent_type(leaf, fi) ==
4167 BTRFS_FILE_EXTENT_INLINE) {
4168 ptr = btrfs_item_ptr_offset(leaf, slot);
4169 memmove_extent_buffer(leaf, ptr,
4170 (unsigned long)fi,
4171 offsetof(struct btrfs_file_extent_item,
4172 disk_bytenr));
4173 }
4174 }
4175
4176 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4177 data_end + size_diff, btrfs_leaf_data(leaf) +
4178 data_end, old_data_start - data_end);
4179
4180 offset = btrfs_disk_key_offset(&disk_key);
4181 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4182 btrfs_set_item_key(leaf, &disk_key, slot);
4183 if (slot == 0)
4184 fixup_low_keys(trans, root, path, &disk_key, 1);
4185 }
4186
4187 item = btrfs_item_nr(leaf, slot);
4188 btrfs_set_item_size(leaf, item, new_size);
4189 btrfs_mark_buffer_dirty(leaf);
4190
4191 if (btrfs_leaf_free_space(root, leaf) < 0) {
4192 btrfs_print_leaf(root, leaf);
4193 BUG();
4194 }
4195}
4196
4197/*
4198 * make the item pointed to by the path bigger, data_size is the new size.
4199 */
4200void btrfs_extend_item(struct btrfs_trans_handle *trans,
4201 struct btrfs_root *root, struct btrfs_path *path,
4202 u32 data_size)
4203{
4204 int slot;
4205 struct extent_buffer *leaf;
4206 struct btrfs_item *item;
4207 u32 nritems;
4208 unsigned int data_end;
4209 unsigned int old_data;
4210 unsigned int old_size;
4211 int i;
4212 struct btrfs_map_token token;
4213
4214 btrfs_init_map_token(&token);
4215
4216 leaf = path->nodes[0];
4217
4218 nritems = btrfs_header_nritems(leaf);
4219 data_end = leaf_data_end(root, leaf);
4220
4221 if (btrfs_leaf_free_space(root, leaf) < data_size) {
4222 btrfs_print_leaf(root, leaf);
4223 BUG();
4224 }
4225 slot = path->slots[0];
4226 old_data = btrfs_item_end_nr(leaf, slot);
4227
4228 BUG_ON(slot < 0);
4229 if (slot >= nritems) {
4230 btrfs_print_leaf(root, leaf);
4231 printk(KERN_CRIT "slot %d too large, nritems %d\n",
4232 slot, nritems);
4233 BUG_ON(1);
4234 }
4235
4236 /*
4237 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4238 */
4239 /* first correct the data pointers */
4240 for (i = slot; i < nritems; i++) {
4241 u32 ioff;
4242 item = btrfs_item_nr(leaf, i);
4243
4244 ioff = btrfs_token_item_offset(leaf, item, &token);
4245 btrfs_set_token_item_offset(leaf, item,
4246 ioff - data_size, &token);
4247 }
4248
4249 /* shift the data */
4250 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4251 data_end - data_size, btrfs_leaf_data(leaf) +
4252 data_end, old_data - data_end);
4253
4254 data_end = old_data;
4255 old_size = btrfs_item_size_nr(leaf, slot);
4256 item = btrfs_item_nr(leaf, slot);
4257 btrfs_set_item_size(leaf, item, old_size + data_size);
4258 btrfs_mark_buffer_dirty(leaf);
4259
4260 if (btrfs_leaf_free_space(root, leaf) < 0) {
4261 btrfs_print_leaf(root, leaf);
4262 BUG();
4263 }
4264}
4265
4266/*
4267 * Given a key and some data, insert items into the tree.
4268 * This does all the path init required, making room in the tree if needed.
4269 * Returns the number of keys that were inserted.
