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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 "ctree.h"
22#include "disk-io.h"
23#include "transaction.h"
24#include "print-tree.h"
25#include "locking.h"
26
27static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
28 *root, struct btrfs_path *path, int level);
29static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
30 *root, struct btrfs_key *ins_key,
31 struct btrfs_path *path, int data_size, int extend);
32static int push_node_left(struct btrfs_trans_handle *trans,
33 struct btrfs_root *root, struct extent_buffer *dst,
34 struct extent_buffer *src, int empty);
35static int balance_node_right(struct btrfs_trans_handle *trans,
36 struct btrfs_root *root,
37 struct extent_buffer *dst_buf,
38 struct extent_buffer *src_buf);
39static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
40 struct btrfs_path *path, int level, int slot);
41
42struct btrfs_path *btrfs_alloc_path(void)
43{
44 struct btrfs_path *path;
45 path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
46 return path;
47}
48
49/*
50 * set all locked nodes in the path to blocking locks. This should
51 * be done before scheduling
52 */
53noinline void btrfs_set_path_blocking(struct btrfs_path *p)
54{
55 int i;
56 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
57 if (!p->nodes[i] || !p->locks[i])
58 continue;
59 btrfs_set_lock_blocking_rw(p->nodes[i], p->locks[i]);
60 if (p->locks[i] == BTRFS_READ_LOCK)
61 p->locks[i] = BTRFS_READ_LOCK_BLOCKING;
62 else if (p->locks[i] == BTRFS_WRITE_LOCK)
63 p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING;
64 }
65}
66
67/*
68 * reset all the locked nodes in the patch to spinning locks.
69 *
70 * held is used to keep lockdep happy, when lockdep is enabled
71 * we set held to a blocking lock before we go around and
72 * retake all the spinlocks in the path. You can safely use NULL
73 * for held
74 */
75noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
76 struct extent_buffer *held, int held_rw)
77{
78 int i;
79
80#ifdef CONFIG_DEBUG_LOCK_ALLOC
81 /* lockdep really cares that we take all of these spinlocks
82 * in the right order. If any of the locks in the path are not
83 * currently blocking, it is going to complain. So, make really
84 * really sure by forcing the path to blocking before we clear
85 * the path blocking.
86 */
87 if (held) {
88 btrfs_set_lock_blocking_rw(held, held_rw);
89 if (held_rw == BTRFS_WRITE_LOCK)
90 held_rw = BTRFS_WRITE_LOCK_BLOCKING;
91 else if (held_rw == BTRFS_READ_LOCK)
92 held_rw = BTRFS_READ_LOCK_BLOCKING;
93 }
94 btrfs_set_path_blocking(p);
95#endif
96
97 for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
98 if (p->nodes[i] && p->locks[i]) {
99 btrfs_clear_lock_blocking_rw(p->nodes[i], p->locks[i]);
100 if (p->locks[i] == BTRFS_WRITE_LOCK_BLOCKING)
101 p->locks[i] = BTRFS_WRITE_LOCK;
102 else if (p->locks[i] == BTRFS_READ_LOCK_BLOCKING)
103 p->locks[i] = BTRFS_READ_LOCK;
104 }
105 }
106
107#ifdef CONFIG_DEBUG_LOCK_ALLOC
108 if (held)
109 btrfs_clear_lock_blocking_rw(held, held_rw);
110#endif
111}
112
113/* this also releases the path */
114void btrfs_free_path(struct btrfs_path *p)
115{
116 if (!p)
117 return;
118 btrfs_release_path(p);
119 kmem_cache_free(btrfs_path_cachep, p);
120}
121
122/*
123 * path release drops references on the extent buffers in the path
124 * and it drops any locks held by this path
125 *
126 * It is safe to call this on paths that no locks or extent buffers held.
127 */
128noinline void btrfs_release_path(struct btrfs_path *p)
129{
130 int i;
131
132 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
133 p->slots[i] = 0;
134 if (!p->nodes[i])
135 continue;
136 if (p->locks[i]) {
137 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
138 p->locks[i] = 0;
139 }
140 free_extent_buffer(p->nodes[i]);
141 p->nodes[i] = NULL;
142 }
143}
144
145/*
146 * safely gets a reference on the root node of a tree. A lock
147 * is not taken, so a concurrent writer may put a different node
148 * at the root of the tree. See btrfs_lock_root_node for the
149 * looping required.
150 *
151 * The extent buffer returned by this has a reference taken, so
152 * it won't disappear. It may stop being the root of the tree
153 * at any time because there are no locks held.
154 */
155struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
156{
157 struct extent_buffer *eb;
158
159 rcu_read_lock();
160 eb = rcu_dereference(root->node);
161 extent_buffer_get(eb);
162 rcu_read_unlock();
163 return eb;
164}
165
166/* loop around taking references on and locking the root node of the
167 * tree until you end up with a lock on the root. A locked buffer
168 * is returned, with a reference held.
169 */
170struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
171{
172 struct extent_buffer *eb;
173
174 while (1) {
175 eb = btrfs_root_node(root);
176 btrfs_tree_lock(eb);
177 if (eb == root->node)
178 break;
179 btrfs_tree_unlock(eb);
180 free_extent_buffer(eb);
181 }
182 return eb;
183}
184
185/* loop around taking references on and locking the root node of the
186 * tree until you end up with a lock on the root. A locked buffer
187 * is returned, with a reference held.
188 */
189struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
190{
191 struct extent_buffer *eb;
192
193 while (1) {
194 eb = btrfs_root_node(root);
195 btrfs_tree_read_lock(eb);
196 if (eb == root->node)
197 break;
198 btrfs_tree_read_unlock(eb);
199 free_extent_buffer(eb);
200 }
201 return eb;
202}
203
204/* cowonly root (everything not a reference counted cow subvolume), just get
205 * put onto a simple dirty list. transaction.c walks this to make sure they
206 * get properly updated on disk.
207 */
208static void add_root_to_dirty_list(struct btrfs_root *root)
209{
210 if (root->track_dirty && list_empty(&root->dirty_list)) {
211 list_add(&root->dirty_list,
212 &root->fs_info->dirty_cowonly_roots);
213 }
214}
215
216/*
217 * used by snapshot creation to make a copy of a root for a tree with
218 * a given objectid. The buffer with the new root node is returned in
219 * cow_ret, and this func returns zero on success or a negative error code.
220 */
221int btrfs_copy_root(struct btrfs_trans_handle *trans,
222 struct btrfs_root *root,
223 struct extent_buffer *buf,
224 struct extent_buffer **cow_ret, u64 new_root_objectid)
225{
226 struct extent_buffer *cow;
227 int ret = 0;
228 int level;
229 struct btrfs_disk_key disk_key;
230
231 WARN_ON(root->ref_cows && trans->transid !=
232 root->fs_info->running_transaction->transid);
233 WARN_ON(root->ref_cows && trans->transid != root->last_trans);
234
235 level = btrfs_header_level(buf);
236 if (level == 0)
237 btrfs_item_key(buf, &disk_key, 0);
238 else
239 btrfs_node_key(buf, &disk_key, 0);
240
241 cow = btrfs_alloc_free_block(trans, root, buf->len, 0,
242 new_root_objectid, &disk_key, level,
243 buf->start, 0);
244 if (IS_ERR(cow))
245 return PTR_ERR(cow);
246
247 copy_extent_buffer(cow, buf, 0, 0, cow->len);
248 btrfs_set_header_bytenr(cow, cow->start);
249 btrfs_set_header_generation(cow, trans->transid);
250 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
251 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
252 BTRFS_HEADER_FLAG_RELOC);
253 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
254 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
255 else
256 btrfs_set_header_owner(cow, new_root_objectid);
257
258 write_extent_buffer(cow, root->fs_info->fsid,
259 (unsigned long)btrfs_header_fsid(cow),
260 BTRFS_FSID_SIZE);
261
262 WARN_ON(btrfs_header_generation(buf) > trans->transid);
263 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
264 ret = btrfs_inc_ref(trans, root, cow, 1);
265 else
266 ret = btrfs_inc_ref(trans, root, cow, 0);
267
268 if (ret)
269 return ret;
270
271 btrfs_mark_buffer_dirty(cow);
272 *cow_ret = cow;
273 return 0;
274}
275
276/*
277 * check if the tree block can be shared by multiple trees
278 */
279int btrfs_block_can_be_shared(struct btrfs_root *root,
280 struct extent_buffer *buf)
281{
282 /*
283 * Tree blocks not in refernece counted trees and tree roots
284 * are never shared. If a block was allocated after the last
285 * snapshot and the block was not allocated by tree relocation,
286 * we know the block is not shared.
287 */
288 if (root->ref_cows &&
289 buf != root->node && buf != root->commit_root &&
290 (btrfs_header_generation(buf) <=
291 btrfs_root_last_snapshot(&root->root_item) ||
292 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
293 return 1;
294#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
295 if (root->ref_cows &&
296 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
297 return 1;
298#endif
299 return 0;
300}
301
302static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
303 struct btrfs_root *root,
304 struct extent_buffer *buf,
305 struct extent_buffer *cow,
306 int *last_ref)
307{
308 u64 refs;
309 u64 owner;
310 u64 flags;
311 u64 new_flags = 0;
312 int ret;
313
314 /*
315 * Backrefs update rules:
316 *
317 * Always use full backrefs for extent pointers in tree block
318 * allocated by tree relocation.
319 *
320 * If a shared tree block is no longer referenced by its owner
321 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
322 * use full backrefs for extent pointers in tree block.
323 *
324 * If a tree block is been relocating
325 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
326 * use full backrefs for extent pointers in tree block.
327 * The reason for this is some operations (such as drop tree)
328 * are only allowed for blocks use full backrefs.
329 */
330
331 if (btrfs_block_can_be_shared(root, buf)) {
332 ret = btrfs_lookup_extent_info(trans, root, buf->start,
333 buf->len, &refs, &flags);
334 BUG_ON(ret);
335 BUG_ON(refs == 0);
336 } else {
337 refs = 1;
338 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
339 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
340 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
341 else
342 flags = 0;
343 }
344
345 owner = btrfs_header_owner(buf);
346 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
347 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
348
349 if (refs > 1) {
350 if ((owner == root->root_key.objectid ||
351 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
352 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
353 ret = btrfs_inc_ref(trans, root, buf, 1);
354 BUG_ON(ret);
355
356 if (root->root_key.objectid ==
357 BTRFS_TREE_RELOC_OBJECTID) {
358 ret = btrfs_dec_ref(trans, root, buf, 0);
359 BUG_ON(ret);
360 ret = btrfs_inc_ref(trans, root, cow, 1);
361 BUG_ON(ret);
362 }
363 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
364 } else {
365
366 if (root->root_key.objectid ==
367 BTRFS_TREE_RELOC_OBJECTID)
368 ret = btrfs_inc_ref(trans, root, cow, 1);
369 else
370 ret = btrfs_inc_ref(trans, root, cow, 0);
371 BUG_ON(ret);
372 }
373 if (new_flags != 0) {
374 ret = btrfs_set_disk_extent_flags(trans, root,
375 buf->start,
376 buf->len,
377 new_flags, 0);
378 BUG_ON(ret);
379 }
380 } else {
381 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
382 if (root->root_key.objectid ==
383 BTRFS_TREE_RELOC_OBJECTID)
384 ret = btrfs_inc_ref(trans, root, cow, 1);
385 else
386 ret = btrfs_inc_ref(trans, root, cow, 0);
387 BUG_ON(ret);
388 ret = btrfs_dec_ref(trans, root, buf, 1);
389 BUG_ON(ret);
390 }
391 clean_tree_block(trans, root, buf);
392 *last_ref = 1;
393 }
394 return 0;
395}
396
397/*
398 * does the dirty work in cow of a single block. The parent block (if
399 * supplied) is updated to point to the new cow copy. The new buffer is marked
400 * dirty and returned locked. If you modify the block it needs to be marked
401 * dirty again.
402 *
403 * search_start -- an allocation hint for the new block
404 *
405 * empty_size -- a hint that you plan on doing more cow. This is the size in
406 * bytes the allocator should try to find free next to the block it returns.
407 * This is just a hint and may be ignored by the allocator.
408 */
409static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
410 struct btrfs_root *root,
411 struct extent_buffer *buf,
412 struct extent_buffer *parent, int parent_slot,
413 struct extent_buffer **cow_ret,
414 u64 search_start, u64 empty_size)
415{
416 struct btrfs_disk_key disk_key;
417 struct extent_buffer *cow;
418 int level;
419 int last_ref = 0;
420 int unlock_orig = 0;
421 u64 parent_start;
422
423 if (*cow_ret == buf)
424 unlock_orig = 1;
425
426 btrfs_assert_tree_locked(buf);
427
428 WARN_ON(root->ref_cows && trans->transid !=
429 root->fs_info->running_transaction->transid);
430 WARN_ON(root->ref_cows && trans->transid != root->last_trans);
431
432 level = btrfs_header_level(buf);
433
434 if (level == 0)
435 btrfs_item_key(buf, &disk_key, 0);
436 else
437 btrfs_node_key(buf, &disk_key, 0);
438
439 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
440 if (parent)
441 parent_start = parent->start;
442 else
443 parent_start = 0;
444 } else
445 parent_start = 0;
446
447 cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start,
448 root->root_key.objectid, &disk_key,
449 level, search_start, empty_size);
450 if (IS_ERR(cow))
451 return PTR_ERR(cow);
452
453 /* cow is set to blocking by btrfs_init_new_buffer */
454
455 copy_extent_buffer(cow, buf, 0, 0, cow->len);
456 btrfs_set_header_bytenr(cow, cow->start);
457 btrfs_set_header_generation(cow, trans->transid);
458 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
459 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
460 BTRFS_HEADER_FLAG_RELOC);
461 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
462 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
463 else
464 btrfs_set_header_owner(cow, root->root_key.objectid);
465
466 write_extent_buffer(cow, root->fs_info->fsid,
467 (unsigned long)btrfs_header_fsid(cow),
468 BTRFS_FSID_SIZE);
469
470 update_ref_for_cow(trans, root, buf, cow, &last_ref);
471
472 if (root->ref_cows)
473 btrfs_reloc_cow_block(trans, root, buf, cow);
474
475 if (buf == root->node) {
476 WARN_ON(parent && parent != buf);
477 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
478 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
479 parent_start = buf->start;
480 else
481 parent_start = 0;
482
483 extent_buffer_get(cow);
484 rcu_assign_pointer(root->node, cow);
485
486 btrfs_free_tree_block(trans, root, buf, parent_start,
487 last_ref);
488 free_extent_buffer(buf);
489 add_root_to_dirty_list(root);
490 } else {
491 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
492 parent_start = parent->start;
493 else
494 parent_start = 0;
495
496 WARN_ON(trans->transid != btrfs_header_generation(parent));
497 btrfs_set_node_blockptr(parent, parent_slot,
498 cow->start);
499 btrfs_set_node_ptr_generation(parent, parent_slot,
500 trans->transid);
501 btrfs_mark_buffer_dirty(parent);
502 btrfs_free_tree_block(trans, root, buf, parent_start,
503 last_ref);
504 }
505 if (unlock_orig)
506 btrfs_tree_unlock(buf);
507 free_extent_buffer(buf);
508 btrfs_mark_buffer_dirty(cow);
509 *cow_ret = cow;
510 return 0;
511}
512
513static inline int should_cow_block(struct btrfs_trans_handle *trans,
514 struct btrfs_root *root,
515 struct extent_buffer *buf)
516{
517 if (btrfs_header_generation(buf) == trans->transid &&
518 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
519 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
520 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
521 return 0;
522 return 1;
523}
524
525/*
526 * cows a single block, see __btrfs_cow_block for the real work.
527 * This version of it has extra checks so that a block isn't cow'd more than
528 * once per transaction, as long as it hasn't been written yet
529 */
530noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
531 struct btrfs_root *root, struct extent_buffer *buf,
532 struct extent_buffer *parent, int parent_slot,
533 struct extent_buffer **cow_ret)
534{
535 u64 search_start;
536 int ret;
537
538 if (trans->transaction != root->fs_info->running_transaction) {
539 printk(KERN_CRIT "trans %llu running %llu\n",
540 (unsigned long long)trans->transid,
541 (unsigned long long)
542 root->fs_info->running_transaction->transid);
543 WARN_ON(1);
544 }
545 if (trans->transid != root->fs_info->generation) {
546 printk(KERN_CRIT "trans %llu running %llu\n",
547 (unsigned long long)trans->transid,
548 (unsigned long long)root->fs_info->generation);
549 WARN_ON(1);
550 }
551
552 if (!should_cow_block(trans, root, buf)) {
553 *cow_ret = buf;
554 return 0;
555 }
556
557 search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
558
559 if (parent)
560 btrfs_set_lock_blocking(parent);
561 btrfs_set_lock_blocking(buf);
562
563 ret = __btrfs_cow_block(trans, root, buf, parent,
564 parent_slot, cow_ret, search_start, 0);
565
566 trace_btrfs_cow_block(root, buf, *cow_ret);
567
568 return ret;
569}
570
571/*
572 * helper function for defrag to decide if two blocks pointed to by a
573 * node are actually close by
574 */
575static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
576{
577 if (blocknr < other && other - (blocknr + blocksize) < 32768)
578 return 1;
579 if (blocknr > other && blocknr - (other + blocksize) < 32768)
580 return 1;
581 return 0;
582}
583
584/*
585 * compare two keys in a memcmp fashion
586 */
587static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
588{
589 struct btrfs_key k1;
590
591 btrfs_disk_key_to_cpu(&k1, disk);
592
593 return btrfs_comp_cpu_keys(&k1, k2);
594}
595
596/*
597 * same as comp_keys only with two btrfs_key's
598 */
599int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2)
600{
601 if (k1->objectid > k2->objectid)
602 return 1;
603 if (k1->objectid < k2->objectid)
604 return -1;
605 if (k1->type > k2->type)
606 return 1;
607 if (k1->type < k2->type)
608 return -1;
609 if (k1->offset > k2->offset)
610 return 1;
611 if (k1->offset < k2->offset)
612 return -1;
613 return 0;
614}
615
616/*
617 * this is used by the defrag code to go through all the
618 * leaves pointed to by a node and reallocate them so that
619 * disk order is close to key order
620 */
621int btrfs_realloc_node(struct btrfs_trans_handle *trans,
622 struct btrfs_root *root, struct extent_buffer *parent,
623 int start_slot, int cache_only, u64 *last_ret,
624 struct btrfs_key *progress)
625{
626 struct extent_buffer *cur;
627 u64 blocknr;
628 u64 gen;
629 u64 search_start = *last_ret;
630 u64 last_block = 0;
631 u64 other;
632 u32 parent_nritems;
633 int end_slot;
634 int i;
635 int err = 0;
636 int parent_level;
637 int uptodate;
638 u32 blocksize;
639 int progress_passed = 0;
640 struct btrfs_disk_key disk_key;
641
642 parent_level = btrfs_header_level(parent);
643 if (cache_only && parent_level != 1)
644 return 0;
645
646 if (trans->transaction != root->fs_info->running_transaction)
647 WARN_ON(1);
648 if (trans->transid != root->fs_info->generation)
649 WARN_ON(1);
650
651 parent_nritems = btrfs_header_nritems(parent);
652 blocksize = btrfs_level_size(root, parent_level - 1);
653 end_slot = parent_nritems;
654
655 if (parent_nritems == 1)
656 return 0;
657
658 btrfs_set_lock_blocking(parent);
659
660 for (i = start_slot; i < end_slot; i++) {
661 int close = 1;
662
663 btrfs_node_key(parent, &disk_key, i);
664 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
665 continue;
666
667 progress_passed = 1;
668 blocknr = btrfs_node_blockptr(parent, i);
669 gen = btrfs_node_ptr_generation(parent, i);
670 if (last_block == 0)
671 last_block = blocknr;
672
673 if (i > 0) {
674 other = btrfs_node_blockptr(parent, i - 1);
675 close = close_blocks(blocknr, other, blocksize);
676 }
677 if (!close && i < end_slot - 2) {
678 other = btrfs_node_blockptr(parent, i + 1);
679 close = close_blocks(blocknr, other, blocksize);
680 }
681 if (close) {
682 last_block = blocknr;
683 continue;
684 }
685
686 cur = btrfs_find_tree_block(root, blocknr, blocksize);
687 if (cur)
688 uptodate = btrfs_buffer_uptodate(cur, gen);
689 else
690 uptodate = 0;
691 if (!cur || !uptodate) {
692 if (cache_only) {
693 free_extent_buffer(cur);
694 continue;
695 }
696 if (!cur) {
697 cur = read_tree_block(root, blocknr,
698 blocksize, gen);
699 if (!cur)
700 return -EIO;
701 } else if (!uptodate) {
702 btrfs_read_buffer(cur, gen);
703 }
704 }
705 if (search_start == 0)
706 search_start = last_block;
707
708 btrfs_tree_lock(cur);
709 btrfs_set_lock_blocking(cur);
710 err = __btrfs_cow_block(trans, root, cur, parent, i,
711 &cur, search_start,
712 min(16 * blocksize,
713 (end_slot - i) * blocksize));
714 if (err) {
715 btrfs_tree_unlock(cur);
716 free_extent_buffer(cur);
717 break;
718 }
719 search_start = cur->start;
720 last_block = cur->start;
721 *last_ret = search_start;
722 btrfs_tree_unlock(cur);
723 free_extent_buffer(cur);
724 }
725 return err;
726}
727
728/*
729 * The leaf data grows from end-to-front in the node.
730 * this returns the address of the start of the last item,
731 * which is the stop of the leaf data stack
732 */
733static inline unsigned int leaf_data_end(struct btrfs_root *root,
734 struct extent_buffer *leaf)
735{
736 u32 nr = btrfs_header_nritems(leaf);
737 if (nr == 0)
738 return BTRFS_LEAF_DATA_SIZE(root);
739 return btrfs_item_offset_nr(leaf, nr - 1);
740}
741
742
743/*
744 * search for key in the extent_buffer. The items start at offset p,
745 * and they are item_size apart. There are 'max' items in p.
746 *
747 * the slot in the array is returned via slot, and it points to
748 * the place where you would insert key if it is not found in
749 * the array.
750 *
751 * slot may point to max if the key is bigger than all of the keys
752 */
753static noinline int generic_bin_search(struct extent_buffer *eb,
754 unsigned long p,
755 int item_size, struct btrfs_key *key,
756 int max, int *slot)
757{
758 int low = 0;
759 int high = max;
760 int mid;
761 int ret;
762 struct btrfs_disk_key *tmp = NULL;
763 struct btrfs_disk_key unaligned;
764 unsigned long offset;
765 char *kaddr = NULL;
766 unsigned long map_start = 0;
767 unsigned long map_len = 0;
768 int err;
769
770 while (low < high) {
771 mid = (low + high) / 2;
772 offset = p + mid * item_size;
773
774 if (!kaddr || offset < map_start ||
775 (offset + sizeof(struct btrfs_disk_key)) >
776 map_start + map_len) {
777
778 err = map_private_extent_buffer(eb, offset,
779 sizeof(struct btrfs_disk_key),
780 &kaddr, &map_start, &map_len);
781
782 if (!err) {
783 tmp = (struct btrfs_disk_key *)(kaddr + offset -
784 map_start);
785 } else {
786 read_extent_buffer(eb, &unaligned,
787 offset, sizeof(unaligned));
788 tmp = &unaligned;
789 }
790
791 } else {
792 tmp = (struct btrfs_disk_key *)(kaddr + offset -
793 map_start);
794 }
795 ret = comp_keys(tmp, key);
796
797 if (ret < 0)
798 low = mid + 1;
799 else if (ret > 0)
800 high = mid;
801 else {
802 *slot = mid;
803 return 0;
804 }
805 }
806 *slot = low;
807 return 1;
808}
809
810/*
811 * simple bin_search frontend that does the right thing for
812 * leaves vs nodes
813 */
814static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
815 int level, int *slot)
816{
817 if (level == 0) {
818 return generic_bin_search(eb,
819 offsetof(struct btrfs_leaf, items),
820 sizeof(struct btrfs_item),
821 key, btrfs_header_nritems(eb),
822 slot);
823 } else {
824 return generic_bin_search(eb,
825 offsetof(struct btrfs_node, ptrs),
826 sizeof(struct btrfs_key_ptr),
827 key, btrfs_header_nritems(eb),
828 slot);
829 }
830 return -1;
831}
832
833int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
834 int level, int *slot)
835{
836 return bin_search(eb, key, level, slot);
837}
838
839static void root_add_used(struct btrfs_root *root, u32 size)
840{
841 spin_lock(&root->accounting_lock);
842 btrfs_set_root_used(&root->root_item,
843 btrfs_root_used(&root->root_item) + size);
844 spin_unlock(&root->accounting_lock);
845}
846
847static void root_sub_used(struct btrfs_root *root, u32 size)
848{
849 spin_lock(&root->accounting_lock);
850 btrfs_set_root_used(&root->root_item,
851 btrfs_root_used(&root->root_item) - size);
852 spin_unlock(&root->accounting_lock);
853}
854
855/* given a node and slot number, this reads the blocks it points to. The
856 * extent buffer is returned with a reference taken (but unlocked).
857 * NULL is returned on error.
858 */
859static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root,
860 struct extent_buffer *parent, int slot)
861{
862 int level = btrfs_header_level(parent);
863 if (slot < 0)
864 return NULL;
865 if (slot >= btrfs_header_nritems(parent))
866 return NULL;
867
868 BUG_ON(level == 0);
869
870 return read_tree_block(root, btrfs_node_blockptr(parent, slot),
871 btrfs_level_size(root, level - 1),
872 btrfs_node_ptr_generation(parent, slot));
873}
874
875/*
876 * node level balancing, used to make sure nodes are in proper order for
877 * item deletion. We balance from the top down, so we have to make sure
878 * that a deletion won't leave an node completely empty later on.
879 */
880static noinline int balance_level(struct btrfs_trans_handle *trans,
881 struct btrfs_root *root,
882 struct btrfs_path *path, int level)
883{
884 struct extent_buffer *right = NULL;
885 struct extent_buffer *mid;
886 struct extent_buffer *left = NULL;
887 struct extent_buffer *parent = NULL;
888 int ret = 0;
889 int wret;
890 int pslot;
891 int orig_slot = path->slots[level];
892 u64 orig_ptr;
893
894 if (level == 0)
895 return 0;
896
897 mid = path->nodes[level];
898
899 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
900 path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
901 WARN_ON(btrfs_header_generation(mid) != trans->transid);
902
903 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
904
905 if (level < BTRFS_MAX_LEVEL - 1)
906 parent = path->nodes[level + 1];
907 pslot = path->slots[level + 1];
908
909 /*
910 * deal with the case where there is only one pointer in the root
911 * by promoting the node below to a root
912 */
913 if (!parent) {
914 struct extent_buffer *child;
915
916 if (btrfs_header_nritems(mid) != 1)
917 return 0;
918
919 /* promote the child to a root */
920 child = read_node_slot(root, mid, 0);
921 BUG_ON(!child);
922 btrfs_tree_lock(child);
923 btrfs_set_lock_blocking(child);
924 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
925 if (ret) {
926 btrfs_tree_unlock(child);
927 free_extent_buffer(child);
928 goto enospc;
929 }
930
931 rcu_assign_pointer(root->node, child);
932
933 add_root_to_dirty_list(root);
934 btrfs_tree_unlock(child);
935
936 path->locks[level] = 0;
937 path->nodes[level] = NULL;
938 clean_tree_block(trans, root, mid);
939 btrfs_tree_unlock(mid);
940 /* once for the path */
941 free_extent_buffer(mid);
942
943 root_sub_used(root, mid->len);
944 btrfs_free_tree_block(trans, root, mid, 0, 1);
945 /* once for the root ptr */
946 free_extent_buffer(mid);
947 return 0;
948 }
949 if (btrfs_header_nritems(mid) >
950 BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
951 return 0;
952
953 btrfs_header_nritems(mid);
954
955 left = read_node_slot(root, parent, pslot - 1);
956 if (left) {
957 btrfs_tree_lock(left);
958 btrfs_set_lock_blocking(left);
959 wret = btrfs_cow_block(trans, root, left,
960 parent, pslot - 1, &left);
961 if (wret) {
962 ret = wret;
963 goto enospc;
964 }
965 }
966 right = read_node_slot(root, parent, pslot + 1);
967 if (right) {
968 btrfs_tree_lock(right);
969 btrfs_set_lock_blocking(right);
970 wret = btrfs_cow_block(trans, root, right,
971 parent, pslot + 1, &right);
972 if (wret) {
973 ret = wret;
974 goto enospc;
975 }
976 }
977
978 /* first, try to make some room in the middle buffer */
979 if (left) {
980 orig_slot += btrfs_header_nritems(left);
981 wret = push_node_left(trans, root, left, mid, 1);
982 if (wret < 0)
983 ret = wret;
984 btrfs_header_nritems(mid);
985 }
986
987 /*
988 * then try to empty the right most buffer into the middle
989 */
990 if (right) {
991 wret = push_node_left(trans, root, mid, right, 1);
992 if (wret < 0 && wret != -ENOSPC)
993 ret = wret;
994 if (btrfs_header_nritems(right) == 0) {
995 clean_tree_block(trans, root, right);
996 btrfs_tree_unlock(right);
997 wret = del_ptr(trans, root, path, level + 1, pslot +
998 1);
999 if (wret)
1000 ret = wret;
1001 root_sub_used(root, right->len);
1002 btrfs_free_tree_block(trans, root, right, 0, 1);
1003 free_extent_buffer(right);
1004 right = NULL;
1005 } else {
1006 struct btrfs_disk_key right_key;
1007 btrfs_node_key(right, &right_key, 0);
1008 btrfs_set_node_key(parent, &right_key, pslot + 1);
1009 btrfs_mark_buffer_dirty(parent);
1010 }
1011 }
1012 if (btrfs_header_nritems(mid) == 1) {
1013 /*
1014 * we're not allowed to leave a node with one item in the
1015 * tree during a delete. A deletion from lower in the tree
1016 * could try to delete the only pointer in this node.
1017 * So, pull some keys from the left.
1018 * There has to be a left pointer at this point because
1019 * otherwise we would have pulled some pointers from the
1020 * right
1021 */
1022 BUG_ON(!left);
1023 wret = balance_node_right(trans, root, mid, left);
1024 if (wret < 0) {
1025 ret = wret;
1026 goto enospc;
1027 }
1028 if (wret == 1) {
1029 wret = push_node_left(trans, root, left, mid, 1);
1030 if (wret < 0)
1031 ret = wret;
1032 }
1033 BUG_ON(wret == 1);
1034 }
1035 if (btrfs_header_nritems(mid) == 0) {
1036 clean_tree_block(trans, root, mid);
1037 btrfs_tree_unlock(mid);
1038 wret = del_ptr(trans, root, path, level + 1, pslot);
1039 if (wret)
1040 ret = wret;
1041 root_sub_used(root, mid->len);
1042 btrfs_free_tree_block(trans, root, mid, 0, 1);
1043 free_extent_buffer(mid);
1044 mid = NULL;
1045 } else {
1046 /* update the parent key to reflect our changes */
1047 struct btrfs_disk_key mid_key;
1048 btrfs_node_key(mid, &mid_key, 0);
1049 btrfs_set_node_key(parent, &mid_key, pslot);
1050 btrfs_mark_buffer_dirty(parent);
1051 }
1052
1053 /* update the path */
1054 if (left) {
1055 if (btrfs_header_nritems(left) > orig_slot) {
1056 extent_buffer_get(left);
1057 /* left was locked after cow */
1058 path->nodes[level] = left;
1059 path->slots[level + 1] -= 1;
1060 path->slots[level] = orig_slot;
1061 if (mid) {
1062 btrfs_tree_unlock(mid);
1063 free_extent_buffer(mid);
1064 }
1065 } else {
1066 orig_slot -= btrfs_header_nritems(left);
1067 path->slots[level] = orig_slot;
1068 }
1069 }
1070 /* double check we haven't messed things up */
1071 if (orig_ptr !=
1072 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1073 BUG();
1074enospc:
1075 if (right) {
1076 btrfs_tree_unlock(right);
1077 free_extent_buffer(right);
1078 }
1079 if (left) {
1080 if (path->nodes[level] != left)
1081 btrfs_tree_unlock(left);
1082 free_extent_buffer(left);
1083 }
1084 return ret;
1085}
1086
1087/* Node balancing for insertion. Here we only split or push nodes around
1088 * when they are completely full. This is also done top down, so we
1089 * have to be pessimistic.
1090 */
1091static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1092 struct btrfs_root *root,
1093 struct btrfs_path *path, int level)
1094{
1095 struct extent_buffer *right = NULL;
1096 struct extent_buffer *mid;
1097 struct extent_buffer *left = NULL;
1098 struct extent_buffer *parent = NULL;
1099 int ret = 0;
1100 int wret;
1101 int pslot;
1102 int orig_slot = path->slots[level];
1103
1104 if (level == 0)
1105 return 1;
1106
1107 mid = path->nodes[level];
1108 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1109
1110 if (level < BTRFS_MAX_LEVEL - 1)
1111 parent = path->nodes[level + 1];
1112 pslot = path->slots[level + 1];
1113
1114 if (!parent)
1115 return 1;
1116
1117 left = read_node_slot(root, parent, pslot - 1);
1118
1119 /* first, try to make some room in the middle buffer */
1120 if (left) {
1121 u32 left_nr;
1122
1123 btrfs_tree_lock(left);
1124 btrfs_set_lock_blocking(left);
1125
1126 left_nr = btrfs_header_nritems(left);
1127 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1128 wret = 1;
1129 } else {
1130 ret = btrfs_cow_block(trans, root, left, parent,
1131 pslot - 1, &left);
1132 if (ret)
1133 wret = 1;
1134 else {
1135 wret = push_node_left(trans, root,
1136 left, mid, 0);
1137 }
1138 }
1139 if (wret < 0)
1140 ret = wret;
1141 if (wret == 0) {
1142 struct btrfs_disk_key disk_key;
1143 orig_slot += left_nr;
1144 btrfs_node_key(mid, &disk_key, 0);
1145 btrfs_set_node_key(parent, &disk_key, pslot);
1146 btrfs_mark_buffer_dirty(parent);
1147 if (btrfs_header_nritems(left) > orig_slot) {
1148 path->nodes[level] = left;
1149 path->slots[level + 1] -= 1;
1150 path->slots[level] = orig_slot;
1151 btrfs_tree_unlock(mid);
1152 free_extent_buffer(mid);
1153 } else {
1154 orig_slot -=
1155 btrfs_header_nritems(left);
1156 path->slots[level] = orig_slot;
1157 btrfs_tree_unlock(left);
1158 free_extent_buffer(left);
1159 }
1160 return 0;
1161 }
1162 btrfs_tree_unlock(left);
1163 free_extent_buffer(left);
1164 }
1165 right = read_node_slot(root, parent, pslot + 1);
1166
1167 /*
1168 * then try to empty the right most buffer into the middle
1169 */
1170 if (right) {
1171 u32 right_nr;
1172
1173 btrfs_tree_lock(right);
1174 btrfs_set_lock_blocking(right);
1175
1176 right_nr = btrfs_header_nritems(right);
1177 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1178 wret = 1;
1179 } else {
1180 ret = btrfs_cow_block(trans, root, right,
1181 parent, pslot + 1,
1182 &right);
1183 if (ret)
1184 wret = 1;
1185 else {
1186 wret = balance_node_right(trans, root,
1187 right, mid);
1188 }
1189 }
1190 if (wret < 0)
1191 ret = wret;
1192 if (wret == 0) {
1193 struct btrfs_disk_key disk_key;
1194
1195 btrfs_node_key(right, &disk_key, 0);
1196 btrfs_set_node_key(parent, &disk_key, pslot + 1);
1197 btrfs_mark_buffer_dirty(parent);
1198
1199 if (btrfs_header_nritems(mid) <= orig_slot) {
1200 path->nodes[level] = right;
1201 path->slots[level + 1] += 1;
1202 path->slots[level] = orig_slot -
1203 btrfs_header_nritems(mid);
1204 btrfs_tree_unlock(mid);
1205 free_extent_buffer(mid);
1206 } else {
1207 btrfs_tree_unlock(right);
1208 free_extent_buffer(right);
1209 }
1210 return 0;
1211 }
1212 btrfs_tree_unlock(right);
1213 free_extent_buffer(right);
1214 }
1215 return 1;
1216}
1217
1218/*
1219 * readahead one full node of leaves, finding things that are close
1220 * to the block in 'slot', and triggering ra on them.
1221 */
1222static void reada_for_search(struct btrfs_root *root,
1223 struct btrfs_path *path,
1224 int level, int slot, u64 objectid)
1225{
1226 struct extent_buffer *node;
1227 struct btrfs_disk_key disk_key;
1228 u32 nritems;
1229 u64 search;
1230 u64 target;
1231 u64 nread = 0;
1232 u64 gen;
1233 int direction = path->reada;
1234 struct extent_buffer *eb;
1235 u32 nr;
1236 u32 blocksize;
1237 u32 nscan = 0;
1238
1239 if (level != 1)
1240 return;
1241
1242 if (!path->nodes[level])
1243 return;
1244
1245 node = path->nodes[level];
1246
1247 search = btrfs_node_blockptr(node, slot);
1248 blocksize = btrfs_level_size(root, level - 1);
1249 eb = btrfs_find_tree_block(root, search, blocksize);
1250 if (eb) {
1251 free_extent_buffer(eb);
1252 return;
1253 }
1254
1255 target = search;
1256
1257 nritems = btrfs_header_nritems(node);
1258 nr = slot;
1259
1260 while (1) {
1261 if (direction < 0) {
1262 if (nr == 0)
1263 break;
1264 nr--;
1265 } else if (direction > 0) {
1266 nr++;
1267 if (nr >= nritems)
1268 break;
1269 }
1270 if (path->reada < 0 && objectid) {
1271 btrfs_node_key(node, &disk_key, nr);
1272 if (btrfs_disk_key_objectid(&disk_key) != objectid)
1273 break;
1274 }
1275 search = btrfs_node_blockptr(node, nr);
1276 if ((search <= target && target - search <= 65536) ||
1277 (search > target && search - target <= 65536)) {
1278 gen = btrfs_node_ptr_generation(node, nr);
1279 readahead_tree_block(root, search, blocksize, gen);
1280 nread += blocksize;
1281 }
1282 nscan++;
1283 if ((nread > 65536 || nscan > 32))
1284 break;
1285 }
1286}
1287
1288/*
1289 * returns -EAGAIN if it had to drop the path, or zero if everything was in
1290 * cache
1291 */
1292static noinline int reada_for_balance(struct btrfs_root *root,
1293 struct btrfs_path *path, int level)
1294{
1295 int slot;
1296 int nritems;
1297 struct extent_buffer *parent;
1298 struct extent_buffer *eb;
1299 u64 gen;
1300 u64 block1 = 0;
1301 u64 block2 = 0;
1302 int ret = 0;
1303 int blocksize;
1304
1305 parent = path->nodes[level + 1];
1306 if (!parent)
1307 return 0;
1308
1309 nritems = btrfs_header_nritems(parent);
1310 slot = path->slots[level + 1];
1311 blocksize = btrfs_level_size(root, level);
1312
1313 if (slot > 0) {
1314 block1 = btrfs_node_blockptr(parent, slot - 1);
1315 gen = btrfs_node_ptr_generation(parent, slot - 1);
1316 eb = btrfs_find_tree_block(root, block1, blocksize);
1317 if (eb && btrfs_buffer_uptodate(eb, gen))
1318 block1 = 0;
1319 free_extent_buffer(eb);
1320 }
1321 if (slot + 1 < nritems) {
1322 block2 = btrfs_node_blockptr(parent, slot + 1);
1323 gen = btrfs_node_ptr_generation(parent, slot + 1);
1324 eb = btrfs_find_tree_block(root, block2, blocksize);
1325 if (eb && btrfs_buffer_uptodate(eb, gen))
1326 block2 = 0;
1327 free_extent_buffer(eb);
1328 }
1329 if (block1 || block2) {
1330 ret = -EAGAIN;
1331
1332 /* release the whole path */
1333 btrfs_release_path(path);
1334
1335 /* read the blocks */
1336 if (block1)
1337 readahead_tree_block(root, block1, blocksize, 0);
1338 if (block2)
1339 readahead_tree_block(root, block2, blocksize, 0);
1340
1341 if (block1) {
1342 eb = read_tree_block(root, block1, blocksize, 0);
1343 free_extent_buffer(eb);
1344 }
1345 if (block2) {
1346 eb = read_tree_block(root, block2, blocksize, 0);
1347 free_extent_buffer(eb);
1348 }
1349 }
1350 return ret;
1351}
1352
1353
1354/*
1355 * when we walk down the tree, it is usually safe to unlock the higher layers
1356 * in the tree. The exceptions are when our path goes through slot 0, because
1357 * operations on the tree might require changing key pointers higher up in the
1358 * tree.
