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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/*
2 * Copyright (C) 2007,2008 Oracle. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19#include <linux/sched.h>
20#include <linux/slab.h>
21#include <linux/rbtree.h>
22#include "ctree.h"
23#include "disk-io.h"
24#include "transaction.h"
25#include "print-tree.h"
26#include "locking.h"
27
28static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
29 *root, struct btrfs_path *path, int level);
30static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
31 *root, struct btrfs_key *ins_key,
32 struct btrfs_path *path, int data_size, int extend);
33static int push_node_left(struct btrfs_trans_handle *trans,
34 struct btrfs_root *root, struct extent_buffer *dst,
35 struct extent_buffer *src, int empty);
36static int balance_node_right(struct btrfs_trans_handle *trans,
37 struct btrfs_root *root,
38 struct extent_buffer *dst_buf,
39 struct extent_buffer *src_buf);
40static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
41 int level, int slot);
42static int tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
43 struct extent_buffer *eb);
44
45struct btrfs_path *btrfs_alloc_path(void)
46{
47 struct btrfs_path *path;
48 path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
49 return path;
50}
51
52/*
53 * set all locked nodes in the path to blocking locks. This should
54 * be done before scheduling
55 */
56noinline void btrfs_set_path_blocking(struct btrfs_path *p)
57{
58 int i;
59 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
60 if (!p->nodes[i] || !p->locks[i])
61 continue;
62 btrfs_set_lock_blocking_rw(p->nodes[i], p->locks[i]);
63 if (p->locks[i] == BTRFS_READ_LOCK)
64 p->locks[i] = BTRFS_READ_LOCK_BLOCKING;
65 else if (p->locks[i] == BTRFS_WRITE_LOCK)
66 p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING;
67 }
68}
69
70/*
71 * reset all the locked nodes in the patch to spinning locks.
72 *
73 * held is used to keep lockdep happy, when lockdep is enabled
74 * we set held to a blocking lock before we go around and
75 * retake all the spinlocks in the path. You can safely use NULL
76 * for held
77 */
78noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
79 struct extent_buffer *held, int held_rw)
80{
81 int i;
82
83#ifdef CONFIG_DEBUG_LOCK_ALLOC
84 /* lockdep really cares that we take all of these spinlocks
85 * in the right order. If any of the locks in the path are not
86 * currently blocking, it is going to complain. So, make really
87 * really sure by forcing the path to blocking before we clear
88 * the path blocking.
89 */
90 if (held) {
91 btrfs_set_lock_blocking_rw(held, held_rw);
92 if (held_rw == BTRFS_WRITE_LOCK)
93 held_rw = BTRFS_WRITE_LOCK_BLOCKING;
94 else if (held_rw == BTRFS_READ_LOCK)
95 held_rw = BTRFS_READ_LOCK_BLOCKING;
96 }
97 btrfs_set_path_blocking(p);
98#endif
99
100 for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
101 if (p->nodes[i] && p->locks[i]) {
102 btrfs_clear_lock_blocking_rw(p->nodes[i], p->locks[i]);
103 if (p->locks[i] == BTRFS_WRITE_LOCK_BLOCKING)
104 p->locks[i] = BTRFS_WRITE_LOCK;
105 else if (p->locks[i] == BTRFS_READ_LOCK_BLOCKING)
106 p->locks[i] = BTRFS_READ_LOCK;
107 }
108 }
109
110#ifdef CONFIG_DEBUG_LOCK_ALLOC
111 if (held)
112 btrfs_clear_lock_blocking_rw(held, held_rw);
113#endif
114}
115
116/* this also releases the path */
117void btrfs_free_path(struct btrfs_path *p)
118{
119 if (!p)
120 return;
121 btrfs_release_path(p);
122 kmem_cache_free(btrfs_path_cachep, p);
123}
124
125/*
126 * path release drops references on the extent buffers in the path
127 * and it drops any locks held by this path
128 *
129 * It is safe to call this on paths that no locks or extent buffers held.
130 */
131noinline void btrfs_release_path(struct btrfs_path *p)
132{
133 int i;
134
135 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
136 p->slots[i] = 0;
137 if (!p->nodes[i])
138 continue;
139 if (p->locks[i]) {
140 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
141 p->locks[i] = 0;
142 }
143 free_extent_buffer(p->nodes[i]);
144 p->nodes[i] = NULL;
145 }
146}
147
148/*
149 * safely gets a reference on the root node of a tree. A lock
150 * is not taken, so a concurrent writer may put a different node
151 * at the root of the tree. See btrfs_lock_root_node for the
152 * looping required.
153 *
154 * The extent buffer returned by this has a reference taken, so
155 * it won't disappear. It may stop being the root of the tree
156 * at any time because there are no locks held.
157 */
158struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
159{
160 struct extent_buffer *eb;
161
162 while (1) {
163 rcu_read_lock();
164 eb = rcu_dereference(root->node);
165
166 /*
167 * RCU really hurts here, we could free up the root node because
168 * it was cow'ed but we may not get the new root node yet so do
169 * the inc_not_zero dance and if it doesn't work then
170 * synchronize_rcu and try again.
171 */
172 if (atomic_inc_not_zero(&eb->refs)) {
173 rcu_read_unlock();
174 break;
175 }
176 rcu_read_unlock();
177 synchronize_rcu();
178 }
179 return eb;
180}
181
182/* loop around taking references on and locking the root node of the
183 * tree until you end up with a lock on the root. A locked buffer
184 * is returned, with a reference held.
185 */
186struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
187{
188 struct extent_buffer *eb;
189
190 while (1) {
191 eb = btrfs_root_node(root);
192 btrfs_tree_lock(eb);
193 if (eb == root->node)
194 break;
195 btrfs_tree_unlock(eb);
196 free_extent_buffer(eb);
197 }
198 return eb;
199}
200
201/* loop around taking references on and locking the root node of the
202 * tree until you end up with a lock on the root. A locked buffer
203 * is returned, with a reference held.
204 */
205static struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
206{
207 struct extent_buffer *eb;
208
209 while (1) {
210 eb = btrfs_root_node(root);
211 btrfs_tree_read_lock(eb);
212 if (eb == root->node)
213 break;
214 btrfs_tree_read_unlock(eb);
215 free_extent_buffer(eb);
216 }
217 return eb;
218}
219
220/* cowonly root (everything not a reference counted cow subvolume), just get
221 * put onto a simple dirty list. transaction.c walks this to make sure they
222 * get properly updated on disk.
223 */
224static void add_root_to_dirty_list(struct btrfs_root *root)
225{
226 spin_lock(&root->fs_info->trans_lock);
227 if (root->track_dirty && list_empty(&root->dirty_list)) {
228 list_add(&root->dirty_list,
229 &root->fs_info->dirty_cowonly_roots);
230 }
231 spin_unlock(&root->fs_info->trans_lock);
232}
233
234/*
235 * used by snapshot creation to make a copy of a root for a tree with
236 * a given objectid. The buffer with the new root node is returned in
237 * cow_ret, and this func returns zero on success or a negative error code.
238 */
239int btrfs_copy_root(struct btrfs_trans_handle *trans,
240 struct btrfs_root *root,
241 struct extent_buffer *buf,
242 struct extent_buffer **cow_ret, u64 new_root_objectid)
243{
244 struct extent_buffer *cow;
245 int ret = 0;
246 int level;
247 struct btrfs_disk_key disk_key;
248
249 WARN_ON(root->ref_cows && trans->transid !=
250 root->fs_info->running_transaction->transid);
251 WARN_ON(root->ref_cows && trans->transid != root->last_trans);
252
253 level = btrfs_header_level(buf);
254 if (level == 0)
255 btrfs_item_key(buf, &disk_key, 0);
256 else
257 btrfs_node_key(buf, &disk_key, 0);
258
259 cow = btrfs_alloc_free_block(trans, root, buf->len, 0,
260 new_root_objectid, &disk_key, level,
261 buf->start, 0);
262 if (IS_ERR(cow))
263 return PTR_ERR(cow);
264
265 copy_extent_buffer(cow, buf, 0, 0, cow->len);
266 btrfs_set_header_bytenr(cow, cow->start);
267 btrfs_set_header_generation(cow, trans->transid);
268 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
269 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
270 BTRFS_HEADER_FLAG_RELOC);
271 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
272 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
273 else
274 btrfs_set_header_owner(cow, new_root_objectid);
275
276 write_extent_buffer(cow, root->fs_info->fsid, btrfs_header_fsid(),
277 BTRFS_FSID_SIZE);
278
279 WARN_ON(btrfs_header_generation(buf) > trans->transid);
280 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
281 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
282 else
283 ret = btrfs_inc_ref(trans, root, cow, 0, 1);
284
285 if (ret)
286 return ret;
287
288 btrfs_mark_buffer_dirty(cow);
289 *cow_ret = cow;
290 return 0;
291}
292
293enum mod_log_op {
294 MOD_LOG_KEY_REPLACE,
295 MOD_LOG_KEY_ADD,
296 MOD_LOG_KEY_REMOVE,
297 MOD_LOG_KEY_REMOVE_WHILE_FREEING,
298 MOD_LOG_KEY_REMOVE_WHILE_MOVING,
299 MOD_LOG_MOVE_KEYS,
300 MOD_LOG_ROOT_REPLACE,
301};
302
303struct tree_mod_move {
304 int dst_slot;
305 int nr_items;
306};
307
308struct tree_mod_root {
309 u64 logical;
310 u8 level;
311};
312
313struct tree_mod_elem {
314 struct rb_node node;
315 u64 index; /* shifted logical */
316 u64 seq;
317 enum mod_log_op op;
318
319 /* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
320 int slot;
321
322 /* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
323 u64 generation;
324
325 /* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
326 struct btrfs_disk_key key;
327 u64 blockptr;
328
329 /* this is used for op == MOD_LOG_MOVE_KEYS */
330 struct tree_mod_move move;
331
332 /* this is used for op == MOD_LOG_ROOT_REPLACE */
333 struct tree_mod_root old_root;
334};
335
336static inline void tree_mod_log_read_lock(struct btrfs_fs_info *fs_info)
337{
338 read_lock(&fs_info->tree_mod_log_lock);
339}
340
341static inline void tree_mod_log_read_unlock(struct btrfs_fs_info *fs_info)
342{
343 read_unlock(&fs_info->tree_mod_log_lock);
344}
345
346static inline void tree_mod_log_write_lock(struct btrfs_fs_info *fs_info)
347{
348 write_lock(&fs_info->tree_mod_log_lock);
349}
350
351static inline void tree_mod_log_write_unlock(struct btrfs_fs_info *fs_info)
352{
353 write_unlock(&fs_info->tree_mod_log_lock);
354}
355
356/*
357 * Increment the upper half of tree_mod_seq, set lower half zero.
358 *
359 * Must be called with fs_info->tree_mod_seq_lock held.
360 */
361static inline u64 btrfs_inc_tree_mod_seq_major(struct btrfs_fs_info *fs_info)
362{
363 u64 seq = atomic64_read(&fs_info->tree_mod_seq);
364 seq &= 0xffffffff00000000ull;
365 seq += 1ull << 32;
366 atomic64_set(&fs_info->tree_mod_seq, seq);
367 return seq;
368}
369
370/*
371 * Increment the lower half of tree_mod_seq.
372 *
373 * Must be called with fs_info->tree_mod_seq_lock held. The way major numbers
374 * are generated should not technically require a spin lock here. (Rationale:
375 * incrementing the minor while incrementing the major seq number is between its
376 * atomic64_read and atomic64_set calls doesn't duplicate sequence numbers, it
377 * just returns a unique sequence number as usual.) We have decided to leave
378 * that requirement in here and rethink it once we notice it really imposes a
379 * problem on some workload.
380 */
381static inline u64 btrfs_inc_tree_mod_seq_minor(struct btrfs_fs_info *fs_info)
382{
383 return atomic64_inc_return(&fs_info->tree_mod_seq);
384}
385
386/*
387 * return the last minor in the previous major tree_mod_seq number
388 */
389u64 btrfs_tree_mod_seq_prev(u64 seq)
390{
391 return (seq & 0xffffffff00000000ull) - 1ull;
392}
393
394/*
395 * This adds a new blocker to the tree mod log's blocker list if the @elem
396 * passed does not already have a sequence number set. So when a caller expects
397 * to record tree modifications, it should ensure to set elem->seq to zero
398 * before calling btrfs_get_tree_mod_seq.
399 * Returns a fresh, unused tree log modification sequence number, even if no new
400 * blocker was added.
401 */
402u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
403 struct seq_list *elem)
404{
405 u64 seq;
406
407 tree_mod_log_write_lock(fs_info);
408 spin_lock(&fs_info->tree_mod_seq_lock);
409 if (!elem->seq) {
410 elem->seq = btrfs_inc_tree_mod_seq_major(fs_info);
411 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
412 }
413 seq = btrfs_inc_tree_mod_seq_minor(fs_info);
414 spin_unlock(&fs_info->tree_mod_seq_lock);
415 tree_mod_log_write_unlock(fs_info);
416
417 return seq;
418}
419
420void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
421 struct seq_list *elem)
422{
423 struct rb_root *tm_root;
424 struct rb_node *node;
425 struct rb_node *next;
426 struct seq_list *cur_elem;
427 struct tree_mod_elem *tm;
428 u64 min_seq = (u64)-1;
429 u64 seq_putting = elem->seq;
430
431 if (!seq_putting)
432 return;
433
434 spin_lock(&fs_info->tree_mod_seq_lock);
435 list_del(&elem->list);
436 elem->seq = 0;
437
438 list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) {
439 if (cur_elem->seq < min_seq) {
440 if (seq_putting > cur_elem->seq) {
441 /*
442 * blocker with lower sequence number exists, we
443 * cannot remove anything from the log
444 */
445 spin_unlock(&fs_info->tree_mod_seq_lock);
446 return;
447 }
448 min_seq = cur_elem->seq;
449 }
450 }
451 spin_unlock(&fs_info->tree_mod_seq_lock);
452
453 /*
454 * anything that's lower than the lowest existing (read: blocked)
455 * sequence number can be removed from the tree.
456 */
457 tree_mod_log_write_lock(fs_info);
458 tm_root = &fs_info->tree_mod_log;
459 for (node = rb_first(tm_root); node; node = next) {
460 next = rb_next(node);
461 tm = container_of(node, struct tree_mod_elem, node);
462 if (tm->seq > min_seq)
463 continue;
464 rb_erase(node, tm_root);
465 kfree(tm);
466 }
467 tree_mod_log_write_unlock(fs_info);
468}
469
470/*
471 * key order of the log:
472 * index -> sequence
473 *
474 * the index is the shifted logical of the *new* root node for root replace
475 * operations, or the shifted logical of the affected block for all other
476 * operations.
477 *
478 * Note: must be called with write lock (tree_mod_log_write_lock).
479 */
480static noinline int
481__tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
482{
483 struct rb_root *tm_root;
484 struct rb_node **new;
485 struct rb_node *parent = NULL;
486 struct tree_mod_elem *cur;
487
488 BUG_ON(!tm);
489
490 spin_lock(&fs_info->tree_mod_seq_lock);
491 tm->seq = btrfs_inc_tree_mod_seq_minor(fs_info);
492 spin_unlock(&fs_info->tree_mod_seq_lock);
493
494 tm_root = &fs_info->tree_mod_log;
495 new = &tm_root->rb_node;
496 while (*new) {
497 cur = container_of(*new, struct tree_mod_elem, node);
498 parent = *new;
499 if (cur->index < tm->index)
500 new = &((*new)->rb_left);
501 else if (cur->index > tm->index)
502 new = &((*new)->rb_right);
503 else if (cur->seq < tm->seq)
504 new = &((*new)->rb_left);
505 else if (cur->seq > tm->seq)
506 new = &((*new)->rb_right);
507 else
508 return -EEXIST;
509 }
510
511 rb_link_node(&tm->node, parent, new);
512 rb_insert_color(&tm->node, tm_root);
513 return 0;
514}
515
516/*
517 * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it
518 * returns zero with the tree_mod_log_lock acquired. The caller must hold
519 * this until all tree mod log insertions are recorded in the rb tree and then
520 * call tree_mod_log_write_unlock() to release.
521 */
522static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
523 struct extent_buffer *eb) {
524 smp_mb();
525 if (list_empty(&(fs_info)->tree_mod_seq_list))
526 return 1;
527 if (eb && btrfs_header_level(eb) == 0)
528 return 1;
529
530 tree_mod_log_write_lock(fs_info);
531 if (list_empty(&(fs_info)->tree_mod_seq_list)) {
532 tree_mod_log_write_unlock(fs_info);
533 return 1;
534 }
535
536 return 0;
537}
538
539/* Similar to tree_mod_dont_log, but doesn't acquire any locks. */
540static inline int tree_mod_need_log(const struct btrfs_fs_info *fs_info,
541 struct extent_buffer *eb)
542{
543 smp_mb();
544 if (list_empty(&(fs_info)->tree_mod_seq_list))
545 return 0;
546 if (eb && btrfs_header_level(eb) == 0)
547 return 0;
548
549 return 1;
550}
551
552static struct tree_mod_elem *
553alloc_tree_mod_elem(struct extent_buffer *eb, int slot,
554 enum mod_log_op op, gfp_t flags)
555{
556 struct tree_mod_elem *tm;
557
558 tm = kzalloc(sizeof(*tm), flags);
559 if (!tm)
560 return NULL;
561
562 tm->index = eb->start >> PAGE_CACHE_SHIFT;
563 if (op != MOD_LOG_KEY_ADD) {
564 btrfs_node_key(eb, &tm->key, slot);
565 tm->blockptr = btrfs_node_blockptr(eb, slot);
566 }
567 tm->op = op;
568 tm->slot = slot;
569 tm->generation = btrfs_node_ptr_generation(eb, slot);
570 RB_CLEAR_NODE(&tm->node);
571
572 return tm;
573}
574
575static noinline int
576tree_mod_log_insert_key(struct btrfs_fs_info *fs_info,
577 struct extent_buffer *eb, int slot,
578 enum mod_log_op op, gfp_t flags)
579{
580 struct tree_mod_elem *tm;
581 int ret;
582
583 if (!tree_mod_need_log(fs_info, eb))
584 return 0;
585
586 tm = alloc_tree_mod_elem(eb, slot, op, flags);
587 if (!tm)
588 return -ENOMEM;
589
590 if (tree_mod_dont_log(fs_info, eb)) {
591 kfree(tm);
592 return 0;
593 }
594
595 ret = __tree_mod_log_insert(fs_info, tm);
596 tree_mod_log_write_unlock(fs_info);
597 if (ret)
598 kfree(tm);
599
600 return ret;
601}
602
603static noinline int
604tree_mod_log_insert_move(struct btrfs_fs_info *fs_info,
605 struct extent_buffer *eb, int dst_slot, int src_slot,
606 int nr_items, gfp_t flags)
607{
608 struct tree_mod_elem *tm = NULL;
609 struct tree_mod_elem **tm_list = NULL;
610 int ret = 0;
611 int i;
612 int locked = 0;
613
614 if (!tree_mod_need_log(fs_info, eb))
615 return 0;
616
617 tm_list = kzalloc(nr_items * sizeof(struct tree_mod_elem *), flags);
618 if (!tm_list)
619 return -ENOMEM;
620
621 tm = kzalloc(sizeof(*tm), flags);
622 if (!tm) {
623 ret = -ENOMEM;
624 goto free_tms;
625 }
626
627 tm->index = eb->start >> PAGE_CACHE_SHIFT;
628 tm->slot = src_slot;
629 tm->move.dst_slot = dst_slot;
630 tm->move.nr_items = nr_items;
631 tm->op = MOD_LOG_MOVE_KEYS;
632
633 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
634 tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot,
635 MOD_LOG_KEY_REMOVE_WHILE_MOVING, flags);
636 if (!tm_list[i]) {
637 ret = -ENOMEM;
638 goto free_tms;
639 }
640 }
641
642 if (tree_mod_dont_log(fs_info, eb))
643 goto free_tms;
644 locked = 1;
645
646 /*
647 * When we override something during the move, we log these removals.
648 * This can only happen when we move towards the beginning of the
649 * buffer, i.e. dst_slot < src_slot.
650 */
651 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
652 ret = __tree_mod_log_insert(fs_info, tm_list[i]);
653 if (ret)
654 goto free_tms;
655 }
656
657 ret = __tree_mod_log_insert(fs_info, tm);
658 if (ret)
659 goto free_tms;
660 tree_mod_log_write_unlock(fs_info);
661 kfree(tm_list);
662
663 return 0;
664free_tms:
665 for (i = 0; i < nr_items; i++) {
666 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
667 rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
668 kfree(tm_list[i]);
669 }
670 if (locked)
671 tree_mod_log_write_unlock(fs_info);
672 kfree(tm_list);
673 kfree(tm);
674
675 return ret;
676}
677
678static inline int
679__tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
680 struct tree_mod_elem **tm_list,
681 int nritems)
682{
683 int i, j;
684 int ret;
685
686 for (i = nritems - 1; i >= 0; i--) {
687 ret = __tree_mod_log_insert(fs_info, tm_list[i]);
688 if (ret) {
689 for (j = nritems - 1; j > i; j--)
690 rb_erase(&tm_list[j]->node,
691 &fs_info->tree_mod_log);
692 return ret;
693 }
694 }
695
696 return 0;
697}
698
699static noinline int
700tree_mod_log_insert_root(struct btrfs_fs_info *fs_info,
701 struct extent_buffer *old_root,
702 struct extent_buffer *new_root, gfp_t flags,
703 int log_removal)
704{
705 struct tree_mod_elem *tm = NULL;
706 struct tree_mod_elem **tm_list = NULL;
707 int nritems = 0;
708 int ret = 0;
709 int i;
710
711 if (!tree_mod_need_log(fs_info, NULL))
712 return 0;
713
714 if (log_removal && btrfs_header_level(old_root) > 0) {
715 nritems = btrfs_header_nritems(old_root);
716 tm_list = kzalloc(nritems * sizeof(struct tree_mod_elem *),
717 flags);
718 if (!tm_list) {
719 ret = -ENOMEM;
720 goto free_tms;
721 }
722 for (i = 0; i < nritems; i++) {
723 tm_list[i] = alloc_tree_mod_elem(old_root, i,
724 MOD_LOG_KEY_REMOVE_WHILE_FREEING, flags);
725 if (!tm_list[i]) {
726 ret = -ENOMEM;
727 goto free_tms;
728 }
729 }
730 }
731
732 tm = kzalloc(sizeof(*tm), flags);
733 if (!tm) {
734 ret = -ENOMEM;
735 goto free_tms;
736 }
737
738 tm->index = new_root->start >> PAGE_CACHE_SHIFT;
739 tm->old_root.logical = old_root->start;
740 tm->old_root.level = btrfs_header_level(old_root);
741 tm->generation = btrfs_header_generation(old_root);
742 tm->op = MOD_LOG_ROOT_REPLACE;
743
744 if (tree_mod_dont_log(fs_info, NULL))
745 goto free_tms;
746
747 if (tm_list)
748 ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
749 if (!ret)
750 ret = __tree_mod_log_insert(fs_info, tm);
751
752 tree_mod_log_write_unlock(fs_info);
753 if (ret)
754 goto free_tms;
755 kfree(tm_list);
756
757 return ret;
758
759free_tms:
760 if (tm_list) {
761 for (i = 0; i < nritems; i++)
762 kfree(tm_list[i]);
763 kfree(tm_list);
764 }
765 kfree(tm);
766
767 return ret;
768}
769
770static struct tree_mod_elem *
771__tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
772 int smallest)
773{
774 struct rb_root *tm_root;
775 struct rb_node *node;
776 struct tree_mod_elem *cur = NULL;
777 struct tree_mod_elem *found = NULL;
778 u64 index = start >> PAGE_CACHE_SHIFT;
779
780 tree_mod_log_read_lock(fs_info);
781 tm_root = &fs_info->tree_mod_log;
782 node = tm_root->rb_node;
783 while (node) {
784 cur = container_of(node, struct tree_mod_elem, node);
785 if (cur->index < index) {
786 node = node->rb_left;
787 } else if (cur->index > index) {
788 node = node->rb_right;
789 } else if (cur->seq < min_seq) {
790 node = node->rb_left;
791 } else if (!smallest) {
792 /* we want the node with the highest seq */
793 if (found)
794 BUG_ON(found->seq > cur->seq);
795 found = cur;
796 node = node->rb_left;
797 } else if (cur->seq > min_seq) {
798 /* we want the node with the smallest seq */
799 if (found)
800 BUG_ON(found->seq < cur->seq);
801 found = cur;
802 node = node->rb_right;
803 } else {
804 found = cur;
805 break;
806 }
807 }
808 tree_mod_log_read_unlock(fs_info);
809
810 return found;
811}
812
813/*
814 * this returns the element from the log with the smallest time sequence
815 * value that's in the log (the oldest log item). any element with a time
816 * sequence lower than min_seq will be ignored.