4270 */
4271int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
4272 struct btrfs_root *root,
4273 struct btrfs_path *path,
4274 struct btrfs_key *cpu_key, u32 *data_size,
4275 int nr)
4276{
4277 struct extent_buffer *leaf;
4278 struct btrfs_item *item;
4279 int ret = 0;
4280 int slot;
4281 int i;
4282 u32 nritems;
4283 u32 total_data = 0;
4284 u32 total_size = 0;
4285 unsigned int data_end;
4286 struct btrfs_disk_key disk_key;
4287 struct btrfs_key found_key;
4288 struct btrfs_map_token token;
4289
4290 btrfs_init_map_token(&token);
4291
4292 for (i = 0; i < nr; i++) {
4293 if (total_size + data_size[i] + sizeof(struct btrfs_item) >
4294 BTRFS_LEAF_DATA_SIZE(root)) {
4295 break;
4296 nr = i;
4297 }
4298 total_data += data_size[i];
4299 total_size += data_size[i] + sizeof(struct btrfs_item);
4300 }
4301 BUG_ON(nr == 0);
4302
4303 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4304 if (ret == 0)
4305 return -EEXIST;
4306 if (ret < 0)
4307 goto out;
4308
4309 leaf = path->nodes[0];
4310
4311 nritems = btrfs_header_nritems(leaf);
4312 data_end = leaf_data_end(root, leaf);
4313
4314 if (btrfs_leaf_free_space(root, leaf) < total_size) {
4315 for (i = nr; i >= 0; i--) {
4316 total_data -= data_size[i];
4317 total_size -= data_size[i] + sizeof(struct btrfs_item);
4318 if (total_size < btrfs_leaf_free_space(root, leaf))
4319 break;
4320 }
4321 nr = i;
4322 }
4323
4324 slot = path->slots[0];
4325 BUG_ON(slot < 0);
4326
4327 if (slot != nritems) {
4328 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4329
4330 item = btrfs_item_nr(leaf, slot);
4331 btrfs_item_key_to_cpu(leaf, &found_key, slot);
4332
4333 /* figure out how many keys we can insert in here */
4334 total_data = data_size[0];
4335 for (i = 1; i < nr; i++) {
4336 if (btrfs_comp_cpu_keys(&found_key, cpu_key + i) <= 0)
4337 break;
4338 total_data += data_size[i];
4339 }
4340 nr = i;
4341
4342 if (old_data < data_end) {
4343 btrfs_print_leaf(root, leaf);
4344 printk(KERN_CRIT "slot %d old_data %d data_end %d\n",
4345 slot, old_data, data_end);
4346 BUG_ON(1);
4347 }
4348 /*
4349 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4350 */
4351 /* first correct the data pointers */
4352 for (i = slot; i < nritems; i++) {
4353 u32 ioff;
4354
4355 item = btrfs_item_nr(leaf, i);
4356 ioff = btrfs_token_item_offset(leaf, item, &token);
4357 btrfs_set_token_item_offset(leaf, item,
4358 ioff - total_data, &token);
4359 }
4360 /* shift the items */
4361 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4362 btrfs_item_nr_offset(slot),
4363 (nritems - slot) * sizeof(struct btrfs_item));
4364
4365 /* shift the data */
4366 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4367 data_end - total_data, btrfs_leaf_data(leaf) +
4368 data_end, old_data - data_end);
4369 data_end = old_data;
4370 } else {
4371 /*
4372 * this sucks but it has to be done, if we are inserting at
4373 * the end of the leaf only insert 1 of the items, since we
4374 * have no way of knowing whats on the next leaf and we'd have
4375 * to drop our current locks to figure it out
4376 */
4377 nr = 1;
4378 }
4379
4380 /* setup the item for the new data */
4381 for (i = 0; i < nr; i++) {
4382 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4383 btrfs_set_item_key(leaf, &disk_key, slot + i);
4384 item = btrfs_item_nr(leaf, slot + i);
4385 btrfs_set_token_item_offset(leaf, item,
4386 data_end - data_size[i], &token);
4387 data_end -= data_size[i];
4388 btrfs_set_token_item_size(leaf, item, data_size[i], &token);
4389 }
4390 btrfs_set_header_nritems(leaf, nritems + nr);
4391 btrfs_mark_buffer_dirty(leaf);
4392
4393 ret = 0;
4394 if (slot == 0) {
4395 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4396 fixup_low_keys(trans, root, path, &disk_key, 1);
4397 }
4398
4399 if (btrfs_leaf_free_space(root, leaf) < 0) {
4400 btrfs_print_leaf(root, leaf);
4401 BUG();
4402 }
4403out:
4404 if (!ret)
4405 ret = nr;
4406 return ret;
4407}
4408
4409/*
4410 * this is a helper for btrfs_insert_empty_items, the main goal here is
4411 * to save stack depth by doing the bulk of the work in a function
4412 * that doesn't call btrfs_search_slot
4413 */
4414void setup_items_for_insert(struct btrfs_trans_handle *trans,
4415 struct btrfs_root *root, struct btrfs_path *path,