1359 *
1360 * callers might also have set path->keep_locks, which tells this code to keep
1361 * the lock if the path points to the last slot in the block. This is part of
1362 * walking through the tree, and selecting the next slot in the higher block.
1363 *
1364 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
1365 * if lowest_unlock is 1, level 0 won't be unlocked
1366 */
1367static noinline void unlock_up(struct btrfs_path *path, int level,
1368 int lowest_unlock)
1369{
1370 int i;
1371 int skip_level = level;
1372 int no_skips = 0;
1373 struct extent_buffer *t;
1374
1375 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1376 if (!path->nodes[i])
1377 break;
1378 if (!path->locks[i])
1379 break;
1380 if (!no_skips && path->slots[i] == 0) {
1381 skip_level = i + 1;
1382 continue;
1383 }
1384 if (!no_skips && path->keep_locks) {
1385 u32 nritems;
1386 t = path->nodes[i];
1387 nritems = btrfs_header_nritems(t);
1388 if (nritems < 1 || path->slots[i] >= nritems - 1) {
1389 skip_level = i + 1;
1390 continue;
1391 }
1392 }
1393 if (skip_level < i && i >= lowest_unlock)
1394 no_skips = 1;
1395
1396 t = path->nodes[i];
1397 if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
1398 btrfs_tree_unlock_rw(t, path->locks[i]);
1399 path->locks[i] = 0;
1400 }
1401 }
1402}
1403
1404/*
1405 * This releases any locks held in the path starting at level and
1406 * going all the way up to the root.
1407 *
1408 * btrfs_search_slot will keep the lock held on higher nodes in a few
1409 * corner cases, such as COW of the block at slot zero in the node. This
1410 * ignores those rules, and it should only be called when there are no
1411 * more updates to be done higher up in the tree.
1412 */
1413noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
1414{
1415 int i;
1416
1417 if (path->keep_locks)
1418 return;
1419
1420 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1421 if (!path->nodes[i])
1422 continue;
1423 if (!path->locks[i])
1424 continue;
1425 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
1426 path->locks[i] = 0;
1427 }
1428}
1429
1430/*
1431 * helper function for btrfs_search_slot. The goal is to find a block
1432 * in cache without setting the path to blocking. If we find the block
1433 * we return zero and the path is unchanged.
1434 *
1435 * If we can't find the block, we set the path blocking and do some
1436 * reada. -EAGAIN is returned and the search must be repeated.
1437 */
1438static int
1439read_block_for_search(struct btrfs_trans_handle *trans,
1440 struct btrfs_root *root, struct btrfs_path *p,
1441 struct extent_buffer **eb_ret, int level, int slot,
1442 struct btrfs_key *key)
1443{
1444 u64 blocknr;
1445 u64 gen;
1446 u32 blocksize;
1447 struct extent_buffer *b = *eb_ret;
1448 struct extent_buffer *tmp;
1449 int ret;
1450
1451 blocknr = btrfs_node_blockptr(b, slot);
1452 gen = btrfs_node_ptr_generation(b, slot);
1453 blocksize = btrfs_level_size(root, level - 1);
1454
1455 tmp = btrfs_find_tree_block(root, blocknr, blocksize);
1456 if (tmp) {
1457 if (btrfs_buffer_uptodate(tmp, 0)) {
1458 if (btrfs_buffer_uptodate(tmp, gen)) {
1459 /*
1460 * we found an up to date block without
1461 * sleeping, return
1462 * right away
1463 */
1464 *eb_ret = tmp;
1465 return 0;
1466 }
1467 /* the pages were up to date, but we failed
1468 * the generation number check. Do a full
1469 * read for the generation number that is correct.
1470 * We must do this without dropping locks so
1471 * we can trust our generation number
1472 */
1473 free_extent_buffer(tmp);
1474 btrfs_set_path_blocking(p);
1475
1476 tmp = read_tree_block(root, blocknr, blocksize, gen);
1477 if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
1478 *eb_ret = tmp;
1479 return 0;
1480 }
1481 free_extent_buffer(tmp);
1482 btrfs_release_path(p);
1483 return -EIO;
1484 }
1485 }
1486
1487 /*
1488 * reduce lock contention at high levels
1489 * of the btree by dropping locks before
1490 * we read. Don't release the lock on the current
1491 * level because we need to walk this node to figure
1492 * out which blocks to read.
1493 */
1494 btrfs_unlock_up_safe(p, level + 1);
1495 btrfs_set_path_blocking(p);
1496
1497 free_extent_buffer(tmp);
1498 if (p->reada)
1499 reada_for_search(root, p, level, slot, key->objectid);
1500
1501 btrfs_release_path(p);
1502
1503 ret = -EAGAIN;
1504 tmp = read_tree_block(root, blocknr, blocksize, 0);
1505 if (tmp) {
1506 /*
1507 * If the read above didn't mark this buffer up to date,
1508 * it will never end up being up to date. Set ret to EIO now
1509 * and give up so that our caller doesn't loop forever
1510 * on our EAGAINs.
1511 */
1512 if (!btrfs_buffer_uptodate(tmp, 0))
1513 ret = -EIO;
1514 free_extent_buffer(tmp);
1515 }
1516 return ret;
1517}
1518
1519/*
1520 * helper function for btrfs_search_slot. This does all of the checks
1521 * for node-level blocks and does any balancing required based on
1522 * the ins_len.
1523 *
1524 * If no extra work was required, zero is returned. If we had to
1525 * drop the path, -EAGAIN is returned and btrfs_search_slot must
1526 * start over
1527 */
1528static int
1529setup_nodes_for_search(struct btrfs_trans_handle *trans,
1530 struct btrfs_root *root, struct btrfs_path *p,
1531 struct extent_buffer *b, int level, int ins_len,
1532 int *write_lock_level)
1533{
1534 int ret;
1535 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
1536 BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
1537 int sret;
1538
1539 if (*write_lock_level < level + 1) {
1540 *write_lock_level = level + 1;
1541 btrfs_release_path(p);
1542 goto again;
1543 }
1544
1545 sret = reada_for_balance(root, p, level);
1546 if (sret)
1547 goto again;
1548
1549 btrfs_set_path_blocking(p);
1550 sret = split_node(trans, root, p, level);
1551 btrfs_clear_path_blocking(p, NULL, 0);
1552
1553 BUG_ON(sret > 0);
1554 if (sret) {
1555 ret = sret;
1556 goto done;
1557 }
1558 b = p->nodes[level];
1559 } else if (ins_len < 0 && btrfs_header_nritems(b) <
1560 BTRFS_NODEPTRS_PER_BLOCK(root) / 2) {
1561 int sret;
1562
1563 if (*write_lock_level < level + 1) {
1564 *write_lock_level = level + 1;
1565 btrfs_release_path(p);
1566 goto again;
1567 }
1568
1569 sret = reada_for_balance(root, p, level);
1570 if (sret)
1571 goto again;
1572
1573 btrfs_set_path_blocking(p);
1574 sret = balance_level(trans, root, p, level);
1575 btrfs_clear_path_blocking(p, NULL, 0);
1576
1577 if (sret) {
1578 ret = sret;
1579 goto done;
1580 }
1581 b = p->nodes[level];
1582 if (!b) {
1583 btrfs_release_path(p);
1584 goto again;
1585 }
1586 BUG_ON(btrfs_header_nritems(b) == 1);
1587 }
1588 return 0;
1589
1590again:
1591 ret = -EAGAIN;
1592done:
1593 return ret;
1594}
1595
1596/*
1597 * look for key in the tree. path is filled in with nodes along the way
1598 * if key is found, we return zero and you can find the item in the leaf
1599 * level of the path (level 0)
1600 *
1601 * If the key isn't found, the path points to the slot where it should
1602 * be inserted, and 1 is returned. If there are other errors during the
1603 * search a negative error number is returned.
1604 *
1605 * if ins_len > 0, nodes and leaves will be split as we walk down the
1606 * tree. if ins_len < 0, nodes will be merged as we walk down the tree (if
1607 * possible)
1608 */
1609int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
1610 *root, struct btrfs_key *key, struct btrfs_path *p, int
1611 ins_len, int cow)
1612{
1613 struct extent_buffer *b;
1614 int slot;
1615 int ret;
1616 int err;
1617 int level;
1618 int lowest_unlock = 1;
1619 int root_lock;
1620 /* everything at write_lock_level or lower must be write locked */
1621 int write_lock_level = 0;
1622 u8 lowest_level = 0;
1623
1624 lowest_level = p->lowest_level;
1625 WARN_ON(lowest_level && ins_len > 0);
1626 WARN_ON(p->nodes[0] != NULL);
1627
1628 if (ins_len < 0) {
1629 lowest_unlock = 2;
1630
1631 /* when we are removing items, we might have to go up to level
1632 * two as we update tree pointers Make sure we keep write
1633 * for those levels as well
1634 */
1635 write_lock_level = 2;
1636 } else if (ins_len > 0) {
1637 /*
1638 * for inserting items, make sure we have a write lock on
1639 * level 1 so we can update keys
1640 */
1641 write_lock_level = 1;
1642 }
1643
1644 if (!cow)
1645 write_lock_level = -1;
1646
1647 if (cow && (p->keep_locks || p->lowest_level))
1648 write_lock_level = BTRFS_MAX_LEVEL;
1649
1650again:
1651 /*
1652 * we try very hard to do read locks on the root
1653 */
1654 root_lock = BTRFS_READ_LOCK;
1655 level = 0;
1656 if (p->search_commit_root) {
1657 /*
1658 * the commit roots are read only
1659 * so we always do read locks
1660 */
1661 b = root->commit_root;
1662 extent_buffer_get(b);
1663 level = btrfs_header_level(b);
1664 if (!p->skip_locking)
1665 btrfs_tree_read_lock(b);
1666 } else {
1667 if (p->skip_locking) {
1668 b = btrfs_root_node(root);
1669 level = btrfs_header_level(b);
1670 } else {
1671 /* we don't know the level of the root node
1672 * until we actually have it read locked
1673 */
1674 b = btrfs_read_lock_root_node(root);
1675 level = btrfs_header_level(b);
1676 if (level <= write_lock_level) {
1677 /* whoops, must trade for write lock */
1678 btrfs_tree_read_unlock(b);
1679 free_extent_buffer(b);
1680 b = btrfs_lock_root_node(root);
1681 root_lock = BTRFS_WRITE_LOCK;
1682
1683 /* the level might have changed, check again */
1684 level = btrfs_header_level(b);
1685 }
1686 }
1687 }
1688 p->nodes[level] = b;
1689 if (!p->skip_locking)
1690 p->locks[level] = root_lock;
1691
1692 while (b) {
1693 level = btrfs_header_level(b);
1694
1695 /*
1696 * setup the path here so we can release it under lock
1697 * contention with the cow code
1698 */
1699 if (cow) {
1700 /*
1701 * if we don't really need to cow this block
1702 * then we don't want to set the path blocking,
1703 * so we test it here
1704 */
1705 if (!should_cow_block(trans, root, b))
1706 goto cow_done;
1707
1708 btrfs_set_path_blocking(p);
1709
1710 /*
1711 * must have write locks on this node and the
1712 * parent
1713 */
1714 if (level + 1 > write_lock_level) {
1715 write_lock_level = level + 1;
1716 btrfs_release_path(p);
1717 goto again;
1718 }
1719
1720 err = btrfs_cow_block(trans, root, b,
1721 p->nodes[level + 1],
1722 p->slots[level + 1], &b);
1723 if (err) {
1724 ret = err;
1725 goto done;
1726 }
1727 }
1728cow_done:
1729 BUG_ON(!cow && ins_len);
1730
1731 p->nodes[level] = b;
1732 btrfs_clear_path_blocking(p, NULL, 0);
1733
1734 /*
1735 * we have a lock on b and as long as we aren't changing
1736 * the tree, there is no way to for the items in b to change.
1737 * It is safe to drop the lock on our parent before we
1738 * go through the expensive btree search on b.
1739 *
1740 * If cow is true, then we might be changing slot zero,
1741 * which may require changing the parent. So, we can't
1742 * drop the lock until after we know which slot we're
1743 * operating on.
1744 */
1745 if (!cow)
1746 btrfs_unlock_up_safe(p, level + 1);
1747
1748 ret = bin_search(b, key, level, &slot);
1749
1750 if (level != 0) {
1751 int dec = 0;
1752 if (ret && slot > 0) {
1753 dec = 1;
1754 slot -= 1;
1755 }
1756 p->slots[level] = slot;
1757 err = setup_nodes_for_search(trans, root, p, b, level,
1758 ins_len, &write_lock_level);
1759 if (err == -EAGAIN)
1760 goto again;
1761 if (err) {
1762 ret = err;
1763 goto done;
1764 }
1765 b = p->nodes[level];
1766 slot = p->slots[level];
1767
1768 /*
1769 * slot 0 is special, if we change the key
1770 * we have to update the parent pointer
1771 * which means we must have a write lock
1772 * on the parent
1773 */
1774 if (slot == 0 && cow &&
1775 write_lock_level < level + 1) {
1776 write_lock_level = level + 1;
1777 btrfs_release_path(p);
1778 goto again;
1779 }
1780
1781 unlock_up(p, level, lowest_unlock);
1782
1783 if (level == lowest_level) {
1784 if (dec)
1785 p->slots[level]++;
1786 goto done;
1787 }
1788
1789 err = read_block_for_search(trans, root, p,
1790 &b, level, slot, key);
1791 if (err == -EAGAIN)
1792 goto again;
1793 if (err) {
1794 ret = err;
1795 goto done;
1796 }
1797
1798 if (!p->skip_locking) {
1799 level = btrfs_header_level(b);
1800 if (level <= write_lock_level) {
1801 err = btrfs_try_tree_write_lock(b);
1802 if (!err) {
1803 btrfs_set_path_blocking(p);
1804 btrfs_tree_lock(b);
1805 btrfs_clear_path_blocking(p, b,
1806 BTRFS_WRITE_LOCK);
1807 }
1808 p->locks[level] = BTRFS_WRITE_LOCK;
1809 } else {
1810 err = btrfs_try_tree_read_lock(b);
1811 if (!err) {
1812 btrfs_set_path_blocking(p);
1813 btrfs_tree_read_lock(b);
1814 btrfs_clear_path_blocking(p, b,
1815 BTRFS_READ_LOCK);
1816 }
1817 p->locks[level] = BTRFS_READ_LOCK;
1818 }
1819 p->nodes[level] = b;
1820 }
1821 } else {
1822 p->slots[level] = slot;
1823 if (ins_len > 0 &&
1824 btrfs_leaf_free_space(root, b) < ins_len) {
1825 if (write_lock_level < 1) {
1826 write_lock_level = 1;
1827 btrfs_release_path(p);
1828 goto again;
1829 }
1830
1831 btrfs_set_path_blocking(p);
1832 err = split_leaf(trans, root, key,
1833 p, ins_len, ret == 0);
1834 btrfs_clear_path_blocking(p, NULL, 0);
1835
1836 BUG_ON(err > 0);
1837 if (err) {
1838 ret = err;
1839 goto done;
1840 }
1841 }
1842 if (!p->search_for_split)
1843 unlock_up(p, level, lowest_unlock);
1844 goto done;
1845 }
1846 }
1847 ret = 1;
1848done:
1849 /*
1850 * we don't really know what they plan on doing with the path
1851 * from here on, so for now just mark it as blocking
1852 */
1853 if (!p->leave_spinning)
1854 btrfs_set_path_blocking(p);
1855 if (ret < 0)
1856 btrfs_release_path(p);
1857 return ret;
1858}
1859
1860/*
1861 * adjust the pointers going up the tree, starting at level
1862 * making sure the right key of each node is points to 'key'.
1863 * This is used after shifting pointers to the left, so it stops
1864 * fixing up pointers when a given leaf/node is not in slot 0 of the
1865 * higher levels
1866 *
1867 * If this fails to write a tree block, it returns -1, but continues
1868 * fixing up the blocks in ram so the tree is consistent.
1869 */
1870static int fixup_low_keys(struct btrfs_trans_handle *trans,
1871 struct btrfs_root *root, struct btrfs_path *path,
1872 struct btrfs_disk_key *key, int level)
1873{
1874 int i;
1875 int ret = 0;
1876 struct extent_buffer *t;
1877
1878 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1879 int tslot = path->slots[i];
1880 if (!path->nodes[i])
1881 break;
1882 t = path->nodes[i];
1883 btrfs_set_node_key(t, key, tslot);
1884 btrfs_mark_buffer_dirty(path->nodes[i]);
1885 if (tslot != 0)
1886 break;
1887 }
1888 return ret;
1889}
1890
1891/*
1892 * update item key.
1893 *
1894 * This function isn't completely safe. It's the caller's responsibility
1895 * that the new key won't break the order
1896 */
1897int btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
1898 struct btrfs_root *root, struct btrfs_path *path,
1899 struct btrfs_key *new_key)
1900{
1901 struct btrfs_disk_key disk_key;
1902 struct extent_buffer *eb;
1903 int slot;
1904
1905 eb = path->nodes[0];
1906 slot = path->slots[0];
1907 if (slot > 0) {
1908 btrfs_item_key(eb, &disk_key, slot - 1);
1909 if (comp_keys(&disk_key, new_key) >= 0)
1910 return -1;
1911 }
1912 if (slot < btrfs_header_nritems(eb) - 1) {
1913 btrfs_item_key(eb, &disk_key, slot + 1);
1914 if (comp_keys(&disk_key, new_key) <= 0)
1915 return -1;
1916 }
1917
1918 btrfs_cpu_key_to_disk(&disk_key, new_key);
1919 btrfs_set_item_key(eb, &disk_key, slot);
1920 btrfs_mark_buffer_dirty(eb);
1921 if (slot == 0)
1922 fixup_low_keys(trans, root, path, &disk_key, 1);
1923 return 0;
1924}
1925
1926/*
1927 * try to push data from one node into the next node left in the
1928 * tree.
1929 *
1930 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1931 * error, and > 0 if there was no room in the left hand block.
1932 */
1933static int push_node_left(struct btrfs_trans_handle *trans,
1934 struct btrfs_root *root, struct extent_buffer *dst,
1935 struct extent_buffer *src, int empty)
1936{
1937 int push_items = 0;
1938 int src_nritems;
1939 int dst_nritems;
1940 int ret = 0;
1941
1942 src_nritems = btrfs_header_nritems(src);
1943 dst_nritems = btrfs_header_nritems(dst);
1944 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1945 WARN_ON(btrfs_header_generation(src) != trans->transid);
1946 WARN_ON(btrfs_header_generation(dst) != trans->transid);
1947
1948 if (!empty && src_nritems <= 8)
1949 return 1;
1950
1951 if (push_items <= 0)
1952 return 1;
1953
1954 if (empty) {
1955 push_items = min(src_nritems, push_items);
1956 if (push_items < src_nritems) {
1957 /* leave at least 8 pointers in the node if
1958 * we aren't going to empty it
1959 */
1960 if (src_nritems - push_items < 8) {
1961 if (push_items <= 8)
1962 return 1;
1963 push_items -= 8;
1964 }
1965 }
1966 } else
1967 push_items = min(src_nritems - 8, push_items);
1968
1969 copy_extent_buffer(dst, src,
1970 btrfs_node_key_ptr_offset(dst_nritems),
1971 btrfs_node_key_ptr_offset(0),
1972 push_items * sizeof(struct btrfs_key_ptr));
1973
1974 if (push_items < src_nritems) {
1975 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1976 btrfs_node_key_ptr_offset(push_items),
1977 (src_nritems - push_items) *
1978 sizeof(struct btrfs_key_ptr));
1979 }
1980 btrfs_set_header_nritems(src, src_nritems - push_items);
1981 btrfs_set_header_nritems(dst, dst_nritems + push_items);
1982 btrfs_mark_buffer_dirty(src);
1983 btrfs_mark_buffer_dirty(dst);
1984
1985 return ret;
1986}
1987
1988/*
1989 * try to push data from one node into the next node right in the
1990 * tree.
1991 *
1992 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1993 * error, and > 0 if there was no room in the right hand block.
1994 *
1995 * this will only push up to 1/2 the contents of the left node over
1996 */
1997static int balance_node_right(struct btrfs_trans_handle *trans,
1998 struct btrfs_root *root,
1999 struct extent_buffer *dst,
2000 struct extent_buffer *src)
2001{
2002 int push_items = 0;
2003 int max_push;
2004 int src_nritems;
2005 int dst_nritems;
2006 int ret = 0;
2007
2008 WARN_ON(btrfs_header_generation(src) != trans->transid);
2009 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2010
2011 src_nritems = btrfs_header_nritems(src);
2012 dst_nritems = btrfs_header_nritems(dst);
2013 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
2014 if (push_items <= 0)
2015 return 1;
2016
2017 if (src_nritems < 4)
2018 return 1;
2019
2020 max_push = src_nritems / 2 + 1;
2021 /* don't try to empty the node */
2022 if (max_push >= src_nritems)
2023 return 1;
2024
2025 if (max_push < push_items)
2026 push_items = max_push;
2027
2028 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
2029 btrfs_node_key_ptr_offset(0),
2030 (dst_nritems) *
2031 sizeof(struct btrfs_key_ptr));
2032
2033 copy_extent_buffer(dst, src,
2034 btrfs_node_key_ptr_offset(0),
2035 btrfs_node_key_ptr_offset(src_nritems - push_items),
2036 push_items * sizeof(struct btrfs_key_ptr));
2037
2038 btrfs_set_header_nritems(src, src_nritems - push_items);
2039 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2040
2041 btrfs_mark_buffer_dirty(src);
2042 btrfs_mark_buffer_dirty(dst);
2043
2044 return ret;
2045}
2046
2047/*
2048 * helper function to insert a new root level in the tree.
2049 * A new node is allocated, and a single item is inserted to
2050 * point to the existing root
2051 *
2052 * returns zero on success or < 0 on failure.
2053 */
2054static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2055 struct btrfs_root *root,
2056 struct btrfs_path *path, int level)
2057{
2058 u64 lower_gen;
2059 struct extent_buffer *lower;
2060 struct extent_buffer *c;
2061 struct extent_buffer *old;
2062 struct btrfs_disk_key lower_key;
2063
2064 BUG_ON(path->nodes[level]);
2065 BUG_ON(path->nodes[level-1] != root->node);
2066
2067 lower = path->nodes[level-1];
2068 if (level == 1)
2069 btrfs_item_key(lower, &lower_key, 0);
2070 else
2071 btrfs_node_key(lower, &lower_key, 0);
2072
2073 c = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
2074 root->root_key.objectid, &lower_key,
2075 level, root->node->start, 0);
2076 if (IS_ERR(c))
2077 return PTR_ERR(c);
2078
2079 root_add_used(root, root->nodesize);
2080
2081 memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
2082 btrfs_set_header_nritems(c, 1);
2083 btrfs_set_header_level(c, level);
2084 btrfs_set_header_bytenr(c, c->start);
2085 btrfs_set_header_generation(c, trans->transid);
2086 btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
2087 btrfs_set_header_owner(c, root->root_key.objectid);
2088
2089 write_extent_buffer(c, root->fs_info->fsid,
2090 (unsigned long)btrfs_header_fsid(c),
2091 BTRFS_FSID_SIZE);
2092
2093 write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
2094 (unsigned long)btrfs_header_chunk_tree_uuid(c),
2095 BTRFS_UUID_SIZE);
2096
2097 btrfs_set_node_key(c, &lower_key, 0);
2098 btrfs_set_node_blockptr(c, 0, lower->start);
2099 lower_gen = btrfs_header_generation(lower);
2100 WARN_ON(lower_gen != trans->transid);
2101
2102 btrfs_set_node_ptr_generation(c, 0, lower_gen);
2103
2104 btrfs_mark_buffer_dirty(c);
2105
2106 old = root->node;
2107 rcu_assign_pointer(root->node, c);
2108
2109 /* the super has an extra ref to root->node */
2110 free_extent_buffer(old);
2111
2112 add_root_to_dirty_list(root);
2113 extent_buffer_get(c);
2114 path->nodes[level] = c;
2115 path->locks[level] = BTRFS_WRITE_LOCK;
2116 path->slots[level] = 0;
2117 return 0;
2118}
2119
2120/*
2121 * worker function to insert a single pointer in a node.
2122 * the node should have enough room for the pointer already
2123 *
2124 * slot and level indicate where you want the key to go, and
2125 * blocknr is the block the key points to.
2126 *
2127 * returns zero on success and < 0 on any error
2128 */
2129static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
2130 *root, struct btrfs_path *path, struct btrfs_disk_key
2131 *key, u64 bytenr, int slot, int level)
2132{
2133 struct extent_buffer *lower;
2134 int nritems;
2135
2136 BUG_ON(!path->nodes[level]);
2137 btrfs_assert_tree_locked(path->nodes[level]);
2138 lower = path->nodes[level];
2139 nritems = btrfs_header_nritems(lower);
2140 BUG_ON(slot > nritems);
2141 if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
2142 BUG();
2143 if (slot != nritems) {
2144 memmove_extent_buffer(lower,
2145 btrfs_node_key_ptr_offset(slot + 1),
2146 btrfs_node_key_ptr_offset(slot),
2147 (nritems - slot) * sizeof(struct btrfs_key_ptr));
2148 }
2149 btrfs_set_node_key(lower, key, slot);
2150 btrfs_set_node_blockptr(lower, slot, bytenr);
2151 WARN_ON(trans->transid == 0);
2152 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
2153 btrfs_set_header_nritems(lower, nritems + 1);
2154 btrfs_mark_buffer_dirty(lower);
2155 return 0;
2156}
2157
2158/*
2159 * split the node at the specified level in path in two.
2160 * The path is corrected to point to the appropriate node after the split
2161 *
2162 * Before splitting this tries to make some room in the node by pushing
2163 * left and right, if either one works, it returns right away.
2164 *
2165 * returns 0 on success and < 0 on failure
2166 */
2167static noinline int split_node(struct btrfs_trans_handle *trans,
2168 struct btrfs_root *root,
2169 struct btrfs_path *path, int level)
2170{
2171 struct extent_buffer *c;
2172 struct extent_buffer *split;
2173 struct btrfs_disk_key disk_key;
2174 int mid;
2175 int ret;
2176 int wret;
2177 u32 c_nritems;
2178
2179 c = path->nodes[level];
2180 WARN_ON(btrfs_header_generation(c) != trans->transid);
2181 if (c == root->node) {
2182 /* trying to split the root, lets make a new one */
2183 ret = insert_new_root(trans, root, path, level + 1);
2184 if (ret)
2185 return ret;
2186 } else {
2187 ret = push_nodes_for_insert(trans, root, path, level);
2188 c = path->nodes[level];
2189 if (!ret && btrfs_header_nritems(c) <
2190 BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
2191 return 0;
2192 if (ret < 0)
2193 return ret;
2194 }
2195
2196 c_nritems = btrfs_header_nritems(c);
2197 mid = (c_nritems + 1) / 2;
2198 btrfs_node_key(c, &disk_key, mid);
2199
2200 split = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
2201 root->root_key.objectid,
2202 &disk_key, level, c->start, 0);
2203 if (IS_ERR(split))
2204 return PTR_ERR(split);
2205
2206 root_add_used(root, root->nodesize);
2207
2208 memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header));
2209 btrfs_set_header_level(split, btrfs_header_level(c));
2210 btrfs_set_header_bytenr(split, split->start);
2211 btrfs_set_header_generation(split, trans->transid);
2212 btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
2213 btrfs_set_header_owner(split, root->root_key.objectid);
2214 write_extent_buffer(split, root->fs_info->fsid,
2215 (unsigned long)btrfs_header_fsid(split),
2216 BTRFS_FSID_SIZE);
2217 write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
2218 (unsigned long)btrfs_header_chunk_tree_uuid(split),
2219 BTRFS_UUID_SIZE);
2220
2221
2222 copy_extent_buffer(split, c,
2223 btrfs_node_key_ptr_offset(0),
2224 btrfs_node_key_ptr_offset(mid),
2225 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
2226 btrfs_set_header_nritems(split, c_nritems - mid);
2227 btrfs_set_header_nritems(c, mid);
2228 ret = 0;
2229
2230 btrfs_mark_buffer_dirty(c);
2231 btrfs_mark_buffer_dirty(split);
2232
2233 wret = insert_ptr(trans, root, path, &disk_key, split->start,
2234 path->slots[level + 1] + 1,
2235 level + 1);
2236 if (wret)
2237 ret = wret;
2238
2239 if (path->slots[level] >= mid) {
2240 path->slots[level] -= mid;
2241 btrfs_tree_unlock(c);
2242 free_extent_buffer(c);
2243 path->nodes[level] = split;
2244 path->slots[level + 1] += 1;
2245 } else {
2246 btrfs_tree_unlock(split);
2247 free_extent_buffer(split);
2248 }
2249 return ret;
2250}
2251
2252/*
2253 * how many bytes are required to store the items in a leaf. start
2254 * and nr indicate which items in the leaf to check. This totals up the
2255 * space used both by the item structs and the item data
2256 */
2257static int leaf_space_used(struct extent_buffer *l, int start, int nr)
2258{
2259 int data_len;
2260 int nritems = btrfs_header_nritems(l);
2261 int end = min(nritems, start + nr) - 1;
2262
2263 if (!nr)
2264 return 0;
2265 data_len = btrfs_item_end_nr(l, start);
2266 data_len = data_len - btrfs_item_offset_nr(l, end);
2267 data_len += sizeof(struct btrfs_item) * nr;
2268 WARN_ON(data_len < 0);
2269 return data_len;
2270}
2271
2272/*
2273 * The space between the end of the leaf items and
2274 * the start of the leaf data. IOW, how much room
2275 * the leaf has left for both items and data
2276 */
2277noinline int btrfs_leaf_free_space(struct btrfs_root *root,
2278 struct extent_buffer *leaf)
2279{
2280 int nritems = btrfs_header_nritems(leaf);
2281 int ret;
2282 ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
2283 if (ret < 0) {
2284 printk(KERN_CRIT "leaf free space ret %d, leaf data size %lu, "
2285 "used %d nritems %d\n",
2286 ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
2287 leaf_space_used(leaf, 0, nritems), nritems);
2288 }
2289 return ret;
2290}
2291
2292/*
2293 * min slot controls the lowest index we're willing to push to the
2294 * right. We'll push up to and including min_slot, but no lower
2295 */
2296static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
2297 struct btrfs_root *root,
2298 struct btrfs_path *path,
2299 int data_size, int empty,
2300 struct extent_buffer *right,
2301 int free_space, u32 left_nritems,
2302 u32 min_slot)
2303{
2304 struct extent_buffer *left = path->nodes[0];
2305 struct extent_buffer *upper = path->nodes[1];
2306 struct btrfs_disk_key disk_key;
2307 int slot;
2308 u32 i;
2309 int push_space = 0;
2310 int push_items = 0;
2311 struct btrfs_item *item;
2312 u32 nr;
2313 u32 right_nritems;
2314 u32 data_end;
2315 u32 this_item_size;
2316
2317 if (empty)
2318 nr = 0;
2319 else
2320 nr = max_t(u32, 1, min_slot);
2321
2322 if (path->slots[0] >= left_nritems)
2323 push_space += data_size;
2324
2325 slot = path->slots[1];
2326 i = left_nritems - 1;
2327 while (i >= nr) {
2328 item = btrfs_item_nr(left, i);
2329
2330 if (!empty && push_items > 0) {
2331 if (path->slots[0] > i)
2332 break;
2333 if (path->slots[0] == i) {
2334 int space = btrfs_leaf_free_space(root, left);
2335 if (space + push_space * 2 > free_space)
2336 break;
2337 }
2338 }
2339
2340 if (path->slots[0] == i)
2341 push_space += data_size;
2342
2343 this_item_size = btrfs_item_size(left, item);
2344 if (this_item_size + sizeof(*item) + push_space > free_space)
2345 break;
2346
2347 push_items++;
2348 push_space += this_item_size + sizeof(*item);
2349 if (i == 0)
2350 break;
2351 i--;
2352 }
2353
2354 if (push_items == 0)
2355 goto out_unlock;
2356
2357 if (!empty && push_items == left_nritems)
2358 WARN_ON(1);
2359
2360 /* push left to right */
2361 right_nritems = btrfs_header_nritems(right);
2362
2363 push_space = btrfs_item_end_nr(left, left_nritems - push_items);
2364 push_space -= leaf_data_end(root, left);
2365
2366 /* make room in the right data area */
2367 data_end = leaf_data_end(root, right);
2368 memmove_extent_buffer(right,
2369 btrfs_leaf_data(right) + data_end - push_space,
2370 btrfs_leaf_data(right) + data_end,
2371 BTRFS_LEAF_DATA_SIZE(root) - data_end);
2372
2373 /* copy from the left data area */
2374 copy_extent_buffer(right, left, btrfs_leaf_data(right) +
2375 BTRFS_LEAF_DATA_SIZE(root) - push_space,
2376 btrfs_leaf_data(left) + leaf_data_end(root, left),
2377 push_space);
2378
2379 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
2380 btrfs_item_nr_offset(0),
2381 right_nritems * sizeof(struct btrfs_item));
2382
2383 /* copy the items from left to right */
2384 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
2385 btrfs_item_nr_offset(left_nritems - push_items),
2386 push_items * sizeof(struct btrfs_item));
2387
2388 /* update the item pointers */
2389 right_nritems += push_items;
2390 btrfs_set_header_nritems(right, right_nritems);
2391 push_space = BTRFS_LEAF_DATA_SIZE(root);
2392 for (i = 0; i < right_nritems; i++) {
2393 item = btrfs_item_nr(right, i);
2394 push_space -= btrfs_item_size(right, item);
2395 btrfs_set_item_offset(right, item, push_space);
2396 }
2397
2398 left_nritems -= push_items;
2399 btrfs_set_header_nritems(left, left_nritems);
2400
2401 if (left_nritems)
2402 btrfs_mark_buffer_dirty(left);
2403 else
2404 clean_tree_block(trans, root, left);
2405
2406 btrfs_mark_buffer_dirty(right);
2407
2408 btrfs_item_key(right, &disk_key, 0);
2409 btrfs_set_node_key(upper, &disk_key, slot + 1);
2410 btrfs_mark_buffer_dirty(upper);
2411
2412 /* then fixup the leaf pointer in the path */
2413 if (path->slots[0] >= left_nritems) {
2414 path->slots[0] -= left_nritems;
2415 if (btrfs_header_nritems(path->nodes[0]) == 0)
2416 clean_tree_block(trans, root, path->nodes[0]);
2417 btrfs_tree_unlock(path->nodes[0]);
2418 free_extent_buffer(path->nodes[0]);
2419 path->nodes[0] = right;
2420 path->slots[1] += 1;
2421 } else {
2422 btrfs_tree_unlock(right);
2423 free_extent_buffer(right);
2424 }
2425 return 0;
2426
2427out_unlock:
2428 btrfs_tree_unlock(right);
2429 free_extent_buffer(right);
2430 return 1;
2431}
2432
2433/*
2434 * push some data in the path leaf to the right, trying to free up at
2435 * least data_size bytes. returns zero if the push worked, nonzero otherwise
2436 *
2437 * returns 1 if the push failed because the other node didn't have enough
2438 * room, 0 if everything worked out and < 0 if there were major errors.