817 */
818static struct tree_mod_elem *
819tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
820 u64 min_seq)
821{
822 return __tree_mod_log_search(fs_info, start, min_seq, 1);
823}
824
825/*
826 * this returns the element from the log with the largest time sequence
827 * value that's in the log (the most recent log item). any element with
828 * a time sequence lower than min_seq will be ignored.
829 */
830static struct tree_mod_elem *
831tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
832{
833 return __tree_mod_log_search(fs_info, start, min_seq, 0);
834}
835
836static noinline int
837tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
838 struct extent_buffer *src, unsigned long dst_offset,
839 unsigned long src_offset, int nr_items)
840{
841 int ret = 0;
842 struct tree_mod_elem **tm_list = NULL;
843 struct tree_mod_elem **tm_list_add, **tm_list_rem;
844 int i;
845 int locked = 0;
846
847 if (!tree_mod_need_log(fs_info, NULL))
848 return 0;
849
850 if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
851 return 0;
852
853 tm_list = kzalloc(nr_items * 2 * sizeof(struct tree_mod_elem *),
854 GFP_NOFS);
855 if (!tm_list)
856 return -ENOMEM;
857
858 tm_list_add = tm_list;
859 tm_list_rem = tm_list + nr_items;
860 for (i = 0; i < nr_items; i++) {
861 tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset,
862 MOD_LOG_KEY_REMOVE, GFP_NOFS);
863 if (!tm_list_rem[i]) {
864 ret = -ENOMEM;
865 goto free_tms;
866 }
867
868 tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset,
869 MOD_LOG_KEY_ADD, GFP_NOFS);
870 if (!tm_list_add[i]) {
871 ret = -ENOMEM;
872 goto free_tms;
873 }
874 }
875
876 if (tree_mod_dont_log(fs_info, NULL))
877 goto free_tms;
878 locked = 1;
879
880 for (i = 0; i < nr_items; i++) {
881 ret = __tree_mod_log_insert(fs_info, tm_list_rem[i]);
882 if (ret)
883 goto free_tms;
884 ret = __tree_mod_log_insert(fs_info, tm_list_add[i]);
885 if (ret)
886 goto free_tms;
887 }
888
889 tree_mod_log_write_unlock(fs_info);
890 kfree(tm_list);
891
892 return 0;
893
894free_tms:
895 for (i = 0; i < nr_items * 2; i++) {
896 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
897 rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
898 kfree(tm_list[i]);
899 }
900 if (locked)
901 tree_mod_log_write_unlock(fs_info);
902 kfree(tm_list);
903
904 return ret;
905}
906
907static inline void
908tree_mod_log_eb_move(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
909 int dst_offset, int src_offset, int nr_items)
910{
911 int ret;
912 ret = tree_mod_log_insert_move(fs_info, dst, dst_offset, src_offset,
913 nr_items, GFP_NOFS);
914 BUG_ON(ret < 0);
915}
916
917static noinline void
918tree_mod_log_set_node_key(struct btrfs_fs_info *fs_info,
919 struct extent_buffer *eb, int slot, int atomic)
920{
921 int ret;
922
923 ret = tree_mod_log_insert_key(fs_info, eb, slot,
924 MOD_LOG_KEY_REPLACE,
925 atomic ? GFP_ATOMIC : GFP_NOFS);
926 BUG_ON(ret < 0);
927}
928
929static noinline int
930tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, struct extent_buffer *eb)
931{
932 struct tree_mod_elem **tm_list = NULL;
933 int nritems = 0;
934 int i;
935 int ret = 0;
936
937 if (btrfs_header_level(eb) == 0)
938 return 0;
939
940 if (!tree_mod_need_log(fs_info, NULL))
941 return 0;
942
943 nritems = btrfs_header_nritems(eb);
944 tm_list = kzalloc(nritems * sizeof(struct tree_mod_elem *),
945 GFP_NOFS);
946 if (!tm_list)
947 return -ENOMEM;
948
949 for (i = 0; i < nritems; i++) {
950 tm_list[i] = alloc_tree_mod_elem(eb, i,
951 MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
952 if (!tm_list[i]) {
953 ret = -ENOMEM;
954 goto free_tms;
955 }
956 }
957
958 if (tree_mod_dont_log(fs_info, eb))
959 goto free_tms;
960
961 ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
962 tree_mod_log_write_unlock(fs_info);
963 if (ret)
964 goto free_tms;
965 kfree(tm_list);
966
967 return 0;
968
969free_tms:
970 for (i = 0; i < nritems; i++)
971 kfree(tm_list[i]);
972 kfree(tm_list);
973
974 return ret;
975}
976
977static noinline void
978tree_mod_log_set_root_pointer(struct btrfs_root *root,
979 struct extent_buffer *new_root_node,
980 int log_removal)
981{
982 int ret;
983 ret = tree_mod_log_insert_root(root->fs_info, root->node,
984 new_root_node, GFP_NOFS, log_removal);
985 BUG_ON(ret < 0);
986}
987
988/*
989 * check if the tree block can be shared by multiple trees
990 */
991int btrfs_block_can_be_shared(struct btrfs_root *root,
992 struct extent_buffer *buf)
993{
994 /*
995 * Tree blocks not in refernece counted trees and tree roots
996 * are never shared. If a block was allocated after the last
997 * snapshot and the block was not allocated by tree relocation,
998 * we know the block is not shared.
999 */
1000 if (root->ref_cows &&
1001 buf != root->node && buf != root->commit_root &&
1002 (btrfs_header_generation(buf) <=
1003 btrfs_root_last_snapshot(&root->root_item) ||
1004 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
1005 return 1;
1006#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
1007 if (root->ref_cows &&
1008 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1009 return 1;
1010#endif
1011 return 0;
1012}
1013
1014static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
1015 struct btrfs_root *root,
1016 struct extent_buffer *buf,
1017 struct extent_buffer *cow,
1018 int *last_ref)
1019{
1020 u64 refs;
1021 u64 owner;
1022 u64 flags;
1023 u64 new_flags = 0;
1024 int ret;
1025
1026 /*
1027 * Backrefs update rules:
1028 *
1029 * Always use full backrefs for extent pointers in tree block
1030 * allocated by tree relocation.
1031 *
1032 * If a shared tree block is no longer referenced by its owner
1033 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
1034 * use full backrefs for extent pointers in tree block.
1035 *
1036 * If a tree block is been relocating
1037 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
1038 * use full backrefs for extent pointers in tree block.
1039 * The reason for this is some operations (such as drop tree)
1040 * are only allowed for blocks use full backrefs.
1041 */
1042
1043 if (btrfs_block_can_be_shared(root, buf)) {
1044 ret = btrfs_lookup_extent_info(trans, root, buf->start,
1045 btrfs_header_level(buf), 1,
1046 &refs, &flags);
1047 if (ret)
1048 return ret;
1049 if (refs == 0) {
1050 ret = -EROFS;
1051 btrfs_std_error(root->fs_info, ret);
1052 return ret;
1053 }
1054 } else {
1055 refs = 1;
1056 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1057 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1058 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
1059 else
1060 flags = 0;
1061 }
1062
1063 owner = btrfs_header_owner(buf);
1064 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
1065 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
1066
1067 if (refs > 1) {
1068 if ((owner == root->root_key.objectid ||
1069 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
1070 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
1071 ret = btrfs_inc_ref(trans, root, buf, 1, 1);
1072 BUG_ON(ret); /* -ENOMEM */
1073
1074 if (root->root_key.objectid ==
1075 BTRFS_TREE_RELOC_OBJECTID) {
1076 ret = btrfs_dec_ref(trans, root, buf, 0, 1);
1077 BUG_ON(ret); /* -ENOMEM */
1078 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
1079 BUG_ON(ret); /* -ENOMEM */
1080 }
1081 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
1082 } else {
1083
1084 if (root->root_key.objectid ==
1085 BTRFS_TREE_RELOC_OBJECTID)
1086 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
1087 else
1088 ret = btrfs_inc_ref(trans, root, cow, 0, 1);
1089 BUG_ON(ret); /* -ENOMEM */
1090 }
1091 if (new_flags != 0) {
1092 int level = btrfs_header_level(buf);
1093
1094 ret = btrfs_set_disk_extent_flags(trans, root,
1095 buf->start,
1096 buf->len,
1097 new_flags, level, 0);
1098 if (ret)
1099 return ret;
1100 }
1101 } else {
1102 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
1103 if (root->root_key.objectid ==
1104 BTRFS_TREE_RELOC_OBJECTID)
1105 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
1106 else
1107 ret = btrfs_inc_ref(trans, root, cow, 0, 1);
1108 BUG_ON(ret); /* -ENOMEM */
1109 ret = btrfs_dec_ref(trans, root, buf, 1, 1);
1110 BUG_ON(ret); /* -ENOMEM */
1111 }
1112 clean_tree_block(trans, root, buf);
1113 *last_ref = 1;
1114 }
1115 return 0;
1116}
1117
1118/*
1119 * does the dirty work in cow of a single block. The parent block (if
1120 * supplied) is updated to point to the new cow copy. The new buffer is marked
1121 * dirty and returned locked. If you modify the block it needs to be marked
1122 * dirty again.
1123 *
1124 * search_start -- an allocation hint for the new block
1125 *
1126 * empty_size -- a hint that you plan on doing more cow. This is the size in
1127 * bytes the allocator should try to find free next to the block it returns.
1128 * This is just a hint and may be ignored by the allocator.
1129 */
1130static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
1131 struct btrfs_root *root,
1132 struct extent_buffer *buf,
1133 struct extent_buffer *parent, int parent_slot,
1134 struct extent_buffer **cow_ret,
1135 u64 search_start, u64 empty_size)
1136{
1137 struct btrfs_disk_key disk_key;
1138 struct extent_buffer *cow;
1139 int level, ret;
1140 int last_ref = 0;
1141 int unlock_orig = 0;
1142 u64 parent_start;
1143
1144 if (*cow_ret == buf)
1145 unlock_orig = 1;
1146
1147 btrfs_assert_tree_locked(buf);
1148
1149 WARN_ON(root->ref_cows && trans->transid !=
1150 root->fs_info->running_transaction->transid);
1151 WARN_ON(root->ref_cows && trans->transid != root->last_trans);
1152
1153 level = btrfs_header_level(buf);
1154
1155 if (level == 0)
1156 btrfs_item_key(buf, &disk_key, 0);
1157 else
1158 btrfs_node_key(buf, &disk_key, 0);
1159
1160 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
1161 if (parent)
1162 parent_start = parent->start;
1163 else
1164 parent_start = 0;
1165 } else
1166 parent_start = 0;
1167
1168 cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start,
1169 root->root_key.objectid, &disk_key,
1170 level, search_start, empty_size);
1171 if (IS_ERR(cow))
1172 return PTR_ERR(cow);
1173
1174 /* cow is set to blocking by btrfs_init_new_buffer */
1175
1176 copy_extent_buffer(cow, buf, 0, 0, cow->len);
1177 btrfs_set_header_bytenr(cow, cow->start);
1178 btrfs_set_header_generation(cow, trans->transid);
1179 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
1180 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
1181 BTRFS_HEADER_FLAG_RELOC);
1182 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1183 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
1184 else
1185 btrfs_set_header_owner(cow, root->root_key.objectid);
1186
1187 write_extent_buffer(cow, root->fs_info->fsid, btrfs_header_fsid(),
1188 BTRFS_FSID_SIZE);
1189
1190 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
1191 if (ret) {
1192 btrfs_abort_transaction(trans, root, ret);
1193 return ret;
1194 }
1195
1196 if (root->ref_cows) {
1197 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
1198 if (ret)
1199 return ret;
1200 }
1201
1202 if (buf == root->node) {
1203 WARN_ON(parent && parent != buf);
1204 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1205 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1206 parent_start = buf->start;
1207 else
1208 parent_start = 0;
1209
1210 extent_buffer_get(cow);
1211 tree_mod_log_set_root_pointer(root, cow, 1);
1212 rcu_assign_pointer(root->node, cow);
1213
1214 btrfs_free_tree_block(trans, root, buf, parent_start,
1215 last_ref);
1216 free_extent_buffer(buf);
1217 add_root_to_dirty_list(root);
1218 } else {
1219 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1220 parent_start = parent->start;
1221 else
1222 parent_start = 0;
1223
1224 WARN_ON(trans->transid != btrfs_header_generation(parent));
1225 tree_mod_log_insert_key(root->fs_info, parent, parent_slot,
1226 MOD_LOG_KEY_REPLACE, GFP_NOFS);
1227 btrfs_set_node_blockptr(parent, parent_slot,
1228 cow->start);
1229 btrfs_set_node_ptr_generation(parent, parent_slot,
1230 trans->transid);
1231 btrfs_mark_buffer_dirty(parent);
1232 if (last_ref) {
1233 ret = tree_mod_log_free_eb(root->fs_info, buf);
1234 if (ret) {
1235 btrfs_abort_transaction(trans, root, ret);
1236 return ret;
1237 }
1238 }
1239 btrfs_free_tree_block(trans, root, buf, parent_start,
1240 last_ref);
1241 }
1242 if (unlock_orig)
1243 btrfs_tree_unlock(buf);
1244 free_extent_buffer_stale(buf);
1245 btrfs_mark_buffer_dirty(cow);
1246 *cow_ret = cow;
1247 return 0;
1248}
1249
1250/*
1251 * returns the logical address of the oldest predecessor of the given root.
1252 * entries older than time_seq are ignored.
1253 */
1254static struct tree_mod_elem *
1255__tree_mod_log_oldest_root(struct btrfs_fs_info *fs_info,
1256 struct extent_buffer *eb_root, u64 time_seq)
1257{
1258 struct tree_mod_elem *tm;
1259 struct tree_mod_elem *found = NULL;
1260 u64 root_logical = eb_root->start;
1261 int looped = 0;
1262
1263 if (!time_seq)
1264 return NULL;
1265
1266 /*
1267 * the very last operation that's logged for a root is the replacement
1268 * operation (if it is replaced at all). this has the index of the *new*
1269 * root, making it the very first operation that's logged for this root.
1270 */
1271 while (1) {
1272 tm = tree_mod_log_search_oldest(fs_info, root_logical,
1273 time_seq);
1274 if (!looped && !tm)
1275 return NULL;
1276 /*
1277 * if there are no tree operation for the oldest root, we simply
1278 * return it. this should only happen if that (old) root is at
1279 * level 0.
1280 */
1281 if (!tm)
1282 break;
1283
1284 /*
1285 * if there's an operation that's not a root replacement, we
1286 * found the oldest version of our root. normally, we'll find a
1287 * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1288 */
1289 if (tm->op != MOD_LOG_ROOT_REPLACE)
1290 break;
1291
1292 found = tm;
1293 root_logical = tm->old_root.logical;
1294 looped = 1;
1295 }
1296
1297 /* if there's no old root to return, return what we found instead */
1298 if (!found)
1299 found = tm;
1300
1301 return found;
1302}
1303
1304/*
1305 * tm is a pointer to the first operation to rewind within eb. then, all
1306 * previous operations will be rewinded (until we reach something older than
1307 * time_seq).
1308 */
1309static void
1310__tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1311 u64 time_seq, struct tree_mod_elem *first_tm)
1312{
1313 u32 n;
1314 struct rb_node *next;
1315 struct tree_mod_elem *tm = first_tm;
1316 unsigned long o_dst;
1317 unsigned long o_src;
1318 unsigned long p_size = sizeof(struct btrfs_key_ptr);
1319
1320 n = btrfs_header_nritems(eb);
1321 tree_mod_log_read_lock(fs_info);
1322 while (tm && tm->seq >= time_seq) {
1323 /*
1324 * all the operations are recorded with the operator used for
1325 * the modification. as we're going backwards, we do the
1326 * opposite of each operation here.
1327 */
1328 switch (tm->op) {
1329 case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1330 BUG_ON(tm->slot < n);
1331 /* Fallthrough */
1332 case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1333 case MOD_LOG_KEY_REMOVE:
1334 btrfs_set_node_key(eb, &tm->key, tm->slot);
1335 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1336 btrfs_set_node_ptr_generation(eb, tm->slot,
1337 tm->generation);
1338 n++;
1339 break;
1340 case MOD_LOG_KEY_REPLACE:
1341 BUG_ON(tm->slot >= n);
1342 btrfs_set_node_key(eb, &tm->key, tm->slot);
1343 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1344 btrfs_set_node_ptr_generation(eb, tm->slot,
1345 tm->generation);
1346 break;
1347 case MOD_LOG_KEY_ADD:
1348 /* if a move operation is needed it's in the log */
1349 n--;
1350 break;
1351 case MOD_LOG_MOVE_KEYS:
1352 o_dst = btrfs_node_key_ptr_offset(tm->slot);
1353 o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1354 memmove_extent_buffer(eb, o_dst, o_src,
1355 tm->move.nr_items * p_size);
1356 break;
1357 case MOD_LOG_ROOT_REPLACE:
1358 /*
1359 * this operation is special. for roots, this must be
1360 * handled explicitly before rewinding.
1361 * for non-roots, this operation may exist if the node
1362 * was a root: root A -> child B; then A gets empty and
1363 * B is promoted to the new root. in the mod log, we'll
1364 * have a root-replace operation for B, a tree block
1365 * that is no root. we simply ignore that operation.
1366 */
1367 break;
1368 }
1369 next = rb_next(&tm->node);
1370 if (!next)
1371 break;
1372 tm = container_of(next, struct tree_mod_elem, node);
1373 if (tm->index != first_tm->index)
1374 break;
1375 }
1376 tree_mod_log_read_unlock(fs_info);
1377 btrfs_set_header_nritems(eb, n);
1378}
1379
1380/*
1381 * Called with eb read locked. If the buffer cannot be rewinded, the same buffer
1382 * is returned. If rewind operations happen, a fresh buffer is returned. The
1383 * returned buffer is always read-locked. If the returned buffer is not the
1384 * input buffer, the lock on the input buffer is released and the input buffer
1385 * is freed (its refcount is decremented).
1386 */
1387static struct extent_buffer *
1388tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
1389 struct extent_buffer *eb, u64 time_seq)
1390{
1391 struct extent_buffer *eb_rewin;
1392 struct tree_mod_elem *tm;
1393
1394 if (!time_seq)
1395 return eb;
1396
1397 if (btrfs_header_level(eb) == 0)
1398 return eb;
1399
1400 tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1401 if (!tm)
1402 return eb;
1403
1404 btrfs_set_path_blocking(path);
1405 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1406
1407 if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1408 BUG_ON(tm->slot != 0);
1409 eb_rewin = alloc_dummy_extent_buffer(eb->start,
1410 fs_info->tree_root->nodesize);
1411 if (!eb_rewin) {
1412 btrfs_tree_read_unlock_blocking(eb);
1413 free_extent_buffer(eb);
1414 return NULL;
1415 }
1416 btrfs_set_header_bytenr(eb_rewin, eb->start);
1417 btrfs_set_header_backref_rev(eb_rewin,
1418 btrfs_header_backref_rev(eb));
1419 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1420 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1421 } else {
1422 eb_rewin = btrfs_clone_extent_buffer(eb);
1423 if (!eb_rewin) {
1424 btrfs_tree_read_unlock_blocking(eb);
1425 free_extent_buffer(eb);
1426 return NULL;
1427 }
1428 }
1429
1430 btrfs_clear_path_blocking(path, NULL, BTRFS_READ_LOCK);
1431 btrfs_tree_read_unlock_blocking(eb);
1432 free_extent_buffer(eb);
1433
1434 extent_buffer_get(eb_rewin);
1435 btrfs_tree_read_lock(eb_rewin);
1436 __tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm);
1437 WARN_ON(btrfs_header_nritems(eb_rewin) >
1438 BTRFS_NODEPTRS_PER_BLOCK(fs_info->tree_root));
1439
1440 return eb_rewin;
1441}
1442
1443/*
1444 * get_old_root() rewinds the state of @root's root node to the given @time_seq
1445 * value. If there are no changes, the current root->root_node is returned. If
1446 * anything changed in between, there's a fresh buffer allocated on which the
1447 * rewind operations are done. In any case, the returned buffer is read locked.
1448 * Returns NULL on error (with no locks held).
1449 */
1450static inline struct extent_buffer *
1451get_old_root(struct btrfs_root *root, u64 time_seq)
1452{
1453 struct tree_mod_elem *tm;
1454 struct extent_buffer *eb = NULL;
1455 struct extent_buffer *eb_root;
1456 struct extent_buffer *old;
1457 struct tree_mod_root *old_root = NULL;
1458 u64 old_generation = 0;
1459 u64 logical;
1460 u32 blocksize;
1461
1462 eb_root = btrfs_read_lock_root_node(root);
1463 tm = __tree_mod_log_oldest_root(root->fs_info, eb_root, time_seq);
1464 if (!tm)
1465 return eb_root;
1466
1467 if (tm->op == MOD_LOG_ROOT_REPLACE) {
1468 old_root = &tm->old_root;
1469 old_generation = tm->generation;
1470 logical = old_root->logical;
1471 } else {
1472 logical = eb_root->start;
1473 }
1474
1475 tm = tree_mod_log_search(root->fs_info, logical, time_seq);
1476 if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1477 btrfs_tree_read_unlock(eb_root);
1478 free_extent_buffer(eb_root);
1479 blocksize = btrfs_level_size(root, old_root->level);
1480 old = read_tree_block(root, logical, blocksize, 0);
1481 if (WARN_ON(!old || !extent_buffer_uptodate(old))) {
1482 free_extent_buffer(old);
1483 btrfs_warn(root->fs_info,
1484 "failed to read tree block %llu from get_old_root", logical);
1485 } else {
1486 eb = btrfs_clone_extent_buffer(old);
1487 free_extent_buffer(old);
1488 }
1489 } else if (old_root) {
1490 btrfs_tree_read_unlock(eb_root);
1491 free_extent_buffer(eb_root);
1492 eb = alloc_dummy_extent_buffer(logical, root->nodesize);
1493 } else {
1494 btrfs_set_lock_blocking_rw(eb_root, BTRFS_READ_LOCK);
1495 eb = btrfs_clone_extent_buffer(eb_root);
1496 btrfs_tree_read_unlock_blocking(eb_root);
1497 free_extent_buffer(eb_root);
1498 }
1499
1500 if (!eb)
1501 return NULL;
1502 extent_buffer_get(eb);
1503 btrfs_tree_read_lock(eb);
1504 if (old_root) {
1505 btrfs_set_header_bytenr(eb, eb->start);
1506 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1507 btrfs_set_header_owner(eb, btrfs_header_owner(eb_root));
1508 btrfs_set_header_level(eb, old_root->level);
1509 btrfs_set_header_generation(eb, old_generation);
1510 }
1511 if (tm)
1512 __tree_mod_log_rewind(root->fs_info, eb, time_seq, tm);
1513 else
1514 WARN_ON(btrfs_header_level(eb) != 0);
1515 WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(root));
1516
1517 return eb;
1518}
1519
1520int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
1521{
1522 struct tree_mod_elem *tm;
1523 int level;
1524 struct extent_buffer *eb_root = btrfs_root_node(root);
1525
1526 tm = __tree_mod_log_oldest_root(root->fs_info, eb_root, time_seq);
1527 if (tm && tm->op == MOD_LOG_ROOT_REPLACE) {
1528 level = tm->old_root.level;
1529 } else {
1530 level = btrfs_header_level(eb_root);
1531 }
1532 free_extent_buffer(eb_root);
1533
1534 return level;
1535}
1536
1537static inline int should_cow_block(struct btrfs_trans_handle *trans,
1538 struct btrfs_root *root,
1539 struct extent_buffer *buf)
1540{
1541 /* ensure we can see the force_cow */
1542 smp_rmb();
1543
1544 /*
1545 * We do not need to cow a block if
1546 * 1) this block is not created or changed in this transaction;
1547 * 2) this block does not belong to TREE_RELOC tree;
1548 * 3) the root is not forced COW.