4416 struct btrfs_key *cpu_key, u32 *data_size,
4417 u32 total_data, u32 total_size, int nr)
4418{
4419 struct btrfs_item *item;
4420 int i;
4421 u32 nritems;
4422 unsigned int data_end;
4423 struct btrfs_disk_key disk_key;
4424 struct extent_buffer *leaf;
4425 int slot;
4426 struct btrfs_map_token token;
4427
4428 btrfs_init_map_token(&token);
4429
4430 leaf = path->nodes[0];
4431 slot = path->slots[0];
4432
4433 nritems = btrfs_header_nritems(leaf);
4434 data_end = leaf_data_end(root, leaf);
4435
4436 if (btrfs_leaf_free_space(root, leaf) < total_size) {
4437 btrfs_print_leaf(root, leaf);
4438 printk(KERN_CRIT "not enough freespace need %u have %d\n",
4439 total_size, btrfs_leaf_free_space(root, leaf));
4440 BUG();
4441 }
4442
4443 if (slot != nritems) {
4444 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4445
4446 if (old_data < data_end) {
4447 btrfs_print_leaf(root, leaf);
4448 printk(KERN_CRIT "slot %d old_data %d data_end %d\n",
4449 slot, old_data, data_end);
4450 BUG_ON(1);
4451 }
4452 /*
4453 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4454 */
4455 /* first correct the data pointers */
4456 for (i = slot; i < nritems; i++) {
4457 u32 ioff;
4458
4459 item = btrfs_item_nr(leaf, i);
4460 ioff = btrfs_token_item_offset(leaf, item, &token);
4461 btrfs_set_token_item_offset(leaf, item,
4462 ioff - total_data, &token);
4463 }
4464 /* shift the items */
4465 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4466 btrfs_item_nr_offset(slot),
4467 (nritems - slot) * sizeof(struct btrfs_item));
4468
4469 /* shift the data */
4470 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4471 data_end - total_data, btrfs_leaf_data(leaf) +
4472 data_end, old_data - data_end);
4473 data_end = old_data;
4474 }
4475
4476 /* setup the item for the new data */
4477 for (i = 0; i < nr; i++) {
4478 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4479 btrfs_set_item_key(leaf, &disk_key, slot + i);
4480 item = btrfs_item_nr(leaf, slot + i);
4481 btrfs_set_token_item_offset(leaf, item,
4482 data_end - data_size[i], &token);
4483 data_end -= data_size[i];
4484 btrfs_set_token_item_size(leaf, item, data_size[i], &token);
4485 }
4486
4487 btrfs_set_header_nritems(leaf, nritems + nr);
4488
4489 if (slot == 0) {
4490 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4491 fixup_low_keys(trans, root, path, &disk_key, 1);
4492 }
4493 btrfs_unlock_up_safe(path, 1);
4494 btrfs_mark_buffer_dirty(leaf);
4495
4496 if (btrfs_leaf_free_space(root, leaf) < 0) {
4497 btrfs_print_leaf(root, leaf);
4498 BUG();
4499 }
4500}
4501
4502/*
4503 * Given a key and some data, insert items into the tree.
4504 * This does all the path init required, making room in the tree if needed.
4505 */
4506int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4507 struct btrfs_root *root,
4508 struct btrfs_path *path,
4509 struct btrfs_key *cpu_key, u32 *data_size,
4510 int nr)
4511{
4512 int ret = 0;
4513 int slot;
4514 int i;
4515 u32 total_size = 0;
4516 u32 total_data = 0;
4517
4518 for (i = 0; i < nr; i++)
4519 total_data += data_size[i];
4520
4521 total_size = total_data + (nr * sizeof(struct btrfs_item));
4522 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4523 if (ret == 0)
4524 return -EEXIST;
4525 if (ret < 0)
4526 return ret;
4527
4528 slot = path->slots[0];
4529 BUG_ON(slot < 0);
4530
4531 setup_items_for_insert(trans, root, path, cpu_key, data_size,
4532 total_data, total_size, nr);
4533 return 0;
4534}
4535
4536/*
4537 * Given a key and some data, insert an item into the tree.
4538 * This does all the path init required, making room in the tree if needed.
4539 */
4540int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
4541 *root, struct btrfs_key *cpu_key, void *data, u32
4542 data_size)
4543{
4544 int ret = 0;
4545 struct btrfs_path *path;
4546 struct extent_buffer *leaf;
4547 unsigned long ptr;
4548
4549 path = btrfs_alloc_path();
4550 if (!path)
4551 return -ENOMEM;
4552 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4553 if (!ret) {
4554 leaf = path->nodes[0];
4555 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4556 write_extent_buffer(leaf, data, ptr, data_size);
4557 btrfs_mark_buffer_dirty(leaf);
4558 }
4559 btrfs_free_path(path);
4560 return ret;
4561}
4562
4563/*
4564 * delete the pointer from a given node.
