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