2439 *
2440 * this will push starting from min_slot to the end of the leaf. It won't
2441 * push any slot lower than min_slot
2442 */
2443static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
2444 *root, struct btrfs_path *path,
2445 int min_data_size, int data_size,
2446 int empty, u32 min_slot)
2447{
2448 struct extent_buffer *left = path->nodes[0];
2449 struct extent_buffer *right;
2450 struct extent_buffer *upper;
2451 int slot;
2452 int free_space;
2453 u32 left_nritems;
2454 int ret;
2455
2456 if (!path->nodes[1])
2457 return 1;
2458
2459 slot = path->slots[1];
2460 upper = path->nodes[1];
2461 if (slot >= btrfs_header_nritems(upper) - 1)
2462 return 1;
2463
2464 btrfs_assert_tree_locked(path->nodes[1]);
2465
2466 right = read_node_slot(root, upper, slot + 1);
2467 if (right == NULL)
2468 return 1;
2469
2470 btrfs_tree_lock(right);
2471 btrfs_set_lock_blocking(right);
2472
2473 free_space = btrfs_leaf_free_space(root, right);
2474 if (free_space < data_size)
2475 goto out_unlock;
2476
2477 /* cow and double check */
2478 ret = btrfs_cow_block(trans, root, right, upper,
2479 slot + 1, &right);
2480 if (ret)
2481 goto out_unlock;
2482
2483 free_space = btrfs_leaf_free_space(root, right);
2484 if (free_space < data_size)
2485 goto out_unlock;
2486
2487 left_nritems = btrfs_header_nritems(left);
2488 if (left_nritems == 0)
2489 goto out_unlock;
2490
2491 return __push_leaf_right(trans, root, path, min_data_size, empty,
2492 right, free_space, left_nritems, min_slot);
2493out_unlock:
2494 btrfs_tree_unlock(right);
2495 free_extent_buffer(right);
2496 return 1;
2497}
2498
2499/*
2500 * push some data in the path leaf to the left, trying to free up at
2501 * least data_size bytes. returns zero if the push worked, nonzero otherwise
2502 *
2503 * max_slot can put a limit on how far into the leaf we'll push items. The
2504 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
2505 * items
2506 */
2507static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
2508 struct btrfs_root *root,
2509 struct btrfs_path *path, int data_size,
2510 int empty, struct extent_buffer *left,
2511 int free_space, u32 right_nritems,
2512 u32 max_slot)
2513{
2514 struct btrfs_disk_key disk_key;
2515 struct extent_buffer *right = path->nodes[0];
2516 int i;
2517 int push_space = 0;
2518 int push_items = 0;
2519 struct btrfs_item *item;
2520 u32 old_left_nritems;
2521 u32 nr;
2522 int ret = 0;
2523 int wret;
2524 u32 this_item_size;
2525 u32 old_left_item_size;
2526
2527 if (empty)
2528 nr = min(right_nritems, max_slot);
2529 else
2530 nr = min(right_nritems - 1, max_slot);
2531
2532 for (i = 0; i < nr; i++) {
2533 item = btrfs_item_nr(right, i);
2534
2535 if (!empty && push_items > 0) {
2536 if (path->slots[0] < i)
2537 break;
2538 if (path->slots[0] == i) {
2539 int space = btrfs_leaf_free_space(root, right);
2540 if (space + push_space * 2 > free_space)
2541 break;
2542 }
2543 }
2544
2545 if (path->slots[0] == i)
2546 push_space += data_size;
2547
2548 this_item_size = btrfs_item_size(right, item);
2549 if (this_item_size + sizeof(*item) + push_space > free_space)
2550 break;
2551
2552 push_items++;
2553 push_space += this_item_size + sizeof(*item);
2554 }
2555
2556 if (push_items == 0) {
2557 ret = 1;
2558 goto out;
2559 }
2560 if (!empty && push_items == btrfs_header_nritems(right))
2561 WARN_ON(1);
2562
2563 /* push data from right to left */
2564 copy_extent_buffer(left, right,
2565 btrfs_item_nr_offset(btrfs_header_nritems(left)),
2566 btrfs_item_nr_offset(0),
2567 push_items * sizeof(struct btrfs_item));
2568
2569 push_space = BTRFS_LEAF_DATA_SIZE(root) -
2570 btrfs_item_offset_nr(right, push_items - 1);
2571
2572 copy_extent_buffer(left, right, btrfs_leaf_data(left) +
2573 leaf_data_end(root, left) - push_space,
2574 btrfs_leaf_data(right) +
2575 btrfs_item_offset_nr(right, push_items - 1),
2576 push_space);
2577 old_left_nritems = btrfs_header_nritems(left);
2578 BUG_ON(old_left_nritems <= 0);
2579
2580 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
2581 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
2582 u32 ioff;
2583
2584 item = btrfs_item_nr(left, i);
2585
2586 ioff = btrfs_item_offset(left, item);
2587 btrfs_set_item_offset(left, item,
2588 ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
2589 }
2590 btrfs_set_header_nritems(left, old_left_nritems + push_items);
2591
2592 /* fixup right node */
2593 if (push_items > right_nritems) {
2594 printk(KERN_CRIT "push items %d nr %u\n", push_items,
2595 right_nritems);
2596 WARN_ON(1);
2597 }
2598
2599 if (push_items < right_nritems) {
2600 push_space = btrfs_item_offset_nr(right, push_items - 1) -
2601 leaf_data_end(root, right);
2602 memmove_extent_buffer(right, btrfs_leaf_data(right) +
2603 BTRFS_LEAF_DATA_SIZE(root) - push_space,
2604 btrfs_leaf_data(right) +
2605 leaf_data_end(root, right), push_space);
2606
2607 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
2608 btrfs_item_nr_offset(push_items),
2609 (btrfs_header_nritems(right) - push_items) *
2610 sizeof(struct btrfs_item));
2611 }
2612 right_nritems -= push_items;
2613 btrfs_set_header_nritems(right, right_nritems);
2614 push_space = BTRFS_LEAF_DATA_SIZE(root);
2615 for (i = 0; i < right_nritems; i++) {
2616 item = btrfs_item_nr(right, i);
2617
2618 push_space = push_space - btrfs_item_size(right, item);
2619 btrfs_set_item_offset(right, item, push_space);
2620 }
2621
2622 btrfs_mark_buffer_dirty(left);
2623 if (right_nritems)
2624 btrfs_mark_buffer_dirty(right);
2625 else
2626 clean_tree_block(trans, root, right);
2627
2628 btrfs_item_key(right, &disk_key, 0);
2629 wret = fixup_low_keys(trans, root, path, &disk_key, 1);
2630 if (wret)
2631 ret = wret;
2632
2633 /* then fixup the leaf pointer in the path */
2634 if (path->slots[0] < push_items) {
2635 path->slots[0] += old_left_nritems;
2636 btrfs_tree_unlock(path->nodes[0]);
2637 free_extent_buffer(path->nodes[0]);
2638 path->nodes[0] = left;
2639 path->slots[1] -= 1;
2640 } else {
2641 btrfs_tree_unlock(left);
2642 free_extent_buffer(left);
2643 path->slots[0] -= push_items;
2644 }
2645 BUG_ON(path->slots[0] < 0);
2646 return ret;
2647out:
2648 btrfs_tree_unlock(left);
2649 free_extent_buffer(left);
2650 return ret;
2651}
2652
2653/*
2654 * push some data in the path leaf to the left, trying to free up at
2655 * least data_size bytes. returns zero if the push worked, nonzero otherwise
2656 *
2657 * max_slot can put a limit on how far into the leaf we'll push items. The
2658 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
2659 * items
2660 */
2661static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
2662 *root, struct btrfs_path *path, int min_data_size,
2663 int data_size, int empty, u32 max_slot)
2664{
2665 struct extent_buffer *right = path->nodes[0];
2666 struct extent_buffer *left;
2667 int slot;
2668 int free_space;
2669 u32 right_nritems;
2670 int ret = 0;
2671
2672 slot = path->slots[1];
2673 if (slot == 0)
2674 return 1;
2675 if (!path->nodes[1])
2676 return 1;
2677
2678 right_nritems = btrfs_header_nritems(right);
2679 if (right_nritems == 0)
2680 return 1;
2681
2682 btrfs_assert_tree_locked(path->nodes[1]);
2683
2684 left = read_node_slot(root, path->nodes[1], slot - 1);
2685 if (left == NULL)
2686 return 1;
2687
2688 btrfs_tree_lock(left);
2689 btrfs_set_lock_blocking(left);
2690
2691 free_space = btrfs_leaf_free_space(root, left);
2692 if (free_space < data_size) {
2693 ret = 1;
2694 goto out;
2695 }
2696
2697 /* cow and double check */
2698 ret = btrfs_cow_block(trans, root, left,
2699 path->nodes[1], slot - 1, &left);
2700 if (ret) {
2701 /* we hit -ENOSPC, but it isn't fatal here */
2702 ret = 1;
2703 goto out;
2704 }
2705
2706 free_space = btrfs_leaf_free_space(root, left);
2707 if (free_space < data_size) {
2708 ret = 1;
2709 goto out;
2710 }
2711
2712 return __push_leaf_left(trans, root, path, min_data_size,
2713 empty, left, free_space, right_nritems,
2714 max_slot);
2715out:
2716 btrfs_tree_unlock(left);
2717 free_extent_buffer(left);
2718 return ret;
2719}
2720
2721/*
2722 * split the path's leaf in two, making sure there is at least data_size
2723 * available for the resulting leaf level of the path.
2724 *
2725 * returns 0 if all went well and < 0 on failure.
2726 */
2727static noinline int copy_for_split(struct btrfs_trans_handle *trans,
2728 struct btrfs_root *root,
2729 struct btrfs_path *path,
2730 struct extent_buffer *l,
2731 struct extent_buffer *right,
2732 int slot, int mid, int nritems)
2733{
2734 int data_copy_size;
2735 int rt_data_off;
2736 int i;
2737 int ret = 0;
2738 int wret;
2739 struct btrfs_disk_key disk_key;
2740
2741 nritems = nritems - mid;
2742 btrfs_set_header_nritems(right, nritems);
2743 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
2744
2745 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
2746 btrfs_item_nr_offset(mid),
2747 nritems * sizeof(struct btrfs_item));
2748
2749 copy_extent_buffer(right, l,
2750 btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
2751 data_copy_size, btrfs_leaf_data(l) +
2752 leaf_data_end(root, l), data_copy_size);
2753
2754 rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
2755 btrfs_item_end_nr(l, mid);
2756
2757 for (i = 0; i < nritems; i++) {
2758 struct btrfs_item *item = btrfs_item_nr(right, i);
2759 u32 ioff;
2760
2761 ioff = btrfs_item_offset(right, item);
2762 btrfs_set_item_offset(right, item, ioff + rt_data_off);
2763 }
2764
2765 btrfs_set_header_nritems(l, mid);
2766 ret = 0;
2767 btrfs_item_key(right, &disk_key, 0);
2768 wret = insert_ptr(trans, root, path, &disk_key, right->start,
2769 path->slots[1] + 1, 1);
2770 if (wret)
2771 ret = wret;
2772
2773 btrfs_mark_buffer_dirty(right);
2774 btrfs_mark_buffer_dirty(l);
2775 BUG_ON(path->slots[0] != slot);
2776
2777 if (mid <= slot) {
2778 btrfs_tree_unlock(path->nodes[0]);
2779 free_extent_buffer(path->nodes[0]);
2780 path->nodes[0] = right;
2781 path->slots[0] -= mid;
2782 path->slots[1] += 1;
2783 } else {
2784 btrfs_tree_unlock(right);
2785 free_extent_buffer(right);
2786 }
2787
2788 BUG_ON(path->slots[0] < 0);
2789
2790 return ret;
2791}
2792
2793/*
2794 * double splits happen when we need to insert a big item in the middle
2795 * of a leaf. A double split can leave us with 3 mostly empty leaves:
2796 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
2797 * A B C
2798 *
2799 * We avoid this by trying to push the items on either side of our target
2800 * into the adjacent leaves. If all goes well we can avoid the double split
2801 * completely.
2802 */
2803static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
2804 struct btrfs_root *root,
2805 struct btrfs_path *path,
2806 int data_size)
2807{
2808 int ret;
2809 int progress = 0;
2810 int slot;
2811 u32 nritems;
2812
2813 slot = path->slots[0];
2814
2815 /*
2816 * try to push all the items after our slot into the
2817 * right leaf
2818 */
2819 ret = push_leaf_right(trans, root, path, 1, data_size, 0, slot);
2820 if (ret < 0)
2821 return ret;
2822
2823 if (ret == 0)
2824 progress++;
2825
2826 nritems = btrfs_header_nritems(path->nodes[0]);
2827 /*
2828 * our goal is to get our slot at the start or end of a leaf. If
2829 * we've done so we're done
2830 */
2831 if (path->slots[0] == 0 || path->slots[0] == nritems)
2832 return 0;
2833
2834 if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
2835 return 0;
2836
2837 /* try to push all the items before our slot into the next leaf */
2838 slot = path->slots[0];
2839 ret = push_leaf_left(trans, root, path, 1, data_size, 0, slot);
2840 if (ret < 0)
2841 return ret;
2842
2843 if (ret == 0)
2844 progress++;
2845
2846 if (progress)
2847 return 0;
2848 return 1;
2849}
2850
2851/*
2852 * split the path's leaf in two, making sure there is at least data_size
2853 * available for the resulting leaf level of the path.
2854 *
2855 * returns 0 if all went well and < 0 on failure.
2856 */
2857static noinline int split_leaf(struct btrfs_trans_handle *trans,
2858 struct btrfs_root *root,
2859 struct btrfs_key *ins_key,
2860 struct btrfs_path *path, int data_size,
2861 int extend)
2862{
2863 struct btrfs_disk_key disk_key;
2864 struct extent_buffer *l;
2865 u32 nritems;
2866 int mid;
2867 int slot;
2868 struct extent_buffer *right;
2869 int ret = 0;
2870 int wret;
2871 int split;
2872 int num_doubles = 0;
2873 int tried_avoid_double = 0;
2874
2875 l = path->nodes[0];
2876 slot = path->slots[0];
2877 if (extend && data_size + btrfs_item_size_nr(l, slot) +
2878 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root))
2879 return -EOVERFLOW;
2880
2881 /* first try to make some room by pushing left and right */
2882 if (data_size) {
2883 wret = push_leaf_right(trans, root, path, data_size,
2884 data_size, 0, 0);
2885 if (wret < 0)
2886 return wret;
2887 if (wret) {
2888 wret = push_leaf_left(trans, root, path, data_size,
2889 data_size, 0, (u32)-1);
2890 if (wret < 0)
2891 return wret;
2892 }
2893 l = path->nodes[0];
2894
2895 /* did the pushes work? */
2896 if (btrfs_leaf_free_space(root, l) >= data_size)
2897 return 0;
2898 }
2899
2900 if (!path->nodes[1]) {
2901 ret = insert_new_root(trans, root, path, 1);
2902 if (ret)
2903 return ret;
2904 }
2905again:
2906 split = 1;
2907 l = path->nodes[0];
2908 slot = path->slots[0];
2909 nritems = btrfs_header_nritems(l);
2910 mid = (nritems + 1) / 2;
2911
2912 if (mid <= slot) {
2913 if (nritems == 1 ||
2914 leaf_space_used(l, mid, nritems - mid) + data_size >
2915 BTRFS_LEAF_DATA_SIZE(root)) {
2916 if (slot >= nritems) {
2917 split = 0;
2918 } else {
2919 mid = slot;
2920 if (mid != nritems &&
2921 leaf_space_used(l, mid, nritems - mid) +
2922 data_size > BTRFS_LEAF_DATA_SIZE(root)) {
2923 if (data_size && !tried_avoid_double)
2924 goto push_for_double;
2925 split = 2;
2926 }
2927 }
2928 }
2929 } else {
2930 if (leaf_space_used(l, 0, mid) + data_size >
2931 BTRFS_LEAF_DATA_SIZE(root)) {
2932 if (!extend && data_size && slot == 0) {
2933 split = 0;
2934 } else if ((extend || !data_size) && slot == 0) {
2935 mid = 1;
2936 } else {
2937 mid = slot;
2938 if (mid != nritems &&
2939 leaf_space_used(l, mid, nritems - mid) +
2940 data_size > BTRFS_LEAF_DATA_SIZE(root)) {
2941 if (data_size && !tried_avoid_double)
2942 goto push_for_double;
2943 split = 2 ;
2944 }
2945 }
2946 }
2947 }
2948
2949 if (split == 0)
2950 btrfs_cpu_key_to_disk(&disk_key, ins_key);
2951 else
2952 btrfs_item_key(l, &disk_key, mid);
2953
2954 right = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
2955 root->root_key.objectid,
2956 &disk_key, 0, l->start, 0);
2957 if (IS_ERR(right))
2958 return PTR_ERR(right);
2959
2960 root_add_used(root, root->leafsize);
2961
2962 memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
2963 btrfs_set_header_bytenr(right, right->start);
2964 btrfs_set_header_generation(right, trans->transid);
2965 btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
2966 btrfs_set_header_owner(right, root->root_key.objectid);
2967 btrfs_set_header_level(right, 0);
2968 write_extent_buffer(right, root->fs_info->fsid,
2969 (unsigned long)btrfs_header_fsid(right),
2970 BTRFS_FSID_SIZE);
2971
2972 write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
2973 (unsigned long)btrfs_header_chunk_tree_uuid(right),
2974 BTRFS_UUID_SIZE);
2975
2976 if (split == 0) {
2977 if (mid <= slot) {
2978 btrfs_set_header_nritems(right, 0);
2979 wret = insert_ptr(trans, root, path,
2980 &disk_key, right->start,
2981 path->slots[1] + 1, 1);
2982 if (wret)
2983 ret = wret;
2984
2985 btrfs_tree_unlock(path->nodes[0]);
2986 free_extent_buffer(path->nodes[0]);
2987 path->nodes[0] = right;
2988 path->slots[0] = 0;
2989 path->slots[1] += 1;
2990 } else {
2991 btrfs_set_header_nritems(right, 0);
2992 wret = insert_ptr(trans, root, path,
2993 &disk_key,
2994 right->start,
2995 path->slots[1], 1);
2996 if (wret)
2997 ret = wret;
2998 btrfs_tree_unlock(path->nodes[0]);
2999 free_extent_buffer(path->nodes[0]);
3000 path->nodes[0] = right;
3001 path->slots[0] = 0;
3002 if (path->slots[1] == 0) {
3003 wret = fixup_low_keys(trans, root,
3004 path, &disk_key, 1);
3005 if (wret)
3006 ret = wret;
3007 }
3008 }
3009 btrfs_mark_buffer_dirty(right);
3010 return ret;
3011 }
3012
3013 ret = copy_for_split(trans, root, path, l, right, slot, mid, nritems);
3014 BUG_ON(ret);
3015
3016 if (split == 2) {
3017 BUG_ON(num_doubles != 0);
3018 num_doubles++;
3019 goto again;
3020 }
3021
3022 return ret;
3023
3024push_for_double:
3025 push_for_double_split(trans, root, path, data_size);
3026 tried_avoid_double = 1;
3027 if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
3028 return 0;
3029 goto again;
3030}
3031
3032static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3033 struct btrfs_root *root,
3034 struct btrfs_path *path, int ins_len)
3035{
3036 struct btrfs_key key;
3037 struct extent_buffer *leaf;
3038 struct btrfs_file_extent_item *fi;
3039 u64 extent_len = 0;
3040 u32 item_size;
3041 int ret;
3042
3043 leaf = path->nodes[0];
3044 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3045
3046 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3047 key.type != BTRFS_EXTENT_CSUM_KEY);
3048
3049 if (btrfs_leaf_free_space(root, leaf) >= ins_len)
3050 return 0;
3051
3052 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3053 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3054 fi = btrfs_item_ptr(leaf, path->slots[0],
3055 struct btrfs_file_extent_item);
3056 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3057 }
3058 btrfs_release_path(path);
3059
3060 path->keep_locks = 1;
3061 path->search_for_split = 1;
3062 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3063 path->search_for_split = 0;
3064 if (ret < 0)
3065 goto err;
3066
3067 ret = -EAGAIN;
3068 leaf = path->nodes[0];
3069 /* if our item isn't there or got smaller, return now */
3070 if (ret > 0 || item_size != btrfs_item_size_nr(leaf, path->slots[0]))
3071 goto err;
3072
3073 /* the leaf has changed, it now has room. return now */
3074 if (btrfs_leaf_free_space(root, path->nodes[0]) >= ins_len)
3075 goto err;
3076
3077 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3078 fi = btrfs_item_ptr(leaf, path->slots[0],
3079 struct btrfs_file_extent_item);
3080 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3081 goto err;
3082 }
3083
3084 btrfs_set_path_blocking(path);
3085 ret = split_leaf(trans, root, &key, path, ins_len, 1);
3086 if (ret)
3087 goto err;
3088
3089 path->keep_locks = 0;
3090 btrfs_unlock_up_safe(path, 1);
3091 return 0;
3092err:
3093 path->keep_locks = 0;
3094 return ret;
3095}
3096
3097static noinline int split_item(struct btrfs_trans_handle *trans,
3098 struct btrfs_root *root,
3099 struct btrfs_path *path,
3100 struct btrfs_key *new_key,
3101 unsigned long split_offset)
3102{
3103 struct extent_buffer *leaf;
3104 struct btrfs_item *item;
3105 struct btrfs_item *new_item;
3106 int slot;
3107 char *buf;
3108 u32 nritems;
3109 u32 item_size;
3110 u32 orig_offset;
3111 struct btrfs_disk_key disk_key;
3112
3113 leaf = path->nodes[0];
3114 BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
3115
3116 btrfs_set_path_blocking(path);
3117
3118 item = btrfs_item_nr(leaf, path->slots[0]);
3119 orig_offset = btrfs_item_offset(leaf, item);
3120 item_size = btrfs_item_size(leaf, item);
3121
3122 buf = kmalloc(item_size, GFP_NOFS);
3123 if (!buf)
3124 return -ENOMEM;
3125
3126 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3127 path->slots[0]), item_size);
3128
3129 slot = path->slots[0] + 1;
3130 nritems = btrfs_header_nritems(leaf);
3131 if (slot != nritems) {
3132 /* shift the items */
3133 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
3134 btrfs_item_nr_offset(slot),
3135 (nritems - slot) * sizeof(struct btrfs_item));
3136 }
3137
3138 btrfs_cpu_key_to_disk(&disk_key, new_key);
3139 btrfs_set_item_key(leaf, &disk_key, slot);
3140
3141 new_item = btrfs_item_nr(leaf, slot);
3142
3143 btrfs_set_item_offset(leaf, new_item, orig_offset);
3144 btrfs_set_item_size(leaf, new_item, item_size - split_offset);
3145
3146 btrfs_set_item_offset(leaf, item,
3147 orig_offset + item_size - split_offset);
3148 btrfs_set_item_size(leaf, item, split_offset);
3149
3150 btrfs_set_header_nritems(leaf, nritems + 1);
3151
3152 /* write the data for the start of the original item */
3153 write_extent_buffer(leaf, buf,
3154 btrfs_item_ptr_offset(leaf, path->slots[0]),
3155 split_offset);
3156
3157 /* write the data for the new item */
3158 write_extent_buffer(leaf, buf + split_offset,
3159 btrfs_item_ptr_offset(leaf, slot),
3160 item_size - split_offset);
3161 btrfs_mark_buffer_dirty(leaf);
3162
3163 BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
3164 kfree(buf);
3165 return 0;
3166}
3167
3168/*
3169 * This function splits a single item into two items,
3170 * giving 'new_key' to the new item and splitting the
3171 * old one at split_offset (from the start of the item).
3172 *
3173 * The path may be released by this operation. After
3174 * the split, the path is pointing to the old item. The
3175 * new item is going to be in the same node as the old one.
3176 *
3177 * Note, the item being split must be smaller enough to live alone on
3178 * a tree block with room for one extra struct btrfs_item
3179 *
3180 * This allows us to split the item in place, keeping a lock on the
3181 * leaf the entire time.
3182 */
3183int btrfs_split_item(struct btrfs_trans_handle *trans,
3184 struct btrfs_root *root,
3185 struct btrfs_path *path,
3186 struct btrfs_key *new_key,
3187 unsigned long split_offset)
3188{
3189 int ret;
3190 ret = setup_leaf_for_split(trans, root, path,
3191 sizeof(struct btrfs_item));
3192 if (ret)
3193 return ret;
3194
3195 ret = split_item(trans, root, path, new_key, split_offset);
3196 return ret;
3197}
3198
3199/*
3200 * This function duplicate a item, giving 'new_key' to the new item.
3201 * It guarantees both items live in the same tree leaf and the new item
3202 * is contiguous with the original item.
3203 *
3204 * This allows us to split file extent in place, keeping a lock on the
3205 * leaf the entire time.
3206 */
3207int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
3208 struct btrfs_root *root,
3209 struct btrfs_path *path,
3210 struct btrfs_key *new_key)
3211{
3212 struct extent_buffer *leaf;
3213 int ret;
3214 u32 item_size;
3215
3216 leaf = path->nodes[0];
3217 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3218 ret = setup_leaf_for_split(trans, root, path,
3219 item_size + sizeof(struct btrfs_item));
3220 if (ret)
3221 return ret;
3222
3223 path->slots[0]++;
3224 ret = setup_items_for_insert(trans, root, path, new_key, &item_size,
3225 item_size, item_size +
3226 sizeof(struct btrfs_item), 1);
3227 BUG_ON(ret);
3228
3229 leaf = path->nodes[0];
3230 memcpy_extent_buffer(leaf,
3231 btrfs_item_ptr_offset(leaf, path->slots[0]),
3232 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
3233 item_size);
3234 return 0;
3235}
3236
3237/*
3238 * make the item pointed to by the path smaller. new_size indicates
3239 * how small to make it, and from_end tells us if we just chop bytes
3240 * off the end of the item or if we shift the item to chop bytes off
3241 * the front.
3242 */
3243int btrfs_truncate_item(struct btrfs_trans_handle *trans,
3244 struct btrfs_root *root,
3245 struct btrfs_path *path,
3246 u32 new_size, int from_end)
3247{
3248 int slot;
3249 struct extent_buffer *leaf;
3250 struct btrfs_item *item;
3251 u32 nritems;
3252 unsigned int data_end;
3253 unsigned int old_data_start;
3254 unsigned int old_size;
3255 unsigned int size_diff;
3256 int i;
3257
3258 leaf = path->nodes[0];
3259 slot = path->slots[0];
3260
3261 old_size = btrfs_item_size_nr(leaf, slot);
3262 if (old_size == new_size)
3263 return 0;
3264
3265 nritems = btrfs_header_nritems(leaf);
3266 data_end = leaf_data_end(root, leaf);
3267
3268 old_data_start = btrfs_item_offset_nr(leaf, slot);
3269
3270 size_diff = old_size - new_size;
3271
3272 BUG_ON(slot < 0);
3273 BUG_ON(slot >= nritems);
3274
3275 /*
3276 * item0..itemN ... dataN.offset..dataN.size .. data0.size
3277 */
3278 /* first correct the data pointers */
3279 for (i = slot; i < nritems; i++) {
3280 u32 ioff;
3281 item = btrfs_item_nr(leaf, i);
3282
3283 ioff = btrfs_item_offset(leaf, item);
3284 btrfs_set_item_offset(leaf, item, ioff + size_diff);
3285 }
3286
3287 /* shift the data */
3288 if (from_end) {
3289 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3290 data_end + size_diff, btrfs_leaf_data(leaf) +
3291 data_end, old_data_start + new_size - data_end);
3292 } else {
3293 struct btrfs_disk_key disk_key;
3294 u64 offset;
3295
3296 btrfs_item_key(leaf, &disk_key, slot);
3297
3298 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
3299 unsigned long ptr;
3300 struct btrfs_file_extent_item *fi;
3301
3302 fi = btrfs_item_ptr(leaf, slot,
3303 struct btrfs_file_extent_item);
3304 fi = (struct btrfs_file_extent_item *)(
3305 (unsigned long)fi - size_diff);
3306
3307 if (btrfs_file_extent_type(leaf, fi) ==
3308 BTRFS_FILE_EXTENT_INLINE) {
3309 ptr = btrfs_item_ptr_offset(leaf, slot);
3310 memmove_extent_buffer(leaf, ptr,
3311 (unsigned long)fi,
3312 offsetof(struct btrfs_file_extent_item,
3313 disk_bytenr));
3314 }
3315 }
3316
3317 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3318 data_end + size_diff, btrfs_leaf_data(leaf) +
3319 data_end, old_data_start - data_end);
3320
3321 offset = btrfs_disk_key_offset(&disk_key);
3322 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
3323 btrfs_set_item_key(leaf, &disk_key, slot);
3324 if (slot == 0)
3325 fixup_low_keys(trans, root, path, &disk_key, 1);
3326 }
3327
3328 item = btrfs_item_nr(leaf, slot);
3329 btrfs_set_item_size(leaf, item, new_size);
3330 btrfs_mark_buffer_dirty(leaf);
3331
3332 if (btrfs_leaf_free_space(root, leaf) < 0) {
3333 btrfs_print_leaf(root, leaf);
3334 BUG();
3335 }
3336 return 0;
3337}
3338
3339/*
3340 * make the item pointed to by the path bigger, data_size is the new size.
3341 */
3342int btrfs_extend_item(struct btrfs_trans_handle *trans,
3343 struct btrfs_root *root, struct btrfs_path *path,
3344 u32 data_size)
3345{
3346 int slot;
3347 struct extent_buffer *leaf;
3348 struct btrfs_item *item;
3349 u32 nritems;
3350 unsigned int data_end;
3351 unsigned int old_data;
3352 unsigned int old_size;
3353 int i;
3354
3355 leaf = path->nodes[0];
3356
3357 nritems = btrfs_header_nritems(leaf);
3358 data_end = leaf_data_end(root, leaf);
3359
3360 if (btrfs_leaf_free_space(root, leaf) < data_size) {
3361 btrfs_print_leaf(root, leaf);
3362 BUG();
3363 }
3364 slot = path->slots[0];
3365 old_data = btrfs_item_end_nr(leaf, slot);
3366
3367 BUG_ON(slot < 0);
3368 if (slot >= nritems) {
3369 btrfs_print_leaf(root, leaf);
3370 printk(KERN_CRIT "slot %d too large, nritems %d\n",
3371 slot, nritems);
3372 BUG_ON(1);
3373 }
3374
3375 /*
3376 * item0..itemN ... dataN.offset..dataN.size .. data0.size
3377 */
3378 /* first correct the data pointers */
3379 for (i = slot; i < nritems; i++) {
3380 u32 ioff;
3381 item = btrfs_item_nr(leaf, i);
3382
3383 ioff = btrfs_item_offset(leaf, item);
3384 btrfs_set_item_offset(leaf, item, ioff - data_size);
3385 }
3386
3387 /* shift the data */
3388 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3389 data_end - data_size, btrfs_leaf_data(leaf) +
3390 data_end, old_data - data_end);
3391
3392 data_end = old_data;
3393 old_size = btrfs_item_size_nr(leaf, slot);
3394 item = btrfs_item_nr(leaf, slot);
3395 btrfs_set_item_size(leaf, item, old_size + data_size);
3396 btrfs_mark_buffer_dirty(leaf);
3397
3398 if (btrfs_leaf_free_space(root, leaf) < 0) {
3399 btrfs_print_leaf(root, leaf);
3400 BUG();
3401 }
3402 return 0;
3403}
3404
3405/*
3406 * Given a key and some data, insert items into the tree.
3407 * This does all the path init required, making room in the tree if needed.
3408 * Returns the number of keys that were inserted.
3409 */
3410int btrfs_insert_some_items(struct btrfs_trans_handle *trans,
3411 struct btrfs_root *root,
3412 struct btrfs_path *path,
3413 struct btrfs_key *cpu_key, u32 *data_size,
3414 int nr)
3415{
3416 struct extent_buffer *leaf;
3417 struct btrfs_item *item;
3418 int ret = 0;
3419 int slot;
3420 int i;
3421 u32 nritems;
3422 u32 total_data = 0;
3423 u32 total_size = 0;
3424 unsigned int data_end;
3425 struct btrfs_disk_key disk_key;
3426 struct btrfs_key found_key;
3427
3428 for (i = 0; i < nr; i++) {
3429 if (total_size + data_size[i] + sizeof(struct btrfs_item) >
3430 BTRFS_LEAF_DATA_SIZE(root)) {
3431 break;
3432 nr = i;
3433 }
3434 total_data += data_size[i];
3435 total_size += data_size[i] + sizeof(struct btrfs_item);
3436 }
3437 BUG_ON(nr == 0);
3438
3439 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
3440 if (ret == 0)
3441 return -EEXIST;
3442 if (ret < 0)
3443 goto out;
3444
3445 leaf = path->nodes[0];
3446
3447 nritems = btrfs_header_nritems(leaf);
3448 data_end = leaf_data_end(root, leaf);
3449
3450 if (btrfs_leaf_free_space(root, leaf) < total_size) {
3451 for (i = nr; i >= 0; i--) {
3452 total_data -= data_size[i];
3453 total_size -= data_size[i] + sizeof(struct btrfs_item);
3454 if (total_size < btrfs_leaf_free_space(root, leaf))
3455 break;
3456 }
3457 nr = i;
3458 }
3459
3460 slot = path->slots[0];
3461 BUG_ON(slot < 0);
3462
3463 if (slot != nritems) {
3464 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
3465
3466 item = btrfs_item_nr(leaf, slot);
3467 btrfs_item_key_to_cpu(leaf, &found_key, slot);
3468
3469 /* figure out how many keys we can insert in here */
3470 total_data = data_size[0];
3471 for (i = 1; i < nr; i++) {
3472 if (btrfs_comp_cpu_keys(&found_key, cpu_key + i) <= 0)
3473 break;
3474 total_data += data_size[i];
3475 }
3476 nr = i;
3477
3478 if (old_data < data_end) {
3479 btrfs_print_leaf(root, leaf);
3480 printk(KERN_CRIT "slot %d old_data %d data_end %d\n",
3481 slot, old_data, data_end);
3482 BUG_ON(1);
3483 }
3484 /*
3485 * item0..itemN ... dataN.offset..dataN.size .. data0.size
3486 */
3487 /* first correct the data pointers */
3488 for (i = slot; i < nritems; i++) {
3489 u32 ioff;
3490
3491 item = btrfs_item_nr(leaf, i);
3492 ioff = btrfs_item_offset(leaf, item);
3493 btrfs_set_item_offset(leaf, item, ioff - total_data);
3494 }
3495 /* shift the items */
3496 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
3497 btrfs_item_nr_offset(slot),
3498 (nritems - slot) * sizeof(struct btrfs_item));
3499
3500 /* shift the data */
3501 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3502 data_end - total_data, btrfs_leaf_data(leaf) +
3503 data_end, old_data - data_end);
3504 data_end = old_data;
3505 } else {
3506 /*
3507 * this sucks but it has to be done, if we are inserting at
3508 * the end of the leaf only insert 1 of the items, since we
3509 * have no way of knowing whats on the next leaf and we'd have
3510 * to drop our current locks to figure it out
3511 */
3512 nr = 1;
3513 }
3514
3515 /* setup the item for the new data */
3516 for (i = 0; i < nr; i++) {
3517 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
3518 btrfs_set_item_key(leaf, &disk_key, slot + i);
3519 item = btrfs_item_nr(leaf, slot + i);
3520 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
3521 data_end -= data_size[i];
3522 btrfs_set_item_size(leaf, item, data_size[i]);
3523 }
3524 btrfs_set_header_nritems(leaf, nritems + nr);
3525 btrfs_mark_buffer_dirty(leaf);
3526
3527 ret = 0;
3528 if (slot == 0) {
3529 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
3530 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
3531 }
3532
3533 if (btrfs_leaf_free_space(root, leaf) < 0) {
3534 btrfs_print_leaf(root, leaf);
3535 BUG();
3536 }
3537out:
3538 if (!ret)
3539 ret = nr;
3540 return ret;
3541}
3542
3543/*
3544 * this is a helper for btrfs_insert_empty_items, the main goal here is
3545 * to save stack depth by doing the bulk of the work in a function
3546 * that doesn't call btrfs_search_slot
3547 */
3548int setup_items_for_insert(struct btrfs_trans_handle *trans,
3549 struct btrfs_root *root, struct btrfs_path *path,
3550 struct btrfs_key *cpu_key, u32 *data_size,
3551 u32 total_data, u32 total_size, int nr)
3552{
3553 struct btrfs_item *item;
3554 int i;
3555 u32 nritems;
3556 unsigned int data_end;
3557 struct btrfs_disk_key disk_key;
3558 int ret;
3559 struct extent_buffer *leaf;
3560 int slot;
3561
3562 leaf = path->nodes[0];
3563 slot = path->slots[0];
3564
3565 nritems = btrfs_header_nritems(leaf);
3566 data_end = leaf_data_end(root, leaf);
3567
3568 if (btrfs_leaf_free_space(root, leaf) < total_size) {
3569 btrfs_print_leaf(root, leaf);
3570 printk(KERN_CRIT "not enough freespace need %u have %d\n",
3571 total_size, btrfs_leaf_free_space(root, leaf));
3572 BUG();
3573 }
3574
3575 if (slot != nritems) {
3576 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
3577
3578 if (old_data < data_end) {
3579 btrfs_print_leaf(root, leaf);
3580 printk(KERN_CRIT "slot %d old_data %d data_end %d\n",
3581 slot, old_data, data_end);
3582 BUG_ON(1);
3583 }
3584 /*
3585 * item0..itemN ... dataN.offset..dataN.size .. data0.size
3586 */
3587 /* first correct the data pointers */
3588 for (i = slot; i < nritems; i++) {
3589 u32 ioff;
3590
3591 item = btrfs_item_nr(leaf, i);
3592 ioff = btrfs_item_offset(leaf, item);
3593 btrfs_set_item_offset(leaf, item, ioff - total_data);
3594 }
3595 /* shift the items */
3596 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
3597 btrfs_item_nr_offset(slot),
3598 (nritems - slot) * sizeof(struct btrfs_item));
3599
3600 /* shift the data */
3601 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3602 data_end - total_data, btrfs_leaf_data(leaf) +
3603 data_end, old_data - data_end);
3604 data_end = old_data;
3605 }
3606
3607 /* setup the item for the new data */
3608 for (i = 0; i < nr; i++) {
3609 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
3610 btrfs_set_item_key(leaf, &disk_key, slot + i);
3611 item = btrfs_item_nr(leaf, slot + i);
3612 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
3613 data_end -= data_size[i];
3614 btrfs_set_item_size(leaf, item, data_size[i]);
3615 }
3616
3617 btrfs_set_header_nritems(leaf, nritems + nr);
3618
3619 ret = 0;
3620 if (slot == 0) {
3621 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
3622 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
3623 }
3624 btrfs_unlock_up_safe(path, 1);
3625 btrfs_mark_buffer_dirty(leaf);
3626
3627 if (btrfs_leaf_free_space(root, leaf) < 0) {
3628 btrfs_print_leaf(root, leaf);
3629 BUG();
3630 }
3631 return ret;
3632}
3633
3634/*
3635 * Given a key and some data, insert items into the tree.
3636 * This does all the path init required, making room in the tree if needed.
3637 */
3638int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
3639 struct btrfs_root *root,
3640 struct btrfs_path *path,
3641 struct btrfs_key *cpu_key, u32 *data_size,
3642 int nr)
3643{
3644 int ret = 0;
3645 int slot;
3646 int i;
3647 u32 total_size = 0;
3648 u32 total_data = 0;
3649
3650 for (i = 0; i < nr; i++)
3651 total_data += data_size[i];
3652
3653 total_size = total_data + (nr * sizeof(struct btrfs_item));
3654 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
3655 if (ret == 0)
3656 return -EEXIST;
3657 if (ret < 0)
3658 goto out;
3659
3660 slot = path->slots[0];
3661 BUG_ON(slot < 0);
3662
3663 ret = setup_items_for_insert(trans, root, path, cpu_key, data_size,
3664 total_data, total_size, nr);
3665
3666out:
3667 return ret;
3668}
3669
3670/*
3671 * Given a key and some data, insert an item into the tree.
3672 * This does all the path init required, making room in the tree if needed.
3673 */
3674int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
3675 *root, struct btrfs_key *cpu_key, void *data, u32
3676 data_size)
3677{
3678 int ret = 0;
3679 struct btrfs_path *path;
3680 struct extent_buffer *leaf;
3681 unsigned long ptr;
3682
3683 path = btrfs_alloc_path();
3684 if (!path)
3685 return -ENOMEM;
3686 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
3687 if (!ret) {
3688 leaf = path->nodes[0];
3689 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
3690 write_extent_buffer(leaf, data, ptr, data_size);
3691 btrfs_mark_buffer_dirty(leaf);
3692 }
3693 btrfs_free_path(path);
3694 return ret;
3695}
3696
3697/*
3698 * delete the pointer from a given node.