1549 *
1550 * What is forced COW:
1551 * when we create snapshot during commiting the transaction,
1552 * after we've finished coping src root, we must COW the shared
1553 * block to ensure the metadata consistency.
1554 */
1555 if (btrfs_header_generation(buf) == trans->transid &&
1556 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1557 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1558 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1559 !root->force_cow)
1560 return 0;
1561 return 1;
1562}
1563
1564/*
1565 * cows a single block, see __btrfs_cow_block for the real work.
1566 * This version of it has extra checks so that a block isn't cow'd more than
1567 * once per transaction, as long as it hasn't been written yet
1568 */
1569noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1570 struct btrfs_root *root, struct extent_buffer *buf,
1571 struct extent_buffer *parent, int parent_slot,
1572 struct extent_buffer **cow_ret)
1573{
1574 u64 search_start;
1575 int ret;
1576
1577 if (trans->transaction != root->fs_info->running_transaction)
1578 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1579 trans->transid,
1580 root->fs_info->running_transaction->transid);
1581
1582 if (trans->transid != root->fs_info->generation)
1583 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1584 trans->transid, root->fs_info->generation);
1585
1586 if (!should_cow_block(trans, root, buf)) {
1587 *cow_ret = buf;
1588 return 0;
1589 }
1590
1591 search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
1592
1593 if (parent)
1594 btrfs_set_lock_blocking(parent);
1595 btrfs_set_lock_blocking(buf);
1596
1597 ret = __btrfs_cow_block(trans, root, buf, parent,
1598 parent_slot, cow_ret, search_start, 0);
1599
1600 trace_btrfs_cow_block(root, buf, *cow_ret);
1601
1602 return ret;
1603}
1604
1605/*
1606 * helper function for defrag to decide if two blocks pointed to by a
1607 * node are actually close by
1608 */
1609static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1610{
1611 if (blocknr < other && other - (blocknr + blocksize) < 32768)
1612 return 1;
1613 if (blocknr > other && blocknr - (other + blocksize) < 32768)
1614 return 1;
1615 return 0;
1616}
1617
1618/*
1619 * compare two keys in a memcmp fashion
1620 */
1621static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
1622{
1623 struct btrfs_key k1;
1624
1625 btrfs_disk_key_to_cpu(&k1, disk);
1626
1627 return btrfs_comp_cpu_keys(&k1, k2);
1628}
1629
1630/*
1631 * same as comp_keys only with two btrfs_key's
1632 */
1633int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2)
1634{
1635 if (k1->objectid > k2->objectid)
1636 return 1;
1637 if (k1->objectid < k2->objectid)
1638 return -1;
1639 if (k1->type > k2->type)
1640 return 1;
1641 if (k1->type < k2->type)
1642 return -1;
1643 if (k1->offset > k2->offset)
1644 return 1;
1645 if (k1->offset < k2->offset)
1646 return -1;
1647 return 0;
1648}
1649
1650/*
1651 * this is used by the defrag code to go through all the
1652 * leaves pointed to by a node and reallocate them so that
1653 * disk order is close to key order
1654 */
1655int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1656 struct btrfs_root *root, struct extent_buffer *parent,
1657 int start_slot, u64 *last_ret,
1658 struct btrfs_key *progress)
1659{
1660 struct extent_buffer *cur;
1661 u64 blocknr;
1662 u64 gen;
1663 u64 search_start = *last_ret;
1664 u64 last_block = 0;
1665 u64 other;
1666 u32 parent_nritems;
1667 int end_slot;
1668 int i;
1669 int err = 0;
1670 int parent_level;
1671 int uptodate;
1672 u32 blocksize;
1673 int progress_passed = 0;
1674 struct btrfs_disk_key disk_key;
1675
1676 parent_level = btrfs_header_level(parent);
1677
1678 WARN_ON(trans->transaction != root->fs_info->running_transaction);
1679 WARN_ON(trans->transid != root->fs_info->generation);
1680
1681 parent_nritems = btrfs_header_nritems(parent);
1682 blocksize = btrfs_level_size(root, parent_level - 1);
1683 end_slot = parent_nritems;
1684
1685 if (parent_nritems == 1)
1686 return 0;
1687
1688 btrfs_set_lock_blocking(parent);
1689
1690 for (i = start_slot; i < end_slot; i++) {
1691 int close = 1;
1692
1693 btrfs_node_key(parent, &disk_key, i);
1694 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1695 continue;
1696
1697 progress_passed = 1;
1698 blocknr = btrfs_node_blockptr(parent, i);
1699 gen = btrfs_node_ptr_generation(parent, i);
1700 if (last_block == 0)
1701 last_block = blocknr;
1702
1703 if (i > 0) {
1704 other = btrfs_node_blockptr(parent, i - 1);
1705 close = close_blocks(blocknr, other, blocksize);
1706 }
1707 if (!close && i < end_slot - 2) {
1708 other = btrfs_node_blockptr(parent, i + 1);
1709 close = close_blocks(blocknr, other, blocksize);
1710 }
1711 if (close) {
1712 last_block = blocknr;
1713 continue;
1714 }
1715
1716 cur = btrfs_find_tree_block(root, blocknr, blocksize);
1717 if (cur)
1718 uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1719 else
1720 uptodate = 0;
1721 if (!cur || !uptodate) {
1722 if (!cur) {
1723 cur = read_tree_block(root, blocknr,
1724 blocksize, gen);
1725 if (!cur || !extent_buffer_uptodate(cur)) {
1726 free_extent_buffer(cur);
1727 return -EIO;
1728 }
1729 } else if (!uptodate) {
1730 err = btrfs_read_buffer(cur, gen);
1731 if (err) {
1732 free_extent_buffer(cur);
1733 return err;
1734 }
1735 }
1736 }
1737 if (search_start == 0)
1738 search_start = last_block;
1739
1740 btrfs_tree_lock(cur);
1741 btrfs_set_lock_blocking(cur);
1742 err = __btrfs_cow_block(trans, root, cur, parent, i,
1743 &cur, search_start,
1744 min(16 * blocksize,
1745 (end_slot - i) * blocksize));
1746 if (err) {
1747 btrfs_tree_unlock(cur);
1748 free_extent_buffer(cur);
1749 break;
1750 }
1751 search_start = cur->start;
1752 last_block = cur->start;
1753 *last_ret = search_start;
1754 btrfs_tree_unlock(cur);
1755 free_extent_buffer(cur);
1756 }
1757 return err;
1758}
1759
1760/*
1761 * The leaf data grows from end-to-front in the node.
1762 * this returns the address of the start of the last item,
1763 * which is the stop of the leaf data stack
1764 */
1765static inline unsigned int leaf_data_end(struct btrfs_root *root,
1766 struct extent_buffer *leaf)
1767{
1768 u32 nr = btrfs_header_nritems(leaf);
1769 if (nr == 0)
1770 return BTRFS_LEAF_DATA_SIZE(root);
1771 return btrfs_item_offset_nr(leaf, nr - 1);
1772}
1773
1774
1775/*
1776 * search for key in the extent_buffer. The items start at offset p,
1777 * and they are item_size apart. There are 'max' items in p.
1778 *
1779 * the slot in the array is returned via slot, and it points to
1780 * the place where you would insert key if it is not found in
1781 * the array.
1782 *
1783 * slot may point to max if the key is bigger than all of the keys
1784 */
1785static noinline int generic_bin_search(struct extent_buffer *eb,
1786 unsigned long p,
1787 int item_size, struct btrfs_key *key,
1788 int max, int *slot)
1789{
1790 int low = 0;
1791 int high = max;
1792 int mid;
1793 int ret;
1794 struct btrfs_disk_key *tmp = NULL;
1795 struct btrfs_disk_key unaligned;
1796 unsigned long offset;
1797 char *kaddr = NULL;
1798 unsigned long map_start = 0;
1799 unsigned long map_len = 0;
1800 int err;
1801
1802 while (low < high) {
1803 mid = (low + high) / 2;
1804 offset = p + mid * item_size;
1805
1806 if (!kaddr || offset < map_start ||
1807 (offset + sizeof(struct btrfs_disk_key)) >
1808 map_start + map_len) {
1809
1810 err = map_private_extent_buffer(eb, offset,
1811 sizeof(struct btrfs_disk_key),
1812 &kaddr, &map_start, &map_len);
1813
1814 if (!err) {
1815 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1816 map_start);
1817 } else {
1818 read_extent_buffer(eb, &unaligned,
1819 offset, sizeof(unaligned));
1820 tmp = &unaligned;
1821 }
1822
1823 } else {
1824 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1825 map_start);
1826 }
1827 ret = comp_keys(tmp, key);
1828
1829 if (ret < 0)
1830 low = mid + 1;
1831 else if (ret > 0)
1832 high = mid;
1833 else {
1834 *slot = mid;
1835 return 0;
1836 }
1837 }
1838 *slot = low;
1839 return 1;
1840}
1841
1842/*
1843 * simple bin_search frontend that does the right thing for
1844 * leaves vs nodes
1845 */
1846static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
1847 int level, int *slot)
1848{
1849 if (level == 0)
1850 return generic_bin_search(eb,
1851 offsetof(struct btrfs_leaf, items),
1852 sizeof(struct btrfs_item),
1853 key, btrfs_header_nritems(eb),
1854 slot);
1855 else
1856 return generic_bin_search(eb,
1857 offsetof(struct btrfs_node, ptrs),
1858 sizeof(struct btrfs_key_ptr),
1859 key, btrfs_header_nritems(eb),
1860 slot);
1861}
1862
1863int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
1864 int level, int *slot)
1865{
1866 return bin_search(eb, key, level, slot);
1867}
1868
1869static void root_add_used(struct btrfs_root *root, u32 size)
1870{
1871 spin_lock(&root->accounting_lock);
1872 btrfs_set_root_used(&root->root_item,
1873 btrfs_root_used(&root->root_item) + size);
1874 spin_unlock(&root->accounting_lock);
1875}
1876
1877static void root_sub_used(struct btrfs_root *root, u32 size)
1878{
1879 spin_lock(&root->accounting_lock);
1880 btrfs_set_root_used(&root->root_item,
1881 btrfs_root_used(&root->root_item) - size);
1882 spin_unlock(&root->accounting_lock);
1883}
1884
1885/* given a node and slot number, this reads the blocks it points to. The
1886 * extent buffer is returned with a reference taken (but unlocked).
1887 * NULL is returned on error.
1888 */
1889static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root,
1890 struct extent_buffer *parent, int slot)
1891{
1892 int level = btrfs_header_level(parent);
1893 struct extent_buffer *eb;
1894
1895 if (slot < 0)
1896 return NULL;
1897 if (slot >= btrfs_header_nritems(parent))
1898 return NULL;
1899
1900 BUG_ON(level == 0);
1901
1902 eb = read_tree_block(root, btrfs_node_blockptr(parent, slot),
1903 btrfs_level_size(root, level - 1),
1904 btrfs_node_ptr_generation(parent, slot));
1905 if (eb && !extent_buffer_uptodate(eb)) {
1906 free_extent_buffer(eb);
1907 eb = NULL;
1908 }
1909
1910 return eb;
1911}
1912
1913/*
1914 * node level balancing, used to make sure nodes are in proper order for
1915 * item deletion. We balance from the top down, so we have to make sure
1916 * that a deletion won't leave an node completely empty later on.
1917 */
1918static noinline int balance_level(struct btrfs_trans_handle *trans,
1919 struct btrfs_root *root,
1920 struct btrfs_path *path, int level)
1921{
1922 struct extent_buffer *right = NULL;
1923 struct extent_buffer *mid;
1924 struct extent_buffer *left = NULL;
1925 struct extent_buffer *parent = NULL;
1926 int ret = 0;
1927 int wret;
1928 int pslot;
1929 int orig_slot = path->slots[level];
1930 u64 orig_ptr;
1931
1932 if (level == 0)
1933 return 0;
1934
1935 mid = path->nodes[level];
1936
1937 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1938 path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1939 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1940
1941 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1942
1943 if (level < BTRFS_MAX_LEVEL - 1) {
1944 parent = path->nodes[level + 1];
1945 pslot = path->slots[level + 1];
1946 }
1947
1948 /*
1949 * deal with the case where there is only one pointer in the root
1950 * by promoting the node below to a root
1951 */
1952 if (!parent) {
1953 struct extent_buffer *child;
1954
1955 if (btrfs_header_nritems(mid) != 1)
1956 return 0;
1957
1958 /* promote the child to a root */
1959 child = read_node_slot(root, mid, 0);
1960 if (!child) {
1961 ret = -EROFS;
1962 btrfs_std_error(root->fs_info, ret);
1963 goto enospc;
1964 }
1965
1966 btrfs_tree_lock(child);
1967 btrfs_set_lock_blocking(child);
1968 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1969 if (ret) {
1970 btrfs_tree_unlock(child);
1971 free_extent_buffer(child);
1972 goto enospc;
1973 }
1974
1975 tree_mod_log_set_root_pointer(root, child, 1);
1976 rcu_assign_pointer(root->node, child);
1977
1978 add_root_to_dirty_list(root);
1979 btrfs_tree_unlock(child);
1980
1981 path->locks[level] = 0;
1982 path->nodes[level] = NULL;
1983 clean_tree_block(trans, root, mid);
1984 btrfs_tree_unlock(mid);
1985 /* once for the path */
1986 free_extent_buffer(mid);
1987
1988 root_sub_used(root, mid->len);
1989 btrfs_free_tree_block(trans, root, mid, 0, 1);
1990 /* once for the root ptr */
1991 free_extent_buffer_stale(mid);
1992 return 0;
1993 }
1994 if (btrfs_header_nritems(mid) >
1995 BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
1996 return 0;
1997
1998 left = read_node_slot(root, parent, pslot - 1);
1999 if (left) {
2000 btrfs_tree_lock(left);
2001 btrfs_set_lock_blocking(left);
2002 wret = btrfs_cow_block(trans, root, left,
2003 parent, pslot - 1, &left);
2004 if (wret) {
2005 ret = wret;
2006 goto enospc;
2007 }
2008 }
2009 right = read_node_slot(root, parent, pslot + 1);
2010 if (right) {
2011 btrfs_tree_lock(right);
2012 btrfs_set_lock_blocking(right);
2013 wret = btrfs_cow_block(trans, root, right,
2014 parent, pslot + 1, &right);
2015 if (wret) {
2016 ret = wret;
2017 goto enospc;
2018 }
2019 }
2020
2021 /* first, try to make some room in the middle buffer */
2022 if (left) {
2023 orig_slot += btrfs_header_nritems(left);
2024 wret = push_node_left(trans, root, left, mid, 1);
2025 if (wret < 0)
2026 ret = wret;
2027 }
2028
2029 /*
2030 * then try to empty the right most buffer into the middle
2031 */
2032 if (right) {
2033 wret = push_node_left(trans, root, mid, right, 1);
2034 if (wret < 0 && wret != -ENOSPC)
2035 ret = wret;
2036 if (btrfs_header_nritems(right) == 0) {
2037 clean_tree_block(trans, root, right);
2038 btrfs_tree_unlock(right);
2039 del_ptr(root, path, level + 1, pslot + 1);
2040 root_sub_used(root, right->len);
2041 btrfs_free_tree_block(trans, root, right, 0, 1);
2042 free_extent_buffer_stale(right);
2043 right = NULL;
2044 } else {
2045 struct btrfs_disk_key right_key;
2046 btrfs_node_key(right, &right_key, 0);
2047 tree_mod_log_set_node_key(root->fs_info, parent,
2048 pslot + 1, 0);
2049 btrfs_set_node_key(parent, &right_key, pslot + 1);
2050 btrfs_mark_buffer_dirty(parent);
2051 }
2052 }
2053 if (btrfs_header_nritems(mid) == 1) {
2054 /*
2055 * we're not allowed to leave a node with one item in the
2056 * tree during a delete. A deletion from lower in the tree
2057 * could try to delete the only pointer in this node.
2058 * So, pull some keys from the left.
2059 * There has to be a left pointer at this point because
2060 * otherwise we would have pulled some pointers from the
2061 * right
2062 */
2063 if (!left) {
2064 ret = -EROFS;
2065 btrfs_std_error(root->fs_info, ret);
2066 goto enospc;
2067 }
2068 wret = balance_node_right(trans, root, mid, left);
2069 if (wret < 0) {
2070 ret = wret;
2071 goto enospc;
2072 }
2073 if (wret == 1) {
2074 wret = push_node_left(trans, root, left, mid, 1);
2075 if (wret < 0)
2076 ret = wret;
2077 }
2078 BUG_ON(wret == 1);
2079 }
2080 if (btrfs_header_nritems(mid) == 0) {
2081 clean_tree_block(trans, root, mid);
2082 btrfs_tree_unlock(mid);
2083 del_ptr(root, path, level + 1, pslot);
2084 root_sub_used(root, mid->len);
2085 btrfs_free_tree_block(trans, root, mid, 0, 1);
2086 free_extent_buffer_stale(mid);
2087 mid = NULL;
2088 } else {
2089 /* update the parent key to reflect our changes */
2090 struct btrfs_disk_key mid_key;
2091 btrfs_node_key(mid, &mid_key, 0);
2092 tree_mod_log_set_node_key(root->fs_info, parent,
2093 pslot, 0);
2094 btrfs_set_node_key(parent, &mid_key, pslot);
2095 btrfs_mark_buffer_dirty(parent);
2096 }
2097
2098 /* update the path */
2099 if (left) {
2100 if (btrfs_header_nritems(left) > orig_slot) {
2101 extent_buffer_get(left);
2102 /* left was locked after cow */
2103 path->nodes[level] = left;
2104 path->slots[level + 1] -= 1;
2105 path->slots[level] = orig_slot;
2106 if (mid) {
2107 btrfs_tree_unlock(mid);
2108 free_extent_buffer(mid);
2109 }
2110 } else {
2111 orig_slot -= btrfs_header_nritems(left);
2112 path->slots[level] = orig_slot;
2113 }
2114 }
2115 /* double check we haven't messed things up */
2116 if (orig_ptr !=
2117 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
2118 BUG();
2119enospc:
2120 if (right) {
2121 btrfs_tree_unlock(right);
2122 free_extent_buffer(right);
2123 }
2124 if (left) {
2125 if (path->nodes[level] != left)
2126 btrfs_tree_unlock(left);
2127 free_extent_buffer(left);
2128 }
2129 return ret;
2130}
2131
2132/* Node balancing for insertion. Here we only split or push nodes around
2133 * when they are completely full. This is also done top down, so we
2134 * have to be pessimistic.
2135 */
2136static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
2137 struct btrfs_root *root,
2138 struct btrfs_path *path, int level)
2139{
2140 struct extent_buffer *right = NULL;
2141 struct extent_buffer *mid;
2142 struct extent_buffer *left = NULL;
2143 struct extent_buffer *parent = NULL;
2144 int ret = 0;
2145 int wret;
2146 int pslot;
2147 int orig_slot = path->slots[level];
2148
2149 if (level == 0)
2150 return 1;
2151
2152 mid = path->nodes[level];
2153 WARN_ON(btrfs_header_generation(mid) != trans->transid);
2154
2155 if (level < BTRFS_MAX_LEVEL - 1) {
2156 parent = path->nodes[level + 1];
2157 pslot = path->slots[level + 1];
2158 }
2159
2160 if (!parent)
2161 return 1;
2162
2163 left = read_node_slot(root, parent, pslot - 1);
2164
2165 /* first, try to make some room in the middle buffer */
2166 if (left) {
2167 u32 left_nr;
2168
2169 btrfs_tree_lock(left);
2170 btrfs_set_lock_blocking(left);
2171
2172 left_nr = btrfs_header_nritems(left);
2173 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
2174 wret = 1;
2175 } else {
2176 ret = btrfs_cow_block(trans, root, left, parent,
2177 pslot - 1, &left);
2178 if (ret)
2179 wret = 1;
2180 else {
2181 wret = push_node_left(trans, root,
2182 left, mid, 0);
2183 }
2184 }
2185 if (wret < 0)
2186 ret = wret;
2187 if (wret == 0) {
2188 struct btrfs_disk_key disk_key;
2189 orig_slot += left_nr;
2190 btrfs_node_key(mid, &disk_key, 0);
2191 tree_mod_log_set_node_key(root->fs_info, parent,
2192 pslot, 0);
2193 btrfs_set_node_key(parent, &disk_key, pslot);
2194 btrfs_mark_buffer_dirty(parent);
2195 if (btrfs_header_nritems(left) > orig_slot) {
2196 path->nodes[level] = left;
2197 path->slots[level + 1] -= 1;
2198 path->slots[level] = orig_slot;
2199 btrfs_tree_unlock(mid);
2200 free_extent_buffer(mid);
2201 } else {
2202 orig_slot -=
2203 btrfs_header_nritems(left);
2204 path->slots[level] = orig_slot;
2205 btrfs_tree_unlock(left);
2206 free_extent_buffer(left);
2207 }
2208 return 0;
2209 }
2210 btrfs_tree_unlock(left);
2211 free_extent_buffer(left);
2212 }
2213 right = read_node_slot(root, parent, pslot + 1);
2214
2215 /*
2216 * then try to empty the right most buffer into the middle
2217 */
2218 if (right) {
2219 u32 right_nr;
2220
2221 btrfs_tree_lock(right);
2222 btrfs_set_lock_blocking(right);
2223
2224 right_nr = btrfs_header_nritems(right);
2225 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
2226 wret = 1;
2227 } else {
2228 ret = btrfs_cow_block(trans, root, right,
2229 parent, pslot + 1,
2230 &right);
2231 if (ret)
2232 wret = 1;
2233 else {
2234 wret = balance_node_right(trans, root,
2235 right, mid);
2236 }
2237 }
2238 if (wret < 0)
2239 ret = wret;
2240 if (wret == 0) {
2241 struct btrfs_disk_key disk_key;
2242
2243 btrfs_node_key(right, &disk_key, 0);
2244 tree_mod_log_set_node_key(root->fs_info, parent,
2245 pslot + 1, 0);
2246 btrfs_set_node_key(parent, &disk_key, pslot + 1);
2247 btrfs_mark_buffer_dirty(parent);
2248
2249 if (btrfs_header_nritems(mid) <= orig_slot) {
2250 path->nodes[level] = right;
2251 path->slots[level + 1] += 1;
2252 path->slots[level] = orig_slot -
2253 btrfs_header_nritems(mid);
2254 btrfs_tree_unlock(mid);
2255 free_extent_buffer(mid);
2256 } else {
2257 btrfs_tree_unlock(right);
2258 free_extent_buffer(right);
2259 }
2260 return 0;
2261 }
2262 btrfs_tree_unlock(right);
2263 free_extent_buffer(right);
2264 }
2265 return 1;
2266}
2267
2268/*
2269 * readahead one full node of leaves, finding things that are close
2270 * to the block in 'slot', and triggering ra on them.