4565 *
4566 * the tree should have been previously balanced so the deletion does not
4567 * empty a node.
4568 */
4569static void del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4570 struct btrfs_path *path, int level, int slot,
4571 int tree_mod_log)
4572{
4573 struct extent_buffer *parent = path->nodes[level];
4574 u32 nritems;
4575 int ret;
4576
4577 nritems = btrfs_header_nritems(parent);
4578 if (slot != nritems - 1) {
4579 if (tree_mod_log && level)
4580 tree_mod_log_eb_move(root->fs_info, parent, slot,
4581 slot + 1, nritems - slot - 1);
4582 memmove_extent_buffer(parent,
4583 btrfs_node_key_ptr_offset(slot),
4584 btrfs_node_key_ptr_offset(slot + 1),
4585 sizeof(struct btrfs_key_ptr) *
4586 (nritems - slot - 1));
4587 } else if (tree_mod_log && level) {
4588 ret = tree_mod_log_insert_key(root->fs_info, parent, slot,
4589 MOD_LOG_KEY_REMOVE);
4590 BUG_ON(ret < 0);
4591 }
4592
4593 nritems--;
4594 btrfs_set_header_nritems(parent, nritems);
4595 if (nritems == 0 && parent == root->node) {
4596 BUG_ON(btrfs_header_level(root->node) != 1);
4597 /* just turn the root into a leaf and break */
4598 btrfs_set_header_level(root->node, 0);
4599 } else if (slot == 0) {
4600 struct btrfs_disk_key disk_key;
4601
4602 btrfs_node_key(parent, &disk_key, 0);
4603 fixup_low_keys(trans, root, path, &disk_key, level + 1);
4604 }
4605 btrfs_mark_buffer_dirty(parent);
4606}
4607
4608/*
4609 * a helper function to delete the leaf pointed to by path->slots[1] and
4610 * path->nodes[1].
4611 *
4612 * This deletes the pointer in path->nodes[1] and frees the leaf
4613 * block extent. zero is returned if it all worked out, < 0 otherwise.
4614 *
4615 * The path must have already been setup for deleting the leaf, including
4616 * all the proper balancing. path->nodes[1] must be locked.
4617 */
4618static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4619 struct btrfs_root *root,
4620 struct btrfs_path *path,
4621 struct extent_buffer *leaf)
4622{
4623 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4624 del_ptr(trans, root, path, 1, path->slots[1], 1);
4625
4626 /*
4627 * btrfs_free_extent is expensive, we want to make sure we
4628 * aren't holding any locks when we call it
4629 */
4630 btrfs_unlock_up_safe(path, 0);
4631
4632 root_sub_used(root, leaf->len);
4633
4634 extent_buffer_get(leaf);
4635 btrfs_free_tree_block(trans, root, leaf, 0, 1);
4636 free_extent_buffer_stale(leaf);
4637}
4638/*
4639 * delete the item at the leaf level in path. If that empties
4640 * the leaf, remove it from the tree
4641 */
4642int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4643 struct btrfs_path *path, int slot, int nr)
4644{
4645 struct extent_buffer *leaf;
4646 struct btrfs_item *item;
4647 int last_off;
4648 int dsize = 0;
4649 int ret = 0;
4650 int wret;
4651 int i;
4652 u32 nritems;
4653 struct btrfs_map_token token;
4654
4655 btrfs_init_map_token(&token);
4656
4657 leaf = path->nodes[0];
4658 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4659
4660 for (i = 0; i < nr; i++)
4661 dsize += btrfs_item_size_nr(leaf, slot + i);
4662
4663 nritems = btrfs_header_nritems(leaf);
4664
4665 if (slot + nr != nritems) {
4666 int data_end = leaf_data_end(root, leaf);
4667
4668 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4669 data_end + dsize,
4670 btrfs_leaf_data(leaf) + data_end,
4671 last_off - data_end);
4672
4673 for (i = slot + nr; i < nritems; i++) {
4674 u32 ioff;
4675
4676 item = btrfs_item_nr(leaf, i);
4677 ioff = btrfs_token_item_offset(leaf, item, &token);
4678 btrfs_set_token_item_offset(leaf, item,
4679 ioff + dsize, &token);
4680 }
4681
4682 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
4683 btrfs_item_nr_offset(slot + nr),
4684 sizeof(struct btrfs_item) *
4685 (nritems - slot - nr));
4686 }
4687 btrfs_set_header_nritems(leaf, nritems - nr);
4688 nritems -= nr;
4689
4690 /* delete the leaf if we've emptied it */
4691 if (nritems == 0) {
4692 if (leaf == root->node) {
4693 btrfs_set_header_level(leaf, 0);
4694 } else {
4695 btrfs_set_path_blocking(path);
4696 clean_tree_block(trans, root, leaf);
4697 btrfs_del_leaf(trans, root, path, leaf);
4698 }
4699 } else {
4700 int used = leaf_space_used(leaf, 0, nritems);
4701 if (slot == 0) {
4702 struct btrfs_disk_key disk_key;
4703
4704 btrfs_item_key(leaf, &disk_key, 0);
4705 fixup_low_keys(trans, root, path, &disk_key, 1);
4706 }
4707
4708 /* delete the leaf if it is mostly empty */
4709 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
4710 /* push_leaf_left fixes the path.