3699 *
3700 * the tree should have been previously balanced so the deletion does not
3701 * empty a node.
3702 */
3703static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3704 struct btrfs_path *path, int level, int slot)
3705{
3706 struct extent_buffer *parent = path->nodes[level];
3707 u32 nritems;
3708 int ret = 0;
3709 int wret;
3710
3711 nritems = btrfs_header_nritems(parent);
3712 if (slot != nritems - 1) {
3713 memmove_extent_buffer(parent,
3714 btrfs_node_key_ptr_offset(slot),
3715 btrfs_node_key_ptr_offset(slot + 1),
3716 sizeof(struct btrfs_key_ptr) *
3717 (nritems - slot - 1));
3718 }
3719 nritems--;
3720 btrfs_set_header_nritems(parent, nritems);
3721 if (nritems == 0 && parent == root->node) {
3722 BUG_ON(btrfs_header_level(root->node) != 1);
3723 /* just turn the root into a leaf and break */
3724 btrfs_set_header_level(root->node, 0);
3725 } else if (slot == 0) {
3726 struct btrfs_disk_key disk_key;
3727
3728 btrfs_node_key(parent, &disk_key, 0);
3729 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
3730 if (wret)
3731 ret = wret;
3732 }
3733 btrfs_mark_buffer_dirty(parent);
3734 return ret;
3735}
3736
3737/*
3738 * a helper function to delete the leaf pointed to by path->slots[1] and
3739 * path->nodes[1].
3740 *
3741 * This deletes the pointer in path->nodes[1] and frees the leaf
3742 * block extent. zero is returned if it all worked out, < 0 otherwise.
3743 *
3744 * The path must have already been setup for deleting the leaf, including
3745 * all the proper balancing. path->nodes[1] must be locked.
3746 */
3747static noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans,
3748 struct btrfs_root *root,
3749 struct btrfs_path *path,
3750 struct extent_buffer *leaf)
3751{
3752 int ret;
3753
3754 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
3755 ret = del_ptr(trans, root, path, 1, path->slots[1]);
3756 if (ret)
3757 return ret;
3758
3759 /*
3760 * btrfs_free_extent is expensive, we want to make sure we
3761 * aren't holding any locks when we call it
3762 */
3763 btrfs_unlock_up_safe(path, 0);
3764
3765 root_sub_used(root, leaf->len);
3766
3767 btrfs_free_tree_block(trans, root, leaf, 0, 1);
3768 return 0;
3769}
3770/*
3771 * delete the item at the leaf level in path. If that empties
3772 * the leaf, remove it from the tree
3773 */
3774int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3775 struct btrfs_path *path, int slot, int nr)
3776{
3777 struct extent_buffer *leaf;
3778 struct btrfs_item *item;
3779 int last_off;
3780 int dsize = 0;
3781 int ret = 0;
3782 int wret;
3783 int i;
3784 u32 nritems;
3785
3786 leaf = path->nodes[0];
3787 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
3788
3789 for (i = 0; i < nr; i++)
3790 dsize += btrfs_item_size_nr(leaf, slot + i);
3791
3792 nritems = btrfs_header_nritems(leaf);
3793
3794 if (slot + nr != nritems) {
3795 int data_end = leaf_data_end(root, leaf);
3796
3797 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
3798 data_end + dsize,
3799 btrfs_leaf_data(leaf) + data_end,
3800 last_off - data_end);
3801
3802 for (i = slot + nr; i < nritems; i++) {
3803 u32 ioff;
3804
3805 item = btrfs_item_nr(leaf, i);
3806 ioff = btrfs_item_offset(leaf, item);
3807 btrfs_set_item_offset(leaf, item, ioff + dsize);
3808 }
3809
3810 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
3811 btrfs_item_nr_offset(slot + nr),
3812 sizeof(struct btrfs_item) *
3813 (nritems - slot - nr));
3814 }
3815 btrfs_set_header_nritems(leaf, nritems - nr);
3816 nritems -= nr;
3817
3818 /* delete the leaf if we've emptied it */
3819 if (nritems == 0) {
3820 if (leaf == root->node) {
3821 btrfs_set_header_level(leaf, 0);
3822 } else {
3823 btrfs_set_path_blocking(path);
3824 clean_tree_block(trans, root, leaf);
3825 ret = btrfs_del_leaf(trans, root, path, leaf);
3826 BUG_ON(ret);
3827 }
3828 } else {
3829 int used = leaf_space_used(leaf, 0, nritems);
3830 if (slot == 0) {
3831 struct btrfs_disk_key disk_key;
3832
3833 btrfs_item_key(leaf, &disk_key, 0);
3834 wret = fixup_low_keys(trans, root, path,
3835 &disk_key, 1);
3836 if (wret)
3837 ret = wret;
3838 }
3839
3840 /* delete the leaf if it is mostly empty */
3841 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
3842 /* push_leaf_left fixes the path.
3843 * make sure the path still points to our leaf
3844 * for possible call to del_ptr below
3845 */
3846 slot = path->slots[1];
3847 extent_buffer_get(leaf);
3848
3849 btrfs_set_path_blocking(path);
3850 wret = push_leaf_left(trans, root, path, 1, 1,
3851 1, (u32)-1);
3852 if (wret < 0 && wret != -ENOSPC)
3853 ret = wret;
3854
3855 if (path->nodes[0] == leaf &&
3856 btrfs_header_nritems(leaf)) {
3857 wret = push_leaf_right(trans, root, path, 1,
3858 1, 1, 0);
3859 if (wret < 0 && wret != -ENOSPC)
3860 ret = wret;
3861 }
3862
3863 if (btrfs_header_nritems(leaf) == 0) {
3864 path->slots[1] = slot;
3865 ret = btrfs_del_leaf(trans, root, path, leaf);
3866 BUG_ON(ret);
3867 free_extent_buffer(leaf);
3868 } else {
3869 /* if we're still in the path, make sure
3870 * we're dirty. Otherwise, one of the
3871 * push_leaf functions must have already
3872 * dirtied this buffer
3873 */
3874 if (path->nodes[0] == leaf)
3875 btrfs_mark_buffer_dirty(leaf);
3876 free_extent_buffer(leaf);
3877 }
3878 } else {
3879 btrfs_mark_buffer_dirty(leaf);
3880 }
3881 }
3882 return ret;
3883}
3884
3885/*
3886 * search the tree again to find a leaf with lesser keys
3887 * returns 0 if it found something or 1 if there are no lesser leaves.
3888 * returns < 0 on io errors.
3889 *
3890 * This may release the path, and so you may lose any locks held at the
3891 * time you call it.
3892 */
3893int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
3894{
3895 struct btrfs_key key;
3896 struct btrfs_disk_key found_key;
3897 int ret;
3898
3899 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
3900
3901 if (key.offset > 0)
3902 key.offset--;
3903 else if (key.type > 0)
3904 key.type--;
3905 else if (key.objectid > 0)
3906 key.objectid--;
3907 else
3908 return 1;
3909
3910 btrfs_release_path(path);
3911 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3912 if (ret < 0)
3913 return ret;
3914 btrfs_item_key(path->nodes[0], &found_key, 0);
3915 ret = comp_keys(&found_key, &key);
3916 if (ret < 0)
3917 return 0;
3918 return 1;
3919}
3920
3921/*
3922 * A helper function to walk down the tree starting at min_key, and looking
3923 * for nodes or leaves that are either in cache or have a minimum
3924 * transaction id. This is used by the btree defrag code, and tree logging
3925 *
3926 * This does not cow, but it does stuff the starting key it finds back
3927 * into min_key, so you can call btrfs_search_slot with cow=1 on the
3928 * key and get a writable path.
3929 *
3930 * This does lock as it descends, and path->keep_locks should be set
3931 * to 1 by the caller.
3932 *
3933 * This honors path->lowest_level to prevent descent past a given level
3934 * of the tree.
3935 *
3936 * min_trans indicates the oldest transaction that you are interested
3937 * in walking through. Any nodes or leaves older than min_trans are
3938 * skipped over (without reading them).
3939 *
3940 * returns zero if something useful was found, < 0 on error and 1 if there
3941 * was nothing in the tree that matched the search criteria.
3942 */
3943int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
3944 struct btrfs_key *max_key,
3945 struct btrfs_path *path, int cache_only,
3946 u64 min_trans)
3947{
3948 struct extent_buffer *cur;
3949 struct btrfs_key found_key;
3950 int slot;
3951 int sret;
3952 u32 nritems;
3953 int level;
3954 int ret = 1;
3955
3956 WARN_ON(!path->keep_locks);
3957again:
3958 cur = btrfs_read_lock_root_node(root);
3959 level = btrfs_header_level(cur);
3960 WARN_ON(path->nodes[level]);
3961 path->nodes[level] = cur;
3962 path->locks[level] = BTRFS_READ_LOCK;
3963
3964 if (btrfs_header_generation(cur) < min_trans) {
3965 ret = 1;
3966 goto out;
3967 }
3968 while (1) {
3969 nritems = btrfs_header_nritems(cur);
3970 level = btrfs_header_level(cur);
3971 sret = bin_search(cur, min_key, level, &slot);
3972
3973 /* at the lowest level, we're done, setup the path and exit */
3974 if (level == path->lowest_level) {
3975 if (slot >= nritems)
3976 goto find_next_key;
3977 ret = 0;
3978 path->slots[level] = slot;
3979 btrfs_item_key_to_cpu(cur, &found_key, slot);
3980 goto out;
3981 }
3982 if (sret && slot > 0)
3983 slot--;
3984 /*
3985 * check this node pointer against the cache_only and
3986 * min_trans parameters. If it isn't in cache or is too
3987 * old, skip to the next one.
3988 */
3989 while (slot < nritems) {
3990 u64 blockptr;
3991 u64 gen;
3992 struct extent_buffer *tmp;
3993 struct btrfs_disk_key disk_key;
3994
3995 blockptr = btrfs_node_blockptr(cur, slot);
3996 gen = btrfs_node_ptr_generation(cur, slot);
3997 if (gen < min_trans) {
3998 slot++;
3999 continue;
4000 }
4001 if (!cache_only)
4002 break;
4003
4004 if (max_key) {
4005 btrfs_node_key(cur, &disk_key, slot);
4006 if (comp_keys(&disk_key, max_key) >= 0) {
4007 ret = 1;
4008 goto out;
4009 }
4010 }
4011
4012 tmp = btrfs_find_tree_block(root, blockptr,
4013 btrfs_level_size(root, level - 1));
4014
4015 if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
4016 free_extent_buffer(tmp);
4017 break;
4018 }
4019 if (tmp)
4020 free_extent_buffer(tmp);
4021 slot++;
4022 }
4023find_next_key:
4024 /*
4025 * we didn't find a candidate key in this node, walk forward
4026 * and find another one
4027 */
4028 if (slot >= nritems) {
4029 path->slots[level] = slot;
4030 btrfs_set_path_blocking(path);
4031 sret = btrfs_find_next_key(root, path, min_key, level,
4032 cache_only, min_trans);
4033 if (sret == 0) {
4034 btrfs_release_path(path);
4035 goto again;
4036 } else {
4037 goto out;
4038 }
4039 }
4040 /* save our key for returning back */
4041 btrfs_node_key_to_cpu(cur, &found_key, slot);
4042 path->slots[level] = slot;
4043 if (level == path->lowest_level) {
4044 ret = 0;
4045 unlock_up(path, level, 1);
4046 goto out;
4047 }
4048 btrfs_set_path_blocking(path);
4049 cur = read_node_slot(root, cur, slot);
4050 BUG_ON(!cur);
4051
4052 btrfs_tree_read_lock(cur);
4053
4054 path->locks[level - 1] = BTRFS_READ_LOCK;
4055 path->nodes[level - 1] = cur;
4056 unlock_up(path, level, 1);
4057 btrfs_clear_path_blocking(path, NULL, 0);
4058 }
4059out:
4060 if (ret == 0)
4061 memcpy(min_key, &found_key, sizeof(found_key));
4062 btrfs_set_path_blocking(path);
4063 return ret;
4064}
4065
4066/*
4067 * this is similar to btrfs_next_leaf, but does not try to preserve
4068 * and fixup the path. It looks for and returns the next key in the
4069 * tree based on the current path and the cache_only and min_trans
4070 * parameters.
4071 *
4072 * 0 is returned if another key is found, < 0 if there are any errors
4073 * and 1 is returned if there are no higher keys in the tree
4074 *
4075 * path->keep_locks should be set to 1 on the search made before
4076 * calling this function.
4077 */
4078int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4079 struct btrfs_key *key, int level,
4080 int cache_only, u64 min_trans)
4081{
4082 int slot;
4083 struct extent_buffer *c;
4084
4085 WARN_ON(!path->keep_locks);
4086 while (level < BTRFS_MAX_LEVEL) {
4087 if (!path->nodes[level])
4088 return 1;
4089
4090 slot = path->slots[level] + 1;
4091 c = path->nodes[level];
4092next:
4093 if (slot >= btrfs_header_nritems(c)) {
4094 int ret;
4095 int orig_lowest;
4096 struct btrfs_key cur_key;
4097 if (level + 1 >= BTRFS_MAX_LEVEL ||
4098 !path->nodes[level + 1])
4099 return 1;
4100
4101 if (path->locks[level + 1]) {
4102 level++;
4103 continue;
4104 }
4105
4106 slot = btrfs_header_nritems(c) - 1;
4107 if (level == 0)
4108 btrfs_item_key_to_cpu(c, &cur_key, slot);
4109 else
4110 btrfs_node_key_to_cpu(c, &cur_key, slot);
4111
4112 orig_lowest = path->lowest_level;
4113 btrfs_release_path(path);
4114 path->lowest_level = level;
4115 ret = btrfs_search_slot(NULL, root, &cur_key, path,
4116 0, 0);
4117 path->lowest_level = orig_lowest;
4118 if (ret < 0)
4119 return ret;
4120
4121 c = path->nodes[level];
4122 slot = path->slots[level];
4123 if (ret == 0)
4124 slot++;
4125 goto next;
4126 }
4127
4128 if (level == 0)
4129 btrfs_item_key_to_cpu(c, key, slot);
4130 else {
4131 u64 blockptr = btrfs_node_blockptr(c, slot);
4132 u64 gen = btrfs_node_ptr_generation(c, slot);
4133
4134 if (cache_only) {
4135 struct extent_buffer *cur;
4136 cur = btrfs_find_tree_block(root, blockptr,
4137 btrfs_level_size(root, level - 1));
4138 if (!cur || !btrfs_buffer_uptodate(cur, gen)) {
4139 slot++;
4140 if (cur)
4141 free_extent_buffer(cur);
4142 goto next;
4143 }
4144 free_extent_buffer(cur);
4145 }
4146 if (gen < min_trans) {
4147 slot++;
4148 goto next;
4149 }
4150 btrfs_node_key_to_cpu(c, key, slot);
4151 }
4152 return 0;
4153 }
4154 return 1;
4155}
4156
4157/*
4158 * search the tree again to find a leaf with greater keys
4159 * returns 0 if it found something or 1 if there are no greater leaves.
4160 * returns < 0 on io errors.
4161 */
4162int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
4163{
4164 int slot;
4165 int level;
4166 struct extent_buffer *c;
4167 struct extent_buffer *next;
4168 struct btrfs_key key;
4169 u32 nritems;
4170 int ret;
4171 int old_spinning = path->leave_spinning;
4172 int next_rw_lock = 0;
4173
4174 nritems = btrfs_header_nritems(path->nodes[0]);
4175 if (nritems == 0)
4176 return 1;
4177
4178 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
4179again:
4180 level = 1;
4181 next = NULL;
4182 next_rw_lock = 0;
4183 btrfs_release_path(path);
4184
4185 path->keep_locks = 1;
4186 path->leave_spinning = 1;
4187
4188 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4189 path->keep_locks = 0;
4190
4191 if (ret < 0)
4192 return ret;
4193
4194 nritems = btrfs_header_nritems(path->nodes[0]);
4195 /*
4196 * by releasing the path above we dropped all our locks. A balance
4197 * could have added more items next to the key that used to be
4198 * at the very end of the block. So, check again here and
4199 * advance the path if there are now more items available.
4200 */
4201 if (nritems > 0 && path->slots[0] < nritems - 1) {
4202 if (ret == 0)
4203 path->slots[0]++;
4204 ret = 0;
4205 goto done;
4206 }
4207
4208 while (level < BTRFS_MAX_LEVEL) {
4209 if (!path->nodes[level]) {
4210 ret = 1;
4211 goto done;
4212 }
4213
4214 slot = path->slots[level] + 1;
4215 c = path->nodes[level];
4216 if (slot >= btrfs_header_nritems(c)) {
4217 level++;
4218 if (level == BTRFS_MAX_LEVEL) {
4219 ret = 1;
4220 goto done;
4221 }
4222 continue;
4223 }
4224
4225 if (next) {
4226 btrfs_tree_unlock_rw(next, next_rw_lock);
4227 free_extent_buffer(next);
4228 }
4229
4230 next = c;
4231 next_rw_lock = path->locks[level];
4232 ret = read_block_for_search(NULL, root, path, &next, level,
4233 slot, &key);
4234 if (ret == -EAGAIN)
4235 goto again;
4236
4237 if (ret < 0) {
4238 btrfs_release_path(path);
4239 goto done;
4240 }
4241
4242 if (!path->skip_locking) {
4243 ret = btrfs_try_tree_read_lock(next);
4244 if (!ret) {
4245 btrfs_set_path_blocking(path);
4246 btrfs_tree_read_lock(next);
4247 btrfs_clear_path_blocking(path, next,
4248 BTRFS_READ_LOCK);
4249 }
4250 next_rw_lock = BTRFS_READ_LOCK;
4251 }
4252 break;
4253 }
4254 path->slots[level] = slot;
4255 while (1) {
4256 level--;
4257 c = path->nodes[level];
4258 if (path->locks[level])
4259 btrfs_tree_unlock_rw(c, path->locks[level]);
4260
4261 free_extent_buffer(c);
4262 path->nodes[level] = next;
4263 path->slots[level] = 0;
4264 if (!path->skip_locking)
4265 path->locks[level] = next_rw_lock;
4266 if (!level)
4267 break;
4268
4269 ret = read_block_for_search(NULL, root, path, &next, level,
4270 0, &key);
4271 if (ret == -EAGAIN)
4272 goto again;
4273
4274 if (ret < 0) {
4275 btrfs_release_path(path);
4276 goto done;
4277 }
4278
4279 if (!path->skip_locking) {
4280 ret = btrfs_try_tree_read_lock(next);
4281 if (!ret) {
4282 btrfs_set_path_blocking(path);
4283 btrfs_tree_read_lock(next);
4284 btrfs_clear_path_blocking(path, next,
4285 BTRFS_READ_LOCK);
4286 }
4287 next_rw_lock = BTRFS_READ_LOCK;
4288 }
4289 }
4290 ret = 0;
4291done:
4292 unlock_up(path, 0, 1);
4293 path->leave_spinning = old_spinning;
4294 if (!old_spinning)
4295 btrfs_set_path_blocking(path);
4296
4297 return ret;
4298}
4299
4300/*
4301 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
4302 * searching until it gets past min_objectid or finds an item of 'type'
4303 *
4304 * returns 0 if something is found, 1 if nothing was found and < 0 on error
4305 */
4306int btrfs_previous_item(struct btrfs_root *root,
4307 struct btrfs_path *path, u64 min_objectid,
4308 int type)
4309{
4310 struct btrfs_key found_key;
4311 struct extent_buffer *leaf;
4312 u32 nritems;
4313 int ret;
4314
4315 while (1) {
4316 if (path->slots[0] == 0) {
4317 btrfs_set_path_blocking(path);
4318 ret = btrfs_prev_leaf(root, path);
4319 if (ret != 0)
4320 return ret;
4321 } else {
4322 path->slots[0]--;
4323 }
4324 leaf = path->nodes[0];
4325 nritems = btrfs_header_nritems(leaf);
4326 if (nritems == 0)
4327 return 1;
4328 if (path->slots[0] == nritems)
4329 path->slots[0]--;
4330
4331 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
4332 if (found_key.objectid < min_objectid)
4333 break;
4334 if (found_key.type == type)
4335 return 0;
4336 if (found_key.objectid == min_objectid &&
4337 found_key.type < type)
4338 break;
4339 }
4340 return 1;
4341}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007,2008 Oracle. All rights reserved.
4 */
5
6#include <linux/sched.h>
7#include <linux/slab.h>
8#include <linux/rbtree.h>
9#include <linux/mm.h>
10#include "ctree.h"
11#include "disk-io.h"
12#include "transaction.h"
13#include "print-tree.h"
14#include "locking.h"
15#include "volumes.h"
16#include "qgroup.h"
17
18static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
19 *root, struct btrfs_path *path, int level);
20static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
21 const struct btrfs_key *ins_key, struct btrfs_path *path,
22 int data_size, int extend);
23static int push_node_left(struct btrfs_trans_handle *trans,
24 struct extent_buffer *dst,
25 struct extent_buffer *src, int empty);
26static int balance_node_right(struct btrfs_trans_handle *trans,
27 struct extent_buffer *dst_buf,
28 struct extent_buffer *src_buf);
29static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
30 int level, int slot);
31
32static const struct btrfs_csums {
33 u16 size;
34 const char name[10];
35 const char driver[12];
36} btrfs_csums[] = {
37 [BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
38 [BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
39 [BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
40 [BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
41 .driver = "blake2b-256" },
42};
43
44int btrfs_super_csum_size(const struct btrfs_super_block *s)
45{
46 u16 t = btrfs_super_csum_type(s);
47 /*
48 * csum type is validated at mount time
49 */
50 return btrfs_csums[t].size;
51}
52
53const char *btrfs_super_csum_name(u16 csum_type)
54{
55 /* csum type is validated at mount time */
56 return btrfs_csums[csum_type].name;
57}
58
59/*
60 * Return driver name if defined, otherwise the name that's also a valid driver
61 * name
62 */
63const char *btrfs_super_csum_driver(u16 csum_type)
64{
65 /* csum type is validated at mount time */
66 return btrfs_csums[csum_type].driver[0] ?
67 btrfs_csums[csum_type].driver :
68 btrfs_csums[csum_type].name;
69}
70
71size_t __attribute_const__ btrfs_get_num_csums(void)
72{
73 return ARRAY_SIZE(btrfs_csums);
74}
75
76struct btrfs_path *btrfs_alloc_path(void)
77{
78 return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
79}
80
81/* this also releases the path */
82void btrfs_free_path(struct btrfs_path *p)
83{
84 if (!p)
85 return;
86 btrfs_release_path(p);
87 kmem_cache_free(btrfs_path_cachep, p);
88}
89
90/*
91 * path release drops references on the extent buffers in the path
92 * and it drops any locks held by this path
93 *
94 * It is safe to call this on paths that no locks or extent buffers held.
95 */
96noinline void btrfs_release_path(struct btrfs_path *p)
97{
98 int i;
99
100 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
101 p->slots[i] = 0;
102 if (!p->nodes[i])
103 continue;
104 if (p->locks[i]) {
105 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
106 p->locks[i] = 0;
107 }
108 free_extent_buffer(p->nodes[i]);
109 p->nodes[i] = NULL;
110 }
111}
112
113/*
114 * safely gets a reference on the root node of a tree. A lock
115 * is not taken, so a concurrent writer may put a different node
116 * at the root of the tree. See btrfs_lock_root_node for the
117 * looping required.
118 *
119 * The extent buffer returned by this has a reference taken, so
120 * it won't disappear. It may stop being the root of the tree
121 * at any time because there are no locks held.
122 */
123struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
124{
125 struct extent_buffer *eb;
126
127 while (1) {
128 rcu_read_lock();
129 eb = rcu_dereference(root->node);
130
131 /*
132 * RCU really hurts here, we could free up the root node because
133 * it was COWed but we may not get the new root node yet so do
134 * the inc_not_zero dance and if it doesn't work then
135 * synchronize_rcu and try again.
136 */
137 if (atomic_inc_not_zero(&eb->refs)) {
138 rcu_read_unlock();
139 break;
140 }
141 rcu_read_unlock();
142 synchronize_rcu();
143 }
144 return eb;
145}
146
147/*
148 * Cowonly root (not-shareable trees, everything not subvolume or reloc roots),
149 * just get put onto a simple dirty list. Transaction walks this list to make
150 * sure they get properly updated on disk.
151 */
152static void add_root_to_dirty_list(struct btrfs_root *root)
153{
154 struct btrfs_fs_info *fs_info = root->fs_info;
155
156 if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
157 !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
158 return;
159
160 spin_lock(&fs_info->trans_lock);
161 if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
162 /* Want the extent tree to be the last on the list */
163 if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID)
164 list_move_tail(&root->dirty_list,
165 &fs_info->dirty_cowonly_roots);
166 else
167 list_move(&root->dirty_list,
168 &fs_info->dirty_cowonly_roots);
169 }
170 spin_unlock(&fs_info->trans_lock);
171}
172
173/*
174 * used by snapshot creation to make a copy of a root for a tree with
175 * a given objectid. The buffer with the new root node is returned in
176 * cow_ret, and this func returns zero on success or a negative error code.
177 */
178int btrfs_copy_root(struct btrfs_trans_handle *trans,
179 struct btrfs_root *root,
180 struct extent_buffer *buf,
181 struct extent_buffer **cow_ret, u64 new_root_objectid)
182{
183 struct btrfs_fs_info *fs_info = root->fs_info;
184 struct extent_buffer *cow;
185 int ret = 0;
186 int level;
187 struct btrfs_disk_key disk_key;
188
189 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
190 trans->transid != fs_info->running_transaction->transid);
191 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
192 trans->transid != root->last_trans);
193
194 level = btrfs_header_level(buf);
195 if (level == 0)
196 btrfs_item_key(buf, &disk_key, 0);
197 else
198 btrfs_node_key(buf, &disk_key, 0);
199
200 cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
201 &disk_key, level, buf->start, 0);
202 if (IS_ERR(cow))
203 return PTR_ERR(cow);
204
205 copy_extent_buffer_full(cow, buf);
206 btrfs_set_header_bytenr(cow, cow->start);
207 btrfs_set_header_generation(cow, trans->transid);
208 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
209 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
210 BTRFS_HEADER_FLAG_RELOC);
211 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
212 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
213 else
214 btrfs_set_header_owner(cow, new_root_objectid);
215
216 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
217
218 WARN_ON(btrfs_header_generation(buf) > trans->transid);
219 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
220 ret = btrfs_inc_ref(trans, root, cow, 1);
221 else
222 ret = btrfs_inc_ref(trans, root, cow, 0);
223
224 if (ret)
225 return ret;
226
227 btrfs_mark_buffer_dirty(cow);
228 *cow_ret = cow;
229 return 0;
230}
231
232enum mod_log_op {
233 MOD_LOG_KEY_REPLACE,
234 MOD_LOG_KEY_ADD,
235 MOD_LOG_KEY_REMOVE,
236 MOD_LOG_KEY_REMOVE_WHILE_FREEING,
237 MOD_LOG_KEY_REMOVE_WHILE_MOVING,
238 MOD_LOG_MOVE_KEYS,
239 MOD_LOG_ROOT_REPLACE,
240};
241
242struct tree_mod_root {
243 u64 logical;
244 u8 level;
245};
246
247struct tree_mod_elem {
248 struct rb_node node;
249 u64 logical;
250 u64 seq;
251 enum mod_log_op op;
252
253 /* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
254 int slot;
255
256 /* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
257 u64 generation;
258
259 /* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
260 struct btrfs_disk_key key;
261 u64 blockptr;
262
263 /* this is used for op == MOD_LOG_MOVE_KEYS */
264 struct {
265 int dst_slot;
266 int nr_items;
267 } move;
268
269 /* this is used for op == MOD_LOG_ROOT_REPLACE */
270 struct tree_mod_root old_root;
271};
272
273/*
274 * Pull a new tree mod seq number for our operation.
275 */
276static inline u64 btrfs_inc_tree_mod_seq(struct btrfs_fs_info *fs_info)
277{
278 return atomic64_inc_return(&fs_info->tree_mod_seq);
279}
280
281/*
282 * This adds a new blocker to the tree mod log's blocker list if the @elem
283 * passed does not already have a sequence number set. So when a caller expects
284 * to record tree modifications, it should ensure to set elem->seq to zero
285 * before calling btrfs_get_tree_mod_seq.
286 * Returns a fresh, unused tree log modification sequence number, even if no new
287 * blocker was added.
288 */
289u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
290 struct seq_list *elem)
291{
292 write_lock(&fs_info->tree_mod_log_lock);
293 if (!elem->seq) {
294 elem->seq = btrfs_inc_tree_mod_seq(fs_info);
295 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
296 }
297 write_unlock(&fs_info->tree_mod_log_lock);
298
299 return elem->seq;
300}
301
302void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
303 struct seq_list *elem)
304{
305 struct rb_root *tm_root;
306 struct rb_node *node;
307 struct rb_node *next;
308 struct tree_mod_elem *tm;
309 u64 min_seq = (u64)-1;
310 u64 seq_putting = elem->seq;
311
312 if (!seq_putting)
313 return;
314
315 write_lock(&fs_info->tree_mod_log_lock);
316 list_del(&elem->list);
317 elem->seq = 0;
318
319 if (!list_empty(&fs_info->tree_mod_seq_list)) {
320 struct seq_list *first;
321
322 first = list_first_entry(&fs_info->tree_mod_seq_list,
323 struct seq_list, list);
324 if (seq_putting > first->seq) {
325 /*
326 * Blocker with lower sequence number exists, we
327 * cannot remove anything from the log.
328 */
329 write_unlock(&fs_info->tree_mod_log_lock);
330 return;
331 }
332 min_seq = first->seq;
333 }
334
335 /*
336 * anything that's lower than the lowest existing (read: blocked)
337 * sequence number can be removed from the tree.
338 */
339 tm_root = &fs_info->tree_mod_log;
340 for (node = rb_first(tm_root); node; node = next) {
341 next = rb_next(node);
342 tm = rb_entry(node, struct tree_mod_elem, node);
343 if (tm->seq >= min_seq)
344 continue;
345 rb_erase(node, tm_root);
346 kfree(tm);
347 }
348 write_unlock(&fs_info->tree_mod_log_lock);
349}
350
351/*
352 * key order of the log:
353 * node/leaf start address -> sequence
354 *
355 * The 'start address' is the logical address of the *new* root node
356 * for root replace operations, or the logical address of the affected
357 * block for all other operations.
358 */
359static noinline int
360__tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
361{
362 struct rb_root *tm_root;
363 struct rb_node **new;
364 struct rb_node *parent = NULL;
365 struct tree_mod_elem *cur;
366
367 lockdep_assert_held_write(&fs_info->tree_mod_log_lock);
368
369 tm->seq = btrfs_inc_tree_mod_seq(fs_info);
370
371 tm_root = &fs_info->tree_mod_log;
372 new = &tm_root->rb_node;
373 while (*new) {
374 cur = rb_entry(*new, struct tree_mod_elem, node);
375 parent = *new;
376 if (cur->logical < tm->logical)
377 new = &((*new)->rb_left);
378 else if (cur->logical > tm->logical)
379 new = &((*new)->rb_right);
380 else if (cur->seq < tm->seq)
381 new = &((*new)->rb_left);
382 else if (cur->seq > tm->seq)
383 new = &((*new)->rb_right);
384 else
385 return -EEXIST;
386 }
387
388 rb_link_node(&tm->node, parent, new);
389 rb_insert_color(&tm->node, tm_root);
390 return 0;
391}
392
393/*
394 * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it
395 * returns zero with the tree_mod_log_lock acquired. The caller must hold
396 * this until all tree mod log insertions are recorded in the rb tree and then
397 * write unlock fs_info::tree_mod_log_lock.
398 */
399static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
400 struct extent_buffer *eb) {
401 smp_mb();
402 if (list_empty(&(fs_info)->tree_mod_seq_list))
403 return 1;
404 if (eb && btrfs_header_level(eb) == 0)
405 return 1;
406
407 write_lock(&fs_info->tree_mod_log_lock);
408 if (list_empty(&(fs_info)->tree_mod_seq_list)) {
409 write_unlock(&fs_info->tree_mod_log_lock);
410 return 1;
411 }
412
413 return 0;
414}
415
416/* Similar to tree_mod_dont_log, but doesn't acquire any locks. */
417static inline int tree_mod_need_log(const struct btrfs_fs_info *fs_info,
418 struct extent_buffer *eb)
419{
420 smp_mb();
421 if (list_empty(&(fs_info)->tree_mod_seq_list))
422 return 0;
423 if (eb && btrfs_header_level(eb) == 0)
424 return 0;
425
426 return 1;
427}
428
429static struct tree_mod_elem *
430alloc_tree_mod_elem(struct extent_buffer *eb, int slot,
431 enum mod_log_op op, gfp_t flags)
432{
433 struct tree_mod_elem *tm;
434
435 tm = kzalloc(sizeof(*tm), flags);
436 if (!tm)
437 return NULL;
438
439 tm->logical = eb->start;
440 if (op != MOD_LOG_KEY_ADD) {
441 btrfs_node_key(eb, &tm->key, slot);
442 tm->blockptr = btrfs_node_blockptr(eb, slot);
443 }
444 tm->op = op;
445 tm->slot = slot;
446 tm->generation = btrfs_node_ptr_generation(eb, slot);
447 RB_CLEAR_NODE(&tm->node);
448
449 return tm;
450}
451
452static noinline int tree_mod_log_insert_key(struct extent_buffer *eb, int slot,
453 enum mod_log_op op, gfp_t flags)
454{
455 struct tree_mod_elem *tm;
456 int ret;
457
458 if (!tree_mod_need_log(eb->fs_info, eb))
459 return 0;
460
461 tm = alloc_tree_mod_elem(eb, slot, op, flags);
462 if (!tm)
463 return -ENOMEM;
464
465 if (tree_mod_dont_log(eb->fs_info, eb)) {
466 kfree(tm);
467 return 0;
468 }
469
470 ret = __tree_mod_log_insert(eb->fs_info, tm);
471 write_unlock(&eb->fs_info->tree_mod_log_lock);
472 if (ret)
473 kfree(tm);
474
475 return ret;
476}
477
478static noinline int tree_mod_log_insert_move(struct extent_buffer *eb,
479 int dst_slot, int src_slot, int nr_items)
480{
481 struct tree_mod_elem *tm = NULL;
482 struct tree_mod_elem **tm_list = NULL;
483 int ret = 0;
484 int i;
485 int locked = 0;
486
487 if (!tree_mod_need_log(eb->fs_info, eb))
488 return 0;
489
490 tm_list = kcalloc(nr_items, sizeof(struct tree_mod_elem *), GFP_NOFS);
491 if (!tm_list)
492 return -ENOMEM;
493
494 tm = kzalloc(sizeof(*tm), GFP_NOFS);
495 if (!tm) {
496 ret = -ENOMEM;
497 goto free_tms;
498 }
499
500 tm->logical = eb->start;
501 tm->slot = src_slot;
502 tm->move.dst_slot = dst_slot;
503 tm->move.nr_items = nr_items;
504 tm->op = MOD_LOG_MOVE_KEYS;
505
506 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
507 tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot,
508 MOD_LOG_KEY_REMOVE_WHILE_MOVING, GFP_NOFS);
509 if (!tm_list[i]) {
510 ret = -ENOMEM;
511 goto free_tms;
512 }
513 }
514
515 if (tree_mod_dont_log(eb->fs_info, eb))
516 goto free_tms;
517 locked = 1;
518
519 /*
520 * When we override something during the move, we log these removals.
521 * This can only happen when we move towards the beginning of the
522 * buffer, i.e. dst_slot < src_slot.
523 */
524 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
525 ret = __tree_mod_log_insert(eb->fs_info, tm_list[i]);
526 if (ret)
527 goto free_tms;
528 }
529
530 ret = __tree_mod_log_insert(eb->fs_info, tm);
531 if (ret)
532 goto free_tms;
533 write_unlock(&eb->fs_info->tree_mod_log_lock);
534 kfree(tm_list);
535
536 return 0;
537free_tms:
538 for (i = 0; i < nr_items; i++) {
539 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
540 rb_erase(&tm_list[i]->node, &eb->fs_info->tree_mod_log);
541 kfree(tm_list[i]);
542 }
543 if (locked)
544 write_unlock(&eb->fs_info->tree_mod_log_lock);
545 kfree(tm_list);
546 kfree(tm);
547
548 return ret;
549}
550
551static inline int
552__tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
553 struct tree_mod_elem **tm_list,
554 int nritems)
555{
556 int i, j;
557 int ret;
558
559 for (i = nritems - 1; i >= 0; i--) {
560 ret = __tree_mod_log_insert(fs_info, tm_list[i]);
561 if (ret) {
562 for (j = nritems - 1; j > i; j--)
563 rb_erase(&tm_list[j]->node,
564 &fs_info->tree_mod_log);
565 return ret;
566 }
567 }
568
569 return 0;
570}
571
572static noinline int tree_mod_log_insert_root(struct extent_buffer *old_root,
573 struct extent_buffer *new_root, int log_removal)
574{
575 struct btrfs_fs_info *fs_info = old_root->fs_info;
576 struct tree_mod_elem *tm = NULL;
577 struct tree_mod_elem **tm_list = NULL;
578 int nritems = 0;
579 int ret = 0;
580 int i;
581
582 if (!tree_mod_need_log(fs_info, NULL))
583 return 0;
584
585 if (log_removal && btrfs_header_level(old_root) > 0) {
586 nritems = btrfs_header_nritems(old_root);
587 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *),
588 GFP_NOFS);
589 if (!tm_list) {
590 ret = -ENOMEM;
591 goto free_tms;
592 }
593 for (i = 0; i < nritems; i++) {
594 tm_list[i] = alloc_tree_mod_elem(old_root, i,
595 MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
596 if (!tm_list[i]) {
597 ret = -ENOMEM;
598 goto free_tms;
599 }
600 }
601 }
602
603 tm = kzalloc(sizeof(*tm), GFP_NOFS);
604 if (!tm) {
605 ret = -ENOMEM;
606 goto free_tms;
607 }
608
609 tm->logical = new_root->start;
610 tm->old_root.logical = old_root->start;
611 tm->old_root.level = btrfs_header_level(old_root);
612 tm->generation = btrfs_header_generation(old_root);
613 tm->op = MOD_LOG_ROOT_REPLACE;
614
615 if (tree_mod_dont_log(fs_info, NULL))
616 goto free_tms;
617
618 if (tm_list)
619 ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
620 if (!ret)
621 ret = __tree_mod_log_insert(fs_info, tm);
622
623 write_unlock(&fs_info->tree_mod_log_lock);
624 if (ret)
625 goto free_tms;
626 kfree(tm_list);
627
628 return ret;
629
630free_tms:
631 if (tm_list) {
632 for (i = 0; i < nritems; i++)
633 kfree(tm_list[i]);
634 kfree(tm_list);
635 }
636 kfree(tm);
637
638 return ret;
639}
640
641static struct tree_mod_elem *
642__tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
643 int smallest)
644{
645 struct rb_root *tm_root;
646 struct rb_node *node;
647 struct tree_mod_elem *cur = NULL;
648 struct tree_mod_elem *found = NULL;
649
650 read_lock(&fs_info->tree_mod_log_lock);
651 tm_root = &fs_info->tree_mod_log;
652 node = tm_root->rb_node;
653 while (node) {
654 cur = rb_entry(node, struct tree_mod_elem, node);
655 if (cur->logical < start) {
656 node = node->rb_left;
657 } else if (cur->logical > start) {
658 node = node->rb_right;
659 } else if (cur->seq < min_seq) {
660 node = node->rb_left;
661 } else if (!smallest) {
662 /* we want the node with the highest seq */
663 if (found)
664 BUG_ON(found->seq > cur->seq);
665 found = cur;
666 node = node->rb_left;
667 } else if (cur->seq > min_seq) {
668 /* we want the node with the smallest seq */
669 if (found)
670 BUG_ON(found->seq < cur->seq);
671 found = cur;
672 node = node->rb_right;
673 } else {
674 found = cur;
675 break;
676 }
677 }
678 read_unlock(&fs_info->tree_mod_log_lock);
679
680 return found;
681}
682
683/*
684 * this returns the element from the log with the smallest time sequence
685 * value that's in the log (the oldest log item). any element with a time
686 * sequence lower than min_seq will be ignored.