2271 */
2272static void reada_for_search(struct btrfs_root *root,
2273 struct btrfs_path *path,
2274 int level, int slot, u64 objectid)
2275{
2276 struct extent_buffer *node;
2277 struct btrfs_disk_key disk_key;
2278 u32 nritems;
2279 u64 search;
2280 u64 target;
2281 u64 nread = 0;
2282 u64 gen;
2283 int direction = path->reada;
2284 struct extent_buffer *eb;
2285 u32 nr;
2286 u32 blocksize;
2287 u32 nscan = 0;
2288
2289 if (level != 1)
2290 return;
2291
2292 if (!path->nodes[level])
2293 return;
2294
2295 node = path->nodes[level];
2296
2297 search = btrfs_node_blockptr(node, slot);
2298 blocksize = btrfs_level_size(root, level - 1);
2299 eb = btrfs_find_tree_block(root, search, blocksize);
2300 if (eb) {
2301 free_extent_buffer(eb);
2302 return;
2303 }
2304
2305 target = search;
2306
2307 nritems = btrfs_header_nritems(node);
2308 nr = slot;
2309
2310 while (1) {
2311 if (direction < 0) {
2312 if (nr == 0)
2313 break;
2314 nr--;
2315 } else if (direction > 0) {
2316 nr++;
2317 if (nr >= nritems)
2318 break;
2319 }
2320 if (path->reada < 0 && objectid) {
2321 btrfs_node_key(node, &disk_key, nr);
2322 if (btrfs_disk_key_objectid(&disk_key) != objectid)
2323 break;
2324 }
2325 search = btrfs_node_blockptr(node, nr);
2326 if ((search <= target && target - search <= 65536) ||
2327 (search > target && search - target <= 65536)) {
2328 gen = btrfs_node_ptr_generation(node, nr);
2329 readahead_tree_block(root, search, blocksize, gen);
2330 nread += blocksize;
2331 }
2332 nscan++;
2333 if ((nread > 65536 || nscan > 32))
2334 break;
2335 }
2336}
2337
2338static noinline void reada_for_balance(struct btrfs_root *root,
2339 struct btrfs_path *path, int level)
2340{
2341 int slot;
2342 int nritems;
2343 struct extent_buffer *parent;
2344 struct extent_buffer *eb;
2345 u64 gen;
2346 u64 block1 = 0;
2347 u64 block2 = 0;
2348 int blocksize;
2349
2350 parent = path->nodes[level + 1];
2351 if (!parent)
2352 return;
2353
2354 nritems = btrfs_header_nritems(parent);
2355 slot = path->slots[level + 1];
2356 blocksize = btrfs_level_size(root, level);
2357
2358 if (slot > 0) {
2359 block1 = btrfs_node_blockptr(parent, slot - 1);
2360 gen = btrfs_node_ptr_generation(parent, slot - 1);
2361 eb = btrfs_find_tree_block(root, block1, blocksize);
2362 /*
2363 * if we get -eagain from btrfs_buffer_uptodate, we
2364 * don't want to return eagain here. That will loop
2365 * forever
2366 */
2367 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2368 block1 = 0;
2369 free_extent_buffer(eb);
2370 }
2371 if (slot + 1 < nritems) {
2372 block2 = btrfs_node_blockptr(parent, slot + 1);
2373 gen = btrfs_node_ptr_generation(parent, slot + 1);
2374 eb = btrfs_find_tree_block(root, block2, blocksize);
2375 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2376 block2 = 0;
2377 free_extent_buffer(eb);
2378 }
2379
2380 if (block1)
2381 readahead_tree_block(root, block1, blocksize, 0);
2382 if (block2)
2383 readahead_tree_block(root, block2, blocksize, 0);
2384}
2385
2386
2387/*
2388 * when we walk down the tree, it is usually safe to unlock the higher layers
2389 * in the tree. The exceptions are when our path goes through slot 0, because
2390 * operations on the tree might require changing key pointers higher up in the
2391 * tree.
2392 *
2393 * callers might also have set path->keep_locks, which tells this code to keep
2394 * the lock if the path points to the last slot in the block. This is part of
2395 * walking through the tree, and selecting the next slot in the higher block.
2396 *
2397 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
2398 * if lowest_unlock is 1, level 0 won't be unlocked
2399 */
2400static noinline void unlock_up(struct btrfs_path *path, int level,
2401 int lowest_unlock, int min_write_lock_level,
2402 int *write_lock_level)
2403{
2404 int i;
2405 int skip_level = level;
2406 int no_skips = 0;
2407 struct extent_buffer *t;
2408
2409 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2410 if (!path->nodes[i])
2411 break;
2412 if (!path->locks[i])
2413 break;
2414 if (!no_skips && path->slots[i] == 0) {
2415 skip_level = i + 1;
2416 continue;
2417 }
2418 if (!no_skips && path->keep_locks) {
2419 u32 nritems;
2420 t = path->nodes[i];
2421 nritems = btrfs_header_nritems(t);
2422 if (nritems < 1 || path->slots[i] >= nritems - 1) {
2423 skip_level = i + 1;
2424 continue;
2425 }
2426 }
2427 if (skip_level < i && i >= lowest_unlock)
2428 no_skips = 1;
2429
2430 t = path->nodes[i];
2431 if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
2432 btrfs_tree_unlock_rw(t, path->locks[i]);
2433 path->locks[i] = 0;
2434 if (write_lock_level &&
2435 i > min_write_lock_level &&
2436 i <= *write_lock_level) {
2437 *write_lock_level = i - 1;
2438 }
2439 }
2440 }
2441}
2442
2443/*
2444 * This releases any locks held in the path starting at level and
2445 * going all the way up to the root.
2446 *
2447 * btrfs_search_slot will keep the lock held on higher nodes in a few
2448 * corner cases, such as COW of the block at slot zero in the node. This
2449 * ignores those rules, and it should only be called when there are no
2450 * more updates to be done higher up in the tree.
2451 */
2452noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
2453{
2454 int i;
2455
2456 if (path->keep_locks)
2457 return;
2458
2459 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2460 if (!path->nodes[i])
2461 continue;
2462 if (!path->locks[i])
2463 continue;
2464 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
2465 path->locks[i] = 0;
2466 }
2467}
2468
2469/*
2470 * helper function for btrfs_search_slot. The goal is to find a block
2471 * in cache without setting the path to blocking. If we find the block
2472 * we return zero and the path is unchanged.
2473 *
2474 * If we can't find the block, we set the path blocking and do some
2475 * reada. -EAGAIN is returned and the search must be repeated.
2476 */
2477static int
2478read_block_for_search(struct btrfs_trans_handle *trans,
2479 struct btrfs_root *root, struct btrfs_path *p,
2480 struct extent_buffer **eb_ret, int level, int slot,
2481 struct btrfs_key *key, u64 time_seq)
2482{
2483 u64 blocknr;
2484 u64 gen;
2485 u32 blocksize;
2486 struct extent_buffer *b = *eb_ret;
2487 struct extent_buffer *tmp;
2488 int ret;
2489
2490 blocknr = btrfs_node_blockptr(b, slot);
2491 gen = btrfs_node_ptr_generation(b, slot);
2492 blocksize = btrfs_level_size(root, level - 1);
2493
2494 tmp = btrfs_find_tree_block(root, blocknr, blocksize);
2495 if (tmp) {
2496 /* first we do an atomic uptodate check */
2497 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2498 *eb_ret = tmp;
2499 return 0;
2500 }
2501
2502 /* the pages were up to date, but we failed
2503 * the generation number check. Do a full
2504 * read for the generation number that is correct.
2505 * We must do this without dropping locks so
2506 * we can trust our generation number
2507 */
2508 btrfs_set_path_blocking(p);
2509
2510 /* now we're allowed to do a blocking uptodate check */
2511 ret = btrfs_read_buffer(tmp, gen);
2512 if (!ret) {
2513 *eb_ret = tmp;
2514 return 0;
2515 }
2516 free_extent_buffer(tmp);
2517 btrfs_release_path(p);
2518 return -EIO;
2519 }
2520
2521 /*
2522 * reduce lock contention at high levels
2523 * of the btree by dropping locks before
2524 * we read. Don't release the lock on the current
2525 * level because we need to walk this node to figure
2526 * out which blocks to read.
2527 */
2528 btrfs_unlock_up_safe(p, level + 1);
2529 btrfs_set_path_blocking(p);
2530
2531 free_extent_buffer(tmp);
2532 if (p->reada)
2533 reada_for_search(root, p, level, slot, key->objectid);
2534
2535 btrfs_release_path(p);
2536
2537 ret = -EAGAIN;
2538 tmp = read_tree_block(root, blocknr, blocksize, 0);
2539 if (tmp) {
2540 /*
2541 * If the read above didn't mark this buffer up to date,
2542 * it will never end up being up to date. Set ret to EIO now
2543 * and give up so that our caller doesn't loop forever
2544 * on our EAGAINs.
2545 */
2546 if (!btrfs_buffer_uptodate(tmp, 0, 0))
2547 ret = -EIO;
2548 free_extent_buffer(tmp);
2549 }
2550 return ret;
2551}
2552
2553/*
2554 * helper function for btrfs_search_slot. This does all of the checks
2555 * for node-level blocks and does any balancing required based on
2556 * the ins_len.
2557 *
2558 * If no extra work was required, zero is returned. If we had to
2559 * drop the path, -EAGAIN is returned and btrfs_search_slot must
2560 * start over
2561 */
2562static int
2563setup_nodes_for_search(struct btrfs_trans_handle *trans,
2564 struct btrfs_root *root, struct btrfs_path *p,
2565 struct extent_buffer *b, int level, int ins_len,
2566 int *write_lock_level)
2567{
2568 int ret;
2569 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2570 BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
2571 int sret;
2572
2573 if (*write_lock_level < level + 1) {
2574 *write_lock_level = level + 1;
2575 btrfs_release_path(p);
2576 goto again;
2577 }
2578
2579 btrfs_set_path_blocking(p);
2580 reada_for_balance(root, p, level);
2581 sret = split_node(trans, root, p, level);
2582 btrfs_clear_path_blocking(p, NULL, 0);
2583
2584 BUG_ON(sret > 0);
2585 if (sret) {
2586 ret = sret;
2587 goto done;
2588 }
2589 b = p->nodes[level];
2590 } else if (ins_len < 0 && btrfs_header_nritems(b) <
2591 BTRFS_NODEPTRS_PER_BLOCK(root) / 2) {
2592 int sret;
2593
2594 if (*write_lock_level < level + 1) {
2595 *write_lock_level = level + 1;
2596 btrfs_release_path(p);
2597 goto again;
2598 }
2599
2600 btrfs_set_path_blocking(p);
2601 reada_for_balance(root, p, level);
2602 sret = balance_level(trans, root, p, level);
2603 btrfs_clear_path_blocking(p, NULL, 0);
2604
2605 if (sret) {
2606 ret = sret;
2607 goto done;
2608 }
2609 b = p->nodes[level];
2610 if (!b) {
2611 btrfs_release_path(p);
2612 goto again;
2613 }
2614 BUG_ON(btrfs_header_nritems(b) == 1);
2615 }
2616 return 0;
2617
2618again:
2619 ret = -EAGAIN;
2620done:
2621 return ret;
2622}
2623
2624static void key_search_validate(struct extent_buffer *b,
2625 struct btrfs_key *key,
2626 int level)
2627{
2628#ifdef CONFIG_BTRFS_ASSERT
2629 struct btrfs_disk_key disk_key;
2630
2631 btrfs_cpu_key_to_disk(&disk_key, key);
2632
2633 if (level == 0)
2634 ASSERT(!memcmp_extent_buffer(b, &disk_key,
2635 offsetof(struct btrfs_leaf, items[0].key),
2636 sizeof(disk_key)));
2637 else
2638 ASSERT(!memcmp_extent_buffer(b, &disk_key,
2639 offsetof(struct btrfs_node, ptrs[0].key),
2640 sizeof(disk_key)));
2641#endif
2642}
2643
2644static int key_search(struct extent_buffer *b, struct btrfs_key *key,
2645 int level, int *prev_cmp, int *slot)
2646{
2647 if (*prev_cmp != 0) {
2648 *prev_cmp = bin_search(b, key, level, slot);
2649 return *prev_cmp;
2650 }
2651
2652 key_search_validate(b, key, level);
2653 *slot = 0;
2654
2655 return 0;
2656}
2657
2658int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *found_path,
2659 u64 iobjectid, u64 ioff, u8 key_type,
2660 struct btrfs_key *found_key)
2661{
2662 int ret;
2663 struct btrfs_key key;
2664 struct extent_buffer *eb;
2665 struct btrfs_path *path;
2666
2667 key.type = key_type;
2668 key.objectid = iobjectid;
2669 key.offset = ioff;
2670
2671 if (found_path == NULL) {
2672 path = btrfs_alloc_path();
2673 if (!path)
2674 return -ENOMEM;
2675 } else
2676 path = found_path;
2677
2678 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
2679 if ((ret < 0) || (found_key == NULL)) {
2680 if (path != found_path)
2681 btrfs_free_path(path);
2682 return ret;
2683 }
2684
2685 eb = path->nodes[0];
2686 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
2687 ret = btrfs_next_leaf(fs_root, path);
2688 if (ret)
2689 return ret;
2690 eb = path->nodes[0];
2691 }
2692
2693 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
2694 if (found_key->type != key.type ||
2695 found_key->objectid != key.objectid)
2696 return 1;
2697
2698 return 0;
2699}
2700
2701/*
2702 * look for key in the tree. path is filled in with nodes along the way
2703 * if key is found, we return zero and you can find the item in the leaf
2704 * level of the path (level 0)
2705 *
2706 * If the key isn't found, the path points to the slot where it should
2707 * be inserted, and 1 is returned. If there are other errors during the
2708 * search a negative error number is returned.
2709 *
2710 * if ins_len > 0, nodes and leaves will be split as we walk down the
2711 * tree. if ins_len < 0, nodes will be merged as we walk down the tree (if
2712 * possible)
2713 */
2714int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
2715 *root, struct btrfs_key *key, struct btrfs_path *p, int
2716 ins_len, int cow)
2717{
2718 struct extent_buffer *b;
2719 int slot;
2720 int ret;
2721 int err;
2722 int level;
2723 int lowest_unlock = 1;
2724 int root_lock;
2725 /* everything at write_lock_level or lower must be write locked */
2726 int write_lock_level = 0;
2727 u8 lowest_level = 0;
2728 int min_write_lock_level;
2729 int prev_cmp;
2730
2731 lowest_level = p->lowest_level;
2732 WARN_ON(lowest_level && ins_len > 0);
2733 WARN_ON(p->nodes[0] != NULL);
2734 BUG_ON(!cow && ins_len);
2735
2736 if (ins_len < 0) {
2737 lowest_unlock = 2;
2738
2739 /* when we are removing items, we might have to go up to level
2740 * two as we update tree pointers Make sure we keep write
2741 * for those levels as well
2742 */
2743 write_lock_level = 2;
2744 } else if (ins_len > 0) {
2745 /*
2746 * for inserting items, make sure we have a write lock on
2747 * level 1 so we can update keys
2748 */
2749 write_lock_level = 1;
2750 }
2751
2752 if (!cow)
2753 write_lock_level = -1;
2754
2755 if (cow && (p->keep_locks || p->lowest_level))
2756 write_lock_level = BTRFS_MAX_LEVEL;
2757
2758 min_write_lock_level = write_lock_level;
2759
2760again:
2761 prev_cmp = -1;
2762 /*
2763 * we try very hard to do read locks on the root
2764 */
2765 root_lock = BTRFS_READ_LOCK;
2766 level = 0;
2767 if (p->search_commit_root) {
2768 /*
2769 * the commit roots are read only
2770 * so we always do read locks
2771 */
2772 if (p->need_commit_sem)
2773 down_read(&root->fs_info->commit_root_sem);
2774 b = root->commit_root;
2775 extent_buffer_get(b);
2776 level = btrfs_header_level(b);
2777 if (p->need_commit_sem)
2778 up_read(&root->fs_info->commit_root_sem);
2779 if (!p->skip_locking)
2780 btrfs_tree_read_lock(b);
2781 } else {
2782 if (p->skip_locking) {
2783 b = btrfs_root_node(root);
2784 level = btrfs_header_level(b);
2785 } else {
2786 /* we don't know the level of the root node
2787 * until we actually have it read locked
2788 */
2789 b = btrfs_read_lock_root_node(root);
2790 level = btrfs_header_level(b);
2791 if (level <= write_lock_level) {
2792 /* whoops, must trade for write lock */
2793 btrfs_tree_read_unlock(b);
2794 free_extent_buffer(b);
2795 b = btrfs_lock_root_node(root);
2796 root_lock = BTRFS_WRITE_LOCK;
2797
2798 /* the level might have changed, check again */
2799 level = btrfs_header_level(b);
2800 }
2801 }
2802 }
2803 p->nodes[level] = b;
2804 if (!p->skip_locking)
2805 p->locks[level] = root_lock;
2806
2807 while (b) {
2808 level = btrfs_header_level(b);
2809
2810 /*
2811 * setup the path here so we can release it under lock
2812 * contention with the cow code
2813 */
2814 if (cow) {
2815 /*
2816 * if we don't really need to cow this block
2817 * then we don't want to set the path blocking,
2818 * so we test it here
2819 */
2820 if (!should_cow_block(trans, root, b))
2821 goto cow_done;
2822
2823 btrfs_set_path_blocking(p);
2824
2825 /*
2826 * must have write locks on this node and the
2827 * parent
2828 */
2829 if (level > write_lock_level ||
2830 (level + 1 > write_lock_level &&
2831 level + 1 < BTRFS_MAX_LEVEL &&
2832 p->nodes[level + 1])) {
2833 write_lock_level = level + 1;
2834 btrfs_release_path(p);
2835 goto again;
2836 }
2837
2838 err = btrfs_cow_block(trans, root, b,
2839 p->nodes[level + 1],
2840 p->slots[level + 1], &b);
2841 if (err) {
2842 ret = err;
2843 goto done;
2844 }
2845 }
2846cow_done:
2847 p->nodes[level] = b;
2848 btrfs_clear_path_blocking(p, NULL, 0);
2849
2850 /*
2851 * we have a lock on b and as long as we aren't changing
2852 * the tree, there is no way to for the items in b to change.
2853 * It is safe to drop the lock on our parent before we
2854 * go through the expensive btree search on b.
2855 *
2856 * If we're inserting or deleting (ins_len != 0), then we might
2857 * be changing slot zero, which may require changing the parent.
2858 * So, we can't drop the lock until after we know which slot
2859 * we're operating on.
2860 */
2861 if (!ins_len && !p->keep_locks) {
2862 int u = level + 1;
2863
2864 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2865 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2866 p->locks[u] = 0;
2867 }
2868 }
2869
2870 ret = key_search(b, key, level, &prev_cmp, &slot);
2871
2872 if (level != 0) {
2873 int dec = 0;
2874 if (ret && slot > 0) {
2875 dec = 1;
2876 slot -= 1;
2877 }
2878 p->slots[level] = slot;
2879 err = setup_nodes_for_search(trans, root, p, b, level,
2880 ins_len, &write_lock_level);
2881 if (err == -EAGAIN)
2882 goto again;
2883 if (err) {
2884 ret = err;
2885 goto done;
2886 }
2887 b = p->nodes[level];
2888 slot = p->slots[level];
2889
2890 /*
2891 * slot 0 is special, if we change the key
2892 * we have to update the parent pointer
2893 * which means we must have a write lock
2894 * on the parent
2895 */
2896 if (slot == 0 && ins_len &&
2897 write_lock_level < level + 1) {
2898 write_lock_level = level + 1;
2899 btrfs_release_path(p);
2900 goto again;
2901 }
2902
2903 unlock_up(p, level, lowest_unlock,
2904 min_write_lock_level, &write_lock_level);
2905
2906 if (level == lowest_level) {
2907 if (dec)
2908 p->slots[level]++;
2909 goto done;
2910 }
2911
2912 err = read_block_for_search(trans, root, p,
2913 &b, level, slot, key, 0);
2914 if (err == -EAGAIN)
2915 goto again;
2916 if (err) {
2917 ret = err;
2918 goto done;
2919 }
2920
2921 if (!p->skip_locking) {
2922 level = btrfs_header_level(b);
2923 if (level <= write_lock_level) {
2924 err = btrfs_try_tree_write_lock(b);
2925 if (!err) {
2926 btrfs_set_path_blocking(p);
2927 btrfs_tree_lock(b);
2928 btrfs_clear_path_blocking(p, b,
2929 BTRFS_WRITE_LOCK);
2930 }
2931 p->locks[level] = BTRFS_WRITE_LOCK;
2932 } else {
2933 err = btrfs_try_tree_read_lock(b);
2934 if (!err) {
2935 btrfs_set_path_blocking(p);
2936 btrfs_tree_read_lock(b);
2937 btrfs_clear_path_blocking(p, b,
2938 BTRFS_READ_LOCK);
2939 }
2940 p->locks[level] = BTRFS_READ_LOCK;
2941 }
2942 p->nodes[level] = b;
2943 }
2944 } else {
2945 p->slots[level] = slot;
2946 if (ins_len > 0 &&
2947 btrfs_leaf_free_space(root, b) < ins_len) {
2948 if (write_lock_level < 1) {
2949 write_lock_level = 1;
2950 btrfs_release_path(p);
2951 goto again;
2952 }
2953
2954 btrfs_set_path_blocking(p);
2955 err = split_leaf(trans, root, key,
2956 p, ins_len, ret == 0);
2957 btrfs_clear_path_blocking(p, NULL, 0);
2958
2959 BUG_ON(err > 0);
2960 if (err) {
2961 ret = err;
2962 goto done;
2963 }
2964 }
2965 if (!p->search_for_split)
2966 unlock_up(p, level, lowest_unlock,
2967 min_write_lock_level, &write_lock_level);
2968 goto done;
2969 }
2970 }
2971 ret = 1;
2972done:
2973 /*
2974 * we don't really know what they plan on doing with the path
2975 * from here on, so for now just mark it as blocking
2976 */
2977 if (!p->leave_spinning)
2978 btrfs_set_path_blocking(p);
2979 if (ret < 0)
2980 btrfs_release_path(p);
2981 return ret;
2982}
2983
2984/*
2985 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2986 * current state of the tree together with the operations recorded in the tree
2987 * modification log to search for the key in a previous version of this tree, as
2988 * denoted by the time_seq parameter.
2989 *
2990 * Naturally, there is no support for insert, delete or cow operations.
2991 *
2992 * The resulting path and return value will be set up as if we called
2993 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2994 */
2995int btrfs_search_old_slot(struct btrfs_root *root, struct btrfs_key *key,
2996 struct btrfs_path *p, u64 time_seq)
2997{
2998 struct extent_buffer *b;
2999 int slot;
3000 int ret;
3001 int err;
3002 int level;
3003 int lowest_unlock = 1;
3004 u8 lowest_level = 0;
3005 int prev_cmp = -1;
3006
3007 lowest_level = p->lowest_level;
3008 WARN_ON(p->nodes[0] != NULL);
3009
3010 if (p->search_commit_root) {
3011 BUG_ON(time_seq);
3012 return btrfs_search_slot(NULL, root, key, p, 0, 0);
3013 }
3014
3015again:
3016 b = get_old_root(root, time_seq);
3017 level = btrfs_header_level(b);
3018 p->locks[level] = BTRFS_READ_LOCK;
3019
3020 while (b) {
3021 level = btrfs_header_level(b);
3022 p->nodes[level] = b;
3023 btrfs_clear_path_blocking(p, NULL, 0);
3024
3025 /*
3026 * we have a lock on b and as long as we aren't changing
3027 * the tree, there is no way to for the items in b to change.
3028 * It is safe to drop the lock on our parent before we
3029 * go through the expensive btree search on b.
3030 */
3031 btrfs_unlock_up_safe(p, level + 1);
3032
3033 /*
3034 * Since we can unwind eb's we want to do a real search every
3035 * time.