4711 * make sure the path still points to our leaf
4712 * for possible call to del_ptr below
4713 */
4714 slot = path->slots[1];
4715 extent_buffer_get(leaf);
4716
4717 btrfs_set_path_blocking(path);
4718 wret = push_leaf_left(trans, root, path, 1, 1,
4719 1, (u32)-1);
4720 if (wret < 0 && wret != -ENOSPC)
4721 ret = wret;
4722
4723 if (path->nodes[0] == leaf &&
4724 btrfs_header_nritems(leaf)) {
4725 wret = push_leaf_right(trans, root, path, 1,
4726 1, 1, 0);
4727 if (wret < 0 && wret != -ENOSPC)
4728 ret = wret;
4729 }
4730
4731 if (btrfs_header_nritems(leaf) == 0) {
4732 path->slots[1] = slot;
4733 btrfs_del_leaf(trans, root, path, leaf);
4734 free_extent_buffer(leaf);
4735 ret = 0;
4736 } else {
4737 /* if we're still in the path, make sure
4738 * we're dirty. Otherwise, one of the
4739 * push_leaf functions must have already
4740 * dirtied this buffer
4741 */
4742 if (path->nodes[0] == leaf)
4743 btrfs_mark_buffer_dirty(leaf);
4744 free_extent_buffer(leaf);
4745 }
4746 } else {
4747 btrfs_mark_buffer_dirty(leaf);
4748 }
4749 }
4750 return ret;
4751}
4752
4753/*
4754 * search the tree again to find a leaf with lesser keys
4755 * returns 0 if it found something or 1 if there are no lesser leaves.
4756 * returns < 0 on io errors.
4757 *
4758 * This may release the path, and so you may lose any locks held at the
4759 * time you call it.
4760 */
4761int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
4762{
4763 struct btrfs_key key;
4764 struct btrfs_disk_key found_key;
4765 int ret;
4766
4767 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
4768
4769 if (key.offset > 0)
4770 key.offset--;
4771 else if (key.type > 0)
4772 key.type--;
4773 else if (key.objectid > 0)
4774 key.objectid--;
4775 else
4776 return 1;
4777
4778 btrfs_release_path(path);
4779 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4780 if (ret < 0)
4781 return ret;
4782 btrfs_item_key(path->nodes[0], &found_key, 0);
4783 ret = comp_keys(&found_key, &key);
4784 if (ret < 0)
4785 return 0;
4786 return 1;
4787}
4788
4789/*
4790 * A helper function to walk down the tree starting at min_key, and looking
4791 * for nodes or leaves that are either in cache or have a minimum
4792 * transaction id. This is used by the btree defrag code, and tree logging
4793 *
4794 * This does not cow, but it does stuff the starting key it finds back
4795 * into min_key, so you can call btrfs_search_slot with cow=1 on the
4796 * key and get a writable path.
4797 *
4798 * This does lock as it descends, and path->keep_locks should be set
4799 * to 1 by the caller.
4800 *
4801 * This honors path->lowest_level to prevent descent past a given level
4802 * of the tree.
4803 *
4804 * min_trans indicates the oldest transaction that you are interested
4805 * in walking through. Any nodes or leaves older than min_trans are
4806 * skipped over (without reading them).
4807 *
4808 * returns zero if something useful was found, < 0 on error and 1 if there
4809 * was nothing in the tree that matched the search criteria.