687 */
688static struct tree_mod_elem *
689tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
690 u64 min_seq)
691{
692 return __tree_mod_log_search(fs_info, start, min_seq, 1);
693}
694
695/*
696 * this returns the element from the log with the largest time sequence
697 * value that's in the log (the most recent log item). any element with
698 * a time sequence lower than min_seq will be ignored.
699 */
700static struct tree_mod_elem *
701tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
702{
703 return __tree_mod_log_search(fs_info, start, min_seq, 0);
704}
705
706static noinline int tree_mod_log_eb_copy(struct extent_buffer *dst,
707 struct extent_buffer *src, unsigned long dst_offset,
708 unsigned long src_offset, int nr_items)
709{
710 struct btrfs_fs_info *fs_info = dst->fs_info;
711 int ret = 0;
712 struct tree_mod_elem **tm_list = NULL;
713 struct tree_mod_elem **tm_list_add, **tm_list_rem;
714 int i;
715 int locked = 0;
716
717 if (!tree_mod_need_log(fs_info, NULL))
718 return 0;
719
720 if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
721 return 0;
722
723 tm_list = kcalloc(nr_items * 2, sizeof(struct tree_mod_elem *),
724 GFP_NOFS);
725 if (!tm_list)
726 return -ENOMEM;
727
728 tm_list_add = tm_list;
729 tm_list_rem = tm_list + nr_items;
730 for (i = 0; i < nr_items; i++) {
731 tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset,
732 MOD_LOG_KEY_REMOVE, GFP_NOFS);
733 if (!tm_list_rem[i]) {
734 ret = -ENOMEM;
735 goto free_tms;
736 }
737
738 tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset,
739 MOD_LOG_KEY_ADD, GFP_NOFS);
740 if (!tm_list_add[i]) {
741 ret = -ENOMEM;
742 goto free_tms;
743 }
744 }
745
746 if (tree_mod_dont_log(fs_info, NULL))
747 goto free_tms;
748 locked = 1;
749
750 for (i = 0; i < nr_items; i++) {
751 ret = __tree_mod_log_insert(fs_info, tm_list_rem[i]);
752 if (ret)
753 goto free_tms;
754 ret = __tree_mod_log_insert(fs_info, tm_list_add[i]);
755 if (ret)
756 goto free_tms;
757 }
758
759 write_unlock(&fs_info->tree_mod_log_lock);
760 kfree(tm_list);
761
762 return 0;
763
764free_tms:
765 for (i = 0; i < nr_items * 2; i++) {
766 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
767 rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
768 kfree(tm_list[i]);
769 }
770 if (locked)
771 write_unlock(&fs_info->tree_mod_log_lock);
772 kfree(tm_list);
773
774 return ret;
775}
776
777static noinline int tree_mod_log_free_eb(struct extent_buffer *eb)
778{
779 struct tree_mod_elem **tm_list = NULL;
780 int nritems = 0;
781 int i;
782 int ret = 0;
783
784 if (btrfs_header_level(eb) == 0)
785 return 0;
786
787 if (!tree_mod_need_log(eb->fs_info, NULL))
788 return 0;
789
790 nritems = btrfs_header_nritems(eb);
791 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *), GFP_NOFS);
792 if (!tm_list)
793 return -ENOMEM;
794
795 for (i = 0; i < nritems; i++) {
796 tm_list[i] = alloc_tree_mod_elem(eb, i,
797 MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
798 if (!tm_list[i]) {
799 ret = -ENOMEM;
800 goto free_tms;
801 }
802 }
803
804 if (tree_mod_dont_log(eb->fs_info, eb))
805 goto free_tms;
806
807 ret = __tree_mod_log_free_eb(eb->fs_info, tm_list, nritems);
808 write_unlock(&eb->fs_info->tree_mod_log_lock);
809 if (ret)
810 goto free_tms;
811 kfree(tm_list);
812
813 return 0;
814
815free_tms:
816 for (i = 0; i < nritems; i++)
817 kfree(tm_list[i]);
818 kfree(tm_list);
819
820 return ret;
821}
822
823/*
824 * check if the tree block can be shared by multiple trees
825 */
826int btrfs_block_can_be_shared(struct btrfs_root *root,
827 struct extent_buffer *buf)
828{
829 /*
830 * Tree blocks not in shareable trees and tree roots are never shared.
831 * If a block was allocated after the last snapshot and the block was
832 * not allocated by tree relocation, we know the block is not shared.
833 */
834 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
835 buf != root->node && buf != root->commit_root &&
836 (btrfs_header_generation(buf) <=
837 btrfs_root_last_snapshot(&root->root_item) ||
838 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
839 return 1;
840
841 return 0;
842}
843
844static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
845 struct btrfs_root *root,
846 struct extent_buffer *buf,
847 struct extent_buffer *cow,
848 int *last_ref)
849{
850 struct btrfs_fs_info *fs_info = root->fs_info;
851 u64 refs;
852 u64 owner;
853 u64 flags;
854 u64 new_flags = 0;
855 int ret;
856
857 /*
858 * Backrefs update rules:
859 *
860 * Always use full backrefs for extent pointers in tree block
861 * allocated by tree relocation.
862 *
863 * If a shared tree block is no longer referenced by its owner
864 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
865 * use full backrefs for extent pointers in tree block.
866 *
867 * If a tree block is been relocating
868 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
869 * use full backrefs for extent pointers in tree block.
870 * The reason for this is some operations (such as drop tree)
871 * are only allowed for blocks use full backrefs.
872 */
873
874 if (btrfs_block_can_be_shared(root, buf)) {
875 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
876 btrfs_header_level(buf), 1,
877 &refs, &flags);
878 if (ret)
879 return ret;
880 if (refs == 0) {
881 ret = -EROFS;
882 btrfs_handle_fs_error(fs_info, ret, NULL);
883 return ret;
884 }
885 } else {
886 refs = 1;
887 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
888 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
889 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
890 else
891 flags = 0;
892 }
893
894 owner = btrfs_header_owner(buf);
895 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
896 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
897
898 if (refs > 1) {
899 if ((owner == root->root_key.objectid ||
900 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
901 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
902 ret = btrfs_inc_ref(trans, root, buf, 1);
903 if (ret)
904 return ret;
905
906 if (root->root_key.objectid ==
907 BTRFS_TREE_RELOC_OBJECTID) {
908 ret = btrfs_dec_ref(trans, root, buf, 0);
909 if (ret)
910 return ret;
911 ret = btrfs_inc_ref(trans, root, cow, 1);
912 if (ret)
913 return ret;
914 }
915 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
916 } else {
917
918 if (root->root_key.objectid ==
919 BTRFS_TREE_RELOC_OBJECTID)
920 ret = btrfs_inc_ref(trans, root, cow, 1);
921 else
922 ret = btrfs_inc_ref(trans, root, cow, 0);
923 if (ret)
924 return ret;
925 }
926 if (new_flags != 0) {
927 int level = btrfs_header_level(buf);
928
929 ret = btrfs_set_disk_extent_flags(trans, buf,
930 new_flags, level, 0);
931 if (ret)
932 return ret;
933 }
934 } else {
935 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
936 if (root->root_key.objectid ==
937 BTRFS_TREE_RELOC_OBJECTID)
938 ret = btrfs_inc_ref(trans, root, cow, 1);
939 else
940 ret = btrfs_inc_ref(trans, root, cow, 0);
941 if (ret)
942 return ret;
943 ret = btrfs_dec_ref(trans, root, buf, 1);
944 if (ret)
945 return ret;
946 }
947 btrfs_clean_tree_block(buf);
948 *last_ref = 1;
949 }
950 return 0;
951}
952
953static struct extent_buffer *alloc_tree_block_no_bg_flush(
954 struct btrfs_trans_handle *trans,
955 struct btrfs_root *root,
956 u64 parent_start,
957 const struct btrfs_disk_key *disk_key,
958 int level,
959 u64 hint,
960 u64 empty_size)
961{
962 struct btrfs_fs_info *fs_info = root->fs_info;
963 struct extent_buffer *ret;
964
965 /*
966 * If we are COWing a node/leaf from the extent, chunk, device or free
967 * space trees, make sure that we do not finish block group creation of
968 * pending block groups. We do this to avoid a deadlock.
969 * COWing can result in allocation of a new chunk, and flushing pending
970 * block groups (btrfs_create_pending_block_groups()) can be triggered
971 * when finishing allocation of a new chunk. Creation of a pending block
972 * group modifies the extent, chunk, device and free space trees,
973 * therefore we could deadlock with ourselves since we are holding a
974 * lock on an extent buffer that btrfs_create_pending_block_groups() may
975 * try to COW later.
976 * For similar reasons, we also need to delay flushing pending block
977 * groups when splitting a leaf or node, from one of those trees, since
978 * we are holding a write lock on it and its parent or when inserting a
979 * new root node for one of those trees.
980 */
981 if (root == fs_info->extent_root ||
982 root == fs_info->chunk_root ||
983 root == fs_info->dev_root ||
984 root == fs_info->free_space_root)
985 trans->can_flush_pending_bgs = false;
986
987 ret = btrfs_alloc_tree_block(trans, root, parent_start,
988 root->root_key.objectid, disk_key, level,
989 hint, empty_size);
990 trans->can_flush_pending_bgs = true;
991
992 return ret;
993}
994
995/*
996 * does the dirty work in cow of a single block. The parent block (if
997 * supplied) is updated to point to the new cow copy. The new buffer is marked
998 * dirty and returned locked. If you modify the block it needs to be marked
999 * dirty again.
1000 *
1001 * search_start -- an allocation hint for the new block
1002 *
1003 * empty_size -- a hint that you plan on doing more cow. This is the size in
1004 * bytes the allocator should try to find free next to the block it returns.
1005 * This is just a hint and may be ignored by the allocator.
1006 */
1007static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
1008 struct btrfs_root *root,
1009 struct extent_buffer *buf,
1010 struct extent_buffer *parent, int parent_slot,
1011 struct extent_buffer **cow_ret,
1012 u64 search_start, u64 empty_size)
1013{
1014 struct btrfs_fs_info *fs_info = root->fs_info;
1015 struct btrfs_disk_key disk_key;
1016 struct extent_buffer *cow;
1017 int level, ret;
1018 int last_ref = 0;
1019 int unlock_orig = 0;
1020 u64 parent_start = 0;
1021
1022 if (*cow_ret == buf)
1023 unlock_orig = 1;
1024
1025 btrfs_assert_tree_locked(buf);
1026
1027 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
1028 trans->transid != fs_info->running_transaction->transid);
1029 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
1030 trans->transid != root->last_trans);
1031
1032 level = btrfs_header_level(buf);
1033
1034 if (level == 0)
1035 btrfs_item_key(buf, &disk_key, 0);
1036 else
1037 btrfs_node_key(buf, &disk_key, 0);
1038
1039 if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
1040 parent_start = parent->start;
1041
1042 cow = alloc_tree_block_no_bg_flush(trans, root, parent_start, &disk_key,
1043 level, search_start, empty_size);
1044 if (IS_ERR(cow))
1045 return PTR_ERR(cow);
1046
1047 /* cow is set to blocking by btrfs_init_new_buffer */
1048
1049 copy_extent_buffer_full(cow, buf);
1050 btrfs_set_header_bytenr(cow, cow->start);
1051 btrfs_set_header_generation(cow, trans->transid);
1052 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
1053 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
1054 BTRFS_HEADER_FLAG_RELOC);
1055 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1056 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
1057 else
1058 btrfs_set_header_owner(cow, root->root_key.objectid);
1059
1060 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
1061
1062 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
1063 if (ret) {
1064 btrfs_abort_transaction(trans, ret);
1065 return ret;
1066 }
1067
1068 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
1069 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
1070 if (ret) {
1071 btrfs_abort_transaction(trans, ret);
1072 return ret;
1073 }
1074 }
1075
1076 if (buf == root->node) {
1077 WARN_ON(parent && parent != buf);
1078 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1079 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1080 parent_start = buf->start;
1081
1082 atomic_inc(&cow->refs);
1083 ret = tree_mod_log_insert_root(root->node, cow, 1);
1084 BUG_ON(ret < 0);
1085 rcu_assign_pointer(root->node, cow);
1086
1087 btrfs_free_tree_block(trans, root, buf, parent_start,
1088 last_ref);
1089 free_extent_buffer(buf);
1090 add_root_to_dirty_list(root);
1091 } else {
1092 WARN_ON(trans->transid != btrfs_header_generation(parent));
1093 tree_mod_log_insert_key(parent, parent_slot,
1094 MOD_LOG_KEY_REPLACE, GFP_NOFS);
1095 btrfs_set_node_blockptr(parent, parent_slot,
1096 cow->start);
1097 btrfs_set_node_ptr_generation(parent, parent_slot,
1098 trans->transid);
1099 btrfs_mark_buffer_dirty(parent);
1100 if (last_ref) {
1101 ret = tree_mod_log_free_eb(buf);
1102 if (ret) {
1103 btrfs_abort_transaction(trans, ret);
1104 return ret;
1105 }
1106 }
1107 btrfs_free_tree_block(trans, root, buf, parent_start,
1108 last_ref);
1109 }
1110 if (unlock_orig)
1111 btrfs_tree_unlock(buf);
1112 free_extent_buffer_stale(buf);
1113 btrfs_mark_buffer_dirty(cow);
1114 *cow_ret = cow;
1115 return 0;
1116}
1117
1118/*
1119 * returns the logical address of the oldest predecessor of the given root.
1120 * entries older than time_seq are ignored.
1121 */
1122static struct tree_mod_elem *__tree_mod_log_oldest_root(
1123 struct extent_buffer *eb_root, u64 time_seq)
1124{
1125 struct tree_mod_elem *tm;
1126 struct tree_mod_elem *found = NULL;
1127 u64 root_logical = eb_root->start;
1128 int looped = 0;
1129
1130 if (!time_seq)
1131 return NULL;
1132
1133 /*
1134 * the very last operation that's logged for a root is the
1135 * replacement operation (if it is replaced at all). this has
1136 * the logical address of the *new* root, making it the very
1137 * first operation that's logged for this root.
1138 */
1139 while (1) {
1140 tm = tree_mod_log_search_oldest(eb_root->fs_info, root_logical,
1141 time_seq);
1142 if (!looped && !tm)
1143 return NULL;
1144 /*
1145 * if there are no tree operation for the oldest root, we simply
1146 * return it. this should only happen if that (old) root is at
1147 * level 0.
1148 */
1149 if (!tm)
1150 break;
1151
1152 /*
1153 * if there's an operation that's not a root replacement, we
1154 * found the oldest version of our root. normally, we'll find a
1155 * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1156 */
1157 if (tm->op != MOD_LOG_ROOT_REPLACE)
1158 break;
1159
1160 found = tm;
1161 root_logical = tm->old_root.logical;
1162 looped = 1;
1163 }
1164
1165 /* if there's no old root to return, return what we found instead */
1166 if (!found)
1167 found = tm;
1168
1169 return found;
1170}
1171
1172/*
1173 * tm is a pointer to the first operation to rewind within eb. then, all
1174 * previous operations will be rewound (until we reach something older than
1175 * time_seq).
1176 */
1177static void
1178__tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1179 u64 time_seq, struct tree_mod_elem *first_tm)
1180{
1181 u32 n;
1182 struct rb_node *next;
1183 struct tree_mod_elem *tm = first_tm;
1184 unsigned long o_dst;
1185 unsigned long o_src;
1186 unsigned long p_size = sizeof(struct btrfs_key_ptr);
1187
1188 n = btrfs_header_nritems(eb);
1189 read_lock(&fs_info->tree_mod_log_lock);
1190 while (tm && tm->seq >= time_seq) {
1191 /*
1192 * all the operations are recorded with the operator used for
1193 * the modification. as we're going backwards, we do the
1194 * opposite of each operation here.
1195 */
1196 switch (tm->op) {
1197 case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1198 BUG_ON(tm->slot < n);
1199 fallthrough;
1200 case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1201 case MOD_LOG_KEY_REMOVE:
1202 btrfs_set_node_key(eb, &tm->key, tm->slot);
1203 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1204 btrfs_set_node_ptr_generation(eb, tm->slot,
1205 tm->generation);
1206 n++;
1207 break;
1208 case MOD_LOG_KEY_REPLACE:
1209 BUG_ON(tm->slot >= n);
1210 btrfs_set_node_key(eb, &tm->key, tm->slot);
1211 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1212 btrfs_set_node_ptr_generation(eb, tm->slot,
1213 tm->generation);
1214 break;
1215 case MOD_LOG_KEY_ADD:
1216 /* if a move operation is needed it's in the log */
1217 n--;
1218 break;
1219 case MOD_LOG_MOVE_KEYS:
1220 o_dst = btrfs_node_key_ptr_offset(tm->slot);
1221 o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1222 memmove_extent_buffer(eb, o_dst, o_src,
1223 tm->move.nr_items * p_size);
1224 break;
1225 case MOD_LOG_ROOT_REPLACE:
1226 /*
1227 * this operation is special. for roots, this must be
1228 * handled explicitly before rewinding.
1229 * for non-roots, this operation may exist if the node
1230 * was a root: root A -> child B; then A gets empty and
1231 * B is promoted to the new root. in the mod log, we'll
1232 * have a root-replace operation for B, a tree block
1233 * that is no root. we simply ignore that operation.
1234 */
1235 break;
1236 }
1237 next = rb_next(&tm->node);
1238 if (!next)
1239 break;
1240 tm = rb_entry(next, struct tree_mod_elem, node);
1241 if (tm->logical != first_tm->logical)
1242 break;
1243 }
1244 read_unlock(&fs_info->tree_mod_log_lock);
1245 btrfs_set_header_nritems(eb, n);
1246}
1247
1248/*
1249 * Called with eb read locked. If the buffer cannot be rewound, the same buffer
1250 * is returned. If rewind operations happen, a fresh buffer is returned. The
1251 * returned buffer is always read-locked. If the returned buffer is not the
1252 * input buffer, the lock on the input buffer is released and the input buffer
1253 * is freed (its refcount is decremented).
1254 */
1255static struct extent_buffer *
1256tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
1257 struct extent_buffer *eb, u64 time_seq)
1258{
1259 struct extent_buffer *eb_rewin;
1260 struct tree_mod_elem *tm;
1261
1262 if (!time_seq)
1263 return eb;
1264
1265 if (btrfs_header_level(eb) == 0)
1266 return eb;
1267
1268 tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1269 if (!tm)
1270 return eb;
1271
1272 btrfs_set_path_blocking(path);
1273 btrfs_set_lock_blocking_read(eb);
1274
1275 if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1276 BUG_ON(tm->slot != 0);
1277 eb_rewin = alloc_dummy_extent_buffer(fs_info, eb->start);
1278 if (!eb_rewin) {
1279 btrfs_tree_read_unlock_blocking(eb);
1280 free_extent_buffer(eb);
1281 return NULL;
1282 }
1283 btrfs_set_header_bytenr(eb_rewin, eb->start);
1284 btrfs_set_header_backref_rev(eb_rewin,
1285 btrfs_header_backref_rev(eb));
1286 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1287 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1288 } else {
1289 eb_rewin = btrfs_clone_extent_buffer(eb);
1290 if (!eb_rewin) {
1291 btrfs_tree_read_unlock_blocking(eb);
1292 free_extent_buffer(eb);
1293 return NULL;
1294 }
1295 }
1296
1297 btrfs_tree_read_unlock_blocking(eb);
1298 free_extent_buffer(eb);
1299
1300 btrfs_set_buffer_lockdep_class(btrfs_header_owner(eb_rewin),
1301 eb_rewin, btrfs_header_level(eb_rewin));
1302 btrfs_tree_read_lock(eb_rewin);
1303 __tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm);
1304 WARN_ON(btrfs_header_nritems(eb_rewin) >
1305 BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1306
1307 return eb_rewin;
1308}
1309
1310/*
1311 * get_old_root() rewinds the state of @root's root node to the given @time_seq
1312 * value. If there are no changes, the current root->root_node is returned. If
1313 * anything changed in between, there's a fresh buffer allocated on which the
1314 * rewind operations are done. In any case, the returned buffer is read locked.
1315 * Returns NULL on error (with no locks held).
1316 */
1317static inline struct extent_buffer *
1318get_old_root(struct btrfs_root *root, u64 time_seq)
1319{
1320 struct btrfs_fs_info *fs_info = root->fs_info;
1321 struct tree_mod_elem *tm;
1322 struct extent_buffer *eb = NULL;
1323 struct extent_buffer *eb_root;
1324 u64 eb_root_owner = 0;
1325 struct extent_buffer *old;
1326 struct tree_mod_root *old_root = NULL;
1327 u64 old_generation = 0;
1328 u64 logical;
1329 int level;
1330
1331 eb_root = btrfs_read_lock_root_node(root);
1332 tm = __tree_mod_log_oldest_root(eb_root, time_seq);
1333 if (!tm)
1334 return eb_root;
1335
1336 if (tm->op == MOD_LOG_ROOT_REPLACE) {
1337 old_root = &tm->old_root;
1338 old_generation = tm->generation;
1339 logical = old_root->logical;
1340 level = old_root->level;
1341 } else {
1342 logical = eb_root->start;
1343 level = btrfs_header_level(eb_root);
1344 }
1345
1346 tm = tree_mod_log_search(fs_info, logical, time_seq);
1347 if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1348 btrfs_tree_read_unlock(eb_root);
1349 free_extent_buffer(eb_root);
1350 old = read_tree_block(fs_info, logical, 0, level, NULL);
1351 if (WARN_ON(IS_ERR(old) || !extent_buffer_uptodate(old))) {
1352 if (!IS_ERR(old))
1353 free_extent_buffer(old);
1354 btrfs_warn(fs_info,
1355 "failed to read tree block %llu from get_old_root",
1356 logical);
1357 } else {
1358 eb = btrfs_clone_extent_buffer(old);
1359 free_extent_buffer(old);
1360 }
1361 } else if (old_root) {
1362 eb_root_owner = btrfs_header_owner(eb_root);
1363 btrfs_tree_read_unlock(eb_root);
1364 free_extent_buffer(eb_root);
1365 eb = alloc_dummy_extent_buffer(fs_info, logical);
1366 } else {
1367 btrfs_set_lock_blocking_read(eb_root);
1368 eb = btrfs_clone_extent_buffer(eb_root);
1369 btrfs_tree_read_unlock_blocking(eb_root);
1370 free_extent_buffer(eb_root);
1371 }
1372
1373 if (!eb)
1374 return NULL;
1375 if (old_root) {
1376 btrfs_set_header_bytenr(eb, eb->start);
1377 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1378 btrfs_set_header_owner(eb, eb_root_owner);
1379 btrfs_set_header_level(eb, old_root->level);
1380 btrfs_set_header_generation(eb, old_generation);
1381 }
1382 btrfs_set_buffer_lockdep_class(btrfs_header_owner(eb), eb,
1383 btrfs_header_level(eb));
1384 btrfs_tree_read_lock(eb);
1385 if (tm)
1386 __tree_mod_log_rewind(fs_info, eb, time_seq, tm);
1387 else
1388 WARN_ON(btrfs_header_level(eb) != 0);
1389 WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1390
1391 return eb;
1392}
1393
1394int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
1395{
1396 struct tree_mod_elem *tm;
1397 int level;
1398 struct extent_buffer *eb_root = btrfs_root_node(root);
1399
1400 tm = __tree_mod_log_oldest_root(eb_root, time_seq);
1401 if (tm && tm->op == MOD_LOG_ROOT_REPLACE) {
1402 level = tm->old_root.level;
1403 } else {
1404 level = btrfs_header_level(eb_root);
1405 }
1406 free_extent_buffer(eb_root);
1407
1408 return level;
1409}
1410
1411static inline int should_cow_block(struct btrfs_trans_handle *trans,
1412 struct btrfs_root *root,
1413 struct extent_buffer *buf)
1414{
1415 if (btrfs_is_testing(root->fs_info))
1416 return 0;
1417
1418 /* Ensure we can see the FORCE_COW bit */
1419 smp_mb__before_atomic();
1420
1421 /*
1422 * We do not need to cow a block if
1423 * 1) this block is not created or changed in this transaction;
1424 * 2) this block does not belong to TREE_RELOC tree;
1425 * 3) the root is not forced COW.
1426 *
1427 * What is forced COW:
1428 * when we create snapshot during committing the transaction,
1429 * after we've finished copying src root, we must COW the shared
1430 * block to ensure the metadata consistency.
1431 */
1432 if (btrfs_header_generation(buf) == trans->transid &&
1433 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1434 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1435 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1436 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
1437 return 0;
1438 return 1;
1439}
1440
1441/*
1442 * cows a single block, see __btrfs_cow_block for the real work.
1443 * This version of it has extra checks so that a block isn't COWed more than
1444 * once per transaction, as long as it hasn't been written yet
1445 */
1446noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1447 struct btrfs_root *root, struct extent_buffer *buf,
1448 struct extent_buffer *parent, int parent_slot,
1449 struct extent_buffer **cow_ret)
1450{
1451 struct btrfs_fs_info *fs_info = root->fs_info;
1452 u64 search_start;
1453 int ret;
1454
1455 if (test_bit(BTRFS_ROOT_DELETING, &root->state))
1456 btrfs_err(fs_info,
1457 "COW'ing blocks on a fs root that's being dropped");
1458
1459 if (trans->transaction != fs_info->running_transaction)
1460 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1461 trans->transid,
1462 fs_info->running_transaction->transid);
1463
1464 if (trans->transid != fs_info->generation)
1465 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1466 trans->transid, fs_info->generation);
1467
1468 if (!should_cow_block(trans, root, buf)) {
1469 trans->dirty = true;
1470 *cow_ret = buf;
1471 return 0;
1472 }
1473
1474 search_start = buf->start & ~((u64)SZ_1G - 1);
1475
1476 if (parent)
1477 btrfs_set_lock_blocking_write(parent);
1478 btrfs_set_lock_blocking_write(buf);
1479
1480 /*
1481 * Before CoWing this block for later modification, check if it's
1482 * the subtree root and do the delayed subtree trace if needed.
1483 *
1484 * Also We don't care about the error, as it's handled internally.
1485 */
1486 btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
1487 ret = __btrfs_cow_block(trans, root, buf, parent,
1488 parent_slot, cow_ret, search_start, 0);
1489
1490 trace_btrfs_cow_block(root, buf, *cow_ret);
1491
1492 return ret;
1493}
1494
1495/*
1496 * helper function for defrag to decide if two blocks pointed to by a
1497 * node are actually close by
1498 */
1499static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1500{
1501 if (blocknr < other && other - (blocknr + blocksize) < 32768)
1502 return 1;
1503 if (blocknr > other && blocknr - (other + blocksize) < 32768)
1504 return 1;
1505 return 0;
1506}
1507
1508#ifdef __LITTLE_ENDIAN
1509
1510/*
1511 * Compare two keys, on little-endian the disk order is same as CPU order and
1512 * we can avoid the conversion.
1513 */
1514static int comp_keys(const struct btrfs_disk_key *disk_key,
1515 const struct btrfs_key *k2)
1516{
1517 const struct btrfs_key *k1 = (const struct btrfs_key *)disk_key;
1518
1519 return btrfs_comp_cpu_keys(k1, k2);
1520}
1521
1522#else
1523
1524/*
1525 * compare two keys in a memcmp fashion
1526 */
1527static int comp_keys(const struct btrfs_disk_key *disk,
1528 const struct btrfs_key *k2)
1529{
1530 struct btrfs_key k1;
1531
1532 btrfs_disk_key_to_cpu(&k1, disk);
1533
1534 return btrfs_comp_cpu_keys(&k1, k2);
1535}
1536#endif
1537
1538/*
1539 * same as comp_keys only with two btrfs_key's
1540 */
1541int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
1542{
1543 if (k1->objectid > k2->objectid)
1544 return 1;
1545 if (k1->objectid < k2->objectid)
1546 return -1;
1547 if (k1->type > k2->type)
1548 return 1;
1549 if (k1->type < k2->type)
1550 return -1;
1551 if (k1->offset > k2->offset)
1552 return 1;
1553 if (k1->offset < k2->offset)
1554 return -1;
1555 return 0;
1556}
1557
1558/*
1559 * this is used by the defrag code to go through all the
1560 * leaves pointed to by a node and reallocate them so that
1561 * disk order is close to key order
1562 */
1563int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1564 struct btrfs_root *root, struct extent_buffer *parent,
1565 int start_slot, u64 *last_ret,
1566 struct btrfs_key *progress)
1567{
1568 struct btrfs_fs_info *fs_info = root->fs_info;
1569 struct extent_buffer *cur;
1570 u64 blocknr;
1571 u64 gen;
1572 u64 search_start = *last_ret;
1573 u64 last_block = 0;
1574 u64 other;
1575 u32 parent_nritems;
1576 int end_slot;
1577 int i;
1578 int err = 0;
1579 int parent_level;
1580 int uptodate;
1581 u32 blocksize;
1582 int progress_passed = 0;
1583 struct btrfs_disk_key disk_key;
1584
1585 parent_level = btrfs_header_level(parent);
1586
1587 WARN_ON(trans->transaction != fs_info->running_transaction);
1588 WARN_ON(trans->transid != fs_info->generation);
1589
1590 parent_nritems = btrfs_header_nritems(parent);
1591 blocksize = fs_info->nodesize;
1592 end_slot = parent_nritems - 1;
1593
1594 if (parent_nritems <= 1)
1595 return 0;
1596
1597 btrfs_set_lock_blocking_write(parent);
1598
1599 for (i = start_slot; i <= end_slot; i++) {
1600 struct btrfs_key first_key;
1601 int close = 1;
1602
1603 btrfs_node_key(parent, &disk_key, i);
1604 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1605 continue;
1606
1607 progress_passed = 1;
1608 blocknr = btrfs_node_blockptr(parent, i);
1609 gen = btrfs_node_ptr_generation(parent, i);
1610 btrfs_node_key_to_cpu(parent, &first_key, i);
1611 if (last_block == 0)
1612 last_block = blocknr;
1613
1614 if (i > 0) {
1615 other = btrfs_node_blockptr(parent, i - 1);
1616 close = close_blocks(blocknr, other, blocksize);
1617 }
1618 if (!close && i < end_slot) {
1619 other = btrfs_node_blockptr(parent, i + 1);
1620 close = close_blocks(blocknr, other, blocksize);
1621 }
1622 if (close) {
1623 last_block = blocknr;
1624 continue;
1625 }
1626
1627 cur = find_extent_buffer(fs_info, blocknr);
1628 if (cur)
1629 uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1630 else
1631 uptodate = 0;
1632 if (!cur || !uptodate) {
1633 if (!cur) {
1634 cur = read_tree_block(fs_info, blocknr, gen,
1635 parent_level - 1,
1636 &first_key);
1637 if (IS_ERR(cur)) {
1638 return PTR_ERR(cur);
1639 } else if (!extent_buffer_uptodate(cur)) {
1640 free_extent_buffer(cur);
1641 return -EIO;
1642 }
1643 } else if (!uptodate) {
1644 err = btrfs_read_buffer(cur, gen,
1645 parent_level - 1,&first_key);
1646 if (err) {
1647 free_extent_buffer(cur);
1648 return err;
1649 }
1650 }
1651 }
1652 if (search_start == 0)
1653 search_start = last_block;
1654
1655 btrfs_tree_lock(cur);
1656 btrfs_set_lock_blocking_write(cur);
1657 err = __btrfs_cow_block(trans, root, cur, parent, i,
1658 &cur, search_start,
1659 min(16 * blocksize,
1660 (end_slot - i) * blocksize));
1661 if (err) {
1662 btrfs_tree_unlock(cur);
1663 free_extent_buffer(cur);
1664 break;
1665 }
1666 search_start = cur->start;
1667 last_block = cur->start;
1668 *last_ret = search_start;
1669 btrfs_tree_unlock(cur);
1670 free_extent_buffer(cur);
1671 }
1672 return err;
1673}
1674
1675/*
1676 * search for key in the extent_buffer. The items start at offset p,
1677 * and they are item_size apart. There are 'max' items in p.
1678 *
1679 * the slot in the array is returned via slot, and it points to
1680 * the place where you would insert key if it is not found in
1681 * the array.
1682 *
1683 * slot may point to max if the key is bigger than all of the keys
1684 */
1685static noinline int generic_bin_search(struct extent_buffer *eb,
1686 unsigned long p, int item_size,
1687 const struct btrfs_key *key,
1688 int max, int *slot)
1689{
1690 int low = 0;
1691 int high = max;
1692 int ret;
1693 const int key_size = sizeof(struct btrfs_disk_key);
1694
1695 if (low > high) {
1696 btrfs_err(eb->fs_info,
1697 "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
1698 __func__, low, high, eb->start,
1699 btrfs_header_owner(eb), btrfs_header_level(eb));
1700 return -EINVAL;
1701 }
1702
1703 while (low < high) {
1704 unsigned long oip;
1705 unsigned long offset;
1706 struct btrfs_disk_key *tmp;
1707 struct btrfs_disk_key unaligned;
1708 int mid;
1709
1710 mid = (low + high) / 2;
1711 offset = p + mid * item_size;
1712 oip = offset_in_page(offset);
1713
1714 if (oip + key_size <= PAGE_SIZE) {
1715 const unsigned long idx = offset >> PAGE_SHIFT;
1716 char *kaddr = page_address(eb->pages[idx]);
1717
1718 tmp = (struct btrfs_disk_key *)(kaddr + oip);
1719 } else {
1720 read_extent_buffer(eb, &unaligned, offset, key_size);
1721 tmp = &unaligned;
1722 }
1723
1724 ret = comp_keys(tmp, key);
1725
1726 if (ret < 0)
1727 low = mid + 1;
1728 else if (ret > 0)
1729 high = mid;
1730 else {
1731 *slot = mid;
1732 return 0;
1733 }
1734 }
1735 *slot = low;
1736 return 1;
1737}
1738
1739/*
1740 * simple bin_search frontend that does the right thing for
1741 * leaves vs nodes
1742 */
1743int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
1744 int *slot)
1745{
1746 if (btrfs_header_level(eb) == 0)
1747 return generic_bin_search(eb,
1748 offsetof(struct btrfs_leaf, items),
1749 sizeof(struct btrfs_item),
1750 key, btrfs_header_nritems(eb),
1751 slot);
1752 else
1753 return generic_bin_search(eb,
1754 offsetof(struct btrfs_node, ptrs),
1755 sizeof(struct btrfs_key_ptr),
1756 key, btrfs_header_nritems(eb),
1757 slot);
1758}
1759
1760static void root_add_used(struct btrfs_root *root, u32 size)
1761{
1762 spin_lock(&root->accounting_lock);
1763 btrfs_set_root_used(&root->root_item,
1764 btrfs_root_used(&root->root_item) + size);
1765 spin_unlock(&root->accounting_lock);
1766}
1767
1768static void root_sub_used(struct btrfs_root *root, u32 size)
1769{
1770 spin_lock(&root->accounting_lock);
1771 btrfs_set_root_used(&root->root_item,
1772 btrfs_root_used(&root->root_item) - size);
1773 spin_unlock(&root->accounting_lock);
1774}
1775
1776/* given a node and slot number, this reads the blocks it points to. The
1777 * extent buffer is returned with a reference taken (but unlocked).
1778 */
1779struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
1780 int slot)
1781{
1782 int level = btrfs_header_level(parent);
1783 struct extent_buffer *eb;
1784 struct btrfs_key first_key;
1785
1786 if (slot < 0 || slot >= btrfs_header_nritems(parent))
1787 return ERR_PTR(-ENOENT);
1788
1789 BUG_ON(level == 0);
1790
1791 btrfs_node_key_to_cpu(parent, &first_key, slot);
1792 eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
1793 btrfs_node_ptr_generation(parent, slot),
1794 level - 1, &first_key);
1795 if (!IS_ERR(eb) && !extent_buffer_uptodate(eb)) {
1796 free_extent_buffer(eb);
1797 eb = ERR_PTR(-EIO);
1798 }
1799
1800 return eb;
1801}
1802
1803/*
1804 * node level balancing, used to make sure nodes are in proper order for
1805 * item deletion. We balance from the top down, so we have to make sure
1806 * that a deletion won't leave an node completely empty later on.