3036 */
3037 prev_cmp = -1;
3038 ret = key_search(b, key, level, &prev_cmp, &slot);
3039
3040 if (level != 0) {
3041 int dec = 0;
3042 if (ret && slot > 0) {
3043 dec = 1;
3044 slot -= 1;
3045 }
3046 p->slots[level] = slot;
3047 unlock_up(p, level, lowest_unlock, 0, NULL);
3048
3049 if (level == lowest_level) {
3050 if (dec)
3051 p->slots[level]++;
3052 goto done;
3053 }
3054
3055 err = read_block_for_search(NULL, root, p, &b, level,
3056 slot, key, time_seq);
3057 if (err == -EAGAIN)
3058 goto again;
3059 if (err) {
3060 ret = err;
3061 goto done;
3062 }
3063
3064 level = btrfs_header_level(b);
3065 err = btrfs_try_tree_read_lock(b);
3066 if (!err) {
3067 btrfs_set_path_blocking(p);
3068 btrfs_tree_read_lock(b);
3069 btrfs_clear_path_blocking(p, b,
3070 BTRFS_READ_LOCK);
3071 }
3072 b = tree_mod_log_rewind(root->fs_info, p, b, time_seq);
3073 if (!b) {
3074 ret = -ENOMEM;
3075 goto done;
3076 }
3077 p->locks[level] = BTRFS_READ_LOCK;
3078 p->nodes[level] = b;
3079 } else {
3080 p->slots[level] = slot;
3081 unlock_up(p, level, lowest_unlock, 0, NULL);
3082 goto done;
3083 }
3084 }
3085 ret = 1;
3086done:
3087 if (!p->leave_spinning)
3088 btrfs_set_path_blocking(p);
3089 if (ret < 0)
3090 btrfs_release_path(p);
3091
3092 return ret;
3093}
3094
3095/*
3096 * helper to use instead of search slot if no exact match is needed but
3097 * instead the next or previous item should be returned.
3098 * When find_higher is true, the next higher item is returned, the next lower
3099 * otherwise.
3100 * When return_any and find_higher are both true, and no higher item is found,
3101 * return the next lower instead.
3102 * When return_any is true and find_higher is false, and no lower item is found,
3103 * return the next higher instead.
3104 * It returns 0 if any item is found, 1 if none is found (tree empty), and
3105 * < 0 on error
3106 */
3107int btrfs_search_slot_for_read(struct btrfs_root *root,
3108 struct btrfs_key *key, struct btrfs_path *p,
3109 int find_higher, int return_any)
3110{
3111 int ret;
3112 struct extent_buffer *leaf;
3113
3114again:
3115 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
3116 if (ret <= 0)
3117 return ret;
3118 /*
3119 * a return value of 1 means the path is at the position where the
3120 * item should be inserted. Normally this is the next bigger item,
3121 * but in case the previous item is the last in a leaf, path points
3122 * to the first free slot in the previous leaf, i.e. at an invalid
3123 * item.
3124 */
3125 leaf = p->nodes[0];
3126
3127 if (find_higher) {
3128 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
3129 ret = btrfs_next_leaf(root, p);
3130 if (ret <= 0)
3131 return ret;
3132 if (!return_any)
3133 return 1;
3134 /*
3135 * no higher item found, return the next
3136 * lower instead
3137 */
3138 return_any = 0;
3139 find_higher = 0;
3140 btrfs_release_path(p);
3141 goto again;
3142 }
3143 } else {
3144 if (p->slots[0] == 0) {
3145 ret = btrfs_prev_leaf(root, p);
3146 if (ret < 0)
3147 return ret;
3148 if (!ret) {
3149 leaf = p->nodes[0];
3150 if (p->slots[0] == btrfs_header_nritems(leaf))
3151 p->slots[0]--;
3152 return 0;
3153 }
3154 if (!return_any)
3155 return 1;
3156 /*
3157 * no lower item found, return the next
3158 * higher instead
3159 */
3160 return_any = 0;
3161 find_higher = 1;
3162 btrfs_release_path(p);
3163 goto again;
3164 } else {
3165 --p->slots[0];
3166 }
3167 }
3168 return 0;
3169}
3170
3171/*
3172 * adjust the pointers going up the tree, starting at level
3173 * making sure the right key of each node is points to 'key'.
3174 * This is used after shifting pointers to the left, so it stops
3175 * fixing up pointers when a given leaf/node is not in slot 0 of the
3176 * higher levels
3177 *
3178 */
3179static void fixup_low_keys(struct btrfs_root *root, struct btrfs_path *path,
3180 struct btrfs_disk_key *key, int level)
3181{
3182 int i;
3183 struct extent_buffer *t;
3184
3185 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
3186 int tslot = path->slots[i];
3187 if (!path->nodes[i])
3188 break;
3189 t = path->nodes[i];
3190 tree_mod_log_set_node_key(root->fs_info, t, tslot, 1);
3191 btrfs_set_node_key(t, key, tslot);
3192 btrfs_mark_buffer_dirty(path->nodes[i]);
3193 if (tslot != 0)
3194 break;
3195 }
3196}
3197
3198/*
3199 * update item key.
3200 *
3201 * This function isn't completely safe. It's the caller's responsibility
3202 * that the new key won't break the order
3203 */
3204void btrfs_set_item_key_safe(struct btrfs_root *root, struct btrfs_path *path,
3205 struct btrfs_key *new_key)
3206{
3207 struct btrfs_disk_key disk_key;
3208 struct extent_buffer *eb;
3209 int slot;
3210
3211 eb = path->nodes[0];
3212 slot = path->slots[0];
3213 if (slot > 0) {
3214 btrfs_item_key(eb, &disk_key, slot - 1);
3215 BUG_ON(comp_keys(&disk_key, new_key) >= 0);
3216 }
3217 if (slot < btrfs_header_nritems(eb) - 1) {
3218 btrfs_item_key(eb, &disk_key, slot + 1);
3219 BUG_ON(comp_keys(&disk_key, new_key) <= 0);
3220 }
3221
3222 btrfs_cpu_key_to_disk(&disk_key, new_key);
3223 btrfs_set_item_key(eb, &disk_key, slot);
3224 btrfs_mark_buffer_dirty(eb);
3225 if (slot == 0)
3226 fixup_low_keys(root, path, &disk_key, 1);
3227}
3228
3229/*
3230 * try to push data from one node into the next node left in the
3231 * tree.
3232 *
3233 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
3234 * error, and > 0 if there was no room in the left hand block.
3235 */
3236static int push_node_left(struct btrfs_trans_handle *trans,
3237 struct btrfs_root *root, struct extent_buffer *dst,
3238 struct extent_buffer *src, int empty)
3239{
3240 int push_items = 0;
3241 int src_nritems;
3242 int dst_nritems;
3243 int ret = 0;
3244
3245 src_nritems = btrfs_header_nritems(src);
3246 dst_nritems = btrfs_header_nritems(dst);
3247 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
3248 WARN_ON(btrfs_header_generation(src) != trans->transid);
3249 WARN_ON(btrfs_header_generation(dst) != trans->transid);
3250
3251 if (!empty && src_nritems <= 8)
3252 return 1;
3253
3254 if (push_items <= 0)
3255 return 1;
3256
3257 if (empty) {
3258 push_items = min(src_nritems, push_items);
3259 if (push_items < src_nritems) {
3260 /* leave at least 8 pointers in the node if
3261 * we aren't going to empty it
3262 */
3263 if (src_nritems - push_items < 8) {
3264 if (push_items <= 8)
3265 return 1;
3266 push_items -= 8;
3267 }
3268 }
3269 } else
3270 push_items = min(src_nritems - 8, push_items);
3271
3272 ret = tree_mod_log_eb_copy(root->fs_info, dst, src, dst_nritems, 0,
3273 push_items);
3274 if (ret) {
3275 btrfs_abort_transaction(trans, root, ret);
3276 return ret;
3277 }
3278 copy_extent_buffer(dst, src,
3279 btrfs_node_key_ptr_offset(dst_nritems),
3280 btrfs_node_key_ptr_offset(0),
3281 push_items * sizeof(struct btrfs_key_ptr));
3282
3283 if (push_items < src_nritems) {
3284 /*
3285 * don't call tree_mod_log_eb_move here, key removal was already
3286 * fully logged by tree_mod_log_eb_copy above.
3287 */
3288 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
3289 btrfs_node_key_ptr_offset(push_items),
3290 (src_nritems - push_items) *
3291 sizeof(struct btrfs_key_ptr));
3292 }
3293 btrfs_set_header_nritems(src, src_nritems - push_items);
3294 btrfs_set_header_nritems(dst, dst_nritems + push_items);
3295 btrfs_mark_buffer_dirty(src);
3296 btrfs_mark_buffer_dirty(dst);
3297
3298 return ret;
3299}
3300
3301/*
3302 * try to push data from one node into the next node right in the
3303 * tree.
3304 *
3305 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
3306 * error, and > 0 if there was no room in the right hand block.
3307 *
3308 * this will only push up to 1/2 the contents of the left node over
3309 */
3310static int balance_node_right(struct btrfs_trans_handle *trans,
3311 struct btrfs_root *root,
3312 struct extent_buffer *dst,
3313 struct extent_buffer *src)
3314{
3315 int push_items = 0;
3316 int max_push;
3317 int src_nritems;
3318 int dst_nritems;
3319 int ret = 0;
3320
3321 WARN_ON(btrfs_header_generation(src) != trans->transid);
3322 WARN_ON(btrfs_header_generation(dst) != trans->transid);
3323
3324 src_nritems = btrfs_header_nritems(src);
3325 dst_nritems = btrfs_header_nritems(dst);
3326 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
3327 if (push_items <= 0)
3328 return 1;
3329
3330 if (src_nritems < 4)
3331 return 1;
3332
3333 max_push = src_nritems / 2 + 1;
3334 /* don't try to empty the node */
3335 if (max_push >= src_nritems)
3336 return 1;
3337
3338 if (max_push < push_items)
3339 push_items = max_push;
3340
3341 tree_mod_log_eb_move(root->fs_info, dst, push_items, 0, dst_nritems);
3342 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
3343 btrfs_node_key_ptr_offset(0),
3344 (dst_nritems) *
3345 sizeof(struct btrfs_key_ptr));
3346
3347 ret = tree_mod_log_eb_copy(root->fs_info, dst, src, 0,
3348 src_nritems - push_items, push_items);
3349 if (ret) {
3350 btrfs_abort_transaction(trans, root, ret);
3351 return ret;
3352 }
3353 copy_extent_buffer(dst, src,
3354 btrfs_node_key_ptr_offset(0),
3355 btrfs_node_key_ptr_offset(src_nritems - push_items),
3356 push_items * sizeof(struct btrfs_key_ptr));
3357
3358 btrfs_set_header_nritems(src, src_nritems - push_items);
3359 btrfs_set_header_nritems(dst, dst_nritems + push_items);
3360
3361 btrfs_mark_buffer_dirty(src);
3362 btrfs_mark_buffer_dirty(dst);
3363
3364 return ret;
3365}
3366
3367/*
3368 * helper function to insert a new root level in the tree.
3369 * A new node is allocated, and a single item is inserted to
3370 * point to the existing root
3371 *
3372 * returns zero on success or < 0 on failure.
3373 */
3374static noinline int insert_new_root(struct btrfs_trans_handle *trans,
3375 struct btrfs_root *root,
3376 struct btrfs_path *path, int level)
3377{
3378 u64 lower_gen;
3379 struct extent_buffer *lower;
3380 struct extent_buffer *c;
3381 struct extent_buffer *old;
3382 struct btrfs_disk_key lower_key;
3383
3384 BUG_ON(path->nodes[level]);
3385 BUG_ON(path->nodes[level-1] != root->node);
3386
3387 lower = path->nodes[level-1];
3388 if (level == 1)
3389 btrfs_item_key(lower, &lower_key, 0);
3390 else
3391 btrfs_node_key(lower, &lower_key, 0);
3392
3393 c = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
3394 root->root_key.objectid, &lower_key,
3395 level, root->node->start, 0);
3396 if (IS_ERR(c))
3397 return PTR_ERR(c);
3398
3399 root_add_used(root, root->nodesize);
3400
3401 memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
3402 btrfs_set_header_nritems(c, 1);
3403 btrfs_set_header_level(c, level);
3404 btrfs_set_header_bytenr(c, c->start);
3405 btrfs_set_header_generation(c, trans->transid);
3406 btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
3407 btrfs_set_header_owner(c, root->root_key.objectid);
3408
3409 write_extent_buffer(c, root->fs_info->fsid, btrfs_header_fsid(),
3410 BTRFS_FSID_SIZE);
3411
3412 write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
3413 btrfs_header_chunk_tree_uuid(c), BTRFS_UUID_SIZE);
3414
3415 btrfs_set_node_key(c, &lower_key, 0);
3416 btrfs_set_node_blockptr(c, 0, lower->start);
3417 lower_gen = btrfs_header_generation(lower);
3418 WARN_ON(lower_gen != trans->transid);
3419
3420 btrfs_set_node_ptr_generation(c, 0, lower_gen);
3421
3422 btrfs_mark_buffer_dirty(c);
3423
3424 old = root->node;
3425 tree_mod_log_set_root_pointer(root, c, 0);
3426 rcu_assign_pointer(root->node, c);
3427
3428 /* the super has an extra ref to root->node */
3429 free_extent_buffer(old);
3430
3431 add_root_to_dirty_list(root);
3432 extent_buffer_get(c);
3433 path->nodes[level] = c;
3434 path->locks[level] = BTRFS_WRITE_LOCK;
3435 path->slots[level] = 0;
3436 return 0;
3437}
3438
3439/*
3440 * worker function to insert a single pointer in a node.
3441 * the node should have enough room for the pointer already
3442 *
3443 * slot and level indicate where you want the key to go, and
3444 * blocknr is the block the key points to.
3445 */
3446static void insert_ptr(struct btrfs_trans_handle *trans,
3447 struct btrfs_root *root, struct btrfs_path *path,
3448 struct btrfs_disk_key *key, u64 bytenr,
3449 int slot, int level)
3450{
3451 struct extent_buffer *lower;
3452 int nritems;
3453 int ret;
3454
3455 BUG_ON(!path->nodes[level]);
3456 btrfs_assert_tree_locked(path->nodes[level]);
3457 lower = path->nodes[level];
3458 nritems = btrfs_header_nritems(lower);
3459 BUG_ON(slot > nritems);
3460 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(root));
3461 if (slot != nritems) {
3462 if (level)
3463 tree_mod_log_eb_move(root->fs_info, lower, slot + 1,
3464 slot, nritems - slot);
3465 memmove_extent_buffer(lower,
3466 btrfs_node_key_ptr_offset(slot + 1),
3467 btrfs_node_key_ptr_offset(slot),
3468 (nritems - slot) * sizeof(struct btrfs_key_ptr));
3469 }
3470 if (level) {
3471 ret = tree_mod_log_insert_key(root->fs_info, lower, slot,
3472 MOD_LOG_KEY_ADD, GFP_NOFS);
3473 BUG_ON(ret < 0);
3474 }
3475 btrfs_set_node_key(lower, key, slot);
3476 btrfs_set_node_blockptr(lower, slot, bytenr);
3477 WARN_ON(trans->transid == 0);
3478 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3479 btrfs_set_header_nritems(lower, nritems + 1);
3480 btrfs_mark_buffer_dirty(lower);
3481}
3482
3483/*
3484 * split the node at the specified level in path in two.
3485 * The path is corrected to point to the appropriate node after the split
3486 *
3487 * Before splitting this tries to make some room in the node by pushing
3488 * left and right, if either one works, it returns right away.
3489 *
3490 * returns 0 on success and < 0 on failure
3491 */
3492static noinline int split_node(struct btrfs_trans_handle *trans,
3493 struct btrfs_root *root,
3494 struct btrfs_path *path, int level)
3495{
3496 struct extent_buffer *c;
3497 struct extent_buffer *split;
3498 struct btrfs_disk_key disk_key;
3499 int mid;
3500 int ret;
3501 u32 c_nritems;
3502
3503 c = path->nodes[level];
3504 WARN_ON(btrfs_header_generation(c) != trans->transid);
3505 if (c == root->node) {
3506 /*
3507 * trying to split the root, lets make a new one
3508 *
3509 * tree mod log: We don't log_removal old root in
3510 * insert_new_root, because that root buffer will be kept as a
3511 * normal node. We are going to log removal of half of the
3512 * elements below with tree_mod_log_eb_copy. We're holding a
3513 * tree lock on the buffer, which is why we cannot race with
3514 * other tree_mod_log users.
3515 */
3516 ret = insert_new_root(trans, root, path, level + 1);
3517 if (ret)
3518 return ret;
3519 } else {
3520 ret = push_nodes_for_insert(trans, root, path, level);
3521 c = path->nodes[level];
3522 if (!ret && btrfs_header_nritems(c) <
3523 BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
3524 return 0;
3525 if (ret < 0)
3526 return ret;
3527 }
3528
3529 c_nritems = btrfs_header_nritems(c);
3530 mid = (c_nritems + 1) / 2;
3531 btrfs_node_key(c, &disk_key, mid);
3532
3533 split = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
3534 root->root_key.objectid,
3535 &disk_key, level, c->start, 0);
3536 if (IS_ERR(split))
3537 return PTR_ERR(split);
3538
3539 root_add_used(root, root->nodesize);
3540
3541 memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header));
3542 btrfs_set_header_level(split, btrfs_header_level(c));
3543 btrfs_set_header_bytenr(split, split->start);
3544 btrfs_set_header_generation(split, trans->transid);
3545 btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
3546 btrfs_set_header_owner(split, root->root_key.objectid);
3547 write_extent_buffer(split, root->fs_info->fsid,
3548 btrfs_header_fsid(), BTRFS_FSID_SIZE);
3549 write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
3550 btrfs_header_chunk_tree_uuid(split),
3551 BTRFS_UUID_SIZE);
3552
3553 ret = tree_mod_log_eb_copy(root->fs_info, split, c, 0,
3554 mid, c_nritems - mid);
3555 if (ret) {
3556 btrfs_abort_transaction(trans, root, ret);
3557 return ret;
3558 }
3559 copy_extent_buffer(split, c,
3560 btrfs_node_key_ptr_offset(0),
3561 btrfs_node_key_ptr_offset(mid),
3562 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3563 btrfs_set_header_nritems(split, c_nritems - mid);
3564 btrfs_set_header_nritems(c, mid);
3565 ret = 0;
3566
3567 btrfs_mark_buffer_dirty(c);
3568 btrfs_mark_buffer_dirty(split);
3569
3570 insert_ptr(trans, root, path, &disk_key, split->start,
3571 path->slots[level + 1] + 1, level + 1);
3572
3573 if (path->slots[level] >= mid) {
3574 path->slots[level] -= mid;
3575 btrfs_tree_unlock(c);
3576 free_extent_buffer(c);
3577 path->nodes[level] = split;
3578 path->slots[level + 1] += 1;
3579 } else {
3580 btrfs_tree_unlock(split);
3581 free_extent_buffer(split);
3582 }
3583 return ret;
3584}
3585
3586/*
3587 * how many bytes are required to store the items in a leaf. start
3588 * and nr indicate which items in the leaf to check. This totals up the
3589 * space used both by the item structs and the item data
3590 */
3591static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3592{
3593 struct btrfs_item *start_item;
3594 struct btrfs_item *end_item;
3595 struct btrfs_map_token token;
3596 int data_len;
3597 int nritems = btrfs_header_nritems(l);
3598 int end = min(nritems, start + nr) - 1;
3599
3600 if (!nr)
3601 return 0;
3602 btrfs_init_map_token(&token);
3603 start_item = btrfs_item_nr(start);
3604 end_item = btrfs_item_nr(end);
3605 data_len = btrfs_token_item_offset(l, start_item, &token) +
3606 btrfs_token_item_size(l, start_item, &token);
3607 data_len = data_len - btrfs_token_item_offset(l, end_item, &token);
3608 data_len += sizeof(struct btrfs_item) * nr;
3609 WARN_ON(data_len < 0);
3610 return data_len;
3611}
3612
3613/*
3614 * The space between the end of the leaf items and
3615 * the start of the leaf data. IOW, how much room
3616 * the leaf has left for both items and data
3617 */
3618noinline int btrfs_leaf_free_space(struct btrfs_root *root,
3619 struct extent_buffer *leaf)
3620{
3621 int nritems = btrfs_header_nritems(leaf);
3622 int ret;
3623 ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
3624 if (ret < 0) {
3625 btrfs_crit(root->fs_info,
3626 "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3627 ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
3628 leaf_space_used(leaf, 0, nritems), nritems);
3629 }
3630 return ret;
3631}
3632
3633/*
3634 * min slot controls the lowest index we're willing to push to the
3635 * right. We'll push up to and including min_slot, but no lower
3636 */
3637static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
3638 struct btrfs_root *root,
3639 struct btrfs_path *path,
3640 int data_size, int empty,
3641 struct extent_buffer *right,
3642 int free_space, u32 left_nritems,
3643 u32 min_slot)
3644{
3645 struct extent_buffer *left = path->nodes[0];
3646 struct extent_buffer *upper = path->nodes[1];
3647 struct btrfs_map_token token;
3648 struct btrfs_disk_key disk_key;
3649 int slot;
3650 u32 i;
3651 int push_space = 0;
3652 int push_items = 0;
3653 struct btrfs_item *item;
3654 u32 nr;
3655 u32 right_nritems;
3656 u32 data_end;
3657 u32 this_item_size;
3658
3659 btrfs_init_map_token(&token);
3660
3661 if (empty)
3662 nr = 0;
3663 else
3664 nr = max_t(u32, 1, min_slot);
3665
3666 if (path->slots[0] >= left_nritems)
3667 push_space += data_size;
3668
3669 slot = path->slots[1];
3670 i = left_nritems - 1;
3671 while (i >= nr) {
3672 item = btrfs_item_nr(i);
3673
3674 if (!empty && push_items > 0) {
3675 if (path->slots[0] > i)
3676 break;
3677 if (path->slots[0] == i) {
3678 int space = btrfs_leaf_free_space(root, left);
3679 if (space + push_space * 2 > free_space)
3680 break;
3681 }
3682 }
3683
3684 if (path->slots[0] == i)
3685 push_space += data_size;
3686
3687 this_item_size = btrfs_item_size(left, item);
3688 if (this_item_size + sizeof(*item) + push_space > free_space)
3689 break;
3690
3691 push_items++;
3692 push_space += this_item_size + sizeof(*item);
3693 if (i == 0)
3694 break;
3695 i--;
3696 }
3697
3698 if (push_items == 0)
3699 goto out_unlock;
3700
3701 WARN_ON(!empty && push_items == left_nritems);
3702
3703 /* push left to right */
3704 right_nritems = btrfs_header_nritems(right);
3705
3706 push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3707 push_space -= leaf_data_end(root, left);
3708
3709 /* make room in the right data area */
3710 data_end = leaf_data_end(root, right);
3711 memmove_extent_buffer(right,
3712 btrfs_leaf_data(right) + data_end - push_space,
3713 btrfs_leaf_data(right) + data_end,
3714 BTRFS_LEAF_DATA_SIZE(root) - data_end);
3715
3716 /* copy from the left data area */
3717 copy_extent_buffer(right, left, btrfs_leaf_data(right) +
3718 BTRFS_LEAF_DATA_SIZE(root) - push_space,
3719 btrfs_leaf_data(left) + leaf_data_end(root, left),
3720 push_space);
3721
3722 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3723 btrfs_item_nr_offset(0),
3724 right_nritems * sizeof(struct btrfs_item));
3725
3726 /* copy the items from left to right */
3727 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3728 btrfs_item_nr_offset(left_nritems - push_items),
3729 push_items * sizeof(struct btrfs_item));
3730
3731 /* update the item pointers */
3732 right_nritems += push_items;
3733 btrfs_set_header_nritems(right, right_nritems);
3734 push_space = BTRFS_LEAF_DATA_SIZE(root);
3735 for (i = 0; i < right_nritems; i++) {
3736 item = btrfs_item_nr(i);
3737 push_space -= btrfs_token_item_size(right, item, &token);
3738 btrfs_set_token_item_offset(right, item, push_space, &token);
3739 }
3740
3741 left_nritems -= push_items;
3742 btrfs_set_header_nritems(left, left_nritems);
3743
3744 if (left_nritems)
3745 btrfs_mark_buffer_dirty(left);
3746 else
3747 clean_tree_block(trans, root, left);
3748
3749 btrfs_mark_buffer_dirty(right);
3750
3751 btrfs_item_key(right, &disk_key, 0);
3752 btrfs_set_node_key(upper, &disk_key, slot + 1);
3753 btrfs_mark_buffer_dirty(upper);
3754
3755 /* then fixup the leaf pointer in the path */
3756 if (path->slots[0] >= left_nritems) {
3757 path->slots[0] -= left_nritems;
3758 if (btrfs_header_nritems(path->nodes[0]) == 0)
3759 clean_tree_block(trans, root, path->nodes[0]);
3760 btrfs_tree_unlock(path->nodes[0]);
3761 free_extent_buffer(path->nodes[0]);
3762 path->nodes[0] = right;
3763 path->slots[1] += 1;
3764 } else {
3765 btrfs_tree_unlock(right);
3766 free_extent_buffer(right);
3767 }
3768 return 0;
3769
3770out_unlock:
3771 btrfs_tree_unlock(right);
3772 free_extent_buffer(right);
3773 return 1;
3774}
3775
3776/*
3777 * push some data in the path leaf to the right, trying to free up at
3778 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3779 *
3780 * returns 1 if the push failed because the other node didn't have enough
3781 * room, 0 if everything worked out and < 0 if there were major errors.