4810 */
4811int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4812 struct btrfs_key *max_key,
4813 struct btrfs_path *path, int cache_only,
4814 u64 min_trans)
4815{
4816 struct extent_buffer *cur;
4817 struct btrfs_key found_key;
4818 int slot;
4819 int sret;
4820 u32 nritems;
4821 int level;
4822 int ret = 1;
4823
4824 WARN_ON(!path->keep_locks);
4825again:
4826 cur = btrfs_read_lock_root_node(root);
4827 level = btrfs_header_level(cur);
4828 WARN_ON(path->nodes[level]);
4829 path->nodes[level] = cur;
4830 path->locks[level] = BTRFS_READ_LOCK;
4831
4832 if (btrfs_header_generation(cur) < min_trans) {
4833 ret = 1;
4834 goto out;
4835 }
4836 while (1) {
4837 nritems = btrfs_header_nritems(cur);
4838 level = btrfs_header_level(cur);
4839 sret = bin_search(cur, min_key, level, &slot);
4840
4841 /* at the lowest level, we're done, setup the path and exit */
4842 if (level == path->lowest_level) {
4843 if (slot >= nritems)
4844 goto find_next_key;
4845 ret = 0;
4846 path->slots[level] = slot;
4847 btrfs_item_key_to_cpu(cur, &found_key, slot);
4848 goto out;
4849 }
4850 if (sret && slot > 0)
4851 slot--;
4852 /*
4853 * check this node pointer against the cache_only and
4854 * min_trans parameters. If it isn't in cache or is too
4855 * old, skip to the next one.
4856 */
4857 while (slot < nritems) {
4858 u64 blockptr;
4859 u64 gen;
4860 struct extent_buffer *tmp;
4861 struct btrfs_disk_key disk_key;
4862
4863 blockptr = btrfs_node_blockptr(cur, slot);
4864 gen = btrfs_node_ptr_generation(cur, slot);
4865 if (gen < min_trans) {
4866 slot++;
4867 continue;
4868 }
4869 if (!cache_only)
4870 break;
4871
4872 if (max_key) {
4873 btrfs_node_key(cur, &disk_key, slot);
4874 if (comp_keys(&disk_key, max_key) >= 0) {
4875 ret = 1;
4876 goto out;
4877 }
4878 }
4879
4880 tmp = btrfs_find_tree_block(root, blockptr,
4881 btrfs_level_size(root, level - 1));
4882
4883 if (tmp && btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
4884 free_extent_buffer(tmp);
4885 break;
4886 }
4887 if (tmp)
4888 free_extent_buffer(tmp);
4889 slot++;
4890 }
4891find_next_key:
4892 /*
4893 * we didn't find a candidate key in this node, walk forward
4894 * and find another one
4895 */
4896 if (slot >= nritems) {
4897 path->slots[level] = slot;
4898 btrfs_set_path_blocking(path);
4899 sret = btrfs_find_next_key(root, path, min_key, level,
4900 cache_only, min_trans);
4901 if (sret == 0) {
4902 btrfs_release_path(path);
4903 goto again;
4904 } else {
4905 goto out;
4906 }
4907 }
4908 /* save our key for returning back */
4909 btrfs_node_key_to_cpu(cur, &found_key, slot);
4910 path->slots[level] = slot;
4911 if (level == path->lowest_level) {
4912 ret = 0;
4913 unlock_up(path, level, 1, 0, NULL);
4914 goto out;
4915 }
4916 btrfs_set_path_blocking(path);
4917 cur = read_node_slot(root, cur, slot);
4918 BUG_ON(!cur); /* -ENOMEM */
4919
4920 btrfs_tree_read_lock(cur);
4921
4922 path->locks[level - 1] = BTRFS_READ_LOCK;
4923 path->nodes[level - 1] = cur;
4924 unlock_up(path, level, 1, 0, NULL);
4925 btrfs_clear_path_blocking(path, NULL, 0);
4926 }
4927out:
4928 if (ret == 0)
4929 memcpy(min_key, &found_key, sizeof(found_key));
4930 btrfs_set_path_blocking(path);
4931 return ret;
4932}
4933
4934/*
4935 * this is similar to btrfs_next_leaf, but does not try to preserve
4936 * and fixup the path. It looks for and returns the next key in the
4937 * tree based on the current path and the cache_only and min_trans
4938 * parameters.