1807 */
1808static noinline int balance_level(struct btrfs_trans_handle *trans,
1809 struct btrfs_root *root,
1810 struct btrfs_path *path, int level)
1811{
1812 struct btrfs_fs_info *fs_info = root->fs_info;
1813 struct extent_buffer *right = NULL;
1814 struct extent_buffer *mid;
1815 struct extent_buffer *left = NULL;
1816 struct extent_buffer *parent = NULL;
1817 int ret = 0;
1818 int wret;
1819 int pslot;
1820 int orig_slot = path->slots[level];
1821 u64 orig_ptr;
1822
1823 ASSERT(level > 0);
1824
1825 mid = path->nodes[level];
1826
1827 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1828 path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1829 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1830
1831 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1832
1833 if (level < BTRFS_MAX_LEVEL - 1) {
1834 parent = path->nodes[level + 1];
1835 pslot = path->slots[level + 1];
1836 }
1837
1838 /*
1839 * deal with the case where there is only one pointer in the root
1840 * by promoting the node below to a root
1841 */
1842 if (!parent) {
1843 struct extent_buffer *child;
1844
1845 if (btrfs_header_nritems(mid) != 1)
1846 return 0;
1847
1848 /* promote the child to a root */
1849 child = btrfs_read_node_slot(mid, 0);
1850 if (IS_ERR(child)) {
1851 ret = PTR_ERR(child);
1852 btrfs_handle_fs_error(fs_info, ret, NULL);
1853 goto enospc;
1854 }
1855
1856 btrfs_tree_lock(child);
1857 btrfs_set_lock_blocking_write(child);
1858 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1859 if (ret) {
1860 btrfs_tree_unlock(child);
1861 free_extent_buffer(child);
1862 goto enospc;
1863 }
1864
1865 ret = tree_mod_log_insert_root(root->node, child, 1);
1866 BUG_ON(ret < 0);
1867 rcu_assign_pointer(root->node, child);
1868
1869 add_root_to_dirty_list(root);
1870 btrfs_tree_unlock(child);
1871
1872 path->locks[level] = 0;
1873 path->nodes[level] = NULL;
1874 btrfs_clean_tree_block(mid);
1875 btrfs_tree_unlock(mid);
1876 /* once for the path */
1877 free_extent_buffer(mid);
1878
1879 root_sub_used(root, mid->len);
1880 btrfs_free_tree_block(trans, root, mid, 0, 1);
1881 /* once for the root ptr */
1882 free_extent_buffer_stale(mid);
1883 return 0;
1884 }
1885 if (btrfs_header_nritems(mid) >
1886 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
1887 return 0;
1888
1889 left = btrfs_read_node_slot(parent, pslot - 1);
1890 if (IS_ERR(left))
1891 left = NULL;
1892
1893 if (left) {
1894 btrfs_tree_lock(left);
1895 btrfs_set_lock_blocking_write(left);
1896 wret = btrfs_cow_block(trans, root, left,
1897 parent, pslot - 1, &left);
1898 if (wret) {
1899 ret = wret;
1900 goto enospc;
1901 }
1902 }
1903
1904 right = btrfs_read_node_slot(parent, pslot + 1);
1905 if (IS_ERR(right))
1906 right = NULL;
1907
1908 if (right) {
1909 btrfs_tree_lock(right);
1910 btrfs_set_lock_blocking_write(right);
1911 wret = btrfs_cow_block(trans, root, right,
1912 parent, pslot + 1, &right);
1913 if (wret) {
1914 ret = wret;
1915 goto enospc;
1916 }
1917 }
1918
1919 /* first, try to make some room in the middle buffer */
1920 if (left) {
1921 orig_slot += btrfs_header_nritems(left);
1922 wret = push_node_left(trans, left, mid, 1);
1923 if (wret < 0)
1924 ret = wret;
1925 }
1926
1927 /*
1928 * then try to empty the right most buffer into the middle
1929 */
1930 if (right) {
1931 wret = push_node_left(trans, mid, right, 1);
1932 if (wret < 0 && wret != -ENOSPC)
1933 ret = wret;
1934 if (btrfs_header_nritems(right) == 0) {
1935 btrfs_clean_tree_block(right);
1936 btrfs_tree_unlock(right);
1937 del_ptr(root, path, level + 1, pslot + 1);
1938 root_sub_used(root, right->len);
1939 btrfs_free_tree_block(trans, root, right, 0, 1);
1940 free_extent_buffer_stale(right);
1941 right = NULL;
1942 } else {
1943 struct btrfs_disk_key right_key;
1944 btrfs_node_key(right, &right_key, 0);
1945 ret = tree_mod_log_insert_key(parent, pslot + 1,
1946 MOD_LOG_KEY_REPLACE, GFP_NOFS);
1947 BUG_ON(ret < 0);
1948 btrfs_set_node_key(parent, &right_key, pslot + 1);
1949 btrfs_mark_buffer_dirty(parent);
1950 }
1951 }
1952 if (btrfs_header_nritems(mid) == 1) {
1953 /*
1954 * we're not allowed to leave a node with one item in the
1955 * tree during a delete. A deletion from lower in the tree
1956 * could try to delete the only pointer in this node.
1957 * So, pull some keys from the left.
1958 * There has to be a left pointer at this point because
1959 * otherwise we would have pulled some pointers from the
1960 * right
1961 */
1962 if (!left) {
1963 ret = -EROFS;
1964 btrfs_handle_fs_error(fs_info, ret, NULL);
1965 goto enospc;
1966 }
1967 wret = balance_node_right(trans, mid, left);
1968 if (wret < 0) {
1969 ret = wret;
1970 goto enospc;
1971 }
1972 if (wret == 1) {
1973 wret = push_node_left(trans, left, mid, 1);
1974 if (wret < 0)
1975 ret = wret;
1976 }
1977 BUG_ON(wret == 1);
1978 }
1979 if (btrfs_header_nritems(mid) == 0) {
1980 btrfs_clean_tree_block(mid);
1981 btrfs_tree_unlock(mid);
1982 del_ptr(root, path, level + 1, pslot);
1983 root_sub_used(root, mid->len);
1984 btrfs_free_tree_block(trans, root, mid, 0, 1);
1985 free_extent_buffer_stale(mid);
1986 mid = NULL;
1987 } else {
1988 /* update the parent key to reflect our changes */
1989 struct btrfs_disk_key mid_key;
1990 btrfs_node_key(mid, &mid_key, 0);
1991 ret = tree_mod_log_insert_key(parent, pslot,
1992 MOD_LOG_KEY_REPLACE, GFP_NOFS);
1993 BUG_ON(ret < 0);
1994 btrfs_set_node_key(parent, &mid_key, pslot);
1995 btrfs_mark_buffer_dirty(parent);
1996 }
1997
1998 /* update the path */
1999 if (left) {
2000 if (btrfs_header_nritems(left) > orig_slot) {
2001 atomic_inc(&left->refs);
2002 /* left was locked after cow */
2003 path->nodes[level] = left;
2004 path->slots[level + 1] -= 1;
2005 path->slots[level] = orig_slot;
2006 if (mid) {
2007 btrfs_tree_unlock(mid);
2008 free_extent_buffer(mid);
2009 }
2010 } else {
2011 orig_slot -= btrfs_header_nritems(left);
2012 path->slots[level] = orig_slot;
2013 }
2014 }
2015 /* double check we haven't messed things up */
2016 if (orig_ptr !=
2017 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
2018 BUG();
2019enospc:
2020 if (right) {
2021 btrfs_tree_unlock(right);
2022 free_extent_buffer(right);
2023 }
2024 if (left) {
2025 if (path->nodes[level] != left)
2026 btrfs_tree_unlock(left);
2027 free_extent_buffer(left);
2028 }
2029 return ret;
2030}
2031
2032/* Node balancing for insertion. Here we only split or push nodes around
2033 * when they are completely full. This is also done top down, so we
2034 * have to be pessimistic.
2035 */
2036static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
2037 struct btrfs_root *root,
2038 struct btrfs_path *path, int level)
2039{
2040 struct btrfs_fs_info *fs_info = root->fs_info;
2041 struct extent_buffer *right = NULL;
2042 struct extent_buffer *mid;
2043 struct extent_buffer *left = NULL;
2044 struct extent_buffer *parent = NULL;
2045 int ret = 0;
2046 int wret;
2047 int pslot;
2048 int orig_slot = path->slots[level];
2049
2050 if (level == 0)
2051 return 1;
2052
2053 mid = path->nodes[level];
2054 WARN_ON(btrfs_header_generation(mid) != trans->transid);
2055
2056 if (level < BTRFS_MAX_LEVEL - 1) {
2057 parent = path->nodes[level + 1];
2058 pslot = path->slots[level + 1];
2059 }
2060
2061 if (!parent)
2062 return 1;
2063
2064 left = btrfs_read_node_slot(parent, pslot - 1);
2065 if (IS_ERR(left))
2066 left = NULL;
2067
2068 /* first, try to make some room in the middle buffer */
2069 if (left) {
2070 u32 left_nr;
2071
2072 btrfs_tree_lock(left);
2073 btrfs_set_lock_blocking_write(left);
2074
2075 left_nr = btrfs_header_nritems(left);
2076 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2077 wret = 1;
2078 } else {
2079 ret = btrfs_cow_block(trans, root, left, parent,
2080 pslot - 1, &left);
2081 if (ret)
2082 wret = 1;
2083 else {
2084 wret = push_node_left(trans, left, mid, 0);
2085 }
2086 }
2087 if (wret < 0)
2088 ret = wret;
2089 if (wret == 0) {
2090 struct btrfs_disk_key disk_key;
2091 orig_slot += left_nr;
2092 btrfs_node_key(mid, &disk_key, 0);
2093 ret = tree_mod_log_insert_key(parent, pslot,
2094 MOD_LOG_KEY_REPLACE, GFP_NOFS);
2095 BUG_ON(ret < 0);
2096 btrfs_set_node_key(parent, &disk_key, pslot);
2097 btrfs_mark_buffer_dirty(parent);
2098 if (btrfs_header_nritems(left) > orig_slot) {
2099 path->nodes[level] = left;
2100 path->slots[level + 1] -= 1;
2101 path->slots[level] = orig_slot;
2102 btrfs_tree_unlock(mid);
2103 free_extent_buffer(mid);
2104 } else {
2105 orig_slot -=
2106 btrfs_header_nritems(left);
2107 path->slots[level] = orig_slot;
2108 btrfs_tree_unlock(left);
2109 free_extent_buffer(left);
2110 }
2111 return 0;
2112 }
2113 btrfs_tree_unlock(left);
2114 free_extent_buffer(left);
2115 }
2116 right = btrfs_read_node_slot(parent, pslot + 1);
2117 if (IS_ERR(right))
2118 right = NULL;
2119
2120 /*
2121 * then try to empty the right most buffer into the middle
2122 */
2123 if (right) {
2124 u32 right_nr;
2125
2126 btrfs_tree_lock(right);
2127 btrfs_set_lock_blocking_write(right);
2128
2129 right_nr = btrfs_header_nritems(right);
2130 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2131 wret = 1;
2132 } else {
2133 ret = btrfs_cow_block(trans, root, right,
2134 parent, pslot + 1,
2135 &right);
2136 if (ret)
2137 wret = 1;
2138 else {
2139 wret = balance_node_right(trans, right, mid);
2140 }
2141 }
2142 if (wret < 0)
2143 ret = wret;
2144 if (wret == 0) {
2145 struct btrfs_disk_key disk_key;
2146
2147 btrfs_node_key(right, &disk_key, 0);
2148 ret = tree_mod_log_insert_key(parent, pslot + 1,
2149 MOD_LOG_KEY_REPLACE, GFP_NOFS);
2150 BUG_ON(ret < 0);
2151 btrfs_set_node_key(parent, &disk_key, pslot + 1);
2152 btrfs_mark_buffer_dirty(parent);
2153
2154 if (btrfs_header_nritems(mid) <= orig_slot) {
2155 path->nodes[level] = right;
2156 path->slots[level + 1] += 1;
2157 path->slots[level] = orig_slot -
2158 btrfs_header_nritems(mid);
2159 btrfs_tree_unlock(mid);
2160 free_extent_buffer(mid);
2161 } else {
2162 btrfs_tree_unlock(right);
2163 free_extent_buffer(right);
2164 }
2165 return 0;
2166 }
2167 btrfs_tree_unlock(right);
2168 free_extent_buffer(right);
2169 }
2170 return 1;
2171}
2172
2173/*
2174 * readahead one full node of leaves, finding things that are close
2175 * to the block in 'slot', and triggering ra on them.
2176 */
2177static void reada_for_search(struct btrfs_fs_info *fs_info,
2178 struct btrfs_path *path,
2179 int level, int slot, u64 objectid)
2180{
2181 struct extent_buffer *node;
2182 struct btrfs_disk_key disk_key;
2183 u32 nritems;
2184 u64 search;
2185 u64 target;
2186 u64 nread = 0;
2187 struct extent_buffer *eb;
2188 u32 nr;
2189 u32 blocksize;
2190 u32 nscan = 0;
2191
2192 if (level != 1)
2193 return;
2194
2195 if (!path->nodes[level])
2196 return;
2197
2198 node = path->nodes[level];
2199
2200 search = btrfs_node_blockptr(node, slot);
2201 blocksize = fs_info->nodesize;
2202 eb = find_extent_buffer(fs_info, search);
2203 if (eb) {
2204 free_extent_buffer(eb);
2205 return;
2206 }
2207
2208 target = search;
2209
2210 nritems = btrfs_header_nritems(node);
2211 nr = slot;
2212
2213 while (1) {
2214 if (path->reada == READA_BACK) {
2215 if (nr == 0)
2216 break;
2217 nr--;
2218 } else if (path->reada == READA_FORWARD) {
2219 nr++;
2220 if (nr >= nritems)
2221 break;
2222 }
2223 if (path->reada == READA_BACK && objectid) {
2224 btrfs_node_key(node, &disk_key, nr);
2225 if (btrfs_disk_key_objectid(&disk_key) != objectid)
2226 break;
2227 }
2228 search = btrfs_node_blockptr(node, nr);
2229 if ((search <= target && target - search <= 65536) ||
2230 (search > target && search - target <= 65536)) {
2231 readahead_tree_block(fs_info, search);
2232 nread += blocksize;
2233 }
2234 nscan++;
2235 if ((nread > 65536 || nscan > 32))
2236 break;
2237 }
2238}
2239
2240static noinline void reada_for_balance(struct btrfs_fs_info *fs_info,
2241 struct btrfs_path *path, int level)
2242{
2243 int slot;
2244 int nritems;
2245 struct extent_buffer *parent;
2246 struct extent_buffer *eb;
2247 u64 gen;
2248 u64 block1 = 0;
2249 u64 block2 = 0;
2250
2251 parent = path->nodes[level + 1];
2252 if (!parent)
2253 return;
2254
2255 nritems = btrfs_header_nritems(parent);
2256 slot = path->slots[level + 1];
2257
2258 if (slot > 0) {
2259 block1 = btrfs_node_blockptr(parent, slot - 1);
2260 gen = btrfs_node_ptr_generation(parent, slot - 1);
2261 eb = find_extent_buffer(fs_info, block1);
2262 /*
2263 * if we get -eagain from btrfs_buffer_uptodate, we
2264 * don't want to return eagain here. That will loop
2265 * forever
2266 */
2267 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2268 block1 = 0;
2269 free_extent_buffer(eb);
2270 }
2271 if (slot + 1 < nritems) {
2272 block2 = btrfs_node_blockptr(parent, slot + 1);
2273 gen = btrfs_node_ptr_generation(parent, slot + 1);
2274 eb = find_extent_buffer(fs_info, block2);
2275 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2276 block2 = 0;
2277 free_extent_buffer(eb);
2278 }
2279
2280 if (block1)
2281 readahead_tree_block(fs_info, block1);
2282 if (block2)
2283 readahead_tree_block(fs_info, block2);
2284}
2285
2286
2287/*
2288 * when we walk down the tree, it is usually safe to unlock the higher layers
2289 * in the tree. The exceptions are when our path goes through slot 0, because
2290 * operations on the tree might require changing key pointers higher up in the
2291 * tree.
2292 *
2293 * callers might also have set path->keep_locks, which tells this code to keep
2294 * the lock if the path points to the last slot in the block. This is part of
2295 * walking through the tree, and selecting the next slot in the higher block.
2296 *
2297 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
2298 * if lowest_unlock is 1, level 0 won't be unlocked
2299 */
2300static noinline void unlock_up(struct btrfs_path *path, int level,
2301 int lowest_unlock, int min_write_lock_level,
2302 int *write_lock_level)
2303{
2304 int i;
2305 int skip_level = level;
2306 int no_skips = 0;
2307 struct extent_buffer *t;
2308
2309 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2310 if (!path->nodes[i])
2311 break;
2312 if (!path->locks[i])
2313 break;
2314 if (!no_skips && path->slots[i] == 0) {
2315 skip_level = i + 1;
2316 continue;
2317 }
2318 if (!no_skips && path->keep_locks) {
2319 u32 nritems;
2320 t = path->nodes[i];
2321 nritems = btrfs_header_nritems(t);
2322 if (nritems < 1 || path->slots[i] >= nritems - 1) {
2323 skip_level = i + 1;
2324 continue;
2325 }
2326 }
2327 if (skip_level < i && i >= lowest_unlock)
2328 no_skips = 1;
2329
2330 t = path->nodes[i];
2331 if (i >= lowest_unlock && i > skip_level) {
2332 btrfs_tree_unlock_rw(t, path->locks[i]);
2333 path->locks[i] = 0;
2334 if (write_lock_level &&
2335 i > min_write_lock_level &&
2336 i <= *write_lock_level) {
2337 *write_lock_level = i - 1;
2338 }
2339 }
2340 }
2341}
2342
2343/*
2344 * helper function for btrfs_search_slot. The goal is to find a block
2345 * in cache without setting the path to blocking. If we find the block
2346 * we return zero and the path is unchanged.
2347 *
2348 * If we can't find the block, we set the path blocking and do some
2349 * reada. -EAGAIN is returned and the search must be repeated.
2350 */
2351static int
2352read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
2353 struct extent_buffer **eb_ret, int level, int slot,
2354 const struct btrfs_key *key)
2355{
2356 struct btrfs_fs_info *fs_info = root->fs_info;
2357 u64 blocknr;
2358 u64 gen;
2359 struct extent_buffer *tmp;
2360 struct btrfs_key first_key;
2361 int ret;
2362 int parent_level;
2363
2364 blocknr = btrfs_node_blockptr(*eb_ret, slot);
2365 gen = btrfs_node_ptr_generation(*eb_ret, slot);
2366 parent_level = btrfs_header_level(*eb_ret);
2367 btrfs_node_key_to_cpu(*eb_ret, &first_key, slot);
2368
2369 tmp = find_extent_buffer(fs_info, blocknr);
2370 if (tmp) {
2371 /* first we do an atomic uptodate check */
2372 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2373 /*
2374 * Do extra check for first_key, eb can be stale due to
2375 * being cached, read from scrub, or have multiple
2376 * parents (shared tree blocks).
2377 */
2378 if (btrfs_verify_level_key(tmp,
2379 parent_level - 1, &first_key, gen)) {
2380 free_extent_buffer(tmp);
2381 return -EUCLEAN;
2382 }
2383 *eb_ret = tmp;
2384 return 0;
2385 }
2386
2387 /* the pages were up to date, but we failed
2388 * the generation number check. Do a full
2389 * read for the generation number that is correct.
2390 * We must do this without dropping locks so
2391 * we can trust our generation number
2392 */
2393 btrfs_set_path_blocking(p);
2394
2395 /* now we're allowed to do a blocking uptodate check */
2396 ret = btrfs_read_buffer(tmp, gen, parent_level - 1, &first_key);
2397 if (!ret) {
2398 *eb_ret = tmp;
2399 return 0;
2400 }
2401 free_extent_buffer(tmp);
2402 btrfs_release_path(p);
2403 return -EIO;
2404 }
2405
2406 /*
2407 * reduce lock contention at high levels
2408 * of the btree by dropping locks before
2409 * we read. Don't release the lock on the current
2410 * level because we need to walk this node to figure
2411 * out which blocks to read.
2412 */
2413 btrfs_unlock_up_safe(p, level + 1);
2414 btrfs_set_path_blocking(p);
2415
2416 if (p->reada != READA_NONE)
2417 reada_for_search(fs_info, p, level, slot, key->objectid);
2418
2419 ret = -EAGAIN;
2420 tmp = read_tree_block(fs_info, blocknr, gen, parent_level - 1,
2421 &first_key);
2422 if (!IS_ERR(tmp)) {
2423 /*
2424 * If the read above didn't mark this buffer up to date,
2425 * it will never end up being up to date. Set ret to EIO now
2426 * and give up so that our caller doesn't loop forever
2427 * on our EAGAINs.
2428 */
2429 if (!extent_buffer_uptodate(tmp))
2430 ret = -EIO;
2431 free_extent_buffer(tmp);
2432 } else {
2433 ret = PTR_ERR(tmp);
2434 }
2435
2436 btrfs_release_path(p);
2437 return ret;
2438}
2439
2440/*
2441 * helper function for btrfs_search_slot. This does all of the checks
2442 * for node-level blocks and does any balancing required based on
2443 * the ins_len.
2444 *
2445 * If no extra work was required, zero is returned. If we had to
2446 * drop the path, -EAGAIN is returned and btrfs_search_slot must
2447 * start over
2448 */
2449static int
2450setup_nodes_for_search(struct btrfs_trans_handle *trans,
2451 struct btrfs_root *root, struct btrfs_path *p,
2452 struct extent_buffer *b, int level, int ins_len,
2453 int *write_lock_level)
2454{
2455 struct btrfs_fs_info *fs_info = root->fs_info;
2456 int ret;
2457
2458 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2459 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
2460 int sret;
2461
2462 if (*write_lock_level < level + 1) {
2463 *write_lock_level = level + 1;
2464 btrfs_release_path(p);
2465 goto again;
2466 }
2467
2468 btrfs_set_path_blocking(p);
2469 reada_for_balance(fs_info, p, level);
2470 sret = split_node(trans, root, p, level);
2471
2472 BUG_ON(sret > 0);
2473 if (sret) {
2474 ret = sret;
2475 goto done;
2476 }
2477 b = p->nodes[level];
2478 } else if (ins_len < 0 && btrfs_header_nritems(b) <
2479 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
2480 int sret;
2481
2482 if (*write_lock_level < level + 1) {
2483 *write_lock_level = level + 1;
2484 btrfs_release_path(p);
2485 goto again;
2486 }
2487
2488 btrfs_set_path_blocking(p);
2489 reada_for_balance(fs_info, p, level);
2490 sret = balance_level(trans, root, p, level);
2491
2492 if (sret) {
2493 ret = sret;
2494 goto done;
2495 }
2496 b = p->nodes[level];
2497 if (!b) {
2498 btrfs_release_path(p);
2499 goto again;
2500 }
2501 BUG_ON(btrfs_header_nritems(b) == 1);
2502 }
2503 return 0;
2504
2505again:
2506 ret = -EAGAIN;
2507done:
2508 return ret;
2509}
2510
2511int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
2512 u64 iobjectid, u64 ioff, u8 key_type,
2513 struct btrfs_key *found_key)
2514{
2515 int ret;
2516 struct btrfs_key key;
2517 struct extent_buffer *eb;
2518
2519 ASSERT(path);
2520 ASSERT(found_key);
2521
2522 key.type = key_type;
2523 key.objectid = iobjectid;
2524 key.offset = ioff;
2525
2526 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
2527 if (ret < 0)
2528 return ret;
2529
2530 eb = path->nodes[0];
2531 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
2532 ret = btrfs_next_leaf(fs_root, path);
2533 if (ret)
2534 return ret;
2535 eb = path->nodes[0];
2536 }
2537
2538 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
2539 if (found_key->type != key.type ||
2540 found_key->objectid != key.objectid)
2541 return 1;
2542
2543 return 0;
2544}
2545
2546static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
2547 struct btrfs_path *p,
2548 int write_lock_level)
2549{
2550 struct btrfs_fs_info *fs_info = root->fs_info;
2551 struct extent_buffer *b;
2552 int root_lock;
2553 int level = 0;
2554
2555 /* We try very hard to do read locks on the root */
2556 root_lock = BTRFS_READ_LOCK;
2557
2558 if (p->search_commit_root) {
2559 /*
2560 * The commit roots are read only so we always do read locks,
2561 * and we always must hold the commit_root_sem when doing
2562 * searches on them, the only exception is send where we don't
2563 * want to block transaction commits for a long time, so
2564 * we need to clone the commit root in order to avoid races
2565 * with transaction commits that create a snapshot of one of
2566 * the roots used by a send operation.
2567 */
2568 if (p->need_commit_sem) {
2569 down_read(&fs_info->commit_root_sem);
2570 b = btrfs_clone_extent_buffer(root->commit_root);
2571 up_read(&fs_info->commit_root_sem);
2572 if (!b)
2573 return ERR_PTR(-ENOMEM);
2574
2575 } else {
2576 b = root->commit_root;
2577 atomic_inc(&b->refs);
2578 }
2579 level = btrfs_header_level(b);
2580 /*
2581 * Ensure that all callers have set skip_locking when
2582 * p->search_commit_root = 1.
2583 */
2584 ASSERT(p->skip_locking == 1);
2585
2586 goto out;
2587 }
2588
2589 if (p->skip_locking) {
2590 b = btrfs_root_node(root);
2591 level = btrfs_header_level(b);
2592 goto out;
2593 }
2594
2595 /*
2596 * If the level is set to maximum, we can skip trying to get the read
2597 * lock.
2598 */
2599 if (write_lock_level < BTRFS_MAX_LEVEL) {
2600 /*
2601 * We don't know the level of the root node until we actually
2602 * have it read locked
2603 */
2604 b = btrfs_read_lock_root_node(root);
2605 level = btrfs_header_level(b);
2606 if (level > write_lock_level)
2607 goto out;
2608
2609 /* Whoops, must trade for write lock */
2610 btrfs_tree_read_unlock(b);
2611 free_extent_buffer(b);
2612 }
2613
2614 b = btrfs_lock_root_node(root);
2615 root_lock = BTRFS_WRITE_LOCK;
2616
2617 /* The level might have changed, check again */
2618 level = btrfs_header_level(b);
2619
2620out:
2621 p->nodes[level] = b;
2622 if (!p->skip_locking)
2623 p->locks[level] = root_lock;
2624 /*
2625 * Callers are responsible for dropping b's references.
2626 */
2627 return b;
2628}
2629
2630
2631/*
2632 * btrfs_search_slot - look for a key in a tree and perform necessary
2633 * modifications to preserve tree invariants.
2634 *
2635 * @trans: Handle of transaction, used when modifying the tree
2636 * @p: Holds all btree nodes along the search path
2637 * @root: The root node of the tree
2638 * @key: The key we are looking for
2639 * @ins_len: Indicates purpose of search, for inserts it is 1, for
2640 * deletions it's -1. 0 for plain searches
2641 * @cow: boolean should CoW operations be performed. Must always be 1
2642 * when modifying the tree.
2643 *
2644 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
2645 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
2646 *
2647 * If @key is found, 0 is returned and you can find the item in the leaf level
2648 * of the path (level 0)
2649 *
2650 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
2651 * points to the slot where it should be inserted
2652 *
2653 * If an error is encountered while searching the tree a negative error number
2654 * is returned
2655 */
2656int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2657 const struct btrfs_key *key, struct btrfs_path *p,
2658 int ins_len, int cow)
2659{
2660 struct extent_buffer *b;
2661 int slot;
2662 int ret;
2663 int err;
2664 int level;
2665 int lowest_unlock = 1;
2666 /* everything at write_lock_level or lower must be write locked */
2667 int write_lock_level = 0;
2668 u8 lowest_level = 0;
2669 int min_write_lock_level;
2670 int prev_cmp;
2671
2672 lowest_level = p->lowest_level;
2673 WARN_ON(lowest_level && ins_len > 0);
2674 WARN_ON(p->nodes[0] != NULL);
2675 BUG_ON(!cow && ins_len);
2676
2677 if (ins_len < 0) {
2678 lowest_unlock = 2;
2679
2680 /* when we are removing items, we might have to go up to level
2681 * two as we update tree pointers Make sure we keep write
2682 * for those levels as well
2683 */
2684 write_lock_level = 2;
2685 } else if (ins_len > 0) {
2686 /*
2687 * for inserting items, make sure we have a write lock on
2688 * level 1 so we can update keys
2689 */
2690 write_lock_level = 1;
2691 }
2692
2693 if (!cow)
2694 write_lock_level = -1;
2695
2696 if (cow && (p->keep_locks || p->lowest_level))
2697 write_lock_level = BTRFS_MAX_LEVEL;
2698
2699 min_write_lock_level = write_lock_level;
2700
2701again:
2702 prev_cmp = -1;
2703 b = btrfs_search_slot_get_root(root, p, write_lock_level);
2704 if (IS_ERR(b)) {
2705 ret = PTR_ERR(b);
2706 goto done;
2707 }
2708
2709 while (b) {
2710 int dec = 0;
2711
2712 level = btrfs_header_level(b);
2713
2714 if (cow) {
2715 bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2716
2717 /*
2718 * if we don't really need to cow this block
2719 * then we don't want to set the path blocking,
2720 * so we test it here
2721 */
2722 if (!should_cow_block(trans, root, b)) {
2723 trans->dirty = true;
2724 goto cow_done;
2725 }
2726
2727 /*
2728 * must have write locks on this node and the
2729 * parent
2730 */
2731 if (level > write_lock_level ||
2732 (level + 1 > write_lock_level &&
2733 level + 1 < BTRFS_MAX_LEVEL &&
2734 p->nodes[level + 1])) {
2735 write_lock_level = level + 1;
2736 btrfs_release_path(p);
2737 goto again;
2738 }
2739
2740 btrfs_set_path_blocking(p);
2741 if (last_level)
2742 err = btrfs_cow_block(trans, root, b, NULL, 0,
2743 &b);
2744 else
2745 err = btrfs_cow_block(trans, root, b,
2746 p->nodes[level + 1],
2747 p->slots[level + 1], &b);
2748 if (err) {
2749 ret = err;
2750 goto done;
2751 }
2752 }
2753cow_done:
2754 p->nodes[level] = b;
2755 /*
2756 * Leave path with blocking locks to avoid massive
2757 * lock context switch, this is made on purpose.
2758 */
2759
2760 /*
2761 * we have a lock on b and as long as we aren't changing
2762 * the tree, there is no way to for the items in b to change.
2763 * It is safe to drop the lock on our parent before we
2764 * go through the expensive btree search on b.
2765 *
2766 * If we're inserting or deleting (ins_len != 0), then we might
2767 * be changing slot zero, which may require changing the parent.
2768 * So, we can't drop the lock until after we know which slot
2769 * we're operating on.
2770 */
2771 if (!ins_len && !p->keep_locks) {
2772 int u = level + 1;
2773
2774 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2775 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2776 p->locks[u] = 0;
2777 }
2778 }
2779
2780 /*
2781 * If btrfs_bin_search returns an exact match (prev_cmp == 0)
2782 * we can safely assume the target key will always be in slot 0
2783 * on lower levels due to the invariants BTRFS' btree provides,
2784 * namely that a btrfs_key_ptr entry always points to the
2785 * lowest key in the child node, thus we can skip searching
2786 * lower levels
2787 */
2788 if (prev_cmp == 0) {
2789 slot = 0;
2790 ret = 0;
2791 } else {
2792 ret = btrfs_bin_search(b, key, &slot);
2793 prev_cmp = ret;
2794 if (ret < 0)
2795 goto done;
2796 }
2797
2798 if (level == 0) {
2799 p->slots[level] = slot;
2800 if (ins_len > 0 &&
2801 btrfs_leaf_free_space(b) < ins_len) {
2802 if (write_lock_level < 1) {
2803 write_lock_level = 1;
2804 btrfs_release_path(p);
2805 goto again;
2806 }
2807
2808 btrfs_set_path_blocking(p);
2809 err = split_leaf(trans, root, key,
2810 p, ins_len, ret == 0);
2811
2812 BUG_ON(err > 0);
2813 if (err) {
2814 ret = err;
2815 goto done;
2816 }
2817 }
2818 if (!p->search_for_split)
2819 unlock_up(p, level, lowest_unlock,
2820 min_write_lock_level, NULL);
2821 goto done;
2822 }
2823 if (ret && slot > 0) {
2824 dec = 1;
2825 slot--;
2826 }
2827 p->slots[level] = slot;
2828 err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
2829 &write_lock_level);
2830 if (err == -EAGAIN)
2831 goto again;
2832 if (err) {
2833 ret = err;
2834 goto done;
2835 }
2836 b = p->nodes[level];
2837 slot = p->slots[level];
2838
2839 /*
2840 * Slot 0 is special, if we change the key we have to update
2841 * the parent pointer which means we must have a write lock on
2842 * the parent
2843 */
2844 if (slot == 0 && ins_len && write_lock_level < level + 1) {
2845 write_lock_level = level + 1;
2846 btrfs_release_path(p);
2847 goto again;
2848 }
2849
2850 unlock_up(p, level, lowest_unlock, min_write_lock_level,
2851 &write_lock_level);
2852
2853 if (level == lowest_level) {
2854 if (dec)
2855 p->slots[level]++;
2856 goto done;
2857 }
2858
2859 err = read_block_for_search(root, p, &b, level, slot, key);
2860 if (err == -EAGAIN)
2861 goto again;
2862 if (err) {
2863 ret = err;
2864 goto done;
2865 }
2866
2867 if (!p->skip_locking) {
2868 level = btrfs_header_level(b);
2869 if (level <= write_lock_level) {
2870 if (!btrfs_try_tree_write_lock(b)) {
2871 btrfs_set_path_blocking(p);
2872 btrfs_tree_lock(b);
2873 }
2874 p->locks[level] = BTRFS_WRITE_LOCK;
2875 } else {
2876 if (!btrfs_tree_read_lock_atomic(b)) {
2877 btrfs_set_path_blocking(p);
2878 btrfs_tree_read_lock(b);
2879 }
2880 p->locks[level] = BTRFS_READ_LOCK;
2881 }
2882 p->nodes[level] = b;
2883 }
2884 }
2885 ret = 1;
2886done:
2887 /*
2888 * we don't really know what they plan on doing with the path
2889 * from here on, so for now just mark it as blocking
2890 */
2891 if (!p->leave_spinning)
2892 btrfs_set_path_blocking(p);
2893 if (ret < 0 && !p->skip_release_on_error)
2894 btrfs_release_path(p);
2895 return ret;
2896}
2897
2898/*
2899 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2900 * current state of the tree together with the operations recorded in the tree
2901 * modification log to search for the key in a previous version of this tree, as
2902 * denoted by the time_seq parameter.
2903 *
2904 * Naturally, there is no support for insert, delete or cow operations.
2905 *
2906 * The resulting path and return value will be set up as if we called
2907 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2908 */
2909int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2910 struct btrfs_path *p, u64 time_seq)
2911{
2912 struct btrfs_fs_info *fs_info = root->fs_info;
2913 struct extent_buffer *b;
2914 int slot;
2915 int ret;
2916 int err;
2917 int level;
2918 int lowest_unlock = 1;
2919 u8 lowest_level = 0;
2920
2921 lowest_level = p->lowest_level;
2922 WARN_ON(p->nodes[0] != NULL);
2923
2924 if (p->search_commit_root) {
2925 BUG_ON(time_seq);
2926 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2927 }
2928
2929again:
2930 b = get_old_root(root, time_seq);
2931 if (!b) {
2932 ret = -EIO;
2933 goto done;
2934 }
2935 level = btrfs_header_level(b);
2936 p->locks[level] = BTRFS_READ_LOCK;
2937
2938 while (b) {
2939 int dec = 0;
2940
2941 level = btrfs_header_level(b);
2942 p->nodes[level] = b;
2943
2944 /*
2945 * we have a lock on b and as long as we aren't changing
2946 * the tree, there is no way to for the items in b to change.
2947 * It is safe to drop the lock on our parent before we
2948 * go through the expensive btree search on b.
2949 */
2950 btrfs_unlock_up_safe(p, level + 1);
2951
2952 ret = btrfs_bin_search(b, key, &slot);
2953 if (ret < 0)
2954 goto done;
2955
2956 if (level == 0) {
2957 p->slots[level] = slot;
2958 unlock_up(p, level, lowest_unlock, 0, NULL);
2959 goto done;
2960 }
2961
2962 if (ret && slot > 0) {
2963 dec = 1;
2964 slot--;
2965 }
2966 p->slots[level] = slot;
2967 unlock_up(p, level, lowest_unlock, 0, NULL);
2968
2969 if (level == lowest_level) {
2970 if (dec)
2971 p->slots[level]++;
2972 goto done;
2973 }
2974
2975 err = read_block_for_search(root, p, &b, level, slot, key);
2976 if (err == -EAGAIN)
2977 goto again;
2978 if (err) {
2979 ret = err;
2980 goto done;
2981 }
2982
2983 level = btrfs_header_level(b);
2984 if (!btrfs_tree_read_lock_atomic(b)) {
2985 btrfs_set_path_blocking(p);
2986 btrfs_tree_read_lock(b);
2987 }
2988 b = tree_mod_log_rewind(fs_info, p, b, time_seq);
2989 if (!b) {
2990 ret = -ENOMEM;
2991 goto done;
2992 }
2993 p->locks[level] = BTRFS_READ_LOCK;
2994 p->nodes[level] = b;
2995 }
2996 ret = 1;
2997done:
2998 if (!p->leave_spinning)
2999 btrfs_set_path_blocking(p);
3000 if (ret < 0)
3001 btrfs_release_path(p);
3002
3003 return ret;
3004}
3005
3006/*
3007 * helper to use instead of search slot if no exact match is needed but
3008 * instead the next or previous item should be returned.
3009 * When find_higher is true, the next higher item is returned, the next lower
3010 * otherwise.
3011 * When return_any and find_higher are both true, and no higher item is found,
3012 * return the next lower instead.
3013 * When return_any is true and find_higher is false, and no lower item is found,
3014 * return the next higher instead.
3015 * It returns 0 if any item is found, 1 if none is found (tree empty), and
3016 * < 0 on error
3017 */
3018int btrfs_search_slot_for_read(struct btrfs_root *root,
3019 const struct btrfs_key *key,
3020 struct btrfs_path *p, int find_higher,
3021 int return_any)
3022{
3023 int ret;
3024 struct extent_buffer *leaf;
3025
3026again:
3027 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
3028 if (ret <= 0)
3029 return ret;
3030 /*
3031 * a return value of 1 means the path is at the position where the
3032 * item should be inserted. Normally this is the next bigger item,
3033 * but in case the previous item is the last in a leaf, path points
3034 * to the first free slot in the previous leaf, i.e. at an invalid
3035 * item.
3036 */
3037 leaf = p->nodes[0];
3038
3039 if (find_higher) {
3040 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
3041 ret = btrfs_next_leaf(root, p);
3042 if (ret <= 0)
3043 return ret;
3044 if (!return_any)
3045 return 1;
3046 /*
3047 * no higher item found, return the next
3048 * lower instead
3049 */
3050 return_any = 0;
3051 find_higher = 0;
3052 btrfs_release_path(p);
3053 goto again;
3054 }
3055 } else {
3056 if (p->slots[0] == 0) {
3057 ret = btrfs_prev_leaf(root, p);
3058 if (ret < 0)
3059 return ret;
3060 if (!ret) {
3061 leaf = p->nodes[0];
3062 if (p->slots[0] == btrfs_header_nritems(leaf))
3063 p->slots[0]--;
3064 return 0;
3065 }
3066 if (!return_any)
3067 return 1;
3068 /*
3069 * no lower item found, return the next
3070 * higher instead
3071 */
3072 return_any = 0;
3073 find_higher = 1;
3074 btrfs_release_path(p);
3075 goto again;
3076 } else {
3077 --p->slots[0];
3078 }
3079 }
3080 return 0;
3081}
3082
3083/*
3084 * adjust the pointers going up the tree, starting at level
3085 * making sure the right key of each node is points to 'key'.