3782 *
3783 * this will push starting from min_slot to the end of the leaf. It won't
3784 * push any slot lower than min_slot
3785 */
3786static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3787 *root, struct btrfs_path *path,
3788 int min_data_size, int data_size,
3789 int empty, u32 min_slot)
3790{
3791 struct extent_buffer *left = path->nodes[0];
3792 struct extent_buffer *right;
3793 struct extent_buffer *upper;
3794 int slot;
3795 int free_space;
3796 u32 left_nritems;
3797 int ret;
3798
3799 if (!path->nodes[1])
3800 return 1;
3801
3802 slot = path->slots[1];
3803 upper = path->nodes[1];
3804 if (slot >= btrfs_header_nritems(upper) - 1)
3805 return 1;
3806
3807 btrfs_assert_tree_locked(path->nodes[1]);
3808
3809 right = read_node_slot(root, upper, slot + 1);
3810 if (right == NULL)
3811 return 1;
3812
3813 btrfs_tree_lock(right);
3814 btrfs_set_lock_blocking(right);
3815
3816 free_space = btrfs_leaf_free_space(root, right);
3817 if (free_space < data_size)
3818 goto out_unlock;
3819
3820 /* cow and double check */
3821 ret = btrfs_cow_block(trans, root, right, upper,
3822 slot + 1, &right);
3823 if (ret)
3824 goto out_unlock;
3825
3826 free_space = btrfs_leaf_free_space(root, right);
3827 if (free_space < data_size)
3828 goto out_unlock;
3829
3830 left_nritems = btrfs_header_nritems(left);
3831 if (left_nritems == 0)
3832 goto out_unlock;
3833
3834 if (path->slots[0] == left_nritems && !empty) {
3835 /* Key greater than all keys in the leaf, right neighbor has
3836 * enough room for it and we're not emptying our leaf to delete
3837 * it, therefore use right neighbor to insert the new item and
3838 * no need to touch/dirty our left leaft. */
3839 btrfs_tree_unlock(left);
3840 free_extent_buffer(left);
3841 path->nodes[0] = right;
3842 path->slots[0] = 0;
3843 path->slots[1]++;
3844 return 0;
3845 }
3846
3847 return __push_leaf_right(trans, root, path, min_data_size, empty,
3848 right, free_space, left_nritems, min_slot);
3849out_unlock:
3850 btrfs_tree_unlock(right);
3851 free_extent_buffer(right);
3852 return 1;
3853}
3854
3855/*
3856 * push some data in the path leaf to the left, trying to free up at
3857 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3858 *
3859 * max_slot can put a limit on how far into the leaf we'll push items. The
3860 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3861 * items
3862 */
3863static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
3864 struct btrfs_root *root,
3865 struct btrfs_path *path, int data_size,
3866 int empty, struct extent_buffer *left,
3867 int free_space, u32 right_nritems,
3868 u32 max_slot)
3869{
3870 struct btrfs_disk_key disk_key;
3871 struct extent_buffer *right = path->nodes[0];
3872 int i;
3873 int push_space = 0;
3874 int push_items = 0;
3875 struct btrfs_item *item;
3876 u32 old_left_nritems;
3877 u32 nr;
3878 int ret = 0;
3879 u32 this_item_size;
3880 u32 old_left_item_size;
3881 struct btrfs_map_token token;
3882
3883 btrfs_init_map_token(&token);
3884
3885 if (empty)
3886 nr = min(right_nritems, max_slot);
3887 else
3888 nr = min(right_nritems - 1, max_slot);
3889
3890 for (i = 0; i < nr; i++) {
3891 item = btrfs_item_nr(i);
3892
3893 if (!empty && push_items > 0) {
3894 if (path->slots[0] < i)
3895 break;
3896 if (path->slots[0] == i) {
3897 int space = btrfs_leaf_free_space(root, right);
3898 if (space + push_space * 2 > free_space)
3899 break;
3900 }
3901 }
3902
3903 if (path->slots[0] == i)
3904 push_space += data_size;
3905
3906 this_item_size = btrfs_item_size(right, item);
3907 if (this_item_size + sizeof(*item) + push_space > free_space)
3908 break;
3909
3910 push_items++;
3911 push_space += this_item_size + sizeof(*item);
3912 }
3913
3914 if (push_items == 0) {
3915 ret = 1;
3916 goto out;
3917 }
3918 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3919
3920 /* push data from right to left */
3921 copy_extent_buffer(left, right,
3922 btrfs_item_nr_offset(btrfs_header_nritems(left)),
3923 btrfs_item_nr_offset(0),
3924 push_items * sizeof(struct btrfs_item));
3925
3926 push_space = BTRFS_LEAF_DATA_SIZE(root) -
3927 btrfs_item_offset_nr(right, push_items - 1);
3928
3929 copy_extent_buffer(left, right, btrfs_leaf_data(left) +
3930 leaf_data_end(root, left) - push_space,
3931 btrfs_leaf_data(right) +
3932 btrfs_item_offset_nr(right, push_items - 1),
3933 push_space);
3934 old_left_nritems = btrfs_header_nritems(left);
3935 BUG_ON(old_left_nritems <= 0);
3936
3937 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3938 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3939 u32 ioff;
3940
3941 item = btrfs_item_nr(i);
3942
3943 ioff = btrfs_token_item_offset(left, item, &token);
3944 btrfs_set_token_item_offset(left, item,
3945 ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size),
3946 &token);
3947 }
3948 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3949
3950 /* fixup right node */
3951 if (push_items > right_nritems)
3952 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3953 right_nritems);
3954
3955 if (push_items < right_nritems) {
3956 push_space = btrfs_item_offset_nr(right, push_items - 1) -
3957 leaf_data_end(root, right);
3958 memmove_extent_buffer(right, btrfs_leaf_data(right) +
3959 BTRFS_LEAF_DATA_SIZE(root) - push_space,
3960 btrfs_leaf_data(right) +
3961 leaf_data_end(root, right), push_space);
3962
3963 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3964 btrfs_item_nr_offset(push_items),
3965 (btrfs_header_nritems(right) - push_items) *
3966 sizeof(struct btrfs_item));
3967 }
3968 right_nritems -= push_items;
3969 btrfs_set_header_nritems(right, right_nritems);
3970 push_space = BTRFS_LEAF_DATA_SIZE(root);
3971 for (i = 0; i < right_nritems; i++) {
3972 item = btrfs_item_nr(i);
3973
3974 push_space = push_space - btrfs_token_item_size(right,
3975 item, &token);
3976 btrfs_set_token_item_offset(right, item, push_space, &token);
3977 }
3978
3979 btrfs_mark_buffer_dirty(left);
3980 if (right_nritems)
3981 btrfs_mark_buffer_dirty(right);
3982 else
3983 clean_tree_block(trans, root, right);
3984
3985 btrfs_item_key(right, &disk_key, 0);
3986 fixup_low_keys(root, path, &disk_key, 1);
3987
3988 /* then fixup the leaf pointer in the path */
3989 if (path->slots[0] < push_items) {
3990 path->slots[0] += old_left_nritems;
3991 btrfs_tree_unlock(path->nodes[0]);
3992 free_extent_buffer(path->nodes[0]);
3993 path->nodes[0] = left;
3994 path->slots[1] -= 1;
3995 } else {
3996 btrfs_tree_unlock(left);
3997 free_extent_buffer(left);
3998 path->slots[0] -= push_items;
3999 }
4000 BUG_ON(path->slots[0] < 0);
4001 return ret;
4002out:
4003 btrfs_tree_unlock(left);
4004 free_extent_buffer(left);
4005 return ret;
4006}
4007
4008/*
4009 * push some data in the path leaf to the left, trying to free up at
4010 * least data_size bytes. returns zero if the push worked, nonzero otherwise
4011 *
4012 * max_slot can put a limit on how far into the leaf we'll push items. The
4013 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
4014 * items
4015 */
4016static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
4017 *root, struct btrfs_path *path, int min_data_size,
4018 int data_size, int empty, u32 max_slot)
4019{
4020 struct extent_buffer *right = path->nodes[0];
4021 struct extent_buffer *left;
4022 int slot;
4023 int free_space;
4024 u32 right_nritems;
4025 int ret = 0;
4026
4027 slot = path->slots[1];
4028 if (slot == 0)
4029 return 1;
4030 if (!path->nodes[1])
4031 return 1;
4032
4033 right_nritems = btrfs_header_nritems(right);
4034 if (right_nritems == 0)
4035 return 1;
4036
4037 btrfs_assert_tree_locked(path->nodes[1]);
4038
4039 left = read_node_slot(root, path->nodes[1], slot - 1);
4040 if (left == NULL)
4041 return 1;
4042
4043 btrfs_tree_lock(left);
4044 btrfs_set_lock_blocking(left);
4045
4046 free_space = btrfs_leaf_free_space(root, left);
4047 if (free_space < data_size) {
4048 ret = 1;
4049 goto out;
4050 }
4051
4052 /* cow and double check */
4053 ret = btrfs_cow_block(trans, root, left,
4054 path->nodes[1], slot - 1, &left);
4055 if (ret) {
4056 /* we hit -ENOSPC, but it isn't fatal here */
4057 if (ret == -ENOSPC)
4058 ret = 1;
4059 goto out;
4060 }
4061
4062 free_space = btrfs_leaf_free_space(root, left);
4063 if (free_space < data_size) {
4064 ret = 1;
4065 goto out;
4066 }
4067
4068 return __push_leaf_left(trans, root, path, min_data_size,
4069 empty, left, free_space, right_nritems,
4070 max_slot);
4071out:
4072 btrfs_tree_unlock(left);
4073 free_extent_buffer(left);
4074 return ret;
4075}
4076
4077/*
4078 * split the path's leaf in two, making sure there is at least data_size
4079 * available for the resulting leaf level of the path.
4080 */
4081static noinline void copy_for_split(struct btrfs_trans_handle *trans,
4082 struct btrfs_root *root,
4083 struct btrfs_path *path,
4084 struct extent_buffer *l,
4085 struct extent_buffer *right,
4086 int slot, int mid, int nritems)
4087{
4088 int data_copy_size;
4089 int rt_data_off;
4090 int i;
4091 struct btrfs_disk_key disk_key;
4092 struct btrfs_map_token token;
4093
4094 btrfs_init_map_token(&token);
4095
4096 nritems = nritems - mid;
4097 btrfs_set_header_nritems(right, nritems);
4098 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
4099
4100 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
4101 btrfs_item_nr_offset(mid),
4102 nritems * sizeof(struct btrfs_item));
4103
4104 copy_extent_buffer(right, l,
4105 btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
4106 data_copy_size, btrfs_leaf_data(l) +
4107 leaf_data_end(root, l), data_copy_size);
4108
4109 rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
4110 btrfs_item_end_nr(l, mid);
4111
4112 for (i = 0; i < nritems; i++) {
4113 struct btrfs_item *item = btrfs_item_nr(i);
4114 u32 ioff;
4115
4116 ioff = btrfs_token_item_offset(right, item, &token);
4117 btrfs_set_token_item_offset(right, item,
4118 ioff + rt_data_off, &token);
4119 }
4120
4121 btrfs_set_header_nritems(l, mid);
4122 btrfs_item_key(right, &disk_key, 0);
4123 insert_ptr(trans, root, path, &disk_key, right->start,
4124 path->slots[1] + 1, 1);
4125
4126 btrfs_mark_buffer_dirty(right);
4127 btrfs_mark_buffer_dirty(l);
4128 BUG_ON(path->slots[0] != slot);
4129
4130 if (mid <= slot) {
4131 btrfs_tree_unlock(path->nodes[0]);
4132 free_extent_buffer(path->nodes[0]);
4133 path->nodes[0] = right;
4134 path->slots[0] -= mid;
4135 path->slots[1] += 1;
4136 } else {
4137 btrfs_tree_unlock(right);
4138 free_extent_buffer(right);
4139 }
4140
4141 BUG_ON(path->slots[0] < 0);
4142}
4143
4144/*
4145 * double splits happen when we need to insert a big item in the middle
4146 * of a leaf. A double split can leave us with 3 mostly empty leaves:
4147 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
4148 * A B C
4149 *
4150 * We avoid this by trying to push the items on either side of our target
4151 * into the adjacent leaves. If all goes well we can avoid the double split
4152 * completely.
4153 */
4154static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
4155 struct btrfs_root *root,
4156 struct btrfs_path *path,
4157 int data_size)
4158{
4159 int ret;
4160 int progress = 0;
4161 int slot;
4162 u32 nritems;
4163 int space_needed = data_size;
4164
4165 slot = path->slots[0];
4166 if (slot < btrfs_header_nritems(path->nodes[0]))
4167 space_needed -= btrfs_leaf_free_space(root, path->nodes[0]);
4168
4169 /*
4170 * try to push all the items after our slot into the
4171 * right leaf
4172 */
4173 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
4174 if (ret < 0)
4175 return ret;
4176
4177 if (ret == 0)
4178 progress++;
4179
4180 nritems = btrfs_header_nritems(path->nodes[0]);
4181 /*
4182 * our goal is to get our slot at the start or end of a leaf. If
4183 * we've done so we're done
4184 */
4185 if (path->slots[0] == 0 || path->slots[0] == nritems)
4186 return 0;
4187
4188 if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
4189 return 0;
4190
4191 /* try to push all the items before our slot into the next leaf */
4192 slot = path->slots[0];
4193 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
4194 if (ret < 0)
4195 return ret;
4196
4197 if (ret == 0)
4198 progress++;
4199
4200 if (progress)
4201 return 0;
4202 return 1;
4203}
4204
4205/*
4206 * split the path's leaf in two, making sure there is at least data_size
4207 * available for the resulting leaf level of the path.
4208 *
4209 * returns 0 if all went well and < 0 on failure.
4210 */
4211static noinline int split_leaf(struct btrfs_trans_handle *trans,
4212 struct btrfs_root *root,
4213 struct btrfs_key *ins_key,
4214 struct btrfs_path *path, int data_size,
4215 int extend)
4216{
4217 struct btrfs_disk_key disk_key;
4218 struct extent_buffer *l;
4219 u32 nritems;
4220 int mid;
4221 int slot;
4222 struct extent_buffer *right;
4223 int ret = 0;
4224 int wret;
4225 int split;
4226 int num_doubles = 0;
4227 int tried_avoid_double = 0;
4228
4229 l = path->nodes[0];
4230 slot = path->slots[0];
4231 if (extend && data_size + btrfs_item_size_nr(l, slot) +
4232 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root))
4233 return -EOVERFLOW;
4234
4235 /* first try to make some room by pushing left and right */
4236 if (data_size && path->nodes[1]) {
4237 int space_needed = data_size;
4238
4239 if (slot < btrfs_header_nritems(l))
4240 space_needed -= btrfs_leaf_free_space(root, l);
4241
4242 wret = push_leaf_right(trans, root, path, space_needed,
4243 space_needed, 0, 0);
4244 if (wret < 0)
4245 return wret;
4246 if (wret) {
4247 wret = push_leaf_left(trans, root, path, space_needed,
4248 space_needed, 0, (u32)-1);
4249 if (wret < 0)
4250 return wret;
4251 }
4252 l = path->nodes[0];
4253
4254 /* did the pushes work? */
4255 if (btrfs_leaf_free_space(root, l) >= data_size)
4256 return 0;
4257 }
4258
4259 if (!path->nodes[1]) {
4260 ret = insert_new_root(trans, root, path, 1);
4261 if (ret)
4262 return ret;
4263 }
4264again:
4265 split = 1;
4266 l = path->nodes[0];
4267 slot = path->slots[0];
4268 nritems = btrfs_header_nritems(l);
4269 mid = (nritems + 1) / 2;
4270
4271 if (mid <= slot) {
4272 if (nritems == 1 ||
4273 leaf_space_used(l, mid, nritems - mid) + data_size >
4274 BTRFS_LEAF_DATA_SIZE(root)) {
4275 if (slot >= nritems) {
4276 split = 0;
4277 } else {
4278 mid = slot;
4279 if (mid != nritems &&
4280 leaf_space_used(l, mid, nritems - mid) +
4281 data_size > BTRFS_LEAF_DATA_SIZE(root)) {
4282 if (data_size && !tried_avoid_double)
4283 goto push_for_double;
4284 split = 2;
4285 }
4286 }
4287 }
4288 } else {
4289 if (leaf_space_used(l, 0, mid) + data_size >
4290 BTRFS_LEAF_DATA_SIZE(root)) {
4291 if (!extend && data_size && slot == 0) {
4292 split = 0;
4293 } else if ((extend || !data_size) && slot == 0) {
4294 mid = 1;
4295 } else {
4296 mid = slot;
4297 if (mid != nritems &&
4298 leaf_space_used(l, mid, nritems - mid) +
4299 data_size > BTRFS_LEAF_DATA_SIZE(root)) {
4300 if (data_size && !tried_avoid_double)
4301 goto push_for_double;
4302 split = 2;
4303 }
4304 }
4305 }
4306 }
4307
4308 if (split == 0)
4309 btrfs_cpu_key_to_disk(&disk_key, ins_key);
4310 else
4311 btrfs_item_key(l, &disk_key, mid);
4312
4313 right = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
4314 root->root_key.objectid,
4315 &disk_key, 0, l->start, 0);
4316 if (IS_ERR(right))
4317 return PTR_ERR(right);
4318
4319 root_add_used(root, root->leafsize);
4320
4321 memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
4322 btrfs_set_header_bytenr(right, right->start);
4323 btrfs_set_header_generation(right, trans->transid);
4324 btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
4325 btrfs_set_header_owner(right, root->root_key.objectid);
4326 btrfs_set_header_level(right, 0);
4327 write_extent_buffer(right, root->fs_info->fsid,
4328 btrfs_header_fsid(), BTRFS_FSID_SIZE);
4329
4330 write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
4331 btrfs_header_chunk_tree_uuid(right),
4332 BTRFS_UUID_SIZE);
4333
4334 if (split == 0) {
4335 if (mid <= slot) {
4336 btrfs_set_header_nritems(right, 0);
4337 insert_ptr(trans, root, path, &disk_key, right->start,
4338 path->slots[1] + 1, 1);
4339 btrfs_tree_unlock(path->nodes[0]);
4340 free_extent_buffer(path->nodes[0]);
4341 path->nodes[0] = right;
4342 path->slots[0] = 0;
4343 path->slots[1] += 1;
4344 } else {
4345 btrfs_set_header_nritems(right, 0);
4346 insert_ptr(trans, root, path, &disk_key, right->start,
4347 path->slots[1], 1);
4348 btrfs_tree_unlock(path->nodes[0]);
4349 free_extent_buffer(path->nodes[0]);
4350 path->nodes[0] = right;
4351 path->slots[0] = 0;
4352 if (path->slots[1] == 0)
4353 fixup_low_keys(root, path, &disk_key, 1);
4354 }
4355 btrfs_mark_buffer_dirty(right);
4356 return ret;
4357 }
4358
4359 copy_for_split(trans, root, path, l, right, slot, mid, nritems);
4360
4361 if (split == 2) {
4362 BUG_ON(num_doubles != 0);
4363 num_doubles++;
4364 goto again;
4365 }
4366
4367 return 0;
4368
4369push_for_double:
4370 push_for_double_split(trans, root, path, data_size);
4371 tried_avoid_double = 1;
4372 if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
4373 return 0;
4374 goto again;
4375}
4376
4377static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
4378 struct btrfs_root *root,
4379 struct btrfs_path *path, int ins_len)
4380{
4381 struct btrfs_key key;
4382 struct extent_buffer *leaf;
4383 struct btrfs_file_extent_item *fi;
4384 u64 extent_len = 0;
4385 u32 item_size;
4386 int ret;
4387
4388 leaf = path->nodes[0];
4389 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4390
4391 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
4392 key.type != BTRFS_EXTENT_CSUM_KEY);
4393
4394 if (btrfs_leaf_free_space(root, leaf) >= ins_len)
4395 return 0;
4396
4397 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4398 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4399 fi = btrfs_item_ptr(leaf, path->slots[0],
4400 struct btrfs_file_extent_item);
4401 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
4402 }
4403 btrfs_release_path(path);
4404
4405 path->keep_locks = 1;
4406 path->search_for_split = 1;
4407 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
4408 path->search_for_split = 0;
4409 if (ret < 0)
4410 goto err;
4411
4412 ret = -EAGAIN;
4413 leaf = path->nodes[0];
4414 /* if our item isn't there or got smaller, return now */
4415 if (ret > 0 || item_size != btrfs_item_size_nr(leaf, path->slots[0]))
4416 goto err;
4417
4418 /* the leaf has changed, it now has room. return now */
4419 if (btrfs_leaf_free_space(root, path->nodes[0]) >= ins_len)
4420 goto err;
4421
4422 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4423 fi = btrfs_item_ptr(leaf, path->slots[0],
4424 struct btrfs_file_extent_item);
4425 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
4426 goto err;
4427 }
4428
4429 btrfs_set_path_blocking(path);
4430 ret = split_leaf(trans, root, &key, path, ins_len, 1);
4431 if (ret)
4432 goto err;
4433
4434 path->keep_locks = 0;
4435 btrfs_unlock_up_safe(path, 1);
4436 return 0;
4437err:
4438 path->keep_locks = 0;
4439 return ret;
4440}
4441
4442static noinline int split_item(struct btrfs_trans_handle *trans,
4443 struct btrfs_root *root,
4444 struct btrfs_path *path,
4445 struct btrfs_key *new_key,
4446 unsigned long split_offset)
4447{
4448 struct extent_buffer *leaf;
4449 struct btrfs_item *item;
4450 struct btrfs_item *new_item;
4451 int slot;
4452 char *buf;
4453 u32 nritems;
4454 u32 item_size;
4455 u32 orig_offset;
4456 struct btrfs_disk_key disk_key;
4457
4458 leaf = path->nodes[0];
4459 BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
4460
4461 btrfs_set_path_blocking(path);
4462
4463 item = btrfs_item_nr(path->slots[0]);
4464 orig_offset = btrfs_item_offset(leaf, item);
4465 item_size = btrfs_item_size(leaf, item);
4466
4467 buf = kmalloc(item_size, GFP_NOFS);
4468 if (!buf)
4469 return -ENOMEM;
4470
4471 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
4472 path->slots[0]), item_size);
4473
4474 slot = path->slots[0] + 1;
4475 nritems = btrfs_header_nritems(leaf);
4476 if (slot != nritems) {
4477 /* shift the items */
4478 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
4479 btrfs_item_nr_offset(slot),
4480 (nritems - slot) * sizeof(struct btrfs_item));
4481 }
4482
4483 btrfs_cpu_key_to_disk(&disk_key, new_key);
4484 btrfs_set_item_key(leaf, &disk_key, slot);
4485
4486 new_item = btrfs_item_nr(slot);
4487
4488 btrfs_set_item_offset(leaf, new_item, orig_offset);
4489 btrfs_set_item_size(leaf, new_item, item_size - split_offset);
4490
4491 btrfs_set_item_offset(leaf, item,
4492 orig_offset + item_size - split_offset);
4493 btrfs_set_item_size(leaf, item, split_offset);
4494
4495 btrfs_set_header_nritems(leaf, nritems + 1);
4496
4497 /* write the data for the start of the original item */
4498 write_extent_buffer(leaf, buf,
4499 btrfs_item_ptr_offset(leaf, path->slots[0]),
4500 split_offset);
4501
4502 /* write the data for the new item */
4503 write_extent_buffer(leaf, buf + split_offset,
4504 btrfs_item_ptr_offset(leaf, slot),
4505 item_size - split_offset);
4506 btrfs_mark_buffer_dirty(leaf);
4507
4508 BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
4509 kfree(buf);
4510 return 0;
4511}
4512
4513/*
4514 * This function splits a single item into two items,
4515 * giving 'new_key' to the new item and splitting the
4516 * old one at split_offset (from the start of the item).