4939 *
4940 * 0 is returned if another key is found, < 0 if there are any errors
4941 * and 1 is returned if there are no higher keys in the tree
4942 *
4943 * path->keep_locks should be set to 1 on the search made before
4944 * calling this function.
4945 */
4946int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4947 struct btrfs_key *key, int level,
4948 int cache_only, u64 min_trans)
4949{
4950 int slot;
4951 struct extent_buffer *c;
4952
4953 WARN_ON(!path->keep_locks);
4954 while (level < BTRFS_MAX_LEVEL) {
4955 if (!path->nodes[level])
4956 return 1;
4957
4958 slot = path->slots[level] + 1;
4959 c = path->nodes[level];
4960next:
4961 if (slot >= btrfs_header_nritems(c)) {
4962 int ret;
4963 int orig_lowest;
4964 struct btrfs_key cur_key;
4965 if (level + 1 >= BTRFS_MAX_LEVEL ||
4966 !path->nodes[level + 1])
4967 return 1;
4968
4969 if (path->locks[level + 1]) {
4970 level++;
4971 continue;
4972 }
4973
4974 slot = btrfs_header_nritems(c) - 1;
4975 if (level == 0)
4976 btrfs_item_key_to_cpu(c, &cur_key, slot);
4977 else
4978 btrfs_node_key_to_cpu(c, &cur_key, slot);
4979
4980 orig_lowest = path->lowest_level;
4981 btrfs_release_path(path);
4982 path->lowest_level = level;
4983 ret = btrfs_search_slot(NULL, root, &cur_key, path,
4984 0, 0);
4985 path->lowest_level = orig_lowest;
4986 if (ret < 0)
4987 return ret;
4988
4989 c = path->nodes[level];
4990 slot = path->slots[level];
4991 if (ret == 0)
4992 slot++;
4993 goto next;
4994 }
4995
4996 if (level == 0)
4997 btrfs_item_key_to_cpu(c, key, slot);
4998 else {
4999 u64 blockptr = btrfs_node_blockptr(c, slot);
5000 u64 gen = btrfs_node_ptr_generation(c, slot);
5001
5002 if (cache_only) {
5003 struct extent_buffer *cur;
5004 cur = btrfs_find_tree_block(root, blockptr,
5005 btrfs_level_size(root, level - 1));
5006 if (!cur ||
5007 btrfs_buffer_uptodate(cur, gen, 1) <= 0) {
5008 slot++;
5009 if (cur)
5010 free_extent_buffer(cur);
5011 goto next;
5012 }
5013 free_extent_buffer(cur);
5014 }
5015 if (gen < min_trans) {
5016 slot++;
5017 goto next;
5018 }
5019 btrfs_node_key_to_cpu(c, key, slot);
5020 }
5021 return 0;
5022 }
5023 return 1;
5024}
5025
5026/*
5027 * search the tree again to find a leaf with greater keys
5028 * returns 0 if it found something or 1 if there are no greater leaves.
5029 * returns < 0 on io errors.
5030 */
5031int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
5032{
5033 return btrfs_next_old_leaf(root, path, 0);
5034}
5035
5036int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
5037 u64 time_seq)
5038{
5039 int slot;
5040 int level;
5041 struct extent_buffer *c;
5042 struct extent_buffer *next;
5043 struct btrfs_key key;
5044 u32 nritems;
5045 int ret;
5046 int old_spinning = path->leave_spinning;
5047 int next_rw_lock = 0;
5048
5049 nritems = btrfs_header_nritems(path->nodes[0]);
5050 if (nritems == 0)
5051 return 1;
5052
5053 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5054again:
5055 level = 1;
5056 next = NULL;
5057 next_rw_lock = 0;
5058 btrfs_release_path(path);
5059
5060 path->keep_locks = 1;
5061 path->leave_spinning = 1;
5062
5063 if (time_seq)
5064 ret = btrfs_search_old_slot(root, &key, path, time_seq);
5065 else
5066 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5067 path->keep_locks = 0;
5068
5069 if (ret < 0)
5070 return ret;
5071
5072 nritems = btrfs_header_nritems(path->nodes[0]);
5073 /*
5074 * by releasing the path above we dropped all our locks. A balance
5075 * could have added more items next to the key that used to be
5076 * at the very end of the block. So, check again here and
5077 * advance the path if there are now more items available.