3086 * This is used after shifting pointers to the left, so it stops
3087 * fixing up pointers when a given leaf/node is not in slot 0 of the
3088 * higher levels
3089 *
3090 */
3091static void fixup_low_keys(struct btrfs_path *path,
3092 struct btrfs_disk_key *key, int level)
3093{
3094 int i;
3095 struct extent_buffer *t;
3096 int ret;
3097
3098 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
3099 int tslot = path->slots[i];
3100
3101 if (!path->nodes[i])
3102 break;
3103 t = path->nodes[i];
3104 ret = tree_mod_log_insert_key(t, tslot, MOD_LOG_KEY_REPLACE,
3105 GFP_ATOMIC);
3106 BUG_ON(ret < 0);
3107 btrfs_set_node_key(t, key, tslot);
3108 btrfs_mark_buffer_dirty(path->nodes[i]);
3109 if (tslot != 0)
3110 break;
3111 }
3112}
3113
3114/*
3115 * update item key.
3116 *
3117 * This function isn't completely safe. It's the caller's responsibility
3118 * that the new key won't break the order
3119 */
3120void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
3121 struct btrfs_path *path,
3122 const struct btrfs_key *new_key)
3123{
3124 struct btrfs_disk_key disk_key;
3125 struct extent_buffer *eb;
3126 int slot;
3127
3128 eb = path->nodes[0];
3129 slot = path->slots[0];
3130 if (slot > 0) {
3131 btrfs_item_key(eb, &disk_key, slot - 1);
3132 if (unlikely(comp_keys(&disk_key, new_key) >= 0)) {
3133 btrfs_crit(fs_info,
3134 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
3135 slot, btrfs_disk_key_objectid(&disk_key),
3136 btrfs_disk_key_type(&disk_key),
3137 btrfs_disk_key_offset(&disk_key),
3138 new_key->objectid, new_key->type,
3139 new_key->offset);
3140 btrfs_print_leaf(eb);
3141 BUG();
3142 }
3143 }
3144 if (slot < btrfs_header_nritems(eb) - 1) {
3145 btrfs_item_key(eb, &disk_key, slot + 1);
3146 if (unlikely(comp_keys(&disk_key, new_key) <= 0)) {
3147 btrfs_crit(fs_info,
3148 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
3149 slot, btrfs_disk_key_objectid(&disk_key),
3150 btrfs_disk_key_type(&disk_key),
3151 btrfs_disk_key_offset(&disk_key),
3152 new_key->objectid, new_key->type,
3153 new_key->offset);
3154 btrfs_print_leaf(eb);
3155 BUG();
3156 }
3157 }
3158
3159 btrfs_cpu_key_to_disk(&disk_key, new_key);
3160 btrfs_set_item_key(eb, &disk_key, slot);
3161 btrfs_mark_buffer_dirty(eb);
3162 if (slot == 0)
3163 fixup_low_keys(path, &disk_key, 1);
3164}
3165
3166/*
3167 * try to push data from one node into the next node left in the
3168 * tree.
3169 *
3170 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
3171 * error, and > 0 if there was no room in the left hand block.
3172 */
3173static int push_node_left(struct btrfs_trans_handle *trans,
3174 struct extent_buffer *dst,
3175 struct extent_buffer *src, int empty)
3176{
3177 struct btrfs_fs_info *fs_info = trans->fs_info;
3178 int push_items = 0;
3179 int src_nritems;
3180 int dst_nritems;
3181 int ret = 0;
3182
3183 src_nritems = btrfs_header_nritems(src);
3184 dst_nritems = btrfs_header_nritems(dst);
3185 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
3186 WARN_ON(btrfs_header_generation(src) != trans->transid);
3187 WARN_ON(btrfs_header_generation(dst) != trans->transid);
3188
3189 if (!empty && src_nritems <= 8)
3190 return 1;
3191
3192 if (push_items <= 0)
3193 return 1;
3194
3195 if (empty) {
3196 push_items = min(src_nritems, push_items);
3197 if (push_items < src_nritems) {
3198 /* leave at least 8 pointers in the node if
3199 * we aren't going to empty it
3200 */
3201 if (src_nritems - push_items < 8) {
3202 if (push_items <= 8)
3203 return 1;
3204 push_items -= 8;
3205 }
3206 }
3207 } else
3208 push_items = min(src_nritems - 8, push_items);
3209
3210 ret = tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
3211 if (ret) {
3212 btrfs_abort_transaction(trans, ret);
3213 return ret;
3214 }
3215 copy_extent_buffer(dst, src,
3216 btrfs_node_key_ptr_offset(dst_nritems),
3217 btrfs_node_key_ptr_offset(0),
3218 push_items * sizeof(struct btrfs_key_ptr));
3219
3220 if (push_items < src_nritems) {
3221 /*
3222 * Don't call tree_mod_log_insert_move here, key removal was
3223 * already fully logged by tree_mod_log_eb_copy above.
3224 */
3225 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
3226 btrfs_node_key_ptr_offset(push_items),
3227 (src_nritems - push_items) *
3228 sizeof(struct btrfs_key_ptr));
3229 }
3230 btrfs_set_header_nritems(src, src_nritems - push_items);
3231 btrfs_set_header_nritems(dst, dst_nritems + push_items);
3232 btrfs_mark_buffer_dirty(src);
3233 btrfs_mark_buffer_dirty(dst);
3234
3235 return ret;
3236}
3237
3238/*
3239 * try to push data from one node into the next node right in the
3240 * tree.
3241 *
3242 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
3243 * error, and > 0 if there was no room in the right hand block.
3244 *
3245 * this will only push up to 1/2 the contents of the left node over
3246 */
3247static int balance_node_right(struct btrfs_trans_handle *trans,
3248 struct extent_buffer *dst,
3249 struct extent_buffer *src)
3250{
3251 struct btrfs_fs_info *fs_info = trans->fs_info;
3252 int push_items = 0;
3253 int max_push;
3254 int src_nritems;
3255 int dst_nritems;
3256 int ret = 0;
3257
3258 WARN_ON(btrfs_header_generation(src) != trans->transid);
3259 WARN_ON(btrfs_header_generation(dst) != trans->transid);
3260
3261 src_nritems = btrfs_header_nritems(src);
3262 dst_nritems = btrfs_header_nritems(dst);
3263 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
3264 if (push_items <= 0)
3265 return 1;
3266
3267 if (src_nritems < 4)
3268 return 1;
3269
3270 max_push = src_nritems / 2 + 1;
3271 /* don't try to empty the node */
3272 if (max_push >= src_nritems)
3273 return 1;
3274
3275 if (max_push < push_items)
3276 push_items = max_push;
3277
3278 ret = tree_mod_log_insert_move(dst, push_items, 0, dst_nritems);
3279 BUG_ON(ret < 0);
3280 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
3281 btrfs_node_key_ptr_offset(0),
3282 (dst_nritems) *
3283 sizeof(struct btrfs_key_ptr));
3284
3285 ret = tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
3286 push_items);
3287 if (ret) {
3288 btrfs_abort_transaction(trans, ret);
3289 return ret;
3290 }
3291 copy_extent_buffer(dst, src,
3292 btrfs_node_key_ptr_offset(0),
3293 btrfs_node_key_ptr_offset(src_nritems - push_items),
3294 push_items * sizeof(struct btrfs_key_ptr));
3295
3296 btrfs_set_header_nritems(src, src_nritems - push_items);
3297 btrfs_set_header_nritems(dst, dst_nritems + push_items);
3298
3299 btrfs_mark_buffer_dirty(src);
3300 btrfs_mark_buffer_dirty(dst);
3301
3302 return ret;
3303}
3304
3305/*
3306 * helper function to insert a new root level in the tree.
3307 * A new node is allocated, and a single item is inserted to
3308 * point to the existing root
3309 *
3310 * returns zero on success or < 0 on failure.
3311 */
3312static noinline int insert_new_root(struct btrfs_trans_handle *trans,
3313 struct btrfs_root *root,
3314 struct btrfs_path *path, int level)
3315{
3316 struct btrfs_fs_info *fs_info = root->fs_info;
3317 u64 lower_gen;
3318 struct extent_buffer *lower;
3319 struct extent_buffer *c;
3320 struct extent_buffer *old;
3321 struct btrfs_disk_key lower_key;
3322 int ret;
3323
3324 BUG_ON(path->nodes[level]);
3325 BUG_ON(path->nodes[level-1] != root->node);
3326
3327 lower = path->nodes[level-1];
3328 if (level == 1)
3329 btrfs_item_key(lower, &lower_key, 0);
3330 else
3331 btrfs_node_key(lower, &lower_key, 0);
3332
3333 c = alloc_tree_block_no_bg_flush(trans, root, 0, &lower_key, level,
3334 root->node->start, 0);
3335 if (IS_ERR(c))
3336 return PTR_ERR(c);
3337
3338 root_add_used(root, fs_info->nodesize);
3339
3340 btrfs_set_header_nritems(c, 1);
3341 btrfs_set_node_key(c, &lower_key, 0);
3342 btrfs_set_node_blockptr(c, 0, lower->start);
3343 lower_gen = btrfs_header_generation(lower);
3344 WARN_ON(lower_gen != trans->transid);
3345
3346 btrfs_set_node_ptr_generation(c, 0, lower_gen);
3347
3348 btrfs_mark_buffer_dirty(c);
3349
3350 old = root->node;
3351 ret = tree_mod_log_insert_root(root->node, c, 0);
3352 BUG_ON(ret < 0);
3353 rcu_assign_pointer(root->node, c);
3354
3355 /* the super has an extra ref to root->node */
3356 free_extent_buffer(old);
3357
3358 add_root_to_dirty_list(root);
3359 atomic_inc(&c->refs);
3360 path->nodes[level] = c;
3361 path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
3362 path->slots[level] = 0;
3363 return 0;
3364}
3365
3366/*
3367 * worker function to insert a single pointer in a node.
3368 * the node should have enough room for the pointer already
3369 *
3370 * slot and level indicate where you want the key to go, and
3371 * blocknr is the block the key points to.
3372 */
3373static void insert_ptr(struct btrfs_trans_handle *trans,
3374 struct btrfs_path *path,
3375 struct btrfs_disk_key *key, u64 bytenr,
3376 int slot, int level)
3377{
3378 struct extent_buffer *lower;
3379 int nritems;
3380 int ret;
3381
3382 BUG_ON(!path->nodes[level]);
3383 btrfs_assert_tree_locked(path->nodes[level]);
3384 lower = path->nodes[level];
3385 nritems = btrfs_header_nritems(lower);
3386 BUG_ON(slot > nritems);
3387 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
3388 if (slot != nritems) {
3389 if (level) {
3390 ret = tree_mod_log_insert_move(lower, slot + 1, slot,
3391 nritems - slot);
3392 BUG_ON(ret < 0);
3393 }
3394 memmove_extent_buffer(lower,
3395 btrfs_node_key_ptr_offset(slot + 1),
3396 btrfs_node_key_ptr_offset(slot),
3397 (nritems - slot) * sizeof(struct btrfs_key_ptr));
3398 }
3399 if (level) {
3400 ret = tree_mod_log_insert_key(lower, slot, MOD_LOG_KEY_ADD,
3401 GFP_NOFS);
3402 BUG_ON(ret < 0);
3403 }
3404 btrfs_set_node_key(lower, key, slot);
3405 btrfs_set_node_blockptr(lower, slot, bytenr);
3406 WARN_ON(trans->transid == 0);
3407 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3408 btrfs_set_header_nritems(lower, nritems + 1);
3409 btrfs_mark_buffer_dirty(lower);
3410}
3411
3412/*
3413 * split the node at the specified level in path in two.
3414 * The path is corrected to point to the appropriate node after the split
3415 *
3416 * Before splitting this tries to make some room in the node by pushing
3417 * left and right, if either one works, it returns right away.
3418 *
3419 * returns 0 on success and < 0 on failure
3420 */
3421static noinline int split_node(struct btrfs_trans_handle *trans,
3422 struct btrfs_root *root,
3423 struct btrfs_path *path, int level)
3424{
3425 struct btrfs_fs_info *fs_info = root->fs_info;
3426 struct extent_buffer *c;
3427 struct extent_buffer *split;
3428 struct btrfs_disk_key disk_key;
3429 int mid;
3430 int ret;
3431 u32 c_nritems;
3432
3433 c = path->nodes[level];
3434 WARN_ON(btrfs_header_generation(c) != trans->transid);
3435 if (c == root->node) {
3436 /*
3437 * trying to split the root, lets make a new one
3438 *
3439 * tree mod log: We don't log_removal old root in
3440 * insert_new_root, because that root buffer will be kept as a
3441 * normal node. We are going to log removal of half of the
3442 * elements below with tree_mod_log_eb_copy. We're holding a
3443 * tree lock on the buffer, which is why we cannot race with
3444 * other tree_mod_log users.
3445 */
3446 ret = insert_new_root(trans, root, path, level + 1);
3447 if (ret)
3448 return ret;
3449 } else {
3450 ret = push_nodes_for_insert(trans, root, path, level);
3451 c = path->nodes[level];
3452 if (!ret && btrfs_header_nritems(c) <
3453 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
3454 return 0;
3455 if (ret < 0)
3456 return ret;
3457 }
3458
3459 c_nritems = btrfs_header_nritems(c);
3460 mid = (c_nritems + 1) / 2;
3461 btrfs_node_key(c, &disk_key, mid);
3462
3463 split = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, level,
3464 c->start, 0);
3465 if (IS_ERR(split))
3466 return PTR_ERR(split);
3467
3468 root_add_used(root, fs_info->nodesize);
3469 ASSERT(btrfs_header_level(c) == level);
3470
3471 ret = tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
3472 if (ret) {
3473 btrfs_abort_transaction(trans, ret);
3474 return ret;
3475 }
3476 copy_extent_buffer(split, c,
3477 btrfs_node_key_ptr_offset(0),
3478 btrfs_node_key_ptr_offset(mid),
3479 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3480 btrfs_set_header_nritems(split, c_nritems - mid);
3481 btrfs_set_header_nritems(c, mid);
3482 ret = 0;
3483
3484 btrfs_mark_buffer_dirty(c);
3485 btrfs_mark_buffer_dirty(split);
3486
3487 insert_ptr(trans, path, &disk_key, split->start,
3488 path->slots[level + 1] + 1, level + 1);
3489
3490 if (path->slots[level] >= mid) {
3491 path->slots[level] -= mid;
3492 btrfs_tree_unlock(c);
3493 free_extent_buffer(c);
3494 path->nodes[level] = split;
3495 path->slots[level + 1] += 1;
3496 } else {
3497 btrfs_tree_unlock(split);
3498 free_extent_buffer(split);
3499 }
3500 return ret;
3501}
3502
3503/*
3504 * how many bytes are required to store the items in a leaf. start
3505 * and nr indicate which items in the leaf to check. This totals up the
3506 * space used both by the item structs and the item data
3507 */
3508static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3509{
3510 struct btrfs_item *start_item;
3511 struct btrfs_item *end_item;
3512 int data_len;
3513 int nritems = btrfs_header_nritems(l);
3514 int end = min(nritems, start + nr) - 1;
3515
3516 if (!nr)
3517 return 0;
3518 start_item = btrfs_item_nr(start);
3519 end_item = btrfs_item_nr(end);
3520 data_len = btrfs_item_offset(l, start_item) +
3521 btrfs_item_size(l, start_item);
3522 data_len = data_len - btrfs_item_offset(l, end_item);
3523 data_len += sizeof(struct btrfs_item) * nr;
3524 WARN_ON(data_len < 0);
3525 return data_len;
3526}
3527
3528/*
3529 * The space between the end of the leaf items and
3530 * the start of the leaf data. IOW, how much room
3531 * the leaf has left for both items and data
3532 */
3533noinline int btrfs_leaf_free_space(struct extent_buffer *leaf)
3534{
3535 struct btrfs_fs_info *fs_info = leaf->fs_info;
3536 int nritems = btrfs_header_nritems(leaf);
3537 int ret;
3538
3539 ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
3540 if (ret < 0) {
3541 btrfs_crit(fs_info,
3542 "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3543 ret,
3544 (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
3545 leaf_space_used(leaf, 0, nritems), nritems);
3546 }
3547 return ret;
3548}
3549
3550/*
3551 * min slot controls the lowest index we're willing to push to the
3552 * right. We'll push up to and including min_slot, but no lower
3553 */
3554static noinline int __push_leaf_right(struct btrfs_path *path,
3555 int data_size, int empty,
3556 struct extent_buffer *right,
3557 int free_space, u32 left_nritems,
3558 u32 min_slot)
3559{
3560 struct btrfs_fs_info *fs_info = right->fs_info;
3561 struct extent_buffer *left = path->nodes[0];
3562 struct extent_buffer *upper = path->nodes[1];
3563 struct btrfs_map_token token;
3564 struct btrfs_disk_key disk_key;
3565 int slot;
3566 u32 i;
3567 int push_space = 0;
3568 int push_items = 0;
3569 struct btrfs_item *item;
3570 u32 nr;
3571 u32 right_nritems;
3572 u32 data_end;
3573 u32 this_item_size;
3574
3575 if (empty)
3576 nr = 0;
3577 else
3578 nr = max_t(u32, 1, min_slot);
3579
3580 if (path->slots[0] >= left_nritems)
3581 push_space += data_size;
3582
3583 slot = path->slots[1];
3584 i = left_nritems - 1;
3585 while (i >= nr) {
3586 item = btrfs_item_nr(i);
3587
3588 if (!empty && push_items > 0) {
3589 if (path->slots[0] > i)
3590 break;
3591 if (path->slots[0] == i) {
3592 int space = btrfs_leaf_free_space(left);
3593
3594 if (space + push_space * 2 > free_space)
3595 break;
3596 }
3597 }
3598
3599 if (path->slots[0] == i)
3600 push_space += data_size;
3601
3602 this_item_size = btrfs_item_size(left, item);
3603 if (this_item_size + sizeof(*item) + push_space > free_space)
3604 break;
3605
3606 push_items++;
3607 push_space += this_item_size + sizeof(*item);
3608 if (i == 0)
3609 break;
3610 i--;
3611 }
3612
3613 if (push_items == 0)
3614 goto out_unlock;
3615
3616 WARN_ON(!empty && push_items == left_nritems);
3617
3618 /* push left to right */
3619 right_nritems = btrfs_header_nritems(right);
3620
3621 push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3622 push_space -= leaf_data_end(left);
3623
3624 /* make room in the right data area */
3625 data_end = leaf_data_end(right);
3626 memmove_extent_buffer(right,
3627 BTRFS_LEAF_DATA_OFFSET + data_end - push_space,
3628 BTRFS_LEAF_DATA_OFFSET + data_end,
3629 BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
3630
3631 /* copy from the left data area */
3632 copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET +
3633 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3634 BTRFS_LEAF_DATA_OFFSET + leaf_data_end(left),
3635 push_space);
3636
3637 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3638 btrfs_item_nr_offset(0),
3639 right_nritems * sizeof(struct btrfs_item));
3640
3641 /* copy the items from left to right */
3642 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3643 btrfs_item_nr_offset(left_nritems - push_items),
3644 push_items * sizeof(struct btrfs_item));
3645
3646 /* update the item pointers */
3647 btrfs_init_map_token(&token, right);
3648 right_nritems += push_items;
3649 btrfs_set_header_nritems(right, right_nritems);
3650 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3651 for (i = 0; i < right_nritems; i++) {
3652 item = btrfs_item_nr(i);
3653 push_space -= btrfs_token_item_size(&token, item);
3654 btrfs_set_token_item_offset(&token, item, push_space);
3655 }
3656
3657 left_nritems -= push_items;
3658 btrfs_set_header_nritems(left, left_nritems);
3659
3660 if (left_nritems)
3661 btrfs_mark_buffer_dirty(left);
3662 else
3663 btrfs_clean_tree_block(left);
3664
3665 btrfs_mark_buffer_dirty(right);
3666
3667 btrfs_item_key(right, &disk_key, 0);
3668 btrfs_set_node_key(upper, &disk_key, slot + 1);
3669 btrfs_mark_buffer_dirty(upper);
3670
3671 /* then fixup the leaf pointer in the path */
3672 if (path->slots[0] >= left_nritems) {
3673 path->slots[0] -= left_nritems;
3674 if (btrfs_header_nritems(path->nodes[0]) == 0)
3675 btrfs_clean_tree_block(path->nodes[0]);
3676 btrfs_tree_unlock(path->nodes[0]);
3677 free_extent_buffer(path->nodes[0]);
3678 path->nodes[0] = right;
3679 path->slots[1] += 1;
3680 } else {
3681 btrfs_tree_unlock(right);
3682 free_extent_buffer(right);
3683 }
3684 return 0;
3685
3686out_unlock:
3687 btrfs_tree_unlock(right);
3688 free_extent_buffer(right);
3689 return 1;
3690}
3691
3692/*
3693 * push some data in the path leaf to the right, trying to free up at
3694 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3695 *
3696 * returns 1 if the push failed because the other node didn't have enough
3697 * room, 0 if everything worked out and < 0 if there were major errors.
3698 *
3699 * this will push starting from min_slot to the end of the leaf. It won't
3700 * push any slot lower than min_slot
3701 */
3702static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3703 *root, struct btrfs_path *path,
3704 int min_data_size, int data_size,
3705 int empty, u32 min_slot)
3706{
3707 struct extent_buffer *left = path->nodes[0];
3708 struct extent_buffer *right;
3709 struct extent_buffer *upper;
3710 int slot;
3711 int free_space;
3712 u32 left_nritems;
3713 int ret;
3714
3715 if (!path->nodes[1])
3716 return 1;
3717
3718 slot = path->slots[1];
3719 upper = path->nodes[1];
3720 if (slot >= btrfs_header_nritems(upper) - 1)
3721 return 1;
3722
3723 btrfs_assert_tree_locked(path->nodes[1]);
3724
3725 right = btrfs_read_node_slot(upper, slot + 1);
3726 /*
3727 * slot + 1 is not valid or we fail to read the right node,
3728 * no big deal, just return.
3729 */
3730 if (IS_ERR(right))
3731 return 1;
3732
3733 btrfs_tree_lock(right);
3734 btrfs_set_lock_blocking_write(right);
3735
3736 free_space = btrfs_leaf_free_space(right);
3737 if (free_space < data_size)
3738 goto out_unlock;
3739
3740 /* cow and double check */
3741 ret = btrfs_cow_block(trans, root, right, upper,
3742 slot + 1, &right);
3743 if (ret)
3744 goto out_unlock;
3745
3746 free_space = btrfs_leaf_free_space(right);
3747 if (free_space < data_size)
3748 goto out_unlock;
3749
3750 left_nritems = btrfs_header_nritems(left);
3751 if (left_nritems == 0)
3752 goto out_unlock;
3753
3754 if (path->slots[0] == left_nritems && !empty) {
3755 /* Key greater than all keys in the leaf, right neighbor has
3756 * enough room for it and we're not emptying our leaf to delete
3757 * it, therefore use right neighbor to insert the new item and
3758 * no need to touch/dirty our left leaf. */
3759 btrfs_tree_unlock(left);
3760 free_extent_buffer(left);
3761 path->nodes[0] = right;
3762 path->slots[0] = 0;
3763 path->slots[1]++;
3764 return 0;
3765 }
3766
3767 return __push_leaf_right(path, min_data_size, empty,
3768 right, free_space, left_nritems, min_slot);
3769out_unlock:
3770 btrfs_tree_unlock(right);
3771 free_extent_buffer(right);
3772 return 1;
3773}
3774
3775/*
3776 * push some data in the path leaf to the left, trying to free up at
3777 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3778 *
3779 * max_slot can put a limit on how far into the leaf we'll push items. The
3780 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3781 * items
3782 */
3783static noinline int __push_leaf_left(struct btrfs_path *path, int data_size,
3784 int empty, struct extent_buffer *left,
3785 int free_space, u32 right_nritems,
3786 u32 max_slot)
3787{
3788 struct btrfs_fs_info *fs_info = left->fs_info;
3789 struct btrfs_disk_key disk_key;
3790 struct extent_buffer *right = path->nodes[0];
3791 int i;
3792 int push_space = 0;
3793 int push_items = 0;
3794 struct btrfs_item *item;
3795 u32 old_left_nritems;
3796 u32 nr;
3797 int ret = 0;
3798 u32 this_item_size;
3799 u32 old_left_item_size;
3800 struct btrfs_map_token token;
3801
3802 if (empty)
3803 nr = min(right_nritems, max_slot);
3804 else
3805 nr = min(right_nritems - 1, max_slot);
3806
3807 for (i = 0; i < nr; i++) {
3808 item = btrfs_item_nr(i);
3809
3810 if (!empty && push_items > 0) {
3811 if (path->slots[0] < i)
3812 break;
3813 if (path->slots[0] == i) {
3814 int space = btrfs_leaf_free_space(right);
3815
3816 if (space + push_space * 2 > free_space)
3817 break;
3818 }
3819 }
3820
3821 if (path->slots[0] == i)
3822 push_space += data_size;
3823
3824 this_item_size = btrfs_item_size(right, item);
3825 if (this_item_size + sizeof(*item) + push_space > free_space)
3826 break;
3827
3828 push_items++;
3829 push_space += this_item_size + sizeof(*item);
3830 }
3831
3832 if (push_items == 0) {
3833 ret = 1;
3834 goto out;
3835 }
3836 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3837
3838 /* push data from right to left */
3839 copy_extent_buffer(left, right,
3840 btrfs_item_nr_offset(btrfs_header_nritems(left)),
3841 btrfs_item_nr_offset(0),
3842 push_items * sizeof(struct btrfs_item));
3843
3844 push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3845 btrfs_item_offset_nr(right, push_items - 1);
3846
3847 copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET +
3848 leaf_data_end(left) - push_space,
3849 BTRFS_LEAF_DATA_OFFSET +
3850 btrfs_item_offset_nr(right, push_items - 1),
3851 push_space);
3852 old_left_nritems = btrfs_header_nritems(left);
3853 BUG_ON(old_left_nritems <= 0);
3854
3855 btrfs_init_map_token(&token, left);
3856 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3857 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3858 u32 ioff;
3859
3860 item = btrfs_item_nr(i);
3861
3862 ioff = btrfs_token_item_offset(&token, item);
3863 btrfs_set_token_item_offset(&token, item,
3864 ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size));
3865 }
3866 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3867
3868 /* fixup right node */
3869 if (push_items > right_nritems)
3870 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3871 right_nritems);
3872
3873 if (push_items < right_nritems) {
3874 push_space = btrfs_item_offset_nr(right, push_items - 1) -
3875 leaf_data_end(right);
3876 memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET +
3877 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3878 BTRFS_LEAF_DATA_OFFSET +
3879 leaf_data_end(right), push_space);
3880
3881 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3882 btrfs_item_nr_offset(push_items),
3883 (btrfs_header_nritems(right) - push_items) *
3884 sizeof(struct btrfs_item));
3885 }
3886
3887 btrfs_init_map_token(&token, right);
3888 right_nritems -= push_items;
3889 btrfs_set_header_nritems(right, right_nritems);
3890 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3891 for (i = 0; i < right_nritems; i++) {
3892 item = btrfs_item_nr(i);
3893
3894 push_space = push_space - btrfs_token_item_size(&token, item);
3895 btrfs_set_token_item_offset(&token, item, push_space);
3896 }
3897
3898 btrfs_mark_buffer_dirty(left);
3899 if (right_nritems)
3900 btrfs_mark_buffer_dirty(right);
3901 else
3902 btrfs_clean_tree_block(right);
3903
3904 btrfs_item_key(right, &disk_key, 0);
3905 fixup_low_keys(path, &disk_key, 1);
3906
3907 /* then fixup the leaf pointer in the path */
3908 if (path->slots[0] < push_items) {
3909 path->slots[0] += old_left_nritems;
3910 btrfs_tree_unlock(path->nodes[0]);
3911 free_extent_buffer(path->nodes[0]);
3912 path->nodes[0] = left;
3913 path->slots[1] -= 1;
3914 } else {
3915 btrfs_tree_unlock(left);
3916 free_extent_buffer(left);
3917 path->slots[0] -= push_items;
3918 }
3919 BUG_ON(path->slots[0] < 0);
3920 return ret;
3921out:
3922 btrfs_tree_unlock(left);
3923 free_extent_buffer(left);
3924 return ret;
3925}
3926
3927/*
3928 * push some data in the path leaf to the left, trying to free up at
3929 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3930 *
3931 * max_slot can put a limit on how far into the leaf we'll push items. The
3932 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3933 * items
3934 */
3935static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3936 *root, struct btrfs_path *path, int min_data_size,
3937 int data_size, int empty, u32 max_slot)
3938{
3939 struct extent_buffer *right = path->nodes[0];
3940 struct extent_buffer *left;
3941 int slot;
3942 int free_space;
3943 u32 right_nritems;
3944 int ret = 0;
3945
3946 slot = path->slots[1];
3947 if (slot == 0)
3948 return 1;
3949 if (!path->nodes[1])
3950 return 1;
3951
3952 right_nritems = btrfs_header_nritems(right);
3953 if (right_nritems == 0)
3954 return 1;
3955
3956 btrfs_assert_tree_locked(path->nodes[1]);
3957
3958 left = btrfs_read_node_slot(path->nodes[1], slot - 1);
3959 /*
3960 * slot - 1 is not valid or we fail to read the left node,
3961 * no big deal, just return.
3962 */
3963 if (IS_ERR(left))
3964 return 1;
3965
3966 btrfs_tree_lock(left);
3967 btrfs_set_lock_blocking_write(left);
3968
3969 free_space = btrfs_leaf_free_space(left);
3970 if (free_space < data_size) {
3971 ret = 1;
3972 goto out;
3973 }
3974
3975 /* cow and double check */
3976 ret = btrfs_cow_block(trans, root, left,
3977 path->nodes[1], slot - 1, &left);
3978 if (ret) {
3979 /* we hit -ENOSPC, but it isn't fatal here */
3980 if (ret == -ENOSPC)
3981 ret = 1;
3982 goto out;
3983 }
3984
3985 free_space = btrfs_leaf_free_space(left);
3986 if (free_space < data_size) {
3987 ret = 1;
3988 goto out;
3989 }
3990
3991 return __push_leaf_left(path, min_data_size,
3992 empty, left, free_space, right_nritems,
3993 max_slot);
3994out:
3995 btrfs_tree_unlock(left);
3996 free_extent_buffer(left);
3997 return ret;
3998}
3999
4000/*
4001 * split the path's leaf in two, making sure there is at least data_size
4002 * available for the resulting leaf level of the path.
4003 */
4004static noinline void copy_for_split(struct btrfs_trans_handle *trans,
4005 struct btrfs_path *path,
4006 struct extent_buffer *l,
4007 struct extent_buffer *right,
4008 int slot, int mid, int nritems)
4009{
4010 struct btrfs_fs_info *fs_info = trans->fs_info;
4011 int data_copy_size;
4012 int rt_data_off;
4013 int i;
4014 struct btrfs_disk_key disk_key;
4015 struct btrfs_map_token token;
4016
4017 nritems = nritems - mid;
4018 btrfs_set_header_nritems(right, nritems);
4019 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(l);
4020
4021 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
4022 btrfs_item_nr_offset(mid),
4023 nritems * sizeof(struct btrfs_item));
4024
4025 copy_extent_buffer(right, l,
4026 BTRFS_LEAF_DATA_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) -
4027 data_copy_size, BTRFS_LEAF_DATA_OFFSET +
4028 leaf_data_end(l), data_copy_size);
4029
4030 rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_end_nr(l, mid);
4031
4032 btrfs_init_map_token(&token, right);
4033 for (i = 0; i < nritems; i++) {
4034 struct btrfs_item *item = btrfs_item_nr(i);
4035 u32 ioff;
4036
4037 ioff = btrfs_token_item_offset(&token, item);
4038 btrfs_set_token_item_offset(&token, item, ioff + rt_data_off);
4039 }
4040
4041 btrfs_set_header_nritems(l, mid);
4042 btrfs_item_key(right, &disk_key, 0);
4043 insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
4044
4045 btrfs_mark_buffer_dirty(right);
4046 btrfs_mark_buffer_dirty(l);
4047 BUG_ON(path->slots[0] != slot);
4048
4049 if (mid <= slot) {
4050 btrfs_tree_unlock(path->nodes[0]);
4051 free_extent_buffer(path->nodes[0]);
4052 path->nodes[0] = right;
4053 path->slots[0] -= mid;
4054 path->slots[1] += 1;
4055 } else {
4056 btrfs_tree_unlock(right);
4057 free_extent_buffer(right);
4058 }
4059
4060 BUG_ON(path->slots[0] < 0);
4061}
4062
4063/*
4064 * double splits happen when we need to insert a big item in the middle
4065 * of a leaf. A double split can leave us with 3 mostly empty leaves:
4066 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
4067 * A B C
4068 *
4069 * We avoid this by trying to push the items on either side of our target
4070 * into the adjacent leaves. If all goes well we can avoid the double split
4071 * completely.
4072 */
4073static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
4074 struct btrfs_root *root,
4075 struct btrfs_path *path,
4076 int data_size)
4077{
4078 int ret;
4079 int progress = 0;
4080 int slot;
4081 u32 nritems;
4082 int space_needed = data_size;
4083
4084 slot = path->slots[0];
4085 if (slot < btrfs_header_nritems(path->nodes[0]))
4086 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
4087
4088 /*
4089 * try to push all the items after our slot into the
4090 * right leaf
4091 */
4092 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
4093 if (ret < 0)
4094 return ret;
4095
4096 if (ret == 0)
4097 progress++;
4098
4099 nritems = btrfs_header_nritems(path->nodes[0]);
4100 /*
4101 * our goal is to get our slot at the start or end of a leaf. If
4102 * we've done so we're done
4103 */
4104 if (path->slots[0] == 0 || path->slots[0] == nritems)
4105 return 0;
4106
4107 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
4108 return 0;
4109
4110 /* try to push all the items before our slot into the next leaf */
4111 slot = path->slots[0];
4112 space_needed = data_size;
4113 if (slot > 0)
4114 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
4115 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
4116 if (ret < 0)
4117 return ret;
4118
4119 if (ret == 0)
4120 progress++;
4121
4122 if (progress)
4123 return 0;
4124 return 1;
4125}
4126
4127/*
4128 * split the path's leaf in two, making sure there is at least data_size
4129 * available for the resulting leaf level of the path.
4130 *
4131 * returns 0 if all went well and < 0 on failure.
4132 */
4133static noinline int split_leaf(struct btrfs_trans_handle *trans,
4134 struct btrfs_root *root,
4135 const struct btrfs_key *ins_key,
4136 struct btrfs_path *path, int data_size,
4137 int extend)
4138{
4139 struct btrfs_disk_key disk_key;
4140 struct extent_buffer *l;
4141 u32 nritems;
4142 int mid;
4143 int slot;
4144 struct extent_buffer *right;
4145 struct btrfs_fs_info *fs_info = root->fs_info;
4146 int ret = 0;
4147 int wret;
4148 int split;
4149 int num_doubles = 0;
4150 int tried_avoid_double = 0;
4151
4152 l = path->nodes[0];
4153 slot = path->slots[0];
4154 if (extend && data_size + btrfs_item_size_nr(l, slot) +
4155 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
4156 return -EOVERFLOW;
4157
4158 /* first try to make some room by pushing left and right */
4159 if (data_size && path->nodes[1]) {
4160 int space_needed = data_size;
4161
4162 if (slot < btrfs_header_nritems(l))
4163 space_needed -= btrfs_leaf_free_space(l);
4164
4165 wret = push_leaf_right(trans, root, path, space_needed,
4166 space_needed, 0, 0);
4167 if (wret < 0)
4168 return wret;
4169 if (wret) {
4170 space_needed = data_size;
4171 if (slot > 0)
4172 space_needed -= btrfs_leaf_free_space(l);
4173 wret = push_leaf_left(trans, root, path, space_needed,
4174 space_needed, 0, (u32)-1);
4175 if (wret < 0)
4176 return wret;
4177 }
4178 l = path->nodes[0];
4179
4180 /* did the pushes work? */
4181 if (btrfs_leaf_free_space(l) >= data_size)
4182 return 0;
4183 }
4184
4185 if (!path->nodes[1]) {
4186 ret = insert_new_root(trans, root, path, 1);
4187 if (ret)
4188 return ret;
4189 }
4190again:
4191 split = 1;
4192 l = path->nodes[0];
4193 slot = path->slots[0];
4194 nritems = btrfs_header_nritems(l);
4195 mid = (nritems + 1) / 2;
4196
4197 if (mid <= slot) {
4198 if (nritems == 1 ||
4199 leaf_space_used(l, mid, nritems - mid) + data_size >
4200 BTRFS_LEAF_DATA_SIZE(fs_info)) {
4201 if (slot >= nritems) {
4202 split = 0;
4203 } else {
4204 mid = slot;
4205 if (mid != nritems &&
4206 leaf_space_used(l, mid, nritems - mid) +
4207 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4208 if (data_size && !tried_avoid_double)
4209 goto push_for_double;
4210 split = 2;
4211 }
4212 }
4213 }
4214 } else {
4215 if (leaf_space_used(l, 0, mid) + data_size >
4216 BTRFS_LEAF_DATA_SIZE(fs_info)) {
4217 if (!extend && data_size && slot == 0) {
4218 split = 0;
4219 } else if ((extend || !data_size) && slot == 0) {
4220 mid = 1;
4221 } else {
4222 mid = slot;
4223 if (mid != nritems &&
4224 leaf_space_used(l, mid, nritems - mid) +
4225 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4226 if (data_size && !tried_avoid_double)
4227 goto push_for_double;
4228 split = 2;
4229 }
4230 }
4231 }
4232 }
4233
4234 if (split == 0)
4235 btrfs_cpu_key_to_disk(&disk_key, ins_key);
4236 else
4237 btrfs_item_key(l, &disk_key, mid);
4238
4239 right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0,
4240 l->start, 0);
4241 if (IS_ERR(right))
4242 return PTR_ERR(right);
4243
4244 root_add_used(root, fs_info->nodesize);
4245
4246 if (split == 0) {
4247 if (mid <= slot) {
4248 btrfs_set_header_nritems(right, 0);
4249 insert_ptr(trans, path, &disk_key,
4250 right->start, path->slots[1] + 1, 1);
4251 btrfs_tree_unlock(path->nodes[0]);
4252 free_extent_buffer(path->nodes[0]);
4253 path->nodes[0] = right;
4254 path->slots[0] = 0;
4255 path->slots[1] += 1;
4256 } else {
4257 btrfs_set_header_nritems(right, 0);
4258 insert_ptr(trans, path, &disk_key,
4259 right->start, path->slots[1], 1);
4260 btrfs_tree_unlock(path->nodes[0]);
4261 free_extent_buffer(path->nodes[0]);
4262 path->nodes[0] = right;
4263 path->slots[0] = 0;
4264 if (path->slots[1] == 0)
4265 fixup_low_keys(path, &disk_key, 1);
4266 }
4267 /*
4268 * We create a new leaf 'right' for the required ins_len and
4269 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
4270 * the content of ins_len to 'right'.