4517 *
4518 * The path may be released by this operation. After
4519 * the split, the path is pointing to the old item. The
4520 * new item is going to be in the same node as the old one.
4521 *
4522 * Note, the item being split must be smaller enough to live alone on
4523 * a tree block with room for one extra struct btrfs_item
4524 *
4525 * This allows us to split the item in place, keeping a lock on the
4526 * leaf the entire time.
4527 */
4528int btrfs_split_item(struct btrfs_trans_handle *trans,
4529 struct btrfs_root *root,
4530 struct btrfs_path *path,
4531 struct btrfs_key *new_key,
4532 unsigned long split_offset)
4533{
4534 int ret;
4535 ret = setup_leaf_for_split(trans, root, path,
4536 sizeof(struct btrfs_item));
4537 if (ret)
4538 return ret;
4539
4540 ret = split_item(trans, root, path, new_key, split_offset);
4541 return ret;
4542}
4543
4544/*
4545 * This function duplicate a item, giving 'new_key' to the new item.
4546 * It guarantees both items live in the same tree leaf and the new item
4547 * is contiguous with the original item.
4548 *
4549 * This allows us to split file extent in place, keeping a lock on the
4550 * leaf the entire time.
4551 */
4552int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4553 struct btrfs_root *root,
4554 struct btrfs_path *path,
4555 struct btrfs_key *new_key)
4556{
4557 struct extent_buffer *leaf;
4558 int ret;
4559 u32 item_size;
4560
4561 leaf = path->nodes[0];
4562 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4563 ret = setup_leaf_for_split(trans, root, path,
4564 item_size + sizeof(struct btrfs_item));
4565 if (ret)
4566 return ret;
4567
4568 path->slots[0]++;
4569 setup_items_for_insert(root, path, new_key, &item_size,
4570 item_size, item_size +
4571 sizeof(struct btrfs_item), 1);
4572 leaf = path->nodes[0];
4573 memcpy_extent_buffer(leaf,
4574 btrfs_item_ptr_offset(leaf, path->slots[0]),
4575 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4576 item_size);
4577 return 0;
4578}
4579
4580/*
4581 * make the item pointed to by the path smaller. new_size indicates
4582 * how small to make it, and from_end tells us if we just chop bytes
4583 * off the end of the item or if we shift the item to chop bytes off
4584 * the front.
4585 */
4586void btrfs_truncate_item(struct btrfs_root *root, struct btrfs_path *path,
4587 u32 new_size, int from_end)
4588{
4589 int slot;
4590 struct extent_buffer *leaf;
4591 struct btrfs_item *item;
4592 u32 nritems;
4593 unsigned int data_end;
4594 unsigned int old_data_start;
4595 unsigned int old_size;
4596 unsigned int size_diff;
4597 int i;
4598 struct btrfs_map_token token;
4599
4600 btrfs_init_map_token(&token);
4601
4602 leaf = path->nodes[0];
4603 slot = path->slots[0];
4604
4605 old_size = btrfs_item_size_nr(leaf, slot);
4606 if (old_size == new_size)
4607 return;
4608
4609 nritems = btrfs_header_nritems(leaf);
4610 data_end = leaf_data_end(root, leaf);
4611
4612 old_data_start = btrfs_item_offset_nr(leaf, slot);
4613
4614 size_diff = old_size - new_size;
4615
4616 BUG_ON(slot < 0);
4617 BUG_ON(slot >= nritems);
4618
4619 /*
4620 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4621 */
4622 /* first correct the data pointers */
4623 for (i = slot; i < nritems; i++) {
4624 u32 ioff;
4625 item = btrfs_item_nr(i);
4626
4627 ioff = btrfs_token_item_offset(leaf, item, &token);
4628 btrfs_set_token_item_offset(leaf, item,
4629 ioff + size_diff, &token);
4630 }
4631
4632 /* shift the data */
4633 if (from_end) {
4634 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4635 data_end + size_diff, btrfs_leaf_data(leaf) +
4636 data_end, old_data_start + new_size - data_end);
4637 } else {
4638 struct btrfs_disk_key disk_key;
4639 u64 offset;
4640
4641 btrfs_item_key(leaf, &disk_key, slot);
4642
4643 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4644 unsigned long ptr;
4645 struct btrfs_file_extent_item *fi;
4646
4647 fi = btrfs_item_ptr(leaf, slot,
4648 struct btrfs_file_extent_item);
4649 fi = (struct btrfs_file_extent_item *)(
4650 (unsigned long)fi - size_diff);
4651
4652 if (btrfs_file_extent_type(leaf, fi) ==
4653 BTRFS_FILE_EXTENT_INLINE) {
4654 ptr = btrfs_item_ptr_offset(leaf, slot);
4655 memmove_extent_buffer(leaf, ptr,
4656 (unsigned long)fi,
4657 offsetof(struct btrfs_file_extent_item,
4658 disk_bytenr));
4659 }
4660 }
4661
4662 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4663 data_end + size_diff, btrfs_leaf_data(leaf) +
4664 data_end, old_data_start - data_end);
4665
4666 offset = btrfs_disk_key_offset(&disk_key);
4667 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4668 btrfs_set_item_key(leaf, &disk_key, slot);
4669 if (slot == 0)
4670 fixup_low_keys(root, path, &disk_key, 1);
4671 }
4672
4673 item = btrfs_item_nr(slot);
4674 btrfs_set_item_size(leaf, item, new_size);
4675 btrfs_mark_buffer_dirty(leaf);
4676
4677 if (btrfs_leaf_free_space(root, leaf) < 0) {
4678 btrfs_print_leaf(root, leaf);
4679 BUG();
4680 }
4681}
4682
4683/*
4684 * make the item pointed to by the path bigger, data_size is the added size.
4685 */
4686void btrfs_extend_item(struct btrfs_root *root, struct btrfs_path *path,
4687 u32 data_size)
4688{
4689 int slot;
4690 struct extent_buffer *leaf;
4691 struct btrfs_item *item;
4692 u32 nritems;
4693 unsigned int data_end;
4694 unsigned int old_data;
4695 unsigned int old_size;
4696 int i;
4697 struct btrfs_map_token token;
4698
4699 btrfs_init_map_token(&token);
4700
4701 leaf = path->nodes[0];
4702
4703 nritems = btrfs_header_nritems(leaf);
4704 data_end = leaf_data_end(root, leaf);
4705
4706 if (btrfs_leaf_free_space(root, leaf) < data_size) {
4707 btrfs_print_leaf(root, leaf);
4708 BUG();
4709 }
4710 slot = path->slots[0];
4711 old_data = btrfs_item_end_nr(leaf, slot);
4712
4713 BUG_ON(slot < 0);
4714 if (slot >= nritems) {
4715 btrfs_print_leaf(root, leaf);
4716 btrfs_crit(root->fs_info, "slot %d too large, nritems %d",
4717 slot, nritems);
4718 BUG_ON(1);
4719 }
4720
4721 /*
4722 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4723 */
4724 /* first correct the data pointers */
4725 for (i = slot; i < nritems; i++) {
4726 u32 ioff;
4727 item = btrfs_item_nr(i);
4728
4729 ioff = btrfs_token_item_offset(leaf, item, &token);
4730 btrfs_set_token_item_offset(leaf, item,
4731 ioff - data_size, &token);
4732 }
4733
4734 /* shift the data */
4735 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4736 data_end - data_size, btrfs_leaf_data(leaf) +
4737 data_end, old_data - data_end);
4738
4739 data_end = old_data;
4740 old_size = btrfs_item_size_nr(leaf, slot);
4741 item = btrfs_item_nr(slot);
4742 btrfs_set_item_size(leaf, item, old_size + data_size);
4743 btrfs_mark_buffer_dirty(leaf);
4744
4745 if (btrfs_leaf_free_space(root, leaf) < 0) {
4746 btrfs_print_leaf(root, leaf);
4747 BUG();
4748 }
4749}
4750
4751/*
4752 * this is a helper for btrfs_insert_empty_items, the main goal here is
4753 * to save stack depth by doing the bulk of the work in a function
4754 * that doesn't call btrfs_search_slot
4755 */
4756void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
4757 struct btrfs_key *cpu_key, u32 *data_size,
4758 u32 total_data, u32 total_size, int nr)
4759{
4760 struct btrfs_item *item;
4761 int i;
4762 u32 nritems;
4763 unsigned int data_end;
4764 struct btrfs_disk_key disk_key;
4765 struct extent_buffer *leaf;
4766 int slot;
4767 struct btrfs_map_token token;
4768
4769 btrfs_init_map_token(&token);
4770
4771 leaf = path->nodes[0];
4772 slot = path->slots[0];
4773
4774 nritems = btrfs_header_nritems(leaf);
4775 data_end = leaf_data_end(root, leaf);
4776
4777 if (btrfs_leaf_free_space(root, leaf) < total_size) {
4778 btrfs_print_leaf(root, leaf);
4779 btrfs_crit(root->fs_info, "not enough freespace need %u have %d",
4780 total_size, btrfs_leaf_free_space(root, leaf));
4781 BUG();
4782 }
4783
4784 if (slot != nritems) {
4785 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4786
4787 if (old_data < data_end) {
4788 btrfs_print_leaf(root, leaf);
4789 btrfs_crit(root->fs_info, "slot %d old_data %d data_end %d",
4790 slot, old_data, data_end);
4791 BUG_ON(1);
4792 }
4793 /*
4794 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4795 */
4796 /* first correct the data pointers */
4797 for (i = slot; i < nritems; i++) {
4798 u32 ioff;
4799
4800 item = btrfs_item_nr( i);
4801 ioff = btrfs_token_item_offset(leaf, item, &token);
4802 btrfs_set_token_item_offset(leaf, item,
4803 ioff - total_data, &token);
4804 }
4805 /* shift the items */
4806 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4807 btrfs_item_nr_offset(slot),
4808 (nritems - slot) * sizeof(struct btrfs_item));
4809
4810 /* shift the data */
4811 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4812 data_end - total_data, btrfs_leaf_data(leaf) +
4813 data_end, old_data - data_end);
4814 data_end = old_data;
4815 }
4816
4817 /* setup the item for the new data */
4818 for (i = 0; i < nr; i++) {
4819 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4820 btrfs_set_item_key(leaf, &disk_key, slot + i);
4821 item = btrfs_item_nr(slot + i);
4822 btrfs_set_token_item_offset(leaf, item,
4823 data_end - data_size[i], &token);
4824 data_end -= data_size[i];
4825 btrfs_set_token_item_size(leaf, item, data_size[i], &token);
4826 }
4827
4828 btrfs_set_header_nritems(leaf, nritems + nr);
4829
4830 if (slot == 0) {
4831 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4832 fixup_low_keys(root, path, &disk_key, 1);
4833 }
4834 btrfs_unlock_up_safe(path, 1);
4835 btrfs_mark_buffer_dirty(leaf);
4836
4837 if (btrfs_leaf_free_space(root, leaf) < 0) {
4838 btrfs_print_leaf(root, leaf);
4839 BUG();
4840 }
4841}
4842
4843/*
4844 * Given a key and some data, insert items into the tree.
4845 * This does all the path init required, making room in the tree if needed.
4846 */
4847int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4848 struct btrfs_root *root,
4849 struct btrfs_path *path,
4850 struct btrfs_key *cpu_key, u32 *data_size,
4851 int nr)
4852{
4853 int ret = 0;
4854 int slot;
4855 int i;
4856 u32 total_size = 0;
4857 u32 total_data = 0;
4858
4859 for (i = 0; i < nr; i++)
4860 total_data += data_size[i];
4861
4862 total_size = total_data + (nr * sizeof(struct btrfs_item));
4863 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4864 if (ret == 0)
4865 return -EEXIST;
4866 if (ret < 0)
4867 return ret;
4868
4869 slot = path->slots[0];
4870 BUG_ON(slot < 0);
4871
4872 setup_items_for_insert(root, path, cpu_key, data_size,
4873 total_data, total_size, nr);
4874 return 0;
4875}
4876
4877/*
4878 * Given a key and some data, insert an item into the tree.
4879 * This does all the path init required, making room in the tree if needed.
4880 */
4881int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
4882 *root, struct btrfs_key *cpu_key, void *data, u32
4883 data_size)
4884{
4885 int ret = 0;
4886 struct btrfs_path *path;
4887 struct extent_buffer *leaf;
4888 unsigned long ptr;
4889
4890 path = btrfs_alloc_path();
4891 if (!path)
4892 return -ENOMEM;
4893 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4894 if (!ret) {
4895 leaf = path->nodes[0];
4896 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4897 write_extent_buffer(leaf, data, ptr, data_size);
4898 btrfs_mark_buffer_dirty(leaf);
4899 }
4900 btrfs_free_path(path);
4901 return ret;
4902}
4903
4904/*
4905 * delete the pointer from a given node.
4906 *
4907 * the tree should have been previously balanced so the deletion does not
4908 * empty a node.
4909 */
4910static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
4911 int level, int slot)
4912{
4913 struct extent_buffer *parent = path->nodes[level];
4914 u32 nritems;
4915 int ret;
4916
4917 nritems = btrfs_header_nritems(parent);
4918 if (slot != nritems - 1) {
4919 if (level)
4920 tree_mod_log_eb_move(root->fs_info, parent, slot,
4921 slot + 1, nritems - slot - 1);
4922 memmove_extent_buffer(parent,
4923 btrfs_node_key_ptr_offset(slot),
4924 btrfs_node_key_ptr_offset(slot + 1),
4925 sizeof(struct btrfs_key_ptr) *
4926 (nritems - slot - 1));
4927 } else if (level) {
4928 ret = tree_mod_log_insert_key(root->fs_info, parent, slot,
4929 MOD_LOG_KEY_REMOVE, GFP_NOFS);
4930 BUG_ON(ret < 0);
4931 }
4932
4933 nritems--;
4934 btrfs_set_header_nritems(parent, nritems);
4935 if (nritems == 0 && parent == root->node) {
4936 BUG_ON(btrfs_header_level(root->node) != 1);
4937 /* just turn the root into a leaf and break */
4938 btrfs_set_header_level(root->node, 0);
4939 } else if (slot == 0) {
4940 struct btrfs_disk_key disk_key;
4941
4942 btrfs_node_key(parent, &disk_key, 0);
4943 fixup_low_keys(root, path, &disk_key, level + 1);
4944 }
4945 btrfs_mark_buffer_dirty(parent);
4946}
4947
4948/*
4949 * a helper function to delete the leaf pointed to by path->slots[1] and
4950 * path->nodes[1].
4951 *
4952 * This deletes the pointer in path->nodes[1] and frees the leaf
4953 * block extent. zero is returned if it all worked out, < 0 otherwise.
4954 *
4955 * The path must have already been setup for deleting the leaf, including
4956 * all the proper balancing. path->nodes[1] must be locked.
4957 */
4958static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4959 struct btrfs_root *root,
4960 struct btrfs_path *path,
4961 struct extent_buffer *leaf)
4962{
4963 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4964 del_ptr(root, path, 1, path->slots[1]);
4965
4966 /*
4967 * btrfs_free_extent is expensive, we want to make sure we
4968 * aren't holding any locks when we call it
4969 */
4970 btrfs_unlock_up_safe(path, 0);
4971
4972 root_sub_used(root, leaf->len);
4973
4974 extent_buffer_get(leaf);
4975 btrfs_free_tree_block(trans, root, leaf, 0, 1);
4976 free_extent_buffer_stale(leaf);
4977}
4978/*
4979 * delete the item at the leaf level in path. If that empties
4980 * the leaf, remove it from the tree
4981 */
4982int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4983 struct btrfs_path *path, int slot, int nr)
4984{
4985 struct extent_buffer *leaf;
4986 struct btrfs_item *item;
4987 int last_off;
4988 int dsize = 0;
4989 int ret = 0;
4990 int wret;
4991 int i;
4992 u32 nritems;
4993 struct btrfs_map_token token;
4994
4995 btrfs_init_map_token(&token);
4996
4997 leaf = path->nodes[0];
4998 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4999
5000 for (i = 0; i < nr; i++)
5001 dsize += btrfs_item_size_nr(leaf, slot + i);
5002
5003 nritems = btrfs_header_nritems(leaf);
5004
5005 if (slot + nr != nritems) {
5006 int data_end = leaf_data_end(root, leaf);
5007
5008 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
5009 data_end + dsize,
5010 btrfs_leaf_data(leaf) + data_end,
5011 last_off - data_end);
5012
5013 for (i = slot + nr; i < nritems; i++) {
5014 u32 ioff;
5015
5016 item = btrfs_item_nr(i);
5017 ioff = btrfs_token_item_offset(leaf, item, &token);
5018 btrfs_set_token_item_offset(leaf, item,
5019 ioff + dsize, &token);
5020 }
5021
5022 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
5023 btrfs_item_nr_offset(slot + nr),
5024 sizeof(struct btrfs_item) *
5025 (nritems - slot - nr));
5026 }
5027 btrfs_set_header_nritems(leaf, nritems - nr);
5028 nritems -= nr;
5029
5030 /* delete the leaf if we've emptied it */
5031 if (nritems == 0) {
5032 if (leaf == root->node) {
5033 btrfs_set_header_level(leaf, 0);
5034 } else {
5035 btrfs_set_path_blocking(path);
5036 clean_tree_block(trans, root, leaf);
5037 btrfs_del_leaf(trans, root, path, leaf);
5038 }
5039 } else {
5040 int used = leaf_space_used(leaf, 0, nritems);
5041 if (slot == 0) {
5042 struct btrfs_disk_key disk_key;
5043
5044 btrfs_item_key(leaf, &disk_key, 0);
5045 fixup_low_keys(root, path, &disk_key, 1);
5046 }
5047
5048 /* delete the leaf if it is mostly empty */
5049 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
5050 /* push_leaf_left fixes the path.
5051 * make sure the path still points to our leaf
5052 * for possible call to del_ptr below
5053 */
5054 slot = path->slots[1];
5055 extent_buffer_get(leaf);
5056
5057 btrfs_set_path_blocking(path);
5058 wret = push_leaf_left(trans, root, path, 1, 1,
5059 1, (u32)-1);
5060 if (wret < 0 && wret != -ENOSPC)
5061 ret = wret;
5062
5063 if (path->nodes[0] == leaf &&
5064 btrfs_header_nritems(leaf)) {
5065 wret = push_leaf_right(trans, root, path, 1,
5066 1, 1, 0);
5067 if (wret < 0 && wret != -ENOSPC)
5068 ret = wret;
5069 }
5070
5071 if (btrfs_header_nritems(leaf) == 0) {
5072 path->slots[1] = slot;
5073 btrfs_del_leaf(trans, root, path, leaf);
5074 free_extent_buffer(leaf);
5075 ret = 0;
5076 } else {
5077 /* if we're still in the path, make sure
5078 * we're dirty. Otherwise, one of the
5079 * push_leaf functions must have already
5080 * dirtied this buffer
5081 */
5082 if (path->nodes[0] == leaf)
5083 btrfs_mark_buffer_dirty(leaf);
5084 free_extent_buffer(leaf);
5085 }
5086 } else {
5087 btrfs_mark_buffer_dirty(leaf);
5088 }
5089 }
5090 return ret;
5091}
5092
5093/*
5094 * search the tree again to find a leaf with lesser keys
5095 * returns 0 if it found something or 1 if there are no lesser leaves.
5096 * returns < 0 on io errors.
5097 *
5098 * This may release the path, and so you may lose any locks held at the
5099 * time you call it.
5100 */
5101int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
5102{
5103 struct btrfs_key key;
5104 struct btrfs_disk_key found_key;
5105 int ret;
5106
5107 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
5108
5109 if (key.offset > 0) {
5110 key.offset--;
5111 } else if (key.type > 0) {
5112 key.type--;
5113 key.offset = (u64)-1;
5114 } else if (key.objectid > 0) {
5115 key.objectid--;
5116 key.type = (u8)-1;
5117 key.offset = (u64)-1;
5118 } else {
5119 return 1;
5120 }
5121
5122 btrfs_release_path(path);
5123 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5124 if (ret < 0)
5125 return ret;
5126 btrfs_item_key(path->nodes[0], &found_key, 0);
5127 ret = comp_keys(&found_key, &key);
5128 if (ret < 0)
5129 return 0;
5130 return 1;
5131}
5132
5133/*
5134 * A helper function to walk down the tree starting at min_key, and looking
5135 * for nodes or leaves that are have a minimum transaction id.
5136 * This is used by the btree defrag code, and tree logging
5137 *
5138 * This does not cow, but it does stuff the starting key it finds back
5139 * into min_key, so you can call btrfs_search_slot with cow=1 on the
5140 * key and get a writable path.
5141 *
5142 * This does lock as it descends, and path->keep_locks should be set
5143 * to 1 by the caller.
5144 *
5145 * This honors path->lowest_level to prevent descent past a given level
5146 * of the tree.
5147 *
5148 * min_trans indicates the oldest transaction that you are interested
5149 * in walking through. Any nodes or leaves older than min_trans are
5150 * skipped over (without reading them).
5151 *
5152 * returns zero if something useful was found, < 0 on error and 1 if there
5153 * was nothing in the tree that matched the search criteria.
5154 */
5155int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
5156 struct btrfs_path *path,
5157 u64 min_trans)
5158{
5159 struct extent_buffer *cur;
5160 struct btrfs_key found_key;
5161 int slot;
5162 int sret;
5163 u32 nritems;
5164 int level;
5165 int ret = 1;
5166
5167 WARN_ON(!path->keep_locks);
5168again:
5169 cur = btrfs_read_lock_root_node(root);
5170 level = btrfs_header_level(cur);
5171 WARN_ON(path->nodes[level]);
5172 path->nodes[level] = cur;
5173 path->locks[level] = BTRFS_READ_LOCK;
5174
5175 if (btrfs_header_generation(cur) < min_trans) {
5176 ret = 1;
5177 goto out;
5178 }
5179 while (1) {
5180 nritems = btrfs_header_nritems(cur);
5181 level = btrfs_header_level(cur);
5182 sret = bin_search(cur, min_key, level, &slot);
5183
5184 /* at the lowest level, we're done, setup the path and exit */
5185 if (level == path->lowest_level) {
5186 if (slot >= nritems)
5187 goto find_next_key;
5188 ret = 0;
5189 path->slots[level] = slot;
5190 btrfs_item_key_to_cpu(cur, &found_key, slot);
5191 goto out;
5192 }
5193 if (sret && slot > 0)
5194 slot--;
5195 /*
5196 * check this node pointer against the min_trans parameters.