5078 */
5079 if (nritems > 0 && path->slots[0] < nritems - 1) {
5080 if (ret == 0)
5081 path->slots[0]++;
5082 ret = 0;
5083 goto done;
5084 }
5085
5086 while (level < BTRFS_MAX_LEVEL) {
5087 if (!path->nodes[level]) {
5088 ret = 1;
5089 goto done;
5090 }
5091
5092 slot = path->slots[level] + 1;
5093 c = path->nodes[level];
5094 if (slot >= btrfs_header_nritems(c)) {
5095 level++;
5096 if (level == BTRFS_MAX_LEVEL) {
5097 ret = 1;
5098 goto done;
5099 }
5100 continue;
5101 }
5102
5103 if (next) {
5104 btrfs_tree_unlock_rw(next, next_rw_lock);
5105 free_extent_buffer(next);
5106 }
5107
5108 next = c;
5109 next_rw_lock = path->locks[level];
5110 ret = read_block_for_search(NULL, root, path, &next, level,
5111 slot, &key, 0);
5112 if (ret == -EAGAIN)
5113 goto again;
5114
5115 if (ret < 0) {
5116 btrfs_release_path(path);
5117 goto done;
5118 }
5119
5120 if (!path->skip_locking) {
5121 ret = btrfs_try_tree_read_lock(next);
5122 if (!ret && time_seq) {
5123 /*
5124 * If we don't get the lock, we may be racing
5125 * with push_leaf_left, holding that lock while
5126 * itself waiting for the leaf we've currently
5127 * locked. To solve this situation, we give up
5128 * on our lock and cycle.
5129 */
5130 btrfs_release_path(path);
5131 cond_resched();
5132 goto again;
5133 }
5134 if (!ret) {
5135 btrfs_set_path_blocking(path);
5136 btrfs_tree_read_lock(next);
5137 btrfs_clear_path_blocking(path, next,
5138 BTRFS_READ_LOCK);
5139 }
5140 next_rw_lock = BTRFS_READ_LOCK;
5141 }
5142 break;
5143 }
5144 path->slots[level] = slot;
5145 while (1) {
5146 level--;
5147 c = path->nodes[level];
5148 if (path->locks[level])
5149 btrfs_tree_unlock_rw(c, path->locks[level]);
5150
5151 free_extent_buffer(c);
5152 path->nodes[level] = next;
5153 path->slots[level] = 0;
5154 if (!path->skip_locking)
5155 path->locks[level] = next_rw_lock;
5156 if (!level)
5157 break;
5158
5159 ret = read_block_for_search(NULL, root, path, &next, level,
5160 0, &key, 0);
5161 if (ret == -EAGAIN)
5162 goto again;
5163
5164 if (ret < 0) {
5165 btrfs_release_path(path);
5166 goto done;
5167 }
5168
5169 if (!path->skip_locking) {
5170 ret = btrfs_try_tree_read_lock(next);
5171 if (!ret) {
5172 btrfs_set_path_blocking(path);
5173 btrfs_tree_read_lock(next);
5174 btrfs_clear_path_blocking(path, next,
5175 BTRFS_READ_LOCK);
5176 }
5177 next_rw_lock = BTRFS_READ_LOCK;
5178 }
5179 }
5180 ret = 0;
5181done:
5182 unlock_up(path, 0, 1, 0, NULL);
5183 path->leave_spinning = old_spinning;
5184 if (!old_spinning)
5185 btrfs_set_path_blocking(path);
5186
5187 return ret;
5188}
5189
5190/*
5191 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5192 * searching until it gets past min_objectid or finds an item of 'type'
5193 *
5194 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5195 */
5196int btrfs_previous_item(struct btrfs_root *root,
5197 struct btrfs_path *path, u64 min_objectid,
5198 int type)
5199{
5200 struct btrfs_key found_key;
5201 struct extent_buffer *leaf;
5202 u32 nritems;
5203 int ret;
5204
5205 while (1) {
5206 if (path->slots[0] == 0) {
5207 btrfs_set_path_blocking(path);
5208 ret = btrfs_prev_leaf(root, path);
5209 if (ret != 0)
5210 return ret;
5211 } else {
5212 path->slots[0]--;
5213 }
5214 leaf = path->nodes[0];
5215 nritems = btrfs_header_nritems(leaf);
5216 if (nritems == 0)
5217 return 1;
5218 if (path->slots[0] == nritems)
5219 path->slots[0]--;
5220
5221 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5222 if (found_key.objectid < min_objectid)
5223 break;
5224 if (found_key.type == type)
5225 return 0;
5226 if (found_key.objectid == min_objectid &&
5227 found_key.type < type)
5228 break;
5229 }
5230 return 1;
5231}