4271 */
4272 return ret;
4273 }
4274
4275 copy_for_split(trans, path, l, right, slot, mid, nritems);
4276
4277 if (split == 2) {
4278 BUG_ON(num_doubles != 0);
4279 num_doubles++;
4280 goto again;
4281 }
4282
4283 return 0;
4284
4285push_for_double:
4286 push_for_double_split(trans, root, path, data_size);
4287 tried_avoid_double = 1;
4288 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
4289 return 0;
4290 goto again;
4291}
4292
4293static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
4294 struct btrfs_root *root,
4295 struct btrfs_path *path, int ins_len)
4296{
4297 struct btrfs_key key;
4298 struct extent_buffer *leaf;
4299 struct btrfs_file_extent_item *fi;
4300 u64 extent_len = 0;
4301 u32 item_size;
4302 int ret;
4303
4304 leaf = path->nodes[0];
4305 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4306
4307 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
4308 key.type != BTRFS_EXTENT_CSUM_KEY);
4309
4310 if (btrfs_leaf_free_space(leaf) >= ins_len)
4311 return 0;
4312
4313 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4314 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4315 fi = btrfs_item_ptr(leaf, path->slots[0],
4316 struct btrfs_file_extent_item);
4317 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
4318 }
4319 btrfs_release_path(path);
4320
4321 path->keep_locks = 1;
4322 path->search_for_split = 1;
4323 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
4324 path->search_for_split = 0;
4325 if (ret > 0)
4326 ret = -EAGAIN;
4327 if (ret < 0)
4328 goto err;
4329
4330 ret = -EAGAIN;
4331 leaf = path->nodes[0];
4332 /* if our item isn't there, return now */
4333 if (item_size != btrfs_item_size_nr(leaf, path->slots[0]))
4334 goto err;
4335
4336 /* the leaf has changed, it now has room. return now */
4337 if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
4338 goto err;
4339
4340 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4341 fi = btrfs_item_ptr(leaf, path->slots[0],
4342 struct btrfs_file_extent_item);
4343 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
4344 goto err;
4345 }
4346
4347 btrfs_set_path_blocking(path);
4348 ret = split_leaf(trans, root, &key, path, ins_len, 1);
4349 if (ret)
4350 goto err;
4351
4352 path->keep_locks = 0;
4353 btrfs_unlock_up_safe(path, 1);
4354 return 0;
4355err:
4356 path->keep_locks = 0;
4357 return ret;
4358}
4359
4360static noinline int split_item(struct btrfs_path *path,
4361 const struct btrfs_key *new_key,
4362 unsigned long split_offset)
4363{
4364 struct extent_buffer *leaf;
4365 struct btrfs_item *item;
4366 struct btrfs_item *new_item;
4367 int slot;
4368 char *buf;
4369 u32 nritems;
4370 u32 item_size;
4371 u32 orig_offset;
4372 struct btrfs_disk_key disk_key;
4373
4374 leaf = path->nodes[0];
4375 BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));
4376
4377 btrfs_set_path_blocking(path);
4378
4379 item = btrfs_item_nr(path->slots[0]);
4380 orig_offset = btrfs_item_offset(leaf, item);
4381 item_size = btrfs_item_size(leaf, item);
4382
4383 buf = kmalloc(item_size, GFP_NOFS);
4384 if (!buf)
4385 return -ENOMEM;
4386
4387 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
4388 path->slots[0]), item_size);
4389
4390 slot = path->slots[0] + 1;
4391 nritems = btrfs_header_nritems(leaf);
4392 if (slot != nritems) {
4393 /* shift the items */
4394 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
4395 btrfs_item_nr_offset(slot),
4396 (nritems - slot) * sizeof(struct btrfs_item));
4397 }
4398
4399 btrfs_cpu_key_to_disk(&disk_key, new_key);
4400 btrfs_set_item_key(leaf, &disk_key, slot);
4401
4402 new_item = btrfs_item_nr(slot);
4403
4404 btrfs_set_item_offset(leaf, new_item, orig_offset);
4405 btrfs_set_item_size(leaf, new_item, item_size - split_offset);
4406
4407 btrfs_set_item_offset(leaf, item,
4408 orig_offset + item_size - split_offset);
4409 btrfs_set_item_size(leaf, item, split_offset);
4410
4411 btrfs_set_header_nritems(leaf, nritems + 1);
4412
4413 /* write the data for the start of the original item */
4414 write_extent_buffer(leaf, buf,
4415 btrfs_item_ptr_offset(leaf, path->slots[0]),
4416 split_offset);
4417
4418 /* write the data for the new item */
4419 write_extent_buffer(leaf, buf + split_offset,
4420 btrfs_item_ptr_offset(leaf, slot),
4421 item_size - split_offset);
4422 btrfs_mark_buffer_dirty(leaf);
4423
4424 BUG_ON(btrfs_leaf_free_space(leaf) < 0);
4425 kfree(buf);
4426 return 0;
4427}
4428
4429/*
4430 * This function splits a single item into two items,
4431 * giving 'new_key' to the new item and splitting the
4432 * old one at split_offset (from the start of the item).
4433 *
4434 * The path may be released by this operation. After
4435 * the split, the path is pointing to the old item. The
4436 * new item is going to be in the same node as the old one.
4437 *
4438 * Note, the item being split must be smaller enough to live alone on
4439 * a tree block with room for one extra struct btrfs_item
4440 *
4441 * This allows us to split the item in place, keeping a lock on the
4442 * leaf the entire time.
4443 */
4444int btrfs_split_item(struct btrfs_trans_handle *trans,
4445 struct btrfs_root *root,
4446 struct btrfs_path *path,
4447 const struct btrfs_key *new_key,
4448 unsigned long split_offset)
4449{
4450 int ret;
4451 ret = setup_leaf_for_split(trans, root, path,
4452 sizeof(struct btrfs_item));
4453 if (ret)
4454 return ret;
4455
4456 ret = split_item(path, new_key, split_offset);
4457 return ret;
4458}
4459
4460/*
4461 * This function duplicate a item, giving 'new_key' to the new item.
4462 * It guarantees both items live in the same tree leaf and the new item
4463 * is contiguous with the original item.
4464 *
4465 * This allows us to split file extent in place, keeping a lock on the
4466 * leaf the entire time.
4467 */
4468int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4469 struct btrfs_root *root,
4470 struct btrfs_path *path,
4471 const struct btrfs_key *new_key)
4472{
4473 struct extent_buffer *leaf;
4474 int ret;
4475 u32 item_size;
4476
4477 leaf = path->nodes[0];
4478 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4479 ret = setup_leaf_for_split(trans, root, path,
4480 item_size + sizeof(struct btrfs_item));
4481 if (ret)
4482 return ret;
4483
4484 path->slots[0]++;
4485 setup_items_for_insert(root, path, new_key, &item_size,
4486 item_size, item_size +
4487 sizeof(struct btrfs_item), 1);
4488 leaf = path->nodes[0];
4489 memcpy_extent_buffer(leaf,
4490 btrfs_item_ptr_offset(leaf, path->slots[0]),
4491 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4492 item_size);
4493 return 0;
4494}
4495
4496/*
4497 * make the item pointed to by the path smaller. new_size indicates
4498 * how small to make it, and from_end tells us if we just chop bytes
4499 * off the end of the item or if we shift the item to chop bytes off
4500 * the front.
4501 */
4502void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end)
4503{
4504 int slot;
4505 struct extent_buffer *leaf;
4506 struct btrfs_item *item;
4507 u32 nritems;
4508 unsigned int data_end;
4509 unsigned int old_data_start;
4510 unsigned int old_size;
4511 unsigned int size_diff;
4512 int i;
4513 struct btrfs_map_token token;
4514
4515 leaf = path->nodes[0];
4516 slot = path->slots[0];
4517
4518 old_size = btrfs_item_size_nr(leaf, slot);
4519 if (old_size == new_size)
4520 return;
4521
4522 nritems = btrfs_header_nritems(leaf);
4523 data_end = leaf_data_end(leaf);
4524
4525 old_data_start = btrfs_item_offset_nr(leaf, slot);
4526
4527 size_diff = old_size - new_size;
4528
4529 BUG_ON(slot < 0);
4530 BUG_ON(slot >= nritems);
4531
4532 /*
4533 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4534 */
4535 /* first correct the data pointers */
4536 btrfs_init_map_token(&token, leaf);
4537 for (i = slot; i < nritems; i++) {
4538 u32 ioff;
4539 item = btrfs_item_nr(i);
4540
4541 ioff = btrfs_token_item_offset(&token, item);
4542 btrfs_set_token_item_offset(&token, item, ioff + size_diff);
4543 }
4544
4545 /* shift the data */
4546 if (from_end) {
4547 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4548 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4549 data_end, old_data_start + new_size - data_end);
4550 } else {
4551 struct btrfs_disk_key disk_key;
4552 u64 offset;
4553
4554 btrfs_item_key(leaf, &disk_key, slot);
4555
4556 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4557 unsigned long ptr;
4558 struct btrfs_file_extent_item *fi;
4559
4560 fi = btrfs_item_ptr(leaf, slot,
4561 struct btrfs_file_extent_item);
4562 fi = (struct btrfs_file_extent_item *)(
4563 (unsigned long)fi - size_diff);
4564
4565 if (btrfs_file_extent_type(leaf, fi) ==
4566 BTRFS_FILE_EXTENT_INLINE) {
4567 ptr = btrfs_item_ptr_offset(leaf, slot);
4568 memmove_extent_buffer(leaf, ptr,
4569 (unsigned long)fi,
4570 BTRFS_FILE_EXTENT_INLINE_DATA_START);
4571 }
4572 }
4573
4574 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4575 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4576 data_end, old_data_start - data_end);
4577
4578 offset = btrfs_disk_key_offset(&disk_key);
4579 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4580 btrfs_set_item_key(leaf, &disk_key, slot);
4581 if (slot == 0)
4582 fixup_low_keys(path, &disk_key, 1);
4583 }
4584
4585 item = btrfs_item_nr(slot);
4586 btrfs_set_item_size(leaf, item, new_size);
4587 btrfs_mark_buffer_dirty(leaf);
4588
4589 if (btrfs_leaf_free_space(leaf) < 0) {
4590 btrfs_print_leaf(leaf);
4591 BUG();
4592 }
4593}
4594
4595/*
4596 * make the item pointed to by the path bigger, data_size is the added size.
4597 */
4598void btrfs_extend_item(struct btrfs_path *path, u32 data_size)
4599{
4600 int slot;
4601 struct extent_buffer *leaf;
4602 struct btrfs_item *item;
4603 u32 nritems;
4604 unsigned int data_end;
4605 unsigned int old_data;
4606 unsigned int old_size;
4607 int i;
4608 struct btrfs_map_token token;
4609
4610 leaf = path->nodes[0];
4611
4612 nritems = btrfs_header_nritems(leaf);
4613 data_end = leaf_data_end(leaf);
4614
4615 if (btrfs_leaf_free_space(leaf) < data_size) {
4616 btrfs_print_leaf(leaf);
4617 BUG();
4618 }
4619 slot = path->slots[0];
4620 old_data = btrfs_item_end_nr(leaf, slot);
4621
4622 BUG_ON(slot < 0);
4623 if (slot >= nritems) {
4624 btrfs_print_leaf(leaf);
4625 btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
4626 slot, nritems);
4627 BUG();
4628 }
4629
4630 /*
4631 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4632 */
4633 /* first correct the data pointers */
4634 btrfs_init_map_token(&token, leaf);
4635 for (i = slot; i < nritems; i++) {
4636 u32 ioff;
4637 item = btrfs_item_nr(i);
4638
4639 ioff = btrfs_token_item_offset(&token, item);
4640 btrfs_set_token_item_offset(&token, item, ioff - data_size);
4641 }
4642
4643 /* shift the data */
4644 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4645 data_end - data_size, BTRFS_LEAF_DATA_OFFSET +
4646 data_end, old_data - data_end);
4647
4648 data_end = old_data;
4649 old_size = btrfs_item_size_nr(leaf, slot);
4650 item = btrfs_item_nr(slot);
4651 btrfs_set_item_size(leaf, item, old_size + data_size);
4652 btrfs_mark_buffer_dirty(leaf);
4653
4654 if (btrfs_leaf_free_space(leaf) < 0) {
4655 btrfs_print_leaf(leaf);
4656 BUG();
4657 }
4658}
4659
4660/*
4661 * this is a helper for btrfs_insert_empty_items, the main goal here is
4662 * to save stack depth by doing the bulk of the work in a function
4663 * that doesn't call btrfs_search_slot
4664 */
4665void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
4666 const struct btrfs_key *cpu_key, u32 *data_size,
4667 u32 total_data, u32 total_size, int nr)
4668{
4669 struct btrfs_fs_info *fs_info = root->fs_info;
4670 struct btrfs_item *item;
4671 int i;
4672 u32 nritems;
4673 unsigned int data_end;
4674 struct btrfs_disk_key disk_key;
4675 struct extent_buffer *leaf;
4676 int slot;
4677 struct btrfs_map_token token;
4678
4679 if (path->slots[0] == 0) {
4680 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4681 fixup_low_keys(path, &disk_key, 1);
4682 }
4683 btrfs_unlock_up_safe(path, 1);
4684
4685 leaf = path->nodes[0];
4686 slot = path->slots[0];
4687
4688 nritems = btrfs_header_nritems(leaf);
4689 data_end = leaf_data_end(leaf);
4690
4691 if (btrfs_leaf_free_space(leaf) < total_size) {
4692 btrfs_print_leaf(leaf);
4693 btrfs_crit(fs_info, "not enough freespace need %u have %d",
4694 total_size, btrfs_leaf_free_space(leaf));
4695 BUG();
4696 }
4697
4698 btrfs_init_map_token(&token, leaf);
4699 if (slot != nritems) {
4700 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4701
4702 if (old_data < data_end) {
4703 btrfs_print_leaf(leaf);
4704 btrfs_crit(fs_info, "slot %d old_data %d data_end %d",
4705 slot, old_data, data_end);
4706 BUG();
4707 }
4708 /*
4709 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4710 */
4711 /* first correct the data pointers */
4712 for (i = slot; i < nritems; i++) {
4713 u32 ioff;
4714
4715 item = btrfs_item_nr(i);
4716 ioff = btrfs_token_item_offset(&token, item);
4717 btrfs_set_token_item_offset(&token, item,
4718 ioff - total_data);
4719 }
4720 /* shift the items */
4721 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4722 btrfs_item_nr_offset(slot),
4723 (nritems - slot) * sizeof(struct btrfs_item));
4724
4725 /* shift the data */
4726 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4727 data_end - total_data, BTRFS_LEAF_DATA_OFFSET +
4728 data_end, old_data - data_end);
4729 data_end = old_data;
4730 }
4731
4732 /* setup the item for the new data */
4733 for (i = 0; i < nr; i++) {
4734 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4735 btrfs_set_item_key(leaf, &disk_key, slot + i);
4736 item = btrfs_item_nr(slot + i);
4737 btrfs_set_token_item_offset(&token, item, data_end - data_size[i]);
4738 data_end -= data_size[i];
4739 btrfs_set_token_item_size(&token, item, data_size[i]);
4740 }
4741
4742 btrfs_set_header_nritems(leaf, nritems + nr);
4743 btrfs_mark_buffer_dirty(leaf);
4744
4745 if (btrfs_leaf_free_space(leaf) < 0) {
4746 btrfs_print_leaf(leaf);
4747 BUG();
4748 }
4749}
4750
4751/*
4752 * Given a key and some data, insert items into the tree.
4753 * This does all the path init required, making room in the tree if needed.
4754 */
4755int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4756 struct btrfs_root *root,
4757 struct btrfs_path *path,
4758 const struct btrfs_key *cpu_key, u32 *data_size,
4759 int nr)
4760{
4761 int ret = 0;
4762 int slot;
4763 int i;
4764 u32 total_size = 0;
4765 u32 total_data = 0;
4766
4767 for (i = 0; i < nr; i++)
4768 total_data += data_size[i];
4769
4770 total_size = total_data + (nr * sizeof(struct btrfs_item));
4771 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4772 if (ret == 0)
4773 return -EEXIST;
4774 if (ret < 0)
4775 return ret;
4776
4777 slot = path->slots[0];
4778 BUG_ON(slot < 0);
4779
4780 setup_items_for_insert(root, path, cpu_key, data_size,
4781 total_data, total_size, nr);
4782 return 0;
4783}
4784
4785/*
4786 * Given a key and some data, insert an item into the tree.
4787 * This does all the path init required, making room in the tree if needed.
4788 */
4789int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4790 const struct btrfs_key *cpu_key, void *data,
4791 u32 data_size)
4792{
4793 int ret = 0;
4794 struct btrfs_path *path;
4795 struct extent_buffer *leaf;
4796 unsigned long ptr;
4797
4798 path = btrfs_alloc_path();
4799 if (!path)
4800 return -ENOMEM;
4801 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4802 if (!ret) {
4803 leaf = path->nodes[0];
4804 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4805 write_extent_buffer(leaf, data, ptr, data_size);
4806 btrfs_mark_buffer_dirty(leaf);
4807 }
4808 btrfs_free_path(path);
4809 return ret;
4810}
4811
4812/*
4813 * delete the pointer from a given node.
4814 *
4815 * the tree should have been previously balanced so the deletion does not
4816 * empty a node.
4817 */
4818static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
4819 int level, int slot)
4820{
4821 struct extent_buffer *parent = path->nodes[level];
4822 u32 nritems;
4823 int ret;
4824
4825 nritems = btrfs_header_nritems(parent);
4826 if (slot != nritems - 1) {
4827 if (level) {
4828 ret = tree_mod_log_insert_move(parent, slot, slot + 1,
4829 nritems - slot - 1);
4830 BUG_ON(ret < 0);
4831 }
4832 memmove_extent_buffer(parent,
4833 btrfs_node_key_ptr_offset(slot),
4834 btrfs_node_key_ptr_offset(slot + 1),
4835 sizeof(struct btrfs_key_ptr) *
4836 (nritems - slot - 1));
4837 } else if (level) {
4838 ret = tree_mod_log_insert_key(parent, slot, MOD_LOG_KEY_REMOVE,
4839 GFP_NOFS);
4840 BUG_ON(ret < 0);
4841 }
4842
4843 nritems--;
4844 btrfs_set_header_nritems(parent, nritems);
4845 if (nritems == 0 && parent == root->node) {
4846 BUG_ON(btrfs_header_level(root->node) != 1);
4847 /* just turn the root into a leaf and break */
4848 btrfs_set_header_level(root->node, 0);
4849 } else if (slot == 0) {
4850 struct btrfs_disk_key disk_key;
4851
4852 btrfs_node_key(parent, &disk_key, 0);
4853 fixup_low_keys(path, &disk_key, level + 1);
4854 }
4855 btrfs_mark_buffer_dirty(parent);
4856}
4857
4858/*
4859 * a helper function to delete the leaf pointed to by path->slots[1] and
4860 * path->nodes[1].
4861 *
4862 * This deletes the pointer in path->nodes[1] and frees the leaf
4863 * block extent. zero is returned if it all worked out, < 0 otherwise.
4864 *
4865 * The path must have already been setup for deleting the leaf, including
4866 * all the proper balancing. path->nodes[1] must be locked.
4867 */
4868static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4869 struct btrfs_root *root,
4870 struct btrfs_path *path,
4871 struct extent_buffer *leaf)
4872{
4873 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4874 del_ptr(root, path, 1, path->slots[1]);
4875
4876 /*
4877 * btrfs_free_extent is expensive, we want to make sure we
4878 * aren't holding any locks when we call it
4879 */
4880 btrfs_unlock_up_safe(path, 0);
4881
4882 root_sub_used(root, leaf->len);
4883
4884 atomic_inc(&leaf->refs);
4885 btrfs_free_tree_block(trans, root, leaf, 0, 1);
4886 free_extent_buffer_stale(leaf);
4887}
4888/*
4889 * delete the item at the leaf level in path. If that empties
4890 * the leaf, remove it from the tree
4891 */
4892int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4893 struct btrfs_path *path, int slot, int nr)
4894{
4895 struct btrfs_fs_info *fs_info = root->fs_info;
4896 struct extent_buffer *leaf;
4897 struct btrfs_item *item;
4898 u32 last_off;
4899 u32 dsize = 0;
4900 int ret = 0;
4901 int wret;
4902 int i;
4903 u32 nritems;
4904
4905 leaf = path->nodes[0];
4906 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4907
4908 for (i = 0; i < nr; i++)
4909 dsize += btrfs_item_size_nr(leaf, slot + i);
4910
4911 nritems = btrfs_header_nritems(leaf);
4912
4913 if (slot + nr != nritems) {
4914 int data_end = leaf_data_end(leaf);
4915 struct btrfs_map_token token;
4916
4917 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4918 data_end + dsize,
4919 BTRFS_LEAF_DATA_OFFSET + data_end,
4920 last_off - data_end);
4921
4922 btrfs_init_map_token(&token, leaf);
4923 for (i = slot + nr; i < nritems; i++) {
4924 u32 ioff;
4925
4926 item = btrfs_item_nr(i);
4927 ioff = btrfs_token_item_offset(&token, item);
4928 btrfs_set_token_item_offset(&token, item, ioff + dsize);
4929 }
4930
4931 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
4932 btrfs_item_nr_offset(slot + nr),
4933 sizeof(struct btrfs_item) *
4934 (nritems - slot - nr));
4935 }
4936 btrfs_set_header_nritems(leaf, nritems - nr);
4937 nritems -= nr;
4938
4939 /* delete the leaf if we've emptied it */
4940 if (nritems == 0) {
4941 if (leaf == root->node) {
4942 btrfs_set_header_level(leaf, 0);
4943 } else {
4944 btrfs_set_path_blocking(path);
4945 btrfs_clean_tree_block(leaf);
4946 btrfs_del_leaf(trans, root, path, leaf);
4947 }
4948 } else {
4949 int used = leaf_space_used(leaf, 0, nritems);
4950 if (slot == 0) {
4951 struct btrfs_disk_key disk_key;
4952
4953 btrfs_item_key(leaf, &disk_key, 0);
4954 fixup_low_keys(path, &disk_key, 1);
4955 }
4956
4957 /* delete the leaf if it is mostly empty */
4958 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
4959 /* push_leaf_left fixes the path.
4960 * make sure the path still points to our leaf
4961 * for possible call to del_ptr below
4962 */
4963 slot = path->slots[1];
4964 atomic_inc(&leaf->refs);
4965
4966 btrfs_set_path_blocking(path);
4967 wret = push_leaf_left(trans, root, path, 1, 1,
4968 1, (u32)-1);
4969 if (wret < 0 && wret != -ENOSPC)
4970 ret = wret;
4971
4972 if (path->nodes[0] == leaf &&
4973 btrfs_header_nritems(leaf)) {
4974 wret = push_leaf_right(trans, root, path, 1,
4975 1, 1, 0);
4976 if (wret < 0 && wret != -ENOSPC)
4977 ret = wret;
4978 }
4979
4980 if (btrfs_header_nritems(leaf) == 0) {
4981 path->slots[1] = slot;
4982 btrfs_del_leaf(trans, root, path, leaf);
4983 free_extent_buffer(leaf);
4984 ret = 0;
4985 } else {
4986 /* if we're still in the path, make sure
4987 * we're dirty. Otherwise, one of the
4988 * push_leaf functions must have already
4989 * dirtied this buffer
4990 */
4991 if (path->nodes[0] == leaf)
4992 btrfs_mark_buffer_dirty(leaf);
4993 free_extent_buffer(leaf);
4994 }
4995 } else {
4996 btrfs_mark_buffer_dirty(leaf);
4997 }
4998 }
4999 return ret;
5000}
5001
5002/*
5003 * search the tree again to find a leaf with lesser keys
5004 * returns 0 if it found something or 1 if there are no lesser leaves.
5005 * returns < 0 on io errors.
5006 *
5007 * This may release the path, and so you may lose any locks held at the
5008 * time you call it.
5009 */
5010int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
5011{
5012 struct btrfs_key key;
5013 struct btrfs_disk_key found_key;
5014 int ret;
5015
5016 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
5017
5018 if (key.offset > 0) {
5019 key.offset--;
5020 } else if (key.type > 0) {
5021 key.type--;
5022 key.offset = (u64)-1;
5023 } else if (key.objectid > 0) {
5024 key.objectid--;
5025 key.type = (u8)-1;
5026 key.offset = (u64)-1;
5027 } else {
5028 return 1;
5029 }
5030
5031 btrfs_release_path(path);
5032 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5033 if (ret < 0)
5034 return ret;
5035 btrfs_item_key(path->nodes[0], &found_key, 0);
5036 ret = comp_keys(&found_key, &key);
5037 /*
5038 * We might have had an item with the previous key in the tree right
5039 * before we released our path. And after we released our path, that
5040 * item might have been pushed to the first slot (0) of the leaf we
5041 * were holding due to a tree balance. Alternatively, an item with the
5042 * previous key can exist as the only element of a leaf (big fat item).
5043 * Therefore account for these 2 cases, so that our callers (like
5044 * btrfs_previous_item) don't miss an existing item with a key matching
5045 * the previous key we computed above.
5046 */
5047 if (ret <= 0)
5048 return 0;
5049 return 1;
5050}
5051
5052/*
5053 * A helper function to walk down the tree starting at min_key, and looking
5054 * for nodes or leaves that are have a minimum transaction id.
5055 * This is used by the btree defrag code, and tree logging
5056 *
5057 * This does not cow, but it does stuff the starting key it finds back
5058 * into min_key, so you can call btrfs_search_slot with cow=1 on the
5059 * key and get a writable path.
5060 *
5061 * This honors path->lowest_level to prevent descent past a given level
5062 * of the tree.
5063 *
5064 * min_trans indicates the oldest transaction that you are interested
5065 * in walking through. Any nodes or leaves older than min_trans are
5066 * skipped over (without reading them).
5067 *
5068 * returns zero if something useful was found, < 0 on error and 1 if there
5069 * was nothing in the tree that matched the search criteria.
5070 */
5071int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
5072 struct btrfs_path *path,
5073 u64 min_trans)
5074{
5075 struct extent_buffer *cur;
5076 struct btrfs_key found_key;
5077 int slot;
5078 int sret;
5079 u32 nritems;
5080 int level;
5081 int ret = 1;
5082 int keep_locks = path->keep_locks;
5083
5084 path->keep_locks = 1;
5085again:
5086 cur = btrfs_read_lock_root_node(root);
5087 level = btrfs_header_level(cur);
5088 WARN_ON(path->nodes[level]);
5089 path->nodes[level] = cur;
5090 path->locks[level] = BTRFS_READ_LOCK;
5091
5092 if (btrfs_header_generation(cur) < min_trans) {
5093 ret = 1;
5094 goto out;
5095 }
5096 while (1) {
5097 nritems = btrfs_header_nritems(cur);
5098 level = btrfs_header_level(cur);
5099 sret = btrfs_bin_search(cur, min_key, &slot);
5100 if (sret < 0) {
5101 ret = sret;
5102 goto out;
5103 }
5104
5105 /* at the lowest level, we're done, setup the path and exit */
5106 if (level == path->lowest_level) {
5107 if (slot >= nritems)
5108 goto find_next_key;
5109 ret = 0;
5110 path->slots[level] = slot;
5111 btrfs_item_key_to_cpu(cur, &found_key, slot);
5112 goto out;
5113 }
5114 if (sret && slot > 0)
5115 slot--;
5116 /*
5117 * check this node pointer against the min_trans parameters.
5118 * If it is too old, old, skip to the next one.
5119 */
5120 while (slot < nritems) {
5121 u64 gen;
5122
5123 gen = btrfs_node_ptr_generation(cur, slot);
5124 if (gen < min_trans) {
5125 slot++;
5126 continue;
5127 }
5128 break;
5129 }
5130find_next_key:
5131 /*
5132 * we didn't find a candidate key in this node, walk forward
5133 * and find another one
5134 */
5135 if (slot >= nritems) {
5136 path->slots[level] = slot;
5137 btrfs_set_path_blocking(path);
5138 sret = btrfs_find_next_key(root, path, min_key, level,
5139 min_trans);
5140 if (sret == 0) {
5141 btrfs_release_path(path);
5142 goto again;
5143 } else {
5144 goto out;
5145 }
5146 }
5147 /* save our key for returning back */
5148 btrfs_node_key_to_cpu(cur, &found_key, slot);
5149 path->slots[level] = slot;
5150 if (level == path->lowest_level) {
5151 ret = 0;
5152 goto out;
5153 }
5154 btrfs_set_path_blocking(path);
5155 cur = btrfs_read_node_slot(cur, slot);
5156 if (IS_ERR(cur)) {
5157 ret = PTR_ERR(cur);
5158 goto out;
5159 }
5160
5161 btrfs_tree_read_lock(cur);
5162
5163 path->locks[level - 1] = BTRFS_READ_LOCK;
5164 path->nodes[level - 1] = cur;
5165 unlock_up(path, level, 1, 0, NULL);
5166 }
5167out:
5168 path->keep_locks = keep_locks;
5169 if (ret == 0) {
5170 btrfs_unlock_up_safe(path, path->lowest_level + 1);
5171 btrfs_set_path_blocking(path);
5172 memcpy(min_key, &found_key, sizeof(found_key));
5173 }
5174 return ret;
5175}
5176
5177/*
5178 * this is similar to btrfs_next_leaf, but does not try to preserve
5179 * and fixup the path. It looks for and returns the next key in the
5180 * tree based on the current path and the min_trans parameters.
5181 *
5182 * 0 is returned if another key is found, < 0 if there are any errors
5183 * and 1 is returned if there are no higher keys in the tree
5184 *
5185 * path->keep_locks should be set to 1 on the search made before
5186 * calling this function.
5187 */
5188int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
5189 struct btrfs_key *key, int level, u64 min_trans)
5190{
5191 int slot;
5192 struct extent_buffer *c;
5193
5194 WARN_ON(!path->keep_locks && !path->skip_locking);
5195 while (level < BTRFS_MAX_LEVEL) {
5196 if (!path->nodes[level])
5197 return 1;
5198
5199 slot = path->slots[level] + 1;
5200 c = path->nodes[level];
5201next:
5202 if (slot >= btrfs_header_nritems(c)) {
5203 int ret;
5204 int orig_lowest;
5205 struct btrfs_key cur_key;
5206 if (level + 1 >= BTRFS_MAX_LEVEL ||
5207 !path->nodes[level + 1])
5208 return 1;
5209
5210 if (path->locks[level + 1] || path->skip_locking) {
5211 level++;
5212 continue;
5213 }
5214
5215 slot = btrfs_header_nritems(c) - 1;
5216 if (level == 0)
5217 btrfs_item_key_to_cpu(c, &cur_key, slot);
5218 else
5219 btrfs_node_key_to_cpu(c, &cur_key, slot);
5220
5221 orig_lowest = path->lowest_level;
5222 btrfs_release_path(path);
5223 path->lowest_level = level;
5224 ret = btrfs_search_slot(NULL, root, &cur_key, path,
5225 0, 0);
5226 path->lowest_level = orig_lowest;
5227 if (ret < 0)
5228 return ret;
5229
5230 c = path->nodes[level];
5231 slot = path->slots[level];
5232 if (ret == 0)
5233 slot++;
5234 goto next;
5235 }
5236
5237 if (level == 0)
5238 btrfs_item_key_to_cpu(c, key, slot);
5239 else {
5240 u64 gen = btrfs_node_ptr_generation(c, slot);
5241
5242 if (gen < min_trans) {
5243 slot++;
5244 goto next;
5245 }
5246 btrfs_node_key_to_cpu(c, key, slot);
5247 }
5248 return 0;
5249 }
5250 return 1;
5251}
5252
5253/*
5254 * search the tree again to find a leaf with greater keys
5255 * returns 0 if it found something or 1 if there are no greater leaves.
5256 * returns < 0 on io errors.
5257 */
5258int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
5259{
5260 return btrfs_next_old_leaf(root, path, 0);
5261}
5262
5263int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
5264 u64 time_seq)
5265{
5266 int slot;
5267 int level;
5268 struct extent_buffer *c;
5269 struct extent_buffer *next;
5270 struct btrfs_key key;
5271 u32 nritems;
5272 int ret;
5273 int old_spinning = path->leave_spinning;
5274 int next_rw_lock = 0;
5275
5276 nritems = btrfs_header_nritems(path->nodes[0]);
5277 if (nritems == 0)
5278 return 1;
5279
5280 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5281again:
5282 level = 1;
5283 next = NULL;
5284 next_rw_lock = 0;
5285 btrfs_release_path(path);
5286
5287 path->keep_locks = 1;
5288 path->leave_spinning = 1;
5289
5290 if (time_seq)
5291 ret = btrfs_search_old_slot(root, &key, path, time_seq);
5292 else
5293 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5294 path->keep_locks = 0;
5295
5296 if (ret < 0)
5297 return ret;
5298
5299 nritems = btrfs_header_nritems(path->nodes[0]);
5300 /*
5301 * by releasing the path above we dropped all our locks. A balance
5302 * could have added more items next to the key that used to be
5303 * at the very end of the block. So, check again here and
5304 * advance the path if there are now more items available.
5305 */
5306 if (nritems > 0 && path->slots[0] < nritems - 1) {
5307 if (ret == 0)
5308 path->slots[0]++;
5309 ret = 0;
5310 goto done;
5311 }
5312 /*
5313 * So the above check misses one case:
5314 * - after releasing the path above, someone has removed the item that
5315 * used to be at the very end of the block, and balance between leafs
5316 * gets another one with bigger key.offset to replace it.
5317 *
5318 * This one should be returned as well, or we can get leaf corruption
5319 * later(esp. in __btrfs_drop_extents()).
5320 *
5321 * And a bit more explanation about this check,
5322 * with ret > 0, the key isn't found, the path points to the slot
5323 * where it should be inserted, so the path->slots[0] item must be the
5324 * bigger one.
5325 */
5326 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
5327 ret = 0;
5328 goto done;
5329 }
5330
5331 while (level < BTRFS_MAX_LEVEL) {
5332 if (!path->nodes[level]) {
5333 ret = 1;
5334 goto done;
5335 }
5336
5337 slot = path->slots[level] + 1;
5338 c = path->nodes[level];
5339 if (slot >= btrfs_header_nritems(c)) {
5340 level++;
5341 if (level == BTRFS_MAX_LEVEL) {
5342 ret = 1;
5343 goto done;
5344 }
5345 continue;
5346 }
5347
5348 if (next) {
5349 btrfs_tree_unlock_rw(next, next_rw_lock);
5350 free_extent_buffer(next);
5351 }
5352
5353 next = c;
5354 next_rw_lock = path->locks[level];
5355 ret = read_block_for_search(root, path, &next, level,
5356 slot, &key);
5357 if (ret == -EAGAIN)
5358 goto again;
5359
5360 if (ret < 0) {
5361 btrfs_release_path(path);
5362 goto done;
5363 }
5364
5365 if (!path->skip_locking) {
5366 ret = btrfs_try_tree_read_lock(next);
5367 if (!ret && time_seq) {
5368 /*
5369 * If we don't get the lock, we may be racing
5370 * with push_leaf_left, holding that lock while
5371 * itself waiting for the leaf we've currently
5372 * locked. To solve this situation, we give up
5373 * on our lock and cycle.
5374 */
5375 free_extent_buffer(next);
5376 btrfs_release_path(path);
5377 cond_resched();
5378 goto again;
5379 }
5380 if (!ret) {
5381 btrfs_set_path_blocking(path);
5382 btrfs_tree_read_lock(next);
5383 }
5384 next_rw_lock = BTRFS_READ_LOCK;
5385 }
5386 break;
5387 }
5388 path->slots[level] = slot;
5389 while (1) {
5390 level--;
5391 c = path->nodes[level];
5392 if (path->locks[level])
5393 btrfs_tree_unlock_rw(c, path->locks[level]);
5394
5395 free_extent_buffer(c);
5396 path->nodes[level] = next;
5397 path->slots[level] = 0;
5398 if (!path->skip_locking)
5399 path->locks[level] = next_rw_lock;
5400 if (!level)
5401 break;
5402
5403 ret = read_block_for_search(root, path, &next, level,
5404 0, &key);
5405 if (ret == -EAGAIN)
5406 goto again;
5407
5408 if (ret < 0) {
5409 btrfs_release_path(path);
5410 goto done;
5411 }
5412
5413 if (!path->skip_locking) {
5414 ret = btrfs_try_tree_read_lock(next);
5415 if (!ret) {
5416 btrfs_set_path_blocking(path);
5417 btrfs_tree_read_lock(next);
5418 }
5419 next_rw_lock = BTRFS_READ_LOCK;
5420 }
5421 }
5422 ret = 0;
5423done:
5424 unlock_up(path, 0, 1, 0, NULL);
5425 path->leave_spinning = old_spinning;
5426 if (!old_spinning)
5427 btrfs_set_path_blocking(path);
5428
5429 return ret;
5430}
5431
5432/*
5433 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5434 * searching until it gets past min_objectid or finds an item of 'type'
5435 *
5436 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5437 */
5438int btrfs_previous_item(struct btrfs_root *root,
5439 struct btrfs_path *path, u64 min_objectid,
5440 int type)
5441{
5442 struct btrfs_key found_key;
5443 struct extent_buffer *leaf;
5444 u32 nritems;
5445 int ret;
5446
5447 while (1) {
5448 if (path->slots[0] == 0) {
5449 btrfs_set_path_blocking(path);
5450 ret = btrfs_prev_leaf(root, path);
5451 if (ret != 0)
5452 return ret;
5453 } else {
5454 path->slots[0]--;
5455 }
5456 leaf = path->nodes[0];
5457 nritems = btrfs_header_nritems(leaf);
5458 if (nritems == 0)
5459 return 1;
5460 if (path->slots[0] == nritems)
5461 path->slots[0]--;
5462
5463 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5464 if (found_key.objectid < min_objectid)
5465 break;
5466 if (found_key.type == type)
5467 return 0;
5468 if (found_key.objectid == min_objectid &&
5469 found_key.type < type)
5470 break;
5471 }
5472 return 1;
5473}
5474
5475/*
5476 * search in extent tree to find a previous Metadata/Data extent item with
5477 * min objecitd.
5478 *
5479 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5480 */
5481int btrfs_previous_extent_item(struct btrfs_root *root,
5482 struct btrfs_path *path, u64 min_objectid)
5483{
5484 struct btrfs_key found_key;
5485 struct extent_buffer *leaf;
5486 u32 nritems;
5487 int ret;
5488
5489 while (1) {
5490 if (path->slots[0] == 0) {
5491 btrfs_set_path_blocking(path);
5492 ret = btrfs_prev_leaf(root, path);
5493 if (ret != 0)
5494 return ret;
5495 } else {
5496 path->slots[0]--;
5497 }
5498 leaf = path->nodes[0];
5499 nritems = btrfs_header_nritems(leaf);
5500 if (nritems == 0)
5501 return 1;
5502 if (path->slots[0] == nritems)
5503 path->slots[0]--;
5504
5505 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5506 if (found_key.objectid < min_objectid)
5507 break;
5508 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5509 found_key.type == BTRFS_METADATA_ITEM_KEY)
5510 return 0;
5511 if (found_key.objectid == min_objectid &&
5512 found_key.type < BTRFS_EXTENT_ITEM_KEY)
5513 break;
5514 }
5515 return 1;
5516}