5197 * If it is too old, old, skip to the next one.
5198 */
5199 while (slot < nritems) {
5200 u64 gen;
5201
5202 gen = btrfs_node_ptr_generation(cur, slot);
5203 if (gen < min_trans) {
5204 slot++;
5205 continue;
5206 }
5207 break;
5208 }
5209find_next_key:
5210 /*
5211 * we didn't find a candidate key in this node, walk forward
5212 * and find another one
5213 */
5214 if (slot >= nritems) {
5215 path->slots[level] = slot;
5216 btrfs_set_path_blocking(path);
5217 sret = btrfs_find_next_key(root, path, min_key, level,
5218 min_trans);
5219 if (sret == 0) {
5220 btrfs_release_path(path);
5221 goto again;
5222 } else {
5223 goto out;
5224 }
5225 }
5226 /* save our key for returning back */
5227 btrfs_node_key_to_cpu(cur, &found_key, slot);
5228 path->slots[level] = slot;
5229 if (level == path->lowest_level) {
5230 ret = 0;
5231 unlock_up(path, level, 1, 0, NULL);
5232 goto out;
5233 }
5234 btrfs_set_path_blocking(path);
5235 cur = read_node_slot(root, cur, slot);
5236 BUG_ON(!cur); /* -ENOMEM */
5237
5238 btrfs_tree_read_lock(cur);
5239
5240 path->locks[level - 1] = BTRFS_READ_LOCK;
5241 path->nodes[level - 1] = cur;
5242 unlock_up(path, level, 1, 0, NULL);
5243 btrfs_clear_path_blocking(path, NULL, 0);
5244 }
5245out:
5246 if (ret == 0)
5247 memcpy(min_key, &found_key, sizeof(found_key));
5248 btrfs_set_path_blocking(path);
5249 return ret;
5250}
5251
5252static void tree_move_down(struct btrfs_root *root,
5253 struct btrfs_path *path,
5254 int *level, int root_level)
5255{
5256 BUG_ON(*level == 0);
5257 path->nodes[*level - 1] = read_node_slot(root, path->nodes[*level],
5258 path->slots[*level]);
5259 path->slots[*level - 1] = 0;
5260 (*level)--;
5261}
5262
5263static int tree_move_next_or_upnext(struct btrfs_root *root,
5264 struct btrfs_path *path,
5265 int *level, int root_level)
5266{
5267 int ret = 0;
5268 int nritems;
5269 nritems = btrfs_header_nritems(path->nodes[*level]);
5270
5271 path->slots[*level]++;
5272
5273 while (path->slots[*level] >= nritems) {
5274 if (*level == root_level)
5275 return -1;
5276
5277 /* move upnext */
5278 path->slots[*level] = 0;
5279 free_extent_buffer(path->nodes[*level]);
5280 path->nodes[*level] = NULL;
5281 (*level)++;
5282 path->slots[*level]++;
5283
5284 nritems = btrfs_header_nritems(path->nodes[*level]);
5285 ret = 1;
5286 }
5287 return ret;
5288}
5289
5290/*
5291 * Returns 1 if it had to move up and next. 0 is returned if it moved only next
5292 * or down.
5293 */
5294static int tree_advance(struct btrfs_root *root,
5295 struct btrfs_path *path,
5296 int *level, int root_level,
5297 int allow_down,
5298 struct btrfs_key *key)
5299{
5300 int ret;
5301
5302 if (*level == 0 || !allow_down) {
5303 ret = tree_move_next_or_upnext(root, path, level, root_level);
5304 } else {
5305 tree_move_down(root, path, level, root_level);
5306 ret = 0;
5307 }
5308 if (ret >= 0) {
5309 if (*level == 0)
5310 btrfs_item_key_to_cpu(path->nodes[*level], key,
5311 path->slots[*level]);
5312 else
5313 btrfs_node_key_to_cpu(path->nodes[*level], key,
5314 path->slots[*level]);
5315 }
5316 return ret;
5317}
5318
5319static int tree_compare_item(struct btrfs_root *left_root,
5320 struct btrfs_path *left_path,
5321 struct btrfs_path *right_path,
5322 char *tmp_buf)
5323{
5324 int cmp;
5325 int len1, len2;
5326 unsigned long off1, off2;
5327
5328 len1 = btrfs_item_size_nr(left_path->nodes[0], left_path->slots[0]);
5329 len2 = btrfs_item_size_nr(right_path->nodes[0], right_path->slots[0]);
5330 if (len1 != len2)
5331 return 1;
5332
5333 off1 = btrfs_item_ptr_offset(left_path->nodes[0], left_path->slots[0]);
5334 off2 = btrfs_item_ptr_offset(right_path->nodes[0],
5335 right_path->slots[0]);
5336
5337 read_extent_buffer(left_path->nodes[0], tmp_buf, off1, len1);
5338
5339 cmp = memcmp_extent_buffer(right_path->nodes[0], tmp_buf, off2, len1);
5340 if (cmp)
5341 return 1;
5342 return 0;
5343}
5344
5345#define ADVANCE 1
5346#define ADVANCE_ONLY_NEXT -1
5347
5348/*
5349 * This function compares two trees and calls the provided callback for
5350 * every changed/new/deleted item it finds.
5351 * If shared tree blocks are encountered, whole subtrees are skipped, making
5352 * the compare pretty fast on snapshotted subvolumes.
5353 *
5354 * This currently works on commit roots only. As commit roots are read only,
5355 * we don't do any locking. The commit roots are protected with transactions.
5356 * Transactions are ended and rejoined when a commit is tried in between.
5357 *
5358 * This function checks for modifications done to the trees while comparing.
5359 * If it detects a change, it aborts immediately.
5360 */
5361int btrfs_compare_trees(struct btrfs_root *left_root,
5362 struct btrfs_root *right_root,
5363 btrfs_changed_cb_t changed_cb, void *ctx)
5364{
5365 int ret;
5366 int cmp;
5367 struct btrfs_path *left_path = NULL;
5368 struct btrfs_path *right_path = NULL;
5369 struct btrfs_key left_key;
5370 struct btrfs_key right_key;
5371 char *tmp_buf = NULL;
5372 int left_root_level;
5373 int right_root_level;
5374 int left_level;
5375 int right_level;
5376 int left_end_reached;
5377 int right_end_reached;
5378 int advance_left;
5379 int advance_right;
5380 u64 left_blockptr;
5381 u64 right_blockptr;
5382 u64 left_gen;
5383 u64 right_gen;
5384
5385 left_path = btrfs_alloc_path();
5386 if (!left_path) {
5387 ret = -ENOMEM;
5388 goto out;
5389 }
5390 right_path = btrfs_alloc_path();
5391 if (!right_path) {
5392 ret = -ENOMEM;
5393 goto out;
5394 }
5395
5396 tmp_buf = kmalloc(left_root->leafsize, GFP_NOFS);
5397 if (!tmp_buf) {
5398 ret = -ENOMEM;
5399 goto out;
5400 }
5401
5402 left_path->search_commit_root = 1;
5403 left_path->skip_locking = 1;
5404 right_path->search_commit_root = 1;
5405 right_path->skip_locking = 1;
5406
5407 /*
5408 * Strategy: Go to the first items of both trees. Then do
5409 *
5410 * If both trees are at level 0
5411 * Compare keys of current items
5412 * If left < right treat left item as new, advance left tree
5413 * and repeat
5414 * If left > right treat right item as deleted, advance right tree
5415 * and repeat
5416 * If left == right do deep compare of items, treat as changed if
5417 * needed, advance both trees and repeat
5418 * If both trees are at the same level but not at level 0
5419 * Compare keys of current nodes/leafs
5420 * If left < right advance left tree and repeat
5421 * If left > right advance right tree and repeat
5422 * If left == right compare blockptrs of the next nodes/leafs
5423 * If they match advance both trees but stay at the same level
5424 * and repeat
5425 * If they don't match advance both trees while allowing to go
5426 * deeper and repeat
5427 * If tree levels are different
5428 * Advance the tree that needs it and repeat
5429 *
5430 * Advancing a tree means:
5431 * If we are at level 0, try to go to the next slot. If that's not
5432 * possible, go one level up and repeat. Stop when we found a level
5433 * where we could go to the next slot. We may at this point be on a
5434 * node or a leaf.
5435 *
5436 * If we are not at level 0 and not on shared tree blocks, go one
5437 * level deeper.
5438 *
5439 * If we are not at level 0 and on shared tree blocks, go one slot to
5440 * the right if possible or go up and right.
5441 */
5442
5443 down_read(&left_root->fs_info->commit_root_sem);
5444 left_level = btrfs_header_level(left_root->commit_root);
5445 left_root_level = left_level;
5446 left_path->nodes[left_level] = left_root->commit_root;
5447 extent_buffer_get(left_path->nodes[left_level]);
5448
5449 right_level = btrfs_header_level(right_root->commit_root);
5450 right_root_level = right_level;
5451 right_path->nodes[right_level] = right_root->commit_root;
5452 extent_buffer_get(right_path->nodes[right_level]);
5453 up_read(&left_root->fs_info->commit_root_sem);
5454
5455 if (left_level == 0)
5456 btrfs_item_key_to_cpu(left_path->nodes[left_level],
5457 &left_key, left_path->slots[left_level]);
5458 else
5459 btrfs_node_key_to_cpu(left_path->nodes[left_level],
5460 &left_key, left_path->slots[left_level]);
5461 if (right_level == 0)
5462 btrfs_item_key_to_cpu(right_path->nodes[right_level],
5463 &right_key, right_path->slots[right_level]);
5464 else
5465 btrfs_node_key_to_cpu(right_path->nodes[right_level],
5466 &right_key, right_path->slots[right_level]);
5467
5468 left_end_reached = right_end_reached = 0;
5469 advance_left = advance_right = 0;
5470
5471 while (1) {
5472 if (advance_left && !left_end_reached) {
5473 ret = tree_advance(left_root, left_path, &left_level,
5474 left_root_level,
5475 advance_left != ADVANCE_ONLY_NEXT,
5476 &left_key);
5477 if (ret < 0)
5478 left_end_reached = ADVANCE;
5479 advance_left = 0;
5480 }
5481 if (advance_right && !right_end_reached) {
5482 ret = tree_advance(right_root, right_path, &right_level,
5483 right_root_level,
5484 advance_right != ADVANCE_ONLY_NEXT,
5485 &right_key);
5486 if (ret < 0)
5487 right_end_reached = ADVANCE;
5488 advance_right = 0;
5489 }
5490
5491 if (left_end_reached && right_end_reached) {
5492 ret = 0;
5493 goto out;
5494 } else if (left_end_reached) {
5495 if (right_level == 0) {
5496 ret = changed_cb(left_root, right_root,
5497 left_path, right_path,
5498 &right_key,
5499 BTRFS_COMPARE_TREE_DELETED,
5500 ctx);
5501 if (ret < 0)
5502 goto out;
5503 }
5504 advance_right = ADVANCE;
5505 continue;
5506 } else if (right_end_reached) {
5507 if (left_level == 0) {
5508 ret = changed_cb(left_root, right_root,
5509 left_path, right_path,
5510 &left_key,
5511 BTRFS_COMPARE_TREE_NEW,
5512 ctx);
5513 if (ret < 0)
5514 goto out;
5515 }
5516 advance_left = ADVANCE;
5517 continue;
5518 }
5519
5520 if (left_level == 0 && right_level == 0) {
5521 cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
5522 if (cmp < 0) {
5523 ret = changed_cb(left_root, right_root,
5524 left_path, right_path,
5525 &left_key,
5526 BTRFS_COMPARE_TREE_NEW,
5527 ctx);
5528 if (ret < 0)
5529 goto out;
5530 advance_left = ADVANCE;
5531 } else if (cmp > 0) {
5532 ret = changed_cb(left_root, right_root,
5533 left_path, right_path,
5534 &right_key,
5535 BTRFS_COMPARE_TREE_DELETED,
5536 ctx);
5537 if (ret < 0)
5538 goto out;
5539 advance_right = ADVANCE;
5540 } else {
5541 enum btrfs_compare_tree_result cmp;
5542
5543 WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
5544 ret = tree_compare_item(left_root, left_path,
5545 right_path, tmp_buf);
5546 if (ret)
5547 cmp = BTRFS_COMPARE_TREE_CHANGED;
5548 else
5549 cmp = BTRFS_COMPARE_TREE_SAME;
5550 ret = changed_cb(left_root, right_root,
5551 left_path, right_path,
5552 &left_key, cmp, ctx);
5553 if (ret < 0)
5554 goto out;
5555 advance_left = ADVANCE;
5556 advance_right = ADVANCE;
5557 }
5558 } else if (left_level == right_level) {
5559 cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
5560 if (cmp < 0) {
5561 advance_left = ADVANCE;
5562 } else if (cmp > 0) {
5563 advance_right = ADVANCE;
5564 } else {
5565 left_blockptr = btrfs_node_blockptr(
5566 left_path->nodes[left_level],
5567 left_path->slots[left_level]);
5568 right_blockptr = btrfs_node_blockptr(
5569 right_path->nodes[right_level],
5570 right_path->slots[right_level]);
5571 left_gen = btrfs_node_ptr_generation(
5572 left_path->nodes[left_level],
5573 left_path->slots[left_level]);
5574 right_gen = btrfs_node_ptr_generation(
5575 right_path->nodes[right_level],
5576 right_path->slots[right_level]);
5577 if (left_blockptr == right_blockptr &&
5578 left_gen == right_gen) {
5579 /*
5580 * As we're on a shared block, don't
5581 * allow to go deeper.
5582 */
5583 advance_left = ADVANCE_ONLY_NEXT;
5584 advance_right = ADVANCE_ONLY_NEXT;
5585 } else {
5586 advance_left = ADVANCE;
5587 advance_right = ADVANCE;
5588 }
5589 }
5590 } else if (left_level < right_level) {
5591 advance_right = ADVANCE;
5592 } else {
5593 advance_left = ADVANCE;
5594 }
5595 }
5596
5597out:
5598 btrfs_free_path(left_path);
5599 btrfs_free_path(right_path);
5600 kfree(tmp_buf);
5601 return ret;
5602}
5603
5604/*
5605 * this is similar to btrfs_next_leaf, but does not try to preserve
5606 * and fixup the path. It looks for and returns the next key in the
5607 * tree based on the current path and the min_trans parameters.
5608 *
5609 * 0 is returned if another key is found, < 0 if there are any errors
5610 * and 1 is returned if there are no higher keys in the tree
5611 *
5612 * path->keep_locks should be set to 1 on the search made before
5613 * calling this function.
5614 */
5615int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
5616 struct btrfs_key *key, int level, u64 min_trans)
5617{
5618 int slot;
5619 struct extent_buffer *c;
5620
5621 WARN_ON(!path->keep_locks);
5622 while (level < BTRFS_MAX_LEVEL) {
5623 if (!path->nodes[level])
5624 return 1;
5625
5626 slot = path->slots[level] + 1;
5627 c = path->nodes[level];
5628next:
5629 if (slot >= btrfs_header_nritems(c)) {
5630 int ret;
5631 int orig_lowest;
5632 struct btrfs_key cur_key;
5633 if (level + 1 >= BTRFS_MAX_LEVEL ||
5634 !path->nodes[level + 1])
5635 return 1;
5636
5637 if (path->locks[level + 1]) {
5638 level++;
5639 continue;
5640 }
5641
5642 slot = btrfs_header_nritems(c) - 1;
5643 if (level == 0)
5644 btrfs_item_key_to_cpu(c, &cur_key, slot);
5645 else
5646 btrfs_node_key_to_cpu(c, &cur_key, slot);
5647
5648 orig_lowest = path->lowest_level;
5649 btrfs_release_path(path);
5650 path->lowest_level = level;
5651 ret = btrfs_search_slot(NULL, root, &cur_key, path,
5652 0, 0);
5653 path->lowest_level = orig_lowest;
5654 if (ret < 0)
5655 return ret;
5656
5657 c = path->nodes[level];
5658 slot = path->slots[level];
5659 if (ret == 0)
5660 slot++;
5661 goto next;
5662 }
5663
5664 if (level == 0)
5665 btrfs_item_key_to_cpu(c, key, slot);
5666 else {
5667 u64 gen = btrfs_node_ptr_generation(c, slot);
5668
5669 if (gen < min_trans) {
5670 slot++;
5671 goto next;
5672 }
5673 btrfs_node_key_to_cpu(c, key, slot);
5674 }
5675 return 0;
5676 }
5677 return 1;
5678}
5679
5680/*
5681 * search the tree again to find a leaf with greater keys
5682 * returns 0 if it found something or 1 if there are no greater leaves.
5683 * returns < 0 on io errors.
5684 */
5685int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
5686{
5687 return btrfs_next_old_leaf(root, path, 0);
5688}
5689
5690int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
5691 u64 time_seq)
5692{
5693 int slot;
5694 int level;
5695 struct extent_buffer *c;
5696 struct extent_buffer *next;
5697 struct btrfs_key key;
5698 u32 nritems;
5699 int ret;
5700 int old_spinning = path->leave_spinning;
5701 int next_rw_lock = 0;
5702
5703 nritems = btrfs_header_nritems(path->nodes[0]);
5704 if (nritems == 0)
5705 return 1;
5706
5707 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5708again:
5709 level = 1;
5710 next = NULL;
5711 next_rw_lock = 0;
5712 btrfs_release_path(path);
5713
5714 path->keep_locks = 1;
5715 path->leave_spinning = 1;
5716
5717 if (time_seq)
5718 ret = btrfs_search_old_slot(root, &key, path, time_seq);
5719 else
5720 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5721 path->keep_locks = 0;
5722
5723 if (ret < 0)
5724 return ret;
5725
5726 nritems = btrfs_header_nritems(path->nodes[0]);
5727 /*
5728 * by releasing the path above we dropped all our locks. A balance
5729 * could have added more items next to the key that used to be
5730 * at the very end of the block. So, check again here and
5731 * advance the path if there are now more items available.
5732 */
5733 if (nritems > 0 && path->slots[0] < nritems - 1) {
5734 if (ret == 0)
5735 path->slots[0]++;
5736 ret = 0;
5737 goto done;
5738 }
5739
5740 while (level < BTRFS_MAX_LEVEL) {
5741 if (!path->nodes[level]) {
5742 ret = 1;
5743 goto done;
5744 }
5745
5746 slot = path->slots[level] + 1;
5747 c = path->nodes[level];
5748 if (slot >= btrfs_header_nritems(c)) {
5749 level++;
5750 if (level == BTRFS_MAX_LEVEL) {
5751 ret = 1;
5752 goto done;
5753 }
5754 continue;
5755 }
5756
5757 if (next) {
5758 btrfs_tree_unlock_rw(next, next_rw_lock);
5759 free_extent_buffer(next);
5760 }
5761
5762 next = c;
5763 next_rw_lock = path->locks[level];
5764 ret = read_block_for_search(NULL, root, path, &next, level,
5765 slot, &key, 0);
5766 if (ret == -EAGAIN)
5767 goto again;
5768
5769 if (ret < 0) {
5770 btrfs_release_path(path);
5771 goto done;
5772 }
5773
5774 if (!path->skip_locking) {
5775 ret = btrfs_try_tree_read_lock(next);
5776 if (!ret && time_seq) {
5777 /*
5778 * If we don't get the lock, we may be racing
5779 * with push_leaf_left, holding that lock while
5780 * itself waiting for the leaf we've currently
5781 * locked. To solve this situation, we give up
5782 * on our lock and cycle.
5783 */
5784 free_extent_buffer(next);
5785 btrfs_release_path(path);
5786 cond_resched();
5787 goto again;
5788 }
5789 if (!ret) {
5790 btrfs_set_path_blocking(path);
5791 btrfs_tree_read_lock(next);
5792 btrfs_clear_path_blocking(path, next,
5793 BTRFS_READ_LOCK);
5794 }
5795 next_rw_lock = BTRFS_READ_LOCK;
5796 }
5797 break;
5798 }
5799 path->slots[level] = slot;
5800 while (1) {
5801 level--;
5802 c = path->nodes[level];
5803 if (path->locks[level])
5804 btrfs_tree_unlock_rw(c, path->locks[level]);
5805
5806 free_extent_buffer(c);
5807 path->nodes[level] = next;
5808 path->slots[level] = 0;
5809 if (!path->skip_locking)
5810 path->locks[level] = next_rw_lock;
5811 if (!level)
5812 break;
5813
5814 ret = read_block_for_search(NULL, root, path, &next, level,
5815 0, &key, 0);
5816 if (ret == -EAGAIN)
5817 goto again;
5818
5819 if (ret < 0) {
5820 btrfs_release_path(path);
5821 goto done;
5822 }
5823
5824 if (!path->skip_locking) {
5825 ret = btrfs_try_tree_read_lock(next);
5826 if (!ret) {
5827 btrfs_set_path_blocking(path);
5828 btrfs_tree_read_lock(next);
5829 btrfs_clear_path_blocking(path, next,
5830 BTRFS_READ_LOCK);
5831 }
5832 next_rw_lock = BTRFS_READ_LOCK;
5833 }
5834 }
5835 ret = 0;
5836done:
5837 unlock_up(path, 0, 1, 0, NULL);
5838 path->leave_spinning = old_spinning;
5839 if (!old_spinning)
5840 btrfs_set_path_blocking(path);
5841
5842 return ret;
5843}
5844
5845/*
5846 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5847 * searching until it gets past min_objectid or finds an item of 'type'
5848 *
5849 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5850 */
5851int btrfs_previous_item(struct btrfs_root *root,
5852 struct btrfs_path *path, u64 min_objectid,
5853 int type)
5854{
5855 struct btrfs_key found_key;
5856 struct extent_buffer *leaf;
5857 u32 nritems;
5858 int ret;
5859
5860 while (1) {
5861 if (path->slots[0] == 0) {
5862 btrfs_set_path_blocking(path);
5863 ret = btrfs_prev_leaf(root, path);
5864 if (ret != 0)
5865 return ret;
5866 } else {
5867 path->slots[0]--;
5868 }
5869 leaf = path->nodes[0];
5870 nritems = btrfs_header_nritems(leaf);
5871 if (nritems == 0)
5872 return 1;
5873 if (path->slots[0] == nritems)
5874 path->slots[0]--;
5875
5876 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5877 if (found_key.objectid < min_objectid)
5878 break;
5879 if (found_key.type == type)
5880 return 0;
5881 if (found_key.objectid == min_objectid &&
5882 found_key.type < type)
5883 break;
5884 }
5885 return 1;
5886}
5887
5888/*
5889 * search in extent tree to find a previous Metadata/Data extent item with
5890 * min objecitd.
5891 *
5892 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5893 */
5894int btrfs_previous_extent_item(struct btrfs_root *root,
5895 struct btrfs_path *path, u64 min_objectid)
5896{
5897 struct btrfs_key found_key;
5898 struct extent_buffer *leaf;
5899 u32 nritems;
5900 int ret;
5901
5902 while (1) {
5903 if (path->slots[0] == 0) {
5904 btrfs_set_path_blocking(path);
5905 ret = btrfs_prev_leaf(root, path);
5906 if (ret != 0)
5907 return ret;
5908 } else {
5909 path->slots[0]--;
5910 }
5911 leaf = path->nodes[0];
5912 nritems = btrfs_header_nritems(leaf);
5913 if (nritems == 0)
5914 return 1;
5915 if (path->slots[0] == nritems)
5916 path->slots[0]--;
5917
5918 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5919 if (found_key.objectid < min_objectid)
5920 break;
5921 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5922 found_key.type == BTRFS_METADATA_ITEM_KEY)
5923 return 0;
5924 if (found_key.objectid == min_objectid &&
5925 found_key.type < BTRFS_EXTENT_ITEM_KEY)
5926 break;
5927 }
5928 return 1;
5929}